U.S. patent application number 14/180847 was filed with the patent office on 2014-08-07 for methods of forming direct and decorative illumination.
The applicant listed for this patent is Anthony Catalano, Daniel J. Harrison. Invention is credited to Anthony Catalano, Daniel J. Harrison.
Application Number | 20140218914 14/180847 |
Document ID | / |
Family ID | 46126550 |
Filed Date | 2014-08-07 |
United States Patent
Application |
20140218914 |
Kind Code |
A1 |
Catalano; Anthony ; et
al. |
August 7, 2014 |
METHODS OF FORMING DIRECT AND DECORATIVE ILLUMINATION
Abstract
In various embodiments, direct illumination is provided from a
primary light emitter and decorative illumination is provided from
a secondary light emitter illuminating a shade.
Inventors: |
Catalano; Anthony; (Boulder,
CO) ; Harrison; Daniel J.; (Nederland, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Catalano; Anthony
Harrison; Daniel J. |
Boulder
Nederland |
CO
CO |
US
US |
|
|
Family ID: |
46126550 |
Appl. No.: |
14/180847 |
Filed: |
February 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13325473 |
Dec 14, 2011 |
8746930 |
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14180847 |
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13093197 |
Apr 25, 2011 |
8632215 |
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13325473 |
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|
12546377 |
Aug 24, 2009 |
7946730 |
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13093197 |
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|
11868406 |
Oct 5, 2007 |
7597456 |
|
|
12546377 |
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10893727 |
Jul 16, 2004 |
7296913 |
|
|
11868406 |
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60517130 |
Nov 4, 2003 |
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Current U.S.
Class: |
362/235 |
Current CPC
Class: |
H05B 45/40 20200101;
Y02B 20/30 20130101; H05B 45/10 20200101; F21V 7/0008 20130101;
F21Y 2113/20 20160801; F21K 9/64 20160801; F21W 2121/00 20130101;
F21V 13/02 20130101; F21K 9/233 20160801; F21Y 2105/10 20160801;
H01L 25/0753 20130101; Y02B 20/383 20130101; F21Y 2107/00 20160801;
H01L 2224/48091 20130101; F21V 2200/40 20150115; H05B 45/37
20200101; F21K 9/60 20160801; F21V 1/12 20130101; F21V 3/12
20180201; F21V 29/83 20150115; F21Y 2115/10 20160801; H01L 33/58
20130101; F21K 9/61 20160801; H01L 2224/48091 20130101; H01L
2924/00014 20130101; H01L 2224/48091 20130101; H01L 2924/00
20130101 |
Class at
Publication: |
362/235 |
International
Class: |
F21V 1/12 20060101
F21V001/12; F21K 99/00 20060101 F21K099/00; F21V 13/02 20060101
F21V013/02 |
Claims
1.-16. (canceled)
17. A method of illumination from a light source comprising a
primary light emitter, a secondary light emitter different from the
primary light emitter, and a shade, the method comprising:
providing direct illumination from the primary light emitter by
transmitting light emitted by the primary light emitter through a
first portion of the shade substantially without modification of
the light emitted by the primary light emitter; illuminating a
second portion of the shade, different from the first portion, with
light from the secondary light emitter; modifying the light
illuminating the second portion of the shade; and transmitting the
modified light through the second portion of the shade, thereby
forming at least a portion of decorative illumination emitted in a
direction different from a direction of the direct
illumination.
18. The method of claim 17, wherein the shade is disposed around
and spaced apart from the secondary light emitter.
19. The method of claim 17, wherein the shade is disposed around
and spaced apart from the primary light emitter.
20. The method of claim 17, wherein modifying the light
illuminating the second portion of the shade comprises at least one
of blocking a portion of the light from the secondary light
emitter, reflecting a portion of the light from the secondary light
emitter, or diffracting a portion of the light from the secondary
light emitter.
21. The method of claim 17, wherein the first portion of the shade
is substantially transparent.
22. The method of claim 17, wherein providing direct illumination
comprises emitting at least a portion of light from the primary
light emitter through an opening in the shade.
23. The method of claim 17, wherein the primary light emitter
comprises at least one light-emitting diode.
24. The method of claim 17, wherein the secondary light emitter
comprises at least one light-emitting diode.
25. The method of claim 17, wherein the direct illumination is
distinct from the decorative illumination in terms of at least one
of intensity or color.
26. The method of claim 17, wherein a shape of the shade
corresponds to at least a portion of a shape of an incandescent or
halogen light bulb the light source is designed to replace.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 13/093,197, filed on Apr. 25, 2011, which is a
continuation-in-part of U.S. patent application Ser. No.
12/546,377, filed on Aug. 24, 2009, now U.S. Pat. No. 7,946,730,
which is a continuation of U.S. patent application Ser. No.
11/868,406, filed on Oct. 5, 2007, now U.S. Pat. No. 7,597,456,
which is a division of U.S. patent application Ser. No. 10/893,727,
filed on Jul. 16, 2004, now U.S. Pat. No. 7,296,913, which claims
priority to and the benefit of U.S. Provisional Patent Application
No. 60/517,130, filed on Nov. 4, 2003. The entire disclosure of
each of these applications is hereby incorporated herein by
reference.
TECHNICAL FIELD
[0002] In various embodiments, the present invention relates
generally to illumination systems and methods incorporating light
emitting diodes (LEDs), and more specifically to such systems and
methods that provide both direct illumination and decorative
illumination.
BACKGROUND
[0003] Currently lighting applications are dominated by
incandescent lighting products. Because they use hot filaments,
these products produce considerable heat, which is wasted, in
addition to visible light that is desired. Halogen-based lighting
enables filaments to operate at a higher temperature without
premature failure, but again considerable non-visible infrared
light is emitted, and this heat is directed away from the lamp to
the extent feasible. This is conventionally done by using a
dichroic reflector shade that preferentially passes the infrared as
well as a portion of the visible light. The nature of this dichroic
reflector is such that it passes several different visible colors
as well as the infrared radiation, giving a somewhat pleasing
appearance. This has led to numerous decorative applications for
such halogen lights. These lights consume substantial current and
dissipate considerable unwanted heat. Halogen bulbs are designed to
operate at a variety of voltages between 12 volts (V) to as high 15
V or greater.
