US2471415A - Telephone calling line identification system - Google Patents

Telephone calling line identification system Download PDF

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US2471415A
US2471415A US485262A US48526243A US2471415A US 2471415 A US2471415 A US 2471415A US 485262 A US485262 A US 485262A US 48526243 A US48526243 A US 48526243A US 2471415 A US2471415 A US 2471415A
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line
relay
lines
contact
discharge device
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Deakin Gerald
Hatton William
Lucien A B Cabes
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International Standard Electric Corp
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International Standard Electric Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M15/00—Arrangements for metering, time-control or time indication ; Metering, charging or billing arrangements for voice wireline or wireless communications, e.g. VoIP
    • H04M15/08—Metering calls to called party, i.e. B-party charged for the communication

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  • the present invention relates to new and useful improvements in central office telecommunication systems and particularly to call-responding circuits which serve to detect a call or to identify the calling line.
  • One object of the invention is to provide a call-responding circuit adapted to serve a group of lines, such as subscriber, junction or other similar lines, which detects a call or identifies the calling subscriber or junction line, without the need of using an individual relay or switch for each subscriber or junction line.
  • circuits having switching mechanism of a standard type connect a call-responding discharge tube to a certain number of lines (subscriber lines or junctions, for example) in such a rapid sequence that the contact with each line is only momentary.
  • the discharge tube is so arranged as to operate more or less instantly upon the receipt of a call, and to continue in operation even after the release of the calling line. This will allow other slower equipment time to operate.
  • One particular object of the invention is to provide an arrangement wherein switching mechanism of standard type is actuated without interruption in order to connect the discharge tube to a certain number of lines in rapid succession and wherein the dis-change tube, upon being operated by a momentary contact, remains in action for a time sufi'icient mechanically to energize a movable switching device, such as a relay, for detecting a call among the lines served by said switching device.
  • a movable switching device such as a relay
  • Another object of the invention is to provide call finder circuits wherein a switching mechanism, for example, a line or junction finder, is placed in operation by a calling condition over a subscriber line or group junction, and begins immediately to connect momentarily a test equipment to each of the subscriber lines or group junctions in rapid succession.
  • the test equipment is immediately ready to respond to a calling condition without need of waiting for a warming up period.
  • Still another object of the invention is to provide responding equipment to detect a call or to identify the calling line which comprises one or more discharge tubes adapted to be operated by very small currents across high resistances associated with the different lines and designed to remain operated even after having been disconnected from said resistances.
  • Still another object of the invention is toprovide an installation wherein the responding 2 equipment comprises a discharge tube of the cold-cathode type that is constantly ready to operate without need of the heating power of the cathode.
  • the present improvement consists in that the discharge devices are so arranged as to continue operating after they have been operated once through momentary connection with a calling line, this extended operation serving to actuate a relay or other means requiring longer time.
  • the present invention afi'ords the possibility of operating at very high contact speeds the switching mechanism that connects the discharge device successively to the lines.
  • a switch particularly suitable for this kind of operation at high contact speeds has already been described in application Serial No. 389,352, filed April 19, 1941 by Deakin, now Patent No. 2,339,063, dated Jan. 11, 1944, although any high speed non-numerical finder switch may be employed.
  • the present invention respresents an improvement in that the potentials applied across the high resistance to the subscriber lines are so chosen that a slight resistance leak between one of said lines and the ground will simulate a call condition rather than put the line out of calling condition.
  • the present invention further represents an improvement in that the discharge devices are of the cold-cathode type, do not require filament heating current, and are always ready to operate without delay.
  • Fig. 1 shows a subscriber line circuit and a call responding circuit, as required in order to understand certain novel principles of the invention
  • I Fig. 2 represents another embodiment of the 3 invention comprising a subscriber line circuit, a line finder circuit and a call responding circuit for detecting a call, operating a line finder in response to the latter and stopping the finder when it reaches the calling line;
  • Fig. 3 shows still another embodiment of the invention comprising a subscriber line circuit, a line finder circuit containing an automatic stop device for a calling line, and a call responding circuit for operating a line finder chosen preferably as a result of a call condition in said line circuit;
  • Fig. 4 is a schematic diagram showing one of the ways in which a plurality of line finders a certain number of lines may utilize the embodiment of my invention shown in Fig. 3;
  • Fig. 5 is a modification of Fig. 2;
  • Fig. 6 is a modification of Fig. 4.
