4-Way Acoustically Transparent Masking

[ScottJ0007]

I've just completed my front screen wall with 4-way DIY masking.

Over the next few days, I'll post pictures of the screen, followed by diagrams and pictures of the building process. Bear with me as I do this because I'm a bit slow at getting the diagrams drawn and pictures taken and then uploaded to the internet.

Here is my front wall without the wall panels...
http://home.comcast.net/~scottj0007/theater/ScreenWall_B_1.jpg


Finished with masking at 16:9...
http://home.comcast.net/~scottj0007/theater/ScreenWall_B_2.jpg


Finished with masking at 2.35:1 ...
http://home.comcast.net/~scottj0007/theater/ScreenWall_B_3.jpg

[ScottJ0007]

I'm using a Panasonic AE1000 projector with a Prismasonic H-FE1500R anamorphic lens.

Here are some more pictures showing the masking.

Image size of 4:3
http://home.comcast.net/~scottj0007/theater/Masking_133.jpg


Image size of 16:9
http://home.comcast.net/~scottj0007/theater/Masking_178.jpg


Image size of 2.35:1
http://home.comcast.net/~scottj0007/theater/Masking_235.jpg


Image size of 2.40:1
(Notice that the top and bottom masking is moved in by a little bit compared to the picture above.)
http://home.comcast.net/~scottj0007/theater/Masking_240.jpg


(There is a bit of distortion in the above pictures because I am using a wide-angled lens on my camera. It is not there in real life. Also, I enhanced the photos by taking two identical images with the camera on a tripod. One is taken with the lights on and one with the lights off. I then superimposed the screen from the lights-out photo onto the lights-on photo. No other modifications were made to the images).

[ScottJ0007]

My masking system is probably more complicated than some of the others that have been described in this forum. I had a couple of special needs, that some of you may not have which means you can (and probably should) build a more simple solution.

My needs:
1) The masking material needed to be acoustically transparent. All of my speakers are behind an acoustically transparent SMX screen (127" wide). My speakers are moved to the very outside edges of the screen (In the very first photo in my first post, the speakers were closer together than where they are at now). When the masking moves from Cinemascope to 16:9, it covers the speakers.

2) On either side of my screen, I have doors that give access to the area behind my false wall. I wanted this access to remain clear of obstructions, therefore I could not use masking panels that slide back and forth on rails. Instead, I had to find a solution for my side masking that would fit in a space only a few inches wide.

3) Even though we talk about "constant height" I have found that I still need to make slight adjustments to the height of my screen for several reasons:
a) I have varying degrees of pin-cushion distortion with my lens set-up and I need to over-scan the image onto the masking more when I am in stretch mode than when I am in pass-through mode.
b) Any aspect ratio greater than 2.35:1 ends up being a little bit shorter in height compared to 2.35:1 unless you use the zoom feature on your projector. The exception would be if you have a scaler that will stretch in increments other than 1/3 (of course then you technically would need an anamorphic lens that would stretch in the same increment).
c) When I was building my screen and theater, I did not yet have the projector and lens. I wasn't exactly sure what height would eventually work in my room. I also wanted to future-proof my screen in case I ever get another projector or lens that has different throw characteristics.

Because of the above, I opted for four-way masking using rollers on the sides and using black GOM as the masking material.

Details will follow...

[ScottJ0007]

Here is a diagram of the side masking rollers and cables. This diagram is the top view, looking down on the assembly.
I will post some photos next.

http://home.comcast.net/~scottj0007/theater/MaskingSide_TopView_1.jpg

[doctorevil]

Very very nice Scott. Can't wait to see pictures of the system up close. It's a fantastic looking solution, which I'm sure many will want to try.

[ScottJ0007]

Here are some detail pictures of side masking rollers and cables.
Everything was purchased at Home Depot except the fabric, the aluminum pipe, and the pipe bearings.




http://home.comcast.net/~scottj0007/theater/MaskingSide_Photo_01.jpg


Patio door rollers mounted to strong-tie fittings found at Home Depot:
http://home.comcast.net/~scottj0007/theater/MaskingSide_Photo_02.jpg

Spring and turn-buckle bolt
http://home.comcast.net/~scottj0007/theater/MaskingSide_Photo_03.jpg

http://home.comcast.net/~scottj0007/theater/MaskingSide_Photo_04a.jpg
Note the back Gorilla masking tape. I had to use this because as the fabric rolls onto the pipe, the diameter gets bigger and the fabric begins to roll up faster. The cable has to roll onto the pipe at the same rate as the fabric or else it starts to bind. This is not an elegant solution, but it works. I wrapped several layers of tape where the cable starts on the pipe and then there are fewer and fewer as the cable wraps down the pipe, it was a trial and error effort that took some time to get right, but it works very smoothly now.

[ScottJ0007]

Here are some detail pictures of the bearing system I used for the vertical rollers. I can't stress how important it is to have the rollers operate smoothly. I had to completely scrap my first attempt because I tried to use electrical conduit pipe and PVC fittings for the vertical rollers. It was a miserable failure. This one works like a charm. I had to go to specialty suppliers to buy the aluminum pipe and the bearings.

http://home.comcast.net/~scottj0007/theater/MaskingBearing_Photo_01.jpg

http://home.comcast.net/~scottj0007/theater/MaskingBearing_Photo_02.jpg

http://home.comcast.net/~scottj0007/theater/MaskingBearing_Photo_03.jpg

[ScottJ0007]

That's it for the side masking. I'll post diagrams and pictures of the top and bottom horizontal masking later this week.

In case you are wondering... my masking system is not yet motorized. In all honesty it really doesn't need to be because it operates so easily and smoothly by hand. However, the COOL factor of a motorized system will probably entice me to add motors to it someday:cool:. It should be very easy to add motors to the roller bars.

As a side note... The masking probably cost me around $500 with all of the trial and error, including wasted materials and restarts. However, if you count the time I have spent, it has been ridiculously expensive. If I were starting over, I would probably look seriously at the HTIQ (http://www.htiq.com) masking system. I met Don at CEDIA and saw his product and have also exchanged a few emails with him. His motorization system is exceptional, but I don't believe he has a four-way masking system with acoustically transparent fabric at this time.

Let me know if you have any questions about my masking system so far. I will do my best to answer.

[kainers]

That looks amazing! Wow...

[mmmkam]

Very cool work. I was thinking of doing something very similar to this using IR motorized roller blind parts turned sideways. I am definetly going to keep track of this thread for ideas if I ever get around to building a masking system. Again great work!

[CAVX]

Yes, very good work and well thought out design :)

I am looking forward to the top/bottom masking as I want to rig a roll down side masking system and like the idea of the rollers...

Mark

[Nasty N8]

Very nice looking screen wall and a great idea. One question how do you have the material and the cables attached to the aluminum rod? Cable could prob be poked through a hole and clamped on the inside...but?

Nate

[oman321]

Your system is a thing of beauty and an inspiration. I wanted to do some sort of panel masking system because I like the clean look of the screen wall, but lately had been thinking it would be easier to do a motorized curtain set up. Now you have my wheels spinning.

Simply amazing, I vote for this to be the first sticky of this Sub Forum.

[ScottJ0007]

Very nice looking screen wall and a great idea. One question how do you have the material and the cables attached to the aluminum rod? Cable could prob be poked through a hole and clamped on the inside...but?
The GOM fabric is attached to the aluminum pipe with Gorilla tape (from Home Depot). The only trick is making sure you get the fabric on straight. The gorilla tape is amaizingly strong. I also allowed for one extra wrap of fabric around the pipe, which means the fabric is always applying pressure to the top of the tape, even when the masking is fully extended.

To attach the cable, I used a short metal screw with a washer on it. I pre-drilled a hole for the screw and then screwed it into the pipe. The end of the cable goes under the washer. It holds great, plus allows for adjustment if needed.

[stef2]

That's a very amazing setup...I will probably borrow one or two of your ideas when I build my masking system...I would like to see more pictures showing the relative distance between your screen, the screen frame, the moving boards covered with velvet and the removable panels that cover the whole setup. Again, congratulations, this is awesome! (any additionnal picture of your setup would be welcome...)

[ScottJ0007]

That's a very amazing setup...I will probably borrow one or two of your ideas when I build my masking system...I would like to see more pictures showing the relative distance between your screen, the screen frame, the moving boards covered with velvet and the removable panels that cover the whole setup. Again, congratulations, this is awesome! (any additionnal picture of your setup would be welcome...)
I'll post some more pictures later this week. (I would go take a couple pictures now for you, but the theater is in use by my daughter and four of her friends :) ). In the mean time, there is about 1/4" to 1/2" between my screen and the horizontal masking. The horizontal masking itself about 1/2" thick. Then there is only about another 1/4" of space between the horizontal masking and the vertical masking shown above. I was careful to keep everything pretty tight to the screen because I didn't want to get any shadows.

[ScottJ0007]

Stef,
Here is a quick and dirty diagram showing the approximate distances from my memory. I'll confirm and take some photos as well...
http://home.comcast.net/~scottj0007/theater/MaskingSide_SideView_1.jpg

[ht guy]

Scott is a genius...

[ScottJ0007]

Stef,
Here is a photo. It is kind of hard to take good pictures with the black background, but hopefully this gives you a good idea of the distances.
http://home.comcast.net/~scottj0007/theater/masking__spacing.jpg

[ScottJ0007]

Now for the horizontal masking...

When I designed my horizontal masking, I didn't have any significant limitation for space above or below the screen so I decided to attach the masking to the back of the false wall. The concepts however can be modified if you want to use some of the ideas for a situation where you want the horizontal masking to be place in front of the screen.

I am finding that it is a little hard for me to describe my setup in words and two-dimensional diagrams, and the photos that I have tried to take are not as clear as I had hoped. (Photos of black on black are not easy).

The way I am going to try to do this is in steps. First, I need to explain how my screen is attached. I made my own screen frame out of 3/4" maple and intentionally did not put a boarder on the screen. Boarders add thickness to the screen but I wanted my masking to hug the screen as close as possible. Plus, my masking provides the boarder as seen in the pictures above.

