Patent GB-1515338-A (GB)
Title: Elevator system
IPC: B66B1/18
Filed: 1975-09-01
Abstract: 1515338 Multi car elevator system WESTINGHOUSE ELECTRIC CORP 1 Sept 1975 [4 Sept 1974]  35904/75 Heading G3N A multi car elevator system 10 is controlled e.g. by a microprocessor system 70. The disclosure is the same as in Specifications 1515339 and 1515340 The elevator system 10 has cars 12 (only one of which is shown) and car controls 14, 16, 18, 20 (only four of which are shown), each car control having a car call control, a floor selector and an interface 28, 34, 40, 46. The latter connect to the interface 72 of the microprocessor 70. Car calls are registered on array 60 in each car and hall calls are registered using push buttons 62, 64, 66, the complete system being synchronized by clock timing 78. Successive like time intervals are divided into equal time intervals called scan slots, each floor of the building being assigned to a different scan slot, each floor having two slots one for the up and one for the down direction. When a slot is assigned to a car by supervisory control processor 70 the car can see a hall call from the floor associated with that slot. Read only memories in each car control provide signals for the supervisory control indicating which floors, and service directions therefrom, each car is enabled to serve hall calls from. The supervisory control uses these signals to divide the floors and service directions therefrom, i.e. scan slots, into sets, each set being served by the same combination of cars. The sets are constant until a car or floor enters or leaves service when the sets are redefined. Then the supervisory control determines the average number of scan slots A SB  in the building per in service car and the average number of scan slots A SI  within each set per in service car capable of serving the set. To assign scan slots associated with floors served by more than one car, the supervisor determines the average A CB  of registered calls per in service car and the average number of hall calls per car for each set A CI  and assigns a scan direction to each car. If the car is busy, the assigned scan direction is the same as the car travel direction. If the traffic is normal, the cars are arranged with half the cars going each way but this can be changed to deal with up and down peak conditions. To update scan slot assignments, the previous assignment table for each car is cleared except those scan slots and served by only one car and selection then occurs. Thus the calls are equally distributed among the elevator calls. The interfaces 28, 34, 40, 46 each have a serially accessed memory intermittently receiving command words from the processor. The memory repetitively reads out the commands to the car controller and updates them in response to a new word without interrupting the data flow to the controller. Each interface has internal logic and timing to control its serially accessed memory to reduce the memory and processing speed requirements of the processor 70. This is claimed in Specification 1515339. Various other features are described in great detail e.g. the processor 70 Fig. 4 (not shown), the interfaces Figs. 8A and 8B (not shown), the computer programs, Figs. 10-23 (not shown) and the assignment of scan slots, Fig. 24 (not shown). Main floor and convention floor features 74, 76 may also be provided.