JP2682213B2 - Extension incoming response monitoring circuit of button telephone device and monitoring method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an incoming call response monitoring circuit of a FAX accommodation extension in a key telephone device and a monitoring method thereof.

(Prior Art) FIG. 3 is a circuit diagram showing a configuration of a conventional key telephone device. This particularly shows the configuration of the incoming call response monitoring circuit of the FAX accommodation extension of the key telephone device. In the figure,
In the case of a facsimile accommodation extension line using an electronic subscriber circuit, a tone transmission control signal from a main unit (CPU) (not shown) is supplied to a relay driver 34 to drive a relay 33. The switch parts r ₁ and r _{2 of} the relay 33 are connected to the oscillator 3
It collapses to the 7 side and a ringing signal (no ringing start signal) that is a single tone of 1300 Hz is sent to the FAX terminal device. The loop formed when this tone is transmitted is the current monitoring circuit 35, 36.
The monitoring result is sent to a main device (CPU) (not shown).

However, in the above conventional circuit configuration, the ringing sound from the exchange switch side does not pass an AC signal unless the loop is closed on the side of the facsimile terminal device (because the transistor 38 in the output stage does not turn on unless a direct current is passed). Therefore, since a signal must be directly input between the L _{1 and} L ₂ terminals by the relay, a relay having two contact systems was necessary.
Further, it was necessary to separately provide a loop monitoring circuit for detecting a DC component during tone transmission. As a result, the size of the mounted components becomes large and the board area needs to be large, making it difficult to realize the miniaturization of the device. Further, there is a problem that power consumption becomes large and a driver circuit such as a transistor is required for driving. There is also a problem in that the cost of the device increases due to the necessity of these elements.

In order to solve these problems, the present applicant has previously proposed a button telephone device that can realize circuit simplification, device miniaturization, low power consumption, and low price (Japanese Patent Application No. 18
(See specification No. 050). This example is shown in FIG. In FIG. 4, reference numeral 1 denotes an oscillator, which supplies a start signal of 1300 Hz to a first contact of an analog switch 2 which forms a switch unit for exchanging the signal. The second contact of the analog switch 2 is connected to the exchange switch side (4-wire side) (not shown) of the button telephone device that sends a tone transmission control signal at the time of activation, and its common contact is 2-wire 4-wire conversion. It is connected to the input of the following amplifier of circuit 3. The 2-wire / 4-wire conversion circuit 3 here has a normal function of converting a 2-wire signal into a 4-wire signal or vice versa. Further, the 2-wire to 4-wire conversion circuit 3 has a start signal from the oscillator 1 or an exchange switch (not shown) via the analog switch 2 in order to obtain a function of transmitting a start signal from the terminal device side to the main device side. An amplifier (-) 3a and an amplifier (+) 3b that are inputting a signal from the terminal, and an amplifier 3c that sends a start signal returned from the terminal device side (2-wire side) described below to the main device side. Is equipped with.

The outputs of the amplifiers 3a and 3b are connected to the bases of the transistors 4a and 4b, respectively, which form the output stage of the electronic subscriber circuit. The collectors of the transistors 4a and 4b are connected to the terminals L ₁ and L ₂ , respectively. Transistor 4
The emitter of a is connected to a power source (not shown) that applies a voltage + V via a resistor R _1, and the emitter of transistor 4b is grounded via a resistor R ₂ .

Between the terminal L ₁ and the terminal L _2, and the phototransistor 5a preliminary current circuit 5, and a resistor R to limit the preliminary current flowing through the circuit are connected in series, the facsimile machine 7 as further terminal It is connected. The photodiode 5b, which is coupled to the phototransistor 5a via light, is
One end thereof is grounded via a resistor R ₃ , and the other end thereof is connected to a main device (CPU 11) which sends out a tone sending control signal.

The emitter of the transistor 4b is connected to the non-inverting input of the current monitoring circuit 6 including a comparator. A reference voltage is input to the inverting input of the current monitoring circuit 6. This reference voltage is a voltage + V from a power source (not shown)
It is divided by R ₄ and R ₅ . Current monitor circuit 6
Sends a loop supervisory signal of logic level 1 to the main device (CPU 11) when the voltage level at the emitter of the transistor 4b exceeds the reference voltage.

Here, the 2-wire / 4-wire conversion circuit 3, the transistors 4a and 4
b and the current monitoring circuit 6 are circuits that function as an electronic subscriber circuit unit. Reference numeral 11 is a CPU, which is usually arranged in the main unit of the key telephone device.

