DE260189C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

- JVl 260189 CLASS 21 a. GROUP

ELMER REED CORWIN in CHICAGO, V. St. A.

calling another place.

Patented in the German Empire on February 7, 1912.

The invention; refers to a telephone circuit for line dialer systems, in which each call station is provided with lockable buttons for establishing the connection is.

In particular, the invention relates to such a system in which one Call station the possibility of a connection with one already in conversation

ίο place is taken. In known circuits Such is the eavesdropping of a conversation by a person seeking a connection Participants are prevented, for example, from having his listener through a on his station The relay that is located has been short-circuited, which relay then receives power when the called subscriber had pressed a certain key on their place. in the In contrast, the present circuit not only circumvents the need to that a special button is necessary to energize the relay, but it also prevents induction currents get into the handset of the subscriber seeking connection. By exciting one Magnets on the point looking for the connection are namely two contacts that are for usually not in connection, but in conducting when a connection is made Get in touch, even farther apart, so that eavesdropping is completely out of the question. The magnet that holds the two Contacts further apart, lies in a circuit, which is also connected to a Part of the circuit of the called (and under discussion) station collapses, and is therefore excited as long as the position is filled. At the same time it closes for as long it is energized, a completely independent testing circuit that gives the caller the "Busy" character transmitted.

The contacts that are removed from each other by the test magnet when the called Position is occupied, lie in a circuit that is closed as soon as the Caller picks up the handset and remains closed when the called party answers. the Contacts are then kept in touch by another magnet that controls the The armature of the test magnet holds outside the influence of the latter.

In the drawing, the new circuit is shown schematically for three subscriber stations, which are labeled I, II and III. The three places are connected by three double lines 1, 2, 3. Each position contains two keys a, by means of which the free positions can be selected. Each dial button also controls a signal on the remote station and causes a busy signal to appear if the selected line is already busy.

An electromagnet b provided at each point establishes the connection between the calling point and a free called point. There is also an electric

magnet c in action if the position called is already occupied. It then lets a busy signal appear and in this case also prevents the establishment of a connection between the calling station and the station to be called.

The circuit also contains a central battery d, the application of which, however, is not restricted to the invention. One

ίο Power source e supplies the test and signal current. An electromagnet f acts as a self-interrupter and influences the current of the battery e for test purposes.

After these general explanations, the details of the new circuit will now be described will. Position I is assumed to be the first to send out an exclamation '. Position II is that of position I. selected. Station III is trying to get a connection at station I in the meantime.

If the subscriber I wants to have a connection with the point II, he first picks up the handset g from the hook switch and. then presses the key a completely down, which corresponds to the station to be called II or the. Line 2 heard. If point II is free, magnet b is excited at point I, in the following way: positive pole of battery d, induction coil i of line 2, contact springs α ² and «'of the pressed key a, winding of electromagnet b , Hook switch h, contact spring h ¹ , negative pole of the battery d. As long as the button a is fully depressed, the contact spring ^{4 of} the button α is on the contact spring β ¹ , so that current can flow from the battery e in the following way: positive pole of battery e, contact springs e ¹ and ⁴ , lower line 2 to point II, here via the contact springs h ^z , A ⁴ and the alarm clock I back to the negative pole of the battery e. If the key α is released after the signaling, it assumes the position shown, its return movement being prevented by a pin e ² which engages in a notch in the key. The pins e ^% are attached to a common locking bar e ³ , through the movement of which any key that has been pressed can be triggered again, and which the spring e ⁴ always tries to lift. The pressed key α on the calling station I remains in the position shown for the entire duration of the call and until the locking bar e ³ either by completely depressing this same key a - if point II is to be called again - or by completely depressing another Button • - if a station other than II is to be called - is moved. In the illustrated position of the depressed key α , its contact springs a ¹ and e ^{1 are} out of contact with the contact springs β ² and ⁴ . The armature k of the magnet b at point I is swiveled clockwise when the magnet b is excited, and then brings the contact springs k \ k ² and k ³ into contact, while at the same time the contact spring £, which is also moved by the armature k ^{4 applies} against the contact spring k ⁵ . As a result, the microphone of station I receives power in the following way: positive pole of battery d, induction coil i of line 2, contact springs a ² , a ^{3 of} the pressed button a, contact springs k ⁵ , k * of armature k, microphone and telephone g of the station I, contact springs h ² , A ³ of hook switch A, contact springs k ¹ , k ² , k ^s of armature k, winding of magnet b, hook switch A, contact spring A ¹ , negative pole of battery d. The microphone of the called point II receives power in the following way: positive pole of battery d, induction coil * of line 2 to point II, here contact springs k ⁶ , k * of armature k, microphone and telephone g, contact springs h ² , h ³ , lower Line 2, back to point I, here contact springs α ⁴ , a ⁶ of button a, contact springs k ² , k ³ of armature k, winding of magnet b, hook switch h, contact spring A ¹ , negative pole of battery d.

