Display system having common electrode modulation

• US 5,920,298 A
• Filed: 12/19/1996
• Issued: 07/06/1999
• Est. Priority Date: 12/19/1996
• Status: Expired due to Term

• Current Assignee: Emerson Radio Corporation (Nimble Holdings Co. Ltd.)
• Original Assignee: Colorado Microdisplay Inc.
• Inventors: McKnight, Douglas
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): Nguyen, Francis N.
• Application Number:
  US08/770,233
• Time in Patent Office: 929 Days
• Field of Search: 345/87, 345/88, 345/90, 345/94, 345/95, 345/98, 345/100, 345/151, 345/89, 345/208, 345/92, 345/147, 345/148, 445/24, 349/86, 349/78, 349/102
• US Class Current: 345/87
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0823 used to establish symmetry in driving, e.g. with polarity inversion
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/063 Waveforms for resetting the whole screen at once
• CPC Class Codes: G09G 2320/0204 Compensation of DC component across the pixels in flat panels
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• 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 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

An electro-optic display system having cover glass electrode modulation. The display system comprises an electro-optic layer disposed between first and second substrates having a single common electrode and a plurality of pixel electrodes, respectively. Voltage modulation of the common electrode is temporally related to image data acquisition by the pixel electrodes and allows data to be updated to each of the plurality of pixel electrodes simultaneously.

Claims

1. A color sequential display system comprising:

a first substrate having a first plurality of pixel electrodes for receiving a first plurality of pixel data values representing a first image to be displayed;

an electro-optic layer operatively coupled to said pixel electrodes;

a liquid crystal color filter operatively coupled to said electro-optic layer, said liquid crystal color filter having a first color state and a second color state wherein said electro-optic layer is illuminated with a first produced by said liquid crystal color filter in said first color state and said electro-optic layer is illuminated with a second color produced by said liquid crystal color filter in said second color state;

an electrode operatively coupled to said electro-optic layer, said display system displaying said first image while said liquid crystal color filter is in said first color state and then applying a first control voltage to said electrode to alter a state of said electro-optic layer such that said first image is substantially not displayed and then changing said liquid crystal color filter to said second color state and loading a second plurality of pixel data values onto said first plurality of pixel electrodes and then said display system displaying a second image represented by said second plurality of pixel data values after said electrode receives a second control voltage.

2. A color sequential display system as in claim 1 wherein said electro-optic layer comprises a liquid crystal and said electrode comprises a cover glass electrode.

3. A color sequential display system as in claim 2 wherein for at least a set of pixels of said first image, said electro-optic layer has not reached a saturated display level for said set of pixels when said first control voltage is applied to said electrode.

4. A color sequential display system as in claim 2 wherein said second image is displayed during a time when said liquid crystal filter is in said second color state.

5. A color sequential display system as in claim 2 wherein said first control voltage and said second control voltage are set such that said electrode receives an electrode voltage over time which is DC balanced.

6. A color sequential display system as in claim 2 wherein said first image and said second image are independent color subframes of a full color frame.

7. A color sequential display system as in claim 6 wherein said first control voltage drives said electro-optic layer to dark between said independent color subframes.

8. A color sequential display system as in claim 2 wherein at least one of said first control voltage and said second control voltage is approximately equal to a maximum voltage which can be applied to said first plurality of pixel electrodes.

9. A color sequential display system as in claim 7 wherein said first control voltage is applied to said electrode while loading said second plurality of pixel data values and while changing said liquid crystal color filter to said second color state.

10. A method for operating a display system, said display system comprising a first substrate having a plurality of pixel electrodes, an electro-optic layer operatively coupled to said pixel electrodes, a switchable color filter operatively coupled to said electro-optic layer, and an electrode operatively coupled to said electro-optic layer, said method comprising:

applying a first plurality of pixel data values to said plurality of pixel electrodes such that a first pixel data represented by said first plurality of pixel data values is displayed after said switchable color filter is set to a first color state wherein said electro-optic layer is illuminated with a first color produced by said switchable color filter in said first color state;

applying a first control voltage to said electrode to alter a state of said electro-optic layer after applying said first plurality of pixel data values to said plurality of pixel electrodes such that said first pixel data is substantially not displayed;

changing said switchable color filter to a second color state after applying said first control voltage;

applying a second plurality of pixel data values to said plurality of pixel electrodes after applying said first control voltage to said electrode, said second plurality of pixel data values representing a second pixel data;

displaying said second pixel data after said switchable color filter is switched to said second color state.

11. A method as in claim 10 wherein said step of displaying said second pixel data comprises:

applying a second control voltage to said electrode to alter said state of said electro-optic layer such that said second pixel data is displayed, and

wherein a first image is represented by said first pixel data and a second image is represented by said second pixel data.

12. A method as in claim 11 wherein said electro-optic layer comprises a liquid crystal and said electrode is a common cover glass electrode and said switchable color filter is a liquid crystal color filter.

13. A method as in claim 11 wherein said second plurality of pixel data values are applied to said plurality of pixel electrodes while said first control voltage is applied to said electrode.

14. A method as in claim 13 wherein said first pixel data and said second pixel data are independent color subframes of a full color frame.

15. A method as in claim 14 wherein said first control voltage drives said electro-optic layer to dark between said independent color subframes.

16. A method as in claim 15 wherein said first control voltage and said second control voltage are set such that said electrode receives an electrode voltage over time which is DC balanced.