Patent GB-525985-A (GB)
Title: Improvements in or relating to printing mechanism
Filed: 1939-03-04
Abstract: 525,985. Typewriters. BRITISH TABULATING MACHINE CO., Ltd. March 4, 1939, No. 7176. Convention date, March 5, 1938. [Class 100 (iv)] In a printing mechanism in.which printing impressions are effected without interrupting the rotation of the type-wheel, at various points in a cycle of the mechanism, the type wheel is mounted on a carrier which rocks it towards the platen for impression and which is mounted on the same shaft as the gear wheel which meshes with the type wheel for type selection. A type selecting clutch connects the gear wheels to a cyclically operated driving shaft at an instant which determines which of a number of groups of type are to be selected, and a printing clutch connects the carrier rocking means to the driving shaft at a subsequent point of the cycle thereby selecting a particular type from aparticular group. The type wheel 48, Figs. 1. 3, is freely journalled on arm 61 of carrier 61, 62 which is rotatable on shaft 47. Gear wheel 46 is also rotatable on shaft 47 and is in mesh with type wheel 48. Type wheel 48 is rocked towards the platen 85 by the action of complementary cams 63 driven by the printing clutch engaged at a pre-determined point of the cycle of operations by release arm 69. The driving shaft 40 driving gear 46 through the type setting clutch 41, 43 and gear 42 is driven from the gear 38, Figs. 3, 4, and shaft 67 driving the printing clutch 64, 68 is driven from gear 65 which is the same size and is mounted on the same shaft 37 as gear 38. Gear 38 is rotatably mounted on shaft 3 7 and is driven from gear 65 by the arm 96, Fig. 4, pivoted at 97 to gear 65 and having a slotted, end 103 slidable on block 102 pivoted to gear 38. Roller 98 pivoted to arm 96 engages cam 99 bolted at 100, Fig. 3, to the framework of the. mechanism so that during a cycle rotation of shaft 37'cyclical variations in speed of gear 38 and driving shaft 40 occur. Type selection is controlled by cards 10, Fig. 2 (not shown), which have one or more columns of 12 spaces. For each column there is a separate type wheel 48, gear 46, printing clutch 64, 68, and type setting clutch 41, 43. The type selected for printing depends on the particular spaces in a column in which a hole occurs. ' The typical characters are arranged on wheel 48 in groups of four each consisting of three letters preceding a numeral. A hole in one of the first nine spaces upwards' causes one of the groups to be selected and a hole in one of the remaining three spaces selects a particular letter of that group, of if there is no such letter hole the numeral of the group is printed. Insertion of the card in the card reading mechanism, Fig. 2 (not shown) commences the rotation of shaft 37 by means of a clutch magnet and pawl and ratchet mechanism. As the spaces of a card column, the lowest first, pass through the card reading mechanism, they pass brushes which complete a circuit to a solenoid 49, Fig. 1, when a hole in the column passes them. This causes movement of the corresponding call wire 51, the projection 52 of which engages the type selecting clutch 41, 43 through release arm 44, 54. Projection 45 of clutch 41, 43 engages with a particular notch of the ten notches on plate 41 depending on the position of the hole amongst the first ten spaces of the record card column since rotation of plate 41 has been taking place since insertion of the card. Each of these notches corresponds to one of the above type groups and thus the group corresponding to the record card hole, i.e., the selected group, will always be approaching the type position at a certain pre-determined point in the cycle. Shaft 37 makes one complete rotation during the complete passage of the card past the brushes and cams 60, 83 and 95 are mounted on shaft 37 to operate at cyclical points of this rotation. After nine spaces have passed the brushes, cam 95 operates bail 91 to return rod 51 to its original position and cam 60 causes bail 55, 56 to depress call wire 51 so that projection 52 can no longer coact with arm 54 but lower projection 53 is brought level with notch 80 on arm 70. Thus if there is also a hole in one of the remaining spaces on the card column, rod 51 will be moved to engage the printing clutch 64, 68 through bell crank 69, 70, and the type wheel 48 will be rocked and a particular letter of the three in the selected group printed. according to position of the second hole. When a numeral is to be printed there is no upper punched hole in the card column and call wire 51 is not operated a second time. Rod 70 is displaced at a later fixed point in the cycle by the action of cam 83 against arm 81 displacing arm 78a which had been raised into an operative position level with lug 80 on arm 70 earlier in the cycle by cam 71 and linkage 72, 76 when the type setting clutch was engaged. Since the distances between the last three holes on the card column are the same as those between the remainder, and the distance between adjacent letters in each group on the type wheel is a quarter of that between adjacent groups, it is necessary to reduce the speed of the driving shaft 40 to one quarter during selection of type characters from the selected group. This is arranged by the profile of the above-mentioned cam 99. The zeros of a multi-denominational number are inserted automatically by means of a latch 87 mounted on rod 76 which engages lug 88 on the rod 76 corresponding to the type wheel for the next lower order digit. By putting corresponding latches 87 out of action columns of figures can be split up into sections. The angular velocity of carrier 61, 62 at printing impression is arranged to be equal to that of gear wheel 46 so that the velocity of the type on type wheel 48 is zero with relation to the platen at the moment of impression.