Low power active display system

• US 6,232,937 B1
• Filed: 06/27/1997
• Issued: 05/15/2001
• Est. Priority Date: 10/31/1996
• Status: Expired due to Term

• Current Assignee: Kopin Corporation
• Original Assignee: Kopin Corporation
• Inventors: Jacobsen, Jeffrey, Fan, John C. C., Pombo, Stephen A., Zavracky, Matthew, Bumgardner, Rodney, Richard, Alan, Chern, Wen-Foo
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Marc-Coleman, Marthe Y.
• Application Number:
  US08/884,485
• Time in Patent Office: 1,418 Days
• Field of Search: 345/95, 345/96, 345/100, 345/101, 345/102, 345/87, 345/8, 349/62, 349/141
• US Class Current: 345/87
• CPC Class Codes: G02B 25/002 Magnifying glasses
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/0283 Arrangement of drivers for different directions of scanning
• CPC Class Codes: G09G 2310/063 Waveforms for resetting the whole screen at once
• 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 2320/041 Temperature compensation
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2340/0407 Resolution change, inclusive of the use of different resolutions for different screen areas
• CPC Class Codes: G09G 2340/0492 Change of orientation of the displayed image, e.g. upside-down, mirrored
• CPC Class Codes: G09G 3/001 using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: G09G 5/18 Timing circuits for raster scan displays specially adapted for television H04N ; synchronisation between the display unit and other display units, videodisc player G09G5/12
• CPC Class Codes: G09G 5/39 Control of the bit-mapped memory
• CPC Class Codes: G09G 5/391 Resolution modifying circuits, e.g. variable screen formats
• CPC Class Codes: H04M 1/0202 Portable telephone sets, e.g. cordless phones, mobile phones or bar type handsets constructional features of telephone transmitters or receivers, e.g. of speakers or microphones H04M1/03
• CPC Class Codes: H04M 1/021 : using combined folding and rotation motions combined with translation movement H04M1/0235
• CPC Class Codes: H04M 1/0214 : Foldable telephones, i.e. with body parts pivoting to an open position around an axis parallel to the plane they define in closed position combined with translation movement H04M1/0235
• CPC Class Codes: H04M 1/0247 : comprising more than two body parts
• CPC Class Codes: H04M 1/0254 : comprising one or a plurality of mechanically detachable modules
• CPC Class Codes: H04M 1/0264 : for a camera module assembly
• CPC Class Codes: H04M 2250/20 : including a rotatable camera
• CPC Class Codes: H04N 7/142 : Constructional details of the terminal equipment, e.g. arrangements of the camera and the display
• CPC Class Codes: H04N 9/3141 : Constructional details thereof details not peculiar to the presence of an electronic spatial light modulator G03B21/14

Abstract

The invention relates to a microdisplay system that utilizes a small high resolution active matrix liquid crystal display with an illumination system and a magnifying optical system to provide a hand held communication display device. The system has an alternating common voltage which allows reduced power consumption. In addition an internal heating system in the display allows the system to be used at low temperatures. The system can employ an LED illumination system and cellular communication or processor circuits within a compact housing to provide communication devices such as pagers, telephones, televisions, and hand held computer or card reader devices with a compact high resolution data and/or video display.

Claims

1. An active matrix display comprising:

an active matrix circuit having an array of transistor circuits formed in a first plane, each transistor circuit being connected to a pixel electrode in an array of pixel electrodes of at least 75,000 pixels having an active area of less than 160 mm²;

a counterelectrode panel extending in a second plane that is parallel to the first plane, such that the counterelectrode panel receives an applied voltage;

a switching circuit connected to the counterelectrode panel that switches the applied voltage to the counterelectrode;

a light transmitting material positioned over each pixel electrode such that actuation of a transistor circuit in the array alters an optical transmission property of the light transmitting material;

a light source that sequentially flashes to illuminate the optical transmitting material; and

a circuit that times actuation of the pixel electrodes to write an image, flashing of the light source to illuminate the image and switching of the applied voltage to the counterelectrode to destroy the image.

2. The active matrix display of claim 1 wherein the active matrix circuit is attached to a substrate.

3. The active matrix display of claim 2 further comprising a temperature sensor positioned between the substrate and the counterelectrode that measures a temperature of the active matrix region.

