Imaging device

Abstract

To suppress the influence of reflected light by a cover in an imaging device.SOLUTION: An imaging device 1 comprises: a first imaging section 101 having a first viewpoint P1 and a second imaging section 102 having a second viewpoint P2 as an imaging section 100; and a transparent cover 2 that is disposed in an area where at least a portion of a first field of view V1 of the first imaging section 101 and a second field of view V2 of the second imaging section 102 cross so as to accommodate the imaging section 100. The cover 2 has a portion having a spheroidal shape as a cover portion having a shape for causing light beams from an area near the first viewpoint P1 to be reflected so as to be directed toward an area near the second viewpoint P2.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to the technology of imaging devices.

Background Art

[0002] For example, in realizing the automatic driving of a vehicle, it is necessary to recognize an object existing in the entire periphery of the host vehicle with an image in a wide field of view and measure the distance to the object. Further, for example, in a security camera (or a surveillance camera) installed on a ceiling or a wall, etc., acquisition of an image in a wide field of view is also required. In order to perform highly reliable person tracking and accurate object dimension measurement within this field of view, not only image acquisition but also distance measurement is required.

[0003] Japanese Patent Application Laid-Open No. 2001-094842 (Patent Document 1) describes that, as a method for preventing indoor reflection in an in-vehicle camera, the polarization axis of the polarizing filter of the camera is offset by an offset angle θ with respect to the vertical so as to prevent the reflection of the upper part of the instrument panel due to reflection inside the windshield and avoid the influence on the recognition performance (abstract).

[0004] Japanese Patent No. 4388530 (Patent Document 2) describes that it includes a first reflection part, a second reflection part, a third reflection part, and an image imaging part, and the second reflection part has a hole in the center, and the light reflected from the first reflection part and the light reflected from the third reflection part pass through the hole at the same time (Claim 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Patent Document 1 describes that when imaging with an in-vehicle stereo camera, the reflection inside the windshield is prevented using a polarizing filter. Patent Document 1 does not describe a specific shape of the windshield, and a separately prepared polarizing filter for the camera must be used.

[0007] Patent Document 2 describes that, for example, three hyperboloids are arranged opposite each other, one camera is arranged inside one of the hyperboloids, and an image from two viewpoints reflected by the three hyperboloids is captured by that one camera. Thereby, a stereo camera is configured, and it is possible to acquire an image and measure distance for 360 degrees all around. Patent Document 2 does not describe the shape of the cover that supports and houses the two hyperboloids. FIG. 7 of Patent Document 2 shows a cylindrical cover in a prototype. However, in the case of a cover of such a shape, the reflected light from the cover is reflected as stray light and appears in the acquired image. When the reflected light appears in the image, the accuracy of image recognition and distance measurement decreases.

[0008] An object of the present invention is to provide a technology capable of suppressing the influence of reflected light by a cover in an imaging device.

Means for Solving the Problems

[0009] A typical embodiment of the present disclosure has the following configuration. The imaging device of the embodiment includes, as an imaging unit, a first imaging unit having a first viewpoint and a second imaging unit having a second viewpoint, and a light-transmissive cover disposed in a region that intersects at least a part of a first field of view of the first imaging unit and a second field of view of the second imaging unit so as to house the first imaging unit and the second imaging unit. The cover has a cover portion shaped to reflect light rays from a vicinity region of the first viewpoint toward a vicinity region of the second viewpoint.

Effect of the Invention

[0010] According to a typical embodiment of the present disclosure, it is possible to suppress the influence of reflected light by a cover in an imaging device. Regarding problems, configurations, effects, etc. other than those described above, they are shown in the mode for carrying out the invention.

Brief Description of the Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same reference numerals are generally given to the same parts, and repeated explanations are omitted. In the drawings, the representation of the components may not represent the actual position, size, shape, and range, etc. for the purpose of facilitating the understanding of the invention.

[0013] For the purpose of explanation, when explaining the processing by a program, the program, function, processing unit, etc. may be mainly explained. However, the main body of them as hardware is a processor, or a controller, device, computer, system, etc. composed of such a processor. The computer executes processing according to the program read onto the memory while appropriately using resources such as a memory and a communication interface by the processor. Thereby, a predetermined function, processing unit, etc. are realized. The processor is composed of a semiconductor device such as a CPU or a GPU, for example. The processor is composed of a device or circuit capable of performing a predetermined operation. The processing is not limited to software program processing and can also be implemented by a dedicated circuit. Applicable dedicated circuits include FPGA, ASIC, CPLD, etc.

[0014] The program may be pre-installed as data in the target computer, or may be distributed as data to the target computer from the program source. The program source may be a program distribution server on a communication network, or a non-transitory computer-readable storage medium (e.g., a memory card). The program may be composed of a plurality of modules. The computer system may be composed of a plurality of devices. The computer system may be composed of a client-server system, a cloud computing system, an IoT system, etc. Various data and information are composed in a structure such as a table or a list, but are not limited thereto. Expressions such as identification information, identifier, ID, name, number, etc. are mutually replaceable.

[0015] <Embodiment 1> Using FIGS. 1 to 5 and the like, the imaging device according to Embodiment 1 of the present disclosure will be described. The imaging device according to Embodiment 1 has a cover 2 as shown in FIG. 3 described later, and the cover 2 has an ellipsoidal surface shape. By this cover 2, reflected light is suppressed, and stray light incident on the imaging unit 100 is reduced.

[0016] [Imaging Device and Processing Device (1)] FIG. 1 shows a functional block configuration example of the imaging device 1 according to Embodiment 1. The imaging device 1 according to Embodiment 1 includes, as an imaging unit 100, a first imaging unit 101 having a first viewpoint and a second imaging unit 102 having a second viewpoint, a cover 2, and a processing device 3. In other words, the imaging unit 100 is a camera, the first imaging unit 101 is the first camera, and the second imaging unit 102 is the second camera. The cover 2 is a light-transmissive member that houses the imaging unit 100 in the space delimited by the cover 2. The imaging unit 100 and the cover 2 are installed on the installation surface 4 (particularly the substrate 40).

[0017] The imaging device 1 of Embodiment 1 particularly has features in the cover 2 of the imaging unit 100. In FIG. 1, only the concepts of the cover 2 and the installation surface 4 are illustrated, and the specific shapes of the cover 2 and the installation surface 4 are shown in FIG. 3 and the like described later. Also, in FIG. 1, the processing device 3 externally connected to the imaging device 1 of Embodiment 1 is also illustrated.

[0018] The imaging device 1 is mounted on a predetermined object, for example, an automobile or an autonomous driving robot. Alternatively, the imaging device 1 is installed on a building wall, ceiling, etc. for applications such as security cameras. The imaging device 1 of Embodiment 1 can be installed on any object. The imaging device 1 of Embodiment 1 can be used, for example, as an external camera or an in-vehicle camera of an automobile.

[0019] [Usage / Installation Examples] FIG. 2 shows examples of specifically using and installing the imaging device 1 of Embodiment 1, where (A) shows the first example and (B) shows the second example. In the first example of (A), the imaging device 1 is mounted inside the front glass (in other words, the windshield) 201 of the automobile 200, near the rearview mirror. In this case, the optical axis direction of the imaging unit 100 of the imaging device 1 faces the front direction (for example, the Y direction) of the automobile 200, and has a predetermined angle of view of 360 degrees around the axis in the Y direction. In this example, the angle of view is less than 180 degrees with respect to the Y axis.

[0020] In the second example of (B), the imaging device 1 is mounted on the outer side, upper side of, for example, the ceiling 202 of the vehicle body of the automobile 200. In this case, the optical axis direction of the imaging unit 100 of the imaging device 1 faces the vertical direction (Z direction), and has a predetermined angle of view of 360 degrees around the axis in the Z direction. In this example, the angle of view is wider than 180 degrees with respect to the Z axis. Note that the angle of view of the imaging device 1 can be changed by selecting and designing the angles of view of the two cameras that are the imaging unit 100.

[0021] Not limited to the above examples, the imaging device 1 may be installed, for example, on the upper side of the ceiling of the automobile 200 with the optical axis facing the front of the vehicle.

[0022] [Imaging Device and Processing Device (2)] Return to FIG. 1. The imaging device 1 is a device having at least a function of acquiring, using the imaging unit 100, an image for object recognition and two images (in other words, stereo images) from two viewpoints for distance measurement.

[0023] The first imaging unit 101 and the second imaging unit 102 are, for example, monocular cameras respectively. The first imaging unit 101 generates an imaging image signal based on the received light and outputs the imaging image signal (also referred to as the first image 31). Similarly, the second imaging unit 102 generates an imaging image signal based on the received light and outputs the imaging image signal (also referred to as the second image 32).

[0024] Generally, an image acquired, in other words, captured by an imaging device is transmitted to a processing device having a processor that executes processes such as detection of an object (in other words, object recognition) and distance measurement from the image. The processing device is, in other words, an image processing unit, a computer, etc. The processor includes semiconductor devices such as a CPU and a GPU. In Embodiment 1, the first image 31 and the second image 32, which are two images acquired by the first imaging unit 101 and the second imaging unit 102 of the imaging unit 100 of the imaging device 1, are transmitted to the processing device 3.

[0025] In the imaging device 1 of Embodiment 1, the imaging unit 100 and the processing device 3 are directly electrically connected via a mounting surface 4, particularly a substrate 40, by a predetermined signal line, in other words, a communication line or a connection line. The imaging unit 100 outputs and transmits an image acquired by imaging and other information to the processing device 3 through the signal line. Also, the imaging unit 100 may be controlled by a control signal through the signal line from the processing device 3 side. Further, the imaging unit 100 and the processing device 3 may be communicatively connected via a wired or wireless communication interface.

[0026] The processing device 3 in FIG. 1 includes a processor, a memory, a bus, an input / output interface, etc. The processing device 3 performs image processing including distance measurement based on the input of the first image 31 and the second image 32 which are two images from the imaging unit 100. Then, as a processing result, the processing device 3 has a function of outputting to the outside the first image and the second image which are two images, as well as data / information such as distance measurement information.

[0027] Note that although the imaging device 1 of Embodiment 1 is configured not to include the processing device 3, it is not limited thereto, and the imaging devices of other embodiments may be configured to include the processing device 3. In that case, the imaging device also has a function that the processing device 3 performs processing such as measuring the distance from two images acquired from the imaging unit 100. This imaging device can be alternatively referred to as a distance measurement device or the like.

