GB2140147A

GB2140147A - Light bulbs and lighting systems

Info

Publication number: GB2140147A
Application number: GB08314073A
Authority: GB
Inventors: Simon Kelly; Dorian Kelly
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-05-20
Filing date: 1983-05-20
Publication date: 1984-11-21
Also published as: GB8314073D0

Abstract

A lighting system comprises a light source 26 having a lamp 34 directing light through a motor- driven colour wheel 36 into a plurality of optical fibre monofilaments 27, each of which leads to an individual bulb. The bulb comprises an envelope 10 having a screw-threaded base 11 in which is mounted a tube 15 supporting a sleeved optical fibre bundle 16. The sleeve 17 is stripped from the bundle within the envelope, and the individual fibres 18 are splayed apart. The tube 15 serves as a socket for the end of the monofilament 27, so permitting light to be fed into the bundle 16 from the monofilament 27. <IMAGE>

Description

SPECIFICATION Light bulbs and lighting systems This invention relates to a light bulb, and also to a lighting system employing a plurality of such light bulbs.

Many places of public entertainment require special lighting displays, so as to provide a particular atmosphere or ambience for visitors.

For example, night clubs and discotheques constantly strive to assemble light shows having unusual or spectacular lighting effects, which are often interconnected to an audio signal source. More recently, the extensive use of high-technology products, including microprocessors and lasers, has enabled very sophisticated lighting effects to be obtained.

However, the use of such technology has led to very high installation costs for lighting systems - a most important consideration when a place of entertainment such as a night club or discotheque may well wish to change its lighting system or light show maybe every year.

A particular problem which frequently is encountered when assembling a light show is that of being able to display various colours from a single location. This is often achieved by means of a 'colour wheel' which comprises a disc having translucent coloured sections mounted for rotation in front of a light source such that the source transmits light through only one section at a time of the disc. A motor is arranged to effect rotation of the disc, either continuously or intermittently as required, so that the light source apparently changes colour.In view of the complication of such an assembly, it is impractical for use where a large number of variable colour sources are required or where several variable colour sources are required in close proximity; a plurality of juxtaposed separate light bulbs must then be used, each coloured as appropriate and suitably switched to give the required effect. Such an installation inevitably leads to a most considerable amount of wiring so that the reliability of the installation may be poor and may present a fire hazard, quite apart from the high installation costs.

It is an object of this invention to provide a light bulb which may be used in a lighting system to enhance the effects obtainable thereby, which light bulb is nevertheless relatively cheap to manufacture and easy to install. It is a further object of the invention to provide a lighting system incorporating a plurality of such light bulbs, in which the colour of the light issuing from each bulb may if required be varied.

According to one aspect of this invention, there is provided a light bulb comprising a translucent envelope provided with a contiguous base portion, in which base portion there is arranged means supporting an optical fibre bundle which extends into the translucent envelope, the supporting means being adapted to permit the optical coupling of a light source to the end face of the bundle at the end thereof within the base portion, and the fibres at the other end of the bundle being splayed apart within the space enclosed by the envelope.

Most preferably, the translucent envelope is of circular cross-section and is generally spherical or mushroom-shaped, so that the envelope of the light bulb generally resembles that of a conventional incandescent filament light bulb. Moreoever, the base portion conveniently has a screw thread moulded or otherwise formed therein, to permit the mounting of the bulb in a holder generally similar to the holders used with conventional filament bulbs; the overall shape of the light bulb of this invention thus can closely resemble a conventional light bulb.

The light bulb of this invention may have the fibres splayed within the envelope so as to simulate the filament of an incandescent lamp. Thus, it is preferred for the tips of the fibres at said other end of the bundle to be splayed apart in such a way as to lie on a generally arcuate curve which is centred on the axis of the translucent envelope; consequently, when light issues from the tips of the fibres, the light will appear to be emanating from an incandescent filament. This effect is most apparent when the envelope is transparent, though the envelope may be frosted (i.e.

as with a 'pearl' lamp) or may be coloured.

As the light bulb runs 'cold' the envelope may be made from a wide range of materials.

It is however convenient for the envelope to be made of glass, which may be blown as with a conventional lamp, or which may otherwise be moulded to the required shape.

Alternatively, the envelope may be made from a plastics material such as a polycarbonate, which may be blown or moulded to the required shape. The base portion of the bulb may be integral with the envelope, especially where the envelope is made of a plastics material, or the base portion may be separately formed and attached to the main part of the bulb, for example by glueing or by chemical bonding. In such a case, the base portion may be metallic, as with a conventional lamp, or may be made of a plastics material.

In a case where a coloured light bulb is required, the material of the envelope may be coloured by an appropriate pigment during the manufacturing stage thereof, or the internal surface of the envelope may be coated with a colouring agent, following the manufacture of the envelope. However, the light bulb may be used to emit coloured light whilst having a clear envelope, by appropriate coupling of a coloured light source to the optical fibre bundle within the envelope.

