Abstract:
Disclosed is a device for insertion and removal of a circuit board into a mating connector positioned within a housing, the device having a first end for pivotal engagement with the circuit board and adapted to mate with a front surface of the housing when the circuit board to which the device is pivotally engaged begins to engage the connector, and a second end disposed longitudinally from the first end and adapted with a latch for releasably mating with a protrusion on the board such that when the board is engaged with the connector the second end becomes releasably mated to the protrusion thereby latching the board to the connector.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to circuit board latches and more particularly to a device and method for circuit board insertion and removal.  
         DESCRIPTION OF RELATED ART  
         [0002]    It is now common practice to insert printed wiring boards (PWBs) and other electronic devices into housings where contacts on the PWB are inserted into a connector attached to the housing. Typically, such housings have a plurality of slots into which PWBs may be positioned, either vertically or horizontally. Often a considerable amount of force is necessary to push the PWB contacts into the mating connector on the housing to insure proper electrical contact is made and maintained throughout the time the PWB remains in the housing. Accordingly, it is often useful to fasten the PWBs into the housing in a semi-permanent manner, so that, regardless of the vibration or other operational characteristics of the housing, the PWBs remain firmly in place.  
           [0003]    Often such latching of the boards is accomplished by a screw or other locking device which requires some degree of skill on the part of the user. Moreover, the semi-permanent latching often requires a tool and/or an appreciable amount of time to accomplish both the locking and unlocking operations.  
           [0004]    Alternatively, some latching mechanisms rely on friction or gravity to maintain the PWBs into the back plane connector. However, particularly in some environments, such a technique provides less than ideal retention of the PWB. In addition, many presently available solutions require a large amount of board space in order to function properly and the user generally needs to be familiar with their operation in order to properly latch or unlatch a PWB.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    An embodiment of the present invention provides a device for insertion and removal of a circuit board into a mating connector positioned within a housing, the device comprising a first end for pivotal engagement with the circuit board and adapted to mate with a front surface of the housing when the circuit board to which the device is pivotally engaged begins to engage the connector, and a second end disposed longitudinally from the first end and adapted with a latch for releasably mating with a protrusion on the circuit board such that when the board is engaged with the connector the second end becomes releasably mated to the protrusion thereby latching the board to the connector.  
           [0006]    Another embodiment of the present invention provides a method of locking a printed wiring board into a connector, the connector mounted to a housing, the housing having at least one guide for positioning the board with respect to the connector, the method comprising placing a board within the guide in a direction such that the board will, upon the application of insertion force thereupon, move into mated relationship with the connector, applying the insertion force to the board to move the board toward the connector until a first end of a device which is pivotally mounted to the board engages with an edge of the housing, rotating the device so that a longitudinal portion of the device engages on a portion of the board, continuing to apply force to the device so as to move the board and the connector into the mated relationship, and retaining the device in an engaged position on the portion of the board, even after the external insertion force has been removed, the engaged position preventing the board from becoming disconnected from the connector at least in part by the first and of the device engaging the edge of the housing.  
           [0007]    An embodiment of the present invention provides a device for locking a printed wiring board (PWB) into a connector, the connector mounted to a housing, the housing having at least one guide for positioning the board with respect to the connector, the device comprising means for applying an external insertion force to the PWB to move the PWB toward the connector along the guide, the means having a first end pivotally attached to the PWB board, the first end having a portion for engaging with a portion of the housing, means for contacting a front edge of the PWB along a longitudinal portion of the device, and means for maintaining at least a portion of the insertion force after the external insertion force has been removed.  
           [0008]    An embodiment of the present invention provides a latching device for use with housing accepting a plurality of electronic boards into mating relationship with a plurality of connectors affixed to the housing, the housing having at least one locking portion for mating with the latching device pivotally mounted on at least one electronic board, the latching device comprising means for applying an external insertion force to an electronic board of the plurality of electronic boards to move the electronic board toward a corresponding connector of the plurality of connectors along a guide, the means having a first end pivotally attached to the board, the first end having a portion for engaging with a portion of the housing, means for contacting a front edge of the PWB along a longitudinal portion of the device, and means for maintaining at least a portion of the insertion force after the external insertion force has been removed.  
