Note: Descriptions are shown in the official language in which they were submitted.
CA 02740627 2011-05-19
L80006045CA
LIGHT EMITTING DIODE BULB
TECHNICAL FIELD
[00011 The invention relates generally to a Light Emitting Diode (LED) bulb,
specifically
although not exclusively to a LED bulb whose emitted light intensity can be
varied.
BACKGROUND
100021 The use of LED bulbs to replace incandescent bulbs in 12V applications
is gaining
popularity in a large number of applications such as head lights in
automobiles and other motor
vehicles, as well as for indoor lighting within the home, work place, boats
and recreational
vehicles. Incandescent bulbs, including most halogen bulbs, consume a large
amount of power,
generate a large amount of heat and have a relatively short life. They provide
only a warm
white illumination. Conversely, LED bulbs consume less power, generate less
heat and have a
longer operating life, although they tend to be more expensive than
incandescent bulbs.
[00031 For many applications, it is desirable to be able to vary the emitted
light intensity
of a LED bulb, for example between full brightness (bright) and a less bright
(dim) intensity.
One way of doing this is by decreasing the forward current using variable
resistors, voltage
regulators, or LED drivers, for example.
100041 However, LEDs have a minimum voltage threshold at which the LED
illuminates.
They also have a range of safe current operation, above which they will
overheat and burn.
These thresholds can vary between individual LEDs due to manufacturing
differences. These
differences are not usually visible at the recommended forward driving current
but at lower
currents some of the LEDs can stop illuminating entirely. Also, due to slight
colour differences
between LEDs and the LED emitted light intensity not being linear with
current, the colour
spectrum can shift at currents below full rating, which can result in some
LEDs appearing a
different colour. These unpredictable and non-uniform lighting effects are
undesirable and
1
CA 02740627 2011-05-19
L80006045CA
particularly inappropriate for some applications such as vehicle head lights
where a uniform
appearance is required for safety. Also, as the emitted light intensity is not
linear with current,
the dimming effects are unpredictable and uncontrollable.
[0005] For LED light bulbs that use a resistor, such as a shunt resistor, to
regulate the
operating current in LED strings, the relationship between the emitted light
intensity and
current is more linear than with LED bulbs including drivers and regulators.
However, these
bulbs are designed to operate at a fixed voltage, typically 12V. When the
operating voltage
varies or is not stable, which is often the case in automotive applications,
the emitted light
intensity varies accordingly. Also, these bulbs still have a minimum voltage
threshold below
which they cannot light up (which is under 8V for 3 LEDs connected in series)
and they burn-
out when the input voltage is higher than the one for which it is designed.
Therefore, these are
not suitable for use in automotive applications such as in Recreational
Vehicles where the
voltage typically ranges from 6V to 16V (with 12V as typical voltage).
[0006] Another approach to varying the emitted light intensity of LED bulbs is
pulse width
modulation (PWM) which involves turning the LEDs on and off at a high
frequency so that the
human eye cannot see the strobing effect. The longer the `on' period relative
to the `off period
of the LED, the brighter the LED will appear. However, the LED circuits are
complex and
require a timer or an oscillator to control the on/off, which adds to the
expense. Also, switching
speeds need to exceed the response time of the human eye. Therefore, the power
supply driving
the LED must also operate at high frequencies. Finally, this kind of device
tends to generate
audible noises.
[0007] Therefore, there is a need for an improved LED bulb which overcomes or
reduces
at least some of the above described problems.
SUMMARY
[0008] The embodiments of the present invention reduce the difficulties and
disadvantages
2
CA 02740627 2011-05-19
L80006045CA
of the aforesaid designs and treatments.
[0009] From a first aspect, the present invention resides in a LED bulb
comprising: a
support having at least one LED mounted on a first side, the at least one LED
being electrically
coupled to a circuit mounted on a second side of the support for driving the
LED bulb at a first
or a second light intensity level, the circuit comprising: input terminals
connectable to a power
supply for receiving an input voltage; a LED driver component for adjusting
(e.g. boosting or
reducing) the input voltage supplied to the at least one LED; a comparator
circuit for detecting
the input voltage and if above a threshold voltage closing a switch to drive
the LED bulb at the
first light intensity level.
