Distance measuring device

Abstract

Distance measuring device (1) comprising: a transmitting section (10) configured to emit a transmitting wave; a receiving section (30) configured to detect a reflection wave from an object irradiated with the transmitting wave; a mirror module (21) comprising a pair of deflecting mirrors (211, 212) which deflect the transmitting wave and the reflection wave in one direction according to a rotation angle of a reflective surface, and a mirror carrier (213) which supports the pair of deflecting mirrors by being arranged between the pair of deflecting mirrors and is configured to rotate according to the drive of a motor (24);Dividing plates (22, 23), which are plate-like elements provided to divide the pair of deflecting mirrors into two sections, transmit deflecting section (20a), which is a section located on the transmit section side, and receive deflecting section (20b), which is a section located on the receive section side, and which are configured to rotate in an integrated manner with the mirror module; a housing (100) configured to accommodate the transmit section, the receive section, the mirror module, and the separating plates;and a transparent window (200) provided at an opening of the housing, which allows the transmitting wave and the reflected wave to pass through, each of the pair of deflecting mirrors having shielding sections (214a, 214b) by which the transmission of the transmitting waves is suppressed, on at least one of the side surfaces, the side surface which is closer to the transparent window in a state in which the reflective surface is directed towards the transmitting section, of both side surfaces which are arranged about an axis of rotation on the transmitting deflecting section, or the side surface which is farther from the transparent window in a state in which the reflective surface is directed towards the receiving section, of both side surfaces which are arranged about the axis of rotation on the receiving deflecting section.

Description

[Technical Field]The present invention relates to a distance measuring device or distance measuring device having a deflection mirror.[Prior Art]There is a distance measurement device that radiates a transmission wave, detects a reflection wave of the radiated transmission wave from an object, and detects a distance to the object. The distance measurement device includes a housing, and a transmissive window is provided at a portion of the housing through which a transmission wave emitted from inside to outside the housing and a reflection wave entering from outside to inside the housing can pass.Further, a deflection mirror which is rotationally driven is used on the distance measuring apparatus to perform deflection scanning for a transmission wave, and a transmission wave output from a transmission section is reflected on the deflection mirror and emitted in a direction according to a rotation angle of the deflection mirror via the transmissive window. The reflection wave of the transmission wave from an object passes through the transmissive window, is reflected at the reflecting mirror, and is detected at a receiving portion.JP 2018-500 603 A discloses a technique for separating a deflection mirror into a region on a transmitting portion side and a region on a receiving portion side in a lidar device that performs deflection scanning for light. On the lidar device, a transmission beam and a reflection beam are deflected using the same deflection mirror, and thus a partition wall is provided on a reflection surface of the deflection mirror to prevent an optical short circuit between the transmission section side and the reception section side.Reference is also made to DE 10 2014 118 974 A1, CN 2 07 623 512 U, DE 10 2016 114 064 A1 and EP 2 975 447 A1, which were determined as prior art.[Summary of the Invention]However, the inventor has found the following problems as a result of detailed observation.There is a case in which, when a transmission wave reflected at a reflecting mirror passes through a transmissive window, a part of the transmission wave becomes a returning light by being reflected at the transmissive window and returns to the reflecting mirror without being emitted to the outside of the housing.For example, while the reflecting mirror has a configuration in which an element that allows a transmission wave and a reflection wave to pass therethrough is used as a base, and a film that reflects a transmission wave and a reflection wave is provided on a reflection surface, there may be a configuration in which the film is not provided on a side surface. In a case of such a configuration, in a case where a returning light is incident on the side surface of the reflecting mirror, the returning light enters an interior of the reflecting mirror from the side surface.In a case where a transmission wave and a reflection wave are redirected using the same redirecting mirror as in JP 2018-500 603 A, there is a possibility that a returning light that may enter an interior from the side surface at a portion on a transmission portion side of the redirecting mirror is detected at a receiving portion. In other words, there is a case where the returning light is detected at the receiving portion by passing along the inside of the reflecting mirror and is outputted from the side surface at a portion on the receiving portion side. In this way, even when the reflecting mirror is separated into a portion on the transmitting portion side and a portion on the receiving portion side by a partition wall, there is a case where a ghost image, which is an object detected although the object does not actually exist, may occur due to a returning light incident from the side surface of the reflecting mirror.An object of the present invention is directed to reducing the occurrence of ghost images due to a return light.The object is achieved by the subject matter of independent claim 1.One aspect of the present invention is a distance measurement device including a transmitting portion, a receiving portion, a mirror module, partition plates, a housing, and a transmissive window. The transmission section is configured to output a transmission wave. The receiving section is configured to detect a reflection wave from an object irradiated with the transmission wave. The mirror module includes a pair of reflecting mirrors that deflect the transmission wave and the reflection wave in a direction according to a rotation angle of a reflection surface, and a mirror support that supports the pair of reflecting mirrors by being disposed between the pair of reflecting mirrors, and is configured to rotate according to driving of a motor. The separation plates, which are plate-like members provided to divide the pair of deflection mirrors into two portions, transmission deflection portion, which is a portion located on the transmission portion side, and reception deflection portion, which is a portion located on the reception portion side, are configured to rotate integrally with the mirror module. The housing accommodates the transmitting portion, the receiving portion, the mirror module, and the partition plates. The transmissive window is provided at an opening of the housing and allows the transmission wave and the reflection wave to pass therethrough. Each of the pair of reflecting mirrors has shielding portions by which transmission waves are suppressed from passing through, on at least one of the side surfaces, side surface that is closer to the transmissive window in a state in which a reflecting surface faces the transmitting portion, from both side surfaces that are disposed on the transmitting deviating portion via a rotation axis, or side surface that is farther from the transmissive window in a state in which a reflecting surface faces the receiving portion, from both side surfaces that are disposed on the receiving deviating portion via the rotation axis.According to such a configuration, it is possible to reduce occurrence of ghost images due to returning light.[Brief Description of the Figures]FIG. 1 is a perspective view illustrating the appearance of a lidar device; FIG. 2 is an exploded perspective view of the lidar device; FIG. 3 is a perspective view illustrating a configuration of an optical sensing module to be accommodated in a housing of the lidar device; FIG. 4 is a view of a mirror module viewed from a side surface; FIG. 5 is a view of the mirror module viewed from a reflecting surface; FIG. 6 is a schematic diagram illustrating an optical path in a case where a returning light is incident on a reflection surface of a projection light deviating portion; and FIG. 7 is a schematic diagram illustrating an optical path in a case where a returning light is incident on a side surface of the projection light deviating portion.[Description of Embodiments]An exemplary embodiment of the present invention will be described below with reference to the figures.[1. Configuration]A lidar device 1 illustrated in FIG. 1 is a distance measurement device that measures a distance to an object by emitting light and receiving reflection light of the light. The lidar device 1 is used by being mounted on a vehicle, and is used to detect various objects present in front of the vehicle. The lidar is also expressed as a lidar. LIDAR is an abbreviation for light detection and ranging.As illustrated in FIG. 1, the lidar device 1 includes a housing 100 and an optical window 200. The housing 100 is a resin box formed in a rectangular parallelepiped shape having an open area.Hereinafter, a direction along a longer direction of a substantially rectangular opening of the housing 100 is referred to as an X-axis direction, a direction along a shorter direction of the opening is referred to as a Y-axis direction, and a direction orthogonal to an X-Y plane is referred to as a Z-axis direction. Note that right and left in the X-axis direction and up and down in the Y-axis direction are defined by the lidar device 1 viewed from the opening side of the housing 100 in a state where the lidar device 1 is provided on a vehicle such that the X-Z plane becomes horizontal. Further, with respect to the front and rear sides in the Z-axis direction, the opening side of the housing 100 is defined as the front side, and a depth side is defined as the rear side.As shown in FIG. 2, an optical detection module 2 is accommodated inside the housing 100. The optical detection module 2 includes a projection section 10, a scanning section 20, and a light receiving section 30.A configuration of the optical detection module 2 will be described in detail below.