Touch Type Operation Input Device

• US 20140292699A1
• Filed: 06/13/2014
• Published: 10/02/2014
• Est. Priority Date: 12/16/2011
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Ando, Masamichi
• Granted Patent: US 10,620,747 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells
• CPC Class Codes: H03K 17/9643 using a plurality of detectors, e.g. keyboard

Abstract

A touch type operation input device capable of accurately detecting pressing force with which an operator presses is provided. The touch type operation input device includes a touch panel including a piezoelectric sensor and a touch sensor, and a pressing force detection unit. Until the pressing force detection unit detects a position detection signal given by the touch sensor, the pressing force detection unit causes a reference voltage of the pressing force detection to follow an output voltage of the piezoelectric sensor to be the same as the output voltage of the piezoelectric sensor. When the pressing force detection unit obtains the position detection signal given by the touch sensor, the pressing force detection unit fixes the reference voltage. The pressing force detection unit calculates a pressing force detection voltage from the difference between the output voltage and the fixed reference voltage, and detects the pressing force.

Claims

1. A touch type operation input device comprising:

a piezoelectric sensor configured to generate an output voltage in accordance with a pressing force;

a touch sensor configured to detect an operation input; and

a pressing force detection unit configured to detect pressing force on the basis of the output voltage of the piezoelectric sensor,

when the pressing force detection unit obtains a detection result indicating that the operation input on the basis of an output signal from the touch sensor is above a predetermined value, the pressing force detection unit fixes a reference voltage, and detects the pressing force from a difference between the output voltage and the reference voltage.

2. The touch type operation input device according to claim 1, wherein when the pressing force detection unit fails to obtain the detection result indicating that the operation input on the basis of the output signal from the touch sensor is above the predetermined value, the pressing force detection unit causes the reference voltage to be the same as the output voltage of the piezoelectric sensor.

3. The touch type operation input device according to claim 1, wherein when the output signal indicating a pressed position from the touch sensor is the same for a predetermined period of time or more, the pressing force detection unit determines to have obtained the detection result indicating that the operation input is above the predetermined value.

4. The touch type operation input device according to claim 2, wherein when the pressing force detection unit does not detect the output signal indicating a pressed position from the touch sensor, the pressing force detection unit stops the pressing force detection.

5. The touch type operation input device according to claim 4, wherein when the pressing force detection unit detects the output signal indicating the pressed position from the touch sensor, the pressing force detection unit starts pressing force detection.

6. The touch type operation input device according to claim 1, wherein the pressing force detection unit corrects the pressing force detected from the output voltage in accordance with a pressed position on a touch surface indicated by the output signal from the touch sensor.

7. The touch type operation input device according to claim 6, wherein the pressing force detection unit performs correction to increase a sensitivity on the basis of a distance between a center of the touch surface and the position on the touch surface indicated by the output signal indicating the pressed position.

8. The touch type operation input device according to claim 1, wherein the touch sensor and the piezoelectric sensor include:

a flat film-shaped piezoelectric film including a first principal surface and a second principal surface facing each other;

an electrostatic capacitance detection electrode on at least one of the first principal surface and the second principal surface of the piezoelectric film; and

a piezoelectric voltage detection electrode on the first principal surface and the second principal surface of the piezoelectric film.

9. A touch type operation input device according to claim 8, wherein the piezoelectric film is polylactic acid which had been subjected to stretching processing in at least one axis direction.