JPH0423740B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method and apparatus for measuring the intensity of rainfall or snowfall separately by optical means in meteorological observation work. .

[Conventional technology]

A conventional method for measuring rainfall or snowfall intensity is known by measuring the amount of rain or snowfall over a set length of time. In addition, rain and snow discrimination is usually performed separately from intensity measurement.
This rain/snow discrimination method involves, for example, placing a pair (two sheets) of conductive plates in the air electrically separated from each other by creating a small gap between them, and placing the pair of conductive plates in the gap as a bridge. A known method is to measure the electrical conductivity of raindrops or snowflakes that have fallen on each other, and to discriminate based on the difference in electrical conductivity.

[Problems that the invention attempts to solve]

The conventional rainfall or snowfall intensity measurement method described above basically measures the amount of rainfall or snowfall, so it can only obtain past data going back to the set time from the current moment, and the instantaneous rainfall or snowfall intensity at the present moment can only be obtained. It is difficult to obtain.

Further, when it is necessary to measure the intensity of rainfall and snowfall separately, it is necessary to measure the intensity and distinguish between rain and snow using separate measuring means, which makes the measuring device large and complicated. In addition, since rain and snow discrimination in this case is based on contact means, there may be a delay in determining whether it is snowfall due to melting of snowflakes, or raindrops or snowflakes may be caused by gaps between the conductive plates during drizzle or powdery snow. At present, it is difficult to measure the instantaneous intensity of rainfall and snowfall due to delays in determining rain or snowfall due to finer details, and furthermore, rain/snow discrimination means in principle require electrical contact surfaces (conductive plates) to be placed in the air. Since it is necessary to expose the electrical contact surface to air, there are problems such as the initial performance cannot be maintained for a long period of time due to dirt, corrosion, etc. on the electrical contact surface.

The present invention is proposed to solve the above-mentioned conventional problems, and is capable of instantly grasping the rainfall or snowfall intensity at the present time without having to look back into the past, and also capable of simultaneously distinguishing between rain and snowfall. The purpose is to obtain a measurement method and device.

[Means for solving problems]

In order to solve the above problems, the present invention provides that, when light is projected onto raindrops or snowflakes, the number and level of reflected pulses reflected from the raindrops or snowflakes are proportional to the falling density of the raindrops or snowflakes. Focusing on the fact that light exhibits a certain correlation between snowflakes and raindrops, and that the diffusion direction characteristics of light differ from each other when light is projected onto snowflakes or raindrops, we projected light into space and analyzed the effects of raindrops or snowflakes from the projected light. A method of receiving reflected light pulses, calculating the intensity of rain or snowfall from the number and level of the received light pulses, and determining whether it is rain or snow based on the level of the received light pulses, thereby measuring the intensity of each rain or snowfall. Further, as a rain/snowfall intensity measuring device using this method, the present invention provides a light projecting means for projecting light into space, and an optical axis having a different angle with respect to the optical axis of the light projecting means. first and second light receiving means respectively set in directions intersecting with each other and receiving reflected light pulses obtained by reflecting the projected light from the light projecting means on raindrops or snowflakes;
a counting means for measuring the number of light pulses received by the light receiving means; a level measuring means for measuring the level of the light receiving pulse; a level comparing means for comparing the levels of both of the light receiving pulses; A rainfall/snowfall intensity measuring device comprising a calculation means for calculating the intensity of rainfall and snowfall based on the output information respectively output from the means and the level comparison means, or a single light receiving means instead of the above two light receiving means, and a polarizing means set in the path of the light,
The calculating means provides a rainfall/snowfall intensity measuring device which calculates the intensity of rain and snowfall separately from the number and level of light pulses received by the light receiving means.

[Configuration of Example]

1 and 2 are block diagrams showing first and second embodiments of the present invention, respectively.

First, the configuration of the first embodiment will be explained.

In Figure 1, 1 is a floodlight, 2 is a driver,
3 is a first light receiver, 4 is a second light receiver, 5 and 6 are amplifiers, 7 and 8 are synchronous detectors, 9 is a level detector, 10 is a level comparator, 11 is a pulse counter,
12 is a computing unit, a indicates the optical axis of the projector 1, and b
indicates the optical axis of the first photodetector 3, c indicates the optical axis of the second photodetector 4, and d indicates the intersection of optical times a, b, and c, respectively.

The light projector 1 projects light into space, and includes a light emitting element, a light projecting optical lens, and the like.

The driver 2 drives the light emitting element of the floodlight 1 to emit light, and includes a light emitting power supply section, a modulation section that modulates the output power from the light emitting power supply section, and a driver 2 that controls the light emission intensity of the light emitting element according to changes in environmental conditions such as temperature. It consists of an automatic power control section, etc., which controls the output power from the light emitting power supply section to keep it constant regardless of the lighting conditions.