[0028] The processing device 3 is a unit that performs image processing on two images of the imaging image signal from the imaging unit 100. The processing device 3 includes a first input interface 301 and a second input interface 302 as input interfaces, a first correction unit 311 and a second correction unit 312 as correction units, a stereo processing unit 320, and an output interface 330. The stereo processing unit 320 is, in other words, a distance measurement unit.

[0029] Each part (in other words, a functional block) of the processing device 3 is composed of predetermined hardware and software. Each part may be mainly realized by a dedicated circuit such as a circuit, for example, an FPGA, or at least a part thereof may be realized by software program processing. For example, the stereo processing unit 320 is realized by a processor such as a CPU executing processing according to a program on a memory. In the processing device 3 or an external storage device (not shown), various data / information such as programs and setting information are stored in advance. The processor appropriately reads and writes data / information in the processing process to the memory. Also, the image data of the two images acquired from the imaging unit 100, the image data after each processing, etc. are appropriately stored in the memory or the like.

[0030] The first input interface 301 receives and inputs the first image 31 from the first imaging unit 101. The second input interface 302 receives and inputs the second image 32 from the second imaging unit 102. Each of the input interfaces includes, for example, an analog / digital converter, converts an imaging image signal, which is an analog signal from the imaging unit 100, into a digital signal, and outputs it to a subsequent functional block.

[0031] Connected to the subsequent stage of the input interface are a first correction unit 311 and a second correction unit 312 as correction units. The first correction unit 311 corrects the imaging image signal (also referred to as the first image 33), which is a digital signal output from the first input interface 301, by performing various predetermined image processes, and outputs it to a subsequent functional block. Similarly, the second correction unit 312 corrects the imaging image signal (also referred to as the second image 34), which is a digital signal output from the second input interface 302, by performing various predetermined image processes, and outputs it to a subsequent functional block. The image processes executed by the correction unit are, for example, general-purpose geometric transformations. By this geometric transformation image process, an imaging image having distortion in a coordinate system corresponding to the imaging optical system can be converted into an image in a predetermined coordinate system suitable for stereo processing. The image processes executed by the correction unit may also include, for example, demosaicking processing.

[0032] A stereo processing unit 320 is connected to the subsequent stage of the correction unit. The stereo processing unit 320 performs stereo processing, that is, distance measurement processing, using two captured images (also referred to as the first image 35 and the second image 36) output from the correction unit. As a result of this processing, the stereo processing unit 320 extracts distance information, that is, information representing the distance between the imaging unit 100 and the object. The stereo processing unit 320 creates distance image data, which is an image including the distance information (in other words, distance measurement result information). The distance image data is, for example, a distance image having a distance value for each pixel in the image, or in other words, data of a distance image in which the distance to the object is represented by color or luminance for each position coordinate in the image. Then, the stereo processing unit 320 outputs the distance image data to an output interface 330, which is a functional block in the subsequent stage. Also, the stereo processing unit 320 outputs the data of the first image 35 and the second image 36, which are the respective captured images from the correction unit, to the output interface 330. The output data 37 is data including the above distance image data and two captured images.

[0033] An output interface 330 is connected to the subsequent stage of the stereo processing unit 320. The output interface 330 outputs output data 38 corresponding to the output data 37 including the distance image data and the captured image data output from the stereo processing unit 320 to an external device. Examples of the external device include a control device that uses and controls the imaging device 1. The external device may be, for example, an electronic control unit (ECU) mounted on an automobile 200 as shown in FIG. 2. The external device may be a computer of a robot on which the imaging device 1 is mounted. The external device may be a server device on a communication network or the like. The output interface 330 may be a device on which a communication interface with the external device is implemented. In the case of the example in FIG. 2, the processing device 3 in FIG. 1 may be installed in the automobile 200 integrally with the imaging device 1, or may be installed on the side of the ECU or the like of the automobile 200.

[0034] [Comparative Example A] FIG. 14 shows the configuration of an imaging device 1A of a comparative example (referred to as Comparative Example A) with respect to the imaging device 1 (FIG. 3 described later) of Embodiment 1. In FIG. 14, an example of the positional relationship between the two cameras of the imaging unit 100A and the cover 2A in the imaging device 1A of Comparative Example A is shown in a schematic perspective view. The imaging device 1A of Comparative Example A includes a first imaging unit 101A and a second imaging unit 102A as the imaging unit 100A, and a cover 2A that houses them. The imaging unit 100A and the cover 2A are installed on the installation surface 4A.

[0035] The installation surface 4A is a rectangular region indicated by a dot pattern and is arranged in the illustrated X - Y plane. The first imaging unit 101A and the second imaging unit 102A are installed at predetermined positions on the installation surface 4A. The first imaging unit 101A and the second imaging unit 102A are arranged at two predetermined positions at a predetermined distance, for example, on a straight line in the X direction. The first imaging unit 101A has a first viewpoint P1A, and the second imaging unit 102A has a second viewpoint P2A. As shown by the dashed - dotted line arrows, the optical axes of these imaging units are directed in the Z direction. The optical axis J1A indicates the optical axis of the first imaging unit 101A, and the optical axis J2A indicates the optical axis of the second imaging unit 102A. The field of view V1A indicates a predetermined angle of view centered on the optical axis J1A, and in this example, it is an imaging field of view with an angle of view of about 60 degrees in the X - Z plane. The field of view V2A indicates a predetermined angle of view centered on the optical axis J2A, and in this example, it is an imaging field of view with an angle of view of about 60 degrees in the X - Z plane.

[0036] A cover 2A is fixed on the installation surface 4A so as to cover the first imaging unit 101A and the second imaging unit 102A, which are two imaging units. In other words, two cameras are housed in the space partitioned by the cover 2A. The shape of this cover 2A is an example of a simple rectangular parallelepiped, and it has an upper surface parallel to the installation surface 4A and four side surfaces perpendicular to the installation surface 4A. Note that one plane corresponding to the installation surface 4A among the six planes of the rectangular parallelepiped of the cover 2A is missing.

[0037] The first imaging unit 101A is a first camera that generates a first image, which is an output image, based on a group of light rays traveling from a subject within the visual field V1A toward the first viewpoint P1A of the first imaging unit 101A. The second imaging unit 102A is a second camera that generates a second image, which is an output image, based on a group of light rays traveling from a subject within the visual field V2A toward the viewpoint P2A of the second imaging unit 102A.

[0038] Also, the common visual field V3A is shown as a lattice pattern area in the drawing and is the overlapping portion of the two visual fields (V1A, V2A) of the two imaging units. The common visual field V3A indicates a spatial area where distance measurement as a stereo camera is possible.

[0039] The light rays a1 and a2 illustrate some of the light rays belonging to the group of light rays within these visual fields. For example, the light ray a1 indicates a light ray that enters the first viewpoint P1A from top to bottom in the Z direction within the visual field V1A of the first imaging unit 101A. The light ray a2 indicates a light ray that enters the second viewpoint P2A from top to bottom in the Z direction within the visual field V2A of the second imaging unit 102A. Therefore, this imaging unit 100A generates and acquires two images, which are different output images from the two imaging unit viewpoints, namely the first viewpoint P1A and the second viewpoint P2A.

[0040] Here, the viewpoint, or the imaging unit viewpoint, or the camera viewpoint, in other words, is the position of the entrance pupil as an optical system. Specifically, in an example, the viewpoint is the position of the image sensor that constitutes the camera.

[0041] The cover 2A is a light-transmissive member made of a material that transmits the wavelength of the imaging target. When the cover 2A is for visible light, it is made of a material such as glass or resin, for example, and when it is for infrared light, it is made of a material such as germanium, for example. The cover 2A is provided for purposes such as dust and drip prevention of the imaging unit 100A, for example.

[0042] Problems in Comparative Example A of FIG. 14 and the like will be described. Generally, as a shape often adopted as a cover, a rectangular parallelepiped shape composed of a plurality of planes, such as the example of cover 2A, can be cited. In the case of the cover 2A having such a rectangular parallelepiped shape, the light reflected by the cover 2A enters the imaging unit 100. In the example of FIG. 14, the light ray a3 enters the cover 2A from outside the two fields of view (V1A, V2A), passes through, for example, one side surface of the rectangular parallelepiped, and is reflected downward in the Z direction on the upper plane of the rectangular parallelepiped, and is incident on the second viewpoint P2A of the second imaging unit 102A. As a result, light outside the intended field of view (for example, light ray a3) is mixed with the light inside the field of view (for example, light ray a2). As a result, the reflected light of the light ray a3 appears as stray light in the output image of the second imaging unit 102A. When stray light appears in the output image, the accuracy of image recognition and distance measurement using the output image decreases.

[0043] Therefore, as shown in FIG. 3 described later, the imaging device 1 of Embodiment 1 has a devised shape of the cover 2, and prevents or suppresses stray light (particularly reflected light by the cover) caused by the mixing of light outside the field of view as described above. Specifically, in the imaging device 1 of Embodiment 1 in FIG. 3, the shape of the cover 2 has an ellipsoidal surface shape. Thereby, such stray light is suppressed.

[0044] [Imaging Device and Cover] FIG. 3 shows the configuration of the imaging unit 100 and the cover 2 of the imaging device 1 of Embodiment 1. In FIG. 3, an example of the positional relationship between the two cameras of the imaging unit 100 and the cover 2 in the imaging device 1 is shown in a schematic perspective view. In the example of FIG. 3, the imaging device 1 is arranged in the illustrated coordinate system (X, Y, Z). The installation surface 4 is an elliptical region indicated by a dot pattern and is arranged on the X - Y plane shown. The first imaging unit 101 and the second imaging unit 102 are installed at predetermined positions on the installation surface 4. The first imaging unit 101 and the second imaging unit 102 are arranged at two predetermined positions with a predetermined distance, for example, on a straight line in the X direction.

[0045] The first imaging unit 101 has a first viewpoint P1 on the straight line 300, and the second imaging unit 102 has a second viewpoint P2. As shown by the dashed arrow, the optical axes of these imaging units are oriented in the Z direction. The optical axis J1 represents the optical axis of the first imaging unit 101, and the optical axis J2 represents the optical axis of the second imaging unit 102. The field of view V1 represents an imaging field of view with a predetermined angle of view centered on the optical axis J1, which is about 90 degrees in the X-Z plane in this example. The field of view V2 represents an imaging field of view with a predetermined angle of view centered on the optical axis J2, which is about 90 degrees in the X-Z plane in this example.

[0046] On the installation surface 4, a cover 2 is fixed so as to cover the first imaging unit 101 and the second imaging unit 102, which are two imaging units. In other words, two cameras are housed in the space partitioned by the cover 2.

[0047] The cover 2 is a cover made of a material having light transmissibility with respect to light to be imaged (for example, visible light), and in other words, it is a protective member or a fixing member. The cover 2 has at least a function of protecting the imaging unit 100, and for example, has a dust-proof and drip-proof function of preventing dust and liquid from adhering to the imaging unit 100. Further, the cover 2 in Embodiment 1 has a function of preventing and reducing the incidence of stray light (that is, reflected light due to external light other than light from the subject) to the imaging unit 100.

[0048] As a basic requirement of the cover 2, it is necessary that the cover 2 does not interfere with the imaging unit 100. In other words, as a condition for the size of the cover 2, it is necessary that the viewpoints (P1, P2) of the two cameras of the imaging unit 100 are accommodated in the space inside the approximate hemispherical surface of the cover 2.

[0049] The cover 2 has a shape such that light rays from the vicinity of the first viewpoint P1 of the first imaging unit 101 (the cover first focal point F1 described later) are reflected by the cover 2 and directed toward the vicinity of the second viewpoint P2 of the second imaging unit 102 (the cover second focal point F2 described later), or a shape such that light rays from the vicinity of the second viewpoint P2 are reflected by the cover 2 and directed toward the vicinity of the first viewpoint P1. More specifically, the cover 2 has a shape that realizes such an action, and has a shape of a rotational ellipsoidal surface, in other words, an elliptical curved surface shape.

[0050] In FIG. 3, the cover 2 occupies a space as a schematic hemispherical surface on the installation surface 4, and has a shape of a rotational ellipsoidal surface as the detailed shape of the hemispherical surface. Note that the elliptical planar portion of the schematic hemispherical surface of the cover 2 that is in contact with the installation surface 4 is missing, and when the imaging device 1 is disassembled into the cover 2 and the like, that portion is an opening. The cover 2 may have a configuration having a rotational ellipsoidal surface shape at least in part of the whole when the whole is a schematic hemispherical surface.

[0051] The first imaging unit 101 is a first camera that generates a first image, which is an output image, based on a group of light rays directed from a subject in the visual field V1 toward the first viewpoint P1 of the first imaging unit 101. The second imaging unit 102 is a second camera that generates a second image, which is an output image, based on a group of light rays directed from a subject in the visual field V2 toward the viewpoint P2 of the second imaging unit 102. Also, the common visual field V3 is shown as a grid pattern area in the drawing, and is a portion where the two visual fields (V1, V2) of the two imaging units overlap. The common visual field V3 indicates a spatial area where distance measurement as a stereo camera is possible.

[0052] The light rays A1 and A2 illustrate some of the light rays belonging to the group of light rays within these visual fields. For example, the light ray A1 indicates a light ray that enters the first viewpoint P1 from above downward in the Z direction within the visual field V1 of the first imaging unit 101. The light ray A2 indicates a light ray that enters the second viewpoint P2 from above downward in the Z direction within the visual field V2 of the second imaging unit 102. The imaging unit 100 generates and acquires two images, which are different output images from the two viewpoints, the first viewpoint P1 and the second viewpoint P2.

[0053] The ellipsoidal surface in this cover 2 is a curved surface formed by rotating an elliptical curve with the straight line 300 connecting the first imaging unit 101 (particularly the first viewpoint P1) and the second imaging unit 102 (particularly the second viewpoint P2), which are two imaging units, as the rotation axis. The straight line 300 of this rotation axis is, specifically, the straight line connecting the first viewpoint P1 and the second viewpoint P2, which are two viewpoints, and in other words, it is the rotation axis. In the example of FIG. 3, the straight line 300, the first viewpoint P1, and the second viewpoint P2 are located at a position a predetermined distance above the X-Y plane, which is the installation surface 4, in the Z direction.

[0054] Furthermore, the two foci (F1, F2) of the ellipsoidal surface of this cover 2 are defined as the cover first focus F1 and the cover second focus F2. In this case, in the configuration of Embodiment 1, these two foci (F1, F2) respectively coincide with, in other words, are approximately made to coincide with, the first viewpoint P1 and the second viewpoint P2, which are the two viewpoints of the first imaging unit 101 and the second imaging unit 102, which are two imaging units. In FIG. 3, there is a cover first focus F1 near the first viewpoint P1, for example, on the right side in the X direction, and there is a cover second focus F2 near the second viewpoint P2, for example, on the right side in the X direction. Note that the relationship between the cover first focus F1 with respect to the first viewpoint P1 and the relationship between the cover second focus F2 with respect to the second viewpoint P2 are the same relationship, for example, a relationship of a predetermined distance on the right side in the X direction, but it is not limited to this.

[0055] Here, the coincidence of the camera viewpoint and the cover focus, which are two types of positions, means that these two points exist in the vicinity of the scale of the size of the imaging unit 100. In other words, it is sufficient that the camera viewpoint and the cover focus are arranged with a rough coincidence at the scale of the size of the imaging unit 100. Details of such coincidence conditions will be described later. In the case of a configuration that satisfies such coincidence conditions, based on the characteristics of the ellipsoidal surface of the cover 2, the light rays from one camera viewpoint are reflected by the shape of the ellipsoidal surface of the cover 2 and enter the other camera viewpoint. For example, the light ray A3 from the first viewpoint P1 of the first imaging unit 101 shown in the figure is reflected by the shape of the ellipsoidal surface of the cover 2, and the reflected light ray A4 enters the second viewpoint P2 of the second imaging unit 102.

[0056] When external light is incident on and reflected from the inner curved surface which is the inner surface of the cover 2, light rays such as external light incident from directions other than the cover focus will not head towards the camera viewpoints near the cover focus after being reflected by the inner surface of the cover 2. This is due to the characteristics of the ellipsoidal surface of revolution. Therefore, it is possible to prevent such light rays as the external light from becoming stray light.

[0057] Note that the shape of the ellipsoidal surface of revolution of the cover 2 is not limited to a mathematically exact ellipsoidal surface of revolution, and it may be a schematic ellipsoidal surface of revolution. In other words, when the cover 2 is based on an exact ellipsoidal surface of revolution, it may be an elliptical curved surface whose shape is deviated within a certain allowable range from the reference ellipsoidal surface of revolution. Even in this case, the reflected light suppression effect and the stray light reduction effect by the cover 2 can be obtained accordingly.

[0058] [Positional Relationship and Coincidence Conditions] FIG. 4 shows an explanatory diagram regarding the positional relationship between the imaging unit 100 and the cover 2, and the above-mentioned coincidence conditions, which relates to the imaging device 1 and the like of the first embodiment in FIG. 3. In FIG. 4, a perspective view of the cover 2 and the like similar to FIG. 3 is used to show the relationship between the size and shape of the cover 2 and the size and shape of the imaging unit 100, and the positional relationship between the viewpoints of the imaging unit 100 and the foci of the cover 2. In FIG. 4, the major axis radius which is the first radius of the ellipsoidal surface of revolution of the cover 2 is denoted as a, the minor axis radius which is the second radius is denoted as b, and the distance between the two viewpoints, the first viewpoint P1 and the second viewpoint P2, is denoted as c and shown in the figure.

[0059] The size of the cover 2 is defined by the two variables, the major axis radius a and the minor axis radius b. The minimum values of the two variables (a, b) can be determined by defining the following two conditions. The first condition is that the positions of the two viewpoints (P1, P2) of the imaging unit 100 and the two foci (F1, F2) of the cover 2 coincide with each other. At this time, the following condition of Equation 1 is given between the distance c between the viewpoints, the major axis radius a, and the minor axis radius b. Equation 1: c = 2√(a 2 -b 2 )

[0060] The second condition is that there is no interference between the first imaging unit 101 and the second imaging unit 102 that constitute the imaging unit 100 and the cover 2. At this time, considering the size and position of the imaging unit 100, the lower limit values of the two variables (a, b) are determined. The size of the first imaging unit 101 is shown with a scale of s1, and the size of the second imaging unit 102 is shown with a scale of s2.

[0061] While satisfying the condition of this lower limit value, the values of the two variables (a, b) calculated from the condition of Equation 1 are the values that define the size of the cover 2 to be obtained. Since the values of these variables (a, b) are the minimum values, as long as Equation 1 is satisfied, larger values may also be used.

[0062] In FIG. 4, let the distance between the first viewpoint P1 of the first imaging unit 101 and the first focus F1 of the cover be d1. Let the distance between the second viewpoint P2 of the second imaging unit 102 and the second focus F2 of the cover be d2. In this case, the above-mentioned coincidence condition means that for the relationship between the first viewpoint P1 and the first focus F1 of the cover, the distance d1 is within the scale s1, and in a mathematical formula, it is expressed as d1≤s1 for example. Similarly, for the relationship between the second focus P2 and the second focus F2 of the cover, the distance d2 is within the scale s2, and it is expressed as d2≤s2. In other words, the coincidence condition is that for one or more imaging units, the distance between the imaging unit viewpoint and the cover focus is less than or equal to the size of the entrance pupil (for example, the lens center region) of the imaging unit. Such a condition is derived from general optics.

[0063] The imaging device 1 of Embodiment 1 in FIG. 3 satisfies the above-mentioned coincidence condition (in other words, the substantially coincidence condition) as the configuration of the imaging unit 100 and the cover 2. In the following, for the sake of clarity in explanation, there may be cases where it is assumed that the viewpoint of the imaging unit 100 and the focus of the cover 2 are at the same position, or the camera viewpoint and the cover focus are the same for explanation.

[0064] Note that, as an arrangement that satisfies the above matching conditions, in FIG. 4, the first imaging unit 101 and the second imaging unit 102, which are two cameras, are both arranged such that they have a distance d to the left with respect to the cover focus. However, it is not limited to this, and within the range that satisfies the matching conditions, with respect to each cover focus, each camera focus may be arranged in different directions or at different distances.

[0065] [Function of the Cover] Returning to FIG. 3, the operation and effects of configuring the imaging unit 100 and the cover 2 as described above in the first embodiment will be described. In the arrangement of FIG. 3, for example, the light ray A4 is a cover reflected light ray that travels toward the second viewpoint P2 of the second imaging unit 102, that is, the cover second focus F2 that coincides with the second viewpoint P2. This light ray A4 is the reflected light corresponding to the light ray A3 emitted from the cover first focus F1. The reflection from the light ray A3 to the light ray A4 is due to the property of the foci of the ellipse on the ellipsoidal surface of the cover 2. Here, the cover first focus F1 and the first viewpoint P1, as well as the cover second focus F2 and the second viewpoint P2, respectively satisfy the above-described matching conditions. Therefore, the light ray A3 becomes light that exits from the vicinity of the first viewpoint P1, which is the entrance pupil of the first imaging unit 101. Thus, in this case, the light that may be reflected as stray light in the output image (the second image 32 in FIG. 1) of the second imaging unit 102 is limited to only the light from the first viewpoint P1, which is the entrance pupil of the first imaging unit 101, and the portion of the first imaging unit 101 in the vicinity thereof.

[0066] Therefore, in Embodiment 1, as shown in FIG. 5 described later, as most of the first imaging unit 101, the portion excluding the incident region to the first viewpoint P1 is, for example, painted black, in other words, as the formation of a light reflection suppressing member, a configuration is adopted to suppress the reflected light in the first imaging unit 101. Thereby, reflected light such as the light ray A3 from the portion near the first viewpoint P1 of the first imaging unit 101 is suppressed, and the reflection of the reflected light on the inner surface of the cover 2 and the incidence near the second viewpoint P2 of the second imaging unit 102 as the light ray A4 are suppressed. Thereby, stray light reflected in the output image of the second imaging unit 102 can be suppressed. Such an effect also holds true for the light from the second imaging unit 102 to the first imaging unit 101 (for example, considering the light rays A3 and A4 in the reverse direction).

[0067] In the example of FIG. 3, when the light ray A1 is regarded as 100% light, when the light ray A1 first enters the cover 2, due to the action of the cover 2, for example, it is attenuated to 10% light. The incident 10% light is reflected by the lens of the first imaging unit 101 and becomes the light ray A3. At this time, the lens of the first imaging unit 101 is generally configured with an antireflection coating. Therefore, the incident 10% light is reflected by the lens of the first imaging unit 101, and after reflection, the light ray A3 is attenuated to, for example, about 1% light. The 1% light ray A3 is reflected by the inner surface of the cover 2 and becomes the light ray A4. At this time, due to the reflection of the light ray A3 on the inner surface of the cover 2, after reflection, the light ray A4 is attenuated to, for example, about 0.1% to 0.01% light.

[0068] This light ray A4 is light that can enter the lens of the second imaging unit 102 and become stray light. This light ray A4 has a light amount that is sufficiently small, about 0.1% to 0.01% with respect to the original light ray A1. Therefore, the stray light reflected in the image of the second imaging unit 102 can be suppressed to be sufficiently small. Furthermore, by configuring the portions other than the lens of the imaging unit 100 to be painted black, the stray light can be further reduced.

[0069] As a modification, the cover 2 may be configured such that an antireflection coating is applied to the inner surface, which is the surface exposed in the inner space of the cover 2. In the case of this configuration, for example, reflected light during reflection from the light beam A3 to the light beam A4 can be further reduced in intensity.

[0070] [Configuration example of light reflection suppression of imaging unit] FIG. 5 shows a configuration example of black painting of the above-described imaging unit 100, that is, formation of a light reflection suppression member. In the example of FIG. 5, for the first imaging unit 101, most of the portion exposed on the installation surface 4, excluding the region of the first viewpoint P1 centered on the optical axis J1, specifically, the portion of the lens that forms an image on the image sensor in the housing, is painted black, and a light reflection suppression member is formed (for example, coated). In FIG. 5, the lens region 501 is illustrated in white. Since the lens region 501 is necessary for imaging, it is not painted black. In the example of FIG. 5, the lens barrel is also painted black. Further, the housing portion incorporating the image sensor and the like as a rectangular parallelepiped portion below the lens barrel is also painted black.

[0071] The light reflection suppression member is a member having a low reflectance of light of a target wavelength, such as a light-shielding film. By using in combination a configuration in which such a light reflection suppression member is provided, the effect of suppressing reflected light by the cover 2 can be further enhanced.

[0072] The light incident on the first imaging unit 101, for example, the light beam A5, shows an example of a light beam incident on the upper surface, side surface, etc. other than the lens region 501. Even if such a light beam A5 is incident, reflected light directed toward the cover 2, like the light beam A3 in FIG. 3, is suppressed. Therefore, the light incident on the lens region corresponding to the second viewpoint P2 of the second imaging unit 102, which coincides with the second focal point F2 of the cover, like the light beam A4 in FIG. 3, is suppressed.

[0073] As a modification, on the installation surface 4, a configuration may be adopted in which a light reflection suppression member is provided in a region including the imaging unit and its surroundings, for example, the region 501 indicated by the broken line.

[0074] [Regarding the arrangement region of the cover] Return to FIG. 3. In the space, the cover 2 is arranged in a shape of a rotational ellipsoidal surface with a predetermined shape so as to include a region corresponding to a part or all of the fields of view (V1, V2) of the first imaging unit 101 and the second imaging unit 102. In other words, the cover 2 is arranged in a predetermined shape so as to include a region (in other words, an intersecting region) through which part or all of the light rays of the fields of view (V1, V2) pass. In the first embodiment, as shown in FIG. 3, the cover 2 is arranged with a rotational ellipsoidal surface shape over all of the surface region of a roughly hemispherical shape on the upper side from the installation surface 4. In a part of this roughly hemispherical surface region, the fields of view (V1, V2) intersect, and all the light rays of the fields of view (V1, V2) pass through.

[0075] The region and size where the cover 2 is provided are not limited to the configuration example of FIG. 3, and a modification example as shown in FIG. 6 described later is also possible. It is sufficient that at least a part of the entire cover of the imaging device has a shape of a roughly rotational ellipsoidal surface. The region in the space where the cover 2 is provided may be at least a part including the region where it is desired to suppress stray light due to reflection by the cover 2.

[0076] [Modification example: Cover] FIG. 6 shows the configuration of the cover 2b and the like in the imaging device 1b which is a modification example of the first embodiment. This cover 2b is provided corresponding to a part of a roughly hemispherical surface while covering the fields of view (V1, V2) of the two cameras of the imaging unit 100. In the example of FIG. 6, the case where the fields of view of the cameras are narrower than those in FIG. 3 is shown. Specifically, this cover 2b has a shape in which a part of the rotational ellipsoidal surface of the roughly hemispherical region in FIG. 3 is cut out. In this example, the cut-out part is the left part from the semi-elliptical plane 601 shown, which is on the left side in the X direction with respect to the first imaging unit 101. The plane 601 is the Y-Z plane at the boundary between the cover 2b and the cut-out part.

[0077] In the example of FIG. 6, it is assumed that there is no external light incident on the plane 601 in the installation and use environment of the imaging device 1b. In this case, it is not necessary to consider the reflection of external light in a partially cut-out region corresponding to this plane 601. Therefore, in this modified example, a cover, particularly a cover having an ellipsoidal shape of revolution, is not provided in this partially cut-out region.

[0078] The plane 601 may be, for example, an opening provided without anything. In this case, basically, the space inside the cover 2b is open to the outside through this plane 601. Depending on the usage example of the imaging device 1, such a plane 601 of the opening is arranged in contact with a part of the object to be mounted, for example, a part of the surface of the automobile 200 in FIG. 2. In that case, the plane 601 closes the space inside the cover 2b by the surface of the object. In this case, the function of dust prevention and the like by the cover 2b is realized.

[0079] Also, depending on the usage example, the opening of the plane 601 may be left as it is without being blocked by the surface of the object. For example, the opening of the plane 601 may be used as a ventilation hole, or may be used for arranging signal lines and other mounted objects. For example, when functions such as dust prevention are not required, the plane 601 may be left as an opening in this way.

[0080] Also, as another configuration example, a flat light transmissive member may be provided on the plane 601 to form a part of the cover 2b, and the space inside the cover 2b may be closed.

[0081] [Regarding the installation surface and the substrate] Return to FIG. 3. In FIG. 3, the installation surface 4 where the imaging unit 100 is installed corresponds to the bottom surface portion and the opening of the cover 2. The installation surface 4 is, for example, the surface of an object on which the imaging device 1 is installed, such as a part of the automobile 200 in FIG. 2 (for example, the vehicle body, rearview mirror, etc.). Alternatively, the installation surface 4 is not the surface of the object on which the imaging device 1 is installed, but a substrate or the like made of a member different from the object as one of the components of the imaging device 1. In Embodiment 1, in particular, it is assumed that the installation surface 4 is such a substrate 40. The substrate 40 is, in other words, an imaging unit installation substrate and a cover bottom plate. The imaging unit 100 is fixed on the substrate 40. When the imaging device 1 is installed on the object, this substrate 40 is interposed between the object surface. For example, the substrate 40 is disposed on the object surface. In Embodiment 1, the imaging unit 100 is surrounded on all sides by the cover 2 and the substrate 40 which is the installation surface 4, and the space in which the imaging unit 100 is accommodated is closed.

[0082] When the imaging unit 100 and the cover 2 are directly installed or mounted on the surface of an object (for example, the automobile 200), the substrate 40 is unnecessary. However, in that case, it is necessary to fix the positional relationship between the imaging unit 100 and the cover 2 on the installation surface 4 to a predetermined appropriate positional relationship. When positioning this predetermined positional relationship with high precision, it is better to use the installation surface 4 as the substrate 40 as in Embodiment 1.

[0083] The substrate 40 which is the installation surface 4 and the end of the cover 2 (that is, the elliptical opening) may be fixed by any fixing means, for example, screwing, adhesive, fitting structure by claw-shaped or spiral protrusions, etc., and the cover 2 may be removable from the substrate 40 during maintenance or the like.

[0084] As a modification, a form in which the cover 2 and the substrate 40 are integrated into one cover may be used.

[0085] In addition, the substrate 40 which is the installation surface 4 is not limited with respect to optical characteristics and constituent members, and may be constituted by a light transmissive member or may be constituted by a light reflection suppressing member. In Embodiment 1, the entire upper surface of the substrate 40 which is the installation surface 4 may be constituted by a light reflection suppressing member. The light reflection suppressing member of the substrate 40 may be a light reflection suppressing member similar to that shown in FIG. 5.

[0086] In addition, in the space surrounded by the cover 2 and the installation surface 4, that is, in the substantially hemispherical space shown schematically in FIG. 3, it is preferable that nothing other than the two imaging units 100 which are cameras is arranged in order to prevent stray light.

[0087] In addition, the processing device 3 etc. of FIG. 1 may be arranged on the back side of the substrate 40 which is the installation surface 4.

