JPH06291876A - Direct current loop closing circuit for telephone line - Google Patents

Abstract

PURPOSE:To easily switch to data communication after response over a telephone set, to prevent malfunction, to obtain direct current loop currents which fulfill the function even of an electronic telephone set, and to have the opportunity of the response over the telephone set even at the time of the automatic response by a data terminal. CONSTITUTION:In a telephone device in which the data terminal is connected with the telephone line in parallel to the telephone set, the direct current loop circuit of the data terminal is equipped with photocouplers PC1 and PC2, and when the telephone set is off-hooked, the direct current loop circuit of the data terminal is formed of a high resistance by controlling the photocouplers PC1 and PC2, and most of the direct current loop currents are allowed to run through the telephone set. Then, when the telephone set is on-hooked, the direct current loop circuit of the data terminal is formed of the low resistance by controlling the photocoupler PC2, and the current value is returned to a normal value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone device which shares a telephone line with a telephone and a data terminal.

[0002]

2. Description of the Related Art In a conventional telephone device in which a telephone line is shared by a telephone and a data terminal, a signal sent from a data terminal on the originating side when the originating side is a data terminal when an answer is received on the telephone. By hearing the sound and knowing that the data terminals are communicating with each other, and pressing the start button of the own data terminal, the telephone line is switched to the data terminal side and data communication becomes possible.

When the telephone side goes on hook, the telephone returns to the normal state.

When the data communication is completed, the data terminal automatically opens the DC loop, disconnects the telephone line, and returns to the normal state.

When an incoming call arrives and the data terminal automatically answers before answering with the telephone, when the calling side is the data terminal, the signal tone sent from the calling side is received and the data communication is directly started.

When the originating side is a telephone, no signal tone is sent from the originating side, so the data terminal waits for the arrival of the signal tone for a certain period of time, opens the DC loop, and disconnects the telephone line. That is, in this case, the incoming call becomes an invalid call.

[0007]

According to the above-mentioned prior art, when a caller answers a call when a call arrives, if the caller is a data terminal, the responder hears a signal tone from the caller and knows that the call is data communication. Press the start button of your data terminal to switch the telephone line to the data terminal side, and then on-hook to return the telephone to the normal state.

At this time, if the operation procedure is mistaken and the start button of the data terminal is pushed after the on-hook on the telephone, the incoming call is disconnected. Further, it is inconvenient to press the start button when the telephone and the data terminal are separated.

An object of the present invention is to eliminate the above inconvenience or inconvenience.

According to the prior art, when the data terminal first answers automatically when receiving a call, and if the calling side is a telephone, the data terminal waits for a certain period of time after the automatic answer and the signal tone does not come and disconnects the telephone line. Therefore, the call becomes invalid. Even if the telephone is switched on-hook after waiting for a signal for a certain period of time after the data terminal automatically responds, the telephone line is switched to the data terminal side, so the telephone cannot respond.

According to the present invention, it is possible to respond to a telephone while waiting for a certain period of time after the data terminal automatically responds,
It is an object to prevent the generation of invalid calls as much as possible.

Further, in the past, as a method of switching to the data terminal side when an incoming call is answered by the telephone, it is not necessary when the telephone and the data terminal are connected in parallel to the telephone line and then a call or data communication is determined. The way to cut the free side is taken. According to this method, there is a state in which the telephone and the data terminal are connected in parallel to the telephone line. In this state, the line current is shunted between the telephone and the data terminal, so that the current flowing in the telephone is independently connected to the telephone line. It decreases more. If the telephone is an electronic telephone and all of its functions are based on the power supplied by the line current,
Since the electric power supplied from the line current decreases, there is a possibility of malfunctioning, and the prevention of this phenomenon becomes an issue.

[0013]

In order to solve the above problems, the present invention is a telephone device in which a telephone and a data terminal are connected in parallel to a telephone line, and is inserted in a communication path between the telephone and the telephone line. , A hook state detecting means (specifically, an off-hook detecting circuit 5) for detecting a hook state (on-hook or off-hook) of a telephone, and an incoming-call detecting means (specifically, an incoming-call detecting circuit 2) for detecting an incoming call from a telephone line. ) And a timer that starts when the incoming call detection means detects an incoming call and measures a set time defined as a standby time until an automatic response is made at the data terminal (specifically, a timer set by a program in the CPU 4) By the timer measuring the set time, or by the hook state detecting means detecting the off-hook of the telephone before the set time. Loop forming means for forming a direct current loop of the telephone line for the data terminal (specifically, photocoupler PC1 and its related circuit and photocoupler PC1 control program of CPU4), and the direct current loop is formed by the loop forming means. When the hook detecting means detects the on-hook of the telephone, the current flowing through the DC loop is increased, and when the hook state detecting means detects the off-hook of the telephone, the current flowing through the DC loop is increased. A DC loop closure circuit is constituted by the current control means (specifically, the photocoupler PC2, the resistors R1 and R2, and the photocoupler PC2 control program of the CPU 4) for controlling so as to decrease the DC loop closure circuit. , Power supply for telephone status monitoring (specifically monitoring power supply 6) and timer When the call path of the telephone including the hook state detection circuit is switched from the telephone line to the power source for state monitoring by measuring the time, then the hook state detection means detects off-hook of the telephone, and when the data terminal is not in the data communication state, Switching means for switching the call path of the above-mentioned telephone to the telephone line side again (specifically, the relay TC and its related circuit and the relay TC of the CPU 4).
A control program) is further provided.

