Abstract:
A circuit board fixing structure ( 100 ) includes a base ( 3 ) and a circuit board ( 2 ). The base has a plurality of elastic claws ( 32 ) and the elastic claws vertically extend from the base. Each elastic claw includes a fastening portion ( 34 ), which forms a fastening surface ( 36 ) facing to a top surface of the base. The circuit board is encircled by the elastic claws and an upper surface of the circuit board confronts the fastening surface of the fastening portion.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to circuit board fixing structures, and more particularly to a fixing structure for a circuit board of an electronic device. 
   2. Description of Related Arts 
   As the technology advances, electronic devices such as desktop computers, laptop computers and services have played an important role in daily life. Each electronic device is provided with a circuit board (or a motherboard) fixed to a housing of the electronic device. Various ways of fixing the circuit board to the electronic device are available and cause different effects on the circuit board. 
   One of conventional methods is that a housing of an electronic device is formed with a plurality of carried pads thereon, wherein each of the carried pads has a blind hole. A circuit board has a plurality of openings corresponding to the blind holes of the carried pads and is placed on the carried pads. The circuit board is fixed to the housing of the electronic device by a plurality of coupling members such as screws inserted into the openings and the blind holes. To fix the above circuit board to the housing of the electronic device needs a screwdriver or a similar tool to screw the coupling members, which is rather troublesome and time-consuming to implement. If a force for screwing the coupling members is not proper, the circuit board may be damaged by the coupling members. Moreover, since the coupling members are often made of metallic material having electrical conductivity, a signal interference is existed with the circuit board. 
   A non-reversible method for fixing a circuit board to an electronic device is to use sticky substance. When the circuit board or some component of the electronic device has some blemish, it is difficult to remove the blemished member and the whole circuit board is broken and useless. 
   A third fixing method is shown in a circuit board fixing structure comprising a carrier for carrying a circuit board formed with a plurality of through holes, a pillar penetrating one of the through holes and a stud with a handler portion. The pillar has a first opening and a second opening corresponding to the first opening. A user holds the handler portion of the stud and let the stud penetrate the first and second openings, the stud fixes the circuit board on the carrier. However, too many components and too many steps increase the cost of the product. Furthermore, the stud of this circuit board fixing structure maybe fall off from the pillar, and as a result, a fixing effect can&#39;t be achieved 
   Hence, an improved circuit board fixing structure is desired. 
   SUMMARY OF THE INVENTION 
   Accordingly, an object of the present invention is to provide a circuit board fixing structure in which a circuit board is easily assembled and tightly fixed. 
   To achieve the above object, A circuit board fixing structure includes a base and a circuit board. The base has a plurality of elastic claws and the elastic claws vertically extend from the base. Each elastic claw includes a fastening portion, which forms a fastening surface facing to a top surface of the base. The circuit board with edges is encircled by the elastic claws and an upper surface of the circuit board confronts the fastening surface of the fastening portion. 
   Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  is a perspective, exploded view of a circuit board fixing structure according to this invention; and 
       FIG. 2  is a perspective, assembled view of the circuit board fixing structure. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 1 and 2 , an embodiment is shown. A circuit board fixing structure  100  comprises a circuit board  2  and a base  3  on which the circuit board  2  is mounted. The circuit board  2  is approximately shaped as a quadrangle taken from a top view, but the four angles thereof recess to be four cutouts  21 . The base  3  comprises four blocks  31  corresponding to the four cutouts  21  of the circuit board  2  and two pairs of elastic claws  32  locating at two opposite sides and facing to each other. The blocks  31  are used for limiting a movement of the circuit board  2  in a horizontal direction and the elastic claws  32  are used for limiting a movement of the circuit board  2  in a vertical direction. Each elastic claw  32 , extending from an upper surface (not labeled) of the base  3 , comprises a supporting bar  33  and a fastening portion  34 . The supporting bar  33  is flexible and can endure a small deflection. The fastening portion  34 , extending from a distal end of the supporting bar  33 , forms a fastening surface  36  with a downward exposure and an inclined surface  35  for guiding the circuit board  2  when the circuit board  2  is assembled onto the base  3 . Generally speaking, the claw  32  looks like an approximate “P” from a front-to-back direction. The base  3  further comprises a pair of crutch surfaces  37  lying on the upper surface thereof and having upward exposures. One baffle  38  is situated a little distance behind each of the elastic claw  32  for allowing the elastic claw  32  to deflect from an original position but not deflect so deeply. At first, the elastic claws  32  keep in its original position. When the circuit board  2  moves downward under a guidance of the inclined surfaces  35 , a force is pressed on the inclined surfaces  35  and causes a deflection of the supporting bars  33  towards the baffles  38 , accordingly, the circuit board  2  continues to go under the fastening surfaces  36 , and then, the elastic claws  32  resume to the original direction, and the circuit board  2  is sandwiched between the fastening surfaces  36  and the crutch surfaces  37  ultimately. In fact, the number of the cutouts  21  of the circuit board  2  and the number of the corresponding blocks  31  of the base  3  are not limited to be four, that is to say, we are looking forward to limit the horizontal movement of the circuit board  2 , and hence, whether the number of the blocks  31  of the base  3  is four or not is not important. For example, if a hole is existed the circuit board  2 , just only one hole corresponding to the block  31  also can retain the circuit board  2 . Moreover, the number of the edges and the number of the angles of the circuit board  2  are both not limited to be four. 
   In a second embodiment not shown in  FIGS. 1-2 , the circuit board fixing structure  100  lacks the cutouts  21  of the polygonal circuit board  2  and the corresponding blocks  31  of the base  3  of the first embodiment, and at least one elastic claw  32  is mated with each edge of the circuit board  2  for providing a limitation of a horizontal movement of the circuit board  2  and also a limitation of a vertical movement of the circuit board  2  relative to the base  3 . One elastic claw  32  of the base  3  corresponding to one edge of the circuit board  2  is the best in this embodiment, but in practice, users can reduce some elastic claws  32  for simplification. 
   In a third embodiment similar to the second embodiment, at least one elastic claw  32  is mated with each angle of the circuit board  2 , which can also achieve a limitation of a horizontal movement of the circuit board  2  and a limitation of a vertical movement of the circuit board  2 . In this embodiment, users can also reduce some elastic claws  32  for simplification. 
   In a fourth embodiment, the circuit board  2  comprises the cutouts  21  and the base  3  comprises elastic claws  32  mating with the cutouts  21 . The supporting bar  33  of the base  3  completely and fully mates with the cutout  21  for providing the limitation of a horizontal movement of the circuit board  2  and the fastening surface  36  confronts an upper surface (not labeled) of the circuit board  2  for providing the limitation of a vertical movement of the circuit board  2 . 
   In this circuit board fixing structure  100 , when a user assembles the circuit board  2  onto the base  3 , the circuit board  2  moves downward under a guidance of the inclined surfaces  35  and a force is pressed on the inclined surfaces  35  to cause a deflection of the elastic claws  32  and the circuit board  2  to be sandwiched between the fastening surfaces  36  and the crutch surfaces  37  ultimately. It makes the assembling of the circuit board  2  on the base  3  simple and it avoids the circuit board  2  from being destroyed during the assembling process. 
   While a preferred embodiment in accordance with the present invention has been shown and described, equivalent modifications and changes known to persons skilled in the art according to the spirit of the present invention are considered within the scope of the present invention as described in the appended claims.