Abstract:
A lever-type latch assembly is mountable onto an outer edge rail of a PC board or module. The lever portion pivots on a base mounted to the edge rail. An ergonomically shaped catch slides within the lever and has a pair of tab bearing snap fingers that ride on shoulders on the inner sidewalls of the lever. A pawl extends outwardly from the pivoted end of the lever having a pair of feet straddling the base mount. Alternately, a bump can be included on the base to provide a detent function. The slide catch carries a pair of locking tabs. The base includes a pair of mating locking tabs. The catch is spring biased towards the base pivot position, thereby biasing the catch looking tabs into overlapping contact with the base locking tabs. The catch can have a flat outer face for a product label.

Description:
RELATED APPLICATIONS 
   Background of the Invention 
   The present invention relates to latches and levers, specifically ejector latches and ejector levers which may be adapted for use to secure and release objects in tight quarters, such as printed circuit boards (PC boards) and the like held in cabinets or on electrics card racks. 
   Electronic modules held in larger enclosures may take the form of PC boards or PC cards mounted to slide in a rack, a tray, or along a rail, or which can be pressed into a connector slot. It has become increasingly important to be able to easily insert such a module with a positive “click-type” (or snap-in type) connection, and with a positive release. Moreover, it has become increasingly important to have an insertion aid and/or a pull-out aid such as a handle or a hold. 
   A combination inject-eject latch would be suitable for such uses. These devices have been introduced into the art for other applications, also. Such latches can be mounted on the face of a panel or drawer, so that it (they) is (are) capable of injecting a board or module, mounted thereto, into and out of a draw or rack. The latch acts to retain the electronic module within an enclosure in order to maintain the electrical connection thereof even when jarred or jostled. 
   These latches generally include an elongate handle, of lever-like shape, which can provide a grasping surface to assist in the inserting and removal of the attached board or module from the rack in which it mounts. The handle has pivoted into the rack during the injection operation and pivoted out of the rack during the ejection operation. Attached to the handle is a pawl which when the handle moves engages against surfaces of the associated fixed housing/rack keeper, to “pry” there against thereby providing the injection and ejection force. This movement positions a board to which the lever is attached into a seated position or an unseated position in the housing or rack. 
   Generally, these latches have utilized a biasing spring or biased spring clip that functions to keep the handle in the downward fully pivoted position. A release is needed to move against the spring force. This has been accomplished with a grasping tab positioned on the biased spring clip, or a release button which compresses the biasing spring which in releases the kept position of the handle and permits upward/outward pivoting movement thereof. This in turn facilitates ejection of the associated board or module, as the pawl connected to the handle pries against a surface of the keeper and thereby moves the board or module to which the lever is mounted into an unseated position. Once this is accomplished, grasping the handle facilitates the removal of the board or module. 
   PC cards (and PC boards) generally have narrower rack footprint than PC modules, as PC modules are generally larger and heavier boards, which often carry a reasonably wide rail at the outward edge, and a connector at the opposite edge. Often guide pins, attached to a structure mounted at each side edge of a card or board, are employed. These guide pins assist in the proper alignment of the PC card or board or module with seating into the connector. 
   Manufacturers like Rittal International (Germany), Hoffman-Schroff electronic packaging division (Singapore) of Pentair, Inc. (USA), and Elma Electronic, Inc. (USA) electronic packaging subsidiary of Elma Electronic AG (Switzerland) have provided PCI (peripheral component interconnect) equipment for the computer and electronics industry. These manufacturers each supply module inject-eject CPCI (computer peripheral connection interconnect) cabinet, rack, or housing latches. Representative of these is the Rittal International part no. 3686135 product. These ejectors each require an outer edge rail or its equivalent to provide a needed mounting surface for the latch. This rail, which is mounted to the PC board, acts as a faceplate, mounting surface, much as with the panel or drawer need to mount the latch described above. The Rittal International latch engages a portion of a housing rack structure to inject and eject the connection of the PC module connector. 
