Structure for holding packages on backboard of electronics apparatus

Abstract: A package holding structure comprises a pair of linear guide members (11), secured on the package (2) along the respective edges thereof opposite to each other, and a pair of support members (10) for receiving the respective guide members (11), secured at one end thereof on the backboard (3) in a cantilever manner while projected vertically therefrom and having a connector housing (15) at the base end thereof for receiving a connector (14) on the package. The housing (15) has positioning apertures (13) to be fitted to contact pins (12) projected from the backboard (3).

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package holding system for holding packages on a backboard of an electronics apparatus such as a communication/information apparatus, in which a plurality of packages, each consisting of a printed circuit board mounting electronics devices thereon, are held in parallel to each other by a connector connection with a common backboard. 2. Description of the Related Arts Recently, a tendency toward a densifying of the mounting of a communication/information apparatus has been further accelerated by the development of an LSI technology and of an optical communication technology. The densified mounting tendency is not only for an electronics device in itself, but also for a package consisting of a printed circuit board on which such electronics devices are mounted. Accordingly, a prior art circuit structure requiring a large size printed circuit board can be accommodated in a smaller printed circuit board 1/2 or 1/3 of the former size. Generally, a larger size printed circuit board is preferable in view of the mounting efficiency and manufacturing costs, but in a communication/information system, a small size package consisting of a split printed circuit board is more preferable, to ease the affects of a machine failure and an initial investment burden on a customer. Therefore, recently an electronics apparatus has been proposed in which various size packages corresponding to the purpose thereof are assembled on a common backboard. In the conventional electronics apparatus in which same size packages are assembled, a common structure for accommodating such packages can be used, but an exclusive structure becomes necessary when accommodating various size packages in one apparatus, and thus problems arise of increased manufacturing costs and delayed deliveries. To solve these problems, as shown in Figs. 13(a) and 13(b), a holding structure for packages has been proposed, as in FR-A-2 371 855, which comprises a pair of upper and lower guide rails 1 fixed at a base end thereof on a backboard 3 by screws 4, the guide rails being spaced from each other by a distance corresponding to a size of a package 2 to be mounted to the backboard. The package 2 is introduced from an open space between the pair of guide rails 1, led along longitudinal grooves 5 formed on opposite sides thereof, and connected to pins projected from the backboard 3 by a connector fixed to the leading edge of the package 2. In this structure, however, the package 2 tends to move out of position due to a bending of the guide rails 1 when the weight of the package 2 is large. In addition, recently the number of pins has been increased, due to the high density mounting, and therefore, a larger force is required for an insertion/withdrawal of connectors connecting the package and the backboard, and thus a card lever must be provided on the package for carrying out the insertion/withdrawal operation. In this case, the guide rails are liable to be bent by a reaction to the force required for operating the card lever, and thus prevent a smooth insertion/withdrawal of the package. Another solution is provided as shown in Figs. 14(a) and 14(b), in which a plate-like accommodation frame 6 having a size corresponding to a package 2 to be mounted is prepared and fixed on a backboard 3 at the base end thereof by screws 4. A pair of upper and lower longitudinal grooves 5 are arranged on laterally extended rail portions 7 in upper and lower areas of the frame 6, opposite to each other, and the package 2 is introduced between the rail portions 7 along the grooves 5 into the frame 6, and connected to the backboard 3 by a connector. In this structure, the above problem regarding the bending inherent to the preceding conventional structure is solved because the frame 6 integrally interconnects the upper and lower rail portions. Nevertheless, this structure has drawbacks in that a height of electronics devices and mechanical parts mounted on the package is limited, whereby the freedom of design is lowered, and in that various exclusive accommodation frames are necessary for respective packages having different sizes. Further, as a drawback common to these two prior arts, it is difficult to coincide the position of a connector on the package with that of a connector housing on the backboard. A primary reason for this resides in dimensional errors in an assembly of the holding structure, because the connector housing and the guide rails are manufactured as separate parts. A secondary reason resides in a higher variance in the thickness of printed circuit boards, compared to the manufacturing tolerance of other parts, whereby in the course of the assembly of packages on the backboard, the positions of the connectors of the respective printed circuit boards arranged vertical to the common backboard tend to vary as the thickness of the printed circuit board varies, if an erroneous reference plane is selected during the introduction of the package along the guide rails. SUMMARY OF THE INVENTION Accordingly, the object of the present invention is to solve the above drawbacks of the prior arts and provide a package