Patent GB-202456-A (GB)
Title: Improvements in typewriters for the use of the blind
IPC: B41J3/32
Filed: 1922-06-20
Abstract: 202,456. Matthewson, E. G. June 20, 1922. Machines for braille type.-Relates to improvements in the machine described in Specification 3292/94 and comprising a set of keys for embossing characters in a sheet of paper secured by means of plates 1, 2 to a drum 40 which is rotated and moved axially for letter-spacing and line-spacing respectively, the rotating-mechanism comprising a ratchet-wheel 10 co-operating with a holding-pawl, and a driving- pawl which is carried by a keyoperated rocking-frame 41. Margin mechanism.-The drum 40 is automatically rotated at line-end, to carry the plates 1, 2 past the embossing-points, by means of a spring- actuated rocking-plate 14 provided with a roller 12 engaging a spiral cam 11 on the drum. The plate is secured to a sleeve 15 which carries the actuating-spring 16, and can slide and rock on a rod 6. On operating the character-keys or spacing-key, the drum is rotated by the driving-pawl, and the roller 12 rides up the cam until line-end approaches, whereupon, on release of the keys, the roller rides down a slope a on the cam and imparts a feed-movement of four letterspaces to the drum. At the next operation of the keys, the roller is lifted out of a notch b at the bottom of the slope, by means of a pin 20 secured to the rocking-frame 41 and engaging a slot 21 in the rocking-plate. The rocking-frame may be constructed with spring box-ends 42. Line-spacing mechanism.-When a line has been written, the drum 40 is automatically moved axially for line-spacing by means of escapement mechanism provided on the rocking-plate 14, described above, and comprising a pawl 22, pivoted on a rod 24 on the rocking-plate, and a gap 22a in the rocking plate, the pawl and gap co-operating with a stationary rack 5. The rack consists of a pivoted angle-bar which is formed on the edges with two sets of teeth of different pitch, and can be rocked by means of a handle 8, Fig. 1, to bring either set of teeth into position, a spring 9 retaining the rack in adjusted position. When the drum is in line-commencing position, the gap registers with the rack, and the pawl engages a tooth of the rack and prevents a propelling-spring 30 from moving the drum. During the upward movement of the rocking- plate, the rear edge of the gap engages the rack, and the pawl is released and raised by a spring 27, so that when the rocking-plate descends and again brings the gap into register with the rack, the pawl engages the adjacent tooth of the rack and permits a one-tooth movement of the drum. For manually line-spacing the drum when a complete line has not been written, the rocking-plate can be raised by means of a knob 13, to disengage the part 14a of the rocking-plate from the rack, a wing 23<a> of the pawl then permitting a one-tooth movement of the drum. The propelling-spring 30 is connected to a pulley 44 engaging the bight, of a cord 29 which is connected at one end to a standard, and at the other to a bracket on the rocking-plate 14. Sheet-clamping ar?,aizgetiteals.-The sheet is secured at the edges to the plates 1, 2 on the drum 40, the plate 1 being folded and provided with teeth, and the plate 2 carrying a hinged clamp 3 which is provided with teeth and is engaged by springs 4.