           [0009]    Another embodiment of the present invention provides a latching device for use with an electronic circuit board mating with a connector within a housing, the housing having at least one locking portion for mating with the latching device pivotally mounted to the board, the latching device comprising means for applying an external insertion force to the electronic circuit board to move the electronic circuit board toward the connector along a guide, the means having a first end pivotally attached to the electronic circuit board, the first end having a portion for engaging with a portion of the housing, means for contacting a front edge of the electronic circuit board along a longitudinal portion of the device, means for maintaining at least a portion of the insertion force after the external insertion force has been removed, and wherein the board contains a protrusion for operation in conjunction with the maintaining means.  
           [0010]    An embodiment of the present invention provides a printed wiring board (PWB) adapted for latching into a mated relationship with a housing mounted connector, the PWB comprising a protrusion for releasable accepting a latching mechanism, the latching mechanism operable, in conjunction with the protrusion, and with an outer portion of the housing, for maintaining positive force between the PWB and the connector after externally applied insertion force has been removed.  
           [0011]    An embodiment of the present invention provides a device for aiding in latching an electronic circuit board in a mated relationship with an electrical connector, the connector located at a back end of a housing, the device comprising a first end for engaging a front surface of the housing, means for pivoting the first end around an outer corner of a circuit board to be latched, a second end disposed laterally from the first end the second end comprising a latch mechanism for releasably latching to a pin mounted on the board, and a body extending between the ends, the body having upper and lower portions separated by a distance to allow at least a portion of the board to fit between the portions when the latch mechanism is latched to the pin. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 shows an isometric view of one embodiment of a circuit board insertion/retraction device;  
         [0013]    [0013]FIG. 2 shows the circuit insertion/retraction device of FIG. 1 pivotally attached to a corner of a circuit board just prior to engaging the circuit board housing;  
         [0014]    [0014]FIG. 3 shows the insertion/retraction device of FIG. 1 after engagement a board housing;  
         [0015]    [0015]FIG. 4 shows the insertion/retraction device of FIG. 1 just prior to being latched to the circuit board;  
         [0016]    [0016]FIG. 5 shows the insertion/retraction n device of FIG. 1 latched to the board, holding the circuit board in place within a connector at the back of the housing;  
         [0017]    [0017]FIG. 6 shows the insertion/retraction device of FIG. 1 being disengaged from the circuit board in preparation for removing the circuit board from the connector at the back of the housing;  
         [0018]    [0018]FIGS. 7 through 15 shows various stages of locking the insertion/retraction device to the board;  
         [0019]    [0019]FIGS. 16A and 16B show top and bottom views, respectively, of one embodiment of the latching mechanism of the insertion/retraction device shown in FIG. 1; and  
         [0020]    [0020]FIG. 17 shows a partial cut-away view of a housing having connectors at the back thereof for receiving circuit boards.  
     
    
     DETAILED DESCRIPTION  
       [0021]    [0021]FIG. 1 shows one embodiment of insertion retraction device  10  with leading end  15  for engaging with an edge of a connector housing (e.g., edge  24  of connector guide  23  shown in FIG. 2) and trailing end  16  for releasably latching to the circuit board, as will be detailed more fully hereinafter. Edge  15  has notch  11  which engages the housing and has hole  102  for pivoting around a pin passed through a host circuit board.  
         [0022]    Advantageously, device  10  has an upper portion  17  and a lower portion  18 , separated by gap  104  which comprise the main longitudinal body  12 . Within gap  104  of the illustrated embodiment is spring  106  which pivots around pin  105 , as will be discussed hereinafter, to apply outward pressure on device  10  when the device is engaged with a circuit board. Pin  105  may also serve to maintain gap  104 . Thumb tab  14  allows a user to apply force on device  10  to push a PWB into a connector and to pull the PWB out of the connector, as will be discussed. Latching mechanism  1600  (shown in more detail in FIGS. 16A and 16B) is surrounded by a housing having top cover  210  and side cover  211 . The operation of latching mechanism  1600  will be discussed hereinafter.  
