Abstract:
An insulative casing has a bottom face to be mounted on a board member. A conductive pin is disposed in the casing so as to be slidable in a first direction parallel to the bottom face. A conductive terminal is disposed in the casing and has at least one elastic piece which is always brought into contact with an outer periphery of the pin from a second direction perpendicular to the first direction. An elastic member is disposed between the pin and the terminal so that a tip end of the pin is projected from the casing while being retractable in the first direction.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a spring connector which has high reliability and can be manufactured at low cost.  
         [0002]      FIGS. 9A  to  11 C show a conventional spring connector disclosed in Japanese Patent Publication No. 2003-17173A.  
         [0003]     The conventional spring connector comprises a plate-shaped terminal  10  made of conductive material, a conductive pin  12  which can slide with respect to the terminal  10 , a coil spring  14  which is provided between the terminal  10  and the conductive pin  12  in a compressed state, and a holder  16  formed of insulating resin.  
         [0004]     The terminal  10  is formed of an elongated sheet metal which has been folded to form a substantially U-shape as shown in  FIG. 11C . A dented part  10   a  which opens in a forward direction is formed in one of the folded halves of the terminal  10 , and a small protrusion  10   b  is formed at a center of a bottom edge of the dented part  10   a , as shown in  FIGS. 11A and 11B . The other of the folded halves serves as a connecting part  10   c  to be fixed by soldering or so to a circuit board (not shown).  
         [0005]     The conductive pin  12  has a plunger part  12   a  having a relatively small diameter at its tip end side and a protruded part  12   b  having a relatively large diameter at its base end side. This protruded part  12   b  is provided with axially extending grooves  12   c  on both sides thereof. These grooves  12   c  are adapted to be engaged with opposed inner edges of the dented part  10   a  in the terminal  10 , and the conductive pin  12  is arranged so as to slide with respect to the terminal  10  along the grooves  12   c , as guides for the sliding movement. The conductive pin  12  is further provided with a blind hole  12   d  in an axial direction form its base end face. The terminal  10  and the conductive pin  12  may be plated with gold as required.  
         [0006]     Then, the conductive pin  12  is slidably incorporated into the holder  16  such that a tip end of the plunger part  12   a  is projected from the holder  16  so as not to be pulled out. The terminal  10  appropriately fixed to the conductive pin  12  is also incorporated into the holder  16 . The conductive pin  12  is so designed as to be slidable in an axial direction thereof and in a diagonal direction with respect to a bottom face of the holder  16 . In this state, the coil spring  14  is provided in a compressed state between the conductive pin  12  and the bottom edge of the dented part  10   a  in the terminal  10 , having its one end inserted into the blind hole  12   d  in the conductive pin  12  and the other end blocked by the protrusion  10   b  at the center of the bottom edge of the dented part  10   a  in the terminal  10  so as not to be displaced. Moreover, the connecting part  10   c  of the terminal  10  is disposed on the bottom face of the holder  16 .  
         [0007]     In this example, when a contact terminal  18  comes into contact with the tip end of the plunger part  12   a  of the conductive pin  12  in a direction parallel with the bottom face of the holder  16 , as shown in  FIG. 9B , the conductive pin  12  moves diagonally downward, while compressing the coil spring  14  along the inner edges of the dented part  10   a  in the terminal  10 , as the guides. On this occasion, a force F in  FIG. 9B  is exerted on the conductive pin  12  in a direction of prying it, and the grooves  12   c  of the conductive pin  12  are strongly pressed against the inner edges of the dented part  10   a  in the terminal  10 . In this manner, electrical connection between the conductive pin  12  and the terminal  10  can be reliably obtained.  
         [0008]     In order to reliably obtain the electrical connection between the conductive pin  12  and the terminal  10 , it is necessary for the conductive pin  12  to be pushed into the holder  16  in a direction inclined at a certain angle with respect to the bottom face of the holder, but not in parallel with the bottom face. In other words, the direction of pushing in the conductive pin  12  is so set as to be inclined at a certain angle with respect to a direction of movement of the contact terminal  18 . Consequently, a height of the conductive pin  12  from the bottom face is increased by the amount of the inclination.  