[0010] When the input voltage is below the threshold voltage, but above a
minimum
required to light the at least one LED (minimum working voltage of the
circuit), the switch
may be completely or partially open and the LED bulb may thus be driven at the
second light
intensity level.
[0011] The present invention may present the advantage of, as the at least one
LED and
the circuit are mounted to either side of a support, providing the LED bulb as
a single piece
(one-piece) device. An exemplary additional advantage is that the support may
be a printed
circuit board. In this example, the LED bulb can be retrofitted into existing
light bulb sockets
without the need for adapters or additional hardware. The emitted light
intensity of the LED
bulb may thus be controlled by existing light control switches such as three-
position switches
or variable dimming switches.
[0012] The LED bulb of the present invention may be operated on at least two
emitted
light intensity levels, which can be a full emitted brightness or a less
intense emitted brightness
level. In other words, the first light intensity may be a bright intensity
level and the second
light intensity may be a dim intensity level. The LED bulb may achieve a
reproducible and a
consistent brightness at each level, making the LED bulb appropriate for a
large number of
applications. It may also be possible for the LED bulb of the present
invention to operate at
further light intensity levels, for example between the bright and the dim
intensity levels by use
3
CA 02740627 2011-05-19
L80006045CA
of an appropriate light control switch. For example, if a three position
switch is used, the LED
bulb may operate at a full brightness, a dim and an off mode. However, if a
variable dimmer
switch is used, the LED bulb may also operate at brightness levels between the
full brightness
and the dim level.
[0013] An optional preferred example connects the switch to a resistor, which
is
activated when the switch is closed. The switch may be a MOSFET.
[0014] In one exemplary application, such as in Recreational Vehicles, the
input voltage is
between 5V and 16V. The input voltage can be an AC or a DC supply.
[0015] The input terminals may be of any suitable size or shape to fit into
existing sockets.
In one exemplary embodiment, the input terminals are a pair of pins. Other
examples include a
wedge, screw or a bayonet type terminal or connector.
[0016] The present invention may present the exemplary advantage of the LED
bulb being
sized and shaped to fit into a socket suitable for receiving a G4-type bulb.
This means that the
exemplary dimmable LED bulb of the present invention may be retrofitted into
sockets for G4
bulbs without the need for adaptation or additional hardware.
[0017] The LED bulb may further comprise at least one diode for making the
light bulb
non-polarized or for converting an AC input voltage to a DC voltage, and at
least one capacitor
for filtering the input voltage.
[0018] An optional preferred example provides the at least one LED in an array
of LEDs.
In one exemplary embodiment, the array of LEDs comprises two parallel rows of
six LEDs, the
six LEDs being connected in a series. However, the LED array may comprise a
different
arrangement or a different number of LEDs.
[0019] In one exemplary embodiment, the comparator circuit includes a Zener
diode
4
CA 02740627 2011-05-19
L80006045CA
connected in series with a resistor and the switch. In this exemplary
embodiment, the threshold
voltage is a function of the voltage of the Zener diode and is the voltage
required to close the
switch. In this exemplary embodiment, the threshold voltage is about 9.5V to
close the switch
for the first light intensity level, using a Zener diode with a working
voltage of about 5.1 V. In
this exemplary embodiment, the second light intensity level, which is dim, is
operational
between the working minimum voltage of the circuit and about 9.5V.
[0020] In another exemplary embodiment, the comparator circuit includes a
comparator
integrated circuit, and at least one reference resistor to create a reference
voltage, wherein the
comparator integrated circuit compares the input voltage to the reference
voltage and closes the
switch when the input voltage is above the threshold voltage. In this
exemplary embodiment,
the switch is a MOSFET and the threshold voltage for the first light intensity
level is about
8.75V. The comparator integrated circuit may be powered by a Zener diode and a
resistor, by a
voltage regulator or directly on the input voltage.
