JP2001216592A - Road surface state detector of road - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a road surface state detector of a road capable of detecting the state of an area to be detected by deciding the presence/absence of a matter to be detected in the area to be detected on the road surface of the road stably without receiving influence from external light without regard to a day or night. SOLUTION: The road surface detector 1 is basically provided with a light irradiating means 5, a photodetecting means 6, an arithmetic judging means 7, a communication means 8 and a control means 9, successively switches irradiating light 3 comprising detecting light 3a having a specific wavelength concerning a matter to be detected A set in advance and reference light 3b to irradiate the area to be detected R on the road surface 2a of the road 2 with it, successively receives reflected light 4 obtained by reflecting the light 3 in the area R in synchronization with switching of the light 3 to convert it to an electric information to compare and calculate, and decides the presence/absence of the matter A in the area R to detect the state of the area R.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection device for detecting the presence or absence of an object in a detection area on a road surface of a road and detecting the state of the road surface. It relates to a preferred sensing device.

[0002]

2. Description of the Related Art When a road surface freezes, it hinders traffic of vehicles and pedestrians, and easily causes traffic accidents. In addition, such freezing makes it easier for snow to accumulate, and furthermore to cause accidents.

[0003] Regarding freezing of the road surface, in recent years, the road has been heated by a heating wire or a heating sheet buried in the road in advance to prevent the road from being frozen. In this case, even when the road surface temperature is high and the road surface is not likely to freeze, energizing the heating wire or the heating sheet results in wasteful power consumption, which is not preferable in terms of energy saving and increases the cost. It is desirable to detect whether or not the road surface is frozen, and to energize the heating wire or the heating sheet only when the road surface is detected to prevent the road surface from being frozen.

[0004] As means for detecting road surface conditions such as freezing, snow cover, wetness and dryness, it is known to install a detecting device for measuring the temperature of the road surface on the road. Examples of such a detection device include a fixed point sensor for detecting the temperature such as an infrared thermometer and a thermocouple, and a fixed point sensor for detecting the amount of moisture such as an electrode-type middle road surface moisture meter and a road surface reflection ratio meter.

[0005] Further, there is known a road surface condition detecting device 51 which is simplified as shown in FIG. The road surface state detecting device 51 includes an imaging unit 53 installed at an appropriate height beside the road 52, a fixed point sensor 54 installed on the road surface 52a, and a control unit that controls the imaging unit 53 and the fixed point sensor 54. 55. The imaging unit 53 is realized by, for example, a visible light camera, and images the road surface 52a.
The fixed point sensor 54 is a fixed point setting sensor realized by the infrared thermometer, the thermocouple, the electrode-type road surface moisture meter, the road surface reflection ratio meter, and the like. The fixed point sensor 54 detects the temperature at the position where the fixed point sensor 54 of the road surface 52a is installed. And / or detecting the water content. The control unit 55 is housed in a housing separate from the imaging unit 53 and is installed near the road 52. Further, the control means 55 further includes a communication means for transmitting the image of the road surface 52 a by the imaging means 53 and the data of the temperature and / or moisture content by the fixed point sensor 54 to the monitoring center 56.

The monitoring center 56 includes, for example, the road surface 5
There is an observer for monitoring the condition of the road 2a, and the observer reads the image of the road surface 52a and the data of the temperature and / or moisture content of the road surface 52a sent to the monitoring center 56 via the communication means. Based on this, it is determined whether or not the road surface 52a is frozen. At this time, for example, when the monitor determines that the road surface 52a is frozen, the thawing of the road surface 52a is started by, for example, energizing a heating line or a heating sheet (not shown) embedded in the road 52 in advance.

Further, as shown in a simplified block diagram of FIG. 9, there is known a road surface condition detecting device 61 in which a control means 62 includes an image processing means 63 and a calculation judging means 64. Such a road surface state detecting device 61 basically includes an image pickup means 65 installed at an appropriate height beside a road and a road surface state detecting device, similarly to the road surface state detecting device 51 shown in FIG. A fixed point sensor 66 and a control means 62 for controlling the imaging means 65 and the fixed point sensor 66 are provided. The imaging means 65 is, for example, a visible light CCD (Ch
(Arch Coupled Device) camera or the like. As the fixed point sensor 66, for example, the same fixed point setting sensor as described above is used. The control unit 62 includes the image processing unit 63 and the operation determination unit 64 as described above, is housed in a housing separate from the imaging unit 65, and is installed near the road surface.

[0008] The road surface image picked up by the image pick-up means 65 is subjected to image processing such as, for example, binarization processing in the image processing means 63, and sent to the arithmetic determination means 64. The data of the road surface temperature and / or the amount of moisture detected by the fixed point sensor 66 are also sent to the calculation judging means 64. The arithmetic determination unit 64 performs an arithmetic process based on the above-described image-processed road surface image and road surface temperature and / or moisture content data, and automatically determines whether the road surface is frozen. . Further, the control means 62 further includes a communication means for sending the result of the determination by the calculation determining means 64 to the monitoring center 67. If the calculation determining means 64 determines that the road surface is frozen, the control means 62 is at the monitoring center 67. By a watcher or by a monitoring center 67
For example, the road surface is prevented from freezing by automatically energizing a heating line or a heating sheet embedded in the road in advance.

However, in such road surface condition detecting devices 51 and 61, since the images obtained by the image pickup means 53 and 65 are significantly different between day and night, it is difficult to make an accurate determination.
It is difficult to detect the state of the road surface. Further, the road surface state detecting devices 51 and 61 are easily affected by extraneous light, and even if the road surface in the same state is imaged by the road surface imaging means 53 and 65, the obtained images may be significantly different. Is easy to mistakenly detect. The imaging means 53 and 65 are also significantly affected by weather such as snowstorm.

As described above, these road surface condition detecting devices 5
In Nos. 1 and 61, it is difficult to detect whether water or ice is present on the road surface only by the images obtained by the imaging means 53 and 65, and furthermore, a fixed point for detecting the temperature and / or the moisture content of the road surface. It was necessary to use the sensors 54 and 66 together to comprehensively detect whether the road surface was water or ice from the image and these data. However, the fixed point sensors 54 and 66 can be installed only at fixed points,
In order to detect a wider area of the road surface, it is necessary to install more fixed point sensors. Providing a large number of fixed point sensors makes it difficult to install the detection device itself, such as complicated electrical connection, and has the disadvantage of increasing the cost.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to stably cover a road surface regardless of day and night and without being affected by extraneous light. It is possible to determine the presence or absence of an object in the detection area and detect the state of the area to be detected, and furthermore, when the object to be detected is ice and water, whether ice is present on the road surface. An object of the present invention is to provide a road surface condition detecting device capable of detecting whether the surface is water or not, and detecting road surface conditions such as freezing, wetness, and dryness of the road surface.

[0012]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, successively switching two or more types of light having a specific wavelength with respect to a predetermined object to be detected. By irradiating the area to be detected on the road surface of the road and converting the irradiating light reflected from the area to be detected into an electric signal and performing a comparison operation, it is stable regardless of day and night and without being affected by extraneous light. The presence or absence of an object to be detected in the detected area to detect the state of the detected area, and when the detected object is ice and water, ice is on the road surface. The present inventors have found that it is possible to easily determine whether the road surface is water or water and detect road surface conditions such as freezing, wetness, and dryness of the road surface, and have completed the present invention.

That is, the present invention is as follows. (1) having a transmission optical system and a wavelength variable laser device,
Irradiation light of two or more wavelengths containing detection light having the same wavelength as the absorption wavelength of the object to be detected in advance and reference light having a wavelength close to the detection light and hardly absorbed by the object to be detected. Having a light irradiating means for sequentially switching and irradiating a detected area on the road surface of the road, a receiving optical system and a light receiver,
A light receiving means for sequentially receiving the reflected light reflected from the detected area by the light irradiating means from the detected area and converting the reflected light into an electric signal in synchronization with switching of the irradiation light of the light irradiating means; A comparison operation is performed between the electric signal of the reflected light of the detected light and the electric signal of the reflected light of the reference light to calculate the presence / absence of an object in the detection area. Road surface state detection of a road characterized by detecting a state of a detected area, comprising: communication means capable of remotely communicating the determination result; and light control means for controlling the light irradiation means, light receiving means, calculation determination means and communication means. apparatus. (2) The road surface condition detecting device according to (1), wherein the detection light and the reference light are both infrared light. (3) the detection object is ice and water, the detection light is a first detection light having the same wavelength as the absorption wavelength of ice;
A second detection light having the same wavelength as the absorption wavelength of water, wherein the reference light has a wavelength close to the first detection light and is hardly absorbed by ice; A second reference light having a wavelength close to the second detection light and hardly absorbed by water, containing one or more lights having the same or different wavelengths; The electric signal of the reflected light of the detection light is compared with the electric signal of the reflected light of the first reference light, and the electric signal of the reflected light of the second detection light and the electric signal of the reflected light of the second reference light are calculated. (1) or (2), wherein the presence or absence of ice and water in the detected area is determined by comparing and calculating the freezing, wetting and drying of the detected area. Road surface condition detection device. (4) The road is provided with road surface freezing prevention means for starting prevention of road surface freezing when receiving at least a determination result that the road surface is frozen transmitted by the communication means. The road surface condition detecting device for roads according to (1).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
FIG. 1 is a simplified block diagram showing a preferred example of the road surface condition detecting device 1 of the present invention, and FIG. 2 is a diagram schematically showing a preferred installation example of the road condition detecting device 1 of the present invention. The road surface condition detecting device 1 of the present invention sequentially switches two or more types of irradiation light 3 having a specific wavelength with respect to an object A to be detected, and irradiates the object region R with the irradiation light 3. The reflected light 4 reflected by the region R is sequentially received in synchronization with the switching of the irradiation of the irradiation light 3, and the reflected light 4 is converted into an electric signal to perform a comparison operation. This is a detection device that determines whether or not the detection area R is present and detects the state of the detection area R. Here, the detection region R is one region of the road surface 2a of the road 2, and the detection object A is preferably ice, and more preferably ice and water. The road surface state detecting device 1 of the present invention includes:
It is suitable as a road surface condition sensor for detecting road surface conditions such as freezing, wetness, and dryness of the road surface, and is particularly suitable as a road surface freezing sensor for detecting freezing of the road surface 2a.

