Patent ID: 12253629

DESCRIPTION OF EMBODIMENTS

Example embodiments of the present invention will be described below with reference to the drawings. Throughout the drawings, the same components or corresponding components are labeled with same references, and the description thereof may be omitted or simplified.

First Example Embodiment

FIG.1is a schematic diagram illustrating a general configuration of an object detection system including a ranging device100according to the first example embodiment. The object detection system includes a ranging device100and a control device200.

The ranging device100is a device such as a LiDAR device, for example. The ranging device100can acquire a distribution of the distance from the ranging device100by emitting a light in a predetermined range and detecting a reflection light from an object10. The ranging device100may be referred to as a sensor device in a more general sense. AlthoughFIG.1illustrates a single ranging device100, the object detection system may be configured to include a plurality of ranging devices100. Note that, in the present specification, light is not limited to visible light but may include invisible light that cannot be viewed by a naked eye, such as an infrared ray, an ultraviolet ray, or the like.

The control device200is a computer, for example. The control device200has an interface (I/F)210, a control unit220, a signal processing unit230, and a storage unit240. The interface210is a device that connects the control device200and the ranging device100so as to be able to communicate with each other in a wired or wireless manner. Thereby, the control device200and the ranging device100are communicably connected to each other. The interface210may be a communication device based on the specification such as Ethernet (registered trademark), for example. The interface210may include a repeater device such as a switching hub. When the object detection system has a plurality of ranging devices100, the control device200can control the plurality of ranging devices100by relaying via a switching hub or the like.

The control unit220controls the operation of the ranging device100. The signal processing unit230acquires distance information on an object10inside a detection range by processing a signal acquired from the ranging device100. The function of the control unit220and the signal processing unit230may be implemented when a processor such as a central processing unit (CPU) or the like provided in the control device200reads a program from a storage device and executes the program, for example. The storage unit240is a storage device that stores data acquired by the ranging device100, a program and data used in the operation of the control device200, or the like. Accordingly, the control device200has a function of controlling the ranging device100and a function of analyzing a signal acquired by the ranging device100.

The configuration of the object detection system described above is an example, and the object detection system may further include a device that collectively controls the ranging device100and the control device200. Further, the object detection system may be an integrated device in which the function of the control device200is incorporated in the ranging device100.

FIG.2is a schematic perspective view illustrating the structure of the ranging device100according to the first example embodiment.FIG.3illustrates the structure of the ranging device100viewed from the front.FIG.4illustrates the structure of the ranging device100viewed from the top. The structure of the ranging device100will be described with reference to these figures. Note that, the x-axis, the y-axis, and the z-axis illustrated in each drawing are solely provided for helping the description and are not intended to limit the arrangement direction of the ranging device100.

As illustrated inFIG.2, the ranging device100includes a base body110, a lid body120, a sensor unit130, a parabolic reflection mirror140, a position adjustment mechanism150, and a plane reflection mirror160, and a mounting portion170. Note that, the plurality of reflection mirrors included in the ranging device100(in this example, the parabolic reflection mirror140and the plane reflection mirror160) may be collectively called a reflection mirror unit.

The base body110is a member shaped in a rectangular plate and functions as a part of the housing of the ranging device100. The base body110has a function of fixing the sensor unit130, the parabolic reflection mirror140, the plane reflection mirror160or the like at a predetermined position.

The lid body120is a lid covering the base body110, and functions as a part of the housing of the ranging device100. In the internal space of the housing surrounded by the base body110and the lid body120, the parabolic reflection mirror140, the position adjustment mechanism150, and the plane reflection mirror160are arranged.

The sensor unit130is a two-dimensional LiDAR device. As illustrated inFIG.3, the sensor unit130can perform rotational scan about the rotation axis u. The sensor unit130includes a laser device for emitting laser light, and a photoelectric conversion element for receiving the reflection light reflected by the object10and converting it into an electric signal. As illustrated inFIG.2, the sensor unit130is arranged in a notch formed below the base body110and the lid body120. The light emitted from the sensor unit130is incident on the reflection surface140aof the parabolic reflection mirror140.

As an example of a distance detection scheme performed by the sensor unit130, a TOF (Time Of Flight) scheme may be used. The TOF scheme is a method for measuring a distance by measuring a period from emission of a light to reception of a reflected light.

Note that, the laser light emitted from the sensor unit130may be visible light but may be invisible light such as an infrared ray. In a use of detection of an article being put in or taken out from an article display shelf described later or the like, it is desirable that the emission light be invisible light so as not to give discomfort to a user. The laser light may be an infrared ray having a wavelength of around 905 nm, for example.

The parabolic reflection mirror140is a reflection mirror having a reflection surface140a. The reflection surface140aforms a parabola with a point on the rotation axis u as a focal point in a section (xy plane inFIG.3) perpendicular to the rotation axis u. In other words, the sensor unit130is arranged near the focal point of the parabola formed by the reflection surface140a, and the rotation axis u is arranged at a position passing through the focal point of the parabola formed by the reflection surface140a. The rotation axis u is parallel to the z-axis inFIG.3. The equation of the parabola is expressed by the following equation (1) when the coordinate of the vertex of the parabola is P(0, 0) and the coordinate of the focal point is F(a, 0).
[Math. 1]
y2=4ax(1)

Due to the mathematical nature of the parabola, when light emitted from the sensor unit130is reflected by the reflection surface140a, the direction of emission of the reflection light is parallel to the axis of the parabola regardless of the angle of the emission light. That is, as illustrated inFIG.3, in the optical path L1and the optical path L2having different emission angles from the sensor unit130, reflected light by the reflection surface140ais parallel to each other. In this manner, by arranging the sensor unit130at the focal point of the reflection surface140a, parallel scan in which the optical path is moved in parallel in the y-axis direction in accordance with the rotation of the emission light can be performed.

