Light projecting device and mobile body

Abstract

A light projecting device (100) includes: a first mirror (30) and a second mirror (40) that are opposed to each other and extend in a first direction; and a light waveguide layer (20) that is located between the first mirror and the second mirror, has a structure in which a refractive index and / or a thickness can be changed, and guides light in the first direction. The first mirror has a higher light transmittance than the second mirror, and emits at least a portion of the light that propagates in the light waveguide layer to the outside. By changing the refractive index and / or the thickness of the light waveguide layer, the emission angle of the light emitted from the first mirror can be changed in a range from an angle θ1 to an angle θ2 (> θ1). First light that is emitted at the emission angle θ1 is projected more downward than second light that is emitted at the emission angle θ2.

Description

Technical Field

[0001] This disclosure relates to a light-projection device and a mobile body. Background Technology

[0002] Previously, various devices have been proposed that use a projected beam to scan a scene and detect reflected light from objects contained in the scene to measure the distance to the objects (for example, see Patent Documents 1 and 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-128663

[0006] Patent Document 2: U.S. Patent Application Publication No. 2018 / 0224709 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The purpose of this disclosure is to provide a light projection device that can extend the detectable distance of distant objects and suppress the saturation of the detection signal of nearby objects.

[0009] Methods used to solve problems

[0010] A light-projecting device according to one of the technical solutions disclosed herein is a light-projecting device equipped with a light deflection device. The light deflection device has a light-emitting surface that emits light in a direction intersecting the light-emitting surface. It is capable of varying the emission angle of the light emitted from the light-emitting surface along the first direction in a range from the first angle to a second angle larger than the first angle. The light deflection device is configured such that the light spot with a larger width in the first direction at a distance is projected more vertically downward than the second light emitted from the light-emitting surface at the first angle and the light emitted from the light-emitting surface at the second angle.

[0011] Invention Effects

[0012] According to the technology disclosed herein, a light projection device is available that can extend the detectable distance of distant objects and suppress the saturation of detection signals for nearby objects. Attached Figure Description

[0013] Figure 1 This is a perspective view schematically showing an example of the structure of a projection device in an exemplary embodiment.

[0014] Figure 2 It is observed along the +Y direction. Figure 1 The diagram shown illustrates the structure.

[0015] Figure 3A It is a diagram schematically illustrating the situation of light emanating from a light-emitting surface when the propagation angle is relatively small.

[0016] Figure 3B It is a diagram schematically illustrating the situation of light emanating from the light-emitting surface when the propagation angle is relatively large.

[0017] Figure 4 This is a diagram illustrating an example of the relationship between the propagation length and the diffusion angle of the emitted light in the X direction.

[0018] Figure 5A This is a perspective view schematically illustrating an example of a light-projecting device according to an embodiment of the present disclosure.

[0019] Figure 5B This is a side view schematically illustrating an example of a light-projecting device according to an embodiment of the present disclosure.

[0020] Figure 6 This diagram illustrates the action of the projection device in this embodiment in detecting objects at close or distant distances.

[0021] Figure 7A This is a perspective view schematically showing an example of a projection device of the first modified embodiment of this invention.

[0022] Figure 7B It is observed along the -Y direction Figure 7A The diagram shown illustrates the structure.

[0023] Figure 8A This is a perspective view schematically showing an example of a projection device of the second modified embodiment of this invention.

[0024] Figure 8B It is observed along the -Y direction Figure 8A The diagram shown illustrates the structure.

[0025] Figure 9A This is a perspective view schematically showing an example of a projection device of the third modified embodiment of this invention.

[0026] Figure 9B It is observed along the -Y direction Figure 9A The diagram shown illustrates the structure.

[0027] Figure 10A This is a perspective view schematically showing an example of a projection device of the fourth variation of this embodiment.

[0028] Figure 10B It is observed along the +Y direction. Figure 10A The diagram shown illustrates the structure.

[0029] Figure 11AThis is a perspective view schematically showing an example of a projection device in the fifth variation of this embodiment.

[0030] Figure 11B It is observed along the +Y direction. Figure 11A The diagram shown illustrates the structure.

[0031] Figure 12 This is a perspective view schematically showing an example of a projection device of the sixth modified embodiment of this invention.

[0032] Figure 13A This is a perspective view schematically showing an example of a projection device in the seventh variation of this embodiment.

[0033] Figure 13B It is observed along the -Y direction Figure 13A The diagram shown illustrates the structure.

[0034] Figure 14A This is a perspective view schematically showing a first application example of mounting the projection device of this embodiment on a vehicle.

[0035] Figure 14B This is a side view schematically showing a first application example of mounting the projection device of this embodiment on a vehicle.

[0036] Figure 15 This is a perspective view schematically illustrating a second application example of mounting the projection device of this embodiment in a monitoring system. Detailed Implementation

[0037] Before describing the embodiments of this disclosure, the understanding that forms the basis of this disclosure will be explained.

