Patent GB-190913934-A (GB)
Title: Improvements in and relating to Photographic Copying, Enlarging adn Reducing Apparatus.
IPC: G03B27/36
Filed: 1909-06-14
Granted: 1910-06-09
Abstract: 13,934. Marks, E. C. R., [Print Weave Co.]. June 14. Enlarging, copying, and reducing.-Relates to apparatus for copying and enlarging in which the focus is maintained automatically in adjusting for different scales of enlargement. The means for this purpose comprises a lever 36, Fig. 7, adapted to slide in a fulcrum member I, which has a fixed position relatively to a movable frame carrying one of the elements C. One end B of the lever moves in synchronism with this element C and the other end of the lever imparts the necessary movement to another element A. From Fig. 7 it will be seen that by adjusting the movements of the parts in such a manner that C B is always equal to C B<1> while the distance of I from C A or C B remains constant (corresponding to the focal length of the lens) the focus will be maintained for any scale of enlargement. The apparatus is adapted more especially for a step and repeat machine, in which the enlargement is adjusted to obtain a definite number of repeats to fill the periphery of a printing-roller. The lens and object are carried upon two slides of which that carrying the lens is carried upon a support, while that carrying the object is movable upon the slide carrying the lens. Also a source of light is provided on the slide carrying the object so that the source of light may move with the object when the slide is adjusted. The sensitive plate is mounted on a frame having transverse shafts 11, Fig. 2. The plate is vertically adjustable in the frame to obtain the vertical rows. The frame 10 carrying the lens slide 13 and copyholder slide 40 is mounted on the transverse shafts, and is horizontally adjustable to obtain the horizontal repeats. The lens slide 13 is mounted on guideways in the frame 10, and the copy slide 40 is mounted on guideways on the lens slide 13. The lens slide 13 carries a depending frame 14 and is moved by the screw spindle 32, which is mounted in the bracket 27 on the frame 14 and turns in the nut 33 on the frame 10. The spindle 32 is turned by the worm 29 at the end of the spindle which gears with wheels on two vertical spindles 25, which are in turn actuated by worms 26 in gear with the wheel 22 on the grooved shaft 20. The grooved shaft 20 carrying the operating-handle 21 is mounted in the frame 10 and journals in the bracket 24, which is provided with bearings for the spindles 25 and is also fitted with a yoke 23 for retaining the wheel 22 in gear with the worms 26. The spindles 25 are guided in the lower and upper brackets 18, 27 on the frame 14. The rotating of the adjusting-shaft 20 and the spindles 25 in addition to adjusting the lens slide 13, serves also to adjust the copyholder. The spindles 25 are screw-threaded to the lower end with a thread corresponding to the thread of the spindle 32. A yoke 34 moves on the thread and carries pivots for the lower ends of the levers 36, which pass through swivelling fulcrum slides on the frame 14 and at the other end pass through pivoted slides 38 on the copy slide 40. On rotating the shaft 20, the yoke 34 and pivots of the levers 36 are thus moved vertically through the same distance as the lens slide is moved horizontally by the spindle 32, thus maintaining C B, Fig. 7, always equal to C B<1>. The fulcrum slides are pivoted in the blocks 41 and are slidably adjustable by means of the nuts 44 in slots 42. The slots are placed so as to hold the centre of the blocks 41 always at equal distance from the centre lines in the direction of the motion of the pivot 38 and yoke 34 respectively. The blocks allow for lenses of different focus corresponding to the distance of I from C B or C A, Fig. 7, which is thus kept constant. The lantern 48 is carried upon an arm 47<a> on the copy slide 40, and moves with the object when the slide is adjusted.