JP7440760B2 - laser radar equipment - Google Patents

Description

The present disclosure relates to a laser radar device.

Patent Document 1 discloses a laser radar device that detects the distance to an object that reflects laser light by emitting pulsed laser light and receiving reflected light. A laser radar device is provided with a window for emitting laser light and receiving reflected light. Such a window is formed by closing an opening formed on the front surface of the laser radar device with a light-transmitting plate made of glass, resin, or the like and capable of transmitting radar light.

Japanese Patent Application Publication No. 2020-012759

Incidentally, laser radar devices are often housed in a case with a sealed structure that satisfies dustproof and waterproof properties. The reason for this is that it is intended to be used outdoors. Inside the casing of a laser radar device, there is an electric circuit and a motor that drives a rotating mirror, and the temperature inside the casing tends to be higher than that outside the casing. When the temperature outside the housing suddenly drops due to changes in the weather, the transparent plate is cooled down and condensation forms on the inner surface of the transparent plate. Condensation degrades the measurement performance of laser radar devices. Therefore, it is desirable to detect the occurrence of condensation as early as possible. However, in the past, sufficient consideration has not been given to detecting the occurrence of dew condensation at an early stage. Such a problem is common not only to outdoor laser radar devices but also to indoor laser radar devices.

The present disclosure has been made to solve at least part of the above-mentioned problems, and can be realized as the following forms.

(1) According to one embodiment of the present disclosure, a laser radar device is provided. This laser radar device includes a laser radar optical system having a light emitting part that emits pulsed laser light and a light receiving part that receives reflected light of the laser light, and a laser radar optical system that accommodates the laser radar optical system and has an opening. a light transmitting plate disposed so as to close the opening and allowing the laser light and the reflected light to pass through, the light transmitting plate having a thinner part that is thinner than other parts; A distance measuring unit that measures the distance to the object that reflected the laser beam, and a measurement result of the distance measuring unit on the thin portion of the transparent plate to determine whether or not condensation has occurred on the transparent plate. A dew condensation determination section.
In this laser radar device, the outside temperature is easily transmitted to the thin wall portion of the transparent plate, so the temperature of the thin wall portion becomes lower than that of other portions, and dew condensation occurs on the thin wall portion faster than the other portions. According to this laser radar device, it is determined whether or not dew condensation has occurred on the light-transmitting plate using the measurement results of the distance measuring unit in the thin-walled part, so that it is possible to detect the occurrence of dew condensation on the light-transmitting plate at an early stage. I can do it.
(2) In the laser radar device of the above embodiment, the dew condensation determination unit may notify an external device that dew condensation has occurred on the laser radar device when dew condensation has occurred on the transparent plate. good.
According to this type of laser radar device, occurrence of dew condensation can be notified to an external device at an early stage.
(3) The laser radar device of the above embodiment further includes a heating section that heats the light-transmitting plate, and the dew condensation determining section causes the heating section to heat when dew condensation has occurred on the light-transmitting plate. It is also possible to transmit a heating command to start the heating.
According to this type of laser radar device, when dew condensation occurs, the condensation can be eliminated by heating the transparent plate with the heating section. In particular, by heating the light-transmitting plate in the heating section before dew condensation occurs over the entire area of the light-transmitting plate, it is possible to prevent deterioration in measurement performance over the entire area of the light-transmitting plate. Furthermore, unnecessary power consumption can be reduced by operating the heating section only when dew condensation occurs.
(4) In the laser radar device according to the above aspect, the dew condensation determining section is configured to determine whether the measurement result of the distance measuring section at least in a portion of the thin section is based on an effective distance value indicating that an object exists outside. It may be determined that dew condensation has occurred on the transparent plate when the distance value changes to an invalid distance value indicating that no object exists.
In the configuration of the present disclosure, when dew condensation occurs, the measurement result of the distance determination unit changes from an effective distance value to an invalid distance value. Therefore, the presence or absence of dew condensation can be determined by using the measurement results of the distance measuring unit at a specific position of the thin portion.
(5) In the laser radar device of the above embodiment, the dew condensation determination unit determines that dew condensation has occurred on the transparent plate when the invalid distance value is continuously detected within a predetermined period. It may also be something to do.
According to this type of laser radar device, the possibility of determining dew condensation due to noise or erroneous determination can be reduced.
(6) In the laser radar device of the above embodiment, the thin portion may be provided at a position outside the distance measurement angle range of the laser radar device and within the emission angle range of the laser beam. .
According to this type of laser radar device, occurrence of dew condensation can be detected without affecting the distance measurement of the laser radar device.

FIG. 2 is a side view showing the external shape of the laser radar device. FIG. 2 is a front view showing the external shape of the laser radar device. FIG. 2 is an explanatory diagram of the internal configuration of a laser radar device. FIG. 3 is a cross-sectional view of a transparent plate in the first embodiment. FIG. 2 is a block diagram showing a configuration related to dew condensation determination in the first embodiment. An explanatory diagram showing an example of distance measurement results when there is no dew condensation. An explanatory diagram showing an example of distance measurement results when there is dew condensation. An explanatory diagram showing an example of installation of a laser radar device. FIG. 3 is a cross-sectional view of a light-transmitting plate in a second embodiment. FIG. 3 is a perspective view showing the configuration of a heating section that heats a transparent plate. FIG. 3 is an explanatory diagram showing the configuration of a heating section. FIG. 3 is a plan view showing the detailed configuration of a variable resistor. FIG. 7 is a block diagram showing a configuration related to dew condensation determination in a second embodiment. FIG. 3 is an explanatory diagram schematically showing a current flowing through a conductive film in a state where snow is locally attached to a transparent plate. FIG. 3 is a cross-sectional view of a light-transmitting plate in a third embodiment.

A. First embodiment:
FIG. 1 is a side view of a laser radar device 500 as an embodiment of the present disclosure, and FIG. 2 is a front view thereof. FIG. 1 shows X, Y, and Z axes that are orthogonal to each other. In this embodiment, the XY plane is a plane parallel to the horizontal direction. Further, the +Z direction indicates vertically upward. In this embodiment, the +X direction and the -X direction are collectively referred to as the "X-axis direction." Similarly, the +Y direction and the -Y direction are collectively referred to as the "Y-axis direction," and the +Z direction and the -Z direction are collectively referred to as the "Z-axis direction," respectively. The X, Y, and Z axes shown in the other drawings correspond to the X, Y, and Z axes shown in FIG.

Laser radar device 500 houses sensor section 200. The sensor unit 200 specifies the position and size of an object by emitting pulsed laser light as irradiation light R1 and receiving the reflected light R2. In this embodiment, the laser light is infrared light.

Laser radar device 500 includes an upper case section 510, a lower case section 520, and a transparent plate 100. The upper case part 510 and the lower case part 520 correspond to the "case" in this disclosure. Upper case section 510 is located at the top of laser radar device 500 and covers sensor section 200 from above. The upper case portion 510 has a semi-dome shape in appearance. In this embodiment, the upper case portion 510 is made of resin. As the resin, for example, polyethylene, engineering plastic, acrylic resin, etc. are used. Note that instead of resin, it may be formed of metal such as aluminum or stainless steel.

As shown in FIGS. 1 and 2, the lower case section 520 is located at the center and bottom of the laser radar device 500, and covers the sensor section 200 from the sides and below. The top of the lower case part 520 is connected to the bottom of the upper case part 510. In this embodiment, the lower case part 520 is made of the same material as the upper case part 510. An opening 530 is formed in the upper part of the lower case part 520. The opening 530 emits the irradiated light R1 to the outside through the transparent plate 100, and also transmits the reflected light R2 arriving from the outside to the sensor section 200. The opening 530 is also referred to as a "window 530," and the portion surrounding the opening 530 is referred to as a "window frame portion 532."

The transparent plate 100 closes the opening 530. The transparent plate 100 is transparent to laser light. Therefore, the sensor unit 200 can irradiate the irradiation light R1 to the outside through the light-transmitting plate 100, and can also receive the reflected light R2 arriving from the outside through the light-transmitting plate 100. In this embodiment, the transparent plate 100 is made of glass. Note that instead of glass, it may be formed of resin such as polyethylene, engineering plastic, or acrylic resin. The transparent plate 100 has a substantially fan-shaped developed planar shape. In the assembled state, that is, in the used state, the vertically upper side and the vertically lower side of the transparent plate 100 face each other. In other words, these two sides face each other in the Z-axis direction. The Z-axis direction is also called the opposing direction. The light-transmitting plate 100 curves in a direction that intersects this opposing direction (hereinafter also referred to as a "crossing direction"). Specifically, the light-transmitting plate 100 is curved so as to protrude in a direction (−Y direction) that moves away from the sensor unit 200 toward the center in the X-axis direction. In use, the vertically lower side of the transparent plate 100 is shorter than the vertically upper side. For this reason, snow and water that adhere to the transparent plate 100 and slide down the surface of the transparent plate 100 under its own weight gather and accumulate in a relatively narrow area. Preferably, a thin film for antireflection and water repellency is formed on the outer surface of the transparent plate 100.

FIG. 3 is an explanatory diagram of the internal configuration of the laser radar device 500. Laser radar device 500 includes a laser radar optical system 60 and a control device 70. The laser radar optical system 60 includes a light emitting section 10, a light receiving section 20, a mirror 30, and a rotating deflection device 40. The laser radar optical system 60 is an optical device that performs scanning by emitting laser light to the outside and receiving reflected light of the laser light reflected by an external object.

The light emitting unit 10 includes a laser diode 11 that generates laser light and a collimating lens 12. The laser diode 11 is supplied with a pulse current from a drive circuit (not shown) under the control of the control device 70, and emits pulsed laser light (irradiation light R1). The collimating lens 12 is installed on the optical axis of the laser beam R1 emitted from the laser diode 11, and converts the laser beam R1 into parallel light.

The mirror 30 is installed on the optical axis of the laser beam R1 emitted from the light emitting section 10, and reflects the laser beam R1 to the rotating deflection device 40 by the reflecting surface 30a. The rotational deflection device 40 includes a mirror 41 having a flat reflective surface 41a, a support base 43 that supports the mirror 41, a rotation shaft 42 connected to the support base 43, and a drive that rotates the rotation shaft 42. It has a device 44. The rotation shaft 42 is rotatable about a central axis 42a. After the laser beam R1 reflected by the reflective surface 30a of the mirror 30 is incident on the reflective surface 41a of the mirror 41, the mirror 41 reflects the laser beam R1 again and emits it to the outside via the transparent plate 100. Moreover, the mirror 41 scans the laser beam R1 emitted to the outside by rotating together with the rotation shaft 42 about the central axis 42a. Note that the scan angle range of the laser beam R1 centered on the central axis 42a, that is, the angle range in which distance measurement is performed by the laser radar device 500, is preferably set to 180° to 200°.

The light receiving section 20 includes a photodiode 21, a condensing lens 22, and an optical filter 23. The photodiode 21 receives reflected light R2, which is the laser light R1 reflected by an external object. The condensing lens 22 is installed below the photodiode 21 and condenses the reflected light R2 and guides it to the photodiode 21. The optical filter 23 is installed between the photodiode 21 and the condensing lens 22, and transmits the reflected light R2 and removes light of wavelengths other than the reflected light R2. Note that, after receiving the reflected light R2, the photodiode 21 converts the reflected light R2 into an electrical signal and supplies it to the control device 70. Using this electrical signal, the control device 70 can determine, for example, the distance to an external object, the size, position, speed, etc. of the object. Note that the configuration of the laser radar optical system 60 described above is an example, and various configurations other than this can be adopted.

FIG. 4 is a cross-sectional view of the light-transmitting plate 100 in the first embodiment. A part of the light-transmitting plate 100 is provided with a thin portion 110 that is thinner than other parts of the light-transmitting plate 100. Since the outside temperature is easily transmitted to the thin wall portion 110, the temperature of the thin wall portion 110 becomes lower than other portions, and dew condensation occurs on the inner surface of the thin wall portion 110 earlier than other portions. Therefore, by determining the presence or absence of dew condensation using the distance measurement results in the thin wall portion 110, the occurrence of dew condensation can be detected early, before the condensation occurs on the entire transparent plate 100. . A specific method for determining dew condensation will be described later.

FIG. 4 shows the distance measurement angle range Rg of the laser radar device 500 and the emission angle range Rr of the laser beam R1. The distance measurement angle range Rg corresponds to a range defined as an angle range in which distance can be measured in the specifications of the laser radar device 500. The emission angle range Rr is an angle range in which the laser radar optical system 60 scans the laser beam R1. In the first embodiment, the distance measurement angle range Rg and the emission angle range Rr match. However, the emission angle range Rr may be set to a wider range than the distance measurement angle range Rg. In the first embodiment, the thin portion 110 is provided within the distance measurement angle range Rg.

The size of the thin portion 110 is preferably larger than the size of the laser beam R1 emitted from the laser radar optical system 60 when the laser beam R1 passes through the transparent plate 100. The diameter of the laser beam R1 when passing through the transparent plate 100 is typically in the range of 0.5 cm to 1.5 cm. For example, when the diameter of the laser beam R1 is 1 cm, it is preferable that the thin portion 110 has an area that includes a circle with a diameter of 1 cm. Note that the "diameter of the laser beam R1" means twice the Gaussian beam radius (the radius at which the intensity decreases to 13.5% of the peak value).

FIG. 5 is a block diagram showing a configuration related to dew condensation determination in the first embodiment. Here, a control device 70 and a laser radar optical system 60 of a laser radar device 500, and a management device 300 are shown. The management device 300 is an external device that receives measurement results from the laser radar device 500, and uses the measurement results from the laser radar device 500 to manage other devices. The management device 300 includes a display section 310.