As shown in FIG. 1, a road surface condition detecting device 1 of the present invention basically comprises a light irradiating means 5 and a light receiving means 6.
, An operation determination unit 7, a communication unit 8, and a control unit 9. The light irradiating means 5 has a wavelength variable laser device 10 and a transmission optical system 11. Tunable laser device 10
Is a laser device having wavelength variable means, which can sequentially switch and emit laser beams of at least two or more wavelengths. The laser light having two or more wavelengths passes through the transmission optical system 11 and becomes the irradiation light 3 on the road surface 2.
A is sequentially irradiated to the detection region R of FIG. The irradiation light 3 emitted from such light irradiation means 5 is sequentially switched at least two or more, preferably three or more, and more preferably four or more wavelengths.

The irradiation light 3 includes a detection light 3a having the same wavelength as a predetermined absorption wavelength of the detection target A, and the detection light 3a.
Reference light 3b having a wavelength close to a and hardly absorbed by the detection object A.

The irradiation light 3 emitted from the light irradiation means 5 is 1
Assuming that only the seeds are present, for example, if the irradiation light 3 is only the detection light 3a, the reflected light intensities of the detection light 3a in the case where the detection object A is present in the detection region R and the case where the detection object A is not present are compared. Thus, it is possible in principle to determine the presence or absence of the detection target A in the detection target region R. However, this is easily affected by the degree of light reflection (reflectance) due to the difference in the material of the detection region R and / or the surrounding environment such as climate, and the state of the detection region R cannot always be accurately detected. .

The wavelength tunable laser device 10 used in the present invention is not particularly limited as long as it is a laser device capable of sequentially switching and emitting laser beams of at least two or more wavelengths. This is realized by a laser device including the used optical parametric oscillator.

When the wavelength tunable laser device 10 is realized by a laser device having an optical parametric oscillator,
It has a fundamental wave oscillation means and a wavelength variable means. The fundamental wave oscillating means includes a light emitting unit and a resonator provided so as to sandwich the light emitting unit so that laser light can be oscillated. Such a fundamental wave oscillating means may be realized by a known or practiced one in the field of a conventional laser, and the light emitting unit may include, for example, a laser active medium which emits light when excited by an external excitation light. It is realized to have. As such a laser active medium, a solid laser crystal, a laser gas, a semiconductor crystal and the like are preferable, and a solid laser crystal is particularly preferable. Further, the fundamental wave oscillating means may be realized to include a semiconductor light emitting element as an exciting means configured to allow current injection. As such a semiconductor light emitting element, an LD (laser diode), an LED (light emitting diode) and the like are preferable, and an LD is particularly preferable. When an LD is used as the excitation means, no resonator is required. The fundamental wave oscillation means may further include an oscillation control means for pulsing the emitted laser light and / or stabilizing the wavelength of the laser light.

Tunable laser device 10 according to the present invention
The wavelength variable means used in the present invention is not particularly limited, but preferably includes a wavelength conversion crystal and a wavelength control means. A resonator may be further provided depending on the wavelength conversion crystal used. As the wavelength conversion crystal, for example, a domain-inverted crystal is used. The domain-inverted crystal is a ferroelectric crystal having both a wavelength conversion function and a phase modulation function, for example, LiNbO ₃ (LN), LiTaO ₃
(LT), KTiOPO ₄ (KTP), KTiOAsO
₄ (KTA), RbTiOAsO ₄ (RTA) and the like.

The above-mentioned domain-inverted crystal may be of a single type, or a multi-inversion type in which one domain-inverted crystal comprises two or more portions having different inversion periods. You may. In addition, the polarization inversion is not limited to the inversion at a fixed cycle, but may be a mode of inversion that is not a fixed cycle. Only one domain-inverted crystal may be used, or two or more domain-inverted crystals may be used in tandem in the optical axis direction.

The wavelength control means is means for changing the wavelength of the laser beam by exerting some action on the wavelength conversion crystal, and includes, for example, a power application means. The power applying means may be, for example, one known or put into practice in the field of a conventional laser including a pair of electrodes. When forming an electrode on the domain-inverted crystal,
In addition to being formed on the entire crystal surface, only the inversion region having the same polarity may be selected and formed so that a voltage is effectively applied only to that portion. Regions may be mixed and selected at a required ratio, and formed so that a voltage is applied to those portions. When a voltage is applied to the domain-inverted crystal, the domain-inverted period and the inversion ratio change due to the electro-optic effect, thereby enabling generation of the second harmonic and wavelength conversion by optical parametric oscillation. Such a domain-inverted crystal is prepared so as to have an inversion period and a crystal length appropriately corresponding to the wavelength of the fundamental wave and the wavelength of the desired wavelength-converted light.

The wavelength control means may change the wavelength of the laser light by controlling the temperature of the crystal, or may change the wavelength of the laser light by applying pressure to the crystal. Is also good.

With such a wavelength tunable laser device 10, it is possible to sequentially switch and emit laser light of at least two or more wavelengths as described above. Laser light of two or more wavelengths emitted from the wavelength tunable laser device 10 passes through the transmission optical system 11 and is sequentially applied to the detection region R as irradiation light 3. The transmission optical system 11 is not particularly limited, and depends on an environmental condition in which the road surface state detection device 1 is installed and an object A to be detected in the detection region R,
It is appropriately selected so as to realize an arbitrary irradiation pattern.

The irradiation pattern of the irradiation light 3 may be realized, for example, in a spot shape, or may be realized so as to uniformly irradiate the detection region R. FIG. 3 shows a simplified example of a preferred example in which the transmission optical system 11 is realized by a spot-shaped irradiation pattern 12 in the case of detecting the freezing of the road surface 2a using the road surface state detection device 1 of the present invention as in FIG. FIG. When the transmission optical system 11 is realized by a spot-shaped irradiation pattern 12 as shown in FIG. 3, for example, a galvano scanner, a polygon mirror, an acousto-optic deflector, etc., capable of continuously scanning a two-dimensional plane are preferable. In particular, a galvano scanner is preferably used. In this manner, by continuously scanning the two-dimensional plane and sequentially receiving the reflected light 4 for each point in the detected area R by the light receiving means 6 described later, the detected area R can be two-dimensionally scanned. It can be detected as image information. With such two-dimensional image information, it is possible to obtain, for example, a state in which ice and water are mixed on the road surface 2a as described later.

When the irradiation pattern of the irradiation light 3 is realized so as to uniformly irradiate the detection region R, for example, a wavelength tunable laser device 10 using a diffusion plate is used.
The laser light emitted from may be diffused uniformly,
Further, the laser light may be expanded using a plurality of lenses. Among them, the above-mentioned diffusion plate is particularly preferably used. Even when the detection area R is uniformly illuminated in this way, the reflected light 4 is received by the light receiving unit 6 so that
The detected region R can be detected as two-dimensional image information.

The light receiving means 6 includes a light receiver 13 and a receiving optical system (not shown). The light receiving means 6 transmits the reflected light 4 obtained by reflecting the irradiation light 3 radiated from the light irradiating means 5 in the detection region R via the receiving optical system.
Are sequentially received in synchronization with the switching of the irradiation light 3 of the
Converts the reflected light 4 received into the electric signal. Each of the electric signals converted from the reflected light 4 is sent to the operation determining means 7 described later. The reflected light 4 includes a reflected light 4a in which the detection light 3a is reflected in the detected area R and a reflected light 4b in which the reference light 3b is reflected in the detected area R.

The light receiver 13 is not particularly limited as long as it has a sensitivity corresponding to the irradiation light 3 by the light irradiation means 5, and various types of conventionally known or practically used photodiodes, for example, InGaAs System, InAs
System, Ge system, HgCdTe system, GaAs system, InP system,
It is realized by a light receiving element such as an InSb-based photodiode or an infrared camera such as an infrared vidicon camera. If necessary, an optical filter such as a wavelength selection filter may be attached to the light receiving portion of the light receiver 13 on the receiving optical system side. The receiving optical system is not particularly limited, and is realized by, for example, a lens, various telescopes, or the like.

The calculation judging means 7 calculates the reflected light 4a of the detection light 3a reflected by the detected area R obtained by the light receiving means 6.
Of the reflected light 4b of the reference light 3b reflected by the detected area R and the electric signal of the reflected light 4b, and a comparison operation of the electric signal of the reflected light 4a and the electric signal of the reflected light 4b. Then, the presence or absence of the detection target A in the detection target region R is determined. Thereby, the road surface condition detecting device 1 of the present invention detects the condition of the detected region R on the road surface 2a of the road 2.

The communication means 8 is a means capable of remotely communicating the determination result obtained by the arithmetic determination means 7 and is not particularly limited, and is realized by a conventionally known communication means. Specifically, optical fiber cable, coaxial cable,
Examples include various communication cables and wireless devices using millimeter waves, and are preferably realized by optical fiber cables. The determination result of the state of the detected region R is transmitted to the monitoring center 16 by such a communication unit 8, for example.

The control means 9 controls the light irradiating means 5, the light receiving means 6, the operation determining means 7 and the communication means 8 described above.

The road condition detecting device 1 has a power source (not shown) for supplying electric power for operating the road condition detecting device 1. The power may be realized so as to be supplied from the outside via a cable or the like, or the road surface state detecting device 1 may be realized to include a battery. Further, a configuration in which electricity is stored in a solar panel may be used. Such a road surface condition detecting device 1 includes a housing 1
In the embodiment shown in FIG. 1, the light irradiating means 5, the light receiving means 6, the arithmetic determination means 7, the communication means 8, and the control means 9 are accommodated in the housing 14. You. Further, the road surface state detecting device 1 of the present invention
Are light irradiating means 5 and light receiving means 6 and arithmetic determining means 7,
The communication means 8 and the control means 9 are housed in separate housings, respectively. In the installation example shown in FIGS. 2 and 3, only the housing housing the light irradiation means 5 and the light receiving means 6 is mounted on the side of the road 2 at a height to be described later. It may be realized to be installed at a position.

The material, shape, volume and the like of the housing 14 are not particularly limited, but the road surface condition detecting device 1 is easily exposed to outside air, for example, beside the road 2 as in the installation example shown in FIGS. When installed in a place, the housing 14 is preferably formed of a weatherproof material having waterproof and dustproof properties. As a result, the light irradiating means 5, the light receiving means 6, the calculation judging means 7, the communication means 8 and the control means 9 accommodated in the housing 14 are not exposed to rainwater and are not affected by direct sunlight, and therefore the road surface condition is not affected. The detection device 1 can detect the detection target region R without being adversely affected by the surrounding environment in which the detection device 1 is installed. Further, the road surface condition detecting device 1 of the present invention may further be provided with a temperature adjusting means such as a heater, so that the temperature of the internal space of the housing 14 can be kept constant.

As shown in the installation example of FIG. 2, such a road surface state detecting device 1 is mounted on a long columnar installation member 15 fixed in advance beside the road 2, for example, at an appropriate height from the road surface 2a. Installed so that The installation member 15
Is fixed such that its longitudinal direction is substantially perpendicular to the road surface 2a. The height position at which the road surface condition detection device 1 is installed is such that the height h from the road surface 2a to the center of gravity G of the road surface condition detection device 1 is preferably 0.1 to 100 m, more preferably 3 to 10 m. Will be installed. If the height h is less than 0.1 m, it is not preferable because there is a problem that the passage of a person or a vehicle hinders the detection, and the snow and the water easily enter. Conversely, if the height h exceeds 100 m, there is a disadvantage that the wind is liable to be adversely affected by wind, such as blurring.

The irradiation light 3 containing the detection light 3a and the reference light 3b irradiated to the detection area R by the light irradiation means 5 of the road surface condition detection device 1 of the present invention is preferably both infrared rays. Since the irradiation light 3 is all infrared rays, the detection by the road surface condition detection device 1 is hardly affected by visible light, and therefore, the detection can be stably performed in the detection region R of the road surface 2a of the road 2 without distinction between day and night. Thing A
Can be detected.

The road 2 on which the road surface condition detecting device 1 of the present invention shown in FIGS. 2 and 3 is installed may be a road provided with a road freezing prevention means (not shown) in advance. Examples of the road freezing prevention unit include a road heating device, a snow melting facility including a water spraying unit and a chemical spraying unit, and a road heating device is particularly preferable. The road freezing prevention means includes at least the road surface 2a transmitted from the communication unit 8 of the road surface state detection device 1.
When the result of the determination that the vehicle is frozen is received, the thawing of the frozen road surface is started. Such a road freezing prevention unit may set a determination result that the road surface 2a is transmitted from the communication unit 8 is frozen as a start signal thereof, or the monitoring center 16 may perform the above-described determination. The monitoring center 16 may be set to be started automatically by the monitor at the monitoring center 16 when the determination result is received or automatically at the monitoring center 16.

FIG. 4 is a graph showing infrared absorption spectra 21 and 22 of ice and water, respectively. In FIG. 4, the vertical axis represents absorbance (%), and the horizontal axis represents wavelength (μ).
m). As shown by the solid line absorption spectrum 21 in FIG. 4, ice has a first peak 23 at 1.50 μm and a second peak 24 at 1.98 μm as absorption wavelengths. Also, as shown by the absorption spectrum 22 indicated by the broken line,
Water irradiated with infrared light has a first peak 25 at 1.45 μm and a second peak 26 at 1.94 μm.
Such peaks indicating the specific absorption wavelengths in the infrared wavelength regions of ice and water are based on the vibration of OH molecules constituting each of ice and water.

In the road surface condition detecting device 1 of the present invention, when the detected object A is, for example, ice, the light having a wavelength of 1.50 μm at which the first peak 23 appears in the absorption spectrum 21 shown in FIG. 27 or the light 28 having a wavelength of 1.98 μm where the second peak 24 appears is detected light 3
Set as a. The light 27 or the light 28 having the above-described wavelength is emitted as the detection light 3a to the detection region R of the road surface 2a of the road 2, and the reflected light 4a is received by the light receiving means 6. When ice exists in the detection area R, the detection light 3a is absorbed by the ice in the detection area R and attenuated. Thereby, it can be determined that ice exists in the detection region R. In principle, it is also possible to determine the presence or absence of ice in the detection region R by comparing the light intensity of the reflected light 4a of the detection light 3a in each case of the presence or absence of ice in the detection region R as described above. However, in order to perform more accurate detection, the road surface condition detection device 1 of the present invention irradiates the reference light 3b in addition to the detection light 3a.

The reference light 3b is light having a wavelength close to the detection light 3a and hardly absorbed by the object A as described above. When the detection target A is ice, when the light 27 having a wavelength of 1.50 μm is selected as the detection light 3a, for example, the light absorption is close to the first peak 23 and the absorbance is about the same as the absorbance at the first peak 23. The wavelength of the portion 29 which is half and substantially parallel to the horizontal axis, preferably 1.0 to 1.4 μm, more preferably 1.3 to 1.4 μm, and particularly preferably 1.4.
The light 30 having a wavelength of 0 μm is set as the reference light 3b. When the light 28 having a wavelength of 1.98 μm is selected as the detection light 3a, for example, the absorbance is close to the second peak 24 and the absorbance is about 1/3 or less of the absorbance at the first peak 23, and the horizontal axis indicates The wavelength of the substantially parallel portion 31, preferably 1.6 to 1.9 µm, more preferably 1.7 to 1.9 µm
The light 32 having a wavelength of m, particularly preferably 1.80 μm, is set as the reference light 3b.

The detection light 3a and the reference light 3b having the above-mentioned wavelengths are sequentially switched by the light irradiating means 5 to irradiate the detection region R, and each of the reflected lights 4a and 4b received by the light receiving means 6 The electrical signal is compared and calculated by the calculation determining means 7 by taking, for example, a difference, so that the electrical signal is not influenced by the difference in the degree of light reflection (reflectance) due to the material of the detection region R, the climate, and other surrounding environments. The presence / absence of ice in the detection region R can be determined with high sensitivity without distinction and without being influenced by extraneous light, and the detection of the freezing of the detection region R can be performed. The order of irradiation of the detection light 3a and the reference light 3b is not particularly limited.

The object to be detected A may be water. In this case, in the absorption spectrum 22 shown in FIG. 4, the light 33 having a wavelength of 1.45 μm where the first peak 25 appears or the second peak 26 appears.
The light 34 having a wavelength of 94 μm is set as the detection light 3a.
When the light 33 is used as the detection light 3a, the light 30 having a wavelength in the vicinity of 1.40 μm may be set as the reference light 3b as in the case of the above ice.
When 4 is used as the detection light 3a, the light 32 having a wavelength near 1.80 μm may be set as the reference light 3b. The detection light 3a and the reference light 3b set in this manner are sequentially switched by the light irradiating means 5 to irradiate the detection area R in the same manner as in the case where the detection object A is ice, and received by the light receiving means 6. The electric signal of each of the reflected lights 4a and 4b is subjected to a comparison operation, for example, by taking a difference by the operation judging means 7 to judge the presence or absence of water in the detection region R with high sensitivity, and to wet the detection region R. And drying can be detected.

The road condition detecting apparatus 1 of the present invention determines whether the detected area R on the road surface 2a of the road 2 is water or ice and freezes, wets and dries the detected area R. May be a detection device for detecting the In other words, the detected area R is detected by the road surface condition detecting device 1 of the present invention.
The detection target A for which the presence or absence is determined may be ice and water. FIG. 5 is a diagram schematically showing irradiation of the detection area R with the detection light 3a and the reference light 3b. It is assumed that ice 36 and water 37 are mixed on the road surface 2a including the detection region R. In this case, the light irradiating means 5 of the road surface condition detecting device 1 irradiates at least three types of light, the first detection light 3a1, the second detection light 3a1, and the reference light 3b.

In such a road surface condition detecting device 1,
The detection light 3a emitted by the light irradiation means 5 includes a first detection light 3a1 having the same wavelength as the absorption wavelength of the ice 36 and a second detection light 3a2 having the same wavelength as the absorption wavelength of the water 37. . As the first detection light 3a1, the above 1.50 is used.
Light 27 having a wavelength of μm or light 28 having a wavelength of 1.98 μm
Set. As the second detection light 3a2, the above-mentioned 1 ..
Light 33 having a wavelength of 45 μm or light 34 having a wavelength of 1.94 μm is set.

The reference light 3b has a first reference light 3b1 and a second reference light 3b2 having the same or different wavelengths.
And The first reference light 3b1 is light having a wavelength close to the first detection light 3a1 and hardly absorbed by the ice 36. The second reference light 3b2 is light having a wavelength close to the second detection light 3a2 and hardly absorbed by the water 37. First and second reference beams 3b1, 3
b2 is set as light having the same wavelength when light having wavelengths close to each other is selected as the first and second detection lights 3a1 and 3a2. More specifically, for example, the first detection light 3a1 is a light 27 having a wavelength of 1.50 μm.
Is set to 1.45 μm as the second detection light 3a2.
Is set as the first and second reference lights 3b1 and 3b2, for example, both are set to 1.4.
The light 30 having a wavelength around 0 μm may be set.

