Patent GB-807035-A (GB)
Title: Improvements in or relating to printing mechanisms
Inventor: WRIGHT THOMAS OLIVER
IPC: B41J7/54
Filed: 1956-09-07
Abstract: 807,035. Typewriters &c. BRITISH TABULATING MACHINE CO. Ltd. July 26, 1957 [Sept. 1956], No. 27441/56. Class 100(4) Type wheels; type-wheel selection. A cyclically operable printing mechanism has a typewheel with a plurality of sequentially arranged groups of type characters so that more than one character may be printed during each revolution of the type-wheel selecting means operable in each cycle to position any one of the characters in only one of the groups for printing under control of a timed character representing pulse or pulses, the selecting means being effective for different ones of the groups in successive printing cycles. Typewheels 27 each bear four groups of type representing the numbers "0" to "9", and may be controlled by electrical impulses from punched cards. Such as impulse energizes one of start magnets 1 and armature 3 is drawn clockwise about pivot 122 to turn arm 5 anticlockwise about 6 so that end 7 will be moved from notch 8 to notch 9 of detent 10. Projection 15 on arm 5 is withdrawn from tooth 16 on plate 17 when magnet 1 is energized, thus allowing plate 17 to energize and turn with plate 18, gear 19 and shaft 20 which is continuously driven anticlockwise. Typewheel 27 is driven by shaft 20 through gears 19, 21, 23, 25. The clutch is disengaged by cam 41 on shaft 40 which lifts arm 30. Lug 33 of arm 30 lifts arm 5 so that projection 15 reengages teeth 16. During disengagement of the clutch, arm 35 holds the typewheel stationary by engaging notches 34 in plate 18. During typewheel resetting the clutch is disengaged by arm 43 co-operating with cam plate 22 to move arm 30. Cam plate 22 rotates clockwise and end 95 of arm 43 rides up projection 45, thus projection 47 of arm 43 pivots bell-crank lever 49 about 50 and end 51 lifts arm 30. The typewheels are reset with "0" in printing position. The particular point in the printing cycle at which the start magnet is energized determines the character printed. After printing has occurred a reset impulse is transmitted to the start magnet and the clutch is again engaged. As typewheel 27 approaches the next reset position arm 43 is moved by one of the projections 45 to cause arm 30 to disengage the clutch. Cam shaft 52 controls printing. Nose 54 of plate 29 drops into notch 53 allowing plate 29 to rock and move typewheel 27 towards platen 62 urged by adjustable spring 55. Adjustable impression arrangements. Force of impression may be adjusted by moving plates 65 on side-frames 28. Zero suppression. Lug 78 of locking lever 71 lies in hole 79 of typewheel mounting plate 29 and prevents the plate rocking to print when "0's" are not required to the left of significant figures. When a type other than "0" is selected plate 77 rotates with gear 25 and nose 75 is lifted out of notch 76 so that lug 78 moves upwards and clears shoulder 80 thus alowing plate 29 to be rocked. To allow "0" to be printed electromagnet 81 is energized and lug 78 is raised through armature 82, wire 83, and bell-crank lever 84 which is maintained in operated position by projection 87 of latch arm 88 which engages notch 92. Pin 94 in plate 29 engages end 93 of arm 88 and lifts projection 87 out of notch 92 as plate 29 rocks to print and allows bell-crank 84 to restore to normal position. The circuit for energizing magnets 1 and 81 for the selection of type to be printed is dependent on interlock contacts 105, 106, 107 operated by the lower end of lever 43 through members 101, 104. Arrangement of type characters. More or less than four groups of type may be used and a different number of types in a group may be provided. Also the groups may contain different characters or the same characters in different founts. In the latter two cases provision must be made for keeping the type wheel synchronized so that all print the same characters or founts, e.g. by making notch 44 deeper and providing an extra set of contacts like 106 in such a relation to arm 43 that one pair is made when arm 43 drops into the deep notch and the other pair is made for the rest of the cycle to provide a reset circuit and suppression of printing until all wheels are synchronized. Alternatively all type wheels may be reset regardless of whether or not thev have been selected. Specifications 605,132 and 704,764 are referred to.