Patent GB-787246-A (GB)
Title: Improvements in or relating to the electrical storage of information
IPC: H04Q3/42
Filed: 1954-03-24
Abstract: 787,246. Automatic exchange systems. ERICSSON TELEPHONES, Ltd., and TAUB, D. M. June 22. 1955 [March 24, 1954], No. 8553/54. Class 40 (4). The digits of a number are registered in turn in a multi-electrode gas discharge tube by causing a discharge therein to move directly from one electrode to an electrode particular to the digit to be registered, each digit so registered being then transferred in turn to a separate multi-electrode discharge tube in which it is stored before it is counted out. Use is made of dekatrons, such as are described in Specifications 712,215 and 712,171, [Group XL (a)], both for registering, storing, and counting out the digits. A keysender is shown schematically in Fig. 1 and in more detail in Figs. 2-10. The embodiment will be described with reference to both arrangements at the same time. Registration of digits.- In all the dekatrons the discharge is initially to the home electrode H. Operation of a digit key D0-D9, Fig. 2, corresponding to the first digit applies a negative pulse from the cold cathode tube V29, Fig. 8, to that cathode S1-S9 or H which is the tens complement of the digit in dekatron V4, Fig. 2, forming part of the pulse-in circuit PNC, Fig. 1. The discharge is therefore shifted directly to the selected cathode. This movement of the discharge applies a start condition through V6 and V5 to a multivibrator comprising tubes V1, V2 which applies pulses through double-triode V3a, V3b to guide electrodes Gdl, Gd2 so that the discharge is stepped back to the home electrode H, whereupon the multi-vibrator stops. At the same time the multivibrator applies pulses over leads 22, 23 to the gate circuits G1-G8. Gate G1 consists of rectifiers MR50, MR60, which are biased to conductive condition by tube V8 in the pulse-in distributer PND at this time. These pulses are therefore applied to the first dekatron counting tube V39 in the digit store DS1 to step the discharge along the tube. At the end of the impulse train when the discharge returns to home electrode H in tube V4 the increased potential on this electrode fires tube V7 to step the pulse-in distributer PND to V9 conducting with the other tubes V8 and V10-V15 extinguished, so closing gate Gland opening gate G2. The second and subsequent digits are registered in tubes V40, V41 and so on in like manner as decimal complements. Registration of digit O. Operation of digit key DO merely produces an end-of train pulse similar to that produced when tube V4 reaches home position. This pulse is produced by tube V31, Fig. 8, by way of leads 41 and 29 and applied by key DO to fire V7, Fig. 3, to step on the pulse-in distributer PND, the corresponding counting tube V39-V46 being unaffected. Transmission of digits. The pulse-out generator circuit PTG comprises a multivibrator V18, V19, Fig. 6, arranged to produce 10 impulses per second. The pulse-out distributer PTD has a cyclic ring of tubes V21-V28 controlling gates G9-G16, each of which comprises a pair of rectifiers such as MR20, MR30, Figs. 4, 5. Pulse-out control circuit PTC comprises two cold cathode bi-stable pairs V31, V32 and V33, V34, and a timing circuit V35, V36. The multivibrator V18, V19 is suppressed whenever V31 or V35 is conducting. Initially V31, V33 and V36 are conducting. When the first digit has been registered in tube V39 the end-of-train pulse fires V34 to extinguish V33 and prime V32. Operation of start key KS then fires V32, to extinguish V31, energize relay B, and fire V35 to produce an " inter-train " pause. During this pause V35 holds the grid of pentode V38 at earth potential to prevent operation of the multivibrator. At the end of the pause, determined by capacitor C77 and resistor R187, V36 re-fires to extinguish V35 and allow the multi-vibrator V18, V19 to operate. Pulses at the rate of 10 per second are thus applied through gate G9 to the dekatron V39 to drive the discharge on step-by-step to the home electrode. At this point a pulse from the home electrode appears on lead 44 to fire V47, Fig. 8, which refires V35 to stop the multivibrator, so producing an inter-train pause. A pulse from V47 also steps on the pulse-out distributer PTD. The other digits are sent in like manner. If the digit O is registered on any one of the tubes the discharge is stepped ten times to return to the home electrode. Transmission to line. Operation of multivibrator V18, V19 applies pulses to high-speed relay A at the rate of 10 i.p.s., relay A transmitting the pulses to the outgoing line OG over terminals X1, X2, Fig. 6. Restoration of apparatus to normal. A coincidence circuit CC consists of eight gates MR10-MR17, Fig. 4, controlled by tubes V8-V15, Fig. 3, of the pulse-in distributer PND. When all the digits of a number have been registered the tube, say V8, following the last digit is conducting so that the corresponding gate MR10 is open. As each digit is sent out the corresponding tubes V22-V28, Fig. 7, in the pulse-out distributer PTD fire without effect but when the last digit is sent and, in the example, V21 fires it passes a pulse through MR10 and over lead 35 to fire tubes V31, V33 to stop the multi-vibrator V18, V19 in the pulse-out generator PTG. A lamp V16, Fig. 2, lights when the first digit of a number is keyed and stays alight until the last digit is transmitted to line. The digit keys are ineffective during pulsing out. Errors. If digit keys are operated in error the registration may be cancelled by operation of reset key KR1/KR2 which first resets the control circuit, Fig. 8, and then the digit stores and distributers. Modifications. Sending may start immediately after the registration of the first digit. In this case the start key and tubes V33 and V34 are omitted and lead 38 is connected to the trigger electrode of V32. The start signal is provided by the first end-of-train pulse. Alternative arrangements must then be made for digit key DO. A visual indication of the number set up may be provided by tubes V39-V46.