The present invention relates to a Light Emitting Diodes (LEDs) based illumination system for vehicular application such as two-wheeler, bike, motorbike, scooter and the like.
BACKGROUND OF THE INVENTION:
The two-wheeler vehicle such as bike, motorbike, scooter and the like comprises a position light, left & right winkers at the front, left & right winkers at the rear, an illumination light located near the rear license plate and a tail stop light associated with brakes.
In the prior art, the said lights incorporate incandescent bulbs. But as the automobile industry is evolving and moving towards replacing incandescent bulbs with the light emitting diodes for the fact that LED has an extremely long lifespan and are energy efficient as compared to any other lighting technology. The replacement of incandescent bulbs with LED necessitates some additional components such as buck/boost converter, current driver, power controller and the like.
By way of example, E.P. Patent no. 2538753 discloses a driver device for light-emitting diodes, comprising: - a controllable first power source configured to produce a first voltage at its output and a buck converter having an input coupled to the output of said first power source, and an output for coupling light-emitting diodes thereto. Further, the E.P. Patent discloses that same principle can be applied in cases where there are multiple buck converters that all receive their input voltages from a common controllable first power source. In such a case it may happen that different numbers of serially coupled LEDs are driven by different ones of the buck converters.
By way of example, Non- Patent Literature "LED Controllers and Switches Improve Matrix Lighting" as may be downloaded from https://www.planetanalog.com/author.asp7section id=3406&doc id=565004 discloses a led driving circuit with multiple buck converters. It has been felt that the use of multiple buck converters will increase the cost.
By way of example, U.S. Patent No. 20040155844 discloses a driver circuit for energizing a plurality of LEDs, said driver circuit comprising: a constant current source responsive to a first input to produce a current and connectable to an emitter comprising a plurality of LEDs,

said constant current source configured to monitor an electrical current through the plurality of LEDs and limit said current to said current; a controller programmed to; monitor the state of a synchronization input to the controller; provide said first input to said constant current source in a predetermined pattern, initiation of said pattern alternatively controlled by the controller or by a change of state of said synchronization input; and produce a synchronization output indicating initiation of said pattern by said controller; and a synchronization circuit electrically connected to a synchronization line, said synchronization circuit responsive to a change in the electrical potential present on the synchronization line from a first electrical potential to a second electrical potential to provide said synchronization input to the controller and responsive to said synchronization output from the controller to apply said second electrical potential to said synchronization line, wherein initiation of said pattern is triggered by the change of electrical potential on the synchronization line if said synchronization input is present before the controller produces said synchronization output and initiation of said pattern by said controller is triggered by the controller if said synchronization input is not present before the controller produces said synchronization output.
Thus, it has been felt that the existing LED-based illumination system suffers from several disadvantages including high cost, large size, increased complexity, high heat dissipation etc. Therefore, a simpler and cost-efficient LED-based illumination system is required.
SUMMARY OF THE INVENTION:
This summary is provided to introduce a selection of concepts in a simplified format that is further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.
Accordingly, the present invention provides a LED-based illumination system for vehicular application, said illumination system comprising: a power controller (106) connected between a battery or power supply device (102) and aplurality of LED-based devices (104i
n), the power controller (106) being configured to receive the input voltage from the
battery or power supply (102) and provide constant driving currents for illuminating each of
the plurality of the LED-based devices (104i n).

In an embodiment of the invention, the power controller (106) comprises: a buck converter (114) configured to receive the input voltage and generate a preconfigured driving voltage;
and a plurality of driver circuits (1161 n) connected in parallel to each other and to an
output of the buck converter (114), each of the plurality of driver circuits (1161 n) being
configured to receive the preconfigured driving voltage as produced by the buck converter
(114) and generate the preconfigured constant current for driving the plurality of LED-based
devices (104i n).
In an embodiment of the invention, the power controller (106) comprises a capacitor (118) to act as a backup in an event of non-availability of input voltage from the battery or power supply device (102).
In another embodiment of the invention, the power controller (106) further comprises a reverse protection device (120) provided in the path between the battery (102) and the capacitor (118).
In still another embodiment of the invention, the power controller (106) further comprises a
plurality of diodes connected after a junction terminal (JT), the junction terminal being
located between the buck converter (114) and the plurality of current drivers (116i n).
In a further embodiment of the invention, the power controller (106) comprises a plurality of
diodes connected between the junction terminal (JT) and the input of each of the current
driver (116i n).
In a furthermore embodiment of the invention, the power controller (106) comprises a plurality of diodes connected at about the output terminal of each of the current driver
(H6l n).
To further clarify the advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:
These and other features, aspects, and advantages of the present invention will become better
understood when the following detailed description is read with reference to the
accompanying drawings in which like characters represent like parts throughout the
drawings, wherein:
Figure 1 demonstrates a first circuit (100) for providing a constant current to a plurality of
LED-based devices incorporated in a two-wheeled vehicle in accordance with an
embodiment of the invention;
Figure 2 demonstrates the circuit of Figure 1 with wire harness short to battery/power supply
condition in accordance with an embodiment of the invention;
Figure 3 demonstrates a second circuit (200) for providing a constant current to a plurality of
LED-based devices incorporated in a two-wheeled vehicle in accordance with an
embodiment of the invention; and
Figure 4 demonstrates a third circuit (300) for providing a constant current to a plurality of
LED-based devices incorporated in a two-wheeler vehicle in accordance with an embodiment
of the invention.
Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present invention. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
DETAILED DESCRIPTION OF FIGURES
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated

system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the invention and are not intended to be restrictive thereof.
Reference throughout this specification to "an aspect", "another aspect" or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises... a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
Referring to Figure 1, it can be observed that a vehicle may comprise a first circuit (100) which may comprise a power controller (106) connected between a battery or power supply
device (102) and a plurality of LED-based devices (104i n). A first wire set (108) provides
a connection between the battery (102) and the power controller (106). In an embodiment, the

power supply device may include a combination of ACG and regulator/rectifier. Likewise, a
second wire set (llOi n) connects the power controller (106) and each of the LED-based
devices (104i n). Further, a third wire set (112i n) provides ground connections. The first
wire set (108) the second wire set (llOi n), and the third wire set (1121 n) may form part
of a wire harness as provided in a vehicle.
The power controller (106) is configured to receive the input voltage from the battery or power supply device (102) and provide constant driving currents for illuminating each of the
plurality of the LED-based devices (104i n). The power controller (106) comprises a buck
converter (114) configured to receive the input voltage and generate the preconfigured driving voltage. The power controller (106) further comprises a plurality of driver circuits
(116i n) connected to the buck converter (114). The plurality of driver circuits (1161 n)
is connected so as to be parallel to each other. Each of the plurality of driver circuits
(116i n) receives the preconfigured driving voltage as produced by the buck converter
(114) and generates preconfigured constant current for driving the plurality of LED-based
devices (104i n).
It can be observed that because of the aforementioned construction, the power controller (106) comprises a single buck converter (114) as opposed to the plurality of buck converters and hence leads to several advantages including cost saving, size reduction, a decrease in complexity, a decrease in heat dissipation etc. It may be noted that despite the presence of a single buck converter (114), an independently controllable constant current can be provided
to each of the LED-based devices (104i n) as per its requirement. The current being
supplied to the LED-based devices (104i n) can be individually and independently
controlled by the current driver (1161 n).
The power controller (106) may additionally comprise a capacitor (118) to act as a backup in an event of non-availability of input voltage from the battery or power supply device (102). To ensure that the capacitor (118) does not charge the battery (102), a reverse protection device (120) is provided in the path between the battery (102) and the capacitor (118).
While the circuit of Figure 1 provides substantial benefits as stated above and provides satisfactory working, it has been observed that in one specific condition which is unique to automotive applications, the circuit provides less than the desired functioning.

Traditionally, a LED-based lighting system for non-vehicular application provides for two kinds of protections namely LED open circuit condition and LED short circuit condition.
However, in automotive applications, the second wire set (llOi n) that connects the power
controller (106) and each of the LED-based devices (104i n) may get shorted to
battery/power supply device (102). Such scenarios is illustrated in Figure 2 and referred to as "wire harness output short to battery condition". While in Figure 2, only one of the second wire set (llOi) is shown to be shorted, a person skilled in the art can understand that any of the remaining second wire set (1 IO2....11) can become shorted
It was observed that as long as the vehicles contained incandescent bulbs, these scenarios did not lead to any problems. However, when the plurality of incandescent bulbs were replaced with plurality of LED-based devices and the power controller comprising a buck converter
(114) and a plurality of current drivers (1161 n) connected in parallel is provided to drive
the plurality of LED-based devices, wire harness output short to battery condition lead to certain unexpected problem.
In particular, under wire harness output short to battery condition, all of the current drivers (116i....n) get overheated. If the device is operated for a prolonged period of time, one or more of the current drivers (116i....n) may fail. Although the reasons for the aforesaid are not clear, without wanting to be limited to any particular hypothesis, the Applicant believes that each of the current drivers defines an internal reverse body diode and under the wire harness output short to battery condition, the internal reverse body diode (which is inherent to every current driver) starts conducting input voltage and therefore, provides a path for electricity to flow from the output terminal to the input terminal of the current driver. Thus, the input voltage starts appearing at the junction terminal (JT). The buck converter is not affected by the appearance of input voltage at the junction point and merely stops functioning. However, since all of the remaining current drivers (1162....n) are connected to the junction terminal (TP), they start receiving the input voltage, which is substantially higher than the preconfigured driving voltage as normally generated by the buck converter (114). Thus, now each of the remaining current drivers (1162....n) is subjected to said higher input voltage, which leads to increased heat generation. While some current drivers may be in a position to handle the increased heat generation for a short period of time, some are not and in many instances, none is in a position to handle increased heat generation for a longer period of time and hence, fails.

