Proximity detection device

Patent metadata

Field	Value
Publication number	US-2024028165-A1
Application number	US-202318479639-A
Country	US
Kind code	A1
Filing date	Oct 2, 2023
Priority date	Apr 30, 2021
Publication date	Jan 25, 2024
Grant date	—

Abstract

A proximity detection device with a detection distance for detecting an object separated to some extent from an operation surface is provided. The proximity detection device includes a proximity detection unit that has a piezoelectric body and first and second electrodes disposed in contact with the piezoelectric body to detect proximity of an object, a signal applying unit that causes the proximity detection unit to perform capacitance detection and ultrasonic transmission and/or ultrasonic reception by applying a plurality of signals of different frequencies to at least one of the first and second electrodes, and a charge measurement unit connected to at least one of the first and second electrodes to measure electric charge.

First claim

What is claimed is:

1 . A proximity detection device, comprising:
a proximity detection unit that has a piezoelectric body and first and second electrodes disposed in contact with the piezoelectric body to detect proximity of an object; a signal applying unit that causes the proximity detection unit to perform capacitance detection and ultrasonic transmission and/or ultrasonic reception by applying a plurality of signals of different frequencies to at least one of the first and second electrodes; and a charge measurement unit connected to at least one of the first and second electrodes to measure electric charge.

2 . The proximity detection device according to claim 1 , wherein the proximity detection unit is configured such that the piezoelectric body is sandwiched between the first electrode and the second electrode.

3 . The proximity detection device according to claim 1 , wherein the proximity detection unit performs the ultrasonic transmission followed by the ultrasonic reception of reflected waves.

4 . The proximity detection device according to claim 1 , further comprising:
a calculation unit that calculates a distance between the object and the proximity detection unit, wherein the signal applying unit selectively applies a first frequency signal for capacitance detection and a second frequency signal for ultrasonic transmission, and the calculation unit obtains a result of capacitance detection and/or ultrasonic detection based on the signal selected by the signal applying unit and the electric charge measured by the charge measurement unit, and calculates a distance between the object and the proximity detection unit based on the obtained result.

5 . The proximity detection device according to claim 4 , wherein the calculation unit obtains a result of capacitance detection based on the amount of electric charge measured by the charge measurement unit when the first frequency signal is selected by the signal applying unit, and calculates a distance between the object and the proximity detection unit based on the obtained result.

6 . The proximity detection device according to claim 4 , wherein the calculation unit calculates, when the second frequency signal is selected by the signal applying unit, a distance between the object and the proximity detection unit based on a period of time from ultrasonic transmission to ultrasonic reception based on the electric charge measured by the charge measurement unit.

7 . The proximity detection device according to claim 4 , wherein the signal applying unit selects the second frequency signal and causes the proximity detection unit to perform the ultrasonic transmission and/or the ultrasonic reception, and when a distance between the object and the proximity detection unit calculated by the calculation unit is equal to or shorter than a predetermined distance, selects the first frequency signal and causes the proximity detection unit to perform the capacitance detection.

8 . The proximity detection device according to claim 4 , wherein the signal applying unit performs switching between the first frequency signal and the second frequency signal in a time-division manner.

9 . The proximity detection device according to claim 4 , further comprising:
a timer that measures a period of time from the application of the second frequency signal by the signal applying unit to the measurement of the electric charge based on the second frequency signal reflected by the object, wherein the calculation unit calculates the distance between the object and the proximity detection unit based on the period of time measured by the timer.

10 . The proximity detection device according to claim 4 , wherein the calculation unit detects a two-dimensional profile or a three-dimensional image of the object based on the amount of electric charge measured by the charge measurement unit and/or the period of time from the ultrasonic transmission and the ultrasonic reception.

11 . The proximity detection device according to claim 1 , comprising:
a plurality of the first electrodes; one or more of the piezoelectric bodies and; a plurality of the second electrodes, wherein each of the one or more piezoelectric bodies is disposed between at least one of the plurality of first electrodes and at least one of the plurality of second electrodes.

12 . The proximity detection device according to claim 1 , wherein
the first electrodes extend in a first direction and are arranged in a plurality of arrays in a second direction that intersects with the first direction, the plurality of second electrodes extend in the second direction and are arranged in a plurality of arrays in the first direction, and the piezoelectric bodies are sandwiched between the first and second electrodes at points where the first and second electrodes intersect with each other.

13 . The proximity detection device according to claim 1 , further comprising a third electrode disposed on an opposite side of a side where the object approaches relative to the first and second electrodes.

14 . The proximity detection device according to claim 13 , wherein the third electrode is connected to the ground.

15 . The proximity detection device according to claim 13 , wherein the signal applying unit applies a third frequency signal to the third electrode.

16 . The proximity detection device according to claim 1 , wherein the piezoelectric body is an electret having piezoelectric properties.

Assignees

• Alps Alpine Co Ltd

Inventors

• Shigetaka Hiroshi
• Fujiyoshi Tatsumi

Classifications

• G06V40/1306

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• G06F3/0436

  in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate · CPC title

• G06F3/0414

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