GB2405272A

GB2405272A - Vehicle lamp

Info

Publication number: GB2405272A
Application number: GB0418093A
Authority: GB
Inventors: David Stanners; Matthew Holmes
Original assignee: Nissan Technical Centre Europe Ltd
Current assignee: Nissan Technical Centre Europe Ltd
Priority date: 2003-08-19
Filing date: 2004-08-13
Publication date: 2005-02-23
Anticipated expiration: 2024-08-13
Also published as: GB0524233D0; EP1660351A1; GB2405272B; WO2005018988A1; GB0418093D0; GB0319423D0; GB0524268D0

Abstract

A vehicle lamp comprises a plurality of light emitting devices which are capable of emitting light at two or more wavelengths. A control unit controls the light emitting devices to emit light at a particular wavelength in dependence on one or more input signals which are generated by switches within the vehicle, such as an indicator switch, a brake pedal switch or a reverse gear switch. The lamp is capable of providing two or more signalling functions simultaneously, or a single signalling function, as desired by controlling individually the colour emitted by each light emitting device. The lamp is capable of providing specific control instructions if one or more of the LEDs fails to maintain the overall appearance of the lamp.

Description

LAMP

The present invention relates to a lamp and particularly, but not exclusively, to a combined brake and indicator lamp for a vehicle such as an automobile.

All automobiles are provided with a plurality of warning lamps, particularly at the rear of the vehicle, for providing a warning to other drivers of the vehicle's movements or the driver's intentions. Conventionally, such rear warning lamps consist of a plurality of bulbs or other light emitting devices contained in a housing known as a "cluster". Each cluster usually comprises at least one bulb for use as a brake lamp which illuminates when the driver presses the brake pedal, at least one bulb for use as a reversing lamp, which illuminates when the driver selects reverse gear and at least one bulb for use as an indicator lamp, which flashes when an indicator switch is actuated by the driver.

Conventionally, therefore, each cluster has three separate lamps, each of which is connected to a different switch within the vehicle and is independently operable (each lamp can be actuated independently of the other lamps).

Furthermore, each lamp is used for only one specific function and each of the lamps are a different colour. The vehicle is usually provided with two such clusters, located on the left and right sides, respectively, of the rear of the vehicle.

Many vehicles are also provided with a so-called high-level brake lamps, which are conventionally located between the left and right lamp clusters at the rear of the vehicle, either at the top of the rear windscreen or within a spoiler or other aerodynamic or aesthetic device that is fitted to the vehicle. Such lamps generally consist of a plurality of bulbs or LEDs connected in parallel to the same circuit to which the conventional brake lamps are connected. None of the bulbs is independently operable and all are arranged to emit red light when the brake pedal is depressed by the driver. The purpose of the high-level brake lamp is to provide a more visible warning to other drivers that the vehicle is braking.

A disadvantage of both the conventional lamp clusters and the high-level brake lamp is that each bulb or LED can only be used for a single purpose, i.e. to warn of one vehicle condition or "mode", such as braking, reversing, indicating etc. If that condition or mode is not occurring at any given moment, the bulb relating to that mode is redundant and cannot be used to indicate other conditions or modes even if they are occurring.

Additionally, conventional lamp clusters suffer the problem that each bulb included therein is connected to a different, and electrically separate, circuit within the vehicle. There are therefore a large number of wires or conductors which must be provided from the different switches within the vehicle and routed to the lamp clusters.

Furthermore, to ensure that light from one bulb does not interfere with that from another bulb, each bulb must be separated by means of partitions within the cluster housing, increasing the complexity and cost thereof.

It is an aim of the present invention to address the above and other disadvantages.

According to one aspect of the present invention, therefore, there is provided a lamp for a vehicle comprising at least one light emitting device arranged selectively to emit light at a first wavelength and at a second wavelength, in response to at least one signal applied thereto.

Each of the first and second wavelengths may represent a different condition or mode of the vehicle.

The lamp may comprise a plurality of light emitting devices, each of which is arranged selectively to emit light at the first and the second wavelengths.

The or each light emitting device may arranged to emit light at three or more wavelengths.

The wavelength of the light emitted by the or each light emitting device may be independent of the wavelength of the light emitted by any other light emitting devices.

According to another aspect of the invention there is provided a lamp system for a vehicle comprising a lamp as described in any of the preceding paragraphs and control means for generating a first signal and applying the first signal to at least one light emitting device.

The or each light emitting device to which the first signal is applied may be r arranged to emit light at the first wavelength in response thereto.

The control means may be arranged to generate a second signal and apply the second signal to at least one light emitting device.

The or each light emitting device to which the second signal is applied may be arranged to emit light at the second wavelength in response thereto.

The control means may be arranged to generate the first signal in response to operation of a first switch connected thereto.

The control means may be arranged to generate the second signal in response to operation of a second switch connected thereto.

The control means may comprise a processor arranged to sense operation of one or more switches and to generate a control signal in response thereto.

The control signal may be a binary control signal.

The system may further comprise driver means arranged to receive the control signal and to generate and apply the first or second signals to the or each light emitting device in dependence on the control signal.

The driver means may be arranged to generate and apply the first or second signal to one light emitting device independently of the other light emitting devices.

The system may further comprise detection means for detecting whether one or more light emitting devices has failed or is operating incorrectly and generating an error signal in response thereto.

The processor means and/or the driver means may be arranged to receive the error signal and to alter the signals applied to the or each light emitting device in dependence thereon.

The present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 illustrates the position of conventional warning lamps on a vehicle; Figure 2 is a schematic block diagram of a circuit for the warning lamps of Figure 1; Figure 3 is a schematic block diagram of a first form of lamp according to the invention; Figure 4 is a matrix illustrating operation of the lamp of Figure 3; and Figure S is a schematic block diagram of an alternative form of system according to the invention.

Referring firstly to Figure 1, a vehicle having a plurality of warning lamps is shown generally at i0. The vehicle 10 has left and right lamp clusters 12a, 12b and a high mounted brake lamp 14. The left lamp cluster 12a comprises a housing 13a, mounted to the vehicle 10, within which three bulbs 15a, 16a, 17a, are located. The right lamp cluster 12b similarly has three bulbs lSb, 16b, 17b located in a housing 13b. In some instances other light emitting devices, such as LEDs, are used but in the following description the term "bulb" will be used for convenience. Also for convenience, operation of only the left hand cluster 12a will be described but it will be appreciated that the right hand cluster 12b operates in a similar manner and contemporaneously with the left *' i hand cluster.

Each bulb 15a, 16a, 17a is mounted in a separate part of the housing 13 and is covered by a window or lens of translucent material, usually a plastics material.

Since each bulb lSa, 16a, 17a is clear and is arranged to generate white light, the lenses covering each bulb are coloured in the relevant colour for the purpose for which the bulb is intended. The cluster 12a thus defines three separate lamps, each of which is operable or actuable in response to the operation of a respective switch within the vehicle 10.

For example, the first bulb 15a is arranged to operate in response to actuation of a switch connected to the brake pedal of the vehicle. Closing of this brake pedal switch allows a current from the vehicle battery to flow through the bulb 15a causing it to illuminate or glow. The first bulb 15a is covered by a lens which is red in colour so that the visible effect of pressing the brake pedal is that of a red light glowing.

The second bulb 16a is arranged to operate in response to selection of reverse gear in the vehicle's transmission, which action closes a reverse gear switch.

Closing of the reverse gear switch allows a current from the battery to flow through the second bulb 16a causing it to illuminate. The second bulb 16a is covered by a lens which is white or clear in colour so that the visible effect from the rear of the vehicle when reverse gear is selected is that of a white light glowing.

Finally, the third bulb 17a is arranged to flash in response to operation of an indicator switch on the vehicle. Closing of the indicator switch allows a current from the battery to flow through the second bulb 17a causing it to illuminate.

