WO2003092346A1

WO2003092346A1 - Board injector/extractor

Info

Publication number: WO2003092346A1
Application number: PCT/SE2002/000836
Authority: WO
Inventors: Karl Gunnar Malmberg; Kaj Tommy NÄSSTRÖM
Original assignee: Telefonaktiebolaget Lm Ericsson
Priority date: 2002-04-26
Filing date: 2002-04-26
Publication date: 2003-11-06
Also published as: AU2002307610A1

Abstract

An electronic subassembly (20) is provided having an injector/extractor device (1) that during subassembly injecting operation thereof builds up a contact force between the subassembly and a supporting chassis (30) and that is locked in a subassembly injected position, to continuously apply said contact force in the locked position (C). The contact force is built up by supporting a pivot axis (PA) of a lever (2) of the injector/extractor so that it is displaceable against a biasing force and by providing integrated locking means (5, 13) securely locking the lever in the contact force application position. Accordingly, the invention eliminates the need for separate fasteners to apply the contact force, thereby not only essentially facilitating the injection/extraction procedure but also simultaneously saving the cost of prior art nut receiving channels in the chassis.

Description

TITLE: BOARD INJECTOR/EXTRACTOR

TECHNICAL FIELD

The present invention relates to the injection/extraction of electronic subassemblies into and from a supporting host chassis, respectively, and specifically concerns the electrical connection of such subassemblies.

BACKGROUND

In electronic systems employing a multitude of electronic components or electronic modules, it is common to accommodate electronic subassemblies such as printed circuit board or card modules in a supporting chassis. An example of this is found in telecommunication systems, where it is conventional to accommodate several such subassemblies in supporting sub-racks within a cabinet. The PCB-modules are manually inserted into the corresponding sub-rack, with their side edges guided in board guides attached to the racks. Thus, the modules are manually pushed in until they approximately reach a position of electrical connection of the module to the back-plane of the sub-rack. This electrical connection is established by means of mating connectors on the back-plane and on the module inner edge, respectively. Quite considerable connector forces will have to be overcome in order to complete and release, respectively, the electrical connection, and to this end, it is common to use injecting/extracting devices to facilitate the application of the required injection/extraction forces.

Such injecting/extracting devices conventionally consist of a base that is secured to a PCB or more commonly to a front plate of a PCB-module, and that pivotally supports a lever. The lever in turn has an engagement means. During the final injection of the module through the pivoting of the lever its engagement means engages a corresponding abutment on the sub-rack to force the module into the fully connected position, overcoming the connector forces. After the complete injection of the module, specific measures must be taken to secure appropriate grounding contact also between the board or board front and the back-plane. Such contact is vital to the appropriate operation of the system, both with regard to the fact that grounding or earth-connecting of the module or board is mostly performed through this contact and to the fact that it is important to provide effective shielding against electromagnetic radiation that may otherwise disturb and interfere with the operation of adjacent modules. This vital contact is normally secured by applying an appropriate contact force between mutually engaging contact surfaces of the board module and the back-plane. Such a contact force must be also be sufficient to compensate for any tolerances between the two elements and is normally generated by means of screw fasteners. Upon completion of the injection of the module and the electrical connection thereof at the back-plane screw fasteners are inserted through apertures in the board front and in a supporting outer surface of the sub-rack. Finally, the screw fasteners are brought into engagement with nuts that are secured against rotation in a nut receiving channel attached to the sub-rack, and are tightened to apply the required contact force. When a module is to be removed the fasteners at each side of the module must first be loosened and removed.

The described conventional method of securing the appropriate contact force is very unsatisfactory in the respect that it is time consuming and troublesome, especially in a laboratory where system components are tested and the modules have to be replaced frequently. An additional specific problem occurs in the event that one of the screw fasteners breaks as it is tightened. In such a case, the entire magazine may have to be disassembled.

SUMMARY

The invention overcomes the above problems in an efficient and satisfactory manner.

A general object of the invention is to provide a solution to the problem of facilitating the application of a contact force between an injected electronic subassembly and a receiving chassis, that is sufficient to secure the required grounding and electromagnetic shielding.

In particular, it is an object of the invention to provide an improved electronic subassembly that eliminates the need for separate fastening means for providing the appropriate grounding and shielding contact between the subassembly and the chassis.

