Patent GB-982774-A (GB)
Title: Ribbon feed mechanism
IPC: B41J35/14
Filed: 1963-06-24
Abstract: 982,774. Ink-ribbon mechanisms. INTERNATIONAL BUSINESS MACHINES CORPORATION. June 24, 1963 [June 26, 1962], No. 24955/63. Heading B6F. An inked ribbon feed mechanism for a synthetic plastic or fabric ink ribbon comprises a ribbon guide 156, Fig. 2, movable in the plane of the ribbon in a direction transverse to the longitudinal feed to position the ribbon for print action by a print element, a rod 61 movable in a slot 60 of a pivotal member 57 on each print action to vary the amount of transverse movement to the guide 156 and a means including a member 91, Fig. 1, operated by cam 78 via a pin 95 and an end portion 94 of the member 91, after a predetermined number of print actions, to advance the ribbon a predetermined distance longitudinally. Vibration mechanism. (a) Successive strokes variable; ink ribbon guides. A synthetic plastic ink ribbon is used once only and the ribbon is displaced transversely to twenty-two different .positions relative to the type elements before it is advanced longitudinally. The ink ribbon is stretched between guides 156, Fig. 2, which are attached to upper and lower arms 55, 42 the latter being lifted during each print action by a rod 61 moving slidably in a slot 60 of a cam-follower 57 pivotally attached at 58 and engaging a cam 59 on a shaft 17, which executes one revolution for each print action. The successive raising of the guides 156 up and down vertically is determined by the position of the rod in the slot 60, maximum lift corresponding to the rod being in the extreme left-hand position, in Fig. 2, and minimum lift corresponding to the rod overlying the pivot 58. Sliding movement to the rod 61 is imparted through a lever 64, pivoting about a pin 65, Fig. 1, by an end 75 of a lever 74, which engages a pin 76 on the lever 64. The lever 74, which is pivotally mounted on the pin 65 is provided with a camfollower 77 co-operating with a cam 78 fast with a ratchet wheel 80, which receives incremental movements by a dog 96 on a lever 97, Figs. 2 and 3, having a cam-follower 99 engaging a cam 20. The ratchet wheel is driven one tooth on each rotation of the shaft 17 to thereby displace the cam 78 and end portion 75 accordingly, the latter either positively displacing the rod 61 towards maximum lift or permitting the rod to swing under the action of a spring 62 to minimum lift. When the cam 78 reaches a position in which a stud 95, Fig. 1, thereon engages the end portion 94 of the member 91 pivoting about 92, the member is pivoted to engage its hooked arm 90, Fig. 3, by the tail 88 of a latching pawl 35 to raise the pawl sufficiently for a projection 37 of a member 21 to engage projection 38 of the pawl 35. Subsequent movement of the cam 20 displaces the member 21 which rocks a feed pawl 5, Fig. 4, to drive a ratchet sheet 2 for the ribbon spool a distance of one tooth space. As the stud 95 slides off the end portion 94 the member 91 rocks to release the pawl 35, whose shoulder 39 engages projection 37 of the member 21 to hold it away from the cam 20 until a further rotation of the cam 78 is completed. (b) Successive strokes constant; shifts to expose writing.-When using a fabric ink ribbon the variable stroke vibrator movement is disabled by clockwise movement of a lever 85, Fig. 1, resulting in disconnecting of the cam-follower 77 and end portion 75 of the lever 74 from the cam 78 and pin 76 and also in the engagement of an arm 101 of a portion 112 on the member 91, which is pivoted clockwise to remove end portion 94 out of engagement with the pin 95 and latch the pawl 35, Fig. 3, which is pivoted clockwise by the hooked arm 90 on the member 91 engaging the tail 88 of the pawl. The sliding member 21 is now free to engage the cam 20, which displaces the member on rotation once every print action to rock the pawl 5, Fig. 4, and drive one or the other of the ratchet wheels 1 or 2 two tooth spaces. The ribbon may be selectively raised or lowered manually by operation of a handle 70, Figs. 1 and 2, on a lever 68 having a pin 71, which co-operates with three detents 66 on the lever 64, the detents corresponding to high, medium and low ribbon lift, the ribbon being lowered each time to expose the typing. Automatic ink-ribbon reversal.-The fabric ink ribbon is reversed automatically, when the ink ribbon has been wound completely on to the driven spool by an arm 7, Fig. 4, on a member 6 positioned in front of one of two upturned flanges 8 on a pivoted toggle member 10, which has a downturned flange 114 connected by a toggle spring 11 to the pawl 5. As the member 6 is moved rearwardly, the toggle member 10 is pivoted and the spring passes overcentre to swing the pawl 5 into engagement with the other ratchet wheel. Stencil cutting.-When the typewriter is being used to cut stencil the member 21, Fig. 3, is held free of the cam by a pawl 36 whose projection 40 engages the projection 37 of the member 21 so that no feeding of the ribbon takes place. The lever 74 is disabled as described under vibrator mechanism with successive strokes constant, the arm 68, Fig. 1, is swung into an extreme counterclockwise position so that the rod 61, Fig. 2, is displaced beyond the pivot 58, to the extreme right, and a cam portion 116, Figs. 1 and 3, on the arm 68, moves away from a tail-piece 117 on the latching pawl 36 to enable it to drop into its operative position. Changing ink ribbons.-When changing from one type of ink ribbon to another, i.e. from a synthetic plastic one to a fabric one it is desirable that the member 21, Fig. 3, be released from the pawls 35, 36 so that the pawl 5 is free of the ratchet wheels that it may be moved transversely into driving relationship with any one of the ratchet wheels 1 or 2, Fig. 4. For lifting of the pawls 35, 36 when the ribbons are being changed the pawls are provided with hooked portions 120, 121, Fig. 3, respectively, engageable by a flange 44 when the ribbon guides 156, Fig. 2, and lift arms 42, 55 are raised by manual actuation of a member 47, which displaces a bifurcated arm 46 against a finger 45. A stop-pin 53 limits the swinging of the member 47 in either direction. Specification 883,818 is referred to.