The first and second reference beams 3b1, 3b
When b2 does not select light having wavelengths close to each other as the first and second detection lights 3a1 and 3a2, light having different wavelengths having wavelengths close to the detection lights 3a1 and 3a2 may be selected. More specifically, for example, when the light 27 having a wavelength of 1.50 μm is set as the detection light 3a1 and the light 34 having a wavelength of 1.94 μm is set as the second detection light 3a2, the first reference light 3b1 is set. The light 30 having a wavelength around 1.40 μm may be set, and the light 34 having a wavelength around 1.80 μm may be set as the second reference light 3b2.

The light irradiating means 5 according to the present invention includes the first and second detection lights 3a1 and 3a2 and the first and second detection lights 3a1 and 3a2.
And the second reference light beams 3b1 and 3b2 are sequentially switched to the detected area R of the road surface 2a and irradiated. The order of irradiation of each of these irradiation lights is not particularly limited.

As described above, the first and second detection lights 3a1 and 3a2 and the first and second reference lights 3b1 and 3b2, which are sequentially switched and applied to the detection region R, are reflected by the detection region R, respectively. Reflected light 4 of first detection light 3a1
a1, the reflected light 4a2 of the second detection light 3a2, the reflected light 4b1 of the first reference light 3b1, and the reflected light 4b2 of the second reference light 3b2 are converted by the light receiving means 6 into the light 3 of the irradiation light 3 of the light irradiation means 5. Light is sequentially received in synchronization with the switching, and each is converted into an electric signal. Further, in the operation determining means 7,
The electric signal of the reflected light 4a1 of the first detection light 3a1 is compared with the electric signal of the reflected light 4b1 of the first reference light 3b1, and the electric signal of the reflected light 4a2 of the second detection light 3a2 is compared with the second signal. By comparing and calculating the electric signal of the reflected light 4b2 of the reference light 3b2, the presence or absence of ice and water on the road surface 2a can be determined, and the freezing, wetness, and drying of the road surface can be detected. Further, it is also possible to detect a state in which ice and water are mixed in the detection area R as shown in FIG. This makes it possible to accurately determine whether water or ice exists in the detection region R at a low cost, without the need for providing a large number of fixed point sensors and the like in the detection region R, as compared with the related art. be able to.

FIG. 6 is a simplified diagram showing another preferred installation example of the road surface condition detecting device 1 of the present invention. In the installation example shown in FIG. 6, the road surface state detection device 1 includes an installation member 4 on a roof 42 of a moving vehicle such as an automobile 41.
3 is installed. If installed as described above,
The road surface state detecting device 1 includes an axis L1 imagined as an optical axis of a laser beam emitted from the wavelength tunable laser device 10.
And an angle θ1 on the side of the vehicle 41 between the road surface 2a and the road surface 2a is set to be an acute angle. The angle of the angle θ1 is determined by the vehicle 41
The distance D from the front end 41a on the front side in the traveling direction B to the detected area R on the road surface 2a to the side of the automobile 41 is preferably 5 to 500 m, more preferably 10 to 100 m. In other words, the road surface state detecting device 1
Is preferably 5 to 50 in front of the traveling direction B of the automobile 41.
It is installed so that the state of the road surface 2a of 0 m, more preferably 10 to 100 m can be detected.

By installing the road surface condition detecting device 1 as described above, the road surface 2a in the forward direction B of the vehicle 41 is provided.
The irradiation light 3 is sequentially switched by the light irradiation means 5 to irradiate the vehicle, and based on the reflected light 4, the detection region R is continuously moved in the traveling direction B with the movement of the vehicle 41, It is possible to continuously determine whether or not ice and / or water exists on the road surface 2a in front of 41, and to continuously detect the state of the road surface 2a. Such a determination result is notified to a driver operating in the automobile 41 via, for example, a communication unit 8 (not shown). This makes the car 4
The driver who drives the vehicle 1 moves in the traveling direction B in advance while driving.
It is possible to know the state of the road surface 2a ahead, and it is easier to avoid a traffic accident caused by the freezing of the road surface than in the case where the state of the road surface 2a ahead cannot be known in advance in this way, thereby improving safety. Is done.

FIG. 7 is a view schematically showing still another preferred installation example of the road surface condition detecting device 1 of the present invention. In the installation example illustrated in FIG. 7, the road surface state detection device 1 is installed in a portion 46 of the body of an aircraft such as an airplane 45 on the side closer to the detection region R. The road 2 having the road surface 2a including the detected region R as one region is, for example, a runway on which the airplane 45 in a flying state is about to land as shown in FIG. By installing the road surface condition detecting device 1 on the airplane 45 in this manner,
Irradiates the runway that he is about to land by sequentially switching the irradiation light 3 by the light irradiation means 5 and, based on the reflected light 4, determines whether or not ice and / or water exists on the runway. ,
The state of the road surface 2a is detected. Such a determination result is notified to a pilot who operates the airplane 45 in the airplane 45 via, for example, a communication unit 8 (not shown). As a result, the pilot who operates the airplane 45 can know the condition of the road surface 2a of the runway in advance, and as a result of the road surface freezing as compared with the case where the condition of the road surface 2a cannot be known in advance in this way. It is easier to avoid landing accidents and safety is improved. It is also possible to detect that an aerial image of a highway or the like is taken from the sky in addition to the runway.

