Multi-half-tone imaging and dual modulation projection/dual modulation laser projection

Patent metadata

Field	Value
Publication number	US-10257477-B2
Application number	US-201414890133-A
Country	US
Kind code	B2
Filing date	Apr 14, 2014
Priority date	May 7, 2013
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

Smaller halftone tiles are implemented on a first modulator of a dual modulation projection system. This techniques uses multiple halftones per frame in the pre-modulator synchronized with a modified bit sequence in the primary modulator to effectively increase the number of levels provided by a given tile size in the halftone modulator. It addresses the issue of reduced contrast ratio at low light levels for small tile sizes and allows the use of smaller PSFs which reduce halo artifacts in the projected image and may be utilized in 3D projecting and viewing.

First claim

What is claimed and desired to be secured by Letters Patent of the United States is:

1. A method for preparing dual modulation energization signals for a dual modulation display comprising a light source illuminating a pre-modulator, a set of relay optics transmitting the light from the pre-modulator to a primary modulator, the method comprising:
determining a set of pre-modulator energization signals, the signals applied for more than one time period per single frame, whereby each pre-modulator energization signals induces the pre-modulator to create a plurality of half-tone images to be displayed or energized on a pre-modulator of a dual modulation display system over a plurality of sub-frames time periods during a single frame time period, such that the plurality of half-tone images that produces a desired Point Spread Function (PSF) that compensates for imperfections in the set of relay optics, wherein further the single frame period is a modulation period of the primary modulator and the sub-frame time period is a modulation period of the pre-modulator and the pixel elements of the primary modulator are switched on/off once during the single frame period and the pixel elements of the pre-modulator are switched on/off once during a single sub-frame period and further that the single frame period comprises a plurality of sub-frame time periods;
determining a set of primary modulator signals, the primary modulator signals energized in synchronization with the pre-modulator energization signals to produce an image to be displayed or energized on a primary modulator of the dual modulation display system.

2. The method according to claim 1 , wherein the half tone images are each displayed in a plurality of sub-frame time period each synchronized with the primary modulator signal.

3. The method according to claim 1 , wherein the pre-modulator signal is divided into a plurality of sub-frame images each sub-frame image energized in its own sub-frame time interval each sub-frame time interval synchronized with an interval of energization of the primary modulator and the primary modulator signal.

4. The method according to any of claim 1 wherein the method is implemented in a cinema projector having laser light sources illuminating the premodulator.

5. The method according to claim 4 , wherein the laser light sources are locally and globally modulated.

6. The method according to claim 4 , wherein the laser light sources are configured to emit at least 2 sets of light wavelengths each set comprising red, green, and blue wavelength lights wherein at least one of the same color wavelengths in different sets are separated by a minimum bandwidth necessary to accomplish off-axis viewing without cross-talk through passbands of viewing glasses at normal and off-axis viewing.

7. The method according to claim 6 , wherein the off-axis viewing is one of approximately 20 degrees.

8. A display device comprising a dual modulation architecture, comprising:
a pre-modulator configured to produce a low resolution image comprising pixels each pixel comprising a plurality of modulating elements of the first modulator, the pixels together forming the low resolution image;
a set of relay optics configured to transmit light from the pre-modulator, the relay optics comprising a given transfer function that include imperfections whereby the pre-modulator is energized by a set of pre-modulator energization signals that produce a plurality of half-tone images to be displayed or energized on a pre-modulator of a dual modulation display system over a plurality of sub-frames time periods during a single frame time period that compensate for the imperfections of the relay optics, wherein further the single frame period is a modulation period of the primary modulator and the sub-frame time period is a modulation period of the pre-modulator and the pixel elements of the primary modulator are switched on/off once during the single frame period and the pixel elements of the pre-modulator are switched on/off once during a single sub-frame period and further that the single frame period comprises a plurality of sub-frame time periods;
a primary modulator comprising a plurality of modulating element configured to further modulate the light transmitted from the set of relay optics with a set of primary modulator energization signals working in synchronization with the pre-modulator energization signals so as to produce a desired image for display.

9. The display device according to claim 8 , further comprising a controller configured to calculate a light field of the compensated low resolution image at the primary modulator and utilize the light field simulation to calculate drive values of the primary modulator.

10. The display device according to claim 8 , wherein the light field simulation and primary modulator drive values are calculated for each of separate light channels of the display.

11. The display according to claim 8 , wherein the display is a projector and the pre-modulator comprises a series of at least three modulating devices each modulating device assigned to a different color light channel.

12. The display according to claim 8 , wherein a black level of the image for display is better than 1/45000th off-white, when at least one of a desired number of pre-modulator pixels are turned on when placed in a grid fashion to create a PSF.

13. The display according to claim 11 , wherein the premodulator has at least 25 brightness levels and greater than 1800:1 contrast ratio.

14. The display according to claim 8 , wherein the display is a projector and the image to be displayed passes through a projection lens onto a screen for viewing by a viewer.

15. The display according to claim 14 , wherein dark level performance of the projector influenced mostly by a dark level of a room where the projector is utilized.

16. The display according to claim 9 , wherein the controller changes a ratio of premodulator pixels and/or contrast ratio depending on brightness levels in the image to be displayed.

17. The display according to claim 9 , wherein the controller is configured to shift a brightness range of a local area of the premodulator based on a brightness of a corresponding area the image to be displayed such that the primary modulator continues to use its full fidelity range throughout the corresponding area of the region.

18. The display according to claim 9 , wherein the controller is configured to set-up a plurality of half-tone settings on the premodulator for each image to be displayed.

19. The display according to claim 18 , wherein each halftone image comprises an n×n block of half tones each block comprising a pixel of the halftone image.

20. The display according to claim 19 , wherein the controller adjusts the half tone images so as to shift a brightness range of a local area of the premodulator based on a brightness of a corresponding area the image to be displayed such that the primary modulator continues to use its full fidelity range throughout the corresponding area of the region.

Assignees

• Dolby Laboratories Licensing Corp

Inventors

• Richards Martin J
• Shields Jerome

Classifications

• H04N9/3161

  using laser light sources (using laser beams scanning the display screen H04N9/3129) · CPC title

• G09G3/2033 Primary

  with splitting one or more sub-frames corresponding to the most significant bits into two or more sub-frames · CPC title

• H04N9/3126 Primary

  for spatial light modulators in series · CPC title

• G09G3/346

  based on modulation of the reflection angle, e.g. micromirrors (micromirrors devices per se G02B26/0833) · CPC title

• G09G3/002

  to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT · CPC title