Patent GB-1320359-A (GB)
Title: Lift control systems
IPC: B66B1/16
Filed: 1970-11-03
Abstract: 1320359 Control of lift car EXPRESS LIFT CO Ltd 3 Nov 1970 52146/70 Heading B8L [Also in Division H3] A set of three input data selectors, of which one only, C is shown, have as inputs sets of buttons corresponding to the "up", or "down" buttons at each landing, and the buttons in the lift respectively, the inputs C1 being scanned cyclically in synchronism with the cyclical count of counter A whose cycle time is much less than the interfloor travel time of the lift car to pass the input information to a matrix-form memory D, E, F. The count of the counter J corresponds to the lift position, or a position slightly ahead of the lift in the direction of travel, and the count is changed by sets of sensing elements spaced in the lift shaft and mounted on the car, two per landing, the binary digit a being 0 when the lift is at a landing.  Operation of the lift car.-A comparator H receives as inputs the binary digits b-e of counter J and the count of A, giving for each count of A an output at one of terminals H1, H2 or H3, in dependence on the relative magnitudes of counts A and J. The state of memory unit D is also scanned in synchronism with the count of A, and, when the count corresponds to a landing that has been called, NAND gates 11-13 are enabled, communicating to one of gates 14-16 an output control to the lift drive system, the lift moving up or down respectively if the desired landing, corresponding to the instantaneous value of A when gates 11-13 are opened is higher or lower than the lift position. The landings served by the lift are divided into two groups, corresponding to the value of the most significant binary digit of J, the AND gates 8, 10 and the combination of NOR gate 17 and AND gate 9 ensuring that the operation of the lift via gates 11-13 is blocked when the digit f is unity. The gates 19-21, 22-27 represent part of the control system for the other group of landings, being enabled when f is unity, and utilizing, for example, a further comparator such as H, with outputs K1, K2, K3. There may be more than two groups of landings. The arrival of the lift at a desired landing, causes, via Inhibit multiplex G, and AND gate 4, the cancellation of the corresponding call in the memory unit D, also in synchronism with the count of A. If calls are received for landings above, and below the lift position, one set of calls is initially ignored. The scan decoder L indicates the count of A, and its outputs can be combined with the inputs C1 to light indicator lamps when a call is mad-. Strobe sequence circuit B.-The circuit comprises AND gates B1, B2, and NAND gates B3-B5 connected in a ring, the circuit operating in an oscillating mode to advance the count of A each time the output of gate B5 goes to unity, and to ensure, via further sets of logic gates 3-6, that the functions of reading, writing, and cancelling in the memory unit D, and the delivery of output pulses from one of gates 14-16 occur only at appropriate instants within the interval of time that the count of A has a given value. The waveforms are displayed in Fig. 3 (not shown). The control system may be realised with solid state circuits, and the outputs from 14-16 are fed to other equipment via pulse lengtheners (not shown). ).