The screen is attached to the back side of the false wall. I have two 1 X 4 pieces of board that span the distance of the screen opening. On the top board, I have an aluminum "U" channel attached to the bottom edge of the board. On the bottom board, I have an aluminum "J" channel attached to the top edge of the board. I made the "J" channel by taking a piece of "U" channel from Home Depot and simply cutting off part of the front "U" with a carbide saw blade on my table saw (be sure to wear EYE PROTECTION!). I install the screen by slipping it up into the "U" as far as it will go and the swinging the bottom of the screen into the "J", clearing the front edge of the "J". When the screen bottom hits the back of the "J", I drop it down. This setup makes it easy for me to remove the screen any time I need.

You can see the 1X4 boards and aluminum channel in the very first photo that I posted in this thread.

Here is a diagram...
http://home.comcast.net/~scottj0007/theater/Masking_Horizontal_01.jpg


I will post some photos later.

[stef2]

Stef,
Here is a photo. It is kind of hard to take good pictures with the black background, but hopefully this gives you a good idea of the distances.
http://home.comcast.net/~scottj0007/theater/masking_spacing.jpg


Thanks...Exactly the angle I wanted to see! :)

[ScottJ0007]

Horizontal Masking...

I know this diagram and the last one are pretty busy. Sorry about that but it is easier for me to explain it this way than trying to put it into words. After this I'll post some pictures...

http://home.comcast.net/~scottj0007/theater/Masking_Horizontal_02.jpg

[sknyfs]

Quick simple question (I hope). How does the side masking stay in the respective positions (1.78, 1.85, 1.33, etc.) I don't see a hook or some to keep the maskingin place. With teh rollers and the springs wouldn't it just roll back up?

[ScottJ0007]

The side masking simply stays where I put it. That is the beauty of the cable system. The cables put just enough tension on the vertical board to hold it perpendicular, but they do not pull it in either direction. Using about a pound of finger pressure, I just pull or push on the vertical board to slide it where I want it to go. (It will be very easy to motorize someday).

[ScottJ0007]

Here is my framing for my screen. It is 3/4" thick with no boarder.

http://home.comcast.net/~scottj0007/theater/masking__0000.jpg

[ScottJ0007]

These photos are of the upper left corner of the masking, from the front side:

with screen in place, side masking removed -
http://home.comcast.net/~scottj0007/theater/masking__0001.jpg

without screen in place, side masking removed -
http://home.comcast.net/~scottj0007/theater/masking__0002.jpg

-masking fully extended
http://home.comcast.net/~scottj0007/theater/masking__0003.jpg

[ScottJ0007]

These photos are of the upper left corner of the masking, from the BACK side:

with screen in place, side masking removed -
http://home.comcast.net/~scottj0007/theater/masking__0004.jpg


http://home.comcast.net/~scottj0007/theater/masking__0005.jpg

http://home.comcast.net/~scottj0007/theater/pipe_roller.jpg

[ScottJ0007]

These photos are of the lower left corner of the masking, from the front side:

with screen in place, side masking removed -
http://home.comcast.net/~scottj0007/theater/masking__0006.jpg

the "U" channel for the cross bar is essential. Without it, the cross-bar tends to flop forward. It also guides it within 1/4" of the face of the screen.
http://home.comcast.net/~scottj0007/theater/masking__0007.jpg

-notice in this picture that there is a zip-tie wrapped tightly around the end of the cross piece of aluminum, inside of the aluminum "U" channel. This has two purposes, first it makes it more snug, and secondly, it helps the two pieces of metal slide easily and quietly.
http://home.comcast.net/~scottj0007/theater/masking__0008.jpg

with masking fully extended -
http://home.comcast.net/~scottj0007/theater/masking__0009.jpg

[ScottJ0007]

This photo is of the lower left corner of the masking, from the BACK side:

http://home.comcast.net/~scottj0007/theater/masking__0010.jpg

[ScottJ0007]

These photos are of the lower right corner of the masking, from the front side:

- masking fully extended
- also notice that there is no hem in the GOM fabric. A hem would stop the freying of the material, but it would also double the thickness on the edges and would cause problems when it rolls onto the roller bars. Instead, I used a product called "frey check". It is basically a fabric glue that I applied to all exposed edges of the GOM. It should never frey more than what you see in these pictures.
http://home.comcast.net/~scottj0007/theater/masking__0011.jpg

http://home.comcast.net/~scottj0007/theater/masking__0012.jpg

[ScottJ0007]

Final photos:

http://home.comcast.net/~scottj0007/theater/masking__0013.jpg

http://home.comcast.net/~scottj0007/theater/masking__0014.jpg

And finally, just to show what it looks like with the masking fully extended to its limits. http://home.comcast.net/~scottj0007/theater/masking__0015.jpg

[ScottJ0007]

Sorry for the ad-nausea detail, but it is the only way I thought I could adequately describe my setup.

As I said earlier, I hope to motorize it someday. It should be very easy to attach motors to the roller bars. The trick will be getting a controller system that allows for multiple pre-set stopping points with an IR remote.

[hlomax]

Fantastic job.. Looks like something anyone of us can build.. or modify to fit in our theaters ..

Great job!

[Wazzey]

Thank you very much for the detailed pics... The horizontal project is what I was needing. I'm sure I'll be back with questions when I get into it but you did such a good job explaining it hopefully I won't have any. Thanks again for taking the time.

Mike

[ScottJ0007]

You're welcome. I think masking is a great enhancement. I hope the explanations help other AVSers consider building a system. Let me know if you have any questions.

[BamBamF16]

Scott,

I have a question about the horizontal masking. Does the board sewn in the pocket ever sit in front of your mains? Or does the bar move outside the mains in 2.35 mode and inside when smaller? Is my question making sense?

Thanks,

Jeff

[ScottJ0007]

I have a question about the horizontal masking. Does the board sewn in the pocket ever sit in front of your mains? Or does the bar move outside the mains in 2.35 mode and inside when smaller? Is my question making sense?
Your question makes sense. If you are referring to the vertical board that is sewn into the side masking, the answer is no, it never sits in front of the speakers. I placed the speakers so they are just inside the screen when it is in 2.35 mode. When I switch to 16:9 mode, the masking material (GOM) covers the speakers, but the board is passed the speakers.

[BamBamF16]

Scott,

Thanks for the reply, that is exactly what I meant. Your system is awesome. If I had the room for a false wall, I would definitely give this some serious consideration and effort. Great job!

Jeff

[ilsiu]

I also wanted to say what a fantastic job you did. Probably the best engineering solution (concept and execution) I've seen (DIY or otherwise). I also think the overall look of the entire theater is very elegant and attractive. Thanks for providing detailed descriptions and photos of your design - very generous of you.

[Nasty N8]

Yes thank you very much looks great. The weight of the steel and aluminum bars counter weigh each other to keep it in position? This makes me want to tear my wall apart to start building.

Nate

[ScottJ0007]

Yes thank you very much looks great. The weight of the steel and aluminum bars counter weigh each other to keep it in position? Yes, exactly. Without the lower masking to act as a counter-balance, the top masking would just roll down due to the weight of the bar.

While we are talking about the bars, let me add that the bars for the lower masking gave me a lot of headaches before I got it working right. I first tried a 1/4" X 2" steel bar and did not use the side "U" channel. This didn't work at all. Steel is much heavier than aluminum and the steel would just bend in the middle out away from the screen and then fall forward.

Rather than the 1/4" aluminum, another option would have been to use a thicker material like 3/4" wood. This would have been a little more simple and cheaper, but I was a bit paranoid about keeping the masking very close to the screen. Using thicker material would have moved the side masking further away from the screen. My solution might be overkill.

If I were starting over on the masking I would probably put some more thought into trying to do the top and bottom masking more like I did my side masking. I think with a little bit of thought, one could come up with a solution where all four sides of the masking were built in the same way with the same roller bars, bearings, and cabling setup. I'm pretty sure it would be possible to come up with a system that could be surface mounted and would work for someone who does not have a false wall.

[Gerry S]

Like everyone else, I want to commend you on an excellent job, and thank you for sharing all the details.

Could you please provide an explanation of the steps you take when switching between the different aspect ratios? Do you move your lens out of the way for 16:9 and 4:3? Do you have to tell the projector to "unstretch" the image? Is any refocusing required? Thanks again.

[ScottJ0007]

Could you please provide an explanation of the steps you take when switching between the different aspect ratios? Do you move your lens out of the way for 16:9 and 4:3? Do you have to tell the projector to "unstretch" the image? Is any refocusing required?

I use a Prismasonic H-FE1500R anamorphic lens (http://www.prismasonic.com/english/description_hfe1500r.shtml). This lens has a "pass through" mode. I just hit a button on my remote to change from stretch mode to pass-through mode. I also hit a button on my remote to change my Panasonic AE1000 projector from "virtical stretch" to 16:9 mode. That's it. No adjustments to focus or zoom.

[Alain Singapore]

I also find that your masking system is really outstanding. I tried putting something like that toguether too but I gave up half way as it was too time consuming.

I have a couple of question:

You could have run your cable to link the left to the right so that a pull from one side would have moved the other side in a symetrical way. Is there any reason why you did not synchronized the side masking?

How do you proceed to adjust the masking? Do you have marks to indicate where to stop for the various aspect ratios?

[ScottJ0007]

You could have run your cable to link the left to the right so that a pull from one side would have moved the other side in a symmetrical way. Is there any reason why you did not synchronized the side masking? In my original plan, I did intend to put a cable between the two roller bars so that the masking was synchronized. I still may do this but just haven't yet. It will only take a couple minutes to do.

For anyone wondering how this would work, I will simply use the same vinyl aircraft cable that I used for the rest of the masking and loop it around each of the vertical rollers for the side masking. However, I will cross the cable between the rollers so that it is in a figure 8. This will cause the rollers to turn in opposite directions. (If this doesn't make sense, just try it by putting a rubber band around two pencils and then spin the pencils between your fingers to see how crossing the rubber band in a figure 8 changes the direction of the spin.) I will also put a turn-buckle bolt on the cable so I can easily adjust the tension.

How do you proceed to adjust the masking? Do you have marks to indicate where to stop for the various aspect ratios? I have a very LOW-tech method that I use :eek:. I display the picture first, and then just move the masking to the edge of the picture. If I ever motorize the system, I would like to find a motor control that has multiple pre-set stop positions. This would enable me to just push a button and have the masking move to the pre-determined stopping points.

[VTPete]

Scott,
Absolutely amazing! Thank you so much for taking the time to document and post all of this wonderful detail. Reading through this thread has been a ton of fun and informative as well. Your posts, IMHO, are representative of the very best posts of the very best forum in the world. Kudos.
-Pete

[ScottJ0007]

Thank you Pete. I appreciate receiving the compliments from everyone. I have learned so much on this forum from other people. It is nice to be able to give back in a small way.

