GB2437292A

GB2437292A - Mounting bracket

Info

Publication number: GB2437292A
Application number: GB0607923A
Authority: GB
Inventors: Paul Mans
Original assignee: CP Electronics Ltd
Current assignee: CP Electronics Ltd
Priority date: 2006-04-21
Filing date: 2006-04-21
Publication date: 2007-10-24
Anticipated expiration: 2026-04-21
Also published as: GB0607923D0; GB2437292B

Abstract

A mounting bracket 5 for retaining a device 1 against a panel 25 has an abutment surface 21 for abutment against the panel. The bracket 5 has two first retaining projections 23a arranged to engage the device 1, and to retain the device at a first position in the direction normal to the plane of the abutment surface 21. The bracket has two second retaining projections 23b arranged to retain the device at a second position in the direction normal to the plane of the abutment surface 21. The second position is different to the first position. The first retaining projections 23a and the second retaining projections 23b are spaced in a direction parallel to the abutment surface, so that they can operate independently. The bracket can used to mount the device against rear surface of the panel or in a hole in the panel.

Description

MOUNTING BRACKET

Field of the Invention

This invention relates to a mounting bracket for retaining a device against a panel. In particular, this invention relates to a mounting bracket for retaining a sensor device, for example a microwave sensor device, against a panel.

Background to the Invention

Microwave sensor devices, such as the microwave present detectors available from C.P.

Electronics Limited of Wembley, United Kingdom, are used as occupancy sensors to control lighting, heating and ventilation systems in buildings and public areas, so that the systems only use power when required, i.e. when people are present. Such devices may be mounted in a wide variety of locations depending on the requirements of the particular installation. For example, a sensor device may be mounted to the reverse surface of the translucent fascia (diffuser) of a ceiling or wall light. Alternatively, the sensor device may be mounted within a luminaire (light fitting). Many luminaires have available space in which the sensor device can be located. However, in some cases, the sensor device must be located behind the casing of the luminaire in order not to adversely affect the aesthetics of the luminaire. Where the casing of the luminaire is metallic, the sensor device may be mounted with its sensing surface in a hole in the luminaire casing in order that the metal does not block the microwave radiation to and from the sensor device.

It is very desirable to provide a sensor device with a housing that is suited to installation in as many different configurations as possible, in order that a single product line can satisfy a wide variety of customers requirements. This invention provides, in particular embodiments, a mounting bracket that is particularly suited to retaining a microwave sensor device against a panel, but which can also be used to retain a microwave sensor device within a hole in such a panel.

Summary of the Invention

Accordingly, this invention provides a mounting bracket for retaining a device against a panel. The bracket comprises an abutment surface for abutment against the panel, in use.

The bracket further comprises at least one first retaining projection arranged to engage the device, in use, whereby to retain the device at a first position in the direction normal to the plane of the abutment surface, and at least one second retaining projection arranged to engage the device, in use, whereby to retain the device at a second position in the direction normal to the plane of the abutment surface. The second position is different to the first position and the first retaining projection(s) and the second retaining projection(s) are spaced in a direction parallel to the abutment surface.

Thus, according to the invention, the mounting bracket can retain the device in at least two positions relative to the abutment surface. For example, in the first position the device may butt up against the surface of the panel facing the bracket, and in the second position the device may project through a hole in the panel so that it is flush with the surface of the panel facing away from the bracket. This provides two mounting options using the same bracket and device.

By spacing the first retaining projection(s) and the second retaining projection(s) in a direction parallel to the abutment surface, the retaining projections can be formed independently, so that it is unnecessary to form single projections that can retain the device in two positions. This greatly simplifies the design of both the device and the bracket.

In general, the mounting bracket comprises a plurality of first retaining projections and a plurality of second retaining projections. The first retaining projections may be substantially equally spaced about the periphery of the device. The second retaining projections may be substantially equally spaced about the periphery of the device. In this way, the device is evenly supported by the retaining projections, in use. The first and second retaining projections may also be mutually spaced.

In the preferred embodiment, the bracket has two first retaining projections and two second retaining projections. The two first retaining projections are positioned on opposite sides of the device, in use, and the two second retaining projections are positioned on opposite sides of the device, in use.

The first and/or second retaining projections may be in the form of barbs. The barbs may have a device-engaging surface substantially parallel to the abutment surface and may decrease in width from the device-engaging surface in the direction away from the abutment surface. With this form of the projections, the device may be pushed between the barbs and will automatically click into position when the device-engaging surface of the appropriate barb engages the corresponding surface of the device.

The first and/or second retaining projections may be provided on respective resilient posts. For example, the resilient posts may be part of a plastics moulding forming the mounting bracket. The resilient posts assist in providing a positive engagement of the retaining projections with the device. The resilient posts may be substantially perpendicular to the abutment surface.

The resilient posts for the first retaining projections may have a different length to the resilient posts for the second retaining projections. In this way, the first position and the second position may be defined by the length of the resilient posts.

The first and/or second retaining projections may be arranged to engage the outer edge of the device furthest from the abutment surface, in use. In this way, it is unnecessary to provide specially-formed engagement surfaces for the retaining projections on the device.

Furthermore, if the device has a circular cross-section, the device can be rotated within the mounting bracket to achieve a desired orientation.

The invention extends to a mounting bracket as described, in combination with a device as described. The device may be an occupancy sensor, for example a microwave sensor or an infra red sensor. However, the invention is of application to any sensing device or, indeed, to any lighting device.

Furthermore, the invention extends to a method of mounting a device, as described in general herein. According to one possible mounting method, the abutment surface is glued to the panel. However, mounting with fixings such as screws or clips would also be possible.

Brief Description of the Drawings

An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view of a mounting bracket and microwave sensor according to an embodiment of the invention; Figure 2 is a reverse exploded perspective view of the microwave sensor of Figure 1; and Figure 3 is a slightly enlarged perspective view of the mounting bracket and microwave sensor of Figure 1 in the position of use.

Detailed Description of an Embodiment

Referring to Figure 1, a microwave sensor device 1 comprises a housing 2, a circuit board 3 and a lid 4. The sensor device I is mounted to a panel using a bracket 5, which will be described in detail below.

The circuit board 3 of the sensor device 1 includes a microwave sensor 6 and two control switches 7. Respective switch members 8 sit on the switches 7 and receive posts (not shown) within the housing 2 in order that they maintain alignment with the switches 7.

The tips 9 of the switch members 8 project through corresponding holes 10 in the housing 2, in order that the switches 7 can be operated from the outside of the sensor device 1 by pressing the tips 9 of the switch members 8.

The housing 2 is of a generally cylindrical form with a diameter of 40mm and a maximum height of 19mm. The sensing surface (uppermost in Figure 1) of the housing 2 is provided with a rebate with a width of 1mm and depth of 1mm about its periphery. This rebate allows the housing 2 to be flush mounted in 1mm sheet metal, which is typically used for light fittings. A sector of the sensing surface of the housing 2 is open and is fitted with a transparent plastics window (not shown) in order that the circuit board 3 can include a light level sensor 11.

The lid 4 is provided with a central square aperture for receiving electrical connections.

On either side of the square aperture, weakened portions 12 of the plastics material are provided for additional connection access, if required. The lid 4 includes two resilient lugs 13 which can be used to mount the device 1 to a corresponding pair of apertures (not shown), if required. The lid 4 connects to the housing 2 by means of seven projections 14 distributed about its periphery, which engage corresponding recesses 15 in the housing 2 (see Figure 2).

As shown in Figure 2, a fixing plate 16 can be connected to the housing 2 by barbed connectors 17 which engage corresponding slots 18 in the housing 2 and pass through cut-outs in the lid 4. The fixing plate 16 is provided with moulded holes 19 for screws and a central hole for electrical connections. The fixing plate 16 is also provided with weakened portions 20, which can be broken open to accommodate electrical connections. Holes in the fixing plate 16 accommodate the lugs 13 when the fixing plate is connected to the housing 2.

From the above it will be seen that the sensor device 1 can be mounted in position using the flexible lugs 13 or the fixing plate 16 and screws. However, as shown in Figure 1, the device 1 is also provided with a mounting bracket 5, as a further alternative fixing method. In this embodiment, the bracket 5 is formed as a single moulding of transparent plastics. The bracket 5 has an abutment surface in the form of a ring 21, which has a width of 5mm, giving an external diameter of 50mm. The internal diameter of the mounting bracket 5 closely matches the external diameter of the housing 2, so that the housing 2 is slidably received in the cylindrical portion 22 of the bracket 5. Integrally moulded with the ring 21 and the cylindrical portion 22 are four posts 23 provided with respective barbs 24 at their distal ends. The posts are provided as two pairs of opposed posts 23a, 23b, with each pair having a different length. The first posts 23a are shorter than the second posts 23b by 1mm, which corresponds to the depth of the rebate in the sensing surface of the sensor device 1, which in turn corresponds to the typical width of the metal sheet forming light fittings.

Figure 3 shows the device 1 mounted in a 38mm diameter hole in a 1mm sheet metal panel 25. The abutment surface 21 is bonded to the panel 25 with adhesive before the device 1 is inserted into the bracket 5. The device 1 is inserted between the barbs 24 of the post 23a, 23b (from above in Figure 3), which causes the posts to splay outwardly. In the case shown in Figure 3, the proud portion of the sensing surface of the device 1 passes through the hole in the panel 25, which means that lower surface of the barbs 24 of the shorter posts 23a engages the upper edge of the housing 2 and retains the device 1 in position against the panel 25. The sensing surface of the device 1 is flush with the outer surface of the panel 25. The barbs 24 of the longer posts 23b are clear of the upper edge of the housing 2, as shown in Figure 3, because they are 1mm longer than the shorter posts 23a.

Where the device is to be mounted to a panel that is transparent to microwave radiation, such as the diffuser of a light fitting, a hole is not required. The abutment surface 21 is again bonded to the panel 25 with adhesive before the device 1 is inserted into the bracket 5. The device 1 is inserted between the barbs 24 of the post 23a, 23b, which causes the posts to splay outwardly, as before. In this case, however, the sensing surface of the device 1 abuts the surface of the transparent panel at the point when the lower surface of the barbs 24 of the longer posts 23b engages the upper edge of the housing 2 to retain the device 1 in position up against the transparent panel. The shorter posts 23a remain splayed, but do not affect the retaining effect of the longer posts 23b.

It will be seen that the same mounting bracket 5 allows the sensor device 1 to be mounted securely in a hole in a metal sheet or behind a radiation-transparent fascia without any adaptation of the bracket.

In summary, a mounting bracket 5 for retaining a device 1 against a panel 25 has an abutment surface 21 for abutment against the panel. The bracket 5 has two first retaining projections 23a arranged to engage the device 1, and to retain the device at a first position in the direction normal to the plane of the abutment surface 21. The bracket has two second retaining projections 23b arranged to retain the device at a second position in the direction normal to the plane of the abutment surface 21. The second position is different to the first position. The first retaining projections 23a and the second retaining projections 23b are spaced in a direction parallel to the abutment surface, so that they can operate independently. The bracket can used to mount the device against rear surface of the panel or in a hole in the panel.

Although the invention has been described with first and second spaced retaining projections on the mounting bracket, similar effects may be achieved by providing at least one first engagement surface on the device arranged to engage a retaining projection on the bracket, in use, whereby to retain the device at a first position in the direction normal to the plane of the abutment surface, and at least one second engagement surface on the device arranged to engage the same retaining projection on the bracket, whereby to retain the device at a second position in the direction normal to the plane of the abutment surface. In this case, the second position is different to the first position and the first engagement surface(s) and the second engagement surface(s) are spaced in a direction parallel to the abutment surface. This alternative arrangement is not preferred because it complicates the form of the device by requiring spaced engagement surfaces and does not allow the device to have rotational symmetry about an axis perpendicular to the abutment surface.

Claims

Claims 1. A mounting bracket for retaining a device against a panel,

the bracket comprising: an abutment surface for abutment against the panel, in use; at least one first retaining projection arranged to engage the device, in use, whereby to retain the device at a first position in the direction normal to the plane of the abutment surface; and at least one second retaining projection arranged to engage the device, in use, whereby to retain the device at a second position in the direction normal to the plane of the abutment surface, the second position being different to the first position, wherein the first retaining projection(s) and the second retaining projection(s) are spaced in a direction parallel to the abutment surface.

2. A mounting bracket as claimed in claim 1 comprising a plurality of first retaining projections and a plurality of second retaining projections, wherein the first retaining projections are substantially equally spaced about the periphery of the device and wherein the second retaining projections are substantially equally spaced about the periphery of the device, in use.

3. A mounting bracket as claimed in claim 1 or 2, wherein the first andlor second retaining projections are in the form of barbs which have a device-engaging surface substantially parallel to the abutment surface and decrease in width from the device-engaging surface in the direction away from the abutment surface.

4. A mounting bracket as claimed in any preceding claim, wherein the first andlor second retaining projections are provided on respective resilient posts which are substantially perpendicular to the abutment surface.

5. A mounting bracket as claimed in claim 4, wherein the resilient posts for the first retaining projections have a different length to the resilient posts for the second retaining projections.

6. A mounting bracket as claimed in any preceding claim, wherein the first and/or second retaining projections are arranged to engage the outer edge of the device furthest from the abutment surface, in use.

7. A mounting bracket as hereinbefore described with reference to the Figures.

8. A mounting bracket as claimed in any preceding claim, in combination with a device.