GB2202039A

GB2202039A - An improved electric lighting fitting

Info

Publication number: GB2202039A
Application number: GB08802469A
Authority: GB
Inventors: Robert John Mee
Original assignee: BICC PLC
Current assignee: Balfour Beatty PLC
Priority date: 1987-02-05
Filing date: 1988-02-04
Publication date: 1988-09-14
Anticipated expiration: 2008-02-04
Also published as: GB8702549D0; GB2202039B; GB8802469D0

Abstract

An inexpensive electric lighting fitting especially suitable for use in mines comprises a transparent or translucent sleeve 1 containing a holder for an elongate tubular lamp and closed at each of its ends by an end wall 5 which is separately formed with respect to and is detachable from the sleeve. A tubular casing 2 of plastics insulating material extends alongside the sleeve 1 intermediate its ends and houses equipment associated with the lighting fitting, the tubular casing being closed at each of its ends by an end wall 6 separately formed with respect to and detachable from the casing. Extending between the sleeve 1 and tubular casing 2 throughout the length of the sleeve, is an elongate member 7 having, nearer the sleeve, a light reflecting surface. Manufacturing costs are substantially less than those of comparable lighting fittings. <IMAGE>

Description

AN IMPROVED ELECTRIC LIGHTING FITTING This invention relates to electric lighting fittings for elongate tubular lamps, such as fluorescent tubes, and is especially, but not exclusively, concerned with electric lighting fittings of this kind which are suitable for use in locations where there is risk of ingress of water and/or dust and other small solid foreign bodies and where an explosive atmosphere may be present.

It is an object of the invention to provide an improved electric lighting fitting of this kind which is simple in form and inexpensive to manufacture.

According to the invention the improved electric lighting fitting comprises a sleeve of transparent or translucent material which contains at least one holder for an elongate tubular lamp and which is closed at each of its ends by an end wall which is separately formed with respect to and is detachable from the sleeve; a tubular casing of electrically insulating material which extends alongside the sleeve over at least a part of the length of the sleeve and houses equipment associated with the lighting fitting (which equipment is generally and hereafter will be referred to as "ballast") , the tubular casing being closed at each of its ends by an end wall, at least one of which end walls is separately formed with respect to and is detachable from the tubular casing; and, extending between the sleeve and the tubular casing throughout substantially the whole of the length of the sleeve, an elongate surface of a light reflecting material.

The tubular casing of electrically insulating material may be of substantially the same length as the sleeve of transparent or translucent material and, in this case, may also house control gear for emergency use. Where the tubular casing extends only over a part of the length of the sleeve, preferably it is positioned intermediate the ends of the sleeve; alternatively, it may be positioned near one end of the sleeve with the adjacent end walls of the sleeve and casing lying alongside one another and, in this case, a second tubular casing of electrically insulating material may extend alongside, and over a part of the length of, the sleeve near the other end of the sleeve, the second casing housing control gear for emergency use.One end wall of the or each tubular casing may be an integral part of the casing or both end walls of the or each tubular casing may be separately formed with respect to and readily detachable from the casing.

Preferably, the end walls of the sleeve of transparent or translucent material are also separately formed with respect to the tubular casing or tubular casings but, in some circumstances, one or each of the end walls of the sleeve may be integral with the adjacent end wall of the tubular casing or one of the tubular casings or it may be integral with a side wall of the tubular casing or one of the tubular casings.

In all cases, where an end wall is separately formed with respect to the associated sleeve or tubular casing, a peripherally continuous fluid-tight sealing ring is provided between the sleeve or tubular casing and the end wall, The elongate surface of a light reflecting material extending throughout substantially the whole of the length of the sleeve between the sleeve and the tubular casing or tubular casings may be a surface nearer the sleeve of an elongate member which is separately formed with respect to the sleeve and tubular casing or casings and, in this case preferably the elongate member has on its surface remote from the sleeve one or more than one longitudinally extending strengthening rib which may serve the additional purposes of a means with which a part of the or each tubular casing may interengage and, where an intermediate length of the or each strengthening rib is exposed between two tubular casings, may serve as a means to which can be secured separately formed components for mounting the lighting fitting to a ceiling, wall or other surface. Alternatively, where a single tubular casing extends throughout substantially the whole length of the sleeve, the elongate surface of a light reflecting material may be carried by the tubular casing.

The or each tubular casing may also have throughout at least a part of its length at least one internal longitudinally extending strengthening rib along which can be slidably engaged a support plate on which the ballast and/or control gear for emergency use can be mounted. The or each tubular casing may also have on the side wall of the casing remote from the sleeve at least one external longitudinally extending strengthening rib which may also serve as a means to which can be secured separately formed components for mounting the lighting fitting on a ceiling, wall or other surface.