[0014]

According to the present invention, when a call is answered by the telephone when an incoming call is received, the off-hook of the telephone is detected and a DC loop is automatically created on the data terminal side, so that the telephone and the data terminal are connected in parallel to the telephone line to make a call. When the side is a data terminal, the data terminal can directly enter data communication by listening to the signal tone sent from the originating data terminal and simply on-hooking at the telephone side.

If the data terminal first responds automatically when receiving a call, the data terminal waits for a confirmation signal of data communication for a certain period of time after the automatic response, and if the calling side is a telephone, the signal is sent. Since it is not sent, the telephone line is opened after a lapse of a certain time, but if the telephone is off-hook by the off-hook detection circuit of the above-mentioned data terminal during the signal arrival waiting time of the above-mentioned data terminal, it is switched by the output of the off-hook detection circuit. You can enter the call by controlling the relay and connecting the telephone to the telephone line side. The data terminal is opened after the elapse of the certain time.

When the telephone responds to an incoming call, the line current is shunted to both the telephone and the data terminal by connecting the data terminal to the telephone line in parallel with the telephone as described above, but the telephone is off-hook. In this case, the function of the telephone is controlled by reducing the current flowing in the DC loop circuit on the data terminal side by the output of the off-hook detection circuit to a small current that does not hinder data reception, and controlling so that most of the current flows through the telephone. Can be satisfied.

[0017]

FIG. 1 is a circuit diagram showing an embodiment of the present invention,
L1 and L2 are connection terminals of the telephone line L, T1 and T2 are connection terminals of the telephone TEL, 1 is a rectifier circuit, 2 is an incoming call detection circuit, 3 is a modem circuit, 4 is a CPU, 5 is an off-hook detection circuit, and 6 is a telephone. Monitoring power supply for TEL status monitoring,
PC1 is a photocoupler for closing the DC loop on the data terminal TM side, PC2 is a photocoupler for controlling the DC loop current on the data terminal TM side, TC is a relay for switching the telephone TEL between the telephone line L and the monitoring power supply 6, and tc is a relay TC. Contact, T
Is a transformer that connects the telephone line L and the modem circuit.

The transistor Q1, the resistors R1 to R3 and the light receiving portion of the photocoupler PC2 form a DC loop circuit on the data terminal TM side with respect to the telephone line L, and the transistor Q2 and the resistors R6 to R8 emit light from the photocoupler PC1. Drive circuit of the light emitting portion of the photocoupler PC2 is configured by the transistor Q3 and the resistors R9 to R11, and the transistor Q4 and the resistors R12 and R13 are configured.
A drive circuit for the relay TC is configured by the diode D and the diode D.

(A) and (b) are jump symbols, and the same symbols are connected.

As a general operation method of this telephone device, the following method is adopted.

(1) When there is a person on the side of the telephone TEL in the daytime, or when there are many incoming calls (voice calls) to the telephone TEL, from when the incoming signal is received until the data terminal TM automatically answers. By setting a relatively long time and making the timing at which the telephone TEL can respond longer, the telephone TE
The operation is mainly based on the response by L.

(2) When there is no person on the side of the telephone TEL at night, or when data communication is the main and there are few voice calls, the time from receiving the incoming signal to automatically answering at the data terminal TM. By making it relatively short, the main operation is automatic response by the data terminal TM.

When there is an incoming call on the telephone line L, terminals L1 and L2
When an incoming signal arrives at, the incoming signal is applied to the terminals T1 and T2 via the contact point tc and the off-hook detection circuit 5, and the telephone TEL rings. The incoming signal is also input to the incoming detection circuit 2 connected in parallel to the terminals L1 and L2, the incoming detection circuit 2 detects the incoming call and adds the output to the CPU 4, and the CPU 4 automatically responds at the data terminal TM. To start the timer in CPU4.

If the telephone unit TEL responds prior to the automatic response of the data terminal TM, the incoming signal is stopped, and the above-mentioned CPU
The timer in 4 stops.

The off-hook detection circuit 5 detects the off-hook in response to the response from the telephone TEL and applies its output to the CPU 4. When the CPU 4 knows the off-hook of the telephone TEL and drives the transistor Q2 to turn on the light emitting portion of the photocoupler PC1, the light receiving portion of the photocoupler PC1 inserted in the communication line is turned on, and the transistor Q1 on the data terminal TM side is turned on. The light receiving part of the photocoupler PC2,
A DC loop circuit is formed by a DC loop circuit composed of resistors R1 to R3. This enables the modem circuit 3 to receive the signal sound from the telephone line L.

On the other hand, before the response from the telephone TEL, the telephone TE
Since the off-hook signal is not input from the off-hook detection circuit 5 due to the on-hook state of L, the transistor Q3 is turned on under the control of the CPU 4, and therefore the light emitting portion of the photocoupler PC2 is turned on and its light receiving portion is also turned on. ing.

The light receiving portion of the photocoupler PC2 is connected in parallel with the resistor R2 of the DC loop circuit of the data terminal TM, and the resistor R2 increases the loop resistance of the DC loop circuit and decreases the DC loop circuit current. However, before the response of the telephone TEL, the resistor R2 is short-circuited because the light receiving portion of the photocoupler PC2 is turned on as described above, and the loop resistance of the DC loop circuit is reduced to reduce the DC loop circuit current. It is controlled to increase.

In this state, as described above, the telephone TEL responds and the off-hook signal from the off-hook detection circuit 5 becomes CP.
When added to U4, the CPU 4 turns off the transistor Q3 and turns off the light emitting portion of the photocoupler PC2, which causes the photocoupler P inserted in the DC loop circuit.
Since the light receiving part of C2 is turned off, the photo coupler PC
The resistor R2, which is connected in parallel with the light receiving portion of 2, is released from the short circuit and is inserted into the emitter of the transistor Q1.
Also, the DC loop circuit current is reduced within a range in which the light receiving portion of the photocoupler PC1 can be kept on. Therefore, most of the line current from the telephone line L flows into the telephone TEL, which satisfies the function of the telephone TEL.

That is, when the telephone TEL is on-hook or when the data terminal TM is in the data communication mode (when the data terminal TM is in the data communication mode, regardless of the on-hook / off-hook of the telephone TEL), the photocoupler PC2 is turned on. Causes the DC loop circuit current on the data terminal TM side to increase, and when the telephone TEL is off-hook before the data terminal TM is set to the data receiving mode, the photo coupler PC2 is turned off to turn off the data terminal TM side. DC loop circuit current is reduced and the telephone TEL
The side DC loop current is controlled so as to increase.

When the call is sent from the telephone TEL, if the calling side is the telephone, a normal call is made as it is. When the originating side is a data terminal, a signal tone for identifying the data communication from the originating side data terminal arrives. At this time, in the data terminal TM, even when the telephone TEL is in the off-hook state, the light receiving portion of the photocoupler PC1 is turned on and the DC loop circuit is held as described above, so the signal tone is received by the modem circuit 3. Thereafter, signals are transmitted and received via the modem circuit 3 to enter the data communication mode.

When the telephone TEL hears the signal tone from the transmitting side data terminal and knows that it is an incoming call for data communication and goes on-hook, the own data terminal TM receives the signal tone from the transmitting side data terminal. After that, a signal is exchanged between both data terminals, and the subsequent operation is slightly different depending on which timing of entering the data communication mode is earlier.

When the data terminal TM enters the data communication mode before the on-hook of the telephone TEL, the data communication mode signal is input from the modem circuit 3 to the CPU 4. The CPU 4 drives the transistor Q4 to operate the relay TC. By the operation of the relay TC, the telephone TEL is switched from the telephone line L to the monitoring power source 6 and is disconnected from the telephone line L so as not to affect the data communication. At this time, since the telephone TEL is still off-hook, the off-hook detection circuit 5 is supplied with power from the monitoring power supply 6 and continues to output. In the CPU 4, the output of the off-hook detection circuit 5 continues to be output because the CPU 4 has entered the data communication mode, but regardless of this, the transistor Q3 is driven at the same time as the operation of the relay TC to turn on the light emitting portion of the photocoupler PC2. Then, the light receiving part is turned on and the resistor R2 is turned on.
Is short-circuited, and the current of the DC loop circuit of the data terminal TM is increased to a normal value. Further, the transistor Q2 is continuously driven, and the ON state of the photocoupler PC1 continues to hold the DC loop circuit of the data terminal TM.

