JP2019185012A - Imaging device - Google Patents

Abstract

To provide an imaging device which can be configured easily and inexpensively to be small and light-weight, capable of performing imaging with high accuracy and high quality through a reflection optical system even in environment in which a large temperature distribution may occur.SOLUTION: An imaging optical system 101 of a stereo imaging device 100 comprises: a plurality of mirrors R2-R6 held by lens barrel members U1 and U2; and imaging elements 105L and 105R receiving photographic light sequentially reflected by the mirrors. The imaging optical system 101 is stored in a case 102 and the case 102 is stored in a case 103. Support members 107 are arranged between the imaging optical system 101 and the inner case 102 and between the inner case and the outer case 103 and the members are separated so as not to be brought into surface contact with each other. In order to make coefficient of thermal conductivity of the case 102 larger than that of the case 103, for example, material such as metal is used for the case 102 and such as resin for the case 103.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a photographing apparatus using a reflective optical element in a photographing optical system.

  A wide-angle lens used in an imaging device such as a camera mounted on a moving body such as a surveillance camera or a car is desired to have a wide field of view, a compact, lightweight, and highly accurate distance measurement. In the case where a refractive optical system is used for the photographing optical system, for example, a configuration is known in which various optical systems having a two-group configuration that requires as few lenses as possible are combined with an image sensor. Further, a configuration in which a reflection optical system instead of a refractive optical system is used for the photographing optical system is also conceivable.

  On the other hand, when the reflection optical system is used for the photographing optical system, there is an advantage that there is no chromatic aberration and the common optical system can cope with visible light to infrared light. As an imaging device that combines an imaging element and a reflective optical unit, a configuration as shown in Patent Document 1 below is known. In Patent Document 1, an optical unit in which a plurality of reflecting surfaces are formed on the surface of a lens barrel member is disclosed as a method for realizing a small stereo camera while ensuring the accuracy of distance measurement.

JP-A-7-168010

  In a system using an in-vehicle imaging device, a configuration in which a stereo camera having an imaging device and two imaging optical systems on the left and right sides is installed in a driver's cab and the distance to an object in the field of view is measured while taking an image. Are known. The measured distance information is used for driving support and driving control. For example, in driving assistance, the measured distance information is notified to the driver, and in driving control, the measured distance information is combined with the result of image recognition, etc. to avoid obstacles or automatically brake. Various embodiments are possible.

  In general, in an imaging apparatus that performs stereo imaging, the distance is calculated from the parallax amounts of two images of the same object obtained through both the left and right imaging optical systems using the principle of triangulation. In particular, in-vehicle imaging devices such as those described above require an optical system with higher accuracy than a camera intended for simple image acquisition.

  In addition, an in-vehicle imaging device used by being mounted on a vehicle is required to operate properly even if it is exposed to severe environmental conditions with respect to ambient temperature and the like. For example, when an imaging device is installed near the ceiling of a driver's cab, a room mirror, or the like, a large temperature distribution may occur around the imaging device. In such an installation position, for example, there may be an operating environment in which direct sunlight and cold air from a cooling device are exposed simultaneously.

  When an optical unit as shown in Patent Document 1 is used for such an in-vehicle imaging device, it is conceivable that a large temperature difference occurs in each part inside the imaging device. Due to this, there is a difference in the amount of thermal expansion of each part, and for example, the surface accuracy of the mirror and the positional accuracy between the plurality of mirror surfaces are affected, and there is a possibility that the ranging accuracy will be lowered. In various electronic devices whose temperature conditions should be strictly managed, a configuration in which temperature management is positively performed using a constant temperature device, a cooling (heating) device, or the like is used. However, in many cases, it is difficult to adopt such a configuration for active temperature management in consideration of cost, installation space, operation noise, and the like in a vehicle-mounted imaging device. The above-described problems relating to the temperature condition are the same even in the case of a monocular imaging device that is not a stereo imaging device.

  SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide an imaging apparatus that can be configured with a simple, low cost, small size and light weight that can perform high-accuracy and high-quality imaging via a reflective optical system even in an environment where a large temperature distribution occurs. There is.

  In a photographing apparatus having a photographing unit including a plurality of reflective optical elements provided on a base material and an imaging element that receives photographing light sequentially reflected by the plurality of reflective optical elements, the photographing unit is accommodated. The imaging apparatus includes a first container and a second container that houses the first container, and the thermal conductivity of the first container is higher than the thermal conductivity of the second container.

  According to the above configuration, for example, in an in-vehicle environment, an excellent imaging device that can perform high-accuracy and high-quality imaging via a reflective optical system even in an environment where a large temperature distribution occurs, and that can be configured simply and inexpensively is provided. can do.

It is sectional drawing of the imaging optical system of the stereo imaging device of embodiment which concerns on this invention. It is explanatory drawing which showed the cross-section of the stereo imaging device which concerns on this invention. It is explanatory drawing which showed the stereo imaging device which concerns on this invention by the perspective from the upper direction. It is explanatory drawing which showed the internal structure of the stereo imaging device which concerns on this invention by the exploded perspective view. (A) It is explanatory drawing which showed the structure of the supporting member of the case of the stereo imaging device which concerns on this invention. (B) It is explanatory drawing which showed the structure from which the support member of the case of the stereo imaging device which concerns on this invention differs. (C) It is explanatory drawing which showed the further different structure of the supporting member of the case of the stereo imaging device which concerns on this invention. It is sectional drawing which showed one embodiment of the support method of the imaging optical system of the stereo imaging device which concerns on this invention. It is explanatory drawing which showed the stereo imaging device which concerns on this invention by the perspective from the downward direction. (A), (b) is explanatory drawing of the motor vehicle which mounted the stereo imaging device of embodiment as a vehicle-mounted imaging device.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In addition, the structure shown below is an example to the last, For example, it can change suitably for those skilled in the art in the range which does not deviate from the meaning of this invention about a detailed structure. Moreover, the numerical value taken up by this embodiment is a reference numerical value, Comprising: This invention is not limited.

  In the following, a photographing provided with mirrors (R1 to R6) as a plurality of reflective optical elements provided on a base material and imaging elements (IMG1, IMG2) that receive photographing light sequentially reflected by these mirrors. The structure of the imaging device which has a part (imaging optical system STU: FIG. 1) is illustrated. In the photographing unit of this photographing apparatus, an off-axial imaging optical system is configured by the mirrors (R1 to R6), and this photographing optical system does not have a refractive optical element.

  In addition, the imaging unit (imaging optical system STU: FIG. 1) of the present embodiment is configured as a stereo camera. That is, the imaging unit (imaging optical system STU: FIG. 1) includes first and second reflection optical systems (LO1, LO2: imaging optics) each having a plurality of mirrors (R1 to R6) having different imaging optical axes. System). The photographing light reflected through the first and second reflective optical systems is imaged by the first and second imaging elements (IMG1, IMG2), respectively.

  In addition, an imaging apparatus (100: FIGS. 2 to 4, 800: stereo imaging apparatus of FIG. 8) provided with the imaging unit (imaging optical system STU: FIG. 1) can be mounted on a vehicle such as an automobile (FIG. 8). Configured as an in-vehicle imaging device. In that case, the image data obtained by, for example, stereo photographing by the photographing apparatus (100) and the analysis result thereof can be used for vehicle control and driving support.

  FIG. 1 schematically shows a cross-sectional configuration of an imaging optical system used in the stereo photographing optical system according to the present embodiment. In this embodiment, from the object side (subject side) to the image side (image plane side formed on the image sensor), the center of the image plane passes from the center of the object plane (not shown) through the center of the pupil (aperture). Is defined as a central chief ray or a reference axis ray. In FIG. 1, this central principal ray or reference axis ray is indicated by a one-dot chain line. Hereinafter, the path along which the central principal ray or the reference axis ray passes may be simply referred to as “reference axis”.

  In FIG. 1, reference numerals such as SP1, SP2, R1 to R6 are used for the optical functional parts. R1 and R2 are openings (apertures) into which the left and right stereo photographing light is incident, and in this example also serve as a diaphragm surface. The openings SP1 and SP2 that are spaced apart in the left-right direction in the drawing constitute a so-called parallax in the stereo measurement system, and the distance may be referred to as a baseline length.

  In FIG. 1, R2 to R6 are mirrors that respectively constitute the left and right imaging optical systems LO1 and LO2 in a stereo configuration. The reflecting surfaces of the mirrors are the reflecting surface tilted with respect to the openings SP1 and SP2 (R1), the third surface (R3), the fourth surface (R4), and the fifth surface (R5). ), And the sixth surface (R6) is a reflective surface shifted and tilted with respect to each of the preceding reflective surfaces. The reflecting surface of each mirror from the second surface (R2) to the sixth surface (R6) is made of metal, glass, plastic, or the like. As the reflecting surface, a known reflecting film made of aluminum, silver, chromium or the like can be used. From the viewpoint of reflectivity, a reflective film of aluminum or silver, more preferably silver can be used. The mirrors R2 to R6 constituting the second surface to the sixth surface have a combination of concave or convex surfaces, and the imaging optical systems LO1 and LO2 made of these are preferably about 60 ° to 70 ° or more, for example. It is configured as a wide-angle system having an angle of view.

  The imaging optical system (LO1, LO2) of the present embodiment has a reference wavelength optical path (reference axis) from the object plane to the image plane, and a curved surface (Off−) where the surface normal of the reflecting surface does not coincide with the reference axis. This is an off-axial optical system (off-axial optical system) including an axial curved surface. In this photographing optical system, the reflecting surfaces constituting the imaging optical systems LO1 and LO2 do not have a common optical axis. Therefore, in the present embodiment, an optical coordinate system is set in which the center position of the openings SP1 and SP2 (R1) is the origin position. That is, a path followed by a ray (central principal ray or reference optical axis) passing through the origin position of the optical coordinate system, which is the center of the openings SP1 and SP2 (R1), and the center position of the final imaging plane (imaging element surface). Reference axis. Furthermore, the reference axis has a direction (orientation). The direction is the direction in which the central principal ray or the reference axis ray travels in the image plane direction.

  In the imaging optical system of the present embodiment, the central principal ray or the reference axis ray is reflected by each reflecting surface before passing through the center point (origin) of the openings SP1 and SP2 (R1) and reaching the center of the final imaging plane. To do. The order of each surface is set so that the central principal ray or the reference axis ray is reflected. For this reason, the reference axis finally reaches the center of the image plane of the image sensors IMG1 and IMG2 while changing the direction in accordance with the law of reflection along the set order of each plane. In the present embodiment, the image side or object side means which side is the direction of the reference axis.

  In this example, the reference axis serving as the reference for the imaging optical system is set as described above. However, the method for determining the reference axis is arbitrary, and each surface-shaped optical component that constitutes the imaging optical system. A convenient setting may be adopted in consideration of design, aberration calculation, and ray tracing for that purpose. In general, the ray traces that pass through the center of the image plane, the stop or entrance pupil or exit pupil, or the openings SP1 and SP2 (R1) of the imaging optical systems LO1 and LO2 and the center of the final plane. The route should be set as the reference axis.

  The stereo photographing optical system including the imaging optical systems LO1 and LO2 of the present embodiment is configured based on the following considerations.

  2. Description of the Related Art Conventionally, an optical system for use in an in-vehicle camera has been known in which a distance is measured or a 3D shape is acquired by horizontally observing two transmissive refractive optical systems using lenses and viewing them in stereo. In addition, various small-sized and high-quality photographing optical systems using an imaging optical system including a rotationally asymmetric reflecting surface have been proposed. In order to measure a distance with high accuracy using a stereo photographing optical system or to acquire a 3D shape, it is necessary to improve the imaging performance and improve the image quality. In addition, in the distance measurement application with an in-vehicle camera, it is necessary to capture the surroundings widely, and thus it is necessary to widen the angle of view to some extent. In addition, in a vehicle environment where the temperature tends to fluctuate up and down depending on the external environment, if the imaging performance is greatly changed due to the temperature change, the distance measurement accuracy may be deteriorated. Therefore, it has been desired that there is little change in imaging performance due to temperature.

  In addition, in the case of simple enhancement of sensitivity, it is difficult to measure the distance at night only in the visible light region due to the influence of noise and the like, and it is desired that not only the visible light region but also the near infrared light region can be imaged. The visible light region refers to a wavelength region having a wavelength of about 380 nm to 700 nm, and the near infrared light region is a wavelength region of about 700 nm to 1500 nm. When handling imaging light in such a wavelength range, an imaging optical system having a relatively bright F value of about F2 to 4 is desired because of the diffraction limit.

  In addition, when a stereo photographing optical system that satisfies the above-described requirements is configured by a transmissive lens optical system, generally a high-quality photographing optical system with a wide angle and a bright F value can be obtained by increasing the number of lenses. However, such a refracting optical system has a problem in that the number of parts is greatly increased, resulting in an increase in cost, and manufacturing errors and assembly errors must be suppressed. Furthermore, manufacturing costs are still increased in order to adjust the positions of the two optical systems with high accuracy for stereo viewing.

  On the other hand, the stereo imaging optical system of the present embodiment has at least one mirror (common to both optical systems) in which each of the two imaging optical systems has a plurality of reflecting surfaces, and each of the reflecting surfaces has a surface. A cylindrical member is provided. In particular, the reflecting optical element constituting the plurality of reflecting surfaces is a mirror, and more preferably a hollow mirror structure in which the reflecting surface is formed on the surface of the lens barrel member, so that it is not necessary to correct chromatic aberration and the number of components is small. F-number is bright and high imaging performance can be obtained. In addition, since the reflecting surface is integrally formed and arranged on the surface of the lens barrel member, it is possible to reduce deterioration in imaging performance due to manufacturing errors.

  Here, the hollow mirror configuration refers to a mirror structure in which a reflecting surface is coated with a material having a high reflectance in the visible light region or the infrared region, such as silver or aluminum (a method such as vapor deposition is arbitrary). That is, in the hollow mirror configuration, the incident side and the emission side (reflection side) of the reflection surface are both a gas medium such as air or a vacuum.

  That is, the reflective optical element of the present embodiment is not configured to propagate light in a transparent solid medium such as a prism and reflect it on the wall surface (or the boundary with the outside world). If an element such as a prism is used as the reflective optical element, it will cause chromatic aberration, which is not preferable.

  In the present embodiment, at least one of the plurality of reflecting surfaces constituting the first imaging optical system and at least one of the plurality of reflecting surfaces constituting the second imaging optical system are the same surface of the lens barrel member. Is formed. Thus, by using the same and common lens barrel member, the two optical axes of the stereo image forming optical system can be positioned extremely easily. By using the same and common lens barrel members, that is, by forming at least a part of the first imaging optical system and at least a part of the second imaging optical system integrally, the two imaging optical systems The alignment error can be greatly reduced.

  The material of the lens barrel members U1 and U2 is not particularly limited, and for example, a metal or resin can be the main component. It is preferable to use a metal as a main component because it is a good heat conductive material. The metal here is not limited to a so-called pure metal, but may be an alloy, for example. If a lightweight metal alloy such as an aluminum alloy or a magnesium alloy is used, there is an advantage that the frame and the support base can be manufactured at low cost, light weight and high rigidity. Furthermore, when a magnesium alloy is used, it is possible to manufacture a metal barrel member with higher accuracy by the thixomold method, which is advantageous for improving the accuracy (surface accuracy and position accuracy) of the reflecting surface. It is. Moreover, if it is resin, it can select from a thermosetting resin, a thermoplastic resin, an ultraviolet curable resin, etc. in view of easiness of shaping | molding, durability, etc. For example, polycarbonate resin, acrylic resin, MS resin, polyolefin resin, or the like can be used. In particular, since the polyolefin resin has low hygroscopicity, it is possible to provide a reflective optical unit that can suppress volume change due to moisture absorption of the resin and realize high ranging accuracy without being affected by the humidity environment in which the unit is used. As a specific example of the polyolefin-based material, for example, ZEONEX (registered trademark) manufactured by ZEON CORPORATION can be used. Moreover, it is not necessarily composed of a single material, and it is possible to use a material in which inorganic fine particles or the like are dispersed in order to improve the properties and impart functions of the material. Moreover, you may be comprised from the several layer from which material differs.

  Furthermore, in the imaging apparatus according to the present embodiment, the selection of the image sensor, for example, for the far infrared light region, for example, selecting the image sensor for thermography having a wavelength of 3 μm to 17 μm, etc. External light imaging can also be performed. If you are going to shoot far-infrared light in stereo shooting using a refractive optical system that includes lenses and prisms, you need to change the lens material from glass to germanium, and so on. .

  As described above, in the present embodiment, by configuring the stereo photographing optical system with the hollow mirror configuration as described above, it is possible to cope with the same stereo photographing optical system from the visible light region to the far infrared light region. For example, using the same imaging optical system, changing only the type of image sensor, and lineup of different products that perform stereo shooting in the visible light region and the far-infrared light region, the manufacturing costs for each are significantly increased. It can be kept low.

  Based on the above circumstances, the configuration of the imaging optical system STU (imaging unit) in FIG. 1 will now be described in more detail. As shown in FIG. 1, the photographing optical system STU includes a first imaging optical system LO1 and a second imaging optical system LO2 each having a plurality of reflecting surfaces. The first and second imaging optical systems LO1 and LO2 have first and second openings SP1 and SP2 on the most object side. The first and second imaging elements IMG1 and IMG2 are arranged on the imaging surfaces of the first and second imaging optical systems LO1 and LO2, respectively. Here, the plurality of reflecting surfaces (R2 to R6) of the photographing optical system STU are formed on the surfaces of the lens barrel members U1 and U2 constituting the base material of the photographing optical system STU.

  In FIG. 1, photographing light enters from two openings SP1 and SP2 of the imaging optical systems LO1 and LO2. Then, the light is sequentially reflected by each mirror constituting the plurality of reflecting surfaces of the second surface (R2) to the sixth surface (R6) of the imaging optical system LO1 and the imaging optical system LO2, and is connected to the image sensors IMG1 and IMG2, respectively. Image. The positions of the openings SP1 and SP2 correspond to the positions of the entrance pupils of the imaging optical systems LO1 and LO2 configured by the mirrors of the second surface (R2) to the sixth surface (R6). In FIG. 1, the reflecting surfaces of the second surface (R2) to the sixth surface (R6) constituting the imaging optical system LO1 and the imaging optical system LO2, respectively, are configured in a rotationally asymmetric shape, for example. The imaging optical systems LO1 and LO2 are configured as an off-axial optical system (off-axial optical system) in which the reference axis is bent as illustrated.

  In the above stereo imaging optical system, in order to calculate the distance from two images after shooting (imaging) using the stereo imaging optical system, the arrangement accuracy of the reflecting optical elements of the two imaging optical systems greatly affects. . Reflective optical systems are advantageous for miniaturization and high performance of imaging performance, while the problem of high sensitivity of manufacturing errors in one imaging optical system and the precise arrangement of two imaging optical systems in stereo. There are two issues that need to be done.

  Therefore, in the present embodiment, as shown in FIG. 1, a plurality of reflecting surfaces constituting the first imaging optical system LO1 are integrally formed so as to constitute the photographing optical system STU, respectively. The structure is formed on the surface of U2. That is, among the plurality of reflecting surfaces constituting the first imaging optical system LO1, the lower reflecting surface (R3) and R5 in FIG. 1 are formed on the surface of the barrel member U1. Further, the upper reflecting surface (R2), R4, and R6 in FIG. 1 are formed on the surface of the barrel member U2. In addition, a plurality of reflecting surfaces constituting the second imaging optical system LO2 are formed on the surface of the barrel member U1 or U2 constituting the photographing optical system STU. That is, among the plurality of reflecting surfaces constituting the second imaging optical system LO2, the reflecting surface (R3) and R5 on the lower side in FIG. 1 are formed on the surface of the barrel member U1. Further, the upper reflecting surface (R2), R4, and R6 in FIG. 1 are formed on the surface of the barrel member U2. In the present embodiment, reflection surfaces (R3, R5) in the first and second imaging optical systems are formed on the surface of the first lens barrel member U1. Further, reflection surfaces (R2, R4, R6) in the first and second imaging optical systems are also formed on the surface of the second lens barrel member U2. With such a configuration, the work of adjusting the mutual positional relationship between the two imaging optical systems LO1 and LO2 that perform stereo shooting is basically unnecessary.

  With the above configuration, the above two problems can be solved. The first imaging optical system LO1 and the second imaging optical system LO2 have a plurality of reflecting surfaces having rotationally asymmetric curvatures in order to bend the reference axis. By having such a reflective surface, aberration correction can be facilitated and imaging performance can be improved.

  In addition to the visible light (wavelength: 380 nm to 700 nm), the imaging elements IMG1 and IMG2 for stereo photography also receive light in a wavelength band different from visible light (for example, near-infrared region near 1000 nm) and receive it as an electrical signal. It is more preferable if it can be converted. In the case of an imaging optical system in which an optical surface having imaging and condensing power (optical power) is configured only by a reflective surface as in the present embodiment, there is no chromatic aberration, and thus an imaging configured by a refractive optical system. High imaging performance can be maintained in a wider wavelength band than the optical system. Therefore, information other than visible light can be acquired simultaneously using the same optical system simply by expanding the light receiving wavelength range of the image sensor. For this reason, it is possible to reduce the size of the photographing system as compared with a camera system in which an infrared camera device is separately mounted.

  Further, the lens barrel that holds the first and second imaging optical systems (LO1 and LO2) preferably has a configuration that can also hold the imaging elements IMG1 and IMG2. According to such a configuration, since the imaging device can be fixed to the lens barrel as it is, the alignment work between the two imaging optical systems (LO1 and LO2) and the respective imaging devices is basically unnecessary, and thereby the assembly process. This is advantageous in terms of manufacturing cost.

  The configuration of the imaging unit (imaging optical system (LO1 and LO2) of the present embodiment has the above-described advantages. Hereinafter, an automobile is used for the purpose of vehicle control and driving support, particularly using the above-described imaging unit. An example of a configuration suitable as a vehicle-mounted imaging device mounted on a vehicle such as is shown.

  1 to 4 show a configuration example of a stereo imaging device 100 configured as an in-vehicle imaging device according to the present embodiment. 1 to 4 can be mounted on a moving body such as an automobile as the stereo imaging device 800 in the manner shown in FIGS. 8A and 8B, for example.

  FIGS. 8A and 8B show an example in which a stereo photographing apparatus 800 configured similarly to the stereo photographing apparatus 100 of FIGS. 1 to 4 is mounted on a vehicle as an in-vehicle photographing apparatus. In FIG. 8, a stereo photographing apparatus 800 can be mounted inside the windshield 1001 (wind shield) of the automobile 1000 and on the side of the passenger compartment 1002 as shown in FIGS. 8 (a) and 8 (b). In the example of FIGS. 8A and 8B, any automobile 1000 is mounted on the ceiling in the passenger compartment 1002 near the upper edge of the windshield 1001. For example, even if the stereo photographing apparatus 800 is an automobile 1000 having a roof on the upper part of the passenger compartment 1002 as shown in FIG. 8A, the automobile 1000 with the upper part of the passenger compartment 1002 opened as shown in FIG. It can be installed in any of the so-called open cars. For example, the stereo photographing apparatus 800 can be suitably mounted on the windshield 1001 or the inner surface of the ceiling in the vicinity thereof.

  In order to enhance automatic driving and driving support, if it is necessary to measure the distance from another vehicle that travels behind using the stereo photographing apparatus 800 or the distance from an object when reversing, the stereo photographing apparatus 800 is used. May be mounted inside the rear glass. As will be described later, the stereo photographing apparatus of the present embodiment is configured to be able to satisfactorily suppress a reduction in photographing accuracy or measurement accuracy due to direct sunlight, cold air, etc., and is reliable regardless of the position of the vehicle. High measurement results can be obtained.

  When the stereo photographing apparatus 800 is mounted on a vehicle as an in-vehicle photographing apparatus in a manner as shown in FIG. 8, the surrounding temperature environment may be quite severe for an electronic device. For example, when it is placed under a hot summer sun, it may be exposed to sunlight (direct sunlight) through the windshield 1001, and interior items such as dashboards in the vehicle may become hot. In the case of a dashboard, the surface temperature may reach about 120 ° C. by irradiation with sunlight (direct sunlight). In addition, the atmospheric temperature in the vehicle compartment at that time becomes a high temperature of about 75 ° C. unless air-conditioning is performed.

  As shown in FIG. 2, sunlight (direct sunlight) is irradiated above the windshield 1001 side of the stereo photographing apparatus. On the other hand, if the driver or passenger is in the passenger compartment and the air conditioner is activated by turning on the engine of the car, for example, the wind of the air conditioner that is about 25 ° C. from the lower part of the vicinity of the room mirror where the stereo photographing device is installed. You will win.

  When the imaging apparatus is placed in such a temperature environment having a large temperature difference, the optical system may be thermally deformed due to the temperature difference, and the optical performance may be affected. In particular, in the stereo photographing optical system as in the present embodiment, it becomes a big problem that the deformation becomes non-uniform due to the temperature unevenness of the environmental temperature. Therefore, it is necessary to keep the temperature around the optical system uniform.

  In the stereo photographing apparatus 100 (FIGS. 2 to 4) of the present embodiment, the photographing unit (the photographing optical system 101: the imaging optical system (LO1 and LO2)) is housed in a first container, and further the first The container (case 102) is accommodated in the second container (case 103), and the thermal conductivity of the first container (102) and the thermal conductivity of the second container (103) are different from each other. The first container (102) has a higher thermal conductivity than the second container (103).

  In FIG. 2, the photographing optical system 101 corresponds to the imaging optical systems LO1 and LO2 in FIG. The position of each mirror is schematically indicated by a thick black line in the figure. The image sensors IMG1 and IMG2 are shown as the image sensor 105 in FIG. The signal lines of the image sensor 105 are led out from the cases 102 and 103 and connected to the main board 106 attached to the exterior member 104 that holds the case 103. The main board 106 is wired to a control device (not shown) that performs driving support and driving control mounted on the vehicle.

  In particular, when it is necessary to mount a member that generates a large amount of heat during operation on the circuit on the main board 106, the configuration shown in FIG. 2 is effective. That is, the main board 106 is not arranged in the vicinity of the image sensors IMG1 and IMG2 inside the cases 102 and 103 but outside the case 103. Thereby, the main substrate 106 can be isolated so that the amount of heat generated by the main substrate 106 does not affect the optical elements (mirrors) of the photographing optical system 101 and the imaging elements IMG1 and IMG2.

  If the stereo photographing apparatus 100 is mounted on a vehicle, the stereo photographing apparatus 100 is mounted on a predetermined mounting position of the vehicle, for example, near a front window, near a room mirror, or the like via an exterior member 104. The exterior member 104 functions as a mounting portion (mount member) for mounting the stereo imaging device 100 on the vehicle. Note that the exterior member 104 as the mounting portion may have a structure such as a support or a bracket.

  Note that when the material of the exterior member 104 has a high thermal conductivity such as metal and has a heat dissipation composition, a heat conductive material such as a heat sink is disposed between the main board 106 and the exterior member 104. Can do. As a result, the amount of heat generated in the main board 106 during operation can be released to the exterior member 104 side.

  In FIG. 2, the satin portion shown as the photographing optical system 101 substantially corresponds to the cross-sectional shape viewed from the side of the barrel member U1 or U2 in FIG. By adopting a double structure in which the photographing optical system 101 is accommodated in the first container (case 102) and the second container (case 103), the influence of the temperature distribution around the stereo photographing apparatus 100 can be reduced. it can. With this configuration, it is possible to reduce the influence of the temperature distribution on the part of the imaging optical system 101 without using a separate fan, cooling, heating, etc. Therefore, it is possible to provide a high-accuracy photographing optical system at a low cost without being influenced by the above.

  In the stereo imaging device 100 of FIG. 2, the imaging optical system 101 is held by the inner case 102 via the support member 107. The case 102 is held by the outer case 103 via the support member 107.

  That is, the support member 107 is interposed between each of the photographing optical system 101 to the inner case 102 to the outer case 103. With this configuration, the inner surface of the outer member and the outer surface of the inner member are not in surface contact with a surface that occupies a large percentage of the surfaces, and are arranged so as to face each other with a space determined by the size of the support member 107. .

  Preferably, the outer case 103 is made of, for example, a resin having a low thermal conductivity and heat insulation so that the influence of heat from the surrounding environment on the photographing optical system 101 can be reduced. On the other hand, the inner case 102 is made of a material having higher thermal conductivity than the outer case 103, such as metal.

  If the stereo photographing apparatus 100 is mounted on a vehicle, the apparatus is disposed near the front window, for example, receives direct sunlight (SL) mainly from above, and cool air from an air conditioner (AC) from the direction of the lower dashboard. Installed to receive. If the cases 102 and 103 are not provided, the photographing optical system 101 is heated from above and cooled from below, and an extreme temperature distribution is generated at the upper and lower portions thereof. There is a possibility that thermal expansion will occur in the upper part and thermal contraction in the lower part. Due to such deformation, for example, the mirror of the photographing optical system 101 may be distorted, and the shape and optical axis may be different from those intended at the time of design. If the deformation of the constituent members of the photographic optical system 101 due to the influence of the temperature distribution as described above is large, the stereo imaging accuracy and the distance measurement accuracy based thereon are greatly reduced.

