WO2021125018A1

WO2021125018A1 - Light emitting device, object detecting device, and mobile body

Info

Publication number: WO2021125018A1
Application number: PCT/JP2020/045885
Authority: WO
Inventors: Kento Nakamura; Tadashi Nakamura; Jun Kishiwada; Issei Abe
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2019-12-16
Filing date: 2020-12-09
Publication date: 2021-06-24
Anticipated expiration: 2022-06-16
Also published as: JP2021096225A

Abstract

In a light emitting device configured to emit scanning light to irradiate a target area, the light emitting device includes a light emitter configured to emit light; and a scanner including a deflecting surface configured to deflect the light as a result of being turned around a turning axis, to generate the scanning light. The light emitter is on a target area side of the deflecting surface, and the light emitter is further configured to emit the light to the deflecting surface in such a manner that a central axis of the light intersects a plane perpendicular to the turning axis.

Description

LIGHT EMITTING DEVICE, OBJECT DETECTING DEVICE, AND MOBILE BODY

The present application relates to a light emitting device, an object detecting device, and a mobile body.

An object detecting device such as a light detection and ranging or laser imaging detection and ranging (LIDAR) device, which is provided in a mobile body such as a vehicle, is known, includes a light emitting device which irradiates a target area such as an area on the front of the mobile body, and detects presence or absence of an object or the distance to an object by receiving light reflected or scattered by the object in the target area.

Further, a light emitting device, used in an object detecting device or the like, having a turning stage turnably supporting a light source and a scanner for deflecting the light emitted from the light source is disclosed. In the light emitting device, the deflected scanning light is emitted by the scanner while the turning stage turns to widen an area scanned by the scanning light (see, for example, PTL 1).

However, the device disclosed in PTL 1 has a size increased due to having the turning stage.

An object of the present invention is to emit scanning light at a wide angle while preventing a device from becoming larger in size.

A light emitting device according to an aspect of the present invention is configured to emit scanning light to irradiate a target area, and includes a light emitter configured to emit light; and a scanner including a deflecting surface configured to deflect the light as a result of being turned around a turning axis, to generate the scanning light. The light emitter is on a target area side of the deflecting surface. The light emitter is further configured to emit the light to the deflecting surface in such a manner that a central axis of the light intersects a plane perpendicular to the turning axis.

Effects of Invention

According to the present invention, scanning light can be emitted at a wide angle while preventing the size of a device from becoming larger.

Fig. 1 is a diagram partially illustrating a structure of a light emitting device according to a first embodiment. Fig. 2 is a view illustrating an example of a spread of scanning light with respect to a direction along a turning axis. Fig. 3 is a diagram illustrating an example of a spread of scanning light with respect to a direction perpendicular to the turning axis. Fig. 4 is a diagram illustrating an example of a structure of an object detecting device according to a second embodiment. Fig. 5 is a block diagram illustrating an example of a hardware configuration of the object detecting device according to the second embodiment. Fig. 6 is a block diagram illustrating a functional configuration of the object detecting device according to the second embodiment. Fig. 7 is a diagram illustrating an example of a noise light reducing condition. Fig. 8 is a diagram illustrating a configuration example of a light receiving lens including an eccentric free-form surface. Fig. 9 is a diagram partially illustrating an example of a configuration of an object detecting device according to a third embodiment. Fig. 10 is a diagram illustrating a configuration example of a scanning mirror of the object detecting device according to the third embodiment. Fig. 11 is a block diagram illustrating an example of a functional configuration of an object detecting device according to a fourth embodiment. Fig. 12 is a diagram illustrating a configuration example of a mobile body provided with an object detecting device according to a fifth embodiment. Fig. 13 is a block diagram illustrating an example of a hardware configuration of a mobile body according to a sixth embodiment. Fig. 14 is a diagram partially illustrating another first example of a configuration of an object detecting device according to an embodiment. Fig. 15 is a diagram illustrating another example of a noise light reducing condition. Fig. 16 is a diagram partially illustrating another second example of a configuration of an object detecting device according to an embodiment. Fig. 17 is a diagram partially illustrating another third example of a configuration of an object detecting device according to an embodiment. Fig. 18 is a view of a spread angle of light with respect to an Y direction in a first variant of a light emitting device. Fig. 19 is a view of a spread angle of light with respect to a X direction in a second variant of a light emitting device. Fig. 20 is a view of a spread angle of light with respect to a Y direction in a third variant of a light emitting device. Fig. 21 is a diagram partially illustrating another fourth example of a configuration of an object detecting device according to an embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In each of the drawings, the elements having the same structures may be given the same reference signs and duplicate descriptions may be omitted.

A light emitting device according to an embodiment emits light deflected by a scanner to irradiate a target area.

In this regard, when a part or all of a light emitter including a light source is included in a scanning space that is a three-dimensional space through which scanning light passes, mechanical vignetting occurs as a result of passing of the scanning light being partially obstructed by the light emitter, and it may be impossible to emit the scanning light at a wide angle (a wide area).

If the light emitter is provided at a position far from a deflecting surface of the scanner or the light emitter is provided on a side opposite to the target area side of the deflecting surface so as to prevent the light emitter from blocking the path of the scanning light to prevent mechanical vignetting from occurring and to enable the scanning light to scan at a wide angle, the light emitting device may become larger.

In this regard, according to an embodiment of the present invention, a light emitter emitting light and a scanner turning a deflecting surface around a turning axis to deflect the light emitted by the light emitter, to generate scanning light are provided. The light emitter is provided on the target area side, and emits light to irradiate the deflecting surface in such a manner that the central axis of the light intersects a plane perpendicular to the turning axis.

Thus, because the light emitter can be provided outside the scanning space, it is possible to avoid mechanical vignetting otherwise occurring due to the light emitter, and also, the light emitter can be provided closer to the scanner on the target area side of the scanner. As a result, the scanning light can be emitted at a wide angle while the size of the light emitting device can be prevented from becoming larger.

In another embodiment, a light emitter emitting light, and a scanner turning a deflecting surface around a turning axis to deflect the light emitted from the light emitter, to generate scanning light are provided. The light emitter includes a light source and an adjuster adjusting a spread angle of the light emitted from the light source, to generate the light emitted from the light emitter. The adjuster adjusts a spread angle of the light emitted from the light emitter with respect to a direction along the turning axis to be greater than a spread angle of the light from the light emitter with respect to a direction perpendicular to the turning axis.

Thus, the light emitter can be reduced in size with respect to the scanning direction of the scanning light, and the spread angle of the scanning light can be reduced with respect to the scanning direction of the scanning light. Thus, mechanical vignetting with respect to the scanning light otherwise caused by the light emitter can be prevented. Accordingly, the scanning light can be emitted at a wide angle while the size of the light emitting device can be prevented from becoming greater.

Hereinafter, embodiments will be described. In each embodiment, a light emitting device 100, an object detecting device 200, and a mobile body 1 are used as examples. In the descriptions of the embodiments, in a XYZ three-dimensional orthogonal coordinate system, a direction perpendicular to a turning axis of a deflecting surface of a scanner is referred to as an X direction, the direction along the turning axis of the deflecting surface of the scanner is referred to as a Y direction, and the direction intersecting both the X direction and the Y direction is referred to as a Z direction.

First Embodiment

Fig. 1 is a diagram partially illustrating an example of a light emitting device 100 according to the present embodiment. The light emitting device 100 generates scanning light 111 and emits the scanning light 111 to irradiate a target area 500. The target area 500 is a three-dimensional spatial area to be irradiated with the scanning light 111.

As illustrated in Fig. 1, the light emitting device 100 includes a light emitter 101 and a MEMS mirror 102. The light emitter 101 includes a semiconductor laser (i.e., laser diode (LD)) 1011 and a light guide lens 1012.

Laser light (emitted light), as emitted light 112, emitted by the semiconductor laser 1011 is transformed by the light guide lens 1012 into laser light having a predetermined spread angle, then irradiates the MEMS mirror 102, and is reflected by a deflecting surface 1020 of the MEMS mirror 102. Deflecting by deflecting surface 1020 means changing the propagation direction of the laser light, and reflecting is an example of deflecting. The emitted light 112 is an example of "light emitted from a light emitter".

The MEMS mirror 102 is such that the deflecting surface 1020 is turned around the turning axis 110 extending along the Y-axis, and the angle of the deflecting surface 1020 is changed through the turning, whereby the emitted light 112 is deflected with respect to the X direction around one axis and the scanning light 111 is generated. The MEMS mirror 102 is such that the deflecting surface 1020 can be turned in both the direction indicated by the arrow in Fig. 1 and the direction reverse to the direction indicated by the arrow in Fig. 1 (i.e., oscillation) around the turning axis 110. However, the MEMS mirror 102 may be such that the deflecting surface 1020 turns in one direction.

Any one of scanning light 1111 through scanning light 1114 (indicated as the central axes 1111c through 1114c of the scanning light in Fig. 1) included in the scanning light 111 of Fig. 1 is scanning light at any turned angle of the deflecting surface 1020 of the MEMS mirror 102. The turned angle is an angle that is changed through turning. At the reflected position P, the emitted light 112 is incident on and is reflected by the MEMS mirror 102.

It should be noted that the laser light irradiating the MEMS mirror 102 is any one of divergent light, convergent light, and parallel light whose spread angle is adjusted by the light guide lens 1012. For simplicity, Fig. 1 illustrates only the central axis 112c of the emitted light 112 of any one of divergent light, convergent light, and parallel light.

Similarly, the scanning light 111 from the MEMS mirror 102 is also one of divergent light, convergent light, and parallel light whose spread angle is adjusted. For simplicity, only the central axis 111c of the scanning light 111 is illustrated in Fig. 1.

The semiconductor laser 1011 is an example of a light source. However, the light source is not limited to the semiconductor laser 1011, and may be, for example, a vertical cavity surface emitting laser (VCSEL) or a light emitting diode (LED).

The wavelength of laser light emitted from the semiconductor laser 1011 is not particularly limited. However, in a case where the object detecting device 200 including the light emitting device 100 is provided in a vehicle, non-visible light, which is not visible to the naked eye and is not visible to a person, such as light having a wavelength longer than 760 nm, is desirable.

The light guide lens 1012 is an example of an adjuster and is a lens that adjusts the spread angle of laser light emitted by the semiconductor laser 1011 and directs the laser light after the spread angle adjustment to the MEMS mirror 102. The light guide lens 1012 may also have a beam transforming function such as a function of shaping the beam shape of laser light emitted by the semiconductor laser 1011 from an elliptical shape to a circular shape and collimating divergent laser light.

The adjuster is not limited to a lens such as the light guide lens 1012. The adjuster may be a reflective mirror or a prism that deflects laser light, or a combination of optical elements such as a lens, a reflective mirror, and a prism. In addition, a diffuser plate may be used as the adjuster to adjust the spread angle of laser light through diffusion. Thus, the adjuster may have a function of a light irradiating optical system that irradiates the MEMS mirror 102 with light emitted from the semiconductor laser 1011.

The MEMS mirror 102 is an example of a scanner and is a device manufactured through micromachining of silicon or glass using a micromachining technology that is applied technology of a semiconductor manufacturing technology.

The MEMS mirror 102 includes a moving section provided with the deflecting surface 1020 and a drive beam connected to the moving section and including a thin film piezoelectric material and a resilient beam on which the thin film piezoelectric material is laminated. The MEMS mirror 102 deflects emitted light 112 by turning the deflecting surface 1020 in response to an applied voltage. In Fig. 1, only the deflecting surface 1020 of the MEMS mirror 102 is illustrated for simplicity. The same manner applies to the following figures illustrating the MEMS mirror 102.

Because the known art disclosed in Japanese　Unexamined Patent Application Publication No. 2018-180565 can be applied to such a MEMS mirror 102, further details will be omitted.

The scanner is not limited to the MEMS mirror 102, and any device of turning a deflecting surface around a turning axis may be used instead, such as a galvano-mirror or a polygon mirror. The MEMS mirror 102 may be driven not only by a piezoelectric method but also by another drive method, such as an electrostatic method.

In the present embodiment, the three-dimensional space through which the scanning light 111 from the MEMS mirror 102 passes is referred to as a scanning space. A plane 113 indicated by a dashed line in Fig. 1 represents a plane perpendicular to the turning axis 110.

As illustrated in Fig. 1, in the present embodiment, the light emitter 101 is provided on the target area 500 side of the deflecting surface 1020 and emits light in such a manner that the central axis 112c of the emitted light 112 intersects the plane 113 perpendicular to the turning axis 110. The angle η in Fig. 1 is an angle at which the central axis 112c of the emitted light 112 intersects the plane 113. The MEMS mirror 102 is such that the deflecting surface 1020 is turned around the turning axis 110 to deflect the emitted light 112 emitted from the light emitter 101, to generate the scanning light 111.

Thus, the light emitter 101 is provided outside the scanning space, and thus, neither all nor a part of the light emitter 101 blocks the scanning light 111. Further, because the light emitter 101 does not block the scanning light 111, the light emitter 101 can be provided closer to the deflecting surface 1020 on the target area 500 side of the deflecting surface 1020.
<Spread angle of scanning light 111>

Next, the spread angle of the scanning light 111 emitted by the light emitting device 100 will be described with reference to Figs. 2 and 3. Fig. 2 is a diagram illustrating the spread angle of the scanning light 111 with respect to the Y direction, and Fig. 3 is a diagram illustrating the spread angle of the scanning light 111 with respect to the X direction.

As illustrated in Fig. 2, laser light emitted from the semiconductor laser 1011 is incident on the light guide lens 1012 while spreading with respect to the Y direction. The light guide lens 1012 transforms the incident divergent light into convergent light that converges with respect to the Y direction and guides the light to irradiate the deflecting surface 1020 of the MEMS mirror 102.

A beam 112y indicated by dashed lines represents a beam with respect to the Y direction of the emitted light 112 once converged with respect to the Y direction by the light guide lens 1012 and subsequently spreading. The spread angle θy is a spread angle with respect to the Y direction of the scanning light 111 incident on the deflecting surface 1020 of the MEMS mirror 102 and then reflected and deflected by the deflecting surface 1020 of the MEMS mirror 102 for scanning. The spread angle θy is previously determined.

The scanning light 111 reflected by the deflecting surface 1020 of the MEMS mirror 102 to deflect irradiates the target area 500 while spreading with the spread angle θy.

As illustrated in Fig. 3, the laser light emitted from the semiconductor laser 1011 is incident on the light guide lens 1012 while spreading with respect to the X direction. The light guide lens 1012 transforms the incident divergent light into divergent light with a smaller spread angle and directs the light to irradiate the MEMS mirror 102.

The beam 112x indicated by dashed lines represents a beam of the emitted light 112 diverging with respect to the X direction with a smaller spread angle. The spread angle θx is a spread angle with respect to the X direction of the scanning light 111 incident on the deflecting surface 1020 of the MEMS mirror 102 and subsequently reflected and deflected by the deflecting surface 1020 of the MEMS mirror 102. The spread angle θx is also previously determined.

The scanning light 111 is reflected by the deflecting surface 1020 of the MEMS mirror 102 and irradiates the target area 500 while spreading with the spread angle θx.

As illustrated in Figs. 2 and 3, the spread angle θy of the scanning light 111 with respect to the Y direction is greater than the spread angle θx with respect to the X direction. As a result, the beam shape 111s of the scanning light 111 is an ellipse having a major axis along the Y direction.

As described above, the scanning light 111, which has an elliptical beam shape having the major axis along the Y direction, is deflected with respect to the X direction by the MEMS mirror 102. In the present embodiment, the size of the target area 500 along the Y direction is determined by the spread angle θy, and the size of the target area 500 along the X direction is determined by the maximum scan angle Sx of the MEMS mirror 102.

In addition, it is desirable to increase the size of the deflecting surface 1020 of the MEMS mirror 102 along the Y direction, to provide a so large area of the deflecting surface 1020 that the emitted light 112 having the greater spread angle θy can be deflected by the deflecting surface 1020, and thus, provide a sufficient light amount of the scanning light 111.
<Effect of light emitting device 100>

An object detecting device, such as a LIDAR device, is known to be provided in a light emitting device provided in a mobile body, such as a vehicle. The light emitting device irradiates a target area, such as an area in front of the mobile body, and determines presence or absence of an object and the distance to the object by receiving light reflected or scattered by the object in the target area.

In a light emitting device used in such an object detecting device or the like, when part or all of a light emitter including a light source or the like is provided in a scanning space, the light emitter blocks the scanning light, so that a mechanical vignetting occurs and it is impossible to emit the scanning light at a wide angle.

If the light emitter is provided at such a position not to block the scanning light, or the light emitter is provided on the side opposite to the target area of a scanner in order to prevent mechanical vignetting and emit the light at a wide angle, the light emitting device may become greater in size.

Further, there is also disclosed a light emitting device to be provided in an object detecting device, where a turning stage supports a light source and a scanner in a turnable manner, scanning light is emitted by the scanner while the turning stage is being turned, so that scanning light can be emitted at a wide angle. However, because of the use of the turning stage in the light emitting device, the device may become greater and the device weight may be increased.

In the present embodiment, the light emitter 101 and the MEMS mirror 102 where the deflecting surface 1020 is turned around the turning axis 110 to deflect the emitted light 112 from the light emitter 101, to generate scanning light 111 are provided. Then, the light emitter 101 is provided on the target area 500 side of the deflecting surface 1020, and the light emitter 101 irradiates the deflecting surface 1020 with the emitted light in such a manner that the central axis of the emitted light 112 intersects the plane 113 perpendicular to the turning axis 110.

Thus, because the light emitter 101 can be provided outside the scanning space, it is possible to prevent mechanical vignetting with respect to the scanning light otherwise caused by the light emitter 101; and the light emitter 101 can be provided closer to the deflecting surface 1020 on the target area 500 side of the deflecting surface 1020. Therefore, it is possible to emit the scanning light 111 at a wide angle while preventing the size of the light emitting device 100 from becoming larger.

In addition, because a turning stage is not used to emit scanning light 111 at a wide angle, it is possible to prevent the light emitting device 100 from being greater in size and from increasing in weight. Furthermore, because a turning stage is not used, power consumption can be reduced, and disturbance due to vibration or impact during turning of a turning stage does not occur; therefore, the desired accuracy of the light irradiating position can be obtained.

In the present embodiment, the light emitter 101 includes the semiconductor laser 1011 and the light guide lens 1012 to irradiate the deflecting surface 1020 of the MEMS mirror 102 with laser light whose spread angle is adjusted by the light guide lens 1012. Therefore, the spread angle of the scanning light 111 from the MEMS mirror 102 is adjusted to a predetermined angle, and the size and spatial resolution of the area where the scanning light 111 irradiates can be adjusted.

In the present embodiment, the spread angle θy of the scanning light 111 with respect to the Y direction along the turning axis 110 is greater than the spread angle θx of the scanning light 111 with respect to the X direction perpendicular to the turning axis 110.

With regard to the X direction, deflecting by the MEMS mirror 102 enables to obtain the desired size of the target area 500. Therefore, by reducing the beam spread angle θx and reducing the beam diameter of the scanning light 111 with respect to the X direction, it is possible to increase the light emission spatial resolution for the target area 500 with respect to the X direction.

If θx is 0 degrees, the beam does not spread, so that the spatial resolution can be desirably kept constant regardless of the distance to an object in the target area 500. The "0 degrees" may be approximately "0 degrees". In this context, "approximately 0 degrees" means not to require perfect "0 degrees" without any error, and means to allow such a degree of divergence or convergence generally being able to be recognized as an error due to lens aberration or the like, or allow such a spread angle as to enable irradiating the target area 500 with the scanning light without any gap. The same manner shall apply to a case where the term "approximately 0 degrees" is used hereinafter.

With regard to the Y direction, because deflecting is not performed by the MEMS mirror 102, the desired size of the target area 500 can be obtained by increasing the spread angle θy.

When the light emitting device 100 is applied to an on-board LIDAR device or the like, it is desirable that the X direction is set to the horizontal direction, because it is possible to detect presence or absence of an object or the distance to an object at a wide area by widening the maximum scan angle Sx by the MEMS mirror 102. On the other hand, with regard to the height direction corresponding to the Y direction, an area where an object may exist is limited to an area near the surface of the ground, and thus, it is sufficient to provide a relatively small area defined by the spread angle θy of the beam.

Second embodiment

Next, an object detecting device 200 according to a second embodiment will be described.

Fig. 4 is a diagram partially illustrating an example of a configuration of an object detecting device 200. As illustrated in Fig. 4, the object detecting device 200 includes a light emitting device 100, a light receiving lens 103, a light receiving device 104, and a control unit 300.

Laser light emitted by the emitting device 100 and irradiating the target area 500 is reflected or scattered by an object present in the target area 500 and is thus returned to the object detecting device 200. Return light 121, indicated by an alternate long and short line in Fig. 4, is laser light reflected or scattered back by such an object. In other words, return light 121 is at least one of reflected light and scattered light from an object present in the target area 500.

The return light 121 is then reflected by the MEMS mirror 102 and incident on the light receiving device 104 through the light receiving lens 103.

The object detecting device 200 obtains and outputs object information indicating presence or absence of an object in the target area 500 or a distance to the object based on an emitting time when the light emitter 101 of the light emitting device 100 emits laser light and a receiving time when the light receiving device 104 receives the return light.

The spread angle of scanning light 111 with respect to the direction along the turning axis is greater than the spread angle of the scanning light 111 with respect to the direction perpendicular to the turning axis. In the present embodiment, both of the light emitting device 100 and the light receiving device 104 are on a plane including the turning axis 110. In this case, the deflecting surface 1020 of the MEMS mirror 102 can be reduced in size along the direction perpendicular to the turning axis 110. Thus, the deflecting surface 1020 of the MEMS mirror 102 can be increased in size along the direction along the turning axis 110 while surface deformation of the MEMS mirror 102 with respect to the direction perpendicular to the turning axis 110 can be reduced.

With reference to the present embodiment, an example in which a so-called uniaxial scanning MEMS mirror 102, which turns only with the turning axis 110 and does not turn in a direction perpendicular to the turning axis 110, is used, is described. However, a biaxial scanning MEMS mirror as described in a later described embodiment may be used instead.

The light receiving lens 103 is an example of a light receiving optical system and is a condenser lens for efficiently condensing return light 121. The light receiving lens 103 is not limited to a single lens, but may be a combination of a plurality of lenses, or may be a combination of optical elements such as a lens, a mirror, and a prism.

The light receiving device 104 is an example of a light receiver and receives return light 121 and outputs a voltage signal corresponding to the received light intensity. As the light receiving device 104, a photodiode (PD) or an avalanche photodiode (APD), a single photo avalanche photodiode (SPAD) which is a Geiger Mode APD, a time of flight (TOF) sensor, or the like may be used. The light receiving device 104 is provided in a common electrical circuit board 105 on which also the semiconductor laser 1011 of the light emitting device 100 is mounted.

