Techniques for dual modulation with light conversion

• US 9,810,944 B2
• Filed: 08/20/2015
• Issued: 11/07/2017
• Est. Priority Date: 08/21/2014
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Wan, Chun Chi, Ninan, Ajit
• Primary Examiner(s): A, Minh D
• Application Number:
  US15/505,432
• Publication Number:
  US 20170242301A1
• Time in Patent Office: 810 Days
• CPC Class Codes: G02F 1/133601 for spatial active dimming
• CPC Class Codes: G02F 1/133609 including means for improving the color mixing, e.g. white
• 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 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 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

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, such as blue or ultraviolet light, into second light, such as white light. The light conversion layer can include quantum dot materials. Liquid crystal display (LCD) modulation drive signals are generated to determine transmission of the second light through individual color subpixels of the display. These LCD modulation drive signals can be adjusted based on one or more light field simulations to account for non-uniform, spatial color shifts. Alternatively, one or more light field simulations based on a uniformity assumption determine intermediate LCD modulation drive signals. A compensation field simulation, using backlight drive signals, is then used to adjust the intermediate LCD modulation drive signal for color correction.

Claims

1. An apparatus comprising:

logic controlling one or more illumination sources of a backlight configured to emit first light onto one or more light conversion layers, 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;

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

logic to perform at least one light field simulation for a backlight point spread function to determine intermediate drive values for the one or more light modulators;

logic to determine a compensation light field to adjust the intermediate drive values for the one or more light modulators to mitigate spatial non-uniformity of the second light.

2. The apparatus of claim 1 further comprising logic to adjust the intermediate drive values, the logic to adjust the intermediate drive values comprising at least one of a scaler and lookup table.

3. The apparatus of claim 1 wherein the second light is a broad spectrum light.

4. The apparatus of claim 1 wherein the second light comprises of a combination of frequencies in red, blue and green portions of a visible spectrum.

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

emitting first light by one or more individually controllable illumination sources onto a quantum dot layer, the first light including at least one of UV spectral components or blue light spectral components;

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

determining intermediate liquid crystal display modulation drive signals by one or more light field simulations;

determining a compensation field for spatial color non-uniformity related to traveling distances of light from one or more illumination sources; and

compensating for the spatial color non-uniformity by adjusting the intermediate liquid crystal display modulation drive signals.

6. The method claim 5 wherein the traveling distances account for one or more reflections.

7. An apparatus comprising a processor and configured to perform the method recited in claim 5.