Field

The present invention relates to a system , apparatu ses, and a method for lighting a vehicle.

Background

By law, road vehicles are required to provide a light cluster at their rear. This light cluster includes, for example, brake lights, tail lights, and indicator lights. When the vehicle is a car towing a trailer, such as a wood chipper or caravan , the lights in the clu ster on the rear of the car become obscured. Therefore, it is also necessary for the trailer to provide the same light cluster as the car.

So that the trailer's light cluster can be powered and controlled, an umbilical is u sed to couple the trailer to an electrical socket at the rear of the car. In a challenging environment, such as a forest, this umbilical can easily become damaged or be pulled from the socket. Furthermore, in long vehicles, a large amount of cabling is necessary to couple the rear lights to the electrical power supply. This is not desirable, especially where reducing weight is a concern .

Battery-operated lights are known for u se on bicycles. However, these lights are controlled by way of an on/ off switch on the light itself, not the u ser operating brake handles, for example. Therefore, simply providing battery-operated lights on the rear of a trailer would not solve the aforementioned problem .

Aspects of the present invention aim to address one or more drawbacks inherent in prior art systems for lighting a vehicle.

Sum m ary

According to a first aspect of the present invention , there is provided a vehicle lighting system comprising:

at least one light unit having at least one light source;

a wireless interface; and

a first controller configured to:

receive a u ser input ,

generate a control signal corresponding to the user input, and transmit the control signal to control the at least one light source through the wireless interface.

Advantageously, the vehicle lighting system provides a means to wirelessly control a light. For example, in a vehicle having a drive unit and a trailer, or in a long rigid vehicle where it would be difficult to install wiring, the vehicle lighting system enables light sources at the rear of the vehicle to be controlled from the front of the vehicle without the use of wiring. Where a vehicle has a drive unit and trailer, the present invention eliminates the requirement for an umbilical between the drive unit and trailer, which can become damaged or come loose during use.

Preferably, the light unit is a housing having a cover for protecting the at least one light source. The cover may have different colours in different sections to correspond with each of the plurality of light sources. For example, the portion of the cover covering a brake light may be red, and the portion of the cover covering an indicator light may be orange. Alternatively, the light sources may be individu ally coloured, and here the cover is clear. In some embodiments, the light unit is a holder for securing the light sources . Preferably, the vehicle lighting system comprises a second controller for receiving the control signal and controlling the at least one light source according to the received control signal. Preferably, first controller is configured to generate a control signal indicating a light source to be controlled. Even more preferably, the second controller is configured to read control instructions corresponding to the indicated light source and control the light source according to the control instructions. For example, the control instructions may specify to control an indicator light to flash intermittently until another control signal is received. Alternatively, the first controller may be configured to generate a control signal indicating a light source to be controlled and indicating how to control the indicated light source.

Preferably, the vehicle lighting system comprises a power supply arranged to power the second controller. Even more preferably, the power supply is arranged to power the at least one light unit in accordance with the transmitted control signal. Preferably, the at least one light unit comprises the power supply. The power supply preferably comprises at least one of a battery, solar cell, capacitor, inductance coil, and an electric generator. Examples of an electric generator include a dynamo and an alternator. Even more preferably, the vehicle lighting system comprises a capacitor arranged between the power supply and the at least one light unit and/ or the second controller.

More preferably, the power supply comprises a first power supply arranged to power the at least one light unit, and a second power supply arranged to power the second controller.

Preferably, the at least one light source is a light emitting diode. Alternatively, the light source is an incandescent light bulb , such as a halogen or argon lamp . The at least one light source preferably comprises at least one of a brake light, reversing light, indicator light, a tail light and a fog light.

Preferably, the wireless interface comprises a transmitter for u se in a drive unit of the vehicle, and a receiver for u se in a trailer unit of the vehicle. Preferably, the wireless interface comprises a Bluetooth™ interface. Alternatively, the wireless interface comprises a Zigbee, LTE, NFC, WiMax or Wi-Fi interface. Even more preferably, the transmitter comprises a mobile device for receiving the generated control signal and transmitting the control signal to the receiver. For example, the mobile device is a cellular phone.