[0038] Figure 1 This is a perspective view schematically showing an example of the structure of a projection device 100 according to an exemplary embodiment. Figure 2 It is observed along the +Y direction. Figure 1 The diagram shows the configuration. The mutually orthogonal X, Y, and Z axes are schematically represented for reference. In this specification, the direction in which the arrow points to the axis is designated as the "+" direction, and the opposite direction as the "-" direction. However, these designations are used merely for illustrative purposes and do not limit the actual orientation of the light deflection device 10 during use. Furthermore, the shape and size of the structure shown in the diagram, either as a whole or in part, do not limit the actual shape and size.

[0039] The light projection device 100 includes at least one light deflection device 10. The light deflection device 10 directs a light beam emitted from a light source (not shown) in a predetermined direction. The light deflection device 10 includes a first mirror 30, a second mirror 40, and an optical waveguide layer 20. The first mirror 30 and the second mirror 40 are opposite each other and extend in the X direction. The first mirror 30 is positioned closer to the second mirror 40 in the +Z direction. The transmittance of the first mirror 30 is higher than that of the second mirror 40. At least one of the first mirror 30 and the second mirror 40 may be formed, for example, of a multilayer reflective film consisting of alternating layers of multiple high-refractive-index layers and multiple low-refractive-index layers. The first mirror 30 and the second mirror 40 may be formed of a multilayer reflective film including the same high-refractive-index layers and the same low-refractive-index layers. In this case, if the number of layers in the first mirror 30 is less than the number of layers in the second mirror 40, the transmittance of the first mirror 30 is higher than that of the second mirror 40. The optical waveguide layer 20 is located between the first mirror 30 and the second mirror 40.

[0040] The first mirror 30 has a light-emitting surface 30es parallel to the XY plane on the side opposite to the optical waveguide layer 20. Light 22 propagates along the X direction within the optical waveguide layer 20, being reflected by the first mirror 30 and the second mirror 40. At this time, a portion of the light 22 is emitted outward from the light-emitting surface 30es as a beam 22b. The direction of the central axis of the beam 22b depends on the refractive index and / or thickness of the optical waveguide layer 20. In this specification, the direction of the central axis of the beam 22b is simply referred to as the "emission direction of the beam 22b".

[0041] The optical waveguide layer 20 may have a configuration in which the refractive index and / or thickness vary according to the applied driving voltage. Figure 2 In the example shown, the optical waveguide layer 20 contains a liquid crystal material, and two electrodes 10e for applying a driving voltage can be disposed on the reflective surfaces 30s and 40s of the optical waveguide layer 20. If the driving voltage changes due to an input of a control signal from a control device (not shown), the refractive index of the optical waveguide layer 20 changes, and the emission direction of the light beam 22b emitted from the light emission surface 30es changes along the X direction. In another example, the optical waveguide layer 20 contains a gas or liquid, and the first mirror 30 and / or the second mirror 40 can be mounted on an actuator that deforms when a driving voltage is applied. If the driving voltage changes due to an input of a control signal from a control device (not shown), the thickness of the optical waveguide layer 20 changes with the change in mirror spacing caused by the deformation of the actuator, and the emission direction of the light beam 22b emitted from the light emission surface 30es changes along the X direction. As described above, the light deflection device 10 can change the emission direction of the light beam 22b emitted from the light emission surface 30es along the X direction in response to an external control signal. Figure 1 The thick line parallel to the X direction indicates the scanning direction of beam 22b.

[0042] The emission angle θ of the light emitted from the light deflection device 10 into the air is represented by the following formula (1).

[0043] [Formula 1]

[0044]

[0045] Here, n w λ is the refractive index of the optical waveguide layer 20, λ is the wavelength of light in air, d is the thickness of the optical waveguide layer 20, and m is the order. According to equation (1), by changing λ and n... w One of the options, or d, can change the direction of light emission.

[0046] The light projection device 100 includes a control device (not shown) that causes changes in the refractive index and / or thickness of the optical waveguide layer 20.

[0047] The operating principle and method of the optical deflection device 10 are disclosed in detail in U.S. Patent Application Publication No. 2018 / 0224709. The entire disclosure of that document is referenced in this specification.

[0048] <Emission angle and diffusion angle of emitted light>

[0049] The diffusion angle of the light emitted from the light deflection device 10 determines the energy density of the beam spot illuminating the object. If the diffusion angle narrows, the energy density of the beam spot increases; if the diffusion angle widens, the energy density decreases. The relationship between the diffusion angle and the emission angle of the light emitted from the conventional light deflection device 10 will be explained below.

[0050] The far-field pattern of the light emitted from the light deflection device 10 is equivalent to Figure 2 The Fourier transform of the electric field distribution on the light emitting surface 30es is shown. Since the light 22 propagates inside the optical waveguide layer 20, the diffusion angle in the Y direction at the far end of the emitted light, when the optical deflection device 10 is present alone, mainly depends on the width of the optical waveguide layer 20.

[0051] On the other hand, the diffusion angle in the X direction at the far end of the emitted light depends primarily on the propagation length of light 22. That is, the longer the propagation length of light 22 in the optical waveguide layer 20, the narrower the diffusion angle in the X direction at the far end (i.e., the far field) of the emitted light. Conversely, the shorter the propagation length of light in the optical waveguide layer 20, the wider the diffusion angle in the X direction at the far end (i.e., the far field) of the emitted light. Here, the propagation length refers to the distance by which the intensity of light 22, which propagates while attenuating in the optical waveguide layer 20, decreases to a factor of 1 / e. e is the base of the natural logarithm. The diffusion angle refers to the angle Δθ that diffuses outwards from the emission angle θ. Specifically, the diffusion angle is denoted as the full width at half maximum (FWHM) of the emitted light in the angular spectrum.

