screen brightness improvment idea?

**hotrod_nut** · 06-28-2006, 08:37 PM

Hey LCD experts out there ... I am a EE and I currently own and use a Lilliput 7" LCD for my CarPC. For those of us looking for a quick way to increase brightness will one of the following ideas work.

1) there are several sheets/films between the LCD and the back light. Is there a special combination that if I remove a few of these existing sheets that I could increase the brightness and the transflective abilities of the monitor?

2) in the light compartment I noticed the inside backing is white, I know this is for even light distribution but can I add a reflective backing here to obtain better transflective abilities?

Am I crazy

What do you think, remember I don't care about exact color, even color distribution, etc ... all I want to do is be able to read the screen during the day.

Cheers,
Pat

**spmclaugh** · 06-28-2006, 11:19 PM

Originally Posted by hotrod_nut

Hey LCD experts out there ... I am a EE and I currently own and use a Lilliput 7" LCD for my CarPC. For those of us looking for a quick way to increase brightness will one of the following ideas work.

1) there are several sheets/films between the LCD and the back light. Is there a special combination that if I remove a few of these existing sheets that I could increase the brightness and the transflective abilities of the monitor?

2) in the light compartment I noticed the inside backing is white, I know this is for even light distribution but can I add a reflective backing here to obtain better transflective abilities?

Am I crazy

What do you think, remember I don't care about exact color, even color distribution, etc ... all I want to do is be able to read the screen during the day.

Cheers,
Pat

You might be able to sacrifice light diffusion for raw brightness (though not even across the screen). If you're using the stock backlight, it probably has a pretty efficient lightguide, so you're not going to gain much. If you're upgrading your backlight, you definitely can gain a lot of raw brightness by completely eliminating diffusion, but expect a poor picture.

None of this has anything to do with making the LCD transflective, I think you need to do a little more research on that. People have been remarking on the new transflective LCD's having very little glare, which is true (due to the new touchscreens), and I'm guessing you're using the word to mean that. Transflective technology is basically a hybrid of front-lit (reflective) and back-lit (transmissive). You would have to *add* a layer which basically reflects a portion of the light (about half) and transmits the rest.

BTW, the white backing *is* reflecting the light.

**hotrod_nut** · 06-29-2006, 01:09 PM

spmlaugh, thanks for the reply on the diffusion films.

The "transflective" portion came into play with the 2nd part of the question. The idea is that having a mirror that "reflects" more light behind the LCD where the white background is now. Everyone knows that if want to suntan under your chin while laying at the beach you hold a mirror like surface to your face ... not a "white" sheet of plastic.

Point is that using a reflective tap on the back side of the LCD would reflect the natural light more efficiently. Natural meaning the sunlight shinning directly on the LCD. That is if it makes it buy the diffusion films.

Cheers

**turbocad6** · 06-29-2006, 01:18 PM

most transflectives use a semi opaque mirror film in front of the backlight diffuser...they are still heavily dependant on the backlight, & won't show a good image without it, where a fully reflective lcd will be perfectly viewable in direct sun with the backlight even turned off... but can't be rear illuminated any more for some reason... fujitsu makes a tablet that has a fully reflective 10.4" screen... it uses front illumination though...

It would be interesting to see what would happen if a real mirror was put behind the whole stack... I have a gutted & exposed lcd that I've been meaning to try this very thing... haven't gotten around to testing it yet though...

**hotrod_nut** · 06-29-2006, 01:43 PM

The approach I am going for is a front lit reflective LCD, just like you mentioned. I use to develop outdoor computer equipment for the military and we used that Fujitsu tablet your talking about. It was PERFECT!

Everyone has seen these types of displays, the original PDA use to ALL have these screens. The HP models I think still do. I think they are more expensive but are perfect for indoor and outdoor. For example Dell Axim PDAs don't use this technology and are more difficult to see out side.

I wonder if I would get close to OR show some type of improvement if I added a mirror like surface behind the LCD. They make a reflective tape used for automotive trimming, I was thinking this would be easy to place on the back. You can find it at most automotive stores.

**michael_16j** · 06-29-2006, 02:30 PM

why not use a two way mirror

**turbocad6** · 06-29-2006, 02:33 PM

that's kinda what is used in regular transflective... it's opaque, means it doesn't completely block light from the rear, like a 2 way mirror really... kinda like mirrored window tint..., which would probably work good for something like this I would think...

**michael_16j** · 06-29-2006, 02:35 PM

Transflective LCDs
Transflective construction starts with a transmissive LCD and adds a partially reflective mirror layer between the LCD and the backlight. Depending on the LCD manufacturer, the mirror layer can be either a half-silvered mirror or a full mirror with tiny holes punched in it. When a transflective LCD is used indoors, it is illuminated by the backlight just like a transmissive LCD, except that the mirror layer blocks some of the light. When a transflective LCD is used outdoors, ambient light reflects off the mirror layer and illuminates the LCD. Note that outdoors, light has to go through the LCD twice, once on the way in and once on the way out. This tends to makes the outdoor performance of a transflective LCD not as good as the indoor performance, where the light only has to go through the LCD once

how hard would it be to make one our selfs

**turbocad6** · 06-29-2006, 02:37 PM

a sheet of mirrored tint might do it?

**michael_16j** · 06-29-2006, 02:39 PM

I bet we could build it( Build it and they will follow) lol
But ya it doesnt seem so hard, we could also change to

ClearTek II Capacitive Touch Screens

Capacitive touch screen solutions are the clear choice wherever performance demands are high. From kiosks to gaming applications, they're environmentally robust and durable, yet highly sensitive with superb optical clarity.

No glare, from these, no need to match optics