Spoke light recapture in sequential color imaging systems

• US 6,445,505 B1
• Filed: 11/27/2001
• Issued: 09/03/2002
• 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:
  US09/995,141
• Time in Patent Office: 280 Days
• Field of Search: 359/618, 359/722, 359/634, 359/639, 359/291, 359/298, 359/885, 359/561, 359/581, 359/589, 348/743, 348/742, 353/7, 353/29, 353/31, 353/32, 353/55, 353/84, 382/162, 382/167, 382/181
• 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 3/34 by control of light from an independent source
• 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−I 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;

determining a desired intensity value for each of said primary colors and a combined-color value;

assigning an amount of said combined color value to be created using said spoke periods to a spoke intensity value;

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

modulating said sequential color beam of light during at least one said spoke period with said spoke intensity value; 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 modulating said sequential color beam of light during at least one said spoke period comprising:

assigning each data bit of said spoke intensity value to at least one said spoke period such that light during a given portion of a spoke period is focused on said image plane when a corresponding bit of said spoke intensity value is active.

3. The method of claim 2, said assigning comprising at least two data bits to a particular spoke period.

4. The method of claim 3, said assigning comprising one data bit to at least two spoke periods.

5. A method of producing white light in an image pixel, comprising:

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;

providing a desired intensity and color value for an image pixel;

determining a combined color content value of said desired intensity and color value;

allocating at least a portion of said combined color content value to a spoke period value; and

enabling a modulator to utilize said sequential color beam of light during at least one said spoke period to form said image pixel dependent on said spoke period value.

6. The method of claim 5, comprising:

said frame period comprising at least one white period during which said sequential beam of light is white light;

allocating at least a portion of said combined color content value to a white period value; and

enabling a modulator to utilize said sequential color beam of light during at least one said white period to form said image pixel dependent on said white period value.

7. The method of claim 5, comprising:

said frame period comprising at least one white period during which said sequential beam of light is white light;

allocating at least a portion of said combined color content value to a white period value; and

enabling a modulator to utilize said sequential color beam of light during at least one said white period to form said image pixel dependent on said white period value, said enabling performed using spatial temporal modulation.

8. The method of claim 5, comprising:

allocating at least a portion of said combined color content value to a primary period value for each primary color period; and

enabling a modulator to utilize said sequential color beam of light during said primary color periods to form said image pixel dependent on said primary period values.

9. The method of claims 5, comprising:

reducing an intensity value for at least one primary color period based on said combined content value.

10. The method of claim 5, comprising:

reducing an intensity value for at least two primary color periods based on said combined content value, at least one primary color intensity value reduced unequally relative to another primary color intensity value.

11. The method of claim 5, comprising:

reducing an intensity value for at least two primary color periods based on said combined content value, at least one primary color intensity value reduced unequally relative to another primary color intensity value to correct the color of said pixel.