When the telephone TEL goes on-hook, the output of the off-hook detection circuit 5 disappears, but as described above, the transistor Q2 and the photocoupler PC1 maintain the on-state, and the data communication is performed in this state.

When the telephone TEL goes on-hook before the data terminal TM enters the data communication mode, the data terminal TM is already connected to the telephone line L as described above, and therefore the data terminal TM is connected to the telephone line L as in the conventional system. There is no need to press the start button, and you can simply go on hook. Although the output of the off-hook detection circuit 5 disappears due to the on-hook of the telephone TEL, the CPU 4 continuously drives the transistor Q2 by the input from the modem circuit 3, the photocoupler PC1 continues to be in the on-state, and the DC loop of the data terminal TM. Hold the circuit. Further, since the output of the off-hook detection circuit 5 disappears, the CPU 4 drives the transistor Q3 to turn on the photocoupler PC2 as described above,
The resistor R2 is short-circuited to increase the current in the DC loop circuit of the data terminal TM to a normal value.

When the data terminal TM subsequently enters the data communication mode, the modem circuit 3 sends a signal to that effect to the CPU.
4 and the CPU 4 receives the signal and the transistor Q4
Is driven to operate the relay TC to switch the telephone TEL from the telephone line L to the monitoring power supply 6 and disconnect it from the telephone line L so as not to affect data communication. Data communication is performed in this state.

When the data communication is completed, the signal of the data communication mode from the modem circuit 3 to the CPU 4 disappears, the transistor Q2 is turned off and the photocoupler PC1 is turned off, the DC loop is opened and the telephone line L is opened and empty. Return to the state of. Also, from CPU4 to transistor Q4
Is turned off, the relay TC is restored, the telephone TEL is connected to the telephone line L, and the normal state is restored.

When there is an incoming call on the telephone line L, the CPU 4 starts the timer for the response on the data terminal TM side as described above. If there is no response on the telephone TEL, the transistor Q2 is driven after a certain time. Then, the light emitting portion of the photocoupler PC1 is turned on, and the light receiving portion of the photocoupler PC1 is turned on to turn on the transistor Q1,
A DC loop circuit is formed via the light receiving portion of the photocoupler PC2 (which is turned on by the onhook of the telephone TEL) and the resistors R1 and R3, and the data terminal TM automatically responds.

After the automatic response, the CPU 4 newly starts a signal sound monitoring timer to monitor the arrival of signal sound for data communication. Further, the CPU 4 drives the transistor Q4 at the time of automatic response to operate the relay TC. Relay T
The operation of C switches the telephone TEL from the telephone line L to the monitoring power supply 6.

When the originating side is a data terminal and a signal sound from the data terminal arrives before the time of the signal sound monitoring timer expires, the data terminal TM receives the signal sound, stops the signal sound monitoring timer, and arrives and terminates. Signals are exchanged between both data terminals and the data communication mode is set to start data communication.

If the telephone TEL goes off-hook while the data communication mode is set, the off-hook detection circuit 5 detects the off-hook and applies its output to the CPU 4.
Since U4 is in the data communication mode, the transistors Q3 and Q4 continue to be driven, so that the photocoupler PC2 keeps ON to keep the current of the DC loop circuit of the data terminal TM at a normal value, and the relay TC has The telephone TEL continues to operate and the telephone TEL is disconnected from the telephone line L, and the telephone TEL is used for data communication.
Is controlled so that it is not affected by noise. If the telephone TEL goes off-hook in this state, the output of the off-hook detection circuit 5 is applied to the CPU 4, but the CPU 4 ignores this output, so that the data terminal TM is not affected.

When the data communication is completed, the data communication mode is released, and the CPU 4 turns off the transistors Q2 and Q4 and turns off the photocoupler PC1, so that the DC loop circuit of the data terminal TM is opened and the telephone line L is disconnected. To do. The relay TC is also restored and the telephone TEL is connected to the telephone line again to prepare for the next call.

When the data terminal TM detects an incoming call and responds automatically after a certain timing, the CPU 4 operates the relay TC while keeping the timing for waiting for the signal sound for the data communication to monitor the telephone TEL. Switch to 6. When the calling side is a telephone, the signal sound does not come, so the signal monitoring timer in the CPU 4 times out, and the CPU 4 turns off the transistor Q2,
The light emitting portion of the photocoupler PC1 is turned off. Therefore, the light receiving portion of the photocoupler PC1 is turned off and the data terminal TM
Since the DC loop circuit on the side is opened, the call is normally disconnected, and the transistor Q4 is controlled to be turned off. The relay TC is restored and the telephone TEL is connected to the telephone line L to prepare for the next call.