[0052] Typically, when the propagation length is longer than the width of the optical waveguide layer 20, the light spot at a distance from the emitted light is close to a linear shape.

[0053] Figure 3A and Figure 3B These diagrams schematically illustrate the light emitted from the light-emitting surface 30es under relatively small and relatively large propagation angles φ. For simplicity, it is assumed that the reflectivity of the first mirror 30 and the second mirror 40 is constant regardless of the propagation angle φ. Figure 3A In the example shown, because the propagation angle φ is small, the number of times reflector surfaces 30s and 40s reflect light 22 per unit length is increased. Therefore, the propagation length L... p Shortened. Figure 3B In the example shown, because the propagation angle φ is large, the number of times reflector surfaces 30s and 40s reflect light 22 per unit length is reduced. Therefore, the propagation length L... p The propagation length increases. Since there is a positive correlation between the propagation angle φ and the emission angle θ, the larger the emission angle θ, the longer the propagation length L. p And it gets longer. Additionally, in Figure 3A and Figure 3B The propagation length L, represented by the double arrow, is... p The indicated length is not the actual length.

[0054] Figure 4 It represents the propagation length L. p A diagram illustrating an example of the relationship between the diffusion angle Δθ of the emitted light and the X-direction. Figure 4 The graph shown represents the linewidth of a light beam emitted from an optical deflector 10, with the propagation length varied in various ways, calculated based on conditions such as the dimensions and dielectric constant of its constituent components. For example... Figure 4 As shown, the propagation length L p The longer the propagation length L, the narrower the spread angle Δθ of the emitted light. As mentioned above, if the emission angle θ increases, the propagation length L... p As the emission angle θ increases, the diffusion angle Δθ of the emitted light decreases. Therefore, it can be concluded that if the emission angle θ changes, the diffusion angle Δθ of the emitted light will change.

[0055] The inventors of this disclosure have discovered that if this phenomenon is applied to a light-projecting device that scans in a direction perpendicular to the ground, it is possible to increase the detectable distance of distant objects with a relatively simple configuration and to suppress the saturation of the detection signal for nearby objects. The embodiments of this disclosure described below are based on this understanding.

[0056] The light-projecting device related to the first item is a light-projecting device equipped with a light deflection device. The light deflection device includes: a first mirror and a second mirror, facing each other and extending along a first direction; and an optical waveguide layer located between the first mirror and the second mirror, guiding light along the first direction, and having a structure capable of varying its refractive index and / or thickness. The first mirror has a higher light transmittance than the second mirror and has a light-emitting surface that emits at least a portion of the light propagating within the optical waveguide layer to the outside. By varying the refractive index and / or the thickness of the optical waveguide layer, the emission angle of the light emitted from the light-emitting surface of the first mirror can be varied in the range from angle θ1 to an angle θ2 larger than angle θ1. The light deflection device is configured such that the first light emitted from the light-emitting surface at an emission angle θ1 is projected more vertically downward than the second light emitted from the light-emitting surface at an emission angle θ2.

[0057] In this projection device, the detectable distance of distant objects can be increased, and the detection signal saturation of nearby objects can be suppressed.

[0058] The projection device for the second item further includes an optical element in the projection device for the first item, which is arranged in the optical path of the light emitted from the light-emitting surface of the first mirror, so that the direction of the light changes so that the first light is more vertically downward than the second light.

[0059] In this light projection device, the first light can be directed more vertically downwards than the second light through optical elements.

[0060] In the light-emitting device of the third item, the optical element refracts the light emitted from the light-emitting surface of the first mirror.

[0061] In this light projection device, the direction and / or diffusion angle of the light emitted from the light emission surface can be adjusted by the refraction of light.

[0062] In the light-emitting device of item 4, the optical element of item 3 includes one or more lenses that expand or reduce the diffusion angle of the light emitted from the light-emitting surface.

[0063] In this light projection device, by expanding the diffusion angle of the emitted light, the saturation of the detection signal of nearby objects can be further suppressed, and by reducing the diffusion angle of the emitted light, the detectable distance of distant objects can be further increased.

[0064] In the light-emitting device of item 5, which relates to the light-emitting device of item 2, the optical element reflects the light emitted from the light-emitting surface of the first mirror.

[0065] In this light projection device, the direction and / or diffusion angle of the light emitted from the light emission surface can be adjusted by the reflection of the light.

[0066] In the light-emitting device of item 6, the optical element of item 5 includes one or more mirrors that expand or reduce the diffusion angle of the light emitted from the light-emitting surface.

[0067] In this light projection device, by expanding the diffusion angle of the emitted light, the saturation of the detection signal of nearby objects can be further suppressed, and by reducing the diffusion angle of the emitted light, the detectable distance of distant objects can be further increased.