       SUMMARY OF THE INVENTION  
       [0009]     It is therefore an object of the invention to provide a spring connector in which even though a sliding direction in an conductive pin is in parallel with a bottom face of a holder, electrical connection between the conductive pin and a plate-shaped terminal can be reliably obtained.  
         [0010]     In order to achieve the above object, according to the invention, there is provided a spring connector, comprising:  
         [0011]     an insulative casing, having a bottom face to be mounted on a board member;  
         [0012]     a conductive pin, disposed in the casing so as to be slidable in a first direction parallel to the bottom face;  
         [0013]     a conductive terminal, disposed in the casing and having at least one elastic piece which is always brought into contact with an outer periphery of the pin from a second direction perpendicular to the first direction; and  
         [0014]     an elastic member, disposed between the pin and the terminal so that a tip end of the pin is projected from the casing while being retractable in the first direction.  
         [0015]     With the above configuration, since the elastic piece is always brought into contact with the conductive pin, the electrical connection between the pin and the terminal can be reliably established even if the sliding direction of the pin is made parallel with the bottom face of the casing. Accordingly, the height dimension of the spring connector can be reduced.  
         [0016]     Preferably, a pair of grooves are formed on both side portions of the pin so as to extend in the first direction. A pair of guide members are formed on one of the terminal and the casing so as to be fitted into the grooves, respectively. Each of the guide members comes in slide contact with an inner face of each of the grooves when the elastic piece is brought into contact with the pin.  
         [0017]     In a case where the guide members are provided as a part of the terminal, since the guide members are brought into slide contact with the pin, the reliability of the electrical connection is further enhanced.  
         [0018]     In a case where the guide members are provided as a part of the casing, since the guide members are monolithically molded with the casing made of resin or the like, the weight of the spring connector can be reduced. Furthermore, the shape of the terminal can be simplified.  
         [0019]     Preferably, two elastic pieces are brought into contact with the pin from opposite sides.  
         [0020]     Here, it is preferable that the elastic pieces are brought into contact with different positions in the first direction. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]     The above objects and advantages of the present invention will become more apparent by describing in detail preferred exemplary embodiments thereof with reference to the accompanying drawings, wherein:  
         [0022]      FIG. 1A  is a vertical section view of a spring connector according to a first embodiment of the invention;  
         [0023]      FIG. 1B  is a section view taken along a line IB-IB in  FIG. 1A ;  
         [0024]      FIG. 1 C  is a section view taken along a line IC-IC in  FIG. 1A ;  
         [0025]      FIG. 2A  is a top view of a terminal in the spring connector of  FIG. 1A ;  
         [0026]      FIG. 2B  is a front view of the terminal of  FIG. 2A ;  
         [0027]      FIG. 2C  is a side view of the terminal of  FIG. 2A ;  
         [0028]      FIG. 3A  is a top view of a conductive pin in the spring connector of  FIG. 1A ;  
         [0029]      FIG. 3B  is a front view of the conductive pin of  FIG. 3A ;  
         [0030]      FIG. 3C  is a side view of the conductive pin of  FIG. 3A ;  
         [0031]      FIG. 4A  is a vertical section view of a spring connector according to a second embodiment of the invention;  
         [0032]      FIG. 4B  is a vertical section view of the spring connector of  FIG. 4A , showing a state that a conductive pin is retracted by a contact terminal;  
         [0033]      FIG. 5A  is a top view of a terminal in the spring connector of  FIG. 4A ;  
         [0034]      FIG. 5B  is a front view of the terminal of  FIG. 4A ;  
         [0035]      FIG. 5C  is a side view of the terminal of  FIG. 4A ;  
         [0036]      FIG. 6A  is a vertical section view of a spring connector according to a third embodiment of the invention;  
         [0037]      FIG. 6B  is a section view taken along a line VIB-VIB in  FIG. 6A ;  
         [0038]      FIG. 7A  is a top view of a terminal in the spring connector of  FIG. 6A ;  
         [0039]      FIG. 7B  is a front view of the terminal of  FIG. 6A ;  
         [0040]      FIG. 7C  is a side view of the terminal of  FIG. 6A ;  
         [0041]      FIG. 8A  is a top view of a terminal in a spring connector according to a fourth embodiment of the invention;  
         [0042]      FIG. 8B  is a front view of the terminal of  FIG. 8A ;  
         [0043]      FIG. 8C  is a side view of the terminal of  FIG. 8A ;  
         [0044]      FIG. 9A  is a vertical section view of a conventional spring connector;  
         [0045]      FIG. 9B  is a vertical section view of the spring connector of  FIG. 9A , showing a state that a conductive pin is retracted by a contact terminal;  
         [0046]      FIG. 10  is a section view taken along a line X-X in  FIG. 9A ;  
         [0047]      FIG. 11A  is a top view of a terminal in the spring connector of  FIG. 9A ;  
         [0048]      FIG. 11B  is a front view of the terminal of  FIG. 11A ; and  
         [0049]      FIG. 11C  is a side view of the terminal of  FIG. 11A . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0050]     Embodiments of the invention will be described below in detail with reference to the accompanying drawings.  
