JP2001051068A - Freezing detection sensor and its sensor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accurate, relatively inexpensive freezing detection sensor using a sensor element by a triangular prism. SOLUTION: The freezing detection sensor is composed of a plurality of sensor elements 3 where a light incidence part formed on one surface of a triangular prism is connected to light-emitting equipment 5, a light emission part formed on the other surface is connected to a discriminator 6, and the remaining one surface is set to a liquid-contact surface, and a rod-shaped retaining body 2, where the sensor elements 3 are provided at an equal interval in the retaining body 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a freezing detection sensor for detecting the thickness of icing in seas and lakes, the freezing of water and road surfaces, or the icing condition of various devices and structures, and a sensor element thereof. It is about.

[0002]

2. Description of the Related Art In order to know the thickness of frozen ice in seas and lakes,
Holes are drilled in the ice floe with an auger, and measurements are taken with a ruler, or ice fragments from observation boats and icebreakers are visually measured. These are simple measurements but require manual labor. In particular, the former actual measurement is relatively accurate, but it is troublesome and dangerous. Therefore, install an ultrasonic transmitter and receiver on the sea floor or on the sea,
An ice thickness is determined by measuring a difference in reflection time of ultrasonic waves from a boundary between ice, air, and water. Further, a thermistor cable is stretched vertically, a temperature distribution at regular intervals is observed, and an ice thickness is obtained from a difference in temperature between ice, air, and water. However, these methods have problems such as a large-scale device and poor accuracy. Further, the detection of freezing of the water surface or the road surface is performed by visual observation or temperature measurement, but it is in a state where sufficient accuracy cannot be obtained without resorting to manual labor. Furthermore, icing on the device or structure has a significant effect on the performance of the device and the safety of the structure, but it has to rely on visual observation, it is troublesome, and the detection accuracy is poor.

By the way, an equilateral triangular prism is inserted between the optical fiber connecting the light emitter and the discriminator, the reflection coefficient (reflected light intensity) at the interface between the prism and the detection liquid is measured, and the refraction obtained from the reflection coefficient is measured. A detection sensor for discriminating a liquid from the rate has been proposed. As shown in FIG. 11, the detection sensor includes rod lenses 21 on two surfaces of an equilateral triangular prism 20.
22 and one rod lens 21 is connected to an optical fiber 23.
, The other rod lens 22 is connected to a discriminator 26 via an optical fiber 25, and the other surface of the regular triangular prism 20 is a liquid contact surface 27. And
The light emitted from the light emitter 24 is guided to the rod lens 21 by the optical fiber 23, becomes parallel light by the rod lens 21, and enters the equilateral triangular prism 20. The light reflected by the liquid contact surface 27 is converged by the rod lens 22 and
Is input to the discriminator 26 via the. The discriminator 26 measures the reflection coefficient, calculates the refractive index from the reflection coefficient, and determines and displays the liquid based on the refractive index.
However, this freezing detection sensor has only one regular triangular prism 20 as a sensor element, and cannot detect the thickness or width of ice formation, or the flat frozen state of a road surface or a water surface.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned problems in the prior art, and uses a triangular sensor element having a triangular prism to provide a highly accurate and relatively inexpensive sensor element. It is intended to provide a freezing detection sensor.

[0005]

According to the present invention, there is provided a freeze detecting sensor element comprising a triangular prism having a predetermined included angle combined with a rod lens and an optical fiber, wherein a surface of the triangular prism facing the included angle is a liquid contact surface, The other two surfaces are a light incident portion connected to a light emitting device and a light emitting portion connected to a discriminator, respectively, and a rod lens is attached so that incident and reflection angles can be adjusted via washers, and an optical fiber is connected. . The predetermined included angle of the triangular prism is preferably 52 to 62 degrees, and therefore, may be an equilateral triangular prism. In order to improve the accuracy, two pairs of light incident and light exit rod lenses attached to the prism may be provided, and the incident angles may be different from each other.

A freezing detection sensor for measuring the thickness of ice inserted into a frozen water surface is provided with a rod-shaped holder inserted into the frozen water surface, and the freezing detection sensor elements are mounted on the holding member at regular intervals. Are provided. Further, a freezing detection sensor for detecting the presence or absence of freezing by being inserted into a frozen water surface, a road surface, or the like, has a flat holding body inserted into the freezing surface, and the freezing detection sensor element is provided on the holding body. A plurality are provided in a shape. And a freeze detection sensor for detecting icing of a detection part exposed to the air such as various devices and structures is provided with a holder having an engagement means for engaging the detection part, The holder is provided with a plurality of the freeze detection sensors.

[0007] Since the reflection coefficient of air or soil is different from that of ice and water, which sensor element of the holder is ice or water.
You can know whether it is located in water, air or earth and sand. Therefore, it is possible to detect ice thickness, freezing, or icing. If the interval at which the sensor elements are mounted is reduced, the accuracy is improved. In the case of a icing sensor on a water surface or a road surface, a hole for insertion may be formed at the time of inspection for installing the holding body, or may be buried in advance, for example, in a side edge of a road. In the detection of icing, a freezing detection sensor is previously attached to a site where icing has a significant effect, and the attaching means may be a band or a bolt.

[0008]

Principle of the Invention For better understanding of the present invention, the power reflection coefficient which is the principle of the present invention will be described first. The reflection coefficient of light at the interface between two types of transparent objects having different refractive indexes changes depending on the incident angle of light, the state of polarization, and both refractive indexes. As shown in FIG. 1, the power reflection coefficient of reflected light when light is incident at an angle θ with respect to the normal L1 of the interface is expressed by the following equation.

Equation 1 In this equation, Rs and Rp are power reflection coefficients for s-polarized light (electric field is parallel to the interface) and p-polarized light (magnetic field is parallel to the interface), respectively. Also, the above equation is only valid when the square root in the equation is an incident angle having a positive value, and in other cases, it is total reflection and the power reflection coefficient is 1.0. This phenomenon occurs only when the refractive index eta ₁ of the incident angle is larger than the refractive index eta ₂ of the permeate side. Then a critical angle

Equation 2 Is present, and when the incident angle θ is larger than θc, total reflection occurs. Assuming that the refractive index of the prism is η ₁ and the incident angle of light on the bottom surface of the prism is η ₂ , the reflection coefficient is obtained from Expressions 1 and 2, and the refractive index of the liquid can be known from the measured value of the reflection coefficient. it can. The refractive index of water thus obtained is 1.333, and the refractive index of ice is 1.311. Since ice is a uniaxial crystal and has a different refractive index depending on the polarization state, an average value of both is taken. In the case of an acrylic resin, the refractive index of the prism was set to 1.475 by back calculation from the measured value of the total reflection angle with water of 64.67 degrees. FIG. 2 shows the change in the power reflection coefficient with respect to the refractive indexes of ice and water thus obtained. By judging the power reflection coefficient as can be understood from FIG. 2, it is possible to know which sensor element faces water and which sensor element faces ice. In the case of air or earth and sand, it can be similarly determined.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a freezing detection sensor for measuring the thickness of ice according to the present invention will be described. FIG.
In the freezing detection sensor 1 shown in FIG. 1, a plurality of sensor elements 3 are attached to a rod-shaped holder 2 at equal intervals, for example, at intervals of 5 cm. Each sensor element 3 has a box 4 attached to the upper end of the holder 2. The light emitting device 5 and the discriminator 6 are connected by optical fibers 7 and 8, respectively. In the example shown in the figure, a float 9 is provided on the upper part of the holding body 2 so that the float 9 is floated on the water surface before freezing, and the thickness 10 of the freezing is detected after freezing.

As shown in FIG. 4, the triangular prism 3a of the sensor element 3 is fixed to a hole 2a formed in the holder 2 by a block 3b, and light enters the triangular prism 3a at a predetermined included angle of 52 to 62 degrees. Rod lenses 3c and 3d are fixed to the two surfaces of the light emitting portion and the light emitting portion by a sleeve 3e, one rod lens 3c is connected to the light emitting device 5 via the optical fiber 7, and the other rod lens 3d is connected to the optical fiber 8. Is connected to the discriminator 6 via The surface exposed from the hole 2a is the liquid contact surface 3f.

As can be understood from the power reflection coefficient described above, the incident angle of light on the liquid contact surface 3f of the triangular prism 3a of the sensor element 3 for determining ice is 62 to 63 degrees. Therefore, the difference between the angle of the inclined surface of the triangular prism 3a and the angle of the inclined surface is adjusted by inserting a washer 3g between the rod lenses 3c and 3d and the prism inclined surface. A pair of rod lenses 3
When using the optical fibers c and 3d and the optical fibers 7 and 8, the incident angle is set to around 62.6 degrees. When two pairs of rod lenses 3c and 3d and optical fibers 7 and 8 are used, the accuracy is improved by setting the incident angles near 62 and 63 degrees, respectively.

