JPH0846714A - Communication equipment - Google Patents

Abstract

PURPOSE:To prevent occurrence of spike noise in the transient state. CONSTITUTION:The equipment is provided with a transistor circuit 10 provided in a telephone communication circuit 3 connecting to a telephone line and bypassing a base current with a capacitor C1 so as to separately set a DC resistor and an AC resistor to separate a DC from an AC and also with promotion means C3, 11 promoting DC current of the telephone communication circuit 3 to reach a rated current quickly for the transient period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device for preventing spike noise from being generated in a telephone communication circuit or a facsimile line control circuit connected to a telephone line.

[0002]

2. Description of the Related Art Facsimile machines have a telephone communication circuit for transmitting voice and a facsimile line control circuit for transmitting images, which are connected to a telephone line so that they can be switched to each other. FIG. 9 is a diagram showing an example of such a circuit. The facsimile line control circuit 1 is connected to the telephone line terminals L1 and L2, and the facsimile line control circuit 1 is connected to C.
The telephone communication circuit 3 is connected via the ML relay 2.
The facsimile line control circuit 1 is connected to a modem by a transformer 4 and a calling circuit 5 for dialing in the circuit.
Is provided. In the telephone communication circuit 3, when connecting the telephone to the telephone line, the diode bridge 6 for preventing the positive and negative of the power source from being reversed regardless of the polarity of the connection, the hook switch 8 for opening and closing the circuit by the handset 7, the telephone A speech circuit 9 for communication is provided.

The speech circuit 9 is provided with a DC / AC impedance adjusting circuit 10. The telephone communication circuit 3 is provided for this purpose by connecting a circuit for setting the resistance seen in terms of direct current and the resistance seen in terms of alternating current to predetermined values respectively. FIG. 10 shows an example of a DC / AC impedance adjustment circuit. Transistor T
The r has an AC resistor R1 between the collector and the base, a DC resistor R2 between the emitter and the ground, and a bypass capacitor C1 between the base and the ground. When the bypass capacitor C1 is charged and the base voltage reaches a predetermined value, the emitter current flows through the transistor Tr and the DC resistance becomes R2. However, while the bypass capacitor C1 does not charge to the predetermined base voltage, the transistor Tr
The DC resistance is infinite when it is open in terms of DC. The AC resistance is R1 regardless of charging.
Becomes In this way, the direct-current resistance reaches the predetermined value R2 after the bypass capacitor C1 is charged.

[0004]

FIG. 11 is a diagram showing changes in the voltage between the terminals L1 and L2 in FIG. First, when the handset 7 of the telephone communication circuit 3 is removed, in the DC / AC impedance adjusting circuit 10, the DC resistance value decreases as the bypass capacitor C1 is charged, and becomes the specified R2. Therefore, when OFF HOOK is performed, the terminals L1 and L2 are
The voltage between them drops gently as shown in the figure, and the DC resistance (R2
And a resistance that is connected in series or in parallel in the telephone communication circuit 3). When the CML relay 2 is turned on, the telephone communication circuit 3 is disconnected and the resistance of the transformer 4 of the facsimile line control circuit 1 becomes the resistance. In this case, the switches of the CML relay 2 and the calling circuit 5 are initially interlocked and turned on. When the CML relay 2 is turned off after calling the calling circuit 5, the telephone communication circuit 3 receives the terminals L1 and L2.
Although a voltage is applied between them and the hook switch 8 is turned on, the bypass capacitor C1 is not charged, so that the circuit is in an open state and spike noise is generated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a communication device which prevents the generation of spike noise even during a transitional period such as relay OFF.

[0006]

In order to achieve the above object, in the invention of claim 1, a telephone communication circuit connected to a telephone line and a direct current provided in the telephone communication circuit for closing the line are provided. A direct current resistance of the telephone communication circuit and a transistor circuit in which the direct current resistance for separating the alternating current forming the signal and the alternating current resistance can be set separately by bypassing the base current with the first capacitor It is provided with a facilitating means for promptly approaching the rated value during the period.

According to the invention of claim 2, a facsimile line control circuit connected to a telephone line, a calling circuit provided in the facsimile line control circuit, and telephone communication connected to the facsimile line control circuit by a relay. By bypassing the base current between the circuit and the direct current resistance for separating the direct current for closing the line and the alternating current forming the signal provided in this telephone communication circuit by the first capacitor It is provided with a transistor circuit which can be set separately, and a promotion means for promoting the direct current of the telephone communication circuit to rapidly approach the rated value in the transition period.

According to the invention of claim 3, a facsimile line control circuit connected to a telephone line, a calling circuit provided in the facsimile line control circuit, and telephone communication connected to the facsimile line control circuit by a relay. A circuit, a telephone communication circuit provided in the telephone communication circuit and connected to a telephone line, and a direct current for separating a direct current for closing the line and an alternating current forming a signal provided in the telephone communication circuit A transistor circuit in which a resistance and an AC resistance can be separately set by bypassing a base current with a first capacitor, and a promotion for accelerating a direct current of the telephone communication circuit to rapidly approach a rated value in a transition period. And a resistance for direct current, which is provided in the facsimile line control circuit, for separating direct current for closing the line and alternating current forming a signal. A second transistor circuit in which an AC resistance can be set separately by bypassing a base current with a second capacitor, and a DC current of the facsimile line control circuit is set so as to rapidly approach a rated value in a transition period. It is provided with a second promoting means for promoting.

Further, in the invention of claim 4, as the facilitating means of claims 1 to 3, an alternating current interruption means for interrupting a direct current is provided in parallel with the first capacitor, and this is connected to the output side. , The voltage difference disappears.

Further, in the invention of claim 5, as a promoting means of claims 1 to 3, a switch for short-circuiting the high voltage side of the telephone communication circuit and the first capacitor is provided to charge the first capacitor. Can be charged.

Further, in the invention of claim 6, the facilitating means of claim 2 or 3 is a supply device for switching the power supply of the communication device to the telephone communication circuit while the calling circuit is making a call. is there.

[0012]

According to the invention of claim 1, the transistor circuit provided in the telephone communication circuit connected to the telephone line can separately set the DC resistance and the AC resistance by bypassing the base current with the capacitor. However, if the capacitor is not charged, the base current does not flow and the transistor does not operate, so it is in an open state in terms of direct current. As the capacitor is charged, the base current flows, the transistor operates, the current flows through the DC resistance, and the DC resistance of the circuit becomes the set value. Therefore, during a transitional period when a direct current voltage is applied to the telephone communication circuit by a relay or a switch, spike noise can be prevented by a facilitating means for rapidly bringing the direct current close to the rated value.

According to another aspect of the present invention, a facsimile line control circuit is connected to the telephone communication circuit, the telephone communication circuit is connected to the facsimile line control circuit by a relay, and a direct current resistance and an alternating current resistance are set in the telephone communication circuit. A transistor circuit and facilitating means are provided. When the calling operation of the calling circuit ends and the telephone communication circuit is switched to the relay by the relay, the capacitor of the transistor circuit is not charged in the telephone communication circuit, so it is in an open state in terms of direct current, so spike noise Will occur, but it will be prevented by the facilitating means for bringing the direct current close to the rated value.

According to another aspect of the invention, the telephone communication circuit is provided with a facsimile line control circuit, the telephone communication circuit is connected to the facsimile line control circuit by a relay, and the telephone communication circuit and the facsimile line control circuit have a DC resistor. Transistor circuits for setting AC resistances are respectively set, telephone communication circuits are provided with facilitating means for bringing DC current close to the rated value, and facsimile line control circuits are also provided with second promoting means for performing the same operation. Therefore, the generation of spike noise in each circuit is prevented.

According to a fourth aspect of the present invention, as the facilitating means used in the first to third aspects, an alternating current interruption means is provided in parallel with the first capacitor, and a direct current flows in the telephone communication circuit even in the transition period. Therefore, the generation of spike noise is prevented. When a direct current also flows into the first capacitor and charging proceeds, the transistor circuit operates, the direct current resistance is set, and the steady state is established. The constant voltage diode prevents an AC short circuit.

In a fifth aspect of the present invention, as a facilitating means of the first to third aspects, a switch that short-circuits the high voltage side of the telephone communication circuit and the first capacitor is provided, and this switch is closed during the transition period, and a direct current is supplied. Generation of spike noise is prevented by causing the first capacitor to flow. The switch is opened after the first capacitor is charged.

In a sixth aspect of the invention, as a facilitating means of the second or third aspect, a direct current power is supplied to the telephone communication circuit from the power supply of the communication device while the calling circuit is in the calling operation. As a result, the first capacitor is charged and the DC resistance is set to a set value when the telephone communication circuit is switched to, so that the DC current flows and the spike noise is prevented.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the first embodiment. The same symbols as those used in FIG. 9 have the same meaning. The same applies to the subsequent figures. This embodiment shows a communication-related circuit of a facsimile machine. A facsimile line control circuit 1 is connected to the telephone line terminals L1 and L2, and a telephone communication circuit 3 is connected to the facsimile line control circuit 1 via a CML relay 2. CML relay 2
When switching, 3 contacts are connected and can be switched without being opened. The facsimile line control circuit 1 is connected to a modem of a facsimile machine via a transformer 4, and a calling circuit 5 for calling a dial signal is provided.

The telephone communication circuit 3 includes a diode bridge 6 which prevents the positive and negative power supplies from being reversed when the telephone is connected to the telephone communication circuit 3, a hook switch 8 which operates when the handset 7 is put on and taken off, and a handset 7.
There is provided a speech circuit 9 which is connected to the device for voice communication, a third capacitor C3 provided in the present embodiment, and a constant voltage diode 11. The speech circuit 9 is provided with a DC / AC impedance adjusting circuit 10.
The basics of the DC / AC impedance adjustment circuit 10 are shown in FIG.
However, the circuit shown in FIG. 6 is also used. The same symbols as those in FIG. 10 represent the same meanings, R1 is a resistance for AC, R2 is a resistance for DC, and C1 is a first capacitor.

When the first capacitor C1 is charged and the voltage at the point B reaches a predetermined value, the diode D operates to apply a voltage dropped by 0.6 to 0.7 V to the bases of the transistors Tr1 and Tr2. Since Tr1 and Tr2 form a current mirror, when the collector current of Tr1 flows, the collector current of Tr2 also flows, and this current becomes the base current of the transistor Tr3 and the transistor Tr3.
Operates and a current flows through the DC resistance R2. An alternating current flows through the AC resistor R1 through the first capacitor C1. As described above, since the transistor Tr3 does not operate before the charging of the first capacitor C1 is started, it is in an open state in terms of direct current, but after charging, the direct current resistance becomes R2. The AC resistance is R1 regardless of charging.

FIG. 7 shows the state of current in the DC / AC impedance adjusting circuit 10 of FIG. (A) shows a state in which the charging current of the first capacitor C1 changes with time. (B) shows the change over time of the DC resistance, and the impedance decreases as the first capacitor C1 is charged, and becomes DC resistance R2 when the charging is completed. (C) is DC resistance R2
The time change of the direct current flowing through is shown. The direct current flowing through the speech circuit 9 becomes the current flowing through this R2.

Next, the third capacitor C3 and the constant voltage diode 11 connected in series thereto will be described. The constant voltage diode 11 is provided to maintain a constant voltage without short-circuiting with respect to alternating current. The third capacitor C3 is connected in parallel with the first capacitor C1, and when a voltage is applied to the telephone communication circuit 3, both charging currents flow.

FIG. 8 is a diagram showing the time variation of the current of the telephone communication circuit 3, where (A) is the charging current of the first capacitor C1,
7B shows a direct current flowing through the speech circuit 9 due to this charging current, which is the same as FIGS. 7A and 7C.
(C) shows the charging current of the third capacitor C3.
(D) shows a case where the charging current of the third capacitor C3 flows at the same time as the current of the speech circuit 9 shown in (B), and shows the state of the current in this embodiment. Current waveform shown in (B) and (C)
The current waveforms shown in (2) complement each other, and this combined waveform can be made a substantially constant current by adjusting the capacitances of the first capacitor C1 and the third capacitor C3. In this way, even if the voltage of the terminals L1 and L2 is applied to the telephone communication circuit 3, the direct current flows, so that the state is not opened in terms of direct current and the generation of spike noise can be prevented.

Next, a second embodiment will be described. FIG. 2 shows the circuit of the second embodiment. In this embodiment, the telephone communication circuit 3 is connected to the facsimile line control circuit 1 via the CML relay 2 as in FIG. 1, but the same parts are omitted. In this embodiment, the third capacitor C3 and the constant voltage diode 11 of the first embodiment are replaced with a short circuit switch 12 and a resistor 13. The resistor 13 is provided to limit the current at the time of short circuit and to secure the charging current of the first capacitor C1. An electronic switch such as a transistor is used as the short-circuit switch 12, and operates so that the first capacitor C1 is charged when the voltage is applied to the telephone communication circuit 3 and the direct current becomes a rated value. As a result, even if a voltage is applied to the telephone communication circuit 3, a DC current flows, so that spike noise or the like can be prevented from occurring.
The short-circuit switch 12 is controlled so that the direct current of the telephone communication circuit 3 has a substantially constant value.

As described above, the operations of the first and second embodiments are similar to short-circuiting the telephone line, and the combination of the capacitor and the constant voltage diode uses the short-circuit switch 12. It can be constructed at a lower price than the existing one. On the contrary, the configuration using the short-circuiting switch 12 can be finely controlled by software control even if the price is slightly higher.

Next, a third embodiment will be described. FIG. 3 shows a circuit of the third embodiment. This embodiment also has a facsimile line control circuit 1 and a CML relay 2 as in the second embodiment,
This is omitted and displayed. In this embodiment, a switch 14 is provided in series with the first capacitor C1 so that the telephone communication circuit 3 is charged rapidly when a voltage is applied. Although a photo coupler is used as the switch 14, an electronic switch such as a transistor may be used. In this embodiment, since the switch 14 provided in parallel with the AC resistance R1 directly charges the first capacitor C1, the charging current is larger than in the first and second embodiments in which the charging current flows through the AC resistance R1, and the charging is quick. And the charging current flows as direct current in the telephone communication circuit 3 to prevent a DC insulating state when a voltage is applied, and to prevent spike noise from occurring.

In the first to third embodiments, the telephone communication circuit 3 is CM.
The case where the facsimile line control circuit 1 is connected via the L relay 2 has been described, but the same applies when the telephone communication circuit 3 is directly connected to the telephone line.

Next, a fourth embodiment will be described. FIG. 4 is a block diagram showing the configuration of this embodiment. In this embodiment, a changeover switch 16 is provided in place of the third capacitor C3 and the constant voltage diode 11 of the first embodiment shown in FIG. 1 so that a current is supplied from the power supply 15 of the facsimile machine to the telephone communication circuit 3. It was done. When the CML relay 2 is closed and the telephone communication circuit 3 is not connected to the telephone line,
The changeover switch 16 connects to the power supply 15 to charge the first capacitor C1. As a result, even if a voltage is applied to the telephone communication circuit 3 by the CML relay 2, since the first capacitor C1 is in the charged state, the direct current is conducted, and spike noise can be prevented. This embodiment can be realized in a small space because only the changeover switch 16 is provided, and can be realized at low cost because only wiring is performed.

Next, a fifth embodiment will be described. This embodiment is different from the first embodiment in that the facsimile circuit control circuit 1 is also provided with a DC / AC impedance adjusting circuit 17, and a DC current at the time of voltage application is provided by a capacitor and a constant voltage diode as in the first embodiment. It is designed to maintain continuity. The circuit of the fifth embodiment is a circuit mainly in the case of adopting a transformer that cannot pass a direct current. This transformer is cheaper than the transformer used in the first embodiment and the like, and the number of components is taken into consideration. The price of the whole circuit can be reduced. In such a circuit, as compared with FIG. 1, the circuit to the transformer 4 includes a fifth capacitor C5 for blocking direct current, and the diode bridge 1 is connected in parallel with the transformer 4.
8 and a DC / AC impedance adjusting circuit 17 are provided.
The DC / AC impedance adjusting circuit 17 is the same circuit as in FIG. 10, the bypass capacitor is the second capacitor C2, the AC resistance is R3, the DC resistance is R4, and the transistor T
r4. Further, the fourth capacitor C4 and the constant voltage diode 19 are connected in series and are connected in parallel with the second capacitor C2. The operation is the same as that described in the first embodiment, and when a voltage is applied to the facsimile line control circuit 1, direct current is caused to flow by the charging current to the fourth capacitor to prevent generation of spike noise.