[Axel]

Scott;
Very impressive work. Congrats! Thanks also for your detailed descriptions. It is an excellent source for ideas and inspirations.
____
Axel

[Andy238]

Great job, Scott. I'm going to shamelessly steal your design :)

Your "low tech" positioning method sparked a thought about motorization...
Everyone, commercial folks too, always talk about/use preset positioning to control the motors. Is there a such a thing as a light sensitive sensor that can sense the brightness of being "in the beam" of the projector? That way the system could be self positioning and not depend on preset locations.

To get a feel of what I mean, hold your hand against your screen at the black border and stick your finger just inside the edge of a projected image. See? Your finger is brighter than when it was out of the image. A sensor could detect that difference and stop the masking at that spot.

Just a thought anyways. Again, nice job, Scott!

[ScottJ0007]

Thanks Andy. I've read a couple of threads on other forums where people have toyed with photo sensors to sense the light and automatically position the masking to the light. The problem comes when there are dark scenes. You don't want your masking to try to reposition itself every time the screen goes dark during a movie. To get around this, people have added timers to the photo sensors so that the masking only moves when the photo sensor is dark for longer than say, 20 seconds.

This all gets WAY over my head in terms of electronics and motor control. I think I'll be happy if I can just figure out simple presets with flash memory and basic IR control.:D

You are welcome to "steal" any ideas you want. If you get started on the project, feel free to PM me if you would like and I'll be happy to discuss more detail or suggested alternatives.

[Andy238]

Thanks for the info offer. I'm in the stage/screenwall contruction phase now and I'm sure I'll have more questions as I get closer to the masking system.

Cheers,
Andy

[Dark_Wizard]

Scott...awesome job! This is definitely an inspiration and like Andy238 I am at the same stage of my HT and will make for provisions to add this at a later time as time and money is a big concern right now.

[GetGray]

Scott: Nice job. Clever mechanical designs with off the shelf parts. I especially liked the way you got your horizontal masking coupled. Good idea. I also might borrow your ideas and make a motor controller for it. If I ever get time and do it, I'll fix you up with one. Thanks for taking the time to share the excellent work.

I wondered why you didn't use matching velvet on the maksing panels, too? Not (acoustically) transparent enough? Too (light) transparent? Velvet "crush" when rolled?

Cheers, Scott

[ScottJ0007]

GetGray,

Thanks.... I didn't use the black velvet on the panels because I didn't think it would be acoustically transparent enough. The black Fidelio velvet is a lot thicker and denser and also has a backing material. It is also quite a bit more expensive than the GOM. I didn't do any acoustical testing though so the velvet may have been fine to use. I just based my decision on "gut feeling".

I wish I knew more about motors and motor controllers. If you ever make one, I'd be very interested in buying one from you! I've done a lot of looking at kits and online companies, but I don't know enough about electronics to fully understand what I need.

[HDGTX]

Here is a diagram of the side masking rollers and cables. This diagram is the top view, looking down on the assembly.
I will post some photos next.

http://home.comcast.net/~scottj0007/theater/MaskingSide_TopView_1.jpg

Hi Scott,
Wonderful creation you have crafted !
Are the two vert masks mechanisms connected in some way, so they will move together ? I see in your drawings the horiz masks move together, one up & the other down. Do you just pull on the edges to move the masks ? The screen shots showing the different ARs
was very helpful.
Thanks for the great drawings, photos & text.
Great job !

John

[ScottJ0007]

John,
Right now the two sides are not connected. In my original design, I had planned on connecting them with another cable between the roller bars. However, it is so easy to move the panels by gently pulling or pushing on the edges, I never added the connection. When I add motorization, I will probably connect the two sides so they move together.
- Scott

[HDGTX]

Sorry for the ad-nausea detail, but it is the only way I thought I could adequately describe my setup.

As I said earlier, I hope to motorize it someday. It should be very easy to attach motors to the roller bars. The trick will be getting a controller system that allows for multiple pre-set stopping points with an IR remote.


Scott, its me agin. I just ran across an option for motorizing masks on another thread here, from poster Gary Murrell at the link below:

http://www.avsforum.com/avs-vb/showthread.php?t=817776

He used a drapery motor from SmartHome that can be RF controlled. Nit sure, your drapes my be too heavy for this motor work with, but take alook & see what you think:

Motor: $100

http://www.smarthome.com/3142.html

RF Rmt: $25

http://www.smarthome.com/includes/showimage2005.asp?img=/images/3150side2big.jpg

[Andy238]

Hey Guys,

I've also been thinking about using Scott's design and motorizing it. Here are some of my thoughts:

Motor:
I also saw the Add-a-Motor gadget and am planning on using that or something similar. The only thing I don't like about that particular motor is that you only have "open" and "close" stops. You can't have a third stop for say, 1.85. You've only got open (for 2.35) or close (for 1.78). Although, I suppose a second motor could be added with the stops set for 1.85 viewing.

Side masking:
I was also wondering about what happens when you reverse the motor and how the panels have to move. So I came up a counterweight system to move the panels when revering the motor. I had seen this idea before so I can't take credit it though. ;)

Design change:
I did think about one design change though. Instead of an Al tube and bearings, I was thinking of using off the shelf roller shades from here http://www.blindsgalore.com/ProductList.asp.

I'd pick the cheapest shade since the actual shade doesn't matter as I'd replace it with black GOM anyway. They come with the needed brackets and a continuous loop cord that will fit right in with the motor. Easy automation! Since my screen is 50 inches high I'm planning on a 57 inch wide shade.

So here are some sketches of my implementation of Scott's design. Keep in mind I'm only concerned with side masking. The horizontal masking will be fixed and not adjustable.

What do ya think?

Andy

[benwillcox]

Hi Scott,

Found your thread a few days ago, and I'd like to say thanks for taking the time to document this, as well as providing the very detailed diagrams!

I had been (slowly) working on an automated side masking system whilst constructing my cinema, unfortunately at the final stages where the masking material was fitted to the system, it didn't quite work as well as I'd hoped due to the material bunching up at the bottom. So, now having seen your design, I am going to attempt to build a version of it (but I only need side masking as I'm using CIH)!

For those talking of motorizing the masking system, the system that I designed uses automation to move the masking to ANY aspect ratio desired - fortunately, this part of my project was the part that actually worked properly! :D

In a nutshell, you pass the desired aspect ratio to the system as an integer between 1 and 2350 (or whatever your max aspect ratio is), and using an optical encoder it will move the masking to the correct point.

I have documented it here: http://www.willcoxonline.com/masking/ which I think would also work using your mechanism, but with a few mechanical modifications of course.
I would imagine that it would be possible to modify the add-a-motor drive unit to add an optical encoder in the same way, however I'm planning to look at alternative motors as I'd like to get the system as silent as possible and the one I've used is a little noisier than I want, and I understand the add-a-motor is a bit noisy also.

Thanks,
Ben

[HDGTX]

John,
Right now the two sides are not connected. In my original design, I had planned on connecting them with another cable between the roller bars. However, it is so easy to move the panels by gently pulling or pushing on the edges, I never added the connection. When I add motorization, I will probably connect the two sides so they move together.
- Scott

Thanks for the info Scott, good to hear how easily the masking panels move back & forth, prof of a design done right ! Please keep us posted when you do motorized your system. Your theater is amazing, you are blessed my friend !

[ScottJ0007]

I just ran across an option for motorizing masks on another thread here, from poster Gary Murrell at the link below:
...
He used a drapery motor from SmartHome that can be RF controlled. Nit sure, your drapes my be too heavy for this motor work with, but take alook & see what you think:
...
Thanks. I have considered that motor but I have some of the same concerns as Andy. Also, it does not appear to be able to move in either direction from a given stopping point. When you reapply power, it continues on in the same direction until it reaches the end and then stops. When you reapply power, it then reverses in the opposite direction.

Also, I would like to find something with IR control rather than only RA control. I would like to be able to program the movement of the masking into a standard universal remote.

[ScottJ0007]

So here are some sketches of my implementation of Scott's design. Keep in mind I'm only concerned with side masking. The horizontal masking will be fixed and not adjustable.

What do ya think?
Andy,

Very impressive drawings! Here are a couple of things to consider.

First, the counter weight idea is a very good idea and will actually resolve a number of issues I had with keeping the right amount of tension on the masking material. However, it will require the use of a motor with enough torque to act as a break so that the counter weight doesn't pull the masking closed even after the motor stops.

Second, I found that is was very important to have the rollers spin extremely easily in order for the whole system to work smoothly. My masking glides back and forth with very light finger pressure. All of the off-the-shelf roller shades that I found were not smooth enough and had too much play. This might be a non-issue with the counter-weight design that you have. If so, your design would be much easier to implement.

[ScottJ0007]

Hi Scott,
For those talking of motorizing the masking system, the system that I designed uses automation to move the masking to ANY aspect ratio desired - fortunately, this part of my project was the part that actually worked properly! :D

In a nutshell, you pass the desired aspect ratio to the system as an integer between 1 and 2350 (or whatever your max aspect ratio is), and using an optical encoder it will move the masking to the correct point.

I have documented it here: http://www.willcoxonline.com/masking/ which I think would also work using your mechanism, but with a few mechanical modifications of course.
Ben,
Wow! I studied your web site and am very impressed with you electronic design abilities. I'm afraid though that most of it is beyond my level of knowledge. I'm having a hard time even understanding what all the symbols mean on your schematic, let alone understanding how to build it :confused:. I've done a little bit of reading on motor controllers but I always get stumped on the encoders and the programming.

Do you have to re-program the controller if you lose power? Can you move your masking as part of a macro in a universal remote or do you alway have to be hooked up to a PC?

This is my wish-list of what I would like a motorization system to do:

1) It should be able to move both the horizontal and the vertical masking by remote IR and/or RF control. The IR should be “learnable” so that it can be controlled by a universal remote like the Harmony or Pronto series.

2) It should move both the horizontal masking and the vertical masking to a minimum of 5 pre-determined set points for various aspect ratios (4:3, 16:9, 1.85:1, 2.35:1, 2.40:1). It should be extremely accurate and repeatable in its positioning. In addition I would like to be able to move the masking manually with the remote to any other aspect ratio as needed.

