JP2003172786A - Rainfall meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rainfall meter capable of surely introducing rainwater into a capillary, and advantageous for measuring the rainfall accurately by preventing an influence of dust included in the rainwater. <P>SOLUTION: This rainfall meter is constituted by providing in a casing 10 a water storage sub-tank 100 including a water receiving funnel (water collection means) 102 for accepting the rainwater, a water storage main tank (rainwater induction means) 200 for storing the rainwater collected by the water receiving funnel 102, and a measuring circuit (measuring means) 300 for measuring the instantaneous rainfall (change of rainfall) at the measuring time from dropping time intervals of waterdrops dropping down from the water storage main tank 200 through the capillary 210. In order to drop the rainwater in the water storage main tank 200 downward smoothly, at least the inner circumferential face of the capillary 210 is preferably formed from material having affinity for water. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rain gauge capable of measuring rainfall with a simple structure.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, for example, a visual type rain gauge using a water receiving funnel 1 and a measuring cylinder 2 is known. In this rain gauge, the rainwater that has entered the water receiving funnel 1 is stored in the graduated cylinder 2, and the amount of rainfall can be measured by looking at the scale of the graduated cylinder 2.
However, this rain gauge does not allow remote observation. Moreover, the unit time for measuring the rainfall cannot be easily changed, and it is difficult to measure the instantaneous rainfall. Therefore, recently, various rain gauges have been provided which measure the rainfall amount by electronic measuring means. For example, the falling trout type rain gauge shown in FIG. 4 drops rainwater that has entered the receiving funnel 3 onto the falling trout 4. The overturning mass 4 has bilaterally symmetrical measuring masses 4A, 4B for storing rainwater, and is supported by a bearing 5 so as to be able to fall over (Japanese Patent Publication No. 6-19477).
(See the official gazette). Then, one of the weighing cells 4A,
Each time the specified amount of rainwater is stored in 4B, each measuring cell 4A, 4
B alternately falls and presses the electric switches 6A and 6B provided corresponding to the respective weighing masses 4A and 4B. Thereby, the rainfall amount can be automatically measured by counting the detection pulses from the electric switches 6A and 6B.

Further, instead of the one using such a falling mass, there is known one which measures the amount of rainfall by measuring the weight of water (for example, Japanese Patent No. 2907480).
Issue). Further, it is known that rainwater is dropped from a storage tank in an oil tank, not the weight of water, and the number of water droplets is counted to measure the amount of rain (for example, Japanese Patent Laid-Open No. 6-66956).

[0004]

However, in the fall trout type rain gauge as described above, the rainfall cannot be measured unless the overturned trout accumulates more than a specified amount of rainwater. For example, at the beginning of rain or light rain. However, there was a problem that the rainfall could not be measured at any time. Further, the above-mentioned visual type rain gauge using a graduated cylinder measures an average amount of precipitation for a certain period of time, and the tipping trout type rain meter measures the time until a certain amount of rainfall is reached. There is a problem that the instantaneous value cannot be measured in either case. In addition, the tipping-mass type rain gauge has a mechanism that sends an electric signal when two alternating turning-overs of two weighing masses occur repeatedly, and the measurement results are affected by the frictional resistance of the moving parts, so maintenance and management of the bearings is possible. There was a problem that it was complicated.

Further, since a rain gauge for measuring the weight of water measures the amount of rainwater accumulated in a certain amount or more, when rain suddenly starts or when light rain changes to heavy rain, It is difficult to measure instantaneous rainfall. Furthermore, even in a rain gauge that drops rainwater from a storage tank in an oil tank and counts the number of water droplets, the configuration of dropping water droplets in the oil tank is complicated, and when rain suddenly starts or when heavy rain falls from heavy rain. It is difficult to measure the instantaneous amount of rainfall when it changes to.

In order to solve such a problem, the present applicant has already proposed that water collecting means for collecting rainwater, rainwater guiding means for guiding the rainwater collected by the water collecting means to a thin pipe, and through the thin pipe. Provided is a rain gauge equipped with a measuring means for measuring a rainfall amount from a dropping time interval of dripping water droplets. According to this rain gauge, the time interval of the water drop can be measured by the measuring means, and the instantaneous rainfall amount at the time of the measurement can be calculated from the dropping time interval of the water drop. In a rain gauge that drops water droplets from such a thin pipe, how to reliably guide the rainwater to the thin pipe in order to accurately calculate the rainfall,
How to prevent the influence of dust contained in rainwater is extremely important.

[0007] Therefore, an object of the present invention is to provide a rain gauge which can reliably guide rainwater to a thin pipe and can accurately calculate the rainfall amount by preventing the influence of dust contained in the rainwater. It is in.

[0008]

In order to achieve the above object, the present invention provides a water collecting means for collecting rainwater, rainwater guiding means for guiding the rainwater collected by the water collecting means to a thin pipe, and through the thin pipe. In a rain gauge comprising measuring means for measuring a rainfall amount from a dropping time interval of dripping water droplets, the thin tube is
It has a cylindrical wall extending in the vertical direction and a cylindrical hole formed in the inner peripheral surface of the cylindrical wall and extending in the vertical direction, and at least the inner peripheral surface of the cylindrical wall has an affinity for water. It is characterized by being formed of a material. Therefore, according to the present invention, when it rains, the rainwater is received by the water collecting means and guided to the thin tube by the rainwater guiding means. Since at least the inner peripheral surface of the cylindrical wall of the thin tube is formed of a material having an affinity for water, the water is reliably guided along the hole and dripped downward.

The present invention is also directed to water collecting means for collecting rainwater, rainwater guiding means for guiding the rainwater collected by the water collecting means to a thin pipe, and rain from a drip time interval of water drops dripping through the thin pipe. In a rain gauge comprising a measuring means for measuring an amount, the thin tube has a cylindrical wall extending in a vertical direction, and a cylindrical hole extending in a vertical direction formed on an inner peripheral surface of the cylindrical wall. However, a material having an affinity for water is contained in the holes. Therefore, according to the present invention, when it rains, the rainwater is received by the water collecting means,
It is guided to a thin pipe by rainwater guiding means. Since the material having an affinity for water is contained in the hole of the thin tube, the water is surely guided along the hole and dripped downward.

Further, according to the present invention, there is provided a water collecting means for collecting rainwater, a water tank for storing rainwater collected by the water collecting means, and a water tank provided so as to project downward from a bottom surface of the water tank. In a rain gauge comprising a thin tube into which rainwater flows in, and a measuring means for measuring a rainfall amount from a drip time interval of water droplets dripping through the thin tube, a filter member having an affinity for water is housed in a hole of the thin tube. It is characterized by being Therefore, the dust contained in the rainwater is filtered by the filter member.

