GB2474460A

GB2474460A - Lighting system for selectively coupling a light source to light outputs

Info

Publication number: GB2474460A
Application number: GB0917994A
Authority: GB
Inventors: Jonathan Heffernan; Glyn Barry Pryce-Jones; Stewart Edward Hooper; Victoria Broadley
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2009-10-14
Filing date: 2009-10-14
Publication date: 2011-04-20
Also published as: GB0917994D0

Abstract

A remote source lighting system has a light source 1, light outputs, such as optic fibres 5 and a single coupler 3 for selectively coupling light from the light source towards one or more desired ones of the light outputs. The coupler may, for example, be a moveable/re-orientatable mirror that generates beams 4 from the incident light beam 2 from the light source 1, with the coupling of light towards the light outputs being dependent on the position/orientation of the mirror 3. The system can provide independently controllable light outputs from a central light source, while requiring only a single coupler 3. Driver circuits 8 can control the intensity of the light and the orirntation of the mirror. The lighting system may be used in a vehicle for taillights and headlights or a building.

Description

Light Bus

Field of the Invention

The invention relates to the centralised distribution of light for remote source lighting and in particular the use of laser diode lighting as the source of illumination. The invention may be applied to, for example, a vehicle lighting system, domestic lighting or building lighting.

Background of the Invention

Growing concerns for the environment and the depletion of fossil fuels has lead to a concerted effort by scientists to reduce energy consumption in every aspect of modern living. One area where significant energy efficiency savings can be made is in the field of lighting for commercial, domestic and automotive applications. Most homes still use a combination of traditional incandescent bulbs, halogen bulbs and fluorescent tube lighting. Halogen bulbs are popular due to their high brightness and long lifetimes of 2000- 35000hrs. However, both incandescent and halogen bulbs are hugely inefficient yielding luminous efficiencies of l7Lm/W and 2OLmIW respectively.

But both provide compact sources which are simple to replace. Compact fluorescent lamps are widely used in offices due to their superior efficiency of 100LmIW and their long lifetimes of up to l5000hrs. However, these lamps are bulky and contain high pressure gases and mercury, posing risks to the user and also environmental concerns for safe disposal. Fluorescent lamps also exhibit slow turn on especially in cold conditions, making them unsuitable for use in automobiles. Xenon arc lamps are now widely used in car headlights, due to their superior brightness over incandescent and halogen bulbs. But they are still fairly inefficient with an efficiency of 3OLm/W.

Solid state lighting has been tipped as the energy efficient solution to all domestic and commercial lighting needs. Research into LED (light-emitting diode) lighting has yielded massive improvements in LED luminescence, with current state of the art white LEDs yielding luminous efficiencies of 8OLmIW.

However, the inferior brightness and high cost of LEDs compared to existing technologies has meant that LED lighting has been limited mainly to signage and decorative applications. LED headlamps are available but large arrays of LED are required to match the brightness of existing Xenon headlamps, resulting in a huge amount of heat generated at the LED chip.

One of the main disadvantages of all of the aforementioned lighting systems is that bulbs and lamps must be replaced individually. In some applications such as the lighting of tall buildings, shopping malls or swimming pools, access to individual light bulbs is problematic. Remote source lighting systems provide a solution to avoid the cost and time required to maintain lighting systems such as these. Commercially available systems use high power discharge lamps as a central light source, which is located in an easy maintenance location. Light from the source is then piped around the building to remote locations using light pipes or optical fibers. Remote lighting systems are Electromagnetic Interference Free (hereafter referred to as EMI free) as the fibers carry only photons and no current, making them ideally suited for use in electrically noisy environments. The use of optical fibers rather than copper wiring also makes remote lighting systems ideally suited to use in high moisture environments, such as lighting for swimming pools, saunas and shower enclosures. In addition remote source lighting provides cold light at its output, as all heat generated by the lamp is contained at the source leading to no/minimal heating at the output. Remote source lighting systems are currently used to light tall buildings, swimming pools and large enclosed spaces, such as shopping malls. However, remote lighting systems are not widely used in homes or in cars, as they are bulky and fairly inefficient as a lot of the light is lost in the focusing the lamp light into the different light channels.

These systems are also fairly heavy and bulky making them unsuitable in particular for use in cars, where space and weight are at a premium for manufacturers aiming to reduce fuel consumption and costs. In addition, once a current remote lighting system is installed it is difficult to add additional outputs, making them inflexible to upgrades and alterations. It is the purpose of this invention to provide an improved remote lighting system which is compact, energy efficient whilst also providing a much wider flexibility and adaptability of use.

Acknowledciement of the prior art

Commercial remote source lighting systems using high intensity discharge lamps are widely available from companies such as RSLfiber systems and Energy Focus Inc. Although remote source lighting systems are not widely used in cars, some efforts have been made to improve their suitability for use in automobiles. US5713654 describes an addressable laser vehicle lighting system, where a plurality of laser diodes is centrally located on a vehicle.

Each laser diode is individually coupled into an optical fiber for the delivery of light to various optical loads around the vehicle. The system provides individually addressable laser diodes, but there still remains the disadvantage that each optical load has an associated light source, which must be separately replaced should it fail.

US5365413 describes a vehicle lighting system whereby, as shown in figure 1, a light source or sources 34 are located on a central axle 31 around which a light guide or array of light guides 37 is distributed on a collar 36. The axle 31 and hence the light source(s) 34 are rotated by a drive 32. Light from the or each light source 34 is focused by a reflector 33 to produce, at the collar, a "spot" 38 that is comparable in size to the input face of one of the light guides 37. The rotating central light source(s) 34 operate in pulsed mode as controlled by external circuitry such that individual light guides 37 may be illuminated when the light source 34, or one of the light sources 34, and light guide in question are aligned. This invention provides the user with ability to control the illumination of a plurality of light outputs. This invention allows individual light outputs to be controlled independently whilst also retaining the simplified maintenance costs of a single remote light source. However due to the rotating nature of the light source, the invention can not allow any one output to be continuously illuminated and also limits the maximum output power from the system by constraining the number of light sources that could be fitted to the rotating axle. The rotating light source is also less stable than a stationary light source, which when used with a moving mirror is more suited for operation in a high vibration environment such as a car.

EP0613981A1 describes a laser system with fiber optic distribution for motorway signalling in fog. The invention includes several light sources, positioned at the side of the road, which are each coupled into an optical fiber or fiber bundle. The fiber bundles are distributed to a suitable number of lighting points along the motorway. The invention allows for multiple light outputs from a single light source. However, individual light outputs from one light source are not separately controllable. The light sources and light outputs are permanently connected, making the system inflexible to changes in use.

US5422792 provides an illumination device for vehicles, which includes at least one light source and a plurality of light conductors which are connected to a plurality of light distribution outputs. The light output from each light conductor is controlled using a screening device positioned in the light path of each conductor. The light source remains on at all times, so in order to switch off an individual light output the screening device associated with that light output is repositioned to reflect the light beam to a different light conductor.

The system requires a screening device for each light output making it bulky for systems including many light output channels. In addition the system of US5422792 cannot control the light brightness level at each output point to an intermediate level and can provide only fully on or fully off outputs.

A light distribution system for cars using a ring of light pipes arranged around the light source is described in US5452186. The first ends of the light pipes are shaped so that in combination they form a ring-shaped pattern for optimising the coupling of light from the source into the light pipes. The second ends of the light pipes are distributed around the car to various lighting outlets. This invention is limited to the simultaneous illumination of an array of light pipes. There is no opportunity for individual switching of the light outputs.

In the last decade the use of fiber optics by the telecommunications industry to transfer data has become increasingly widespread. Telecommunications systems are similar in principle to remote source lighting systems, involving a laser light source coupled to a fiber or fiber array, which is routed to a detector at the end of each fiber. The optical data signals are routed to their destination or around faults in the line using switches. US patent 6396976 describes an all-optical switch using a micromachined mirror (MEMS) array, also shown in figure 2 (taken from US 6396976). The invention provides a two dimensional MEMS array 40 which is positioned at the intersection of input optical paths 44 and output optical paths 46 where the mirrors are angled at 45 degrees to the light paths. Each mirror element may be individually tilted by 90 deg in to the plane of the optical path to deflect the light beam from the input path associated with the mirror element to the required output path. In this configuration the optical signal may be routed to one output fibre of an array of output fibers. This MEMS system is limited to the supply of light from one fiber to another fiber at one time. For data a communication system simultaneous illumination of multiple outputs using a single input is not desirable, but for a lighting system would offer significant energy and space savings.

Concept of the invention A first aspect of the present invention provides a remote source lighting system, the system comprising: a light source; a plurality of light outputs; and a single coupler for selectively coupling light from the light source towards one or more desired ones of the light outputs. The lighting system of the invention allows multiple, independently-controllable outputs to be provided using a central light source (so eliminating the need for each optical load to have a separate light source), without the need for an individual screening device for every light output as required in US5422792.

The coupler may, in use, split light from the light source into a plurality of light beams, and selectively couple the light beams to respective ones of the light outputs.

The system may comprise a plurality of light guides, each light guide directing light, in use, to a respective one of the light outputs; and the coupler may be adapted to selectively couple light from the light source into one or more selected ones of the light guides. The light guides may for example be optical fibres or bundles of optical fibres.

The coupler may comprise single reflector unit. This is a convenient way of selectively coupling light towards one or more desired light outputs.

The coupler may comprise a moveable and/or re-orientable reflector. This provides a simple but effective coupler for selectively coupling light towards one or more desired ones of the light outputs. The reflector may have multiple reflecting surfaces adapted, for at least one position/orientation of the reflector, to reflect light from the light source in multiple different directions.

Alternatively, it may have a single reflecting surface.

The system may further comprise a second plurality of light outputs; and a second single coupler for selectively coupling light from the light source towards one or more desired ones of the second plurality of light outputs.

This allows the number of possible light outputs to be increased.

The system may comprise a first driver circuit for controlling the position and/or orientation of the reflector.

The driver circuit may determine the position and/or orientation of the reflector as well as controlling movement of the reflector. Alternatively, the system may comprise a sensor for determining the position and/or orientation of the reflector. For example, a photodiode may be used to monitor the position of one beam generated by the reflector.

The first driver circuit may be adapted to control the position and/or orientation of the reflector on the basis of a user input. Additionally or alternatively, it may control the position and/or orientation of the reflector on the basis of an input from a sensor.

The system may comprise a second driver circuit for controlling the light output from the light source. This allows the light source to be controlled to emit light at an intermediate intensity, and so allows the intensity at a selected light output to have an intermediate level. There may be a combined driver circuit that controls both the position and/or orientation of the reflector and the light output from the light source (ie, that acts as both the first driver circuit and the second driver circuit), or the first driver circuit may be separate from the second driver circuit.

The light source may comprise an array of illumination sources. This provides redundancy, and ensures that the system may continue to operate if one illumination source fails.

The light source may comprise two or more independently controllable illumination sources. For example, the light source may have independently controllable illumination sources that emit light of different wavelengths (eg, red, green and blue light sources), to allow light of a desired colour to be obtained at a selected output.

The system may further comprise a common light guide having a plurality of light outputs. For example, the common light guide may deliver light to a series of low-brightness optical loads while other light guides deliver light to respective high-brightness optical loads.

A second aspect of the invention provides a vehicle comprising a remote source lighting system of the first aspect.

A third aspect of the invention provides a building comprising a remote source lighting system of the first aspect.

The present invention is a remote source lighting system comprising, in one embodiment, a central light source and a movable/re-orientable mirror which creates a plurality of light beams from that light source and couples these light beams to an array of optical fibers. The illumination of individual optical fibers is controlled by electrical driver circuitry which is connected to the light source and the movable/re-orientable mirror. Complete control over the output from each optical fiber is afforded by the driver circuitry, allowing all fiber outputs to be simultaneously on or off or individual fiber outputs to be switched. The brightness at each fiber output is also independently controlled by the circuitry. The central light source may comprise a single laser diode or laser diode array, an LED array, superluminescent diode array, a fiber laser or fiber laser array or any other high brightness light source. The light beam from each light source may be reflected by the mirror to generate one or more secondary light beams. The light source or sources are contained within a single unit which is conveniently located remotely from the output points of the optical fibers, for ease of maintenance and also to enable central heat management of the sources. The movable/re-orientable mirror may be a micro machined mirror (MEM5 mirror), a rotating galvanometer or a rotating polygon mirror or any other movable/re-orientable mirror.

