Note: Descriptions are shown in the official language in which they were submitted.
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LED LIGHTING DEVICE FOR REFRIGERATED FOOD MERCHANDISING
DISPLAY CASES
This present invention relates to an LED lighting device
for use as a replacement of fluorescent lights in a light
tube fixtures mounted in refrigerated food display cases and
more specifically to an LED lighting device having reduced
energy consumption and reduce heat generation.
BACKGROUND OF THE INVENTION
For many years the lighting of the interiors of
refrigerated food merchandising display cases has been
accomplished with the use of fluorescent lighting systems.
However, fluorescent lights possess many characteristics
which constitute major disadvantages for the food store
owners. The disadvantages include the short lifetime of the
fluorescent lighting tube, low efficiency at low temperatures
approaching freezing temperatures and below freezing
temperatures, high power requirements, counter productive
heat injection within the refrigerated volume, low durability
and high electromagnetic interference which can be
detrimental to other electrical systems. In addition,
specialty versions of fluorescent lighting systems
incorporating higher intensity light and plastic shield
protection against cold temperatures are not economical and
do not prevent heat generation inside the refrigerated
volume. Moreover, the reduction in lighting intensity under
cold temperatures below zero can reach as much as 80%.
The recent innovation in lighting systems eliminates
many of these disadvantages. The use of light emitting diodes
(LEDs) in lighting systems has allowed many of the
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disadvantages of fluorescent lighting systems to be avoided.
LED lighting systems are typically low power, have a greatly
enhanced lifetime and have lower electromagnetic
interference.
A number of different principles of electrical lighting
have been developed over the years. Incandescent lighting was
the first lighting principle to receive widespread use, and
is still the most widely used lighting principle used to
date. More recently, the principle of electrically exciting a
gas to produce light emission from the gas has been used to
produce usable light in the form of fluorescent lighting
fixtures and the like.
Fluorescent lighting operates according to the principle
of ionizing a gas contained within a sealed tube. The
electrically excited gas produces light emission as it
returns to its normal energy level. The light spectrum
depends upon the type of gas within the tube, but
conventional fluorescent lighting emits light in the
ultraviolet spectrum, which is converted to visible light as
it encounters the coating within the tube and causes the
coating to fluoresce. Such fluorescent lighting also requires
a relatively high voltage to produce the required ionization
of the gas. This voltage may be provided by a starter which
provides an inductive kick when current is shut off or
reversed, the ballast serving to limit current in the arc
between the filaments, or by high voltage windings loosely
wound on the ballast itself in rapid start fluorescent
lights.
More recently, other technologies for lighting and for
use in lighting systems have been developed. The LED, or
light emitting diode, operates generally as a conventional
diode, i.e., allowing electrical current to pass through the
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device in one direction while blocking current flow in the
opposite direction. During this operation, the passage of
electrical current through special materials used as the
diode device also causes light to be emitted as the diode
reaches saturation. Through years of research, different
colors of light emission, light intensity, and other factors
have been developed and improved, such as power consumption.
A discussion of the known related art and its differences and
distinctions from the present invention, will now be
discussed.
U.S. Pat. No. 4,941,072 issued on Jul. 10, 1990 to
Masami Yasumoto et al., titled "Linear Light Source,"
describes a linear LED array and semi-cylindrical section
lens therefore. Yasumoto et al. does not disclose any
specific means for securing their lighting device in any form
of fixture, fluorescent or otherwise, and do not disclose any
form of electrical apparatus for adapting the relatively low
voltage requirements of an LED circuit to the necessarily
higher voltage of a fluorescent fixture or even conventional
line current.
U.S. Pat. No. 4,943,900 issued on Jul. 24, 1990 to Klaus
Gartner, titled "Lighting Fixture," describes a number of
miniature incandescent bulbs electrically connected in series
within a translucent tube. Gartner is directed particularly
to end attachment means for his lighting tube, with each end
connector comprising a male connector which fits into a
female socket in the end of the tube. Each end of the Gartner
tube contains only a single electrical conductor. The Gartner
lighting device is thus incompatible with a fluorescent
fixture, with its requirement for two parallel male
electrical connector pins extending from each end of the
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lighting element, as provided by the present LED replacement
device for fluorescent lighting.
U.S. Pat. No. 5,032,960 issued on Jul. 16, 1991 to
Masaaki Katoh, titled "Light Source Device With Arrayed Light
Emitting Elements And Manufacturing Therefore," describes an
LED lighting array comprising a linear group of LEDs
installed beneath a semi-cylindrical converging lens. Katoh
does not disclose any means for connecting his lighting array
electrically or physically with a lighting fixture, and does
not disclose any electrical apparatus for adapting his LED
array for use in a conventional fluorescent lighting fixture,
as provided by the present LED replacement lighting device.
U.S. Pat. No. 5,515,253 issued on May 7, 1996 to Fritz
C. Sjobom, titled "L.E.D. Light Assembly," describes a
specific lens configuration for diffusing the light produced
by an LED lighting array. Sjobom provides a plurality of LEDs
on a circuit board, and overlays the assembly with his lens.
The Sjobom LED lighting array is not installed within a
hollow translucent tube nor disposed along a solid
translucent rod, as is the case with the present LED lighting
apparatus. Moreover, Sjobom does not disclose any form of end
connectors for his lighting array, nor does he disclose any
electrical apparatus for adapting an LED array for use with
the higher voltage of a conventional fluorescent lighting
system or 110-115 volt AC supply, as provided by the present
LED replacement for fluorescent lighting invention.
U.S. Pat. No. 5,688,042 issued on Nov. 18, 1997 to
Abolfazl Madadi et al., titled "LED Lamp," describes an
elongate bulb having an attachment base at only one end
thereof. The lamp includes three elongate circuit boards,
each having a series of LEDs installed thereon. The circuit
boards are installed within the bulb to emit light in a
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general omni-directional pattern. Madadi et al. do not
provide any form of reflector or diffuser means with their
light, as they intend it to be installed within a double
faced, back lighted sign (e.g., exit signs, etc.). Moreover,
as they intend their light to be used only in such relatively
compact installations, they do not provide the conventional
double parallel pin connectors at each end of the bulb, as is
provided in the present LED replacement lighting.
U.S. Pat. No. 5,810,463 issued on Sep. 22, 1998 to
Atsushi Kawahara et al., titled "Illumination Device,"
describes an LED lighting device having either a row of LEDs
which send their light through a generally cylindrical lens
with reflectors thereon, or which may include an array of
LEDs at one end of the lens. The lens of the Kawahara et al.
lighting device includes a lateral extension, the end or edge
of which is adjacent to the linear LED array. This shape is
not compatible with installation within a conventional
fluorescent light fixture, as provided by the present
invention. Moreover, Kawahara et al. do not disclose any
electrical apparatus to provide compatibility with the
relatively high voltages of a fluorescent lighting system or
even conventional household supply current, as provided by
the present invention.
U.S. Pat. No. 6,068,383 issued on May 30, 2000 to Roger
Robertson et al., titled "Phosphorous Fluorescent Light
Assembly Excited By Light Emitting Diodes," describes a
fluorescent lighting device which produces light in the
visible spectrum by means of a fluorescent coating within the
lighting apparatus, which in turn is excited by ultraviolet
light produced by a number of LEDs within the device. The
device of the Robertson et al. is more closely related to a
conventional fluorescent lighting assembly, than to the
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present invention. The only difference between the assembly
of the Robertson et al. '383 U.S. patent and conventional
fluorescent fixtures, is that conventional fluorescent
lighting produces light in the ultraviolet spectrum by means
of ionizing a gas within a tube, with the ultraviolet light
produced by the ionized gas causing the fluorescent coating
within the tube to fluoresce to produce light in the visible
spectrum. The present invention does not produce any form of
ultraviolet light; all light produced by the LEDs used in the
present lighting apparatus, comprises light in the visible
spectrum. There is no need to convert light from the
ultraviolet spectrum to the visible spectrum, in the lighting
system of the present invention. Moreover, the Robertson et
al. '383 U.S. patent does not disclose any physical
configuration for a lighting device which enables it to be
installed within a conventional fluorescent lighting fixture,
as provided by the present LED replacement for fluorescent
lighting invention.
