JP2869298B2 - External telephone ringer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external telephone ringing device connected to an answering machine, a facsimile machine, a TEL / FAX switching device, and the like.

[0002]

2. Description of the Related Art Conventionally, an external telephone is connected to an answering machine, a facsimile apparatus, a TEL / FAX switching apparatus, and the like, and the external telephone is caused to ring by an external telephone ringing device built in the main body of the apparatus. I have to.
In this case, the external telephone ringing device rings the external telephone using the ringing signal generated by the device body without using the ringing signal transmitted from the telephone line.

FIG. 2 is a circuit diagram of a conventional external telephone ringing device. In the figure, R is a discharge resistor, which is connected to a capacitor and a ringer circuit built in an external telephone (not shown). The capacitor is provided to cut off the DC component of the sound signal sent to the ringer circuit, and the charge charged in the capacitor flows through the discharge resistor R and is discharged. Here, a resistor having a large resistance value is used as the discharge resistor R in order to reduce power consumption due to discharge.

[0004] A DC power supply unit 11 generates a power supply voltage to generate a ringing signal to be sent to a ringer circuit of the external telephone. Normally, in analog telephone lines, 75 [V _rms ] is applied to a DC voltage of -48 [V].
Are superimposed to generate a sine-wave ringing signal. Therefore, in order to match the ringing signal of the external telephone ringing device with the ringing signal of the analog telephone line, the DC power supply unit 11 generates a power supply voltage of -180 [V] and a power supply voltage of +24 [V]. I have. Therefore, the DC power supply unit 11
It has a power supply circuit for generating a power supply voltage of 80 [V] and a power supply circuit for generating a power supply voltage of +24 [V].

A switch (SW) circuit 12 receives a control signal MEI generated by a signal generator (not shown) of the apparatus main body and turns on and off a power supply voltage of -180 [V] of the DC power supply unit 11. It is. Then, the power supply voltage of -180 [V] turned on / off by the switch circuit 12 and the power supply voltage of +24 [V] of the DC power supply unit 11 are sent to the voltage synthesizing circuit 13. Synthesizes them to generate a sound signal of a rectangular wave, and sends the sound signal to the ringer circuit of the external telephone.

[0006]

However, in the conventional external telephone ringing device, a power supply circuit for generating a negative power supply voltage and a power supply circuit for generating a positive power supply voltage are provided in the DC power supply unit 11. In addition, since the power supply voltage of the negative electrode and the power supply voltage of the positive electrode need to be combined by the voltage combining circuit 13, the structure becomes complicated and the cost increases.

Further, the external telephone ringing device needs to have a simplified structure so that it can be built into the device body. Therefore, it is necessary to configure a simple oscillating circuit, and in that case, the generated sound signal becomes a rectangular wave. When a 600-series telephone is used as an external telephone, the external telephone can be sounded by a sound signal of a rectangular wave. However, when an electronic telephone is used as the external telephone, a resonance prevention circuit is built-in. In some cases, the sound cannot be sounded.

That is, an electronic telephone having a built-in resonance prevention circuit can prevent another telephone connected in branch from ringing by a dial pulse when dialing by one telephone. ing. In this case, the resonance prevention circuit distinguishes a ringing signal consisting of a normal sine wave and a dial pulse consisting of a rectangular wave by waveforms. Therefore, even when a ringing signal composed of a rectangular wave is sent to the external telephone in the same manner as the dial pulse, the resonance prevention circuit operates, so that the external telephone cannot be sounded sufficiently.

Further, since a large resistance value is used for the discharge resistor, the discharge time of the capacitor of the external telephone becomes long. Therefore, when an external telephone having a large capacitance is used or a large number of external telephones are connected in parallel, sufficient discharge is not performed and the external telephone cannot be sounded. The present invention solves the problems of the conventional external telephone ringing device,
The structure can be simplified, the cost can be reduced, and even if an external telephone with a built-in resonance prevention circuit, an external telephone with a large capacitance, or a large number of external telephones connected in parallel is used. An object of the present invention is to provide an external telephone ringing device capable of sufficiently ringing.

