OPTICAL SCANNING DEVICE AND OBJECT DETECTION DEVICE

Abstract

Provision is made for an optical scanning device capable of significantly changing the field of view during optical scanning, and for an object detection device that incorporates this capability. An optical scanning device used in a device that detects an object by emitting emitted light and receiving reflected light, the optical scanning device comprising: a deflector; at least one light source; a variable polarizing element arranged to receive light emitted by the light source and to emit either a first emission light consisting mainly of a first light in a first polarization state, or a second emission light consisting mainly of a second light in a second polarization state different from the first polarization state; a branching element that splits the first light and the second light in different directions; and an optical system that causes the first light split by the branching element to beThe second light, which was branched off, strikes the deflector at a first angle and causes the second light, which was branched off by the branching element, to strike the deflector at a second angle that differs from the first angle.

Description

TECHNICAL AREA

[0001] The present disclosure relates to an optical scanning device and an object detection device. TECHNICAL BACKGROUND

[0002] A prior art optical scanning device and object detection device is described, for example, in the unexamined Japanese patent application with publication number 2010-151958 (patent document 1). DOCUMENT OF THE STATE OF THE TECHNOLOGY PATENT DOCUMENT

[0003] [Patent document 1] Unexamined Japanese patent application with publication number 2010-151958 SUMMARY OF THE INVENTIONAL PROBLEM

[0004] In one specific aspect, an objective of the present disclosure is to provide an optical scanning device capable of significantly changing the field of view during optical scanning, and an object detection device that incorporates this capability. SOLUTION TO THE PROBLEM

[0005] (1) An optical scanning device according to one aspect of the present disclosure is an optical scanning device used in a device which detects an object by emitting an outgoing light and receiving a reflected light, wherein the optical scanning device comprises: a deflector; at least one light source; a variable polarizing element arranged to receive light emitted by the light source, and which either emits a first emission light consisting mainly of a first light in a first polarization state, or emits a second emission light consisting mainly of a second light in a second polarization state that differs from the first polarization state; a branching element which splits the first light and the second light in different directions; and an optical system which causes the first light, which has been split or diverted by the branching element, to strike the deflector at a first angle, and which causes the second light, which is diverted by the branching element, to strike the deflector at a second angle which differs from the first angle.

[0006] (2) An object detection device according to one aspect of the present disclosure is an object detection device comprising the following: the optical scanning device as described in point (1) above; a light receiving unit which detects the reflected light from the emitted light emitted by the optical scanning device and which generates a light receiving signal corresponding to the intensity of the reflected light; and a control unit configured to control the operation of the optical scanning device and to generate point group information based on the light reception signal.

[0007] According to the above configurations, it is possible to provide an optical scanning device capable of significantly changing the field of view during optical scanning, and an object detection device that incorporates this capability. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is an illustration that shows a configuration of an object detection device according to an exemplary embodiment. Fig. Figure 2 is an illustration to explain an optical configuration of a scanning light source unit. Fig. Figure 3(A) is a figure illustrating the layout of the optical configuration in the xy-plane when the first optical path is used. Fig. Figure 3(B) is a figure illustrating the layout of the optical configuration in the xz-plane when the first optical path is used. Fig. Figure 4(A) is a figure illustrating the layout of the optical configuration in the xy-plane when the second optical path is used. Fig. Figure 4(B) is an illustration showing the layout of the optical configuration in the xz-plane when the second optical path is used. Fig. Figure 5(A) is an illustration to explain the field of view when the first optical path is used. Fig. Figure 5(B) is an illustration to explain the field of view when the second optical path is used. Fig. Figure 6(A) is a figure illustrating the field of view formed on both sides of the normal or perpendicular line c of a MEMS mirror when the first optical path is used. Fig. Figure 6(B) is a figure illustrating the field of view formed on both sides of the normal or perpendicular line c of a MEMS mirror when the second optical path is used. Fig. 7(A) and Fig. Figure 7(B) are illustrations that demonstrate the field of view of a modified example. Fig. Figure 8 is a flowchart illustrating an operating procedure of the object detection device 1 when the field of view is set in a variable manner according to the vehicle speed. Fig. 9(A) and Fig. Figure 9(B) shows an example configuration of an object detection device according to a modified example. Fig. 10(A) and Fig. Figure 10(B) shows an example configuration of an object detection device according to a modified example. WAY TO IMPLEMENTING THE INVENTION

[0008] Fig. Figure 1 illustrates a configuration of an object detection device according to an exemplary embodiment. The object detection device 1 according to this exemplary embodiment uses a plurality of laser lights (detection lights) to perform an optical scanning of a target space, receives reflected light, and uses the reflected light to detect point group information indicating the position and relative distance of an object present in the target space. The object detection device 1 is configured to include a control unit (control device) 10, a scanning light source unit (an optical scanning device) 20, and a light receiving unit 30. The object detection device 1 is, for example, mounted on a vehicle and used to detect objects around the vehicle (other vehicles, pedestrians, etc.).). In this case, the object detection device 1 can, for example, be attached to the roof of a vehicle, near an emblem or license plate, near a rearview mirror, or in a headlight or similar device.

