Patent GB-988920-A (GB)
Title: Counter mechanism
IPC: B41J29/13
Filed: 1963-11-21
Abstract: 988,920. Linkwork; ratchet mechanisms. NATIONAL CASH REGISTER CO. Nov. 21, 1963 [Nov. 27, 1962], No. 46013/63. Headings F2K and F2Q. [Also in Division G4] In a selecting and driving mechanism, e.g. for an item counter in a data entry machine, including a lever 507 pivoted at one end by a stud 564 to a pawl carrier 509 and at the other end by a shaft 503 to a driving member 506, and having a stud 508 intermediate its ends, a finger 502a of a selecting plate 502 may selectively be positioned beneath the stud 508 to form a fulcrum for the lever 507 so that a cam induced downward movement of the driving member 506 causes an anticlockwise (Fig. 2) rotational movement of the pawl carrier 509 about a shaft 512 on which it is rotatably mounted, and the selecting plate 502 has a multi-faced, e.g. hexagonal, aperture by which it is mounted on a shaft 501 of corresponding cross-section, the centre line of the finger 502a being angularly offset, e.g. by 15 degrees, from a shaft radius normal to the aperture face adjacent the finger. A data entry machine includes a series of item counters 538, mounted on a removable sub-frame 556, each comprising three wheels 539 peripherally numbered 0-9 and rotatably mounted on the shaft 512, each wheel being secured to a ratchet wheel 557 engaged by a spring-loaded backrunning stop 569. In each counter 538, a pawl 558 having staggered tines 558a is pivoted on a stud 564 on a pawl carrier 509 which is urged clockwise (Fig. 2) by a spring 559. A deep notch 567 in each wheel 557 at the zero position of the associated wheel 539 acts with the staggered tines 558a to produce the tens and hundreds transfer operations. The shaft 503 extends the full width of the series of counters 538 and is engaged at its ends by two arms 506 which are reciprocated vertically at each operation of the machine. A selection shaft 71 is geared to the shaft 101, which also extends the full width of the counters, by gears 567 and 573, the selection plates 502 being mounted, one for each counter 538, on the shaft 101 in various angular positions. In operation, when the arms 506 are depressed, where the finger 502a is not beneath its stud 508, the lever 507 pivots about its stud 564 and the counter is not actuated, while where a finger 502a is beneath its stud 508, the lever 507 pivots on the finger so that the corresponding pawl carrier 509 is moved anticlockwise (Fig. 2) to cause its pawl 558 to advance the counter one step. To zero the counters, the shaft 512 is rotated manually, pawls (not shown) in the wheels 539 engaging a longitudinal slot 513 in the shaft, so that all the wheels are returned to zero. Fig. 3 shows a cam arrangement for locating the zero position accurately. A cam follower 516 and a bell-crank 519, both pivoted at 579, are urged anticlockwise (Fig. 3) by springs 583, 589 respectively. As the shaft 512 is rotated, the follower 516 is forced out of a notch 515a in a cam 515 on the end of shaft 512, causing a stud 518 on the follower to pivot the bell-crank to bring a notched end thereof into the path of a stud on the cam 515, so located that the stud abuts the notched end at the zero position of shaft 512. A small reverse rotation is necessary to release the stop and reset the linkage.