GB2127138A - Structural element - Google Patents

Abstract

A structural element of a frame comprises a tube (13) of light- transmitting material and contains a cold-cathode fluorescent tube (23). The tube is connected at its ends with similar or other structural elements via connectors (10) by means of a screw mechanism having a screw with head 15, male screw thread 16 adjacent to its other end, an annular plug 17, tubular spacer 18 constrained by a key 19, which key is fixed in the screw and engages in a slot 20 formed in the spacer so that the spacer can undergo limited movement along the shank of the screw. <IMAGE>

Description

SPECIFICATION Tube for use as a structural element This invention relates to a tube for use as a structural element in a frame. By a tube, I mean an elongate, hollow member having a circumferential wall which defines a longitudinal axis of the tube, the circumferential wall being spaced from and extending around the axis. Frames for supporting objects are commonly constructed by joining a number of tubes to one another.

According to a first aspect of the present invention, there is provided a tube having a circumferential wall of robust, light transmitting material, an electrically energisable light source disposed within the tube and electrical terminals connected with the light source.

By the description "robust" I mean the material is less fragile than the glass used heretofore for the circumferential walls of the tubes which contain electrically energisable light sources. A tube in accordance with the invention can be used as a structural element in a frame.

Preferably, both the light source and the terminals are spaced from ends of the tube. With this arrangement, end portions of the tube can be used for mechanical connection of the tube with further structural elements whilst electrical connections with the light source are maintained clear of the end portions of the tube.

According to a second aspect of the invention, there is provided a frame comprising a plurality of connecting bodies and a plurality of elongate elements connected together by said bodies, wherein at least one of the elements is a tube, has a circumferential wall of light-transmitting material and contains an electrically energisable light source.

An example of a frame according to the second aspect of the invention and incorporating a tube according to the first aspect ofthe invention, will now be described with reference to the accompanying drawing wherein: Figure 1 illustrates a part of the frame in perspec tiveviewfrom beneath; and Figure 2 shows a longitudinal cross-section of the tube, together with certain adjacent parts.

The frame illustrated in Figure 1 is in the form of an arch and comprises a number of identical connecting bodies 10 and a further number of elongate elements, one of which is indicated by the reference numeral 11 and others of which are indicated by the reference numeral 12. The elongate elements are releasably connected together by the connecting bodies 10. The elongate elements 12 comprise metal tubes having at their ends connectors with male screw threads engaged in threaded bores formed in the bodies 10. Each body 10 has a number of threaded bores, a selection of which is used, depending upon the relative directions of the several elongate elements connected with a particular body 10.Suitable connecting bodies and elongate elements for construction of the frame shown in Figure 1 are known, for example those sold under the Trade Mark "MEROFORM" by Mero-Raumstruktur GmbH & Co. of Wuerzburg.

The elongate element 11 differs from the elongate elements 12 and comprises a tube having a circumferential wall 13 formed of a robust lighttransmitting material which does not readily burn.

The material is preferably less dense than glass and metals and is selected to provide good mechanical strength and absence of brittleness. A polycarbonate is a suitable material for the wall 13.

A respective connector 14 is mounted in each end of the tube 13 for co-operation with adjacent ones of the bodies 10. The connector is in the form of a screw having a head 15 at one end and a male screw thread 16 adjacent to its other end. A shank of the screw extends through an aperture in an annular plug 17 permanently secured in the tube 13 immediately adjacent to one end thereof and the head 15 lies within the tube so that the screw 14 is prevented by the plug 17 from being withdrawn completely through the adjacent end of the tube. The screw can rotate relative to the tube.

On a part of the shank of the screw 14 which lies outside the tube 13, there is a tubular spacer 18 constrained by a key 19 to rotate with the screw 14 about the axis of the latter. The key is fixed in the screw and engages in a slot 20 formed in the spacer and extending along a part of the length of the latter, so that the spacer can undergo limited movement along the shank of the screw. It will be seen that the plug 17 is trapped between the head 15 and spacer 18 of the screw but there is freedom for limited axial movement of the screw relative to the tube 13.

When the tube 13 is to be assembled with the connecting body 10, the screw 14 is pushed into the tube 13 somewhat and the end of the tube is aligned with a screw threaded bore 21 in the connecting body with the spacer 18 interposed between the body and the plug 17. The tip of the screw is engaged in the bore 21 and the screw is rotated by means of the spacer 18 to draw the screw further out of the tube 13 and, when the head 15 has abutted the plug 17, to drawthetube 13towardsthe body 10 until the spacer 18 is trapped firmly between the connecting body and the plug 17. In this way, a rigid, releasable connection is established between the tube 13 and the body 10. A similar operation is performed to connect the tube 13 at its opposite end to a further one of the bodies 10.

In the completed frame, the element 11 has the function of a structural element, as do the elements 12. The element 11 supports at least some of the further elements, for example the element indicated at 1 2a in Figure 1. The frame may support some further body (not shown), in which case the element 11 may play a part in supporting the further body. It will be noted that the element 11 is supported by adjacent elements 12 via connecting bodies 10 and that the element 11 is so supported only at its ends in the manner hereinbefore described. If required, all of the elongate elements of the frame may have the form of the element 11. The novel element 11 can be used in the same manner as the known elements 12.

