Patent GB-190728736-A (GB)
Title: Telegraph Typewriter.
Inventor: CARDWELL GEORGE ALEXANDER
Filed: 1907-12-31
Granted: 1908-12-17
Abstract: 28,736. Cardwell, G. A. Dec. 31. Tedegraphs.-The rotation of the type-wheel of a page-printing telegraph is effected in three steps by three current impulses, which are transmitted over one or more lines, and close in the desired order, by means of a system of four selective relays, certain of four local circuits, which control the motions of the type-wheel. The four relays may be included in one main-line circuit, in which case transmission is effected by long and short impulses of both polarities ; r two differently polarized relays may be included in both of two main line circuits, in which case impulses of both polarities sent over both lines affect the transmission ; or four main lines may be used. The first impulse transmitted allows the spring-actuated type-wheel to rotate a certain number of quadrants till arrested by a stop, the extent of this rotation depending on the local circuit which has been closed. The first impulse also causes the closure of certain contacts. so that on the arrival of the second impulse, a second stop is raised, and the type-wheel is allowed to rotate a certain number of approximate twelfths of a revolution. The third impulse allows in a similar manner the final movement of the type - wheel though a certain number of approximate thirty-sixths of a revolution. The type-wheel is then in position, and on the cessation of the third impulse, printing takes place due to the de-energization of a magnet, the armature of which, on falling back, completes a circuit through the printing -magnet. After printing, the typewheel completes the revolution and is ready for actuation by a second series of impulses. The other operations of letter-spacing &c. are similar to those in an ordinary typewriter, but are all controlled from the transmitting station. After each printing stroke, the carriage that supports the paper sheet or roll is advanced a space against the force of a spring, through a ratchet-and-pawl arrangement, actuated by an electro - magnet in circuit with the printing-magnet. The carriage return at the end of a line is effected by the electro-magnetic release of the coiled spring, by a given series of three impulses. Line spacing is also effected through a ratchet-and-pawl device by a series of threeimpuises, and the lifting of the typewheel, which has two rows of characters, to bring the lower row of characters opposite the printing- hammer, is also brought about by a similar series. On the shaft of the type-wheel 7, Fig. 2, are attached four arms 26, 27, 28, 29, Fig. 6, in the path of the longest 26 of which are arranged a circle of stops 34, 38, &c. Three sets of three stops 50<a>, 50<b>, &c. are arranged in the first quadrant of the circle in the path of all the four arms. Normally the long arm 26 rests against the zerostop 30, but on the arrival of the first impulse, one of the local circuits 1<1>, 2', 3', 4<1>, Fig. 1, is closed by one of the selecting relays 5, 5<1>, 6, 6<1>, causing the elevation, by its actuating electro-magnet, of one of the quarter-stops 34, 35, 36, 37, and the withdrawal of the zero-stop 30, whereupon the type-wheel rotates under the influence of its motor -wound spiral spring until the arm 26 is arrested by the raised stop. The energized stop-raising magnet, which is maintained energized by a holding circuit, closes contacts which place three actuating electro-magnets of the division stops 38, 39, 40 or 41, 42, 43, &c., of which three are arranged in each quadrant, in circuit with the main local circuits 1<1>, 2<1>, 3', 4<1>, Fig. 1, so that on the arrival of the second impulse, one of these division stops is raised, and the first raised stop being withdrawn due to breaking of the holding circuit, the long arm 26 rotates until arrested by the raised division stop. In a similar manner, the armature of the electro-magnet of the raised stop places the three electro-magnets of one of the three sets of subdivision stops 50<a>, 50<b>, 50<e>, &c. in the first quadrant in communication with the main local circuit wires 1<1>, 2<1>, 3<1>, 4<1>, so that on the arrival of the third impulse, one of these subdivision stops is raised, and, as before, the second raised stop falls and the type-wheel rotates till one of the short arms 27, 28, 29 comes in contact with the raised stop. At the cessation of the third impulse, a magnet is de-energized, and its armature in falling back closes the circuit of the electro - magnet that actuates the printing- hammer 18, Fig. 2. The circuit through the printing-magnet having been completed, the holding circuit is broken by a relay in the printing circuit, so that the printing - magnet circuit is broken at another point, the stop-actuating electromagnets are de-energized, and the type-wheel completes the revolution, coming to rest with the arm 26 against the zero-stop 30. The advance of the paper-carrying carriage 16, Fig. 2, after each letter is printed, is effected through a ratchet-and-pawl device, which is operated by an electro-magnet in series with the printing-magnet, and causes the rotation of the spur-wheel 78<1> gearing with a rack 78 carried on the carriage 16. When the end of a line has been reached, a series of three impulses is sent, which, by actuating a particular magnet, causes the crown gear 81 to be withdrawn from its engagement with the crown gear 80, which is attached to the spur-wheel 78<1>, so that the spurwheel then rotates under the influence of a spring, wound by the advance of the carriage, and carries back the carriage 16 to its starting position.