Modular transceiver with adjustable specular member

• US 4,687,924 A
• Filed: 05/08/1985
• Issued: 08/18/1987
• Est. Priority Date: 05/08/1985
• Status: Expired due to Fees

• Current Assignee: ADT Diversified Services Inc (Johnson Controls International plc)
• Original Assignee: ADT Holdings Incorporated (Apollo Global Management, Inc.)
• Inventors: Leff, Kenneth J., Galvin, Aaron A., Giffone, Ralph A., Mason, Douglas L., Schide, John N.
• Primary Examiner(s): Westin, Edward P.
• Application Number:
  US06/731,918
• Time in Patent Office: 832 Days
• Field of Search: 250/216, 250/221, 250/239, 250/222.1, 250/223 R, 250/234, 250/235, 250/573, 250/574
• US Class Current: 250/216
• CPC Class Codes: G08B 17/103 using a light emitting and receiving device
• CPC Class Codes: G08B 17/113 Constructional details
• CPC Class Codes: G08B 29/145 of fire detection circuits

Abstract

A modular transceiver head including cooperative cover and base members operable as a transmitter or as a receiver of infrared energy. The cover member includes a window defining a comparatively wide field of view in azimuth and in elevation. An optical train including a gimbaled specular member that is mounted to the base member readily allows both rough and fine adjustment of the pointing direction of the specular member anywhere within the field of view of the cover member window. A controller including a processor is coupled to a transceiver head pair respectively operative as a transmitter and as a receiver of infrared energy to controllably project a beam of infrared energy therebetween through a protected region. The controller is operative to de-sensitize the beam against potential electrically interfering effects present along the beam path. The controller is periodically operative in a self-test mode to reduce the intensity of the projected-beam to simulate a smoke condition. The controller is periodically operative in a self-compensation mode to compensate for long and short term beam degradation effects such as pollution variation normally encountered along the beam path arising in the normal operation of the protected region and to compensate for film build-up on the elements of the transceiver head optical trains. The controller is cooperative with a watch-dog timer to monitor its own operating state. Plural alarm thresholds are operator selectable to provide enhanced confidence detection, and particularized signal indications are provided to readily and quickly identify possible alarm and trouble conditions.

Claims

1. A modular transceiver head for a projected-beam smoke detector, comprising:

a cover member having an infrared transparent window that subtends a preselected field of view in azimuth and in elevation;

a base member;

means for mounting said cover member to said base member in an air-tight sealing relation;

an optically active element disposed on a printed circuit board;

means including spaced walls integral with said base member having confronting slots for removeably mounting said optically active element to said base member such that said board slidably fits into and out of said confronting slots thereof;

means coupled to said walls for releaseably retaining said printed circuit board in said slots whereby different cards selected to provide either a transmitter or a receiver function are releaseably retained in the same slots;

an optically passive element having a focal length;

means for mounting said optically passive element to said base member in a preselected location selected such that said optically active element is positioned at the focal point of said optically passive element;

a specular member defining a pointing direction; and

means for mounting said specular member to said base member for a controlled movement relative to said base member in such a way that said pointing direction thereof is orientable to any selected position within said field of view of said window of said cover member;

said specular member mounting means including rough pointing direction control means for quickly and easily manually moving the specular member over comparatively large degrees of arc whereby initial pointing direction installation in the field is expedited;

said specular member mounting means including fine pointing direction control means cooperative with the rough pointing direction control means and including an azimuthal control thumbwheel and an elevational control thumbwheel and a mechanical linkage coupling said thumbwheels to said specular member cooperative with the coarse pointing direction control means to provide comparatively fine pointing adjustment of the pointing direction of the specular member in azimuth and in elevation by manually turning the corresponding azimuthal control thumbwheel and the elevational control thumbwheel.

2. The transceiver head of claim 1, wherein said window includes three sub-windows substantially at right angles to each other.

3. The modular transceiver head of claim 2, wherein said three sub-windows accomodate a 180°

field of view in azimuth and at least a 60°

field of view in elevation.

4. The modular transceiver head of claim 1, wherein said cover member mounting means includes a resilient seal positioned peripherally along the interface defined between said cover and said base members.

5. The modular transceiver head of claim 1, wherein said optically active element is one of an infrared emitting source and an infrared responsive detector.

6. The modular transceiver head of claim 1, wherein said specular member includes a mirror.

7. The modular transceiver head of claim 6, wherein said mirror mounting means includes a gimbal mounted to said base member.

8. The modular transceiver head of claim 7, wherein said gimbal includes means for providing a rough orientation of said pointing direction of said mirror within said field of view of said window of said cover member and means for providing a fine orientation of the pointing direction of the mirror within the field of view of said windows of said cover member.

9. The modular transceiver head of claim 8, wherein said rough adjustment providing means includes means for mounting said mirror for rotation with a shaft journaled in an upstanding wall provided therefor integral with said base member.