U.S. patent application number 14/715171 was filed with the patent office on 2016-01-21 for retrofit led lighting system.
The applicant listed for this patent is Lunera Lighting, Inc.. Invention is credited to Donald Barnetson, Daryl A. Cheim, Ardeshir Esmaeili, John X. Zhang.
Application Number | 20160018061 14/715171 |
Document ID | / |
Family ID | 52466700 |
Filed Date | 2016-01-21 |
United States Patent
Application |
20160018061 |
Kind Code |
A1 |
Barnetson; Donald ; et
al. |
January 21, 2016 |
Retrofit LED Lighting System
Abstract
A retrofit LED lighting system for replacement of existing metal
halide lamp driven by magnetic ballast is provided. The retrofit
lamp includes a circuit that converts the AC current supplied by
magnetic ballast to DC current required for illuminating the
LEDs.
Inventors: |
Barnetson; Donald; (San
Jose, CA) ; Zhang; John X.; (Walnut Creek, CA)
; Cheim; Daryl A.; (San Jose, CA) ; Esmaeili;
Ardeshir; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lunera Lighting, Inc. |
Santa Clara |
CA |
US |
|
|
Family ID: |
52466700 |
Appl. No.: |
14/715171 |
Filed: |
May 18, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13969613 |
Aug 19, 2013 |
9033545 |
|
|
14715171 |
|
|
|
|
Current U.S.
Class: |
362/294 |
Current CPC
Class: |
F21K 9/23 20160801; F21K
9/238 20160801; F21V 3/04 20130101; F21V 23/006 20130101; F21V
29/85 20150115; H05K 1/056 20130101; F21V 29/70 20150115; F21V
29/773 20150115; F21K 9/232 20160801; F21V 23/026 20130101 |
International
Class: |
F21K 99/00 20060101
F21K099/00; F21V 3/04 20060101 F21V003/04; F21V 29/70 20060101
F21V029/70; F21V 23/02 20060101 F21V023/02; H05K 1/05 20060101
H05K001/05 |
Claims
1. A retrofit LED lamp for replacing a socket type metal halide
lamp driven by a magnetic ballast, the said lamp comprising: a
string of LED mounted on a MCPCB plate; a housing that serves as a
mean for dissipating the heat generated by LED; a diffuser placed
over the MCPCB plate to diffuse the light emitted by LED; a PCB
circuit to provide the voltage input to the string of LED, the said
PCB circuit convert the output from the magnetic ballast to DC
current required to illuminate the string of LED; a base connector
adapted to fit into the socket meant for metal halide lamp, the
said base connector provides electrical connection between the
output of magnetic ballast and the said PCB circuit.
2. The retrofit LED lamp of claim 1 wherein the MCPCB plate is
fabricated from material consisting of aluminum alloy or dielectric
polymer.
3. The retrofit LED lamp of claim 1 wherein the string of LED is
mounted on the horizontal axis of MCPCB plate.
4. The retrofit LED lamp of claim 1 wherein the diffuser is made
from composite material of polymer and glass fiber, or from a
polycarbonate/acrylic material.
5. The retrofit LED lamp of claim 1 wherein the diffuser diffuses
the light emitted by the string of LEDs.
6. The retrofit LED lamp of claim 1 wherein the housing is
fabricated from the material consisting of aluminum, copper,
thermoplastic material, or natural graphite.
7. The retrofit LED lamp of claim 1 wherein the input to the PCB
circuit comprised of a bridge rectifier that converts AC waveform
into DC waveform.
8. The retrofit LED lamp of claim 1 wherein the PCB circuit has an
inductor coil to reduce current crest factor.
9. The retrofit LED lamp of claim 1 wherein a capacitor is used in
the PCB circuit to enhance the power factor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit to U.S. patent application
Ser. No. 13/969,613, filed Aug. 19, 2013, the disclosure of which
is hereby incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a lighting system, and more
particularly to a LED retrofit lighting system for metal halide
lamps.