Briefly, the above object is achieved by means of an electronic subassembly having an injecting/extracting device that during subassembly injecting operation thereof builds up a contact force between the subassembly and the chassis and that is locked in a subassembly injected position, to continuously apply said contact force in the locked position. Specifically this is achieved by supporting a pivot axis of the injector/extractor lever so that it is displaceable against a biasing force and by providing integrated locking means securely locking the lever in the contact force application position. Accordingly, the invention eliminates the need for separate fasteners to apply the contact force, thereby not only essentially facilitating the injection/extraction procedure but also simultaneously saving the cost of the prior art nut receiving channel in the chassis.

By allowing the pivot axis to be displaceable generally normal to the board front, the optimum transfer of the biasing force to the board front is achieved.

In a practical embodiment of the invention a floatingly supported pivot carries the lever, and a biasing means acts between the pivot and body, urging the pivot away from the board front. The biasing means preferably applies continuos biasing force to the pivot to urge the latter towards a fixed end position.

In a further practical embodiment of the invention, the pivot is displaceably supported in elongate openings in the body.

In order to facilitate the engagement between the lever and the sub-rack engagement formation it is likewise advantageous if the pivot is floatingly supported also in the lever, with the pivot being displaceable in elongate openings in the lever. To secure the build-up of a sufficient contact force the openings in the lever are arranged so that they form an angle with the openings of the body.

In further practical embodiments of the invention, complementary locking means are provided, being secured to the board front and to the lever respectively, and/or the biasing means is a leaf spring fixed to the body of the injector/extractor. To obtain a simple and inexpensive manufacturing, the body of the injector/extractor may preferably be an integral steel plate unit formed in one piece with a locking means and biasing means.

The lever is pivotal between an inactive position being disengaged from the formation on the chassis and an injection position where it engages the formation to fully inject the electronic subassembly into a connected position in the chassis. Thereby the subassembly is continuously pushed into its fully connected position by the biasing force when the lever is in its locked position.

Another object of the invention is to provide an improved electronic subassembly injecting/- extracting device that solves the problem of applying a contact force between a subassembly and a supporting chassis.

A further object of the invention is to provide an improved and very time saving method of applying a contact force between an electronic subassembly and a supporting chassis.

These and further objects of the invention are met by the invention as defined in the appended patent claims.

Advantages offered by the present invention, in addition to those described above, will be readily appreciated upon reading the below detailed description of embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS The invention, together with further objects and advantages thereof, may best be understood by referring to the following description taken together with the accompanying drawings, in which:

Fig. 1A is a partial schematic perspective view of a circuit board module according to the invention in a locked position in a supporting chassis;

Fig. IB is a plan view from one side of a first embodiment of an injector/extractor as employed on the board module of fig. 1 A and illustrated in an unlocked condition;

Fig. 2A is a side view of a body part of the injector/extractor illustrated in fig. IB;

Fig. 2B is a bottom perspective view of the body illustrated in fig. 2 A; Fig. 2C is a top perspective view of the body illustrated in fig. 2 A;

Fig. 2D is a top plan view of the body illustrated in fig. 2 A;

Fig. 3 A is a side view of a lever part of the injector/extractor illustrated in fig. IB;

Fig. 3B is a bottom perspective view of the lever illustrated in fig. 3 A;

Fig. 3C is a top perspective view of the lever illustrated in fig. 3 A;

Figs. 4A is a partial cross section through a host chassis during injection of a an embodiment of a board module according to the invention, being provided with injectors/extractors as illustrated in fig. IB;

Figs. 4B is a partial cross section through the host chassis of fig. 4 A during a first stage of the actual locking of the board module to the chassis by means of the in- j ectors/extractors;

Figs. 4C is a partial cross section through the host chassis of fig. 4A after completed locking of the board module to the chassis by means of the injectors/extractors;

Fig. 5 A is a side view of a modified embodiment of an injector/extractor according to the invention illustrated in a locked condition;

Fig. 5B is a top perspective view of the lever of the injector/extractor illustrated in fig. 5A;

Fig. 5C is a top perspective view of the injector/extractor body illustrated in fig. 5 A;

Fig. 6 is an end view of a further embodiment of the injector/extractor lever;

Fig. 7 is a side view of a modified embodiment of an injector/extractor body according to the invention. Fig. 8 is a top plan view corresponding to fig. 2D illustrating a further embodiment of the invention, providing an alternative way of axially positioning the pivot pin; and

Fig. 9 is a very schematic and partial view of a modified embodiment of the invention intended for use in an application where the board module "bottoms" at the backplane.

