JPH04340417A - Non-powered remotely measuring optical apparatus - Google Patents

Abstract

PURPOSE:To enable easy measurement of physical change quantity without being affected by electromagnetic induction from thunder, a power line or the like by picking up a variation of the physical quantity measured with a sensor section by an FM measurement system through an optical cable. CONSTITUTION:A signal from a Wien bridge oscillation circuit 15 is converted into a light signal with an electro-photo-conversion circuit 18 o be transmitted to a sensor part 12. A variation corresponding to a change in the physical quantity measured at the sensor part 12 is added to the light signal. The light signal with the variation added thereto is sent out to a measuring part 11 through an optical cable 14 and after converted into an electrical signal with a conversion circuit 19, it is fed back to the circuit 15. The circuit 15, which is of a double feedback structure, has an oscillation frequency change according to a variation of the physical quantity measured at the sensor part 12 interposed in a path of an external feedback system. By such an FM type measuring system, a change in the oscillation frequency of the circuit 15 is picked up as measurement results of the change in the physical quantity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical power-free remote measuring device suitable for use, for example, in monitoring remote locations where it is difficult to use power supply facilities.

0002

2. Description of the Related Art As is well known, in hydroelectric power plants and the like, for example, measuring the amount of snowfall is one of the very important factors in formulating future power generation plans. Incidentally, since snowfall measurement points are often located in mountainous areas, it is often necessary to carry out remote measurement, and for this purpose, various snowfall remote measurement systems have been considered.

The following conditions are required for this type of snowfall remote measurement system: (1) It must be able to measure the weight of snowfall. (2) The sensor part must be without power. (3) Must be able to avoid electromagnetic interference caused by lightning, etc. Needless to say, it is necessary to be robust against changes in weather conditions such as wind and temperature, and to be able to perform accurate measurements even when snow melts or refreezes.

[0004] However, the conventional snowfall amount remote measurement system is still in the development stage, and at present no technology has been established that satisfies all of the above-mentioned conditions at a practical level. We are in a situation where we cannot say that we are doing well. Furthermore, even if we expand the scope to include general systems that remotely measure changes in physical quantities such as mass and temperature in addition to the amount of snow, the current situation is almost the same as above.

[0005]

[Problems to be Solved by the Invention] As described above, the technology of conventional systems for remotely measuring changes in physical quantities has not been established to a sufficiently practical level, and there is still room for improvement in various aspects. It is what is left.

Therefore, the present invention was made in consideration of the above-mentioned circumstances, and the sensor part does not require power supply equipment at the measurement point or electric energy transmission to the measurement point. Another object of the present invention is to provide an extremely good optical-applied powerless remote measuring device that can easily measure changes in physical quantities in remote locations without being affected by electromagnetic induction from power lines or the like.

[0007]

[Means for Solving the Problems] The optical application powerless remote measuring device according to the present invention is directed to a remote measuring system that measures changes in a physical quantity at a measuring point at a measuring location distant from the measuring point. A Wien bridge oscillation circuit having an internal feedback system for maintaining its own oscillation conditions, an electric/optical conversion means for generating an optical signal corresponding to the oscillation output of this Wien bridge oscillation circuit, and this electric/optical conversion a first optical cable that transmits the optical signal output from the means to the measurement point; a sensor part that is provided at the measurement point and gives a change in the amount of light corresponding to a change in the physical quantity to the optical signal transmitted by the first optical cable; A second optical cable transmits the optical signal, which is given a change in the amount of light corresponding to the change in the physical quantity at the sensor site, to the measurement location, and an electrical signal corresponding to the optical signal transmitted by this second optical cable is generated. Electrical/optical conversion for the Wien bridge oscillation circuit, comprising an optical/electrical conversion means and a multiplication means for multiplying the output of the optical/electrical conversion means by the output of the Wien bridge oscillation circuit and externally feeding the result to the Wien bridge oscillation circuit. The measurement result is a change in the oscillation frequency of the Wien bridge oscillation circuit caused by the characteristics of the external feedback system consisting of the means, the sensor part, the optical/electrical conversion means, and the multiplication means changing in accordance with changes in physical quantities. It is something.

[0008]

[Operation] According to the above configuration, the Wien bridge oscillator circuit has a double feedback structure and the sensor part is interposed in the path of the external feedback system, so that the Wien bridge oscillation circuit is configured to have a double feedback structure, and by interposing the sensor part in the path of the external feedback system, This is an FM measurement method in which the oscillation frequency of the Wien bridge oscillation circuit is changed, and the change in the oscillation frequency of the Wien bridge oscillation circuit is taken out as a measurement result of a change in a physical quantity. In this case, the signal transmission between the measurement location and the sensor site is performed by an optical signal using the first and second optical fiber cables, and the change in the physical quantity measured at the sensor site is determined by the amount of light of the optical signal. Since the sensor part does not require a power supply, there is no need for power supply equipment at the measurement point or electrical energy transmission to the measurement point, and it is not affected by electromagnetic induction from lightning, electric stations, power lines, etc. Changes in physical quantities at remote locations can be easily measured without being affected by

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. In FIG. 1, reference numeral 11 indicates a measurement site installed in a manned place, for example, and this measurement site 1
Sensor site 12 installed at a measurement point far away from 1
and are connected via optical fiber cables 13 and 14. This measurement site 11 has a Wien bridge oscillation circuit 15, the details of which will be described later. The sine wave signal output from this Wien bridge oscillation circuit 15 is
After being converted into a rectangular wave signal by a comparator 17 via an output terminal 16, it is converted into an optical signal by an E/O (electrical/optical) conversion circuit 18, and sent to the sensor site 12 via an optical fiber cable 13. .

A variable corresponding to a change in the physical quantity measured at the sensor site 12 is added to the optical signal supplied to the sensor site 12 via the optical fiber cable 13 . Specifically, the addition of this variable is as follows:
The amount of light of the optical signal supplied through the sensor part 12
This is done by increasing or decreasing in response to changes in physical quantities measured in . The optical signal to which this variable has been added is sent to the measurement site 11 via the optical fiber cable 14, first converted into an electrical signal by an O/E (optical/electrical) conversion circuit 19, and then converted to an electrical signal by a rectifier circuit 20. After being rectified, it is multiplied by the output sine wave signal of the Wien bridge oscillation circuit 15 obtained from the output terminal 16 in the multiplier circuit 21, and is fed back to the Wien bridge oscillation circuit 15 via the input terminal 22.

Here, the Wien bridge oscillation circuit 1
5 is configured as shown in FIG. That is, the input terminal 22 is connected to the operational amplifier OP1 via the resistor R1.
Connected to the positive input terminal + of The output terminal of the operational amplifier OP1 is connected to the output terminal 16 and also to the negative input terminal of the operational amplifier OP1 via the thermistor T, and the connection point is grounded via the resistor R2. . Furthermore, the output terminal of the operational amplifier OP1 is connected to the capacitor C1.
and a resistor R3 in series to the positive input terminal + of the operational amplifier OP1, and the connection point thereof is grounded through a resistor R4 and a capacitor C2 in parallel.

In this Wien bridge oscillation circuit 15, resistors R3, R4 and capacitors C1, C2 serve as an internal feedback system 23 for maintaining the original oscillation frequency, and the connection between the output terminal 16 and the input terminal 22 is A comparator 17, an E/O conversion circuit 18, a sensor part 12, an O/E conversion circuit 19, a rectifier circuit 20, a multiplication circuit 21, etc., connected between the is added to the external feedback system 24 whose feedback characteristics are modulated, and the internal feedback system 2 is
It has a double feedback structure of 3 and an external feedback system 24, and has the property of performing highly accurate FM modulation while stabilizing oscillation. Note that, in order to stabilize oscillation, the external feedback system 24 is sufficiently weaker than the internal feedback system 23, that is, is coupled to the operational amplifier OP1 with high impedance.

That is, according to the above embodiment, the Wien bridge oscillation circuit 15 has a double feedback structure, and the external feedback system 2
By interposing the sensor part 12 in the path of 4,
This is an FM measurement method in which the oscillation frequency of the Wien bridge oscillation circuit 15 is changed according to the amount of change in the physical quantity measured by the sensor part 12, and the change in the oscillation frequency of the Wien bridge oscillation circuit 15 is used as a change in the physical quantity. It is taken out as a measurement result.

In this case, the measurement site 11 and the sensor site 12
Signal transmission between the two is performed using optical fiber cables 13 and 14 as an optical signal, and a change in the physical quantity measured at the sensor part 12 results in an increase or decrease in the amount of light of the optical signal. It does not require a power source and does not require power supply equipment at the measurement point or electrical energy transmission to the measurement point, and can detect changes in physical quantities at remote locations without being affected by lightning, electromagnetic induction from electric stations, power lines, etc. Can be easily measured.

FIG. 3 shows an application example in which the above-described embodiment is utilized for remote measurement of snowfall amount. To explain by assigning the same reference numerals to the same parts as in FIG. /
An E conversion circuit 19, a rectifier circuit 20, a multiplication circuit 21, an input terminal 22, and the like are provided. And this manned place 25
and an unmanned place 26 corresponding to the sensor part 12 are connected by optical fiber cables 13 and 14.

