GB2123540A - Light fittings - Google Patents

Abstract

A light fitting for use with a compact, convoluted fluorescent tube light source has a support frame, a reflector 22 and a diffuser 30, each including a rectangular frame of extruded aluminium picture framing. The diffuser comprises a translucent, patterned acrylic sheet 34 overlying sheets 35, 36 of woven wire mesh or expanded metal, each anodized silver, red, gold, etc. The diffuser and reflector are held together by circular posts received in square tubes (26). A table lamp base is also described. This has decorative panels formed similarly to the diffuser 30 which are retained between lengths of extruded aluminium to be demountable for replacement by other decorative panels which match, for example, a light shade with which the lamp base is to be used. The lamp can use either a conventional bulb or a compact fluorescent tube. In the latter case, the choke for the base is located in a hollow central core of the lamp base. <IMAGE>

Description

SPECIFICATION Light fittings This invention relates to light fittings, for instance for domestic use, and is particularly concerned with fittings in which the light source is a low-consumption low heat output fluorescent lamp. Such lamps consist typically of a fluorescent tube, for instance, of about 12 mm diameter and an overall length of the order of 200-250 mm, which instead of being straight is bent upon itself into a compact shape with its axis in a plane, so that the two ends of the tube are adjacent and typically are connected to a central mounting member by which the lamp can be mounted in and secured to a lamp holder.The lamp gives a high light output for low current consumption over an area which is relatively large in relation to the diameter of the tube, for instance about 140-160 mm square, and also gives a much lower heat output than an incandescent electric bulb of similar rating.

A purpose of the present invention is to utilise the properties of the fluorescent lamps just described and to provide a light fitting, which is particularly suitable for instance for use as a domestic wall or ceiling mounted light, which has an effective, attractive, economical and practical construction.

The invention provides an assembly of sheet material comprising a sheet of translucent material overlying at least one sheet of perforated metal or metal-coated material. The assembly can form a diffuser for a light source and, because of the low heat output of the lamp itself, not only can an acrylic sheet be used in the diffuser but it can be positioned close to the lamp, so that the wall or ceiling light fitting can be of relatively compact dimensions. By the way of example, the light fitting can project from the surface upon which it is intended to be mounted by only about 60-80 mm, while having an overall area of, say, 300 mm x 400 mm.

The translucent sheet is preferably a patterned glass or acrylic sheet and the perforated metal or metal-coated sheet is preferably wire-mesh or expanded sheet metal, more preferably formed of light-coloured anodized aluminium. It has been discovered that a particularly attractive effect is given if one or two such metal sheets are disposed over the lamp in association with a patterned translucent sheet. A particularly useful combination consists of a translucent plastics sheet diffuser component and one or two perforated metal diffuser components, e.g. a regularly-patterned acrylic sheet having its rear face, namely the face nearer to the lamp, in surface contact with one of two superposed sheets of gold or silver anodized expanded aluminium sheet or similarly anodized aluminium wire mesh.

It has also been found that the combination of translucent sheet material and perforated metal or metal-coated material which the invention provides gives a pleasing decorative effect even when not lit from behind. This decorative effect can be utilised to provide a decorative panel of a light fitting, preferably a panel of a base of a table lamp.

The invention also provides a light fitting having at least one decorative panel, for example a panel mentioned above, which is demountable for replacement by a further panel of different appearance. In this way, a light fitting, for example a table lamp base, of which the appearance can be changed according to the lamp shade to be used or the decor of the room in which the fitting is to be used, is provided.

Another preferred feature of the invention is a principle of construction of a light fitting, the fitting comprising a reflector and a diffuser, with a convoluted compact fluorescent tube light source of the above-mentioned kind located between the reflector and the diffuser. The latter may be attached to the reflector by interfitting post and tube means, preferably in association with resilient retention means which enable the diffuser to be readily attached to or removed from the reflector, for instance when it is desired to replace the lamp. Advantageously, the fitting includes a generally-planar base member behind the reflector and supporting the light source through an aperture in the reflector.

A further advantageous feature of the invention is that the components of the light fitting are made in square or rectangular format and each or all of the base, the reflector and the diffuser can consist of a set of lengths of extruded metal e.g.

aluminium framing, mitered and secured together in picture-frame fashion so that sheet metal fabrication techniques are eliminated in the construction of the light fitting of the invention.

Extruded metal framing of this type can also be made use of in a table lamp base according to the present invention, this base has at least one decorative panel, preferably an assembly of sheet material mentioned above, which is retained along opposite edges behind respective lengths of extruded metal.

In order that these and other features of the invention can be readily appreciated and understood, embodiments of the invention are described below, by way of illustration, in conjunction with the drawings, in which: Fig. 1 shows a partial elevational view of a base member for a light fitting; Fig. 2 shows a partial elevational view of a reflector, to be attached to the base member of Fig. 1, and a cooperating diffuser attached to the reflector; Fig. 3 shows a part-elevational part-sectional view of the base member, reflector and diffuser of Figs. 1 and 2, on the line Ill-Ill of Fig. 2; Fig. 4 shows a cross-section of a lamp holder arrangement on the line lV-lV of Fig. 1; Fig. 5 shows a cross-section of the diffuser mounting arrangement, on the line V-V of Fig. 2;; Fig. 6 is a side elevation of a table lamp base of which a portion at the right-hand side is shown in section; and Fig. 7 is a horizontal section on the line VIll-VIll of Fig. 6.

Referring to Fig. 1, a base member 1 consists of a frame 2 comprising four lengths of aluminium picture-frame extrusion, three of which are indicated at 2a, 2b and 2c, having their corners mitered and joined together in conventional fashion by L-shaped mounting members, one of which is shown at 3. The members 2a to 2c forming the frame 2 have the appropriate crosssection (see Fig. 3) to allow the various other components of the base member 1 to be mounted on the frame 2. The frame 2 forms a ballast case for the light fitting and supports a cover, indicated generally at 4, a base plate 5 being attached to a lower part of the base member 1 and receiving the usual connecting member 6 for the electrical supply wires (not shown) and the wiring connections (also not shown) of the lamp itself, together with an on/off pull switch 7 having a cord 7a.In order to secure the base member 1 and thus the whole light fitting to a wall surface or a ceiling surface, a pair of opposed metal brackets 8 are attached diametrically across the frame 2 of the base member 1. Each bracket 8 is in the form of an L-section metal plate, the inner ends of these plates supporting a central bridge plate 9, described in further detail below. The brackets 8 have their main parts at the rear face of the base member 1 The bracket 8 on the left includes a horizontal mounting slot 10, while that on the right includes a vertical mounting slot 11, so that the base member 1 and therefore the light fitting can be readily secured to a surface by two screws plugged into the surface through the mounting slots 10, 11, which also provide for a desirable degree of adjustment of the light fitting in conventional manner.The open back of the base member 1, constructed as described above, allows considerable flexibility in positioning the light fitting relative to the exposed end of an available power supply, as the mains wires can be brought into the base member 1 and so attached to the connecting member 6, at many places within the base member 1.

As shown in more detail in Fig. 4, the bridge plate 9 supports a socket 12 for receiving the connecting pins (not shown) of the lamp, indicated at 13 in Figs. 2 and 3. Figs. 1 and 4 show that the socket 12 is mounted within a corresponding aperture 14 in the bridge plate 9, in which it is retained by means of a curved PTFE strip 1 5 secured to the underface of the bridge plate 9 by screws 1 6 and curved through the aperture 14, so as to provide a spring force holding the lamp 1 3 firmly in place. Each screw 1 6 projects forwardly from the bridge plate 9 and carries a P-clip 18, each used to secure one of the insulated wires (not shown) connecting the lamp socket 12 to the connecting member 6.

Referring to Figs. 1 and 3, the base member 1 receives and supports the remaining parts of the light fitting, whilst allowing good ventilation and heat dissipation because of its open construction, the remaining parts of the light fitting comprising a reflector 22 and a diffuser 30. The reflector 22 comprises a frame 23 formed of lengths of extruded aluminium picture-framing 23a to 23d which are mitered and secured to one another by conventional means, as described above for the frame 2 of the base member 1. Within the reflector frame 23 so formed, an acrylic base sheet 24 is mounted to which the lamp 13 is centrally secured. The base sheet 24 is held in place by leaf springs (not shown) which press the sheet 24 forwardly in the frame 23 in known manner.At four spaced locations towards its corners, the base sheet 24 contains holes (not shown in Fig. 2), each of which receives a hexagonal bolt, one of which is shown at 25 in Fig.

5. Further holes made in the sheet 24, within the periphery of the base member 1, register with holes 29 (Fig. 1) made in the members forming the frame 2. Nylon screws 28 (Figs. 2 and 3) secure the reflector 22 (and therefore the diffuser 30 attached to it) to the base member 1. On the exterior of the base sheet 24, these bolts 25 are fixedly secured within square-section brass tubes 26. It has been found that an adequately firm securement can be obtained by tapping the tube 26 and matching each bolt 25 with the internal size of the tapped tube 26. By these simple means, the four pieces of brass tube 26 project forwardly in a firm and rigid manner from the selected locations towards the corners of the acrylic base sheet 24.Centrally, at the upper and lower parts of the base sheet 24, a wire spring 27 is mounted in spaced holes formed in the base sheet 24 for this purpose.