DETAILED DESCRIPTION OF EMBODIMENTS

A first embodiment of the invention will now be described with specific reference to drawing figures 1A-B, 2A-D and 3A-C. Fig. 1A schematically illustrates an embodiment of an electronic subassembly 20 according to the invention in a position where it has been injected into and locked in position in a supporting chassis 30. In the illustrated embodiment, the electronic sub- assembly 20 is a circuit board module 20 of the snap-in type commonly used in many areas, such as in the telecommunications industry. In such applications an optional number of PCB-modules 20 are received in a supporting chassis 30. The board modules are guided into position in the chassis 30 by separate board guides 34 (see fig. 4A-C) and are electrically connected at a backplane 39 (see fig. 9) of the supporting chassis.

The illustrated circuit board module 20 consists of a printed circuit board 21 having a board front 22 with connector sockets 23 secured to an outer edge 26 thereof. Adjacent each side edge 28 of the circuit board 21 the board front 22 carries a device 1 that is used to perform final insertion and initial ejection, respectively, of the board module 20 into and from the chassis 30, respectively. Such devices 1 are generally well known within the art and are referred to in this specification as injectors/extractors 1. The electrical connection of the board module 20 is established by means of complementary connector parts 29, 35 supported on an inner edge 27 of the board module 20 and on the back-plane 39 (fig. 9) of the chassis, respectively. Such connectors 29, 35 are well known in several configurations within the art and have therefore not been illustrated in any detail in the drawings. Although fig. 1A illustrates a condition where the board module is fully injected and locked to the chassis, the connector pairs 29, 35 are illustrated in a separated position for reasons of clarity. The board module 20 is inserted with its side edges 28 into the appropriate board guides 34 of the chassis

30. Then the board module 20 is pushed in to a position where injectors/extractors 1 can be brought into engagement with complementary fixed engagement means 32 on the chassis to perform the final injection establishing electrical connection.

In the embodiment of fig. 1A the very schematically illustrated chassis 30 is a sub-rack of the kind that is used i.e. in telecom cabinets (not illustrated) and that commonly consists of steel plates 33 that are perforated to provide access for cooling air to the heat generating board modules 20. Along an outer side of those chassis or sub-rack plates 33 that carry board guides 34 (see fig. 4A-C) is provided an elongate rail or bar 31 having an engagement means 32 in the form of a generally hook-shaped engagement formation 32 at its outer long side. As was mentioned briefly above, the purpose of this engagement formation 32 on the rail 31 is to serve as a fixed abutment for the injectors/extractors 1 during their final injection of the board modules 20 to the fully connected position, as well as during their initial extraction from said connected position. This will be discussed further below in connection with figs. 4A-C.

The injectors/extractors 1 that are secured to the respective ends of the board front 22 of fig. 1 A are identical but are turned so that they face away from each other to engage the respective engagement formation 32 on opposite sub-rack plates 33. An embodiment of such an injector/extractor or injecting/extracting device 1 of the invention is illustrated on an enlarged scale in fig. IB, and the constituent parts thereof are illustrated in figs. 2A-D and 3A-C. In fig. IB, the injecting/extracting device 1 is illustrated in an open non-active position (position A in the later discussed fig. 4A) thereof. The injector/extractor 1 of the invention consists of a body 10 in which a lever 2 is pivotally supported by means of a pivot pin 9 forming a pivot axis PA for the lever 2. The body 10 is preferably secured to the board front 22 with a base 16 thereof bearing flat upon an outer surface of the board front. It is secured to the board front 22 such as by means of a screw fastener 18 that is inserted through an aperture 17 (fig. 2B) in the base 16 and that is screwed into a threaded bore (not illustrated) in the board front 22.

In accordance with the invention, the pivot axis PA of the lever 2 is floatingly supported in the body 10. In the illustrated embodiment this is accomplished by positioning the pivot pin in elongate openings 12 in the respective, spaced side walls 14, 15 (see especially figs. 2B-D) of the body 10. The elongate openings 12 are extended in a direction being generally normal to the base 16 of the body 10 and thus also to the outer surface of the board front 22 in the assembled condition. This floating support permits displacement of the pivot pin 9 and thereby of the pivot axis PA of the lever 2 in a direction that is likewise substantially normal to the base 16 of the body 10 as well as to the board front 22. In accordance with a further basic feature of the invention the pivot axis PA is also continuously biased for movement in a direction generally away from the base 16 of the body 10 and thus from the board front 22. The biasing force constantly urges the pivot axis PA/the pivot pin 9 towards an end position engaging the upper end of the elongate openings 12.

In this embodiment, the biasing force is applied through a biasing means in the form of a spring 11 acting directly upon the pivot pin 9. Here, the spring 11 acts directly between the base 16 of the body 10 and the pivot pin. In fact, in the embodiment of figs. 2A-D the spring 11 is formed integral with the base 16 of the body 10. The entire body 10 is formed in one piece of an appropriate steel plate material that is bent to provide the leaf spring 11, the side walls 14, 15 and a generally latch-shaped locking means 13. The body locking means 13 co- operates with a complementary lever locking means 5 to lock the lever in a position (position C in fig. 4C) where it engages the sub-rack formation 32 under simultaneous displacement of the pivot axis PA against the biasing force. The body locking means 13 is resiliently yieldable in order to allow the lever locking means to enter the locking position, as will be explained below.

The leaf spring 11 applies a biasing force that may vary for different standards and applications. As an example an adequate biasing force for a secure connection of a telecom cabinet PCB- module 20 to a corresponding sub-rack may equal that applied by a conventionally used screw fastener. Specifically, it is desirable to apply a force that is at least in the same order as that applied by an M 2.5 screw tightened with 0.5 Nm.

The lever 2 of the injecting/extracting device 1 is illustrated in detail in figs. 3A-C and is of a design that is generally known within this field. Thus, the lever 2 has a top wall 8 that in this embodiment is continuous to provide the required strength. From each long side of the bottom wall is extended a side wall 6, 7. Said side walls 6, 7 are spaced apart so that they in the assembled condition straddle the side walls 14, 15 of the body 10. The lever 2 is preferably formed in one piece from an appropriate material, i.e. it may be cast from a plastic material or, in applications where cold flowing may present a serious problem, it may be cast from a metallic material or may even be formed from a steel plate bent to the appropriate shape.

In the illustrated embodiment, the pivot pin 9 is not only floatingly supported in the body 10 but also in the lever 2. Specifically, the pivot pin 9 is likewise received in elongate openings 4 in the lever 2 side walls 6, 7. This configuration of the lever 2 is known per se, and the main purpose thereof is to facilitate engagement of the lever 2 with a sub-rack engagement formation 32 having the configuration illustrated in fig. 1 A. The openings 4 in the lever side walls 6, 7 are positioned so that they form an angle with the elongate openings 12 of the body, at least in the fully locked position (angle in the position C in fig. 4 C) of the injecting/extracting device 1. This will be described further below. In this embodiment, with the pivot pin 9 being floatingly supported in the body 10 as well as in the lever 2, retaining rings 19 (one schematically illustrated in fig. IB) or any other appropriate means are preferably provided in order to secure that the pivot pin 9 does not accidentally fall out from its position therein.

At one end of the lever 2 engagement means 3 are formed in the side walls 6, 7. Said engagement means 3 are formed as cut-outs in the side walls 6, 7 and they are sized so as to grasp the sub-rack engagement formations 32 during the final insertion of the electronic subassembly 20, in the locked and fully connected condition as well as during extraction. Finally, the lever is provided with a generally latch-shaped locking means 5 that is complementary to the body locking means 13 to cooperate with the latter to securely lock the lever 2 to the body 10 in the fully connected position (position C in fig. 4C). In this embodiment, the lever locking means 5 is formed integral with the lever 2 adjacent an inner surface of the top wall 8 of the lever 2. However, the lever locking means may also be in the form of a separate member that is attached to the lever 2.

The operation of the described embodiment of the invention will now be explained with specific reference to figs. 4A-C. As mentioned above, a PCB module 20 is manually inserted into a sub- rack 30 with its side edges 28 (fig. 4B) guided in the schematically illustrated board guides 34. During this insertion of the module 20 in the direction ID the injector/extractor levers 2 are maintained in their open position A, pivoted clockwise to the right in fig. 4A. In this position, the spring 11 that applies a continuous biasing force to the pivot pin 9 displaces the pin and the pivot axis PA so that the pin is urged against the upper end of the elongate groove 12 in the body 10.

The manual insertion or pushing-in of the PCB module 20 in the direction ID continues approxi- mately until it reaches a position where contact pins (not shown) of the board connectors 29 are about to enter the corresponding sockets 36 of the backplane connectors 35 (see fig. 1A). In this position, the engagement means 3 of the lever 2 have already reached a position where they engage the sub-rack formation 32 through simultaneous anti-clockwise rotation thereof. As was mentioned above, the provision of the elongate groove 4 in the lever 2 facilitates such engage- ment. The engagement between the lever 2 and the sub-rack formation 32 causes the lever to rotate about engagement point EP (fig. 4B) upon further maneuvering thereof. This will cause the pivot pin 9 to be displaced downward in the elongate openings 12 of the body 10 to cause compression of the spring 11 and thereby an increase of the biasing force thereof. Since the manually applied force is maintained against the lever 2 this increased biasing force will be transferred to the board module 20 to overcome the resistance of the connector sockets 36 to the insertion of the board connector pins in a first connecting sequence. This sequence is illustrated by fig. 4B showing the lever 2 in a position B where its locking means 5 is about to force the body locking means 13 to bend away elastically.

During the further rotation of the lever 2 around the engagement point EP to the locked position C illustrated in fig. 4C, the pin 9 is moved further down in the opening 12 and the biasing force continues to increase. In the locked position C the body locking means 13 gets free from the lever locking means 5 and springs back to grip behind the former and to lock the lever 2 against any clockwise rotation caused by the spring 11 biasing force. In this second sequence, as the module enters the sub-rack 30, the increased biasing force is sufficient to overcome the contact forces of contact springs 24 (see fig. 1 A) on the board front 22 and of grounding springs 25 that in some applications are provided on the board front 22, at its contact surface with a sub-rack support surface 38 (fig. 1A). Alternatively, corresponding grounding springs 25 may be provided on the outer support surface 38 of the sub-rack. In this manner the lever 2 is locked in a position C where it indirectly, through the transfer of the biasing force of the spring 11 to the board module 20, automatically and continuously applies a contact pressure between the board front 22 and the sub-rack 30. As was mentioned above, the applied contact pressure should at least approximately equal that applied by a conventionally used screw fastener. During injection of the board module 20, guide pins 22B on the board front are normally inserted into apertures 37 in the outer support surface 38 of the sub-rack 30 to position the board front correctly therein.

For the extraction of the board module 20 from the sub-rack 30 the lever 2 is lifted in its free end opposite the engagement means 3, possibly in combination with a slight further compression of the spring 11. This will cause the body locking means 13 to flex away to allow the lever locking means 5 to move past it for further clockwise rotation of the lever 2. In a conventional manner this clockwise rotation of the lever 2 continues so that the engagement means 3 engages an upper side of the engagement formation 32 and upon further rotation pulls out the board module sufficiently to overcome the connecting forces of the connectors 29, 35. Then, the board module 20 is easily pulled out by hand in the extraction direction ED (see fig. 4A).

In brief, the above description clarifies that the invention eliminates the need for the conventional screw fastener to secure the board module 20 to the sub-rack 30 in the connected position and with the appropriate contact force or pressure. This is achieved by means of the lever that is pivotal between the inactive position where it is disengaged from the engagement formation and the position engaging the formation, to fully inject the board module into an electrically connected position in the chassis or sub-rack upon further pivoting, whereby the board module is continuously pressed into the fully connected and appropriately grounded position by the biasing force of the compressed spring. Thus, the invention effectively eliminates the time consuming and generally irritating task of attaching and removing said screw fasteners each time a board module is inserted or removed, respectively. This presents an important advantage, especially in laboratories where modules are frequently replaced. In addition thereto, the floating support of the pivot pin 9, as teached by the invention, is effective in taking up or allowing for tolerances in applications that meet the present standards according to which the board modules

20, or rather the board front 22, "bottom" against the outer support surface 38 of the sub-rack 30.

The invention has been described above with specific reference to illustrated embodiments thereof. However, it shall be understood that the invention is not restricted to these exemplifying embodiments. The basic principles of the invention may likewise be applied to other embodiments for use in similar or different applications. Therefore, modifications and variations of the invention that may be required in such applications or that may be otherwise desirable also fall within the scope of the invention. Examples of such modifications are illustrated in figs. 5A- C, 6 and 7.

In figs 5A-C is illustrated an injector/extractor 101 having a modified locking mechanism 105, 113 for the lever 102. In this case, the locking means 113 of the body 110 is slightly longer and is provided with a hook-like configuration at its upper end. At the end of the anti-clockwise rotation of the lever, the hook-like formation 113 is flexed slightly to the right in fig. 5 A and enters an aperture 105 in the lever top wall 108. Finally, in the fully injected position the hook- like formation 113 snaps back to grip the top surface of the wall 108 and thereby lock the lever 102 in position. Upon unlocking, the formation 113 is pushed back slightly to allow clockwise rotation of the lever 102. With specific reference to fig 5B, the pivot pin 9 is in this embodiment illustrated supported in a fixed position in bores 104 in the lever 102 side walls, only the bore 104 in side wall 106 being illustrated. Furthermore, the leaf spring 111 is illustrated having a slightly more simplified configuration. In summary, the modifications illustrated in figs. 5A-C provide the advantage of a somewhat simplified manufacture of the body 110 as well as of the lever 102. On the other hand such a fixed support of the pivot pin 9 in the lever 102 may make the engagement between the lever engagement means 3 and the sub-rack engagement means 32 more complicated, requiring also a modification (not illustrated) of the shape of the latter.

In fig. 6 is illustrated a further modified embodiment of the lever 202, where the pivot axis PA is formed by other means than a continuos pivot pin, such as by the illustrated stub shafts 209 formed integrally on the inner face of each lever side wall 206, 207 or alternatively being secured thereto. It will be realized that said stub shafts 209 are received in the openings in the side walls of the body 210 in the same manner as a continuos pivot pin. In this case, the biasing spring 211 will act directly upon the inner surface of the top wall 208 of the lever 202.

Fig. 7 illustrates an alternative embodiment of the body 310 of the injector/extractor 301. In this case, the body 310 is manufactured separate from the locking means 313 and they are separately secured to the board front 22 by means of screw fasteners 319. Fig. 8 illustrates an alternative solution for securing the pivot pin 409 in position. In accordance with said solution the middle section 409A of the pivot pin 409 is formed with a smaller diameter than the remainder of the pin. This middle section 409A cooperates with cutouts 411 A formed in side edges of the spring 411, thereby securing the axial position of the pin through the combined effect of the constant biasing force from the spring against the pin and the interlocking cooperation of the reduced section 409 A and the cutouts 411 A.

Finally, fig. 9 is a very schematic illustration of a sub-rack 30 with a partly inserted module 520 in an application using a slightly modified standard with regard to the locking and the positioning of the module in the connected position. Specifically, in the above described embodiments the board module has been injected to a fixed connected position determined by the contact between the board front and the outer support surface 38 of the sub-rack 30. In other words the board module has "bottomed" against the sub-rack at its outer side facing the board front and tolerances have been taken up within the connector parts 29, 35. With only minor modifications of the con- figuration, the basic features of the ύivention may be employed to effectively take up tolerances and to apply the required contact force also in applications where the board module would instead be allowed to "bottom" at the back-plane 39.

In accordance with the modified embodiment of the invention grounding springs 525, corre- sponding to those of figs. 4A-C, are employed that are compressible with a lower force than that required to compress the leaf spring 11 of the inventive injecting/extracting device 1. By allowing the connector parts 29, 35 to be fully engaged the injection of the board module 520 is stopped by the fact that said connector parts 29, 35 "bottom" against each other. This secures excellent contact between the connector parts.

In this case, tolerances in the sub-rack 30 and/or the board 521 are taken up at the contact point between the board front 522 and the outer sub-rack support surface 38, where the grounding spring 525 maintains appropriate grounding contact. This effect is obtained by dimensionally configuring the board module 520 so relative to the dimensions and positioning of the sub-rack 30 and of the sub-rack connector part 35 that when the connector parts 29, 35 are fully connected, blocking further injection of the module, a nominal play P remains between a bottom surface 522A of the board front 522 and the outer support surface 38 of the sub-rack 30. Expressed otherwise, the distance Dl between the bottom surface 522A of the board front 522 and an outer engagement end 29A of the board connector part 29 shall nominally be approximately 1 mm greater than the distance D2 between the outer support surface 38 of the sub-rack 30 and an inner engagement end 35A of the sub-rack connector part 35. It will be realized that this play P will effectively take up any reasonable tolerances so that the board module 520 does not "bottom" at the outer surfaces 522 A and 38. Likewise, the grounding spring 525 will be able to maintain good grounding contact during such movement of approximately 1mm, in the event that tolerances will have to be compensated for.

According to further, not specifically illustrated, modifications falling within the scope of the invention it may likewise be possible to support the pivot pin in a freely moveable manner, such as in circular or elliptical or otherwise formed openings that in all directions have dimensions exceeding the diameter of the pivot pin. Such a support may be provided both in the body and in the lever or in only one of them as long as the openings present a surface restricting upward movement of the lever or pivot pin beyond a point where the appropriate compression of the spring is obtained in the locked position of the lever. Likewise, other spring means than the illustrated leaf spring may be provided and the exact position of the spring may be varied.

Furthermore, the invention has been described herein with specific reference to preferred embodiments thereof that are specifically intended for use in telecommunications applications. It should be emphasized though, that the invention is in no way restricted to such applications. The basic principles of the invention may be applied to any system where electronic subassemblies are received in supporting chassis. Although the above description refers generally to an injector/extractor, it should be emphasized that the basic characterizing features of the invention refer to the injection sequence of a subassembly. Therefore, it falls within the scope of the invention to employ these basic features thereof in a device operating solely as an injector. This may be the case in applications where extraction of the subassemblies is carried out by means of a separate device.

It will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departure from the scope thereof, which is defined by the appended claims.

Claims

PATENT CLAIMS

1. An electronic subassembly (20; 520) for connection to a supporting chassis (30) and having a printed circuit board (21; 521) with outer and inner edges (26, 27) carrying a board front (22; 522) and electrical connectors (29) respectively and two side edges (28) for cooperation with board guides (34) during insertion into the chassis, said board front (22; 522) being provided with a subassembly injecting/extracting device (1; 101; 301) adjacent each side edge of the board, said injecting/extracting device comprising a lever (2; 102; 202) that is supported in a body (10; 110; 210; 310; 410) for pivoting about a pivot axis (PA) and that is provided with engagement means (3) for engaging a formation (32) on the chassis (30), a base (16) of said body being secured to the board front (22; 522), characterized in that:

- the pivot axis (PA) is displaceable for allowing restricted movement thereof relative to the body;

- the pivot axis is biased in a direction generally away from the base of the body; and - locking means (13; 113; 313, 5; 105) are provided for locking the lever (2; 102; 202) in a position (C) where it engages the formation (32) under simultaneous displacement of the pivot axis (PA) against the biasing force.

2. An electronic subassembly (20; 520) according to claim 1, characterized in that the pivot axis (PA) is displaceable in directions being generally normal to the board front (22; 522).

3. An electronic subassembly (20; 520) according to claim 1 or 2, characterized in that the lever (2; 102; 202) is supported on at least one pivot (9; 209) that is/are in turn floatingly supported in the body (10; 110; 210; 310; 410) and in that a biasing means (11; 111; 211; 411) is provided, acting directly or indirectly between the pivot/pivots and the base (16) of the body to urge the pivot/pivots and thereby the pivot axis (PA) in the direction for movement generally away from the base.

4. An electronic subassembly (20; 520) according to claim 3, characterized in that in an assembled condition of the subassembly injecting/extracting device (1; 101; 301) the biasing means (11; 111; 211; 411) applies a continuos biasing force to the pivot axis (PA) urging it towards an end position of its displacement in the direction generally away from the base (16).

5. An electronic subassembly (20; 520) according to any of claims 1-4, characterized in that the pivot axis (PA) is displaceable within the extent of elongate openings (12) in the body

(10; 110; 210; 310; 410).

6. An electronic subassembly (20; 520) according to any of claims 3-5, characterized in that the pivot axis (PA) is floatingly supported also in the lever (2).

7. An electronic subassembly (20; 520) according to claim 6, characterized in that the pivot axis (PA) is displaceable within the extent of elongate openings (4) in the lever (2), said elongate openings (4) in the lever (2) forming an angle ( ) with the elongate openings (12) of the body (10; 310) at least when the lever is in its locked position.

8. An electronic subassembly (20; 520) according to any of claims 1-7, characterized in that complementary locking means (13; 113; 313 and 5; 105, respectively) are provided and are secured to the board front (22; 522) and to the lever (2; 102), respectively.

9. An electronic subassembly (20; 520) according to any of claims 3-8, characterized in that the biasing means (11; 111; 211) is a leaf spring fixed to the body (10; 110; 210; 310).

10. An electronic subassembly (20; 520) according to any of claims 3-9, characterized in that the body (10; 110; 210) is an integral unit manufactured from steel plate and formed in one piece with a locking means (13; 113) and the biasing means (11; 111; 211).