[0068] The light-emitting device for item 7, in any of items 1 to 6, further includes a control device for changing the refractive index and / or thickness of the aforementioned optical waveguide layer.

[0069] In this light projection device, the direction of light emitted from the light emission surface can be adjusted by changing the refractive index and / or thickness of the light waveguide layer through a control device.

[0070] The movable body related to item 8 is a movable body equipped with a light-emitting device according to any one of items 1 to 7. The light-emitting device emits light from the light-emitting surface of the first mirror toward the front of the movable body.

[0071] In this mobile device, information about nearby objects such as the ground and distant objects such as people can be accurately obtained. In this disclosure, all or part of a circuit, unit, device, component, or section, or all or part of a functional block in a block diagram, may be executed by one or more electronic circuits, including semiconductor devices, semiconductor integrated circuits (ICs), or LSIs (large scale integration). An LSI or IC can be integrated onto a single chip or constructed by combining multiple chips. For example, functional blocks other than storage elements may be integrated onto a single chip. Here it is referred to as an LSI or IC, but the terminology varies depending on the degree of integration; it may also be called a system LSI, VLSI (very large scale integration), or ULSI (ultra large scale integration). For the same purpose, a Field Programmable Gate Array (FPGA) that can be programmed after the LSI is manufactured, or a reconfigurable logic device capable of reconfiguring the internal bonding relationships or setting the internal circuit partitioning of the LSI, may also be used.

[0072] Furthermore, all or part of the functions or operations of a circuit, unit, device, component, or part can be executed through software processing. In this case, the software is recorded on one or more non-transitory recording media such as ROM, optical disk, hard disk, etc. When the software is executed by a processor, the functions determined by the software are executed by the processor and peripheral devices. The system or device may also include one or more non-transitory recording media containing the software, a processor, and necessary hardware devices, such as interfaces.

[0073] In this disclosure, "light" refers to electromagnetic waves that include not only visible light (wavelength from about 400 nm to about 700 nm), but also ultraviolet light (wavelength from about 10 nm to about 400 nm) and infrared light (wavelength from about 700 nm to about 1 mm).

[0074] The following describes more specific embodiments of this disclosure. However, there are instances where necessary detailed descriptions have been omitted. For example, detailed descriptions of already known matters and repetitive descriptions of substantially the same components have been omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the inventors of this disclosure have provided the drawings and the following description to enable those skilled in the art to fully understand this disclosure, but these are not intended to limit the subject matter of the claims. In the following description, the same or similar constituent elements are given the same reference numerals.

[0075] (Implementation Method)

[0076] First, refer to Figure 5A and Figure 5B This section describes a basic configuration example of an optical device according to an embodiment of the present disclosure. Figure 5A and Figure 5B These are perspective and side views, respectively, schematically illustrating an example of the light-emitting device 100 according to an embodiment of the present disclosure. In these views, in addition to the X, Y, and Z axes described above, mutually orthogonal U and V axes are also schematically shown. The U-axis represents the component parallel to the ground, and the V-axis represents the component perpendicular to the ground. The U-axis is parallel to the Y-axis. The light-emitting device 100 is located above the ground. The light beam 22b is microscopically emitted from a light-emitting surface 30es having an area in a plane parallel to the XY plane, but for simplicity, it is described as emitting from point 1.

[0077] The light projection device 100 of this embodiment includes at least one light deflection device 10. Regarding the light deflection device 10, see [reference needed]. Figure 1 and Figure 2As explained above, the aforementioned light source may include, for example, a semiconductor laser element. The wavelength of the light beam emitted from the light source can be selected according to the application. When the distance to an object is measured by infrared measurement, the wavelength of the light beam may be, for example, 700 nm or more and 2.5 μm or less. The wavelength of the light beam may also be a wavelength within the visible range, i.e., about 400 nm or more and about 700 nm or less. The wavelength of the light beam may also be 2.5 μm or more.

[0078] The optical deflection device 10 is configured such that its scanning direction includes a component of the V direction. Figure 5A and Figure 5B In the example shown, the light deflection device 10 is configured such that the X-axis is tilted relative to the V-axis. The X-axis is parallel to the direction in which light propagates within the light deflection device 10. Figure 5B As shown, the light deflection device 10 scans between an emission angle θ1 and an emission angle θ2 that is larger than θ1. The light deflection device 10 is configured such that light emitted at emission angle θ1 is projected more vertically downwards than light emitted at emission angle θ2. This means that, in Figure 5B In the configuration shown, light from the light source is incident on the ground from the lower end of the optical waveguide layer 20. Vertically downward corresponds to the -V direction.

[0079] The scanning range is, for example, from the emission angle θ1 = 5° to the emission angle θ2 = 35°, and the angle between the light emission surface 30es and the V-axis can be, for example, 35°. In this case, the light emitted at the emission angle θ1 is incident on the ground, while the light emitted at the emission angle θ2 propagates parallel to the ground.

[0080] If the light deflection device 10 is configured in such a way that the diffusion angle Δθ1 of the light emitted at the emission angle θ1 becomes larger than the diffusion angle Δθ2 of the light emitted at the emission angle θ2. That is, the light emitted at the emission angle θ1 forms a relatively coarse spot in the X direction. Since the V direction, which is perpendicular to the ground, contains a component of the X direction parallel to the scanning direction, the light emitted in the -V direction forms a relatively coarse spot.

