U.S. patent application number 12/984970 was filed with the patent office on 2012-07-05 for method of using light-emitting diode (led) lighting to illuminate the interior of microwave ovens.
This patent application is currently assigned to General Electric Company. Invention is credited to Terry Lien Do.
Application Number | 20120170247 12/984970 |
Document ID | / |
Family ID | 46380607 |
Filed Date | 2012-07-05 |
United States Patent
Application |
20120170247 |
Kind Code |
A1 |
Do; Terry Lien |
July 5, 2012 |
METHOD OF USING LIGHT-EMITTING DIODE (LED) LIGHTING TO ILLUMINATE
THE INTERIOR OF MICROWAVE OVENS
Abstract
A Light Emitting Diode light system for a domestic appliance
includes a Light Emitting Diode light panel mounted on a first wall
of the appliance. Light Emitting Diodes are mounted along a
periphery of the panel for emitting light through a first surface
of the panel. A second reflective surface is formed opposite the
first surface of the panel. A diffuser is provided for diffusing
light emitted by the Light Emitting Diodes. A power supply source
connected to the Light Emitting Diode panel for providing power to
the panel. A method of illuminating the interior of a microwave
oven includes providing a first Light Emitting Diode panel mounted
on a first wall of the microwave; providing a second Light Emitting
Diode panel mounted on the first wall of the microwave; providing a
diffuser for diffusing light emitted by the light emitting diodes;
and providing a power supply source connected to the Light Emitting
Diode panel to provide power to the panel.
Inventors: |
Do; Terry Lien; (Louisville,
KY) |
Assignee: |
General Electric Company
|
Family ID: |
46380607 |
Appl. No.: |
12/984970 |
Filed: |
January 5, 2011 |
Current U.S.
Class: |
362/92 |
Current CPC
Class: |
H05B 6/6444
20130101 |
Class at
Publication: |
362/92 |
International
Class: |
F25D 27/00 20060101
F25D027/00 |
Claims
1. A Light Emitting Diode light system for a domestic appliance,
comprising: a first Light Emitting Diode light panel mounted on a
first wall of said appliance, wherein Light Emitting Diodes are
mounted along a periphery of said light panel for emitting light
through a first surface of said panel; a second reflective surface
formed on said panel opposite said first surface; a diffuser
provided on said panel for diffusing light emitting by said Light
Emitting Diodes; and a power supply source connected to said Light
Emitting Diode panel for providing power to said panel.
2. The Light Emitting Diode light system of claim 1, further
comprising a second Light Emitting Diode light panel mounted on a
second wall of said appliance opposite said first wall.
3. The Light Emitting Diode light system of claim 2, further
comprising a third Light Emitting Diode panel mounted on said first
side wall of said appliance.
4. The Light Emitting Diode light system of claim 3, further
comprising a fourth Light Emitting Diode panel mounted on said
second side wall of said appliance.
5. The Light Emitting Diode light panel of claim 1, wherein said
diffuser comprises a lens.
6. The Light Emitting Diode light panel of claim 1, wherein said
first Light Emitting Diode panel is mounted within a cavity formed
in said first wall.
7. The Light Emitting Diode light panel of claim 2, wherein said
second Light Emitting Diode panel is mounted within a cavity formed
in said second wall.
8. The Light Emitting Diode light of claim 3, wherein said third
Light Emitting Diode system panel is mounted within a cavity formed
in said first wall.
9. The Light Emitting Diode light system of claim 4, wherein said
fourth Light Emitting Diode panel is mounted within a cavity in
said second wall.
10. The Light Emitting Diode light system of claim 1, wherein a
shield is mounted over said first Light Emitting Diode panel.
11. The Light Emitting Diode light system of claim 2, wherein a
shield is mounted over said second Light Emitting Diode panel.
12. The Light Emitting Diode light system of claim 3, wherein a
shield is mounted over said third Light Emitting Diode panel.
13. The Light Emitting Diode light system of claim 4, wherein a
shield is mounted over said fourth Light Emitting Diode panel.
14. The Light Emitting Diode light system of claim 1, wherein said
power supply source supplies a Direct Current to power said Light
Emitting Diode panel.
15. The Light Emitting diode light system of claim 1, wherein said
power supply source supplies an Alternating Current to power said
Light Emitting Diode panel.
16. The Light Emitting Diode light system of claim 1, wherein said
appliance comprises a microwave oven.
17. The Light Emitting Diode light system of claim 1, wherein said
appliance comprises a wall-mounted microwave oven.
18. The Light Emitting Diode light system of claim 1, wherein said
appliance comprises an over-the-range microwave oven.
