Patent Publication Number: US-8523614-B2

Title: Card socket

Description:
This application is a U.S. National Phase Application under 35 USC 371 of International Application PCT/JP2009/001404 filed Mar. 27, 2009. 
     TECHNICAL FIELD 
     The present invention relates to a card socket used for a small-sized electronic device, such as a cellular phone, and more particularly to a card socket for receiving at least part of a card such as a memory card. 
     BACKGROUND ART 
     For example, card sockets disclosed in Patent Literatures 1 to 3 have been known as this type of card sockets. Among others, the card socket disclosed in Patent Literature 2 has a structure capable of reducing the thickness of the card socket as compared to the card sockets of Patent Literatures 1 and 3. 
     Generally, card sockets developed in recent years have a switch for detecting insertion and ejection of a card as with the card socket disclosed in Patent Literature 3.
     Patent Literature 1 JP-A 2005-228519   Patent Literature 2 JP-A 2008-53124   Patent Literature 3 JP-A 2007-242634   

     DISCLOSURE OF INVENTION 
     Problem(s) to be Solved by the Invention 
     As described above, an object of the card socket of Patent Literature 2 is to reduce its thickness. However, a housing of the connector has: a function of holding a plurality of members including contacts; a guide portion for guiding a card; and a part that receives a load from a coiled spring. Therefore, the shape of the housing becomes complicated. The housing has thin portions and thick portions at a plurality of locations. It is relatively difficult to form such a housing of resin with a reduced thickness. Furthermore, there is a problem that the strength of a housing having a complicated structure becomes low if the thickness of the card socket is reduced. 
     Additionally, in the case of the card socket of Patent Literature 2, it is structurally difficult to provide a detection switch as illustrated in Patent Literature 3 without an increase of the size of the card socket. 
     Therefore, an object of the present invention is to provide a card socket having a simple structure capable of achieving reduction in thickness. 
     Means to Solve the Problem 
     According to the present invention, there is provided a first card socket having a base frame made of metal, the base frame having a first part and a second part extending along a first direction and a connection portion connecting the first part and the second part to each other so that the first part and the second part are separated from each other in a second direction perpendicular to the first direction; a housing provided so as to bridge between the first part and the second part of the base frame in the second direction; a contact held on the housing; and a cover made of a metal material that is separate from the base frame, the cover being combined with the base frame so as to cover the housing in a third direction perpendicular to both of the first direction and the second direction, the cover constituting a card receiver for receiving at least part of a card along with the base frame. 
     Effect(s) of the Invention 
     According to the present invention, since the contact is held on the housing, which bridges between the first part and the second part of the base frame, the thickness of the card socket can be reduced with a simple structure. 
     Additionally, according to the present invention, there is no positional limitations that have been imposed on holding portions for holding the contacts of Patent Literature 2. In the card socket of Patent Literature 2, contact portions of the contacts are arranged between held portions and a rear end of the card socket in an insertion direction of a card. The contacts (the contact portions in particular) need to be formed and arranged so as not to interfere with an inserted card when the card is inserted from the rear end toward a front end of the card socket. Specifically, tip portions of the contacts should be bent downward so that the contacts can guide the inserted card smoothly. Without such a configuration, the contact portions of the contacts would be brought into contact with terminals of the card and would possibly be deformed. In such a case, there would be a restriction that a margin is required in the thickness direction. This restriction would limit reduction in thickness of the card socket. In contrast, such a restriction is eliminated if the contacts are arranged so that the contact portions of the contacts are located closer to the front end of the card socket than the held portions of the contacts are. Therefore, according to the present invention, further reduction in thickness can be achieved as compared to the card socket of Patent Literature 2. Moreover, since the base frame of the card socket according to the present invention has the connection portion, the strength is advantageously increased in the second direction as compared to the card socket of Patent Literature 2. 
     Furthermore, according to the present invention, the first switch piece, which constitutes the detection switch, is formed integrally with the cover. Therefore, even if a normally-closed type detection switch is used, deformation of components of the card socket (e.g., deformation of resin of the housing and positional deviation of the switch pieces caused by such deformation) can be reduced at the time when reflow mounting is carried out. The normally-closed type refers to a type in which the first switch piece and the second switch piece are in contact with each other before the card has been inserted. Particularly, when the backup part is provided on the metal member (e.g., the base frame of the present invention or a metal member separately incorporated in a housing of the prior art), which is combined with the cover, the risk of deformation of the components of the card socket can further be reduced at the time of the reflow mounting. In this case, a force applied to the second switch piece by contact of the first switch piece and the second switch piece is received via the switch piece holding housing in the first direction by the backup part. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing a card socket according to an embodiment of the present invention. 
         FIG. 2  is a perspective view showing a state in which a card has been received in the card socket of  FIG. 1 . 
         FIG. 3  is an exploded perspective view showing the card socket of  FIG. 1 . 
         FIG. 4  is a view showing a layout prior to formation of a housing by using a mold-in-place method. 
         FIG. 5  is a perspective view showing a contact of  FIG. 4 . 
         FIG. 6  is a cross-sectional view showing the housing, the contacts, and a base frame taken along line VI-VI of  FIG. 3 . 
         FIG. 7  is a perspective view showing a cover of  FIG. 3  as viewed obliquely from below the cover. 
         FIG. 8  is a cross-sectional view showing the base frame and the cover taken along line VIII-VIII of  FIG. 1 . 
         FIG. 9  is a top view showing the card socket of  FIG. 1 , from which a primary portion of the cover is omitted for clarifying a structure of a detection switch. 
         FIG. 10  is a cross-sectional view showing the detection switch taken along line X-X of  FIG. 9 . 
     
    
    
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
         
           
               100  Base frame 
               110  First part 
               112  Raised portion 
               114  Through hole 
               120  Second part 
               122  Raised portion 
               124  Recessed portion 
               130  First connection portion 
               140  Second connection portion (backup part) 
               150 ,  160  Side portion 
               170  Engaging piece 
               200  Housing 
               210  Part 
               220  Part 
               300  Contact 
               310  Spring portion 
               312  Contact portion 
               314  Tip portion 
               320  Held portion 
               322  Recessed portion 
               330  Fixed portion 
               400  Ejection mechanism 
               410  Slider 
               420  Cam follower 
               430  Coiled spring 
               500  Cover 
               510  Primary portion 
               520  Side portion 
               530  Front portion 
               540  Engaged hole 
               600  Detection switch 
               610  First switch piece 
               620  Second switch piece 
               700  Switch piece holding housing 
               720  Shaft hole 
               730  Grease stopper 
               800  Card receiver 
               900  Card 
           
         
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     A card socket according to an embodiment of the present invention is a card socket for a MicroSD card and is of a so-called push-push type. Particularly, the present invention relates to a card socket mounted on a cellular phone or the like by reflow soldering. 
     As shown in  FIGS. 1 to 3 , the card socket according to this embodiment has a base frame  100  made of metal, a housing  200  supported on the base frame  100 , contacts  300  held on the housing  200 , an ejection mechanism  400  configured to eject a card  900 , a cover  500  made of metal, which covers the housing  200  and the contacts  300 , a detection switch  600  configured to detect insertion of the card  900 , and a switch piece holding housing  700  for holding part of the detection switch  600 . The housing  200  and the switch piece holding housing  700  of this embodiment are made of resin. 
     As shown in  FIGS. 3 and 4 , the base frame  100  includes a first part  110 , a second part  120 , a first connection portion  130 , a second connection portion  140 , and side portions  150  and  160 . The first part  110  and the second part  120  extend along the Y-direction (first direction). Each of the first connection portion  130  and the second connection portion  140  connects the first part  110  and the second part  120  to each other in a state in which the first part  110  and the second part  120  are spaced from each other in the X-direction (second direction). 
     The side portion  150  is formed on an outer edge of the first part  110  in the X-direction. The side portion  150  rises in the Z-direction. Meanwhile, a raised portion  112  is formed on an inner edge of the first part  110 . The raised portion  112  rises in the Z-direction. Through holes  114  are formed in the raised portion  112 . The raised portion  112  serves to prevent the housing  200  from coming off as described later. Furthermore, the raised portion  112  also serves to prevent the base frame  100  from being bent in the Z-direction. 
     The side portion  160  is formed on an outer edge of the second part  120  in the X-direction. The side portion  160  rises in the Z-direction. A raised portion  122 , which rises in the Z-direction, is formed on the outer edge of the second part  120 . A recessed portion  124 , which is recessed in the Z-direction, is formed in the raised portion  122 . 
     As shown in  FIGS. 4 ,  6 , and  8 , engaging pieces  170  are formed on each of the side portions  150  and  160 . The engaging pieces  170  project toward an outside of a card slot in the X-direction. As is apparent from  FIG. 4 , the raised portion  122  of this embodiment is formed as part of the side portion  160 . 
     As shown in  FIGS. 3 and 6 , the housing  200  extends along the X-direction. The housing  200  is provided so as to bridge a space between the first part  110  and the second part  120  of the base frame  100  in the X-direction. As can be seen from  FIGS. 3 and 4 , the housing  200  is located between the first connection portion  130  and the second connection portion  140  in the Y-direction. Therefore, as shown in  FIGS. 3 and 6 , the housing  200  does not overlap the base frame  100  between the first part  110  and the second part  120  in the Z-direction. As can be seen from  FIGS. 3 ,  4 , and  6 , a part  210  extending along the Y-direction is formed on an end of the housing  200 . The part  210  has such a shape as to sandwich the raised portion  112  in the X-direction. Furthermore, the part  210  is also situated within the through holes  114 . Thus, the housing  200  is prevented from coming off the first part  110 . A part  220  extending along the Y-direction is formed on another end of the housing  200 . The part  220  has a part  222  projecting toward an outside of the card socket in the X-direction. That part extends along the Y-direction. Specifically, the part  222  of the housing  200  sandwiches the raised portion  122  in the X-direction. The part  222  of the housing  200  is situated within the recessed portion  124  of the raised portion  122 . As is apparent from  FIG. 9 , the size of the part  222  of the housing  200  is larger than the size of the recessed portion  124  in the Y-direction. Therefore, the housing  200  is also prevented from coming off the second part  120 . 
     As shown in  FIG. 5 , the contact  300  has a spring portion  310  having a contact portion  312 , a held portion  320  held by the housing  200 , and a fixed portion  330  fixed to a pattern on a circuit board on which the card socket is mounted. A recessed portion  322 , which is recessed in the Z-direction, is formed on the held portion  320 . As shown in  FIGS. 3 and 6 , the contacts  300  are held on the housing  200  in a state in which the recessed portions  322  are embedded in the housing  200 . Thus, the contacts  300  are prevented from coming off the housing  200 . Furthermore, as can be seen from  FIGS. 3 and 6 , the contacts  300  are arranged on a plane that is different from the plane of the first connection portion  130  of the base frame  100 . Specifically, the contacts  300  are located at positions that are different from the position of the first connection portion  130  of the base frame  100  in the Z-direction. Accordingly, the first connection portion  130  does not inhibit contact of the contacts  300  and terminals of the card  900 . Furthermore, as shown in  FIG. 6 , the bottom of the housing  200  and the bottoms of the first part  110  and the second part  120  are located on the same plane. Therefore, the thickness of the card socket can be reduced. As shown in  FIG. 1 , the first connection portion  130  and the cover  500  define an insertion slot in the present embodiment. The insertion slot is located on a rear end of the card socket. In the present embodiment, the card is inserted from the insertion slot toward a front end of the card socket. In other words, the card is inserted into the card socket from the rear end toward the front end of the card socket. The direction from the rear end to the front end of the card socket is referred to as an insertion direction. As shown in  FIG. 3 , the contact portions  312  of the contacts  300  are located between the held portions  320  and the front end of the card socket in the insertion direction. The fixed portions  330  are located between the held portions  320  and the rear end of the card socket in the insertion direction. With this arrangement, tip portions  314  of the contacts  300  do not inhibit insertion of the card  900 . Accordingly, the height H of the contact portions  312  from the tip portions  314  can be reduced in the present embodiment. (For example, the height H can be made zero.) A conventional card socket needs a margin for preventing the tip portions  314  from contacting a circuit board at the time of flexural deformation of the spring portions  310 . According to the present invention, however, such a margin can be reduced. Therefore, the thickness of the card socket can be reduced as compared to the card socket as disclosed in Patent Literature 2, which needs a large margin. 
     As shown in  FIGS. 3 and 9 , the ejection mechanism  400  of this embodiment includes a slider  410  with a cam, a cam follower  420 , and a coiled spring  430 . The cam follower  420  follows the cam of the slider  410 . The coiled spring  430  biases the slider  410  toward a ejection direction. The ejection mechanism  400  is arranged on the first part  110 . 
     As shown in  FIGS. 3 and 7 , the cover  500  includes a primary portion  510 , which forms an upper surface of the card socket, side portions  520 , and a front portion  530 . The side portions  520  extend along the Z-direction from opposite ends of the primary portion  510  in the X-direction. The front portion  530  extends along the Z-direction from a front end of the primary portion  510 . As shown in  FIG. 1 , the cover  500  and the base frame  100  are combined with each other so as to constitute a card receiver  800 . As can be seen from  FIGS. 1 and 2 , the card  900  is received in the card receiver  800  except a rear end of the card  900 . Engaged holes  540  penetrating the side portions  520  in the X-direction are formed in the side portions  520  of the cover  500 . As shown in  FIGS. 1 and 8 , the engaging pieces  170  of the base frame  100  engage with the engaged holes  540 . Thus, the combination of the base frame  100  and the cover  500  is maintained. Furthermore, a movement of the base frame  100  relative to the cover  500  is restricted in the Y-direction by the engagement of the engaging pieces  170  and the engaged holes  540 . 
     As shown in  FIGS. 1 and 9 , the detection switch  600  is a normally-closed type switch provided in front of the contacts  300 . The detection switch  600  includes a first switch piece  610  and a second switch piece  620 . The first switch piece  610  and the second switch piece  620  are brought into contact with each other in the Y-direction. Specifically, with the detection switch  600  of this embodiment, the first switch piece  610  and the second switch piece  620  are in contact with each other when the card  900  has not been inserted. The first switch piece  610  and the second switch piece  620  are out of contact with each other when the card  900  has been inserted. As shown in  FIG. 7 , the first switch piece  610  is formed integrally with the cover  500 . Therefore, the first switch piece  610  has a sufficient spring force. On the other hand, the first switch piece  610  is prevented from being deformed. In contrast, as shown in  FIGS. 9 and 10 , the second switch piece  620  is held by the switch piece holding housing  700 . The switch piece holding housing  700  is supported on the second connection portion  140  of the base frame  100 . The present embodiment describes an example in which the base frame  100  is made of metal. However, the first switch piece  610  can also be formed integrally with the cover  500 , for example, in a manner similar to a base housing disclosed in Patent Literature 3. 
