System and method for displaying images

• US 20070200806A1
• Filed: 02/24/2006
• Published: 08/30/2007
• Est. Priority Date: 02/24/2006
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Bellis, Harold, Vestal, Gregory
• Granted Patent: US 7,623,286 B2
• Time in Patent Office: Days
• US Class Current: 345/85
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 3/2025 the sub-frames having all the same time duration
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources

Abstract

System and method for enhancing image quality in a display system. A preferred embodiment comprises a variable light source capable of producing a light of specified intensity and color, an array of light modulators optically coupled to the variable light source, the array to modulate the light based upon image data to display images on a display plane, a controller coupled to the array, the controller to issue commands to control the array, and a light driver circuit coupled to the variable light source and the controller, the light driver circuit to provide a signal to the variable light source to specify the intensity of the light produced by the variable light source, when there is a change in a color of light being displayed or when a change in a weight of the image data to be displayed requires less light to be displayed than a current output level.

Claims

1. A method for displaying image data, the method comprising:

determining that a change in a light source output is needed when there is a change in the color of light being displayed or when there is a change in a weight of the image data to be displayed;

adjusting the light source output in response to the determining;

illuminating an array of light modulators with the light source output; and

setting light modulators in the array of light modulators based on the image data.

2. The method of claim 1, wherein the setting further comprises displaying the image data, and wherein the method further comprises after the adjusting and before the setting, waiting for the output of the light source to stabilize.

3. The method of claim 1 further comprising after the setting:

waiting for the output of the light source to stabilize; and

displaying the image data.

4. The method of claim 1, wherein the adjusting comprises changing a drive current to the light source.

5. The method of claim 1, wherein the light source comprises a plurality of lamps, and wherein the adjusting comprises turning on lamps in the light source or turning off lamps in the light source.

6. A method for displaying an image in a display system, wherein the image comprises more than one set of image data, the method comprising:

determining that a change in a light source output is needed when there is a change in the color of light being displayed or when there is a change in a weight of the image data to be displayed;

adjusting the light source output in response to the determining;

illuminating an array of light modulators with the light source output;

setting light modulators in the array of light modulators based on the image data; and

repeating the adjusting and the setting in response to a determination that an additional set of image data is to be displayed.

7. The method of claim 6 further comprising after the setting, repeating the setting in response to a determination that an additional set of image data can be displayed without adjusting the light source output.

8. The method of claim 6, wherein the adjusting comprises providing drive signals to a light source drive circuit to cause the light source to produce a light output that comprises a sequence of pulses, wherein the pulses are a function of a color of light being displayed.

9. The method of claim 8, wherein a boosted pulse comprises a pulse of light with greater light output intensity than an average light output intensity of the light source, wherein the sequence of pulses comprises a boosted pulse for at least one color of light being displayed.

10. The method of claim 9, wherein the sequence of pulses comprises a boosted pulse each time the one color of light is being displayed.

11. The method of claim 8, wherein a negative pulse for a color of light comprises a pulse of light with a light output that is a fraction of a light output intensity of a light output pulse associated with the color of light, and wherein the sequence of pulses comprises a negative pulse for at least one color of light being displayed.

12. The method of claim 11, wherein the negative pulse comprises a pulse of one-half or one-quarter the light output intensity of the light output pulse associated with the color of light.

13. The method of claim 11, wherein a duration of a negative pulse for the color of light is a fraction of a duration of the light output pulse associated the color of light.

14. The method of claim 8, wherein an average of the light output from the light source over a period of time is substantially equal to a rated output level of the light source.

15. The method of claim 14, wherein a frame duration is an amount of time required to display an image, and wherein the period of time comprises at least one frame duration.

16. The method of claim 8, wherein the sequence of pulses is periodic with a period equal to an amount of time required to display an image or a sub-image.

17. A display system comprising:

a variable light source capable of producing a light of specified intensity and color;

an array of light modulators optically coupled to the variable light source, the array of light modulators configured to modulate the light produced by the variable light source based upon image data to display images on a display plane;

a controller coupled to the array of light modulators, the controller configured to issue commands to control the operation of the array of light modulators and

a light driver circuit coupled to the variable light source and the controller, the light driver circuit configured to provide a signal to the variable light source to result in the variable light source producing a light of the specified intensity, when there is a change in a color of light being displayed or when a change in a weight of the image data to be displayed requires an amount of light to be displayed that is less than a current output level.

18. The display system of claim 17, wherein the variable light source comprises a wide-band lamp, and wherein the display system further comprises a color filter optically coupled between the variable light source and the array of light modulators, the color filter configured to filter the light produced by the variable light source to sequentially produce light of desired colors.

19. The display system of claim 18, wherein the controller issues signals to the light driver circuit to inform the light driver circuit of color filter state changes, and wherein the light driver circuit changes the intensity of the light produced by the variable light source at least once during a time period used to display an image.

20. The display system of claim 19, wherein the light driver circuit reduces the intensity of the light produced by the variable light source to a level that is a fraction of an average intensity of light produced by the variable light source.

21. The display system of claim 17, wherein the variable light source comprises a plurality of rapid switching lights, and wherein the light driver circuit changes the intensity of the light produced by the variable light source by changing a number of rapid switching lights that are on.

22. The display system of claim 17, wherein the variable light source comprises a lamp selected from the group consisting of:

an arc lamp, a light emitting diode, a phosphor coated light emitting diode, and a laser.

23. The display system of claim 17, wherein the array of light modulators is a digital micromirror device.

24. The display system of claim 17, wherein the array of light modulators is a liquid crystal display.