19. A method of illuminating the interior of a microwave oven,
comprising: providing a first Light Emitting Diode panel mounted on
a first wall of said microwave oven; providing a second Light
Emitting Diode panel mounted on said first wall of said microwave
oven spaced apart from said first Light Emitting Diode panel;
providing a diffuser for each of said first and second Light
Emitting Diode panels for diffusing light emitted by said light
emitting diodes; and providing a power supply source connected to
each of said first and second Light Emitting Diode panels to
provide power to said panels.
20. The method of claim 19, further comprising the step of
providing a shield for said first Light Emitting Diode panel and a
shield for said second Light Emitting Diode panel.
21. The method of claim 19, wherein said step of providing a
diffuser comprises providing a lens.
22. The method of claim 19, wherein said step of providing a power
supply source comprises providing a Direct Current source.
23. The method of claim 19, wherein said step of providing a power
supply source comprises providing an Alternating Current
source.
24. The method of claim 19, wherein said first Light Emitting Diode
panel and said second Light Emitting Diode panel are provided on a
top wall of said microwave.
25. The method of claim 19, wherein said first Light Emitting Diode
panel and said second Light Emitting Diode panel are provided on a
bottom wall of said microwave oven.
26. The method of claim 19, wherein said first Light Emitting Diode
panel and said second Light Emitting Diode panel are provided on an
interior side wall of said microwave oven.
27. The method of claim 19, wherein said first Light Emitting Diode
panel and said second Light Emitting Diode panel are provided on a
rear cavity wall of said microwave oven.
28. The method of claim 19, wherein said first Light Emitting Diode
panel and said second Light Emitting Diode panel are provided on
the door of said microwave oven.
Description
BACKGROUND OF THE DISCLOSURE
[0001] The present disclosure relates to a method and apparatus for
improved lighting of the interior of microwave ovens. More
particularly, it relates to the use of light-emitting diodes (LEDs)
to illuminate the interior of microwave ovens.
[0002] The interior of existing microwave ovens are typically
illuminated by a small, tungsten filament appliance lightbulb,
typically of 25 watts, radiating 200 lumens, and having a life
expectancy of about 200 hours. Unfortunately, such bulbs are
vulnerable to microwaves, because the filament can receive
microwave energy which will heat the filament to destructive
levels. High oven temperatures, when added to the heating effects
of the microwaves in addition to the heating effects of the AC
current supply, can quickly raise the filament temperature above
its rated value, thus quickly burning out the bulb.
[0003] One existing way of minimizing damage to the light bulb is
to locate the lightbulb in one of the interior side walls of the
oven and to cover the bulb with a screen to prevent microwave
energy from reaching the bulb filament. A problem with this
solution is such a placement of the bulb results in a significant
reduction in the amount of available light for the cavity of the
oven.
[0004] To increase illumination using existing incandescent
lighting, lightbulbs of at least 750 watts or more would have to be
used. However, this would not be effective in view of the limited
power available for existing microwave ovens. Microwave ovens
typically are limited to 1,620 watts (13.5 amps) and any power used
by the lightbulb reduces the power needed for cooking.
[0005] The use of light emitting diode (LED) technology provides
lighting capabilities at far greater efficiency than are provided
by incandescent bulbs. Recent improvements have raised the
brightness and lighting quality of light emitting diode light
fixtures up to the standards of incandescent bulbs. However, light
emitting diodes in the light emitting diode lighting panels used in
lighting devices of various types can be susceptible to
overheating. When overheating occurs, the efficiency and lifetime
of the light emitting diodes is decreased and can result in LED
failure.
[0006] Thus, there is a need for improved lighting for the interior
of microwave ovens using Light Emitting Diode (LED) lights which
overcome the above mentioned deficiencies while providing better
and more advantageous overall results.
SUMMARY OF THE DISCLOSURE
[0007] The present disclosure provides a high-intensity
light-emitting diode (LED) light within the cooking cavity of a
microwave oven, so that the contents of the oven are fully
illuminated with an intensity sufficient to provide a good contrast
ratio for viewing the contents through the access window.
[0008] A Light Emitting Diode light system for a domestic appliance
includes a first Light Emitting Diode light panel mounted on a
first wall of the appliance. Light Emitting Diodes are mounted
along a periphery of the circular light panel for emitting light
through a first surface of the panel.
[0009] A second reflective surface is formed on the light panel
opposite the first surface. A diffuser is provided for diffusing
light emitted by the Light Emitting Diodes. A power supply source
is connected to the Light Emitting Diode panel for providing power
to the panel.
[0010] A method of illuminating the interior of a microwave oven
includes: providing a first Light Emitting Diode panel mounted on a
first wall of the microwave; providing a second Light Emitting
Diode panel mounted on the first wall of the microwave; providing a
diffuser for diffusing light emitted by said light emitting diodes
and providing a power supply source connected to the Light Emitting
Diode panel to provide power to the panel.