The control unit 300 outputs control signals to the semiconductor laser 1011 and the MEMS mirror 102 of the light emitting device 100 to control driving these devices. The control unit 300 receives a voltage signal according to the light intensity of return light output by the light receiving device 104 and obtains and outputs object information with respect to the target area 500 based on the voltage signal.

According to the present embodiment, light 121 returning through the deflecting surface 1020 of the MEMS mirror 102 is received by the light receiving device 104. Because the speed of light is sufficiently high compared to the turning speed of the MEMS mirror 102, synchronization of scanning light 111 and return light 121 can be achieved as a result of return light 121 being received through the deflecting surface 1020 of the MEMS mirror 102. Thus, return light 121 is distinguished from noise light, and reflected or scattered light of scanning light 111 from an object is received while the influence of noise light is reduced, and therefore, the object can be detected with a high signal-to-noise (S/N) ratio.
<Example of hardware configuration of control unit 300>

Next, a hardware configuration of the control unit 300 will be described. Fig. 5 is a block diagram illustrating an example of a hardware configuration of the control unit 300.

As illustrated in Fig. 5, the control unit 300 includes a central processing unit (CPU), a read-only memory (ROM) 302, a random access memory (RAM) 303, a solid state drive (SSD) 304, a light source driving circuit 305, a sensor interface (I/F) 306, an input and output I/F 307, and a scanning driving circuit 308. These elements are electrically connected to each other by a system bus 309.

The CPU 301 is a processor and implements controls and functions of the entire control unit 300 by reading programs and data from memories such as ROM 302 and SSD 304 onto the RAM 303 and executing processes. Some or all of the functions implemented by the CPU 301 may be implemented by electronic circuits such as application specific integrated circuits (ASIC) or field-programmable gate array (FPGA).

The ROM 302 is a non-volatile semiconductor memory capable of storing programs and data even when after the power is turned off. The ROM 302 stores programs and data such as a basic input/output system (BIOS) that is executed when the control unit 300 starts, and OS settings.

The RAM 303 is a volatile semiconductor memory that temporarily stores programs and data.

The SSD 304 is a non-volatile memory in which programs or various data for executing processes by the control unit 300 are stored. The SSD may be a hard disk drive (HDD), etc.

The light source driving circuit 305 is electrically connected to the semiconductor laser 1011 and is an electrical circuit that outputs a drive signal, such as a drive voltage, to the semiconductor laser 1011 according to a control signal input from the CPU 301 or the like.

As a voltage waveform of the drive signal, a square or sinusoidal wave or a predetermined waveform can be used. The light source driving circuit 305 can vary the frequency of the voltage waveform to modulate the frequency of the drive signal.

The sensor I/F 306 is electrically connected to the light receiving device 104 and is an interface for receiving a voltage signal output by the light receiving device 104.

The input and output I/F 307 is connected to an external device such as an external controller provided in a mobile body such as a vehicle or a personal computer (PC) and is an interface for receiving data such as detection conditions and transmitting data such as detected object information. The input and output I/F 307 may be configured to be connected to a network such as the Internet for data transmission and reception.

The scanning driving circuit 308 is electrically connected to the MEMS mirror 102 and is an electrical circuit that outputs a drive signal, such as a drive voltage, to the MEMS mirror 102 according to a control signal input from the CPU 301 or the like.
<Example of functional configuration of control unit 300>

Next, a functional configuration of the control unit 300 will be described. Fig. 6 is a block diagram illustrating an example of a functional configuration of the control unit 300. As illustrated in Fig. 6, the control unit 300 includes a light source control unit 310, a light reception signal obtaining unit 311, a scanning control unit 312, an object information obtaining unit 313, and an object information output unit 314.

The functions of the light source control unit 310, the scanning control unit 312, and the object information obtaining unit 313 are implemented by executing of predetermined programs by the CPU 301 or the like. The function of the light reception signal obtaining unit 311 is implemented by the sensor I/F 306 or the like, and the function of the object information output unit 314 is implemented by the input and output I/F 307 or the like.

The light source control unit 310 controls emission of laser light from the semiconductor laser 1011. The light reception signal obtaining unit 311 obtains a voltage signal corresponding to light intensity of return light 121 output by the light receiving device 104 and outputs the voltage signal to the object information obtaining unit 313. The scanning control unit 312 controls driving to turn the MEMS mirror 102.

The object information obtaining unit 313 receives information indicating an emitting time when the light emitter 101 emits light 112 from the light source control unit 310, and receives information indicating a receiving time when the light receiving device 104 receives return light 121 from the light reception signal obtaining unit 311. Object information obtained based on a time difference between an emitting time and a receiving time is output to an external device through the object information output unit 314.

More specifically, object information includes a distance image. A distance image is an image generated from arranging distance data representing the distance to an object obtained for each pixel in two dimensions according to the position of the pixel, and is, for example, an image generated by transforming the distance to the brightness of the pixel. In other words, a distance image is three-dimensional information indicating the position of an object in the target area 500.

An example of an object detecting method is a time of flight (TOF) method. Because the TOF method can apply the well-known technique disclosed in Japanese Unexamined Patent Application Publication No. 2018-77143, a more detailed description will now be omitted.
<Example of noise light reducing condition>

In the present embodiment, laser light emitted by the semiconductor laser 1011 is transformed into divergent light by the light guide lens 1012 and incident on the deflecting surface 1020 of the MEMS mirror 102. In this case, stray light may be generated by multiple rays contained in the beam of divergent light incident on the deflecting surface 1020 of the MEMS mirror 102 at various angles. Stray light means light that does not irradiate the target area 500. When such stray light reaches the light receiving device 104 through the light receiving lens 103, such light may become noise light with respect to return light 121.

In order to reduce such noise light, in the present embodiment, the position where the central axis 112c of emitted light 112 intersects the deflecting surface 1020 of the MEMS mirror 102 is spaced more than a predetermined distance from the position where the light receiving axis of the light receiving device 104 intersects the deflecting surface 1020 of the MEMS mirror 102.

The central axis 112c of emitted light 112 is an axis extending from the center of the emitting surface of the semiconductor laser 1011 in the direction normal to the emitting surface. When a plurality of light emitting sections exist, such as a VCSEL or the like, the axis extending from the center of the area, at which the light emitting sections are arranged, in the direction normal to the light emitting surface corresponds to the central axis 112c of emitted light 112. When laser light from the semiconductor laser 1011 is reflected by a mirror or the like for the light path to be bent and irradiates the MEMS mirror 102, the central axis 112c of the emitted light 112 is determined in a state in which the bent light path is expanded (a state in which the light path is extended straight without being bent).

The light receiving axis 104c of the light receiving device 104 is an axis extending in the direction normal to the light receiving surface from the center of the light receiving surface of the light receiving device 104. When the light receiving device 104 includes a plurality of light receiving devices on a plane, such as a light receiving device array, the light receiving axis 104c is an axis extending from the center of the light receiving surface where the plurality of light receiving devices are arranged in the direction normal to the light receiving surface. When return light 121 is reflected by a mirror or the like for the light path to be bent and is received by the light receiving device 104, the light receiving axis 104c of the light receiving device 104 is determined in a state in which the bent light path of the return light is expanded.

An arrangement is made in such a manner that the turning axis 110 is approximately parallel to a straight line connecting a position where the central axis 112c of emitted light 112 intersects the deflecting surface 1020 and a position where the light receiving axis 104c extending in the direction normal to the light receiving surface through the center of the light receiving surface of the light receiving device 104 intersects the deflecting surface 1020.

A more specific description will now be made with reference to Fig. 7. Fig. 7 is a diagram illustrating an example of a condition for reducing noise light.