As shown in FIG. 5, the light emitting device 5 provided in the box 4 includes a power supply 5a, a modulation circuit 5b connected to the power supply 5a and outputting a pulse signal for light emission, and a modulation circuit 5b. It is composed of a switching circuit 5c that switches sequentially in synchronization and light-emitting diodes 5d, 5d,... That emit light by pulse signals from the modulation circuit 5b transmitted through the switching circuit 5c. As the light emitting diode 5d, a near infrared semiconductor laser is used, and light emitted by a pulse signal from the modulation circuit 5b is transmitted to the sensor element 3 via the optical fiber 7.

Discriminator 6 provided in box 4
Is a photodiode 6a for detecting light from the sensor element 3 input via the optical fiber 8, an amplification circuit 6b for amplifying the output of the photodiode 6a, and a modulation circuit 5b.
A threshold discriminating circuit 6c which operates in synchronism with the above and receives the signal of the amplifier circuit 6b to discriminate ice;
The number of sensor elements 3 determined to be ice by
And a display 6e for displaying the ice thickness calculated by the arithmetic circuit 6d.

The freeze detection sensor 1 configured as described above
Is used by being floated on the water surface by a float 9 as shown in FIG. The pulse signal from the modulation circuit 5b of the light emitting device 5 provided in the box 4 is switched by the switching circuit 5c and sequentially output to the light emitting diodes 5d, 5d,.
Are sequentially sent to the sensor element 3 via the optical fiber 7.

In the sensor element 3, light input through the optical fiber 7 is converted into parallel rays by the rod lens 3c and is incident on the triangular prism 3a, and light reflected by the liquid contact surface 3f is collected by the rod lens 3d. Through the optical fiber 8 to the discriminator 6.

In the discriminator 6, the light input through the optical fiber 8 is detected by the photodiode 6a, and the output of the photodiode 6a is amplified by the amplifier circuit 6b and transmitted to the threshold value discriminating circuit 6c. Then, the threshold value discriminating circuit 6c operating in synchronization with the modulation circuit 5b discriminates ice from the signal received from the amplifying circuit 6b and transmits it to the arithmetic circuit 6d.

Thus, the light emitting diodes 5d, 5d
.. Sequentially emit light, and reflected light from the sensor elements 3, 3,. Then, the arithmetic circuit 6d of the discriminator 6 calculates the ice thickness 10 based on the number of sensor elements 3 determined to be ice by the threshold value discriminating circuit 6c and the interval between the sensor elements 3.
Is calculated, and the ice thickness 10 is displayed on the display 6e.

The arithmetic circuit 6d and the display 6e may transmit radio signals. In addition, when detecting the thickness of ice at a shallow place, the float 9 may not be provided at the upper end of the holder 2 and the lower end of the holder 2 may be driven into the ground like a pile.

Next, a description will be given of a freezing detection sensor for measuring the size of an ice surface according to another embodiment of the present invention. As shown in FIG. 6, the freezing detection sensors 11 are arranged at equal intervals, for example, 5c.
A plurality of sensor elements 13 are mounted at equal intervals, for example, at 5 cm intervals, on a planar holding body 12 assembled in a grid shape with m intervals, and each sensor element 13 is a light emitting device 1 in a box 14.
5 and the discriminator 16 via optical fibers 17 and 18. Then, the freezing detection sensor 11 floats on the water surface to detect the size of the freezing. In addition, the sensor element 13 and the light emitting device 1
5 and the configuration and operation of the discriminator 16 are the same as those described above, and thus description thereof is omitted.

If the freeze detection sensor 11 is placed on the water or on the road, it is possible to detect the frozen state of the water surface or the road surface.

FIGS. 7 to 10 show a freezing detection sensor for detecting icing on the aerial portion of equipment or structures used in cold regions or icy waters. The freeze detection sensor 21 is held by the holding body 22 or 22A, and
Band 24 (Figs. 7 and 8) and bolt 2
5 (FIGS. 9 and 10), the output of the sensor can be guided to another place such as an observation room or a control room, and the icing status can be displayed.

[0024]

As described above, in the freeze detection sensor of the present invention, the light incident portion formed on one surface of the triangular prism is connected to the light emitting device, and the light emitting portion formed on the other surface is connected to the discriminator.
It is composed of a plurality of sensor elements having the remaining one surface in contact with the liquid and a rod-shaped holder, and the sensor elements are provided at equal intervals on the holder. If the freezing detection sensor is arranged vertically on the water surface, the freezing detection sensor can detect the thickness of frozen ice with high accuracy and relatively low cost.