[0081] Figure 6 This diagram illustrates the operation of the projection device 100 in this embodiment for detecting objects at close or distant distances. Figure 6In the example shown, the near-field object is the ground, and the far-field object is a person. The scanning direction of the light emitted from the projection device 100 of this embodiment is perpendicular to the ground. The scanning direction of the light is indicated by a thick double arrow. The light illuminating the ground or the portion close to the ground forms a relatively thick spot. When the projection device 100 of this embodiment illuminates a near-field object, the intensity of its reflected light increases compared to a far-field object. Conventionally, if the reflected light from a near-field object is detected by a photodetector or image sensor, the detection signal saturates, resulting in a problem where information such as distance and shape related to the near-field object cannot be accurately obtained.

[0082] However, according to the light projection device 100 of this embodiment, since the light spot is relatively coarse when scanning in the -V direction, the energy density of the light irradiating the nearby object can be reduced. As a result, the intensity of the reflected light is reduced, suppressing the saturation of the detection signal, and information about the nearby object can be obtained more accurately.

[0083] Conversely, when the light-projecting device 100 of this embodiment illuminates a distant object, the intensity of the reflected light is reduced compared to a nearby object. Conventionally, the signal-to-noise ratio (S / N) of the detection signal decreases the further away the object, leading to a problem where information about distant objects cannot be accurately obtained.

[0084] However, according to the light-emitting device 100 of this embodiment, when scanning in the +V direction, the light spot is relatively fine, so the energy density of the light irradiating a distant object can be increased. Therefore, the decrease in the S / N ratio of the detection signal is suppressed, and information about the distant object can be obtained.

[0085] Furthermore, distant objects typically appear small in the detection image, making it difficult to accurately obtain information about them. However, the illumination device 100 of this embodiment can reduce the size of the light spot when illuminating a distant object. This improves the detection resolution in the direction perpendicular to the ground, enabling more accurate acquisition of information about distant objects.

[0086] (Modified Example)

[0087] Next, refer to Figures 7A to 12 The following describes the first to sixth modifications of the light-projecting device 100 according to this embodiment. In these figures, the constituent elements are shown in a separate state for ease of understanding, but these constituent elements may also be in contact.

[0088] Figure 7A This is a perspective view schematically showing an example of the projection device 110 of the first modified embodiment of this invention. Figure 7B It is observed along the -Y direction Figure 7A The diagram shows the configuration. The difference between the first modified light-emitting device 110 and the light-emitting device 100 of this embodiment is that the optical element 50 is arranged in the optical path of the light emitted from the light-emitting surface 30es of the light deflection device 10. The optical element 50 is capable of refracting the light emitted from the light-emitting surface 30es of the light deflection device 10.

[0089] exist Figure 7B In the example shown, optical element 50 has a cylindrical concave lens with curvature in a predetermined direction that includes at least the X-direction component. In this concave lens, the curvature in the X-direction can be increased, at least within the range of light scanning. The radius of curvature of the concave lens can be, for example, greater than 1 mm and less than 100 mm. The diffusion angle in the X-direction of the light emitted from the light deflection device 10 at an emission angle θ1 is amplified by optical element 50 to become Δθ. 1A This allows for a further reduction in the energy density of light illuminating nearby objects. Consequently, the intensity of reflected light is reduced, suppressing saturation of the detection signal and enabling more accurate acquisition of information about nearby objects.

[0090] Figure 8A This is a perspective view schematically showing an example of the projection device 120 of the second modified embodiment of this invention. Figure 8B It is observed along the -Y direction Figure 8A The diagram shows the configuration. The difference between the projection device 120 of the second modification and the projection device 110 of the first modification is that the optical element 50 has a cylindrical convex lens, which has curvature in a predetermined direction that includes at least the X-direction component. In this convex lens, the curvature in the +X direction can be increased, at least within the range of light scanning. The radius of curvature of the convex lens can, for example, be more than 1 mm and less than 100 mm. The diffusion angle in the X direction of the light emitted from the light deflection device 10 at an emission angle θ2 is reduced by the optical element 50 to become Δθ. 2B This allows for an increase in the energy density of light illuminating distant objects. Consequently, it suppresses the decrease in the signal-to-noise ratio (S / N) of the detection signal, enabling the accurate acquisition of information about more distant objects.

[0091] Figure 9A This is a perspective view schematically showing an example of the projection device 130 of the third variation of this embodiment. Figure 9B It is observed along the -Y direction Figure 9AThe diagram shows the configuration. The difference between the projection device 130 of the third modification and the projection device 110 of the first modification is that the optical element 50 has a lens array comprising a plurality of concave lenses. The plurality of concave lenses are arranged along a predetermined direction that includes at least a component in the X direction. This lens array covers at least a portion of the range of light scanning. The curvature of each concave lens can also increase in the -X direction, at least within the range of light scanning. Therefore, similar to the first modification described above, information about nearby objects can be obtained more accurately.