[0009] The control unit 10 controls the overall operation of the object detection device 1 and is configured to include a measurement control unit 11, a deflection control unit 12, a polarization control unit 13, an illumination control unit 14, a distance measurement unit 15, and a communication unit 16. This control unit 10 can be implemented using a computer system comprising a CPU (central processing unit), ROM (read memory), RAM (main memory), and so on, and causes the computer system to execute a predetermined operating program.

[0010] The measurement control unit 11 controls the operation of the deflection control unit 12, the polarization control unit 13, the illumination control unit 14 and the distance measuring unit 15, and also controls the communication unit 16 to transmit point group information, which is a measurement result of the distance measuring unit 15, to an external device not shown.

[0011] The deflection control unit 12 controls a MEMS mirror 22 via a MEMS driver 21, the scanning light source unit 20, so that the MEMS mirror 22 deflects periodically in a defined angle change pattern (typically in a raster scan with uniform scan line intervals).

[0012] The polarization control unit 13 controls the operation of each variable polarization element 24a, 24b via a driver 23 for the variable polarization element.

[0013] The lighting control unit 14 controls a light source driver 25 such that each light source 26a, 26b emits laser light according to the pulse condition instructed by the measurement control unit 11.

[0014] The distance measuring unit 15 uses the generation instruction time of the laser light from the illumination control unit 14 and the light reception signal received by a light receiving circuit 34 of the light receiving unit 30 to measure a distance between or to the object in the target space based on the time difference between the emission time and the reception time of the laser light. Based on the emission time and the reception time of the laser light, the three-dimensional position of the object is further detected by the measurement control unit 11.

[0015] The communication unit 16 transmits the received point group information (a set of three-dimensional positions) to an external device (not shown). Furthermore, the communication unit 16 receives vehicle speed information from a vehicle control device (not shown).

[0016] The scanning light source unit 20 generates a narrow-angle beam of laser light and emits the laser light in different directions within a predetermined area and is configured to include a MEMS driver (a second driver) 21, a MEMS mirror 22, a variable polarization element driver (a third driver) 23, two variable polarization elements 24a, 24b, a light source driver (a first driver) 25 and two light sources 26a, 26b.

[0017] The MEMS driver 21 is connected to the MEMS mirror 22 and, under the control of the deflection control unit 12 of the control unit 10, generates a drive signal to control the operation of the MEMS mirror 22 and supplies the drive signal to the MEMS mirror 22.

[0018] The MEMS mirror 22 is a two-dimensional deflector with a reflective surface configured to rotate in either of two orthogonal directions. This MEMS mirror 22 is positioned so that the laser light emitted by the respective light sources 26a and 26b can enter or strike the reflective surface from different directions. It rotates based on the drive signal supplied by the MEMS driver 21 to scan each laser light within the target space. Each laser light is emitted from an aperture appropriately provided in the scanning light source unit 20, towards an external target or target space.

[0019] The driver 23 for the variable polarization element is connected to each variable polarization element 24a, 24b, and under the control of the polarization control unit 13 of the control unit 10 generates a drive signal which controls the operation of each variable polarization element 24a, 24b and supplies the drive signal to each variable polarization element 24a, 24b.

[0020] Each variable polarizing element 24a, 24b is an element capable of rotating the polarization direction (polarization plane) of the incident light. For example, a liquid crystal polarizing rotation element or an electro-optic modulator can be used as such a variable polarizing element 24a, 24b. The rotation angle of the polarization direction can be controlled by the magnitude of the voltage applied to each variable polarizing element 24a, 24b by the variable polarizing element driver 23. The variable polarizing elements 24a, 24b are arranged such that light emitted by the light source strikes them and emits either light consisting mainly of a first light in a first polarization state or light consisting mainly of a second light in a second polarization state that differs from the first polarization state.For example, the variable polarization elements 24a, 24b emit emission light which has 95% or more of the first light in the first polarization state, or emission light which has 95% or more of the second light in the second polarization state, which differs from the first polarization state.

[0021] The light source driver 25 is connected to each light source 26a, 26b and, under the control of the lighting control unit 14 of the control unit 10, generates a drive signal to control the operation of each light source 26a, 26b and supplies the drive signal to each light source 26a, 26b.

[0022] Each light source 26a, 26b generates laser light with a narrow-angle beam (a beam with a small divergence angle) as detection light and emits the laser light. The laser light emitted by each light source 26a, 26b is a beam with a spreading angle comparable to (equal to or less than) the angular resolution of the object detection device 1. For example, a near-infrared photonic crystal laser (PCSEL) can be used as each of the light sources 26a, 26b; however, the present disclosure is not limited to this, and it can be any light source capable of emitting narrow-angle detection light.

