Abstract:
Disclosed herein is a camera device including: a housing having an opening; a lens exposed from the opening of the housing; a lens barrel for holding the lens, the lens barrel being fitted in the housing to expose the lens from the opening of the housing; a packing provided between the lens barrel and the housing for preventing the entry of a water flow passed through the opening; an imaging mechanism having an imaging device for detecting incident light transmitted through the lens; and a buffer portion configured to reduce the pressure of the water flow in a water flow path between the opening and the packing.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority from Japanese Patent Application No. JP 2010-028885 filed in the Japanese Patent Office on Feb. 12, 2010, the entire content of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a camera device, and more particularly to a camera device preferably used as an on-vehicle camera mounted on a vehicle such as an automobile to improve the convenience and safety of the vehicle. 
         [0004]    2. Description of the Related Art 
         [0005]    A camera device mounted on a vehicle body of an automobile to improve the convenience and safety of the automobile is known in the past. In such a camera device, an image detected by the camera device is visually recognized through a monitor device provided near a cockpit. This kind of camera device has a substantially rectangular housing containing an imaging lens and an imaging device. This housing is built in or mounted on a back door, outside rearview mirrors, front spoiler, etc. of the vehicle body so as to expose the imaging lens to the outside of the housing. According to such a camera device, an area around the vehicle that may become a blind spot to a driver can be imaged, thereby improving the safety and convenience of the vehicle. 
         [0006]    This kind of camera device includes a watertight structure provided between the housing and a lens barrel for holding the imaging lens.  FIG. 10  shows an existing camera device  100  including a housing  101  composed of a front case  102  and a rear case  103  joined together, an imaging lens  104 , a lens barrel  105  built in the front case  102  for holding the imaging lens  104 , and an imaging mechanism  108  having an imaging device  107  for detecting incident light transmitted through the imaging lens  104 . 
         [0007]    The front case  102  and the rear case  103  of the housing  101  are joined together by means of screws with a packing  109  interposed therebetween. Accordingly, the entry of water from a joined portion between the front case  102  and the rear case  103  can be prevented by the packing  109 . 
         [0008]    The front case  102  of the housing  101  is formed with an opening  110 , and the lens barrel  105  is fitted in the opening  110  of the front case  102 . Further, a packing  111  is interposed between the front case  102  and the lens barrel  105 . Accordingly, the entry of water from a clearance between the front case  102  and the lens barrel  105  can be prevented by the packing  111 . 
         [0009]    Some of the related art is discussed in Japanese Patent Laid-Open No. 2009-265473. 
       SUMMARY OF THE INVENTION 
       [0010]    In general, the performance required by the watertight structure in an on-vehicle camera such as the camera device  100  is evaluated as a watertight performance in the case that the camera device is immersed in water. Accordingly, unless water enters the camera device immersed in water, the watertight performance satisfies a given standard. However, since the on-vehicle camera is exposed to the outside of the vehicle body, the watertight performance must be maintained also against high-pressure hot water sprayed by a high-pressure car wash, for example. 
         [0011]    In an existing on-vehicle camera capable of supporting high-pressure water, a watertight performance is maintained by using dedicated watertight parts and an adhesive, causing an increase in parts count and cost. 
         [0012]    It is accordingly desirable to provide a camera device which can maintain a watertight performance much higher in level than the existing watertight standard with a simple structure. 
         [0013]    In accordance with the present invention, there is provided a camera device including a housing having an opening; a lens exposed from the opening of the housing; a lens barrel for holding the lens, the lens barrel being fitted in the housing to expose the lens from the opening of the housing; a packing provided between the lens barrel and the housing for preventing the entry of a water flow passed through the opening; an imaging mechanism having an imaging device for detecting incident light transmitted through the lens; and with a buffer portion configured to reduce the pressure of the water flow in a water flow path between the opening and the packing. 
         [0014]    According to an embodiment of the present invention, the water flow that has entered the housing from the opening first strikes the buffer portion before reaching the packing. That is, the water flow does not directly strike the packing. Accordingly, the watertight effect of the packing can be reliably maintained. 
         [0015]    Other features of the invention will be more fully understood from the following detailed description and appended claims when taken with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a side view of an automobile on which a camera device according to a preferred embodiment of the present invention is mounted; 
           [0017]      FIG. 2  is a perspective view of the automobile shown in  FIG. 1 ; 
           [0018]      FIG. 3  is an enlarged perspective view of part of the automobile shown in  FIG. 1 , showing a mount position of the camera device; 
           [0019]      FIG. 4  is a perspective view of the camera device; 
           [0020]      FIG. 5  is an exploded perspective view of the camera device; 
           [0021]      FIG. 6  is a sectional view of the camera device; 
           [0022]      FIG. 7  is a sectional view of a camera device according to another preferred embodiment of the present invention; 
           [0023]      FIG. 8  is a sectional view of a camera device according to still another preferred embodiment of the present invention; 
           [0024]      FIG. 9  is a schematic side view for illustrating a watertight standard; and 
           [0025]      FIG. 10  is a sectional view of a camera device in the related art. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    Preferred embodiments of the present invention will now be described in detail with reference to the drawings. The description will be made in the following order. 
         [0027]    1. Housing 
         [0028]    2. Lens barrel 
         [0029]    3. Buffer portion 
         [0030]    As shown in  FIG. 1 , a camera device  1  according to an embodiment of the present invention is used as a rear monitor provided at the rear portion of the vehicle body of an automobile for monitoring the back side of the vehicle body. As shown in  FIGS. 2 and 3 , the camera device  1  is mounted on a back door  2  at a substantially central position thereof and connected to a navigation system  3  or the like, wherein a monitor is provided on a driver side dashboard or instrument panel and an image on the back side of the vehicle body can be displayed on this monitor. The camera device  1  may be mounted on the frontmost portion of the vehicle body, such as the lower portion of a front grille or a front license plate, thereby monitoring the right and left blind spots on the front side of the vehicle body. Further, the camera device  1  may be mounted on the lower portion of each outside rearview mirror, thereby monitoring the side blind spots on the right and left sides of the vehicle body. 
         [0031]    As shown in  FIGS. 4 to 6 , the camera device  1  includes a substantially rectangular housing  10 , a lens barrel  11  fitted in the housing  10 , an imaging mechanism  15  having an imaging device  14  such as a CCD (charge coupled device) and a CMOS (complementary metal oxide semiconductor) for detecting an image through an imaging lens  12  held by the lens barrel  11 , and a shield case  16  for supporting the imaging mechanism  15  in the housing  10  and functioning as a ground to shield any internal and external electromagnetic waves. 
       &lt;1. Housing&gt; 
       [0032]    The housing  10  is composed of a front case  20  and a rear case  21  joined together. The front case  20  and the rear case  21  are substantially rectangular members formed by molding of engineering plastic. The front case  20  and the rear case  21  are joined together by engaging the mating end portions of the front and rear cases  20  and  21  and then bonding them by ultrasonic welding. 
         [0033]    The front case  20  is composed of a cylindrical portion  23  having a circular opening  22  at a substantially central position and a rectangular portion  24  having an internal structure for engaging the lens barrel  11  and an external structure for engaging the rear case  21 . The circular opening  22  has a diameter slightly larger than the outer diameter of the lens barrel  11 . An engaging shoulder portion  25  for engaging the lens barrel  11  through the shield case  16  is formed at the boundary between the cylindrical portion  23  and the rectangular portion  24 . The lens barrel  11  is inserted into the front case  20  from its rear end until coming into engagement with the engaging shoulder portion  25 . In this condition, the outer circumferential surface of the lens barrel  11  is fitted in the circular opening  22  of the front case  20 . 
         [0034]    The rear case  21  has a substantially rectangular shape adapted to be joined to the rectangular portion  24  of the front case  20 . The rear closed end of the rear case  21  is provided with a connection terminal  26  adapted to be connected to the imaging mechanism  15  and a jack portion  27  for engaging a connector cable  4  (see  FIG. 2 ). 
         [0035]    &lt;2. Lens Barrel&gt; 
         [0036]    The lens barrel  11  has a cylindrical barrel portion in which the imaging lens  12  is built and a platelike portion  31  adapted to be joined to a substrate  44  of the imaging mechanism  15 . The imaging lens  12  is held by the barrel portion  30  at its front end. The barrel portion  30  has an outer circumferential surface  30   a,  and an O ring  34  for preventing the water passed through the circular opening  22  of the front case  20  from further flowing into the housing  10 . More specifically, when the lens barrel  11  is fitted in the front case  20 , the O ring  34  is held between the inner circumferential surface of the cylindrical portion  23  of the front case  20  and the outer circumferential surface  30   a  of the barrel portion  30  of the lens barrel  11 , thereby sealing the annular space between the lens barrel  11  and the front case  20  to prevent the water from flowing toward the rear case  21 . In the camera device  1 , the O ring  34  may be replaced by various kinds of packing having a watertight performance. 
         [0037]    &lt;3. Buffer Portion&gt; 
         [0038]    The outer circumferential surface  30   a  of the barrel portion  30  is formed with a buffer wall  35  at a position on the front side of the O ring  34 . The buffer wall  35  functions to reduce the pressure of a water flow entering the housing  10  through a minute clearance C defined between the inner wall of the circular opening  22  and the outer circumferential surface  30   a  of the barrel portion  30 . As shown in  FIG. 6 , the buffer wall  35  projects from the outer circumferential surface  30   a  of the barrel portion  30  into a water flow path between the inner circumferential surface of the cylindrical portion  23  of the front case  20  and the outer circumferential surface  30   a  of the barrel portion  30 . 
         [0039]    Accordingly, the water flow that has entered the housing  10  through the clearance C first strikes the buffer wall  35  before reaching the O ring  34 . That is, the water flow does not directly strike the O ring  34 . In a high-pressure car wash or the like, hot water is sometimes used to improve a washing effect. However, if such a high-pressure hot water flow directly strikes the O ring  34 , the modulus of elasticity of the O ring  34  may be lowered to cause a problem that the watertight effect of the O ring  34  cannot be maintained. Further, even when an adhesive or the like is used to improve the watertight performance, the direct strike of the high-pressure hot water flow on the adhesive similarly causes a problem that the watertight effect of the adhesive cannot be maintained. 
         [0040]    In contrast, according to this preferred embodiment, the buffer wall  35  is provided in the path of a high-pressure hot water flow, thereby preventing the direct strike of the water flow on the O ring  34 . As a result, the watertight effect of the O ring  34  can be reliably maintained. 
         [0041]    In the camera device  1 , a plurality of buffer walls similar to the buffer wall  35  may be provided to further reduce the pressure of the water flow. Further, in the case that the buffer wall  35  is formed at a position directly above the O ring  34  as viewed in  FIG. 6 , the buffer wall  35  functions also as means for positioning the O ring  34 . 
       Other Preferred Embodiments 
       [0042]      FIG. 7  shows another preferred embodiment of the present invention, wherein a buffer wall  35  is formed on the outer circumferential surface  30   a  of the barrel portion  30  of the lens barrel  11  and a buffer projection  37  is additionally formed on the inner wall of the cylindrical portion  23  of the front case  20 . Accordingly, the buffer projection  37  and the buffer wall  35  respectively project from the inner wall of the cylindrical portion  23  and the outer circumferential surface  30   a  of the barrel portion  30  into the path of a high-pressure hot water flow, so that the water flow first directly strikes the buffer projection  37  and next strikes the buffer wall  35 . Accordingly, the pressure of the water flow can be reduced more reliably. 
         [0043]      FIG. 8  shows still another preferred embodiment of the present invention, wherein a conical surface  38  is formed on the outer circumferential surface  30   a  of the barrel portion  30  so as to gradually increase in diameter toward the rear end of the lens barrel  11  as approaching the inner wall of the cylindrical portion  23  of the front case  20 . By forming the conical surface  38 , the pressure of the water flow can be reduced and the direct strike of the water flow on the O ring  34  can be reliably prevented. 
         [0044]    As shown in  FIG. 5 , the platelike portion  31  has a rectangular shape, and the barrel portion  30  is formed at the center on one surface of the platelike portion  31  on the front side of the camera device  1 . On the other hand, a pair of connection blocks  39  project from the other surface of the platelike portion  31  on the rear side of the camera device  1 . The connection blocks  39  are connected to the substrate  44  of the imaging mechanism  15 . The rear end surface (lower end surface as viewed in  FIG. 6 ) of each connection block  39  opposed to the substrate  44  is formed with a groove to be filled with an adhesive  40 , so that the substrate  44  and the platelike portion  31  are bonded together by the adhesive  40 . As shown in  FIG. 5 , each side edge of the platelike portion  31  is formed with an engagement recess  42  to be engaged with the shield case  16 . 
         [0045]    [Imaging Mechanism  15 ] 
         [0046]    The imaging mechanism  15  connected to the connection blocks  39  will now be described. As shown in  FIGS. 5 and 6 , the imaging mechanism  15  has the imaging device  14  for detecting incident light transmitted through the imaging lens  12 , the substrate  44  for mounting the imaging device  14  and forming various circuits, and a circuit chip  45  for processing an image detected by the imaging device  14 . The imaging device  14  may be provided by a CCD or a CMOS, for example. The substrate  44  is a rigid substrate having a substantially rectangular shape. The imaging device  14  is mounted on the front surface of the substrate  44 , and the circuit chip  45  is formed on the back surface of the substrate  44 . Further, a terminal portion (not shown) to be connected to a connector connected to a harness having signal and power cables is also formed on the back surface of the substrate  44 . The substrate is bonded to the connection blocks  39  by the adhesive  40  applied to the front surface of the substrate  44  along its opposite side edges in the condition where the imaging device  14  is opposed to the imaging lens  12  provided at the front end of the lens barrel  11  and focusing of the imaging lens  12  is carried out. 
         [0047]    More specifically, a pair of adhesive applying areas for the adhesive  40  are provided on the front surface of the substrate  44  along its opposite side edges so as to correspond to the pair of connection blocks  39  projecting from the back surface of the platelike portion  31  of the lens barrel  11 . These adhesive applying areas are provided along the opposite side edges of the substrate  44  where parts cannot be mounted. Accordingly, the adhesive applying areas can be provided by effectively utilizing a limited space as ensuring a mounting area for the imaging device  14  and other electronic parts and a forming area for circuit patterns. Thus, a size enlargement of the substrate  44  can be suppressed. 
         [0048]    The adhesive  40  applied to the adhesive applying areas is provided by an ultraviolet curing adhesive or a thermosetting adhesive, for example. After applying the adhesive  40  to the adhesive applying areas of the substrate  44 , the substrate  44  is mounted on the rear surface (lower surface as viewed in  FIG. 6 ) of each connection block  39  having a groove to be filled with the adhesive  40 . After performing the alignment of the imaging lens  12  mounted on the lens barrel  11  and the imaging device  14  mounted on the substrate  44  and also performing the focusing of the imaging lens  12 , the adhesive  40  is cured by applying ultraviolet radiation, for example, to thereby fix the substrate  44  to the connection blocks  39 . 
         [0049]    Thereafter, the unit of the substrate  44  and the lens barrel  11  is connected to the shield case  16 , and the shield case  16  is fitted into the rear case  21 . Thereafter, the lens barrel  11  is fitted into the front case  20  from its rear end. Finally, the front case  20  and the rear case  21  are joined together by ultrasonic welding to thereby manufacture the camera device  1 . In this camera device  1 , the front case and the rear case  21  are joined together by ultrasonic welding. Accordingly, a watertight effect can be obtained at such a joined portion between the front case  20  and the rear case  21  without the need for any special configuration. As a modification, the front case  20  and the rear case  21  may be bonded together by an adhesive. 
         [0050]    In this manner, the lens barrel  11  and the imaging mechanism  15  are preliminarily assembled as a unit, and this unit is built into the housing  10  in manufacturing the camera device  1 . Accordingly, the unit of the lens barrel  11  and the imaging mechanism  15  may be applied also to another housing different in outer diameter from the housing  10 . For example, the unit of the lens barrel  11  and the imaging mechanism  15  is commonly applicable to various housings fit for various vehicles having different external designs. 
         [0051]    As described above, the lens barrel  11  and the imaging mechanism  15  are preliminarily assembled as a unit. Accordingly, although a space is formed between the opening  22  and the O ring  34  and high-pressure hot water may enter this space through the opening  22 , the flow of this hot water does not directly strike the O ring  34  because a buffer portion such as the buffer wall  35 , the buffer projection  37 , and the conical surface  38  is formed in the path of the water flow as shown in  FIGS. 6 to 8 . As a result, the watertight performance of the O ring  34  can be maintained. 
         [0052]    In manufacturing the camera device  1 , the front case and the rear case  21  are joined together by ultrasonic welding. Accordingly, in joining the front case  20  and the rear case  21 , vibration is transmitted to the unit of the lens barrel  11  and the imaging mechanism  15 . To prevent the misalignment between the imaging lens  12  and the imaging device  14  due to vibration or the damage due to friction, the minute clearance C is intentionally defined between the inner wall of the opening  22  of the front case  20  and the outer circumferential surface  30   a  of the barrel portion  30  of the lens barrel  11  (see  FIG. 6 ). Accordingly, there is a possibility that the high-pressure hot water from a high-pressure car wash may enter the camera device  1  from this minute clearance C. However, the camera device  1  includes the O ring  34  provided between the lens barrel  11  and the front case  20  and the buffer portion such as the buffer wall  35 , the buffer projection  37 , and the conical surface  38  provided in the path of the high-pressure hot water flow. With this arrangement, the high-pressure hot water flow does not directly strike the O ring  34  owing to the formation of the buffer portion, so that the watertight performance of the O ring  34  can be maintained. 
         [0053]    Further, according to the camera device  1 , the pressure of the high-pressure hot water flow can be reduced by simply forming the buffer portion such as the buffer wall  35 , the buffer projection  37 , and the conical surface  38  on the lens barrel  11  or the front case  20 . Accordingly, the watertight performance can be improved by a simple configuration without increasing the number of parts and the number of manufacturing steps. 
         [0054]    Further, the camera device  1  can maintain the watertight performance even when it is subjected to the spray of a high-pressure hot water flow as defined by IP69K standard, for example. The IP69K standard is a protective regulation against high-pressure hot water as defined by German Standard DIN40050PART9. More specifically, as shown in  FIG. 9 , hot water having a temperature of 80° C. is sprayed from a nozzle having a specified shape toward a sample under a pressure of 80 to 100 BAR at a rate of 14 to 16 liters/min. The distance between the sample and the nozzle is set to 10 to 15 cm, and the spray angle is set to 0, 30, 60, and 90 degrees with respect to a horizontal direction. At each spray angle, the sample is rotated for 30 seconds in a horizontal plane. The camera device  1  having the above-mentioned configuration can satisfy this IP69K standard. 
         [0055]    While the camera device  1  is used as a on-vehicle camera in the above preferred embodiments, the camera device of the present invention is applicable also to a security camera and an intercom camera, for example. Also in this case, the camera device can be widely used in various installation conditions owing to the configuration that the buffer portion such as the buffer wall  35 , the buffer projection  37 , and the conical surface  38  is formed in the water flow path present in the space between the opening  22  of the front case  20  and the lens barrel  11 , thereby preventing the direct strike of the water flow on the O ring  34 . 
         [0056]    It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factor in so far as they are within the scope of the appended claims or the equivalents thereof.