The present invention relates to a Light Emitting Diodes (LEDs) based illumination system
for vehicular applications such as two-wheeler, bike, motorbike, scooter and the like. In
particular, the invention relates to a control device for providing preconfigured constant
driving currents to a plurality of led based vehicular lights.
Background of the Invention:
The two-wheeled vehicle such as bike, motorbike, scooter and the like comprises a headlight
(which in turn comprises a low beam headlight and a high beam headlight), 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 the automobile industry is
evolving and moving towards replacing incandescent bulbs with the light-emitting diodes
(LED) based vehicular lights. The replacement of incandescent bulbs with LED-based
vehicular lights necessitates some additional components such as buck/boost converter,
current driver, and the like.
A conventional circuit (100) for illuminating the LED-based vehicular lights is illustrated in
Figure 1. The circuit (100) comprises a power source (102), which may be for example, a
battery or a combination of Alternating Current Generator and Regulator/Rectifier (ACG-RR)
as carried by the vehicle. The circuit (100) further comprises a plurality of LED-based
vehicular lights, only two of them are illustrated in Figure 1 for the purposes of ease (1041
and 1042). The LED-based vehicular lights (1041 and 1042) are connected to the power source
(102) via a power control device (106) which is configured to receive the input voltage from
the power supply (102) and provide constant driving currents for illuminating each of the
plurality of the LED-based vehicular lights (1041 and 1042). The circuit furthermore
comprises switches (1081 and 1082) for controlling the operation of the LED-based vehicular
lights. The power source (102), and the plurality of LED-based vehicular lights (1041 and
1042) are connected to the vehicle’s ground (110).
The power control device (106) comprises a headlight powering device (112) which provides
constant driving current to the headlight (which in turn comprises a low beam headlight and a
high beam headlight). The power control device (106) furthermore comprises a constant
current supplying device (114) which provides constant currents to the remaining lights in the
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vehicle. Since Figure 1 shows only two LED-based vehicular lights, the first LED-based
vehicular light (1041) is taken as the headlight and the second LED-based vehicular light
(1042) may be taken as a position light.
In one option, the headlight powering device (112) may comprise an H-bridge driving
inductor element. In one option, the constant current supplying device (114) may comprise a
buck converter (116) configured to receive the input voltage and generate a preconfigured
driving voltage; and a plurality of linear driver elements (1181........n) connected in parallel to
each other and to an output of the buck converter (116). For the purposes of simplicity, in
Figure 1, only one linear driver element (118) is shown.
The power control device (106) comprises a controller (120) that is connected to the switches
(1081 and 1082) for sensing their operation and based on their operation, control operation of
the headlight powering device (112) and the constant current supplying device (114). To
enable the controller (120) sense operation of the switches (1081 and 1082), each switch is
connected to the controller (120) via a switch sensing resistance (1221, 1222) and a voltage
divider element (1241, 1242).
The components of the power control device (106) are connected to a power control device
ground terminal (126). In particular, the headlight powering device (112), the buck converter
(116) forming part of the constant current supplying device (114), the linear driver element
(118) forming part of the constant current supplying device (114), the controller (120), the
switch sensing resistances (1221, 1222), and the voltage divider elements (1241, 1242) are
connected to the power control device ground terminal (126). The power control device
ground terminal (126) is then connected to the vehicle’s ground (110) via a power control
device ground wire (128).
It has been observed that as long as the power control device ground terminal (126) is
connected to the vehicle’s ground (110), the power control device (106) performs as per the
requirement. On the other hand, if due to any reason, the electrical path between the power
control device ground terminal (126) and the vehicle’s ground (110) is interrupted, as shown
by arrow (130) in Figure 2, problems are faced.
Without wanting to be limited to specific instances, one instance when the electrical path
between the power control device ground terminal (126) and the vehicle’s ground (110) is
4
interrupted includes the power control device ground wire (128) getting disconnected from
the power control device ground terminal (126). Another instance when the electrical path
between the power control device ground terminal (126) and the vehicle’s ground (110) is
interrupted includes the power control device ground wire (128) getting disconnected from
vehicle ground (110). There may be other ways by which the electrical path between the
power control device ground terminal (126) and the vehicle’s ground (110) may get
interrupted.
In particular, when the electrical path between the power control device ground terminal
(126) and the vehicle’s ground (110) is interrupted; and the headlight powering device (112)
is in any one of pass state or the high beam state, the constant current supplying device (114)
generates excess heat and over a period of time, may get damaged.
Thus, there exists a need to provide a solution to address the aforesaid problem faced when
the electrical path between the power control device ground terminal (126) and the vehicle’s
ground (110) is interrupted.
