Image display
A display has a screen which incorporates a light modulator. The screen may be a front projection screen or a rear-projection screen. The screen is illuminated with light from a light source comprising an array of controllable light-emitters. The controllable-emitters and elements of the light modulator may be controlled to adjust the intensity of light emanating from corresponding areas on the screen. The display may provide a high dynamic range.
1. A display comprising:
a light source comprising an array of light-emitting elements each having a controllable light output;
a spatial light modulator illuminated by-the light source; and
a grid of reflective-walled channels disposed between the light source and the spatial light modulator;
wherein light from the light source passes through the channels to illuminate the spatial light modulator.
2. A display according to claim 1 wherein the array of light-emitting elements comprises a rectangular array.
3. A display according to claim 1 wherein the grid comprises a honeycomb structure.
4. A display according to claim 3 wherein the honeycomb structure comprises an aluminium honeycomb material.
5. A display according to claim 3 wherein the light-emitting elements are arranged in a hexagonal array.
6. A display according to claim 1 wherein reflective walls of the channels provide an interface at which light is totally internally reflected.
7. A display according to claim 1 wherein the grid is spaced away from the spatial light modulator.
8. A display according to claim 1 wherein the channels have a length L which satisfies
L
=
R
tan
(
θ
1
2
)
wherein R is the half-width of the channel and θ 1/2 is the angle at which light from one of the light-emitting elements has an intensity equal to one half of the intensity of illumination provided by the light-emitting element in a forward direction on-axis of the light-emitting element.
9. A display according to claim 1 wherein the light-emitting elements emit white light.
10. A display according to claim 1 wherein the light-emitting elements comprise light-emitting diodes.
11. A display according to claim 10 wherein the grid is provided by columns formed integrally with material that encapsulates the LEDs.
12. A display according to claim 1 wherein one of the channels is provided for each of the light-emitting elements.
13. A display according to claim 1 wherein, for each of the channels, the light source comprises a plurality of LEDs.
14. A display according to claim 13 wherein the LEDs for each of the channels emit light of a plurality of different colours.
15. A display according to claim 13 wherein LEDs operative to emit a mix of red, green, and blue light correspond to each of the channels.
16. A display according to claim 1 wherein the grid functions to improve uniformity of illumination of that part of the spatial light modulator illuminated by each of the light-emitting elements.
17. A display according to claim 1 wherein the channels are hexagonal in cross-section.
18. A display according to claim 1 wherein the channels are triangular or square in cross-section.
19. A display according to claim 1 comprising a controller connected to control the light-emitting elements of the light source to provide a low-resolution version of an image to be displayed on the spatial light modulator.
20. A display according to claim 1 wherein the spatial light modulator is a high-resolution colour light modulator.
21. A display according to claim 1 wherein the display has a thickness of 10 cm or less.
22. A display according to claim 1 wherein the reflective-walled channels comprise columns of light-transmitting material having walls at which light is internally reflected.
23. A display according to claim 22 wherein the columns are integral with the light-emitting elements.