The second bulb 17a is covered by an orange lens so that the visible effect from the rear of the vehicle when the indicator switch is actuated is that of an orange light flashing.

The high-level brake lamp 14 is comprised of a number of bulbs 18 connected in parallel and are arrange to operate in response to actuation of the brake pedal switch in the same manner as the first bulb 15a in the lamp cluster 12a. Thus when the brake pedal switch is closed, i.e. when the brake pedal is depressed, current flows from the vehicle battery through each of the bulbs 18 causing them to illuminate. The bulbs 18 are covered by a red lens so that the visible effect from the rear of the vehicle is that of a red light glowing. In many high- level brake lamps, the bulbs 18 are, in fact, red LEDs which themselves emit red light. In these cases, therefore, a clear lens is possible.

The lamp cluster 12a thus effectively defines three separate warning lamps, a brake lamp, reversing lamp and indicator lamp. The high-level brake lamp 14 is physically separate but is electrically connected to the brake lamp in the cluster 12a.

Figure 2 illustrates the electrical connections to each of the lamps 15a, 16a, 17a in the lamp cluster 12a.

The first bulb 15a, representing the brake lamp, is connected to the vehicle battery via the brake pedal switch 20. When the brake pedal switch 20 is closed, i.e. when the brake pedal is depressed, current flows from the vehicle battery through the first bulb 15a causing it to illuminate. As described above, the lamp glows red owing to the red lens covering the bulb.

Similarly, the second bulb 16a, representing the reversing lamp, is connected to the vehicle battery via the reverse gear selection switch 22. When the reverse gear selection switch 22 is closed, i.e. when reverse gear is selected by the driver, current flows from the vehicle battery through the second bulb 16a causing it to illuminate. As described above, the lamp glows white owing to the white lens covering the bulb.

The third bulb 17a representing the indicator lamp, is connected to the vehicle battery via a controller 24 and an indicator switch 26. When the indicator switch 26 is closed, i.e. when it is actuated by the driver, a pulsed current flows from the controller 24 through the third bulb 17a causing it to flash. As described above, the lamp flashes orange owing to the orange lens covering the bulb.

Finally, the bulbs or LEDs 18 forming the high-level brake lamp 14 are connected in parallel across the first bulb 15a. Thus, when the brake pedal switch 20 is closed, current flows from the vehicle battery through the LEDs 18 causing them to illuminate.

As described above, the bulbs 15a, 16a, 17a, and the LEDs 18, are each connected to a different electrical circuit within the vehicle 10 and as the colour of each lamp is determined by the colour of the lens covering the bulb, which is fixed, each lamp can only be used to signify one vehicle mode, i.e. braking, reversing or indicating respectively. If one vehicle mode does not occur, the respective lamp is not used and becomes temporarily redundant.

Figure 3 is a schematic block diagram of a first form of warning lamp system according to the invention. The lamp system, referred to generally at 30, comprises a lamp 32 having an elongate housing 33. In this embodiment, the lamp 32 is intended to replace the high-level brake lamp 14 shown in Figure 1.

The length of the housing 33 in this embodiment is such that it extends almost fully across the width of the vehicle, although any length or size can be employed.

The housing can be mounted at the top of the rear windscreen of the vehicle or -t within a spoiler or other aerodynamic or aesthetic device fitted to the rear of the vehicle, as in the case of the high-level brake lamp 14. However, it will be appreciated that the principle of the invention can also be applied to the left and right lamp clusters as well as any other lamps on the vehicle.

The lamp 32 comprises a plurality of light emitting devices 34 in the form of LEDs mounted within the housing 33. In the illustrated embodiment, the lamp 32 consists of 12 LEDs L1 - L12 mounted in alignment within the housing 33.

The arrangement is such that the LEDs define, in use, a substantially horizontal row.

Each LED 34 is arranged to emit light in three different colours. Such LEDs, which are known as tri-coloured LEDs, are designed to emit light of different wavelengths (colours) in dependence on the polarity and/or magnitude of a voltage applied thereto. For example, if a voltage of, say, +1.5 volts is applied to the LED, it emits red light; if a voltage of +3 volts is applied to the LED, it emits orange light; or if a voltage of -1. 5 volts is applied to the LED, it emits white light.

Such tri-colour LEDs, and similar LEDs which emit only two colours or which emit more than three colours (known as bi-colour and multi-colour LEDs, respectively), are well known and further detail of their construction and operation is not included herein. It will be understood, however, that the above paragraph is intended to be representative only of the operation of tri-colour LEDs and that actual voltages which must be applied to the LED in order to produce the red, orange and white light described above may differ from those described and will depend on the type or manufacturer of the LED. In particular, such LEDs frequently include three or more electrodes, rather than the two represented in Figure 3, and the colour emitted by the LED may depend on the voltages across each of the electrodes.

However, the present description is intended to illustrate the principle of operation of the lamp 32 and therefore the above mentioned voltages are hereafter referred to for convenience but are not intended to be limiting in any way.

One electrode of each LED 34 in the housing 33 is individually connected to a respective output of a driver unit 36. The other electrode of each LED is connected to the vehicle earth 38. The driver unit 36 is arranged to generate voltages of different magnitudes and polarities on each output and apply these voltages to each of the LEDs. Each output from the driver unit 36 is substantially independent and thus the driver unit 36 is able to apply different voltages to different LEDs at the same time.

In the exemplary embodiment, the driver unit 36 is arranged selectively to apply three different voltages, that is to say the +1.SV, +3V and -1. 5V voltages described above, to each of the LEDs 34. As described above, the colour emitted by a given LED 34 is dependent upon the voltage applied thereto by the driver unit 36.

An input of the driver unit 36 is connected to an output of a control unit or processor 40 which is arranged to generate a control signal, in binary, in dependence on input signals applied to a plurality of inputs thereof. The processor 40 applies the binary control signal to the driver unit 36 which generates the relevant voltage for each LED in dependence thereon using a simple matrix.

The processor 40 is provided with five inputs It - I5, each of which is connected to a respective switch of the vehicle. A first one of the inputs I1 is connected to the left hand indicator switch 26a which, when actuated (closed), causes a voltage to be applied thereto. The second input I2 is connected to the right hand indicator switch 26b which, when actuated (closed), causes a voltage is applied thereto.

Similarly, the third input IS is connected to the brake pedal switch 20, actuated when the brake pedal is depressed, the fourth input I4 is connected to the vehicle's hazard warning switch 42 and the fifth input 15 is connected to the reverse gear switch 22, actuated when reverse gear is selected. On actuation (closing) of each of these switches, a voltage is applied to the respective input of the processor. If a switch is not actuated, i.e. it is left open, no voltage is applied to the respective input. The inputs are thus effectively either at a "high" state, when a voltage is applied thereto, or at a "low" state, when no voltage is applied thereto.

The processor 40 is arranged to detect whether each input is at a high or a low state and to generate a binary control signal accordingly. The control signal is applied to the input of the driver unit 36 which generates and applies the required voltages to each of the LEDs 34 in the lamp.

Referring to Figure 4, this illustrates operation of the system of Figure 1. It can be seen that the LEDs 34 in the lamp are arranged to generate different patterns depending on the status of each of the switches 20, 22, 26a, 26b, 42.

There are at least fifteen combinations which are possible from the five switches during normal operation of the vehicle, in addition to all LEDs off, giving at least fifteen combinations of high/low status for the inputs of the processor 40 and hence fifteen binary control signals which must be generated by the processor 40. Examples of these combinations are illustrated in the first table of Figure 4 where a "1" represents a high input, i.e. the respective switch is actuated (closed) so that a voltage is applied to the input, and a "O" represents a low, i.e. the respective switch is not actuated (open) so that no voltage is applied to the input. The second table in Figure 4 illustrates the colour emitted by the LEDs 34 for each combination.