Advantacies of the invention The invention provides a remote lighting system which is more compact than existing remote lighting systems, due to the use of a single light source unit and a small movable/re-orientable mirror, avoiding the need for complex and bulky optical components.

The location of the compact light source unit may be chosen to enable easy maintenance access and also reduced maintenance costs. The need to replace dozens of individual bulbs is also avoided with this system. The compact light source and use of light-weight optical fibers make the unit particularly suited for use in cars, where space is limited and every gramme of extra weight directly affects the fuel efficiency of the car. The use of a central light source also simplifies the heat management of the system, where the light sources can be located away from large heat sources and also one central heat sink or cooler may be employed to regulate the temperature of the light sources themselves. The primary advantage of this invention over the prior art is the flexibility and functionality of the lighting system. The use of the movable/re-orientable mirror enables complete independent control of all the optical fiber outputs including the ability to adjust the brightness in each fiber independently. The invention is also very flexible to the addition of extra optical fiber outputs without the need to change or modify the system hardware. Redundant fibres built into the system, could be brought into use with simple re-programming of the driver circuitry. This feature makes the invention ideally suited for use as a lighting system for homes and buildings.

The invention also offers a lighting system which delivers cold lighting at the output which is EMI free.

Description of the drawings

Figure 1 is a schematic of rotating light sources within a collar on which are arranged an array of optical fibers in the prior art.

Figure 2 is a schematic of a 2D micro-machined optical switch in the prior art.

Figure 3 is a schematic of the constituents of the present invention.

Figure 4 is a schematic of the constituents of the present invention including the provision of a photodiode and heat sink.

Figure 5 is a side view of a vehicle containing a light bus according the first embodiment of the present invention.

Figure 6 is a plan view of a vehicle containing a light bus according to the first embodiment of the invention Figure 7 is a schematic of the light bus input and outputs according to the first embodiment of the invention.

Figure 8 is side view of a vehicle containing a light bus according to the second embodiment of the invention.

Figure 9 is a plan view of a vehicle containing a light bus according to the second embodiment of the invention.

Figure 10 is a sectional view of a house containing a light bus according to the third embodiment of the invention.

Figure 11 is a schematic view of a light bus according to a further embodiment of the invention.

Description of the embodiments

Preferred embodiments of the present invention will be described, by way of example, with reference to the drawings.

The principal constituents of a lighting system of the present invention are shown in Figure 3. The light bus, 9 includes a central light source 1, which produces a light beam or light beams, 2 that illuminate a coupler 3 that couples light from the light source into selected ones of a plurality of optical fibres 5 and hence couples light from the light source to selected outputs (i.e., to the outputs of the selected optical fibres).

The invention uses a single coupler to couple light from the light source 1 into selected ones of the optical fibres 5. In a preferred embodiment the coupler is a single reflector unit, that is a reflector unit that can selectively generate and/or selectively direct light beams 4 from the incident light 2 received from the light source. This provides a convenient and easy to implement coupler.

The reflector unit may be a reflector (mirror) 3 that may be moved and/or re-oriented. The mirror may have a single reflecting surface, or it may have a plurality of reflecting surfaces that have different orientations to one another.

In the embodiment shown in figure 3 the mirror 3 comprises a plurality of mirror facets, which have different orientations to one another. The moving mirror, 3 thus generates a plurality of light beams, 4 from each incident beam, 2 which are directed by the mirror onto an array of optical fibers, 5. The light beams 4 generated by the mirror 3 are coupled into selected ones of the optical fibres 5, dependent on the position and/or orientation of the mirror 3.

Thus, by suitably controlling the position and/or orientation of the mirror 3 it is possible selectively to couple light beams 4 into none, some, or all of the optical fibres 5. The invention thus makes it possible to obtain a plurality of independently controllable light outputs (ie the outputs of the optical fibres 5) from a central light source, while using only a single coupler (ie, the mirror 3).