[0088] [Modification Example: Distance Measuring Device] FIG. 7 shows a configuration example of a distance measuring device 10 including an imaging device 1 as a modification example of Embodiment 1. In this distance measuring device 10, a cylindrical or disk-shaped housing 700 is connected to the lower side of the substrate 40 of the imaging device 1 as shown in FIG. 3. And, in the housing 700, the processing device 3 etc. of FIG. 1 are provided. In FIG. 7, the mounted object of the processing device 3 is arranged on the bottom surface inside the housing 700. Not limited to this, the mounted object of the processing device 3 may be arranged on the back surface of the substrate 40 which is the installation surface 4 inside the housing 700. The processing device 3 etc. may be mounted on the substrate 40. In other words, the distance measuring device 10 is an imaging device including the processing device 3 including the stereo processing unit 320, and an imaging device with a distance measuring function.

[0089] The first imaging unit 101 and the second imaging unit 102 are connected to the processing device 3 through the signal line 701 via the substrate 40 which is the installation surface 4. In addition, a battery, a communication interface device etc. may be provided in the housing 700. In addition, an input / output interface, an operation input button etc. may be provided on the housing 700.

[0090] As another modification, the substrate 40 serving as the installation surface 4 may also be made of a light-transmissive member, just like the cover 2. In that case, the substrate 40 serving as the installation surface 4 can also be regarded as a part of the cover 2. Also, as described above, the cover 2 needs to be arranged while maintaining a predetermined positional relationship that satisfies the matching conditions as shown in FIGS. 3 and 4 with respect to the imaging unit 100. Therefore, usually, the cover 2 is fixed to the installation surface 4. However, if the predetermined positional relationship between the cover 2 and the imaging unit 100 can be maintained, it is not necessarily required that the cover 2 be fixed to the installation surface 4.

[0091] As another modification, the cover 2, the substrate 40 serving as the installation surface 4, the housing 700, etc. may all be formed of light-transmissive members, and a light reflection suppression member or the like may be provided only at necessary locations.

[0092] In the examples of FIGS. 3 and 7, the substrate 40 serving as the installation surface 4 is in the shape of an elliptical plate, but it is not limited thereto, and it may be in the shape of a rectangular plate including the elliptical plane at the end of the cover 2, for example. Also, the housing 700 in FIG. 7 is not limited to a cylindrical shape, and may be in the shape of a rectangular parallelepiped including the processing device 3, etc. and including the elliptical plane at the end of the cover 2, for example.

[0093] [Effects, etc.] According to the imaging device 1 of the first embodiment, by devising the shape of the cover 2 as a rotational ellipsoidal surface shape, the influence of the reflected light by the cover 2 can be suppressed, and the entry of stray light into the acquired image through the imaging unit 100 can be prevented or reduced. Thereby, a decrease in the accuracy of image recognition and distance measurement can be prevented or reduced. In the first embodiment, by making the cover 2 in the shape of a rotational ellipsoidal surface, the light reflected by the cover 2 and incident on the viewpoint of one camera (for example, the light ray A4 in FIG. 3) is limited to the light (for example, the light ray A3) emerging from the vicinity of the viewpoint of the other camera. Thereby, the influence of the reflected light at the cover can be suppressed.

[0094] As a modification of Embodiment 1, the following is also possible. In the modification, the imaging device 1 is installed in such a direction that the optical axis of the imaging unit 100 passes through the windshield 201 of the automobile 200, similar to FIG. 2(A). In this modification, the imaging device 1 may be installed or mounted on a part of the windshield 201, and a part of the windshield 201 may be integrally configured as the cover 2. Specifically, in the curved surface of the windshield 201, a region including a portion where the fields of view (V1, V2) of the two cameras intersect is configured as the cover 2 having an ellipsoidal surface shape, similar to FIG. 3. This part of the cover 2 serves functions such as suppressing reflected light, similar to FIG. 3. For example, in the automobile 200, there may be a high-functional windshield equipped with a camera, a sensor, etc., or a high-functional windshield implemented as a display such as a head-up display. In that case, a configuration in which the cover 2 of the imaging device 1 as described above is mounted on a part of the high-functional windshield can be applied.

[0095] As another modification, three or more imaging units may be provided in the cover 2. For example, a configuration in which three cameras are arranged at predetermined intervals on a straight line on the installation surface 4 and these three cameras are covered by the cover 2 can be cited. Regarding three or more imaging units in the cover 2, the configuration is not limited to making all viewpoints coincide with the cover focus. Depending on the importance of the imaging units, etc., a configuration may be adopted in which only some of the imaging units are arranged with the viewpoints coinciding with the cover focus. The three cameras may have different characteristics such as angle of view. For example, two cameras on both sides out of the three may form a stereo camera with a predetermined angle of view, and the one camera in the center may be a camera with a different angle of view. Also, a configuration in which two cameras are arranged near the first position and one camera is arranged near the second position on the installation surface 4 is also possible.

[0096] As the first imaging unit 101 and the second imaging unit 102 in the imaging unit 100, a configuration combining a lens, which is a refractive optical system, and an image sensor may be adopted respectively, or a reflective optical system configuration with a hyperbolic mirror added thereto may be adopted.

[0097] Also, the cover 2 is not limited to being transparent, and may be, for example, translucent. The cover 2 may have a rotational ellipsoidal shape only for the portion that intersects the camera's fields of view (V1, V2), and a non-rotational ellipsoidal shape for the other portions.

[0098] The imaging device according to the embodiment is not limited to being installed in an automobile or an autonomous driving robot, and as an example of other installation locations, it may be installed in, for example, a vehicle such as a motorcycle or a drone.

[0099] <Embodiment 2> The imaging device according to Embodiment 2 will be described with reference to FIG. 8. The basic configuration of Embodiment 2 and the like is the same as that of Embodiment 1, and hereinafter, the components different from those of Embodiment 1 in Embodiment 2 and the like will be mainly described. In Embodiment 2, an example of installing the imaging device in a headlight unit (headlight 203 in FIG. 2) of an automobile is shown.

[0100] FIG. 8 shows an example of a configuration mounted on a headlight unit 801 in the imaging device 1c according to Embodiment 2. FIG. 8 shows an example of the positional relationship among the first imaging unit 101 and the second imaging unit 102, which are two cameras of the imaging unit 100, the cover 2c, and the headlight unit 801. In FIG. 8, as for the arrangement, the Y direction shown in the figure is the front of the automobile, the X direction is the left-right direction of the automobile, and the Z direction is the vertical direction. The imaging unit 100 in this headlight unit 801 functions as a sensor of the automobile.

[0101] In FIG. 8, in one of the left and right headlight units 801, a light source device 800 is provided on the installation surface 4 (X-Z plane). Here, the installation surface 4 is a part of the vehicle body. The installation surface 4 has, as an example, a plane extending in the X direction and an inclined surface with respect to the X direction.

[0102] In the case of a headlight, in order to control the light distribution characteristics of the illumination light, the periphery of each sensor (imaging unit 100 in this example) may also be formed of a light reflecting member. The light reflecting member is a member made of a material with a high reflectivity of illumination light. In that case, the light reflected by those light reflecting members may be reflected again by the cover 2 and enter the imaging unit 100 corresponding to the sensor, becoming stray light.

[0103] Therefore, in the second embodiment, the sensor having the first viewpoint P1 is the first imaging unit 101, and the sensor having the second viewpoint P2 is the second imaging unit 102. And in the second embodiment, similar to the first embodiment, the cover 2c and the imaging unit 100 are arranged so as to satisfy the condition that the cover first focus F1 and the cover second focus F2, which are the two foci of the cover 2c, coincide with the first viewpoint P1 and the second viewpoint P2, which are the two viewpoints of the imaging unit 100. Thereby, it is possible to suppress the stray light caused by the reflected light at the cover 2c. The cover 2c of this imaging device 1 may be the cover of the headlight unit 801 or a part of the cover.

[0104] The installation surfaces 4 of the two cameras of the imaging unit 100 are not limited to a single plane, and may be a plurality of planes as in this example, or may be a curved surface or the like. In any mode of the installation surface 4, the cover 2c may be formed in an ellipsoidal surface shape such that the relationship between the foci (F1, F2) of the cover 2c with respect to the viewpoints (P1, P2) of the two cameras satisfies the above-mentioned coincidence condition.

[0105] The light source device 800 includes, as an example, a light source 80A and a reflector 80B. The reflector 80B is a device for controlling the light distribution characteristics of the light source 80A. A part of the light emitted from the light source 80A is reflected and condensed by the reflector 80B and emitted as a light beam directed forward of the vehicle.

[0106] Also, the installation surface 4 as a part of the headlight unit 801, in other words, the bottom surface of the headlight, is made of, for example, a light reflecting member, that is, a member made of a material with a high reflectivity of the light source light. Thereby, the light utilization efficiency as the headlight unit 801 is enhanced.

[0107] The imaging device 1c mounted on the headlight unit 801 in FIG. 8 has the first imaging unit 101 and the second imaging unit 102 of the imaging unit 100 installed at predetermined positions on the left and right of, for example, the light source device 800 on the installation surface 4. The optical axes (J1, J2) of the two cameras both face the Z direction. This imaging device 1 images the front of the vehicle with reference to the position of the headlight 203, enabling distance measurement and the like. In other words, this headlight 203 is a headlight equipped with a stereo camera function. Although not shown, the imaging unit 100 is connected to the processing device 3 in FIG. 1 in the same manner as in the first embodiment.

[0108] Then, the cover 2c is fixed on the installation surface 4 so as to cover the light source device 800 and the two imaging units. This cover 2c has an ellipsoidal surface shape in at least a part of the region, in the same manner as in the first embodiment. The relationship between the viewpoints (P1, P2) of the two cameras and the foci (F1, F2) of the cover 2c satisfies the coincidence condition, in the same manner as in the first embodiment. The imaging unit 100 may have a black-painted configuration, in the same manner as in the first embodiment (FIG. 5).

[0109] In FIG. 8, for example, the ray A1 shows an example of light incident from outside the cover 2c toward the first imaging unit 101. The ray A2 shows an example of light incident from outside the cover 2c toward the second imaging unit 102. The ray A3 shows an example of light reflected by the first imaging unit 101 and directed toward the inner surface of the cover 2c. The ray A4 shows an example of light that the ray A3 is reflected by the inner surface of the cover 2c and directed toward the second imaging unit 102. The ray A3 and the ray A4 have the property of being directed toward the camera viewpoints corresponding to the cover foci due to the ellipsoidal surface shape of the cover 2c, in the same manner as in the first embodiment.

[0110] According to the imaging device 1c of Embodiment 2, similar to Embodiment 1, due to the shape of the cover 2c, an effect of suppressing stray light as reflected light incident on the imaging unit 100 can be obtained. In the configuration of FIG. 8, the installation surface 4 is composed of a light reflecting member. Even in this case, due to the characteristics of the ellipsoidal surface of the cover 2, an effect of suppressing the reflected light incident on the imaging unit 100 can be obtained in the same manner as in Embodiment 1. In this configuration, when external light is incident on the installation surface 4 and reflected, even if the reflected light is further reflected by the cover 2, the reflected light does not face the lens (i.e., the entrance pupil) of the imaging unit 100.

