Patent GB-496630-A (GB)
Title: Improvements in or relating to spacing-mechanism for typewriting machines
IPC: B41J19/32
Filed: 1938-04-04
Abstract: 496,630. Typewriters. INTERNATIONAL BUSINESS MACHINES CORPORATION. April 4, 1938, No. 10254. Convention date, April 8, 1937. [Class 100 (iv)] Letter-spacing mechanism.-The typing-keys control mechanism for effecting a spacing- movement depending on the width of the typed character and that of a previously-typed character. In the mechanism shown in Figs. 2 and 3, typing-key levers 15 control engagement of cam-devices with a driving-roller the wide, intermediate, and narrow characters such as W, A, I on the type-levers being six, four, and two units in width respectively. The key-levers 15 have lugs 15b co-operating with one of three bails 18, 19, 20 in connection with levers 21, 22, 23 which control engagement of other cam-devices with the driving- roller. These cam-devices are connected to bails 25, 26, 27 which are connected by links 30 to bell-cranks 31, 32, 33 having lugs 31a, 32a, 33a engaging a rocking arm 37 connected by a link 56 to a rocking plate 57. A pawl 73 on the rocking plate 57 co-operates with a ratchet-wheel 64 on a shaft 55 geared to a rack 63 on the carriage. The lugs 32a, 33a engage also rocking arms 43, 44 which are connected by links 45, 46 to cams 47, 48 respectively. The cams engage rollers 51 on a sliding link 52 in connection with a rocking plate 54 having a stop 75 for the pawl 73. The rocking plate 57 carries a dog 84 having a lug 84a for co-operation with notches 83a, 83b 83c in a slide 83 which is guided by a strap 86 and is connected to a lever 79 having a lug 79b which is engaged by a roller 82 on the rocking plate 57 when wide and intermediate characters are typed. A detent 89 co-operates with notches 83d, 83e in the side 83. When any typing-key is depressed, the rocking arm 37 is operated by a cam-device, the rocking plate 57 is displaced, and the pawl 73 co-operates with the ratchet-wheel 64 to effect letter-spacing, the spacing-movement being determined by the position of the stoppin 75 and the initial position of the rocking plate. If the rocking plate is initially in the position shown in Fig. 3, and neither of the cams 47, 48 is displaced, the pin 75 arrests the pawl 73 after a spacing-movement of six units, whereas if the cam 48 or 47 is displaced arrest occurs after a spacing-movement of five or four units respectively. The initial position of the rocking plate is dependent on the previous spacing-movement, since when wide and intermediate characters are typed, the lever 79 and slide 83 are displaced and retained momentarily by the detent 89, and the pawl 84 co-operates with the notch 83a or 83b to arrest the rocking plate 57 after a return movement of six or five units. When narrow characters are typed, the lever 79 remains at rest, and the pawl 84 co-operates with the notch 83c to arrest the rocking plate after a return movement of four units. After the typing of a wide character such as W, the parts remain in the position shown in Fig. 3, and if the narrow character such as I is typed, the cam 47 limits the spacing-movement to four units, that is half the width of the character W plus half the width of the character I. If an intermediate character such as A follows the character W, the cam 48 limits the spacing-movement to five units. If a wide character follows a wide character neither cam is set, and a spacing-movement of six units occurs. The cam-devices in connection with the key-levers are so arranged that spacing occurs before the type-levers commence to move. The space-bar 42 controls a cam-device operating, through a link 39 and a bell-crank 38, a bell-crank 59 carrying a pawl 70 which co-operates with the ratchet - wheel 64 to effect a four - units word - spacing movement. The members 54, 57, 59 are separated by thrust-bearings comprising discs having holes which receive balls.