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I would think this would be the easiest methiod of implementation. Eliminate the color wheel, which i think is kind of an absurd solution anyway. (A part rotating inside with mass has to create both noise and stress on bearings and motors, which dont belong in solid state components) Lasers can be pulsed on and off fast enough to elimate rainbow, and if the dmd can switch alignments in the mhz frequencies, problem solved!

Also the removal of the bulb would reduce (eliminate?) the need for a fan, allowing for a totally sealed, silent unit. No more dust!

Im not an engineer or even a videophile, i own a L300U, but all the interesting discussions seem to occur in this forum. (At least until the third page where it turns into arguments about who said what and there intentions in saying so :) )

Is this solution infeasable for a reason i haven't considered?
 

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Quote:
Originally posted by price3
I would think this would be the easiest methiod of implementation. Eliminate the color wheel, which i think is kind of an absurd solution anyway. (A part rotating inside with mass has to create both noise and stress on bearings and motors, which dont belong in solid state components)
[
If that's your criteria - then you'd have to dispense with the DLP, aka DMD chip. The DMD chip is basically

a mechanical device - little mirrors with mass and bearings that oscillate instead of rotating all with the

accompanying stresses.

Quote:
]

Lasers can be pulsed on and off fast enough to elimate rainbow, and if the dmd can switch alignments in the mhz frequencies, problem solved!
[
A mechanical device switching at megahertz frequencies? That's thousands of times faster than

anything yet achieved., Will also shorten the lifetime by a factor of a thousand vis-a-vis the state of the art.

Quote:


Also the removal of the bulb would reduce (eliminate?) the need for a fan, allowing for a totally sealed, silent unit. No more dust!
You think lasers don't produce heat? Lasers as a class are notoriously inefficient. Solid state lasers are more

efficient than crystal or gas lasers - but you are still going to need a cooling fan.

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]

Im not an engineer
Obviously!

Quote:


or even a videophile, i own a L300U, but all the interesting discussions seem to occur in this forum. (At least until the third page where it turns into arguments about who said what and there intentions in saying so :) )

Is this solution infeasable for a reason i haven't considered?
Yes - you've made a number of assumptions as to how the technology works that are unwarranted.
 

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That was brutal Dr. Greg. I now know why I am less than enamored every time i get stuck going to an event in the physics department. At least the good Dr's. in Mechanical Engineering are willing to teach and not abuse. I truly think you physics guys have issues partially because of ...........never mind you wont listen anyways, you all ready know that you are right and i am just some idiot wandering around in cyber space.
 

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Mr. Dr. Gregory Greenman...Physicist...


Must you be so condescending in your posts?


While your expertise is welcome, the spirit of your posts renders your comments fruitless and of little value to all members of AVS--both informed and uninformed alike. Your contributions would be better received if you could learn to characterize them in a helpful and teaching-oriented manner. Regarding posts on this forum, it is the lack of common courtosy that is the least tolerable, not comments that err in technical inaccuracies.


Despite some technical inaccuracies, price3 points towards some good solutions that would be better fine-tuned than discarded whole.


For instance, price3 discusses the benefit of losing the color wheel. He's right. And as you say laser could take one even further by allowing one to leave the DMD behind as well. If that were acheived, then there would be no need for alternating RGB sequencing which means that the lasers could burn in constant-on fashion giving one the benefits of current 3-chip designs.


price3 may have more going for his notion than even arrogant AVS posters may concede. It seems that JVC is experimenting with lasers in tandem with their LCOS chips. I'm not certain how this is being accomplished or what the advantages are replacing the light-source of the bulb with laser light and how this is able to "scan" the LCOS chips effectively...but the engineers at JVC seem to find some strength in combining the light-source of laser with the imaging device of their LCOS chips in the prototypical designs that are under development.
 

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by the way dr greg i have helped design an extruded aluminum heat sink which has three water channels in it that acts as a fully contained thermodynamic heat pump, being self contained the rise in pressure from the heat causes the water to circulate, anyways i am sure you understand the concept, and yes it is cooling a small laser with no fan.
 

