GB1480981A - Photographic camera - Google Patents

Abstract

1480981 Photographic cameras ROBOT FOTO UND ELECTRONIC GmbH & CO KG 7 Aug 1975 [26 Sept 1974 4 March 1975] 33042/75 Heading G2A A photographic camera with a claw-feed film changing mechanism driven by an electric motor, has a rotary shutter driven by another electric motor and an electric control device for releasing the rotary shutter, the electrical control device being actuated by sensors responsive to the movement of the film drive motor. Film feed is driven by a motor 10, Fig. 1. Film 12 is fed from a spool 14 to a sprocket 16 to a film gate 20, back to sprocket 16 and to a take-up spool 46, driven through a slipping clutch. The film is advanced through the gate between exposures by reciprocating claws 28, 30 of a clawfeed mechanism also driven by motor 10. Motor 10 also drives a disc 52 with an aperture 54; light passing through this aperture energizes in turn sensors F1-F6. Shutter. Consists of a disc 54 with a cut-out portion 58, driven by a shutter motor 56. Photodiodes VL, VR are energized intermittently by light passing through arcuate slots 60, 62 of different radius and formed in disc 54, extending over about 170 degrees. Photo-diodes V2, V3, V4, in conjunction with the edges of cut-out 58, detect movement of disc 54. A second shutter motor 66 drives a generally semicircular vane 64, which has arcuate slots 68, 70 corresponding with slots 60, 62. Sensors VL', VR', V3', V4' correspond with sensors VL, VR, V3, V4. Optical system. The objective lens 72 forms an image on the film 12 at the gate 20. A secondary image is formed near the edge of the gate by a lens 76 and a reflecting prism 74 mounted on a carriage 78 slidable in a shoot 80 and urged into operative position at the top of the shoot. A reflex viewfinder comprising a mirror 86, field lens 88 and eyepiece 90 can be introduced into shoot 80, displacing carriage 78. Control of film drive motor. The apparatus as a whole is controlled by a logic circuit Fig. 2 (not shown) which comprises flip-flop circuits and NAND gates. The film drive motor 10 generates pulse signals in the sensors F1-F6 at different angles of rotation of the motor, which signals are fed to the logic circuit. The motor also drives a tachogenerator (G), Fig. 2 (not shown), which produces a voltage in proportion to the motor speed. This voltage is compared with a fixed voltage and the result signal, dependent on three different exposure rates, sets up different conditions in the logic circuit. Shutter motor 56 is energized to drive disc 54; after 360 degrees rotation of disc 54 the power to the motor is cut off and replaced by a reverse voltage to correct over-shoot. The speed of the motor is increased as the interval between exposures decreases. Shutter motor control. The point in the cycle of operation at which the shutter disc 54 begins to rotate depends on the speed of the film drive motor 10. When the exposure time is 1/500 seconds or less, the sensors V3, V4, VL, VR, are taken out of circuit, and replaced by sensors V3', V4', VL', VR'. The motors 56, 66 are then energized by increased voltage.