Which side of LCD is better for projection?

voovoov · 27th March 2005, 06:03 PM

I asked this question in LCD forum, but no one has answered this question. I think people in this forum have more experience.
I built a MKIII projector with a second surface mirror behind the projection lens, but I found I got a brighter and clearer image when I projected without the mirror. You know the image is reversed without the mirror. In order to get a normal image, I reversed the LCD, the front of LCD panel facing the lamp, but I found the brightness was reduced. What I did is just to reverse the LCD, nothing else has been changed. If my observation is correct, the normal layout, the backing of LCD facing the lamp, gives better result. Can anybody confirm my observation? or I did something wrong?
I used Dell 151FP, the setup is BF, LCD, FF and projection lens.

Rox · 27th March 2005, 06:48 PM

yes, i have not tested it myself but know people at my favorite forum website at spain that have seen similar results. It looks like the lcd has been designed to work on a proper way and not on the other.

My friends told me that both luminosity and contrast falls down when light enters from the wrong side (not from where backlight would enter). the problen is the reversed image, but there are 3 solutions at least;

1) software mirror; a dvd reversed player or windows reverser or nkeystone for nvidia users.

2)first surface mirror between lcd and triplet or after triplet (only one).

3)retroprojection throw a semi trasparent sheet. (larger room needed)

dj_holmes · 27th March 2005, 10:12 PM

i wondered about this for ages. no i get such good results from a 150 hqi. people with ohp are better off after all!!!!!

Bigg'un · 27th March 2005, 11:33 PM

When I stripped my benq 567s v2 I noticed the same fenomenon, if you look or feel carefully, the side that light enters is smooth and glass like, the other side has a film like thin black plastic on it. When I tested my light source on it the wrong way (just to see what it would look like) it was very dimm and the colours were crap too....very grainy even when viewing a dvd. Anyway, in short, only work the way they were meant to AFAIK.

part2wanksta · 27th March 2005, 11:53 PM

where do you get a mirror program

Rox · 28th March 2005, 08:00 AM

there are divx players that can mirror the image (only the video, so windows remains like is). The nvidia video cards can download the nkeystone program that mirrores the full screen.

dj_holmes · 30th March 2005, 10:03 PM

on my 5.6" and on my 15" benq and your right about the smooth side.........well think about it sunglasses are also designed that way. let more light in on one side than the other!

sbisdabomb · 31st March 2005, 06:27 AM

I noticed the same thing on my pannels, the side the light is supposed to come through is smoother, less blury, and more glass like. However, I also noticed that it looks as though it's more reflective, I can see myself in the reflection when looking from the backlight side, I wonder if this side reflects more of the light as well.

27th March 2005, 06:03 PM	#1
voovoov diyAudio Member Join Date: Dec 2004 Location: st louis, MO	Which side of LCD is better for projection? I asked this question in LCD forum, but no one has answered this question. I think people in this forum have more experience. I built a MKIII projector with a second surface mirror behind the projection lens, but I found I got a brighter and clearer image when I projected without the mirror. You know the image is reversed without the mirror. In order to get a normal image, I reversed the LCD, the front of LCD panel facing the lamp, but I found the brightness was reduced. What I did is just to reverse the LCD, nothing else has been changed. If my observation is correct, the normal layout, the backing of LCD facing the lamp, gives better result. Can anybody confirm my observation? or I did something wrong? I used Dell 151FP, the setup is BF, LCD, FF and projection lens.

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27th March 2005, 06:48 PM	#2
Rox diyAudio Member Join Date: Jul 2004 Location: ?	yes, i have not tested it myself but know people at my favorite forum website at spain that have seen similar results. It looks like the lcd has been designed to work on a proper way and not on the other. My friends told me that both luminosity and contrast falls down when light enters from the wrong side (not from where backlight would enter). the problen is the reversed image, but there are 3 solutions at least; 1) software mirror; a dvd reversed player or windows reverser or nkeystone for nvidia users. 2)first surface mirror between lcd and triplet or after triplet (only one). 3)retroprojection throw a semi trasparent sheet. (larger room needed)

27th March 2005, 10:12 PM	#3
dj_holmes diyAudio Member Join Date: Nov 2004 Location: london	i wondered about this for ages. no i get such good results from a 150 hqi. people with ohp are better off after all!!!!!

27th March 2005, 11:33 PM	#4
Bigg'un diyAudio Member Join Date: Feb 2005 Location: NS	When I stripped my benq 567s v2 I noticed the same fenomenon, if you look or feel carefully, the side that light enters is smooth and glass like, the other side has a film like thin black plastic on it. When I tested my light source on it the wrong way (just to see what it would look like) it was very dimm and the colours were crap too....very grainy even when viewing a dvd. Anyway, in short, only work the way they were meant to AFAIK.

27th March 2005, 11:53 PM	#5
part2wanksta diyAudio Member Join Date: Aug 2003 Location: new mexico	where do you get a mirror program

28th March 2005, 08:00 AM	#6
Rox diyAudio Member Join Date: Jul 2004 Location: ?	there are divx players that can mirror the image (only the video, so windows remains like is). The nvidia video cards can download the nkeystone program that mirrores the full screen.

30th March 2005, 10:03 PM	#7
dj_holmes diyAudio Member Join Date: Nov 2004 Location: london	on my 5.6" and on my 15" benq and your right about the smooth side.........well think about it sunglasses are also designed that way. let more light in on one side than the other!

31st March 2005, 06:27 AM	#8
sbisdabomb diyAudio Member Join Date: Dec 2004 Location: fort collins, co	I noticed the same thing on my pannels, the side the light is supposed to come through is smoother, less blury, and more glass like. However, I also noticed that it looks as though it's more reflective, I can see myself in the reflection when looking from the backlight side, I wonder if this side reflects more of the light as well.

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