US2191913A - Telephone system - Google Patents

Description

Feb. 27, 1940.

B. F. LEWIS TELEPHONE SYSTEM Filed March 3, 1939 3 Sheets-Sheet 1 //V VENTOR Bf. LE W/S Feb. 27, 1940. a. F. LEWIS TELEPHONE SYSTEM Filed March 3, 1939 3 Sheets-Sheet 2 Q (H QN I I1 l\l III a. I 3 M H R Q. 1 8 N@ m V 8 8 V R an I IN I W 6? /N VENTUR B. F. LE WIS 1 A TTOR/VEY Feb. 27, 1940. B. r. Laws TELEPHONE SYSTEM 3 Sheets-Sheet 3 Filed March 3, 1939 3 6 NON- L INEAR EL EMENT I la- ML Q E K n m A WM 7 u J r k JP A? 4U HNUUHHUUU T U U HF H 9 8 w w W T FIG. 7

Patented Feb. 2'7, 1940 nunirso sT ArEs hirer rricn vclaims. (01. 179-16) This invention relates totelephone systems, and particularly to signal sending and receiving arrangements' in automatictelephone systems;

It isan object of the present invention, to im 5 prove and simplify mechanisms for transmitting,

receiving and recording digit designations; I

f Another object is, to employ designations that are comparatively freefrom line disturbances.

Heretotore systems have been employed: in which digit designations have consistedof: har monies of a fundamental frequency specially selected to represent telephone designations, and i different methods have beenproposed for recording these designations.

vide means for representing digit designations by harmonics modified as to energy levels, each digit comprising a combination of signals; and; the various signals comprising harmonics that are modifiedasto their energy levels. j

Ancther feature of the'invention is to provide a'receiving and recording mechanism for said signals including thermionic tubes biased. to becomevactive in response to corresponding signals and recording means controlled by said tubes to record the signals as corresponding digit designations. v .v

The invention has. been: illustrated inrthe accompanying drawings in which Figs. 1 to 7 show various detailsaof an impulse transmitting mechanism. and recording the invention. 7 I

Of these figures, Fig. 1' shows a general assembly of the transmitter with certain" portions of the housing removedi Fig. 2- shows the commutator drums" and brushes to modify circuits to produce digit impulses;

Fig. 3 shows details of a locking device for the 40 drums; I I v 4, 5 and 6 show variousdetails; of the brush and contact arrangementsiin different positions;

Fig. '7 shows the arrangement of the contact elements on a drum; and

Fig. 8 shows a diagrammatic representation of digits. tension 5 on the right side thereof on which the. digits are marked}, and in the housing I there Itis a feature of the present invention to'prodevices in accordancewith separated sufiiciently to provide insulating por- "tions between them and between the rows. The

width of the contacting elements is practically equal to the insulation spaces between the four r0ws, as shown in Fig. '7. At the right-hand end of each drum there is provided a handle 4 that projects through an opening 5 in the housing i and bymeans. of which the drums may be set in thesetting of the drums to select eight succeeding Each drum is. also provided with an exis a. window for each drum such as window 8' so located inv relation to the legends on the drum that when the drums aremoved, the legends will be visible through the windows. At the top of the housing i there aretlocated two springs'ii and. Iii for each drum that always engage two special contact strips on the drum so that no matter in what positions the drums are set, these. brushes 9 and, It will always connect with certain contact elements. The contact strips may be. connected by any suitable means such as connecting wires in the manner shown in Fig. '7 to establish diiTe-rent combinations of connections between the contact elements-and the brushes 9 i or ill as determined by the setting of the drums.

