Patent GB-908340-A (GB)
Title: Photographic printer machine
IPC: G03B27/46
Filed: 1960-02-04
Abstract: 908,340. Photographic printing-machines. PAKO CORPORATION. Feb. 4, 1960 [March 10, 1959], No. 3973/60. Class 98 (1). A photographic printing machine comprises a casing, to which is detachably secured a first magazine containing a print paper supply spool, and a second magazine containing a paper take-up spool, the casing and both magazines having light-locks for excluding light from the apertures where the paper passes from one magazine into the casing, and from the casing into the other magazine; the casing contains means for intermittently progressing the print paper past an exposure aperture. Fig. 2 shows the upper deck of the apparatus, with the central casing 16, and the magazines C and D attached one at each end of the casing, holding the supply and take-up rolls 63 respectively. These magazines, which are detachable and interchangeable, are secured to the central casing by pins 102, 103, 104 which engage in holes in spring tongues as at 99 and 281, so holding the magazines in secure but readily removable attachment to the casing. The printing paper X passes from a supply spool 63 in magazine C through the casing 16 and is taken up on a similar spool 63 in magazine D, each magazine having a cover 78 which can swing open about a hinge 80. Secured to the same shaft 58 as the paper spool 63 is a spool lock 64 having a number of notches 74 round the periphery. A spring- loaded locking device 65 is normally retained in the position shown in Fig. 2, but as the magazine is lifted slightly for detachment from the casing the lock 65 is released and thus pulled down by the spring 73 so that its lower limb engages in one of the notches 74. The paper spool is thus prevented from rotating and so unwinding as the magazine is removed. On the inner wall of magazine C is provided a light-lock 112, having rollers 135, 137 mounted therein. The sensitive paper passes from spool 63, over guide rollers 107, 108 and guide plate 125, through the lightlock 112 into the central casing. Here, after passing over a paper advance roller 44, it passes round the feed roller 35 which is mounted on the main driving shaft 26. On shaft 26 is a sleeve 27 having opposed slots 28 therein, and a pair of flat circular flanges 31 are removably keyed into appropriate slots according to the width of paper to be accommodated between them. The paper then passes over an aperture 251 in a support plate 250, against which it is held by a covering plate 253. In this position the exposure is made. The bellows 14a connects the casing 16 with a table (Fig. 1, not shown) which carries the negative, the light source, and electrical exposure timing means. An alarm device 255 has an arm 259 which is responsive to splice-holes in the paper, and produces an audible warning signal to prevent printing in the spliced area. After exposure, the paper passes under rollers 260, 261 and over a take-up roller 263, through a light-lock 112<SP>11</SP> similar to lock 112<SP>1</SP> on the inside of casing 16, and then into magazine D, where after passing through a further light-lock 112<SP>111</SP>, the paper is finally taken up on a spool 63. The advance roller 44 is mounted on an arm 46 pivoted at 47, and connected by an arrangement of springs and levers 49, 49<SP>1</SP>, 50, 51 to a brake shoe 56. This acts against a pulley 57 mounted on the shaft 58 carrying the paper spool 63, so that the shoe 56 can act to brake or release the motion of the spool. In the positions of roller 44 and arm 46 shown in full lines in Fig. 2, the brake is applied. After the exposure has been made, feed roller 35 is rotated by the drive assembly to advance the paper. The roller 44 and arm 46 are thus pulled downwards by the paper into the position shown in broken lines. This releases the brake, and allows the paper spool 63 in magazine C to turn. After roller 35 has rotated a predetermined amount, it stops, and roller 44 is drawn up again by its loading spring into its initial position. This draws a length of paper off spool 63 before it is again braked. Thus when roller 35 is once more rotated, a length of paper is ready to be advanced without having to overcome the inertia of the spool and mass of paper thereon. At the take-up end, the take-up spool 63 in magazine D is rotated by a slip-clutch 290 driven from the motor 297. As the paper advances, the take-up or cushioning roller 263 moves from the position shown in full lines to that shown in dotted lines. When the advance of the paper is stopped by roller 35, the take-up spool 63 continues to rotate and wind paper thereon, and as this occurs roller 263 is drawn downwardly again by the pull of the paper, so providing a cushioning effect against the possibility of paper movement at the support 250. The drive shaft 26 is rotated intermittently by the drive assembly generally designated B. Secured to the shaft 26 is pressure disc 157, in which an outer race 155 can rotate freely on an inner race 153. The pressure disc has sprockets 160 which are driven by a chain 300 from the motor 297. A plate portion 161 of the disc 157 is separated by a felt washer 162 from a ratchet 163 formed as part of the hub 152 which is keyed to shaft 26. When the ratchet is restrained from rotation by the head portion 195 of a latch arm 188, the felt washer acts as a friction slip clutch. The latch arm 188 pivots about a shaft 190, and is actuated by the armature 196 of a solenoid 196<SP>1</SP>. When it is actuated anticlockwise (Fig. 22) to latch out of ratchet 163 and allow rotation, a screw parts 201 at the same time releases a spring-loaded shaft 185 and engages a pressure slide 179 into contact (via a friction ring) with a switch breaker arm 174. This controls the operation of a series of contacts on a contact disc assembly 202 (Fig. 25), which is formed as a series of alternate conducting and insulating plates. The shaft 26 now rotates, and the paper is advanced. At the same time the breaker arm 174 rotates from the position shown in full lines (Fig. 25) to that shown in dotted lines, when it engages contact lifter 221 and separates contacts 220 and 211, thus de-energizing solenoid 196<SP>1</SP>. Spring 198 then draws the head portion 195 of arm 188 into engagement with ratchet 163, so stopping rotation of shaft 26. The assembly 202 can be adjusted to vary the length of paper advanced during each operating period.