Patent GB-656548-A (GB)
Title: Improvements relating to photographic cameras
Inventor: STUDDERT MAURICE EYRE PERSSE
IPC: G03B19/12
Filed: 1947-05-21
Abstract: 656,548. Photographic reflex cameras. WRAY (CAMERAS), Ltd. May 21, 1947, No. 13713. [Class 98 (i)] A photographic roll-film reflex camera has a roller-blind shutter with two blinds each actuated by a spring, and a shutter release member which releases the blind springs in succession so that they then commence to actuate their respective blinds, the release member being driven by a shutter release spring which is independent of the shutter blind springs and is rewound after each exposure, wherein, on initiating an exposure, first the reflex mirror is released and caused to move from the viewing position and thereupon the shutter release spring is freed to drive the shutter release member so that the latter releases the two blind springs in succession to make an exposure. A hand-wound main spring may be connected to rewind the springs of the release member and of the blinds, and may also re-set the reflex mirror. As shown, Fig. 4, the objective 5 has a quick - pitch screw thread mounted in the camera casing, and is rotatable for focusing by a projecting wheel 148 and gears 149, 150. For focusing, the rays are reflected by a mirror 3 to form the image on the ground face 6 of a pentagonal prism 7, which is housed in a well 145 of the camera casing. The image is viewed, after reflection at the prism faces 8, 9 by an eyepiece 10 through an aperture in the shutter blind 12. A hooked lever 31 engages a projection 32 on a carriage which is thereby restrained from moving upwards on a guide pillar 4 under spring action. The mirror 3 is mounted on the carriage for focusing, and may be hinged to fold against the carriage at the top of its travel. The release button 13, Fig. 6, has a rod 27 with a projection 28 which, on depression of the button 13, rocks a lever 29 on a shaft 30. The lever 31 on the other end of shaft 30 is also rocked and releases the mirror carriage. The carriage may also be released by a clockwork delay mechanism, set by rotating a shaft 35. The mechanism is started by withdrawing a knob 49. and drives a sector 36 with a nose which pushes down a foot 52 on rod 27. A spring 62, Fig. 2, is coiled round a fixed shaft 64. One end of the spring is fixed to the shaft, and the other end is fixed to a sleeve 65 loosely mounted on the shaft. Before an exposure, spring 62 is tensioned and tends to drive sleeve 65, which is, however, held by a detent on a lever 59, Fig. 5, engaging a projection 60 on the sleeve. A second sleeve, carrying a bevel gear wheel 72, Fig. 2, is mounted on sleeve 65 with friction, so that the angular relation between the sleeves can be altered by a shutter speed control wheel 100, geared to the wheel 72 and visible through a window 101. The wheel 100 makes an integral number of revolutions for one revolution of the wheel 72, so that when the shutter has been operated, wheel 100 returns to its original seating. When the mirror carriage reaches the top of its travel it rocks a lever 68, Fig. 5, integral with lever 59 about a shaft 58, releasing projection 60. Sleeve 65 then rotates until projection 60 engages lever 68, its speed of rotation being controlled by a governor. When the mirror is retracted lever 68 rocks back and sleeve 65 completes its revolution. The shutter is of the roller-blind type wherein the following blind 12 is wound on a roller 84, Fig. 4, loosely mounted on a shaft 81, and passes to a spring actuated roller 85. The leading blind 83 is carried on cords wound on pulleys, not shown, at each end of roller 84 and secured to shaft 81, and passing to a spring-actuated roller 95. When sleeve 65 starts to rotate, a pin thereon trips a lever engaging a detent on one of the pulleys on shaft 81, and the leading blind 83 moves down under action of roller 95 to uncover the exposure area. Soon after a pin on the second sleeve rocks lever 75, Fig. 5, away from a detent 77 on roller 84, so that the following blind 12 moves down under action of roller 85 to cover the exposure area. A gear wheel 20, Fig. 2, is driven by a main-spring in a housing 14, and meshes with a wheel 113 on a shaft 114 carrying a bevel gear 115. Gear 115 drives through a bevel gear 116, a wheel 112 which is held against movement by a lever 109, Fig. 4, the tip 110 of which engages a projection 111 on wheel 112. Roller 84 has a projection which rocks lever 109 just before the shutter comes to rest, thereby releasing wheel 112 which turns through half a revolution until another pin 117 thereon engages the lever 109. Pin 117 also engages a projection 118 of the mirror carriage, Fig. 2, moving it down against action of spring 55 ready for another exposure. Wheel 112 turns a wheel 120 fast on shaft 64, which is thus turned to tension spring 62 again. At the same time, wheel 120 turns another gear on shaft 81, which turns to draw up the leading blind. A pin-and-slot connection between the pulleys on shaft 81 and roller 84 causes roller 84 also to turn, drawing up the following blind, once the slit has been closed. At the end of winding, a cutaway portion 120a, Fig. 4, of the wheel 120 reaches the wheel 112, and allows shaft 81 to slip back until the pins on the roller 84 and on the pulley re-engage their respective detents. Bulb exposures are obtained by means of a lever 131, Fig. 2, which rotates a cam 132 which depresses a stirrup bar 134. In this position, one end of the stirrup bar is rocked by depression of the release button 13, bringing the other end into the path of the detent which releases the follower blind, and preventing its action to close the shutter until the button 13 is released. For flash-lamp synchronization, cam surfaces on one of the pulleys on shaft 81 operate two sets of electrical contacts at two different delay periods. The contacts are connected to three terminals on the camera case, and a flash bulb or electronic flash equipment is connected to two of the terminals, according to the desired delay. The film movement is also effected by the spring-driven wheel 20, which is geared to film-engaging sprockets 122 through gears 113, 123. The sprocket shaft is also geared to a gear wheel 127 which drives the film take-up spool through a slipping clutch 128. Wheel 127 carries a graduated dial 129 visible through a window 130 in the camera casing. The gearing is such that the dial advances one division more than a complete revolution each time the film is advanced, thus showing the number of exposures made against a mark on the window 130, which is rotatable by hand. The camera includes a photo-electric exposure meter by which the shutter speed is set according to the amount of light entering the objective, as described in Specification 656,595. According to the Provisional Specification, a rheostat in series with the meter may be adjusted to allow for the emulsion speed of the film.