Adding a frontlight to LCD? (ie: ST Book)

[skeezix]

hey guys --

 

Frontlight technology was pretty common not that long ago (on PDAs for instance), and now is pretty much totally dead I think. The concept was often just adding some 'stage lights' at the top or bottom of the LCD panel, or using a frontlight panel that would just sit in front of the LCD panel (and behind any touchscreen.) I think, hardware is less my thing

 

It woudl be pretty awesome to add a frontlight to an old LCD system that has just a unlit LCD .. ie: The LCD is useful in high ambient light situations only. Adding frontlight coudl make it awesome.

 

Harder to get a frontlight that size perhaps, but more to point .. I know nothign about FL wire-ups, and it seems FL are hard to come by these days.

 

Anyone know _anything_ about this sort of tech? Would it be even possible to bolt-on a FL to an old system?

 

jeff

[nathanallan]

Tiny LEDs and a resistor could be used along the edge of a really thin piece of clear plastic, maybe 1/32, behind the digitizer.

 

They could all be powered with one coin cell 2032, or double it with a resistor.

 

Tape it all together (okay, embed it nicely inside with a battery case on back) and you have a frontlit screen. Not the greatest but in a bang up situation it would work.

 

Sounds liek a neat thing to do with an original un-lit GBA.

[skeezix]

This is actually for a laptop, without touchscreen; only mentioned PDAs for reference.

 

You think a LED could project light evenly across a surface? I should think it would be very .. bright one side, not at the other, and 'pooly' nearest the LED. But interesting idea.. maybe if the LED is along a thin piece of plastic/glass, it'd carry more evenly..

 

jeff

[nathanallan]

Oh yeah, the ultrabrights are great for stuff like this. You have to use many to spread evenly, but without a backlight it's really hard to get done perfectly. If, say, you used four on each side (or more, depends on the measurements) then it ought to cover the whole screen. There is math involved, which makes me want to make a model and spare the math.

 

but an LED has a 15 degree spread normally. The shape of the plastic housing it can widen that. Roughing up the surface makes it more ambient and less directional.

 

Maybe some neon with silver paint on one side will be more for this project. A lot thicker afaik, though.

 

The plastic will help carry it, like a light pipe, just make sure that it can enter the sides of the plastic and it is not rough (then it will diffuse it too much as if from a rough cut and reflect it back, too). So the sides have to be polished to clear.

 

More people have done more than I, hopefully they will chime in with their experiments.