Patent Publication Number: US-6666711-B2

Title: Electrical connector for a circuit board

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrical connector for a circuit board. 
     2. Description of the Related Art 
     A connector of this type is disclosed in Japan patent application Kokai No. 07-142130. 
     In this known connector, a plurality of terminals are shaped by stamping a flat metal material maintaining its flat surfaces, and provided in a housing with certain intervals so as to be parallel to each other. The plurality of terminals are similar in their shapes, and have connection sections which protrude outward from the housing and have connection surfaces at their lower rear edges. Each terminal is connected to a circuit board by soldering each connection surface to a corresponding circuit section. In addition, each terminal has a contact section at the front end of its deflectable or flexible arm in the housing, so that a flat cable is to be placed thereon when it is inserted from an open mouth of the housing. Then, the flat cable elastically contacts with the contact section by turning a movable piece over to a closed position, which is supported at the open mouth so as to freely turn over. The connection surfaces of the terminals are provided in the same plane at a time of insertion of the terminals into the housing so as to be parallel to each other with certain intervals. 
     It is desirable that the connector of this type is smaller than ever before, while it has as many terminals as possible. Since the terminals are flat-shaped, shortening the intervals between the terminals can attain high-density arrangement of the terminals and a small size of the connector. However, although a small connector can be made from the point of view of the manufacturing, the connection surfaces are so close each other that there is a problem of short-circuit by a flow of soldering paste in use. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a compact electrical connector for a circuit board without such problems as described above, thereby enabling higher density arrangement of the terminals. 
     According to the present invention, a plurality of flat-sheet terminals are held in corresponding receiving slots of a housing in a direction parallel to its sheet surface of the terminal. Each terminal has a contact section to contact with a flat cable and a connection section to connect with a corresponding circuit section of a circuit board. The plurality of terminals are arranged in a direction perpendicular to the sheet surface, being parallel to each other, while their connect sections are faced to the same side. The housing has an open mouth to insert and place the flat cable onto the connection section of the plurality of the terminals at an opposite side of the housing to the connection section, and a movable member which is movably supported at the open mouth to press the flat cable towards the contact sections. 
     In the electrical connector for a circuit board of the present invention, the connection section is formed as an end section of the terminal, protrudes outward from a bottom surface of the housing, and has a connection surface to contact with the circuit section by its surface. The connection surfaces of the adjacent terminals are provided to be staggered in the receiving direction of the terminal to the housing. 
     According to the present invention, the connection surfaces of adjacent terminals are provided to be staggered in the receiving direction of the terminal, so that each interval between the connection surfaces of adjacent terminals in the same alignment line are at least twice longer than the one between the adjacent terminals. As a result, soldering of the connection section onto the circuit board can be done without problems in spite of the high-density arrangement of the terminals. 
     According to the present invention, it is desirable that the connection surfaces of the adjacent terminals are staggered without any overlapping between the adjacent contact surfaces. Even if the connection surfaces are staggered with some overlapping between the adjacent contact surfaces, problems related to a flow of soldering paste can be lessened. However, to certainly prevent the problems related to the soldering flow, the connection surfaces are preferably staggered without any overlapping between the adjacent connection surfaces. 
     The plurality of the terminals can be comprised of different types of terminal groups, and the terminals of a first terminal group and terminals of a second terminal group can be alternately staggered in a receiving direction of the terminal. Thus, even if all the terminals of the first and second terminal groups are inserted to the same receiving position in the receiving direction, or even if the contact sections are provided at the same position, adjacent connection surfaces can be shifted with certain intervals in the receiving direction as long as the connection sections are shifted. 
     Moreover, according to the present invention, the connection section of the terminal of at least one of the terminal groups can be at least partially held in the housing, and the connection surface which is an end surface of the connection section can be designed to expose outside of the bottom surface of the housing. By doing this, the connection section which is partially held in the housing can be more firmly retained to the housing, and simultaneously the connector can be smaller in the receiving direction of the terminal for the size of the portion of the connection section held in the housing. 
     Even if the connection section is in the housing, the connector can connect with a circuit board as long as the connection surface is exposed to outside of the housing. 
     The different types of terminal groups are desirable to have the same distance between the contact section and the connection section. In this case, electrical lengths (signal transmission lengths) are the same among those terminals, so that the electrical properties and transmission time of signals are not fluctuated, especially on high-speed transmission. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG.  1 (A) is a sectional view, taken along a terminal, of a connector according to an embodiment of the present invention. 
     FIG.  1 (B) is a sectional view of the connector taken along the adjacent terminal. 
     FIG. 2 is a bottom view of part of the connector showing the connection surfaces of the terminals of FIG.  1 . 
