JP2013115701A - Imaging system - Google Patents

Abstract

An imaging system capable of providing an imaging device while suppressing the occurrence of a difference in appearance from surrounding structures without incurring a restriction on the field of view.
An image pickup optical system for forming a subject image and an image pickup apparatus having an image pickup device for acquiring a subject image formed by the image pickup optical system are installed in a structure (C). Imaging system 10 to be operated. A cover 12 having the same appearance color as the structure outer surface 19 of the structure and having translucency is provided. The cover 12 is between the imaging optical system 20 and the subject and covers the imaging device 11. A flat surface continuous with the outer surface 19 is formed and provided in the structure.
[Selection] Figure 5

Description

  The present invention relates to an imaging system used as an in-vehicle camera, a surveillance camera, or the like.

  2. Description of the Related Art Conventionally, there has been known an imaging apparatus having an imaging optical system having an optical element such as an imaging lens, and an imaging element for acquiring a company image formed thereby. In such an imaging apparatus, for example, it is considered that the imaging apparatus is widely applied to an imaging system such as an in-vehicle camera that supports a driver's visual recognition in a vehicle or a surveillance camera mounted on an ATM (Automated Teller Machine) (for example, , See Patent Document 1). Thus, when applied as an in-vehicle camera, from the viewpoint of ensuring design as a vehicle and protecting the imaging device, the imaging device is arranged in a recess provided on the surface of the trunk or hatch, above the license plate. Yes.

  However, in the imaging system described above, since the imaging device is installed in the recess provided in the trunk or hatch above the license plate, the field of view depends on the license plate, trunk (or hatch), and surrounding structures at the installation location. May be limited. It is desirable that such a field of view restriction is not present due to the nature of the in-vehicle camera (the same applies to a surveillance camera).

  In addition, in the imaging system described above, even if the imaging device is installed in a recess provided in the trunk or hatch at the top of the license plate, the imaging device and its installation location can be directly visually recognized. The difference in appearance will stand out. It is desirable that such an imaging device and its installation location are not visually different from surrounding structures from the viewpoint of improving the design as a vehicle.

  The present invention has been made in view of the above circumstances, and provides an imaging system capable of providing an imaging device while suppressing the occurrence of a difference in appearance from surrounding structures without incurring a restriction on the field of view. The purpose is to do.

  The imaging system according to claim 1 includes an imaging optical system that forms a subject image and an imaging device that has an imaging element for obtaining a subject image formed by the imaging optical system, installed in a structure. An imaging system comprising a cover having an appearance color of the same system as the structure outer surface of the structure and having translucency, the cover being between the imaging optical system and a subject, A flat surface that is continuous with the outer surface of the structure is formed while covering the imaging device, and is provided in the structure.

  In the imaging system according to the first aspect, the imaging device can be provided while suppressing the occurrence of a difference in appearance from the peripheral structure without incurring the limitation of the visual field.

It is explanatory drawing for demonstrating the back vision assistance mechanism 80 comprised using the imaging system 10 which concerns on this invention as a vehicle-mounted camera system. It is explanatory drawing seen from the front side for demonstrating the schematic structure of the imaging device 11 which the imaging system 10 has. FIG. 3 is an explanatory diagram viewed from the rear side for explaining a schematic configuration of the imaging apparatus 11. It is typical sectional drawing of the imaging device 11 obtained along the II line | wire of FIG. FIG. 2 is an explanatory diagram showing a state where an imaging system 10 is provided in a vehicle C. It is explanatory drawing which shows a mode that the imaging system 10 was provided in the vehicle C, the cover 12 and the installation space 18 are shown with the cross section obtained by the II-II line shown in FIG. 5, and others are side views for easy understanding. Is shown. 2 is a block diagram illustrating an outline of a system configuration of an electronic circuit 40 of the imaging device 11 of the imaging system 10. FIG. It is a graph which shows the output signal output from the image pick-up element 31 by which the amplification amount (gain) of the AGC circuit 43 was made basic setting for every light receiving element part 31b corresponding to RGB (RGB pixel data), and a vertical axis | shaft. The intensity ratio of the output signal with the maximum intensity being 1 is shown, and the horizontal axis shows the wavelength (nm). It is a graph which shows the transmission characteristic of the cover 12, and the vertical axis | shaft has shown the ratio (transmittance of the cover 12) of the transmitted light (electromagnetic wave) intensity | strength which sets the maximum to 1, and the horizontal axis has shown the wavelength (nm). The graph which shows the output signal output from the image pick-up element 31 with respect to the to-be-photographed image obtained through the cover 12 at the time of making a white object into a subject under natural light for every light receiving element part 31b corresponding to RGB (RGB pixel data) The vertical axis indicates the ratio of the intensity of the output signal with the maximum output being 1, and the horizontal axis indicates the wavelength (nm). It is a graph which shows the setting correction value of the amplification amount (gain) in the AGC circuit 43, the vertical axis shows the setting correction value, and the horizontal axis shows the wavelength (nm). The intensity of the output signal as a subject image acquired through the cover 12 by using a white object under natural light as a subject from the image sensor 31 in which the AGC circuit 43 is set to an amplification amount (gain) corresponding to the transmission characteristic of the cover 12 Is a graph showing R, G, and B, the vertical axis indicates the ratio of the intensity of the output signal with the maximum intensity being 1, and the horizontal axis indicates the wavelength (nm). It is a graph which shows the setting correction value of the other example of the amplification amount (gain) in the AGC circuit 43, the vertical axis shows the setting correction value, and the horizontal axis shows the wavelength (nm). FIG. 9 is a block diagram similar to FIG. 7 illustrating an overview of the system configuration of the electronic circuit 40B of the imaging device 11B of the imaging system 10B according to the second embodiment. It is a block diagram which shows the outline | summary of the system configuration | structure of the imaging system 10C of Example 3. FIG. It is explanatory drawing which shows the outline | summary of a structure of imaging system 10D. It is a graph which shows the transmission characteristic of the band pass filter 61, the vertical axis | shaft shows ratio (transmittance of the band pass filter 61) of the transmitted light (electromagnetic wave) intensity | strength which sets the maximum to 1, and a horizontal axis shows a wavelength (nm). Show.

  Embodiments of an imaging system according to the present invention will be described below with reference to the drawings.

  First, the concept of the imaging system according to the first embodiment of the present invention will be described. FIG. 1 is an explanatory diagram for explaining a rear view assisting mechanism 80 configured using the imaging system 10 according to the present invention as an in-vehicle camera system. FIG. 2 is an explanatory diagram viewed from the front side for explaining a schematic configuration of the imaging device 11 included in the imaging system 10, and FIG. 3 is a rear side for explaining the schematic configuration of the imaging device 11. It is explanatory drawing seen from. FIG. 4 is a schematic cross-sectional view of the imaging device 11 obtained along the line II in FIG.

  As shown in FIG. 1, the imaging system 10 basically includes an imaging device 11 and a light-transmitting cover 12 and is provided in a structure (vehicle C in the illustrated example) as an installation target. The imaging device 11 acquires an image in a predetermined range on the photographing optical axis OA. The cover 12 is provided on the surface of the installation location in the structure (the structure outer surface 19 (see FIG. 5 and the like described later)) on the imaging optical axis OA of the imaging device 11. Detailed configurations of the imaging device 11 and the cover 12 will be described in detail later.

  In the first embodiment, the imaging system 10 configures an in-vehicle camera system in the vehicle C with the structure to be installed as the vehicle C. The imaging system 10 constitutes a rearward visual assistance mechanism 80 for assisting the visual recognition of the rear of the vehicle by an occupant, particularly a driver. In the rear view assisting mechanism 80, the imaging device 11 of the imaging system 10 is provided at the rear end position of the vehicle C toward the rear obliquely lower side of the vehicle C, and the rear oblique lower side region of the vehicle C is defined. A wide-angle range centering on the image is taken as a subject of photographing.

  The rear viewing support mechanism 80 includes a control device 81 connected to the imaging system 10 and a monitor 82 connected to the imaging system 10 via the control device 81. In the rear view assisting mechanism 80, the control device 81 displays an image behind the vehicle on the monitor 82 based on the electrical signal (image data) output from the imaging system 10. Although not shown, the control device 81 is switched when the transmission gear (not shown) of the vehicle C is switched to the reverse (reverse) or when a signal for displaying an image of the rear of the vehicle is input. An image behind the vehicle acquired by the imaging system 10 is displayed on the monitor 82. The monitor 82 is a display unit provided at a position in the passenger compartment of the vehicle C that facilitates visual recognition by an occupant, particularly a driver. Although not shown, the monitor 82 may also serve as a display unit of the navigation system. For this reason, the occupant, particularly the driver, can easily recognize the rear of the vehicle C from the image of the monitor 82 when the rear confirmation of the vehicle C is required. Can help.

  Next, a schematic configuration of the imaging device 11 of the imaging system 10 according to the present invention will be described with reference to FIGS. The imaging device 11 is generally configured by housing an imaging optical system 20 and an electronic circuit unit 30 inside a housing 13. In the following, when viewed in the direction along the imaging optical axis OA of the imaging optical system 20, the side from the imaging device 11 toward the subject (the direction indicated by the arrow OA) is referred to as the front, and the opposite side is referred to as the rear. Further, a direction passing through the photographing optical axis OA and orthogonal to the photographing optical axis OA (radiation direction from the photographing optical axis OA) is referred to as a radial direction.

  In the first embodiment, the housing 13 includes a front case 14 that supports the imaging optical system 20 and a rear case 15 that houses the electronic circuit unit 30. The front case 14 constitutes a front portion (front housing portion) of the housing 13, and photographing of an objective lens (lens 21a described later in this example) of the imaging optical system 20 is performed on an end surface on the front side (one end side). The circumference | surroundings seen in the direction (radial direction) orthogonal to optical axis OA are enclosed.

  As shown in FIG. 4, the front case 14 has a holding hole 14 a for accommodating the imaging optical system 20, and a photographing optical axis at a location where the diameter is widened at the front portion (a large inner diameter portion 14 d described later). A sealing annular groove 14b surrounding the OA and a mounting groove 14c surrounding the holding hole 14a on the front end surface are provided. The holding hole 14a is a stepped cylindrical through-hole having the photographing optical axis OA as an axis, and can hold an optical element group 21 (described later) of the imaging optical system 20 at an appropriate position and posture. Yes. The holding hole 14a has a large inner diameter portion 14d capable of receiving a lens 21a as an optical element group 21 described later from the front side (subject side), and an inner diameter that is adjacent to the large inner diameter portion 14d and smaller than the large inner diameter portion 14d. A portion 14e, and a small inner diameter portion 14f adjacent to the portion 14e and having a smaller inner diameter than the middle inner diameter portion 14e. In the holding hole 14a, an orthogonal surface 14g orthogonal to the direction of the photographing optical axis OA is formed due to the difference in diameter between the large inner diameter portion 14d and the middle inner diameter portion 14e.

  The orthogonal face 14g is provided with the sealing annular groove 14b described above. This annular groove 14b for sealing is a recess for arranging a sealing member 24 described later, and has an annular shape surrounding the inner diameter part 14e. The mounting groove 14c surrounding the holding hole 14a (large inner diameter portion 14d) is provided with a screw thread on the inner peripheral surface, and can be engaged with the screw thread while receiving a rear end portion 23b of a retaining member 23 described later. Has been. Further, in the holding hole 14a, an optical element group 21 (its lens 21f) to be held as will be described later on the rear side (on the imaging element 31 side described later) of the small inner diameter portion 14f, that is, the rear end (other end) of the front case 14. An inner edge protrusion 14h is provided to prevent the dropout of the inner edge. The inner edge protrusion 14h has an annular shape that protrudes inward in the radial direction at the rear end of the small inner diameter portion 14f, and forms a hole having a diameter smaller than the inner diameter of the small inner diameter portion 14f. ing.

  In addition, the front case 14 has four support wall portions 14i (only three are shown in FIG. 4) and a fixing annular groove surrounding each support wall portion 14i on the rear end surface facing the rear case 15. 14j. The four support walls 14i are paired on a line orthogonal to each other in the radial direction so as to surround the imaging optical axis OA outside the inner edge protrusion 14h as viewed in the radial direction. It will be a place to support. The fixing annular groove 14j is an annular groove provided on the rear end surface of the front case 14 so as to surround the four support wall portions 14i, and is a base end of a shield case 34 (its main body sheet metal portion 35) described later. The part 35a can be received.

  The rear case 15 attached to the rear end of the front case 14 constitutes a rear portion (rear housing portion) of the housing 13. The rear case 15 has an open box shape at one end, and has a back wall portion 15a on the rear end side, and a cylindrical peripheral wall portion 15b protruding from the rear wall portion 15a toward the open end side. The rear case 15 has a size (depth dimension) in which the electronic circuit unit 30 can be inserted from the open end and can accommodate the electronic circuit unit 30 attached to the front case 14. ing. For this reason, in the rear case 15, the direction of the photographing optical axis OA is the insertion direction of the electronic circuit unit 30. As shown in FIGS. 3 and 4, the rear case 15 has a housing 13, that is, an imaging device 11 for attaching the imaging device 11 to a desired place on the outer wall surface of the rear wall portion 15 a (rear end surface of the rear case 15). Two mounting projections 15c are provided. Both the mounting projections 15c are bosses provided with screw holes (see FIG. 3).

  Further, the rear case 15 is supplied with electric power to the electronic circuit unit 30 (an electronic circuit 40 described later (see FIG. 7)) or transmits image data acquired by an image sensor 31 described later of the electronic circuit unit 30. A connection cord 16 is provided. The connection cord 16 can be connected to the electronic circuit unit 30 in a state of having sealing performance with the outside with respect to the rear case 15. Therefore, the connection cord 16 functions as a connection unit that connects the electronic circuit unit 30 to the outside of the housing 13. In the first embodiment, the connecting cord 16 is provided with a connector portion 16a at one end on the rear case 15 side, and this connector portion 16a interposes an O-ring 16b as a sealing member and is not shown in the figure. The member is fixed to the rear end surface of the rear case 15. In addition, as a configuration having sealing performance, a connection hole (not shown) is provided in the rear case 15 and the connection cord 16 is inserted therein and the periphery is filled with a waterproof adhesive, or the connection cord 16 (The covering member) may be formed integrally with the rear case 15.

  The rear case 15 having such a configuration is such that the front end surface is attached to the rear end surface of the front case 14 with a sealing member 17 formed of an O-ring or flat packing made of an elastic material interposed therebetween. By being coupled with a stopper or the like, the housing 13 has a waterproof function and a dust-proof function (hereinafter referred to as sealing performance) at the joint location, and serves as a housing member that houses the imaging optical system 20 and the electronic circuit unit 30. Form.

  The imaging optical system 20 accommodated in the housing 13 forms an image at an arbitrary position for image acquisition, and has at least one or more optical elements as shown in FIG. 11 (imaging optical system 20) is appropriately configured according to the optical performance required. In the first embodiment, the imaging optical system 20 is configured such that an optical element group 21 including a plurality of optical elements is accommodated in a holding hole 14 a of the front case 14 together with a spacing ring 22.

  When the optical element group 21 is assembled in the holding hole 14a, the interval ring 22 defines the distance in the direction of the photographing optical axis OA between the opposing surfaces of each optical element of the optical element group 21 to a predetermined value. To do. The spacing ring 22 has a stepped cylindrical shape with the photographing optical axis OA as an axis, and has a size that can be inserted into the holding hole 14a. Further, the interval ring 22 has an inner diameter dimension that allows accommodation of a predetermined optical element in the optical element group 21. In the first embodiment, the spacing ring 22 has a size that can be inserted into the medium inner diameter portion 14e in the holding hole 14a and cannot be inserted into the small inner diameter portion 14f, and will be described later as a predetermined optical element. The inner diameter of the lens 21b and the lens 21c can be accommodated.

  In the interval ring 22, an inner edge protrusion 22 a and a diaphragm 22 b are provided on the rear side (image sensor 31 side described later), that is, on the rear end side (other end side). The inner edge protrusion 22a prevents a predetermined optical element (a lens 21c described later in the first embodiment) from dropping out of the optical element group 21 inserted in the interval ring 22 (inward thereof). The diaphragm 22b defines an effective diameter (effective light beam diameter) in the optical element group 21 (imaging optical system 20). The spacing ring 22 is accommodated in the holding hole 14 a of the front case 14 together with the optical element group 21.

  In the first embodiment, the optical element group 21 includes a lens 21a, a lens 21b, a lens 21c, a lens 21d, a lens 21e, and a lens 21f in this order from the subject (object) side. In the optical element group 21, the lens 21d, the lens 21e, and the lens 21f are accommodated in the small inner diameter portion 14f of the holding hole 14a, and the lens 21b and the lens 21c are accommodated in the spacing ring 22 in the inner inner diameter portion 14e of the holding hole 14a. The lens 21a is accommodated in the large inner diameter portion 14d of the holding hole 14a. For this reason, in the optical element group 21, a stop 22b of the spacing ring 22 is disposed between the lens 21c and the lens 21d. The interval ring 22 holds the intervals in the photographing optical axis OA direction between the opposing surfaces of the lens 21a, the lens 21b, the lens 21c, and the lens 21d at a predetermined value. In this optical element group 21, the lens 21a is an objective lens located closest to the subject (object). The holding hole 14 a (front case 14) functions as a lens barrel that holds the optical element group 21 as the imaging optical system 20. In this specification, the optical axis in the imaging optical system 20, that is, the rotational symmetry axis of each of the lenses 21a to 21f (including the diaphragm 22b) that is the central axis position of the optical element group 21 (holding hole 14a), The imaging optical system 20, that is, the imaging optical axis OA of the imaging device 11 is assumed.

  The optical element group 21 inserted into the holding hole 14a is prevented from dropping from the opening on the large inner diameter portion 14d side by the retaining member 23. The retaining member 23 has a cylindrical shape with a size that can surround the outer peripheral surface of the lens 21a serving as an objective lens, and the front end portion 23a (the subject-side end portion) is the surface (front surface) of the lens 21a. It is set as the diameter dimension which can contact the peripheral part (outside position of an effective diameter) from the outside (front side). Further, the retaining member 23 is provided with a screw thread at the rear end portion 23b that can be inserted into the mounting groove 14c of the front case 14, and can be engaged with the screw thread of the mounting groove 14c. Yes. In the state where the optical element group 21 is appropriately inserted into the holding hole 14a together with the spacing ring 22 and the annular sealing member 24 is disposed in the sealing annular groove 14b, the retaining member 23 is formed on the rear end 23b. When the screw thread is engaged with the screw thread of the mounting groove 14c, the lens 21a is attached to the front case 14 so as to cover the lens 21a while pressing the lens 21a toward the back surface side (the rear case 15 side (image surface side)). It is done. The sealing member 24 provided in the sealing annular groove 14b is formed of an elastic material, and is an O-ring in the first embodiment.

