WO2006093402A1

WO2006093402A1 - A lamp holder and a method for supporting and electrically contacting a tube lamp, an inner sleeve and an outer sleeve of the lamp holder, a lighting fixture provided with such a lamp holder and a tube lamp provided with an inner sleeve

Info

Publication number: WO2006093402A1
Application number: PCT/NL2006/000101
Authority: WO
Inventors: Peter Jacobus Maria Timmermans
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-03-01
Filing date: 2006-02-27
Publication date: 2006-09-08
Anticipated expiration: 2007-09-01
Also published as: NL1030707A1; NL1030707C2

Abstract

Lamp holder and method for supporting and electrically contacting a tube lamp (1) at a free end (3) thereof that is provided with an outwardly projecting, wirelike electrical contact element (4), which lamp holder is elongate in shape, comprising: a cylindrical inner sleeve (10; 50; 90) provided with a receiving opening for receiving a free end (3) of the tube lamp (1) therein, a cylindrical outer sleeve (20; 70; 120) provided with a receiving opening for receiving the inner sleeve (10; 50; 90) therein, and an electrical contact member provided with a receiving opening for receiving the wirelike contact element (4, 5) therein, wherein the receiving openings of the inner sleeve (10; 50; 90), the outer sleeve (20; 70; 120) and the contact member are aligned in the longitudinal direction of the lamp holder, in such a manner that the sleeves (10; 50; 90; 20; 70; 120) can rotate relative to each other about the longitudinal direction of the lamp holder in mounted condition so as to enable the contact member to electrically contact the wirelike electrical contact element (4, 5).

Description

A lamp holder and a method for supporting and electrically contacting a tube lamp, an inner sleeve and an outer sleeve of the lamp holder, a lighting fixture provided with such a lamp holder and a tube lamp provided with an inner sleeve.

DESCRIPTION

The invention relates to a lamp holder for supporting and electrically contacting a tube lamp at at least one free end thereof that is provided with an outwardly projecting, wirelike electrical contact element, which lamp holder is elongate in shape, comprising:

- an inner sleeve in the form of an essentially cylindrical body having a circumferential edge that defines a longitudinally extending receiving opening in the inner sleeve for receiving a free end of the tube lamp therein,

- an outer sleeve in the form of an essentially cylindrical body having a circumferential edge that defines a longitudinally extending receiving opening extending in the outer sleeve for receiving the inner sleeve therein, and

- an electrical contact member provided with a receiving opening for receiving the wirelike contact element therein, wherein the receiving openings of the inner sleeve, the outer sleeve and the contact member are aligned in the longitudinal direction of the lamp holder.

A lamp holder of this kind for electrically connecting tube lambs, such as the elongate fluorescent gas discharge lamps, generally referred to as TL

("Tube Light") tubes, which are known per se in practice, is known from US patent

No. 6,193,534 B1. At their end faces, TL tubes are provided with two or more wirelike contact elements in the form of robust contact pins projecting from the tube lamp in the longitudinal direction thereof.

With this known lamp holder, the electrical contact between the lamp and a contact wire extending from the lamp holder is effected by inserting the inner sleeve into the outer sleeve and each contact pin into a respective contact member in longitudinal direction.

Furthermore, lamp holders for TL tubes are known in practice in which the contact pins can be inserted into the lamp holder via a slot that is present therein. The contact pins are electrically contacted with an electrical contact member, generally in the form of two electrically conductive, spring lips that are mounted in the lamp holder, by turning the lamp about its longitudinal axis. Generally the tube lamp must be turned a quarter turn so that the contact pins are no longer positioned in front of the slots in the lamp holder so as to prevent the lamp from being undesirably detached from the lamp holder.

With these lamp holders that are known from practice, the force required for electrically contacting and supporting the tube lamp is fully transmitted to and taken up by the robust contact pins.

Recently Philips, among other companies, has marketed tube lambs such as the so-called "Double Ended High Frequency Currency Lamp" having a power of 1000 Watt, for example, from the ends of the glass tube body of which a single wirelike contact element of molybdenum having a relatively small diameter of about 1 - 1.5 mm projects. In another embodiment of this lamp, a flexible litzen wire is attached to the contact element for electrically connecting the lamp, for example by soldering. The use of litzen wire leads to an effective reduction of the current displacement effect, also referred to as "skinn effect", that occurs at high operating frequencies of the lamp (from 40 kHz to 100 kHz or higher).

Unlike the contact elements of the above-described known TL tubes, the relatively thin wirelike contact elements of these new tube lamps and also the litzen wire formed thereon are not suitable for taking up or transmitting the mechanical forces required for supporting the tube lamp.

Consequently there is a great need in practice for a lamp holder that is suitable for mechanically supporting a tube lamp of the above-described type provided with a contact element that projects from the end faces of the glass tube body, which contact element must not be subjected to inadmissible mechanical forces which may cause the contact element to break off or which may lead to damage at the transition from the contact element to the glass tube body.

To that end, the invention in a first aspect thereof provides a lamp holder of the kind referred to in the introduction, which is characterised in that the inner sleeve and the outer sleeve are formed such that the sleeves can rotate relative to each other about the longitudinal axis of the lamp holder in mounted condition so as to enable the contact member to electrically contact the wirelike electrical contact element.

With the lamp holder according to the invention, the mechanical forces for supporting and contacting the tube lamp are transmitted to the glass tube lamp body via the inner sleeve and taken up by the glass body. The contact element of the tube lamp is thus fully relieved of mechanical forces.

In an embodiment of the lamp holder according to the invention, the receiving opening in the inner sleeve opens into a slotted opening in the circumferential edge of the inner sleeve body, and in a preferred embodiment of the lamp holder according to the invention the receiving opening in the inner sleeve is formed by a slot extending in the inner sleeve body from the circumferential edge thereof, the slot having a first part for receiving the free end of the tube lamp and a second part adjacent to the first part for receiving the contact element of the tube lamp.

The inner sleeve can be slid over the end of the tube lamp and the contact element transversely to its longitudinal direction via the slot formed therein without exerting any appreciable forces. Preferably, the dimensions of the first part of the slot are adapted to ensure a close fit of the tube end therein, so that the tube end can be accommodated in the receiving opening as much as possible without play so as to provide an adequate mechanical support of the lamp to prevent vibrations in the lamp holder.

The outer sleeve may essentially be made up of a hollow cylinder, whose internal cavity is dimensioned to receive the inner sleeve with a close fit. After the inner sleeve has been placed on the tube lamp, the whole can be inserted into the outer sleeve in the longitudinal direction of the tube lamp for fitting and electrically connecting the lamp by turning the same.

In another embodiment of the lamp holder according to the invention, the receiving opening in the outer sleeve opens into a slotted opening in the circumferential edge of the outer sleeve body, and in another preferred embodiment of the lamp holder according to the invention, the receiving opening in the outer sleeve is formed by a cavity that extends in longitudinal direction therein, which cavity is dimensioned to rotatably receive the inner sleeve therein, with a slot formed in the circumferential edge of the body, which opens into the cavity, which slot has a first part adapted to receive the free end of the tube lamp and a second part connecting to the first part adapted to receive the contact element of the tube lamp.

This embodiment of the invention makes it possible to insert the tube lamp into the inner sleeve via the slot in the outer sleeve, in which the inner sleeve is already mounted. This can be done in such a manner that the tube lamp can be fitted in the lamp holder transversely to the longitudinal direction rather than in the longitudinal direction thereof. As a result, fitting the lamp holder according to the invention can take place in a relatively simple and quick manner, which is necessary when the lamps are used in the horticultural industry, for example, as in that case the lamps must be cleared of herbicides and the like that have precipitated thereon from time to time. It stands to reason that the above advantage also obtains when lamps, which are difficult to reach in some cases, are being replaced within the framework of maintenance.

Although the contact member of the lamp holder may have various forms, in an advantageous embodiment of the invention the contact member is essentially V-shaped, having a first leg and a second leg and a receiving opening formed between the two legs for receiving the wirelike contact element of the tube lamp.

The contact element can be received in the contact member without exerting any appreciable forces by spreading the two legs sufficiently far apart. In this way damage to the contact element itself and to the transition between the contact element and the glass lamp body is prevented in an effective manner.

In a preferred embodiment of the lamp holder according to the invention for use with a tube lamp provided with a wirelike contact element, for example of molybdenum, an essentially semicircular protrusion is formed transversely to the two legs of the contact member, in such a manner that the protrusions are positioned opposite each other, forming an essentially cylindrical receiving opening for the wirelike contact element.

This receiving opening in the contact member itself prevents the wirelike contact element from being bent or moved, for example upon rotation of the tube lamp about its longitudinal axis, and makes it possible to obtain a sufficiently low contact resistance between the contact element and the contact member.

Although there are several ways of providing the contact member of the lamp holder with contact terminals for connecting the same in a lighting fixture, for example by means of the aforesaid litzen wire, in a preferred embodiment of the invention the two legs of the V-shaped contact member blend into a contact bus for a contact pin near their fixed ends.

In another embodiment of the lamp holder according to the invention, the contact member is mounted in the cavity of the outer sleeve, in such a manner that the two legs join the second part of the slot formed in the outer sleeve body with their free ends and that the receiving opening for the wirelike contact element in the contact member is aligned with the central axis of the outer sleeve.

In a preferred embodiment of the lamp holder according to the invention, a chamber extends in radial direction in the outer sleeve from the circumferential edge thereof and terminates near the axial line of the outer sleeve, which chamber accommodates the contact member, in such a manner that the receiving opening of the contact member connects to the second part of the receiving opening in the outer sleeve.

Upon insertion of the tube lamp into the slot in the outer sleeve, the contact element is received between the two legs of the contact member, more in particular in the receiving opening for the wirelike contact element in the contact member. The alignment of the receiving opening of the contact member with the central axis of the tube lamp effectively prevents undesirable torsional and other mechanical twisting forces being exerted on the wirelike contact element of the tube lamp. To enable the two legs of the contact member to exert a sufficiently large contact force on the wirelike contact element, the invention, in yet another embodiment of the invention, provides stops extending into the outer sleeve for limiting the extent to which the two legs of the contact member can move apart. The inner sleeve has a receiving opening in the circumferential edge thereof for receiving the free ends of the legs of the contact member. Rotation of the inner sleeve relative to the outer sleeve will cause one leg of the contact member to move in the direction of the other leg, which is held in position by a respective stop, for the purpose of contacting the wirelike contact element of the tube lamp between the legs. In an preferred embodiment of the invention, the inner sleeve is provided with outwardly projecting stops for engaging a leg of the contact member for the purpose of moving the two legs of the contact member together by rotating the inner sleeve and the outer sleeve relative to each other through the exertion of a force so as to contact a wirelike contact element accommodated between the legs. Rotation of the inner sleeve and the outer sleeve relative to each other is possible in the lamp holder. according to the invention in that the respective receiving openings of the sleeves and the contact member are aligned in the longitudinal direction of the lamp holder. In yet another embodiment of the invention, in order to prevent undesirable removal of the tube lamp from the lamp holder according to the invention or of the inner sleeve from the outer sleeve, the inner sleeve and the outer sleeve are formed in such a manner that the sleeves can be moved into and out of a locked position by being rotated about the longitudinal axis of the lamp holder. In a preferred embodiment of the lamp holder, the lamp holder is provided with locking means made up of a spring washer present in the outer sleeve body, which partially surrounds the circumference of the cavity formed therein, which spring washer is provided with raised parts formed on the free ends thereof, and of recesses formed in the inner sleeve body, which are distributed over the outer circumference thereof, such that when the inner sleeve is rotated relative to the outer sleeve in mounted condition, at least one of the raised parts of the spring washer can engage in at least one recess.

The raised parts of the spring washer and the recesses in the inner sleeve are positioned to interlock when the inner sleeve and the outer sleeve are rotated about 30-60° relative to each other.

Interlocking the sleeves by rotating them relative to each other is a simple operation, which can be carried out quickly and at locations of the lamp that are difficult to reach, simultaneously with the making and/or breaking of the electrical contact between the contact member and the wirelike contact element. In yet another embodiment of the lamp holder according to the invention, the contact member is mounted in the inner sleeve in such a manner that the two legs join the second part of the sleeve formed in the inner sleeve body with their free ends.

By inserting the end of the tube lamp into the slot in the inner sleeve, the wirelike contact element is received between the two legs of the contact member without any appreciable mechanical force being exerted.

In the case of a contact member having a specially formed receiving opening for the contact element of the tube lamp, the contact member is according to the invention mounted in the inner sleeve in such a manner that the receiving opening for the wirelike contact element in the contact member is aligned with the central axis of the inner sleeve.

Especially for use with a contact element in the form of a litzen wire, as discussed in the foregoing, a recess is according to the invention formed in the outer circumference of the inner sleeve body, near the contact member, in the embodiment in which the contact member is accommodated in the inner sleeve, and a stop corresponding to the recess is formed in the cavity of the outer sleeve, the first leg of the contact member being freely accommodated in the recess and the second leg abutting against a boundary wall of the recess, the inner sleeve and the outer sleeve being formed in such a manner that the sleeves can rotate relative to each other about the longitudinal axis of the lamp holder in mounted condition, with the first leg of the spring means being blocked by the stop and the second leg being moved in the direction of the first leg for contacting the contact element of the tube lamp under the influence of a clamping force. The two legs of the contact member are now moved together by rotating the sleeves for clamping down the wirelike contact element of the tube lamp between the legs. As a result of the clamping force, a good electrical contact with the contact element with a sufficiently low electrical contact resistance is obtained, so that it is possible to use a flexible litzen wire as the contact element. In this embodiment, the locking means may advantageously be made up of a nose projecting outside the circumference of the inner sleeve body from the second leg of the contact member, and at least one recess formed in the circumferential wall of the outer sleeve cavity for receiving the nose, in such a manner that the nose can engage in a recess upon rotation of the inner sleeve relative to the outer sleeve in mounted condition.

In an embodiment thereof, the nose is positioned to engage in the second part of the slot formed in the outer sleeve for receiving the contact element of the tube lamp in the rotated position of the inner sleeve and the outer sleeve relative to each other. In this embodiment, too, the rotation required for effecting and releasing the locking engagement between the sleeves can be limited to about 30- 60° by suitably selecting the relative positions of the nose and the corresponding recesses.

As already noted before, fitting and locking the tube lamp can take place in a simple manner by rotating the lamp in longitudinal direction, thereby enabling a rapid fitting of the lamp.

In the embodiment in which the contact member is provided with a contact bus for receiving a contact pin, a contact part is according to the invention formed at the end of the outer sleeve body to which the second part of the slot formed therein is adjacent, which contact part comprises a contact pin that engages in and makes electrical contact with the contact bus of the contact member for electrically connecting a lamp holder in a lighting fixture or the like.

In the embodiment of the lamp holder in which the contact member is mounted in the inner sleeve, the dimensions of the contact pin and the contact bus have been selected so that the contact bus can rotate round the contact pin under a clamping force. To effect the required clamping force, the contact bus is formed as a folded-back protrusion, such that the contact bus can vary in diameter.

In yet another embodiment of the lamp holder according to the invention, the contact part is a plate-shaped body extending transversely to the outer sleeve body, which plate-shaped body comprises at least one contact terminal that is electrically connected to the contact pin. The plate-shaped body can form part of or fit in a lighting fixture in that case.

The inner sleeve may be formed of an electrically conductive material, if desired, but preferably, like the outer sleeve, it is made of a suitable electrically insulating material, such as a polymer material. Both the inner sleeve and the outer sleeve may be made of a polymer material which is resistant to high temperatures and ultraviolet radiation. The polymer material may comprise a high degree of glass fibre filling. The polymer material may be capable of withstanding prolonged exposure to temperatures of 145 ⁰C or higher, for example, and peak temperature loads of 240 ⁰C.

In a preferred embodiment of the invention, the contact member comprises a contact surface for receiving the contact element of the tube lamp that is provided with raised parts so as to reduce the current displacement effect in the contact member. The raised parts in the contact surface may have been formed by forming a wafer-like profile in the surface, or consist of teeth or the like, for example. Furthermore, the contact surface of the contact member may be coated with silver.

Suitable materials for the contact member of the lamp holder are in particular phosphorus bronze, a nickel-manganese alloy, a beryllium-copper alloy, a nickel alloy or a chromium-nickel-iron alloy. To ensure that a sufficiently large contacting force is exerted on the contact element of the tube lamp, the contact member is advantageously formed of leaf spring material.

In a third embodiment of the invention, centring means for centring a tube lamp in radial direction are provided in the receiving opening of the inner sleeve so as to effect an accurate positioning of the tube lamp in the radial direction of the lamp holder.

In a preferred third embodiment of the lamp holder according to the invention, the centring means comprise a wirelike spring element formed in one piece, with spring-loaded legs positioned adjacent to each other between which one end of a connecting piece of the tube lamp can be received.

With these centring means the tube lamp is not only precisely positioned in radial direction in order to effect an exact alignment thereof relative to a reflector in a lighting fixture, but the tube lamp is also protected against vibrations and the like. A tube lamp that is precisely aligned relative to a reflector has many advantages, both with regard to obtaining an improved directional effect and with regard to obtaining a higher lighting efficiency.

The invention also relates to an inner sleeve and an outer sleeve as discussed in the foregoing. The invention furthermore relates to a lighting fixture for a tube lamp, comprising at least two spaced-apart, opposed outer sleeves as discussed in the foregoing, for receiving between them at least one tube lamp provided with an associated inner sleeve according to the invention at each of its ends.

The invention furthermore relates to a tube lamp for use in such a lighting fixture, which tube lamp is provided with an inner sleeve as discussed in the foregoing at each of its ends.

The invention also relates to a method for electrically contacting, by means of a lamp holder as discussed in the foregoing, a tube lamp provided with an outwardly projecting, wirelike electrical contact element at each free end thereof, which method is characterised by the steps of

- placing each free end of the tube lamp into a lamp holder, in such a manner that the free end is positioned in the receiving opening of the inner sleeve, the inner sleeve is positioned in the receiving opening of the outer sleeve and the wirelike contact element is positioned in the receiving opening of the contact member of the lamp holder, and

- effecting an electrical contact between each wirelike contact element and the contact member of the lamp holder in question by rotating the inner sleeve and the outer sleeve of a lamp holder relative to each other. When a lamp holder is used in which the inner sleeve and the outer sleeve are provided with slotted openings in their circumferential edges, the method according to the invention in particular provides for the tube lamp to be simultaneously received in the receiving openings of the inner sleeve, the outer sleeve and the contact member of a respective lamp holder from the opposed slotted openings with its free ends and its wirelike contact elements, and for the contact member of a lamp holder to electrically contact the respective wirelike contact element of the tube lamp through rotation of the inner sleeve relative to the outer sleeve.

The invention will be explained in more detail hereinafter with reference to the appended drawings of an embodiment of a lamp holder for use with a so-called "Double Ended High Frequency Currency Lamp" as marketed by Philips. The invention is by no means limited to this type of tube lamp, however, and is generally suitable for use with any type of tube lamp comprising a wirelike contact element projecting from the end faces of the glass body. Figure 1 is a schematic, perspective view of one end of a "Double

Ended High Frequency Currency Lamp" made by Philips.

Figure 2 is a schematic, perspective view of a first embodiment of an inner sleeve of the lamp holder according to the invention.

Figure 3 is a schematic front view of a first end face of the inner sleeve that is shown in figure 2.

Figure 4 is a schematic view of the inner sleeve along the line IV-IV in figure 2.

Figure 5 is a schematic, perspective view of a first embodiment of an outer sleeve of the lamp holder according to the invention, which is mounted to a connecting plate for placement in a lighting fixture.

Figure 6 is a schematic view of the outer sleeve along the line Vl-Vl in figure 5.

Figure 7 is a schematic front view of a first end face of the outer sleeve that is shown in figure 6. Figure 8 is a schematic, perspective view of a first embodiment of a V-shaped contact member of the lamp holder according to the invention.

Figure 9 is a schematic, larger-scale front view of the contact member of figure 8. Figure 10 is a schematic, perspective view of a second embodiment of an inner sleeve of the lamp holder according to the invention with a contact member mounted therein.

Figure 11 is a schematic, perspective view of a second embodiment of an outer sleeve of the lamp holder according to the invention. Figure 12 is a schematic view of the second end faces of the fitted- together inner sleeve and outer sleeve of the second embodiment of the lamp holder according to the invention.

Figure 13 is a schematic view of the fitted-together inner sleeve and outer sleeve of figure 12 in a rotated position relative to each other. Figure 14 is a schematic view similar to figure 12, in which the contact member is provided with a contact bus.

Figure 15 is a schema tical view of one end of a tube lamp with a lamp holder according to the invention mounted thereto.

Figure 16 is a schematic view in longitudinal direction of a third embodiment of an inner sleeve of the lamp holder according to the invention.

Figure 17 is a schematic view of a first end face of the inner sleeve that is shown in figure 16.

Figure 18 is a schematic view of a second end face of the inner sleeve that is shown in figure 16. Figure 19 is a schematic view in longitudinal direction of a third embodiment of an outer sleeve of the lamp holder according to the invention.

