Abstract:
A circuit board having at least one resilient leg with a catch constructed to releasably engage a shoulder of a body to releasably retain the circuit board in the body. The circuit board may be slidably inserted into a slot of the body until the catch engages the shoulder to securely and releasably retain the circuit board within the body. Desirably, the circuit board has an outwardly extending shoulder at the end of the leg opposite the catch to limit the extent of insertion of the circuit board into the body so that the catch remains generally adjacent to the shoulder. This eliminates the play or looseness in the connection between the circuit board and body by preventing the circuit board from being significantly advanced beyond the point wherein the catch engages the shoulder.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to circuit boards and more particularly, to a circuit board constructed to be releasably held in a retainer. 
     BACKGROUND OF THE INVENTION 
     Printed circuit boards are being increasingly used in a wide variety of applications. Typically, printed circuit boards are loosely and unsecurely held in place by the wires attached to them or are loosely received in or on a frame which supports them. As an alternative, to provide a more secure connection of the circuit boards to the frame, the circuit boards may be held in place by clips or bolts separate from the circuit boards and attached to the frame. Undesirably, the unsecured and loosely arranged circuit boards are difficult to connect wires to and permit the wires once connected, to become unintentionally disconnected in use. Further, securing the circuit boards to a frame or other retainer with a separate mechanical device such as a screw, clip or the like, requires an extra assembly step and thereby greatly increases the cost to manufacture and assemble the device and the circuit board into the device. 
     SUMMARY OF THE INVENTION 
     A circuit board having at least one resilient leg with a catch constructed to releasably engage a shoulder of a body to releasably retain the circuit board in the body. The circuit board may be slidably received in a slot of the body until the catch engages the shoulder to securely and releasably retain the circuit board within the body. Desirably, the circuit board has an outwardly extending shoulder at the end of the leg opposite the catch to limit the insertion of the circuit board into the body so that the catch remains generally adjacent to the shoulder. This eliminates the play or looseness in the connection between the circuit board and body by preventing the circuit board from being significantly advanced beyond the point wherein the catch engages the shoulder. 
     In one embodiment, the circuit board has a single leg formed therein by cutting a slot parallel to and slightly inboard of an outer edge of the circuit board to define an inner surface of the leg. A recess or cavity may be provided in the outer edge of the circuit board, preferably inboard of each end of the leg to define the catch and the shoulder at generally opposed ends of the leg. So formed, the leg is somewhat flexible and resilient such that upon insertion into a slot of a body having a width slightly less than the width of the circuit board measured at the outermost point of the catch, the leg will flex inwardly to permit the circuit board to be received in the slot. The slot in the body has a length less than the length of the circuit board so that when the circuit board is fully inserted into the slot, the catch is received beyond the slot to engage a shoulder of the body and retain the circuit board in the body. In another embodiment, a pair of legs are formed on the circuit board with one leg adjacent each of a pair of opposed sides of the circuit board. The legs are preferably substantially identical, but mirror images of each other to provide a catch extending generally outwardly from each of the opposed sides of the circuit board. When inserted into a slot of a body, each leg preferably flexes generally inwardly until the catch of each leg is slidably inserted beyond the slot permitting the legs to return to their unflexed position so that the catch of each leg engages an adjacent shoulder of the body. 
     Objects, features and advantages of this invention include providing a circuit board that can be securely and releasably retained within a body, is integrally formed with a mechanism to releasably retain the circuit board in the body, does not require separate mechanisms to secure the circuit board to a body, facilitates connecting plugs or wires to the circuit board, is reliable, durable, of relatively simple design and economical manufacture and assembly, and in-service, has a long useful life. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, features and advantages of this invention will be apparent from the following detailed description of the preferred embodiments and best mode, appended claims and accompanying drawings in which: 
     FIG. 1 is a perspective view of a fluid control system containing one or more circuit boards formed in accordance with the present invention; 
     FIG. 2 is an exploded perspective view of the assembly of one manifold of the fluid control system; 
     FIG. 3 is a perspective view of the assembly illustrated in FIG. 2 with a portion broken away to illustrate a leg of the circuit board; 
     FIG. 4 is a plan view of a circuit board according to the present invention; 
     FIG. 5 is an end view of the circuit board of FIG. 4; 
     FIG. 6 is a cross-sectional view taken generally along line  6 — 6  of FIG.  3  and showing a circuit board partially received in the manifold body; 
     FIG. 7 is a cross-section view similar to FIG.  6  and showing the circuit board fully received in the manifold body; 
     FIG. 8 is a side view illustrating a modified manifold adapted to receive a circuit board according to the present invention; 
     FIG. 9 is a plan view of a modified circuit board embodying the present invention; 
     FIG. 10 is a cross-sectional view similar to FIG. 7 illustrating a circuit board according to a second embodiment of the invention received within a retainer body. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring in more detail to the drawings, FIGS. 1-3 illustrate a fluid control system  18  containing circuit boards  20  in accordance with a presently preferred embodiment of the invention. The fluid control system  18  comprises a unitary manifold assembly  22  having a plurality of manifold bodies  24  with generally planer, opposed side faces  26 ,  28  and being interconnected face to face. The manifold bodies are preferably releasably connected together by cap screws extending through aligned openings in adjacent manifold bodies. Fluid passages extend through each manifold body  24  between the side faces  26 ,  28  and, in assembly of several manifold bodies  24  to form the manifold assembly  22 , the passages extend longitudinally end to end through the manifold assembly  22 . Preferably, gaskets (not shown) are disposed between adjacent manifold bodies  24  for sealing the fluid passages from each other and from the external atmosphere. 
     The control system  18  also has an input/output control module  50  with a plurality of input/output connectors  52  which either receive input signals from or send output signals to another system component. As best shown in FIGS. 2 and 3, the control module  50  has a housing  54  which receives an input/output board assembly  56 , a cover plate  58  disposed on the assembly  56  with a gasket  60  between them and a circuit board  20  slidably received in opposed channels  62 ,  63  in the housing  54 . Support pins  64  may be provided in the housing beneath the circuit board  20 . 
     The channels  62 ,  63  are preferably formed in opposed sidewalls  66 ,  68  of the housing  54 , respectively. Channel  62  of sidewall  66  has a width to closely slidably receive a corresponding edge  70  of the circuit board  20 . Channel  62  may be uniform along its length to also be complimentary to the edge  70  of the circuit board it receives in assembly. 
     The channel  63  of at least the other sidewall  68  preferably has an entrance portion  72  (FIG. 6) which is deeper than an adjacent middle portion  74  of the channel  63  to define a shoulder  76 . A downstream end  78  of the channel  63 , downstream of its middle portion  74  is also deeper than the middle portion  74  to provide a second shoulder  80  in the passage immediately downstream of the middle portion  74 . 
     As best shown in FIGS. 2-5, the circuit board  20  is a thin generally rectangular board made of any electrically insulating material suitable for use with a printed circuit thereon. The printed circuit (not shown) of each circuit board  20  is connected to a male connector  84  and a female connector  86  which plug into and receive corresponding connectors of adjacent system components. Both the male and female connectors  84 ,  86  are preferably connected to a third connector  92  mounted on the circuit board  20  into which the board assembly  56  is connected. To connect adjacent system components in series, pins  94  extending from the male connector  84  of one circuit board  20  are plugged into sockets  96  of the female connector  86  on the circuit board  20  in the adjacent system component. Thus, each system component may be readily electrically interconnected to permit the control system to be rapidly assembled and to avoid the need for the independent hard wiring of the individual circuit boards  20 . A suitable control system and manifold assembly arrangement is described in U.S. application Ser. No. 08/980,668, the disclosure of which is incorporated herein by reference in its entirety. 
     In accordance with the present invention, as best shown in FIGS. 2-7, each circuit board  20  has a blind slot  100  through the board and open to a front edge  102  of the circuit board  20 , terminating short of a rear edge  104  of the board and formed inboard of a side edge  106  between the front and rear edges  102 ,  104 . The slot  100  defines a leg  108  outboard thereof which is free at one end  110  and integral at its other end  112  with the circuit board  20 . An outer edge of the leg  108 , which is the side edge  106  of the circuit board  20 , is recessed to provide a shoulder  114  adjacent the end  112  of the leg  108  and a finger or catch  116  at the other or free end  110  of the leg  108 . Desirably, the circuit board  20  is formed of a material which is at least somewhat flexible and resilient such that the leg  108  may be flexed relative to the remainder of the circuit board  20  and will return generally to its unflexed state when unrestrained or released. Preferably, the end  117  of the slot  100  is radiused or generally arcuate to prevent a crack from propagating when the leg  108  is flexed. 