In Fig. 7, the position at which the central axis 112c of emitted light 112 that is emitted from the light emitter 101 to irradiate the deflecting surface 1020 intersects the deflecting surface 1020 is referred to as an irradiation center position Qi, and the position at which the light receiving axis 104c of the light receiving device 104 intersects the deflecting surface 1020 is referred to as a light receiving center position Qr. The distance between the irradiation center position Qi and the light receiving center position Qr is indicated as D.

When the intersecting position of the light receiving axis 104c at the deflecting surface 1020 is included in the area where divergent light from the light guide lens 1012 irradiates the deflecting surface 1020, diffused light from the deflecting surface 1020 easily reaches the light receiving device 104. Taking into account also this point, the distance D is determined for formula (1) below to be satisfied.

In formula (1), θy denotes the spread angle of emitted light 112 with respect to the Y direction. The spread angle is the angle between respective lines passing through, along the light propagation direction, both end positions each having the light intensity of 50% relative to the peak light intensity near the center of the beam with respect to the light intensity distributions of the beam of emitted light 112. φy denotes the tilt angle with respect to the Y direction of the central axis 112c of emitted light 112 relative to the normal S to the MEMS mirror 102.

The distance Le is the distance between the intersection point of the central axis 112c of emitted light 112 at the deflecting surface 1020 and the diverging starting position T of the emitted light 112. The diverging starting point position is a starting point where diverging light starts to diverge in the propagation direction (optical axis direction) of the diverging light.

In formula (1), the sign "±" is such that plus or minus is selected according to the positional relationship between the emitted light 112 and the return light 121 with respect to the Y direction. Plus is selected when the return light 121 is in the Y direction with respect to the emitted light 112. Minus is selected when the emitted light 112 is in the Y direction with respect to the return light 121.

In the above-described example, the both ends are determined on the basis of the light intensity of 50%, but there is no limitation to this way. As long as the light intensity value to be used is 50% or less, the distance D can be appropriately determined based on formula (1).

<Example of operation of eccentric free-form surface
light receiving lens 103>
In the present embodiment, the central axis 112c of emitted light 112 is tilted with respect to a plane 113 perpendicular to the turning axis 110 of the MEMS mirror 102, so it is desirable that the light receiving lens 103 be also tilted with respect to the plane 113.

In this case, if the light receiving lens 103 is an axisymmetric lens, a satisfactory beam shape on the light receiving device 104 may not be obtained because aberrations may not be removed. Therefore, in the present embodiment, the light receiving lens 103 includes an aspherical surface. It is more desirable to form the aspheric surface as an eccentric free-form surface that can correct the inclination of an optical axis.

Fig. 8 is a diagram illustrating an example of a configuration of the light receiving lens 103 including an eccentric free-form surface 103s. The eccentric free-form surface 103s has a shape that is non-axisymmetric with respect to the light receiving axis 104c of the light receiving device 104 and can correct the inclination with respect to the Y direction of the light receiving axis 104c corresponding to an optical axis with respect to the MEMS mirror 102.
<Effect of object detecting device 200>

As described above, according to the present embodiment, the object detecting device 200 includes the light emitting device 100 and the light receiving device 104 that receives at least one of reflected light or scattered light of the scanning light 111 from an object present in the target area 500, so that the object present in the target area 500 can be detected.

In the present embodiment, return light 121 is received by the light receiving device 104 through the deflecting surface 1020 of the MEMS mirror 102, so that scanning light 111 and return light 121 are synchronized. Therefore, it is possible to receive at least one of reflected light or scattered light of the scanning light 111 from an object by reducing the influence of noise light, and detect the object with a high SN ratio.

In the present embodiment, the distance between a position where the central axis 112c of the emitted light 112 intersects the deflecting surface 1020 of the MEMS mirror 102 and a position where the light receiving axis 104c of the light receiving device 104 intersects the deflecting surface 1020 of the MEMS mirror 102 is made to be more than a predetermined distance.

This prevents stray light from reaching the light receiving device 104 through the light receiving lens 103, reduces noise light, and enables detecting an object with a higher SN ratio.

In the present embodiment, an aspherical surface, such as an eccentric free-form surface, is included in the light receiving lens 103. Accordingly, aberrations generated due to tilting of the light receiving lens 103 with respect to the plane 113 perpendicular to the turning axis 110 are reduced, and a satisfactory beam shape can be obtained on the light receiving device 104.

In the present embodiment, the object information output unit 314 outputs object information obtained based on an emitting time of emitted light 112 and a receiving time of return light 121 at the light receiving device 104. This allows object information concerning the target area 500 to be provided to an external device, such as a vehicle controller.

Because the effect other than the above-described effect is the same as the effect of the first embodiment, the description will not be repeated.

Third embodiment

Next, an object detecting device 200a according to a third embodiment will be described.

Fig. 9 is a diagram partially illustrating a configuration of the object detecting device 200a.

As illustrated in Fig. 9, the object detecting device 200a includes a light emitting device 100a. The light emitting device 100a includes a MEMS mirror 102a. The MEMS mirror 102a is configured to turn a deflecting surface 1020 around a turning axis 110 and further turn the deflecting surface 1020 around a perpendicular turning axis 130 perpendicular to the turning axis 110. Thus, emitted light 112 from the light emitter 101 can be deflected not only with respect to the X direction but also with respect to the Y direction.

Fig. 10 is a diagram illustrating an example of a configuration of the MEMS mirror 102a. As illustrated in Fig. 10, the MEMS mirror 102a includes a moving section 1021 with the deflecting surface 1020 formed on a surface of the moving section 1021, a torsion bar 1022, a support frame 1023, and drive beams 1024.

The deflecting surface 1020 reflects and deflects emitted light 112. The torsion bar 1022 supports the moving section 1021 from both sides with respect to the X direction and turns the moving section 1021 around the perpendicular turning axis 130. The support frame 1023 supports the torsion bar 1022, and the drive beams 1024 turn the support frame 1023 around the turning axis 110.

Thus, the MEMS mirror 102a can turn the deflecting surface 1020 around the turning axis 110 and also around the perpendicular turning axis 130.

Because the moving section 1021 in the MEMS mirror 102a is small and is formed thin, when a turning angle is great, a deformation may occur due to the resistance of a gas such as air. The "turning angle" is an angle range for which the moving section 1021 is turned. In response to such a deformation of the moving section 1021, also a deformation of the deflecting surface 1020 formed on the surface of the moving section 1021 may occur, resulting in a degradation in the beam shape of emitted light 112 reflected by the deflecting surface 1020.

According to the present embodiment, the moving section 1021 is formed in such a manner that the Y direction length is longer than the X direction length, and a turning angle of the moving section 1021 around the perpendicular turning axis 130 is smaller than a turning angle of the moving section 1021 around the turning axis 110.

The greater the moving section 1021, the easier the moving section 1021 is to deform due to the resistance of a gas, but, by reducing a turning angle of the moving section 1021 with respect to the longer length direction and increasing a turning angle of the moving section 1021 with respect to the shorter length direction, the moving section 1021 is not appreciably deformed due to being turned.

Although the deflecting surface 1020 is formed on the moving section 1021 in the example described above, a surface of the moving section 1021 may be formed as being specular, and the surface of the moving section 1021 may have a function of reflecting and deflecting emitted light 112.

As described above, in the present embodiment, the MEMS mirror 102a is such that the deflecting surface 1020 is turned around the turning axis 110, and also, the deflecting surface 1020 is turned around the perpendicular turning axis 130 perpendicular to the turning axis 110, so that emitted light 112 from the light emitter 101 can be deflected not only with respect to the X direction but also with respect to the Y direction. Accordingly, as a result of the deflecting surface 1020 of the MEMS mirror 102a being turned with respect to the Y direction so that the reflected light is deflected with respect to the Y direction, the desired size of the target area 500 along the Y direction can be obtained without increasing of the spread angle θy of the scanning light 111 with respect to the Y direction.

Because it is thus possible to reduce the spread angle θy with respect to the Y direction of scanning light 111, it is possible to improve the spatial resolution of the target area 500 along the Y direction.

Further, in the present embodiment, the moving section 1021 of the MEMS mirror 102a is formed in such a manner that the Y direction size is long and the X direction size is short, and a turning angle of the moving section 1021 around the perpendicular turning axis 130 is smaller than a turning angle of the moving section 1021 around the turning axis 110. Therefore, it is possible to reduce a deformation of the moving section 1021 due to being turned, and to reduce a deterioration in the beam shape of scanning light 111 due to a deformation of the deflecting surface 1020 caused by a deformation of the moving section 1021.

When the light emitting device 100 is used in a LIDAR device or the like provided in a vehicle, the height direction (corresponding to the Y direction) size of an area where an object is present is limited to the size corresponding to an area near the surface of the ground. Therefore, even as a result of a turning angle of the moving section 1021 around the perpendicular turning axis 130 being made smaller than a turning angle around the turning axis 110 and the maximum scan angle Sy with respect to the Y direction being made smaller than the maximum scan angle Sx with respect to the X direction, a relatively small area determined by the maximum scan angle Sy may be sufficient.

Because the effects other than the above-described effects are the same as the effects of the first and second embodiments, the description will not be repeated.

Fourth embodiment

Next, an object detecting device 200b according to a fourth embodiment will be described. Fig. 11 is a block diagram illustrating an example of a functional configuration of a control unit 300b included in the object detecting device 200b.

As illustrated in Fig. 11, the control unit 300b includes a distortion correcting unit 315, an object image information obtaining unit 316, a complemented object information obtaining unit 317, and a complemented object information output unit 318. The functions of the distortion correcting unit 315, the object image information obtaining unit 316, and the complemented object information obtaining unit 317 are implemented by executing of predetermined programs by the CPU 301 (see Fig. 5), and the function of the complemented object information output unit 318 is implemented by the input and output I/F 307 or the like.

The distortion correcting unit 315 receives a right eye image captured by a right camera 141 of a stereo camera 140 and a left eye image captured by a left camera 142 of the stereo camera 140 and corrects image distortions of the right eye image and the left eye image, respectively. Examples of image distortions include a barrel-shaped or pin-cushion distortion around the outer edge of the image and a trapezoidal distortion. The distortion correcting unit 315 outputs corrected right eye image and left eye image to the object image information obtaining unit 316. Each of the right camera 141 and left camera 142 is an example of an image capturing unit.

The object image information obtaining unit 316 generates a distance image based on parallax detected through image processing using the input right eye image and left eye image, and outputs the generated distance image to the complemented object information obtaining unit 317.

The complemented object information obtaining unit 317 obtains complemented object information based on object information input from the object information obtaining unit 313 and a distance image input from the object image obtaining unit 316. Complemented object information means object information obtained from a set of object information from among plural sets of object information obtained from different manners, respectively, being complemented with the use of another set of object information from among the plural sets of object information.

In the present embodiment, one of the plural sets of object information is object information, such as a distance information image detected by the TOF method, and the other is object information, such as a distance image detected by the stereo camera method.

In the TOF method, high-precision distance detection is possible without depending on the distance to the object. However, because return light of scanning light 111 that is emitted after the beam is spread is used, the in-plane spatial resolution may be degraded.

In the stereo camera method, high in-plane spatial resolution is obtained in accordance with the resolution of the right camera 141 and the left camera 142, but the detection accuracy of the distance may be low depending on the distance to the object.

By combining both types of information, high precision distance detection can be achieved with high in-plane spatial resolution. For example, one or more pixels corresponding between a distance image obtained by the object information obtaining unit 313 and a distance image obtained by the object image information obtaining unit 316 are determined. For the corresponding pixels, distance detection values of the distance image obtained by the object information obtaining unit 313 are used, whereas for the other pixels, the distance detection values of the distance image obtained by the object image information obtaining unit 316 and corrected based on the distance detecting values of the corresponding pixels are used, and thus, a complemented distance image is obtained.

Such a complemented distance image is obtained from complementing in-plane spatial resolution of a TOF-based distance image with the use of a stereo camera-based distance image, and is an example of complemented object information.

The complemented object information obtaining unit 317 outputs an obtained complemented distance image to an external device such as a vehicle controller via the complemented object information output unit 318.

As described above, the present embodiment outputs a complemented distance image obtained based on a distance image obtained through the TOF method and a distance image obtained through the stereo camera method. A high distance detection accuracy distance image with high in-plane spatial resolution can be obtained from complementing of in-plane spatial resolution of a TOF-based distance image being by a stereo camera-based distance image.

With reference to the present embodiment, an example of complementing in-plane spatial resolution of a TOF-based distance image has been described. However, the present invention is not limited to such a manner. For example, color information or the like not obtained by the TOF-based method may be used to complement a TOF-based distance image, with the use of an image captured by the right camera 141 or the left camera 142. By complementing a TOF-based distance image by color information, when the object detecting device 200b is applied to a vehicle, etc., color information concerning a traffic signal, a traffic sign, or the like can be used. Other information may also be used to complement a TOF-based distance image.

As an example of the image capturing unit, a stereo camera having two cameras of right camera 141 and left camera 142 has been described. However, there is no limitation to a stereo camera, and a single camera may be used instead.

Because the effects other than the above-described effects are the same as the effects of the first through third embodiments, the description will not be repeated.

Fifth embodiment

Next, a mobile body according to a fifth embodiment will be described.

Fig. 12 is a diagram illustrating an example of a configuration of a mobile body 1 including an object detecting device 200. The mobile body 1 is an unmanned transport vehicle that transports a cargo to a destination.

The object detecting device 200 is provided at a front portion of the mobile body 1 and obtains object information such as a distance image with respect to the Z direction of the mobile body 1. Using an output of the object detecting device 200, it is possible to detect object information, such as presence or absence of an object such as an obstacle in the Z direction of the mobile body 1, and a position of the object.

Fig. 13 is a block diagram illustrating an example of a hardware configuration of the mobile body 1. As illustrated in Fig. 13, the mobile body 1 includes the object detecting device 200, a display device 30, a position control device 40, a memory 50, and a sound alarm generating device 60. These devices are electrically connected via a bus 70 capable of transmitting signals and data.

In the present embodiment, a travelling managing apparatus 10 includes the object detecting device 200, the display device 30, the position control device 40, the memory 50, and the sound alarm generating device 60. The travelling managing apparatus 10 is provided in the mobile body 1. The travelling managing apparatus 10 is electrically connected to a main controller 80 of the mobile body 1.

The display device 30 is a display, such as a liquid crystal display (LCD) that displays three-dimensional information obtained by the object detecting device 200 and various setting information related to the mobile body 1. The position control device 40 is an arithmetic device, such as a CPU, that controls the position of the mobile body 1 based on object information obtained by the object detecting device 200. The sound alarm generating device 60 is a device that determines whether an obstacle is avoidable based on three-dimensional data obtained by the object detecting device 200 and notifies a surrounding personnel when determining that the obstacle cannot be avoided. For this purpose the sound alarm generating device 60 includes a speaker or the like.

Thus, the mobile body including the object detecting device 200 can be provided.

It should be noted that the mobile body including the object detecting device 200 is not limited to an unmanned vehicle. It is also possible to provide the object detecting device in a vehicle, such as a car, or in a flight vehicle, such as a drone, or the like. In addition to such mobile bodies, it is also possible to provide the object detecting device 200 in an information terminal such as a smartphone or a tablet.

With reference to the embodiments, examples in each of which the object detecting device 200 include the configuration and functions of the control unit 300 have been described, but there is no limitation to such a manner. A part or all of the configuration and functions of the control unit 300 may be provided in an apparatus such as an external controller provided in the mobile body 1 in which the object detecting device 200 is provided, or may be provided in an apparatus connected to the object detecting device 200.

