Lighting device, light transmitting and receiving device, and distance measuring device

Abstract

To provide a light projection device capable of projecting light with reduced intensity unevenness. [Solution] The light projection device comprises a light source that emits light with a cross-sectional shape having a longitudinal direction and a transverse direction, and a light-shielding part that shields the end of the light in the longitudinal direction.

Description

Technical Field

[0001] The present invention relates to a light projecting device that projects light, a light projecting and receiving device that performs light projection and reception, and a distance measuring device that performs optical distance measurement.

Background Art

[0002] Conventionally, a distance measuring device that measures the distance to an object by irradiating the object with light and detecting the light reflected by the object is known. Also, a scanning type distance measuring device that performs distance measurement on a plurality of objects by performing light scanning is known. For example, Patent Document 1 discloses an optical radar device including a light projecting unit, a light receiving unit, and distance measuring means.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, a distance measuring device is provided with a light projecting unit that projects laser light for distance measurement and a light receiving unit that receives the light reflected by an object. Further, as a configuration of the light projecting unit and the light receiving unit, for example, a configuration in which the light projecting unit projects 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, it is possible to perform light projection and reception collectively on a plurality of target regions (a plurality of objects or a plurality of surface regions on the object, etc.).

[0005] Here, considering accurately performing distance measurement on each of the plurality of target regions, for example, it is preferable that light having a uniform intensity is projected onto each of the plurality of target regions. That is, it is preferable that there is little intensity unevenness within the beam of the projected light.

[0006] The present invention has been made in view of the above-mentioned points, and one of its objectives is to provide a light projection device capable of projecting light with reduced intensity unevenness. Another objective of the present invention is to provide a light projection and receiving device capable of accurate light projection and reception by projecting light with reduced intensity unevenness, 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 comprising a light source that emits light with a cross-sectional shape having a longitudinal direction and a transverse direction, and a light-shielding portion that shields the end of the light in the longitudinal direction. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the overall configuration of the distance measuring device according to Example 1. [Figure 2] This figure shows the light emission surface of the light source in the distance measuring device according to Example 1. [Figure 3] This figure shows an example of the configuration of the light-shielding section in the distance measuring device according to Example 1. [Figure 4] This figure shows the light-receiving surface of the light-receiving element in the distance measuring device according to Example 1. [Figure 5] This figure shows an example of the configuration of the light-receiving optical system in the distance measuring device according to Example 1. [Modes for carrying out the invention]

[0009] Examples of the present invention will be described in detail below. [Examples]

[0010] Figure 1 is a schematic arrangement diagram of the distance measuring device 10 according to Embodiment 1. The distance measuring device 10 is a scanning type distance measuring device that performs optical scanning of a predetermined area (hereinafter referred to as the scanning area) R0 and measures the distance to an object OB located within the scanning area R0. The distance measuring device 10 will be explained using Figure 1. Figure 1 schematically shows 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 primary light L1 and emits it intermittently. In this embodiment, laser light having a line-shaped cross-section is emitted as 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 of the primary light L1 (an image showing the beam shape). The imaging optical system 12 includes, for example, a relay lens.

[0013] The distance measuring device 10 has a light-shielding section 13 that blocks a portion of the primary light L1. In this embodiment, the light-shielding section 13 is positioned at the location where an image of the primary light L1 is formed (imaging point). 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-shielding portion 13 is a light-shielding plate having an opening. In this embodiment, a portion of the primary light L1 is shielded by the light-shielding portion 13. The primary light L1 that is not shielded by the light-shielding portion 13 passes through the opening of the light-shielding portion 13 as secondary light (hereinafter sometimes referred to as projected light) L2. In this embodiment, the light-shielding portion 13 is a reflector 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-shielding section 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 projection optical system 15 that projects secondary light L2, i.e., primary light L1 that has passed through the light shielding section 13. The light projection 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 second-order light L2 in a direction-variable manner and projects it as third-order light (hereinafter sometimes referred to as scanning light) L3. The deflection element 16 performs a periodic operation to periodically change the deflection direction of the second-order light L2. The deflection element 16 emits the second-order light L2 while bending its traveling direction and periodically changes the bending direction. The second-order light L2 deflected by the deflection element 16 is projected as third-order light L3 toward the scanning region R0.

