JPS6340936Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a facsimile transmission mode identification system that automatically identifies the other party's transmission mode on the receiver side based on the phase signal sent from the transmitter in order to perform phase matching before transmitting the image signal. It is related to the device.

Generally, in facsimile communication, a phase signal is sent from a transmitter to a receiver in order to perform phase matching before transmitting an image signal. At this time, if the other party's transmission mode is only one, or if you know which transmission mode it is in advance,
By creating a signal with the same period as the phase signal sent on the receiver side and establishing start-stop synchronization between the two, phase matching can be easily performed.

However, in recent years, due to factors such as the number of white pixels and black pixels, the type of original to be sent, and different transmission times, differences in white feed and black feed, differences in scanning cycles, etc.
Various transmission modes are used, including different carrier frequencies. Such transmission modes may differ depending on the type of transmitter, or one transmitter may be provided with a changeover switch and have multiple transmission mode functions by manually switching this switch. When there are multiple transmission modes as described above, the receiver side must know the other party's transmission mode, that is, whether it is white feed or black feed, and the scanning period before phase matching.

Therefore, it is necessary for facsimile receivers to identify the transmission mode of the other party before phase matching and to switch the circuit according to this transmission mode. Conventionally, the following means have generally been used.

In other words, the receiver is equipped with a changeover switch, and the receiver operator manually performs the changeover after prior consultation, or the transmitter sends out a control signal of a specific frequency corresponding to the transmission mode and the receiver receives the control signal. Means for receiving and detecting this control signal and automatically switching to a circuit for the other party's signal mode is in practical use.

However, the former method, in which the operator of the receiver manually performs the switching, has the disadvantage that automatic reception is not possible and manual operation is always required, making it easy for operational errors to occur. In addition, with the latter method of automatically switching to the circuit for the other party's signal mode, if the line being used is a narrow band such as a subscriber telephone line, the control signal will be close to the receiver. The disadvantage of this method is that it requires a highly selective filter and requires the use of a fairly expensive filter. Furthermore, if the communication audio due to noise mixed into the line or incorrect connection contains the same frequency component as the control signal, it will naturally cause a malfunction, and it will take an extremely long time to send out the image signal due to re-identification. In short, this led to a rise in communication charges and was not suitable for facsimile communications, which have been competing for seconds in recent years.

In view of the above points, the present invention was devised to solve such problems and eliminate such drawbacks. An object of the present invention is to provide an inexpensive facsimile transmission mode identification device that accurately and automatically identifies a transmission mode, has significantly improved discrimination accuracy without malfunctioning due to noise, and is inexpensive.

In order to achieve such an objective, the present invention includes a linear detection circuit that extracts an envelope signal of an input signal,
A counter that performs a timing operation while the envelope signal from this linear detection circuit is supplied as an enable signal and sequentially sends out output signals after a predetermined period of time has elapsed.
a timer circuit, a plurality of detection units that monitor whether or not the continuous time of the upper front envelope signal is within each specified time width determined by the output from the counter/timer circuit; and each of these detection units. The transmitter is provided with a plurality of mode discriminating counters that each count output pulses of the sections and output a transmission mode identification signal when the count value reaches a certain number.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing an embodiment of a facsimile transmission mode identification device according to the present invention.

Roughly divided in Fig. 1, there is a linear detection circuit 1 which takes a phase signal as an input and extracts this input signal as an envelope signal, and a linear detection circuit 1 which takes a phase signal as an input and extracts this input signal as an envelope signal, and a linear detection circuit 1 which takes the above-mentioned envelope signal period as a counting period and uses a timing pulse CP as a counting input and after a specified time elapses. a counter/timer circuit 2 that sequentially sends out output signals, that is, performs a timing operation while the envelope signal from the linear detection circuit 1 is supplied as an enable signal, and sequentially sends out output signals after a predetermined period of time; The line signal is input, and the output signal of the counter/timer circuit 2 is input as a strobe pulse. A plurality of detection units 3A to 3D monitor whether or not the envelope signal is within each predetermined time width determined by the envelope signal, and are reset when the envelope signal ends, and each of these detection units 3A
~A plurality of mode discrimination counters 4A that count each 3D output pulse and output a transmission mode identification signal when the count value reaches a certain number~
It is composed of 4D.

The detection units 3A to 3D are set to the first memory circuits 5A to 5D if the envelope width is equal to or greater than the minimum time for making the prescribed time width, and are reset if the envelope width is less than the maximum time and if it is longer than that. The second memory circuits 6A to 6D to be set, and the first and second memory circuits 5A, 5B, 5
The state of C, 5D and 6A, 6B, 6C, 6D is 5A
= “H”, 6A = “L”, the envelope signal width is within the specified time width of the detection unit, and the selection confirmation output pulse circuit sends out an output pulse indicating that one transmission mode has been confirmed. 7A to 7D. The detection units 3A to 3D correspond to the detection units for the input signals A to D shown in FIG. 2, respectively. Further, timing pulses for controlling the storage circuits of these detection units 3A to 3D are sent from the counter/timer circuit 2 to the respective storage circuits 5A to 3D.
5D, 6A to 6D.

Next, the operation of the embodiment shown in FIG. 1 will be explained with reference to the operation diagrams shown in FIGS. 2 to 7. FIG. 2 is a waveform diagram of a phase signal consisting of an intermittent frequency signal sent from a transmitter before sending out an image signal, and the shaded area shows the part where the frequency signal exists. Figure 2A is a waveform diagram where the phase signal is sent in black feed, and the part where the frequency signal is present becomes the phase signal, and Figures 2B to D are waveform diagrams where the phase signal is sent in white feed, where the frequency signal is The blanking portion that does not exist becomes a phase signal. The phase signals shown in FIGS. 2A to 2D have different combinations of white feed and black feed and scanning period, indicating that the transmission modes are different. Note that the phase signal width is generally 5± of one scanning period.
However, in FIG. 2, these phase signal widths are set to a constant width for convenience of explanation.

First, the detection units 3A to 3A, which perform common operations,
In 3D, the means for confirming the selection of the envelope signal width will be explained. FIG. 3 shows the first and second storage circuits 5A to 5D, 6A to 6 provided inside the detection units 3A to 3D due to changes in the signal width T of the envelope signal S.
7 is a time chart showing the operation of D and selection confirmation output pulse circuits 7A to 7D. Note that T _MIN indicates the minimum time to create a prescribed time width corresponding to a certain transmission mode, and T _MAX indicates the maximum time.

FIG. 3a shows the signal width T of the envelope signal S.
is a time chart showing the operation in the case of T<T _MIN , and since the envelope signal S turns off before the timing pulse of the counter/timer is output, the first memory circuits 5A to 5D are not set. No output is sent from the selection confirmation output pulse circuits 7A to 7D.

Figure 3b shows that the signal width T of the envelope signal S is T _MIN
This is a time chart showing the operation in the case of <T _MAX , and the signal width T of the envelope signal S is T _MIN <T
Therefore, the first memory circuits 5A to 5D are set by the timing pulse. However, T _MAX
Since the envelope signal S is turned off before the timing pulse corresponding to is output from the counter/timer circuit 2, the second memory circuits 6A to 6D are not set. Therefore, the first memory circuits 5A to 5D
The output of the second memory circuits 6A to 6D is "H", and the outputs of the second memory circuits 6A to 6D are "L". Based on this condition, the selection confirmation output pulse circuits 7A to 7D are triggered by the falling edge of the envelope signal S and output pulses. Send out. That is, this selection confirmation output pulse has a signal width T of the envelope signal S.
This indicates that the value was within the specified range.

FIG. 3c shows that the signal width T of the envelope signal S is
This is a time chart showing the operation when T _MAX <T, and the signal width T of the envelope signal S is T _MAX <
Since it is T, the first memory circuits 5A to 5D are set, and further the second memory circuits 6A to 6D are set. Therefore, selection confirmation output pulse circuit 7A
-7D, no output pulse is sent out even if it is triggered by the falling edge of the envelope signal S.

In this manner, the selection of the envelope signal S is confirmed in each of the detection units 3A to 3D.
Then, a signal specifying the minimum time T _aMIN -T _dMIN of each specified time width for monitoring the envelope signal width T _a -T _d of the input signal shown in FIGS. 2A to D, and a maximum time T _aMAX - The signal specifying T _dMAX is a counter
It is output from timer circuit 2.

The respective operations when the phase signals A to D shown in FIG. 2 are input will be described below.

When the phase signal A is input When the phase signal shown in Fig. 2A is supplied to the input terminal _Io shown in Fig. 1, the output of the linear detection circuit 1 is as shown in Fig. 2B. The waveform will be as shown in FIG. 4a, which is a time chart showing the operation of each part in FIG. Then, this envelope signal is used as the count signal of the counter/timer circuit 2.
By being supplied to the enable terminal ENB,
The counter/timer circuit 2 starts counting the timing pulse CP supplied to the clock terminal CK.

When the time measured by the counter/timer circuit 2 reaches T _MIN , the minimum time signal of the specified time width corresponding to the transmission mode A is output from the output terminal 1.
T _aMIN is sent. (See Figure 4b). As a result, the first memory circuit 5A is set as shown in FIG. 4c. However, since the envelope signal width T _a in this case is T _{a MIN} < T _a < T _{a MAX} , the T _{a MAX} signal is not sent out from the output terminal 2 of the counter/timer circuit 2 (dashed line in FIG. 4 d). The second memory circuit 6A is not set. (See Figure 4e). Therefore, it can be seen that this envelope signal width T _a is a signal within the specified time width. Then, when the conditions for the "H" output of the first memory circuit 5A and the "L" output of the second memory circuit 6A are satisfied, the selection confirmation output pulse circuit 7A is triggered at the falling edge of the envelope signal. be done. As a result, a pulse as shown in FIG. 4f is sent from the selection confirmation output pulse circuit 7A to the mode discrimination counter 4A. At the same time, the first memory circuit 5A is reset by the fall of the envelope signal, and the counter/timer circuit 2 is also reset to return to the initial state.
Similar operations are then repeated with the next envelope signal. As a result, the mode discrimination counter 4A, which counts the output pulses of the detection section 3A,
When the output pulses from the detection section 3A reach a certain number as shown in FIG. 4f, the mode discrimination output is sent to the output terminal.
It will now be sent to _OutA . (See Figure 4g) At this time, since the signal width of the frequency signal portion of the phase signal A is T _a < T _b < T _c < T _d , the counter
No pulses are sent out from the output terminals 3 to 8 of the timer circuit 2. Therefore, when input signal A is input, no output appears in the other mode detection sections.

When a phase signal B is input When a phase signal as shown in Fig. 2B is supplied to the input terminal _Io , the output of the linear detection circuit 1 is the same as when the signal shown in Fig. 2B is input. The waveform is as shown in FIG. 5a, which is a time chart showing the operation of each part in the figure. Then, by supplying this envelope signal to the count enable terminal ENB of the counter/timer circuit 2, the counter
The timer circuit 2 starts counting the clock pulse CP.

When the time measured by the counter/timer circuit 2 reaches T _MIN , the minimum time signal of the specified time width corresponding to the transmission mode B is output from the output terminal 3.
T _bMIN is sent. (See Figure 5b). As a result, the first memory circuit 5B is set as shown in FIG. 5c. However, since the envelope signal width T _b in this case is T _{b MIN} < T _b < T _{b MAX} , the T _{b MAX} signal is not sent out from the output terminal 4 of the counter/timer circuit 2 (dashed line in FIG. 5 d). The second memory circuit 6B is not set. (See Figure 5e). Therefore, it can be seen that this envelope signal width T _b is a signal within the specified time width. Then, when the conditions for the "H" output of the first memory circuit 5B and the "L" output of the second memory circuit 6B are satisfied, the selection confirmation output pulse circuit 7B is triggered at the falling edge of the envelope signal. be done. As a result, a pulse as shown in FIG. 5f is sent from the selection confirmation output pulse circuit 7B to the mode discrimination counter 4B. At the same time, the first memory circuit 5B is reset by the fall of the envelope signal, and the counter/timer circuit 2 is also reset to return to the initial state. Similar operations are then repeated with the next envelope signal. As a result, the mode discrimination counter 4B that counts the output pulses of the detection section 3B
When the number of output pulses from the detection section 3B reaches a certain number as shown in FIG. 5f, a mode discrimination output is sent to the output terminal _OutB . At this time, the signal width of the frequency signal portion of signal B is T _a < T _b < T _c
Since <T _d , no pulses are sent from the output terminals 5 to 8 of the counter/timer circuit. However, as shown in Figure 5g and j, the T _aMIN signal and T _aMAX signal
The signal is sent from the counter/timer circuit and sets the first and second storage circuits of the detection section 3A, respectively. (See Figure 5 h, k). However, the first
The memory circuit 5A outputs "H", and the second memory circuit 6
Since A is an "H" output, the selection confirmation output pulse circuit does not send out a pulse even if it is triggered by the falling edge of the envelope signal. Therefore, only the selection confirmation output pulse circuit 3B outputs a pulse.

When a phase signal C is input When a phase signal as shown in FIG. 2C is supplied to the input terminal _Io , the output of the linear detection circuit 1 is The waveform is as shown in FIG. 6a, which is a time chart showing the operation of each part in the figure. Then, by supplying this envelope signal to the count enable terminal ENB of the counter/timer circuit 2, the counter
The timer circuit 2 starts counting the clock pulse CP.
When the time measured by the counter/timer circuit 2 reaches T _MIN , the minimum time signal T _cMIN of the specified time width corresponding to the transmission mode C is output from the output terminal 5.
is sent. (See Figure 6b). As a result, the first memory circuit 5C is set as shown in FIG. 6c. However, in this case, the envelope signal width
Since _Tc satisfies _TcMIN < _Tc < _TcMAX , the _TcMAX signal is not sent out from the output terminal 6 of the counter/timer circuit 2 (dashed line in FIG. 6d), and the second memory circuit 6C is not set. (See Figure 6e). Therefore,
It can be seen that the envelope signal width T _c is a signal within a specified time width. Then, when the conditions for the "H" output of the first memory circuit 5C and the "L" output of the second memory circuit 6C are satisfied, the selection confirmation output pulse circuit 7C is triggered at the falling edge of the envelope signal. be done.

By this, selection confirmation output pulse circuit 7
A pulse as shown in FIG. 6f is sent from C to the mode discrimination counter. At the same time, the first memory circuit 5C is reset by the fall of the envelope signal, and the counter/timer circuit 2 is also reset to return to the initial state. Similar operations are then repeated with the next envelope signal. As a result, the mode discrimination counter 4C that counts the output pulses of the detection section 3C outputs the mode discrimination output to the output terminal O _utC when the number of output pulses from the detection section 3C reaches a certain number as shown in FIG. It will start sending out. At this time, since the signal width of the frequency signal portion of the signal C satisfies Ta < _{T b} < T _c < T _d , no pulses are sent out from the output terminals 7 to 8 of the counter/timer circuit 2 . However, from the output terminals 1 to 4 of the counter/timer circuit 2, T _aMIN and
Signals T _aMAX , T _bMIN , and T _bMAX are sent out to set the first and second storage circuits of the detection section 3A and the detection section 3B. However, since the first memory circuit outputs "H" and the second memory circuit outputs "H", the selection confirmation output pulse circuits 7A and 7B do not output pulses even when triggered by the fall of the envelope signal. Not sent. Therefore, the selection confirmation output pulse circuit 7
Only C outputs a pulse. The operations of the detection sections 3A and 3B are the same as when the B signal is input, so they are omitted from the time chart shown in FIG.

When phase signal D is input When a phase signal as shown in Figure 2 D is supplied to input terminal _Io , it is output only from mode discrimination counter 4D in the same way as when signals B and C are input as described above. Output appears at the end (O _utD ). Since the operation in this case is clear from the above, the details will be omitted.

As explained above in detail, the facsimile transmission mode identification circuit according to the present embodiment uses a linear detection circuit to extract the intermittent frequency signal constituting the phase signal as an envelope signal, The time is monitored by a counter/timer and a detection unit, and a pulse is output only when the continuous signal width is within a specified time width, and when the number of pulses reaches a certain number, a transmission mode identification output is sent out. This is how it was done. With this configuration, the transmission mode can be reliably identified without using a high-performance filter that is conventionally required to extract only frequency signals. Furthermore, in the conventional method, it was necessary to add another discrimination method to distinguish between transmission modes in which the frequency signal is the same but the phase signal period is different, but with this embodiment, it is possible to identify transmission modes reliably by one identification can be identified. In addition, the phase signal period is the same as shown in Figure 7, which is an input signal waveform diagram for white feed mode and black feed mode, and the transmission mode is black feed (see Figure 7 a) and white feed (see Figure 7a). 7b)), such transmission modes can also be identified according to this embodiment.

Note that the phase signal width is generally 5±1% of one scanning period of the screen, so if this signal width can be tolerated, the output terminals 2 and 3, 4 and 5 of the counter/timer 2,
6 and 7 can be used in common, and in this case, the storage circuits can also be used in common.

Furthermore, it goes without saying that the intermittent frequency signal constituting the phase signal may also be used as the carrier frequency of the image signal.

As explained above, according to the present invention, the intermittent frequency signal constituting the phase signal is extracted as an envelope signal, a time measurement operation is performed while this envelope signal is supplied as an enable signal, and the envelope signal is Since the transmission mode is identified by detecting whether or not the continuous time of This has the advantage that the discrimination accuracy is greatly improved, and even if the transmission modes have different frequency signals or phase signal periods, the transmission mode can be identified without using a high-performance filter to extract the frequency signal. , the practical effect is extremely large. Furthermore, since a high-performance filter is not required, it is extremely effective in that an inexpensive identification circuit can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a facsimile transmission mode identification device according to the present invention, FIGS. 2 to 7 are explanatory diagrams of the operation of FIG. 1, and FIG. A waveform diagram showing the input phase signals of four types of transmission modes, Fig. 3 is a time chart for explaining the operation of the detection section in the block diagram shown in Fig. 1, and Fig. 4 is shown in Fig. 2A. FIG. 5 is a time chart showing the operation of each part in FIG. 1 when the signal shown in FIG. 2B is input. FIG. 6 is a time chart showing the operation of each part in FIG. FIG. 2 is a time chart showing the operation of each part in FIG. 1 when the signal shown in C is input, and FIG. 7 is an input signal waveform diagram in the white feed mode and black feed mode. DESCRIPTION OF SYMBOLS 1... Linear detection circuit, 2... Counter/timer circuit, 3A-3D... Detection section, 4A-4D... Mode discrimination counter, 5A-5D, 6A-6D... Memory circuit, 7A-7D... Selection confirmation pulse circuit.

Claims (1)

[Scope of utility model registration request] The envelope signal of the input signal is extracted in a facsimile transmission mode identification device that automatically identifies the other party's transmission mode on the receiver side based on the phase signal sent from the transmitter to perform phase matching before transmitting the image signal. A linear detection circuit performs a timing operation while the envelope signal from this linear detection circuit is supplied as an enable signal, and creates a prescribed time width that defines the length of continuous time of the envelope signal for each transmission mode. A counter/timer circuit that sequentially outputs two signals, and detects that the envelope signal ends within a specified time width period generated by the two signals from the counter/timer circuit and outputs a corresponding detection pulse. A facsimile transmission mode identification device comprising: a plurality of detection units, and a plurality of mode discrimination counters that count the output pulses of each of these detection units and output a transmission mode identification signal when the count value reaches a certain number. .