  • l is a substation equipment connected to a central exchange through a subscriber line 2 having two conductors a and b.
  • a grounded high resistance 3 is connected to conductor a of line 2
  • another high resistance 4 is connected between conductor b of this line and a detector switch 5 constantly rotating at a high contact speed, for instance, 120 to 600 con tacts per second.
  • the wiper of this switch 5 is connected to conductor 6.
  • Conductor 6 is normally maintained at a negative potential somewhat lower than -125 volts through a leak resistance 1 connected to the tap of a potentiometer 8 which, in turn, is connected to the terminals of a stabilized 1-25-volt source.
  • the moment wiper 5' passes over the contact con-- nected to resistance 4, the potential of conductor 6 is raised momentarily to a less negative value if the switchhook at station I is closed.
  • resistances 3 and 4 have a value of 10,0001 each, that line 2 has a loop resistance of 25001.0 and that the value of leak resistance 'l is 25,000w. Therefore, if the tap of potentiometer 8 is adjusted to 1l1- volts and if the resistance of this potentiometer is negligible, the potential of conductor 6 will become at this moment 55 volts.
  • a gas filled discharge device 20 of the cold-- cathode type has its control anode 2 l connected to conductor 6 through leak resistance 9 which may, for example, be of 500,00010, and its cathode 22 connected to the negative pole of the 125-volt source, the main anode 23 or this tube being con-- nected to ground through a relay 24.
  • this tube is of the type sold under the trade mark W. E. 313- and described in an article byIngram appearing on pages 34*2*346 of the Electrical Engineering Transactions, vol. 58, July 1939.
  • the critical breakdown voltage for the control space between electrodes H and 22 is assumed to be around '70 volts.
  • Fig. 2 shows another embodiment of the inven tion wherein a gas filled cold-cathode tube 20, like tube 20 of Hg. 1 is used, not alone to detect a call, but also to identify a calling line.
  • the arrangement shown in Fig. 2 comprises an individual subscribers line equipment i, 2, 3, i, In; a switch 5 common to a whole group of line equipments of this kind; a common detector equipment H a first line finder ILFI, which represents one out of a group of, say, 14 first line finders, and a distributor circuit 12 for connecting six wires from the common detector Ii to the first free first line finder.
  • Distributor [2 may be of any known type normally capable to maintain the common equipment H connected to a tree line finder and to transfer the connection to the next free line finder upon the operation of a relay 50 in the line finder to which the said distributor is connected.
  • Relays 25, 26 and 21 are supplementary telephone type relays in the common equipment ll; 50 is a similar relay in a line finder ILF I, while 5! is an electromagnetic clutch mechanism for operating the line finder.
  • Ill is a message register associated with the individual subscribers line but installed at the central office.
  • the circuit shown in Fig. 2 operates as follows: To start a call, the subscriber at station I lifts the receiver, which closes a circuit from ground via resistance 3, line 2 conductor a, line 2, conductor b, resistance 5, wire c, switch 5' (when the latter passes over its corresponding contact), left back contact of relay 2'5, conductor 6, leak resistance 1, upper portion of potentiometer 8*, to the 125 volt battery. In the same way as previously described with reference to Fig. 1, this circuit reduces the negative potential of conductor 6, so that control anode H becomes volts more positive than cathode 22, ionizing the control space of tube 20. Current flows from ground through the outer left-hand back contact of relay Bil, distributor I2, inner right-hand breaking contact of relay 2'5, winding of relay 2 main anode 23' and cathode 22 of tube 28 to the volt battery.
  • Relay 24 becomes energized and closes a circuit from ground through its front contact, righthand breaking contact of relay 26,- conductor 28, winding of relay 25 to the standard 4 8-volt central battery.
