Patent GB-473683-A (GB)
Title: Improvements in photographic cameras
IPC: G03B19/04
Filed: 1936-03-18
Abstract: 473,683. Photographic cameras. CAMPBELL, R. E. March 18, 1936, No. 13055/35. [Class 98 (i)] In cameras comprising a rotating cylindrical shutter enclosing film supply and take-up spools and an exposure gate &c. the shutter and the take-up spool are operated in sequence by mutilated pinions rotating in unison, one exposure being made during each revolution of the pinions ; the camera may be a reflex camera, and an additional, approximately semicircular, mutilated pinion may raise the mirror and hold it during exposures. As shown, a shutter comprising concentric cylinders C\ C<2>, relatively adjustable to vary the size of three exposure apertures c<1>, rotates about a fixed cylinder B having an aperture b and containing a film gate b<1> and supply and take-up reels D, D<2> respectively. The reel D rotates on a fixed spindle n, but the reel D<2> is mounted on a spindle d<9> carried by an arm d, Fig. 5, rocking about the shutter axis to effect film feeding. The driving mechanism comprises a spring motor E carrying a gear e meshing with a pinion f formed in one with mutilated pinions F, F<1>, F<2>. The pinion F rocks the arm d to draw film through the gate, and has three teeth f<2> on an otherwise cylindrical periphery to engage pinion teeth formed on the arm and rock it through about 90‹. During the rocking movement, the spindle d<9> is held relatively to the arm by a pawl k<1> and ratchet d<5>, but a gear d<1> connected to the spindle by a spring d4 rolls on a rack d<2> and tensions the spring. When the teeth f<2> disengage the teeth on the arm d, the arm returns to its original position, and the spring d<4> rotates the reel during this movement to take up the excess film. The pinion F has five teeth f<3> and an otherwise cylindrical periphery, and rotates intermittently a pinion H secured to the shutter. The pinion H has three sets of teeth h separated by locking teeth h<1> which engage the surface of the pinion F<1> and hold the shutter stationary between exposure movements. A reflex mirror a<1> is provided in the camera shown, and is raised and lowered by the third mutilated pinion F<2> which is approximately semicircular and has three teeth f<5> near the leading edge of its cylindrical surface. These teeth rotate a pinion K, having a locking tooth k<1>, which, through a gear on its shaft meshing with a gear K<1> on the mirror spindle, raises the mirror a<1>; the mirror is held raised throughout the time the cylindrical periphery of the pinion F<2> engages the locking tooth k<1>, and then falls to reflecting position. A pawl k<2> pivoted to the gear K<1> rotates a wheel K<3> one tooth each time the mirror is raised, so that numerals on the wheel K<3> may indicate, through a window in the camera casing, the number of exposures made, and a spring e<2>, variably compressed by a screw e<3>, engages helical teeth on the drum of the motor E to regulate the motor speed. The mechanism is released by a pivoted catch L, Fig. 7, which is turned from one extreme position to the other to permit a single exposure; or is turned to its middle position, shown in full lines, to permit a series of exposures ; in its extreme positions it engages one or other of two pins f<6>, f<7> on the pinion F<1>. The spool D<2> has a slot d<6> through which the leading end of the film is passed and is secured by a screw projecting through the spool into the spindle d<9>. The pressure plate b<2> of the gate carries a spring-controlled plunger b<3> engaging a cam b<4> on the shutter shaft A so that it may enter recesses b<5> therein and open the gate during the film-feeding periods.