3) The masking should move from its current position directly to the preset memory position with the touch of one button on the remote. In other words, it should not have to “reset” itself by returning to the full open or full closed position prior to going to the desired preset position. Also, it would be nice if the controller had a speed control process so that it would quickly move to the desired position and then slow down for the last couple of inches.

4) It should have stop limits for the fully closed and open limits of the masking system.

5) I would also like a wall switch that functions similarly to the remote so that I can move the masking even if I can’t find the remote.

6) The preset stopping positions should be easy to set. For example, I would like to be able to manually move the masking to the desired position and then press a “set” key on the remote followed by the desired Preset Key on the remote to set that desired position.

7) The system should not lose its memory in the event of a power failure.

It seems that all of this should be very do-able for someone who has enough electronic design knowledge and knows where to buy all the parts.

One of my biggest requirement is that they system has to be easy to use. That is probably why I am not overly dissatisfied with my manual setup. Even my wife can set the masking now!

Thanks for posting about your system. It certainly lets me know it is all possible. I'm very impressed!

- Scott

[benwillcox]

Ben,

Do you have to re-program the controller if you lose power? Can you move your masking as part of a macro in a universal remote or do you alway have to be hooked up to a PC?


Hi Scott, no, nothing has to be reset if the power is lost. I don't have a direct interface to an IR remote control, that would have to be built as an additional interface to make it stand-alone, although in theory I could do that via the HTPC.

However, the way it's designed to work is that you don't actually need a remote control to set the ratio - the video player running on the HTPC (VLC player) automatically detects the aspect ratio of the movie, and sends that data to the masking system. This means that everything is fully automatic, you just play the movie, and whatever the aspect ratio, the masking moves to the correct place!
It doesn't get much more easy to use than that! :D

Cheers,
Ben

[ScottJ0007]

This means that everything is fully automatic, you just play the movie, and whatever the aspect ratio, the masking moves to the correct place!
It doesn't get much more easy to use than that!
Very cool!

[Andy238]

Ben, that is a nice system. I agree with Scott though... most if the info on the website was over my head too. And I even know what the symbols mean! :D But what if you aren't using an HTPC? I have one but I"m still not sure if I am going to go that route for my final setup.

For me, I"m not looking to go THAT diy on the motor control system. I'd rather just attach a IR contollable motor, set the stops, and be done. Don from HTIQ is working on providing just his motor control system which is pretty robust as far as what we're looking for and what Scott outlined.

So Scott, you think the aluminum pipe is the way to go. There is a Metal Supermarket about an hour or so away from me. I'll have to call them and see what is available. Good catch on the torque and motor break issue. I hadn't thought of that. Hopefully Don's motor will work. If not do you suppose a second motor could do it? Maybe attached to the opposite roller?

I once read about someone using a linear actuator. I wonder if that could be useful somehow...

Andy

[Nasty N8]

I was looking at the linear actuators also but you still need a controller system and I do not think you can get accurate stops out of them accept for full open and full closed. Looks like Dons setup is the way to go.

Nate

[HDGTX]

Ran across this company, Leg Motorized Systems, which builds motorized drapery systems. Did not see any pricing
given, would imagine they are expensive. They also build an add-on cord pulling motor, looks like it only has two stops as well. Would any of their products be of help to guy guys for powered masking ?

http://legmotorizedsystems.com/

[HDGTX]

Here is another possible choice for roller shade motors. Saw these Somfy roller shade motors on AV Outlet's web site. The page in the link below shows their in tube roller motors that are battery or tranformer powered. You can buy just the motor or any & all other pieces: brackets, roller tubes (Rollease brand).
From what I read, they have a memory that can hold three setings; FulluUp, Full down & one other specified postion (not sure if these are user setable or dealer does it). Maybe this would help provide (full open for 2.35, full closed for 4:3 & the other position for 16:9). Many are IR controlable & some you can add RF.
I can see them working in the horz position, but how well will any roller shade mech (manual or motorized) work, standing on it's end for vertical masking ?

Take a look & see what you think ?

http://www.av-outlet.com/en-us/dept_496.html


John

[Andy238]

Awesome finds, John! Somfy would be the way to go but their IR control is not learnable to other remotes unless you get a $200 module. That would be a deal breaker for me anyway. I just started looking on the av-outlet site. Lots of stuff, more to see...

I'll also fire off for a quote on the LEG motors and see what just the motor is going for. I'll post any replies I get.

Cheers,
Andy

[Nasty N8]

Wow that looks to be perfect get it in the end of Scott's tube and we have motorization. They have an RS232 option perfect for setting exactly what you want.

Nate

[benwillcox]

I can see them working in the horz position, but how well will any roller shade mech (manual or motorized) work, standing on it's end for vertical masking ?


Thanks for posting the link, these motors look ideal for this application. It looks like it should be fairly straightforward to fit these using the same type of mechanism that Scott has used for his masking.
I also found this link http://www.skycoshade.com/skylight.html which shows this type of motor in use for blinds where the material needs to be kept in tension, such as side masking.

I still think that they would need a different type of control system to cope with more than the three fixed position it appears they support, although that may be enough for some.

Cheers,
Ben

[Andy238]

Well, av-outlet has an IR controller called "AVUA-IRRTS Universal Automation Interface" that looks like it will do 5 positions. That's cool. But the price is over $200. That's just the IR interface too. Not cool. Add a motor and you're well over $300. Don's (htiq) motor only package is a less than that (early estimate anyway) and is more precise.

Hey Don, is it soup yet! :D

So why are these things so pricey anyways? :confused:

[ScottJ0007]

Great finds guys. I've looked at the somfy motors but they seem a bit pricey and lack some of the flexibility that I think I would want for the masking application. I agree with Andy that Don's (HTIQ) (http://http://www.htiq.com/index.php) setup would be great if he decides to sell a motor only package and it is in the right price range.

[HDGTX]

Ben, thanks for the neat "skycoshade" site, wish they gave more detail on their products. Look forward to hearing what you find out from either company.

Here is Somfy home page, interesting animations, on their roller shade prodcuts:

http://www.somfy.com/au/index.cfm?page=/au/home/products/roller_shutters/control_options&language=en-au

[HDGTX]

Ran across this link (news from 11-14-07) about Somfy having a next gen "ILT" motor coming out. From what I read the motor has built in intelligence, each mtr has a unique address. The mtrs on the network communnicate via a protocol allowing intergration w/ 3rd party automation sys capable of dry contact, RF, IR, RS-232 or RS-422. See link below:

http://hiddenwires.co.uk/resourcesnews2007/news20071114-03.html

Guess for a motor to stop in the right place (putting the masks where we want it) means that mtr has to be smart
& know exactly where it is & where it is going & that takes a control system of some kind to make it happen. Starting to sound expensive... :eek:
Hey Don @ HTIQ, how's your system coming along ?

John

[w84no1]

Found this, might be of some use.
http://www.remotecontrolcurtain.com/

[Andy238]

Mmmm. Interesting....

[HDGTX]

What would make for a good motor to use on masking systems ? I ran across the web site below & they had many types. They have all sorts of hobby & robitics stuff on their site. www.alltronics.com

Found one 12VDC Pittman type motor w/solenoid (part# 24M015) with encoder attached for $20.
There was a 24VDC Coleman gearmotor for $20 (# FYQF63600 30-5).
An AC gearmotor w/brake (# 23M030), 147 RPM,
Then there was a motor with a solenoid activated brake that releases upon power up for $20
A US Digital optical encoder (Part# E2-1016-250-G) 1016 pulses per revolutionwith 1/4" shaft. Does anthing sound useful here ?
Figured a slow RPM was useful & maybe a controller would need an optical sensor to get feedback from the motor.

John

[benwillcox]

What would make for a good motor to use on masking systems ? I ran across the web site below & they had many types. They have all sorts of hobby & robitics stuff on their site. www.alltronics.com


Hi John,

The criteria I would look for in a motor are that it needs to be geared, low voltage DC to allow easy solid-state switching (i.e. no relays) and speed control if desired, an encoder to give feedback for precise positioning, and quiet operation. It may or may not need an electro-magnetic brake, depending on the intertia of the rotor and gearbox of the particular motor.

Cheers,
Ben

[camarillo_cinema]

Hey Don, is it soup yet! :D



Not soup just quite yet, but it's on the burner. I want to roll out the IR/RS232 combo, as well as the dual - motor controller. These controllers have been "rock-solid" for about 2 years now. The encoder makes it so you can have presets (up to 10).

These will be ready at the end of January.

Don

[HDGTX]

I noticed in the regular screen section a recent post by Danny Marvomatis regarding his new Marvomatic controller (used to control a Stewart masking system). See the link below:

http://www.avsforum.com/avs-vb/showthread.php?t=975908

What do you guys think ? Wonder if it can by used or adapted to work with 4-way masking (buy a second board for vertical masks)? It has three presets; 1.85, 2.35 & 2.40, plus manual toggle for top & bottom masks. No pricing shown.

HTIQ's controller has 10 presets, I believe. :)

[HDGTX]

Not soup just quite yet, but it's on the burner. I want to roll out the IR/RS232 combo, as well as the dual - motor controller. These controllers have been "rock-solid" for about 2 years now. The encoder makes it so you can have presets (up to 10).

These will be ready at the end of January.

Don


Hi Don, when you say dual motor controller, are you meaning that one controller will control a seperate motor for Horz masks & a seperate motor for the Vert masks ?

Would these need to be a specific type motor or even a certain model motor to work properly & accurately with your controller ?

Do you have a price for this dual controller at this point ?

Thanks ! :)

[camarillo_cinema]

John-
I have a dual-motor controller. The 4-way masking can be done with 2 motors. You will need 12VDC gearmotors rated at about 175 oz-inches.

Don

[HDGTX]

Don,
Thanks so much for the info.
Good luck with all your many projects that you have going on. You are a busy man!

John

[Freddie]

Thanks Scott for a great thread....you just gave me another project to do this winter..... I just replaced my 16X9 screen with a CIH by Carada and have been considering the side masking idea then I ran into this thread...

Okay to pm you and throw some idea's your way on just a side masking system?

tia

Keith

[Axel]

Thanks Scott for a great thread....you just gave me another project to do this winter..... I just replaced my 16X9 screen with a CIH by Carada and have been considering the side masking idea then I ran into this thread...

