US1046952A

US1046952A - Automatic telephone system.

Info

Publication number: US1046952A
Application number: US53426709A
Authority: US
Inventors: Ernst Blos
Original assignee: Individual
Current assignee: Individual
Priority date: 1909-12-21
Filing date: 1909-12-21
Publication date: 1912-12-10
Anticipated expiration: 1929-12-10

Description

E. BLOS.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED DEC. 21, 1909.

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E. BLOS. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION r1221: DEO.21, 1909.

Patented Dec. 10, 1912.

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E. BLOS. AUTOMATIC TELEPHONE SYSTEM. APPLICATION TILED DEG.21, 1909.

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APPLIGATION FILED DEG.21, 1909.

Patented Dec. 10, 1912.

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AUTOMATIC TELEPHONE SYSTEM.

APPLIGATION FILED D130. 21, 1909.

Patented Dec. 10, 1912.-

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AUTOMATIG TELEPHONE SYSTEM.

APPLICATION FILED DBO. 21, 1909.

1 46,952, Patented Dec. 10, 1912.

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,5 ll i x I I I I I I I I ERNST BLOS, OF SCHijNEBERG, NEAR BERLIN, GERMANY.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Dec. 10, 1912.

Application filed December 21, 1909. Serial No. 534,267.

To all whom it may concern:

Be it known that I, ERNST BLos, a citizen of the German Empire, and resident of 10 Konigsweg, Schiineberg, near Berlin, Germany, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

The main advantages, as compared with existing systems, of the new system of aut0- matic telephony herinafter described, are first, that the number of current impulses necessary for making the connection desired is reduced to two per digit of the subscribers number; secondly, that only such of the contacts which are used to make the one individual connection, are subjected to Wear, and thirdly that the only movementof the selectors is a linear one over a maximum distance of one or two millimeters. None of the rotary or stepping movements which characterize the selectors of former systems are employed. In the well known Strowger system, the number of current impulses per digit reaches ten; the movement of the contact arms of the selectors is a stepping one over intermediate contacts which latter are not only useless for making the desired connection but are also subjected to useless. wear at each of the connections made. A further advantage of the selectors of the new system is that they can be actu ated directly by the line current, and that the adjustment of the preliminary selector which connects the calling subscriber to one of the first selectors which is not engaged is effected at one single stroke, and in the same manner the adjustment of each of the following selectors is effected. Therefore all connections are made within a very short time and in a very simple manner. Each of these advantages is obtained by the fact that the principle of selecting is not a quantitative one, as in the Strowger system, but a qualitative one, e. thedigits are not transmitted by means of a chosen number of current impulses of the same kind, but by a combination of impulses of different kinds, the number of impulses being the same in each case. The different character of the current impulses which are applicable to my system can be attained by varying their direction, or their intensity, or their frequency (in the case of currents of alternatiug or intermittent currents). or by sending impulses of the same character over difi'erl ent lines. A series of three difierent kinds of current impulses can be obtained for example by earthing a double line consisting of two-line wires L and L (1) earthing the line L, and not earthing L or (2) earthing the line L and not earthing L,,, or (3) earthing the lines L, and L, simultaneously. This isthe method of producing three difl erent current impulses which wil be used in the following description of my improved'automatic exchange system. The number of different current impulses available being three, it is necessary to use two-impulses of such kind so as to transmit each digit. In this way I obtain a total number of nine different combinations of impulses. This is suflicient for transmitting nine of the ten digits of the decimal scale; when numbering the subscribers therefore, one of the ten digits must be dispensed with, for instance, the Zero. and all of the numbers containing the cipher 0 must also be omitted.

The improved automatic selectors consist substantially of a series of toothed disks which. by means of small electromagnets, are moved through a very small angle, and around Which disks a series of flat tongues, parallel to the axis of the disks. are arranged. If pressed against the disks, only one of these tongues, corresponding to the relative position of the disks, can fall into ,the grooves of the disks and close the desired circuit.

I shall first generally describe the principle of selecting which I employ and then proceed to describe the arrangement of an exchange for 9 subscribers. The selectors of this exchange are divided. as usual, into the three general classes viz. (1) preliminary selectors, (2) first selectors. and (3) second or final selectors. The preliminary selectors connect the calling subscriber to a first selector which is not. engaged; the first selectors select the hundreds; and the second selectors select the tens and units of the called subscriber. The arrangement of the preliminary selectors is novel in that they are connected to the subscribers by means of single wires, the number of the selectors nevertheless being not greater than in the improved Strowger system. Beside the so lcctors mentioned there is a further single selector interconnected between the first and second selectors. This single selector which is called a central selector, transmits the combination of current impulses corresponding to the nearest free second selector within the calling hundreds to the calling first selector.

The principle of selecting employed will be understood from Figures 1 to 5, Figs. 1 to 3 whereof relate to the manner of transmitting digits and Figs. 4 and 5 to the manner of selecting a disengaged first or second selector. Figs. 6 and 7 show the arrangement of the combinations and the teeth on the selector disks. Figs. 8 and 9 show the construction of one of the first and second selectors, Fig. 8 is a section on the line XX of Fig. 9, Figs. 10 and 11 that of the central selector, and Figs. 12 and 13 some details of the preliminary selectors.

Figs. 14 to 18 are diagrams of the connections for an exchange having 9 :729 subscribers.

The principle of scZecting.If a number (say 2) of different signs is available, and 1 each variation is composed of n terms, the whole possible number of variations is 2. For instance, we can form, by means of the signs 0 and m, if each variation is to be composed of two terms, the following four variations:

(1) o o (2) o w w u (4) a: m

Now let us imagine two line wires, L and L in each of which may exist one of the current conditions. (1) o no current flowing through the line wire. 2) Q3 21 current of any kind flowing through the line wire. Then- Variation l no-current in both line wires.

2::current in line I. only.

3:0urrent in line 1J3. only.

4mnent in both line wires.

1. 0 w o a; 2. o a: a: 0 3. 0 w w a; 4. m o o m 5. a: o w 0 6. a: 0 m a: 7. w w o a: 8. w m w 0 9. w m m m La b L1 L1.

Each of these 9 variations consists of 4 terms, and is also to be transmitted over the two lines L and L,,. This is done, for

example, in the case of the variation 1 by sending two successive current. impulses through the line L in the case of variation (3 by first sending an impluse through L and then an impulse simultaneously through both L and L,,. In the case of variation 9 it would be etlected by first sending an imjulse simultaneously through both L and L and then repeating this operation. An example showing practical application of this principle is shown in Figs. 2 and 3. Fig. 2 illustrates four bars (1) each of which is provided with 9 grooves (2 and 3) and corresponds to one of the four vertical columns of Fig.

1. Across the bars nine tongues (No. 19), are arranged. The grooves of the bars may take up two possible positions relatively to the tongues 1-9. The grooves 2 are arranged precisely below the tongues, but the g5 grooves 3 are displaced upward by a distance :0 from the center of the tongues. The arrangement of these grooves is arrived at by substituting for 0 in Fig. 1 a groove which lies below the tongue, and for m a groove which lies at a distance a: from the tongue. Considering now the tongue 1, it may be caused to fall into the grooves on the parallel bars by displacing the bars II and IV downward through a distance a:

from the position illustrated. By this displacement of the bars all the other 8 tongues are prevented from falling in: the tongues 2 and 3 by the bar III and the tongues 4 to 9 by bar I; In this way each tongue corresponds to a certain combination of the bars displaced, and in all cases only that tongue, and none of the others, n fall in, whose predetermined combination is produced.

From this it is clear that by displacing one or more of the bars, a proper and accurate selection of any of the tongues may be effected. Fig. 3 is a diagram of connections of the electrical circuit for selecting the tongues over the two lines L and L The current flow state of the wires L and L is in this example effected by earthing the line of the battery B. Magnets 1a,, m m and )ILW are arranged in the battery line behind the arm of a switch in such a manner that the magnets m and m are connected to the lines L and L and after the first current impulse has been passed over the line, the magnets m and m are connected to the lines L and L,. The progressive movement of the ratchet mechanism is effected by the magnet m which is energized each time either or both of the lines L and L is or are earthed. The magnets m to m operate the IV respectively. For selecting the tongue 1 for instance, a movable earthed contact is moved over the row 1 in Fig. 3. When the contacts of this row are earthed by the movable earthed contact the magnet m is ener- 13a diagrammatically the 75 slotted bars F to tyt gized over the line L and thereby the bar II is moved through the distance .7. In addition the magnet m energized and the arm of the ratchet is moved right over the terminals ot' the magnets III and IV. \Vhen now the lower contact of the row 1 in Fig. 3 is carthed through the moving contact, the mag et m is energized and the bar 1 of Fg. 2 moved downward through the distao (1 that the tongue 1 now falls into the grooves of the parallel bars. Simultan'eously the magnet 11/ is energized and the arm of the step-hy stcp switch is moved 'hrouglt another step. It will he understood from the foregoing description that only the tongue 1 falls into the grooves of the bars. It is of course neces ary that the bars be retained in the positions to which they have been moved by the magnets. The means proposed for etfecting this will be described later as tll 0 shall the means used for re urning the step-by-step switch arm into its initial position.

In Fig. 1 the arrangement of the grooves or teeth on the bars is substantially the same as in Fig. 2-the edges of the bars pressed against the tongues being inclined in order to obtain automatic return of the bars. This arrmigement is applied at the central selcctor and will he specially described when describing the central station arrangement.

