JP2589356B2 - Optical salt adhesion sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sensor for optically detecting the amount of salt attached.

[Prior Art] Conventionally, there are the following techniques for detecting the amount of salt.

The first is analysis by resistance measurement, in which the resistance of a solution containing NaCl is measured, and the amount of salt is determined from a conversion table. The second is optical analysis such as X-ray analysis, in which a solid sample containing NaCl is irradiated with X-rays, and the intensity of a diffraction line from a surface of a crystal of one component is measured and quantified. Things. Third, the refractometer method is used to quantify the content of each component in a mixed solution of NaCl and KCl by measuring the refractive index with a refractometer.

[Problems to be Solved by the Invention] However, the above-described conventional technology has the following problems.

(1) Various types of measuring equipment must be prepared.

(2) No change over time in the amount of salt can be detected.

(3) Real-time detection is not possible.

(4) Skill is required for the measurement, and it takes time and effort.

(5) It is difficult to measure in a vicious cycle under a high voltage or a high magnetic field, or in a dangerous environment.

(6) The measurement system becomes large and expensive.

(7) In the refractometer method, measurement can be performed only with a solution whose refractive index changes depending on the concentration of the contained solution.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide an optical salt adhesion amount detection sensor having a simple structure and excellent responsiveness.

[Means for Solving the Problems] An optical salt deposition detection sensor according to the present invention comprises a first optical waveguide having a refractive index smaller than that of NaCl, and a refractive index larger than that of NaCl. A second optical waveguide having a value is arranged in an array, and salt adhesion is determined from the difference between the amount of change in optical loss in the first optical waveguide and the amount of change in optical loss in the second optical waveguide. It is configured to be specified.

It is preferable that the first optical waveguide and the second optical waveguide are exposed and mounted on a thin film, and the amount of salt attached is determined from a change in transmitted light intensity.

[Operation] When light enters the first and second optical waveguides from one end thereof, the propagation light reaches the other ends of the first and second optical waveguides with almost no loss because the surroundings of both the waveguides are air. . But,
When salt particles adhere to the surface of the optical waveguide, light loss occurs in the first optical waveguide having a refractive index smaller than that of sodium chloride NaCl, but light loss occurs in the second optical waveguide having a refractive index larger than NaCl. No loss occurs. Therefore, by knowing the difference between the amount of change in light loss of the first optical waveguide and the amount of change in light loss of the second optical waveguide, it is possible to determine whether or not salt is attached. In this case, since the optical waveguides are arranged in an array, the attached amount of NaCl can be detected with high sensitivity over a wide range.

Next, under a configuration in which the first optical waveguide and the second optical waveguide are mounted while being exposed on the thin film, the sensor section is planar and flexible. For this reason, even if a place to be measured by providing the sensor section is a place having a curve or unevenness, for example, an insulator in a power transmission facility, it is not necessary to change the shape by processing or the like, and the sensor section can be used as it is. Can be attached. Therefore, the mountability is improved. Further, since the change in transmitted light intensity corresponds to the change in light loss, the amount of attached salt can be easily obtained from the change in transmitted light intensity.

As the thin film of the salt detection sensor unit, a flexible material such as a plastic film is preferable, and as a mounting means of two types of optical waveguides having different refractive index values with respect to the thin film,
There is an adhesive such as silicone resin. However, the silicone resin used between the thin film and the optical waveguide must have a refractive index smaller than that of the optical waveguide.

It is desirable that both ends of the optical waveguide be mounted as a bundle of silicone resin having a low refractive index value.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 shows a configuration diagram of the entire sensor. The sensor includes a light source 8, a sensor unit 12, light receivers 9 and 10, and a calculator 11. The sensor unit 12 includes a first optical waveguide 1 and a second optical waveguide 2, and light from the light source 8 is incident on the sensor unit 12 from one end of the optical waveguides 1 and 2. The light transmitted through the sensor unit 12 exits from the other ends of the optical waveguides 1 and 2, and is
Received at 9,10. The transmitted light intensities detected by the two light receivers 9 and 10 are input to the arithmetic unit 11 through the connection cable 13 and subjected to arithmetic processing.