The material of the parabolic reflection mirror140may be, for example, an aluminum alloy mainly composed of aluminum. In this case, the reflection surface140amay be formed, for example, by smoothing the surface of an aluminum alloy by mirror polishing or plating. Noted that, other parabolic reflection mirrors described later may be formed of the same material and method.

The plane reflection mirror160is a reflection mirror having a reflection surface160aat least partially forming a plane. The reflection surface160ais provided on the optical path of the reflection light on the reflection surface140a. As illustrated inFIG.3andFIG.4, the plane reflection mirror160changes a direction of the light reflected by the reflection surface140ato a direction different from that in the xy plane. More specifically, the light reflected by the plane reflection mirror160is almost in the z-axis direction, that is, in a direction almost parallel to the rotation axis u. The light reflected by the plane reflection mirror160is emitted to the outside of the ranging device. Thus, the direction of the light emitted from the ranging device100is not limited to the direction parallel to the axis of the reflection surface140a.

The material of the plane reflection mirror160may also be, for example, an aluminum alloy mainly composed of aluminum, as the parabolic reflection mirror140. In this case, the reflection surface160aof the plane reflection mirror160may be formed by the same smoothing as the reflection surface140a, or may be formed by sticking a plate of an aluminum alloy having a specular gloss to a base member. Noted that, other plane reflection mirrors described later may be formed of the same material and method.

A more detailed configuration of the reflection surface140aand160awill be described later.

Here, the lid body120is configured so as not to absorb, reflect, or the like reflection light from the plane reflection mirror160. Specifically, for example, a region of the lid body120through which reflected light from the plane reflection mirror160passes may be formed of a material having transparency. Example of a material having transparency includes acrylic resins. Alternatively, a window may be provided in the lid body120so as to form a cavity in a region through which reflected light from the plane reflection mirror160passes.

The mounting portion170is a part for mounting and fixing the ranging device100to an article display shelf or the like. By being fixed by the mounting portion170, the ranging device100can be mounted in any direction. The position adjustment mechanism150is a mechanism for finely adjusting the position of the plane reflection mirror160when the ranging device100is mounted to an article display shelf or the like. Note that, instead of the position adjustment mechanism150, a drive mechanism for moving the plane reflection mirror160may be provided.

The optical paths L1and L2illustrated inFIG.3andFIG.4illustrate optical paths when light is emitted from the sensor unit130to the outside. On the other hand, the light reflected by the object10and incident on the ranging device100passes in the reverse direction along almost the same path as the optical paths L1and L2and is received by the sensor unit130.

The ranging device100of the present example embodiment has a structure that is thick in the axial direction of the parabolic reflection mirror140due to the thickness of the parabolic reflection mirror140, restrictions on the arrangement position of the sensor unit130, or the like. On the other hand, the ranging device100of the present example embodiment includes the plane reflection mirror160for reflecting the light reflected by the parabolic reflection mirror140. The plane reflection mirror160can change a direction of the emission light from the ranging device100to a direction different from the direction of the axis of the parabola formed by the parabolic reflection mirror. Therefore, in the ranging device100of the present example embodiment, since the light emission direction can be made different from the axial direction of the parabolic reflection mirror140, the thickness in the light emission direction can be reduced. Thus, the ranging device100of the present example embodiment can be easily installed in a narrow place such as between article display shelves. Therefore, according to the present example embodiment, the ranging device100is provided in which the degree of freedom of the installation location is improved.

In the ranging device100of the present example embodiment, the reflection surface140aof the parabolic reflection mirror140is provided so as to exclude the vertex of the parabola. The reason for this configuration will be described with reference toFIGS.5to7.

FIG.5is an optical path diagram in the case where the reflection surface140bis provided at the vertex P of the parabola. For simplicity of explanation, the sensor unit130is simply illustrated as a point light source arranged at the focal point F of the reflection surface140b. If the light emitted from the focal point F is not parallel to the axis of the parabola (if not oriented to vertex P), the reflection light does not pass through the focal point F. However, if the light emitted from the focal point F is parallel to the axis of the parabola (direction towards vertex P) and is reflected at the vertex P, the reflection light passes through the focal point F. Therefore, the light emitted from the sensor unit130is re-incident on the sensor unit130. In this case, when the sensor unit130receives reflection light different from the reflection light from the object10, noise may be generated for the measured signal. As described above, when the reflection surface140bis provided at the vertex P of the parabola, the detection accuracy may be lowered, and sufficient detection accuracy may not be secured.

In contrast, in the ranging device100of the present example embodiment, as illustrated inFIG.6, the reflection surface140ais provided so as to exclude the vertex P of the parabola. Therefore, even if the light emitted from the focal point F is parallel to the axis of the parabola, it is not reflected. Therefore, since the reflection light does not re-enter the sensor unit130, the reduction of the detection accuracy can be suppressed. As described above, according to the present example embodiment, since the reflection surface140aof the parabolic reflection mirror140is provided so as to exclude the vertex of the parabola, the ranging device100having improved detection accuracy is provided.

Note that, inFIG.6, the reflection surface140ais arranged on one side of the axis of the parabola, but as in the modification illustrated inFIG.7, the reflection surface140cmay be arranged on both sides except for the vertex P of the parabola. A specific configuration example corresponding to this modification will be described later.

With reference toFIG.8andFIG.9, a more specific configuration example of the reflection surface140aand160awill be described.FIG.8is a schematic diagram illustrating a configuration example of the reflection surface140a, andFIG.9is a schematic diagram illustrating a configuration example of the reflection surface160a. Note that, the same configuration as that of the reflection surface140aofFIG.8can be applied to the reflection surface140billustrated inFIG.5and the reflection surface140cillustrated inFIG.7.

FIG.8is a diagram of the reflection surface140aviewed from the negative direction of the x-axis. The reflection surface140aincludes a first part R1and a second part R2. The reflectance of the light of the second part R2is less than that of the light of the first part R1. In other words, the light absorptance of the second part R2is greater than that of the first part R1. Note that, in the case where the reflectance of the reflection surface140ashows wavelength dependence, the “reflectance” here means the reflectance at the wavelength of light emitted from and detected by the sensor unit130, that is, light used for sensing. The same applies to the absorptance. For example, when the laser beam emitted from the sensor unit130is an infrared ray having a wavelength of 905 nm, the above-described “reflectance” is assumed to be a reflectance with respect to an infrared ray having a wavelength of 905 nm.

The light emitted from the sensor unit130and the light detected by the sensor unit130pass through the same optical path in the opposite direction. Therefore, structures outside the optical path, such as outside the scan range in the reflection surface140a, ideally do not affect detection accuracy. However, the light flux emitted from the sensor unit130has a certain width, and light may leak out of the scan range. Further, since the reflection light from the parabolic reflection mirror140or the like includes an element of diffused reflection in addition to the specular reflection, the light diffusely reflected outside the scan range may be incident on the sensor unit130. Thus, in reality, stray light as noise may be generated by reflection outside the assumed optical path. Such stray light may affect the detection accuracy. The reflection surface140aofFIG.8includes a second part R2having low light reflectance. By arranging the second part R2at an appropriate position, it is possible to attenuate an element of the light reflected by the reflection surface140awhich may affect the detection accuracy, and the detection accuracy can be improved.

It is desirable that the first part R1is within a range where light is incident when the sensor unit130rotates and scans the emission light, and the second part R2is within a range where light is not incident when the sensor unit130rotates and scans the emission light. When the sensor unit130rotates and scans the emission light, the light reflected at the second part R2on the reflection surface140abecomes stray light. When such light is incident on the sensor unit130, it becomes noise, so it is desirable to lower the reflectance of light from outside the scan range.

As illustrated inFIG.8, it is also desirable that the second part R2is arranged surrounding the first part R1. This is because it is desirable to provide the second part R2having low reflectance of light around the first part R1since the reflection causing stray light is likely to occur around the scan range.

Next, a specific method of forming the first part R1and the second part R2will be described. When the entire parabolic reflection mirror140is made of a base member such as an aluminum alloy, the first part R1and the second part R2are made of the same base member. In this case, the surface of the base member of the second part R2has a surface treated to reduce reflectance so that the reflectance of the second part R2can be made lower than that of the first part.

As a specific example of a treatment for reducing the reflectance, a treatment for covering the surface of the second part R2with a light absorbing material by applying a coating material having light absorbing properties, sticking a light absorbing film or the like, forming a light absorbing thin film (for example, deposition or plating) or the like can be applied. In addition, the surfaces of the first part R1and the second part R2may be covered with different materials using the above-described method. By using such a manufacturing method, the parabolic reflection mirror140can be manufactured more easily than when the first part R1and the second part R2are made of different base member.

As another example of the treatment of covering with the light absorbing material, the surface of the reflection surface140amay be oxidized by anodic oxidation to form the light absorbing material. Alternatively, the surface of the second part R2may be polished with a coarser abrasive material than the first part R1, and the surface roughness of the second part R2may be made greater than that of the first part R1to reduce the reflectance. According to these manufacturing methods, the parabolic reflection mirror140can be easily manufactured without separately supplying the light absorbing material.

However, different base members may be combined to form the first part R1and the second part R2. In this case, a material having less reflectance than that of the base member of the first part is used as the base member of the second part R2. For example, by using a metal such as an aluminum alloy as the base member of the first part R1and a resin or the like as the base member of the second part R2, the parabolic reflection mirror140can be made lightweight.

The reflection surface160aillustrated inFIG.9includes the same configuration as the reflection surface140aand exhibits the same effect.

As described above, according to the configuration of the reflection surface140aand160aillustrated inFIG.8andFIG.9of the present example embodiment, noise caused by stray light is reduced, and the ranging device100with improved detection accuracy is provided.

Note that, even if either one of the reflection surface140aand160aincludes the first part R1and the second part R2, an effect of improving detection accuracy can be obtained. However, it is desirable that both the reflection surface140aand160ainclude the first part R1and the second part R2, because a higher effect can be obtained.

Second Example Embodiment

Next, as a second example embodiment of the present invention, a configuration example of a ranging device capable of translating a plane reflection mirror will be described. The description of components common to the above-described example embodiment is omitted or simplified.

FIG.10is a schematic diagram illustrating a structure of a ranging device101of the present example embodiment as viewed from the top. The ranging device101of the present example embodiment is provided with a drive mechanism151instead of a position adjustment mechanism150, and a plane reflection mirror161instead of a plane reflection mirror160. The drive mechanism151drives the plane reflection mirror161to move parallel to the axial direction of the parabolic reflection mirror140(x-axis direction inFIG.10). The drive mechanism151includes a drive device such as a motor. The drive mechanism151also includes a device for acquiring position information of the plane reflection mirror161such as an encoder. These devices are controlled by a control device200. The position information of the plane reflection mirror161acquired by the drive mechanism151is supplied to the control device200.

