Patent GB-685329-A (GB)
Title: Improvements in or relating to a photographic printing frame
IPC: G03B27/58
Filed: 1950-08-10
Abstract: 685,329. Photographic printing frames. LEITZ GES., E. Aug. 10, 1950 [Aug. 11, 1949], No. 19916/50. Classes 98 (i) and 98 (ii). The frame comprises an electromagnet the armature of which is mechanically linked to a mask hinged to the base for lifting the mask when the electromagnet is actuated, and a device operable by the said electromagnet for ejecting the printing paper from the frame on lifting the mask. As shown, the frame comprises a base member 1 having a paper-supporting surface 27 and a hinged platen member 3 having adjustable masking bars 4. Movement of the platen is controlled by engagement of a pinion 5 thereon with a rack on a member 6 slidably mounted on bolts 8. The weight of the platen tending to close the frame is partly counterbalanced by springs 9 surrounding the bolts, and to raise the platen solenoids 10 are energized, as by closing a foot switch 12, attracting the rack member 6. The closing of the frame may be controlled either by a dashpot 57, having two sets of vents parallel to the cylinder axis at different distances along it so that the platen initially moves slowly and then shuts rapidly, an inlet valve at the closed end being opened as the piston is withdrawn on raising the platen; or the platen may close initially to a position determined by a pivoted blocking member having its opposite limb engaged by a lever pivoted on the base and linked to a second pivoted lever which may be manually operated against a spring to move the blocking member to allow the platen to close. A support 30 has a recess 30a engaged by a guide block 31 so that by rotating a pivoted lever 34 the support is slid along the base. Journalled on the support at 29, 32 respectively are a rockable frame 19 urged clockwise about its pivot 18 by a spring 20 and a block 28 having a tail 28a. Pivoted on the frame 19 and urged clockwise by a spring 24 is a block 22 having a nose 22a and carrying a cranked strip 23 which extends through a slot in the paper support 27 and, with the frame in the closed rest position, clamps the printing paper 26 against it. With the solenoids energized and the platen raised, an extension 13 on the rack member engages an adjustable screw 14 on a lever 15 pivoted on a pin 15b parallel to the frame hinge and so depresses the end 17 of the lever, rocking the frame 19 anticlockwise about its pivot 18 so that the strip 23 rises to release the paper and when the nose 22a engages the tail 28a the strip strikes the edge of the sheet 26 to eject it from the frame. A fresh sheet of paper is then located on the support 27 against the slotted strips 23, 43. By movement of the support 30 the width of the clear margins of the print may be varied equally, the strip 43 being carried by a block 41 guided by pegs 42 to allow lateral movement only and having a slot 41a engaged by a peg 40 on the support 30. Each of the slots in the paper support 27 has a castellated inner edge to receive and permit adjustment of the strips 23, 43 which project through them. A print counter 61 operated by a finger 59 on the platen is provided.