[0023] The light receiving unit 30 receives reflected light generated by the laser light emitted by the light sources 26a and 26b and generates a light receiving signal. It is configured to include a lens 31, an optical filter 32, a photodetector (light receiving element) 33, and a light receiving circuit 34. This light receiving unit 30 can be configured as a coaxial optical system, receiving light along the same optical path as the optical path from each light source 26a, 26b to the MEMS mirror 22, or it can be configured as a non-coaxial optical system, not using the same optical path.

[0024] The lens 31 condenses or focuses the reflected light generated by the laser light emitted by the light sources 26a and 26b. The optical filter 32 blocks light with a wavelength region different from that of the laser light emitted by each light source 26a, 26b, and allows light with the same wavelength region as that of the laser light emitted by each light source 26a, 26b to pass through. The photodetector 33 detects the light incident through the optical filter 32.

[0025] The light receiving circuit 34 generates a light receiving signal by applying a predetermined signal processing (for example, amplification, frequency filtering, or similar) to the output of the photodetector 33. The generated light receiving signal is supplied to the distance measuring unit 15 of the control unit 10.

[0026] Fig. Figure 2 illustrates an optical configuration of a scanning light source unit. The laser light emitted by the light source 26a, for example, is p-polarized and is emitted parallel to the y-axis shown in the figure, striking the variable polarization element 24a. The variable polarization element 24a does not rotate the polarization direction when the voltage is "OFF" and rotates the polarization direction by 90° when the voltage is "ON". Therefore, when the voltage is "OFF", the p-polarized laser light striking the variable polarization element 24a passes through it in its original polarization direction and strikes a polarization beam splitter (branching element) 40a.This p-polarized laser light passes through the polarization beam splitter 40a, strikes a mirror 41a, is reflected by the mirror 41a, and enters a MEMS mirror 22. The laser light striking the MEMS mirror 22 is reflected by the MEMS mirror 22.

[0027] Conversely, when the voltage is "ON", the p-polarized laser light striking the variable polarizing element 24a becomes s-polarized light, with its polarization direction rotated by 90°. It passes through the variable polarizing element 24a and enters the polarizing beam splitter 40a. This s-polarized laser light is reflected by the polarizing beam splitter 40a in a direction parallel to the x-axis, strikes a mirror 42a, is reflected by the mirror 42a, is further reflected by a mirror 43a, and enters the MEMS mirror 22. The laser light striking the MEMS mirror 22 is reflected by the MEMS mirror 22.

[0028] This means that in the scanning light source unit 22 of the present embodiment, two optical paths can be used selectively, depending on the voltage applied to the variable polarization element 24a, thereby variably determining the polarization direction of the laser light: a first optical path (shown by a solid line in the figure) which runs through the polarization beam splitter 40a and the mirror 41a to the MEMS mirror 22; and a second optical path (shown by a dashed line in the figure) which runs through the polarization beam splitter 40a, the mirror 42a and the mirror 43a to the MEMS mirror 22.

[0029] Similarly, the laser light emitted by the light source 26b is, for example, p-polarized light, and it is emitted parallel to the y-axis, as shown in the figure, and it strikes a variable polarizing element 24b. The variable polarizing element 24b does not rotate the polarization direction when the voltage is "OFF" and rotates the polarization direction by 90° when the voltage is "ON". Therefore, when the voltage is "OFF", the p-polarized laser light striking the variable polarizing element 24b passes through the variable polarizing element 24b in its original polarization direction and strikes a polarizing beam splitter (branching element) 40b. This p-polarized laser light passes through the polarizing beam splitter 40b, strikes a mirror 41b, is reflected by the mirror 41b, and enters a MEMS mirror 22.The laser light that hits the MEMS mirror 22 is reflected by the MEMS mirror 22.

[0030] When the voltage is "ON", the p-polarized laser light striking the variable polarizing element 24b becomes s-polarized light, with its polarization direction rotated by 90°. It passes through the variable polarizing element 24b and enters the polarizing beam splitter 40b. This s-polarized laser light is reflected by the polarizing beam splitter 40b in a direction parallel to the x-axis, strikes a mirror 42b, is reflected by the mirror 42b, is further reflected by a mirror 43b, and strikes the MEMS mirror 22. The laser light striking the MEMS mirror 22 is reflected by the MEMS mirror 22.

[0031] This means that in the scanning light source unit 20 of the present embodiment, two optical paths can be used selectively, depending on the voltage applied to the variable polarization element 24b, which determines the polarization direction of the laser light: a first optical path (shown by a solid line in the figure) that passes through the polarization beam splitter 40b and the mirror 41b to the MEMS mirror 22; and a second optical path (shown by a dashed line in the figure) that passes through the polarization beam splitter 40b, the mirror 42b and the mirror 43b to the MEMS mirror 22.

[0032] Mirrors 41a, 42a, and 43a are fixedly arranged such that light emitted by the light source 26a and passing through the variable polarizing element 24a strikes the MEMS mirror 22. Mirrors 41b, 42b, and 43b are fixedly arranged such that light emitted by the light source 26b and passing through the variable polarizing element 24b strikes the MEMS mirror 22.