[0004] Light emitting diodes have operating advantages compared to
ordinary incandescent and halogen lights. LEDs typically emit a
narrow range of wavelengths, thereby eliminating, to a large
degree, wasted non-visible energy. White light can be created by
combining light colors. LEDs can also emit in the ultraviolet
wavelength range, in which case white light (as well as certain
colors) can be created by excitation of a phosphor.
[0005] LEDs have an extremely long life compared to incandescent
and halogen bulbs. Whereas incandescent and halogen bulbs may have
a life expectancy of 2000 hours before the filament fails, LEDs may
last as long as 100,000 hours, and 5,000 hours is fairly typical.
Moreover, unlike incandescent and halogen bulbs, LEDs are not
shock-sensitive and can withstand large forces without failure,
while the hot filament of an incandescent or halogen bulb is prone
to rupture.
[0006] Halogen bulbs, incandescent bulbs, and LEDs all typically
require a fixed operating voltage and current for optimal
performance. Too high an operating voltage causes premature
failure, while too low an operating voltage or current reduces
light output. Also, the color of incandescent and halogen lights
shifts toward the red end of the visible spectrum as current and
voltage are reduced. This is in contrast to LEDs, in which only the
intensity of the light is reduced. Furthermore, as the voltage to
an incandescent or halogen light is reduced, its temperature drops;
as a result, its internal resistance decreases, leading to higher
current consumption but without commensurate light output. In cases
where batteries are used as the source of energy, they can be
drained without producing visible light.
[0007] Incandescent and halogen bulbs require a substantial volume
of space to contain the vacuum required to prevent air from
destroying the filament, to keep the glass or silica envelope from
overheating, and to insulate nearby objects from the emitted heat.
In contrast, LEDs, as solid-state devices, require much less space
and generate much less heat. If the volume of an incandescent or
halogen bulb is allocated to a solid-state LED light, considerably
more functions may be incorporated into the lighting product.
[0008] Unlike incandescent and halogen lights, LEDs ordinarily
produce light in a narrow, well-defined beam. While this is
desirable for many applications, the broad-area illumination
afforded by incandescent and halogen lights is also often
preferred. This is not easily accomplished using LEDs. The light
produced by incandescent and halogen lights that is not directed
towards the target performs a useful function by providing
ancillary illumination and a decorative function. Halogen lights
with their dichroic reflectors do this necessarily, but ordinary
incandescent lights can employ external shades, not part of the
light bulb, in a variety of artistic designs to make use of this
otherwise misdirected light.
SUMMARY
[0009] Embodiments of the present invention overcome the
limitations of halogen or incandescent light sources, and combine
their desirable properties with the advantages afforded by LEDs
into a unique system. Various embodiments include systems and
methods that provide direct illumination as well as decorative
illumination distinct from the direct illumination.
[0010] Embodiments of the present invention therefore include an
LED-based light emitter (which includes one or more LEDs) for
replacing standard incandescent and halogen bulbs for a wide
variety of purposes. In accordance with various embodiments,
lighting systems have enhanced functionality compared to that of
conventional incandescent- or halogen-based lighting systems, and
typically include a decorative illumination element that provides,
e.g., decorative illumination distinct from the direct illumination
from the light emitter.
[0011] Some embodiments include an electrical connector or base the
same as or equivalent to a standard bulb base, a printed circuit
board (or other circuit substrate or module) electrically connected
to the base, a driving circuit that may be mounted on or embodied
by the printed circuit board, and/or one or more LEDs of one or
more colors that may be attached to the printed circuit board. The
driving circuit may include or consist essentially of a solid-state
circuit that regulates the voltage and current available from the
electrical source (e.g., a power socket) and regulates the output
to a constant value utilized by the LEDs. The available source
voltage may be either greater than or less than that utilized by
the LEDs.
[0012] Various embodiments of the present invention include an LED
lamp that replaces incandescent and/or halogen lamps as well as
their decorative shades by including LEDs on both sides of a
printed circuit (PC) board, where the decorative LEDs may be on the
opposite side of that intended for direct illumination. Similarly,
embodiments of the present invention may incorporate decorative
LEDs that are "aimed" in a direction different from those intended
for direct illumination. The decorative LEDs may, for example,
illuminate an envelope or shade around the lamp. The terms
"envelope" and "shade" are utilized herein interchangeably; the
envelope or shade may be, unless otherwise indicated, substantially
transparent or translucent. One or more portions of the shade may
incorporate a phosphor for converting at least a portion of the
light emitted by one or more of the LEDs (i.e., decorative LED(s),
direct-illumination LED(s), or both) to another wavelength. As used
herein, "phosphor" refers to any material that shifts the
wavelength of light irradiating it and/or that is luminescent,
fluorescent, and/or phosphorescent.
[0013] Lighting systems in accordance with various embodiments may
also include additional circuitry, e.g., to allow remote control of
lighting functions via an infrared or wireless device; to change
the color of either or both of the (decorative) shade illumination
and the direct-illumination LEDs; to impart a time-varying color
and/or intensity to the (decorative) shade illumination and/or the
direct illumination; to enable external switching via mechanical
action of color, pattern, and/or intensity on either the shade or
direct illumination; and/or to enable the switching of the various
functions of color, intensity, and/or pattern by interrupting the
power to the circuit within a predetermined time interval.
[0014] Mechanisms such as mechanical actuators that alter the
pattern and color of light to the shade for the purpose of
decorative illumination may also be included. Such mechanisms may
be or include a shadow screen, a multi-faceted mirror, or other
reflective or diffractive optical component or components either
fixed within the envelope of the lighting unit or which are
configured to move in order to vary the pattern and/or color of the
resulting light for decorative and/or direct-illumination
purposes.
