GB834732A - Photographic contact-printing apparatus - Google Patents

Abstract

834,732. Photographic contact printing apparatus. CHEMISCHE FABRIEK L. VAN DER GRINTEN N.V. Jan. 31, 1958 [Feb. 6, 1957], No. 3339/58. Class 98(2) In a contact printing apparatus, a friction element acts on superposed original and copy sheets, while they are being conveyed from an exposure position to a movable separating element, to advance the sheet which is about to be engaged with the separating element relatively to the other sheet. As shown in Fig. 1, the original A and copy material B are carried in superposition by an endless belt 3 about a transparent rotating cylinder 1 having a light source 2. The sheets are guided by lifting brush 5 on to belt 6 where the copy material B is advanced relatively to the original A by frictional engagement with rotating disc roller 9 and its leading edge is guided around disc roller 10 by separator 11 so that the latter scrapes up the leading edge of original A from the guided surface of B. In another form (Fig. 4) the sheets are retained on the underside of belt 3 by air pressure or static electrical charges: If the original A is in advance of B it may be held by suction in the region of roller 16 until Breaches the roller 16 and the suction thus no longer acts directly on A so that it falls on to counter rotating friction roller 9 and is retarded. Meanwhile B is advanced between roller 16 and separator 11. A is only advanced again when its adhesion with belt 3 is greater than the force of retardation exerted by roller 9. Alternatively, the sheets may be blown against roller 9. In another form (Fig. 5) the superposed sheets are held under tension against a braked friction disc roller 9 by the greater speed of belt 22 relative to that of belt 3. The sheets are retained on belts 3 and 22 by a difference in air pressure. Developer is applied to copy material B by rollers 17, 18 and .19 from troughs 20, 21. Rollers 9 may consist of thin spaced discs of rubber or "Mipolan" (Registered Trade Mark) or may be coated with rubber. Alternatively, the relative movement of the sheets may be effected by reciprocating rubber fingers. The separator 11 may be in the form of small plates separately pivoted on a shaft (Fig. 6, not shown) or in the form of a bar. More than one print may be made at a time by feeding several exposure sets through the apparatus side by side.