Because the effects other than the above-described effects are the same as the effects of the first through the fourth embodiments, the description will not be repeated.

The light emitting devices, object detecting devices, and mobile bodies have been described with reference to the embodiments. However, the present invention is not limited to the embodiments, and various modifications and improvements can be made without departing from the scope of the claimed invention.

Variants of embodiments

Variants of the light emitting device 100 and the object detecting device 200 according to the embodiments will now be described.

Fig. 18 is a diagram illustrating a spread angle of light with respect to the Y direction in a first variant of the light emitting device 100. Fig. 19 is a diagram illustrating a spread angle of light with respect to the X direction in a second variant of the light emitting device 100.

In the first embodiment, the light emitter 101 irradiates the deflecting surface 1020 with light in such a manner that the central axis of the emitted light 112 intersects a plane 113 perpendicular to the turning axis 110; and the angles θx and θy are previously determined. In the configurations illustrated in Figs. 18 and 19, a reflected position P where the central axis 112c of emitted light 112 intersects the deflecting surface 1020 is included in a plane 113 perpendicular to the turning axis 110 of the deflecting surface 1020. Fig. 18 illustrates a case where θy is previously determined, and Fig. 19 illustrates a case where θx is previously determined.

Even in each of such cases, the spread angles θx and θy can be adjusted to certain values, and thus, the size or the spatial resolution of an area that scanning light 111 irradiates can be adjusted.

Even in each of the first and second variants, the spread angle θy of scanning light 111 with respect to the Y direction along the turning axis 110 is greater than the spread angle θx of scanning light 111 with respect to the X direction perpendicular to the turning axis 110.

With respect to the X direction, scanning by the MEMS mirror 102 enables to obtain the desired size of the target area 500. Therefore, by reducing the beam spread angle θx and reducing the beam diameter with respect to the X direction of scanning light 111, it is possible to increase the spatial resolution of irradiation with emitted light with respect to the X direction of the target area 500.

As a result of setting θx to approximately 0 degrees to form approximately parallel light, a beam does not spread with respect to the X direction, so that the spatial resolution can be more desirably kept constant regardless of the distance to an object to be detected from the target area 500. With respect to the Y direction, because scanning is not performed by the MEMS mirror 102, a desired size of the target area 500 can be obtained by increasing of the spread angle θy.

Thus, the light emitter can be reduced in size along the X direction, the spread angle θx of emitted light can be sufficiently reduced, and the spread angle of scanning light with respect to the scanning direction can be reduced. Accordingly, even when the scanning area of scanning light is brought close to the light emitter, it is possible to prevent mechanical vignetting with respect to scanning light otherwise occurring due to the light emitter and to reduce the size of the device.

Further, as a result of the size of the deflecting surface 1020 in the MEMS mirror 102 being increased in the Y direction, an area of the deflecting surface 1020 needed for deflecting emitted light 112 having a great spread angle θy can be obtained, and the desired light amount of the scanning light 111 can be obtained, to implement a more desirable configuration.

Fig. 20 is a diagram illustrating a spread angle of light with respect to the Y direction according to a third variant of the light emitting device 100. In the present variant, the spread angle with respect to the Y direction of emitted light 112 that is emitted by the light emitter 101 to irradiate the deflecting surface 1020 is θy, and the tilt angle of the central axis 112c of emitted light 112 from the normal S to the deflecting surface 1020 with respect to the Y direction is φy. As a result of the spread angle θy of emitted light 112 with respect to the Y direction and the tilt angle φy of the central axis 112c of emitted light 112 from the normal S to the deflecting surface 1020 being determined to satisfy the following formula, it is possible to reduce mechanical vignetting of emitted light 112 caused by the light emitter 101 itself. This allows wide angle irradiation with respect to the Y direction.
φy≧θy/2

Fig. 14 is a diagram partially illustrating another first example of the configuration of the object detecting device 200. In the example of Fig. 14, the light receiving lens 103 and the light receiving device 104 are provided in the direction reverse to the Y direction of the light emitter 101. With reference to each of the first through fifth embodiments described above, an example in which the light receiving lens 103 and the light receiving device 104 are provided in the Y direction of the light emitter 101 has been described. However, the light receiving lens 103 and the light receiving device 104 may be provided in the direction, reverse to the Y direction, of the light emitter 101, as illustrated in Fig. 14.

Fig. 15 is a diagram illustrating an example of a noise light reducing condition with respect to the configuration of Fig. 14. Compared with the example illustrated in Fig. 7, only the Y direction position of the light receiving lens 103 and the light receiving device 104 with respect to the light emitter 101 is different, and the noise light reducing condition is the same as the noise light reducing condition described with reference to Fig. 7.

Next, Fig. 16 is a diagram partially illustrating another second example of the configuration of the object detecting device 200. In the example of Fig. 16, the light receiving lens 103 and the light receiving device 104 are away from the light emitter 101. With reference to each of the first through fifth embodiments, an example in which the light receiving lens 103 and the light receiving device 104 are provided side by side with the light emitter 101 has been described. However, as illustrated in Fig. 16, the light receiving lens 103 and the light receiving device 104 may be away from the light emitter 101, and provided at any position.

As illustrated in Fig. 16, the light receiving device 104 may be a line sensor in which photodiodes or the like are arranged in one dimension.

Next, Fig. 17 is a diagram partially illustrating another third example of the configuration of the object detecting device 200. In the example of Fig. 17, the MEMS mirror 102 includes the deflecting surface 1020 having a longer size along the X direction and a shorter size along the Y direction. The position where the central axis 112c of emitted light 112 intersects the deflecting surface 1020 and the position where the light receiving axis 104c of the light receiving device 104 intersects the deflecting surface 1020 are spaced apart along the X direction.

Thus, the deflecting surface 1020 having the shorter X direction length and the longer Y direction length may be used.

Fig. 21 is a diagram partially illustrating another fourth example of the configuration of the object detecting device 200. Fig. 21 is used to define the Y direction length M of the deflecting surface. Fig. 21 illustrates a range of being irradiated with emitted light 112 as E along the Y direction on the deflecting surface 1020. A range of being irradiated with return light 121 along the Y direction on the deflecting surface 1020 is illustrated as R. The range E can be expressed by the following formula (2):

Regarding the range R, in order to effectively receive return light 121 at the light receiving lens 103 by a sufficient amount of light and direct the light to the light receiving device 104, the range R equivalent to the range E is required on the deflecting surface 1020.

On the deflecting surface 1020, as a result of the range R and the range E not sharing any area, and the length M satisfying the following formula, it is possible to reduce ghosting and allow a great angle of deflecting scanning light to scan the target area with respect to the Y direction.

Although the example in which the light emitting device 100 is provided in the object detecting device 200 is illustrated, the present invention is not limited to such a manner, and the light emitting device 100 can be provided in any one of various devices. Light emitted by the light emitting device 100 is not limited to laser light, and may be light having no directivity, or may be an electromagnetic wave having a long wavelength, such as a wave of a radar.

The functions of the embodiments described above may be implemented by one or more processing circuits. As used herein, a "processing circuit" may be a processor programmed to perform each function described above by software, such as a processor implemented in an electronic circuit, an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array (FPGA), or a known circuit module designed to perform each function described above.

The present application is based on and claims priority to Japanese patent application No. 2019-226764 filed on December 16, 2019, and Japanese patent application No. 2020-165784 filed on September 30, 2020. The entire contents of Japanese patent application No. 2019-226764 and Japanese patent application No. 2020-165784 are hereby incorporated herein by reference.

