US2306882A - Selective system - Google Patents

Description

Dec. 29, 1942. w. H. T. HOLDEN 2,306,382

SELECTIVE SYSTEM Filed March 11, 1941 3 Sheets-Sheet l INVENTOR y W H. 7THOL DEN A TTORNEV Dec. 29 1942. w. H. T. HOLDEN SELECTIVE SYSTEM Filed March 11, 1941 3 Sheets-Sheet 2 A TTORNEV FIG. 3.

Filed March 11, 1941 3 Sheets-Sheet 3 a. I *1 I Q 55, WM/H INVENTOR WHTHOLDEN I A rom/5 Patented Dec. 29, 1942 SELECTIVE SYSTEM William H. T. Holden, Woodside, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application March 11, 1941, Serial No.. 382,731.

5 Claims.

This invention relates to the selection and identification of lines, trunks, circuits or other electrical devices.

An object of the invention is to enable the selection and identification of lines or other circuits from a group with a minimum of interference and error.

Another object is to accomplish this purpose at increased speeds and with a minimum amount of connecting and controlling equipment.

It is often necessary in switching systems, particularly in telephone systems, to identify desired lines or other circuits in a group and to set up registrations or indications in accordance with the digital characters of their designations. If two or more lines require selection and identification at the same time, diificulty is likely to arise where the lines are arranged in coordinate groups and coacting mechanisms are used for selecting the lines. For instance, a group of one hundred lines may be divided into ten groups of ten each, appearing in coordinate rows in a switching mechanism for selection and identification by their tens and units digits. A single line is readily selectable by determining its tens and units rows. However, if attempt is made to select two lines simultaneously, double connections are likely to occur since all tens rows are in coordinate relation with all units rows. To

obviate these false operations complicated and expensive mechanisms have been required in the past.

According to the present invention the foregoing objects are realized and advantages are obtained over selecting systems used in the past by means of a selecting and identifying system in which two groups of discharge devices or tubes serve to select and to identify accurately any line in a plurality of groups which may contain a pluralit of lines calling simultaneously for attention. More specifically, the successive discharge tubes of the first group correspond to the tens digital designations of successive groups of lines; and the tubes of the second group correspond to the successive units designations of the lines in each one of the tens groups. The lines of each group appear in the electrodes of the corresponding tens tube and in the electrodes of the ten corresponding units tubes, and no connecting medium is required for associating the lines of one group with the tubes to the exclusion of other groups. Both the tens and units tubes are rendered operative by the calling condition on the lines and by the application during the existence of this condition of phase impulses, the

impulses of the successive phases being applied respectively to the successive tens and units tubes in the groups. When, therefore, a calling condition occurs on one or more lines. in one or more groups, a tens tube corresponding to one of the calling groups discharges in response to the application of the phase impulse and instantly disables the remaining tenstubes to:- prevent av second one from discharging. The discharge of the operated tens tube conditions. for operation all units. tubes corresponding to calling lines in the. chosen tens group. As soon thereafter as a phase impulse is applied to a units tube in which a calling. line appears, the tube discharges and in.- stantly: disables the. remaining units tube. Thus only one tens tube and only one units tube rep-- resenting the digital. characters of one calling line may be discharged, although other lines are calling simultaneously. The discharged tubes cause the. operation of associated relays to reg;- ister the designation or otherwise to indicate the identiy of the calling line.

A. feature of the invention is a tube control system in which the operating potentials applied to the. electrodes of the units tubes are the result of potentials produced by a discharged tens tube and the potentials appearing on calling lines. With this arrangement it is impossible for any one of the units tubes to discharge until a tens tube representing one or more calling lines has operated and rendered ineffective the remaining tens tubes. Thus the identification ultimately obtained will always be the true designation of some particular calling line and will not include one digit of one line and another digit of another line.

These and other features of the invention will be discussed more fully in the following detailed specification.