  • relay 25 breaks the contact between conductor 6 and switch 5 in its left back contact.
  • the right front contact of relay 25 connects the ground, through the outer left-"hand back contact of relay 50 and the corresponding distributor connection, to the Winding of relay 28 which, however, does not operate onaccount of the short-circuit to ground at the armature of relay 24.
  • the operation of relay causes the potential of the standard 48 volt central battery to be applied through its outer right-hand front contact, to conductor 29, and thence across resistance and the corresponding distributor connections to conductor 3
  • relay 25 opens the circuit of relay 24 and the main discharge space of tube 20. This stops the ionization of tube 20 and relay 24 falls back.
  • relay 25 After release of relay 24, the circuit of relay 25 is opened and current flows to ground via left back contact of relay 50, corresponding connection of distributor l2, inner right-hand front contact of relay 25, winding of relay 25, conductor 28, winding of relay 25, to the 48-volt central battery. Consequently, relay 25 holds and relay 26 energizes.
  • the operation of relay 26 causes the closing of a circuit from ground, the back contact of relay 24, outer front contact of relay 26, corresponding connection across distributor l2, clutch magnet 5
  • tube 20 which has been deionized, is in the same condition as before the call was started, except that conductor 6 remains connected through the inner left-hand front contact of relay 26 and through the corresponding connection of distributor I2, to Wiper c of the line finder instead of to the wiper of detector switch 5.
  • the ground potential across resistance 3, loop of line 2 and resistance 4 reduces the negative potential of conductor 6 sufficiently to produce a discharge across the control space of this tube, which, in turn, causes a discharge across the main space, energizing relay 24 as before.
  • the relay 24 opens the circuit of clutch 5
  • relay 2'! If relay 2'! is already operated, the circuit prepared for relay will be completed and relay 50 will operate. Otherwise, the equipment will wait until the ground is applied to wire 0''.
  • relay 50 breaks, at the outer left-hand back contact, the locking circuit of relays 25 and 26, which release.
  • relay 50 breaks, at its right-hand back contact, the circuit of relay 21, releasing the latter, but not without first locking up over its right-hand front contact to ground over wire 0".
  • the relay 50 connects the -125 volt battery via its inner left-hand front contact and wiper c to the 0 wire of the calling line, thus indicating that this line is busy and preventing the initiation of further calls when switch 5 again passes over the associated contact.
  • the relay 5!] now controls distributor l2 to connect the six wires of the common equipment When wiper c finds the con- 'H to the first free first line finder in any suitable manner. When the connection with this first free line finder is completed, the ground from the outer left-hand back contact of a corresponding relay 5!] is applied to the main anode 23 of tube 20, so as to make this tube ready to respond to another call.
  • Fig. 3 shows another embodiment of the invention wherein the detector switch 5 not only helps to detect a call, but also serves as a distributor, for determining which line finder must be operated to hunt for the calling line.
  • each line finder is equipped with a discharge device 40, like device 20 provided for the common equipment ll.
  • Each tube 45 serves not only as a control means for identifying the calling line during hunting, but also, in a preceding call phase, to cooperate with switch 5 for determining which line finder must be operated.
  • the switch 5 to be used in this embodiment should preferably be of the type described in application Ser. No. 389,352, filed April 19, 1941, issued U. S. Patent No. 2,339,063, Jan. 11, 1949, wherein a conductive ball I 4 is displaced and rolls over a series of stationary contacts I5 while it also rests upon a conductive ring.
  • this conductive ring is made up of a plurality of arc-shaped elements l6, l1, etc., all the arcshaped elements l6 being multipled with one another and connected to conductor 6, while all the arc-shaped elements I! (of which only one is shown) overlap and are connected to conductor 33.
  • switch 5' should be preferably shaped as a complete circle, although only a semi-circle is shown in the drawings for the sake of simplicity.
  • each line finder such as ILFI, comprises two relays 52 and 53 instead of the single relay 5! of Fig. 2.
