JPH0774780B2 - Rainfall snowfall discrimination sensor - Google Patents

Description

Detailed Description of the Invention

[Industrial applications]

The present invention relates to a sensor that distinguishes rain and snow using polarized light.

[Prior art]

Although it is heavenly ambition that can judge rainfall and snowfall most accurately and quickly, observation by various devices has been developed because it is not possible to observe at unmanned points and is continuously difficult. For example, a device for observing rain and snow is installed on a highway, and the weather information at the site is sent to the management place in real time. It becomes possible to inform the vehicle that is passing the information by using a sign or the like. As a device for observing rain / snow, there is a rain gauge or a device for directly determining snow / snow on a road by ultrasonic waves or electromagnetic waves to obtain information to judge rain / snow. These devices cannot judge whether it is raining or snowing until a certain period of time has passed since they started to fall. Therefore, provision of meteorological information and measures for safety management necessary for roads in the area may not be prompt. If it is possible to observe the snow before it starts to fall, it will be possible to give advance notice before the snowfall, which will greatly improve safety. There is a device using an optical sensor as a device that can be observed at the beginning of snowfall. Optical sensor devices include transmissive sensors that detect when snow blocks the optical axis from the pulsed light source, and reflective sensors that illuminate the pulsed light source in the air and reflect it on the snow to detect the reflected signal strength. Equipment.

[Problems to be Solved by the Invention]

The above-mentioned conventional device for observing rain and snow using the optical sensor has the following drawbacks. A transmission sensor device cannot detect snowfall in a strong wind parallel to the optical axis. In addition, since the reflective sensor device cannot detect rainfall, it was necessary to separately install a device for observing only rainfall. The present invention has been made to solve these drawbacks, and one device can detect the presence or absence of rainfall and snowfall, determine whether it is raining or snowing, and detect the change from rainfall to snowfall and vice versa. The present invention provides a sensor for determining rainfall and snowfall.

[Means for Solving the Problems]

A rain / snow discrimination sensor to which the present invention is applied to solve the above-mentioned problems will be described with reference to FIG. 1 corresponding to the embodiment. As shown in the figure, the rain / snow determination sensor according to the present invention is an optical system 3, 4, 6, 8 for projecting linearly polarized light 7 toward the air as an optical element, and the linearly polarized light 7 is rain or snow 9 in the air. Polarization beam splitter 12 and one light receiving lens 10 for receiving the reflected light 11 reflected by and separating it into orthogonal polarized light 13 and polarized light 14.
It has a separation optical system with. Photoelectric converters 17 and 19 for photoelectrically converting polarized light 13 and polarized light 14 as electric circuit elements
And 18, 20 and comparators 24, 25 for comparing the photoelectric conversion output e of the polarized light 13 and the photoelectric conversion output f of the polarized light 14.

[Action]

In this rain / snow discrimination sensor, the linearly polarized light 7 is projected from the optical systems 3, 4, 6, and 8 toward the air, and when it is raining, its polarization planes are almost completely reflected. When snow is falling, the polarization of the reflected light 11 scattered by the snow is disturbed and becomes the same as natural light. In the former case, since the polarization plane of the reflected light 11 is maintained, the intensity of the light traveling in the direction coincident with the polarization plane of the polarization beam splitter 12 is high, and the polarization plane of the polarization beam splitter 12 is orthogonal. Light intensity is weak. Therefore, the photoelectric conversion output e of the photoelectric converters 17 and 19 and the photoelectric conversion output f of the photoelectric converters 18 and 20 are compared by the comparator 24.
・ Comparing with 25, either one becomes stronger (e ≠ f),
It turns out that it is raining. In the latter case, since the reflected light 11 is the same as the natural light, when the polarized beam splitter 12 separates the polarized light 13 and the polarized light 14 orthogonal to each other,
The strength with 14 is equal. Therefore, when the photoelectric conversion outputs e of the photoelectric converters 17 and 19 and the photoelectric conversion outputs f of the photoelectric converters 18 and 20 are compared by the comparators 24 and 25, they are substantially equal (e≈f), and it can be seen that it is snowing.