Preferably, the vehicle lighting system comprises a control unit comprising the wireless transmitter and/ or the first controller. Even more preferably, the control unit is configured to be coupled to a tail light socket on the drive unit. Preferably, the vehicle lighting system comprises a tail unit, the tail unit comprising the second controller, wireless receiver and the at least one light unit. Even more preferably, the tail unit further comprises the power supply.

Preferably, the second controller is configured to control a switch arranged between the controller and the at least one light unit in accordance with the received control signal. Even more preferably, the second controller is arranged to control a plurality of switches, wherein one of the plurality of switches is arranged between the controller and each of the light sources. According to a second aspect of the present invention , there is provided a trailer unit for a vehicle comprising: a light unit having at least one light source;

a wireless receiver for receiving a control signal; and

a controller configured to control the at least one light source according to the control signal.

Preferably, the controller is configured to read control instructions corresponding to a light source indicated by the control signal and control the light source according to the control instructions. Preferably, the trailer unit comprises at least one power supply arranged to power the light unit, wireless receiver and the controller. More preferably, the power supply comprises a first power supply arranged to power the at least one light unit, and a second power supply arranged to power the controller. Preferably, the power supply is arranged to power the at least one light unit in accordance with the transmitted control signal.

Preferably, the at least one light source is a light emitting diode.

Preferably, the at least one light source comprises at least one of a brake light, reversing light, indicator light, a tail light and a fog light.

Preferably, the receiver comprises a Bluetooth™ receiver.

Preferably, the controller is configured to control a switch arranged between the controller and the at least one light unit in accordance with the received control signal. More preferably, the controller is arranged to control a plurality of switches, and one of the plurality of switches may be arranged between the controller and each of the light sources . According to a third aspect of the present invention , there is provided a drive unit for a vehicle comprising:

a user input device ;

a wireless transmitter ; and

a controller configured to generate a control signal for controlling at least one light source according to a u ser input and control the wireless transmitter to transmit the control signal. For example, the u ser input device may be a brake pedal or an indicator stalk.

The controller is preferably configured to generate a control signal indicating the light source to be controlled. Alternatively, the controller is configured to generate a control signal indicating a light source to be controlled and indicating how to control the indicated light source.

Preferably, the transmitter comprises a Bluetooth™ transmitter.

Preferably, the transmitter comprises a mobile device for receiving the generated control signal and transmitting the control signal to a receiver.

According to a fourth aspect of the present invention , there is provided a vehicle comprising the trailer unit according to the second aspect and the drive unit according to the third aspect.

According to a fifth aspect of the present invention, there is a provided a method of wirelessly lighting a vehicle comprising:

receiving a u ser input ;

generating a control signal corresponding to the user input ; and

transmitting the control signal to control at least one light source through a wireless interface. Preferably, the method comprises receiving the control signal and controlling the at least one light source according to the received control signal. Preferably, the method comprises generating a control signal indicating a light source to be controlled. Even more preferably, the method comprises reading control instructions corresponding to the indicated light source and controlling the light source according to the control instructions. For example, the control instructions may specify to control an indicator light to flash intermittently until another control signal is received. Alternatively, the method may comprise generating a control signal indicating a light source to be controlled and indicating how to control the indicated light source.

Preferably, the at least one light source is a light emitting diode. Alternatively, the lig source is an incandescent light bulb , such as a halogen or argon lamp . The at least on light source preferably comprises at least one of a brake light, reversing light, indicator light, a tail light and a fog light.

Preferably, the wireless interface comprises a transmitter for u se in a drive unit of the vehicle, and a receiver for u se in a trailer unit of the vehicle. Preferably, the wireless interface comprises a Bluetooth™ interface. Alternatively, the wireless interface comprises a Zigbee, LTE, NFC, WiMax or Wi-Fi interface. Even more preferably, the transmitter comprises a mobile device for receiving the generated control signal and transmitting the control signal to the receiver. For example, the mobile device is a cellular phone.