When the drive mechanism151drives the plane reflection mirror161to move parallel to the x-axis direction, the reflection light by the plane reflection mirror161also moves parallel to the x-axis direction. Thus, the ranging device101of the present example embodiment is capable of scanning to translate the reflection light by the plane reflection mirror161in the x-axis direction. As in the first example embodiment, the ranging device101of the present example embodiment is also capable of scanning to translate the reflection light by the plane reflection mirror161in the y-axis direction. Therefore, the ranging device101of the present example embodiment functions as a three-dimensional sensor device capable of acquiring three-dimensional position information by combining two-dimensional scan in the x-axis direction and the y-axis direction and distance measurement in the z-axis direction, in addition to obtaining the same effect as that of the first example embodiment.

Noted that, the parabolic reflection mirror140and the plane reflection mirror161of the present example embodiment may also have reflection surface including the first part R1and the second part R2as in the first example embodiment. In this case, the same effects as those described in the first example embodiment can be obtained. Accordingly, the ranging device101with improved detection accuracy is provided.

Third Example Embodiment

Next, as a third example embodiment of the present invention, a configuration example of a ranging device capable of rotating and moving a plane reflection mirror will be described. The description of components common to the first example embodiment is omitted or simplified.

FIG.11is a schematic diagram illustrating a structure of a ranging device102of the present example embodiment as viewed from the top. The ranging device102of the present example embodiment is provided with a drive mechanism152instead of a position adjustment mechanism150, and a plane reflection mirror162instead of a plane reflection mirror160. The drive mechanism152drives the plane reflection mirror162to rotate about a rotation axis v parallel to the y-axis. The position of the rotation axis v may be a position where the direction of the reflection light from the plane reflection mirror162changes according to the rotation, and may be, for example, on a path through which the reflection light from the parabolic reflection mirror140passes. The drive mechanism152includes a drive device such as a motor. The drive mechanism152also includes a device for acquiring angle information of the plane reflection mirror162such as an encoder. These devices are controlled by a control device200. The angle information of the plane reflection mirror162acquired by the drive mechanism152is supplied to the control device200.

When the drive mechanism152drives the plane reflection mirror162and the plane reflection mirror162rotates, the direction of the reflection light from the plane reflection mirror162also rotates. Thus, the ranging device102of the present example embodiment can perform a scan to rotate and move the direction of the reflection light from the plane reflection mirror162. As those described in the first example embodiment, the ranging device102of the present example embodiment is also capable of scanning the plane reflection mirror162so as to translate the reflection light in the y-axis direction. Therefore, the ranging device102of the present example embodiment functions as a three-dimensional sensor device capable of acquiring three-dimensional position information by combining rotational movement on the rotational axis v, parallel movement in the y-axis direction, and distance measurement, in addition to obtaining the same effect as in the first example embodiment.

Noted that, the parabolic reflection mirror140and the plane reflection mirror162of the present example embodiment may also have reflection surfaces including the first part R1and the second part R2as in the first example embodiment. In this case, the same effects as those described in the first example embodiment can be obtained. Accordingly, the ranging device102with improved detection accuracy is provided.

Fourth Example Embodiment

Next, as a fourth example embodiment of the present invention, a configuration example of a ranging device further including a logarithmic spiral reflection mirror will be described. The description of components common to the above-described example embodiments is omitted or simplified.

FIG.12is a schematic perspective view illustrating a structure of a ranging device300according to the fourth example embodiment.FIG.13is a schematic view illustrating the structure of the ranging device300as viewed from the top. The structure of the ranging device300will be described with reference to these figures. Note that, inFIG.12andFIG.13, components that are not necessary for the description of an optical path, such as the base body110, the lid body120, and the mounting portion170, may be omitted.

The ranging device300includes a sensor unit130, a parabolic reflection mirror340, a drive mechanism351, a logarithmic spiral reflection mirror361, and plane reflection mirrors362,363,364, and365. The parabolic reflection mirror340has reflection surfaces340aand340b. The reflection surfaces340aand340bform parabolas, in a section perpendicular to the rotation axis u (xy plane inFIG.12), focusing on a point on the rotation axis u. The reflection surfaces340aand340bare perpendicular to each other in the xz plane as illustrated inFIG.13.

Light emitted from the sensor unit130in the negative direction of the x-axis is reflected in the z-axis direction by the reflection surface340a, and then reflected in the positive direction of the x-axis toward the logarithmic spiral reflection mirror361by the reflection surface340b. By causing the reflection surfaces340aand340bto reflect twice to shift the optical path in the z direction, the reflection light from the parabolic reflection mirror340can be prevented from being inhibited by the sensor unit130. Further, since the reflection light does not re-enter the sensor unit130, the detection accuracy can be improved for the same reason as that described with reference toFIGS.5to7.

The logarithmic spiral reflection mirror361has a columnar shape, and has a reflection surface361aforming a logarithmic spiral on the side faces thereof. The light emitted from the sensor unit130is reflected by the reflection surface361a. The logarithmic spiral reflection mirror361is rotatable about a rotation axis w by the drive mechanism351. At this time, the light reflected by the reflection surface361amoves in parallel according to the angle of the logarithmic spiral reflection mirror361.

With reference toFIG.14andFIG.15, a more specific structure of the logarithmic spiral reflection mirror361will be described.FIG.14is a sectional view of the logarithmic spiral reflection mirror361according to the present example embodiment in a plane perpendicular to the rotation axis w. The reflection surface361athat is the side face of the logarithmic spiral reflection mirror361forms a closed curve in which four logarithmic spirals are continuously connected in a cross section perpendicular to the rotation axis w. With a closed curve in which logarithmic spirals are continuously connected as described above, a configuration in which the entire reflection surface361athat light emitted from the sensor unit130may enter forms a logarithmic spiral in a cross section perpendicular to the rotation axis w is realized. Accordingly, even when light enters any of the surfaces of the logarithmic spiral reflection mirror361, it is possible to utilize reflected light for a scan. Note that, a logarithmic spiral may be referred to as an equiangular spiral or a Bernoulli's spiral.

