JP2002044402A - Facsimile machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a facsimile machine by which the frequency characteristic of transmission signals can be corrected optimally. SOLUTION: A test signal is generated by a signal generator 18 of the facsimile machine as a calling side. The test signal is transmitted to the facsimile machine as a receiver and the frequency characteristic of the test signal is measured by a frequency-measuring section 16. The frequency characteristic of the test signal are affected by a telephone line network and the facsimile machine as a receiver. The measured frequency characteristics of the test signals are transmitted to the facsimile machine of the calling side. The set level of an equalizer 4 of the facsimile machine of the calling side is corrected according to the measured frequency characteristic, and transmission signal corrected by the equalizer 4 is transmitted. In this way, the influence of the telephone line network and the facsimile machine of the called side can be compensated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile apparatus for correcting frequency characteristics of a communication signal.

[0002]

2. Description of the Related Art As is well known, facsimile communication is performed through a telephone network or the like, so that it is not possible to avoid a change in frequency characteristics of a communication signal due to the influence of the telephone network.

For this reason, in a conventional facsimile apparatus, the frequency characteristic of a transmission signal is appropriately adjusted at the time of shipment from a factory, or a sales person changes the frequency characteristic of the transmission signal when the apparatus is installed. It was adjusted appropriately.

However, the frequency characteristics of a communication signal vary in accordance with the transmission path and transmission distance of the communication signal in a telephone line network. You can't always get the best one.

For example, when a short transmission distance is assumed and the frequency characteristics of a transmission signal are adjusted in accordance with this distance, if the transmission distance becomes long during long-distance communication, the frequency characteristics of the transmission signal on the receiving side deteriorate. . Conversely, when the frequency characteristics of the transmission signal are adjusted assuming a long transmission distance, the frequency characteristics of the transmission signal on the receiving side also deteriorate when the transmission distance decreases during short-range communication.

For this reason, in a "facsimile apparatus" described in Japanese Patent Application Laid-Open No. 4-127773, data for correcting the frequency characteristic of a transmission signal is set in advance for each of a plurality of destinations, and the data is set to correspond to the destination. Select the data you want to
The characteristics of the equalizer are set according to the data, and the frequency characteristics of the transmission signal are corrected by the equalizer, thereby obtaining the optimum frequency characteristics.

Further, in a "facsimile apparatus" described in Japanese Patent Application Laid-Open No. 1-191524, a tone signal is received from a facsimile apparatus of a communication partner through a telephone line network, and the cause of the line network is determined based on the characteristics of the tone signal. Is estimated, and an equalizer is controlled according to the signal distortion, and the frequency characteristic of the transmission signal is optimally corrected by the equalizer.

[0008]

However, in the "facsimile apparatus" described in Japanese Patent Application Laid-Open No. 4-127773, it is necessary to accurately grasp and register data of a large number of destinations in advance. Relying on them required cumbersome work.

Further, the "facsimile apparatus" described in Japanese Patent Laid-Open Publication No. Hei 1-191524 is based on the premise that there is no distortion in the tone signal output from the facsimile apparatus of the communication partner. It was not possible to estimate the signal distortion caused by the device, so that the frequency characteristics of the transmission signal could not be optimally corrected.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and provides a facsimile apparatus which does not require complicated operations and which can optimally correct the frequency characteristics of a transmission signal. The purpose is to:

[0011]

In order to solve the above-mentioned problems, a facsimile apparatus of the present invention transmits a predetermined test signal from a transmitting facsimile apparatus for transmitting an image to a receiving facsimile apparatus for receiving an image. A test signal communication unit that receives the test signal, measures a frequency characteristic of the test signal, and transmits the measurement result to the transmission-side facsimile apparatus.
Equalizer setting means for setting the characteristics of the equalizer for correcting the transmission signal when receiving the measurement result according to the measurement result.

According to the present invention, a test signal is transmitted from a transmitting facsimile apparatus to a receiving facsimile apparatus, and the frequency characteristic of the test signal is measured by the receiving facsimile apparatus. The test signal is distorted when transmitted through the telephone network between the respective facsimile apparatuses, and its frequency characteristic changes depending on the reception characteristic of the receiving facsimile apparatus. Therefore, based on the measurement result of the frequency characteristics of the transmitted test signal, the characteristics of the equalizer of the transmission-side facsimile apparatus are set, and the transmission signal is corrected by the equalizer, thereby distorting the telephone line network and the reception-side facsimile apparatus. Cancels the receiving characteristics of

In the present invention, the test signal is
It includes at least low, medium and high frequency signals.

If the frequency characteristics are measured based on these three types of signals, it is possible to maintain good measurement accuracy and correction accuracy while shortening the measurement time.

Further, in the present invention, the test signal is
It contains signals of four or more frequencies.

As described above, as the types of signals are increased, the measurement accuracy and the correction accuracy are improved.

In the present invention, the test signal is
It is included in the non-standard function setting signal transmitted and received from the transmitting facsimile apparatus to the receiving facsimile apparatus, and the measurement result is included in the non-standard function signal transmitted and received from the receiving facsimile apparatus to the transmitting facsimile apparatus. .

In the existing facsimile machine, the test signal and the measurement result can be transmitted and received by using the non-standard function setting signal and the non-standard function signal.

Further, in the present invention, the test signal is
It is used together with a training signal transmitted and received from the transmitting facsimile machine to the receiving facsimile machine.

In an existing facsimile machine, a training signal can be used as a test signal.

On the other hand, the facsimile apparatus of the present invention transmits test signal transmitting means for transmitting a preset test signal to the other terminal, and transmits a test result indicating the frequency characteristic of the test signal from the other terminal. Equalizer setting means for setting characteristics of an equalizer for correcting a signal in accordance with the measurement result.

According to the present invention, the facsimile apparatus on the transmitting side includes at least test signal transmitting means and equalizer setting means.

Further, the facsimile apparatus of the present invention includes a frequency characteristic measuring means for measuring a frequency characteristic of the test signal when receiving the test signal from the partner terminal, and transmitting the measurement result to the partner terminal. I have.

According to the present invention, the receiving-side facsimile apparatus includes at least frequency characteristic measuring means.

The present invention can be applied to any type of terminal as long as it functions as a facsimile machine.

[0026]

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

FIG. 1 is a block diagram showing an embodiment of the facsimile apparatus of the present invention. As shown in FIG. 1, a facsimile apparatus 1 of the present embodiment includes a network control unit (NC) for controlling connection between the facsimile apparatus 1 and a telephone line network 2.
U) 3, an equalizer 4 for correcting the frequency characteristics of the carrier transmitted through the telephone network 2, an equalizer switching control unit 5 for switching the set level (frequency characteristics) of the equalizer 4, generating a test signal, and the like. A modem 6 that modulates and demodulates a carrier wave according to image data, an image memory 7 that stores image data, a ROM 8 that stores various programs and data tables in advance, and stores a destination telephone number, a management table, and the like. RAM 9, display unit 10 including a liquid crystal display unit and the like, operation unit 11 in which a plurality of operation keys and switches are arranged, document reading unit 12 for reading the image of the document, and printing for recording the image on recording paper An encoding / decoding unit 14 for encoding and decoding image data; and a control unit 15 for controlling the facsimile apparatus 1 in an integrated manner. It is provided.

The equalizer switching control section 5 has a frequency measuring section 16 and a frequency setting section 17. Upon receiving a test signal, which will be described in detail later, the frequency measurement unit 16 measures the frequency characteristics of the test signal and generates data indicating the frequency characteristics.

The frequency setting unit 17 includes a test signal generation unit 1
8 built-in. The test signal generator 18 stores the frequency characteristics of the test signal in advance, and generates and outputs a test signal based on the frequency characteristics. Furthermore,
The frequency setting unit 17 inputs data indicating the frequency characteristics of the test signal, compares the frequency characteristics of the test signal indicated by the data with the frequency characteristics of the test signal stored in advance, and compares the frequency characteristics of the two. Is obtained, and the setting level of the equalizer 4 is switched according to the difference.

Here, for example, when transmitting an image of a document, the image of the document is read by the document reading unit 12, and image data representing the image is coded by the coding / decoding unit 14 and given to the modem 6. Can be The modem 6
The carrier is modulated in accordance with the image data, and the modulated carrier is transmitted to the telephone network 2 through the NCU 3.

Next, when receiving image data, the carrier transmitted through the telephone line network 2 is received by the NCU 3 and input to the modem 6. The modem 6 demodulates the carrier and supplies a demodulated output (image data) to the encoding / decoding unit 14. The encoding / decoding unit 14 decodes the image data and supplies the image data to the printing unit 13. The printing unit 13 records an image represented by the image data on a recording sheet, and discharges the recording sheet.

Now, the facsimile apparatus 1 having such a configuration will be described.
, Facsimile communication is performed according to the procedure shown in FIG. Here, it is assumed that both the calling facsimile machine and the called facsimile machine have the configuration shown in FIG.

First, in the facsimile machine on the calling side, when the telephone number of the communication partner is input by operating the operation unit 11, the telephone number of the communication partner is stored in the RAM 9. Subsequently, when a call is instructed by operating the operation unit 11, the facsimile machine on the calling side is turned off-hook by the NCU 3 and connected to the telephone network 2. Thereafter, a dial signal indicating the telephone number in the RAM 9 is transmitted from the NCU 3 to the telephone line network 2. Thus, the called facsimile machine is called. When the called facsimile machine responds to this call, the calling facsimile machine is connected to the called facsimile machine through the telephone network 2.

Thereafter, the calling tone signal CN is transmitted from the calling facsimile machine to the called facsimile machine.
G is transmitted, and in response to this, the called station identification signal CED, the non-standard function signal NSF,
Calling terminal identification signal CSI and digital identification signal DIS
Are sequentially transmitted.

Here, it is shown that the non-standard function signal NSF has a function of measuring the frequency characteristic of the test signal.

Next, the non-standard function setting signal NSS, the transmitting terminal identification signal TSI, and the digital command signal DCS are sequentially transmitted from the calling-side facsimile apparatus, and subsequently, a test signal is transmitted.

The non-standard function setting signal NSS indicates that a test signal is to be transmitted. Therefore, the called facsimile machine can know in advance that the test signal will be transmitted.

In the facsimile machine on the called side, the frequency characteristic of the test signal is measured by the frequency measuring section 16, data indicating the frequency characteristic is generated, and the data is transmitted.

The facsimile machine on the calling side receives the data indicating the frequency characteristics and
To enter. Upon input of data indicating the frequency characteristics of the test signal, the frequency setting unit 17 compares the frequency characteristics of the test signal indicated by the data with the frequency characteristics of the test signal stored in advance, and compares the frequency characteristics of the two. The setting level of the equalizer 4 is switched according to the difference.

Subsequently, a training check signal TCF is sent from the calling-side facsimile apparatus to the called-side facsimile apparatus. In response to this, the training check signal TCF is received from the called-side facsimile apparatus to the calling-side facsimile apparatus. The preparation confirmation signal CFR is transmitted.

Thereafter, the image data PIX is transmitted from the calling-side facsimile apparatus to the called-side facsimile apparatus. Subsequently, the multi-page signal MPS is transmitted from the calling facsimile machine, and in response to this, the message confirmation signal MCF is transmitted from the called facsimile machine, and the called facsimile machine is sent from the calling facsimile machine. The image data PIX of the next page is transmitted to the device. Further, if communication of another page is repeated, the multi-page signal MPS and the message confirmation signal M
Transmission and reception of CF and transmission and reception of image data PIX are repeated.

When the transmission / reception of the image data is completed,
A procedure end signal EOP is transmitted from the calling facsimile apparatus, and in response to this, a message confirmation signal MCF is transmitted from the called facsimile apparatus, and a disconnection command signal DCN is transmitted from the calling facsimile apparatus. Then, both the calling facsimile machine and the called facsimile machine go into the on-hook state, and the facsimile communication ends.

The control for transmitting and receiving such signals and data is performed by the control unit 15 in both the calling and called facsimile machines.

Next, from the generation of the test signal, the equalizer 4
The process up to the switching of the set level will be described in detail with reference to the flowchart of FIG.

First, in the facsimile apparatus on the calling side, the non-standard function signal NSF is transmitted to the control unit 1 via the NCU 3.
Enter 5 The control unit 15 receives the non-standard function signal NS
If F indicates that it has a function of measuring the frequency characteristics of the test signal, a non-standard function setting signal NSS indicating transmission of the test signal is transmitted to the telephone network 2 via the NCU 3. Then, the control unit 15 activates the test signal generation unit 18 of the frequency setting unit 17, causes the test signal generation unit 18 to generate a test signal, and sends the test signal to the telephone network 2 via the NCU 3. (Step S1).

This test signal has a frequency of 600 Hz, 1200 Hz, 1800 Hz, 24 Hz, for example, as shown in FIG.
It consists of five types of signals of 00 Hz and 3200 Hz, and the levels of these signals are set to be constant.

When the called facsimile apparatus receives the test signal subsequent to the reception of the non-standard function setting signal NSS, the frequency measuring section 16 measures the frequency characteristics of the test signal and transmits data indicating the frequency characteristics. Generate and transmit this data (step S2).

Here, the test signal is distorted when transmitted through the telephone line network 2 or its frequency characteristic changes depending on the reception characteristic of the called facsimile apparatus. For example, as shown in FIG. 5, the level of the signal of each frequency changes and becomes inconsistent, and attenuates particularly in a low frequency band and a high frequency band. Data indicating the frequency characteristics of the test signal indicates the levels of these signals.

In the facsimile machine on the calling side, this data is input to the frequency setting unit 17 via the NCU 3 (step S3). The frequency setting unit 17 compares the frequency characteristic of the test signal indicated by this data with the frequency characteristic of the test signal stored in advance, obtains the difference between the two, and sets the difference so that the difference becomes zero. That is, the setting level of the equalizer 4 is determined so that the frequency characteristic of the test signal received by the called facsimile apparatus matches the frequency characteristic of the test signal stored in advance (step S5). The setting level is switched (step S4).

When the setting level of the equalizer 4 is switched as described above, the frequency setting unit 17 creates an equalizer setting management table 21 as shown in FIG. In the equalizer setting management table 21, the level A of the test signals (five types of signals) generated by the frequency setting unit 17 and the test signals (five types of signals) measured by the called facsimile machine are stored. The level B, the correction level C which is the difference between the level A and the level B, and the set level D of the equalizer 4 for performing the correction of the correction level C are written.

FIG. 7 is a graph showing a frequency characteristic a (corresponding to the level A of the test signal) as a reference of the equalizer 4.
And frequency characteristics d of the equalizer 4 after the correction (corresponding to the set level D).

After correcting the frequency characteristic of the equalizer 4 of the facsimile apparatus on the calling side in this way, the carrier is modulated by the modem 6 according to the image data PIX, the frequency characteristic of the carrier is corrected by the equalizer 4, and this carrier is converted to N
The data is transmitted to the telephone network 2 through the CU 3. As a result, the called-side facsimile apparatus receives a carrier having a completely flat frequency characteristic in which the distortion caused by the telephone line network 2 and the receiving characteristic of the called-side facsimile apparatus are cancelled. By demodulation, the image data PIX can be accurately reproduced.

As described above, in the present embodiment, the test signal is transmitted from the calling side to the called side, the frequency characteristic of the test signal is measured by the called side, and the calling side is measured based on the measurement result. The frequency characteristics of the equalizer 4 are corrected. This makes it possible to transmit and receive image data with the effects of the telephone network 2 and the called facsimile machine being offset. Therefore, unlike the related art, there is no need to set and register the correction characteristics of the equalizer for each destination.

The present invention is not limited to the above embodiment, but can be variously modified. For example, as shown in FIG. 8, the training check signal TCF may be used as a test signal, and the reception preparation confirmation signal CFR may include data indicating the frequency characteristics of the test signal. This can avoid complication of the facsimile communication procedure between the calling side and the called side. The frequency characteristic of the training check signal TCF is substantially flat in a frequency band of 150 Hz to 3750 Hz, for example, as shown in FIG. The frequency characteristic of the training check signal TCF received by the called facsimile machine changes as shown in FIG. 10, for example, due to the influence of the telephone line network and the called facsimile machine. The frequency characteristic is measured on the called side, and the frequency characteristic of the equalizer 4 on the calling side is corrected based on the measurement result. Conventionally, the called side only determines whether or not the training check signal TCF has been received, so that the training check signal TCF is used more effectively.

Although the test signal is exemplified by signals of five kinds of frequencies, three kinds of signals of low frequency, middle frequency and high frequency may be used. In this case, the measurement time can be shortened without substantially lowering the measurement accuracy. Further, a signal having two kinds of frequencies or a signal having six or more kinds of frequencies can be adopted as the test signal.

Further, the facsimile apparatus on the image transmitting side only needs to include at least the frequency setting unit 17, and the facsimile apparatus on the image receiving side only needs to include at least the frequency measuring unit 16.

The present invention can be applied to any type of terminal as long as it functions as a facsimile machine.

[0058]

As described above, according to the present invention, a test signal is transmitted from a transmitting facsimile apparatus to a receiving facsimile apparatus, and the frequency characteristics of the test signal are measured by the receiving facsimile apparatus. The test signal is distorted when transmitted through the telephone network between the respective facsimile apparatuses, and its frequency characteristic changes depending on the reception characteristic of the receiving facsimile apparatus. Therefore, based on the measurement result of the frequency characteristics of the transmitted test signal, the characteristics of the equalizer of the transmission-side facsimile apparatus are set, and the transmission signal is corrected by the equalizer, thereby distorting the telephone line network and the reception-side facsimile apparatus. Cancels the receiving characteristics of Therefore, unlike the conventional apparatus, there is no need to grasp and manage the data of the destination.

