Infrared-type intrusion detector

• US 4,551,711 A
• Filed: 01/30/1984
• Issued: 11/05/1985
• Est. Priority Date: 08/26/1983
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited 1006 OAZA Kadoma-Shi Osaka Japan
• Original Assignee: Asahi Matsushita Electric Works Ltd. (Panasonic Holdings Corporation)
• Inventors: Kondo, Mikio, Akiyama, Shoichi
• Primary Examiner(s): Rowland, James L.
• Assistant Examiner(s): Tumm, Brian R.
• Application Number:
  US06/575,405
• Time in Patent Office: 645 Days
• Field of Search: 340/565, 340/567, 250/342, 250/353
• US Class Current: 340/567
• CPC Class Codes: G08B 13/19 using infrared-radiation detection systems G08B13/194 takes precedence
• CPC Class Codes: G08B 13/193 using focusing means
• CPC Class Codes: Y10S 250/01 Passive intrusion detectors

Abstract

An infrared-type intrusion detector for monitoring the presence of a person is disclosed. The detector has a plurality of concave reflector segments for defining separate fields of view. Infrared radiation emanating from the person in any of the fields of view is collected and focused upon a single sensing element to produce a cautionary signal representative of such detection. Plane mirrors are introduced in an optical reflection system of the detector to reflect the radiation from the reflector segments upon the sensing element, such as to reduce the spacing or dimension required for the optical system along the optical axis of the sensing element, whereby the detector is allowed to be made compact in size. Further, the optical system of the detector includes a device for selectively interrupting one or more paths between the respective reflector segments and the sensing element, such that the detector can receive the infrared radiation only from the selected or desired fields of view and ignore it from the undesired fields depending upon certain operating conditions, enhancing detection reliability.

Claims

1. An infrared-type intrusion detector comprising:

a housing with at least one front opening and an inner bottom surface;

a single infrared sensing element disposed on the side of said inner bottom surface with its optical axis extending fore and aft of the housing;

a plurality of concave reflector segments disposed on the bottom surface of the housing for providing separate fields of view and collecting infrared radiation therefrom through said front opening;

plane mirror means disposed forwardly of the concave reflector segments within the housings for reflecting said infrared radiation once reflected from said concave reflector segments and focusing it upon said infrared sensing element;

electrical circuit means responding to the infrared detection by the sensing element to produce a cautionary signal; and

means for selectively interrupting one or more paths between the respective concave reflector segments and the sensing element, said means for selectively interrupting comprises an assembly of plane mirrors defining said plane mirror means, each plane mirror corresponding to each one of said concave reflector segments and being pivoted at its one end to a front cover of the housing so as to be movable between an operative position where it focuses the infrared radiation reflected from the corresponding concave reflector segment upon the sensing element and an interrupting position where it fails to focus the infrared radiation reflected from the corresponding concave reflector segment upon the sensing element.

2. An infrared-type intrusion detector as set forth in claim 1, wherein said front opening is provided with a louver for preventing the entrance of the rays of infrared radiation from the area other than said fields of view into the sensing element.

3. An infrared-type intrusion detector as set forth in claim 1, wherein said interrupting means further comprises a corresponding number of switch knobs, each of said switch knobs being connected to one of the plane mirrors to select the position thereof between said operation and interrupting positions.

4. An infrared-type intrusion detector as set forth in claim 1, further including a mounting base to which said housing is pivotally supported such that said housing can pivot about a pivot axis perpendicular to the optical axis of the sensing element and can be held at desired angular positions about that axis.

5. An infrared-type intrusion detector as set forth in claim 4, wherein said housing is further rotatably supported by said base about the optical axis such that it can be held at desired angular positions both about the pivot axis and the optical axis.

6. An infrared-type intrusion detector comprising:

a housing with first and second front openings orientated in different directions with each other and with inner bottom surface;

a single infrared sensing element disposed on the side of said inner bottom surface of the housing with its optical axis extending fore and aft of the housing;

a first reflecting row composed of a plurality of concave reflector segments disposed on the bottom surface of the housing in a row for providing first group of separate fields of view and collecting infrared radiation therefrom through said first opening;

a second reflecting row which is parallel to the first row and composed of a plurality of concave reflector segments disposed on the inner bottom surface of the housing in a row providing second group of separate fields of view and collecting infrared radiation therefrom through said second opening;

plane mirror means disposed forwardly of the concave reflector segments for reflecting the infrared radiation from each of said concave reflector segments upon said infrared sensing element, said plane mirror means comprising an assembly of a number of plane mirrors arranged in first and second rows, each plane mirror corresponding to one of said concave reflector segment and being pivoted at its one end to a front cover of the housing so as to be movable between an operative position where it focuses the infrared radiation reflected from the corresponding concave reflecting segment upon the sensing element and an interrupting position where it fails to focus the infrared radiation reflected from the corresponding concave reflector segment upon the sensing element; and

electrical circuit means responding to the infrared detection by the sensing element to produce a cautionary signal, said first and second rows of concave reflector segments being arranged on both sides of the sensing element.

7. An infrared-type intrusion detector as set forth in claim 6, wherein said plane mirror means further comprises a corresponding number of switch knobs each connected to one of the plane mirrors so as to select the position thereof between said operation and interrupting positions.

8. A infrared-type intrusion detector as set forth in claim 6, wherein said first and second front openings are provided respectively with louvers for preventing the entrance of the rays of infrared radiation from the area other than said fields of view into the sensing element.

9. An infrared-type intrusion detector as set forth in claim 6, further including a mounting base to which said housing is pivotally supported such that said housing can pivot about a pivot axis perpendicular to the optical axis of the sensing element and can be held at desired angular positions about the axis.

10. An infrared-type intrusion detector as set forth in claim 9, wherein said housing is further rotatably supported by said base about the optical axis such that it can be held at desired angular positions both about the pivot axis and the optical axis.