JPH0744117Y2 - Telephone line switching circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a telephone suitable for use when a telephone or the like and another communication terminal device or the like are communicated using a single telephone line. The present invention relates to a line switching circuit, and particularly to a telephone line switching circuit having a prior use priority function and a modem priority mechanism.

[Prior Art] Recently, the use of personal computer communication is expanding, but when personal computer communication is performed, data communication is performed by connecting a modem to a telephone line and connecting a terminal line and a host station through the telephone line. ing.

On the other hand, in a general household, there is usually only one telephone line, and in such a case, a telephone is already connected to this telephone line.

Therefore, when personal computer communication is carried out in a general household having only one telephone line, the telephone and the modem required for personal computer communication switch and use this one telephone line.

[Problems to be solved by the invention] However, when switching between a telephone and a modem on one telephone line, for example, when using the telephone, a modem is used on the telephone line to use the modem. When connected, there is a risk that the call will be automatically cut off and the call may be disturbed.

Also, if a modem is connected to a telephone line and the telephone line is switched to the telephone side without knowing during data communication and the telephone line is used, an important data error may occur and the data may be erroneously lost. There was

This invention was made in view of the conventional drawbacks.
When there is only one telephone line, when sharing the telephone and the modem, when one of them is used, the other cannot be connected to this telephone line to prevent mutual interference, and (EN) Provided is a telephone line switching circuit which enables a telephone line user to easily select a priority according to the application by switching to a modem priority connection mechanism.

[Technical Means for Solving Problems] In the present invention, in a telephone line switching circuit that uses a single telephone line and switches between the telephone and the modem, the telephone is connected to the telephone line. First switching means including a switch and a relay for controlling the switch, second switching means including a switch for connecting the modem to a telephone line and a relay for controlling the switch, and off-hook of the telephone are detected. Off-hook detecting means, and the first signal based on the signal from the off-hook detecting means and the signal from the modem controller.
And a control means for controlling each switching via the relay of the second switching means, and a priority switch for manual operation for enabling or disabling the off-hook detection means. The first-use priority function, in which the off-hook means is enabled, prohibits the modem from being connected to the telephone line based on the off-hook signal from the off-hook detection means when using the telephone, and when the modem is used, it is obtained from the modem side. The control means operates so as to prohibit the telephone from being connected to the telephone line on the basis of the control signal, and the telephone is used in the modem priority function in which the off-hook detection means is disabled by the priority switch. Even if the above-mentioned control means operates so that the modem is preferentially connected to the telephone line It is characterized by.

Specifically, a first switching means connected on the line between one of the pair of terminals for the telephone line and the telephone body, a second switching means connected between the pair of terminals, and A control means for controlling the pair of switching means and a priority switch provided in the control means are provided, and when the priority switch is operated, the modem is preferentially connected to the telephone line. It is characterized in that the first and second switching means are controlled.

[Operation] In this invention, the first switching means 4 is connected in series on the line L1 between one of the pair of terminals 2 for the telephone line and one terminal 3A of the telephone body 3, and Terminals L1, L2
The second switching means 5 is connected in parallel between them.

These pair of switching means 4 and 5 make the modem 6
Alternatively, the telephone 3 is connected to the telephone line 1.

These pair of switching means 4 and 5 are priority switches 15
It is controlled by the control means 11 having the following. When the priority switch 15 is opened, the modem has priority and the telephone line 1
The first and second switching means 4 and 5 are controlled by the control means 11 to preferentially connect the modem 6.

On the other hand, when the priority switch 15 is closed, the first use is prioritized, and the first used one of the modem 6 and the telephone 3 is given priority, and the other cannot use the telephone line 1. The control means 11 controls the first and second switching means 4 and 5 so as to achieve such a control mode.

Therefore, interruption of the modem 6 is prohibited while the telephone 3 is used, and conversely, the telephone 3 cannot be used while the modem 6 is used.

As a result, it is possible to prevent mutual interference such as disconnecting a call or losing important data.

Further, the prior use priority function and the modem priority function can be easily selected by switching the priority switch according to the use of the user.

[Embodiment] The present invention will be described in detail with reference to the drawings.

