DE1159041B - Circuit arrangement for telephone sets in automatic telephone exchanges - Google Patents

Description

GERMAN

PATENT OFFICE

N22079Vffla / 21a ³

REGISTRATION DATE: SEPTEMBER 11, 1962

NOTICE
THE REGISTRATION
AND ISSUE OF
EDITORIAL: DECEMBER 12, 1963

The invention relates to a circuit arrangement for telephone sets in automatic telephone exchange systems with wire transmission of audio frequency dialing signals from the apparatus to a receiver, in the apparatus at the same time means for Sending voice signals over the same line are provided.

Tone frequency dialing signals can be simulated by speech signals. It is therefore important to protect the dial signal receiver from speech signals. It has already been suggested while shorting the microphone to the generation of a tone frequency dial signal in a telephone set. However, this does not offer any protection in the idle period between two dialing signals. Further it was proposed to use a common additional signal together with the dialing signals Direct current change of the line to transmit, which the dial signal receiver for the dial signal makes sensitive. It is also known, in a telephone set, the microphone via one in only to feed one direction permeable element and while dialing one that blocks the element Apply supply voltage. These solutions have disadvantages in electronic telephone exchanges because the line is then fed from the line circuit.

According to the invention it is proposed the means for transmitting speech signals over the line to be switched on only after you have finished dialing.

The circuit according to the invention has the characteristic on that there is a relay in the apparatus, which in the rest position the means mentioned locks and unlocks these means in the operating position, and that means are provided on the receiving side are that after the reception of the dialing signals on the part of the receiver, the relay in the operating state lead, with the relay having a normally open contact and its own winding, a supply source and a Hook switch, which is closed when the device is started up, itself in the operating state holds.

This circuit offers the advantage that the switching means on the receiving side are only effective for a short time need to be to energize the relay continuously.

The invention is explained in more detail using an example shown in the drawing.

The figure shows, partly in detail, the circuit of a telephone set 1 which is connected via the lead wires L 1 and L 2 to a dial signal receiver 2 in an automatic telephone exchange. Dial circuitry is located in the telephone set

for telephone sets in automatic

Telephone exchanges

Applicant:

NV Philips' Gloeilampenfabrieken,
Eindhoven (Netherlands)

Representative: Dr. rer. nat. P. Roßbach, patent attorney,
Hamburg 1, Mönckebergstr. 7th

Claimed priority:
Netherlands of September 15, 1961 (No. 269 292)

Roelof Reinier van der Veen,

Hilversum (Netherlands),
has been named as the inventor

signal generator 3 with selector keys 4. The hook switch has the contacts Hl to H 3, which are closed when the handset is removed. The microphone 5, the replica transmitter 6, the telephone 7 and the line replica 8 form the usual speech circuit. In the telephone set there is also a signal receiver 9 which is switched on between the lead wires L 1 and LI . An acoustic alarm clock 10 is connected to the signal receiver in the idle state.

When the hook switch H 1 is closed, the selection signal generator 3 can transmit audio frequency selection signals to the selection signal receiver 2 via the line wires Ll and Ll. The pushbuttons 4 each correspond to a specific signal frequency or a specific combination of signal frequencies. The dial signal generator can be of any known type.

A selection signal, the frequency of which is in the audio frequency range, can be generated by a signal from the microphone 5 be faked. In this case, the problem arises, the dialing signal receiver in the telephone exchange to protect against disturbing microphone signals. According to the invention it is proposed that the microphone to be connected to the lead wires only after you have finished dialing. That way will Avoid having to use the microphone while dialing

309 768/103

signals can be transmitted over the lead wires to the dial signal receiver.

According to the invention, the telephone set has a relay with the windings R 1 and if? 2 and a changeover contact r. The winding R 1 is connected to the signal receiver 9 when the hook switch H 3 is closed.

When the handset is removed, the hook switches H 1 to H3 are closed. A subscriber can now dial the desired number by pressing the 4 keys. The dial signal generator transmits the audio frequency dial signals via the changeover contact r and the line wire Ll and via the hook switch Hl and the line wire L 2 to the dial signal receiver 2. After the dial signal receiver 2 has received the full number, it sends an audio frequency signal via the line wires L 1 and Ll to the subscriber set. In telephone systems with subscriber numbers with a fixed number of digits, the recipient can * ° determine the end of the number from the number of digits dialed. In other systems, the dial signal generator can be provided with an additional dial button which can signal the end of the number dialing to the dial signal receiver. »5 In the subscriber set, the audio frequency signal is evaluated by the signal receiver 9 and the relay winding Al is excited. The relay moves its changeover contact r and thereby connects the speech circuit with the lead wires. On the other hand, the changeover contact separates the selection signal generator 3 from the lead wires. The buzzing tone, which signals that the subscriber can start dialing, can be made audible in the telephone that the active side of the changeover contact r is bridged by the series connection of a resistor and a capacitor, as shown in dashed lines in the figure. The capacitor blocks the direct current for the microphone and lets the buzzing sound through.

The signal receiver 9 has an oscillating circuit 11 which is matched to the signal of the selection signal receiver 2 and which is switched on in the base-emitter circuit of a transistor 12. The signal is fed to a tap of the resonant circuit via an isolating capacitor 13. When the hook switch H 3 is closed, the relay winding R 1 lies between the collector electrode of the transistor 12 and a feed point 14. This point is the connection point between a choke coil 15 and a capacitor 16, which is connected in series with the changeover contact r between the lead wires. The capacitor 16 is charged to the voltage between the lead wires, which are fed with direct voltage in the telephone exchange in a known manner. The choke coil 15 has a high impedance for speech currents. During the negative peak of the voltage generated at the oscillating circuit 11, the transistor 12 is conductive. The pulse-shaped collector current excites the relay winding R 1, which is attenuated by a diode 17 lying parallel to it. By moving the changeover contact r , the connection between the feed point 14 and the conductor L 1 is interrupted. The voltage of the feed point decreases, as a result of which the signal receiver 9 becomes insensitive to the speech currents.

In series with the separating capacitor 13, a threshold circuit can be included, which is normally has a low threshold value and when the voltage is removed from the feed point 14 receives a high threshold value that cannot be exceeded by the speech streams, so that the input of the signal receiver 9 does not divert the speech currents and does not weaken them will.

A winding R 2 of the relay is located in the speech circuit. By switching the changeover contact r, the relay closes a holding circuit for itself via the winding /? 2 and the hook switch H 1. When the handset is put on, the hook switch Hl opens the holding circuit and the relay drops out. The relay winding R 2 forms part of the line replica 8, which can be adjusted by means of the resistor 18 and the capacitor 19, in the manner shown.

In the case of an incoming call, an audio frequency wake-up signal with the same frequency as the tuning frequency of the oscillating circuit 11 is fed to the subscriber set from the telephone exchange. The hook switch H 3 connects the alarm clock 10 to the signal receiver 9 in the idle state, so that the alarm clock makes the alarm signal audible. After the call has been answered, the handset is picked up. The hook switch H 3 connects the relay winding R 1 to the signal receiver and interrupts the connection with the alarm clock 10. The hook switch Hl switches the dial signal generator 3 between the line wires. This allows the answering of the call to be signaled to the telephone exchange by the subscriber set. After receiving the answer signal, the telephone exchange continues to transmit the wake-up signal until the wake-up signal has energized the relay in the subscriber set. The speech circuit is then connected to the lead wires.

Claims (1)

PATENT CLAIM: Circuit arrangement for telephone sets in automatic telephone exchange systems with wire transmission of audio frequency dialing signals from the device to a receiver, with means for transmitting voice signals over the same line being provided in the device at the same time, characterized in that a relay is present in the device, which in the idle state the mentioned Means locks and unlocks this means in the operating state, and means are provided on the receiving side, which lead the relay into the operating state after receipt of the selection signals by the receiver, the relay via a normally open contact and its own winding, a supply source and a hook switch that is closed when the device is started up, keeps itself in the operating state. 1 sheet of drawings ® 309 768/103 12.