With the light bulb of this invention, there is no need for the envelope to be hermetically sealed, unlike a conventional incandescent filament lamp. However, the bulb may contain an appropriate gas at a low pressure, the envelope then being hermetically sealed, such that when light of a suitable wavelength is coupled to the optical fibre bundle within the bulb, that low pressure gas fluoresces, the whole of the bulb then acting as a glowing light source.Appropriate selection of the gas, of the pressure of that gas within the envelope and of the wavelength of the light source coupled to the light bulb may cause the light bulb to glow with any one of a variety of colours-and light bulbs with different gases and/or gas pressures may all be coupled for example to a single ultra-violet light source, so as to give a display of a plurality of colours, all driven from one source.

The supporting means within the base portion preferably comprises a tubular member arranged centrally of the base portion and extending axially from the end of the base portion towards the envelope, the optical fibre bundle being fitted within the tubular member. By having the end of the tubular member exposed at the end of the base portion, this may directly serve as a socket to receive a source of light to issue from the fibres within the envelope. Though a holder for the light bulb could incorporate a suitable light source, it is preferred for the light source to be separate from the light bulb and its holder, but to be connected therewith by a length of an optical fibre bundle or of an optical fibre monofilament, which length of optical fibre is adapted to plug in to the socket defined by the end of the tubular member.

According to a second aspect of this invention, there is provided a lighting system comprising a plurality of light bulbs of this invention as described above, a like plurality of holders each adapted for mounting on a surface and arranged to carry a light bulb, a single light source remote from the holders, and a plurality of optical fibres each connected at one end to the light source so as to receive light therefrom and at its other end optically coupled to one light bulb respectively of the plurality thereof.

It will be appreciated that a lighting system of this invention as described above has considerable advantage as compared to a system having a similar number and corresponding array of individual incandescent filament lamps. The system of this invention requires only a single light source which provides the light which issues from each light bulb, and consequently the amount of wiring required as well as the complexity of the required switch gear is greatly reduced. This in turn leads to greater reliability, and a much reduced fire risk. By employing a single high intensity light source, each light bulb of this invention may still have a considerable brightness, but each light bulb runs cold, thus increasing yet further the safety of the installation.

The single light source of the installation of this invention may be arranged to allow the transmission of light of varying colour into the optical fibres leading to the individual light bulbs. For example, a motor-driven colour wheel may be disposed at the light source, so that in operation the colour of the light issuing from each light bulb varies with time. For a case where each light bulb has a clear transparent envelope and the tips of the fibres within in the envelope are arranged generally arcuately, this may give rise to a particularly attractive effect, in which it appears as though an incandescent filament lamp has its filament changing colours.

By way of example only, this invention will now be described in greater detail, reference being made to the accompanying drawings, in which: Figure 1 is a perspective view of a light bulb of this invention; Figure 2 is a perspective view but from below of the light bulb of Figure 1; and Figure 3 is a diagrammatic view of a part of a lighting installation of this invention.

Referring initially to Figures 1 and 2, there is shown a light bulb of this invention, which comprises a blown spherical glass envelope 10, attached by an adhesive to a moulded plastics material base portion 11. The plastics material from which the base portion is moulded is selected so as to be both relatively hard and easy to attach by an adhesive to the blown glass envelope 1 0. The base portion 11 has moulded in the external cylindrical surface thereof an Edison screw thread 12, of the form conventionally used with incandescent filament lamps, whereby the light bulb of this invention may be threaded into a modified form of conventional lamp holder.

The end face 1 3 of the base portion 11 has a plurality of ribs 14 moulded integrally therewith, which ribs support a tube 1 5 extending axially within the base portion 11. press4itted into that tube 1 5 is an optical fibre bundle 16, so as to extend from the base portion 11 into the envelope 10. The optical fibre bundle 1 6 comprises an outer substantially rigid sheath 1 7 within which is disposed a plurality of relatively fine glass fibre monofilaments 1 8.

The end portion of the outer sheath 1 7 within the envelope is stripped back from the fibres, and fibres are then splayed apart such that the tips 1 9 thereof lie on a generally arcuate curve, centred on the axis of the envelope 10. Such splaying of the fibres may for example be achieved by means of a headed pin, pressed axially into the sheath such that the head 20 of the pin causes the fibres to splay apart. An alternative technique may involve the use of a giue, placed at the end of the sheath and suitably disposed so as to maintain all of the fibres in the splayed apart condition illustrated in the drawings.

Light may optically be coupled to the optical fibre bundle within the envelope by means of a further length of optical fibre, such as that illustrated at 21 and having a plug portion 22 formed on the end thereof, which plug portion 22 may be received in the end of the tube 1 5. Light caused to travel along the optical fibre 21 will thus be received in the individual fibres of the bundle 1 6 within the light bulb, so as to issue out of the tips 1 8 of the fibres.

