JPS6012857A - Signal identifying circuit of network control device - Google Patents

Abstract

PURPOSE:To identify various receiving signals precisely without malfunction with a simple constitution by using an off-hook detecting circuit and a call signal detecting circuit in common and multiplying the frequency of a call signal. CONSTITUTION:When a calling AC signal arrives at a subscriber's line 100 under the on-hook state of a telephone set, current flows into LEDs D1 and D2 alternately and the collectors of TRs Q1, Q2 are alternately turned on and off. Therefore, the call AC signal is multiplied by twice and inputted to an inverter 28. The output of the inverter 28 is inputted to a tone detector 32 and detected as a call signal by a CPU38. When the telephone set is turned to the off-hook state, DC current flows in one direction. Consequently, any one of diodes D1, D2 is steadily turned on, the collector of the TRQ1 or Q2 is turned to the low level and an off-hook detecting signal with the H level is outputted by the output of the inverter 28. Subsequently, a dial pulse is outputted from the output of the TRQ1 by dialing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal identification circuit for detecting DC and AC reception signals in a network control device such as a facsimile.

The network control device, which is connected between the subscriber line and the telephone and switches the connection between the telephone and a terminal device such as a facsimile machine, detects whether the hook of the telephone is ON or OFF. The function to detect the calling AC number 43 is essential.

An example of a conventional network control device having these functions is shown in FIG. 2 is a DC loop detection circuit made of a relay or a photocoupler; 4 is a DC current blocking capacitor for blocking a DC current; 6 is a rectifier bridge; 8 is a relay or photocoupler.
Connect the subscriber line 100 from the central office to the telephone side connection terminal 200
and a facsimile terminal device 50; 50 is a facsimile terminal device;

When you take the phone off-hook, the subscriber line io.

Off-hook is detected by the detection circuit 2 due to the DC loop current flowing through. At this time, the detection circuit 8 does not operate because the DC blocking capacitor 4 blocks the DC Rougemi flow.

Next, when a calling AC signal arrives from the network through the subscriber line ioo, it passes through the DC blocking capacitor 4. Therefore, the detection circuit 8 operates through the rectifier bridge 6, and the ON signal output from the detection circuit 8 is transmitted to the contact IQ a *
It is used for various necessary controls such as i 0 b switching.

In such a conventional method, two
This method requires a circuit, which is disadvantageous in terms of device configuration, space, and cost, and it also has drawbacks such as a large number of parts.

Furthermore, the AC detection circuit 8 also responds to dial pulses generated by the telephone at its own station, resulting in malfunctions.

To solve this problem, the NCU circuit described in Japanese Patent Laid-Open No. 57-31256 uses a monitoring circuit that responds to both the line's DC loop current and the calling AC signal. However, it still has a complicated configuration, requiring many time constant circuits with delicate adjustments.

An object of the present invention is to eliminate the drawbacks of the prior art and provide a signal identification circuit for a network control device that can reliably identify various received signals with a simple configuration and without malfunction. shall be.

The configuration of the present invention will be described below based on one embodiment.

In an embodiment of the signal identification circuit of a network control device according to the present invention,
A pair of photocouplers 20 are inserted into one side, for example, the R line, of a subscriber line 100 extending from a central office to a telephone (not shown). In this embodiment, a pair of photodiodes DI and D2 are connected with opposite polarities to each other as shown, from the break side of the contact 10b on the R line to the L2 line of the telephone. 7 Otoguio, Do Di and D
A capacitor 22 and a varistor 24 are connected to both ends of the capacitor 2 to protect them from reverse breakdown voltage.

Each emitter of each phototransistor Ql and Q2 of photocoupler pair 20 is grounded.

Moreover, its collector is connected to a positive DC power supply V via a resistor 26 on the one hand. C and, on the other hand, to two inverters 28 and 30, respectively, to human power 27 and 29. Inverters 28 and 30 each input 27 or 2
9 exceeds a predetermined threshold, the corresponding output 31 or 33
A Schmitt trigger inverter with a waveform shaping function that reduces the voltage to a low level may be used.

A tone detector 32 is connected to the output 31 of the inverter 28.
is connected. The tone detector 32 is a circuit that detects various signal tones such as a ringing signal, as will be described later, and its output 35 contains data representing the duration of each detected signal tone, for example, as a digital signal. The data is output to a processing unit (CPU) 48 in the form of data. The output 33 of inverter 30 is also provided to CPU 48 as a high level signal indicating off-hook detection.

The CPU A 8 is a digital processing device that controls the entire network control device or the entire system including the facsimile terminal device 50, and only the parts necessary for understanding the present invention are shown.

The CPU 48 controls the tone detector 32 via a connecting line 37 and the switching contacts 10a and 10'b via a control line 49, symbolized by an arrow 49.

First, we will explain the operation when the telephone is on-hook and in an idle state where no calling AC signal is received from the central office. In this state, the subscriber loop is not closed, and no current flows through the diodes DI and D2 in the two 7-channel telephone circuits 20, so that the transistors Q1 and Q2 are turned off. Therefore, the collectors of transistors Q1 and Q2 are connected to the positive power supply V. The voltage of C becomes H level, and the output of inverter 28.30 becomes L level.

Next, when the telephone is on-hook and a calling AC signal shown in FIG. 4 (4) arrives from the central office to the subscriber line 100, seven light emitting diodes D
Current flows alternately through transistors Q1 and D2, and the collector outputs of transistors Q1 and Q2 are alternately turned on and off. The collectors of the two transistors Ql and Q2 are
Since the wire 208 circuit is configured by a so-called common connection collector, for example, a normal! The 6Hz calling AC signal is doubled to 36Hz and sent to the inverter 2.
8 is input. Therefore, as shown in FIG. 4(B), the output 31 of the inverter 28 is a 36 Hz H/L level repeating pulse. The output 31 of the inverter 28 is connected to a tone detector 32, and a shaped 36Hz signal such as be done.

By the way, in the idle state, the time tl (Fig. 4(C))
When the telephone is taken off-hook, a subscriber loop is formed and direct current flows in one direction. As a result, one of the diodes DI or D2 of the Shibea photocazolla 20 is not in a steady ON state, so the collector of one of the transistors Q1 or Q2 that has been turned on becomes a low level, and the output 33 of the inverter 30 is turned on. An off-hook detection signal at H level is output.

Next, when the dial is operated while the telephone is off-hook, one of the photodiodes D1 or D2, which is conducting, is turned on and off in response to the dial pulse. For example, in the case of a 10 pps dial pulse (Fig. 4 CD), the photodiode of one photocoupler 20, for example Dl
is repeatedly turned ON and OFF at a period of 1/1o second, while, for example, D2 is continuously in a non-conducting state. Therefore, the output of one transistor Q1 outputs the same 10 pps Norj to the inverter 28 via a wired OR combination. Similarly, when the dial pulse is 20 pps, an i9 pulse output of 20 pps appears on the output side of the photocoupler 20.

The detected i9 pulse of each dial pulse is shaped and inverted by an inverter 28, and inputted to a tone detector 32, where it can be easily distinguished from the above-mentioned calling signal.

In other words, the number of pulses detected by DialMi4rus is 10.
Hz or 20 Hz, whereas the detection pulse from the calling AC signal is 32I (z
The signal is input to the tone detector 32 as a signal. By shifting the frequency of the ringing signal detection signal away from the frequency of the dial pulse detection signal in this way, C
In the PU 48, the difference in frequency is easily identified and these signals are differentiated.

Next, the tone detector 32 will be explained. As shown in FIG. 3, the tone detector 32 includes a control signal generation circuit 40, an AND gate 42, and a reference clock generation circuit 44.
, a changeover switch 50, and a counting circuit 46. The reference clock generation circuit 44 outputs a relatively low frequency clock to an output terminal 45a, and outputs a relatively high frequency tarokk to an output terminal 45b.

By doing so, the counting circuit 46 can multiply the width of 4 pulses (of either long or short periods) by 1 with the same number of counting stages.

When the input signal from the inverter 28 in FIG. 2 enters the control signal generation circuit 40, the gate 41 is energized and the AND/DART is opened only during the period when the input signal is at the H level. A counting clock is supplied from the reference clock generation circuit 44 to the counting circuit 46. For example, in the case of calling signals and dial/guru identification operations, the CPU 4
8 connects the contact 50 to the output 45& by the control line 37,
A low frequency clock is input to the counting circuit 46. In this way, the counting circuit 46 outputs the output 3 of the inverter 28.
1 is at the H level, and outputs this counted value from the output 35 to the CPU 48. Inverter 28
When the input signal 31 from the control signal generation circuit 40 becomes L level, the control signal generation circuit 40 resets the counting circuit 46 through the lead 43 and prepares for counting the next pulse width.

Based on the output data 35 from the counting circuit 46 and the output 33 from the inverter 30, the CPU 48 clearly distinguishes the calling signal from the dial iE call and identifies off-hook. When a ringing signal is detected, the CPo 48 switches the contacts 10a and 1Ob to the facsimile IJ terminal device 50911 through the lead 49, thereby controlling the device.

According to the present invention, the configuration of the network control device can be simplified by making the off-hook detection circuit and the paging signal detection circuit common. In addition, since the frequency of the ringing signal is multiplied for identification, it is possible to prevent malfunctions caused by erroneously detecting dials and dials from your own telephone as a ringing signal, which is a drawback of the conventional method. .

Furthermore, there is no malfunction due to the number of types of telephones used or deviations in ringing signals.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the signal identification circuit of a conventional network control device; FIG. 2 is a circuit diagram showing an embodiment of the signal identification circuit of a network control device according to the present invention; FIG. FIG. 4 is a waveform diagram showing signal waveforms appearing in each part of the circuit shown in FIG. 2. Explanation of symbols of main parts 2... Loop detection circuit 4... DC blocking capacitor 6... Rectifier bridge 8... AC detection circuit 10a, 10b... Relay contact 20... Photo coupler 24... ...Protective varistor 28,30...Inverter 32...Tone detector 40...Control signal generation circuit 42...AND gate 44...Reference clock generation circuit 46...Counter circuit 48... CPU 50...Fax 7mm terminal device 100...Subscriber line 200...Telephone terminal Patent applicant: Ricoh Co., Ltd., Japan J-13J-I, Director General of the Japan Patent Office, 1981, 10J1-2P Kazuo Wakasugi, Engineer, Indication of the case, 1982 Patent Application No. 120206 2, Name of the invention, Signal identification circuit for network control equipment 3, Person making the amendment Relationship to the case Patent applicant Address: 1 Nakamagome, Ota-ku, Tokyo Chome 3-6 Name (
874) Riko Co., Ltd. -4, Agent address: Toranomon Hoju Kaikan 7#5, 1-13-4 Toranomon, Minato-ku, Tokyo 105, Subject of amendment (1) "Detailed description of the invention" column of the specification (2) Contents of amendment in column 6 of "Brief Description of Drawings" of the specification (1) Correct the statement "Continuation JIJI IIJI J to r period" in line 5 of page 6 of the specification. (2) Revise r 36HzJ on page 7, line 17 to r 32HzJ. (3) Correct r38) 1zJ to 132HzJ in line S2θ on the same page. (4) Correct r38HzJ in the third line of page 8 to r32HzJ. (5) Correct "pulse width" in the fourth line of the same page to "number of pulses corresponding to the pulse period". (6) Correct "pulse width of r period" in the 1st θ line of page 1 O to "number of pulses corresponding to the period". (7) Correct "H level" in lines 13 to 14 of the same page to "1 cycle." (8) Correct "H level" in line 15 of the same page to "1 cycle". (9) In the second and third lines of page 11, "is at H level" is corrected to "is in one period of the output pulse of". (lO) In the fifth line of the same page, correct "becomes L level" to "ends one cycle of." (11) Correct "pulse width" in line 7 of the same page to "pulse period". (12) Insert the following text between lines 16 and 17 of the same page. 5 shows another embodiment of the invention, in which the g capacitor 22 in the circuit of FIG. 2 is replaced by a resistor 10G and a
02 is provided, and the Ll and L2 lines are coupled through a resistor 104 and a capacitor 10B, but this circuit is the same as the circuit in the second A. (13) "r waveform diagram on page 12, line 15" is replaced with "waveform diagram," and FIG. 5 is a circuit diagram showing another embodiment of the present invention.
Correct. (14) Figure 5 of the drawings is added as attached. 7. List of attached documents (1) Additional drawings (Fig. 5) 1 copy

Claims (1)

[Scope of Claims] A network control device that is located between a telephone set, a terminal device, and a subscriber line, and that switches the subscriber line from the telephone set to the terminal device when a ringing signal arriving from the subscriber line is detected. The signal identification circuit includes: first directionality detection means for outputting a logic output in response to a current in one direction in the subscriber line; and a first directionality detection means having a polarity opposite to that of the first directionality detection means. a second directionality detection means that is connected to the subscriber line and outputs a logic output in response to a current in the other direction in the subscriber line; and a logical sum of the logic outputs of the first and second directionality detection means. a synthesis circuit; and signal identification means for identifying the frequency and duration of a signal output by the synthesis circuit, the signal identification means identifying an off-hook by the telephone when the logic output of the synthesis circuit continues. A signal identification circuit for a network control device, characterized in that when the logical output of the combining circuit is intermittent, the signal is 1, and a paging signal is identified from the frequency and duration of the intermittent occurrence.