holding system in which varioussized packages can be smoothly mounted without vacant spaces therebetween, which structure is formed by the provision of a minimum number of standard structural parts on the backboard. The above object is achieved, according to the present invention, by a package holding system for supporting packages on a backboard in an electronics apparatus, said system comprising a package holding structure and at least a package having a rectangular shape and having a connector on one surface along the rear edge thereof, said backboard being positioned perpendicular to the package or packages and having rows of contact pins projected therefrom such that the connector on a package and the contact pins on the backboard can be fitted with each other to form an integral body, said package holding system further comprising: a pair of linear guide members, secured on a package along the respective edges thereof opposite to each other and perpendicular to the edge on which the connector is mounted, having a lengthwise groove with a pair of inner walls for receiving the corresponding edge of the package, and fixed to the package while one of the inner walls of the groove is tightly in contact with the connector-mounting surface of the package; and a pair of support members for receiving the respective guide members, secured at one end thereof on the backboard in a cantilever manner and projected perpendicularly therefrom, while being intervened between by the rows of contact pins, having a slide groove with a cross-section and dimension allowing only a lengthwise movement of the linear guide member but preventing other directional movements thereof, and a connector housing at the base end thereof for receiving the connector on the package, having positioning apertures to be fitted to corresponding part of the contact pins. The package holding system according to the present invention is operated as follows: When assembling the electronics apparatus, the pair of support members are positioned on the backboard so that a distance between the support members corresponds to a height of the package to be assembled, and are fixed thereto while fitting the positioning apertures on the connector housing to the corresponding contact pins on the backboard. The package is prepared by fixing the pair of linear guide members along the opposite edges of the package while one of the inner walls (hereinafter referred to as a "reference surface") of the lengthwise groove is tightly in contact with the connector-mounting surface of the package. Accordingly, the height of the connector protruded above the reference surface is constantly kept accurate regardless of thickness variations of the printed circuit board of the package. The package is introduced from the free ends of the pair of support members into a space therebetween, and accurately guided toward the backboard along the slide grooves without lateral vibration. At the end of this insertion stroke, the connector on the package is properly fitted in the connector housing on the backboard and engaged with the contact pins, and thus the support member is associated with the mated support member via the linear guide members and the package, whereby a strong connection of the package with the backboard is obtained while maintaining an accurate positional relationship between the respective parts. The package holding system of the present invention can be such that the backboard consists of a first backboard and a second backboard, arranged in parallel to each other, both backboards being rigidly connected by contact pins pierced therethrough to form an integral body with a distance between said backboards. BRIEF DESCRIPTION OF THE DRAWINGS The other objects and further advantages of the present invention will be more apparent with reference to the preferred embodiments illustrated in the attached drawings: wherein Figure 1 is a perspective view illustrating a structure of support members and a backboard forming part of the system of the present invention; Figure 2 is a cross-section of the support member along lines I-I of Fig. 1; Figure 3 is a perspective view illustrating a structure of linear guide members and a package in the system of the present invention; Figure 4 is a cross-section illustrating the positional relationship between the linear guide member and the package; Figure 5 is a perspective view of the package relative to the support members at a midway point of the insertion stroke; Figure 6 is a side sectional view of the package when the insertion stroke is completed; Figure 7 is a perspective view of a first arrangement using the package holding system according to the present invention; Figure 8 is a front view of the arrangement shown in Fig. 7; Figure 9 is a perspective view of a second arrangement using the package holding system according to the present invention; Figure 10 is a front view of the arrangement shown in Fig. 9; Figure 11 is a perspective view of a third arrangement using the package holding system according to the present invention; Figure 12 is a perspective view of a fourth arrangement using the package holding system according to the present invention; Figures 13(a) and 13(b) respectively, a side view and a cross-section view taken along the line A-A of a conventional package holding structure; Figures 14(a) and 14(b) respectively, a side view and a cross-section view taken along the line B-B are of another conventional package holding structure; Figure 15 is a perspective view of an electronics apparatus having a backboard structure according to the system of the present invention; Figure 16 is a partial enlarged sectional view of the backboard structure shown in Fig. 15; Figure 17 is a sectional view illustrating a fastening of a connector housing on