GB1499997A - Motor control circuit for a camera - Google Patents

Abstract

1499997 Control of D.C. motors KONISHIROKU PHOTO INDUSTRY CO Ltd 28 Dec 1974 [28 Dec 1973] 55293/74 Heading H2J [Also in Division G2] A camera control circuit comprises a D.C. motor M to drive the shutter and film wind mechanism, a switch GS controlled by the motor to open when it exceeds a predetermined speed and thereby connect a resistor R6 in series with the motor, and a relay RL1 having contacts RL1 -1 in parallel with members G5, R6, which contacts are closed to cause the motor to operate at a maximum speed to drive the shutter, when the shutter release switch SW5 is closed, and are normally open when the switch SW5 is open to allow the members GS, R6 to drive the motor at a reduced speed to wind the film. The arrangement is such that, when switches SW3, SW4 are on their single photograph contact positions S1 S2, the shutter is driven at maximum speed and the film wound at reduced speed, and when on their successive photograph contact positions C1, C2, the motor is driven at maximum speed throughout the period of successive photography. During this period the switch SW5 is continuously closed to close contacts RL1-1 and the remainder of the circuit operates in a manner similar to that described in Specification 1,498,188. For a single photograph the following sequence of operations occurs: (1) Closure of switch SW5 energizes relay coil RL1 and relay coil RL2 through switches SW2, SW3, SW10. Resultant closure of contacts RL1-1 and changeover of contact RL2-1 to contact b causes the motor to drive the shutter at maximum speed. (2) Switch SW10 is opened by a diaphragm mechanism to de-energize relay RL2 and changeover contact RL2-1 to contact a to de-energize and brake the motor. (3) When exposure is completed, switch SW10 closes and switch SW2 changes to contact B. (4) Since switch SW3 has been allowed to open, contacts RL1-1 are opened and contacts RL1-2 are closed, the latter action making transistor TR2 conductive to energize relay RL2 through SW2, SW10 and TR2. Hence the contact RL2-1 changes to b and the motor winds the film one frame at a speed controlled by members G5, R6. (5) Switch SW2 changes over to contact A to de-energize relay RL2 and de-energize and brake the motor in preparation for a repeat of operations (1) to (4) above.