Patent GB-191228948-A (GB)
Title: Improvements in and relating to Photographic Printing Apparatus.
Inventor: CLARK NELSON DE
IPC: G03B27/16
Filed: 1912-12-16
Granted: 1914-02-16
Abstract: 28,948. Clark, N. de. Dec. 16. Printing - apparatus for rapid printing on separate sheets; with automatic time-exposure devices.-In printing-apparatus for printing on separate sheets, a two-part platen 23, 24, Fig. 2, is operated by a treadle 51 connected with jointed toggle links 26, to obtain the printing pressure and to close the main lighting-circuit switch 52. Another switch 36, Fig. 14, is provided whereby one, two, or three of the lamps 32, 33,34 may be used for printing. An electric time mechanism may be switched into circuit by the switch 70, whereby the printing-lamps are automatically switched off after a predetermined printing interval. A counter is used to indicate the number of prints made, and a stamp 66, Fig. 5, prints a serial number on the back of each print through an opening in the section 24 of the pressure platen. The stand may be fitted with side compartments and shelves 18 to hold developing and other apparatus. The togglelinks 26 in one construction are operated by a link 51<a> and a bell-crank 55, one end of which engages underneath a weighted attachment 57 on a slotted bar 29 directly operating the toggles 26. The bell-crank is connected with the pistonrod 30<a> of a dash-pot 31<a> to prevent a too sudden opening of the pressure platen by the treadle. The bar 29 is connected with the pistons of a second dash-pot 31 to prevent a too sudden opening of the pressure platen when opened by hand. A lever 90<a>, Fig. 3, operated by a button 90 is used to tilt the negative for manipulating the print. On operating the treadle the main switch 52 of the lighting circuit is also closed. The counter for registering the number of prints consists of a series of number-disks 60, Figs. 7 and 8, each disk carrying a ratchet 61 on one side and, excepting the unit - disk, a spring- controlled pawl 62 on the other side. The unitdisk is operated by a rod 59 and pawl, actuated from the weighted arm 29. On each complete revolution of each disk the pawl 63 rides over a cam 64 and actuates the adjacent disk on the left by one step. The serial numbering-stamp comprises a band 66, Fig. 5, with the numbers, carried by a bracket 65 on the section 24 of the pressure platen. The section 23 carries an inking pad 68. By the combined action of the link 67 and pivot 69 the pad is inked on each actuation of the platen. The band carrying the serial number required is positioned by hand. In a modified construction, Fig. 15, of the pressure platen operating - mechanism, the togglelevers 111, 113 are operated from the pedal 101 bv levers 102, 104, 115. The end of the link 115 abuts against a spring 118. On operating the treadle, the pressure platen is first closed without flexing the spring 118. On further operation the spring 118 is flexed, whereby increased printing pressure is put upon the platen, and simultaneously also a projection 119 moves a knife contact to close the switch 121 of the printing-lamps circuit. The section 97 of the pressure platen is pressed by an additional leaf spring 127 and bar 128 on the toggle 111. The link 115 is returned by the springs 105, 118 on releasing the treadle, and the knife contact of the switch 121 is opened by a spring. In the switch 36, Figs. 12, 13, and 14, for enabling one, two, or three of the lamps to be used, three sets of contacts 40-45 are interconnected as shown, and the lamp circuit completed through one, two, or three of the terminals 46<a> on the rotating switch arm 39. To test the lamp circuit, an additional finger 48 carried by the arm 39 is pressed into contact with two terminals 49 in series with all three lamps. The lamp circuit includes, in addition to the switch 52 closed by the treadle, a double-pole switch 88. A ruby lamp 50 is always in circuit and a second lamp 74 for indicating when the time-mechanism is in use is normally in circuit excepting when the time - mechanism is working. The timemechanism is put into circuit by another doublepole switch 70. On closing this switch, the electro-magnet 71 is energized and breaks the contact 89 cutting the lamp 74 out of circuit. The setting-arm 79 for controlling the exposure is rotated away from an arm 77 according to the time scale 79<a>. The arm 77 is driven by clock-work, but is initially held against a fixed starting-stop 81 by a spring brake 75, Fig. 10. When the switch 52 is closed by the pressure platen, the electro-magnet 72 is energized and retracts the brake 75, releasing the arm 77. After the printing interval, the arm 77 reaches the arm 79, and contacts 78 thereon complete a circuit through electro-magnets 82, 87. The electro-magnet 82 operates to attract an armature 83 and through links 85, 85<a> and pulley gearing 84 returns the arm 77 to starting position against the stop 81. The electro-magnet 87 acts on an armature on the double-pole switch 88 and opens the printing-lamp circuit. The electro-magnet 71 is thereby de-energized and the switch 89 automatically closes, putting the indicating-lamp 74 into circuit.