Display apparatus and method

• US 20060250336A1
• Filed: 05/02/2006
• Published: 11/09/2006
• Est. Priority Date: 01/31/1995
• Status: Active Grant

• Current Assignee: Lawson A. Wood
• Original Assignee: Lawson A. Wood
• Inventors: Wood, Lawson A.
• Granted Patent: US 7,782,280 B2
• Time in Patent Office: Days
• US Class Current: 345/84
• CPC Class Codes: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• 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 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/2007 Display of intermediate tones
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2025 the sub-frames having all the same time duration
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• CPC Class Codes: G09G 3/22 using controlled light sources
• CPC Class Codes: G09G 3/34 by control of light from an independent source
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals

Abstract

A display apparatus includes a spatial light modulator, such as a digital micromirror device or an LCD panel, and a lighting unit that illuminates the spatial light modulator. The lighting unit may include red, green, and blue lamps which emit light that impinges on a DMD from at least two different directions. The lamps may be flash tubes which are fired at different binary levels in accordance with the rank of the bits that are being displayed on the DMD. The lamps may be fluorescent lamps which are driven steadily at predetermined levels while the rows of micromirrors are turned on in sequence and subsequently turned off in sequence. Resetting to dislodge micromirrors that have become stuck can be accomplished by emitting current pulses through the micromirrors while exposing them to a magnetic field. The illumination unit may include a lamp unit and a color wheel. The light from the lamp unit can be integrated, and the data displayed on the spatial light modulator can be changed when the integrated light reaches a predetermined value. The color wheel may be rotated faster than the frame repetition rate of video information that is being displayed. The intensity of the light may be controlled in accordance with the bit rank or significance of the bits that are being displayed by the spatial light modulator. Several techniques for achieving different intensity levels are disclosed.

Claims

1. A method for displaying a first color component of an image described by video words for the first color component of a frame, the video words having bits with different bit ranks, said method comprising the steps of:

(a) for each bit rank of the first color component for a plurality of rows of the frame, turning pixels of a spatial light modulator on or off in accordance with values of the video words for the respective bit rank; and

(b) substantially steadily exposing the spatial light modulator to light that varies substantially in intensity while step (a) is being conducted.

2. The method of claim 1, wherein the light has an intensity at one moment that is at least about twice its intensity at another moment.

3. The method of claim 1, wherein the spatial light modulator comprises a digital micromirror device.

4. The method of claim 1, wherein step (b) comprises shining light generated by a light source onto the spatial light modulator, detecting the light, integrating the detected light, and changing the intensity of the light generated by the light source when the integrated light reaches a predetermined value.

5. A method for displaying a colored image that is generated by a digital micromirror device (DMD) having a plurality of micromirros which are movable between ON and OFF positions, the micromirrors being oriented to reflect light to a projection system when they are in their ON positions, said method comprising:

(a) supplying video data to the DMD for setting the positions of a first sub-set of the micromirrors;

(b) supplying additional video data to the DMD for setting the positions of a second sub-set of the micromirrors;

(c) exposing the DMD to light having a first color, the micromirrors of the first sub-set that are in their ON positions reflecting the light having the first color toward the projection system to form dots of the image; and

(d) exposing the DMD to light having a second color while step (c) is being conducted;

the micromirrors of the second sub-set that are in their ON positions reflecting the light having the second color toward the projection system to form additional dots of the image.

6. The method of claim 5, wherein the light having the first color impinges on the DMD from a first direction and the light having the second color component impinges on the DMD from a second direction that is substantially different from the first direction.

7. The method of claim 5, further comprising supplying further video data to the DMD for setting the positions of the first sub-set of micromirrors after step (a) has been conducted, and exposing the DMD to light having a third color, the micromirrors in the first sub-set that are set in their ON positions as a result of the further video data reflecting the light having a third color toward the projection system to form further dots of the image.

8. A method for use with a digital micromirror device (DMD) to display a sequence of image frames having a frame repetition rate, comprising:

(a) repeated supplying image data for first, second, and third color components to the DMD; and

(b) exposing the DMD to light having a sequence of intervals, the intervals including first color component intervals, second color component intervals, and third color component intervals, each interval of a given color component being preceded and followed by an interval of at least one of the other color components,

wherein step (b) is conducted so that intervals of the given color component impinge on the DMD at a rate substantially greater than about six times the frame repetition rate.

9. The method of claim 8, wherein the exposure in step (b) is substantially steady.

10. The method of claim 8, wherein step (b) comprises coloring light from a light source with a rotating color wheel.

11. The method of claim 8, wherein the sequence of intervals is a repeating sequence.

12. A method for displaying a colored image that is generated by a digital micromirror device (DMD), comprising:

(a) repeatedly supplying image data for first, second, and third color components to the DMD; and

(b) exposing the DMD to light having a first color that impinges on the DMD from a predetermined direction, to light having a second color that impinges on the DMD from the predetermined direction, and to light having a third color that impinges on the DMD from a direction different from the predetermined direction.

13. The method of claim 12, wherein step (b) comprises generating the light having a first color at a first location, generating the light having a second color at a second location, and directing at least some of the light having a first color and at least some of the light having a second color along a common path.