GB2300470A - A reflector unit for a light fitting - Google Patents

Abstract

A light reflector comprising a plurality of first parts each defining a respective locking aperture, and at least one second part to which the first parts are connected, each first part passing through at least one attachment aperture defined by the second part of the reflector and being prevented from passing back through the or each attachment aperture by a locking piece which passes through and is common to a plurality of the said locking apertures. Also a light fitting for recessed mounting in a surface comprising a backing plate, and a removable light reflector for mounting adjacent the backing plate the reflector being in contact with the backing plate such that the reflection portion and backing plate in combination form a continuous reflecting surface. Also a light fitting for recessed mounting in a planar surface, including a light reflector for reflecting light produced by a light source mounted to the fitting, and having at least one reflection element which in use, extends out of the recess beyond the plane of the planar surface thereby to reflect light back onto the planar surface.

Description

A LIGHT REFLECTOR The present invention relates to a light reflector and in particular to such a reflector for use with a light fitting.

It is becoming common, particularly in work environments, to provide fit a light fitting with a reflector. The purpose of such a reflector is usually to improve the lighting efficiency which is achieved mainly by directing the majority of the light from the light fitting downwards towards the area to be lit, and to reduce the surface brightness or glare of the light assembly. The latter purpose is usually carried out by providing the reflector with periodically spaced elements giving a particular cutoff angle in use ie. an angle measured from the vertical at which the illumination from the light assembly is below a particular brightness level. One standard used in the lighting industry specifies that at a cut-off angle of 65 , the surface brightness of the assembly must be less than 200 candelas per square metre.In practice, such a requirement is usually met by ensuring that the spaced elements prevent the light source from being directly visible at angles greater than the cut-off angle.

In some environments control of glare is a mandatory requirement and thus there is a need for light fittings to be fitted with suitable reflectors.

A typical known reflector is constructed from aluminium and comprises an aluminium outer wall forming a main reflector and periodically spaced cross-blades to bring the glare of the fitting into acceptable limits. Such a reflector is expensive to manufacture since it requires accurate machining and folding processes to be used. Furthermore the reflector must be handled carefully at all stages from manufacture to fitting since grease and perspiration marks from fingerprints etch the anodized surface of the reflector causing unsightly marks and reducing its reflection efficiency. Thus, such a reflector is usually handled only using gloves. Furthermore, an aluminium reflector is sufficiently heavy that it is usually necessary to replace an entire light fitting in order to provide suitable fixing points for a reflector.For this reason it is usually not possible to fit such a reflector to an existing light fitting.

A partial solution to the above problems has been found in the use of a reflector constructed from a laminated plastics material including a thin layer of aluminium located in one of the inner laminate layers. Such a material is lighter and less prone to marking than aluminium. A light reflector for a single fluorescent tube constructed from this material is available. It comprises a generally U-shaped rear reflector which when in place is arranged around the fluorescent tube such that the tube is located at the base of the U. It includes a series of periodically spaced cross-blades which lie transversely of the longitudinal axis of the tube and which serve to control the cut-off angle of the assembled reflector and light fitting in the longitudinal direction. The cross-blades have tongues at each end which pass through respective apertures in the Ushaped reflector.The apertures include locking portions which extend from the side of each aperture and pass through slots formed in the tongues to prevent the tongues pulling back through the aperture.

The construction of this reflector is complicated and it is consequently expensive to manufacture.

Alternative construction techniques for light reflectors are known from aluminium reflectors. Typically such techniques involve passing a tab or tongue through a generally circular hole in another part of the reflector and then bending the tab over to prevent it pulling back through. Such techniques are unsuitable for use with laminated plastics materials since they are generally too elastic and the folded-over tab therefore does not remain folded over.

Similar problems occur when using wing clips. Other conventional techniques used with metals such as riveting and screwing are also unsuitable for use with laminated plastics materials since these techniques cause the material to tear.

Consequently, although plastics laminated materials are known to have certain advantages over, for example, aluminium for use in a light reflector, laminate material presents difficulties in fastening parts together in a way which is both secure and economical in manufacture.

It is an object of the present invention to overcome at least some of the problems of prior reflectors.

According to one aspect of the invention, a light reflector comprises a plurality of first parts each defining a respective locking aperture, each first part passing through at least one attachment aperture defined by a second part of the reflector and being prevented from passing back through the or each attachment aperture by a locking piece which passes through and is common to a plurality of the said slots.

