This invention relates to a device providing backlight of various colours on the instrument panel display, more pariicularly, the LCD (liquid crystal display) or analog dislay of a motor vehicle.
instrument dusters are used on instrument panels for displaying vehrde information, such as, vehicle speed, fuel level, and engine rpm, among other par^culars. These clusters can be Implemented digltatty, LCD panels being used for the purpose. Generally, several LED's of a single colour are used for this purpose and the backfight of the LCD is also of a single colour and cannot be changed after installation.
The device proposed herein has RGB LEDs, that is, red, green and blue LEDs, for providing red, green and blue coloured lights as the backlight or a combination of these cofours by superimposition of colours. Such change in

colours can be attained trom time to time depending upon the information supplied to the instrument panel Such a provision will not only add to the aesthetic Value of the instrument cluster but also give cautionary indications to the user, for example, about the speed of the vehicle, throttle control, battery charge condition and so on (hereinafter called the performance information).
hi other words, this invention provides vital performance infonnation to the vehicle user about various particulars of engine performance just by making a quick note of the change in the backlight colour of the instrument panel. For example a variation of speed from low to high can be indicated in a strip on the instalment panel as a color variation from yellow to red and vice versa . A fall in level of petrol in the fuel tank can be indicated in another strip by a change in

colour from blue to orange. So also when the fuel tank is refilled with petrol the colour can be made to change from orange to blue.
The device for providing backlight of different colours on the liquid crystal display or analog display instrument pane) of a motor vehicle, according to this invention, comprises electronic control means; at least one sensor for feeding at least one signal, based on performance information to the input of the electronic control means, at least one RGB LED located on the instrument panel of the vehicle and connected to the outpiA of ^e electronic control means, the said signal activating the electronic control means to control the cun-ent through, and thus trigger, the LED or LEDs singly or jointly, for illuminating the instrument panel with various colours determined by the electronic control means.
This invention will be described with reference to the accompanying drawings in which the single Figure illustrates, by way of example and not by

way of limitation, one of possible embodiments of the device proposed herein. The visible spectrum of light comprises colours ranging from violet to red. Out of these colours, three are classified as fundamental colors, namely red, blue and green. All other combinations of colours can be created using mixing different proportions of these primary colors.
This invention proposes to use RGB LEDs to create various colors for a backlight of an LCD in automotive applications. The RGB LEDs consist of three LEDs, which emit three fundamental colors of light.
Thus by varying the intensity of Ught emitting from individual LEDs the RGB LEDs can create a wide variety of colors in the visible spectrum. The intensity of individual LEDs are a function of average current through it. These currents can

be controlled by Pulse Width Modulation of varying ratio.
The circuit incorporates a microcontroller M. The input signals S and T, such as, those relating to speed, throttle position and so on relate to performance information which will be used by the microcontroller M to determine the colour or colours of the back hght of the LCD. The three digital output ports P1 P2 P3 of the microcontroller are connected to R, G and B temiinals of RGB LEDs.
The microcontroller applies varying PWM signals to these three digital output ports to get the desired colours depending on different input conditions.
It will be appreciated that various other embodiments are possible without departing from the scope and ambit of this invention.

We Claim:
1. A device for providing backlight of different colours on the liquid crystal display or analog display of the instrument pane) of a motor vehicle comprising electronic control means; at feast one sensor for feeding at (east one signal, based on performance informalion to the input of the electronic control means, at ieast one RGB LED located on the instrument panel of the vehicle and connected to the output of the electronic control means, the said signal activating the electronic control means to control the current through, and thus trigger, the LED or LEDs singly or jointly, for illuminating the instrument panel with vahous colours determined by the eiectronic control means.
2. A device as claimed in Claim 1, wherein the electronic control means consist of a micro controller.

3. A device as claimed in claim 1, wherein the electronic control
means consist of a field programmable gate array.
4. A device as claimed in Ciaim 1, wherein the electronic
control means consist of a programmable logic device.
5. A device for providing backlight of different colours on the
liquid crystal display or analog display of the instrument
panel of a motor vehicle substantially as herein described
and illustrated in the accompanying drawings.