High dynamic range displays using filterless LCD(s) for increasing contrast and resolution

• US 9,772,530 B2
• Filed: 05/15/2012
• Issued: 09/26/2017
• Est. Priority Date: 05/14/2010
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Gilbert, John
• Primary Examiner(s): Glick, Edward
• Assistant Examiner(s): CHUNG, DAVID Y
• Application Number:
  US13/472,076
• Publication Number:
  US 20120224121A1
• Time in Patent Office: 1,960 Days
• Field of Search: 349 61- 65, 349 74- 82, 362600-632, 345690
• CPC Class Codes: G02F 1/133601 for spatial active dimming
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/13471 in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells G02F1/13475 takes precedence
• CPC Class Codes: G09G 2300/023 Display panel composed of stacked panels
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: H04N 13/324 Colour aspects
• CPC Class Codes: H04N 13/337 using polarisation multiplexing
• CPC Class Codes: H04N 13/351 for displaying simultaneously

Abstract

A display provides increased contrast and resolution via first LCD panel energized to generate an image and a second LCD panel configured to increase contrast of the image. The second panel is an LCD panel without color filters and is configured to increase contrast by decreasing black levels of dark portions of images using polarization rotation and filtration. The second LCD panel may have higher resolution than the first LCD panel. A half wave plate and/or film is placed in between the first and the second panel. The panels may be directly illuminated or edge lit, and may be globally or locally dimmed lights that may also include individual control of color intensities for each image or frame displayed.

Claims

1. A display comprising:

a backlight;

an upstream diffuser, the upstream diffuser smoothing the light from the backlight;

an image-generating panel, the image-generating panel comprising a color LCD panel wherein the image-generating panel receives light from the backlight and produces a color image;

a contrast-improving panel, the contrast-improving panel comprising a monochrome LCD panel wherein the contrast-improving panel receives light from the image-generating panel and wherein further the contrast-improving panel comprises a lower resolution than the image-generating panel;

a half wave plate positioned between the image generating panel and the contrast improving panel; and

a polarizing preserving diffuser positioned between the image generating panel and the contrast improving panel, further wherein said polarizing preserving diffuser providing smooth variance of lighting within substantially a single pixel;

wherein the upstream diffuser is configured to mix light such that a single pixel of the upstream diffuser is substantially illuminated by a plurality of light sources in the backlight and the polarizing preserving diffuser is configured to mix light on a sub-pixel level to substantially mask high frequency details in the light from the image-generating panel onto the contrast-improving panel; and

a controller, the controller configured to;

receive input image data;

generate a polarization control signal from the input image data;

send the polarization control signal to the contrast-improving panel;

generate a color control signal for the image-generating panel, the color control signal generated from both the input image data and the polarization control signal; and

sending the color control signal to the image-generating panel.

2. The display according to claim 1, wherein the resolution of the contrast-improving panel is the same as the resolution of the image-generating panel.

3. The display according to claim 1, wherein the resolution of the contrast-improving panel is higher than the resolution of the image-generating panel.

4. The display according to claim 1, wherein the resolution of the contrast-improving panel is lower than the resolution of the image-generating panel.

5. The display according to claim 1, wherein the backlight comprises a direct lit backlight.

6. The display according to claim 1 wherein the backlight comprises an edge-lit backlight.

7. The display according to claim 1 wherein the backlight may comprise individually controllable light sources.

8. The display according to claim 7 wherein said light source may be controlled with respect to brightness.

9. The display according to claim 1 wherein said polarization-preserving diffuser is upstream of said half-wave plate.

10. The display according to claim 1 wherein said polarization-preserving diffuser is downstream of said half-wave plate.

11. The display according to claim 1 wherein said polarization-preserving diffuser is combined with said half-wave plate.

12. The display according to claim 1 wherein said image-generating panel is one of a group, said group comprising:

a color panel and a greyscale panel.

13. The display according to claim 1 wherein said contrast-improving panel is one of a group, said group comprising:

a color panel and a greyscale panel.

14. The display according to claim 1 wherein said polarization-preserving diffuser comprises a diffuser that substantially eliminates the visual moire between said image-generating panel and said contrast-improving panel.

15. The display according to claim 1 wherein said polarization-preserving diffuser comprises a diffuser that substantially minimizes the birefringence interaction with the polarization direction.

16. A display comprising:

a backlight;

an upstream diffuser, the upstream diffuser smoothing the light from the backlight;

a first stack structure, said first stack structure comprising;

a reflecting polarizer;

an initial polarizer;

a color LCD panel;

a finishing polarizer;

a half wave plate; and

a polarization-preserving polarizer, wherein said polarizing preserving diffuser providing smooth variance of lighting within substantially a single pixel; and

a second stack structure, said second stack structure further comprising;

an initial polarizer;

a monochrome LCD panel, the monochrome LCD panel comprising a lower resolution than the color LCD panel;

a finishing polarizer;

wherein the upstream diffuser is configured to mix light such that a single pixel of the upstream diffuser is substantially illuminated by a plurality of light sources in the backlight and the polarizing preserving diffuser is configured to mix light on a sub-pixel level to substantially mask high frequency details in the light from the first stack structure onto the second stack structure; and

a controller, the controller configured to;

receive input image data;

generate a polarization control signal from the input image data;

send the polarization control signal to the contrast-improving panel;

generate a color control signal for the image-generating panel, the color control signal generated from both the input image data and the polarization control signal; and

sending the color control signal to the image-generating panel.

17. The display according to claim 16 wherein said half wave plate affect a polarization of the image which is compatible with the initial polarizer of the second stack structure.