GB2480243A

GB2480243A - A shroud

Info

Publication number: GB2480243A
Application number: GB201007750A
Authority: GB
Inventors: David Charles Payne
Original assignee: FOTOLEC TECHNOLOGIES Ltd
Current assignee: FOTOLEC TECHNOLOGIES Ltd
Priority date: 2010-05-10
Filing date: 2010-05-10
Publication date: 2011-11-16
Anticipated expiration: 2030-05-10
Also published as: GB2480243B; EP2569797A2; WO2011141732A2; GB201007750D0; WO2011141732A3

Abstract

A shroud 22 to shroud a metallic end cap 23 of a fragment retention lamp, for example, a fluorescent tube 20 with a protective cover 21. The shroud 22 covers the sides and end face of the end cap 23. Orifices 26, 27 in the shroud 22 allow electrical contact pins 24,25 to protrude through the shroud 22. The shroud 22 may be formed from a film coating process or as a separate preformed structure. The shroud may be formed on the end cap 23 before or after the protective cover 21 (31, fig 4) is formed on the lamp 20.

Description

A SHROUD

Field of the Invention

The invention relates to shrouds for use with electrical lamps and in particular to fragment retention lamps.

Background of the Invention

The closest prior art is the applicant's own process of coating fluorescent tubes with a plastics film, so that if the tube shatters in use, the plastics film retains all of the glass fragments.

There are two methods of film coating lamps for this purpose. The first method is to form a plastic tube, which is fitted closely over the lamp and then subsequently heat-shrink the tube around the lamp. The second method is the Applicant's own method of feeding an uncoated lamp through a crosshead extrusion, which progressively coats the lamp along its length. The coating of the lamp is subsequently cooled as the lamp emerges from the cone of molten material.

Problem to be Solved The problem/main disadvantage of the fragment retention lamp is that it is a statutory requirement that a representative sample of one of these coated tubes, after coating, should survive a so-called "drop test". In this test, the coated tube is held horizontally and then dropped from a distance of approximately four metres. On impact, the tube fractures and no sliver of glass must escape the tube, otherwise the tube fails the test.

If in practice the tube hits the ground at an angle, i.e. wherein the periphery of its own soft aluminium end cap becomes dented, it then becomes possible for a fragment of glass to escape the tube through the dent-formed gap between the cap and the plastics-film coating.

The invention, by coating the end cap with a suitable plastics material, will contain the glass on impact and therefore seeks to solve this problem.

Brief Description of the Figures

Figure 1 shows a schematic side view of a fragment retention lamp incorporating a damaged end cap.

Figure 2 shows a schematic end view of a fragment retention lamp incorporating a damaged end cap.

Figure 3 shows a cross-sectional view of the fragment retention lamp incorporating a shroud cover, over a protective film layer and a metallic end cap.

Figure 4 shows a cross-sectional view of the fragment retention lamp incorporating a shroud, which encloses a metallic end cap, whereby the shroud is underneath a protective film layer.

Detailed Description of the Figures

Figure 1 shows an exaggerated part-elongate cross-section of a conventional fluorescent lamp, generally indicated by arrow 1, which is coated by a plastics film 2. The film coating 2 does not cover the electrical contact pins 4 and 5. The tube 1 incorporates a conventional metallic end cap 6, located at one end of the tube 1, which is typically manufactured from an aluminium material. The cap 6 incorporates an upper damaged portion 7, which has been dented inwards. The damaged portion 7 of the cap 6 allows glass fragments from the tube 1, to escape the plastics film coating 2 in the direction indicated by arrow 3.

Figure 2 shows an enlarged cross-sectional end view of the tube 1, which is identical to the tube shown in Figure 1. The tube 1 is substantially cylindrical in shape and incorporates a metallic end cap 6. The end cap 6 incorporates two electrical contact pins 4 and 5, which are axially arranged about the centre of the cap 6. The cap 6 incorporates an upper damaged portion 7, which has been dented inwards from the cap's outer peripheral edge.

Therefore, creating a gap 10 between the metallic end cap 6 and the plastics coating 2, which may allow glass fragments to escape the tube 1.

Figure 3 shows an enlarged elongate section showing a fluorescent lamp end portion, generally indicated by arrow 20, according to the invention.

The tube 20 incorporates a metallic end cap 23 located at one end. The tube 20 also incorporates a plastics coating 21, which is adjacent the outer surface of the tube 20. A shroud 22 is located over the end tube 20 and is attached to the plastics coating 21. The shroud 22 is typically formed from insulating plastics material, which may be in a mouldable, machinable form. Or alternatively, the shroud 22 may be formed from a coating of plastics material. The coating may be typically applied from a spray or dipping means. The shroud 22 is manufactured from a plastics material because it is incapable of short-circuiting the electrical contact pins 24 and 25 together and therefore eliminating any possibility of an electrical hazard. Furthermore, the plastics material is a lightweight material and will therefore not put any excessive mechanical loading on to the electrical contact pins 24 and 25 whist the tube is connected to a light fitting.

The shroud 22 is configured so that it provides a close fitting to both the outer surface of the fluorescent lamp 20 and the end face of the metallic end cap 23. The electrical contact pins 24 and 25 extend through two orifices 26 and 27 within the shroud 22, and subsequently protrude from the outer surface of the end cap by a predetermined amount.

The shroud 22 incorporates a portion, which extends over the outer wall of the end cap 23 and a portion of the tube 20. The shroud also incorporates a portion, which covers and abuts the end face portion of the metallic end cap 23, which facilitates in the protrusion of the electrical contact pins 24 and 25 from the outer surface of the shroud 22.

Figure 4 shows an enlarged elongate section showing a fluorescent lamp end portion, generally indicated by arrow 30, according to an alternative embodiment of the invention.

The tube 30 incorporates a metallic end cap 33 located at one end. The tube 30 incorporates a shroud 32 located over one end of the tube and is attached directly onto the outer surface of the fluorescent lamp 30. A plastics coating 31 is then applied to the outer surfaces of both the illumination tube 30 and the shroud 32. The shroud 32 is shown to extend along the outer wall of the end cap and onto a portion of the tube 30.

The shroud 32 also abuts the outer end surface of the end cap 33. The electrical contact pins 34 and 35 extend through two orifices 36 and 37 within the shroud 32 and are free from any plastics coating material.

The shroud may be in a form of a formed plastics shell cap and others, but it is important that the electrical pins project at least by a given minimum distance (set by statutory requirements) from the end face of whatever cap or caps adjoin them.

In an alternative embodiment of the invention, the inner surface of the shroud may incorporate a high friction inner surface, which enables the shroud to attach itself to the plastics coating by a friction fitting means. Or, alternatively, the shroud may incorporate an adhesive/sticky surface, which provides a means of bonding the shroud 22 to the lamp 20.

Claims

Claims 1. A shroud adapted, in use, to shroud a metallic end cap disposed at both ends ee eR4-of a fragment retention lamp, the device comprising a first body portion and a second body portion; wherein said first body portion covers in use an external wall of said end cap, and said second body portion in use covers an end face of said end cap and incorporates one or more orifices through which, in use, an electrical contact pin or pins can protrude from said shroud.
2. A shroud in accordance with claim 1, wherein said first body portion of said shroud further comprises an extended portion to cover, in use, a portion of the lamp body beyond the cap.
3. A shroud in accordance with either preceding claim, further comprising a friction fitting means for attaching said shroud to said lamp body.
4. A shroud in accordance with any of the preceding claims, wherein said second body portion of said shroud abuts the outer end surface of said end cap.
5. A shroud in accordance with any of the preceding claims, wherein said shroud is a preformed cap.
6. A shroud in accordance with any of the preceding claims, wherein said shroud is preformed from a plastics material.
7. A shroud in accordance with any of the preceding claims, wherein said shroud is formed from a coating of plastics material.
8. A shroud substantially for use with a fragment retention lamp as hereinbefore described and/or illustrated in any appropriate combination of the accompanying text and/or Figures.
9. A method of shrouding a metallic end cap of a fragment retention lamp, characterised in that the method comprises film-coating the or each said lamp end cap in a manner such as to shroud external wall and the end face of the or each said cap and surround the or each electrical contact pin of the cap whilst allowing said pin(s) to protrude by the necessary amount from said end face; in that the film-coating step, which forms the shroud when completed, is on operation distinct from the fragment retention film-coating of the lamp body itself and in that it takes place before or after the last said film-coating.
10. A method of shrouding the end cap of a fragment retention lamp, the method being carried out, substantially as described herein.
11. A fragment retention lamp incorporating a shroud in accordance with any of claims 1 to 7.
12. A fragment retention lamp with one or more of its end caps shrouded by a method carried out in accordance with claim 8 or claim 9.