[0033] Mirror 41a and mirror 41b are arranged at positions where the angle at which the light reflected from each mirror strikes MEMS mirror 22a is essentially symmetrical with respect to the center of MEMS mirror 22 in the x-axis direction.

[0034] Furthermore, mirror 43a and mirror 43b are arranged at positions where the angle at which the light reflected from each mirror hits the MEMS mirror 22a is essentially symmetrical with respect to the center of the MEMS mirror in the x-axis direction.

[0035] Fig. Figure 3(A) is a diagram showing the arrangement of the optical configuration in the xy-plane when the first optical path is used. Furthermore, Fig. 3(B) is a figure showing the arrangement of the optical configuration in the xz-plane when the first optical path is used. Here in Fig. Figure 3(A) shows the light ray reflected by mirror 22 at an angle for convenience; however, the light ray actually travels forward to the front surface of the paper. Furthermore, for easier understanding, the Fig. 3(B) only the path from mirror 41a to MEMS mirror 22. Furthermore, the first optical path that reaches MEMS mirror 22 via polarization beam splitter 40a and mirror 41 is illustrated here, and the same applies to the first optical path that reaches MEMS mirror 22 via polarization beam splitter 40b and mirror 41b, and thus the illustration and description of it are omitted.

[0036] When the first optical path is used, as described above, the p-polarized laser light emitted by the light source 26a passes through the variable polarization element 24a while maintaining the polarization direction, passes through the polarization beam splitter 40a, hits the mirror 41a, is reflected by the mirror 41a and enters the MEMS mirror 22 (see Fig. 3(A)). The relative arrangement of the mirror 41 and the MEMS mirror 22 is such that the laser light incident from the mirror 41a onto the MEMS mirror 22 strikes the reference position of the MEMS mirror 22 at an angle of incidence θ1 with respect to the perpendicular direction (see Fig. 3(B)). The laser light which strikes the MEMS mirror 22 is reflected by the MEMS mirror 22.

[0037] Fig. Figure 4(A) is a diagram illustrating the arrangement of the optical configuration in the xy-plane when the second optical path is used. Furthermore, Fig. Figure 4(B) illustrates the arrangement of the optical configuration in the xz-plane when the second optical path is used. Here in Fig. Figure 4(A) shows the light ray reflected by mirror 22, shown obliquely for simplification; however, the light ray actually travels towards the front of the paper surface. Furthermore, Figure 4(A) shows the light ray reflected by mirror 22. Fig. 4(B) For the sake of simplicity, only the path from mirror 43a to MEMS mirror 22 is shown. Furthermore, the second optical path, which reaches MEMS mirror 22 via polarization beam splitter 40a and mirror 42a, is illustrated here, and the same applies to the second optical path, which reaches MEMS mirror 22 via polarization beam splitter 40b and mirror 42b, and therefore its representation and description are omitted.

[0038] When the second optical path is used, as described above, the p-polarized laser light emitted by the light source 26a is rotated by 90° in the polarization direction by the variable polarizing element 24a, so that it becomes s-polarized light. It passes through the variable polarizing element 24a, is reflected by the polarizing beam splitter 40a, strikes the mirror 42a, is reflected by the mirror 42a, strikes the mirror 43a, is reflected by the mirror 43a, and enters the MEMS mirror 22 (see Fig. 4(A)). The relative arrangement of the mirror 43a and the MEMS mirror 22 is such that the laser light incident from the mirror 43a onto the MEMS mirror 22 strikes the reference position of the MEMS mirror 22 at an angle of incidence θ2 (< θ1) with respect to the perpendicular direction (see Fig. 3(B)). The laser light which strikes the MEMS mirror 22 is reflected by the MEMS mirror 22.

[0039] Fig. Figure 5(A) is an illustration to explain the field of view when the first optical path is used. Furthermore, Fig. Figure 5(B) illustrates the field of view when the second optical path is used. As described above, in the present embodiment, the arrangement of the optical configuration is such that the angle of incidence θ2 of the laser light striking the MEMS mirror 22 when the second optical path is used is comparatively smaller than the angle of incidence θ1 of the laser light striking the MEMS mirror 22 when the first optical path is used.

[0040] When the first optical path is used, a relatively wide field of view (FOV) can be formed with respect to the angle of incidence θ1, for example, by setting the optical deflection angle θxsc1 in the x-axis direction of the MEMS mirror 22 to twice the angle θ1. The field of view formed here is theoretically fan-shaped in a region at the top of the figure, from the perpendicular line c of the MEMS mirror 22, as shown in the figure. Similarly, the field of view formed by using the laser light emitted by the light source 26b is theoretically fan-shaped in a region at the bottom of the figure, from the perpendicular line c of the MEMS mirror 22. As an example, θ1 can be set to 15° and θxsc1 can be set to 30°.