The figure is a diagram showing an example of the configuration of the present invention.

In the figure, reference numeral 1 is a telephone line, and its end 2 is provided with lines L1 and L2. A telephone 3 is connected to the terminal 2 of the telephone line 1 in addition to the modem 6. First and second switching means 4, for switching between the telephone 3 and the modem 6,
It has 5.

The first switching means 4 is provided in series on the line L1 between one terminal 3A of the telephone 3 and the terminal 2 of the telephone line. First
The switching means 4 comprises a relay 41 and a normally closed switch 42.

The second switching means 5 is connected in parallel between the lines L1 and L2. The second switching means 5 comprises a relay 51 and a normally open switch 52.

Signal exchange between a personal computer (not shown) and the telephone line 1 is performed via the modem 6.

Reference numeral 7 denotes a modem controller (hereinafter referred to as CPU).

That is, when sending a signal from a personal computer, first, CPU7
The signal is modulated in the modulator / demodulator circuit 8 via the line and sent to the telephone line 1 via the operational amplifier 9A in the hybrid circuit 9 and the line transformer 10.

Further, the signal from the telephone line 1 passes through the operational amplifier 9B in the line transformer 10 hybrid circuit 9 and the modulator / demodulator circuit 8
To the personal computer (not shown) via the CPU 7 to demodulate the transmission signal.

A control means 11 for controlling the first and second switching means 4 and 5 is provided.

The control means 11 is composed of a gate circuit 12, a detection circuit 13, relay drivers 14A and 14B, and a priority switch 15.

The detector 13 is composed of a phototransistor 13A and a photocoupler 13B.

The phototransistor 13A is turned on when its hook is turned off to use the telephone 3 and the priority switch 15 is turned on. That is, the terminals 3A, 3 of the telephone 3
By connecting B to the telephone lines L1 and L2, the loop current flows to the photocoupler 13B and the phototransistor 13A
To turn on. As a result, a low level signal is supplied to the gate circuit 12.

The gate circuit 12 is composed of two AND circuits, and supplies the same control command signal from the CPU 7 to each, and also supplies the signal from the phototransistor 13A of the detection circuit 13. Further, the output signal of the gate circuit 12 is supplied to the relays 41, 51 of the first and second switching means 4, 5 via the relay drivers 14A, 14B.

The priority switch 15 is a switch for switching between the first use priority function and the modem priority function.

The prior use priority function is a function of prohibiting the use of the telephone 3 while the personal computer is using the telephone line 1 and prohibiting the interruption of the personal computer while the telephone 3 is using the telephone line 1. In other words, this is a function that gives priority to the person who is using the telephone line 1 first.

On the other hand, the modem priority function is a function of prohibiting the use of the telephone 3 while the personal computer is using the telephone line 1 and preventing a partial lack of transmission data. In other words, the modem 6 is given priority. It is a function to connect to the telephone line 1.

Now, the switching operation of the telephone line switching circuit configured as described above will be described separately for the above-mentioned prior use priority function and modem priority function.

First, for convenience of explanation, the function of prior use will be explained first.

In this case, the priority switch 15 is turned on (the illustrated switching state). It is assumed that a low level signal is sent from the CPU 7 to the gate circuit 12 as a control command signal when the personal computer is not used, and a high level command signal is sent to the gate circuit 12 when the personal computer is in use. The first and second switching means 4 and 5 are assumed to be switched to the illustrated state. That is, the line L1 is connected to the terminal 3A by the normally closed switch 42 of the first switching means 4.

In this initial state, the telephone 3 is on-hook,
Therefore, no current flows through the photocoupler 13B, and the phototransistor 13A is off.

Therefore, although the high level signal is supplied to the gate circuit 12, since the low level signal is transmitted from the CPU 7 as described above, the low level signal is transmitted from the gate circuit 12.

This gate signal is passed through the relay drivers 14A and 14B to the first
Is supplied as a high level signal to the relay 41 forming the switching means 4 and the relay 51 forming the second switching means 5.