The control device 70 of the laser radar device 500 includes a distance measuring section 72 and a dew condensation determining section 74. The distance measurement unit 72 measures the distance to the object that reflected the laser beam R1 from the flight time of the reflected light R2. The dew condensation determination section 74 determines whether or not dew condensation has occurred on the thin section 110 of the transparent plate 100 using the measurement result of the distance measuring section 72 on the thin section 110 of the light transmitting plate 100 . Here, "the measurement result of the distance measuring unit 72 in the thin part 110" means the measurement result in the visual field range corresponding to the thin part 110. Furthermore, when dew condensation occurs on the thin wall portion 110, the dew condensation determination unit 74 notifies the management device 300, which is an external device, of the presence of dew condensation. A notification indicating that dew condensation has occurred in the laser radar device 500 is displayed on the display unit 310 of the management device 300. The administrator who sees this display can know that condensation has occurred in the laser radar device 500, and can therefore take appropriate measures accordingly.

FIG. 6 is an explanatory diagram showing an example of a distance measurement result when there is no condensation, and FIG. 7 is an explanatory diagram showing an example of a distance measurement result when there is dew condensation. These figures show an example of a general case where the light-transmitting plate 100 is not provided with the thin portion 110. In FIGS. 6 and 7, a line that extends outward from the central injection center and then bends in the middle and returns to the injection center indicates that an object exists outside. At this time, the distance measuring section 72 of the laser radar device 500 outputs an effective distance value indicating that an object exists outside as a measurement result. This effective distance value is smaller than the maximum measurable distance of the laser radar device 500. On the other hand, in FIGS. 6 and 7, straight lines extending radially outward in the drawings indicate that no object exists outside the measurement location. At this time, the distance measuring section 72 of the laser radar device 500 outputs an invalid distance value indicating that no object exists outside as a measurement result. This invalid distance value is set, for example, to the maximum measurable distance of the laser radar device 500. Note that the maximum value of the measurable distance of the laser radar device 500 is, for example, in the range of 100 m to 200 m. When the distance measurement unit 72 outputs an invalid distance value, other devices receiving the output can determine that no object exists outside. Further, in the configuration of the present embodiment, the distance measuring section 72 is configured to output an invalid distance value even when dew condensation occurs on the transparent plate 100.

As in the example of FIG. 6, when there is no condensation, the distance measurement result of the laser radar device 500 shows that effective distance values indicating that an object exists outside the laser radar device 500 occur at multiple measurement points. become what you are. On the other hand, as in the example of FIG. 7, when dew condensation occurs, the distance measurement result of the laser radar device 500 changes to an invalid distance value indicating that there is no object outside the laser radar device 500.

The dew condensation determining unit 74 determines whether or not the light transmits through when the distance measurement result at the thin wall portion 110 changes from an effective distance value indicating that an object exists outside to an invalid distance value indicating that no object exists outside. It is determined that dew condensation has occurred on the board 100. In order to perform this dew condensation determination, the laser radar device 500 is installed or installed so that when there is no condensation, the distance measurement result at the thin wall portion 110 indicates an effective distance value indicating that an object exists outside. It is preferable that it be configured.

FIG. 8 is an explanatory diagram showing an example of installation of the laser radar device 500. In this example, the monitoring range R0 in which the laser radar device 500 monitors the presence or absence of an object is narrower than the distance measurement angle range Rg. The monitoring range R0 is set, for example, as a range for monitoring whether or not an object such as a car or a person is present at a railroad crossing. In this case, the reference object 550 is installed outside the monitoring range R0 and inside the distance measurement angle range Rg at a position where the laser beam emitted from the thin section 110 of the transparent plate 100 reaches. Ru. This reference object 550 is used so that when there is no condensation on the thin wall portion 110, the distance measurement result at a specific position on the thin wall portion 110 indicates an effective distance value indicating that an object exists outside. It is an object of. By installing such a reference object 550, it becomes possible for the dew condensation determining section 74 to determine the presence or absence of dew condensation. Note that the reference object 550 does not need to be installed at a location away from the laser radar device 500, and may be installed at a location away from the light-transmitting plate 100 in the case of the laser radar device 500.

The dew condensation determination unit 74 may determine the presence or absence of dew condensation using a method different from the method described above. For example, the following method can be adopted.
<Other condensation determination method 1>
・“If an invalid distance value is continuously detected within a predetermined period, it is determined that condensation has occurred.”
This method is a method in which dew condensation is determined when invalid distance values are continuously detected during a continuous period in order to avoid dew condensation determination due to noise or erroneous determination.
<Other condensation determination method 2>
・“If an invalid distance value is detected a predetermined number of times or more within a predetermined period, it is determined that condensation has occurred.”
This method has the advantage that dew condensation can be determined even in ambiguous situations where condensation does not appear continuously, such as when condensation appears and disappears at delicate temperatures. In this case, unlike the dew condensation determination, it may be configured to determine that a dew condensation preparation period has existed.
<Other condensation determination method 3>
・“If it is detected that the number of positions where the measurement result of the distance measuring unit 72 changes from an effective distance value to an invalid distance value increases gradually or at a constant speed within the range of the thin part 110, it is determined that there is condensation. do."
This determination method focuses on the fact that the area gradually increases due to the natural phenomenon of dew condensation.
<Other condensation determination method 4>
- "Determine the presence or absence of dew condensation using a trained neural network whose input is the measurement result of the distance in the thin section 110 and whose output is the presence or absence of dew condensation.
This method can correctly determine dew condensation through learning of a neural network. In this case, the reference object 550 described above may be omitted.

