This invention relates to an optical fibre holder and output control system. As used herein, the term "optical fibre" includes elongate light guides which are circular, elliptical, rectangular, triangular, generally polygonal or of any other suitable shape in cross-section.

The use of optical fibres for channelling light to reguired points in lighting and display systems has a number of advantages: a single light source can illuminate multiple, separate locations; the heat generated by the electric light source can be kept away from the points of illumination; and the electrical fittings and connections for the light source can be isolated from the environment in which the illumination is required.

To date, optical fibres which are to be used in lighting or other display systems are generally collected into bundles of up to 12 fibres, the bundled ends of each of the fibres being presented to a light source when in use. .

The manufacture of the fibre bundles is time-consuming and costly and results in the breaking of a number of fibres. There are also a number of problems in the use of such fibre bundles as they either have to be manufactured with fibres of desired length or the fibres have to be cleaved to the desired length before use. Another serious problem with the use of such fibre bundles is that one lamp can only be used to illuminate up to 12 fibres and if any more outputs are required additional lamps are necessary.

The introduction of a fibre holder which would enable the use of more fibres with a single lamp and/or negate the requirement for the production of fibre bundles would constitute a considerable improvement.

US-A-474,087 discloses a fibre optic lighting system for boats, intended to provide illumination of a number of navigational lights from a central source. The system includes a cylindrical fibre holder which surrounds the light source, having mirror segments on an inner surface thereof. The design requires the fibre-receiving apertures of the holder to be drilled through the mirrors, which would be difficult to accomplish in practice. The design is generally complex and of doubtful practicability.

DE-A-2,625,174 and DE-A-2,835,666 each show seven-segment display elements wherein the segments are illuminated by light channelled via light guides from a remote source, the display output being controlled by a rotatable mask located between the light source and the ends of the light guides. EP-A-0,129,662 shows a control knob wherein light guides and a movable mask are used to illuminate a scale indicating the setting

of the knob. None of these devices lend themselves towards use in a lighting unit of the type contemplated in the present invention.

It is an object of the present invention to provide an optical fibre holder, and a lighting unit incorporating such a holder, allowing a relatively large number of optical fibres to be illuminated by a single light source, which is comparatively simple and inexpensive to manufacture and which is flexible in use, being readily adapted to suit particular requirements as regards the nature of the light output required and the number and type of optical fibres to be employed.

According to a first aspect of the present invention there is provided an optical fibre holder comprising a housing having a plurality of apertures adapted to receive optical fibres and being adapted to enclose a light source, said housing being generally cylindrical, said apertures being distributed over the surface thereof, and said housing including a plurality of annular sections secured together to form a cylindrical body.

Preferably, said fibre receiving apertures are formed at the interfaces between adjacent annular sections.

Preferably also, at least one annular face of each annular section has a plurality of radially extending grooves formed therein, said grooves defining said apertures when said annular surface is in abutment with an adjoining annular section.

Most preferably, both annular surfaces of each annular section have a plurality of radially extending grooves

formed therein, said apertures being defined by the alignment of the grooves of two adjoining annular sections.

Preferably also, each groove formed in one surface of each annular section is located between a pair of adjacent grooves on the opposite surface of the section, such that when a plurality of sections are assembled together the housing includes a number of circumferential rows of apertures wherein the apertures of each row are angularly staggered relative to the apertures of the adjacent row.

Preferably also, one annular surface of each section has a raised shoulder formed around the circumference thereof and the opposite annular surface has a recessed shoulder formed around the circumference thereof, such that when two sections are assembled together the raised shoulder of one section engages the recessed shoulder of the other section so as to maintain the sections in axial alignment.

Preferably also, said housing further includes at least one generally cylindrical spacer element secured to at least one end of the cylinder formed by said plurality of annular sections.

Preferably also, said annular sections are secured together and said optical fibres are secured in said apertures by means of a suitable adhesive.

Each of the apertures may receive a single optical fibre or a bundle of fibres.

Each of the fibres may be of any desired length.

According to a second aspect of the present invention there is provided a lighting unit including an optical fibre holder, as claimed in any preceding Claim, secured to a base member, said base member including a light source adapted to extend inside the housing of said optical fibre holder.

Preferably, said light source comprises an electric light bulb mounted in a bulb holder located in said base member.

Preferably also, the lighting unit further includes a cooling fan adapted to direct a flow of air past said light source and through the interior of said housing.

Preferably also, the lighting unit further includes a substantially transparent cylinder adapted to be received by the housing of said optical fibre holder, the cylinder having areas with different optical transmission characteristics, the said areas blocking the path of the light to selected apertures in the housing and/or filtering the desired wavelengths before transmitting the light to selected apertures.

Preferably also, the cylinder is coated with an opaque material in a pattern which blocks light to the selected apertures.

Preferably also, the cylinder is coated with an opaque material in a pattern which blocks light to the required apertures.

Preferably also, different patterns may be provided on different cylinders to allow light to be passed to different apertures..

Preferably also, the lighting unit further includes means for rotating said substantially transparent cylinder relative to said housing.

Preferably also, said substantially transparent cylinder is rotated by drive means engaging the surface of the cylinder adjacent one end thereof.

Preferably also, said cylinder is provided with a toothed flange extending around its surface at said one end, and said drive means comprises a cog wheel engaging said flange and driven by an electric motor located in the base member of the unit.

Preferably also, said electric motor is a stepper-motor.

Preferably also, different partially opaque materials are used to allow a lower intensity of light to be transmitted to selected apertures.

Different partially opaque materials may also be used to allow a lower intensity of light to an aperture if required.

Colour filters may be used to transmit only a specific wavelength band to particular apertures when required.

The output end of the fibres attached to the apertures may be arranged in a matrix such that the light emitted by specific fibres may produce patterns or words.

Alternatively, the output ends of individual fibres may be positioned to illuminate at required locations.

Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings in which:-

Fig. 1 is a schematic side view of a lighting unit incorporating an optical fibre holder in accordance with the present invention, attached to a lamp housing and fan; Fig. 2 is a partial sectional view of the unit of Fig. 1; Figs. 3(a), 3(b) and 3(c) are, respectively, front and left and right hand elevational views of the optical fibre holder of the unit of Figs. 1 and 2; Figs. 4(a), 4(b), 4(c) and 4(d) are, respectively, schematic end elevations and side elevations of a cylinder and a rotary motor spindle for use in the lighting unit of Figs. 1 and 2; Figs. 5(a), 5(b) and 5(c) are, respectively, a left hand and a right hand end elevation and a sectional side elevation of the lamp holder of Fig. 1; Fig. 6 is a schematic side view, partly in section and partly exploded, of a lighting unit incorporating an optical fibre holder of a second, particularly preferred embodiment of the invention; Figs. 7(a), 7(b) and 7(c) are, respectively, top, bottom and side views of one of a plurality of annular sections which make up the optical fibre holder of the embodiment of Fig. 6; Fig. 7(d) is an enlarged, fragmentary, sectional side view of two of the annular sections of Fig. 6 in abutment; Figs. 8(a), 8(b) and 8(c) are, respectively, top, bottom and sectional side views of a base member

of the lighting unit of Fig. 6; Fig. 9 is a schematic perspective view of the unit of Fig. 6; and Fig. 10 is a schematic illustration of a matrix of optical fibre-ends.

Referring now to the drawings. Figs. 1 and 2 illustrate a first lighting unit incorporating an optical fibre holder 1, embodying the invention. The holder 1 is generally cylindrical, and has a plurality of apertures (omitted from Figs. 1 and 2 for clarity) distributed over its surface. Each aperture is adapted to receive a single optical fibre (not shown) or a bundle of fibres (not shown) . The holder 1 is mounted on a base comprising a lamp housing 6 and a fan housing 7. The lamp housing encloses a light fitting (not shown) mounting a bulb (not shown) which extends into the interior of the fibre holder 1 to illuminate the ends of the fibres located in the holder apertures. The fan housing 7 encloses a cooling fan (not shown) which directs a flow of air through the interiors of the lamp housing 6 and the fibre holder 1.

