Reason for Voyager LCD colors

[mdanoregon]

Hi,

I have several 12c calculators and noticed the LCD has different colors.

A couple prior to 1986 have a grey LCD.

Others made after 1986 have a yellowish LCD.

Two Platinum's have a grey LCD and a recent calculator made in China has a yellowish LCD so it seems the color choice is intentional.

Next to each other, the difference is noticeable.

Would anyone know the cause or reason for this?

Is it possible the grey to yellow LCD change around 1987 corresponded to chip changes?

In the image, the calculators are from 1982, 1986, and 1988 with the one from 1988 having the yellow display.