DISPLAY APPARATUS UTILIZING INDEPENDENT CONTROL OF LIGHT SOURCES FOR UNIFORM BACKLIGHT OUTPUT

• US 20140253562A1
• Filed: 03/06/2013
• Published: 09/11/2014
• Est. Priority Date: 03/06/2013
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Pixtronix, Incorporated (Qualcomm, Inc.)
• Inventors: Yaras, Fahri
• Granted Patent: US 9,301,369 B2
• Time in Patent Office: Days
• US Class Current: 345/501
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• 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 5/10 Intensity circuits
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: H05B 47/165 following a pre-assigned programmed sequence; Logic control [LC]

Abstract

This disclosure provides systems, methods and apparatus for improving light output resolution of a backlight by individually controlling light sources in the backlight. Illumination intensity levels of light sources are individually controlled such that an overall illumination intensity level of all the light sources is substantially equal to a desired whole backlight illumination intensity value. The individual illumination levels of the light sources or a group of the light sources is controlled such that the backlight is uniformly illuminated. In some implementations, the illumination intensity levels are varied over different portions of an illumination period to provide uniform illumination of the backlight.

Claims

1. An apparatus, comprising:

a backlight;

a plurality of light sources associated with a first color; and

illumination control logic coupled to the plurality of light sources configured to;

independently control a number of groups of the light sources to output a plurality of discrete output illumination intensity levels,

receive an input signal indicating a discrete whole backlight illumination intensity value for the first color to be output by the backlight, and

in response to the input signal indicating a whole backlight illumination intensity value that is not an integer multiple of the number of groups, controlling at least one of the groups to be illuminated at a lesser intensity level than a remainder of the groups such that an illumination output of the backlight is substantially uniform across its surface and the total illumination intensity level of the groups of light sources is substantially equal to the whole backlight illumination intensity value indicated in the received input signal.

2. The apparatus of claim 1, wherein the lesser intensity level is less than the intensity level of the remainder of groups of light sources by only a single discrete illumination intensity level.

3. The apparatus of claim 1, wherein the illumination control logic is further configured to illuminate up to one-half the number of independently controlled groups of light sources at the lesser intensity level.

4. The apparatus of claim 1, wherein the illumination logic is configured, to switch the at least one group of light sources outputting the lesser illumination level to a second set of the at least one group of light sources.

5. The apparatus of claim 1, wherein the illumination logic is configured to cause the at least one group of light sources to be illuminated at the lesser illumination intensity for less than an entirety of a period of time, and at a greater intensity for the remainder of the period of time, while maintaining the total illumination intensity level of the groups of light sources to be substantially equal to the whole backlight illumination intensity value for the period of time.

6. The apparatus of claim 5, wherein the at least one group of light sources includes all of the groups of light sources.

7. The apparatus of claim 1, wherein each group of light sources includes only one light source.

8. The apparatus of claim 1, wherein the light sources comprise light emitting diodes (LEDs).

9. The apparatus of claim 1, further comprising:

a display including;

the backlight,

the plurality of light sources, and

illumination control logic;

a processor that is configured to communicate with the display, the processor being configured to process image data; and

a memory device that is configured to communicate with the processor.

10. The apparatus of claim 9, the display further including:

a driver circuit configured to send at least one signal to the display; and

a controller configured to send at least a portion of the image data to the driver circuit.

11. The apparatus of claim 9, the display further including:

an image source module configured to send the image data to the processor, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

12. The apparatus of claim 9, the display further including:

an input device configured to receive input data and to communicate the input data to the processor.

13. A method, comprising:

receiving an input signal indicating a discrete whole backlight illumination intensity value for a first color to be output by a backlight having a plurality of light sources of the first color; and

in response to receiving the input signal indicating the whole backlight illumination intensity value that is not an integer multiple of a number of independently controlled groups of the plurality of light sources, independently controlling at least one of the number of groups to be illuminated at a lesser illumination intensity level than that of a remainder of the groups such that an illumination output of the backlight is substantially uniform across its surface and a total illumination intensity level of the number of groups is substantially equal to the whole backlight illumination intensity value indicated in the received input signal.

14. The method of claim 13, wherein the lesser intensity level is less than the intensity level of the remainder of groups of light sources by only a single discrete illumination intensity level.

15. The method of claim 13, wherein the at least one of the number of groups includes one half of the total number of groups.

16. The method of claim 13, further comprising:

switching the at least one of the number of groups outputting the lesser illumination level to a second set of at least one of the number of groups while maintaining the total illumination intensity level of the groups of light sources to be equal to the whole backlight illumination intensity value.

17. The method of claim 13, further comprising:

maintaining the total illumination intensity level of the groups of light sources to be equal to the whole backlight illumination intensity value for a period of time, and

controlling the at least one of the number of groups to be illuminated at the lesser illumination intensity level for less than the entirety of the period of time and at a greater intensity for the remainder of the period of time.

18. The method of claim 13, wherein the at least one of the number of groups includes all of the plurality of light sources.

19. The method of claim 13, wherein each of the number of groups includes only one light source.

20. The method of claim 13, wherein the plurality of light sources include light emitting diodes.