1278807 Typewriters TOKYO ELECTRIC CO Ltd 4 Nov 1969 [4 Nov 1968] 53984/69 Heading B6F In a single drum typewriter, two power driven clutches, a space clutch 43 and an action clutch 44 (Figs. 4, 11 and 12) are provided to perform certain functions under control of certain of the typing and control keys. For example, the space clutch 43 advances the carriage 13 (Fig. 2) during character spacing, back spacing return and tab functions, whereas the action clutch 44 performs such functions as raising the type drum, causing operation of the space clutch 43 and effecting printing. Both clutches are of similar construction, each having a continuously driven ratchet wheel (48, Fig. 11) driven by an electric motor (60, Fig. 4) via cog belts (62, 63, Fig. 12). Downward rocking of a clutch control dog (55, Fig. 11) causes the clutch to complete one revolution. Type selection; case-shift; Fig. 1 (Figs 4, 5, 5A and 6).-To enable the type drum 12 to be raised to different levels, a bushing 87 is rotatably mounted in the carrier 13 and is slidably keyed to a shaft 82. A pair of spaced arms 88 fixed to the bushing 87 are connected by pin and slot connections 90 to a ring 91 on the type drum. Depressing type keys and the shift key causes the type drum to be raised different amounts. For this purpose, a hook member (93, Figs. 4, 5 and 5A) is pivotally connected at (94) to a cam follower (81) and is provided with two spaced shoulders (95 and 96), each of which is adapted to limit against either of two ears (97 and 98) on blocking levers (99 and 100) respectively. If the blocking levers remain in their illustrated position (Fig. 5A) against a stud (109), during a single revolution of the action clutch (44) and therefore cam (76), the cam follower (81) and shaft (82) would be allowed to rock until the shoulder (95) moves through one increment (a) and abuts ear (97), thereby raising the type drum to the uppermost row of type. The two ears (97 and 98) are selectively positioned to allow four degrees of movement of the cam follower (81) corresponding to the four rows of type on the drum. For selective rotation of the type drum, box cams 42, Fig. 1, are located in a helical series about a shaft 27 so that when one of the keys is depressed and its corresponding cam lever 38 is raised, the respective cam roller 41 will be forced towards the apex of the cam opening in its respective cam, thereby rotating the type-drum from its previous position to the new selected position. The shaft 27 carries a gear segment (29, Fig. 6) which meshes with a gear 28 on shaft 25 carrying bevel gear 24 meshingwith the bevel gear 23 of the type drum. Interlock and repeat action; Fig. 1. In order to prevent depression of two type keys, a bail 84 has a sharp edge 115 which normally lies directly opposite a corner 116 of each of the cam levers 38. The bail 84 will strike a surface 117 on the partly raised lever 38, thereby forcing the actuated lever through the remainder of its upward stroke. At the same time, the bail 84 will move over the top surfaces 118 on the remaining cam levers to prevent depression of the other keys. Also the bail 84 picks up the rear end of actuated interponent 65 to release shoulder 67 from the clutch engaging bail 70. This limits the clutch to one cycle even though the key is held depressed. However, with further depression of the key against added spring pressure, the shoulder 68 of the interponent additionally rocks the clutch engaging bail 70 to cause repeat action of the action clutch (44). An alternative is described with reference to (Fig. 15). Filter and line spacing; reversible drive; Fig. 1 (Figs. 9,10 and 12).-The type carrier 13 is screwthreaded on a screw shaft 133 which is connected to the driven side of the spacing clutch (43, Fig. 12) through a reversing unit (135). A cam (78) driven by action clutch (44), engages a follower (136, Fig. 7) attached to the clutch dog (355) of the spacing clutch. Following a print operation, the spacing clutch is engaged to rotate the screw-shaft 133 one-half revolution for one character space. The reversible drive (Fig. 12) comprises an annular slide member (158) coupled to a key (265) slidable in keyway (156). The slide member (158) is engageable by two-pronged shift member (161, Figs. 9, 10 and 12) which is pivoted on a frame pin (162), and which serves to shift the slide member axially. The inner end hub faces of gears (261 and 264) each have a series of teeth (164) alternatively engageable by opposite ends of the key (265). The two extreme axial positions of the key (265) defines the forward and reverse drives respectively of the screw-shaft 133, Fig. 1. Tabulating and margin stops; tab by action; Figs. 1 (2 and 4).