The first light receiver 3 and the second light receiver 4 each receive the reflected light pulse of the light projected from the light projector 1 on raindrops or snowflakes, and output a light reception pulse signal (electrical signal) corresponding to the received light intensity. The first light receiver 3 and the second light receiver 4 each include a light receiving optical lens and a light receiving element, and the optical axes b and c of the first light receiver 3 and the second light receiver 4 are at an angle θ _{1 and an angle θ 2 with} respect to the optical axis a of the projector 1, respectively. (θ ₁ ≠θ ₂ ), and ideally the respective pointing directions are set so that they intersect at the same intersection d.

The amplifier 5 and the amplifier 6 amplify the light reception signals output from the first light receiver 3 and the second light receiver 4, respectively.

The synchronous detector 7 and the synchronous detector 8 are connected to the first optical receiver 3 and the second optical receiver via the amplifier 5 and the amplifier 6, respectively.
It detects the light reception signal inputted from the light receiver 4, synchronously detects the light reception signal with the modulation signal of the light emitted from the light projector 1, and outputs a pulse signal with a level proportional to the intensity of the light reception signal.

The level detector 9 detects the average level of the level signals output from the synchronous detectors 7 and 8.

The level comparator 10 compares the level of the pulse signal output from the synchronous detector 7 and the level of the pulse signal output from the synchronous detector 8.

The pulse counter 11 counts the received light pulse signals outputted via the synchronous detectors 7 and 8.

The calculator 12 calculates the output information outputted from the level detector 9, the level comparator 10, and the pulse counter 11 by comparing it with the data inputted in advance, and calculates the intensity of rain or snowfall. /It detects snowfall and consists of a microprocessor (CPU) and a rain/snow detection and intensity calculation program installed in it.

In the first embodiment, the level detector 9 and the pulse counter 10 are for measuring the intensity of rainfall and snowfall, the level comparator 10 is for distinguishing between rain and snow,
The other parts are shared by rainfall and snowfall intensity measurement and rain/snow detection. However, one of the two light receiving systems is functionally provided for determining whether it is rain or snow.

Next, the configuration of the second embodiment will be explained.

In FIG. 2, 13 is a polarizing means, and other symbols are the same as those in the first embodiment (FIG. 1). However, since the second embodiment has one light receiving system, the symbol of the first light receiving system (the system to which the first light receiver 3 belongs) of the first embodiment is used as the symbol of the light receiving system.

The polarizing means 13 is configured to pass only, for example, a horizontal wave of the reflected light in a direction at an angle θ from the optical axis a of the projector 1 at the intersection d, and is formed of, for example, an optical polarizing filter.

The functions other than those described above are the same as those of the corresponding symbols in the first embodiment.

In the second embodiment, the pulse counter 11 is used to measure the intensity of rainfall and snowfall, and the other parts are commonly used to measure the intensity of rain and snowfall and to discriminate between rain and snow. However, the polarizing means (polarizing filter 13
Functionally, it is provided to distinguish between rain and snow.

[Effect of the embodiment]

First, the operation of the first embodiment will be explained.

The driver 2 constantly outputs a drive signal for driving the light emitting element in the projector 1 to emit light. This drive signal is a modulated signal, and its output power is controlled by environmental conditions such as temperature. Therefore, the floodlight 1 always emits modulated light whose emission intensity is always constant. It is projecting. The first receiver 3 and the second receiver modulate the projected light.
This is to distinguish between regular reflected light and backlight when the light receiver 4 receives reflected light, and to be sensitive to only regular reflected light.

When there is no rain or snow, there is no reflection of the light projected from the projector 1 (in reality, there is reflection from dust floating in the air, but this reflection is caused by raindrops or snowflakes within a small and limited measurement area). ), the first light receiver 3 and the second light receiver 4 do not sense the reflected light.

When it rains or snows, the light projected from the projector 1 travels straight along the optical axis a, is reflected by raindrops or snowflakes descending at the intersection d, and is transmitted to the first receiver 3 and the second receiver 3.
The reflected light is incident on the light receiver 4 in the form of a pulse.

The first light receiver 3 or the second light receiver 4 outputs an electric signal (pulse signal) proportional to the intensity of the reflected light in response to the reflected light, and after this signal is amplified by the amplifier 5 or 6, The signal is synchronously detected by the synchronous detector 7 or 8. The synchronous detector 7 and the synchronous detector 8 output pulse signals at a level proportional to the intensity of the reflected light pulses that have entered the first optical receiver 3 and the second optical receiver 4, respectively. The pulse signals output from the synchronous detector 7 and the synchronous detector 8 are input to the level detector 9 and added, and the average level of the pulse signals is calculated.The pulse signals are also input to the level comparator 10 for level comparison. will be carried out.