   These PCI latches also each require a separate positive lockout structure to provide a lockdown function. Often used is a separate plate such as a hold down lever or hold down plate. The Rittal International latch has a keeper mounted outwardly from the face of the rail. A positive lockout slide is carried on the assembly as part of a pivoting lever and engages the keeper when the lever is pivoted to the closed position (injected position) to secure the latch in the closed/locked position. Generic to PCI latches is a finger or thumb grasping space, which requires the lever assembly to have a higher profile. 
   PC card levers and pullers are provided by a number of manufacturers including Calmark Corp. (USA), Richco, Inc. (USA) and Southco, Inc. (USA). Calmark provides a part no. 107-20 PC card inserter-extractor latch. This is a one-piece lever, which is pinned to a PC card near its outside edge to enable it to pivot. The lever includes a snap-type detent foot, which engages a second pin extending through the card when the lever is in the downward/closed position. This engagement acts as a pressure or friction hold down. The lever has an upraised finger grasping end. The opposite end of the lever carries a pawl which engages a C-shaped housing or rack mounted flange which acts as the latch keeper. The lever is manually pivoted to the outward position to disengage pawl from the keeper. In doing so, the detent force is overcome. 
   Richco provides a part no. R1107 PC card inserter-extractor latch. This latch is similar in shape and function to the Calmark latch, and similarly mounted to pivot. An exception is that the Richco lever is without the detent foot or a second pin. 
   Southco provides a part no. 90-0-6503-11 PC card inject-eject latch. The Southco latch pivots on a rivet through the PC card positioned near its outside edge. The Southco latch has a very long handle, which is grasped by drawing a finger and thumb along the PC card to catch the handle. The handle is without a detent or other closed/locked position-holding structure. It is intended to seat down on the outside edge of a card when in the closed position. This Southco handle carried a pair of rounded foot extensions at its opposite ends which act as pawls to engage a curved spring flange which is rack or housing mounted. This engagement affects the injection and ejection functions of the latch. 
   In attempt to make smaller footprints for electronic component housings and racks, and to include more component modules in a smaller space as circuits become smaller, there is an ever increasing desire to pack PC cards, PC modules and the like closer together and with less housing clearance. 
   Moreover, clearances between the outward edge of each PC card, board or module and the outward end of the housing or rack are also being reduced. Where a card, board or module uses an outward edge rail for support the necessity for a low profile lever or latch is increased. 
   The goals and issues of designing evermore simple, less costly and stronger levers and latches are constantly in the forefront. Plastic parts are generally less costly to manufacture than metal parts. However, depending upon the design, plastic parts are generally weaker, have lower heat tolerance, and are less durable than metal parts. 
   Ease of assembly of a lever or latch assembly is also a goal. Ease of operation and the absence of binding and wear failures are also concerns. 
   It therefore has become desirable to provide a card or module injection-ejection latch with an elongate, lever-like handle and a low profile when in the closed position. 
   It is further desirable to provide this inject-eject latch with a base structure that is mountable to the outer edge rail for a PC card, board or module. 
   It is also desirable to provide this inject-eject latch with a positive lockout at its closed or rotated down position, and a positive detent-like function at its open position without adding additional parts. 
   It is additionally desirable to provide this inject-eject latch with a structure for its catch, pawl, lockout and detent functions that are each implemented in with plastic parts. 
   It is even further desirable to provide this inject-eject latch with a snap in assembly. 
   It is further additionally desirable to distribute the stresses on the plastic catch by incorporating a multiple catch structure without increasing the space requirements for the latch. 
   It is lastly desirable to create an ergonomic design for the catch member of the latch. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide an improved PC board rotatable lever ejector latch design which incorporates double catch members for effecting a positive lockout at the latch closed position, i.e., the rotated down position, wherein the locking mechanism can be made of plastic or other lighter material and be strong enough to withstand the forces normally handled by metal parts. 
   A second object of the present invention is to provide an ergonomic shaped catch member. 
   A third object is to provide a detent function at the fully open position, i.e., the fully rotated up position. 
   A further object is to incorporate a label bearing surface on the catch, thereby eliminating a label bearing surface on the lever. 
   The objects of the present invention and other features are incorporated into a rotatable lever-type inject-eject latch for a PC board, PC card, electronic module, or other device that is inserted and removed from a housing or a rack. This lever assembly has three major components of which two can be made of plastic or other moldable material. A biasing spring completes the component list for a total of four assembled parts. 
