Light projection device, light projection / reception device, and distance measuring device

Abstract

To provide a light projection device capable of projecting light with reduced intensity irregularities.SOLUTION: The light projection device has a light source that emits light with a cross-sectional shape having longitudinal and transverse directions and a light shielding part that shields a longitudinal end of the light.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a light-projecting device that projects light, a light-projecting and light-receiving device that projects and receives light, and a distance measuring device that performs optical distance measurement. [Background technology]

[0002] Distance measuring devices that measure the distance to an object by irradiating the object with light and detecting the light reflected by the object have been known. Also, scanning type distance measuring devices that measure the distance to a plurality of objects by performing optical scanning have been known. For example, Patent Document 1 discloses an optical radar device including a light projecting unit, a light receiving unit, and a distance measuring means. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-85832 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, a distance measuring device is provided with a light projecting unit that projects a laser light for distance measurement, and a light receiving unit that receives the light reflected by an object. In addition, as a configuration of the light projecting unit and the light receiving unit, for example, a configuration in which the light projecting unit projects a laser light having a predetermined elongated beam shape, and the light receiving unit receives the reflected light from the object by a plurality of light receiving elements can be mentioned. In this case, light can be projected and received simultaneously on a plurality of target areas (such as a plurality of objects or a plurality of surface areas of the object).

[0005] Here, in consideration of performing accurate distance measurement for each of the multiple target regions, it is preferable, for example, to project light of uniform intensity onto each of the multiple target regions, i.e., it is preferable that there is little unevenness in intensity within the projected light beam.

[0006] The present invention has been made in consideration of the above-mentioned points, and has as its object to provide a light projecting device capable of projecting light with reduced unevenness in intensity. Another object of the present invention is to provide a light projecting and receiving device capable of accurate light projection and reception by projecting light with reduced unevenness in intensity, and a distance measuring device capable of accurate distance measurement. [Means for solving the problem]

[0007] The invention described in claim 1 is characterized by having a light source that emits light having a cross-sectional shape having a longitudinal direction and a lateral direction, and a light-shielding portion that blocks the longitudinal end portion of the light. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an overall configuration of a distance measuring device according to a first embodiment. [Diagram 2] 2 is a diagram showing a light exit surface of a light source in the distance measuring device according to the first embodiment. FIG. [Diagram 3] 3 is a diagram illustrating a configuration example of a light blocking unit in the distance measuring device according to the first embodiment. FIG. [Figure 4] 2 is a diagram showing a light receiving surface of a light receiving element in the distance measuring device according to the first embodiment. [Diagram 5] 2 is a diagram illustrating an example of the configuration of a light receiving optical system in the distance measuring device according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described in detail below with reference to the embodiments. EXAMPLES

[0010] Fig. 1 is a schematic layout diagram of a distance measuring device 10 according to the first embodiment. The distance measuring device 10 is a scanning type distance measuring device that performs optical scanning of a predetermined area (hereinafter referred to as a scanning area) R0 and measures the distance to an object OB present within the scanning area R0. The distance measuring device 10 will be described with reference to Fig. 1. Note that Fig. 1 shows a schematic diagram of the scanning area R0 and the object OB.

[0011] First, the distance measuring device 10 has a light source 11 that generates and emits pulsed light (hereinafter referred to as primary light) L1. In this embodiment, the light source 11 generates laser light having a peak wavelength in the infrared region as the primary light L1 and emits it intermittently. In this embodiment, the light source 11 also emits laser light having a line-shaped cross-sectional shape as the primary light L1.

[0012] The distance measuring device 10 has an imaging optical system 12 that forms an image (intermediate image) of the primary light L1, that is, an image showing the cross-sectional shape (beam shape) of the primary light L1. The imaging optical system 12 includes, for example, a relay lens.

[0013] The distance measuring device 10 has a light shielding section 13 that shields a part of the primary light L1. In this embodiment, the light shielding section 13 is disposed at a position (image forming point) where an image of the primary light L1 is formed. The primary light L1 that has passed through the light shielding section 13 is output from the light shielding section 13 as secondary light L2.

[0014] In this embodiment, the light blocking section 13 is a light blocking plate having an opening. In this embodiment, a part of the primary light L1 is blocked by the light blocking section 13. The primary light L1 that is not blocked by the light blocking section 13 passes through the opening of the light blocking section 13 as secondary light (hereinafter, may be referred to as projected light) L2. In this embodiment, the light blocking section 13 is a reflecting plate that is reflective to the primary light L1.

[0015] The distance measuring device 10 has a light receiving element (first light receiving element) 14 that receives reflected primary light L1R, which is a portion of the primary light L1 reflected by the light blocking portion 13. For example, the light receiving element 14 includes at least one detection element that detects the reflected primary light L1R.

[0016] The distance measuring device 10 has a light projecting optical system 15 that projects the secondary light L2, that is, the primary light L1 that has passed through the light blocking portion 13. The light projecting optical system 15 includes, for example, at least one lens.

[0017] The distance measuring device 10 has a deflection element (first deflection element) 16 that deflects the secondary light L2 in a variable direction and projects it as tertiary light (hereinafter, sometimes referred to as scanning light) L3. The deflection element 16 operates periodically to periodically change the deflection direction of the secondary light L2. The deflection element 16 outputs the secondary light L2 while bending the traveling direction of the secondary light L2, and also periodically changes the bending direction. The secondary light L2 deflected by the deflection element 16 is projected as tertiary light L3 toward the scanning region R0.

[0018] In this embodiment, the deflection element 16 has at least one rotating mirror 16A that rotates around a rotation axis AY and reflects the secondary light L2. For example, the deflection element 16 includes a polygon mirror. In this embodiment, the deflection element 16 periodically changes the reflection direction of the secondary light L2 by reflecting the secondary light L2 while the rotating mirror 16A rotates. That is, in this embodiment, the tertiary light L3 is the secondary light L2 reflected by the rotating mirror 16A of the deflection element 16.

[0019] The scanning region R0 is a virtual three-dimensional space onto which the tertiary light L3, which is the secondary light L2 that has passed through the deflection element 16, is projected. In Fig. 1, the outer edge of the scanning region R0 is diagrammatically indicated by a dashed line.

[0020] In this embodiment, the light source 11 emits, as the primary light L1, a laser beam having a linear cross-sectional shape extending along the axial direction of the rotation axis AY of the rotating mirror 16A.

[0021] Therefore, for example, the scanning region R0 can be defined as a cone-shaped space having a height direction range along the longitudinal direction (hereinafter referred to as the first direction) D1 in the cross section of the secondary light L2, a width direction range along a direction (hereinafter referred to as the second direction) D2 corresponding to the variable range of the deflection direction of the secondary light L2 by the deflection element 16, and a distance direction range (i.e., depth range) in which the tertiary light L3 can maintain a predetermined intensity.

[0022] In addition, when a virtual plane located a predetermined distance away from the deflection element 16 in the scanning region R0 is defined as a scanning surface R1, the scanning surface R1 can be defined as a two-dimensional region spreading along a first direction D1 and a second direction D2. The tertiary light L3 is projected toward the scanning region R0 so as to scan the scanning surface R1. In this embodiment, the first direction D1 corresponds to the main scanning direction, and the second direction D2 corresponds to the sub-scanning direction.

[0023] 1, when an object OB (i.e., an object or material having reflectivity or scattering properties for the secondary light L2) is present in the scanning region R0, the tertiary light L3 is reflected or scattered by the object OB. A part of the tertiary light L3 reflected by the object OB travels as fourth-order light (hereinafter, may be referred to as reflected light) L4 along substantially the same optical path as the tertiary light L3 in the opposite direction to the tertiary light L3, and returns to the deflection element 16.

[0024] The distance measuring device 10 has a deflection element (second deflection element) 17 that is provided on the optical path of the fourth-order light L4, in this embodiment, on an optical path common to the second-order light L2 and the fourth-order light L4 between the deflection element 16 and the projection optical system 15 (light blocking section 13) and deflects the fourth-order light L4. For example, the deflection element 17 is a light separation element that separates the second-order light L2 and the fourth-order light L4 by transmitting the second-order light L2 and reflecting the fourth-order light L4, and is a beam splitter in this embodiment.

[0025] In other words, in this embodiment, the deflection element 16 is a movable deflection element for scanning that variably deflects the secondary light L2 in a direction by operating, whereas the deflection element 17 is a fixed type deflection element.