In the drawings accompanying the specification:

Fig. 1 illustrates a plurality of subgroups of lines from which selection is made;

Fig. 2- (-placedbelow Fig. 1) shows two series of selecting tubes, one series pertaining to the line groups and theother series pertaining; to the lines of each group. This figure also illustrates an impulse producing mechanism: for: operating" the tubes and anindicating or registering mechanism for receiving the registration of the. selected lines; and

Fig. 3 shows an alternative form of the circuits for operating the selecting tubes.

The selecting system disclosed herein, which e comprises series of space discharge tubes correspending to the designation characters of lines, links, trunks, or other circuits, may be used for a wide variety of purposes. For example, it may serve to select calling lines or trunks and to extend these lines or trunks to available outgoing circuits; it may serve to select idle lines from a group of equivalent lines for serving incoming calls; and it may serve to establish an indication of the designation of lines, trunks, or other circuits for message registration purposes or for the information of operators.

Although the invention is not necessarily limited to selection from groups of any particular size, it is illustrated herein as applied to a system for making selections from a group of one hundred lines. These lines are divided into ten digital groups I00, IOI, I09. Group I is the No. 0 tens group, that is, the group in which the tens digit of all ten lines is 0. Group IOI is the No. 1 tens group, and group I09 is the No. 9 tens group, the intervening seven groups having been omitted to avoid unnecessary repetition. The ten lines of each of these groups have the ten successive units digits 0 to 9.

The lines of all ten groups appear in the electrodes of the two series of selecting tubes 260 and 210. There are ten tubes in the tens series 260, these tubes corresponding respectively to the ten tens groups of lines. For example, tubes 200, I, 209 correspond respectively to the groups I00, IOI, I 09. Each tube has a main anode, a cathode and ten starting electrodes. The ten starting electrodes are connected respectively to the test conductors of the lines of the associated group. Likewise each of the ten units tubes is equipped with a main anode, a cathode and ten starting electrodes. The ten starting electrodes of each units tube are connected respectively to the test conductors of the ten lines having the same units designation. For example, the ten electrodes of the No. 0 units tube 2 I 0 are connected to the lines, one in each group, having the units digit 0. In the same manner the No. 1 units tube 2| I has its starting electrodes connected to the lines having the units digit 1; and the No. 9 units tube 2I9 has its starting electrodes connected to the lines having the units digit 9.

The cathodes 202, 203, 204 of the ten tens tubes 260 are connected to individual relays 205, 206, 201 and. thence through the common inductor 208 to ground. Similarly, the cathodes 2I2, 2I3, 2I4 of the ten units tubes 210 are connected through individual relays 2 I 5, 2 I 6, 2 I I and thence through the common inductor 2 I 8 to ground. The anodes of all tubes in the tens and units groups are connected over a common conductor 220 through the contacts of control relay 22I to the positive pole of battery 222.

The voltage for ionizing the tubes is obtained by the simultaneous application of potentials to the control electrodes and the main cathodes. Whenever it is desired to select one of the lines, a positive potential is applied to the test conductor thereof and over this conductor to the corresponding start electrodes of the corresponding tens and units tubes. This potential, however, is insufficient to operate either tube. The full ionizing voltage for the tens tubes is obtained by applying momentary impulses of negative potential to the cathodes during the time the starting electrodes are at positive potential. These impulses are produced by an impulse generator 250 which is energized by a source of alternating current 25I of any suitable frequency. The generator 250 produces ten negative impulses, often different phases, per cycle of the source 25I and applies these impulses over ten impulse conductors 252 to the cathodes of the respective tens tubes 260. Since these negative potential impulses are impressed consecutively upon the cathodes of the tens tubes 260, only one tube at a time will have full operating voltage applied to its starting gap. This insures that only one tube will operate, in the event a plurality of lines in difierent groups are in a calling condition at the same time. As soon as any one of the tens tubes discharges, current flowing in the common inductor 208 produces a voltage drop which lowers the potential applied to the cathodes of all tubes and prevents the ionization of another one thereof.

The impulse generator 250 may be of any suitable type, such as the generators disclosed in the application of W. H. T. Holden, Serial No. 361,536, filed October 17, 1940, and the patents to Holden, 2,285,815 of June 9, 1942, and 2,252,766 of Aug. 19, 1941.

The units tubes 210 are operated by voltages resulting from potentials impressed upon the starting electrodes by the calling lines and by the starting electrodes corresponding to calling lines in the operated tens tube and potential impulses impressed upon the cathodes of the units tubes by the impulse generator 250. The voltage resulting from the positive potential applied by a calling line to the starting electrode of a units tube and the negative potential impulse applied simultaneously to the cathode by the generator 250 is not suificient to operate a units tube, as it was in the case of a tens tube. However, since some one of the tens tubes has already operated, the discharge current flowing in the anode-cathode circuit raises the potential of all starting electrodes, connected to lines having the calling potentials thereon, to a positive value somewhat higher than that of the calling potential source. Since these electrodes of the operated tens tube are connected to corresponding starting electrodes in the units tubes, these units tubes have their starting electrodes raised to a positive potential which is sufficient to ionize the tube as soon as the negative potential impulse is applied to the cathode. Therefore, as soon following the ionization of the tens tube as the negative phase impulse is applied to a units tube which has been conditioned for operation by the operated tens tube, said units tube ionizes, and current flows in the main anode-cathode circuit. The flow of current in this circuit and through the inductor 2I8 produces a voltage drop which is immediately applied to the cathodes of the remaining units tubes to prevent the ionization of a second one thereof.

Thus it is possible to operate only one of the tens tubes and only one of the units tubes in response to a selectable condition on any one or on any plurality of lines. The operated tens tube results in the operation of the corresponding relay in the cathode circuit, and the operation of a units tube results in the operation of its individual relay. These relays serve to operate registers or other devices associated with the mech-,

anism 253 for the purpose of causing the automatic selection of the chosen line or for preparing information for message registration or for displaying the identity of the line at operators positions. For example, the register mech-' anism 253 may serve to control the operation of; automatic switches I03, I 04, I05, to eigtend the selected line to outgoing circuits.

The detailed operation of the selecting system will now be described. Assume for this purpose that calling or selectable conditions are placed simultaneously on lines IE and till in the tens group it?!) and on line I68. of the tens group IllI. These conditions may be applied by the operation of the individual relays Iii), Ill and H2. When relays H8 and HI operate, circuits are closed from the positive pole of battery i !5, through the contacts of these relays and resistors H3 and [Hi to ground. A positive potential is thus applied through resistor H'I to the starting electrode 223 representing the line H36 in the tube 200. Also positive potential is applied over resistor lit to the starting electrode 22d representing line in! in the tube. 290. Likewise the operation of relay H2 closes a circuit from positive pole of battery I59 through resistor lit to ground, and positive potential is applied over the resistor I2Il to the start electrode 225 representing the line H18 in the tens tube 2E6. Thus positive potential is applied at about the same time to three starting electrodes. two of which are in the No. 0 tens tube 238 and the other of which is in the No. l tens tube 29L If at this time the impulse generator 25.53 has already delivered a phase impulse over circuits 25 i and 255 to the tubes 2.00 and 20!, respectively, and is in the process of delivering impulses to the succeeding tubes in the group 256, neither of the tubes 2&6 and 2d! can operate until the source 25i enters its next cycle to repeat the phase impulses. When, however,- the next cycle commences, a potential impulse is applied through condenser 25% and resistance 257 and conductor 2% to the cathode 202 of the tube 26.53. This momentary impulse applied to the cathode 2% is of negative potential, and the voltage produced across the gap formed by the cathode 222 and the start electrodes 223 and 224 causes the tube to ionize. Immediately that the tube ionizes current flows in a circuit from the positive pole of battery 222, contacts of relay 222i, conductor 225), anode 22%, cathode E02, winding of relay 205, inductor 298 to ground. The flow of current in the inductor 2% produces a voltage drop which results in the immediate application of a positive potential to the cathodes 293, 204 of the remaining tubes in the group. Therefore, when the next phase impulse is applied over circuit 255 to the cathode 283 a moment later, the positive potential on the cathode 233 prevents discharge from transferring to the main anode 233 even if the starting gap ionizes momentarily. Similarly, succeeding tubes in the group are prevented from operating in response to the negative impulses in case their starting electrodes have been made positive by a calling condition on the corresponding lines. As soon as the discharge current flowing in the main discharge circuit of the tube 2&0 reaches a steady state, the inductive drop across the inductor. 28B disappears, but the resistance of this common element produces a voltage drop which maintains positive potential on the cathodes of the tens tubes to prevent a second. one from operating.