11. An electronic subassembly (20; 520) according to any of claims 1-10, characterized in that the lever (2; 102; 202) is pivotal between an inactive position (A) where it is disengaged from the formation (32) on the chassis (30) and a position (B) engaging the formation, to fully inject the electronic subassembly into a connected position in the chassis upon further pivoting, whereby the electronic subassembly is continuously pressed into a fully connected position by the biasing force when the lever is in its locked position (C).

12. An injector/extractor (1; 101; 301) for an electronic subassembly (20; 520), comprising a lever (2; 102; 202) that is provided with engagement means (3) for engaging a formation (32) on a subassembly (20; 520) receiving chassis (30), and a body (10; 110; 210; 310; 410) having a base (16) for attachment to the subassembly, said lever (2; 102; 202) being supported in the body for pivoting about a pivot axis (PA), characterized in that:

- the pivot axis is displaceable for allowing restricted movement thereof relative to the body;

- the pivot axis is biased for movement generally away from the base of the body; and

- locking means (13; 113; 313, 5; 105) are provided for locking the lever in a fixed position engaging the formation (32), under simultaneous displacement of the pivot axis

(PA) against the biasing force.

13. An injector/extractor (1; 101; 301) according to claim 12, characterized in that the pivot axis (PA) is displaceable for restricted movement in directions being generally normal to the base (16).

14. An injector/extractor (1; 101; 301) according to claim 12 or 13, characterized in that the lever (2) is supported by at least one pivot (9; 209) that is in turn floatingly supported in the body (10; 110; 210; 310; 410) and in that a biasing means (11; 111; 211; 411) is provided, acting directly or indirectly between the pivot/pivots and the base (16) of the body to continuously urge the pivot/pivots and thereby the pivot axis (PA) in the direction generally away from the base.

15. An injector/extractor (1; 101; 301) according to claim 14, characterized in that in an assembled condition the biasing means (11; 111; 211; 411) applies a continuos biasing force to the pivot axis (PA) urging it towards an end position of its displacement in the direction generally away from the base (16).

16. An injector/extractor (1; 101; 301) according to any of claims 12-15, characterized in that the pivot axis (PA) is displaceable within the extent of elongate openings (12) in the body (10; 110; 210; 310; 410).

17. An injector/extractor (1; 301) according to any of claims 14-17, characterized in that the pivot axis (PA) is floatingly supported also in the lever (2).

18. An injector/extractor (1; 301) according to claim 17, characterized in that the pivot axis (PA) is displaceable within the extent of elongate openings (4) in the lever (2), said elongate openings (4) in the lever (2) forming an angle (α) with the elongate openings (12) of the body (10; 310) at least when the lever is in its locked position.

19. An injector/extractor (1; 101; 301) according to any of claims 14-18, characterized in that the biasing means (11; 111; 211) is a leaf spring fixed to the body (10; 110; 210; 310).

20. An injector/extractor (1; 101) according to any of claims 14-19, characterized in that the body (10; 110; 210) is an integral unit manufactured from steel plate and formed in one piece with a locking means (13) and the biasing means (11; 111; 211).

21. An injector/extractor (1) according to any of claims 12-20, characterized in that complementary locking means (13; 113, 5; 105) are provided on the body (10; 110) and on the lever (2; 102), respectively.

22. An injector/extractor (1; 101; 301) according to any of claims 12-21, characterized in that the lever (2; 102; 202) is pivotal between an inactive position (A) where it is disengaged from the formation (32) on the chassis (30) and a position (B) engaging the formation, to fully inject the electronic subassembly (20; 520) into a connected position in the chassis upon further pivoting, whereby the electronic subassembly is continuously pressed into a fully connected position by the biasing force when the lever is in its locked position (C).

23. A method of injecting an electronic subassembly (20; 520) into a supporting chassis (30) by means of an injecting device (1; 101; 301) comprising a lever (2; 102; 202) supported for pivoting in a body (10; 110; 210; 310; 410) fixed to the subassembly, comprising the steps of: - introducing the subassembly (20; 520) manually into the chassis (30); bringing engagement means (3) on the lever (2; 102; 202) into engagement with a complementary fixed abutment (32) on the chassis; pivoting the lever to inject the subassembly into a connected condition in the chassis; performing at least part of said pivoting against the force of a biasing means, compressing said biasing means during pivoting of the lever and thereby applying a contact force to the subassembly and the chassis; and locking the lever to the subassembly in the pivoted contact force applying position.