GB2310078A

GB2310078A - Discharge lamps

Info

Publication number: GB2310078A
Application number: GB9701120A
Authority: GB
Inventors: Terence Milner; Paul England
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-01-24
Filing date: 1997-01-20
Publication date: 1997-08-13
Anticipated expiration: 2017-01-20
Also published as: WO1997027616A1; GB9701120D0; GB2310078B; AU1395497A; GB9601418D0

Abstract

Fluorescent discharge tubes 2,5 are connected at opposed ends to a lamp housing 8. The ends 3 and 4 or 6 and 7 of each tube are offset from each other in order to provide support to prevent the tubes from tending to sag downwardly. Each tube has a straight section 10 that is spaced from the housing to allow the lamp to be handled without touching the tube by gripping the housing. Each tube may have its own control circuit to allow one tube to work in the event of failure of the circuit for the other tube.

Description

LIGHTING DEVICE The present invention relates to a lighting device of the discharge lamp type, and particularly to a discharge lamp having a plurality of discharge tubes.

A lamp for general lighting application, comprising a single fluorescent discharge tube and a central housing is known in European patent application EP 0,057,974B.

The fluorescent discharge tube of the known lamp has first and second ends on one side of a central housing. The tube extends in a substantially rectangular loop around the outside of the housing, and occupies a substantially rectangular area, and is supported by a plurality of arms extending from the housing and connecting to a straight length of the tube farthest from the ends.

Specific embodiments of the present invention aim to provide a substantially flat discharge tube lamp package, making efficient use of the available space to provide a high light output whilst enabling efficient dissipation of generated heat.

Further, specific embodiments of the present invention aim to provide a discharge tube lamp package which is easily handled without the need to touch the discharge tube.

According to one aspect of the present invention there is provided a lamp comprising a light emitting tube connected at each end to a housing characterised in that the tube undergoes a change in direction along its length whereby the longitudinal extent of the tube at one end in a direction away from the tube at that end is at an angle other than zero to the longitudinal extent of the tube of the other end in a direction away from the tube at that end.

The extent at one end may extend towards the extent at the other end.

The angle may be more than 90" and may be approximately 1800.

The longitudinal extent of the tube at each end may be offset from each other for instance in a vertical direction or in a horizontal direction or both.

Each end of the tube may be received in a different side of the housing.

The tube may include an intermediate section that is spaced from the housing which may be substantially straight. A first curved portion may be provided between a first end of the tube and the intermediate section and a second curved portion may be provided between the intermediate section and the second end of the tube. At least one of the first and second ends of the tube may extend substantially parallel to the main lengthSof the intermediate section. The first and second ends of the tube may be spaced apart from the intermediate section.

At least one of the first or second curved portions may have an internal radius of curvature greater than or equal to the thickness of the tube. The second curved portion may have an internal radius of curvature greater than an internal radius of curvature of the first curved portion.

One of the curved portions may be substantially semi toroidal. One of the curved portion may be substantially U shaped.

The tube may be supported by the housing solely at its end regions.

A further light emitting tube may be provided, said further tube having any of the features of the first mentioned tube referred to above. Each of the tubes may have a first end and a second end, at least one of the first or second ends of the tubes being parallel to each other. Both tubes may have an intermediate portion spaced from the housing at opposed sides of the housing. The tubes may have separate circuits. The separate circuits may allow one tube to continue to emit light in the event of failure of circuit for the other tube or alternatively or additionally, may allow one of the tubes to be able to be switched on to emit light in the event of the failure of the circuit for the other tube. A portion of the tubes may coincide with a quadrilateral.

The generally longitudinal extent of the or each tube may extend in a direction transverse to the vertical. The generally longitudinal extent of the or each tube may be substantially horizontal.

According to a further aspect of the present invention, a light emitting tube is characterised in that the tube undergoes a change in direction along the length whereby the longitudinal extent of the tube at one end in a direction away from the tube at the end is at an angle other than zero to the longitudinal extent of the tube at the other end in a direction away from the tube.

The extent at one end of the tube may extend towards the extent at the other end. The angle may be more than 900 and may be approximately 180 .

The longitudinal extent of the tube at each end may be offset from each other.

Each end region may extend alongside an intermediate region of a tube.

