Abstract:
A circuit board insertion and extraction apparatus. The present invention is a circuit board inserter and extractor apparatus particularly suited for use with circuit boards utilizing high insertion force connectors requiring in excess of 50 lbs of force. The handle of the inserter/extractor has novel insertion and extraction surfaces which cooperate with corresponding surfaces fabricated as part of a card guide. As the circuit board is inserted into the card guide, the handle is automatically positioned so that the user can press the bottom of the handle to insert the circuit board. The handle and card guide interface is designed to provide a large positive force to extract the circuit board from the card guide until the circuit board is unseated from the associated high insertion force connectors. Additionally, the present invention is advantageously designed to eliminate the need for fixtures or separate hardware to install the handle onto the circuit board thereby saving assembly line time and money.

Description:
FIELD OF THE INVENTION 
     This invention relates to circuit board/backplane interfaces and particularly to a device to aid in the insertion and extraction of a circuit board from a system utilizing high insertion force connectors. 
     BACKGROUND OF THE INVENTION 
     In recent years, printed circuit boards have been used extensively in electrical equipment. For example, computers are routinely constructed of a plurality of printed circuit boards each containing a portion of the electronics required to allow the computer to operate. In computer designs it is common to require several circuit boards to be inserted in a closely-spaced parallel relationship into a card cage having a card guide for every circuit board. A contact arrangement consisting of a card edge or connector on the leading edge of each of the circuit boards engage an electrical connector when the circuit board is fully inserted into the card cage. 
     The amount of force required to seat a circuit board into a backplane is dependant on the number of contacts and type of electrical connectors used. Typically, the more contacts that must be mated, the more force that must be used to seat the circuit board. Today, computer circuit boards utilize a high number of electrical connections which require high insertion force. Therefore a large amount of force is required to properly seat circuit boards into their backplane connectors. The task of seating the boards is made even more difficult because of the close spacing of circuit boards in the card cage. 
     With respect to extraction of a circuit board from the backplane, tight board-to-board spacing presents an obstacle to firmly grasping the trailing edge of the circuit board. Also it takes a large amount of force to extract a circuit board utilizing high insertion force connectors. This force is hard to apply in the typically small space available for grasping with a human hand. 
     It is common to provide a cam lever, pivotally attached to a trailing edge corner of a circuit board to facilitate circuit board removal. The camming action of such a device against the card cage provides a limited amount of extraction, and the device often not aid in circuit board insertion. Also, these devices require tools and fixtures to attach them onto the circuit boards which increases the time and expense to assemble a complete circuit board assembly. 
     The prior art devices also require separate engaging devices to be mounted onto the card guides. These engagement devices complicate and increase the time and expense required for the card cage to be assembled. 
     What is needed in the industry is a circuit card inserter and extractor device which can be assembled onto a circuit board quickly and without tools, can supply high insertion and extraction forces, does not require a separate engagement device, and can be used with a circuit board that is shorter then the card cage is deep. 
     SUMMARY OF THE INVENTION 
     The present invention is a circuit board inserter and extractor apparatus that provides the high forces required by today&#39;s circuit boards and backplanes utilizing high insertion force connectors. This apparatus consists of three separate pieces. Two of the pieces, an insertion/extraction handle and a retaining clip mount on a circuit board. The third piece consists of engagement surfaces fabricated as part of a card cage, referred to as the handle interface feature. 
     The retaining clip is constructed to fit inside, and be retained by, the handle to form a handle/clip assembly. This assembly is then slid over the edge of a circuit board having both a clip interface and a pivot relief. Features on the retaining clip engage inside these reliefs and securely retain the handle/clip assembly on the circuit board. Once installed on the circuit board, the retaining clip serves to transfer forces from the handle to the circuit board when the circuit board is being inserted or extracted from the card cage. By utilizing this novel attachment method, no tools or fixtures are required to assemble the handle/clip assembly to the circuit board as required by prior art devices. 
     The handle is bent to form a generally long &#34;U&#34; shape channel which is symmetric along the center of the channel. The upper end of the handle has three engagement surfaces, a lead face, a toe and a heel, per side. These engagement surfaces on the handle cooperate with the engagement surfaces of the card cage. As the circuit card is slid into the card cage, the lead faces of the handle strike a set of first faces on the handle interface feature (HIF). This action forces the handle to rotate thereby bringing the toes of the handle into contact with a set of second surfaces of the HIF. By pushing on the bottom of the handle, the toes of the handle are forced into the second surfaces on the HIF. This force is transferred to the circuit board which forces the circuit board into the backplane connector. 
