Patent GB-815318-A (GB)
Title: Improvements relating to stereoscopic cameras
IPC: G03B35/10
Filed: 1956-02-10
Abstract: 815,318. Stereascopic roll-film cameras. BELL, G.M. May 10, 1957 [Feb. 10, 1956], No. 4205/56. Classes 98(1) and 98(2) A photographic stereoscopic roll-film camera has means for recording images of both horizontal and vertical format on a continuous film in such a way that the images lie along the film with their longer dimensions in the same direction. As shown in Fig. 2, singly perforated 16 mm. film is wound on spools 15, 20, the spool axes being parallel to the optical axis of the camera. The film leaving the supply spool 15 passes through a twist 16, to the right-hand film gate 17, and thence passes through a double twist 18 to the left-hand film gate 19. From gate 19 it passes through another twist 21 to the take-up spool 20. The twist 18 enables the gates to be rotated into a vertical position, as shown in Fig. 3, without moving the film with respect to the gates. The twist 18 will accommodate six frames, so that after seven exposures the film must be advanced without further exposure until the frames exposed in the right-hand gate have passed the left-hand gate. The film advance mechanism operates only when the gates are in their horizontal position. Film gates. The gates are similar, and the right-hand gate only is described with respect to Fig. 4, and the right-hand side of Fig. 5, which is a section on the line III-III of Fig. 4. The gate consists of a rectangular opening 25 in a circular plate mounted in an opening 24 in a main assembly plate 23. Guides 26, 27 are provided for the film 28, and a pressure plate 29 hinged at its upper edge, is pressed against the film by a spring-urged plunger 30 housed in the spool pivot. This pressure is relieved when the camera back is opened. The film guides are curved at one end 34 to give the required twist, and at the inner end unites with a flexible film guide which imparts the double twist between the gates. The gates are held in the horizontal position shown, against detents 36, by notches 38 engaged by catches 37 carried on an arm 39 mounted on the assembly plate. The gate units each carry a toothed sector 41 meshing with a spur wheel 42 which in turn meshes with a rack 44 slidable on a column 45. When the catches 37 of the gates are released by actuation of a button 10 (Fig. 1) the righthand gate only is rotated by a spring (not shown) into vertical position, where it is held against a stop. During rotation, rack 44 is driven through wheel 42. The rack has two sets of teeth, and the opposite set of teeth drive the second gate through a similar spur wheel. The toothed sector on the second gate is resiliently mounted to allow some lost motion when the stop is reached. As the rack rises it raises a plunger 7, by depression of which the gates can be returned to the horizontal position, in which they are re-engaged by the catches 37. Viewfinder. The viewfinder is of the inverted Galilean telescope kind, having a rectangular mask. The barrel 109 (Fig. 5) of the viewfinder is rotatable through 90 degrees by a member 108, having a pin- and-slot connection 111, 112 with the camera body, and movable up. and down by the rack unit. Film advancing mechanism. The film is advanced only when the gates are in their horizontal position. As shown in Fig. 4, and in Fig. 5, of which the right- and lefthand sides are sections on the lines III-III and IV-IV respectively in Fig. 4, a member 53 sliding on a rod 58 carries at each end a member 59 carrying teeth 54 which engage the film perforations, and a toe 55 for raising the pressure plate from the film by engaging a projection 33 on the pressure plate. The teeth 54 move a short distance on pins 60, 61 so that the pressure plate is raised before the film begins to move. At the end of a stroke, the pressure plate is released. During the return stroke which is effected by a return spring (not shown) the member 59 rides up over the projection 33, the teeth 54 re-engaging the film perforations at the end of the return stroke. The forward stroke is effected by depression of the plunger 7, which bears on the rounded end 71 of a link 67. the opposite end of which has a rotatable bush 70 with a slot whereby it is connected with a little vertical play, to a projection 69 on the member 53. A toothed sector 68, pivoted at 73 to the camera body, is connected by a pivot 72 to the link 67, so that, on depression of the plunger 7, a toothed wheel 76 co-axial with the take-up spool 20 is rotated by the teeth of sector 68. By means of a rachet connection and a friction clutch, the backward and forward movement of the wheel 76 causes a rotation of the take-up spool 20 sufficient to wind up the film. The wheel 76 engages a gear train 84, 85, 86 for the purpose of winding the shutter (see below). When the gates are rotated to the vertical position, the film-feeding mechanism is lifted clear of the gates. This is effected by rotating the rod 58 