[0010]

For this purpose, in the external telephone ringing apparatus of the present invention, a line connected to a capacitor of the external telephone and two lines connected to the line via switch means, respectively. And two means for alternately turning on and off the switch means.

A discharge resistor connected to the line and used only when a lower power supply voltage of the two power supply circuits is supplied to the line to discharge the capacitor, and a resistance value of the discharge resistor. Means for changing.

[0012]

According to the present invention, as described above, the external telephone ringing device comprises: a line connected to a capacitor of the external telephone;
The power supply circuit includes two power supply circuits connected to the lines via switch means for supplying two positive power supply voltages, and means for alternately turning on and off the switch means.

When the switch is turned on and off alternately, a ringing signal consisting of two positive voltages is generated.
In this case, since a positive power supply voltage is always supplied to the line, when the handset is off-hook while the external telephone is ringing, it is possible to detect that a DC loop has been formed. A discharge resistor connected to the line and used only when a lower power supply voltage of the two power supply circuits is supplied to the line to discharge the capacitor; and a means for changing a resistance value of the discharge resistor. And

Therefore, the waveform of the sound signal can be set by changing the resistance value of the discharge resistor.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a main part circuit diagram of an external telephone ringing device showing an embodiment of the present invention, FIG. 3 is a diagram showing a first operation table of an external telephone ringing device showing an embodiment of the present invention, and FIG. FIG. 5 is a diagram showing a second operation table of the external telephone ringing device according to the embodiment of the present invention, FIG. 5 is a waveform diagram of control signals and selection signals of the external telephone ringing device according to the embodiment of the present invention, and FIG. It is a waveform diagram of a ringing signal of an external telephone ringing device showing an embodiment of the present invention.

In FIG. 1, A is a line connected to a capacitor and a ringer circuit built in an external telephone (not shown), and a ringing signal is sent to the ringer circuit via the line A. Further, the capacitor is provided to cut a direct current component of a sound signal sent to the ringer circuit. Tr1 is a transistor for applying a power supply voltage of +180 [V] to the ringer circuit, and Tr2 is +2
A transistor for applying a power supply voltage of 4 [V] to the ringer circuit, R1 is a first discharge resistor, and R2 is a second discharge resistor. And the electric charge charged in the capacitor is:
The current flows selectively to the first and second discharge resistors R1 and R2 to be discharged.

The emitter of the transistor Tr1 is connected via a resistor R3 to +180
[V] is connected to the power supply circuit, and the collector is connected to the line A. The emitter of the transistor Tr2 is connected to a +24 V power supply circuit of the DC power supply unit via a resistor R4, and the collector is connected to the line A via a diode D1.

Then, the transistor Tr1 is turned on.
To turn off, the base of the transistor Tr1 is grounded via the resistor R5 and the transistor Tr3. In order to turn on / off the transistor Tr2, the base of the transistor Tr2 is grounded via the resistor R6 and the transistor Tr4. The control signal ME is connected to the base of the transistor Tr3 via the resistor R7.
I is input, and the control signal MEI is input to the base of the transistor Tr4 via the resistor R8 and the inverter INV.

In this case, the control signal MEI is generated by a signal generator (not shown) of the apparatus main body. In addition, a connection between the connection portion of the line A to the diode D1 and the external telephone is grounded via the first discharge resistor R1 and the transistor Tr5, and a connection between the connection portion and the transistor Tr1 is the second discharge resistor R2. And the transistor Tr6.

Then, the transistor Tr5 is turned on.
To turn off, the base of the transistor Tr5 is grounded via the resistor R9 and the transistor Tr7, and to turn on / off the transistor Tr6, the base of the transistor Tr6 is grounded via the resistor R10 and the transistor Tr8. Further, in order to turn on / off the transistor Tr7, the base of the transistor Tr7 is connected to the AND circuit AND1 via the resistor R11,
To turn on / off the transistor Tr8, the base of the transistor Tr8 is connected to the AND circuit AND2 via the resistor R12.