Figure 20 is a schematic view of a first end face of the outer sleeve that is shown in figure 19.

Figure 21 is a schematic view of a second end face of the outer sleeve that is shown in figure 19.

Figure 22 is a schematic, perspective view of a third embodiment of a V-shaped contact member of the lamp holder according to the invention.

Figure 23 is a schematic, perspective view of an embodiment of centring means according to the invention. Figure 24 is a schematic, perspective view of a holder for receiving an outer sleeve of the lamp holder according to the invention therein.

In Figure 1 , numeral 1 indicates an elongate cylindrical tube lamp having a body 2 of glass, which blends with a substantially H-shaped glass connecting piece 3 at each of its ends, which connecting piece comprises a wirelike contact element 4 of an electrically conductive material, for example molybdenum, having a diameter of about 1-1.5 mm and a length of about 10-15 mm that projects in outward direction therefrom. A litzen wire 5 may be attached to the contact element 4, for example by means of a clamping element 6, for contact purposes, for example for electrically connecting the tube lamp 1 by soldering or by means of a contact terminal.

The tube lamp 1 is intended for use in a lighting fixture provided with an Electronic Ballast (EB) (not shown) for exciting the tube lamp 1 with a supply voltage of 40-140 kHz or higher. The litzen wire 5 effectively reduces the current displacement effect ("skinn effect") that occurs at these high frequencies.

In an embodiment of the tube lamp 1 according to Philips' "Double Ended High Frequency Currency Lamp", the tube lamp 1 has a diameter of about 32 mm. The H-shaped connecting pieces 3 have a length of about 30 mm and a width of about 24 mm. Figure 2 shows a first embodiment of an inner sleeve 10 of the lamp holder according to the invention. The inner sleeve 10 is built up of an elongate, cylindrical body 11 having a first end face 12 and a second end face 13. A slotted receiving opening 14 extends in the body 11 from the circumferential edge thereof. The receiving opening 14 has a first part 15, which opens into the first end face 12. The shape and the dimensions of the first part 15 of the receiving opening 14 are adapted to receive the connecting piece 3 of the tube lamp 1 therein.

A second part 16 of the receiving opening 14 in the body 11 is illustrated in broken lines, which second part is adjacent to the second end face 13 of the inner sleeve 10. The dimensions of the second part 16 are adapted to the dimensions of the contact element 4 of the tube lamp 1.

Figure 3 is a view of the end face 12 of the inner sleeve 10 that is shown in figure 2. The figure clearly shows that the first part 15 of the receiving opening 14 extends across the entire body 11 and that the second part 16 of the receiving opening 14 extends to slightly beyond the centre of the body 12. The first part 15 and the second part 60 of the receiving opening blend into one another.

Recesses 17, 18 formed with bevelled edges are provided at the circumferential edge, near the first end face 12, on either side of the receiving opening 14. Figure 4 is a view of the inner sleeve 10 along the line IV-IV in figure

2. The first part 15 and the second part 16 of the receiving opening are clearly shown, and the second part 16 of the receiving opening opens into a receiving opening 19 of the body 11.

Figure 5 shows a first embodiment of an outer sleeve 20 of the lamp holder according to the invention. The outer sleeve 20 is built up of an elongate, cylindrical body 21 having a first end face 22 and a second end face 23. A slotted receiving opening 24 extends in the body 21 from the circumferential edge thereof. The receiving opening 24 has a first part 15, which opens into the first end face 22. The shape and the dimensions of the first part 25 of the receiving opening 24 are adapted to receive the connecting piece 3 of the tube lamp 1 therein.

The slotted opening 24 has a second part 26 adjacent to the second end face 23 of the outer sleeve 20. In this case too, the dimensions of the second part 26 are adapted to conform to the dimensions of the contact element 4 of the tube lamp 1. The first part 25 and the second part 26 of the receiving opening 24 blend into one another, as is clearly shown in figure 6, which is a view of the outer sleeve 20 along the line Vl-Vl in figure 5.

The receiving opening 24 of the outer sleeve 20 extends in the body from the first end face 22 to the second end face 23 and is dimensioned to receive the inner sleeve 10 for rotation about the longitudinal axis 27 of the outer sleeve 20 therein.

Two elongate stops 28, 29 extend in the receiving opening 24 of the outer sleeve from the second end face 23 thereof, as is shown in broken lines in figure 5 and figure 6.

Figure 7 is a view of the first end face 22 of the outer sleeve 20. A spring washer 30 having raised parts 31 , 32 at the ends thereof is shown to be present near the circumference. The raised parts 31 , 32 are formed to extend a specified radial distance into the receiving opening 24 of the outer sleeve.

In figures 5-7 the outer sleeve 20 is mounted to a connecting plate 35 via its second end face 23. The shape and the dimensions of the connecting plate are adapted for fitting the connecting plate in a lighting fixture (not shown). Such a connecting plate may be an integral part of the outer sleeve 20 of the lamp holder according to the invention, or be accommodated as a separate part or as an integrated part of a fixture suitable for use with a lamp holder according to the invention. The connecting plate 35 has a contact pin 36 that extends in the outer sleeve 20 from the second end face 23. A conductor 37 extends from the contact pin 36 to an end edge of the connecting plate 35 and may terminate in a contact terminal or plug pin or other type of connector 38 at that location for connection to an electric supply source, such as an Electronic Ballast. Figure 8 shows an essentially V-shaped contact member 40 of an electrically conductive material having first and second legs 41 , 42, which form an opening 43 at their free ends.

As is shown on a larger scale in figure 9, the two legs 41 , 42 are each provided with a semicircular protrusion 44 and 45, respectively, extending across the width of the legs. The two protrusions 44, 45 are positioned opposite each other and form an essentially cylindrical receiving opening 46 for receiving the contact element 4, 5 of the tube lamp 1 therein from the opening 43 that is present between the two legs 41 , 42. The dimensions of the two protrusions are adapted to conform to the thickness and the length of the contact element 4, 5. In the illustrated embodiment of the contact member 40, the two legs 41 , 42 blend with a contact bus 47 for clampingly receiving a contact pin therein.

In the assembled condition of the lamp holder in the first embodiment of the invention, the contact member 40 is accommodated in the outer sleeve 20 near the second end face 23, in such a manner that the outward movement of the two legs 41 , 42 is limited by the stops 28, 29. The free ends of the two legs 41 , 42 engage in the receiving opening 19 of the body 11 of the inner sleeve 10. The contact bus 47 engages round the contact pin 36 of the connecting plate 35. The opening 43 between the two legs 41 , 42 of the contact member 40 connects to the second part 26 of the receiving opening 24 in the outer sleeve 20. In the embodiment that comprises a cylindrical receiving opening 46 for the contact element 4, 5 of the tube lamp 1 , the receiving opening 46 is exactly in line with the central axis 27 of the outer sleeve 20.

The inner sleeve 10 and the outer sleeve 20 are mounted in such a manner that the receiving opening 14 of the inner sleeve 10, the receiving opening 24 of the outer sleeve 20 and the receiving opening 46 of the contact member 40, if the opening is cylindrical in shape, are all aligned in the longitudinal direction of the lamp holder and that respective receiving openings 14 and 24 are positioned opposite each other to enable insertion of the connecting piece 3 with the contact element 4, 5 of the tube lamp 1 from the circumferential edge of the outer sleeve 20.