  • the line finder switch itself comprises Wipers a, b, c and d and an electromagnetic clutch 5
  • Each line finder such as ILF-l, further comprises variable resistance 36 and fixed resistances 3'7, 38 and 39, suitably connected to line finder discharge tube 40.
  • the standard equipment II is the standard equipment II,
  • F in addition to tube 20 and resistances 5, l, 8 and 9, which are the same as in Fig. 1, comprises two supplementary resistances 34 and 35.
  • the embodiment shown in Fig. 3 operates as follows: When the switchhook is lifted at substation I, then at the next passage of ball 14 over the corresponding contact I5, the ground potential passes through resistance 3, loop of line 2, resistance 4, line wire 0, proper contact [5 of switch 5', ball [4 and bank I5 of this switch, conductor 6, resistance 1, upper portion of potenti-' ometer 8, to a tap of volts on a stabilized potential source of volts. Exactly as in the embodiment shown in Figs. 1 and 2, this ground potential ionizes the control space of tube 20, which in turn fires the main space between cathode 22 and main anode 23 of this tube.
  • Resistsince 35 may have 3i. value of 2230001. It corresponds substantially to relay 2,4 of Figs. 1 and- 2.
  • Resistance 34 has a high value, of 1300,0001, for example, and the voltage drop due to the flow of discharge current. through this resistance strongly shifts the potential of cathode 22 and of conductor 33 in the positive sense in such a way that this potential instead of being of ll251volts, may, for instance, be of -'75 volts.
  • bank l'l of switch 5 which. normally has a potential of 125 volts, has. its potential raised to 75 volts when ball 14- passes over the contact connected to the wire associated with the calling line.
  • Ball I24 continues toroll clockwise on the rim of the switch, leaves bank t6. and starts making contact between bank H and the contacts l associated with the various line finders provided tor the group of lines connected to this switch. If the line finder connected to the first of these contacts l5 is already busy, the conductor runfrom contact. l5 will be opened at back contact of 54 and, consequently, the passage of the ball over said contact l5. will have no effect. Let us assume, however, that line finder ELF-l associated with the first contact i5 is free. Then, when ball l4. establishes a connection between said contact 15 and bank ll, the -75 volt potential now existing on bank ll will be transmittedvia ball l4, contact l5, back.
  • resistance 38 to. the -l volt terminal of a stabilized potential source Assuming that resistance 38 has a value of 500,000w, this resistance will cause only a very small variation of potential in bank I? and hence conductor 44 likewise will be brought ver nearly to 75 volts.
  • the control space of tube 40 will be ionized, because the cathode it of this tube is. connected directly to a l80. volt potential source, While anode M is connected via resistance 31 to conductor 44, which is very near to 75 volts.
  • the value of resistance 31 may be 500,000w.
  • relay 52 has an inductive winding Working into a non-inductive winding shunted thereto, the resistance of these windings being 1050aand 800w, respectively.
  • bank I! will nevertheless be, brought almost instantly to such a potential that it will be incapable of causing the ionization of other tubes, such as tubes 40 of the succeeding line finders.
  • the outer left-hand front contact of relay 52 connects anode 43 of tube 50, to test relay 53, but this contact is at a great distance from the outer left-hand back contact, so that tube 45 is de-ionized during the passage of the armature between these contacts.
  • a resistance 39 which may be of 20,00Qw, is inserted' in order to bring anode 43 promptly to the same potential as cathode 52.
  • the inner right-hand front contact of relay 52 applies ground potential to a conductor 6
  • the outer right-hand front contact of relay 52 closes a circuit for the ground comingfrom the outer left-hand back contact of relay 53, outer right-hand front contact of relay- 5-2, clutch 5
  • causes the rotation of line finder wipers a, b, c and d.
  • tube 40 is now deionized and has its cathode 42 connected to 180 volts, while its control element 4
  • Wiper c finds the contact associated with the calling line, a circuit is closed from the ground, v-ia resistance 3, loop of line 2, resistance 4, wire, wiper c, resistance 35, onnormal contact 54, conductor 44, leak resistance 38 to the 125 volt terminal of the ISO-volt battery.
