White point uniformity techniques for displays

Patent metadata

Field	Value
Publication number	US-9940879-B2
Application number	US-201113253739-A
Country	US
Kind code	B2
Filing date	Oct 5, 2011
Priority date	Oct 5, 2011
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

The present disclosure generally relates to systems and techniques for calibrating displays to improve the white point uniformity between similar type devices. In one embodiment, a backlight includes multiple strings of LEDs, where each string is driven by a separate driver, or driver channel. Each string may be separately tested at a base current to determine its emitted chromaticity, and values indicative of the emitted chromaticities may be stored within the backlight as calibration values. The calibration values may then be used to determine the driving strength for each string that allows the display to produce the target white point when the light from the strings is mixed. Further, in certain embodiments, adjustments also may be made to the LCD panel based on the emitted chromaticities at the base current.

First claim

What is claimed is:

1. A display, comprising:
a first string of first light emitting diodes;
a second string of second light emitting diodes;
a storage containing calibration values representing a first emitted chromaticity of the first string when driven at a base current in isolation and a second emitted chromaticity of the second string when driven at the base current in isolation; and
a controller configured to determine a first driving strength for the first string and a second driving strength for the second string based on the calibration values, wherein the calibration values comprise a first set of chromaticity coordinates representing the first emitted chromaticity and a second set of chromaticity coordinates representing the second emitted chromaticity.

2. A display, comprising:
a first string of first light emitting diodes;
a second string of second light emitting diodes;
a storage containing calibration values representing a first emitted chromaticity of the first string when driven at a base current in isolation and a second emitted chromaticity of the second string when driven at the base current in isolation; and
a controller configured to determine a first driving strength for the first string and a second driving strength for the second string based on the calibration values, wherein the calibration values comprise a set of chromaticity coordinates representing a mixed chromaticity of the first emitted chromaticity and the second emitted chromaticity.

3. A method, comprising:
storing, in a storage of an electronic device comprising a backlight, calibration values representing emitted chromaticities for each of a plurality of strings of light emitting diodes driven at a base current in isolation; and
configuring a controller of the electronic device to determine individual driving strengths for each of the plurality of strings based on the calibration values, wherein the individual driving strengths are configured to align a mixed chromaticity for the plurality of strings with a target white point, wherein storing calibration values comprises storing sets of chromaticity coordinates and brightness values for each of the emitted chromaticities.

Assignees

• Gettemy Shawn Robert
• Wurzel Joshua Grey
• Guillou Jean Pierre Simon
• Xu Ming
• Doyle David Andrew
• Apple Inc

Inventors

• Gettemy Shawn Robert
• Wurzel Joshua Grey
• Guillou Jean-Pierre Simon
• Xu Ming
• Doyle David Andrew

Classifications

• G09G2360/145

  the light originating from the display screen · CPC title

• G09G2320/0666

  for control of colour parameters, e.g. colour temperature · CPC title

• G09G3/3406 Primary

  Control of illumination source (illumination devices structurally associated with liquid crystal cells G02F1/1336) · CPC title

• G09G2320/0646

  Modulation of illumination source brightness and image signal correlated to each other · CPC title