Further, the number of reflected light pulses that enter the first photoreceiver 3 and the second photoreceiver 4 is counted at any point, but in this embodiment, the pulse counter 11 is connected to the output terminal of the level comparator 10. The output terminal is used as a counting point for reflected light pulses. The reason why the output terminal of the level comparator 10 is used as the counting point is that, as will be described later, the output terminal has the output signal level of one synchronous detector 7 as the sum of the output signal levels of both synchronous detectors 7 and 8. Since the signal divided by For example, even reflected light pulses with a low level of incidence on the light receiver are counted without being omitted.)

As described above, the level information of the reflected light pulse output from the level detector 9, the level comparator 1
Receiving the level comparison information of the reflected light pulses from two different directions output from the pulse counter 11 and the count information of the reflected light pulses output from the pulse counter 11, the calculator 12 determines whether it is raining or snowing and determines whether it is raining or snowing. Perform strength calculations.

Next, it will be explained that rain/snow discrimination and intensity calculation are possible using the above three types of output information.

First, regarding rain and snow discrimination, the two light receivers 3 and 4 are used in the case of rain and snow.
The received light level ratio of the reflected light pulses differs markedly. That is, as shown in FIG. 3A, raindrops fall in a specific shape because they are amorphous liquids, and the light diffusion characteristics of the raindrops of projected light from one direction are determined by the direction of the characteristics. It is a characteristic that has a local minimum point and a local maximum point. On the other hand, as shown in Figure 3B,
Since snowflakes are crystalline solids and fall while rotating, if observed over a period of time, they fall in a shape that is almost equivalent to a sphere, and the light diffusion properties of the snowflakes are similar to those of raindrops. The characteristic does not have such minimum and maximum points.

Therefore, if the optical axis b of the first light receiver 3 and the optical axis c of the second light receiver 4 are set in different directions, that is, the respective optical axes b or c are aligned with the optical axis a of the projector 1. If the angles θ ₁ and θ ₂ are different from each other, the ratio between the incident intensity of the reflected light on the first receiver 3 and the incident intensity of the reflected light on the second receiver 4 will be different during rain and snow. This difference in incident intensity can be detected by comparing the levels of the output pulse signals from the synchronous detectors 7 and 8.

The angle θ ₁ between the optical axis b and the optical axis a is set to a size that approaches the maximum point of the light diffusion level distribution characteristics due to raindrops, and the angle θ ₂ between the optical axis c and the optical axis a is set to a value that is as close as possible to the maximum point of the light diffusion level distribution characteristics due to raindrops. It is desirable to set each to a size as close as possible to the minimum point of the characteristic. That is, in the level comparison operation in the level comparator 10, the larger the difference in level between the two, the easier the comparison.

The level comparison by the level comparator 10 is based on the output level of the first light receiving system (output level of the synchronous detector 7).
Letting l ₁ be the output level of the second light receiving system (output level of the synchronous detector 8) as l ₂ , this is performed, for example, by calculating the following equation: K=l ₁ /l ₁ +l ₂ . As is clear from FIG. 3A or B, the value of K becomes larger when it is raining than when it is snowing. Therefore, by comparing and calculating the output information from the level comparator 10 with a set value in the calculator 12, it is possible to determine whether it is raining or snowing.

Next, regarding the measurement of the intensity of rain or snowfall, the number and level of reflected light pulses incident on the first light receiver 3 and the second light receiver 4 have a correlation with the intensity of rain or snowfall. This correlation is shown in FIG.

Figure 4 is a graph based on empirical data on rainfall and snowfall intensity.Although the number of pulses is the same and the intensity at the same level is different in the case of rain and snowfall, the tendency of change (gradient of characteristics, etc.) is different for both cases. Both are almost the same.

As is clear from FIG. 4, even if the number of reflected light pulses is the same, the higher the level, the greater the intensity of rainfall or snowfall. This is understood because the larger the particles of raindrops or snowflakes, the more of the projected light is reflected.

The data shown in FIG. 4 is input into the calculator 12 in advance as a calculation processing map, and therefore the level information (la, lb, lc...) from the level detector 9,
Based on the count information N from the pulse counter 11, the calculator 12 calculates the intensity of rainfall or snowfall and outputs intensity data.

Also. The intensity data is output separately for rain and snow based on the rain and snow determination data.

Next, the operation of the second embodiment will be explained.

In the second embodiment, there is only one light receiving system, and a polarizing means, for example, an optical polarizing filter 11 is provided on the light traveling path, for example, on the optical axis b in front of the light receiving surface of the light receiver 3. This is different from the first embodiment in this point. This difference is related to the rain/snow discrimination operation, and the intensity measurement operation is performed in the same manner as in the first embodiment.

