Patent GB-618225-A (GB)
Title: Improvements in or relating to code controlled electrical telegraph or control systems and apparatus
IPC: H04L15/26
Filed: 1944-01-17
Abstract: 618,225. Electric selective signalling. WINTER, A. C. Jan. 17, 1944, No. 884. [Class 40 (i)] [Also in Group XL (b)] In an electric signalling system using a code with spacing elements of predetermined length between signal elements of unequal length, e.g. the Morse code, the controlled apparatus comprises means for comparing the received signal elements, e.g. dots and dashes, with the code spaces between the signal elements. The apparatus may be arranged so that a circuit is selectively built up to close a desired contact member in response to a predetermined sequence of signals, or an alarm, such as a bell or a lamp, may be operated by a circuit completed by the sequential reception of signals corresponding to the letters SOS. The invention is described in its application to the control of a printing telegraph receiver. The current impulses corresponding to dots and dashes operate a solenoid 16, Fig. 2, which through a pivoted shoe 20b clutches a constantly rotating recessed disc 47 to a character cam 10 provided with a projection 48a. Similarly, the solenoid 19 energized during the space periods connects the spacing cam 11 to the constantly rotating sprocket 23a, the cam 11 being rotated at twice the rate of the cam 10. A number of these units 10, 11 is provided corresponding to the maximum number of signal elements (dots and/or dashes) in a letter or character. The cams 10 are provided with limited arcuate recesses 67, 68 (Figs. 15, 16, 17) and the cams 11 have a switch-box assembly comprising pins 61, 62 selectively closing an electric circuit according to the movements of the two cams 10, 11 in response to a dot or dash. As shown, the cam 10 is rotated through an arc of X or 3X in response to a dot or a dash respectively, the spacing cam 11 being rotated through an arc of 2X in response to the space between signal elements. Friction pads 53 are held against the discs 10, 11 during the reception of a signal combination to prevent over-running movement. After the printing operation has been effected; arms 55, 55 are operated to release the friction pads and allow the cams 10, 11 to return' to normal position, with projections 10b, 11b arrested by a stop 69, under the action of cords 57 and springs 58. A projection 11b on the spacing cam 11 engages switch members 74, 75, the first of which controls the letter cam of the group WL comprising a letter cam 80 and word cam 81 and the second member controlling the circuit of the space cam solenoid 19. The switching assembly 74, 75 is carried by a manually adjustable regulator R whose position determines the timing of operation of the auxiliary functions, such as printing, letter or word spacing. The word cam 80 and letter cam 81 are controlled by solenoids 83, 84 operating clutch members which connect constantly rotating hubs 82 to the cams by pins 86a, 87a. The cam 80 during its rotation engages a switch member 94 controlling word spacing and a tooth 81b on cam 81 engages in succession switches 95, 96, 97 which control respectively the word cam, the printing cam and the solenoid controlling the rotation of the letter cam. The dots and dashes are selectively applied to electromagnets controlling pivoted code bars 1X, 1Y, 2X, 2Y, &c., and for character selection an assembly of notched code bars 108 is moved downwardly by printing magnet 117, the selected type bar continuing to move downwardly after the others have been arrested and its pin 123 striking the corresponding key 124 of a typewriter T. For word spacing the solenoid 125 is operated and at switch 128 opens its own circuit and that of relay MR releasing solenoid 83 of the word cam. In the circuit arrangement, Fig. 11, the receiving relay 135 controls a solenoid 136f operating a two-position switch arm 136a engaging . contacts 136c, 136d associated with the solenoids 19, 16 respectively. When a signal impulse is received, solenoids 136f, 137f and 138f all operate, contact discs 138d and 138dd being moved forward to position 1 and current for a dot or a dash passes to solenoid 16 of the first cam assembly 1C, 1S. When a space begins disc 137d is moved one step and over contact 136c solenoid 19 is operated. The space cam 11 rotates and when it closes switch 74, the solenoid 84 controlling the letter cam 81 is operated. If no further signals are received for that letter group, letter cam 81 closes switch 95, operating solenoid 83 and word cam 80 which