US860902A - Telephone-exchange system. - Google Patents

Description

PATENTED JULY -23, 1907.

3. E. CLEMENT. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV. 11,1905.

' 2 SHEETSSHEET 1.

PATENTED JULY 23, 1907.

E. E. CLEMENT.

. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV. 11,1905.

2 SHEETS-SHEET 2.

F11 mam 3] wow 14 012 EDWARD E. CLEMENT, OF WASHINGTON, DISTRICT OF COLUMBIA.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented July 23, 1907.

Application filedllovemher 11. 1905. Serial No. 236.889.

To all whom it may concern:

Be it known that I, EDWARD E. CLEMENT, a citizen of the United States, residing at Washington, in the District of Columbia, have invented a certain new and useful Improvement in Telephone-Exchange Systems, of which the following is a specification, reference being had therein to the accompanying drawings.

My invention relates to telephone exchange systems, and has for its object the improvement of such systems in general, and of common battery systems in particular.

Briefly stated, the invention comprises a system in which tlie normal supply for signaling over lines is fur nished by a secondary battery, which maintains a constant potential across the central office ends of all the lines. Connection terminals are provided in open multiples of the line, and signal devices are included therein between the connection terminals and the battery. The operators cordcircuits are all bridged on to the main generator, through impedance coils, the direction of forces in the generator being such that when a connection is made with a line, like poles of the generator will be opposed to like poles of the secondary battery, whereby a balance of potentials is produced on the linesignal, and the battery is kept constantly charged. Since the battery is floated across the terminals of the generator during all conversations, the inequalities in electromotive force due to the commuting of the generator current, are smoothed out and do notinterfere with conversation.

My invention is illustrated in the accompanying drawings, in which Figure 1 is a diagram of a central station and two subscribers stations. Fig. 2 is a diagram of a modification.

In Fig. 1 of the drawings, XY are the two subscribers stations, and W is the central oflice. I have shown at each subscribers station the usual transmitter T, receiver 1t, switch-hook and ringer, and instead of a condenser in series with each ringer I have shown a coherer, in accordance with the design set forth in my Patents, 719,998 and 719,999v

At station X the transmitter is connected directly to the line-wire 2 through the branch 9, on one side, and on the other side through the primary '5 of the induction coil I and by wire 8 to the up-contact S of the switchhook S The secondary i of the induction coil is connected to the receiver R. The switch-hook is connected to the line-wire l, and the ringer Q is connected in a bridge 56-7 through the coherer G. This coherer as shown is a glass tube mounted and insulated from the switch-hook, with a filling of active material composed of a mixture of fine hard carbon or very hard steel filings or broken needles or the like.

At station Y, the transmitter and receiver are shown connected in series between the line-wire 3, through branch 10 to the contact s, the induction coil being omitted. A coherer C is employed in series with the ringer Q, in the bridge l314, but instead of being mounted on the switch-hook, this coherer is fixed and is adapted to be tapped by a hammer h actuated by a cam stud on the hook lever S when the latter rises. The coherer and ringer are cut off during conversation by the opening of the bridge 121314 at the contacts.

At the central office, the lines are provided with contacts J, J, each having a spring and sleeve j, j, bridged in open multiple. Pairs of plugs, P, P are employed for interconnecting lines, their tips p and sleeves p being connected respectively through the cord-conductors 1820 and 1719. A key K when actuated serves to connect ope-rators set 0 through the wires 2122 across the cord conductors 1718. A ringing key K when actuated, serves to separate the conductors 192O leading to the calling-plug P, from those, l718 leading to the answering-plug P, and to put them on the Wires 2324 leading to the ringing generator G. I preferably include a condenser Z in the circuit of this ringing generator, because of the added effect thereby produced upon the cohere'rs.

The cordconductors 17l8 are permanently bridged on the main generator G, which has an output ample for the entire exchange load at all times, in order to obviate any danger of overflow from the battery B.-

Between the generator and the cord-conductors I include the impedance coils g, which are preferably of very low ohmic resistance, but so wound and with magnetic circuits so designed, that each will have a very high coefiicient of self-induction. These coils serve the double purpose of choking out voice currents from the generator mains, and of smoothing out inequalities in the generator current conveyed to line. Asimilar function is performed. in each line by the coils L, L, the former of which is the coil of the line-signal.

The operation of the system shown in Fig. 1 is as follows: Normally there is no current flow in the lines, a though the battery B maintains a constant potential difference between the terminals. When a subscriber, as X, calls he takes down his receiver, the hook rises, and line-signal L is energized by the current flow from battery B. The operator inserts the answering-plug P, and thereby connects the generator G across the line through the conductor 1718, in parallel with the battery B. The signal L is thus exposed to equal potentials on both sides, and the fiow of current through it from the battery stops. It is to be observed that the battery B is kept charged to its point of highest efi"1- ciency all the time, because the instant its potential falls, and an operator is answering a call anywhere in the office, the generator G will be connected back to it, and will charge it to the maximum. The generator supplies current to the line for talking, but the battery is in parallel with it, and in conjunction with the coils g smooths out the inequalities. After ascertaining the number wanted, through manipulation of the key K, the operator inserts plug P, and actuates ringing key K in the usual way. The sharp alternations of current thus produced on the line 3- cause the coherer C to set, and itsresistance to drop from its normal point of 140,000 ohms or more to less than 100 ohms, whereupon the ringer Q will be eHiciently actuated. When the subscriber Y answers the tapper h is raised and falls upon the coherer to shake. apart its particles.

Fig. 2 is a diagram of a modified arrangement in which the magnets L and L are relays, and their associated magnets L and L may be relays, while the coils g already described are also the windings of relays which control the signals and are duplicated, the cord conductors being broken by condensers, so as to give double supervision in a well known manner.

The substation apparatus is the same as in Fig. 1 except that I have substituted condensers for the coherers in the ringer branches, this being a common and well known arrangement. Other changes can be made without departing from the invention.

Obviously, it the voltage of the battery B has fallen at any time, so that there is a back flow of charging current through the magnet L, the signal may remain actu ated unless special means are provided for its retirement. To avoid this liability I prefer to make the magnet L polarized, as indicated in Fig. 2 and in that event it is sure to be properly restored when a plug is inserted, for there is always sure to be a small fractional difference of potential between the generator and the battery terminals.

Having thus described my invention, what I claim is:

1. In a telephone system, a line circuit, a secondary battery supply, and controlling means for current in the circuit. a translating device between the controlling means and the battery, a charging generator, and means to conncct the same during conversation between the controlling means and the translating device, substantially as described.

2. In an electrical system, a line circuit, a secondary battery for supplying current thereto, a circuit closer, a connection terminal and means associated therewith to connect it with other circuits for transmission purposes, said terminal being located between the circuit closer and the signal device, and a charging generator adapted to be connected to said connection terminal by the act of connecting it with another circuit, substantially as described.

3. In a telephone exchange system, a subscribers metallic line circuit, a substation and switch, a storage battery and a line signal device with a permanent central oflice connection from the line through the signal device to the battery, a connection terminal for the line between the substation and the signal device, a coiiperating connective circuit for connecting the line with other circuits, and a charging generator bridged across the same so as to be brought into parallel with the storage battery. and to produce a balance of potential across the terminals of the signal device while the line circuit is connected, and to recharge the battery through the signal device at such time while maintaining the signal inoperative, substantially as described.

4. In a telephone exchange system, a storage battery, a plurality of subscribers lines and signal controlling magnets therefor, each line terminally connected at a central oflice through its signal magnet to said storage battery, subscribers station apparatus including telephones and switches, a spring-jack or jacks for each line constituting open multiples thereof outside of the signal controlling magnet, operators plugs and cord circuits, and a common charging generator connected in parallel across said cord circuits, whereby the subscribers will be supplied with talking current through the cord circuits, the signal controlling magnets will be deenergized, and the common storage battery will be maintained fully charged, all substan tially as described.

In testimony whereof I have atfixed my signature in presence of two witnesses.

EDWARD E. CLEMENT.

Witnesses HUGH M. STERLING, J. L. Warorrr.

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