Optical window inspection device and lidar device

Abstract

This optical window inspection device comprises: a first projector emitting first detection light that passes through an optical window that allows incident light to pass through; a second projector emitting second detection light that does not pass through the optical window; a light receiver that receives the first detection light and the second detection light and that generates a first voltage corresponding to the intensity of the first detection light received and a second voltage corresponding to the intensity of the second detection light received; and a control unit that corrects the value of the first voltage based on the value of the second voltage and a predetermined reference value, and performs a process that detects contamination on the optical window on the basis of the corrected value of the first voltage.

Description

Technical Field

[0001] The present disclosure relates to an optical window inspection device and a lidar device.

Background Art

[0002] Patent Document 1 discloses a detection device for detecting dirt on an optical window in a scanning distance measuring device that irradiates a measurement object with measurement light through the optical window and measures the distance to the object based on information of the measurement light and the reflected light from the object. The detection device is disposed in the casing of the scanning distance measuring device. The detection device is disposed outside the scanning distance measuring device rather than the optical window provided in the casing. The retroreflective material is disposed in the casing and reflects light. Detection light is irradiated from the light emitting element of the detection device toward the optical window. The irradiated detection light passes through the optical window and enters the retroreflective material. The reflected light from the retroreflective material passes through the optical window. Then, the reflected light is received by the light receiving element of the detection device. The detection device detects dirt attached to the optical window based on the amount of the reflected light (i.e., the reflected detection light) received by the light receiving element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] However, in the prior art, failure in detecting contamination of the optical window can occur. For example, the detection device may fail to detect due to a temperature change in the detection device. It is known that the emission intensity of a light-emitting diode used as a light-emitting element and the output voltage of a photodiode used as a light-receiving element depend on temperature. In the technology of Patent Document 1, when the temperature of the environment where the scanning distance measuring device is arranged changes, the emission intensity of the light-emitting diode and the output voltage of the photodiode change, and the output voltage may deviate from the assumed voltage. When the output voltage is lower than the assumed voltage, even though there is no contamination on the optical window, the detection device may detect contamination on the optical window. That is, false detection may occur. Conversely, when the output voltage is higher than the assumed voltage, even though there is contamination on the optical window, the detection device may not detect the contamination of the optical window. That is, non-detection may occur. Therefore, there is a need for a detection device capable of reducing the failure in detecting contamination of the optical window (that is, the occurrence of false detection and non-detection).

[0005] According to an embodiment of the present disclosure, an optical window inspection device is provided. The optical window inspection device includes a first light projector that emits first detection light that passes through an optical window that transmits incident light, a second light projector that emits second detection light that does not pass through the optical window, and a light receiver that receives the first detection light and the second detection light, wherein a first voltage corresponding to the intensity of the received first detection light and a second voltage corresponding to the intensity of the second detection light are generated, and a control unit that corrects the value of the first voltage based on the value of the second voltage and a predetermined reference value, and performs a process of detecting contamination of the optical window based on the corrected value of the first voltage.

[0006] According to the optical window inspection device of this embodiment, the second detection light does not pass through the optical window and is received by the light receiver. Therefore, the value of the second voltage is not affected by the contamination of the optical window. That is, based on the value of the second voltage and the reference value, it is possible to detect the influences other than the contamination of the optical window. Thereby, by performing the process of detecting the contamination of the optical window based on the value of the first voltage corrected based on the value of the second voltage and the reference value, even if influences other than the contamination of the optical window occur in the optical window inspection device, it is possible to reduce the failure of detecting the contamination of the optical window. For example, even when the temperature of the environment where the optical window inspection device is arranged changes, it is possible to reduce the occurrence of false detection and non-detection of the contamination of the optical window in the optical window inspection device.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0008] A. First Embodiment A1. Configuration of the First Embodiment FIG. 1 is a schematic diagram for explaining a part of the lidar device 1 according to the first embodiment. Although FIG. 1 shows a cross-section of the lidar device 1, the hatching that should be attached to the cut surface is omitted. The lidar device 1 irradiates measurement light, receives reflected light from an object irradiated with the measurement light, and measures the distance between the lidar device 1 and the object based on the reflected light. The lidar device 1 includes a case 10, a distance measurement unit 20, and a detection unit 30 (i.e., an optical window inspection device). In FIG. 1, dirt 40 is attached to the case 10. The distance measurement unit 20 and the detection unit 30 are supplied with power from a power source (not shown).

[0009] The case 10 houses each component of the lidar device 1. The case 10 houses the distance measurement unit 20 and the detection unit 30. The case 10 includes a first case body 110 and a second case body 120.

[0010] The first case body 110 houses the components of the detection unit 30 other than the reflector 340. Specifically, the first case body 110 houses the first light emitter 310, the first light receiver 331, the second light emitter 320, the second light receiver 332, and the control unit 350. The shape of the first case body 110 is a substantially rectangular parallelepiped with one side open. Further, the first case body 110 has a monitor 111 on the outside.

