JPH01311673A - Voice signal transmission equipment - Google Patents

Abstract

PURPOSE:To improve packaging efficiency on a printed board by reducing the number of components comprising a circuit to absorb AC inductance by providing a capacitive element between an end part not being connected to a subscriber terminal and the ground at the primary winding separated into two parts of a transformer. CONSTITUTION:When the AC inductance is generated by the influence of a signal other that a voice e.g., an external AC source, the signals are generated at both ends of the primary winding of the transformer 115. The primary winding of the transformer 115 is separated into two parts, and the circuit formed by two winding and two capacitive devices 117 and 119 absorbs a certain range of frequency. Therefore, by performing the adjustment of impedance so as to absorb an inducive component by the circuit, no influence of the induction due to the external AC power source on another circuit in a device can be given. Thus, by utilizing the primary winding of the transformer 115 and forming the absorption circuit of the AC inductance by connecting the capacitive devices 117 and 119, it is possible to reduce the number of packaging components on the printed board.

Description

[Detailed Description of the Invention] [Summary] Regarding an audio signal transmission device that has a function of absorbing AC induced components occurring in a path for transmitting an audio signal, the purpose of reducing the number of circuit components is to reduce the number of circuit components. A power supply means for supplying the necessary power between the subscriber terminal of the type and ground so that audio signals can be transmitted by the subscriber terminal; a transformer having a primary winding connected to two wires of The apparatus is configured to include a capacitive element and an audio signal processing means that is connected to the secondary winding of the transformer and performs desired processing on the transmitted audio signal.

[Industrial application field]

The present invention relates to an audio signal transmission device, and more particularly to an audio signal transmission device having a function of absorbing AC induced components occurring in a path for transmitting an audio signal.

[Conventional technology]

FIG. 3 shows a conventional example of an audio signal transmission device that digitally processes and transmits an audio signal, in which AC induced components generated therein are removed.

In the figure, the audio signal transmission device includes a PBX and a subscriber terminal such as a telephone (not shown) at one T terminal and one R terminal.
and on the other hand, a pulse code change All (PCM) circuit 2 for digital signal processing via a transformer 313.
It is connected to 07.

Here, the T terminal is the transmitting side, and the R terminal is the receiving side.

Further, the current supply circuit 205 supplies DC current for operating a subscriber terminal, such as a telephone. This direct current flows through the circuit including the telephone, and the voltage state varies depending on the operating state of the telephone.
By measuring this voltage with the detection circuit 201 connected between TR and R, it is possible to detect a calling signal or use.

Further, from the T terminal and the R terminal, if the device is in use, a signal current (alternating current) having a frequency corresponding to the voice is sent.

This current is generated on the secondary side of the transformer 313 and converted into a digital signal by the PCM circuit 207. This transformer 313 is also called an audio transformer because it handles audio signals.

At present, a considerable number of telephones are widely used throughout the world. As a result, telephone lines will be installed all the way to each telephone. The wiring for this telephone line is usually handled separately from electric wires (not shown) that supply commercial alternating current voltage. However, depending on the region, this AC voltage supply wire and telephone line may be installed in parallel, and in that case, the current flowing through the AC voltage supply wire may have an effect on the telephone line. There was a problem called (interchange induction).

Such an AC induced current has the same frequency as the AC voltage (5
0 Hz or 60 Hz), and there is a risk that the detection circuit 201 connected to the telephone line where the inductive component occurs may malfunction. In order to eliminate this malfunction, an AC induction absorption circuit 303 is provided in front of the detection circuit 201.

In the AC induction absorption circuit 303, two capacitors 321 and 323 and a transformer 311 are connected in series between the T and R terminals, and the impedance is set so as to absorb the current component of the AC voltage frequency. Therefore, when an AC induced current from the AC voltage supply wire occurs at the T@ and R terminals, the AC induced current is absorbed by the AC induction absorption circuit 303 and is designed to prevent it from entering the detection circuit 201. There is.

