JPH07264638A - Power receiving circuit - Google Patents

Abstract

PURPOSE:To send distortionless clear dial pulses by disconnecting a capacitor when the dial pulses are generated by a loop part. CONSTITUTION:The loop part 20 sends the dial pulses out to a line according to the control signal which is supplied to a terminal LPIN from a control part 30. Here, a terminal RI of the control part 30 is supplied with the output RI out of a ring-back tone detecting circuit 40 which detects the ring-back tone from an exchange 100 and a terminal D of the control part 30, on the other hand, is supplied with the output Dout of a dial tone detecting circuit 50 which detects the dial tone from the exchange 100. Further, the ON/OFF operation of a switch SW1 is controlled with the control signal outputted from a terminal Dp of the control part 30. In this constitution, the switch SW1 disconnects the capacitor C1 when the dial pulses are generated and connects the capacitor C1 during a telephone call to control an AC signal to high impedance to lines Tip and Ring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power receiving circuit, and in particular,
The present invention relates to a power receiving circuit of an exchange such as a PCM primary group terminal device.
In recent years, there has been a severe demand for improvement in characteristics of PCM primary group terminal equipment. In particular, since there are severe demands on signaling characteristics, it is desired to provide a power receiving circuit that can sufficiently satisfy such signaling characteristics.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram showing a configuration of an example of a conventional power receiving circuit. In the figure, reference numeral 10 is a bias unit, 20 is a loop unit, and 30 is a control unit. As illustrated in FIG. 10, the power receiving circuit includes a bias unit 10, a loop unit 20, and a control unit 30, and in the bias unit 10, the Tip-Rin of the power receiving circuit is included.
The capacitor C1 is connected so that the impedance between g is a high impedance with respect to the AC signal (audio signal).

The loop section 20 flows most of the received power, and the control section 30 controls the operation of the power receiving circuit.
Here, the dial pulse is transmitted by turning on / off the loop unit 20 by a control signal from the control unit 30.

[0004]

In the above conventional power receiving circuit, when the dial pulse is transmitted, the loop unit 20 is used.
Are turned on and off, but at this time, the capacitor C1 provided in the bias section 10 is also repeatedly charged and discharged. Therefore, the on / off operation of the loop unit 20 is also affected by the charging / discharging of the capacitor C1, and as a result, a distorted dial pulse is transmitted.

The present invention has been made in view of the above problems of the conventional power receiving circuit, and an object of the present invention is to send a clear dial pulse without distortion.

[0006]

FIG. 1 is a block diagram showing the principle configuration of a power receiving circuit according to the present invention. According to the present invention, the dial pulse is sent to the bias section 10 having the first resistance means R1 and the capacitance means C1 connected in series between one Tip and the other Ring of the line, and the lines Tip, Ring. A loop unit 20, a control unit 30 that controls the loop unit 20, and the capacity means C for the lines Tip and Ring.
There is provided a power receiving circuit characterized by comprising a switch means SW1 for controlling the disconnection of 1.

[0007]

According to the power receiving circuit of the present invention, the switch means SW
1 controls the disconnection of the capacitance means C1 provided in the bias unit 10 from the lines Tip and Ring. here,
In FIG. 1, reference numerals Vt, Vr, Va indicate power supply means. That is, the switch means SW1 connected in series to the capacitance means C1 disconnects the capacitance means C1 when the dial pulse is generated by the loop unit 20 to eliminate the distortion of the dial pulse by the capacitance means C1, and also during the call, the capacitance means C1. C1 is connected to the lines Tip and Ring so that the AC signal has a high impedance. As a result, a clear dial pulse without distortion can be transmitted.

[0008]

Embodiments of the power receiving circuit according to the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing the configuration of an embodiment of the power receiving circuit of the present invention, showing a configuration example of the power receiving circuit in the PCM communication device connected to the exchange 100 via a line (transmission line). In the figure, reference numeral 10 is a bias unit, 20 is a loop unit, 30 is a control unit, 40 is a ringback tone detection unit, 50 is a dial tone detection unit, and 100 is an exchange.

