Optically clear LCD to use with Arduino?

Hi. I’m trying to find an optically clear (non-diffusing) display with which I can darken individual pixels – basically, a pixel-addressable Liquid Crystal Light Valve (LCLV) or an LCD that doesn’t have a backing. This would be used for modulating brightness of an image projected through the display, which is why it is important that the material not act as a diffuser. I want something under $100 that is easily interfaced to an Arduino (actually, probably an ESP32) and is roughly square, with a display area of at least about 25x25mm, and no more than about 100x100mm. Pixel resolution isn’t critical, but on the order of 128x128 would be nice. Pixels don’t need lots of tonal control; in fact, monochrome clear/black would suffice, although color would be ok too.

I had tried to separate a backlight from a TFT LCD, but that didn’t go well. Perhaps taking the shiny backing off a transflective LCD would be better? I’d really prefer not to have to do surgery on the display. Any suggestions?

PS: In case you’re wondering, I’m an ECE professor at the University of Kentucky and this is for a little side project involving computational photography research. There is a chance that in addition to open source release of the design, this might lead to a product… which is why peeling backings off LCDs doesn’t seem like a great solution. :wink:

Hi Prof Hank, welcome to the Tech Forum!

Sounds like an interesting application. Based on your description, it would seem that you’ll need an active switching technology like TFT, as the passive LCD types are probably not capable of switching at a frequency sufficient to modulate for apparent brightness (presumably at least 25Hz for human perception).

That said, I am unaware of any off-the-shelf solution for you. The best recommendation I have would be to contact companies who make TFT products and see if they could possibly make a prototype for you. Vendors you might try would include:

Newhaven Display - https://www.digikey.com/en/supplier-centers/newhaven-display
Custom products request form: http://www.digikeycustomrequest.newhavendisplay.com

Kyocera Display - https://www.digikey.com/en/supplier-centers/kyocera-display
Value-added products: http://www.kyocera-display.com/solutions/value_add.asp

Thanks. I’ve already started that process. Definitely seems to be off the beaten path… although there are plenty of large-scale transparent LCD displays now and, of course, tiny ones used for projectors, there don’t seem to be many in the size range I’m looking for.

As for the brightness modulation, I’m also thinking about displays that have more than 1 bit depth per pixel or perhaps even getting a custom display and using analog levels to modulate brightness on segments (which would dramatically limit the number of segments I could handle).