The selection signal SEL2 is input to one input terminal of the AND circuit AND1, the output of the inverter INV is input to the other terminal, and the selection signal SEL1 is input to one input terminal of the AND circuit AND2 and the other input terminal. The output of the inverter INV is input to the terminal of. When the control signal MEI and the selection signals SEL1 and SEL2 are set to the high level (H) or the low level (L) as shown in FIGS. A ringing signal is generated. Therefore, the external telephone can be sounded by sending the ringing signal to the ringer circuit of the external telephone.

That is, when the control signal MEI is at a low level, the output of the inverter INV goes to a high level, turning on the transistor Tr4 and turning on the transistor Tr2. Therefore, a power supply voltage of +24 [V] is supplied to the line A. The control signal ME
When I is at the low level, the transistor Tr3 is turned off, so that the transistor Tr1 is also turned off. Therefore, the power supply voltage of +180 [V] is not supplied to the line A.

On the other hand, when the control signal MEI is at the high level, the output of the inverter INV goes to the low level, the transistor Tr4 is turned off, and the transistor Tr4 is turned off.
2 turns off. Therefore, the power supply voltage of +24 [V] is not supplied to the line A. Further, when the control signal MEI is at a high level, the transistor Tr3 is turned on, so that the transistor Tr1 is also turned on. Therefore, +
A power supply voltage of 180 [V] is supplied to the line A.

By repeating this operation at a cycle of 16 to 25 [Hz], power supply voltages of +180 [V] and +24 [V] are alternately supplied to the line A, and the power supply voltage of +180 [V] as shown in FIG. A ringing signal having a waveform obtained by repeating a voltage of +24 [V] is generated. The frequency of the ringing signal can be changed by the switching frequency of the control signal MEI. The voltage of the ringing signal is +18
It becomes 0 [V] and becomes +24 [V] when it is off. In this case, since a voltage of +24 [V] or more is always supplied to the line A, if a handset (not shown) is off-hook while the external telephone is ringing, it is detected that a DC loop has been formed. it can.

In this embodiment, the first and second discharge resistors R
1, R2 are used only when the power supply voltage of +180 [V] is not supplied to the line A. Therefore, a signal obtained by inverting the control signal MEI by the inverter INV is input to the AND circuits AND1 and AND2, and only when the control signal MEI is off, the transistor Tr7 or Tr8 is turned on and the transistor Tr5 or Tr6 is turned on. Is done.

The first and second discharge resistors R1,
R2 is connected to the capacitor of the external telephone, and the waveform of the ringing signal can be set by changing the resistance values of the first and second discharge resistors R1 and R2. Therefore, the first and second discharge resistors R1 and R2 have different resistance values, and either the first discharge resistor R1 is used or the second discharge resistor R1 is used.
2 is selected by the selection signals SEL1 and SEL2. In this embodiment, when the selection signal SEL1 is at a high level, the second discharge resistor R2
Is used, and when the selection signal SEL2 is at a high level, the first discharge resistor R1 is used.

When the control signal MEI is at a high level, the transistor Tr3 is turned on and the transistor Tr1 is turned on. Since the output of the inverter INV is at a low level, the transistor Tr4 is turned off and the transistor Tr2 is turned off. Turns off. At this time, a power supply voltage of +180 [V] is supplied to the line A. Further, since the transistors Tr7 and Tr8 are turned off and the transistors Tr5 and Tr6 are also turned off, the first and second discharge resistors R1 and R2 are not used.

When the control signal MEI is at a low level, the transistor Tr3 is turned off and the transistor Tr1 is turned off. Since the output of the inverter INV is at a high level, the transistor Tr4 is turned on and the transistor Tr2 is turned on. Turns on. At this time, a power supply voltage of +24 [V] is supplied to the line A.
Further, since the transistors Tr7 and Tr8 are turned on and the transistors Tr5 and Tr6 are also turned on, the first and second discharge resistors R1 and R2 are used.

As described above, the first and second discharge resistors R1, R
Since it is no longer necessary to use the first and second discharge resistors R1, R2, it is possible to use first and second discharge resistors R1 and R2 having a small resistance value, thereby reducing power consumption and shortening the discharge time. be able to. When an electronic telephone having a built-in resonance prevention circuit is used as an external telephone, the electronic telephone does not ring even if a ringing signal composed of a rectangular wave as shown in FIG. 6 is sent to the external telephone.

In order to use an external telephone having a built-in resonance prevention circuit as an external telephone, use the larger one of the first and second discharge resistors R1 and R2, and set the discharge time for ringing. I try to make it longer. By doing so, the rectangular wave can be smoothed, and the external telephone can be sounded sufficiently. When an external telephone having a large capacitance is used or a large number of external telephones are connected in parallel, the smaller one of the first and second discharge resistors R1 and R2 is used. Then, sufficient discharge can be performed, and the external telephone can be sounded.

The present invention is not limited to the above embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0032]

As described above in detail, according to the present invention, the external telephone ringing device comprises a line connected to the capacitor of the external telephone, and a line connected to the line via the switch means. It has two power supply circuits for supplying two positive power supply voltages, and means for alternately turning on and off the switch means.

When the switch is turned on and off alternately, a ringing signal consisting of two positive voltages is generated.
In this case, since a positive power supply voltage is always supplied to the line, when the handset is off-hook while the external telephone is ringing, it is possible to detect that a DC loop has been formed. A discharge resistor connected to the line and used only when a lower power supply voltage of the two power supply circuits is supplied to the line to discharge the capacitor; and a means for changing a resistance value of the discharge resistor. And

Therefore, since it is not necessary to always use a discharge resistor, it is possible to use a discharge resistor having a small resistance value, thereby reducing power consumption and shortening a discharge time. . Also,
The waveform of the sound signal can be set by changing the resistance value of the discharge resistor. Therefore, when using an electronic telephone with a built-in resonance prevention circuit as an external telephone, it is necessary to increase the resistance value of the discharge resistor to lengthen the discharge time when ringing, and to smooth the rectangular wave. Thus, the external telephone can be sufficiently sounded.

When an external telephone having a large capacitance is used or a large number of external telephones are connected in parallel, a sufficient discharge is performed by reducing the resistance value of the discharge resistor. And the external telephone can be sounded.

[Brief description of the drawings]

FIG. 1 is a main part circuit diagram of an external telephone ringing device showing an embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional external telephone ringing device.

FIG. 3 is a diagram illustrating a first example of an external telephone ringing device according to an embodiment of the present invention.
FIG. 4 is a diagram showing an operation table of FIG.

FIG. 4 shows a second embodiment of the external telephone ringing device according to the embodiment of the present invention.
FIG. 4 is a diagram showing an operation table of FIG.

FIG. 5 is a waveform diagram of a control signal and a selection signal of the external telephone ringing device according to the embodiment of the present invention.

FIG. 6 is a waveform diagram of a ringing signal of the external telephone ringing device according to the embodiment of the present invention.

[Explanation of symbols]

 A line R1 First discharge resistor R2 Second discharge resistor R3 to R12 Resistance Tr1 to Tr12 Transistor SEL1, SEL2 selection signal AND1, AND2 AND circuit INV inverter MEI control signal

Claims (1)

(57) [Claims] (A) a line connected to a capacitor of an external telephone, (b) two power supply circuits connected to the line via switch means and supplying two positive power supply voltages, (C) means for alternately turning on and off the switch means; and (d) the capacitor which is connected to the line and which is used only when the lower power supply voltage of the two power supply circuits is supplied to the line. And (e) means for changing the resistance value of the discharge resistor.