The variations according to Fig. 1 may be transmitted simultaneously instead of in two parts over two wires it' 4 wires L,, L L L as shown in Fi 5 are provided. Each wire is then connected to one of the four magnets m, to m and the step-by-step mechanism is entirely dispensed with. For example to select tongue No. b, the threefold switch No. (3 is pressed downward whereby the lines L L L, are carthed, the magnets mm and m cncrgized and the rods I, III and IV moved. As can be seen from Fig. 2. only the tongue 6 can fall into the grooves of the bars. This momentary transmission of the 9 variations of current is employed on the prel 'ninary, first and auxiliary selectors. In the case of the preliminary selector however the variations 0 0. 0 0 must he provided and therefore the four bars must he provided with holes or grooves arranged directly under or opposite a tenth tongue. This tenth tongue will of course be normally in the grooves and as soon as one or other of the bars is moved the tenth tongue will he raised out. of the grooves and suitable contacts are thereby operated.

The table of comltina ions or 'ariations given in Fig. 6 is derived from that given in Fig. 1. by writing each of the variations in that figure nine times to form 9 groupsthereby forming the rows I to IV. in Fig. 6. The rows V to VIII are formed by using th 9 variations of Fig 1 successively in each group in Fig. 6. The toothed or grooved bars, see Fig. 7, and the corresponding tongues are disposed relatively to one another in the manner corresponding to the table in Fig. 6 and as explained with reference to Fig. 2. In the position of eaclro there is a groove under the tongue and in place of each a the groove is at a distance a from the tongue. In order to simplify the arrangement of the grooves the distance a: is made equal, in Fig. 7, to half the pitch of the tongues. Further, for reasons hereinafter explained, the space between each group of nine is greater than the pitch of the tongues in each group. To test the correctness of this arrangement let us follow the selection of the tongue 99. According to the table in Fig. 6, all the bars have to be moved in order to allow the tongue to fall into the grooves-see Fig. 7at the foot. ()11 the other hand all the other tongues must remain out of their grooves. The tongues 11-39 are held out by the bar I, 4169 by bar II, 71-79 by the bar III, 81-89 by the bar IV, 91-93 by the bar V, 94-96 by the bar VI, 97 by the bar VII and 98 by the bar VIII.

I shall now proceed to describe a selector which may be taken as representative of all the selectors which are required, with the exception of the central and preliminary selectors. In Figs. 8 and 9 a second selector is illustrated by way of example, Fig. 8 being an elevation and Fig. 9 a plan. In the first place, imagine the teeth and grooves of Fig. 7 as arranged on the peripheries of disks, which may be rotated through a small angle equal to half the pitch of the tongues. In Fig. 8 there are eight disks 4 which are loosely rotatable on disks 5 and these latter disks are arranged side by side, on a member 6 and pressed together by a closing disk 7. The disks 4 are controlled by magnets 7m, m m to m which are all fixed to a plate 8. The magnet m for example, controls the bottom disk 4 in Fig. 8 by means of its right angled armature 9 which engages in a. groove on the disk. In order to retain the disk in its position of rest or working position, as the case may be. a flat. spring 11 is arranged for each disk and is mounted on a pin 10. The flat springs 11 are adapted to engage in one or other of two notches on the'disks, corresponding respectively to the position of rest and the working position. The magnet m serves to return the disks into their position of rest. its bell-crank armature 9* engaging in a notch in every one of the disks 4, as seen in Fig. 8. The tongues 12, supported opposite the grooves on the peripheries of the disks are held with their ends working in grooves on the bed plate of a magnet M, and are all pressed against the disks 4 when the magnet M is energized. Each tongue is pro vided at its upper end with a part 13, which carries the contacts 14 and presses them,

when the tongue drops into the grooves on the disks, against the contact ring 16 which is cast in the insulating ring 15. The insulating ring 15 is itself fixed to a plate 17 which is fastcwd to the supporting body 6 for the disks. The contacts 11 are also cast into an insulating ring 11 which is fastened to the bed plate of the magnet M.

As mentioned above, the second selector just described is also typical for first selec tors. The central selector is constructed somewhat differently and will be understood from the following description of Figs. 10 and 11. The preliminary selector is constructed somewhat similarly to the central selector but has some modifications which are, illustrated in ligs. 12 and 13. In the central selector it is necessary that the tongue to be selected fallssimultaneously with the motion of the bar 18 and that it has closed its electric circuit at the time when the bar completes its motion. To this end'the tongues 19 are, under the action of springs 20 (Fig. 11) continually pressed against the bars 18. The bars 18 are longitudinally slidablc in guides 21. The sliding motion of the bars is produced by ma gnets m -m and when these become deenergized the bars 18 are returned to their positions of rest by springs 22. In order to facilitate as much as possible, the return movement of the bars, the teeth on which the tongues bear in the position of rest are inclined with a slow inclination as described above with reference to Fig. 4. In the case of a preliminary selector, it is not necessary that the bars be immediately returned but the bars must remain in the position to which they have been moved, until the subscriber returns the preliminary selector back to the disengagcd position at the end of the conversation. Each bar is therefore held in its drawn out position by means of a pawl 23 (Figs. 12 and 13) which engages in a special groove 24 on the bar. This pawl remains in engagement until all the pawls in engagement are withdrawn by means of a right angled armature 25 on the magnet M (Figs. 12 and 13).

