Axiom Home Page Forums General Discussion Home Theater Backlighting for front projectors

Here's another one for the experts...

Not sure if this is the correct forum for this question...you may see me post it on other threads...

I have seen much discussion about the benefits of using a 6500kw lamp behind the screen of rear projection TVs to relieve the eye stress caused by watching TVs in the dark.

How would I accomplish this with a front projection TV given that the screen is virtually flush to the wall?

Thanks in advance!

You say "virtually" flush... I assume that means it sticks out a bit. You could try mounting some rope lights to the back of the screen's frame -- they would be out of sight, but light would spill out from behind the screen.

Maybe I'm just misreading it (or just not up on lamp technology), but 6500 kW ?!! That's 6.5 MW, which, if I remember right from the Roaming Blackouts a few years ago is near enough to power a city.

drmurray,

Perhaps you are talking about what's called "bias lighting" here. Bias lighting is a relatively dim, indirect illumination behind/around the imaging screen (whether it is RPTV or front projection). This provides some lit background, so that your eyes will be "fooled" to see blacker blacks on the projected image, resulting in a higher perceived image contrast. For front projection screens, the lamps are usually installed behind the screen along the edge, by having a just-enough space between the screen frame and front wall.

I have actually played around with some temporary bias-lighting setups when I installed my front projection screen. But I did not see any convincing benefits, so I decided to forget about them. Front-projected images are rarely "too bright" to be comfortable anyway, even with a high-gain screen. For me, viewing in complete darkness (except for reflections from the screen itself) is best.

I agree with sushi. On a front projection setup I would skip on bias lighting, but for RPTV's they do make a noticable difference. I'll try to find the link from where I got mine for anyone who wants to check'em out.Here ya go- www.cinemaquestinc.com/ideal_lume.htm

i have a 18"strip light on the back of my tv(just a regular projection tv) and it does relive the stress on my eyes when i use it.i never noticed what sushi mentioned about blacker blacks.ill have to check that out..ron

Yes in a home theater I would not want to be to close when he hit the switch, er, umm detonator...

Errrr...I meant 6500 Kelvin lamp used for bias lighting. Luckily you guys are smart enough to work with my handicap!

OK. That makes a lot more sense. I just couldn't figure out what the initials would stand for!

Hi all,

What eye stress? Do you expect to see bias lights or backlighting in a movie theater? Sushi's theory about blacker blacks sounds plausible, but in my gut the whole thing sounds like nonsense.

The best images, whether from a direct-view CRT, rear- or front-projection, are in a totally darkened room. Why do you think TV directors sit in dark control rooms looking at $10,000 Sony CRT monitors? (I used to work in TV in Toronto.) To know exactly what the camera image looks like, with the viewed image uncorrupted by ambient light.

Any addition of ambient light in a room with a TV image inevitably lessens its impact and the true reproduction of blacks.

Regards,