[0011] The monitor 111 displays various screens such as a setting screen and an operation screen based on a display signal input from the control unit 350. In the present embodiment, the monitor 111 is controlled by the control unit 350 to display that the optical window 125 is dirty. The monitor 111 may be, for example, an LCD (Liquid Crystal Display) or an ELD (Electroluminescence display).

[0012] The second case body 120 houses the distance measuring unit 20 and the reflector 340 of the detection unit 30. The second case body 120 is connected to the first case body 110. The second case body 120 includes a side surface 121, an upper surface 122, and a flange 123. The second case body 120 has a shape in which the upper base of a substantially frustum of a cone that is inverted up and down is open, and a flange is provided on the upper base.

[0013] The side surface 121 is formed by an optical window 125 that transmits light. For example, the side surface 121 transmits the measurement light L21 of the distance measuring unit 20, the reflected light L22, and the first detection light L31 of the detection unit 30. The side surface 121 corresponds to the side surface of a substantially frustum of a cone. The upper surface 122 corresponds to the lower base of the substantially frustum of a cone. The upper surface 122 is connected to the side surface 121. The reflector 340 is disposed on the upper surface 122.

[0014] The flange 123 is formed by an optical window 125 that transmits light. For example, the flange 123 transmits the first detection light L31 of the detection unit 30. The flange 123 is joined to the first case body 110. Thereby, the side surface 121, the upper surface 122, and the flange 123 (i.e., the second case body 120) seal the opening of the first case body 110. That is, the inside of the first case body 110 communicates with the inside of the second case body 120. The flange 123 extends outward from the edge 124 of the opening surface corresponding to the upper base of the substantially frustum of a cone of the second case body 120. The flange 123 is a plate-shaped part. It can also be said that the flange 123 and the side surface 121 are constituted by the optical window 125.

[0015] The optical window 125 transmits the incident light. For example, the optical window 125 transmits the measurement light L21 irradiated from the measurement light source 210 of the distance measuring unit 20, the reflected light L22, and the first detection light L31 emitted by the first projector 310 of the detection unit 30. The distance measuring unit 20 described later is disposed so as to be surrounded by the optical window 125.

[0016] In this embodiment, the optical window 125 is removable in the lidar device 1. Specifically, the second case body 120 including the optical window 125 can be separated from the first case body 110. The removal of the optical window 125 will be described later.

[0017] The distance measurement unit 20 measures the distance to an object that reflects the measurement light L21 using the measurement light L21. The distance measurement unit 20 is housed in the second case body 120. The distance measurement unit 20 is rotatable about the central axis of the substantially frustum-shaped portion of the second case body 120. The central axis is omitted in FIG. 1. Note that the position of the distance measurement unit 20 in the second case body 120 is not limited to the position shown in FIG. 1. The distance measurement unit 20 is controlled by the control unit 350. The distance measurement unit 20 includes a measurement light source 210 and a measurement light receiving unit 220.

[0018] The measurement light source 210 irradiates the measurement light L21 toward the optical window 125 according to the control of the control unit 350. The irradiated measurement light L21 passes through the optical window 125. The measurement light L21 that has passed through the optical window 125 reaches an object (not shown). The measurement light source 210 may be, for example, a semiconductor laser. The measurement light receiving unit 220 receives the reflected light L22 that is reflected from the object and passes through the optical window 125. As described above, the distance measurement unit 20 is rotatable about the central axis of the substantially frustum-shaped portion of the second case body 120. Therefore, the distance measurement unit 20 can irradiate the measurement light L21 in various directions and receive the reflected light L22 from objects in various directions. The measurement light receiving unit 220 is, for example, a photodiode. Hereinafter, the photodiode will be referred to as PD.

[0019] The detection unit 30 detects the contamination of the optical window 125. The detection unit 30 includes seven first light emitters 310, a second light emitter 320, a light receiver 330, a reflector 340, and a control unit 350. In FIG. 1, one of the seven first light emitters 310 is shown. For example, as shown in FIG. 5, the control unit 350 may be implemented by a processor 351 such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and a memory 352 such as a RAM (Random Access Memory) or a ROM (Read Only Memory).

[0020] The first light emitter 310 emits a first detection light L31 that passes through the optical window 125. The first light emitter 310 is housed in the first case body 110. In the present embodiment, the first light emitter 310 may be a light emitting diode (hereinafter referred to as an LED). The second light emitter 320 emits a second detection light L32 that does not pass through the optical window 125. The second light emitter 320 is housed in the first case body 110. In the present embodiment, the second light emitter 320 may be an LED.

[0021] The light receiver 330 receives the first detection light L31 and the second detection light L32 reflected by the reflector 340. In the light receiver 330, a voltage corresponding to the intensity of the received first detection light L31 and a voltage corresponding to the intensity of the second detection light L32 are generated. The voltage generated in the light receiver 330 is also referred to as an output voltage. The light receiver 330 includes seven first light receivers 331 and one second light receiver 332. In FIG. 1, one of the seven first light receivers 331 is shown.