The fifth embodiment is a facsimile line control circuit 1
Although the case where the first embodiment is applied is shown in the above, the second embodiment, the third embodiment, and the fourth embodiment can be similarly applied. In this application, the facsimile line control circuit 1 and the telephone communication circuit 3 may be provided with the same facilitating means as shown in the fifth embodiment, but may be provided with different facilitating means.

[0032]

As is apparent from the above description, according to the present invention, the DC resistance and the AC resistance can be separately set by bypassing the base current with the capacitor when the voltage is applied to the transistor circuit. The provision of the means for promoting the current makes it possible to prevent the generation of spike noise.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment.

FIG. 2 is a block diagram showing a configuration of a second embodiment.

FIG. 3 is a block diagram showing the configuration of a third embodiment.

FIG. 4 is a block diagram showing the configuration of a fourth embodiment.

FIG. 5 is a block diagram showing a configuration of a fifth embodiment.

FIG. 6 is a diagram showing a DC / AC impedance adjustment circuit.

FIG. 7 is a diagram showing a state of current in the circuit of FIG.

FIG. 8 is a diagram showing a change in current in the first embodiment.

FIG. 9 is a diagram showing an example of a conventional circuit.

FIG. 10 is a diagram showing another example of the DC / AC impedance adjustment circuit.

FIG. 11 is a diagram showing generation of spike noise in the circuit shown in FIG. 9.

[Explanation of symbols]

 1 Facsimile line control circuit 2 CML relay 3 Telephone communication circuit 4 Transformer 5 Calling circuit 6,18 Diode bridge 7 Handset 8 Hook switch 9 Speech circuit 10, 17 DC / AC impedance adjusting circuit 11, 19 Constant voltage diode 12 Short circuit switch 13 Resistance 14 Switch 15 Power 16 Switch C1 1st capacitor C2 2nd capacitor C3 3rd capacitor C4 4th capacitor

Claims (6)

[Claims] 1. A telephone communication circuit connected to a telephone line, and a direct current resistor and an alternating current resistor provided in the telephone communication circuit for separating a direct current for closing a line and an alternating current forming a signal. Communication comprising a transistor circuit capable of being separately set by bypassing the base current with a first capacitor, and a facilitating means for facilitating the direct current of the telephone communication circuit to rapidly approach its rated value during the transition period. apparatus. 2. A facsimile line control circuit connected to a telephone line, a calling circuit provided in the facsimile line control circuit, a telephone communication circuit connected to the facsimile line control circuit by a relay, and the telephone communication circuit. The DC resistance and the AC resistance for separating the DC for closing the line and the AC forming the signal can be set separately by bypassing the base current with the first capacitor. A communication device comprising a transistor circuit and a facilitating means for facilitating a direct current of the telephone communication circuit to rapidly approach a rated value during a transition period. 3. A facsimile line control circuit connected to a telephone line, a calling circuit provided in the facsimile line control circuit, a telephone communication circuit connected to the facsimile line control circuit by a relay, and this telephone communication circuit. A telephone communication circuit connected to a telephone line, and a DC resistance and an AC resistance provided in the telephone communication circuit for separating a direct current for closing the line and an alternating current forming a signal. Transistor circuits that can be set separately by bypassing the current with a first capacitor; facilitating means for facilitating the direct current of the telephone communication circuit to rapidly approach its rated value during the transition period; and the facsimile line control. A DC resistance and an AC resistance, which are provided in the circuit and used to separate the direct current for closing the line and the alternating current that composes the signal, are connected to the base current. A second transistor circuit that can be set separately by bypassing with a second capacitor, and a second facilitating means that promotes the direct current of the facsimile line control circuit to rapidly approach the rated value during the transition period. A communication device comprising: 4. The alternating current interrupting means for interrupting alternating current and passing direct current is provided in parallel with the first capacitor, and the alternating current interrupting means is a promoting means. 4. The communication device according to any one of 3 to 3. 5. The communication according to claim 1, further comprising a switch that short-circuits the high voltage side of the telephone communication circuit and the first capacitor, and the switch serves as a facilitating means. apparatus. 6. The communication device according to claim 2, wherein the facilitating means is a supply device that switches the power supply of the communication device and supplies the power to the telephone communication circuit while the calling circuit is making a call. .