Further, according to the present invention, there is provided a water collecting means for collecting rainwater, a water tank for storing rainwater collected by the water collecting means, and a water tank provided so as to project downward from a bottom surface of the water tank. In a rain gauge comprising a thin tube into which rainwater flows in and a measuring means for measuring the amount of rainfall from a dropping time interval of water droplets dripping through the thin tube, a filter member having an affinity for water covers the bottom surface of the water tank. It is provided in. Therefore, the dust contained in the rainwater is filtered by the filter member.

Further, according to the present invention, a water collecting means for collecting rainwater, a rainwater guiding means for guiding the rainwater collected by the water collecting means to a thin tube, and a drip time interval of water drops dripping through the thin tube are measured. Drip time interval measuring means, correcting means for correcting the surface tension of water by the temperature of the rainwater introduced to the rainwater guiding means, the outer diameter of the tip surface of the thin tube, the corrected surface tension of the water, and The specific gravity of water is 1 by calculating the total weight of the water droplets obtained by the weight measuring means and the weight measuring means for obtaining the weight of the water droplet for each water droplet from the dropping time interval of the water droplet. Therefore, by converting the weight into a volume, a rainfall amount calculating means for calculating an average rainfall amount per hour by dividing the sum of the calculated weight of the water droplets by the unit time, To do. Therefore, according to the present invention, the weight of the water drop dropped from the thin tube is calculated by the surface tension corrected by the water temperature and the drop time interval of the water drop. The average amount of rainfall per hour is calculated by dividing the total weight of water droplets calculated for each unit time by the unit time.

Further, according to the present invention, water collecting means for collecting rainwater, rainwater guiding means for guiding the rainwater collected by the water collecting means to a thin pipe, and rain from a dropping time interval of water drops dripping through the thin pipe. In a rain gauge equipped with a measuring means for measuring the amount, a plurality of thin tubes having different outer diameters are provided for the one rainwater guiding means, and the measuring means detects water droplets dripping from each of the thin tubes. The feature is that the amount of rainfall is measured by. Therefore, according to the present invention,
Since small water droplets and large water droplets can be formed by capillaries having different outer diameters, it is possible to measure rainfall with high resolution with small water droplets, and to measure when there is a lot of rainwater with large water droplets.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a rain gauge for remote observation according to the present invention will be described below. FIG. 1 is a schematic sectional view showing the structure of a rain gauge for remote observation according to a first embodiment of the present invention. The rain gauge of this example has, as a basic configuration, a sub water storage tank 100 including a water receiving funnel (water collecting means) 102 for receiving rain water, and a main water storage tank for storing rain water collected by the water receiving load 102 ( Rainwater guiding means) 200 and a thin pipe 210 from the main water tank 200
A measuring circuit (measuring means) 300 for measuring the instantaneous rainfall amount (change in rainfall amount) at the time of measurement from the dropping time interval of the water droplets dripping through is provided in the housing 10.

The water receiving funnel 102 is formed in a funnel shape and has a large diameter opening to the sky. The rainwater is collected from the water receiving funnel 102 and is supplied to the main water tank 200 below. It is a thing. The sub water tank 100 is
It is composed of the water receiving funnel 102 and the upper edge portion of the housing 10, and functions as a water tank when the amount of rainfall is large. The water receiving funnel 102 has a guard 1 on the upper surface.
10 and a filter 120 are provided, and an overflow pipe 130 is provided laterally. The guard 110 is
For example, it is for hail resistance and for preventing tampering, and is formed, for example, in a lattice shape, and protects the upper opening (especially filter 120) of the water receiving funnel 102 from falling of hail, fallen leaves, etc., or mischief of an innocent person. To do. The filter 120 is
It removes dust and oil smoke contained in rainwater.For example, a filter paper, etc., which has as little water retention as possible and allows rainwater to pass quickly downward so as not to impair the responsiveness of this rain gauge is used. I shall. The overflow pipe 130 discharges rainwater overflowed in the sub water storage tank 100 to the outside of the housing 10.

The main water tank 200 has a bottom surface 202.
And a side surface 204 that stands up from the periphery of the bottom surface 202, and is formed in a tank shape so as to store rainwater that has fallen from the water receiving funnel 102 in a space surrounded by the bottom surface 202 and the side surface 204. In this main water tank 200,
A thin tube 210, a water temperature measuring device 220, and an overflow prevention valve 230 are provided. This main water tank 200
Is for storing rainwater when the amount of rainfall becomes larger than a certain amount.
The rainwater falling from 02 is guided to the thin tube 210 without staying in the main water tank 200 for a long time. Therefore, the bottom surface of the main water storage tank 200 is configured to guide the rainwater falling from the water receiving funnel 102 to the thin tube 210 as quickly as possible. For example, as it gets closer to the thin tube 210, it is formed in an inclined surface shape that is gradually inclined downward, or a plurality of grooves connected to the thin tube 210 are formed, and rainwater flows into the thin tube 210 along the grooves. . Note that the illustrated example is an example in which it is formed in an inclined surface shape. In addition, when it rains heavily,
The amount of rainfall becomes larger than the maximum dropping amount of the thin tube 210, and the rainwater starts to accumulate in the main water tank 200.
It will be determined based on the maximum dropping amount of 0 and the opening area of the water receiving funnel 102. Therefore, in the rain gauge of this embodiment, based on the instantaneous rainfall amount to be measured, the thin pipe 21
The size of 0 and the opening area of the water receiving funnel 102 are designed so that the beginning of rain can be measured with a relatively high response to a heavy rainfall of about several tens of millimeters.