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

[0019] The scanning region R0 is a virtual three-dimensional space where the third-order light L3, which is the second-order light L2 passing through the deflection element 16, is projected. In FIG. 1, the outer edge of the scanning region R0 is schematically shown by a dashed line.

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

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

[0022] Furthermore, when a virtual plane R1 is defined as a plane located a predetermined distance from the deflection element 16 within the scanning region R0, the scanning region R1 can be defined as a two-dimensional region extending along the first direction D1 and the second direction D2. The third-order light L3 is projected toward the scanning region R0 so as to scan this scanning region 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] Furthermore, as shown in Figure 1, if an object OB (i.e., an object or substance that reflects or scatters the secondary light L2) is present in the scanning region R0, the tertiary light L3 is reflected or scattered by the object OB. A portion of the tertiary light L3 reflected by the object OB travels as quaternary light (hereinafter sometimes referred to as reflected light) L4 along almost 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 is provided on the optical path of the fourth-order light L4, and in this embodiment, on the optical path common to the second-order light L2 and the fourth-order light L4 between the deflection element 16 and the light projection optical system 15 (light shielding part 13), and has a deflection element (second deflection element) 17 that deflects the fourth-order light L4. For example, the deflection element 17 is an optical 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 in this embodiment, it is a beam splitter.

[0025] In other words, in this embodiment, the deflection element 16 is a movable deflection element for scanning that deflects the secondary light L2 in a variable direction when it operates. On the other hand, the deflection element 17 is a fixed 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 focuses and shapes the fourth-order light L4. The light-receiving optical system 18 includes, for example, at least one lens.

[0027] Furthermore, the distance measuring device 10 has a photodetector (second photodetector) 19 that receives the fourth-order light L4. The photodetector 19 is positioned, for example, at the focal point of the fourth-order light L4 focused by the photodetector optical system 18. For example, the photodetector 19 has at least one detection element that detects the fourth-order light L4 and generates an electrical signal corresponding to the fourth-order light.

[0028] The light-receiving element 19 generates the electrical signal as the detection result (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 the scanning result of the scanning region R0.

[0029] The distance measuring device 10 has a control unit 20 that drives and controls a light source 11, a light receiving element 14, a deflection element 16, and a 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 portion 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 includes a distance measuring unit 23 that measures the distance to the target object OB based on the reception result of the fourth-order light L4 by the light-receiving element 19. In this embodiment, the distance measuring unit 23 detects a pulse indicating the fourth-order light L4 from the electrical signal. The distance measuring unit 23 also measures the distance to the target object OB (or a part of its surface area) using the time-of-flight method based on the time difference between the emission timing of the third-order light L3 and the reception timing of the fourth-order 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 of the scanning area R0 (distance measuring image) that shows the distance measurement result (distance value) of each of the plurality of distance measuring points as pixels. In this embodiment, the distance measuring unit 23 associates information indicating the distance measuring points with the displacement of the rotating mirror 16A and generates image data showing a two-dimensional map or a three-dimensional map of the scanning area R0.

[0032] Furthermore, the distance measuring unit 23 uses, for example, the period of change in the projection direction of the third light L3, i.e., the scanning period which is the period of scanning the scanning area R0, as the generation period for the distance measuring image, and generates one distance measuring image for each scanning period.

[0033] The scanning period refers to the time it takes for a predetermined displacement of the rotating mirror 16A to return to that predetermined displacement, for example, 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 multiple distance measuring images as a video in chronological order.

[0034] Figure 2 is a schematic diagram showing the light-emitting 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 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 short direction. Furthermore, each of the laser bars E1 to E3 is aligned along the second direction D2 and emits laser beam along optical axes that extend parallel to each other.

[0036] The light source 11 emits the entirety of the 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 linear cross-sectional shape with a first direction D1 and a second direction D2 as its longitudinal and short directions, respectively.

