Abstract:
An electrical connector to be connected to a mating connector includes a housing formed of an insulation material; and a terminal disposed in the housing. The terminal is formed in a curved shape bent in a thickness direction thereof. The terminal includes a held portion fixed to the housing, an elastic arm portion, and a connection portion to be connected to a circuit board. The elastic arm portion includes a contact portion and a slant surface portion. The slant surface portion has a thickness decreasing toward a distal end portion of the elastic arm portion, and the contact portion is disposed adjacent to the slant surface portion.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
     The present invention relates to an electrical connector including a terminal. The terminal is formed by bending a metal strip in a thickness direction thereof. 
     A conventional electrical connector (a connector) is disclosed in Patent Reference. In the conventional electrical connector disclosed in Patent Reference, a terminal of the connector has a shape of an approximate S-shape combining a U-shape portion with an upside-down U-shape portion. The upside-down U-shape portion or a held portion of the terminal is disposed from an upper direction in a circumferential wall of a housing. The U-shape portion of the terminal includes a contact portion for contacting with a mating terminal of a mating connector.
     Patent Reference: Japanese Patent Publication No. 2007-035291   

     In the conventional electrical connector disclosed in Patent Reference, the housing includes a central wall rising from a bottom wall thereof in a region surrounding by the circumferential wall. The central wall includes a terminal holding groove. The U-shape portion of the terminal is situated along an inner surface of the housing, in other words, from an inner surface of the circumferential wall to a surface of the central wall, through the bottom wall. The U-shape portion has elasticity. 
     In particular, an elastic arm portion is provided in a portion rising along the surface of the central wall. Most part of the elastic arm portion is situated in the terminal holding groove. The elastic arm portion includes a contact portion at a distal end portion thereof. The contact portion protrudes toward the held portion. The contact portion is formed by bending the distal end portion into an angular shape so that an apex portion of the angular shape is situated outside the terminal holding groove. 
     When the conventional connector is connected to the mating connector from the upper direction, the apex portion of the contact portion is pressed by the mating terminal, thereby the elastic arm portion is displaced elastically in a direction perpendicular to a direction the connectors are connected (a connecting direction). Accordingly, the contact portion contacts with the mating terminal with a certain contact pressure. 
     The conventional connector disclosed in Patent Reference is soldered to a circuit board so that the bottom wall thereof is placed on the circuit board. Electronic components including the connector are loaded on an electrical device in a state of being mounted on the circuit board. Therefore, it is demanding to lower a height of the electronic component. Accordingly, the connector needs to have a low height in the connecting direction. Therefore, it is important to shorten the elastic arm portion while maintaining the contact pressure at the contact portion, since the terminal governs the height of the connector most effectively. 
     In the conventional connector disclosed in Patent Reference, the terminal has a certain height, in other words, the elastic arm portion has a certain length from a lower end portion thereof to the contact portion thereof necessary to be displaced elastically by a certain amount in order to maintain the contact pressure at the contact portion. Further, the contact portion is bent into the angular shape so that the apex portion thereof contacts with the mating terminal. 
     Therefore, a portion situated upper side of the apex portion functions only for guiding the mating connector, without contribution to contacting with the mating connector, the elastic displacement. Moreover, the portion situated upper side of the apex portion extends an entire length of the elastic arm portion. 
     On the other hand, it becomes difficult to guide the mating terminal successfully when the portion situated upper side of the apex portion is eliminated. When the contact portion lowers a position thereof as maintaining the angular shape thereof, the elastic arm portion shortens the length thereof, resulting in the lower elasticity. The thinner the terminal is made in order to obtain the sufficient elasticity, the weaker the contact pressure becomes. 
     In view of the problems described above, an object of the present invention is to provide an electrical connector including a terminal enabling a height of the connector to be lowered, by shortening a height of an elastic arm portion thereof while maintaining an adequate length of the elastic displacement arm portion and a contact pressure. 
     Further objects and advantages of the invention will be apparent from the following description of the invention. 