actuates switch 96 to energize the printing magnet 117 and opens switch 97 in its own circuit. A magnetic relay MR is energized and holds the circuit of solenoid 83 closed, even if switch 95 is opened, until the spacing interval ends and a further signal is received. If no signal is received, word cam 80 closes switch 94, energizes spacing bar solenoid 125 which opens switch 128, thereby breaking the circuit of relay MR and releasing solenoid 83 controlling the word cam 80. The movement of the arms 55 to effect release of the friction brakes 53 is effected by a toothed carriage 182, Fig. 8 and Fig. 12 (not shown), engaging a ratchet-wheel 180 on the shafts 56, the carriage being moved downwardly against a spring 185 by a solenoid 184, Figs. 8, 11. In the circuit arrangement of Fig. 11, solenoid 150a releases simultaneously with printing solenoid 117 and moves contact disc 150f one step. Over the contact (marked shaded) and closed contacts 161, 162, solenoid 184 is energized, operating the toothed carriage 182 to release the friction brake and at the same time urging a short shaft carrying a cam 165 into frictional engagement with a shaft 174 continually rotated from the main shaft 40. The cam 165 is moved through approximately 180 degrees opening contacts 161, 162 and releasing solenoid 184 so that the carriage is raised by spring and the arms restore the friction brakes to the cams 10, 11. The cam closes contacts 160, 162 so that on the completion of the following printing operation the disc is moved one step and the solenoid 184 again operated to release the friction pads 53 from contact with the cams 10, 11. The receiving arrangement may be provided with more than four sets of character and spacing cams, 1CS, 2CS, 3CS, 4CS-and may be modified to ring a bell on receipt of an " SOS " signal by utilizing nine sets of cams and transmission of the signal without spacing between the letters S, O, S. In the automatically regulated system the rate of operation of the receiving apparatus is controlled in accordance with the space between the first and second signal impulse of the preceding letter group. A speed regulator member 200, Fig. 26, corresponding to the manually-operated member 70 of Fig. 2 is rotated during each letter group to a position determined by one of two swinging arms 230, 231, the position of which has been determined by switch arms 255, 256 during the first space interval of the proceeding signal group. At the beginning of the first space of a signal group, the receiving relay closes contact 136c operating the first spacing-cam solenoid 1S and solenoids 217, 273, 274 in parallel through one of the closed switches 295, 296 and contact disc 300-2 and of alternator 300. The solenoid 217 connects the regulator 200 to a continuously rotating shaft 204 through clutch mechanism, Fig. 24 (not shown), and solenoids 273, 274 connect the switch arms 255, 256 through similar clutch members, the arms rotating more slowly than the member R and approximately at the same speed as the spacing cam. The regulator is stopped when the appropriate switch 295 or 296 is opened by the corresponding member 230, 231 set during the previous letter group. The switch arms 255, 256 rotate until relay 136 operates for the commencement of the next signal and circuit of relays 273, 274 is broken. Solenoid 301 is operated in parallel with solenoid 2C and the appropriate solenoid 246, 248 appertaining to the arm 230, 231 in rest position is operatedas shown, the solenoid 248 over a circuit including the shaded contacts of disc 300-1 of the alternator. The appropriate swinging arm 321, in this case, rotates until the circuit of its clutch solenoid 248 is opened at switch 258 at the position determined by the switch arm 256. At the end of the second signal element of the letter, solenoid 301 releases and steps the discs to the alternate set of contacts associated with the other swinging arm. The regulator 200 and swinging arms are released to return to normal positions by operation of solenoids 224, 275. and 276 in parallel with release relay 184. At the same time the swinging arm 230, the setting of which has been utilized, is released by operation of a clutch solenoid 247 through the unshaded contact of alternator disc 300-3. In the case of letters E and T having a single signal element, a dot and dash respectively, the regulator remains as set by a preceding signal group until a signal group providing a space between the first and second signal elements is received. Specifications 618,234 and 618,235, [both in Group XL (b)], are referred to.