[0022] The first light receiver 331 receives the first detection light L31 reflected by the reflector 340. In the first light receiver 331, a voltage corresponding to the intensity of the received first detection light L31 is generated. The first light receiver 331 may be a PD. Each of the seven first light receivers 331 is combined with each of the corresponding seven first light emitters 310. That is, the first detection light L31 emitted by one of the seven first light emitters 310 is received by the corresponding one of the seven first light receivers 331. There are seven combinations of the first light emitter 310 and the first light receiver 331. The combination of the first light emitter 310 and the first light receiver 331 is called the first pair P1. In FIG. 1, one first pair P1 is represented.

[0023] The first pair P1 is housed in the first case body 110. The first pair P1 is arranged at a position where the first detection light L31 can be incident on the reflector 340 and the first detection light L31 reflected by the reflector 340 can be received. The first light emitter 310 and the first light receiver 331 of the first pair P1 are close to each other. For example, the distance between the first light receiver 331 and the second light receiver 332 may be 1 to 2 cm. The seven first pairs P1 are annularly and equally spaced along the end 124 of the flange 123 of the optical window 125 in the first case body 110. For example, each of the first pairs P1 is arranged along a fan-shaped arc centered on the central axis of the second case body 120, and the arrangement interval is an angle of 40 degrees.

[0024] The second light receiver 332 receives the second detection light L32 reflected by the reflector 340. In the second light receiver 332, a voltage corresponding to the intensity of the received second detection light L32 is generated. The second light receiver 332 may be a PD. The second light receiver 332 is combined with the second light emitter 320. That is, the second detection light L32 emitted by the second light emitter 320 is received by the second light receiver 332. The combination of the second light emitter 320 and the second light receiver 332 is called the second pair P2.

[0025] The second pair P2 is housed in the first case body 110. The second pair P2 is disposed at a position where the second detection light L32 can be incident on the reflector 340 and the reflected second detection light L32 can be received. The second projector 320 and the second light receiver 332 of the second pair P2 are close to each other. For example, the distance between the second projector 320 and the second light receiver 332 may be 1 to 2 cm. The second pair P2 is close to the first pair P1. For example, the distances between the second pair P2 and each first pair P1 are each 1 to 2 centimeters. The distance between the second pair P2 and the first pair P1 is the straight-line distance between the first light receiver 331 and the second projector 320. Since the seven first light receivers 331 and one second light receiver 332 are arranged adjacent to each other in the first case body 110, the temperature of the environment in which they are arranged is substantially the same. In other words, they are arranged so that the temperature of the environment in which the seven first light receivers 331 and one second light receiver 332 are arranged is substantially the same. By providing the light receiver 330 with the first light receiver 331 and the second light receiver 332, the degree of freedom in arranging the light receiver 330 in the case 10 is higher as compared with the case where one light receiving element (i.e., the light receiver) receives the first detection light L31 and the second detection light L32. Also, compared with the above case, the processing of the control unit 350 can be simplified. For example, when one light receiver receives two detection lights, it is necessary to distinguish the detection lights received by the light receiver in order to measure the output voltage of each detection light. Therefore, the control unit 350 is required to control, for example, the emission timing of the detection light. However, according to the detection unit 30 according to the present embodiment, since a plurality of light receivers receive the corresponding detection lights, the processing for distinguishing the above-described detection lights (for example, the processing for controlling the emission timing of the detection light) becomes unnecessary.

[0026] The reflector 340 reflects the first detection light L31 that has passed through the optical window 125 and the second detection light L32 that has not passed through the optical window 125. The reflector 340 is the upper surface 122 of the second case body 120 and is disposed inside the second case body 120. For example, the shape of the reflector 340 is an annular sector. The central angle of the reflector 340 may be 270 degrees. The center of the arc of the reflector 340 coincides with the center of the second case body 120 (i.e., the upper surface 122).

[0027] In this embodiment, since the reflector 340 is provided, the degree of freedom in the optical paths of the first detection light L31 and the second detection light L32 is higher than that in the case where the reflector 340 is not provided.

[0028] Further, since the reflector 340 is disposed on the upper surface 122 opposite to the opening surface of the second case body 120, it is possible to suppress the attachment of dirt from the outside to the reflector 340 when the second case body 120 is removed. Furthermore, since the shape of the reflector 340 is an annular sector, the reflector 340 can reflect, as a single unit, the plurality of first detection lights L31 emitted by the plurality of first pairs P1 arranged in an annular shape.

[0029] As described above, the components of the detection unit 30 other than the reflector 340 are accommodated in the first case body 110. Compared with the case where the components of the detection unit 30 other than the reflector 340 are dispersedly accommodated in both the first case body 110 and the second case body 120, the power system for supplying power to the detection unit 30 is concentrated in the first case body 110. Therefore, the size of the lidar device 1 can be reduced.

[0030] The optical paths passing through the reflector 340 will be described. The first detection light L31 emitted by the first light emitter 310 of the first pair P1 is incident on the reflector 340. The first detection light L31 incident on the reflector 340 is reflected by the reflector 340. The reflected first detection light L31 is received by the first light receiver 331. The second detection light L32 emitted by the second light emitter 320 of the second pair P2 is incident on the reflector 340. The second detection light L32 incident on the reflector 340 is reflected by the reflector 340. The reflected second detection light L32 is received by the second light receiver 332.