         [0023]    [0023]FIG. 2 shows device  10  connected to PWB  20  by pivotal pin  220  positioned through hole  102 . Guide  23 , such as may comprise a portion of a larger housing (such as housing  1700  of FIG. 17), and PWB  20  are shown cut-away. The portion of PWB  20  that is not shown in FIG. 2 preferably contains a connector portion which mates with connectors in the back portion of a corresponding housing, such as housing  1700  of FIG. 17. Also not shown are board guides which extend from the back portion of guide  23  along the sides of the housing. Guide  23  preferably positions PWB  20  into the connector according to embodiments of the invention. While PWB  20  is shown in a horizontal position, PWB  20  could also be mounted vertically or in any other orientation and the same principles discussed herein would apply. Also note, that while device  10  is shown on the right side of PWB  20 , device  10  could be positioned on either side, or preferably on both sides.  
         [0024]    Outer edge of guide  23  of the illustrated embodiment contains edge  24 , which in this embodiment has a U-shape configuration, but could be any of several configurations. Notch  11  of device  10  has a shape that allows it to engage with the shape of edge  24 . The relative shapes of elements  11  and  24  as well as end  15  (including areas  221  and  222 ), can be adjusted as desired.  
         [0025]    As shown in FIG. 2, PWB  20  has outer edge  21  which has been recessed in this embodiment at area  22  to accept at least a portion of device  10 . This recess is advantageous if it is desired to have the front surfaces of inserted PWBs, having device  10  thereon engaged, relatively flat. Opening  104  (between lower portion  17  and upper portion  18 ) is adapted to clear any parts which might be mounted at the outer edge of PWB  20 . Mounted on PWB  20  of preferred embodiments is a protrusion, such as pin  30 . The purpose being such that when the board is forced into the mating connector and device  10  has been rotated toward PWB  20  (to the left in FIG. 2), and force has been removed from the outer edge of device  10 , the board will remain latched in position by a wedge formed between pin  30  and the engagement of notch  11  with guide edge  24 . This wedge can be thought of as an over-center snap lock.  
         [0026]    As shown in FIG. 3, the user presses on the outside surface of tab  14  of device  10  thereby forcing PWB  20  backward (in the direction of arrow  225 ) within a housing so that the contacts at the back edge of PWB  20  (shown in FIG. 17) become mated with a corresponding connector (shown in FIG. 17). As connector  10  rotates around pivot pin  220 , PWB  20  is forced backward and upper and lower portions  17  and  18  slide over edge  21  of PWB  20  to the point where spring  106  (FIG. 1) contacts area  22  of edge  21 . Note that in the position shown in FIG. 3, the leading edge of slide  19  of latch  1600  has not yet engaged pin  30 .  
         [0027]    As shown in FIG. 4, the leading edge of slide  19  engages (and passes beyond) pin  30  such that pin  30  enters opening  34  in latch  1600 . Spring  25  provides a bias force to latch  1600  (to the left in FIG. 4) such that latch  1600  rotates around pin  103  while device  10  rotates around pin  102 , forcing pin  30  to enter opening  34  and come to rest against stop  32 . At this point in the operation of device  10 , the user is preferably still applying insertion force on device  10  via tab  14 . This operation preferably ensures that the board contact edge over travels into the housing connector further than is actually necessary for electrical contact while this pressure is being applied to tab  14 .  
         [0028]    In FIG. 5 the user has removed the external force from tab  14  allowing device  10  retreat toward the user under control of force applied by spring  106  (shown best in FIG. 1). This outward force on device  10  allows pin  30  to move past the end of stop  32  and into notch  31 . This outward force also allows PWB  20  to move slightly back out of its mating connector, thereby accommodating the over travel discussed above. If desired, this motion could result in positive feed-back, such as a click or tactile sense, so that the user hears and/or feels the positive latching of device  10  onto pin  30  of PWB  20 . At this point, the over-center movement created between pin  30  and notch  11  in mating relationship with edge  24  of guide  23  serve to latch PWB  20  into the connector at the back of the housing. The over-center nature of this force locks device  10  in place, thereby providing positive force serving to maintain PWB  20  positioned inside the connector for positive electrical contact.  