[0021] The present invention may thus be directed to a LED bulb comprising a
support, a
LED driver component and a comparator circuit. The support has at least one
LED mounted on
a first side electrically coupled to a circuit mounted on a second side of the
support for driving
the LED bulb at a first or a second light intensity level. The circuit
comprises input terminals
connectable to a power supply for receiving an input voltage. The LED driver
component is for
adjusting the input voltage supplied to the at least one LED. The comparator
circuit is for
detecting the input voltage and, if above a threshold voltage, is for closing
a switch to drive the
LED bulb at the first light intensity level.
[0022] Optionally, the switch may be a MOSFET connected to a resistor, which
is
activated when the switch is closed. The first light intensity may be a bright
intensity level and
the second light intensity may be a dim intensity level. The input voltage may
be between 5V
and 16V. The input terminals may be a pair of pins. The support may be a
printed circuit board.
[0023] The LED bulb may also optionally comprise at least one diode for making
the light
bulb non-polarized. The LED bulb may further comprise at least one capacitor
for filtering the
CA 02740627 2011-05-19
L80006045CA
input voltage. The LED bulb may optionally be sized and shaped to fit into a
socket suitable
for receiving a G4-type bulb. The at least one LED may optionally be an array
of LEDs, e.g.,
two parallel rows of six LEDs, the six LEDs being connected in a series.
[0024] The comparator circuit includes a Zener diode connected in series with
a resistor
and the switch, in which case the switch may be a MOSFET. The threshold
voltage for the first
light intensity level may optionally be about 9.5V. The switch may optionally
remain open and
drive the LED bulb at the second light intensity level if the input voltage is
below a second
threshold voltage of about 8.5V. The MOSFET may further optionally function as
a variable
resistor and drive the LED bulb at a third light intensity level if the input
voltage is between the
second threshold voltage and the threshold voltage. The third light intensity
level may further
optionally vary linearly between the second light intensity level and the
first light intensity
level in relation to the input voltage compared to the threshold voltage and
the second
threshold voltage.
[0025] The comparator circuit may also optionally include a comparator
integrated circuit
and at least one reference resistor to create a reference voltage. The
comparator integrated
circuit may thus optionally compare the input voltage to the reference voltage
and close the
switch when the input voltage is above the threshold voltage. The threshold
voltage for the first
light intensity level may thus be about 8.75V.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Further aspects and advantages of the present invention will become
better
understood with reference to the description in association with the following
in which:
Figure 1 is a top plan view of a LED bulb according to an embodiment of the
invention;
Figure 2 is a bottom plan view of the LED bulb of Figure 1;
6
CA 02740627 2011-05-19
L80006045CA
Figure 3 is a block diagram of the LED bulb of Figure 1 according to an
embodiment of the invention; and
Figure 4 is a schematic circuit diagram of the LED bulb of Figure 1 according
to a
first embodiment of the invention; and
Figure 5 is a schematic circuit diagram of the LED bulb of Figure 1 according
to a
second embodiment of the invention.
DETAILED DESCRIPTION
[00271 This invention is not limited in its application to the details of
construction and the
arrangement of components set forth in the following description or
illustrated in the drawings.
The invention is capable of other embodiments and of being practiced or of
being carried out in
various ways. Also, the phraseology and terminology used herein is for the
purpose of
description and should not be regarded as limiting. The use of "including",
"comprising", or
"having", "containing", "involving" and variations thereof herein, is meant to
encompass the
items listed thereafter as well as, optionally, additional items. In the
following description, the
same numerical references refer to similar elements. Drawings are not
necessarily drawn to
scale.
