GB1468910A - Control arrangements for power operated sliding doors - Google Patents

Abstract

1468910 Automatic controls for powered sliding doors EXPRESS LIFT CO Ltd 21 May 1975 [21 May 1974] 22681/74 Heading E2M A power operated sliding door arrangement has means which detects an object within a predetermined distance from the door and produces an output signal to stop or reverse the door, a control element for varying the sensitivity of the detecting means means producing a reference signal when the door approaches to a distance from a reference member, and means to actuate said control element in dependence on the time interval between the generation of the reference signal and the output signal from the detecting means when the reference member is detected, the sensitivity of the detecting means being thereby maintained constant. Two sliding lift doors 1, 2, Fig. 1, are operated by an electric motor (within casing 6) and plastics edge members 15, 33 each house two parallel conductors 34 which form part of a capacitive detector means including a detector circuit 36, Fig. 5, and variable capacitor 35 by which the sensitivity of the circuit is adjusted. The output from circuit 36 produced when an object is within a predetermined distance i.e. 6 inches from a door edge changes the capacitance between the conductors 34 and a relay 37 is actuated which stops or reverses the lift doors. When the doors come within 8 inches of each other (the reference member in this case being the other door) a microswitch (46, Fig. 3, not shown) in door 1 is actuated by a cam (47) to open contact 46A and isolate the relay 37. At the same time a reference signal from the microswitch opens a contact 46B which triggers a monostable circuit 38, the trailing edge of the pulse from which triggers a further monostable circuit 39. When the detector on door 1 detects the other door the output signal from 36 is fed to the outputs of monostable circuits 38 and 39. Comparison is made between the relative times of arrival of the signal from 36 at the respective circuits 38, 39 and an output, indicative of the departure of the sensitivity of the detector from the preset level, is fed, via a circuit 43, to a motor actuating a gear box 45 which applies corrective adjustment to capacitor 35. The sensitivity is preset by adjustment of the pulse length of circuit 38; the required sensitivity occurring when the arrival of the signal from 36 coincides with the trailing edge of the pulse from 38. The edge members 15, 33 are in addition sensitive edge devices which stop or reverse the door on contacting an obstacle. In single door arrangements the reference member can be the door frame which the door approaches on closing. Reference has been directed by the comptroller to Specifications 1227197 and 1227198.