[0031] The control unit 350 detects the contamination of the optical window 125 based on the value of the output voltage of the light receiver 330. Specifically, the control unit 350 corrects the value of the output voltage of the first detection light L31 based on the deviation between the value of the output voltage of the second detection light L32 and a predetermined reference value. The control unit 350 detects the contamination of the optical window 125 based on the corrected value of the output voltage of the first detection light L31. Details of the correction will be described later.

[0032] Also, in the present embodiment, the control unit 350 calculates the distance between the lidar device 1 and the object based on the reflected light L22 received by the distance measurement unit 20. As described above, the measurement light L21 irradiated by the measurement light source 210 passes through the optical window 125 and exits the lidar device 1. The measurement light L21 is reflected by the object, and the reflected light L22, which is the reflected measurement light, passes through the optical window 125 and is received by the measurement light receiving unit 220. Due to the passage of time from when the measurement light L21 is irradiated until the reflected light L22 is received by the measurement light receiving unit 220, a phase difference occurs between the irradiated measurement light L21 and the received reflected light L22. The control unit 350 calculates the distance based on the phase difference.

[0033] A2. Correction of the value of the output voltage of the first detection light L31 by the control unit 350 and detection of contamination of the optical window 125 It is known that the outputs of the LED and the PD depend on the temperature of the environment in which the LED and the PD are arranged. For example, the intensity of the light emitted by the LED decreases as the ambient temperature rises. The voltage generated in the PD (i.e., the output voltage) increases as the ambient temperature rises. Furthermore, the inventor has found that when a specific LED is used as the light source and a specific PD is used as the light receiving element, the value of the output voltage of the PD decreases as the ambient temperature rises. The inventor has also found that the value of the output voltage of the PD increases as the ambient temperature drops.

[0034] In this embodiment, a combination of an LED and a PD in which the correlation between temperature and output voltage is negative is selected. The LEDs used as the first light emitter 310 and the second light emitter 320 have substantially the same characteristics with respect to temperature. The PDs used as the first light receiver 331 and the second light receiver 332 have substantially the same characteristics with respect to temperature.

[0035] The correction of the value of the output voltage of the first detection light L31 by the control unit 350 in this embodiment will be described. In this embodiment, the value of the output voltage of the second light receiver 332 that has received the detection light emitted at a predetermined intensity by the second light emitter 320 in a state where the lidar device 1 is arranged in an environment of 25°C is stored in the control unit 350 by the user as a predetermined reference value for a light reception intensity of 100%.

[0036] FIG. 2 is a diagram for explaining the difference in the light reception intensity of the second light receiver 332 and the difference in the light reception intensity of the corrected first light receiver 331. FIG. 2 is based on the light reception intensity at 25°C and represents the difference between the light reception intensity at each temperature and the light reception intensity at 25°C. Specifically, FIG. 2 represents the difference between the light reception intensity in an environment of -10°C and 65°C and the light reception intensity at 25°C, respectively. The difference in the light reception intensity of the second light receiver 332 is the difference between the light reception intensity of the second light receiver 332 at each temperature and the light reception intensity of the second light receiver 332 at 25°C (i.e., the light reception intensity corresponding to the reference value). As described above, the characteristics of the first light receiver 331 and the second light receiver 332 with respect to temperature are substantially the same. Therefore, the difference in the light reception intensity of the second light receiver 332 can be regarded as the difference between the light reception intensity of the first light receiver 331 at each temperature and the light reception intensity of the first light receiver 331 at 25°C. The difference in the light reception intensity of the corrected first light receiver 331 is the difference between the light reception intensity of the first light receiver 331 corresponding to the corrected output voltage at each temperature and the light reception intensity of the second light receiver 332 at 25°C (i.e., the light reception intensity of the first light receiver 331 at 25°C).

[0037] Next, the correction by the control unit 350 in an environment of 65°C will be described. As shown in FIG. 1, the second light projector 320 emits the second detection light L32 according to the instruction of the control unit 350, and the second light receiver 332 receives the second detection light L32. In the second light receiver 332, an output voltage corresponding to the intensity of the received second detection light L32 is generated. The control unit 350 calculates the light reception intensity of the second light receiver 332 from the value of the output voltage generated in the second light receiver 332 and a predetermined reference value. For example, as shown in FIG. 2, the light reception intensity (i.e., 90%) of the second light receiver 332 in an environment where the temperature is 65°C is calculated, and this light reception intensity is 10% lower than the light reception intensity (i.e., 100%) of the second light receiver 332 at 25°C. At this time, the light reception intensity of the first light receiver 331 is also considered to be 10% lower than the light reception intensity of the second light receiver 332 at 25°C.