However, since the other ends of the relays 41 and 51 are respectively connected to a predetermined DC power source, the relays 41 and 51 are not energized by this gate signal and, as a result, the line
L1 remains connected to the terminal 3A by the normally closed switch 42 of the first switching means 4. In this initial state, the telephone 3 is now hooked off to use it.
Then, a predetermined loop current flows through the lines L1 and L2 and the terminals 3A and 3B.

Therefore, a current flows through the photocoupler 13B, so that the phototransistor 13A is turned on and the low-level signal is supplied to the gate circuit 12.

On the other hand, since the low level signal is sent from the CPU 7, the low level signal is sent from the gate circuit 12.

This gate signal is passed through the relay drivers 14A and 14B to the first
Is supplied as a high level signal to the relay 41 forming the switching means 4 and the relay 51 forming the second switching means 5.

However, as described above, since the other ends of the relays 41 and 51 are connected to predetermined DC power sources, respectively,
41 and 51 are not energized by this gate signal, as a result of which the line L1 remains connected to the terminal 3A via the normally closed switch 42 of the first switching means 4 and this state is maintained. You can make calls.

As a result, only the telephone 3 is connected to the telephone line 1. When a personal computer is used in such a state, a high-level command signal is sent from the CPU 7 to the gate circuit 12
However, since the priority signal holds the low level, the polarity of the gate signal is not inverted.

That is, even if the personal computer is used while the telephone 3 is in use, the modem 6 cannot be connected to the lines L1 and L2, and the interruption is prohibited.

On the other hand, in the initial state, when the personal computer is used, the CPU 7 sends a high level command signal to the gate circuit 12. On the other hand, since the telephone 3 is in the on-hook state, no loop current flows in the photocoupler 13B. Therefore, since the phototransistor 13A is in the off state, one input of the gate circuit 12 is a high level signal. Therefore, the gate circuit 12 outputs a high level gate signal. This gate signal is relay driver 14A, 14B
Is supplied as a low-level signal to the relays 41 and 51 which constitute the first and second switching means 4 and 5, via the.

Therefore, the relay 41 and the relay 51 are energized by this gate signal, the lines L1 and L2 are inverted to the closed state, and the line L1 is inverted to the terminal 3A not connected.

Therefore, only the modem 6 is connected to the telephone line 1.

In such a state, even if the hook is turned off to use the telephone, the first switching means 4 is reversely controlled to be in the open state, and therefore the lines L1 and L2 are connected to the terminal 3
No current flows because it is not connected to A and 3B. Therefore, the phototransistor 13A maintains the off state. Therefore, the high level signal is supplied to the gate circuit 12 as in the previous state,
The polarity of the gate signal is not inverted.

That is, the telephone 3 cannot be used while the personal computer is in use.

Therefore, in the prior use priority function, interruption of the modem 6 is prohibited while the telephone 3 is used, and conversely, the telephone 3 cannot be used while the modem 6 is used. As a result, it is possible to prevent mutual interference such as disconnecting a call or losing important data.

Next, the modem priority function will be described.

In this case, the priority switch 15 is controlled to be in the OFF state, and the rest are in the same initial state as in the case of the prior use priority function.

In the initial state, the CPU 7 supplies a high level command signal to the gate circuit 12 by using the personal computer. At this time, since the priority switch 15 is in the off state, the phototransistor 13A is always in the off state, thereby supplying the high-level signal to the gate circuit 12.

Therefore, the gate circuit 12 outputs a high level gate signal. The gate signal is transmitted via relay drivers 14A and 14B to the relays 41 and 41 which constitute the first and second switching means 4 and 5, respectively.
It is supplied to 51 as a low level signal.

The relay 41 and the relay 51 are energized by this gate signal, so that the lines L1 and L2 are closed and the line L1 and the terminal 3 are closed.
A is not connected.

Therefore, only the modem 6 is connected to the telephone line 1.

Even if the hook is turned off in order to use the telephone in such a state, the lines L1 and L2 are not connected to the terminals 3A and 3B and the current does not flow because the first switching means 4 is in the open state. . Furthermore, since the priority switch 15 is off, the polarity of the signal to the gate circuit 12 is not inverted.

That is, the telephone 3 cannot be used while using the personal computer.

