Patent GB-1013690-A (GB)
Title: Stereoscopic camera
IPC: G03B35/10
Filed: 1962-06-08
Abstract: 1,013,690. Panoramic stereoscopic cameras. GLOBE INDUSTRIES Inc. June 8, 1962 [June 29, 1961], No. 22372/62. Heading G2A. In a stereoscopic camera, each of the pair of images projected on to the film is subtended over an angle exceeding 90 degrees to give a panoramic effect, the two lenses being mounted with their axes parallel and having means for rotating them simultaneously. The main features of the camera are a pair of twin revolving lenses mounted within cylindrical housing drums having slit-openings for transmission of light. The openings can be covered with light-trap shoes except when exposures are to be made. Additional protection from light is provided by covers which pivot over the lens ports when not in use. Filters are provided within the lens drums, as are also cat's eye iris diaphragms. The lens drums are rotated at high speeds by a clock-spring drive, the speed being controlled by a pneumatic device. The camera comprises three housing portions, a front housing 2, a main housing 3, and a rear housing or film magazine 4. Fig. 4 shows the lens port covers 32, 34 in closed position. They are automatically unlatched and allowed to spring open (as in Fig. 38) by the depression of buttons 74 (Fig. 1) as the cocking lever 90 is actuated and passes over them. The lens drum shells comprise two identical hemispheres 202, 204 (Fig. 9), having slit-apertures, as at 214. Between them is enclosed the lens column 200 and the filter selector mechanism 230. The lens comprises (Fig. 12) elements 236, 238 in a front cell, and an element 240 in a rear cell. The lens column is arranged to pivot on an axis through the second nodal point of the lens system, so as to give a high resolution. The filter housing 230 fits into a cavity 231 in the lens column 200. In the form described, two filters are accommodated in this housing, and can be moved into or out of position by suitable mechanism (Figs. 15-18, not shown) which can be operated from a dial 450 (Fig. 19). Fig. 12 shows one filter lowered into position in front of the front lens element 236, the other raised. A pair of light-trap shoes 168, 170 (Fig. 1) for each lens drum, consisting of pockets containing mohair, can pivot so as to cover the lens ports. The iris diaphragm comprises two S-shaped members 574, 576 (Fig. 22), overlapping so that the lower limbs between them define a cat's eye aperture. It is shown in Fig. 12 as mounted between the front and back cells of the lens, and pivots on a pin 626. Each member carries a roller, 618, 620, and the aperture is varied by the tapered end 662 of a cam pin 660 pressing between the rollers to separate them each iris diaphragm is controlled by a knob 670 attached to a cam 678. The cam carries a spiral cam track 680 against which the top of the pin 660 bears. The two cams are geared together, so that the two diaphragms are actuated in synchronism. The drive for rotating each lens drum assembly derives from a clock-spring motor 740. Attached to each lens column is a drive arm 742 having a pin 748 extending below it and another pin 746 extending above it (Fig. 12). Fixed to the spring motor is a spacer 784, and as the spring unwinds, the spacer engages against pin 746, and so carries the drive arm 742 round with it, thus rotating the lens column. The two lens columns are connected by a drive belt 798 (Fig. 30) so as to rotate in synchronism. To arrest the lens drum at the end of its motion, one of the pins 748 comes into contact with one or other plunger 1862, 1864 of a pneumatic arrester device 1830. To set the mechanism, the cocking lever 90 and its attached cocking gear 1078 (Fig. 31) is rotated clockwise through 180 degrees. The associated right and left gears 812 are consequently turned anticlockwise, but only the right clock-spring is wound up by this movement, the left clock-spring being wound by a reverse movement of the cocking lever. The release mechanism is actuated by a release arm 990 operated by a push button 930. A mechanism to prevent double exposure is described (Fig. 25, not shown), and also a flash bulb circuit, actuated whichever direction the lens mounts may be operating in. The travel of the lens drums during a picture-taking period is monitored by a pneumatic regulator 1300 (Figs. 30 and 36). This comprises a piston 1314 mounted on a plunger 1312; the plunger is carried by a bracket 1308 riveted to the drive belt 798. As the piston moves in one direction or the other, the air pressure built up on the compressed side is allowed to leak out through a metered escape valve, so controlling uniform movement of the piston and hence the scanning movement of the lens drums. Fig. 36 shows the double valve arrangement in more detail. As the piston 1312 moves one way or the other, the air compressed flows into one or other of the diagonal channels 1386, 1388. Both these lead to a central opening 1390, which accommodates a needle valve 1410. The valve is adjusted by the engagement of a pinion 1418 on its upper part with a gear 1472, operated by means of a knob 1460; this has an exposure scale 1474 to indicate the various speed settings. To improve the operation of the valve in regulating the plunger movement to provide a uniform smooth travel, a pair of relief valves 1336, 1338 are provided, one for each diagonal channel 1386, 1388. The film bed 1900 is a double arcuate assembly to mate with the similarly shaped pressure assembly shown in Fig. 44, the latter assembly being spring-urged by pressure pads 2060 and 2064 to engage the film. Focusing is effected by moving the film bed 1900 towards or away from the lens drums, by means of a series of screwed shafts.