Patent GB-1322653-A (GB)
Title: Control circuit for an intelligence reproducing device such as an optical displayer
IPC: G03B31/00
Filed: 1971-07-23
Abstract: 1322653 Tape recordings; associated working DEJUR-AMSCO CORP 23 July 1971 [24 Sept 1970] 15508/72 Divided out of 1322651 Heading G5R [Also in Division G2] A control circuit, for an audio-visual display using a tape recorder 6 carrying a soundtrack and control signals, includes a device (viz. solenoid 82) for actuating the feed mechanism of the displayer (viz. a cine projector) by charging an energy store (capacitor 94) from an energy source 24 and then discharging it to power the device. Three modes of operation are permitted by switch 84. When the switch 84 is in the "TAPE " mode, source 24 charges capacitor 94 via closed relay contacts 60B. Then, in response to a signal recorded on the tape on recorder 6, the relay 60 is activated. This opens contacts 60B and closes contacts 60C thereby letting capacitor 94 discharge through solenoid 82 and hence permitting the film feed mechanism of the projector to be activated (details of this mechanism claimed in Specification 1,322,652. Cam 118 on shaft 120 which is connected to the feed mechanism breaks the circuit when the feed mechanism is in its return cycle. The mechanism is therefore halted until another signal to energize relay 60 is received. With switch 84 in the " RUN " mode, contacts 96, 128 are joined and the solenoid 82 continuously energized. The projector can then operate independently of the tape recorder 6.  When the switch 84 is in the " AUTO " mode, contacts 126, 132 ,110, 138 being joined, the circuit enclosed by the intermittent lines is energized. Manual variation of resistance 150 varies the conducting of transistor 144 and hence the energization of the relay 140. The relay 140 and its contacts 140A, 140B operate in the same way as the relay 60 and its contacts 60B, 60C. Thus variation of the resistance 150 provides speed control for the projector. To start-up the apparatus in the " TAPE " mode, the projector is automatically threaded whilst the recorder 6 is held inactive by open contacts 38A, 76C. Continuous operation of the projector is possible in the " TAPE " mode due to the contact 38B being closed. When threading is complete, light sensitive transistor 22 senses a signal on the film, thereby causing it to conduct and power relay 38 to close contact 38A and activate the recorder 6, at the same time contact 38B is opened. Further if, in the " TAPE " mode, the projector is to operate for a period longer than the discharge of capacitor could sustain, a long signal on the tape energizes the relay 60 for sufficient time for a time delay circuit 81 to activate relay 76. The shorter signals, already described, do not activate circuit 81 because the capacitor 64 does not become sufficiently charged to cause transistor 68 to conduct. Relay 76, when so energized closes contacts 76A, 76C so that the tape recorder 6 remains powered, capacitor 64 is bypassed and thus the relay 76 remains energized. The energization of the relay 76 also opens contacts 76B, so de-energizing relay 38 to open contact 38A and close contact 38B. The closure of contact 38B permits the continuous operation of the projector and the recorder 6 still functions because contacts 76C are closed. Cessation of the signal on the tape opens contacts 60A, de-energizing relay 76 which opens contacts 76C and closes contacts 76B to power relay 38 to close contacts 38A and keep the tape recorder 6 operative.