[0015] Various embodiments of the present invention feature one or
more additional light emitters such as LEDs disposed within the
envelope (housing) of the light bulb to provide the decorative
illumination. A separate, secondary circuit may be used to produce
a constant current for the additional, decorative light emitter(s)
and control their decorative illumination characteristics such as
intensity, color, pattern, and/or frequency. The secondary circuit
may be connected to the main source of power. Light generated from
the decorative light emitter(s) may be guided along at least a
portion of the length of an optical component and exit the housing
through openings on the shade of the housing. Such embodiments may
include a secondary optical element to direct light generated by
the light emitter for direct illumination (e.g., the
primary-illumination LED(s)) to provide the decorative
illumination. A heat sink may be thermally connected to any or all
of the light emitters for regulation of their temperature. A
circuit may provide remote control of lighting functions of the
lighting system (e.g., the decorative light emitter(s)) via, e.g.,
an infrared or wireless device.
[0016] One or more optical components may be disposed within the
housing, and may direct a first, larger (e.g., more intense)
portion of light generated by the light emitter(s) for direct
illumination and direct a second, smaller (e.g., less intense)
portion of light for decorative illumination. The second portion of
light may be guided along the length of a secondary optical
component and exit the housing through one or more openings on the
shade of the housing. In an alternative embodiment, the decorative
illumination is achieved by light emission through a plurality of
light paths connecting the housing and the optical component that
directs the second portion of light from the light emitter.
[0017] In an aspect, embodiments of the invention feature an
illumination device including or consisting essentially of a
primary light emitter for providing direct illumination, a
secondary light emitter (different from the primary light emitter)
for providing decorative illumination in a direction different from
a direction of the direct illumination, and an envelope spaced away
from and disposed around at least the secondary light emitter. The
envelope receives light emitted by the secondary light emitter, the
received light forming the decorative illumination.
[0018] Embodiments of the invention include one or more of the
following in any of a variety of combinations. The device may
include an electrical connector for receiving power from an
external source. A circuit may regulate the power from the external
source and provide the regulated power to the primary and/or
secondary light emitters. The shape of the envelope may correspond
to at least a portion of the shape of an incandescent or halogen
light bulb the illumination device is designed to replace. The
primary light emitter may include or consist essentially of one or
more light-emitting diodes. The secondary light emitter may include
or consist essentially of one or more light-emitting diodes. The
direct illumination may be distinct from the decorative
illumination in terms of intensity and/or color. The envelope may
incorporate an optical element for modifying light from the
secondary light emitter. The optical element may include or consist
essentially of a mask for blocking a portion of the light from the
secondary light emitter, a reflective element for reflecting light
from the secondary light emitter, and/or a diffractive element for
diffracting light from the secondary light emitter.
[0019] The envelope may include a phosphor (e.g., either therein or
thereon, for example in the form of a layer applied to the
envelope) for converting a wavelength of light from the secondary
light emitter to a different wavelength. The decorative
illumination may include or consist essentially of only light
converted by the phosphor. The decorative illumination may include
or consist essentially of a mixture of unconverted light emitted by
the secondary light emitter and light converted by the phosphor.
The envelope may define an opening through which at least a portion
of the direct illumination is emitted. A portion of the envelope
may be configured to receive light from the primary light emitter,
and the received light from the primary light emitter may form the
direct illumination exiting the envelope. The portion of the
envelope configured to receive light from the primary light emitter
may be substantially transparent. The portion of the envelope
configured to receive light from the primary light emitter may
include a phosphor for converting a wavelength of light from the
primary light emitter to a different wavelength. The direct
illumination may include or consist essentially of only light
converted by the phosphor and exiting the envelope. The direct
illumination may include or consist essentially of, exiting the
envelope, a mixture of unconverted light emitted by the primary
light emitter and light converted by the phosphor. At least a
portion of the envelop may be removable from the primary and
secondary light emitters, thereby enabling replacement with at
least a portion of a second envelope having a different
light-transmission property (e.g., transmissivity, opacity, and/or
presence of an optical element for blocking, reflection, and/or
refraction).
[0020] In another aspect, embodiments of the invention feature a
method of illumination from a light source including a primary
light emitter and a secondary light emitter different from the
primary light emitter. Direct illumination is provided from the
primary light emitter, and a shade is illuminated with light from
the secondary light emitter, thereby forming decorative
illumination emitted in a direction different from a direction of
the direct illumination.
[0021] Embodiments of the invention include one or more of the
following in any of a variety of combinations. The shade may be
disposed around and spaced apart from the secondary light emitter.
The shade may be disposed around and spaced apart from the primary
light emitter. The shade may include a phosphor. Illuminating the
shade may include or consist essentially of converting a wavelength
of light from the secondary light emitter to a different
wavelength, the converted light exiting the shade and forming at
least a portion of the decorative illumination. The decorative
illumination may consist essentially of the converted light (i.e.,
rather than incorporating any unconverted light). The decorative
illumination may include or consist essentially of a mixture of the
converted light and unconverted light from the secondary light
emitter. Illuminating the shad may include or consist essentially
of blocking a portion of the light from the secondary light
emitter, reflecting a portion of the light from the secondary light
emitter, or diffracting a portion of the light from the secondary
light emitter.
[0022] Providing direct illumination may include or consist
essentially of illuminating a portion of the shade with light from
the primary light emitter. The portion of the shade illuminated
with light from the primary light emitter may be substantially
transparent, and the direct illumination may include or consist
essentially of light transmitted through the portion of the shade.
The portion of the shade illuminated with light from the primary
light emitter may include a phosphor, and illuminating the portion
may include or consist essentially of converting a wavelength of
light from the primary light emitter to a different wavelength, the
converted light exiting the shade and forming at least a portion
(or even all) of the direct illumination. The direct illumination
may consist essentially of the converted light exiting the shade.
The direct illumination may include or consist essentially of,
exiting the shade, a mixture of the converted light and unconverted
light from the primary light emitter. Providing direct illumination
may include or consist essentially of emitting at least a portion
of light from the primary light emitter through an opening in the
shade. The primary light emitter may include or consist essentially
of one or more light-emitting diodes. The secondary light emitter
may include or consist essentially of one or more light-emitting
diodes. The direct illumination may be distinct from the decorative
illumination in terms of intensity and/or color.