[2. Sensing Section]As illustrated in FIG. 3, the sensing section 20 includes a mirror module 21, a pair of partition plates 22 and 23, and a motor 24. the mirror module 21 is provided to stand on the motor 24, and the mirror module 21 and the pair of partition plates 22 and 23 fixed to the mirror module 21 rotate about a rotation axis indicated by a dot-and-dash line in FIGS. 4 and 5 according to driving of the motor 24.The mirror module 21 includes a pair of reflecting mirrors 211 and 212 and a mirror support 213.The pair of reflecting mirrors 211 and 212 are both plate-like elements having reflecting surfaces which reflect light, respectively.The mirror support 213 includes a disc portion 213 aand an installation portion 213 b. The disk portion 213 ais a circular plate-like portion, and a center of the circle is fixed to the rotation axis of the motor 24. The installation portion 213 bis a plate-like portion on both sides of which the pair of reflecting mirrors 211 and 212 is provided, and is provided so as to stand on a circular surface of the disk portion 213 a. A shape of surfaces on which the pair of reflecting mirrors 211 and 212 is provided on the installation portion 213 bcorresponds to a shape of the pair of reflecting mirrors 211 and 212.Note that the pair of reflecting mirrors 211 and 212 have a shape in which two rectangles having different widths are integrated in a longer direction. Specifically, the pair of reflecting mirrors 211 and 212 has a shape in which a first rectangle and a second rectangle having a longer width in the longer direction than a width of the first rectangle are aligned and integrated along a center axis that extends along shorter directions of the respective rectangles. Hereinafter, a portion corresponding to the first rectangle is referred to as a narrow portion, and a portion corresponding to the second rectangle is referred to as a wide portion on the pair of reflecting mirrors 211 and 212.The pair of reflecting mirrors 211 and 212 integrated via the installation portion 213 bis provided so as to stand on the disk portion 213 asuch that the wide portion is disposed on the lower side and a position of the center axis coincides with a center of the circle of the disk portion 213 ain a state where the pair of reflecting mirrors 211 and 212 is integrated. Thereby, the mirror module 21 rotates about the rotation axis of the motor 24.The pair of separation plates 22 and 23 is obtained by dividing a circular plate-like member having a diameter that is the same as a width in the longer direction of the wide portion of the pair of deflection mirrors 211 and 212 into two semicircular portions. The pair of partition plates 22 and 23 are fixed to the mirror module 21 in a state where the narrow portion of the pair of reflecting mirrors 211 and 212 is interposed between the pair of partition plates 22 and 23 from both sides and in a state where the pair of partition plates 22 and 23 abuts a stepped portion between the wide portion and the narrow portion of the pair of reflecting mirrors 211 and 212.Hereinafter, a portion on an upper side of the pair of separation plates 22 and 23 among the pair of deflection mirrors 211 and 212, that is, a portion on the narrow portion side, is referred to as a projection light deflection portion 20 a, and a portion on a lower side of the pair of separation plates 22 and 23, that is, a portion on the wide portion side, is referred to as a received light deflection portion 20 b.[3. Deflection mirror]The reflecting mirrors 211 and 212 are obtained by forming a reflecting film by evaporating a substance reflecting light on a reflecting surface using a mirror substrate formed with an element allowing light to pass therethrough as a base. While light is reflected on the reflecting surfaces of the reflecting mirrors 211 and 212 with the reflecting film, light passes through side surfaces having no reflecting film.[3-1. Shield Portion]As indicated by shaded portions in FIG. 4, shield portions 214 aand 214 b, which are portions through which light is less likely to pass, are formed on side surfaces of a part of the deflection mirrors 211 and 212. The shield portions 214 aand 214 bare formed by, for example, black ink printed on one surface of the mirror substrate.Positions at which the shield portions 214 aand 214 bare formed will be described with reference to FIGS. 6 and 7. FIGS. 6 and 7 are schematic diagrams, as viewed from above in the Y-axis direction, of a space in which the optical detection module 2 is accommodated inside the housing 100. Note that FIGS. 6 and 7 show the projection section 10 and the projection light deviating section 20 athat are located in the upper space in the Y-axis direction in the space, and do not show the light receiving section 30 and the received light deviating section 20 bthat are located in the lower space. In FIGS. 6 and 7, the reflecting surface of the reflecting mirror 211 is directed in a direction in which the projection portion 10 and the light receiving portion 30 are located.The shielding portion 214 ais formed on each of the reflecting mirrors 211 and 212 on a side surface that is closer to the optical window 200 in a state where the reflection surface faces the projection portion 10, from both side surfaces that are disposed on the projection light deviating portion 20 avia the rotation axis. In FIGS. 6 and 7, the shielding portion 214 aat each of the deflection mirrors 211 and 212 is indicated by a shaded portion on the side surface of the projection light deflection portion 20 a.The shielding portion 214 bis formed on each of the reflecting mirrors 211 and 212 on a side surface farther from the optical window 200 in a state where the reflection surface faces the light receiving portion 30, from both side surfaces disposed on the received light deviating portion 20 bvia the rotation axis. While not illustrated in FIGS. 6 and 7, the shielding portion 214 bon each of the reflecting mirrors 211 and 212 is disposed on a side surface of the received light deviating portion 20 bon an opposite side to the side surface on which the shielding portion 214 ais disposed.[3-2. Low-Reflection Portion]As indicated by shaded portions in FIG. 5, low-reflection portions 215, which are portions that are less likely to reflect light, are formed on a part of the reflection surfaces of the reflecting mirrors 211 and 212. The low-reflection portion 215 is formed by, for example, black ink that is the same as the black ink of the shield portions 214 aand 214 bprinted on the reflection film.A position where the low reflection portion 215 is formed will be described with reference to FIGS. 6 and 7. The low reflection portion 215 is formed on each of the reflecting mirrors 211 and 212 at an end portion of the reflection surface of the projection light deviating portion 20 athat is on the optical window 200 side in a state where the reflection surface faces the projection portion 10. In FIGS. 6 and 7, the low-reflection portion 215 on each of the reflecting mirrors 211 and 212 is indicated by a shaded portion on the reflection surface of the projection light deviating portion 20 a. In other words, the low reflection portion 215 is disposed at an end portion on the same side as the side surface on which the shielding portion 214 ais disposed on the projection light deviating portion 20 a. In a case where the shielding portions 214 aand 214 band the low-reflection portion 215 are formed using the same black ink, the shielding portion 214 aand the low-reflection portion 215 are continuously formed.[4. Projection Section]As illustrated in FIG. 3, the projection section 10 includes a pair of light emitting modules 11 and 12.The light emitting module 11 includes a light source 111 and a light emitting lens 112 arranged to face each other. A semiconductor laser is used as the light source 111. The light emitting lens 112 is a lens that focuses light emitted from the light source 111 to have a narrower beam width. Similarly, the light emitting module 12 includes a light source 121 and a light emitting lens 122. The light emitting module 12 is similar to the light emitting module 11, and thus the description is omitted.The projection rotating light mirror 15 is a mirror that changes a light propagating direction.The light emitting module 11 is arranged such that light output from the light emitting module 11 is directly incident on the projection light deviating portion 20 a.The light emitting module 12 is arranged such that light output from the light emitting module 12 is incident on the projection light deviating portion 20 aafter a propagation direction at the projection light rotating mirror 15 is bent by about 90°.Here, the light emitting module 11 is arranged to output light from left to right in the X-axis direction, and the light emitting module 12 is arranged to output light from back to front in the Z-axis direction. Further, the projection rotating mirror 15 is disposed so as not to block a light path from the light emitting module 11 to the projection light deviating portion 20 a.[5. Light Receiving Portion]The light receiving portion 30 includes a light receiving element 31, and the light receiving portion 30 may include a light receiving lens 32 and a received rotating light mirror 33.The light receiving element 31 includes an APD array in which / the plurality of APDs are arranged in series. APD is an abbreviation for avalanche photodiode.The light receiving lens 32 is a lens that concentrates light coming from the received light deviating portion 20 b.The received light rotating mirror 33 is a mirror that is disposed on a left side in the X-axis direction of the light receiving lens 32 and that changes a light propagating direction. The light receiving element 31 is disposed on a lower part of the received rotating light mirror 33.The received light rotating mirror 33 is disposed to bend a light path downward by about 90° so that light incident from the received light deviating portion 20 bvia the light receiving lens 32 reaches the light receiving element 31.The light receiving lens 32 is disposed between the received light deviating portion 20 band the received light rotating mirror 33. The light receiving lens 32 concentrates light so that a beam diameter of an optical beam incident on the light receiving element 31 becomes about an element width of the APD.[6. Operation of Optical Detection Module]Transmission light output from the light emitting module 11 is incident on the projection light deviating section 20 a. Further, transmission light output from the light emitting module 12 is incident on the projection light deviating portion 20 aafter a propagation direction at the projection light rotating mirror 15 is bent by about 90°. The transmission light incident on the projection light deviating portion 20 ais emitted in a direction according to a rotation angle of the mirror module 21 via the optical window 200. A radiation range of the transmission light via the mirror module 21 is a scanning range. For example, a range of ± 60° propagating along the X-axis direction may be set as a sensing range on the assumption that a front direction along the Z-axis is 0 degrees. Transmission light emitted within the scanning range is indicated by an optical path B in FIGS. 6 and 7.Reflection light from a subject existing in a predetermined direction according to a rotational position of the mirror module 21, that is, in an emission direction of the transmission light from the projection light deviating portion 20 apass through the optical window 200 and is reflected at the reception light deviating portion 20 b. Then, the reflection light is received at the light receiving element 31 via the light receiving lens 32 and the received light rotating mirror 33.[7. Positions of the shielding portion and the low reflection portion with respect to the return light optical path]In a configuration including the optical window 200 and performing scanning for light using the reflecting mirrors 211 and 212 that are rotationally driven as in the lidar device 1 of the present embodiment, there is a case where a part of the transmission light returns to the projection light deviating portion 20 aas return light RL. In other words, as illustrated in FIGS. 6 and 7, there is a case in which, when transmission light reflected at the projection light deviating portion 20 apass through the optical window 200, a part of the transmission light is further reflected at the optical window 200 to become returning light RL and returns to the projection light deviating portion 20 awithout being emitted to the outside of the housing 100. Note that an original optical path B of the transmission light reflected and emitted at the projection light deviating portion 20 aof the deviating mirror 211 is indicated by a solid line, and an optical path of the returning light RL is indicated by a broken line. In FIG. 7, only returning light RL incident on a side surface on the optical window 200 side of the projection light deviating portion 20 aof the deviating mirror 211 under the generated returning light RL is indicated by a broken line. Further, transmission light reflected at the optical window 200 and becoming the return light RL among the transmission light is indicated by a double line.A case where the returning light RL is incident on the reflection surface of the projection light deflection section 20 aof the deflection mirror 211 is illustrated in FIG. 6. In a case where the low reflection portion 215 is not provided, the returning light RL is again reflected on the reflection surface of the projection light deviating portion 20 aand becomes, as indicated by a broken line, stray light SL emitted in a direction different from a direction in which the light should be originally emitted. When the stray light SL is reflected on an object, the light returns in a reverse direction on a path that is the same as the path on which the light is emitted, and is received at the light receiving portion 30. Thereby, a ghost image occurs which is an object detected although the object does not actually exist. While the transmission light output from the projection section 10 is reflected at a portion around a center of the reflection surface of the projection light deviating section 20 a, the returning light RL is reflected at a portion closer to the optical window 200 than the portion at which the transmission light is reflected.In the present embodiment, the low-reflection portion 215 is formed in a region where the return light RL is reflected on the reflection surface of the projection light deviating portion 20 a, and therefore an amount of the return light RL that is reflected is reduced, so that an amount of the stray light SL is reduced. Note that the low-reflection portion 215 is formed closer to the optical window 200 than a center portion on the reflection surface of the projection light deflection portion 20 awhich is a region in which the transmission light is reflected, and therefore the reflection of the transmission light is less affected.Further, a case where the returning light RL is incident on a side surface on the optical window 200 side of the projection light deviating portion 20 aof the deviating mirror 211 is illustrated in FIG. 7. In a case where the shielding portion 214 ais not provided, the returning light RL enters the inside of the deflecting mirror 211 from the side surface and, as indicated by a broken line, passes along the inside of the deflecting mirror 211 from the projection light deflecting portion 20 ato the reception light deflecting portion 20 bwhile repeatedly reflecting the returning light RL. In a case where the shielding portion 214 bis not provided, the returning light RL, which passes