Patent GB-855734-A (GB)
Title: Improvements in or relating to apparatus for viewing or reading microfilms
IPC: G03B21/11
Filed: 1957-10-15
Abstract: 855,734. Optical viewing apparatus. CHEROUVRIER, R. E. Oct. 15, 1957 [Oct. 17, 1956; Feb. 25, 1957], No. 32237/57. Classes 97(1) and 98(1) Apparatus for viewing &c., if desired photographically enlarging, microfilm comprises a housing carrying an optical projection head to form an image of the microfilm on a reading surface and a closed film magazine removably secured to the head and including a pair of chambers connected by a gate member for guiding the microfilm between the chambers and a movable glass pane forming a film presser mounted in the gate, an automatic device being provided to move the glass pane to filmclamping position when the film is stationary and a reversible drive for controlling the direction and speed of travel of the film. As shown, (Fig. 2) the image of a micro film in a projecting device 9 having an objective 12, is directed on to a translucent viewing screen 5 by means of a plane mirror 8. The device 9 houses two film forwarding motors 11, and is mounted for rotation about the axis of the objective 12; the film is housed in a magazine detachably contained in the device 9 and having feed and take up compartments into which the shafts of the driving motors 11 project and which are separated by a transparent gate which is located under the objective 12. The film F passes between glass windows 48, Fig. 6, and during projection is pressed against the upper window by means of a glass presser element 51 in a frame 52, which is brought into play when the drive motors stop by means of a linkage actuated by a brake engaging a drum on the spindle of one of the drive motors; an alternative presser actuating device is dependent upon plate being loosely coupled to a toothed wheel fast with one of the drive motor spindles such that the presser element 51-normally spring urged in operative position-is released during film drive. To alter the relative positions of the motors 11 to accommodate magazines of different size; one of them is mounted on the periphery of a plate head rotatable by means of a lever. A control panel 102 (Fig. 12), having power input terminals 105 bears a potentiometer 104 foi controlling the projection lamp 107 intensity via a transformer 106, and another-103-for controlling the motors and connected by leads 108, 109 to the terminals of the motors which are of single phase induction type. A terminal 112 of a switch 117 is connected by a lead 113 to the terminals 2, 3 of the motors through,condensors 114, 115 so that the motors are reversibly fed, the direction and speed of film movement being determined by the position of the movable contact of the potentiometer 103. Provision may be made for photographically recording the enlarged micro-image by pivoting the mirror 8 to allow the image to fall upon a surface 132, Fig. 15, carrying the photographic material. The surface is movable to vary the magnification automatic focussing being effected by a lever 135 pivoted at 136 and engaging a sliding cam 139 operating a pivoted lever 140 to move the lens 126. Photographic processing apparatus may also be incorporated.