Further, if the freezing detection sensor is arranged in a plane on ice or on a road, it can detect freezing on the water surface or road surface as a freezing detection sensor for detecting freezing. Furthermore, if icing in the aerial part of equipment or structures used in cold regions or icy seas has a significant effect on the performance of the equipment or the stability of the structure, installation of a freezing detection sensor will detect icing. It is possible to predict the danger of icing as a freezing detection sensor.

[Brief description of the drawings]

FIG. 1 is a diagram showing light beam reflection and refraction for explaining the principle of a freeze detection sensor element of the present invention.

FIG. 2 is a diagram showing a power reflection coefficient for explaining the principle of the freeze detection sensor element of the present invention.

FIG. 3 is a front view showing a use state of the freeze detection sensor of the present invention.

FIG. 4 is a sectional view showing a freeze detection sensor element of the present invention.

FIG. 5 is a block diagram of a freeze detection sensor of the present invention.

FIG. 6 is a plan view of another embodiment of the freezing detection sensor of the present invention.

FIG. 7 is a plan view of an embodiment of a freeze detection sensor for detecting icing according to the present invention.

FIG. 8 is a side view of FIG. 7;

FIG. 9 is a plan view of another embodiment of a freeze detection sensor for detecting icing according to the present invention.

FIG. 10 is a side view of FIG. 9;

FIG. 11 is a block diagram of a conventional detection sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Freezing detection sensor 2 ... Holder 2a ... Hole 3 ... Sensor element 3a ... Triangular prism 3b ... Block 3c, 3d ... Rod lens 3e ... Sleeve 3f・ ・ Wetted surface 3g ・ ・ ・ Washer 4 ・ ・ ・ Box 5 ・ ・ ・ Light-emitting device 5a ・ ・ ・ Power supply 5b ・ ・ ・ Modulation circuit 5c ・ ・ ・ Switching circuit 5d ・ ・ ・ Light-emitting diode 6 ・ ・ ・ Discriminator 6a ... photodiode 6b ... amplifying circuit 6c ... threshold value judging circuit 6d ... calculating circuit 6e ... display 7,8 ... optical fiber 9 ... float 10 ... Ice thickness 11 ・ ・ ・ Freezing detection sensor 12 ・ ・ ・ Holder 13 ・ ・ ・ Sensor element 14 ・ ・ ・ Box 15 ・ ・ ・ Light emitter 16 ・ ・ ・ Discriminator 17, 18 ・ ・ ・ Optical fiber

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA30 BB13 BB23 CC00 DD03 FF44 GG07 HH04 HH12 JJ01 LL02 LL46 2G059 AA05 BB05 CC20 EE02 EE04 FF01 GG01 GG02 HH01 JJ11 JJ12 JJ17 KK03 PP01MM01

Claims (6)

[Claims] 1. A triangular prism having a predetermined included angle combined with a rod lens and an optical fiber,
A rod lens is attached and an optical fiber is connected so that the incident and reflection angles can be adjusted via washers, respectively, with the opposite surface of the included angle of the triangular prism as a liquid contact surface and the other two surfaces as a light incident portion and a light exit portion, respectively. A freezing detection sensor element. 2. The freezing detection sensor element according to claim 1, wherein two pairs of light incident and light emitting rod lenses attached to the prism are provided with different incident angles to improve accuracy. 3. The freezing detection sensor element according to claim 1, further comprising a light emitting device and a judging device, each being connected by the optical fiber. 4. A freezing detection sensor for measuring the thickness of ice inserted into a frozen water surface, wherein a rod-shaped holding member inserted into the frozen water surface is provided.
4. A freezing detection sensor, wherein a plurality of the freezing detection sensor elements according to any one of 3 to 3 are provided at equal intervals. 5. A freezing detection sensor inserted into a frozen water surface, a road surface or the like to detect the presence or absence of freezing, wherein a flat holding member inserted into the freezing surface is provided, and the holding member is provided. A freezing detection sensor, wherein a plurality of the freezing detection sensor elements according to any one of 1 to 3 are provided in a plane. 6. A freezing detection sensor for detecting icing of a detection part exposed to air, such as various devices and structures, and comprising an engagement means for engaging with the detection part. A freezing detection device comprising: a holder; and a plurality of the freeze detection sensors according to claim 1 provided on the holder.