Patent GB-1045697-A (GB)
Title: Improvements in line feeding devices for printing apparatus
Inventor: MOORE FRANK ARTHUR
IPC: H04L13/06
Filed: 1964-05-20
Abstract: 1,045,697. Selective-printing apparatus. CREED & CO. Ltd. May 20, 1964, No. 20770/64. Heading B6F. Apparatus for feeding a printing medium D in steps through a printing machine, e.g. a teleprinter, which steps may be greater or less than or equal to a line space, comprises a roller 1 around which the medium D passes, ratchet- and-pawl means 7, 8 for rotating the roller 1, an input member 23 movable from a rest position in direction A and with a fixed throw to actuate the devices 7, 8, and an interposer 37 which in the rest position of the member 23 causes the pawl 8 to be moved clear of the ratchet wheel 7. In the rest position, the roller 1 can be rotated manually by a knob 49. An extension of the shaft 4 of the roller 1 carries the ratchet wheel 7 and the knob 49. A frame 12 is pivoted on the shaft 4 and one limb 16 thereof has a lever arm 20 with notches 21 on its upper edge, one of the notches being engaged by a pin 22 on the input member 23 and the particular notch engaged determining the extent of the feed step as described below. Another limb 11 of the frame 12 carries the pawl 8 which is spring-urged towards the wheel 7. Downward movement of the input member 23 effected, e.g. electromagnetically by a signal, causes a downward movement of the pawl 8 which movement releases the pawl from a tongue 40 holding the pawl away from the wheel 8 so that the pawl 7 engages the wheel 8 and rotates the roller 1. The tongue 40 is part of the interposer 37 which is pivoted on the shaft 4 and has an arm 38 pivoted by a pin 31 to a part 28 of a lever 24 pivoted on a fixed shaft 25. The pin 31 is engaged in one of a number of notches 21 in a pivoted arm 32, these notches corresponding to the notches 21 in lever arm 20. The arms 20, 32 are biased upwardly by springs 35, 34 respectively. At the end of the lever 24 opposite to that carrying the part 28 is a forked arm 30 engaging the pin 22, and also a key portion 29. Pivoted movement of the lever 24 in the direction E, effected by manual or electromagnetic operation of the key portion 29, causes the pins 22, 31 to be moved into the next adjacent notches 21. This causes (a) lengthening of the effective length of lever arm 20 and a decrease in the throw of the pawl 8 corresponding to one tooth of wheel 7, (b) a momentary movement of the frame 12 which brings the pawl 8 adjacent to the next lower tooth of wheel 7 and (c) a movement of tongue 40 to hold the pawl 8 away from the wheel 7 in the new position of rest. As described, with the pins 22, 31 engaged with the leftward notches 21 a feed of two line spaces is obtained corresponding to four teeth of ratchet wheel 7, and rightward shift of the pins effects a reduction of half a line spacing corresponding to one tooth of ratchet wheel 7 at each step. To provide for feeds of more than two line spaces, or less than one line space, additional notches 21 would be necessary. A roller 43 mounted on a spring-urged arm 41 engages the teeth of wheel 7 to hold the wheel stationary whilst the pawl 8 is inoperative. When the shaft 4 is rotated by the knob 49, the amount of feed movement imparted to the rollers is indicated aurally by the clicks made by the roller 43 as the teeth pass over it.