Patent GB-264553-A (GB)
Title: Electric telegraphs
IPC: G08C21/00
Filed: 1925-09-16
Abstract: 264,553. Pein, H. Sept. 16, 1925. Writing telegraphs. - Consists in a method of and apparatus for producing written characters telegraphically. According to the invention, each character in a predetermined form of handwriting is resolved into two component curves which constitute the basis upon which control members, adapted for selective operation, are formed; these members control electrical energy which, when transmitted to a receiving apparatus, actuates a recording, device in such a manner that -.the component curves are recombined to form the written character. 'The control members .may consist of cams, shaped in accordance with the component curves; or they may consist of suitably graded electrical resistances. In another method of carrying out the invention, the transmission of energy is effected photo-electrically, the control members in this case consisting of light-transmitting bands of varying transparency, the variations corresponding in each instance to the form of an individual component curve. Fig. 1 shows diagrammatically a way in which a written character, such as the letter " e," may be resolved into component curves y, y<1>. The curve y<1> is, when necessary, modified by reducing the ordinates of all points on it by amounts corresponding to the travel of the paper on which the recorder writes in the receiving apparatus. A succession of such modified curves is shown at z, Fig. 3. A machine embodying the invention, shown in Fig. 7, comprises cam discs 5 mounted on a motor-driven shaft 6, each disc having on its edge two distinct portions corresponding in form to the component curves of a given character. Arranged at opposite sides of each disc 5 are rollers 10, 10<1>, carried by flexible supports 12, 12<1> on a cross-bar 13. These rollers are movable vertically, and normally lie out of contact with the cam discs, as shown in dotted lines. A keyboard is provided, each key lever 16 being connected to the support for a particular pair of rollers. When a selected key is depressed, the corresponding rollers 10, 10<1> are raised and held interposed between the disc 5 associated therewith and " universal " rollers 24, 24<1> extending. along the whole length of the cam shaft. These rollers, which are suspended on pivoted arms 25, 25<1>, are oscillated by the cam disc 5, acting through the rollers 10, 10<1>, the oscillations. of the roller 24, produced by one cam-portion of the disc, being transformed into current fluctuations in a circuit 1 by means of a resistance 66 varied by an arm 65 moving with the roller; similarly,. fluctuations corresponding to the other cam.portion of the disc 5 are set up in a circuit 2. The two circuits include respectively electromagnets 67, 67<1> in the receiving instrument, the armatures of which actuate rods 3, 3<1>, which by their combined movements guide a writing member 4 so as to reproduce the character represented by the cam disc 5 in action at the time. In addition to this electricallyoperated writing-device at the receiving end, a mechanical writing-device is provided at the transmitting instrument, and comprises a pen 4a guided by member 29, 31 which are actuated by levers 27, 27<1>. Means are provided in the transmitting machine for limiting the movement of the cam shaft to one revolution on each depression of a key, the transfer rollers 10, 10<1> being automatically restored to their inoperative position when a half-revolution has been made. The recording tape is fed forward by mechanism geared to the shaft 6. The cam discs may be arranged in pairs representing capital and small letters. Instead of a keyboard, a perforated band may be used for operating the control-members. Various modifications of the above-described machine are shown. In one construction, the written characters are recorded by a plurality of pens in the transmitting-instrument so that a multiple record of the transmitted message is made. A modification in the mechanism for guiding the writing-members and the formation of the control-cams upon the edge of a worm are also described. Instead of producing current fluctuations in the lines by using variable resistances such as 66, Fig. 7, the fluctuations may be produced inductively. Further, where resistances are used, these may be constructed as rings 71, 71<1>, Fig. 15, of material such as scheelite, the rings forming an edging of varying depth around conducting discs 5a, 5<a1>. These discs are mounted on shafts 6<a>, 6<a1>, and each pair of discs corresponds to one of the cams 5 in the machine shown in Fig. 7. Details of a machine embodying the features shown in Fig. 15 are described and illustrated. Fig. 16 shows the application of the invention to photo-electric apparatus. Light from a source 88 passes through a slit 91 and falls on a perforated band 93, each perforation corresponding to a component curve of a particular character. A ray passing through a given perforation falls on the corresponding unit of a series of strips 97, 97<1> - - provided on a rotating cylinder 96 of glass or the like, each strip being graded in transparency in accordance with a component curve of a particular character to be transmitted. The modulated light ray is reflected by a. mirror 96<1> on to a photo-electric cell 87 which is in a circuit including the receiving apparatus. By this means the necessary current-fluctuations are transmitted to the receiver. A maltese-cross device actuated by the rotating cylinder 96 effects the appropriate stepby-step movements of the band 93. The above description explains the principle of the apparatus, shown diagrammatically in Fig. 17, used for transmitting simultaneously the two component curves required to produce a written character. The light from the source 88 is intercepted by a band 93a provided with two corresponding rows of perforations, the two rays which pass simultaneously through any pair of associated perforations traversing separate " light-filtering " bands on a cylinder, and then being reflected by mirrors 97a, 97<a1> on to cells 87a, 87<a1> respectively included in the separate circuits leading to the receiving instrument. Means are described whereby various kinds of " light-filtering " bands may be produced for the purpose specified. In addition to having the requisite gradations of transparency, the bands may be so formed (e.g. by having equally spaced opaque lines of even thickness marked thereon) as to set up current pulsations of definite frequency. With this modification, the photo-electric apparatus may be used for effecting the transmission of written characters by wireless. Figs. 21 and 22 show diagrammatically a system for this purpose. Two low-frequency oscillations of different periodicities, say 500 and 700 per second, are superposed on a carrier wave sent out from a transmitting aerial 135, each low-frequency wave being set up by using a light-filtering band formed as described above, and each being modulated at any given time in correspondence with a component curve of the character being transmitted. In the receiving apparatus 136 the carrier wave is rectified and the two low-frequency waves are separated out by tuned circuits, each of which controls its own electromagnetic device 67 or 67<1> whereby the component curves of the written character are combined so that the writing- member 4 is appropriately moved. Specification 7678/00 is referred to.