Abstract:
The electric connector includes a housing having an opening and a bottom, the housing being formed at the bottom with a recess, at least one electric terminal projecting through a bottom of the recess into the housing, and a sealant layer composed of cured light-curing resin, the sealant layer at least partially filling the recess therewith.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to an electric connector including a housing composed of an electrically insulating material, and a plurality of electric terminals composed of an electrically conductive material and housed in the housing. 
         [0003]    2. Description of the Related Art 
         [0004]      FIGS. 1 and 2  illustrate a conventional electric connector  70 . The electric connector  70  includes a box-shaped housing  71  composed of an electrically insulating material, and a plurality of electric terminals  72  composed of an electrically conductive material. In order to prevent moisture from penetrating a gap formed between the housing  71  and the electric terminals  72 , ultraviolet-curing resin  74  is filled entirely over a bottom  73  of the housing  71 . 
         [0005]    For instance, Japanese Patent Application Publication No. 2002-305065 has suggested a water-proof connector including rubber-like elastic material sealing a gap formed between wires connected to connector terminals, and holes through which the connector terminals are inserted, formed through a housing. 
         [0006]    In the conventional electric connector  70  illustrated in  FIGS. 1 and 2 , since the ultraviolet-curing resin  74  used for fixing the electric terminals  72  is filled in the housing  71  so as to entirely cover the bottom  73  of the housing  71  therewith, it is necessary to prepare a lot of the ultraviolet-curing resin  74  in manufacturing the electric connector  70 . 
         [0007]    When ultraviolet rays are irradiated to the ultraviolet-curing resin  74  filled on the bottom  73  during the steps of manufacturing the electric connector  70 , it is difficult for the ultraviolet rays to reach at a periphery of the bottom  73 , that is, a boundary between the bottom  73  and a sidewall  75  of the housing  71 , resulting in that the ultraviolet-curing resin  74  existing around the boundary is insufficiently cured. 
         [0008]    In order to prevent the ultraviolet-curing resin  74  from being insufficiently cured, it is necessary for the ultraviolet-curing resin  74  to absorb ultraviolet rays in an increased amount. Accordingly, it is necessary to prepare a high-powered ultraviolet ray lamp, and it is also necessary for the lamp to irradiate ultraviolet rays in a long period of time, resulting in deterioration in a yield of manufacturing the electric connector  70 . 
         [0009]    In the water-proof connector suggested in the above-mentioned Publication, since the rubber-like elastic material, which corresponds to the ultraviolet-curing resin  74  in the electric connector  70 , is filled in a gap formed between the wire connected to the connector terminal, and the through-hole through which the connector terminal is inserted and which is formed through the housing, a relatively small amount of the rubber-like elastic material is used. However, fluidic rubber has to be filled into each of the connector terminals through a dispenser with the result of complexity in manufacturing steps. 
       SUMMARY OF THE INVENTION 
       [0010]    In view of the above-mentioned problems in the conventional electric connector, it is an object of the present invention to provide an electric connector which is capable of waterproofing a gap formed between an electric terminal and a housing, and reducing an amount of light-curing resin used for fixing electric terminals, without both complexity in steps of manufacturing an electric connector and reduction in a yield of manufacturing an electric connector. 
         [0011]    It is further an object of the present invention to provide a housing suitable to such an electric connector. 
         [0012]    In one aspect of the present invention, there is provided an electric connector including a housing having an opening and a bottom, the housing being formed at the bottom with a recess, at least one electric terminal projecting through a bottom of the recess into the housing, and a sealant layer composed of cured light-curing resin, the sealant layer at least partially filling the recess therewith. 
         [0013]    The electric connector in accordance with the present invention is able to waterproof gaps formed between the housing and the electric terminals by curing light-curing resin filled in the recess, and further, reduce an amount of resin used for fixing the electric terminals, relative to a case in which light-curing resin is filled entirely on a bottom of the housing. Furthermore, since it is not necessary to change a step of filling light-curing resin, there is not brought complexity in steps of manufacturing the electric connector. In addition, since light-curing resin is not filled on a periphery of a bottom of the housing, at which it is difficult for lights for curing the light-curing resin to reach, it is no longer necessary to prepare a high-powered ultraviolet ray lamp, and it is also no longer necessary for the lamp to irradiate ultraviolet rays in a long period of time, avoiding deterioration in a yield of manufacturing the electric connector. 
