Patent Publication Number: US-6663444-B2

Title: Electrical connector with highly compliant terminals

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to conductive terminals in electrical connectors, and particularly to terminals shaped to have improved compliance and thereby reduce stress concentration when the terminals are mated with corresponding terminals of a complementary connector. 
     2. Related Art 
     Handheld computers, including personal digital assistants (PDAs) and palm-sized computers, use peripheral or accessory devices to enhance their capabilities and functions. Accessory devices for handheld computers include communication cradles, docking stations, plug assemblies, battery chargers, and modems. Generally, accessory devices are connected with the handheld computers via electrical connector assemblies. 
     Conventionally, a plug connector is mounted on a handheld computer. An accessory device has a cable connector for mating with the plug connector, thereby achieving electrical connection between the handheld computer and the accessory device. Modern handheld computers are particularly slim, therefore the plug connector can only have a small form factor. Accordingly, conductive terminals of the plug connector are small. This results in high stress concentration in the terminals when the plug connector is mated with the cable connector. High stress concentration accelerates fatigue and increases the risk of breakage of the terminals. Conventional terminals of handheld computer plug connectors do not have good compliance. Therefore the terminals sustain unduly high stress concentration. 
     Accordingly, improved conductive terminals for plug connectors of handheld computers are desired. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide an electrical plug connector used in a handheld electronic device, wherein conductive terminals of the plug connector each have a configuration that a normal force generated by the conductive terminals of the connector can be distributed over a long length of the terminals whereby stress concentration of the terminals can be lessened. Therefore, a life of use of the conductive terminals and accordingly the plug connector can be extended. 
     A further object of the present invention is to provide a plug connector for a handheld electronic device, wherein the conductive terminals of the connector are compliant so that stress concentration of the terminals caused by the normal force of the terminals for effectively engaging with terminals of a complementary connector can be further reduced. 
     In order to accomplish the above objects, an electrical connector includes a dielectric housing which has a front mating end, a rear mounting end opposite the mating end, two lateral ends between the mating and mounting ends, and a plurality of terminal passageways defined between the mating and mounting ends. A plurality of Ω-shaped conductive terminals are mounted in the passageways on the housing, particularly, each of the terminals comprises a solder tail located about the mounting end of the housing adapted for soldering to a printed circuit board of the handheld electronic device, a retention portion located in front of the tail portion and secured to the housing, a first arced portion extending forwardly and upwardly from the retention portion, a horizontal beam extending forwardly from the first arced portion, a second arced portion extending forwardly and upwards from a front end of the horizontal beam and a contacting portion extending rearwards from a free end of the second arced portion into a front end portion of a corresponding passageways, said contacting portion being adapted for engaging with a terminal of a complementary connector. 
     In mating with the cable connector, terminals of the cable connector are inserted into upper portions the passageways from the mating end to depress against and engage with the contact portions of the conductive terminals. The terminals generate a normal force by deforming the looped spring portions and the second arcuate portions to effectively and reliable engage with the complementary terminals. As the stress induced by the normal force are distributed over the two arced portions, stress concentration happened in the conventional connector can be improved. Furthermore, since the terminals are secured to the housing only with the retention portions, the terminals can have a good compliance to have a better engaging characteristic with the complementary terminals. 
     Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with its objects and the advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: 
     FIG. 1 is an exploded perspective view of an electrical plug connector in accordance with the present invention; 
     FIG. 2 is a perspective view of a conductive terminal of the connector of FIG. 1; 
     FIG. 3 is an assembled view of FIG. 1; 
     FIG. 4 is a top plan view of FIG. 3; 
     FIG. 5 is an enlarged cross-sectional view taken alone ling V—V of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in detail, FIG. 1 shows an electrical plug connector  1  in accordance with the present invention. The plug connector  1  is designed for mounting on a printed circuit board (PCB) of a handheld electronic device (not shown) such as a handheld computer or a personal digital assistant (PDA). The plug connector  1  includes an elongated one-piece dielectric housing  10  and a plurality of terminals  30 . 
