Re: TI-H: Backlit screen WORKS

To: ti-hardware@lists.ticalc.org
Subject: Re: TI-H: Backlit screen WORKS
From: Travis Brady <travis@pobox.alaska.net>
Date: Thu, 18 Dec 1997 21:54:54 -0900
References: <19971219055228.18780.qmail@hotmail.com>
Reply-To: ti-hardware@lists.ticalc.org

I made a light that i taped to my calculator and said it was backlit,
hahahahha



Richard Piotter wrote:
> 
> >When I was looking at the keyboard on my 86, I noticed a foam outline
> around
> >the screen that was about 1/8 inch thick.  I was thinking, maybe if I
> could
> >get many 1/16 inch LEDs to go around the foam, maybe a backlit screen
> would
> >be possible.  Just an idea, tho.
> 
> That is similar to what I did, but if you just shine the light on it, it
> won't cover the whole screen. Even if you do end up getting enough to
> light the screen, you'll drain your batterys fast and have a wierd
> effect with your pixels. There will be shadows and hard to view pixels
> that make it not worth the bother. You also have the GLARE from HELL!
> 
> I solved the glare by lighting the back of the screen and the problem
> with covering the whole screen with light was solved by using a thick
> diffuser.
> 
> It works great. 4-6, maybe less, LEDs will light your entire screen very
> brightly. It looks fine when the light is both on or off. It uses
> high-bright yellow LEDs that are easy to view (red is worst cause of bad
> shadowing and they make your eyes sore after a while. I couldn't find
> green ones that were very bright). The LEDs are about 20 mA each, but I
> combine them in a combination of both serial and paralel to spread out
> the 6v from the battery to all of them evenly.
> 
> The removal of the foam is difficult, but if you are patient and
> CAREFUL, you will beable to remove the foam that connects the screen to
> the circuit board. Once that's all removed, remove the foam from the
> back cover and the 1/8" foam on the front. Then peel the mirror off the
> back of the LCD. Put a plexiglass diffuder (front &/or back is sanded or
> scored to reflect light upwards to the screen from a source on the
> edge.) between the mirror and the LCD. Put in the LEDs allong the bottom
> of the screen and make sure you put insulating tape on the circuit
> board. then tape or glue the LEDs down. Connect the resistor and switch
> (variable resistor can be implimented as well). Screw the screen back on
> to the front cover, but not all the way. It won't completely screw down.
> No glue is used for any parts of the screen. The pressure will hold it.
> If your cover won't go on, see what is blocking it. DON'T FORCE IT.
> You'll break the screen or the display driver chip on the 82, 83, 85 CE,
> and 86. If you can almost close it, your best bet is to grind the LEDs
> flatter with a bench grinder. The knife sharpener on some electric can
> openers makes a nice hobby grinder as well, and you can probably find
> one easy. If you do grind the LEDs, dont' grind them so far that you
> damage the element and do NOT grind on the front. It neads to be clear
> and rounded to project the light well.
> 
> Direct any questions to richfiles1@hotmail.com
> 
> some of you may not want to mess inside your calcs, so I do offer the
> job for $35, including shipping & handling. I also turbo for free with
> any upgrade (if the calc can be turboed).
> 
> Thanks and I hope you try the backlight (good practice to try on a
> broken calc if you have one. You can easily take the LEDs and stuff out
> again. I also suggest that you use a very sharp knife on the foam and
> you take your time. I spend between 30 minutes to over an hour to remove
> the foam. It is easy to slip and cut the wires that connect the screen,
> and you CANNOT REPAIR THAT. That's why I lightly cut using repeated
> strokes. don't pull on the screen either or you'll crack it. You can try
> when you near halfway through the last piece of foam (2), but if the
> screen starts changing colors (like if you press it hard), then quit
> pulling. A little is ok, but use common sense. Don't pull if it won't
> come. cut more.
> 
> Good luck for all who try this!
> 
> Richard Piotter
> 
> E-Mail:
> richfiles1@hotmail.com
> richfiles@usa.net
> 
> The Richfiles:
> <A
> HREF="http://www.geocities.com/SiliconValley/Lakes/5081/Richfiles.html">The
> Richfiles TI Page</A>
> <A HREF="http://www.geocities.com/Area51/Lair/8510/Richfiles.html">The
> Richfiles Model Building Page</A>
> 
> ______________________________________________________
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References:
TI-H: Backlit screen WORKS
From: "Richard Piotter" <richfiles1@hotmail.com>