GB2263199A - Circuit board front edge panel - Google Patents

Description

-I- 2263199 ENCLOSURE FOR CIRCUIT BOARD This invention relates to

cabinets, cases and other enclosures in which electrical and/or electronic apparatus is mounted on racks, trays or other supports housed in the enclosure. The invention is particularly concerned with enclosures of this kind in which circuit boards are accommodated in racks which are housed in the enclosure and which generally comprise a plurality of mutually spaced pairs of opposed guide rails into any pair of which opposed edges of a circuit board can be slid from the front of the rack. as the circuit board is slid fully home one or more than one edge connector mounted on the circuit board at or near its rear edge effecting electrical connection with a connector or connectors directly or indirectly carried by a backplane at the rear of the enclosure.

With a view to facilitating insertion of a circuit board into. and withdrawal of a circuit board from, a pair of opposed guide rails of the rack. it is the general practice to secure to the front edge of the circuit board, i.e. the trailing edge of the board as it is slid into the rails, a substantially rectangular flat plate, hereinafter referred to as the front plate, which serves as a handle. Neighbouring edges of the front plates of adjacent circuit board when slid fully home in their pairs of guide rails will lie close together so that when circuit boards are accommodated in all the 2. pairs of guide rails of the rack, the front plates of the boards together present a substantially flat surface at the front of the enclosure.

When a circuit board has been slid fully home in its pair of guide rails, it is also the general practice to detachably secure the board in position and this is Usually effected by means of fixing screws which pass through opposite ends of the front plate of the board and screw into tapped holes in opposed elongate members which extend transversely across the front of the enclosure adjacent the font ends of the pairs of guide rails. Each elongate member is customarily an extrudate of metal or metal alloy and, for reasons of ease of manufacture and cost, generally the tapped holes for reception of the fixing screws of the front plates of the circuit boards are formed in and mutually spaced along the length of a strip of metal or metal alloy which is separately formed with respect to each extrudate and which is removably housed in a pair of opposed grooves in said extrudate.

Where, as is usually the custom, the front plate of each circuit board is of metal or metal alloy, in some circumstances it is required for the front plates of adjacent circuit boards to be electrically interconnected after each board has been slid fully home, thereby to ensure that the front plate of each board will be effectively connected to earth. For this 1 3. purpose, it has been proposed to provide alongside one longer edge of the front plate of each circuit board at least one resilient electrical contact which will effect electrical connection with the front plate of the adjacent circuit board when one of said adjacent circuit boards is already accommodated in the enclosure and the other of said adjacent circuit boards is slid fully home in its pair of guide rails. Whilst this arrangement ensures that a satisfactory electrical connection is achieved between the front plates of adjacent circuit boards. as said other of the adjacent circuit boards is slid fully home there is a tendency for the resilient contact or contacts to urge the board transversely with respect to its direction of sliding motion to such an extent as to render difficult the effecting of electrical connection between the or each edge connector at the rear edge of the board and the connector or connectors of the backplane.

With a view to preventing or at least limiting the extent of transverse movement of the board caused by said resilient contact or contacts, it has been proposed to provide near each end of and protruding from the rear face of the front plate of each circuit board at least one substantially rigid pin, hereinafter referred to as a locating pin, which will engage in an associated hole in one of said opposed elongate members transversely extending across the front of the enclosure to locate 4. the front plate positively with respect to the elongate member as the circuit board is being slid fully home. Generally, the front plate of each circuit board has near each end of-and protruding from its rear face two transversely spaced locating pins which will engage in associated holes in one of said transversely extending elongate members. In arrangements currently available, each locating pin of the front plate of a circuit board is separately formed with respect to and is secured on the front plate; in one particular known arrangement.

locating pins at each end of the front plate of a circuit board are integral parts of a device, hereinafter referred to as a circuit board injector/ ejector device, which is secured to the front plate or to the circuit board to which the front plate is secured and which is designed to assist in insertion of the circuit board in, and extraction of the circuit board from, the enclosure.

It is an object of the present invention to provide, for use with a circuit board to be accommodated in a rack housed in an enclosure and to be electrically connected to a backplane at the rear thereof, an improved front plate which is simpler in construction and substantially less expensive than front plates hitherto proposed and used.

According to the invention, the improved front plate comprises a substantially rectangular flat panel S. of electrically conductive metal or metal alloy having near each end and protruding from the rear face of the panel at least one locating pin which is an integral part of the panel.

The or each locating pin near each end of the metal panel of the improved front plate may be integral with one boundary edge of a hole punched or otherwise formed in the panel but, preferably, each locating pin at least in part is a portion of the panel which is disposed between two slits extending lengthwise from the end edge of the panel and which has been so folded that it protrudes from the rear face of the panel and that a recess is formed in said end edge of the panel. Each locating pin may be of any desired length.

