Light Shuttering for Waveguide Pupil Expansion

A light engine arranged to form an image visible from a viewing window, wherein the light engine comprises:

• a display device arranged to display a hologram of the image and spatially modulate light in accordance with the hologram;
• a waveguide pupil expander arranged to receive the spatially modulated light and provide a plurality of different light propagation paths for the spatially modulated light from the display device to the viewing window;
• and
• a light shuttering device disposed between the waveguide pupil expander and the viewing window, wherein the light shuttering device comprises (i) a plurality of liquid crystal cells, wherein each liquid crystal cell is operable in a first optical state or a second optical state in response to a respective first or second drive signal, and (ii) a drive circuit comprising (a) a plurality of switches, wherein each switch is arranged to output the respective first or second drive signal to a respective liquid crystal cell, and (b) a drive controller arranged to sequentially update the output of each switch during an update cycle;
• and
• wherein the drive circuit of the light shuttering device is arranged to determine an order in which the switches are sequentially updated during an update cycle based on any changes to the respective drive signals that will be made during the update.