At the time relays I I0 and I I I operate the positive potential of battery H6 is applied to the starting electrodes 221 and 22B of the units tubes 2H! and 2 I I. Also the operation of relay I I2 applies positive potential from battery H9 to the starting electrode 229 of the tube 2| I. It will be noted that the impulse conductors 252 are also connected to the cathodes of the ten units tubes 210. Therefore, the application of a phase impulse over con u torl'iil to .thecathode 2I2 of tube 2III produces a voltage across the starting gap between the cathode 2I2 and electrode 221 which is equal to the sum of the negative impulse potential applied to cathode 2I2 and the positive potential applied to the electrode 221 and the same is true when an impulse of the next phase is applied over conductor 259 to the cathode 2I3 of the tube 2H. But the startinggaps of the units tubes require a higher voltage to produce ionization than the corresponding gaps of the tens tubes. Hence the units tubes do not ionize until some one of the tens tubes has operated.

When the tens tube 2% does operate, as above described, the starting electrodes act as collectors in response to the flow of current within the tube and the potential of each starting electrode which represents a line having a calling condition thereon is raised to a value considerably higher t a the potential applied as a result of the calling condition. For instance, the positive potential of the electrodes 223 and 225 is higher after current begins to flow within the tube than he potential applied to these electrodes from the battery M5. Thus the positive potential on the electrode 22? of the units tube 2th and the positive potential of the electrode 228 of the units tube lIi are raised to a value sufficient to cause ionization as Soon as a negative impulse is applied to the cathode of either one of these tubes. The positive potential of the electrode 229 of the tube iii remains at the value determined by the source I 99. After an interval following the conditioning of the units tubes Eid and 2H a negative impulse is applied from the generator 3253 to the cathode of one of these tubes. As-

suming that the next impulse is applied to the cathode 252 of the tube 2th, this tube ionizes its control gap, and immediately the discharge transfers to the main anode of the tube. Current now flows in a circuit from the positive pole of battery 222, contacts of relay 22L anode 230, cathode 2512, relay 2%, common inductor 2H3 to ground. The inductive drop produced by the element 2E8 alters the potential of the cathodes 2I3, 2M of the remaining tubes in the group 2% to prevent a second one of these tubes from operating. After the current in the discharge cirouit assumes a steady state, the resistance drop produced by the common lement iii? serves to maintain the cathodes of the remaining tubes sufficiently positive to prevent a second one from operating.

Relay 2535 in operating closes a circuit o-ver conductor 23! for operating in the mechanism 253 a registering or indicating device pertaining to the tens digit of the line iiiii; and relay 2I5 in operating closes a circuit over conductor 232 for operating a similar register in the mechanism 253 pertaining to the units digit of said line.

It will be noted that only those units tubes are rendered operable which represent the units digits of lines appearing in the particular tens tube that is in operated condition. This provision insures that the correct designation of the selected line will always be registered, because it is impossible to register the tens digit of one calling line and the units digit of a second line which is calling simultaneously.