Further, according to the present invention, the test signal includes at least low frequency, middle frequency and high frequency signals. If the frequency characteristics are measured based on these three types of signals, it is possible to maintain good measurement accuracy and correction accuracy while shortening the measurement time.

Further, according to the present invention, the test signal is 4
It contains signals of more than one kind of frequency. As the number of types of signals is increased, the measurement accuracy and the correction accuracy are improved.

Further, according to the present invention, the test signal is included in the non-standard function setting signal transmitted / received from the transmission-side facsimile apparatus to the reception-side facsimile apparatus.
It is included in the non-standard function signal transmitted and received from the receiving facsimile machine to the transmitting facsimile machine. In the existing facsimile machine, the test signal and the measurement result can be transmitted and received using the non-standard function setting signal and the non-standard function signal.

Further, according to the present invention, the test signal is used together with the training signal transmitted and received from the transmitting facsimile apparatus to the receiving facsimile apparatus. In an existing facsimile machine, a training signal can be used as a test signal.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a communication procedure by the facsimile apparatus of the embodiment.

FIG. 3 is a flowchart showing a control procedure for switching a setting level of an equalizer by the facsimile apparatus of the embodiment.

FIG. 4 is a graph showing frequency characteristics of a test signal in the facsimile apparatus of the present embodiment.

FIG. 5 is a graph showing frequency characteristics of a test signal transmitted through a telephone network and received by a called facsimile machine.

FIG. 6 is a diagram showing an equalizer setting management table in the facsimile apparatus of the embodiment.

FIG. 7 is a graph showing a frequency characteristic of an equalizer by the facsimile apparatus of the embodiment.

FIG. 8 is a diagram showing a modification of the communication procedure by the facsimile apparatus of the embodiment.

FIG. 9 is a graph illustrating a frequency characteristic of a training check signal;

FIG. 10 is a graph showing a frequency characteristic of a training check signal transmitted through the telephone network and received by the called facsimile machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Facsimile apparatus 2 Telephone network 3 Network control unit (NCU) 4 Equalizer 5 Equalizer switching control unit 6 Modem 7 Image memory 8 ROM 9 RAM 10 Display unit 11 Operation unit 12 Document reading unit 13 Printing unit 14 Encoding / decoding unit 15 Control unit 16 Frequency measurement unit 17 Frequency setting unit 18 Test signal generation unit 21 Equalizer setting management table

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiro Tanaka 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside (72) Inventor Kotoshi Okubo 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Incorporated (72) Inventor Atsushi Tanaka 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Inside (72) Inventor Jin Yamamoto 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka F Term (reference) 5C075 CA01 CB05 CB09 5K046 AA01 BB04 EE12 EE42 EF05

Claims (7)

[Claims] 1. A test signal communication means for communicating a predetermined test signal from a transmitting facsimile apparatus for transmitting an image to a receiving facsimile apparatus for receiving an image, and receiving the test signal, Frequency characteristic measuring means for measuring the frequency characteristic and transmitting the measurement result to the transmission-side facsimile apparatus; and receiving the measurement result, an equalizer setting for setting the characteristic of an equalizer for correcting the transmission signal in accordance with the measurement result. And a facsimile apparatus. 2. The facsimile apparatus according to claim 1, wherein the test signal includes at least low-frequency, middle-frequency, and high-frequency signals. 3. The facsimile apparatus according to claim 1, wherein the test signal includes signals of four or more types of frequencies. 4. The test signal is included in a non-standard function setting signal transmitted / received from the transmitting facsimile apparatus to the receiving facsimile apparatus, and a measurement result is transmitted / received from the receiving facsimile apparatus to the transmitting facsimile apparatus. 4. The facsimile apparatus according to claim 1, wherein the facsimile apparatus is included in a non-standard function signal. 5. The facsimile apparatus according to claim 1, wherein the test signal is used together with a training signal transmitted / received from the transmitting facsimile apparatus to the receiving facsimile apparatus. 6. A test signal transmitting means for transmitting a preset test signal to a partner terminal, and an equalizer for correcting a transmission signal when receiving a measurement result indicating a frequency characteristic of the test signal from the partner terminal. A facsimile apparatus comprising: an equalizer setting unit for setting a value according to the measurement result. 7. A facsimile apparatus comprising a frequency characteristic measuring means for measuring a frequency characteristic of a test signal when receiving a test signal from a partner terminal and transmitting the measurement result to the partner terminal.