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Directional backlight

  • US 9,188,731 B2
  • Filed: 03/15/2013
  • Issued: 11/17/2015
  • Est. Priority Date: 05/18/2012
  • Status: Active Grant
First Claim
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1. A directional display device, comprising:

  • a transmissive spatial light modulator comprising an array of pixels arranged to modulate light passing therethrough; and

    at least two directional backlights, each comprising;

    a waveguide having an input end, first and second, opposed guide surfaces for guiding light along the waveguide, and a reflective end facing the input end for reflecting light from the input light back through the waveguide, the first guide surface being arranged to guide light by total internal reflection, the second guide surface comprising a plurality of light extraction features oriented to reflect light guided through the waveguide after reflection from the reflective end in directions allowing exit through the first guide surface as output light, the waveguide being arranged to direct input light originating from different input positions in a lateral direction across the input end into respective optical windows in output directions distributed in the lateral direction in dependence on the input positions, the directional backlights each being arranged to supply output light through the spatial light modulator;

    in respect of each directional backlight, an array of light sources at different input positions across the input end of the respective waveguide;

    a control system arranged to selectively operate the light sources to direct light into said optical windows corresponding to said output directions, the control system further comprising a sensor system arranged to detect the position of an observer relative to the display device, the control system being further arranged to control the display device to display temporally multiplexed left and right images and synchronously to direct the displayed images into viewing windows in positions corresponding to left and right eyes of an observer, in dependence on the detected position of the observer.

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