The bias unit 10 has resistors R1 and R2, a capacitor C1 and a switch SW1 and is connected to the tip side (Tip) and the ring side (Ring) of the line from the exchange 100. That is, in the bias detection unit 10, the resistor R1, the capacitor C1, and the switch SW1 are connected in series between one Tip and the other Ring of the line, and the resistor R1
To the terminal B of the loop section 20 from the common connection point between the capacitor C1 and the capacitor C1.
_The signal supplied to _IN is taken out.
The resistor R2 is connected between the common connection point of the resistor R1 and the capacitor C1 and the other ring of the line.

The loop section 20 allows most of the received power to flow, and the control section 30 controls the operation of the power receiving circuit.
Here, the transmission of the dial pulse is executed by the loop unit 20 performing an on / off operation in accordance with a control signal from the control unit 30. The voltage (DC voltage) between the lines Tip and Ring is divided by the resistors R1 and R2 in the bias unit 10, but is divided by the resistor R1 and the capacitor C1 with respect to the AC signal (voice signal). In other words, the capacity C1 is between the lines (Tip-Ring) of the power receiving circuit.
AC impedance (between) and AC signal (voice signal during call)
On the other hand, it is intended to look like high impedance. In other words, the loop unit 20 that flows most of the received current
Will appear as a high impedance to an AC signal due to the capacitance C1. Here, the line Tip-Ring
For the DC voltage in between, a voltage (bias voltage) of a predetermined potential divided by resistors R1 and R2 is supplied to the terminal B _IN of the loop unit 20.

The loop unit 20 sends a dial pulse to the line according to the control signal from the control unit 30 supplied to the terminal Lp _IN . Here, at the terminal RI of the control unit 30,
The output RIout of the ringback tone detection circuit 40 for detecting the ringback tone from the exchange 100 is supplied,
Further, the output Dout of the dial tone detection circuit 50 for detecting the dial tone from the exchange 100 is supplied to the terminal D of the control unit 30. Further, according to the control signal output from the terminal Dp of the control unit 30, the switch SW1
It is designed to control the on / off operation of the.

In the power receiving circuit of this embodiment, the switch S
W1 disconnects the capacity C1 when a dial pulse occurs, and connects the capacity C1 during a call to connect the lines Tip, R
The AC signal is controlled to have a high impedance with respect to ing. Here, the switch SW1
Although depicted as a relay, it goes without saying that other switching elements can be used.

First, in the power receiving circuit of this embodiment, when the switch SW1 is changed from on-hook to off-hook, the control section 30 cuts off (off-controls) the ring-back tone detection circuit 40 to detect the ring-back tone from the exchange. When the detection result is notified to the control unit 30, the control unit 30 switches on the switch SW1 (ON control). This operation will be described later in detail with reference to FIG.

Further, in the power receiving circuit of this embodiment, the switch SW1 is kept in the ON state when changing from on-hook to off-hook, the dial tone detection circuit 50 detects the dial tone from the exchange 100, and the result is When the control unit 30 is notified, the control unit 30 turns off the switch SW1, the ringback tone detection circuit 40 detects the ringback tone from the exchange, and the result is notified to the control unit 30. Then, the control unit 3
0 turns on the switch SW1.
This operation will be described later in detail with reference to FIG. 7.

FIG. 3 is a circuit diagram showing a configuration example of the power receiving circuit of the present invention, and specifically shows the configuration of the loop section in FIG. In FIG. 3, the switch SW
Unlike the embodiment shown in FIG. 2 in which 1 is composed of a relay, the switch SW1 is composed of a transistor TR2, and on / off control is directly performed according to a control signal from a terminal Dp of the control section 30.

