Patent Publication Number: US-6699061-B2

Title: Card connector

Description:
FIELD OF THE INVENTION 
     The present invention relates to a card connector mounted on electronic devices, such as cellular phones, telephones, PDAs (personal digital assistants), portable audio devices and cameras, and more specifically to a structure that prevents contact terminals of the card connector from being deformed by a wrong insertion of a card. 
     BACKGROUND ART 
     In electronic devices such as cellular phones, telephones, PDAs and digital cameras, a variety of functions are added by inserting an IC card with a built-in CPU or memory IC, such as a SIM (subscriber identity module) card, an MMC (multimedia card), and an SD (secure digital or super density) card. 
     In a connector for removably accommodating such an IC card, a plurality of contact terminals made from a metal leaf spring are provided in a connector housing to make contact with a plurality of contact pads formed on the front or back surface of the inserted IC card to electrically connect the IC card to the electronic device mounting that connector. The contact pads of the IC card include a power supply pad connected to a power supply line and a plurality of signal pads for transferring various signals. These contact pads are connected via the contact terminals of the card connector to a power supply circuit and various signal processing circuits in the electronic device. 
     The SD card, one kind of the IC card, is shaped as shown in FIGS. 8A to  8 C and FIG.  9 . FIG. 8 shows a top view of the card and FIG. 9 shows a bottom view of the card. 
     In these figures, the SD card  20  has an upper body portion  21  with a thickness of a. At the front right corner the card has a virtually triangular cut-off corner portion  22  for preventing its erroneous insertion. On the back surface side of the upper body portion  21  is formed a lower body portion  23  having a thickness slightly narrower than that of the upper body portion  21  and a predetermined thickness b. That is, the card  20  has stepped portions  24  formed along its both side edges. 
     On the front part of the lower body portion  23  a plurality of recessed portions (grooves)  26  are formed, separated from each other by a plurality of partition walls  25 . On the bottom surface of these recessed portions  26  are arranged contact pads  27  connected to an IC circuit inside the card. The depth of each recessed portion  26  is almost equal to the height of the lower body portion  23  and therefore the surface of each contact pad  27  is spaced from the front surface of the upper body portion  21  by a distance equal to the thickness a of the upper body portion  21 . On a side surface of the card  20  is arranged a slidable write protect button  28  which is slid to one position to protect the card  20  against being written with data. 
     As an example of connector for accommodating a double-height structure card, such as the SD card described above, the applicant of this invention filed Japanese Patent Application No. 11-316110 entitled “Card Connector Structure” on Nov. 5, 1999. 
     According to the invention of this application, in order to provide a connector that can be used commonly for a double-height thick card  20  such as the SD card above and for a single-height thin card (e.g., MMC card) having almost the same thickness a as the upper body portion  21  of the SD card  20 , both side wall portions of a connector housing are formed with a pair of guide grooves that support and guide both side edges of the upper body portion  21  of the double-height thick card  20  and both side edges of the single-height thin card as they are inserted or withdrawn. These guide grooves support those portions of the two cards which have the same thicknesses a. In this connector, when each of these cards is supported in the connector, the distance from the contact pads  27  of one card to the contact terminals of the connector is equal to the distance from the contact pads  27  of the other card to the contact terminals, so that the both cards engage the contact terminals with the same contact pressures. 
     FIGS. 10A and 10B show the double-height thick card  20  normally inserted into connector  100  of this invention. A base plate of a connector housing  101  has a plurality of contact terminals  102  arranged parallelly thereon. The connector housing  101  has an abutment wall  103  against which the inserted IC card  20  is pushed. At one corner of the abutment wall  103  there is formed a protruding corner wall  104  with which the cut-off corner portion  22  of the IC card  20  engages. In both side wall portions, the above-described guide grooves  105  are formed. These paired guide grooves  105  support both edges of the upper body portion  21  of the card  20 . 
     In FIG.  10 A and FIG. 10B the card  20  is shown to be normally inserted, so contact portions  102   a  of the contact terminals  102  of the connector  100  engage with the contact pads  27  of the SD card  20  with an appropriate pressure. 
     In the connector above, when the card  20  is wrongly inserted back to front as shown in FIG.  11 A and FIG. 11B, the card  20  can be inserted into the connector  100  until its rear end wall  29  abuts against the corner wall  104 . 
     When the card is inserted back to front to such a position, however, the contact portions  102   a  of the contact terminals  102  are in an overloaded state where they are pressed excessively by the bottom surface of the card  20 . In this state, the contact terminals  102  are deformed excessively beyond the elastic limit and undergo plastic deformations. 
     The present invention has been accomplished to overcome this problem. It is therefore an object of this invention to solve the problem by providing a card connector which, if the card is wrongly inserted back to front, can reliably prevent excess deformations of the contact terminals. 
     DISCLOSURE OF THE INVENTION 
     According to one aspect, the present invention provides a card connector for holding a card in a connector housing in such a way that contact pads of the card engage with contact terminals arranged in the connector housing, wherein the card has a plurality of recessed portions formed parallelly in a front part thereof with the contact pads arranged in the recessed portions, the card connector comprising: a pair of guide grooves formed in the connector housing to support and guide both side edges of the card; and a raised portion formed in the connector housing to fit into one of the plurality of recessed portions of the card when the card is inserted into the connector. 
     With this invention, when the card is inserted normally, the raised portion fits into one of the recessed portions in the card for the contact pads. At this time, the contact pads of the card are brought into contact with the contact terminals of the connector without interference from the raised portion. 
     When the card is wrongly inserted back to front, on the other hand, the raised portion works as a stopper and stops the card being inserted before the contact terminals are displaced by the card in excess of their elastic limit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view showing one embodiment of a card connector according to this invention. 
     FIG. 2 is a partly cutaway plan view of the embodiment of FIG.  1 . 
     FIG. 3 is a front view of the embodiment of FIG.  1 . 
     FIG. 4 is a partially enlarged view of FIG.  3 . 
     FIG. 5A is a plan view showing the state of the connector and a card before the card is inserted into the connector. 
     FIG. 5B is a cross section showing the same state as FIG.  5 A. 
     FIG. 6A is a partly cutaway plan view showing the state of the connector and the card when the card is normally inserted. 
     FIG. 6B is a cross section showing the same state as FIG.  6 A. 
     FIG. 7A is a partly cutaway plan view showing the state of the connector and the card when the card is wrongly inserted. 
     FIG. 7B is a cross section showing the same state as FIG.  7 A. 
     FIGS. 8A,  8 B and  8 C are a plan view, a front view and a cross-sectional view of a double-height thick card, respectively. 
     FIG. 9 is a bottom view of the double-height thick card. 
     FIG. 10A is a partly cutaway plan view showing a connector of a previous invention. 
     FIG. 10B is a cross section of FIG.  10 A. 
     FIG. 11A is a partly cutaway plan view showing the card wrongly inserted into the connector of the previous invention. 
     FIG. 11B is a cross section of FIG.  11 A. 
    
    
     PREFERRED EMBODIMENT OF THE INVENTION 
     Now, one embodiment of this invention will be described in detail by referring to the accompanying drawings. 
     FIG. 1 is a plan view showing one embodiment of the card connector according to this invention; FIG. 2 is a partly cutaway plan view showing essential parts of the invention; FIG. 3 is a front view of the connector as seen from the direction of arrow D in FIG. 1; and FIG. 4 is a partially enlarged view of FIG.  3 . FIGS. 5A and 5B show the state of the connector before the IC card is inserted into it. FIG. 5B is a cross section taken along the line V—V of FIG.  5 A. 
     The card connector  1  is mounted on electronic devices such as cellular phones, PDAs, portable audio devices and digital cameras. 
     The connector  1  shown in FIG. 1 to FIG. 5 can accommodate a double-height thick card  20  with stepped portions, such as an SD card shown in FIGS. 8A to  8 C and FIG.  9 . The connector  1  can also accommodate a single-height thin card, such as an MMC card, that has virtually the same shape, size and thickness a as those of the upper body portion  21  of the SD card  20 . 
     In FIG. 1 to FIG. 5, the card connector  1  has a connector housing  30  integrally formed as one piece from an insulating material such as resin. The connector housing  30  is roughly U-shaped in a plan view so as to have side leg portions. 
     The IC card  20  is inserted into the connector  1  through a card insertion opening  11  formed at the front of the housing  30 . 
     The connector housing  30 , as shown in FIG. 5, has an abutment wall  12  that connects both side leg portions and with which the front end portion of the inserted IC card engages. At one corner of the abutment wall  12  where the abutment wall  12  and the side leg portion intersect, a protruding corner wall  13  is formed which engages with the cut-off corner portion  22  of the IC card  20 . 