U.S. Pat. No. 6,139,174 issued on Oct. 31, 2000 to Mark
M. Butterworth, titled "Light Source Assembly For Scanning
Devices Utilizing Light Emitting Diodes," describes a solid
translucent rod which accepts blue light from an appropriate
LED at one end thereof, and transmits the light outwardly
through the side of the rod. A pair of fluorescent strips
along the side of the rod produce light in different spectra,
with a third strip passing the blue light therethrough. The
Butterworth light apparatus is adapted for use in a scanning
device, as are many of the lighting devices of the prior art
discussed further above. Accordingly, no means of installing
or operating the Butterworth apparatus in a conventional
fluorescent lighting fixture is disclosed.
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U.S. Pat. No. 6,283,612 issued on Sep. 4, 2001 to Mark
A. Hunter, titled "Light Emitting Diode Light Strip,"
describes an elongate translucent tube with a plurality of
LEDs installed in series therein. However, Hunter utilizes a
separate power supply to step down the voltage from the
conventional 110-220 volt supply to the reduced voltage
required even for a series of LEDs. The Hunter power supply
is a separate box, wired in series with the light by an
elongate flexible cable and removable connector. Moreover,
each end of the Hunter lamp includes a flexible cable
extending therefrom, which is not compatible for installation
in a conventional fluorescent light fixture. In addition,
Hunter does not disclose any form of light reflecting or
diffusing means for scattering the directional light of the
LEDs in a wide spread pattern, as provided by the present
invention.
U.S. Pat. No. 6,331,915 issued on Dec. 18, 2001 to
Kenneth J. Myers, titled "Lighting Element Including Light
Emitting Diodes, Microprism Sheet, Reflector, And Diffusing
Agent," describes sheet(s) of material having a series of
prismatic reflective grooves formed therein, and the
placement of LEDs along the grooves. A number of additional
means of diffusing or scattering the light emitted by the
LEDs, is also described generally by Myers. However, the only
electrical power source indicated in the Myers disclosure, is
a conventional symbol for a battery across two of the LEDs in
one of the drawing Figs. There is no description of this
battery.
U.S. Pat. No. 6,388,393 issued on May 14, 2002 to Lewis
Illingworth, titled "Ballasts For Operating Light Emitting
Diodes In AC Circuits," describes various embodiments of
inductor and transformer devices for reducing voltage and
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current to proper levels, for powering LED lighting devices
in an aircraft electrical system. Illingworth does not
describe any type of connectors for connecting an LED light
array in a fluorescent fixture, nor does he describe any
means for reflecting or diffusing the light output from an
LED array, which features are a part of the present
invention. Moreover, Illingworth is directed to relatively
low voltages, and particularly DC electrical power systems,
as used in aircraft. Accordingly, he teaches away from the
present invention, with its "drop-in" replacement in a
fluorescent lighting fixture.
None of the above discussed patented prior art, taken
either individually or in combination, is seen to describe
the present invention.
It is an important feature of the present invention to
use LEDs in a lighting fixture to benefit from its low power
consumption and apply it to refrigerated food merchandising
display cases.
LED lighting systems provide many other advantages in
the present application. LEDs are relatively cool in
operation, and do not produce any significant amount of heat
as a by product of their operation. Moreover, they are quite
efficient in comparison to other types of lighting
principles. LEDs are available in a number of different
colors, and the lighting intensity may be varied by means of
a simple variable resistor or rheostat, unlike other lighting
systems. However, even with recently developed "super bright"
LEDs, the light output of a single LED is relatively weak in
comparison to a conventional fluorescent light unit at room
temperature. Nonetheless, multiple LED assemblies in a single
unit or fixture can provide an equivalent amount of light to
a fluorescent light fixture especially at freezing
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temperatures. These advantages are discussed in an article
entitled "Refrigerated Display Case Lighting with LEDs" by
Ramesh Raghavan et al, Rensselaer Polytechnic Institute,
Troy, NY 12180.