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 control device (210) for providing
preconfigured constant driving currents to a plurality of LED-based vehicular lights (2041
.....n). The control device (210) comprises a headlight powering device (212) providing
constant driving current to an LED-based headlight in the vehicle and a constant current
supplying device (214) providing a constant current to at least one further LED-based light in
the vehicle. The control device (210) further comprises a governing unit (216) adapted to
keep the headlight powering device (212) in a non-operating state if the voltage at an input of
the headlight powering device (212) is outside a predetermined range.
In an embodiment of the invention, the control device (210) comprises a control device
ground terminal (228) connectable to the vehicle’s ground terminal.
5
In another embodiment of the invention, the control device (210) and the plurality of LEDbased vehicular lights (2041...n) form part of a circuit (200), the circuit (200) further
comprising a power source (202) and plurality of switches (2061...n) for controlling operation
of the LED-based vehicular lights (2041...n).
In yet another embodiment of the invention, the constant current supplying device (214)
comprises a buck converter (218) configured to receive the input voltage and generate a
preconfigured driving voltage; and a plurality of linear driver elements (2201...n) connected in
parallel to each other and to output of the buck converter (218).
In still another embodiment of the invention, the control device (210) comprises a controller
(222) connected to the switches (2061 and 2062) for sensing their operation and based on their
operation, control operation of the headlight powering device (212) and the constant current
supplying device (214).
In a further embodiment of the invention, the controller (222) is connected to the switches
(2061 and 2062), via a corresponding switch sensing resistance (2241, 2242) and voltage
divider element (2261, 2262).
In a furthermore embodiment of the invention, the governing unit (216) exercises direct
control over the headlight powering device (212).
In another embodiment of the invention, the governing unit (216) is coupled to the controller
(222) and exercises indirect control over the headlamp powering device (212).
In an embodiment of the invention, when the governing unit (216) exercises direct control
over the headlight powering device (212), the governing unit (216) comprises: a transistorbased switch (236) connected between the input line and the headlight powering device
(212); and a voltage divider unit connected between the input line & the headlight powering
device (214), the voltage divider unit controlling the operation of the transistor-based switch
(236).
In another embodiment of the invention, when the governing unit (216) exercises indirect
control over the headlight powering device (212), the governing unit (216) comprises a
voltage divider unit and an analog to digital converter (238) connected between the input line
6
& the headlight powering device, the analog to digital converter (238) being connected to the
controller (222).
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 circuit (100) for providing a constant current to a plurality of LEDbased devices incorporated in a two-wheeled vehicle in accordance with the teachings of the
prior art;
Figure 2 demonstrates the circuit (100) of the prior art with the electrical path between the
power control device ground terminal (126) and the vehicle’s ground being interrupted;
Figure 3 demonstrates a circuit (200) for providing supply to a plurality of LED-based
vehicular lights, wherein the circuit comprises a control device (210) constructed in
accordance with a first embodiment of the present invention;
Figure 4 demonstrates a circuit (200) for providing supply to a plurality of LED-based
vehicular lights, wherein the circuit comprises a control device (210) constructed in
accordance with a second embodiment of the present invention;
Figure 5 demonstrates the circuit (200) for providing supply to a plurality of LED-based
vehicular lights, showing the construction of the governing unit (216) and the controlling of
the headlight powering device (212) in accordance with the first embodiment of the present
invention; and
Figure 6 demonstrates the circuit (200) for providing supply to a plurality of LED-based
vehicular lights, showing the construction of the governing unit (216) and the controlling of
the headlight powering device (212) in accordance with the second embodiment of the
present invention.
7
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
8
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.
Now referring to Figure 3, there is illustrated a circuit (200) for illuminating the LED-based
vehicular lights. The circuit (200) comprises a power source (202), which may be for
example, a battery or a combination of Alternating Current Generator and Regulator/Rectifier
(ACG-RR) as carried by the vehicle. The circuit (200) further comprises a plurality of LEDbased vehicular lights, only two of them are illustrated in Figure 3 for the purposes of ease
(2041 and 2042). The circuit furthermore comprises switches (2061 and 2062) for controlling
the operation of the LED-based vehicular lights. The power source (202), and the plurality of
LED-based vehicular lights (2041 and 2042) are connected to the vehicle’s ground via vehicle
ground wire (208).
The LED-based vehicular lights (2041 and 2042) are connected to the power source (202) via
a control device (210) which is configured to receive the input voltage from the power supply
(202) and provide constant driving currents for illuminating each of the plurality of the LEDbased vehicular lights (2041 and 2042).