More specifically, as can be seen from FIGS. 2 and 3, the sensor unit 12 includes two types of optical waveguides 1 and 2 having different refractive indexes.
On the surface of the thin film 3 made of plastic or the like, it has a structure in which it is arranged alternately in one direction in an array. The reason why the waveguides 1 and 2 are arranged in an array is to enable high sensitivity detection of the amount of sodium chloride NaCl deposited over a wide range. This is to allow the device to be easily mounted even when the surface to be measured on which the device is to be mounted is not flat. Optical waveguides used 1, 2
Is made of quartz glass (optical fiber) having a diameter of about 80 μm. Refractive index value of the optical waveguide 1 can be controlled by the addition of the impurity, the refractive index value of NaCl and (n _NaCl) those from the smaller refractive index value (n _A), greater than the refractive index value of NaCl (n _NaCl) Refractive index value (n _B ). Between the optical waveguides 1 and 2 and the thin film 3 and between the optical waveguides 1 and 2, a low refractive index value (n
_(A value smaller than _A ).

As shown in FIG. 2, the terminals of the optical waveguides 1 and 2 are
On the side, they are collected as a group of optical waveguides 5 without distinction between the optical waveguides 1 and 2, and on the side of the light receivers 9 and 10,
The optical waveguides 1 and the optical waveguides 2 having the same refractive index value are collected separately to form a bundle type structure. By using the bundle of optical waveguide bundles, the light source 1 can be a single common light source, and the number of light receivers 9, 10 can be a minimum of two.

As shown in FIG. 4, light is collected by a rod lens or the like between the bundle of optical waveguides 5 and the light source 8 and between the bundle of optical waveguides 1 and 2 and the light receivers 9 and 10. It is coupled via a lens 6. The bundle bundle, the optical fiber 7, the condenser lens 6, and the like are protected and fixed by a ceramic fixing jig 14.

Next, the operation of detecting the amount of salt attached to the sensor will be described.

To detect the amount of attached salt, light of the same wavelength is incident on the sensor unit 12 from the light source 8 and the intensity of each emitted light is measured by a separate light receiver.
The detection is performed at 9 and 10, and each signal change is led to the arithmetic unit 11 via the connection cable 13 and compared therewith.

More specifically, the refractive index values of the optical waveguides 1 and 2 in the sensor unit 12 are defined as n _A and n _B , respectively, where n _A and n _B are smaller than the refractive index value n _NaCl of the salt particles (NaCl). Large value (n _A
<N _NaCl <n _B ). By setting in this way, the amount of NaCl attached can be detected by the method described below. First, light emitted from the light source 8 reaches the sensor unit 12.
At this time, if there is no extraneous matter on the sensor unit 12, there is no light loss because the area around the sensor unit 12 is air. In addition, even if there is an attached matter, the refractive index value is the refractive index value of the optical waveguide 1.
When than n _A is a small one, most optical loss does not occur.

However, when the deposit is NaCl, the optical waveguide 1 causes a light loss and the optical waveguide 2 hardly causes a light loss.

Moreover, deposits, when those of the large refractive index value than the refractive index value n _B of the optical waveguide 2 are both of the optical waveguide 1 and 2 both, resulting in optical loss.

Above, summary, optical loss of the optical waveguide 1 to L _A, when the L _B was an optical loss of the optical waveguide _{2, (1) L A>} 0, L B> 0, (2) L A = L B ≒ 0, (3) There are three cases of L _A > 0 and L _B ≒ 0.

When (1) L _A > 0, L _B > 0 and (2) L _A = L _B ≒ 0, the deposit is other than NaCl, and (3) L _A > 0 , L _B ≒ 0, the deposit is NaCl
Can be determined.

Further, (3) when L _A > 0, L _B ≒ 0, L _{A at} that time
The value of indicates the amount of NaCl attached.

