JPH0644204Y2 - Telephone line busy display with resonance prevention function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a device for preventing interference between terminal devices which occurs when a plurality of communication terminal devices are connected to an outside line of one telephone line.

[Prior Art] A plurality of communication terminal devices, such as a facsimile machine and a business phone, may be used by being connected to an outside line of one telephone line. In this case, when one communication terminal device is in use or is about to be used, interference may occur with the other communication terminal device, but this interference is prevented from the viewpoint of improving service. Need to

For example, when a facsimile machine and a business phone are connected to one outside line and the facsimile machine is in use, it is necessary to display to the business phone that the line is in use. It is necessary to prevent the business phone from resonating when making a call.

[Problems to be Solved by the Invention] By the way, some facsimile machines output a signal indicating that the facsimile machine is in use.
Some have terminals (busy tone terminals). If you connect a facsimile machine equipped with a BT terminal to the outside line of 1 together with the business phone, the fact that the facsimile machine is in use is displayed on the business phone, but if the outside line is a dial line. Has a problem that the business phone at the bottom resonates when dialed by a facsimile machine.

In addition to the problem of resonance when a facsimile machine without a BT terminal and a business phone are connected by a first outside line, the facsimile machine is not equipped with a BT terminal, so the facsimile machine is in use. There is a problem that the fact that is is not displayed on the business phone.

Even when the cordless phone connection device and the business phone are connected by an outside line, there is a problem that resonance occurs when calling from the cordless phone cordless handset, and the cordless phone connection device is not equipped with a BT terminal, so the cordless phone is in use. There is a problem that the message is not displayed on the business phone.

On the other hand, in order to prevent resonance, if the business phone and the facsimile machine are branched through a branch type converter (for example, MJ converter-B) and connected by an outside line of 1, the resonance can be prevented. Since it is completely confidential, another problem occurs that the facsimile device cannot be remotely activated from the business phone side. The remote activation is to activate the facsimile device by sending a specific signal from a telephone connected to the outside without pressing the communication start button of the facsimile device.

The present invention connects a facsimile device, a cordless phone connecting device, etc. to an outside line, and connects a business phone, a home telephone, etc. to the lower part thereof, and prevents the business phone and the home telephone from resonating when dialing the facsimile device, the cordless phone. It is an object of the present invention to provide an outside line busy indicator with a resonance prevention function that can indicate that a facsimile machine or a cordless phone is in use.

[Means for Solving the Problems] According to the present invention, when connecting a second external connection device to a lower portion of a first external connection device, a first loop detection circuit is connected between an external line of a telephone line and the first external connection device. A second loop detection circuit is connected between the first external connection device and the second external connection device, and a line disconnection circuit is connected between the second loop detection circuit and the second external connection device. A line-in-use display output circuit that outputs a signal indicating that the outside line connection device is off-hook to the second outside connection device is provided, and the first loop detection circuit detects the loop state of the outside line and the second loop detection circuit When the loop state of the outside line is not detected, the line disconnection circuit is operated and the line busy display output circuit is operated.

[Operation] The present invention operates the line disconnection circuit when the first loop detection circuit detects DC loop formation and the second loop detection circuit does not detect DC loop formation.
When the external connection device is dialed, the second external connection device is disconnected from the first external connection device, resonance does not occur in the second external connection device, and at that time, the line in-use display output circuit operates. Therefore, when connecting a fax machine without a BT output terminal and a cordless phone connection device to the outside line and connecting a business phone and a home telephone underneath, make sure that the business device and the home telephone are in use. Can be displayed.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention.

In this embodiment, a facsimile device 1 is connected to an outside line L of the telephone line via a telephone line busy display (hereinafter referred to as a display) 3 with a resonance prevention function, and the facsimile device 1 is connected via the display 3. Business phone 2 is connected to the bottom.

The display 3 includes a first loop detection circuit 10, a second loop detection circuit 20, a line disconnection circuit 30, and a line in-use display output circuit.
40 and a control circuit 50.

The first loop detection circuit 10 includes an external line L and a facsimile device 1.
Is a circuit that is connected between the facsimile machine 1 and the facsimile machine 1 and detects that the facsimile machine 1 forms a DC loop. The first loop detection circuit 10 is composed of a relay, and recognizes that a DC loop is formed by detecting that a DC current flows through the external line L. Of course, the fact that the DC loop is formed may be detected by something other than the relay. Further, the first loop detection circuit 10 has a low impedance with respect to a signal such as a voice, and therefore,
The DC resistance value is a few without hindering the signal transmission.
It is 10Ω or less, does not hinder the signal operation of the external line L, continues the polarity reversal operation of the external line L, and normally transmits the inverted signal to the terminal side device. Furthermore, the impedance is low even for a call signal of 16 Hz, and even if a 16 Hz signal is received, it is not recognized that a DC loop is formed. Also,
The outer wire and ground are insulated and have a withstand voltage of 1KV or more.

