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How does DLP-Link work ?

30752 Views 32 Replies 11 Participants Last post by  Augerhandle
Tried finding an answer using search, with little luck - though I found links to how the checkerboard 3D on DLP works.


So, how does DLP-Link work ? Esp. with front projectors.
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I'm sure others will chime in with a more detailed answer, but very basically: a white flash is sent to the screen in between the content, and the active glasses use this to sync the shutters.

Quote:
Originally Posted by thebard /forum/post/20849642


I'm sure others will chime in with a more detailed answer, but very basically: a white flash is sent to the screen in between the content, and the active glasses use this to sync the shutters.

That sounds simple enough. So that would also mean the syncing should be fast as there are so many opportunities per second to sync ?
Well, in theory, it should sync exactly 120 times per second (the refresh rate of a 3d signal).


Advatnages of DLP over rf/ir setups: No separate emitter needed; glasses can be slightly cheaper than similar ir or rf glasses; reasonable compatibility across several manufacturers; won't interfere with remote controls or wifi products.


Disadvantages: Use limited to compatible dlp-tech displays; some people complain of color shift due to white flash; usually cannot tune delay/duty cycle; need line-of-sight or sync is lost (true of ir as well, but not rf).
I hope you are not going to use DirecTV with that setup. Unless something has changed, checkerboard is NOT supported by D* receivers.

Quote:
Originally Posted by machavez00 /forum/post/20852842


I hope you are not going to use DirecTV with that setup. Unless something has changed, checkerboard is NOT supported by D* receivers.

The converter for most all standard 3D sources to Checkerboard are relatively inexpensive.


The OP did mention front projection specifically though.
Front DLP projectors are not checkerboard.

Quote:
Originally Posted by machavez00 /forum/post/20852842


I hope you are not going to use DirecTV with that setup. Unless something has changed, checkerboard is NOT supported by D* receivers.

No - I'm stuck with D* for now. So, no 3D unless Charlie changes his mind.

Quote:
Originally Posted by aoaoo0 /forum/post/20851996


Because the DLP imaging chip is so fast, it is able to project two images on the screen at one time to create the 3D image viewed through the active glasses.

This is not really correct. The L/R images are displayed in sequence, alternating L/R 120 times per second, in sync with the shutters on the glasses. It's very fast, but it's not "at one time". If the two views were displayed simultaneously with active glasses, it would ruin the 3d effect.

Quote:
Originally Posted by DenisG /forum/post/20852902


Front DLP projectors are not checkerboard.

Upon quick search FPs seem to use frame sequential. RPs use Checkerboard. DLP-Link works with both of them because of the full white image "signal" shown between frames ?


So, looks like FPs potentially offer better resolution than checkerboard RPs. FPs can be 1080 for each eye, depending on the source. I like this already
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I use Direct TV 3D with my Checkerboard only Mitsu DLP as well as my frame seq. FP in the theater.


I do have converters for both to make this happen though.


Both systems use the DLP link glasses.

Quote:
Originally Posted by thebard /forum/post/20853033


This is not really correct. The L/R images are displayed in sequence, alternating L/R 120 times per second, in sync with the shutters on the glasses. It's very fast, but it's not "at one time". If the two views were displayed simultaneously with active glasses, it would ruin the 3d effect.

Actually he is just quoting TI.

http://www.dlp.com/projector/dlp-inn.../dlp-link.aspx

Quote:
Because the DLP imaging chip is so fast, it is able to project two images on the screen at one time to create the 3D image viewed through the active glasses. But, in addition to the two images on the screen, the DLP chip also sends additional data to the glasses in-between each frame of video. This is how the projector communicates with the DLP link enabled active glasses. This ingenious transmission technique makes data emitters obsolete and eliminates the need to install and position emitters. This saves you time and money and makes setup of a 3D Ready DLP projector quick and easy.

Quote:
Originally Posted by evnow /forum/post/20853269


Actually he is just quoting TI.

http://www.dlp.com/projector/dlp-inn.../dlp-link.aspx

May be so... but still not correct!


Shame on you, Texas Instruments...

Quote:
Originally Posted by thebard /forum/post/20853278


May be so... but still not correct!


Shame on you, Texas Instruments...

That depends on your definition of "at one time" ;-)


Afterall, DLP is time multiplexed and as such one could argue at any one time it isn't even displaying a 1080p color image even in 2D.
Here's a video I shot at 600fps that shows what goes on:



The DLP Link flash is blue (it can be red on other TVs), probably because white is more complicated, taking 3 times as long to produce.

Quote:
Originally Posted by cakefoo /forum/post/20860668


Here's a video I shot at 600fps that shows what goes on:


..


The DLP Link flash is blue, probably because white is more complicated, taking 3 times as long to produce.

Thanks for this.


Why does the video have top & bottom lightup separately ? Is that how the Mitsu DMD work (all the 540p wobbled to 1080p ?).
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It's actually the crosstalk test image from this thread displayed in 3D mode. The image for the left eye is black on the bottom half with numbers on the top half, while the right eye image is the opposite.

Quote:
Originally Posted by cakefoo /forum/post/20860668


The DLP Link flash is blue, probably because white is more complicated, taking 3 times as long to produce.

What color tint do you get on your set in 3D mode? On my Samsung it is hot red so my guess is the DLP flash is a different color on my set.

Quote:
Originally Posted by nickels55 /forum/post/20869652


What color tint do you get on your set in 3D mode? On my Samsung it is hot red so my guess is the DLP flash is a different color on my set.

Oh, I see. Mine is blue.


I wonder would the same glasses work on both TVs?
Interesting in that I have always read its' a white flash?


Not sure, but the same glasses work on my Mitsu and my 720p Front Projector.
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