a backboard by a short contact pin; Figure 18 is a perspective view of a long contact pin for connecting first and second backboards; Figure 19 is a sectional view illustrating a fastening of a connector housing on a backboard by a long contact pin; Figure 20 is an exploded view of another embodiment of the backboard structure according to system of the present invention; Figure 21 is a partial enlarged view of the backboard structure shown in Fig. 20; and Figure 22 is a sectional view of the assembled backboard structure shown in Figs. 20 and 21. DESCRIPTION OF THE PREFERRED EMBODIMENTS Package Holding Structure A package holding system, according to the present invention, for supporting a package, comprises a pair of support members 10, 10 fixed to a backboard 3 (see Fig. 1) and a pair of linear guide members 11, 11 fixed to a package 2 (see Fig. 3). As shown in Fig. 1, the support member 10 is a molded plastics part having a substantially U-shaped cross-section and a short edge portion 10a and a long edge portion 10b intersecting each other at a right angle; another supporting member having a shape symmetrical thereto is combined as a mating member, to form a pair. In a back wall of the short edge portion 10a is formed a plurality of positioning apertures 13 engageable with rows of contact pins 12 arranged on a predetermined area of the backboard 3. The short edge portion 10a also forms a housing 15 for receiving a connector 14 secured on the package. In a bottom wall of the long edge portion 10b are formed ventilation openings 21 along the whole length thereof, for cooling a heat generated from electronics devices mounted on the package. A slot 17 is provided at the tip end of the long edge portion 10b and receives a projection 16a of a card lever 16 described later. As shown in Fig. 2, a laterally protruded longitudinal rib 18 extends along the whole length of inner edge of one of the side walls of the long edge portion 10b. The respective support members 10, 10 of this pair are arranged on the backboard 3 in such a manner that a back wall of the short edge portion 10a is in parallel to the backboard 3 and the open sides of the U-shaped cross-section of the respective long edge portion 10b are opposite to each other while the distance therebetween is kept at a value corresponding to a height of the package 2, and fixed in place on the backboard 3 by screws or rivets 19 to thus project from the backboard 3 in a cantilever manner, while engaging the positioning apertures 13 with the rows of contact pins 12. As shown in Fig. 3, the linear guide member 11 is a molded part of plastics having a length corresponding to that of package 2. On one side surface of the guide member 11 is provided a groove 20 for mounting the package with an inner width wider than the wall thickness of the package 2, along which mountings 23 for rivet are arranged at a proper pitch. In the bottom wall adjacent to the mountings 23, ventilation openings 21 similar to the openings 21 of the support member are formed along the whole length thereof. A resiliently deformable lock arm 22 is formed at a tip end of the linear guide member 11 and operates in association with the card lever 16. The linear guide member 11 is mounted on the package 2 along a pair of edges thereof vertical to the edge to which the connector 14 is arranged, i.e., the guide member 11 is inserted into the groove 20 and fixed by the rivet 24 laterally through the mountings 23 on the package 2. It is important that, due to the rivet fastening as stated above, the connector-mounting surface A of the package 2 can be tightly in contact with the inner wall P of the groove 20 as illustrated in Fig. 4, whereby a distance d between the inner wall p (referred to as a "reference surface") and the top surface of the connector 14 is always kept constant regardless of considerable thickness variations in the printed circuit board of the package 2 due to the lower manufacturing tolerance thereof. This is one of the conditions for the smooth engagement between the connector 14 and the contact pins 12 on the backboard. A front plate 25 is attached along the whole length of a front edge of the package 2, and a pair of card levers 16 are secured at the opposite ends of the front edge for carrying out the insertion/withdrawal of the package. A slide groove 26 extends beneath the rib 18 lengthwise of the long edge portion 10b. The slide groove 26 is formed to have an accurate height h and an inner width w (see Fig. 2) so that it can receive the linear guide member 11 having a height g and an outer width u (see Fig. 4) without a play therebetween but with a smooth slidability. A tip end 11a of the linear guide member 11 is chamfered. When the package 2 is mounted at the predetermined position on the backboard 3 and connected to the latter by the connector, the linear guide members 11 fixed to the upper and lower edges of the package 2 are introduced to the pair of support members 10 projected in a cantilever manner from the backboard 3. Then both the members 10, 11 are smoothly engaged with each other due to the above dimensional relationships and the shape of the tip end of the guide member 11, and guide member 11 can slide in the lengthwise direction but any up-down fluctuation thereof is inhibited by the rib 18 of the support member 10. A state thereof at a midway point of the insertion stroke is illustrated in Fig. 5. This insertion of the package is carried out with a highly accurate engagement between the slide groove 26 of the support member 10 and the linear guide member 11, and the connector 14 on the package 2 is correctly received by the housing 15 on the backboard 3 so that it can be connected with the contact pins 15. When the insertion of the package 2 has been completed, the projection 16a of the card lever 16 is fitted into the slot 17, and simultaneously, a latch 22a of the lock arm 22 is caught by an edge of the ventilation opening 21 to lock the package 2 in place, as shown in Fig. 6. As stated above, when the upper and lower support members are connected with each other through the package, with the linear guide members, the rigidity of the support members is increased compared to that obtained when the respective support member is engaged with the package without the linear guide member, whereby the package holding function of the support member is enhanced. Figures 7 and 8 illustrate a first arrangement based on the above-stated principle of the present invention, in which several kinds of packages having a size different from each other are mounted on a common backboard so that the respective support member is positioned at a minimum lateral pitch, i.e., without any vacant space between adjacent packages. Figures 9 and 10 illustrate a second arrangement in which the support members are positioned at optional lateral pitches. Figure 11 illustrates a third arrangement in which a package holding system according to the present invention is applied to a casing, such as a shelf, for accommodating different sized packages. Figure 12 illustrates a fourth arrangement in which a plurality of assemblies of backboard and packages having different sizes and formed in a manner similar to the first and second arrangements are stacked in a cabinet rack. In conclusion, according to the present invention, the package can be effectively arranged at a desired position on the backboard, and thus this can be applied to current electronics apparatuses which required a very dense mounting. Also, this results in an improvement of the productivity as well as a lowering of total cost of the electronics apparatus. More specifically, a support member is reinforced by the engagement of the linear guide member with a groove of the support member when the package is introduced between upper and lower support members. Accordingly, even if the ventilation opening is formed on the support member, this does not affect the rigidity of the support member. For the same reason, the support member can have a thinner wall and/or a longer wall. The support member has sufficient rigidity to withstand a reaction generated when the card lever is actuated, and thus there is no positional deflection of the support member due to a deformation thereof. As one inner side wall of the groove of the linear guide member is in close contact with the connector-mounting surface of the package when the linear guide member is fixed on the package, the mounting accuracy of the connector is improved regardless of thickness variations of the printed circuit board, and accordingly, the connector can be smoothly connected with the pins on the backboard. As the support member itself has a function for guiding the package and for accommodating the connector, and is provided with positioning apertures for a direct engagement with the contact pins on the backboard, an accurate connection between the package and the backboard through the connector is obtained. Backboard Structure According to the above package holding structure, the backboard is preferably reinforced, to thus be able to withstand the additional weight of the support member and the linear guide member, as well as the force needed for connecting the connector with the increased number of pins. As shown in Figs. 15 and 16, according to this embodiment, a backboard is separated into a first backboard 3a for the interconnection between packages 2 arranged on the backboard and a second backboard 3b for the connection between the backboard and outer circuits. As usual, rows of short contact pins 12 are implanted in the first backboard 3a and connected to printed circuits built-in to the backboard 3a. As described before, a housing 15 of a support member 10 is fixed on the first backboard 3 by press-fitting the short contact pins 12 into positioning apertures 13 of the housing 15 (see Fig. 17). The second backboard 3b is arranged outside of the first backboard 3a and in parallel thereto, with a distance therebetween. In this embodiment, the second backboard 3b has half the height of the first backboard 3a. The upper edge of the second backboard 3b carries a series arrangements of a plurality of interface connectors 31 to which cables 32 from the outer circuit are introduced. In the lower region of the backboard 3b beneath the interface connectors 31 are implanted a plurality of long contact pins 33, which penetrate the first backboard 3a through apertures 34 and project from the inner surface of the first backboard 3a. The long contact pins 33 are connected with the interface connector 31 through printed circuits built-in to the second backboard 3b. As shown in Fig. 18, the long contact pin 33 has a wider central portion 33a which acts as a spacer for maintaining a predetermined distance between the backboards 3a, 3b. As shown in Fig. 19, the tip end of the long contact pin 33 projecting from the first backboard 3a is also press-fitted to the positioning aperture 13 provided on the back wall of the housing 15, through an aperture 13' formed on the first backboard 3a. According to this arrangement, the outer circuits are connected with the respective package 2 when the connector 14 is engaged with the housing 15. To further improve the rigidity, a horizontal reinforcement member 40 is provided between the first backboard 3a and the second backboard 3b, along the upper and lower edges of thereof. In this connection, to clarify the drawing, the upper reinforcement member is omitted in Fig. 20 and only the lower reinforcement member is illustrated. The reinforcement member 40 consists of a base plate 41 and a rib 42 protruded upward therefrom. The