in its supports 92, 93. Normally, the rod is held against rotation by a projection 98 thereon which is engaged by a bolt 96 is shown in Fig. 6, which is a section on the line V-V in Fig. 4. When the button 10 (Fig. 1) is depressed, a sliding member 100 moves downwards, and by action of an oblique pin-and-slot connection 101, 102, moves bolt 96 (mounted on the rack 44) to release projection 98. Rod 58 then rotates under spring action until the members 59 are lifted clear of the film gates. At the same time projections 94, 95 at the ends of rod 58 engage the catches 37, so that the film gates are released and move under spring action to their vertical positions and the rack unit 44 moves upwards, as described above. When plunger 7 is depressed to move rack 44 downwards and to rotate the gates back to their horizontal positions, rod 58 is returned to its normal position by bolt 96 bearing on projection 98. The film advance member is held away from the gates until the gates are horizontal by a spring catch 105, which is released by the tip of the rack 44. Shutter. The shutter consists of two similar roller-blind units, Fig. 6, each having a leading blind 115 wound on a drum 116, supported between end plates 135 by a spindle 117, and a follower blind 112 wound on a drum 113, both drums 113 being freely mounted on a common spindle 114. The rigid edge 119 of each follower blind 112 is connected to cords 118 which pass round idler pulleys 120 and are fixed to pulleys 121 fixed to spindle 114 and drums 113. Cords from the edge 122 of each leading blind 115 are fixed to pulleys 123 on a common spindle 124. After an exposure the leading blinds are wound on their drums while the follower blinds are unwound. To re-set the shutter, bevel gears 87, 88 connected to the gears 84, 85, 86 (Fig. 5) are driven by the toothed wheel 76 during the film winding operation. The bevel 88 has a long boss 130 with a finger 131, which engages a projection 132 on a timing cylinder 133 to cause rotation of the shaft 124 to raise the leading blinds 115. Hooks 125 on blinds 115 catch the edges 119 of the follower blinds 112, which, by action of the cords 118, transmit the motion to shaft 114 to wind up the follower blinds 112 as they move in contact with the leading blinds 115. During the winding action, springs 126 within drums 116 and a spring 127 within one of the drums 113 are stressed. The blinds are held in their fully-wound positions by catches 142, 141 engaging projections 128, 129 on pulleys 121, 123 (see Figs. 8, 9, which are sections on the lines VII-VII and VIIIVIII respectively in Fig. 7). When the shutter release button 9 (Fig. 1) is depressed, the leading blinds are released by catch 141 which is disengaged by a pin 143 connected to the button 9 and engaging a slot 144 in the catch. As the blinds run down, shaft 124 rotates with the timing cylinder 133, until an edge 145 on the cylinder engages a finger 146 on a shaft 147 (Figs. 7, 9). The finger moves against a pin 140 on the catch 142, so that the follower blinds are released. To vary the exposure, the edge 145 is step-formed and finger 146 is moved relatively thereto by sliding action of shaft 147, by means of a projection 152 engaging a cam 151 on the shaft of the shutter speed setting knob 8 (Fig. 1). A "bulb" setting is provided wherein the finger 146 is clear of the timing cylinder 133. The follower blinds are then released as follows: on depression of release knob 9 the end of pin 143 remote from catch 141 rides over a hook 150 on catch 142 (Fig. 9) which is thus disengaged on release of knob 9. Film winding sequence. Since there is space for six exposures on the film between the gates, it is required to advance the film one step after each exposure for the first six exposures and to advance it eight steps after the seventh exposure, and so on. Further, release of the shutter or rotation of the gates should be prevented unless unexposed film is in position in the gates. A catch 66 (Fig. 5) retains the film advance member 53 only when the film has been advanced and the shutter wound; when the catch is inactive, neither the shutter release 9 nor the gate rotation release 10 can be depressed. A lever 153 (Fig. 6) pivoted at 154 makes contact with a leg 155 of the catch 66. Light springs urge catch 66 into inactive position and lever 153 away from leg 155. When the shutter has been wound, a cam 163 on the bevel 87, Fig. 7, acting through a lever, moves a member 158 longitudinally so that its hooked end engages the end 157 of lever 153 and rocks it so that catch 66 retains the member 53, the end 157 of lever 153 being retained in position by a projection 164 on one of the pulleys 113, so that the film cannot be advanced until an exposure has been made. In the course of its movement, the lever 158, by means of a pin 166 thereon, advances a 14-tooth wheel 165 by one tooth. After seven exposures, a cam 168 fast with wheel 165 rocks a lever 169 about a pin 91 to prevent projection 164 from retai