Calculator displays

From: Philip.Belben_at_powertech.co.uk <(Philip.Belben_at_powertech.co.uk)>
Date: Tue May 12 07:05:30 1998

>> It was also not the display I have in my other digital voltmeter
>> (Dynamco, I think) which has as digits a multilayer Perspex sandwich.
>> Each perspex layer has a dot pattern for a character drilled in it; you
>> light up a character by illuminating the edge of the appropriate perspex
>> wafer, and total internal reflection confines the light to that wafer,
>> thus lighting up the dot pattern of only the one character. Neat.
>
> I've seem those used with a 2-colour (black, or illuminated red)
> background for +ve or -ve results. Problem is, I can never remember if
> red is +ve (as an engineer would use) or -ve (as an accountant would
> use)... Actually, didn't Dynamco do that on some of their voltmeters?

IIRC my Dynamco uses red for negative.

Philip.
Received on Tue May 12 1998 - 07:05:30 BST

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