FWIW
My best homebrew was taking a piece of acrylic or plexi (perspex?) 
lighting from both sides with leds after stuffing in behind the LCD.
(I think it was white paper behind that.)
Sanding the acrylic to diffuse (and force the light to leak at the 
scratches?) was key.
HTH
D

Jinx wrote:
> I'd like to LED backlight a 4-digit LCD and wonder if anyone
> has suggestions/comments or done anything similar
> 
> The first problem is that there's only 2mm between the top of the
> driver IC (40 pin DIP) and the bottom of the display. I've tried
> several types of LEDs and diffusing material (translucent acrylic,
> white plastic, patterned shower plastic) but the gap is so narrow
> hat the beam doesn't really have room to spread out. The best
> result was a blue or white LED off to end sides about 20mm away
> at a shallow angle. But I don't have room in the case to do that
> unfortunately. Pity, looks good. Any closer and the brightness of
> the LED highlights the "off" segments. Can't raise the LCD as
> there's a limit on both case depth and actuator length of the push-
> buttons I want to use
> 
> Ideally I'd like some diffuser that magically can spread the light out
> evenly from several point sources
> 
> Another option is to put the driver on the other side of the PCB. The
> connections between the IC and display are simplest as shown in the
> picture. To keep that simplicity, the pins of the IC would have to be
> bent up so that the top of the IC is against the bottom of the PCB. I
> worry about whether this would cause premature failure (if so, how
> premature ?) of it because of some kind of damage to the pin/body
> seal
> 
> 
> 
> ------------------------------------------------------------------------
> 

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist