JP3199671B2 - Facsimile modem - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile modem for executing a telephone network facsimile communication under the control of a built-in microcomputer.

[0002]

2. Description of the Related Art Conventional facsimile modems of this type are:
It has line switching means for hooking off / on the telephone line, modulation / demodulation processing means, serial data I / F (interface), and a built-in microcomputer for centrally managing and controlling the operation of each unit. Below, it is configured to execute telephone network facsimile communication by the telephone line.

[0003]

However, in this type of facsimile modem, when the built-in microcomputer goes out of control during communication, even if the communication partner terminal performs hook-on (line disconnection), it responds accordingly. The hook-on operation of the own station is not performed, and as a result, a problem arises in that the telephone line is kept in a talk state.

An object of the present invention is to provide a facsimile modem capable of reliably preventing a telephone line from being held in a talk state due to a runaway of a built-in microcomputer.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a line switching means for hooking off / on a telephone line under the control of a built-in microcomputer, and the line switching means under the control of the microcomputer. Facsimile communication means for executing telephone network facsimile communication via a telephone line, means for detecting a busy tone received when a communication partner terminal disconnects the line, and counting the number of times detected by the busy tone detection means and setting the counted value to a predetermined value A counter for forcibly resetting the microcomputer by generating a reset signal when the value reaches a value, and when the communication partner terminal disconnects the line, regardless of runaway of the built-in microcomputer, the built-in microcomputer And reset the phone line to automatically hook on the telephone line. It is intended.

As a result, a facsimile modem which can reliably prevent the telephone line from being held in a talk state due to the runaway of the built-in microcomputer can be obtained.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a line switching means for performing a hook-off / on of a telephone line under the control of a built-in microcomputer, and the telephone line under the control of the microcomputer. Facsimile communication means for executing telephone network facsimile communication, means for detecting a busy tone received when a communication partner terminal disconnects the line, and counting the number of times the busy tone detection means detects the count, and the count value becomes a predetermined value And a counter for forcibly resetting the microcomputer by generating a reset signal when the counter reaches the limit, whereby the telephone line is kept in a talk state by the runaway of the built-in microcomputer. That is, the effect of reliably preventing the occurrence can be obtained.

According to a second aspect of the present invention, in the first aspect, a power-on reset circuit for generating a reset signal when the power is turned on, and the number of detections by the busy tone detecting means are counted, and the counted value reaches a predetermined value. And a logic circuit for resetting the microcomputer with a logical sum of the two reset signals.
An effect is obtained that the microcomputer can be reset both in the case where the microcomputer runs away and when the power is turned on.

According to a third aspect of the present invention, in the first or second aspect, a power-on reset circuit for generating a reset signal for the built-in microcomputer when the power is turned on, and the number of times of detection by the busy tone detecting means are counted and counted. And a counter that generates a reset signal of the microcomputer when a predetermined value is reached, and the counter content is initialized by a reset signal generated by the power-on reset circuit. As a result, an effect is obtained that the reset preparation state when the microcomputer runs out of control can be prepared every power-on.

[0010] The invention described in claim 4 is the invention according to claims 1 to 3.
In any one of the above, a counter for counting the number of times of detection of the busy tone detecting means and generating a reset signal of the built-in microcomputer when the counted value reaches a predetermined value, and when the microcomputer is reset, This is characterized in that the counting content of the counter is initialized, whereby the operation of always preparing the reset preparation state when the microcomputer runs out of control can be obtained.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 1 shows an embodiment of a facsimile modem to which the technology of the present invention is applied.

In FIG. 1, L is a telephone line, 1 is a facsimile modem according to the present invention, and 3 is a data terminal (a personal computer).

The facsimile modem 1 has a modular jack 11 for connecting the line L, and line switching circuits 12 and 16H for hooking off / on (connecting / disconnecting) the line L.
z, a line signal transformer 14, a modulation / demodulation processing unit 15, and a serial I / F (RS
232C) control unit 16, serial connector 17, memory 18, built-in microcomputer (CPU) 19, power-on reset circuit 20, busy tone detection circuit 2
1, a counter 22, an OR logic circuit 23 and the like.

Here, the built-in microcomputer 19
Executes facsimile communication control according to a predetermined communication control procedure in response to an incoming call detection output by the call signal detection circuit 13 or a command from the data terminal 3;
The operation of the line switching circuit 12 and the modulation / demodulation processing unit 15 is controlled. Hook off / on operation by line switching circuit 12, facsimile communication by telephone line L, serial I / O
The exchange of data / commands with the data terminal 3 by the F control unit 16 is performed under the control of the built-in microcomputer 19.

The power-on reset circuit 20 generates a reset signal d for the built-in microcomputer 19 when the power is turned on.

The busy tone detection circuit 21 outputs a line signal a
Is constantly monitored to detect a busy tone received when the communication partner terminal disconnects (hook-on). This detection output b is input to a counter 22 described later.