As shown in FIG. 3, the loop portion 20 is
It includes resistors R3, R4, a transistor TR1, and a photocoupler PI1. The collector of the transistor TR1 is connected to one tip of the line, the emitter is connected to the other ring of the line through the resistor R3, and the base is connected to the output of the photocoupler PI1 (the emitter of the phototransistor). The input of the photocoupler PI1 (collector of the phototransistor) is the resistance R of the bias unit 10.
1 and the capacitor C1 are connected to a common connection point. In the photocoupler PI1, the terminal Lp of the control unit 30
The control signal from controls the light emission of the photodiode of the photocoupler PI1 connected to the power supply Va via the resistor R4. Further, the phototransistor of the photocoupler PI1 is controlled according to the light emission of the photodiode, and as a result, the on / off of the transistor TR1 is controlled. Then, the dial pulse is transmitted according to ON / OFF (switching) of the transistor TR1 in the loop unit 20.

FIG. 4 is a circuit diagram showing an example of a ringback tone detection circuit and a dial tone detection circuit in the power receiving circuit of the present invention, and FIG. 5 is a diagram showing frequency characteristics of the ringback tone and dial tone. .
As shown in FIG. 4, the ringback tone detection circuit 4
0 (dial tone detection circuit 50) is a differential amplifier 41 (5
1), bandpass filter 42 (52), and comparator 43 (53). Then, the ringback tone detection circuit 40 amplifies the ringback tone from the exchange 100 by the differential amplification section 41, and then extracts it by the bandpass filter 42. Here, the cutoff frequency of the bandpass filter 42 is fc ₂ = 1 / (2π · R5 · C2), fc ₃ =
1 / (2π · R5 · C3) [where fc ₂ <fc ₃ ].

Therefore, as shown in FIG. 5, by defining the cut-off frequencies fc ₂ and fc ₃ of the bandpass filter so as to pass the frequency (fo) of the ring back tone (dial tone), the ring The back tone (dial tone) can be retrieved. And
The output of the bandpass filter 42 is compared with the comparator 43.
If the ring back tone from the exchange 100 is detected,
A ringback tone detection signal is output to the terminal RI of the control unit 30. The configuration of the dial tone detection circuit 50 is similar, and when a dial tone from the exchange 100 is detected, a dial tone detection signal is output to the terminal D of the control unit 30.

FIG. 6 is a diagram showing a processing flow showing an example of the operation in the power receiving circuit of the present invention. As shown in FIG. 6, when the line is idle (Idle: step S11), the switch SW1 (transistor TR2) in the bias section 10 of the power receiving circuit is in the on state, and the transistor TR1 in the loop section 20 is in the off state (open state). Thus, no current is flowing in the power receiving circuit (step S21). At this time, the exchange 100 supplies power by applying ground level GND to one Tip side of the line and -48 V to the other Ring side of the line (step S31). In addition, exchange 10
Power supply by 0 is always performed.

Next, when the subscriber goes off-hook (Off Hook: Step S12), the switch SW1 of the power receiving circuit is turned on, the loop section 20 is closed (closed state), and a current flows through the power receiving circuit (Step S22). And exchange 100
Starts sending dial tone (step S3).
2). Further, when the subscriber starts to turn the dial (step S13), the loop section 20 of the power receiving circuit repeats open / close, and the dial pulse is transmitted (step S23). Here, the switch SW1 of the power receiving circuit remains in the off state (step S23). Then, the exchange 100 detects the dial pulse from the power receiving circuit transmitted through the line (step S33).

Then, when the subscriber finishes turning the dial (step S14), the loop portion 20 of the power receiving circuit is closed (step S24). At this time, the switch SW1 of the power receiving circuit remains off (step S2).
Four). When the exchange 100 starts transmitting the ringback tone (step S34), the ringback tone detection circuit 40 of the power receiving circuit detects the ringback tone and turns on the switch SW1 of the power receiving circuit (step S2).
Five). At this time, the loop section 20 of the power receiving circuit remains in the closed state (step S25). Also, the subscriber begins to hear a ringback tone (step S
15).

