JPH0543997B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a weather sensor device that detects rainfall or snowfall at a desired spatial location and measures the amount of rainfall or snowfall, and particularly relates to a weather sensor device that detects rainfall or snowfall at a desired spatial location and measures the amount of rainfall or snowfall. This invention relates to a rainfall/snowfall measurement device that makes such determinations.

[Prior Art] A conventional device for determining whether it is raining or snowing uses a floodlight to project natural light onto a desired spatial position, and the light is reflected from reflective objects such as raindrops or snowflakes. There is a device that receives reflected light with a light receiver and determines whether it is raining or snowing based on the intensity of the reflected light.

In other words, when the amount of precipitation is almost the same, the intensity of reflected light from snowflakes is stronger than that from raindrops, so this difference in reflected light intensity is used to determine whether it is rain or snow. . However, with this method, for example, the intensity of reflected light in the case of heavy rain and the intensity of reflected light in the case of light snow may be the same, leading to errors in determining whether it is rain or snow.

In such a case, it may be possible to install a temperature sensor to determine that it is snow when the temperature is low. However, in the range of 0°C to 8°C, it may be rain or snow, and it is difficult to make an accurate determination.

Furthermore, instead of using reflected light, there is also a method of measuring attenuation of transmitted light. In other words, natural light is emitted from the emitter to a receiver placed a certain distance away, and when raindrops or snowflakes enter between them, the attenuation of the transmitted light is measured. Based on the strength of the attenuation, it is determined whether the light is a raindrop or a snowflake. However, with this method, if the wind blows in the direction of the light beam, snowflakes will flow in that direction, reducing the attenuation of the light. There's a problem.

Furthermore, it is possible to determine whether it is raining or snowing by observing with a television camera, but the equipment is expensive and requires constant human monitoring.

[Problems to be Solved by the Invention] As described above, in the conventional device as described above, in the device using an optical sensor, it is possible to detect whether or not there is rain or snow in the vicinity where the sensor is installed. However, it is difficult to determine whether it is raining or snowing, and when a television camera is used, the equipment is expensive and requires constant human monitoring.

The present invention was made in order to solve the above-mentioned problems in conventional devices, and aims to provide a rainfall and snowfall measuring device that can accurately determine whether it is raining or snowing.

[Means for Solving the Problems] The rain and snowfall measuring device according to the present invention uses a polarized light beam as a projected light beam, and while raindrops do not scatter the polarized plane, snowflakes are crystals and therefore scatter the polarized plane. Taking advantage of this property, we decided to determine whether it is rain or snow by measuring the scattering of the polarization plane of reflected light.

[Function] When the reflected light is separated into a vertically polarized component and a horizontally polarized component using a polarization separator, if the projected light is a vertically polarized component and a certain level of horizontally polarized component is detected, it is reflected from snow. It can be determined as a wave.

[Examples] Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, in which 1 is an electric circuit for a projector, 2 is a light source, 3 is a lens for the projector, 4 is a polarizer, 5 is a projected light beam, and 6 is a reflective object, 7 is a reflected light, 8
9 is a light receiving lens, 9 is a polarization separator, 10 is a vertical light receiving element, 11 is a horizontal light receiving element, 12 is a vertical receiver, 13 is a horizontal receiver, 14 is a signal processing section, and 8 to 13 are the light receiving device. It is configured.

A polarized light beam 5 is projected onto a reflecting object 6
The reflected light 7 from
The vertically polarized light component is converted into an electrical signal by the vertical light receiving element 10, and the horizontally polarized light component is converted into an electrical signal by the horizontal light receiving element 11.

The outputs of the vertical light receiving element 10 and the horizontal light receiving element 11 are amplified by a vertical receiver 12 and a horizontal receiver 13, respectively, and input to a signal processing section 14. The signal processing section 14 processes the output of the vertical receiver 12 and the output of the horizontal receiver 13 to determine the nature of the reflecting object.

For example, the output of the horizontal receiver 13 is the output of the vertical receiver 12.
When the output is sufficiently small compared to the output of , it means that no scattering of the plane of polarization occurs in the reflecting object 6, and therefore, it is determined that the reflecting object 6 is not snow.

2 to 5 are diagrams for explaining the principle of this invention, and in these figures, the same reference numerals as in FIG. 1 indicate the same or corresponding parts, and 1
5 is raindrop, 24 is ice grain, 33 is snowflake, 16, 19
are incident light (light beam 5, here, incident light on a reflective object), respectively. 17,30
are reflected light, 18, 20, 21, 25, 2, respectively.
6, 31, 32 are refracted lights, 22, 27,
28 and 34 each represent a polarized wavefront.

As shown in FIG. 2, the incident light 16 having the polarized wavefront 22 that is incident on the point A of the raindrop 15 becomes reflected light 17 corresponding to the angle of incidence. This is the same as the polarization wavefront 22.

The polarized wavefront of the refracted light 18 that is refracted into the raindrop 15 at point A, refracted at point B, and exits from the raindrop 15 is also the same polarized light as the incident light 16 because the raindrop 15 is water and is an isotropic substance. It has a wave front 22.

Incident light 19 is refracted light 2 refracted at point C and point D.
0, and becomes refracted light 21 that is reflected at point D, refracted at point E, and emitted, but these refracted lights 2
The polarization wavefronts of 0 and 21 are also similar to the polarization wavefront 22 of the incident light 19 because water is an isotropic substance as described above.

As described above, when the reflective object is a raindrop 15 and the incident light has a vertically polarized component, the catadioptric light does not include a horizontally polarized component.

Next, as shown in FIG. 3, it is assumed that the light beam 5 having the polarized wavefront 27 is incident on the point F of the ice grain 24. The ice grains 24 are hexagonal crystals, and incident light causes birefringence. In other words, the refractive index for light that is refracted while maintaining the same polarized wavefront as the incident light, that is, the refractive index of ordinary rays, is 1.309, and the refractive index for light that is refracted with a polarized wavefront that is different from the incident light,
In other words, the refractive index of the extraordinary ray is 1.313 (when the temperature of the ice grains 24 is 0°C), so the polarization wavefront 2
7 and the refracted light 26 having a polarization wavefront 28 have different traveling directions.

Therefore, as shown in FIG. 4, the reflected light 30 reflected at point F of the ice grain 24 is kept at the same polarization wavefront as the incident light 5, and the refracted light 32 refracted as an ordinary ray at point F is H Although the refracted light 32 is refracted at a point and emitted from the ice grain 24, this refracted light 32 has the same polarization wavefront as the incident light 5. However, although the refracted light 31 refracted as an extraordinary ray at point F is refracted at point G and exits from the ice grain 24, the polarized wavefront of this refracted light 31 is different from the polarized wavefront of the incident light 5.

Furthermore, as shown in FIG. 5, the snowflake 33 is
The incident light having a polarized wavefront 27 is reflected and refracted many times in the snowflake 33, and is reflected by the light receiving lens 8 shown in FIG. The polarization wavefront of the reflected light 7 that enters is
As shown at 34 in FIG. 5, it becomes almost random.

Reflected light 7 of such a random polarized wavefront 34
can be separated into a vertically polarized component and a horizontally polarized component. Therefore, if the projected light beam 5 is set as a vertically polarized component, if the reflected light 7 does not include a horizontally polarized component, it is rain, and horizontally polarized light is detected. When it contains more than a certain amount of ingredients, it can be determined as snow.

Further, depending on the strength of the horizontally polarized component included in the reflected light 7, it is possible to determine whether it is sleet, wet snow, dry snow, or the like.

[Effects of the Invention] As explained above, in this invention, the projected light beam is a polarized light beam and the scattering of the polarization plane of the reflected light is measured, so it is possible to accurately determine whether it is rain or snow. This method has the advantage of being able to determine whether it is sleet, wet snow, dry snow, etc.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the invention, and FIGS. 2 to 5 are diagrams for explaining the principle of the invention. 1... Electric circuit for floodlight, 2... Light source, 3...
Lens for projector, 4...Polarizer, 5...Light beam (incident light), 6...Reflecting object, 7...Reflected light, 8...
...Receiver lens, 9...Polarization separator, 10...
Vertical light receiving element, 11... Horizontal light receiving element, 12... Vertical receiver, 13... Horizontal receiver, 14... Signal processing section. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A light projector that projects a light beam polarized to a predetermined polarization wavefront into the air. A light receiver that receives reflected light from a light beam projected from this light beam reflected by reflective objects such as raindrops and snowflakes present in the light beam; a polarization separator that separates the light into a vertically polarized component and a horizontally polarized component; a first light-receiving element that outputs an electrical signal that depends on the strength of the vertically polarized component separated by the polarization separator; a second light-receiving element that outputs an electrical signal that depends on the strength of the separated horizontally polarized light component; A rainfall and snowfall measurement device comprising: a signal processing unit that determines the type of the reflecting object based on the difference.