The AC induced current has the same frequency as the commercial AC voltage, 50 H2 or 60 Hz. By the way, since the audible range starts around 40 Hz, this AC induced current is also included in the range that is recognized as voice. The AC induction absorption circuit 303 also absorbs audio signals of 50Hz or 60Hz, but the frequency band that is particularly problematic for telephones is between 300Hz and 3000H2.
Even if 0H2 is removed before transformer 313, it will not have a significant effect in practice.

Audio signals input from the T terminal and the R terminal are transformed in a transformer 313 for the PCM circuit 207.

When transforming the voltage, a small capacitor 325 is used because DC current flows in the circuit for the operation of the telephone.
is added before the transformer 313 to remove the DC component,
Only alternating current, which is an audio signal, is supplied to the PCM circuit 207.

[Problem to be solved by the invention]

By the way, in the conventional method described above, two capacitors 321 and 3 are used to remove the current caused by AC induction.
AC induction absorption circuit 30 comprising 23 and a transformer 311
3, there was a problem that the number of parts increased and the mounting efficiency on the printed circuit board was poor.

The present invention was created in view of these points, and an object of the present invention is to provide an audio signal transmission device that can reduce the number of parts and improve mounting efficiency.

[Means to solve the problem]

FIG. 1 is a block diagram of the principle of the audio signal transmission device of the present invention.

In the figure, the power supply means 113 is connected to the two-wire subscriber terminal 111 and supplies the necessary power to the ground so that the subscriber terminal 111 can transmit audio signals.

The transformer 115 has a primary winding that is separated into two halves and each end connected to the subscriber terminal 11102 line.

Two capacitive elements 117, 119 are provided in the primary winding of transformer 115 between each of the ends not connected to subscriber terminal 111 and ground.

The audio signal processing means 121 is connected to the secondary winding of the transformer 115, and performs desired processing on the transmitted audio signal.

Therefore, the overall configuration is such that the audio signal from the subscriber terminal 111 is supplied to the audio signal processing means 121 via the transformer 115.

[For production]

The audio signal from the subscriber terminal 111 is generated at both ends of the primary winding of the transformer 115, transformed by the secondary winding, and supplied to the audio signal processing means 121.

Additionally, when an AC induction occurs under the influence of a signal other than audio, for example an external AC source, a signal is generated across the primary winding of the transformer 115.

The primary winding of the transformer 115 is separated into two parts,
These two windings and two capacitive elements 117.119
The circuit formed by absorbs components in a certain range of frequencies.

Therefore, if the impedance of this circuit is adjusted so as to absorb the inductive component, the influence of induction by the external AC power supply on other circuits in the device will be eliminated. Malfunctions of the circuit (not shown) are eliminated.

In the present invention, since the primary winding of the transformer 115 is used and the capacitive element is connected to form an AC induction absorption circuit, the number of mounting points on the printed circuit board can be reduced.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 shows the configuration of an audio signal transmission device in an embodiment of the present invention.

2. Correspondence between Example and FIG. 1 Here, the correspondence between the embodiment of the present invention and FIG. 1 will be shown.

Power supply circuit 113 corresponds to current supply circuit 205.

Capacitive elements 117 and 119 are capacitors 211°213
corresponds to

Transformer 115 corresponds to transformer 215.

The audio signal processing means 121 corresponds to the PCM circuit 207.

Examples of the present invention will be described below assuming that the correspondence relationship as described above exists.

Figure 2 shows an audio signal transmission device according to an embodiment of the present invention, in which the same symbols as in the conventional example indicate corresponding circuits, and the details thereof will be omitted.

In the figure, the T@ and R terminals are connected to a subscriber terminal (not shown) such as a telephone. T terminal.

A current supply circuit 205 that supplies current to a telephone set as a subscriber terminal, and a detection circuit 201 that detects a usage state are connected in parallel between the R terminals. Furthermore, an AC induction absorption circuit 203 that transforms the audio signal and absorbs AC induction is connected.

The AC induction absorption circuit 203 includes a transformer 215 for audio signal transformation, the primary winding of the transformer 215 is separated into two at the midpoint, and two capacitors 211. It is grounded through 213. transformer 2
Both ends of the primary winding 15 are connected to the T terminal and the R terminal, respectively, and both ends of the secondary winding are connected to the input end of the PCM circuit 207.