[0037] Figure 3 schematically shows the configuration of the light-shielding section 13 and the cross-sectional shape of the secondary light L2 generated by the light-shielding section 13. As shown in Figure 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 in which the first direction D1 and the second direction D2 are the longitudinal and short directions, 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] In other words, in this embodiment, the light source 11 emits multiple beams of light as primary laser beams L11, L12, and L13, each having a cross-sectional shape with a longitudinal direction and a transverse direction, and arranged along the transverse direction.

[0039] Furthermore, in this embodiment, the light-shielding portion 13 is positioned at a location where the image (intermediate image) L1P of the light-emitting surface 11A of the primary light L1 at the light source 11 is imaged by the imaging optical system 12. Figure 3 schematically shows the images of each of the light-emitting surfaces of the primary laser light L11 to L13 that constitute the image L1P.

[0040] Furthermore, the primary laser beams L11, L12, and L13 that have passed through the light-shielding section 13 pass through the light-shielding section 13 again as secondary laser beams L21, L22, and L23, respectively. The secondary beam L2 includes these three secondary laser beams L21, L22, and L23. In addition, the secondary beam L2 as a whole has a linear cross-sectional shape with a first direction D1 and a second direction D2 as its longitudinal and short directions, respectively.

[0041] Furthermore, as shown in Figure 3, in this embodiment, the light-shielding portion 13 is configured and positioned to shield each end of the primary laser beams L11 to L13. In addition, 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, that is, the primary laser beams L11 to L13 that have passed through the light-shielding portion 13, are aligned along the first direction D1.

[0042] Therefore, each of the secondary laser beams L21 to L23 has a cross-sectional shape in which the length in the longitudinal direction and the position of the ends in the longitudinal direction are aligned. Consequently, the secondary beam L2 is projected as light with a rectangular outer shape in which the outer edge in the longitudinal direction is clearly defined.

[0043] Here, we will explain the primary light L1 and secondary light L2. For example, if we want to increase the distance that the distance measuring device 10 can measure, we can consider increasing the intensity of the light emitted as the tertiary light L3. And, considering the emission of high-intensity primary light L1, we can consider using a high-power light source as the light source 11.

[0044] Furthermore, considering the simultaneous acquisition of fourth-order light L4 from multiple regions within the scanning region R0, it is conceivable to use a laser element consisting of stacked laser bars E1 to E3 as described above as the light source 11. This makes it possible to obtain high-power, linear third-order light L3 while suppressing the 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, as shown in Figure 2 for example, the longitudinal lengths (bar lengths) of the laser bars E1 to E3 are slightly different. For example, the bar length of laser bar E1 is the longest, and the bar length of laser bar E3 is the largest.

[0046] In this case, as shown in Figure 3, of the primary laser beams L11 to L13, primary laser beam L11 has the shortest beam shape, and primary laser beam L13 has the longest beam shape. The primary light L1, consisting of these primary laser beams L11 to L13, has different intensities overall between the central part and the edges 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 edge of the first direction D1 of the primary light L1 may not have sufficient intensity. Consequently, if this primary light L1 is projected as the tertiary light L3, there may be areas within the scanning area R0 that are illuminated with sufficient tertiary light L3 and areas that are not illuminated with sufficient tertiary light L3. Consequently, there may be inconsistencies in the distance measurement accuracy within the scanning area R0, or areas where the measurable distance is shorter than in other areas.

[0048] In contrast, in this embodiment, a light-shielding portion 13 is provided to shield the ends of each 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 overall intensity of the secondary beam L2 along the first direction D1 is made uniform. Consequently, the amount of tertiary beam L3 projected onto the scanning area R0 is made uniform, enabling stable and accurate scanning and distance measurement across the entire scanning area R0.

[0049] Furthermore, in this embodiment, only a portion of the primary light L1 is emitted as secondary light L2. That is, secondary light L2 has a lower intensity than primary light L1. In response to this, the light source control unit 21 of the control unit 20 controls the intensity of primary light L1, i.e., the output of the light source 11, so that the secondary light L2 reaches the designed light quantity. In other words, the light source 11 emits primary light L1 at an output based on the light quantity of secondary light L2, which is primary light L1 that has passed through the light shielding unit 13.

