JPH02159870A - Facsimile equipment - Google Patents

Abstract

PURPOSE:To prevent interference from being generated by holding a line with plural facsimile equipments by forming a direct current loop and executing transmission and reception only when it is detected that a signal is not transmitted on the line. CONSTITUTION:In correspondence to setting an original to the facsimile equipment and pushing down a transmission key by an operator, a transmission request is generated. Concerning the signal on the line informed from a signal detecting circuit 1, it is detected by a control part 4 for a prescribed time whether the signal is transmitted from the other facsimile equipment or not. Next, it is decided whether the signal exists or not. In the case of YES (when it is decided that the signal is transmitted on the line), the transmission is waited. In the case of NO, during a time (t), it is decided whether the signal exists on the line or not. In the case of YES, normal transmission processing is executed. Namely, the direct current loop of the line is formed by a line switching circuit 2 and operation is set to a transmittable and receivable state. Then, transmission and reception is executed.

Description

[Detailed Description of the Invention] [Summary] Regarding a facsimile device that is connected in parallel to a line to transmit and receive data, if the facsimile device is connected in parallel to the line and no signal is detected from the line for a predetermined period of time, a DC loop is established. The purpose is to prevent the occurrence of multiple holds and interference at the same time by forming a signal to enable transmission and reception, and to detect whether or not a signal is being transmitted on the line. Equipped with a line switching circuit that switches to form a DC loop on the line and switches it to a transmitting/receiving state when a signal is not detected on the line for a predetermined period of time by the detection circuit, and multiple connections are connected in parallel to the line. death,
When the signal detection circuit does not detect a signal, the line switching circuit switches to form a DC loop for transmission and reception.

[Industrial application field]

The present invention relates to a facsimile machine that is connected in parallel to a line and transmits and receives data. It is desired to prevent communication abnormalities caused by facsimile machines connected in parallel on the same telephone line holding the line at the same time.

[Prior art and problems to be solved by the invention] Conventionally, as shown in Fig. 3, multiple facsimile machines are connected in parallel to the same telephone line, and even though one facsimile machine is in communication, other facsimile machines If a facsimile machine holds the telephone line, the impedance to the telephone line becomes too small, causing a mismatch or interference between the sending and receiving signals between the two stations, making it impossible to operate normally. There was a problem with this.

The present invention connects a facsimile machine in parallel to a line, and when no signal is detected from the line for a predetermined period of time, a DC loop is formed and the facsimile machine is set to be ready for transmission and reception. The purpose is to prevent the occurrence of

(Means for solving problems) Means for solving the problem will be explained with reference to FIG.

In FIG. 1, a signal detection circuit 1 is a circuit that detects whether a signal is being transmitted on a line.

The line switching circuit 2 switches the line to form a DC loop when the signal detecting circuit 1 detects no signal on the line for a predetermined period of time, thereby enabling transmission and reception.

[Effect]

As shown in FIG. 1, the present invention, in response to a transmission request,
When the signal detection circuit 1 does not detect a signal on the line for a predetermined period of time, the line switching circuit 2 switches the line to form a DC loop to enable transmission and reception, and performs transmission and reception. There is.

Therefore, when any of the facsimile machines connected in parallel to one line attempts to send a signal, only when it detects that no signal is being transmitted on the line, will it form a DC loop and transmit/receive. This makes it possible to prevent multiple people from holding the line and interference from occurring.

〔Example〕

Next, the configuration and operation of one embodiment of the present invention will be explained in detail using FIGS. 1 and 2.

In FIG. 1, the facsimile machine ill, (2) is
A plurality of facsimile machines are connected in parallel to a telephone line, each consisting of 1, 1-1, 2, 3, 4, etc.

The signal detection transformer 1-1 is connected to the telephone line via a DC cut capacitor C, and has a high impedance (for example, an impedance of 20 Ω) transformer.

The line switching circuit 2 is a circuit that connects the DC loop transformer 3 to the line to form a DC loop and switches to a low impedance (for example, 600Ω).

The control unit 4 performs various controls, including 1. Detecting whether or not a signal is being transmitted on the telephone line by the 1s signal input from the signal detection transformer 1-1,
When it is detected that a signal is not being transmitted on the telephone line in response to a transmission request, the line switching circuit 2 is switched to form a DC loop and switched to a transmitting/receiving state.

Next, the operation of the configuration shown in FIG. 1 will be explained in detail in accordance with the order shown in the flowchart of FIG.

In FIG. 2, ■ indicates that a send δ request is generated.

This indicates a state in which a transmission request is generated in response to, for example, an operator setting a document on a facsimile machine and pressing a transmission key.

(2) performs signal detection processing on the line. This means that the control unit 4 in FIG. 1 detects whether or not the signal on the line notified from the signal detection circuit 1 has not been transmitted from another facsimile machine or the like for a predetermined period of time. ing.

(2) determines whether a signal exists or not. If YES (if it is determined that a signal is being transmitted on the line), the transmission is awaited at ■. If NO, execute ①.

In (2), it is determined whether or not there is no signal on the line for a period of time. In the case of YES, normal transmission processing is performed in (2), that is, the line switching circuit 2 forms a DC loop of the line and sets the line to a transmitting/receiving state, and transmitting/receiving is performed.

As described above, in response to a transmission request, if no signal is detected on the line for a predetermined period of time, a DC loop is formed, the state is set to enable transmission and reception, and the connection is made to the line by transmitting and receiving. This makes it possible to hold multiple facsimile machines simultaneously and prevent interference from occurring.

〔Effect of the invention〕

As explained above, according to the present invention, when one of the facsimile machines connected in parallel to one line attempts to transmit, only when it detects that no signal is being transmitted on the line, Since a configuration is adopted in which transmission and reception are performed by forming a DC loop, it is possible to prevent a line from being held by multiple facsimile machines and interference from occurring.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a flowchart explaining the operation of the present invention, and FIG. 3 is a diagram explaining the prior art. In the figure, ■ is a signal detection circuit, 1-1 is a signal detection transformer, 2 is a line switching circuit, 2-1 is a DC loop transformer,
4 represents a control unit, and C represents a capacitor for cutting direct current.

Claims (1)

[Scope of Claims] A facsimile device that is connected in parallel to a line to transmit and receive data includes a signal detection circuit (1) that detects whether or not a signal is being transmitted on the line; It is equipped with a line switching circuit (2) that switches to form a direct current loop on the line and switches the line to a transmitting/receivable state when no signal is detected on the line for a predetermined period of time, and multiple lines are connected in parallel to the line. A facsimile apparatus characterized in that, when a signal is not detected by the signal detection circuit (1), the line switching circuit (2) switches to form a DC loop and transmits and receives the signal.