Combination one represents the mode when the vehicle is indicating left. In this mode, the left hand indicator switch 26a is actuated such that the first input I1 is at 1 whilst the remaining inputs are at 0. The processor 40 detects the combination of Is and Os and generates a binary control signal of 16 accordingly.

The control signal is applied to the driver unit 36 which generates and applies the relevant voltages to the LEDs 34 using the matrix. Specifically, the driver unit 36 applies a voltage of +3V to LEDs L1 to L3 which therefore emit orange light, as described above. Moreover, the voltage in this case alternates between +3V and OV at a predetermined frequency so that LEDs L1 to L3 flash orange.

The remaining LEDs remain in an off state.

Combination two represents the mode when the vehicle is indicating right. In this mode, the right hand indicator switch 26b is actuated such that the second input I2 is at 1 whilst the remaining inputs are at 0. The processor 40 detects the combination of Is and Os and generates a binary control signal of 8 accordingly.

The binary control signal is applied to the driver unit 36 which generates and applies the relevant voltages to the LEDs 32 using the matrix. Specifically, the driver unit applies a voltage of +3V to LEDs L10 to L12 which therefore emit orange light, as described above. Again, the voltage alternates between +3V and OV at a predetermined frequency so that LEDs L10 to L12 flash orange.

The remaining LEDs remain in an off state.

Combination three represents the mode when the vehicle is braking. In this mode, the brake pedal switch 20 is actuated such that the third input I3 is at 1 whilst the remaining inputs are at 0. The processor 40 detects the combination of Is and Os and generates a binary control signal of 4 accordingly.

The control signal is applied to the driver unit 36 which generates and applies the relevant voltages to the LEDs 32. Specifically, the driver unit applies a voltage of +1.SV to all of the LEDs L1 to L12 which therefore emit red light, as described above. The LEDs L1 to L12 continue to emit the red light for as long as the fourth input to the processor is at 1. When the fourth input returns to O. i.e. when the brake pedal is released, the processor 40 sends a reset signal to the driver unit 36 which no longer applies a voltage to the LEDs.

Combination four represents the mode when the hazard warning switch 42 has been actuated such that the fourth input is at 1 whilst the remaining inputs are at 0. The processor 40 detects the combination of Is and Os and generates a binary control signal of 2 accordingly.

The control signal is applied to the driver unit 36 which generates and applies the relevant voltages to the LEDs 34. Specifically, the driver unit applies a voltage of +3V to LEDs L1 to L3 and L10 to L12 which therefore emit orange light, as described above. As in the case of combinations one and two, the voltage generated by the driver unit and applied to LEDs L1 to L3 and L10 to L12 alternates between +3V and OV at a predetermined frequency so that the LEDs flash orange. The remaining LEDs remain in an off state.

Combination five represents the mode when the vehicle is reversing. In this mode, the reverse gear switch 22 is actuated such that the fifth input is at 1 whilst the remaining inputs are at 0. The processor 40 detects the combination of Is and Os and generates a binary control signal of 1 accordingly.

The control signal is applied to the driver unit 36 which generates and applies the relevant voltages to the LEDs 34. Specifically, the driver unit applies a voltage of -1.5V to all of the LEDs L1 to L12 which therefore emit white light, as described above.

Combination six represents the mode when the vehicle is braking and indicating left. In this mode, the brake pedal switch 20 is actuated, as in the third mode, and the left hand indicator switch 26a is actuated, as in the first mode. The processor 40 detects the combination of Is and Os at the inputs thereof and generates a binary control signal of 20 accordingly.

The control signal is applied to the driver unit 36 which generates and applies the relevant voltages to the LEDs 34. Specifically, the driver unit generates a voltage which alternates between OV and +3V and applies this pulsed voltage to the LEDs L1 to L3 which therefore flash orange, as described above. In addition, the driver unit generates and applies a voltage of +1.5V to the LEDs numbers L4 to L12 which therefore glow red.

Similarly, in combination seven, which represents the mode in which the vehicle is braking and indicating right, the processor detects the combination of Is and Os at it inputs and generates a binary control signal of 12 which causes the driver unit 36 to generate and apply the relevant voltages to the LEDs 34.

Specifically, the driver unit 36 generates a voltage which alternates between OV and +3V and applies this pulsed voltage to LEDs L10 to L12 which therefore flash orange, as described above. In addition, the driver unit 36 generates and applies a voltage of +1.SV to LEDs numbers L1 to L9 which therefore glow red.

Combinations eight and nine represent, respectively, the modes where the vehicle is reversing and indicating left or right. In these modes, the processor detects the combination of Is and Os at its inputs, and generates a binary control signal of 17 or 9, respectively, which is applied to the driver unit 36.

The driver unit applies a voltage which alternates between OV and +3V to LEDs L1 to L3, which causes them to flash orange, and a voltage of -1.5V to LEDs L4 to L12, which causes them to glow white (in the eighth mode) or a voltage which alternates between OV and +1.5V to LEDs L10 to L12, which causes them to flash orange, and a voltage of -1.5V to LEDs L1 to L9, which causes them to glow white (in the ninth mode).

Combinations ten and eleven represent the condition where the vehicle is reversing, braking and indicating either left or right. In these modes, the processor detects the combination of Is and Os at its inputs and generates a binary control signal of 21 or 13, respectively, which is applied to the driver unit 36.

In combination ten, the driver unit 36 applies a voltage which alternates between OV and +3V to LEDs L1 to L3, which causes them to flash orange, a voltage of +3V to LEDs L4 to L9 which causes them to glow red and a voltage of-1.SV to LEDs L10 to L12, which causes them to glow white.

In combination eleven, the driver unit 36 applies a voltage which alternates between OV and +3V to LEDs L10 to L12, which causes them to flash orange, a voltage of +3V to LEDs L4 to L9 which causes them to glow red and a voltage of-1.SV to LEDs L1 to L3, which causes them to glow white.

Combination twelve represents the mode in which the vehicle is reversing, braking and has its hazard warning lamps on. Here, the processor 40 detects the combination of Is and Os at its inputs and generates a binary control signal of 7 accordingly which is applied to the driver unit 36.

The driver unit 36 generates and applies a voltage which alternates between OV and +3V to LEDs Llto L3 and L10 to L12, which causes them to flash orange, a voltage of +1.SV to LEDs L4, LS, L8 and L9, which causes them to glow red, and a voltage of -1.SV to LEDs L6 and L7, which causes them to glow white.

Combination thirteen represents the mode in which the vehicle is reversing and has its hazard warning lamps on. In this mode, the processor 40 detects the combination of Is and Os at its inputs and generates a binary control signal of 3 accordingly which is applied to the driver unit 36.

The driver unit 36 generates and applies a voltage which alternates between OV and +3V to LEDs L1 to L3 and L10 to L12, which causes them to flash orange and a voltage of -1.SV to LEDs L4 to L9, which causes them to glow white.

Combination fourteen represents the mode in which the vehicle is braking and has its hazard warning lamps on. In this mode, the processor 40 detects the combination of Is and Os at its inputs and generates a binary control signal of 6 accordingly which is applied to the driver unit 36.

The driver unit 36 generates and applies a voltage which alternates between OV and +3V to LEDs L1 to L3 and L10 to L12, which causes them to flash orange and a voltage of +1.5V to LEDs L4 to L9, which causes them to glow red.

Finally, combination fifteen represents the mode in which the vehicle is both reversing and braking. In this mode, the processor 40 detects the combination of Is and Os at its inputs and generates a binary control signal of S accordingly which is applied to the driver unit 36.

The driver unit 36 generates and applies a voltage of -1.5V to LEDs L1 to L3 and L10 to L12, which causes them to glow white and a voltage of +1.SV to LEDs L4 to L9, which causes them to glow red.

