JP3323657B2 - Network controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network controller for selectively connecting a telephone to a telephone line.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a conventional circuit.

[0003] The contact position of each relay indicates a standby state.

[0004]

[Problems that the Invention is to Solve In this state, using an external phone, H relay via the CML relay, when a call pulse dialing, capacitor included in the call signal detecting circuit (usually 0 .1 μF to 2 μF), the waveform of the pulse dial is distorted.

[0005]

In order to achieve the above object, the present invention uses a two-contact circuit relay as an S relay,
It is characterized in that one contact is connected in the same manner as in the prior art, and the other contact is connected in series with the call signal detection circuit.

In the above configuration, the two contacts are operated in conjunction with each other. When the off-hook of the external telephone is detected, S
Activate the relay, disconnect the call signal detection circuit,
The ringing signal detection circuit does not adversely affect the dial pulse transmitted from the external telephone.

Further, the shape (dimensions) of the S relay of the one-contact circuit shown in the conventional example and the relay of the two-contact circuit used in the present invention are almost the same, as compared with the case where another relay is newly used. Substrate space can be saved.

Further, in terms of cost, the use of the S-relay of the two-contact circuit type can be suppressed sufficiently lower than the increase in cost.

In addition, since the relay which has been conventionally used is diverted, it is not necessary to newly add a control signal line, and this point also has an effect of reducing the load on the board design.

[0010]

FIG. 1 is a block diagram of a network control circuit of a facsimile communication apparatus embodying the present invention. In FIG. 1, reference numeral 1 denotes an off-hook detection unit for detecting an off-hook of an external telephone;
2 is an H relay for switching the connection of the external telephone to a line or an external DC (direct current) applying power source 3, 3 is an external DC applying power source, 4 is a call signal detecting circuit, 4a determines a level threshold value of an input call signal. Bidirectional Zener diodes, 4b and 4c, a resistor and a capacitor, respectively, which determine the impedance to a calling signal, 5 a CML relay for switching the line to an external telephone or a modem, 6 a P relay for generating a dial pulse, and 7 a P
S relay that disconnects the subsequent circuit while the relay 6 is operating,
7a and 7b are the contacts of the S relay, 8 is the primary side and 2
Transformer for separating the next side, 9 is 2-wire to 4-wire conversion, 10 is a modem, 11 is a CPU (central processing unit) for controlling this circuit, and 12 is a ROM in which a software program for controlling this circuit is stored. .

Next, an embodiment of the present invention will be described in detail with reference to FIG.

First, in the standby state, the contacts of each relay are in the following state. That is, CML relay 5
Is the external telephone side, H relay 2 is the line side, P relay 6
Is open, contacts a and b of S relay 7 are closed
In a closed state. Here, when the external telephone connected to T1 and T2 is off-hook, the off-hook detection unit 1 detects that fact and the CPU 11 operates the S relay 7. At this time, the contact 7b of the S relay is connected to the calling signal detection circuit 4
Move in the direction to separate. The contact 7a also operates at the same time,
Since it is separated from the line by the CML relay 5, it does not affect peripheral circuits. Note that the external telephone is
CML relay 5, H relay 2, P relay
6 remains in the same state as the standby state.

Next, there is a CML relay 5 on the modem side,
The H relay 2 is switched to the DC power supply 3 side except during dialing or communication from the facsimile main body, and supplies DC power to an external telephone to enable off-hook detection. Here, when the off-hook detecting unit 1 detects an off-hook of the external telephone, the CPU 11 first switches the H relay 2 to the line side, then switches the CML relay 5 to the external telephone side, and finally operates the S relay 7. , The call signal detection circuit 4 is disconnected.

Next, when the P relay 6 generates a dial pulse, the contact 7a of the S relay 7 is open and the CML relay 5 is switched to the modem side. The H relay 2 is connected to the DC application circuit 3 side,
DC power can be supplied to the external telephone. What
The contact 7b of the S relay 7 is also in the open state.

As described above, in each case, the use of the S relay can prevent the dial pulse transmitted from the external telephone from being distorted by the capacitor 4C of the call signal detection circuit 4.

Here, as the S relay, a mechanical relay having a low on-resistance is desirable, but a semiconductor relay (photo)
It is also possible to use an o-MOS relay or the like.

The off-hook detecting section 1 may be a mechanical switch linked to a hook switch in addition to the current sensor.

[0018]

As described above, according to the present invention,
By making the S relay a two-contact circuit, it is possible to minimize cost increase, effectively use board space, and prevent dial pulse distortion.

[Brief description of the drawings]

FIG. 1 is a block diagram of a network control device embodying the present invention.

FIG. 2 is a block diagram of a conventional network control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Off-hook detection part 4 Call signal detection circuit 5 CML relay 6 P relay 7 S relay 10 Modem 11 CPU

Claims (3)

(57) [Claims] 1. A network control device for connecting a telephone to a line, a connection means for connecting one of the telephone and the modem to the line, a call signal detection means, and a connection between the connection means and the modem. Dial pulse generating means, and relay means having two circuit contacts, one contact of the relay means is connected between the modem and the dial pulse generating means, and the other contact of the relay means and the call A signal detecting means is connected in series to the telephone side of the connecting means, and the one contact of the relay means disconnects the modem from the line when the dial pulse generating means is generating a dial pulse. Switching, the other contact of the relay means disconnects the call signal detection means from the line when the telephone goes off-hook. Ri network control apparatus characterized by switched. 2. A network control device for selectively connecting a telephone and a communication means to a line, a switching means for switching a line to a telephone or a communication means, a call signal detecting means, the switching means and the communication means. And a relay means having two circuit contacts, wherein one contact of the relay means is connected between the communication means and the dial pulse generating means, and wherein the relay means The other contact and the call signal detecting means are connected in series to the telephone side of the switching means, and the one contact of the relay means is provided when the dial pulse generating means generates a dial pulse. The communication means is switched to disconnect from the line, and the other contact of the relay means detects the call signal when the telephone goes off-hook. Network control apparatus characterized by switching to as disconnecting means from the line. 3. A modem, connection means for connecting one of the telephone and the modem to a line, call signal detection means,
Dial pulse generating means connected between the connection means and the modem, and relay means having two circuit contacts, one of the contacts of the relay means being connected between the modem and the dial pulse generating means The other contact of the relay means and the call signal detection means are connected in series to the telephone side of the connection means, and the one contact of the relay means is such that the dial pulse generation means generates a dial pulse. When the telephone is off-hook, the other contact of the relay means is switched to disconnect the call signal detection means from the line. Facsimile communication device.