         [0014]    It is preferable that the recess, when vertically viewed, has a periphery defined by a continuous curve in a closed shape or a combination of a curve and a straight line. 
         [0015]    By designing the recess to have such a periphery as mentioned above, when light-curing resin is filled in the recess in the steps of manufacturing the electric connector, it is possible to adequately fill light-curing resin around a periphery of the recess, and hence, possible to fill light - curing resin in the recess without gaps, ensuring enhancement in an adhesive force between the light-curing resin and the housing. 
         [0016]    For instance, the periphery may be designed to be a rectangle with rounded corners. 
         [0017]    For instance, the periphery may be designed to be substantially H-shaped. 
         [0018]    It is preferable that the recess has an inclining sidewall. 
         [0019]    By designing the recess to have an inclining sidewall, when light-curing resin is filled in the recess in the steps of manufacturing the electric connector, the inclining sidewall makes the light-curing resin have a gradually reducing thickness towards a periphery of the recess from a bottom of the recess. 
         [0020]    Accordingly, when lights are irradiated onto the light-curing resin for curing the light-curing resin, the lights can surely each at the light-curing resin existing around a periphery of the recess, ensuring that a reaction rate at which the light-curing resin is cured can be increased, and further, it is possible to enhance an adhesive force between the light-curing resin and the housing. 
         [0021]    It is preferable that the inclining sidewall has a flat surface. 
         [0022]    It is preferable that at least a part of the inclining sidewall is a projecting curved surface. 
         [0023]    By designing at least a part of the inclining sidewall to be a projecting curved surface, it is possible to reduce a volume of the recess in comparison with a case in which the inclining the sidewall has a flat surface, and hence, possible to reduce an amount of the light-curing resin used for filling the recess, and further, it is also possible to increase an area in which the inclining sidewall of the recess makes contact with the light-curing resin in comparison with a case in which the inclining the sidewall has a flat surface, and hence, possible to enhance an adhesive force between the light-curing resin and the housing. Furthermore, it is possible to increase a rate at which a thickness of the light-curing resin filled in the recess is reduced towards a periphery of the recess from a bottom of the recess, ensuring enhancement an adhesive force between the light-curing resin and the housing. 
         [0024]    It is preferable that at least a part of the inclining sidewall is continuously raised and recessed. 
         [0025]    By designing at least a part of the inclining sidewall to be continuously raised and recessed, similarly to the above-mentioned case, it is possible to reduce a volume of the recess in comparison with a case in which the inclining the sidewall has a flat surface, and hence, possible to reduce an amount of the light-curing resin used for filling the recess, and further, it is also possible to increase an area in which the inclining sidewall of the recess makes contact with the light-curing resin in comparison with a case in which the inclining the sidewall has a flat surface, and hence, possible to enhance an adhesive force between the light-curing resin and the housing. As an example of the inclining sidewall designed to be continuously raised and recessed, the inclining sidewall may be designed to be step-shaped. 
         [0026]    It is preferable that each of steps has an inclining sidewall. 
         [0027]    It is preferable that the recess has an area smaller than an area of the bottom of the housing when viewed vertically. 
         [0028]    In another aspect of the present invention, there is provided a housing defining a part of an electric connector, the housing having an opening and a bottom and being formed at the bottom with a recess, the recess being formed at a bottom thereof with at least one through-hole through which an electric terminal is inserted such that the electric terminal projects into the housing, the recess being to be at least partially filled with cured light-curing resin. 
         [0029]    The advantages obtained by the above-mentioned present invention will be described hereinbelow. 
         [0030]    The electric connector in accordance with the present invention is able to cause gaps formed between electric terminals and a housing to be kept waterproof, and further, reduce an amount of light-curing resin to be filled in a recess for fixing the electric terminals, without complexity in steps of manufacturing the electric connector, and further without a fabrication yield of the electric connector. 
         [0031]    The above and other objects and advantageous features of the present invention will be made apparent from the following description made with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1  is a plan view of a conventional electric connector. 
           [0033]      FIG. 2  is a cross-sectional view taken along the line D-D in  FIG. 1 . 
           [0034]      FIG. 3  is a plan view of the electric connector in accordance with the first embodiment of the present invention. 
           [0035]      FIG. 4  is a cross-sectional view taken along the line A-A in  FIG. 3 . 