(2) Embodiment q Excitation Next, the operation of the two-part audio signal transmission apparatus according to the embodiment of the present invention will be described.

A current supply circuit 205 supplies direct current necessary for the operation of the telephone, and a detection circuit 201 detects the flow of the direct current.

For example, when a telephone is in use, an alternating current, which is an audio signal, flows from the T and R terminals, and the alternating current is transmitted to the transformer 2.
15 and processed by the PCM circuit 207.

By the way, if an AC voltage supply line (not shown) from a commercial power source is nearby, AC induction will occur.

Since the AC induction absorption circuit 203 including the transformer 215 and the detection circuit 201 are connected in parallel, by changing the circuit constant settings of the AC 2IT induction absorption circuit 203, the AC induction absorption circuit 203 can be adjusted to a specific frequency. By performing processing to increase the current flowing through the detection circuit 201, the current flowing through the detection circuit 201 can be reduced.

For example, with respect to the frequency of AC induction, the impedance of the circuit formed by the two capacitors 211 and 213 and the primary winding of the transformer 215 is set to be small, and the impedance of the detection circuit 201 is set to be large. Just do it. As a result, at the branch point between the detection circuit 201 and the AC induction absorption circuit 203, a large current flows into the AC induction absorption circuit 203, which has a small impedance, and a small current flows into the detection circuit 201, which has a large impedance.

Therefore, the frequency of the AC induced component (50Hz or 60Hz)
Two capacitors 21 are connected so that the absorption characteristics match the
1,213 and the primary winding of the transformer 215, the detection circuit 201
It is possible to reduce the alternating current induced current flowing into the

Therefore, the difference from conventional audio signal transmission devices is that a circuit for absorbing AC induced current is installed between the subscriber terminal and the detection circuit 201.
Instead of having it between the detection circuit 201 and the PCM circuit 207.

■Summary of the embodiment As described above, in the audio signal transmission device of this embodiment, the AC induction absorption circuit 203 for removing AC induction components uses the transformer 215 for audio signal processing, and the primary The side winding is separated into two parts, with 2
Two capacitors are connected in series, and the impedance is set to be low with respect to the AC induction frequency, so that the AC induction frequency current flowing into the detection circuit 201 is made small. Therefore, the AC induction does not affect the detection operation by the detection circuit 201.

Therefore, the transformer 215 is included in the circuit that absorbs the AC induced component.
and newly installed capacitors 211, 21
3 can cut the DC component, so there is no need for a separate capacitor to block the DC component.

Therefore, the number of parts on the printed circuit board can be reduced.

(1) Modifications of the invention In the above-described embodiments of the invention, the audio transformer was used for absorbing AC induction, but other transformers may be used.

Further, the present invention is not limited to the embodiments, and those skilled in the art can easily imagine that there are various modifications.

〔Effect of the invention〕

As described above, according to the present invention, the number of circuit components that absorb AC induction can be reduced and the mounting efficiency on a printed circuit board can be increased, so that the present invention is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a configuration diagram of an audio signal transmission device according to an embodiment of the present invention, and FIG. 3 is an explanatory diagram of a conventional example. In the figure, 111 is a subscriber terminal, 113 is a power supply means, 115 is a transformer, 117.119 is a capacitive element, 201 is a detection circuit, 203.303 is an AC induction absorption circuit, 205 is a current supply circuit, and 207 is a current supply circuit. PCM circuit, 211.213, 321, 323, 325 are capacitors, 215.311, 313 are transformers. ] 94 Tokuaki no Kuri Kakeru O...7shiJ Figure 1 1-et
engineering

Claims (1)

[Claims] (1) A power supply means (113) for supplying necessary power between a two-wire subscriber terminal (111) and ground so that the subscriber terminal (111) can transmit audio signals; , separated into two parts, each end of which is connected to the subscriber terminal (1).
a transformer (115) having a primary winding connected to two wires of the transformer (11); and an end of the primary winding of the transformer (115) that is not connected to the subscriber terminal (111). Two capacitive elements (117, 1
19); and an audio signal processing means (121) connected to the secondary winding of the transformer (115) and performing desired processing on the transmitted audio signal. Features of the audio signal transmission device.