Each end region may be spaced from the intermediate region.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which: Figure 1 shows in plan view a lamp according to a first specific embodiment of the present invention; and Figure 2 shows schematically a central housing of the lamp of figure 1.

Referring to figure 1 of the accompanying drawings, a lamp 1 comprises a first fluorescent discharge tube 2 having respective first and second ends 3, 4, a second fluorescent discharge tube 5 having respective first and second ends 6, 7 and a central housing 8, supporting the first and second discharge tubes.

Each discharge tube comprises an elongate portion 10 spaced apart from the first and second ends. At the first end, is provided a respective first terminal 11, and at the second end a respective second terminal 12. Between the first end and the elongate portion is provided, a first curved portion 13 of a substantially semi toroidal shape, and between the second end and the elongate portion is a second curved portion 14 of a substantially "U" shape.

The first and second tubes may be substantially mirror images of each other.

The first and second tubes are arranged connected to the housing such that the first ends are held at one side of the housing, and the second ends are held at another, opposite side of the housing 8.

Due to the first and second ends of each tube being held by the housing 8 at positions spaced apart from each other, the tube ends are rigidly held by the housing, the tubes each extending in a loop external of the housing between the respective first and second ends.

The elongate straight portions 10 are each spaced apart from the central housing 8 with a clearly defined aperture area 20 therebetween, the aperture 20 being enclosed by each tube which forms a loop between the first and second ends.

The areas 20 are sufficient large to enable grasping of the housing 8 without needing to touch the first or second tubes.

The first and second ends are supported in the central housing 8, entering the central housing on opposite sides of the housing to each other.

The first and second ends 3, 4 or 6, 7 are spaced apart from each other and for each tube, the first end faces in a direction opposite to a direction in which the second end faces.

Figure 1 shows the lamp in plan view.

In plan view, an outer perimeter of the first and second tubes coincide substantially with a quadrilateral ABCD as shown dotted in figure 1, the lamp being contained within the area described by the quadrilateral ABCD when viewed in plan view.

In the plan view of figure 1, the first and second ends of each tube are offset from each other such that a line continuing from the extent of one end 3 will not be coincident with the centre of the other end. That distance of offset may be approximately one tube thickness or less.

In side elevation, the first and second tubes may be substantially flat, or the first end may be vertically offset with respect to the second end, by a distance of the order of one or two tube thicknesses.

The offset of the ends of the tube, either in plan view or in side view or both, may assist in retaining the tube in position as the offset allows the mountings of the ends of the tubes to more readily resist any . forces tending to cause the tube to swing the elongate portion 10 downwardly than would be the case if the ends were coincident.

Referring to figure 2 of the accompanying drawings, there is shown in further detail the central housing 8 and the first terminal 11 of the first tube, the first terminal 16 of the second tube, the second terminal 12 of the first tube and the second terminal 17 of the second tube, supported by the housing. The housing comprises a plastics moulding having a first set of connectors 20, 21 for receiving the first terminals and a second set of connectors 22, 23 for receiving the second terminals.

First and second starter circuits 24, 25 are provided within the housing. The central housing resides substantially centrally of the quadrilateral ABCD. The first and second tubes are deployed one to either side of the central housing on opposite sides of the housing such as to be substantially symmetrical when viewed in plan view.

Either or both terminals of each tube may move in a relative vertical direction to the housing in order to connect the tube to the connectors of the housing. In this instance the housing may include a cover which can be attached after the tubes have been reconnected.

Alternatively or additionally one or both connectors of the housing for each tube may be reciprocatable in the housing such that one end of the tube can be engaged with a connector of the housing with that end of the tube and the connector being moved into the housing to allow the other end of the tube to be engaged with the other connector of the housing. Either or both of the connectors of the housing may be arranged to urge the connector in a direction away from the housing when the connector is pushed in a direction into the housing. That urging may be provided by spring means.

The circuitry of the housing is such that, if one tube fails, or its associated circuitry fails then the other tube will remain illuminated. Furthermore, if one tube or its circuit has failed and the light has been switched off, when the unit is switched on again the working light will illuminate. Accordingly the unit has a fail safe feature which allows light to be emitted, albeit at a reduced level, should there be a failure in the unit. This feature is particularly useful in emergency lighting applications.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A lamp comprising a light emitting tube connected at each end to a housing characterised in that the tube undergoes a change in direction along its length whereby the longitudinal extent of the tube at one end in a direction away from the tube at that end is at an angle other than zero to the longitudinal extent of the tube of the other end in a direction away from the tube at that end.