  On the other hand, when the double cases 102 and 103 are arranged around the photographing optical system 101 as shown in FIG. 2, for example, the outer resin case 103 is heated from the surrounding environment to the photographing optical system 101. It acts to reduce the effects of cooling. On the other hand, the inner case 102 is made of a material having a higher thermal conductivity than that of the outer case 103, for example, metal, and has good thermal conductivity as a whole, and the temperature around the imaging optical system 101 is made almost uniform. And has the effect of converging quickly.

  Therefore, according to the above configuration, the photographing optical system 101 is not easily affected by the ambient temperature of the stereo photographing apparatus 100 without arranging a temperature adjusting device or the like, and the entire photographing optical system 101 has a uniform temperature distribution. The temperature can be controlled so that Thereby, stereo imaging accuracy and ranging accuracy based on it can be maintained with high accuracy.

  3 and 4 show the exterior structure of the stereo photographing apparatus 100. FIG. FIG. 3 shows the upper part of the stereo photographing apparatus 100 in the form of a perspective view from the direction of the exterior member 104. In FIG. 3, two openings SP1 and SP2 of the imaging optical systems LO1 and LO2 are triangular or trapezoidal openings 1010 and 1010 formed in a lower case 1032 (see FIG. 4) constituting the lower side of the case 103. It faces the outside of the photographing device at the apex position. The openings 1010 and 1010 have a function of a hood (light-shielding member) that shields unnecessary light from entering the imaging optical systems LO1 and LO2 depending on the shape thereof. The opening angles of the triangles or trapezoids of the openings 1010 and 1010 whose apexes are the openings SP1 and SP2 are set to a sufficient value with respect to the angle of the photographing field angle of the imaging optical systems LO1 and LO2.

  FIG. 4 shows an exploded perspective view of an assembly structure of the photographic optical system 101, the cases 102 and 103, the exterior member 104, and the like of the stereo photographing apparatus 100. As shown in FIG. 4, in this structural example, the case 102 and the case 103 each have a structure that is divided into two vertically. That is, the inner case 102 includes a metal upper case 1021 and a lower case 1022, and the outer case 103 includes a resin upper case 1031 and a lower case 1032. These upper and lower cases each have, for example, a U-shaped cross section, and form a hollow container that is hermetically sealed so as to substantially wrap the inside when the upper and lower cases are assembled.

  The case 102 is held by the upper case 1021 and the lower case 1022 so as to sandwich the photographing optical system 101. The case 103 is held by the upper case 1031 and the lower case 1032 so as to sandwich the case 102 and the photographing optical system 101. At that time, a support member 107 is interposed between each of the photographing optical system 101 to the inner case 102 to the outer case 103. In FIG. 4, the support member 107 is schematically shown by an up and down arrow instead of a specific shape. Although the illustration of the horizontal direction of the support member 107 is omitted, by arranging the support member 107, as described above, each of the photographing optical system 101 to the inner case 102 to the outer case 103 is a surface. Separated so as not to touch.

  In the case of the case 103, in the example of FIG. 4, for example, the lower case 1032 has a larger outer shape than the upper case 1031 as a whole. Then, the lower case 1032 is assembled with the upper case 1031 by an inner frame portion formed of resin or the like in the same size as the upper case 1031 to form a cross-sectional structure as shown in FIG. Also, the outer shell portion outside the upper case 1031 of the lower case 1032 has a shape that can be assembled with the exterior member 104. Then, the exterior member 104 covers the upper case 1031 and the upper part of the lower case 1032 protruding from the upper case 1031, thereby completing the exterior structure of the stereo imaging device 100.

  As shown in FIG. 2, the upper exterior member 104 holds the main substrate 106 connected to the imaging element 105 incorporated in the interior, and is connected to the substrate heat generating portion with a heat conductive material. The main substrate 106 is exhausted. In the structure of FIG. 4, the image sensor 105 (105 </ b> R and 105 </ b> L in FIG. 4) is installed inside the case 102. However, the image sensor 105 (105R and 105L in FIG. 4) is configured to be installed between the case 102 and the case 103 or outside the case 103 by arranging a window or the like (not shown) through which photographing light passes. May be.

  As described above, the case 103 constituting the exterior of the stereo imaging device 100 is preferably made of a resin having a lower thermal conductivity than the case 102 in order to prevent the heat of the surrounding environment from being transmitted as much as possible. As the resin, polycarbonate resin, ABS resin, acrylic resin, MS resin, or the like can be used. A polycarbonate resin is preferable from the viewpoint that light weight and sufficient strength can be obtained. Further, the inner case 102 is preferably made of a metal having a higher thermal conductivity than the case 103 for the purpose of making the temperature unevenness formed inside as uniform as possible, such as aluminum, copper, magnesium, and the like. It is made of an alloy material using Further, as a combination of materials of the case 102 and the case 103, it is preferable that the case 103 is made of polycarbonate resin and the case 102 is made of aluminum or an aluminum alloy from the viewpoint of low cost and light weight.

  FIG. 5A, FIG. 5B, and FIG. 5C show more specific configuration examples of the support member 107 in FIG. Here, a case where the support member 107 has a separate structure from the photographing optical system 101, the case 102, the case 103, and the like is shown. However, a similar structure of the support member 107 may be integrally formed with the photographing optical system 101, the case 102, the case 103, and the like.

  The support member 1071 shown in FIG. 5A has a semi-cylindrical shape. When the support member 1071 in FIG. 5A is disposed between the photographing optical system 101 to the inner case 102 to the outer case 103, an inner member, for example, a part of the contact portion 1072 at the apex of the semicircle. In this configuration, the photographing optical system 101 and the case 102 are in line contact. The support member 1071 can be mounted on the inner surface side of the inner and outer cases 102 and 103 through a mounting surface 1073 by a technique such as adhesion.

