Patent GB-1220815-A (GB)
Title: Stage lighting control units
IPC: H05B37/02
Filed: 1967-05-03
Abstract: 1,220,815. Programmed control of stage lighting. STRAND ELECTRIC & ENG. CO. Ltd., F.P. BENTHAM and P.R. SHERIDAN. April 26, 1968 [May 3, 1967], No.20462/67. Addition to 1, 083, 408. Heading G3N. A stage lighting control system as disclosed in parent Specification wherein in addition to the two individual active memory elements the active memory includes a backing store connected to transmit information to and from the memory store and the active memory elements are connectible to the backing store solely for the reception of information therein. As shown, Fig. 1B dimmer control signals on lines 1, 2 are fed to a plurality of dimmer potentiometers such as 7. The output of each potentiometer passes through an AND gate 8, an OR gate 9 and a line 10 to a channel of a dimmer bank 11, Fig. 1A. The gate 8, Fig. 1B, is controlled by a bi-stable trigger 12 enabled by channel or master switches, a red light 14, located within the scale of the potentiometer 7 being energized when gate 8 is inhibited. Each dimmer line 10 Fig. 1A is also connected to a level meter, not shown, through an AND gate 16 and lines 17. Each dimmer line 10 is connected by a line 19a-19w to a corresponding stage of a shift register 20 and stage of which can be connected through a gate 29a-29n to a comparator 31 for comparison with the count in a binary counter 32, changed to an analogue value by a digital-to-analogue converter 33. The count in counter 32 is decremented, from a maximum light value, by pulses from a generator 139 through a gate 140 until the signal from the converter 33 falls below that from the shift register stage. The comparator then issues a signal to a pulse generator 146, such that a pulse from an output IV, through an AND gate 48a instructs a backing store element 50a to copy the count in the counter 32. The pulse generator 146 then sets counter 32 to the full light value and steps the shift register to stage 20b. This continues until all backing stores 50a-50n are filled in dependence on dimmer settings. The contents of the backing stores 50, Fig. 1B, are then stored in a memory store 55, or, used directly. The contents of the stores are transferred via parallel-connected AND gates 58A, 58B to binary stores 59A, 59B the outputs of which are fed through resistive digital-to-analogue converters 60A, 60B to a channel integrator 61. Master control circuits 62A, 62B control the integrator so that the output of the integrator is fed by the store 59A, 59B whose master control is set the higher. The actual output is the analogue value of the selected store multiplied by the percentage setting of the corresponding master control. The occupation of a store 59A, 59B is indicated by a white lamp 63. With cross-fading the limits are the values set in stores 59A, 59B. The output of the channel integrator 61 is fed to the OR gate 9 so that in dependence on the state of the bi-stable trigger 12 either the voltage at slider 7 is fed to the corresponding dimmer line 10 or the contents of stores 59A, 59B. The circuit thus enables dimmer signals to be recorded in the memory 55 and re-presented on lines 10 to control the stage lighting accordingly. The circuit is controlled by a clock, Fig. lc (not shown), whereby the contents of the backing stores 50 can be transferred to the memory store 55 to build up a lighting plot consisting of as many different lighting cues as the memory contains channels. Re-call is also controlled by the clock as is modification of a recorded effect.