Patent GB-1109005-A (GB)
Title: Traffic supervisory apparatus
IPC: B66B13/26
Filed: 1965-07-06
Abstract: 1,109,005. Detecting motion acoustically. WESTINGHOUSE ELECTRIC CORPORATION. 6 July, 1965 [30 July, 1964], No. 28584/65. Heading H4D. [Also in Division E2] Movement of load (e.g. a passenger) towards the entrance E (Fig. 2) of an elevator car is detected by means of an ultrasonic system including an assembly 3 comprising a transmitter ST and a receiver SR operating on the Doppler principle and utilized to prevent or interrupt closure of the doors. The assembly S is mounted on the roof of the car with the axes of ST and SR directed outwardly and downwardly (as per Fig. 3 or Fig. 10, not shown) so as to be responsive to a vertical component in the normal movement of an intending passenger approaching the car when the doors are open or have started to close whilst being unresponsive to movement parallel to the doors e.g. that of a person walking along the corridor parallel to the plane of the doors. The transmitter ST, comprising a ceramic transducer, forms the frequency controlling element (40,000 c.p.s.) for the driver transmitter 63 (Fig. 5A, not shown) some of the energy from the latter being coupled into the transformer T1 in the circuit of the receiver transducer SR which includes a limit switch AS operated by a cam ASC on the car doors to interrupt the circuit when the doors are closed. The signal produced in transformer T1 due to reflection of the ultrasonic waves by a moving passenger is then amplified in circuitry 65 including a cascode pair V 2 , V 3  feeding a section 67 selective only to frequencies above that of the transmitter so that a response is produced in respect only of passenger movement towards the doors. This results in a beat (Doppler) frequency of approximately 75 c.p.s. (for average passenger movement) and this frequency after amplification in section 67 (also Fig. 5 B, not shown) is detected in section 73 and amplified in V8 to control the supply of operating current to a relay AR via V9, V10 connected in a Schmitt trigger configuration. The coil of AR is connected in series with the TS1 contacts of a door-operated switch TS (operated together with switch AS by cam ASC) the contacts being closed when the door is open so that AR is energized causing contacts AR1 to open, these contacts, which are connected in series with the door-edge safety switches 49, A49 (also Fig. 8, not shown), opening the circuit to the door-safety relay OR which then operates via contacts DR1, DR2 to interrupt the supply current to the field 29F and armature 29A windings of the door operating motor 29. The latter operates in conventional manner via the linkages known in Fig. 2. Operation of relay OR also opens the circuit for the door closing relay CL and closes that of the door-opening relay OP (each connected in series with respective door-operated limit switches 87, 89) so that the doors are re-opened if they were in the closing cycle when the intending passage is detected. By constructing cam ASC to clear switch AS when the doors are fully closed the closure of contacts TS2 of door switch TS (contacts TS1 now being open) allows the system to control other unspecified functions via relay ARA (Fig. 5B) the response in this case being due to an ultrasonic path involving reflection from the inside surface of the doors. Operation in either mode is signalled by respective pilot lamps PL, PLA and a manually operated switch SW6 (Fig. 8) allows normal door opening and closing to be effected. Arrangements such as those of Fig. 3 and Fig. 10 may be combined to produce a broad detection field and a highly directional small area field. By employing a frequency of about 4 x 10<SP>5</SP> c.p.s. the high attenuation with distance allows the system to have a sensitivity which is inversely proportional to the distance of the passenger from the doors. The system may be made sensitive to particular ranges by pulsing the transmitter and suitably gating the receiving circuitry.