Abstract:
An electrical connector which includes an insulative body which has a leg portion and a top portion which extends generally perpendicularly from the leg second portion. A conductive contact which includes a retention section and a resilient section is also included in the electrical connector. The contact is fixed to the top section and the resilient section extends along the leg section. The connector may be interposed between a electrical device and a printed circuit board.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 09/001,971, filed on Dec. 31, 1997, and claims the benefit of U.S. Provisional Patent Application No. 60/042,360, filed on Mar. 26, 1997, both of which are herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to electrical connectors and particularly to printed circuit board connectors. 
     2. Brief Description of Prior Developments 
     Electrical connectors for connecting small panel-like electrical devices, such as circuit boards or liquid crystal displays (LCD) to another circuit board are known. One such connector employs an insulative body having a slot for receiving an LCD module. A linear array of connector terminals are mounted on the body. The spring portions disposed at one end of the terminals are located along the slot to engage circuit contact pads on the LCD. The other ends of the terminals are wrapped about the connector body and extend in a fixed position along a bottom edge of the connector body to form bottom contacts. Because the bottom contacts have no compliance, it is necessary to utilize a sheet of elastomeric material between the bottom of the connector body and the circuit board. The elastomeric body is provided with appropriate conductive traces to electrically connect the bottom contacts with appropriate contacts on the printed circuit board. The connector is held compressed against the elastomeric material by a compressive force, typically generated by the portion of the housing in which the LCD is mounted. It is common to apply an adhesive to hold the connector secure onto the LCD. The use of conductive elastomers and adhesives adversely affects the ease and cost of manufacturing devices, such as portable hand held electronic devices that have visual displays, such as cellular telephones. 
     SUMMARY OF THE INVENTION 
     The electrical connector of the present invention includes an insulative body comprising a first portion and a second portion extending generally perpendicularly from the first second portion. The connector also includes a conductive means comprising a retention section and a resilient section. The conductive means is retained by the second portion of the insulative body and the resilient section extending adjacent the first portion of the insulative body. The connector may be interposed between a planar electrical device and a printed circuit board. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The electrical connector of the present invention is further described with reference to the accompanying drawings in which: 
     FIG. 1 is a front elevational view of a connector embodying the invention; 
     FIG. 2 is a side elevational view of the connector shown in FIG. 1; 
     FIG. 3 is a back elevational view of the connector shown in FIG. 1; 
     FIG. 4 is a bottom view of the connector shown in FIG. 1; 
     FIG. 5 is a cross-sectional view taken along line AA of FIG. 3; 
     FIG. 6 is an enlarged view of area B of FIG. 1; 
     FIG. 7 is an enlarged view of area C of FIG. 4; 
     FIGS. 8 a - 8   f  are sequential illustrations of manufacturing and installation steps related to the connector of FIG. 1; and 
     FIGS. 9 a  and  9   b  show positions of the connector of FIG. 1 during application and use. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention will be described in the context of a connector specifically adapted for electrically connecting planar electrical devices, such as LCD&#39;s, to another circuit board. However, the invention is believed to have applicability in other connectors. 
     FIG. 1 shows a connector  10  having a body  12  formed of a molded polymeric insulating material. The body  12  includes a vertically extending leg portion  14  and a generally horizontally extending top portion  16 . The connector also includes a plurality of suitable conductive metal terminals  18 , preferably formed by stamping. 
     Each terminal  18  includes a cantilevered spring contact portion  20  for engaging an electrical device, as will later be described. Terminals  18  further include a retention portion  22  (FIG.  5 ), where the terminal  18  is retained in the body  12 . Each terminal further includes a downwardly extending resilient beam portion  24  extending along the rear of the body  12 . As will later be described, the portion  24  generally forms a Euler&#39;s Beam structure. At the bottom of each terminal  18  is a PCB contact portion  26  for engaging contact pads on a printed circuit board, as will later be explained. As can be seen in FIG. 5, the PCB contact section  26  is formed as a curved surface having an outside radius that contacts the printed circuit board. Adjacent the contact portion  26  is an opposed pair of retention ears  28  and  30  (FIG.  7 ), the upper portions  29  and  31  (FIG. 6) of which are bent inwardly to form radiused surfaces, such as surface  32  (FIG. 8 d ). 
     As shown in FIGS. 3,  4  and  8   a-f,  grooves  34  are formed in the back of the housing  12  for receiving the portions  24  of beams  18 . Additionally, undercut portions  36  are formed in opposing relationship in each groove  34 . The undercut portions  36  form shoulder surfaces  38  that are designed to engage the surfaces  32  of terminal  18 , as will later be described. 