  Thereby, the sealing member 24 arrange | positioned between the back surface of the lens 21a and the annular groove 14b for sealing is compressed appropriately. For this reason, in the imaging optical system 20, the sealing member 24 that is appropriately compressed prevents water and dust from entering the holding hole 14a from the periphery of the lens 21a, and has sufficient sealing performance. ing. As described above, in the imaging optical system 20, the optical element group 21 (the lens 21a serving as the objective lens) is sealed in a sealed manner by the front case 14 (holding hole 14a) and has a desired optical performance. At this time, the spacing ring 22 is formed in the holding hole 14a by the lens 21a fixed by the retaining member 23 and the holding hole 14a of the front case 14 (a step between the inner diameter portion 14e and the small inner diameter portion 14f). It is fixed to. An electronic circuit unit 30 (an imaging element 31 described later) is disposed at the imaging position of the optical element group 21 of the imaging optical system 20.

  The electronic circuit unit 30 includes an image sensor 31, a first substrate 32, a second substrate 33, and a shield case 34. The imaging device 31 is a solid-state imaging device configured using a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal Oxide Semiconductor), or the like, and passes through the imaging optical system 20 (the optical device group 21) on the light receiving surface 31a. Are converted into electrical signals (pixel data) from the respective light receiving element portions 31b (see FIG. 7) and output. The imaging element 31 is set to have sensitivity to light in the visible region and the infrared region (wavelength thereof). In addition, although not shown, the image pickup device 31 is provided with a Bayer array color filter corresponding to the plurality of light receiving element portions 31b, and the electrical signal (each pixel data) to be output is the Bayer array RGB pixel data. Become. The electrical signal output from the image sensor 31 is generated and output as digital image data corresponding to the subject image by an electronic circuit 40 described later. In order to efficiently exhibit the optical performance set as the imaging optical system 20 (optical element group 21), the imaging element 31 has a substantial effect on the subject image formed by the imaging optical system 20 (optical element group 21). A position with respect to the imaging optical system 20 (holding hole 14a for holding it) is set and provided on the first substrate 32 so as to exist at an appropriate position on the light receiving surface 31a forming the light receiving region.

  The first substrate 32 has a rectangular plate shape as a whole although not clearly shown, and the image pickup device 31 is mounted on the front surface on the subject side, that is, the image pickup optical system 20 side, and a capacitor, a resistor, or the like is provided on the rear surface. An electronic component 32a is mounted. The first substrate 32 is fixed to the rear end surfaces of the four support wall portions 14i of the front case 14 through a fixing member (not shown) substantially orthogonal to the photographing optical axis OA. A connector member 32 b is provided on the rear surface of the first substrate 32. A second substrate 33 is provided on the rear side of the first substrate 32 (the rear end side of the rear case 15).

  The second substrate 33 has a rectangular plate shape as a whole although not clearly shown, and an electronic component 33a such as a capacitor and a resistor and a connector member 33b are mounted on the subject side, that is, the front surface on the imaging optical system 20 side. An electronic component 33c such as a capacitor or a resistor is mounted on the rear surface. The second substrate 33 is provided in parallel with the first substrate 32 on the rear side of the first substrate 32 (the rear end side of the rear case 15), and the connector member 33b is connected to the connector member 32b. Thus, the first substrate 32 is electrically connected. In the second substrate 33, a connector member 33d is mounted on the rear surface. The connector member 33d enables electrical connection between the connection cord 16 fixed to the rear end surface of the rear case 15 and the second substrate 33 via the connector portion 16a.

  In the first substrate 32 and the second substrate 33, a predetermined electronic circuit 40 (see FIG. 7) is constituted by the electronic components 32a, 33a and 33c provided respectively. The electronic circuit 40 controls the operation of the image sensor 31, generates digital image data corresponding to the subject image based on the electrical signal output from the image sensor 31, and converts the digital image data into a predetermined signal. And output to the connection cord 16. The configuration of the electronic circuit 40 will be described later. For this reason, the electronic circuit unit 30 can output the image acquired by the image sensor 31 as a video signal. The reason why the two-layer substrates 32 and 33 are provided in this way is to reduce the size of the imaging device 11 while satisfying the required performance. Therefore, the substrate for the configuration of the electronic circuit 40 may have a structure of only one layer or may be provided in multiple layers, taking into account the number, size, shape, etc. of each electronic component to be mounted. May be set as appropriate. A shield case 34 is provided so as to surround the two substrates 32 and 33 that are electrically connected in parallel in the direction of the photographing optical axis OA.

  The shield case 34 constitutes an electromagnetic shield for preventing electromagnetic waves from being emitted from the electronic circuit 40 (see FIG. 7) to the surroundings and the influence of the electromagnetic waves on the electronic circuit 40 from the surroundings. The shield case 34 is formed of a conductive material and is electrically connected to a reference potential or ground level in the electronic circuit 40. The shield case 34 is made of a metal material, and is made of aluminum in the first embodiment. The shield case 34 includes a main body sheet metal part 35 and a rear sheet metal part 36.

  The main body sheet metal portion 35 is formed by bending a thin plate-like member made of aluminum and has a cylindrical shape whose cross section viewed in a direction orthogonal to the photographing optical axis OA is substantially rectangular although not clearly illustrated. ing. The main body sheet metal portion 35 has a shape and size that can be fitted into the peripheral wall portion 15b of the rear case 15 while allowing the electronic circuit unit 30 to be surrounded in a direction surrounding the photographing optical axis OA. ing. For this reason, the main body sheet metal part 35 forms an outer peripheral surface parallel to the photographing optical axis OA in the electronic circuit unit 30. The main body sheet metal portion 35 is provided with pressing pieces 35b (only two are shown in FIG. 4) on each of the four wall portions constituting the base end portion 35a serving as an attachment location to the front case 14. . When each of the pressing pieces 35b is inserted into the fixing annular groove 14j while the base end portion 35a surrounds the four support wall portions 14i (only three are shown in FIG. 4) of the front case 14, the fixing ring 35b One inner wall surface of the groove 14j is pressed (see FIG. 4). Thereby, the main body sheet metal part 35 is attached to the front case 14.

  Although the main body sheet metal part 35 is not clearly shown, the main body sheet metal part 35 has a support part that receives a protrusion part that protrudes in the radial direction on the second substrate 33, and can be fixed to the second substrate 33 accommodated inside. It is possible. Although not shown, the main body sheet metal part 35 is electrically connected to a circuit reference potential in a predetermined electronic circuit 40 (see FIG. 7) formed by each electronic component of the second substrate 33 accommodated inside. . In the first embodiment, the main body sheet metal part 35 is electrically connected to a connection line (not shown) to the circuit reference potential of the electronic circuit 40 provided on the second substrate 33.

  The rear sheet metal portion 36 is formed of a thin plate member made of aluminum, and is formed into a plate shape having a substantially rectangular shape when viewed in a direction orthogonal to the photographing optical axis OA although not shown. The rear sheet metal portion 36 is fixed to the rear case 15 in parallel with the back wall portion 15a (the inner wall surface). The rear sheet metal part 36 is provided with a plurality of connection protrusions 36a (only two are shown in FIG. 4) and a receiving hole part 36b. Each connection protrusion 36a constitutes a contact portion between the main body sheet metal part 35 and the rear sheet metal part 36, and a part of the rear sheet metal part 36 is formed to protrude to the front side (second substrate 33 side). ing. Each connection protrusion 36a is pressed against the rear end portion 35c of the main body sheet metal portion 35 in the assembled state as will be described later. The receiving hole portion 36b allows the connector member 33d mounted on the second substrate 33 to pass therethrough.

  Thus, in the imaging device 11, the imaging optical system 20 and the electronic circuit unit 30 are accommodated and formed in the housing 13 serving as a housing member. Inside the casing 13, the electronic circuit unit 30 is surrounded by the main body sheet metal part 35 and the rear sheet metal part 36 whose rear end part 35 c is pressed against each connection projection part 36 a while surrounding the electronic circuit unit 30. An electromagnetic shield electrically connected to the circuit reference potential in (see FIG. 7) is formed. As described above, the imaging device 11 is provided at the rear portion of the vehicle C together with the cover 12 to constitute the imaging system 10.

  As shown in FIGS. 5 and 6, the cover 12 is provided so as to cover an installation space 18 for installing the imaging device 11 provided in the vehicle C as a structure on which the imaging system 10 is installed. The installation space 18 has an opening at the rear end surface (structure outer surface 19) of the vehicle C, and has a size that can accommodate the imaging device 11. The installation space 18 is set to have a size and shape, particularly an opening size on the structure outer surface 19 so as not to limit the field of view of the imaging device 11 (its imaging optical system 20). Limiting the field of view means that a part of the installation space 18 and the outer surface 19 of the structure enters the field of view, so that the field of view that can be substantially acquired is narrowed. This means that the entire range of the side area cannot be acquired. In the installation space 18, the imaging device 11 is attached and accommodated by a screw member (not shown) engaged with both attachment protrusions 15 c (see FIG. 3 and the like) of the rear case 15. As described above, the imaging device 11 has an angle and a position set so that a wide-angle range centered on the image from the installation space 18 and the diagonally lower area of the rear side of the vehicle C is an object to be imaged (FIG. 1). reference). The peripheral position surrounding the installation space 18 (the opening thereof), that is, the structure outer surface 19 (the surface at the rear end position of the vehicle C) is green in Example 1 when viewed under natural light (white light).

