JPS63294048A - Communication equipment - Google Patents

Abstract

PURPOSE:To prevent leak of information and the malfunction due to line acquisition by superposing the use condition of a line by a superposing means and controlling line acquisition based on the supervisory result. CONSTITUTION:When a terminal equipment is hooked off at the time of incoming, an off-hook detector 9 reports off-hook to a controller 10. The controller 10 controls a line connection equipment 5 to connect the line because the line is not used and off-hook is reported. If another terminal equipment 15 uses the line at the time of originating a call, the controller 10 prevents the equipment 5 from connecting the line. At this time, no sounds are emitted from a receiver 7 because the line is not connected. Since this silence reports that the equipment 15 uses the line, a display equipment 11 detects the signal from a line check equipment 8 to indicate it with an LED, an LCD, a buzzer, or the like that the line is used by the terminal equipment 15. Thus, the malfunction of another terminal equipment and wiretapping are prevented because the line is not connected when another terminal equipment uses the line.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a communication device used in a communication system in which a plurality of communication devices are connected in parallel to a communication line.

[Prior Art] Conventionally, parent-child telephones have been known as this type of communication system. In this parent-child telephone, a plurality of telephones are connected in parallel to one line, and each telephone seizes the line by going off-hook.

[Problem that the invention seeks to solve] However,
Although the communication system described above has a simpler configuration than one in which terminals are switched and connected using an exchange, it has the following drawbacks.

(1) In the case of multiple telephones, a conversation on one telephone may be intercepted or intercepted on the other telephone.

(2) If a facsimile device and a telephone are connected separately to the same line, if you try to use the telephone while the facsimile device is communicating, the facsimile data changes and communication becomes impossible.

(3) If a personal computer communication modem and a telephone are connected separately to the same line, if you try to use the telephone during communication, the data will change and communication will become impossible.

[Means for Solving the Problems] The present invention monitors the usage status of a line by a monitoring means and controls the line acquisition based on the result.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of this embodiment. In the figure, 1 is a public telephone network to which the telephone of this embodiment is connected, 2 is a bell that notifies you of an incoming call, and 3 and 4 5 is a dial pulse generator for dialing, 5 is a line connection device for connecting the handset to the public telephone network, 6 is a transmitter, 7 is a receiver, and 8 is another terminal 15 connected to the same line. 1 is a line check device that checks whether the line is in use; 9 is an off-hook detection device that detects the hook status; 10 is a control device that controls the line connection device of 5;
1 is a display device indicating that the line is available for use;
12 is a line check signal line, 13 is an off-hook signal line,
14 is a line connection control signal line, and 15 is a terminal connected in parallel to the same line.

First, the time of calling will be explained using FIG. 1. First, pick up the transmitter. Then, the off-hook detection device 9 notifies the control circuit 10 that the hook is off-hook. At this time 1
The control circuit 0 detects the signal from the line check device 8, does not connect the line if the line is being used by the terminal 15, and controls the line connection device 5 only when the line is not in use. Connect. Note that this 8 line check device detects 15 when it detects no signal or a signal other than a calling signal (ring tone).
The terminal determines that the line is in use, and notifies the ten control circuits that the line is in use.

After the line is connected, dialing is performed using a well-known 3.4 dial pulse generator. However, at this time, the line check device 8 detects a dial tone, a busy tone, a ringback tone, and a dial pulse tone. Since this is judged as "the line of terminal 15 is in use," after connecting the line to the line connection device of 5, the control device of 10 ignores the signal from the check device of 8 and disconnects the line. Must be retained.

The signal from the line check device is required only when the line is connected, and is not needed after the line is connected.

FIG. 2 shows an example of a control circuit that realizes the above operation. 1
Reference numeral 2 indicates an input signal from the line check device shown in FIG. 1, which indicates a high level if the line is in use, and a low level if the line is idle. Reference numeral 13 indicates a human input signal from the off-hook detection device 9, which indicates high if off-hook and low if on-hook.

Reference numeral 14 indicates an output signal for controlling the 50-line connection device, which indicates a high level when connected, and indicates a low level when not connected.

14 is high level, that is, the line is tangential to 16 A.
This is a case where 12 is high and 13 is high by the ND circuit, that is, the line is idle and off-hook.

Also, once 14 becomes high level, buffer 15 is in a high impedance state while 14 = high.
The signal at 12 is ignored and 14 is held high until 13 goes low or on-hook. This can be realized using a simple circuit as described above.

Furthermore, if the line check device 8 in FIG. 1 is made not to respond to signals transmitted from the network, such as dial tones and busy tones, the control circuit 10 can be simply an AND circuit. However, the line checking device would be complicated.

Next, the case of an incoming call will be explained using FIG. When there is an incoming call, the line check device 8 is configured not to detect a ring tone, so the connection is made as in normal operation. First, when the off-hook occurs, the off-hook detection device 9 notifies the control device 10 that it is off-hook.

Since the line is unused and the control device is an off-footer, it controls the line connecting device 5 and connects the line.

Further, when the line is being used by the 15th terminal at the time of the call, the control device prevents the 5th line connecting device from connecting the line. At this time, there is no line connection from the receiver of number 7, so there is no sound. This no sound is a notification that 15 terminals are using the line. However, since it is dangerous to use the absence of any sound as a notification, it is necessary to provide the display device 11 shown in FIG. The display device detects No. 48 from the line check device of 8 and turns on the LED.

The LCD, buzzer, etc. will indicate that the line is being used by 15 terminals.

As explained above, if a telephone according to the present invention is used, a line is not connected when another terminal is in use, thereby preventing other terminals from malfunctioning or eavesdropping.

[Other Examples] Although the above-mentioned example shows the case where it is attached to a telephone,
It may be used not only for telephones but also for communication devices that perform data communication such as facsimile machines. In this case, if a modem such as a facsimile machine can be used as a line check device, the cost can be reduced.

As explained above, the telephone set of this embodiment can prevent other terminals connected in parallel to the same line from malfunctioning, or from eavesdropping on or interfering with other telephones.

Furthermore, in the telephone set of this embodiment, priority is given to the telephone that answers first, so it does not matter which of the parallelly connected telephones responds.

[Effects] As described above, according to the present invention, in a communication system in which a plurality of communication devices are connected in parallel to a communication line, malfunctions due to information leakage or line capture can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the telephone of this embodiment, and Fig. 2 is a block diagram of the telephone of this embodiment.
FIG. 2 is a diagram showing an example of a circuit diagram of a control device and a line connection device shown in the figure. 5 is a line connection device, 8 is a line check device, 9 is an off-hook detection device, 10 is a control device, 11 is a display device, 12
13 is a line check signal, 13 is an off-hook signal, 14 is a line connection control signal, and 15 is a terminal device connected in parallel to the same line.

Claims (1)

[Scope of Claims] A communication device used in a communication system in which a plurality of communication devices are connected in parallel to a communication line, comprising: means for monitoring the usage status of the communication line; and means for capturing the communication line; A communication device comprising means for controlling the acquisition means according to usage conditions of a communication line.