GB2187037A

GB2187037A - Light tube protector

Info

Publication number: GB2187037A
Application number: GB08703329A
Authority: GB
Inventors: Robert Alexander Mclauchlan
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-02-19
Filing date: 1987-02-13
Publication date: 1987-08-26
Also published as: GB8703329D0; EP0238200A3; EP0238200A2; GB8604117D0

Abstract

A protector for a light tube, particularly an ultra violet sun bed lamp or fluorescent lighting tube is made of a flexible plastics material such as PVC, acrylic or polyethylene and encloses the tube, making contact with it at least at spaced positions, so as to contain any glass fragments if the tube should shatter. Several embodiments are described including the use of a loose polyethylene sleeve (10) retained by clips (13) Fig.1 (not shown) or an extruded acrylic tube (14) Figs. 2 and 3 having internal ribs (15) providing partial spacing from the surface of the light tube (11), the acrylic sheath being extruded over sized and shrunk onto the light tube by the application of heat. Alternatively, a flexible PVC sleeve (16) is expanded by compressed air, the light tube (11) inserted, and the sleeve then returning to its normal size. In a further alternative, a self-shrinking material such as cellulose is used in extruded form, soaked in water to expand it onto the light tube and dried to shrink onto the surface of the tube. The sheath may alternatively be in the form of a mesh. <IMAGE>

Description

GB 2 187 037 A SPECIFICATION separate spacers. Alternatively, the sheet

may be apertured to def ine a network of contact points.

Light tube protector The plastics material may be polyvinyl chloride (PVC), acrylic, cellulose or polyethylene.

This invention relatesto a lighttube protector. 70 The plastics material may betinted to provide The expression "lighttube" is intended to cover all colouring effects or may include pigments adapted types of fluorescent light source in which a glass to absorb particular parts of the spectrum emitted by envelope of tubularform encloses a low-pressure the lighttube.

gas,through which an electric discharge is Partial transparencies may be inserted between maintained to emit lightwhich may be in thevisible 75 the sheet and the tube carrying indicia such as or ultraviolet spectral range. instructions for use, advertising material or a name The invention is concerned with relatively low ortrade mark.

power light tubes, typically of lessthan 200Watts, The plastics material itself may also be printed ratherthan high power industrial process light priorto being applied tothe lighttube.

sourceswhich emit considerable heat. The invention 80 The invention maytake a numberof formswhich was primarily devised for usewith ultra violet light will now be described in more detail byway of sources used in sun beds and solaria. However, it example onlywith reference to the accompanying may equally be applicable to conventional drawings in which fluorescent lighting tubes. Figure 1 is a perspective view of a lighttube having Lighttubes may be of substantial lengthJor 85 afirstform of protector.

example 1.8 metres long, and have a tubular glass Figure2 is a similar perspectiveview of a lighttube envelope containing a suitable gas at below having a second form of protector.

atmospheric pressure. If a tube is damaged it may Figure 3 is a section on the line 3-3 of Figure 3.

collapse inwardly or "implode", scattering slivers of Figure 4i11ustrates a stage in inserting a lighttube glass with considerable force. 90 into a furtherform of protector.

Lighttubes are carefully manufactured to high Figure 5is a further embodiment of protector.

standards so that shattering of the tube is a rare Referring firstlyto Figure 1, a simple form of light occurrence but nevertheless it can happen and is tube protector is illustrated. In this simple form a particularly hazardous in some circumstances. For loose tubular sheath 10 of polyethylene film is example, in sun beds, the tubes may be only a short 95 provided. A lighttube 11 is inserted within the distance away from the userwho would be polyethlene sheath 10 so that only the end caps 12 of unprotected if one of the tubes were to shatter in use. the tube project. The lighttube is then used in the In a factory, moving parts may approach lighting normal manner.

unitswith a risk of thetubes being struckand If the lighttube is broken in use orduring handling, damaged. 100 particles of glass are eithercontained bythe sleeve It is an object of the present invention to provide a or, if the sleeve itself is damaged, their scattering protectorfor lighttubes which overcomes or reduces range and velocity are reduced.

the possibility of injury or glass contamination if a The loose polyethylene sleeve may be secured in lighttube shatters in use or during handling. place atthe ends of the tube, for example by According to the invention there is provided a light 105 adhesive on thetube, adhesive tape applied tube protector comprising a sheath of flexible externally, or by being tied in position by an external transparent ortranslucent sheet-like plastics tie. External circlips or internally-disposed material which is adapted to contact a lighttube and expanding fixing rings may also be used for securing at least partly to enclose it. the sleeve to the tube, the latter also serving as It is known to use a rigid plastics diffuser on a light 110 spacers.

tube and to provide a rigid transparent acrylic cover In this example shown in Figure 1, external circlips plate on a sunbed overlying the ultraviolet 13 are used to securethe sleeve 10 to the tube 11.

generating tubes. This type of rigid covering, Figures 2 and 3 of the drawings illustrate an separated from the light tubes themselves does not alternative form of light tube protector. In this form part of the present invention. 115 second version a PVC sleeve 14, which may be an Preferably, the sheath of plastics material is extrusion, is placed overthe lighttube and heat is tubular. applied either externally, or bythe tube itself being Alternatively the sheath may be in the form of a flat operated,which causes the PVC sleeve 14to shrink sheet adapted to be wrapped around thetube and onto the surface of the tube 11. This sleeve 14 secured. As a further alternative, the sheath may be 120 contacts the surface of the tube so that, in effectthe deposited directlyfrom molten plastics material or a PVC is laminated onto thetube.

solution of a plastics material. Spacers in the form of internal ribs orformations The surface of the sheath may have continuous 15 can be provided in the sleeve 14, during extrusion.

contact with the light tube. Alternatively, it may Where such spacers are provided, contact is made contactthe light tube at regularly spaced positions or 125 between the PVC extrusion and the lighttube butthe may loosely surround the lighttube and make rest of the extrusion is slightly spaced from the light contact at random positions. tube. This reduces the tendency for f u rther shrinkage Contact at spaced positions can be achieved by of the extrusion when the lighttube is used and its providing surface ridges or otherformations onthe surface becomes warm.

inner surface of the sheath of plastics material, or by 130 The spacers also a] low ventilation of the tube.

2 GB 2 187 037 A 2 Figure 4 of the drawings illustrates an alternative lifeto beexpectedfrom it because the plastics form of protector being placed onto a lighttube. In material only contactsthetube atthe position of the this example, a tubular polyvinyl chloride skin 16 is spacers.

expanded,with compressed air introduced atthe It is not necessaryforthe spacersto be initially end 17 of thesleevefor example, and the lighttube 70 integral with the plastics sleeve. Separate spacers 11 is fed into the expanded PVC sleeve 16. The air may be put on the lighttube before the plastics pressure is released so thatthe PVC skin is restored material is added. For example, these may comprise to its normal unexpanded size and contacts the light rings or a spiral of plastics or metal mounted on the tube. tube.

In a fourth example (not illustrated) a semi-flexible 75 The invention is not suitable for application to high extruded acrylic sleeve is slid onto the tube. It may be powered tubes which generate very large quantities a close sliding fit or may have integral internal of heat, such as those used in applying ultra-violet spacers formed during extrusion. light in industrial processes. In this case, it is Figure 5 of the drawings illustrates an alternative frequently necessaryto provide waterjackets and semi-flexible acrylic sleeve which is provided with 80 similar assisted cooling forthe lighttube. The type of perforations. The sheet 18 thereforetakes on the protector envisaged bythe present invention is not characteristics of a "net" which will serve to contain appropriate in these cases and is intended onlyfor a shattering lighttube without entirely enclosing it. use with lighttubes of relatively low power,typically Where a perforated plastics material is used,there is lessthan 200 Watts, reaching no more than 120 unlikelyto be significant absorption of lightfrom the 85 Celsius.

tube. However, in some circumstances it may In conventional ultra violet sun bed tubes and actually be desirableforthe characteristics of the fluorescent lighting tubes it has been found lightto be altered bythe plastics material,for experimentally that, although the surface of the exampleto give a warmertintto fluorescent light or glass envelope of the lighttube becomeswarm in to absorb some partof the spectrum of an ultraviolet 90 use, itstemperature is sufficiently lowto prevent emitter. In this case, no perforations would be rapid deterioration of the surrounding plastics provided in the plastics material. protector. Thus, surprisingly, a fluorescent lighttube In a further embodiment, not shown in the or ultraviolet lamp can be protected bythe means drawings,the sheath is made of a self-shrinking described above without overheating. Direct contact material such as cellulose. This has the property of 95 between the plastics sheet and thetube in particular expanding by absorption when soaked in water, avoids entrapment of an air insulating layer.

returning to its normal size on drying. A protectorof ltwill be appreciated thatthe invention is not such a self-shrinking material has the advantage that limited to lightfitments in the form of straighttubes it can be supplied forfitmentto existing tubes bythe but also covers curved, coiled or circular fluorescent end user, orto a distributor orwarehouse outletfor 100 lamps of generally known type and coloured display fitmentto standard lighttubes, ratherthan being tubes of neon and similartypes.

