AUTOMATIC DOOR-OPENING SYSTEM USING AN ACOUSTIC OBJECT DETECTION SYSTEM

• US 3,742,434 A
• Filed: 09/30/1971
• Issued: 06/26/1973
• Est. Priority Date: 09/30/1971
• Status: Expired due to Term

• Current Assignee: Delbert E. Marker, Warren L. Leyde
• Original Assignee: Delbert E. Marker, Warren L. Leyde
• Inventors: Leyde, Warren L., Marker, Delbert E.
• Primary Examiner(s): Farley, Richard A.
• Application Number:
  US05/185,073
• Time in Patent Office: 635 Days
• Field of Search: 49/25,31 340/1R,261,1T,16C
• US Class Current: 49/25
• CPC Class Codes: E05F 15/73 responsive to movement or presence of persons or objects
• CPC Class Codes: E05F 2015/763 using acoustical sensors
• CPC Class Codes: E05Y 2900/132 Doors
• CPC Class Codes: G01S 13/18 wherein range gates are used
• CPC Class Codes: G01S 15/18 wherein range gates are used

Abstract

An object detection system is disclosed which makes use of an acoustic transducer for generating compressional waves in the air and detecting return pulses from an object lying within the detection zone. A transducer mounting system includes a transducer slug mounted for generating acoustic waves from both ends of the slug. The antenna system includes a reflector housing adapted to accommodate variable surfaces for controlling the energy pattern. Details of the electronic circuitry associated with the transducer mounting system and a door opening system are disclosed.

Claims

1. A system for automatically controlling the operation of one or more doors, comprising an ultrasonic transducer means for transmitting and receiving ultrasonic waves within a predetermined detection zone, means supporting said transducer means in proximity to a door so that individuals desiring to pass through said door first enter said detection zone, clock means developing relatively low frequency clock pulses, an ultrasonic source controlled by said clock means to produce a burst of ultrasonic energy for each of said clock pulses, means coupling said source to said transducer, a detection circuit also coupled to said transducer and providing an output signal representing pulse returns from objects within said detection zone, said detection circuit comprising an amplifier, an automatic gain control circuit regulating the gain of said detection circuit and an integrating means coupled to the output of said detection circuit for controlling said automatic gain control circuit in response to the magnitude of said output signal, the time constant of said integrating means being chosen to be longer than the expected duration of return pulses from individuals within said detection zone, means coupled to said output signal for discriminating against false pulse returns, said disciminating means providing a control signal only when said returns are characteristic of an object within said detection zone, and means controlling the opening or closing of said door in response to said control signal.

2. A door-controlling system as recited in claim 1, wherein said discriminating means includes a normally-opened switch having said output signal connected thereto, a range gate circuit controlled by said clock pulses closing said switch for a predetermined time period subsequent to each of said clock pulses to thereby block close-in and floor return pulses, a logic circuit having connected thereto the output of said switch, and a source of a threshold signal coupled to said logic circuit, said logic circuit being operative to provide said control signal only if said output signal exceeds said threshold signal on two out of three successive cycles determined by said clock pulses.

3. A door-controlling system as recited in claim 1, wherein said detection circuit comprises means regulating the components of said output signal corresponding to noise at a predetermined, substantially constant level, and wherein said disciminating means includes a source of a threshold signal, the magnitude thereof being greater than that of the regulated noise components in said output signal, and a threshold detector coupled to said threshold signal source which is normally operative to inhibit said output signal except when the level thereof exceeds that of said source.

4. A door-controlling system as recited in claim 1, wherein said control means comprises an electrical door actuator, a source of power, a control device in circuit with said source and said actuator, and means energizing said control device for a relatively long period of time in response to said control signal.

5. A door-controlling system as recited in claim 4, wherein said control device comprises a bidirectional controllable semiconductor.

6. A door-controlling system as recited in claim 1, wherein said ultrasonic transducer means comprises a reflector housing defining an interior cavity and an aperture for the passage of ultrasonic waves, and a single transducer slug supported within said cavity.

7. A door-controlling system as recited in claim 1, wherein said ultrasonic energy has a frequency of 75 kHz and said clock source has a frequency of 15 Hz.