Re: TI-H: backlight

[Prev][Next][Index][Thread]

Re: TI-H: backlight


>First off, this may sound dumb but I'm a beginner. I would like to make 
a
>lighting device for my TI-85. I plan on taking off the plastic covering 
over
>the screen and placing some LEDs in underneath and the put the covering 
back
>on. I then plan to have it get it's power through the link port. If 
anybody
>knows if this would not be good for my calc(too much battery drain 
etc.)
>Any suggestions please let me know.

Well, the problem is the way LCD screeens work. Look at your LCD and 
then look at it from an angle. the light reflects funny and you can 
hardly see your screen's pixels sometimes! If you put LEDs on the side 
or just ontop of the LCD, the light refects poorly and it won't light 
the screen. The only way to do it is to have the light come head on to 
the screen. The problem of glare and reflection then becomes the problem 
and you also have to have the LEDs far enough above the screen to light 
it all.

I have a good suggestion, but it takes time and patience. The solution 
is to light it from the back, hence the term "backlight." The way to do 
it is difficult, but it works very nicely. I have dome my 85 and 82 and 
have done an 85 by mail order service ($30 will get you a backlight 
(turbo done free on any calc that supports a turbo/slow switch). I 
guarantee my orders (If I break it, I buy it), plus I ship via US mail, 
and insure for more than the actual value, so if they drop it and it 
breaks, they have to fork over the cash!). My mail order upgrade service 
includes other upgrades as well. I'll also be building EuPs and 
EII/EIIIs when the parts are avaliable/when they are released.

Sorry about the long "ad," but the backlight is NOT a good project for a 
beginner (you said "First off, this may sound dumb but I'm a beginner"). 
I use a sheet of sanded plexiglass (the ultra thin kind), 4-6 yellow 
Superbright LEDs (Rat Shaq Red LEDs, or any red LED light gets absorbed 
and reflected stange on an LCD because of it's greenish tint. It makes 
your eyes sore and is hard to read. Yellow is very bright and looks 
nice), a small resistor (value depends on # of LEDs), and a switch. The 
upgrade requires that you remove all the foam from the back cover and 
the foam that holds the screen onto the smaller circuit board. You WILL 
crack the screen if you try to peel it. You MUST cut it with an 
extremely sharp knife. You can't slice through it either. you MUST do it 
slowly and CAREFULY. You CANNOT cut those plastic ribbons that connect 
the screen to the board. I usualy connect two LEDs in parrelel and then 
the pairs get connected in serial. This makes them share 
voltage+current. You are less likely to harm them from too much power 
(which isn't that likey in the first place). The whole group of LEDs 
shines into the edge of the sanded plexiglass. The light reflects onto 
the LCD when it hits the sanded surface. The screen looks fine with the 
Light both on or off. It lights the WHOLE screen nicely, infact, the 
only better system is an EL panel, like on an indiglo watch, and those 
are expensive and use an inverter that probably wouldn't fit ito the 
calc.

I have a spare TI-85 screen so I have a replacement for any TI-85's if I 
ever mess up a screen (I also would like to offer to purchase any dead 
calculators with GOOD screens from anyone who may have them).

I have figured out how the USPS mail insurance system works, so if any 
damages occur durring shipping, or even if there was a problem before 
shipping that didn't show up, and it does, then they have to cover the 
bill for whatever it was insured for. I like to insure things double for 
stuff I send. So you're safe sending it to me. I have done several calc 
upgrades, so I am definitly expirienced.

Contact me at "richfiles1@hotmail.com" if you have questions

Richard Piotter

E-Mail:
richfiles1@hotmail.com
richfiles@usa.net

The Richfiles:
http://www.geocities.com/SiliconValley/Lakes/5081/Richfiles.html
The Richfiles TI Page
http://www.geocities.com/Area51/Lair/8510/Richfiles.html
The Richfiles Model Building Page


______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com