[0023] These and other objects, along with advantages and features
of the invention, will become more apparent through reference to
the following description, the accompanying drawings, and the
claims. Furthermore, it is to be understood that the features of
the various embodiments described herein are not mutually exclusive
and can exist in various combinations and permutations. As used
herein, the terms "substantially" and "approximately" mean.+-.10%,
and, in some embodiments, .+-.5%. The term "consists essentially
of" means excluding other materials that contribute to function,
unless otherwise defined herein. Nonetheless, such other materials
may be present, collectively or individually, in trace amounts.
Unless otherwise indicated, herein the terms "envelope" and "shade"
are utilized interchangeably.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In the drawings, like reference characters generally refer
to the same parts throughout the different views. Also, the
drawings are not necessarily to scale, emphasis instead generally
being placed upon illustrating the principles of the invention. In
the following description, various embodiments of the present
invention are described with reference to the following drawing, in
which:
[0025] FIG. 1 illustrates various views of an exemplary halogen
illumination device referred to commonly as an MR-16.
[0026] FIG. 2 illustrates various view of an embodiment of the
present invention that can retrofit the halogen illumination device
and contains LEDs for illumination on one side and LEDs for direct
illumination on the other. Circuitry to enable regulation and other
features is also shown.
[0027] FIG. 3 illustrates various views of an embodiment of the
present invention in which high intensity LEDs are placed on both
sides to produce shade illumination and direct illumination. A
switch and circuitry for changing the attributes of the lighting is
also shown.
[0028] FIG. 4 illustrates various views of another embodiment of
the present invention in which a movable, multifaceted mirror is
included on the shade side of the illumination unit to provide a
variable pattern on the shade.
[0029] FIG. 5A illustrates various views of another embodiment of
the present invention in which an internal fixture containing
apertures is included to pattern illumination to the shade.
[0030] FIG. 5B is a sectional view of another embodiment of the
present invention in which an additional LED is disposed within the
housing to produce decorative illumination.
[0031] FIG. 5C is a sectional view of another embodiment of the
present invention in which decorative illumination arises from an
optical component that directs light generated from the primary
light emitter.
[0032] FIG. 5D is a sectional view of another embodiment of the
present invention in which a plurality of the light paths,
connecting the housing and the optical component, direct a portion
of the light from the primary light emitter for decorative
illumination.
[0033] FIG. 5E is a sectional view of another embodiment of the
present invention in which decorative illumination arises from the
illumination of a shade featuring a phosphor.
[0034] FIG. 6 shows elevational and top views of a means for
producing a series/parallel circuit comprised of individual LED
semiconductor chips on a circuit board that results in a
high-density lighting array.
[0035] FIG. 7 shows elevational and top views of an embodiment of
the high-density LED array coupled with an integrated lens array
that is movable to produce variable-directional lighting.
[0036] FIGS. 8(a) and 8(b) schematically illustrate a
constant-current implementation of a compact dc/dc boost converter
with a feature that enables current regulation of LEDs based on the
thermal environment.
[0037] FIGS. 9(a) and 9(b) schematically illustrate a compact
constant-current buck/boost circuit for current regulation based on
the thermal environment in accordance with various embodiments of
the invention.
DETAILED DESCRIPTION
[0038] FIG. 1 illustrates an incandescent halogen-type bulb
commonly available. The features of this bulb derive from its
operating characteristics: it operates at high temperatures; it
requires an evacuated envelope separated from the hot filament; it
emits large quantities of infrared radiation experienced by the
user as heat; and it consumes large quantities of electrical power.
Nonetheless, these devices are in common usage and fixtures and
appliances have been constructed to accommodate the form, fit, and
function of these bulbs. This particular unit is a model MR-16.
[0039] The essential components of the bulb include a connector 101
that attaches to a standard source of electrical power (e.g., a
power socket) that has a mating adapter; an evacuated transparent
capsule 102 containing the hot filament 105; an envelope 103 that
acts as a shade and filter to allow infrared radiation to pass,
while reflecting a portion of the desirable visible light to the
objects below; and a transparent front cover 104 that allows the
radiation to pass, while protecting the evacuated capsule 102 from
breakage.
[0040] FIG. 2 illustrates an embodiment of the current invention.
This illuminating device preferably has the same form, fit and
function as the incandescent illumination device of FIG. 1 and as
such has a similar electrical connector 201 and similarly shaped
transparent or translucent envelope 202. The envelope 202 will
generally act to scatter light emitted from inside the envelope and
be visible from the outside. As such, the envelope 202 may serve as
a screen onto which are projected and displayed images, colors or
other decorative or information-containing light either visible to
humans or at shorter or longer wavelengths. The decorative or
informational content may be generated by circuitry contained on
one or more circuit boards 206 within the envelope of the bulb 202.
This circuit 206 in its simplest form controls other illumination
devices such as, e.g., the LEDs 207 located on the back of the
circuit board 204. Another circuit 205 may be used to control
high-power LEDs 209 in an array 208 for direct illumination of
objects outside the envelope of the lighting device. However, this
circuit or circuits may enable several useful features, including
(i) a timer to adjust the color and illumination level according to
some preset or user-adjustable schedule, (ii) a photocell to turn
the light on or off depending on the ambient light level and or a
proximity sensor, (iii) a signaling function that communicates with
other lights, and/or (iv) a user-accessible switch that enables
switching of illumination characteristics such intensity, color,
and/or continuous or flashing illumination modes.
[0041] Also typically located on circuit board 204 is a
power-conditioning circuit 205 that regulates power to the
high-intensity LEDs 208 located on the underside of the board. This
circuit adapts and controls the power available via the connector
201 and conducted to the board via wires 203. The circuit 205 may
contain storage features including a battery to enable the lighting
device to act as an emergency light source in the event of a power
failure. The circuit may rectify AC power to DC to suit the desired
current and voltage required by the series and/or parallel array of
LEDs and provide power to other on-board circuitry.
[0042] In this embodiment, the LEDs 207 on the backside of the PC
board 204 may serve the function of communication and/or
decoration. For decorative purposes, the shade 202 is preferably
made of a colored or white transparent (or preferably translucent)
material such as plastic or glass that is textured to scatter
light. In this manner light from the LEDs 207 impinges on this
surface and is made more visible to the user, and may serve the
function of decoration. The shade 202 may also contain penetrations
210 to allow heat to exit the LED enclosure.