【Example】

FIG. 1 is a block diagram of an embodiment of a rain / snow discrimination sensor to which the present invention is applied. In the figure, 1 is a pulse oscillator, 2 is a light emitting diode (LED)
Driver, 3 is a light emitting diode (LED), 4 is a focal lens, 5 is a parallel light beam, 6 is a vertically polarized beam splitter, 7
Is parallel and vertically polarized light, 8 is a projection lens, 9 is rain or snow, 10
Is a light receiving lens, 11 is a received light beam, 12 is a polarization beam splitter, 13 is a vertically polarized component, 14 is a horizontally polarized component, 15 is a vertically polarized component condenser lens, 16 is a horizontally polarized component condenser lens, and 17 is a vertically polarized light component. Diode, 18 horizontally polarized photodiode, 19 vertically polarized receiver, 20 horizontally polarized receiver, 24, 25, 26 and 27 comparators, 28 temperature sensor, 29 amplification comparator, 30 rain correlator , 31 is a snow correlator,
32 is an integrator. In the above circuit block, a pulse signal is sent from the oscillator 1 to the light emitting diode driver 2 to operate the light emitting diode 3. The light from the light emitting diode 3 is converted into parallel rays 5 by the focusing lens 4. Since the parallel rays 5 are natural light, they include all polarization components, and the vertical polarization beam splitter 6 advances only the vertical polarization components and reflects the other polarization components out of the optical path. The vertically polarized light 7 that has proceeded straight is spread by a light projecting lens 8 to an opening angle of about 10 ° and projected into a space. The projected vertically polarized light is reflected or refracted by rain or snow 9 in the space. In the case of rain, part of the vertically polarized light is reflected as it is on the smooth surface of the raindrop, and part of it is refracted to the inside of the raindrop and then refracted or reflected to the outside of the raindrop. The reflected light goes to the light receiving lens 10 where the polarized light is almost uniform. However, in the case of snow, irregular reflection on the surface near infinity causes irregular reflection, and part of it repeats refraction reflection within the crystal. Therefore, the vertically polarized light is scattered, and the light reflected toward the light receiving lens 10 has disordered polarization. The light reflected by the rain or snow 9 is collected by the light receiving lens 10 and converted into parallel light 11 and sent to the polarization beam splitter 12 for separation. Vertical polarization component in the polarization beam splitter 12 for separation
13 and horizontal polarization component 14 are separated. The vertically polarized light component 13 is focused by the condenser lens 15 and converted into an electric signal by the photodiode 17, and the vertically polarized light receiver 19 outputs the rain reflection signal e corresponding to the received light level. The horizontally polarized light component 14 is focused by the condenser lens 16 and the photodiode 18
Is converted into an electric signal by the horizontal polarization receiver 20 and the snow reflection signal f corresponding to the received light level is output. The vertical polarization receiver 19 and the horizontal polarization receiver 20 operate by the synchronization signal d from the pulse oscillator 1 so as to receive from the pulse oscillator 1 only the time and frequency for operating the light emitting diode 3, and so-called synchronous detection is performed. . When there is rainfall, the output signal e from the vertical polarization receiver 19
Is larger than the output signal f of the horizontal polarization receiver 20. The comparator 24 judges this difference and outputs an output indicating that it is raining. When it rains, the output of the vertical polarization receiver 19 and the horizontal polarization receiver 20
There is no difference in the output. The comparator 25 judges this from the respective inputs and outputs the output indicating that it is snow. On the other hand, the temperature sensor 28 measures the temperature and the amplification comparator
An internal comparison will be made between the temperature at which it rains by 29 (above 4 ° C) and the temperature at which it will snow (below 4 ° C). The output of the temperature that it rains is sent to the comparator 26, and the output of the temperature that it snows is
Sent to 27. The rain signal output from the comparator 24 is further confirmed by the comparator 26 and output as a complete rain signal a. The snow signal output from the comparator 25 is further confirmed by the comparator 27 and output as a complete snow signal b. FIG. 2 shows a time chart of (a) rain signal and (b) snow signal change of the weather change in which rain starts to turn into snow, stops, then snow again, and turns into rain. . The rain correlator 30 and the snow correlator 31 are respectively set with a rain correlation curve and a snow correlation curve as shown in FIG. These correlation curves are the results of the relationship between the intensity of the rain reflection signal and the rainfall intensity, and the relationship between the intensity of the snow reflection signal and the intensity of the snowfall, respectively, obtained from the actual measurement test. Therefore, the rain reflection signal e from the vertical polarization receiver 19 is converted into rain intensity through the rain correlator 30, and the output of the snow reflection signal f from the horizontal polarization receiver 20 is converted into snow intensity through the snow correlator 31. To be converted. These rainfall intensity and snow intensity signals are input to the integrator 32 for a fixed time (several seconds to
It is integrated for several minutes) and output as an output signal c of the rainfall and snowfall intensity. The rainfall / snow discrimination sensor according to the above-described embodiment can detect various information about rainfall / snow, and of course, since the driver 2 causes the driver 2 to emit pulsed light, the emission intensity is increased and the photodiodes 17 and 18 are detected.
The photosensitivity of is improved, and even a slight amount of rainfall and snowfall can be accurately detected. Further, the parallel and vertically polarized light 7 which is the projected light is projected by the projection lens 8
Since it is expanded to an open angle of about 10 degrees, the space capture rate is improved, and it is possible to accurately detect even when there is local rainfall or snowfall. If the opening angle is too wide, the polarized light tends to be disturbed when the reflected light from the raindrop is received. Therefore, it is necessary to keep it at an appropriate angle. If the performance of the receiver and comparator is improved, it can be used to determine sleet, fog, etc., and can also be used as a rain gauge.

【The invention's effect】

As described above, the rain / snow discrimination sensor to which the present invention is applied can continuously observe the weather condition even in an unmanned area.
It is possible to accurately and quickly detect not only the presence / absence of rainfall and snowfall but also the determination of rain or snow, the change from rainfall to snowfall, and the change from snowfall to rainfall with a single device. Therefore, it becomes possible to promptly respond to provision of weather information and measures for safety management necessary for roads in the area. In particular, the intensity can be observed when it starts to snow, and it is possible to give advance notice before snowfall, so the safety is greatly improved. Further, the rainfall / snow discrimination sensor of the present invention is provided with a photoelectric converter that receives vertically polarized light of reflected light reflected by rain and snow and a photoelectric converter that receives horizontally polarized light separately. Since the projection optical system and the light receiving optical system can be arranged adjacent to each other, since they are not discriminated from each other in the directions from the corners or more, they can be configured as an integrated device.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a rainfall / snow discrimination sensor to which the present invention is applied, FIG. 2 is a time chart diagram showing changes in a rain signal and a snow signal, and FIG. 3 is a reflection signal intensity and rainfall.
It is a correlation diagram of snowfall intensity. 1 ... Pulse oscillator, 2 ... Light emitting diode driver,
3 ... Light emitting diode 4 ... Focusing lens, 5 ... Parallel light beam, 6 ... Vertical polarization beam splitter 7 ... Parallel and vertical polarization, 8 ... Projection lens, 9 ... Rain or snow 10 ... Light receiving lens , 11 …… Received light beam, 12 …… Polarization beam splitter 13 …… Vertical polarization component, 14 …… Horizontal polarization component 15 …… Vertical polarization component condenser lens 16 …… Horizontal polarization component condenser lens, 17 …… Vertical polarization component Photodiode 18 …… Horizontal polarization photodiode, 19 …… Vertical polarization receiver 20 …… Horizontal polarization receiver, 24 ・ 25 ・ 26 ・ 27 …… Comparator 28 …… Temperature sensor, 29 …… Amplification comparator, 30 …… Rain correlator 31 …… Snow correlator, 32 …… Integrator, a …… Rain signal, b ……
Snow signal c …… output signal of rainfall snow intensity, d …… sync signal, e ……
Rain reflection signal f …… Snow reflection signal

Claims (1)

[Claims] 1. A projection optical system for projecting linearly polarized light toward the air, the linearly polarized light being received by a reflection height reflected by rain or snow in the air, and separated into two polarizations whose polarization planes are orthogonal to each other. Separation optical system having one light-receiving lens and a polarization beam splitter arranged adjacent to the projection optical system, a photoelectric converter for photoelectrically converting the two polarized lights separated by the above, and an output from the photoelectric converter A rain / snow discrimination sensor, comprising a comparator for comparing photoelectric conversion outputs of two polarized lights, and determining rain or snow by comparing the intensities of the photoelectric conversion outputs of the two polarized lights.