[0038] Next, the first light projector 310 emits the first detection light L31 according to the instruction of the control unit 350, and the first light receiver 331 receives the first detection light L31 (see FIG. 1). Note that the timing at which the first light receiver 331 receives the first detection light L31 (i.e., the timing at which the first light projector 310 emits the first detection light L31) and the timing at which the second light receiver 332 receives the second detection light L32 (i.e., the timing at which the second light projector 320 emits the second detection light L32) may be different or may be the same.

[0039] Here, assume a case where no correction is performed. As described above, the light reception intensity of the first light receiver 331 in an environment of 65°C decreases by 10% compared to the environment of 25°C. In this case, even when there is no dirt on the optical window 125, the control unit 350 may detect dirt on the optical window 125 due to the decrease in light reception intensity caused by the high temperature. As a result, for example, the user may be requested to perform unnecessary cleaning of the optical window 125 by a notification based on the instruction of the control unit 350.

[0040] The correction of the output voltage value of the first detection light L31 will be described. Specifically, the control unit 350 multiplies the output voltage value of the first detection light L31 by a numerical value obtained by dividing the light reception intensity corresponding to a predetermined reference value by the light reception intensity of the second detection light L32. For example, the control unit 350 multiplies the output voltage value of the first detection light L31 by a value obtained by dividing 100% (the light reception intensity corresponding to the predetermined reference value) by 90% (the light reception intensity of the second light receiver 332). Thereby, the output voltage value of the first detection light L31 is corrected for a 10% decrease. In this way, the output voltage value of the first detection light L31 in an environment of 65°C is corrected. The control unit 350 detects the contamination of the optical window 125 based on the corrected output voltage value of the first detection light L31. Specifically, the control unit 350 detects the contamination of the optical window 125 based on the ratio between the corrected output voltage value of the first detection light L31 and a predetermined reference value.

[0041] Next, the correction by the control unit 350 in an environment of -10°C will be described. As shown in FIG. 2, in an environment of -10°C, the light reception intensity of the second light receiver 332 is 10% higher than the light reception intensity of the second light receiver 332 at 25°C. In contrast, the control unit 350 corrects the output voltage value of the first detection light L31 based on the output voltage value of the second light receiver 332 and the reference value, similar to the correction in the environment of 65°C described above. Note that if the light reception intensity (i.e., the output voltage) becomes too high, the control unit 350 may determine that the lidar device 1 is not operating normally and may stop the operation of the lidar device 1. Also, although FIG. 2 shows examples of -10°C and 65°C, the temperatures for which correction is possible are not limited to these temperatures. Correction is possible in a temperature range wider than or narrower than the range including these temperatures.

[0042] In FIG. 2, the difference in the light reception intensity of the corrected first light receiver 331 at each temperature is 0%. However, due to the environment in which the first light receiver 331 and the second light receiver 332 are arranged and the characteristics of the PD, the difference in the light reception intensity of the corrected first light receiver 331 may be a value other than 0%. In that case, the control unit 350 may perform additional correction. For example, when the light reception intensity of the corrected first light receiver 331 at 65° C. is +3%, +3% is stored in the control unit 350 by the user as an additional correction value. The control unit 350 corrects the value of the output voltage of the first detection light L31 so that +3% becomes 0% using the stored additional correction value. Note that the above additional correction may be performed simultaneously with the correction due to the temperature described above.

[0043] In the present embodiment, the second detection light L32 does not pass through the optical window 125 and is received by the light receiver 330. Therefore, the value of the output voltage of the second detection light L32 is not affected by the contamination of the optical window 125. The contamination of the optical window 125 is detected based on the value of the output voltage of the second detection light L32 and the value of the output voltage of the first detection light L31 corrected based on a predetermined reference value. Thereby, even when the temperature of the environment in which the lidar device 1 is arranged changes, in the lidar device 1, false detection and non-detection of the contamination of the optical window 125 can be reduced. As a result, it is possible to suppress the distance measurement unit 20 from erroneously measuring the distance between the lidar device 1 and an object. Further, it is possible to suppress the user from being requested to unnecessarily clean the optical window 125 by a notification based on an instruction from the control unit 350.

[0044] In the present embodiment, the contamination at different positions on the optical window 125 is detected by a plurality of first pairs P1. Therefore, compared with the case where the lidar device 1 includes only one set of the first pair P1, it is possible to detect the contamination at a plurality of positions on the optical window 125. Thereby, when the distance measurement unit 20 measures the distance in a plurality of directions, it is possible to suppress the erroneous measurement of the distance in a plurality of directions.

[0045] A3. Display indicating that the optical window 125 is dirty In this embodiment, when the value of the output voltage of the corrected first detection light L31 is smaller than a predetermined numerical value, the control unit 350 causes the monitor 111 to display that the optical window 125 is dirty. In other words, when the value of the output voltage of the corrected first detection light L31 is smaller than the threshold value, the control unit 350 outputs a detection signal for the dirt of the optical window 125. The predetermined numerical value is an arbitrary numerical value stored in the control unit 350 by the user. When the value of the output voltage of the corrected first detection light L31 is smaller than this numerical value, the control unit 350 causes the monitor 111 to output a screen warning the user that it is necessary to clean the optical window 125. Thereby, the user can know the timing to clean the optical window 125.

