Patent GB-490286-A (GB)
IPC: G03B27/20
Filed: 1937-02-06
Abstract: 490,286. Photographic printing - apparatus. GENERAL PRINTING INK CORPORATION. Feb. 6, 1937, No. 3613. Convention date, Feb. 6, 1936. [Class 98 (ii)] In a step - and - repeat contact - printing machine the printing-plate holder is carried by a supporting frame, and sealing means are provided between the plate holder and the frame and between the frame and the sensitive surface ; alternatively, the plate holder is carried by an adapter carried by the supporting frame, sealing means being provided between the plate holder and the adapter, between the adapter and the frame, and between the frame and the sensitive surface. In each case the seal between the printing plate and its holder is a double seal. The machine shown comprises a base 1, Fig. 1, vertical pillars 2 mounted on the base and connected by a cross beam 4 which extends sideways beyond the pillars, a rail 60 mounted on the base and supporting a carriage 63, Fig. 17, consisting of a framework 65, 66 with means for holding a backboard 101, and mechanism for operating the movable parts. Smooth surfaced panels 6 are carried by the extensions of the cross beam 4. The plate holder supporting frame F is mounted for vertical adjustment on a pair of screw-threaded shafts 9 and is connected at its upper and lower edges to curtains 13, 14 carried on rollers on the framework. The shafts 9 are connected by gearing to a common pinion on a shaft carrying a micrometer disc 33 and driven by gearing from a motor M. The drive may be adjustable to eliminate backlash. The sealing arrangements are shown in Fig. 3. The frame F is reduced at its inner edge 172 to receive sealing strips 174, 175 and carries also an upper angle iron 180 supporting clamping screws 181 and a lower bar 182 provided with lugs having clamping screws 184. The adapter A consists of a rectangular frame held in place by the screws 181, 184 and provided at its inner edge with a sealing strip 202. The plate holder P is recessed at its outer edge to co-operate with the sealing strip 202 on the adapter, and is located in position by dowel pins on the adapter engaging in dowel holes in the plate holder, being secured in place by screws 198. The printing plate is held in the holder P by means of edge clamps 222 and the gap between the plate and the holder is sealed by the frame 225 carrying a channel-shaped sealing member 227, held in place by screws 216 carried on pivoted arms 215 on pillars on the plate holder P. The sensitive surface 240, Fig. 17, is carried by the backboard 101 hinged at its lower edge to arms 122 carried by levers permitting of to-and-fro movement on the standards 65, movement being imparted to the arms 122 by lever mechanism driven from the motor 158, springs being employed to absorb shock. For loading, the backboard is lowered into horizontal position, the sensitive surface being secured thereon by e.g. adhesive tape, and is then raised to vertical position, rods on the backboard being moved into sockets on the arms 122. The plate holder is moved vertically and the backboard moved horizontally into position for the first exposure. The backboard is then moved into contact with the printing frame, the sealing ring 174 on the supporting frame F engaging the surface of the backboard, and the air is exhausted from the space. After exposure, the backboard and plate holder are moved to the next printing position. A warning lamp may be provided showing when the printing is in progress.