The purpose of these connections will becomef apparent as'the description proceeds. At the edge of the extension ti of each drum there are a number of notches it as illustrated in Fig. 3 one-of which'may be engaged by a" projection I2 for each drum- These projections extend from a 3 bar I3 operated by a lever, arrangement Hi and held by a spring I5 in such a position that all drums are locked bythe projections i2 engaging the notches II inthe drums. The lever may be connected by. any suitablemeans such as the bar to the switchhock in the regular telephone set ,at the subscribers station so that when the receiver is on the switchhook the bar ii is depressed and moves lever It and bar I3 to remove the projections i2 from notches H to permit-the drums to be rotated for the setting of the various digits. [At the bottom of the housing I there 'is locateda brush carriage arrangement comprising a rack 28 anda pinion 2i engaging-this rack and v rotatably secured at one end by means of a shaft 22 to adisc23fslidably mounted on bar 24'. The rackj20f and bar 2 3v are" supported at both ends of the housing in suitable bearings such 'as 25 at one end and 26 at the other. The shaft '22 extends into a housing 30 and is connected to the inner end of a spiral spring 32, the other end of which is connected to the housing 33. This housing in turn is connected by the supports 33 and 34 to the disc 23. On disc 23 there is mounted a 3 bracket 35 supporting a lever 36 having a knob 38 extending outside of the housing I through 1 a slot 40. The disc 23 also supports the flexible brush member 42 which is insulated from the 1; disc 23 but is provided with a brush 44 for en- 'gagement with the drums as will be described hereinafter. This member 42 has an extension 46 that engages the end 41 of the lever 36. The

purpose of these parts, as illustrated in Figs. 4 to 6 in detail, is to provide means whereby the brush 46 may be swept transversely over the drums in succession when the drums have been set. Attached to the disc 23 is also three pairs of spring contacts 56, 5! and 52 that are operated by a lever 53 as will hereinafter be described. This lever is actuated by a projection 54 attached to thehousing near the left-hand end thereof.

Another pair of contacts 55 are operated bya lever 56. This lever is actuated by the two pro- J'ections 58 and 59 in succession. The contacts engages the various slots ll indrums 2 to lock 1 them in actuated positions. The subscriber then listens to dial tone which is produced as will presently be described. When dial tone is heard the subscriber engages the knob 38 of the lever release the knob 38 and the tension of the spring 36 and rotates this lever on its pivot to disengage the brush M from contact with the drums and then moves the lever, the disc 23 and the associated apparatus towards the left looking at Fig. 1. This will rotate the ratchet 2! on the rack 20 and thus cause the spring 32 to be wound up in the housing 30. When the subscriber has moved these parts all the way towards the left, he will 32 will then return the parts to normal as the spring 32 will act on the pinion 2| to rotate it back over the rack 20. A speed governing device (not shown) may be employed to regulate the speed at which the pinion is rotated back over rack 20. As soon as this mechanism is released the brush 44 will contact with and sweep over the drums transversely and engage the contact segments as encountered. It should however be.

noted that immediately after the disc 23 left the normal position the lever 53 will be engaged by the projection 54 and this lever 53 will thereby be swung over in an operative position toward the right as illustrated in Fig. 4 to cause the springs 50 t0 be closed, 5! to be opened and 52 to be closed. Immediately after the disc starts on its return to normal lever 56 will be engaged in succession by projections 58 and 59, as illustrated in Fig. 5, thus causing the contacts 55 to be opened-twice in succession. When the disc-23 has completely returned to normal the lever 53 will be returned to normal position by engaging the projection 54 and thus restore the springs 50, 5|

and 52 to normal position. When the conversation is completed the switchhook is replaced which causes the bar ll, lever M, bar l3 and projections 12 to be restored to release the drums. The drums'may then be returned to normal as left in the positions in which they have been set a as desired.

In Fig. 8 the impulse sending mechanism. described above has been disclosed in diagrammatic form showing drums 2 with contacts 9 and i6 engaging them, the lever 36 and the contacts 53,

as will. hereinafter be described. The line from the subscribers set is marked 66 and extends to a line finder 61 which has been shown "in dia-. grammatic form. The line finder may be connected to a registering device 68 shown below the dash-dotted line. This registering deviceincludes a number of difierent circuits and apparatus such as the filter 69, amplifier-detector and gain control devices 10, vacuum tubes H and 12, a steptacts 55'and 62, the transmitter and the right-' hand winding of induction coil 63 and causes the line finder 61 to connectthe calling line 36 to a central ofiice sender in the. usual manner. This connection then extends over leads 18 to a first selector-which has not been shown as apparatus of that kind is well known in the art. However, prior tothe extension of a connection over this first selector operations may take place in any manner'well known in the art to establish over leads 18 a connection through the usual sender connector to the registering apparatus 68. When this connection is made the-relay 86 is operated in any well-known manner toprovide certain locking circuits as will hereinafter be described. Relay 83 is also operated over the direct curr'ent circuit now established from'battery and ground through the windings of this relay, the tip and ring connection through conductors 13, line finder 61, conductors 66, contacts 55, the lower set of the switchhook contacts 62, the transmitter and the right-hand winding of induction coil 63. Relay 83 in operation closes a circuit for relay 84 which looks to ground at contacts of relay. 80.

