Patent GB-1221958-A (GB)
Title: Electric system for controlling a gas discharge lamp and a lamp housing shutter
IPC: H05B41/231
Filed: 1968-07-22
Abstract: 1,221,958. Control systems for gas discharge lamps; control of A.C. motors. BERKEY PHOTO Inc. 22 July, 1968 [25 July, 1967], No. 34858/68. Headings H2H and H2J. A gas discharge lamp 31 for photographic exposure is housed in a lamp housing 114 with a shutter 115 and a blower 66. When the apparatus is first switched on with the shutter 115 closed, lamp 31 is run at full power for one minute to rapidly warm it up then reduced to low power and the blower motor started at reduced power. When the exposure is to be made a switch 112 is operated which automatically opens shutter 115 and energizes lamp 31 to full power. At the end of an exposure the shutter 115 is closed, lamp 31 is reduced in power, the blower continues in operation at reduced power so that the apparatus is ready for another exposure. When the lamp is turned off the blower motor is operated at full power for one minute to rapidly cool lamp 31. Initially switch 19 is closed to energize relay coil 17 to close contacts 14 which applies the supply to primary 25 of auto-transformer 24. This completes the supply through lead 44, resistor 46 and normally closed switch 47 to diode 49 and coil 54 and back to the other side of the supply through leads 45 and 87. Diode 49, coil 54 and capacitor 52 are connected by leads 50, 51  across the primary 39 of starting transformer 36 and provide pulses through the secondary 40 and capacitor 41 to ignite discharge tube 31. Simultaneously a supply is provided from tapping 27 on primary 25 of autotransformer 24 through lead 90 and normally closed contacts 106, 104 on relay 77 to coil 102 of relay 101 to close switch 100 which applies full power to lamp 31. Simultaneously from tapping 27 through lead 90 coil 79 of relay 77 is energized with return lead 87 and through lead 89 coil 55 of relay 56 is energized with return lead 45 and 87. Relay 56 is time delayed and after 2 or 3 seconds it closes opening contact 47 to cut out the starting circuit comprising diode 49, coil 54 and capacitor 52. Relay 77 is also time delayed and after one minute it changes contact 104 over to 107 thereby de-energizing relay 101 and opening switch 100 thereby reducing the power to lamp 31 and also changes over contact 74 to 76 thereby energizing blower motor 65 from tapping 29 on primary 25 of autotransformer 24 with return lead 72 thereby operating the blower on reduced power. When an exposure is to be started switch 112 is closed which completes the supply from tapping 27 and lead 90 through lead 111 and contacts 107, 104 to relay 101 to again close contact 100 thereby applying ful power to lamp 31 and also energizes coil 109 of relay 110. This completes the supply from tapping 27 and lead 90 through relay 110 to motor winding 120 and brake coil 122 lifting off the brake and energizing motor 119 so that it opens shutter 115 until top limit switch 124 on the lamp housing is opened by arm 126 on the shutter when the motor is stopped and the brake applied by de-energizing coils 120, 122. When the exposure is over, switch 112 is opened which drops out relay 101 thereby opening contact 100 to reduce the power to lamp 31 and drops out relay 110 thereby reversing the motor to close shutter 115. When switch 19 is opened to drop out relay 17 to switch off lamp 31, a circuit is completed from supply terminal 10 through lead 85, contacts 19, 84, contact 80, contacts 75, 74 to blower motor 65 with return through lead 72 and fuse 22 so that full voltage is applied to the blower motor 65 which therefore runs at full power to rapidly cool the lamp. Contact 80 was closed by relay 81 when main contacts 14 were closed. When contacts 14 are opened relay 81 is held closed for one minute by the discharge of capacitor 94 through the relay coil 82 then relay 81 is dropped out opening contact 80 and switching off blower motor 65.