Further, the called party answers (step S3).
5), the switch SW1 of the power receiving circuit remains in the ON state, and the loop unit 20 remains in the closed state (step S26). Then, when the subscriber starts a call (step S16), and when the subscriber ends the call and goes on-hook (On Hook: step 17), the loop section 20 of the power receiving circuit is opened (step S27). At this time, the switch SW1 of the power receiving circuit remains in the ON state (step S27).

As described with reference to FIG. 6, in the power receiving circuit of this embodiment, the switch SW1 (transistor T1
R2) is cut off when changing from on-hook to off-hook, and is switched on when the ringback tone detection circuit 40 detects the ringback tone from the exchange. As a result, a clear dial pulse without distortion can be transmitted.

FIG. 7 is a diagram showing a processing flow showing another example of the operation in the power receiving circuit of the present invention. In the process flow shown in FIG. 7, step S22 in the process flow of FIG. 6 described above is removed, and steps S28 and S29 are inserted between steps S21 and S23. First, as shown in FIG. 7, when the line is idle (step S11), the bias unit 1 of the power receiving circuit 1
The switch SW1 (transistor TR2) in 0 is on, the transistor TR1 in the loop unit 20 is off (open), and no current flows in the power receiving circuit (step S21). At this time, the exchange 100 supplies power by applying ground level GND to one Tip side of the line and -48 V to the other Ring side of the line (step S31).

Next, the line idle state (step S1
From 1), when the subscriber goes off-hook (step S12), the loop portion 20 of the power receiving circuit is closed and current flows through the power receiving circuit (step S28). At this time, the switch SW1 of the power receiving circuit remains in the ON state (step S28). Further, the exchange 100 starts transmitting a dial tone (step S32).

Then, the dial tone detection circuit 50 of the power receiving circuit detects the dial tone from the exchange 100 and turns off the switch SW1 of the power receiving circuit (step S2).
9). Further, when the subscriber starts to turn the dial (step S13), the loop section 20 of the power receiving circuit repeats open / close, and the dial pulse is transmitted (step S23). Here, the switch SW1 of the power receiving circuit remains in the off state (step S23). Then, the exchange 100 detects the dial pulse from the power receiving circuit transmitted through the line (step S33).

Then, when the subscriber finishes turning the dial (step S14), the loop section 20 of the power receiving circuit is closed (step S24). At this time, the switch SW1 of the power receiving circuit remains off (step S2).
Four). When the exchange 100 starts transmitting the ringback tone (step S34), the ringback tone detection circuit 40 of the power receiving circuit detects the ringback tone and turns on the switch SW1 of the power receiving circuit (step S2).
Five). At this time, the loop section 20 of the power receiving circuit remains in the closed state (step S25). Also, the subscriber begins to hear a ringback tone (step S
15).

Further, the called party answers (step S3).
5), the switch SW1 of the power receiving circuit remains in the ON state, and the loop unit 20 remains in the closed state (step S26). Then, when the subscriber starts a call (step S16), and when the subscriber ends the call and goes on-hook (On Hook: step 17), the loop section 20 of the power receiving circuit is opened (step S27). At this time, the switch SW1 of the power receiving circuit remains in the ON state (step S27).

Here, the processing after step S13 is as shown in FIG.
It is the same as the processing flow of. As described with reference to FIG. 7, in the power receiving circuit of the present embodiment, the switch SW1
The (transistor TR2) is kept in the ON state when changing from on-hook to off-hook, and is cut off when the dial tone detection circuit 50 detects the dial tone from the exchange 100, and the ringback tone detection circuit 40 is further disconnected from the exchange. When a ringback tone is detected, it will be switched on. As a result, a clear dial pulse without distortion can be transmitted.

FIG. 8 is a diagram showing an example of a line to which the power receiving circuit of the present invention is applied, and FIG. 9 is a diagram showing another example of a line to which the power receiving circuit of the present invention is applied. As shown in FIG. 8, the power receiving circuit of the present invention is used as a power receiving circuit of a COT (Central Office Terminal) station.
COT connected to switch 100 via line (Tip, Ring)
The station is an RT (remote terminal) via a PCM line.
The RT station is connected to each subscriber via a line (Tip, Ring). Further, in the example of FIG. 9, as a subscriber connected to the RT station, PBX (Privat)
e Branch Exchange: Private branch exchange.

In the above description, the operation of the power receiving circuit of the present invention is during the dial line service.
When the power receiving circuit of the present invention is applied to the touch-tone telephone line, the control unit 30 controls so that the switch SW1 (transistor TR2) is always kept in the ON state.

[0032]

As described above in detail, according to the power receiving circuit of the present invention, by disconnecting the capacitance when the dial pulse is generated by the loop portion, a clear dial pulse without distortion can be transmitted.

[Brief description of drawings]

FIG. 1 is a block diagram showing a principle configuration of a power receiving circuit according to the present invention.

FIG. 2 is a block diagram showing a configuration of an embodiment of a power receiving circuit of the present invention.

FIG. 3 is a circuit diagram showing a configuration example of a power receiving circuit of the present invention.

FIG. 4 is a circuit diagram showing an example of a ringback tone detection circuit and a dial tone detection circuit in the power receiving circuit of the present invention.

FIG. 5 is a diagram showing frequency characteristics of a ring back tone and a dial tone.

FIG. 6 is a diagram showing a processing flow showing an example of an operation in the power receiving circuit of the present invention.

FIG. 7 is a diagram showing a processing flow showing another example of the operation in the power receiving circuit of the present invention.

FIG. 8 is a diagram showing an example of a line to which the power receiving circuit of the present invention is applied.

FIG. 9 is a diagram showing another example of a line to which the power receiving circuit of the present invention is applied.

FIG. 10 is a block diagram showing a configuration of an example of a conventional power receiving circuit.

[Explanation of symbols]

 10 ... Bias part 20 ... Loop part 30 ... Control part 40 ... Ring back tone detection circuit 50 ... Dial tone detection circuit 100 ... Exchange R1, R2, R3 ... Resistor means (resistor) TR1 ... Transistor PI1 ... Photo coupler SW1 ... Switch means ( Switch) Va, Vt, Vr ... Power supply means

Claims (7)

[Claims] 1. A bias section (10) having a first resistance means (R1) and a capacitance means (C1) connected in series between one side (Tip) and the other side (Ring) of a line, and the line. Loop part (20) that sends dial pulse to
A control unit (30) for controlling the loop unit, and a switch unit (SW1) for controlling disconnection of the capacity unit (C1) with respect to the line (Tip, Ring). Power receiving circuit. 2. The bias section (10) comprises the capacitance means (C1) and the switch means (S) connected in series.
W1) to the second resistance means (R
The power receiving circuit according to claim 1, further comprising 2). 3. The switch means (SW1) is connected in series to the capacitance means (C1), disconnects the capacitance means (C1) when the loop section (20) sends a dial pulse, and at the time of a call. 2. The power receiving circuit according to claim 1, wherein the capacitance means (C1) is connected to the line (Tip, Ring) so that the AC signal has a high impedance. 4. The power receiving circuit further detects the dial tone from the exchange to detect the switch means (SW1).
2. The power receiving circuit according to claim 1, further comprising a dial tone detection circuit (40) for turning off the switch. 5. The power receiving circuit further detects a ring back tone from the exchange to detect the switch means (SW).
Ring back tone detection circuit (5)
0) is included in the power receiving circuit according to claim 1. 6. The power receiving circuit according to claim 1, wherein the switch means (SW1) is on-controlled when changing from on-hook to off-hook and when dial pulse is transmitted. 7. The power receiving circuit according to claim 4, wherein switching control of the switch means (SW1) is performed via the control unit (30).