The counter 22 uses the detection output b to calculate
The number of times of detection by the busy tone detecting circuit 21 is counted, and a count-up signal (carry or borrow) when the counted value reaches a predetermined value (for example, four times) is given to the microcomputer 19 as a reset signal c. In this embodiment, the count content of the counter 22 is initialized by a reset signal d generated by the power-on reset circuit 20.

The OR logic circuit 23 supplies a logical sum output (c / d) of a reset signal d generated by the power-on reset circuit 20 and a reset signal c generated by the counter 22 to a reset terminal of the microcomputer 19.

FIG. 2 is a waveform chart showing an operation example of the facsimile modem shown in FIG. In FIGS. 1 and 2, facsimile communication is performed after hook-off (line connection) by the line switching circuit 12. When this communication ends and the other terminal hooks on (line disconnection), the telephone line L is switched. A busy tone from the station appears as line signal a.

Here, if the microcomputer 19 continues to operate normally, the facsimile communication is terminated.
A predetermined termination procedure is executed by the microcomputer 19, and the hook-on (line disconnection) of the own station should be executed by this termination procedure. However, if the microcomputer 19 falls into a runaway state for some reason, the predetermined termination procedure is not executed, and the hook-off state is maintained even after the communication ends and the partner terminal hooks on.

If the other terminal remains hooked off after hooking on, a busy tone appearing on the line L is detected, and the detection output b is counted by the counter 22. This count value is a preset value (for example, 4)
, The counter 22 outputs a count-up signal. This count-up signal is supplied to a reset terminal of the microcomputer 19 as a reset signal c. Thus, the microcomputer 20 is forcibly reset. With this forced reset, the microcomputer 19 restarts from the initial state, and executes the control for switching the line switching circuit 12 to the hook-on (line disconnection) state by the processing after this restart.

As described above, when the communication partner terminal is disconnected, regardless of the runaway of the built-in microcomputer 19, the built-in microcomputer 19
And the telephone line L can be automatically hooked on. As a result, it is possible to reliably prevent the telephone line from being kept in a talk state due to a runaway of the built-in microcomputer.

FIG. 3 shows another embodiment of the facsimile modem according to the present invention. The facsimile modem shown in the figure is basically the same as the above-described embodiment, except for the method of initializing the counter 21 for generating the reset signal c.

That is, when the built-in microcomputer is reset, the reset signal c (or d)
To the reset terminal (clear terminal) of the counter 21 via the delay circuit 24,
Is initialized.

Thus, the built-in microcomputer 1
Each time 9 is reset, the counter 22 is initialized,
The next runaway of the microcomputer 19 can be prepared.

In the above description, the facsimile communication has been described. However, data communication by a facsimile modem having a data communication function can be similarly performed.

[0027]

As described above, according to the present invention, it is possible to obtain a facsimile modem capable of reliably preventing a telephone line from being held in a talk state due to a runaway of a built-in microcomputer. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a facsimile modem to which the technology of the present invention is applied.

FIG. 2 is a waveform chart showing an operation example of the facsimile modem shown in FIG.

FIG. 3 is a block diagram showing another embodiment of the facsimile modem according to the present invention.

[Explanation of symbols]

 L telephone line 1 facsimile modem according to the present invention 3 data terminal (personal computer) 11 modular jack 12 line switching circuit 13 call signal detection unit 14 line transformer 15 modulation / demodulation processing unit 16 serial I / F (RS232C) control unit 17 serial connector 18 Memory 19 Built-in microcomputer (CPU) 20 Power-on reset circuit 21 Busy tone detection circuit 22 Counter 23 OR logic circuit 24 Delay circuit a Line signal b Busy tone detection output c Reset signal (busy tone) d Reset signal (power on)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04M 11/00-11/10 H04N 1/00 H04N 1/32-1/36 H04N 1/42-1 / 44

Claims (4)

(57) [Claims] Communication means for performing hook-off / on of a telephone line under the control of a built-in microcomputer, facsimile communication means for executing telephone network facsimile communication by the telephone line under the control of the microcomputer, Means for detecting a busy tone received when the partner terminal disconnects the line; counting the number of detections by the busy tone detecting means; generating a reset signal when the counted value reaches a predetermined value; A facsimile modem comprising a counter for forcibly resetting. 2. A power-on reset circuit for generating a reset signal when the power is turned on, a counter for counting the number of times of detection by the busy tone detecting means, and generating a reset signal when the counted value reaches a predetermined value. 2. A facsimile modem according to claim 1, further comprising a logic circuit for resetting said microcomputer by a logical sum of two reset signals. 3. A power-on reset circuit for generating a reset signal for a built-in microcomputer at power-on,
A counter for counting the number of times of detection by the busy tone detecting means and generating a reset signal of the microcomputer when the counted value reaches a predetermined value, and a reset signal generated by the power-on reset circuit. 3. The facsimile modem according to claim 1, wherein the counting contents are initialized. 4. A counter for counting the number of times of detection by the busy tone detecting means and generating a reset signal for a built-in microcomputer when the counted value reaches a predetermined value, and when the microcomputer is reset, 4. The facsimile modem according to claim 1, wherein the content of the counter is initialized.