     In FIG. 8 a,  the connector  10  is shown in a intermediate stage of manufacture. In this stage, an array of terminals  18  in coplanar, side-by-side relationship may be formed by stamping from terminal sheet stock. As shown in the figure, the ends of the terminals  18  have been preliminarily bent to form the contact portion  21  of the cantilevered spring arm  20  and the printed circuit board contact portion  26 . The connector body  12  is preferably formed by overmolding or insert molding the connector body  12  onto the array of terminals  18 , so that the terminals are securely held in the body  12 . 
     Referring to FIG. 8 b,  the cantilevered spring portion  20  has been formed by bending. Also, the beam portion  24  is formed by applying a force in the direction of arrow F 1  at or near the tip of the section  24  to bend the section  24  about a bend radius formed generally in the area of region  39 . Eventually, the beam portion  24  is bent toward the full line portion shown in FIG. 8 c.  At this time, force F 1  is maintained on the end of the beam  24 . At the same time, a force F 2  is applied to the mid-section of the beam to extend the length of the beam to position the tip section  26  toward the dotted line position shown in FIGS. 8 c  and  8   d.  At this time, the surface  32  of each of the ears  28 ,  30  is positioned in general alignment with the shoulder surfaces  38 . After the force F 2  is removed, the beam retracts so that the surfaces  32  of the ears  28 ,  30  are retained against the shoulder surfaces  38 . In this manner, the portion  26  is located and a desired amount of preload is imparted on it. 
     The terminal section  24  operates generally in the manner of a Euler&#39;s buckling beam whereby, as the beam is buckled, it changes length. That is, when a force the direction of arrow F 2  is applied, the beam lengthens in the direction of arrow L 1 . Conversely, when the force F 2  is removed, the spring force in the beam returns the beam to its original shape, thereby shortening the length of the beam and raising the contact section  26  toward the connector body  12 . 
     FIG. 8 e  shows the connector  10  substantially in a rest position, with the printed circuit board contact portion  26  extending beneath the housing. FIG. 8 f  shows the connector in mated condition, wherein a force in the direction of arrow F 3  holds the connector  10  against the substrate  40  causing the beam  24  to be buckled. The resulting deflection generates a normal force pressing contact portion  26  against PCB  40 . In addition, a force applied in the direction of arrow F 4  to the LCD  42  causes the contact section  20  to deflect, thereby generating a normal force pressing contact portion  21  against LCD  42 . 
     As shown in FIG. 9 a,  in a typical application, a frame  44  is provided to support the LCD  42  and the connector  10 . In this arrangement, the LCD  42  is supported on portions (not shown) of the frame  44  and the connector  10  is inserted into the frame  44  by pushing the leg  14  of the connector through an aperture or recess in the frame  44 . To accomplish this, a force in the direction of arrow F 6  is placed on the connector  10  to insert the connector into the frame. In doing so, a retention tang  46  formed on the back of the connector body  12  is forced past the retention edge  48  of the opening. In this condition, the cantilevered beam contact  20  and the buckling beam  24  are deflected to a maximum extent, as the bottom edge of the connector is pressed against the surface of the printed circuit board  40 . This figure also illustrates the action of the connector if, after assembly, a downward force is applied to the connector/LCD assembly, as by pressing downwardly on the LCD. An advantage of this construction is that the electrical connection at the level of contact portion  26  is maintained, even though a relatively high compressive force is repeatedly applied to connector  10 . FIG. 9 b  shows the final mated position of the connector  10  wherein the retention tang  46  is retained against the surface  48  and the connector  10  has moved upward slightly away from the PCB  40 , as a result of the spring force in beam  24 . 
     It is to be further noted that the printed circuit board contact portion  26  undergoes a wiping and rolling action during this operation, to effect proper electrical connection with contact pads on PCB  40 . This occurs as a result of the imposition of a vertical force on the beam section  24 , which causes the section  26  to move along the surface of PCB  40  in the direction of arrow F 5  (FIG. 9 a ). As this occurs, the contact portion  26  also rotates about a contact point between radius  32  and shoulder surface  38 . 
     The connector disclosed has many advantages. The Euler&#39;s buckling beam arrangement provides a relatively long spring travel using only a small area of the footprint of the connector. It also provides simplified locating and pre-loading of the contact portion  26 . It further allows a contact wiping and cleaning action, thereby providing good contact. Further, this approach eliminates the need for conductive elastomeric members between the connector and the PCB. 
     While the present invention has been described in connection with the preferred embodiments of the various figures, it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims.