Patent GB-718902-A (GB)
Title: Improvements in or relating to photographic contact printing apparatus
Inventor: PITT FREDERICK HENRY GEORGE
IPC: G03B27/06
Filed: 1951-07-04
Abstract: 718,902. Photographic contact printers. KODAK, Ltd. July 4, 1952 [July 4, 1951] No. 15879/51. Class 98(2) A photographic contact printer comprises means for automatically coupling driving means for a strip of light sensitive paper to a continuously rotatable shaft at the completion of each exposure and manually operable means for pre-setting a control member which, after a predetermined number of exposures, couples the rotatable shaft to a guillotine for severing the paper and/or a numbering device for stamping an identifying number on the back of the paper. The printer shown is of the kind described in Specification 718,970, [Group XL(b)], and comprises a lamp house 2 mounted on a mechanism housing 1, Fig. 1, and enclosing a lamp 6 and reflectors 7, 8, Fig. 2, directing light through apertures 9 in the floor of the lamp house and through apertures 4, 5 in a mask 3 fixed to housing 1, these apertures registering with apertures in the top of housing 1. Below aperture 5 in the mask 3 is disposed a photo-electric cell 21 in circuit with a micro-ammeter 22 and a variable resistance 25 which is mechanically coupled with a shaft 17 carrying the movable contact 20 of an auto-transformer 18 in circuit with lamp 6, and a trigger 16 connected by a cable 15 with a normally spring closed shutter 14 for the aperture 9 which is disposed above mask aperture 5. In use, the image area of a negative N which is next to be printed is positioned over mask aperture 5, trigger 16 is operated to open shutter 14 and thereby allow light to pass through the negative onto the photo-electric cell 21, and knob 19 is adjusted to vary the lamp brightness until the micro-ammeter indicates that the brightness of the lamp is satisfactory for that image area. The value of shunt resistance 25 is increased automatically as the lamp voltage increases adapted to engage with' a stop lever 62 wherebyto compensate for the different light sensitivities of photo-electric cells and photographic paper. When the lamp brightness has been adjusted, the negative N is moved to register the image area with the mask aperture 4, lamps 27 in a case 28 having a light filter 29 aiding this operation. A strip of light sensitive paper P, Figs. 2 and 6, is movable in a direction perpendicular to the direction of movement of the negative across a glass plate 30 below aperture 4 and is pressed into contact with the negative by a pivoted platen 31 when an exposure is to be made. As shown in Fig. 6, this paper P is fed from spool 37 and guided by rollers 46, 47 across the glass plate 30 and by a driving roller 49 and a spring loaded pressure roller 50 between parallel plates 54 and out through the bottom of the mechanism housing 1. Exposure is effected during one revolution of a timing shaft 61, Figs. 3 and 4, fast with the inner casing 60 of a roller bearing clutch, the outer casing 59 of which is secured to a gear 57 meshing with a pinion on a shaft 55 which is driven by a continuously running electric motor. A pin 64 on casing 60 is adapted to engage with a stop lever 62 whereby rotation of the timing shaft is prevented. This stop lever is pivoted at 63 to a wall 38 and at 65 to a link 66 pivoted at 67 to an arm 68 which is rotatably carried by a sleeve on wall 38 and the downward movement of which is limited by a projection 71. The sleeve also carries a lever 72 spring urged at 74 into contact with a plunger 73, Figs. 1 and 4, depression of which removes the stop lever 62 from pin 64 so that timing shaft 61 can rotate through. one revolution. The shaft 61 carries a cam 86, Figs. 3 and 4, engaged by a roller 84 on a pivoted spring loaded lever 82 linked at 80 to the pressure platen 31, the cam being arranged on the shaft so that during the last part of the rotation thereof the platen 31 is raised sufficiently to permit sliding movement of the film N and paper P. Springs (not shown) lower the platen during the initial rotation of cam 86, and a separate treadle and linkage is preferably provided to raise the platen sufficiently to allow replacement of the film and paper when needed. Cams 87, 88, Fig. 3, on shaft 61 are adapted to operate micro-switches 13, 13<SP>1</SP>, Fig. 2. When platen 31 has been lowered during initial rotation of shaft 61, cam 88 closes switch 13<SP>1</SP> to open shutter 11 to effect an exposure; cam 87 subsequently opens switch 13 to terminate the exposure. During the last part of the rotation of shaft 61, cam 88 opens switch 13<SP>1</SP> and cam 87 closes switch 13 in readiness for further exposure. The exposure time may be varied" by relative angular adjustment of the cams 87, 88. For this purpose, cam 87 is carried by a sleeve 89, Fig. 3, freely mounted on shaft 61 and carrying an index drum 90 which is releasably locked to the shaft by a spring loaded detent 91 carried by the shaft and selectively engageable with teeth 93 on drum 90. Also coupled to the continuously rotating shaft 55  is a gear 58, Figs. 3 and 4, secured to the outer case 94 of a second roller bearing clutch, the inner case 95 of which is secured to a shaft 96 driving the paper feed roller 49. A pivoted stop lever 97 has one end spring urged at 99 into the path of a pair of diametrically opposite projections 100 on the clutch part 95 to prevent rotation of paper drive shaft 96. This lever 97 is tripped to release shaft 96 at the end of the platen raising operation by a pin 101 on the cam 86 engaging the other end of the lever. Thus, the paper P is allowed to move during the time taken for half a revolution :of clutch part 95 and after completion of an exposure to position a fresh area of the paper on the glass plate 30. For applying an identifying number to the work ticket attached to negative film N a stamping device 106 is provided, Figs. 4 and 6. This device comprises a yoke 107 in which a type carrier 108 is carried by a plunger 109 which may be depressed onto the work ticket carried by a rest 111 to stamp the number, whereupon the carrier is returned to its inoperative position by a spring and the identifying number is increased by one digit. In order to ensure that the work ticket is stamped on depression of knob 110, a lever 168, Fig. 4, is pivoted at 169 to the bracket 112 and engages a nose 173 on the type carrier 108. Upon fully depressing knob 110 so that the type strikes a work ticket on the rest 111, the nose 173 is moved downwards and lever 168 is turned by spring 174 so that the bearing surface 172 thereon prevents the return of the type carrier in the yoke 107 and thereby prevents the type being changed. During this movement the other end of lever 168 has moved into the path of a pair of pins 175 on a disc 176 secured to the paper drive shaft 96. Thus. when the latter is released to advance an unexposed area of photographic paper P across the mask aperture 4, one of the pins 175 turns lever 168 to release the nose 173 and permit the return movement of the type carrier 108 so that the identifying number is increased by one digit. If the type carrier is not fully depressed in the yoke it is held in its partially depressed condition by a shoulder 171 on lever 168 which prevents return of the type carrier until lever 168 is released by'one of the pins 175 on the disc 176. A guard 177 is pivoted between brackets 179 and has a finger 180, Fig. 4, spring connected with lever 168 at 181. In the inoperative position of lever 168, the spring 181 pulls the guard into the position shown in Fig. 1 where it prevents a film strip being 'laid on a film guide 182 extending on both sides of mask 3. The guard 177 is lowered to an inoperative position when the type carrier 108 is engaged by the bearing surface 172 on lever 168. Thus the raised guard 177 serves to remind the operator that an identification number must be stamped on the work ticket of the new film strip before it is positioned on the guide 182. Depression of the plunger 109 causes yoke 107 and a bracket 112 carrying it to descend against the action of springs (not shown). This descent of the bracket causes pre-setting of mechanism for initiating operation of a guillotine comprising a fixed blade 103 and a movable blade 104 in the path of the paper P as it leaves the housing 1 (see Fig. 6). The guillotine pre-setting mechanism comprises a pinion 114 on the timing shaft 61 and in mesh with a gear 115 rotatable on a shaft 116 on wall 38. Gear 115 has seven studs 118, Fig, 7, each carried by a rotatable stem 119 and the studs are movable between operative and inoperative positions defined by a spring loaded detent. The studs are selectively turned to the operative position by engagement of a control finger 125 with a pin 126 projecting from each stud, this control finger being pivoted at 127 to the wall 38 and carrying a lever 128 formed with a slot 129, Fig. 6, engaged by a pin 130 projecting from a lever 131 on bracket 112. Thus, upon depression of bracket 112 by knob 110, the control finger 125 is pivoted as that its tail lies in the path of the pin 126 of the adjacent stud 118<SP>1</SP>. Rotation of gear 115 will then carry stud 118<SP>1</SP> past the finger 125 which will cam it into its operative position. When the shaft 96 is rotated, finger 125 is returned to its initial position so that another stud 118 will not be rendered operative until further depression of the stamping device. A disc 133 is secured to shaft 116 so that it is not rotatable with gear 115 and a cam 135 thereon serves to rotate the studs 118 to their inoperative positions after they have initiated the operation of the guillotine, Each pin 126 comes to rest beneath a conical member 136, Fig. 7, carried by a rocker arm 137 which also carries a pair of pins 139, Fig. 6, engaging a groove in one element of a dog clutch 140 and, when a pin 126 is in its operative position, it engages member 136 and rocks the arm 137 so that the elements of the dog clutch are engaged and a shaft 141, Fig. 3, is coupled to a sl