Preferably, the method comprises controlling a switch to provide power to the at least one light unit in accordance with the received control signal. Even more preferably, method comprises controlling a plurality of switches to provide power to each of a plurality of light sources independently.

All features described herein (including any accompanying claims, abstract and drawings), and/ or all of the steps of any method or process so disclosed, may be combined with any of the above aspects in any combination , except combinations where at least some of such features and/ or steps are mutually exclusive.

Brie f De scription of th e Figures

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

Figure 1 is a side view of a vehicle according to an embodiment of the present invention ;

Figure 2 is a system diagram of a vehicle lighting system according to an embodiment of the present invention ;

Figure 3 is a system diagram of a light unit according to an embodiment of the present invention ;

Figure 4 is a system diagram showing a vehicle lighting system according to another embodiment of the present invention ;

Figure 5 is a system diagram showing a power supply for a vehicle lighting system according to the embodiment shown in Figure 4 ;

Figure 6 is a system diagram showing a vehicle lighting system according to another embodiment of the present invention ; Figure 7 shows a flow chart for the steps of carrying out a method of lighting a vehicle according to an embodiment of the present invention ;

Figure 8 is a system diagram showing a vehicle lighting system according to another embodiment of the present invention ; and

Figure 9 shows a flow chart for the steps of carrying out a method of lighting a vehicle according to an embodiment of the present invention.

Detaile d Description

With reference to Figure 1, a vehicle 100 is shown as having a drive unit 10 and a trailer unit 20. For example, the drive unit 10 is a car, jeep, van, 4x4, train locomotive, tractor, or lorry. The trailer unit 20 is, for example, a wood chipper, caravan, articulated lorry trailer, boat transporter, bicycle rack, train carriage or flatbed trailer. While the invention will be described in the context of road vehicles, the skilled person would appreciate that the invention described herein can equally be applied to a long rigid vehicle such as an aircraft or a nautical vessel. Aircraft and nautical vessels, such as ships, require navigation lights at their port and starboard periphery. These navigation lights are activated by a switch in the cockpit or bridge. Reducing wiring is particularly advantageous in aircraft, where weight savings show a marked increase in efficiency. In the embodiment shown in Figure 1, the drive unit 10 and trailer unit 20 are coupled by a mechanical linkage 30 (or a towbar). There is no wired electrical connection between the drive unit 10 and the trailer unit 20. The trailer unit 20 includes a light 28 at its rear. The light 28 is, for example, a brake light, an indicator light, a fog light, or a reversing light. In some embodiments, the trailer unit 20 comprises a plurality of lights 28 , which may be a plurality of the same type of lights, or a light cluster having several different types of lights.

The light 28 at the rear of the trailer unit 20 is controlled from the drive unit 10. That is to say the light 28 may be activated according to a user input in the cockpit of the vehicle 100. Where the light 28 is a brake light, the light 28 is controlled to be on or off according to a user input such as depressing a foot brake or lifting a hand brake. Where the light 28 is an indicator light, the activated light 28 intermittently flashes on and off for a predetermined amount of time in response to a user input. In this embodiment, the user input may be pushing an indicator stalk in the cockpit of the vehicle 100. Figure 2 shows a lighting system 200 for use in the vehicle 100. The lighting system 200 according to the embodiment shown in Figure 2 includes a plurality of light units 22a, 22b (or light clu sters) . Each light unit 22a, 22b includes a plurality of lights 28 a-d. However, in other embodiments, there may only be one light unit 22. Furthermore, each light unit 22a, 22b , or the light unit 22, may only include one light 28 instead of the plurality of lights 28 a-d shown in Figure 2. The light units 22a, 22b are

independent units that can be attached to the rear of a vehicle 100.

Each light unit 22a, b is a housing having a cover for protecting the lights 28. The cover may have different colours in different sections to correspond with each of the plurality of light sources. For example, the portion of the cover covering a brake light 28 b is red, and the portion of the cover covering an indicator light 28 a is orange. Alternatively, the lights 28 may be individu ally coloured, and here the cover is clear. In some

embodiments, the light units 22a, 22b are holders for securing the lights 28 a-d.

