Patent GB-836451-A (GB)
Title: Photographic printing apparatus
IPC: G03B27/08
Filed: 1957-04-10
Abstract: 836,451. Photographic contact-printing apparatus. EASTMAN KODAK CO. April 10, 1957 [April 12, 1956], No. 11691/57. Class 98(2) In a printer in which discrete photographic elements are successively printed on to a continuous length of film, and a movable carrier has apertures in which the elements are supported for exposure, the elements are picked directly from a supply stack and seated in the apertures but are inverted after removal from the carrier and before they are inserted in a take-up stack. As shown, a stack of small tranparencies 10 are placed in hopper 19 and transferred individually into apertures 23 in intermittently rotated dics 22. The transparencies are drawn downwards from the retaining lips of hopper 19 by contact with plunger 48 which has an open central bore to which a vacuum is applied during the downward stroke. Each is retained in an aperture 23 by resiliently urged members 29. At zone 17 platen 118 seals channel 25 by means of gasket 26 and a gasket on which the transparency rests marginally and the channel is connected to vacuum line 117 thus ensuring intimate contact between the transparency and the film F. On release of platen 118 by continuously rotating cam 109, the tension in film F acting on sprocket 67 lifts a lever (Fig. 5, not shown), which carries platen 118 and so frees the disc. The continued step-wise motion of disc 22 carries the transparencies from the zone 17 to inverting drum 120 which has an even number of sides each having an aperture 127 corresponding to an aperture 23. This drum turns the transparencies over so that when they are reprinted their emulsion sides will come into contact with the emulsion of the film F. The transfer of the transparencies to drum 120 and from drum 120 to hopper 19<SP>1</SP> is effected by means shown in Fig. 8 in which two plungers 136 and 147 are driven by cams 149 and 158. Plunger 136 carries tubes 137 and 138 and during its upward stroke is connected to a vacuum line 145 through bore 144 which is unblocked by downward movement of plunger 147 so that reduced portion 148 thereof lies in the bore. Before plunger 136 reaches its highest point, plunger 147 begins to rise and unblocks bore 146 which is open to the atmosphere so that the vacuum is broken and the transparencies disengaged from tubes 137 and 138. The transparencies are retained on drum 120 by resiliently urged rollers 133 extending through slots in upstanding ribs 129. The disc 22 may be driven by means of a continuously rotating crank, a connecting rod and an electromagnetically operated brake shoe which locks the end of the connecting rod with the periphery of the disc when the former moves in one direction and allows the connecting rod to return without the disc in the reverse direction. Alternatively intermittent motion is imparted to disc 22 by a Geneva gear (Fig. 1). Sprockets 64, 69 and 71 are intermittently driven by a Geneva gear and the lengths of film fed by sprocket 69 are slightly greater than those fed by sprocket 72 and slightly less than those fed by sprocket 64 so that counterbalanced loop-forming sprockets 66 and 71 always move in a direction to increase their loops. For a repeat print disc 22 is maintained stationary by an electromagnetically operated pawl while the film F is changed and plungers 136 and 147 move as in a printing cycle, but plunger 48 is disconnected electromagnetically. A cam-operated switch lights the printing lamp during the dwell period of disc 22.