The other main component of the light fitting is the rectangular diffuser 30 which, like the base member 1 and the reflector 22, also consists of a frame 31 formed of four lengths of aluminium extrusion, three being shown at 31a to 31c, mitered and joined together by means of connecting members in picture-frame fashion. The diffuser 30 thus resembles a framed picture when mounted in place on a wall. Within the rectangular frame 31 so formed, the diffuser 30 comprises three main light-effecting components, which again can be held in place by picture-glass leaf springs (not shown). The external component comprises a translucent acrylic sheet 34, which preferably has a relatively small regular geometrical pattern as indicated diagrammatically at 34a in Fig. 2. Beneath this, i.e. nearer to the lamp 13, is a first perforate metal diffuser component 35, which preferably consists of a woven wire mesh or expanded metal mesh of silver, white, red or gold coloured anodized aluminium, as indicated diagrammatically at 35a.

A silver-coloured diffuser element 36 is located beneath the component 35 and again consists of wire mesh or expanded metal, as indicated diagrammatically at 36a. It has been found that one or two such metal diffuser components 35, 36 together with a translucent acrylic diffuser sheet 34, provide an attractive and effective diffusing of the light from the lamp 13, the low heat output of which has no adverse effect upon the acrylic sheet 34 of the diffuser 30 nor on the acrylic base sheet 24 of the reflector 22.

Moreover, the apertures in the woven mesh or expanded metal constituting the diffuser components 35 and 36 cooperate with the pattern components of the preferably geometrically-repeating pattern of the acrylic diffuser sheet 34 to enhance this attractive and pleasing effect.

At the corners of the frame 31 of the diffuser 30, round-headed screws, one of which is indicated at 37 in Fig. 5, are mounted in tapped holes 39 and the exposed part of the screw thread is preferably surrounded by an appropriately sized length of metal or other tube 38. The screws 37 and tubes 38 thus form upstanding posts and the components are selected so that these posts are a convenient push fit in the square-section metal tubes 26 attached to the bolts 25. The leaf springs 27 are located on the acrylic base sheet 24 of the reflector 22 so that each bears inside the respective upper or lower components 31 a and 31 c of the frame 31 of the diffuser 30, as indicated in Fig. 3.The diffuser 30 is detachably mounted on the reflector 22 by positioning the heads of the screws 37 in the square brass tubes 26, the leaf springs 27 providing a further securing force, so that the entire diffuser 30 can be readily mounted in the correct position on the exposed face of the acrylic base sheet 24 of the reflector 22 and also can be equally readily removed from it.

The light fitting can also provide further attractive effects. For instance, if the diffuser component 34 is adjacent a fine expanded metal sheet, this can have a one-colour or multi-colour silhouette or picture applied to it, e.g. by stencilling or screen-printing. Where this picture is visibie when the light fitting is not in use, the strong back-lighting of the mesh given when the lamp 13 is lit causes the picture to disappear.

Thus, the fitting behaves as a picture in the daytime and as a wall-light in the evening.

Another attractive effect can be obtained by placing a decorative material e.g. a fibreglass fabric having a design or picture woven into it, between the acrylic diffuser sheet 34 and a second translucent sheet, e.g. of glass.

In a modified version of the light-fitting described above, the L-shaped brackets 8 and the base plate 5 are dispensed with an enlarged base plate closes-in completely the back of the fitting inside the frame 2. The enlarged base plate supports the connecting member 6 and the switch 7 in the same way as the base plate 5 shown in figure 1 and also supports a socket-support member corresponding to the central bridge plate 9. The socket-support member is attached to, and spaced from, the enlarged base plate by a pair of parallel aluminium rods attached at their ends to the socket-support member and the enlarged base plate. Suitably-positioned mounting slots and an aperture for the mains wires to pass through are formed in the enlarged base plate.

A second modified light-fitting, which may also incorporate an enlarged base plate as described above and which is particularly suitable for use as a ceiling light, has two sockets for receiving two lamps of the same type as the lamp of figure 2.

The sockets are, for example, at 140 mm centres and supported on two separate, or one common, bridge plate or support member of the types described above. The left-hand (when viewed from the front) one of the two lamps is rotated through 900 clockwise compared with the lamp of figure 2 and the right-hand one rotated through 900 anticlockwise. This two-lamp light fitting has a reflector which is about 33 cm wide and 31 cm high, whilst the diffuser has a width of about 32 cm and a height of about 23 cm. To support the enlarged diffuser, four wire springs 27 are used and these are spaced-apart by about 25 cm along the upper and lower edges of the diffuser.

By way of further modification, the base sheet 24 of the light fittings described can be made from epoxy-coated aluminium sheet, rather than acrylic sheet material.

