Abstract:
A camera built-in rearview mirror is presented which includes an opening made on an under portion of a mirror housing, a camera built in the mirror housing having a lens facing the opening, and a transparent cover for closing the opening that the lens of the camera faces. It has a feature that the camera is mounted in the mirror housing attachably thereto or detachably therefrom. In this way, the rearview mirror allows the easier assembling and disassembling of the camera in the mirror housing and positioning of the camera with the opening. It can protect against dirt sticking to the lens and the occurrence of wind noise securely. Also when the mirror housing suffers from damages, the rearview mirror allows reuse of the camera, thereby contributing to a cost reduction in mirror housing replacement.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a camera built-in rearview mirror, which is applied to such as a side mirror or a door mirror of a vehicle.  
         BACKGROUND OF THE INVENTION  
         [0002]    An exterior mirror mounted on the front side of a vehicle such as an automobile, especially the one on the passenger-seat side, a door mirror for example, is likely to have a dead angle zone in the area right under the door mirror to the vicinity of the front wheel side, thereby causing a poor field of view.  
           [0003]    Japan Laid-Open Patent 2000-16181 (hereinafter referred to as the prior art 1) discloses a door mirror having a small camera which is installed inside a mirror housing and oriented toward the ground. Japan Laid-Open Patent 2000-62531 (hereinafter referred to as the prior art 2) discloses a door mirror having a small camera installed outside a mirror housing. Japan Laid-Open Patent 2000-168440 (hereinafter referred to as the prior art 3) discloses a door mirror having a small camera installed inside a mirror housing. Also Japan Laid-Open Patent 10-208198 (hereinafter referred to as the prior art 4) discloses a door mirror having a small camera which is installed inside a mirror housing and oriented toward the ground.  
           [0004]    The door mirrors described in the prior arts improve a field of view with a small camera by monitoring of the front, side and rear as well as the lower portion of a vehicle.  
           [0005]    The aforementioned conventional rearview mirrors, for example, one described in the prior art 1 has the problem that dirt is likely to stick to the exposed camera lens, even if a visor-like dirt protector is disposed in front of the lens relative to the vehicular traveling direction on the under surface of the mirror housing. It will lead to a deterioration of image acquisition performance and quality of acquired images, thereby making it impossible to maintain a high visibility over the long term. Furthermore, the exposed camera lens creates a large wind noise during vehicular travel.  
           [0006]    The rearview mirror of the prior art 2 has also the problem that dirt is likely to stick to the camera lens since the camera is mounted on the external surface of the mirror housing. It will result in a deterioration of image acquisition performance and quality of the acquired image and make it impossible to maintain a high visibility over the long term.  
           [0007]    The rearview mirror of the prior art 3 requires an accuracy for positioning of the camera with the opening made on the mirror housing during the camera installation, since the camera is firmly secured to the inner surface of the mirror housing. Thus, it will not only complicate the process while the camera is installed in the mirror housing but also require the installation of a transparent cover to close the opening of the housing at a different manufacturing step.  
           [0008]    The rearview mirror of the prior art 4 presents the difficulty in assembling and disassembling of the camera and lens since both are installed in the mirror housing. Furthermore, when the mirror housing experiences damage, it will inevitably sacrifice the camera and lens. When the mirror housing is replaced, the camera and lens cannot be reused, which results in a cost increase in replacement.  
           [0009]    The conventional camera built-in rearview mirrors are configured so that the edge of the opening is flush with that of the transparent cover. When it is used for the exterior mirror of a vehicle, for example, it is therefore likely to create a wind noise since the wind, which flows in the opposite direction of vehicular travel, is caught in the gap between the transparent cover and the opening.  
           [0010]    The object of the present invention to assess the problems described above is to provide a camera built-in rearview mirror, which presents the following features. The rearview mirror is capable of maintaining a long-term high visibility of the area covering at least the lower portion of a vehicle and the vicinity of the forward wheel by acquiring clear images. It allows the easier assembling and disassembling of the camera in the mirror housing and positioning of the camera with the opening. It protects against the dirt sticking to the lens and the occurrence of wind noise securely. Also when the mirror housing suffers from damages, the rearview mirror allows reuse of the camera, thereby contributing to a cost reduction in mirror housing replacement.  
         SUMMARY OF THE INVENTION  
         [0011]    The present invention to assess the problems described above provides a camera built-in rearview mirror having an opening which is made on an under portion of a mirror housing, a camera built in the mirror housing whose lens faces the opening and a transparent cover for closing the opening which the lens of the camera faces, wherein the camera is mounted in the mirror housing attachably thereto or detachably therefrom.  
           [0012]    The camera built-in rearview mirror presents the easier assembly such as assembling and dissembling of the camera in the mirror housing and positioning of the camera with the opening since the opening made on the mirror housing can be closed by the transparent cover while the camera is installed in the mirror housing. Replacement of the camera can be conducted easily since it is installed in the mirror housing attachably thereto or detachably therefrom. It also permits reuse of the camera, which is removed from the mirror housing when it is damaged. Since the lens having protection with the transparent cover is not exposed, it is possible to prevent soiling of the lens. In this way, a high visibility can be maintained over a long term by obtaining clearer images covering the lower portion of the vehicle and the vicinity of the front wheel.  
           [0013]    The present invention also provides a camera built-in rearview mirror in which a camera and a transparent cover are integrated into a first camera module.  
           [0014]    The camera built-in rearview mirror according to the present invention allows the opening made on the mirror housing to be closed by the transparent cover while the camera is installed in the mirror housing. Positioning of the camera with the opening of the mirror housing can be conducted easily in parallel with closing of the opening with the transparent cover, and thereby assembling of the camera and transparent cover with the mirror housing can be much simplified.  
           [0015]    The present invention still provides a camera built-in rearview mirror wherein a shielding element and a transparent cover surround the neighborhood of the lens of a camera to define a closed space.  
           [0016]    The camera built-in rearview mirror improves visibility by rendering acquired images clearer since the undesired incident light is prevented from entering the camera lens. In addition, visibility deterioration due to soiling of the lens can be securely prevented since dust and water will not intrude the periphery of the camera lens. The transparent cover and the shielding element can prevent the light, which enters the opening of the mirror housing through the transparent cover, from leaking out of the gap between the mirror and the plane of opening of the mirror housing. On the other hand, the light entering the same gap will not penetrate the shielding element.  
           [0017]    The present invention yet provides a camera built-in rearview mirror wherein a transparent cover and a shielding element are combined integrally.  
           [0018]    The camera built-in rearview mirror allows mounting of the shielding element while the camera is being installed in the mirror housing or the opening of the mirror housing is being closed with the transparent cover. Thus, assembling of the shielding element into the mirror housing can be performed more easily.  
           [0019]    The present invention further provides a camera built-in rearview mirror wherein a camera is supported elastically through a support element provided in a mirror housing.  
           [0020]    The camera built-in rearview mirror enables absorption of the vibration transmitted to the camera from the mirror housing during vehicular travel with elastic support of the camera inside the mirror housing. It can prevent image blur caused by vibration of the camera. Serious damage of the expensive camera can be prevented since the protection of the camera is enhanced by an impact absorbing effect exerted by the elastic support of the camera, even if the mirror housing is damaged. Thus, visibility deterioration due to unclear images caused by the camera vibration during vehicular travel is prevented and reuse of the camera can be put into practice. A cost reduction can be attained since the monetary loss associated with mirror housing replacement is minimized. The camera module, the integrally combined camera and transparent cover, which is elastically secured in the mirror housing, absorbs the dimensional errors associated with the parts of the camera module, thereby improving the positioning accuracy.  
           [0021]    The present invention still further provides a camera built-in rearview mirror wherein a gap is provided between a camera and a support element.  
           [0022]    The camera built-in rearview mirror increases the elastic holding force at the fastening point between the camera module, the camera and transparent cover integrally combined, and the support element, thereby promoting elasticity of the support element and allowing the easier positioning of the camera module. And serious damage of the camera is prevented by the enhanced protection effect even if the mirror housing is damaged. With elastic support of the camera in the mirror housing, the vibration of the camera can be absorbed more efficiently. Thus, visibility deterioration due to unclear images caused by the camera vibration during vehicular travel can better be prevented.  
           [0023]    The present invention yet further provides a camera built-in rearview mirror wherein a support element is made of a synthetic resin of plate-like shape.  
           [0024]    The camera built-in rearview mirror increases the elastic holding force at the fastening point between the camera module, the camera and transparent cover integrally combined, and the support element assisted by elasticity of the support element, thereby promoting the elasticity of the support element and allowing the easier positioning of the camera module. With the protection effect against the shock acting on the camera enhanced by the gap between the camera and support element, serious damage of the camera can be prevented securely even though the mirror housing is damaged. Absorption of the camera vibration can be more efficiently performed with the elastic support of the camera in the mirror housing. Thus, visibility deterioration due to unclear images caused by the camera vibration during vehicular travel can much better be prevented.  
           [0025]    As another feature, the present invention provides a camera built-in rearview mirror, wherein a plurality of luminous bodies are disposed on the under portion in a mirror housing, and wherein light of the luminous bodies irradiates an imaging area taken by a camera through a transparent cover.  
           [0026]    The camera built-in rearview mirror enhances a visibility by improving the quality of acquired images while a vehicle passing through a tunnel or running at night, especially.  
           [0027]    As still another feature, the present invention provides a camera built-in rearview mirror wherein a camera, a transparent cover and luminous bodies are integrated into a second camera module.  
           [0028]    The camera built-in rearview mirror enables mounting of the luminous bodies and closing of the opening of the mirror housing with the transparent cover while installing the camera into the mirror housing. Positioning of the camera with the opening of the mirror housing can be performed easily in parallel with closing of the opening with the transparent cover. Thus, assembling of the camera, the transparent cover and the luminous bodies with the mirror housing will be more easily conducted. In addition, the rearview mirror enhances a visibility by improving the quality of acquired images while a vehicle passing through a tunnel or running at night, especially.  
           [0029]    As yet another feature, the present invention provides a camera built-in rearview mirror, wherein a front edge of a transparent cover lying forward relative to a vehicle running direction is configured stepwise lower than a corresponding front edge of an opening, and a rear edge of the transparent cover lying backward relative to the vehicle running direction is configured stepwise higher than a corresponding rear edge of the opening.  
           [0030]    The camera built-in rearview mirror, when it is used for a vehicle exterior mirror for example, can prevent a wind noise since a wind flowing in the opposite direction of vehicular travel is not caught in the gap between the transparent cover and the opening. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0031]    [0031]FIG. 1 is a front view showing an example of mounting of the camera built-in rearview mirror on a door mirror vehicle according to the first embodiment, seeing from the vehicle rear.  
         [0032]    [0032]FIG. 2 is a plan view showing mounting of the rearview mirror on a door mirror vehicle.  
         [0033]    [0033]FIG. 3 is an enlarged cross-sectional side view showing mounting of the camera in the mirror housing taken along the line III-III in FIGS. 1 and 2.  
         [0034]    [0034]FIG. 4 is an enlarged cross-sectional side view showing mounting of the camera in the mirror housing taken along the line IV-IV in FIGS.  1 - 3 .  
         [0035]    [0035]FIG. 5 is an enlarged exploded perspective view seeing from under showing the configuration before inserting of the camera into the mirror housing without the mirror.  
         [0036]    [0036]FIG. 6 is an enlarged exploded perspective view seeing from above showing the configuration after inserting of the camera into the mirror housing without the mirror.  
         [0037]    [0037]FIG. 7 is an enlarged cross-sectional side view showing mounting of the camera built-in rearview mirror in the mirror housing according to the second embodiment. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0038]    The embodiment of the present invention will now be described referring to the accompanying drawings.  
         [0039]    As shown in FIGS. 1 and 2, a door mirror  1  of the present invention is mounted on a front door D 1  of driver seat and a front door D 2  of passenger seat of a vehicle A, respectively. As shown in FIGS. 3 and 4, a mirror  3  is placed in a plane of the opening of a mirror housing  2  made of a synthetic resin. The mirror  3  is angle adjustably mounted to a support frame  4  attachably thereto and detachably therefrom, which is secured to the mirror housing by small screws. A support element  5 , which is elastic and of a plate-like shape, extends integrally from the support frame  4 . On the support element  5  is made a pair of through holes  6 , through which a camera  20  to be described later is supported attachably and detachably with screws  7 .  
         [0040]    On an under portion  2   b  of the mirror housing  2  is made an opening  8 , on inner periphery of which a support projection  9  is integrally formed. With the opening  8  is mated a transparent cover  10  made of a synthetic resin, a ridge  10   a  of which is held by the support projection  9 . Thus, the opening  8  can be closed by the transparent cover  10  approximately flush with the under portion  2   b.    
         [0041]    As shown in FIG. 3, a front portion of the ridge  10   a  of the transparent cover  10 , which lies forward relative to a direction X of vehicular travel, is formed lower stepwise than a corresponding front portion of an edge  8   a  of the opening  8 . On the other hand, a rear portion of the ridge  10   a , which lies backward relative to the direction X of vehicular travel, is formed higher stepwise than a corresponding rear portion of the edge  8   a . Thus, even if there is a gap between the edge  8   a  and the ridge  10   a , the wind is prevented from being caught in the gap when a wind pressure in the opposite direction of vehicular travel exists, and thereby a wind noise is eliminated.  
         [0042]    As shown in FIG. 5, a plurality of threaded holes  11  for the camera  20  are provided at the respective corners of the inner surface of the transparent cover  10 . And a shielding element  12  which has a black colored cylinder-like shape is integrally formed by molding on the inner surface of the transparent cover  10 . The shielding element  12  and the transparent cover  10  surround a lens  23  of a CCD camera  22  to define a closed space S.  
         [0043]    The shielding element  12  prevents not only undesired light from entering the lens  23  of the CCD camera  22  but also dust and water from intruding into the neighborhood of the lens  23  in collaboration with the transparent cover  10 . It improves image clearness and prevents deterioration of a field of view due to unclear images caused by the soiled lens. The shielding element  12  is integrally formed to the transparent cover  10  by molding.  
         [0044]    The camera  20  includes a holder  21  of a rectangular parallelepiped shape and the CCD camera  22  built in the holder  21 . The lens  23  comprising, for example, a wide angle lens or a fish-eye lens sits on an end of the CCD camera  22 . The camera  20  is held in the mirror housing  2  so that the lens  23  faces the opening  8 . A plurality of support elements  24  are provided around the camera  20 . Each of the support elements  24  is inserted through the opening  8  to be in contact with the support projection  9  and interposed between the support projection  9  and the ridge  10   a  of the transparent cover  10  when the opening  8  is closed with the transparent cover  10 .  
         [0045]    At each corner of the holder  21  of the camera  20  is provided a flange  25 . A through hole  26  is provided for a flange  25  and a through hole  26  is aligned with a threaded hole  11  at each corner of the transparent cover  10 . A screw  27  is fastened into a threaded hole  11  through a through hole  26 , thereby enabling mounting of the transparent cover  10  on the camera  20  to integrate a camera module. On a top surface  20   a  of the camera  20  are made a pair of threaded holes  28 , which are aligned with the pair of through holes  6  bored on the support element  5  that is formed integrally on the support frame  4 , when the camera module is temporarily assembled into the mirror housing  2 .  
         [0046]    Steps for mounting the camera  20  in the mirror housing of the door D 1  will be described referring to FIGS. 5 and 6. First as shown in FIG. 5, a threaded hole  11  of the transparent cover  10  is aligned with a through hole  26  of a flange  25 , fastened with a screw  27  and thereby the camera module, camera  20  and transparent cover  10  combined integrally, is assembled. This camera module is subsequently inserted into the mirror housing  2  through the opening  8  from outside. Then the support elements  24  of the camera  20  shown in FIGS. 3 and 4 are supported by the support projection  9  and the ridge  10   a  of the transparent cover  10 . This will complete temporary mounting of the camera module into the mirror housing  2 . The top surface  20   a  of the camera  20  can hold a gap relative to the support element  5 , and a through hole  6  of the support element  5  and a corresponding threaded hole  28  of the camera  20  are aligned.  
         [0047]    As shown in FIG. 3, a screw  7  is inserted through a through hole  6  and fastened into a corresponding threaded hole  28 . Thus, the camera  20  is elastically held in the mirror housing  2  attachably thereto and detachably therefrom utilizing bending elasticity of the support element  5  as shown in FIG. 4 with the two-dot chain line.  
         [0048]    When the camera  20  is fastened to the support element  5  in the mirror housing  2 , a screwdriver (not shown) is brought in through the plane of opening  2   a  of the mirror housing  2  while the mirror  3  is removed.  
         [0049]    In the door mirror  1  described above, the opening  8  can be closed by the transparent cover  10  while the camera  20  is installed in the mirror housing  2 . Also assembling such as mounting or removing of the camera  20  from the mirror housing  2  and positioning of the camera  20  with the opening  8  can be easily performed. It is possible to replace the camera  20  for the mirror housing  2  easily since the camera  20  is supported in the mirror housing  2  attachably thereto and detachably therefrom. In addition, when the mirror housing  2  is damaged, reuse of the camera  20  for a new mirror housing can be permitted by removing it. Since the camera  20  is supported elastically in the mirror housing  2 , it is also possible to prevent so serious damage that spoils the chance of reuse. Further the elastic support absorbs the vibration transmitted to the camera  20  from the mirror housing  2 , thereby eliminating image blur caused by vibration of the camera  20  during vehicular travel.  
         [0050]    Elastic support at the fastening point between the support element  5  and the camera module made up of the camera  20  and the transparent cover  10  is enhanced assisted by the elasticity intrinsic to the support element  5 . In this way, elasticity of the support element  5  is utilized to its best advantage and positioning of the camera module during assembly is rendered much easier.  
         [0051]    When the camera  20  is fastened to the support element  5  with the screws  7 , elasticity produced by bending displacement of the support element  5  itself can be advantageously used for assembling, since there is the gap at the fastening point between the support element  5  and the camera  20 .  
         [0052]    The transparent cover  10  and the shielding element  12  surround the lens  23  of CCD camera  22  to define a closed space, thereby preventing undesired light from entering the lens  23  and improving the quality of acquired images. It also protects against dust and water intruding into the neighborhood of the lens  23 .  
         [0053]    The transparent cover  10  and the shielding element  12  prevent the light entering the opening  8  through the transparent cover  10  from leaking through the gap  3   a  between the mirror  3  and the plane of opening  2   a  of the mirror housing  2 .  
         [0054]    [0054]FIG. 7 shows the camera built-in rearview mirror according to the second embodiment of the present invention. In the second embodiment, a plurality of luminous bodies  30  such as light emitting diodes (LEDs) are provided around the shielding element  12  of the first embodiment and the light emitted by the luminous bodies  30  is directed through the transparent cover  10  to an imaging area taken by the camera  20 . Thus the quality of acquired images is much more improved, especially when the vehicle A is in a launching operation at night.  
         [0055]    If the luminous bodies  30  are integrated with the camera  20  and the transparent cover  10 , mounting of the camera  20  into the mirror housing  2  will complete both installation of the luminous bodies  30  and closing of the opening  8  with the transparent cover  10 . Also positioning of the camera  20  with the opening  8  can be performed easily in parallel with closing of the opening  8  with the transparent cover  10 . Therefore, the assembly of the camera  20 , the transparent cover  10  and the luminous bodies  30  with the mirror housing  2  can be much easily conducted.  
         [0056]    Descriptions have been made for a door mirror mounted on a passenger-seat side in the embodiments described before, but they are applicable to a door mirror mounted on a driver-seat side. While the invention has been described in detail and with reference to the door mirror as an exterior rearview mirror for example, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.