In a preferred embodiment, the improved front plate comprises two substantially flat panels secured face-to-face, the rear or inner panel being said panel of electrically conductive metal or metal alloy having near each of its ends at least one locating pin which is an integral part of the panel and the front or outer panel being of metal or metal alloy and having an overall coating of electrically insulating material or being of electrically insulating material. The two panels of the improved front plate may be secured faceto-face by any convenient means but, preferably, the panels are permanently or detachably secured together at or near each of their ends by at least one rivet or bolt having a throughbore for reception of a fixing screw for 6. screwing into a tapped hole in, and thereby securing the front plate to, one of two opposed elongate members which extend transversely across the front of a rack. The throughbore of the or each rivet or bolt securing together the panels of the improved front plate may be internally screw threaded so that the associated fixing screw can be retained therein. The front or outer panel preferably overlies the holes or recesses in the rear or inner panel from the boundary edges of which the integral locating pins extend rearwardly and will prevent dirt or other foeign matter from entering an enclosure through these holes or recesses. Moreover, the outer face of the front or outer panel may be readily provided with any appropriate legend that may be required and, where the front or outer panel is detachably secured to a rear or inner panel, may be readily replaced.

The panel of electrically conductive metal or metal alloy preferably has extending along at least a major part of the length of one or each of its side edges a flange which is integral with and extends rearwardly from the panel and which may have secured thereto at least one resilient electrical contact for effecting electrical connection with a rearwardly extending flange of the metal panel of the front plate of an adjacent circuit board.

7.

Preferably, each hole or recess in the metal panel from a boundary edge of which an integral locating pin extends rearwardly underlies a circuit board injector/ ejector device which is secured to the front plate or the circuit board to which the front plate is secured and which thereby prevents or substantially reduces the risk of dirt or other foreign matter entering an enclosure through said hole or recess.

The invention also includes an improved circuit board for accommodating in a rack housed in an enclosure and for effecting electrical connection to a backplane at the rear of the enclosure, which circuit board comprises at least one edge connector mounted on the circuit board at or near its rear edge for effecting a multiplicity of pin and socket electrical connections with a connector directly or indirectly carried by a backplane at the rear of the enclosure and, secured to the front edge of the circuit board, an improved front plate substantially as hereinbefore described.

The invention is further illustrated by a description, by way of example, of a preferred front plate for securing to the front edge of a circuit board with reference to the accompanying drawings, in which:-

Figures 1, 2 and 3, respectively, are front, side and end views of the preferred front plate; 8.

Figure 4 is a perspective view of a rack for accommodating circuit boards and for housing in an enclosure; Figure 5 is a perspective view of a circuit board for accommodating in the rack shown in Figure 4, with a preferred front plate secured thereto; Figure 6 is a fragmental view from above of the circuit board and front plate shown in Figure 5, and Figures 7 to 9 are fragmental side views, partly in section and partly in elevation, of one end of the front plate of the circuit board shown in Figures 5 and 6 with a circuit board injector/ejector device mounted thereon, Figure 7 showing use of the device to provide the force necessary to effect a multiplicity of pin and socket connections at the rear of the circuit board, Figure 8 showing locking of the device to prevent withdrawal of the circuit board and Figure 9 showing use of the device to provide the force necessary to disconnect the multiplicity of pin and socket connections at the rear of the circuit board.

Referring to Figures 1 to 3, the preferred front plate 14 is of a composite form and comprises two flat rectangular panels riveted face-toface, the rear or inner panel 15 being of electrically conductive metal or metal alloy and the front or outer panel 16 being of electrically insulating material. The inner panel 15 of the composite front plate 14 has extending along a major 9. part of the length of each of its side edges a flange 17 which is integral with and extends rearwardly from the panel. Electrically connected to the outer face of one of the flanges 17 is a resilient electrical contact 18 which will effect electrical connection with a flange of the inner panel 15 of the composite front plate 14 of an adjacent circuit board when one of the adjacent circuit boards is already accommodated in a rack and the other of the adjacent circuit boards is slid fully home into its pair of guide rails. The composite front plate 14 has protruding rearwardly from each of its upper and lower ends a pair of transversely spaced locating pins 19 which are integral parts of the rear or inner panel 15. Each locating pin 19 is a portion of the rear or inner panel 15 which is disposed between two slits 20 extending lengthwise from the adjacent end edge of the panel and which has been so folded that it protrudes from the rear face of the panel.

