Patent GB-377241-A (GB)
Title: Improvements in or relating to power operated typewriters
IPC: B41J23/06
Filed: 1931-01-24
Abstract: 377,241. Typewriters. BURROUGHS ADDING MACHINE CO., 2nd Avenue, Detroit, Michigan, U.S.A.-(Assignees of Pasinski, W. J. ; 1988, East Grand Boulevard, Detroit, Michigan, U.S.A.) Jan. 24, 1931, No. 2433. Convention date, Jan. 25, 1930. [Class 100 (iv).] Relay type-lever actions.-In actions comprising means for coupling the type-levers to the driving-means, such coupling-means being normally urged into operative position but being restrained by key-controlled means, the restraining-means returns into position for restraining the coupling-means before return of the latter. Provision is made for effecting repeat impressions by abnormal depression of the keys. To obtain uniform impression of upper and lower case characters, means is provided for increasing the speed of the typelevers when upper-case characters are typed. A yieldingly suspended cushion for preventing rebound of the type-levers may be provided. In the machine shown in Figs. 2 and 6, each type-lever 80 is connected by a link 79 to a rocking arm 73 carrying a pawl 71 co-operating with a ratchet-wheel 70 on a shaft 28. The pawl is normally held in disengaged position by a detent 84 co-operating with a shoulder 92 on a dog 89 carried by a key-lever 61. The detent and dog are held against pins 87, 90 by a spring 83 which is connected to the pawl, and a finger 94 pivoted on the rocking arm, an ear 94a on the finger normally abutting on the pin 90. On short depression of the key-lever, the dog rocks the detent, the pawl snaps into the ratchet-wheel, the type-lever is swung into proximity to the platen, the pawl is disengaged by the means described below, and the stroke of the type-lever is completed by momentum. For disengaging the pawl, the finger 94 is formed with an extension 96 which co-operates with a slotted plate 64 to rock the finger and thereby cause the pawl to snap out of engagement with the ratchet-wheel, the movement being initiated by the ear 94a and completed by the spring 83 when the latter has been carried above the pivot 72 of the pawl. During depression of the key-lever, the dog is displaced by the pin 90, and the detent is permitted to return to normal position. On release of the key-lever, a spring 82 returns the arm 73, and the pawl again engages the detent. To provide for repeat impressions, the detents 84 are arranged in the path of rods 107, Fig. 6, connected to a bail 106 in the path of lugs 103 on key-stems 60 which have lost-motion engagement with the key-levers and are held up by springs 102. On normal depression of a keystem it moves bodily with the key-lever, and the type-lever is operated once only, but on abnormal depression the lug 103 rocks the bail 106 and disables the associated detent, the type-lever being operated repeatedly so long as the key-stem is held depressed. The shaft 28 is geared to a shaft 24 provided with a wormwheel 23 engaging a worm on the shaft 21 of a motor 20. To prevent damage if the machine jams, the worm-wheel is yieldingly connected to its shaft by a coupling consisting of spring- pressed balls. The speed of the motor is regulated by means of a bell-crank 44, Fig. 6, which is pivoted on a bracket 47 and carries a contact co-operating with a'stationary contact. The bell-crank is connected to an adjustable spring 50 and abuts on a plunger which is mounted in a collar 40 on the shaft 21 and abuts on centrifugal members 41 pivoted on the collar. To provide for uniform impression of upper and lower case characters, the carriageshift frame 130 is connected by a link 170 and spring 171 to a rod 172 having a head 174 for engaging the bell-crank 44. When the shift frame is raised, the head engages the bell-crank, and the force opposing the members 41 is increased, the motor being thereby speeded to increase the speed of the type-levers. The spring 171 may be connected to an arm 178 which is pivoted on the link 170 and engages an adjusting-screw 176. A rebound-preventing pad 180, Fig. 2, for the type-levers is suspended in a guide 184 by means of springs 182. The pad may be formed from insulated cable, the wires having loops for attachment to the springs. Keyboards.-For enabling the keys 60, Fig. 2, of the machine to be fingered in the ordinary manner in spite of their short stroke, the slope of the banks is made less than that of the standard keyboard, and the keys when depressed have the same positions as those of the standard keyboard. Key interlocks.-To prevent depression of more than one key, the key-levers 61, Fig. 2, have tapered projections 68 co-operating with rollers 69 in a channel 69a. Carriage-shift mechanism ; shift-key actions. -A cable wound on a power-operated drum and connected to the shift frame is tightened by the shift key and is thereby caused to raise the shift frame. , In the arrangement shown in Fig. 6, the carriage-shift frame 130 is connected to a link 140 having lost-motion connection with a lever 147 abutting on a lug 145 on the shiftkey lever 144. A cable 141, wound on a drum 142 on the shaft 28, is connected to the link 140 and an adjustable arm 151 on the lever 147. On slight depression of the shift key, the cable is tightened and the carriage is shifted. If the shift key is held, the cable slips and the carriage remains shifted. If the cable fails to act, further depression of the shift key effects shift manually. A raw-hide cable and a drum of self-lubricating fibre are preferably employed. Letter-spacing mechanism ; space-key actions. -The action-arms 73, Fig. 2, operate a universal bail 120 having a pin 116 engaging a cam 115 on a rocking arm 113 connected to the escapement rocker 110. The space bar 123 has an arm 126 engaging a pin 127 on the arm 113.