The tube 13 contains an electrically energisable light source 22. In the particular example illustrated, the light source is a known cold-cathode tube having an envelope 23 of fragile glass bearing on its internal surface a coating of a phosphor. The envelope may contain mercury vapour and an inert gas at low pressure.

The envelope 23 is supported by the tube 13 and is fixed with respect thereto by means of elastomeric supports 24 and 25 engaged with opposite end portions of the envelope. These supports are a press-fit within the tube 13 and have central aperturves to receive tails of the glass envelope. Through each tail, there extends a respective, flexible electrical conductor 26, 27 from a corresponding electrode within the envelope to a respective terminal 28, 29.

The envelope 23 is surrounded throughout its length by the wall 13 and is thereby protected against mechanical impact. The supports 24 and 25 are formed of material selected to reduce the transmission of shock from the tube 13 to the envelope 23.

It will be noted that the light source 22 is spaced considerablyfrom the ends of the tube 13.A terminal block 30 is permanently secured in each end portion of the tube 13 at a position spaced from the adjacent plug 17 and also spaced from the adjacent one of the supports 24 and 25. The terminal block is formed with a threaded bore 31, the axis of which is transverse to the length of the tube 13, and which extends from the middle of the block to the circumference of the block. An aperture 32 in the wall 13 is aligned with the bore 31 so that the bore has an open end at the circumference of the tube and a closed end adjacent to the longitudinal axis of the tube. The terminal 28 is disposed in the bore 31 adjacent to the closed end thereof and there is screwed into the bore a high tension electrical connector 33 having a terminal which abuts the terminal 28.An electrical conductor 34 extends from the abutting terminals along the interior of the connector 33 through the opening in the wall 13 of the tube to a high tension source of electrical energy (not shown). The connectors 33 may run along adjacent elongate elements 12.

It will be noted that the electrical connections with the light source 22 are maintained clear of the connectors 14, by means of which the mechanical connection between the tube 13 and connector bodies 10 is established. The screws 14 are preferably formed of metal but the terminal blocks 30 are preferably formed of electrically insulating plastics material. This ensures that the screws 14 and the tube 13 are electrically insulated from the light source.

It will be noted that there is an air gap between the envelope 23 and the wall 13 of the tube. This insulates the tube thermally from the light source and avoids the temperature of the tube 13 rising to that of the envelope 23 when the light source is energised.

The plugs 17 and terminal blocks 39 may be formed of the same material as the tube 13 and bonded therein by means of an adhesive. The tube 13 is conveniently cylindrical but could have a non-circular cross-sectional shape.

In the completed frame, there is no elongate element close to and parallel to the element 11.

Those elements 12 which are nearest to the element 11 are either inclined to the element 11 or are arranged in end-to-end relation therewith.

Claims (19)

1. A tube having a circumferential wall of robust, light-transmitting material, an electrically energisable light source disposed within the tube and electrical terminals connected with the light source.

2. A tube according to Claim 1 wherein both the light source and the terminals are spaced from ends of the tube.

3. A tube according to Claim 2 wherein the terminals are spaced from the light source and connected therewith by electrical conductors which are insulated from the tube.

4. Atube according to Claim 2 or Claim 3 wherein a terminal block is disposed within the tube at a position between the light source and one end of the tube, the block has a screw threaded bore arranged with its axis transverse to the length of the tube, one end of the bore is closed, an opening in the circumferential wall of the tubes is aligned with the other end of the bore and one of said terminals is disposed in the bore adjacent to the closed end thereof.

5. Atube according to any preceding claim wherein there is mounted in an end portion of the tube a connector suitable for use in connecting the tube with a further member.

6. A tube according to Claim 5 wherein the connector is trapped in the end portion of the tube with freedom for limited movement longitudinally of the tube.

7. A tube according to Claim 5 or Claim 6 wherein the connector is rotatable relative to the tube.

8. A tube according to any one of Claims 5,6 and 7 wherein the connector carries outside the tube a spacer for spacing the tube from a further member when the connector is used for connecting the tube to the further member.

9. A tube according to Claim 8 wherein the connector has a screw thread adjacent to its end remote from the tube and the spacer is keyed to the connector for rotation therewith.

10. Aframecomprising a plurality of connecting bodies and a plurality of elongate elements connected together by said bodies, wherein at least one of the elements is a tube, has a circumferential wall of light-transmitting material and contains an electrically energisable light source.

11. A frame according to Claim 10 wherein the tube is connected at its ends only with other elongate elements of the frame via respective ones of the connecting bodies.

12. A frame according to Claim 10 or Claim 11 wherein electrical conductors extend from the light source, through the circumferential wall of the tube to a source of electrical energy.

13. A frame according to any one of Claims 10 to 12 wherein the tube supports others of the elongate elements.

14. A frame according to any one of Claims 10 to 13 wherein the or each elongate element which is nearest the tube is either inclined to the tube or is arranged in end-to-end relation with the tube.

15. Atube according to any one of Claims 1 to 9 or a frame according to any one of Claims 10 to 14 wherein the light source is fixed in the tube.

16. A tube according to any one of Claims 1 to 9 or a frame according to any one of Claims 10 to 14 wherein the light source is supported by the tube.

17. Atube or a frame according to Claim 15 or Claim 16 wherein the light source is surrounded throughout its length by the circumferential wall of the tube.

18. A tube substantially as herein described with reference to and as shown in the accompanying drawing.

19. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawing.