Inside mirror structure with built-in camera

Abstract

[Problem] In a configuration in which the optical axis of an infrared camera is disposed obliquely with respect to the normal direction of the plate surface of a mirror element, ghosts caused by an image of an internal structure generated in an image captured by the infrared camera by irradiation of strong external light through the mirror element to the internal structure of an inside mirror, the ghost image which is included in the ghost image and is caused by the height difference part between the lens and the back plate is not obvious. As a result, the visibility of the captured image is improved, and the recognition accuracy of the image recognition process based on the captured image is improved. [Solution] A flat surface portion (77a) and a concave surface portion (77b) are formed on a back plate (76) disposed behind a mirror element (78). At least a portion of the lens exposure opening (82) is formed on an inclined surface of the concave surface portion (77b), the inclined surface being inclined with respect to the flat surface portion (77a). A lens (72) of the infrared camera (64) is disposed so that an optical axis (L1) is inclined with respect to the normal direction of the planar portion (77a) while imitating the lens exposure opening (82).

Description

Technical Field

[0001] The present invention relates to a structure of an interior rearview mirror with a built-in camera, in which an infrared camera is arranged behind a mirror element that reflects visible light and transmits infrared light. In particular, the present invention is used to improve the visibility of an image captured by the infrared camera or to improve the recognition accuracy of the image captured by image recognition processing based on the image by making the ghost image of the internal structure of the interior rearview mirror less obvious. Background Art

[0002] Various technologies have been proposed, such as using a mirror element that reflects visible light and transmits infrared light, placing an infrared camera behind the mirror element, and allowing an image of the interior of the vehicle illuminated by infrared lighting to pass through the mirror element and be photographed by the infrared camera to monitor the driver or the rear seat (or the rear seat and the rear outside the vehicle), etc. For example, Patent Document 1 below proposes an interior rearview mirror with a built-in camera that is configured in a manner capable of monitoring the driver's situation. Fig.11 Patent Document 1 Figure 2 The rearview mirror with a built-in camera shown in the figure (partially corrected figure). In the rearview mirror 10, a mirror element 26 that reflects visible light and transmits infrared light is arranged in a state of being maintained in a ring 28 mounted on the front surface of the shell 12 at the opening portion of the front surface of the shell 12. A substrate 16 is provided in the internal space of the shell 12 so as to face the back of the mirror element 26. An infrared camera 20 is mounted on the back of the substrate 16, and an infrared illuminator 24 composed of infrared LEDs is mounted on the front surface of the substrate 16. The lens 22 of the infrared camera 20 is exposed from the lens exposure port 18 formed in the substrate 16 and faces the back of the mirror element 26. The infrared light emitted from the infrared illuminator 24 is irradiated toward the driver's face through the mirror element 26. The image of the driver's face irradiated by the infrared light is captured by the infrared camera 20 through the mirror element 26. The driver's situation is monitored based on the image captured by the infrared camera 20. In the interior rearview mirror 10, a shading component 30 is arranged between the infrared illuminator 24 and the lens 22 to prevent stray light (white blur) in the captured image caused by the infrared light emitted from the infrared illuminator 24 directly entering the lens 22 of the infrared camera 20 or entering the lens 22 of the infrared camera 20 after being reflected by the mirror element 26, a shading component 30 is arranged between the infrared illuminator 24 and the lens 22.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-136760 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In an interior rearview mirror with a built-in camera, in order to capture the monitored object at the center of the camera's field of view, there is a case where the camera optical axis is configured to be tilted relative to the normal direction of the mirror element's plate surface. That is, in the case of using the camera image for monitoring the rear seat (or the rear seat and the rear outside the vehicle), the camera optical axis is configured to be tilted in the left-right direction relative to the normal direction of the mirror element's plate surface in the direction opposite to the driver's side (the left direction in the case of right-hand steering). In addition, in the case of using the camera image for monitoring the driver, the camera optical axis is configured to be tilted in the left-right direction relative to the normal direction of the mirror element's plate surface in the direction toward the driver's side (the right direction in the case of right-hand steering). In addition, in the up-down direction, there is also a case where the camera optical axis is configured to be tilted downward relative to the normal direction of the mirror element's plate surface.

[0008] In the rearview mirror 10 described in Patent Document 1, the optical axis of the infrared camera 20 is arranged in the direction of the normal to the plate surface of the mirror element 26. According to the experiment conducted by the inventors, it is known that if the optical axis of the infrared camera 20 is arranged to be tilted relative to the normal to the plate surface of the mirror element 26, a problem may occur. That is, if the optical axis of the infrared camera 20 is tilted, for example, in the left-right direction, the lens 22 is necessarily tilted in the same direction, and therefore, the lens 22 is arranged in a manner that has an angle relative to the plate surface of the substrate 16. As a result, the height difference between at least one of the left and right ends of the lens 22 and the front surface of the substrate 16 adjacent to the end becomes larger than the height difference in the case where there is no such tilt. On the other hand, if strong external light (including infrared light) such as the headlights of the rear vehicle or the sunlight at a low position in the morning and evening passes through the mirror element 26 and enters the interior of the rearview mirror 10, the image of the internal structure of the rearview mirror 10 illuminated by the external light is reflected by the back of the mirror element 26 and captured by the infrared camera 20, causing ghost images to appear in the captured image. In particular, if the optical axis of the infrared camera 20 is arranged to be tilted, resulting in a larger height difference between the lens 22 and the substrate 16, the ghost image caused by the height difference portion becomes obvious in the ghost image caused by the internal structure of the rearview mirror 10 generated by the image captured by the infrared camera 20. As a result, in the use of displaying the image captured by the infrared camera 20 on a display so that the driver or the like can visually recognize it (for example, the use of the driver or the like to monitor the rear seat and the situation behind the vehicle), the visibility of the captured image may be reduced. In addition, in the use of performing image recognition processing on the image captured by the infrared camera 20 for automatic monitoring (for example, the use of monitoring the driver's drowsy driving), the recognition accuracy may be reduced. In view of such a problem, if the infrared camera 20 is tilted together with the substrate 16, the height difference between the lens 22 and the substrate 16 does not increase, so the ghost image caused by the height difference portion included in the ghost image can be suppressed. However, if the substrate 16 is tilted, the dimension of the rearview mirror 10 in the front-to-back direction (thickness direction) becomes larger due to the tilted configuration of the substrate 16. In addition, in the structure where the infrared illuminator 24 is disposed on the substrate 16 and the infrared light is irradiated toward the mirror element 26 as in the rearview mirror 10 described in Patent Document 1, if the substrate 16 is tilted, the gap between the mirror element 26 and the substrate 16 is enlarged on one side of the rearview mirror 10, making it difficult for the shading member 30 to shield the infrared light irradiated from the infrared illuminator 24.

[0009] The present invention aims to solve the problem of ghost images caused by the image of the internal structure in the image captured by the infrared camera, which is caused by the image of the internal structure, in a structure in which the optical axis of the infrared camera is arranged obliquely relative to the normal direction of the plate surface of the mirror element. That is, the present invention can suppress the ghost image caused by the height difference between the lens and the back plate, without arranging the back plate (mirror holder, substrate, plate hiding the internal structure of the rearview mirror, etc.) facing the back of the mirror element and arranged behind the mirror element as a whole, without arranging the back plate (mirror holder, substrate, plate hiding the internal structure of the rearview mirror, etc.) facing the back of the mirror element as an entirety. In this way, the present invention provides an internal rearview mirror structure with a built-in camera, which seeks to improve the visibility of the captured image, or improve the recognition accuracy of the captured image based on the image recognition processing of the captured image.

[0010] Solutions for solving problems

[0011] The present invention comprises: a shell; a mirror element, which has an optical property of reflecting visible light and transmitting infrared light, and is arranged at a position to block the opening of the front surface of the shell; a back plate, which is accommodated in the internal space of the shell surrounded by the shell and the mirror element, and is arranged behind the mirror element facing the back of the mirror element; and an infrared camera, which is arranged at a position behind the back plate in the internal space of the shell, so that the lens is exposed toward the back of the mirror element from a lens exposure port formed on the back plate, and receives infrared light incident through the mirror element, the front surface of the back plate having a plane portion arranged parallel to the plate surface of the mirror element (for example, the front surface or the back surface of the mirror element or a surface between them) and a concave portion formed by being recessed relative to the plane portion, at least a part of the lens exposure port is formed on the concave portion and is inclined relative to the plane portion, and the lens of the infrared camera is arranged so that the optical axis is inclined relative to the normal direction of the plane portion in imitation of the lens exposure port. Furthermore, in the present invention, the plate surface of the mirror element is arranged parallel to the plane portion, which is not limited to the case where the plate surface of the mirror element is arranged completely parallel to the plane portion, and includes the case where the plate surface of the mirror element is arranged approximately parallel to the plane portion. Furthermore, in the present invention, the inclination direction of the optical axis of the lens relative to the normal direction of the plane portion is not limited to the two directions of the upper and lower sides and the left and right sides of the plate surface of the mirror element set as the rearview mirror, and can also be set to any direction.

[0012] According to the invention, the optical axis of the infrared camera can be arranged to be tilted relative to the normal direction of the plate surface of the mirror element without tilting the entire back plate relative to the mirror element, and the height difference between the lens of the infrared camera and the back plate can be suppressed from increasing. Therefore, the size of the rearview mirror in the front-to-back direction can be suppressed from increasing, and at the same time, the ghost image caused by the height difference between the lens and the back plate contained in the ghost image caused by the image of the internal structure of the rearview mirror generated in the image captured by the infrared camera due to strong external light can be suppressed. As a result, the visibility of the captured image can be improved, or the recognition accuracy of the captured image can be improved based on the image recognition processing of the captured image.

[0013] In the present invention, the back plate can be configured to have a structure in which the entire circumference of the concave portion is surrounded by the plane portion. In this case, the entire circumference of the concave portion is surrounded by the plane portion, so that the warping and bending of the back plate caused by the concave portion can be suppressed. In addition, when the mirror element is configured in a manner that is closely arranged with the plane portion, the entire circumference of the outer peripheral edge of the concave portion can be sealed by the mirror element, and dust, dirt, etc. can be suppressed from entering the concave portion.

[0014] In the present invention, the rear panel can be configured as a component in which the plane portion and the concave portion are integrally configured. In this case, compared with a case in which the plane portion and the concave portion are configured as independent components, the number of components can be reduced, and the assembly of the rear panel to the interior rearview mirror becomes easier.

[0015] In the present invention, the back panel can also be configured to be composed of a combination of parts that are independently configured by the planar portion and the concave portion. In this case, when a plurality of back panels having different shapes of concave portions are prepared, each back panel can be configured by combining parts having the same planar portion and parts having different concave portions. In addition, in this case, the parts that constitute the concave portion and the parts that constitute the front portion of the housing of the infrared camera can also be integrally configured. In this case, the number of parts can be reduced compared to a case where the parts that constitute the concave portion and the parts that constitute the front portion of the housing of the infrared camera are configured as independent parts. In addition, the parts with the planar portion and the parts with the concave portion remain unconnected to each other when assembled to the rearview mirror, or can be connected to each other using an adhesive, a coating, or the like.

[0016] The rear panel can be configured to constitute a mirror holder for holding the mirror element, for example. In this case, the mirror element and the mirror holder can be bonded to each other at the plane portion. In addition, the rear panel can be configured to constitute a substrate for mounting the infrared camera, and the substrate does not constitute a mirror holder for holding the mirror element. In addition, the rear panel can be configured to constitute a plate for hiding the internal structure of the rearview mirror.

[0017] The back plate can be made of, for example, plastic, reinforced plastic, metal, etc. The front surface of the back plate can be dark in color (black, dark gray, etc.).

[0018] The present invention can further include infrared lighting, which is stored in the internal space of the shell, so that infrared light is irradiated toward the back of the mirror element and the infrared light is radiated toward the external space of the shell through the mirror element. The infrared lighting can be configured, for example, to be arranged behind the back plate and irradiate toward the back of the mirror element through an irradiation window formed on the back plate, or to be mounted on the front surface of the back plate and irradiate toward the back of the mirror element. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an exploded perspective view of a rearview mirror with a built-in camera according to Embodiment 1 of the present invention.

[0020] Figure 2 Yes means Figure 1 A diagram showing an example of the spectral characteristics of a mirror element in FIG.

[0021] Figure 3A yes Figure 1 The front view of the mirror holder in FIG. 1 also shows the configuration of the infrared camera lens and infrared LED.

[0022] Figure 3B yes Figure 1 A perspective view of the mirror holder in FIG. Figure 3A A diagram observed near the viewing position.

[0023] Figure 3C yes Figure 1 A perspective view of the mirror holder in FIG. Figure 3A The diagram is observed near the B viewing position.

[0024] Figure 3D yes Figure 1 A perspective view of the mirror holder in FIG. Figure 3A Observation diagram near the C viewing position.

[0025] Figure 4 It is assembled Figure 1 In the state of the rearview mirror with a built-in camera Figure 3A A sectional view taken from the DD direction.

[0026] Figure 5A Yes means Figure 1 A front view of an interior rearview mirror with a built-in camera in an assembled state.

[0027] Figure 5B yes Figure 5A A cross-sectional view from the EE direction.

[0028] Figure 5C yes Figure 5A A cross-sectional view of the FF direction (shown in an enlarged manner).

[0029] Fig. 6A This is a photograph showing an image captured by the built-in infrared camera when the camera-built-in rearview mirror according to the first embodiment of the present invention is irradiated with external light generated by a tungsten halogen lamp from the front of the rearview mirror.

[0030] Figure 6B This is a comparative example in which the concave portion of the front surface of the mirror holder of the interior rearview mirror with a built-in camera in embodiment 1 of the present invention is set to a box shape (a shape with no inclined surface and the bottom surface as a whole consisting of a plane parallel to the flat portion) over the entire circumference, and shows a photograph of an image captured by the built-in infrared camera when the interior rearview mirror is irradiated with external light generated by a halogen tungsten lamp from the front side.

[0031] Figure 7 This is an exploded perspective view of a rearview mirror with a built-in camera according to a second embodiment of the present invention.

[0032] Figure 8 It is assembled Figure 7 In the state of the rearview mirror with a built-in camera Figure 4 A sectional view cut at a position corresponding to the cutting position of the sectional view.

[0033] Fig. 9 This is an exploded perspective view of a rearview mirror with a built-in camera according to a third embodiment of the present invention.

[0034] Fig.10 It is a plan cross-sectional view showing a cross section of a rearview mirror with a built-in camera according to a fourth embodiment of the present invention.

[0035] Fig.11 It indicates that Patent Document 1 Figure 2 A plan view (partially modified view) of a cross section of the described rearview mirror with a built-in camera. DETAILED DESCRIPTION

[0036] The following describes an embodiment of the present invention. In the following embodiments, for a rearview mirror with a built-in camera (hereinafter referred to as "rearview mirror") and its components, the up, down, left, and right directions refer to the corresponding directions when the mirror surface of the rearview mirror is observed from the front when the rearview mirror is mounted on a vehicle. That is, when the mirror surface of the rearview mirror is observed from the front when the rearview mirror is mounted on a vehicle, the up, down, left, and right directions of the rearview mirror and its components are represented by the directions that become up, down, left, and right for the rearview mirror and its components. In addition, for the rearview mirror and its components, the "front surface" refers to the surface facing the viewpoint side when the mirror surface of the rearview mirror is observed from the front, and the "back surface" refers to the surface facing the side opposite to the viewpoint side.

[0037] Implementation Method 1

[0038] Embodiment 1 of the present invention will be described. Here, a rear panel is constituted by a mirror holder that holds a mirror element. Figure 1 The rearview mirror 40 of embodiment 1 of the present invention is shown in a disassembled state. The rearview mirror 40 is for right-hand drive vehicles and is designed to monitor the rear seats (or the rear seats and the rear outside the vehicle). The rearview mirror for left-hand drive vehicles has a structure that is symmetrical to the rearview mirror 40. The rearview mirror 40 has a support rod 50 and a mirror body 51. The upper end of the support rod 50 is mounted on the top surface or the front windshield surface at the upper front part of the vehicle interior and the left and right center position. The mirror body 51 is mounted and supported on the lower end of the support rod 50 in a tiltable manner (i.e., in a manner that the mirror angle can be adjusted). The mirror body 51 has: a shell 42, which constitutes an outer shell; and a support member 52, a camera module 60, and a mirror module 73, which are stored in the internal space 45 of the shell 42.

[0039] In the mirror body 51, the shell 42 is made of plastic and is composed of three parts: a main body 44, a cover 46, and a ring 48. The cover 46 is installed on the back of the main body 44 by claw engagement, and the ring 48 is installed on the front surface of the main body 44 by claw engagement, so that these three parts are assembled to form the shell 42. The support member 52 is made of a metal die-casting or an integrally formed product of reinforced plastic, and is formed in a horizontally long plate shape. The support member 52 is connected to the lower end of the support rod 50 on its back side by a pivot 54 in a tiltable manner. An opening portion (opening portion 56 of the main body 44 and opening portion 58 of the cover 46) for passing the connecting portion is formed on the back side of the shell 42.

[0040] The camera module 60 is fixedly mounted at the left side of the front surface of the support member 52 by screws or the like. The camera module 60 includes an infrared camera 64 and an infrared illuminator 68 mounted on the front surface of the infrared camera 64. The infrared illuminator 68 is composed of a plurality of (four in this case) infrared LEDs arranged in a horizontal row with their respective light emitting surfaces facing the front of the infrared camera 64. The lens barrel 70 protrudes forward from the front surface of the infrared camera 64. A lens 72 is mounted on the opening at the front end of the lens barrel 70.

[0041] A mirror module 73 is arranged on the front surface of the support member 52. The mirror module 73 has a structure in which a mirror element 78 is joined and held on the front surface 77 of a mirror holder 76 by double-sided tape or the like. The mirror holder 76 is made of an integrally molded product of plastic or reinforced plastic. The mirror element 78 is composed of a well-known dielectric multilayer mirror in which a dielectric multilayer film 75b (an optical film of a multilayer structure) is formed on the back side of a transparent glass substrate 75a (the surface facing the front surface 77 of the mirror holder 76). The mirror element 78 has the optical properties of a so-called cold mirror that reflects visible light and transmits infrared light (near-infrared light). In this embodiment, the mirror element 78 is configured as a so-called prismatic reflector with an anti-glare function. Therefore, the longitudinal section of the transparent glass substrate 75a perpendicular to the surface has a wedge shape that is thicker at the top and thinner at the bottom (refer to Figure 5C ). The driver manually switches the knob (not shown) to tilt the entire mirror body 51 in the vertical direction relative to the support rod 50, thereby switching the vertical angle of the mirror element 78. As a result, the driver can drive and operate the vehicle during the day while visually recognizing the rear reflection image of the vehicle formed by the mirror surface of the dielectric multilayer film 75b. In addition, the driver can drive and operate the vehicle at night while visually recognizing the anti-glare rear reflection image of the vehicle formed by the glass surface of the front surface 78a of the mirror element 78. An example of the spectral characteristics of the mirror element 78 is shown in Figure 2 This is the characteristic at an incident angle of 5 degrees. The reflection characteristic is the characteristic of the mirror surface of the dielectric multilayer film 75b. The mirror element 78 is adhered to the mirror holder 76 by double-sided tape or the like so that the back surface 78b formed with the dielectric multilayer film 75b faces the front surface 77 of the mirror holder 76 and is held by the mirror holder 76.

[0042] Figure 1The interior rearview mirror 40 is assembled, for example, in the following order. The mirror element 78 is attached to the front surface 77 of the mirror holder 76 by double-sided tape or the like to assemble the mirror module 73. Next, the camera module 60 is mounted at a predetermined position on the left side of the front surface of the support member 52 by screw fixing or the like. The support member 52 is accommodated in the internal space 45 of the main body 44 by passing the support rod 50 through the opening 56 of the main body 44 and the opening 58 of the cover 46. The assembled mirror module 73 is covered on the front surface of the support member 52. At this time, the lens barrel 70 of the camera module 60 is shallowly inserted into the lens exposure port 82 formed in the mirror holder 76. The camera module 60 and the mirror holder 76 are not directly connected to each other. At this time, from the driver's point of view, the optical axis L1 of the lens 72 is arranged slightly outward (leftward) and slightly tilted downward relative to the normal direction of the plane portion 77a of the front surface 77 of the mirror holder 76. In addition, at this time, the four infrared illuminators 68 are arranged at positions facing the infrared light irradiation windows 84 formed in the mirror holder 76. Four screws 80 are inserted into the four through holes 79 formed at the four corners of the main body 44 from the back side, and the screws 80 are passed through the through holes 81 at the four corners of the support member 52 and screwed into the threaded holes (not shown) formed in the protrusions 83 at the four corners of the back side of the mirror holder 76. Thus, the main body 44, the support member 52, and the mirror holder 76 with the mirror element 78 mounted thereon are assembled to each other while the support member 52 is sandwiched and fastened by the main body 44 and the mirror holder 76. The ring 48 is inserted and mounted on the front surface of the main body 44 by claw engagement, and the cover 46 is inserted and mounted on the back side of the main body 44 by claw engagement. The opening 48a of the ring 48 (the opening of the shell 42) is blocked by the mirror element 78, and the internal space 45 of the shell 42 is surrounded by the shell 42 and the mirror element 78. The inner rearview mirror 40 is assembled through the above steps.

[0043] Reference Figure 3A to Figure 3DThe structure of the mirror holder 76 is described below. The mirror holder 76 is made of an integrally molded product of plastics such as PE, ASA, PP or reinforced plastics such as PAGF (glass fiber reinforced nylon resin). The colors of the above materials are all dark (black, dark gray, etc.). Alternatively, the mirror holder 76 can also be formed by darkly painting the front surface of the integrally molded product formed by metal die casting or metal stamping. By making the front surface of the mirror holder 76 dark, the ghost image in the captured image can be made less obvious. In addition, by forming the front surface of the mirror holder 76 into a rough surface, the ghost image can be made further less obvious. The front surface 77 of the mirror holder 76 has a plane portion 77a and a concave portion 77b formed by being recessed relative to the plane portion 77a. A lower wall 77c is formed on the entire periphery of the outer periphery of the plane portion 77a. The entire periphery of the plane portion 77a is surrounded by the wall 77c. The mirror element 78 is arranged on the inner peripheral side surrounded by the wall 77c. The wall 77c plays a role in positioning the mirror element 78 relative to the front surface 77 and maintaining the position of the positioning. A concave shape 77d is formed in the right area of ​​the front surface 77 to prevent the warping and bending of the mirror holder 76 and to increase the strength and rigidity of the mirror holder 76. The entire circumference of the concave shape 77d is surrounded by the plane portion 77a. The concave surface portion 77b is formed in the left area of ​​the front surface 77. The entire circumference of the concave surface portion 77b is surrounded by the plane portion 77a. The mirror holder 76 and the mirror element 78 are bonded to each other using a double-sided tape or the like in the substantially entire area of ​​the plane portion 77a. In particular, the entire circumference of the outer peripheral portion of the plane portion 77a surrounded by the wall 77c is bonded to the mirror element 78. The concave surface portion 77b and the concave shape 77d are both arranged on the inner circumference side of the front surface 77 surrounded by the plane portion 77a, so that the entire circumference of the outer peripheral portion of the front surface 77 of the mirror holder 76 surrounded by the wall 77c is constituted by the plane portion 77a. Therefore, the deformation of the mirror holder 76 caused by the formation of the concave surface 77b and the concave shape 77d can be suppressed by the flat surface 77a formed on the entire circumference of the front surface 77. In addition, the entire circumference of the concave surface 77b is closed by the mirror element 78, so that dust, dirt, etc. can be suppressed from entering the concave surface 77b.

[0044] The concave portion 77b is described below. The cross section of the concave portion 77b (a cross section formed by a horizontal plane passing through the center of the lens 72 and perpendicular to the flat portion 77a) has a substantially V-shape (see Figure 3B to Figure 3D , Figure 4 The longitudinal section of the concave portion 77b (a cross-sectional plane formed by a vertical plane passing through the center of the lens 72 and orthogonal to the flat portion 77a) is formed in a box shape (see Figure 5C). However, the longitudinal section of the concave portion 77b can also be formed into a roughly V-shape. The entire circumference of the concave portion 77b can also be formed into a cone shape, a bowl shape, etc. The concave portion 77b has a left inclined surface 86a and a right inclined surface 86c due to the V-shape of the cross section. A bottom surface 86b that is curved into a concave shape in the left and right directions is formed in the valley bottom portion between the left and right inclined surfaces 86a, 86c. The bottom surface 86b smoothly connects the left and right inclined surfaces 86a, 86c. Assuming that there is no curved bottom surface 86b and the left and right inclined surfaces 86a, 86c are directly connected to each other at the lower ends of the left and right inclined surfaces 86a, 86c, a "turn" consisting of a sharp V-shape is generated between the lower ends. As a result, it is possible that a strong brightness difference (the difference in brightness between adjacent areas in one image, i.e., a steep brightness gradient) may be generated in the ghost image (ghost image caused by the image of the internal structure of the rearview mirror 40) of the image captured by the infrared camera 64 due to the bend. In contrast, the bend is eliminated by smoothly connecting the lower ends of the left and right inclined surfaces 86a and 86c using the curved bottom surface 86b. As a result, it is possible to suppress the strong brightness difference in the ghost image of the image captured by the infrared camera 64. If the brightness difference of the ghost image is suppressed, even if a ghost image is generated, the possibility of mistaking the brightness difference for a part of the image of the subject can be reduced. In addition, since the left and right inclined surfaces 86a and 86c are inclined, the height difference between the boundary portion of the concave portion 77b and the plane portion 77a in the left and right directions becomes smaller than the height difference when the left and right inclined surfaces 86a and 86c are not inclined. Therefore, it is possible to suppress the ghost image caused by the height difference portion contained in the image captured by the infrared camera 64 from being obvious. In addition, by making the corners of the upper end and the lower end of the height difference at the boundary portion rounded, the brightness difference of the ghost image caused by the height difference portion included in the captured image can be alleviated.

[0045] The lens exposure opening 82 is formed from the right side inclined surface 86c to the bottom surface 86b. Therefore, the lens exposure opening 82 opens in a direction slightly inclined to the left relative to the normal direction of the flat surface 77a, following the right side inclined surface 86c. As the lens exposure opening 82 is arranged in such an inclined manner, the lens 72 of the infrared camera 64 is arranged so that the optical axis L1 is slightly inclined to the left relative to the normal direction of the flat surface 77a, following the lens exposure opening 82 (see FIG. 1 ). Figure 4 , Figure 5B). In the mirror holder 76, at a position above the lens exposure port 82, an infrared light irradiation window 84 is formed in a manner extending in the left-right direction from the concave portion 77b to the flat portion 77a. The light-emitting surfaces of the four infrared illuminators 68 face the infrared light irradiation window 84 from the back side of the mirror holder 76. The opening of the infrared light irradiation window 84 is further bent downward from its right end portion and formed to extend downward. In the concave portion 77b, a light-shielding wall 88 is protrudingly formed in a manner passing between the lens exposure port 82 and the infrared light irradiation window 84 and surrounding the lens exposure port 82. The light-shielding wall 88 is formed to prevent the infrared light emitted from the infrared light irradiation window 84 from being directly incident on the lens 72 of the infrared camera 64 exposed to the lens exposure port 82, or from being reflected by the back side 78b of the mirror element 78 and incident on the lens 72. A light shielding seal 90 (eg, made of black sponge) is attached to the top surface of the light shielding wall 88 as required to more reliably seal the gap between the top surface and the back surface 78 b of the mirror element 78. Figure 4 ).

[0046] Figure 4 In the state where the rearview mirror 40 is installed, Figure 3A Cut at the DD viewing position Figure 3A A cross section of the structure. Figure 4 In the cross-sectional view of FIG. 8 , the right side portion of the lens exposure opening 82 is cut at the position of the light shielding wall 88, so the right side inclined surface 86c is not clearly shown, but the lens 72 of the infrared camera 64 is arranged so that the optical axis L1 is slightly inclined to the left relative to the normal direction of the plane portion 77a in imitation of the right side inclined surface 86c. In other words, the lens exposure opening 82 opens in a direction inclined toward the inclination direction of the optical axis L1 of the lens 72 relative to the normal direction in the left and right direction of the two directions of the up and down and the left and right directions that are orthogonal to the normal direction of the plane portion 77a. The concave surface 77b is formed in a manner that a predetermined viewing angle of the infrared camera 64 can be obtained in the left and right direction (that is, in a manner that does not cause light shielding of the captured image due to the concave surface 77b). In addition, the concave surface 77b is formed in a manner that a predetermined viewing angle of the infrared camera 64 can also be obtained in the up and down direction (which can be narrower than the viewing angle in the left and right direction). Assuming that the lens 72 whose optical axis L1 is inclined with respect to the flat surface portion 77a is arranged on the flat surface portion 77a, the height difference between the lens 72 and the mirror holder 76 (more precisely, the height difference between the left-right end of the front surface of the lens 72 and the flat surface portion 77a of the front surface 77 of the mirror holder 76) becomes larger at the position where the lens 72 faces the lens exposure port 82. In contrast, the lens 72 is arranged on the right side inclined surface 86c ( Figure 3A to Figure 3D), therefore, at the position where the lens 72 faces the lens exposure port 82, the height difference between the lens 72 and the mirror holder 76 (to be precise, the height difference between the left-right end of the front surface of the lens 72 and the concave portion 77b of the front surface 77 of the mirror holder 76) S( Figure 4 ) can be unchanged. Therefore, even if strong external light is irradiated to the inner rearview mirror 40 and a ghost image is generated in the captured image of the infrared camera 64 due to the image of the internal structure of the inner rearview mirror 40 (here, the image of the front surface 77 of the lens 72 and the mirror holder 76 around it), the ghost image caused by the height difference portion (the portion where the height difference S exists) contained in the ghost image can be suppressed from being obvious. As a result, the possibility of mistaking the ghost image contained in the ghost image and caused by the lens and the height difference portion for a part of the image of the subject is reduced. Therefore, the visibility of the captured image and the recognition accuracy of the image recognition processing based on the captured image can be improved.

[0047] Will assemble Figure 1 The state of the inner rearview mirror 40 is shown in Figure 5A to Figure 5C middle. Figure 5A is the main view, Figure 5B yes Figure 5A The cross-sectional view from the EE direction, Figure 5C yes Figure 5A Cross-sectional view from the FF direction.

[0048] Among them, a light-shielding seal 90 made of black sponge or the like is pasted on the top surface of the light-shielding wall 88 to more reliably seal the gap between the top surface and the back surface 78b of the mirror element 78. In addition, a bandpass filter 92 that allows a wavelength range corresponding to the sensitivity wavelength of the infrared camera 64 (for example, near-infrared light with a wavelength of 900nm to 1000nm) to pass is pasted on the back surface 78b of the mirror element 78 and the area surrounded by the light-shielding wall 88. By configuring the bandpass filter 92, a captured image with a clear shape of the subject can be obtained. In this embodiment, as Figure 5C As shown, the optical axis L1 of the infrared camera 64 is arranged to be slightly inclined downward in the vertical direction relative to the normal direction of the concave portion 77b of the front surface 77 of the mirror holder 76. Figure 5CAs shown, the concave portion 77b of the front surface 77 of the mirror holder 76 is arranged parallel to the front surface 78a of the mirror element 78 in the up-down direction. However, the concave portion 77b can also be formed to have an inclined surface that is inclined relative to the normal direction of the planar portion 77a in the up-down direction in the same way as the left-right direction, imitating the inclination of the optical axis L1 in the up-down direction. Alternatively, the entire circumference of the concave portion 77b can be configured as a conical surface or a bowl surface. In this way, by making the lens exposure opening 82 open in the up-down and left-right directions in a direction inclined toward the inclination direction of the optical axis L1 of the lens 72 (ideally, by forming the lens exposure opening 82 in a manner such that the plane to which the opening of the lens exposure opening 82 belongs is orthogonal to the optical axis L1), the height difference S ( Figure 4 ).

[0049] Figure 5A to Figure 5C The interior rearview mirror 40 shown is used as follows in a state where it is set on the front windshield or the top of the vehicle. The driver manually tilts the mirror body 51 relative to the support rod 50 to adjust the mirror element 78 to a mirror angle that can visually identify the rear of the vehicle. At this time, the optical axis L1 of the infrared camera 64 is slightly downward relative to the horizontal direction of the rear of the vehicle, and the infrared camera 64 can capture the rear seat (or the rear seat and the rear outside the vehicle) in the field of view. The viewing angle of the infrared camera 64 is also set in a manner with a certain degree of margin in the up and down directions. Therefore, even if the mirror body 51 is tilted in the up and down directions by switching between the non-anti-glare mode and the anti-glare mode, the infrared camera 64 can capture the rear seat (or the rear seat and the rear outside the vehicle) in the field of view. With the mirror angle adjusted, the driver can drive the vehicle while confirming the situation behind the vehicle using the reflected image of the mirror element 78 (in non-anti-glare mode, it is a reflected image formed by the dielectric multilayer film 75b, and in anti-glare mode, it is an anti-glare reflected image formed by the glass surface of the front surface 78a of the mirror element 78). When monitoring the rear seat (or the rear seat and the rear outside the vehicle), the on / off switch of the monitoring device equipped with the infrared camera 64 and the infrared lighting 68 is connected. As a result, the infrared camera 64 and the infrared lighting 68 are started. As a result, the infrared lighting 68 emits infrared light (near infrared light), and the infrared camera 64 starts shooting. The infrared light emitted from the infrared lighting 68 passes through the infrared light irradiation window 84 of the mirror holder 76 and is radiated toward the rear seat to the external space of the shell 42 through the mirror element 78. The image of the scene (subject) including the rear seat irradiated by the infrared light is photographed by the infrared camera 64 through the mirror element 78. The photographing signal is displayed on a display installed in the driver's seat, for example. The driver can drive while observing the displayed image and monitoring the situation of passengers in the rear seats, etc. In addition, the photographing signal can also be recorded in a driving recorder.

[0050] The image captured by the infrared camera 64 is described below. Fig. 6A The infrared camera 64 shows an image captured when external light generated by the halogen tungsten lamp H is irradiated onto the inner rearview mirror 40 from the front side of the inner rearview mirror 40 . Figure 6B For a comparative example in which the concave portion 77b of the front surface 77 of the mirror holder 76 of the inner rearview mirror 40 is set to a box shape (without an inclined surface, and the bottom surface as a whole is composed of a plane parallel to the flat portion 77a) over the entire circumference, an image captured by the infrared camera 64 when the outer light generated by the halogen tungsten lamp H is irradiated from the front of the inner rearview mirror 40 is shown. Fig. 6A (Implementation method 1), Figure 6B In any of the (comparative examples), the external light irradiated to the interior rearview mirror 40 is irradiated to the front surface 77 of the mirror holder 76 through the mirror element 78, and the external light reflected by the mirror holder 76 is reflected by the mirror surface composed of the dielectric multilayer film 75b on the back surface 78b of the mirror element 78 and received by the infrared camera 64, so that a ghost image caused by the image of the front surface 77 of the mirror holder 76 is generated in the captured image. In particular, in Figure 6B In the comparative example, at the left-right end position of the lens 72, a ghost image G (white blur) is strongly visible due to the height difference between the lens 72 and the mirror holder 76 (here, the bottom surface of the concave surface 77b without the inclined surface). Fig. 6A In Embodiment 1, at the end position of the lens 72 in the left-right direction, the height difference S ( Figure 4 ) is smaller than that of the comparative example, so the ghost image G caused by the height difference portion is not conspicuous. Fig. 6A (Implementation 1), and Figure 6B Compared with the comparative example, the possibility of mistaking the ghost image G caused by the height difference portion included in the ghost image as a part of the image of the subject can be reduced. As a result, the visibility of the captured image and the recognition accuracy of the image recognition processing based on the captured image can be improved.

[0051] Implementation Method 2

[0052] Embodiment 2 of the present invention will be described. Figure 7 The inner rearview mirror 94 of the second embodiment of the present invention is shown in a disassembled state. The inner rearview mirror 94 has a split structure in which the mirror holder 76 (rear panel) of the inner rearview mirror 40 of the first embodiment is provided. The structure other than this is the same as that of the inner rearview mirror 40 of the first embodiment. The same reference numerals are used for the same parts in the second embodiment as in the first embodiment, and the description thereof is omitted.

[0053] exist Figure 7In the embodiment, the mirror holder 76 is divided into a mirror holder main body 76-1 and a concave surface forming piece 76-2. The concave surface forming piece 76-2 is attached to the front surface of the camera module 60 by using a double-sided tape, an adhesive, or the like. An opening 98 is formed in the mirror holder main body 76-1 in accordance with the shape of the concave surface forming piece 76-2. When the rearview mirror 94 is mounted, the concave surface forming piece 76-2 is fitted into the opening 98 of the mirror holder main body 76-1 without generating a large gap. Figure 8 The mirror holder 76 is mounted on the mirror holder 76. Figure 4 The position corresponding to the cutting position of the cross-sectional view (equivalent to Figure 3A The concave portion 77b of the second embodiment has a surface shape substantially the same as the surface shape of the concave portion 77b of the first embodiment. Figure 8 In the embodiment, the gap 100 between the mirror holder main body 76-1 and the concave surface portion forming piece 76-2 is maintained as it is, but the gap 100 may be sealed with a dark-colored (black, dark gray, etc.) adhesive or paint.

[0054] Implementation Method 3

[0055] Embodiment 3 of the present invention will be described. Fig. 9 The inner rearview mirror 101 of the third embodiment of the present invention is shown in a disassembled state. The inner rearview mirror 101 is formed by integrally forming the concave surface component piece 76-2 at the front part of the housing of the camera module 60 in the inner rearview mirror 94 of the second embodiment. In other words, the concave surface component piece 76-2 is formed so as to also serve as the front part of the housing of the camera module 60. The structure other than this is the same as that of the inner rearview mirror 94 of the second embodiment. The same reference numerals are used for the same parts in the third embodiment as those in the second embodiment, and the description thereof is omitted.

[0056] exist Fig. 9 In the embodiment, the front portion 61a of the plastic or reinforced plastic housing 61 (camera housing of the infrared camera 64) of the camera module 60 is formed with a concave portion forming piece 76-2' by integral molding. An opening portion 98 corresponding to the shape of the concave portion forming piece 76-2' is formed in the mirror holder body 76-1. When the rearview mirror 101 is assembled, the concave portion forming piece 76-2' is embedded in the opening portion 98 of the mirror holder body 76-1 without generating a large gap. At this time, the concave portion 77b and the lens 72 are arranged to be the same as those of the embodiment 2. Figure 8 On the top surface of the light shielding wall 88 of the concave portion forming sheet 76-2', a light shielding seal member (same as Figure 8The gap between the mirror holder body 76-1 and the concave portion forming piece 76-2' (with the same Figure 8 The gap 100 is the same as that of the conventional method, or it can be sealed with a dark-colored (black, dark gray, etc.) adhesive or paint as needed.

[0057] Implementation Method 4

[0058] Embodiment 4 of the present invention is shown in Fig.10 This is to apply the present invention to Fig.11 The rearview mirror 102 is configured to monitor the driver's situation. Fig.11 The same reference numerals are used for the same parts. Among them, the back plate is constituted by the substrate 16. In the rearview mirror 102, the mirror element 26 has the optical characteristics of a so-called cold mirror that reflects visible light and transmits infrared light (near infrared light). The mirror element 26 is held by the ring 28 constituting the front part of the shell 12 and is installed on the front surface of the shell 12. As a result, the opening 32 of the front surface of the shell 12 is blocked by the mirror element 26. In the internal space 34 of the shell 12, a substrate 16 is arranged behind the mirror element 26 in a manner facing the back of the mirror element 26. The substrate 16 is fixed by screws in a posture parallel to the mirror element 26 and supported by a plurality of protrusions 36 protruding from the inner peripheral surface of the shell 12. The substrate 16 does not have the function of a mirror holder for holding the mirror element 26. The front surface 17 of the substrate 16 has a plane portion 17a arranged parallel to the plate surface of the mirror element 26, and a concave portion 17b formed by being recessed relative to the plane portion 17a. The concave portion 17b can be formed into a cone shape, a bowl shape, etc., for example, over the entire circumference. A through hole constituting a lens exposure port 18 is formed on an inclined surface 19 of the concave portion 17b that is inclined relative to the plane portion 17a. An infrared camera 20 is mounted on the back of the substrate 16, and an infrared lighting 24 composed of an infrared LED is mounted on the front surface of the substrate 16. The lens 22 of the infrared camera 20 is exposed from the lens exposure port 18 and faces the back of the mirror element 26. The lens 22 of the infrared camera 20 is arranged in a manner that the optical axis L1 is tilted toward the direction of the driver's face relative to the normal direction of the plane portion 17a, in imitation of the inclined surface 19 formed with the lens exposure port 18. A light shielding member 30 is sandwiched between the mirror element 26 and the substrate 16 in a manner that surrounds the concave portion 17b. The light shielding member 30 prevents stray light (white blur) of the captured image from being generated by the infrared light emitted from the infrared illuminator 24 directly entering the lens 22 of the infrared camera 20 or entering the lens 22 of the infrared camera 20 after being reflected by the mirror element 26. The infrared light emitted from the infrared illuminator 24 is irradiated toward the driver's face through the mirror element 26. The image of the driver's face irradiated by the infrared light is captured by the infrared camera 20 through the mirror element 26. The driver's situation is monitored based on the captured image.

[0059] according to Fig.10 In the rearview mirror 102, the lens 22 is arranged on the inclined surface 19 of the concave surface 17b, which is inclined in the same direction as the optical axis L1. Therefore, the height difference S between the lens 22 and the substrate 16 (the height difference between the end of the lens 22 in the left-right direction and the concave surface 17b) can be not increased. Therefore, even if strong external light is irradiated to the rearview mirror 102 and a ghost image caused by the image of the internal structure of the rearview mirror 102 (here, the image of the front surface 17 of the lens 22 and the substrate 16 around it) is generated in the image captured by the infrared camera 20, the ghost image caused by the height difference portion (the portion where the height difference S exists) contained in the ghost image can be suppressed from being obvious. As a result, the possibility of mistaking the ghost image caused by the lens and the height difference portion contained in the ghost image for a part of the image of the subject is reduced, so that the visibility of the captured image and the recognition accuracy of the image recognition processing based on the captured image can be improved.

[0060] In addition, the mirror elements 26 and 78 of the above-mentioned embodiments are composed of plane mirrors, but the mirror elements 26 and 78 can also be composed of convex mirrors. In the case where the mirror elements 26 and 78 are composed of convex mirrors, the back plate 16 and 76 can also be composed of any one of a flat plate and a convex plate imitating the convex surface of the mirror elements 26 and 78. In addition, in the above-mentioned embodiments, the infrared illuminator 24 and 68 is set to emit infrared light through the mirror elements 26 and 78, but the infrared illuminator 24 and 68 can also be configured to emit infrared light in a manner that does not pass through the mirror elements 26 and 78. In addition, in the above-mentioned embodiments 1 to 3, the infrared camera 64 is mounted and supported on the support member 52, but instead, the infrared camera 64 can also be directly mounted and supported on the shell 42. In addition, in the above-mentioned embodiment 1, the infrared camera 64 is mounted and supported on the support member 52, but instead, the infrared camera 64 can also be mounted and supported on the mirror holder 76. In the first to third embodiments, the mirror element 78 is mounted and supported on the main body 44 side of the housing 42 . Alternatively, the mirror element 78 may be mounted and supported on the ring 48 side of the housing 42 similarly to the fourth embodiment.

[0061] Description of Reference Numerals

[0062] 12. Shell; 16. Base plate (back plate); 17. Front surface of base plate; 17a. Plane portion; 17b. Concave portion; 18. Lens exposure opening; 19. Inclined surface inclined relative to the plane portion; 20. Infrared camera; 22. Lens; 24. Infrared illumination; 26. Mirror element; 28. Ring; 30. Light shielding member; 32. Opening portion of the front surface of the shell; 34. Internal space of the shell; 36. Protrusion; 40. Internal rearview mirror with built-in camera; 42. Shell; 44. Main body; 45. Internal space of the shell; 46. Cover; 48. Ring; 48a. Ring , an opening of the housing (an opening of the front surface of the housing); 50, a supporting rod; 51, a mirror body; 52, a supporting member; 54, a pivot; 56, an opening of the back of the body; 58, an opening of the back of the cover; 60, a camera module; 61, a housing of the camera module; 61a, a front portion of the housing of the camera module; 64, an infrared camera; 68, an infrared illuminator; 70, a lens barrel; 72, a lens; 73, a mirror module; 75a, a transparent glass substrate; 75b, a dielectric multilayer film; 76, a mirror holder (back panel); 76-1, a mirror holder body; 76-2, Concave portion forming piece; 76-2', concave portion forming piece formed integrally with the front portion of the housing of the camera module; 77, front surface of the mirror holder; 77a, plane portion; 77b, concave portion; 77c, wall; 77d, concave shape; 78, mirror element; 78a, front surface of the mirror element (plate surface of the mirror element); 78b, back surface of the mirror element (plate surface of the mirror element); 79, through hole; 80, screw; 81, through hole; 82, lens exposure port; 83, protrusion; 84, infrared light irradiation window; 86a, left inclined surface; 86b, curved bottom surface; 86 c. Right inclined surface; 88. Light-shielding wall; 90. Light-shielding seal; 92. Bandpass filter; 94. Interior rearview mirror with built-in camera; 98. Opening of the mirror holder body; 100. Gap between the mirror holder body and the concave portion constituting the sheet; 101. Interior rearview mirror; 102. Interior rearview mirror; L1. Optical axis of the lens of the infrared camera; H. Halogen tungsten lamp; G. Ghost image at the lens exposure port caused by the height difference between the lens of the infrared camera and the back panel; S. Height difference between the lens of the infrared camera and the back panel at the lens exposure port.

Claims

1. An interior rearview mirror structure with a built-in camera, comprising: shell; a mirror element having an optical property of reflecting visible light and transmitting infrared light, and arranged at a position to block the opening of the front surface of the housing; a back plate which is accommodated in an inner space of the housing surrounded by the housing and the mirror element, and is arranged behind the mirror element facing the back surface of the mirror element; and an infrared camera, which is arranged in the inner space of the shell at a position behind the back plate, so that a lens is exposed from a lens exposure port formed in the back plate toward the back side of the mirror element, and receives infrared light incident through the mirror element, The front surface of the rear plate has a flat surface portion arranged parallel to the plate surface of the mirror element and a concave surface portion formed by being recessed relative to the flat surface portion. The lens exposure port is formed at least partially on an inclined surface of the concave surface portion and inclined relative to the planar surface portion. The lens of the infrared camera is arranged such that the optical axis is inclined relative to the normal direction of the planar portion in accordance with the lens exposure port.

2. The rearview mirror structure with a built-in camera according to claim 1, wherein: The back plate has a structure in which the entire circumference of the concave surface portion is surrounded by the planar portion.

3. The rearview mirror structure with a built-in camera according to claim 1, wherein: The back plate is configured as a component in which the flat surface portion and the concave surface portion are integrally configured.

4. The rearview mirror structure with a built-in camera according to claim 1, wherein: The rear plate is formed by a combination of parts in which the planar portion and the concave portion are independently formed.

5. The structure of the inner rearview mirror with a built-in camera according to claim 4, wherein: The parts constituting the concave portion are composed of parts different from the parts constituting the front portion of the housing of the infrared camera, and are mounted on the front portion of the housing of the infrared camera.

6. The rearview mirror structure with a built-in camera according to claim 4, wherein: The parts constituting the concave surface portion are integrally formed with the parts constituting the front portion of the housing of the infrared camera.

7. The rearview mirror structure with a built-in camera according to any one of claims 1 to 6, wherein: The rear plate constitutes a mirror holder that holds the mirror element.

8. The rearview mirror structure with a built-in camera according to claim 7, wherein: The mirror element and the rear plate are bonded to each other at the planar portion.

9. The rearview mirror structure with a built-in camera according to any one of claims 1 to 6, wherein: The rear plate constitutes a substrate on which the infrared camera is mounted, and the substrate does not constitute a mirror holder for holding the mirror element.

10. The rearview mirror structure with a built-in camera according to any one of claims 1 to 6, wherein: The camera-embedded rearview mirror structure further includes a support member, which is arranged behind the back plate in the internal space of the shell so as to face the back surface of the back plate and is mounted on the shell. The infrared camera is mounted on the support.

11. The rearview mirror structure with a built-in camera according to any one of claims 1 to 6, wherein: The interior rearview mirror structure with a built-in camera also has infrared lighting, which is accommodated in the internal space of the shell, so that infrared light is irradiated toward the back side of the mirror element and the infrared light is radiated toward the external space of the shell through the mirror element. The infrared lighting is arranged behind the back panel, so that the infrared light is irradiated toward the back side of the mirror element through an irradiation window formed on the back panel.

Images