[0041] When the second optical path is used, a field of view (FOV) with a relatively narrow area can be formed with respect to the angle of incidence θ2, for example, by setting the optical deflection angle θxsc2 in the x-axis direction of the MEMS mirror 22 to twice the angle θ2. The field of view formed here is theoretically fan-shaped in a region on the upper side of the figure, from the perpendicular line c of the MEMS mirror 22, as shown in the figure. Similarly, the field of view formed by using the laser light emitted by the light source 26b is theoretically fan-shaped in a region on the lower side of the figure, from the perpendicular line c of the MEMS mirror 22. As an example, θ2 can be set to 7.5° and θxsc2 can be set to 15°.

[0042] Fig. Figure 6(A) is a figure illustrating a field of view (FOV) formed on both sides of the perpendicular line c of the MEMS mirror when the first optical path is used. Fig. 6(A) shows above the vertical line c the field of view formed by the first optical path in which light is emitted from the light source 26a and enters the MEMS mirror 22 via the mirror 41a, and below the vertical line c shows the field of view formed by the first optical path in which light is emitted from the light source 26b and enters the MEMS mirror 22 via the mirror 41b.

[0043] Fig. Figure 6(B) is a diagram illustrating the field of view (FOV) formed on both sides of the perpendicular line c of the MEMS mirror when the second optical path is used. Fig. 6(B) shows above the vertical c the field of view formed by the second optical path in which light passes through mirror 43a onto MEMS mirror 22, and below the vertical c shows the field of view formed by the second optical path in which light passes through mirror 43b onto MEMS mirror 22.

[0044] In Fig. 6(A) the field of view formed by the first optical path which strikes the MEMS mirror 22 via the mirror 41a and the field of view formed by the first optical path which strikes the MEMS mirror 22 via the mirror 41b are shaped such that they are continuous or continuous without any gap.

[0045] Furthermore, in Fig. 6(B) the field of view formed by the second optical path which strikes the MEMS mirror 22 via the mirror 43a, and the field of view formed by the second optical path which strikes the MEMS mirror via the mirror 43b, such that they are continuous or continuous without any gap.

[0046] Even if the field of view, which is formed by the two light sources 26a and 26b, is formed either by the first optical path or by the second optical path, the field of view can therefore be formed continuously or throughout without any gap.

[0047] As shown in each figure, the field of view is relatively wide when the first optical path is used, while it is relatively narrow when the second optical path is used. As long as the number of hitting points per frame or image capture of the laser light remains constant, the angular resolution is consequently comparatively higher when the second optical path is used than when the first optical path is used.

[0048] For example, assuming that the MEMS mirror 22 is a biaxial MEMS mirror with a resonant axis and a non-resonant axis, where the resonant axis is the x-axis and the non-resonant axis is the y-axis, and whether either the first or the second optical path is used, the frequency of the resonant axis is 22 kHz and the frequency of the non-resonant axis is 120 Hz. Furthermore, it is assumed that twice the mechanical deflection angle of the MEMS mirror 22 is the optical deflection angle. If the first optical path is used, assuming the optical deflection angle of the x-axis θxsc = 30°, then in this case the optical deflection angle of the y-axis θysc = 20°, and the number of hitting points per frame is 120,000 points, resulting in an angular resolution of 0.1°.If the second optical path is still used, assuming that the optical deflection angle of the x-axis θxsc = 15°, the optical deflection angle of the y-axis θysc = 20°, and the number of hitting points per frame or shot is 120,000 points, then the angular resolution will be 0.05°.

[0049] Thus, a scenario is assumed in which the object detection device 1 of the present embodiment is attached to a vehicle, as described above. For example, if the vehicle speed is high, it is desirable to be able to detect an object at a greater distance, but a narrow detection range is acceptable, and therefore it is preferable to use the second optical path, which has a narrow field of view and high angular resolution. Conversely, if the vehicle speed is low, a wider detection range is better, and therefore it is preferable to use the first optical path, which has a wide field of view and low angular resolution.Regardless of which optical path is used, in this case the field of view can be shaped without any gaps on any side of the perpendicular c of the MEMS mirror 22, as shown in each figure, so that it can be prevented that a non-detectable area is created.

[0050] This means that by configuring the first and second optical paths so that they are switchable, it is possible to switch between wide and narrow viewing angles without gaps. On the other hand, for example, in a case where a configuration is used without a variable polarization element or similar, and where two light sources each strike the MEMS mirror via only one optical path, a gap will appear in the viewing field in the central region containing the perpendicular c in a predetermined area where the deflection angle is small, even if the width is adjusted depending on the size of the MEMS mirror's deflection angle.

[0051] As in the modified example in Fig. 7(A) and Fig. As shown in Figure 7(B), by adjusting the optical deflection angle of the MEMS mirror 22, the field of view formed by the laser light from each light source 26a, 26b can be set so that it partially overlaps the region enclosing the perpendicular line c. Patterns have been added to the figures to make each field of view easier to understand.

