JP2632109B2 - Facsimile machine - 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 machine.

[0002]

2. Description of the Related Art Generally, in a facsimile apparatus, communication is performed via a modem (hereinafter referred to as a "modem"). Training of a modem is performed prior to communication of image information. If the transmission is performed at the transmission speed of the modem and the telephone line is in poor condition and the training is abnormal, reduce the transmission speed of the modem and perform training again. A so-called fallback function for automatically lowering is provided (for example, see Japanese Patent Publication No. 58-16668).

[0003]

When the signal is greatly attenuated in the case of long-distance communication or the like and the signal level of the received signal is near the limit value of the receiving sensitivity, even if the training of the modem is normal, even if it is normal. When the reception of image information is started, a decoding error of reception is likely to occur due to the magnetic field noise of the drive motor or the noise of the thermal head power supply, and the image information is not normally received.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and includes a means for detecting a signal level of a received signal and a training abnormal signal when the detected signal level is lower than a predetermined level. It is configured by means for returning.

[0005]

Since the present invention is constructed as described above, if the signal level of the received signal is weak and is near the limit of the receiving sensitivity, the abnormal training signal is returned even if the training of the modem is normal. Since the transmission starts by lowering the transmission speed of the modem on the transmitting side, it is less susceptible to noise and can normally receive image information without occurrence of decoding errors.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a facsimile apparatus according to the present invention. (1) is a control device for controlling the entire facsimile apparatus, which is constituted by a microprocessor and has a program memory in which a processing program is stored. Each part is controlled according to the program of (2). The control device (1) performs signal processing of the read transmission original data and processing of the received signal, and generates various control signals. A reading unit (3) optically reads a transmission document, converts the read black-and-white data into an electric signal, and supplies the signal to the control unit (1). The reading unit includes a document transfer mechanism, an illumination mechanism, an image sensor, and the like. . (4) a recording unit for printing by driving a recording head such as a thermal head under the control of the control device (1) based on the received signal;
It comprises a recording paper, a recording paper transport mechanism, and a recording head. Reference numeral (5) denotes a data memory for storing original data read by the reading unit (3) or data subjected to signal processing, and the writing and reading of data are controlled by the control unit (1).

[0008] (6) is a keyboard composed of a communication key, a telephone key, a selection key or a numeric keypad. Control. (7)
Is a display for displaying data and the like input from the keyboard (6), and is constituted by a dot matrix type liquid crystal display. (8) is a modem that modulates a signal transmitted to the telephone line (L) and demodulates a received signal.
s, 7200 bps, 4800 bps, 2400 bps
And the control device (1) sets the transmission speed appropriately. (9) is a signal level detection circuit for detecting the signal level of the received signal, and outputs a detection signal to the control device (1) when the detected signal level is equal to or lower than a preset signal level. Reference numeral (10) denotes a line switching circuit for switching the telephone (11) and the modem (8) to and connected to the telephone line (L), which is constituted by a relay circuit and controlled by the control device (1).

Next, the operation of the present invention having the above configuration will be described.

First, when a line is connected from the transmitting facsimile apparatus to the receiving facsimile apparatus for facsimile communication, a predetermined control signal defined by the standard is transmitted and received between the transmitting and receiving modems as shown in FIG. (8)
After the transmission speed and various operation modes are set, the training signal (TR) is transmitted from the transmission side to the reception side, and the modem (8) is trained. At this time, on the receiving side, the signal level detecting circuit (9) judges whether the level of the received signal is higher than a preset level, and the training of the modem (8) is normal and the received signal level is also predetermined. If the value is equal to or more than the value, the receiving side transmits a CFR signal indicating the reception preparation OK to the transmitting side. As a result, on the transmitting side, the reading unit (3) starts reading the original, performs predetermined signal processing such as encoding, and then sets the transmission speed of the modem (8) set as a result of transmission and reception of control signals between transmission and reception. Is transmitted to the receiving side as image information (PIX).

However, if the training of the modem (8) is abnormal or the received signal level is lower than the predetermined value level, an FTT signal indicating an abnormal training is transmitted from the receiving side to the transmitting side as shown in FIG. I do.
On the transmitting side receiving the FTT signal, the transmission speed of the modem (8) is set to a speed one step lower than the currently set speed, and the set content is transmitted to the receiving side by the DCS signal. A training signal (TR) is transmitted so as to train the modem (8) again at the speed. As a result, if the training is normal and the signal level is equal to or higher than the predetermined level, the CF
The R signal is transmitted to the transmission side, and transmission of image information is started. However, if the reduced transmission speed does not work,
The FTT signal is transmitted from the receiving side, and the transmitting side further reduces the transmission speed of the one-stage modem (8) and performs training again. In this way, the training is repeated until the training is normal and the signal level becomes equal to or higher than the predetermined level.

Therefore, in the conventional communication in which the strength of the reception signal level is not detected, even if the reception signal level is weak and the reception sensitivity is near the limit, if the training of the modem is normal, the transmission of the image information is started. Therefore, an error is likely to occur due to the influence of noise or the like. However, according to the present invention, since both the training and the received signal level are checked, the occurrence of the error can be reduced.

[0013]

As described above, the facsimile apparatus of the present invention is provided with means for detecting the signal level of a received signal, and when the signal level is lower than a predetermined level, instructs the transmitting side to decrease the transmission speed of the modem. As a result, reception near the limit value of the reception sensitivity is lost, and occurrence of an error can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a facsimile apparatus of the present invention.

FIG. 2 is a schematic diagram showing a transmission signal of the facsimile apparatus of FIG.

FIG. 3 is a schematic diagram showing a transmission signal of the facsimile apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control device 3 Reading part 4 Recording part 8 Modem 9 Signal level detection circuit

Claims (1)

(57) [Claims] In a facsimile apparatus which performs communication via a modem, means for training a modem by transmitting a training signal, means for detecting a signal level of a received signal, and a means for detecting a signal level of the training signal in advance. A facsimile apparatus comprising control means for instructing to reduce the transmission speed of a modem when the level is lower than a predetermined level.