GB1142315A - Electrostatic printing machines - Google Patents

Abstract

1,142,315. Printing apparatus. G. RITZERFELD. 2 May, 1966 [26 May, 1965], No. 19156/66. Heading B6C. [Also in Divisions G2 and H5] A developed electrostatic image is fixed on copy material in the case of an electrophotographic apparatus Fig. 1 (not shown), or in apparatus using an electrostatic master, Fig. 2 (not shown), by a field generating device which has a frequency above 400 kc./s. and preferably greater than 1 x 10<SP>7</SP> c/s. In one embodiment, a developed image is transferred by a corona device 13, Fig. 3, to a web 12, and fixed by rod electrodes 17, 18 connected to a high frequency generator 19. In another embodiment, Fig. 5 (not shown), the transfer and fixing steps take place simultaneously by means of a bar electrode (24) connected to a direct voltage source (25) and a high frequency generator (19). A microwave radiation device 29, Fig. 7, having a high frequency radiator 30 has inner and outer conductors 31, 32 within a reflector 34 which forms a beam aperture 28. A metallic reflector 35 concentrates the beam over the width of web 12. The reflector (34), Fig. 8 (not shown), forms a counter electrode for producing a direct current potential to cause image transfer simultaneously with fixing. In modifications reflectors (36), Fig. 9 (not shown) and (45), Fig. 10 (not shown), of dielectric material are used, e.g., phenol or polyester resin with mica. An intermittent feed of web 12, Fig. 11, to reproduce selected lines is under the control of a switch 53 which controls the bias of valves 51, 52. In the position shown, the grid of valve 51 has no bias, thereby producing a voltage at resistor 54, such that a sufficient potential exists between cylinder 2 and roller 58 to prevent the transfer of powder to the web 12. A plate 57 which has a high positive voltage attracts negatively charged web 12 so that the web is held by the plate while the roller 58 rotates. Image transfer and web feeding is resumed when the switch 53 is moved to the left. A particular line may be printed under the control of cams (66, 67, 68), Fig. 12 (not shown), which rotates in synchronism with cylinder 2 to produce pivoting of a microwave radiator 91 and roller 56 towards the cylinder 2 to effect transference and fusing of the power image. Alternatively, an electromagnet (83), Fig. 13 (not shown), controls the pivotal movement of a feed roller 56 towards and away from cylinder 2.