The sleeve for housing the or each tubular lamp preferably is of extruded transparent or translucent plastics material. Where the end walls of the or each tubular casing are separately formed with respect to the casing, the tubular casing preferably is of an extruded electrically insulating plastics material. Where one of the end walls of the or each tubular casing is integral with the casing, preferably the casing is made of moulded electrically insulating plastics material. The elongate member having said light reflecting surface preferably is an extrudate of metal or metal alloy, e.g.

aluminium or sheet steel, or of electrically insulating plastics material. Each separately formed end wall of the sleeve and tubular casing or tubular casings preferably is made of moulded electrically insulating plastics material.

By virtue of the fact that the sleeve and elongate reflecting member, and in some circumstances, the or each tubular casing, can be made by extrusion and cut to any required length, manufacturing costs of the improved lighting fitting are substantially less than those of lighting fittings of the kind hitherto proposed and used. Furthermore, by virtue of the fact that the or each tubular casing extends alongside the sleeve, access to the or a tubular lamp can be effected without disturbing the ballast or control gear for emergency use, or vice versa.

The invention is further illustrated by a description, by way of example of two preferred forms of electric lighting fitting and of two alternative forms of electric lighting fitting with reference to the accompanying drawings, in which: Figures 1 and 2, respectively, are perspective views of the first and second preferred forms of electric lighting fitting; Figure 3 is a perspective view of one alternative form of electric lighting fitting, and Figure 4 is a fragmental perspective view of a modified form of the alternative form of electric lighting fitting shown in Figure 3.

Referring to Figure 1, the preferred electric lighting fitting comprises an extruded sleeve 1 of transparent or translucent plastics material which contains at each of its ends a holder (not shown) for a fluorescent tube. An extruded tubular casing 2 of electrically insulating plastics material of shorter length than the sleeve 1 extends alongside the sleeve intermediate its ends and houses equipment (not shown) associated with the lighting fitting. At each of its ends, the sleeve 1 has a flange 3 of moulded plastics material and is closed by a separately formed end wall 5 of moulded plastics material. The tubular casing 2 at each of its ends has a flange 4 of moulded plastics material and is closed by a separately formed end wall 6 of moulded plastics material. The inner face of each end wall 5 and 6 has a peripherally continuous sealing ring (not shown) which effects a substantially fluid-tight seal with the flange 3 and 4. Extending between the sleeve 1 and the tubular casing 2 throughout the length of the sleeve is an elongate member 7 of sheet steel, the surface of the member nearer the sleeve constituting a light reflecting surface. The outer surface of the tubular casing 2 remote from the sleeve 1 and/or the surface of the elongate member 7 remote from the sleeve may have at least one longitudinally extending strengthening rib (not shown) which can also serve as a means to which can be secured separately formed components for mounting the lighting fitting on a ceiling, wall or other surface.

The second preferred form of lighting fitting shown in Figure 2 comprises an extruded sleeve 11 of transparent or translucent plastics material which contains at each of its ends a holder (not shown) for a fluorescent tube. An extruded tubular casing 12 of electrically insulating plastics material extends alongside the sleeve 11 over the whole of the length of the sleeve and houses equipment (not shown) associated with the lighting fitting. At each of its ends, the sleeve 11 has a flange 13 of moulded plastics material and at each of its ends the tubular casing 12 has a flange 14 of moulded plastics material.At each end of the lighting fitting, the adjacent open ends of the sleeve 11 and tubular housing 12 are closed by a single separately formed end wall 16 of moulded electrically insulating plastics material, the inner face of the end wall being provided with a peripherally continuous sealing ring (not shown) for effecting a substantially fluid-tight seal with the flanges 13 and 14. The outer surface of the tubular casing 12 remote from the elongate surface of light reflecting material may have at least one external longitudinally extending strengthening rib (not Shown). The tubular housing 12 may also contain control gear for emergency use. The surface of the tubular casing 12 nearer the sleeve 11 throughout its length carries a coating (not shown) of a light reflecting material.

The alternative form of lighting fitting shown in Figure 3 comprises an extruded sleeve 21 of transparent or translucent plastics material which contains at each of its ends a holder (not shown) for a fluorescent tube.

At each of its ends, the sleeve 21 has a flange 23 of moulded plastics material. Secured to one surface of the sleeve 21 tube is a separately formed extruded elongate member 27 of either plastics material or aluminium which, on its face immediately adjacent the sleeve has a coating (not shown) of light reflecting material and which, on its face remote from the sleeve, has two transversely spaced longitudinally extending strengthening ribs 28. At each end of the sleeve 11 is a separately formed extruded tubular casing 12 of electrically insulating plastics material which extends alongside the sleeve over a part of its length near one end of the sleeve and which inter-engages with the ribs 28 of the elongate member 29.Each tubular casing 22 is closed at the end of the casing remote from the neighbouring end of the sleeve 21 by an integral end wall 25; the other end of the casing is immediately adjacent the open end of the sleeve and the adjacent open end of the sleeve and of the casing are closed by a single end wall 26 which has on its inner surface a peripherally continuous sealing ring (not shown) for effecting a fluid-tight seal. One of the tubular casings 22 may contain equipment associated with the lighting fitting and the other tubular casing may contain control gear for emergency use. The exposed parts of the ribs 28 of the elongate member 27 extending between the tubular casings 22 will serve as a means to which can be secured separately formed components for mounting the lighting fitting on a ceiling, wall or other surface.

