TOUCH PANEL

• US 20120139868A1
• Filed: 11/29/2011
• Published: 06/07/2012
• Est. Priority Date: 12/01/2010
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: MAMBA, Norio, DOI, Koji
• Granted Patent: US 9,678,598 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• 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 capacitive touch panel includes a scanning circuit portion for inputting a drive voltage to each scanning electrode sequentially in 1st to n-th sub detection periods, a capacitance detection circuit portion for detecting a capacitance detection signal of the each detecting electrode in the 1st to n-th groups, and a control circuit portion for calculating a capacitance detection signal change amount from the capacitance detection signals of a plurality of the detecting electrodes detected by the capacitance detection circuit portion, and calculating coordinates of a touch position based on the capacitance detection signal change amounts. The control circuit portion determines, in consecutive sub detection periods, the capacitance detection signal change amount of the each detecting electrode in two groups from which the capacitance detection signals are detected in the consecutive sub detection periods, based on the capacitance detection signals consecutively detected from at least one same detecting electrode.

Claims

1. A capacitive touch panel, comprising:

a plurality of scanning electrodes arranged in a first direction;

a plurality of detecting electrodes arranged in a second direction crossing the first direction;

a scanning circuit portion for dividing one detection period, in which a drive voltage is input to one scanning electrode of the plurality of scanning electrodes, into n sub detection periods, where n≧

2, and inputting the drive voltage sequentially to the one scanning electrode in the sub detection periods 1 to n;

a capacitance detection circuit portion which detects a capacitance detection signal of each detecting electrode in a group of groups 1 to n, into which are divided the plurality of detecting electrodes so that at least one same detecting electrode is included in adjacent groups in the groups 1 to n, at the corresponding sub detection periods in the sub detection periods 1 to n; and

a control circuit portion for calculating a capacitance detection signal change amount from the capacitance detection signal detected by the capacitance detection circuit portion, and calculating coordinates of a touch position based on the calculated capacitance detection signal change amount,

wherein the control circuit portion determines, in consecutive sub detection periods, the capacitance detection signal change amount of the each detecting electrode in two groups from which the capacitance detection signals are detected in the consecutive sub detection periods, based on the capacitance detection signals consecutively detected from the at least one same detecting electrode.

2. The capacitive touch panel according to claim 1,

wherein, when the consecutive sub detection periods are a k-th sub detection period, where 1≦

k≦

n−

1, and a (k+1)th sub detection period, the scanning circuit portion inputs the drive voltage to each scanning electrode in the k-th sub detection period and the (k+1)th sub detection period,

wherein the capacitance detection circuit portion receives an input of a signal from each detecting electrode in a k-th group in the k-th sub detection period to detect the capacitance detection signal of the each detecting electrode in the k-th group, and receives an input of a signal from each detecting electrode in a (k+1)th group in the (k+1)th sub detection period to detect the capacitance detection signal of the each detecting electrode in the (k+1)th group, and

wherein the control circuit portion comprises;

k-th common noise amount calculating means for calculating a common noise amount of the k-th group from the capacitance detection signal of the each detecting electrode in the k-th group detected by the capacitance detection circuit portion;

k-th noise removing means for calculating the capacitance detection signal after noise removal of the each detecting electrode in the k-th group from the capacitance detection signal of the each detecting electrode in the k-th group detected by the capacitance detection circuit portion by using the common noise amount of the k-th group calculated by the k-th common noise amount calculating means;

k-th change amount calculating means for calculating the capacitance detection signal change amount of the each detecting electrode in the k-th group from the capacitance detection signal after the noise removal of the each detecting electrode in the k-th group calculated by the k-th noise removing means;

(k+1)th common noise amount calculating means for calculating a common noise amount of the (k+1)th group from the capacitance detection signal of the each detecting electrode in the (k+1)th group detected by the capacitance detection circuit portion;

(k+1)th noise removing means for calculating the capacitance detection signal after noise removal of the each detecting electrode in the (k+1)th group from the capacitance detection signal of the each detecting electrode in the (k+1)th group detected by the capacitance detection circuit portion by using the common noise amount of the (k+1)th group calculated by the (k+1)th common noise amount calculating means;

(k+1)th change amount calculating means for calculating the capacitance detection signal change amount of the each detecting electrode in the (k+1)th group from the capacitance detection signal after the noise removal of the each detecting electrode in the (k+1)th group calculated by the (k+1)th noise removing means; and

change amount determining means for comparing the capacitance detection signal change amount of the at least one same detecting electrode calculated by the k-th change amount calculating means and the capacitance detection signal change amount of the at least one same detecting electrode calculated by the (k+1)th change amount calculating means, and determining the capacitance detection signal change amount of the each detecting electrode in the k-th group and the (k+1)th group based on a result of the comparison.

