JPH0618391B2 - Telephone terminal equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a telephone terminal device having a telephone line holding function.

2. Description of the Related Art In recent years, telephones with a holding function have been remarkably popularized, and the holding function can be incorporated and used not only in a telephone that can connect two or more telephone lines but also in a telephone that can connect one telephone line. It has become.

Hereinafter, a conventional telephone with a holding function as described above will be described with reference to the drawings.

FIG. 2 shows the structure of a conventional telephone with a holding function. In FIG. 2, 1 and 2 are terminals for connecting to a telephone line, and 3
Is a hold switch, 4 is a hold circuit, 5 is a hook switch,
Reference numeral 6 is a telephone main body portion including a dial sending circuit, a sending / receiving circuit, and the like.

The operation of the conventional telephone with hold function configured as above will be described below.

First, when hook switch 5 is turned on (off hook),
The line voltage between the connection terminals 1 and 2 is applied to the telephone main body 6, a line current flows, the telephone line is closed, and a call becomes possible.

When temporarily leaving the telephone in the middle of a call, when the hold switch 3 is pressed, the hold circuit 4 is turned on and the line current also flows to the hold circuit 4. Therefore, even if the hook switch 5 is turned off (on-hook), the line current continues to flow and the telephone line can be held.

Problems to be Solved by the Invention However, in the above configuration, in order to maintain the closed state of the line during the hold, the DC resistances during the call and the hold need to be substantially the same, and the resistance value Is about 200 ~
It is 300Ω. Therefore, the input impedance of the set, which was about 600 Ω during a call, dropped to 200 to 300 Ω, which is the same as the DC resistance when the call was held, and the impedance of the telephone line fell from the other party's side. The sound was loud and discomforting.

Furthermore, in the process of switching from the call state to the hold state,
Since the call circuit and the hold circuit are temporarily connected in parallel to the telephone line, the DC resistance of the set changes in stages, and as a result, the line voltage also changes in stages and clicks on the other party's telephone. It was heard as noise, which was also unpleasant here.

The present invention has been made in view of the above prior art, does not require a special holding circuit other than the circuit of the telephone body, and
(EN) Provided is a telephone terminal device in which a DC resistance and an input impedance do not change in a call state and a hold state, and a side tone does not increase and a switching noise does not occur in a telephone of a partner side.

Means for Solving the Problems In order to solve the above problems, a telephone terminal device of the present invention includes a semiconductor switching element for closing a telephone line and a semiconductor switching element which is closed when a handset goes into an off-hook state. The first hook switch that closes the handset and the second hook switch that detects that the handset is in the off-hook state, and the hold signal that keeps the semiconductor switching device closed according to the command from the hold switch, and outputs the hold The second hook switch is provided with a control unit for stopping the hold signal when the second hook switch detects the off-hook of the handset while outputting the signal.

Operation With this configuration, when the hold switch is pressed in the call state, the semiconductor switching element maintains the closed state even if the hook switch is turned off by the hold signal, and the on-hook state can be temporarily set in the hold state. When it goes off-hook again, the hold signal is stopped based on the signal from the second hook switch, and the hold state is automatically released. Further, it is possible to reduce the size and cost of the device without requiring a special holding circuit other than the telephone body.

Embodiment One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a structure of a main part of a telephone terminal device according to an embodiment of the present invention. In FIG. 1, 1 and 2 are connection terminals to a telephone line, 3 is a hold switch, 5-1 and 5-
Reference numeral 2 is a hook switch that works together.
Reference numeral 6 is a telephone circuit, a telephone circuit network in which a control unit 6-1 including a microcomputer is configured, 7 is a diode bridge, 8, 9, 10, 11, 14, 15, 1
6, 17 and 20 are resistors, 12 and 18 are PNP transistors, and 13 and 19 are NPN transistors. Again 2
Reference numeral 0 denotes a mute circuit which mutes the microphone 21 of the handset (not shown) when the terminal P1 of the control section 6-1 is logic 0.

The operation of the telephone terminal device configured as described above will be described above.