[0046] A4. Detection of the removal of the optical window 125 FIG. 3 is a schematic diagram for explaining a state where the optical window 125 is not located within a predetermined range RE. In this embodiment, the control unit 350 can detect that the optical window 125 is not located within the predetermined range RE by using the second pair P2. The second case body 120 including the optical window 125 can be separated from the first case body 110 by the user for replacement or cleaning. That is, the second case body 120 is detachable from the first case body 110. For example, the second case body 120 is separated as indicated by the arrow AR in FIG. 3. However, the second case body 120 may be separated from the first case body 110 without the intention of the user.

[0047] When the second case body 120 is separated from the first case body 110, the value of the output voltage of the second detection light L32 reflected by the reflector 340 becomes smaller. In the present embodiment, when the value of the output voltage of the second detection light L32 is smaller than a predetermined threshold value, the control unit 350 outputs that the optical window 125 is not located within a predetermined range RE. The predetermined threshold value is the minimum value of the value of the output voltage generated in the second light receiver 332 that receives the second detection light L32. The predetermined range RE is, for example, the range from the lower end (e.g., the flange 123) to the upper end (e.g., the upper surface 122) of the optical window 125 in a state where the second case body 120 is connected to the first case body 110.

[0048] For example, when the value of the output voltage of the second detection light L32 is smaller than a predetermined threshold value, the control unit 350 outputs an error signal to the monitor 111. That is, the control unit 350 detects that the optical window 125 has been removed. The monitor 111 displays that the optical window 125 is not located within the predetermined range RE based on the error signal. Thereby, the user can know that the optical window 125 is not located within the predetermined range RE. That is, the user can know that the second case body 120 is separated from the first case body 110.

[0049] B. Second Embodiment FIG. 4 is a schematic diagram for explaining the configuration of the lidar device 1 according to the second embodiment. In the second embodiment, different from the first embodiment, one light receiver receives the first detection light L31 and the second detection light L32. Since the other configurations and processes are the same as those in the first embodiment, the same reference numerals are given and detailed descriptions are omitted.

[0050] As shown in FIG. 4, in the present embodiment, the lidar device 1 includes seven first light emitters 310, one second light emitter 320, and seven light receivers 333. The light receiver 333 operates as the light receiver 330. In the first embodiment, the first light receiver 331 receives the first detection light L31, and the second light receiver 332 receives the second detection light L32. In the second embodiment, as shown in FIG. 4, the light receiver 333 receives the first detection light L31 and the second detection light L32. Note that the second detection light L32 may be received by any of the seven light receivers 333.

[0051] In the second embodiment, the control unit 350 controls the light receiver 333 to receive the first detection light L31 and the second detection light L32 at different timings. First, the control unit 350 causes the second light emitter 320 to emit light, and the second detection light L32 is received by the light receiver 333, and an output voltage is generated at the light receiver 333. The control unit 350 stores the value of the output voltage generated at the light receiver 333. Next, the control unit 350 causes the first light emitter 310 to emit light, and the first detection light L31 is received by the light receiver 333, and an output voltage is generated at the light receiver 333. The control unit 350 corrects the output voltage of the first detection light L31 based on the stored output voltage of the second detection light L32 and a reference value. The correction process is the same as that in the first embodiment, so the description is omitted. Thereby, similar to the first embodiment, the control unit 350 detects the contamination of the optical window 125.

[0052] Thus, according to the second embodiment, compared with the case where different light receivers receive the first detection light L31 and the second detection light L32 as in the first embodiment, the components of the lidar device 1 can be reduced, and the size of the lidar device 1 can be reduced.

[0053] C. Other Embodiments (C1-1) In the above embodiment, the value of the output voltage corresponding to the light reception intensity of the second light receiver 332 in an environment of 25°C is stored in the control unit 350 by the user as a predetermined reference value. However, depending on the characteristics of the first light projector 310, the second light projector 320, and the light receiver 330, for example, the value of the output voltage corresponding to the light reception intensity at a temperature other than 25°C, such as 27°C or 30°C, may be used as the predetermined reference value.

[0054] (C1-2) The value of the output voltage corresponding to the light reception intensity measured in a state where the second light projector 320 and the light receiver 330 are arranged outside the lidar device 1 may be used as a predetermined reference value.

[0055] (C1-3) In the above embodiment, the control unit 350 corrects the value of the output voltage of the first detection light L31 based on the ratio of the value of the output voltage of the second detection light L32 and a predetermined reference value. However, the control unit 350 may correct the value of the output voltage of the first detection light L31 based on the difference between the value of the output voltage of the second detection light L32 and a predetermined reference value.

[0056] (C1-4) In the above embodiment, the control unit 350 detects the dirt on the optical window 125 based on the difference between the value of the output voltage of the corrected first detection light L31 and the value of the output voltage of the second detection light L32 at 25°C. However, the control unit 350 may detect the dirt on the optical window 125 based on the difference between the value of the output voltage of the corrected first detection light L31 and the value of the output voltage of the first detection light L31 at 25°C. The value of the output voltage of the first detection light L31 at 25°C is measured in a state where there is no dirt on the optical window 125 and is stored in the control unit 350 in advance.

