GB1442529A - Multi-colour magnetographic printing apparatus and method - Google Patents

Abstract

1442529 Magnetic printing; selective printing RAYTHEON CO 7 June 1974 [22 June 1973] 25465/74 Headings B6C and B6F Multicolour printing is achieved by magnetizing a magnetizable member 101, Fig. 1 with different states of magnetization corresponding to the different colours, and applying differently coloured tones each of which has correspondingly different magnetic characteristics. In the embodiment, the magnetism is applied by A.C. energized electromagnets, and the state of magnestism is affected by change in A.C. frequency. The recording head applies the magnetic pattern in the chosen state, tone is supplied at 119, untrasonic transducer and roughened surface 106 are effective to enhance the image by shaking off the loosely held toner lying in areas not appropriate to its characteristics, excess toner falls off into 111, and is removed by ultrasonic transducer 109, and the remaining toner is transferred to preheated paper 113 which is then heated at 117 to fuse the image. Air doctor 121 removes any non- transferred toner, and erasing head 123 removes the magnetic image and leaves the member 101 uniformly magnetized. The magnetic pattern may be characters. Selective printing.-Polepieces 509, 512 (Fig. 5) are electromagnetically actuated by coils 508 to generate field in gaps 513 through which belt 101 is passed. Each pole piece is energized by a character pattern signal from 503 to which is superimposed an A.C. frequency 510 or 511 selected by switches 506.