By subsequently turning the tube lamp 1 and with it the inner sleeve 10 approximately 30-60° about its longitudinal axis, one of the two legs 41 , 42 of the contact member 40 is moved in the direction of the other leg as a result of the rotation of the receiving opening 19 in the inner sleeve 10, which other leg is blocked against movement by a stop 28, 29 of the outer sleeve 20, for electrically contacting the wirelike contact element 4, 5 of the tube lamp 1 between the two legs 41 , 42 in this manner.

During the rotation, one of the raised parts 31 , 32 of the spring washer 30 engages in a recess 17 or 18 of the inner sleeve 10, depending on the direction of rotation of the tube lamp 1 , for interlocking the inner sleeve 10 and the outer sleeve 20. This prevents the tube lamp from falling out of the lamp holder 1 in fitted condition, for example due to shocks or impacts or the like.

The raised parts 31 , 32 may be formed as cams, in such a manner that they form a stop (not shown), for example by interacting with the recesses 17 and 18, to protect the tube lamp against being rotated too far. Such a stop may also be formed by a stop (not shown) in the outer sleeve 20, for example, which interacts with a suitably shaped opening (not shown) in the inner sleeve 10, for example near the second end face 23 of the outer sleeve 20, as is achieved in a corresponding manner by the stop 78 and the recess 57 in the further embodiment of the invention as discussed below.

In this way the tube lamp 1 is mechanically supported by the lamp holder via the connecting piece 3 thereof, with no mechanical forces or no appreciable mechanical forces being exerted on the wirelike contact element 4.

Figure 10 shows a second embodiment of the lamp holder according to the invention, which comprises an inner sleeve 50. The inner sleeve 50 is built up of an elongate, cylindrical body 51 having a first end face 52 and a second end face 53. A slotted receiving opening 54 extends in the body 51 from the circumferential edge thereof. The receiving opening 54 has a first part 55, which opens into the first end face 52. In this case, too, the shape and the dimensions of the first part 55 of the receiving opening 54 are adapted to receive the connecting piece 3 of the tube lamp 1 therein.

The receiving opening 54 has a second part 56 adjacent to the second end face 53 of the inner sleeve 50, which opens into the first part 55. Also in this case, the dimensions of the second part 56 are adapted to receive the contact element 4 of the tube lamp 1.

At the second end face 53 of the body 51 , a recess 57 extending over approximately 1/4 of the circumference of the body 51 is formed in the body from the circumferential edge thereof. An essentially V-shaped contact member 60 of an electrically conductive material having a first leg 61 and a second leg 62 is present in the inner sleeve 50 near the aforesaid recess. The first leg 61 is loosely accommodated in the recess 57 and the second leg 62 abuts against the boundary wall 58 of the second part 56 of the receiving opening 54.

The free ends of the legs 61 , 62 form an opening 63 that connects to the second part 56 of the receiving opening 54 for receiving the contact element 4 of the tube lamp 1 between the two legs 61 , 62. The fixed ends of the legs 61 , 62 of the contact member 60 form a receiving opening 64 for receiving the wirelike contact element 4. The receiving opening 64 extends in the longitudinal direction of the central axis 59 of the inner sleeve 50. Figure 11 shows a second embodiment of an outer sleeve 70 of the lamp holder according to the invention. The outer sleeve 70 is built up of an elongate, cylindrical body 71 having a first end face 72 and a second end face 73. A slotted receiving opening 74 extends in the body 71 from the circumferential edge thereof. The receiving opening 74 comprises a first part 75, which opens into the first end face 72. The shape and the dimensions of the first part 75 of the receiving opening 74 are adapted to receive the connecting piece 3 of the tube lamp 1 therein.

The slotted receiving opening 74 has a second part 76 adjacent to the second end face 73 of the outer sleeve 70. Also in this case, the dimensions of the second part 76 are adapted to receive the contact element 4 of the tube lamp 1. The first part 75 and the second part 76 of the receiving opening 74 blend into one another. In this embodiment, the second part 76 of the receiving opening 74 does not open into the second end face 73 of the outer sleeve 70.

The receiving opening 74 of the outer sleeve 70 extends from the first end face 72 to the second end face 73 in the body 71 , its dimensions being adapted for accommodating the inner sleeve 50, in such a manner that the inner sleeve 50 is capable of rotation about the longitudinal axis 77 of the outer sleeve 70 therein.

Figure 12 is a view of the second end faces 53, 73 of the fitted- together inner sleeve 50 and outer sleeve 70. The inner sleeve 50 and the outer sleeve 70 are fitted together in such a manner that the receiving opening 54 of the inner sleeve 50, the receiving opening 74 of the outer sleeve 70 and the receiving opening 64 of the contact member 60 are aligned in the longitudinal direction of the lamp holder and that respective receiving openings 54 and 74 are positioned opposite each other to enable insertion of the connecting piece 3 with the contact element 4 of the tube lamp 1 from the circumferential edge of the outer sleeve 70.

Near the second end face 73, a stop 78 extends in the receiving opening 74 of the outer sleeve over approximately 1/4 of the circumference. The position and the dimensions of the stop 78 correspond to the position of the recess 57 in the inner sleeve 50, such that the inner sleeve 50 can turn about 30-60° in the outer sleeve 70 when mounted therein, wherein the first leg 61 of the contact member 60 is blocked against rotation by the stop 78.

Figure 12 shows that the second leg 62 of the contact member 60 has an extension 65 provided with a nose-shaped projection 66, which projection engages in a recess 79 in the inner circumference of the inner sleeve 70. The projection 66 and the recess 79 have upwardly sloping sides for moving the nose- shaped projection out of the recess 79 by turning the inner sleeve 50.

As a result of the turning or rotation, the two legs 61 , 62 are pressed together and the nose-shaped projection 66 will eventually engage in the second part 76 of the receiving opening 74 of the outer sleeve 70 so as to block the inner sleeve 50 against backward rotation.

The contact element 4 of the tube lamp 1 is clamped down firmly in the receiving opening 64 of the contact member 60. The fact that the two legs 61 , 62 of the contact member 60 are clamped together renders this second embodiment of the lamp holder according to the invention highly suitable for contacting a contact element 5 formed of litzen wire of the tube lamp. This can be realised through interaction with the second part 76 of the receiving opening 74, which does not continue as far as the second end face 73 of the outer sleeve 70, so that a litzen wire functioning as the contact element 5 of the tube lamp 1 is bent between the two legs 61 , 62 of the contact member 60.

To reduce the current displacement effect in the contact member 60 as much as possible, the contact member is preferably provided with projections or raised parts 68, as is shown schematically in figure 12 and figure 13. These raised parts or projections 68 can be created by forming the contact surface of the contact member 60 with, for example, a wafer-like profile.