[0011] One aspect of the present disclosure is to provide an
improved microwave oven light source which will greatly increase
the available illumination within the oven cavity without reducing
the power available for the cooking operation of the oven.
[0012] Another aspect of the disclosure is that the LED light can
be placed in the path of the cooking microwaves without being
damaged.
[0013] The advantages to using LEDs over incandescent lighting is
that LEDs offer considerable power savings, illuminate much quicker
than incandescents, have a very long life (partly due to its solid
state technology), can illuminate with a color closer to white (as
opposed to the yellowish light that incandescent give off), as well
as present a visual appeal to the consumer.
[0014] LEDs consume very low power and do not add significant
energy usage to the appliance, thus reserving most of the energy
for cooking.
[0015] Still other aspects of the disclosure will become apparent
upon a reading and understanding of the following detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The foregoing, and additional aspects of the present
disclosure will become apparent to those of skill in the art from
the following detailed consideration of preferred embodiments
thereof, taken in conjunction with the accompanying drawing, in
which:
[0017] FIG. 1 is a perspective view of a microwave oven
illustrating a cut-away of an internal cavity with Light Emitting
Diodes (LED) panels installed on side walls therein in accordance
with a first embodiment of the present disclosure;
[0018] FIG. 2 is an enlarged plan view of one of the circular LED
panels of FIG. 1;
[0019] FIG. 2A is a side view of a circular LED panel with a
lens;
[0020] FIG. 3 is a top plan view of the top wall of the cavity of a
microwave oven illustrating LEDs mounted to a top wall of the
cavity in accordance with a second embodiment of the present
disclosure; and
[0021] FIG. 4 is a perspective view of a microwave oven with LED
panels mounted on a top wall.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] A conventional microwave oven has a front door, a rear wall,
interior side walls and a floor or bottom wall forming an interior
chamber or cavity of the oven. In existing microwaves, a standard
appliance-type tungsten filament lamp is positioned in a chamber or
panel within one or more of the side walls. The lamp is positioned
to be out of the path of microwaves within the cavity. In addition,
a screen covers the lamp within the chamber or panel.
[0023] In addition to a reduced amount of light being available
from the incandescent lamp because of its location in the chamber,
the screen reduces the available light by another 50 percent or so,
so that a 25 watt bulb effectively delivers only about 4% of its
emitted light to the oven cavity in a conventional microwave oven.
In addition, the location of the chamber is generally on a side
wall of the oven so that the contents of the oven are lit only from
the sides, so much of the incident light is not directed toward the
oven door, where the viewing window is normally located.
[0024] As used herein, the term "LED" or "LED device" is to be
understood to encompass bare semiconductor chips of inorganic or
organic LEDs, encapsulated semiconductor chips of inorganic or
organic LEDs, LED chip "packages" in which the LED chip is mounted
on one or more intermediate elements such as a sub-mount, a
lead-frame, a surface mount support, semiconductor chips of
inorganic or organic LEDs that include a wavelength-converting
phosphor coating with or without an encapsulant (for example, an
ultraviolet or violet or blue LED chip coated with a yellow, white
or other phosphor designed to cooperatively produce white light),
multi-chip inorganic or organic LED devices (for example, a white
LED device including three LED chips emitting red, green, and blue
light, respectively, so as to collectively generate white
light).
[0025] Thus, in accordance with the present disclosure, as shown in
FIGS. 1-3, the incandescent lamp is removed from chamber, and
instead a plurality of Light Emitting Diode (LED) light panels 10
are mounted to the interior side walls of the interior cavity of a
microwave oven 12. As illustrated in FIG. 1, microwave oven 12
includes top and bottom cavity walls 14, 16 and opposed side cavity
walls 18, 20, a rear cavity wall 22 and a front cavity wall 24,
with an access door 26 having a viewing window 28 formed therein. A
recess or cavity 32 is formed on each side wall 18, 20, and
preferably near the top wall 14. A lamp shield or cover 30 which is
configured to prevent microwave energy from passing through as is
known in the art is provided to cover each cavity 32. The cover
includes ventilation holes 31 for preventing overheating of the LED
lights. The location of the panels directs light L downwardly and
inwardly toward the center of the open cavity, illuminating the
interior as well as the contents of the oven.
[0026] The shield or cover 30 may be formed as an integral part of
the interior wall of the oven, or can be a separate element which
is secured in the oven by suitable adhesives, screws or other
fasteners (not shown) for easy access and replacement. A pair of
Light Emitting Diode (LED) light panels 10 is secured within each
of the side panels in cavities 32 in side walls 18, 20.
