GB1141587A - Keyboard operated printer - Google Patents

Abstract

1,141,587. Typewriters, &c. INTERNATIONAL BUSINESS MACHINES CORP. 1 Aug., 1967 [14 Sept., 1966], No. 35210/67. Heading B6F. In a keyboard-operated printer comprising printing means such as printing head 12 and a platen 11 movable relatively for character spacing, and wherein operation of a character key sets storage means e.g. an interposer 25 which selects and controls the printing of the character, means are provided whereby if a character key is depressed whilst a control means causing relative movement of the printing means and platen for carriage return or tabulation is operative, the storage means is prevented from effecting printing until the relative movement is completed. Depression of a character key such as 21 or 22 depresses an associated interposer 25 to release the latter from a latch spring 25a whereupon a spring 25b moves the interposer rightwardly beneath the latch 25a to a storage position. Normally, a cyclicallyrotatable shaft 26 is now operated to move the interposer leftwardly and during such movement the interposer acts upon bails 25c which through mechanism 30 effects character selection, printing and letter spacing escapement operation. Rotation of the shaft 26 and power driving of the mechanism 30 is accomplished through a cyclically-operable spring clutch 40. The clutch 40 is rendered operative by leftward movement of a link 42 under the action of a spring 44. Such movement is normally prevented by the engagement of a latch 43 on the link 42 with a stationary frame part 14, but downward movement of an interposer 25 depresses a bail 28 which releases the latch 43, so that link 42 moves leftwardly and operates the clutch 40 to initiate a printing cycle. A ball interlock 29 is provided which prevents the simultaneous presence of two interposers 25 in the storage position but permits the movement of an interposer to storage position whilst a previous set interposer is operating to effect printing. Carriage return.-Character-spacing movements of the type-head carriage 13 are effected under control of a conventional escapement mechanism by a spring 54 through a capstan 53 and cord 51. For carriage return a key 23 is depressed causing, through mechanism 60, energizing of a motor 55 which drives the capstan 53 so as to return the carriage 13 and wind up the spring 54. A shaft 61 is rotated anti-clockwise by the mechanism 60 to a position where it is retained by the engagement of an arm 62 thereon with a latch 63. Near the end of the return movement a carriage stop 65 engages a stop 64 on a margin rack 66 and moves the rack leftwardly. The movement of the rack 66 operates to release the latch 63 through a bell-crank 68 so that the shaft 61 returns to its initial position and the motor 55 is stopped. Tabulating.-Depression of a tabulation key 24 causes release of the carriage escapement so that the carriage 13 moves freely under the action of the spring 54 until a sensing finger 72 on the carriage engages a pre-set stop. 71. The finger 72 is on a member 73 pivoted by a pin-andslot 74 to the carriage 13 and normally held by a spring 75 in the position shown where the finger 72 is out of alignment with stop 71. Lugs 73a, 73b on the member 73 engage a torsion bar 76 which, when the key 24 is depressed, is rotated and pivots the member 73 about the pin 74 so that finger 72 is now aligned with the stop 71. A catch 77 holds the member 73 in this position until the finger 72 engages the stop 71 whereupon the member 73 is moved leftwardly and clear of the catch 77 so that the parts 73, 76 can return to normal positions wherein control of the carriage 13 by the escapement is restored. Interlock between the carriage return or tabulating mechanism and the printing mechanism.- Means are provided to prevent movement of link 42 to initiate a printing cycle after an interposer 25 has been moved to a stored position, if a carriage return or tabulating action is taking place, but allows printing to take place when the action is completed. A finger 80 attached to a shaft 81 is normally held by a spring 82 clear of a shoulder 45 on the link 42. If, however, a carriage return movement is initiated, the anticlockwise rotation of shaft 61 actuates a link 69 to rotate shaft 81 and move the finger 80 into the path of shoulder 45 so that the link 42 cannot complete an operative stroke until the carriage return is completed and the parts 61, 69, 80, 81 are restored to their normal positions. Similarly, if a tabulating movement is initiated, a link 79 connected to the torsion bar 76 operates the shaft 81 and finger 80. The shaft 81 is mounted in slots 85 so that if a carriage return or tabulation operation is initiated prior to the full restoration of the link 42 from a previous cycle, and the finger 80 strikes the bottom of the link 42, the shaft 81 can move bodily to prevent damage.