Display, touch detection unit, driving method, and electronic unit

• US 9,323,374 B2
• Filed: 09/21/2012
• Issued: 04/26/2016
• Est. Priority Date: 09/29/2011
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Japan Display Incorporated
• Inventors: Noguchi, Koji, Kida, Yoshitoshi, Mizuhashi, Hiroshi, Azumi, Kohei
• Primary Examiner(s): Sitta, Grant
• Assistant Examiner(s): Bogale, Amen
• Application Number:
  US13/624,297
• Publication Number:
  US 20130082977A1
• Time in Patent Office: 1,313 Days
• US Class Current: 1/1
• 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: 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 elements; drive electrodes; touch detection electrodes each forming an electrostatic capacitance with corresponding one of the drive electrodes; and a drive section applying an AC drive signal to the drive electrodes during each of a plurality of touch detection periods, the AC drive signal involving multiple transition to generate one or more transition timing pairs. The AC drive signal includes at least a first transition timing pair and a second transition timing pair over the plurality of touch detection periods. The first transition timing pair has a first transition interval, and the second transition timing pair has a second transition interval different from the first transition interval.

Claims

1. A display comprising:

display elements;

drive electrodes;

touch detection electrodes each forming an electrostatic capacitance with a corresponding one of the drive electrodes;

a drive section that applies an AC drive signal to the drive electrodes during each of a plurality of touch detection periods, the AC drive signal involving multiple transitions to generate one or more transition timing pairs; and

a detection section that samples respective detected signals output from each of the touch detection electrodes at timings before and after each transition of the AC drive signal and that performs touch detection using a sum of variations of a result of the sampling in each transition,

wherein,

(a) the AC drive signal includes, over the plurality of the touch detection periods, at least (1) a first transition timing pair that has a first transition interval and that includes a first pulse rise transition interval, then a first pulse fall transition; and

(2) a second transition timing pair that has a second transition interval different from the first transition interval and that includes a second pulse rise transition, the second transition interval, then a second pulse fall transition,

(b) the sum of variations is determined by adding (1) a first variation based on an absolute value of the subtraction of a voltage value of the detected signal at a first timing from a voltage value of the detected signal at a second timing, the first timing being immediately before the first pulse rise transition and the second timing being immediately after the first pulse rise transition;

(2) a second variation based on an absolute value of the subtraction a voltage value of a detected signal at a third timing from a voltage value of a detected signal at a fourth timing, the third timing being immediately before the first pulse fall transition and the fourth timing being immediately after the first pulse fall transition;

(3) a third variation based on an absolute value of the subtraction of a voltage value of a detected signal at a fifth timing from a voltage value of a detected signal at a sixth timing, the fifth timing being immediately before the second pulse rise transition and the sixth timing immediately after the second pulse rise transition; and

(4) a fourth variation based on an absolute value of the subtraction of a voltage value of a detected signal at a seventh timing from a voltage value of a detected signal at an eighth timing, the seventh timing being immediately before the second pulse fall transition and the eighth timing being immediately after the second pulse fall transition, and

(c) noise signals that have different frequencies are offset by operation of the detection section.

2. The display according to claim 1, wherein the first transition timing pair exists in a touch detection period different from a touch detection period in which the second transition timing pair exists.

3. The display according to claim 1, wherein an interval of the plurality of touch detection periods is varied.

4. The display according to claim 1, wherein the drive section applies the AC drive signal to a predetermined number of the drive electrodes.

5. The display according to claim 4, wherein the drive section applies the AC drive signal to the same drive electrodes over a predetermined number of touch detection periods.

6. The display according to claim 5, wherein each transition timing of the AC drive signal in one of the predetermined number of touch detection periods is different from each transition timing in one of the remaining of the predetermined number of touch detection periods.

7. The display according to claim 1, wherein a touch detection period is provided for each horizontal period of display operation.

8. The display according to claim 1, wherein the display element includes:

a liquid crystal layer, and

a pixel electrode formed between the liquid crystal layer and the drive electrode, or arranged to face the liquid crystal layer with the drive electrode in between.

9. The display according to claim 8, wherein the drive section applies a display drive signal to the drive electrodes in periods other than the touch detection periods.

10. The display according to claim 1, wherein the display element includes:

a liquid crystal layer, and

a pixel electrode arranged to face the drive electrodes with the liquid crystal layer in between.

11. The display according to claim 1, wherein a pulse width and a pulse interval of the AC drive signal in one of the touch detection periods are different from a pulse width and a pulse interval in one of the remaining touch detection periods.

12. The display of claim 11, wherein the at least two AC transition periods occur in two different horizontal scan periods.

13. The display according to claim 1, wherein the detection section is configured to offset a first noise signal of the noise signals which has a period that is the same as one of the first transition interval and the second transition interval.

14. The display according to claim 13, wherein the detection section is configured to offset a second noise signal of the noise signals which has a frequency integral multiple of the frequency of the first noise signal.

15. The display of claim 1, wherein at least two AC transition periods occur during a detection period during a same horizontal scan period.