Rain/snow discrimination in the second embodiment will be explained.

Observing the light reflected by raindrops or snowflakes,
In the case of raindrops, the light is polarized and reflected in a specific direction as shown in Figure 5A, but in the case of snowflakes, the light is reflected in the 5th direction.
It is reflected in all directions as shown in Figure B. This is because a mirror surface is formed on the surface of a raindrop and the projected light is strongly reflected in a specific direction, whereas a mirror surface is not formed on the surface of a snowflake and the projected light is diffusely reflected.

Therefore, if the direction of the polarization plane of the polarizing filter 13 is set perpendicular to the polarizing direction of the light reflected by raindrops, the amount of reflected light that passes through the polarizing filter 13 is small in the case of rain (low transmittance); It increases (transmittance is high) in the case of snowfall.

As a result of the above, the level of the signal output from the synchronous detector 7 is low when it is raining, and high when it is snowing. Therefore the level detector 12
By detecting the level of the output signal of the synchronous detector 7 and performing calculations in the arithmetic unit 10 based on this level information, it is possible to determine whether it is raining or snowing.

The intensity of rainfall or snowfall in the second embodiment can be determined by counting received pulses of reflected light output from the synchronous detector 7 using a pulse counter 11 to obtain count information, and level information output from the level detector 9. The calculated value is also input to the calculator 12, and the calculator 12 calculates the rainfall or snowfall intensity in the same manner as in the first embodiment.

Incidentally, the setting position of the polarizing filter 13 may be in front of the light projection surface of the light projector 1. That is, by polarizing the projected light in a specific direction, the amount of reflection from snowflakes can be increased compared to the amount of reflection from raindrops.

〔Effect of the invention〕

As explained above in detail, the present invention grasps the reflected light pulse of the projected light by raindrops or snowflakes,
Rainfall, based on the number of reflected light pulses and the level of received light.
It provides a method or device that measures the intensity of each type of snowfall, and not only can the current intensity of rainfall or snowfall be determined instantly regardless of the degree of rainfall or snowfall, but also can be used to measure the intensity of each part of the device. Since most of the information can be used for rain/snow discrimination and intensity measurement, the device configuration is simple, and there is no need for electrical circuits that are exposed to the air (outside air), so the initial characteristics can be maintained over a long period of time. The present invention has extremely significant effects, such as being able to maintain the following properties.

[Brief explanation of drawings]

1 and 2 are block diagrams showing a first embodiment and a second embodiment of the present invention, respectively, and FIG. 3A,
B, FIG. 4, and FIGS. 5A and 5B are diagrams for explaining the measurement principle of the first embodiment and the second embodiment, respectively. 1... Emitter, 3, 4... Receiver, 7, 8...
Synchronous detector, 9... Level detector, 10... Level comparator, 11... Pulse counter, 12... Arithmetic unit, 13... Polarizing means (polarizing filter).

Claims (1)

[Claims] 1. Project light into space, receive reflected light pulses of the projected light from raindrops or snowflakes, measure the number and level of the received light pulses, and calculate the difference in the level of the received light pulses. In addition to determining whether it is rain or snow,
An optical rainfall/snowfall intensity measuring method that calculates the intensity of rainfall or snowfall based on the number and level of the received light pulses, and measures the intensity of each rainfall and snowfall. 2. A light projecting means for projecting light into space, the optical axes of which are set in directions that intersect at different angles with respect to the optical axis of the light projecting means, and the projected light from the light projecting means is a first light receiving means and a second light receiving means for respectively receiving reflected light pulses reflected by snowflakes; a counting means for measuring the number of light pulses received by the first light receiving means and the second light receiving means; Level measuring means for measuring the level of the received light pulse;
An optical system comprising a level comparing means for comparing the levels of both of the received light pulses, and a calculating means for calculating the intensity of rain and snowfall separately based on the output information output from the counting means, the level measuring means and the level comparing means, respectively. Rainfall/snowfall intensity measuring device. 3. A light projecting means for projecting light into space, a light receiving means for receiving reflected light pulses obtained by reflecting the projected light from the light projecting means on raindrops or snowflakes, and a light receiving means in front of the light projecting surface of the light projecting means or the above light receiving means. polarizing means provided in front of the light-receiving surface of the light-receiving surface so that the light-transmitting surface intersects with the optical axis; a counting means for measuring the number of light pulses received by the light-receiving means; and a level measurement means for measuring the level of the light-receiving pulses. an optical rainfall/snowfall intensity measuring device comprising: means; and calculating means for calculating the intensity of rainfall and snowfall separately based on output information respectively output from the counting means and the level measuring means.