GB1346647A - - Google Patents

Abstract

1346647 Selective printing XEROX CORP 11 June 1971 [15 June 1970] 27432/71 Heading B6F Electrostatic printing apparatus employs a pair of reciprocating print head assemblies (30, 32, Fig. 2), one of which traverses the entire print field in a record mode while the other one moves in the opposite direction in an inoperative mode. The print head assemblies are supported respectively on parallel spaced apart guide rails (34, 36) so that the recording styli of each, prints along the same line relative to a moving recording web. However, means is provided for moving the non-recording styli out of the path of travel of the recording styli as well as disengagement from the recording web. Each print head assembly comprises a base member 60 adapted to reciprocate along guide rail (34) or 36, a frame member 68 pivoted to the base member on an axle 65, and a recording styli holder 70 pivoted to the frame member on a shaft 72. Springs 100 and 94 bias the recording styli 78 into engagement with the web 16 passing over a back-up electrode 81. An endless cable 152 passing round two pulleys, one of which is driven by a reversible motor (54, Fig. 2), has both print head assemblies clamped thereto by way of bar 84 with a set screw 86. The bar 84 is mounted on a yoke (106) pivoted at (108, Fig. 5) to the base member 60. An end 88 of bar 84 acts as a cam and engages a cam follower 90 forming an integral part of the frame member 68. When the drive of the cable is reversed for carriage return the cam 88 engages the inclined surface 92 of the cam follower 90, and in so doing depresses the frame member 68. The holder 70 thereupon moves down to engage an adjustable stop 98 on the base member 60, and in so doing is pivoted with respect to the frame member 68. For carriage return, therefore, the recording styli 78 are positioned out of the path of the recording styli on the other print head assembly. The other print head assembly is a mirror image of the first assembly.