[0057] (C1-5) In the above embodiment, LEDs are used as the first light emitter 310 and the second light emitter 320, and PDs are used as the first light receiver 331 and the second light receiver 332. However, light sources other than LEDs may be used as the first light emitter 310 and the second light emitter 320. For example, the light source other than the LED may be an SLD (Super Luminescent Diode), an LD (Laser Diode), or an infrared light source. Further, the light receiving element of the light receiver 330 may be an avalanche photodiode. By setting a reference value according to the characteristics of each combination of the light source and the light receiving element with respect to temperature, the output voltage of the first detection light L31 can be corrected according to the characteristics.

[0058] (C1-6) An optical window inspection apparatus including the detection unit 30 and the case 10 except for the distance measurement unit 20 may be formed.

[0059] (C2-1) In the above embodiment, the lidar device 1 includes seven first light emitters 310 and seven first light receivers 331. However, the number of the first light emitters 310 and the first light receivers 331 may each be one, or may be other than seven such as four or five. The lidar device 1 can include a plurality of first light emitters 310 and a plurality of first light receivers 331. Further, the number of the first light emitters 310 and the number of the first light receivers 331 may be different. A part of the plurality of first light emitters 310 and the plurality of first light receivers 331 may not be used.

[0060] (C2-2) In the above embodiment, the distance between the first light emitter 310 and the first light receiver 331 is 1 to 2 cm, the distance between the second light emitter 320 and the second light receiver 332 is 1 to 2 cm, and the distance between the second pair P2 and each first pair P1 is 1 to 2 cm, respectively. However, these distances may be different from 1 to 2 cm, such as 0.5 cm, 3 cm, or 5 cm, for example. The first light receiver and the second light receiver are arranged adjacent to the first case body 110 so that the temperatures of the environments where the first light receiver and the second light receiver are arranged are substantially the same.

[0061] (C3-1) In the above-described embodiment, the control unit 350 corrects the value of the output voltage of the first detection light L31 and detects the contamination of the optical window 125 using the corrected output voltage value. However, the control unit 350 may correct the threshold value used in the contamination detection process of the optical window 125 and detect the contamination of the optical window 125 using the corrected threshold value. Specifically, the control unit 350 corrects the threshold value used in the contamination detection process of the optical window 125 based on the value of the output voltage of the second detection light L32 and a predetermined reference value, and detects the contamination of the optical window 125 based on the value of the output voltage of the first detection light L31 and the corrected threshold value. For example, the threshold value used in the contamination detection process is the predetermined numerical value described in A3 above. Thus, even if the threshold value used in the contamination detection process is corrected instead of correcting the value of the output voltage of the first detection light L31, a similar effect is obtained.

[0062] (C4-1) In the above-described embodiment, the detection unit 30 includes the reflector 340. However, the detection unit 30 may not include the reflector 340. In this case, the first light projector 310 and the second light projector 320 respectively emit the first detection light L31 and the second detection light L32 toward the light receiver 330. The light receiver 330 directly receives the first detection light L31 and the second detection light L32 from the first light projector 310 and the second light projector 320, respectively.

[0063] (C5-1) In the above-described embodiment, the first case body 110 houses the components of the detection unit 30 other than the reflector 340, and the second case body 120 houses the reflector 340. However, the second case body 120 may house the reflector 340 and the control unit 350, and the first case body 110 may house the components of the detection unit 30 other than the reflector 340 and the control unit 350.

[0064] (C5-2) In the above-described embodiment, the shape of the first case body 110 is a substantially rectangular parallelepiped. However, the shape of the first case body 110 may be a shape other than a substantially rectangular parallelepiped, such as a substantially cylindrical shape or a substantially triangular prism shape.

[0065] (C5-3) In the above-described embodiment, a part of the shape of the second case body 120 is a substantially frustum of a cone. However, a part of the shape of the second case body 120 may be other shapes such as a substantially cylinder or a substantially rectangular parallelepiped.

[0066] (C5-4) In the above-described embodiment, the side surface 121 and the flange 123 of the second case body 120 are formed by the optical window 125. However, only a part of the side surface 121 and a part of the flange 123 of the second case body 120 may be formed by the optical window 125.

[0067] (C6-1) In the above-described embodiment, the shape of the reflector 340 is an annular sector with a central angle of 270 degrees. However, the central angle of the reflector 340 may be an angle other than 270 degrees such as 240 degrees or 260 degrees. For example, the reflector 340 may be an annular sector with a central angle of 180 degrees. Also, the detection unit 30 may include a plurality of reflectors 340. For example, the plurality of reflectors 340 may be seven reflectors having a substantially rectangular parallelepiped shape. When the detection unit 30 includes a plurality of reflectors 340, the shapes of the plurality of reflectors 340 may be different from each other. In this case, the first detection light L31 and the second detection light L32 may be reflected by any of the plurality of reflectors 340.