The purpose of relay 84 will become apparent as the description proceeds. It should also be noted that alternating current from the hundred cycle source 85 is now also connected back to the calling line. The resistance 83 is inserted in series with source 85 to limit the volume of the current from this'sourceso as to make it suitable as a dial tone for the subscriber's receiver.

The contacts 9 and IQ of the various drums are connected to certain contact elements of the drums as seen in Fig. 7. When the subscriber hears the dial tone the transmission of the selected digits may begin. To this end the subscriber will now engage the knob 38 of lever 36 and remove. the brush 44 from connection with the drums and move the brush carriage all the way towards the left and then release the lever 38 at which time the brush 44 engages the first drum ready for the transmission of the impulses as determined by the settings of these drums. The first efiect, however, of the movement of the carriage towards the left is that the projection 54 will engage the lever 53 to close contacts 59 and 52 and open contacts .51, then when the carriage starts on its return to normal, the contacts 55 will beopened twice in succession by the projections 59, 59 to open the connection to the register 68. The immediate result of the first opening of the connection between contacts 55 is that the direct current connections completed on the'removal of the receiver from the switchhook opens the circuit from battery and ground through the windings of relay 83 over the conductors 19 and 66. The release of relay 83 closes the circuit for relay 81 from battery, winding 01? this relay and contacts of relays 83 and 84 to ground. Relay 88 is also operated on the release of relay 83 over a circuit from battery, winding of this relay and contacts of relays 89, 83 and 84 to ground. When relay 83 operates after the first operation of the connection at contacts 55, relay 89 will be operated from battery, winding of relay 88, contacts of this relay and relay 81, winding of relay 89 to ground at relay 84. Relay 8! is slow in releasing so it does not release at this time. When the relay 93 releases in response to the second opening of the contacts 55, relay 9!! will operate from battery through the winding of this relay, contacts of relays 89 and 83 to ground at relay 84. Relay 99 in operating", removes ground at its outer right-hand armature and back contact to enable the tubes H and I2 tooperate as will be described hereinafter. This relay also closes a shunt across the'resistance 86 and consequently the full effect of the alternating current from the hundred cycle source at 85 is transmitted back over the line. Relay 99 looks to ground and contacts of relay 3 3.

Now it should be observed that the next step will be that the brush 44 will proceed to travel transversely over the drums in succession and contact with the segments in accordance with the setting of the drums. However, before the brush M engages any contact segment of the first drum, it touches insulation and there is no connection through contacts 9 and Hi to brush Consequently, at this time the non-linear element 65 is shunted across the left-hand winding of the induction coil 93 in place of the receiver and receives the hundred cycle energy from the line by the transformer action of the induction coils 63 and 92. The non-lineal characteristics of element 65 cause this energy to be transformed into certain harmonics which are transmitted back to the line by. the induction coil. The eifect of this transmission is aided by the condenser 93. These harmonics are transmitted back over the'line at a certain normal energy level. The arrangement in register 68 is such that these harmonics willcause the switch 13 to take one step each time they are applied to the register after the circuit begins to function and'it is for that purpose that they are applied to the line before the brush 44 engages each row of segmentsin each drum. These harmonies are then modified by the segments encountered 'on the drums in their various settings to either be reduced in their energy levels to an intermediate value or be extinguished to produce,'as will hereinafter be explained three difpractically negligible value.

vferent effects. To effect the two last-mentioned energy levels the non-linear element may either be partially shunted by connecting one side of this element through the brush 44 tocertain contact elements in the drum through the brush [0 and the resistance 94. This produces harmonies ofv an energy level lower than the normal level. ment may be directly shunted by a connection established by the brush 44 through certain other contact elements in the drum and brush 9. This reduces the energy level of the harmonics to a It is by combinations of these various harmonic outputs that digits may be built up and it will now be described how this is effective in register 68'.