The road surface condition detecting device 1 of the present invention is not limited to the detection of freezing and / or wetting and drying of the road surface 2a by the determination of ice and / or water on the road surface 2a as described above, It can also be applied to snowfall detection. It can also be applied to soil moisture detection and marine pollution surveys.

[0052]

As is apparent from the above description, according to the present invention, the presence / absence of an object in the area to be detected is determined stably without distinction between day and night and without being affected by extraneous light. The state of the area can be detected, and when the object to be detected is ice and water, it is easier to determine whether the object on the road surface is ice or water, and the road surface is detected. It is possible to provide a road surface condition detection device that can detect road surface conditions such as freezing, wetness, and dryness.

[Brief description of the drawings]

FIG. 1 is a simplified block diagram showing a preferred example of a road surface condition detecting device 1 of the present invention.

FIG. 2 is a simplified view showing a preferred installation example of the road surface condition detecting device 1 of the present invention.

FIG. 3 shows a transmission optical system 11 of the road surface condition detecting device 1 of the present invention.
FIG. 3 is a simplified diagram showing a preferred example realized by a spot-shaped irradiation pattern 12.

FIG. 4 is a graph showing respective infrared absorption spectra 21 and 22 of ice and water.

FIG. 5 shows a detection light 3a and a reference light 3b to a detection area R;
It is a figure which shows irradiation of a pattern typically.

FIG. 6 is a simplified view showing another preferred installation example of the road surface condition detecting device 1 of the present invention.

FIG. 7 is a diagram schematically illustrating still another preferred installation example of the road surface condition detecting device 1 of the present invention.

FIG. 8 is a simplified view of a conventional road surface state detection device 51.

FIG. 9 is a simplified block diagram of a conventional road surface state detecting device 61.

[Description of Signs] 1 Road surface condition detection device 2 Road 2a Road surface 3 Irradiation light 3a Detection light 3b Reference light 4 Reflection light 4a Reflection light of detection light 4b Reflection light of reference light 5 Light irradiation means 6 Light reception means 7 Calculation judgment means 8 Communication means 9 Control means R Detected area A Detected object

Continued on the front page (72) Inventor Teruhisa Inomata 1-23-9 Imaike-cho, Anjo-shi, Aichi F-term in the Okazaki Development Center, Mitsubishi Cable Industries, Ltd. (Reference) 5H180 CC02 CC03 CC03 CC07 EE13

Claims (4)

[Claims] A detection light having a same wavelength as a predetermined absorption wavelength of an object to be detected and a wavelength close to the detection light and having a transmission optical system and a wavelength-variable laser device. A light irradiating means for sequentially switching irradiation light of two or more wavelengths containing a reference light which is difficult to be absorbed and irradiating a detected area on a road surface of a road, a receiving optical system and a light receiver, the light irradiating means comprising: A light receiving means for sequentially receiving the reflected light reflected from the detection area by the irradiation light irradiated from the detection area in synchronization with the switching of the irradiation light of the light irradiation means and converting the reflected light into an electric signal; Calculating and comparing means for comparing the electric signal of the reflected light with the electric signal of the reflected light of the reference light to determine the presence or absence of an object in the detected area; Communication means capable of communicating, A road surface condition detecting device for detecting a state of a detected area, comprising: a light irradiating unit, a light receiving unit, a calculation determining unit, and a control unit for controlling a communication unit. 2. The road surface condition detecting device according to claim 1, wherein the detection light and the reference light are both infrared rays. 3. The object to be detected is ice and water, wherein the detection light has a first detection light having the same wavelength as the absorption wavelength of ice and a second detection light having the same wavelength as the absorption wavelength of water. A first reference light having a wavelength close to the first detection light and hardly absorbed by ice, and a wavelength close to the second detection light; The second that is hardly absorbed by water
1 having the same or different wavelength from the reference light of
At least one kind of light, wherein the operation determining means performs a comparison operation between an electric signal of the reflected light of the first detection light and an electric signal of the reflected light of the first reference light, and By comparing and calculating the electric signal of the reflected light and the electric signal of the reflected light of the second reference light, the presence or absence of ice and water in the detected area of the road surface of the road is determined,
The road surface condition detecting device according to claim 1, wherein the detection unit detects freezing, wetting, and drying of the detection area. 4. The road according to claim 1, wherein the road is provided with a road surface freezing prevention unit that starts prevention of road surface freezing when receiving a determination result that the road surface is frozen transmitted by the communication unit. The road surface condition detecting device according to claim 3, wherein