Figure 3 shows a part of a lighting installation arranged in accordance with this invention and used with light bulbs such as have been described above, referring to Figures 1 and 2. The various parts of the light bulb 25 shown in Figure 3 are identified with the same reference numerals as have been used in the foregoing description; these components will not be described again here.

The installation comprises a light source 26, a plurality of optical fibres (only one of which is shown in Figure 3, at 27) extending from the light source and arranged to received light therefrom, and a like plurality of bulb holders 28, each having a light bulb 25 fitted therewithin-and again only one holder 28 and bulb 25 are shown in the drawings. Each holder 28 is generally similar to that employed with a conventional incandescent filament bulb, except that the electrical connections are not fitted, and there is a central aperture 29 in the base 30 of the holder.

Each holder is also provided with a flange 31, permitting the mounting of the holder on a surface, for example by means of screw (not shown) extending through countersunk holes 32 provided in the flange. The connection of the optical fibre 27 may be made through the aperture 29 in the base 30 of the holder, in the manner described above with reference to Figures 1 and 2.

The light source 26 comprises a box 33 having mounted therewithin a high intensity lamp 34 (such as a filament lamp or a discharge-type lamp for very high intensity effects or stroboscopic effects) provided with a reflector 35 so as to ensure that a generally parallel beam is projected from the lamp. Also mounted within the box 27 is cooling fan assembly (not shown) In front of the lamp 33, there is mounted a colour wheel 36 having a plurality of differently coloured translucent sectors. The colour wheel is rotatable by means of a motor 37, connected to the wheel by means of a shaft 38. Behind the colour wheel 36, there is provided an aperture 39, into which light transmitted through the colour wheel passes to enter light into the end faces of the plurality of optical fibres leading to the light bulbs.

All of the fibres are bonded together within a screw-in connector 40, the fibre end faces being polished to be optically flat within the connector 40 which is received in a socket 41 disposed to surround the aperture 39.

In operation, the light source 26 may be mounted safely a some suitable point, whereas the holders 28 for the light bulbs 25 may be mounted wherever light is to issue for instance, across a ceiling. The optical fibres 27 are flexible, easy to install, and do not present any fire hazard; the laying of these fibres between the light source 26 and the holders 28 is thus particularly easy, as compared to conventional wiring. In operation, because of the provision of the motor driven colour wheel 36, each light bulb will appear to change colour, so leading to a particularly attractive light display.

Claims

1. A light bulb comprising a translucent envelope provided with a contiguous base portion, supporting means arranged within the base portion which means supports an optical fibre bundle extending into the translucent envelope, the supporting means being adapted to permit the optical coupling of a light source to the end face of the bundle at the end thereof within the base portion, and the fibres at the other end of the bundle being splayed apart within the space enclosed by the envelope.

2. A light bulb according to claim 1, wherein the translucent envelope is of circular cross-section and has a generally spherical or mushroom-shaped overall configuration.

3. A light bulb according to claim 1 or claim 2, wherein the base portion defines an external screw thread to permit the mounting of the bulb in a holder.

4. A light bulb according to any of the preceding claims, wherein the tips of the fibres at said other end of the bundle are splayed apart in such a way as to lie on a generally arcuate curve which is centred on the axis of the translucent envelope.

5. A light bulb according to any of the preceding claims, wherein the envelope is made of glass blown moulded to the required shape.

6. A light bulb according to any of claims 1 to 4, wherein the envelope is moulded from a plastics material.

7. A light bulb according to any of the preceding claims, wherein the base portion is separately formed from the envelope and is attached thereto by a bonding technique.

8. A light bulb according to any of the preceding claims, wherein the envelope is coloured, an appropriate pigment being incorporated in the material of the envelope during the manufacture.

9. A light bulb according to any of the preceding claims, wherein the envelope is hermetically sealed, and contains a gas at a sub-atmospheric pressure.

10. A light bulb according to any of the preceding claims wherein the supporting means within the base portion comprises a tubular member arranged centrally of the base portion and extending axially from the end of the base portion towards the envelope, the optical fibre bundle being fitted within the tubular member.

11. A light bulb according to claim 1 0, wherein the end of the tubular member is exposed at the end of the base portion, and serves as a socket to receive a source of light to issue from the fibres within the envelope.

1 2. A light bulb according to claim 1 and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

1 3. A lighting system comprising a plurality of light bulbs each according to any of claims 1 to 12, a like plurality of holders each adapted for mounting on a surface and arranged to carry a light bulb, a single light source remote from the holders, and a plurality of optical fibres each connected at one end to the light source soasto receive light therefrom and at its other end optically coupled to one light bulb respectively of the plurality thereof.

14. A lighting system according to claim 13, wherein the single light source is arranged to transmit light of varying colour into the optical fibres leading to the individual light bulbs.

1 5. A lighting system according to claim 14, wherein a motor-driven colour wheel is disposed at the light source, so that in operation the colour of the light issuing from each light bulb varies with time.

1 6. A lighting system according to claim 1 3 and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.