The value of the optical loss L _A, as shown below, the transmitted light intensity P _A detected by the photodetector 9, using P _B, obtained from the transmitted light intensity ratio P _A / P _B. Therefore, the arithmetic unit 11 of FIG. 1, the photodetector 9 and 10 at the detected transmitted light intensity P _A, compared by the comparator with P _B, the difference in transmitted light intensity P _A and P _B is set threshold If it is larger, it is determined as NaCl. Comparison result is NaCl
When NaCl determination signal indicating that it is obtained, executes the calculation for obtaining the ratio of the transmitted light intensity P _A and P _B, and calculates the deposition amount. Therefore, detection in real time is possible.

When the difference between the transmitted light intensity P _A and P _B as described above becomes a certain level or higher, by performing a calculation for obtaining the ratio of the transmitted light intensity P _A and P _B, with respect to the detection of salinity, the light source The effects of fluctuation can be eliminated. Further, by a method of calculating the ratio of the light intensity values obtained from the two light receivers 9 and 10, it is possible to eliminate influences other than those to be measured.

Since the sensor unit 12 is made of an insulator, it has excellent resistance to electromagnetic induction.

Although the preferred embodiment has been described above, the present invention is not limited to this, and can be changed or modified within the spirit of the present invention.

For example, as shown in FIG.
In addition, the sensor unit 12 and the light receivers 9 and 10 may be connected to each other via the optical fiber 7 so as to obtain the salt deposition information of the sensor unit 12 at a remote place.

Further, in the above embodiment, the salt was used as an example of the detection target, but by using an optical waveguide that matches the refractive index of the detection target, not only NaCl but also other attached substances can be detected.

[Effects of the Invention] The present invention is configured as described above, and has the following effects.

Salt adhesion can be easily discriminated by an optical method that uses two types of optical waveguides having a refractive index value smaller than the refractive index value of NaCl and a refractive index value larger than that of NaCl and knowing the difference in the amount of change in light loss between the two. . Moreover, since the optical waveguides are arranged in an array, the amount of attached NaCl can be detected with high sensitivity over a wide range. In addition, since the sensor section can be formed of an insulator, the sensor section is excellent in resistance to electromagnetic induction.

The optical waveguide is exposed and mounted on the thin film and the sensor section is made flexible, so that the optical waveguide can be easily installed on insulators of power transmission equipment regardless of the shape of the surface to be measured.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the sensor of the present invention, and FIG.
FIG. 3 and FIG. 3 are a plan view and a sectional view showing the structure of the sensor unit, FIG. 4 is a sectional view of a part connecting the sensor unit to an optical fiber, and FIG. 5 shows a modified embodiment of the sensor of the present invention. FIG. In the figure, 1 is an optical waveguide, 2 is an optical waveguide, 3 is a thin film, 4 is an adhesive, 5 is an optical waveguide group, 6 is a condenser lens, 7 is an optical fiber, 8 is a light source, 9 is a light receiver, and 10 is an optical fiber. Receiver, 11 is a computing unit,
Reference numeral 12 denotes a sensor unit, 13 denotes a connection cable, and 14 denotes a fixing jig.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Kawakami 3-13-3-4 Hidaka-cho, Hitachi City, Ibaraki Prefecture D-4 Terrace (72) Inventor Teruaki Tsutsui 3679 Ogizu-cho, Hitachi City, Hitachi City, Ibaraki Prefecture Isodai AP-E-101 (72) Inventor Yasuhiro Miyata 3923 Minamigaoka dormitory, 3923 Ogizu-cho, Hitachi City, Ibaraki Prefecture (56) References JP-A-61-145435 (JP, A) JP-A-1-147344 (JP, A)

Claims (2)

(57) [Claims] A first optical waveguide having a refractive index smaller than the refractive index of NaCl and a second optical waveguide having a refractive index larger than the refractive index of NaCl are arranged in an array. An optical salt adhesion amount detection sensor characterized in that the adhesion of salt is specified from the difference between the amount of change in the optical loss in the first optical waveguide and the amount of change in the optical loss in the second optical waveguide. 2. The light according to claim 1, wherein said first optical waveguide and said second optical waveguide are mounted on a thin film so as to be exposed, and the amount of salt attached is determined from a change in transmitted light intensity. Type salt amount detection sensor.