However, if the signal monitoring timer goes off-hook by the telephone TEL before the time-out, the telephone TEL receives current from the monitoring power source 6 through the contact tc and the off-hook detection circuit 5 receives the current because the relay TC is operating. Off-hook of the telephone TEL is detected,
The detection output is applied to the CPU 4, and the CPU 4 detects the off-hook of the telephone TEL, and at this time, the data terminal T
Since M is not in the data communication mode yet, the transistor Q4 is turned off and the relay TC is restored. When the relay TC is restored, the telephone TEL is connected to the telephone line L via the contact point tc and can start a call. Further, at this time, the CPU 4 turns off the transistor Q3 and turns off the photocoupler PC2 to decrease the current in the DC loop circuit on the data terminal TM side as described above, and to reduce the DC loop current on the telephone TEL side to a current satisfying the function. increase.

In the data terminal, when the signal monitoring timer does not make a signal sound and times out, the CPU 4 turns off the transistor Q2 and turns off the photocoupler PC1 so that the DC loop circuit of the data terminal TM is opened and restored. Therefore, thereafter, a call is made in a state where only the telephone TEL is connected to the telephone line L.

When the call ends and the telephone TEL goes on-hook, everything returns normally.

[0046]

When an incoming call is answered by the telephone, the DC loop on the data terminal side is closed at the same time, and the data communication circuit is connected in parallel with the telephone. The data terminal side can enter the data communication simply by listening to the signal sound of and going on hook. Therefore, the telephone does not need to operate the start button of the data terminal, it is possible to prevent disconnection of the line by mistake in the operating procedure, and it is also possible to place the telephone and the data terminal at a place apart from each other.

When the data terminal automatically answers the incoming call, and when the calling side is the telephone, the call cannot be answered later by the telephone, resulting in an invalid call.
If the telephone responds within the PU signal monitoring timer, the telephone line is switched to the telephone and the telephone call can be started.

When the telephone is answered at the time of incoming call, the DC loop on the data terminal side is simultaneously closed and the data communication circuit is connected in parallel with the telephone, so that the DC loop current of the telephone line is shunted to both the telephone and the data terminal. However, according to the present invention, the photocoupler PC2 of the DC loop circuit of the data terminal is controlled by on-hook and off-hook of the telephone, and when the telephone and the data terminal are connected in parallel to the telephone line, the DC loop circuit of the data terminal side is connected. Since the current is reduced and the DC loop current on the telephone side is increased, even when the telephone is an electronic telephone, a current satisfying its function can be passed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

[Explanation of symbols]

L1, L2 ... Connection terminal of telephone line L T1, T2 ... Connection terminal of telephone TEL 1 ... Rectifier circuit 2 ... Incoming detection circuit 3 ... Modem circuit 4 ... CPU 5 ... Off-hook detection circuit 6 ... For state monitoring of telephone TEL Monitoring power supply PC1 ... Photo coupler for closing DC loop of data terminal TM side PC2 ... Photo coupler for controlling DC loop current of data terminal TM side TC ... Relay for switching telephone TEL between telephone line L and monitoring power supply 6 ... Contact of relay TC T: A transformer that connects the telephone line L and the modem circuit

Claims (2)

[Claims] 1. In a telephone device in which a telephone and a data terminal are connected in parallel to a telephone line, a hook state detecting means which is inserted into a call path of the telephone and the hook state detecting means detects the hook state of the telephone, and the telephone line. An incoming call detecting means for detecting an incoming call from the device, and a timer which starts when the incoming call detecting means detects an incoming call and measures a set time defined as a waiting time until the data terminal automatically answers,
Loop forming means for forming a direct current loop of the telephone line to the data terminal by the timer measuring the set time or by the hook state detecting means detecting the off-hook of the telephone before the set time is measured. When the DC loop is formed by the loop forming means, the hook state detecting means increases the current flowing in the DC loop when the hook state detecting means detects the on-hook of the telephone, and the hook state detecting means causes the off-hook of the telephone. The DC loop closed circuit of the telephone line, which is a current control means for controlling so as to reduce the current flowing through the DC loop. 2. The direct current loop closed circuit of the telephone line according to claim 1, wherein a power supply for monitoring the state of the telephone is provided, and a call path of the telephone including a hook state detecting means is set by the timer counting the set time. When the hook line detecting means detects the off-hook of the telephone and the data terminal is not in the data communication state after the telephone line is switched to the power supply for state monitoring, the communication path is switched to the telephone line side again. Telephone loop DC loop closure circuit.