[0050] More specifically, for example, the light source 11 emits laser light as the primary light L1. Furthermore, the distance measuring device 10 is envisioned to be mounted on a moving object such as a vehicle, and to perform distance measurement over various spaces with a scanning area R0. In this case, it is conceivable that the laser light may be shone onto a person. Therefore, it is necessary to consider the upper limit of the intensity of the laser light that can be emitted 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 intensity of the third light L3 based on the light intensity of the second light L2. In other words, the output control of the light source 11 is performed by considering the second light L2, which has an intensity closer to that of the third light L3 than that of the first light L1. Therefore, the third light L3 can be projected while satisfying the output limit of the laser light and performing appropriate output adjustment.

[0052] In this embodiment, the light-shielding portion 13 is reflective to the primary light L1. A light-receiving element 14 is also 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 light-receiving result of the reflected primary light L1R by the light-receiving element 14.

[0053] In other words, if the light-shielding portion 13 reflects a portion 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. To put it another way, if the light-shielding portion 13 is reflective to the primary light L1, a monitoring unit 22 can be provided to receive the primary light L1 reflected by the light-shielding portion 13 and monitor the primary light L1 (for example, the amount of light of the primary light L1), thereby giving the distance measuring device 10 a monitoring function with a simple configuration.

[0054] Figure 4 is a schematic diagram showing the light-receiving surface 19R of the light-receiving element 19. As shown in Figure 4, the light-receiving element 19 has a light-receiving surface 19R consisting 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 each of the light-receiving segments 19A is arranged in a single row, and has a line-shaped light-receiving surface 19R.

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

[0056] Figure 5 shows an example configuration of the light-receiving optical system 18 and the light-receiving element 19. In this embodiment, the light-receiving optical system 18 focuses the fourth-order light L4 so that it is incident on the entire first direction D1 on the light-receiving surface 19R of the light-receiving element 19. Consequently, 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 of the light-receiving segments 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 focusing characteristics that maximize 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 section 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-shielding portion 13 that shields the end of the primary light L1 in the first direction D1 from the light source 11 that emits primary light L1 having a cross-sectional shape with the first direction D1 as the longitudinal direction. Therefore, the light at the end of the primary light L1, that is, the emission of light with low intensity in the primary light L1, is blocked. Consequently, it becomes possible to emit secondary light L2 with reduced intensity unevenness, enabling accurate scanning and distance measurement.

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

[0060] For example, the light source 11 may be configured to emit multiple beams of light (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 transverse 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 multiple primary laser beams L11 to L13. For example, the light source 11 may be configured to emit only one primary laser beam (e.g., only primary laser beam L12) as primary beam L1.

[0062] Specifically, when projecting primary light L1, which has a linear cross-sectional shape, the edges of the primary light L1 may have a lower intensity than the central part. Also, the intensity of the edges of the primary light L1 may be less stable than that of the central part. Thus, the characteristics of the edges of the primary light L1 may be more unstable than those of the central part. Therefore, it is preferable to project only the central part of the primary light L1. Accordingly, by shielding the edges 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] Furthermore, in this embodiment, the case in which the light-shielding portion 13 is configured to shield each of the ends of the primary laser beams L11 to L13 has been described. However, the configuration of the light-shielding portion 13 is not limited to this. The light-shielding portion 13 only needs to be configured to shield at least one end of the primary laser beams L11 to L13.

[0064] Furthermore, when the light source 11 emits primary light L1 consisting of multiple beams of light (for example, primary laser beams L11 to L13), as described above, it is preferable that the light shielding portion 13 is configured to shield the end of at least one of the multiple beams of light in the first direction D1 so that the lengths of the beams that have passed through the light shielding portion 13 (and are not shielded by the light shielding portion 13) in the first direction D1 are uniform.

