JPH08265452A - Dtmf signal detecting device and facsimile equipment - Google Patents

Abstract

PURPOSE: To make it possible to set up a DTMF detection on/off time matched with a user's use environment without compelling the user to depress a remote switch for a long time and to surely prevent the generation of DTMF misdetection. CONSTITUTION: Only DTMF detection off time is extended without changing a DTMF detection on time. When a busy DTMF component is learnt, only the DTMF detection off time or both the DTMF detection off time and DTMF detection on time is extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DTMF signal detecting apparatus and a facsimile apparatus capable of preventing erroneous detection of a DTMF signal.

[0002]

2. Description of the Related Art Conventionally, when a telephone set and a facsimile apparatus are connected to one subscriber telephone line by a branch circuit, the telephone set is usually connected to the telephone set, but the user of the telephone set can switch the switching device. To connect to a facsimile machine. Further, when the telephone and the facsimile are arranged at remote locations, the user presses the prescribed dial number of the telephone once or twice to switch and connect to the facsimile. There is a switching function. On the other hand, when calling the facsimile machine from the other side, the DTMF of the specified frequency is used.
By transmitting the (Dial Tone Multi Frequency) signal for a certain length or longer, the switching device is operated to switch from the telephone to the facsimile device, and the facsimile device is activated. For example, JP-A-1-202094
In the "DTMF signal detection device" described in the publication, the erroneous detection rate of voice is determined by determining that the DTMF signal is valid and outputting it only when the signal length of the received DTMF signal is longer than the valid signal length. It is decreasing. In the above detection device, the effective signal length is stored in the storage device in advance, and the detected D
The TMF signal and the effective signal length read from the storage device are compared by the comparison circuit, and only the DTMF signal longer than the effective signal length is determined to be effective. In addition, JP-A-63-268
In the "voice signal storage device" described in Japanese Patent No. 352 publication, when a voice signal input from a telephone line is stored and then reproduced, the DTMF signal detection circuit detects the DTMF signal during the period. Does not store the input signal. This prevents the facsimile apparatus from being accidentally switched by the DTMF signal generated during reproduction.

[0003]

In a normal DTMF detection circuit, when a characteristic curve in which the horizontal axis represents the frequency and the vertical axis represents the detection frequency, a DTMF in a certain frequency range (± 10 Hz) is drawn.
A signal can be detected 100%, and the detection frequency decreases as the frequency increases. Therefore, in the case of the DTMF detection circuit having a relatively wide detection frequency range, the DTMF signal is erroneously detected by a voice or music other than the DTMF signal from the telephone, and the remote switching function of the facsimile operates. Then, there is a problem that the mode is arbitrarily switched to the facsimile mode. In such a case, the detection frequency range of the detection circuit may be changed to narrow the detection width as much as possible, but there is a risk of making it too narrow, and a normal DTMF may be used.
There is also concern about malfunctions, such as not being able to detect signals.
Therefore, in consideration of safety, in many cases, the detection frequency width is slightly widened in order to prevent cost increase. An object of the present invention is to solve such a conventional problem and turn on DTMF detection suitable for a user's usage environment.
Time and DTMF detection OFF time can be set,
An object of the present invention is to provide a DTMF signal detection device and a facsimile device that can reliably prevent erroneous detection of a DTMF signal and that does not require the user to extend the time for pressing the remote switching button.

[0004]

In order to achieve the above object, the DTMF signal detecting apparatus of the present invention detects a DTMF signal from a facsimile apparatus and a telephone connected to the same line. In the DTMF signal detection device that is switched and connected to the facsimile device,
A DTMF detection circuit capable of arbitrarily setting an F detection ON time and a DTMF detection OFF time, and a DT of the DTMF detection circuit
The MF detection ON time remains equivalent to the DTMF transmission time, and
A control means for extending only the TMF detection OFF time is provided. Further, a DTMF detection circuit that can arbitrarily set the DTMF detection ON time and the DTMF detection OFF time, and a DTMF detection circuit that learns the DTMF component input during a call and erroneously detects the DTMF component as a DTMF signal. DTM
It is also characterized by including a control means for extending only the F detection OFF time. Further, a DTMF detection circuit that can arbitrarily set the DTMF detection ON time and the DTMF detection OFF time, and a DTMF detection circuit that learns the DTMF component input during a call and erroneously detects the DTMF component as a DTMF signal. DTM
It is also characterized by including a control means for extending the F detection ON time and the DTMF detection OFF time. Furthermore, the facsimile apparatus of the present invention is capable of arbitrarily setting the DTMF detection ON time and the DTMF detection OFF time.
Detection circuit and DTMF detection OFF of the DTMF detection circuit
Time only or DTMF detection ON time and DTMF
And a control means for extending both of the detection OFF times.

[0005]

In the present invention, the DTMF component input during a call is automatically learned, and if a DTMF error is detected, the DTMF detection OFF time is automatically extended or the DTMF detection OFF time is increased.
By extending both the MF detection ON time and the DTMF detection OFF time, erroneous detection is reliably prevented. In the DTMF signal detection circuit having a wide detection frequency range, the DTM signal is detected by a voice or music other than the DTMF signal input from the telephone.
Although the F signal may be erroneously detected, in the present invention, the DTMF detection ON time and the DT are automatically detected as described above.
Since the MF detection OFF time is extended, there is no need for the user to press the remote switch for a long time, and the DTM
False detection of F can be prevented. Then, the DTMF detection ON time and the DTMF detection O that match the usage environment of the user are automatically counted by automatically counting the situation of erroneous detection of DTMF.
The FF time can be set.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of a facsimile apparatus to which the present invention is applied. In FIG. 1, 11 is a CPU for controlling the entire facsimile apparatus, 12 is a communication modem,
Reference numeral 13 is a network control unit (NCU), 14 is a plotter for printing a received message, 15 is a scanner for reading a document, 16 is a DTMF detection circuit for detecting a DTMF signal, and 17 is a program executed by the CPU 11. ROM for storing, 18 is a system RAM for storing various setting data of the system, 19 is a memory RAM for storing operating data, 20 is a decoder (DCR) for compressing and expanding image information, Reference numeral 21 is an operation unit equipped with push buttons, a panel and the like, and 22 is a bus. By the way, as described above, as an application of the facsimile apparatus which detects the DTMF signal, there is a remote switching function. This remote switching function is
It is pushed twice to prevent erroneous detection. For example, after making a call between telephones attached to a facsimile machine, a facsimile is transmitted, and both users press a specific dial number (for example, 2) of the telephone as a remote switching function. DTM
The F signal is transmitted and input to both facsimile machines, and the facsimile machines are switched and connected to each other via a telephone line. If you press twice, you will press No. 2 twice, so
The DTMF signal is also transmitted twice.

FIG. 2 is a timing chart of the DTMF signal and the detection signal. As shown in FIG. 2, the DTMF signal becomes an OFF time after having become an ON time for a certain time. In the case of pressing twice, this is repeated twice. Then, the DTMF detection circuit can detect the DTMF detection ON time for a specified length (usually 70 ms) (OK),
Next, the DTMF detection OFF time is a specified length (usually 10
Only when 0 ms to 200 ms) is detected (OK), it is determined that the DTMF is detected, and the telephone device can be switched to the facsimile device. When pressing twice, the ON detection time and OFF detection time of the specified length are repeated.
When the number of times is confirmed, it is determined that DTMF has been detected. However, even if it is pressed twice, as described above, when the music or the voice is input to the handset, the DTMF detection circuit having a wide detection frequency width has a DT longer than the specified time.
By detecting the MF detection ON time and the DTMF detection OFF time, there is a possibility that erroneous detection may occur.