[0026] The distance measuring device 10 has a light receiving optical system 18 that receives the fourth-order light L4 deflected by the deflection element 17. The light receiving optical system 18 collects and shapes the fourth-order light L4. The light receiving optical system 18 includes, for example, at least one lens.

[0027] The distance measuring device 10 also has a light receiving element (second light receiving element) 19 that receives the fourth-order light L4. The light receiving element 19 is disposed, for example, at the focal position of the fourth-order light L4 collected by the light receiving optical system 18. For example, the light receiving element 19 has at least one detection element that detects the fourth-order light L4 and generates an electrical signal according to the fourth-order light.

[0028] The light receiving element 19 generates the electrical signal as a detection result (light receiving result) of the fourth-order light L4. That is, the distance measuring device 10 generates the electrical signal generated by the light receiving element 19 as a scanning result of the scanning region R0.

[0029] The distance measuring device 10 has a control unit 20 that drives and controls the light source 11, the light receiving element 14, the deflection element 16, and the light receiving element 19. For example, in this embodiment, the control unit 20 includes a light source control unit 21 that drives and controls the light source 11, and a monitoring unit 22 that receives a part of the primary light L1 and monitors the primary light L1. The control unit 20 also drives the light receiving element 14, the deflection element 16, and the light receiving element 19.

[0030] The control unit also has a distance measuring unit 23 that measures the distance to the object OB based on the result of receiving the fourth light L4 by the light receiving element 19. In this embodiment, the distance measuring unit 23 detects a pulse indicating the fourth light L4 from the electrical signal. The distance measuring unit 23 also measures the distance to the object OB (or a part of its surface area) by a time-of-flight method based on the time difference between the projection timing of the third light L3 and the reception timing of the fourth light L4. The distance measuring unit 23 also generates data (distance measurement data) indicating the measured distance information.

[0031] In this embodiment, the distance measuring unit 23 divides the scanning area R0 (scanning surface R1) into a plurality of distance measuring points (scanning points) and generates an image (distance measuring image) of the scanning area R0 that indicates the distance measuring results (distance values) of each of the plurality of distance measuring points as pixels. In this embodiment, the distance measuring unit 23 associates the distance measuring points with information indicating the displacement of the rotating mirror 16A and generates image data that indicates a two-dimensional map or a three-dimensional map of the scanning area R0.

[0032] The distance measuring unit 23 sets the period of change in the projection direction of the tertiary light L3, that is, the period of scanning the scanning region R0, as the period of generating distance measuring images, and generates one distance measuring image for each scanning period.

[0033] The scanning period refers to a period from a predetermined displacement of the rotating mirror 16A to a return to the predetermined displacement again when the distance measuring device 10 periodically performs optical scanning on the scanning area R0. The distance measuring unit 23 may also have a display unit (not shown) that displays the generated distance measuring images as a video in chronological order.

[0034] 2 is a diagram illustrating a schematic view of a light emission surface 11A of the light source 11. In this embodiment, the light source 11 has three laser bars E1, E2, and E3 each extending in a first direction D1, and has a structure in which these laser bars E1 to E3 are stacked along a second direction D2 (i.e., the short side direction of each of the laser bars E1 to E3).

[0035] Each of the laser bars E1 to E3 emits a linear or elliptical laser beam having a cross-sectional shape (beam shape) with the first direction D1 as the longitudinal direction and the second direction D2 as the lateral direction. Each of the laser bars E1 to E3 is aligned along the second direction D2 and emits a laser beam along optical axes extending parallel to each other.

[0036] The light source 11 emits the entire laser light emitted from these laser bars E1 to E3 as primary light L1. In this embodiment, the primary light L1 as a whole has a line-like cross-sectional shape having a first direction D1 and a second direction D2 as a longitudinal direction and a transverse direction, respectively.

[0037] 3 is a diagram showing a schematic configuration of the light shielding portion 13 and a cross-sectional shape of the secondary light L2 generated by the light shielding portion 13. As shown in FIG. 3, in this embodiment, the primary light L1 emitted from the light source 11 includes a plurality of primary laser beams L11, L12, and L13 each having a cross-sectional shape with a first direction D1 and a second direction D2 as a longitudinal direction and a transverse direction, respectively. For example, the primary laser beams L11, L12, and L13 correspond to the laser beams emitted from the laser bars E1, E2, and E3, respectively.