[0111] As a modification of Embodiment 2, the imaging unit 100 in the headlight unit 801 is not limited to two cameras, and may be a combination of one camera and LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging), etc. For example, the second imaging unit 102 may be composed of LiDAR.

[0112] <Embodiment 3> The imaging device of Embodiment 3 will be described with reference to FIG. 9. Embodiment 3 shows a configuration example when the imaging device is installed as a security camera on the ceiling of a building or the like.

[0113] FIG. 9 shows a configuration example in which the imaging device 1d of Embodiment 3 is installed on the ceiling of a building as an object. In FIG. 9, an example of the positional relationship between the two cameras (the first imaging unit 101 and the second imaging unit 102) of the imaging unit 100 of the imaging device 1d, the cover 2d, and the installation surface 4 of the ceiling as the object is shown. In FIG. 9, the installation surface 4 of the ceiling is a horizontal plane which is the X - Y plane shown in the figure. With respect to this installation surface 4, the imaging device 1d is installed with the optical axis of the imaging unit 100 facing downward (Z direction). The imaging unit 100 and the cover 2d are fixed to the installation surface 4 of the ceiling.

[0114] In the example of FIG. 9, the field of view of each camera of the imaging unit 100 is set to a wide angle close to 180 degrees with respect to the optical axes (J1, J2). As a result, the common field of view by the two fields of view is also a wide angle close to 180 degrees with respect to the axis in the Z direction. Thus, this imaging device 1d can acquire an image with a wide field of view over the entire 360-degree circumference around the axis in the Z direction.

[0115] Within the cover 2d, the first imaging unit 101 and the second imaging unit 102 are installed at predetermined positions on the installation surface 4. The cover 2d has an ellipsoidal surface shape as in the first embodiment. The viewpoints (P1, P2) of the two cameras and the two foci (F1, F2) of the cover 2d satisfy the coincidence condition as in the first embodiment. The imaging unit 100 may have a blackened configuration as in the first embodiment (FIG. 5).

[0116] In this example, the installation surface 4 is part of the ceiling, but is not limited thereto. Similar to that described above (FIG. 3, etc.), the installation surface 4 may be the substrate 40 which is part of the imaging device 1d. Further, a light reflection suppressing member may be formed on the substrate 40. Also, in this example, with respect to the installation surface 4 which is the ceiling surface, the cover 2 is provided in a region roughly corresponding to a hemispherical region, and is provided in a region including a portion overlapping the fields of view of the two cameras.

[0117] Not limited thereto, the shape of the cover 2d may be such that a part thereof is cut out according to the shape of the object to be installed, such as a wall. A part of the cover 2d that interferes with a wall or the like may be cut out. Alternatively, when installed at a corner of a wall or the like, the cover 2d may be arranged over a region wider than a hemisphere.

[0118] According to the imaging device 1d of the third embodiment, similar to the first embodiment, due to the shape of the cover 2d, an effect of suppressing stray light as reflected light incident on the imaging unit 100 can be obtained.

[0119] As a conventional general shape of a cover for a security camera or the like, it is often a hemispherical shape. In this case, further, in the case of a structure such as a ceiling, for example, when there is an installation of a light emitter, an adoption of a shiny material, a painting with high brightness, etc., it causes external light to be reflected into the two cameras of the imaging unit. Therefore, conventionally, restrictions are also imposed on the designability of structures such as ceilings.

[0120] On the other hand, according to Embodiment 3, similar to Embodiment 1, due to the ellipsoidal surface shape of the cover 2d, the reflected light that causes external light to be reflected into one imaging unit is limited to only the light generated from the vicinity of the other imaging unit. Thus, in Embodiment 3, if a configuration is adopted in which the above-mentioned processing such as black painting for suppressing light emission and light reflection is performed only in the vicinity of the viewpoints (P1, P2) of the two cameras, it is possible to apply a free design to most of the structures such as ceilings.

[0121] <Embodiment 4> The imaging device of Embodiment 4 will be described with reference to FIG. 10. In each of the above-described embodiments, mainly, the positional relationship between the shape of the cover 2 and the imaging unit 100 has been described. Embodiment 4 corresponds to a modification of Embodiment 1, and particularly shows a configuration example regarding the thickness of the cover 2.

[0122] FIG. 10 shows a configuration example of the imaging unit 100 and the cover 2e in the imaging device 1e of Embodiment 4. In FIG. 10, in the X-Z cross-section, an example of the positional relationship between the two cameras of the imaging unit 100 and the cover 2e is shown. In FIG. 10, the outer surface of the cover 2e is denoted as the cover outer surface 2e1, and the inner surface of the cover 2 is denoted as the cover inner surface 2e2 and is illustrated. The light that is directly incident on the imaging unit 100 (for example, the second imaging unit 102), for example, the light ray A41, is shown. The light refracted by the cover 2e is shown as the light ray A42 as the cover refracted light.

[0123] [Comparative Example B] The cover of a general imaging device, for example, when it is a hemispherical cover, has a constant thickness. FIG. 15 shows an X-Z cross-sectional view of a configuration example of an imaging device 1B including a cover 2B having a general hemispherical shape with a constant thickness BT as a comparative example (referred to as Comparative Example B) for Embodiment 4. The X-Z cross-section of this cover 2B is semi-circular and has a radius BR. In this case, in this imaging device 1B, for example, a light ray B41 directed toward the second viewpoint BP2 of the second imaging unit B102 is refracted by the cover 2B as shown in the figure and becomes a light ray B42 as the cover-refracted light. However, the light ray B41 does not necessarily mean that the refracted light ray B42 is directed toward the second viewpoint BP2. Conversely, for example, as shown by the light ray B43, light directed toward, for example, the first viewpoint BP1 after refraction by the cover 2B was not necessarily light directed toward the first viewpoint P1 as the light ray B44 before refraction.

[0124] In this case, two viewpoints that are effective imaging unit viewpoints calculated with respect to the light before refraction vary depending on the angle of view of the subject. When the effective imaging unit viewpoints vary depending on the angle of view, for example, when the first imaging unit B101 and the second imaging unit B102, which are two cameras of the imaging unit, are a stereo camera, the baseline length BL varies. The baseline length BL is the distance between the effective imaging unit viewpoints of the two cameras. When the baseline length BL varies, the calculation of distance measurement based on the captured image becomes complicated.

[0125] Therefore, in Embodiment 4, as shown in FIG. 10, the cover 2e has a shape in which the thickness varies according to the position. As a result, light directly directed from the outside toward the imaging unit viewpoint, for example, the second viewpoint P2, for example, the light ray A41, and the light ray A42 after refraction by the cover 2e are also directed toward the second viewpoint P2. In other words, this cover 2e has a basic shape of a rotational ellipsoidal surface as shown in FIG. 3, for example, and the thickness corresponding to the position and location where each part of the cover 2e is provided is designed to reduce the influence of refraction as described above. This cover 2e is designed such that at each position, the light directed toward the imaging unit viewpoint before refraction is also directed toward the same imaging viewpoint after refraction.

[0126] Specifically, for the cover 2e in FIG. 10, it is required as a requirement that the thickness becomes smaller as the distance from the straight line 300 connecting the imaging unit viewpoints (the first viewpoint P1 and the second viewpoint P2), which is the rotation axis of the ellipsoidal shape, increases. In the example in FIG. 10, at the position of the distance h1 from the straight line 300, which is close to the center point of the cover 2e and has a large distance, the thickness is T1, and at the position of the distance h2 from the straight line 300, which is far from the center of the cover 2e and has a small distance, the thickness is T2. The thickness T1 is smaller than the thickness T2. In the direction (X direction) of the straight line 300 connecting the two imaging units (the first imaging unit 101 and the second imaging unit 102), the thickness (for example, thickness T1) at a position closer to the center of the cover 2 is smaller than the thickness (for example, thickness T2) at a position farther from the center of the cover 2.

[0127] In the case of the configuration in FIG. 10, either one or both of the outer surface 2e1 and the inner surface 2e2 of the cover 2e deviate from the exact ellipsoidal shape. However, even in this case, for example, the intermediate surface 1001 (illustrated by a broken-line curve) between the outer surface 2e1 and the inner surface 2e2 is made into the same ellipsoidal shape as in Embodiment 1. Thereby, the condition of coincidence that the respective foci of the outer surface 2e1 and the inner surface 2e2 coincide with the imaging unit viewpoints (P1, P2) or in the vicinity can be satisfied.

[0128] According to the imaging device 1e of Embodiment 4, similarly to Embodiment 1, due to the shape of the cover 2e, an effect of suppressing stray light as reflected light incident on the imaging unit 100 can be obtained. According to Embodiment 4, since the influence due to refraction in the cover 2e can be reduced, complication of the calculation of distance measurement based on the captured image can be avoided.

[0129] <Embodiment 5> The imaging device of Embodiment 5 will be described with reference to FIG. 11 and the like. In Embodiments 1 to 4 up to this point, configuration examples assuming a general camera as the imaging unit 100 and an accompanying optical system have been described. In contrast, Embodiment 5 shows a form in which a specific imaging unit is adopted.

[0130] FIG. 11 shows an example of the positional relationship between the imaging unit and the cover 2f in the imaging device 1f of Embodiment 5. The imaging device 1f in FIG. 11 is an imaging device including an imaging unit having a hyperbolic mirror, similar to the examples in FIGS. 5C and 7 of Patent Document 1.

[0131] [Comparative Example C] FIG. 16 shows an example of the positional relationship between the imaging unit and the cover 2C in the imaging device 1C of a comparative example (referred to as Comparative Example C) with respect to Embodiment 5 of FIG. 11. This imaging device 1C includes, as an imaging unit, an upper hyperbolic mirror CM1, a lower hyperbolic mirror CM2, a lens CL, and an image sensor CI. The lower hyperbolic mirror CM2 is further composed of a lower outer peripheral hyperbolic mirror CM21 and a lower inner peripheral hyperbolic mirror CM22. This imaging device 1C has an axially symmetric shape with, for example, the optical axis of the lens CL as the axis of symmetry (indicated by a one-dot chain line).

[0132] Also, in the configuration of Comparative Example C in FIG. 16, three points, namely, the entrance pupil of the lens CL, the outer focus of the lower outer peripheral hyperbolic mirror CM21, and the outer focus of the lower inner peripheral hyperbolic mirror CM22, are arranged to coincide. Further, the outer focus of the upper hyperbolic mirror CM1 and the focus of the lower inner peripheral hyperbolic mirror CM22 are arranged to coincide.