The speech currents between positions I and II take the following route: microphone at position I, contact springs k ^l and k ^& of armature k, contact springs a ³ , « ^{2 of} the pressed key a, upper line 2 to position II, here contact springs k ⁶ , k * of the anchor k, microphone and telephone g, contact springs h ² , h ³ des ^; Hook switch h, lower line 2, back to position I, here contact springs « ⁴ , a ^s of key a, contact springs k ² , k ^x of armature k, contact springs h ³ , h ^% of hook switch h, telephone g, microphone. According to what has been said, the ringing circuit does not expediently coincide with the speech circuit that is formed when the subscriber at the called point picks up the receiver from the hook switch.

The means by which a third digit is prevented will now be described will connect with the place just described as calling or called, and through which these positions of the third position are designated as occupied.

As can be seen from what has been said, the contact spring h ^{1 of} the hook switch is directly connected to the negative pole of the central battery d at every point, while its positive pole is permanently connected to the upper line 1 of the calling station and to the upper line 2 of the called station I and II is. The lower end of each magnet winding c can be connected to the negative pole of the central battery d via the associated hook switch h and its contact spring k ¹ , if

the hook switch is not loaded. The upper end of each magnet winding c , however, is applied to a contact spring m , with which the contact spring <? ⁴ comes into contact when the bolt ß ^{3 is} partially or completely pushed down. The contact spring g ⁴ is now permanently connected to the contact springs a ^{5 of} the buttons α at every point. If one of the two keys α is pressed completely at position III,

ίο the contact spring m connected to the magnet winding c is connected to the lower line ι or 2 and thus also to the positive pole of the central battery d. The electromagnetic winding c is therefore in the following circuit: battery d, negative pole, spring A ¹ , hook h on station III, magnet e, spring m, spring e ⁴ , spring a ⁵ of button a pressed on station III to call station I, Spring α ⁴ , lower line 1 and below