16. A touch detection unit comprising:

drive electrodes;

touch detection electrodes each forming an electrostatic capacitance with a corresponding one of the drive electrodes;

a drive section that applies an AC drive signal to the drive electrodes during each of a plurality of touch detection periods, the AC drive signal involving multiple transition to generate one or more transition timing pairs; and

a detection section that samples respective detected signals output from each of the touch detection electrodes at timings before and after each transition of the AC drive signal and that performs touch detection using a sum of variations of a result of the sampling in each transition,

wherein,

(a) the AC drive signal includes, over the plurality of the touch detection periods, at least (1) a first transition timing pair that has a first transition interval and that includes a first pulse rise transition, the first transition interval, then a first pulse fall transition; and

(2) a second transition timing pair that has a second transition interval different from the first transition interval and that includes a second pulse rise transition, the second transition interval, then a second pulse fall transition,

(b) the sum of variations is determined by adding (1) a first variation based on an absolute value of the subtraction of a voltage value of the detected signal at a first timing from a voltage value of the detected signal at a second timing, the first timing being immediately before the first pulse rise transition and the second timing being immediately after the first pulse rise transition;

(2) a second variation based on an absolute value of the subtraction a voltage value of a detected signal at a third timing from a voltage value of a detected signal at a fourth timing, the third timing being immediately before the first pulse fall transition and the fourth timing being immediately after the first pulse fall transition;

(3) a third variation based on an absolute value of the subtraction of a voltage value of a detected signal at a fifth timing from a voltage value of a detected signal at a sixth timing, the fifth timing being immediately before the second pulse rise transition and the sixth timing immediately after the second pulse rise transition; and

(4) a fourth variation based on an absolute value of the subtraction of a voltage value of a detected signal at a seventh timing from a voltage value of a detected signal at an eighth timing, the seventh timing being immediately before the second pulse fall transition and the eighth timing being immediately after the second pulse fall transition, and

(c) noise signals that have different frequencies are offset by operation of the detection section.

17. A driving method comprising:

generating an AC drive signal that involves multiple transition to generate one or more transition timing pairs;

applying the AC drive signal to drive electrodes during each of a plurality of touch detection periods, the drive electrode forming an electrostatic capacitance with touch detection electrodes;

sampling a detected signal output from each of the touch detection electrodes at timings before and after each transition of the AC drive signal; and

determining a sum of variations of a result of the sampling in each transition,

wherein,

(a) the AC drive signal includes, over the plurality of touch detection periods, at least (1) a first transition timing pair that has a first transition interval and that includes a first pulse rise transition, the first transition interval, then a first pulse fall transition; and

(2) a second transition timing pair that has a second transition interval different from the first transition interval and that includes a second pulse rise transition, the second transition interval, then a second pulse fall transition,

(b) the sum of variations is determined by adding (1) a first variation based on an absolute value of the subtraction of a voltage value of the detected signal at a first timing from a voltage value of the detected signal at a second timing, the first timing being immediately before the first pulse rise transition and the second timing being immediately after the first pulse rise transition;

(2) a second variation based on an absolute value of the subtraction a voltage value of a detected signal at a third timing from a voltage value of a detected signal at a fourth timing, the third timing being immediately before the first pulse fall transition and the fourth timing being immediately after the first pulse fall transition;

(3) a third variation based on an absolute value of the subtraction of a voltage value of a detected signal at a fifth timing from a voltage value of a detected signal at a sixth timing, the fifth timing being immediately before the second pulse rise transition and the sixth timing immediately after the second pulse rise transition; and

(4) a fourth variation based on an absolute value of the subtraction of a voltage value of a detected signal at a seventh timing from a voltage value of a detected signal at an eighth timing, the seventh timing being immediately before the second pulse fall transition and the eighth timing being immediately after the second pulse fall transition, and

(c) noise signals that have different frequencies are offset by operation of the detection section.

18. An electronic unit including a display and a control section controlling operation using the display, the display comprising:

display elements;

drive electrodes;

touch detection electrodes each forming an electrostatic capacitance with corresponding one of the drive electrodes;

a drive section that applies an AC drive signal to the drive electrodes during each of a plurality of touch detection periods, the AC drive signal involving multiple transitions to generate one or more transition timing pairs; and

a detection section that samples respective detected signals output from each of the touch detection electrodes at timings before and after each transition of the AC drive signal and that performs touch detection using a sum of variations of a result of the sampling in each transition,

wherein,

(a) the AC drive signal includes, over the plurality of the touch detection periods, at least (1) a first transition timing pair that has a first transition interval and that includes a first pulse rise transition, the first transition interval, then a first pulse fall transition; and

(2) a second transition timing pair that has a second transition interval different from the first transition interval and that includes a second pulse rise transition, the second transition interval, then a second pulse fall transition,

(b) the sum of variations is determined by adding (1) a first variation based on an absolute value of the subtraction of a voltage value of the detected signal at a first timing from a voltage value of the detected signal at a second timing, the first timing being immediately before the first pulse rise transition and the second timing being immediately after the first pulse rise transition;

(2) a second variation based on an absolute value of the subtraction a voltage value of a detected signal at a third timing from a voltage value of a detected signal at a fourth timing, the third timing being immediately before the first pulse fall transition and the fourth timing being immediately after the first pulse fall transition;

(3) a third variation based on an absolute value of the subtraction of a voltage value of a detected signal at a fifth timing from a voltage value of a detected signal at a sixth timing, the fifth timing being immediately before the second pulse rise transition and the sixth timing immediately after the second pulse rise transition; and

(4) a fourth variation based on an absolute value of the subtraction of a voltage value of a detected signal at a seventh timing from a voltage value of a detected signal at an eighth timing, the seventh timing being immediately before the second pulse fall transition and the eighth timing being immediately after the second pulse fall transition, and

(c) noise signals that have different frequencies are offset by operation of the detection section.