The principle of selection employed has now been described withreference to Figs. 1 to? and suitable selectors for the various purposes have also been briefly described. I shall now proceed to describe the arrangement of a station having 9 (i. e. 729) subscribers.

Exchange for 9 subscribers. At this statici only the digits 1 to 9 are employed for nun' rering the subscribers -the cipher 0 must be omitted for the reasons given at the beginning of this specification. Further only numbers each comprising 3 digits are employed. The numeration therefore commences with 111 so that it is unnecessary to precede units or tens with a corresponding number of naughts as is necessary in other systems.

The subscribers are numbered--111119, 121-129 and so on to 191-199; 211219, 221 229. and so on to 291299; 311l9, 321329 and so on to 239L399. and so on until 911- 919. to 991%)99 all numbers between 111 and 999 and containing the cipher 0 being omitted. -\s in other systems. the subscribers are divided into groups but whereas each group in other systems embraces 100 I divide them into groups of 81. so that in the present instance there are 9 groups. The first group embraces the numbers 111499; the second group the numbers 211299 and so on till the ninth group embraces the numbers 911999. For each group of subscribers there must be provided as many first and second selectors as the maximum 11- mated number of simultaneous conversations. In the present instance 9 simultaneous conversations are estimated and provided for in each group which is about 11 per cent. and usually sutlices. Each group of subscribers are given nine first selectors which are made available to each subscriber by a ninefold contact on the preliminary selector. In addition to the nine-fold contact av tenth is provided for each subscriber, as above mentioned, to act as a switch. Each subscriber is permanently connected to this switch and is automatically connected by lifting his receiver to one of the nine first'sclectors over the nine-fold contact. As usual a preliminary selector is provided for each subscriber, which preliminary selector is provided with the nine-fold contact and the return contact.

In Fig. 14 there is illustrated a preliminary selector to which it shall be assumed that subscriber No. 124 is connected. The multiple or manifold contactsf to f are connected to the trunk lines a, I), 0 to a. b 0,. These trunk lines have branch connections to all the nine-fold contacts of the 81 preliminary selectors for one group of subscribers, only the zero or naught contacts being omitted-for example f is omitted. From the trunk lines (L -(5., and Z ,b.. lines branch off to nine first selectors, the first of which is illustrated diagrammatically in Fig. 16. The lines 0, to c, are connected to the relays 13-11 of Fig. 15 which are all connected to the positive pole of the battery B. These relays close a set of contacts arranged in series and from which four lines lead over the switch a, to the four magnets m to m In the position of rest the contacts from r, connect up all four magnets m; to 111-w to the negative battery pole over the lines 26, 27 and 28. In the working positions these contacts connect the magnets m m to the contacts from 1' These last mentioned contacts when in their position of rest connect the magnets m m and m to the negative pole B, and when in their working position they connect the lines leading to all four magnets to the contacts of 1 and so on in the same way throughout the group, the contacts of each relay in turn close the magnet circuits, when in their position of rest, in the same order as the letters as in the table of variations given in Fig. 1. In the working position the contacts of any one relay always con nect up the contacts of the next following relay to the lines leading to the magnets. The lines leading to the switch 8 also branch ott' to the switches of the other 80 preliminary selectors of the same group of subscribers so that the magnets m to mv of the subscriber in question are connected to the contacts of the relay 23, the switch 8, of which will be just closcd'by the relay r of the calling subscriber. As this closure of the circuits is only a momentary one, it is practically impossible that the switch 8 be l closed simultaneously by two selectors and that thereby two subscribers are connected to the same first selector. Care must now be taken that r, is immediately switched over on to the contacts of 1, after magnets m to m are energized. This takes place, as described later, as soon as that tongue at the preliminary selector which corresponds to the first selector selected, falls into the grooves in the bars. The double line leads from the subscriber's station to two current rails'a and b A third rail is connected over the magnet winding of m and the line 28 to the negative pole of B. The lines a and Z), form the speaking circuit and the line c forms the blocking circuit. The lines a and 6, are also connected to the contacts 29 and 30 against which springs 31 and 32 rest. From these the lines a and 5 lead to the second selector which has the connections Nos. 111-199. A branch from the line 6 leads past the spring 32 to the relay 1' which is also connected over the line 33 to the positive pole +13. The negative pole of B is earthed. \Vhen therefore the subscriber presses down the key 12 i on the right the following current impulse is transmitted: positive ole of B, 33, r spring 32, contact 30, righthand 124 key of the station, earthed to negative pole of battery. The relay r closes switch 8 If now all the first selectors of the calling subscribers group are disengaged, that is to say the relays r, to 1', are not excited, then current passes from the positive pole of B and line 26 only over the contacts which are at rest, the s rings of the relay r magnets m,m v and ines 27 and 28 to the negative pole of The four magnets move their corresponding bars so that, according to Fig. 4, the tongue No. 9 can fall into its grooves.

