Operating method for active matrix addressed bistable reflective cholesteric displays

• US 20010050666A1
• Filed: 04/18/2001
• Published: 12/13/2001
• Est. Priority Date: 04/27/2000
• Status: Active Grant

• Current Assignee: Manning Ventures, Inc.
• Original Assignee: Manning Ventures, Inc.
• Inventors: Huang, Xiao-Yang, Miller, Nick Martin IV
• Granted Patent: US 6,850,217 B2
• Time in Patent Office: Days
• US Class Current: 345/88
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G09G 2300/0486 Cholesteric liquid crystals, including chiral-nematic liquid crystals, with transitions between focal conic, planar, and homeotropic states
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 3/3651 using multistable liquid crystals, e.g. ferroelectric liquid crystals
• CPC Class Codes: G09G 5/363 Graphics controllers

Abstract

An operating method for a color display system including an active matrix bistable liquid crystal display (LCD) having a plurality of pixels arranged in a matrix based on color data and status bits corresponding to each of the pixels stored in a memory includes steps for generating voltage data corresponding to the pixels based on the color data and the status bits stored for each of the pixels, converting the voltage data to drive signals suitable for driving the active matrix bistable LCD, and applying the drive signals to the active matrix bistable LCD. In an exemplary embodiment, the active matrix bistable LCD is a Cholesteric LCD. Advantageously, the generating, converting, and applying steps are repeated for a corresponding pixel N times, where N is an integer established by the status bits.

Claims

1. An operating method for a color display system including an active matrix bistable liquid crystal display (LCD) having a plurality of pixels arranged in a matrix based on color data and status bits corresponding to each of the pixels stored in a memory, comprising:

generating voltage data corresponding to the pixels based on the color data and the status bits stored for each of the pixels;

converting the voltage data to drive signals suitable for driving the active matrix bistable LCD; and

applying the drive signals to the active matrix bistable LCD.

2. The method as recited in

claim 1

, wherein the active matrix bistable LCD comprises a Cholesteric LCD.

3. The method as recited in

claim 1

, wherein the generating step is performed when the status bits for the respective one of the pixels correspond to a non-zero binary number.

4. The method as recited in

claim 1

, wherein the generating, converting, and applying steps are repeated for a corresponding pixel N times, where N is an integer established by the status bits.

5. An operating method for a color display system including an active matrix bistable liquid crystal display (LCD) having a plurality of pixels arranged in a matrix, comprising:

storing color data and status bits corresponding to each of the pixels;

generating voltage data corresponding to the pixels based on the color data and the status bits stored for each of the pixels;

converting the voltage data to drive signals suitable for driving the active matrix bistable LCD; and

applying the drive signals to the active matrix bistable LCD.

6. The method as recited in

claim 5

, wherein the active matrix bistable LCD comprises a Cholesteric LCD.

7. The method as recited in

claim 5

, wherein the generating step is performed when the status bits for the respective one of the pixels correspond to a non-zero binary number.

8. The method as recited in

claim 5

, wherein the generating, converting, and applying steps are repeated for a corresponding pixel N times, where N is an integer established by the status bits.

9. A method for operating a graphics controller including a memory, which stores color data and status bits corresponding to a plurality of pixels, coupled to a low power color display, which includes an active matrix bistable liquid crystal display (LCD) having a plurality of cells arranged in a matrix, each cell corresponding to respective one of the pixels, via driver circuitry, the LCD receiving drive signals suitable for driving the active matrix bistable LCD from the driver circuitry responsive to voltage data;

comprising;

generating the voltage data for each respective one of the pixels based on the color data and the status bits for that pixel;

decrementing the status bits by 1 to thereby produce decremented status bits for that pixel;

overwriting the status bits for that pixel with the decremented status bits; and

repeating the generating, the decrementing, and the overwriting steps until the status bits stored in the memory for that pixel represent a zero value.

10. The method as recited in

claim 9

, wherein the LCD comprises a Cholesteric LCD.

11. The method as recited in

claim 9

, further comprising the step of:

setting the status bits to a predetermined value when the corresponding color data for a respective one of the pixels stored in the memory is replaced by new color data.

12. A method for operating a graphics controller including a memory, which stores color data and status bits corresponding to a plurality of pixels, coupled to a low power color display, which includes an active matrix bistable liquid crystal display (LCD) having a plurality of cells arranged in a matrix, each cell corresponding to respective one of the pixels, via driver circuitry, the LCD receiving drive signals suitable for driving the active matrix bistable LCD from the driver circuitry responsive to voltage data;

comprising;

generating the voltage data for each respective one of the pixels based on the color data and the status bits for each pixel having non-zero status bits;

decrementing the status bits by 1 to thereby produce decremented status bits for each pixel having the non-zero status bits;

overwriting the status bits with the decremented status bits for each pixel having the non-zero status bits; and

repeating the generating, the decrementing, and the overwriting steps until the status bits stored in the memory for all of the pixels represent a zero value.

13. The method as recited in

claim 12

, further comprising:

generating a sleep signal when all of the status bits for all of the pixels represent zero values, wherein;

the driver circuitry has on and off states, and

the driver circuitry switches from the on state to the off state responsive to the sleep signal.

14. The method as recited in

claim 12

, wherein the LCD comprises a Cholesteric LCD.

15. The method as recited in

claim 12

, further comprising the step of:

setting the status bits to a predetermined value when corresponding color data for a respective one of the pixels is stored in the memory.

16. The method as recited in

claim 12

, wherein a first value represented by the status bits corresponding to a first one of the pixels is not equal to a second value represented by the status bits corresponding to a second one of the pixels.

17. The method as recited in

claim 12

, wherein a first value represented by the status bits corresponding to a first one of the pixels is equal to a second value represented by the status bits corresponding to a second one of the pixels.

18. The method as recited in

claim 12

, wherein:

the method further comprises the step of;

examining the status bits stored in the memory, the examining step being performed prior to the generating step; and

the generating step comprises generating the voltage data for each respective one of the pixels having non-zero status bits based on the color data and the status bits for that pixel.

19. The method as recited in

claim 12

, wherein:

the method further comprises the step of;

examining the status bits stored in the memory, the examining step being performed concurrent with the generating step; and

the generating step comprises generating the voltage data for each respective one of the pixels having non-zero status bits based on the color data and the status bits for that pixel.