Methods and apparatus for visual display

Patent metadata

Field	Value
Publication number	US-9343020-B2
Application number	US-201414451666-A
Country	US
Kind code	B2
Filing date	Aug 5, 2014
Priority date	Aug 5, 2013
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

In exemplary implementations of this invention, light from a backlight is transmitted through two stacked LCDs and then through a diffuser. The front side of the diffuser displays a time-varying sequence of 2D images. Processors execute an optimization algorithm to compute optimal pixel states in the first and second LCDs, respectively, such that for each respective image in the sequence, the optimal pixel states minimize, subject to one or more constraints, a difference between a target image and the respective image. The processors output signals to control actual pixel states in the LCDs, based on the computed optimal pixel states. The 2D images displayed by the diffuser have a higher spatial resolution than the native spatial resolution of the LCDs. Alternatively, the diffuser may be switched off, and the device may display either (a) 2D images with a higher dynamic range than the LCDs, or (b) an automultiscopic display.

First claim

What is claimed is:

1. A method comprising, in combination:
(a) transmitting light through a first spatial light modulator, then through a second spatial light modulator, and then through a diffuser layer, such that a front side of the diffuser layer displays a time-varying sequence of images that is observable, by temporal integration, as an observable image;
(b) using one or more processors
(i) to execute an optimization algorithm to compute optimal pixel states of pixels in the first and second spatial light modulators, respectively, such that the optimal pixel states minimize, subject to one or more constraints, a difference between a target image and the observable image, and
(ii) to output signals, which signals encode instructions to control actual pixel states of the pixels, based on the optimal pixel states computed in step (b)(i); and

(c) in accordance with the instructions, varying the actual pixel states of the pixels;

wherein
(A) the first spatial light modulator has a first spatial resolution, the second spatial light modulator has a second spatial resolution, and the observable image has a third spatial resolution,
(B) the third spatial resolution is greater than the first spatial resolution and is greater than the second spatial resolution,
(C) the observable image is displayed on the diffuser layer and comprises a projection, over an angular domain, of a light field incident on the diffuser layer, and
(D) the optimization algorithm includes calculations involving a splitting variable, which splitting variable is a matrix that encodes an intermediate light field produced by the first and second spatial light modulators.

2. The method of claim 1 , wherein the spatial light modulators are liquid crystal displays.

3. The method of claim 1 , wherein:
(a) the sequence of images is displayed under conditions, including lighting conditions, that have a flicker fusion rate for a human being; and
(b) the sequence of images is displayed at a frame rate that equals or exceeds four times the flicker fusion rate.

4. The method of claim 3 , wherein the frame rate is greater than or equal to 200 Hz and less than or equal to 280 Hz.

5. The method of claim 1 , wherein the optimization algorithm is split by the splitting variable into subproblems, which splitting variable is a matrix that encodes an intermediate light field produced by the first and second spatial light modulators.

6. The method of claim 1 , wherein the optimization algorithm includes an alternating direction method of multipliers (ADMM) algorithm.

7. The method of claim 1 , wherein the optimization algorithm includes a Simultaneous Algebraic Reconstruction Technique (SART) algorithm.

8. The method of claim 1 , wherein the optimization algorithm includes steps for non-negative matrix factorization in accordance with multiplicative update rules.

9. Apparatus comprising, in combination:
(a) a diffuser layer;
(b) a rear spatial light modulator (SLM);
(c) a front SLM positioned between the rear SLM and the diffuser layer; and
(d) one or more computers programmed to perform computations and output signals to control the front and rear SLMs such that:
(i) a front side of the diffuser layer displays a time-varying sequence of images that is observable, by temporal integration, as an observable image,
(ii) the computations include executing an optimization algorithm to compute optimal pixel states of pixels in the front and rear SLMs, respectively, such that the optimal pixel states minimize, subject to one or more constraints, a difference between a target image and the observable image,
(iii) the spatial resolution of the observable image is greater than the spatial resolution of the front SLM and is greater than the spatial resolution of the rear SLM,

(iv) the observable image is displayed on the diffuser layer and comprises a projection, over an angular domain, of a light field incident on the diffuser layer, and
(v) the optimization algorithm includes calculations involving a splitting variable, which splitting variable is a matrix that encodes an intermediate light field produced by the rear and front spatial light modulators.

10. The apparatus of claim 9 , wherein the SLMs are liquid crystal displays.

11. The apparatus of claim 9 , wherein the one or more computers are programmed to cause the sequence of images to be displayed at a frame rate that exceeds 100 Hz.

12. Apparatus comprising, in combination:
(a) a diffuser layer;
(b) a switch for activating or deactivating the diffuser layer, such that the diffuser layer is transparent when deactivated;
(c) a light field projector for projecting a light field onto a rear side of the diffuser layer, such that light exiting the front side of the diffuser layer displays a time-varying sequence of images that is observable, by temporal integration, as an observable image, which light field projector includes a first SLM and a second SLM; and
(d) one or more computers programmed
(i) to execute an optimization algorithm to compute optimal pixel states of pixels in the first SLM and second SLM, respectively, such that the optimal pixel states minimize, subject to one or more constraints, a difference between a target image and the observable image, and
(ii) to output signals to control the first and second SLMs

wherein
(A) the observable image is a projection, over an angular domain, of a light field incident on the diffuser layer,
(B) the optimization algorithm includes calculations involving a splitting variable, which splitting variable is a matrix that encodes an intermediate light field produced by the first and second SLMs, and
(C) when the diffuser layer is not transparent, the spatial resolution of the observable image is greater than the spatial resolution of the first SLM and is greater than the spatial resolution of the second SLM.

13. The apparatus of claim 12 , wherein the one or more spatial light modulators comprise liquid crystal displays.

14. The apparatus of claim 12 , wherein the light field projector includes a spatial light modulator and a microlens array.

15. The apparatus of claim 12 , wherein, when the diffuser layer is transparent:
(a) the spatial light modulators have one or more dynamic ranges, including a maximum SLM dynamic range, which maximum SLM dynamic range is the highest of these one or more dynamic ranges;
(b) the observable image has a dynamic range; and
(c) the dynamic range of the observable image is higher than the maximum SLM dynamic range.

16. The apparatus of claim 12 , wherein, when the diffuser layer is transparent, the observable image comprises an automultiscopic display.

17. The apparatus of claim 12 , wherein the switch is electronic.

Assignees

• Heide Felix
• Wetzstein Gordon
• Gregson James
• Raskar Ramesh
• Heidrich Wolfgang
• Massachusetts Inst Technology

Inventors

• Heide Felix
• Wetzstein Gordon
• Gregson James
• Raskar Ramesh
• Heidrich Wolfgang

Classifications

• G09G2340/0457

  Improvement of perceived resolution by subpixel rendering · CPC title

• G09G2300/023

  Display panel composed of stacked panels · CPC title

• G09G3/36 Primary

  using liquid crystals · CPC title