[0052] Fig. Figure 8 is a flowchart illustrating the operating procedure of an object detection device 1 when the field of view is variably set according to the vehicle speed. It should be noted that the sequence of the processes shown here can be changed as long as no contradiction or inconsistency arises in the result of the information processing, and other processes or steps not explicitly described here can also be added.

[0053] When the vehicle is started by switching on the ignition, etc., the measurement control unit 11 of the control unit 10 initiates object detection in a low-speed mode, which is a measurement mode that uses the first optical path (step S11). Specifically, the measurement control unit 11 controls the driver 23 for the variable polarization element by sending a command to the polarization control unit 13, and it operates the variable polarization elements 24a and 24b so that they do not rotate the polarization direction of the laser light. Furthermore, the measurement control unit 11 controls the MEMS driver 21 by sending a command to the deflection control unit 12 and controls the optical deflection angle of the MEMS mirror 22 to θxsc1, which is a quantity corresponding to the angle of incidence θ1. As a result, a field of view is formed using the optical path.

[0054] Furthermore, the measurement control unit 11 acquires vehicle speed information (step S12), and if the vehicle speed is equal to or greater than a first threshold value (e.g., 80 km / h) (step S13; JA), the measurement mode is switched to a high-speed mode, which is a measurement mode using the second optical path (step S14): Specifically, the measurement control unit 11 controls the driver 23 for the variable polarization element by sending a command to the polarization control unit 13 and operates the variable polarization elements 24a and 24b so that they rotate the polarization direction of the laser light by 90°. Furthermore, the measurement control unit 11 controls the MEMS driver 21 by sending a command to the deflection control unit 12 and controls the optical deflection angle of the MEMS mirror 22 to θxsc2, which is a quantity corresponding to the angle of incidence θ2.As a consequence, the field of view is formed using the second optical path. The process then returns to step S12.

[0055] If the vehicle speed is less than the first threshold (step S13; NO), and the vehicle speed is equal to or less than the second threshold, which is less than the first threshold (S15; YES), the measurement control unit 11 switches the measurement mode to the low-speed mode, which uses the second optical path (step S16). The procedure then returns to step S12. Conversely, if the vehicle speed is greater than the second threshold (step S15; NO), the procedure returns to step S12.

[0056] Here, the first threshold is a vehicle speed that serves as a reference for switching to high-speed mode, and it can be set to, for example, the 80 km / h described above. Furthermore, the second threshold is a vehicle speed that serves as a reference for switching to low-speed mode, and it can be set to, for example, the 60 km / h described above. The reason for setting two thresholds in this way is to prevent the measurement mode from switching more frequently than necessary.

[0057] According to the embodiment described above, it is possible to provide an optical scanning device capable of significantly changing the field of view during optical scanning, and furthermore an object detection device that incorporates this capability.

[0058] It should be noted here that the present disclosure is not limited to the content of the embodiment described above and can be modified in various ways and implemented within the scope of the present disclosure. For example, the embodiment above illustrates, as an example of the application for the object detection device, a case is shown where an object detection device is attached to a vehicle to detect objects around the vehicle, but the application is not limited thereto.

[0059] Furthermore, the optical configuration of the scanning light source unit 20 in the embodiment described above is only an example, and there are no special restrictions as long as the two optical paths can be set in a variable way by combining the respective variable polarization elements 24a, 24b and the beam splitters 40a, 40b and achieving the desired values ​​as the angles of incidence θ1 and θ2 with respect to the MEMS mirror 22.

[0060] Furthermore, the embodiment described above uses two light sources 26a and 26b, but three or more light sources can be used. As in the modified example shown in Fig. 9(A) and Fig. As shown in Figure 9(B), for example, an object detection device can be configured to further comprise a third optical system, which includes a light source 50 and a mirror 51, in addition to a first optical system, which includes a light source 26a, mirrors 41a, 43a, a (not shown) variable polarizing element 24a, and a (not shown) polarizing beam splitter 40a, and a second optical system, which includes a light source 26b, mirrors 41b, 43b, a (not shown) variable polarizing element 24b, and a (not shown) polarizing beam splitter 40b. In the object detection device of the illustrated modified example, the laser light emitted by the light source 50 is reflected by the mirror 51 and enters the MEMS mirror 22, where it is scanned or guided.In the third optical system, the variable polarizing element or polarizing beam splitter is not used, and the optical path is fixed. Thus, a field of view (FOV3) is formed in a region containing the vertical line c at the reference position of the MEMS mirror 22. Furthermore, a field of view is formed by the first optical system (FOV1) above the vertical line c in the figure, and a field of view is formed by the second optical system (FOV2) below the vertical line in the figure. In the illustrated embodiment, the fields of view FOV1, FOV2, and FOV3 are arranged in a fan shape that is symmetrical overall with respect to the vertical line c.

[0061] As in another modification example of the Fig. 10(A) and the Fig.As shown in Figure 10(B), either the first or the second optical system can be omitted. In the illustrated example, the first optical system described above is omitted, and the second and third optical systems are combined; however, the first and third optical systems can be combined instead.