The rack 1 shown in Figure 4 comprises a plurality of mutually spaced pairs of opposed horizontal guide rails 2 into any pair of which opposed upper and lower edges of a circuit board can be slid from the front of the rack. In the rear of an enclosure in which the rack will be housed would be disposed a plurality of connectors (not shown) directly or indirectly carried by a backplane, each of which connectors has in its front face a multiplicity of sockets. Extending transversely 10. across the front of the rack 1 along each of its upper and lower edges is an extrudate 5 of metal alloy having throughout its length a pair of opposed grooves 6 (Figures 7 to 9) in which an elongate metal member 7, separately formed with respect to the extrudate, is removably housed. Each elongate metal member 7 is of Tshaped transverse cross- section with opposite ends of the head of the T removably housed in the opposed grooves 6 in the associated extrudate 5. The limb of each T- shaped elongate member 7 has throughout the length of the member a piurality of mutually spaced castellations 21 and the head of each T- shaped elongate member has throughout the length of the member a plurality of mutually spaced holes 22, each in axial alignment with a gap between two adjacent castellations in the limb. The gap between any two adjacent castellations 21 in the limb of the T-shaped elongate member and the axially aligned hole 22 extending throughout the thickness of the head of the T-shaped elongate member together constitute one of a multiplicity of guides 10 mutually spaced along the length of the elongate member, each guide thereby being capable of accommodating a locating pin 19 of a front plate 14 of any length within a limited range of lengths of locating pin. Each extrudate 5 also has throughout its length a flange 8 which extends forwardly from the 11. front face of the rack 1 and in which a channel 9 extends throughout the length of the flange, the purpose of which will be explained hereinafter.

Referring to Figures 5 and 6, a circuit board 11 for accommodating in the rack 1 has mounted on the board at or near its rear edge an edge connector 12 from which protrudes a multiplicity of pins for effecting pin and socket connections with the multiplicity of sockets of a connector at the rear of the aforesaid enclosure. Secured to the front edge of the circuit board 11 by brackets 13 is a rectangular front plate 14 as illustrated in Figures 1 to 3. When the circuit board 11 is slid into a pair of opposed guide rails 2 adjacent a circuit board already accommodated in the rack 1, the pair of transversely spaced locating pins 19 protruding rearwardly from the upper and lower ends of the composite front plate 14 of the board are adapted to engage between adjacent castellations 21 constituting parts of the guides 10 of the elongate metal members 7 to locate the composite front plate positively with respect to the extrudates 5 as the circuit board is slid fully home in the guide rails. Such positive location of the composite front plate 14 of the circuit board 11 prevents the resilient contact 18 of the front plate, when effecting electrical connection with a flange of the inner panel 15 of the composite front plate 14 of said adjacent circuit board, from urging the circuit 12. board 11 transversely to its direction of sliding motion to such an extent as to render difficult the effecting of the multiplicity of pin and socket connections at the rear of the enclosure in which the rack is housed.

At or near each end of the composite front plate 14 is a preferred circuit board injector/ejector device 31 comprising a body 32 which is fixedly secured to the composite front plate and a lever 33 which is pivotally mounted on the body about a horizontal pivotal axis 34. The lever 33 has a tongue 35 which, when the lever is pivoted in a direction towards the front face of the composite front plate 14, will protrude beyond the body 32 so that a rounded surface 36 on the tongue will bear against an inclined side face 37 of the channel 9 in the flange 8 of the associated extrudate 5, which inclined side face constitutes the "push- in" surface of the extrudate. The lever 33 also has a fixing screw 38 which is so screw threaded in a tapped hole 39 in the lever that the fixing screw cannot be readily removed therefrom and which is adapted to screw into a tapped hole 40 in the body 32. Projecting from the outer end of the lever 33 is a finger 41 having a rounded end 42 which, when the lever is pivoted in a direction away from the front face of the composite front plate 14, will bear against the front end face 43 of the flange 8 of the associated extrudate 5, which front end face constitutes the "push- out" surface of the extrudate. A 13. leaf spring 44 accommodated in the device urges the pivotally mounted lever 33 in a direction away from the front face of the composite front plate 14.

Referring specifically to Figures 7 to 9, when the circuit board 11 is to be accommodated in the rack 1 housed in an enclosure, the leading ends of the upper and lower edges of the circuit board 11 are introduced into a pair of opposed guide rails 2 and the circuit board is slid between the guide rails until the locating pins 19 protruding rearwardly from the composite front plate 14 initially engage in guides 10 of the T-shaped elongate members 7. The levers 33 at the ends of the composite front plate 14 are then pivoted in a direction towards the front face of the composite front plate against the action of the leaf springs 44 so that the rounded surfaces 36 of the tongues 35 protruding beyond the bodies 32 bear against and co-operate with the "push-in" surfaces constituted by the inclined side faces 37 of the channels 9 in the flanges 8 of the extrudates 5 to assist in providing the force necessary to effect the multiplicity of pin and socket connections between the edge connector 12 at the rear of the circuit board 11 and a connector at the rear of an enclosure in which the rack 1 is housed. When the circuit board 11 has been slid fully home and the multiplicity of pin and socket connections has been effected, the rounded surfaces 36 of the tongues 35 bearing against the 14. inclined side faces 37 of the channels 9 prevent withdrawal of the circuit board 11 from the enclosure. The fixing screws 38 are then screwed into the tapped holes 40 in the bodies 32 to prevent pivotal movement of the levers 33.

When the circuit board 11 is to be withdrawn from the rack 1, the fixing screws 38 are unscrewed from the tapped holes 40 in the bodies 32 and the levers 33 are pivoted in a direction away from the front face of the composite front plate 14 so that the rounded ends 42 of 1 the fingers 41 bear against and co-operate with the "push-out" surfaces constituted by the front end faces 43 of the flanges 8 of the extrudates 5 to assist in providing the force necessary to effect disconnection of the multiplicity of pin and socket connections at the rear of the circuit board and, since the tongues 35 are no longer engaged in the channels 9, the circuit board can then be readily slid outwardly from the rack 1.

1 i 15.

Claims (12)

1. A front plate for securing to the front edge of a circuit board to be accommodated in a rack housed in an enclosure and to be electrically connected to a backplane at the rear thereof, which front plate comprises a substantially rectangular flat panel of electrically conductive metal or metal alloy having near each end and protruding from the rear face of the panel at least one locating pin which is an integral part of the panel. 1

2. A front plate as claimed in Claim 1, wherein the or each locating pin near each end of the metal panel is integral with one boundary edge of a hole punched or otherwise formed in the panel.

3. A front plate as claimed in Claim 1, wherein the or each locating pin near each end of the metal panel at least in part is a portion of the panel which is disposed between two slits extending lengthwise from the end edge of the panel and which has been so folded that it protrudes from the rear face of the panel and that a recess is formed in said end edge of the panel.

4. A front plate as claimed in Claim 2 or 3, wherein the front plate comprises two substantially flat panels secured face-to-face, the rear or inner panel being said panel of electrically conductive metal or metal alloy having near each end and protruding from the rear face of the panel at least one locating pin which is an 16. integral part of the panel and the front or outer panel being of metal or metal alloy and having an overall coating of electrically insulating material or being of electrically insulating material.

5. A front plate as claimed in Claim 4, wherein the front or outer panel overlies the holes or recesses in the rear or inner panel from the boundary edges of which the integral locating pins extend rearwardly.

6. A front plate as claimed in Claim 4 or 5, wherein the panels are permanently or detachably secured together at or near each of their ends by at least one rivet or bolt having a throughbore for reception of a fixing screw for screwing into a tapped hole in, and thereby securing the front plate to, one of two opposed elongate members which extend transversely across the front of a rack.

7. A front plate as claimed in Claim 6, wherein the throughbore of the or each rivet or bolt securing together the panels is internally screw threaded so that the associated fixing screw can be retained therein.

8. A front plate as claimed in any one of Claims 2 to 7, wherein each hole or recess in the panel from a boundary edge of which an integral locating pin extends rearwardly underlies a circuit board injector/ejector device which is secured to the front plate or to the circuit board to which the front plate is secured.

17.

9. A front plate as claimed in any one of the preceding Claims, wherein the panel of electrically conductive metal or metal alloy has extending along at least a major part of the length of one or each of its side edges a flange which is integral with and extends rearwardly from the panel and which has secured thereto at least one resilient electrical contact for effecting electrical connection with a rearwardly extending flange of the metal panel of the front plate of an adjacent circuit board. 1

10. A circuit board for accommodating in a rack housed in an enclosure and for effecting electrical connection to a backplane at the rear of the enclosure, which circuit board comprises at least one edge connector mounted on the circuit board at or near its rear edge for effecting a multiplicity of pin and socket electrical connections with a connector directly or indirectly carried by a backplane at the rear of the enclosure and a substantially rectangular front plate secured to the front edge of the circuit board, wherein the front plate comprises a substantially rectangular flat panel of electrically conductive metal or metal alloy having near each end and protruding from the rear face of the panel at least one locating pin which is an integral part of the panel.

11. A front plate for securing to the front edge of a circuit board to be accommodated in a rack housed in an 18. enclosure and to be electrically connected to a backplane at the rear thereof substantially as hereinbefore described with reference to and as shown in Figures 1 to 3 of the accompanying drawings.

12. A circuit board for accommodating in a rack housed in an enclosure and for effecting electrical connection to a backplane at the rear of the enclosure substantially as hereinbefore described with reference to and as shown in Figures 5 to 9 of the accompanying drawings. 1