  The cover 12 is provided in the vehicle C by closing the opening of the installation space 18 and forming a plane continuous with the structure outer surface 19 at the cover surface 12a (see FIG. 6). For this reason, the imaging device 11 accommodated in the installation space 18 is covered with a cover 12 that forms the same plane as the structural outer surface 19. The cover 12 has the same color as that of the outer surface 19 of the structure when viewed from the outside under natural light (white light) (appearance color). The system here refers to the aspect of color (color) from the viewpoint of reducing the difference in hue with the structure outer surface 19 of the structure as an installation target when viewed from the outside under natural light (white light). The so-called hues are roughly divided and set. In the first embodiment, this system is divided into five systems of purple, blue, green, yellow, and red, excluding white and black. Each of these systems is represented by wavelength bands in light (electromagnetic waves), purple (380-450 nm), blue (450-495 nm), green (495-570 nm), yellow (570-620 nm), red (620-750 nm). It is said. For this reason, the cover 12 (imaging system 10) can reduce the difference in hue with respect to the structure outer surface 19 of the structure excluding white and black.

  The relationship between color and wavelength defining this system means a typical color-wavelength relationship indicating the wavelength of monochromatic light in a narrow range that can be measured by a measuring instrument or the like. Here, if the above system is defined in the chromaticity diagram (color is expressed by how the human eye perceives) defined by the International Commission on Illumination (CIE), the wavelength spectrum is the result of the combination of multiple wavelengths. Even if they are different, they may be felt in the same color, and the combination becomes infinite, so it is difficult to handle with the expression of color as a human feeling. For this reason, in Example 1, the color is captured as a wavelength, and the system is defined as described above. This system does not place emphasis on exact numerical values (wavelengths) at the boundaries of each category, but only needs to be classified to the extent that humans can feel this color, and is limited to the categories represented by the above wavelength bands. Is not to be done.

  This cover 12 has translucency that allows transmission of light (electromagnetic waves) in the entire infrared region and visible region, and the color of the transmitted light that has transmitted natural light (white light) (transmitted light on the white surface). It is made of a material that makes the color of the irradiated portion) substantially equal to the appearance color (at least the above-mentioned system is the same). That is, the cover 12 feels the same color (the above-described system) when viewed from the outside and when viewed through natural light (white light). This can be considered as follows. In the cover 12 (its material), in the appearance color as an object, the influence of the light reflected on the surface and the light emitted from the surface to the outside through the inside by having transparency is large. it is conceivable that. Here, since various light is reflected on the surface, the color of the appearance is not determined in the former. On the other hand, the latter is incident from the front surface of the cover 12 (its material) inward, then reflected from the back surface without exiting from the back surface and exiting from the front surface to the outside. Therefore, it has the same characteristics as transmitted light. For this reason, in the cover 12 (the material thereof), it is considered that the apparent color as an object appears as the color of the light transmitted through the cover 12. Further, the cover 12 (the material thereof) has an action of absorbing light in a specific wavelength band so as to form a set appearance color and allowing transmission of light (electromagnetic waves) in the entire infrared region and visible region. It is considered a thing. In other words, in the cover 12 (its material), if the wavelength band of light (electromagnetic wave) that forms the set appearance color is the appearance wavelength band, the cover 12 absorbs light in the remaining wavelength band other than the appearance wavelength band, and the remaining wavelength. The complementary color for the band is the appearance color (appearance wavelength band).

  In Example 1, the cover 12 is formed by adding a pigment having an appearance color to a transparent material such as a glass material, polycarbonate, or acrylic. In the first embodiment, the outer color of the outer surface 19 of the cover 12 is green as described above.

In this cover 12, the cover surface 12a continuous to the structure outer surface 19 is provided with antifouling measures that make it difficult for water, dust, and the like to adhere. In Example 1, the cover surface 12a is made of silica (SiO ₂ ). An antifouling film is provided (coating). Since this antifouling film can be made extremely thin, it hardly affects the optical path of light incident on the imaging device 11 through the cover 12.

  In the imaging system 10, the light transmitted through the cover 12 is acquired by the imaging device 11. Therefore, in the imaging system 10, the electronic circuit 40 (see FIG. 7) in the imaging device 11 is configured as follows. A schematic configuration of the electronic circuit 40 is shown in FIG. FIG. 7 is an explanatory diagram for explaining the configuration of the electronic circuit 40 formed in the electronic circuit unit 30 of the imaging system 10 (imaging device 11).

  As shown in FIG. 7, the electronic circuit 40 includes a signal processing circuit 41 and a control unit 42 in addition to the image sensor 31. In the electronic circuit 40, the control unit 42 gives necessary control signals to the image pickup device 31 and the signal processing circuit 41, thereby controlling their operations in a pipeline manner. In addition, although not shown, the control unit 42 is a power supply circuit that supplies power supplied from the connection cord 16 to drive the imaging device 31 and the signal processing circuit 41 (each electronic component 32a, 33a, and 33c). Also works.

  The image sensor 31 is provided with an AGC circuit 43. The AGC circuit 43 is an analog gain control unit, and amplifies an analog image signal (Bayer array RGB pixel data) output from each light receiving element unit 31b corresponding to RGB in the image sensor 31 to a predetermined value. Output to the signal processing circuit 41 (A / D converter 44 described later). That is, in the first embodiment, the image sensor 31 has a gain adjustment function for adjusting the amplification amount (gain) of the output signal (RGB pixel data) from each light receiving element unit 31b corresponding to RGB. The setting of the amplification amount (gain) in the AGC circuit 43 will be described later.

  The signal processing circuit 41 includes an A / D converter 44, an image generation unit 45, and an output conversion unit 46. The A / D converter 44 converts the Bayer array RGB pixel data as an analog signal amplified by the AGC circuit 43 and output from the image sensor 31 into a digital signal, and outputs the digital signal to the image generation unit 45.

  When the RGB pixel data of the Bayer array converted into a digital signal is input, the image generation unit 45 generates color component pixel data at all coordinate positions by linear interpolation based on the RGB pixel data independently for each of the RGB colors. The generated pixel data is appropriately corrected (aberration correction, MTF correction, distortion aberration correction, gamma correction, etc.), and image data is generated based on the pixel data. The image generation unit 45 outputs the generated image data to the output conversion unit 46.

  The output conversion unit 46 converts the input image data into a predetermined signal. Examples of the predetermined signal include a video signal corresponding to VGA (Video Graphics Array), and a video signal corresponding to NTSC (National Television System Committee) and PAL (Phase Alternating Line). The output conversion unit 46, that is, the signal processing circuit 41 outputs the image data converted into a predetermined signal to the connection cord 16 (see FIG. 4).

  Next, setting of the amplification amount (gain) in the AGC circuit 43 of the image sensor 31 will be described with reference to FIGS. FIG. 8 is a graph showing an output signal output from the image sensor 31 in which the amplification amount (gain) of the AGC circuit 43 is basically set for each light receiving element unit 31b corresponding to RGB (RGB pixel data). The vertical axis indicates the ratio of the intensity of the output signal with the maximum intensity being 1, and the horizontal axis indicates the wavelength (nm). FIG. 9 is a graph showing the transmission characteristics of the cover 12, where the vertical axis indicates the ratio of transmitted light (electromagnetic wave) intensity with the maximum being 1 (transmittance of the cover 12), and the horizontal axis indicates the wavelength (nm). Show. FIG. 10 shows an output signal output from the image sensor 31 for a subject image acquired through the cover 12 when a white object is used as a subject under natural light, divided into light receiving element units 31b corresponding to RGB (RGB pixels). Data), the vertical axis indicates the ratio of the intensity of the output signal with the maximum output being 1, and the horizontal axis indicates the wavelength (nm). FIG. 11 is a graph showing the setting correction value of the amplification amount (gain) in the AGC circuit 43, where the vertical axis shows the setting correction value and the horizontal axis shows the wavelength (nm). FIG. 12 shows a subject image acquired through the cover 12 by using a white object as a subject under natural light from the image sensor 31 in which the AGC circuit 43 is set to an amplification amount (gain) corresponding to the transmission characteristic of the cover 12. It is a graph which shows the intensity | strength of an output signal separately for RGB, the vertical axis | shaft shows the ratio of the intensity | strength of the output signal which makes the maximum intensity | strength 1, and the horizontal axis shows the wavelength (nm).

  As described above, the image pickup element 31 (each light receiving element portion 31b) has sensitivity to light in the visible region and the infrared region (wavelength thereof), and is configured by being provided with a Bayer color filter. On the other hand, the AGC circuit 43 basically has an amplification amount for each light receiving element portion 31b corresponding to RGB so that the subject image becomes white when a white object is used as a subject under natural light (white light). (Gain) is set. This is the basic setting. This basic setting is set in consideration of the characteristics of the imaging apparatus 11 (mainly the transmission characteristics of the imaging optical system 20). For this reason, in the imaging device 11, in the output signal output from the imaging device 31 for a white object under natural light (white light), as shown in FIG. 8, for each light receiving element unit 31b corresponding to RGB. The intensities of the output signals (RGB pixel data) are equal to each other.

  Here, in the imaging system 10, since the light transmitted through the cover 12 is acquired by the imaging device 11, the acquired subject image (image based thereon) is affected by the transmission characteristics of the cover 12. Here, in the cover 12, when there is no bias in transmission characteristics at least in the visible region, the amplification amount (gain) in the AGC circuit 43 (imaging device 31) is set to the basic setting described above (see FIG. 8). Further, when the cover 12 is biased in transmission characteristics at least in the visible region, an amplification amount (gain) in the AGC circuit 43 (imaging device 31) is set according to the bias. The bias in the transmission characteristics referred to here means that a difference is caused between the subject and the output image (subject image) as seen by human eyes. In the first embodiment, this difference is performed using a white object as a subject under natural light (or white light).

  Here, in the first embodiment, as described above, the cover 12 has a green appearance color (appearance wavelength band) which is the same system as the structure outer surface 19 (see FIG. 5 and the like) and is transmitted. The color of the transmitted light is assumed to be equal to the appearance color. For this reason, in the cover 12, the transmission characteristics are biased, and the transmission characteristics shown in the graph of FIG. That is, in the cover 12, the transmittance (appearance transmittance) in the outer wavelength band (particularly the wavelength band from 560 nm to 580 nm) is local to the transmittance (residual transmittance) in the remaining wavelength band which is another wavelength band. When the natural light (white light) is transmitted, it becomes a greenish transmitted light and forms a green shadow. As described above, the cover 12 has a transmission characteristic in which the residual transmittance in the remaining wavelength band other than the appearance transmittance in the outer wavelength band that forms the outer color is a constant value.

  For this reason, in the imaging system 10, when the AGC circuit 43 (imaging device 31) is set to the above-described basic amplification amount (gain) (see FIG. 8), imaging is performed on a white object under natural light (white light). As shown in FIG. 10, the output signal from the element 31 is an output signal (G pixel data) from the light receiving element portion 31b corresponding to G in the output signal (RGB pixel data) for each light receiving element portion 31b corresponding to RGB. ) Is larger (substantially twice) than the intensity of the output signal (RB pixel data) from the light receiving element portion 31b.

  Therefore, in the AGC circuit 43 (imaging device 31) of the first embodiment, in order to set the amplification amount (gain) according to the bias in the transmission characteristics of the cover 12, the basic setting amplification amount (gain) is 11 is set as an amplification amount (gain). This setting correction value is a characteristic line that indicates the reciprocal of the transmission characteristic of the cover 12 with the maximum value being 1. In other words, the setting correction value relatively reduces the amplification amount (gain) in the high transmittance region in the bias of the transmission characteristics of the cover 12. As described above, in the imaging system 10, since the AGC circuit 43 of the imaging device 31 has an amplification amount (gain) obtained by multiplying the basic setting by the above-described setting correction value (see FIG. 11), it is under natural light (white light). For a white object, as shown in FIG. 12, the intensity of the output signal (RGB pixel data) for each light receiving element portion 31b corresponding to RGB can be made equal to each other. That is, the imaging system 10 generates a white image (image data) for a white object under natural light (white light). For this reason, in the imaging system 10 of the first embodiment, the AGC circuit 43 in the imaging device 31 outputs an output signal (from the light receiving element portion 31b corresponding to G, which is a component formed by light in the appearance wavelength band in the subject image ( G pixel data) and a correction mechanism that cancels the difference in intensity between the light receiving element portion 31b corresponding to RB that is a component formed by light in the remaining wavelength band (RB pixel data).

  Thus, in the imaging system 10, the cover 12 having the same appearance color system is present on the structure outer surface 19 of the vehicle C as a structure to be installed, so that the installation location and the structure outside Differences from the surface 19 can be suppressed. For this reason, it can prevent that the improvement in the designability of the vehicle C becomes a hindrance.

  Further, in the imaging system 10, since the appearance color of the cover 12 is one of the systems in which the hue is roughly divided and set, the structure outer surface 19 when viewed from the outside with a simple configuration. The difference in hue with can be reduced. This means that it is much easier to equalize the system set by roughly dividing the hue as compared with the color completely matching the structure outer surface 19 of the structure to be installed. by.

  Further, in the imaging system 10, since five systems of purple, blue, green, yellow, and red are set as systems in the appearance color of the cover 12, all colors (light (electromagnetic wave)) except white and black are set. Any color in the visible region).

  In the imaging system 10, the imaging device 11 is covered with the external color cover 12 of the same system as the structure outer surface 19. Therefore, it is difficult to visually recognize the imaging device 11 at first glance. Therefore, it is possible to prevent the design of the vehicle C from being hindered from being improved.

  In the imaging system 10, the installation space 18 in which the imaging device 11 is installed is covered with the cover 12 having the same appearance color as that of the structure outer surface 19. Since it can be made difficult, it is possible to prevent the design of the vehicle C from being hindered from being improved.

  In the imaging system 10, since the cover 12 is provided so that the cover surface 12a of the cover 12 is connected to the structure outer surface 19 of the vehicle C as a structure to be installed, the structure outer surface 19, that is, the vehicle C The presence of the cover 12 can be made less noticeable. For this reason, it can prevent that the improvement in the designability of the vehicle C becomes a hindrance.

  Since the imaging system 10 makes it difficult to visually recognize the installation space 18 by covering with the cover 12, the installation space 18 is set from the viewpoint of eliminating the limitation of the visual field in the imaging device 11 (imaging optical system 20). Therefore, it is possible to acquire the entire range of the rear diagonally lower region of the vehicle C set as the photographing target without hindering improvement in the design of the vehicle C. This is because, in the case of the configuration in which the imaging device is arranged in the concave portion provided on the surface of the trunk or hatch, it is necessary to arrange the imaging device so as to be concealed by the concave portion and the trunk or hatch in order to make the imaging device inconspicuous.

  In the imaging system 10, the imaging device 11 is installed in the installation space 18 provided in the vehicle C as a structure to be installed, and the cover 12 is provided to cover the installation space 18 (the opening). The vehicle C can be provided in a state in which the imaging device 11 is protected while the field of view is not restricted.

  In the imaging system 10, the imaging device 11 is installed in the installation space 18 provided in the vehicle C as a structure to be installed, and the cover 12 is provided to cover the installation space 18 (the opening). Further, since a portion protruding from the vehicle C (its outer surface 19) is not configured, it is possible to prevent the vehicle C from being hindered from improving safety.

  In the imaging system 10, the imaging device 11 is installed in the installation space 18 provided in the vehicle C as a structure to be installed, and the cover 12 is provided to cover the installation space 18 (the opening). Since the structure (vehicle C) can be disposed even in a place without unevenness, it is possible to improve the degree of freedom of arrangement while facilitating securing the visual field. This is because, in the past, the unevenness of the vehicle C is often used in order to make the imaging device inconspicuous.

  In the imaging system 10, since the cover 12 has translucency that allows transmission of light (electromagnetic waves) in the entire visible region, a color image is acquired by the imaging device 11 (appropriate RGB pixel data is acquired). Can be generated).

  In the imaging system 10, the cover 12 has a transmission characteristic in which the residual transmittance in the remaining wavelength band other than the appearance transmittance in the outer wavelength band that forms the outer color is a constant value. The cover 12 can be formed of a general material having translucency. This is because a light-transmitting material generally has a color in which transmitted light that transmits natural light (white light) is equal to an appearance color.

  In the imaging system 10, the light receiving element portion 31 b corresponding to G, which is a component formed by light in the appearance wavelength band in the subject image, resulting from the provision of the cover 12 by the correction mechanism (the AGC circuit 43 in the first embodiment). Cancels the difference in intensity between the output signal (G pixel data) from and the output signal (RB pixel data) from the light receiving element portion 31b corresponding to RB, which is a component formed by light in the remaining wavelength band. Therefore, it is possible to appropriately acquire a color image of a region obliquely below the rear side of the vehicle C set as an imaging target without hindering improvement in the design of the vehicle C.

  In the imaging system 10, since the AGC circuit 43 in the imaging device 31 having a gain adjustment function is used as a correction mechanism and only the amplification value (gain) setting value is changed, a simple configuration can be achieved. .

  In the imaging system 10, the amplification amount (gain) of the AGC circuit 43 serving as a correction mechanism is set according to the bias in the transmission characteristics of the cover 12, so that the vehicle C set as an imaging target is diagonally below the rear side. The color image of the area can be acquired more appropriately. In particular, in the first embodiment, the amplification amount (gain) of the AGC circuit 43 is set by multiplying the basic setting value by a setting correction value that is a characteristic line indicating the reciprocal of the transmission characteristic of the cover 12 having a maximum value of 1. Therefore, the influence of the cover 12 can be canceled more effectively, and a color image can be acquired more appropriately.

  In the imaging system 10, the amplification amount (gain) of the AGC circuit 43 serving as a correction mechanism is set in consideration of the characteristics of the imaging apparatus 11 (mainly the transmission characteristics of the imaging optical system 20). It is possible to more appropriately acquire the color image of the region on the diagonally lower side of the vehicle C to be set.

  In the imaging system 10, the cover 12 has a transmission characteristic in which the residual transmittance in the remaining wavelength band other than the appearance transmittance in the outer wavelength band that forms the outer color is a constant value. By simply adjusting the relative intensity of the appearance wavelength band and the remaining wavelength band uniformly, the difference in intensity of the color components caused by providing the cover 12 can be canceled out.

  Since the imaging system 10 uses the AGC circuit 43 in the imaging device 31 having a gain adjustment function as a correction mechanism, an output signal output from the imaging device 31 (in the first embodiment, a Bayer array as an analog signal). (RGB pixel data) is not affected by the bias of the transmission characteristics of the cover 12 (corrected), so that the processing load on the signal processing circuit 41 can be reduced.

  In the imaging system 10, since the cover 12 has a light-transmitting property that allows light (electromagnetic waves) to be transmitted in the entire infrared region and visible region, even in a dark atmosphere such as at night, for example. An image can be acquired by the imaging device 11.

  In the imaging system 10, since the anti-fouling measures are taken on the cover surface 12a of the cover 12, it is possible to make it difficult for water or dust to adhere to the cover surface 12a. It is possible to acquire an image of the area on the lower rear side.

  Since the imaging system 10 can acquire the entire range of the region set as the imaging target without hindering the improvement of the design of the structure, it is used as an in-vehicle camera system to which the vehicle C is applied as the structure. It is suitable for.

  The rear vision support mechanism 80 that uses the imaging system 10 as an in-vehicle camera system acquires the entire range of the rear diagonally lower area of the vehicle C set as an imaging target without hindering improvement in the design of the vehicle C. Thus, it is possible to more appropriately assist the occupant to visually recognize the rear of the vehicle.

  Therefore, in the imaging system 10 according to the present invention, it is possible to provide the imaging device 11 while suppressing the occurrence of a difference in appearance from the peripheral structure without incurring a restriction on the visual field.

  In the first embodiment, the amplification amount (gain) of the AGC circuit 43 serving as the correction mechanism is set to relatively reduce the amplification amount (gain) in the high transmittance region in the transmission characteristic bias of the cover 12. However, as shown in FIG. 13, the setting correction value is a characteristic line indicating the reciprocal of the transmission characteristic of the cover 12, and the amplification amount (gain) in the low transmittance region is offset in the transmission characteristic bias of the cover 12. It may be relatively increased and is not limited to the first embodiment described above.

  Next, the imaging system 10B of Example 2 will be described with reference to FIG. The imaging system 10B according to the second embodiment is an example in which the configuration of a correction mechanism that cancels the influence of the transmission characteristics of the cover 12 is different from the imaging system 10 according to the first embodiment. Since the basic configuration of the imaging system 10B (rear-viewing support mechanism 80) of the second embodiment is the same as that of the imaging system 10 (rear-viewing support mechanism 80) of the first embodiment described above, the same configuration is used. Are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 14 is a block diagram similar to FIG. 7 showing an outline of the system configuration of the electronic circuit 40B of the imaging device 11B of the imaging system 10B.

  In the imaging system 10B according to the second embodiment, as illustrated in FIG. 14, the AGC circuit 43 is not provided in the imaging element 31B. That is, the image sensor 31B of the second embodiment does not have a gain adjustment function for adjusting the amplification amount (gain) of the output signal (RGB pixel data) from each light receiving element unit 31b corresponding to RGB. Accordingly, in the signal processing circuit 41B of the electronic circuit 40B, an AGC circuit 43B is provided, and an output ratio adjustment unit 47 is provided between the image generation unit 45 and the output conversion unit 46. The AGC circuit 43B has the same function as the AGC circuit 43 of the first embodiment. Further, the output ratio adjusting unit 47 uses an output signal (G pixel data) from the light receiving element unit 31b corresponding to G, which is a component formed by light in the appearance wavelength band, and light in the remaining wavelength band in the subject image. This constitutes a correction mechanism that cancels out the difference in intensity between the output signal (RB pixel data) from the light receiving element portion 31b corresponding to the formed RB. For this reason, in the electronic circuit 40B of the second embodiment, the amplification amount (gain) for each light receiving element portion 31b corresponding to RGB of the AGC circuit 43B is set as a basic setting.

  When the image data (color image data (image signal)) generated by the image generation unit 45 is input, the output ratio adjustment unit 47 first converts the image data into R image data, G image data, and B image data. Decompose. Thereafter, the output value of each of the RGB image data is multiplied by a setting correction value that is a characteristic line indicating the reciprocal of the transmission characteristic of the cover 12 with the maximum value being 1. In the second embodiment, as in the first embodiment, the cover 12 has a green appearance color that is the same system as that of the structural outer surface 19 (see FIG. 5 and the like), and the transmitted light that has been transmitted has an appearance color. As shown in FIG. 9, the transmission characteristics are biased. For this reason, in the output ratio adjustment unit 47, the set correction value described above is a residual wavelength whose appearance wavelength band (especially the wavelength band from 560 nm to 580 nm) is another wavelength band depending on the transmission characteristics of the cover 12. It is assumed that it is locally lower than the band (see FIG. 11). The output ratio adjustment unit 47 multiplies the set correction value by the output value of each RGB image data, generates color image data from each of the multiplied image data, and outputs the image data to the output conversion unit 46. Output.

  For this reason, in the electronic circuit 40B (signal processing circuit 41B), the image data generated by the image generating unit 45 is biased according to the transmission characteristics of the cover 12, and in the second embodiment, the image data is greenish overall. It is said that. The biased image data is output to the output conversion unit 46 after the output ratio adjustment unit 47 converts the image data into appropriate image data without bias. For this reason, in the imaging system 10B of the second embodiment, a white image (image data) is generated for a white object under natural light (white light).

  Since the imaging system 10B according to the second embodiment has basically the same configuration as that of the imaging system 10 according to the first embodiment, the same effects as in the first embodiment can be basically obtained.

  In addition, in the imaging system 10B according to the second embodiment, as the correction mechanism, only the output ratio adjustment unit 47 is provided in the electronic circuit 40B, so that the configuration can be simplified.

  In the imaging system 10B, the setting correction value for correcting the output value of each of the RGB image data in the output ratio adjustment unit 47 as a correction mechanism is set in the transmission characteristics of the cover 12 according to the bias. The influence of the cover 12 can be effectively canceled, and a color image can be acquired more appropriately.

  Further, in the imaging system 10B, the amplification amount (gain) of the AGC circuit 43B of the electronic circuit 40B is set to a basic setting in consideration of characteristics in the imaging apparatus 11B (mainly transmission characteristics of the imaging optical system 20). Since the output value of the RGB image data that has passed through the circuit 43B is corrected by the output ratio adjustment unit 47 as a correction mechanism, the color image in the diagonally lower area of the rear side of the vehicle C set as the photographing target is more appropriately displayed. Can be acquired.

  In the imaging system 10B, even if the imaging device 11B has the imaging element 31B that does not have the gain adjustment function, the influence of the cover 12 can be effectively canceled and a color image can be acquired more appropriately. .

  Therefore, in the imaging system 10B according to the second embodiment, the imaging device 11B can be provided while suppressing the occurrence of a difference in appearance from the surrounding structure without incurring a restriction on the visual field.

  In the second embodiment described above, the setting correction value of the output ratio adjustment unit 47 as the correction mechanism is set to relatively reduce the output value of the image data in the high transmittance region in the bias of the transmission characteristic of the cover 12. However, the set correction value is a characteristic line indicating the reciprocal of the transmission characteristic of the cover 12, and the output value of the image data in the low transmittance region is relatively increased in the bias of the transmission characteristic of the cover 12 ( 13), and is not limited to the second embodiment described above.

  In the second embodiment, the output ratio adjusting unit 47 is provided in the signal processing circuit 41B as a correction mechanism. However, the amplification amount (gain) of the AGC circuit 43B of the signal processing circuit 41B is set as the signal processing of the first embodiment. It may be configured to function as a correction mechanism by setting similarly to the circuit 41, and is not limited to the above-described second embodiment.

  Further, in the above-described second embodiment, the AGC circuit 43B is provided in the signal processing circuit 41B. However, the output ratio adjustment unit 47 is assumed not to be affected by the deviation of the transmission characteristics of the cover 12 (the correction is made). Therefore, the AGC circuit 43B may not be provided, and is not limited to the second embodiment described above. When the AGC circuit 43B is not provided, the setting correction value in the output ratio adjustment unit 47 is considered in consideration of characteristics (mainly transmission characteristics of the imaging optical system 20) in the imaging apparatus 11B in order to obtain a color image more appropriately. It is desirable to set.

  In the second embodiment described above, the image pickup device 31B of the image pickup apparatus 11B is not provided with a gain adjustment function. However, an image pickup device having a gain adjustment function may be used, and is limited to the second embodiment described above. Is not to be done.

  Next, an imaging system 10C according to the third embodiment will be described with reference to FIG. The imaging system 10C of the third embodiment is an example in which the configuration of the correction mechanism that cancels the influence of the transmission characteristics of the cover 12 is different from the imaging system 10 of the first embodiment and the imaging system 10B of the second embodiment. Since the basic configuration of the imaging system 10C (rear-viewing support mechanism 80) of the third embodiment is the same as that of the imaging system 10 (rear-viewing support mechanism 80) of the first embodiment described above, the imaging system 10C (rear-viewing support mechanism 80) has the same configuration. Are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 15 is a block diagram illustrating an outline of the system configuration of the imaging system 10C.

  An imaging system 10C according to the third embodiment includes an image processing mechanism 50 in addition to the imaging device 11C and the cover 12, as illustrated in FIG. The image pickup device 11C according to the second embodiment is mounted on the image pickup apparatus 11C. Accordingly, in the imaging system 10C, the signal processing circuit 41C of the electronic circuit 40C of the imaging apparatus 11C has an AGC circuit 43B and an A / D converter 44. That is, the signal processing circuit 41C amplifies the analog image signal (Bayer array RGB pixel data) input from the image sensor 31B to a predetermined value by the AGC circuit 43B, and the amplified analog signal is A / D. The converter 44 converts the RGB pixel data in the Bayer array into a digital signal and outputs it to the image processing mechanism 50. In the AGC circuit 43B of the third embodiment, the amplification amount (gain) for each light receiving element portion 31b corresponding to RGB is set as a basic setting.

  Based on the digital signal (RGB pixel data) output from the signal processing circuit 41C (electronic circuit 40C) of the imaging device 11C, the image processing mechanism 50 generates image data that cancels the influence of the bias on the transmission characteristics of the cover 12. Then, the image data is output. In the third embodiment, the image processing mechanism 50 includes an image generation unit 51, an output ratio adjustment unit 52, and an output conversion unit 53. The image generation unit 51 is the same as the image generation unit 45 (see FIG. 7) of the first embodiment. When RGB pixel data having a Bayer array converted into a digital signal is input, the image generation unit 51 is based on the RGB pixel data. Then, color component pixel data at all coordinate positions is generated by linear interpolation independently for each color of RGB, and the generated pixel data is appropriately corrected, and then image data is generated based on each pixel data. The image generation unit 51 outputs the generated image data to the output ratio adjustment unit 52.

  The output ratio adjustment unit 52 is the same as the output ratio adjustment unit 47 (see FIG. 14) of the second embodiment, and when image data (color image data (image signal)) is input, G image data and B image data are decomposed, and the output value of each of the RGB image data is multiplied by a setting correction value that is a characteristic line indicating the reciprocal of the transmission characteristic of the cover 12 with a maximum value of 1. Color image data is generated from the image data after the multiplication. Similar to the second embodiment, the setting correction value is more localized than the remaining wavelength band in which the external wavelength band (especially, the wavelength band from 560 nm to 580 nm) is another wavelength band depending on the bias in the transmission characteristics of the cover 12. It is assumed that it is lowered (see FIG. 11). For this reason, the output ratio adjustment unit 52 outputs the output signal (G pixel data) from the light receiving element unit 31b corresponding to G, which is a component formed by light in the appearance wavelength band, and the light in the remaining wavelength band in the subject image. It functions as a correction mechanism that cancels out the difference in intensity between the output signal (RB pixel data) from the light receiving element portion 31b corresponding to RB that is a component formed by. The output ratio adjustment unit 52 outputs the generated image data to the output conversion unit 53.

  The output converter 53 is the same as the output converter 46 (see FIG. 7) of the first embodiment, and converts the input image data into a predetermined signal and outputs it.

  Therefore, in the image processing mechanism 50, the image data generated by the image generation unit 51 based on the digital signal (RGB pixel data) output from the signal processing circuit 41C (electronic circuit 40C) of the imaging device 11C is stored in the cover 12. There is a bias according to the transmission characteristics, and in Example 3, the whole is greenish. The biased image data is output to the output conversion unit 53 after the output ratio adjustment unit 52 converts the image data to appropriate image data without bias. For this reason, in the imaging system 10C of the third embodiment, when a white object under natural light (white light) is acquired by the imaging device 11C through the cover 12, an image processing mechanism that acquires an output signal from the imaging device 11C 50 (output ratio adjustment unit 52) adjusts the intensity of the color component caused by the cover 12, and generates a white image (image data).

  Since the imaging system 10C according to the third embodiment has basically the same configuration as that of the imaging system 10 according to the first embodiment, the same effects as those in the first embodiment can be basically obtained.

  In addition, in the imaging system 10C of the third embodiment, an image based on a digital signal (RGB pixel data (output signal)) output from the imaging device 11C (signal processing circuit 41C (electronic circuit 40C)) is used as a correction mechanism. Since only the output ratio adjustment unit 52 is provided in the image processing mechanism 50 that generates data, the configuration can be simplified.

  Further, in the imaging system 10C, the setting correction value for correcting the output value of each of the RGB image data in the output ratio adjustment unit 52 as a correction mechanism is set according to the bias in the transmission characteristics of the cover 12. The influence of the cover 12 can be effectively canceled, and a color image can be acquired more appropriately.

  Further, in the imaging system 10C, the amplification amount (gain) of the AGC circuit 43B of the signal processing circuit 41C (electronic circuit 40C) of the imaging device 11C takes into consideration the characteristics in the imaging device 11C (mainly the transmission characteristics of the imaging optical system 20). Since the output value of each RGB image data that has passed through the AGC circuit 43B is corrected by the output ratio adjustment unit 52 of the image processing mechanism 50 as a correction mechanism, the vehicle set as the photographing target The color image of the area diagonally below C can be acquired more appropriately.

  In the imaging system 10C, even if the imaging device 11C includes the imaging device 31B that does not have the gain adjustment function, the influence of the cover 12 can be effectively canceled and a color image can be acquired more appropriately. .

  In the imaging system 10C, since the image processing mechanism 50 is provided separately from the imaging device 11C, the imaging device 11C can be made smaller. For this reason, attachment to the arbitrary positions of a structure (vehicle C in Example 3) can be made easy, and it can contribute by improvement in the design nature of a structure.

  Therefore, in the imaging system 10C according to the third embodiment, it is possible to provide the imaging device 11C while suppressing the appearance difference from the peripheral structure without causing limitation of the visual field.

  In the above-described third embodiment, the setting correction value of the output ratio adjustment unit 52 as the correction mechanism is set to relatively reduce the output value of the image data in the high transmittance region in the bias of the transmission characteristic of the cover 12. However, the set correction value is a characteristic line indicating the reciprocal of the transmission characteristic of the cover 12, and the output value of the image data in the low transmittance region is relatively increased in the bias of the transmission characteristic of the cover 12 ( 13), and is not limited to the third embodiment described above.

  In the third embodiment, the AGC circuit 43B is provided in the signal processing circuit 41C. However, the output ratio adjustment unit 52 of the image processing mechanism 50 is not affected by the bias of the transmission characteristics of the cover 12 ( Therefore, the AGC circuit 43B may not be provided, and is not limited to the above-described third embodiment. When the AGC circuit 43B is not provided, the setting correction value in the output ratio adjustment unit 52 is considered in consideration of the characteristics (mainly the transmission characteristics of the imaging optical system 20) in the imaging apparatus 11C in order to obtain a color image more appropriately. It is desirable to set.

  In the third embodiment described above, the image pickup device 31B of the image pickup apparatus 11C is not provided with a gain adjustment function. However, an image pickup device having a gain adjustment function may be used, and is limited to the second embodiment described above. Is not to be done.

  Next, an imaging system 10D of Example 4 will be described with reference to FIGS. The imaging system 10D according to the fourth embodiment is different from the imaging system 10 according to the first embodiment, the imaging system 10B according to the second embodiment, and the imaging system 10C according to the third embodiment in the configuration of the correction mechanism that cancels the influence of the transmission characteristics of the cover 12. It is a different example. Since the basic configuration of the imaging system 10D (backward vision support mechanism 80) according to the fourth embodiment is the same as that of the imaging system 10 (backward vision support mechanism 80) according to the first embodiment described above, the imaging system 10D (backward vision support mechanism 80) has the same configuration. Are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 16 is an explanatory diagram showing an outline of the configuration of the imaging system 10D. FIG. 17 is a graph showing the transmission characteristics of the bandpass filter 61, where the vertical axis indicates the ratio of transmitted light (electromagnetic wave) intensity with the maximum being 1 (transmittance of the bandpass filter 61), and the horizontal axis is the wavelength. (Nm).

  As illustrated in FIG. 16, the imaging system 10 </ b> D according to the fourth embodiment includes a band-pass filter 61 in addition to the imaging device 11 and the cover 12. Accordingly, in the imaging system 10D, the AGC circuit 43 of the imaging device 31 of the imaging device 11 has a basic setting of an amplification amount (gain) for each light receiving element portion 31b corresponding to RGB.

  The band pass filter 61 is provided on the photographing optical axis OA between the cover 12 and the imaging device 11. That is, in the imaging system 10 </ b> D, the imaging device 11 acquires light that has passed through the cover 12 and has passed through the bandpass filter 61. The bandpass filter 61 is set to cancel the influence of the bias on the transmission characteristics of the cover 12 while allowing the transmission of light (electromagnetic waves) in the entire infrared region and visible region. In the fourth embodiment, as shown in FIG. 17, the bandpass filter 61 has a characteristic line in which the transmittance with respect to the wavelength indicates the reciprocal of the transmission characteristic of the cover 12, and the appearance wavelength band (in particular, a wavelength of 560 nm to 580 nm). (Band) is locally lower (substantially half) than the remaining wavelength band, which is another wavelength band. The band-pass filter 61 relatively reduces light (electromagnetic waves) in a region with high transmittance due to uneven transmission characteristics of the cover 12. Therefore, the band-pass filter 61 functions as a correction mechanism that cancels out the difference in intensity between the component formed by the light in the appearance wavelength band and the component formed by the light in the remaining wavelength band in the subject image.

  As a result, the imaging device 11 can acquire light (electromagnetic waves) that has passed through the cover 12 and the bandpass filter 61 to cancel the deviation in the transmission characteristics of the cover 12. That is, the imaging system 10D generates a white image (image data) for a white object under natural light (white light).

  Since the imaging system 10D according to the fourth embodiment has basically the same configuration as that of the imaging system 10 according to the first embodiment, the same effects as in the first embodiment can be basically obtained.

  In addition, in the imaging system 10D according to the fourth embodiment, the bandpass filter 61 is simply provided between the cover 12 and the imaging device 11 as a correction mechanism, so that the configuration can be simplified.

  Further, in the imaging system 10D, the transmittance characteristic of the band-pass filter 61 as a correction mechanism is set in accordance with the bias of the transmission characteristic of the cover 12, so that the influence of the cover 12 can be effectively canceled out. A color image can be acquired more appropriately.

  Further, in the imaging system 10D, the amplification amount (gain) of the AGC circuit 43 of the imaging device 31 of the imaging device 11 takes into account the characteristics in the imaging device 11 (mainly the transmission characteristics of the imaging optical system 20 (see FIG. 4 etc.)). Since the imaging device 11 transmits the cover 12 and the bandpass filter 61 to obtain light (electromagnetic waves) that cancels the bias in the transmission characteristics of the cover 12, the imaging device 11 is used as an imaging target. It is possible to more appropriately acquire the color image of the region on the diagonally lower side of the vehicle C to be set.

  Therefore, in the imaging system 10D of the fourth embodiment, it is possible to provide the imaging device 11 while suppressing the appearance difference from the peripheral structure without causing the limitation of the visual field.

  In the above-described fourth embodiment, the band pass filter 61 as a correction mechanism is provided between the cover 12 and the imaging device 11, but the cover 12 and the imaging device 31 (see FIG. 4, etc.) in the imaging device 11. May be provided between any of the lenses 21a to 21f (see FIG. 4) in the optical element group 21 (imaging optical system 20) of the imaging device 11, for example. It may be provided between the element group 21 (imaging optical system 20) and the imaging element 31, and is not limited to the configuration of the fourth embodiment.

  In the above-described fourth embodiment, the image pickup device 31 having the gain adjustment function is used in the image pickup apparatus 11. However, the bandpass filter 61 is not affected by the bias of the transmission characteristics of the cover 12 (the correction is performed). Therefore, an image sensor having no gain adjustment function may be used, and the present invention is not limited to the fourth embodiment described above.

  In each of the above-described embodiments, the imaging systems 10, 10B, 10C, and 10D as examples of the imaging system according to the present invention have been described. However, the imaging optical system that forms a subject image and the imaging optical system form an image. An imaging system configured by installing an imaging device having an imaging element for obtaining a subject image on a structure, and having an appearance color of the same system as the structure outer surface of the structure and translucency An imaging system provided between the imaging optical system and a subject, which is provided on the structure by forming a flat surface that covers the imaging device and is continuous with the outer surface of the structure. There is no limitation to the above-described embodiments.

  In each of the above-described embodiments, five systems of purple, blue, green, yellow, and red are set as systems in the appearance color of the cover 12, but from the outside under natural light (white light). From the viewpoint of reducing the difference in hue from the outer surface 19 of the structure at the time of viewing, if the hue is roughly divided and set so as to be classified and indicated by the color (color) aspect, the color and number of classification May be set as appropriate, and is not limited to the above-described embodiments.

  Furthermore, in each of the above-described embodiments, the cover 12 is formed by adding a pigment having an appearance color to a transparent material such as a glass material, polycarbonate, or acrylic. However, when viewed from the outside, natural light (white light) If the color (system) is the same as when viewed through (), for example, the transparent material may be formed by vapor-depositing a transparent thin film having the appearance color. In addition, a transparent filter or cellophane, which is an appearance color, may be pasted, and is not limited to the above-described embodiments.

  In each of the above-described embodiments, the appearance color of the cover 12 is green. However, it may be any appearance color of the same system as the structure outer surface of the structure to be installed, and is limited to each of the above-described embodiments. It is not a thing.

  In each of the above-described embodiments, the imaging apparatuses 11, 11B, and 11C are set to have sensitivity to light (electromagnetic waves) in the infrared region (wavelength). What is necessary is just to have a sensitivity, and it is not limited to each above-mentioned Example.

  In each of the above-described embodiments, the cover 12 is allowed to transmit light (electromagnetic waves) in the entire infrared region (wavelength), but the wavelength band in which the imaging devices (11, 11B, 11C) have sensitivity. However, the present invention is not limited to the above-described embodiments.

In each of the above-described embodiments, a silica (SiO ₂ ) antifouling film is provided on the cover surface 12a of the cover 12. However, any antifouling measure that makes it difficult to attach water or dust can be used. Further, it may be one utilizing a hydrophilic action or one utilizing a water repellent action, and is not limited to the above-described embodiments.

  In each of the above-described embodiments, the imaging apparatuses 11, 11B, and 11C are configured as described above. However, the imaging apparatus includes an imaging optical system and an imaging element that acquires a subject image formed by the imaging optical system. And what is necessary is just to install in the structure as installation object, and it is not limited to each above-mentioned Example.

  In each of the above-described embodiments, the imaging systems 10, 10B, 10C, and 10D select the vehicle C as a structure to be installed, and are used as an in-vehicle camera system to configure the rear view assisting mechanism 80 in the vehicle C. However, it can be widely applied as, for example, an in-vehicle camera system as a drive recorder for recording the situation of an accident in a vehicle, a surveillance camera system mounted on an ATM, etc., and is limited to the above-described embodiments. Is not to be done.

  In each of the above-described embodiments, the RGB signal is converted into the NTSC or PAL signal by the output conversion unit (46, 53) after adjusting the gain or adjusting the image. The output conversion unit may convert the RGB signal into an NTSC or PAL signal and perform color image adjustment on the converted signal. Even if it is such a structure, the same result as each Example can be obtained.

  In each of the above-described embodiments, the upper limit of the wavelength is set to about 800 nm in FIGS. 8, 10, and 12. However, in order to increase the sensitivity at night, the sensitivity on the long wavelength side of the sensor (imaging device 31) is increased ( The upper limit of the obtainable wavelength band may be increased), and is not limited to the above-described embodiments. In the case of such a configuration, it is desirable to set the transmission characteristics with respect to the wavelength of the cover 12 in accordance with the sensitivity setting in the sensor (image sensor 31).

  As described above, the imaging system of the present invention has been described based on each embodiment. However, the specific configuration is not limited to each embodiment, and design changes and additions are possible without departing from the gist of the present invention. Etc. are allowed.

10, 10B, 10C, 10D Imaging system 11, 11B, 11C Imaging device 12 Cover 12a Cover surface 19 Structure outer surface 20 Imaging optical system 31 Imaging element 43 AGC circuit 47 (as an example of correction mechanism) 47 (as example of correction mechanism) Output ratio adjusting unit 52 (as an example of a correction mechanism) output ratio adjusting unit 61 band pass filter (as an example of a correction mechanism) OA photographing optical axis C vehicle

JP 2007-223342 A

Claims (13)

An imaging system comprising an imaging optical system for forming a subject image and an imaging device having an imaging device for obtaining a subject image formed by the imaging optical system, installed in a structure,
A cover having a translucent appearance color of the same system as the structure outer surface of the structure,
The imaging system is provided between the imaging optical system and a subject, and is provided on the structure body so as to cover the imaging device and form a continuous plane on the outer surface of the structure.   The imaging system according to claim 1, wherein the cover allows transmission of light in a wavelength band in which the imaging element has sensitivity.   The cover is characterized in that the residual transmittance of light in a remaining wavelength band other than the outer wavelength band is lower than the outer transmittance of light in the outer wavelength band that forms the outer color. The imaging system according to 2. The imaging system according to claim 3,
The imaging apparatus further comprises a correction mechanism that cancels a difference in intensity between a component formed by the light in the appearance wavelength band and a component formed by the light in the remaining wavelength band in the subject image. system.   The imaging system according to claim 4, wherein the correction mechanism adjusts an intensity of an output signal output for each color component from the imaging element. The imaging apparatus includes an image generation unit that generates image data based on an output signal output from the imaging element,
The imaging system according to claim 4, wherein the correction mechanism adjusts an intensity of an image signal for each color component in the image data generated by the image generation unit. The imaging system according to claim 4,
Furthermore, an output signal from the imaging device is input, and an image generation unit that generates image data based on the output signal is provided.
The imaging system, wherein the correction mechanism adjusts an intensity of an image signal for each color component in the image data generated by the image generation unit.   The imaging system according to claim 4, wherein the correction mechanism is a band-pass filter that is provided between the cover and the imaging device and cancels a difference between the appearance transmittance and the residual transmittance. .   The correction mechanism is characterized in that, based on the appearance transmittance, the residual transmittance, and the transmittance of the imaging optical system, the imaging device has an equal intensity over the entire wavelength band in which the imaging element has sensitivity. The imaging system according to any one of claims 4 to 8.   The imaging system according to claim 2, wherein the imaging element has sensitivity in a visible region and an infrared region.   The imaging system according to any one of claims 1 to 10, wherein an antifouling film is formed on a cover surface of the cover that is continuous with the outer surface of the structure.   An in-vehicle camera system using the imaging system according to any one of claims 1 to 11. A vehicle on which the in-vehicle camera system according to claim 12 is mounted.