Electrostatic video display drive circuitry and displays incorporating same

• US 6,057,814 A
• Filed: 04/06/1998
• Issued: 05/02/2000
• Est. Priority Date: 05/24/1993
• Status: Expired due to Term

• Current Assignee: NEW Visual Media Group LLC
• Original Assignee: Display Science Incorporated
• Inventors: Kalt, Charles G.
• Primary Examiner(s): Lao, Lun-Yi
• Application Number:
  US09/055,575
• Time in Patent Office: 757 Days
• Field of Search: 345/31, 345/85, 345/58, 345/84, 345/87, 345/94, 345/95, 345/96, 345/208-210, 361/280-281, 359/227, 359/230, 340/825.79, 340/825.71, 313/459, 313/511
• US Class Current: 345/58
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G09F 13/0472 Traffic signs
• CPC Class Codes: G09F 9/372 the positions of the elements being controlled by the application of an electric field
• CPC Class Codes: G09G 2300/0473 Use of light emitting or modulating elements having two or more stable states when no power is applied
• CPC Class Codes: G09G 2300/06 Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• CPC Class Codes: G09G 2320/0209 Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display
• CPC Class Codes: G09G 3/3433 using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices using liquid crystal devices G09G3/36; using electrochromic devices G09G3/38
• CPC Class Codes: H01G 5/04 using variation of effective area of electrode
• CPC Class Codes: H04N 9/30 using solid-state colour display devices

Abstract

Disclosed are cross-talk resistant drive circuitry for electrostatic video displays and flexible, foldable and shaped embodiments of such displays including books, fanfolds and scrolls employing flexible polymer film construction. Transitorless drive circuitry uses row and column dumping capacitors to charge electrostatic pixels in a traveling group to avoid simultaneously charging row-adjacent pixels. Also, individual pixels can be shielded each with their own Faraday cage to control charge leakage from the pixel. The pixels'"'"' have spiral rollout shutters whose time parameters can be controlled by the use of suitable bleed resistors. Low-cost film technology manufacturing methods are also described.

Claims

1. An electrostatic video display comprising a raster of rows of capacitively driven light-modulating pixels having distinct logical pixel addresses, and drive circuitry to provide charging pulses to specified pixels according to an intended display image, the drive circuitry providing an image refresh cycle and generating a traveling scan in which a pixel-charging activation pulse is applied to all specified ones of a horizontally contiguous pixel group, wherein the pixel group moves progressively from row to row across the raster to visit every pixel address during each refresh cycle, the number of pixels in the group being less than the number of pixels in a row so that specified row-adjacent pixels receive charging pulses at different times whereby cross-talk is inhibited.

2. A display according to claim 1 having a row dumping capacitor connected to each row of the raster to receive charging pulses form the drive circuitry and discharge to specified pixels in the row.

3. A display according to claim 1 comprising a bleed resistor for each said row of the raster wherein each pixel comprises a movable electrode and a fixed electrode and wherein each movable electrode is connected to the drive circuitry through a respective one of the bleed resistors to delay bleed-off of charge from the pixel.

4. A display according to claim 1 comprising a radio frequency choke for each pixel row to inhibit drive pulses from traveling in an unintended row.

5. A display according to claim 1 wherein each row of pixels is supplied with a biasing direct current voltage to a value below a pixel activation threshold.

6. A display according to claim 1 wherein the drive circuitry includes a power source and, for each row of pixels, a clock switch to connect the row to the power source.

7. A display according to claim 6 having a row dumping capacitor connected to each row of the raster to receive charging pulses form the drive circuitry and discharge to specified pixels in the row and a radio frequency choke for each pixel row to inhibit drive pulses from traveling in an unintended row wherein each row of pixels is supplied with a biasing d. c. voltage to a value below a pixel activation threshold, wherein each pixel comprises a movable electrode and a fixed electrode and wherein each movable electrode is connected to the drive circuitry through a bleed resistor to delay bleed-off of charge from the pixel.

8. A display according to claim 1 wherein each pixel comprises a movable electrode and a fixed electrode, the movable electrodes of each row of pixels being interconnected, wherein the fixed electrodes are connected in columns extending transversely of the pixel row, and wherein the drive circuitry further includes a column dumping capacitor for each column of pixels.

9. A display according to claim 1 wherein the drive circuitry includes a power source and, for each column of pixels, a clock switch to connect the column to the power source.

10. A display according to claim 9 wherein the drive circuitry comprises a drain resistor for each column of pixels connected in parallel across the column dumping capacitor to leak charge across the dumping capacitor and drain static build up.

11. A display according to claim 10 wherein the drive circuitry includes:

a) a power source and, for each row of pixels, a clock switch to connect the row to the power source;

b) a row dumping capacitor connected to each row of the raster to receive charging pulses form the drive circuitry and discharge to specified pixels in the row; and

c) and a radio frequency choke for each pixel row to inhibit drive pulses form traveling in an unintended row;

wherein each row of pixels is supplied with a biasing d. c. voltage to a value below a pixel activation threshold, wherein each pixel comprises a movable electrode and a fixed electrode and wherein each movable electrode is connected to the drive circuitry through a bleed resistor to delay bleed-off of charge from the pixel.

12. A display according to claim 1 wherein each pixel, or every alternate pixel, in the display raster is shielded by a Faraday cage to control leakage of charge from the pixel.

13. A display according to claim 1 wherein the display raster is enclosed in a Faraday cage to shield the display from electrostatic interference.

14. A display according to claim 13 configured as a thin, flat panel computer, information appliance, television or indicator display.

15. A display according to claim 1 wherein each pixel comprises a movable electrode and a fixed electrode, the movable electrodes of each row of pixels are interconnected and the fixed electrode are connected in columns extending transversely of the pixel rows, the drive circuitry further comprising:

a) a row dumping capacitor connected to each row of the raster to receive charging pulses from the drive circuitry and discharge to specified pixels in the row;

b) a bleed resistor for each said row of the raster, each movable electrode being connected to the drive circuitry through a respective one of the bleed resistors to delay bleed-off of charge from the pixel;

c) a radio frequency choke for each pixel row to inhibit drive pulses from traveling in an unintended row;

d) a power source supplying each row of pixels with a biasing d. c. voltage at a value below a pixel activation threshold value;

e) a clock switch for each row of pixels to connect the row to the power source;

f) a radio frequency choke for each pixel row to inhibit drive pulses from traveling in an unintended row;

g) a column dumping capacitor for each column of pixels;

h) a clock switch for each column of pixels to connect the column to the power source; and

i) a drain resistor for each column of pixels connected in parallel across the column dumping capacitor to leak charge across the dumping capacitor and drain static build up.

16. A display according to claim 15 comprising a housing for the display, the housing providing a Faraday cage enclosing the display and shielding the display from electrostatic interference.