Patent GB-784591-A (GB)
Abstract: 784,591. Photographic recording of highsneed phenomena; zoetropes. REMING- TON ARMS CO., Inc. June 1, 1955 [July 28. 1954], No. 15756/55. Classes 97(1) and 98(1) A photographic camera for recording high speed events includes a photographic element carrying carriage with either a lined screen or a sensitized plate mounted thereon and arranged for movement in the focal plane of the camera, the other of the lined screen or sensitized plate which is not mounted on the carriage being stationary, a counter weight carriage also arranged for movement in the focalplane of the camera, and a source of power for moving the first mentioned carriage arranged to act thereon and to react upon the counter-weight carriage, the carriages being thereby accelerated in opposite directions. As shown in Figs. 1, 2 and 3, a rectangular fraine 1 formed of steel tubing constitutes the base of the camera and has three adjustable screw jacks 2 for supporing on a floor. A bracket 3 fixed to the frame carries castors 4, and also supports a vertical steel column 8 on which a lens bracket 9 and a mirror 10 are slidably mounted. A horizontal wooden frame 12 is mounted on the bracket 3 and serves as a support for a light tight housing 49 surrounding the working mechanism of the camera. Scanning system. The scanning system is mounted on an independent sub-frame 14 (Figs. 2 and 3) mounted on the bracket 3. Steel angles 17 are welded to the longitudinal members of the sub-frame 14 and machined to provide an inverted Vee track 18 and a flat track 19. The carriage 20 for suporting the photographic sheet material has single wheels 22 on one side engaging the flat track 19, and spaced wheels 23 on the other side which straddle the vertex of the inverted Vee track 18. A photographic . plate 25 is clamped to the top of the carriage to move just below a fixed line screen 28. The counter-weight carriage comprises a frame 35, Fig. 5, which surrounds the carriage 20 and is supported by its own wheels on the guides 18, 19. A cross member 36 on the counterweight carriage supports a solenoid coil 37 which receives an armature bar 38 mounted on the plate carriage 20. In this position, a spring 39 surrounding a plunger 41 and secured at one end to the cross member 36 and at the other member to a fitting. 40 fast on the shank of plunger 41, is held in tension. As long as the solenoid 37 is energized, the armature bar 38 is held in its Fig. 5 position, and this serves to hold the spring in tension. When the solenoid is de-energized, the spring contracts and the plunger 41 ejects the armature bar 38 from the solenoid, propelling the plate carriage beneath the scanning grid. At the same time, the reaction to the propulsion of the plate carriage acts on the counterweight carriage which is propelled in the opposite direction. At the end of their relative movements, the plate carriage 20 and counterweight carriage. 35 are brought to rest by engagement with the plunger 42 of a pneumatic buffer supported on a cross bar 43 on the counterweight carriage. Camera housing and lens mount. The lens bracket 9, Fig. 2, is joined by bellows 48 to a casing 49 mounted on the horizontal frame 12. The lens 50 may be supplied with an electrically operated shutter which is opened at the moment when the scanning movement begins and closes just after the scanning movement is completed. The camera lens, as shown, points vertically upwards, but the direction of view may be varied by means of the mirror 10 which is an optically flat, front surface mirror. To facilitate focusing, a viewing cell 51 may be temporarily positioned over the line screen 28 and supports a mirror 52 at 45 degress to the lens axis. An image is formed on a ground glass screen 53 at the side of the cell. A plate magazine 55, Fig. 1, is provided in the form of a lighttight box which may be inserted through a port 56 in the top of the camera housing 49. Light-tight sleeves 57 are provided in the front wall of the camera housing and permit manual opening of the plate magazine and transfer of plates between the magazine and plate carriage. Carriage positioning mechanism. As shown in Fig. 9, a manipulator rod 58 is guided for movement through the camera wall, and has a keyway 60 which receives a key 61 in a lever 62 rotatable in the end of the camera housings. Lever 62 is releasably held in a vertical position or in an- 6ther position displaced 90 degrees therefrom. This rotational movement allows a finger 63 at the end of the rod 58 to extend vertically upwards or horizontally. The finger 63 may be turned horizontal, thrust forward, and turned into the vertical position so that on retraction it engages a part of the carriage 20. By means of the rod 60 the carriage 20 can be drawn back and the spring 39 compressed. A latch 65 then springs up to engage the cross member 36 on the counterweight carriage. When solenoid 37 has been energized, the catch may be released by moving forward a sleeve 67 surrounding the rod 58. Operation. The exposure is initiated by electronic means, the first effect of which is to de-energize the solenoid 37, thus releasing- the spring 39, and at the same time operating.the camera-packing shutter to open it. The actual exposure is effected by means of a square pulse light flash which is timed to begin after the period during which the carriages are accelerated by the spring. The event to be photographed may be initiated electrically. For example, a gun may be fired by an impulse occurring just before the light flash is triggered, so that the light flash begins only when the bullet has reached the target. The light flash terminates before the carriages are slowed down by the buffer. In one example, the line screen comprises transparent lines one-thousandth of an inch thick separated by a distance of thirty thousandths of an inch. The duration of the light flash must be less than the time required for the grid to travel thirty thousandths of an inch. To view the image, the plate is removed from the camera, developed, and returned to its original 'position on carriage 20. The carriage is connected to a mechanism whereby it may be virtually advanced by worm wheel reduction gears, while being illuminated by gas discharge tubes 69 (Fig. 2). By this means the record of the event recorded can be studied in detail and in timed sequence. If desired, the plate moving mechanism may be coupled to the advance movement of a standard 16 mm. cinematograph camera, so that an image projected on to a screen is photographed on consecutive frames of the 16 mm. film. Specifications 117,734 [Class 9(i)], 716,365, 716,368, 716,420 and U.S.A. Specification 2,679,618 are referred to.