It will be appreciated that the selection of which LEDs are illuminated for each condition or mode is a matter of choice. Since each LED 34 is capable of emitting light at two or more colours, it is merely a matter of programming the processor and driver unit, or generating the relevant matrix, to ensure that the appropriate voltages are generated and applied to the required LEDs in order to display the desired pattern.

It will also be appreciated that the invention is not limited only to indicator, brake and reversing lamps. Indeed, many vehicle light clusters additionally feature driving lamps and fog lamps and it is possible to incorporate these lamp functions into the lamp of the invention.

The number and arrangement of LEDs 34 can be selected as desired. In the embodiment of Figures 3 and 4, there are 12 LEDs which are aligned in a substantially horizontal row, in order to be positioned at the top of therear windscreen or within a rear spoiler. However, the system of the invention can be used to replace the conventional lamp clusters in which case the LEDs might be arranged in a two-dimensional shape or matrix, as illustrated in Figures Sa and Sb.

In Figure Sa, there are twenty four LEDs arranged in three concentric circles.

Where a combination of three lamps is required, for example in modes 10 to 12, the outer circle of LEDs can be illuminated for the brake lamp, the middle circle can be illuminated for the indicator lamp and the inner circle can be illuminated for the reversing lamp.

Where a combination of two lamps is required, the outer circle of LEDs can be illuminated for one lamp function and the remaining LEDs can be illuminated for the other function. Where only one function is required all, or just some, of the LEDs can be illuminated.

Similar considerations apply to the rectangular arrangement of Figure Sb. In both embodiments, however, the selection of which LEDs are illuminated for each lamp function is one of choice.

It will be appreciated that various improvements or modifications might be made to the invention. For example, means may be provided for monitoring whether all of the LEDs are functioning correctly and for detecting if one or more LEDs fails. In this embodiment, if the detection means detects that one or more of the LEDs is operating incorrectly or has failed, it sends a signal to the processor indicating the LEDs concerned and the processor controls the driver unit to alter or adjust the pattern displayed for each condition or mode.

For example, in the event of failure of an individual LED in a row or block, the processor is arranged selectively to switch off a corresponding functional LED so as to maintain an aesthetically pleasing appearance of the lamp. Considering Figure 4, for example, were LED L4 to fail, the appearance of the lamp would be compromised, the failed LED being clearly noticeable.

In the invention, however, the processor may, in this case, automatically switch off or deactivate LED L9 which corresponds symmetrically to LED L4. Thus, a symmetrical appearance of the lamp is maintained and the failed LED will be undetected by the driver or other road users, thereby maintaining the perceived quality of the lamp. The processor may determine the most appropriate functional LEDs to deactivate in order to maintain the aesthetically pleasing appearance of the lamp in dependence on the position and/or number of the failed LEDs. The processor may employ fuzzy logic or the like for this purpose.

This is particularly advantageous if a number of LEDs fail simultaneously. In this case, there will be no loss of lamp function since if all of the LEDs fail which normally operate to form, say, the reversing lamp, some of the remaining LEDs can be used to perform that lamp function. In conventional lamp clusters, failure of a bulb results in the loss of the relevant lamp function requiring immediate replacement of the bulb. In the present invention, replacement of the failed LEDs can be deferred until routine servicing of the vehicle, saving expense and inconvenience.

In addition, it is possible for the patterns used for each mode to be selected by the driver. In this embodiment, means are provided for programming the processor and driver unit by the driver. This can be achieved by a vehicle control panel or Human Machine Interface (HMI). This allows an element of customization to be included with the vehicle.

Although the described embodiment employs microprocessor controlled switching of the LEDs, it will be appreciated that conventional switching technology, such as relays, solid state devices or a standard switching matrix could alternatively be employed.

In the described embodiment, all of the LEDs are tri-colour LEDs.