         [0051]     First, with reference to  FIGS. 1A  to  3 C, a spring connector according to a first embodiment will be described.  
         [0052]     The conductive pin  12  as shown in  FIGS. 3A  to  3 C, which is the same as the one employed in the above described conventional example, has a plunger part  12   a , a protruded part  12   b , grooves  12   c , and a blind hole  12   d . A plate-shaped terminal  20  formed of conductive material is made of an elongated sheet metal which has been folded into halves in a substantially U-shape, as shown in  FIG. 2C . One of the folded halves is divided lengthwise into three parts, namely, a center part and both side parts as shown in  FIGS. 2A and 2B . The both side parts are formed substantially in parallel with the other of the folded halves which serves as a connecting part  20   a , and inside edges of the both side parts are opposed in parallel with each other to form guide parts  20   b.    
         [0053]     The center part is formed as an elastic contact part  20   c  which is adapted to be brought into elastic contact with the conductive pin  12  from above. When the inner edges of the guide parts  20   b  are engaged with the grooves  12   c  in the conductive pin  12 , the conductive pin  12  is allowed to slide by the aid of the guide parts  20   b . It is apparent that the elastic contact part  20   c  is brought into elastic contact with the conductive pin  12  within a sliding range of the conductive pin  12 .  
         [0054]     Moreover, the terminal  20  is provided with a protrusion  20   d  for blocking the coil spring  14  from being displaced at its base end side. Then, the coil spring  14  is disposed in a compressed state between the conductive pin  12  and the terminal  20  having its one end inserted into the blind hole  12   d  in the conductive pin  12  and the other end blocked by the protrusion  20   d  of the terminal  20  from being displaced, and in this state, the conductive pin  12  is assembled to the terminal  20 .  
         [0055]     Further, as shown in  FIG. 1 , an assembled unit of the conductive pin  12 , the terminal  20 , and the coil spring  14  is incorporated into a holder  22  appropriately, so that the terminal  20  may not be pulled out. In this state, a tip end of the plunger part  12   a  of the conductive pin  12  is projected from the holder  22 , and the conductive pin  12  is restricted from being pulled out in a projecting direction by the presence of the protruded part  12   b . The connecting part  20   a  of the terminal  20  is disposed on the bottom face of the holder  22 .  
         [0056]     In this embodiment, since the elastic contact part  20   c  of the terminal  20  is always in contact with the conductive pin  12 , it is unnecessary to incline the sliding direction in the conductive pin  12  at a certain angle with respect to the direction of movement of the contact terminal  18 , as in the conventional example. Even though the directions are in parallel with each other, reliable electrical connection can be obtained. In addition, the grooves  12   c  in the conductive pin  12  are pressed against upper faces of the guide parts  20   b  with an elastic force of the elastic contact part  20   c , and electrical connection can be obtained also in these areas.  
         [0057]     Next, a second embodiment of the invention will be described with reference to  FIGS. 4A  to  5 C. Components similar to those in the first embodiment will be designated by the same reference numerals, and repetitive explanations for those will be omitted.  
