Casio's and Complex Numbers

[ijabbott]

(11-24-2018 01:05 AM)edryer Wrote:  The yellow I am remarking on was the LCD screen cover, which like the FX501/502P was "yellow" and was some sort of filter to protect early LCD compounds I believe... they were only around till about 1980.... they were also used on the early LCD watches (like the Seiko ones from 1976). I think only the first three Casio LCD Calculators (501P/502P/FX80) had this "filter".

I'm not sure why some LCDs had yellow filters, but I don't think they had any protective function. I suspect it was more for aesthetic reasons, or to improve contrast. There are plenty of LCD displays around from the time that didn't have the yellow filter (including some Seiko LCD watches from 1976) that are still perfectly readable.

Some displays suffer from "LCD rot" but that's usually due to the seal around the edges becoming compromised. (EDIT: Some do rot from the middle outwards though - perhaps due to micro fractures?)