Coordinating backlight frequency and refresh rate in a panel display

• US 20050068289A1
• Filed: 09/30/2003
• Published: 03/31/2005
• Est. Priority Date: 09/30/2003
• Status: Active Grant

• Current Assignee: Tahoe Research Limited (f/k/a Learndale Limited) (Vector Capital Corporation)
• Original Assignee: Intel Corporation
• Inventors: Wyatt, David, Diefenbaugh, Paul S.
• Granted Patent: US 7,233,309 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/06 Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A panel may be arranged to display image data, and a backlight may be arranged to illuminate a back of the panel. A timing generator may be arranged to control the refresh rate of the panel, and a modulator may be arranged to control the backlight based on an associated modulation frequency. A coordinator may be arranged to synchronize between the refresh rate and the modulation frequency when the refresh rate or the modulation frequency is changed.

Claims

1. A system, comprising:

a timing generator to control a refresh rate of a display;

a modulator to control a backlight frequency of a backlight; and

a display driver connected to the timing generator and the modulator to adjust the backlight frequency of the backlight based on the refresh rate of the display.

2. The system of claim 1, wherein the timing generator is arranged to produce at least one refresh rate of the display.

3. The system of claim 1, further comprising:

a buffer connected to the timing generator to output display data at the refresh rate of the display.

4. The system of claim 3, further comprising:

an encoder connected to the buffer to encode the output the display data from the buffer for presentation on the display.

5. The system of claim 1, wherein the modulator includes a pulse width modulator to operate at a modulation frequency that is controlled by the display driver.

6. The system of claim 5, further comprising:

an inverter connected between the modulator and the backlight to operate the backlight at the backlight frequency based on the modulation frequency of the modulator.

7. The system of claim 1, wherein the display driver is arranged to adjust the backlight frequency of the backlight to be an integer multiple the refresh rate of the display.

8. The system of claim 1, wherein the display driver is arranged to adjust the backlight frequency of the backlight so that a beat frequency between the backlight frequency and the refresh rate of the display is greater than about 100 Hz.

9. A method of controlling a display that includes a backlight, comprising:

changing an original refresh rate of the display to a new refresh rate;

determining a desired modulation frequency for the backlight based on the new refresh rate of the display; and

adjusting a frequency of the backlight to the desired modulation frequency.

10. The method of claim 9, wherein the changing includes:

lowering the refresh rate of the display to the new refresh rate that is different than the original refresh rate.

11. The method of claim 9, wherein the determining includes:

obtaining the desired backlight frequency that is a multiple of the new refresh rate.

12. The method of claim 9, wherein the determining includes:

obtaining the desired backlight frequency so that a beat frequency between the desired backlight frequency and the new refresh rate is too high to be visually perceived by a user of the display.

13. The method of claim 9, wherein the determining includes:

ascertaining a desired modulation frequency for a modulator connected to the backlight that will produce the desired backlight frequency for the backlight.

14. The method of claim 13, wherein the adjusting includes:

controlling the modulator to produce the desired modulation frequency.

15. A system, comprising:

a panel to display image data thereon;

a backlight to illuminate a rear of the panel;

a timing generator to control a refresh rate of the panel;

a modulator to control the backlight based on an associated modulation frequency;

a coordinator to coordinate between the refresh rate and the modulation frequency when the refresh rate or the modulation frequency is changed; and

an antenna proximate the panel.

16. The system of claim 15, further comprising:

an audio device proximate the panel.

17. The system of claim 15, further comprising:

a communication interface proximate the panel.

18. The system of claim 15, wherein the coordinator is arranged to control the timing generator and the modulator to result in one of the refresh rate and the modulation frequency being a multiple of another of the refresh rate and the modulation frequency.

19. The system of claim 15, wherein the coordinator is arranged to control the timing generator and the modulator to result in a beat frequency between the refresh rate and the modulation frequency being too high to be visually detected by a user of the system.

20. A system, comprising:

means for controlling a refresh rate of a panel;

means for adjusting an operational frequency of a backlight; and

means for coordinating between the means for controlling and the means for adjusting to substantially avoid a beat frequency between the refresh rate and the operational frequency that is visually perceptible by a user of the system.

21. The system of claim 20, wherein the means for coordinating further coordinates between the means for controlling and the means for adjusting to substantially match the beat frequency and the refresh rate.

22. The system of claim 20, wherein the means for coordinating further coordinates between the means for controlling and the means for adjusting so that the beat frequency is too high to be visually perceived by the user of the system.