Patent GB-677124-A (GB)
Title: Photographic contact printing apparatus
IPC: G03B27/08
Filed: 1949-03-15
Abstract: 677,124. Photographic contact printer. PARIS, C. March 15, 1949 [March 15, 1948], No. 7096/49. Class 98 (ii). A continuous and reversible feed photographic contact printer comprises a casing having a rigid front panel which supports interchangeable reel assemblies for a negative picture film, a negative sound film, and a lightsensitive film, and has means for guiding these films so that the path of the light-sensitive film has one point in common with that of one negative and another point in common with that of the other negative. This panel also supports interchangeable optical units for exposing the light-sensitive film at said points in its path, and means are provided for automatically regulating the amount of light striking the light-sensitive film at said points. The printer shown comprises a casing having a front panel across which a negative picture film 3, Fig. 1, is fed from a reel 1 to a reel 2 over a continuously rotating sprocket 60 and a negative sound film 6 is fed between reels 4 and 5 and over another continuously rotating sprocket 60. At said sprockets, the negative films respectively contact a light-sensitive film 9, which is fed between reels 7 and 8. Each sprocket 60 carries the films 3 or 6 and 9, Fig. 3, by its flanges only and is mounted in a casing 631 apertured at 63 to form an exposure slot. This casing includes a lamp 53 from which the light passes through condensers 56 and diffusing screens 55 on to mirrors 54 whereby the light is directed through variable apertures defined by screens 68, 69 on to the slot 63. The negatives 3 and 6 are each provided with marginal notches and pass between rollers 71, Fig. 1, on their journey to the sprockets 60. The rollers 71 are mounted on levers which are pivoted and spring-biased to maintain the rollers in contact with the edges of the films 3 or 6. These levers carry contact plates arranged opposite fixed contacts. Rings connect the contacts with solenoids 94, Fig. 7. When the rollers 71 enter notches in the negative 3, one of the solenoids 94 is energized, the other solenoid 94 being energized when the rollers enter notches in the negative 6. Energization of a solenoid 94 causes a lever 92, spring-urged at 93, to rock and move out of a notch 91a in a disc 90 which carries a cam 95 and is secured to a shaft 88 to which is frictionally connected a disc 89. This disc carries a projection 102 for co-operating with adjustable stops on a fixed ring 104, and has movable and fixed contacts 96, 97. During a revolution of the disc 90, whose stop-lever 92 has been momentarily released by the energized solenoid 94, the cam 95 closes contacts 96, 97, so that a solenoid is energized through slip-rings 98, 99 and fixed brush contacts 100, 101. When this solenoid is energized, several contact-pins are lowered into engagement with a control film CF, Fig. 1, passing around a sprocket 105, the underside of which is engaged by an equal number of fixed contact pins 117a (Fig. 11, not shown). At the same time, the control film CF is moved on by the distance between consecutive perforations. This control film is provided with the usual sprocket-engaging perforations and with five longitudinallyextending rows of perforations (Fig. 5, not shown), so that each transverse row contains any one of the thirty-two combinations of five perforations. Thus of the contact-pins that are moved, only those which register with perforations in the control film engage the sprocket. Consequently only those solenoids 122, Fig. 15, which are connected in the same circuit as those pins are energized. Each of these solenoids 122 carries by its armature a pulley 124 and a nylon thread 125 is passed around these pulleys from a fixed spindle to a spring 127 and a fixed point 128. In its path the thread also passes around pulleys 126 carrying cams 129, each of which engages levers 130 carrying the screens 68, 69. Hence, by selectively energizing the solenoids 122, the thread is pulled to different extents and causes the opening between the screens 68, 69 and consequently the light intensity to vary accordingly. The printer may also include switches for stopping operation of the printer when a film breaks or a lamp becomes defective, these switches being operated by rollers engaging the films 3, 6 and 9 or by cams frictionally mounted on shafts in the printer. If desired, changes in light intensity may be initiated by a pilot film PF, Fig. 1, instead of by the negatives 3, 6. This pilot film is fed at a slower rate than the negative it replaces and has perforations adapted to activate contacts D or notches adapted to actuate rollers similar to the rollers 71.