rib 42 has a lengthwise recess 43 with a triangular cross-section in the front wall thereof. The backboards 3a and 3b are positioned on the opposite edge regions of the base plate 41 while sandwiching the rib 42 therebetween. As stated before, the support member 10 is mounted on the predetermined position of the first backboard 3a, for introducing the package 2, and the support member 10 has a screw hole 45 on the base thereof. A vertical spacer element 46 is arranged between the upper and lower reinforcement members 40 at a position corresponding to that of the support member 10. The spacer element 46 is made of rigid plastics and has a constant thickness d, except for the upper and lower end region having an abutment 47 with a special cross-sectional shape. A notch 48 is formed in the abutment 47. As shown in Fig. 21, the arcuate rear surface of the abutment 47 is engaged with the lengthwise recess 43 of the reinforcement member 40 when positioned in place. This state will be described below in more detail with reference to Fig. 21. A rib 42 has a flat and vertical rear wall 42a closely in contact with the first backboard 3a. Also, the spacer element 46 has a flat and vertical front wall 46a to be closely in contact with the second backboard 3b. The front end of the abutment 47 projects forward from the front wall 46a of the spacer element 46 by a distance δ. A screw 49 is pierced from the second backboard side through the respective members thus positioned in place. The tip end of the screw 49 projected from the first backboard 3a via the notch 48 is threadedly engaged with a screw hold 45 on the support member 10, to rigidly fasten the respective members together to form an integral assembly. The above distance δ allows the resilient deformation of the abutment 47 during this fastening by a screw 49, so that the fastening force is increased. The assembled state thus obtained is illustrated in Fig. 22. Reference signs in the claims are intended for better understanding and shall not limit the scope.

Claims: A package holding system for supporting packages on a backboard in an electronics apparatus, said system comprising a package holding structure and at least a package having a rectangular shape and having a connector on one surface along the rear edge thereof, and a backboard positioned perpendicular to the packages and having rows of contact pins-projected therefrom such that the connector on the package and the contact pins on the backboard can be fitted together to form an integral body, said package holding system further comprising: a pair of linear guide members (11), secured on the package (2) along the respective edges thereof opposite to each other and perpendicular to the edge on which the connector (14) is mounted, having a lengthwise groove (20) with a pair of inner walls for receiving the corresponding edge of the package (2), and fixed to the package (2) while one (P) of the inner walls of the groove (20) is tightly in contact with the connector-mounting surface (A) of the package; and a pair of support members (10) for receiving the respective guide members (11), secured at one end thereof on the backboard (3) in a cantilever manner and projected perpendicularly therefrom, the rows of contact pins (12) intervening between the support members (10), each having a slide groove (26) with a cross-section and dimension allowing only a lengthwise movement of the linear guide member (11) but preventing other directional movements thereof, and a connector housing (15) at the base end thereof for receiving the connector (14) on the package, having positioning apertures (13) to be fitted to corresponding part of the contact pins (12). A package holding system as defined by claim 1, wherein the linear guide member (11) and the support member (10) have a ventilation opening (21) for cooling the package (2). A package holding system as defined by Claim 1, wherein a card lever (16) having an operating projection (16a) is secured on the front edge of the package (2) and a slot (17) engageable with the projection (16a) is provided in the front end area of the support member (10). A package holding system as defined by Claim 3, wherein a resiliently deformable lock arm (22) having a latch (22a) engageable with the ventilation opening (21) of the support member (10) when the package (2) is fully inserted into the support members (10) is formed in the front end area of the support member (10) and associated with the card lever (16). A package holding system as defined by any of Claims 1 to 4 wherein the backboard (3) consists of a first backboard (3a) and a second backboard (3b) arranged in parallel to each other; both backboards (3a, 3b) being rigidly connected by contact pins (33) pierced therethrough to form an integral body, with a distance between said backboards. A package holding system as defined by Claim 5, wherein a pair of horizontal reinforcement members (40) is arranged between the first backboard (3a) and the second backboard (3b) along the upper and lower edges thereof, and a vertical spacer element (46) is arranged to bridge the upper and lower reinforcement members (40) at a position corresponding to that of the connector housing (15) of the support member (10) on the backboard (3a); the support member (10), the first backboard (3a), the horizontal reinforcement member (40), the vertical spacer element (46) and the second backboard member (3b) being integrally assembled together by a screw (49) pierced therethrough and fastened to the connector housing (15) positioned on the first backboard (3a).

Inventors: KANNO TAKASHI, TAKAHASHI TSUTOMU, ZENITANI HIDEKI, KANNO, TAKASHI, TAKAHASHI, TSUTOMU, ZENITANI, HIDEKI
Applicants: FUJITSU LTD, FUJITSU LIMITED
Application year: 1991
Main classification: H05K7
IPC codes: H05K7