[0043] FIG. 3 illustrates a similar incandescent replacement
product. This product also contains an electrical connector 301, a
shaped translucent or transparent envelope 302 with holes 310 to
remove heat, one or more printed circuit boards 304 within the
enclosure, and means such as wires 303 to conduct electrical power
to these board(s). This embodiment has high-intensity illumination
LEDs 307 on the top surface and other high-intensity LEDs 309 in an
array 308 on the bottom surface. Unlike the product of FIG. 2,
which had small LEDs with a narrow exit beam and low intensity,
these high intensity LEDs 309 and 307 have a higher light output
(generally greater than 10 lumens), and the exit angle of the light
may range from a narrow angle to a very broad beam as desired. To
control these LEDs, additional circuitry may be required as shown
in the figure. In addition to the power-transforming circuit 305
and the control circuits 306, additional power handling circuits
311 may be included. The high-power LEDs may have one or more
colored light outputs other than white, and have different
orientations other than vertical to provide decorative illumination
above the lighting product. A switch 311 that is accessible by the
user may be used to control characteristics of operation of the
lighting product.
[0044] FIG. 4 illustrates another embodiment of the present
invention. Unlike the previous examples in which modification of
the color, intensity and pattern is performed by electrically
controlling the electrical power to individual devices of one or
more orientations and/or color, this embodiment contains a
mechanical feature for varying the intensity and/or pattern with
time. Variation is accomplished by, for example, a multi-faceted
mirror 420, operated by a miniature electric motor 421 that changes
the orientation and position of the mirror. In this way light is
reflected or diffracted to form a pattern of shapes and/or color on
the translucent or transparent envelope 402.
[0045] FIG. 5A illustrates another embodiment that includes a
patterned mask 520 (or other suitable means) that casts a shadow or
other predetermined pattern by blocking or otherwise modifying the
pattern of light emanating from the internal LEDs 507 located on
the back side of the circuit board 504. Other features from other
embodiments discussed herein may also be incorporated.
[0046] FIG. 5B illustrates another embodiment in which an
additional, separate light emitter 531 (such as, e.g., one or more
LEDs) is controlled and/or powered by a main illumination circuit
532. The light emitter 531 may be coupled to separate and dedicated
optics 533 to provide flexibility in design, as light emitter 531
is generally meant to provide decorative illumination that is
distinct from and that complements the direct illumination from the
primary illumination source 534. For example, the decorative
illumination may be different from the direct illumination at least
in terms of illumination direction, color, and/or intensity. Power
is provided via connection of a power connector 535 to an input
power source, which, for example, may be either 115 VAC or 12 VAC.
A circuit 532 is preferably used to convert the alternating voltage
to an approximately constant DC current.
[0047] Light generated by the primary illumination source 534 may
be directed by an optical component 536 (e.g., a
total-internal-reflection (TIR) optic) and exit a substantially
transparent cover 537 attached to the housing (envelope) 538 to
provide direct illumination. Electrical connector (or circuit) 539
typically connects the light emitter 531 to the circuit 532, which
may produce a smaller constant current for the decorative light
emitter 531 than that for the primary illumination source 534.
Electrical connector 539 may be connected to the main power source;
it may include or consist essentially of a resistor that limits
current to the decorative light emitter 531 and that is in parallel
to the primary illumination source 534. The circuit 539 may contain
other suitable electronics that modulate or adjust the decorative
illumination, such as the intensity, color, and/or frequency of the
decorative light emitter 531. The light from the decorative light
emitter 531 may be emitted in substantially the same direction as
light from the primary illumination source 534, but separate optics
may be utilized to accomplish the desired decorative illumination.
For example, light-guiding optics 533 may include an optical light
guide or a solid plastic pipe that directs light along its length,
creating a linear "stripe" of light down the outside of the
device.
[0048] A heat sink 540 may be thermally connected to the thermal
path of the illumination device and thus regulate the temperature
of the primary illumination source 534; the heat sink 540 may be
co-linear with the light-guiding optics 533. Characteristics of the
decorative illumination arising from light emitter 531, such as the
intensity, color, frequency, and/or pattern of the light, may be
responsive to a remote control that may be either optical (e.g.,
infrared), wireless (e.g., radio-frequency), or wired (Ethernet,
RS-232, etc.).
[0049] As described above, a backward-facing LED sharing a PCB with
a primary illumination source may be used for decorative
illumination. Furthermore, a separate light emitter, e.g., with
dedicated control and/or power circuitry, in the housing may
provide decorative illumination. In both cases, decorative
illumination is formed actively from a secondary light emitter
providing its own light.
[0050] In another embodiment of the present invention, decorative
illumination is created passively via utilization of a portion of
the light from the primary illumination source. Reflecting optics
may be used to direct light from light sources such as LEDs for
direct illumination. Such reflecting optics may be aluminized
reflectors that may have a parabolic shape to enhance the
directionality of the forward light. The optics may also include
TIR optics, which utilize the refractive index difference between
two different media to yield a reflective internal surface. TIR
optics are often very high efficiency (85-90%) compared to ordinary
metal-coated reflectors. The design of both types of reflectors is
generally intended to maximize optical efficiency with the goal of
providing the highest degree of illumination.
[0051] To provide illumination for decorative or other purposes not
involving direct illumination, embodiments of the present invention
use TIR and other reflecting optics to divert a portion of the
light from its otherwise intended path by modifying the optical
design of the TIR and other reflecting optics. A portion of light
may be "siphoned off" in a controlled way and by means of
reflection and refraction be redirected to create the decorative or
other non-direct-illumination function. The redirected light may
then be used to achieve the desired shape and color for decorative
purposes.
[0052] FIG. 5C illustrates another embodiment of the present
invention in which a drive circuit 551 converts the mains voltage
into a constant current for a primary illumination source 552
(e.g., one or more LEDs). An optic 553 (which may include or
consist essentially of, e.g., a TIR lens) may be used to direct
light generated by the primary illumination source 552. A first
portion of light generated by the primary illumination source 552
is guided for direct illumination, and a second portion of light is
guided for decorative illumination. The first portion of the light
is usually larger (i.e., more intense) than the second portion of
the light. The first portion of the light generated by the primary
illumination source 552 may be directed by the optic 553 and exit a
substantially transparent cover 554 attached to the housing
(envelope) 555 to provide direct illumination. The housing 555 may
include a shade (which may be substantially translucent) and one or
more openings 556 in an optical component 557 (e.g., an optical
waveguide that may be completely or partially transparent) through
which light may exit as decorative illumination. Other approaches
such as diffusion and filtering of the light by the optical
component 557 may be employed to further condition the light to
meet specific decorative or secondary illumination purposes.