[0062] The present disclosure has features as set out in the appendices below. (Appendix 1)

[0063] An optical scanning device used in a device which detects an object by emitting outgoing light and receiving reflected light, wherein the optical scanning device comprises the following: a deflector; at least one light source; a variable polarizing element arranged to receive light emitted by the light source and to emit either a first emission light consisting mainly of a first light in a first polarization state, or a second emission light consisting mainly of a second light in a second polarization state that differs from the first polarization state; a branching element that splits the first light and the second light in different directions; and an optical system that causes the first light, which has been branched or diverted by the branching element, to strike the deflector at a first angle and causes the second light, which has been branched or diverted by the branching element, to strike the deflector at a second angle that differs from the first angle. (Appendix 2)

[0064] The optical scanning device according to Appendix 1, where the light emitted by the light source is in the first polarization state, wherein the variable polarizing element transmits the light emitted by the light source without rotating the polarization direction of the light, thereby emitting the first light, and rotates the polarization direction of the light emitted by the light source by a predetermined angle, thereby emitting the second light. (Appendix 3)

[0065] The optical scanning device according to Appendix 2, where the polarization direction of the first light and the polarization direction of the second light differ by 90° from each other. (Appendix 4)

[0066] The optical scanning device according to Appendix 3, where the branching element is a polarization beam splitter. (Appendix 5)

[0067] The optical scanning device according to one of Appendices 1 to 4, which further comprises the following: a first driver that drives the light source, a second driver that drives the deflector, and a third driver that drives the variable polarization element. (Appendix 6)

[0068] An optical scanning device used in a device which detects an object by emitting an outgoing light and receiving a reflected light, wherein the optical scanning device comprises the following: a deflector; a first light source and a second light source; a first variable polarizing element arranged to receive light emitted by the first light source and emitting either a first emission light consisting mainly of a first light in a first polarization state, or a second emission light consisting mainly of a second light in a second polarization state that differs from the first polarization state; a first branching element which branches the first light and the second light in different directions; a first optical system which causes the first light, which has been branched or diverted by the branching element, to strike the deflector at a first angle and causes the second light, which has been branched or diverted by the branching element, to strike the deflector at a second angle which differs from the first angle; a second variable polarizing element, which is arranged to receive light emitted by the second light source, and either emits a third emission light consisting mainly of a third light in a first polarization state, or emits a third emission light consisting mainly of a fourth light in the second polarization state; a second branching element, which branches the third light and the fourth light in different directions; and a second optical system which causes the third light, which was branched or diverted from the second branching element, to strike the deflector at a third angle and causes the fourth light, which was branched or diverted from the branching element, to strike the deflector at a fourth angle which differs from the third angle. (Appendix 7)

[0069] The optical scanning device according to Appendix 6, which further comprises the following: a first driver that drives the first light source and the second light source, a second driver that drives the deflector, a third driver that drives the first variable polarization element and the second variable polarization element, wherein the first variable polarization element and the second variable polarization element are controlled by the third driver, selectively using a first field of view shaped by the first light and the third light, and a second field of view shaped by the second light and the fourth light. (Appendix 8)

[0070] The optical scanning device according to Appendix 7, where the first field of view is larger than the second field of view, wherein in the first field of vision a field of vision formed by the first light and a field of vision formed by the third light are continuously or throughout formed, and wherein in the second field of vision a field of vision formed by the second light and a field of vision formed by the fourth light are continuously or throughout formed. (Appendix 9)

[0071] An object detection device comprising the following: the optical scanning device according to one of Appendices 1 to 8; a light receiving unit which detects the detected light from the emitted light emitted by the optical scanning device and which generates a light receiving signal corresponding to the intensity of the reflected light; and a control unit configured to control the operation of the optical scanning device and to generate point group information based on the light reception signal. (Appendix 10)

[0072] The object detection device according to Appendix 9, wherein the device is attached to a vehicle, emits radiant light around the vehicle and generates the point group information based on the light reception signal according to the light reflected by the object around the vehicle. (Appendix 11)

[0073] The object detection device according to Appendix 10, wherein the control unit is configured to control the variable polarization element of the optical scanning device according to a vehicle speed of the vehicle so that it emits either the first light or the second light. (Appendix 12)

[0074] An object detection device comprising the following: the optical scanning device according to Appendix 8; a light receiving unit that detects the reflected light from the emitted light emitted by the optical scanning device and generates a light receiving signal according to the intensity of the reflected light; a control unit configured to control the operation of the optical scanning device and to generate point group information based on the light reception signal; wherein the optical scanning device is attached to a vehicle and emits the emitted light around the vehicle; wherein the light receiving unit detects the light reflected by the object around the vehicle and generates the light receiving signal; wherein the control unit is configured to generate point group information based on the light reception signal according to the light reception signal; and wherein the control unit is configured to control the optical scanning device so that it forms the first field of view at a first speed of the vehicle and forms the second field of view at a second speed which is greater than the first speed. REFERENCE MARK LIST 1 object detection device 10 Control unit 20 scanning light source unit (optical scanning device) 21 MEMS drivers 22 MEMS mirrors 23 drivers for the variable polarization element 24a, 24b variable polarization element 25 light source drivers 26a, 26b Light source 30 light receiving units 40a, 40b Polarization beam splitter 41a, 41b, 42a, 42b, 43a, 43b mirrors QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2010-151958 [0002, 0003]

