Patent GB-706768-A (GB)
Title: Improvements in or relating to photographic reproduction cameras
Inventor: MESSENGER GEORGE EDWARD
IPC: G05D3/12
Filed: 1950-04-27
Abstract: 706,768. Photomechanical cameras with lens and filter turrets. HUNTER-PENROSE, Ltd. April 16, 1951 [April 27, 1950], No. 10441/50. Classes 97(1) and 98(1) [Also in Group XXXVII] Apparatus for selectively introducing alternative elements into the optical system of a photomechanical camera comprises a hollow mounting supported for angular movement about a horizontal axis, and carrying at equal intervals said alternative elements; an electric motor for rotating the mounting a limit switch for each alternative element and operative normally to close the motor circuit; an abutment movable with the mounting to operate a limit switch to open the motor circuit when a fresh alternative element is moved into register with the optical system; an electrically releasable locking device to locate the mounting in such a position; a relay electrically connected with the locking device, the limit switches, and the motor to control the release of the locking device and the operation of the motor until the circuit through the limit switches is restored by movement of the abutment away from the limit, and a manually operable control switch having means operative on cessation of manual manipulation to determine the interval during which the relay is operative. Preferably the first mounting carries lenses and a second independent hollow mounting carrying filters is separately rotatable about said horizontal axis while means for closing to a selected value the normally open diaphragm of each lens are provided at the position in which the selected lens register with the optical system. As shown, three lenses 6 each having a diaphragm with an adjusting ring 62 are carried in a rotatable drum 3 and five filters 81 are carried on an inner concentric drum 80. The drums 3, 80 are each positioned by similar means to bring a chosen lens and filter into line with the axis of the exposing light beam which is reflected by the mirror 10 to the light-sensitive plate. The chosen lens and filter are moved into position by repeated operation of a push-button switch as required. The drum 3 is rotated from an electric motor 7 by means of spring discs 8 engaging a flange 9 on the drum which is located at each of its three alternative positions by a spring- urged locking pin engaging a recess in the drum. To change the lens, a push-button switch having a considerable contact period (see Group XXXVII) is operated, thereby energizing a relay which simultaneously energizes the motor 7 and a solenoid disengaging the locking pin from the drum. The drum then rotates and so allows to return to its normal position that one of three series-connected two-pole limit switches which is reversed by a projection on the drum 3 when the corresponding lens is positioned in register with the optical system, thus providing a hold-on circuit until the next lens is in position when the drum projection operates the corresponding switch to stop the motor, the locking pin engaging an appropriate recess in the drum and a pilot lamp being lit to indicate the lens in position. The diaphragm ring 62 is adjusted by a spring disc drive 71 from a motor 63 and its setting is indicated by a voltmeter in circuit with a variable resistor 74 having its tap adjusted by a spring disc follower 72 driven by the ring 62. The motor 63, resistor 74, and the spring disc units 71, 72 are carried on a plate 64 pivoted to the main frame 4. As soon as the motor is energized a solenoid 69 in series therewith attracts the plate 64 against a return spring so as to move the spring discs clear of ring 62, the solenoid being de-energized with the motor when the next lens is in position so that the spring discs re-engage the diaphragm ring. An arcuate rail 65 is provided to return the diaphragm to its open position by frictional engagement with the ring 62 on changing the lens. If a particular size and shape of aperture is required a band having different apertures in it may be passed through slots formed in the lens barrels, the band having feed perforations and being driven by a sprocket rotated by an electric motor controlled by switch means to select a desired aperture. Visual indication of the aperture selected may be provided. For reversed photographs the mounting for the mirror 95 is rotated through 90 degrees about a vertical axis and the copyboard is moved towards one end of the housing, an image of it being directed to the mirror 95 by a. further vertical mirror at 45 degrees to the axes of both the copyboard and the mirror 95. For effecting a preexposure of the light-sensitive plate to overcome the inertia of its emulsion, a lamphouse 96 movable by conveyer chains 97 driven by an electric motor 99 is provided. Pilot lamps indicating the position of the lamphouse and limit switches 114 and 102, 116 are provided in the motor circuit so that the lamphouse can be readily located in the position shown or at either of the extreme positions. A shutter comprising two part cylindrical members 85, 86 are mounted on ball bearings for movement between the lens and filter drums. The shutter member arms 89, 90 are freely pivoted together on a fixed pin 91 and are connected by links 89b, 90b to a pin 93c on a block movable against return springs 94a with the armature 93 of a solenoid 94 controlled by a hand switch to an extent limited by buffers 130 to open the shutter.