The light source, I and the moving mirror, 3 are both connected to external driver circuitry, 8. The external driver circuitry, 8 controls the movement of the mirror, 3 and switches the light source 1, such that the reflected light beams 4 may be addressed to desired individual optical fibers, 5. The light source, 1 may comprise a single laser diode or laser diode array, a superbright LED array, a superluminescent source or any other high brightness light source.

Preferably the light source, 1 comprises a laser diode array to allow for redundancy in case of the failure of one or more laser diodes.

The light bus may constitute a single moving mirror or multiple moving mirrors. The light bus may constitute between 1 and 10 moving mirrors.

Preferably the light bus would contain between two and five moving mirrors, 3.

As noted above, the/each moving mirror may have one reflective surface or may have more than one reflective surface (or, where two or more mirrors are present, at least one may have one reflective surface and at least one may have more than one reflective surface.) Figure 11 is a schematic view of a light bus of the invention that contains two mirrors 3, 3'. The light bus 9 of figure 11 is based on the light bus of figure 3 and contains, as for the embodiment of figure 3, a light source 1, a first plurality of optical fibres 5, and a first coupler (in this embodiment a moving/re-orientable mirror) 3 for selectively coupling light 2 from the light source into one or more of the first plurality of optical fibres 5. The light bus 9 of figure 11 further includes a second plurality of optical fibres 5', and a second coupler (in this embodiment a second moving/re-orientable mirror) 3' for selectively coupling light 2' from the light source into one or more of the second plurality of optical fibres 5. This allows the light bus to provide a greater number of possible light outputs, as the light bus of figure 11 can include a greater number of optical fibres than can the light bus of figure 3.

(In a practical implementation of the invention there may be a practical limit on the number of optical fibres that can be disposed around, and selectively illuminated by, a mirror 3, 3'.) Alternatively, if an optical fibre from the first plurality of optical fibres 5 and an optical fibre from the second plurality of optical fibres 5' should have a common output, this would provide a degree of redundancy against failure of one of the mirrors 3, 3'.

In Figure lithe second plurality of optical fibres 5' are shown as similar to the first plurality of optical fibres 5', and the second coupler 3' is shown as similar to the first coupler 3. The embodiment of figure Ii is not however limited to this and the second plurality of optical fibres 5' may differ from the first plurality of optical fibres 5', and/or the second coupler 3' may differ from the first coupler 3.

Figure ii shows the first and second coupler 3, 3' as controlled by common driver circuits. The embodiment of figure ii is not however limited to this and the first and second coupler 3, 3' may be controlled by separate driver circuits.

Although the embodiments of figures 3 and ii are described above with reference to a coupler comprising a mirror having a plurality of facets, the invention is not limited to this. The moving mirror or mirrors, 3 may constitute one or more of the following, micro machined mirror (MEM5) mirrors, polygon mirrors (e.g., rotating polygon mirrors), galvanometers or any other moving/re-orientable mirrors. Preferably the light bus, 9 contains at least one galvanometer scanning mirror as the moving mirror 3. A galvanometer scanning mirror is a high performance rotary mirror. It consists of a motor section for electrical signal input, a high precision position detector and a mirror section. An electrical signal to the motor (i.e. dc current) rotates the mirror by an angle proportional to the input signal. A galvanometer scanning mirror has a very fast response time (typically O.lms) and accurate mirror response is possible. Suitable galvanometer scanning mirrors are manufactured by, for example, Nutfield Technology, mc, for example their QuantunScan-7 or the QuantunScan-lO mirrors. A planar moving mirror is another example of a mirror that may be used in the invention. A planar mirror can generate beams in different directions simply by moving/re-orienting, i.e. it generates a plurality of light beams by moving/re-orienting thus allowing selective coupling of light from a light source to outputs (although of course, only one beam would be generated at any moment in time).

Each moving mirror, 3 may be addressed by one or more light sources, 1.

