its been stated that using two lcd panels to improve contrast will not be efficient because of the wasted light. etc...
how about if two panels are used but one is normal color and the other is set to black & white. set the contrast and brightness all the way up on the B/W panel this way the panel is mostly transparent except for the dark parts of the image.
you will be holding back most of the light and thus will improve contrast with the dark scenes and colors...
just another thought...
ap0
how about if two panels are used but one is normal color and the other is set to black & white. set the contrast and brightness all the way up on the B/W panel this way the panel is mostly transparent except for the dark parts of the image.
you will be holding back most of the light and thus will improve contrast with the dark scenes and colors...
just another thought...
ap0
Thats been thought of before (lots of times actually..lol)
but no one has ever done it. I personaly think it WILL work....but im not sure about the B&W part though, since Retail prjs use 3 lcds some one should find out how the lcds are setup if they are all color or a hybrid of 2/1 B&W etc.
ND
but no one has ever done it. I personaly think it WILL work....but im not sure about the B&W part though, since Retail prjs use 3 lcds some one should find out how the lcds are setup if they are all color or a hybrid of 2/1 B&W etc.
ND
Commercial projectors use 3 monochrome lcd panels. I know this for a FACT because I have opened mine many times. Epson XGA 7500C & Epson SVGA 5500C.
I know this idea has been thought of before but the way it was explained was to use the two panels as they are. Full color. That would require massive amounts of lumens output from a lamp to get a good image onto the screen.
The way im explaining it is to set one lcd panel to "monochrome" to make only the dark part of the image darker (increase contrast) without affecting the regualr colors too much. You can still use your current lamp assembly with this type of set-up, I believe.
People were saying that running light through two panels would decrease your light (lumens output) to nothing. Which I believe is true but...I dont believe this will be the case with the method im explaining.
Filters will only give you a certain amount of color or contrast correctness. (is that a word?) anyways... You can pile on a few cc40 filters but imagine trying to correct the color? or contrast? or brightness?
My theory, two panels 400 contrast each.. would equal to 800 contrast on blacks.. while still maintaining 400 - 500 contrast for the bright part of the images , color etc...
Maybe im just not explaining it correctly.
ap0
I know this idea has been thought of before but the way it was explained was to use the two panels as they are. Full color. That would require massive amounts of lumens output from a lamp to get a good image onto the screen.
The way im explaining it is to set one lcd panel to "monochrome" to make only the dark part of the image darker (increase contrast) without affecting the regualr colors too much. You can still use your current lamp assembly with this type of set-up, I believe.
People were saying that running light through two panels would decrease your light (lumens output) to nothing. Which I believe is true but...I dont believe this will be the case with the method im explaining.
Filters will only give you a certain amount of color or contrast correctness. (is that a word?) anyways... You can pile on a few cc40 filters but imagine trying to correct the color? or contrast? or brightness?
My theory, two panels 400 contrast each.. would equal to 800 contrast on blacks.. while still maintaining 400 - 500 contrast for the bright part of the images , color etc...
Maybe im just not explaining it correctly.
ap0
It would work to a extent. But certainly also dim image from light loss at second panel. It would be more loss than you think. Unless you use the SAME light source divide it with 3 color filtering mirrors on a 45 angle. and then send to 3 panels monchrome like pro ones do. Then its all gains. But you also have to use a prism to remerge the image and be focused. Mirrors wont do and i looked up prisms for this-$500 is outta my range for experimenting. Black and white + color pic, wouldnt be the same at all as a monochrome setup.
Pre polarizing the light source would help contrast but at the cost of brightness. The entire build process is give and take.
And theres no way anyone is going to stack 2 LCD's on top of one another using the lamps and optics for this project and get a good image. You'd get better results building 2 units and projecting both of them onto the same screen. Yes you would be able to align the picture. But you would have to split fresnels and get just the right angle on the optics to get what your looking for.
And theres no way anyone is going to stack 2 LCD's on top of one another using the lamps and optics for this project and get a good image. You'd get better results building 2 units and projecting both of them onto the same screen. Yes you would be able to align the picture. But you would have to split fresnels and get just the right angle on the optics to get what your looking for.
you guys are leaveing out some very important issues..
you CANNOT stack two panels, they will be out of focus. they will have to be separate from eachother.
this makes convergence and almost impossible issue to deal with.
next, combining two lcds of 400 contrast wont make 800. it doesnt work like that.. if you gave one panel all red, and the other all blue, then you would get 400 contrast right? because all red would have a contrast of 400, blue 400, etc... therefore the image would have a total contrast of 400.
commercial projectors merely use multiple lcds to improve color rendering, contrast is maintained.
plus, the idea that you will lose a considerably amount of light is very valid. i just dont think from the DIY prespective you can do more than a single LCD.
you CANNOT stack two panels, they will be out of focus. they will have to be separate from eachother.
this makes convergence and almost impossible issue to deal with.
next, combining two lcds of 400 contrast wont make 800. it doesnt work like that.. if you gave one panel all red, and the other all blue, then you would get 400 contrast right? because all red would have a contrast of 400, blue 400, etc... therefore the image would have a total contrast of 400.
commercial projectors merely use multiple lcds to improve color rendering, contrast is maintained.
plus, the idea that you will lose a considerably amount of light is very valid. i just dont think from the DIY prespective you can do more than a single LCD.
everything i was saying is hypothetical. but for some reason it makes sense to me. i feel that it would probably work.
you have to keep something in mind. two panels 1 color 1 B/W. on the B/W panel raising the brightness all the way makes the lcd as tranparent as it possibly can be this b/w image will be really washed out (allowing the most light through) and raise the contrast all the way so that the whites become even whiter. (you can probably even do this with gamma settings) allowing most of the light through. this panel's job will only be to display a b/w image of the darkest parts of the scene. no color and very little detail.
the other normal panel (color) will be...well.... normal. it will work how it suppsed to.
i checked this with my 18" lcd monitor and when i set the brightness and contrast all the way up the image is extremely washed out and it displays only mostly the dark scenes only (set to b/w).
focusing.... yeah there could be a problem with focusing. but placing the panels glass to glass, back to back of each other will allow very little space between the actual pixel(s). the gap would be as thick as the the two glass layers of the lcd panels. i doubt there would really be a huge problem with the focusing, if any.
contrast.... you dont think you would get better contrast if you stacked two lcd panels? that is rediculous. you have twice the contrast because the first panel will block most of the light, so from 100%light you now have, lets say (hypotheticaly) umm..50% light. now this 50% light goes through the second panel and thus increasing contrast. I wouldnt doublt it if it even blocks all the light.
you know come to think of it maybe i mean black levels. contrast is the difference between dark and white.
the way i would set it up is by placing the color lcd ahead of the b/w like that the colors get less mudded up.
my 3 cents...
i have to go. continue my thoughts later...
ap0
you have to keep something in mind. two panels 1 color 1 B/W. on the B/W panel raising the brightness all the way makes the lcd as tranparent as it possibly can be this b/w image will be really washed out (allowing the most light through) and raise the contrast all the way so that the whites become even whiter. (you can probably even do this with gamma settings) allowing most of the light through. this panel's job will only be to display a b/w image of the darkest parts of the scene. no color and very little detail.
the other normal panel (color) will be...well.... normal. it will work how it suppsed to.
i checked this with my 18" lcd monitor and when i set the brightness and contrast all the way up the image is extremely washed out and it displays only mostly the dark scenes only (set to b/w).
focusing.... yeah there could be a problem with focusing. but placing the panels glass to glass, back to back of each other will allow very little space between the actual pixel(s). the gap would be as thick as the the two glass layers of the lcd panels. i doubt there would really be a huge problem with the focusing, if any.
contrast.... you dont think you would get better contrast if you stacked two lcd panels? that is rediculous. you have twice the contrast because the first panel will block most of the light, so from 100%light you now have, lets say (hypotheticaly) umm..50% light. now this 50% light goes through the second panel and thus increasing contrast. I wouldnt doublt it if it even blocks all the light.
you know come to think of it maybe i mean black levels. contrast is the difference between dark and white.
the way i would set it up is by placing the color lcd ahead of the b/w like that the colors get less mudded up.
my 3 cents...
i have to go. continue my thoughts later...
ap0
apo
apo if u guide the same light through 2 lcds separatley u will gain light, if u guide one beam of light through 2 lcds together u will loose light, if u wer to get the 2 lcds and have one colour and one monochrome have the same beam of light split into 2 so they both have the same amount of light going through each lcd separatley, have a mixing prisim after lcd's before projection lens u will gain alot of light and u will have darker darks maybe, but then also the whites will be brighter and very well look like an image with a very high intensity washing out the blacks anyway or the blacks will be blacker and the whites to darn bright.