On the other hand, in the initial state, when the telephone 3 is put into the hook-off state for use, a predetermined loop current flows through the lines L1 and L2 and the terminals 3A and 3B.

Therefore, a current flows through the photocoupler 13B, but since the priority switch 15 is switched to the off state, the phototransistor 13A maintains the off state and supplies a high-level signal to the gate circuit 12.

However, since the low-level signal is sent from the CPU 7, the low-level signal is sent from the gate circuit 12.

This gate signal is passed through the relay drivers 14A and 14B to the first
Is supplied as a high level signal to the relay 41 forming the switching means 4 and the relay 51 forming the second switching means 5.

However, since the other ends of the relays 41 and 51 are respectively connected to predetermined DC power sources, the relays 41 and 51 are
Is not activated by this gate signal, so that the line L1 remains connected to the terminal 3A by the normally closed switch 42 of the first switching means 4, and this state is maintained.

When a high-level control signal is sent from the CPU 7 to the gate circuit 12 by operating the personal computer in order to use the modem 6 while the telephone 3 is in a call state, the gate circuit 12 sends a high-level control signal.

This high level control signal is supplied as a low level signal to the relay 41 forming the first switching means 4 and the relay 51 forming the second switching means 5 via the relay drivers 14A and 14B.

Since the other ends of the relays 41 and 51 are respectively connected to a predetermined DC power source, the relays 41 and 51 are energized by a low level gate signal, and as a result, the normally closed switch 42 of the first switching means 4 is The open state is controlled, the call state is forcibly cut off, and the modem 6 is preferentially connected to the telephone line.

Therefore, in the modem priority function, since the priority switch 15 is in the off state, a high level signal is always supplied to the gate circuit 12, so that the modem 6 can be preferentially connected to the telephone line 1 and personal computer communication is possible. It is possible to prevent accidents such as the loss of important transmission data.

Therefore, when the personal computer communicates with the communication partner through the telephone line via the modem 6, first, the communication partner is confirmed by a call from the telephone 3, and then the personal computer is operated to automatically connect the telephone line to the telephone 3 and the modem 6. Since it is possible to perform personal computer communication by switching between the two, it is possible to avoid erroneous recognition of the communication partner, and the troublesomeness of switching the telephone 3 with the personal computer is eliminated and the operability is improved.

[Advantage of Invention] In this invention, the first use priority function prohibits the interruption of the modem while the telephone is in use, and conversely, the telephone can be used while the modem is in use. Disappear.

With the modem priority function, the modem can be preferentially connected to the telephone line even when the telephone is in use.

Furthermore, by providing a priority switch that can be operated manually, the user can arbitrarily select the first use priority function and the modem priority function according to the purpose of use, which is very convenient, and the simple circuit including the switch can be used. Since this function can be realized, a low-cost telephone line switching circuit can be provided.

[Brief description of drawings]

 The figure is a diagram showing an example of the configuration of the present invention. 1 ... telephone line 3 ... telephone 4 ... first switching means 5 ... second switching means 6 ... modem 11 ... control means 15 ... priority switch

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Claims (1)

[Scope of utility model registration request] 1. A telephone line switching circuit which uses a single telephone line and switches between a telephone and a modem, and comprises a switch for connecting the telephone to the telephone line and a relay for controlling this switch. A first switching means, a second switching means composed of a switch for connecting the modem to a telephone line and a relay for controlling the switch, an off-hook detecting means for detecting an off-hook of the telephone, and an off-hook detecting means. Control means for controlling each switching via the relay of the first and second switching means based on the signal and the signal from the controller of the modem, and for manual operation for enabling or disabling the off-hook detecting means And the off-hook means is enabled by the priority switch. The first-use priority function, which prohibits the modem from being connected to the telephone line based on the off-hook signal from the off-hook detection means when using the telephone, and based on the control signal obtained from the modem side when using the modem With the modem priority function in which the control means operates so as to prohibit the telephone from being connected to the telephone line and the off-hook detection means is disabled by the priority switch, the modem is given priority even when the telephone is in use. Then, the telephone circuit switching circuit is characterized in that the control means is operated so as to be connected to a telephone line.