JPH05183651A - Sensor circuit for telephone line and its unit - Google Patents

Abstract

PURPOSE:To make the assembly space of a network control unit small. CONSTITUTION:The sensor circuit consists of line current detection means 42,44, a line current monitor means 48, and a tone extract means 50, and the line current detection means 42 consists of a detection coil 42 and the means 44 consists of a magnetic sensor 44, and they detect magnetically a line current in telephone lines 10, 12. On the other hand, the line current monitor means 48 consists of a comparator 48 and generates and outputs a monitor output of a line current from a detection output of the magnetic sensor 44 of the line current detection means and the tone extract means 50 extracts a tone signal from the detection output of the magnetic sensor 44 and outputs the signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone line sensor circuit provided in a network control unit (NCU: network control unit at the lowest layer of the telephone network) and its unit.

[0002]

2. Description of the Related Art FIG. 3 shows a configuration of an NCU using a conventional telephone line sensor circuit. In the figure, 2,
Reference numeral 4 is a terminal connected to a telephone exchange, and reference numerals 6 and 8 are relay switches. The relay switches 6 and 8 have movable contacts 6a and 8a, respectively. Movable contacts 6a, 8a
Are connected to terminals 2 and 4 via telephone lines 10 and 12, respectively.
It is connected to the. The relay switches 6 and 8 also have individual contacts 6b and 6c; 8b and 8c, respectively. One of the individual contacts 6b and 8b is connected to the primary winding 14a of the line transformer 14. The other individual contact 6c,
8c are connected to the tone extraction circuit 16, respectively.
The tone extraction circuit 16 includes a capacitor 18 and a tone extraction transformer 20.

Secondary winding 14b of line transformer 14
Is connected to a 2-wire / 4-wire (2W / 4W) conversion circuit 22. The 2-wire / 4-wire conversion circuit 22 is the line transformer 1
4 of the secondary winding 14b side of the two telephone lines at the output section 4
It is converted to a wire and connected to a signal processing circuit 24 for transmission of electronic equipment, for example a facsimile. Tone detection circuit 1
6 is connected to the signal processing circuit 24 in the facsimile.

The signal processing circuit 24 includes telephone lines 10 and 12.
It is determined whether the electric signal flowing to the device is on the side of the telephone (not shown) connected to the terminals 26 and 28 or on the side of the facsimile. , 8c side, and when the side is a facsimile side, they are switched to the individual contacts 6b, 8b side, respectively.

The line current monitoring circuit 30 is inserted in one telephone line 12. The line current monitoring circuit 30 includes a pair of photocouplers 32 and 34, and one photocoupler 32 receives a light emitting element 32a that emits light when a line current flows in the direction of arrow a, and the light emitted from the light emitting element 32a. The other photocoupler 34 includes a light emitting element 34a that emits light when a line current flows in the direction of arrow b, and a light receiving element 34b that receives the light emitted from the light emitting element 34a. ing.

The outputs of the light receiving elements 32b and 34b are output to the terminals 36 and 38, respectively.
Reference numerals 6 and 38 are connected to a hook switch on / off detection circuit of the telephone and a signal processing circuit 24. When the handset is removed and the hook switch is turned off to make a call, the line current flows in the direction of arrow a to emit light. Element 32a
Is emitted, and the emitted light is received by the light receiving element 32b, and the received light output is given to the signal processing circuit 24 via the terminal 36. Further, when the line current flows in the direction of arrow b, the light emitting element 34a emits light, and the emitted light is received by the light receiving element 34b, and the received light output is transmitted through the terminal 38 to the signal processing circuit 24.
Given to.

[0007]

In the conventional telephone line sensor circuit, the tone extraction circuit 16 is large and
In addition, it has a tone extracting transformer 20 which is an expensive electronic component, and the line current monitoring circuit 30 also
Since the photo couplers 32 and 34 are used to assemble each of them on the mounting board, there is a problem that a considerably large space is required for the assembly and the NCU becomes large.

Therefore, it is an object of the present invention to provide a telephone circuit sensor circuit and unit which can reduce the assembly space of the NCU.

[0009]

In order to achieve such an object, in a telephone line sensor circuit according to claim 1 of the present invention, a line current detection for magnetically detecting a line current in a telephone line. It is characterized by comprising means, line current monitoring means for generating and outputting a monitoring output of the line current from the detected output, and tone extracting means for extracting and outputting a tone signal from the detected output.

In the telephone line sensor circuit according to a second aspect of the present invention, the tone extracting means includes an amplifier for amplifying the detection output and a filter for performing a predetermined filtering action on the detection output. It is characterized by doing.

In the telephone line sensor unit according to a third aspect of the present invention, the same unit as the first aspect may be used.
It is characterized in that each means described in 1 is provided.

In the telephone line sensor unit according to a fourth aspect of the present invention, the same unit is used in the second aspect.
It is characterized in that each means described in 1 is provided.

[0013]

According to the present invention, the line current detecting means magnetically detects the line current in the telephone line. The detection output is given to the line current monitoring means and the tone extraction means,
The line current monitoring means outputs the monitoring output of the line current according to the detected output, and the tone extraction means extracts and outputs the tone signal according to the detected output.

In the second aspect of the present invention, the amplifier in the tone extracting means amplifies the detection output applied thereto, and the filter performs a predetermined filtering action on the detection output.

In the third or fourth aspect of the present invention, the respective means of the first or second aspect are arranged in the same unit.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram of a telephone line sensor circuit according to an embodiment of the present invention. Parts and components corresponding to those of FIG. 3 according to the conventional example are designated by the same reference numerals, and the same reference numerals are used. Detailed description of the relevant parts and components is omitted here.

In the telephone line sensor circuit of this embodiment, the detection coil 42 and the magnetic sensor 44 constituting the line current detecting means, the amplifier 46, the comparator 48 constituting the line current monitoring means, and the tone extracting circuit. 50 and 50 are configured in the same unit 40.

The detection coil 42 is connected to the telephone line 12
Each of the line currents inserted in the line current and the polarity of the line current is magnetically detected, and the magnetic sensor 44 is composed of, for example, a Hall element, detects the line current from the induced magnetism of the detection coil 42, and depending on the polarity Output different detection output. The amplifier 46 is composed of, for example, a differential amplifier, and amplifies the output from each output unit 44a, 44b of the magnetic sensor. The magnetic sensor 44 responds to the magnetism generated from the detection coil 42 when a line current flows in the direction of arrow a (one polarity) in the figure, and an amplifier 46 via the output unit 44a.
And a negative output to the amplifier 46 via the output section 44b in response to the magnetism generated from the detection coil 42 when the line current flows in the direction of arrow b (the other polarity).

The comparator 48 outputs the positive output (the output corresponding to the line current of one polarity) and the negative output (the output corresponding to the line current of the other polarity) of the amplifier 46 to the corresponding reference values V1, -V2 is compared, and the results of magnitude comparison of the positive and negative outputs with respect to the reference value are compared with terminals 36 and 38.
To the signal processing circuit 24. This output is used for detecting the off-hook of the handset or calculating the telephone charge.

The tone extraction circuit 50 comprises a DC blocking capacitor 50a, an amplifier 50b and a filter 50c which are connected in this order as shown in FIG. 2, and the DC signal from the tone signal supplied from the amplifier 46 is fed to the DC component from the DC blocking capacitor 50a. The tone signal to the amplifier 5
It is amplified by 0b, and then the noise in the tone signal is removed by the filter 50c. The filter 50c has a function as a noise removal filter for removing the noise, and
It has a function as a filter for detecting a specific tone. The filter 50c may be of a type such as a bandpass filter or a lowpass filter.

The output of the tone extraction circuit 50 is given to the signal processing circuit 24 via the terminal 52. Signal processing circuit 2
Reference numeral 4 denotes a tone extraction circuit 5 which is given from the positive and negative outputs appearing at the terminals 36 and 38 through a line current or the terminal 52.
A tone signal such as a facsimile network signal from 0 or a dial tone signal is processed, and in the case of a telephone according to the signal, the movable contacts 6a and 8a of the relay switches 6 and 8 are set to the individual contacts 6c and 8c, respectively. For electronic devices, relay switches 6 and 8 movable contacts 6a and 8 respectively
a is switched to the individual contact 6b, 8b side.

In the above-described embodiment, the tone extraction circuit 50 is the same as the detection coil 42 and the magnetic sensor 44 forming the line current detecting means, the amplifier 46, and the comparator 48 forming the line current monitoring means. Unit 4
However, the tone extraction circuit 50 may be provided outside the unit 40, for example, externally. When the tone extraction circuit 50 is provided in the same unit 40 as in the above embodiment,
The NCU assembly work can be efficiently performed.

Further, in the above-described embodiment, each of the DC blocking capacitor 50a, the amplifier 50b and the filter 50 constituting the tone extraction circuit 50 is connected in series in the order shown in FIG. However, by changing the connection order of the amplifier 50b and the filter 50c, the DC blocking capacitor 50a and the filter 5
0c and the amplifier 50b are connected in series according to this order, the DC blocking capacitor 50a
Filter 5 is first applied to the detection output in which the DC component is blocked by
The detection output may be amplified by the amplifier 50b after the required filter is applied at 0c.

Furthermore, in the above-described embodiment, the amplifier 50b is composed of an operational amplifier, and the resistor connected to determine the amplifying operation around the operational amplifier is amplified by function trimming with a laser or the like. When the detection output from the magnetic sensor 44 is varied, the function trimming is performed so that the variation is absorbed and the amplification operation of the amplifier 50b is changed, resulting in tone extraction. The circuit 50 may always obtain a stable tone signal.

Furthermore, in the above-mentioned embodiment, the tone extraction circuit 50 is adapted to be supplied with a signal from the amplifier 46 which supplies the signal to the comparator 48, but to the output sections 44a and 44b of the magnetic sensor. A separate amplifier 46 connected may be provided so that the signal is provided from this amplifier 46.

[0027]

As is apparent from the above description, according to the first and second aspects, the sensor circuit is composed of the line current detecting means, the line current monitoring means, and the tone extracting means, and the line current detecting means is provided. Means for magnetically detecting the line current in the telephone line, line current monitoring means for generating and outputting a line current monitoring output from the detection output of the line current detecting means, and tone extracting means for the same line current. Since the tone signal is extracted and output from the detection output of the detection means, a large-scale tone extraction transformer that constitutes a conventional tone extraction circuit is not required, and the NCU can be downsized.

According to the third and fourth aspects of the invention, since the units are arranged in the same unit, the NCU can be assembled efficiently.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a telephone line sensor circuit according to an embodiment of the present invention.

FIG. 2 is a specific circuit diagram of the tone extraction circuit of FIG.

FIG. 3 is a circuit diagram of a telephone line sensor circuit according to a conventional example.

[Explanation of symbols]

6, 8 ... Relay switch, 10, 12 ... Telephone line, 14
... line transformer, 24 ... signal processing circuit, 40 ... sensor unit, 42 ... detection coil, 44 ... Hall element (magnetic sensor), 46 ... differential amplifier, 48 ... comparator, 50 ... tone extraction circuit

Claims (4)

[Claims] 1. A line current detecting means (42, 44) for magnetically detecting a line current in a telephone line (10, 12), and a line current monitoring means for generating and outputting a monitor output of the line current from the detected output. A telephone line sensor circuit comprising: (48); and tone extraction means (50) for extracting and outputting a tone signal from the detection output. 2. The tone extracting means (50) includes an amplifier (50b) for amplifying the detection output, and a filter (50b) for performing a predetermined filtering action on the detection output. The telephone circuit sensor circuit according to claim 1. 3. A line current detecting means (42, 44) for magnetically detecting a line current in a telephone line (10, 12), and a line current monitoring means for generating and outputting a monitor output of the line current from the detected output. A telephone line sensor unit comprising (48) and a tone extracting means (50) for extracting and outputting a tone signal from the detection output. 4. The tone extracting means (50) includes an amplifier (50b) for amplifying the detection output and a filter (50c) for performing a predetermined filtering action on the detection output. The telephone line sensor unit according to claim 3.