| Author | Message | ||
     Miles Rating: N/A |
Hi, well I haven't had a lot of time recently to research my homebrew HMD project, but I started again tonight. I was reading about LCOS field sequential.. yes it's cheap, but I think I understand some fairly bad things from what I read. OK, so for 800x600 it would have 480,000 pixels, not 3x480k like a normal TFT, so that's good - the pixels can be square and right up against each other. So how it seems to work is (for 60Hz), in the first 1/180sec it displays the Red field with a red backlight LED (or similar), then in the next 1/180 it does Green, then Blue. OK, but you don't have all the Red information until the END of the frame. This means it stores the frame in a buffer and LAGS the display by ONE FRAME. This sucks!! For gamers, that's a disaster. What you see is 16ms behind! However, if we jump the video card up to 120Hz (to get 2 60Hz views out - i want stereoscopic here), assuming we can put a 60Hz frame into the display's frame buffer in 1/120 of a second, one view is now 8ms behind, and the other is 16ms behind. Not AS bad, but still terrible. Gamers - be aware of this when buying LCOS glasses!! OK, now I'm going to need some advice from real TFT experts out there. Firstly, who makes full color micro TFTs? Some data sheets would really help me! First thing I want to know is, do TFTs work like this - ie one color at a time with a frame buffer, or can they draw all three colors at the same time??? If they can, my plan is to have the video card spit out a 800x1200 frame every 1/60 of a second, and draw alternate lines on alternate displays (of course, the left and right views will be interlaced into the double height image.. I will assume I can do this). Now can anyone give me some advice on the above? Are there drivers which I can use to make the line interlaced double height image? I would really like to do this to keep both eyes updating as close to simultaneously as possible, with as little lag as possible. Will a TFT be able to draw a line that fast? It would be like a line from a 120Hz signal, but with long gaps between them. Please, also, where can I find data sheets on micro displays?! I really am not terribly interested in those LCOS color field sequential glasses if they are introducing 16ms LAG. In fact, I really wouldn't want to do it unless I can alternate displays on a per line basis - I don't want my displays updating 16ms apart - could play havoc with my brain!! | ||
| Miles Rating: N/A |
I have been thinking about it some more.. the LCOS does pose a slight advantage in one way.. as it is filling a frame buffer, it will probably have no problem with the strange timings I would apply (fast but not often lines).. then the lag can be reduced by increasing the frame rate. For example, I think the displays can do maximum 90Hz.. so if we get the video card sending 180Hz (GeForce 4 anyone?), hopefully the frame buffer will have no problems (it has to send it out at 270Hz after all), and the lag is reduced: 1 eye will be 5.556ms behind, the other 5.565ms behind. I guess a 5ms lag isn't *too* bad. I could accept 5ms given the far lower price. |