Okay to pm you and throw some idea's your way on just a side masking system?

tia

Keith


Keith;
If possible, I would appreciate if you could keep your idea exchange public, i.e. by adding to this thread or if needed by creating a new one. One the main reasons for having this forum is to provide a platform for others to learn as well....
Having said this (selfish me), I would be very interested in your thoughts on how to make a masking system with my Carada Criterion CIH setup... :) The problem I am facing right now is to get the masking panel close enough to the screen material (< 1/2") so it does not cast a shadow. Any pointers/ideas?
____
Axel

[Freddie]

Axel,

Will do that, and you are correct this is a public forum and hopefully share some idea's and maybe spark an idea from other members. Working on the same problem you are having trying to get the masking material close enough to not cast a shadow...

Keith

[camarillo_cinema]

Most of the commercial screen companies mount the screen material on the back side of the frame. Since the frame has a dimension, that means that any masking of the screen places the masks some distance away from the screen material itself.

From my experience, this doesn't pose a problem, so long as your masks are not too far from the screen. Since your projector blasts light straight on, the "shadows" will be behind the masks.

Don

[Axel]

Most of the commercial screen companies mount the screen material on the back side of the frame. Since the frame has a dimension, that means that any masking of the screen places the masks some distance away from the screen material itself.

From my experience, this doesn't pose a problem, so long as your masks are not too far from the screen. Since your projector blasts light straight on, the "shadows" will be behind the masks.

Don

Yep, that's it Don!
In my case with the Carada Criterion this distance is approx. 1.5" and the masks unfortunately cast a noticeable shadow from the first row (primary seating location - approx 12 ft away from screen). Any good ideas for me?
____
Axel

[camarillo_cinema]

Axel-
If you are masking a screen that has a recessed frame, then there's no getting around the 1.5 inches for the masks. In fact, this may end up being more than 1.5 inches, since the masks typically don't sit right on the frame.

I just did a theater here in LA, where we masked a 12 ft Carada. Depth of frame is probably same as yours. However, I haven't noticed any ill effects of having the masks that far away from the screen material. Again, it will depend on your seating distance as well. The only way around this is to turn your screen around. ;)

Don

[ScottJ0007]

I’ve been away a couple of days. Great discussions!

Not soup just quite yet, but it's on the burner. ...These will be ready at the end of January.
Don, this is very good news! Keep us posted.

John-
I have a dual-motor controller. ... You will need 12VDC gearmotors rated at about 175 oz-inches.
Don, With the package you are putting together, will you include your motors? Also, have you added non-volitile memory to your controller so it doesn't loose its settings if the power goes off?

I noticed in the regular screen section a recent post by Danny Marvomatis regarding his new Marvomatic controller (used to control a Stewart masking system). See the link below:
http://www.avsforum.com/avs-vb/showthread.php?t=975908
What do you guys think ? …
Very interesting prototype. It looks like the Marvomatic controller has some real potential if Danny continues his R&D. His video is pretty cool too. Currently however, I think Don’s controller has more features and is much further developed and tested. It looks like Don’s HTIQ controller will be available as a stand-alone product very shortly, but it looks like the Marvomatic might be quite some time away from production.

…Okay to pm you and throw some idea's your way on just a side masking system?
Keith
Keith, It is fine to PM me, but I agree with Axel that if it is a question of general interest, it would be best to keep it public.

Keith;
Having said this (selfish me), I would be very interested in your thoughts on how to make a masking system with my Carada Criterion CIH setup... :) The problem I am facing right now is to get the masking panel close enough to the screen material (< 1/2") so it does not cast a shadow. Any pointers/ideas?
Axel

Axel, Keeping my masking as close as possible to my screen was a big concern of mine as well. The only ideas I have are 1) As Don already mentioned, if possible you might consider mounting your screen to the back side of the frame so that you eliminate the “box effect” of the frame itself. 2) The only other idea I would have would be to build a lip on the edge of your vertical masking panel that protrudes towards the screen. The lip could be built from very thin and lightweight material since it would not have any load bearing requirements. You could cover it in the same material as the masking panel. The downside to this option is that you would not be able to retract the masking past the edge of the screen because the lip would catch on the side frame. I’m not sure if this would be a problem in your setup or not.

[Freddie]

Axel

I think Scott is talking about what I was going to try and do.... Basically give up a little screen real estate on either side to have a cutout that would travel very close to the screen while the rest of the material would stay the 1.5" away.... maybe using a piece of plastic or light weight fiber board?

Hopefully I get a drawing together and post it to see what everyone thinks...

Don and Scott thanks again for the assistance and valuable ideas!!

Scott maybe some time if you are in the Denver area you could stop by to see my modest theater.

Keith

[ScottJ0007]

Scott maybe some time if you are in the Denver area you could stop by to see my modest theater.
KeithKeith, I sent you a PM.
- Scott

[camarillo_cinema]

Don and Scott thanks again for the assistance and valuable ideas!!

Keith

No problem, Freddie...er, Keith! Keep on truckin'!

Don

[Andy238]

Hey Guys,

I've been thinking about this whole masking automation thing since this thread started. Scott's design is awesome and very doable for a DIYer. But the automation part is driving me nuts! :eek:

Everyone who posted here has had great ideas and great resource finds. It looks like everything we need to motorize Scott's design is out there. We've found motors, motor contollers, encoders, relays, IR controls, and hardware. But unfortunately not in one nice and tidy kit. Wouldn't that be nice ;) One thing I found out is I don't know enough about these gadgets to know how to connect them together!

From what I gather the best and most accurate control system uses a stepper motor, a stepper motor controller, and an optical encoder. I understand how a stepper motor works (is controlled by voltage pulses th rotate a specific amount per pulse). I understand what the encoder does (creates a pulse based on a rotating disk with light/dark bands). The part I don't know enough about is how these things work together, or rather how they are connected together, to make a complete control system. I'm just not an electronics whiz. Does anybody know how this stuff should be integrated that can help us out? I know Don does but he's working on his commercial version and I'm not sure if he is willing to share his secrets - which I totally understand, btw.

So here are some of the puzzle pieces. Also look at John's post above (# 79) for good finds.

So how do we put all this stuff together? :confused:

Andy

Contollers:
This is a very cool controller. For servos though not sure if useful for us. Includes an IR module and stores programming in EEPROM: http://www.pontech.com/products/sv200bc/index.htm

Controller kit: http://www.allelectronics.com/cgi-bin/item/SMKIT-2/305/STEPPER_MOTOR_CONTROLLER_KIT_.html
There a bunch more contollers out there too.

Encoder: http://www.alltronics.com/cgi-bin/item/24T001/search/USDIGITAL%2DE2%2D1016%2D250%2DG%2Doptical%2Dencoder

Motors: http://www.allelectronics.com/cgi-bin/category/400400/DC_Gear_Motors.html

IR Relay kit: http://www.alltronics.com/cgi-bin/item/KIT_142/29/12%2DChannel%2DIR%2DRelay%2DBoard%2DKit
For a non-encoder based control system... I think.

[GetGray]

Yes, the putting it all together is the hard part. Without having a kludge of parts anyway. An elegant solution that one can sell is tough though. In the US anything that has a microprocessor in it requires FCC part 15 compliance/certification. Unintentional radiators they are called (assuming no RF control), and they require electromagnetic emmissions and conducted radiation tests. The lab costs for that are very high, and that's if you pass. CE is worse adding ESD immunity testing at least. People think it's not big deal but it is really. The fines if you sell something that is not FCC certifiable can be as high as $10k per day :eek:. Even if you sell it as a "kit" (which is also against their rules). And they are quite serious about it.

Good news is if you only make 5 or less, for personal use, and don't sell them, you can be exempt.

That 's the beauty of a DIY and a forum though. If you can come up with a workable solution that people can put together from off-shelf parts, then they can get around the FCC regs and potential fines. You just can't bundle it up and sell it as a kit. Which bites :(. Of course chances of the FCC triangulating your device and knocking on your door may be low, but if you sell one of the buggers, and they get wind of it not being compliant, then you are way out on the proverbial limb.

I think there are outs for just selling a component (i.e. a circuit board that is a dedicated motor controller circuit only) so long as it is not a functional system. So alas, we are held to using piece parts to make it work. Still doable though.

[Andy238]

As Kramer would say, "oh, it's doable."

Just not by myself. :)

Working with piece parts works for me. Heck, I really don't care what the contraption looks like. It'll be "behind the scenes" anyway. I'm not looking to sell anything. It's for my HT.

I just don't understand how the encoder/controller gizmos are all connected to be able to do thier stuff when I hit an IR remote button to go from 2.23 to 1.85 to 1.78 and back again.

Andy

[cubesys]

I really like the idea of using a stepper motor as they are accurate and do not need relays or optical encoders to determine when the reach a specific location.

What I am unclear about is how to take the stepper motor kit as mentioned above and create specific points (1.33, 1.66, 1.78, 1.85, 2.35) and have it be controlled via IR.

it seems like the pieces to the puzzle are there, now we just need to connect them.

Itai

[benwillcox]

From what I gather the best and most accurate control system uses a stepper motor, a stepper motor controller, and an optical encoder. I understand how a stepper motor works (is controlled by voltage pulses th rotate a specific amount per pulse). I understand what the encoder does (creates a pulse based on a rotating disk with light/dark bands). The part I don't know enough about is how these things work together, or rather how they are connected together, to make a complete control system. I'm just not an electronics whiz. Does anybody know how this stuff should be integrated that can help us out? I know Don does but he's working on his commercial version and I'm not sure if he is willing to share his secrets - which I totally understand, btw.


Hi Andy,

There are two different approaches to accurate position control - you could use a stepper motor, which as the name suggests rotates in a number of steps, managed by a controller. Therefore, absolute positioning can be achieved by use of a 'home' position sensor, then telling the motor to rotate the correct number of steps needed to get the motor to a specific position.
Alternatively, you could use a standard motor coupled with an encoder, so you drive the motor and count the pulses received which allows you to get to a known position.

One of my previous projects from a couple of years ago was designing an automated curtain controller, and at that time I had decided a stepper motor was the best way forward. I documented some of the system here: http://willcoxonline.com/Curtain/ which may give you a little insight into steppers and how they work. I abandoned the project as I moved on to other things, I decided it was a bit over-engineered for a curtain controller, and the problem is that the control system used to drive a stepper is more complex than a conventional motor.

For somebody who has some basic electronics knowledge, it really is not that hard to design a system that can do everything that is needed to build an automatic masking system.
I've already posted a link to my site which shows a schematic of a microcontroller based system with encoder feedback and RS232 interface. Adding IR control is not a big deal, but it's not something that I'm particularly interested in at this stage, which is why I haven't got that on my control system.

