Patent GB-1454044-A (GB)
Title: Camera
IPC: G03B27/32
Filed: 1974-01-25
Abstract: 1454044 Copying cameras MINNESOTA MINING & Mfg CO 25 Jan 1974 [26 Jan 1973]  03653/74 Headings G2A and G2J A document-copying camera has a pair of transport rollers 39, 43 with a flat plate 41 between them forming the focal plane, against which the document is positioned, and a pair of pressure rollers 40, 44 parallel to the transport rollers but spaced closer together, so that the document is guided and kept in close contact with the plate 41. The original document is passed into the camera between guide-plates 34, 35, and enters the nip between a first transport roller and pressure roller 39, 40, is passed to a second transport roller and pressure roller 43, 44, and is then guided out of the camera by a plate 36. Rollers 39 and 43 have raised collar portions, as seen more clearly in Fig. 2, so that the plate 41 lying between the collar portions can present a document-contacting surface co-planar with the outer surface of the collar portions. The axes of rollers 39, 40 are off-set, and the axes of rollers 43, 44 are also off-set but in the opposite direction. Thus a document passing between rollers 39, 40 has its lead edge guided down on to plate 41 and is maintained flat against its surface until its trailing edge passes between rollers 43, 44. The illumination is provided by two fluorescent lamps 31 housed in shields having slot-openings 48, 49. The film is contained in a removable cassette 11, and winds from one spool 20, over a spring- biased roller 12 against which it is held by an idler roller 26 and a drive capstan 25, on to another spool 20. The film is driven from the supply spool by the capstan 25, and taken up on the other spool which-is driven by a spindle 21 engaging with its hub. Both the capstan and the spindle are driven from a motor 50, which also drives a counter 95. The transport rollers 39, 43 are also driven from motor 50, so that the film and the document move in synchronism. The illuminated image of the document is projected along a folded path which crosses itself twice, being reflected from a first mirror 67 to a second mirror 68, thence to a third mirror 72, and so to the lens system 65 which focuses it on to the film. The lens has four elements and an aperture stop as shown. The parameters and physical characteristics of the elements are given. Mirror 68 is adjustable so as to compensate for any variations in the optical path and so control precisely the image reduction. The shutter is formed by a plate 85 positioned over a slot aperture. The plate is at one end of a cantilever arm (seen more clearly in Fig. 6 not shown), which is drawn to one side by a solenoid 87 to uncover the aperture. When there is no document in the camera the drive motor and all other moving parts are stationary. When a document is inserted, its presence is sensed and the motor and lamps are energized. The camera can be operated in two different modes. In one, called the trailing edge mode, the leading edge is sensed to switch on the equipment, which remains energized until a predetermined time after the trailing edge has been sensed. Thus the film will be advanced for a time determined by the length of the document. This is useful for copying small documents or documents of different lengths. In the other mode, called the leading edge or framing mode, the film is advanced for a set time after initiation by the leading edge. Figs. (not shown) 8 and 9 give a block diagram and the circuitry for controlling the operation of the camera, the required mode being selected by a switch. Means are provided for detecting and indicating the end of the film, and for exposing a portion of the film near one edge to provide a locating mark.