     As shown in FIG. 3, the IC card  20  is guided and supported at both side edges by a pair of guide grooves  14   a ,  14   b  formed in inner side walls of both side leg portions of the housing  30  as it is inserted and retracted. 
     One of the guide grooves  14   a  extends from a housing front end  19  to the corner wall  13  and the other guide groove  14   b  extends from the housing front end  19  to the abutment wall  12 . The guide grooves  14   a ,  14   b  are formed by upper walls  15 , side walls  16  and lower walls  17  and have their openings directed toward each other. 
     From the edge of the lower wall  17  of each guide groove  14   a ,  14   b  a second side wall  18  extends vertically downwardly almost at a right angle. For each of the second side walls  18 , a second lower wall is formed, and the upper surface of the second lower wall is flush with the upper surface of a base plate  31  of the housing  30 . A space is formed between the two parallel second side walls  18 . 
     The base plate  31  forming the bottom wall of the housing  30  has a plurality of grooves  32  in which a plurality of contact terminals  40  are securely fitted. The contact terminals  40  include power supply terminals and signal terminals. Each of the contact terminals  40  has a terminal portion  40   a  soldered to a contact pad on a printed circuit board of the electronic device, a fixed portion  40   b  securely held in the groove  32 , and a contact spring portion  40   c  elastically displaced to make contact with the contact pad  27  of the card  20 . The contact spring portion  40   c  has a contact portion  40   d  protruding upward in an arc from the fixed portion  40   b.    
     Both side walls forming each of the grooves  32 , as shown in FIG. 4, have press-fit grooves (recessed portions)  34  in which left and right side edges of the fixed portion  40   b  of the contact terminal  40  are fitted under pressure. These recessed portions  34  rigidly support the fixed portion  40   b  of each contact terminal  40 . 
     These contact terminals  40  make electrical connection between the card  20  and the electronic device and at the same time provide an appropriate card holding force by their elasticity. 
     On both sides of the groove  32  that rigidly supports the rightmost contact terminal  40 , when viewed from the card insertion opening  11 , a pair of raised portions (referred to as ribs)  50  are arranged on the base plate  31  to extend along both sides of the contact terminal  40 . The ribs  50  are formed integral with the base plate  31 . The pair of the ribs  50  have their positions, widths and heights so set that when the card  20  is normally inserted, they fit into one  26   a  of grooves  26  formed between separation walls  25  of the card  20  which is located near the cut-off corner portion  22  (see FIG.  5 A and FIG.  5 B). 
     These paired ribs  50  function as stoppers that, when the card  20  is wrongly inserted back to front, prevent the card  20  from being inserted to the fully inserted position. 
     FIG.  6 A and FIG. 6B show the card  20  normally inserted into the connector. 
     When the card  20  is normally inserted into the connector  1 , the side surfaces of the upper body portion  21  of the card  20  are guided by the side walls  16  of the guide grooves  14   a ,  14   b  and the side edge portions of the bottom surface of the upper body portion  21 , i.e., the stepped portions  24 , are supported and guided by the lower walls  17 . The floating of the card  20  due to the elastic force of the contact terminals  40  is prevented by the side edge portions of the top surface of the upper body portion  21  being restricted by the upper walls  15  of the guide grooves  14   a ,  14   b . The lower body portion  23  of the card  20  is accommodated in the space between the second side walls  18 . 
     The card  20  can be inserted into the connector to a position where its cut-off corner portion  22  and front end wall engage with the corner wall  13  and the abutment wall  12 , respectively. With the card  20  inserted to this position, the pair of ribs  50  formed on the base plate  31  of the housing  30  fit into the groove  26   a  of the card  20  adjoining the cut-off corner portion  22  of the card  20 . At this time, the contact portion  40   d  of the contact terminal  40  projecting from between the paired ribs  50  is pressed and elastically deformed by the contact pad  27  provided in the groove  26   a  of the card  20 , making elastic contact with the contact pad  27  with an appropriate contact pressure. Other contact terminals  40  not provided with the ribs  50  also engage with associated contact pads  27  with an appropriate contact pressure. 
     FIG.  7 A and FIG. 7B show the card  20  wrongly inserted back to front into the connector. 