Claims

[1] Optical scanning device used in a device which detects an object by emitting outgoing light and receiving reflected light, wherein the optical scanning device comprises: a deflector; at least one light source; a variable polarizing element arranged to receive light emitted by the light source and to emit either a first emission light consisting mainly of a first light in a first polarization state, or a second emission light consisting mainly of a second light in a second polarization state that differs from the first polarization state; a branching element that splits the first light and the second light in different directions; and an optical system that causes the first light, which has been branched or diverted by the branching element, to strike the deflector at a first angle and causes the second light, which has been branched or diverted by the branching element, to strike the deflector at a second angle that differs from the first angle. [2] Optical scanning device according to claim 1, where the light emitted by the light source is in the first polarization state, wherein the variable polarizing element transmits the light emitted by the light source without rotating the polarization direction of the light, thereby emitting the first light, and rotates the polarization direction of the light emitted by the light source by a predetermined angle, thereby emitting the second light. [3] Optical scanning device according to claim 2, wherein the polarization direction of the first light and the polarization direction of the second light differ from each other by 90°. [4] Optical scanning device according to claim 3, wherein the branching element is a polarization beam splitter. [5] Optical scanning device according to claim 1, which further comprises: a first driver that drives the light source, a second driver that drives the deflector, and a third driver that drives the variable polarization element. [6] Optical scanning device used in a device which detects an object by emitting an outgoing light and receiving a reflected light, wherein the optical scanning device comprises: a deflector; a first light source and a second light source; a first variable polarizing element arranged to receive light emitted by the first light source and emitting either a first emission light consisting mainly of a first light in a first polarization state, or a second emission light consisting mainly of a second light in a second polarization state that differs from the first polarization state; a first branching element which branches the first light and the second light in different directions; a first optical system which causes the first light, which has been branched or diverted by the branching element, to strike the deflector at a first angle and causes the second light, which has been branched or diverted by the branching element, to strike the deflector at a second angle which differs from the first angle; a second variable polarizing element, which is arranged to receive light emitted by the second light source, and either emits a third emission light consisting mainly of a third light in a first polarization state, or emits a third emission light consisting mainly of a fourth light in the second polarization state; a second branching element, which branches the third light and the fourth light in different directions; and a second optical system which causes the third light, which was branched or diverted from the second branching element, to strike the deflector at a third angle and causes the fourth light, which was branched or diverted from the branching element, to strike the deflector at a fourth angle which differs from the third angle. [7] Optical scanning device according to claim 6, further comprising: a first driver that drives the first light source and the second light source, a second driver that drives the deflector, a third driver that drives the first variable polarization element and the second variable polarization element, wherein the first variable polarization element and the second variable polarization element are controlled by the third driver, selectively using a first field of view shaped by the first light and the third light, and a second field of view shaped by the second light and the fourth light. [8] Optical scanning device according to claim 7, where the first field of view is larger than the second field of view, wherein in the first field of vision a field of vision formed by the first light and a field of vision formed by the third light are continuously or throughout formed, and wherein in the second field of vision a field of vision formed by the second light and a field of vision formed by the fourth light are continuously or throughout formed. [9] Object detection device comprising the following: the optical scanning device according to claim 1 or 6; a light receiving unit which detects the detected light from the emitted light emitted by the optical scanning device and which generates a light receiving signal corresponding to the intensity of the reflected light; and a control unit configured to control the operation of the optical scanning device and to generate point group information based on the light reception signal. [10] Object detection device according to claim 9, wherein the device is attached to a vehicle, emits radiant light around the vehicle and generates the point group information based on the light reception signal according to the light reflected by the object around the vehicle. [11] Object detection device according to claim 10, wherein the control unit is configured to control the variable polarization element of the optical scanning device according to a vehicle speed of the vehicle so that it emits either the first light or the second light. [12] Object detection device comprising the following: the optical scanning device according to claim 8; a light receiving unit that detects the reflected light from the emitted light emitted by the optical scanning device and generates a light receiving signal according to the intensity of the reflected light; a control unit configured to control the operation of the optical scanning device and to generate point group information based on the light reception signal; wherein the optical scanning device is attached to a vehicle and emits the emitted light around the vehicle; wherein the light receiving unit detects the light reflected by the object around the vehicle and generates the light receiving signal; wherein the control unit is configured to generate point group information based on the light reception signal according to the light reception signal; and wherein the control unit is configured to control the optical scanning device so that it forms the first field of view at a first speed of the vehicle and forms the second field of view at a second speed which is greater than the first speed.

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