CAPACITANCE TYPE TOUCH PANEL

• US 20160070388A1
• Filed: 11/15/2015
• Published: 03/10/2016
• Est. Priority Date: 09/04/2014
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Tokai RIKA Denki Seisakusho, SMK Corporation
• Original Assignee: Kabushiki Kaisha Tokai RIKA Denki Seisakusho, SMK Corporation
• Inventors: YOSHIKAWA, Osamu, IMAI, Takao
• Granted Patent: US 9,696,862 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• 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 capacitance type touch panel is provided which distinguishes a noise signal with ease and detects an input operation position with high accuracy, without extensively modifying the structure of a touch panel. The capacitance type touch panel is provided with capacitance change judgment unit for comparing a voltage variation level R(n,m) of a detection electrode S(n) detected by capacitance detection unit with a detection threshold value. If the voltage variation levels R(n,m) of all the detection electrodes S(n) are equal to or more than the detection threshold value while outputting a detection signal to any drive area DV(m), it is assumed that noise occurs for the long period of outputting the detection signal to the drive area DV(m), and position detection unit does not detect the input operation position.

Claims

1. A capacitance type touch panel comprising:

a plurality of detection electrodes that are arranged in an input operation area, which is sufficiently wider than a width of an input operation member in a first direction of an insulation panel, at a regular pitch in the first direction along a second direction orthogonal to the first direction;

a detection signal generating circuit for generating an alternating current detection signal at a predetermined voltage level;

a plurality of drive areas that are arranged at a regular pitch in the second direction of the insulation panel along the first direction, the plurality of drive areas each intersecting with all of the plurality of detection electrodes at an insulation distance away;

a drive control unit for selecting a specific one of the plurality of drive areas, and outputting a detection signal to the selected drive area;

electrode selection unit for sequentially selecting a specific one of the plurality of detection electrodes;

capacitance detection unit for detecting a detection voltage appearing due to the detection signal in the detection electrode selected by the electrode selection unit while the detection signal is output to the drive area selected by the drive control unit, and detecting a voltage variation level in the detection voltage from a state without approach of the input operation member;

position detection unit for identifying the detection electrode having the voltage variation level equal to or more than a predetermined input judgment threshold value and the drive area, to which the detection signal is output, in the vicinity of the detection electrode, owing to a change in capacitance of the selected detection electrode and the drive area to which the detection signal is output, in the vicinity of the detection electrode by approach of the input operation member, the position detection unit detecting an input operation position of the input operation member in the first and second directions, on the basis of an arrangement position of the identified detection electrode on the insulation panel in the first direction and an arrangement position of the identified drive area on the insulation panel in the second direction; and

capacitance change judgment unit for comparing the voltage variation level of the detection electrode detected by the capacitance detection unit with a detection threshold value that is set at a predetermined value less than the input judgment threshold value, wherein

if the voltage variation levels of all detection electrodes selected by the electrode selection unit are equal to or more than the detection threshold value while the drive control unit outputs the detection signal to any selected drive area, the position detection unit does not detect the input operation position even when the voltage variation level of any detection electrode exceeds the input judgment threshold value.

2. The capacitance type touch panel according to claim 1, wherein the detection threshold value is set at a value higher than at least the voltage variation level of the detection voltage occurring in the detection electrode owing to a base noise.

3. The capacitance type touch panel according to claim 2, wherein the input judgment threshold value is set at twice or more the detection threshold value.