Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1990-03-22
1991-08-20
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
187 56, G01V 904
Patent
active
RE0336688
ABSTRACT:
In the entranceway between an elevator car and a floor are two oppositely sliding doors. The approach of these doors is controlled by a detection system that senses the presence of objects between the doors. This system includes, on each door, a plurality of emitters which are vertically spaced apart the door edge, for radiating noncollimated light towards the edge of the other door. At the top and bottom portions of each door edge there is a sensor which can receive the radiation from the emitters on the other door edge. The emitters on each door edge are sequentially turned on and the sensors on the opposite door edge provide a corresponding signal as they are turned on, unless an obstruction is in the way, causing the detection system to generate a signal that thus indicates than an object is between the doors.
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patent: 3805061 (1974-04-01), Dimissimy et al.
patent: 3805064 (1974-04-01), Kornylak
patent: 3825745 (1974-07-01), Thomson
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patent: 4063085 (1977-12-01), Montanvert
patent: 4247767 (1981-02-01), O'Brien et al.
patent: 4266124 (1981-05-01), Weber et al.
Jones William W.
Nelms David C.
Otis Elevator Company
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