The plurality of light units 22a, 22b shown in Figure 2 are controlled centrally. The light units 22a, 22b are controlled by a controller 24. On receiving a signal from the controller 24, switches are controlled so that the correct light 28 a-d in each of the light units 22a, 22b is activated. For example, the outer lights 28 a, 28 d may be indicator lights, and the inner lights 28 b , 28 c may be brake lights. When the user pushes an indicator stalk to indicate the vehicle 100 is about to turn left, the controller 24 controls switches such that only the outer light 28 a on the left-hand side is activated. Similarly, the lights 28 a-d may comprise reversing lights, parking lights, fog lights or navigation lights.

The controller 24 according to some embodiments includes a memory 23. The memory 23 may alternatively be separately provided. The memory 23 stores instructions for activating lights 28 a-d or light units 22a, 22b according to a received control signal. The wireless signal received through the wireless receiver 32b is processed by the controller 24. The wireless receiver 32b may separately provided to the controller 24, or may be integrated with the controller 24. The processed control signal may indicate which lights 28 a-d are to be controlled, or may additionally indicate how the indicated lights 28 a-d are to be controlled. For example, the control signal may indicate that an indicator light is to be controlled to flash three times. Alternatively, the controller 24 may search the memory 23 for control instructions for controlling a light 28 a-d indicated by the control signal. In some embodiments, a power supply 26a, 26b is disposed in each light unit 22a, 22b . Here, the controller 24 selectively turns each of the power supplies 26a, 26b on and off. In other embodiments, one power supply 26 is arranged to supply power to a plurality of light units 22a, 22b . Here, switches are controlled to direct power to the light unit 22a, 22b or light 28 -d indicated by the control signal.

The trailer unit 20 has its own central power supply 27 for powering lighting control components. The lighting control components include the controller 24 and the wireless receiver 32b. The wireless receiver 32b in the trailer unit 20 is a wireless receiver. In some embodiments, described later with reference to Figures 4 to 6 , the same power supply 27 for powering the lighting control components is used to power the lights 28 a-d. In the embodiment shown in Figure 2, separate power supplies 26a, 26b in each of the plurality of lighting units 22a, 22b are u sed for driving the lights 28 a- d.

The power supplies 27, 26a, 26b described herein may be batteries or capacitors. The batteries may be rechargeable batteries. Alternatively, the central power supply 27 is an electric generator. For example, the electric generator is a dynamo or alternator that u ses the movement of part of the vehicle 100 , such as an axle, wheel or engine rotor to induce a current. A dynamo is a direct current electrical generator, and an alternator is an alternating current electrical generator. The power supplies 27, 26a, 26b may also be solar cells. Furthermore, the central power supply 27 may be an inductive coupling, where one part of the inductive coupling (a first coil) is disposed at the front of the trailer unit 20 the other part (a second coil) is disposed at the rear of the drive unit 10. In other words, the two parts of the inductive coupling are arranged in proximity to each other. Here, an alternating electromagnetic field generated at the drive unit 10 by passing a current through a coil is u sed to induce a current at the trailer unit 20. This induced current may be used directly by the control components and used to charge the power supplies 26a, 26b in each of the light units 22a, 22b . Further embodiments will be described later with reference to Figures 4 to 6.

The wireless receiver 32b is wirelessly coupled to a wireless transmitter 32a in the drive unit 10. The wireless transmitter 32a and wireless receiver 32b are two parts of the same wireless interface 32. The wireless interface 32 could be a Bluetooth™ interface. Alternatively, the wireless interface 32 is a Zigbee, LTE, NFC, WiMax or Wi-Fi interface. The drive unit 10 includes a user input device 12 for controlling the lights 28 a-d disposed at the rear of the trailer unit 20. The user input device 12 may have multiple functions, such as to activate the vehicle's 100 brakes as well as the lights 28 a-d, or to change the gear of the vehicle 100 as well as activating the lights 28 a-d.