     To extract the circuit board, the bottom of the handle is pulled away from the circuit board causing the handle to rotate and bringing the heel surfaces into contact with a set of third surfaces of the HIF. As the handle is continued to be pulled away, the heel is forced against the third surfaces of the card guide. The resultant force is transferred to the circuit board through the retaining clip which forces the circuit board out of the card cage and backplane connector. As the handle continues to rotate, the lead faces of the handle are forced into contact with the set of first surfaces of the HIF. This force is also transferred to the circuit board forcing the circuit board to continue to move out of the card cage. By the end of the handle rotation, the circuit board and backplane connectors are disconnected. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A and 1B are side and isometric views of the invention mounted on a circuit board and positioned to engage a handle interface feature (HIF). 
     FIG. 2 is a detailed illustration of the engagement features of the insertion/extraction handle and the HIF. 
     FIGS. 3A-3C illustrate the initial engagement between the insertion/extraction handle and the HIF. 
     FIGS. 4A-4C illustrate the insertion/extraction handle positioned to leverage the circuit board into the backplane connectors. 
     FIG. 5A-5C illustrate the insertion/extraction handle in the closed position and the circuit board fully seated into the card cage. 
     FIG. 6A-6C illustrate the insertion/extraction handle initially engaging surfaces on the HIF to eject the circuit board. 
     FIG. 7A-7C illustrate the insertion/extraction handle in the final engagement position relative to the HIF in the circuit board ejection sequence. 
     FIGS. 8A-8F are detailed views of the the insertion/extraction handle. 
     FIGS. 9A-9D are detailed views of the retention clip and the features on the retention clip. 
     FIGS. 10A-10D illustrate the insertion/extraction handle mated with the retaining clip. 
     FIGS. 11A-11D illustrate the handle/clip assembly of FIGS. 10A-10D being attached to a circuit board. 
     FIGS. 12A-12B are detailed views of a section of a HIF incorporated into a card guide. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Operation of the Invention 
     The present invention is constructed in three pieces. An extractor handle manufactured of 1/4 hard stainless steel, a retaining clip made of full-hard stainless steel and a handle interface feature (HIF) incorporated in the card cage. The handle provides an approximately 4.5 to 1 mechanical advantage for inserting and extracting boards utilizing high insertion force connectors. As the handle is made of metal, it does not flex and provides enough leverage to insert or extract circuit boards requiring 60 lbs of force or more. 
     The retaining clip serves three main purposes. First it attaches the handle to the circuit board. Second, it transfers the forces from the handle to the board when the board is being extracted. The clips third function is to fix the handle in the open or closed position and to provide tactile feedback to the user. This tactile feedback is accomplished via 2 bumps on the clip that fall into corresponding dimples on the handle when the handle is fully opened or fully closed. This feature also flees the user from having to hold the handle while the board is being inserted into the card guide and resists the tendency of the card to back out of the card guide once positioned. 
     Except when the handle is fully opened or closed, the bumps on the clip are deflected and provide friction between the handle and clip resulting in a nice feel and stability of the handle. When the bumps fall into the dimples on the handle, the user feels the engagement and thereby knows the handle is either in the closed or open position. 
     The main function of providing the required insertion or extraction leverage is accomplished by the interface between the profile of the handle and the interface features on the card cage. While upper and lower handle interface features and upper and lower extractors are normally utilized, the following description will refer only to the upper HIF and extractor operation for simplicity as the operation of the lower assemblies is identical to what is described. 
     In the following description of the invention, numbers will be used to refer to specific features or areas. The first numeral in a three digit number and the first two numerals in a four digit number refer to the first drawing that reference number is used in. 
     Referring now to FIGS. 1A and 1B, a handle 101 is attached to a circuit board 103 by a retaining clip 105. The handle 101 is free to rotate on a handle pivot 107 (only right side pivot shown). A card guide 113 provides lateral guidance for the circuit board 103 and the first one is integrated into the HIF 109 which includes engagement features 111. The lateral guidance is provided by the restriction feature 113 as is well know in the art. Also included in the HIF are handle engagement centering features 115. 
     FIG. 2 illustrates the engagement features 111 of the HIF and the engagement end of the handle 201. The engagement features 111 of the HIF include three face surfaces, a lead interface bearing surface 203, a heel interface bearing surface 205 and a toe interface bearing surface 207 on each side (right side shown only). The handle also includes three engagement surfaces on each side. These handle surfaces are a lead face 209, a toe face 211 and a heel face 213. 
     To insert a circuit board into the card cage, the handle is placed in the fully open position where it is held by the bum/dimple action (not illustrated) in the handle and clip. The board is placed in the card guide 113 and pushed into the chassis in typical fashion. As the lead face 209 of the handle 101 makes contact 301 with the lead interface bearing surface 203 of the HIF 109, the handle is forced to start to pivot and close. This interaction is best illustrated by FIGS. 3A, 3B and 3C where FIG. 3A is a side view, FIG. 3C is a perspective view and FIG. 3C is a detailed view of the interacting engagement faces of the handle and card guide. 
     Now referring to FIGS. 4A-4C, the board continues into the card cage until connector resistance requires the use of the handle. As the board moves into the card cage, the handle continues to pivot toward the closed position and is properly positioned to insert the board at any point along this path. As the handle continues to close, the point of contact between the handle and the HIF moves from edges 203 and 209 to the toe 211 of the handle and the toe interface bearing surface 207 of the HIF. The handle centering features 115 on the HIF serves to keep the engagement features of the handle and the card guide aligned as required. 
     As best illustrated in FIGS. 5A-5C, when the resistance of the connectors requires the use of the handle, the user pushes on the end 501 of the handle 101 which in turn forces the toe 211 of the handle against the toe interface bearing surface 207 of the card guide. The resultant force is transferred to the board by the handle forcing the pivot 107 against the board 103 thereby causing the board to seat inside the connectors completing the insertion process. The handles are held in the closed position by the bump/dimple action (not shown). 
     A significant feature of this invention is that a card shorter than the card cage can be utilized as the handle to HIF engagement takes place outside of the card guide area. That is, the handle insertion and extraction features straddle the card guide area 113 and can remain open until they meet the corresponding surfaces of the HIF. Therefore, the HIF can be recessed in the card cage, with card guides such as 113 preceding it, allowing a short card to be used in a computer chassis utilizing both long and short cards. This allows the use of a standard card in systems having different card cage depths. 
     As illustrated in FIGS. 6A-6C, to extract a board from a card guide the handle is pulled open by the user thereby forcing the board out of the card cage. By pulling on the extraction thumb tab 601, the handle 101 is forced away from the board 103. As the handle is opened, the heel 213 of the handle is forced against the heel interface bearing surface 205 of the HIF. The resultant force is transferred from the handle 101 through the clip 105 and to the board. This action forces the board to move out of the card cage. 
     Referring now to FIGS. 7A-7C, as the handle 101 continues to open, the point of interface between the handle and card guide moves to the lead face 209 of the handle and the lead interface bearing surface 203 of the HIF. The resultant force continues to be transferred to the board as before forcing the board out of the card cage. In practice, once the board is clear of the electrical connectors, minimal force is required and the board is pulled clear of the card guide by pulling on the board by hand. 
     Construction of the Invention 
     FIGS. 8A and 8B are front and rear isometric views of the handle 101. As illustrated, the handle is constructed of one piece of stainless steel bent to form two sides 801 and 803. Each side includes a thumb tab 601, a handle pivot 107, a lead face 209, a toe 211 and a heel 213. A preferred construction method for this handle is to punch and form the stainless steel in a progressive die out of 0.048&#34; sheet stock. The handle is manufactured with the channel not fully bent into the final position to allow the retaining clip to be inserted into the handle channel. Once the clip is inserted into the handle, the channel is then closed to the final position thereby capturing the clip. 
     FIG. 8C is a rear view of the handle 101. The handle pivots 107 are shown in profile. The handle pivots 107 are designed as a short cylindrical columns that are highly stiff. Each side 801 and 803 are bent outwardly 805 and 807 at the top of the handle. These bends are such that the HIF are sufficiently far apart such that they clear the card guide 113. In this manner, the handle will pass outside of the card guide until it engages the appropriate engagement surfaces on the HIF. 
     FIG. 8D is a sectional view taken along the lines 8D of FIG. 8C. A handle open dimple 811 and a handle closed dimple 809 are illustrated. These dimples cooperate with bumps on the retaining clip to hold the handle in the open or closed position. Each side 801 and 803 has pair of handle open and handle closed dimples. 
     FIG. 8E is a side view and FIG. 8F is a sectional view of the handle 101 taken along lines 8F of FIG. 8E. A best illustrated in FIG. 8F, the handle pivots 107 are formed from material extruded inward by the fabrication tool. Also the two handle closed dimples 809, one in side 801 and one in side 803, are illustrated. While the handle can be of any convenient length, it is advantageously at least 2.5&#34; long to provide sufficient leverage to insert and extract a circuit board utilizing high insertion force connectors. 
     FIGS. 9A and 9B are from and rear isometric views of the retaining clip 105. The retaining clip is formed from 0.012&#34; stainless steel fiat stock and fabricated on a 4-slide machine to form two symmetric sides 901 and 903. Each side 901 and 903 has two circuit board retention tabs 905, a handle pivot clearance hole 907, a bump 909, a bump spring relief area 911 and two circuit board guides 913. 
     As illustrated, each bump 909 is surrounded by a half semicircle spring relief area 911. This spring relief area allows the bump to flex inward as is required when the handle 101 is being moved between the handle open and the handle closed dimples. To assist in sliding the retaining clip 105 over a circuit board, the circuit board guides 913 are provided. These guides help center the clip relative to the leading edge of a circuit board making sliding the retaining clip onto the circuit board easy. 
     FIG. 9C is a side view and FIG. 9D is a sectional view of the retaining clip 105 taken along lines 9D of FIG. 9C. As is best illustrated in FIG. 9D, the circuit board retention tabs 905 are short stiff springs which flex inward to allow the clip to be inserted onto a circuit board. The clips 905 then engage reliefs in the circuit board thereby preventing the clips from coming off the circuit board. In addition, the clips 905 also transfer the extraction forces from the handle to the circuit board. 
     FIGS. 10A and 10B are front and rear isometric views of the handle 101 with the retaining clip 105 installed within the handle. The clip 105 is installed inside the handle by inserting the clip inside the handle such that the handle pivots 107 fit inside the handle pivot clearance holes 907. The clip is inserted inside the handle before the two sides 801 and 803 of the handle are bent together. Once the two handle sides 801 and 803 are bent into their final positions, the clearance between the ends of the two handle pivots 107 is such that the retaining clip can no longer be separated from the handle 101. To prevent galling of the metal handle by the full hard clip bumps, a suitable lubricant is used between the handle and retaining clip when they are assembled. 
     FIG. 10C is a side view and FIG. 10D is a sectional view of the handle and retaining clip assemble taken along lines 10D of FIG. 10C. In FIG. 10D the retaining clip 105 is illustrated retained inside the handle by the handle pivots 107. The gap 1001 between the ends of the handle pivots is sufficiently narrow to prevent the retaining clip 105 from separating from the handle 101. Each of the bumps 909 of the retaining clip 105 is illustrated seated inside the handle closed dimples 809 inside the sides 801 and 803 of the handle 101. 
     FIGS. 11A is a side view and FIG. 11B is a top view which illustrate the handle/clip assembly 1101 being inserted onto a circuit board 1103. The circuit board has reliefs 1105 formed in the circuit board and a pivot relief area 1107. Each of the circuit board reliefs 1105 are sized to engage the circuit board retention clips 905 which are part of the retention clip 105. As the handle/clip assembly 1101 is slid over the circuit board 1103, the circuit board retention clips 905 deflect until they are over the reliefs 1105. At that time the clips 905 spring inwardly thereby preventing the handle/clip assembly 101 from separating from the circuit board 1103. The pivot relief area 1107 guides the pivots 107 of the handle so that the handle/clip assembly is correctly positioned on the circuit board to allow the circuit board retention clips 905 to engage the circuit board reliefs 1105. They are also tapered for ease of assembly. 
     FIG. 11C is a side view and FIG. 11D is a top view of the handle 101 and clip 105 properly inserted onto the circuit board 1103. Once the handle/clip assembly 1101 is inserted onto the circuit board, the handle and clip assembly is fixed onto the board in a physically robust manner thereby insuring the insertion and extraction system will function reliably. Also, this novel handle attachment apparatus eliminates the screws, rivets and pins utilized in prior art designs which required a press or fixture on the manufacturing lines and the attendant attachment time by manufacturing line personnel. 
     FIG. 12A is a bottom isometric view and FIG. 12B is a bottom view of the HIF 109 shown here incorporated with the first card guide. This HIF is constructed of card cage metal and formed by a punch and die in the card cage manufacturing process. A card guide 113 is provided to guide a circuit board in a channel 1201 formed by two side walls 1203 and 1205. 
     As previously mentioned, if a short circuit board is to be mixed in a card cage with long circuit board, the HIF can be positioned after the card guide(s) 113. This allows the short circuit card to be guided into position by the card guide 113 and the HIF to be positioned as required (recessed inside the card cage) to insert and extract the short board from the electrical connectors inside the card cage. 
     Other embodiments of the invention will be apparent to the skilled in the art from a consideration of this specification or practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.