[0053] FIG. 5D illustrates another embodiment of the invention
operating via similar principles. One or more light channels 581
may connect a housing 582 to an optical component 583 and be
utilized to produce decorative illumination therethrough. The light
channels 581 may be, e.g., substantially empty passages through the
housing, or they may be partially or substantially filled with an
optical waveguide material. A portion of the light generated by a
primary illumination source 584 (e.g., one or more LEDs) may be
directed through the light channels 581 and exit the housing 582
through complementary openings 585 on the shade of the housing 582,
rather than or in addition to exiting through cover 587 (which may
be substantially transparent). The primary illumination source 584
may be disposed on a heat sink 586 and connected to an external
source of power via an electrical connector 588.
[0054] FIG. 5E illustrates another embodiment of the present
invention in which decorative illumination is formed actively from
a secondary light emitter providing its own light. As shown, a
primary light emitter 590 (such as, e.g., one or more LEDs) emits
light to form direct illumination in one or more specified
directions. For example, the direction of direct illumination may
be substantially aligned with and/or opposite the direction of
connection between an electrical connector 591 and an external
source of power (e.g., the AC mains). The electrical connector 591
may be a screw-in-type connector, as shown, or may have other
suitable forms (as shown in, e.g., FIG. 5D).
[0055] A secondary light emitter 592 (such as, e.g., one or more
LEDs) emits light to form decorative illumination in one or more
specified directions, preferably in one or more directions
different from (or even opposite to, in the manner shown in FIG.
5A) the direction of direct illumination. In a preferred
embodiment, the secondary light emitter 592 illuminates at least a
portion of the envelope (or shade) 593 to form the decorative
illumination. As shown, the envelope 593 is preferably disposed
around at least the secondary light emitter 592 (therefore
facilitating its illumination thereby), and envelope 593 may even
be disposed around the primary light emitter 590. In other
embodiments, the primary light emitter 590 may protrude from the
envelope 593 and/or substantially not illuminate the envelope 593.
A front surface 594 of the envelope 593 may, as shown, be a portion
of a unified envelope 593, but may have properties different from
other portions of the envelope 593 (as described below).
Alternatively, the front surface 594 may correspond to the
substantially transparent cover 554 described above, and may even
be removable from the remainder of envelope 593. In some
embodiments of the invention, the front surface 594 defines one or
more openings therethrough (e.g., through which light from the
primary light emitter 590 is emitted) or is absent entirely or in
part. The envelope 593 preferably has a shape corresponding to at
least a portion (or even all) of the shape of, e.g., an
incandescent or halogen bulb being replaced. All or portions of the
envelope 593 may be configured to be removable from a module 595
housing the primary light emitter 590, secondary light emitter 592,
and/or electrical connector 591, thereby enabling the replacement
of the envelope 593 (or, e.g., front surface 594) with another
envelope 593 (or, e.g., front surface 594) having different
light-transmission properties (e.g., different level of opacity,
more or less translucent, incorporating one or more different
optical elements, and/or incorporating one or more different
phosphors). The module 595 may also incorporate various circuitry
for supplying power to and/or controlling various features of the
light emitters, as described above. The module 595 may also
incorporate a heat sink to conduct heat away from the light
emitters during operation.
[0056] As described above with respect to various embodiments of
the invention, all or portions of the envelope 593 may be
substantially translucent and/or may incorporate one or more masks
(for, e.g., blocking portions of the light from the secondary light
emitter 592), diffractive optical elements, and/or reflective
optical elements. The secondary light emitter 592 may emit light in
one or more colors different from that emitted by the primary light
emitter 590. Thus, the decorative illumination may be distinct from
the direct illumination in terms of not only direction, but also of
color, intensity, and/or pattern.
[0057] The direct and/or decorative illumination may arise from
transmission of at least a portion of the light emitted by the
primary and/or secondary light emitters respectively, as described
above. In various embodiments, the envelope 593 may incorporate a
phosphor (e.g., a plurality of phosphor particles embedded within
the matrix of material forming the envelope 593) that converts at
least a portion of the light emitted by the light emitter(s) to
another wavelength. In such embodiments, the direct and/or
decorative illumination may include or consist essentially of the
converted light emitted by the phosphor or of a mixture of the
converted light and light transmitted through the envelope 593 (or
an opening therein) without being converted (i.e., "unconverted
light"). The phosphor may include or consist essentially of
materials such as, e.g., yttrium aluminum garnet and/or other
materials known to those of skill in the art and that may be
selected for a particular application without undue
experimentation. In an exemplary embodiment, a light emitter emits
blue light, a portion of which excites the phosphor to emit yellow
light. The yellow light may be utilized as the illumination or may
mix with a portion of the unconverted blue light to form white
light.
[0058] In one embodiment of the present invention, the decorative
illumination is formed via such a phosphor excitation while the
direct illumination passes through the envelope 593 substantially
unchanged. For example, the front surface 594 of the envelope 593
may be substantially transparent or absent, while one or more
remaining portions (e.g., those portions proximate secondary light
emitter 592), or even all of envelope 593 except for the all or a
portion of front surface 594, incorporate a phosphor for wavelength
conversion of light illuminating those portions. As shown in FIG.
5E, the envelope 593 (at least portions incorporating a phosphor)
is preferably spaced away from the light emitters illuminating it.
The resulting distance between the light emitters and the phosphor
in the envelope 593 may result in a reduced operating temperature
of the phosphor, higher conversion efficiency, and/or longer
lifetime of the phosphor. The distance between the light emitters
and the phosphor (and/or other portions of the envelope 593) may be
at least partially based on the desired form factor of the bulb;
for example, as mentioned above, this form factor may substantially
correspond to a form factor of an incandescent bulb or halogen bulb
being replaced by an embodiment of the present invention. In some
embodiments, the distance between the light emitters and envelope
593 is not constrained by such design choices, and the distance
(e.g., a distance greater than that afforded by the form factor of
an existing light bulb) may be selected to reduce heat transmission
to the envelope 593 and/or to increase the uniformity of
illumination.
