Display device and a method of driving the same

• US 20090256818A1
• Filed: 03/23/2009
• Published: 10/15/2009
• Est. Priority Date: 04/11/2008
• Status: Active Grant

• Current Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Takama, Daisuke, Noguchi, Koji
• Granted Patent: US 8,319,737 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 2201/121 common or background
• CPC Class Codes: G06F 1/3262 Power saving in digitizer or tablet
• CPC Class Codes: G06F 1/3265 Power saving in display device
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A display device including: a plurality of pixels; pixel electrodes; n (n≧2) counter electrodes; a display functional layer; a write drive scanning portion; detection electrodes; an alternate current drive scanning portion; and a detecting portion.

Claims

1. A display device, comprising:

a plurality of pixels disposed in a matrix;

pixel electrodes provided so as to correspond to said plurality of pixels, respectively;

n (n≧

2) counter electrodes which are disposed separately from one another in a scanning direction as one disposition direction of said plurality of pixels so as to face said pixel electrodes, respectively, and which extend in the other direction intersecting perpendicularly the scanning direction;

a display functional layer having a function of displaying an image in accordance with voltages applied across said pixel electrodes and said n counter electrodes facing each other, respectively;

a write drive scanning portion for repetitively carrying out an operation for writing signal voltages for display to a predetermined number of pixel electrodes disposed in the other direction, and a shifting operation for successively switching the predetermined number of pixel electrodes as objects of write of the signal voltages for display in the scanning direction;

detection electrodes having respective electrostatic capacitances between said counter electrodes and said n detection electrodes;

an alternate current drive scanning portion for alternate current driving s (n>

s≧

1) counter electrodes of said n counter electrodes, and shifting the s counter electrodes along with the shifting operation carried out by said drive scanning portion; and

a detecting portion for detecting a change in voltage for the alternate current drive caused in each of said detection electrodes due to an influence of an external capacitance.

2. The display device according to claim 1, wherein said alternate current drive scanning portion shifts the s counter electrodes so as to include the counter electrodes facing a predetermined number of pixel electrodes as objects of update of write of the signal voltages for display.

3. The display device according to claim 1, wherein said alternate current drive scanning portion selects the two or more s counter electrodes from said n counter electrodes, and alternate current drives the two or more s counter electrodes thus selected.

4. The display device according to claim 3, wherein said alternate current drive scanning portion repetitively carries out the alternate current driving operation while shifting the objects of selection of said counter electrodes in the scanning direction, thereby shifting the s counter electrodes so that the one or more common counter electrodes are included in the objects of selection in the continuous two alternate current driving operations while the alternate current driving operation is repetitively carried out.

5. The display device according to claim 1, wherein an interval of said counter electrodes is an integral multiple of the pixel pitch.

6. The display device according to claim 1, wherein said plurality of pixels include switches connected to one another through a plurality of scanning lines and a plurality of signal lines, each of said switches serving to write the signal voltage for display from the corresponding one of said plurality of signal lines in accordance with an applied voltage to the corresponding one of said plurality of scanning lines;

and

said write drive scanning portion writes the signal voltages for display from the corresponding ones of said plurality of signal lines to the predetermined number of pixel electrodes by turning ON the corresponding ones of said switches, and successively switches the predetermined number of pixel electrodes as the objects of update of write of the signal voltages for display in the scanning direction in accordance with the applied voltages to the corresponding ones of said plurality of scanning lines.

7. The display device according to claim 1, wherein said n counter electrodes are disposed at equal intervals in the scanning direction by the same number as that of pixels;

and

said alternate current drive scanning portion shifts a combination of the counter electrodes to be alternate current driven by using a pitch at which the counter electrodes are disposed in the scanning direction as a unit.

8. The display device according to claim 1, wherein said n counter electrodes are disposed at equal intervals in the scanning direction at a rate of one counter electrode per two or more pixels;

and

said alternate current drive scanning portion, when repetitively carrying out the alternate current driving operation, shifts a combination of the counter electrodes selected by using a pitch at which the counter electrodes are disposed in the scanning direction as a unit.

9. The display device according to claim 2, wherein said n counter electrodes are disposed at an interval double or more a pitch which the disposition of said pixels has in the scanning direction;

and

said write drive scanning portion and said alternate current drive scanning portion, when the predetermined number of pixel electrodes is set as one write unit, carry out an operation for writing the signal voltages for display every write unit in the two or more write units facing the counter electrodes being alternate current driven, and, after completion of the writing operation for the two or more write units, switch the objects of the alternate current drive over to the adjacent other counter electrodes, thereby carrying out the operation for writing the signal voltages for display every write unit in the other two or more write units facing the other counter electrodes.

10. The display device according to claim 1, wherein the plurality of detection electrodes are disposed separately from one another in the other direction intersecting perpendicularly the scanning direction;

and

said detecting portion includes a plurality of voltage detector circuits for detecting changes in voltages for the alternate current drive caused by influences of external capacitances, respectively.

11. A method of driving a display device, comprising the steps of:

controlling voltages applied across a plurality of pixel electrodes provided so as to correspond to pixels, disposed in a matrix, respectively, and n (n >

2) counter electrodes disposed separately from one another in a scanning direction as one disposition direction of said plurality of pixel electrodes so as to face said plurality of pixel electrodes, respectively, thereby expressing gradations of an image; and

detecting changes in outputs, caused by influences of external capacitances, from detection electrodes having electrostatic capacitors formed between the n counter electrodes and said detection electrodes, respectively;

the first step comprising the steps of

repetitively carrying out an operation for writing signal voltages for display to a predetermined number of pixel electrodes disposed in the other direction intersecting perpendicularly the scanning direction, and shifting operation for successively switching the predetermined number of pixel electrodes as objects of write in the scanning direction; and

alternate current driving s (n>

s≧

1) counter electrodes of said n counter electrodes, and shifting the s counter electrodes in the scanning direction along with the shifting operation;

wherein in the second step, the changes in outputs based on the alternate current drive for said counter electrodes are detected.

12. The method of driving a display device according to claim 11, wherein in the alternate current driving step in the first step, the s counter electrodes are shifted so as to include the counter electrodes facing a predetermined number of pixel electrodes as objects of update of write of the signal voltages for display.

13. The method of driving a display device according to claim 11, wherein in the write drive step in the first step, the continuous two or more s counter electrodes are selected from said n counter electrodes and are alternate current driven, the alternate current driving operation is repetitively carried out while the objects of selection of the counter electrodes are shifted in the scanning direction, and the shifting operation is carried out so that the common one or more counter electrodes are included in the objects of selection while the alternate current driving operation is repetitively carried out.

14. The method of driving a display device according to claim 11, wherein in the write drive step and the alternate current driving step in the first step, in a case where said n counter electrodes have a pitch double or more a pitch which a disposition of said pixel electrodes has in the scanning direction, when the predetermined number of pixel electrodes is set as one write unit, in two or more write units facing the counter electrodes being alternate current driven, the writing operation is carried out every write unit;

after completion of the writing operation for the two or more write units, the objects of the alternate current drive are switched over to adjacent other counter electrodes; and

the writing operation is carried out every write unit in the other two or more write units facing the adjacent other counter electrodes.

15. The method of driving a display device according to claim 11, wherein in the first step, in both the shifting operation for switching the objects of write, and the shifting operation for shifting the s counter electrodes as the objects of the alternate current drive, shifting from one side to the other side in the scanning direction is repetitively, cyclically carried out multiple times in the same direction.