By arranging for a locking piece to pass through each slot, the manufacturing process is simplified and is therefore reduced in cost. This is because once the first parts have been passed through the second part, a single operation is required to insert the locking piece through each slot.

It will be appreciated that at least one of the first parts may be integral with the second part.

Preferably the reflector includes elements constructed from a resiliently flexible material. This may, for example be a metallised polyester PVC film laminate, particularly a laminate in which two plastics layers sandwich a layer of aluminium. The thickness of the aluminium may be between 2 and 7 micro-meters and is typically 3 micrometers. The thickness of the complete laminate is preferably between 200 and 500 micrometers, with 300 micro-meters being a typical figure. Such a laminate is both lightweight and highly reflective and is thus suitable for application in the field of light reflectors.

Preferably the first parts are tongue portions extending from an edge of an element of the reflector. Using this particular construction, the edge of the first part may abut the surface of the second part which surrounds the aperture thereby forming a shoulder which can be used to prevent the first part passing further through the aperture than is required. If the slot is then located in the tongue away from the edge by a distance substantially equivalent to the thickness of the second part, then the first part once secured with the locking piece has virtually no freedom of movement in a direction generally into and/or out of the aperture.

Preferably the first parts are longitudinal members, hereinafter referred to as long-blades, and the second part is an end cap. The long-blades typically extend generally parallel to a longitudinal axis of the reflector and/or light fitting to which the reflector is fitted. Typically also, the end cap forms a generally opaque and possibly reflective transverse element at each end of the reflector.

Alternatively, the first parts may be transverse members, hereinafter referred to as cross-blades, and the second part may be an edge fin or wall. The cross-blades are typically arranged perpendicular to the long-blades and therefore extend transversely of the reflector (parallel to the end caps) and are located in an edge fin which extends parallel to a long-blade at an outer edge of the reflector.

As a further alternative, the first parts may be long-blades and the second part may be a cross-blade or vice versa.

It will be appreciated that the slot may be formed anywhere on each first part or second and need not be at or near an edge of the part.

It will also be appreciated that the locking piece may take any form which conveniently passes through the slot and which thereby prevents each first part from passing back through the aperture. Typically, however, the locking piece will be generally elongate and advantageously may be a generally planar strip which may be constructed from the same material as the reflector. In its locking position, the locking piece may lie in a plane generally parallel to the plane of the second part.

Preferably at least one of the parts is reflective.

In a reflector made from a resiliently flexible material, and having cross and long-blades, the cross and long-blades may be constructed from lengths of material which form the whole member or blade and which are arranged to interlock to form a grid. Typically a first one of the blades is arranged on its upper surface to have wing portions extending transversely of the blade and which may be inserted inside a second one of the blades which extends transversely of the first blade. Such wing portions may be formed by cutting the material in a closed shape one side of which shape is formed by a line of weakness in the material.

When the material is folded along the line of weakness the material within the closed shape is caused to fold out of the original plane of the material into the plane of the folded material.

Once the wing portions are inserted in the second blade, the second blade is prevented from sliding along the first blade.

According to a further aspect of the invention, a light fitting for recessed mounting in a surface comprises a backing plate and a removable light reflector for mounting adjacent the backing plate, the reflector being in contact with the backing plate such that the reflection portion and backing plate in combination form a continuous reflecting surface.

Preferably the reflector is constructed from a resiliently flexible material. Thus in a "lift and tilt" application where the reflector must be lifted and rotated to remove it from the support struts of a suspended ceiling, the reflecting elements of the reflector may extend fully into the recess since they will flex when the reflector is lifted. In the prior art aluminium reflector this was impossible since the material would not flex and therefore the reflector could not be inserted or removed from the backing plate if the reflectors extended fully into the recess. By providing a continuous reflecting surface, reflection efficiency can be improved by up to 20%.

Preferably the light fitting is arranged for fitting to an elongate light source. In this case, the reflecting surface may be elongate and may extend at least partially along the longitudinal axis of the fitting. The reflecting surface may have a generally parabolic cross-section.

According to a yet further aspect of the invention, a light fitting for recessed mounting in a planar surface includes a light reflector for reflecting light produced by a light source mounted to the fitting and has at least one reflection element which in use, extends out of the recess beyond the plane of the planar surface thereby to reflect light back onto the planar surface.

In this way, the so-called tunnel effect is minimised whereby the planar surface (typically a ceiling) itself is illuminated rather than the surface appearing dark with several small areas of bright light formed by the reflector and light source.