     SUMMARY OF THE INVENTION 
     In order to attain the objects described above, according to an aspect of the present invention, an electrical connector (a connector) includes a housing made of an electrical insulating material and a terminal made by bending a metal strip and disposed in the housing. The terminal includes a held portion for being held in the housing, an elastic arm portion and a connecting portion. The elastic arm portion extends from the held portion. The elastic arm portion includes a contact portion at a distal end portion thereof. The elastic arm portion is displaced elastically when the contact portion is pressed by a mating terminal of a mating connector. The connecting portion extends from another end of the held portion to be connected to a circuit board. 
     In the connector according to the aspect of the present invention, when the connector is connected to the mating connector, the elastic arm portion is displaced elastically at least in a direction perpendicular to a direction that the connector is connected to the mating connector or a connecting direction when the contact portion is pressed by interfering with the mating connector. 
     In the connector according to the aspect of the present invention, the elastic arm portion is inclined in a direction for contacting with the mating connector as extending to the distal end portion thereof. Further, the elastic arm portion includes a tapered portion formed by reducing a thickness thereof as being closer to the distal end portion thereof. The contact portion is provided as a boundary zone between the tapered portion and a portion situated next to the tapered portion of the elastic arm portion. 
     In the connector according to the aspect of the present invention described above, the tapered portion is situated close to the distal end portion of the elastic arm portion. Therefore, the contact portion is situated close to the distal end portion since the contact portion is composed of the boundary zone between the tapered portion and the portion situated next thereto. 
     When the connector is connected to the mating connector, the mating terminal enters in the connecting direction as contacting slidingly with the tapered portion which guides the mating terminal. The contact portion faces toward the direction perpendicular to the connecting direction since the contact portion is formed as the boundary zone between the tapered portion and the portion situated next thereto. Therefore, the mating terminal interferes with the contact portion, thereby pressing and elastically displacing the contact portion. As a result, the mating terminal contacts with the contact portion with a certain contact pressure as the connector is connected to the mating connector completely. 
     In the connector according to the aspect of the present invention, it is adequate that the tapered portion is formed in a short region close to an edge of the distal end portion of the elastic arm portion. Therefore, it is possible that the elastic arm portion has a certain length necessary to obtain a sufficient elasticity and the contact pressure against the mating terminal without thinning the thickness thereof. The elastic arm portion thus configured is capable of guiding the mating terminal as well. 
     In the connector according to the aspect of the present invention, it is preferable that the tapered portion of the elastic arm portion has a rounded shape at an edge portion thereof. Upon being connected to the mating connector, either of the mating terminal or the terminal having the tapered portion thus shaped is not damaged caused by an impact due to a slight misplacement of the mating connector in the direction perpendicular to the connecting direction. 
     In the connector according to the aspect of the present invention, it is preferable that the elastic arm portion is partially situated in the terminal holding groove of the housing and the contact portion thereof is situated outside the terminal holding groove. It is adequate that only the contact portion of the elastic arm portion is situated outside the terminal holding grove. 
     Therefore, the elastic arm portion is capable of displacing elastically in the terminal holding groove as the contact portion contacts with the mating terminal. As a result, the elastic arm portion is not damaged by receiving an unfavorable force from the mating terminal. Further, the elastic arm portions next to each other do not contact with each other inadvertently. 
     As described above, the connector according to the present invention is not similar to the conventional terminal since the terminal thereof made from the metal strip including the contact portion which is not an apex portion formed by bending the metal strip in the thickness direction thereof. 
     In the aspect of the present invention, the elastic arm portion has the tapered portion formed by crushing so as to reduce the thickness thereof as being closer to the distal end portion thereof. Therefore, the boundary zone between the tapered portion and the portion of the elastic arm portion which is not crushed has a protruding shape. The contact portion is provided as the boundary zone thus shaped. 
     In the aspect of the present invention, the contact portion is formed in a short region at the distal end portion thereof. Therefore, the elastic arm portion is allowed to have the length necessary to obtain the certain elasticity and the contact pressure against the mating terminal without thinning the thickness thereof. Further, the elastic arm portion is allowed to shorten the entire length thereof, making it possible the connector to lower the height thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an electrical connector according to an embodiment of the present invention; 
         FIG. 2  is a sectional view showing the electrical connector and a mating connector according to the embodiment of the present invention; and 
         FIGS. 3(A) and 3(B)  are sectional views showing a terminal of the electrical connector partially, in a region around a contact portion thereof, according to modified examples of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereunder, an electrical connector according to an embodiment of the present invention will be explained with reference to the accompanying drawings. 
       FIG. 1  is a perspective view showing an electrical connector  1  according to an embodiment.  FIG. 2  is a sectional view showing the electrical connector  1  and a mating connector  2  in a state of being unconnected to the electrical connector  1 .  FIGS. 3(A) and 3(B)  are sectional views partially showing a main section of a terminal of the electrical connector  1  according to modified examples, respectively. 
     In the embodiment, the electrical connector  1  (the connector  1 ) is mounted on a circuit board (not shown) and receives the mating connector  2  (described later) to be connected from an upper direction. The connector  1  includes a housing  10  and a plurality of the terminals  20 . The housing  10  has a substantial rectangular parallelepiped shape and made from a synthetic resin. The terminal  20  is made from metal and disposed to be held in the housing  10  in a longitudinal direction of the housing  10 . 
     As shown in  FIG. 1 , the housing  10  includes a bottom wall  11 , a protruding wall portion  12  and a circumferential wall  13  surrounding the protruding wall portion  12 . The bottom wall  11  faces a mounting surface of the circuit board and extends in the longitudinal direction, in other words, a terminal disposing direction. The protruding wall portion  12  protrudes from the bottom wall  11  in the upper direction as well as extending in the longitudinal direction. The circumferential wall  13  includes a pair of sidewalls  14  facing each other and extending in the longitudinal direction and a pair of end walls  15 . 
     In the embodiment, the end wall  15  is connected to end portions of the two sidewalls  14  and extends in a short direction which is perpendicular to the longitudinal direction. The circumferential wall  13  and the protruding wall portion  12  forms a receptacle recess portion  16  having an annular rectangle shape for receiving a fitting portion of the mating connector  2 . The sidewall  14  holds the terminal  20  in the longitudinal direction thereof with a predetermined interval. The housing  10  will be explained again later, in relation to the terminal  20 . 
     The terminal  20  is formed by bending a metal strip in a thickness direction thereof. The terminal  20  has an approximate lateral S-shape including a U-shape portion and an upside-down U-shape portion. The terminals  20  are held in the sidewall  14  of the housing  10 , forming two rows so as to be symmetrical about the protruding wall portion  12 . The terminal  20  includes the held portion  21 , the elastic arm portion  22 , the base portion  23  and a connecting portion  24 . The held portion  21  has the upside-down U-shape held by the sidewall  14  of the housing  10 . 
     In the embodiment, the elastic arm portion  22  extends in a vertical direction at a position close to the protruding wall portion  12  in the short direction and an upper end portion thereof is a free end. The base portion  23  extends along the bottom wall  11  of the housing  10  in the short direction. Further, the base portion  23  connects one leg portion of the held portion  21  (an inner leg portion  21 A, described later) to the elastic arm portion  22  at a lower end position thereof. The connecting portion  24  extends from another leg portion of the held portion  21  (an outer leg portion  21 B, described later) to outside the housing  10 . The connecting portion  24  is soldered to a corresponding circuit portion on the circuit board (not shown). As shown in  FIGS. 1 and 2 , the terminal  20  is held in the housing  10  by being molded integrally with the housing  10  at the held portion  21  thereof. 
     Obviously, the connecting portion  24  extends as necessary as being soldered to the circuit board. In the embodiment, the terminal  20  and the housing  10  are molded integrally. Configurations of holding the terminal are not limited to the case described above. The terminal may be held in the housing by being forcibly inserted into the sidewall. 
     As shown in  FIG. 2 , the held portion  21  has the upside-down U-shape as described above and includes the inner leg portion  21 A and the outer leg portion  21 B. The inner leg portion  21 A extends along an inner surface of the sidewall  14  and the outer leg portion  21 B situated at a position closer to an outer surface of the sidewall  14 . The inner leg portion  21 A includes a locking portion  21 A- 1  at a position close to an upper end thereof. The locking portion  21 A- 1  protrudes into the receptacle recess portion  16  so as to face a contact portion  22 B (described later). 
     In the embodiment, the locking portion  21 A- 1  not only maintains the connector  1  and the mating connector  2  being connected to each other by engaging a locked portion  41 B- 1 , formed by caving in a mating terminal  40  of the mating connector  2 , but also helps the contact portion  22 B by contacting and conducting electrically with the locked portion  41 B- 1 . 
     As shown in  FIGS. 1 and 2 , the held portion  21  is held in the sidewall  14  so as to stride over the sidewall  14 , being buried in the sidewall  14  by being molded integrally. The inner leg portion  21 A of the held portion  21  contacts with the sidewall  14  with a lower surface and side edges thereof. The outer leg portion  21 B of the held portion  21  is buried in the sidewall  14  entirely at an upper half portion thereof and exposes an outer surface thereof at a lower half portion thereof. A highest portion of the held portion  21  connecting the inner leg portion  21 A and the outer leg portion  21 A exposes a surface thereof at a half portion thereof situated inside the connector while being buried entirely in the sidewall  14  at a half portion thereof situated outside the connector. 
     In the embodiment, the connecting portion  24  is formed by being bent and extends in a horizontal direction, from a lower end portion of the outer leg portion  21 B toward outside the housing  10 . As shown in  FIGS. 1 and 2 , the connecting portion  24  is situated approximately in the same height with a lower surface of the bottom wall  11  and capable of being soldered to the corresponding circuit portion on the circuit board. 
     The elastic arm portion  22  extends in the upper direction along the protruding wall portion  12  thorough a transition portion  25  which is formed by being bent at a position between the elastic arm portion  22  and the base portion  23 . The elastic arm portion  22  is capable of elastic displacement in the short direction by being bent in the thickness direction thereof. The elastic arm portion  22  is inclined toward the sidewall  14  as extending in the upper direction toward the free end. The elastic arm portion  22  is thus inclined so as to contact with the mating terminal  40  and have more interference with the mating terminal  40  as the mating connector  2  is inserted when the connector  1  is connected to the mating connector  2 . 
     The elastic arm portion  22  includes a tapered portion  22 A at a position close to the upper end portion thereof. The tapered portion  22 A is formed by reducing a thickness thereof as being closer to the upper end portion of the elastic arm portion  22 . 
     As described above, the elastic arm portion  22  is inclined toward the inner leg portion  21 A as extending to the upper direction. Therefore, the tapered portion  22 A forms a protruding shape at a boundary zone with a portion situated next to a lower end thereof. The boundary zone having the protruding shape thus formed functions as the contact portion  22 B. 
     As shown in  FIG. 2 , the contact portion  22 B has an interference  6  with the mating terminal  40  in lateral direction in  FIG. 2 , in other words, in a direction perpendicular to a connecting direction (a direction the connector  1  is connected to the mating connector  2 ). 
     In addition, as shown in  FIG. 2 , the mating terminal  40  has a surface thereof having the interference  6  in a region corresponding to the tapered portion  22 A. Moreover, the elastic arm portion  22  includes a beveled portion  22 C at an upper edge portion of the tapered portion  22 A, in order to lower a height of the connector  1  furthermore. The beveled portion  22 C may have either of a curved surface or a flat surface. The beveled portion  22 C only has to be situated in a region close to an upper end edge of the elastic arm portion  22 . It is preferable that the beveled portion  22 C is situated within a minimum region capable of guiding the mating terminal  40 . 
     The housing  10  further includes a terminal holding groove  17  in an inner surface of the receptacle recess portion  16 . The terminal holding groove  17  holds the U-shape portion of the terminal  20 . The terminal holding groove  17  includes a bottom wall groove portion  17 A provided on the bottom wall  11  for holding the base portion  23  of the terminal  20  and a protruding wall groove portion  17 B provided on the protruding wall portion  12  for holding the elastic arm portion  22 . The bottom wall groove portion  17 A and the protruding wall groove portion  17 B communicate with each other. 
     In the embodiment, the terminal holding groove  17  further includes a side groove portion  17 C on both edges of the protruding wall groove portion  17 B. The side groove portion  17 C is not deeper than the protruding wall groove portion  17 B. A pair of the side groove portions  17 C next to each other forms a regulating portion  18  for regulating a corresponding portion of the mating connector  2  in a direction perpendicular to the terminal disposing direction. Accordingly, the elastic arm portion  22  is situated between the side groove portions  17 C and displaced elastically into the protruding wall groove portion  17 B as the connector  1  is connected to the mating connector  2 . 
     As the connector  1  is connected to the mating connector  2 , the elastic arm portion  22  partially moves inside the protruding wall groove portion  17 B while the contact portion  22 B and adjacent thereof are situated outside the side groove portion  17 C having a sufficient contact pressure with the mating terminal  40 . In the embodiment, the regulating portion  18  is provided on both sides of each of the protruding wall groove portion  17 B. 
     It is preferable that the regulating portion  18  is provided at positions corresponding to arbitrary two or more of the protruding wall groove portion  17 B only, instead of being provided at a position corresponding to each of the protruding wall groove portion  17 B. Thereby, it is possible to regulate the mating connector certainly at least two positions having a distance in the longitudinal direction by the regulating portion thus provided. The regulating portion may be provided at both ends of the protruding wall in the longitudinal direction. 
     The tapered portion  22 A is able to be formed by crushing locally the upper end portion of the elastic arm portion  22  with an appropriate tool. The tapered portion  22 A is also able to be formed by other method, for example, by grinding the upper end portion of the elastic arm portion  22 . 
     The mating terminal  40  is made by bending a metal strip in a thickness direction thereof and held in a housing  30  being arranged in two rows in a short direction (the lateral direction in  FIG. 2 ) of the housing  30  so as to be symmetrical. The mating terminal  40  includes an engaging portion  41 , an inner leg portion  41 A, a connecting portion  44  and a transition portion  45 . 
     In the embodiment, the engaging portion  41  has a U-shape and the inner leg portion  41 A is one of two leg portions of the engaging portion  41  situated closer to a receptacle recess portion  35 . The engaging portion  41  is held with a sidewall  33 . The connecting portion  44  extends in the short direction from an upper end of the inner leg portion  41 A through the transition portion  45  which is formed by being bent. The connecting portion  44  is soldered to a corresponding circuit portion of a circuit board. As shown in  FIG. 2 , the mating terminal  40  is held in the housing  30  by being molded integrally at the engaging portion  41  and the transition portion  45  thereof. 
     The engaging portion  41  is buried in the sidewall  33  so as to stride the sidewall  33  from a lower direction. The sidewall  33  holds side edges and an inner surface of the engaging portion  41 . An outer surface of the engaging portion  41  being exposed from the sidewall  33  forms a smooth surface with an outer surface of the sidewall  33 . The engaging portion  41  has a slightly larger size in the short direction than a distance between the contact portion  22 B and the locking portion  21 A- 1  of the terminal  20  of the connector  1 . 