Figs. 3(a), 3(b) and 3(c) illustrate the fibre holder 1 in greater detail. The holder 1 comprises a central cylindrical portion 8 with square mounting flanges 9 at either end. The flanges 9 are provided with through-bores 10 by means of which the holder 1, may be attached to the lamp housing 6 or otherwise mounted as required in any particular application.

The apertures 2, into which the optical fibres (not shown) are fitted are arranged in a series of sets of apertures spaced around the circumference of the cylinder 8, a plurality of such sets being spaced along

the length thereof. As illustrated, each set comprises only four apertures 2 for the sake of clarity. In practice there would be a greater number of apertures 1 in each set, typically sixteen to twenty.

If the cylinder 8 were to be formed in a single piece, then it would be necessary to drill or otherwise form each of the apertures 2 individually, which would be relatively difficult and time consuming given that each holder might have over one hundred (typically up to one hundred and forty) apertures. In accordance with the invention, the cylinder 8 is made up of a number of ring-shaped annular sections 11, with the apertures 2 formed at the interfaces between adjacent sections 11 by radially extending grooves in the annular surfaces of each section. Such grooves can be formed by moulding or pressing during the manufacture of the annular sections 11, obviating the need for time consuming drilling operations. The grooves can also be readily formed with any required cross-sectional shape besides the circular form illustrated to suit optical fibres of different shapes. Large numbers of polygonal apertures would be extremely difficult to form in a cylindrical body otherwise.

Referring again to Figs 1 and 2, the light output from the optical fibres located in the holder 1 may be controlled and varied by means of a substantially transparent, rotatable, cylinder 3 which extends along the length of the holder 1 between the interior surface thereof and the light bulb (not shown) which would extend along its central axis in use. The cylinder 3 is supported and rotated by means of a spindle element 5 which engages one end of the cylinder and is secured to the shaft of an electric motor 4 co-axially with the

cylinder 3 and housing 1.

The cylinder 3 has areas with different optical transmission characteristics which affect the output of the light through the cylinder 3 to the apertures 2 in the housing 1.

The cylinder 3 may be coated with an opaque material in a pattern which blocks light to the required apertures 2, different cylinders 3 having different patterns.

Alternatively, colour filter or partially opaque materials may be utilised to filter out unrequired colours of light to the apertures 2 or to allow lower intensities of light to the apertures 2, respectively.

Rotation of the glass cylinder 3 allows sequential alteration of the optical output to the apertures 2.

When in use the output ends of the fibres, attached to the apertures 2, may be arranged in a grid patterns such that the light emitted by the specific fibres may produce pattern or words on the grid.

The large number of fibres which may be attached to one housing 1 allow the patterns and words produced to be very detailed. The use of colour filters and partially opaque materials on the cylinder enables the production of coloured and shaded pictures at the output.

Alternatively the output ends of the fibres may be arranged to illuminate a large area or multiple separate locations, different areas being coloured differently and illuminated to different intensities depending on the pattern on the cylinder 3.

The rotation of the cylinder 3 enables scrolling of words and patterns on the grid and interesting optical effects in general.

The rotatable cylinder 3 and motor 4 can simply be omitted if the unit is only required to provide static lighting.

Figs. 5(a) to 5(c) illustrate the lamp housing 6, which comprises a generally rectangular champer, open at either end and having a socket 12 located in the centre thereof by means of webs 13. The socket 12 may be configured to receive any suitable type of electric light fitting.

Figs 6 to 9 illustrate a second, particularly preferred embodiment of a lighting unit incorporating an optical fibre holder in accordance with the invention.

The unit again comprises a base consisting of a fan housing 20, a lamp housing 21, and an optical fibre holder assembled from a plurality of annular sections 22.

In this case the grooves 24 formed on either annular surface 25 (shown cross-hatched in Figs. 7(a) and 7(b)) of each annular section 22 are angularly displaced from one another so that each groove on one face lies between a pair of adjacent grooves on the opposite face, allowing the density of the apertures defined by the aligned grooves 24 in the assembled fibre holder to be maximised. Each section 22 also includes a raised circumferential shoulder 26 around the periphery of one annular surface and a corresponding recessed shoulder 27 around the periphery of the opposite surface. The

raised and recessed shoulders 26 and 27 of adjacent sections 22(a) and 22(b) co-operate when assembled, as seen in the enlarged, fragmentary, sectional view of Fig. 7(d), to maintain the sections in axial alignment. other configurations of co-operating projections and recesses might also be used for this purpose.

