# US 5,352,895 A · Pyroelectric device

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- Number: US 5,352,895 A
- Document ID: US5352895A
- Status: Granted
- Kind: A
- Application number: 08/018,530
- Filed: 1993-02-17
- Granted: 1994-10-04
- Earliest claimed: 1992-02-19
- Assignees: Nohmi Bosai Ltd.
- Inventors: Masao Inoue
- Web page: https://patentgrep.com/patent/US5352895A

## CPC

- G01J 5/34: using capacitors, e.g. pyroelectric capacitors
- G08B 13/191: using pyroelectric sensor means
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)
- G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS

## Abstract

A pyroelectric device includes a pyroelectric member for detecting infrared radiation, a transistor whose gate electrode is connected to one of the terminals of the pyroelectric member, a drain terminal connected to a drain electrode of the transistor, a source terminal connected to a source electrode of the transistor, a grounding terminal connected to the other terminal of the pyroelectric member, and a gate resistor connected between the terminals of the pyroelectric member. The gate resistor used in a pyroelectric device for a fire detection has a resistance ranging from 5 to 50 gigaohms, and the gate resistor used in a pyroelectric device for an intrusion detection has a resistance equal to or less than 30 gigaohms.

## Claims

### Claim 1

A pyroelectric device for a fire detection, comprising:
a pyroelectric member made of polyvinylidene fluoride for detecting infrared radiation;
a transistor having a gate electrode connected to one terminal of said pyroelectric member;
a drain terminal connected to a drain electrode of said transistor;
a source terminal connected to a source electrode of said transistor;
a grounding terminal connected to another terminal of said pyroelectric member; and
a gate resistor connected between the terminals of said pyroelectric member, said gate resistor having a resistance of about 10 gigaohms.

### Claim 2 (depends on 1)

A pyroelectric device according to claim 1 wherein said transistor is a field-effect transistor.

### Claim 3 (depends on 1)

A pyroelectric device according to claim 1 further comprising a voltage-stabilizing capacitor connected to said drain terminal and said grounding terminal and having a capacitance of about 10 pF.

### Claim 4 (depends on 1)

A pyroelectric device according to claim 1 further comprising a noise-cutting capacitor connected between said source terminal and said grounding terminal and having a capacitance of about 10 pF.