INPUT DEVICE

• US 20070242053A1
• Filed: 04/11/2007
• Published: 10/18/2007
• Est. Priority Date: 04/14/2006
• Status: Active Grant

• Current Assignee: Alps Alpine Co., Ltd.
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Muranaka, Tetsuo
• Granted Patent: US 7,834,860 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• 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

An electrostatic capacitance type input device includes a plurality of electrodes, and detects coordinate position on the basis of a variation in an electrostatic capacitance between the electrodes. The device corrects an erroneous operation in which the device is not properly operated but certain coordinate positions are continuously detected.

Claims

1. An input device comprising:

an input unit having a plurality of electrodes intersecting each other, the respective electrodes being insulated from each other;

a driver configured to select one electrode and apply a potential thereto; and

a control unit configured to acquire a detection value based on a variation in an electrostatic field between the electrodes, and determine if a detection state for detecting a certain coordinate position of the input unit is achieved on the basis of a difference between the detection value and a reference value,

wherein the control unit updates the reference value when the detection state for detecting the same coordinate position is continued and when it is determined that the difference between the detection value and the reference value is less than or equal to a predetermined updated detection range.

2. The input device according to claim 1, wherein the reference value is updated to have the same value as the detection value.

3. The input device according to claim 1, wherein the control unit stores a predetermined detection range and determines that the detection state is achieved, when it is determined that the difference between the detection value and the reference value is greater than or equal to the predetermined detection range.

4. The input device according to claim 1, wherein the control unit monitors the detection value every predetermined monitoring time when the detection state has been achieved, and compares the difference between the detection value and the reference value with the predetermined updated detection range when it is determined that the detection state for detecting the same coordinate position is continued for a predetermined number of monitoring times.

5. The input device according to claim 1, wherein the control unit determines if the operator is approaching the input unit and generates coordinates data on the basis of the detection value when judging that the difference between the detection value and the reference value is equal to or greater than the predetermined update detection range.

6. The input device according to claim 1, wherein the reference value is set for each electrode supplied with the potential.

7. The input device according to claim 1, wherein the input unit further includes

a plurality of X electrodes and Y electrodes, which are insulated from each other and intersect each other;

detection electrodes positioned between adjacent X electrodes or between adjacent Y electrodes;

an X driver configured to sequentially select and apply a potential to the X electrodes;

a Y driver configured to sequentially select and apply a potential to the Y electrodes; and

wherein the detection unit detects a potential difference between the X electrode supplied and the corresponding detection electrode or a potential difference between the Y electrode and the corresponding detection electrode.

8. The input device according to claim 7, wherein the X electrodes are formed on a first surface of a substrate made of a resin sheet, the Y electrodes are formed on a second surface of the substrate, and the detection electrodes are formed on the first or second surface of the substrate.