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Whoa,

somebody rename the thread:

"The Dr. Gregory Greenman, Physicist Bashing thread"



Dr. Andreas, Yield Enhancer
 

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I forgot this:

:)
 

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"The DMD chip is basically a mechanical device - little mirrors with mass and bearings that oscillate instead of rotating all with the accompanying stresses."


DMD's do not have bearings, which imply relative motion between separate parts. They have flexures, where motion occurs by bending and/or twisting of the support material (I just looked at TI's animated demo, from which it appears to be the latter).


Mechanical engineers do not consider flexures to be moving parts because there are no clearances or wear, although fatigue life from stress cycling must be considered.


On the general topic of the thread, replacing a DLP pj's light source with a laser doesn't seem to have much to reccommend it, unless it gives more lumen/W for the same or less money.


The latter isn't likely, since you'd need R, G, and B lasers.


It seems to make a lot more sense to relace the DMD with another MEM's device to scan the laser directly onto the screen while modulating it's intensity.


This makes achieving high CR much easier, since it essentially mimics CRT operation, and makes the optical system much simpler, since a whole (I think teh Marantz has a dozen elements) bunch of light-eating lenses aren't needed to focus the beam.


This
 

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Quote:
It seems to make a lot more sense to relace the DMD with another MEM's device to scan the laser directly onto the screen while modulating it's intensity.
Which is basically the direction GLV is taking.
 

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Does the GLV device also do the scanning as well, or just the on/off (reflective/absorptive) functionality with a standard mirror assembly doing the scanning?
 

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The glv device modulates the intensity of the laser. The laser will be constantly on and modulated by the glv.


Why not r, g and b lasers instead of a lamp for a dlp projector? If the lasers are long lasting, energy efficient and gives great color saturation they would be useful. Are they or will they be all that? I do not know what happens with a laser beam if you diffuse it to hit an entire dmd.
 

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I don't think the GLV device does any scanning. It is done after by some type of optical manipulation. Could be some type of mirror.


Mattias:


Doesn't a laser in a GLV device have to be diffused to cover the whole GLV array?
 

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I thought the GLV "ribbon" pivoted to "scan" the laser light from left to right.


You may be right about it difusing accross the entire ribbon at once.


-dave
 

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Quote:
Originally posted by DaViD Boulet
Mr. Dr. Gregory Greenman...Physicist...


Must you be so condescending in your posts?
I think the original post is condescending - the color wheel is "absurd", for example.


The state of the art of projectors is the way it is for good reason. It's easy to hand-wave and say that all one has

to do is have megahertz framing rates and all problems are solved. However, think what that implies.


First, DLPs [ DMDs ] modulate the intensity of the light via a "duty cycle" - that is the mirror is either on/off - so the DLP

chip oscillates with 60% of its time in the on position and 40% off in order to realize a 60% light intensity. Therefore,

the mirrors are moving much faster than the framing rate.


So if we have megahertz framing rates - then the mirrors are moving on the order of 100s of megahertz

or even gigahertz. The thought of something flexing that fast really gives one pause.


We are all familiar with laser pointer devices - and they do run cool - but they are extremely low power. Lasers

do not magically solve the cooling problems. Yes, one can always cool the laser - I work for a lab that developed

"microchannel technology" to cool lasers.


The original post seemed to me to be bashing the designers of current projectors - if only the engineers

would get rid of "absurd" color wheels, and if they used lasers instead these dumb arc lamps - then we'd have

much better products.


The point of my post was that there are reasons - technical reasons, cost-point reasons, etc. that make

projectors what they are today. Many think that it's so simple - if only the engineers would get a clue.


I pointed out - admittedly bluntly - that that's not the case.
 

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everyone already knows that engineers are worthless, even us engineers realize it.............. actually the problem is more with marketing and the bean counters.
 

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NOW,


I want everyone in this thread to hug and shake hands . . . and if you don't have something nice to say, don't say anything at all.


MOM :)
 

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I think Gregory's defense is a fair one. The tone was set by the first post, not by Gregory's response.


