Patent GB-754735-A (GB)
Title: Improvements in or relating to teleprinters
IPC: H04L17/24
Filed: 1954-03-01
Abstract: 754,735. Printing-telegraph receivers. AUTELCA AKT.-GES. March 1, 1954 [Feb. 28, 1953], No. 5996/54. Class 40 (3). [Also in Group XVI] In a teleprinter having the receiver mechanism and a printer mounted in a carriage movable along a platen, the printer comprises a type-head movable along and rotatable about an axis which is itself rockable in a plane perpendicular to the axis of the platen and in which the rocking movement of the type-head has three component movements-the first in which the type-head is brought within a short distance of the platen and during which it is rotated and moved axially to select the character for printing by co-operation with members set by the selecting mechanism of the receiverthe second component which causes the typehead to impact the platen for printing and the third component which returns the type-head to its initial position. Selecting mechanism.-The selector discs 11 mounted on a spindle 7 are rocked in accordance with the code elements of the received signal by levers 12 located in slots in the discs 11 and secured to shafts 18 connected to members 20 with knife edges 20a engaged by the pointed ends 10a of sword members 10 mounted on axes 17 carried by members 9 pivoted on pins 13 on a fixed plate 4 and rocked counterclockwise in succession by a cam 6a on a shaft 6. The sword members have extensions 10c, 10d associated with knife edges 32c, 32d of five elements of a member 32 rotatively set in accordance with the received signals-the engagement, for example, of the parts 10d, 32d rocking the sword member 10 so that, when it returns to its normal position it engages the knife edge 20a and rocks the connected lever 12 to position the associated disc 11. The member 32 is. positioned by the engagement of a forked extension 33 with a pin 28b on a lever 28 positioned by the engagement or non-engagement with a boss 26 on a rod 25 moved longitudinally by the operation of the armature 22c by the coil 22b or 22b<SP>1</SP> energized in accordance with the received signal element. A second lever 27 co-operates with the lever 28 to lock the rod 25 when it has been operated, the levers 27, 28 being moved outward simultaneously by a cam 30 on the shaft 5 to allow the free motion of the rod 25 in accord with the signal elements. Signal-receiving circuit.-The line receiving terminals 44 are connected to the winding 38 of a magnet 37 of which the second winding 39 is connected via an adjustable resistor 51 to the corners of a bridge 48 fed by a transformer 49 from A.C. mains 50. With current flowing over the line and armature 40 against contact 42, the winding 22b of the magnet 22 is energized. In response to a signal element constituted by an interruption of the line circuit, the armature 40 moves to contact 41 to complete a circuit for the winding 22b<SP>1</SP> of magnet 22 to move its armature 22c to the opposite position. Start-stop driving arrangements.-A gearwheel 141 connected to shaft 60 is connected by a friction clutch 143, 144 to a gear 140 driven from a motor 1 through a reduction gear train 137, 138, 139. The gear 141 meshes with a gear 146 mounted on the shaft 5 and formed with a hub portion carrying a stop-pin 148 having a top portion which can engage an adjustable abutment 150 and a lower portion engaging a pin 24 which is moved axially in response to the start impulse to allow the shafts 5 and 60 to be driven through one revolution. A cam on a subsidiary shaft released during each revolution of the shaft 5 rocks a toothed segment 57 to lift the selector levers 34 clear of the discs 11 during their setting in accord with the received signal elements. Type-wheel positioning mechanism and printer operation.-The shaft 81 of the type-wheel 80 is carried in a bracket connected to a shaft 63 driven from a shaft 64 connected by a dog clutch to an intermediate shaft connected to a shaft rotated with the cam-shaft 5. In the case of code combinations for case shift and functions, such as carriage return &c., the connecting action of the dog clutch is prevented so that the printing operation is suppressed. The first component of the movement is effected by a crank mechanism which is arranged so that in the dead-centre position the type head is almost in contact with the platen. The drive takes place through a clutch member 70 provided with internal springs so that a lever member 75 having a hook 75b engaged by a pin 77 on a crank 78 can, in the dead-centre position of the crank 72, provide the small additional movement to bring the type-head 80 against the platen 66. The rotational movement of the type-head is controlled by a bevel gear-wheel 83 on the spindle 81 engaging and moving with a rack 86 mounted on a plate 220 which carries two alternatively-operable, shaped stop arms 87, 88, Fig. 13, each having a slot such as 87b, which coacts with the selector lever 34 which has moved inwardly in the aligned slots of the discs 11, the purpose of the two arms 87, 88 being to increase the spacing of the selector levers with a predetermined travel of the type-head. When the rack 86 is arrested, the continued movement of the spindle 81 to the end of its rocking movement causes the gear-wheel 83 to effect the rotational movement of the type wheel to select the desired character. The type-head is locked at the end of the first component movement by a pawl 90 co-operating with a ratchet wheel 84 and released by a pivoted lever 92 operated by a cam 93a carried by an adjustable lever 93, the pawl 90 being freed from the ratchet when the type-head commences its return movement. An ejector segment 94 freely mounted on the shaft 63 is rocked by a lug 94a engaged by an abutment on the type-head carrier towards the end of the first movement and cams the selected lever 34 out of the slot in the feeler arms 87 or 88 so that the lever is freed from shock. The positioning of the appropriate ring 80a ... 80d of the -type-wheel in the printing position adjacent the platen is determined in the upper and lower case positions by the nature of the first selecting element of the code combination, characters whose first element is a space being, for example, allocated to rings 80a, 80c in the lower and upper cases respectively, whilst the characters in the rings 80b, 80d have a mark as the first selecting elements. In the letter-shift position, if the first code element is a mark, the selector lever 102 moves inwardly and allows a pivoted detent 99 to move inwardly to engage a projection 95b on a cam 95 which is retained so that a pin 98 on the frame 85 connected to the type carrier rides on the surface 95a of the cam to bring the second row 80b of characters on the type carrier 80. For an upper-case character the selector lever 103 moves inwardly and engages extension 108b of lever 108 which rotates in counter-clockwise direction and the retaining pin 107 releases the locking levers 100, 101. A lug 109a of a pawl 109 engages extension 108a to retain lever 108 in its adjusted position. The locking lever 100 engages with extension 96b to lock the cam disc 96, but the locking lever 101 is retained by the first-element selecting lever 102. If the first element of the character combination is a space, selecting lever 102 does not move inwardly, locking lever 101 is retained and the pin 98, riding on the cam surface 96a of the disc 96, lifts the type carrier 80 so that printing takes place from the ring 80c of characters. If, however, the first element is a mark, the selecting lever 102 moves inwardly so that the locking lever 101 moves inwardly and engages the projection 97b to lock the cam 97 so that the pin 98 riding on the surface 97a raises the type-head 80 to print from the ring 80d of characters. The cams 95, 96, 97 are returned to their normal positions by a pin engaging the end of slots 95c, 96c, 97c in the cam discs. A device, Fig. 19, for cushioning the return movement of the carriage comprises a cylinder 225 housing a piston 226 carried by a rod 230 of magnetic material. A closure member 228 has a bore 228a in communication with axial and radial holes in a tapered screw plug 229 A member 233 on the carriage is provided with a magnetic disc 234 by which the piston is moved to the right during the spacing movements of the carriage.