Another feature of the present invention is to benefit
from the fact that LEDs do not generate heat and that they
are available in different colors and which features are
advantageous for use to shed light on refrigerated food in
merchandising display cases.
Another feature of the present invention is to provide a
solution to the problems of fluorescent lighting by providing
a replacement lighting unit for a fluorescent lighting tube.
The present replacement lighting units comprise two
embodiments of built-in or built-out AC/DC power conversion
and multiple LEDs. The lighting units are equipped with
support and connectors allowing installation in the
conventional fluorescent light tube fixture. The present
invention also includes the electrical components required to
adapt the operation of an LED array to the electrical system
of a fluorescent lighting fixture, with such electrical
components being provided either internally within the
replacement lighting unit (built-in) or externally (built-
out), as needed. The present invention also provides
components and controls to adjust the light intensity and
spectral output.
The present invention can be constructed in two versions
of an LED lighting unit. A first LED lighting unit version
consisting in a number of light emitting diodes (LEDs)
arranged linearly as to produce a desired light intensity
comparable to fluorescent lighting fixtures and serving as a
direct replacement for a conventional fluorescent lighting
fixture, with the present lighting device utilizing an
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integrated power converter and , a second LED lighting unit
embodiment consisting of a number of light emitting diodes
(LEDs) arranged linearly as to produce a desired light
intensity comparable to fluorescent lighting fixtures and
utilizing an external power module. The two LED lighting
units embodiment presented having LEDs disposed linearly
using a printed circuit board held by a aluminium fixture
also serving as a heat sink. The LEDs may be in a series or
parallel circuit array as desired. The circuit board 3 can
be an elongated board of two or more boards secured end-to-
end.
In one version, the aluminium fixture of the present
invention which contains the LED lighting printed circuit
board, is equipped with fluorescent light receptacle
connector pins at each end thereof, in the manner of a
conventional fluorescent tube. The power conversion
components, such as rectifier, transformer, LED light
spectrum modulation and intensity setting may be built into
the aluminium fixture located at one end of the LED lighting
unit.
In a second version, the aluminium fixture of the
present invention which contains the LED lighting printed
circuit board, is equipped with a common two pin connector at
one end, in the manner as to allow the connection of a
suitable external AC/DC power source. The LED light spectrum
modulation and intensity setting may be built into the
aluminium fixture and located at one end of the LED lighting
unit. In this present embodiment, the power conversion is
accomplished within the external AC/DC power source.
In the two versions presented, the aluminium fixture
containing the printed circuit board on which LEDs are
disposed, also contains a reflective surface allowing the LED
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light to be propagated into a set direction forming a proper
angle of projection within the refrigerated food
merchandiser. The reflective coating is produced at the time
of extrusion.
Accordingly, it is a feature of the present invention to
provide a lighting unit using the LED lighting principle and
internal power conversion for use as a direct replacement for
a fluorescent tube within refrigerated food merchandisers.
It is a further feature of the present invention to
provide a lighting unit which utilize an external AC/DC power
source as to satisfy the needs of other refrigerated food
merchandiser lighting requirements and configurations.
It is a further feature of the present invention to
provide a replacement LED lighting device including the
required electrical components for compatibility integrated
within the lighting unit, or disposed externally to the LED
lighting unit.
Still another feature of the present invention is to
provide a LED lighting device for refrigerated food
merchandisers which may include a LED light spectrum
modulation and intensity setting within a range acceptable by
food inspection authorities.