Trev
apo if u guide the same light through 2 lcds separatley u will gain light, if u guide one beam of light through 2 lcds together u will loose light, if u wer to get the 2 lcds and have one colour and one monochrome have the same beam of light split into 2 so they both have the same amount of light going through each lcd separatley, have a mixing prisim after lcd's before projection lens u will gain alot of light and u will have darker darks maybe, but then also the whites will be brighter and very well look like an image with a very high intensity washing out the blacks anyway or the blacks will be blacker and the whites to darn bright.
Trev
you cant polish a turd.
if the panel has low contrast, adding another one wont help.
and keep in mind about the focusing issue... you said it will be glass to glass, with just a TINY bit in between. yes, BUT, keep in mind you are PROJECTING that image. if you project a 10" screen into a 100" screen, that 1mm gap becomes 10mm. thats a pretty big gap onscreen.
if the panel has low contrast, adding another one wont help.
and keep in mind about the focusing issue... you said it will be glass to glass, with just a TINY bit in between. yes, BUT, keep in mind you are PROJECTING that image. if you project a 10" screen into a 100" screen, that 1mm gap becomes 10mm. thats a pretty big gap onscreen.
yeah i mean glass to glass... no gap.. stuck together, no air in between.. get my drift? no space.... except for the thickness of the glass itself. lets say a lcd panel (glass only)is 3mm wide, the thickness of the two combined will be 6mm NOT 7mm or 8mm etc..
imagine if the beam of light was split into two so that each panel has its own light source, how big would that projector be? the size of a coffin? the whole idea is to "improve specs" without changing the size of the projector. and where the hell would you get a 10" - 15" prizm (imagine the cost). thats why i didnt bring any of that up becase THAT will be impossible...
im really going to look into trying this with those 5" panels. just to see what happens.
screw contrast im talking about better black levels. darker scenes etc...
once again, you'll have two sets of controls that can be used to control the "wash-out" and color balance and and and and...
no? im sure some people think that this will work. others just feel that it has to be done only one way cause that is the way they know and they've been doing it.
anyone have two lcd panels?
imagine if the beam of light was split into two so that each panel has its own light source, how big would that projector be? the size of a coffin? the whole idea is to "improve specs" without changing the size of the projector. and where the hell would you get a 10" - 15" prizm (imagine the cost). thats why i didnt bring any of that up becase THAT will be impossible...
im really going to look into trying this with those 5" panels. just to see what happens.
screw contrast im talking about better black levels. darker scenes etc...
once again, you'll have two sets of controls that can be used to control the "wash-out" and color balance and and and and...
no? im sure some people think that this will work. others just feel that it has to be done only one way cause that is the way they know and they've been doing it.
anyone have two lcd panels?
Just a point that should be noted before anybody goes out and spends any money...
An LCD works by rotating the lights polarisation by 90 degrees as it passes through the panel (see here for an example) - two identical panels will not work because the light exiting the first will be in completely the wrong polarisation plane to enter the second.
There are a couple of solutions, first rotate the second panel by 90 degrees (not ideal because of the loss of useable area plus the problems of rotating the image on the second screen). Second, place the second LCD backwards - but that would still involve flipping the image either horizontally or vertically on the second panel.
Add these problems to the fact that you will need to perfectly align the pixels (at approx 0.2mm each) in order to get maximum light output, this isn't going to be easy.
Please don't let me stop anybody trying this, I'm by no means saying that it can't be done, in fact I think that it can and that the results would probably be very good... But it will take a lot of patience and effort!
Steve
An LCD works by rotating the lights polarisation by 90 degrees as it passes through the panel (see here for an example) - two identical panels will not work because the light exiting the first will be in completely the wrong polarisation plane to enter the second.
There are a couple of solutions, first rotate the second panel by 90 degrees (not ideal because of the loss of useable area plus the problems of rotating the image on the second screen). Second, place the second LCD backwards - but that would still involve flipping the image either horizontally or vertically on the second panel.
Add these problems to the fact that you will need to perfectly align the pixels (at approx 0.2mm each) in order to get maximum light output, this isn't going to be easy.
Please don't let me stop anybody trying this, I'm by no means saying that it can't be done, in fact I think that it can and that the results would probably be very good... But it will take a lot of patience and effort!
Steve
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