along the inside of the reflecting mirror 211 and reaches the side surface on the light receiving portion 30 side of the receiving light deviating portion 20 b, exits from the side surface of the reflecting mirror 211 and is received at the light receiving portion 30. This results in a ghost image.In the present embodiment, the shielding portion 214 ais formed on the side surface of the projection light deviating portion 20 athat becomes an input when the returning light RL enters the inside of the deviating mirrors 211 and 212. Further, the shielding portion 214 bis formed on the side surface of the received light deviating portion 20 bwhich becomes an output of the returning light RL passing along the inside of the deviating mirrors 211 and 212. This reduces an amount of the returning light RL that passes along the inside of the reflecting mirrors 211 and 212 and is received at the light receiving portion 30.[8. Effects]According to the embodiment described above in detail, the following effects can be obtained.(8a) In the lidar device 1, each of the pair of reflecting mirrors 211 and 212 has the shielding portion 214a, which is a portion through which light is less likely to pass, on a side surface that is closer to the optical window 200 in a state in which the reflection surface faces the projection portion 10, out of both side surfaces that are disposed on the projection light deviating portion 20a via the rotation axis. This can prevent the return light RL incident on the side surface from entering the inside of the reflecting mirrors 211 and 212 from the side surface.Further, in the lidar device 1, each of the pair of reflecting mirrors 211 and 212 has the shielding portion 214 b, through which light is less likely to pass, on a side surface farther from the optical window 200 in a state where the reflection surface faces the light receiving portion 30, of both side surfaces disposed on the received light deviating portion 20 bvia the rotation axis. This can prevent the return light RL entering the inside of the folding mirrors 211 and 212 from passing from the side surface to the outside of the folding mirrors 211 and 212 and being received at the light receiving section 30.According to such a configuration, an amount of the return light RL that passes along the inside of the reflecting mirrors 211 and 212 and is received at the light receiving portion 30 is reduced, so that an occurrence of a ghost due to the return light RL can be reduced.(8b) In the lidar device 1, each of the pair of reflecting mirrors 211 and 212 includes the low reflection portion 215, which is a portion that is less likely to reflect light, at an end portion of the reflection surface of the projection light deviating portion 20 athat becomes the optical window 200 side in a state where the reflection surface faces the projection portion 10. According to such a configuration, it is possible to prevent the return light RL from being reflected on the reflection surface of the projection light deviating portion 20 a, so that an amount of the stray light SL generated by the reflection is reduced, so that it is possible to further reduce an occurrence of a ghost due to the return light RL.Note that the transmission light output from the projection section 10 is reflected at a portion around the center of the reflection surface of the projection light deflection section 20 a, and the returning light RL is reflected at a portion closer to the optical window 200 than the portion at which the transmission light is reflected. The low reflection portion 215 is formed at a portion closer to the optical window 200 than the center portion of the reflection surface of the projection light deflection portion 20 a, which is a region where the transmission light is reflected, and therefore reflection of the transmission light is less affected while the reflection of the returning light RL is prevented.(8c) In the lidar device 1, the shielding portions 214a and 214b and the low-reflection portion 215 are formed by the same black ink printed on surfaces of the reflecting mirrors 211 and 212, and the shielding portion 214a and the low-reflection portion 215 are continuously formed. According to such a configuration, it is possible to easily and efficiently manufacture the shield portions 214 aand 214 band the low reflection portion 215.Note that, in the present embodiment, the transmission light corresponds to a transmission wave, the projection section 10 corresponds to a transmission section, the reflection light corresponds to a reflection wave, the light receiving section 30 corresponds to a receiving section, the projection light deviating section 20 acorresponds to a transmission deviating section, the received light deviating section 20 bcorresponds to a receiving deviating section, the optical window 200 corresponds to a transmissive window, and black ink corresponds to a black coating.[9. Other Embodiments]While the embodiment of the present invention has been described above, it is to be understood that the present invention is not limited to the above-described embodiment and may take various forms.(9a) In the above-described embodiment, both the shield portion 214a and the shield portion 214b are formed on each of the reflecting mirrors 211 and 212. However, only one of the shield portion 214 aand the shield portion 214 bmay be formed.