# US 6,271,538 B1 · High-frequency detecting elements and high-frequency heater using the same

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- Number: US 6,271,538 B1
- Document ID: US6271538B1
- Status: Granted
- Kind: B1
- Application number: 08/980,017
- Filed: 1997-11-26
- Published: 2001-06-14
- Granted: 2001-08-07
- Earliest claimed: 1994-11-28
- Assignees: Murata Manufacturing Co., Ltd.
- Inventors: Hideaki Niimi; Yuichi Takaoka
- Web page: https://patentgrep.com/patent/US6271538B1

## CPC

- H05B 6/6447: {Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors}
- G01K 7/22: the element being a non-linear resistance, e.g. thermistor (G01K7/26 takes precedence)
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)

## Abstract

A high-frequency detecting element that can detect a temperature increase in an instant due to high-frequency wave absorption using semiconducting ceramic with positive resistance-temperature characteristics. The ceramic is composed mainly of barium titanate. A high-frequency heater incorporating the high-frequency detecting element is also disclosed. In the high-frequency detecting element, electrodes are provided on one main surface of semiconducting ceramic 1 with positive resistance-temperature characteristics and leads 3a and 3b are soldered to the electrodes 2a and 2b.

## Claims

### Claim 1

A high-frequency detecting element comprising:
semiconducting ceramic with positive resistance-temperature characteristics and having a thickness between 1 mm and 4 mm; and
not more than two electrodes, which are provided adjacently on said semiconducting ceramic.

### Claim 2 (depends on 1)

The high-frequency detecting element according to claim 1, wherein said semiconducting ceramic includes barium titanate.

### Claim 3 (depends on 1)

The high-frequency detecting element according to claim 1, wherein said semiconducting ceramic has a Curie point of 150° C. or less.

### Claim 4 (depends on 2)

The high-frequency detecting element according to claim 2, wherein said semiconducting ceramic has a Curie point of 150° C. or less.

### Claim 5 (depends on 1)

The high-frequency detecting element according to claim 1, wherein said not more than two electrodes consist of two electrodes located on one main surface of said semiconducting ceramic.

### Claim 6 (depends on 5)

The high-frequency detecting element according to claim 5, further comprising:
a frequency receiving surface of said semiconductor ceramic, said frequency-receiving surface not having electrodes formed thereon.

### Claim 7 (depends on 6)

The high-frequency detecting element according to claim 6, wherein high-frequency waves received on said frequency receiving surface cause a change in resistance of said semiconducting ceramic.

### Claim 8

A high-frequency detecting element for detecting a signal from a high frequency generating means, the high-frequency detecting element comprising:
a semiconducting ceramic with positive resistance-temperature characteristics, said semiconducting ceramic having a high frequency receiving surface positioned relative to the high frequency generating means to receive the signal of the high frequency generating means; and
two electrodes electrically bonded to an other surface of said semiconducting ceramic, said other surface not receiving the signal of the high frequency generating means;
wherein a resistance of said semiconducting ceramic measured between the two electrodes changes in response to changes in the signal.

### Claim 9 (depends on 8)

The high-frequency detecting element according to claim 8, wherein no more than said two electrodes are electrically bonded to said other surface of said semiconducting ceramic.

### Claim 10 (depends on 8)

The high-frequency detecting element according to claim 8, wherein water vapor in a signal path between the high frequency generating means and the high frequency receiving surface of said semiconducting ceramic is a cause of said changes in the signal.