# US 7,607,829 B2 · Resonance tag with temperature sensor

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- Number: US 7,607,829 B2
- Document ID: US7607829B2
- Status: Granted
- Kind: B2
- Application number: 11/945,259
- Filed: 2007-11-26
- Published: 2008-10-23
- Granted: 2009-10-27
- Earliest claimed: 2006-12-06
- Assignees: Canon Kabushiki Kaisha
- Inventors: Takayuki Sumida; Tadahiko Hirai
- Web page: https://patentgrep.com/patent/US7607829B2

## CPC

- G01K 11/08: of disposable test bodies, e.g. cone
- G01K 7/32: using change of resonant frequency of a crystal
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)

## Abstract

A temperature-history sensor includes a resonance circuit composed of at least a capacitor and a coil. The temperature-history sensor has a display for indicating a predetermined set temperature of the temperature-history sensor. The capacitor has at least a thermofusion material between electrodes of the capacitor, and the melting point of the thermofusion material is in the region of the set temperature.

## Claims

### Claim 1

A temperature-history sensor comprising:
a resonance circuit comprising:
a capacitor; and
a coil;
a thermofusion material;
a reservoir portion for stocking the thermofusion material;
a flow path for supplying the thermofusion material from the reservoir portion to between electrodes of the capacitor; and
a display for indicating a predetermined set temperature of the temperature-history sensor,
wherein a melting point of the thermofusion material is in a region of the set temperature, and
wherein at least a part of the thermofusion material fuses due to heat and flows to between the electrodes of the capacitor so as to change an effective dielectric constant of the capacitor.

### Claim 2 (depends on 1)

The temperature-history sensor according to claim 1, wherein the region of the set temperature is a range from a temperature 0.5° C. lower than the set temperature to the set temperature.

### Claim 3 (depends on 1)

The temperature-history sensor according to claim 1, wherein the display indicates the predetermined set temperature by one of the following methods: an electrical method; a magnetic method; an optical method; and a method by using printing.

### Claim 4 (depends on 1)

The temperature-history sensor according to claim 1, wherein the capacitor comprises a porous dielectric between the capacitor electrodes.

### Claim 5

A temperature-history sensor comprising:
a resonance circuit comprising:
a capacitor; and
a coil;
wherein a change of an effective dielectric constant of the capacitor changes a resonance characteristic of the resonance circuit,
wherein the capacitor includes a pair of electrodes which face each other and are separate from each other via a gap,
wherein a first material becomes fluidized at a first temperature and moves into the gap or to outside of the gap, so that an effective dielectric constant is changed, and as a result, the resonance circuit has a first resonance characteristic, and
wherein a second material becomes fluidized at a second temperature which is higher than the first temperature and moves into the gap or to outside of the gap, so that the effective dielectric constant is changed, and as a result, the resonance circuit has a second resonance characteristic.