Touch sensor, display and electronic unit

• US 8,633,905 B2
• Filed: 05/28/2010
• Issued: 01/21/2014
• Est. Priority Date: 06/29/2009
• Status: Active Grant

• Current Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Original Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Inventors: Harada, Tsutomu, Noguchi, Kouji, Kida, Yoshitoshi, Ishizaki, Koji, Nakanishi, Takayuki, Takeuchi, Takeya
• Primary Examiner(s): Eisen, Alexander
• Assistant Examiner(s): Lee, Jr., Kenneth B
• Application Number:
  US12/790,146
• Publication Number:
  US 20100328239A1
• Time in Patent Office: 1,334 Days
• Field of Search: 345173-183
• US Class Current: 345/173
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• 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: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A display includes: display pixel electrodes; common electrodes; a display layer; a display control circuit performing image display control based on an image signal; touch detection electrodes each arranged to form a capacitance between each of the touch detection electrodes and each of the common electrodes; and a touch detection circuit detecting an external proximity object based on a detection signal obtained from the touch detection electrodes with use of a common drive voltage for display applied to the common electrodes by the display control circuit as a touch sensor drive signal. The touch detection circuit includes: an A/D (analog-digital) converter section performing sampling of a detection signal obtained from each of the touch detection electrodes at three or more different sampling frequencies to produce three or more sampling detection signals, and a detection section performing a detection operation based on the three or more sampling detection signals.

Claims

1. A display comprising:

a plurality of display pixel electrodes;

a plurality of common electrodes arranged to face the display pixel electrodes;

a display layer;

a display control circuit performing image display control based on an image signal so as to activate the display layer by applying a voltage for display between the display pixel electrodes and the common electrodes;

a plurality of touch detection electrodes facing the common electrodes or each arranged side by side with each of the common electrodes to form a capacitance between each of the touch detection electrodes and each of the common electrodes; and

a touch detection circuit detecting an external proximity object based on a detection signal obtained from the touch detection electrodes with use of a common drive voltage for display applied to the common electrodes by the display control circuit as a touch sensor drive signal,

wherein the touch detection circuit includes;

an A/D (analog-digital) converter section performing sampling of a detection signal obtained from each of the touch detection electrodes at three or more different sampling frequencies to produce three or more sampling detection signals, and

a detection section performing a detection operation based on the three or more sampling detection signals, and further wherein the detection section performs a majority rule operation with the three or more sampling detection signals, and performs a detection operation with use of one sampling detection signal obtained by the majority rule operation.

2. The display according to claim 1, wherein

each of the sampling frequencies is a frequency of N times (N is an integer of 2 or greater) as high as a fundamental frequency of the touch sensor drive signal.

3. The display according to claim 2, wherein

in each of the sampling frequencies, N is a prime number.

4. The display according to claim 2, wherein

the touch detection circuit includes a filter section allowing fundamental detection signals, contained in the respective three or more sampling detection signals and having a frequency same as a fundamental frequency of the touch sensor drive signal, to pass therethrough, and to be supplied to the detection section.

5. The display according to claim 1, wherein

the A/D converter section performs the sampling of the detection signal at a timing other than a generation timing of internal noise caused by a writing operation of an image signal by the display control circuit.

6. The display according to claim 1, wherein

a fundamental frequency of the touch sensor drive signal is lower than an external noise frequency.

7. The display according to claim 1, wherein

a fundamental frequency of the touch sensor drive signal is equal to or lower than 40 kHz.

8. The display according to claim 1, wherein

the common electrodes are a plurality of strip-shaped electrode patterns.

9. The display according to claim 8, wherein

the display control circuit drives and scans the common electrodes in such a manner that a group of electrode patterns selected from the plurality of electrode patterns are driven at a time, while such a selection of the group of electrode patterns is sequentially shifted.

10. The display according to claim 1, comprising:

a circuit substrate in which the display control circuit is formed; and

an opposed substrate arranged to face the circuit substrate,

wherein the display pixel electrodes are arranged on a side, facing the opposed substrate, of the circuit substrate,

the common electrodes are arranged on a side facing the circuit substrate of the opposed substrate, and

the display layer is sandwiched between the display pixel electrodes of the circuit substrate and the common electrodes of the opposed substrate.

11. The display according to claim 9, wherein

the display layer is a liquid crystal layer.

12. The display according to claim 1, comprising:

a circuit substrate in which the display control circuit is formed; and

an opposed substrate arranged to face the circuit substrate,

wherein the common electrodes and the display pixel electrodes are laminated in order on the circuit substrate with an insulating layer in between, and

the display layer is sandwiched between the display pixel electrodes of the circuit substrate and the opposed substrate.

13. The display according to claim 11, wherein

the display layer is a liquid crystal layer to perform liquid crystal display in a transverse electric mode.

14. A touch sensor comprising:

a plurality of touch drive electrodes;

a plurality of touch detection electrodes facing the touch drive electrodes or each arranged side by side with each of the touch drive electrodes to form a capacitance between each of the touch detection electrodes and each of the touch drive electrodes; and

a touch detection circuit detecting an external proximity object based on a detection signal obtained from the touch detection electrodes by applying a touch sensor drive signal to the touch drive electrodes,

wherein the touch detection circuit includes;

an A/D (analog-digital) converter section performing sampling of a detection signal obtained from each of the touch detection electrodes at three or more different sampling frequencies to produce three or more sampling detection signals, and, further wherein a detection section performs a majority rule operation with the three or more sampling detection signals, and performs a detection operation with use of one sampling detection signal obtained by the majority rule operation.

15. An electronic unit having a display with a touch sensor, the display comprising:

a plurality of display pixel electrodes;

a plurality of common electrodes arranged to face the display pixel electrodes;

a display layer;

a display control circuit performing image display control based on an image signal so as to activate the display layer by applying a voltage for display between the display pixel electrodes and the common electrodes;

a plurality of touch detection electrodes facing the common electrodes or each arranged side by side with each of the common electrodes to form a capacitance between each of the touch detection electrodes and each of the common electrodes; and

a touch detection circuit detecting an external proximity object based on a detection signal obtained from the touch detection electrodes with use of a common drive voltage for display applied to the common electrodes by the display control circuit as a touch sensor drive signal,

wherein the touch detection circuit includes;

an A/D (analog-digital) converter section performing sampling of a detection signal obtained from each of the touch detection electrodes at three or more different sampling frequencies to produce three or more sampling detection signals, and, further wherein a detection section performs a majority rule operation with the three or more sampling detection signals, and performs a detection operation with use of one sampling detection signal obtained by the majority rule operation.