The big picture: Existing foldables with secondary screens typically utilize OLED or LCD panels. While these solutions afford superior resolution and responsiveness compared to E Ink displays, they aren't nearly as energy efficient as E Ink panels. Such displays are often used for non-mission-critical functions like telling the time or displaying notification alerts where a less capable but more energy efficient solution would be better suited for the job.
Apple is reportedly testing E Ink's electronic paper display (EPD) for potential inclusion in future foldable devices and / or tablets.
In a recent tweet, renowned Apple analyst Ming-Chi Kuo said E Ink's color EPD has the potential to become a mainstream solution for foldable devices' cover / secondary display.
Apple is testing E Ink's Electronic Paper Display (EPD) for future foldable device's cover screen & tablet-like applications. The color EPD has the potential to become a mainstream solution for foldable devices' must-have cover/second screen thanks to its excellent power-saving.— 郭明錤 (Ming-Chi Kuo) (@mingchikuo) May 17, 2022
Companies like Samsung and Oppo have led the foldable movement but power players including Apple are no doubt experimenting with similar technology behind closed doors. It remains to be seen if devices from other manufacturers will eventually see the light of day and will likely hinge on whether or not foldables become more mainstream in the coming years.
Last month, E Ink announced a new color display with an improved refresh rate called Gallery 3 that is fast enough to enable stylus input. It is unclear if Kuo is referring to Gallery 3 in his latest tweet but given the timing of the announcement, it wouldn't be surprising if they were one in the same.