E Ink (the company) keeps improving their electrophoresis display technology. Unfortunately the technology necessarily has very low refresh rates since it it is based on moving around solid particles submerged in a liquid.
There were other passive e-paper display technologies like the one by Liquavista (based on moving colored oil droplets) or Mirasol by Qualcomm (mechanical micro-shutters create colored light via interference). These were capable of achieving high refresh rates, but unfortunately they have long been abandoned.
I believe the monochromatic electrophoresis displays by E Ink had higher reflectivity and lower price, which is what mattered for e-readers, so all the others went out of business.
There were other passive e-paper display technologies like the one by Liquavista (based on moving colored oil droplets) or Mirasol by Qualcomm (mechanical micro-shutters create colored light via interference). These were capable of achieving high refresh rates, but unfortunately they have long been abandoned.
I believe the monochromatic electrophoresis displays by E Ink had higher reflectivity and lower price, which is what mattered for e-readers, so all the others went out of business.