The table lamp base shown in figures 6 and 7 has a plinth 48 formed from a frame consisting of four mitred pieces of aluminium picture framing 50a, 506, 50c, and 50d, connected together by Lshaped brackets (not shown) similar to the brackets 3 shown in figure 1, and a metallic plate 52 which forms the upper surface of the plinth 48 and is retained in the frame 50 by conventional leaf springs (also not shown).

The plate 52 is secured by four screws 53 to a central square-section hollow core 54, the screws 53 passing into short lengths of square-section tube 55 screwed to the outer surface of the core 54 at its lower end. The core 54 has screwed to it eight lengths 56a, 56b, 56c, 56d, 56e, 56f, 56g, and 56h of aluminium picture frame extrusion, two to each of its faces.

The pair of lengths of picture framing 56 attached to each face of the core 54 receive between them a strip 57 of transparent acrylic sheet material, similar to the material 34 of figure 2, and, behind the strip 57, a further strip 58 of mesh material, similar to the material 35 or 36 of figure 2. The strips 57, 58 are retained by conventional picture-framing leaf springs 60 and have been found to produce a pleasing decorative appearance, even without illumination from behind.

Instead of the mesh material 58, a strip of fabric or other decorative material can be placed behind the translucent strip 57, if necessary with a further supporting strip behind it.

The appearance of the table lamp can thus be readily changed by removal and insertion of strips 57, 58, or strips of fabric or other decorative material of different appearance, for example to match the appearance of the table lamp to a particular light-shade with which it is to be used or to the decor of a room in which it is to be used.

The base 48 is completed by a top plate 62 which is secured by screws 63 and short lengths of square-section rod 64, secured to two opposite faces of the core 54. The top plate 62 supports a lamp holder 65 which may be one for a conventional tungsten bulb, or one for a convoluted fluorescent tube of the type described above. In the latter case, the choke 66 for the convoluted tube can be accommodated in the hollow of the core 54 and the conversion of the lamp from use with one type of lamp to the other is facilitated.

The use of demountable panels or strips of different appearance is not limited to table lamp bases of the kind described but can also be made in connection with any type of light fitting.

Claims (24)

1. An assembly of sheet material comprising a sheet of translucent material overlying at least one sheet of perforated metal or metal-coated material.

2. An assembly according to claim 1, in which the translucent sheet is patterned.

3. An assembly according to claim 1 or claim 2, in which the translucent sheet is of acrylic material.

4. An assembly according to any preceding claim, in which the perforated sheet is of anodized expanded aluminium.

5. An assembly according to any one of claims 1 to 3, in which the perforated sheet is anodized aluminium wire mesh.

6. A diffuser for a light source, at least a portion of the diffuser being an assembly of sheet material according to any preceding claim.

7. A light fitting having at least one decorative panel formed by an assembly according to any one of claims 1 to 6.

8. A light fitting comprising a reflector, a diffuser, and a convoluted compact fluorescent tube light source located between the reflector and the diffuser.

9. A light fitting according to claim 8, in which the reflector and the diffuser are each substantially planar.

10. A light fitting according to claim 9, including a generally-planar base member behind the reflector and supporting the light source through an aperture in the reflector.

11. A light fitting according to any one of claims 8 to 10, in which the diffuser is demountably attached to the reflector by interfitting post and tube means.

12. A light fitting according to claim 11, including resilient biassing means enhancing retention of the diffuser on the reflector.

13. A light fitting according to claim 11, in which the post and tube means comprise at least one tube having a square internal cross-section and an interfitting post of circular external crosssection.

14. A light fitting according to any one of claims 8 to 13, in which the diffuser is in accordance with claim 6.

1 5. A light fitting comprising at least one framework comprising interconnected lengths of extruded metal.

16. A light fitting according to claim 9 or claim 10, in which at least one of the reflector and the diffuser comprises a framework according to claim 15.

1 7. A light fitting according to claim 10, in which the base member comprises a framework according to claim 1 5.

1 8. A light fitting having at least one decorative panel formed by an assembly according to any one of claims 1 to 5.

19. A light fitting according to claim 18, the light fitting being a table lamp base and the panel a portion of the base.

20. A light fitting according to claim 19, in which the panel is retained along opposite edges behind respective lengths of extruded metal secured to the base.

21. A light fitting according to claim 1 9, in which the base has a central core of polygonal cross-section and a plurality of rectangular faces, a said panel being secured to each face of the core by lengths of extruded metal secured along opposite edges of each rectangular face.

22. A light fitting according to claim 21, in which the core is of square cross-section and receives removably a choke of a fluorescent light source.

23. A light fitting having at least one removable decorative panel which is demountable for replacement by a further panel of different appearance.

24. A light fitting substantially as hereinbefore described with reference to figures 1 to 5, or figures 6 and 7 of the drawings.