Patent GB-1203394-A (GB)
Title: Selective printer
IPC: H04L13/18
Filed: 1968-04-10
Abstract: 1,203,394. Selective printing. S.C.M. CORP. 10 April, 1968 [24 April, 1967], No. 17210/68. Heading B6F. A telegraph printer 20, Fig. 1, having an axially fluted, rotatable, character forming cylinder 27, whose ribs 38 co-operate with a hammer 43 to print characters in the form of an array of dots in response to character representing signals fed to the printer, is provided with a carriage 64, Fig. 5, for the hammer 43, the carriage which is guided on a bar 26 and a shaft 65 being driven in letter-spacing direction by a threaded lead screw 93 driven by a single revolution clutch 113, Fig. 9, to displace the carriage a small increment corresponding to a single signal bit or a number of consecutive signal bits. Each time one or more signal bits are applied to the printer the clutch is energized and the lead screw 93, which in addition to driving the carriage also drives the cylinder 27 through gears 106, 108, is rotated so as to displace the rib 38 in front of the hammer 43 angularly relative to the face 42 of the hammer which is actuated by a spring 84 into impact with a printing medium R, the time of contact with the recording medium being controlled by a restoring electromagnet 75 whose armature 82 is integral with the hammer. The hammer is actuated repeatedly or allowed to dwell as the cylinder 27 rotates depending on whether dots or vertical strokes are called for in the formation of a character. The impression of the hammer is adjustable by a set screw 85 which varies the compressive force of the spring 84 biasing the hammer for impression. Restoration of the hammer carriage 64, Fig. 5, to the line starting position is effected by applying an electric signal to a carriage return electromagnet 158, Fig. 1, which attracts its armature 155<SP>1</SP> to release a lug 154 on a lever 150 mounted pivotally on the shaft 65 and biased upwardly by a spring 153. The lever 150 has a pin 172 which rotates a latch 170 fast with the shaft 65 to rotate the latter, Fig. 4, whereby a nose 97 extending axially along the shaft 65 and forming part of an axial groove 95 in the shaft, releases the arm of a fulcrum lever 90 to disengage a threaded segment 92 on the distal end of the lever 90 from the lead screw 93 and allow the carriage 64 to be returned by its spring 177. As the carriage is returned a stop 182 strikes a latch member 174 which releases the latch 170 so that it can pivot downwardly under the bias of its spring 173 into contact with the abutment pin 172 and thereby rotate the shaft 65 and re-engage the threaded segment 92 on the fulcrum lever 90 with the lead screw 93. Noise suppression arrangements.-Subsequent to the stop 182, Fig. 4, striking the latch member 174 as the carriage 64 is returned to its line starting position a guide bushing on the carriage and moving along the shaft 65 strikes a rubber buffer 181 to cushion the driving force of the carriage return spring 177. Line-spacing arrangements; web feeding and guiding arrangements.-A printing medium R, supplied from a web roll R<SP>1</SP> Fig. 1, and guided over an arcuate guide 45, is fed at line-spacing intervals by a pair of axially spaced rollers 46, 47, Fig. 9, mounted freely rotatably on eccentric bearings 28, 29 such that the peripheries of the cylinder 27 and the rollers 46, 47 are co-tangential opposite the hammer 43 to permit of a line contact only between the printing medium R with the cylinder 27. The rollers 46, 47 are provided with friction surfaces in contact with pressure rollers (54, 55, Fig. 7) mounted on respective fulcrum levers (53). The rollers 46, 47 are fast with respective gears 60, 61 which mesh with gears 62, 62<SP>1</SP> mounted on a shaft 63 one end of which supports a ratchet wheel 163 indexed by a pawl 162, pin-and-slot connected to and pivotally mounted on the lever 150 which is imparted a single oscillation by a cam 107, Fig. 1, fast with the lead screw 93. The electromagnet 158 is de-energized prior to the downward displacement of the lever 150 by the cam 107 and before the carriage return is completed such that the lug 154 may be arrested by the armature 155<SP>1</SP>.