It should now be observed that normally there may be applied a positive potential by the am plifier-detec-tor and gain control devices 19 in any manner well known in the art to the grids v96 and 91 over the conductor 98 and individual resistances 9.9 and l99.- This normal potential is effective to operate the two tubes "ii and 12 as soon as relay 99 is operated as described by the removal of ground on lead 98 at the outer right-hand armature and back contact of this relay. The cathodes of the two tubes are biased at different negative potentials by being connected at different points as shown on the potentiometer circuit at I9], so that tubes H and 'lz'will operate depending on difierent values of the potential existing on the conductor 93. Such values are first the normal positive potential from the amplifier-detector and gain control devices. 19 which causes the tubes to become active, and second a medium negative potential and third the maximum negative potential. The three values of the potentials which, of course, are caused by a direct currentsource in the devices 19 are modified normally by the harmonics of the highest energy level harmonic, harmonics of a lower intermediate energy level and harmonics of negligible value. It should be stated here that the filter 69 is such that only the harmonics are transmitted to the devices l9 and the fundamental hundred cycle current is eliminated from these'devices and also that the ground connection at contacts of relay 99 when released causes the normal potential applied to conductor 99 to be such that both tubes H and T2 are actuated. Hence when as stated above, relay 99 is operated and the harmonics transmitted from the subscribers station when the non-linear element is not shunted by either of the circuits through the brushes 9 or H), these harmonics are of the highest energy level. Thus devices 19 will change its positive potential to become of a maximum negative potential so that both tubes will become inactive or extinguished whereas if the harmonics of a lower intermediate value are transmitted through the shunt circuit over brush I0 and due to the potentiometer ltll the potential will be changed to an intermediate negative potential so only tube H will remain active and tube 12 become inactive. However, when the ele ment 65 is completely shunted by the circuit over brush 9, the harmonics transmitted will not be of sufficient strength to materially change the positive potential on lead 98 and thus both tubes will again become active. These various conditions are brought about due to the travel of the brush 44 over the drums and thus as a result of these various potentials on conductor 98, the tubes will either be both inactive, that is, when On the other hand this non-linear elefull strength harmonics are ,transmitted' and tube H remain active when harmonics of a lower intermediate level are transmitted or both tubes will be active when practically no harmonics are transmitted. With this in mind, it is evident that combinations of'such various harmonics may be produced to compose digits so that before. the

, brush engages the first row of segments on any drum, both tubes will-become inactive and when the brush engages the succeeding four rows of segments on any drum either one or both tubes will become active, and when the brush engages the insulation between the rows of segments on any drum both tubes .will become inactive. As for example if. the digit JKL or 5, referring to Fig. 7, is the one that the brush M will engage, it is evident thatwhen the brush engages the first segment aconnection will .be established through brush it; when it engages the corresponding segment'in the second row, a circuit will be established through brush 9; when the brush A l engages the segment in the third row, a circuit will be completed through brush 9 and when the brush 44 engages the segment inthe fourth row a circuit will be completed through brush ill. Thus, for .the first segment in the first row only tubell will be active; for the second row both tubes will .be active; for the third row both tubes Will be active and for the fourth row only tube ill will be active, whereas when'the brush passes between these rows of segments, both of the tubes will become inactive.

With this in mind it is evident that the output circuit of the tubes H and '12 will when current flows through these circuits cause the operation of relays I62 and H33. As stated normally these output circuits are activeand consequently relays liiZ and 193 will be energized and when the full harmonics are first applied both tubes will become inactive. Consequently these two relays I62 and i513 will release. The release of these relays closes circuits for the two windings of the magnet "M which causes the brushes of the switches is to take one step. The next action will be that only tube 7| will remain active and relay 32 will release. This produces no effect. That is, the first register relay in group 15 will not be operated as there is no circuit closed through the brush and first contact of switch 13 to this relay. Then, both tubes will become inactive and relays I02 and H13 will be both released, causing the magnet M to energize the switches '53 to take a second step. Then both tubes will become active and relays IE2 and H33 will be operated. In this case the second register relay of the group i5 will operate over acircuit from battery, winding of this relay, the second contact and brush of switch 13 to ground at relay I03. Then both tubes will become inactive causing the switch to take a third step. Then both tubes will become active, causing relays m2 and H23 to be operated. The operation of relay I03 in this case closes a circuit for a third register relay over the brush and the third contact of switch 73. Then tubes H and 12 will become inactive causing the switch to take a fourth step. Then tube H only remains active and at this time no register relay will be actuated as there will be no circuit to this relay through the brush in the fourth contact of switch 13. Hence by sending this digit 5 the second and third register relays only will be operated. 'Iheseregister relays will lock in operated position by a ground applied at relay 8d. In the same manner seven other digits may be registeredby the settingof the other combination, ,as hereafter shown. It will be noted that in-this register there would be thirty-two relays, four relays for each digit and all been set in accordance with the eight digits suitable-apparatus will be provided whereby the settings of the register willbe employed for selecting connections beyond to the called subscribers line and when the register has performed its functions, the relay 8B will be released and the register relays restore to normaland also the relays 84, 90, 89, 87 and 88 and the register circuit itself will be removed from the connection leading to the first selector in any manner well known in the art. v 7

What is claimed is:

1. In a telephone system, a line, means for transmitting over said line groups of signals, each group representing a telephone digit and each signal comprising a number of harmonics of a fundamental frequency modified asto their energy levels to identify the digits, and means responsive to said groups of signals for recording the digits represented thereby. I

2. In a telephone system, a line, a source of alternating current connected to said line, means for producing harmonics of alternating current from said source at fixed energy levels, means for transmitting signals representative of telephone designations over said line comprising combinations of impulses of said harmonics at said fixed energy levels and at other modified energy levels, and means responsive to said combinations of impulses for making records representing corresponding telephone designations.

3. In a telephone system, a line, means for.

transmitting over said line groups of signals each group representing a telephone digit and each signal comprising a number of harmonics of a fundamental frequency modified as to their energy levels to identify the digits, thermionic tubes associated with said line operated in response to the succeeding signals in each group in corresponding combinations, and means responsive to current through said tube when operated to make a record representing a telephone digit as determined by said groups of signals.

4. In a telephone system, a line, a source of alternating current connected to said line, means vfor producing in said line. signals comprising harmonics of said alternating current, means for changing the energy levels of the harmonics in said signals from a normal level to two succeeding lower levels, means for combining signals of harmonics of these various energy levels into codes, each representative of a telephone designation, andmeans responsive to said combinations of signals for recording the corresponding telephone designations.

5. In a telephone system, a line, a source of alternating current connected to said line, means for producing in said line signals comprising harmonics of said alternating current, means for changing the ene gy levels of the harmonics in said signals from a normal level to two succeeding lower levels, means for combining signals of harmonics of these various energy levels into codes, each representative of a telephone desig nation, recording means, and, means for suppressing current from said alternating current source and for transmitting the code signals to said recordingmeans to record the telephone designations represented by them.

6. In a telephone system, a line andmeans for transmitting over said line groups of signals, each group representing a telephone digit and each signal comprising a number of harmonics of a fundamental frequency modified as to their energy levels to identify the digit, and a plurality of three-element thermionic tubes, means for transmitting said signals to the control'elements of said tubes, and means associated-With the cathode and anode elements of said tubes for controlling the discharges thereof to cause said tubes to discharge'at different potentials on their respective control elements as established thereon by said harmonics of difierent energy levels, and recording means responsive to discharges from said tubes to record said signals as digit designations. 1

7. In a telephone system, a line, a source of alternating current connected to said line, means for producing in said line signals comprising harmonics of said alternating current, means for changing the energy levels of the harmonics in said signals from a normal level to two succeeding lower levels, means for combining signals of harmonics of these various levels into codes, each representative of a telephone digit designation,

a plurality of three-element thermionic discharge devices, means for transmitting said codes in succession to the control elements of said devices and preventing current from said alternating current source from being transmitted to said control elements, and means associated with a cathode and anode elements of said devices for controlling the discharges thereof to cause said devices to discharge at different potentials on their respective control elements as established thereon by said harmonics of difierent energy levels, and means responsive to discharges from said devices for recording said codes as digit designations.

BENJAMIN F. LEWIS.

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