Still another feature of the present invention is to
provide a LED lighting device for refrigerated food
merchandisers which may include a LED light spectrum
modulation and intensity setting within the LED lighting unit
or at the refrigerated food merchandiser level.
According to the above features the present invention
provides an LED (light emitting diode) lighting device for
connection into end connectors of a conventional fluorescent
lighting fixture for replacement of fluorescent tubes. The
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device comprises an elongated rigid support body having pin
connectors at opposed ends thereof. The pin connectors are
each provided with a pair of electrical connecting pins
extending exteriorly thereof in a spaced-apart configuration
for operatively engaging the end connectors. Circuit board
means is secured along the rigid support body. A plurality
of LEDs are secured together and to the circuit board means.
Power conversion circuit means supplied the necessary voltage
to the LEDs connected together.
The LED lighting device of the present invention was
developed preferably, but not exclusively, for replacement of
fluorescent lighting tubes in fluorescent lighting fixtures
secured in refrigerated merchandising display cases which
displays foodstuff.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the present invention will now
be described with reference to the accompanying drawings in
which:
Figure 1 is a side elevation view of the LED lighting
device provided with an internal power source;
Figure 2 is a side elevation view of the LED lighting
device provided with an external power source;
Figure 3 is a cross sectional view of a refrigerated
food merchandising display case showing the installation of
an LED lighting device of the present invention as provided
with an internal power source;
Figure 4 is a cross sectional view of a refrigerated
food merchandising display case showing the installation of
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an LED lighting device of the present invention with an
external power source;
Figure 5 is a ballast wiring diagram of a prior art
fluorescent lamp fixture; and
Figure 6 is a wiring diagram of the lighting device of
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention discloses two embodiments of an
LED lighting device 1 adapted for installation in
refrigerated food merchandising display cases as a
replacement to a conventional fluorescent lighting fixture
tube. The present LED lighting device 1 contains multiple
light emitting diodes (LEDs) 2 therein, which provide the
desired lighting. Figure 1 of the drawings illustrate the
first embodiment LED lighting device 1 provided with an
internal power assembly 4 and as a replacement LED lighting
device 1, to a fluorescent tube of an existing conventional
fluorescent tube lighting fixture 25.
Figure 2 illustrate the configuration of the second
embodiment of the LED lighting device 1' wherein, the power
conversion assembly 14 is installed externally to the LED
lighting device by means of a connector 12 and wiring harness
13. Conventional 115 volts AC electrical source is supplied
to the power conversion assembly 14 through a connection
cable 15 connected to the conventional supply.
While referring to figure 1, the LED lighting device 1
is comprised of an aluminium fixture 5 onto which the other
components of the LED lighting device are mounted. An LED
printed circuit board 3 is mounted onto the aluminium fixture
as to allow a secure connection and to provide a heat sink
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for the heat generated by the LEDs 2 to flow into the
aluminium fixture. The LED lighting device 1 is equipped with
connector pins 6a, 6b, 7 and 8 arranged similarly to a
fluorescent tube whereby to connect to a fluorescent tube
fixture and facilitating its replacement. The connector pins
6a, 6b, 7 and 8 are connected to the power conversion
assembly 4 by means of connections part of the LED printed
circuit board 3 allowing standard fluorescent light ballast
current to flow to the power conversion unit 4 which in turns
supplies power to the LEDs 2 mounted on the printed circuit
board 3. The connector pins 6a, 6b, 7 and 8 are secured in
place by pin connectors or end cap connectors 9 and 10. End
caps 9 and 10 also secure the aluminium fixture 5 in place at
the proper position in the end connectors 26 of the
conventional fluorescent tube fixture 25 shown in phantom
lines in figure 1 as to allow LED lighting to be oriented
into a proper direction.
A plurality of light emitting diodes (LEDs) 2 are
installed onto the printed circuit board 3. The LEDs 2 are
electrically connected to the power conversion assembly 4
through the printed circuit board 3. The power conversion
assembly 4 converts the conventional fluorescent lighting
ballast high voltage output into a low voltage output
suitable to operate the LEDs.