[00281 The LED bulb of exemplary embodiments of the present invention may
provide
low heat generation and may offer low current consumption (low power). It is
therefore
environmentally friendly and may be considered to generate `green' energy. It
is expected that
the lifespan of the LED bulb range up to 40,000 hours when used in appropriate
circumstances
and is also expected to be easy to install. In come exemplary embodiments, the
LED bulb may
directly replace a 12V incandescent bulb without requiring any adaptors or any
hardware
modification. In other words, it may be retrofit into existing traditional
light bulb sockets
without requiring additional or different hardware. The LED bulb may also have
a 5V-16V
voltage operation range in some exemplary embodiments, making it appropriate
on 12V
7
CA 02740627 2011-05-19
L80006045CA
automotive voltage range. In some exemplary embodiments, the LED bulb is 90%
more
efficient than xenon bulbs, incandescent bulbs and Halogen bulbs traditional
lighting. Unlike
the PWM devices of the prior art, the LED bulb of exemplary embodiments do not
require
complex circuitry or expensive parts, and may have a silent operation (no
audible noise). In
some exemplary embodiments, the LED bulb is simple and cheap to construct and
of robust
design. The LED bulb of exemplary embodiments of the present invention can be
easily
adapted to replace a number of different types of traditional light bulbs,
such as G4, MR] 6, as
well as fluorescent tubes.
[00291 As used herein, the term "light emitting diode" (LED) is as understood
by persons
skilled in the art and denotes a semiconductor device that emit s visible
light when an
electric current passes through it.
100301 As used herein, the term "light emitting diode bulb" is a unit, module
or device
which includes at least one light emitting diode for emitting light and can be
connected to a
bulb socket by a connector. The connector can be of any type such as a bi-pin,
wedge, bayonet,
or wire, for example.
[00311 The present invention concerns light emitting diode (LED) bulbs, which
are
arranged to directly replace incandescent and halogen bulbs without the need
to modify
existing hardware such as the sockets for receiving the bulbs or the
on/off/dim switches for
controlling the bulbs. Specifically, the embodiments of the present invention
described herein
are related to LED bulbs whose emitted light intensity or brightness can be
varied between at
least two levels, typically a bright level and a dimmed level. The specific
embodiments
described herein are related to retrofittable LED bulbs for replacing G4 light
bulbs connectable
to three position switches (OFF / ON (bright) / DIM (dim)) for use in
Recreational Vehicles
(RVs) and other applications. However, it will be apparent to skilled persons
that the LED
bulbs of the present invention can also be fitted to multi position dimmer
switches (OFF /
Multiple DIM position / ON), e.g., a slider or rotating switch), or any other
type of variable
switch.
8
CA 02740627 2011-05-19
L80006045CA
[0032] A first exemplary embodiment of a LED bulb 10 of the present invention
is
illustrated in Figures 1 and 2. The LED bulb 10 comprises a backing plate 12
having a first side
14 including LEDs 16 arranged thereon as an array 17 (shown in Figures 3, 4
and 5), and a
second side 18 having electronic components 20 arranged thereon, which are
connected to the
LEDs 16 by an electronic circuit 22 (shown in Figures 3, 4 and 5). A connector
24 extends
from the backing plate 12 for connection to a power source (not shown) and is
connected to the
electronic circuit 22 for providing power to the LEDs to illuminate them.
100331 The backing plate 12 is a circular double-sided printed circuit board
(PCB) having
a diameter of about 30mm and a thickness of about 0.78mm, excluding the
thickness of the
LEDs 16 and the electronic components 20. The connector 24 comprises a pair of
straightened
pins, 10 mm in length, extending from an edge of the backing plate 12 and
preferably made of
a tin-plated metal, or the like. Therefore, the bulb 10 can be fitted into any
socket suitable for
receiving a G4 bulb. The connector 24 may extend from the first or second
sides 14, 18 of the
backing plate such as perpendicularly from the centre of one of the sides 14,
18 of the backing
plate 12. The connector 24 may also be a wedge, a bayonet, a wire, or any
other type of
connector instead of pins. The size and shape of the backing plate 12 and the
connector 24 of
the present embodiment is particularly suited to replace halogen and
incandescent G4 bulbs for
typical application as ceiling lights or under-cupboard lights. However, it
will be clear that the
present invention can also replace other types of bulbs by altering the size,
shape and type of
the backing board and the connector used.
[0034] The LED array 17 on the backing plate first side 14 comprises 12 LEDs.
Each LED
16 is preferably a 3.0 to 3.2V 5050 SMD with a beam angle of 120 deg and a
total power of
2.0-2.2W. The LEDs 16 may all be the same colour, or different colours, such
as warm white
(2800-3000K), cold white (6000-6500K), amber, blue, red, or green. Preferably,
the colour of
the LEDs does not change with luminous intensity in any of the embodiments of
the present
invention. It will be appreciated that any other type of LED can be used
instead of 5050 SMD
LEDs and more or less than 12 LEDs can also be used.
[0035] Figure 3 is a block diagram illustrating the electronic circuit 22 of
the present
9
CA 02740627 2011-05-19
L80006045CA
invention, which allows the LED bulb 10 to function with at least two light
intensities:
"Bright" or "Dim". In this exemplary embodiment, the electronic circuit 22 is
connectable to a
power source through a conventional G4 bulb socket which is connected to a
three position
switch: OFF (OV), ON (or bright) (12V), and DIM (6V). The electronic circuit
22 comprises
input terminals 25 for receiving an input voltage 26; a diode bridge and
filter(s) component 28
(which can be optional); a LED driver component 30; the LED array 17; and a
comparator
circuit 32 including a switch 34. The input voltage ranges from 5V to 16V (DC)
or 5V to 12V
(AC). The input voltage 26 goes through the diode bridge and filter component
28, which
allows the input voltage 26 to be applied in any polarity and converts an AC
input voltage to a
DC voltage, and outputs a filtered voltage VCC, which goes to the LED driver
component 30
and the comparator circuit 32. The LED driver component 30 adjusts the
filtered voltage VCC
(boosts or reduces) and provides a constant current to the LED array 17. The
LED array 17 can
be any number or arrangement of LEDs 16 connected in series or in parallel, in
this
embodiment 12 LEDs. The comparator circuit 32 reads the filtered voltage VCC
and identifies
if it is higher than a fixed (pre-set) voltage reference. If the filtered
voltage VCC is higher than
the voltage reference (also called threshold voltage), the comparator circuit
32 closes the
switch 34 to set the current of the LED driver component 30 to the "Bright"
intensity. In the
"Bright" intensity, both resistors R6 and R7 are enabled (connected in
parallel). If the filtered
voltage VCC is lower than the voltage reference the switch 34 is open and the
current of the
LED driver component 30 is set to the "Dim" intensity. In the "Dim" intensity,
only resistor R6
is enabled, and the LED bulb intensity is lower (about 20% of the bright
intensity) than the
"Bright" intensity. If the filtered voltage VCC is below the working voltage
of the LED driver
component 30, the circuit 22 will not function and the LED bulb intensity will
be OFF.
[00361 In a first exemplary embodiment of the electrical circuit 22 (shown in
Figure 4), the
LEDs 16 (DI to D12) are arranged as a 2 x 6 array, i.e., two parallel rows of
six LEDs 16
connected in a series. Other LED arrangements could be possible, such as 2 x 5
array, 3 x 5,
etc. The diode bridge and filter component 28 includes a diode bridge D16 for
full wave
rectification of an incoming AC voltage and for allowing connection without
polarity for an
incoming DC voltage. Two capacitors C2 and C4 are provided for filtering the
rectified
voltage. A varistor RV I is also included to protect the circuit against
overvoltage and voltage
CA 02740627 2011-05-19
L80006045CA
spikes.
[00371 The filtered input voltage VCC is connected to the LED driver component
30,
which comprises a LED driver U l. The LED driver U I is a boost converter that
runs at
600kHz fixed switching frequency. With the help of an inductor LI, a schottky
diode D15 and
a capacitor Cl, the LED driver U1, converts the filtered input voltage VCC to
a higher output
voltage, VLED. The higher output voltage VLED is about 18V to provide the
current needed to
each row of the LEDs 16 in the LED array 17. It will be appreciated that
depending on the
number and arrangement of LEDs in the LED array 17, a different LED driver can
be used to
either increase or to reduce the input voltage to provide the current needed
to power the LEDs.