The control device (210) comprises a headlight powering device (212) which provides
constant driving current to the headlight. The control device (210) furthermore comprises a
constant current supplying device (214) which provides constant currents to the remaining
LED-based vehicular lights. Since Figure 3 shows only two LED-based vehicular lights, the
first LED-based vehicular lights (2041) are taken as the headlight and the second LED-based
vehicular lights (2042) may be taken as a position light. The control device (210) further
comprises a governing unit (216) which is adapted to keep the headlight powering device
9
(212) in a non-operating state if the voltage at an input of the headlight powering device
(212) is outside of a predetermined range.
In one option, the constant current supplying device (214) may comprise a buck converter
(218) configured to receive the input voltage and generate a preconfigured driving voltage;
and a plurality of linear driver elements (2201........n) connected in parallel to each other and to
an output of the buck converter (218). For the purposes of simplicity, in Figure 3, only one
linear driver element (220) is shown.
The control device (210) comprises a controller (222) that is connected to the switches (2061
and 2062) for sensing their operation and based on their operation, control operation of the
headlight powering device (212) and the constant current supplying device (214). To enable
the controller (222) sense operation of the switches (2061 and 2062), each switch is connected
to the controller (222) via a switch sensing resistance (2241, 2242) and a voltage divider
element (2261, 2262).
The components of the control device (210) are connected to a control device ground
terminal (228). In particular, the headlight powering device (212), the buck converter (218)
forming part of the constant current supplying device (214), the linear driver element (220)
forming part of the constant current supplying device (214), the controller (222), and the
switch sensing resistances (2241, 2242) are connected to the control device ground terminal
(228). The control device ground terminal (228) is then connected to the vehicle’s ground via
a control device ground wire (230). In one option, the headlight powering device (212) may
comprise an H-bridge driving inductor element.
In the circuit (200) as shown in Figure 3, as long as the control device ground terminal (228)
is connected to the vehicle’s ground, the voltage at an input of the headlight powering device
(212) is within a predetermined range. On the other hand, if the electrical path between the
control device ground terminal (228) and the vehicle’s ground is interrupted, the voltage at
the input of the headlight powering device (212) falls outside the predetermined range.
By way of a non-limiting example, the predetermined range may be governed by the voltage
being supplied by the power source (202) (which may not be constant, for battery). By way of
another non-limiting example, the predetermined range may be governed by the minimum
voltage at which the control device (210) has to come to an operating state. By way of
10
another non-limiting example, the predetermined range may be governed by a voltage drop
across an LED-based vehicular light that is connected to the constant current supplying
device (214). By way of a non-limiting example, the predetermined range may be governed
by the voltage being supplied by the power source (202) and a voltage drop across an LEDbased vehicular light which is having the minimum voltage requirement. By way of a nonlimiting example, the predetermined range may be governed by the voltage being supplied by
the power source (202); a voltage drop across an LED-based vehicular light which is having
the minimum voltage requirement and a minimum voltage at which the control device (210)
has to come to an operating state. Thus, based on one or more of these factors, the
predetermined range may be set.
Thus, by detecting that the input of the headlight powering device (212) is outside the
predetermined range, an interruption between the electrical path between the control device
ground terminal (228) and the vehicle’s ground can be detected. If in response to such
detection, the headlight powering device (212) is maintained in a non-operating state, the
constant current supplying device (214) neither generates excess heat and nor gets damaged.
Thus, the problem faced in the problem is fully and satisfactorily solved.
The governing unit (216) as proposed by the present invention detects the input of the
headlight powering device (212) and detects whether the input of the headlight powering
device (212) is outside the predetermined range. In case the input of the headlight powering
device (212) is outside the predetermined range, the governing unit (216) keeps the headlight
powering device (212) in a non-operating state.
In an embodiment of the invention, the governing unit (216) may exercise direct control over
the headlight powering device (212) and keeps the headlight powering device (212) in
operating state or in non-operating state. This aspect is demonstrated in Figure 3 and is
characterized by a direct connection between the governing unit (216) and the headlight
powering device (212).
In an alternative embodiment of the invention, the governing unit (216) may exercise indirect
control over the headlight powering device (212) and keeps the headlight powering device
(212) in operating state or in non-operating state. As indicated above, the control device (210)
comprises a controller (222) that controls the operation of the headlight powering device
(212). Thus, by way of a non-limiting example, the governing unit (216) may exercise control
11
over the headlight powering device (212) via the controller (222) and keeps the headlight
powering device (212) in operating state or in non-operating state. This aspect is
demonstrated in Figure 4, wherein the governing unit (216) can be seen to be coupled to the
controller (222) and the controller (222) is coupled to the headlight powering device (212).
