Patent GB-231109-A (GB)
Title: Improvements in apparatus for producing photographic prints
IPC: G03B27/16
Filed: 1924-01-01
Abstract: 231,109. Lawley Apparatus Co., Ltd., and Lawley, H. V. Jan. 1, 1924. Printing-apparatus.-In apparatus having means for varying the intensity of the printing light according to the density of the negative, a number of receptacles for printing papers of different classes are provided, together with means actuated by the removal of paper from said receptacles for controlling the intensity of the printing light according to the class of paper selected. In the form shown, the device is applied to a form of printing- apparatus disclosed in Specification 229,443 in which an apertured disc D for supporting the negative and printing paper, rotates above apertured casings A, C containing the printing lamp A<1> and a non-actinic inspection light source respectively, and is secured to a rotatable spindly e<2> extending into the casing A. Receptacles h, h<1>, Figs. 1 and 4, for two kinds of printing paper have means operated by their hinged lids h<2>, h<3> for varying the resistance in the printing light circuit according to which paper is withdrawn. Each lid on being raised engages a segment i<1> on a rotatable disc i<20> which rocks a shaft i<5> by means of a rod i<3> and arm i<4>. A bell-crank lever i<11>, Fig. 6, is rotatably mounted on the shaft i<3> and is attached to the free end of a coiled spring i<10> the other end of which is secured to the shaft. One arm i<1> of the lever i<11> has a pin i<13> engaging one or other of two cam surfaces j, j<1> on a collar j<2> secured to the spindle e<2>. The other arm j<3> carries an insulated terminal screw j<4> for the conductor and a contact point j<6> adapted to make and break contact with a switch plate i in the resistance circuit to vary the resistance. When the lid h <2> is raised for withdrawal of a paper it causes rocking of the shaft i<5> and tensioning of the spring i<10> which tends to force upwards arm i<12> which is however retained until the disc D is rotated to bring the negative and paper from grading to printing position. The arm i<12> then moves upward, and contact i is made and is not broken until the lid h<2> of the box h<1> is raised, rocking back the segment i and restoring the parts to the former position. A lever i<15> is attached to the segment i<1> for manual operation. Each lid may be closed after raising it as the adjustment is not changed until the other lid is raised, the shaft i<5> being held in position by a cam i<6> thereon acted on by a spring i<7>. The coil p, Figs. 8 and 9, for varying the resistance according to the paper used, is contained in a casing B and can be initially adjusted by bus-bars p<3>, p<4> co-operating with contact slides p<5>, p<6> each having a manipulating knob p', p' having pointers working over a graduated scale adjustably mounted on the top of the casing. A resistance coil p<1> in the casing B is used to control the intensity of the printing lamp in a manner similar to that described in connection with the light-intensity controlling device of Specification 220,257, in which on depressing a suitable key a resistance may be cut in or out of the lamp circuit to reduce or increase the intensity of the printing light whilst maintaining a constant exposure period. The printing lamp circuit includes main r, slide p<5> or switch i and slide p<6>, printing lamp A', switch l<4>, conductor r' and main resistance coil p'. The Provisional Specification also describes the use of a light-intensity controlling device, of the general character described in Specification 180,189, in the printing light circuit.