Display system having electrode modulation to alter a state of an electro-optic layer

• US 6,329,971 B2
• Filed: 04/04/2000
• Issued: 12/11/2001
• Est. Priority Date: 12/19/1996
• Status: Expired due to Term

• Current Assignee: Emerson Radio Corporation (Nimble Holdings Co. Ltd.)
• Original Assignee: Zight Corporation (Three-Five Systems, Inc.)
• Inventors: McKnight, Douglas
• Primary Examiner(s): Brier, Jeffery
• Assistant Examiner(s): Blackman, Anthony J.
• Application Number:
  US09/542,432
• Publication Number:
  US 20010026259A1
• Time in Patent Office: 616 Days
• Field of Search: 345/95, 345/94, 345/208, 345/210
• US Class Current: 345/95
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0823 used to establish symmetry in driving, e.g. with polarity inversion
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• 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 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• 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 3/3659 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 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

Methods and systems for operating a display system. An example of the display system includes a first substrate having a plurality of pixel electrodes, an electro-optic layer operatively coupled to the pixel electrodes and an electrode operatively coupled to said electro-optic layer. In one example of a method of the invention, a first plurality of pixel data values is applied to the plurality of pixel electrodes. A first control voltage is applied to the electrode to alter a state of the electro-optic layer such that the first pixel data represented by the first plurality of pixel data values is substantially not displayed. A second plurality of pixel data values, representing a second pixel data, is applied to the plurality of pixel electrodes, and a second control voltage is applied to the electrode to alter the state of the electro-optic layer such that the second pixel data is displayed. In an example of a first aspect of the invention, a voltage difference between the first control voltage and the second control voltage is reduced to reduce capacitive shifting of the second plurality of pixel data values on the plurality of pixel electrodes. In an example of a second aspect of the invention, at least one of the first control voltage, the second control voltage and a pixel data value of the second plurality of pixel data values is determined by an illumination color used in displaying said second pixel data. In an example of a third aspect of the invention, the electrode receives a composite signal over time, and a first parameter of at least one of the first control voltage and the second control voltage is selected to provide an offset, for a portion of the composite signal, from a DC balanced signal over time with respect to a particular voltage.

Claims

1. 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 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;

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

applying a second plurality of pixel data values to said plurality of pixel electrodes, said second plurality of pixel data values representing a second pixel data which is displayed next in sequence after said first pixel data is substantially not displayed;

after applying said second plurality of pixel data values, applying a second control voltage to said electrode, after applying said first control voltage, to alter said state of said electro-optic layer such that said second pixel data is displayed, and wherein said first control voltage is one of a high extreme and a low extreme and wherein said second control voltage is one of a high view extreme or a low view extreme and wherein when a maximum voltage across said electro-optic layer is desired for a frame or a subframe, a pixel electrode voltage, corresponding to one of said second plurality of pixel data values, is one of a high pixel extreme voltage or a low pixel extreme voltage, and wherein a voltage signal applied to said electrode in transitioning from said first control voltage to said second control voltage does not cross a voltage level defined substantially by a midpoint between said high pixel extreme voltage and said low pixel extreme voltage.

2. A method as in claim 1 wherein said second plurality of pixel data values is determined relative to said second control voltage in order to reduce capacitive shifting and wherein said second control voltage is applied next in sequence after applying said first control voltage.

3. A method as claim 2 wherein, when said maximum voltage across said electro optic layer is desired during display of said second pixel data, said pixel electrode voltage is substantially at said high pixel extreme voltage when said second control voltage is substantially at said low view extreme and said first control voltage, for said frame or said subframe, was previously at said low extreme.

4. A method as in claim 1 wherein, when a minimum voltage across said electro-optic layer is desired during display of said second pixel data, said pixel electrode voltage is substantially at said high pixel extreme voltage when said second control voltage is substantially at said high view extreme and said first control voltage, for said frame or said subframe, was previously at said high extreme.

5. A method as in claim 1 wherein, when said minimum voltage across said electro-optic layer is desired during display of said second pixel data, said pixel electrode voltage is substantially at said low pixel extreme voltage when said second control voltage is substantially at said low view extreme and said first control voltage, for said frame or said subframe, was previously at said low extreme.

6. A method as in claim 1 wherein a first image is represented by said first pixel data and a second image is represented by said second pixel data and wherein said first image comprises a first color subframe for a first color and said second image comprises a second color subframe for a second color.

7. A method as in claim 6 wherein at least one of said low extreme and said high extreme of said first control voltage is determined by the color of said second color.

8. A method as in claim 6 wherein at least one of said high view extreme and said low view extreme of said second control voltage is determined by the color of said second color.

9. A method as in claim 6 wherein at least one of said high pixel extreme voltage and said low pixel extreme voltage is determined in part by the color of said second color.

10. A method as in claim 1 wherein said applying of said first control voltage and said applying of said second plurality of pixel data values overlap at least partially in time.

11. A method as in claim 10 wherein said electrode is a cover glass electrode.

12. A method as in claim 11 wherein said cover glass electrode receives a DC balanced signal over time with respect to a voltage level.

13. A method as in claim 1 wherein said display system is segmented such that said electrode covers only a portion of a display surface of said display system.

14. A method as in claim 11 wherein said display system comprises a liquid crystal disposed on a semiconductor substrate and said plurality of pixel electrodes are disposed on said semiconductor substrate.

15. A method as in claim 1 wherein said electro-optic layer comprises a liquid crystal material and wherein said liquid crystal has at least a first light altering state and a second light altering state and wherein said first control voltage sets said liquid crystal in said first light altering state such that light substantially cannot pass through said display system and wherein said second control voltage allows said liquid crystal to be set in said second light altering state such that light is capable of passing through said display system and wherein said applying a first control voltage further comprises applying a third control voltage after said first control voltage and before said applying said second control voltage, wherein said third control voltage substantially holds said liquid crystal in nearly said first light altering state and said first control voltage rapidly places said liquid crystal in substantially said first light altering state.

16. A method as in claim 15 wherein said applying of said third control voltage and said applying of said second plurality of pixel data values overlap at least partially in time.

17. A method as in claim 16 wherein said applying of said third control voltage and said applying of said second plurality of pixel data values occur substantially contemporaneously.

18. A method as in claim 1 wherein after applying said second control voltage, said electro-optic layer relaxes to a plurality of gray scale or color levels corresponding to said second plurality of pixel data values.

19. A method as in claim 18 wherein for at least a set of pixels of said first pixel data, said electro-optic layer has not reached a steady state display level specified by said first pixel data when said first control voltage is applied.

20. A method as in claim 1 further comprising illuminating said display system with at least one pulse of illumination which does not provide continuous illumination during the time that said second pixel data is available for display.

21. A method as in claim 20 wherein said second pixel data is available for display while said second control voltage is applied.

22. A method as in claim 16 further comprising applying a first reference voltage to at least one of said pixel electrodes and wherein said applying of said first reference voltage and said applying of a first control voltage overlap at least partially in time.