2. A lamp as claimed in claim 1 in which the extent at one end extends towards the extent at the other end.

3. A lamp as claimed in claim 1 or 2 in which the angle is more than 900.

4. A lamp as claimed in claim 3 in which the angle is approximately 1800.

5. A lamp as claimed in any preceding claim in which the longitudinal extent of the tube at each end are offset from each other.

6. A lamp as claimed in claim 5 in which the offset is in a vertical direction.

7. A lamp as claimed in claim 5 or 6 in which the offset is in a horizontal direction.

8. A lamp as claimed in any preceding claim in which each end of the tube is received in a different side of the housing.

9. A lamp as claimed in any preceding claim in which the tube includes an intermediate section that is spaced from the housing.

10. A lamp as claimed in claim 9 in which the intermediate section is substantially straight.

11. A lamp as claimed in claim 10 in which there is a first curved portion between a first end of the tube and the intermediate section and a second curved portion between the intermediate section and the second end of the tube.

12. A lamp as claimed in claim 11 in which at least one of the first and second ends of the tube extend substantially parallel to the main length of the intermediate section.

13. A lamp as claimed in either of claims 11 or 12 in which the first and second ends of the tube are spaced apart from the intermediate section.

14. A lamp as claimed in Claim 11 to 13 in which at least one of the first or second curved portions has an ipternal radius of curvature greater than or equal to the thickness of the tube.

15. A lamp as claimed in any of claims 11 to 14 in which the second curved portion has an internal radius of curvature greater than an internal radius of curvature of the first curved portion.

16. A lamp as claimed in any of claims 11 to 15 in which one of the curved portions is substantially semi toroidal.

17. A lamp as claimed in any of claims 11 to 16 in which one of the curved portions is substantially "U" shaped.

18. A lamp as claimed in any preceding claim in which the tube is supported by the housing solely at its end regions.

19. A lamp as claimed in any preceding claim including a further light emitting tube, said further tube having any of the features of the first mentioned tube.

20. A lamp as claimed in claim 19 in which each of the tubes has a first end and a second end, at least one of the first or second ends of the tubes being parallel to each other.

21. A lamp as claimed in claim 19 or 20 in which both tubes have an intermediate portion spaced from the housing at opposed sides of the housing.

22. A lamp as claimed in any preceding claim in which the tubes have separate circuits.

23. A lamp as claimed in claim 22 in which the separate circuits allow one tube to continue to emit light in the event of failure of circuit for the other tube.

24. A lamp as claimed in claim 22 or 23 in which the separate circuits allow one of the tubes to be able to be switched on to emit light in the event of the failure of the circuit for the other tube.

25. A lamp as claimed in any of claims 19 to 24 in which a portion of the tube coincides with a quadrilateral.

26. A lamp as claimed in any preceding claim in which the generally longitudinal extend of the or each tube extends in a direction transverse to the vertical.

27. A lamp as claimed in claim 26 in which the generally longitudinal extent of the or each tube extends substantially horizontally.

28. A lamp substantially as herein described with reference to, and as shown in figures 1 and 2 of the accompanying drawings.

29. A light emitting tube characterised in that the tube undergoes a change in direction along the length whereby the longitudinal extent of the tube at one end in a direction away from the tube at that end is at an angle other than zero to the longitudinal extent of the tube at the other end in a direction away from the tube.

30. A tube as claimed in claim 29 in which the extent at one end extends towards the extent at the other end.

31. A tube as claimed in claim 29 or 30 in which the angle is greater than 900.

32. A tube as claimed in claim 31 in which the angle is approximately 1800.

33. A lamp as claimed in any of claims 29 to 32 in which the longitudinal extent of the tube at each end is offset from each other.

34. A lamp as claimed in any of claims 29 to 33 in which each end of the tube extends alongside an intermediate region of a tube.

35. A tube as claimed in any of claims 29 to 34 in which each end region is spaced from the intermediate region.

36. A light emitting tube substantially as herein described with reference to, and as shown in figures 1 and 2 of the accompanying drawings.