Next, the operation when activating the facsimile device 7 will be described. First, when the tone sending control signal is sent from the CPU 11, a current due to this is passed through the diode 5b. For this reason, the photodiode 5b emits light to turn on the phototransistor 5a, and activates the transistors 4a and 4b. Further, by sending the tone sending control signal, the analog switch 2 is switched to the opposite side of the illustrated position,
A starting signal of 1300 Hz is input to the amplifiers 3a and 3b from the oscillator 1 via the analog switch 2. Amplifiers 3a and 3b
The activation signal from is input to the transistors 4a and 4b, and a tone is sent to the terminal device side. Further, their collector outputs are input to the amplifier 3c. The amplifier 3c returns the collector output from the transistors 4a and 4b to the main device side as a start signal.

The current monitoring circuit 6 also monitors the emitter voltage of the transistor 4b and sends a loop monitoring signal having a corresponding voltage value to the CPU 11.

FIG. 5 is a conventional fax response (off-hook) detection flowchart. This shows the fax response detection operation by the CPU 11 in FIG.

First, the counter A in the CPU 11 is cleared (step 5
01). Next, the CPU 11 sends a calling signal (tone transmission control signal)
Is sent. The analog switch 2 is switched by setting this tone transmission control signal to a high level or a low level, and a 1300 Hz single tone (non-activation start signal) is transmitted from the oscillator 1 (step 502). At the same time, a current is supplied to the preliminary current circuit 5.

Next, the CPU 11 checks whether or not there is a FAX loop by a timer interrupt (step 503), and if yes, counts up the counter A (step 504) until the counter value A reaches the specified value n (step 505). , Steps 503 and 504 are repeated. Then, it is detected as a fax response (off-hook) (step 506).

(Problems to be solved by the invention) However, in the circuit of FIG. 2, the loop current at the time of trapping the fax is I ₁ , the reserve current is I ₂ , and the threshold current of the current monitoring circuit for detecting the response of the fax is If I ₃ is set, I ₂ <I ₃ <I ₁ cannot be operated normally. Where I ₁ is L ₁ −
It varies depending on the line resistance between faxes and the direct current resistance inside the fax, and I ₃ has the property that it cannot be made too large due to the noise margin. Furthermore, I ₂ is influenced by the transmission efficiency of the photocoupler, and it is necessary to select parts to stabilize I ₂ . Then, there was a problem that the price of the component parts increased.

In addition, the normal electronic subscriber circuit is designed (or integrated into an IC) so that stable characteristics can be obtained when a current of about 20 mA (I ₃ ) flows in the loop created by the FAX terminal side. In (I ₂ ), the passage loss of the 2-wire to 4-wire conversion circuit is large, and the fluctuation of the characteristics of the output stage transistor is greatly affected, and the fluctuation of the fax start signal sound level is large, and the noise is large because of the large loss. There was a problem of reducing the margin.

An object of the present invention is to solve such conventional problems,
Increase the resistance value of the preliminary current, increase the incoming signal,
It is an object of the present invention to provide an extension incoming call response monitoring circuit for a button telephone device and a monitoring method thereof, which eliminates the fact that the facsimile device cannot be used due to line loss even if the installation position of the facsimile device is far from the button telephone device.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the extension incoming response monitoring circuit of the key telephone device of the present invention is a two-line signal converting a two-line signal of the terminal device side into a four-line signal of the main device side. 4-wire conversion circuit, and 2
An activation signal which is connected to the 4-wire transmission side of the 4-wire conversion circuit and which sends a start signal for activating the terminal device to the 2-wire 4-wire conversion circuit in response to a tone transmission control signal from the main device. A spare connected to the signal transmission circuit and the two-wire side of the two-wire to four-wire conversion circuit and supplying a preliminary current to the terminal device for applying the activation signal to the terminal device in response to the tone transmission control signal. In an extension incoming call response monitoring circuit in a key telephone device, comprising a current circuit, a signal stopping means for intermittently stopping the activation signal for a predetermined time, and a connected terminal device for the time stopped by the signal stopping means. It is characterized in that a monitoring means for monitoring the loop state for a predetermined time is provided.

Further, a method of monitoring an extension incoming response of a key telephone device according to the present invention comprises a 2-wire 4-wire conversion circuit for converting a 2-wire signal of a terminal device into a 4-wire signal of a main device, and the 2-wire 4-wire conversion circuit. Four
An activation signal transmission circuit connected to the line transmission side and transmitting an activation signal for activating the terminal device to the 2-wire 4-wire conversion circuit in response to a tone transmission control signal from the main device; A spare current circuit, which is connected to the two-wire side of the wire-to-four-wire conversion circuit, and which supplies to the terminal device a preliminary current for applying the activation signal to the terminal device in response to the tone transmission control signal. In the extension call response monitoring circuit in the key telephone device, the CPU in the main device intermittently stops the activation signal for a predetermined time, and the loop of the connected terminal device at the time stopped by the timing created by the CPU It is characterized by monitoring the condition for a predetermined time.

(Operation) In the present invention, a signal stopping means for intermittently stopping the activation signal for a predetermined time, and a monitoring means for monitoring the loop state of the connected terminal device for the time stopped by the signal stopping means for a predetermined time. Since the resistance value of the preliminary current circuit can be increased by providing the above, it is possible to prevent the variation in the signal level.

Further, in the present invention, the CPU in the main device intermittently stops the activation signal for a predetermined time, and the loop state of the connected terminal device at the time of the stop created by the CPU for a predetermined time. Monitor.

(Example) Hereinafter, one example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an extension incoming call response monitoring circuit of a key telephone device showing a first embodiment of the present invention.

In FIG. 1, 1 is a start signal for facsimile (1300
(Oscillator single tone) oscillator, 2 analog switch, 3 2-wire 4-wire conversion circuit, 4 transistor, 5 preliminary current circuit, 6 current monitoring circuit, 7 facsimile machine, 8 fax loop monitoring circuit, Reference numeral 9 is a timing generation circuit, and 10 is a preliminary current limiting circuit. The timing generation circuit 9 includes a binary counter 91, D flip-flops 92, 93, X.
It is composed of an OR gate 94 and an inverter 95 and generates various timings. FIG. 2 shows these timing charts. A to J in FIG. 2 indicate timings in A to J in FIG.

In the first embodiment, by adding the FAX loop monitoring circuit (for example, D flip-flop) 8, the timing generation circuit 9, and the preliminary current limiting circuit (for example, AND gate) 10 to the configuration of FIG. Since the resistance R of the circuit 5 can be made smaller than the conventional one, the current flowing through the resistance R can be made large, and the incoming signal to the facsimile device can be made large, it is possible to prevent malfunction of the device due to line loss.

 The operation of the first embodiment will be described below.

As shown in FIG. 1, a FAX loop monitoring circuit 8 is provided on the output side of the current monitoring circuit 6, and the FAX loop monitoring circuit 8 monitors the input from the current monitoring circuit 6 according to the timing from the timing generation circuit 9. Output as a signal. Further, the photocoupler of the backup current circuit 5 is switched at another timing from the same timing generation circuit 9.

When sending a start signal to the facsimile apparatus 7, it is sent from the oscillator 1 to the facsimile apparatus 7 through the analog switch 2 and the 2-wire to 4-wire conversion circuit 3. in this case,
It becomes possible to send a signal to the facsimile apparatus 7 by supplying a current to the backup current circuit 5 and turning on the transistor 4 at the output stage of the computerized subscriber circuit unit. In the first embodiment, the current flowing through the backup current circuit 5 is flowed at the timing shown in the timing chart H, the activation signal is sent during the high level, and stopped during the low level.

At this time, if the resistance R is set so that the preliminary current I ₂ flowing when the photocoupler of the preliminary current circuit 5 is ON (high level) is larger than the threshold current I ₃ , the output of the current monitoring circuit 6 for detecting the response of the facsimile apparatus is output. The same waveform as H can be obtained as shown in the timing chart I.

Further, a FAX loop monitoring circuit (here, a D flip-flop) 8 is installed on the output side of the current monitoring circuit 6 so that the I level is output at the timing of the timing chart F.

Here, the OFF time (t) of the activation signal transmission timing H is set to 40 μs as a time that does not affect the frequency of the activation signal (1300 Hz). In addition, by setting the cycle of timing charts H and F to 10.24 ms and delaying F by 20 μs, the output signal of the current monitoring circuit 6 is changed every 10.24 ms.
Monitor and output to J.

As a result, the facsimile device 7 detects the activation signal sent at the timing of H, and responds to it to close the loop between L ₁ and L ₂ (for example, a timing chart arrow).
Then, thereafter, the output of the current monitoring circuit 6 remains at the high level. Therefore, the output of the FAX loop monitoring circuit 8 is F
The level changes from low level to high level at the timing next to, indicating that the facsimile apparatus 7 has responded.

If the start signal stop time t is made sufficiently short with respect to the start signal cycle of 1300 Hz (40 μs in this example), there is no problem with the influence on the start signal receiving function on the FAX side.