The second loop detection circuit 20 is a circuit that is connected between the facsimile device 1 and the business phone 2 and detects that the business phone 2 forms a DC loop. This second
The specific configuration of the loop detection circuit 20 is similar to that of the first loop detection circuit 10.

The line disconnection circuit 30 is a circuit that is connected between the second loop detection circuit and the business phone 2 to disconnect the line, and is composed of a contact of a relay provided in the control circuit 50.

The line-in-use display output circuit 40 is a circuit that outputs a loop signal indicating that the facsimile apparatus 1 is off-hook (forming a DC loop) to the business phone 2 and a display lamp such as an LED (not shown).

The control circuit 50 operates the line disconnection circuit 30 and outputs a line busy display when the first loop detection circuit 10 detects the DC loop formation and the second loop detection circuit 20 does not detect the DC loop formation. This is a circuit for operating the circuit 40.

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

First, when both the facsimile device 1 and the business phone 2 are on-hook, since no DC loop is formed, neither the first loop detection circuit 10 nor the second loop detection circuit 20 outputs a loop detection signal. Therefore, the control circuit 50 does not send a signal for disconnecting the line to the line disconnecting circuit 30 and does not perform control for outputting a loop signal to the line-in-use display output circuit 40.

Here, if the facsimile device 1 is off-hooked without the business phone 2 being off-hooked, a direct current loop is formed in the facsimile device 1, so that the first loop detection circuit 10 outputs a loop detection signal and the second loop detection circuit 20 loops. Does not output the detection signal. For this reason, the control circuit 50 sends a signal for disconnecting the line to the line disconnecting circuit 30, and the business phone 2 is disconnected from the outside line L. Therefore, when dialing the facsimile device, resonance does not occur in the business phone 2. At that time, since the control circuit 50 controls the line-in-use display output circuit 40 to output a loop signal, even if the facsimile machine 1 does not have a BT output terminal, the facsimile machine 1 It can be surely displayed on the business phone 2 that is being used. At the same time, a display lamp such as an LED (not shown) is turned on to visually confirm that the facsimile apparatus 1 is in use.

On the other hand, if the business phone 2 is off-hook before the facsimile device 1 is off-hook, the first loop detection circuit
Both 10 and the second loop detection circuit 20 output a loop detection signal. For this reason, the control circuit 50 does not send a signal for disconnecting the line to the line disconnecting circuit 30, so that the business phone 2 can talk with the other party. Further, the line-in-use display output circuit 40 does not output a loop signal.

Further, when the MJ converter-B or the like is used, it is completely confidential and therefore the remote activation signal cannot be transmitted from the business phone to the facsimile device. However, in the above embodiment, the remote activation signal is transmitted from the business phone 2 to the facsimile device 1. can do.

In the above embodiment, the facsimile device 1 is an example of the first external connection device, but a cordless phone connection device may be used instead, and the business phone 2 is the second external connection device.
Although an example of the external connection device, a home telephone may be used instead.

According to the present invention, when the first external connection device is dialed, the second external connection device is disconnected from the first external connection device, so that resonance does not occur in the second external connection device. Further, at that time, there is an effect that the second external connection device or the user can be surely displayed that the first external connection device is in use.

[Brief description of drawings]

 FIG. 1 is a block diagram showing an embodiment of the present invention. 3 ... Telephone line in-use indicator with resonance prevention function, 10 ... First loop detection circuit, 20 ... Second loop detection circuit, 30 ... Line disconnection circuit, 40 ... Line in-use display output circuit, 50 ... Control circuit.

Claims (1)

[Scope of utility model registration request] 1. A first loop detection circuit which is connected between an external line of a telephone line and a first external connection device and detects that the first external connection device side forms a DC loop; A second loop detection connected between a second external connection device connected to a lower part of the external connection device and the first external connection device, and detecting that the second external connection device forms a DC loop. A circuit; a line disconnection circuit connected between the second loop detection circuit and the second external connection device to disconnect the line; and a signal indicating that the first external line connection device forms a DC loop. A line-in-use display output circuit for outputting to the second external connection device; and when the first loop detection circuit detects DC loop formation and the second loop detection circuit does not detect DC loop formation, Operates the above line disconnection circuit An external line busy indicator with a resonance prevention function, which has a control circuit for operating the above-mentioned line busy display output circuit.