4. The active matrix display of claim 2 further comprising a heating element.

5. The active matrix display of claim 4 wherein the heating element is between the substrate and the counterelectrode.

6. The active matrix display of claim 1 further comprising a heating element having a plurality of lines connecting transistor circuits of the pixel electrodes.

7. The active matrix display of claim 1 wherein the pixel electrodes comprise polycrystalline silicon formed over a silicon-on-insulator (SOI) structure.

8. A method of driving an active matrix display comprising the following steps:

providing an active matrix circuit having an array of transistor circuits formed in a first plane, each transistor circuit, being connected to a pixel electrode in an array of pixel electrodes;

actuating of the transistor circuits in the array to alter an optical transmission property of a light transmitting material positioned over each pixel electrode;

flashing an LED light source after scanning of an image frame to illuminate the image;

switching an applied voltage across a counter electrode panel to destroy the image, the counterelectrode panel extending in a second plane that is parallel to the first plane; and

inverting image data after an image frame has been scanned onto the display the timing of the steps of flashing switching and inverting are interelated and controlled by a timing circuit.

9. The method of claim 8 further comprising the step of waiting a period after the scanning of the frame prior to the flashing of the LED backlight.

10. The method of claim 9 wherein the time period of the waiting period after the scanning of the frame is dependent for a first color to be flashed and a second color to be flashed.

11. The method of claim 9 wherein the time period of the waiting period after the scanning of the frame prior to the flash of the LED backlight is adjusted in relation to the wavelength of the light to be flashed.

12. A method of heating an active matrix display comprising the following steps:

providing an active matrix display having an array of transistor circuits formed in a first plane, each transistor circuit being connected to a pixel electrode in an array of pixel electrodes, the active matrix circuit being positioned between a substrate and a cover layer;

heating the display with a heating element having a plurality of lines connecting the transistor circuits of the pixel electrodes, and the heating element located between the substrate and the cover layer.

13. The method of claim 12 wherein the step of heating occurs prior to scanning an image frame onto the display and flashing a backlight.

14. The method claim 12 further comprising the step of sensing a temperature of the display.

15. A display control circuit comprising:

a processor for receiving image data;

an active matrix display for displaying the image data, the display having an array of at least 320×

240 pixel electrodes and a diagonal of less than 0.5 inches;

a timing control circuit connected to the processor and the display to control the circuit;

a switch adapted to select a high or low common voltage for sending to the display;

a second switch adapted to select a video or inverted video signal to be transmitted to the display;

a light source that sequentially flashes to illuminate the active matrix display; and

a timing circuit that times actuation of the pixel electrodes to write an image, flashing of the light source to illuminate the image, and switching of the applied voltage to the counterelectrode to destroy the image.

16. The display of claim 15 further comprising a temperature sensor on the display and temperature feedback line extending from the sensor to the timing control circuit.

17. The display of claim 15 further comprising a heating element.

18. An active matrix display comprising:

an active matrix circuit having an array of transistor circuits formed in a first plane, each transistor circuit being connected to a pixel electrode in an array of pixel electrodes of at least 75,000 pixels having an active area of less than 160 mm²;

a liquid crystal layer, the liquid crystal positioned over each pixel electrode;

a counterelectrode panel extending in a second plane that is parallel to the first plane, the liquid crystal layer interposed between the counterelectrode panel and the first plane, and the counterelectrode panel receives an applied voltage;

a drive circuit for setting each of the pixel electrodes to a specific voltage for altering an optical transmission property of the light crystal material;

a switching circuit connected to the counterelectrode panel that switches the applied voltage to the counterelectrode;

an LED light source that sequentially flashes to illuminate the liquid crystal display, and

a timing circuit timing driving of the pixel electrodes to a specific voltage, flashing of the light source, and switching of the applied voltage to the counterelectrode.

21. The active matrix display of claim 23 wherein the heating element is between the substrate and the counterelectrode.

19. The active matrix display of claim 21 further comprising a temperature sensor positioned between the substrate and the counterelectrode that measures a temperature of the active matrix region.

22. The active matrix display of claim 24 wherein the heating element is the plurality of lines connecting transistor circuits of the pixel electrodes.

20. The active matrix display of claim 22 further comprising a heating element.