[PTL 1]　　Japanese Unexamined Patent Application Publication No. 2019-502107

1 Mobile body
10 Traveling managing apparatus
100 Light emitting device
200 Object detecting device
101 Light emitter
1011 Semiconductor laser (an example of a light source)
1012 Light guide lens (an example of an adjuster)
102 MEMS mirror (an example of a scanner)
1020 Deflecting surface
1021 Moving section
1022 Torsion bar
1023 Support frame
1024 Drive beam
103 Light receiving lens (an example of a light receiving optical system)
103s Eccentric free-form surface
104 Light receiving device (an example of a light receiver)
105 Electrical circuit board
110 Turning axis
111 Scanning light
111c Central axis of scanning light
112 Emitted light (an example of a light emitted from a light emitter)
112c Central axis of emitted light
113 Plane perpendicular to turning axis
121 Return light
130 Perpendicular turning axis
140 Stereo camera
141 Right Camera (an example of an image capturing unit)
142 Left camera (an example of an image capturing unit)
300 Control unit
310 Light source control unit
311 Light reception signal obtaining unit
312 Scanning control unit
313 Object information obtaining unit
314 Object information output unit
315 Distortion correcting unit
316 Object image information obtaining unit
317 Complemented object information obtaining section
318 Complemented object information output unit
500 Target area
D Distance
P Reflected position
Qi Irradiation center position
Qr Light receiving center position
Sx Maximum scan angle with respect to X direction
Sy Maximum scan angle with respect to Y direction
X Direction perpendicular to turning axis
Y Direction along turning axis
Z Direction intersecting both X direction and Y direction
η Angle at which central axis of emitted light intersects a plane perpendicular to turning axis
θy Spread angle of emitted light with respect to Y direction
φy Tilt angle with respect to Y direction

Claims

　　　　A light emitting device configured to emit scanning light to irradiate a target area, the light emitting device comprising:
　　　　a light emitter configured to emit light; and
　　　　a scanner including a deflecting surface configured to deflect light as a result of being turned around a turning axis, to generate the scanning light,
　　　　wherein
　　　　the light emitter is on a target area side of the deflecting surface, and
　　　　the light emitter is further configured to emit the light to the deflecting surface in such a manner that a central axis of the light intersects a plane perpendicular to the turning axis.
　　　　The light emitting device according to claim 1,
　　　　wherein
　　　　the light emitter includes:
　　　　a light source, and
　　　　an adjuster configured to adjust a spread angle of the light emitted from the light source, to generate the light to be emitted from the light emitter.
　　　　A light emitting device configured to emit scanning light to a target area, the light emitting device comprising:
　　　　a light emitter configured to emit light; and
　　　　a scanner including a deflecting surface configured to deflect the light as a result of being turned around a turning axis, to generate the scanning light,
　　　　wherein
　　　　the light emitter includes a light source, and an adjuster configured to adjust a spread angle of light emitted from the light source, to generate light to be emitted from the light emitter,
　　　　wherein
　　　　the adjuster is further configured to adjust the light emitted from the light source in such a manner that a spread angle of the light emitted from the light emitter with respect to a direction along the turning axis is to be greater than a spread angle of the light emitted from the light emitter with respect to a direction perpendicular to the turning axis.
　　　　The light emitting device according to any one of claims 1-3,
　　　　wherein
　　　　with respect to the direction along the turning axis, a tilt angle φy at which the central axis of the light emitted from the light emitter is tilted with respect to a normal to the deflecting surface and a spread angle θy of the light emitted from the light emitter with respect to the direction along the turning axis satisfy a following formula:
　　　　φy≧θy/2.
　　　　The light emitting device according to any one of claims 1-4,
　　　　wherein
　　　　a spread angle of the scanning light with respect to the direction along the turning axis is greater than a spread angle of the scanning light with respect to a direction perpendicular to the turning axis.
　　　　The light emitting device according to any one of claims 1-5,
　　　　wherein
　　　　the scanning light is approximately parallel light with respect to a direction perpendicular to the turning axis.
　　　　The light emitting device according to any one of claims 1-6,
　　　　wherein
　　　　the scanner includes a moving section at which the deflecting surface is formed, and the moving section is longer along the direction along the turning axis than along a direction perpendicular to the turning axis.
　　　　The light emitting device according to any one of claims 1-7
　　　　wherein
　　　　the scanner is further configured to further turn the deflecting surface around an axis perpendicular to the turning axis, to deflect the light emitted from the light emitter with respect to the turning axis.
　　　　The light emitting device according to claim 8,
　　　　wherein
　　　　the scanner includes a moving section at which the deflecting surface is formed, and the moving section is longer along the direction along the turning axis than along a direction perpendicular to the turning axis, and
　　　　a turning angle of the moving section around an axis perpendicular to the turning axis is smaller than a turning angle of the moving section around the turning axis.
　　　　An object detecting device comprising:
　　　　the light emitting device according to any one of claims 1-9; and
　　　　a light receiver configured to receive reflected light or scattered light from an object present at the target area.
　　　　The object detecting device according to claim 10,
　　　　wherein
　　　　the light receiver is further configured to receive at least one of the reflected light and the scattered light through the deflecting surface of the light emitting device.
　　　　The object detecting device according to claim 11,
　　　　wherein
　　　　a length M along a direction along the turning axis of the deflecting surface satisfies a following formula:
Math 3

　　　　where:
　　　　Le denotes a distance between a position at which the central axis of the light emitted from the light emitter intersects the deflecting surface and a position from which the light emitted from the light emitter diverges,
　　　　θy denotes a spread angle of the light emitted from the light emitter with respect to the direction along the turning axis, and
　　　　φy denotes a tilt angle at which the central axis of the light emitted from the light emitter is tilted with respect to a normal to the deflecting surface.
　　　　The object detecting device according to claim 11 or 12,
　　　　wherein
　　　　the turning axis is approximately parallel with a line between a position at which the central axis of the light emitted from the light emitter intersects the deflecting surface and a position at which a light receiving axis extending in a direction along a normal to a light receiving surface of the light receiver through a center of the light receiving surface intersects the deflecting surface.
　　　　The object detecting device according to any one of claims 11-13,
　　　　wherein
　　　　a distance D along the direction along the turning axis between a position at which the central axis of the light emitted from the light emitter intersects the deflecting surface and a position at which a light receiving axis extending in a direction along a normal to a light receiving surface of the light receiver through a center of the light receiving surface intersects the deflecting surface satisfies a following formula (1)
Math 1

　　　　where:
　　　　Le denotes a distance between a position at which the central axis of the light emitted from the light emitter intersects the deflecting surface and a position from which the light emitted from the light emitter diverges,
　　　　θy denotes a spread angle of the light emitted from the light emitter with respect to the direction along the turning axis, and
　　　　φy denotes a tilt angle at which the central axis of the light emitted from the light emitter is tilted with respect to a normal to the deflecting surface.
　　　　The object detecting device according to any one of claims 10-12, further comprising
　　　　a light receiving optical system configured to converge at least one of the reflected light and the scattered light onto the light receiver,
　　　　wherein
　　　　the light receiving optical system includes an aspheric surface.
　　　　The object detecting device according to claim 15, wherein
　　　　the aspheric surface is an eccentric free-form surface.
　　　　The object detecting device according to any one of claims 10-16, further comprising
　　　　an object information output unit configured to output object information obtained based on a time at which the light emitted from the light emitter is emitted from the light emitter and a time at which at least one of the reflected light and the scattered light is received by the light receiver.
　　　　The object detecting device according to any one of claims 10-17, further comprising
　　　　an image capturing unit configured to capture an image of the object; and
　　　　a complemented object information output unit configured to output complemented object information obtained from complementing, with the image of the object, the object information obtained based on the time at which the light emitted from the light emitter is emitted from the light emitter and the time at which at least one of the reflected light and the scattered light is received by the light receiver.
　　　　A mobile body comprising:
　　　　the object detecting device according to any one of claims 10-18.