  • Resistance 36 is adjusted to such a value that, for any loop whatever of 2,500 to or less, the potential of conductor 44 is displaced negatively just sufficiently for ionizing the control space of tube 45.
  • the outer left-hand back contact of relay 53 breaks the circuit of clutch thus stopping the line finder switch on the calling line.
  • the inner left-hand front contact of relay 53 applies the -125 volt potential through wiper c to a 0 wire of the calling line in order to indicate that th latter is busy and prevent this line from starting another call.
  • this potential returns control anode 4
  • relay 53 breaks the locking circuit of relay 52 and causes a potential drop in resistance 35, which puts the latter out of operation.
  • Relay 52 is then released and tube starts operating again. The release of relay 52 de-ion-izes tube during the transfer from the outer left-hand front contact to the outer left-hand back contact of this relay.
  • Line finder ILF-I is now connected to the calling line, with tube 20 and relay 52 returned to normal. Only relay 53 remains energized from .a 48-volt battery applied from the succeeding portion of the connection (not shown). Once the call has ended, this battery connection is momentarily or permanently interrupted by any suitable means to release relay 53. The ground through the outer left-hand back contact of relay 53 and off-normal contact 55 energizes clutch 5
  • switch 5 has been shown semi-circular in Fig. 3, and only two banks i5 and one bank I! are illustrated. How ever, this switch is preferably of circular shape and is provided with several banks ll located between several banks l6.
  • One of the important features of the invention is the use of one and the same switch for detecting a calling line and for starting immediately thereafter the hunting of a free line finder to hunt for the calling line.
  • the system diagrammatically illustrated in Fig. 3 is very flexible and may be arranged to give many different solutions in the distribution of the line finders.
  • Fig. 4 shows one of the ways in which 6 line finders and 48 lines can be associated with one switch, such as 5', serving both for detecting a call and for distributing the calls to the line finders.
  • , ILF--2, ILF-5 are connected to twelve contacts located in front of six arc-shaped segments while the;48 lines are connected in groups of eight each to contacts located in front of six arc-shaped segments I6. It is assumed that ball I 4 rolls clockwise in the switch of Fig.
  • upon being operated, starts hunting over line LI and hunts successively over lines Ll, L2, L3, L4, L41, L48, while line finder ILF2 starts hunting on line L9 and hunts successively over lines L9, Llfl, L
  • Fig. 4 it will be seen that if a call is made in line group Ll L8, so that discharge tube 20 of the common equipment I will be ionized when ball
  • each line finder will appear only once in the bank of switch 5' it may also be used with multipling in order to reduce the distribution time for a finder to be chosen in second place.
  • line finder ILF-I may be connected between LI and L48, but also to the last one tested of two contacts between L9 and L8.
  • ILF-2 likewise would be connected to the first of the two contacts tested, first between L9 and L8 and also to the last one tested of the two contacts between Lll and Ll6. The same applies to the other finders.
  • FIG. 6 Another arrangement of the line finders with respect to the lines is shown in Fig. 6, wherein 4 banks I1 are used, each having eight distribution contacts associated with it, and wherein the eight line finders are so multipled that each appears in each one of the four distribution contact groups.
  • the ball would roll counterclockwise and the finders would hunt over the lines in ascending numerical order from four difierent normal positions.
  • the order in which the eight line finders would appear in the group of eight contacts located between LI and L48 could be as follows, (counting counter-clockwise, i. e., in the direction of rotation of ball l4) ILF--l, ILF5, ILF4, ILF8, ILF-3, ILF4, ILF2, ILF6.
  • the corresponding order in which the eight line finders will appear in the group of eight contacts located between LIB and LIZ is as follows (counter-clockwise) ILF--6, ILF-2, ILF--5, ILF-l, ILF-B, ILF-4, ILF!, ILF3.
  • the order of appearance of the line finders of the other contact groups should likewise be such that, after having passed over any one line group, ball l4 would test first those line finders whose hunting time is a minimum for the said line group and then test those line finders having the next shortest hunting time.
  • 4 banks I! have been mentioned, a larger or a smaller number may be used.
  • the line finder off-normal contacts should be arranged preferably so as to stop the finders only in three different normal positions.
  • each line finder may be multipled two or three times, without thereby multipling it so completely that it will appear in front of each bank 11.
  • the principle on which the several line finders are operated simultaneously may be combined with the principle of operating a single line finder chosen in advance.
  • the above described selective distribution principle may be used for determining that a certain pair of line finders (for instance, ILF-3, ILF7) be the nearest ahead of the calling line group (for example, L25, L26 L36) and then the principle of simultaneous operation may be applied by operating the two line finders thus brought nearest if both of them are then free.
  • a certain pair of line finders for instance, ILF-3, ILF7
  • the principle of simultaneous operation may be applied by operating the two line finders thus brought nearest if both of them are then free.
  • Each of the six line finders could then be multipled so as to appear four times, but being arranged in variable sequences in front of four segments ll. Assuming that the normal positions of the first four line finders are L48, Ll2, L24 and L36, respectively, and assuming that the ball. rolls counter-clockwise while the line finders hunt over the lines in numerical order startin from the various above-mentioned, normal positions, the six line finders could then be connected to the six distribution contacts located between lines Li and L48 in the following order (counting counter-clockwise) ILFI, ILF-4, ILF-3, ILF2, ILF5, ILF-6. In like manner, the six line finders may be connected to the six distribution contacts located between lines M3 and H2 in the following sequence (counting counterclockwise) ILF-2, ILF-l, ILF-4, ILF-3,
  • the correspondin order of appearance of the finders would be ILF-4, ILF--3, ILF2, ILF-l, ILF5, ILF--6.
  • the first line finder to be chosen for a line group would always be one of the first four that can find the line faster.
  • the second to be chosen would be that one of the first four that is nearest ahead of the line and so on, but in all cases line finders ILF-5 and ILF-6 will be the last to be chosen and will be able to operate only if the other four are busy.
  • the discharge device preferably used in the above described embodiments is a gas filled cold-cathode tube, normally maintained in non-ionized condition
  • automatic blocking discharge devices of other types may be employed.
  • a screen grid high vacuum thermionic tube may be used with one of the known automatic blocking connections which serve to keep the tube in an abnormal conductive or blocking condition after the tube has been brought to this condition by momentary application of a calling potential to its grid.
  • a device of this type is shown in Fig. 5.
  • a gas filled hot-cathode tube may also be used, since this tube is also of the automatic blocking type and will remain ionized momentarily after having been brought to this condition by a momentary signal on its grid. It will be understood, however, that it is preferable to use a gas filled cold-cathode tube according to my invention and to operate it so that normally it will be de-ionized, but biased in such a way as to be capable of maintaining the ionization as described above.
  • the ground potential is applied to the far side of each finder, i. e., to the conductor of the line loop that is not connected to the fast-rotating detector switch.
  • a telecommunication system a plurality of lines, a discharge device, a switching mechanism, means for operating said mechanism for successively connecting said lines to the discharge device, means operative upon the connection of the device with the calling line for actuating said discharge device, means controlled by the device for stopping said mechanism, and means independent of said switching device for maintaining said discharge device operated.
  • a switching mechanism for successively connecting said lines to the discharge device, said switching device having two sets of cooperative contacts, to the first of which said lines and to the second said discharge device are connected, means for moving said sets of contacts with respect to one-another, means operative when the second set of contacts and the contacts of the first set with which a calling line is connected come into engagement with oneanother for actuating said discharge device, means controlled by the device for stopping the relative movement of the contacts, and means for maintaining said discharge device operated after the separation of said contact sets.
  • a telecommunication system a plurality of lines, a discharge device, a switching mechanism for successively connectin said lines to the discharge device, said switching mechanism having a brush to which said discharge device is connected and a set of terminals to which said lines are connected, means for moving said brush to Wipe over said set of terminals, means operative when the brush engages the terminals of a calling line for actuatingsaid discharge device,
  • said discharge device is a gas filled coldcathode tube which is normally non-ionized but biased to such a potential that it remains ionized once the ionization has started, and means for starting the ionization upon the connection of the discharge device with a calling line.
  • a plurality of lines a first discharge device, a switching mechanism for successively connecting said lines to the discharge device, means operative upon the connection with calling line for actuating said discharge device, means independent of said switching mechanism for maintaining said discharge device operated, a trunk line, a switch for connecting the calling line with said trunk, an operating circuit for said switch, and a second discharge device controlled by the first discharge device and controlling in turn said circuit.
  • a telecommunication system a plurality of lines, a discharge device, a switching mechanism for successively connecting said lines to the discharge device, means operative upon the connection with a calling line for actuating said discharge device, means independent of said switching device for maintaining said discharge device operated, a trunk line, a line finder having a brush in which said trunk line and terminals in which said lines terminate, a magnet for moving said brush over said terminals in succession, a circuit for said magnet, means for closing said circuit upon the actuation of said discharge device, and means controlled by said device for opening said circuit when the brush engages the terminals of the calling line.
  • a plurality of lines divided into groups a discharge device, switching mechanism for successively connecting a group of lines to the discharge device, said switching mechanism having a row of terminals in which a group of lines terminate and a brush to which the discharge device is connected, means for operating said brush continuously to wipe over said terminals in succession, means opera-.
  • a discharge device for successively connecting a group of lines to the discharge device, said switching mechanism having a row of terminals in which a group of lines terminate and a brush to which the discharge device is connected, means for operating said brush continuously to wipe over said terminals in succession, means operative upon the engagement of the terminals of a calling line by the brush for actuating said discharge device, means for maintaining said discharge device operated after the brush leaves the terminals of th'ecalling line, a trunk line, a line *finder 'for connecting a calling line with the trunk line, said line finder having 'a brush in which said trunk line terminates and terminals in which a group-of :sai'd lines terminates, a circuit for operating the brush of said switch to wipe over the cooperating terminals, and means controlled by said discharge device for closing and opening said circuit.
  • a plurality of lines divided into groups a discharge device, a switching mechanism for successively connecting a group of lines to the discharge device, said switching mechanism having a row of terminals to which the groups of lines are connected in a predetermined order and a contact, a connection between said contact and the discharge device, means for operating said contact continuously to wipe'over said terminals in succession, means operative upon the engagement of the terminals of a calling line by the contact for actuating said discharge device, means for maintaining said discharge device operated after the contact leaves the terminals of the calling line, a plurality of line finders, each having a brush, terminals to which said lines are connected in different order, two special terminals for said switching device between the terminals-of adjacent groups, a magnet for each line finder to operate the brush to wipe over the line terminals in succession, a circuit for each magnet, each circuit including a different special terminal of the switching device, and all the circuits including a contact controlled by the switching device.
  • a plurality of lines divided into groups a discharge device, a switching mechanism for successively connecting a group of lines to the discharge device, said switching mechanism having a row of terminals in some of which said groups of lines terminate and a contact to which the discharge device is connected, means for operating said contact continuously to wipe over said terminals in succession, means operative upon the engagement of the terminals of a calling line by the contact for actuating said discharge device, a plurality of line finders for extending connections from calling lines, a circuit for selecting said line finders for operation in a predetermined order, said circuit including the contact and terminals of said switching mechanism.
  • a plurality 16 of lines divided into groups a dischargedevice, a switching mechanism for successively connecting a group of lines to the discharge device, said switching mechanism having a row of terminals in some of which said groups of lines terminate and a contact to which the discharge device is connected, means for operating said contactcontinuously to wipe over said terminals in succession, means operative upon the engagement o'f the terminals of a calling line by the contact for actuating said discharge device, a plurality of line finders for extending connections from calling lines, a circuit for selecting said line finders for operation in a predetermined order, said circuit including the contact and terminals of said switching mechanism and said discharge device.
  • a plurality of lines divided into groups a discharge device, a switchin mechanism for successively connecting a group of lines to the discharge device, said switching device having a row of terminals in which said groups of lines terminate and a contact to which the discharge device is connected, means for operating said contact continuously to wipe over said terminals in succession, means operative upon the engagement of the terminals of a calling line by the brush for actuating said discharge device, a plurality "of line finders for extending connections from calling lines, a circuit for selecting a, line finder for operation including terminals of said mechanisms, a discharge device associated with each line finder, and means jointly controlled by the first-mentioned discharge device and the discharge device associated with the selected line finder for stopping the latter on the calling line.
  • a switching system a plurality of lines, a plurality of switches each having a'bank of multipled terminal sets in which said lines terminate, and a set of wipers arranged to wipe over said terminals, magnets for controlling the movement of the switch wipers, sources of potentials of various characteristics, connections for placing characteristic potentials on terminals of lines depending on their condition, a multi-electrode electric discharge device, a first circuit for applying a potential to one electrode, a second circuit for applying to a second electrode the potentials existing on the terminals engaged by said wipers, said device being adjusted to operate when the potentials applied over the two circuits bear a predetermined relationship to one-another, and means actuated upon the operation of the device for controlling said magnets to stop the wipers.
  • the device is a gas-filled discharge tube having a cold cathode in the first circuit, a control anode in the second circuit, and a main anode connected with a relay constituting the last-mentioned means.
  • the device is a gas-filled tube having a cathode in the first circuit, a control grid in the second circuit, and an anode connected with a relay constituting the last-mentioned means.
  • ' 17 means independent of the second circuit for maintaining said device actuated.
  • a plurality of lines a plurality of non-numerical finder switches each having a bank of multipled terminal sets in which said lines terminate, a set of wipers for each switch cooperating said terminal sets, said sets of wipers and terminals including one for testing, a magnet for each switch and a circuit therefor controllin the movement of the switch wipers, a source of DC.
  • means for placing characteristic potentials on the test terminal of a line depending on its calling, idle or busy condition means including a multi-electrode electric discharge device for causing one of the switches to hunt for the calling line, a first circuit for applying a potential to one electrode, a second circuit for applying to a second electrode the potentials existin on the test terminals over the test wiper of a switch, said device being adjusted to operate when the potentials applied over the two circuits bear a predetermined relationship to one-another, means coincident with 18 r the operation of the device for altering the pctential on the test terminal, and means actuated upon the operationnof the device for controlling said magnet circuit to stop said wipers.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Monitoring And Testing Of Exchanges (AREA)
US485262A 1940-05-22 1943-04-30 Telephone calling line identification system Expired - Lifetime US2471415A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2576097A (en) * 1945-07-23 1951-11-27 Int Standard Electric Corp Automatic telephone selective switching system
US2604540A (en) * 1949-09-13 1952-07-22 Bell Telephone Labor Inc Calling line identification for automatic ticketing systems
US2697140A (en) * 1949-12-20 1954-12-14 Bell Telephone Labor Inc Electronic testing system

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2242776A (en) * 1939-04-25 1941-05-20 Bell Telephone Labor Inc Telephone system
US2295032A (en) * 1939-07-24 1942-09-08 Int Standard Electric Corp Communication exchange system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2242776A (en) * 1939-04-25 1941-05-20 Bell Telephone Labor Inc Telephone system
US2295032A (en) * 1939-07-24 1942-09-08 Int Standard Electric Corp Communication exchange system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2576097A (en) * 1945-07-23 1951-11-27 Int Standard Electric Corp Automatic telephone selective switching system
US2604540A (en) * 1949-09-13 1952-07-22 Bell Telephone Labor Inc Calling line identification for automatic ticketing systems
US2697140A (en) * 1949-12-20 1954-12-14 Bell Telephone Labor Inc Electronic testing system

Also Published As

Publication number Publication date
CH266247A (fr) 1950-01-15

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