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

[0066] Furthermore, in this embodiment, the case in which the light-shielding portion 13 is reflective to the primary light L1 has been described. However, the light-shielding portion 13 only needs to be configured to shield (prevent from emitting) the end of the primary light L1 in the first direction D1. For example, the light-shielding portion 13 may be absorbing to the primary light L1.

[0067] Furthermore, if the light-shielding portion 13 does not reflect the primary light L1, the light-receiving element 14 may not be provided. In this case, the light source 11 can be monitored by other general means without using the light-shielding portion 13.

[0068] Furthermore, in this embodiment, the case in which the light-shielding portion 13 consists of a light-shielding plate having an opening in 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-shielding portion 13 is not limited to this. For example, the light-shielding portion 13 may have a transparent portion that transmits the primary light L1 in the optical path of the central part of the primary light L1, and the other part may be a light-shielding plate with light-shielding properties. Also, the light-shielding portion 13 may have multiple light-shielding plates.

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

[0070] In this embodiment, an imaging optical system 12 is provided to form an image L1P of the primary light L1, and the light-shielding portion 13 is positioned where the image L1P of the primary light L1 is formed. However, the position of the light-shielding portion 13 is not limited to this.

[0071] For example, the distance measuring device 10 does not have to have an imaging optical system 12. Also, the light shielding part 13 may be located in the immediate vicinity of the light emission surface 11A of the light source 11. That is, the primary light L1 may be configured so that a portion of it is shielded by the light shielding part 13 immediately after it is emitted from the light source 11.

[0072] Furthermore, considering the need to reliably shield the end of the primary light L1, it is preferable to position the imaging optical system 12 and then position the light-shielding portion 13 at the imaging position of the image L1P on the light-emitting surface 11A of the light source 11. Specifically, if the light-shielding portion 13 is positioned anywhere other than the imaging position of the image L1P, the end of the primary light L1 that passes through the light-shielding portion 13 may not be reliably shielded.

[0073] In other words, the distance measuring device 10 is preferably provided on the optical path of the primary light L1 between the light source 11 and the light shielding part 13, and has an imaging optical system 12 that forms an image L1P of the light emitting surface 11A of the light source 11. Furthermore, it is preferable that the light shielding part 13 is positioned where this image L1P is formed.

[0074] Furthermore, in this embodiment, the case described was one in which the light source control unit 21 of the control unit 20 controls the light source 11 to emit primary light L1 with an intensity corresponding to the amount of secondary light L2. However, the light source 11 only needs to be configured to emit primary light L1 in a predetermined manner, or to allow adjustment of the emission manner of primary light L1.

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

[0076] Furthermore, the distance measuring device 10 includes a light-receiving element 19 that receives reflected light (4th-order light L4), which is light (3rd-order light L3) reflected by the object OB, and has a light-receiving surface 19S consisting 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 emitting light with reduced intensity unevenness.

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

[0078] Furthermore, the distance measuring device 10 does not necessarily have a deflection element 16 in addition to the distance measuring unit 23. In this case, for example, the light source 11, light shielding unit 13, and light receiving element 19 in the distance measuring device 10 function as a non-scanning type light transmitting and receiving device. Even in this case, light transmitting and receiving can be performed using, for example, light of uniform intensity. In other words, the present invention can also be implemented as a light transmitting and receiving device capable of accurate light transmitting and receiving by transmitting light with reduced intensity unevenness.

[0079] Furthermore, the distance measuring device 10 does not necessarily have a light-receiving element 19. In this case, the light source 11 and the light shielding part 13 function as a light-emitting device. In this case, for example, it is possible to emit light of uniform intensity. That is, the present invention can also be implemented as a light-emitting device capable of emitting light with reduced intensity unevenness.

[0080] As described above, for example, the light projection device in this embodiment includes a light source 11 that emits light (primary light L1) with a cross-sectional shape having a longitudinal direction (first direction D1) and a transverse direction (second direction D2), and a light shielding part 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 part

Claims

[Claim 1] A light source that emits light with a cross-sectional shape having a longitudinal direction and a transverse direction in a cross section perpendicular to the direction of travel, A light projection device characterized by having a light-shielding portion that shields the longitudinal end of the light.

Images