   This lever assembly includes a base member, which is mounted to the PC board et al. directly or via an edge rail. The base has an upward-outstanding wall on which is located a pivot bearing point including a pivot. The outer edge of the base standing wall is rounded. 
   The base also includes a pair of locking tab projections, which can be horizontal projecting, i.e., parallel to the outer edge of the PC board or edge rail if present. These tabs can be finger or wedge shaped and are positioned sequentially, one behind the other along a longitudinal line extending along the base. 
   An elongate lever member is pivotally mounted at near one end thereof to the pivot at the bearing point on the base standing wall. A pawl is molded into the disparate end of the lever to extend from the pivot point longitudinally outwardly. This pawl is claw shaped and has a top solid lip implemented with a transverse bar member, and a bifurcated lower lip implemented with two parallel extending feet. 
   The body of the lever is hollow with an elongate rectangular opening in the top surface thereof. A recessed slide way is implemented in the top surface of the lever with the presence of undercut shoulders about the opening. Longitudinally extending shoulders run along each inner sidewall of the lever. 
   The end of the lever opposite the pawl is feather tapered for ergonomic grasping. At this grasping end of the lever are included a pair of downwardly extending guide pins, which can project through mating openings in a edge rail to facilitate assembly alignment of the latch thereto. 
   The entire lever structure, including the pawl portion can be manufactured as a single injection molded plastic part. 
   A catch is mounted to slide on the lever. This catch has an ergonomic shaped operating tab at one end which extends upward-outwardly. The catch also has a flat plate configuration which fits into the lever recessed slide way and rides on the undercut shoulders thereof. The flat plate outer face of the catch is suitable for carrying a product label. 
   A pair of locking projecting tabs are positioned in sequential fashion, one behind the other, along a longitudinal axis of the catch. These catch locking tabs are approximate each longitudinal end of the catch and on the underside of the catch so as to operate within the lever opening. These catch locking tab projections face the pivot point of the lever and therefore face the respective base locking tab projections in the assembled structure. Like the base locking tabs, the catch locking tabs are sequentially spaced one behind the other at a distance consistent with the distance between the base locking tabs. The catch locking tabs extend parallel to the extension of the catch which in turn extends parallel to the extension of the lever, with the catch locking tabs extending parallel to the edge of the PC board and parallel to the extension of the base locking tabs when the lever is in the closed position. When the catch locking tabs engage the base locking tabs, the catch and lever are locked into fixed position with respect with the base. This engagement can be an overlapping of the respective locking tabs. 
   To facilitate locking engagement each of the base locking tabs and the catch locking tabs include a ramped camming surface at the end thereof. When the catch locking tabs are rotated into the base locking tabs the respective ramped camming surfaces engage and the catch is forced away from the lever pivot location, i.e., the pawl portion of the lever. 
   At the operating tab end of the catch is a spring housing which has a circular hole for containing a coiled biasing spring, which also seats against the adjacent end of the lever when assembled. This biasing spring biases the catch towards the pawl portion of the lever, this biased position being the catch locking position. Whether the lever is in the locked position or not will depend upon whether the catch and the lever are rotated to the closed position or rotated into to another angular position. 
   The catch also has a longitudinally and upward-outwardly extending arm at the end opposite the operating tab. A portion of this arm engages the rounded outer edge of the base standing wall when the spring biases the catch towards the pawl end of the lever. This position is the locking position for the catch. The extending arm has a projecting tab or finger that provides an angled inner surface for engaging the base standing wall. The angled inner surface can include an inward corner. When a bump, or outward circular protrusion is present on the rounded outer edge of the base standing wall, a detent is created with the inward corner of the catch extending arm. This detent will hold the lever in position at its extreme rotational position at the ejection end position. 
   A guide structure extends below the ergonomic tab location on the catch and in the direction away from the lever pawl. This guide structure acts to keep the catch from unintentionally exiting the lever opening when the catch is at its far locking position. 