Referring to figure 2, the second embodiment of the LED
lighting device 1 is shown. The power conversion assembly 14
is shown mounted externally of the device and is used to
convert regular 115 volt AC supply voltage to a low voltage
suitable to operate LEDs. The present embodiment is used for
new installations or new fabrication of refrigerated food
merchandising display cases.
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Referring now to figure 3 of the drawings, there is
illustrated in cross section, a refrigerated food
merchandising display cases 16 and a typical frame 17
containing the installation of a LED lighting device 1 as a
direct replacement of a fluorescent light tube in a fixture
at location 18. Conventional ballast voltage is brought to
the lighting unit through cable 22 as it would to power the
conventional fluorescent tubes. The LED lighting device 1 can
be rotated within end caps 9 and 10 (see figure 1) to provide
the best possible light projection in the area 21 by the
directional beam 20.
Figure 4 of the drawings illustrates in cross section, a
refrigerated food merchandising display case 16 and typical
frame 17 containing a new installation of a LED lighting
device 1. The LED lighting device 1' is powered by the power
conversion assembly 14 installed preferably concealed in the
structure 17 and 115 AC is brought to the power conversion
assembly 14 through cable 15. In turn, the LED lighting
device 1' is powered by low voltage supplied from the power
conversion assembly 14 through cable 13.
The LED lighting devices 1 and 1'may be comprised of
LEDs capable of variable spectral light output or
combinations of RGB assemblies (red, green and blue LEDs) to
allow the production of coloured lighting. The printed
circuit board 3 is designed to allow the installation of
multiple red, green and blue LEDs to produce light other than
pure white light. Although any arrangement of red, green and
blue LEDs will produce coloured lighting, the present
invention allows the variable spectral light production
through adjustments on the power conversion assemblies 4 and
14 and use of super bright white LEDs.
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The LED lighting devices 1 and 1' project light in an
angular beam 20 in a direction towards surface 21 that is
basically a portion of the surface of a shelf underneath that
where the LED lighting device 1 or 1' is installed. The light
projection beam 20 can be moved to maximize lighting by
turning the aluminium fixture 5 within the end caps 9 and 10.
The aluminium fixture is therefore pivotally connected
between the end caps to adjust its angular position. To
further enhance the LED lighting device performance, the
aluminium fixture 5 provides a reflection cavity 11 (see
figure 1) which is coated to enhance light reflection.
Figure 5 illustrates a typical ballast wiring diagram of
the prior art.
Figure 6 illustrates the wiring diagram for the
replacement LED lighting device of the present invention.
The use of LEDs to supply lighting for a refrigerated
food merchandising display case 16, provides numerous
advantages over fluorescent lighting systems. Among these
advantages is the ability to control the light output level
of the LED lighting devices 1 and 1' by varying the voltage
to the LEDs. This is accomplished by means of electronic
controls that form part of the power conversion assembly and
not shown herein but obvious to a person skilled in the art.
In conclusion, the present LED lighting device 1, for
use as direct replacement for fluorescent lighting tubes or
as new LED lighting device 1' for refrigerated food
merchandising display cases provides numerous advantages over
conventional fluorescent lighting units. The electrical power
requirements of LEDs lighting is 30 to 50% less in comparison
to most other forms of lighting, thereby saving energy and
increasing efficiency in comparison to other lighting forms.
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Another advantage of the present invention pertains to
the durability of the LED lighting device which is estimated
safely at 50,000 hours. Another advantage regards that of
comparative performance. LEDs are known to be more efficient
at cold temperatures than fluorescent lighting systems.
Fluorescent lighting output is greatly affected by freezing
temperatures below zero degrees. The LEDs consume less
energy, produce less heat and therefore require less energy
from the refrigeration system to maintain a substantially
stable cool temperature for the foodstuff displayed in the
display cases.
It is to be understood that the present invention
encompasses any and all modifications that fall within the
scope of the appended claims.
