Patent GB-1487022-A (GB)
Title: Cinecamera capable of effecting time exposures
IPC: G03B19/18
Filed: 1975-01-22
Abstract: 1487022 Cinematographic cameras NIPPON KOGAKU KK 22 Jan 1975 [22 Jan 1974] 2828/75 Headings G2A and G2E A cinematographic camera is operable in three modes, in which (1) exposures are made in a continuous series; (2) successive long time exposures are made by opening the shutter, leaving the shutter open, and closing the shutter; and (3) successive short exposures are made by moving the shutter through its open position in one cycle. As shown in Figs. 1, 2 an electric motor 19, when energized, drives a gear-wheel 20, which meshes with a gear-wheel 21 of larger diameter fixedly mounted on a shaft 22. Shaft 22 is also fast with a shutter segment 23 which is rotated past an exposure aperture 24. Shaft 22 also operates film transport mechanism between exposures, by means not shown. Both shaft 22 and gear-wheel 21 are conductive and earthed. Two similar insulating areas 25a, 25b are formed opposite each other on the margin of the face of gear-wheel 21, and a contact 18 makes a circuit with gear-wheel 21 except when it rests on an insulating area. In effect, the switch 18 in Fig. 1 opens and closes during the rotation of gear-wheel 21 as shown in Fig. 5B. Similarly, insulating areas 26a, (26b) (see also Figs. 3, 4 not shown), formed as part annuli within the margin, constitute with a sliding contact a switch 9, Fig. 1, which operates as shown in Fig. 5C. A cam 29 on shaft 22 operates a switch 14 as indicated in Fig. 5D. Fig. 5A shows how the shutter segment 23 opens or closes aperture 24. Solenoid coils 10, 16 are wound on a common core 35, which co-operates with a lever 32 which is pivoted at 33 and urged by a spring 34 into a position wherein its end 32a acts as a stop for one of two projections 27, 28 mounted 180 degrees apart on gear-wheel 21. It can be disengaged by energizing coil 10, which attracts an armature 32b and closes a switch 17 to energize motor 19. Coil 16 is not strong enough to move the armature 32b, but can hold it in position after coil 10 is de-energized. In a modification, one of the stops 27, 28 is omitted, and a second lever similar to lever 32 is mounted diametrically opposite the first. Succesive exposures. Switch 12 is set to contact 12a, and a button B is pressed, closing a switch 4 and moving a contact of a switch 3 from contact  3a to contact 3b, so that a capacitor 2, previously charged from a power source 1, row discharges  through the base-emitter path of a npn transistor 8. This transistor is so connected in a circuit with a pnp transistor 6 that they act like a SCR, and both rapidly attain a state of full conduction. The emitter-collector current of transistor 6 flows mainly through coil 10, actuating lever 32. Current also flows through switch 12 and diode 13 to holding coil 16, and to charge capacitor 15, switch 14 being closed at this stage. Actuation of lever 32 closes switch 17, so that motor 19 drives gearwheel 21; when the gear-wheel has rotated through an angle # 1 , switch 9 is closed Fig. 5C to ground the base of transistor 8 and to short-circuit capacitor 2. Current through coil 10 is thus interrupted, but coil 16 continues to operate as long as button B is pressed down to keep switch 14 closed, so that an exposure is made and the film is advanced sequentially for each revolution of gearwheel 21. The series of exposures is halted when button B is released, restoring switches 3, 4 to their original positions. The operation of capacitor 15, discharging through holding coil 16 after switch 4 is opened, and of the switch 18 Fig. 5B, ensures that the gear-wheel 21, whatever its position when button B is released, will continue to rotate until lever 32 engages stop 27 (not 28), so that the apparatus always comes to rest with the shutter closed. Switch 18 may be omitted if the inertia of the moving parts is sufficient to carry gear-wheel 21 into engagement with the stop 27. Exposures of given duration at manuallycontrolled intervals. Switch 12 is set to contact 12b, so that capacitor 15 is charged through transistor 6 as long as it is "on", and switch 4 does not affect the coil 16. On completion of a revolution of shutter segment 23, the apparatus stops with stop 27 engaging lever 32. Even if button B remains