Pyroelectric infrared detector

• US 4,825,079 A
• Filed: 05/28/1987
• Issued: 04/25/1989
• Est. Priority Date: 05/30/1986
• Status: Expired due to Term

• Current Assignee: Sumitomo Metal Mining Company Limited
• Original Assignee: Sumitomo Metal Corporation (Nippon Steel Corporation)
• Inventors: Takahashi, Hideki, Takamatsu, Keiji
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/055,122
• Time in Patent Office: 698 Days
• Field of Search: 250/338 PY, 250/338 R, 250/342
• US Class Current: 250/338.3
• CPC Class Codes: G01J 5/34 using capacitors, e.g. pyroelectric capacitors
• CPC Class Codes: G01J 5/35 Electrical features thereof

Abstract

A pyroelectric infrared detector for use in, for example, an intrusion alarming system has a pyroelectric element, a FET for picking up the output of the pyroelectric element, a capacitor connected in parallel to the pyroelectric element, and other circuit parts. These constituent parts are integrally packed in a package.

Claims

1. A pyroelectric infrared detector, comprising a pyroelectric element and a FET for picking up the output of said pyroelectric element, a capacitor connected in parallel to said pyroelectric element, and a package in which at least said pyroelectric element and said capacitor are accommodated integrally.

2. A pyroelectric infrared detector according to claim 1, wherein said package is a TO-5 metal package.

3. A pyroelectric infrared detector according to claim 1, wherein said package is a plastic package.

4. A pyroelectric infrared detector according to claim 1, further comprising a leak resistor.

5. A pyroelectric infrared detector according to claim 1, wherein said capacitor has a dielectric loss not greater than 0.01 as measured at 100 Hz and at room temperature.

6. A pyroelectric infrared detector according to claim 1, wherein said capacitor is a chip-type capacitor.

7. A pyroelectric infrared detector according to claim 1, wherein the dielectric material of said capacitor is at least one of mica and ceramics.

8. A pyroelectric infrared detector according to claim 1, wherein the capacitance C₂ of said capacitor is determined by the following formula:

space="preserve" listing-type="equation">C.sub.2 =C-C.sub.1

where C represents the equivalent input capacitance of the detector, while C₁ represents the capacitance of said pyroelectric element.