The thin tube 210 is for dropping water drops of rainwater in the main water storage tank 200 downward.
00 has a cylindrical wall extending downward from the bottom surface 202 and extending in the vertical direction, and a cylindrical hole formed in the inner peripheral surface of the cylindrical wall and extending in the vertical direction. It is connected to the bottom surface 202. Further, the thin tube 210 has a tip surface having an outer diameter dimension necessary to obtain a desired maximum dropping amount for the reason described above, and the tip surface of the thin tube 210 extends in the extending direction of the thin tube 210. On the other hand, it is formed so as to be a plane that is perpendicular to it, and is processed so as to be a mirror surface. The thin tube 210 is preferably made of a material having an affinity for water, at least the inner peripheral surface of which, in order to allow rainwater in the main water tank 200 to drop downward without interruption. For example, even if the thin tube 210 is made of a material having an affinity for water, or if a material having an affinity for water is provided on the inner peripheral surface, a material having an affinity for water is applied to the inner peripheral surface. May be. The water temperature measuring device 220 is the main water tank 2
The temperature of rainwater is measured within 00. The water temperature data detected by the water temperature measuring device 220 is used to calculate the surface tension of rainwater and the like. Although not specifically shown in FIG. 1, in the rain gauge of the present embodiment, a large amount of rain water is not stored in the main water tank 200 under normal rain.
In order to detect the temperature of this rainwater, for example, a groove through which the rainwater passes toward the thin tube 210 is provided on the bottom surface of the main water storage tank 200, and a detector of the water temperature measuring device 220 is arranged in this groove, so that a small amount of water can be detected. The temperature of rainwater is measured as reliably as possible. The overflow prevention valve 230 opens and closes the water receiving funnel 102 in conjunction with the float 232 arranged in the main water tank 200, and when the water level in the main water tank 200 exceeds a certain height, the water receiving funnel It is intended to prevent rainwater from dropping from 102 and to prevent overflow on the main water tank 200 side. As described above, in the rain gauge of the present embodiment, since the rainwater does not collect in the main water tank 200 under normal rain, the overflow prevention valve 230 functions in the case of abnormal heavy rain.

The measuring circuit 300 detects water drops dripping from the thin tube 210 of the main water tank 200 by the optical sensor 400, and calculates each data such as instantaneous rainfall based on the detection signal. The optical sensor 400 is a thin tube 2.
A light emitting unit 410 and a light receiving unit 420 are arranged on both left and right sides of a drop path of water drops falling from 10 on both sides. The light emitting section 410 is, for example, a light emitting diode or a laser diode, and the light receiving section 420 is, for example, a photodiode or the like. Then, the light from the light emitting unit 410 is emitted from the thin tube 210.
The measuring circuit 300 measures the time interval at which the water drops fall by being intermittently blocked by the further falling water drops and detecting the state of this light by the light receiving unit 420. Also,
A drain pipe 140 is provided in the lower part of the housing 10, and the rainwater that has dropped into the housing 10 is discharged to the outside of the housing 10.

FIG. 2 is a block diagram showing the configuration of the measuring circuit 300 of the rain gauge for remote observation according to the first embodiment of the present invention. The measurement circuit 300 includes a temperature / surface tension correction circuit 310, a time average rainfall amount calculation circuit 320, a water drop number counter 330, a time interval τ1 setting circuit 340,
Instantaneous rainfall calculation circuit 350 and time interval τ2 measurement circuit 3
60, a pulse generation circuit 370, and a measurement method changeover switch 380.

The temperature / surface tension correction circuit 310 is a circuit for correcting the data of the temperature and surface tension used for measuring the rainfall amount based on the detection signal from the water temperature measuring device 220.
The time average rainfall calculation circuit 320 uses the water drop counter 33.
It is a circuit that calculates a time average rainfall amount for a preset time interval τ1 based on a count value of 0. The water drop counter 330 includes a pulse signal output from the pulse generation circuit 370 and a time interval τ1 setting circuit 340.
The number of water droplets for the time interval τ1 used in the time average rainfall amount calculation circuit 320 is counted based on the time interval τ1 set in (1). Time interval τ1 setting circuit 34
0 is for setting the time interval τ1 used in the time average rainfall calculation circuit 320.

The instantaneous rainfall calculation circuit 350 calculates the time interval τ
2 is a circuit that calculates the instantaneous rainfall based on the time interval τ2 measured by the two-measurement circuit 360. The time interval τ2 measurement circuit 360 is a circuit that measures the time interval τ2 of water drops used in the instantaneous rainfall amount calculation circuit 350 based on the pulse signal output from the pulse generation circuit 370. The pulse generation circuit 370 is a circuit that generates a pulse signal corresponding to the detection signal output from the light receiving section 420 of the optical sensor 400. The measurement method changeover switch 380 is a switch for switching between measuring the instantaneous rainfall amount and the average rainfall amount, and operates to switch the output path of the pulse generation circuit 370.

Next, detailed functions and operations of the rain gauge for remote observation having the above configuration will be described. First, in FIG. 1, rainwater passes through the uppermost hail-resistant and tamper-proof guard 110 that prevents dead leaves and gravel, and then the filter 120
After the sand dust and oil smoke are filtered by, the water is collected by the water receiving funnel 102 and poured into the main water tank 200. Rainwater passes from the bottom of the main water tank 200 through the thin tube 210 and drops. At this time, the weight m of the water droplet is determined by the thin tube 210 having a circular cross section.
It is expressed by the following equation using the radius r of the outer diameter of the tip surface of and the surface tension γ of water. mg = 2πrγ (1) where g is the gravitational acceleration. Since the surface tension of water depends on the temperature, the water temperature of the main water tank 200 is measured, and the surface tension at that temperature is set in the measurement circuit 300 in advance to correct m.

The water droplets dripped from the thin tube 210 are light emitting parts 41.
It traverses a thin light beam with a diameter of 1 mm or less radiated from 0. The light receiving section 420 may be installed so as to directly receive the light beam in the steady state, or may be installed in a place where the light beam does not enter in the steady state. When the position of the light receiving unit 420 is the former, water is detected by the light being blocked by the falling of the water droplet. When the position of the light receiving unit 420 is the latter, the light receiving unit 420 receives scattered light from the water droplet, thereby detecting the water droplet. By detecting such water droplets, the number n of water droplets is counted at a constant time interval τ1, the number of water droplets is multiplied by m, and this is divided by the area S of the receiving funnel 102 to obtain the amount of precipitation per hour τ. This one
If it is multiplied by time / τ1 hour, the amount of precipitation per hour becomes M. This is the method of measuring rainfall during the average time. That is, if τ1 is a unit of seconds, the following is obtained. M = 3600 ・ m ・ n / (S ・ τ1) (2)

Next, for the instantaneous rainfall, the time interval τ2 from the dropping of a water drop to the next dropping is measured, and this is converted into rainfall per hour. When τ2 is expressed in seconds, the rainfall amount per hour M is as follows by converting the weight into volume because the specific gravity of water is 1. M = 3600 · m / (S · τ2) (3) The measurement circuit 300 performs the above calculation. Further, in FIG. 1, the dropped water drops are the drain pipe 1
Drain through 40. In normal rain, the water that has flowed into the main water storage tank 200 is dripped from the thin tube 210 as it is and is not stored in the main water storage tank 200 for a long time. Therefore, at the beginning of heavy rainfall, the time interval of water droplets and the amount of rainfall are proportional, and effective instantaneous rainfall can be measured.By observing the change in this instantaneous rainfall, It is possible to predict the arrival.