The fibre holder further includes a spacer ring 28 which can be attached to one or both ends of the cylinder formed by the annular sections 22. The sections 22 of the holder and spacer rings 28 may be secured together, and the fibres (not shown) secured in the holder apertures, by epoxy adhesives or by any other suitable means.

The lamp housing 21 comprises a generally square casing, open at one side adjacent the fan housing 20 and having a circular aperture 29 formed in the middle of the opposite face 30 therefrom. The light fitting 31 is mounted centrally in a plate 32 located parallel to and spaced from the face 30 of the lamp housing 21 on the interior thereof. The plate 32 is secured to the housing by means of screws or the like (not shown) extending through apertures 33 formed in the face 31 of the housing 21, tubular spacer elements 34 and apertures 35 in the plate 32.

The bulb 36, when mounted in the light fitting 31, extends along the central axis of the fibre holder. The bulb 36 might suitably be a 500 watt, 2900 lampen, halogen bulb. The size and power of the bulb 36 (or, more particularly, the longitudinal length of the filament 37) may be selected to suit the length of the fibre holder.

The fan housing 20 is secured to the open side of the lamp housing 21 by means of screws or the like (not shown) , and may be provided with legs or locating pegs 38. The unit may be free-standing or may be affixed by any suitable means to any horizontal or vertical surface.

As in the previous example, the unit may optionally include a rotatable output control tube 39 driven by a motor 40. In this case the tube 39 includes a toothed flange 41 extending around the circumference of one end thereof, the motor 40 being mounted on the plate 32 and having a cog 42 located on its shaft which engages the toothed flange 41 to rotate the tube 39. The tube 39 extends through the aperture 29 of the lamp housing 21 between the inner surface of the fibre holder and the bulb 36, and is retained in position by the location of the flange 41 between the face 30 of the lamp housing 21 and the plate 32. This simple arrangement will be adequate for most purposes, but a more sophisticated bearing arrangement may be incorporated if necessary or desirable.

The motor 40 is preferably a stepper-motor, allowing the movement of the tube 39 to be placed under direct digital control.

As before, the fan housing 20 encloses a cooling fan (not shown) adapted to direct air through the interior of the lamp housing 21 and fibre holder. The plate 32 may be provided with suitable apertures to facilitate the passage of the cooling air.

Fig. 9 is a schematic perspective view of the unit, showing a number of optical fibres 50 extending

outwardly from the apertures 51 formed in the fibre holder 52. The fibres 50 can be of any desired length (practically, up to 5-8 metres with a 500 watt halogen bulb) , allowing the light from the bulb to be channelled to the desired location. The unit may provide multiple spot-lighting in a room, provide illumination of large areas indoors, outdoors or in hazardous environments, provide decorative illumination, or control a graphical and/or alpha-numeric display. Fig. 10 provides a simple illustration of a matrix of fibre ends, partially illuminated and partially masked to create a letter 'A' . New optical fibre materials will allow the practical length of the fibres to be increased significantly, broadening the possible applications of the unit. The output ends of the fibres may be connected to any suitable optical "terminals" for modifying the shape of the output end, focussing, diffusing or otherwise modifying the output light, etc. according to the particular application of the invention.

The apertures 51 may each receive a single fibre on a bundle of fine fibres, and a single holder 52 may include apertures of different shapes and sizes accommodating both single fibres and bundles of fibres of similarly varying shapes and sizes. The apertures might typically range from 1 to 8 mm. The high density of the fibres on the holder surface also means that little of the source light is lost. The assembly of the optical fibre holder from annular sections, besides simplifying manufacture, enables the size of the holder to be varied as desired, and allows combinations of different shapes and sizes of apertures to be incorporated in a single holder using a range of

"standard" components. The holder sections, housings, etc. can be moulded, pressed or cast from any appropriate materials.

Modifications and improvements may be incorporated without departing from the scope of the invention.