GB1009553A - Character-selection mechanism for serial printers - Google Patents

Abstract

1,009,553. Selective printing. SOROBAN ENGINEERING Inc. May 2, 1962 [June 12, 1961], No. 16880/62. Heading B6F. Type wheel machines; selection.-A character selection mechanism for a printing device comprises a character-bearing drum 19 and means for positioning the drum in relation to an impression hammer 18. The positioning means includes a shaft 9 which is rotated intermittently through a gear train 4, 6, 7, 8 from a continuously driven shaft 3, the gear 4 being eccentrically mounted on the shaft 3 so as to provide a short stationary interval after each 180 degrees of rotation of the shaft 9. The drum 19 is coupled to the shaft 9 for movement thereby by selectively operable coupling means comprising a mechanical motion summing device. The drum 19 carries 64 characters arranged in eight circumferential bands each of eight characters and is slidably mounted on a rotatable, splined shaft 102. Character selection is effected by simultaneous rotation of the shaft 102 and sliding of the drum on the shaft so that the chosen character is aligned with the hammer 18. Sliding movement of the drum is effected by the selective clutching to the shaft 9 of any one of or any combination of three pinions 21-23. The pinion 21 meshes with a gear 44 mounted on a shaft 46 which also carries an eccentric 47. A ring 48 rotatably mounted on the eccentric 47 carries an arm 49 on the lower end of which a pinion 51 is rotatably mounted, the pinion 51 meshing with vertically slidable racks 52, 53. The pinion 22 is connected in a similar manner to a pinion 54 which meshes with the rack 52 and with a further rack 56. The rack 56 is arranged for vertical movement through an arm 57, ring 58, eccentric 59, shaft 61, gear 62 and the pinion 23. The rack 53 also meshes with a pinion 69 mounted on a shaft 71 which carries a second pinion 72. The pinion 72 meshes with a rack 73 rotatably secured to the drum 19. Thus, when the shaft 9 rotates through 180 degrees the drum 19 is moved more or less to the left or right in accordance with which of the pinions 21-23 is or are clutched to the shaft. A similar arrangement controlled through pinions 29, 31, 32 effects rotation of the shaft 102, the final drive being through a rack 99 and a gear 101. pulse operation.-Each of the Clutching; pulse operation.-Each of the pinions 21-23, 29, 31, 32 has a hub 27, Fig. 3, which, in the position shown, is freely rotatable on the shaft 9. The hub 27 is formed with a longitudinal slot 28 and the shaft 9 has two diametrically opposed studs 24, 26 mounted one on each side of each hub. Each pinion is movable to the left or right from the position shown by means of a shifting fork 36 secured to the armature 34 of a pair of electromagnets such as 33, and is restored to the central position by a spring 38. When the parts are in the Fig. 3 position movement of the pinion 21 to the left (by energization of the left-hand magnet of the corresponding pair 33) results in the engagement of the stud 24 in the slot 28 so that when the shaft 9 is rotated the pinion is rotated with it. If the right-hand magnet is energized the pinion is moved to the right but is not clutched to the shaft as the stud 26 merely abuts against the hub 27. The drum rotating and sliding mechanisms are respectively controlled by means of three-bit binary codes, the bits of the codes being used to energize the pairs of electromagnets. Once a character has been selected, the selecting pinions do not need to be clutched to the shaft 9 in order to repeat the character, hence the opposite magnets of the pairs must be energized for the repeated character to those energized when the character was first selected. A variable reluctance pick-up 77 senses the angular position of the shaft 9, a coil 78 therein generating signals of different polarities indicative of the position of the shaft at any selection interval. The signal developed by the coil is used to determine which of the electromagnets of a magnetic pair is to be energized to indicate a one and which is to be energized to indicate a zero. In a modification, Fig. 5, the selecting pinions are replaced by members such as 119 rotatably mounted on sleeves 121 splined to a shaft 116 which corresponds to the shaft 9. Each member 119 has an eccentric portion 124 which actuates a ring 126 and an arm 138 which carries, for example, a pinion 139 corresponding to the pinion 51. Discs 117, 118 are secured to the shaft 116 and have holes 136, 137 in them. The member 119 is clutched to the shaft by the movement of a pin 128, slidably mounted in the member, to left or right by a pair of magnets 134. If the pin enters one of the holes 136 the member 119 is clutched to the shaft. Aligning for impression.-In the Fig. 5 embodiment the member 119 is formed with a double heart-shaped cam portion 122 on which a spring-biased roller 123 runs. This arrangement ensures accurate location of the drum 19 at the selected character. Hammer impression arrangements.-The hammer 18 makes a stroke at each stationary interval of the shaft 9 or 116. It is carried by a shaft 108 having an arm 107 rigidly mounted thereon. The arm 107 carries a cam follower 106 which is spring-biased into contact with a cam 104 on the shaft 3. When the follower 106 descends into a depression 114 in the cam the hammer is raised to make an impression, an ink-ribbon and a piece of paper or the like being interposed between the drum 19 and the hammer. The arm 107 may be locked by means of an electromagnetically operated detent 111 so that no hammer stroke is made when a space is desired instead of a character. Alternatively, the hammer may make a stroke at every cycle of the machine, being aligned with a recess in the drum 19 when a space is desired. Specifications 840,114 and 1,009,554 are referred to.