As there is no other difference between the circuit (200) or the control device (210) shown in
Figure 3 and the circuit (200) or the control device (210) shown in Figure 4, the remaining
part is not being described.
Now referring to Figure 5, the construction of the governing unit (216) in the circuit (200) of
Figure 2 is illustrated. It can be seen that the governing unit (216) in one embodiment
comprises a voltage divider comprising a first resistor (232) and a second resistor (234)
which are connected in series and to the input line which supplies voltage to the headlight
powering device (212). The governing unit (216) further comprises a transistor-based switch
(236) which is connected between the input line and the headlight powering device (212). An
output from the voltage divider is taken and fed to the base of the transistor-based switch
(236) thereby switching ON and OFF the transistor-based switch (236). In case the transistorbased switch (236) is in ON state, the headlight powering device (212) is in an operating
state. On the other hand, if the transistor-based switch (236) is in the OFF state, the headlight
powering device (212) is in a non-operating state.
Now referring to Figure 6, the construction of the governing unit (216) in the circuit (200) of
Figure 3 is illustrated. It can be seen that the governing unit (216) in one embodiment
comprises a voltage divider comprising a first resistor (232) and a second resistor (234)
which are connected in series and to the input line which supplies voltage to the headlight
powering device (212). The governing unit (216) further comprises an analog to digital
converter (238) which receives an output from the voltage divider. The analog to digital
converter (238) converts the output as received from the voltage divider into a digital signal
and then feeds the same to the controller (222). The controller (222) based on the digital
signal received from the analog to digital converter keeps the headlight powering device
(212) in the operating state or in a non-operating state.
It can be seen that not only does the solution proposed herein addresses the problem faced in
the prior art, the solution is also very cost-effective. For example, if we compare the control
device (210) as shown in Figure 5 with the power control device (106) as shown in Figure 1
(or Figure 2), it can be noticed that it merely contains 3 additional components which are the
12
two resistors (232, and 234) and one transistor (236). Thus, the solution as proposed herein
does not impose substantial costs.
If we compare the device (210) as shown in Figure 6 with the power control device (106) as
shown in Figure 1 (or Figure 2), it can be noticed that it merely contains 2 additional
components which are the two resistors (232, and 234). Thus, even this solution does not
impose substantial costs.
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 control device (210) for providing preconfigured constant driving currents to a
plurality of LED-based vehicular lights (2041....n), said control device comprising:
a headlight powering device (212) providing constant driving current to a
LED-based headlight;
a constant current supplying device (214) providing a constant current to at
least one further LED-based light in the vehicle; and
a governing unit (216) adapted to keep the headlight powering device (212) in
a non-operating state if the voltage at an input of the headlight powering
device (212) is outside a predetermined range.
2. The control device as claimed in claim 1, wherein the control device (210) comprises
a control device ground terminal (228) connectable to vehicles ground terminal.
3. The control device as claimed in claim 1, wherein the control device (210) and the
plurality of LED-based vehicular lights (2041...n) form part of a circuit (200), the
circuit (200) further comprising a power source and plurality of switches (2061...n) for
controlling operation of the LED-based vehicular lights (2041...n).
4. The control device as claimed in claim 1, wherein the constant current supplying
device (214) comprises a buck converter (218) configured to receive the input voltage
and generate a preconfigured driving voltage; and a plurality of linear driver elements
(2201...n) connected in parallel to each other and to output of the buck converter (218).
5. The control device as claimed in claim 1, wherein the control device (210) comprises
a controller (222) connected to the switches (2061 and 2062) for sensing their
operation and based on their operation, control operation of the headlight powering
device (212) and the constant current supplying device (214).
6. The control device as claimed in claim 1, wherein the controller (222) is connected to
the switches (2061 and 2062), via a corresponding switch sensing resistance (2241,
2242) and voltage divider element (2261, 2262).
7. The control device as claimed in claim 1, wherein the governing unit (216) exercises
direct control over the headlight powering device (212).
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8. The control device as claimed in claim 1, wherein the governing unit (216) is coupled
to the controller (222) and exercises indirect control over the headlight powering
device (212).
9. The control device as claimed in claim 7, wherein the governing unit (216) comprises:
a transistor-based switch (236) connected between the input line and the headlight
powering device (212); and
a voltage divider unit connected between the input line & the headlight powering
device (214), the voltage divider unit controlling the operation of the transistor-based
switch (236).
10. The control device as claimed in claim 8, wherein the governing unit (216) comprises
a voltage divider unit and an analog to digital converter (238) connected between the
input line & the headlight powering device, the analog to digital converter (238) being
connected to the controller (222).