When the water depth of the main water tank 200 becomes a certain level or more due to heavy rain, the overflow prevention valve 230
Shuts off the water receiving funnel 102, suppresses the water depth of the main water tank 200, and prevents water pressure other than surface tension from being applied to the portion of the thin tube 210. This gives 100 per hour
The size of the water droplets is stabilized even in the case of heavy rain reaching mm, so that the proper measurement state can be maintained. Further, when the water receiving funnel 102 is cut off by heavy rain, the water receiving funnel 102 functions as a water storage tank. And the case 1
The length dimension of 0 is determined depending on the weather conditions of the use area, and is extended above the water receiving funnel 102 in an area where rainfall is large. For example, 10 cm above
When it is extended, even if there is a rainfall of 100 mm in a moment, the rainfall amount can be stored by the first storage tank 100. In addition, the overflow pipe 1 of the sub water tank 100
The reference numeral 30 drains the unprocessable rainwater when there is more rainfall than expected. With such a configuration, damage caused by heavy rain can be minimized, and once the heavy rain has stopped, each water tank 10 can be maintained without maintenance.
It is possible to drain 0,200 of water through the thin tube 210 and return to the observable state again.

Next, the operation of the measuring circuit 300 will be described with reference to FIG. The pulse generation circuit 370 creates a single pulse based on the detection signal of the light receiving unit 420, and the water droplet number counter 330 passes through the measurement method switching circuit 380.
Alternatively, the pulse output is supplied to the time interval τ2 measuring circuit 360. Then, when the average rainfall amount is measured by the equation (2), the pulses during the constant time interval τ1 are counted by the water droplet number counter 330, and the rainfall amount is calculated by the time average rainfall amount calculation circuit 320. Further, when the instantaneous rainfall is measured by the equation (3), the time interval τ2 measuring circuit 360 measures the time interval τ2 between the two pulses, and the instantaneous rainfall calculating circuit 350 calculates the rainfall amount based on this. calculate. Also,
In the temperature / surface tension correction circuit 310, the sub water tank 100
The water temperature is measured, and from the relationship between the water temperature and the surface tension, the formula (2)
And the weight m of the water drop used in equation (3) is corrected. The result of the measurement by the measuring circuit 300 is transmitted to a remote management center or a terminal device owned by an individual manager through a connector or the like by wire or wirelessly, and is displayed on a monitor or the like. As a result, a remote manager can grasp the amount of rainfall.

In the case of performing the measurement work with the remote observation rain gauge as described above, first, when the amount of rainfall is large, the instantaneous rainfall amount for measuring the time interval τ2 between the water droplets and the water droplets is calculated using the equation (3). The maximum allowable rainfall of the rain gauge is, for example, 10
The diameter of the upper opening of the receiving funnel 102 and the thin tube 21 are set to 0 mm in advance so that the hourly rainfall can be measured.
The maximum dropping amount of 0 is determined. The maximum dropping amount of the thin tube 210 is
Even if the maximum flow rate of the thin tube 210 is reached, water drops are prevented from forming a continuous flow. To adjust the maximum flow rate of the thin tube 210, for example, pressure is applied from the outside of the thin tube 210 to the thin tube 21.
It can be adjusted by mechanically deforming the inner diameter of zero. Further, in order to adjust the size of the water droplet, it is necessary to change the outer diameter of the tip end surface of the thin tube 210. Therefore, for example, a tube having a different outer shape is selected and used, or a thick tube is prepared in advance. , The tip is ground and adjusted to the desired outer diameter. Further, the area of the water surface of the main water tank 200 is set to be a large area which is more than half the area of the water receiving funnel 102, and the temporal nonuniformity of raindrops falling on the water receiving funnel 102 is averaged. This improves the accuracy of the instantaneous measurement value.

When the amount of rainfall is small or when the conditions are matched with the measurement time interval of the visual observation using a normal measuring cylinder, the method using the formula (2) is adopted. In this case, the number of water droplets within the fixed time τ1 is counted to suppress the fluctuation of the interval at which the water droplets drop from the thin tube 210. In addition, when the measurement is performed a plurality of times during τ1 hour by the method using the equation (3) and the average value thereof is obtained, the same measurement result as the method according to the equation (2) is obtained in principle.

With the rain gauge for remote observation according to this embodiment as described above, the following effects can be obtained. (A) Rainfall can be measured at very short time intervals, such as every few minutes. That is, if there is a lot of rainfall
Set to a few minutes, and if the amount of rainfall is small, you can measure the instantaneous rainfall and measure with good response. (B) Both the instantaneous rainfall amount at the time of measurement and the average rainfall amount for a fixed time can be measured. That is, by remotely controlling the switching of the measurement method and selecting the method using the equation (2) or the method using the equation (3), either the quick measurement of the response or the measurement of the general average value is performed. You can choose the better one.

(C) An observer is not required beside the rain gauge, and automatic observation can be performed by transmitting the measurement result to a remote place. With the configuration shown in FIG. 2, the rain gauge is entirely automated, and the measurement result can be transmitted to a communication terminal device at a remote place by wire communication or wireless communication. In addition, it is possible to select the measurement of the time-average rainfall amount by the above-mentioned formula (2) and the measurement of the instantaneous rainfall amount by the formula (3) by the control signal from the communication terminal device at the remote place. (D) The rainfall observation section has no moving parts and is easy to maintain and manage. As shown in FIG. 1, sand dust or oil smoke contained in rainwater is filtered by a filter 120 so that a thin tube 210 that determines the size and the number of drops of water is not blocked. Also,
Since the mechanical strength of the filter 120 becomes weak when it gets wet, the guard 110 is provided. The guard 110 protects the surface of the filter 120 from being soiled by fallen leaves and is prevented from being damaged by a natural phenomenon such as hail or mischief. By eliminating the possibility of contamination or damage, it becomes possible to regularly replace the filter after the season when the filter 120 such as yellow sand or dust becomes dirty.

When the thin tube 210 is made of a metal material or a plastic material having good workability, water enters the hole of the thin tube 210 by the repulsive force due to its surface tension when the inner peripheral surface of the thin tube 210 is dry. Phenomenon that cannot be included occurs. Therefore, at the beginning of rainfall, water is stored in the main water storage tank 200 until the pressure at which water enters the holes of the thin tubes 210 is reached, so that there is a delay from the start of rainfall to the start of dropping of water droplets from the thin tubes 210. In this embodiment,
Since at least the inner peripheral surface of the thin tube 210 is made of a material having an affinity for water, the main water tank 200
The rainwater inside is smoothly guided to the hole of the thin tube 210 and can be dripped downward without any delay, and it is possible to prevent a time delay in measuring the rainfall amount, which is advantageous in accurately calculating the rainfall amount. .