  Further, the support member 1071 may have a hemispherical shape as shown in FIG. When the support member 1071 in FIG. 5B is arranged between the photographing optical system 101 to the inner case 102 to the outer case 103, an inner member, for example, photographing, is located at the contact portion 1072 at the apex of the hemisphere. In this configuration, the optical system 101 and the case 102 are in line contact. This support member 1071 can also be mounted on the inner surface side of the inner and outer cases 102 and 103 through the mounting surface 1073 by a technique such as adhesion.

  The support member 1071 shown in FIGS. 5A and 5B is formed using a heat insulating material having a low thermal conductivity such as a resin. Further, the support member 1071 may be made of an elastic material such as silicone rubber as a whole, similarly to the member shown as the elastic member 108 below.

  As shown in FIGS. 5A and 5B, the photographing optical system 101 to the inner case 102 to the outer case 103 are arranged with a space therebetween using a support member 1071. In this state, the support member 1071 holds the inner and outer photographing optical systems and containers by line contact or point contact, and regulates the mutual positional relationship between these members. With such a support structure, heat conduction between the cases or between the case and the photographing optical system can be suppressed, and adiabatic holding between the cases or between the case and the photographing optical system can be realized.

  Further, as shown in FIG. 5C, the elastic member 108 may be used for the entire support member 1071 or a part thereof. In this configuration, the end of the elastic member 108 becomes the mounting surface 1073 of the support member 1071. The elastic member 108 is configured to be in a compressed and deformed state in the assembled state by setting mutual dimensions of the support member 1071, the photographing optical system 101, the inner case 102, the outer case 103, and the like. With such a structure, it is possible to maintain the multiple structure of the photographing optical system 101 to the inner case 102 to the outer case 103 with an appropriate pressure. The elasticity of the elastic member 108, for example, the elasticity of the case 102 (case 103) itself may be used. That is, by appropriately selecting the material of the case 102 (case 103), by providing elasticity necessary to function as the elastic member 108, the single elastic member 108 is disposed as described above, Similar effects can be obtained.

  As described above, when the double cases 102 and 103 are made of different materials, for example, the case 102 is made of a metal material and the case 103 is made of a resin material, an imbalance of thermal expansion may occur. For example, it is conceivable that the size of one case, for example, the case 103 becomes larger depending on the temperature environment around the stereo photographing apparatus 100. In that case, when the temperature rises and thermal expansion occurs, the case 103 is deformed in a direction away from the case 102. Even when the environmental temperature changes in this way, according to the structure in which the elastic member 108 is used for the entire support member 1071 or at least a part thereof as described above, the case 102 and the case 103 are deformed by the deformation of the elastic member 108. The holding state in between can be maintained.

  Further, it is conceivable that the material and the composition of both the case 102 and the photographing optical system 101 or the lens barrel members U1 and U2 as the base material thereof are the same. In that case, the problem due to the difference in thermal expansion as described above hardly needs to be considered. Even when the environmental temperature changes, the holding state between the case 102 and the photographing optical system 101 can be maintained.

  When the support member 1071 is provided with an elastic member 108, for example, an elastic portion made of a material such as rubber, the elastic portion is affected by the vibration of the vehicle and generates unnecessary vibration such as a single vibration. there is a possibility. A member capable of damping such unwanted vibrations, for example, a vibration absorbing member made of a foam material such as various resin sponges, together with the support member 1071 and the elastic member 108, the photographing optical system 101 to the inner case 102 to the outer case 103. You may arrange | position between.

  A method for regulating the mutual positional relationship between the photographing optical system 101 and the case 102 and between the case 102 and the case 103 will be described in more detail with reference to FIGS. FIG. 6 shows a cross-sectional structure of the stereo photographing apparatus. In FIG. 6, the photographing optical system 101 is provided with a V-shaped groove 109 as a V-shaped groove as a recess, and the case 102 is provided with a support member 107 at a position facing the V-shaped groove 109. . The support member 107 has a hemispherical shape and is provided so as to be positioned substantially at the center of the V-shaped groove 109, and is in point contact with the two surfaces on the opening side of the V-shaped groove. Note that the apex portion facing the opening side of the V-shaped groove may be somewhat rounded. Any shape that allows the two surfaces and the support member to contact each other is acceptable.

FIG. 7 is a perspective view of the stereo imaging device from below, and is a diagram for explaining the arrangement of the V-shaped groove 109 in more detail. The photographing optical system 101 is provided with three V-shaped grooves 1091, 1092, and 1093 as shown in FIG. Of the three V-shaped grooves, two (1092, 1093) are arranged on a straight line, and the other one (1091) is not arranged on the same straight line. Here, the V-shaped groove 1092 and the V-shaped groove 1093 exist on a straight line, and the groove direction is also parallel, whereas the V-shaped groove 1091 includes the V-shaped groove 1092 and the V-shaped groove 1093. It is not on a straight line but is orthogonal to the two groove directions. Note that the direction of the V-shaped groove is not limited to this combination, and any V-shaped groove may not be arranged in parallel.
As the positional relationship between the three V-shaped grooves, it is preferable that the center of gravity of the photographing optical system 101 is located inside a triangle connecting the centers thereof. Further, by providing the V-shaped groove 1091 in the vicinity of the imaging element 105 having a relatively heavy weight, the center of gravity of the photographing optical system 101 is located inside the hatched triangular shape shown in FIG. As described above, the support member 107 is disposed at the position of the case 102 facing the three V-shaped grooves of the photographing optical system 101, and the hemispherical support member is in point contact with the V-shaped groove, so that the photographing optical The mutual positional relationship between the system 101 and the case 102 is regulated. By adopting such a configuration, it is possible to regulate the mutual positional relationship only by placing the photographing optical system 101 on the case 102, and it is not necessary to adjust the position in the side direction, thus simplifying assembly adjustment. can do. Further, the V-shaped grooves 1092 and 1093 can be formed by combining the chamfered portions provided in the respective lens barrel members when the photographing optical system 101 is configured by combining the two lens barrel members U1 and U2. .

In the above description, the photographing optical system 101 is provided with the V-shaped groove and the case 102 is provided with the support member. However, the photographing optical system 101 may be provided with the supporting member and the case 102 may be provided with the V-shaped groove.
Further, the method performed by the photographing optical system 101 and the case 102 can be applied to the regulation of the mutual positional relationship between the case 102 and the case 103. Specifically, three V-shaped grooves are provided on the outer surface of the case 102, and a hemispherical support member 107 is provided on the inner surface of the case 103 at a position facing the V-shaped groove on the outer surface of the case 102. The mutual positional relationship of 103 can be regulated. Further, the case 103 may be provided with a support member, and the case 102 may be provided with a V-shaped groove.

  Note that the configuration for restricting the mutual positional relationship between the photographing optical system 101 and the case 102 and between the case 102 and the case 103 is not limited to the above example. For example, it may be a concave portion other than the V-shaped groove. Further, the support member is not limited to one having a hemispherical top portion, and may be a convex portion having another shape. As long as the position can be regulated by mutual contact, the configuration is not limited to the configuration in which the concave portion and the convex portion are in contact at two points, but may be in the form of contact at more points, line contact, or surface contact.

  As described above, in the present embodiment, in an imaging apparatus including a reflective optical system that is installed in an environment where temperature change and distribution are significant, a configuration in which an imaging unit including at least the optical system is accommodated in a double container. Used. With this configuration, the influence of the temperature distribution over a large temperature range around the optical member can be mitigated, and deterioration of the optical performance of the reflective optical system due to thermal expansion / contraction can be suppressed. Thereby, a low-cost and high-accuracy imaging device can be realized without requiring a separate temperature control device. That is, according to the present embodiment, a compact and lightweight high-performance stereo imaging device that can be manufactured easily and inexpensively can be realized.

  In the above, an example in which the stereo image capturing device is an in-vehicle image capturing device has been described. However, the stereo image capturing device according to the present embodiment is a video that can be used for various purposes such as a mobile object such as a drone. The present invention can be applied to an imaging apparatus such as a camera or a digital still camera. In that case, the photographing system is not necessarily a stereo photographing system. The imaging apparatus of the present embodiment can be used by being connected to a base (for example, a body or a frame) of various moving bodies via a connection unit. The imaging apparatus having the configuration of the present embodiment can perform high-accuracy and high-quality imaging in various applications without depending on, for example, the ambient temperature environment, or more accurately based on it. Perform physical measurements.

  DESCRIPTION OF SYMBOLS 100 ... Stereo imaging device, 101 ... Imaging optical system, 102, 103 ... Case (container), 1021, 1031 ... Upper case, 1022, 1032 ... Lower case, 104 ... Exterior member, 105 ... Imaging element, 106 ... Main board | substrate, 107: support member, 108: elastic member.

Claims (17)

In an imaging apparatus having an imaging unit comprising a plurality of reflective optical elements provided on a base material and an imaging element that receives imaging light sequentially reflected by the plurality of reflective optical elements,
A first container that houses the imaging unit;
A second container for housing the first container,
An imaging apparatus in which the thermal conductivity of the first container is higher than the thermal conductivity of the second container. The imaging device according to claim 1,
An imaging apparatus in which the first container is made of a material whose main component is a metal. The imaging device according to claim 2,
An imaging apparatus in which a main component of the material of the first container is aluminum or an aluminum alloy. In the imaging device according to any one of claims 1 to 3,
An imaging apparatus in which the second container is made of a material mainly composed of a resin. In the imaging device according to claim 4,
An imaging apparatus in which the main component of the material of the second container is polycarbonate. In the imaging device according to any one of claims 1 to 5,
An imaging apparatus in which the reflective optical element is a mirror. In the imaging device according to any one of claims 1 to 6,
A first support member that is positioned between the imaging unit and the first container and regulates a mutual positional relationship between an outer surface of the imaging unit and an inner surface of the first container; and / or
A second support member that is positioned between the first container and the second container and regulates a mutual positional relationship between the outer surface of the first container and the inner surface of the second container;
An imaging device with In the imaging device according to claim 7,
An imaging apparatus in which the first support member and / or the second support member is made of a material having a lower thermal conductivity than the first container. In the imaging device according to claim 7 or 8,
The first support member regulates the mutual positional relationship between the outer surface of the imaging unit and a part of the inner surface of the first container through line contact or point contact,
The second support member is an imaging apparatus that regulates a mutual positional relationship between an outer surface of the first container and a part of an inner surface of the second container through line contact or point contact. In the imaging device according to any one of claims 7 to 9,
A recess is provided on one of the outer surface of the photographing unit and the inner surface of the first container, and the first support member is provided on the other.
An imaging apparatus in which the recess and the first support member are in contact. In the imaging device according to any one of claims 7 to 9,
A recess is provided on one of the outer surface of the first container and the inner surface of the second container, and the second support member is provided on the other;
An imaging apparatus in which the recess and the second support member are in contact with each other. In the imaging device according to claim 10 or 11,
The imaging device, wherein the recess is a V-shaped groove.   The imaging device according to any one of claims 10 to 12, further comprising a second recess and a third recess, and of the recess, the second recess, and the third recess, An imaging apparatus in which two are arranged on a straight line and the other is arranged at a position different from the straight line. In the imaging device according to any one of claims 7 to 13,
An imaging apparatus in which at least a part of the first support member and / or the second support member is made of an elastic material. The imaging device according to claim 14, wherein
An imaging apparatus in which the part is arranged in a compressed and deformed state. In the imaging device according to any one of claims 1 to 15,
The second plurality of reflection optical elements provided on the base so as to have an optical axis different from that of the plurality of reflection optical elements, and imaging light sequentially reflected by the second plurality of reflection optical elements are received. A second imaging device;
An imaging device further comprising:   A moving body comprising: the imaging device according to claim 1; and a connection unit that connects the imaging device to a base.

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