FIG.15is a diagram illustrating reflection of light by a reflection surface forming a logarithmic spiral. The logarithmic spiral Sp is expressed by a polar equation of the following Equation (2):
[Math. 2]
r=a·exp(θ·cotb)  (2)
where r denotes the radial coordinate in the polar coordinate, θ denotes the angular coordinate in the polar coordinate, a denotes the value of r when the value of θ is zero, and b denotes the angle of a line passing through the center of the logarithmic spiral relative to a tangent line of the logarithmic spiral.

Herein, the relationship between the incident light I11and I21from the outside of the logarithmic spiral Sp toward the origin O of the polar equation of Equation (2) and the reflected light I12and I22thereof is considered. The tangent line and the normal line at a point at which the incident light I11is reflected by the logarithmic spiral Sp are defined as t1and S1, respectively, and the tangent line and the normal line at a point at which the incident light I21is reflected by the logarithmic spiral Sp are defined as t2and S2, respectively. It is assumed that the incident light I11is reflected at a point of the radial coordinate r1on the logarithmic spiral Sp, and the incident light I21is reflected at a point of the radial coordinate r2on the logarithmic spiral Sp (where r1≠r2). In this example, due to a nature of the logarithmic spiral Sp, both of the angle of the incident light I11relative to the tangent line t1and the angle of the incident light I21relative to the tangent line t2are b. Therefore, the incident angle φ of the incident light I11relative to the normal line S1and the incident angle φ of the incident light I21relative to the normal line S2are the same angle. Also, the reflection angle φ of the reflected light I12relative to the normal line S1and the reflection angle φ of the reflected light I22relative to the normal line S2are the same angle. When φ and b are angles expressed in the circular measure, the relationship between φ and b is as expressed by the following Equation (3).

[Math.⁢3]ϕ=π2-b(3)

From the above discussion, it is found that the incident light I11from the outside of the logarithmic spiral Sp toward the origin O is reflected at the same reflection angle φ even when reflected at any point on the logarithmic spiral Sp. Thus, when the logarithmic spiral Sp is rotated on the origin O, the point at which the incident light I11to the logarithmic spiral Sp is reflected changes, but the direction in which the reflected light I12is reflected does not change, and therefore the reflected light I12moves in parallel.

In the logarithmic spiral reflection mirror361of the present example embodiment, to utilize the above nature, at least a part of a reflection surface forms a logarithmic spiral in which the rotation axis w matches the origin O in a cross section perpendicular to the rotation axis w. Accordingly, rotation of the logarithmic spiral reflection mirror361on the rotation axis w enables a scan so that the light reflected by the reflection surface361amoves in parallel.

Returning again toFIG.13, the parallel scan by the reflection light by the logarithmic spiral reflection mirror361will be described. The light reflected by the logarithmic spiral reflection mirror361is made incident and reflected on either the plane reflection mirror362or the plane reflection mirror364according to the angle of the logarithmic spiral reflection mirror361. The light reflected by the plane reflection mirror362is reflected by the plane reflection mirror363and emitted to the outside of the ranging device300. The light emission direction at this time is a positive direction of the z-axis. The light reflected by the plane reflection mirror364is reflected by the plane reflection mirror365and emitted to the outside of the ranging device300. The light emission direction at this time is a negative direction of the z-axis.

When the logarithmic spiral reflection mirror361rotates clockwise as illustrated inFIG.13, the light emitted from the ranging device300moves in parallel from the optical path L5toward the optical path L6. When the logarithmic spiral reflection mirror361further rotates while the emission light is in the optical path L6, the emission light changes discontinuously from the optical path L6to the optical path L7. Thereafter, the emission light moves in parallel from the optical path L7toward the optical path L8, and changes discontinuously from the optical path L8to the optical path L5. As described above, the ranging device300of the present example embodiment can alternately scan the positive direction and the negative direction of the z-axis.

Thus, ranging device300of the present example embodiment is capable of scanning to translate the emission light in the x-axis direction. As in the case of the first example embodiment, the ranging device300of the present example embodiment is also capable of scanning to move the emission light in parallel in the y-axis direction. Therefore, the ranging device300of the present example embodiment functions as a three-dimensional sensor device capable of acquiring three-dimensional position information by combining two-dimensional scan in the x-axis direction and the y-axis direction and distance measurement in the z-axis direction, in addition to obtaining the same effect as that of the first example embodiment. Further, since the ranging device300of the present example embodiment can alternately scan the positive direction and the negative direction of the z-axis, distance measurement in two different directions can be performed by one ranging device300.

With reference toFIG.16,FIG.17, andFIG.18, a more specific configuration example of the reflection surface of each reflection mirror will be described.FIG.16is a schematic view illustrating a configuration example of the reflection surfaces340aand340bof the parabolic reflection mirror340,FIG.17is a schematic view illustrating a configuration example of the reflection surface361aof the logarithmic spiral reflection mirror361, andFIG.18is a schematic view illustrating a configuration example of the reflection surface362aof the plane reflection mirror362. The same configuration as that of the reflection surface362aofFIG.18may be applied to the reflection surface of the plane reflection mirrors363,364and365illustrated inFIG.12.

As illustrated inFIG.16, the reflection surfaces340aand340binclude a first part R1and a second part R2, respectively. In each of the reflection surfaces340aand340b, the second part R2is arranged surrounding the first part R1.

