Abstract:
A mechanism for testing a printed circuit board. The mechanism includes a holder, an expansion board and at least one fixing member. The expansion board has a first edge where a contact zone is provided. The expansion board is partially disposed in the holder with the first edge thereof exposed. The first edge of the expansion board is inserted into an expansion slot of the printed circuit board, while the contact zone provides electrical connection to the expansion slot. The fixing member fixes the expansion board in the holder.

Description:
This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 092133138 filed in Taiwan, Republic of China on Nov. 26, 2003, the entire contents of which are hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a testing mechanism, and in particular to a PCB testing mechanism with high efficiency and stability. 
   2. Description of the Related Art 
   Subsequent to manufacture, printed circuit boards (PCBs) must be tested to ensure quality thereof. In  FIG. 1 , an expansion board  16  is inserted into an expansion slot  15  of an untested PCB  11  by an operator prior to a conventional testing method. 
     FIG. 2  shows a conventional PCB testing mechanism  1 . In  FIG. 2 , a PCB  11  with expansion boards  16  assembled thereon is disposed on a bottom plate  18  of the conventional PCB testing mechanism  1 . Before testing a PCB by a conventional testing method, a driving device  14  lowers a top plate  12 , and probes  10  thereon contact a plurality of test points  111  on the PCB  11 , establishing electrical connections therebetween. Thus, whether each test circuit of the PCB  11  is conductive or not can be manually determined via an ohmmeter and shown on a monitor  19  of the PCB testing mechanism  1 . 
   However, the conventional testing method has the following disadvantages: 
   Because each fabricated PCB  11  requires testing and there are only a few expansion boards  16 , expansion boards  16  must be repeatedly manually removed from a previous PCB and then inserted in a next PCB. Thus, the conventional testing method is labor-intensive and time-consuming. Additionally, expansion boards  16  are thin, making them difficult to be hold during testing. 
   Moreover, expansion boards  16  are manually inserted into expansion slots  15  on untested PCBs  11 , but are often inserted incorrectly, causing misalignments between the contact points of the expansion boards  16  and the expansion slots  15 . Thus, the test result may be spurious and the expansion boards  16  may be damaged. 
   Furthermore, in  FIG. 1 , the engaging members  13  on either side of the expansion slot  15  must be pulled open before inserting the expansion board  16 . Operators, however, sometimes forget to pull open the engaging members  13 , causing the expansion board  16  to collide with the engaging members  13 , thus resulting in damage to the expansion board  16  or the untested PCB  11 . 
   SUMMARY OF THE INVENTION 
   Accordingly, an object of the invention is to ameliorate the disadvantages of the conventional testing method for PCBs. The present invention provides a PCB testing mechanism comprising a top plate, bottom plate, seat, holder, expansion card and at least one fixing member. The expansion board is partially disposed leaving the holder with a first edge thereof exposed. The first edge is for insertion into the expansion slot and has a contact zone for electrical connection to the expansion slot. The fixing member secures the expansion board in the holder mounted on the seat. The seat is disposed on the top plate, and the PCB is disposed on the bottom plate. The PCB testing mechanism further comprises a driving means for moving the top plate and inserting the expansion board into the relevant expansion slot. 
   The expansion board of the invention has at least one notch located at the border between the first edge and the second edge, and at least one edge of the notch is higher than the highest position of the engaging member, preventing collision between the expansion board and the engaging member when inserting the expansion board. 
   Accordingly, the expansion board can be automatically inserted by the PCB testing mechanism of the present invention, replacing the manual insertion procedure for increasing efficiency and stability and preventing operator error. Furthermore, the PCB testing mechanism of the present invention also prevents collision between the expansion board and the engaging member when inserting the expansion board, thus ameliorating the desired disadvantages of the conventional method. 
   A detailed description is given in the following embodiments with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings which are given by way of illustration only, and thus are not limitations of the present invention, and wherein: 
       FIG. 1  shows manual insertion of an expansion board into an expansion slot in a conventional testing method; 
       FIG. 2  is a schematic view of a conventional PCB testing mechanism; 
       FIG. 3  is a schematic view of a PCB testing mechanism of an embodiment of the present invention; 
       FIG. 4  shows a jig of an embodiment of the present invention disposed on a top plate thereof; 
       FIG. 5  is an stereopicture view of the jig with expansion boards assembled thereon and the top plate thereof according to an embodiment of the present invention; 
       FIG. 6  is an exploded view of the jig with expansion boards assembled thereon according to an embodiment of the present invention; 
       FIG. 7  is a front view of the expansion board according to an embodiment of the present invention; 
       FIG. 8  shows an expansion board inserted into the expansion slot according to an embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In  FIG. 3 , two expansion cards  6 , such as Dual In-line memory modules (DIMM), and probes  40  are disposed on a top plate  42  of the PCB testing mechanism  4  of an embodiment of the present invention. The number of the expansion cards  6  are not limited to two. During testing, an untested PCB  11  is disposed on a bottom plate  43  of the PCB testing mechanism  4 . A driving device  44  can make a top plate  42  move upward and downward. The driving device  44  lowers the top plate  42 , such that the expansion boards  6  are inserted into corresponding expansion slots  15  of the PCB  11 , and the probes  40  contact the test points  111  of the PCB  11 , establishing connections therebetween. Thus, whether the test circuit of the PCB  11  is conductive or not can be manually determined via an ohmmeter and shown on a monitor  45  of the PCB testing mechanism  4 . 
   Subsequent to testing, the driving device  44 , such as a motor or an air pump, raises the top plate  42 , removing the expansion boards  6  and the probes  40  from the PCB  11  simultaneously. During the above mentioned steps, the expansion boards  6  fixed on the top plate  42  are automatically rather than manually inserted and removed by the PCB testing mechanism  4 , thus increasing efficiency and reliability. 
   Placement of the expansion boards  6  on the top plate  42  through a jig  5  according to an embodiment of the invention is described in the following. 
   In  FIGS. 4 and 5 , the jig  5  holds a plurality of expansion boards  6 , but only two are given as an example in this embodiment. The top plate  42  has an opening  47  with a width D allowing holders  52  of the jig  5  to pass therethrough. A seat  51  of the jig  5 , however, is wider than the opening  47 , formed therein. The seat  51  of the jig  5  is fastened to the top plate  42  by screws  49  passing through the hole  48  thereof. 
   In  FIG. 6 , the jig  5  comprises a plurality of fixing members  53 , two holders  52  and a seat  51 . Each holder has a groove  521  to receive part of an expansion board  6 . 
   Each expansion board  6  has a first edge  61  with a contact zone  62  exposed when assembled on the holder  52 . The first edge  61  is for insertion into the expansion slot  15  of the PCB  11 , and the contact zone  62  thereof is for electrical connection to the expansion slot  15  of the PCB  11 . The expansion board  6  has a second edge  64  with a lug  63  thereon, and the second edge  64  is substantially perpendicular to the fist edge  61 . 
   Each fixing member  53  comprises a body  531  and an end  532 . The body  531  of each fixing member  53  is fixed on either side of the holder  52  by screws  54 . The end  532  is hooked, securing the lug  63  to fix the expansion board  6  in the holder  52 . 
   The seat  51  is substantially n-shaped and has a recess  511  formed in the bottom to receive the holders  52 . The holders  52  are secured on the seat  51  by the screws  55  passing through the holes  512  of the seat  51 . As shown in  FIG. 6 , the holes  512  are arranged in two parallel rows separate from a gap d 1  corresponding to the gap of the expansion slots  15  on the PCB. For example, if the gap between the expansion slots  15  on the PCB  11  is 10 cm as shown in  FIG. 4 , the gap d 1  between the rows of holes  512  is also 10 cm. 
   When installing the expansion boards  6  on the PCB  11 , the mechanism  4  of the present invention prevents collision between the expansion boards  6  and the engaging members  13  of the expansion slots  15 , even if the engaging members  13  are not pulled open. 
   In  FIG. 1 , the conventional expansion board  16  comprises notches  17  on either side. When a conventional expansion board  16  is inserted into an expansion slot  15 , the engaging members  13  clip the notches  17 , fixing the expansion board  16  thereon. In contrast, in order to prevent collisions, protruding portions below the notches  17  of each conventional expansion board  16  are cut and used in the present invention as shown in  FIG. 7 . The expansion board  6  of the present invention has notches  65  located at the border between the first edge  61  and the second edges  64  on either side. The notches  65  are substantially rectangular and range from the lugs  63  to the first edge  61 . In  FIG. 8 , the engaging members  13  are pivoted toward the expansion slot  15 , rotating between a first position  84  and a second position  85 . The second position  85  is the highest position of the engaging members  13  with respect to the expansion slot  15  during rotation, and at least one edge of the notch  65  is higher than the second position  85  of the engaging member  13 . The engaging member  13  of the present invention is able to rotate when the expansion board  6  is installed in the expansion slot  15 , thus preventing collision therebetween. 
   Accordingly, the expansion board can be automatically inserted by the PCB testing mechanism of the present invention, replacing conventional manual insertion, thus increasing efficiency and stability. The PCB testing mechanism of the present invention also prevents collision between the expansion board and the engaging member when inserting the expansion board, thus ameliorating the desired disadvantages of the conventional testing method. 
   While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.