[0092] The configuration of the light deflection device 10 in the first to third modifications is the same as in this embodiment. The light spot emitted from the light deflection device 10 becomes coarser when scanned in the -V direction and thinner when scanned in the +V direction. Using a concave lens with a smaller radius of curvature, a coarser light spot can be achieved for illuminating objects at close range. Using a convex lens with a smaller radius of curvature, a thinner light spot can be achieved for illuminating objects at a distance. The light projection device 110 in the first modification to the light projection device 130 in the third modification can be easily manufactured.

[0093] Furthermore, in the first to third modifications, the optical element 50 is arranged perpendicularly to the ground, but it may also be tilted. Additionally, the lens may be disposed not on the exit surface of the optical element 50 but on the incident surface, or it may be disposed on both the incident and exit surfaces.

[0094] Figure 10A This is a perspective view schematically showing an example of the projection device 140 of the fourth variation of this embodiment. Figure 10B It is observed along the +Y direction. Figure 10A The diagram shows the configuration. The difference between the fourth modification of the light-emitting device 140 and the first modification of the light-emitting device 110 is that the optical element 50 has a mirror. In this fourth modification, it is not necessary to precisely consider the light emission angle when configuring the light deflection device 10. That is, the degree of freedom in configuring the light deflection device 10 can be increased, and the fourth modification of the light-emitting device 140 can be manufactured more easily than the first modification of the light-emitting device 110 to the third modification of the light-emitting device 130. Furthermore, if the light deflection device 10 is configured with errors, the light can be projected in the desired direction by fine-tuning the configuration of the mirror provided with the optical element 50. For example, if the light deflection device 10 is configured by rotating it ψ° relative to the Y-axis from a predetermined position, the deviation in the light-emitting angle can be compensated by rotating the angle of the mirror (ψ / 2)° relative to the Y-axis.

[0095] Figure 11A This is a perspective view schematically showing an example of the projection device 150 of the fifth variation of this embodiment. Figure 11B It is observed along the +Y direction. Figure 11AThe diagram shows the configuration. The difference between the light-projecting device 150 of the fifth modification and the light-projecting device 140 of the fourth modification is that the optical element 50 has a cylindrical convex lens, which has curvature in a predetermined direction that includes at least the X-direction component. In this convex lens, the radius of curvature in the X-direction can be increased, at least within the range of light scanning. The radius of curvature of the convex lens can be, for example, more than 1 mm and less than 100 mm. The diffusion angle in the X-direction of the light emitted from the light deflection device 10 at an emission angle θ1 is amplified by the optical element 50 to become Δθ. 1D This not only increases the freedom of configuration of the optical deflection device 10, but also enables more accurate acquisition of information about objects at close range.

[0096] Figure 12 This is a perspective view schematically illustrating an example of the light-emitting device 160 of the sixth modification of this embodiment. The difference between the light-emitting device 160 of the sixth modification and the light-emitting device 100 of this embodiment is that a plurality of light deflection devices 10 are arranged along the Y direction. A plurality of phase shifters 60 are connected to each of the plurality of light deflection devices 10. The number of the plurality of light deflection devices 10 can be, for example, 8 or more and 64 or less. In the light-emitting device 160 of the sixth modification, a light beam is formed by the interference of light emitted from the plurality of light deflection devices 10. The light beam can also be said to be emitted outward from a larger light-emitting surface including a plurality of light-emitting surfaces 30es, but similar to the embodiments and modifications described above, in… Figure 12 For simplicity, it is recorded as originating from point 1. Figure 12 In the example shown, the width of the beam in the Y direction can be narrower compared to the example above. This is because the dimension in the Y direction of the larger light emitting surface mentioned above is larger than the dimension in the Y direction of the light emitting surface 30es in the example above.

[0097] The phase shifter 60 may have a configuration where the refractive index changes according to the applied driving voltage. In one example, the phase shifter 60 may be formed of a thermo-optical material whose refractive index changes with temperature. The phase shifter 60 includes a heater (not shown) for changing the temperature of the thermo-optical material. Two electrodes for applying the driving voltage are provided in the heater (not shown). As another example, the phase shifter 60 may be formed of an electro-optical material whose refractive index changes with the driving voltage. Two electrodes for applying the driving voltage to the electro-optical material are provided in the phase shifter 60. If the driving voltage changes due to an input control signal from a control device (not shown), the refractive index of the phase shifter 60 changes, thereby changing the phase of the light passing through the phase shifter 60. In the sixth modified light-emitting device 160, in response to the control signal, the driving voltage changes, and the phase of the light incident from the multiple phase shifters 60 to the multiple light deflection devices 10 changes by a certain amount in the order in which the multiple light deflection devices 10 are arranged. This phase shift allows the emission direction of the light beam to change along the Y direction. This enables two-dimensional scanning of light across the UV plane.

[0098] Figure 13A This is a perspective view schematically showing an example of the light-emitting device 170 of the seventh modification of this embodiment. The difference between the light-emitting device 170 of the seventh modification and the light-emitting device 100 of this embodiment is that the light deflection device 11 is composed of a plurality of optical waveguides 12 arranged along the X direction and a plurality of phase shifters 60 respectively connected to the plurality of optical waveguides 12. Each of the plurality of optical waveguides 12 has an optical waveguide region 12w for guiding light and a light emission region 12r for emitting light. Furthermore, each of the plurality of light emission regions 12r is provided with a grating 12g. With this configuration, light emitted from the light emission surface 30es can be scanned along the V direction. The light emission region 12r can also replace the grating 12g and, like the light deflection device 10 of the above embodiment, be composed of two mirrors and an optical waveguide layer present between them. With this configuration, light can be scanned along the U direction in addition to the V direction.

[0099] Light propagating along the Y direction in the optical waveguide region 12w originates from diffraction based on the grating 12g and is emitted outward from the light emission region 12r as multiple diffracted beams parallel to the YZ plane. The length of the light emission region 12r in the Y direction can be, for example, more than 1 μm and less than 10 μm. The number of recesses in the grating 12g can be, for example, more than 4 and less than 16. The length of the recess in the Y direction, i.e., the duty cycle, of each period of the recess in the grating 12g can also be appropriately changed according to the depth and number of the recesses in the grating. In the light deflection device 11 of the seventh modification, a beam is formed by the interference of light emitted from multiple optical waveguides 12. The beam can also be said to be emitted outward from the light emission surface 30es including multiple gratings 12g, but as in the above-described embodiments and modifications, in Figure 13A For the sake of simplicity, it is recorded as shooting from point 1.

[0100] Similar to the sixth modification, the phase shifter 60 can have a configuration where its refractive index changes according to the applied driving voltage. If the driving voltage changes via an input control signal from a control device (not shown), the refractive index of the phase shifter 60 changes, thereby changing the phase of the light passing through the phase shifter 60. In the light-emitting device 170 of the seventh modification, in response to the control signal, the driving voltage changes, and the phase of the light incident from the plurality of phase shifters 60 onto the plurality of optical waveguides 12 changes by a certain amount in the order in which the plurality of optical waveguides 12 are arranged. This phase shift allows the emission direction of the light beam to change along the V direction.

[0101] The width of the light spot in the V direction in the seventh variation depends on the width of the light beam 22b on the emitting portion of the light emitting region 12r. Figure 13B This is a diagram showing, on a microscopic scale (i.e., in the form of beams of light with width emitted from multiple optical waveguides, not as a single point), the relationship between the beams 22b emitted and their emission angles. Figure 13B The left diagram shows the case where the emission angle is θ1, and the right diagram shows the case where the emission angle is larger than θ1, θ2. Here, we assume that the emission angle perpendicular to the light emission surface 30es is zero degrees. Figure 13B As shown, the width of the beam 22b of the emitting portion, when viewed from the emission direction, depends on the emission angle θ. If the width of the light emission region is d, then the width of the beam 22b of the emitting portion is represented by dcosθ. In other words, the larger the emission angle, the smaller the width of the beam in the X direction when viewed from the emission direction. Therefore, the larger the emission angle, the larger the width of the light spot in the V direction at a distance (i.e., the far field).

[0102] In the light projection device 170, multiple phase shifters 60 change the phase of the light, thereby allowing the emission angle of the light emitted from the light emission surface 30es to vary within a range from angle θ1 to angle θ2, which is larger than angle θ1. Furthermore, the device is configured such that the first light emitted from the light emission surface 30es at emission angle θ1 is projected more vertically downwards than the second light emitted from the light emission surface 30es at emission angle θ2. Thus, similar to the embodiment described above, the intensity of the reflected light is reduced, suppressing saturation of the detection signal and enabling more accurate acquisition of information about nearby objects.

[0103] In the first to seventh modifications described above, it can be said that the optical element 50 changes the direction of light so that the light emitted from the light-emitting surface 30es at an emission angle θ1 is more vertically downward than the light emitted at an emission angle θ2. The optical element 50 is capable of causing light incident on the optical element 50 to exit at an angle different from the angle at which it is incident on the optical element 50.

[0104] In addition to the examples described above, in the second variation of the light-projecting device 120, the optical element 50 may also have a lens array comprising multiple convex lenses. The multiple convex lenses may also be arranged along a predetermined direction that includes at least a component of the X direction. In this case, the energy density of the light irradiated onto a distant object can be increased. Therefore, the decrease in the signal-to-noise ratio (S / N) of the detection signal can be suppressed, and information about the distant object can be obtained more accurately.

[0105] Furthermore, in the fifth modified light-projection device 150, the convex mirror for light emitted at angle θ1 can be replaced with a concave mirror for light emitted at angle θ2. Alternatively, in addition to the convex mirror for light emitted at angle θ1, a concave mirror for light emitted at angle θ2 can also be provided. In these cases, information about distant objects can be obtained more accurately. The optical element 50 may also include a plurality of mirrors arranged along a predetermined direction that includes at least the X-direction.

[0106] (Application Example)

[0107] Next, refer to Figures 14A to 15 The first and second application examples of the light-projecting device 100 of this embodiment will be explained.