(9b) In the above-described embodiment, at each of the reflecting mirrors 211 and 212, the shielding portion 214a is formed on a side surface that is closer to the optical window 200 in a state where the reflection surface faces the projection portion 10, from both side surfaces that are disposed at the projection light deviating portion 20a via the rotation axis. However, a position where the shield portion 214 ais formed is not limited to this position. For example, the shielding portion 214 amay be formed on both side surfaces via the rotation axis at the projection light deviating portion 20 aor may be formed on all side surfaces of the projection light deviating portion 20 a.(9c) In the above-described embodiment, at each of the reflecting mirrors 211 and 212, the shielding portion 214b is formed on a side surface farther from the optical window 200 in a state where the reflecting surface faces the light receiving portion 30, from both side surfaces disposed at the received light deviating portion 20b via the rotation axis. However, a position where the shield portion 214 bis formed is not limited to this position. For example, the shielding portion 214 bmay be formed on both side surfaces via the rotation axis at the received light deviating portion 20 b, or may be formed on all side surfaces of the received light deviating portion 20 b.(9d) In the above-described embodiment, while the shield portions 214a and 214b and the low-reflection portion 215 are formed by printed black ink, a method of forming the shield portions 214a and 214b and the low-reflection portion 215 is not limited thereto. Substances of the shielding portions 214 aand 214 band the low-reflection portion 215 may be different from each other when the shielding portions 214 aand 214 bare formed with a substance through which light is less likely to pass and the low-reflection portion 215 is formed with a substance that reflects light with less likelyness.(9e) In the above-described embodiment, while the lidar device 1 has been described as an example of a distance measurement device, a type of the distance measurement device is not limited thereto. For example, the distance measurement device may be a millimeter wave radar device or the like.(9f) Functions of a component in the above-described embodiment may be distributed as a plurality of components, or functions of a plurality of components may be integrated into one component. Further, a part of the configuration of the above-described embodiment may be omitted. Moreover, at least a part of the configuration of the above-described embodiment may be added to or replaced with configurations of other embodiments.

Claims

A distance measurement apparatus (1) comprising: a transmission section (10) configured to output a transmission wave; a reception section (30) configured to detect a reflection wave from an object irradiated with the transmission wave; a mirror module (21) including a pair of deflection mirrors (211, 212) that deflect the transmission wave and the reflection wave in a direction according to a rotation angle of a reflection surface, and a mirror support (213) that supports the pair of deflection mirrors by being interposed between the pair of deflection mirrors and configured to rotate according to driving of a motor (24); Partition plates (22, 23) which are plate-like members provided to divide the pair of reflecting mirrors into two portions, transmission reflecting portion (20a) which is a portion located on the transmission portion side and reception reflecting portion (20b) which is a portion located on the reception portion side and which are configured to integrally rotate with the mirror module; a housing (100) which is configured to house the transmission portion, the reception portion, the mirror module and the partition plates; and a transmissive window (200) provided at an opening of the housing and allowing the transmission wave and the reflection wave to pass therethrough, wherein each of the pair of deflection mirrors includes shielding portions (214 a, 214 b) through which transmission waves are suppressed from passing, on at least one of the side surfaces, a side surface closer to the transmissive window in a state in which the reflection surface faces the transmission portion, from both side surfaces disposed on the transmission deflection portion via a rotation axis, or a side surface farther from the transmissive window in a state in which the reflection surface faces the reception portion, from both side surfaces disposed on the reception deflection portion via the rotation axis.The distance measurement apparatus according to claim 1, wherein each of the pair of reflecting mirrors further comprises a low reflection portion (215) that suppresses the reflection of the transmission waves at an end portion of the reflection surface of the transmission reflecting portion that is on the transmissive window side in a state where the reflection surface faces the transmission portion.The distance measurement device according to claim 2, wherein the shielding portions and the low-reflection portion are black coatings.

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