Patent ID: 9740034
Date: 2017-08-22
CPC Classifications: G02B,G02F,H04N

Claim:
1. A directional backlight apparatus comprising: a directional backlight comprising a waveguide comprising first and second, opposed guide surfaces for guiding input light along the waveguide, and an array of light sources arranged to generate the input light at different input positions in a lateral direction across the waveguide, the waveguide further comprising a reflective end for reflecting the input light back through the waveguide, the second guide surface being arranged to deflect light after reflection from the reflective end as output light through the first guide surface, and the waveguide being arranged to direct the output light into optical windows in output directions that are distributed in the lateral direction in dependence on the input position of the input light; and a sensor system arranged to detect a position of a head of an observer; and a control system arranged to selectively operate a group of adjacent light sources to direct light into a corresponding group of adjacent optical windows, in a manner in which the identity of the light sources in the group varies, and for a given group of light sources the luminous flux of the light sources varies, in accordance with the detected position of the head of the observer.