J In this way both lines of subscriber No. 124 are connected to the lines of the first selector (Fig. 16) over the lines a and b the two upper springs f and the trunks .a and 1),. Since the under spring f bears I on the line c the following circuit will be closed :-+B, 26, 1' 0 under spring f c m 28 and -I. The relay 1', is vthereby energized and its springs switch over the lines for s, to the contact springs r In this way the first selector of the subscribers group is in the engaged position and the next calling subscriber from the same group will be connected up through the contacts of r to the second first sef lector. In the circuit of the relay 1*, there i is also arranged the magnet m wh ch has to be cut out by the contacts of the prelimii nary selector at the end of the conversation. f It must therefore be so dimensioned that it I reu ains inoperative when in series with '13. It is rendered operative as described later bv short circuiting 1' The purpose of the contacts 29, 30 and 34 remains yet to be explained. While the contacts 29 and 30 break circuit when the bars are moved, the contact 34 makes circuit. I The former, 29 and 30, prevent the calling I subscriber from being called up and and the current impulses now about to be transmitted have no more influence on the pre liminary selector. The latter, 34, closes the l blocking line c over 35, 34, 27, 28 to the negative battery pole and the subscriber ht is engaged for all other calling subscribers. The action of this connection will be explained more fully later. The calling 'subscriber is therefore connected momentarily to the first selector Fig. 16 by once carthiug his 0 line and may now get on to the desired number by 6 further current iml pulses. Assume now that No. 124 wishes to call up No. 419. He must first pass his earthed contact over the row 4 in Fig. 3 whereby two current impulses are trans-- mittcd to the first selector. The first impulse is over line L, and energizes M, the second over line L, and energizes M. IV of the first selector. The switching over is effected by ratchet mechanism, the arm of which rests on the

contacts

36 and 3 7 in the pcsition of rest of the selector. This ratchet mechanism consists of a disk 100, partially toothed, havin two projecting parts 101 and 102 and being held under pressure by a spring 103. The disk is held in position by a ratchet 104 which fits into the teeth of the disk and which can be attracted by the magnet m being its armature. The hook 105.

which is linked to the armature 41 of the forwarding magnet m is also pressed against the toothed circumference of the disk by means of the spring 106. When the armature 41 is attracted by the magnet m itslinked hook 105 gets into the next higher tooth, pawl 104 meanwhile securing the position of the disk. If, now, m is demagnetized, its armature 41 is returned by the spring 107, whereby the disk is turned and the contactpieces of the arm 101 reach the

contacts

42, 43 and 44. The same action is repeated on occurring of the next current impulse energizing m after which the arm 101 covers the

contacts

58 and 59. The arm is restored into its rest position by energizing the magnet m the latter attracting its pawl-armature 104 and thereby simultanemisly retracting both pawl 104 and hook 105 irom the teeth of the disk, whereby the disk is allowed to follow the traction of the spring 103.

The full circuits are as follows: (1) L earthed; B, line 38, m 39, m (1 upper spring f a left hand key 124 l, earth to negative pole of B. The rotation of one of the disks through a small angle is effected by 912 as also is the closing of can... at). The magnet m; attracts its armature 41 and thereby moves the switch arm 36 to the

contacts

42, 43, 44. (2) L, is earthed, +B, 38, m 39, m 43 switch arm 37, by, 1),, center spring f b right hand key 124 of the station, then earthed to negative pole of B.

he magnet m rotates its disk and closes its contact 45 which remains closed like Contact 40, because the armatures of the operating magnets remain in their attracted position during the entire duration of the conversation. The attraction of the armature 41 by we; also closes the following circuit: +13, 38, 46, 47, 48, 44, T1,, 49, 50, and the negative pole of 13. h r,,, consequently closes an 8 pole switch to the left of r in Fig. 16. In this way the magnet m and the magnet m of the central selector (Fig. 17) are energized by the closure of the fol lowing circuit :-+B, 51, on the one hand m (Fig. 17) 52, 53 and 40 on the other hand m (Fig. 17) 54, 55, 45 and then together over 49, 50 to the negative pole of the tery B. Both current impulses of the digit 4 are therefore transmitted to the central selector. The magnets m and m of this selector move their bars whereby the multiple contacts Z, descend and if none'of the second selectors of the fourth hundred are engaged, the combination of the first second selector will be transmitted over the contacts 1;, at the left hand side of Fig. 17 to th magnets m and m of the first selector (Fig. 16). In detail the principle and working of the groups of relays 1' to 1' is precisely the same as in the group of relays 1", to r, of Fig. 15. The circuit for this is as follows :l-B, 56, 57, contact springs of 1" multiple contacts 2,, m and

m

49, 59 to B. It is assumed here that the impulse which energizes 7' lasts somewhat longer than the time required for shifting the bars of the central se' ct r.

for the magnets WWII and m This may be effected at the sending station by a suitable arrangement. \Vhen the earthing of the line Lb (Fig. 14) ceases the armature 41 (Fig. 16) moves the switch arm farther on to the

contacts

58 and 59. In this position the exciting circuit of the main magnet M of the first selector by means of the metal piece 60 of the switch arm is closed over 38, 58, 59 and 50 and thereby all of the tongues of the selector are attracted but only the tongue 41 is drawn into the grooves of the bars and the multiple contact 9 at the top lefthand of Fig. 16 pressed against the contact rails 0 b and In thisway the subscriber is connected to the switching mechanism of the second selector (Fig. 18) over the upper springs 9 lines ag and by As the third spring g rests on the rails cg, the relay 1' is also energized over lines 56, cg bottom spring g cg, 61 and through the winding of 1, The relay 1", when in series with 7",, remains inoperative. The relay 1' by switching its spring, will cause the next caller for a number in the fourth hundred to be switched on at the calling first selector to the No. 2 second selector of the four hundred group.

The transmission of the digits 1 and 9 is effected by passing the earthed contact over the rows 1 and 9 (Fig. 3) successively whereby L is twice earthed and then L and L together are earthed. In the first earthing of L current passes from +B over 62, 1a,, 63, m 64, by center contact arm 9 bg, center contact arm f b L right hand key 124, then earthed to -B and causes the movement of the disk corresponding to m and also the movement of the switch arm in Fig. 18 to the contacts 65 and 66. This is repeated for the magnet m whereupon the arm covers the contacts 67 and 68. The earthing of the lines L and L now follows for the selection of the digit 9. The earthing of the latter follows the circuit path just described but passes over the magnet m and contact 68. The earthing of L takes place over m 67, ag upper contact arm 9 ag, upper spring f a left hand key 1241 to the earth and The earthing of these two lines therefore effects the movement of the disks corres coding to magnets m and m an the switch arm is moved forward to cover the contacts 69 and 70. The same is repeated After completion of this latter earthing the switch arm of Fig. 18 has moved into its end position and closes in the first place the circuit for M, by means of the contact piece 71 over 62, 7 2,73, 74. Further in this end position the lines cg and by are connected up to the central battery B over 75, 76, 77, 78. From the central battery B there lead

lines

79 and 80 to the rails a and b so that the speaking circuit to the subscriber is completed through (1 and b the two upper springs Z lines a and Z1 contacts 81 and 82,'and rails a and b The blocking line c of the subscriber is arranged over the lower contact arm l of the second selector rail 0,, switch, contact 83, line 74 to the negative pole B.

The relays 1' and r (see below and above the central battery Fig. 18) operate the sounding device 84. As long as the re ceiver of the calling subscriber remains on its hook and the alarm is in the line circuit, the calling relay 7",, does not operate. Only when the receiver is lifted and the microphone is switched incircuitin place of the alarm does the relay v3 attract its armature. This relay then closes its contact 85 whereby a calling current is transmitted over this closed contact and the stationary contact of 1' to the line of the called subscriber. In this way the called subscribers alarm is operated. At the same time the calling subscriber hears a humming sound in his receiver which stops as soon as the called subscriber takes his receiver from the book as the relay 7' then attracts its armature and cuts out the sounder. This method of switching in the calling current is however not new.

\Vhen the conversation is ended, the operated selectors must be returned into their positions of rest. This is effected by the calling subscriber earthing his line L... Since this line is still connected to 77 over contact 75, the relay 1* is energized when the line L is earthed. By closing the contact 86 of the relay 73 the magnet m is also energized and this magnet releases the switch arm so that it returns into its initial posit-ion and thereby M is cut out. In consequence of the energy stored in the arm due to its motion the arm passes over its position of rest and causes contact for a brief period between the

spring arms

87 and 88 whereby the magnet m", returns the disks of the second selector to their starting position. The relay 1",, also closes the contact 89 and thereby short circuits the relay r (Fig. 17) of the central selector, as this relay is on one hand connected through 56 to the positive pole of B and on the other hand to the branching'point 90, which is further connected directly to +B through line 91 and contact 89. This short circuit does not only denergize the relay 1",, and thereby cause its contacts to resume their positions of rest and bring the second selector into disengaged position but also energizes the relay T of the first selector (see the lowest part of Fig. 16) direct over contact 89 from 1",, ofthe second selector, line 91 Cg and Cg and thereby closes both the contacts of this relay. The result of this is in the first place the energization of m over line '92, contact 93 and line 50 whereby the switch of the first selector is released and consequently Mg de e'ne-rgized. The switch arm of the first selector closes the contact 94 in the same way as described with reference to the sec- 0nd selector, and thereby energizes 'the re turn magnet m which brings the disks hack into their position of rest. As in the case of the second selector, the contact 94 is only closed momentarily, owing to the hinet ic energy of the switch arm on returning carrying it past its position of rest and after this closure of the contact 94 the switch arm sets back into its proper position of rest over the

contacts

36 and 37. The contact 95 is also closed by the relay 1 whereby r, F ig. 15) is short circuited. 1', is connected by means of line 26 between the positive pole of the battery and the branching point 96 which is now connected directly to +B over contact 95 and line 92. By this short circuit the relay 1', is deenergized, its contacts return to their positions of rest and the first selector is thereby brought into the disengaged position. The short circuit further causes m of the preliminary selector to attract its armature and the multiple contacts f and f, to break circuit. The path of the current is as follows: +B, line 92,

contact

95, 96, 0,, bottom arm of f 0 m line 28 -13. \Vith this return of the multiple springs f and f the selectors required for the conversation are all returned to their disengaged positions and are ready to be used for a new call.

\Ve have still to consider the case in which the called subscriber is engaged, having been called up, let us assume, by another party. In this case the multiple cont-acts No. 1 (Fig. 18) on another second selector for the numbers 411 199 already rest on the contact rails a 7),, and c of this other selector and its ratchet mechanism is in its end position corresponding to the

contacts

75, 76 and 83 of Fig. 18. Its rail 0, is therefore connected through the switch arm to B (in Fig. 18 through contact 83 and line 74). Of course all the multiple contacts bearing similar numbers are connected in multiple. When now, the switch arm of the selector operated by our call, passes into the end position on the occurrence of the four current impulses which correspond to the digit9, it touches, in passing, the contact 97 By means of this contact, should the called subscriber be engaged, the following circuit is closed: +B, 1* line 77,. contact 97, contact arm, rail 0 bottom arm of Z the same arm on the second selector over which the subscriber is already called, the rail 0, of this selector switch arm, contact 83, line 74 to .B. This current impulse energizes 7' whereby all the selectors called into action by our calling up the engaged subscriber are returned to rest in exactly the same way as when the line was earthed by the calling subscriber at the end. ofthe conversation. If the called subscriber 419 is himself lling up sonie othersubscriber the M118 i r im n nt: lector arebroken'a l contact 98 is closed, I connected to (exactly as described contact and lines hent-herefore the switch arm a 191 uefou w V i n 19,194) i I h s :way .215 s dxall h select B Dive se gindi. with 6 27 and28) rs called are returned as described .i b y the pi 'tiqular natiii'e o th co thejcallingfcuu rent. 'nt calling subse 1 hook tl is re ei ve r from the This sounds the rves t the linecalled i s-engaged ntjt'hat tlie system described lic able to station s y'ithfifl il and more sixbscrlb The ini berlof selectors employed has 'nierely to be increased by a second "sel select tlie tt a first selectoi increased cllidiilg ,e ali n o f.,: simulta he number q f' .prelimi a1 'ith 9" subscriber two caters I claim I 1. An utoma'tic teleplione selecting system ei'n flo ing'difler nt' 'nibinationsof no currentl sequent ncrement of one or ZIDQIQJO ,"grooved menib e U l spending tov said ombinat ion is enabled te v I fall into :theugroov es onqthe ggr ooye xy em-i m w tongues remain criber is 1 11- i.

h l r beinotitied.

' that when the.

n circuit bridged s' a signal to;

w {arm areas-t brought axiall l initial positions ,1-(mi d, 1: U =1 g 3. selector for an.automatictelephoneuOS- selecting systemofthetype described; com

, magnets, meansdoperated by said magnetsv .7

for nioying said disks in desired; combine-e; Y

tions, each combination being arranged to 115 7 bring only one semi the gr ooveson a,ll:the.