3. The capacitive touch panel according to claim 2,

wherein the capacitance detection signal change amount of the each detecting electrode in the k-th group is calculated with the capacitance detection signal, as a reference value, after the noise removal of the each detecting electrode in the k-th group while the capacitive touch panel is not touched, and

wherein the capacitance detection signal change amount of the each detecting electrode in the (k+1)th group is calculated with the capacitance detection signal, as a reference value, after the noise removal of the each detecting electrode in the (k+1)th group while the capacitive touch panel is not touched.

4. The capacitive touch panel according to claim 2,

wherein the common noise amount of the k-th group is selected either one of a minimum value, an average value, and an intermediate value of the capacitance detection signal of the each detecting electrode in the k-th group, and

wherein the common noise amount of the (k+1)th group is selected either one of a minimum value, an average value, and an intermediate value of the capacitance detection signal of the each detecting electrode in the (k+1)th group.

5. The capacitive touch panel according to any one of claims 2 to 4,

wherein the k-th noise removing means removes the common noise amount of the k-th group calculated by the k-th common noise amount calculating means from the capacitance detection signal of the each detecting electrode in the k-th group detected by the capacitance detection circuit portion to calculate the capacitance detection signal after the noise removal of the each detecting electrode in the k-th group, and

the (k+1)th noise removing means removes the common noise amount of the (k+1)th group calculated by the (k+1)th common noise amount calculating means from the capacitance detection signal of the each detecting electrode in the (k+1)th group detected by the capacitance detection circuit portion to calculate the capacitance detection signal after the noise removal of the each detecting electrode in the (k+1)th group.

6. The capacitive touch panel according to claim 2, wherein, assuming that the capacitance detection signal change amount of the at least one same detecting electrode calculated by the k-th change amount calculating means is denoted by A, the capacitance detection signal change amount of the at least one same detecting electrode calculated by the (k+1)th change amount calculating means is denoted by B, and a predetermined threshold is denoted by Th, the change amount determining means does not correct the capacitance detection signal change amount of the each detecting electrode in the k-th group and the capacitance detection signal change amount of the each detecting electrode in the (k+1)th group when |A−

B|≦

Th is satisfied, and corrects one of the capacitance detection signal change amount of the each detecting electrodes in the k-th group and the capacitance detection signal change amount of the each detecting electrode in the (k+1)th group when |A−

B|>

Th is satisfied.

7. The capacitive touch panel according to claim 6, wherein the change amount determining means does not correct the capacitance detection signal change amount of the each detecting electrode in the k-th group, discards the capacitance detection signal change amount of the at least one same detecting electrode in the (k+1)th group, and adds a value of A to the capacitance detection signal change amount of the each detecting electrode other than the at least one same detecting electrode when A>

B is satisfied, and the change amount determining means does not correct the capacitance detection signal change amount of the each detecting electrode in the (k+1)th group, discards the capacitance detection signal change amount of the at least one same detecting electrode in the k-th group, and adds a value of B to the capacitance detection signal change amount of the each detecting electrode other than the at least one same detecting electrode when A<

B is satisfied.

8. The capacitive touch panel according to claim 1,

wherein the capacitive touch panel is placed on a display panel, and

wherein the display panel includes a plurality of video lines arranged in the first direction.

9. The capacitive touch panel according to claim 1,

wherein the capacitive touch panel is placed on a display panel,

wherein the display panel includes a plurality of video lines arranged in the first direction,

wherein the display panel displays the same color across a screen in a measurement correction amount calculating period,

wherein the scanning circuit portion inputs the drive voltage to the each scanning electrode in the measurement correction amount calculating period sequentially in 1st to n-th sub detection periods,

wherein the capacitance detection circuit portion receives an input of a signal from the each detecting electrode in 1st to n-th groups in the 1st to n-th sub detection periods in the measurement correction amount calculating period to detect the capacitance detection signal of the each detecting electrode in the 1st to n-th groups, and

wherein the control circuit portion calculates a noise correction amount for each of the 1st to n-th sub detection periods of the each scanning electrode and for the each detecting electrode in the 1st to n-th groups in the measurement correction amount calculating period.