[0027] FIGS. 2 and 2A show an enlarged view of a circular LED light
panel 10. The LED panel is created by wrapping a disk-shaped light
guide panel 33 with a strip 34 of light emitting diodes 36. The
light emitting diodes 36 emit light L that enters the light guide
panel at its edge 38 in a radially inward direction.
[0028] A top surface of the LED panel has a mirrored edge 39 that
reflects light emitted by the light emitting diodes 36 of the LED
panel. The mirrored edge has a coating of a reflective material
such as a metal. The mirrored edge is preferably completely opaque
and reflective to the light L emitted by the light emitting diodes
36. Light L emitted by the light emitting diodes is reflected from
the mirrored edge and leaves the LED panel through a bottom surface
40 of the LED panel to provide light L2 below the LED panel.
[0029] As shown in FIG. 2A, the LED panel has two or more
connectors 41, 42 for connecting the LED panel to an external power
source (not shown). The connectors of the LED panel are connected
to the panel in conventional fashion (not shown).
[0030] As shown in FIG. 2, the configuration of the LED lights on
the panel is in a circular pattern, located on a printed circuit
board 60. Constant direct current (DC) is used to drive the LEDs so
that each LED has the same lighting intensity, regardless of the
voltage tolerances of the LED itself. The number of LEDs can vary
from one to up to eight LEDs as shown. Also, a diffuser such as a
lens 62 is used to help diffuse the light inside the interior of
the microwave oven. Power for the printed circuit board can be
either tapped off an existing transformer, or a separate DC voltage
power supply (not shown) may be created for this purpose. The board
would need to be harnessed to the control board of the microwave
oven.
[0031] Specifically, lens 62 distributes or disperses the light L2
exiting the LED panel as it exits the panel through the bottom
surface of the panel. The lens distributes the light emitted by the
LED panel to light interior spaces more efficiently.
[0032] A pair of LED panels are positioned within the cavities on
opposite interior side walls of the microwave cavity. FIG. 1
illustrates the light L which is dispersed from the LED panels to
illuminate the interior cavity of the oven from opposite sides of
the oven.
[0033] The color of the LEDs is preferably matched as closely as
possible to white or a suitable color that would not affect the
perceived color of the foods cooking inside. A Color Rendering
Index (CRI) is used to help quantitatively measure the "color" of
the light.
[0034] Referring to FIGS. 3 and 4, an alternate embodiment of the
present disclosure is shown in which the LED light panels are
placed on the top wall 14 of the interior cavity. LED panels 70
including a plurality of LED lights 71 and a shield 72 known in the
art configured to minimize exposure of the LED lights to microwave
energy are located at the top of the interior cavity of the
microwave oven. As shown in FIG. 4, light L3 of the LEDs shine
directly down into the interior cavity of the oven.
[0035] Considerations with the use of LED panels inside of a
microwave oven include where the LEDs are mounted and placed. The
preferable locations for the LED panels are at the top of the
interior cavity or the side walls of the interior cavity of the
oven. However, other locations for the LED panels within the oven
are contemplated by the disclosure. Heat dissipation of the LEDs is
also a concern to ensure that the heat is properly distributed away
from the LEDs to protect the LEDs from early failure. It is
important to protect the LEDs from the ambient oven environment due
to microwave energy, temperature, humidity, grease, etc. The
implementation of the LEDs should be cost effective and ensure
evenness/uniformity of light. The LEDs should make the food inside
the oven appear similar to its normal color, appearance and
texture. The LEDs can be electrically connected together in
parallel or in series, such as by a constant current method, or by
a constant/regulated voltage with a limiting resistor. Heat
dissipation would be a concern, as the interior of a microwave can
get hot and the LEDs themselves would need passive or active
heatsinking to dissipate the heat generated.
[0036] For passive heat sinking, the general principle is to attach
the LEDs to a component or assembly with a much larger surface area
than the LED in order to transfer the higher temperature heat from
the LED through the component or assembly into a lower temperature
fluid medium (such as air). The heat sink material can be made from
a variety of materials such as, but not limited to, aluminum,
aluminum alloy, or copper. Active heat sinking uses the same
principle as passive heat sinking, except the addition of a fan is
used to blow air over or through the component or assembly (heat
sink) in order to further increase the efficiency of the heat
transfer. Design considerations for passive and active heat sink
design are known to those skilled in the art.
[0037] The disclosure has been described with reference to the
preferred embodiments. Obviously, modifications and alterations
will occur to others upon reading and understanding the preceding
detailed description. It is intended that the disclosure be
construed as including all such modifications and alterations.
* * * * *