JPH0497694A - Extension incoming reply monitoring circuit and monitoring method for key telephone set - Google Patents

Abstract

PURPOSE:To prevent dispersion in a FAX start signal level by stopping an incoming signal reply detection of a facsimile equipment to an extent not giving an effect onto a start signal, monitoring a loop current level for the time so as to detect the reply of the facsimile equipment. CONSTITUTION:An extension incoming call reply monitor circuit of a key telephone set consist of an oscillator 1, an analog switch 2, a 2/4 wire conversion circuit 3, transistors(TRs) 4a, 4b, a standby current circuit 5, a current monitor circuit 6, a facsimile equipment 7, a FAX loop monitor circuit 8, a timing generating circuit 9, a standby current limit circuit 10 and a CPU 11. Then a start signal is intermittently stopped by the CPU 11 in a master set for a prescribed time and the loop state of a terminal equipment connected for a stop time in the timing generated by the CPU 11 is monitored for a prescribed time. Thus, dispersion in the level of the FAX drive signal is not caused.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an incoming call response monitoring circuit for a FAX accommodating extension line in a button telephone device and a monitoring method thereof.

(Prior Art) FIG. 3 is a circuit diagram showing the configuration of a conventional key telephone device. This particularly shows the configuration of the incoming call response monitoring circuit for the FAX accommodating extension of the key telephone device. In the same figure,
In the case of a facsimile accommodating extension using an electronic subscriber circuit, a tone sending control signal from a main unit ((:PU) not shown) is supplied to a relay driver 34,
drive. Then, the switch section rl+ of the relay 33
r2 falls to the oscillator 37 side, and a 1300 Hz single tone ringing signal (non-ring activation signal) is sent to the FAX terminal device. The loop formed when this tone is sent out is monitored by current monitoring circuits 35 and 36, and the monitoring results are sent to a main unit (CPU) not shown.

However, in the above-mentioned conventional circuit configuration, unless the facsimile terminal closes the loop for the ringing tone from the exchange switch side (because the transistor 38 in the output stage will not turn on unless DC current flows), the AC signal will not pass through. Therefore, it was necessary to input a signal directly between the L□ and L2 terminals using a relay, so a relay with two systems of contacts was required. It was also necessary to separately provide a loop monitoring circuit for detecting the DC component during tone transmission. Therefore, the mounted components become large and a large board area is required, making it difficult to realize miniaturization of the device. Further, there is a problem in that power consumption increases and a driver circuit such as a transistor is required for driving. There is also the problem that the cost of the device increases due to the need for these elements.

In order to solve these problems, the present applicant has previously proposed a button telephone device that can simplify the circuit, reduce the device size, reduce power consumption, and reduce the price (Patent application No. 18
(See specification No. 050). An example of this is shown in FIG. In FIG. 4, an oscillator 1 supplies a 1300 Hz activation signal to the first contact of an analog switch 2 forming an exchange switch section. The second contact of the analog switch 2 is on the exchange switch side (not shown) of the button telephone device that sends out the tone sending control signal at startup (4-wire side).
The common contact is connected to the input of the following amplifier of the 2-wire/4-wire conversion circuit 3. The 2-wire 4-wire conversion circuit 3 here is 21! 4 from the signal! It has the usual function of converting to an I signal and vice versa.

Furthermore, the 2-wire 4-wire conversion circuit 3 receives a start signal from the oscillator 1 via the analog switch 2 or an exchange switch (not shown) in order to obtain a function of sending a start signal from the terminal device side to the main device side. The amplifier inputting the signal from
-) 3a, an amplifier (+) 3b, and an amplifier 3c that sends an activation signal returned from the terminal device side (two-line side) to the main device side, which will be described below.

The outputs of the amplifiers 3a and 3b are respectively connected to the bases of transistors 4a and 4b forming the output stage of the electronic subscriber circuit. Transistors 4a, 4b
The collectors of are connected to terminals R2 and R2, respectively. The emitter of the transistor 4a is connected via a resistor R1 to a power supply (not shown) that applies a voltage +V, and the emitter of the transistor 4b is grounded via a resistor R2.

A phototransistor 5a of a preliminary current circuit 5 and a resistor R for limiting the preliminary current flowing through the circuit are connected in series between terminals L1 and L2, and a facsimile device 7 is also connected as a terminal device. There is. The photodiode 5b coupled to the phototransistor 5a via light has its negative end grounded via the resistor R5, and the other end connected to the main device (CPUII) that sends out the tone sending control signal.
)It is connected to the.

The emitter of the transistor 4b is connected to a non-inverting input of a current monitoring circuit 6 consisting of a comparator. A reference voltage is input to the inverting input of the current monitoring circuit 6. This reference voltage is obtained by dividing voltage +■ from a power supply (not shown) by resistors R4 and R8. When the voltage level at the emitter of the transistor 4b becomes equal to or higher than the reference voltage, the current monitoring circuit 6 sends a loop monitoring signal having a logic level of 1 to the main device (CPLIII).

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 section. Also, ]1 is the CPU, and usually,
It is located in the main unit of the button telephone device.

Next, the operation when starting up the facsimile machine 7 will be explained. First, when a tone sending control signal is sent from CPU i 1, a current flows through the diode 5b. For this purpose, the photodiode 5b emits light, turning on the phototransistor 5a and putting the transistors 4a and 4b into operation. Further, by sending the tone sending control signal, the analog switch 2 is switched to the opposite position from the illustrated position, so that a 1300 Hz starting signal is input from the oscillator to the amplifiers 3a and 3b via the analog switch 2. Activation signals from amplifiers 3a and 3b are input to transistors 4a and 4b, and a tone is sent to the terminal device side. Furthermore, their collector output or amplifier 3C
is input. Amplifier 3C includes transistors 4a and 4
The collector output from b is returned to the main device side as a start signal.

Further, the current monitoring circuit 6 monitors the emitter voltage of the transistor 4b and sends it to a loop monitoring signal cputi having a corresponding voltage value.

FIG. 5 is a conventional FAX response (off-hook) detection flowchart. This is the F according to CPIJII in Figure 4.
AX response detection operation is shown.

First, counter A in CPU II is cleared (step 501). Next, the CPU II sends out a paging signal (tone sending control signal). By setting this tone sending control signal to high or low level, the analog switch 2 is switched, and the oscillator sends out a single tone of 1300 Hz (no-sound activation signal) (step 50).
2). At the same time, current is supplied to the preliminary current circuit 5.

Next, CPIJII uses a timer interrupt to check whether there is a FAX loop (step 503), and if there is, increments counter A (step 504) until counter value A reaches the specified value n (step 505).
, repeats the processing of steps 503 and 504. and,
FAX response (off-hook) is detected (step 506
).

(Problem to be solved by the invention) However, in the circuit shown in Fig. 2, the loop current at the time of loop acquisition of FA and If is set to 13, normal operation is not possible unless i2<i,<It are set. Here, the line resistance 11 varies depending on the line resistance between -FAX and the DC resistance inside the FAX, and the line resistance cannot be increased too much due to the noise margin. Furthermore, (2) was affected by the transmission efficiency of the photocoupler, etc., and it was necessary to select parts, etc. to stabilize (2). Then, there was a problem in that the price of component parts rose accordingly.

In addition, normal electronic subscriber circuits are designed (or integrated into ICs) in such a way that stable characteristics are obtained when a current of about 20 mA (I3) flows through the loop created by the FAX terminal, and the current is smaller than this (I3). ■In 2), the passing loss of the 2-wire 4-wire conversion circuit is large, and it is also greatly affected by variations in the characteristics of the output stage transistors, resulting in large variations in the level of the FAX start signal sound and noise due to the large loss. There was a problem in that the margin was reduced.

The purpose of the present invention is to solve these conventional problems, increase the resistance value of the preliminary current, increase the incoming signal, and prevent line loss even if the facsimile machine is installed far away from the key telephone device. An object of the present invention is to provide an extension call response monitoring circuit for a key telephone device and a method for monitoring the same, which eliminates the possibility of the telephone being unusable.

(Means for Solving the Problems) In order to achieve the above object, the extension call response monitoring circuit of the key telephone device of the present invention has a 2-wire incoming call response monitoring circuit for converting a 2-wire signal on the terminal device side into a 4-wire signal on the main device side. A 4-wire conversion circuit is connected to the 4-wire transmitting side of the 2-wire 4-wire conversion circuit, and outputs an activation signal for activating a terminal device in response to a tone transmission control signal from the main device. A start signal sending circuit that sends out to the 4-wire conversion circuit is connected to the 2-wire side of the 2-wire 4-wire conversion circuit, and the start signal is applied to the terminal device in response to the 1...-on sending control signal. In the extension call response monitoring circuit for a button telephone device, the extension call response monitoring circuit includes a standby current circuit for supplying a standby current to a terminal device, and a signal stopping means for intermittently stopping the activation signal for a predetermined period of time, and the signal stopping means. The present invention is characterized in that it includes a monitoring means for monitoring the loop state of the connected terminal device for a predetermined period of time during which the device is stopped.

Further, the extension call response monitoring method for a key telephone device of the present invention includes a 2-wire 4-wire conversion circuit that converts a 2-wire signal on the terminal device side into a 4-wire signal on the main device side; an activation signal sending circuit connected to the 4-wire transmission side and configured to send 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 standby current circuit connected to the 2-wire side of the 2-wire 4-wire conversion circuit, and supplying a standby current to the terminal device for applying a start signal to the terminal device in response to the tone sending control signal. , in an extension call response monitoring circuit in a button telephone device, the CPU in the main device intermittently stops the activation signal for a predetermined period of time, and the timing created by the CPU is used to control the connected terminal device during the stopped time. The feature is that the roof condition is monitored for a predetermined period of time.

(Function) The present invention includes a signal stopping means for intermittently stopping the activation signal for a predetermined period of time, and a monitoring means for monitoring a loop state of a connected terminal device for a predetermined period of time during which the activation signal is stopped by the signal stopping means. By providing this, it is possible to increase the resistance value of the preliminary current circuit, thereby preventing variations in signal level.

Further, in the present invention, the activation signal is intermittently stopped for a predetermined period of time by the CPU in the main device, and the loop state of the connected terminal device is maintained for the predetermined period of time according to the timing created by the CPU. Monitor.

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

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

In FIG. 1, 1 is a facsimile activation signal (130
0Hz single tone) oscillator, 2 is an analog switch, 3 is a 2-wire 4-wire conversion circuit, 4 is a transistor,
5 is a preliminary current circuit, 6 is a current monitoring circuit, 7 is a facsimile machine, 8 is a FAX loop monitoring circuit, 9 is a timing generation circuit, and 10 is a preliminary current limiting circuit. The timing generation circuit 9 includes a binary counter 91. It is composed of D flip-flops 92 and 93, an XOR gate 94, and an inverter 95, and generates various timings. These timing charts are shown in FIG. A-J in Figure 2
1 shows the timing at A-J in FIG.

In the embodiment of the bookcase 1, the configuration shown in FIG.
By adding 0, the resistance R of the preliminary current circuit 5 is made smaller than before, and the current flowing through this resistance R is increased.
Since the incoming signal to the facsimile machine can be increased, malfunction of the machine due to line loss can be prevented.

The operation of the embodiment of the bookcase 1 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 this FAX loop monitoring circuit 8 monitors the input from the current monitoring circuit 6 using the timing from the timing generation circuit 9. Output as a signal. Further, the photocoupler of the preliminary current circuit 5 is switched by another timing from the same timing generation circuit 9.

When sending a start signal to the facsimile machine 7, the oscillator 1 passes through the analog switch 2 and sends it to the 2-wire 4-wire conversion circuit 3.
The data is sent to the facsimile machine 7 through the fax machine. In this case, a signal can be sent to the facsimile machine 7 by passing a current through the preliminary current circuit 5 and turning on the transistor 4 at the output stage of the electronic subscriber circuit section. In the embodiment of the bookcase 1, the current is passed through the preliminary current circuit 5 at the timing shown in the timing chart H, and a start signal is sent out while it is at a high level, and stopped when it is at a low level.

At this time, if the resistor R is set so that the preliminary current (2) flowing during the photocube 908 (high level) of the preliminary current circuit 5 is greater than the threshold current I3, the output of the current monitoring circuit 6 for detecting the response of the facsimile machine is As shown in the timing chart (2), the same waveform as H is obtained.

Furthermore, a FAX roof monitoring circuit (here, a D flip-flop) 8 is installed on the output side of the current monitoring circuit 6, and is configured to output the level (3) at the timing shown in the timing chart F.

Here, the OFF time (
1) is set to 40 μs as a time that does not affect the frequency of the activation signal (130 Hz). Also, the period of timing charts H and F is 10.24m5, and F is 20m5.
By delaying by μs, the output signal of the current monitoring circuit 6 is monitored every 10.24 m5.1. Output to J.