In the modified form of the alternative form of lighting fitting shown in Figure 4, the tubular casing 22 containing control gear for emergency use is omitted and the open end of the sleeve 31 having around its periphery a flange 33 of moulded plastics material is closed by a separately formed end wall 36 of moulded plastics material. In all other respects, the lighting fitting shown in Figure 4 is identical to that shown in Figure 3.

Claims

CLAIMS:

1. An electric lighting fitting for an elongate tubular lamp comprising a sleeve of transparent or translucent material which contains at least one holder for an elongate tubular lamp and which is closed at each of its ends by an end wall which is separately formed with respect to and is detachable from the sleeve; a tubular casing of electrically insulating material which extends alongside the sleeve over at least a part of the length of the sleeve and houses ballast associated with the lighting fitting, the tubular casing being closed at each of its ends by an end wall, at least one of which end walls is separately formed with respect to and is detachable from the tubular casing; and, extending between the sleeve and the tubular casing throughout substantially the whole of the length of the sleeve, an elongate surface of a light reflecting material.

2. An electric lighting fitting as claimed in Claim 1, wherein the tubular casing of electrically insulating material is of substantially the same length as the sleeve of transparent or translucent material.

3. An electric lighting fitting as claimed in Claim 2, wherein the tubular casing of electrically insulating material also houses control gear for emergency use.

4. An electric lighting fitting as claimed in Claim 1, wherein the tubular casing extends only over a part of the length of the sleeve and is positioned intermediate the ends of the sleeve.

5 An electric lighting fitting as claimed in Claim 1, wherein the tubular casing extends only over a part of the length of the sleeve and is positioned near one end of the sleeve with the adjacent end walls of the sleeve and casing lying alongside one another.

6. An electric lighting fitting as claimed in Claim 5, wherein a second tubular casing of electrically insulating material extends alongside, and over a part of the length of, the sleeve near the other end of the sleeve, the second casing housing control gear for emergency use.

7. An electric lighting fitting as claimed in Claim 5 or 6, wherein one or each of the end walls of the sleeve is integral with the adjacent end wall of the tubular casing or one of the tubular casings or is integral with a side wall of the tubular casing or one of the tubular casings.

8. An electric lighting fitting as claimed in any one of the preceding Claims, wherein both end walls of the or each tubular casing are separately formed with respect to and are readily detachable from the casing.

9. An electric lighting fitting as claimed in any one of the preceding Claims, wherein, where an end wall is separately formed with respect to the associated sleeve or tubular casing, a peripherally continuous fluid-tight sealing ring is provided between the sleeve or tubular casing and the end wall.

10. An electric lighting fitting as claimed in any one of the preceding Claims, wherein the elongate surface of a light reflecting material extending throughout substantially the whole of the length of the sleeve between the sleeve and the tubular casing or tubular casings is a surface nearer the sleeve of an elongate member which.is separately formed with respect to the sleeve and tubular casing or casings.

11. An electric lighting fitting as claimed in Claim 10, wherein the elongate member has on its surface remote from the sleeve one or more than one longitudinally extending strengthening rib which also serves as a means with which a part of the or each tubular casing engages.

12. An electric lighting fitting as claimed in any one of Claims 1 to 3, wherein the elongate surface of a light reflecting material is carried by the tubular casing.

13. An electric lighting fitting as claimed in any one of the preceding Claims, wherein the or each tubular casing has throughout at least a part of its length at least one internal longitudinally extending strengthening rib along which can be slidably engaged a support plate on which the ballast and/or control gear for emergency use can be mounted.

14. An electric lighting fitting as claimed in any one of the preceding Claims, wherein the or each tubular casing has on the side wall of the casing remote from the sleeve at least one external longitudinally extending strengthening rib which serves as a means to which can be secured separately formed components for mounting the lighting fitting on a ceiling, wall or other surface.

15. An electric lighting fitting as claimed in any one of the preceding Claims, wherein the sleeve for housing the or each tubular lamp is of extruded transparent or translucent plastics material.

16. An electric lighting fitting as claimed in any one of Claims 1 to 5 in which the end walls of the or each tubular casing are separately formed with respect to the casing, wherein the tubular casing is of an extruded electrically insulating plastics material.

17. An 'electric lighting fitting substantially as hereinbefore described with reference to and as shown in Figure 1 or 2 of the accompanying drawings.

18. An electric lighting fitting substantially as hereinbefore described with reference to and as shown in Figure 3 or 4 of the accompanying drawings.