Figure 14 shows another embodiment of the inner sleeve 50 in mounted condition in the outer sleeve 70, seen from the second end faces 53, 73, with a V-shaped contact member 80 having legs 81 , 82, which are provided with a contact bus 83 formed by folding back the legs, which functions to rotatably accommodate a contact pin therein, such as the contact pin 36 of the connecting plate 35, as described above. In figure 14 the contact surface of the contact member has cross teeth 84, which function to reduce the current displacement effect therein.

Figures 16-21 show a third embodiment of the lamp holder according to the invention. Figure 16 shows a third embodiment of an inner sleeve 90 of the lamp holder according to the invention. Also in this case, the inner sleeve 90 is built up of an elongate, cylindrical body 91 having a first end face 92 and a second end face 93. A slotted receiving opening 94 extends in the body 91 from the circumferential edge thereof. The receiving opening 94 comprises a first part 95, which opens into the first end face 92. The shape and the dimensions of the first part 95 of the receiving opening 94 are adapted to receive the connecting piece 3 of the tube lamp 1 therein.

There is shown a second part 96 of the receiving opening 94 in the body 91 , which second part is adjacent to the second end face 93 of the inner sleeve 90. Also in this case, the dimensions of the second part 96 are adapted to conform to the dimensions of the contact element 4 of the tube lamp 1.

Two elongate legs 97, 98 extend outwards, parallel to the longitudinal direction of the elongate inner sleeve 90, from the second end face 93, transversely to the plane thereof. The body 91 furthermore has a flanged edge or collar 111 circumferentially formed thereon.

Furthermore, centring means for the tube lamp 2 in the form of a wirelike, spring element 100 are provided in the first part 95 of the receiving opening 94. The spring element 100 comprises two legs 102 and 103, which are movable relative to each other against the spring force of the element 100. A receiving W

19 opening 101 is present between the legs 102, 103 for receiving the connecting piece 3 of the lamp 1 therebetween from the receiving opening 94 upon fitting of the lamp 1 in the inner sleeve 90. In the position of rest of the spring element 100, the legs 102, 103 are positioned adjacent to each other near the end face 92 of the inner sleeve 90 under the influence of the spring force.

Figure 17 is a view of the end face 92 of the inner sleeve 90 that is shown in figure 16. In this embodiment, the first part 95 of the receiving opening 94 does not extend across the entire body 91 , unlike the first embodiment of the lamp holder according to the invention, but terminates in a boundary wall 99. The second part 96 of the receiving opening 94 extends from the second end face 93 to substantially the centre of the body 91. The first part 95 and the second part 96 of the receiving opening 94 blend into one another.

A recess 112 is formed in the collar 111 at the first end face 92. Figure 18 is a view of the second end face 93 of the inner sleeve 90. The figure clearly shows the second part 96 of the receiving opening 94, which has a smaller internal opening than the first part 95. The figure also shows the slotted recesses 106 and 107, in which the spring element 100 engages with its free ends 105 and 104, respectively.

In the illustrated embodiment, the spring element 100 is formed of one piece of spring wire, having two ends 104, 105 which engage in small recesses 106, 107 (see figure 18) formed in the body 91 at the transition between the first part 95 and the second part 96 of the slotted opening 94. The spring element 100 engages in a slotted recess 110 with a connecting piece 109 between the two legs 102, 103 thereof, which slotted recess is likewise formed at the transition between the first part 95 and the second part 96 of the slotted opening 94 in the body 91.

In use, the connecting piece 3 of the tube lamp 1 engages between the two legs 103 and 104 of the spring element 100 for the purpose of precisely centring the tube lamp 1 in the receiving opening 94. The legs 103, 104 of the spring element 100 engage a precisely formed (with narrow tolerances) part of the tube lamp 1 , viz. the H-shaped connecting piece 3. Upon placement of the tube lamp 1 in a lighting fixture provided with a reflector, the tube lamp 1 will thus be positioned precisely in the focal line of the reflector, so that an optimum directional effect and a maximum light output are ensured.

Figure 19 shows a third embodiment of an outer sleeve 120 of the lamp holder according to the invention. The outer sleeve 120 is built up of an elongate, cylindrical body 121 having a first end face 122 and a second end face 123. A slot that the receiving opening 124 extends in the body 121 from the circumferential edge thereof. The receiving opening 124 has a first part 125, which opens into the first end face 122. The shape and the dimensions of the first part 125 of the receiving opening 124 have been adapted to receive the connecting piece 3 of the tube lamp 1 therein.

The slotted opening 124 has a second part 126 adjacent to the second end face 123 of the outer sleeve 120. In this case too, the dimensions of the second part 126 are adapted to conform to the dimensions of the contact element 4 of the tube lamp 1. The first part 125 and the second part 126 of the receiving opening 124 blend into one another.

The receiving opening 124 of the outer sleeve 120 extends in the body 121 from the first end face 122 to the second end face 123 and is dimensioned to receive the inner sleeve 90 for rotation about the longitudinal axis 127 of the outer sleeve 120 therein.

Figure 20 is a view of the first end face 122 of the outer sleeve 120. A spring washer 130 having raised parts 131 , 132 at the ends thereof is shown to be present near the circumference of the body 121 , which spring washer extends along approximately half the circumference. The raised parts 131 , 132 are formed to extend a specified radial distance into the outer sleeve 120.

Figure 21 is a view of the second end face 123 of the outer sleeve 120.

At the second end face 123, a chamber 128 extends radially into the outer sleeve 120 in the second part 126 of the receiving opening 124. The chamber 128 terminates in a V-shape 129 near the axial line 127 of the body 121. The chamber 128 accommodates a spring contact member 130. The contact member 133 is substantially V-shaped, with the opening of the V-shape connecting to the second part 126 of the receiving opening 124. Figure 22 shows the essentially V-shaped contact member 133 of electrically conductive material having first and second legs 134, 135 connected to each other via a connection part or base part 136. At their free ends the legs form an opening 137 for receiving therebetween a contact end 4 of the litzen wire 5 of the tube lamp 1. As is shown in figure 22, the two legs 134, 135 are each provided with a longitudinally extending slotted opening 138, thus providing two halves capable of independent springing movement relative to each other. This makes it possible in an advantageous manner to contact relatively short as well as relatively long contact ends without any loss of clamping force. That is, relatively short contact ends which only engage one half of a leg 134, 135 and relatively long contact ends which engage both halves of a leg 134, 135.

A contact lip 139 is formed on the base part 136 for connecting a current conductor in a manner that is known per se. Figure 23 is a schematic, perspective view of the above-discussed embodiment of the centring means in the form of the spring element 100. The exact shape of the spring element 100 is determined in part by the desired clamping force for moving the legs 102, 103 apart when the connecting piece 3 of the tube lamp 1 is received therebetween from the opening 101. A tube lamp 1 that is clamped down in the receiving opening 94 in this manner is centred in radial direction, capable of withstanding vibrations, and is automatically and precisely aligned in a lighting fixture.

Any suitable spring material, such as a chromium-nickel alloy, may be used as the material for the spring element 100. In an embodiment of the invention, the spring element 100 is made of spring wire having a diameter of 0.5- 1 mm. It will be understood that the illustrated embodiment is an example of many possible variants of centring means according to the invention.

In the assembled condition of the lamp holder according to the third embodiment of the invention, the contact member 133 is accommodated in the chamber 128 in the outer sleeve 120 near the second end face 123, in such a manner that the extent to which the two legs 134, 135 can move apart in the chamber is limited. The opening 137 between the two legs 134, 145 of the contact member 133 connects to the second part 126 of the receiving opening 124 in the outer sleeve 120. The inner sleeve 90 and the outer sleeve 120 are mounted in such a manner that the receiving opening 94 of the inner sleeve 90, the receiving opening 124 of the outer sleeve 120 and the receiving opening 137 of the contact member 133 are aligned in the longitudinal direction of the lamp holder and that the respective receiving openings 94 and 124 are positioned opposite each other to enable insertion of the connecting piece 3 with the contact element 4 of the tube lamp 1 from the circumferential edge of the outer sleeve 20 and between the two legs 102, 103 of the spring element 100 for precisely centring the tube lamp 1.

By subsequently turning the tube lamp 1 approximately 30-60° about its longitudinal axis, one of the raised parts 131 , 132 of the spring washer 130 engages in the recess of the inner sleeve 90, depending on the direction of rotation of the tube lamp 1 , for interlocking the inner sleeve 90 and the outer sleeve 120. This prevents the tube lamp 1 from falling out of the lamp holder in fitted condition, for example due to shocks or impacts or the like. The raised parts 131 , 132 may be formed as cams, in such a manner that they form a stop (not shown), for example by interacting with the recess 112, to protect the tube lamp against being rotated too far.

In this way the tube lamp 1 is mechanically supported by the la,mp holder via the connecting piece 3 thereof, with no mechanical forces or no appreciable mechanical forces being exerted on the wirelike contact element 4.

By rotating the inner sleeve 90 with the tube lamp 1 with respect to the outer sleeve 120 that is fixedly mounted in a lighting fixture, one of the legs 97, 98 engages a leg 135, 134 of the contact member 133 for moving the two legs 134, 135 together with a contact end 4 or litzen wire 5 of the tube lamp received therebetween while exerting a force for the purpose of firmly and adequately contacting the tube lamp 1. It depends on the direction of rotation of the inner sleeve 90 relative to the outer sleeve 120 which of the two legs 134, 135 presses against a leg of the contact body.

Figure 24 is a schematic, perspective view of a holder 140 provided with a receiving opening 141 for receiving the outer sleeve 120 with the second end face 123 therein. The holder 140 has a connecting plate 142, whose shape and dimensions are adapted for being mounted in a lighting fixture (not shown). Such a connecting plate may be an integral part of the outer sleeve 120 of the lamp holder according to the invention, or be accommodated as a separate part or as an integrated part of a fixture suitable for use with a lamp holder according to the invention.

In the illustrated embodiment, the body 121 of the outer sleeve 120 has barblike lips 143, which engage in suitably shaped recesses 144 in the holder 140 for locking the outer sleeve 120 to the holder. The dimensions of the inner sleeve 10, 50, 90 and the outer sleeve

20, 70, 120 are adjusted to each other, such that the inner sleeve can rotate within the outer sleeve with a close fit, whilst sufficient play is available to accommodate heat-induced expansion, so that the sleeves will not seize. The sleeves have a diameter that corresponds to the diameter of the tube lamp 1.

The sleeves 10, 20, 50, 70, 90, 120 are preferably formed of one piece of an electrically insulating material, such as a polymer material. The inner sleeve may be made of an electrically conductive material, if desired.

Figure 15 is a schematic view of one end of a tube lamp 1 with a lamp holder according to the invention fitted thereto.

Suitable materials for the contact member 40, 60, 80, 133 of the lamp holder are in particular phosphorous bronze, a nickel-manganese alloy or a beryllium-copper alloy. To ensure that sufficient contact force is exerted on the contact element 4 of the tube lamp 1 , the contact member 40, 60, 80, 133 is advantageously formed of about 0.3-0.8 mm thick leaf spring material. Furthermore, the contact member 40, 60, 80, 133 may comprise a contact surface that is coated with silver for receiving a contact element 4 of the tube lamp 1.

Although the invention has been explained on the basis of three embodiments thereof in the foregoing, it will be appreciated by those skilled in the art that many modifications and adaptations thereto are possible without departing from the inventive concept. All these modifications and adaptations shall be considered to be incorporated in the appended claims.

Claims

1. A lamp holder for supporting and electrically contacting a tube lamp at, at least one free end thereof that is provided with an outwardly projecting, wirelike electrical contact element, which lamp holder is elongate in shape, comprising:

- an inner sleeve in the form of an essentially cylindrical body having a circumferential edge that defines a longitudinally extending receiving opening in the inner sleeve for receiving a free end of the tube lamp therein, - an outer sleeve in the form of an essentially cylindrical body having a circumferential edge that defines a longitudinally extending receiving opening extending in the outer sleeve for receiving the inner sleeve therein, and

- an electrical contact member provided with a receiving opening for receiving the wirelike contact element therein, wherein the receiving openings of the inner sleeve, the outer sleeve and the contact member are aligned in the longitudinal direction of the lamp holder, characterised in that the inner sleeve and the outer sleeve are formed such that the sleeves can rotate relative to each other about the longitudinal direction of the lamp holder in mounted condition so as to enable the contact member to electrically contact the wirelike electrical contact element.

2. A lamp holder according to claim 1 , characterised in that the receiving opening in the inner sleeve opens into a slotted opening in the circumferential edge of the inner sleeve body.

3. A lamp holder according to claim 1 or 2, characterised in that the receiving opening in the inner sleeve is formed by a slot extending in the inner sleeve body from the circumferential edge thereof, said slot having a first part for receiving the free end of the tube lamp and a second part adjacent to said first part for receiving the contact element of the tube lamp.

4. A lamp holder according to claim 2 or 3, characterised in that the receiving opening in the outer sleeve opens into a slotted opening in the circumferential edge of the outer sleeve body.

5. A lamp holder according to claim 2, 3 or 4, characterised in that the receiving opening in the outer sleeve is formed by a cavity that extends in longitudinal direction therein, which cavity is dimensioned to rotatably receive the inner sleeve therein, with a slot formed in the circumferential edge of the body, which opens into the cavity, which slot has a first part adapted to receive the free end of the tube lamp and a second part connecting to said first part adapted to receive the contact element of the tube lamp.

6. A lamp holder according to any of the preceding claims, characterised in that the contact member is essentially V-shaped, having a first leg and a second leg and a receiving opening formed between the two legs for receiving the wirelike contact element of the tube lamp.

7. A lamp holder according to claim 6, characterised in that an essentially semicircular protrusion is formed transversely to the two legs of the contact member, in such a manner that the protrusions are positioned opposite each other, forming an essentially cylindrical receiving opening for the wirelike contact element.

8. A lamp holder according to claim 7, characterised in that the two legs blend into a contact bus for a contact pin near their fixed ends.

9. A lamp holder according to claim 6, 7 or 8 in dependence on claim 5, characterised in that the contact member is mounted in the cavity of the outer sleeve, in such a manner that the two legs join the second part of the slot formed in the outer sleeve body with their free ends and that the receiving opening for the wirelike contact element in the contact member is aligned with the central axis of the outer sleeve.

10. A lamp holder according to claim 9, characterised in that stops extending into the outer sleeve are provided for limiting the relative movement of the two legs of the contact member.

11. A lamp holder according to claim 9 or 10 in dependence on claim 5, characterised in that a chamber extends in radial direction in the outer sleeve from the circumferential edge thereof and terminates near the axial line of the outer sleeve, which chamber accommodates the contact member, in such a manner that the receiving opening of the contact member connects to the second part of the receiving opening in the outer sleeve.

12. A lamp holder according to claim 9, 10 or 11 , characterised in that the inner sleeve is provided with outwardly projecting stops for engaging a leg of the contact member for the purpose of moving the two legs of the contact member together by rotating the inner sleeve and the outer sleeve relative to each other through the exertion of a force so as to contact a wirelike contact element accommodated between said legs.

13. A lamp holder according to claim 6, 7, 8, 9, 10, 11 or 12, in dependence on claim 3, characterised in that the second part of the slot in the inner sleeve opens into a receiving opening in the circumferential edge of the inner sleeve for receiving the free ends of the legs of the contact member in the receiving opening.

14. A lamp holder according to claim 6, 7 or 8, in dependence on claim 3, characterised in that the contact member is mounted in the inner sleeve in such a manner that the two legs join the second part of the sleeve formed in the inner sleeve body with their free ends.

15. A lamp holder according to claim 14, characterised in that the contact member is mounted in the inner sleeve in such a manner that the receiving opening for the wirelike contact element in the contact member is aligned with the ^• central axis of the inner sleeve.

16. A lamp holder according to claim 14 or 15, characterised by a recess formed in the outer circumference of the inner sleeve body, near the contact member, and a corresponding stop formed in the receiving opening of the outer sleeve, the first leg of the contact member being freely accommodated in the recess and the second leg abutting against a boundary wall of the recess, said inner sleeve and said outer sleeve being formed in such a manner that the sleeves can rotate relative to each other about the longitudinal axis of the lamp holder in mounted condition, with the first leg of the spring means being blocked by the stop and the second leg being moved in the direction of the first leg for contacting the contact element of the tube lamp under the influence of a clamping force.

17. A lamp holder according to claim 16, characterised by locking means made up of a nose projecting outside the circumference of the inner sleeve body from the second leg of the contact member, and at least one recess formed in the circumferential wall of the outer sleeve cavity for receiving the nose, in such a manner that the nose can engage in a recess upon rotation of the inner sleeve relative to the outer sleeve in mounted condition.

18. A lamp holder according to claim 17, characterised in that the nose is positioned to engage in the second part of the slot formed in the outer sleeve for receiving the contact element of the tube lamp in the rotated position of the inner sleeve and the outer sleeve relative to each other.

19. A lamp holder according to any of the preceding claims, in dependence on claim 8, characterised in that a contact part is formed on the outer sleeve body, which contact part comprises a contact pin that engages in and makes electrical contact with the contact bus of the contact member for electrically connecting the lamp holder.

20. A lamp holder according to claim 19, characterised in that the contact part is a plate-shaped body extending transversely to the outer sleeve body, which plate-shaped body comprises at least one contact terminal that is electrically connected to the contact pin.

21. A lamp holder according to claim 19 or 20, characterised in that the dimensions of the contact pin and the contact bus have been selected so that the contact bus can rotate round the contact pin under a clamping force, to which end the contact bus is formed as a protrusion folded back from the contact member, such that the contact bus can vary in diameter.

22. A lamp holder according to any of the preceding claims, characterised in that the inner sleeve and the outer sleeve are formed in such a manner that the sleeves can be moved into and out of a locked position by being rotated about the longitudinal axis of the lamp holder.

23. A lamp holder according to claim 22, characterised in that said locking means are made up of a spring washer present in the outer sleeve body, which partially surrounds the circumference of the receiving opening formed therein, which spring washer is provided with raised parts formed on the free ends thereof, and of recesses formed in the inner sleeve body, which are distributed over the outer circumference thereof, such that when the inner sleeve is rotated relative to the outer sleeve in mounted condition, at least one of the raised parts of the spring washer can engage in at least one recess.

24. A lamp holder according to any of the preceding claims, characterised in that the inner sleeve and the outer sleeve are formed of an electrically insulating material, such as a polymer material.

25. A lamp holder according to claim 24, wherein the polymer material is capable of withstanding exposure either to temperatures in excess of 100 ⁰C or to ultraviolet radiation, or both.

26. A lamp holder according to any of the preceding claims, characterised in that the contact member comprises a contact surface for receiving the contact element of the tube lamp that is provided with raised parts.

27. A lamp holder according to claim 26, characterised in that said raised parts in the contact surface have been formed by forming a wafer-like profile in said surface.

28. A lamp holder according to claim 26, characterised in that said raised parts are formed by teeth.

29. A lamp holder according to any of the preceding claims, characterised in that the contact member has a contact surface that is coated with silver for receiving the contact element of the tube lamp.

30. A lamp holder according to any of the preceding claims, characterised in that the contact member is made of spring leaf material.

31. A lamp holder according to any of the preceding claims, characterised in that the contact member is made of phosphorus bronze, a nickel- manganese alloy, a beryllium-copper alloy, a nickel alloy or a chromium-nickel-iron alloy.

32. A lamp holder according to any of the preceding claims, characterised in that centring means for centring a tube lamp in radial direction are provided in the receiving opening of the inner sleeve.

33. A lamp holder according to claim 32, characterised in that the centring means comprise a wirelike spring element formed in one piece, with spring- loaded legs positioned adjacent to each other between which one end of a connecting piece of the tube lamp can be received.

34. An inner sleeve for a lamp holder according to any of the preceding claims.

35. An outer sleeve for a lamp holder according to any of the preceding claims.

36. A lighting fixture for a tube lamp, comprising at least two spaced- apart, opposed outer sleeves according to claim 35, between which at least one tube lamp provided with an inner sleeve according to claim 34 at each of its ends can be received.

37. A tube lamp suitable for use in a lighting fixture according to claim 36, which tube lamp is provided with an inner sleeve according to claim 34 at each of its ends.

38. A method for electrically contacting, by means of a lamp holder according to any of the claims 1-33, a tube lamp provided with an outwardly projecting, wirelike electrical contact element at each free end thereof, characterised by the steps of - placing each free end of the tube lamp into a lamp holder, in such a manner that the free end is positioned in the receiving opening of the inner sleeve, the inner sleeve is positioned in the receiving opening of the outer sleeve and the wirelike contact element is positioned in the receiving opening of the contact member of the lamp holder, and - effecting an electrical contact between each wirelike contact element and the contact member of said lamp holder by rotating the inner sleeve and the outer sleeve of a lamp holder relative to each other.

39. A method according to claim 38, wherein the inner sleeve and the outer sleeve are provided with slotted openings in their circumferential edges, characterised in that the tube lamp is simultaneously received in the receiving openings of the inner sleeve, the outer sleeve and the contact member of a respective lamp holder from said opposed slotted openings with its free ends and its wirelike contact elements, and in that the contact member of said lamp holder electrically contacts the respective wirelike contact element of the tube lamp through rotation of the inner sleeve relative to the outer sleeve.