The same effect can be obtained by forming at least the inner peripheral surface of the thin tube 210 with a material having an affinity, and by containing a material having an affinity for water in the hole of the thin tube 210. it can. That is, the rainwater in the main water storage tank 200 can be smoothly guided to the hole of the thin tube 210 by the material contained in the hole of the thin tube 210, and can be dripped downward without delay. Further, since the material is contained in the hole of the thin tube 210, the amount of water flowing from the thin tube 210 can be adjusted, the water flowing from the thin tube 210 is prevented from becoming a continuous flow, and water drops are surely dropped. This is advantageous in accurately calculating the rainfall amount. As the material, for example, glass fiber can be used, and the accommodation of the glass fiber in the holes can be carried out so that capillary action occurs between the glass fibers along the extending direction of the holes. It is preferable for smoothly guiding along the extending direction of the hole.

Next, a second embodiment will be described.
In the second embodiment, the first point is that the thin tube 210 is provided with a filter member for filtering dust that flows with water.
Different from the embodiment. FIG. 3 is a cross-sectional view of a main water tank and a thin tube showing a configuration example in which a filter member is provided in the thin tube. In this example, the bottom surface 20 of the main water tank 200
The hole 212 of the thin tube 210 provided in No. 2 is composed of a large diameter portion 214 connected to the bottom surface and a small diameter portion 216 formed with an inner diameter smaller than the large diameter portion 214. A filter member 218 having an affinity for water is housed in the large diameter portion 214. The filter member 2
It suffices that 18 is made of a material that filters dust, allows water to pass through, and has an affinity for water, and for example, many glass fibers can be used. In glass fiber, a capillary phenomenon strongly occurs in the fiber direction.
Therefore, it is necessary to store the glass fibers in the large diameter portion 214 so that a capillary phenomenon occurs between the glass fibers along the extending direction of the holes.
It is preferable in order to smoothly guide it to the lower side of 12. Of course, the material 218 may use materials other than glass fiber.
According to the above configuration, by filtering the dust contained in the rainwater by the filter member 218, it is possible to prevent the hole of the thin tube 210 from being clogged with dust and hindering the dropping of water droplets, and calculating the rainfall amount. This is advantageous for accurate execution. In addition, the filter member 218 is a thin tube 210.
Since it is only accommodated in the large-diameter portion 214, the amount of water remaining in the filter member 218 due to the capillary phenomenon at the beginning of rainfall is small, which is advantageous in reducing the rainfall measurement error.

FIG. 4 is a cross-sectional view of the main water tank and the thin tube showing an example of the structure in which the filter member is provided on the bottom surface of the main water tank. As shown in FIG. 4, the filter member 2 covers almost the entire bottom surface 202 of the main water tank 200B.
19 are provided. According to the above configuration, by filtering the dust contained in the rainwater by the filter member 218, it is possible to prevent the hole of the thin tube 210 from being clogged with dust, which prevents the drop of water droplets from being hindered, and calculates the rainfall amount. It is advantageous in accurately performing. As the material of the filter member 219, the same material as in the case of FIG. 3 may be used. In glass fiber, a capillary phenomenon strongly occurs in the fiber direction. Therefore, the glass fibers may be accommodated so that the capillary action occurs along the bottom surface 202 between the glass fibers.
It is preferable for smoothly leading to the 0 hole 212. Of course, the material 218 may use materials other than glass fiber. Further, according to this configuration, the filter member 21
Even if the surface of 9 is covered with dust, water permeability is ensured in the extending direction of the filter member 219. Therefore, it is not necessary to replace the filter member 219 until the entire surface of the filter member 219 is covered with dust, and the filter is replaced. Since the time can be extended, it is advantageous in improving maintainability.

Next, a third embodiment will be described.
The third embodiment is different from the first embodiment in that the rainfall amount is calculated in consideration of the fact that the drop interval of water drops affects the weight of water drops. First, the principle of calculating the rainfall will be described. As described above, the weight m of water droplets is determined by the outer diameter of the thin tube 210 being φ, the surface tension of water being γ,
When the gravitational acceleration is g, it is expressed by the following equation (1-1). mg = πφγ (1-1) In the following, γ is omitted by changing the unit system. As shown in the science chronology, the surface tension γ of water changes depending on the water temperature. This surface tension γ is represented by the following equation (1-2) when it is represented by a linear equation with the water temperature T (Celsius) as a variable. γ = 75.62−0.1435T (1-2) (However, coefficient 75.62 and coefficient 0.1435 are examples, and T> 0 degrees)

The weight of the water droplet is calculated based on the water temperature and the dropping interval using the above equations (1-1) and (1-2). Thin tube 2
The outer diameter φ of 10 and the weight of water droplets are represented by the equation (1-1),
According to the actual measurement, there is an initial value even if the outer diameter φ is 0, and (1
By substituting γ in the equation (-2), the equation (1-3) is obtained from the equation (1-1). m ₀ = m ₁ + (15.7-0.0298T) φ (1-3) The weight m ₀ of the water droplet when the dropping time of the water droplet is long is the thin tube 2
It is expressed in the form of a linear expression like the expression (1-3) using the outer diameter φ of 10. Since m _{1 of} the first term on the right-hand side has a very small amount of water droplets attached due to surface tension even if the outer diameter of the thin tube 210 is zero, its weight is 4 mg (milligram), and the temperature dependence of the surface tension γ is shown in parentheses in the second term. Show. In this formula, the outer diameter φ is mm
Substituting in (millimeter) units, the weight m _{0 of the} water droplet is m
It is calculated in units of g (milligram).

In the present embodiment, the fact that the weight of the water drop is influenced by the time interval of the drop is incorporated into the equation. The relational expression for calculating the water drop weight from the dropping interval can be represented by a quadratic expression or a curve expression such as an exponential function. For example, when expressed by an exponential function, it is expressed by equation (1-4). m = m ₀ exp (A / t) (1-4) Here, t is the time interval until the water droplet falls, m is the weight of the water droplet, and m ₀ is the weight when t is sufficiently long. Thin tube 2
When the outer diameter φ of 10 is 3 mm, m ₀ is 50.5 mg and A is 51 ms when the water temperature is 20 degrees. Using this equation (1-4), the weight of the water drop is calculated for each time interval of dropping one drop at a time. Therefore, the amount of rainfall can be continuously measured from the weight of the water drops.

FIG. 5 is a block diagram showing the configuration of the measuring circuit 300 of the rain gauge for remote observation according to the third embodiment. 5, the same parts as those in FIG. 2 showing the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The measurement circuit 300A has a time interval t measurement circuit 360A.
And a weight measurement / rainfall calculation circuit 390 and a pulse generation circuit 370.