-Settable tab stops 185 are slidably keyed to a rock shaft 186. Wire spring elements 187 engage any of a series of regularly spaced detent notches 188 in the shaft. Depression of tab key (190, Fig. 4) will rock clutch dog (355) to cause cycling of the shift clutch (43). At the same time, a spring (199) will rock arm (198) clockwise to latch clutch dog (355) under a shoulder 270 to cause continued cycling. Similar clockwise rocking of shaft 186 will locate the tab stops 185 in the path of a pin 200 fixed to the type carrier 13. Each tab stop 185 has a camming surface 210. When the pin 200 strikes the surface 210, the shaft 186 is rocked counterclockwise to release the space clutch dog 355 to disengage the clutch. Margin stops 213 with camming surfaces 215 are engaged by a pin 212 and act in the same manner to disengage the clutch. Platen impression; throat opening; Figs. 1 and (4)-The platen 14 is rotatably mounted at opposite ends in slide plates (Fig. 4) having slots guided over stationary guide pins (121). Each plate (120) is coupled to a lever (123) coupled to an arm (125) fastened to a rock shaft 126. The shaft 126 carries a cam follower 127 which co-operates with cam (77, Fig. 12) driven by the action clutch (44). A pressure roller 290 is rotatably mounted on a shaft 291 which is movable transversely along guide slots 292 to an open throat position. Aligning for impression; Fig. 1.-A centralizer arm 128 slidably keyed to the cam (77, Fig. 12) actuated rock shaft 126 engages any of a series of detent pockets 131 formed on the inner periphery of the type drum. Key actions other than type-selecting; tab key action (see above). The space bar is mounted on levers (141, Fig. 7) pivotally connected to a lever (143) pivotally connected to a hook (144) having a pair of shoulders (145) and (146) thereon. Normally, shoulder (145) engages a pin (147) on space clutch dog (355). To prevent repeat spacing if the space bar is held depressed at the normal depth, a cam (150) on the screw shaft 133, Fig. 1, rocks a pivoted interponent (151) to move the hook (144) and so release the pin (147). Repeat spacing is caused by further depression of the space bar so that shoulder (146) engages pin (147), this allowing the clutch to continue cycling since the throw of cam (150) is ineffective to remove the shoulder (146) from pin (147). The return and lock space key actions (Figs. 9 and 10) are similar to that of the space bar, but have additional second hooks (183 and 171) respectively, which operate the two pronged shift member (161) (see letter spacing etc. above) for reversing the drive. Depressing the line spacing key (220, Fig. 13) causes the intermediate portion of link (225) to move so that a notch (232) therein engages a pin (233) formed on the extension of bail 84 (Fig. 4). When the action clutch (44) cycles, bail 84 is rocked and causes the link (225) to move downwards, so that a pawl (230) incrementally advances the platen. Alternative Embodiment Hammer impression; type drum with movable type; (Figs 16 to 18).-The type drum (12a) is slidably keyed on the shaft 20 and carries in each type character location, a slug (320) having a type character (321) formed on its outer end and a detent pocket formed on its inner end. Each slug is held in the retracted position by a wire spring (323, Fig. 18). A combined centralizer and hammer (326) is slidably keyed to the cam (77) actuated rock shaft 126. Ink ribbon mechanism; Figs. 1 (2 and 3).-An endless ribbon 280 is guided around a rectangular guide frame 281 on the type carrier 13. To raise the ribbon to a printing position, rollers (285) (Fig. 3) are mounted on frame brackets 283 and rest in engagement with cams (286) keyed to shaft 82 which is rocked different amounts to selectively raise the type drum. The ribbon is incrementally advanced by one of a pair of re-inking rollers 287 formed of inkabsorbing material.