As described above, in the first embodiment, the thin wall portion 110 is provided in the transparent plate 100, and the measurement result of the distance measuring unit 72 on the thin wall portion 110 is used to determine whether or not dew condensation has occurred on the thin wall portion 110. , it is possible to early detect the occurrence of dew condensation on the transparent plate 100 before the condensation occurs on the entire transparent plate 100 .

B. Second embodiment:
FIG. 9 is a cross-sectional view of the light-transmitting plate 100 in the second embodiment. As can be understood by comparing with FIG. 4, in the second embodiment, a conductive film 410 functioning as a heater is provided on the inner surface of the light-transmitting plate 100.

FIG. 10 is a perspective view showing the configuration of a heating section 400 that heats the transparent plate 100. The heating unit 400 includes a conductive film 410 formed on the inner surface S2 of the transparent plate 100, a pair of electrodes 421 and 422, and three variable resistors 431, 432, and 433. Note that the three variable resistors 431, 432, and 433 are collectively referred to as "variable resistor 430." Variable resistor 430 is optional.

In the present embodiment, the conductive film 410 has a vertically upper side parallel to the vertically upper side of the transparent plate 100 and a vertically lower side of the conductive film 410 that is parallel to the vertically upper side of the transparent plate 100. It is formed so that it is parallel to the vertically lower side of. A conductive film 410 that functions as a heater is formed on the inner surface S2 of the transparent plate 100. This conductive film 410 generates heat when energized and is used to eliminate dew condensation and snow accumulation. The conductive film 410 has a similar shape to the light-transmitting plate 100 and a smaller size than the light-transmitting plate 100. The conductive film 410 is arranged in a planar manner along the inner surface S2 of the transparent plate 100. The conductive film 410 has conductivity and laser light transmittance. In this embodiment, the conductive film 410 is an ITO film (a film of a mixture of indium oxide and tin oxide). Note that not only the ITO film but also any conductive film having laser light transparency such as a silver nanowire film or a conductive polymer film may be used. The conductive film 410 can be formed on the inner surface S2 of the transparent plate 100 by, for example, sputtering, film deposition, CVD (chemical vapor deposition), or the like. Alternatively, the conductive film 410 may be attached to the inner surface S2 of the transparent plate 100.

FIG. 11 is an explanatory diagram schematically showing electrical connections between the conductive film 410, the pair of electrodes 421 and 422, and the variable resistor 430. A pair of electrodes 421 and 422 are used to apply voltage to the conductive film 410. As shown in FIGS. 10 and 11, the upper electrode 421 is disposed above the conductive film 410 on the inner surface S2 of the transparent plate 100, and is electrically connected to the entire vertically upper side of the conductive film 410. It is connected. The lower electrode 422 is disposed on the inner surface S2 of the transparent plate 100 below the conductive film 410 and away from the conductive film 410. The lower electrode 422 has a linear appearance and is arranged parallel to the vertically lower side of the conductive film 410. A pair of electrodes 421 and 422 are connected to a power source 440 and a switch 450.

As shown in FIGS. 10 and 11, the variable resistor 430 is disposed between the vertically lower side of the conductive film 410 and the lower electrode 422, and is electrically connected to the conductive film 410 and the lower electrode 422, respectively. ing. The three variable resistors 431, 432, and 433 are arranged apart from each other in a direction D parallel to the vertically lower side of the conductive film 410. The variable resistor 431 is arranged at a position corresponding to the center of the conductive film 410 along the direction D. The other two variable resistors 432 and 433 are arranged near both ends of the conductive film 410 along the direction D.

FIG. 12 is a plan view showing the detailed configuration of variable resistor 430. All variable resistors 430 have the same configuration. Variable resistor 430 includes a film substrate 435 and an electrical resistance section 436.

The film substrate 435 is formed of a resin film member. As such resin, for example, polyimide, PET, PEN, etc. are used. Note that the film substrate 435 may be formed of glass or Si (silicon) substrate instead of resin.

The electrical resistance section 436 has a line-shaped wiring pattern that is folded back in the direction D and extends in the Z-axis direction. The electrical resistance section 436 is formed of a conductive member. In this embodiment, the electrical resistance section 436 is made of copper. Specifically, the electrical resistance section 436 is formed by depositing a copper film on the surface of the film substrate 435 so as to form the above wiring pattern. Note that instead of copper, any type of conductive material such as silver or iron, which has a lower electrical resistance when the temperature is low than when the temperature is high, may be used. The electrical resistance of variable resistor 430 having such a configuration has temperature characteristics. Specifically, the variable resistor 430 has a characteristic that the electrical resistance value of the variable resistor 430 is smaller when the temperature is low than when the temperature is high. Since the electrical resistance of the variable resistor 430 has the above-described temperature characteristics, the electrical resistance of the variable resistor 430 decreases and the current flowing through the conductive film 410 increases in a low-temperature environment. Therefore, the amount of Joule heat generated in the conductive film 410 increases, and the transparent plate 100 can be further heated. Therefore, dew condensation on the transparent plate 100 can be eliminated, and snow adhering to the transparent plate 100 can be melted.

FIG. 13 is a block diagram showing a configuration related to dew condensation determination in the second embodiment. FIG. 13 shows a heating section 400 added to FIG. 5 described in the first embodiment, and the other configurations are the same as the first embodiment. However, in the second embodiment, the management device 300 can be omitted.

The dew condensation determination section 74 transmits a heating command to the heating section 400 when dew condensation has occurred on the thin section 110 . The switch 450 of the heating unit 400 is switched from off to on in response to a heating command given from the dew condensation determining unit 74, and starts supplying current to the conductive film 410. When the conductive film 410 is energized, dew condensation on the transparent plate 100 is eliminated. When the condensation on the transparent plate 100 is eliminated, it is preferable to terminate the heating by the heating unit 400 in response to a command from the dew condensation determination unit 74.

As described above, in the second embodiment, the heating unit 400 that heats the transparent plate 100 is provided, and the dew condensation determining unit 74 determines whether the heating unit 400 Sends a heating command to start heating. As a result, when there is dew condensation on the transparent plate 100, it is possible to eliminate the condensation by heating the transparent plate 100 with the heating unit 400. In particular, since the heating section 400 can heat the transparent plate 100 before dew condensation occurs over the entire area of the transparent plate 100, deterioration in measurement performance over the entire area of the transparent plate 100 can be prevented. Furthermore, by operating the heating unit 400 only when dew condensation occurs, unnecessary power consumption can be reduced.

Note that the heating unit 400 can also melt snow attached to the transparent plate 100. As will be described in detail below, the variable resistor 430 of the heating unit 400 has a function of melting snow by preferentially heating a portion of the transparent plate 100 on which snow has adhered.

As shown in FIG. 11 described above, when no snow is attached to the transparent plate 100 or when snow is uniformly adhered to the entire area of the transparent plate 100, the current flowing from the upper electrode 421 to the lower electrode 422 is , as shown by the dashed arrows, flows through the conductive film 410 in a distributed manner in the direction D, passes through the three variable resistors 430, and heads toward the lower electrode 422. On the other hand, when snow is locally attached to the transparent plate 100, the current flows differently.

FIG. 14 is an explanatory diagram schematically showing the current flowing through the conductive film 410 in a state where snow is locally attached to the transparent plate 100. In FIG. 14, snow Sn attached to the transparent plate 100 is represented by a two-dot chain line. As explained in FIGS. 1 and 2, the light-transmitting plate 100 is curved so as to protrude in a direction (-Y direction) that moves away from the sensor unit 200 toward the center in the X-axis direction. When snow adheres to the transparent plate 100 due to the wind, more snow adheres vertically below the central portion in direction D in FIG. 14 . In such a situation, the temperature near the variable resistor 431 located in the center will be lower than the temperature near the other two variable resistors 432 and 433. Therefore, the electrical resistance value of the variable resistor 431 is smaller than the electrical resistance values of the other two variable resistors 432 and 433. As a result, the current flowing from the upper electrode 421 to the variable resistor 431 increases, as shown by the broken line arrow in FIG. Therefore, it is possible to locally and preferentially heat the vertically downward central portion of the transparent plate 100 in the direction D, and the snow Sn can be melted. Further, at this time, since a current large enough to flow through the variable resistor 431 does not flow through the variable resistors 432 and 433, the transparent plate 100 is heated excessively at both ends in the direction D, and the transparent plate 100 is deformed. can be restrained from doing so.

As described above, the resistance value of the variable resistor 430 has a characteristic that when the temperature is low compared to when the temperature is high, the current flowing through the variable resistor 430 can be increased at low temperatures, and the conductive film At 410, the temperature of the portion to which the variable resistor 430 is connected can be raised preferentially compared to other portions. Furthermore, since the variable resistor 430 is disposed between the lower electrode 422 and the conductive film 410, it is possible to suppress a narrowing of the laser beam transmission area in the conductive film 410. As a result, the areas that require heating can be heated preferentially while suppressing the narrowing of the area of the transparent plate 100 through which laser light can pass.

Moreover, since the three variable resistors 431 to 433 are arranged apart from each other in the direction parallel to the two sides between the lower electrode 422 and the conductive film 410, the plurality of variable resistors 431 to 433 connected to the variable resistor 430 Even if the temperature of a part is different from each other, a current according to each temperature can flow, specifically, the lower the temperature, the more current can flow, and if the part is partially covered with snow and the temperature is low locally. When such a temperature distribution exists in the transparent plate 100, each part can be appropriately heated.

Further, since the variable resistor 430 is constituted by a film substrate 435 that is transparent to electromagnetic waves and a wiring pattern formed on the film substrate 435 using a conductive material, the variable resistor 430 allows the light-transmitting plate 100 to It is possible to suppress the transmission area of electromagnetic waves from becoming narrower.

Furthermore, since the transparent plate 100 is curved in the cross direction, for example, when the laser radar device 500 is used outdoors, snow, frost, etc. may be locally applied to the transparent plate 100 depending on environmental conditions such as wind direction. Easy to adhere to. However, even in such a situation, since the variable resistor 430 is disposed in a region where snow locally adheres, it is possible to locally heat the region and melt the snow.

Further, in the laser radar device 500, snow adhering to the upper side of the transparent plate 100 tends to slide down and collect due to its own weight near the vertically lower side of the transparent plate 100, and the temperature tends to partially become low. However, even in such a situation, since the variable resistor 430 is disposed in a region that is likely to become low temperature, snow can be removed by locally heating such a region.

In addition, since the variable resistor 430 is disposed between the lower electrode 422 and the conductive film 410, the temperature of the vertically lower portion where snow adhering to the upper part of the transparent plate 100 tends to slide and collect due to its own weight becomes low temperature. The current flowing through the conductive film 410 can be controlled according to the current, and snow can be removed more reliably.

Note that the control device 70 can determine whether or not there is snow on the transparent plate 100 based on the distance measurement result by the distance measurement section 72. For example, if the distance measurement result at at least one point within the distance measurement angle range is a value corresponding to the length of the optical path of the laser beam from the light emitting unit 10 to the surface of the transparent plate 100, snow has accumulated. It is possible to determine that. Alternatively, it is also possible to determine the presence or absence of snow accumulation using a trained neural network that inputs the distance measurement results and outputs the presence or absence of snow accumulation. Note that when determining snow accretion, if only the distance measurement results in the thin wall portion 110 are used, the snow accretion determination can be made more easily than in the case where the distance measurement results over the entire area of the transparent plate 100 are used. It is possible to do so. As a criterion for snow accumulation determination, it may be added that the outside temperature measured by an outside temperature sensor (not shown) is lower than a predetermined snowfall reference temperature. As the snowfall reference temperature, for example, a value in the range of 0°C to 2°C is used. The control device 70 may include a snow accretion determining section that performs any of the snow accretion determinations described above.

C. Third embodiment:
FIG. 15 is a cross-sectional view of a transparent plate 100a in the third embodiment. This transparent plate 100a differs from the second embodiment shown in FIG. 9 in the position of the thin portion 110. Specifically, the thin portion 110 is provided at a position outside the distance measurement angle range Rg of the laser radar device 500 and within the laser beam emission angle range Rr. The emission angle range Rr of the laser beam is larger than the distance measurement angle range Rg of the laser radar device 500. The operations of each device in the second embodiment described with reference to FIG. 13 are the same in the third embodiment.

As described above, in the third embodiment, since the thin portion 110 is provided at a position outside the distance measurement angle range Rg of the laser radar device 500 and within the laser beam emission angle range Rr, the laser radar device 500 The occurrence of condensation can be detected without affecting the distance measurement of the device 500.

D. Other embodiments:
(1) In each embodiment, the thin wall portion 110 is provided on the outer surface of the light transmitting plate 100, but the thin wall portion 110 may be provided on the inner surface of the light transmitting plate 100. However, if the thin portion 110 is provided on the outer surface of the light-transmitting plate 100, there is an advantage that the conductive film 410 as a heater can be easily formed on the inner surface of the light-transmitting plate 100. Further, when the thin wall portion 110 is provided on the outer surface of the light transmitting plate 100, snow tends to adhere to the thin wall portion 110 more easily than other parts of the light transmitting plate 100. This has the advantage of making it easier to detect adhesion at an early stage. On the other hand, if the thin portion 110 is provided on the outer surface of the light-transmitting plate 100, there is an advantage that the conductive film 410 can be easily formed on the inner surface of the light-transmitting plate 100.