         [0058]     The second embodiment is different from the first embodiment in that, in addition to the elastic contact part  20   c  adapted to be brought into elastic contact with the conductive pin  12  from the above, a plate-shaped terminal  30  is provided with another elastic part  30   c  which is adapted to be brought into elastic contact with the conductive pin  12  from below, as shown in  FIGS. 5A  to  5 C. It is apparent that this elastic contact part  30   c  is formed in a holder  32  in such a manner that the elastic contact part  30   c  can be contacted with the conductive pin  12  from the below. Moreover, in the second embodiment, the elastic contact part  30   c  is so formed as to be brought into elastic contact with the conductive pin  12 , at the almost final stage of the pushing operation of the conductive pin  12 , as shown in  FIG. 4B .  
         [0059]     In the second embodiment, the two elastic contact parts  20   c  and  30   c  are brought into elastic contact with the conductive pin  12 , and reliable electrical connection can be obtained. Moreover, because positions where the two elastic contact parts  20   c ,  30   c  are brought into elastic contact with the conductive pin  12  are different in the sliding direction, a prying force is exerted on the conductive pin  12 , and the guide parts  20   b  of the terminal  30  are strongly pressed against both end parts of the grooves  12   c  in the conductive pin  12  to attain reliable electrical connection also in these areas. In order to pry the conductive pin  12  by these two elastic contact parts  20   c ,  30   c , it is necessary to provide a play for the sliding movement of the conductive pin  12 .  
         [0060]     Further, since the additional elastic contact part  30   c  comes in contact with the conductive pin  12  at the almost final stage of the pushing operation of the conductive pin  12 , there may be configured such that the completion of the contact operation of the contact terminal  18  is recognized through the use of the elastic contact part  30   c . The two elastic contact parts  20   c ,  30   c  may be brought into elastic contact with the conductive pin  12  in relatively opposed positions.  
         [0061]     Next, a third embodiment of the invention will be described referring to  FIGS. 6A  to  7 C. Components similar to those in the above embodiments will be designated by the same reference numerals, and repetitive explanations for those will be omitted.  
         [0062]     The third embodiment is different from the second embodiment in that, unlike the plate-shaped terminal  30  in the second embodiment, a plate-shaped terminal  40  is not provided with a pair of guide parts  20   b . Instead of the guide parts  20   b , a holder  42  is provided with a pair of guide parts  42   a  which are adapted to be engaged with the grooves  12   c  in the conductive pin  12  thereby allowing the conductive pin  12  to slide.  
         [0063]     In the third embodiment, a shape of the terminal  40  is more simplified. The holder side guide parts  42   a  can be easily formed by molding them integrally with the holder  42 , and the entire spring connector can be advantageously manufactured with light weight and at low cost.  
         [0064]     Next, a fourth embodiment of the invention will be described referring to  FIGS. 8A  to  8 C. Components similar to those in the above embodiments will be designated by the same reference numerals, and repetitive explanations for those will be omitted.  
         [0065]     In the fourth embodiment, unlike the first embodiment in which the terminal  20  is folded having the distal end directed in the forward direction of the conductive pin  12  and provided with the guide parts  20   b , a plate-shaped terminal  50  is folded into a U-shape in a sectional view perpendicular to the sliding direction of the conductive pin  12 , thus forming a pair of side parts extended inward from both sides of the connecting part  20   a . Inner edges of the side parts serve as guide parts  50   b . Although a holder is not shown in the drawing, it is apparent that the holder is formed in such a manner that the terminal  50  can be appropriately arranged and fixed thereon.  
         [0066]     The fourth embodiment having the above described structure is more suitably employed for manufacturing the spring connector provided with the guide parts  50   b  which have strong mechanical strength, as compared with the first embodiment.  
         [0067]     In the above described embodiments, the conductive pin  12  is guided in the sliding direction, by engagement of the guide parts  20   b  of the terminals  20 ,  30 ,  40  and the holder side guide parts  42   a  with the grooves  12   c  in the protruded part  12   b . However, instead of such structure, the holder may be appropriately provided with a hole through which the plunger part  12   a  and the protruded part  12   b  of the conductive pin  12  are slidable. Any structure can be employed under a condition that the conductive pin  12  can be retractably projected, and the elastic contact part of the terminal can be brought into elastic contact to attain the electrical connection.