JPH0332129Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a bidirectional voltage booster circuit for telephone terminal equipment, which applies local DC power supply voltage in series to telephone terminal equipment such as PBX and button telephone equipment. be.

[Conventional technology]

Telephone terminal devices such as PBX and key telephone devices are
Since it operates by being connected to the terminal of the office line, even if the office line has the maximum resistance specified by the equipment standards,
The station equipment and the connected terminal equipment must operate normally. For this reason, a certain tolerance value is prescribed for the resistance value of the terminal device. However, the terminal device includes an office line control circuit, a switching circuit that selects and connects an extension telephone to the office line, an extension control circuit, and the like, as well as an extension line that connects the extension telephone. As a result, the DC resistance value of these terminal devices may become larger than the specified tolerance value. When such a device is connected to an arbitrary central office line, there may be a case where the direct current for communication is insufficient or the device is unable to function normally. For this reason, when this terminal device is applied, it is restricted to the office line whose resistance value is less than a limited value, and it cannot be called a general-purpose product.

[The problem that the idea aims to solve]

Conventionally, when the DC resistance value of a designed terminal device exceeds a predetermined value, some measures have been taken to reduce the DC resistance, such as omitting part of the circuit function and redesigning it, or limiting the length of the extension line to the extension telephone. There was a problem that required measures to be taken to reduce this.

As a countermeasure to this problem, it is impossible to increase the amount of current by increasing the power supply voltage of the station equipment, since this would have a large effect on other lines as well.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an additional circuit for increasing the communication path current supplied to a telephone terminal.

[Means and actions for solving problems]

In order to achieve this purpose, this invention uses PBX
Alternatively, a detection circuit that is inserted in a line between a central office line side device such as a button telephone device and an extension line side device and detects the direction of communication line current flowing in this line, and a one-way conduction element and a 1, a unidirectional conduction element control circuit having a second switching circuit, and a first and a second pressure intensifier circuit having the same configuration; When it is detected that the conduction direction of the communication path current is the same as the conduction direction of the one-way conduction element, the one-way conduction element conducts the communication path current. With,
The first switching circuit connects a local DC power supply voltage having the same direction polarity as the conduction direction of the one-way conduction element to the one-way conduction element in parallel, and the first switching circuit connects a local DC power supply voltage having the same direction polarity as the conduction direction of the one-way conduction element, and also connects a local DC power supply voltage having the same direction polarity as the conduction direction of the one-way conduction element. The second switching circuit short-circuits this one-way conduction element when it is detected that there is no current in the communication path or in a direction opposite to the direction of conduction.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In the drawing, CO is the office line and the office line control circuit.
Connect to terminals A1 and B1 of COT. Terminal A101 of the first booster circuit NR1, details of which will be described later, is connected to terminal A2 of the station line control circuit COT, and its output terminal A102 is connected to terminal A2 of the second booster circuit NR2.
02 and terminal A2 of the second booster circuit NR2.
01 is the terminal A of the switching device and extension control circuit (hereinafter referred to as extension control circuit) SW, SUB
Connect to 3. In addition, terminal B2 is an extension control circuit.
Connect to SW, SUB terminal B3.

Extension control circuit SW, SUB terminals A41, B41
...A4n and B4n have extension line resistances R11 and R.
12...Extension telephone T1... via Rn1 and Rn2...
…Tn is connected.

CONT is a control circuit; station line control circuit COT, extension line control circuit SW, SUB, booster circuit NR1, NR2
It sends and receives information to and from these circuits, and controls these circuits.

B is a local DC power supply with polarities of −, 0, and +;
A predetermined value is selected and used for the voltage based on the resistance values of the office line and the terminal device.

The drawing shows a case where the general subscriber telephone line to which the terminal device is connected is in a normal state, and the polarities of terminals A2 and B2 are - and +, and in the following description,
The current flowing in the communication path indicates that the direction of the communication path current in this state is the opposite direction, and the terminals A2 and B2
The polarity of is reversed to + and -, and the direction of the communication path current during the communication state is indicated as a constant direction.

In the device configured as described above, the polarity of terminals A2 and B2 is changed when the extension telephone T1 is on-hook, when the extension telephone T1 lifts up the handset to make a call, and from the central office line CO. When a call is received, the polarity is normal -, +, and the current direction in the communication path is opposite.

However, when the other party answers the outgoing call from the extension telephone T1, the polarity of the office line CO is reversed, and when the extension telephone T1 answers the incoming call, the control circuit CONT controls the office line control circuit COT. Since the polarity is reversed, the polarity of terminals A2 and B2 is + and -
to be reversed.

