GB2339972A

GB2339972A - Housing for an electrical device.

Info

Publication number: GB2339972A
Application number: GB9910707A
Authority: GB
Inventors: Nicholas Sims
Original assignee: GARDINER TECHNOLOGY Ltd
Current assignee: GARDINER TECHNOLOGY Ltd
Priority date: 1998-05-08
Filing date: 1999-05-07
Publication date: 2000-02-09
Also published as: GB9809949D0; GB9910707D0

Description

2339972 Housing for an electrical or electronic device The present

invention relates to a housing for an electrical or electronic device. The invention has particular, but not exclusive, application to a housing for a component of an alarm system.- Devices such as detectors for use in an alarm system are normally contained within a housing. The housing includes a base, which is generally rectangular in outline, and which has means by which it can be secured to a support, such as a window frame, and means to retain the device itself in place on the base. The housing must also provide a cover removably mounted on the base to protect the device, a fastener for the cover, and one or more openings through which electrical wires may pass to make electrical connections to the device. There is also often a need to provide a viewing aperture through which an indicating light mounted on the device can be visible.

There is a very strong preference that the viewing aperture and the fastener are provided on a common surface of the cover. If this were not the case, many problems would likely be encountered in trying to find a suitable mounting location for the device. A consequence of this requirement is that the cover can be fitted into place on the housing in just one orientation. This is a source of difficulty for an installer who must ensure not only that the base is correctly positioned on the support, but also that it is disposed in the correct orientation. This has been found to cause much practical inconvenience and much wasted time and effort.

2.

An aim of the invention is to provide a housing for an electrical or electronic device which is easier to install than is the case with known housings.

According to a first aspect of the invention there is provided a housing for an electrical or an electronic device comprising a base which has means by which it can be secured to a support and means to retain the device on the base, and a cover removably mounted on the base to enclose the device, wherein the cover can be secured to the base in one of a plurality of orientations, and a plurality of viewing apertures, a respective viewing aperture being disposed adjacent a light source of the device when the cover is mounted in a corresponding one of the said orientations.

The device may be retained on the base in one of a plurality of orientations.

Preferably, the cover has a central securing aperture through which a fastener is extendable to secure the cover to the base. Furthermore, the viewing apertures should be spaced symmetrically from the securing aperture.

Since the securing aperture is central of the cover, its position with respect to the base does not change irrespective of the orientation with which the cover is mounted on the base. By providing a plurality of viewing apertures, it is possible to ensure that the light source is visible irrespective of the orientation in which the cover is mounted.

3 In most casesi the number of viewing apertures will be equal to the number of orientations. Most typically, the base is generally rectangular in outline, with the result that the cover can be mounted in -either one of two alternative orientations, and so it will be provided with two viewing apertures.

Preferably, a transparent or translucent aperture cover is provided to cover one or more of the viewing apertures. Furthermore, in order that the cover is not seen to have an open, unused aperture when mounted for use, the aperture cover is preferably provided to cover all of the viewing aperture. Thus, the unused apertures will not be noticed by a user. This arrangement can provide a smooth, finished appearance to the cover.

In another preferred embodiment of the present invention, one or more transparent or translucent aperture covers are provided which each cover a respective viewing aperture. Those viewing apertures which are covered are therefore covered individually, in groups, or both.

openings in the housing for electrical wires may be provided in the form of break-outs. That is to say, lines of weakness are formed in the material of the housing and allow a portion of it to be broken away to reveal an aperture through it. Typically, several break- outs are provided, to allow an installer to choose to use those which are most convenient for an installation task.

In order to protect the electrical wires, and to isolate the device from hostile environmental effects, it 4 is normal to provide a grommet in any aperture through which a wire passes. It has been found that moisture can seep through the grommet to enter the housing in some conditions. In order to reduce such seepage, another aspect of the 'invention proposes that a grommet be provided in an aperture of a housing, the grommet having a passage through which a wire can pass, which passage includes at least a portion which, in use, is arrangable to slope downwardly to the exterior of the housing. In a preferred embodiment, substantially all of the passage is arrangable to slope downwardly to the exterior. Such grommets can be used with a housing according to the first aspect of the invention.

An embodiment of the invention will now be described in detail, by way of example, and with reference to the accompanying drawings, in which:

Figures 1 and 2 are part-sectional views of a housing embodying the invention, respectively, in plan and of one side; Figure 3 is a plan view of a base of a housing embodying the invention showing an electronic device mounted on it; 25 Figure 4 is a sectional view of the base illustrated in Figure 3; Figure 5 is a plan view of a cover of a housing embodying the invention; Figure 6 is a sectional view of the cover illustrated in Figure 3; Figure 7 is a sectional view of a lens of the cover illustrated in Figures 5 and 6; Figure 8 is a view from below of the lens of Figure 7; and Figures 9 and 10 respectively are sectional and side views of a grommet suitable for use within the cover of Figure 5.

A housing 10 embodying the invention is illustrated in the drawings. The housing 10 is intended to contain an electronic vibration sensing device which is constructed on a single circuit board 12. A typical application of the device 12 is to detect vibration which might occur during forced entry into a building through a locked door or window. The device 12 includes a light-emitting diode 14 which is switched on by the device in the event that it detects vibration and a terminal block 16 to which electrical connection to the device is made.

The housing 10 comprises a base 20 and a cover 22, each made as a respective one-piece plastic moulding.

The base 20 includes a baseplate 24 which is shaped as a slightly rounded rectangle, such that it has a major axis A and a minor axis B. The baseplate 24 lies, in use, in contact with a supporting surface 32, such as a member of a window or door frame. Apertures 26 are provided in the baseplate 24 through which screws 28 or other fasteners can be passed in order to secure the baseplate 24 onto the surface 32. These apertures 26 may be countersunk, as is conventional, to accommodate a screw head.

A pair of side walls 30 project from the baseplate 24. The side walls 30 extend parallel to and spaced symmetrically from the major axis A. The circuit board 12 6 is located between the walls 30 and is supported spaced away from the baseplate 24 on four support formations 34. Each support formation 34 includes a clip portion which serves to retain the circuit board 12 in place on it. Centrally of the baseplate, there projects a spigot 40. The spigot 40, in this embodiment, projects through a central hole 44 in the circuit board 12. The spigot has an open-ended axial bore 42 which is tapped with a screw 10 thread. The LED 14 is positioned on the board 12 close to the hole 44. The cover 22 is formed as a one-piece moulding of plastic. The cover 22 comprises an outer wall 46 of shape 15 similar to that of the profile of the base 20. A skirt 48 projects from the outer wall 46 around its periphery, to form an enclosure with one open face. The cover 22 is shaped and dimensioned such that the skirt 48 can surround the base 20 with minimal clearance so as to form 20 an enclosed housing. The cover 22 is rotationally symmetrical about a central axis such that it can be placed on the base 20 in either one of two orientations, being rotationally spaced from one another by 1801. 25 Centrally of the outer wall 46 is a recess 50 which in this embodiment is elliptical. Within the recess 50 there is a central aperture 52 through the outer wall 46 and a pair of symmetrically disposed viewing apertures 54. The viewing apertures 54 are positioned such that a 30 respective one of them is positioned over the LED 14 in a respective one of the orientations of the cover 22. A locating spigot 56 extends from the outer wall 7 into the cover 22. The locating spigot 56 has a central bore 58 into which an end part of the spigot 40 of the base 10 can be received. This arrangement provides secure location of the cover 22 on the base 20. A screw fastener (not shown) can be inserted through the central aperture 52 into the bore 42 of the spigot 40 to securely fasten the cover 22 in place.

A lens 60 of moulded plastic is located on the cover 22. The lens 60 has an elliptical diaphragm portion 64 which is a close fit within the recess 50, to provide a smooth outer profile of the outer wall 46. The lens 60 includes two pairs of projections 62 each of which pairs extends through a respective viewing aperture 54. Each projection 62 has a curved end surface. One of the pairs of projections 62 extends towards the LED 14 in the assembled article. Light emitted by the LED is thereby collected and conducted to the diaphragm 64 which it can be seen by an observer.

Break-out regions 66 are formed in the skirt 48 in a conventional manner. In those break-out regions which are opened for use, a grommet 68 is inserted to protect and seal against electrical wires (not shown) passing into the housing. The grommet 68 has external formations which enable it to be located in place within the breakout region 66. Internally, the grommet 68 has a bore 70through which a wire can pass. The bore 70 is sloped outwardly of the housing towards the supporting surface 32, and tapers outwardly. This arrangement directs the wire towards the supporting surface 32, so contributing to a neat installation. Furthermore, it is common for the housing to be mounted on an upwardly- directed supporting 8 surface. In this arrangement, the slope of the bore 70 discourages ingress of water into the housing.

9

Claims

1. A housing apparatus for an electronic or electrical device including a base which has means by which the base is securable to a support and means to retain the device on the base, a cover removably mounted on the base to enclose the device, wherein the cover is securable to the base in one of a plurality of orientations, and a plurality of viewing apertures, a respective viewing aperture being disposed adjacent to a light source of the device when the cover is mounted in a corresponding one of the said orientations.

2. The apparatus of claim 1 including means whereby the device is retainable on the base in one of a plurality of orientations.

3. The apparatus of either of the above claims in which the cover has a central securing aperture through which a fastener is extendable to secure the cover to the base.

4. The apparatus of any of the preceding claims in which the viewing apertures are spaced symmetrically from the securing aperture.

5. The apparatus according to any of the above claims including one or more transparent or translucent aperture covers which each cover a viewing aperture.

6. The apparatus of any of claims 1-4 including one or more transparent or translucent covers which together or individually cover all the viewing apertures.

7. The apparatus of any of the above claims in which the base is substantially rectangular.

8. The apparatus of any of the above claims including 5 two viewing apertures.

9. The apparatus of any of the above claims wherein the cover has means for attachment to the base in one of two possible orientations.

10. The apparatus of any of the above claims including one or more apertures in the housing provided to allow electrical wires to pass into the housing

11. The apparatus of any one of claims 1-9 including one or more break- out sections in the housing by which one or more apertures are providable.

12. A housing apparatus for an electronic or electrical device including a grommet provided in an aperture of the housing, the grommet having a passage through which the wire can pass, which passage includes at least a portion which, in use, is arrangable to slope downwardly to the exterior of the housing.

13. The apparatus of claim 12 wherein substantially all of the passage is arrangable to slope downwardly to the exterior of the housing.

14. In combination, the apparatus of either claims 12 or 13 with any of claims 1-11.

15. A housing apparatus substantially as any one 11 embodiment herein described, with reference to, and as illustrated in, any of the accompanying drawings.