     FIG.  3 (A) is a sectional view, taken along a terminal, of a connector according to another embodiment of the invention. 
     FIG.  3 (B) is a sectional view, taken along the adjacent terminal, of the connector of FIG.  3 (A). 
     FIG.  4 (A) is a sectional view, taken along a terminal, of a connector according to still another embodiment of the invention. 
     FIG.  4 (B) is a sectional view, taken along the adjacent terminal, of the connector of FIG.  4 (A). 
     FIG.  5 (A) is a sectional view, taken along a terminal, of a connector according to yet another embodiment of the invention. 
     FIG.  5 (B) is a sectional view, taken along the adjacent terminal, of the connector of FIG.  5 (A). 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the first embodiment of the present invention illustrated in FIGS.  1 (A) and (B), an electrical connector for a flat cable has a housing which has two types of terminals  20  and  30 . See FIG.  1 (A) for the terminal  20 , and FIG.  1 (B) for the terminal  30 . The terminals  20  and  30  are made by stamping a metal sheet or the similar method, maintaining its flat surfaces, and are arranged in a manner that two types of terminals  20  and  30  are alternately provided with certain intervals in a direction perpendicular to the paper surface of the figure. The terminals  20  and  30  are pressed into corresponding receiving slots in the housing, which are arranged parallel to the paper surface of the figure. 
     As FIG.  1 (A) shows, the first type of the terminals  20  has an upper arm (supporting arm)  21 , a lower arm  22  and a connection section  23  from which the upper arm  21  and the lower arm  22  extend forwardly along the inner surfaces of an upper wall  13  and a lower wall  14  of the corresponding receiving slot  11 . The connection section  23  protrudes rearwardly from the lower wall  14  or rightwardly in the figure. The upper arm  21  has engaging protrusions  21 A and  21 B at an upper edge of its base area, which prevent sliding out of the terminal from the housing by engaging the inner surface of the upper wall  13  of the housing  10  when the terminal  20  is inserted from right side to a predetermined position. The upper arm  21 , which is relatively rigid to a deflection in a paper surface of the figure, is more rigid than the lower arm  22 . An end section  24  of the upper arm  21  is enlarged in its height direction, and its upper edge  24 A is positioned higher (outward) than a lower (inner) surface of the upper wall  13  of the housing  10 . Also, a transitional section from the upper edge  24 A to an intermediate portion of the upper arm  21  has a shoulder  24 B with gentle slope. 
     The end section  24  of the upper arm  21  has a semi-circular bearing section  25  at its lower edge. The bearing section  25  rotatably supports a movable piece, as described below, and work as a bearing. Since the upper edge  24 A is upward from the lower surface of the upper wall  13  of the housing  10  and extends to proximity of the upper surface of the housing, the distance between the bottom of the bearing section  25  and the upper edge  24 A is so large that the area around this section is strong. 
     The lower arm  22  of the terminal  20  is narrower than the upper arm  21 , and is deflectable in a plane parallel to the paper surface of the figure. A lower edge of the lower arm  22 , especially a portion close to its end has an upward inclination  22 A. In addition, the lower arm  22  has a contact section  26  at its free end, which protrudes towards the bearing section  25  of the upper arm  21 . A base section  22 B of the lower arm  22  is pressed into the inner surface of the lower wall  14  of the housing  10 , so that the engaging protrusions  21 A and  21 B of the upper arm  21  are pressed towards the upper wall  13  by a reaction force from the lower wall  14 . Accordingly, it is preferable that the engaging protrusions  21 A and  21 B are located above the base section  22 B, and it is further preferable that the engaging protrusions  21 A and  21 B are directly above the base section  22 B without being offset from the base section  22 B. 
     The connection section  23  of the terminal extends rearwardly from the base section  22 B of the lower arm  22  to outside of the housing. A lower edge surface of the connection section  23  protrudes slightly downward from a bottom surface of the housing  10  and forms a connection surface  23 A. When the housing  10  is put on a predetermined position of a circuit board (not illustrated), the connection surface  23 A is to be placed onto a corresponding circuit section of a circuit board, and connected to the circuit section by soldering. The second type of the terminal  30  also has an upper arm  31 , a lower arm  32  and a connection section  33 , which are similar to the first type of the terminal  20 , but are slightly different in their forms. 
     The upper arm  31  also has a bearing section  35  at its end, but it is not semi-circular groove, like the bearing section  25  of the first type of terminal  20 , but just has a round end. In addition, two engaging protrusions  31 A and  31 B of the upper arm  31  are provided further inward of the housing, that is, leftward in the figure, in comparison with the upper arm  21  of the terminal  20 , due to the relationship with the lower arm  32  as described below. The lower arm  32 , which is deflectable, is made longer than the lower arm  22  of the terminal  20 , and has a contact section  36  at its free end, which protrudes upward. A base section  32 B of the lower arm  32  is provided leftward from the base section  22 B of the terminal  20 , so that the engaging protrusions  31 A and  31 B are arranged in a corresponding range to the base section  32  in a lateral direction in the figure. 
     A connection section  33  of the terminal  30  is provided in the housing  10 . The lower wall of the housing, which is also a lower edge of the receiving slot  12 , has a cutting  14 A at its right end, and the connection section  33  is placed within a range of the cutting  14 A. Similar to the terminal  20 , a lower edge of the connection section  33  forms a contact section  33 A, and the connection section  33 A slightly protrudes downward from the bottom surface  14 B (lower surface of the lower wall  14 ) of the housing  10 . 
     The connection section  33  is shaped with a notch  33 B which inclines at an acute angle to the connection surface  33 A. Since the connection section  33  of the terminal  30  is in a slit-shaped receiving slot which is parallel to the sheet surface of the figure, a flux of soldering paste tends to flow into a space between the connection section  33  and the receiving slot  12  due to capillary phenomenon at a time of soldering at the connection surface  33 A. It is not desirable that the flux reaches the contact section  36 . To solve this problem, as FIG.  1 (B) shows, the notch  33 B is inclined with an acute angle in rightward in the figure so as to be away from the contact section  36 . Accordingly, even if the flux elevates, it would not reach the contact section. Since the connection section  33  is in the housing  10 , it is difficult to see the elevated flux but, even in this case, soldering can be done without concern because the elevated flux has no influence upon the contact section. 
     Consequently, the connection surfaces  23 A and  33 A of the terminals  20  and  30 , which are alternately provided in arranging direction, are staggered in a connection surface plane as shown in FIG.  2 . Thus, the connection surfaces  23 A and  33 A are arranged corresponding to the circuit sections P which are similarly staggered on the circuit board. 
     In the connector illustrated in FIGS.  1 (A) and (B), the different types of terminals  20  and  30  are alternately provided, and the contact sections  26  and  36  are in different positions in the height direction in the figure so that they are arranged in a zigzag fashion in its plan view. This is preferable to contact with a flat cable in broad area. However, in the case of a high-speed transmission, it is not preferable if the distance between the contact section  26  and the connection section  23  of the terminal  20  is different from the one between the contact section  36  and the connection section  33  of the terminal  30 , because the difference of electrical lengths (signal transmission lengths) causes degradation of the electrical characteristics and fluctuation of the transmission time. In the example illustrated in the figure, distances between the contact section and the connection section are designed not to be different between the two types of the terminals, by shifting the contact section  26  or  36  for a distance equivalent to the shifted length between the connection sections  23  and  33 . 
     As described above, the housing  10  has slit-shaped receiving slots  11  and  12  to insert the terminals  20  and  30  which are made from a metal sheet maintaining its sheet surfaces. The receiving slots are alternately provided as many as the number of each type of the terminals, being parallel to the sheet surface of the figure. The upper wall  13  and the lower wall  14  of the housing  10 , which form the upper and the lower edges of the receiving slots  11  and  12 , define inserting positions of the terminals  20  and  30 . The base sections  22 B and  32 B of the lower arms  22  and  32  contact with the inner surface of the lower wall  14  and, as described above, the engaging protrusions  21 A,  21 B;  31 A,  31 B of the upper arms  21  and  31  secure the positions of the terminals and prevent sliding out of the terminals  20  and  30  from the housing  10  by engaging the upper wall of the housing  10 . 
     The housing  10  has at least one cable slot  15  to insert a flat cable C into the housing  10  from left side. The cable slots  15  are provided so as to be communicatively connected across the plurality of the receiving slots  1  and  12  between the upper and lower walls in a range substantially equal to the width of the flat cable C (dimension in a direction perpendicular to the sheet surface of the figure), that is, the width of arrangement of the both types of terminals. 
     Also, the housing  10  has an open mouth  16  which is open above the cable slots  11  and  12  up to the front end of the upper wall  13  of the housing  10  and extends downwardly to the cable slot  15 . 
     The open mouth  16  of the housing  10  has a movable member  40  made from an insulating material. The movable member  40  is supported by the bearing sections  25  and  35  for rotation between a closed position, which is illustrated in FIGS.  1 (A) and (B), and an open position where the movable member  40  is turned over for a predetermined angle from the closed position in a direction of an arrow A in the figures. The movable member  40  has an operating section  41  at its front and a plurality of slots  42  and  43  at the rear end. The operating section  41  is used to give a rotational force to the movable member  40 . The slots  42  and  43  receive the front end section of the upper arms  21  and  31  of the terminals  20  and  30  and have a slit-shape which corresponds to the shape of each upper arm  21 ;  31 . The slots  42  and  43  are alternately provided so as to form a comb-like shape. A shaft portion  44  is provided in the slot  42  and is rotatably supported by the bearing section  25 , while a straight section  45  is provided so as to contact with the bearing section  35  for rotation. 