depressed, no further action takes place; to make another exposure button B must be released and depressed again. Exposure and interval both manually controlled. Switch 12 is set to contact 12c, so that coil 16 cannot be energized. When button B is depressed, the shutter 23 rotates to the open position, where, since coil 16 is not energized, it is stopped by engagement of stop 28 with lever 32. The shutter remains open, whether button B is released or not. When button B is released and depressed again, the shutter moves to its closed position until button B is released and depressed to open the shutter. The sequence may be thus continued at will. Second embodiment, Fig. 6 (not shown). Capacitor 15 is replaced by a capacitor (40) which, when switch 14 is closed and switch 4 is open, discharges through series resistors (41), (42). The junction of these resistors is connected to the base of a transistor (43) with the holding coil 16 connected in its emitter-collector path. Thus coil 16 is energized while capacitor (40) discharges. By choosing high values for resistors (41), (42), the capacitance of (40) is made less than the capacitance of 15. Third embodiment. As shown in Fig. 7, a single actuating coil 10' replaces the coils 10, 16. One end of coil 10 is connected to the power source 1, and the other is grounded via a resistor 51 and the normally open contacts 69 of a relay 68. With switch 12 on contact 12a and switch 4 closed, relay 68 is energized and contacts 69 are closed. Two currents pass through coil 10'; a large current through a reverse-current-preventing diode 52 and transistor 8, which current is sufficient for movement of lever 32; and a small current through current-limiting resistor 51 and the closed contacts 69. When the transistors 6, 8 cease to conduct, only the small current passes, and this is sufficient to hold lever 32 in position. When button B is released, the apparatus operates in a manner similar to that described with respect to Fig. 1 and at the proper time relay 68 is de-energized, contacts 69 open, no current flows in coil 10' and lever 32 returns for engagement with projection 27. Fourth embodiment, Fig. 8 (not shown). Similar to the second embodiment, but the transistors 6, 8 are replaced by a SCR (62). A switch (61) operated by a cam (66), Fig. 9, 10 (not shown), switches the SCR on and off at the required times in the cycle of operation. Fifth embodiment. As shown in Fig. 11, the transistors 6, 8 are omitted. When a succession of exposures are to be made while button B is held down, switches 120, 220 are moved on to contacts 120a and 220a. When button B is depressed, switch 3 operates to discharge condenser 2 over time #, through coil 10, so that motor 19 starts. Capacitor 15 is charged through switch 120 and operates the holding coil 16. The circuit operates otherwise as described above. When one exposure is to be made for each operation of button B, the switches are turned to contacts 120b, 220b, so that capacitor 15 is charged by capacitor 2 and switch 120, instead of being charged via switches 4, 220. When the exposure is to be made between the times of actuating and releasing button B, the switches 120, 220 are moved to contacts 120c, 220c, and capacitor 15 is not charged. Sixth embodiment, Fig. 12 (not shown). Similar to the circuit of Fig. 11, but a transistor is used, as described above, for switching the holding coil 16. Seventh embodiment, Fig. 13. The actuating coil 10 and the holding coil 16 are combined as a single coil 10'. When a series of exposures is required as long as button B is depressed, switches 320, 420 are closed. When button B is depressed, switch 3 causes capacitor 2 to discharge through coil 10', which actuates the lever 32. Holding current through switch 4 flows until button B is released, whereupon the apparatus stops with the shutter closed. When an exposure is required each time the button B is depressed, switch 320 is open and switch 420 closed. When an exposure is to be begun and finished at successive operations of button B, switches 320, 420 are both open. Eighth embodiment, Fig. 14 (not shown). A generator (80) is driven by the motor 19, so that when the motor is running D.C. is produced to activate the holding coil 16 to keep the apparatus running when the button B is released until the shutter is closed.