Preferably, the light bus has a central light source for each particular output wavelength that the light bus is desired to provide -so, for example, . if the light bus is required to provide outputs at 3 different wavelengths (e.g. red, green, blue) then the light bus would have 3 central light sources (R, G, B) that addressed the mirror. Preferably each moving mirror is addressed by between 2 and 10 light sources. It should be emphasised that, in an embodiment in which two or more central light sources are present, an optical fibre 5 may selectively receive light from any of the central light sources, for example to obtain a desired output wavelength in the case of R,G,B light sources (or from none of the light sources, if zero light output is desired). This is in contrast to US 5713654, in which there is a fixed one-to-one correspondence between optical fibres and light sources.

The light source, 1 may emit white light, light with a wavelength of 405nm, light with a wavelength of 450nm or light with any wavelength in the visible spectrum of 400-700nm. Alternatively the light source, 1 may comprise an array of light emitters which emit at red, green and blue wavelengths such that the combined output of the light sources is substantially white light. Preferably the light source, 1 may constitute an array of InGaN lasers which emit light at a wavelength of 405nm.

The light output of each optical fiber, 5 may be of the same wavelength as the light generated by the light source, 1 and coupled into the optical fibre 5, and thus may be substantially white or any other wavelength in the visible spectrum of 400-700nm (depending on the output light from the central light source). Alternatively, one or more of the optical fibers, 5 may be coated at its end with a light sensitive phosphor, such that the light emitted from the end of the fiber has a substantially different wavelength to the light coupled into the fiber, as disclosed in 5OO921 84A1. Additionally or alternatively one or more of the fibers, 5 may contain a fluorescent core, such that the light emitted from the fiber has a substantially different wavelength to the light coupled into the fiber as detailed in US7505655. Additionally or alternatively one or more fibers, 5 may be coated along its entire length or along selected sections of its length with a light sensitive phosphor, such that the light emitted from the side of the fiber or fibers has a substantially different wavelength to the light coupled into within the fibers. Additionally or alternatively the light coupled into the fibers, 5 may have a single wavelength (eg a wavelength of 405nm), and the fibers, 5 are coated at their end or at selected sections along their length with a light sensitive phosphor such that the light emitted by the fibers is white light.

The optical fiber array, 5 may contain multiple optical fibers between I and 500 in number. The number of optical fibers may be between 10 and 100.

Preferably the number of optical fibers is between 10 and 50. The optical fiber may comprise plastic optical fiber or silica optical fiber. Ideally the optical fiber During operation the high brightness light source, 1 may produce a significant amount of heat, thus the light source may be coupled to a heat sink or thermal electric cooler, 10 contained within the light bus unit, 9 as shown in Figure 4.

For the provision of cooling to multiple light sources,1 the light bus may contain two or more heat sinks or thermal electric coolers, 10, as shown in Figure 4. Preferably the light bus, 9 would contain one thermal electric cooler or heat sink, 10 to provide cooling to all the light sources, 1 within the light bus, 9 in order to minimise the weight and the size of the unit.

The light bus, 9 may also contain a photodiode, 7, for the purpose of monitoring the position and/or orientation of the moving mirror 3, where the mirror is a free moving mirror and the position/orientation of the mirror is not accurately known by the driver circuitry, 8. The moving mirror, 3 may reflect one light beam, 6 onto a photodiode, 7, which is in turn connected to the driver circuitry, 8. The light bus, 9 containing a photodiode, 7 is also shown in Figure 4. The provision of a photodiode, 7 is preferably not required, where the position/orientation of the moving mirror, 3 is known and determined by the driver circuitry, 8. This embodiment is not limited to one photodiode, and two or more photodiodes may be provided to ensure accurate position/ orientation determination. Also, the embodiment of Figure 4 is not limited to photodiodes and other types of light sensors that can detect the light beam 6 may be used.

As explained above, the light output by each of the optical fibres or optical fibre bundles 5 may be independently controlled by varying the position and/or orientation of the mirror 3. In addition, the brightness at each output is preferably also controlled by means of the circuitry 8 controlling the intensity of light output by the light source 1, independent of the position and/or orientation of the mirror 3. This allows the brightness of an output to adopt values intermediate between "fully ON" and "OFF", which are controlled by varying the brightness of the central light source. This may be done by varying the drive current supplied to the light source 1 or, in the case of a pulsed light source, varying the duty ratio of the drive current to change the proportion of time for which the light source 1 is ON.

An embodiment of the present invention is described with reference to figure 5 and figure 6. Figure 5 shows a side view schematic of a car, 11 containing a light bus, 9 in accordance with the present invention. The light bus, 9 is conveniently located on the vehicle and provides light into a series of optical fibers or optical fibre bundles, 5. The optical fiber or fiber bundle, 5 then transmit the light from the light bus, 9 into various optical loads on the vehicle.

Figure 5 shows a vehicle equipped with several optical loads commonly found inside and on the outside of a car, such as taillights, 13 headlights, 14 interior reading light, 15 and dashboard light, 16. In this embodiment each optical load, 13-16 is illuminated via a separate optical fiber or fiber bundle, 5. Figure 6 shows a plan view of the vehicle, 11 containing the light bus, 9 according to the first embodiment of the invention. The optical fibers, 5 are shown to distribute light from the light bus, 9 to optical loads on both the left hand and right hand sides of the vehicle. The driver circuitry, 8 is connected to the pedals and switches within the car to enable the driver to activate many of the optical loads on the vehicle as required. Other optical loads, are controlled via sensors which are connected directly to the driver circuitry, 8, such as the fuel level indicator or oil level indicator. Figure 7 shows a schematic of the light bus inputs, 18, 20, 22, 24, 26 and 28 and optical outputs, 19, 21, 23, 25, 27 and 29 according to the first embodiment of the invention. An input signal to the light bus may be provided by, for example, the brake pedal, 20 when it is depressed by the vehicle driver, which then stimulates the light bus to send light to the brake light, 21. As a further example the light bus may receive a signal from the car indicator switch or lever, 28 when it is activated, which tells the light bus to send light to the indicator light, 29. In this way the driver has complete control over the operation of all the optical outputs on the vehicle.

The light bus, 9 may be conveniently located anywhere on the vehicle to allow access for maintenance. The light bus, 9 may be ideally located away from large heat sources on the vehicle, 11 such as the engine to enable the temperature of the light sources, 1 to be controlled and maintained. The driver circuitry, 8 may be located within the light bus unit, 9 or may be remotely located. The driver circuitry, 8 may be preferably located remotely from the light bus, 9 in order to isolate it from the heat generated by the light sources, 1. Preferably the driver circuitry, 8 may be located with other electronic circuitry within the car.

A vehicle may contain one or more light buses, 9. Preferably the vehicle would contain two light buses, 9 one to supply light to the optical loads on one side of the vehicle and a second light bus, 9 to provide light to optical loads on the other side of the vehicle. The provision of more than one light bus on the vehide provides redundancy should one light bus fail or be damaged in a collision.

Figures 8 and 9 show a vehicle, in this example a road vehicle, containing a light bus, 9 according to a further embodiment of the present invention. The elements 9, 10, 11, 13, 14, and 15 are as described in the above embodiment. In the above embodiment light from the light bus, 9 is supplied to each of the optical loads, 13, 14, 15 and 16 through separate optical fibers or fiber bundles, 5. In the further embodiment a common optical fiber, 12 may deliver light to a series of low brightness optical loads, such as interior light 15, dashboard lighting 16 and door lighting 17. Low brightness optical loads on the vehicle may have brightness up to 20 Lumens. Preferably the low brightness optical loads have up to 10 Lumens. The side door lighting, 17 is additional to the optical loads described in the embodiment of Figures 4 and 5. The advantage of such a common optical fiber line is the reduction of the number and length of optical fibers required to address all the optical output and also the ease with which additional optical loads may be added to the lighting circuit without the need for additional optical fiber. The use of a common optical fiber for vehicle lighting is described in US6206533. The input controls to the light bus in this embodiment are as described for the first embodiment of the invention and as shown in figure 6.

