LCD Shutter Glasses Patterns

[Neil]

Hi Guys!

We are getting set to produce a series of videos about the available 3D equipment on the market and how they work. However, I have a question about LCD shutter glasses and the modes they operate in. These are the modes I know about:

1. Left, Right, Left, Right
2. Left, BLACK (both left and right are black), Right, BLACK, Left, BLACK, etc.

Are the above patterns correct? Are there other patterns too?

Regards,
Neil

[tritosine5G]

The "black frame inserted" 2nd variant is only necessary with LCD screens, they use it to mask hardware related artifacts ( panel not fast enough, draws lines upside down, whereas DLP literally spits out whole frames-by color), lot of brightness is wasted this way.

Short a: yeah, with LCD screen its like that. And plasma is similar to LCD's pattern because the hold time is short. 60hz -> 16.7ms , 120hz -> 8.3 ms. So LCD comes at ~4mS at 120hz, which is the same number as a plasma display's 4mS hold time. So in the plasma screen viewpoint , its like theres no 1. variant, but only 2nd exists. With DLP you see with one eye all the time ( ~8mS , B,8mS ,B,8mS ....) , thats the first variant. In fact DLP is so fast, that it could do true 240hz ( ~4mS,B,4mS,B,4mS,B...) easily, it just doesnt seem necessary?? ...Maybe we'll try it with leds.

Long winded answer: in LCD 's they use something called active matrix, this sets the brightness of every pixel on the screen (it draws lines upside down). With active matrix , the pixel is held thru the entire frame time, and this is not how CRT's , or PDP's work. ~ plus, this method of displaying constant light is actually... wrong!
http://scien.stanford.edu/pages/labsite ... legers.htm

comparison between CRT with short hold time, and LCD with active matrix
http://www.avsforum.com/avs-vb/showthread.php?t=852878
So breaking constant light is good in one sense (reducing motion blur), but bad in another aspect, namely, since light is blocked, light is wasted. For time sequential 3d, you'd want a display where you can set the light intensity so that it entirely compensates for the glasses low light transmittance (it "peaks" with higher intensity during the open period, instead of constant but low intensity), and you wouldn't see ppl moaning about dark 3d experience on LCD's , displays like 2233rz are unbearably dark, and there isn't much comparison with DLP, apart that the "higher" resolution on the LCD won't make up for anything thats wrong, and takes its toll on GFX department.

[Dom]

Hi Neil and Tritosine umm is there any difference in DLP link glasses like what Tritosine is talking about in DLP projectors and tv's? I know they have a white flash coming from the projector to connect to the dlp link shutter glasses. And we were talking about Viewsonic and Iz3d possibly using dlp link on lcd monitors but anyhow does DLP link still go full HD3D lefteye,whiteflash,righteye,whiteflash,lefteye,whiteflash-continued?

I also wonder about all the different formats for stereo3d, checkerboard, time sequencial, interleave, dual input HMD.

I don't know to many facts about how stereo glasses work except that they gotta flash at the same rate as the refreshrate of the display. The more hertz in refreshrate in a monitor will yield more light to the eyes as the awesome 3d glasses blink faster keeping them open longer. I wonder if that is right or if the glasses are entirely fast they will not let any light in cause the dark field will be shown to much, I guess that process could be reversed to the glasses opening true and closing false sequence.

[lish]

Hi Guys!

We are getting set to produce a series of videos about the available 3D equipment on the market and how they work. However, I have a question about LCD shutter glasses and the modes they operate in. These are the modes I know about:

1. Left, Right, Left, Right
2. Left, BLACK (both left and right are black), Right, BLACK, Left, BLACK, etc.

Are the above patterns correct? Are there other patterns too?

Regards,
Neil

I am sorry to see this topic so later.

The LCD shutter mostly is work in L..R..L..R..L..R..L..R--------
Here I wrote .. between L and R because the shutter is a LCD screen, so it is not a completely bright when we move the voltage， it may take about 2ms to turn off the LCD(from black to bright), so most of the backlight of 3D TV insert a black image between L and R
So:
shutter:LLRRLLRRLLRRLL
TVs:LLRRLLRRLLRRLL
backlight:Y-Y-Y-Y-Y-Y-Y

here:LL means left images, RR means right images, Y means the backlight on, - means the backlight off.