The user input device 12 is coupled to a controller 14. The controller 14 includes a signal generator 18 and a memory 16. When a user input is received at the user input device 12, the signal generator 18 generates an electrical signal corresponding to the received user input. For example, the signal generator 18 may use a lookup table stored in the memory 16 to map the user input with a particular signal frequency.

Alternatively, the signal generator 18 may append a different header to a data stream according to the type of user input received. The generated signal in some

embodiments indicates a light 28 to be controlled. In other embodiments, the generated signal contains control instructions indicating how to control the light 28.

In some embodiments, the controller 14 comprises the wireless transmitter 32a. In other words, in these embodiments, retrofitting the invention into a drive unit 10 is straightforward as it only requires one device to be coupled to the user input device 12. The wireless transmitter 32a, or the controller 14 having the wireless transmitter 32a may be plugged directly into an electrical socket disposed at the rear of the drive unit 10 ; the electrical socket being the same electrical socket used in the prior art for wired connections between the drive unit 10 and trailer unit 20. Typically, vehicles 100 having trailer units 20 are equipped with a towbar 30 , either at the point of

manufacture or retrofitted afterwards. The towbar 30 according to the prior art typically provides a mechanical and electrical linkage between the drive unit 10 and trailer unit 20. According to some aspects of the present invention, instead of an electrical umbilical being used to connect the towbar 30 to the trailer unit 20 , a transmitter unit comprising the wireless transmitter 32a and the controller 14 is coupled to the electrical socket on the towbar 30.

As well as receiving electrical control signals through the electrical socket at the rear of the drive unit 10 , or disposed in the towbar 30 , the transmitter unit is powered through the electrical socket. In other words, the transmitter 32a and controller 14 are powered by the main power source of the drive unit 10. This may be an internal combustion engine, connected to an alternator. Alternatively, in an electrically-driven vehicle, this main power source is a battery pack. Alternatively again, the transmitter unit includes its own independent power source, and so only receives control signals through the electrical socket. Alternatively, the controller 14 and wireless transmitter 32a may be part of a mobile device such as a mobile phone or tablet computer. The mobile device may be coupled to the user input 12 through a wired interface such as a USB or HDMI interface.

Alternatively again, the controller 14 may be separately provided to the mobile device. Here, the mobile device acts as a wireless transmitter 32a in communication with the wireless receiver 32b in the trailer unit 20.

Figure 3 shows one of the light units 22a of embodiments described with reference to Figure 2 in more detail. Here, the lights 28 a, 28b are electrically coupled by switches 34a, 34b to the power supply 26a for the light unit 22a. The switches 34a, 34b are controlled by the controller 24 according to a control signal received through the wireless receiver 32b. The switches 34a, 34b are shown as being transistor switches. However, any type of electro-mechanical switching gear may be used, such as a relay. For example, the switches 34a, 34b may part of the controller 24, or embedded in the lights 28 a, 28b.

In use, the controller 24 receives a control signal from the drive unit 10 via the wireless interface 32. The control signal is decoded, and the decoded control signal indicates which of the lights 28 a, 28 b should be activated. The controller 24 transmits a signal to close the switch 34a, 34b corresponding with the light 28 a, 28 b to be activated. When a switch 34a, 34b is closed, electrical current is able to flow from the power supply 26a to the light 28 a, 28b through the switch 34a, 34b.

A lighting system 300 according to another embodiment will now be described with reference to Figure 4. The drive unit 10 may be as described in any of the embodiments above, and so description of which will not be repeated here.

In the embodiment shown in Figure 4, the light units 22a, 22b are not independently powered. Instead a central power supply 27 is used to power all of the components of the lighting system 300 that are disposed in the trailer unit 20. A capacitor 29 is shown in Figure 4 for storing current generated by the power supply 27. The capacitor 29 then supplies current generated by the power supply 27 to the lighting control components, such as the controller 24 and wireless receiver 32b , and the lights 28 a-d. The lights 28 a-d are selectively powered according to signals generated by the controller 24 for controlling the switches 34a-d, as described with reference to Figure 3. The capacitor 29 may be used to store current, or to smooth a fluctuating supply.

