JPS5915174Y2 - Audio frequency signal, power and digital pulse transmission circuits in main equipment and terminal equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transmission device that performs bidirectional audio frequency signal transmission, bidirectional digital pulse transmission, and unidirectional power transmission between a main device and a terminal in a key telephone device or switching device.

For example, in a button telephone device, audio frequency signals, control signals, and lamp signals are exchanged between the main device and the terminal, and power is supplied from the main device to the terminal.

For this reason, conventionally, the main device and the terminal are connected using a cable that includes a telephone line that transmits audio frequency signals, a control line, a lamp line, and a power line, but this has the disadvantage that the cable becomes thicker. .

As the number of station lines and terminal equipment increases, the number of required transmission lines and therefore the number of cable cores increases.

For example, 10 central office lines and 30 button telephones as terminals.
In a large device that accommodates a stand, the number of cable cores may reach as many as 100.

For this reason, (1) the cables, connectors, and labor costs required for construction are extremely expensive, and (2) when attempting to add individual new service functions to key telephones, the number of cable cores increases even more. There are disadvantages such as the need to change the wiring between the device and the key telephone, which requires cost and labor.

For this reason, efforts have been made to reduce the number of transmission lines between the main device and the terminal, and therefore the number of cable cores.

Figure 1 shows an example of such a device. In the figure, 1 is the main device, 2 is the terminal, 3 is the audio path using two wires, and 4' is the digital connection from the main device to the terminal. pulse transmission line,
4" is the digital pulse transmission line from the terminal to the main device, 5
', 5'' are audio frequency circuits, 11', 11'' are digital pulse transmission circuits, 12', 22', 12'', 22'' are pulse transformers with center taps, and 10' is a phantom for both digital pulse transmission lines. 23' and 23'' are digital pulse receiving circuits, and 21' is a power supply circuit for the terminal.

According to this method, information transmission between the main device and the terminal is performed using two sets of two wires that perform unidirectional digital pulse transmission, and power is supplied by a phantom of the bidirectional digital pulse transmission path, so the cable This is a high-quality public address telephone that separates audio from both directions and connects it to the main device, as it requires 6 wires and cannot use existing 4-wire cables, and there is only one set of transmission paths for audio frequency signals. When adding service functions such as a busy call function that allows voice calls even when a key telephone is busy, a complex circuit is required to time-share calls between the main unit and the terminal. It is expensive.

The present invention eliminates the drawbacks of the conventional method described above, and connects the main device and the terminal with 4 wires, and uses the 4 wires to transmit two bidirectional audio frequency signals, power, and bidirectional digital pulse transmission. In this way, it is possible to economically provide a button telephone device having advanced functions and greatly reducing the number of cable cores.

The present invention will be explained below with reference to the embodiment shown in FIG.

In FIG. 2, 1 is a main device, 2 is a terminal, and in this embodiment a key telephone is used.

3 is the two wires of the cable that connects the main device and the key telephone;
4 is the other 2 cables connecting the main device and the key telephone
line, 5 is the first audio frequency circuit, 6 is the first audio frequency transformer with a center point tap, 7 is the second audio frequency path, 8 is 3
This is a second audio frequency transformer having a winding, and a capacitor 9 is provided between the two windings to bypass the audio frequency signal, and both ends of the transformer are connected to a power transmission circuit 10 so that DC power can be supplied. I have to.

11 is a digital pulse transmitting/receiving circuit, 12 is a pulse transformer with a center tap, 13 is a bridge type transformer used in the first audio frequency circuit, 14 is an audio frequency receiving circuit,
15 is a balanced termination circuit for a bridge type transformer, 16 is an audio frequency transmitting transformer with a center tap, 17 is a transmitting circuit, 18 is a second audio frequency transformer having three light beams,
A capacitor 20 is provided between the two windings to bypass the audio frequency signal, and DC power is led from both ends of the capacitor 20 and voltage is adjusted by a power supply circuit 21 to supply power to the electronic circuit within the key telephone.

19 is a second audio frequency circuit, 22 is a pulse transformer with a center tap, and 23 is a digital pulse transmitting/receiving circuit.

Next, the operation will be explained.

The audio signal applied to the first audio frequency circuit 5 of the main device 1 is transmitted to the audio frequency receiving transformer A of the bridge type transformer 13 of the terminal device 2 via the audio frequency transformer 6 and the cable 3.
The signal is transmitted to the audio frequency reception circuit 14 terminated at the terminal.

At this time, the balancing termination circuit 15 is used for balancing line impedance.