applied to the tubes bythe manufacturer. Cellulose While it is convenient forthe plastics material to be can also be printed in one orfull colourwith in a tubularform, a similar effect may be achieved instructions ora trade mark picture or pattern for using a laminar sheet which iswrapped roundthe example. 105 lightsource and secured in position byadhesive, by Where a sheath of another material such as PVC is adhesivetapeor mechanically bytying orclipping.

used,there may besome advantage in using Thefilm may be of an adhesive type which will self-shrinking tubular end caps of cellulosefor adhere directlyto the tube orof a self-adhering type.

instance, to secure the sheath to the light tube which can be secured in position by overlapping the without other f ixi ng. In particularrthis servesto 110 edges of the sheet about the lighttube.

coveranygap between the sheath andtheend caps. As a further alternative, the lighttube can be Such a gap mightexistusing some plastics materials dipped in a molten plastics material or a solution of a which are excellentforthe transmission of ultra plastics material in a suitable fast evaporating violet light butwhich may notwithstand the solvent.

increased temperature occurring at each end of the 115

Claims

lighttube in use. The gap may also be closed by a CLAIMS metal or ceramic

cylinder section which may be moulded or extruded to connectthe circular metal 1. A lighttube protector comprising a sheath of terminal fitting of the lighttubeto the plastics flexible transparent ortranslucent sheet-like plastics material. This must be done in such away that if the 120 material which is adapted to contact the light tube lighttube is broken, the glass remains contained. and at least partly to enclose it.

The glass envelope of the light tube tends to
2. A protector according to Claim 1 wherein the become warm in use and it is therefore necessary to sheath of plastics material istubular.

selectthe plastics material and thetype of
3. A protector according to Claim 1 or Claim 2 construction carefully so that the protection afforded 125 wherein the surface of the sheath has continuous bythe plastics is retained throughoutthe life of the contactwiththe lighttube.

tube. In particular, grades of plastics having
4. A protector according to Claim 1 or Claim 2 resistance to ultraviolet degradation are to be wherein the sheath contacts the light tube at preferred. The use of spacers in the form of ribs or regularlyspaced positions.

wrinkles inside the plastics material can extend the 130
5.A protector according to Claim 1 or Claim 2 3 GB 2 187 037 A 3 wherein the sheath loosely surrounds the lighttube 27. A lighttube having a protector substantially and makes contact at random positions. as herein before described with reference to and as
6. A protector according to Claim 4 wherein illustrated in Figure 5 of the drawings.

contact is provided at spaced positions by surface ridges or other formations on the inner surface of the plastics material sheath.
7. A protector according to Claim 4wherein Printed for Her Majesty's Stationery Office by Croydon Printing Company (UK) Ltd,7187, D8991685.

contact is provided at spaced positions by spacers Published byThe Patent Office, 25 Southampton Buildings, London,WC2A lAY, initially separate from the plastics material sheath. from which copies maybe obtained.
8. A protector according to claim 4 wherein the sheath is apertured to define a network of contact points atwhich it is adapted to contact the tube.
9. A protector according to any preceding claim and made of polyvinyl chloride (PVC).
10. A protector according to anyone of Claims 1 to 8 and made of acrylic plastics material.
11. A protector according to anyone of Claims 1 to 8 and made of polyethylene.
12. A protector according to anyone of Claims 1 to 8 and made of cellulose.
13. A protector according to any preceding claim wherein the plastics material is tinted to provide colouring effects.
14. A protector according to anyone of Claims 1 to 12 wherein the plastics material includes pigments adapted to absorb particular parts of the spectrum emitted by the light tube forwhich it is intended.
15. A protector according to anyone of Claims 1 to 12 wherein the plastics material is printed.
16. Alight tube having a protector according to anyone of Claims 1 to 15.
17. Alighttube according to Claim 16 and comprising an ultraviolet sun lamp tube.
18. Alight tube according to Claim 16 and comprising a fluorescent lighttube emitting visible light.
19. A lighttube according to anyone of Claims 16 to 18wherein partial transparencies are inserted between the sheath and the lighttube carrying indicia.
20. A light tube protector substantially as herein before described with reference to and as illustrated in Figure 1 of the accompanying drawings.
21. A lighttube protector substantially as hereinbefore described with reference to and as illustrated in Figures 2 and 3 of the accompanying drawings.
22. Alight tube protector substantially as hereinbefore described with reference to and as illustrated in Figure 4 of the drawings.
23. A lighttube protector substantially as hereinbefore described with reference to and as illustrated in Figure 5 of the drawings.
24. Alight tube having a protector substantially as hereinbefore described with reference to and as illustrated in Figure 1 of the accompanying drawings.
25. A lighttube having a protector substantially as hereinbef ore described with reference to and as illustrated in Figures 2 and 3 of the drawings.
26. A lighttube having a protector substantially as hereinbefore described with reference to and as illustrated in Figure 4 of the drawings.