In alternative embodiments, the capacitor 29 is not necessary. Alternatively, the capacitor 29 may be disposed so as to power the lights 28 a-d, but the lighting control components are continuously supplied with power directly by the power supply 27.

The power supply 27 is, for example, a battery, a solar cell, or an electric generator such as a dynamo or an alternator. This will be described in more detail with reference to Figure 5.

As shown in Figure 5, the trailer unit 20 includes two wheels 38 a, 38b coupled together by an axle 36. The axle 36 rotates as the wheels 38 a, 38b are pulled along the ground by the drive unit 10. Here, the power supply 27 is an electric generator placed in contact with the axle 36. In alternative embodiments, the axle 36 is static, and the wheels 38 a, 38b rotate about the axle 36. Here, the electric generator is placed in contact with one of the wheels 38 a, 38b.

An electric generator comprises a rotor and a stator, each having a number of magnets. The magnets in the stator are wrapped in coil of wire. When the rotor rotates, an alternating magnetic field is generated, which induces an alternating current in the coil of wire. According to some embodiments, this alternating current is smoothed into an effectively direct current by a capacitor 29. Where the power supply 27 is an electric generator, in some embodiments the rotor of the electric generator is driven by an aerofoil (i.e. a fan) attached to the outside of the trailer unit 20. The aerofoil rotates when it comes into contact with air moving relative to the trailer unit 20. Figure 6 shows a lighting system 400 for a vehicle 100 according to another embodiment. Here, the features of the lighting system 400 disposed in the trailer unit 20 are provided as one device. In other words, a single light unit 22 is provided. The light unit 22 includes the lights 28 a-d, power supply 27, and wireless receiver 32b. This improves the ease with which the lighting system 400 can be retrofitted into an existing trailer unit 20.

A method of controlling lights 28 of a vehicle 100 will now be described with reference to Figure 7. In a first step 600 , a user input is received. The user input is the activation of a control which turns a light 28 on or off. For example, the user input is the depression of a foot brake, actuation of an indicator stalk, or manipulation of a gear stick.

In step 610 , a control signal is generated. The control signal indicates which of a plurality of types of lights 28 is to be activated. For example, for a brake light to be switched on, a first control signal is generated. For a reversing light to be switched on, a second control signal is generated, different to the first control signal. For example, the first and second control signals are of different frequencies or amplitudes. The control signal may indicate which light 28 is to be controlled, as well as indicating how the light 28 is to be controlled. For example, the control signal may contain command instructions to cause an indicator light to flash for a predetermined amount of time, or until another control signal relating to the steering wheel of the vehicle 100 is received. Alternatively, the control signal indicates only which of the lights 28 is to be controlled.

In step 620 , the control signal is wirelessly transmitted using a transmitter part 32a of a wireless interface 32. The control signal may be transmitted using any known wireless communication standard, such as Bluetooth™, LTE, Wi-Fi, Zigbee, WiMax, and NFC. Preferably, the control signal is transmitted using Bluetooth™.

The transmitted control signal is received by a receiver part 32b of the wireless interface 32 at step 630. The received control signal indicates which of a plurality of lights 28 are to be switched on or off. Where there is only one light, the control signal indicates that the light 28 is to be switched on or off.

In step 640 , the lights 28 are controlled according to the processed control signal. The controller 24 controls the lights 28 according to the control signal. If the control signal does not contain instructions for controlling the light 28 , the controller 24 may search memory 23 for instructions for controlling the light 28 indicated in the control signal. The control instructions may be read from a lookup table. The controller 24 controls switches 34 in order to turn the determined lights 28 on or off.