In the terminal 2, the audio signal applied to the transmitting circuit 17 is transmitted to the midpoint of the audio frequency receiving transformer A and the midpoint of the coils B and C of the bridge type transformer 13 via the audio frequency transmitting transformer 16. The signal is transmitted to the audio frequency circuit 5 through the cable 3 and the audio frequency transformer 6 of the main device 1, so that audio signals between the main device 1 and the terminal 2 can be transmitted in both directions via the cable 3 at the same time.

Regarding the transmission of digital pulses, when a pulse to be transmitted is applied to the digital pulse transmitting/receiving circuit 11 of the main device 1, the digital pulse transmitting/receiving circuit passes through the pulse transformer 12, the cable 4, and the pulse transformer 22 of the terminal device 2. The signal is transmitted to the receiving circuit No. 23.

Further, the digital pulse sent out from the terminal device 2 is applied to the transmitting circuit of the digital pulse transmitting/receiving circuit 23, and is transmitted to the digital pulse transmitting/receiving circuit 11 via the pulse transformer 22, the cable 4, and the pulse transformer 12 of the main device 1. transmitted to the circuit.

By repeating pulse transmission alternately, digital pulse transmission between main device 1 and telephone 2 can be performed via cable 4.

The DC power required by the terminal device 2 is transmitted from the power transmission circuit 10 of the main device 1 to the 2nd and 3rd windings of the second audio frequency transformer 8, and to each of the first audio frequency transformer 6 and pulse transformer 12. From the center tap, connect cable 3 in a well-balanced manner.
, 4 to the terminal 2.

In this way, the DC power from the main device 1 is transmitted to the midpoint tap between the transformer A of the bridge type transformer 13 of the terminal device 2 and the point P between the coils B and C, the midpoint tap of the audio frequency transmitting transformer 16, The signal is supplied to the power supply circuit 21 in a well-balanced manner through the center tap of the pulse transformer 22 and the second and third windings of the second audio frequency transformer, and serves as a power source for the terminal.

Further, the audio signal applied to the second audio frequency circuit 7 of the main device 1 is transmitted via the second audio frequency transformer 8 and the bypass capacitor 9 to the tap at the center of the first audio frequency transformer 6 and the pulse transformer 12. The DC power is transmitted to the terminal device 2 in a well-balanced manner via the cables 3 and 4 weighted with DC power.

In the terminal device 2, this audio signal is transmitted to the midpoint tap of the bridge type transformer A, the coil B and the P point between the coils, the midpoint of the audio frequency transmitting transformer 16, the midpoint of the pulse transformer 22, the bypass capacitor 20 and the second The second audio signal appears in the second audio frequency circuit 19 through the audio frequency transformer 18 and is transmitted from the main device 1 to the terminal 2.

On the other hand, the audio signal applied to the second audio frequency circuit of the terminal device 2 follows the reverse communication path as described above, appears at the second audio frequency circuit 7 of the main device 1, and is transmitted between the main device 1 and the telephone 2. audio signals can be simultaneously transmitted in both directions via the cables 3 and 4.

In the figure, the first audio frequency circuit is composed of a semiconductor circuit switch in this embodiment, and the first audio frequency transformer 6 is used to adjust the difference in electrical conditions inside and outside the main device. This audio frequency transformer 6 is equipped with a center tap to form a phantom, and the transmission of the DC power and the second audio frequency signal emitted from the second audio frequency circuit on the main device side can be carried out almost economically. This makes it possible without any significant increase.

In button telephones, a hybrid circuit is normally used to supply the receiving current to the receiver of the handset and send the transmitting current from the transmitter to the line, but in this embodiment, a bridge type transformer 13 is used. An audio frequency transmitting transformer 16 is provided in the transmitting circuit, and a phantom is formed by the tap at the center of the transformer, thereby realizing the transmission of DC power and the second audio frequency signal.

According to this configuration, the audio frequency transmission transformer 16 is required, but since the bridge type transformer is balanced with respect to the above-mentioned DC power, there is no DC excitation of the magnetic core, and the second
Since the audio frequency signal does not leak into the first audio frequency signal, the price increase of the bridge type transformer is small.

Furthermore, the receiving circuit of a button telephone is equivalent to the circuit of a general telephone, and there is no transformer involved to create a phantom configuration, so the desired function can be achieved without being disadvantageous in terms of transmission loss. This provides great practical convenience.

Regarding the digital pulse transmission circuit, a phantom is constructed by using center taps in the pulse transformers 12 and 22 at both ends of the circuit, and the pulse transformer is used to transmit DC power and the second audio frequency signal. is small.

In this way, high-quality transmission with little transmission loss is possible for the first audio frequency signal, and high-speed pulse transmission is possible through balanced transmission using a pulse transformer for digital pulse transmission. By performing bidirectional transmission with opposing pulse transformers, the number of cable cores is significantly reduced, and a phantom is configured with the center tap of different types of transformers to realize the transmission of the second audio frequency signal and DC power. There is.

Furthermore, although the second audio frequency signal has a higher transmission loss than the first audio frequency signal, since it is used for calls between extensions, there is no problem in practical use. A multi-function button telephone device with as many as 100 wires was converted into 4
Since it can be realized using cables, it is distantly related to the economical use of cables and the labor saving of construction work, and has great practical effects.

Furthermore, since the number of cable cores can be reduced to four, existing standard wiring cables can be used, so in addition to the above-mentioned advantages, it saves resources and is socially useful.

[Brief explanation of the drawing]

Figure 1 shows a conventional audio frequency signal, power, and digital pulse transmission circuit between the main device and the terminal, and Figure 2 shows the audio frequency signal, power, and digital pulse transmission circuit between the main device and the terminal according to the present invention. FIG. 2 is a circuit diagram showing an example of the case where this is used in a button telephone device. In the diagram, 1 is the main device, 2 is a button telephone that is a terminal, and 3
, 4 is the two wires of the cable connecting the main unit and the button telephone, 5 is the first audio frequency circuit, 6 is the first audio frequency transformer 7.19 is the second audio frequency circuit, 8°18 is the second audio frequency circuit audio frequency transformer, 9 and 20 are capacitors, 10 is a power transmission circuit, 11.23 is a digital pulse transmission/reception circuit, 12
．． 22 is a pulse transformer, 13 is a bridge type transformer,
14 is an audio frequency receiver circuit, 15 is a balanced termination circuit, 16
17 is an audio frequency transmitting transformer, 17 is a transmitting circuit, and 21 is a power supply circuit.

Claims (1)

[Claims for Utility Model Registration] The main device 1 and the terminal 2 are connected by four wires, two of the four wires are used as a bidirectional voice communication path, and the other two wires are used for bidirectional digital pulse transmission. and (b) a first audio frequency transformer 6 whose primary side is terminated with the first audio frequency circuit 5 and whose secondary side is provided with a center tap; A second circuit terminates in the audio frequency circuit 7, has a capacitor 9 connected in series between the secondary winding and the tertiary winding, and has a power transmission circuit 10 provided at both ends of the capacitor 9.
an audio frequency transformer 8; (c) a pulse transformer 12 whose primary side is terminated with a digital pulse transmitting/receiving circuit 11 and whose secondary side is provided with a center tap;
, the midpoint tap of the first audio frequency transformer 6 is connected to one of the two windings connected to the capacitor of the second audio frequency transformer 8, and the other is connected to the midpoint tap of the pulse transformer 12; On the other hand, on the terminal device 2 side, (d) a transformer A whose primary side is terminated with the audio frequency reception circuit 14 and whose secondary side is provided with a center point tap, and a coil B which is connected in series with a center point P; (e) a bridge type transformer 13 consisting of a coil C, one end of the secondary side of the transformer A and one end of the coil C are terminated with a balanced termination circuit 15; (e) the primary side is terminated with a transmitting circuit 17; , a middle point tap is provided on the secondary side, the audio frequency transmitting transformer 16 is connected, and the primary side is terminated with the second audio frequency circuit 19, and the secondary winding is connected in series between the secondary winding and the tertiary winding. a second audio frequency transformer 18 to which a capacitor 20 is connected and a power supply circuit 21 provided at both ends of the capacitor 20; The pulse transformer 22 is connected to the midpoint tap of the transformer A of the bridge type transformer 13 to one end of the secondary side of the audio frequency transmitting transformer 16, and the other end to the midpoint P of the bridge type transformer 13. Then, the midpoint tap of the audio frequency transmitting transformer 16 is connected to the capacitor 2 of the second audio frequency transformer 18 on the terminal device 2 side.
0 is connected to one of the two windings, and the other is connected to the center tap of the pulse transformer 22 on the terminal 2 side, and the secondary side of the first audio frequency transformer 6 of the main device 1 and the terminal Connecting the other end of the secondary side of the transformer A of the bridge type transformer 13 of the machine 2 and one end of the coil B with the two wires,
The voice communication path is formed, and the secondary sides of the pulse transformers 12 and 22 on the main device 1 side and the terminal device 2 side are connected to form a digital pulse transmission path, and power is sent out on the main device 1 side. An audio frequency signal, power, and digital pulse transmission circuit between a main device and a terminal, characterized in that power is transmitted from the circuit 10 to the power supply circuit 21 on the terminal 2 side.