[0059] In various other embodiments of the present invention, only
the direct illumination is formed via phosphor excitation, and may
thus include or consist essentially of converted light or a mixture
of converted and unconverted light, or both the direct and
decorative illumination are formed via phosphor excitation. The
primary light emitter 590 may primarily or substantially entirely
excite a phosphor (e.g., in front surface 594) that is different
from one or more phosphors excited by the secondary light emitter
592. Alternatively, the primary and secondary light emitters may
excite the same phosphor(s) but may emit different colors of
unconverted light. Thus, the converted light and/or the mixture of
converted and unconverted light emitted from different regions may
be distinct in terms of color and/or intensity. Embodiments of the
present invention incorporating one or more phosphors may also
incorporate one or more other active and/or passive elements for
forming decorative light, as discussed in detail above.
[0060] It may be appreciated from these descriptions that the LEDs
used in these embodiments, though small, occupy considerable space
that limits the overall light output of the product. This is due,
at least in part, to the need to provide electrical connections to
each of the semiconductor light-emitting chips that are housed in
large packages that provide both electrical connections and a
facility for removing heat and enabling passage of useful light.
The packages also often contain a lens or mirror for shaping and
directing this light. While these packages allow some freedom of
use, they also limit the density and eliminate the ability to
integrate the functions of heat dissipation, light direction and
electrical connection. Many of these functions may be accommodated
within a printed circuit board of appropriate design for a group of
devices at the same time and within the circuit as it is
formed.
[0061] One way of improving the light density of the overall
product is to incorporate the light-emitting dies onto a suitable
patterned circuit board that contains the external circuitry needed
to power and connect the LED devices without the use of a package.
FIG. 6 illustrates such an arrangement. This embodiment includes or
consists essentially of a printed circuit board having at least a
middle portion 601 that may be the usual fiberglass core or one
that contains metals, ceramics or other materials to enhance
thermal conductivity, a top metal clad layer 603, and a bottom
cladding layer 602. It should be well understood that these top and
bottom layers can easily be patterned by such processes as etching.
A light-emitting assembly may be attached to the patterned surface
of cladding 603 by cementing it with a thermally and electrically
conducting compound, by welding it, or using any other suitable
attachment technique. The cladding 603 then may act as a thermal or
electrical conducting pathway, or both. The light-emitting assembly
may include a metal base 604 to which is bonded a semiconductor
light-emitting chip 605. This light-emitting chip 605 typically
contains a p-n junction that emits light and conducting top and
bottom surface layers for electrical and thermal contact. A
conducting wire or tab connects the top conducting member of the
junction to the opposite conducting pad on the next assembly, thus
building up a circuit that is in series. Using a different
connection scheme, but the same general approach, a parallel
connection may be assembled. By doing this, a relatively dense
build-up of light-emitting chips may be assembled using the thermal
and electrical transfer characteristics of the printed circuit
board. Furthermore, heat sinking, cooling or other components may
be attached to the board, improving performance, for example on the
back side 602 of the printed circuit board. Although not shown, it
should be understood that this connection method may be extended in
the two dimensions of the plane of the board.
[0062] Such chips as illustrated in FIG. 6 will generally emit
light in all directions. Such a distribution of light may not be
desired for many lighting applications. Therefore, a matching array
of lenses that is positioned over the light-emitting chips may be
utilized. This separation of the top lens array from the LEDs
allows the lens array to be positioned independently, so that the
light directed by the lens may be moved and/or focused by moving
the lens array in three dimensions. The movement may be controlled
via, for example, stepper motors or piezoelectric-activated motion
controllers whose support electronics are also contained on the
printed circuit board. The array of lenses may be molded from a
transparent clear or colored material with a variety of spherical
or hemispherical shapes.
[0063] FIG. 7 illustrates such an arrangement. A PC board 701
containing patterned metal traces 703 has located on its surface
light-emitting portions featuring semiconductor light-emitting
devices 705 that are mounted on bases 704. These areas are bonded
together with electrically conducting wires or strips to form a
series/parallel circuit. Positioned over the top of these
light-emitting regions is a lens array 710 into which has been
formed (by a method such molding) a matching series of optical
elements. Three such elements of two different shapes labeled 711
and 712 are shown. This lens array 710 is spaced apart from the
semiconductor array and mounted to facilitate external manipulation
in one or more of three dimensions as shown by the opposing pairs
of arrows. Hence, by moving the lens array 710, the light emitted
from the matching LED array may be directed and focused as
required, in essence steering the light beam. This may be
controlled by onboard electronics, and via remote control or such
other means as required such as proximity sensors, timers and the
like.
[0064] These lighting products generally require a source of AC or
DC current. Although LEDs utilize direct current, it is possible to
use the LEDs to rectify AC power provided the number of LEDs is
chosen to match the AC voltage. It is well understood how to
transform AC power to DC. The use of DC power as supplied by
batteries, however, may present some problems because as the
battery voltage declines under load, the current drawn by the LEDs
rapidly declines, owing to the extremely non-linear current-voltage
characteristics of the diodes. Since the light output of a LED is
typically directly proportional to current (at least in some
regimes), this means the light output rapidly declines. On the
other hand, if battery voltage exceeds a predetermined level,
heating of the semiconductor junction of the LED is excessive and
may destroy the device. Moreover, excess heat in the LED junction
may cause a condition called thermal runaway, in which the heat
raises the current drawn at a given voltage, leading to further
heating, which in turn leads to greater current draw and quickly
destroys the device. This may be a particular problem with
high-power LEDs and requires careful thermal management.