[00381 The current that flows through the LED array 17 is fixed by the two
resistors, R6
and R7.Persons skilled in the art will appreciate that changing the value of
either or both of the
resistors R6 and R7 allows adjustment of one or both of the two light
intensities. In this
exemplary embodiment, the switch 34 in the comparator and switch circuit 32
includes a
MOSFET QI, or any other suitable switch. When the MOSFET QI is closed, the
current is at
maximum value (approximately 95mA) and the output light generated by the LEDs
(DI to
D12) is at the "Bright" intensity. When the MOSFET Ql is open, the current is
at minimum
value (approximately 20mA) and the light emitted by the LEDs (D1 to D12) is at
the Dim
intensity level.
[00391 In the exemplary embodiment of the electrical circuit 22 illustrated in
Figure 4, the
MOSFET Q I is controlled by a Zener diode D14 and a resistor R4. In this
exemplary
embodiment, the voltage of the Zener diode is 5.I V although it is possible to
use Zener diodes
with different working voltages. When the input voltage is equal to or over
about 9.5V, enough
current flows through D14 and R4 to create a voltage across R4 which then
polarizes the
MOSFET Q1. In this condition, the MOSFET Ql is closed and the resistor R7 is
activated in
the feedback loop of the LED Driver U I. Then the output current is at a
maximum value of
about 95mA ("Bright" intensity). When the input voltage is under about 8.5V,
not enough
current flows through D14 and R4 to polarize the MOSFET QI. In this condition,
the
MOSFET QI is open and the resistor R7 is not activated. Then the output
current is at the
11
CA 02740627 2011-05-19
L80006045CA
minimum value of about 20mA ("Dim" intensity). If the input voltage is between
about 8.5V to
about 9.5V (threshold voltage zone), the MOSFET QI is partly open. Between
about 8.5V to
about 9.5V, the MOSFET QI functions as a variable resistor and the LED current
is between
the maximum value of 95mA ("Bright" intensity) and the minimum value of 20mA
("Dim"
intensity). For example, if the input voltage is 9.OV, then the LED current
will be about 58mA
(20mA + (50% x (95mA - 20mA)). The threshold voltage zone is a linear region
between Dim
and Bright intensity. Said differently, in the threshold voltage zone, the LED
bulb emitted light
intensity will be at a third light intensity level between the "Dim" and the
"Bright" intensity
levels that is determined linearly relative to the input voltage compared to
the lower threshold
voltage (e.g., 8.5V) and the higher threshold voltage (e.g., 9.5V). When the
electronic circuit
22 is controlled by a three position switch, the threshold voltage zone is not
visible because the
voltage is a discrete value (OFF (OV), ON (or Bright) (12V), and Dim (6V).
With a variable
dimmer switch (e.g. a slider switch), the threshold voltage zone can be used
to set the LED
current between the Dim and Bright intensity, e.g., the emitted light
intensity will be at a third
level of intensity between "Bright" and "Dim" within the threshold voltage
zone. There will be
no emitted light from the LED array below about 2.7V at VCC (about 4V input
voltage) due to
the working voltage of the LED Driver U1. Alternative LED drivers could be
used to lower or
raise the working voltage of the circuit 22.
100401 It will be appreciated that the threshold voltage is a function of the
voltage of the
Zener diode used. Therefore, the value of the threshold voltage can be pre-set
or pre-
determined by using a different Zener diode with a different working voltage.
[00411 A second exemplary embodiment of the electrical circuit 22 is
illustrated in Figure
5, and differs from the exemplary embodiment of Figure 4 in that the MOSFET QI
is
controlled by a comparator IC (Integrated Circuit) U2. A resistor R5 and a
Zener diode D13
provide a stable and regulated 3.3V to power the comparator IC U2, but are
optional as the
comparator IC U2 can be powered directly on the VCC or by a voltage regulator.
