Patent GB-999716-A (GB)
Title: Improvements in or relating to ribbon feeding mechanisms
IPC: B41J33/36
Filed: 1964-05-21
Abstract: 999,716. Ink-ribbon mechanism. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 21, 1964 [May 31, 1963], No. 20949/64. Heading B6F. Feed mechanism for an inked ribbon wound on a pair of spools comprises first and second spindles 4 for mounting the spools, first and second drive means adapted to rotate the first spindle at different rates, and means to render operative one or the other of the drive means. Feeds; reversal arrangements; brakes; detachable carriers.-The mechanism which may be embodied in a machine having a single element type head, as described in Specification 873,920, comprises two ratchet wheels 1, 2, Fig. 1, carrying spindles 4 upon which ribbon spools can be mounted, the spools being enclosed in a detachable countainer 5. A pawl 8 which is oscillated once during each printing operation from a cam 15 on a print shaft 16 can be engaged with either of the wheels 1, 2 and constitutes the first drive used when an ordinary fabric ribbon is employed. When the ribbon has been completely wound on to the spool carried by the driven ratchet wheel a part 18 of a member 19 is moved into the path of the pawl so that during the next stroke of the pawl the member 19 is moved rearwardly and operrotes a two-position member 22 connected to the pawl by a spring 23 so as to swing the pawl into engagement with the other ratchet wheel. The second drive causes a very much smaller step-by-step movement of the ribbon arid is used with a plastic ribbon made, e.g. as described in Specification 965,517, with which printing can be effected from areas of the ribbon which overlap. This drive comprises a pawl 80 which engages the ratchet wheel 1 only, the ribbon being fed through the machine once only. The pawl 80 is operated by a rod 81 connected to a lever 47 pivoted at 48 and having a notch 50 engaged by a pin 58 on a slidable member 54. A lug 60 on the member 54 engages a U-shaped member 61 slotted to slide upon a shaft 65 and pins 66. An arm 70 on the member 61 rides upon a cam 69 on the shaft 65, the cam having a surface which rises continuously from a low point to a high point and then drops abruptly to the low point. A ratchet wheel 68 on the shaft 65 is turned through one tooth for each printing operation by a cam 72 on the print shaft 16 operating a pawl 73. Thus if, for example, the wheel 68 has twenty-four teeth, then the lever 47 and pawl 80 are oscillated once for each twenty-four printing operations, to move the ratchet wheel 1 through one tooth spacing, but the cam 69 causes continuous intermittent movement of the ribbon between such spacings. Selection of one or other of the feeds is effected through a lever 84 pivoted at 85 and urged in an anti-clockwise direction by a spring 86. A finger 90 on the lever 84 engages the pawl 90 to hold it in engagement with the ratchet wheel 1 and a link 82 pivoted to the lever engages the member 22 to hold the pawl 8 in engagement with wheel 2. When a casing 5 containing a fabric ribbon is inserted, the casing engages a cam surface 88 on the lever 84 and pivots the lever clockwise, causing the pawl 90 and link 82 to be moved to inoperative position. A plastic ribbon container, however, has an opening 92 fitting over the cam 88 so that the lever 84 is unaffected and pawl 90 is operative on wheel 1, and pawl 8 on wheel 2. The spool of the plastic ribbon which fits over the spindle 4 of the wheel 2 has no fin to engage the spindle slot 87, so that rotation of the wheel 2 serves merely to prevent slackness in the ribbon. Vibrator mechanism; multi-colour arrangements; ribbon shifts.-The usual ribbon guides 6, Fig. 2, can be operated so that (a) they can be moved upwardly into one of two positions if a two-colour ribbon is used; (b) they can be maintained in inoperative position if a stencil is to be cut; (c) the lift is gradually increased during a series of consecutive printing operations and then reduced to the minimum and the process repeated; and (d) they can be raised to a position which permits easy changing of the ribbon. Up and down movement is effected by a cam 42, Fig. 2, on the print shaft 16 engaging a lever 40 pivoted at 41 and having a slot 44 engaged by a pin 45 upon which rests one of the arms 25 carrying the guides 6. The position of the pin 45 along the slot 44 determines the amount of lift. The pin 45 is pivoted to the lever 47 which operates the pawl link 81, Fig. 1, so that with the pin 58 engaging recess 50 as already described, the pin 45 is moved in steps away from the pivot 41 during a number of successive printing operations thus gradually increasing the lift and then the parts return to their original position. The member 54 carrying the pin 58 is, however, manually adjustable so as to move the pin into engagement with one of three other notches 51, 52, 53. In either of these positions, lug 60 is clear of the member 61 so that no progressive movement of the lever 47 and support pin 45 occurs. The notches are of such depth that notches 51, 52 cause lifts corresponding to the parts of a two-colour ribbon, and notch 53 does not cause any lift. For replacing a ribbon, lift is effected by a manual lever 33, Fig. 2.