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Removing light source from LCD

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#1 Michael Tien

Michael Tien


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Posted 21 April 2004 - 05:48 PM

Can one remove the cold cathode filament tube and replace it with a piece of translucent plastic? My thinking is that it is hard to see your average LCD in bright sunlight because the LCD backlight is so dark compared to the sun. A piece of translucent plastic would pick up the ambient light from behind which would be brighter that the existing light source. It would be like the lcd panels that you can put on an overhead projector. Any thoughts.?

Michael Tien
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#2 RobVanGelder


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Posted 21 April 2004 - 09:03 PM

Hi Michael,
I have been thinking about such a solution some years ago. I´m sure it will work in theory, however, the varying lightoutput that you will experience when your screen doesn´t see a bright source whill be very disturbing.
I mean, what happens when you walk in the shadow, or have to walk out of or in to a building?
The use will be very limited, in my opinion.

Basically, the lightsource is separated from the screen panel. There is still a larg board with the electronics, so it would mean that the whole screen-housing will get much bigger to get this electronic board out of the light path.

But I think you can design something where this board would be in a 45 degree angle to the screen, allowing for a mirror that will reflect the light coming from the front ( as seen from the camera) . I´m not sure if this would cover the whole screen, dark edges will be likely.

Open up a cheap LCD panel and check it out!

Rob van Gelder, Bangkok, Thailand
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#3 RobVanGelder


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Posted 21 April 2004 - 09:10 PM

Just to add some extra technical details:

The main problem with LCD creens is not so much the light output as well the glare on the screen.
That´s why the people from the Hummingbird have gone that way, adding a superior anti glare filter that enhances the contrast and therefore the visibility much more that only an increased light output can do. And it saves batteries too!

Another thing is that LCD has a certain maximum to its density, so when you put more light through it, it will become gray where it should be black, while the white is already at it´s max. The whole picture will be washed out, I think.

Rob van Gelder, Bangkok, Thailand
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