Varitronix LCD 3 character display

Support
1

I would like to request some technical support or advice on one of the 3 digit displays that we are using in one of our industrial products. The part number is VI-321-DP-RC-S.

While testing at room temperature, one of our engineers noticed the liquid crystal was turning black from the top and bottom of the screen – in an area that was not one of the segments. As we watched, the black crept a little more into the screen, then some time later receded again. This process happened over about half an hour. The display continued to function normally during the effect – the displayed segments were changing while the effect was present.

The problem hasn’t been observed again. This is a photo of the effect before it was at the worst point.

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I hope that someone can suggest an explanation for this behaviour so we can learn how to avoid it in future.

2

Hello Ian,

It’s possible that the liquid crystal material is leaking from possible pressure damage or a bad seal on the panel. Is this something that was noticed after assembly of the part?

3

Been a while since I designed a basic LCD display into a product.

IIRC, for me this phenomenon was most often caused the housing/bezel touching the display and/or stray static electric charges.

4

It was noticed months to a year after the manufacture date and so far is a one-off occurrence. We haven’t had a problem with flexing of the screen, it is mounted with a backing stiffenening plate, and the buttons that get pushed underneath it are very soft touch and well spaced.

5

If the display is not under any sort of pressure from the housing it’s possible that it was a bad unit with a bad seal instead, but I am unable to confirm if this is the case.