10. The capacitive touch panel according to claim 2,

wherein the capacitive touch panel is placed on a display panel,

wherein the display panel includes a plurality of video lines arranged in the first direction,

wherein the display panel displays the same color across a screen in a measurement correction amount calculating period,

wherein the scanning circuit portion inputs the drive voltage to the each scanning electrode in the measurement correction amount calculating period sequentially in 1st to n-th sub detection periods,

wherein the capacitance detection circuit portion receives an input of a signal from the each detecting electrode in 1st to n-th groups in the 1st to n-th sub detection periods in the measurement correction amount calculating period to detect the capacitance detection signal of the each detecting electrode in the 1st to n-th groups,

wherein the control circuit portion comprises:

k-th detecting electrode noise amount calculating means for calculating a noise amount at every k-th sub detection period of the each scanning electrode and for the each detecting electrode in the k-th group from the capacitance detection signal of the each detecting electrode in the k-th group detected by the capacitance detection circuit portion in the measurement correction amount calculating period;

k-th correction amount calculating means for calculating the noise correction amount at every k-th sub detection period of the each scanning electrode and for the each detecting electrode in the k-th group from the noise amount at every k-th sub detection period of the each scanning electrode and for the each detecting electrode in the k-th group calculated by the k-th detecting electrode noise amount calculating means;

(k+1)th detecting electrode noise amount calculating means for calculating a noise amount at every (k+1)th sub detection period of the each scanning electrode and for the each detecting electrode in the (k+1)th group from the capacitance detection signal of the each detecting electrode in the (k+1)th group detected by the capacitance detection circuit portion; and

(k+1)th correction amount calculating means for calculating the noise correction amount at every (k+1)th sub detection period of the each scanning electrode and for the each detecting electrode in the (k+1)th group from the noise amount at every (k+1)th sub detection period of the each scanning electrode and for the each detecting electrode in the (k+1)th group calculated by the (k+1)th detecting electrode noise amount calculating means,

wherein the k-th noise removing means calculates the capacitance detection signal after the noise removal of the each detecting electrode in the k-th group from the capacitance detection signal of the each detecting electrode in the k-th group detected by the capacitance detection circuit portion, by using the common noise amount of the k-th group and the noise correction amount at every k-th sub detection period of the each scanning electrode and for the each detecting electrode in the k-th group calculated by the k-th correction amount calculating means, and

wherein the (k+1)th common noise amount calculating means calculates the capacitance detection signal after the noise removal of the each detecting electrode in the (k+1)th group from the capacitance detection signal of the each detecting electrode in the (k+1)th group detected by the capacitance detection circuit portion, by using the common noise amount of the (k+1)th group and the noise correction amount at every the (k+1)th sub detection period of the each scanning electrodes and for the each detecting electrode in the (k+1)th group calculated by the (k+1)th correction amount calculating means.

11. The capacitive touch panel according to claim 10,

wherein the noise amount calculated at every k-th sub detection period of the each scanning electrode and for the each detecting electrode in the k-th group comprises one of a maximum value, a minimum value, and an average value of the capacitance detection signal detected from the each detecting electrode in the k-th group detected by the capacitance detection circuit portion, and

wherein the noise amount calculated at every (k+1)th sub detection period of the each scanning electrodes and for the each detecting electrode in the (k+1)th group comprises one of a maximum value, a minimum value, and an average value of the capacitance detection signal detected from the each detecting electrode in the (k+1)th group.

12. The capacitive touch panel according to claim 10,

wherein the noise correction amount calculated at every k-th sub detection period of the each scanning electrode and for the each detecting electrode in the k-th group comprises a value that is proportional to the noise amount calculated at every k-th sub detection period of the each scanning electrode and for the each detecting electrode in the k-th group, and

wherein the noise correction amount calculated at every (k+1)th sub detection period of the each scanning electrode and for the each detecting electrode in the (k+1)th group comprises a value that is proportional to the noise amount calculated at every (k+1)th sub detection period of the each scanning electrode and for the each detecting electrode in the (k+1)th group.

13. The capacitive touch panel according to claim 10,

wherein the k-th change amount calculating means removes the common noise amount of the k-th group and the noise correction amount at every k-th sub detection period of the each scanning electrode and for the each detecting electrode in the k-th group calculated by the k-th correction amount calculating means from the capacitance detection signal of the each detecting electrode in the k-th group detected by the capacitance detection circuit portion to calculate the capacitance detection signal after the noise removal of the each detecting electrode in the k-th group, and

wherein the (k+1)th change amount calculating means removes the common noise amount of the (k+1)th group and the noise correction amount at every (k+1)th sub detection period of the each scanning electrode and for the each detecting electrode in the (k+1)th group calculated by the (k+1)th correction amount calculating means from the capacitance detection signal of the each detecting electrode in the (k+1)th group detected by the capacitance detection circuit portion to calculate the capacitance detection signal after the noise removal of the each detecting electrode in the (k+1)th group.