Patent GB-1297996-A (GB)
IPC: B41J2/41
Filed: 1970-03-09
Abstract: 1297996 Electrostatic selective printer XEROX CORP 9 March 1970 [10 March 1969] 11099/70 Heading B6F In an electrostatic printer, the drive mechanism for the carriage 60 carrying the printing head 58 has two modes of operation: a first mode which moves the carriage continuously to print out information received continuously from the output of electronic computers and telemetering receivers; a second mode which moves the carriage a character width at a time upon activation of a keyboard. Carriage guides and races; shock absorbing.- The carriage 60 is attached to a cylindrical piston type member 50 which slides in a guide tube 52 pivoted in bearings (not illustrated) at each end. The guide tube has a slot 200 (Fig. 3) extending along its underside for a major portion of its length, through which a radial extension of the piston 50 extends. Each end of the tube 52 is blind, except for small bleed holes (210, 207, Figs. 3 and 3A), so that as the piston 50 reaches each end, a dash-pot type dampening effect occurs. A solenoid 156 pivoted to a lever 157 attached to the tube 52, acts to pivot the type head 58 away from the paper web 54 for the "carriage return". The carriage 60 is moved by a belt 36 (or alternatively a cable) fastened to the piston 50, and wound on to and off a cable drum 30. Side-stop mechanisms; column printing.-The carriage 60 carries an interposer 62 which effects a plurality of reed switches 64, 66 and 68 by shunting associated magnetic field producing means 70, 72 and 74 respectively. As an alternative, a magnet could be substituted for the interposer 62, therefore eliminating the necessity of magnets 70, 72, 74. The switches are positioned to indicate the "-5", "0", and "80" column positions on the paper web 54, but additional switches may be positioned along the guide tube 52 for indicating additional column positions. Letter and line spacing drive mechanism.-A timing belt 12, driven by an electric motor 10, drives a pulley 14 coupled to the input of a one-revolution clutch 20, and a pulley 18 mounted on the input hub of a wrap down spring clutch 26. For continuous movement of the type carriage, an electromagnet (152, Fig. 4) is energized to cause engagement of the clutch 26. The output hub of clutch 26 is coupled to a gear 28 co-operating with an electromagnetically operated pawl 76, the cable drum 30, and a spring motor 32. The clutch 26 drives the type carriage in the direction of the arrow 61 and at the same time winds up the spring motor 32 which returns the carriage 60 when the pawl 76 is released from gear 28. For step by step movement of the carriage 60, an electromagnet (122, Fig. 5) is energized with the depression of a character key on the keyboard (104, Fig. 2), which results in a single revolution of the clutch 20. Coupled to the output hub of clutch 20 in a worm-gear 22 with a cut-out portion 24, which meshes with gear 28 coupled to the drum 30. In the stationary position, the cut-out portion 24 is aligned with the gear 28, thereby allowing the drum 30 to be driven by the clutch 26 or spring motor 32 when necessary. An encoder 34 is mounted on worm-gear 22 to break the column advance of the type carriage 60 into seven increments, five for character information and two for intercharacter spacing. The pulses produced by the encoder 34 are used to condition the character generator (108, Fig. 2) to emit character information at the proper time, compensating for the varying velocity of the printing head as it steps from one character to the next, thereby preventing distortion of the characters printed when using the keyboard as the input to the printer. For back-spacing, the pawl 76 is disengaged from the gear 28 by its electromagnet (78, Fig. 5). For line-spacing, a paper feed, one revolution clutch 80, coupled to pulley 14, is engaged upon energization of an electromagnet (126, Fig. 5). When engaged, the clutch drives a worm-gear 82 meshing with a gear 84 coupled to feed rollers 90.