[0038] That is, in this embodiment, the light source 11 emits, as primary laser beams L11, L12 and L13, a plurality of beams each having a cross-sectional shape with a longitudinal direction and a lateral direction and arranged along the lateral direction.

[0039] In this embodiment, the light blocking portion 13 is disposed at a position where an image (intermediate image) L1P of the light exit surface 11A of the primary light L1 in the light source 11 is formed by the imaging optical system 12. Fig. 3 shows each of the images of the light exit surfaces of the primary laser beams L11 to L13 constituting the image L1P.

[0040] Moreover, the primary laser beams L11, L12, and L13 that have passed through the light-shielding portion 13 pass through the light-shielding portion 13 as secondary laser beams L21, L22, and L23, respectively. The secondary light L2 includes these three secondary laser beams L21, L22, and L23. Moreover, the secondary light L2 as a whole has a line-like cross-sectional shape having the first direction D1 and the second direction D2 as the longitudinal direction and the transverse direction, respectively.

[0041] 3, in this embodiment, the light shielding portion 13 is constructed and arranged to shield each end of the primary laser beams L11 to L13. In this embodiment, the light shielding portion 13 shields each end of the primary laser beams L11 to L13 so that the lengths of the secondary laser beams L21 to L23, i.e., the primary laser beams L11 to L13 that have passed through the light shielding portion 13, along the first direction D1 are uniform.

[0042] Therefore, each of the secondary laser beams L21 to L23 has a cross-sectional shape with the same longitudinal length and the same longitudinal end position. Therefore, the secondary light L2 is projected as light having a rectangular outer shape with a clear outer edge in the longitudinal direction.

[0043] Here, the primary light L1 and the secondary light L2 will be described. For example, when trying to increase the measurable distance of the distance measuring device 10, it is conceivable to increase the intensity of the light projected as the tertiary light L3. Then, in consideration of emitting high-intensity primary light L1, it is conceivable to use a high-output light source as the light source 11.

[0044] In addition, in consideration of obtaining the fourth-order light L4 from a plurality of regions in the scanning region R0 collectively, it is conceivable to use a laser element in which the above-mentioned laser bars E1 to E3 are stacked as the light source 11. This makes it possible to obtain high-output line-shaped third-order light L3 while suppressing, for example, an increase in size or complexity of the optical system.

[0045] On the other hand, in the case of a stacked laser element as the light source 11, the shapes of the light emitting surfaces of the laser bars E1 to E3 are slightly different. Specifically, for example, as shown in Fig. 2, the lengths in the longitudinal direction (bar lengths) of the laser bars E1 to E3 are slightly different. For example, the bar length of the laser bar E1 is the longest, and the bar length of the laser bar E3 is the longest.

[0046] In this case, of the primary laser beams L11 to L13, the primary laser beam L11 has the shortest beam shape, and the primary laser beam L13 has the longest beam shape, as shown in Fig. 3. The primary light L1 consisting of the primary laser beams L11 to L13 has different intensities as a whole between the center and the ends in the first direction D1.

[0047] Therefore, for example, the light corresponding to the center of the first direction D1 of the primary light L1 may have sufficient intensity, while the light corresponding to the end of the first direction D1 of the primary light L1 may not have sufficient intensity. Therefore, if the primary light L1 is directly projected as the tertiary light L3, there may be areas in the scanning area R0 where a sufficient amount of the tertiary light L3 is irradiated and areas where a sufficient amount of the tertiary light L3 is not irradiated. Therefore, there may be cases where the distance measurement accuracy in the scanning area R0 is uneven, or there may be areas where the measurable distance is shorter than other areas.

[0048] In contrast, in this embodiment, a light shielding portion 13 is arranged to shield the ends of the primary laser beams L11 to L13 in the first direction D1. Therefore, the lengths of the secondary laser beams L21 to L23 in the first direction D1 are uniform, and the intensity of the secondary light L2 as a whole along the first direction D1 is uniformed. Therefore, the amount of the tertiary light L3 projected onto the scanning region R0 is uniformed, and scanning and distance measurement can be performed with stable accuracy over the entire scanning region R0.

[0049] In this embodiment, only a part of the primary light L1 is projected as the secondary light L2. That is, the secondary light L2 has a smaller intensity than the primary light L1. In response to this, the light source control unit 21 of the control unit 20 controls the intensity of the primary light L1, i.e., the output of the light source 11, so that the secondary light L2 has a designed light amount. That is, the light source 11 emits the primary light L1 with an output based on the light amount of the secondary light L2, which is the primary light L1 that has passed through the light blocking unit 13.

[0050] More specifically, for example, the light source 11 emits a laser beam as the primary light L1. The distance measuring device 10 is assumed to be mounted on a moving object such as a vehicle and to measure distances in various spaces as the scanning region R0. In this case, it is assumed that the laser beam is irradiated onto a human being. Therefore, it is necessary to consider the upper limit intensity of the laser beam that can be projected as the tertiary light L3.

[0051] In this embodiment, the light source control unit 21 controls the output of the light source 11 for setting the light amount of the tertiary light L3 based on the light amount of the secondary light L2. In other words, the output control of the light source 11 is performed in consideration of the secondary light L2 having a light amount closer to the light amount of the tertiary light L3 than the primary light L1. Therefore, the tertiary light L3 can be projected while performing appropriate output adjustment while satisfying the output limit of the laser light.

[0052] In this embodiment, the light-shielding portion 13 is reflective to the primary light L1. A light-receiving element 14 is provided to receive the reflected primary light L1R reflected by the light-shielding portion 13. The monitoring unit 22 monitors the primary light L1 based on the result of reception of the reflected primary light L1R by the light-receiving element 14.

[0053] That is, when the light blocking portion 13 reflects a part of the primary light L1, the reflected primary light L1 can be used to monitor the light source 11. Therefore, the operation of the light source 11 can be monitored simply by providing the light receiving element 14. In other words, when the light blocking portion 13 is reflective to the primary light L1, the distance measuring device 10 can have a monitoring function with a simple configuration by providing a monitoring portion 22 that receives the primary light L1 reflected by the light blocking portion 13 and monitors the primary light L1 (e.g., the amount of primary light L1).

[0054] Fig. 4 is a diagram showing a schematic view of a light receiving surface 19R of the light receiving element 19. As shown in Fig. 4, the light receiving element 19 has a light receiving surface 19R made up of a plurality of light receiving segments 19A arranged along a first direction D1. In this embodiment, the light receiving element 19 is a line sensor in which the light receiving segments 19A are arranged in a row and have a linear light receiving surface 19R.

[0055] In this embodiment, each of the light receiving segments 19A receives the fourth-order light L4 independently of each other. Each of the light receiving segments 19A has at least one photoelectric conversion element.

[0056] 5 is a diagram showing an example of the configuration of the light receiving optical system 18 and the light receiving element 19. In this embodiment, the light receiving optical system 18 collects the fourth-order light L4 so that the fourth-order light L4 is incident on the entire light receiving surface 19R of the light receiving element 19 in the first direction D1. Therefore, the fourth-order light L4 is incident on each of the light receiving segments 19A. Then, an electrical signal corresponding to the portion of the fourth-order light L4 received by each light receiving segment 19A is generated by each of the light receiving segments 19A.

[0057] In other words, the light receiving optical system 18 is adjusted to have a light collecting characteristic that maximizes the operation of the light receiving element 19 in accordance with the beam shape (in this embodiment, the length of the beam in the first direction D1) of the primary light L1 that has passed through the light shielding portion 13. Therefore, accurate light receiving operation can be performed in all of the light receiving segments 19A.

[0058] Thus, in this embodiment, the distance measuring device 10 has a light source 11 that emits primary light L1 having a cross-sectional shape with the first direction D1 as its longitudinal direction, and a light shielding portion 13 that shields the end portion of the primary light L1 in the first direction D1. Therefore, projection of the light at the end portion of the primary light L1, i.e., the light with low intensity in the primary light L1, is blocked. Therefore, it becomes possible to project secondary light L2 with reduced intensity unevenness, and accurate scanning and distance measurement can be performed.