It should be noted that in the first embodiment described above, a specific timing value was set and described, but it goes without saying that the present invention is not limited to this.

FIG. 6 is a FAX response (off-hook) detection flowchart showing the second embodiment of the present invention. This is the CP in Figure 4
The fax response detection operation by U11 is shown. In the second embodiment, the function equivalent to that of the first embodiment is realized by changing the program of the CPU 11 without adding the circuit as in the first embodiment. The operation of the second embodiment will be described below with reference to the flow of FIG.

First, the counter A in the CPU 11 is cleared (step 1
01). Next, the CPU 11 sends a calling signal (tone transmission control signal)
Is sent. The tone switch control signal is set to the high level or the low level to switch the analog switch 2 so that the oscillator 1 outputs a single tone of 1300 Hz (a silent start signal) (step 202). At the same time, a current is supplied to the preliminary current circuit 5.

Next, the CPU 11 checks whether or not there is a FAX loop by a timer interrupt (step 103), and if yes, counts up the counter A (step 104) until the counter value A reaches the specified value n (step 105), The processing of steps 103 and 104 is repeated. When the counter value A reaches the specified value n,
The CPU 11 stops sending the calling signal (step 106). Next, create a timing signal of 40 μs, for example (step
107), when there is a fax loop (step 108), it is detected as a fax response (off-hook) (step 109).

If there is no FAX loop in step 108, the process returns to step 101.

Since the second embodiment can be realized without adding a circuit, there is an advantage that it can be realized at a lower cost than the first embodiment.

(Effects of the Invention) As described above, according to the present invention, the detection of the incoming response of the facsimile device is stopped within a range that does not affect the activation signal, and the loop current level during that period is monitored to detect the facsimile device. By changing to the method of detecting the response, the standby current for allowing the activation signal to pass through the electronic subscriber circuit unit is the loop current value in the current monitoring circuit 6,
Also, the value can be set to a large value without being limited by the current that flows when the loop of the facsimile apparatus is captured. As a result, a stable start signal with a high S / N ratio and a large level margin can be sent to the facsimile apparatus, and improvement in quality can be expected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an extension incoming response monitoring circuit of a button telephone device showing a first embodiment of the present invention, FIG. 2 is a timing chart of FIG. 1, and FIGS. 3 and 4 are conventional button telephones. FIG. 5 is a configuration diagram of an extension incoming call response monitoring circuit of the apparatus, FIG. 5 is a conventional fax response (off-hook) detection flowchart, and FIG. 6 is a fax response (off-hook) detection flowchart showing a second embodiment of the present invention. 1: Oscillator, 2: Analog switch, 3: 2-wire to 4-wire conversion circuit, 4a, 4b: Transistor, 5: Preliminary current circuit, 6: Current monitoring circuit, 7: Facsimile machine, 8: Fax loop monitoring circuit, 9: Timing generation circuit, 10: Preliminary current limiting circuit, 11: CPU.

Claims (2)

(57) [Claims] 1. A two-wire to four-wire conversion circuit for converting a two-wire signal on the terminal device side into a four-wire signal on the main device side, and a four-wire transmission side of the two-wire to four-wire conversion circuit connected to the main device. To a 2-wire 4-wire conversion circuit, and a 2-wire side of the 2-wire 4-wire conversion circuit. In an extension incoming call response monitoring circuit in a key telephone device, which is connected, and includes a backup current circuit that supplies a backup current for applying a startup signal to the terminal device in response to the tone transmission control signal to the terminal device. A signal stop means for intermittently stopping the activation signal for a predetermined time, and a monitoring means for monitoring a loop state of the connected terminal device for a predetermined time during the time stopped by the signal stop means. Button telephone equipment Extension call response monitoring circuit. 2. A 2-wire 4-wire conversion circuit for converting a 2-wire signal on the terminal device side into a 4-wire signal on the main device side, and a 4-wire transmission side of the 2-wire 4-wire conversion circuit, the main device being connected. To a 2-wire 4-wire conversion circuit, and a 2-wire side of the 2-wire 4-wire conversion circuit. In an extension incoming call response monitoring circuit in a key telephone device, which is connected, and includes a backup current circuit that supplies a backup current for applying a startup signal to the terminal device in response to the tone transmission control signal to the terminal device. The CPU in the main device intermittently stops the activation signal for a predetermined time, and the loop state of the connected terminal device at the time of the stop is monitored for a predetermined time according to the timing created by the CPU. Button telephone device Extension incoming response monitoring method.