Patent GB-734471-A (GB)
Title: Door control mechanism
IPC: B66B13/26
Filed: 1953-11-04
Abstract: 734,471. Door operating. OTIS ELEVATOR CO. Nov. 4, 1953 [Nov. 13, 1952]. No. 30455/53. Class 65(1). [Also in Groups XXXVI and XXXVII] A closure for use in lifts carries means to detect the proximity of objects, together with means for compensating for the action of the detecting means in respect of objects' belonging to the lift installation; the presence of a person , is thus detected, without response to the adjacent cage or shaft door or gate or to variations in the relationship of, for example, the cage and shaft structure. In the apparatus described, the detecting means controls automaticallyacting doors to stop or reverse their closing movement if a person should be in the doorway, and the detecting means comprises an antenna on the door connected to an electron tube which is affected by changes in the capacity between the antenna and any adjacent earthed object. The door-operating mechanism shown in Fig. 1 comprises an arm 22 actuated by a geared electric motor 18 on the cage and connected by a link 25 to the hanger 23 of the cage door 16. The hanger 23 carries a fixed member 30 and a member 31 which is mounted on links 32, these two members receiving between them a roller 35 on the shaft door, so that the two doors move together ; the member 31 has a roller 33 for engagement with a fixed cam 34 when the doors are closed, to give clearance space between the members 30, 31, and allow the latter member to fall and take up the clearance when the doors move from the closed position. A spring 44 ensures final closing of the doors. The circuits of the motor are controlled by position switches which connect or by-pass resistances to slow down the motor at about mid-stroke of the doors and again on approaching the extreme positions (see Group XXXVII) ; the closing circuit includes additional resistance so that closing is slower than opening. The door closes automatically after remaining open for a predetermined interval. If the detector is affected during closing, the motor circuit is opened and the motor is braked by connection to a rectifier, and the door is then slowly opened ; it remains open until the detector becomes unaffected or the normal interval (or, in a modification, a shorter interval) elapses, whichever is later. The detector comprises an antenna 53 mounted at the edge of the door and so arranged and shielded as to be affected by objects in the doorway or close outside it, and the compensating means includes two small antennae 54, 55 similarly arranged. Each antenna is connected to an electron tube placed at its upper end, and these tubes are so interconnected, and associated impedances adjusted, that the presence of any object near one antenna and not the others will produce a resultant current to energise a responsive relay (see Group XXXVI). Any changes in relative position between the cage door and the shaft door or cage or shaft structure will affect all the antenna equally and produce no result, and tilting of the cage will affect the antennae 54, 55 equally and oppositely so that their combined effect will not be altered. A person will, however, affect antenna 53 most or only, or may place a hand to affect one of the other antennae only, so that his presence will be detected.