Techniques for dual modulation display with light conversion

• US 9,940,881 B2
• Filed: 02/13/2014
• Issued: 04/10/2018
• Est. Priority Date: 03/08/2013
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Ninan, Ajit, Wan, Chun Chi
• Primary Examiner(s): MISTRY, RAM A
• Application Number:
  US14/370,115
• Publication Number:
  US 20150287368A1
• Time in Patent Office: 1,517 Days
• CPC Class Codes: G02F 1/133601 for spatial active dimming
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: G02F 2202/36 Micro- or nanomaterials
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules

Abstract

Techniques for driving a dual modulation display include generating backlight drive signals to drive individually-controllable illumination sources. The illumination sources emit first light onto a light conversion layer. The light conversion layer converts the first light into second light. The light conversion layer can include quantum dots or phosphor materials. Modulation drive signals are generated to determine transmission of the second light through individual subpixels of the display. These modulation drive signals can be adjusted based on one or more light field simulations. The light field simulations can include: (i) a color shift for a pixel based on a point spread function of the illumination sources; (ii) binning difference of individual illumination sources; (iii) temperature dependence of display components on performance; or (iv) combinations thereof.

Claims

1. A method for driving a local-dimming display comprising:

generating, based on image data, backlight drive signals to drive individually controllable blue illumination sources of a backlight,

emitting a first light by a plurality of the individually controllable blue illumination sources onto a same light conversion layer, the light conversion layer formed as a plane;

converting the first light into second light by the light conversion layer, the light conversion layer includes at least quantum dots;

generating, based on image data, modulation drive signals to determine transmission of the second light through individual subpixels of the display;

determining a color shift by the light conversion layer to the second light for a first pixel of the display based upon one or more of the backlight drive signals and a distance between the first pixel and at least one of the individually controllable blue illumination sources;

adjusting a first modulation drive signal for at least one subpixel of the first pixel based on the determining of the color shift of the first pixel;

determining a color shift by the light conversion layer to the second light for a second pixel of the display based upon one or more of the backlight drive signals and a distance between the second pixel and at least one of the individually controllable blue illumination sources; and

adjusting a second modulation drive signal for at least one subpixel of the second pixel based on the determining of the color shift of the second pixel, wherein the adjusting of the first and the second modulation drive signals occurs concurrently.

2. The method of claim 1 wherein the individually controllable blue illumination sources of the backlight includes light emitting diodes.

3. The method of claim 2 wherein the light emitting diodes are blue light LEDs.

4. The method of claim 1 wherein the modulation drive signals control an LCD.

5. The method of claim 1 wherein the determining of the color shift models the individually controllable blue illumination sources of the backlight as having a first point spread function (PSF) for broadband light spectral components and a second PSF for yellow light spectral components, the first PSF being narrower than the second PSF.

6. The method of claim 1 wherein the determining of the color shift models the individually controllable blue illumination sources of the backlight as 9 convolution channels.

7. A computer readable, non-transitory storage medium, storing software instructions, which when executed by one or more processors cause performance of the method recited in claim 1.

8. An apparatus comprising a processor and configured to perform the method recited in claim 1.

9. The method of claim 1, further comprising:

determining one or more derating functions for temperature dependence of the individually controllable blue illumination sources or the light conversion layer to address optical sheet warping; and

adjusting modulation drive signals based on the one or more derating functions.

10. The method of claim 9, wherein the one or more derating functions for temperature dependence is determined as additional convolution channels.

11. A method for driving a local-dimming display comprising:

generating, based on image data, backlight drive signals to drive individually controllable, blue LED sources of a backlight,

emitting first light by a plurality of the individually controllable, blue LED sources onto a same quantum dot layer, the quantum dot layer formed as a plane;

converting the first light into second light by the quantum dot layer;

generating LCD modulation drive signals to determine transmission of the second light through individual subpixels of the display by an LCD array;

determining an increase in yellow light spectral components from the quantum dot layer on the second light for a first pixel of the display based upon one or more of the backlight drive signals and a distance between the first pixel and at least one of the blue LED sources;

adjusting a first LCD modulation drive signal for at least one subpixel of the first pixel based on the determining to reduce yellow light spectral components of the first pixel;

determining an increase in yellow light spectral components from the quantum dot layer on the second light for a second pixel of the display based upon one or more of the backlight drive signals and a distance between the second pixel and at least one of the blue LED sources; and

adjusting a second LCD modulation drive signal for at least one subpixel of the second pixel based on the determining to reduce yellow light spectral components of the second pixel, wherein the adjusting of the first and the second LCD modulation drive signals occurs concurrently.

12. A method for driving a local-dimming display comprising:

emitting a first light by a plurality of individually controllable blue illumination sources onto a same quantum dot layer, the quantum dot layer formed as a plane;

converting the first light into second light by the quantum dot layer; and

compensating for an increase in yellow light spectral components from the quantum dot layer to the second light for a first pixel of the display by adjusting a first modulation drive signal for at least one subpixel of the first pixel based on a distance between the first pixel and at least one of the individually controllable blue illumination sources; and

compensating for an increase in yellow light spectral components from the quantum dot layer to the second light for a second pixel of the display by adjusting a second modulation drive signal for at least one subpixel of the second pixel based on a distance between the second pixel and at least one of the individually controllable blue illumination sources, wherein the adjusting of the first and the second modulation drive signals occurs concurrently.

13. The method claim 12 wherein the distance is related to one or more reflections of light from one of the individually controllable blue illumination sources.

14. An apparatus comprising:

a memory; and

a processor, the processor configured to

control a plurality of blue illumination sources of a backlight configured to emit first light onto one or more light conversion layers, the one or more light conversion layers formed as a plane, the one or more light conversion layers configured to be stimulated by the first light and to convert at least a portion of the first light into second light;

control one or more light modulators, the one or more light modulators configured to modulate light transmitting through individual subpixels;

perform at least one light field simulation for an increase in yellow light spectral components of the second light based on at least a distance between a first pixel of a display and at least one of the blue illumination sources and an increase in yellow light spectral components of the second light based on at least a distance between a second pixel of the display and at least one of the blue illumination sources; and

adjust a first and a second drive values for the one or more light modulators based on the at least one light field simulation for the first and the second pixels respectively, wherein the adjusting of the first and the second drive values occurs concurrently.

15. The apparatus of claim 14 further comprising logic to perform a light field simulation for non-uniformity of the blue illumination sources of the backlight.