Figure 8 shows a lighting system 700 for a vehicle in accordance with another embodiment. The system 700 comprises a drive unit 10 , a trailer unit 20 and a remote unit 710. As described above, the drive unit 10 includes the user input device 12, controller 14 (including memory 16 and signal generator 18) and wireless transmitter 32a as described above. As described further below, in the system 700 , the wireless connection between the drive unit 10 and the trailer unit 20 is bi-directional such that the wireless transmitter 32a may be a transceiver; alternatively, a separate wireless receiver (not shown) may be provided. Similary, the trailer unit 20 includes a wireless receiver 32b, which may be a transceiver (or a separate wireless transmitter - not shown - may be provided).

The trailer unit 20 also includes a controller 24 and a plurality of lights 28 -d as described above.

The trailer unit 20 of the system 700 differs from previous embodiments in the provision of driver circuits 701 to 704 provided between the controller 24 and the respective lights 28 a-d.

As shown in Figure 8 , each driver 701 to 704 is in two-way communication with the respective light 28 a-d. Each driver controls the respective light on the basis of control signals from the controller 24. The drivers 701 to 704 can be used to optimise the output of the lights 28 a-d for maximum efficiency. For example, each driver may be used to control the current and/ or the voltage of the respective light. The lights may be light emitting diodes (LEDs). The performance characteristics of LEDs is well understood, accordingly the current and voltage of LEDs can be controlled quite precisely in order to provide a desired output at high efficiency (therefore reducing power low and heat generation).

By monitoring the current and/ or voltage of the lights 28 a-d, the drivers 701 to 704 can also be used to detect lighting faults. Such faults are reported to the controller 24 and then to the drive unit controller 14 via the wireless interface. The drivers 701 to 704 can also be u sed to control the brightness of the relevant lights. Thus, for example, a light may have different brightness in different modes of operation . This can be readily controlled by the drivers. For example, in some countries, the brightness required from the lights 28 a-d may be different. The drivers 70 1 to 704 can be used to change the brightness of the lights under the control of the controller 24 in the event that the vehicle moves from one country to another country.

As shown in Figure 8 , the system 700 also comprises a remote unit 710. The remote unit 710 includes a wireless transceiver 712, a controller 714 and a u ser interface 716. The remote unit 710 can be u sed in some embodiments of the invention to test the trailer unit 20. For example, the remote unit may instruct the drivers 70 1 to 704 to operate the lights 28 a-d and to report that the lights are operating normally. The drivers 70 1 to 704 may also report faults to the remote unit 710 during the normal operation of the system 700 (instead of, or in addition to, reporting faults to the drive unit 10).

Figure 9 shows a flow chart for the steps of carrying out a method of lighting a vehicle according to an embodiment of the present invention . The flow chart includes the receive unit input, generate control signal, transmit control signal and receive control signal steps 600 , 610 , 620 and 630 described above with reference to Figure 7.

Following the reception of control signal at the trailer unit (step 630), the control signals are sent to the drivers 70 1 to 704 described above (step 8 10) . The drivers 70 1 to 704 adju st the light outputs (typically LEDs) 28 a-d in accordance with the control signal (step 820). For example, the drivers 70 1 and 704 may control the voltage and/ or current of LEDs that form the light outputs 28 a-d. As noted above, the drivers 70 1 to 704 may be used to control LED brightness. This may be achieved by altering the current and/ or voltage of the LED signals, but alternative arrangement are possible. For example, pulse width modulation (PWM) may be used.

At step 830 , the drivers 70 1 to 704 provide feedback to the controller 24 regarding the performance of the respective light 28 a-d. For example, the drivers 70 1 to 704 may provide feedback (to the controller 24) in the event that an LED has a voltage and/ or a current outside a normal operation range (as this might be indicative of a fault). In the event that a potential fault is identified, the controller 24 is required to take action (at step 840). This action might, for example, include providing a warning to the drive unit 10 and/ or providing a warning to the remote unit 710. Advantages of the vehicle lighting systems described herein reside in the lights 28 being wirelessly controlled, so that a wired linkage between a user input device 12 and the light 28 is not necessary. Therefore, in a vehicle 100 having a drive unit 10 and a trailer unit 20 , an umbilical between the units is not required. Although a few exemplary embodiments have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles of the invention , the range of which is defined in the appended claims.