The invention will now be described by way of example with reference to the drawings in which: Figure 1 is a transverse section through a light fitting with a reflector in accordance with the invention; Figure 2 is a plan view of an unfolded end cap in accordance with the invention; Figure 3 is a plan view of an unfolded cross-blade in accordance with the invention; Figure 4 is a plan view of an unfolded long-blade in accordance with the invention; Figure 5 is a plan view of an unfolded edge fin in accordance with the invention; Figure 6 is a sectional view of a light fitting for a recessed mounting in accordance with the invention; and Figure 7 is a perspective view of a reflector assembled to a light fitting in accordance with the invention.

Figure 1 shows a reflector 2 having long-blades 4, crossblades 6 (in the view of Figure 1 only one cross-blade can be seen) and edge-fins 8.

The reflector is shown fitted to a fluorescent batten 10 upon which are mounted two fluorescent tubes 12.

With reference also to Figure 2, at the far end of the reflector 2 an upper portion 14A of an end cap 14 is visible behind the cross-blades 6.

The individual elements making up the reflector 2 are each made from planar sheets of plastics laminate material including an aluminium layer as described above. They are formed by cutting and folding the material in the manner described in detail below.

With reference to Figure 2, the end cap 14 in addition to the upper portion 14A described above includes a lower blade portion 14B which is formed by folding the material along the dotted lines 16A, 16B, 16C shown in the figure.

In each case, the fold is made in the same direction and when fitted to the other components, the fold angle (ie the internal angle made between the planes of the material on either side of the fold line) are approximately 170 , 10 and 90 for fold line 16A, B and C respectively. Thus, the end cap when assembled has a generally planar portion 14A which extends into the portion between lines 16A and B with a small change in angle. Along side the portion between lines 16A and 16B is the portion between the lines 16B and 16C which is almost doubled back to lie in a narrow-angled V formation close to the portion between lines 16A and 16B.

The planar portion of the end cap lies on the outside of the reflector. Thus, the end cap forms a generally opaque cap which prevents light exiting through the ends of the reflector 2 and also prevents the unfinished parts of the light fitting being viewed. The blade portion formed by the material between lines 16A and 16C form what is in effect a terminal version of a cross-blade.

The end cap also has tongues 18 which include slots 20. The tongues 18 pass through corresponding apertures in the edgefins 8 as described below.

With reference to Figure 3, the cross-blade 4 is similar in construction to the lower portion 14B of the end cap. As will be seen, it also has tongues 18 with slots 20 for insertion in a corresponding aperture in the edge-fins 8.

It also has three fold lines 22A, 22B, 22C and when constructed the fold angle about line 22B is similar to that about line 16B. The fold angles about lines 22A and 22C are approximately 90 and as in the case of the end cap, the folds are all in the same direction.

Turning again to the tongues 18 and slots 20, it will be seen with reference for example to Figure 1, that the tongue 18 and therefore the cross-blade 4, can be secured to the edge fin 8 by passing a locking piece (not shown) through each of the slots 18. The locking piece is typically a strip of the plastics laminate material from which the reflector is constructed, of a width corresponding to the length of the slot 18.

With reference also to Figure 4, the cross-blade 4 includes a further slot 24 which it will be appreciated when the blade 4 is folded, forms a V-shaped slot in which the base of the V is truncated.

The long or centre V-blade is folded in the same manner as the cross-blade about fold lines 26A, 26B and 26C respectively. The long-blade 6 also has slots 28 which receive the cross-blade 4. The dotted line 30 beneath the left most slot 28 indicates where the edges of the slot 24 lie against the outer surface of the long-blade 6.

The closed shape 32 formed by cutting on three sides (the fourth side being made by the fold line 22A) into the crossblade 4, forms a locating wing portion. When the cross blade 4 is folded, the wing portion lies in the plane of the portion above line 22A and below line 22C respectively. The wing portions 32 are locatable between the flaps formed by fold lines 26A and 26C of the long-blade 6, and the shoulders 34 formed in the slots 28. The wing portions 32 serve to prevent the cross-blades 4 from sliding along the long-blades 6.

In the embodiment described, it will be seen from the number of slots 24 formed in the cross-blade 4 that only two longblades are provided. It will be appreciated that the number of long-blades may be varied according to requirements for the reflector and in particular to the cut-off angle required. Furthermore it will be seen from Figure 4 that the long-blade is not shown in its full length and the number of cross-blades will be understood to vary depending on the length of the light fitting and also on the required cut-off angle.

Figure 3 also shows on its right side, a different construction for the area of the slot 24. This construction does not produce a wing portion 32 but relies instead on a tab 36 being located between shoulders 34. A similar construction is seen in Figure 2 where the end cap forms in its lower blade portion 14B a terminal cross-blade having locating portions based around a slot 28.

Although not shown in Figure 4, the long-blade 6 may have a tongue 18 and slot 20 arrangement similar to that provided on the cross-blade 4 and end cap 14.

Figure 5 shows a plan view of an edge-fin 8 at approximately half the scale of the other components. Fin 8has slots 38 for receiving tabs 40 formed on the left and right edges of the upper portion 14A of the end cap 14. The edge-fin 8 also includes apertures 40A and 40B for receiving the tongues 18 of the cross-blades 4 and end cap 14.

The edge fin 8 has fold lines 42A, 42B, 42C. The angles at which folds are made along these lines can be seen from Figure 1. Again, the folds are made in the same direction and the fold angles about lines 42A and 42C is about 90".

Figure 6 shows a reflector for fitting in a recess in a suspended ceiling. It comprises elongate generally parabolic reflectors 50 which in combination with a backing plate 52 form a reflecting surface which extends behind two elongate light sources (typically fluorescent tubes) the centres of which are indicated by lines 54. As will be seen, the reflectors 50 abut the backing plate 52. Since the material from which the reflectors 50 are constructed is resiliently deformable, the reflectors 50 may be pushed up against the backing plate in order to allow "lift and tilt" insertion and removal of the reflector from an aperture in the suspended ceiling. The ceiling is indicated by an adjacent ceiling tile 56 and a T-shaped support 58.

In another embodiment, the reflectors 50 may extend beyond the plane of the ceiling in order to cause light to reflect back onto the ceiling. The extended portion is shown in the drawing with reference numeral 60. In the preferred embodiment the extended portion continues the parabolic shape of the reflector 50.

Figure 7 shows a complete reflector and light assembly in accordance with the invention.

Claims (16)

1. A light reflector comprising a plurality of first parts each defining a respective locking aperture, and at least one second part to which the first parts are connected, each first part passing through at least one attachment aperture defined by the second part of the reflector and being prevented from passing back through the or each attachment aperture by a locking piece which passes through and is common to a plurality of the said locking apertures

2. A reflector according to claim 1, wherein at least one of the first parts is integral with the second part.

3. A reflector according to claim 1 or claim 2, wherein the reflector includes elements constructed from a resiliently flexible material.

4. A reflector according to any preceding claim, wherein the first parts are tongue portions extending from an edge of an element of the reflector, and the locking apertures are slots.

5. A reflector according to any preceding claim, wherein the first parts are cross members and the second part is an edge fin or side wall, generally perpendicular to the cross-members.

6. A reflector according to any of claims 1 to 4, of elongate configuration wherein the first parts are longitudinal members and the second part is an end cap generally perpendicular to the longitudinal members.

7. A reflector according to any of claims 1 to 4, wherein the first parts comprise a plurality of fins which are parallel to each other and the second part is a cross fin which is perpendicular to the said plurality of fins.

8. A reflector according to claim 7, wherein the said fins are located between outer members associated with or forming the periphery of the reflector.

9. A reflector according to any preceding claim, wherein at least one of the first and second parts is reflective.

10. A light fitting for recessed mounting in a surface, comprising a backing plate, and a removable light reflector for mounting adjacent the backing plate the reflector being in contact with the backing plate such that the reflection portion and backing plate in combination form a continuous reflecting surface.

11. A light fitting for an elongate light source, the light fitting being constructed according to claim 10.

12. A light fitting according to claim 11, wherein the reflecting surface is elongate and extends at least partially along a longitudinal axis of the fitting.

13. A light fitting according to any of claims 10 to 12, wherein the reflecting surface has a generally parabolic cross-section.

14. A light fitting for recessed mounting in a planar surface, including a light reflector for reflecting light produced by a light source mounted to the fitting, and having at least one reflection element which in use, extends out of the recess beyond the plane of the planar surface thereby to reflect light back onto the planar surface.

15. A light reflector constructed and arranged substantially as herein described with reference to the drawings.

16. A light fitting constructed and arranged substantially as herein described with reference to the drawings.