(2) In each embodiment, the thin wall portion 110 is provided only at one location on the light transmitting plate 100, but a plurality of thin wall portions 110 may be provided on the light transmitting plate 100.

(3) In the second embodiment, the number of variable resistors 430 is three, but any number may be used. Specifically, it may be one or any plurality of two or more. Further, although the plurality of variable resistors 430 are arranged apart from each other in the direction D, they may be arranged in contact with each other instead.

(4) As the configuration of the variable resistor 430, a PTC (Positive Temperature Coefficient) thermistor may be used instead of the configuration shown in FIG. That is, in general, any type of variable resistor that has a characteristic that the electrical resistance value is smaller when the temperature is low than when the temperature is high can be used in the laser radar device of the present disclosure.

(5) In the second embodiment, the variable resistor 430 is arranged between the conductive film 410 and the lower electrode 422, but instead of or in addition to this, the variable resistor 430 is arranged between the conductive film 410 and the lower electrode 422. It may be arranged between the electrode 421 and the electrode 421.

(6) In each embodiment, the light-transmitting plate 100 is curved in the cross direction, but instead of being curved, it may be bent. Alternatively, it may be flat. Further, in each embodiment, the vertically lower side of the light-transmitting plate 100 is shorter than the vertically upper side, but the present disclosure is not limited thereto. The vertically lower side of the transparent plate 100 may be longer than the vertically upper side, or the lengths of these two sides may be equal to each other.

The present disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from the spirit thereof. For example, the technical features in each embodiment that correspond to the technical features in each form described in the column of the summary of the invention may be used to solve some or all of the above-mentioned problems, or to achieve the above-mentioned effects. In order to achieve some or all of the above, it is possible to perform appropriate replacements or combinations. Further, unless the technical feature is described as essential in this specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10... Light emitting part, 11... Laser diode, 12... Collimating lens, 20... Light receiving part, 21... Photo diode, 22... Condensing lens, 23... Optical filter, 30... Mirror, 30a... Reflective surface, 40... Rotating deflection Device, 41...Mirror, 41a...Reflection surface, 42...Rotation axis, 42a...Center axis, 43...Support stand, 44...Drive device, 60...Laser radar optical system, 70...Control device, 72...Distance measurement section, 74... Dew condensation determination section, 100... Transparent plate, 100a... Transparent plate, 110... Thin wall section, 200... Sensor section, 210... Drive section, 300... Management device, 310... Display section, 400... Heating section, 410... Conductive film, 421... Upper electrode, 422... Lower electrode, 430... Variable resistor, 431... Variable resistor, 432... Variable resistor, 433... Variable resistor, 435... Film substrate, 436... Electric resistance section, 440... Power supply, 450... Switch, 500... Laser radar device, 510... Upper case part, 520... Lower case part, 530... Opening part, 532... Window frame part, 550... Reference object

Claims (6)

A laser radar device,
a laser radar optical system having a light emitting part that emits pulsed laser light and a light receiving part that receives reflected light of the laser light;
a case that houses the laser radar optical system and has an opening;
a light-transmitting plate disposed so as to close the opening and allowing the laser light and the reflected light to pass through, the light-transmitting plate having a thin part that is thinner than other parts;
a distance measuring unit that measures the distance to the object that reflected the laser beam;
a dew condensation determining unit that determines whether or not condensation has occurred on the transparent plate using the measurement result of the distance measuring unit in the thin portion of the transparent plate;
A laser radar device comprising: The laser radar device according to claim 1,
In the laser radar device, the dew condensation determination unit notifies an external device that dew condensation has occurred in the laser radar device when dew condensation has occurred on the transparent plate. The laser radar device according to claim 1 or 2, further comprising:
comprising a heating section that heats the transparent plate,
In the laser radar device, the dew condensation determination unit transmits a heating command to start heating to the heating unit when dew condensation occurs on the transparent plate. The laser radar device according to any one of claims 1 to 3,
The dew condensation determining unit is configured to change the measurement result of the distance measuring unit on at least a portion of the thin portion from an effective distance value indicating that an object exists outside to an invalid distance value indicating that no object exists outside. A laser radar device that determines that dew condensation has occurred on the transparent plate when the temperature changes to . The laser radar device according to claim 4,
The dew condensation determination unit determines that dew condensation has occurred on the transparent plate when the invalid distance value is continuously detected within a predetermined period. The laser radar device according to any one of claims 1 to 5,
A laser radar device, wherein the thin portion is provided at a position outside a distance measurement angle range of the laser radar device and within an emission angle range of the laser beam.

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