Patent GB-672374-A (GB)
Title: Improvements in or relating to photographic timing devices
IPC: G03B15/00
Filed: 1950-02-24
Abstract: 672,374. Photographic cameras for recording race-finishes, J.D.C. ENGINEERING, Ltd., and COOPER, A. Feb. 24, 1950, No. 4879/50, Class 98 (i). [Also in Group XIX] Relates to an embodiment of the photographic timing device described in Specification 631,104, in which means for continuously moving a photographic film past the aperture of a photographic camera are combined with apparatus for marking the film photographically at timed intervals, the said apparatus comprising a light source, an optical system additional to the camera lens system for bring- ing light signals originating from the source to a focus on the film for recording time marks thereon, a disc, partly lighttransmitting and partly opaque, mounted for rotation in the path of the beam from the light source to modify the light signals therefrom, and means to rotate the disc stepby-step in synchronism with desired intervals of time to be recorded. According to the invention the means to rotate the disc for modifying the light signals comprises a rotary member operatively connected to the disc, driving means for the rotary member, said driving means including two actuators capable of co-operating with the rotary member to control its rotation so that it rotates a step at a time when the actuators are operated alternately, and means for operating the actuators alternately at timed intervals corresponding to the desired intervals of time to be recorded on the film. As shown in plan in Fig. 1, a compartment of the camera contains a film spool 17 from which film is fed across a slit-form aperture 34 in a film gate to a driving sprocket 18, and thence through a slot in the casing to a reeling or processing compartment. One edge of the slot 34 is movable, and one edge is fixed and vertically intersects the optical axis of an objective lens in a mount 16 on the casing wall; the axis of this lens provides the finishing line. Below this compartment is a second compartment, Fig. 2, containing a motor 19 which is geared to the shaft of the film-driving sprocket 18. When the motor is electric its speed is controlled by a variable resistance; otherwise a governor 20 and speed-regulating lever 21 are provided. The film is made to move at the same speed as the images of the contestants formed thereon at the slit. A third compartment at one side of the camera contains a cathode-ray tube 2. The brightness or position of a spot on this tube is controlled by a quartzcrystal-controlled electrical impulse generator, and light from the spot passes through a semitransparent mirror 1 and a lens 14 in the camera casing and is reflected on to the film by a prism 15 placed in front of the slit 34 at one end thereof. Marks are thus formed on the film at intervals of <SP>1</SP>/ 100  sec., with longer marks at <SP>1</SP>/ 10  sec. intervals, in the manner described in Specification 631,104. The generator also causes a lamp 4 to flash at intervals of 1 sec. Light from the lamp passes through a lens 5 to illuminate one of a series of transparent numbers peripherally arranged on an opaque disc 3, passes thence through an aperture 54 in a platesupporting tube 2, and is reflected by mirror 1 and prism 15 on to the film. Disc 3 is mounted on a shaft 7 which also carries a disc 11 of non- magnetic material (e.g. plastic) which carries thirty polepieces 53. Solenoids 8, 9 are mounted near the edge of disc 11 and energized by the generator alternately at 1 sec. intervals, thereby rotating the disc one revolution in one minute, so that numerals are printed on the film at intervals of 1 sec. as the lamp 4 flashes between the movements of the disc. A heart-shaped cam 10 is also mounted on shaft 7. A lever 13 is pivoted at 55 on a bracket 56, and is rocked to press a roller 12 against the cam to bring disc 3 back to zero after the operation of the camera. In a modification, Fig. 3, shaft 7 is driven by a continuously-running electric motor 57 through a friction gear 58, 59, 60. The disc 11 is replaced by a disc 62 having thirty projecting pins 63. A lever 65 having a bifurcated end 64 and an armature 69 is pivoted at 66, and is rocked in alternate directions by solenoids 67 alternately energized at 1 sec. intervals. The forks are staggered, and each fork engages each pin 63 in turn to stop disc 62. After operation of the camera, lever 13 is operated as before to bring disc 3 back to zero, and a projection 70 added to lever 13 engages a second bifurcated end 68 of lever 65 to hold that lever in a central position wherein the pins 63 can pass between the forks 64.