The time interval t measurement circuit 360A is a circuit for measuring the time interval t of water drops used in the weight measurement / rainfall amount calculation circuit 390 based on the pulse signal output from the pulse generation circuit 370.

The weight measurement / rainfall amount calculation circuit 390 corrects the weight of the water drop based on the water temperature T measured by the water temperature measuring means 220 and the equation (1-3), and is measured by the time interval t measurement circuit 360A. Based on the time interval t and the equation (1-4), the weight of water drops is calculated for each time interval of dropping one drop, and the weights of the water drops are summed for a predetermined unit time. This is a circuit that calculates the average amount of rainfall per hour by converting the weight into a volume and dividing the total weight of water drops by the unit time. In the present embodiment, the weight measurement / rainfall amount calculation circuit 390 constitutes the correction unit, the weight measurement unit, and the rainfall amount calculation unit in the claims.

Next, the operation of the measuring circuit 300A will be described with reference to FIG. The pulse generation circuit 370 forms a single pulse based on the detection signal of the light receiving section 420 and supplies the pulse output to the time interval t measurement circuit 360A. Based on the water temperature T measured by the water temperature measuring means 220 and the time interval t measured by the time interval t measuring circuit 360A, the weight measurement / rainfall amount calculation circuit 390 calculates the water drop at every time interval of dropping one drop at a time. The weight is calculated, the weights of the water droplets are summed for a predetermined unit time, and the summed water droplet weights are divided by the unit time to calculate an average rainfall amount per hour. The result of the measurement by the measuring circuit 300A is transmitted to a management center at a remote place or a terminal device owned by an individual manager through a connector or the like by wire or wirelessly, and is displayed on a monitor, etc. Similar to the first embodiment, the amount can be grasped. According to the above-described embodiment, the weight of the water droplet is corrected according to the time interval of dropping the water droplet, so that there is an effect that a more accurate rainfall amount can be calculated.

Next, a fourth embodiment will be described.
The fourth embodiment is different from the first embodiment in that the upper limit of the measurable rainfall amount is expanded by providing a plurality of thin tubes in the main water tank. First, the upper limit of the amount of rainfall that can be processed for each thin tube by providing multiple thin tubes,
That is, the maximum processing amount will be described. When the outer diameter of the thin tube is determined, the weight of the water droplet is determined, and when the area S of the water receiving funnel is determined, the resolution and maximum throughput of the thin tube are determined. Assuming that the weight of the water drop is constant at m regardless of the water temperature and the dropping time interval, and the minimum dropping time interval is τ3, the resolution per droplet and the maximum throughput per second are expressed by the following equation (2-1), ( 2-
It is shown in a proportional relationship as in the equation (2). Resolution = m / S (2-1) Maximum throughput = (m / τ3) / S (2-2) Here, according to the equation (2-1), if the water drop weight is small, the resolution is It can be seen that it can be made smaller, which is preferable. It is also understood that the larger the weight of water droplets, the more preferable in order to increase the maximum treatment amount.

In reality, if S has a diameter of 20 cm and the outer diameter of the thin tube is 3 mm, the resolution is 0.0016 mm, which is sufficiently small.
It cannot cope with heavy rain of 5 mm or more. If a plurality of thin tubes are provided in order to cope with such a heavy rain, the throughput can be increased. If the outer diameters of the thin tubes are the same, (2-1)
The maximum processing amount of the equation (2-2) can be increased without changing the resolution of the equation. However, it is preferable that the number of thin tubes is as small as possible in order to suppress the manufacturing cost. In order to minimize the number of capillaries, it is sufficient to provide capillaries for producing large water droplets and capillaries for producing small water droplets with good resolution, as described below, in order to increase the throughput.

That is, a first thin tube for dropping small water droplets and a second thin tube for dropping water droplets larger than the first thin tube are provided in the main water storage tank. The outer diameter of the first thin tube is smaller than the outer diameter of the second thin tube. When the amount of rainwater stored in the main water tank is less than or equal to a predetermined amount, the rainwater is guided only to the first thin tube, and the amount of rainwater stored in the main water tank exceeds the predetermined amount. Sometimes, it is configured to guide rainwater to both the first thin tube and the second thin tube. Specifically, the upper end position of the second thin tube is arranged higher than the upper end position of the first thin tube. Thereby, if the rainwater does not exceed the predetermined amount, the water is guided only to the first thin tube, and if the rainwater exceeds the predetermined amount, the water is guided to the first and second thin tubes.

The measurement of the water droplets dripping from each thin tube is provided with a measuring means consisting of a light emitting part and a light receiving part for each thin tube, and the dropping time interval of the water drops dripping from each thin tube is measured by each measuring means. By doing so, the amount of rainfall can be measured. According to such a fourth embodiment, when the amount of rainwater stored in the main water tank is less than or equal to a predetermined amount, the rainwater is guided only to the first thin pipe, so that the first thin pipe The small drops of water that are dropped enable high-resolution measurement of rainfall. Further, when the amount of rainwater stored in the main water tank exceeds the predetermined amount, the rainwater is guided to both the first thin pipe and the second thin pipe. Can be large.

Further, in the above configuration, since the measuring means is provided for each thin tube, there is a demerit that the number of measuring means increases. In order to solve this, for example, the following configuration can be adopted. That is, a plurality of light emitting elements that are provided for each thin tube and irradiate the water droplets with light intensity-modulated at different frequencies, one light receiving element that receives scattered light that is radiated to the water droplets and scattered, and the light receiving element A detecting unit is provided which determines, based on the detection signal detected by the element, which thin tube the scattered light received by the light receiving element is, and which detects the drop time interval of the water droplet for each thin tube. Thus, the amount of rainfall may be measured based on the time intervals of water droplets detected by the detecting means for each thin tube.

The case where one each of the first thin tube and the second thin tube is provided will be described in detail. The weight of water droplets in the first thin tube is m1, the number of water droplets dropped in a certain period of time is n1, and the weight of water droplets in the second thin tube is m1.
2. Let n2 be the number of water droplets dripped within a certain period of time, and substitute them into the equation (2) of the first embodiment described above to obtain respective sum totals M1 and M2, and calculate the average rainfall amount M from these sums.
Ask for. M1 = 3600 · Σm1 / (S · τ41) …… (3-1) (Σ indicates the total number of water droplets n1) M2 = 3600 · Σm2 / (S · τ42) …… (3-2) (Σ is M = M1 + M2 (3-3) (where τ41 is the dropping time interval of the first thin tube, and τ42 is the dropping time interval of the second thin tube).