     The connector of the present invention is used in the following manner: 
     (1) First, place the connector to a predetermined position on a circuit board (not illustrated), and connect the connection sections  23  and  33  of the terminals  20  and  30  to each corresponding circuit section P of the circuit board at connection surfaces  23 A and  33 A. In this case, as apparent from FIG. 2, since adjacent connection surfaces  23 A and  33 A of two types of terminals  20  and  30  are shifted in the vertical direction, soldering can be done with the interval of adjacent connection surfaces  23 A or  33 A of the same type of the terminals. That is, soldering can be done with the distance twice as long as the interval between the adjacent different types of terminals  20  and  30 . Thus, even when the terminals  20  and  30  are arranged in high density, there is no concern of a short-circuit due to the flow of soldering paste. 
     (2) Then, turn the movable member  40  in the direction A to the open position. 
     (3) When the movable member  40  is at the open position, the open mouth  16  is opened widely at the left-hand side. Accordingly, it is easy to see an entrance (inserting space) of the cable slot  15  from the inserting side of a flat cable C. At this point, insert the flat cable C to the cable slot  15 , with the connection side facing down, until the front end of the cable C contacts with the deepest wall of the cable slot  15 . 
     (4) Once the cable is inserted to the predetermined position, turn the movable member  40  in the opposite direction to the arrow A over to the closed position as illustrated in FIGS.  1 (A) and (B). Consequently, the movable member  40  presses the flat cable C at its pressuring section  46  towards the contact sections  26  and  36  of the terminals  20  and  30  to connect them electrically. 
     The present invention is not limited to the embodiment illustrated in FIG. 1 and, for an example, the connection sections  22  and  33  of the two types of terminals  20  and  30  can be provided in different positions from FIG. 1 in the receiving direction of the terminals. In FIGS.  3 (A) and (B), both the connection sections  23  and  33  of the terminals  20  and  30  are provided inside the housing  10 . The lower walls  14  of the receiving slots  11  and  12  of the housing  10  have openings  14 A, like the one illustrated in FIG.  1 (B). Also in this case, the connection surface  33 A is located at a shifted position in comparison with the connection surface  23 A in the receiving direction of the terminal, so that the opening  14 A for the connection surface  33 A is provided also in a shifted position corresponding to the shift between connection sections  23  and  33 . By doing this, when the connection sections  23  and  33  are put into the housing, the connection sections  23  and  33  can be securely retained and firmly supported by the side faces of the receiving slots  11  and  12 , and simultaneously the size of the connector can be made smaller in the receiving direction of the terminal. 
     The above-described effects are partially attained even if the whole connection sections are put into the housing. For an example, in FIG.  4 (A), the terminal  20  is the same as the terminal  20  of FIG.  1 (A), while a part of the connection section  33  of the other terminal  30  is held in the housing  10  while the rest of the connection section  33  protrude outside the housing  10 , as illustrated in FIG.  4 (B). By doing this, the connection section  33  is retained with a retaining power lower than that of FIG.  1 (B) but still retained firmly, and it is easier to check the soldering for the portion of the connection section which is outside of the housing. Also, the position of the connection sections can be precisely controlled. 
     In FIGS.  5 (A) and (B), the connect sections  23  and  33  of the both terminals  20  and  30  are provided outside of the housing  10 . In this case, the size of the connector is larger than the above examples in the receiving direction of the terminals, and the connection sections are not firmly supported by the receiving slots, but it is much easier to check the soldering. This is suitable where there is an enough space around the connector on the circuit board. 
     Furthermore, the present invention is not limited to the case of two types of the terminals, and can have more than tree types of terminals. Where the connector has only one type of the terminal, this can be coped by shifting the receiving positions of the adjacent terminals inside the housing. In either case, there is no problem as long as the connection surfaces of the adjacent terminals are staggered in the receiving direction with or without overlapping the adjacent connection surfaces. Also, the present invention does not limit the form of the movable member  40 . That is, the movable member  40  can be the rotationally movable type, like the one illustrated in the figures, or can be a linearly movable type. 
     According to the present invention, the connection surfaces, which are formed at the ends of the sheet-type terminals, are staggered in the receiving direction of the terminals into the housing, so that the intervals between the adjacent contact surfaces in a direction perpendicular to a sheet surface of the figures is wide enough to prevent problems related to connection of the connector with the circuit board by soldering where a plurality of the terminals are arranged with high density; therefore the smaller connector can be made by arranging the terminals in high density.