GB1145106A - Apparatus for electrostatic printing - Google Patents

Abstract

1,145,106. Selective electrostatic printing; feeding webs; printing and duplicating processes; sheet delivering apparatus. BORGWARNER .CORP. 27 June, 1966 [26 July, 1965], No. 28758/66. Headings B6B, B6C, B6F and B6H. [Also in Division G2] Type-band machines; electrical input arrangements.-An electrostatic printer is provided with a charging head 215, Fig. 5, which is controlled for character selection by a control unit 214, associated with a computer line-by-line buffer store to produce latent images on a record web 120 through character defining apertures 227 in an endless character mask 216 in synchronism with timing apertures 225 sensed by a photo-electric sensor 224, 226 to gate on the charging head 215. Web feeding, guiding and tensioning arrangements.- Record web 120, Fig. 4, is supplied to the electrostatic printer from a roll 101 mounted on a shaft 102 which is associated with a brake 103, a motor 130 driving a pair of nip rollers 125, 124 through a clutch 127 to form a loop 144 disposed between three sets of photo-electric sensing units 145, 146; 147, 148 and 150, 151. When the loop is disposed between the sensing unit 145, 146 the motor the clutch 127 is disengaged and web feeding interrupted by application of the brake 103. The loop of record web is reduced by the feeding mechanism of the electrostatic printer which includes nip rollers 243, 244, Fig. 5, and when the loop becomes withdrawn above the level of the sensing unit 147, 148 the clutch is re-engaged and the brake released. A break in the web is indicated by a sensing unit 150, 151 which stops the feed and sounds an alarm and/or actuates a warning light 915 (Fig. 1). Low web condition is sensed by a feeler 106, Fig. 4, having a web diameter sensing arm 112 and an arm 114 which actuates a micro-switch 116 to operate a warning light 911 (Fig. 1). The web is spliced over a pivotal table 122 provided with registering pins 153 and a registration groove 154. Improper splicing e.g. excessive thickness of web splice which may jam in the printer is indicated by a feeler 133 scanning the surface of the web and actuating a micro-switch 188 in the case of a fault. The loop 144 of record web 120 forms a buffer store for the electrostatic printer in which the web is advanced by nip rollers 243, 244, Fig. 5, which are actuated intermittently by solenoid 246 in response to control signals generated by a timing disc 237 and associated photo-electric sensing unit 238, 240, 241 which also actuates marginal brake assemblies 205, 206 in an alternating mode with respect to the nip rollers 243, 244. The latter advance the record web through the printer to form a second loop 254 depending from a stationary guide 253 and controlled by " stop " and " start " photo sensing units 257, 258 and 260, 261, respectively. Developing and fixing of latent electrostatic images; electrostatic ink deposition.-The charged record web 120 is drawn off the storage loop 254, Fig. 5, into an inker station 300, Fig. 6, over a guide roller 301 and anvil 306 forming part of an ink reservoir 369 which contains a constant head of dry ink powder 307 whose excess overflows through a duct 352 into a hopper 333 from which the dry ink powder 307 is recirculated by a Venturi ejector 331 and a line 335 into a cyclone classifier 337 in which the fine fraction is removed through an outlet duct 338 and the coarser fraction is discharged on to the vibratory screen 348 of a second classifier 347. Unwanted fraction retained by the screen is removed through a slot 356. Residual fraction is supplied through duct 351 into the ink reservoir. Excess ink powder adhering to the web passing over the anvil 306 is removed by a suction nozzle 313. The developed record web 120 is passed into a fixer station 400, Fig. 7, comprising a pair of nip rollers 401, 410, the latter being mounted on a pivotal bracket 412 which is displaced into the phantom position to facilitate threading of the web. The roller 401 is driven by a motor 508 through a clutch 406 which is energized or de-energized by respective photo-sensing units 424, 425 and 422, 423 sensing the state of the storage loop 421 drawn off into a cutting station 500. Sheet delivering and cutting apparatus.- The developed and fixed recording web 120, Fig. 8, is delivered from the fixer station 400 into the cutting station 500 by endless tractors 506 and a guide roller 502, the cutter blade 517 which co-operates with a stationary blade 516 being driven in synchronism with the endless tractors 506 and actuated by signals generated by photo-sensing unit 511, 512 which scans the recorded marks on the web which correspond to the cutting lines. The cut sheets are delivered by further endless tractors 526 either to a solvent applying station 600 or to a sheet stacking station by an endless pin feed chain 602, Fig. 9, where the sheets are deposited on a platform 802 on which they are aligned by a pivotal arm 804 having a stop 805. The platform is lowered intermittently by a chain 814 driven by motor 812 whenever the stacked sheets raise the arm 804 sufficiently for an associated lever 806 to actuate a micro-switch 808. When the stack is lowered sufficiently for the lever 806 to disengage lever 807 of micro-switch 808 the motor is stopped. An arm 816 depending from platform 802 actuates two leader connected micro-switches 818, 823 to sound a warning or actuate a light 920 (Fig. 10) indicating a full stack. Duplicating arrangements.-The developed record web is cut into master sheets which are then advanced by the pin feed chain 602, Fig. 9, into contact with a solvent applying roller 611 which is supplied with the solvent for the fixed dry ink powder on the master sheets by a doctor blade 626. The latter is spaced from the applicator roller 611 by the thickness of the film by a spring 630. The solvent is supplied to the doctor blade from a reservoir 614 by a pump 616 through respective conduits 615, 625. Solvents for the dry ink powder which contains soluble hydrocarbons include trichloroethylene, toluol or xylene. The wetted master sheets are advanced by the chain 602 over further rollers 620, 621, 622 into the duplicating station comprising a fixed rubber-covered impression roller 701 -and a reciprocating transfer roller 28 mounted on a bracket 713 which is biased into its inoperative position by springs 715 and actuated into its operative position by an hydraulic piston (in an hydraulic cylinder 31) in response to operation of an hydraulic valve 703 which is actuated by a cam 702 coupled to the impression roller. The transfer roller 28 presses zig-zag folded stationery 717, fed by endless pin feed tractors 705 over the roller 28, into contact with the master sheets. Tensioning of the stationery is effected by brushes 725, which when the in-fed stationery breaks, contact the arm 728 of a switch 727 to produce an alarm signal. A break in the reproduced stationery is detected by a similar switch 732. Absence of stationery 717 in the stack 718 is signalled by a switch 721 whose sensing finger is in contact with the lower surface of the stack.