Signal generator for controlling a spatial light modulator

• US 5,581,272 A
• Filed: 08/25/1993
• Issued: 12/03/1996
• Est. Priority Date: 08/25/1993
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Kornher, Kevin, Overlaur, Michael J., Conner, James L.
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Saras, Steven J.
• Application Number:
  US08/111,696
• Time in Patent Office: 1,196 Days
• Field of Search: 345/84, 345/85, 345/206, 345/132, 345/75, 345/76, 345/98, 345/108, 345/97, 348/770, 348/771, 348/755, 348/756, 348/757, 348/758, 348/762, 348/764
• US Class Current: 345/85
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2310/0289 Details of voltage level shifters arranged for use in a driving circuit
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833

Abstract

A method and device for controlling the bias voltages for a split-reset spatial light modulator. Each block of the spatial light modulator can be individually controlled lowering the throughput needed to load each frame of data. Blocks are selected individually or in groups with the potential of providing one voltage condition on the selected blocks and a different voltage condition on the deselected blocks. One embodiment of the disclosed method comprises input latches and buffers 44, address decode logic 46 to determine the selected blocks, mode select logic 48 to determine the requested operation, delay circuitry 50 to minimize current loading, and level shifters 52 to convert logic signals to voltage levels appropriate to control the output drive circuitry 54.

Claims

1. A signal generator for controlling a spatial light modulator, wherein said spatial light modulator is comprised of blocks of modulator elements, comprising:

a block selector to select at least one block of said spatial light modulator; and

an output drive connected to said block selector and to each block of said spatial light modulator to simultaneously provide a reset signal to said at least one selected block of said spatial light modulator and a hold signal to each unselected block of said spatial light modulator, whereby said modulator elements in said selected blocks of said spatial light modulator elements are reset while said modulator elements in said unselected blocks continue to hold data.

2. The signal generator of claim 1 wherein said output drive includes means for switching a voltage to each block of said spatial light modulator.

3. The signal generator of claim 1 wherein said output drive comprises at least one transistor to switch a voltage to each block of said spatial light modulator.

4. The signal generator of claim 1 wherein said block selector simultaneously selects all even numbered blocks.

5. The signal generator of claim 1 wherein said block selector simultaneously selects all odd numbered blocks.

6. The signal generator of claim 1 wherein said block selector simultaneously selects all said blocks.

7. The signal generator of claim 1 wherein said block selector selects an individual block determined by an address input to said block selector.

8. The signal generator of claim 1 further comprising a delay block to ensure that said output drive stops providing a first voltage before providing a second voltage.

9. The signal generator of claim 1 further comprising a level shifter to shift the voltage level of the signals controlling said output drive to the voltage levels necessary to properly bias the output drive transistors.

10. The signal generator of claim 1 wherein said reset signal comprises a voltage oscillating between two levels.

11. The signal generator of claim 10 wherein said oscillation is performed at a rate determined by an external clock.

12. A signal generator for controlling a spatial light modulator, wherein said spatial light modulator is comprised of blocks, comprising:

a block selection decoder to select at least one block of said spatial light modulator, said block selection decoder enabling the selection of either all even numbered blocks simultaneously, all odd numbered blocks simultaneously, all blocks simultaneously, or one block individually, said selection based on address and block select signals input to said block selection decoder;

a mode selection decoder to determine what operation should be performed on each selected block and each non-selected block, said determination based on mode select signals input to said mode select decoder and whether or not each block is selected as determined by the output of said block selection decoder;

a delay circuit to ensure that said output drive circuit stops driving the control or bias signals necessary to perform one operation before supplying the control or bias signals necessary to perform a second operation;

a level shifter circuit to shift the voltage level of the signals controlling said output drive to the voltage levels necessary to properly bias the output drive transistors; and

an output drive circuit connected to said mode selection decoder and to each block of said spatial light modulator to supply the control or bias signals necessary to perform said operations on said blocks, said output drive comprising at least one transistor to switch a bias voltage to each block of said spatial light modulator.

13. A method of controlling a spatial light modulator, wherein said spatial light modulator is comprised of at least two groups of modulator elements, said method comprising:

providing block select and mode select signals;

decoding said block select signals to select at least one said groups of modulator elements;

decoding said block select signals to determine which of said groups of modulator elements are selected to receive an element reset signal; and

providing an element reset signal to said groups of modulator elements selected to receive said element reset signal while simultaneously providing a different voltage signal to a remainder of said groups of modulator elements.

14. The method of Claim 13 wherein said step of providing an element reset signal is comprised of providing an oscillating voltage signal to said groups of modulator elements selected to receive said element reset signal.

15. The method of Claim 15 wherein said step of simultaneously providing a different voltage signal is comprised of providing a hold signal to said remainder of said groups of modulator elements whereby data being displayed by said remainder of said groups of

modulator elements continues to be displayed while said groups of modulator elements selected to receive said element reset signal are reset.