As illustrated inFIG.17, the reflection surface361aincludes a first part R1and a second part R2. The second part R2is arranged above and below the first part R1.

As illustrated inFIG.18, the reflection surface362aincludes a first part R1and a second part R2. The second part R2is arranged surrounding the first part R1.

As in the first example embodiment, the reflectance of light of the second part R2is less than that of the first part. The reflection surfaces340a,340b,361a, and362aof the first part R1and the second part R2are formed by a manufacturing method as that described in the first example embodiment.

Also in the present example embodiment, noise caused by stray light is reduced for the same reason as that described in the first example embodiment. Thus, the ranging device300with improved detection accuracy is provided.

Fifth Example Embodiment

Next, as a fifth example embodiment of the present invention, a configuration example of a ranging device including two optical systems will be described. The description of components common to the above-described example embodiments is omitted or simplified.

FIG.19is a schematic view illustrating a structure of a ranging device400according to a fifth example embodiment as viewed from the front.FIG.20is a schematic view illustrating the structure of the ranging device400as viewed from the top. The structure of the ranging device400will be described with reference to these figures.

The ranging device400includes a first optical system401and a second optical system402. The first optical system401includes a sensor unit130, a parabolic reflection mirror140, and a plane reflection mirror160. Since the first optical system401is the same as the ranging device100of the first example embodiment, the description thereof is omitted. Note that, the top view of the first optical system401is the same as that ofFIG.4.

The second optical system402includes a parabolic reflection mirror440and a plane reflection mirror460. The parabolic reflection mirror440has reflection surface440a. The reflection surface440aforms a parabola with a point on the rotation axis u as a focal point in a section perpendicular to the rotation axis u (xy plane inFIG.19). The parabolic reflection mirror440has a line-symmetric structure with the parabolic reflection mirror140. The plane reflection mirror460has a line-symmetric structure with the plane reflection mirror160. The parabolic reflection mirror140and the parabolic reflection mirror440are arranged at positions symmetrical to the axis of the parabola. The plane reflection mirror160and the plane reflection mirror460are arranged at positions symmetrical to the axis of the parabola. Note that, the structure of a housing for storing the components of the second optical system402may be, for example, a housing illustrated inFIG.2of the first example embodiment reversed in the y direction.

When light is emitted from the sensor unit130in the lower left direction in the figure, it is incident on the reflection surface440a. The light reflected by the reflection surface440abecomes parallel to the axis of the parabola like the optical paths L9and L10. The light reflected by the reflection surface440a, as illustrated inFIG.20, is emitted to the outside of the second optical system402.

The reflection surface140aof the parabolic reflection mirror140and the reflection surface440aof the parabolic reflection mirror440are provided so as to exclude the vertex of the parabola. This configuration corresponds to the optical path diagram illustrated inFIG.7. Thus, as described with reference toFIGS.5to7, since the reflection light at the vertex of the parabola is not re-incident on the sensor unit130, the reduction of the detection accuracy can be suppressed. Therefore, in the present example embodiment as well as in the first example embodiment, it is possible to provide the ranging device400with improved detection accuracy. Further, in the present example embodiment, the scan range of the emission light can be widened by using two optical systems.

Noted that, the parabolic reflection mirror140and440and the plane reflection mirror160and460of the present example embodiment may also have reflection surfaces including the first part R1and the second part R2as in the first example embodiment. In this case, the same effects as those described in the first example embodiment can be obtained. Accordingly, the ranging device400with improved detection accuracy is provided.

Sixth Example Embodiment

Next, as a sixth example embodiment of the present invention, a configuration example of a ranging device including a logarithmic spiral reflection mirror and two parabolic reflection mirrors will be described. The description of components common to the above-described example embodiments is omitted or simplified.

FIG.21is a schematic diagram illustrating a structure of a ranging device301according to a sixth example embodiment as viewed from an angle.FIG.22is a schematic view illustrating the structure of the ranging device301as viewed from the top. The ranging device301of the present example embodiment is a ranging device that the parabolic reflection mirror340of the ranging device300of the fourth example embodiment is replaced with the parabolic reflection mirror140and parabolic reflection mirror440of the fifth example embodiment. In the present example embodiment, the same effects as in the fourth example embodiment can be obtained. In the present example embodiment, the structure of the parabolic reflection mirror is simplified as compared with the fourth example embodiment.

Note that, the parabolic reflection mirrors140and440, the logarithmic spiral reflection mirror361and the plane reflection mirrors362,363,364and365of the present example embodiment may also include reflection surface including the first part R1and the second part R2as in the fourth example embodiment. In this case, the same effects as those described in the fourth example embodiment can be obtained. Accordingly, the ranging device301with improved detection accuracy is provided.

Seventh Example Embodiment

Next, as a seventh example embodiment of the present invention, a configuration example of an article display shelf including a ranging device400in the fifth example embodiment will be described. The description of components common to the above-described example embodiments is omitted or simplified.

FIG.23is a schematic perspective view of an article display shelf500according to a seventh example embodiment.FIG.24is a schematic side view of the article display shelf500. The structure of the article display shelf500will be described with reference to these figures.

The article display shelf500is a shelf for displaying articles540and may be, for example, a goods display shelf installed in a commercial facility. The article display shelf500includes a shelf510and two ranging devices400. The two ranging devices400are arranged on the side surface of the shelf510. The shelf510is provided with four display portions520divided by display plates530. In the display portion520, articles540such as goods are displayed. The display portion520includes an opening portion570for taking in and out the article540. The number of the ranging device400and the display portion520is not limited to those illustrated in the diagrams, and may be plural or single.