   As an alternative to the detent bump on the rounded outer edge of the base standing wall, the lever can be held at its extreme rotational position being the ejection end position by an axial interference of the pawl feet with the base standing wall. This can be accomplished by have the free end of the pawl feet come into a friction contact with the base standing wall. A tapering inwardly of the free ends of each pawl foot will create this axial interference. Alternatively to this taper, a juxtaposed inward facing tabs or shoulders can be placed at the extreme free ends of the pawl feet. When the pawl is in its extreme eject position these tabs or shoulders come into friction contact with the base standing wall providing a holding function. 
   The catch also includes a pair of parallel extending snap fingers, which extend into the lever opening. Each snap finger has a tab projecting transversely at its end. These snap finger tabs engage the lever inner sidewall shoulders to keep the catch within the lever opening and permit the slide operation. The catch can be manufactured as a single injection molded plastic part. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features, advantage and operation of the present invention will become readily apparent and further understood from a reading of the following detailed description with the accompanying drawings, in which like numerals refer to like elements, and in which: 
       FIG. 1  is a perspective partial view of the ejector latch with double catch of the present invention in the closed position; 
       FIG. 2  is a top plan view of the closed ejector latch of  FIG. 1 ; 
       FIG. 3  is a pawl side end view of the closed ejector latch of  FIG. 1 ; 
       FIG. 4  is a ergonomic tab side end view of the closed ejector latch of  FIG. 1 ; 
       FIG. 5  is a side elevation view of the closed ejector latch of  FIG. 1 , with the opposite side elevation being the mirror image thereof; 
       FIG. 6  is a bottom plan view of the closed ejector latch of  FIG. 1 ; 
       FIG. 7  is a plan view of the ejector latch of  FIG. 1  in the closed and locked out position; 
       FIG. 7   a  is a cross-section view of the ejector latch taken as shown in  FIG. 7 ; 
       FIG. 8  is a plan view of the ejector latch of  FIG. 1  in the closed but unlocked (unlatched) position; 
       FIG. 8   a  is a cross-section view of the ejector latch taken as shown in  FIG. 8 ; 
       FIG. 9  is a plan view of the ejector latch of  FIG. 1  in the fully open position; 
       FIG. 9   a  is a cross-section view of the ejector latch taken as shown in  FIG. 9 ; 
       FIG. 9   b  is an enlarged top elevation view of the fully open latch, this figure being an enlargement of  FIG. 9 ; 
       FIG. 9   c  is p cross-section of the fully open ejector latch having a detent bump and taken as shown in  FIG. 9   c;    
       FIG. 10  is a side elevation of the ejector latch of  FIGS. 1 and 7   a  in the closed and locked out position while engaging a chassis keeper; 
       FIG. 11  is a side elevation view of the ejector latch of  FIGS. 1 and 9   a  in the fully open position while engaging a chassis keeper; 
       FIG. 12  is a perspective view of the base member of the ejector latch of  FIG. 1 ; 
       FIG. 13  is a top plan view of the base member of  FIG. 12 ; 
       FIG. 14  is a pawl side end view of the base member of  FIG. 12 ; 
       FIG. 15  is an ergonomic tab side end view of the base member of  FIG. 12 ; 
       FIG. 16  is a side elevation view of the base member of  FIG. 12 , the opposite side elevation being a mirror image thereof; 
       FIG. 17  is a bottom plan view of the base member of  FIG. 12 ; 
       FIG. 18  is a perspective view of the lever member of the ejector latch of  FIG. 1 ; 
       FIG. 19  is a top plan view of the lever member of  FIG. 18 ; 
       FIG. 20  is a pawl side end view of the lever member of  FIG. 18 ; 
       FIG. 21  is an ergonomic tab side end view of the lever member of  FIG. 18 ; 
       FIG. 22  is a side elevation view of the lever member of  FIG. 18 , the opposite side elevation being a mirror image thereof; 
       FIG. 23  is a bottom plan view of the lever member of  FIG. 18 ; 
       FIG. 24  is a perspective view of the catch member of the ejector latch of  FIG. 1 ; 
       FIG. 25  is a top plan view of the catch member of  FIG. 24 ; 
       FIG. 26  is a pawl side end view of the catch member of  FIG. 24 ; 
       FIG. 27  is an ergonomic tab side end view of the catch member of  FIG. 24 ; and 
       FIG. 28  is a side elevation view of the catch member of  FIG. 24 , the opposite side elevation being a mirror image thereof; 
       FIG. 29  is a bottom plan view of the base member of  FIG. 24 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention is an improved PC board mounted rotatable, inject-eject lever latch assembly, which incorporates double catch action for spreading the stresses on the catch member thereof. The latch provides both catch (lock-out) functional structure and detent (hold open) functional structure. The latch assembly is implemented in three major component parts, a base member, a lever member and a catch member; and a separate biasing spring. Two of the component parts, the lever and the catch, can be made of injection molded plastic material. 
   The present invention has the catch member carried on the lever member and moveable in relationship thereto and to the base member. The invention also places a catch lockout on the catch member as far from the lever rotation pivot point position as the structure will permit, and places a detent as close to the pivot point position as the structure will permit. Plastic material being for both the lever and catch member permits ergonomic features to be incorporated in each. A pair of smaller locking projections, on the catch member, act as the catch points for locking the catch and lever to the base member. The two smaller catch points replace a larger one needed for operation. Thus the latch assembly has a lower closed profile and the two latch points distribute the stresses and applied load over a greater section of the catch member, permitting the use of lower strength materials, such as plastics. The detent in one embodiment thereof may be implemented with structure which applies an axial interference between the lever member and the base member. 
   The inject-eject, rotatable, lever-type latch  50 ,  FIG. 1 , has its lever member  101  mounted to its base member  103  with a pivot pin  105  connection,  FIG. 1 . A catch member  107  is carried on the lever  101 . The lever  101  is substantially elongate and rectangular,  FIGS. 2–6 . At one end of the lever  101  approximate the pivot bearing point of the pivot pin  105 , is a claw shape pawl  109 . This pawl  109  has an upper lip which is implemented by a transverse bar  111  and a lower lip implemented by a pair of parallel projecting feet  113 . The opposite end of the lever  101  is a feather tapered tail, grasping surface  115 . 
   The catch member  107  seats into and rides on the top plane of the lever  101  for slide movement in respect thereto. At the end of the catch  107  approximate the feather tapered tail  115  of the lever  101  is an upstanding curved, ergonomic shaped finger tab  117 . The tab is moved by the operator to move the catch  107  with respect to the lever  101  and the base  103 , which remain fixed together by the pivot pin  105 . 
   A cross-section of the latch assembly is shown in  FIGS. 7   a ,  8   a  and  9   a , each of which views is taken as shown respectively in  FIGS. 7 ,  8  and  9 . The base  103  includes an upward-outwardly standing wall  119  that carries the pivot point for the pivot pin  105 ,  FIGS. 7   a ,  8   a ,  9   a . The base  103  has a pair of sequentially spaced locking projection tabs  121 ,  123 , one positioned behind the other. Respective mating catch locking projection tabs  125 ,  127 , are likewise positioned sequentially, one behind the other. The catch locking tabs  125 ,  127  face the base locking tabs  121 ,  125 . When the tab  121  engages and overlaps the tab  125  and the tab  123  engages and overlaps the tab  127 , the latch  50  is in the closed and locked position,  FIG. 7   a . In the closed and locked position,  FIG. 7   a , the catch  107  is fixed to the base  103  thereby fixing the lever  101  carrying the pawl  109  as well. 
   The base  103  standing wall  119 ,  FIGS. 7   a ,  8   a ,  9   a , has a round outer face  129  upon which rides an outwardly extending arm  131  from the catch  107 . This occurs when the catch  107  is biased forward toward the pivot  105 ,  FIGS. 7   a  and  9   a . When the catch  107  is operated to the unlatched position,  FIG. 8   a , the catch  107  extending arm  131  is retracted away from the base  103  standing wall  119 ,  FIG. 8   a.    
     FIG. 9   b  is an enlarged view of  FIG. 9 , both of which show the latch  50  in the fully rotated open position.  FIG. 9   c  is an enlarged partial cross-section of the fully opened latch  50 , taken as shown in  FIG. 9   b . In this view,  FIG. 9   c , the base  103 , standing wall  119 , round outer face  129  has a round detent bump  133  on it. This detent bump  133  seats into a notch  135  in the extending arm  131  formed by an inward corner on the inner surfaces thereof. Each of the base  103  locking tabs  121 ,  123  is shown with its respective ramped ends  137 ,  139 . The catch locking tabs  125  (not shown) and  127 , each have respective ramped ends  141  (not shown) and  143 . 