Next, the configurations of the first and second booster circuits NR1 and NR2 will be explained. Both circuits NR1 and NR2 are
Although they have the same configuration, even though the polarities of terminals A2 and B2 are the same, the direction of the communication path current flowing through the detection circuit and the one-way conduction element is opposite, so each circuit is connected to the direction of the respective communication path current. Perform the corresponding action. Therefore, the explanation will focus on circuit NR1, and for the convenience of explanation, the circuit NR2 will be referred to as the circuit NR2.
Elements corresponding to the 100s of NR1 are numbered in the 200s.

The first booster circuit NR1 includes a detection circuit that detects the communication path current direction and a one-way conduction element control circuit CNT1 that controls the one-way conduction element.

The detection circuit is a circuit that conducts communication path current.
The one-way conduction element control circuit CNT1, which will be described later, is turned on when a communication path current is detected in the base-emitter direction, that is, in a certain direction.
a transistor 101 for starting the transistor 101; and a resistor 102 connected in parallel between the base and emitter for stably operating the transistor 101.
and a phototransistor that conducts a communication path current in the opposite direction. transistor 10
The base of 1 is connected to terminal A2 on the office line side, and the emitter is a diode 10 which is a one-way conduction element described later.
Further, the collector is connected to the + pole of the local power supply B via resistors 105 and 104 connected in series.

When the transistor 106 of the control circuit CNT1 is turned on as a one-way conduction element, one of the collector outputs is connected to the resistor 107, the starting resistor 10 of the transistor 109 which is the first switching circuit.
The transistor 109 is operated in the circuit connected to the negative pole of the local power supply B through the diode 103.
Connect local power supply B in parallel to . In addition, the other output is connected to the diode 112 and the resistors 113 and 114.
The second circuit is connected to the negative pole of local power supply B through
The operation of the transistor 111, which is a switching circuit, is suppressed to prevent the one-way conduction element from being short-circuited. Therefore, the resistance values of the resistors 113 and 114 are set so that the voltage value generated across the resistor 114 when the circuit is energized is higher than the voltage at the 0, - pole of the local power supply B.

As mentioned above, the transistor 109 operates when a channel current in a certain direction is detected, and connects the - and 0 poles of the local power supply B in parallel to the anode and cathode of the diode 103, and its emitter is connected to the local power source B. The collector is diode 1 on the negative pole of power supply B.
Connect to the anode side of 03.

Here, if the reverse withstand voltage of the diode 103 is set higher than the voltage value of the − and 0 poles of the parallel-connected local power supplies B, the communication path current is increased by the parallel-connected local power supply voltage.

Transistor 111 operates when the direction of the channel current is in the opposite direction and is in a normal state, that is, when transistors 101 and 106 are off, and short-circuits diode 103 so that there is no problem in passing the channel current. It is turned on by the current flowing through the circuit from the 0 pole of the local power supply B to the terminal A102 to the emitter/base of the transistor 111 to the resistor 114 to the negative pole of the local power supply B, and the diode 103
is short-circuited by the collector connected to its anode side and the emitter connected to its cathode side.

Note that even when the transistor 106 is on, the operating circuit of the transistor 111 is formed; in this case, the transistor 106
As explained above, since the base of the transistor 111 has positive polarity with respect to the emitter, the transistor 111 will not be turned on and the diode 103 will not be shorted.

The resistor 113 is for setting the voltage generated at the terminal of the resistor 114, and the resistor 107 is for setting the voltage generated at the terminal of the resistor 114.
This is for limiting the collector current of No. 6. diode 11
2 is for preventing the current of the circuit from the 0th station of the local power supply B to the emitter/base of the transistor 111 to the resistor 114 to the negative pole of the local power supply B from flowing into the resistor 107. capacitor 110
is connected in parallel to the diode 103 to form an auxiliary path for the audio signal current during a call and to stabilize the alternating current characteristics of the diode 103.

Next, the operation of the above embodiment will be explained.

(1) When the device is not on a call and has reverse current.

In this case, the terminal A2 has the normal polarity -.
In circuit NR1, this channel current flows in the opposite direction through the phototransistor and transistor 101 is not turned on. Therefore, transistors 106 and 109 do not operate, and diode 10
The voltage of local power supply B is not applied in parallel to both terminals of 3. On the other hand, the transistor 111 is turned on by the current flowing from the 0,- terminal of the local power supply B through its emitter-base, the diode 103 is shorted, and the communication path current flows through the transistor 111.