     As can be seen from  FIG. 10 , the second switch piece  620  receives a force from the first switch piece  610  in the Y-direction. The second connection portion  140  serves as a backup part that receives the force via the switch piece holding housing  700 . Specifically, since the detection switch  600  of this embodiment is of a normally-closed type, the first switch piece  610  and the second switch piece  620  receive forces from each other in the Y-direction when the card  900  has not been inserted. The force received by the second switch piece  620  is transmitted to the switch piece holding housing  700 . If there is no backup part, the switch piece holding housing  700  may be deformed to a large extent by heat at the time when reflow mounting is carried out. According to the present embodiment, however, the second connection portion (backup part)  140  backs up the second switch piece  620  via the switch piece holding housing  700  in the Y-direction. Resin is weak to bending stress and tensile stress but is relatively strong against compressive stress. Therefore, provision of the second connection portion  140  prevents deformation of the switch piece holding housing  700 . 
     Furthermore, the backup part of this embodiment, i.e., the second connection portion  140  is formed as part of the base frame  100 . Moreover, the base frame  100  can be combined with the cover  500 . Therefore, a force applied to the second switch piece  620  by the first switch piece  610  is transmitted to the engagement portions of the engaging portions  170  and the engaged holes  540  via the switch piece holding housing  700  and the base frame  100 . Meanwhile, a force applied to the first switch piece  610  by contact of the first switch piece  610  and the second switch piece  620  is transmitted to the engagement portions of the engaging portions  170  and the engaged holes  540  via the cover  500 . As a result, the forces applied to the first switch piece  610  and the second switch piece  620  by contact of the first switch piece  610  and the second switch piece  620  are cancelled at the engagement portions of the engaging portions  170  and the engaged holes  540 . In other words, a system of transmission of forces is closed within the card socket. Thus, the balance is maintained within the card socket, and problems such as strain do not arise. In the present embodiment, the backup part is formed as part of the base frame  100  (i.e., the second connection portion  140 ). However, the backup part may be formed of any metal member that can ultimately be combined with the cover  500 . For example, the backup part may be separated from the base frame  100 . Specifically, the second connection portion  140  and the side portions  150  and  160  may be formed of a metal member that is separate from the base frame  100 . The present embodiment describes an example in which the base frame  100  is made of metal. However, for example, the backup part for the second switch piece  620  of the detection switch  600  may be provided in a structure having a base housing as in Patent Literature 3. 
     In the present embodiment, the switch piece holding housing  700  is formed integrally with the housing  200 . The switch piece holding housing  700  is formed in the same process as a formation process of a housing that serves as an shaft hole  720  for the cam follower  420  and a housing that serves as a grease stopper  730 . However, the present invention is not limited to this example. For example, the switch piece holding housing  700  may be formed separately from the housing  200 . 
     As described above, in the embodiment of the present invention, a base part of the card socket is basically formed by the base frame  100  made of metal. In other words, no resin is used except for portions essentially required for holding the contacts  300 , maintaining electrical insulation, and the like. Therefore, the thickness of the card socket can be reduced while the strength of the card socket is maintained. 
     Furthermore, in the embodiment of the present invention, the first connection portion  130  and the second connection portion  140  are provided. Accordingly, the rigidity is maintained in the X-direction. Thus, the strength is improved as compared to the structure of Patent Literature 2. 
     Additionally, in the embodiment of the present invention, one of the switch pieces (the first switch piece  610 ), which constitute the detection switch  600 , is formed integrally with the cover  500 . Therefore, the strength of the detection switch  600  can be improved. Furthermore, for the rest of the switch pieces (the second switch piece  620 ), the backup part (the second connection portion  140 ) is provided. Accordingly, it is possible to prevent deformation of resin at the time when reflow mounting is carried out, which would be problematic particularly in a normally-closed type detection switch.