INPUT DEVICE

• US 20070001681A1
• Filed: 06/15/2006
• Published: 01/04/2007
• Est. Priority Date: 06/29/2005
• Status: Active Grant

• Current Assignee: Alps Alpine Co., Ltd.
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Sato, Kunio
• Granted Patent: US 7,279,904 B2
• Time in Patent Office: Days
• US Class Current: 324/457
• CPC Class Codes: H03K 17/9502 Measures for increasing reliability
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/96072 Phase comparison, i.e. where a phase comparator receives at one input the signal directly from the oscillator, at a second input the same signal but delayed, with a delay depending on a sensing capacitance

Abstract

Provided is an input device capable of determining an output signal according to approach or contact of a portion of a human body and an output signal including noise to perform an input operation, although the output signal output from an electrostatic sensor includes the noise.

The input device includes an input electrostatic sensor 2 which detects whether a portion of a human body approaches or makes contact by change in capacitance, a noise detection electrostatic sensor 3 which is provided on the periphery of the input electrostatic sensor 2 and detects change in capacitance which is generated by a cause different from the approach or the contact of the portion of the human body, and a control means 9 which compares an output signal obtained from the input electrostatic sensor 2 with a noise signal obtained from the noise detection electrostatic sensor 3, determines the output signal obtained from the cause different from the approach or the contact of the potion of the human body to a noise component, and controls an input operation.

Claims

1. An input device comprising:

an input electrostatic sensor;

a noise detection electrostatic sensor; and

a control means that compares an output signal obtained from the input electrostatic sensor with a noise signal obtained from the noise detection electrostatic sensor, determines the output signal obtained from the cause different from the approach or the contact of the potion of the human body to a noise component, and controls an input operation.

2. The input device according to claim 1, wherein the input electrostatic sensor detects whether a portion of a human body approaches or makes contact by a change in capacitance.

3. The input device according to claim 1, wherein the noise detection electrostatic sensor is provided on the periphery of the input electrostatic sensor and detects the change in capacitance that is generated by a noise different from the approach or the contact of the portion of the human body.

4. The input device according to claim 1,

wherein the input electrostatic sensor detects whether a portion of a human body approaches or makes contact by a change in capacitance;

and

wherein the noise detection electrostatic sensor is provided on the periphery of the input electrostatic sensor and detects the change in capacitance that is generated by a noise different from the approach or the contact of the portion of the human body.

5. The input device according to claim 1, wherein the noise detection electrostatic sensor has a detection surface larger than that of the input electrostatic sensor.

6. The input device according to claim 4, wherein the noise detection electrostatic sensor has a detection surface larger than that of the input electrostatic sensor.

7. The input device according to claim 4, wherein the noise detection electrostatic sensor has a protective cover that prevents the portion of the human body from approaching or making contact with the noise detection electrostatic sensor, and

wherein the protective cover has a thickness that the noise detection electrostatic sensor does not react to when the portion of the human body makes contact with the protective cover and a thickness that the noise detection electrostatic sensor reacts to when the control means cannot determine the noise component.

8. The input device according to claim 4, comprising:

a low frequency clock signal generating means that generates a low frequency clock signal;

an input delay means that generates an input delay signal obtained by applying delay according to the change in capacitance of the input electrostatic sensor to the low frequency clock signal;

a high frequency signal generating means that generates a high frequency clock signal;

a noise detection delay means that generates a noise detection delay signal obtained by applying delay according to change in capacitance of the noise detection electrostatic sensor to the high frequency clock signal;

a logical product means that receives the low frequency clock signal, the input delay signal, the high frequency clock signal, and the noise detection delay signal and outputs the output signal or the noise signal;

a smoothing means that smoothes the output signal or the noise signal;

an A/D converting means that converts the output signal and the noise signal output from the smoothing means into respective digital signal; and

the control means that compares the output signal with the noise signal, both of which are converted into the respectively digital signals and determines the noise component.

9. The input device according to claim 4, wherein the control means changes a threshold value that determines whether the portion of the human body approaches or makes contact in correspondence with the noise component included in the output signal obtained by comparing the output signal with the noise signal.

10. The input device according to claim 4, wherein the control means determines whether the output signal transmitted to the control means is obtained from a noise different from the approach or the contact of the portion of the human.

11. The input device according to claim 10, wherein the determination whether the output signal transmitted to the control means is obtained from a noise different from the approach or the contact of the portion of the human depends on whether a predetermined time lapses after the output signal is received or a step number obtained from the output signal is a predetermined step number.