Spoke light recapture in sequential color imaging systems

• US 6,324,006 B1
• Filed: 05/17/2000
• Issued: 11/27/2001
• Est. Priority Date: 05/17/1999
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Morgan, Daniel J.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): SEYRAFI, SAEED HMT
• Application Number:
  US09/572,470
• Time in Patent Office: 559 Days
• Field of Search: 359/618, 359/634, 359/639, 359/291, 359/72, 359/885, 359/298, 359/561, 359/589, 353/7, 353/29, 353/31, 353/32, 353/55, 353/84, 382/162, 382/167, 382/181, 348/742, 348/743
• US Class Current: 359/618
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 3/2025 the sub-frames having all the same time duration
• CPC Class Codes: G09G 3/2051 with use of a spatial dither pattern
• CPC Class Codes: G09G 3/2077 by a combination of two or more gradation control methods
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833
• CPC Class Codes: H04N 5/7416 involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal
• CPC Class Codes: H04N 5/7458 the modulator being an array of deformable mirrors, e.g. digital micromirror device [DMD]
• CPC Class Codes: H04N 9/22 using the same beam for more than one primary colour information H04N9/27 takes precedence
• CPC Class Codes: H04N 9/3114 by using a sequential colour filter producing one colour at a time
• CPC Class Codes: H04N 9/3182 Colour adjustment, e.g. white balance, shading or gamut white balance per se H04N9/73; control of amplitude of colour signals H04N9/68; colour control circuits for displays in general G09G5/02, G09G3/2003, G09G3/3607
• CPC Class Codes: H10K 59/351 comprising more than three subpixels, e.g. red-green-blue-white [RGBW]

Abstract

A method and display system for using the light (110) passing through the spokes of a color wheel (100). The light is a mixed and rapidly changing color. Adding all of the spoke times produces white, but adding a subset creates color artifacts. The spoke times cannot all be added at the same time without altering the white point of the display. The spoke times are added in a sequence and the sequence is altered over time for the same pixel such that the pixel converges to white over time. The pattern of spoke bits is arranged so that as adjacent spoke bit pixels are added, the net spoke light converges to white. The patterns are also varied so that as more and more spoke bit periods are turned on, the net spoke light converges to white. Each spoke bit period adds n-LSBs of white light intensity, so as each spoke bit period is added, n−1 LSBs of white light are subtracted from the white data.

Claims

1. A method of producing an image, said method comprising the steps of:

providing a sequential color beam of light, said sequential color beam of light changing color during each frame period, each frame period comprising;

at least two primary color periods; and

at least one spoke period during which said sequential color beam of light changes color;

modulating said sequential color beam of light during said primary color periods with primary color intensity data;

modulating said sequential color beam of light during at least one said spoke period with combined-color intensity data; and

focusing said modulated sequential color beam of light on an image plane to form a multi-color image.

2. The method of claim 1, said step of modulating said sequential color beam of light further comprising the step of modulating said sequential color beam of light during at least one said spoke period with white intensity data.

3. The method of claim 1, said step of modulating said sequential color beam of light further comprising the step of modulating said sequential color beam of light during at least one said spoke period with black intensity data.

4. The method of claim 1, wherein said at least two primary color periods comprises three primary color periods.

5. The method of claim 1, wherein said at least two primary color periods comprises a red, green, and blue primary color period.

6. The method of claim 1, wherein said at least two primary color periods comprises a red, green, blue, and white color period.

7. The method of claim 1, said step of modulating said sequential color beam of light during at least one said spoke period further comprises the step of splitting each said spoke period into two separately controlled spoke periods, and modulating said sequential color beam of light during each of said separately controlled spoke periods with different data.

8. The method of claim 1, said step of modulating said sequential color beam of light during at least one said spoke period further comprises the step of splitting each said spoke period into two separately controlled spoke periods, and incrementally enabling each of said spoke periods as said combined-color intensity data increases.

9. The method of claim 1, said step of modulating said sequential color beam of light during at least one said spoke period further comprises the step of splitting each said spoke period into two separately controlled spoke periods, and incrementally enabling each of said spoke periods as said combined-color intensity data increases.

10. The method of claim 9, said step incrementally enabling each of said spoke periods as said combined-color intensity data increases comprising the step of incrementally enabling each of said spoke periods in a sequence chosen to minimize color artifacts.

11. The method of claim 9, wherein at a given combined-color intensity data level the particular said spoke periods enabled varies over time.

12. A display system comprising:

a sequential color light source, said sequential color light source operable to provide a sequential color beam of light along a light path, said sequential color beam of light having;

at least two periods of primary color light each frame period; and

at least one spoke period during which said sequential color beam of light changes color;

a modulator disposed on said light path and operable to modulate said sequential color beam of light in response to image data received by said modulator; and

a controller operable to receive input intensity data and process said input intensity data to yield primary color output intensity data and combined color output intensity data, said controller transmitting said primary color output intensity data and said combined color output intensity data to said modulator such that said modulator modulates said sequential color beam of light with said primary color output intensity data during said at least two periods of primary color light and with said combined color output intensity data during said at least one spoke period.

13. The display system of claim 12, combined-color output intensity data representing the white intensity level.

14. The display system of claim 12, combined-color output intensity data representing the black intensity level.

15. The display system of claim 12, wherein said at least two periods of primary color light comprises three periods of primary color light.

16. The display system of claim 12, wherein said at least two periods of primary color light comprises a red, green, and blue primary color period.

17. The display system of claim 12, wherein said at least two periods of primary color light comprises a red, green, blue, and white color period.

18. The display system of claim 12, wherein each spoke period is divided into two spoke periods, said modulator using different data during each of said two spoke periods.