Similarly, the instantaneous rainfall is also obtained by measuring the dropping time intervals and calculating and adding for each thin tube. Ms1 = 3600 · m1 / (S · τ51) …… (3-4) Ms2 = 3600 · m2 / (S · τ52) …… (3-5) Ms = Ms1 + Ms2 …… (3-6) (however, τ51 Is the time interval of dropping of the first thin tube, and τ52 is the time interval of dropping of the second thin tube)

According to such a configuration, since only one light receiving element constitutes the measuring means, the structure of the measuring means can be simplified and it is advantageous in reducing the cost.

[0050]

As described above, according to the rain gauge of the present invention, it is possible to prevent the measurement delay of the rainfall amount at the beginning of rainfall by surely guiding the rain water to the thin tube, and to accurately calculate the rainfall amount. It is advantageous above. Further, by providing a filter member for removing dust, it is advantageous to prevent clogging of the thin tube and the like, thereby accurately calculating the rainfall amount. Further, according to the rain gauge of the present invention, the measurement accuracy of the rainfall amount can be improved by accurately measuring the weight of the water droplet. In addition, it is possible to measure the amount of rainfall in both normal rainfall and heavy rainfall.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the structure of a rain gauge for remote observation according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a measuring circuit of the rain gauge for remote observation according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a main water tank and a thin tube showing a configuration example in which a filter member is provided on the thin tube in the second embodiment.

FIG. 4 is a cross-sectional view of a main water tank and a thin tube showing a configuration example in which a filter member is provided on the bottom surface of the main water tank in the second embodiment.

FIG. 5 is a block diagram showing a configuration of a measuring circuit 300 of a rain gauge for remote observation according to a third embodiment.

FIG. 6 is an explanatory diagram showing a specific example of a conventional visual type rain gauge.

FIG. 7 is an explanatory diagram showing a specific example of a conventional tipping-mass type rain gauge.

[Explanation of symbols]

10 ... Housing, 100 ... Sub water tank, 102 ... Water receiving funnel, 200 ... Main water tank, 210 ... Thin tube, 2
18, 219 ... Filter member, 300 ... Measuring circuit,
310: Temperature / surface tension correction circuit, 320: Time-averaged rainfall amount calculation circuit, 330: Water drop number counter, 340
...... Time interval τ1 setting circuit, 350 …… Instantaneous rainfall calculation circuit, 360 …… Time interval τ2 measuring circuit, 360A ……
Time interval t measurement circuit, 370 ... Pulse generation circuit, 38
0 …… Measuring method switch, 390 …… Weight measurement / rainfall calculation circuit.

Claims (36)