The vehicle of figures 8 and 9 may contain one or more common optical fibers, 12. Preferably the vehicle would contain between 2 and 5 common optical fibers, 12. Preferably the light bus, 9 would deliver light to high brightness optical loads on the vehicle, such as the taillights, 13 and headlights, 14 through individual optical fibers or fiber bundles, 5. High brightness optical loads may have brightness between 50 and 5000 lumens.

Preferable the high brightness loads will have brightness between 1000 and 2000 Lumens. Preferably the low brightness optical loads on the vehicle would all be supplied light from the light bus, 9 using common optical fibers, 12.

In a further embodiment of the invention, a light bus, 9 of the invention may be used to supply light to different rooms of a building such as a home or office, as shown in Figure 10. The light bus, 9 may be conveniently located in the attic, as shown in Figure 10 or in any chosen location within the house, 50 to assist maintenance access. The light bus, 9 may supply light to ceiling lights, 51 and wall lights, 52 in different rooms in the house, 50 through individual fibers or fiber bundles, 5. A common optical fiber, 12 may deliver light to an array of ceiling lights, 53. A common optical fiber may also supply light to a lamp, 55 inside a refrigerator, 54 or any other cold storage appliance. The optical loads may all be supplied with separate optical fibers or fiber bundles, or the optical loads may be supplied by one or more common optical fibers.

Preferably the optical loads may be supplied by a combination of individual optical fibers or fiber bundles, 5 and common optical fibers, 12. The light bus, 9 may be used to supply light to other optical loads inside or outside a home, which may include but is not limited to decorative lighting, security lighting, garden lighting and exterior building lighting. The light bus, 9 may be used for lighting in bathrooms, wet rooms, showers or other high moisture environments, where it is ideally suited, because it does not present the threat of electrocution associated with conventional electrically wired lighting.

One or more light buses, 9 may be used to supply lighting to the whole building or parts of the building. Preferably two light buses would supply the lighting to the whole of the building, in order to provide a back-up source, in the case of a failure of one of the optical buses.

The invention has been described with reference to lighting in automobiles and homes. However, the present invention of a light bus is not limited to these applications. The light bus may be extended for use in any situation where remote source lighting is advantageous. This includes, but is not limited to, shopping centres, car parks, exterior building lighting, displays, swimming pools, runways and roadways.

Claims

CLAIMS: 1. A remote source lighting system, the system comprising: a light source; a plurality of light outputs; and a single coupler for selectively coupling light from the light source towards one or more desired ones of the light outputs.
2. A system as claimed in claim 1 wherein the coupler, in use, splits light from the light source into a plurality of light beams, and selectively couples the light beams to respective ones of the light outputs.
3. A system as claimed in claim 1 or 2 and comprising a plurality of light guides, each light guide directing light, in use, to a respective one of the light outputs; and wherein the coupler is adapted to selectively couple light from the light source into one or more selected ones of the light guides.
4. A system as claimed in claim 2 or 3 wherein the coupler comprises a single reflector unit.
5. A system as claimed in claim 4 wherein the coupler comprises a moveable and/or re-orientable reflector.
6. A system as claimed in claim 5 wherein the reflector comprises multiple reflecting surfaces adapted to reflect light from the light source in multiple different directions.
7. A system as claimed in any preceding claim and further comprising a second plurality of light outputs; and a second single coupler for selectively coupling light from the light source towards one or more desired ones of the second plurality of light outputs.
8. A system as claimed in claim 5 or 6 and comprising a first driver circuit for controlling the position and/or orientation of the reflector.
9. A system as claimed in claim 5 or 6 and comprising a sensor for determining the position and/or orientation of the reflector.
10. A system as claimed in claim 8 wherein the first driver circuit is adapted to control the position and/or orientation of the reflector on the basis of a user input.
11. A system as claimed in any preceding claim and comprising a second driver circuit for controlling the light output from the light source.
12. A system as claimed in any preceding claim wherein the light source comprises an array of illumination sources.
13. A system as claimed in any preceding claim wherein the light source comprises two or more independently controllable illumination sources.
14. A system as claimed in any preceding claim and further comprising a common light guide having a plurality of light outputs.
15. A vehicle comprising a remote source lighting system as defined in any one of claims ito 14.
16. A building comprising a remote source lighting system as defined in any one of claims ito 14.