curious

Everything is so heatedly Optimus is also discussing the Apple patent ... But I was curious: didn’t anyone still patent the analogue, where each key is not an OLED display, but an E-ink? Exclusively on the basis of the intended purpose (a not-so-often changing image, not too high power consumption), I personally thought such buttons where the surface is a display on "electronic ink" to be the ideal option ... I wonder what their relative cost is ...