     The housing  10  is molded from plastic material or other suitable material. The housing  10  comprises a base  101 , a front mating end  14 , a rear mounting end  24  opposite the mating end  14 , and a pair of opposite lateral ends  16  connecting the mating and mounting ends  14 ,  24 . Two locating posts  225  extend forwardly from opposite extremities of the mating end  14 , for aligning the plug connector  1  with a complementary cable connector (not shown) prior to mating. A semicircular protrusion  18  is formed at each of the lateral ends  16 , for fitting into corresponding recesses defined in a chassis of the handheld electronic device. A shoulder  22  is formed at and parallel to the mating end  14 . A terminal accommodating block  25  is formed between the walls  20  and the shoulder  22 . The block  25  has a stepped top face  251 , thereby defining a recess  252  above a part of the top face  251  that is nearest the mounting end  24 . A plurality of parallel terminal passageways  29  is defined in the block  25 . Bottom portions of the passageways  29  span between the mounting end  24  and the mating end  14 . A plurality of partitions  27  is thus each formed in the block  25 , each partition separating two adjacent passageways  29 . A pair of slots  243  is defined in bottommost portions of opposite faces of each partition  27 , adjacent the mounting end  24 . A pair of spaced and parallel walls  20  extends between the mating end  14  and the mounting end  24 , on opposite sides of the block  25  respectively. A cavity  19  is defined between one lateral end  16  and its proximate the wall  20 . 
     FIG. 2 shows an omega (Ω) shaped terminal  30 , which is stamped and formed from a sheet of conductive material. Each terminal  30  includes a retention portion  37 , for being interferentially fixed in two corresponding slots  243  of the block  25 . The retention portion  37  comprises a pair of front barbs  371 , and a pair of rear barbs  373 . A soldering tail  375  extends rearwardly from the retention portion  37 , for being soldered to the PCB of the handheld electronic device. A looped spring portion  31  extends upwardly and generally forwardly from the retention portion  37 , for protruding into the recess  252  of the block  25 . A vertical beam  35  depends from a bottom front extremity of the looped spring portion  31 . A horizontal beam  33  extends perpendicularly forwardly from a bottom extremity  36  of the vertical beam  35 . A small arcuate portion  331  extends forwardly and then progressively upwardly and then progressively rearwardly from a front extremity of the horizontal beam  33 . A contact portion  333  extends rearwardly and slightly downwardly from a free end of the arcuate portion  331 . 
     Referring particularly to FIGS. 3-5, the terminals  30  are mounted into the housing  10 . The retention portions  37  are interferentially fixed in the slots  243 . The looped spring portions  31  are received in the passageways  29 . Upper sections of the looped spring portions  31  project into the recess  252  of the housing  10 . The tail portions  375  protrude rearwardly from the mounting end  24 , for being soldered to the PCB (not shown) of the handheld electronic device. The horizontal beams  33  are located in the bottom portions of the passageways  29 . The small arcuate portions  331  protrude out from the mating end  14  between the locating posts  225 . The contact portions  333  extend from the arcurate portions  331  back into the passageways  29 . The contact portions  333  are spaced from the housing  10 , to facilitate the contact portions  333  contacting with terminals of the cable connector. 
     When the plug connector  1  is mated with the complementary cable connector (not shown), terminals of the cable connector are inserted into the passageways  29  at the mating end  14  of the plug connector  1 . The terminals of the cable connector are inserted above the contact portions  333 , and elastically depress and engage with the contact portions  333 . The terminals  30  generate a normal force by elastically deforming the looped spring and arcurate portions  31 ,  331 , thereby effectively and reliably engaging with the terminals of the cable connector. Because the stress induced by the normal force is distributed throughout the looped spring and the arcurate portions  31 ,  331 , stress concentration in the terminals  30  is minimized. Furthermore, the terminals  30  are fixed to the housing  10  only at the retention portions  37 . Therefore the terminals  30  have excellent compliance, and provide superior engaging characteristics with the terminals of the cable connector. 
     It will be understood that the present invention may be embodied in other specific forms without departing from its spirit or central characteristics. The present examples and embodiment are therefore to be considered in all respects as illustrative and not restrictive, and the present invention is not to be limited to the details given herein.