[0068] (C7-1) In the above-described embodiment, the optical window 125 is removable. However, the optical window 125 may be non-removable when the first case body 110 and the second case body 120 are integrally formed.

[0069] (C7-2) In the above-described embodiment, when the value of the output voltage of the second detection light L32 is smaller than a predetermined threshold value, the control unit 350 outputs that the optical window 125 is not located within a predetermined range RE. However, when the optical window 125 is non-removable, the control unit 350 does not need to determine whether the optical window 125 is located within a predetermined range. In this case, an output indicating that the optical window 125 is not located within a predetermined range is not performed either.

[0070] (C8-1) In the above embodiment, the first case body 110 includes the monitor 111. However, the first case body 110 may not include the monitor 111. Further, even if the first case body 110 includes the monitor 111, the control unit 350 may not cause the monitor 111 to display that the optical window is dirty.

[0071] (C9-1) In the above embodiment, the control unit 350 calculates the distance between the lidar device 1 and the object based on the phase difference generated between the measurement light L21 and the reflected light L22. However, the control unit 350 may calculate the distance based on the time from when the measurement light L21 is irradiated until the reflected light L22 is received. For example, the measurement light source 210 irradiates the pulsed measurement light L21, and the measurement light receiving unit 220 receives the reflected light L22 from the object. The control unit 350 calculates the above distance based on the time from the irradiation of the measurement light L21 to the reception of the reflected light L22.

[0072] (C9-2) In the above embodiment, the control unit 350 controls the distance measurement unit 20 and the detection unit 30. However, the lidar device 1 may include a control unit different from the control unit 350, and the different control unit may control the distance measurement unit 20.

[0073] (C9-3) In the above embodiment, the measurement light source 210 is a semiconductor laser, and the measurement light receiving unit 220 is a PD. However, the measurement light source 210 may be a laser other than a semiconductor laser such as a solid-state laser or a gas laser. Further, the measurement light receiving unit 220 may be an avalanche photodiode.

[0074] (C10-1) In the above embodiment, the combination of the seven first light emitters 310 and the first light receivers 331 is arranged at equal intervals along the optical window 125. However, the combination of the seven first light emitters 310 and the first light receivers 331 may not be arranged at equal intervals. For example, the arrangement interval between two certain combinations may be 60 degrees, and the arrangement interval between another two combinations may be 40 degrees.

[0075] In the above embodiment, the plurality of first pairs P1 are arranged at intervals of 40 degrees. However, the arrangement intervals of the plurality of first pairs P1 may be angles other than 40 degrees, such as 30 degrees or 50 degrees.

[0076] The present disclosure is not limited to the above-described embodiments, examples, and modifications, and can be realized in various configurations without departing from the gist thereof. For example, some of the configurations in the above-described embodiments, examples, and modifications may be appropriately replaced, combined, or deleted within the range of solving the above-described problems or achieving the above-described effects.

Claims

1. A first light projector that emits a first detection light that passes through an optical window that transmits incident light, a second light projector that emits a second detection light that does not pass through the optical window, a light receiver that receives the first detection light and the second detection light, and in which a first voltage corresponding to the intensity of the received first detection light and a second voltage corresponding to the intensity of the second detection light are generated, a control unit that corrects the value of the first voltage based on the value of the second voltage and a predetermined reference value, and performs a process of detecting the dirt of the optical window based on the corrected value of the first voltage, An optical window inspection device comprising:

2. The light receiver includes a first light receiver and a second light receiver, The first light receiver receives the first detection light, and in the first light receiver, the first voltage is generated, The second light receiver receives the second detection light, and in the second light receiver, the second voltage is generated, The optical window inspection device according to claim 1.

3. The light receiver includes a single light receiver, The first light projector emits the first detection light at a timing different from the timing at which the second light projector emits the second detection light, The optical window inspection device according to claim 1.

4. Furthermore, it includes a reflector that reflects light, The light receiver receives the first detection light reflected by the reflector and the second detection light reflected by the reflector, The optical window inspection device according to any one of claims 1 to 3.

5. The first light projector, the second light projector, the light receiver, and the control unit are housed in a first case body, The reflector is housed in a second case body including the optical window, The first case body is connected to the second case body, The inside of the first case body communicates with the inside of the second case body The optical window inspection device according to claim 4.

6. When the value of the second voltage is smaller than a predetermined threshold value, the control unit outputs an error signal regarding the position of the optical window, The optical window inspection device according to any one of claims 1 to 3.

7. When the corrected value of the first voltage is smaller than a predetermined threshold value, the control unit outputs a detection signal for the dirt of the optical window, The optical window inspection device according to any one of claims 1 to 3.

8. The optical window inspection device according to any one of claims 1 to 3, a case including the optical window, A distance measuring unit that irradiates measurement light that passes through the optical window and receives the reflected light of the measurement light; comprising; the case incorporates the optical window inspection device and the distance measuring unit laser radar device.

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