[0065] In order to help avoid this problem it may be useful to fix
the current through the LEDs rather than the voltage. Using a
battery as the source of current, however, presents a problem
because of the differing voltage and current behavior of the
battery power source and the LED load. Therefore, a circuit may be
utilized to regulate and fix the current independent of the voltage
supplied by the battery. In the case where the battery voltage is
less than the load voltage required by the series and/or parallel
LED circuit, a boost circuit as shown in FIGS. 8(a) and 8(b) may be
employed. In these circuits an integrated circuit device, IC1 801,
is used to control the charging and discharging of an inductor L1
803. This integrated circuit may be any of several that are
available such as the Texas Instruments TPS61040. After a charging
cycle, the IC switches the circuit so that the inductor L1 803 is
permitted to discharge through the load, which in this case is the
light-emitting diodes 805. The current is controlled via a feedback
resistor R1 806. The value of the resistor is chosen to fix the
maximum current that is permitted to flow through the load, which
in this case, is one or more LEDs (LED1, LED2) indicated at 805.
This manner of control occurs because the voltage drop across R1
806 is compared to an internally generated reference voltage at pin
FB of IC1 801. When the two voltages are equal the current is
considered fixed and will be held to that predetermined value. A
diode D3 802 is used to ensure protection of the IC1 801 in case
the battery source (not shown) is connected backwards. The diode
804 allows current flow through the LEDs 805 in only the forward,
or light-emitting direction. In embodiments of this invention, such
a circuit may be enclosed within the envelope of the bulb.
[0066] The circuit shown in FIG. 8(b) differs from that of FIG.
8(a) in that the former contains an easy and inexpensive means of
protecting the LEDs from excessive current flow and the runaway
that results from high temperatures. In this circuit a resistor
with a positive resistance rate of change with temperature, R2 807
is placed in series with a fixed resistor. Resistor R2 is
physically located on the circuit board so as to be in the thermal
pathway of heat emanating from the LEDs 805. Therefore, when the
temperature of the LEDs 805 increases, the resistance of R2 807
also increases, and its resistance is added to that of R1 806.
Since the voltage drop across these combined resistances appears on
the feedback pin FB of IC1 801, the increased voltage is
interpreted as a request for decreased current. Hence, the natural
tendency of the LEDs 805 to draw more current, which would
ordinarily lead to the failure of the part, is averted by
introducing a self-limiting control function.
[0067] This circuit has the advantage of being very efficient and
compact and having built into it a temperature regulation that
allows the resulting system to automatically adapt to the thermal
environment in which it is placed. Because of these attributes, it
may, for example be put into a miniature lamp base of the kind used
for flashlights (e.g., a PR-type flange base).
[0068] However, one possible limitation of the circuit is that it
may only boost voltage from a lower value to a higher value
required by the LED load. Therefore, in situations where only one
LED is required, but a higher input voltage is all that is
available, the excess voltage will generally appear across the LED
even if one of the circuits in FIG. 8 are used. This may cause an
excessive current to be drawn, leading to premature failure of the
LED and/or premature draining of the battery. To solve this
problem, embodiments of the invention feature a circuit that is
preferably still compact enough to fit into a bulb or bulb base,
and that is capable of either raising or lowering the output
voltage above or below the voltage of the incoming battery or other
DC supply in order to maintain the desired current through the LED
load. The circuit will either boost the voltage if the input
voltage is lower than required by the LED or reduce the voltage if
it is higher than that required to sustain the necessary constant
current through the LED. It is understood that references to an LED
connote one or more LEDs in a series, parallel or series/parallel
circuit. Furthermore, because of the deleterious effects of
temperature, this circuit typically has the ability to regulate the
current through the LED depending on the ambient temperature. The
ambient temperature may be determined by the environment as well as
heat dissipated by the circuit and the LED.
[0069] Such a circuit is depicted in FIG. 9. This circuit utilizes
a so-called Cuk converter that is ordinarily used as an
inverting-switching voltage regulator. Such a device inverts the
polarity of the source voltage and regulates the output voltage
depending on the values of a resistor bridge. In the illustrated
embodiment, the inverter circuit has been altered so that it acts
to boost the voltage output or buck the voltage input in order to
maintain a constant current through the load represented by one or
more LEDs 905. The circuit incorporates an integrated circuit IC1
901 such as the National Semiconductor LM2611 Cuk Converter or
equivalent. In this circuit, the internal transistor of IC1 is
closed during the first cycle charging the inductor L1 902 from the
battery source indicated as Vbat. At the same time the capacitor C2
904 charges inductor L2 903, while the output current to the LEDs
905 is supplied by inductor L2 903. In the next cycle the IC1 901
changes state to permit the inductor L1 902 to charge capacitor C2
904 and L2 903 to discharge through the LEDs 905. The control of
the charging power and current through the load is performed by the
resistor network including or consisting essentially of R2 906a and
R3 907a. The overall value of these resistors together with the
current passing through the LEDs 905 from ground, sets a voltage
that appears on the feedback pin (FB) of IC1 901. Resistor 907a has
a positive temperature coefficient so that its resistance increases
with temperature.
[0070] The current may also be altered to accommodate thermal
effects such as heat dissipation by the LEDs, heat produced by the
IC1 or other circuit components and/or the ambient environmental
conditions. This is effected by a temperature-dependent resistor
R3. In FIG. 9(a), resistor R3 907a has a positive temperature
coefficient in which the resistance increases with temperature. The
additive effect of the series circuit with R2 906a means that as
temperature rises, the overall resistance of the combination does
also, leading to an increase in voltage drop. This in turn causes
IC1 to decrease the output current to the LEDs 905. In FIG. 9(b)
the resistor network includes resistors in parallel and series. In
this instance, resistors R2 and R4 906b, 908 are fixed and resistor
R3 907b is temperature-dependent with a positive temperature
coefficient. The use of a parallel arrangement allows a greater
freedom of choice of temperature dependence than a simple series
arrangement.
[0071] The terms and expressions employed herein are used as terms
and expressions of description and not of limitation, and there is
no intention, in the use of such terms and expressions, of
excluding any equivalents of the features shown and described or
portions thereof. In addition, having described certain embodiments
of the invention, it will be apparent to those of ordinary skill in
the art that other embodiments incorporating the concepts disclosed
herein may be used without departing from the spirit and scope of
the invention. Accordingly, the described embodiments are to be
considered in all respects as only illustrative and not
restrictive.
* * * * *