When it is desired to release the selecting mechanism, relay 22i is operated in any suitable manner to disconnect the battery 2522 from conductor 22s. This causes the quenching of the operated tubes 2st and see and the release of the corresponding relays 255 and 2! 5.

v Fig. 3 shows an alternative circuit arrange ment for operating the tens and units tubes. Only one tube in each group is shown, the No. tens tube 3% and the No. 0 units tube 33L A single line 382 is also illustrated, appearing in the start electrode 363 of the tube 300 and in the start electrode 364 of the units tube 33!. Two relatively high resistors 3G5 and 306 are connected between the line conductor 302 and the cathode 3G1, and the mid-point of these resistors is extended through a resistor SE28 to the start anode 304. In a similar manner a pair of these high resistors are connected between the line conductor of each of the ten lines appearing in the tube 388 and the cathode 307, as indicated by the multiple tap 32 I.

When the line calls, relay 369 operates, and a circuit is closed from the positive pole of battery 3H1 over conductor SE32 through the relatively low resistor 3!! to ground. The positive potential of the battery 318 is also impressed over resistor 3 I 2 on the start electrode 393. Current also flows over line 392 through resistors 385 and 306, relay 3|3 and the common inductor 3M to ground. This current flow produces a given potential at the junctor point of resistors 305 and 306, and this potential is impressed upon the start electrode 304 of the units tube 33!. This potential, however, is insufiicient, when added to the potential impressed on the cathode 3H5 over the phase impulse conductor 3|6, to cause ionization of the tube 3!. As soon as the phase impulse is applied over conductor 3|! to the cathode 307 of the tens tube 360, this tube ionizes, and discharge current transfers to the main anode 3i8. Current now flows from the positive pole of battery 3I9, anode 3|8, cathode 361, winding of relay 3l3, common inductor 3M to ground. A positive potential now appears on the cathode 30'! which is sufiicient to cause current to flow through the resistor 336, resistor 305 and resistor 3 to ground. This current flow causes the appearance of an additional potential at the junctor point of the resistors 305 and 306, and the resultant potential at this point, and therefore the potential of the start electrode 384, is raised to a value which is sufficient to cause the operation of the tube 3! when a phase impulse is applied to the cathode thereof. When, therefore, the next phase impulse is applied over impulse conductor 3H5, the tube 3M ionizes, and current flows from the positive pole of battery 322, anode 323, cathode 3I5, winding of relay 324, inductor 325 to ground.

As in the circuits hereinbefore described, the flow of current in the tens tube 3% renders the remaining tens tubes ineffective; likewise the flow of current in the units tube 3lll prevents the operation of a second one of the units tubes.

If it is desired to reduce the potential applied to the starting electrode 304 of the units tube, a resistor 320 may be connected as indicated by the dotted line. The fiow of current through resistors 3G8 and 320 lowers the potential of the start electrode 304. However, the difference of the potential on this electrode when the corresponding line is calling and before the tens tube has operated and the potential on this electrode after the tens tube has operated is sufiiciently great to insure the selective operation of the units tube only in case the tens tube has operated.

What is claimed is:

1. The combination in a selecting system of a plurality of lines having digital designations, a

group of selecting devices corresponding respectively to the digit characters of a first digital place of the designations, a second group of selecting devices corresponding respectively to the digit characters of a second digital place of the designations, means responsive to a selectable condition on any desired one of said lines for causing the operation of the particular selecting device of the first group representing the first-place digit of said line, means effective upon the oper ation of said device for disabling all other devices of said first group to prevent the operation of a second one thereof in response to a selectable condition existing simultaneously on a second line, means effective upon the operation of one of said devices for rendering operative the particular device of said second group representing the second-place digit of said desired line, means effective upon the operation of said particular device of the second group for disabling all other devices of said second group to prevent the operation of a second one thereof corresponding to a second line having a selectable condition thereon, and means responsive to the operated devices for selecting and identifying the desired line.