Referring to Figure 3, there is illustrated a second circuit (200) for providing a constant current to a plurality of LED-based devices incorporated in a two-wheeled vehicle in accordance with an embodiment of the invention. The second circuit (200) is substantially similar to that of the first circuit (100) as shown in Figures 1 and 2, except for the plurality of
diodes (122i, 1222, 122n) that are provided between the junction terminal (JT) and the input
of each of the current driver (1161 n). The second circuit (200) having a plurality of diodes
(122i, 1222, 122n) disposed between the junction terminal and the input terminal of each
current driver (116i n) is able to address the unexpected problems being faced and which
was described in detail in Figure 2.
Referring to Figure 4, there is illustrated a third circuit (300) for providing a constant current to a plurality of LED-based devices incorporated in a two-wheeled vehicle in accordance with an embodiment of the invention. The third circuit (300) is substantially similar to that of the first circuit (100) as shown in Figures 1 and 2, except for the plurality of diodes (122i,
1222, 122n) that are provided at about the output terminal of each of the current driver
(116i n). The third circuit (300) having a plurality of diodes (122i, 1222, 122n) disposed
at about the output terminal of each of the current driver (1161 n) is able to address the
unexpected problems being faced and which was described in detail in Figure 2.
Thus, it can be said that plurality of diodes (122i, 1222, 122n) are introduced after the
junction terminal (JT) is able to address the unexpected problems, wherein the junction
terminal is located between the buck converter (114) and the plurality of current drivers
(116! n).
While certain present preferred embodiments of the invention have been illustrated and described herein, it is to be understood that the invention is not limited thereto. Clearly, the invention may be otherwise variously embodied, and practiced within the scope of the following claims.

WE CLAIM:

1.A LED-based illumination system for vehicular application, said illumination system
comprising:
a power controller (106) connected between a battery or power supply device (102)
and a plurality of LED-based devices (104i n), the power controller (106) being
configured to receive the input voltage from the battery or power supply device (102) and provide constant driving currents for illuminating each of the plurality of the
LED-based devices (104i n),
characterized in that the power controller (106) comprises:
a buck converter (114) configured to receive the input voltage and generate a
preconfigured driving voltage; and
a plurality of driver circuits (1161 n) connected in parallel to each other and to an
output of the buck converter (114), each of the plurality of driver circuits (1161 n)
being configured to receive the preconfigured driving voltage as produced by the buck
converter (114) and generate the preconfigured constant current for driving the
plurality of LED-based devices (104i n).
2. The LED-based illumination system for vehicular application as claimed in claim 1, wherein the power controller (106) comprises a capacitor (118) to act as a backup in an event of non-availability of input voltage from the battery or power supply device (102).
3. The LED-based illumination system for vehicular application as claimed in claim 2, wherein the power controller (106) further comprises a reverse protection device (120) provided in the path between the battery (102) and the capacitor (118).
4. The LED-based illumination system for vehicular application as claimed in claim 1, wherein the power controller (106) further comprises a plurality of diodes connected after a junction terminal (JT), the junction terminal being located between the buck converter (114) and the plurality of current drivers (116i n)-
5. The LED-based illumination system for vehicular application as claimed in claim 4, wherein the power controller (106) comprises a plurality of diodes (122i,

1222, 122n) connected between the junction terminal (JT) and the input of each of
the current driver (1161 n).
6. The LED-based illumination system for vehicular application as claimed in claim 4,
wherein the power controller (106) comprises a plurality of diodes (122i,
1222, 122n) connected at about the output terminal of each of the current driver
(1161 n).