[0059] In this embodiment, the light source 11 includes a stacked laser element in which a plurality of laser bars E1 to E3 are stacked, but the configuration of the light source 11 is not limited to this.

[0060] For example, the light source 11 may be configured to emit a plurality of beams (e.g., primary laser beams L11 to L13) each having a cross-sectional shape with a longitudinal direction (e.g., a first direction D1) and a lateral direction (e.g., a second direction D2). For example, the light source 11 may include various light-emitting elements and have an optical system that shapes the light emitted from the light-emitting elements as described above.

[0061] Furthermore, the light source 11 is not limited to being configured to emit a plurality of primary laser beams L11 to L13. For example, the light source 11 may be configured to emit only one primary laser beam (for example, only the primary laser beam L12) as the primary light L1.

[0062] Specifically, when projecting primary light L1 having a line-shaped cross-sectional shape like the primary light L1, the ends of the primary light L1 may have a smaller intensity than the center. Also, the intensity of the ends of the primary light L1 may not be as stable as the intensity of the center. In this way, the characteristics of the ends of the primary light L1 may be more unstable than the characteristics of the center of the primary light L1. Therefore, it is preferable to project only the center of the primary light L1. Therefore, by blocking the ends of the primary light L1 in the first direction D1 emitted from the light source 11, it is possible to project secondary light L2 with a stable intensity.

[0063] In the present embodiment, the light shielding portion 13 is configured to shield each of the ends of the primary laser beams L11 to L13. However, the configuration of the light shielding portion 13 is not limited to this. The light shielding portion 13 may be configured to shield at least one end of the primary laser beams L11 to L13.

[0064] In addition, when the light source 11 emits primary light L1 consisting of multiple lights (e.g., primary laser lights L11 to L13), as described above, it is preferable that the light-shielding portion 13 is configured to block the end portion in the first direction D1 of at least one of the multiple lights so that the length in the first direction D1 of the light that has passed through the light-shielding portion 13 (that is not blocked by the light-shielding portion 13) is uniform.

[0065] Moreover, the light shielding portion 13 is not limited to being configured to align the length in the first direction D1 of the light that has passed through the light shielding portion 13. The light shielding portion 13 may be configured to shield an end portion in the first direction D1 of at least one light (for example, only the primary laser light L13, or only the primary laser light L12 and L13) that protrudes more than the other lights in the first direction D1 among the multiple lights emitted from the light source 11. Even in this case, it is expected that the intensity unevenness of the primary light L1 will be reduced.

[0066] In the present embodiment, the light blocking portion 13 is reflective to the primary light L1. However, the light blocking portion 13 only needs to be configured to block (not transmit) the end portion of the primary light L1 in the first direction D1. For example, the light blocking portion 13 may be absorptive to the primary light L1.

[0067] If the light-shielding portion 13 does not have reflectivity for the primary light L1, the light-receiving element 14 does not need to be provided. In this case, the light source 11 may be monitored by other general means without using the light-shielding portion 13.

[0068] In addition, in this embodiment, the case where the light blocking portion 13 is made of a light blocking plate having an opening on the optical path of a part of the primary light L1 (the central part in this embodiment) has been described. However, the configuration of the light blocking portion 13 is not limited to this. For example, the light blocking portion 13 may have a transmitting portion that transmits the primary light L1 on the optical path of the central part of the primary light L1, and the other part may be a transparent plate having light blocking properties. Furthermore, the light blocking portion 13 may have multiple light blocking plates.

[0069] Furthermore, the light shielding portion 13 may be configured to shield only one of the ends of the primary light L1 in the first direction D1. For example, depending on the relationship of the beam shapes among the primary laser lights L11 to L13, the primary laser light L13 may protrude most at one end in the first direction D1, and the primary laser light L12 may protrude most at the other end. In this case, the light shielding portion 13 may be configured to shield the end of the primary laser light L13 at the one end, and to shield the end of the primary laser light L12 at the other end.

[0070] In this embodiment, the imaging optical system 12 that forms an image L1P of the primary light L1 is provided, and the light blocking portion 13 is disposed at a position where the image L1P of the primary light L1 is formed. However, the position of the light blocking portion 13 is not limited to this.

[0071] For example, the distance measuring device 10 may not have the imaging optical system 12. Furthermore, the light blocking portion 13 may be disposed very close to the light emission surface 11A of the light source 11. That is, the primary light L1 may be configured such that a part of the primary light L1 is blocked by the light blocking portion 13 immediately after being emitted from the light source 11.

[0072] In addition, in order to reliably block the end of the primary light L1, it is preferable to dispose the light-shielding portion 13 at the imaging position of the image L1P of the light emission surface 11A of the light source 11 after disposing the imaging optical system 12. Specifically, if the light-shielding portion 13 is disposed at a position other than the imaging position of the image L1P, the end of the primary light L1 that has passed through the light-shielding portion 13 may not be reliably blocked.

[0073] In other words, the distance measuring device 10 preferably has an imaging optical system 12 that is provided on the optical path of the primary light L1 between the light source 11 and the light blocking unit 13 and that forms an image L1P of the light emission surface 11A of the light source 11. In addition, the light blocking unit 13 is preferably disposed at a position where this image L1P is formed.

[0074] In this embodiment, the case has been described where the light source control unit 21 of the control unit 20 controls the light source 11 to emit the primary light L1 with an intensity corresponding to the light amount of the secondary light L2. However, the light source 11 may be configured to emit the primary light L1 in a predetermined manner or to adjust the emission manner of the primary light L1, for example.

[0075] Thus, in this embodiment, the distance measuring device 10 has a light source 11 that emits light (primary light L1) having a cross-sectional shape having a longitudinal direction (first direction D1) and a transverse direction (second direction D2), a shading section 13 that shades the longitudinal end of the light, and a deflection element 16 that deflects the light (secondary light L2) that has passed through the shading section 13 in a variably directional manner and projects it toward an object OB in the scanning area R0.

[0076] The distance measuring device 10 also includes a light receiving element 19 that receives reflected light (quaternary light L4), which is light (tertiary light L3) reflected by the object OB, and has a light receiving surface 19S made up of a plurality of light receiving segments 19A arranged along a direction corresponding to the longitudinal direction, and a distance measuring unit 23 that measures the distance to the object OB based on the result of receiving the reflected light by the light receiving element 19. Therefore, it is possible to provide a distance measuring device 10 that can perform accurate distance measurement by projecting light with reduced intensity unevenness.

[0077] The result of receiving the fourth-order light L4 by the light receiving element 19 can be effectively used for purposes other than distance measurement, such as for detecting an object OB. Therefore, the distance measuring device 10 does not need to have the distance measuring unit 23. In this case, for example, the light source 11, the light blocking unit 13, the deflection element 16, and the light receiving element 19 in the distance measuring device 10 function as a scanning device, that is, a scanning type light projecting and receiving device.

[0078] Furthermore, the distance measuring device 10 does not have to have the deflection element 16 in addition to the distance measuring unit 23. In this case, for example, the light source 11, the light blocking unit 13, and the light receiving element 19 in the distance measuring device 10 function as a non-scanning type light projecting and receiving device. Even in this case, light can be projected and received using light of uniform intensity, for example. In other words, the present invention can also be embodied as a light projecting and receiving device that can perform accurate light projection and reception by projecting light with reduced intensity unevenness.

[0079] Furthermore, the distance measuring device 10 does not need to have the light receiving element 19. In this case, the light source 11 and the light blocking unit 13 function as a light projecting device. In this case, for example, light of uniform intensity can be projected. That is, the present invention can also be implemented as a light projecting device capable of projecting light with reduced intensity unevenness.

[0080] As described above, for example, the light projecting device in this embodiment has the light source 11 that emits light (primary light L1) having a cross-sectional shape having a longitudinal direction (first direction D1) and a lateral direction (second direction D2), and the light shielding portion 13 that shields the end of the light in the longitudinal direction. Therefore, it is possible to project light with reduced intensity unevenness. [Explanation of symbols]

[0081] 10 Ranging device 11 Light source 13 Light shielding section

Claims

[Claim 1] A light source that emits light having a cross-sectional shape that has a longitudinal direction and a lateral direction in a cross section perpendicular to the traveling direction; a light blocking portion that blocks an end portion of the light in the longitudinal direction.

Images