         [0029]    As shown in FIG. 6, when it is desired to release PWB  20  from the connector, the user may apply inward force to device  10  via tab  14 . This inward force combined with the bias force from spring  25  serves to allow pin  30  to exit latch  1600  via opening  33 . Once pin  30  exits opening  33 , device  10  is free to rotate outward around pivot pin  220  and away from PWB  20 , thereby allowing PWB  20  to be removed from the housing.  
         [0030]    [0030]FIGS. 7 through 15 show schematic views of various stages of the locking mechanism just described with respect to pin  30 .  
         [0031]    In FIG. 7 device  10  is being rotated toward a latched position (the lower portion is moving to the left in the figure) such that a leading edge of slide  19  of latch  1600  is just contacting pin  30  on PWB  20 . The leading edge of slide  19  slides along pin  30  as device  10  continues to rotate to the left.  
         [0032]    [0032]FIG. 8 shows pin  30  sliding down the lower surface of the leading edge of slide  19  while spring  25  applies a bias force holding against pin  30  slide  19 . As device  10  rotates more toward the latched position, pin  30  moves toward opening  34  in latch  1600 .  
         [0033]    [0033]FIG. 9 shows pin  30  entering latch  1600  via opening  34  and moving toward stop  32 .  
         [0034]    [0034]FIG. 10 shows pin  30  in contact with stop  32 . According to a preferred embodiment, pin  30  can move no further relative to latch  1600  until insertion force (left rotation of device  10 ) is removed from device  10 .  
         [0035]    [0035]FIG. 11 shows device  10  moving slightly outward under force supplied by spring  106 , thereby allowing pin  30  to enter notch  31 . At this point, device  10  has pivoted around pivot pin  220  in an over-center fashion (between pin  30  and edge  24  (FIG. 2)) such that the board on which device  10  is mounted cannot be removed from the housing until device  10  is released from pin  30 .  
         [0036]    [0036]FIG. 12 shows where slight inward (insertion direction) force has been applied to device  10 , such as via tab  14  (FIG. 3) thereby moving latch  1600  slightly (to the left in FIG. 12), thereby releasing pin  30  from notch  31 . Bias force provided by spring  25  causes latch  1600  to rotate about pin  103  (down in FIG. 12) allowing pin  30  to exit latch  1600  through opening  33 .  
         [0037]    [0037]FIG. 13 shows pin  30  having exited latch  1600  through opening  33 . As shown in FIG. 13, device  10  is now free to rotate toward a release position (to the right in FIG. 13). As shown in FIG. 14, pin  30  moves along the trailing side of edge of slide  19  as device  10  is continued to be rotated toward a release position. FIG. 15 shows device  10  in a release position, i.e., pin  30  is disengaged from latch  1600 , and the board to which device  10  is attached can now be removed from the housing (FIG. 2).  
         [0038]    To aid in the understanding of the foregoing, an embodiment of latch  1600  as described in FIGS. 7-15 is shown separate from the remainder of device  10  in FIGS. 16A and 16B. Specifically, FIG. 16A shows the top view of latch  1600  and FIG. 16B shows the bottom view.  
         [0039]    [0039]FIG. 17 shows a cut-away view of housing  1700  having guide  23  having connectors,  1701  mounted along the back side of the housing with PWB  20  positioned therein. PWB  20  has contacts  1702  for electrically mating with contacts within a mated connector  1701 . PWB  20  is shown with two devices  10 , but could only have one mounted on either side, if desired. Device  10  can be permanently mounted to PWB  20 , or can be slipped over pin  220  (FIG. 2) when desired.  
         [0040]    Although embodiments have been described herein with reference to directional and/or relative terms, such as top, bottom, left, right, it should be appreciated that the concepts of the present invention are not limited to application in any particular orientation. References to such directional and relative terms has been provided for aiding the reader in understanding the concepts of the present invention.