Alternatively, however, bi-colour LEDs could be used, where only two colours are required, such as in a combined indicator and brake lamp with no reversing lamp function, or mulit-colour LEDs where additional lamp functions are required.

It will be understood that both the processor 40 and the driver unit 36 require a power supply. This is not shown in the drawings but an advantage of the invention is that only a single power supply to the entire system is required. All of the vehicle switches 20, 22, 26a, 26b, 42 can be connected to the processor by a single, multi-core cable, reducing wiring complexity and cost.

In one embodiment, the LEDs are not individually operable. Instead, the LEDs are grouped in "banks" which, although capable of emitting two or more colours, are arranged always to emit the same colour. For example, in Figure 3, LEDs L1 to L3 might represent a first group, LEDs L4 and LS a second group, LEDs L6 and L7 a third group, LEDs L8 and L9 a fourth group and LEDs L10 to L12 a fifth group. These groups are selected since the LEDs concerned always operate together and emit the same colour. Alternative groupings can be utilised where desired, however. This option may be less costly to manufacture but reduces flexibility of the system.

It will be understood by those skilled in the art that control of the LEDs may be achieved by the use of Pulse Width Modulated digital signals generated by the processor 40. This permits greater resolution in the control of the LEDs enabling the varying in intensity of the light and/or the varying of the voltage applied thereto in order to achieve different colours.

It will be appreciated that the present invention provides a much improved lamp and lamp system for a vehicle which exhibits a number of advantages over existing systems including reduced cost and installation complexity, flexibility and improved redundancy.

Claims

1. A lamp for a vehicle comprising at least one light emitting device arranged to emit light at a first wavelength and at a second wavelength, in response to at least one signal applied thereto.

2. A lamp as claimed in claim 1 wherein each of the first and second wavelengths represents a different condition or mode of the vehicle.

3. A lamp as claimed in claim 1 or claim 2 comprising a plurality of light emitting devices, each of which is arranged to emit light at the first and the second wavelengths.

4. A lamp as claimed in any preceding claim wherein the or each light emitting device is arranged to emit light at three or more wavelengths.

5. A lamp as claimed in any preceding claim wherein the wavelength of the light emitted by the or each light emitting device is independent of the wavelength of the light emitted by any other light emitting devices.

6. A lamp system for a vehicle comprising a lamp as claimed in any preceding claim and control means for generating a first signal and applying the first signal to at least one light emitting device.

7. A system as claimed in claim 6 wherein the or each light emitting device to which the first signal is applied emits light at the first wavelength in response thereto.

8. A system as claimed in claim 6 or claim 7 wherein the control means is arranged to generate a second signal and apply the second signal to at least one light emitting device.

9. A system as claimed in claim 8 wherein the or each light emitting device to which the second signal is applied emits light at the second wavelength in response thereto.

10. A system as claimed in any of claims 6 to 9 wherein the control means is arranged to generate the first signal in response to operation of a first switch connected thereto.

11. A system as claimed in any of claims 6 to 10 wherein the control means is arranged to generate the second signal in response to operation of a second switch connected thereto.

12. A system as claimed in any of claims 6 to 11 wherein the control means comprises a processor arranged to sense operation of one or more switches and to generate a control signal in response thereto.

13. A system as claimed in claim 12 wherein the control signal is a binary control signal.

14. A system as claimed in claim 12 or claim 13 further comprising driver means arranged to receive the control signal and to generate and apply the first or second signals to the or each light emitting device in dependence on the control signal.

15. A system as claimed in claim 14 wherein the driver means is arranged to generate and apply the first or second signal to one light emitting device independently of the other light emitting devices. b

16. A system as claimed in any of claims 6 to 15 further comprising detection means for detecting whether one or more light emitting devices has failed or is operating incorrectly and generating an error signal in response thereto.

17. A system as claimed in claim 16 wherein the processor means and/or the driver means is arranged to receive the error signal and to alter the signals applied to the or each light emitting device in dependence thereon.