Display operation with inserted block clears

• US 6,778,155 B2
• Filed: 07/31/2001
• Issued: 08/17/2004
• Est. Priority Date: 07/31/2000
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Hewlett, Gregory J., Doherty, Donald B.
• Primary Examiner(s): Eisen, Alexander
• Application Number:
  US09/918,837
• Publication Number:
  US 20020012000A1
• Time in Patent Office: 1,113 Days
• Field of Search: 345/84, 345/85, 359/223, 359/237, 359/238, 359/290, 359/291, 348/739, 348/744, 348/750
• US Class Current: 345/85
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2320/0266 Reduction of sub-frame artefacts
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2033 with splitting one or more sub-frames corresponding to the most significant bits into two or more sub-frames
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833

Abstract

An SLM PWM clocking method, called “jog clear,” for generating short bit periods where block data clears (74) are inserted between block data loads (72, 76) within a frame refresh period. The method significantly reduces the short bit duration that requires use of the earlier reset-release method and it eliminates undesirable artifacts present in these earlier SLM clocking methods.

Claims

1. A method of operating an SLM, said method comprising:

loading a first bit of display data in a block of SLM elements;

resetting said SLM elements to display said first bit of display data;

loading clear data in said block of SLM elements, said clear data loaded into groups of said SLM elements such that said step of loading clear data takes less time than said step of loading said first bit of display data;

resetting said SLM elements to display said clear data;

loading a second bit of display data in said block of SLM elements;

resetting said block of SLM elements to display said second bit of display data; and

wherein a duration during which a bit of display data displayed prior to said first bit of display data is not the same for all blocks and said display duration of said prior bit is equalized over a frame period by reloading and displaying said prior and said second bits of display data consecutively in an opposite order at another time during said frame period.

2. The method of claim 1, said first bit of display data displayed for a duration less than a sum of an element settling time and a block load time.

3. The method of claim 1, wherein said clear data latches said elements in an OFF state.

4. The method of claim 3, wherein elements remain in said OFF state while a subsequent bit of display data is loaded into said elements.

5. The method of claim 1, further comprising the step of selecting a current block to load.

6. The method of claim 1, further comprising the step of selecting a current block to load by incrementing or decrementing a block address.

7. The method of claim 5, further comprising the step of selecting a current block to load supplying a block address signal.

8. The method of claim 1, further comprising the steps of:

loading a first bit of display data in at least one additional block of SLM elements;

resetting said additional block of SLM elements to display said first bit of display data;

loading clear data in said additional block of SLM elements; and

resetting said additional block of SLM elements to display said clear data.

9. The method of claim 8, further comprising the step of loading some, but not all, of said additional blocks with a second bit of display data prior to resetting all of said blocks to display said clear data.

10. The method of claim 1, wherein said display duration of said prior bit is different for each of said blocks.

11. The method of claim 1, wherein said display duration of said prior bit for each given block is longer than said display duration of said prior bit for each block reset prior to said given block.

12. The method of claim 1, wherein said display duration of said prior bit is equalized over a frame period by reloading said prior bit of display data as said second bit of display data.

13. The method of claim 1, wherein said display duration of said prior bit is equalized over a frame period by reloading and displaying said prior and said second bits of display data in an opposite order at another time during said frame period separated by another bit that is loaded, reset, and followed by a clear period in the same manner as said first bit.

14. The method of claim 8, wherein some, but not all, of said additional blocks of SLM elements are loaded with said clear data prior to resetting all of said blocks to display said first bit of display data.

15. The method of claim 14, wherein a duration during which a bit of display data displayed prior to said first bit of display data is not the same for all blocks.

16. The method of claim 15, wherein said display duration of said prior bit is different for each of said blocks.

17. The method of claim 15, wherein said display duration of said prior bit for each given block is longer than said display duration of said prior bit for each block reset prior to said given block.

18. The method of claim 15, wherein said display duration of said prior bit is equalized over a frame period by reloading said prior bit of display data as said second bit of display data.

19. A projection display comprising:

a light source for producing a beam of light along a first light path;

control electronics for receiving image data and providing control signals and display data representing said image data; and

a spatial light modulator on said first light path for receiving said control signals and said display data and for selectively modulating said beam of light in response to display data, said spatial light modulator comprised of and array of modulator elements, said modulator elements grouped into at least two blocks;

said control electronics operable to;

load a first bit of display data in a first of said blocks, reset said first of said blocks to display loaded data, and load clear data in said first block, said clear data loaded into said first block faster than said first bit of said display data, wherein some of additional blocks of modulator elements are loaded with a second bit of display data prior to resetting all of said blocks to display said clear data said control electronics operable to display a bit prior to said first bit of display data for a duration, said duration of said prior bit not the same for all said blocks said control electronics operable to compensate said duration of said prior bit and a duration of a second bit of display data displayed immediately after said clear data over a frame period by reloading said prior and said second bits of display data in an opposite order at another time during said frame period.

20. The display system of claim 19, said control electronics further operable to loading some, but not all, of said additional blocks with a second bit of display data prior to resetting all of said blocks to display said clear data.

21. The display system of claim 19, said control electronics further operable to compensate said duration of said prior bit by reloading said prior bit following said clear data.

22. The display system of claim 19, said control electronics further operable to compensate said duration of said prior bit and a duration of a second bit of display data displayed immediately after said clear data over a frame period by reloading said prior and said second bits of display data in an opposite order at another time during said frame period separated by another bit that is loaded, reset, and followed by a clear period in the same manner as said first bit.

23. A projection display comprising:

a light source for producing a beam of light along a first light path;

control electronics for receiving image data and providing control signals and display data representing said image data; and

a spatial light modulator on said first light path for receiving said control signals and said display data and for selectively modulating said beam of light in response to display data, said spatial light modulator comprised of and array of modulator elements, said modulator elements grouped into at least two blocks;

said control electronics operable to;

load a first bit of display data in a first of said blocks, reset said first of said blocks to display loaded data, and load clear data in said first block, said clear data loaded into said first block faster than said first bit of said display data, wherein some, but not all, of additional blocks of modulator elements are loaded with said clear data prior to resetting all of said blocks to display said first bit of display data, said control electronics further operable to compensate said duration of said prior bit and a duration of a second bit of display data displayed immediately after said clear data over a frame period by reloading said prior and said second bits of display data in an opposite order at another time during said frame period.

24. The display system of claim 23, said control electronics further operable to loading some, but not all, of said additional blocks with a second bit of display data prior to resetting all of said blocks to display sad clear data.

25. The display system of claim 23, said control electronics further operable to display a bit prior to said first bit of display data for a duration, said duration of said prior bit not the same for all said blocks.

26. The display system of claim 23, said control electronics further operable to compensate said duration of said prior bit by reloading said prior bit following said clear data.

27. The display system of claim 23, said control electronics further operable to compensate said duration of said prior bit and a duration of a second bit of display data displayed immediately after said clear data over a frame period by reloading said prior and said second bits of display data in an opposite order at another time during said frame period separated by another bit that is loaded, reset, and followed by a clear period in the same manner as said first bit.