# US 9,435,704 B2 · Shock recording device

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- Number: US 9,435,704 B2
- Document ID: US9435704B2
- Status: Granted
- Kind: B2
- Application number: 14/623,076
- Filed: 2015-02-16
- Published: 2015-08-27
- Granted: 2016-09-06
- Earliest claimed: 2014-02-25
- Assignees: Panasonic Intellectual Property Management Co., Ltd.
- Applicants: Panasonic Intellectual Property Management Co., Ltd.
- Inventors: Michihito Ueda; Yukihiro Kaneko; Yu Nishitani; Atsushi Omote
- Web page: https://patentgrep.com/patent/US9435704B2

## CPC

- G01L 5/0052: {measuring forces due to impact (G01L5/0061, G01L5/14 take precedence; impact testing of structures G01M7/08; impact testing of material G01N3/00)}
- G01L 1/18: using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
- G01L 1/2293: {of the semi-conductor type}
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)

## Abstract

The present invention provides a shock recording device, comprising: a vibration energy harvester comprising a first electrode and a second electrode, the vibration energy harvester converting an energy of a shock applied thereto into a potential difference between the first electrode and the second electrode; and a ferroelectric transistor comprising a gate electrode, a source electrode, and a drain electrode, the ferroelectric transistor further comprising a stacked structure of a ferroelectric layer and a semiconductor layer. The gate electrode is electrically connected to the first electrode. The source electrode is electrically connected to the second electrode. This shock recording device does not need a power source used to record a shock.

## Claims

### Claim 1

A method for determining whether or not a shock was applied to a shock recording device, the method comprising:
(a) preparing the shock recording device comprising:
a vibration energy harvester comprising a first electrode and a second electrode, the vibration energy harvester converting an energy of a shock applied thereto into a potential difference between the first electrode and the second electrode; and
a ferroelectric transistor comprising a gate electrode, a source electrode, and a drain electrode, the ferroelectric transistor further comprising a stacked structure of a ferroelectric layer and a semiconductor layer,
wherein
the gate electrode is electrically connected to the first electrode; and
the source electrode is electrically connected to the second electrode;
(b) measuring a resistance value of the semiconductor layer through the drain electrode and the source electrode; and
(c) determining whether or not a shock was applied to the shock recording device based on the resistance value, and
wherein the shock recording device further comprises a zener diode which is electrically connected to the source electrode and the drain electrode.

### Claim 2 (depends on 1)

The method according to claim 1, wherein
the shock recording device further comprises a resistance;
one end of the resistance is electrically connected to the gate electrode; and
the other end of the resistance is electrically connected to the zener diode and the vibration energy harvester.

### Claim 3 (depends on 2)

The method according to claim 2, wherein
the ferroelectric transistor has a gate capacitance CG;
the resistance has a resistance value R;
the following mathematical formula (I) is satisfied:
0.7 milliseconds≦time constant τ(second)≦7.0 milliseconds (I)
where the time constant τ (second) is equal to the product of (the resistance value R)·(the gate capacitance CG).

### Claim 4 (depends on 3)

The method according to claim 3, wherein in the step (c), the number of shocks applied to the shock recording device is also determined based on the resistance value.

### Claim 5 (depends on 1)

The method according to claim 1, further comprising:
(z1) connecting a reset voltage generation circuit comprising a DC power source and a switch element in series so that one end of the DC power source and one end of the switch element are electrically connected to the drain electrode and the gate electrode, respectively; and
(z2) turning the switch element on to apply a voltage difference between the drain electrode and the gate electrode,
wherein the steps (z1) and (z2) are conducted before the step (a).