As a result, the facsimile machine 7 detects the activation signal sent at the timing of H, responds, and LI+T, 2
When the loop between is closed (for example, a timing chart arrow), the output signal of the current monitoring circuit 6 remains at a high level from then on. For this purpose, the FAX loop monitoring circuit 8
The output of F changes from low level to high level at the next timing of F, indicating that the facsimile machine 7 has responded.

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

Although the first embodiment has been described by setting specific timing values, it goes without saying that the present invention is not limited to this.

FIG. 6 is a FAX response (off-hook) detection flowchart showing a second embodiment of the present invention. This is C in Figure 4.
It shows the FAX response detection operation by the PU 11. In the embodiment of the bookcase 2, a CP with the same function as the first embodiment is used, without adding a circuit like the first embodiment.
This was made possible by changing the U11 program. below,
The operation of the embodiment of the bookcase 2 will be explained according to the flow shown in FIG.

First, counter A in the CPU 11 is cleared (step 101). Next, the CPU 11 sends out a calling signal (tone sending control signal). By setting this tone sending control signal to high or low level, the analog switch 2 is switched, and the oscillator 1 sends out a single tone of 1300 Hz (no-sound activation signal) (Step 1)
02). At the same time, current is supplied to the preliminary current circuit 5.

Next, the CPU 11 uses a timer interrupt to check whether there is a FAX loop (step 103), and if there is, increments the counter A (step 104) until the counter value A reaches the specified value n (step 105). Repeat steps 103 and 104. Then, when the counter value A reaches the specified value n, the CPU 11 stops sending out the calling signal (step 106). Next, step 10 to create a timing signal of, for example, 40 μs.
), FAX )L, - When there is a (step 108)
detects a FAX response (off-hook) (step 10)
9).

In step 108, if there is no FAX loop, the process returns to step 101.

The second embodiment can be realized without adding any circuits, so it has the advantage that it can be realized at a lower cost than the first embodiment.

(Effects of the Invention) As explained above, according to the present invention, incoming call response detection of the facsimile machine is stopped within a range that does not affect the activation signal, and the loop current level is monitored during that time. By changing the method to detect the response, the preliminary current for passing the start signal or the electronic subscriber circuit section is limited to the loop detection current value in the current monitoring circuit 6 and the current flowing when the facsimile machine captures the loop. It can be a large value that will never be used. This makes it possible to send a stable start signal with a high S/N ratio and a large level margin to the facsimile machine.
We can expect an improvement in quality.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an extension call response monitoring circuit of a button telephone device according to a first embodiment of the present invention, FIG. 2 is a timing chart of FIG. 1, and FIGS. 3 and 4 are diagrams of a conventional button telephone. FIG. 5 is a conventional FAX response (off-hook) detection flowchart; 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
4-wire conversion circuit, 4a, 4b: transistor, 5: preliminary current circuit, 6: current monitoring circuit, 7: facsimile device, 8: FAX loop monitoring circuit, 9: timing generation circuit, 10: preliminary current limiting circuit, 11 :CPU. Conventional FAX response (off-hook) detection flow Figure 5

Claims (2)

[Claims] (1) A 2-wire 4-wire conversion circuit that converts a 2-wire signal on the terminal device side into a 4-wire signal on the main device side; a startup signal sending circuit that sends a startup signal for starting a terminal device to the two-wire and four-wire conversion circuit in response to the tone transmission control signal; , a preliminary current circuit for supplying a preliminary current to the terminal device for application of the activation signal to the terminal device in response to the tone sending control signal; A button characterized in that it is provided with a signal stopping means for intermittently stopping a start signal for a predetermined period of time, and a monitoring means for monitoring a loop state of a connected terminal device for a predetermined period of time during which the activation signal is stopped by the signal stopping means. Extension call response monitoring circuit for telephone equipment. (2) A 2-wire 4-wire conversion circuit that converts a 2-wire signal on the terminal device side into a 4-wire signal on the main device side; a startup signal sending circuit that sends a startup signal for starting a terminal device to the two-wire and four-wire conversion circuit in response to the tone transmission control signal; , a preliminary current circuit for supplying a preliminary current to the terminal device for application of the activation signal to the terminal device in response to the tone sending control signal; A button characterized in that the activation signal is intermittently stopped for a predetermined period of time by a CPU in the main device, and the loop state of the connected terminal device at the time of the stop is monitored for a predetermined period of time based on the timing created by the CPU. A method for monitoring extension call response of telephone equipment.