The ranging device400includes the first optical system401and the second optical system402described in the fifth example embodiment. Light that passes through the first optical system401or the second optical system402and emits in the positive direction of the z-axis passes across the front of the opening portion570of the display portion520. As a result, in front of the opening portion570of the display portion520, a detection region550by the ranging device400is formed. When the customer560takes out the article540from the display portion520or returns the taken out article540to the display portion520, the article540and the hand of the customer560pass through the detection region550. The ranging device400detects the article540or the hand of the customer560passing through the detection region550to detect the taking in and out of the article540. When a plurality of articles540may be arranged in the display portion520, the ranging device400may detect the position where the article540has been taken in and out or the shape of the article540which has been taken in and out to specify the article540which has been taken in and out.

The article display shelf500of the present example embodiment is provided with the ranging device400, so that it is possible to detect the taking in and out of the articles540on display. This function may be used, for example, for the management of goods and the prevention of theft. Further, as described above, since the ranging device400has a small thickness in the light emission direction, it is possible to install it in a narrow space on the side surface of the article display shelf500. Thus, the size of the whole article display shelf500can be reduced.

Although it is not essential, as illustrated inFIG.23, it is desirable that the position of the shelf plate530in the y-axis direction is between the first optical system401and the second optical system402. In the ranging device400according to the fifth example embodiment, an insensitive area is formed between the first optical system401and the second optical system402, but the insensitive area can be substantially narrowed by arranging the shelf plate530in the insensitive area.

In other words, the configuration that the shelf plate530is arranged in the above-described insensitive area can be described as follows. InFIG.23, the display portions520at the first and third stages from the top are called the first display portion, and the display portions520at the second and fourth stages from the top are called the second display portion. The opening portion570corresponding to the first display portion is called a first opening portion, and the opening portion570corresponding to the second display portion is called a second opening portion. At this time, as illustrated inFIG.23, the light emitted from the first optical system401is arranged so as to cross the front of the first opening portion, and the light emitted from the second optical system402is arranged so as to cross the front of the second opening portion. In this case, the first display portion and the second display portion are separated from each other by the shelf plate530, and the position of the shelf plate530corresponds to the insensitive area between the first optical system401and the second optical system402.

Note that, the ranging device400of the fifth example embodiment has been described as an example of the ranging device installed on the article display shelf500of the present example embodiment, the ranging device of other example embodiments may be used.

For the article display shelf500, it is more desirable to use the ranging device including the reflection surfaces of the first part R1and the second part R2described in the first to the sixth example embodiments, and in this case, the detection accuracy of taking in and out of the article540is further improved.

Eighth Example Embodiment

Next, as an eighth example embodiment of the present invention, a configuration example of an article display shelf that the arrangement of the ranging device is changed with respect to the seventh example embodiment will be described. The description of components common to the above-described example embodiments is omitted or simplified.

FIG.25is a schematic front view of an article display shelf501according to the eighth example embodiment. The article display shelf501of the present example embodiment includes a shelf511and four ranging devices400a,400b,400c, and400darranged around the shelf511. In the article display shelf501of the present example embodiment, the arrangement of the ranging device is different from that in the seventh example embodiment. The ranging device400ais arranged on the left side surface of the shelf511. The ranging device400bis arranged on the right side surface of the shelf511. The ranging device400cis arranged on the upper surface of the shelf511. The ranging device400dis arranged on the lower surface of the shelf511. Light emitted from each ranging device400passes across the front of the display portion520. As a result, a detection region is formed in front of the opening portion571of the display portion521by the ranging device400, and the ranging device400can detect the taking in and out of the article540.

In the present example embodiment, the ranging device400a(first sensor device) emits light in a first direction which is a positive direction of the z-axis, and the ranging device400b(second sensor device) emits light in a second direction which is a negative direction of the z-axis. That is, the ranging device400aand the ranging device400bemit light parallel to each other and in opposite directions. Similarly, the ranging device400cand the ranging device400demit light parallel to each other and in opposite directions. Thus, even when a plurality of customers560simultaneously take in and out the articles540, the light is hardly blocked by the articles540or the like, and the detection accuracy is improved.

Further, since the ranging devices400aand400b(first sensor device) emit light in the first direction which is the z-axis direction, and the ranging devices400cand400d(second sensor device) emit light in the second direction which is the y-axis direction, the light emission directions are perpendicular to each other. Thus, the position where the customer560takes the article540in and out can be detected from two directions, and the detection accuracy is further improved.

For the article display shelf501, it is more desirable to use the ranging device including the reflection surfaces of the first part R1and the second part R2described in the first to the sixth example embodiments, and in this case, the detection accuracy of taking in and out of the article540is further improved.

Ninth Example Embodiment

Next, as a ninth example embodiment of the present invention, a configuration example of an article display shelf which the arrangement of the ranging device is changed with respect to the seventh example embodiment will be described. The description of components common to the above-described example embodiments is omitted or simplified.

FIG.26is a schematic side view of an article display shelf502according to the ninth example embodiment. In the article display shelf502of the present example embodiment, the shape of the shelf511and the arrangement of the second optical system402are different from those of the seventh example embodiment. In the shelf511of the present example embodiment, the lowermost shelf plate531protrudes toward the customer. In order to correspond with this, the second optical system402provided at the lowermost stage is provided at an angle θ with respect to the first optical system401at the upper stage. Thus, the detection region551formed by the second optical system402provided in the lowermost stage has an angle θ with respect to the detection region550formed by the first optical system401in the upper stage. Thus, the detection region can be arranged at a proper position even for shelves having different widths of the shelf boards for each stage. When the second optical system402is inclined, by rotating the second optical system402around the rotation axis u of the sensor unit130in the first optical system401, the detection region can be inclined while maintaining the optical arrangement capable of parallel scan.