Look, the poster admits up front that he's not an engineer. And yet in the same paragraph, he has the cojones to claim that the color wheel is an "absurd" solution and give us engineering-related reasons why that is so?


Oh yes, and let's look at that reason: "A part rotating inside with mass has to create both noise and stress on bearings and motors, which dont belong in solid state components." I see. So does that make cooling fans an "absurd solution" as well?


Look, the color wheel is not a hack. It is a design compromise with advantages and disadvantages. The disadvantages are well known, but in return you get perfect convergence---something a three-chip projector can never achieve---a greatly simplified optical path, reduced overall cost, and higher contrast than any three-chipper currently available.
 

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Quote:
I think the original post is condescending - the color wheel is "absurd", for example.
I'm sure all the colorwheels out there are rightly offended. :)


In all fairness, even TI engineers regard the color-wheel as a necessary-evil to achieve single-chip performance. Hence all the work to speed them up, add more dark segments to reduce dithering, and come up with new approaches like SCR. All these design goals are an attempt to ameliorate the ills associated with the color-wheel since the expense of 3-chip deisgns are prohibitive at most consumer price-points.


I doubt that most engineers would have taken personal offense at the phrase:

Quote:
Eliminate the color wheel, which i think is kind of an absurd solution anyway. (A part rotating inside with mass has to create both noise and stress on bearings and motors, which dont belong in solid state components)
as they likely share in the sentiment to some degree themselves and don't have a love-affair with the device. After all, the color wheel is a means to an end...not the core around which DLP technology is built.


Price3's discussion of laser light was not delivered in any way that critically bashed bulb-based designs, he was merely musing a potential improvement to the light source as indeed many folks working at TI, JVC, and Sony are currently researching.


In any case, price3's comments were clearly not directed personally to any one person or even a group of people (not even TI engineers), very unlike your comments which were plainly rude and directed personally back at him. No one needs to be a Physicist with an egineering degree to determine the difference.

Quote:
The point of my post was that there are reasons - technical reasons, cost-point reasons, etc. that make

projectors what they are today. Many think that it's so simple - if only the engineers would get a clue.
That's a very valid point. If you can continue to express yourself in this manner you'll garner my full respect.

Quote:
Oh yes, and let's look at that reason: "A part rotating inside with mass has to create both noise and stress on bearings and motors, which dont belong in solid state components." I see. So does that make cooling fans an "absurd solution" as well?
Actually, his comments about eliminating the need for air-flow cooling go in exactly that direction. Gotta give him points for consistency! :)

Quote:
Look, the color wheel is not a hack. It is a design compromise with advantages and disadvantages. The disadvantages are well known, but in return you get perfect convergence---something a three-chip projector can never achieve---a greatly simplified optical path, reduced overall cost, and higher contrast than any three-chipper currently available.
Again a very valid point and one that resonates with what Gregory was trying to communicate. I don't see him every deriding the advantages of a single-chip design, only the irony of depending on a mechanical spinning wheel to make an otherwise "solid state" digital device work. Perhaps his wording was too strong with the descriptor "absurd" ("design compromise" is a much better choice of words), but it hardly creates an "offense" to anyone worth the rude and personal put-down that he received in reply.
 

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Quote:
Actually, his comments about eliminating the need for air-flow cooling go in exactly that direction.
Except that his comments do not go in that direction---because his solution would likely generate more heat, not less.
Quote:
Perhaps his wording was too strong with the descriptor "absurd" ("design compromise" is a much better choice of words), but it hardly creates an "offense" to anyone worth the rude and personal put-down that he received in reply.
Well, let's see. When I read Dr. Freeman's post, the only offensive thing I see is possibly his one-word reply, "Obviously!" to price3's claim he's not an engineer. Take that out and the rest sounds very reasonable to me. So if you're willing to overlook price3's poor choice of a single word, I think it's fair for you do the same for Dr. Greg. In fact, while I do find Dr. Greg to be a bit, well, rough at times, in this case you've written more personal criticism on this thread than anyone else---if we care to count words.
 
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