COORDINATE DETECTING DEVICE AND COORDINATE DETECTING PROGRAM

• US 20120319994A1
• Filed: 06/19/2012
• Published: 12/20/2012
• Est. Priority Date: 06/20/2011
• Status: Active Grant

• Current Assignee: Alps Alpine Co., Ltd.
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Hatano, Naoyuki
• Granted Patent: US 8,917,257 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 2203/04112 Electrode mesh in capacitive digitiser: electrode for touch sensing is formed of a mesh of very fine, normally metallic, interconnected lines that are almost invisible to see. This provides a quite large but transparent electrode surface, without need for ITO or similar transparent conductive material
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• 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 coordinate detecting device includes a detecting unit configured to detect the capacitance of each of a plurality of electrodes arranged in a predetermined direction and an arithmetic processing unit configured to calculate the coordinates of a detection target using different calculation methods according to the state of a variation in the capacitance of the plurality of electrodes. The arithmetic processing unit calculates the coordinates of the detection target, using one of a centroid calculation method of calculating the coordinates of the centroid and a curve approximation method of calculating a peak of a curve according to a comparison value between a capacitance variation of a peak electrode and a capacitance variation of an electrode which is not adjacent to the peak electrode.

Claims

1. A coordinate detecting device comprising:

a plurality of electrodes arranged in a predetermined direction;

a detecting unit configured to detect the capacitance of each of the plurality of electrodes; and

an arithmetic processing unit configured to calculate the coordinates of a detection target using different calculation methods according to the state of a variation in the capacitance of the plurality of electrodes,

wherein the arithmetic processing unit calculates the coordinates of the detection target, using one of a centroid calculation method of calculating the coordinates of the centroid and a curve approximation method of calculating a peak of a curve according to a comparison value between a capacitance variation of a peak electrode and a capacitance variation of an electrode which is not adjacent to the peak electrode.

2. The coordinate detecting device according to claim 1,

wherein, when an absolute value of the difference between the capacitance variation of the peak electrode and the capacitance variation of the electrode which is not adjacent to the peak electrode is equal to or less than a predetermined value, the arithmetic processing unit applies the centroid calculation method to electrodes in a first recognition region which includes at least successive electrodes with a capacitance variation equal to or greater than a first threshold value from the peak electrode, thereby calculating the coordinates of the detection target, and

when the absolute value of the difference between the capacitance variation of the peak electrode and the capacitance variation of the electrode which is not adjacent to the peak electrode is greater than the predetermined value, the arithmetic processing unit applies the curve approximation method to electrodes in a second recognition region which includes at least the peak electrode and an electrode adjacent to the peak electrode, thereby calculating the coordinates of the detection target.

3. The coordinate detecting device according to claim 1,

wherein, when an absolute value of the difference between a moving average value of the calculation result of the curve approximation method and the calculation result of the curve approximation method is maintained to be greater than a noise threshold value for a predetermined period or more, the arithmetic processing unit changes the curve approximation method to the centroid calculation method and calculates the coordinates of the detection target, and

the arithmetic processing unit continuously uses the centroid calculation method until the detection target is separated after the absolute value is maintained to be greater than the noise threshold value for the predetermined period or more.

4. The coordinate detecting device according to claim 2,

wherein, when an absolute value of the difference between a moving average value of the calculation result of the curve approximation method and the calculation result of the curve approximation method is maintained to be greater than a noise threshold value for a predetermined period or more, the arithmetic processing unit changes the curve approximation method to the centroid calculation method and calculates the coordinates of the detection target, and

the arithmetic processing unit continuously uses the centroid calculation method until the detection target is separated after the absolute value is maintained to be greater than the noise threshold value for the predetermined period or more.

5. The coordinate detecting device according to claim 1,

wherein the arithmetic processing unit determines a region which includes successive electrodes with a capacitance variation equal to or greater than the first threshold value from the peak electrode and a first electrode or the first and second electrodes with a capacitance variation less than the first threshold value to be a first recognition region.

6. The coordinate detecting device according to claim 2,

wherein the arithmetic processing unit determines a region which includes successive electrodes with a capacitance variation equal to or greater than the first threshold value from the peak electrode and a first electrode or the first and second electrodes with a capacitance variation less than the first threshold value to be the first recognition region.

7. The coordinate detecting device according to claim 3,

wherein the arithmetic processing unit determines a region which includes successive electrodes with a capacitance variation equal to or greater than the first threshold value from the peak electrode and a first electrode or the first and second electrodes with a capacitance variation less than the first threshold value to be the first recognition region.

8. The coordinate detecting device according to claim 4,

wherein the arithmetic processing unit determines a region which includes successive electrodes with a capacitance variation equal to or greater than the first threshold value from the peak electrode and a first electrode or the first and second electrodes with a capacitance variation less than the first threshold value to be the first recognition region.

9. The coordinate detecting device according to claim 1,

wherein the arithmetic processing unit performs the centroid calculation method using the following Expression 1:

XG=(Σ

nX_n/Σ

X_n)×

RESO 

 

[Expression 1]

(where n is an electrode number used in calculation, X_n indicates the capacitance variation of an electrode n, and RESO indicates resolution between the electrodes).

10. The coordinate detecting device according to claim 1,

wherein the arithmetic processing unit uses the curve approximation method, on the basis of the capacitance variations of the peak electrode and two electrodes in the vicinity of the peak electrode, using the following Expression 2:

11. The coordinate detecting device according to claim 1,

wherein the arithmetic processing unit sets, as a second recognition region, a region which includes successive electrodes with a capacitance variation equal to or greater than a second threshold value from the peak electrode and applies the curve approximation method to the region.

12. The coordinate detecting device according to claim 11,

wherein the arithmetic processing unit sets, as the second recognition region, a region which includes successive electrodes with a capacitance variation equal to or greater than a second threshold value from the peak electrode and a first electrode or the first and second electrodes with a capacitance variation less than the second threshold value.

13. The coordinate detecting device according to claim 1,

wherein the arithmetic processing unit sets a predetermined coordinate region including electrodes whose capacitance is changed due to the touch of the detection target among the plurality of electrodes detected by the detecting unit in advance, compares the capacitance variation of the peak electrode and the capacitance variation of the electrode which is not adjacent to the peak electrode among the electrodes in the predetermined coordinate region, and switches the centroid calculation method and the curve approximation method.

14. The coordinate detecting device according to claim 11,

wherein the arithmetic processing unit sets a predetermined coordinate region including electrodes whose capacitance is changed due to the touch of the detection target among the plurality of electrodes detected by the detecting unit in advance, compares the capacitance variation of the peak electrode and the capacitance variation of the electrode which is not adjacent to the peak electrode among the electrodes in the predetermined coordinate region, and switches the centroid calculation method and the curve approximation method.

15. The coordinate detecting device according to claim 12,

wherein the arithmetic processing unit sets a predetermined coordinate region including electrodes whose capacitance is changed due to the touch of the detection target among the plurality of electrodes detected by the detecting unit in advance, compares the capacitance variation of the peak electrode and the capacitance variation of the electrode which is not adjacent to the peak electrode among the electrodes in the predetermined coordinate region, and switches the centroid calculation method and the curve approximation method.

16. The coordinate detecting device according to claim 1, further comprising:

a plurality of orthogonal electrodes arranged in a direction perpendicular to the predetermined direction,

wherein the arithmetic processing unit uses different calculation methods according to the state of a variation in the capacitance of the plurality of orthogonal electrodes detected in the orthogonal direction.

17. A coordinate input device that controls the input of coordinates using the coordinate detecting device according to claim 1.

18. A non-transitory computer readable medium, comprising computer program code stored thereon, executable by one or more digital processor for evaluating quality inspection, wherein the computer program code comprises:

a coordinate detecting program that allows a computer to perform an arithmetic process for determining the coordinates of a detection target on the basis of capacitance variations of a plurality of electrodes which are arranged in a predetermined direction, comprising;

recognizing a peak electrode with the largest capacitance variation from a plurality of detected electrodes;

comparing a capacitance variation of the peak electrode with a capacitance variation of an electrode which is not adjacent to the peak electrode;

applying a centroid calculation method to electrodes in a first recognition region which includes at least successive electrodes with a capacitance variation equal to or greater than a first threshold value from the peak electrode, thereby calculating the coordinates of the detection target, when an absolute value of the difference between the capacitance variation of the peak electrode and the capacitance variation of the electrode which is not adjacent to the peak electrode is equal to or less than a predetermined value; and

applying a curve approximation method to electrodes in a second recognition region which includes at least the peak electrode and an electrode adjacent to the peak electrode, thereby calculating the coordinates of the detection target, when the absolute value of the difference between the capacitance variation of the peak electrode and the capacitance variation of the electrode which is not adjacent to the peak electrode is greater than the predetermined value.

19. The non-transitory computer readable medium, according to claim 18, the coordinate detecting program further comprising:

changing the curve approximation method to the centroid calculation method and calculating the coordinates of the detection target, when an absolute value of the difference between a moving average value of the calculation result of the curve approximation method and the calculation result of the curve approximation method is maintained to be greater than a noise threshold value for a predetermined period or more.