Patent GB-1171916-A (GB)
Title: Improvements in Lighting Systems.
Inventor: ISAACS ANTHONY LEONARD
IPC: H05B37/02
Filed: 1966-10-21
Abstract: 1,171,916. Lighting control systems. THORN ELECTRONICS Ltd. 20 Oct., 1967 [21 Oct., 1966], No. 47344/66. Heading H2H. [Also in Division G3] A lighting control system generally similar to that described in co-pending Specification 1,171,915 is provided with means for filing predetermined lighting plots and for automatically changing from one plot to another at a uniform rate proportional to the change of brightness required. As shown, the members 14, 18, 19, 31 of the basic (studio) system are duplicated to form a preset circuit comprising members 14<SP>1</SP>, 181, 19<SP>1</SP>, 31<SP>1</SP> and partially duplicated to form a fader circuit comprising members 14<SP>11</SP>, 18<SP>11</SP>, 19<SP>11</SP>, the preset and studio stores being interconnected with a file buffer store 34 and a filed core store 33 controlled by a push-button operated file selector 35. During rehearsal lighting plots are set up on selected lighting channels by operation of the faders 5... 9 and are filed. In production the first plot is read into stores 14, 14<SP>11</SP> and the second plot read into preset store 14<SP>1</SP>. A differential comparator 36 produces an analogue output proportional in any lighting channel period to the difference between the outputs of the preset and fader brightness counts registered in the stores 18<SP>1</SP>, 18<SP>11</SP>. According to the sign of the difference the analogue output of comparator 36 is passed to a " fade up " gate 40 or a " fade down " gate 42 respectively controlled by a "fade up" push button 41 and a differential comparator 39 and by a " fade down " push-button 44 and a differential comparator 43, the comparators 39, 43 producing an enabling output in the period of any channel when a difference exists between the studio and preset brightness counts. Thus when a difference exists and the appropriate button 41, 44 is actuated, an analogue signal proportional to the difference is passed to the studio voltage controlled generator 25 which changes the lamp brightness and the brightness count in the studio store 14 at a proportional rate until no difference exists and the enabling signal from comparator 39 or 43 disappears. All channels change brightness in substantially the same time (over a number of cycles of all the channels) regardless of the magnitude of the change. A cross-fade between two plots necessitating both brightening and dimming is made by operating a push-button 45 controlling both gates 40, 42. Independent control of " fade-up" " and " fadedown" " times can be obtained by replacing the V.C.G. 25 by a "raise" V.C.G. and a " dim " V.C.G. whose outputs are coupled to the unit 31 and which are respectively controlled by additional V.C.G's in the connection (not shown) between the divider 16 and the controlled V.C.G. The voltage applied to the additional V.C.G's controls the pulse rate of pulses reaching the "raise" " and " dim " V.C.G's. Two channels may be allocated to control the "raise" and "dim" times for the lighting plots. If the analogue outputs from the scanner 21 for these channels are used as the control voltages for the additional V.C.Gs, determining the "fade-up" and "fade-down" times, the counts stored by the cores allotted to these channels become digital encodements of the selected fade times and may be filed with one of the relevant lighting plots.