| 摘要 |
1,212,370. Printing-apparatus. RANK XEROX Ltd. 29 Dec., 1967 [4 Jan., 1967], No. 59085/67. Heading B6C. An image 2 on a relief printing plate 1 is printed on to a sheet or a web 31 by inking the plate with dry ink particles from an inking roller 11 and transferring the inked image on to the web 31 &c. utilizing pressure and a source of potential 41 which establishes a potential difference between the plate 1 and a transfer roller 33. The printing and non-printing areas of the plate 1 are each formed of the same material. The powdered ink is supplied to the roller 11 by gravity from a hopper 17 and comprises fine pigmented electroscopic particles together with coarser carrier material which is triboelectrically charged with a polarity opposite to that of the pigmented material on frictional engagement therewith. Electrodes such as 14 which may be in the form of a curved sheet, a screen, or a series of wires or points maintain a layer of charged particles on the roller 11. A potential source 21 effects the ink transfer to the plate 1 which is spaced up to 3 mm. from the roller 11 and a brush 61 assists the removal of excess ink after printing. The printed image is fixed by a heating unit 45, vapour fusion, spraying &c. with an adhesive film, or by lamination. The roller 11 includes a metallic surface 13 supporting a semi-conductive layer 12. The printing surface may include a conductive layer supporting a thin semiconductive or dielectric coating, may print on to conductive material, and may alternatively be mounted on a flat bed. |