ao parts of point I, spring h ³ , spring ä ² , telephone g, spring ä ⁴ , spring k ⁵ , spring a ^s , spring α ² , coil i, positive pole of the battery d. As a result, the magnet c receives current, pivots the armature k to the left and closes the contacts 0 and η at point III. On the latter, the contacts k ¹ , k ² , k ³ are at the same time further removed from one another, so that the circuit containing the microphone and telephone g of point III remains open. As a result, that participant cannot hear anything on lines 1 or 2. On the other hand, a circuit specified below containing the microphone and telephone of station III is closed by the central battery e via the self-interrupter f , which in a known manner generates a cracking in the remote receiver g of subscriber station III to indicate to the user that the line in question is busy . The test current takes the following route: positive pole of battery e, self-interrupter f, contact 0, microphone and telephone g of position III, contact springs h ² , h ³ of hook switch h, contact n, negative pole of battery e. The test current does not get into the occupied line, it is a pure local current and it is also advisable that it does not have an inductive effect on the tested line. Although the contacts e ^l and m of a calling station that seeks to connect to a free line are closed when the key belonging to the line in question is pressed, the magnet c of the station in question receives no current because on the one to be called Place the contact springs h ² , h ^{3 of} the hook switch h are not in contact, so form an interruption in the circuit between the magnet c and the positive terminal of the battery d . If the called subscriber answers, the magnet c on the calling point I can be excited when the bolt e ^{s is} pressed down, namely by the following current: battery d, negative pole, spring A ^{1 of} the receiver hook on point I, hook h, magnet e on position I, springs m, e ⁴ , spring a ^s of the button a pressed to connect with position II, spring α ⁴ , lower line 2, springs h ³ , h ² on position II. Telephone g, springs & ⁴ , k ⁶ , top line 2, positive terminal of the battery d. This circuit probably excites magnet c at point I, but since magnet b has already been excited before subscriber II picked up his receiver, magnet c will no longer affect armature k , which is now held by b , as long as the calling party Subscriber at point I has picked up his phone from the hook switch k. If the calling subscriber hangs back the remote receiver, the circuit is closed. of the magnet b at the contact spring h ^l interrupted. Since the contact springs e ⁴ and m are then out of contact at the calling point I, the armature k returns to the normal middle position, as it is designated for the point II. In order to prevent the wrong action of the magnet c , the shafts of the keys a have sufficient dead movement with respect to their springs, so that the fully depressed key causes the bolt e ^{3 to} drop and thus also a release of all the other keys belonging to the rod causes. Furthermore, after releasing a key, the contact springs belonging to it return to the rest position earlier before the key in turn completely assumes the rest position. In this way, the current interruption between the contacts β ⁴ and a ^{s is} secured when the keys return to the rest position.

So if a point tries to establish a connection with an occupied line, its magnet c is excited in the manner described. If a connection with another line is then to be made from this point, the circuit of the magnet c between the contact springs α ⁴ and a ^{5 of} that key is interrupted by depressing the corresponding key, which leads to the line to be called before, but found occupied 'heard.

Claims (3)

Patent Claims: i. Circuit for a telephone line selector system in which an electromagnet is excited at each telephone station when the station in question calls another station in conversation, characterized in that a magnet (c) of the calling station (e.g. III) in a circuit ( d, h ^l , h for III, e, m, e ^l , a ⁵ , a ^l , 1, h ³ , h ² for I, g, k ^l , ¥>, a ³ , a ² , i, d) lies, which is closed by contacts (k ^, k ⁵ ) which come into conductive contact at every point when the respective called point (e.g. I) has already connected to an unoccupied position (e.g. II), and that this magnet (c) through its excitation an anchor swings out, which one from the conversation circuit ^ g at I, k \ k \ a ^z , a ² , 2, k ^s , k * at II, g, A ² , A ³ , 2, « ⁴ , a ⁵ at I , k ² , k ¹ , h ³ , completely un- dependent test circuit (e, f, 0, g, h ² , h ³ , n, e) closes, whose breaker (f) transmits the »busy call sign to the subscriber seeking connection (III). Circuit according to claim 1, since 2. characterized in that the armature of the magnet (c) is swung out in a direction in which the distance between the contacts necessary to establish a connection (% *, k ⁵ ) is increased, so that the participant can overhear a conversation in whose listener circuit these contacts (k ⁴ ·, k ⁵ ) lie, is made impossible. 3. A circuit according to claim 1 and 2, characterized in that, if the called location (z. B. II) is unoccupied, the separation of the contacts (k ⁱ , k ⁵ ) despite the excitation of the magnet through which current flows each time a connection is established ( c) on the calling point (e.g. I) is prevented by another previously excited magnet (b) at the same point, which remains excited when each connection is established and the armature of the magnet (c) in an area outside the area of the magnet ( c) holds the position. 1 sheet of drawings.