Patent GB-1075955-A (GB)
Title: Device for incrementing a rotatable member
IPC: B41J11/36
Filed: 1964-12-09
Abstract: 1,075,955. Typewriters &c. INTERNATIONAL BUSINESS MACHINES CORPORATION. Dec. 9, 1964 [Dec. 19, 1963], No. 50019/64. Heading B6F. Mechanism for intermittently rotating a member an adjustable amount, e.g. for rotating the platen of a typewriting machine a settable number of line-spacing steps, includes a follower movable along a guide, manually-operable means for coupling the follower to the member so that the follower moves along the guide as the member rotates, and a selector positionable in the path of the follower so that contact of the follower with the selector determines the extent to which the member is rotated. As described, a typewriting machine has a single printing-head, which is movable parallel to the platen 2 for letter-spacing. The paper-feeding devices are set so that after manual insertion of a sheet, the platen can be rotated step-bystep automatically to feed the sheet to the first line on which typing is to be effected. After typing of matter has been carried out in the normal manner, the sheet can be fed step-bystep automatically to the last line of the sheet ready for manual withdrawal. The devices include a lead-screw member 17, Figs. 3, 5b, surrounding the platen shaft 33 and having a helical groove 17b calibrated along its length to indicate line spaces. Moving along the groove 17b as the platen rotates to indicate the line of the sheet which is at the printing position is a follower 55 projecting through a slot 47b in a follower-guide 47 rotatable within the member 17. A clutch part 47a on the guide 47 engages a clutch part 46a on a member 46 when the latter, which is keyed to a shaft 45 fixed to the platen shaft 33, is moved rightwardly, Fig. 3. When the clutch 46a, 47a is engaged, the guide 47 rotates with the platen shaft 33 causing the follower 55 to move along the groove 17b. Movement of the clutch part 46a is effected by flexure of a flat spring member 44 having an opening 44a engaging a groove 46b in the member 46 and also having projections 48, 49 engaging grooves 41c in an endwise-slidable housing 41. Pins 42, 43 on the housing 41 engage cam grooves 17c, in the screw member 17. External teeth 17a are provided on the member 17. To initiate an automatic feed operation, a lever 24 is depressed and moves a pawl member 28 upwardly so that a lug 28a thereon engages one of the teeth 17a to rotate the member 17 slightly and so, through the cam grooves 17c, causes endwise movement of the housing 41, flexure of the spring 44 and engagement of clutch 46a, 47a. A step 28b on the pawl 28 engages over a part 22b of a slider pawl 22, referred to later, to retain the pawl 28 in the raised position. Also operated by the lever 24 is a link 31 engaging a lever 65 actuation of which causes engagement of a pawl 88, Fig. 5b, with a constantlyrotating ratchet wheel 87 so as to drive a cam 68 operating the line-spacing mechanism described below. The line-spacing mechanism continues to operate until pawl 28 is released, i.e in the present instance when the first typing line on the sheet roaches the printing line. This typing line can be determined by a transparent knob 16 rotatable on the screw member 17 by means of an internal thread 16b and having a spring tongue 56 extending into the groove 17. The knob 16 is rotated until the tongue 56 is adjacent to the screw marking corresponding to the required first line. External teeth 16a on the knob 16 are engaged by the afore-mentioned pawl 22 to hold the knob in the set position. When, during the automatic feed, the follower 55 reaches the tongue 56, it rotates the knob 16 a small amount, thus moving the pawi 22 to the left, Fig. 2, against spring action, and releasing the pawl 28 so as to restore parts 31, 65 and stop the line-feeding. Typing is now carried out normally, the clutch 46a, 47a remaining engaged and the follower 55 moving past the spring tongue 56. When this operation is completed, the operator again depresses the lever 24 and automatic feeding ensues until the last typing line on the sheet is reached. At this position the follower 55 contacts an abutment on another transparent setting member 19, 20 on the screw member 17. The parts 19, 20 have interposed springs 20b tending to press them apart so as to hold the member firmly on the screw member 17, it being necessary to press the parts towards one another when setting the member. As the follower 55 now moves forward it rotates the member 19, 20 and the screw member 17 together. The cam slots 17c then move the housing 41 endwise to its original position, thus flexing spring 44 in an opposite direction and releasing clutch 46a, 47a. At the same time, the tooth 17a engaged by pawl 28, moves the pawl to release it and thus cause uncoupling of the line-feeding mechanism. The follower guide 47 is connected to the screw member 17 by a coiled spring 53 which is wound up as the sheet is fed through the machine. When the last typing line is reached and the clutch 46a, 47a is disengaged, the spring 53 rotates the guide 47, thus causing the follower 55 to be moved along the groove 47b back to the starting position. Line spacing is effected by a pawl 74, Fig. 6a, engaging a ratchet wheel 35 fixed to the platen shaft, the pawl being pivoted to a lever 73 oscillated by a linkage 69, 70, 72 actuated by the cam 68. The cam 68 can be coupled to the constantly-rotating ratchet wheel 87, Fig. 5b, by actuation of the lever 65 when the operating lever 24 is depressed, as already described. Actuation of the lever 65 to cause one revolution of cam 68 and effect a single linespacing occurs when a key 90, which may also actuate the carriage return mechanism of the printing head, is depressed. A link 92 engaging an extension 65c of the lever 65 has a pivoted part 94 normally latched under a stop 96. Depression of the key 90 causes the part 94 to be freed from the stop 96, whereupon the link 92 is moved by a spring 98 to actuate the lever 65. A cam 99 fast with the cam 68 operates on a lever to restore the parts 65, 92 after one revolution. Single or double line spacing for each revolution of cam 68 may be obtained. For this purpose, a lever 79, Fig. 7a, has at its end, surfaces 79a, 79b, 79c, against one of which a stud 80 on the pawl 74 abuts in the rest position. In the normal position of lever 79, the stud 80 abuts surface 79b and single-line spacing occurs. When, however, the key 24 is depressed for automatic feed, a projection 24b thereon moves the lever 79 downwardly, so that stud 80 abuts surface 79a, thus causing a longer stroke of the pawl 74 to effect double-line spacing. Double-line spacing can also be obtained by manual operation of a lever 13 which causes tilting of the lever 79 to bring the surface 79c into operative position.