GB2035705A

GB2035705A - A module for accommodating circuit boards and other electrical equipment

Info

Publication number: GB2035705A
Application number: GB7938599A
Authority: GB
Original assignee: APW Electronics Ltd
Current assignee: APW Electronics Ltd
Priority date: 1978-11-08
Filing date: 1979-11-07
Publication date: 1980-06-18
Also published as: FR2441319A1; DE2848444A1; DE2848444C2

Abstract

A module for insertion into a rack for accommodating circuit boards has upper and lower rails 1 capable of being slid into the rack and having in their opposing faces two slots 8', 8'' for alternative reception of two circuit boards or of a circuit board 2 and a screening plate. The rails are joined by a front panel 11. <IMAGE>

Description

SPECIFICATION An improved module for accommodating circuit boards and other electrical equipment Racks for accommodating circuit boards are known which are constituted by a pair of metal end plates, pairs of upper and lower metal tie bars which extend between and connect the end plates and guide bars of plastics material which extend between the upper tie bars and between the lower tie bars in directions parallel to the end plates in opposed pairs, the guide bars having grooves in their opposing faces for accommodating the upper and lower edges of circuit boards slid endwise into the rack.

When a circuit board is required to carry heavy components, or delicate components which need protection, the practice is to mount the board in a module. This, in its simplest form, is a two rail module consisting of top and bottom metal rails joined to a metal front panel, the rails having in their opposed inner faces slots to accommodate the edges of a circuit board and on their outer faces ribs which can be slid into the slots of the guide bars in the rack.

Alternatively the module may be a four rail module carrying two circuit boards and including a pair of top rails and a pair of bottom rails which are joined by a back metal panel as well as a front panel.

In another version the module may be a so-called casette, which has no back panel but consists in effect of two two rail modules joined by top and bottom panels.

The object of the present invention is to provide an improved module which is more versatile than those hitherto available and which permits circuit boards to be introduced into the module at alternative locations and also permits a metal screening plate to be readily fitted. Such screening plates are sometimes required to prevent radiation of electrical or magnetic interference from the components mounted in the module or as protection for the components in the module.

The invention accordingly provides a module for insertion into a rack for accommodating circuit boards comprising an upper rail, an opposed lower rail, a front plate joining the rails together, each of the rails having in its inwardly facing surface an inboard and an outboard slot, a circuit board with its edges accommodated selectively in either the inboard slots or the outboard slots with an optional screening plate fitted into the outboard slots when the circuit board is accommodated in the inboard slots, said rails having throughgoing outboard and inboard holes which are tapped at their opposite ends, and mounting blocks carrying screws engaging the rear ends of said holes to attach the mounting blocks to the rails and other screws engaging holes in the circuit board to secure the board in the module.

One embodiment of module in accordance with the invention will now be described in detail, by way of example, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a vertical section looking from the front, Figure 2 is a plan view, Figure 3 is a perspective view showing certain parts at the rear of the module, Figure 4 is a rear view of the back panel of the module, Figure 5 shows a screening plate, and Figure 6 is a corresponding end view.

The module 10 illustrated is a four rail module having four rails 1 of extruded metal, each of which has an inboard slot 8" and an outboard slot 8'. As shown in Figure 1, the edges of circuit boards 2 can be slid into the inboard or the outboard slots of opposed top and bottom rails as desired. The circuit boards are attached at their rear ends to end connectors and, as will be seen from Figure 1, wider end connectors 9' can be used when a circuit board is accommodated in the inboard slots whereas narrower end connectors 9" must be used when the circuit board is accommodated in the outboard slots.

The end connectors are electrically connected to the circuit on the board 2 and have rearwardly projecting contact pins 19 (Figure 3) which fit into corresponding sockets in a rack when the module is inserted into the rack. When the circuit boards are in the inboard slots, screening plates 3' or 3" may be fitted into the outboard slots as shown in Figure 1.

As shown in Figure 2, the rails 1 are connected to a front panel 11 and to a back panel 5. As shown in Figure 3, each rail 1 has a rib 12 to enable the module to be slid into the guide bars of a rack of the kind described above, a flange 13 formed with a series of regularly spaced tapped holes 14 and a pair of throughgoing holes 18', 18" which are disposed adjacent the slots 8', 8" and are tapped at their outer ends.

Each rail 1 is attached to the circuit board 2 by a metal mounting block 4, having a projection (not shown) which fits into the tapped hole (18" in the case of Figure 3) adjacent the slot into which the board 2 is fitted. A fixing screw 15 is passed through a hole 15' in the block 4 into the other tapped hole, (18' in the case of Figure 3). The end connector 9' is attached to the board 2 and to the block 4 by a screw 16 which passes through holes in the end connector and the board and engages a tapped hole 17.

The block 4 shown in Figure 3 is appropriate for the case in which the board 2 is accommodated in the inboard slots 8" in the rails 1. When the board is accommodated in the outboard slots 8' an alternative form of block is used with the projection facing the hole 18' and the hole 15' facing the hole 18".

The front panel 11 is held in position by screws (not shown) inserted into the front ends of the holes 18' or 18" in the rails.

As shown in Figure 4, the back panel 5 has forwardly extending flanges 20, formed with holes through which screws are passed into the holes 14 (Figure 3) in the rails to secure the back panel to the rails. The back panel has perforations 21 and slots 22. When the module is used to accommodate in both pairs of rails circuit boards carrying end connectors the portion of the back panel seen at the left hand side of Figure 4 is broken off at the weakened portions 6 formed by the perforations 20 and the slots 21. When only one circuit board is required in the module the full width back panel can be used.

The screening plate 3' shown in Figures 5 and 6 has tongues 7 at one end which are engageable with the outboard slots 8' in the rails and at the other end notches 23 for the passage of fixing screws 24 (Figure 3) for attaching the plate to the mounting brackets 4.

Alternatively the module may be narrower and have two rails 1 only, in which case the back plate 5 is omitted.

Claims

1. A module for insertion into a rack for accommodating circuit boards comprising an upper rail, an opposed lower rail, a front plate joining the rails together, each of the rails having in its inwardly facing surface an inboard and an outboard slot, a circuit board with its edges accommodated selectively in either the inboard slots or the outboard slots with an optional screening plate fitted into the outboard slots when the circuit board is accommodated in the inboard slots, said rails having throughgoing outboard and inboard holes which are tapped at their opposite ends, and mounting blocks carrying screws engaging the rear ends of said holes to attach the mounting blocks to the rails and other screws engaging holes in the circuit board to secure the board in the module.

2. A module according to claim 1, in which said other screws also serve to attach an end connector to the circuit board.

3. A module according to claim 1 or claim 2, o having two opposed pairs of rails for respective accommodation of a pair of circuit boards and a back panel attached to the rails.

4. A module according to claim 3, in which the back panel has perforations defining weakened portions which can be broken to remove a side portion of the back panel.

5. A module according to claim 1, which includes a screening plate having tongues engaging the outboard grooves in the rails and notches for passage of screws attaching the screening plate to the mounting blocks.

6. A module according to claim 3, substantially as described herein with reference to the accompanying drawings.