Patent GB-587978-A (GB)
Title: Improvements in locking mechanism for the platen rollers of typewriting machines
IPC: B41J29/68
Filed: 1944-03-13
Abstract: 587,978. Typewriters. CAMZI, J. P. March 13, 1944, Nos. 4641 and 4643. Convention dates, March 15, 1943, and Nov. 2, 1943. [Class 100 (iv)] Locking devices ; alarms.-A device for indicating the number of lines remaining to be typed on a sheet and for preventing further rotation of the platen roller when the required number of lines have been completed, at which point an alarm may be operated, comprises an internally-toothed crown wheel coaxial with the platen and driven therefrom by reduction gearing, a stop member which can be positioned in any one of a series of peripheral notches in the crown, and a fixed stop in the path of the rotating stop so as to block further movement when the platen has moved through a predetermined angle of paper feed. In one form, Fig. 2, three discs 3, 4, 5, are freely mounted on the shaft 1 of the platen; the first-mentioned disc 3 being fixed to the carriage and having on its periphery a suitable scale and a fixed stop 15. The second disc 4 is formed internally with gear teeth by which it is driven from the shaft 1 at a reduced speed and in reverse direction through a pinion 6 on the shaft and an intermediate pinion 7 on the disc 3. The adjustable stop 13 is mounted on the disc 5 which is spring-pressed towards the disc 4 and is driven thereby by the engagement of a projection 12 on the stop with one of a series of recesses 11 in the periphery of the disc 4 spaced corresponding to line spacing. Thus after the stop 13 has been set, the numbers of recesses 11 between the stops 13, 15 indicates at any time the number of lines remaining to be typed and engagement of the stops prevents further rotation of the platen. In a modification of the arrangement shown in Fig. 2, the disc 21 carrying the scale and the fixed stop 41 are adjustably fixed to a member 25 by pins 23, 26, Figs. 6, 7 engaging holes 22, 27 respectively in the disc 21, and an adjustable indicator 32 is mounted on the disc to facilitate the setting of the movable stop 33. The later is carried by a disc 40 which is adjustably coupled by a projection 33a engaging one of a series of recesses 34 to a disc 45 geared by intermediate pinions to a pinion 42 on the platen shaft 20 so as to rotate in the same direction as the shaft. By means of a ballcatch 38, the disc 40 can be set either coupled to the disc 45 or uncoupled but with the stop 33 riding over the scale on the disc 21 or in completely disengaged position. The fixed stop 41 is mounted so as to be capable of slight movement against the action of a spring 47 when engaged by the movable stop 33, such movement being utilized to operate a hammer 51 to give an audible signal or, in the case of an electrically-driven machine, to open a switch. According to the Specification as open to inspection under Sect. 91 the scale and fixed stop 58, Fig. 15 (Cancelled), are carried by a fixed disc 53, and the movable stop 56 is coupled to a sleeve 54 driven by bevel gearing 55 from the platen shaft. This subject-matter does not appear in the Specification as accepted.