First, when the hook switch 5 is turned on (off-hook), the voltage of the telephone line is the connection terminals 1 and 2 connected to the telephone line, the diode bridge 7, and the hook switch 5-1.
And to the base of the transistor 13 via the resistors 8 and 20. Therefore, a base current flows from the base of the transistor 13 to the emitter, and the collector and the emitter of the transistor 13 are turned on. As a result, resistance 1
A base current flows from the emitter of the transistor 12 to the base through 0, and the transistor 12 is turned on.
As a result, the voltage of the connection terminal 1 telephone line connected to the telephone line is applied to the telephone circuit network 6, the line state flows, the telephone line is closed, and the telephone call becomes possible. In this state, the output terminal P1 of the control section 6-1 is at the logic level 1 and P2 is at the logic level 0. Dial part (not shown)
When is operated, the control section 6-1 alternately sets the output terminal P2 to the logic level 1 according to the dial number to be transmitted.
Therefore, the transistor 19 is turned on because a voltage is applied to the base through the resistor 16, and the transistor 19 is turned on.
The base potential of 3 becomes equal to the emitter potential, the base current stops flowing, and the state is turned off. As a result, the base current of the transistor 12 also stops flowing, the transistor 12 is turned off, and the dial pulse is sent to the telephone line. The resistor 17 is for stabilizing the base potential of the transistor 19.

Next, a case where the telephone line is put on hold will be described. When the hold switch 3 is pressed, the control unit 6-1 outputs the output terminal P
Set 1 to logic level 0. Therefore, the mute circuit 20 mutes the microphone, a base current flows from the emitter of the transistor 18 to the base of the transistor 15 through the resistor 15, and the transistor 13 is turned on, so that a voltage (hold signal) is applied to the base of the transistor 13. Even when the hook switch 5 is turned off (on-hook), the base current of the transistor 13 is continuously supplied from the telephone network 6 (control unit 6-1), so that the transistors 12 and 13 should be kept on. You can hold the telephone line. The resistor 14 is for stabilizing the base potential of the transistor 18.

Subsequently, when the hook switch 5-1 is turned on (off hook), the interlocking hook switch 5-2 is also turned on. When the control unit 6-1 detects this, the output terminal P1 is returned to the logic level 1. Therefore, the transistor 18 is turned off, and the hold signal is not applied to the transistor 13.

In this state, turn off hook switch 5-1 (on hook)
Then, the base current is not supplied from anywhere to the base of the transistor 13, so that the transistor 12 is also turned off and the telephone line is opened. Further, the resistors 9 and 11 stabilize the base potentials of the transistors 12 and 13, respectively, and prevent them from being inadvertently turned on due to noise or the like.

As described above, according to the present invention, the semiconductor switching element for closing the telephone line, the first hook switch for closing the semiconductor switching element when the handset is in the off-hook state, and the handset are in the off-hook state. The second hook switch that detects the situation and the hold signal that keeps the semiconductor switching element closed according to the command from the hold switch are output, and the second hook switch outputs the hold signal while the handset is off-hook. When the hold signal is detected, the hold signal can be stopped, so that the handset can be put on the cradle and put into the on-hook state in the hold state, and the hold state can be automatically released when the handset is off-hook again. , The user does not need to perform any other operation for releasing the hold Become. In addition, since the hold and the release are performed by electronic control, no noise or click sound is generated, and the DC resistance and the input impedance do not change in the call state and the hold state. It is possible to eliminate the increase of side tone and the generation of switching noise, and the practical effect is great.

[Brief description of drawings]

FIG. 1 is a wiring diagram of a telephone terminal device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional telephone with a holding function. 1, 2 ... Connection terminal to telephone line 3 ... Hold switch 5-1, 5-2 ... Hook switch 6 ... Telephone network 6-1 ... Control unit 7 ... Diode bridge 12, 13, 18 , 19 ... Transistor

Claims (1)

[Claims] 1. A first hook switch for closing an input terminal connected to a telephone line, a semiconductor switching element for flowing a line current to close the telephone line, and closing the semiconductor switching element when a handset is in an off-hook state. A second hook switch for detecting that the handset is in an off-hook state, a hold switch for putting the telephone line on hold, and a hold signal for closing the semiconductor switching element in accordance with a command from the hold switch. When the second hook switch detects the off-hook of the handset while the closed state of the semiconductor switching element is maintained regardless of the state of the first hook switch by sending, and the hold signal is output, A telephone terminal device comprising a control unit for stopping a hold signal.