I assume that's what Sharp Memory LCDs are doing to reach their absurdly low power specs.

I dunno if LCD screens are multiplexed, but embedded LCDs could need as many as 8x on/off cycles per pixel (because you save 87% fewer wires if you chain 8x pixels on the same line and then put them on different biases and have weird COMmon pins and rows and crap).

Sharp claims that a bit of storage is on each LCD/capacitor and this saves power somehow with smarter decision making. I assume it's minimizing the wasted power somehow (or even recycling the previous power shoved into the capacitor, which typically just goes to waste).

It's some proprietary formula in any case, so it's all guesswork. Only the Sharp Engineer/Inventor would know for sure.

From what I've tried to glean from patents and whitepapers, they have memory in the panel so that each sub-pixel can hold its state without being driven by the controller. The controller also can address sub-regions under the control of the application processor.

The net effect is that the app can vary refresh rate and also update a small part of the screen while leaving the rest static. In Garmin smartwatches, this is used to switch between 1 Hz, 1/60 Hz, and a hybrid mode where the overall screen is 1/60 Hz and small part is updated at 1 Hz. E.g. the seconds digits may remain active while the rest of the screen is static.

It also seems like they use more interesting sub-pixel arrangements. The limited color depth may involve different combinations of 1-bit sub-pixels rather than any cells driven into partially twisted states. I've seen diagrams claiming some white (unfiltered) and RGB filtered sub-pixels of different sizes.