Patent GB-996189-A (GB)
Title: A focal length control unit for attachment to a camera
IPC: G03B19/18
Filed: 1962-03-06
Abstract: 996,189. Focal length control unit for cameras. K. VOCKENHUBER. March 6, 1962 [March 9,1961], No. 8544/62. Heading G2E. A focal length control unit for attachment to a camera having a continuously-variable focal length objective and focal length adjusting means comprises means for mounting the unit detachably on the camera, a driving motor and step-down gearing connecting the driving motor to driving means adapted to be coupled with the focal length adjusting means on the camera. As shown (Fig. 1), the setting knob 3 of a variable focal length objective 2 on the main camera body 1 is coupled to an electric driving motor 5 housed in a detachable handle 4 by way of a partially toothed ring 21 (detachably mounted on the knob 3), transmission gearing 11-17, a friction clutch 9 and gear wheels 7 and 8. Energisation of the motor 5 which is powered by batteries 6 (Fig. 2-not shown) in the detachable handle, is controlled by a rocker 22 operating a polarity reversing switch 23 (Fig. 4- not shown), whereby drive in the two opposite directions is obtained. Speed of setting of the focal length is adjusted by a variable resistor 27 in series with the motor 5 and controlled by a knob 29. Gear wheels 17 and 16 are mounted on a plate 18 rotatable about a spindle 14 against loading of a spring 19. This facilitates meshing of the teeth of gear portions 17 and 20 when the handle 4 is being attached. The means for mounting the handle on the camera are shown at 30-33 (Fig. 3). The camera may be mounted on a tripod by threaded means 24 in the handle and cable release sockets 25, 26 (Fig. 4-not shown) are provided adjacent the switch 23 for remote control of the motor 5. In place of the clutch 9, providing overload protection for the motor 5 when the knob 3 reaches an end of its adjustment range, switches 49, 50 (Fig. 7) may be provided in the circuit of the motor 5 (cf. Fig. 8-not shown). These switches are operable, against loading of a spring 53, by the worm 12 which in this case is axially movable. In a modification (Fig. 6) the motor 5 is pivotably mounted at 36 on a bracket 48. It is spring urged into a medial position but may be pivoted by moving a bracket 42 so as to bring a friction wheel 37 on its shaft into engagement with either one of friction wheels 38, 39, which are coupled to the knob 3 through gearing as before. This movement from said medial position is arranged to close a switch for energizing the motor. The motor mounting bracket 48 is slidably mounted in the wall 43 of the handle for varying the speed of adjustment of the knob 3. In a further modification (Fig. 9), the motor 5 and modified transmission gearing 62-66 and 69-71 are accommodated in a housing 57 which fits flat along the base of the camera (and is screwed thereto) and the motor 5 is connected via a lead 60 to batteries 59 housed in the body of the camera and providing power also for an electric camera driving motor (not shown). A U-shaped handle portion 75 is pivotally mounted on the housing 57 and may be folded flat thereon when not in use. Buttons 73, 74 for control of motor 5, are both provided with cable release sockets. A disengaging device may be provided for holding the gear wheel 71 out of engagement with the toothed segment 20 against spring loading.