Patent GB-440787-A (GB)
Title: Improvements in or relating to power driven photographic cameras
IPC: G03B17/53
Filed: 1934-05-22
Abstract: 440,787. Photographic cameras. GROVES, W. W., 30, Southampton Buildings, Chancery Lane, London.-(Folmer Graflex Corporation ; 154, Clarissa Street, Rochester, New York, U.S.A.) May 22, 1934, No. 18574/35. Divided out of 433,657. [Class 98 (i)] A motor-driven roll-film camera has a cycle mechanism driven by an electric motor and controlling electric circuits adapted to operate mechanism to permit the film to be fed by the motor, and mechanism for actuating the shutter, the camera having also a film-measuring roll provided with means for controlling an electric circuit for the purpose of maintaining the film-feeding mechanism in operation until a predetermined length of film has been fed. As shown, the camera comprises a body 1, Fig. 1, housing a removable film magazine 21 secured by a screw 22, the body being detachably bolted to a chamber 2 which is provided at its base with a panel 18 supporting a lens 16 mounted in a shutter-casing 17, at its inclined wall with an inverting mirror 11, and at its front with a hood provided with chambers 9 containing lamps 10 for illuminating the object. The lens panel 18 carries a solenoid whose core is pivoted to the shutter trigger. The magazine 21 comprises: (1) chambers 25, 26, Fig. 2, in which the film supply-spool 27 and the take-up spool 29 respectively are mounted, the chamber 26 enclosing also a spiked film measuring-roll 37, a film guide roll 40, and a gate member 42 which is pivoted at 43 to facilitate threading of the film, and carries film guide rolls 39, 41 and a plate 44 which engages the back of the film in the focal plane 24 when the gate member is closed and secured by a spring latch ; and (2) a chamber housing the motor 56 which drives through worm gearing a shaft 59 carrying a pinion 62 driving a gear train 64 ... 67, Fig. 4, mounted on the front wall 63 of the magazine 21. On this wall are also mounted insulating blocks 68 ... 71 carrying spring contacts actuated respectively by a pin 75 on gear 66, a cam 81 on gear 67 and a cam 89 on the shaft 38 of the measuring wheel 39, Fig. 2. The wiring of the various parts is completed through contact members such as 128, 129, 131 which engage one another when the body 1, chamber 2, and magazine 21 are assembled. The lamps 10 remain continuously in circuit when the plug socket on the body 1 is connected to the mains. The film is driven from the gear train 64 ... 67 through a clutch associated with the spindle of the winding-key 31 engaging the take-up spool 29, the clutch yoke member 115 being operated by a crank 117 on a shaft 118 having an arm 120 rocked by solenoids 121 and 122, and being biassed into the unclutched position by a spring 126. The key spindle is also hand-operable, to facilitate threading of the film, by a knob 99 acting through an overrunning clutch. The operation of the camera is controlled by a switch button (not shown), on the inclined wall of the chamber 2. When the mains plug is connected, the lamps 10 light up, an adjustable current is sent through an auxiliary braking winding of the motor 56 and a current is passed through the solenoid 121 to maintain the film driving clutch in the unclutched position. A short pressure on the switch button closes a temporary circuit through the main winding of the motor and starts the gear train 64 ... 67. Thereafter stud 75 on gear 66 actuates contacts on block 68 to open the braking circuit and establish a working circuit of the motor. Assuming that the first picture area has been brought into the focal plane 24 as described in Specification 433,657, by hand winding of the knob 99, or by a succession of actuations of the switch button, the first exposure is made when the cam 81 on the gear 67 actuates contacts on the block 70, completing a circuit through the shutter-operating solenoid on the lens panel 18. The cam 81 is detachable and may be replaced by a cam of different length. After thus effecting the exposure, the cam 81 next engages contacts on the block 69, throwing out the unclutching solenoid 121 and throwing in the clutching solenoid 122 to commence the drive of the take-up spool 29. The length of the cam 81 is not relied upon to determine the amount of film fed because of the increasing diameter of the film roll on the take-up spool 29. For this reason the cam 89 on the measuring roll 37 is employed ; it commences to turn under the action of the moving film and actuates contacts on the block 71 to maintain the film-driving circuit after the cam 81 has left the contacts on the block 69 until the cam 89 has completed one revolution, when the contacts on the block 71 are restored to initial position and feed ceases. The gear train then returns to its initial position ready for a second exposure, to be initiated by pressing the switch button again. A variable resistance is included in the circuit of the motor braking winding. Compensation is provided for voltage fluctuations by feeding the lamps 10 and the motor from the same mains and by winding the motor so that its speed varies with the applied voltage. A diagram showing the wiring of the electric circuits is given.