[Claims] 1. A rainfall collecting means for collecting rainwater, a rainwater guiding means for guiding the rainwater collected by the water collecting means to a thin tube, and a rainfall amount is measured from a drip time interval of water droplets dripping through the thin tube. In a rain gauge comprising a measuring means, the thin tube has a cylindrical wall extending in the vertical direction, and a cylindrical hole extending in the vertical direction formed by the inner peripheral surface of the cylindrical wall, the cylinder A rain gauge, characterized in that at least the inner peripheral surface of the wall is formed of a material having an affinity for water. 2. The first measuring method for measuring the instantaneous rainfall amount at the time of measurement from the drip time interval of the water droplets dripping through the thin tube, and the measuring means from the drip time interval of the water droplets dripping through the thin tube. The rain gauge according to claim 1, further comprising a second measurement method for determining an average amount of rainfall from the number of water droplets dropped per unit time and determining the number of water droplets dropped per unit time. 3. The rain gauge according to claim 1, wherein the measuring means has an optical sensor for detecting a time interval of water drops dripping through the thin tube. 4. The measuring means obtains the weight of a water drop from the outer diameter of the tip end surface of the thin tube and the surface tension of water, and the specific gravity of water is 1
Therefore, by converting the weight into the volume, it is possible to calculate the instantaneous rainfall by dividing the weight of the water droplet by the product of the dropping time interval of the water droplet and the area for receiving rainwater in the water collecting means. The rain gauge according to claim 1, which is characterized in that. 5. The rain gauge according to claim 4, further comprising a correcting unit that corrects the surface tension of the water according to the temperature of the rainwater flowing into the rainwater guiding unit. 6. A rainfall collecting means for collecting rainwater, a rainwater guiding means for guiding the rainwater collected by the water collecting means to a thin tube, and a rainfall amount is measured from a drip time interval of water droplets dripping through the thin tube. In a rain gauge comprising a measuring means, the thin tube has a cylindrical wall extending in the vertical direction, and a cylindrical hole extending in the vertical direction formed by the inner peripheral surface of the cylindrical wall, in water. A rain gauge, wherein a material having an affinity is contained in the hole. 7. The material is a large number of glass fibers, and the glass fibers are accommodated in the holes such that capillarity occurs between the glass fibers along the extending direction of the holes. The rain gauge according to claim 6, wherein 8. The first measuring method, wherein the measuring means measures the instantaneous rainfall amount at the time of measurement from the dropping time interval of the water droplets dripping through the thin tube, and the dropping time interval of the water droplets dripping through the thin tube. 7. The rain gauge according to claim 6, further comprising: a second measuring method for determining the average amount of rainfall from the number of water droplets dropped per unit time and determining the number of water droplets dropped per unit time. 9. The rain gauge according to claim 1, wherein the measuring means has an optical sensor for detecting a time interval of water drops dripping through the thin tube. 10. The measuring means obtains the weight of the water droplet from the outer diameter of the tip end surface of the thin tube and the surface tension of the water, and the weight of the water droplet is determined by the drop time interval of the water droplet and the rainwater in the water collecting means. 7. The rain gauge according to claim 6, wherein the instantaneous rainfall is calculated by dividing by the product of the receiving areas. 11. The rain gauge according to claim 10, further comprising a correcting unit that corrects the surface tension of the water according to the temperature of the rainwater flowing into the rainwater guiding unit. 12. A water collecting means for collecting rainwater, a water tank for storing the rainwater collected by the water collecting means, and a rainwater of the water tank which is provided so as to project downward from a bottom surface of the water tank. A thin tube and a measuring means for measuring a rainfall amount from a drip time interval of water droplets dripping through the thin tube, in which a filter member having an affinity for water is housed in the hole of the thin tube. A characteristic rain gauge. 13. The thin tube is projected downward from the bottom surface of the water tank, and the hole of the thin tube has a large diameter portion connected to the bottom surface and a small diameter formed with an inner diameter smaller than the large diameter portion. 13. The rain gauge according to claim 12, wherein the filter member is accommodated only in the large diameter portion. 14. The filter material is a large number of glass fibers having an affinity for water, and the glass fibers are accommodated in the pores by capillarity between the glass fibers along the extending direction of the pores. The rain gauge according to claim 12, characterized in that 15. The first measuring method, wherein the measuring means measures the instantaneous rainfall amount at the time of measurement from the drip time interval of the water drops dripping through the thin tube, and the drip time interval of the water drops dripping through the thin tube. 13. The rain gauge according to claim 12, further comprising: a second measuring method for determining an average amount of rainfall from the number of water droplets dropped per unit time and determining the number of water droplets dropped per unit time. 16. The rain gauge according to claim 12, wherein the measuring means has an optical sensor for detecting a time interval of water drops dripping through the thin tube. 17. The measuring means obtains the weight of the water droplet from the outer diameter of the tip end surface of the thin tube and the surface tension of the water, and the weight of the water droplet is determined by the drop time interval of the water droplet and the rainwater in the water collecting means. The rain gauge according to claim 12, wherein the instantaneous rainfall is calculated by dividing by the product of the receiving areas. 18. The rain gauge according to claim 17, further comprising a correction unit that corrects the surface tension of the water according to the temperature of the rainwater flowing into the rainwater guiding unit. 19. A water collecting means for collecting rainwater, a water tank for storing the rainwater collected by the water collecting means, and a rainwater in the water tank which is provided so as to project downward from a bottom surface of the water tank. A thin tube, and a rain gauge comprising a measuring means for measuring rainfall from a drip time interval of water droplets dripping through the thin tube, wherein a filter member having affinity for water is provided so as to cover the bottom surface of the water tank. A rain gauge characterized by 20. The rain gauge according to claim 19, wherein the filter material is a large number of glass fibers having an affinity for water. 21. The first measuring method, wherein the measuring means measures the instantaneous rainfall amount at the time of measurement from the drip time interval of the water droplets dripping through the thin tube, and the drip time interval of the water droplets dripping through the thin tube. 20. A rain gauge according to claim 19, further comprising a second measurement method for determining the average amount of rainfall from the number of water droplets dropped per unit time and determining the number of water droplets dropped per unit time. 22. The rain gauge according to claim 19, wherein the measuring means has an optical sensor for detecting a time interval of water drops dripping through the thin tube. 23. The measuring means obtains the weight of the water droplet from the outer diameter of the tip end surface of the thin tube and the surface tension of the water, and the weight of the water droplet is determined by the drop time interval of the water droplet and the rainwater in the water collecting means. 20. The rain gauge according to claim 19, wherein the instantaneous rainfall is calculated by dividing by the product of the receiving areas. 24. The rain gauge according to claim 23, further comprising a correction means for correcting the surface tension of the water according to the temperature of the rainwater flowing into the rainwater guiding means. 25. A water collecting means for collecting rainwater, a rainwater guiding means for guiding the rainwater collected by the water collecting means to a thin tube, and a drip time interval for measuring a drip time interval of water drops dripping through the thin tube. Measuring means, correcting means for correcting the surface tension of water by the temperature of the rainwater guided to the rainwater guiding means, the outer diameter of the tip surface of the thin tube, the corrected surface tension of the water, and the drip time of the water droplets. The weight measuring means for determining the weight of each water droplet from the interval and the total weight of the water droplets calculated by the weight measuring means for each unit time are calculated. Since the specific gravity of water is 1, the weight is calculated. By converting into a volume, the total amount of weight of the calculated water drops is divided by the unit time to calculate an average amount of rainfall per hour, and a rainfall amount calculating means, comprising: . 26. The rain gauge according to claim 25, wherein the measuring means has an optical sensor for detecting a time interval of water drops dripping through the thin tube. 27. A water collecting means for collecting rainwater, a rainwater guiding means for guiding the rainwater collected by the water collecting means to a thin tube, and a rainfall amount is measured from a drip time interval of water drops dripping through the thin tube. In a rain gauge equipped with measuring means, a plurality of thin tubes having different outer diameters are provided for the one rainwater guiding means, and the measuring means detects the amount of rainfall by detecting water droplets dripping from each of the thin tubes. A rain gauge characterized by making measurements. 28. The plurality of thin tubes have a first thin tube for dropping a small water drop and a second thin tube for dropping a water drop larger than the first thin tube, and the rainwater guiding means comprises: When the amount of rainwater received by the water collecting means is less than or equal to a predetermined amount, the rainwater is guided only to the first thin tube, and
The rainwater is guided to both the first thin tube and the second thin tube when the amount of rainwater received by the water collecting means exceeds a predetermined amount. 27 rain gauge. 29. The rain gauge according to claim 28, wherein the outer diameter of the first thin tube is smaller than the outer diameter of the second thin tube. 30. The rain gauge according to claim 27, wherein the amount of rainfall is measured by detecting a water drop dripping from each of the thin tubes by one measuring means. 31. The measuring means receives a plurality of light emitting elements which are provided for each thin tube and irradiate the water droplets with light whose intensity is modulated at different frequencies, and scattered light which is scattered by being radiated to the water droplets. One light receiving element and a detection that determines the water droplet of which thin tube the scattered light received by the light receiving element is based on the detection signal detected by the light receiving element, and detects the water droplet dropping time interval by distinguishing for each thin tube. 28. The rain gauge according to claim 27, further comprising: means for measuring the amount of rainfall, based on a time interval of dropping of water droplets for each thin tube detected by the detecting means. 32. The rainfall amount is measured by providing measuring means for each of the plurality of thin tubes, and measuring the drip time interval of water droplets dripping from each of the thin tubes by each measuring means. The rain gauge according to claim 27. 33. The first measuring method, wherein the measuring means measures an instantaneous rainfall amount at the time of measurement from a dropping time interval of water droplets dripping through the narrow tube, and a dropping time interval of water droplets dripping through the thin tube. 28. The rain gauge according to claim 27, further comprising: a second measuring method for determining an average amount of rainfall from the number of water droplets dropped per unit time and determining the number of water droplets dropped per unit time. 34. The rain gauge according to claim 27, wherein the measuring means has an optical sensor for detecting a time interval of water drops dripping through the thin tube. 35. The measuring means obtains the weight of the water droplet from the outer diameter of the tip surface of the thin tube and the surface tension of the water, and the weight of the water droplet is determined by the drop time interval of the water droplet and the rainwater in the water collecting means. The rain gauge according to claim 27, wherein the instantaneous rainfall is calculated by dividing the product by the product of the receiving areas. 36. The rain gauge according to claim 27, further comprising a correcting means for correcting the surface tension of the water according to the temperature of the rainwater flowing into the rainwater guiding means.