BUT, as GetGray says, it's one thing for an electronics hobbyist to build a system for their own use, but a completely different kettle of fish to build, sell and support a system commercially!

So as far as I can see there are three ways to achieve a motorised masking system:
1) Buy an off the shelf complete screen/masking package for $$$$$
2) Buy a kit that will allow you to construct a masking system from a set of 'black-box' parts
3) Build a system from scratch including electronics etc

Option 1 and 3 already exist (and I've already provided an example schematic and source code for option 3, which shows how the various parts are interconnected, which seems to be the main question at the moment), and it sounds like Don has a system in the works that will satisfy option 2, which would be the most suitable solution for those d-i-y'ers that don't have any electronics knowledge.

So, those that are asking how all these components fit together, I've already shown you an example. But, unless you know how to build it, and by it's very nature it needs technical electronics knowledge to understand, then it's not going to be much help.

To use an analogy, although you can learn how a car works, and can buy wheels, chassis and an engine, unless you have some mechanical knowledge and the tools to put them together, you can't just build a car. (but you might be able to build a kit-car ;-))

Cheers,
Ben

[Gunnar]

Hi! Thanks for sharing this, both the masking systen, and the picaxe automation system. I have no experience with microcontrollers, but it seems like a very interesting project. Is the number of sectors on the encoder determined from the movement pr bit of the mask?

Gunnar

[R Harkness]

Axel

I think Scott is talking about what I was going to try and do.... Basically give up a little screen real estate on either side to have a cutout that would travel very close to the screen while the rest of the material would stay the 1.5" away.... maybe using a piece of plastic or light weight fiber board?

Hopefully I get a drawing together and post it to see what everyone thinks...



That is exactly what I've already planned to do! I want to do a bevelled edge, matching that of the screen frame with the masking board inset into the frame, travelling as close to the screen material as possible. (I'll be using the Carada Masquerade frame for it's' automated vertical masking).

In fact a while back I made
a very crude drawing (my first time using Google's Sketchup). The proportions aren't perfect - the side mask should be the same width as the side of the frame for my design. Also, this does not show the side mask inset into the frame, but rather just beside the frame. The gray attached to
the side of the mask indicates what would be black material, pulled along
by the mask:

http://img441.imageshack.us/img441/5426/maskingsketchfirsttry2ji5.jpg

[benwillcox]

Hi! Thanks for sharing this, both the masking systen, and the picaxe automation system. I have no experience with microcontrollers, but it seems like a very interesting project. Is the number of sectors on the encoder determined from the movement pr bit of the mask?


I experimented with encoder wheels with different numbers of sectors, and found that any higher resolution than the ones you see in the photos would not work with the reflective opto-sensor that I was using. As it worked out, the inertia in that motor & gearbox is the limiting factor so a higher resolution encoder would not give me any extra precision.

Commercially available encoders use a slotted wheel rather than a reflective opto, and give resolutions of hundreds or thousands of pulses per revolution, but of course need would need a suitable drive train to make use of the extra precision.

What I'd like to do now is built a mechanism like Scott's, but fitted with one of those somfy tubular motors coupled with a proper encoder, its just a shame that the motors are so expensive...

Cheers,
Ben

[R Harkness]

BTW,

Most of us would like a side masking system with pre-sets. But if one is willing to give up that convenience, isn't it possible to go with a good automated curtain rod?

From my reading BTX Drapery System 5060 regarded as among the best in terms of reliability, smoothness of operation etc:

http://www.btxinc.com/pages/drap5060.htm

Might that work to pull the side masking boards some of us are talking about?

[benwillcox]

Ok, I was thinking about an idea to fit a somfy tubular motor to Scott's system, whilst slightly simplifying the mechanism...

My idea is to take the mechanism as shown here:
http://home.comcast.net/~scottj0007/theater/MaskingSide_TopView_1.jpg

with a somfy motor fitted to the vertical tubing, but replace the end pulleys with spring balancers (http://www.pvrdirect.co.uk/productInfo.aspx?source=froogle&utm_source=Products&utm_medium=Froogle&catref=ATB0615)instead of running the cables via pulleys back to the vertical tubing.
I'm thinking the advantage of the balancers is that you wouldn't need to adjust the tension using turnbuckles, and eliminate the problem of needing to adjust the diameter of the tubing where the cables feed back using tape.
The spring balancers will provide tension to the material to allow it to be pulled off the tubing and keep it flat and tight.
Unfortunately the spring balancers aren't cheap, and it would need 4 for just a side masking system. Any thoughts?

Cheers,
Ben

[Andy238]

Ben,

Thanks for the link to your curtain project. One of the ad links on the bottom of your page links to a robotics site which was very helpful too. Even had a YouTube video showing a DC motor, motor controller, servo controller, and encoder set up.

Yeah, Somfys would be great. They are really nice and quiet. But just too expensive (for me anyway). I think the cheapest one I saw was at AV-Outlet for $108.

For my implimentation of Scott's design, I was thinking about using counter weights to keep tension on the mask. See my diagrams a ways back (bottom of page 2 I think).
Would that work?

[benwillcox]

For my implimentation of Scott's design, I was thinking about using counter weights to keep tension on the mask. See my diagrams a ways back (bottom of page 2 I think).
Would that work?

Ah yes of course! Yes can't see any reason why it wouldn't work - however you would have to make sure you have enough distance between the bottom of your screen and the floor to give enough drop for the bottom weight to fall.

Another alternative I've thought of is to use a spring loaded retractable roller blind instead of a somfy motor powered one, and then use a conventional geared motor to wind up the cables onto some sort of drum, which then wouldn't need counterweights or spring balancers.
However for this sort of approach (and the weighted one) the motor system would need an electromagnetic brake otherwise the mechanism could retract when the motor is not powered. I understand the somfy unit has an integral brake which is probably part of the reason for it's cost.

Also, going back to the subject of IR control, to add this to a PIC based system I have had a look around, and would probably use something like this: http://www.infraredremote.com/8pindecoder.htm
then use one of the handsets such as these: http://www.infraredremote.com/8keysmall.htm which would give a nice neat solution.

Cheers,
Ben

[HDGTX]

Ok, I was thinking about an idea to fit a somfy tubular motor to Scott's system, whilst slightly simplifying the mechanism...

My idea is to take the mechanism as shown here:
http://home.comcast.net/~scottj0007/theater/MaskingSide_TopView_1.jpg

with a somfy motor fitted to the vertical tubing, but replace the end pulleys with spring balancers (http://www.pvrdirect.co.uk/productInfo.aspx?source=froogle&utm_source=Products&utm_medium=Froogle&catref=ATB0615)instead of running the cables via pulleys back to the vertical tubing.
I'm thinking the advantage of the balancers is that you wouldn't need to adjust the tension using turnbuckles, and eliminate the problem of needing to adjust the diameter of the tubing where the cables feed back using tape.
The spring balancers will provide tension to the material to allow it to be pulled off the tubing and keep it flat and tight.
Unfortunately the spring balancers aren't cheap, and it would need 4 for just a side masking system. Any thoughts?

Cheers,
Ben

Ben, Ran across this web site & McMaster's has "spring balancer" from ~$20 - $33, not sure if these are good enough for what we are talking about (travel: 1.7' to 4.7' & load cap from 1 - 12 lbs). Go to the link below & type in what you are looking for, the cheaper items are a the top of the page: www.mcmaster.com

John

[HDGTX]

I ran across this company's products this evening; Solarbotics. They have two motor controllers that look interesting; "Secret Motor Driver Kit" (#KSMD) for $ 12.50 & the "L298 Compact Driver Dual H Bridge Kit" for $ 17.95(# KCMD). While interesting looking I have no idea how to interface them with IR relays or to a micropressor to tell them where to turn the motors too, that takes someone writing code...

Secret Mtr Driver # KSMD According to what the mfg says, this board can put placed inside a servo motor & convert it to a gearmotor...
http://www.solarbotics.com/products/k_smd/

# KCMD L298 kit for dual motor control
http://www.solarbotics.com/products/k_cmd/

Ben, would this code wheel "Wheel Watcher" setup act enough like an a real encoder to be of help:
http://www.solarbotics.com/products/gmww02/

Their assenbly instructions are even a bit funny.

Can also be purchased from: www.hobbyengineering.com

[Andy238]

Nice find on the Secret Motor Driver, John.

... While interesting looking I have no idea how to interface them with IR relays or to a micropressor to tell them where to turn the motors too, that takes someone writing code...

That's what is so cool about this: http://www.pontech.com/products/sv200bc/index.htm

You can store a program on the chip that will postion the motor using IR input. Follow the link and checkout the manual at the bottom of the page. Excellent examples of programming code in there. From what I gather, you'd connect the board to a PC to fine tune the program (motor position, IR inputs, etc) then store it on the EEPROM chip. It can also control more than one motor.

Go here: http://www.trossenrobotics.com/store/c/2666-DC-Motor-Controllers.aspx?gkw=motor%20controller&gclid=COeIldPRh5ECFQspFQodwjRCFg

and check out the tutorial. That is exactly the setup what we need!... I think. :)

[ScottJ0007]

For my implimentation of Scott's design, I was thinking about using counter weights to keep tension on the mask. See my diagrams a ways back (bottom of page 2 I think).
Would that work?
Another alternative I've thought of is to use a spring loaded retractable roller blind instead of a somfy motor powered one, and then use a conventional geared motor to wind up the cables onto some sort of drum, which then wouldn't need counterweights or spring balancers.

If you motorize the masking, I really like the idea of using positive tension on the masking such as counter weights, spring balancers, or the spring loaded rollers. Those solutions resolve a number of issues I had with my manual system.

However, I suspect that there may be a potential problem with either the counter weight design or the spring balancer design. Both of these designs put tension on the masking by pulling the leading edge of the masking away from the roller. The motor however would be attached directly to the roller and the encoding system would always count the exact position of the roller, not the masking itself. If there is any STRETCH to the masking material, over time the leading edge of the masking might creep towards the source of the tension and the motor controller settings would have to be re-adjusted to account for the stretching of the masking material.

Ben's solution of using a spring loaded retractable roller would not have this problem because the connection to the motor would be from the leading edge of the masking directly to the motor drum via a cable. Any stretch in the masking material would not affect the position of the leading edge of the masking.