Note that, the range of the angle θ is set to be greater than 160 degrees and less than 180 degrees, for example. Since the first optical system401and the second optical system402are longitudinally elongated in the x direction, members may interfere with each other when the angle θ becomes 160 degrees or less.

For the article display shelf502, it is more desirable to use the ranging device including the reflection surfaces of the first part R1and the second part R2described in the first to the sixth example embodiments, and in this case, the detection accuracy of taking in and out of the article540is further improved.

Tenth Example Embodiment

Next, as a tenth example embodiment of the present invention, a configuration example of an article display shelf including a ranging device301according to the sixth example embodiment will be described. The description of components common to the above-described example embodiments is omitted or simplified.

FIG.27is a schematic perspective view of an article display shelf503according to a tenth example embodiment. The article display shelf503of the present example embodiment includes shelves510and512, and two ranging devices301. The two ranging devices301are arranged between the side surfaces of the shelf510and the side surfaces of the shelf512. Since the ranging device301according to the sixth example embodiment can emit light in two directions to form a detection region, the ranging device301can detect both the left and right shelves510and512for taking in and out of the article540. As a result, for example, the number of ranging devices can be reduced as compared with the case where the ranging devices400of the fifth example embodiment are installed. Note that, the ranging device used for the article display shelf503of the present example embodiment may be the ranging device300of the fourth example embodiment.

For the article display shelf503, it is more desirable to use the ranging device including the reflection surfaces of the first part R1and the second part R2described in the fourth or the sixth example embodiments, and in this case, the detection accuracy of taking in and out of the article540is further improved.

The device described in the above example embodiments can be configured as in the following eleventh example embodiment.

Eleventh Example Embodiment

FIG.28is a block diagram of a sensor device600according to an eleventh example embodiment. The sensor device600includes a sensor unit630and a reflection mirror unit640. The sensor unit630emits light and receives the light reflected from the object. The reflection mirror unit640reflects light emitted from the sensor unit630. The reflection surface of the reflection mirror included in the reflection mirror unit640includes a first part and a second part having a lower reflectance than the first part.

According to the present example embodiment, a sensor device600having improved detection accuracy is provided.

MODIFIED EXAMPLE EMBODIMENTS

Note that all of the example embodiments described above are mere embodied examples in implementing the present invention, and the technical scope of the present invention should not be construed in a limiting sense by these example embodiments. That is, the present invention can be implemented in various forms without departing from the technical concept or the primary feature thereof. For example, examples in which a part of the configuration of one example embodiment is added to another example embodiment, or examples in which a part of the configuration of another example embodiment is replaced are also example embodiments of the present invention.

The whole or part of the example embodiments disclosed above can be described as, but not limited to, the following supplementary notes.

(Supplementary Note 1)

A sensor device comprising:a sensor unit that emits light and receives light reflected by an object; anda reflection mirror unit that reflects light emitted from the sensor unit,wherein a reflection surface of a reflection mirror included in the reflection mirror unit includes a first part and a second part having lower reflectance than the first part.
(Supplementary Note 2)

The sensor device according to supplementary note 1,wherein the sensor unit or the reflection mirror unit is configured to perform a scan by changing an optical path of light,wherein the first part is, within a range of the scan, a range in which light emitted from the sensor unit is incident, andwherein the second part is, within a range of the scan, a range in which light emitted from the sensor unit is not incident.
(Supplementary Note 3)

The sensor device according to supplementary note 1 or 2, wherein the second part is arranged surrounding the first part.

(Supplementary Note 4)

The sensor device according to any one of supplementary notes 1 to 3,wherein the first part and the second part are made of a same base member, andwherein the base member at the second part has a surface treated to reduce reflectance.
(Supplementary Note 5)

The sensor device according to supplementary note 4, wherein a surface of the base member at the second part is covered with a light absorbing material.

(Supplementary Note 6)

The sensor device according to supplementary note 4, wherein surface roughness of the base member at the second part is greater than that of the base member at the first part.

(Supplementary Note 7)

The sensor device according to any one of supplementary notes 1 to 3,wherein the first part and the second part are made of different base members, andwherein reflectance of a base member of the second part is less than that of a base member of the first part.
(Supplementary Note 8)

The sensor device according to any one of supplementary notes 1 to 7,wherein the reflection mirror unit includes a plurality of the reflection mirrors, andwherein each reflection surface of the plurality of the reflection mirrors includes the first part and the second part.
(Supplementary Note 9)

The sensor device according to any one of supplementary notes 1 to 8, wherein the sensor unit is a Light Detection and Ranging (LiDAR) device that acquires distance information based on light reflected by the object.

(Supplementary Note 10)

An article display shelf comprising:the sensor device according to any one of supplementary notes 1 to 9; anda display portion on which an article is displayed.

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2018-202825, filed on Oct. 29, 2018, the disclosure of which is incorporated herein in its entirety by reference.

REFERENCE SIGNS LIST

10object100-102,300-301,400,400a-400dranging device110base body120lid body130sensor unit140,340,440parabolic reflection mirror140a-140c,160a,340a-340b,361a,362a,440areflection surface150position adjustment mechanism151-152,351drive mechanism160-162,362-365,460plane reflection mirror170mounting portion200control device210interface220control unit230signal processing unit240storage unit361logarithmic spiral reflection mirror401first optical system402second optical system500-503article display shelf510-512shelf520-521display portion530-531display plate540article550-551detection region560customer570-571opening portion600sensor device630sensor unit640reflection mirror unitR1first partR2second part