   The base  103 , of course is fixed, with the lever  101  and its carried catch  107  being movable, rotationally upward and downward, in  FIG. 9   c . The taper of each engaging ramp end, i.e.,  137  onto  141  and  139  onto  143  is angled such that when the lever  101  is rotated down, carrying the catch  107  with it, the movable ramp surface  141  engages the fixed ramp surface  137 , with the same being for the movable ramp surface  143  engaging the fixed ramp surface  139 , so that the catch  107  is moved back away from the pivot  105  by the camming operation of the interacting ramped surfaces. 
     FIGS. 10 and 11  shown the latch  50  engaging a chassis keeper  145 , with  FIG. 10  illustrating the closed position and  FIG. 11  illustrating the open position. In fact, in  FIG. 11  the latch  50  is partially moved upward by the force of the ESD spring  147  which rides on the guide insertion pin  149 . The base  103  can be attached to a PC board edge rail with the downward extending attachment or anchoring member  151 . 
   The configuration of the base member  103  can be seen in detail in  FIGS. 12–17 . Base member  103  has a flat plate portion  153  upon which the locking tab projections  121 ,  123  sit. Each locking tab projection  121 ,  123 , has a base  155 ,  157 , respectively, and a flat blade-like tab projection  159 . The second tab projection  123  is formed integral with the standing wall  119 . The guide insertion pin  149  and the base attachment member are positioned on the opposite side of the flat plate  153  from the locking tabs projections  121 ,  123  and the standing wall  119  opposite side. The base member  103  can be a single piece machined metal part. The base  103  can also be made as a fiberglass reinforced resin part or an injection molded plastic part. 
   The configuration of the lever member  101  is shown in detail in  FIGS. 18–23 . The lever  101  is essentially of flat shape with an opening  161  through its body. The claw shaped pawl  109  is molded into one end, while the feather tapered tail  115  is molded into the opposite end. A recessed slide way  165  faces the top face of the lever  101 . This slide way is defined by the undercut shoulders  163  in the upper face of sidewalls of the opening  161 . The catch  107  slides on these undercut shoulders  165 . Beneath the undercut shoulders  165  in the inner sidewalls of the opening  161  are juxtaposed shoulders  167  extend longitudinally along the sidewalls of the opening  161 . 
   Approximate the feather tapered tail area  115  is a pair of assembly guide pins  169  which extend downwardly. The lever member  101  is intended to be made as a one piece injection molded part. As with the base  103  discussed above, and the catch  107  discussed below, the lever  101  may have certain surfaces polished, machined, or otherwise machined after molding or forming. However, this machining is not required unless specified tolerances, clearances, and fits-of-shape are specified in manufacturing. 
   The pawl feet  133  can each carry a protrusion tab  171  at their extreme outer ends or can have their juxtaposed surfaces tapered towards one another or both. 
   The configuration of the catch  107  is shown in detail in  FIGS. 24–29 . The catch  107  has a flat plate-like portion  173  on which a product label may be attached. The upstanding operator tab  117  is curved to a ergonomic shape. The extending arm  131  has at least one notch  135  for engaging the detent bump  133  on the base standing wall  119 . Extending downwardly from the plate structure portion of the catch  107  are a pair of snap fingers  175 ,  177 , each within a juxtaposed facing end tab  179 . The snap fingers  175 ,  177  extend into the lever opening  161  and the snap finger tabs  179  engage the longitudinal shoulders  167 , for snap-in assembly of the catch  107  into the lever  101 . A lip structure  181  extends outwardly from beneath the operator tab  117  end of the catch. This lip also carries the biasing coil spring  183  which operates to bias the catch  107  away from the feather tapered end  115  of the lever  101 . 
   Many changes can be made in the above-described invention without departing from the intent and scope thereof. It is therefore intended that the above description be read in the illustrative sense and not in the limiting sense. Substitutions and changes can be made while still being with the scope of the appended claims.