Device for detecting holding state of an object

Patent metadata

Field	Value
Publication number	US-10378973-B2
Application number	US-201715454155-A
Country	US
Kind code	B2
Filing date	Mar 9, 2017
Priority date	Sep 12, 2014
Publication date	Aug 13, 2019
Grant date	Aug 13, 2019

Abstract

A device for detecting a holding state of an object. The device includes a housing for the object that has a shape that can be held by an operator and a piezoelectric sensor attached to the housing. Moreover, a detecting unit can detects a holding state of the housing by using a fluctuation amount of an output voltage of the piezoelectric sensor. The housing has a shape having a hollow space and the piezoelectric sensor has a flat film shape and is disposed in contact with an inner wall surface of the housing. The piezoelectric film produces charges when stretched and contracted in response to a displacement of the housing that are outputted as a voltage to the detecting unit. When detecting that the output voltage significantly fluctuates, the detecting unit identifies that the object is being held.

First claim

The invention claimed is:

1. A device for detecting a holding state of an object, the device comprising:
a housing for the object having a shape adapted to be held by an operator;
a piezoelectric sensor attached to the housing and configured to generate an output voltage; and
a detecting unit communicatively coupled to the piezoelectric sensor and configured to detect a holding state of the object based on a fluctuation amount of the output voltage generated by the piezoelectric sensor,
wherein the detecting unit is configured to determine that the object is being held by the operator when the fluctuation amount is larger than a preset hold detection threshold, and
wherein the detecting unit is further configured to:
detect a first time when the output voltage is a maximum value,
detect a second time when the output voltage is a minimum value,
calculate a time interval between the first and second times,
determine if the calculated time interval is longer than an operation control time threshold, and
start an operation executed by the object if the time interval is longer than the operation control time threshold.

2. The device according to claim 1 , wherein the piezoelectric sensor includes:
a piezoelectric film having a flat film shape; and
a conductor film that extracts a charge produced by the piezoelectric film when the piezoelectric film is stretched and contracts.

3. The device according to claim 2 , wherein the output voltage generated by the piezoelectric sensor is based on the extracted charge.

4. The device according to claim 2 , wherein the piezoelectric film comprises polylactic acid as a main component and is stretched in a uniaxial direction when the operator holds the housing.

5. The device according to claim 1 ,
wherein the housing has either a cylindrical shape or a box shape, and
the piezoelectric sensor is attached to an inner wall surface of the housing.

6. The device according to claim 5 , wherein the piezoelectric sensor includes:
a base film;
a detection conductor disposed on the base film;
a piezoelectric sheet disposed on the detection conductor;
a first ground electrode disposed on the piezoelectric sheet;
a second ground electrode disposed on the base film opposite the detection conductor; and
a pair of protection films disposed on the first and second ground electrodes, respectively.

7. The device according to claim 6 , wherein the detecting unit includes a base substrate and electronic components coupled to the detection conductor by terminal conductors and wiring conductors disposed on the base film.

8. The device according to claim 1 , further comprising a low-pass filter disposed between the piezoelectric sensor and the detecting unit and having a cutoff frequency adapted to cut of signals having a frequency indicative of at least one of vibration and shock applied to the object.

9. A device for detecting a holding state of an object, the device comprising:
a housing for the object having a shape adapted to be held by an operator;
a piezoelectric sensor attached to an inner wall surface of the housing and configured to generate an output voltage; and
a detecting unit communicatively coupled to the piezoelectric sensor and configured to detect a holding state of the object based on a fluctuation amount of the output voltage generated by the piezoelectric sensor,
wherein the piezoelectric sensor includes:
a base film;
a detection conductor disposed on the base film;
a piezoelectric sheet disposed on the detection conductor;
a first ground electrode disposed on the piezoelectric sheet;
a second ground electrode disposed on the base film opposite the detection conductor; and
a pair of protection films disposed on the first and second ground electrodes, respectively, with the protection film disposed on the second ground electrode having a shorter length than the second ground electrode, such that the second ground electrode is secured to the inner wall surface of the housing by a conductive adhesive member.

10. The device according to claim 9 , wherein the detecting unit determines that the object is being held by the operator when the fluctuation amount is larger than a preset hold detection threshold.

11. The device according to claim 10 , wherein the detecting unit further determines that the object has been released by the operator when the fluctuation amount becomes smaller than the preset hold detection threshold after the fluctuation amount was determined to be larger than the preset hold detection threshold.

12. The device according to claim 10 , wherein the detecting unit is configured to start an operation executed by the object when the detecting unit determines that the output voltage is larger than a preset operation control threshold.

13. The device according to claim 10 , wherein the detecting unit is configured to start an operation executed by the object when the detecting unit determines that the output voltage is larger than a preset first operation control threshold and then the detecting unit determines that the output voltage is smaller than a preset second operation control threshold.

14. The device according to claim 10 , wherein the detecting unit is further configured to:
detect a first time when the output voltage is a maximum value,
detect a second time when the output voltage is a minimum value,
calculate a time interval between the first and second times,
determine if the time interval is longer than an operation control time threshold, and
start an operation executed by the object if the time interval is longer than the operation control time threshold.

15. A method for detecting a holding state of an object having a housing adapted to be held by an operator, the method comprising:
generating, by a piezoelectric sensor attached to the housing, an output voltage;
detecting, by a detecting unit coupled to the piezoelectric sensor, a holding state of the object based on a fluctuation amount of the output voltage generated by the piezoelectric sensor;
determining, by the detecting unit, that the object is being held by the operator when the fluctuation amount is larger than a preset hold detection threshold;
detecting, by the detecting unit, a first time when the output voltage is a maximum value;
detecting, by the detecting unit, a second time when the output voltage is a minimum value;
calculating, by the detecting unit, a time interval between the first and second times;
determining, by the detecting unit, if the time interval is longer than an operation control time threshold; and
starting, by the detecting unit, an operation executed by the object if the time interval is longer than the operation control time threshold.

16. The method according to claim 15 , further comprising determining, by the detecting unit, that the object has been released by the operator when the fluctuation amount becomes smaller than the preset hold detection threshold after the fluctuation amount was determined to be larger than the preset hold detection threshold.

17. The method according to claim 15 , further comprising starting, by the detecting unit, an operation executed by the object when the output voltage is larger than a preset operation control threshold.

18. The method according to claim 15 , further comprising starting, by the detecting unit, an operation executed by the object when the output voltage is larger than a preset first operation control threshold and then the output voltage is smaller than a preset second operation control threshold.

Assignees

• Murata Manufacturing Co

Inventors

• Kihara Takashi
• Ando Masamichi
• Kitada Hiroaki
• Endo Jun
• Yamaguchi Yoshihiro

Classifications

• G01L1/2287

  constructional details of the strain gauges (adjustable resistors H01C10/00) · CPC title

• G01L1/16 Primary

  using properties of piezoelectric devices · CPC title

• G06F3/03545

  Pens or stylus · CPC title