     In this case, too, the card  20  can be inserted into the connector with the upper body portion  21  supported by the guide grooves  14   a ,  14   b . However, because the rear part of the card  20  is not formed with the grooves  26  as is the front part, if the card  20  is wrongly inserted back to front, the rear end wall  29  of the card  20  abuts against the front end face of the ribs  50  at some point on the way, blocking a further insertion of the card. Hence, with this connector, because the card  20  cannot be inserted any further as it can with the conventional connector, the contact terminals  40  can be prevented from being overloaded and displaced beyond its elastic limit. 
     In this embodiment, because the stopper structure formed by the pair of ribs  50  is provided, if the card is wrongly inserted back to front, it is possible to block the insertion of the card  20  before the contact terminals  40  are displaced in excess of their elastic limit, thus preventing plastic deformation of the contact terminals  40 . 
     In the connector  1  of the embodiment above, because the cantilevered contact terminals  40  are arranged to have the terminal portion  40   a  on the front side of the connector  1  and the contact portion  40   d  on the rear side of the connector  1 , the area occupied by the connector  1  can be made smaller than when their arrangements are reversed. That is, when the orientations of the contact terminals  40  are reversed from the above, the terminal portion  40   a  is exposed outside the housing of the connector  1  and the occupied area increases to that extent. 
     The ribs  50  can be made to function as the stopper as long as the ribs  50 , when the card  20  is inserted, can fit into any one of the grooves  26  without hindering the contact between the contact terminals  40  and the contact pads  27 . That is, the ribs  50  do not need to be provided in a pair on both sides of the contact terminal  40  as in the embodiment above but may be arranged to cover the contact terminal  40  from above (i.e., the ribs may cross the contact terminal  40 ). 
     But, providing the ribs  50  at the sides of the groove  32 , in which the contact terminal  40  is press-fitted, as in the embodiment above has the advantage of facilitating the process of press-fitting the contact terminal  40  in the card insertion direction into the recessed portions  34  formed in the inner walls of the groove  32  because there is no hindrance above the contact terminal  40 . 
     While in the embodiment above the ribs  50  are provided on both sides of the contact terminal  40 , a rib  50  may be provided on one side only. 
     Further, although in the embodiment above the ribs  50  are provided adjoining the contact terminal  40  whose contact portion  40   d  is situated nearest to the front side of the connector (card insertion opening side) among the plurality of contact terminals  40  (in this case, a contact terminal  40  situated in front of the corner wall  13 ), they may be arranged to adjoin any other contact terminal  40 . Alternatively, the ribs  50  may be provided at different positions adjoining a plurality of contact terminals  40 . 
     While in the embodiment above, the ribs  50  are applied to the connector construction that supports both side edges of the upper body portion  21  of the card  20  by the guide grooves  14   a ,  14   b  formed in the connector housing  30 , they can also be applied, with similar effects, to a connector construction that supports the bottom surface of the card  20 , i.e., the lower body portion  23 . 
     While in the embodiment above the top plate of the connector housing  30  covers only the guide grooves  14   a ,  14   b , the abutment wall  12  and its vicinity, it may cover entire surface or most of the card. 
     Further, the connector housing may be constructed of a plurality of housing members, for example, an upper housing made from a worked metal plate and a lower housing made from resin. 
     In the embodiment above, because the card  20  is inserted with its contact pad arranged surface facing down, the contact terminals  40  are arranged on the base plate  31  of the connector housing  30 . In a connector in which the card  20  is inserted with its contact pad arranged surface facing up, the contact terminals  40  may be arranged on the top plate of the connector housing  30 . In such a connector, the pair of ribs  50  need to be provided on the top plate of the connector housing  30 . 
     Further, while the embodiment above uses the connector for the SD card, the present invention can be applied to connectors for any card as long as the card is of a type that has a plurality of recessed portions  26  formed in its front part with contact pads  27  arranged at the bottoms of the recessed portions  26 . For example, the present invention can also be applied to a connector designed for use with a card which has no stepped portions  24  at its side edges. 
     Industrial Applicability 
     As explained above, because the connector housing is provided with a raised portion which, when the card is inserted into the connector, fits into one of the recessed portions formed at the contact pad portions of the card, this raised portion works as a stopper when the card is wrongly inserted back to front. This stopper stops the card being inserted before the contact terminals are displaced in excess of their elastic limit. Thus, the plastic deformation of the contact terminals can be prevented reliably.