[0108] Figure 14A and Figure 14B These are, respectively, a perspective view and a side view schematically illustrating a first application example in which the projection device 100 of this embodiment is mounted in a vehicle 100V. Figure 14A In the example shown, the vehicle 100V has a projection device 100 on its front surface. The projection device 100 emits light forward. Thus, the projection device 100 can be mounted on a moving body. Besides the vehicle 100V, the moving body could also be, for example, a ship or a tram. Figure 14B In the example shown, vehicle 100V is able to accurately obtain information about the ground at close range and people at a distance. The driver of vehicle 100V can then use this information to accurately assess the surrounding situation and drive safely.

[0109] Figure 15 This is a perspective view schematically illustrating a second application example of mounting the projection device 100 of this embodiment in a monitoring system 100S. Figure 15 In the example shown, the surveillance system 100S has a cylindrical shape. The surveillance system 100S has a projection device 100 on its side. The shape of the surveillance system 100S is arbitrary. The surveillance system 100S can, for example, be installed in or around a building. People inside the building can use information about nearby and distant objects obtained from the surveillance system 100S to ascertain the presence or absence of suspicious persons or objects around the building.

[0110] Industrial availability

[0111] The projection device disclosed herein can be used in applications such as LiDAR systems mounted on mobile vehicles, AGVs (Automated Guided Vehicles), ships, trams, and flying vehicles such as UAVs (Unmanned Aerial Vehicles). Furthermore, it can also be applied to surveillance systems installed in buildings.

[0112] Label Explanation

[0113] 10. Optical deflection device

[0114] 10e electrode

[0115] 20 Optical waveguide layers

[0116] 22 Light

[0117] 22 b beam

[0118] 30 First Frame

[0119] 30es light emission surface

[0120] 30s, 40s Reflecting surface

[0121] 40 Second Mirror

[0122] 50 Optical Components

[0123] 60 Phase Shifter

[0124] 100, 110, 120, 130, 140, 150, 160, 170 light projection device

[0125] 100V vehicles

[0126] 100S Monitoring System

Claims

1. A light projecting device provided with a light deflecting device, wherein the light deflecting device is provided with: a first mirror and a second mirror which oppose each other and extend in a first direction; and a light waveguide layer which is located between the first mirror and the second mirror, guides light in the first direction, and has a structure in which a refractive index and / or a thickness can be changed; the first mirror has a higher light transmittance than the second mirror, and has a light exit surface which emits at least a part of the light propagating in the light waveguide layer to the outside; by changing the refractive index and / or the thickness of the light waveguide layer, an exit angle of the light emitted from the light exit surface of the first mirror can be changed in a range from an angle θ1 to an angle θ2 which is larger than the angle θ1; the light deflecting device is configured so that a first light emitted at the exit angle θ1 from the light exit surface is projected more toward the vertical lower side than a second light emitted at the exit angle θ2 from the light exit surface, a first diffusion angle in the vertical direction of the first light is larger than a second diffusion angle in the vertical direction of the second light.

2. The light projecting device according to claim 1, wherein an optical element is further provided which is arranged on an optical path of the light emitted from the light exit surface of the first mirror, changes a direction of the light, and makes the first light be projected more toward the vertical lower side than the second light.

3. The light projecting device according to claim 2, wherein the optical element refracts the light emitted from the light exit surface of the first mirror.

4. The light projecting device according to claim 3, wherein the optical element includes one or more lenses which expand or contract a diffusion angle of the light emitted from the light exit surface.

5. The light projecting device according to claim 2, wherein the optical element reflects the light emitted from the light exit surface of the first mirror.

6. The light projecting device according to claim 5, wherein the optical element includes one or more mirrors which expand or contract a diffusion angle of the light emitted from the light exit surface.

7. The light projecting device according to any one of claims 1 to 6, wherein a control device which changes the refractive index and / or the thickness of the light waveguide layer is further provided.

8. A moving body provided with the light projecting device according to any one of claims 1 to 7, wherein the light projecting device emits the light from the light exit surface of the first mirror toward a front of the moving body.

9. A light projecting device provided with a light deflecting device, wherein the light deflecting device is provided with a light exit surface which emits light toward a direction intersecting the light exit surface, and can change an exit angle of the light emitted from the light exit surface in the first direction in a range from a first angle to a second angle which is larger than the first angle; the light deflecting device is configured so that, of a first light emitted at the first angle from the light exit surface and a second light emitted at the second angle from the light exit surface, the one having a larger width in the first direction in the vertical direction is projected more toward the vertical lower side than the other; a first diffusion angle in the vertical direction of the first light is larger than a second diffusion angle in the vertical direction of the second light.

10. A light projecting apparatus provided with a light deflection apparatus, wherein the light deflection apparatus is provided with: a plurality of optical waveguides arranged along a first direction and each extending in a second direction; and a plurality of phase shifters connected to the plurality of optical waveguides, respectively; the light deflection apparatus is capable of changing an emission angle along the first direction of light emitted from a light emission surface parallel to the first direction and the second direction in a range from an angle θ1 to an angle θ2 larger than the angle θ1; the light deflection apparatus is configured such that first light emitted at the emission angle θ2 from the light emission surface is projected more toward the vertical lower side than second light emitted at the emission angle θ1 from the light emission surface, a first diffusion angle in the vertical direction of the first light is larger than a second diffusion angle in the vertical direction of the second light.

Images