Luminaire

Abstract

The luminaire comprises an over-centre type clip 13 having a first section 15 pivotally secured to a housing 11 or cover 12 of the luminaire and a second section 16 pivotally secured to the first and

Description

This invention relates to a luminaire and in particular, though not exclusively, to a luminaire of the type comprising a housing and a cover which is removable to facilitate access to a light source within the housing. The provision of a removable cover, such a diffuser, is a standard feature of batten type lights so as to enable replacement of a non-functioning light source within the housing and also for ease of attachment of the housing to a support such as a wall or ceiling surface. Typically the diffuser is removably secured to the housing by means of bistable over-centre by clips. Although these clips are readily operable to facilitate removal of the diffuser, they can present difficulty when securing a diffuser to a housing and especially when the housing is secured to an overhead support such as a ceiling. One attempt to address that difficulty is the subject of GB 2612649. That relates to provision of clips of a bi-stable, over-centre type in which one part of a clip can be moved to a position disposed sideways of the housing to allow the diffuser to be moved into alignment with the housing. In order to secure the clips temporarily in that sideways position two parts of each clip are interference fit with one another thereby to provide a frictional force to hold the clip in a sideways position. A disadvantage of that attempt to address the difficulty encountered in use of said clips is that it is necessary to move each clip individually to a sideways position before presenting the diffuser to the housing. There is the need also to ensure that when presenting the diffuser to the housing none of the clips are inadvertently displaced to a position at which they impede movement of the diffuser towards the housing. The present invention seeks to provide a luminaire which more conveniently and effectively facilitates ensuring that the clips do not adversely interfere with presenting the diffuser into engagement with the housing. In accordance with one aspect of the present invention there is provided a luminaire comprising a removable cover which is securable to a light source housing by means of at least one over-centre type clip, said clip comprising a first section pivotally secured to the housing or diffuser and a second section pivotally secured to the first section and provided with a distal end formation adapted for engaging with a receiving section on the other of the housing and diffuser, the clip further comprising a spring which, prior to use of the clip to secure the diffuser to the housing, inherently acts to resiliently bias the two sections of the clip to reside in a predetermined orientation relative to one another, the second section being pivotable relative to the first section by applying a force to counteract the biasing effect of the spring for securing together the diffuser and housing. The spring may, for example, be a leaf spring or a torsion spring. A torsion spring may comprise at least one coil of one or more turns of spring steel. The torsion spring may be positioned with the major axis of the coil coincident with the axis about which the two sections of the clip are pivotable relative to one another. The spring may comprise two coils that are spaced apart along the axis about which the two clip sections are pivotable relative to one anther. The torsion spring may comprise two end regions which each extend outwards from the coiled region to bear respectively against the surfaces of the first and second clip sections. One or each of the end regions may comprise a distal end portion that extends parallel with the axis about which the two clip sections are pivotable relative to one another. If the spring comprises two coils, the distal end portion of an end region of one coil may be integral with the distal end portion of an end region of the other coil. The distal end formation of the second section may be a lip shaped formation. Optionally the clip may comprise stop means to restrict the angle of movement of the clip sections relative to one another under the action of spring force. The invention envisages that a spring may be in a substantially unstressed rest position when the second section of the clip is supported by the spring in a position extending sideways and outwards from the position at which the diffuser is moved into alignment with a confronting surface of the housing. Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:- Figure 1 is a perspective view of a batten type luminaire; Figure 2 shows in detail an end region of the luminaire of Figure 1; Figure 3 is an end view of the luminaire of Figure 1; Figure 4 is a perspective view of a clip of the luminaire of Figure 1; Figure 5 is a side view of the clip of Figure 4; Figure 6A is a plan view of the clip of Figure 4; Figure 6B is a view of the underside of the clip of Figure 4; Figure 7 is a section on the line A-A of Figure 6; Figure 8 is a perspective view of the torsion spring of the clip of Figure 4; Figure 9 is a perspective view of the spring of a luminaire in accordance with a second embodiment of the invention; Figure 10 is a perspective view of a clip incorporating the spring of Figure 9, and Figure 11 is a view of the underside of the clip of Figure 10. A luminaire 10 of the batten type comprises a housing 11 for housing a light source and a diffuser 12 which is removably secured to the housing by means of a plurality of clips 13. The clips 13 function in an over-centre manner and each comprise a first section 15 pivotally secured to the housing and a second, distal section 16 that is pivotally secured to the first section by means of a pivot pin19. In this embodiment the clip sections 15, 16 are formed from moulded plastics material. The first section of each clip comprises a pair of shanks 17 that click fit in known manner in a pair of clip supports 18 of the housing. The distal end of the second clip section 16 comprises a lip formation 20 which, in use of the clip to retain a diffuser in position relative to a housing, engages with an overhang surface 21 of the diffuser as best seen in Figure 3. The clip additionally comprises a torsion spring 24 as shown in Figure 8 and in situ in the clip as shown in Figure 4. The spring 24 comprises a pair of coils 25 of spring steel wire which, in situ, extend around shanks 26 at the ends of the pin 19 of the pivot formation located between the first and second clip sections. The spring comprises a connecting section 27 which extends between the two coils 25 spaced from but parallel with the length of the pivot pin 19. The other end region 28 of each coil terminates at a position 29 spaced from the pivot axis defined by the pivot pin end shanks 26. Accordingly each coil 25 comprises end sections 33, 39 that extend outwardly from the coil and distal sections 27, 34 that extend parallel with the major axes of the two coils. When the spring is in situ in the clip, the interconnecting section 27 bears against the underside surface 30 of the second clip section and the spring end sections 34 bear against the underside surface 31 of the first clip section as shown in Figure 7. In an unstressed condition of the spring prior to deployment of the spring to secure the diffuser to the housing the spring lightly supports the second clip section 16 to extend outwards in a sideways direction from the housing as shown in Figure 2 and 3. In this condition the underside surface 31 of the first clip section 15 is supported by a shoulder region of the housing whereby the first clip section is not free to rotate clockwise beyond the position shown in Figures 2 and 3. In use of the clip to secure together the diffuser and housing the clip section 16 is pushed upwards and inwards towards the housing and diffuser against a biasing force exerted by the torsion springs thereby to bring the lip section 21 into engagement with the overhang surface 21 of the housing. In this position the pivot position of the shanks 26 between the two clip sections 15, 16 lies in an over-centre position (see Figure 3) relative to the axis about which the first section is pivotally mounted to the housing, thereby firmly to retain the housing and diffuser in contact with one another. Although the spring as shown in Figure 8 provides a balanced force for the support of the second clip section 16, that is not an essential requirement and in a second embodiment of the present invention as shown in Figures 9 and 10 a spring 41 of a clip 40 may comprise a single coiled section 42. In both embodiments of the invention the torsion spring acts to ensure that when the clip is released from engagement with the diffuser the clip sections revert to the non-deployed position as shown in the right hand part of Figure 3 thereby automatically ensuring that the clip remains in a position sideways of the housing to facilitate unobstructed (re)positioning of the diffuser in engagement with the housing. Accordingly there is no requirement to carefully manually reposition the individual clips prior to initial fitting or refitting of a diffuser to a housing.