On the other hand, in circuit NR2, the direction of this communication path current is opposite to circuit NR1 and displays a constant direction, so it operates in the same way as circuit NR1 in section (2) below, and the detection circuit and unidirectional conduction element control circuit
CNT2 operates to turn on transistor 209 and apply the voltage of local power supply B to diode 203 in parallel. Therefore, the communication path current increases by this applied voltage.

The phototransistor also reports this state to the control circuit CONT.

(2) When the device is on a call and the current is in a constant direction.

In this case, the terminal A2 is determined to have positive polarity. In circuit NR1, transistor 101
A communication path current flows in a fixed direction through the base and emitter of the diode 103. Therefore, transistor 101 detects that the communication path current is in a fixed direction and turns on, and transistor 106 also turns on. This operation energizes resistors 107 and 108 and turns on transistor 109. As a result, the anode and cathode of the diode 103 are connected to the cathode terminal A102 of the diode 103.
- 0 pole of power supply B - - pole of power supply B - Transistor 1
In the emitter-collector diode 103 anode circuit 09, - and 0 polarity voltages of the local power supply B are applied in parallel. In this case, diode 1
Since the reverse withstand voltage of 03 is set higher than the voltage value of the 0 and - poles of power supply B, the voltage on the communication path is increased by the applied local power supply voltage.

On the other hand, in circuit NR2, the direction of this communication path current is opposite to that in circuit NR1, and the opposite direction is displayed.
The same operation as the circuit NR1 described in the previous section (1) is performed. That is, the communication path current flows through the phototransistor, transistors 201, 206, and 209 are not turned on, and only transistor 211 is turned on, shorting diode 203.

If we look at this from the perspective of terminals A2 and B2, no matter which direction the communication path current flows within the device, the effect is equivalent to increasing the power supply voltage of the station equipment by the amount that the local power supply voltage is applied. occurs, the communication current increases to the specified value, and each device can operate normally.

As explained above, the elements used in this circuit, such as transistors and diodes, are used in a saturated state, so their impedance is equivalent to a minute pure resistance. Since the resistor transistors and the like are connected in parallel, the operation is equivalent to simply inserting a local power supply in series with the subscriber telephone line. In addition, because the voltage value of the local power supply is selected based on the total resistance value of the subscriber telephone line to which the terminal device is fixedly connected on a one-to-one basis and this device, excessive current may occur in the subscriber telephone line. do not have. Therefore, the impedance value of the subscriber telephone line does not affect the output of this circuit, and conversely, the insertion of this circuit does not change the impedance of the line.

Since the line is inserted only into one line, there is a risk of unbalance occurring in the line, but the AC impedance is equivalently a pure resistance of minute value, and the Therefore, there will be no imbalance in the line.

Although the local DC power source B has been described using a battery as an example, a DC output rectified from a commercial AC power source, a solar cell, a switching power source, or the like may also be used.

[Effect of idea]

As explained above, according to the present invention, a DC voltage is inserted in series to the subscriber telephone line regardless of the direction of the current in the communication path, so that from the office line terminal to the extension telephone Even if the resistance value of the device is higher than the specified value, the current value can be increased to the specified value. Therefore, in telephone terminal equipment such as PBX or button telephone equipment, it is possible to easily solve the technical difficulty required to change the circuit to reduce the direct current resistance value of the central office line control circuit, etc. There is also the advantage that the line length between the extension telephone and the telephone can be increased.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing an embodiment of the present invention. CO is the office line, COT is the office line control circuit, NR1, NR
2 is a first and second booster circuit, CNT1 and CNT2 are one-way conduction element control circuits, SW and SUB are switching devices and extension control circuits, T1...Tn are extension telephones, and CONT is a control circuit.

Claims (1)

[Scope of utility model registration request] A detection circuit that is inserted in a line between a central office line side device such as a PBX or a button telephone device and an extension line side device and detects the direction of communication line current flowing in this line, a one-way conduction element, and It is composed of first and second booster circuits having the same configuration, each consisting of a one-way conduction element control circuit having first and second switching circuits, and both pressure booster circuits have the one-way conduction element in opposite directions. When it is detected that the direction of conduction of the communication path current is the same as the direction of conduction of the one-way conduction element, the one-way conduction element conducts the communication path current. At the same time, the first switching circuit connects a local DC power supply voltage having the same direction polarity as the conduction direction of the one-way conduction element to the one-way conduction element, and
When it is detected that the direction of conduction of the communication path current is opposite to the direction of conduction of the one-way conduction element or that there is no communication path current, the second switching circuit short-circuits the one-way conduction element. A bidirectional voltage booster circuit for a telephone terminal device, characterized in that: