Capacitive touch panel device

• US 8,350,826 B2
• Filed: 04/29/2010
• Issued: 01/08/2013
• Est. Priority Date: 05/14/2009
• Status: Active Grant

• Current Assignee: Kyocera Corporation
• Original Assignee: Optrex Corporation (Kyocera Corporation)
• Inventors: Watanabe, Kiyoshi
• Primary Examiner(s): Eisen, Alexander
• Assistant Examiner(s): Patel, Sanjiv D
• Application Number:
  US12/769,922
• Publication Number:
  US 20100289769A1
• Time in Patent Office: 985 Days
• Field of Search: 345173-178, 178 1801- 2004, 324/658, 324/662
• 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 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• 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

Disclosed is a capacitive touch panel device having a sensing control unit that performs a scan sequence on individual sensor electrodes to measure sensor output values. The sensing control unit exercises control to measure sensor output values, with setup performed to avoid the detection of sensitivity slope, by executing a first scan sequence on all sensor electrodes. If the result of the first scan sequence indicates that multiple points are touched, the sensing control unit exercises control to measure sensor output values again, with setup performed to allow the detection of sensitivity slope, by executing a second scan sequence on the sensor electrodes related to a plurality of touch position candidate coordinates derived from multiple point touches, and identify and eliminate erroneously detected coordinates in accordance with the sensor output values measured upon the execution of the second scan sequence and with the tendency of sensitivity slope.

Claims

1. A capacitive touch panel device comprising:

a capacitive touch panel which has sensor electrodes arranged in the x and y directions; and

a sensing control unit which controls the execution of a scan sequence to measure a sensor output value that is obtained by quantifying a change in the capacitance generated between the sensor electrode mounted in the capacitive touch panel and a conductive body positioned close to the sensor electrode;

wherein, the sensing control unit exercises control to;

measure sensor output values, with setup performed to avoid the detection of sensitivity slope, by executing a first scan sequence on all the sensor electrodes mounted in the capacitive touch panel,

if the result of the first scan sequence indicates that multiple points are touched, measure sensor output values again, with setup performed to allow the detection of sensitivity slope, by executing a second scan sequence on the sensor electrodes related to a plurality of touch position candidate coordinates derived from the multiple point touches, and

identify and eliminate erroneously detected coordinates in accordance with the sensor output values measured upon the execution of the second scan sequence and with the tendency of sensitivity slope.

2. The capacitive touch panel device according to claim 1,

wherein, when multiple points are found to be touched, the sensing control unit exercises control to perform setup to allow the detection of sensitivity slope, measure sensor output values again by executing the second scan sequence on the sensor electrodes that are arranged in the at least one of the x direction and the y direction, the sensor electrodes being found to be touched, and identify and eliminate erroneously detected coordinates in accordance with the magnitude relationship between the sensor output values of the sensor electrodes, which are measured upon the execution of the second scan sequence, and with the tendency of sensitivity slope.

3. The capacitive touch panel device according to claim 1,

wherein, when multiple points are found to be touched, the sensing control unit exercises control to perform setup to allow the detection of sensitivity slope, measure sensor output values again by executing the second scan sequence on one or more sensor electrodes related to a plurality of touch position candidate coordinates derived from the multiple point touches, and identify and eliminate erroneously detected coordinates in accordance with the magnitude relationship between the sensor output values of the sensor electrodes, which are measured upon the execution of the second scan sequence, and position-specific expected sensor output values of a predetermined sensor electrode and with the tendency of sensitivity slope.

4. The capacitive touch panel device according to claim 1, further comprising:

a switching circuit which is provided in a path connecting the sensor electrodes arranged in the at least one of the x direction and the y direction to a sensing circuit group for measuring sensor output values of destination sensor electrodes, the switching circuit being capable of switching between a route without internal resistance and a route with internal resistance;

wherein, when executing the first scan sequence, the sensing control unit performs setup to avoid the detection of sensitivity slope by causing the switching circuit to select the route without internal resistance; and

wherein, when executing the second scan sequence, the sensing control unit performs setup to allow the detection of sensitivity slope by causing the switching circuit to select the route with internal resistance.

5. The capacitive touch panel device according to claim 2, further comprising:

a switching circuit which is provided in a path connecting the sensor electrodes arranged in the at least one of the x direction and the y direction to a sensing circuit group for measuring sensor output values of destination sensor electrodes, the switching circuit being capable of switching between a route without internal resistance and a route with internal resistance;

wherein, when executing the first scan sequence, the sensing control unit performs setup to avoid the detection of sensitivity slope by causing the switching circuit to select the route without internal resistance; and

wherein, when executing the second scan sequence, the sensing control unit performs setup to allow the detection of sensitivity slope by causing the switching circuit to select the route with internal resistance.

6. The capacitive touch panel device according to claim 3, further comprising:

a switching circuit which is provided in a path connecting the sensor electrodes arranged in the at least one of the x direction and the y direction to a sensing circuit group for measuring sensor output values of destination sensor electrodes, the switching circuit being capable of switching between a route without internal resistance and a route with internal resistance;

wherein, when executing the first scan sequence, the sensing control unit performs setup to avoid the detection of sensitivity slope by causing the switching circuit to select the route without internal resistance; and

wherein, when executing the second scan sequence, the sensing control unit performs setup to allow the detection of sensitivity slope by causing the switching circuit to select the route with internal resistance.

7. The capacitive touch panel device according to claim 1, further comprising:

a current-limiting circuit which limits the current flowing from a constant current source for applying a capacitance change to a sensor electrode;

wherein, when executing the first scan sequence, the sensing control unit performs setup to avoid the detection of sensitivity slope by exercising control to inhibit the current-limiting circuit from providing current control; and

wherein, when executing the second scan sequence, the sensing control unit performs setup to allow the detection of sensitivity slope by exercising control to let the current-limiting circuit provide current control.

8. The capacitive touch panel device according to claim 2, further comprising:

a current-limiting circuit which limits the current flowing from a constant current source for applying a capacitance change to a sensor electrode;

wherein, when executing the first scan sequence, the sensing control unit performs setup to avoid the detection of sensitivity slope by exercising control to inhibit the current-limiting circuit from providing current control; and

wherein, when executing the second scan sequence, the sensing control unit performs setup to allow the detection of sensitivity slope by exercising control to let the current-limiting circuit provide current control.

9. The capacitive touch panel device according to claim 3, further comprising:

a current-limiting circuit which limits the current flowing from a constant current source for applying a capacitance change to a sensor electrode;

wherein, when executing the first scan sequence, the sensing control unit performs setup to avoid the detection of sensitivity slope by exercising control to inhibit the current-limiting circuit from providing current control; and

wherein, when executing the second scan sequence, the sensing control unit performs setup to allow the detection of sensitivity slope by exercising control to let the current-limiting circuit provide current control.

10. A capacitive touch panel device comprising:

a capacitive touch panel which has sensor electrodes that are arranged in at least one direction; and

a sensing control unit which controls the execution of a scan sequence to measure a sensor output value that is obtained by quantifying a change in the capacitance generated between the sensor electrode mounted in the capacitive touch panel and a conductive body positioned close to the sensor electrode;

wherein, the sensing control unit exercises control to perform setup to allow the detection of sensitivity slope, and execute the scan sequence for detecting position coordinates of a sensor electrode where the conductive body positioned close to the sensor electrode.