Device and method for circuit board insertion and removal

This invention relates to circuit board latches and more particularly to a device and method for circuit board insertion and removal.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

FIG. 1 shows an isometric view of one embodiment of a circuit board insertion/retraction device;

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;

FIG. 3 shows the insertion/retraction device of FIG. 1 after engagement a board housing;

FIG. 4 shows the insertion/retraction device of FIG. 1 just prior to being latched to the circuit board;

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;

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;

FIGS. 7 through 15 shows various stages of locking the insertion/retraction device to the board;

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

FIG. 17 shows a partial cut-away view of a housing having connectors at the back thereof for receiving circuit boards.

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.

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.

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.

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.

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.

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 .

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 .

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.

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.

FIGS. 7 through 15 show schematic views of various stages of the locking mechanism just described with respect to pin 30 .

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.

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 .

FIG. 9 shows pin 30 entering latch 1600 via opening 34 and moving toward stop 32 .

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 .

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 .

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 .

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 ).

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.

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.

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.