JP3325187B2 - Bipolar current detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bipolar current detecting apparatus for accurately detecting a continuous signal which continuously changes in both positive and negative polarities and a discontinuous signal which changes to a constant positive value or a constant negative value. About.

[0002]

2. Description of the Related Art As a transmission system for transmitting a discontinuous signal that changes to a positive constant value or a negative constant value, there is a telegraph line for transmitting a telegraph code using a telegraph. This telegraph line
As shown in FIG. 8, the transmitting terminal 1, the signal path 2, and the receiving terminal 3
It is composed of

In the transmitting terminal station 1, DC power supplies 4a and 4b of the same configuration having output voltages having opposite polarities and one of the output voltages E ₀ and -E ₀ of the DC power supplies 4a and 4b are provided. An electric train 5 for selecting one is incorporated. On the other hand, in the receiving terminal station 3, the operating current is polarized relay 6 which is the I _D and -I _D is incorporated. The signal path 2 has an impedance 7 that fluctuates greatly due to weather, load fluctuations, and other effects.

Accordingly, as shown in FIG. 9, a discontinuous telegraph signal a which changes to a constant positive value (E ₀ ) or a constant negative value (-E ₀ ) flows through the signal path 2. As a transmission system for transmitting a continuous signal that continuously changes in both positive and negative polarities and a discontinuous signal that changes to a positive constant value or a negative constant value, for example, a water treatment plant or a water purification plant shown in FIG. And so on.

The water level sensor 8 has a water level L shown in FIG.
And outputs a detection signal b proportional to. In this case, FIG.
As shown in (a), when the water level L is the reference water level L _S , the value of the output voltage V is set to 0 volt, and the reference water level L _S
When it is higher, the potential becomes positive, and when it is lower than the reference water level L _S , it becomes negative.

Therefore, the detection signal b output from the water level sensor 8 and transmitted by the transmitter 9 to the distant monitoring center via the signal path 10a is, as shown in FIG.
This is a continuous signal that continuously changes to the positive electrode side and the negative electrode side across the level line. The receiver 11 of the monitoring center receives the detection signal b and sends it to the display 12. The display 12 displays the water level L obtained from the detection signal b.

On the other hand, a pump on / off monitor 13 monitors the operating state of a pump provided in a water treatment plant, a water purification plant, or the like. Then, as shown in FIG. 10 (b), a discontinuous state signal having a positive constant value (E ₀ ) when the pump is in a start state and a negative constant value (−E ₀ ) when the pump is in a stop state. Output c.

The state signal c shown in FIG. 11C output from the pump on / off monitor 13 is transmitted by the transmitter 14 to the monitoring center via the signal path 10b. The receiver 15 of the monitoring center receives the status signal c and sends it to the display 12. The display 12 indicates the on / off state of the pump obtained from the state signal c.

[0009]

However, the telecommunication line shown in FIG. 8 and the remote monitoring system shown in FIG. 10 still have the following problems to be improved. In the telecommunication line shown in FIG. 8, the output voltages of the pair of DC power supplies 4a and 4b do not always match exactly. Further, the impedance 7 of the signal path 2 fluctuates greatly due to weather, load fluctuation, and other effects. As a result, the current signal a ′ flowing through the signal path 2 becomes 0 as shown by the broken line in FIG.
There is a concern that the waveform is not always symmetric with respect to the level line. As a result, there is a concern that the polarized relay 6 of the receiving terminal 3 may malfunction.

[0010] In the remote monitoring system shown in FIG.
Since the detection signal “b” transmitted to the distant monitoring center via “a” is an analog signal, the value of the current signal b ′ at the time when the signal is received by the receiver 11 according to the impedance state of the signal path 10 a naturally becomes There is a concern that it will fluctuate as shown by the broken line in FIG. Therefore, the accuracy of the water level L displayed on the display 12 decreases.

The current signal b 'corresponding to the state signal b output from the pump on / off monitor 13 is
Due to the mismatch between the output voltages of the pair of constant voltage sources housed in the on / off monitor 13 and the influence of the impedance of the signal path 10b, when the signal is input to the receiver 15, FIG.
As shown by the dotted line in (c), the waveform becomes an asymmetric waveform with respect to the 0 level line.

Further, in the remote monitoring system shown in FIG. 10, a detection signal b which is a continuous signal and a state signal c which is a discontinuous signal are respectively separated from signal paths 10a and 10b.
Therefore, it is necessary to perform transmission by using the communication, and the configuration of the entire system becomes complicated.

The present invention has been made in view of such circumstances, and utilizes a characteristic inherent in a constant current circuit to transfer information of a continuous signal and information of a discontinuous signal into one signal path. It is an object of the present invention to provide a bipolar current detection device capable of transmitting data accurately through the device.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a bipolar current detecting device according to a first aspect of the present invention comprises a continuous signal which changes continuously in both positive and negative polarities and a positive constant value or a negative constant value. A pair of input terminals into which a discontinuous signal that changes in value is input, and a current connected between the pair of input terminals, wherein a current proportional to the input current value is output when a current value of the input signal is equal to or less than a specified value; A pair of constant current circuits for controlling the output current value to a constant value when the signal current value exceeds a specified value, and each current is controlled such that the directions of the currents flowing into the respective constant current circuits are opposite to each other. A pair of rectifying elements, a reference resistor inserted in a current path for at least one of the pair of constant current circuits, and a current value flowing through the reference resistor by detecting a voltage between terminals of the reference resistor. Detect at least In Claim 2, each constant current circuit in the bipolar current detecting device according to Claim 1 is provided with a reference resistor and a MOS type FET inserted in series in a current path; It comprises a DC reference voltage source and an operational amplifier for applying a difference voltage between the output voltage of the DC reference voltage source and the voltage between the terminals of the reference resistor to the gate terminal of the MOSFET.

According to a third aspect of the present invention, a pair of constant current circuits in the bipolar current detecting device of the first aspect are connected in series between a pair of input terminals. Further, each constant current circuit is connected to a reference resistor and a MOS FET inserted in series in a current path, a DC reference voltage source, and a differential voltage between an output voltage of the DC reference voltage source and a voltage between terminals of the reference resistor. And an operational amplifier applied to the gate terminal of the type FET. Furthermore, each rectifying element is connected between the source and the drain of the MOSFET of each constant current circuit, and the current detection circuit is connected between both terminals of the reference resistor inserted in the current path of one of the constant current circuits. are doing.

According to a fourth aspect of the present invention, a pair of constant current circuits in the bipolar current detecting device of the first aspect are connected in parallel between a pair of inputs via a reference resistor. Further, each rectifying element is interposed between each constant current circuit and one input terminal. Further, the current detection circuit is connected between both terminals of the reference resistor inserted in the common current path of the pair of constant current circuits connected in parallel.

In the bipolar current detecting device configured as described above, a pair of constant current circuits are connected between a pair of input terminals. Then, by the pair of rectifying elements, the signal component on the positive side of the input signal is input to one constant current circuit, and the signal component on the negative side of the input signal is input to the other constant current circuit.

Generally, in a constant current circuit, when the current value of an input signal to the constant current circuit exceeds a specified value, the current value of the output signal is controlled to a predetermined constant value. In general, a current exceeding a specified value is applied to the constant current circuit.

Therefore, if the positive constant value or the negative constant value of the discontinuous signal is set so as to exceed the specified current value, when the discontinuous signal has a positive constant value, the positive side constant current circuit causes a pair of signals. A predetermined current in the positive direction flows between the input terminals. On the other hand, when the discontinuous signal has a constant negative value, the negative constant current circuit causes a predetermined negative current to flow between the pair of input terminals.

Each predetermined current flowing between the pair of input terminals in the positive or negative direction can be accurately determined by detecting the voltage across the reference resistor inserted in the current path. The obtained predetermined current values in the positive or negative direction may be A / D converted and transmitted, for example.

Therefore, it is possible to eliminate the influence of the mismatch between the output voltages of the pair of voltage sources that generate the positive constant voltage and the negative constant value. When the current value of the input signal to the constant current circuit is equal to or less than the specified value, the constant current circuit cannot output a current of a predetermined value, and outputs a current corresponding to the current value of the input signal.

Therefore, if the maximum current value of a continuous signal that continuously changes in both positive and negative polarities is limited to the specified value or less, the current value of the input signal is reduced through a constant current circuit between a pair of input terminals. A proportional current flows. The current value of the current flowing in the positive or negative direction between the pair of input terminals is obtained by detecting the voltage across the reference resistor inserted in the current path. The obtained current value may be subjected to, for example, A / D conversion and processing such as display.

Therefore, with this bipolar current detecting device, a continuous signal that changes continuously in both positive and negative polarities can be detected as an analog continuous value, and a positive constant value or a negative constant value can be detected. For a discontinuous signal that changes to
For example, it can be detected as a binary value of on or off.

According to a second aspect of the present invention, the constant current circuit comprises a reference resistor, a MOSFET, a DC reference voltage source, and an operational amplifier. Then, the reference resistor for current detection to which the current detector is connected is directly incorporated in a constant current circuit as a reference resistor used for setting a specified current value. Therefore, the number of expensive reference resistors can be reduced, and the circuit configuration can be simplified.

According to a third aspect of the present invention, each of the constant current circuits having the structure of the second aspect is connected in series between input terminals, and a rectifying element is connected between the source and the drain of the MOS type FET of each constant current circuit. I have. The current detector is connected to a reference resistor of one of the constant current circuits.

Since the reference resistor and the MOSFET are connected in series and the rectifier is connected in parallel to the MOSFET, a current flowing in either positive or negative direction flows through both reference resistors. Therefore, the current detector may be connected to only one of the reference resistors. As a result, the number of installed current detectors can be reduced to one.

According to a fourth aspect of the present invention, each of the constant current circuits is connected in parallel between the input terminals, and each of the rectifying elements is interposed between each of the constant current circuits and one of the input terminals. Another reference resistor is inserted in a common current path of the constant current circuit of the above, and a current detector is connected to this reference resistor. As a result, the number of current detectors can be reduced to one as in the third aspect.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a schematic configuration of a remote monitoring system in which the bipolar current detecting device of the first embodiment is incorporated.

The analog sensor 21 is, for example, as shown in FIG.
(A) outputting a continuous signal b ₂ analog continuously changes over the positive and negative polarities in the same manner as the water level sensor 8 shown in. The continuous signal b ₂ output from the analog sensor 21 is input to one terminal of the switch 23 after the gain is adjusted by the amplifier 22.

The on / off sensor 24 is, for example, as shown in FIG.
Similarly to the pump on / off monitor 13 shown in (b),
Positive constant value (E ₀₎ or a negative constant value and outputs a discontinuity signal c ₂ that changes (-E _0). The discontinuous signal c ₂ output from the on / off sensor 24 is input to the other terminal of the switch 23 after the gain is adjusted by the amplifier 25.

The switching unit 23 receives a continuous signal b from the analog sensor 21 based on a switching command input from the outside, for example.
₂ or a discontinuous signal c ₂ from the on / off sensor 24 is transmitted to a bipolar current detecting device 26 installed in the monitoring center via a signal path 27. In addition,
The signal path 27 has an impedance 27a that fluctuates greatly due to weather, load fluctuation, and other effects.

The bipolar current detecting device 26 reads the current value of the input continuous signal b ₂ or discontinuous signal c ₂ and
D-converted digital continuous signal b ₃ or discontinuous signal c ₃
To the display 30. Display 30 continuously displays the on-off state of the water level or pump is varied based on digital continuous signal b ₃ or discontinuous signals c _3.

FIG. 2 is a detailed circuit diagram of the bipolar current detector 26. A pair of input terminals 31 connected to the signal line 27
a, 31b, a diode 3 as a rectifying element having the illustrated polarity;
2a and a series circuit of the first constant current circuit 33a are connected. Further, a series circuit of a diode 32a having a polarity opposite to that of the diode 32a and a second constant current circuit 33b is connected in parallel with the series circuit.

In the first constant current circuit 33a, a reference resistor 34a having a resistance value R _S and an n-channel MOS FET 35a are connected in series between the input terminal 31b and the diode 32a. Reference resistor 34a and MOS FET
The potential at the connection point with 35a is applied to the inverting input terminal of the operational amplifier 36a. DC reference voltage source 37a for outputting the reference voltage V _S is between the non-inverting input terminal and the input terminal 31b of the operational amplifier 36a is connected.

In the second constant current circuit 33b, a reference resistor 34b having a resistance value R _S and a p-channel MOS type FET 35b are connected in series between the input terminal 31b and the diode 23b. Reference resistor 34b and MOS FET
The potential at the connection point with 35b is applied to the inverting input terminal of the operational amplifier 36b. DC reference voltage source 37b for outputting the reference voltage V _S is between the non-inverting input terminal and the input terminal 31b of the operational amplifier 36b is connected. Note that the DC reference voltage source 37b is inserted with a polarity opposite to that of the DC reference voltage source 37a of the first constant current circuit 33a.

Reference resistance 34a of first constant current circuit 33a
Current detector 3 comprising an A / D converter between both terminals of
8a is connected to the reference resistor 3 of the second constant current circuit 33b.
A second current detector 38b composed of an A / D converter is connected between both terminals of 4b. Each current detector 38a, 38
b denotes current values Ia, Ia flowing through the reference resistors 34a, 34b.
b is replaced with each of the reference resistors 34a. This is calculated by measuring the voltages Va and Vb across the terminal 34b.

Ia = Va / R _S Ib = Vb / R _S For example, the input terminal 31 a is a positive terminal and the input terminal 3
If 1b is a negative terminal, the positive side signal component of the continuous signal b ₂ or the discontinuous signal c ₂ flows through the first constant current circuit 33a due to the presence of the diode 32a, and the second constant current circuit 3
Negative signal component of the continuous signal b ₂ or discontinuous signals c ₂ to 3b flows.

Accordingly, the first current detector 38a indicates the positive current value Ia of each of the signals b ₂ and c _{2 by} , for example, 8 bits and sends it to the next synthesizing circuit 39. On the other hand, the second current detector 38b indicates the negative current value Ib of each of the signals b ₂ and c _{2 by} , for example, 8 bits and sends it to the next combining circuit 39.

The synthesizing circuit 39 synthesizes the positive current value Ia and the negative current value Ib, and generates a digital continuous signal composed of a total of 16 bits, ie, 8 bits on the positive side and 8 bits on the negative side, across both positive and negative polarities. b ₃ or the discontinuous signal c ₃ to the next display 3
Output to 0.

Next, the operation of the first constant current circuit 33a will be described with reference to the characteristic diagram of FIG. This first constant current circuit 3
Assuming that the current flowing through 3a is Ia, the current is controlled to a specified value _Is (predetermined value) substantially as described below.

I _S = V _S / R _{S When the} current Ia flowing through the constant current circuit 33a is extremely small, the current Ia does not increase to the specified current I _S but the current I proportional to the current Ia is increased. Flows.

FIG. 3 is a diagram showing the relationship between the input current Ia and the output current I of the constant current circuit 33a.

The second constant current circuit 33b has substantially the same configuration as the first constant current circuit 33a. In the remote monitoring system incorporating the bipolar current detecting device 26 configured as described above, the analog sensor 2 is
Continuous signals b ₂ of the signal current output from 1 are adjusted gain so as not to exceed the specified value I _S described above. The adjustment of the gain so greatly exceeds the prescribed value I _S for each current value corresponding to the positive constant value and a negative side predetermined value discrete signal c ₂ outputted from the on-Ofusensa 24 by the amplifier 25 described above are doing.

When the switch 23 is connected to the analog sensor 21, the continuous signal b ₂ input from the analog sensor 21 to the bipolar current detection device 26 via the signal path 27 indicates a positive value. , The first constant current circuit 33a
Current detector 38a connected to reference resistor 34a of
It is detected by. Further, continuous signal b ₂ from the analog sensor 21 if a negative value is detected by the second current detector 38b that is connected to the reference resistor 34b of the second constant current circuit 33b. Accordingly, the digital continuous signal b ₃ which continuously vary over the positive and negative polarities from the synthesis circuit 39 is output.

When the switch 23 is connected to the on / off sensor 24, if the discontinuous signal c ₂ input from the on / off sensor 24 to the bipolar current detector 26 has a positive value, value is controlled to prescribed current value I _S by the first constant current circuit 33a, it is detected by the first current detector 38a connected to the reference resistor 34a. In addition,
When the discontinuous signal c ₂ input from the off sensor 24 to the bipolar current detecting device 26 indicates a negative value, the negative value indicates the second value.
Of the control of the prescribed current value I _S by a constant current circuit 33b, it is detected by the second current detector 38b that is connected to the reference resistor 34b. Accordingly, the digital discrete signals c ₃ changing from the combining circuit 39 to the positive constant value and a negative side predetermined value is output.

[0046] Thus, since each current value corresponding to the positive values and negative values of the discrete signal c ₂ is controlled to be forcibly prescribed value I _S, even if discrete signal c ₂ positive value and negative value Is not always symmetrical with respect to the 0 level line, and even if the levels of the positive and negative values fluctuate due to the fluctuation of the impitance 27a in the signal path 27, the correct binarized ON state is always obtained.・ Off information can be obtained.

Further, with the bipolar current detecting device 26, a continuous signal b ₂ continuously changing in both positive and negative polarities.
For be detected as an analog continuous values, and with respect to the discontinuous signal c ₂ which changes a constant positive value or a negative constant value, it can be detected as a binary, for example on or off.

Accordingly, the number of signal paths can be reduced to one as compared with the conventional remote monitoring system shown in FIG. 10, and the number of transmitters and receivers not shown in FIG. Since the cost can be reduced, the equipment cost of the entire system can be reduced.

(Second Embodiment) FIG. 4 is a circuit diagram showing a bipolar current detecting device 26a according to a second embodiment of the present invention.
The same parts as those of the bipolar current detecting device 26 of the first embodiment shown in FIG. Therefore, the detailed description of the overlapping part will be omitted.

The bipolar current detecting device 2 of the second embodiment
In 6a, first and second constant current circuits 33a and 33b are connected in parallel to a pair of input terminals 31a and 31b via diodes 32a and 32b, respectively.
A common reference resistor 40 is interposed between one input terminal 31b of the pair of input terminals 31a and 31b and each of the constant current circuits 33a and 33b. This reference resistor 40 has the same resistance value _RS as each of the reference resistors 34a and 34b incorporated in each of the constant current circuits 33a and 33b.

A current detector 41 composed of an A / D converter is connected between both terminals of the common reference resistor 40. The current detector 41 detects the value of the current flowing through the reference resistor 40, including the flowing direction (positive or negative polarity).

In the bipolar current detecting device 26a thus configured, the first and second constant current circuits 33a, 33
3b and the diodes 32a and 32b have the same function and operation as the bipolar current detection device 26 of the first embodiment.
Therefore, the common reference resistor 40 has the input terminal 31a
Each successive signals b ₂ which side is positive electrode side, each successive signals b ₂ discontinuities signal c _2, and an input terminal 31b side is a positive electrode side, each current discontinuity signal c ₂ flows. However, the flowing directions are different.

The current flowing through the common reference resistor 40 is applied to the reference resistor 34 in the first and second constant current circuits 33a and 33b.
a, 34b are the same as the currents flowing individually.
Thus, with a single current detector 41 may be like the double polarity current detection device 26 of the first embodiment to obtain a digital continuous signal b ₃ and a discontinuous signal c _3.

Therefore, substantially the same effects as those of the bipolar current detecting device 26 of the first embodiment can be obtained, and
The required current detector 41 can be reduced to one, the circuit configuration can be simplified, and the manufacturing cost can be reduced.

(Third Embodiment) FIG. 5 is a circuit diagram showing a bipolar current detector 26b according to a third embodiment of the present invention.
The same parts as those of the bipolar current detecting device 26 of the first embodiment shown in FIG. Therefore, the detailed description of the overlapping part will be omitted.

The bipolar current detecting device 2 of the third embodiment
In 6b, first and second constant current circuits 42a and 42b are connected in series between a pair of input terminals 31a and 31b. Further, the first and second constant current circuits 42a, 42
Diodes 45a and 45b whose polarity is set so that the directions of currents flowing into 2b are opposite to each other are connected in parallel.

In the first and second constant current circuits 42a and 42b, the constant current circuits 32a and 32a of the first and second embodiments are used.
Instead of the MOS FETs 35a and 35b in 32b, npn transistors 43a and 43b are employed. Further, each of the transistors 43a, 43b
A backflow prevention diode 4
4a and 44b are connected.

The constant current circuits 42a and 42b using the transistors 43a and 43b have almost the same functions and operations as the constant current circuits 32a and 32b of the first embodiment.

In the bipolar current detecting device 26b thus configured, when the signal values of the continuous signal b ₂ and the discontinuous signal c ₂ input to the input terminals 31a and 31b are positive, the signal is input from the input terminal 31a. The current is supplied to the first constant current circuit 4
2a and the other input terminal 32 via the diode 45b.
to b. In the process of flowing through the first constant current circuit 42a, the current value is detected by the current detection circuit 38a as a positive current value.

On the other hand, when the signal values of the continuous signal b ₂ and the discontinuous signal c ₂ input to the input terminals 31a and 31b are negative,
The current input from the input terminal 31b is supplied to the other input terminal 3 via the second constant current circuit 42b and the diode 45a.
2a. In the process of flowing through the second constant current circuit 42b, the current value is detected by the current detection circuit 38b as a negative current value.

Therefore, similarly to the bipolar current detecting device 26 of the first embodiment, the digital continuous signal b ₃ and the discontinuous signal c ₃ are output from the synthesizing circuit 39. In this manner, a pair of constant current circuits 42a. 42b is connected in series, the pair of constant current inference circuits 32a and 32
It is possible to obtain substantially the same effects as those of the bipolar current detectors 26 and 26a of the first and second embodiments in which b is connected in parallel.

(Fourth Embodiment) FIG. 6 is a circuit diagram showing a bipolar current detector 26c according to a fourth embodiment of the present invention.
The same parts as those of the bipolar current detecting device 26b of the third embodiment shown in FIG. Therefore, the detailed description of the overlapping part will be omitted.

The bipolar current detecting device 2 of the fourth embodiment
In the first and second constant current circuits 46a and 46b connected in series between the pair of input terminals 31a and 31b in FIG. 6c, the first and second constant current circuits 42a and 42 shown in FIG.
Instead of the transistors 43a and 43b, n-channel MOS FETs 36a and 36b are used, and the backflow prevention diodes 44a and 44b are removed.

The bipolar current detecting device 26 having such a configuration is described.
In the case of c, substantially the same effect as that of the bipolar current detecting device 26c of the third embodiment shown in FIG. 5 can be obtained. (Fifth Embodiment) FIG. 7 is a circuit diagram showing a bipolar current detector 26d according to a fifth embodiment of the present invention. The same parts as those of the bipolar current detecting device 26c of the fourth embodiment shown in FIG. Therefore, the detailed description of the overlapping part will be omitted.

The bipolar current detecting device 2 of the fifth embodiment
6d, the first and second constant current circuits 46a and 46b are connected in series between the pair of input terminals 31a and 31b, and the MOS type FE in each of the constant current circuits 46a and 46b is connected.
Diodes 48a and 48b as rectifying elements are connected between the sources and drains of T36a and 36b with the polarities shown.

A current detector 49 composed of an A / D converter is connected between both terminals of the reference resistor 34a incorporated in one constant current circuit 46a. This current detector 4
9 is a current detector 41 according to the second embodiment shown in FIG.
And detects the value of the current flowing through the reference resistor 34a, including the direction in which the current flows (positive or negative polarity).

The bipolar current detecting device 26 having such a configuration is described.
In d, since the diodes 48a and 48b are connected between the sources and drains of the MOS FETs 36a and 36b, the reference signals 34a and 34b have continuous signals b ₂ , input to the input terminals 31a and 31b, respectively. even a discontinuous signal c ₂ had any polarity of the positive side and the negative electrode side, always current flows. However, the flowing directions are different. Therefore, with one current detector 49, the second
Similar to the double polarity current detector 26a embodiment can output a digital continuous signal b ₃ and a discontinuous signal c _3.

Therefore, in addition to obtaining substantially the same effect as the bipolar current detecting device 26c of the fourth embodiment shown in FIG. 6, the number of the current detectors 49 can be reduced to one, and the entire device can be reduced. The circuit configuration can be simplified and the manufacturing cost can be reduced.

In this embodiment, the parasitic diode included in the MOS FET itself has the function of the rectifying element, so that the diode 48 connected separately to the outside can be used.
a, 48b can be removed. in this case,
The circuit configuration is further simplified.

[0070]

As described above, the constant current circuit incorporated in the bipolar current detecting device of the present invention has a general function of controlling the input current to a predetermined current value, and a function of controlling the input current. If the current value is significantly smaller than the specified current value, the current value is output in proportion to the input current.

In the bipolar current detecting device of the present invention, when the input signal is a discontinuous signal that changes to a constant positive value or a constant negative value, the general former function is used, and the input signal is In the case of a continuous signal that changes continuously in both positive and negative polarities, the latter function is used. Therefore, the information of the continuous signal and the information of the discontinuous signal can be accurately transmitted through one signal path, so that the reliability of the system in which this device is incorporated can be improved and the configuration can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a remote monitoring system in which a bipolar current detection device according to a first embodiment of the present invention is incorporated.

FIG. 2 is a detailed circuit diagram of the bipolar current detection device of the first embodiment.

FIG. 3 is a diagram showing current control characteristics of each constant current circuit incorporated in the bipolar current detection device.

FIG. 4 is a detailed circuit diagram showing a bipolar current detection device according to a second embodiment of the present invention.

FIG. 5 is a detailed circuit diagram showing a bipolar current detection device according to a third embodiment of the present invention.

FIG. 6 is a detailed circuit diagram showing a bipolar current detection device according to a fourth embodiment of the present invention.

FIG. 7 is a detailed circuit diagram showing a bipolar current detection device according to a fifth embodiment of the present invention.

FIG. 8 is a schematic diagram showing a general telegraph line.

FIG. 9 is a waveform diagram of a telegraph signal transmitted through a signal path of the telegraph line.

FIG. 10 is a schematic diagram showing a general remote monitoring system.

FIG. 11 is an operational characteristic diagram of a water level sensor and a pump on / off monitor incorporated in the remote monitoring system.

[Explanation of symbols]

Reference Signs List 21 analog sensor 23 switch 24 on / off sensor 26, 26a, 26b, 26c, 26d bipolar current detector 31a, 31b input terminal 32a, 32b, 45a, 45b, 48a, 48b diode 33a, 42a , 46a ... first constant current circuits 33b, 42b, 46b ... second constant current circuits 34a, 34b, 40 ... reference resistors 35a, 35b, 47a, 47b ... MOS FETs 36a, 36b ... operational amplifiers 37a, 37b ... DC reference voltage source 38a, 38b, 41, 49 ... current detector

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Tadano 5-10-27 Minamiazabu, Minato-ku, Tokyo Inside Anritsu Corporation (72) Inventor Yoichi Maeda 3-2-1-2 Nishishinjuku, Shinjuku-ku, Tokyo Date Within the Telegraph and Telephone Corporation (72) Inventor Seiichi Yamano 3-192-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Within the Telegraph and Telephone Corporation (72) Inventor Masaru Tsuchiya 3-192, Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation (56) References JP-A-56-153497 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G08C 19/02 G01R 19/14 H04B 3 / 50 H04L 25/02

Claims (4)

(57) [Claims] 1. A pair of input terminals (31a, 31b) to which a continuous signal which continuously changes in both positive and negative polarities and a discontinuous signal which changes to a positive constant value or a negative constant value are inputted. Connected between a pair of input terminals, outputs a current proportional to the input current value when the current value of the input signal is equal to or less than a specified value,
A pair of constant current circuits (33a, 33b, 42a, 42) for controlling the output current value to a constant value when the current value of the input signal exceeds the specified value.
b, 46a, 46b) and a pair of rectifying elements (3, 4) for controlling the respective currents so that the directions of the respective currents flowing into the respective constant current circuits are opposite to each other.
2a, 32b, 45a, 45b, 48a, 48b), a reference resistor (34a, 34b, 40) inserted in a current path for at least one constant current circuit of the pair of constant current circuits, A bipolar current detection device comprising: at least one current detector (38a, 38b, 41, 49) for detecting a value of a current flowing through the reference resistor by detecting a voltage between terminals. 2. The constant current circuit according to claim 1, wherein the reference resistor and a MOS FET (35a, 35b, 47a, 4a) inserted in series in a current path.
7b), a DC reference voltage source (37a, 37b), and an operational amplifier (36a) for applying the difference voltage between the output voltage of the DC reference voltage source and the voltage between the terminals of the reference resistor to the gate terminal of the MOSFET. , 36b).
The bipolar current detection device according to the above. 3. The pair of constant current circuits (46a, 46b) are connected in series between the pair of input terminals, and each of the constant current circuits (46a, 46b) is connected to the reference current inserted in series in a current path. A resistor and a MOS FET (47a, 47b), a DC reference voltage source, and an operation for applying a difference voltage between an output voltage of the DC reference voltage source and a voltage between terminals of the reference resistor to a gate terminal of the MOS FET. And each rectifier element (48a, 48b) is a MOS of the respective constant current circuit.
The current detection circuit (49) is connected between the source and the drain of the type FET;
2. The bipolar current detecting device according to claim 1, wherein said bipolar current detecting device is connected between both terminals of a reference resistor (34a) inserted in the current path of (46a). 4. The pair of constant current circuits are connected in parallel between the pair of inputs via the reference resistor, and each of the rectifying elements is inserted between each of the constant current circuits and the one input terminal. The current detection circuit (41) is connected between both terminals of a reference resistor (40) inserted in a common current path of the pair of constant current circuits connected in parallel. The bipolar current detection device according to claim 1.