           [0036]      FIG. 5  is a table showing a relation between a reaction rate of light-curing resin in dependence on a total amount of a light irradiated thereto, and a depth of the light-curing resin. 
           [0037]      FIG. 6  is a plan view of the electric connector in accordance with the second embodiment of the present invention. 
           [0038]      FIG. 7  is a cross-sectional view taken along the line B-B in  FIG. 4 . 
           [0039]      FIG. 8  is a plan view of the electric connector in accordance with the third embodiment of the present invention. 
           [0040]      FIG. 9  is a cross-sectional view taken along the line C-C in  FIG. 8 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
       [0041]    The electric connector  100  in accordance with the first embodiment of the present invention is explained hereinbelow with reference to  FIGS. 3 to 5 . 
         [0042]    As illustrated in  FIGS. 3 and 4 , the electric connector  100  includes a housing  10 , a plurality of electric terminals  13 , and a sealant layer  17 . 
         [0043]    The housing  10  has a substantially rectangular bottom  15 , and a sidewall  19  vertically standing at a periphery of the bottom  15 . An upper edge of the sidewall  19  defines an opening  11 . 
         [0044]    The housing  10  is formed at the bottom  15  with a recess  16 . The recess  16  has an inclining sidewall  18 , and hence, the recess  16  has a reverse-trapezoidal cross-section. The inclining sidewall  18  has a flat surface, and defines a depth of the recess  16  gradually reducing towards the sidewall  19  of the housing  10  from a bottom  16   b  of the recess  16 . 
         [0045]    The recess  16  has a smaller area than an area of the bottom  15  of the housing  10  when viewed vertically, as illustrated in  FIG. 3 . Accordingly, the bottom  15  of the housing  10  can be seen as a frame-shaped shelf only between a peripheral edge  16   a  of the recess  16  and the sidewall  19  of the housing  10 . 
         [0046]    The recess  16  is formed at the bottom  16   b  thereof with a plurality of through-holes through which the electric terminals  13  are inserted. Each of the through-holes pass through a bottom portion  12  of the housing  10 , and has an elongated rectangular cross-section in line with a horizontal cross-section of the electric terminals  13 . 
         [0047]    Each of the electric terminals  13  is inserted into the through-hole such that a distal end  13   a  thereof projects beyond the bottom  15  of the housing  10  into an inner space  14  defined in the housing  10 . 
         [0048]    The sealant layer  17  is composed of light-curing resin filled in the recess  16 . The sealant layer  17  seals the electric terminals  13  from the surroundings, that is, waterproofs gaps formed between the electric terminals  13  and the through-holes at the bottom of the recess  16 . 
         [0049]    As illustrated in  FIG. 3 , the peripheral edge  16   a  of the recess  16  is designed to have a closed shape defined by a combination of curves and straight lines, when viewed vertically. Specifically, the peripheral edge  16   a  is rectangular in shape with rounded corners. 
         [0050]    In the steps of manufacturing the electric connector  100 , the light-curing resin can be filled in the recess  16  by dispensing the light-curing resin into the recess  16  only once through the use of a dispenser (not illustrated), and hence, it is not necessary to change a conventional step of filling the recess with the light-curing resin, resulting in bringing no complexity in the manufacturing steps. Furthermore, since the light-curing resin is not filled at a peripheral edge  15   a  of the bottom  15  of the housing  10  at which ultraviolet rays for curing the light-curing resin are difficult to reach, it is not necessary to prepare a high-power ultraviolet ray lump, and to irradiate ultraviolet rays onto the light-curing resin for a long time, with the result of no reduction in a yield of fabricating the electric connector  100 . 
         [0051]    In addition, since the peripheral edge  16   a  of the recess  16  is designed to have a shape defined by a combination of curves and straight lines, when viewed vertically, when the light-curing resin is filled in the recess  16  in the steps of manufacturing the electric connector  100 , it is possible to adequately fill the light-curing resin around the peripheral edge  16   a  of the recess  16 , and hence, possible to fill the light-curing resin in the recess  16  without gaps, ensuring enhancement in an adhesive force between the light-curing resin and the housing  10 . 
         [0052]    The sealant layer  17  in the first embodiment is designed to have a thickness (depth) from the bottom  16   b  of the recess  16  to the upper edge  16   a  of the inclining sidewall  18 . It should be noted that the sealant layer  17  may be designed to have a thickness smaller than a height of the inclining sidewall  18 , if the sealant layer  17  can sufficiently seal the electric terminals  13  from the surroundings, and a sufficient adhesive force can be given between the sealant layer  17  and the recess  16 , in which case, an amount of the light-curing resin to be filled in the recess  16  can be reduced in comparison with a case in which the recess  16  is entirely filled with the light-curing resin. 
         [0053]    In the first embodiment, the sealant layer  17  filled in the recess  16  is designed to have a thickness of about 3 mm at a center thereof. 
         [0054]    As the light-curing resin to be filled in the recess  16 , there may be used a resin which can be cured by a curing-light, for instance, a visible light or an invisible light such as a ultraviolet ray and an infra-red ray. In the first embodiment, there is used a resin which is cured when ultraviolet rays are irradiated thereto, as mentioned earlier. 
         [0055]    Hereinbelow is explained a relation between a reaction rate of the light-curing resin in dependence on a total amount of a curing-light irradiated thereto, and a depth of the light-curing resin, with reference to  FIG. 5 . 
         [0056]    The table shown in  FIG. 5  indicates the reaction taken by the three light-curing resins each having a thickness of 1 mm, 2 mm and 3 mm when cured by curing-lights irradiated from a high pressure mercury lamp. The reaction was measured by a Fourier transform infrared spectrophotometer (FTIS). 
         [0057]    As shown in  FIG. 5 , there was obtained a reaction rate of 100% to a depth of 1 mm when a total amount of curing-lights was 15,000 mJ/cm 2 . Similarly, there were obtained reaction rates of 95% and 90% to depths of 2 mm and 3 mm, respectively, when a total amount of curing-lights was 15,000 mJ/cm 2 . 
         [0058]    When a total amount of curing-lights was 10,000 mJ/cm 2 , there were obtained reaction rates of 92%, 82% and 70% to depths of 1 mm, 2 mm and 3 mm, respectively. 
         [0059]    When a total amount of curing-lights was 5,000 mJ/cm 2 , there were obtained reaction rates of 62%, 50% and 40% to depths of 1 mm, 2 mm and 3 mm, respectively. 
         [0060]    In light of the above-mentioned measurement results, it is understood that light-curing resin having a smaller depth can be cured in a shorter period of time on the assumption that the same total amount of curing-lights is irradiated to light-curing resins. 
         [0061]    Since the inclining sidewall  18  of the recess  16  upwardly inclines towards the sidewall  19  of the housing  10  from a center of the recess  16 , a depth of the recess  16  gradually decreases towards the peripheral edge  16   a  of the recess  16  from the bottom  16   b  of the recess  16 . Thus, a thickness of the light-curing resin filled in the recess  16  gradually decreases towards the peripheral edge  16   a.  As a result, a curing-light can reach the recess  16  by a shorter distance at a location closer to the peripheral edge  16   a  of the recess  16 . Accordingly, since the light-curing resin of which the sealant layer  17  is composed can be surely cured even at a location close to the peripheral edge  16   a  of the recess  16 , it is possible to enhance an adhesive force acting between the light-curing resin and the housing  10 . 
       Second Embodiment 
       [0062]    The electric connector  200  in accordance with the second embodiment of the present invention is explained hereinbelow with reference to  FIGS. 6 and 7 . Parts or elements that correspond to those of the electric connector  100  illustrated in  FIGS. 3 and 4  have been provided with the same reference numerals, and will not be explained. 
         [0063]    As illustrated in  FIGS. 6 and 7 , the peripheral edge  26   a  of the recess  26  in the second embodiment is designed to have a shape defined by a combination of curves and straight lines. Specifically, a part of the peripheral edge  26   a  is inwardly recessed such that the recess  26  is substantially H-shaped, when viewed vertically. By designing the recess  26  to have the above-mentioned shape, it is possible for the recess  26  to have a volume smaller than a volume of the recess  16  illustrated in  FIG. 3 , and hence, it is possible to reduce an amount of light-curing resin to be filled in the recess  26 . 
         [0064]    As illustrated in  FIG. 7 , the recess  26  in the electric connector  200  is designed to have a step-shaped inclining sidewall  28 . Since the recess  26  including a step-shaped inclining sidewall  28  can have a smaller volume than a volume of the recess  16  including the inclining sidewall  18  having a flat surface, illustrated in  FIG. 4 , it is possible to reduce an amount of light-curing resin to be filled in the recess  26 . 
         [0065]    In addition, since a reaction rate at which light-curing resin filled on the step-shaped inclining sidewall  28  is cured can be enhanced, it is possible to increase an adhesive force between the light-curing resin and the housing  20 . Furthermore, the step-shaped inclining sidewall  28  increases an area at which the light-curing resin makes contact with the recess  26  in comparison with the inclining sidewall  18  having a flat surface (see  FIG. 4 ), ensuring that an adhesive force between the light-curing resin and the recess  26  can be enhanced. The step-shaped inclining sidewall  28  has a thickness (a depth) starting from a bottom of the recess  26  and terminating at a bottom  25  of the housing  20 , that is, an upper edge of the recess  26 . Part and functions thereof other than the above-mentioned ones are identical with those of the electric connector  100  in accordance with the first embodiment, illustrated in  FIGS. 3 and 4 . 
       Third Embodiment 
       [0066]    The electric connector  300  in accordance with the third embodiment of the present invention is explained hereinbelow with reference to  FIGS. 8 and 9 . Parts or elements that correspond to those of the electric connector  100  illustrated in  FIGS. 3 and 4  have been provided with the same reference numerals, and will not be explained. 
         [0067]    As illustrated in  FIGS. 8 and 9 , the recess  36  formed at a bottom  35  of a housing  30  is designed to have a peripheral edge  36   a  defined by a combination of curves and straight lines, when viewed vertically. Specifically, a part of the peripheral edge  36   a  is inwardly recessed such that the recess  36  is substantially H-shaped, when viewed vertically. By designing the recess  36  to have the above-mentioned shape, it is possible for the recess  36  to have a volume smaller than a volume of the recess  16  illustrated in  FIG. 3 , and hence, it is possible to reduce an amount of light-curing resin to be filled in the recess  36 . 
         [0068]    As illustrated in  FIG. 9 , the recess  36  in the electric connector  300  is designed to have an inclining sidewall  38  having a projecting curved surface. Since the recess  36  including the inclining sidewall  38  having a projecting curved surface can have a smaller volume than a volume of the recess  16  including the inclining sidewall  18  having a flat surface, illustrated in  FIG. 4 , it is possible to reduce an amount of light-curing resin to be filled in the recess  36 . 
         [0069]    In addition, a thickness of the light-curing resin existing on the inclining sidewall  38  is made smaller at a location closer to a peripheral edge  36   a  of the recess  36 , and hence, a reaction rate at which the light-curing resin filled on the inclining sidewall  38  is cured is enhanced. Thus, an adhesive force between the light-curing resin and the housing  30  can be kept stable, even if an amount of lights irradiated to the light-curing resin were reduced to some degree. Furthermore, the inclining sidewall  38  having a projecting curved surface increases an area at which the light-curing resin makes contact with the recess  36  in comparison with the inclining sidewall  18  having a flat surface (see  FIG. 4 ), ensuring that an adhesive force between the light-curing resin and the recess  36  can be enhanced. The inclining sidewall  38  has a thickness (a depth) starting from a bottom of the recess  36  and terminating at a bottom  35  of the housing  30 , that is, an upper edge of the recess  36 . 
         [0070]    Part and functions thereof other than the above-mentioned ones are identical with those of the electric connector  100  in accordance with the first embodiment, illustrated in  FIGS. 3 and 4 . 
         [0071]    The above-mentioned electric connectors  100 ,  200  and  300  are just exemplary embodiments of the present invention, and thus, the electric connector in accordance with the present invention is not to be limited to the electric connectors  100 ,  200  and  300 . 
       INDUSTRIAL APPLICABILITY 
       [0072]    The electric connector in accordance with the present invention can be used in fields of automobile industry and electronic/electric device industry, as a part of electronic and electric devices or as a part of electric wires to be equipped in an automobile. 
         [0073]    While the present invention has been described in connection with certain preferred embodiments, it is to be understood that the subject matter encompassed by way of the present invention is not to be limited to those specific embodiments. On the contrary, it is intended for the subject matter of the invention to include all alternatives, modifications and equivalents as can be included within the spirit and scope of the following claims. 
         [0074]    The entire disclosure of Japanese Patent Application No. 2011-269331 filed on Dec. 8, 2011 including specification, claims, drawings and summary is incorporated herein by reference in its entirety.