     As shown in FIGS. 2,  3 ,  6 , and  7 , to install a circuit board  20  into a manifold body  24 , the circuit board  20  is slidably received in the channels  62 ,  63  of the housing  54 . The width or distance between the middle portion  74  of the channel  63  and the bottom  119  (FIGS. 2 and 6) of the other channel  62  is less than the width or distance from the outermost portion of the catch  116  to the opposed side  70  of the circuit board  20  such that when the circuit board  20  is inserted into the housing  54 , the leg  108  is flexed generally inwardly toward the remainder or body  115  of the circuit board  20  as shown in FIG.  6 . As best shown in FIG. 7, when the circuit board  20  is fully inserted into the channels  62 ,  63  of the housing  54 , the catch  116  will be received in the downstream end  78  of channel  63  permitting the leg  108  to resiliently return to its unflexed position such that the catch  116  overlaps at least a portion of and engages the shoulder  80  of the channel  63 . Also, the shoulder  114  of the leg  108  will engage the adjacent shoulder  76  in the entrance or upstream portion  72  of the channel  63  to limit the extent of insertion of the circuit board  20  into the housing  54 . When so inserted, the circuit board  20  is trapped against lateral movement by the channels  62 ,  63  and against movement in the axial or sliding direction by the engagement of the catch  116  and shoulder  114  of the circuit board  20  with the shoulders  80 ,  76  in the housing  54 . 
     Thus, the circuit boards  20  may be easily and securely installed into their respective housing  54 . Also, each circuit board  20  may be released from its housing  54  by flexing inwardly its leg  108  until the catch  116  is free and clear of the shoulder  80  and then slidably removing the circuit board  20  from the housing  54  in the opposite direction from which it was inserted. 
     As shown in FIG. 8, the circuit board  20  may also be received in a generally vertical orientation, for example in a manifold body  24 , by simply orienting a passage  130  and associated channels  62 ′,  63 ′ in a complementary position. In all other regards, the circuit board  20  may be the same as previously described. 
     As best shown in FIGS. 9 and 10, a modified circuit board  150  may be formed having a pair of slots  151 ,  153  to define a pair of legs  152 ,  154  with one leg formed adjacent each of a pair of opposed side edges  156 ,  158  of the circuit board  150 . Each leg  152 ,  154  is preferably formed in the identical manner as the leg  108  of the circuit board  20  and are preferably mirror images of the each other so that the circuit board  150  has a pair of catches  160 ,  162 , one at a free end  164 ,  166  of each leg  152 ,  154 , and a pair of shoulders  168 ,  170 , one at the opposite end  172 ,  174  of each leg  152 ,  154 , all of which extend generally outwardly of the remainder or body  176  of the circuit board  150 . In all other regards, the circuit board  150  may be the same as the circuit board  20 . 
     To provide shoulders  178 ,  180 ,  182 ,  184  in a housing  188  engagable with both shoulders  168 ,  170  and catches  160 ,  162  of the circuit board  150 , each channel  190 ,  192  in the housing  188  is provided with front and rear cavities  194 ,  196  which define the shoulders  178 - 184  and corresponding middle portions  198 ,  200  of each channel  190 ,  192 . The distance between the opposed middle portions  198 ,  200  of channels  190 ,  192  is less than the distance between the outermost points of the catches  160 ,  162 . Thus, as the circuit board  150  is slidably received in the opposed channels  190 ,  192 , the legs  152 ,  154  are flexed generally inwardly towards the remainder or body  176  of the circuit board  150  until, as shown in FIG. 10, each catch  160 ,  162  is received in the rear cavity  196  of its corresponding channel  190 ,  192 . When the legs  152 ,  154  are received in the rear cavities  196 , the resilient nature of the legs  152 ,  154  causes them to return to their unflexed position with their catch  160 ,  162  overlapping and engaged with a corresponding shoulder  182 ,  184 . Further insertion of the circuit board  150  into the passage  186  is prevented by engagement of the circuit boards shoulders  168 ,  170  with the corresponding shoulders  178 ,  180  of the manifold body  186 . Removal of the circuit board  150  is possible by flexing inwardly each leg  152 ,  154  until each catch  160 ,  162  is free and clear of its respective shoulder  182 ,  184  and then sliding the circuit board  150  out of the housing  188  in the opposite direction it was inserted. 
     In either embodiment, the circuit board is securely and releasably retained within its housing without the aide of any external connectors such as clips or screws. Securely and releasably connecting the circuit boards within the manifold bodies greatly facilitates the interconnection of the connectors of adjacent circuit boards to electrically connect the entire manifold assembly and eliminates the vast majority of hard wiring. The time and cost to manufacture and assemble the manifold assembly or other device containing the circuit boards is greatly reduced.