     Accordingly, as described above, the contact portion  22 B has the interference  6  with the mating terminal  40 . The engaging portion  41  further includes a corresponding contact portion  41 A- 1  provided at a position closer to a bottom wall  31  (an upper side in  FIG. 2 ), on a plate surface of the inner leg portion  41 A which is situated closer to the receptacle recess portion  35 . The corresponding contact portion  41 A- 1  contacts with the contact portion  22 B of the terminal  20  of the connector  1  with the contact pressure, as the connector  1  and the mating connector  2  are connected to each other. 
     In the embodiment, the corresponding contact portion  41 A- 1  has a slightly recessed shape, thereby locking the contact portion  22 B as contacting with the contact portion  22 B of the terminal  20 . Furthermore, the engaging portion  41  includes the locked portion  41 B- 1  having a recessed shape provided at a position closer to the bottom wall  31  (the upper side in  FIG. 2 ) on an outer surface of an outer leg portion  41 B. The outer leg portion  41 B is one of the two leg portions of the engaging portion  41  being situated distant to the receptacle recess portion  35 . The locked portion  41 B- 1  engages the locking portion  21 A- 1  of the terminal  20 . 
     As shown  FIG. 2 , the connecting portion  44  is situated in approximately the same height with a lower surface (an upper surface in  FIG. 2 ) of the bottom wall  31 . The connecting portion  44  is to be soldered to the corresponding circuit portion of the circuit board. 
     Hereunder, operation of connecting the connector  1  to the mating connector  2  will be explained. First, the connector  1  and the mating connector  2  are soldered to the corresponding circuit portions of the circuit boards, respectively. 
     Next, as shown in  FIG. 2 , the connector  1  is placed so that the receptacle recess portion  16  thereof opens toward the upper direction and the mating connector  2  is placed over the connector  1  so that the receptacle recess portion  35  thereof opens toward the lower direction. Next, the mating connector  2  is moved in the lower direction. Being regulated by the regulating portion  18  formed in the protruding wall portion  12 , the fitting portion of the mating connector  2  is inserted in the receptacle recess portion  16  of the connector  1 . 
     Accordingly, the engaging portion  41  of the mating terminal  40  of the mating connector  2  moves in the connecting direction then abuts against the tapered portion  22 A of the terminal  20  of the connector  1  with a curved portion of the U-shape thereof. Being guided by the tapered portion  22 A in the connecting direction, the engaging portion  41  opens a space between the contact portion  22 B and the locking portion  21 A- 1  of the terminal  20  of the connector  1 . 
     As a result, the elastic arm portion  22  of the terminal  20  is displaced elastically into the protruding wall groove portion  17 B of the terminal holding groove  17  as the contact portion  22 B is pushed into the protruding wall groove portion  17 B. As the engaging portion  41  moves further, the contact portion  22 B contacts with the corresponding contact portion  41 A- 1  of the engaging portion  41  with the contact pressure. 
     In addition, the locking portion  21 A- 1  engages the locked portion  41 B- 1  of the engaging portion  41  in the vertical direction. Consequently, the terminals of the connectors are conducted electrically with each other as well as locking each other. Thereby, the operation connecting the connector  1  to the mating connector  2  is completed. 
     The present invention is able to modify in various ways, not limited to the embodiment described above and shown in  FIGS. 1 and 2 . 
     The contact portion is formed as the boundary zone between the tapered portion and the portion situated next thereto. As opposed to a case that the contact portion is provided on the upper end of the elastic arm portion  22  so as to face the base portion  23  of the terminal  20  as shown in  FIGS. 1 and 2 , it is possible to provide the contact portion so as to face an opposite side of the base potion  23 . 
     As compared to a case shown in  FIGS. 1 and 2 , when the contact portion of the mating connector is inserted into a side where the base portion is not provided as shown in  FIGS. 3(A) and 3(B) , the elastic arm portion  22  of the terminal  20  may include the tapered portion  22 A and the contact portion  22 B at the upper end thereof, on the side where the base portion  23  is not provided. 
     The disclosure of Japanese Patent Application No. 2011-031566 filed on Feb. 17, 2011, is incorporated in the application by reference. 
     While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.