; disks axially in line contact carrying; nst a oppositethegroove-s when br0ught;a-x' ially of the grooved disks. 1

amt-s "and ieui'r e nt impulses for disa ,t; u \,.-u tingu sh ng the various subscribers comto the number of different ciphers used todistinguish thesubscribers, means for send ing current .thro i gh tlie contacts 0 id rows desired, selectorsilocated ataiigcsn tral station, magnets on saidfielectcrs, (lit-J ferent magnets or eombinationiof{inagnetg being energized when current is sent. through the contacts of different rows-,emovi able grooved members corresponding to said magnets and operable by the same, tongues placed yariously over the grooved and nongrooved partslof said men'iber, said ltongues zu'a t0 9 Q$P ;t-Qfl fixe combination at impulses; so thaton tlieko currence of said conlbina tiontandflthe; com-: I

ily th ngue:

bers \yhile the reinaini out of the grow-es. I a a t-, a 1

S QL o 1 autoniat selecting system of the type-describedcom prising a plurality oI d sksiiiionntedparallel to one, :Lliuilltlbfllld rotatable:

v r qghz alsosmall angle, notches on theiper1pheries-.-of;

Said dis s, said notches beingw axially in line and axially displacedtothe notches ofjadjacent disks in a predetermined manner-,-

electro-niagnets means operated by saida'95 magnetsfor moving said diskssintdes ed con binationspeach. eonibination being a ranged to b'ring only one se t oiieigrhwu n al the disks, axially in'line Contact ca the, grooy heninto said gro and means for U prisingva plurality of disks .mountedgparalle to one another and rotatable through a smalln angle, notches on the peripherieseof gaid disks, said notches beingiaxially inlineaanddlO aniall'y displaced to tlie notches of adjacent;

disks" inaagpredetermined. inanneiz i'eleetro in line and adapted to falliinto a e i n-line to effect-selection, a magnet adapted 12.0 to draw said armsagainsfithe peripherie disks, said notches being axially in -lin eaand axially displaced to thenotehes of adjacent,- disksin a predetermined manner -electr -LBO magnets, means operated by said ma nets for moving said disks in desired com inations, each combination being arranged to bring only one set of the grooves on all the disks axially in line, means for retaining the disks in the positions to which they are moved by the magnets.

5. In an automatic telephone enchango of the type described, preliminary :sel first selectors, means for automatically" con necting the preliminary selectors tg a disenga of re ays operable from the preliminary selector, multiple contact arms operated by said relays so that when the firstfrelay is operated by the preliminary selector -it automatically cuts out the first selector of the set of first selectors and connects the next caller to the second relay of the set and second selector of the set of first selectors and so on through the set.

6. In an automatic telephone system of the type described, a selector, means for sending combinations of current impulses to said selector, magnets in said selector adapted to be energized in combinations corresponding to the combinations of current impulses sent, means operated by the diflerent combinations of energized magnets for effecting selection, a switch arm at said selector, means for moving said switch arm stepwise once after each combination of impulses,

' and means for returning said switch arm when desired.

7. In an automatic telephone system of the type described, a selector, means for sending combinations of current impulses to said selector, magnets in said selector adapted to be energized in combinations corresponding to the combinations of current impulses sent, means operated by the difierent combinations of energized magnets for effecting selection, a switch arm at said selector, means for moving said switch arm stepwise once after each combination of impulses, means for returning said switch arm, when desired and means rendered operative by said switch arm when returned for efiecting the return of the selecting means to their initial positions.

8. In an automatic telephone stem of the type described, sets of first se ectors, prehminary selectors for selecting a disengaged first selector of the desired set, means for copies at um patent my be mama ed first selector, comprising a group,v

tem comprising the subscribers station for sending comsending combinations of current impulses to the first selector selected by the preliminary selector, sets of second selectors for said first selectors a relay (r rendered operative by'sending a combination of current impulses to the first selector, for establishing communication between vthe second selector and the first selector, and means in- .terposed between the first and second selectorffor connecting said first selector to a disengaged member of the set of second selectors. 9. An automatic telephone selecting sysa sending device located at binations of current impulses, diflerent combinations being arranged to correspond to difierent digitsused for numbering the subscribers, magnets located at the central station and arranged to be energized in different combinations corresponding to the combinations of impulses transmitted from the calling. station, controlling members moved by said magnets when energized, and means rendered operative only by the movement of a particular combination of said controlling members for connecting one subscriber to another.

' 10. An automatic telephone exchange system comprising a sender, located at the subscribers station, for sending nine different combinations of current impulses and comprising 9 rows of contacts corresponding one to each combination, magnets located at a central station and equal in number to the number of terms in the combinations required for selection of any given subscriber, a number of movable members controlled one by each of said magnets and a plurality of contacts to be selected said contacts cooperating with the movable members in such a,!nanner that when a particular combination of the movable members is moved onl that one of said contacts is operated which corresponds to the combinations of current impulses which operated the movable memers.

In witness whereof I have hereunto set my hand in the prwence of two witnesses.

' ERNSTBLOS. Witnesses:

Wowmun Ham-T, HENRY Hnsrnn.

Washington, D? 0; a