Claims

1. A luminaire comprising a removable cover which is securable to a light source housing by means of at least one over-centre type clip, said clip comprising a first section pivotally secured to the housing or diffuser and a second section pivotally secured to the first section and provided with a distal end formation adapted for engaging with a receiving section on the other of the housing and diffuser, the clip further comprising a spring which, prior to use of the clip to secure the diffuser to the housing, inherently acts to resiliently bias the two sections of the clip to reside in a predetermined orientation relative to one another, the second section being pivotable relative to the first section by applying a force to counteract the biasing effect of the spring for securing together the diffuser and housing.

2. A luminaire according to claim 1 wherein the spring is a torsion spring.

3. A luminaire according to claim 2 wherein the torsion spring comprises at least one coil of one or more turns of spring steel.

4. A luminaire according to claim 3 wherein the coil of the torsion spring has a major axis which is coincident with the axis about which the two sections of the clip are pivotable relative to one another.

5. A luminaire according to claim 4 and comprising two torsion springs the coils of which are spaced apart along said axis.

6. A luminaire according to claim 4 or claim 5 wherein at least one torsion spring comprises two end regions which extend outwards from the coil to bear respectively against the surfaces of the first and second clip sections.

7. A luminaire according to any one of claims 2 to 6 wherein at least one torsion spring comprises at least one end region which comprises a distalend portion that extends parallel with the axis about which the two sections of the clip are pivotable relative to one another.

8. A luminaire according to any one of claims 2 to 7 wherein the spring comprises two coils and the distal end portion of an end region of one coil is integral with the distal end portion of an end region of the other coil.

9. A luminaire according to claim 1 wherein the spring is a leaf spring.

10. A luminaire according to any one of the preceding claims and comprising stop means to restrict the angle of movement of the clip sections relative to one another under the action of spring force.

11. A luminaire according to any one of the preceding claims wherein when the spring is in a substantially unstretched condition the second section of the clip is supported by the spring in a position extending sideways and outwards from the position at which the diffuser is mounted into alignment with a confronting surface of the housing.

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