Resistors RI
and R2 create a reference voltage (approximately 1.65V) to an inverting (-)
input of the
comparator IC U2. Resistors R3 and R4 do a voltage divider (0.22 x VCC) from
the filtered
input voltage VCC. The divided voltage is connected to a non-inverting (+)
input of the
12
CA 02740627 2011-05-19
L80006045CA
comparator IC U2. When the input voltage is over about 8.75V the voltage of
the non-inverting
(+) input of the comparator IC U2 is higher than the reference voltage (1.65V)
of the inverting
(-) input and the output of the comparator IC U2 is at high level (3.3V) and
then polarizes the
MOSFET Ql. In this condition, the MOSFET Q1 is closed and the resistor R7 is
activated in
the feedback loop of the LED Driver U l. Then the output current is at maximum
value of
95mA ("Bright" intensity). When the input voltage is below about 8.75V, the
voltage of the
non-inverting (+) input of the comparator IC U2 is under the reference voltage
(1.65V) of the
inverting (-) input and the output of the comparator IC U2 is at low level
(OV) and does not
polarize the MOSFET Q1. In this condition, the MOSFET QI is open and the
resistor R7 is not
activated. Then the output current is at minimum value of 20mA ("Dim" level).
In this
exemplary embodiment, there is no threshold voltage zone, but a fixed
threshold voltage of
about 8.75V. It will be appreciated that, in this exemplary embodiment, the
threshold voltage is
a function of the resistance of resistors RI and R2. Therefore, the value of
the threshold
voltage can be pre-set or pre-determined by using resistors with different
resistance values.
100421 The LED Driver IC is TPS61161. Alternatively, any another LED Driver IC
with
an analog input pin can be used to control the output current instead of
controlling the resistor
R7 in the feedback loop of the LED Driver. In other words, instead of
connecting the switch to
a resistor connected to the LED array, the switch and the resistor can be
connected to an analog
input pin of the LED driver to perform the LED intensity control. In this way,
the connection
of the MOSFET Q 1 could be used to control a voltage level to an analog input
pin of the LED
Driver to change the output current of the LED Driver.
100431 Although the exemplary embodiments of the invention have been described
in
relation to replacement incandescent and halogen G4 bulbs, it will be
appreciated that other
applications are within the scope of the present invention such as Cantalupi
(trademark) Lights,
Cabin (trademark)Lights and Imtra (trademark) Lights. It will also be
appreciated that the
embodiments of the LED bulb 10 described herein can be modified, without
departing from the
scope of the invention, for different uses and applications such as by
changing the shape and
size of the backing plate, or by changing the position or type of the
connector, or by changing
the type, number or arrangement of the LEDs, or by changing the electronic
components and
13
CA 02740627 2011-05-19
L80006045CA
IC.
[0044] It is important to note that the figures illustrate specific exemplary
embodiments of
the present invention, and are not intended to limit the scope of the present
disclosure or claims
to that which is presented therein. For example, a switching device such as a
MOSFET is
illustrated but other switching devices such as relay, bipolar transistors,
electronic analog
switch IC, etc. could be used. Also, a specific LED Driver U1 (TPS61161) is
illustrated but
any other LED Driver IC could be used. The LED bulb could comprise a single
LED rather
than an array. The emitted Iight intensities of the light bulb 10 need not be
bright and dim but
could be any light intensity. The diode bridge and filter component 28 may be
omitted from the
circuit 22, particularly for DC applications. The diode bridge and filter
component 28 may
comprise a diode only without the filter components or vice versa.
Alternatively, the diode
bridge and filter component 28 may be replaced by a filter for filtering the
input voltage 26.
[0045] While several embodiments of the invention have been described herein,
it will be
understood that the present invention is capable of further modifications, and
this application is
intended to cover any variations, uses, or adaptations of the invention,
following in general the
principles of the invention and including such departures from the present
disclosure as to
come within knowledge or customary practice in the art to which the invention
pertains, and as
may be applied to the essential features hereinbefore set forth and falling
within the scope of
the invention as defined in the appended claims.
14
