[tomxor]

Was thinking something similar - rather than an old panel you could take a newer large high res panel, chosen carefully so it's easy to separate from the back-light.

I wonder what it would look like with just paper behind it instead? (or a slightly more reflective white material). I wouldn't expect color to "transflect" very well, but it might work ok as a simple 1-bit screen, fully transmissible as possible reflecting off the paper, or fully opaque.

The LCD still needs continuous power, but far far less than the backlight.

That might end up being a superior balance... a small amount of continuous power, with the benefit of up to 60hz refresh rate if you want it.

[gen3]

This sounds pretty similar to the display on the Pebble Time. It was a color LCD, sometimes marketed as a low power LCD or reflective LCD. For the majority of the time the display didn't use the backlight. They don't seem to be widely manufactured in my attempts to look for them... I should check again!

[numpad0]

Sharp’s Memory LCD, I think. Combination of SRAM cells to hold state in each pixel and improved reflexive backing, otherwise normal LCD, so data input can be stopped without losing contents.

Also to parent comment: backlit LCD without backlight looks like brownish tinted frosted glass. Transreflexives look like calculators and never like a paper. There were high contrast monochrome variant in those Memory LCD products and it looked like half silvered mirror, respectively.

[frosted-flakes]

Or the GameBoy Advance and Advance SP. The Advance SP had a toggle-able front light, but was very usable without it.

(A later version of the Advance SP had a regular back-lit LCD screen.)