2. The combination in a selecting system of a plurality of lines having designations, said lines being divided into a plurality of groups having difierent first-place digit characters, the lines of each group having different second-place digit characters, a series of selecting devices corresponding respectively to the first-place digit characters of said designations, a second series of selecting devices corresponding respectively to the second-place digit characters of said designations, means responsive to a selectable condition on a particular line in any one of said groups for causing the operation of the selecting device representing the first-place digit of the lines of said group, means effective in response to the operation of said device for disabling all other devices of said first series to prevent the operation of a second one thereof in response to the selectable condition of a line in the corresponding group, means effective upon the operation of any one of the devices of said first series for rendering operative the particular devices of said second series representing the second-place digits of all lines having a selectable condition thereon in the group corresponding to the operated device of the first series, means effective upon the operation of a particular one of the devices of said second series for disabling all other devices of said second series to prevent the operation of a second one thereof, and means responsive to the operated device of the first series and the operated device of the second series for selecting and identifying the corresponding line.

3. The combination in a selecting system of lines having digital designations, said lines arranged in a plurality of groups having different first-place digit characters, the lines of each group having different second-place digit characters, a series of discharge tubes corresponding respectively t the first-place digit characters of said designations, a second series of discharge tubes corresponding respectively to the secondplace digit characters of said designations, means responsive to the calling condition on any one of said lines for causing the operation of the discharge tube of the first series corresponding to the digital group containing said line, means responsive to the flow of discharge current in the operated tube for disabling the remaining tubes of said first series, means responsive to the flow of discharge current in the operated tube,

of the first series for rendering operative the tubes of said second series, means for operating a tube of said second series corresponding to the second-place digit of the line in the group represented by the operated tube of the first series, means responsive to the flow of discharge current in the operated tube of the second series for disabling the remaining tubes of said second series, and means controlled by the operated tubes for selecting the corresponding calling line,

4. The combination in a selecting system of a plurality of lines having digital designations, said lines divided into a plurality of digital groups, a series of discharge tubes corresponding respectively to the digital groups of lines, a second series of discharge tubes corresponding respectively to the digital designations of the lines in each group, means for applying a selectable condition to said lines, circuit means for impressing the selectable condition of said lines upon the corresponding tubes of said first series, means for producing impulses of a series of phases corresponding respectively to the tubes of both of said series, circuit means for impressing said impulses upon the tubes of said first series to cause the operation of the first tube therein having the selectable condition of a line impressed thereon, means responsive to the flow of discharge current in the operated tube for disabling the remaining tubes of said first series, means responsive to the flow of discharge current in the operated tube of the first series for rendering operative the tubes of said second series, circuit means for impressing said impulses upon the tubes of the second series to cause the operation of a particular tube therein corresponding to the digital character of one of the lines having a selectable condition thereon in the group corresponding to the operated tube of the first series, means responsive to the flow of discharge current in the operated tube of said second series for disabling the remaining tubes of said second series, and means for identifying the line corresponding to the operated tubes of the first and second series.

5. The combination in a selecting system of a plurality of lines divided into tens groups, the lines of each group having different units designations, a series of tens digit tubes, one for each tens group, each of said tubes having an electrode individual to each line in the group, a series of units digit tubes, one for each units designation in each group, each units tube having an electrode individual to a line in each of the ten groups, means for creating a calling condition on said lines, circuit means for impressing the calling condition of each line upon the corresponding electrodes of the corresponding tens tubes, means for producing impulses of difierent phases, said phases corresponding respectively with the tubes of both series, circuit means for impressing said impulses upon the tubes of the tens series to cause the operation of the first tube thereof having electrodes with the calling condition of one or more lines impressed thereon, means responsive to the fiow of discharge current in the operated tens tube for disabling the remaining tens tubes, the flow of discharge current in the operated tens tube also serving to alter the potential of the electrodes thereof to impress an operative potential upon the electrodes of the tubes of said units series, circuit means for impressing said phase impulses upon said units tube to cause the operation of the particular tube therein upon which an operative potential has been impressed by the electrode of the operated tens tube, means efiective in response to the flow of discharge current in the operated units tube for disabling the remaining units tubes to prevent the operation of a second one thereof corresponding to the units designation of a second line in the selected group having a calling condition thereon, and means responsive to the operation of the tens tube corresponding to the selected line group and to the operation of the units tube corresponding to the units designation of a particular line in said selected group for identifying said particular line.

WILLIAM H. T. HOLDEN.

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