[0008] Also, a one-shot type telephone device which sends only a DTMF signal for a prescribed time, whether it is pushed for a long time or momentarily, cannot be dealt with by a method of lengthening the DTMF detection ON time. Further, adopting a method of lengthening the pressing time of the user requires a pressing time, which is not preferable for the user. Therefore, in the present invention, the DTMF detection ON time is D
By extending only the DTMF detection OFF time while keeping the TMF sending time equivalent, the probability of erroneously detecting pulse-wise DTMF is reduced. That is, the interval at which the user presses twice is considerably longer than the ON time of the DTMF. In addition, the DT that repeatedly transmits from the facsimile device
The OFF time of the MF signal is considerably longer than the ON time. Therefore, in the present invention, even if the DTMF detection OFF time is extended, there is still a margin in the OFF time. In FIG. 2, the case where the DTMF signal is transmitted from the other party three times and the DTMF signal twice when pressed twice (in this case, excluding the first ON time of FIG. 2) are shown. And That is, in the case of music or voice, it is ON
There is almost no case where the stationary time continues for more than 200 ms after the time, the ON time is immediately reached, and noise is often generated, so erroneous detection can be reliably prevented.

FIG. 3 is a busy D showing an embodiment of the present invention.
It is an operation | movement flowchart of the signal detection apparatus which learns a TMF component. First, the phone is off hook. It is judged whether or not the call is off-hook by the incoming call history, that is, the incoming call from another person (step 101), and the operation is stopped unless the incoming call is received (step 108). This is when you go off-hook trying to make a call
This is because a specific dial number (for example, number 2) is pressed and the remote switching function is activated, so that it is avoided. That is, in this operation flow, it is only to test whether or not a malfunction occurs due to DTMF components such as music and voice input during a call. On the other hand, if there is an incoming call history, remote switch detection is started (step 1
02). During the call, the DTMF component is input from the other party's telephone or your own telephone due to noise, speech, music, etc., so that the first remote switching number (for example, number 2)
Is detected (that is, if the first erroneous detection is made) (step 103), the double-press timer is set (step 104). The double press timer time is set to about 800 ms. As is clear from FIG. 2, the DTMF time by double pressing is 540 ms, which is the time obtained by adding the detection ON time of 70 ms and the detection OFF time of 100 to 200 ms twice, and thus is sufficiently set within 800 ms. If the second press timer is not exceeded, the second and subsequent DTMFs are also erroneously detected. The second remote switching number is erroneously detected (step 106), and the mode is switched to the facsimile mode (step 107). When the second remote switching number is not erroneously detected (step 106), the step 105 is performed again.
Returning to step 2, it is determined whether or not the timer is pressed twice and the timer has expired.

On the other hand, when the double-press timer expires (step 105), it is determined that the second DTMF signal has not been erroneously detected. Remote switching is 2
Since the button is pressed once, if the first time is detected and the second time cannot be detected, it is also judged as an erroneous detection.
When a false detection is made, both the false detection counter and the false detection DTMF type are set (step 109). In other words, as the information that was erroneously detected, the remote switching number and
A value obtained by incrementing the content of the counter corresponding to the number by 1 is stored in the corresponding area of the system RAM 18 shown in FIG. In this case, the DTMF numbers 0-9
An erroneous detection counter is prepared for each, and the content of the counter is incremented by 1 for each erroneous detection. These counters may be hardware, but may be programs having a counter function. If the erroneous detection counter of any DTMF number reaches the threshold (A) (step 110), the DTM
The F detection OFF time is extended (step 111). That is, the DTMF detection ON time of the DTMF signal shown in FIG. 2 is kept as it is, and only the DTMF detection OFF time is automatically extended. In this processing, the DTMF detection OFF time in the DTMF detection circuit 16 in FIG. 1 may be made expandable and contractible and automatically adjusted by a program.

FIG. 4 is an operation flowchart showing a modified embodiment of FIG. In the case of FIG. 3, when the value of the false detection counter reaches the threshold (A), only the set time of the DTMF detection OFF time is extended. On the other hand, in the case of FIG. 4, if the number larger than the threshold (A) is the same as the remote switching number (here, number 2), the DTMF detection OFF time and DTM are detected.
F detection ON time is also extended. That is, the remote switching numbers are sequentially assigned to the numbers 0 to 9 and the remote switching function is activated each time, but when the double-press timer expires, the counters for the numbers 0 to 9 are incremented by 1 and the numbers 0 to 9 are added. The number is identified and set. FIG.
Then, when the double-press timer expires (step 105 in FIG. 3), the types of the false detection counter and the false detection DTMF are set (step 109). Then, if the value of the false detection counter becomes larger than the threshold (A) (step 110), it is further determined whether or not the number is the same as the remote switching number (step 112). The detection OFF time is extended and the DTMF detection ON time is extended (step 11).
3). Then, the process returns to step 103. If it is not the same as the remote switching number, only the DTMF detection OFF time is extended (step 111). This enables DTMF detection O
FF time from 100 to 200 ms sequentially from 250 to 300
It is extended to more than ms and the DTMF detection ON time is 70
Since it extends from 80 ms to 80 ms or more, at the end,
The second press timer does not expire and the first remote switching number is no longer detected.

[0012]

As described above, according to the present invention,
Since the DTMF detection OFF time is lengthened, it is possible to reliably prevent DTMF erroneous detection without forcing the user to lengthen the pressing time by remote switching.
Further, since the situation of erroneous detection of DTMF is automatically counted, it is possible to set the DTMF detection ON time and the DTMF detection ON time that match the user's usage environment, thereby preventing DTMF erroneous detection. .

[Brief description of drawings]

FIG. 1 is a block diagram of a facsimile apparatus to which the present invention is applied.

FIG. 2 is a time chart of a DTMF signal and a detection signal in the present invention.

FIG. 3 is an operation flowchart of the DTMF signal detection device of the present invention.

FIG. 4 is an operation flowchart showing a modified example of FIG.

[Explanation of symbols]

11 ... CPU, 12 ... Modem, 13 ... NCU, 14 ... Plotter, 15 ... Scanner, 16 ... DTMF detection circuit, 1
7 ... ROM, 18 ... System RAM, 19 ... Memory RAM, 20 ... DCR, 21 ... Operation part, 22 ... Bus.

Claims (4)

[Claims] 1. A DTMF detection ON time and a DTMF detection OFF in a DTMF signal detection apparatus for switching and connecting a facsimile machine and a telephone connected to the same line by detecting a DTMF signal to switch the facsimile machine to the facsimile. A DTMF detection circuit whose time can be arbitrarily set, and the DTMF detection ON time of the DTMF detection circuit is DTMF
And a control means for extending only the DTMF detection OFF time while maintaining the transmission time.
MF signal detector. 2. A DTMF signal detection device for switching and connecting a facsimile device and a telephone set connected to the same line to a facsimile device by detecting the DTMF signal, the DTMF detection ON time and the DTMF detection OFF state. A DTMF detection circuit that can set the time arbitrarily and learns the DTMF component input during a call,
Each time a component is erroneously detected as a DTMF signal, the DTMF signal is detected.
A DTMF signal detection device comprising: a control means for extending only the DTMF detection OFF time of the detection circuit. 3. A DTMF detection ON time and a DTMF detection OFF in a DTMF signal detection device for switching and connecting a facsimile device and a telephone set connected to the same line by detecting the DTMF signal from the telephone set to the facsimile device. A DTMF detection circuit that can set the time arbitrarily and learns the DTMF component input during a call,
Each time a component is erroneously detected as a DTMF signal, the DTMF signal is detected.
Detection circuit DTMF detection ON time and DTMF detection OFF
A DTMF signal detection device comprising: a control means for extending the time. 4. DTMF detection ON time and DTMF detection OF
A facsimile equipped with a DTMF detection circuit capable of arbitrarily setting the F time and a control means for extending only the DTMF detection OFF time of the DTMF detection circuit or extending both the DTMF detection ON time and the DTMF detection OFF time. apparatus.