BACKGROUND
[0003] A metal-halide lamp generates light by passing an electric
arc through a gaseous mixture of vaporized mercury and metal
halides. The metal halide lamps have high luminous efficiency and
produce an intense white light. The metal halide lamps are used in
wide area overhead lighting of commercial, industrial, and public
spaces, such as parking lots, sports arenas, factories, and retail
stores, as well as residential security lighting and automotive
headlamps. Approximately 13% of US commercial space uses metal
halide lamp for illumination purpose.
[0004] The metal halide lamp though used widely suffers from
several disadvantages. A cold metal-halide lamp cannot immediately
begin producing its full light capacity and requires approximately
5 minutes coming to full brightness. Furthermore if the power is
interrupted, even briefly, the lamp's arc will extinguish, and the
high pressure that exists in the hot arc tube will prevent
re-striking the arc and therefore metal halide lamps must be
allowed to cool for up to 20 minutes before they can be
restarted.
[0005] Apart from having moderate life span of approximately 10000
hours and poor lumen maintenance, the metal halide lamps are
hazardous and risky to use. The metal halide lamps contain a
significant amount of Mercury and are prone to risk of explosion.
Over a period of use, arc tube gets weak and since the gases are
present at a significantly high pressure, chances for explosion of
the Metal halide lamps are always there.
[0006] The most recent evolution in lighting is solid state
lighting based on light emitting diode (LED) technology. The light
generation principle is similar to what happens in gas discharge
lamps, but now the discharge happens in a solid state material:
orbit changing electrons cause atoms to get `excited` that
subsequently fall back to their natural state thereby releasing its
surplus energy in the form of radiation. The advancement in
microelectronics technology has led light-emitting-diode (LED)
technology to generate lighting and special purpose lighting
applications. The LEDs have a large lifespan of 50,000 hrs and are
RoHS compliant, i.e. they do not contain mercury or other toxic
substances.
[0007] In view of the aforementioned disadvantages associated with
the use of metal halide lamps and the technological advancement in
LED technology, there is concern rising for replacing metal halide
lamps with LED lamps. However the main concern for replacing metal
halide lamp with LED lamp is the considerable labor costs involved
in the installation, because it will require the opening of the
light fixture to disassemble the existing ballast, either it be an
electronic one, or a magnetic one. Another concern involved in the
replacement of metal halide lamp with LED is the lack of recycle
scheme of ballast. Therefore, in view of above constraints, it
would be advantageous to have LED retrofit lamp that can directly
replace the existing metal halide lamps.
BRIEF SUMMARY OF THE INVENTION
[0008] The present invention provides a retrofit LED lamp that
provides a replacement for a Metal Halide lamp driven by a magnetic
ballast. The LED lamp is designed to replace the existing metal
halide lamp and consists of a circuit that converts the AC waveform
generated by the magnetic ballast into the DC waveform suitable for
the LEDs.
[0009] In aspects of the present invention, the retrofit LED lamp
includes a MCPCB plate mounted with strings of LEDs, a heat sink to
dissipate the heat generated by LEDs, a diffuser, a PCB circuit
that converts the output from the magnetic ballast into the DC volt
required for illuminating LEDs, and a base adaptable to fit into a
socket. The PCB circuit includes a bridge rectifier. The retrofit
lamp is compatible with existing magnetic ballast and hence does
not require the removal of magnetic ballast while replacing the
metal halide lamp with the LED lamp.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The preferred embodiment of the invention will hereinafter
be described in conjunction with the appended drawings provided to
illustrate and not to limit the scope of the invention, wherein
like designation denote like element and in which:
[0011] FIG. 1 illustrates a retrofit LED lamp for replacement of a
metal halide lamp driven by a magnetic ballast, in accordance with
an embodiment of the present invention.
[0012] FIG. 2A illustrates a schematic representation of an array
of LEDs arranged on a MCPCB plate in accordance with an embodiment
of the present invention.
[0013] FIG. 2B is a schematic representation LEDs connected in a
series to the output of a PCB circuit.
[0014] FIG. 3 shows the schematic illustration of the PCB used in
LED retrofit lamp, in accordance with an embodiment of the present
invention.
[0015] FIG. 4 illustrates a circuit diagram of a retrofit LED lamp
driven by a magnetic ballast, in accordance with an embodiment of
the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0016] In the following detailed description of embodiments of the
invention, numerous specific details are set forth in order to
provide a thorough understanding of the embodiment of invention.
However, it will be obvious to a person skilled in art that the
embodiments of invention may be practiced with or without these
specific details. In other instances well known methods, procedures
and components have not been described in detail so as to not
unnecessarily obscure aspects of the embodiments of the
invention.
[0017] Furthermore, it will be clear that the invention is not
limited to these embodiments only. Numerous modifications, changes,
variations, substitutions and equivalents will be apparent to those
skilled in the art, without parting from the spirit and scope of
the invention.
[0018] The present invention provides a retrofit LED lamp that
provides a replacement for a metal halide lamp driven by a magnetic
ballast. The circuit of the retrofit LED lamp includes a bridge
rectifier that converts the AC waveform of the magnetic ballast to
a single sided waveform to generate DC output to the LED. The
frequency of waveform generated by the magnetic ballast is low;
Therefore, a traditional rectifier is sufficient to provide the
desired DC output required for illumination of LED.
[0019] The retrofit lamp is a LED lamp that provides a replacement
to the existing metal halide lamp driven by the magnetic ballast.
The retrofit lamps work on the electric current supplied by the
magnetic ballast, and hence it can directly replace the existing
metal halide lamp without removing the existing ballast.
[0020] FIG. 1 illustrates a retrofit LED lamp for replacement of a
metal halide lamp driven by a magnetic ballast, in accordance with
an embodiment of the present invention. Referring to FIG. 1, the
retrofit lamp includes a plurality of LEDs mounted on a MCPCB plate
104 and is placed in a housing 106 that keeps the plurality of LEDs
in a fixed position. The housing 106 can be circular,
semi-circular, cylindrical, rectangular, parabolical or a square
housing typically used with lamp. The housing 106 provides a means
for heat sink for LEDs by providing a path for heat from the LED
source to the outside medium. The thermal conductivity of the
material of the housing 106 directly affects dissipation of heat
through conduction. The housing 106 can be made of aluminum or
copper or thermoplastic material or a natural graphite solution
that offer better thermal transfer than copper with a lower weight
than aluminum. The heat sink made of natural graphite solution has
the ability to be formed into complex two dimensional shapes. The
housing 106 is covered with a diffuser 102 to emit the light
generated by the plurality of LEDs to outside. At the end of
housing 106, a ring plate 108 is attached that contains the circuit
for converting the AC input from magnetic ballast to DC waveform. A
base connector 110 is provided at the bottom of ring plate 108 for
fitting the retrofit lamp into the socket.
[0021] In an embodiment of the present invention the pluralities of
LEDs are arranged on the MCPCB Metal Core PCB) plate 104. The MCPCB
104 incorporates a base metal material as heat spreader as an
integral part of the circuit board. The base metal material can be
aluminum alloy or alternatively it incorporates a dielectric
polymer layer with high thermal conductivity for lower thermal
resistance. The plurality of LEDs is arranged in a linear manner on
the MCPCB plate 104 such that the output angle of the emitted light
is perpendicular to the surface of MCPCB plate 104. The MCPCB plate
104 is mounted on the housing 106 through a screw. The housing 106
is meant for dissipation of excess heat generated by the lighting
of LEDs. The housing 106 acts as a heat sink for the retrofit lamp
assembly. The housing 106 is preferably fabricated from aluminum,
though it can be fabricated from a material having high thermal
conductivity that includes, but are not limited to copper, natural
graphite or a thermoplastic material. The housing 106 is designed
to have a large surface area for maximum heat dissipation.
Alternatively the housing is provided with a number of fine fins.
The diffuser 102 is mounted on the housing 106 through a screw for
diffusing the light emitted by LED. The diffuser 102 is made of a
glass material fabricated in a shape such that the light emitted by
the LED is released by the diffuser 102 effectively.