[0133] Of the light C30 from the subject C3, the light C32 traveling toward the focal point CF21 of the lower outer peripheral hyperbolic mirror CM21 is reflected by the lower outer peripheral hyperbolic mirror CM21 as shown in the figure, enters the lens CL, and is imaged on the image sensor CI. Here, since the imaged light C32 is the light traveling toward the focal point CF21 of the lower outer peripheral hyperbolic mirror CM21, the viewpoint of the imaged image is the focal point CF21. Similarly, of the light C30 from the subject C3, the light C32 traveling toward the focal point CF1 of the upper hyperbolic mirror CM1 is reflected by the upper hyperbolic mirror CM1 as shown in the figure and then travels toward the outer focal point of the upper hyperbolic mirror CM1 and the focal point of the lower inner peripheral hyperbolic mirror CM22. Then, the light traveling toward the focal point of the lower inner peripheral hyperbolic mirror CM22 is reflected again by the lower inner peripheral hyperbolic mirror CM22 and then travels toward the outer focal point of the lower inner peripheral hyperbolic mirror CM22, that is, the entrance pupil of the lens CL. These lights are imaged on the image sensor CI. Here, since the imaged light C31 is the light traveling toward the focal point CF1 of the upper hyperbolic mirror CM1, the viewpoint of the imaged image is the focal point CF1.

[0134] In this way, in the imaging unit having the configuration of Comparative Example C, one imaging unit consisting of a pair of the lens CL and the image sensor CI can acquire images from two viewpoints at 360 degrees around the entire circumference with respect to the symmetry axis (the Z-axis in this example). Such an imaging device contributes to simplification of the configuration and thus cost reduction.

[0135] The imaging device 1f of Embodiment 5 in FIG. 11 has the same configuration of the imaging unit as that of the imaging unit of Comparative Example C as described above, except for the cover 2f. In FIG. 11, the imaging device 1f includes, as the imaging unit 100 in FIG. 1, an upper hyperbolic mirror M1, a lower hyperbolic mirror M2, a lens 1101, and an image sensor 1102. The lower hyperbolic mirror M2 is further composed of a lower outer peripheral hyperbolic mirror M21 and a lower inner peripheral hyperbolic mirror M22. This imaging device 1f has an axially symmetric shape with, for example, the optical axis of the lens 1101 as the symmetry axis (indicated by a dashed-dotted line). The lens 1101 is disposed at the opening at the top of the upper hyperbolic mirror M1 on the symmetry axis, and the image sensor 1102 is disposed above the lens 1101 inside the upper hyperbolic mirror M1.

[0136] Also, the entrance pupil of the lens 1101, the outer focus of the lower outer peripheral hyperbolic mirror M21, and the outer focus of the lower inner peripheral hyperbolic mirror M22 are arranged to coincide, in other words, to satisfy the coincidence condition. Further, the outer focus of the upper hyperbolic mirror M1 and the focus of the lower inner peripheral hyperbolic mirror M22 are arranged to coincide, in other words, to satisfy the coincidence condition.

[0137] Of the light f30 from the subject f3, the light f32 heading towards the focus F21 of the lower outer peripheral hyperbolic mirror M21 is reflected by the lower outer peripheral hyperbolic mirror M21 as shown in the figure, enters the lens 1101, and forms an image on the image sensor 1102. Here, since the imaged light f32 is the light heading towards the focus F21 of the lower outer peripheral hyperbolic mirror M21, the viewpoint of the imaged image is the focus F21. Similarly, of the light f30 from the subject f3, the light f32 heading towards the focus F1 of the upper hyperbolic mirror M1 is reflected by the upper hyperbolic mirror M1 as shown in the figure and then heads towards the outer focus of the upper hyperbolic mirror M1 and the focus of the lower inner peripheral hyperbolic mirror M22. Then, the light heading towards the focus of the lower inner peripheral hyperbolic mirror M22 is reflected again by the lower inner peripheral hyperbolic mirror M22 and then heads towards the outer focus of the lower inner peripheral hyperbolic mirror M22, that is, the entrance pupil of the lens 1101. These lights form an image on the image sensor 1102. Here, since the imaged light f31 is the light heading towards the focus F1 of the upper hyperbolic mirror M1, the viewpoint of the imaged image is the focus F1.

[0138] When the correspondence of components is confirmed by comparing the configuration of Embodiment 5 in FIG. 11 with the configuration of Embodiment 1 in FIG. 3, it is as follows. For example, the first imaging unit 101 in FIG. 3 corresponds to the upper hyperbolic mirror M1, the lower inner peripheral hyperbolic mirror M22, the lens 1101, and the image sensor 1102 in FIG. 11. In other words, the components such as those hyperbolic mirrors M1 in FIG. 11 constitute the first imaging unit 101. Also, the second imaging unit 102 in FIG. 3 corresponds to the lower outer peripheral hyperbolic mirror M21, the lens 1101, and the image sensor 1102 in FIG. 11. In other words, the components such as those lower outer peripheral hyperbolic mirrors M21 in FIG. 11 constitute the second imaging unit 102.

[0139] In Comparative Example C of FIG. 16, the imaging device 1C has a cover 2C around the imaging unit with the optical axis of the lens CL as the central axis (target axis) so as to fix the imaging unit. The shape of the cover 2C is a cylindrical shape centered on the target axis, in other words, the shape of the side surface of a cylinder. As also shown in FIG. 16 and FIG. 7 of Patent Document 1, a cylindrical shape is considered as a general shape of the cover 2C in such an imaging device 1C.

[0140] In FIG. 16, in addition to the light C30 from the subject C3 which is the imaging target, an example of light from another subject C4 that causes stray light is shown. In the case of this Comparative Example C, for example, among the light from another subject C4, it has the light C41. The light C41 is the light that, after being reflected by the lower outer peripheral hyperbolic mirror CM21, is reflected again by the cover 2C and travels toward the focal point CF1 of the upper hyperbolic mirror CM1. This light C41 forms an image on the image sensor CI together with the light directly traveling from the subject C3 toward the focal point CF1 of the upper hyperbolic mirror CM1, and becomes stray light.

[0141] On the other hand, in the imaging device 1f of Embodiment 5 shown in FIG. 11, similar to Embodiment 1, the shape of the cover 2f is based on a rotational ellipsoidal surface shape. The cover 2f has a first focus F31 and a second focus F32 as the foci of the rotational ellipsoidal surface. In Embodiment 5, the positions of the two foci (F31, F32) of the cover 2f are made to coincide with the positions of the imaging unit viewpoints, that is, the focus CF1 of the upper hyperbolic mirror M1 and the focus CF21 of the lower outer peripheral hyperbolic mirror CM21. In other words, the two foci (F31, F32) of the cover 2f and the two foci (CF1, CF21) that are the imaging unit viewpoints are arranged so as to satisfy the above-described coincidence condition. As also shown in FIG. 11, the focus F31 is near the focus CF1, and the focus F32 is near the focus CF21.

[0142] With the above configuration, in the imaging device 1f, for example, the light that causes stray light reflected by the cover 2f and directed toward the focus CF1 of the upper hyperbolic mirror M1 is limited to only the light that exits from the focus CF21 of the lower outer peripheral hyperbolic mirror M21 and thus from the entrance pupil of the lens 1101.

[0143] The imaging device 1f of Embodiment 5, in consideration of the correspondence with the imaging device 1 of Embodiment 1, in other words, has the following configuration. The imaging device 1f includes an imaging unit and a light-transmissive cover 2f disposed in a region that intersects at least a part of the field of view of the imaging unit so as to accommodate the imaging unit. The cover 2f has a rotational ellipsoidal surface shape portion as a cover portion shaped to reflect light rays from a vicinity region of the first viewpoint of the imaging unit toward a vicinity region of the second viewpoint. The imaging unit has, as components, an upper hyperbolic mirror M1 (also referred to as a first reflection device), a lower outer peripheral hyperbolic mirror M21 (also referred to as a second reflection device), and a lower inner peripheral hyperbolic mirror M22 (also referred to as a third reflection device) on a first axis 1100 that serves as a rotation symmetry axis.

[0144] The upper hyperbolic mirror M1 is a first reflection device that reflects a first image from the focal point CF1 corresponding to the first viewpoint. The lower outer peripheral hyperbolic mirror M21 is arranged apart from the first reflection device (the upper hyperbolic mirror M1) and is a second reflection device that reflects a second image from the focal point CF21 corresponding to the second viewpoint. The lower inner peripheral hyperbolic mirror M22 is arranged concentrically with the second reflection device (the lower outer peripheral hyperbolic mirror M21) and is a third reflection device that reflects the first image reflected from the first reflection device (the upper hyperbolic mirror M1). The lens 1101 is arranged concentrically with the first reflection device (the upper hyperbolic mirror M1) and forms an image of an image including the first image reflected from the first reflection device and the third reflection device and the second image reflected from the second reflection device. The first reflection device (the upper hyperbolic mirror M1), the lens 1101, and the image sensor 1102 constitute a first imaging unit. The second reflection device (the lower outer peripheral hyperbolic mirror M21), the third reflection device (the lower inner peripheral hyperbolic mirror M22), the lens 1101, and the image sensor 1102 constitute a second imaging unit.

[0145] Also in Embodiment 5, similar to the above-described black coating configuration (FIG. 5), in the lens 1101, a configuration for suppressing reflected light, such as applying an antireflection coating, is provided. With this configuration, light generated from the position of the entrance pupil of the lens 1101 can be suppressed.

[0146] That is, by combining the configuration for limiting the optical path of stray light by the cover 2f and the configuration for suppressing reflected light of the lens 1101, it is possible to suppress the light that causes stray light toward the focal point CF1 of the upper hyperbolic mirror M1.

[0147] FIG. 12 shows a configuration example of suppressing reflected light such as black coating of the lens 1101. This lens 1101 has a cylindrical shape. A portion (in other words, the central axis portion) 1201 around the symmetry axis extending in the Z direction shown in the figure corresponding to the optical axis of the lens 1101 is a transmissive portion without providing a reflection suppression member. On the surface of the outer portion with respect to that portion 1201, a reflection suppression member such as an antireflection coating is provided. In this example, on the cylindrical surface of the lens 1101, a reflection suppression member is provided on the cylindrical portion of the side surface and the ring-shaped outer peripheral portion of the bottom surface. The light ray f5 is an example in which reflection is suppressed by the reflection suppression member on the surface of the lens 1101.

[0148] Also, in FIG. 12, an outline is shown regarding the above-described coincidence condition. The distance 1211 is the distance between the focal point CF1 of the upper hyperbolic mirror M1 and the focal point F31 of the cover 2f, and the distance 1212 is the scale of the lens 1101. The coincidence condition is that the distance 1211 is within the scale distance 1212.

[0149] Although not shown, as another comparative example, there is also a configuration in which a linear body is provided so as to extend from the center of the lower inner peripheral hyperbolic mirror toward the lens on the optical axis of the lens. In such a configuration, reflected light that does not cross the optical axis of the lens cannot be blocked. On the other hand, in the configuration of Embodiment 5, reflected light that does not cross the optical axis of the lens 1101 can also be suppressed.

[0150] Regarding the size of the cover 2f, as described in Embodiment 1, it is defined by the distance c between the first viewpoint P1 and the second viewpoint P2 which are the viewpoints of the imaging unit in FIG. 4, and the sizes (s1, s2) of the first imaging unit 101 and the second imaging unit 102 which are the imaging units 100 in FIG. 4. That is, in FIG. 11, the size of the cover 2f is defined by the distance fc between the focal point CF1 of the upper hyperbolic mirror M1 and the focal point CF21 of the lower outer peripheral hyperbolic mirror M21, and the size of the lens 1101 (distance 1212 in FIG. 12). In the case of Embodiment 5, as the size of the imaging unit, it is necessary to consider the sizes of the upper hyperbolic mirror M1 and the lower hyperbolic mirror M2.

[0151] When reducing costs in manufacturing the cover 2f, for example, injection molding of resin can be employed. Here, for example, when the shape of the cover 2f shown in FIG. 11, that is, generally a barrel shape, it may be difficult to manufacture the cover 2f in its original shape by injection molding. Therefore, the following methods can be adopted to facilitate the manufacturing by injection molding.

[0152] As shown in FIG. 13(A), there is a method of dividing the cover 2f of FIG. 11 by a line 1301 corresponding to the position of the most bulging part in the horizontal X and Y directions shown in the figure into an upper cover part 2fa and a lower cover part 2fb, and injection molding each of them. Note that the shape of this cover 2f can also be expressed as a shape obtained by removing the upper and lower parts, that is, the region where the hyperbolic mirror is arranged, from the rotational ellipsoidal surface around the axis of symmetry which is the rotation axis.

[0153] However, in this method, seams are generated in the horizontal X and Y directions at the location indicated by the line 1301 in the molded cover 2f. From the viewpoint of not crossing the horizontal seam of this cover 2f, when the subject moves in the horizontal direction, that is, when used for corresponding applications, this cover 2f is useful because it has a reflection light suppression effect.

[0154] On the other hand, as shown in FIG. 13(B), there is also a method of dividing the cover 2f into left and right parts by a line 1302 on a vertical plane including the optical axis (axis of symmetry) of the lens 1101 and injection molding each of them. In this method, seams are generated in the vertical Z direction at the location indicated by the line 1302 in the molded cover 2f. From the viewpoint of not crossing the vertical seam of this cover 2f, when the subject moves in the depth direction, that is, when used for corresponding applications, this cover 2f is similarly useful. Examples of such a moving subject include an obstacle falling on the road in front of the vehicle when this imaging device 1f is mounted on an automobile (for example, FIG. 2(A)).

[0155] According to the imaging device 1f of Embodiment 5, similar to Embodiment 1, due to the shape of the cover 2f, an effect of suppressing stray light as reflected light incident on the imaging unit 100 can be obtained. According to Embodiment 5, in the case of a configuration having a specific efficient imaging unit including a hyperbolic mirror, the influence of the reflected light by the cover 2f can be reduced, and the accuracy of distance measurement and the like can be improved.

[0156] As described above, the embodiments of the present disclosure have been specifically described, but the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist. Except for the essential components, the components can be added, deleted, replaced, etc. Unless otherwise specifically limited, each component may be singular or plural. A form combining each embodiment is also possible.

[0157] The present disclosure is not limited to the shape, dimensions, positional relationship, etc. of the components shown in the embodiments, and those substantially approximate or similar to the shape, etc. are also included in the scope of the present invention. For example, words representing the relationship, position, direction, shape, etc. of components, such as "horizontal", "vertical", "plane", "elliptical rotating surface", are not limited to the strict meaning of the words themselves, and as long as the object and effect of the present invention can be achieved, cases substantially the same as the meaning can also be included.

[0158] The embodiments of the present disclosure are not limited to a single implementation as an imaging device. In addition to implementation as a distance measurement device or the like, various aspects are possible, such as a vehicle equipped with an imaging device and construction equipment equipped with an imaging device.

Explanation of Reference Numerals

[0159] 1... Imaging device, 2... Cover, 4... Installation surface, 40... Substrate, 100... Imaging unit, 101... First imaging unit, 102... Second imaging unit, P1... First viewpoint, P2... Second viewpoint, F1... First cover focus, F2... Second cover focus, J1, J2... Optical axes, V1, V2... Fields of view, A1 to A4... Light rays.

Claims

1. An imaging device, comprising: a first imaging unit having a first viewpoint; and a second imaging unit having a second viewpoint; a light-transmissive cover disposed in a region that intersects at least a part of a first field of view of the first imaging unit and a second field of view of the second imaging unit so as to accommodate the first imaging unit and the second imaging unit; and the cover has a cover portion shaped to reflect light rays from a region near the first viewpoint toward a region near the second viewpoint and not to direct light rays other than those from the region near the first viewpoint toward the region near the second viewpoint. An imaging device.

2. The imaging device according to claim 1, wherein the shape of the cover portion is convex in a direction perpendicular to a straight line connecting the first viewpoint and the second viewpoint. An imaging device.

3. The imaging device according to claim 1, wherein the shape of the cover portion is an ellipsoidal of revolution shape. An imaging device.

4. The imaging device according to claim 3, wherein the first imaging unit, the second imaging unit, and the cover are arranged so as to satisfy a condition that, for a first focus and a second focus that are two foci of the ellipsoidal of revolution shape of the cover portion, the first focus coincides with the first viewpoint and the second focus coincides with the second viewpoint; the coincidence condition is that, when a distance between the first focus and the first viewpoint is d1, a distance between the second focus and the second viewpoint is d2, a size of the first imaging unit is s1, and a size of the second imaging unit is s2, d1 ≤ s1 and d2 ≤ s2. An imaging device.

5. The imaging device according to claim 1, wherein the cover is provided in a hemispherical region on an installation surface on which the first imaging unit and the second imaging unit are installed; the installation surface includes a substrate on which the first imaging unit and the second imaging unit are installed and which is connected to the cover. An imaging device.

6. The imaging device according to claim 1, wherein the first imaging unit and the second imaging unit each have a lens, and a light reflection suppressing member is provided in a portion of the space inside the cover that is exposed other than the lens. An imaging device.

7. The imaging device according to claim 1, wherein the imaging device is installed or incorporated in a vehicle headlight; the headlight includes a light source on an installation surface, and a light-reflective member is provided around the light source; the first imaging unit and the second imaging unit are installed on the installation surface of the headlight, and the cover is connected thereto. An imaging device.

8. In the imaging device according to claim 1, Installed or built-in on the ceiling or wall of a building, On the installation surface of the ceiling or wall, the first imaging unit and the second imaging unit are installed, and the cover is connected, Imaging device.

9. In the imaging device according to claim 8, The cover is provided in a hemispherical region on the installation surface where the first imaging unit and the second imaging unit are installed, As the installation surface, a substrate on which the first imaging unit and the second imaging unit are installed and which is connected to the cover is provided, The substrate is provided with a light reflection suppressing member on a portion exposed to the space inside the cover on the surface where the first imaging unit and the second imaging unit are installed, Imaging device.

10. In the imaging device according to claim 1, The shape of the cover portion is such that the light that was directed toward the viewpoint of the imaging unit before refraction at the cover portion as light from outside the cover is also directed toward the viewpoint of the imaging unit after refraction at the cover portion, having different thicknesses for each position, Imaging device.

11. In the imaging device according to claim 1, The first imaging unit and the second imaging unit are a stereo camera, Imaging device.

12. In the imaging device according to claim 11, A processing device for measuring the distance to a subject based on a first image acquired from the first imaging unit and a second image acquired from the second imaging unit is provided, Imaging device.

13. An imaging unit, A light-transmissive cover disposed in a region intersecting at least a part of the field of view of the imaging unit so as to accommodate the imaging unit, Comprising, The imaging unit is, On a first axis that is a rotation symmetry axis corresponding to the optical axis of the lens, A first reflection device that has a first focal point and reflects a first image that is light directed toward a first viewpoint corresponding to the first focal point, A second reflection device that is disposed apart from the first reflection device, has a second focal point, and reflects a second image that is light directed toward a second viewpoint corresponding to the second focal point, A third reflection device that is disposed concentrically with the second reflection device and reflects the first image reflected from the first reflection device, A lens that is disposed concentrically with the first reflection device and forms an image of an image including the first image reflected from the first reflection device and the third reflection device and the second image reflected from the second reflection device, An image sensor that acquires the image formed by the lens, Having, The cover has a cover portion shaped to reflect light rays from the vicinity of the first viewpoint of the imaging unit toward the vicinity of the second viewpoint and shaped such that light rays other than those from the vicinity of the first viewpoint do not travel toward the vicinity of the second viewpoint. An imaging device.

14. In the imaging device according to claim 13, the first reflection device, the second reflection device, and the third reflection device are each a hyperbolic mirror. An imaging device.

15. As an imaging unit, a first imaging unit having a first viewpoint and a second imaging unit having a second viewpoint, a light-transmissive cover disposed in a region that intersects at least a part of the first visual field of the first imaging unit and the second visual field of the second imaging unit so as to house the first imaging unit and the second imaging unit, and the cover has a cover portion shaped to reflect light rays from the vicinity of the first viewpoint toward the vicinity of the second viewpoint, the shape of the cover portion is an ellipsoidal of revolution shape, the first imaging unit, the second imaging unit, and the cover are arranged so as to satisfy the condition that, for the first focus and the second focus that are the two foci of the ellipsoidal of revolution shape of the cover portion, the first focus coincides with the first viewpoint and the second focus coincides with the second viewpoint, the coincidence condition is that, when the distance between the first focus and the first viewpoint is d1, the distance between the second focus and the second viewpoint is d2, the size of the first imaging unit is s1, and the size of the second imaging unit is s2, d1 ≤ s1 and d2 ≤ s2. An imaging device.

Images