Here, in the unmanned place 26 , the optical signal transmitted by the optical fiber cable 13 is converted into a parallel light beam by the microlens 27 integrated with the optical fiber cable 13 , and is integrated with the optical fiber cable 14 . An optical path for receiving the light is formed in the microlens 28 for receiving the light. And these micro lenses 27
, 28, a substantially cylindrical drum 29 is interposed. This drum 29 has its peripheral surface covered with a microlens 2
The microlenses 2 and 28 are supported rotatably around a central axis 29a so as to face the microlenses 2 and 28.
An optical transmission path 29b is formed to guide the light emitted from the microlens 7 to the microlens 28.

Further, one end portion of a substantially rod-shaped connecting member 30 is fixed to the central shaft 29a of the drum 29. Further, the other end of the connecting member 30 is rotatably connected to the receiving member 31 via a shaft 31a. This receiving member 31 is normally biased upward in the figure by a spring 32, and receives the weight of the snow 33, and the spring 32
It is pushed down in the figure against the urging force of 1. Then, as the receiving member 31 is pushed down in the figure by the weight of the snow 33, the drum 29 is rotated in the direction of the arrow shown in the figure, and the inclination of the optical transmission path 29b of the drum 29 changes. The amount of transmitted light transmitted to the microlens 28 is changed, that is, the feedback characteristic of the external feedback system 24 is modulated.

FIG. 4 shows the relationship between the load actually measured with the configuration shown in FIG. 3 and the oscillation frequency of the Wien bridge oscillation circuit 15. However, the oscillation frequency is not directly displayed, and the oscillation frequency of the Wien bridge oscillation circuit 15 when the external feedback system 24 is not connected is fo, and the oscillation frequency of the Wien bridge oscillation circuit 15 when the external feedback system 24 is connected is
The oscillation frequency of is set as f, and the ratio (f/fo) is shown. From the measurement results shown in Figure 4, approximately 2 to 12k
It was confirmed that the oscillation frequency changes linearly with respect to the load within the range of g. It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without departing from the gist thereof.

[0019]

[Effects of the Invention] As detailed above, according to the present invention,
The sensor part does not require power supply equipment at the measurement point or electrical energy transmission to the measurement point, and is not affected by electromagnetic induction from lightning, electric stations, power lines, etc.
It is possible to provide an extremely good optical application powerless remote measuring device that can easily measure changes in physical quantities in remote locations.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block circuit configuration diagram showing a detailed configuration of main parts of the embodiment.

FIG. 3 is a block configuration diagram showing an example in which the embodiment is applied to measurement of snowfall amount.

FIG. 4 is a diagram showing the measurement results of the snowfall amount.

[Explanation of symbols]

11...Measurement site, 12...Sensor site, 13, 14...Optical fiber cable, 15...Wien bridge oscillation circuit, 1
6... Output terminal, 17... Comparator, 18... E/O conversion circuit, 19... O/E conversion circuit, 20... Rectifier circuit, 21...
Multiplier circuit, 22... Input terminal, 23... Internal feedback system, 24...
External return system, 25...Manned place, 26...Unmanned place, 27, 28
... Microlens, 29 ... Drum, 30 ... Connection member, 3
1...Receiving member, 32...Spring, 33...Snow.

Claims (3)

[Claims] 1. A remote measurement system that measures changes in a physical quantity at a measurement point at a measurement location distant from the measurement point, comprising: a Wien bridge oscillation circuit having an internal feedback system for maintaining its own oscillation conditions; electrical/optical conversion means for generating an optical signal corresponding to the oscillation output of the bridge oscillation circuit; a first optical cable for transmitting the optical signal output from the electrical/optical conversion means to the measurement point; a sensor part that is provided and gives a change in the amount of light corresponding to the change in the physical quantity to the optical signal transmitted by the first optical cable; and an optical signal to which the sensor part gives a change in the amount of light corresponding to the change in the physical quantity. a second optical cable for transmitting the optical signal to the measurement location; an optical/electrical conversion means for generating an electrical signal corresponding to the optical signal transmitted by the second optical cable; a multiplication means for multiplying the output of the bridge oscillation circuit and externally feeding the result to the Wien bridge oscillation circuit; The optical application non-power source is characterized in that it is configured such that a change in the oscillation frequency of the Wien bridge oscillation circuit caused by the characteristics of the external feedback system changing in accordance with a change in the physical quantity is used as a measurement result. Telemetry device. 2. The optical application powerless remote measuring device according to claim 1, wherein the physical quantity is snow weight. 3. The sensor portion includes a member that moves up and down depending on the weight of snow, and a member that moves up and down in accordance with the weight of snow, and a
3. The optical power-free remote measuring device according to claim 2, further comprising a control means for controlling the transmission amount of optical signals from the optical cable to the second cable.