[0022] In an embodiment of the present invention, the retrofit lamp
may have a curved diffuser 102. Based on the surface area of the
shining surface of the panel, the size and thickness of the optimum
light diffuser may be determined. The suitable diffuser 102 may be
made from a composite material of polymer and glass fiber, or from
a polycarbonate/acrylic material. These materials may be designed
with varying amounts of hardness and light refractory
characteristics. A sufficient hardness and thickness are required
for the structural integrity of the overall panel and refractory
characteristics, which are also related to the thickness, are
selected in order to cause the light to be transmitted evenly
across the diffuser 102. Another advantage of using a sufficiently
thick diffuser is that it prevents the LED sources from getting
visible. Thus, increasing the aesthetic values and preventing from
causing multiple shadows on the object.
[0023] The ring plate 108 is provided at the end of housing 106
such that the ring plate 108 seals the bottom circular end of the
housing 106. A PCB is mounted on the ring plate 108, where the said
PCB includes a circuit for converting the AC waveform received from
the ballast to a DC volt suitable for driving the LEDs. The PCB
circuit gets input power from the base connector 110. The base
connector 110 fits into the socket meant for metal halide lamp and
receives the AC input waveform form the magnetic ballast.
[0024] FIGS. 2A and 2B illustrate a schematic representation of an
array of LEDs arranged on a MCPCB plate in accordance with an
embodiment of the present invention. Referring to FIG. 2A, the
MCPCB plate 104 is mounted with a plurality of LEDs 202 arranged in
a linear fashion. The plurality of LEDs 202 is arranged on the
MCPCB plate in such a manner that the output angle of the light is
in perpendicular orientation to the MCPCB plate. Since the diffuser
102 is fitted over the MCPCB plate 104 with horizontal axis
parallel to the MCPCB plate 104, hence the light emitted by the
plurality of LEDs 202 will pass through the exit aperture directly.
This makes the retrofit lamp a directional emitter and over 80
percent of the light is emitted directly from the fixture and only
a small amount of the light is emitted towards the surface. The
light emitted towards surface will then be reflected from the
surface coated with reflector. The characteristic feature of the
retrofit lamp, the lamp emitting light directly from the exit
aperture makes the optical efficiency of the retrofit lamp greater
than 80 percent. The conventional downlight lamps are only 50
percent optical efficient as the downlight metal halide lamp is
omni-directional emitter and only a small portion of light is
emitted directly from the exit aperture and a large portion of
light is emitted after reflection from the lamp surface. FIG. 2B
shows a plurality of LEDS 202 connected in a series to the output
of PCB circuit.
[0025] FIG. 3 shows the schematic illustration of the PCB used in
LED retrofit lamp, in accordance with an embodiment of the present
invention. Referring FIG. 3, the output 302 from the magnetic
ballast serves as an input to the PCB circuit. The input is then
fed into a bridge rectifier 306 that converts the AC waveform of
the magnetic ballast to a single sided waveform. The bridge
rectifier 306 is made of four diodes 304 arranged in a bridge
manner. A capacitor 310 may be placed at the input to the bridge
rectifier 306. The capacitor 310 reduces the compensation
capacitance and helps in bringing the power factor close to 1.
[0026] In an embodiment of the present invention the capacitor 310
may be damped with a series resistor to reduce harmonic
distortion.
[0027] In another embodiment of the present invention, an inductor
can be placed after the bridge rectifier 306 to reduce the current
crest factor of the waveform presented to the LED 202.
[0028] FIG. 4 illustrates a circuit diagram of a retrofit LED lamp
driven by a magnetic ballast, in accordance with an embodiment of
the present invention. The AC main supply 402 is supplied as an
input to the magnetic metal halide ballast 404. The output from the
magnetic metal halide ballast 404 is then fed as an input to a
bridge rectifier 306 that converts the AC waveform 302 generated by
the magnetic ballast 404 to a single sided waveform. The capacitor
310 is placed in line with the output from the magnetic metal
halide ballast 404.
* * * * *