I think that Andy's counter weight design could be modified to be a retractable roller design by attaching the weights to a cable that wraps around the roller rather than to the leading edge of the masking. This modification would only require one weight on the roller.

What do you think?

[Andy238]

Hi again. The tutorial is actually here: http://www.youtube.com/watch?v=X4stWDy-bPA "How to Control A DC Motor from Your Computer".

[benwillcox]

Ben, Ran across this web site & McMaster's has "spring balancer" from ~$20 - $33, not sure if these are good enough for what we are talking about (travel: 1.7' to 4.7' & load cap from 1 - 12 lbs). Go to the link below & type in what you are looking for, the cheaper items are a the top of the page: www.mcmaster.com


Yes that's the kind of thing I was thinking about. I actually found some on ebay UK for £6.50 each, which is a much better price, and has adjustable tension.

I ran across this company's products this evening; Solarbotics. They have two motor controllers that look interesting; "Secret Motor Driver Kit" (#KSMD) for $ 12.50 & the "L298 Compact Driver Dual H Bridge Kit" for $ 17.95(# KCMD). While interesting looking I have no idea how to interface them with IR relays or to a micropressor to tell them where to turn the motors too, that takes someone writing code...

Secret Mtr Driver # KSMD According to what the mfg says, this board can put placed inside a servo motor & convert it to a gearmotor...
http://www.solarbotics.com/products/k_smd/

# KCMD L298 kit for dual motor control
http://www.solarbotics.com/products/k_cmd/

Ben, would this code wheel "Wheel Watcher" setup act enough like an a real encoder to be of help:
http://www.solarbotics.com/products/gmww02/


Ok the H-bridge kit is a way to drive a DC motor in forward or reverse, by using low-level control signals. This could also be done with relays as an alternative.

The secret motor driver is designed for Radio Controlled model type servo motors, which I think would probably not have enough torque for this application. That encoder wheel is pretty much exactly the type of thing that we need though, although fully enclosed types are available elsewhere which may be a bit more robust.



That's what is so cool about this: http://www.pontech.com/products/sv200bc/index.htm

You can store a program on the chip that will postion the motor using IR input. Follow the link and checkout the manual at the bottom of the page. Excellent examples of programming code in there. From what I gather, you'd connect the board to a PC to fine tune the program (motor position, IR inputs, etc) then store it on the EEPROM chip. It can also control more than one motor.


The problem with this controller is that it is designed for use with servo motors. This type of motor uses a different type of feedback mechanism, that gives absolute positioning of a shaft. However, the shaft does not rotate continuously, and usually has a max rotation of less than 360 degrees (for RC type servos anyway) so you can basically just set a desired angle on a shaft, which wouldn't be useful for this type of application

If you motorize the masking, I really like the idea of using positive tension on the masking such as counter weights, spring balancers, or the spring loaded rollers. Those solutions resolve a number of issues I had with my manual system.

However, I suspect that there may be a potential problem with either the counter weight design or the spring balancer design. Both of these designs put tension on the masking by pulling the leading edge of the masking away from the roller. The motor however would be attached directly to the roller and the encoding system would always count the exact position of the roller, not the masking itself. If there is any STRETCH to the masking material, over time the leading edge of the masking might creep towards the source of the tension and the motor controller settings would have to be re-adjusted to account for the stretching of the masking material.

Ben's solution of using a spring loaded retractable roller would not have this problem because the connection to the motor would be from the leading edge of the masking directly to the motor drum via a cable. Any stretch in the masking material would not affect the position of the leading edge of the masking.

I think that Andy's counter weight design could be modified to be a retractable roller design by attaching the weights to a cable that wraps around the roller rather than to the leading edge of the masking. This modification would only require one weight on the roller.

What do you think?

I think you have a very good point about the fabric stretching with that first design, and that could definately be a problem, as you describe.
I can't quite picture what you mean about wrapping a cable round the roller with a counterweight though - what would be pulling the leading edge of the masking in this case?

Lots of good ideas coming out now, we just need to put the right ones together!

Cheers,
Ben

[Andy238]

The problem with this controller is that it is designed for use with servo motors. This type of motor uses a different type of feedback mechanism, that gives absolute positioning of a shaft. However, the shaft does not rotate continuously, and usually has a max rotation of less than 360 degrees (for RC type servos anyway) so you can basically just set a desired angle on a shaft, which wouldn't be useful for this type of application

Yes it is a servo controller. But, you can use a PWM controller with a DC motor. Check out the tutorial in the YouTube link I posted. A servo motor can also be easily modded to run continously and provide high torque. ;)

Mmmm, I'm not sold on the stretching being a big problem. I mean, we're not pulling against a lot of resistance (especially if we use bearings) and the counter-weight or wrapped cable is only keeping it taught. We're not really stretching it that tight. IMHO anyway.

[benwillcox]

Mmmm, I'm not sold on the stretching being a big problem. I mean, we're not pulling against a lot of resistance (especially if we use bearings) and the counter-weight or wrapped cable is only keeping it taught. We're not really stretching it that tight. IMHO anyway.

I guess it depends on the material used, and the amount of force applied to keep the material taught - I think this is the sort of stuff that can only really be proven by building a prototype!

Cheers,
Ben

[Andy238]

Agreed. I guess it would depend on say, if you use velvet or an AT material like GOM. Those fabrics probably won't stretch the same.

Ok, who's going to build the first prototype? :D

[R Harkness]

Still looking for an answer for my question, quoted below. Thanks:

BTW,

Most of us would like a side masking system with pre-sets. But if one is willing to give up that convenience, isn't it possible to go with a good automated curtain rod?

From my reading BTX Drapery System 5060 regarded as among the best in terms of reliability, smoothness of operation etc:

http://www.btxinc.com/pages/drap5060.htm

Might that work to pull the side masking boards some of us are talking about?

[Andy238]

Hey Rich,

Sure. There are several AVSers who use a drape system to move masking panels. You're right too, BTX is one of the better systems. I think Makita is up there too. Do a search for "masking" in the dedicated theater construction forum as well as the 2.35 CIH forum and you should find some threads about it.

I just don't have the room on the sides of my screen to use this method. If I did, I probably would. It's pretty easy to incorporate.

Cheers,
Andy

[R Harkness]

Thanks Andy.

[HDGTX]

Ben, Is this what you mean by spring loade roller ? Here is a product from "Rollease" for roller shades....

http://rollease.com/SpringAssist.htm

[Andy238]

You can buy the SpringAssist here: http://www.av-outlet.com/en-us/dept_511.html
At the bottom of the page. Cheap too!

[Andy238]

Now that I think about it more. That little gizmo would be great since it'll fit right into the 1.5" diameter aluminum tubes AV-Outlet sells too! Hmmmm.....

[benwillcox]

Ben, Is this what you mean by spring loade roller ? Here is a product from "Rollease" for roller shades....

http://rollease.com/SpringAssist.htm

Yes that's the sort of thing I was thinking of.

Also, have a look at this pdf here: http://www.silentgliss.com.au/doc/doc_download.cfm?29A420EB306E2C0BE350AB142A87AE84

There's quite a few different blind systems there that might be suitable, especially the Tess 100 system.

Edit: In fact, the Tess 120 looks perfect, as it incorporates side guides which would mean it could be directly used in the orientation needed for side masking: http://www.windowworldhi.com/Specifications/GuthrieDouglas/Tess%20120%20data.pdf
Can't seem to find any prices anywhere though!
Ben

[Andy238]

Boy, wouldn't that system be sweet. Almst plug & Play.
Betcha they use Somfy motors... and you know what that mean$. :D

[HDGTX]

Ran across this company, GoelstAmerica, someone may have mentioned them in regards to skylight shades. Maybe this would work for those who would want to use curtains as masks. Below is a pdf link for their 6200 series 24V motorized drapery rod, their lit says it has a variable speed motor, soft launching / docking & up to 5 presets programable. Of course there is no pricing on their web site Their US office is near Atlanata. Take a look: :)

http://goelstamerica.com/fileadmin/product-pdfs/6200%20UK.pdf

John

[R Harkness]

Ran across this company, GoelstAmerica, someone may have mentioned them in regards to skylight shades. Maybe this would work for those who would want to use curtains as masks. Below is a pdf link for their 6200 series 24V motorized drapery rod, their lit says it has a variable speed motor, soft launching / docking & up to 5 presets programable. Of course there is no pricing on their web site Their US office is near Atlanata. Take a look: :)

http://goelstamerica.com/fileadmin/product-pdfs/6200%20UK.pdf

John


OMG that's perfect! Exactly what I"m looking for! I'm one of the few who will be using a variable image size, 4 way masking (and not merely CIH) so those pre-sets are a god-send.

I only hope it isn't going to be as expensive as it looks :eek:

Anyway, I've contacted the company and they only do quotes via email, so I'll
be sending an email to check them out.

Thanks very much!

[Axel]

....
Anyway, I've contacted the company and they only do quotes via email, so I'll
be sending an email to check them out.
...

Please let us know what you find out.

TIA!
____
Axel

[Audiodynamics]

When I was a kid, I used to use magnetic "Reed Switches" in my projects as limit switches. You use a magnet on the moving part and the reed switch can be mounted on an adjustment plate. Magnetic alarm switches, used on doors and windows are a good example of this type of system.

What if you mounted a magnet or magnets on your cable with heat shrink tubing, far enough away from the pulleys not to interfere with them. And you mount the limit switches on sliding adjustment plates, allowing you to set your stops or limits.

Below, is a radio shack link to the type of switch available at a low cost. You can take the magnet out of the plastic case and heat shrink it to the cable assembly and use the reed switch housing as-is. The switch housing already has screw holes for mounting.

http://www.radioshack.com/product/index.jsp?productId=2419298&cp=2032060.2032330.2032348&parentPage=family

Actually, you can use the normally closed contacts of the switch and when the magnet activates the reed relay, power is cut. You then re-apply power when needed, which overrides or bypasses the limit switch.

Control of your motor assembly can all be accomplished with simple relays which cut voltage continuity to the motor, stopping its rotation at your preset limits. Everything can be either linked to your projector's trigger outputs or controlled with Xantech IR activated relays.

I know this concept is not a very elegant solution, but sometimes inexpensive and simple implementation is the best means to an end.

[R Harkness]

Ran across this company, GoelstAmerica, someone may have mentioned them in regards to skylight shades. Maybe this would work for those who would want to use curtains as masks. Below is a pdf link for their 6200 series 24V motorized drapery rod, their lit says it has a variable speed motor, soft launching / docking & up to 5 presets programable. Of course there is no pricing on their web site Their US office is near Atlanata. Take a look: :)

http://goelstamerica.com/fileadmin/product-pdfs/6200%20UK.pdf

John


Hey folks. If I wanted to use the above product, with the 5 presets used for
variable side masking widths, would you suggest I go for the IR or the RF remote control option?

Ideally I would like my RTI T3 universal remote (which can do both IR and RF, and works with a universal RP6 controller) to have pre-programmed image width selections.

Thanks.

[HDGTX]

Hi Audiodynamics,

Thanks for the info, simple is always a good plan. I have
a couple of questions;

Does it take special wiring to start the motor once again, after it has been shut off by the first reed swt ?

Will each reed switch position require a seperate relay to break the current flow for each new AR stop ?

Would someone sketch this out and display it for us ?

Do you think proxmity switches would work in the same way as a reed swt ?
-------------------------------------------

Rharkenss, do let us know what they tell you. They sent me a pdf of the instruction maual. I can email that, if somone wants it, just PM me.

John

[R Harkness]

Well the quote for the GoelstAmerica 6200 motorized drapery system was actually pretty good, comparatively and all things considered.

The quotes I was getting for a 160" BTX BTX Drapery System 5060 were closer to $2,000. Whereas the quotes for the same size Goelst system is several hundred dollars less, and then after the discount for my company (you might have to have a company, or be an installer to purchase) it's lowered another $440 more!

Given the Goelst system does even more than the BTX system, especially those luscious
5 pre-sets and apparent ease of installation, I may have found my masking/curtain system!

Cheers,

[Axel]

Contgrats Rich!
Concerning RF vs. IR. I found that in most cases RF communication protocols, unlike IR, can not be learned by universal remote controls. So in short, I would definitely verify that RF is in fact an option for you, in case you went that route.
____
Axel

[Andy238]

Awesome, Rich! I contacted Goelst too. The main company won't quote or sell to individuals. I asked for info on just the motor kit, 6200-00 Motor Set and the 6220 Drive Belt.

Their reply:

"I’m sorry, but I cannot quote directly to an individual. If you will let me know where you are located, I’ll refer you to a dealer. However, we normally, do not sell components to end users, only assembled products."

I'm still waiting for the dealer info.

Rich, can you get a quote on the motor set and drive belt?

Andy

[Andy238]

When I was a kid, I used to use magnetic "Reed Switches" in my projects as limit switches. You use a magnet on the moving part and the reed switch can be mounted on an adjustment plate. Magnetic alarm switches, used on doors and windows are a good example of this type of system.

What if you mounted a magnet or magnets on your cable with heat shrink tubing, far enough away from the pulleys not to interfere with them. And you mount the limit switches on sliding adjustment plates, allowing you to set your stops or limits.

Below, is a radio shack link to the type of switch available at a low cost. You can take the magnet out of the plastic case and heat shrink it to the cable assembly and use the reed switch housing as-is. The switch housing already has screw holes for mounting.

http://www.radioshack.com/product/index.jsp?productId=2419298&cp=2032060.2032330.2032348&parentPage=family

Actually, you can use the normally closed contacts of the switch and when the magnet activates the reed relay, power is cut. You then re-apply power when needed, which overrides or bypasses the limit switch.

Control of your motor assembly can all be accomplished with simple relays which cut voltage continuity to the motor, stopping its rotation at your preset limits. Everything can be either linked to your projector's trigger outputs or controlled with Xantech IR activated relays.

I know this concept is not a very elegant solution, but sometimes inexpensive and simple implementation is the best means to an end.

A guy a while back, Bob Trinanes, was working on that very thing. Here is the archived thread --> http://archive2.avsforum.com/avs-vb/showthread.php?s=&threadid=350149

Hey! Archive2 is back!

Anyway, I think he had some schematic on the relay setup he used. Check it out.

Andy

[Audiodynamics]

Hi Audiodynamics,

Thanks for the info, simple is always a good plan. I have
a couple of questions;

Does it take special wiring to start the motor once again, after it has been shut off by the first reed swt ?

Will each reed switch position require a seperate relay to break the current flow for each new AR stop ?

Would someone sketch this out and display it for us ?

Do you think proxmity switches would work in the same way as a reed swt ?
-------------------------------------------

Rharkenss, do let us know what they tell you. They sent me a pdf of the instruction maual. I can email that, if somone wants it, just PM me.

John


"Does it take special wiring to start the motor once again, after it has been shut off by the first reed swt ?"

No special wiring is required. This entire control system can be built without the aid of any solid state circuitry.


"Will each reed switch position require a seperate relay to break the current flow for each new AR stop ?"

NO and YES. It depends on the current draw of the motor. If the motor draws more current than the reed switch contacts are capable of handling, then the reed switch contacts will burn out. In that case, a second relay will be necessary for current handling capability. In the worst case, two relays will be required to control one masking motor. Three position masking systems (Retracted, 4:3 and 16:9) will require three reed limit switches and may require three relays, again depending on the motor's current draw.


Do you think proxmity switches would work in the same way as a reed swt ?

There are several thypes of proximity switches. Ex: photoelectric, inductive, ultrasonic, binary, etc. The magnetic reed switch is a proximity switch in a simple form.


Here's an overview of my proposed control system:

A relay is a simple electro-mechanical switch. Applying voltage to the relay coil moves the relay contacts. The relay contacts act as a switch passing voltage from an external power supply to the masking motor, turning the motor on or off and reversing the motor's direction.

This system can be IR controlled with a Xantech IR activated relay or can simply be connected to the projector trigger. Using the PJ's trigger is simplicity in itself.


The projector trigger can be used to activate the coil of a Double Pole Double Throw relay (DPDT). In many cases, the PJ trigger may not have enough current to activate a relay coil. In this case, a solid state circuit can be used to activate the relay coil. Even easier, a special relay called a sensitive relay is designed for this purpose.

Caution: DO NOT attempt to use the PJ's trigger output to power the motor.


A. When the PJ's trigger is active, the relay can apply power to the masking motor.

B. When the masking has extended to a preset point where the magnetic reed limit switch is activated, the limit switch opens the circuit stopping the motor.

C. When the PJ's trigger is then deactivated, the contacts of the DPDT relay in it's off state can provide power to overide the limit switch, re-starting the motor and in turn moving the masking system back to it's retracted position. A second limit switch will prevent the masking from retracting too far.

D. Basically, two limit switches are required per masking panel. One limit switch sets the fully extended position and the second limit switch sets the fully retracted position. Three position masking systems (2.35 AR when retracted, 4:3 and 16:9) will require three reed limit switches (a limit switch for each position) and may require three relays, again depending on the motor's current draw.

E. Utilizing a DC motor in automating this DIY masking system will simplify things greatly. With a DC motor, the same DPDT relay which is activated by the PJ's trigger, if wired correctly, can reverse voltage polarity to the masking motor. This will reverse the motor's direction, returning the masking system to it's fully retracted position.

This concept is actually very simple to assemble, wire and implement. It should also be very reliable.

I'm happy to assist the first guinea pig who wishes to implement this proposed control system.

EDIT: The number of programmable trigger outputs your PJ or Video Scalar offers will determine whether or not you can control a three position masking system (2.35 AR when retracted, 4:3 and 16:9). You'll need two trigger outputs for three positions. If you only want a two position masking system (16:9 / 4:3) then one trigger will suffice. If you don't have enough trigger outputs, then the Xantech IR Relay block will provide complete control.

[Audiodynamics]

A guy a while back, Bob Trinanes, was working on that very thing. Here is the archived thread --> http://archive2.avsforum.com/avs-vb/showthread.php?s=&threadid=350149

Hey! Archive2 is back!

Anyway, I think he had some schematic on the relay setup he used. Check it out.

Andy

Good Find Andy!

I just read through Bob's DIY electric masking thread. Fantastic Design! Bob's control system is very similar to what I've proposed. I'm often amazed at the level of creativity and skill exhibited by a lot of you folks here at AVS!

I solve my client's issues by designing custom solutions for high end applications. My hats off to all you guys who tackle the tough jobs yourself and to those who have at least tried. And to the OP Scott, congratulations on the design of your great DIY masking system. The simplicity makes it that much more attractive.

My suggested automation control is a low cost, simple alternative that works seamlessly with the PJ's or video scalar's 12 vdc triggers. And it should easily be retrofittable to the OP's DIY masking system.

[HDGTX]

Got an odd question, was wondering if automobile timing tape could be used for an optical encoder to read the revolutions of a screen motor when wrapped around a spool or pulley ?

http://www.speedwaymotors.com/pl/243,5433_MSD-Timing-Tapes.html

Did you look at the "Marvomatic" post mentioned earlier, where the fellow had a home made striped tape wrapped around the roller of his Stewart screen, being read by an optical device ?

Is there some relationship in spacing or thickness of the black & white lines so that a reader can see it properly ?
Does it need to match in some way to the what the motor control board might be looking for as steps or pulses ?

Just wondering?

John

[HDGTX]

Hi Audiodynamics,

I did not see a "IR relay block" on Xantech's web site, did find a #CC12 a "remote relay module". Is the relay block called something else & do you have a part number ?

I am very interested in your approach, simple is great. I am in the planning stage, no projector or screen as yet.

I plan to use a DC motor for horiz & verticle masking on a
4' x 8' screen and to have 2.35, 1.78, 1,85 & 4:3 AR's and maual adjustment (tweeking). What type of DC motor would work best with your limit switch / relay design; a gearmotor or stepper (bipolar, unipolar) ?

Is there an RPM target recommended for the motors, is 24 RPM too slow or 80 too fast ?

Don from HTIQ recommended a torque rating of 150oz-ins (thats a tough motor to find).

In your experience, how close do the magnets need to be to the reed switches to trip them ?

John

[Andy238]

Hey all,

In case you're having trouble seeing Bob Trinanes' old relay wiring schematics here they are. I think I"m going to go his route and use his original wiring diagram (#1). Very simple. ;)

Andy

[Audiodynamics]

Hi Audiodynamics,

I did not see a "IR relay block" on Xantech's web site, did find a #CC12 a "remote relay module". Is the relay block called something else & do you have a part number ?

I am very interested in your approach, simple is great. I am in the planning stage, no projector or screen as yet.

I plan to use a DC motor