US008704456B2
(12) United States Patent
(10) Patent N0.:
(45) Date of Patent:
Shteynberg et a].
(54)
REGULATION OF WAVELENGTH SHIFT AND
PERCEIVED COLOR OF SOLID STATE
LIGHTING WITH INTENSITY VARIATION
(56)
(72) Inventors: Anatoly Shteynberg, San Jose, CA
6,441,558 B1
6,469,457 B2
DCC,” Jan. 2005, <http://www.philipslumileds.com/support/docu
(Continued)
(21) Appl. N0.: 13/741,896
Primary Examiner * Tuyet Thi V0
(74) Attorney, Agent, or Firm * Christensen O’Connor
Jan. 15, 2013
Johnson Kindness PLLC
Prior Publication Data
(57)
Jun. 6,2013
Division of application No. 11/927,084, ?led on Oct.
29, 2007, now Pat. No. 8,368,636, which is a
a full intensity level and at a selected temperature, with a ?rst
continuation-in-part of application No. 11/859,680,
a ?rst wavelength shift, and a second electrical biasing for the
?led on Sep. 21, 2007, now Pat. No. 7,880,400.
(58)
electrical biasing for the solid state lighting system producing
solid state lighting system producing a second, opposing
wavelength shift. Representative embodiments provide for
Int. Cl.
G05F 1/00
(52)
ABSTRACT
Representative embodiments of the invention provide a sys
tem, apparatus, and method of controlling an intensity and
spectrum of light emitted from a solid state lighting system.
The solid state lighting system has a ?rst emitted spectrum at
Related US. Application Data
(51)
8/2002 Muthu
10/2002 Callahan
mentati0n/applicati0n-briefs>, pp. 1-38.
U.S.C. 154(b) by 0 days.
(60)
4/2001 Lys
1/2002 Lys
Lumileds Application Brief AB27, “For LCD Backlighting Luxeon
Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
US 2013/0140989 A1
Misumi
Vitello
Crawford
Mueller
Mueller
OTHER PUBLICATIONS
Company, Dover, DE (US)
(65)
6/1991
2/1998
ll/l999
1/2000
ll/2000
(Continued)
(73) Assignee: Point Somee Limited Liability
Filed:
A
A
A
A
A
6,211,626 B1
6,340,868 B1
(US); Harry Rodriguez, Gilroy, CA
(US); Bradley M. Lehman, Belmont,
MA (US); Dongsheng Zhou, San Jose,
CA (US)
(22)
References Cited
5,026,978
5,719,474
5,994,844
6,016,038
6,150,774
Company, Dover, DE (US)
(*)
Apr. 22, 2014
U.S. PATENT DOCUMENTS
(71) Applicant: Point Somee Limited Liability
Notice:
US 8,704,456 B2
receiving information designating a selected intensity level or
(2006.01)
a selected temperature; and providing a combined ?rst elec
US. Cl.
trical biasing and second electrical biasing to the solid state
USPC ...... .. 315/291; 315/185 S; 315/307; 315/247;
lighting system to generate emitted light having the selected
315/312
intensity level and having a second emitted spectrum within a
predetermined variance of the ?rst emitted spectrum over a
Field of Classi?cation Search
USPC ....... .. 315/247, 246, 224, 225, 291, 3074326,
315/185 S
See application ?le for complete search history.
19 Claims, 16 Drawing Sheets
LE] UJNTWILBI
DIH FRAHE
REGISTER
predetermined range of temperatures.
INTENSITY
REGISTER
DIGITAL CUNTHOL All)
DEBOOE LOGIC
INTNPEAKn
a EGISTEM
n REGISTER?
CYCLE)" CW.
IEXTIIJTY
mam IJUTY
US 8,704,456 B2
Page 2
(56)
References Cited
U_S_ PATENT DOCUMENTS
6,528,934
6,636,003
6,731,079
6,788,011
6,801,003
6,806,659
6,963,175
6,975,079
6,987,787
7,014,336
7,038,398
7,038,399
7,081,722
7,088,059
7,135,824
7,161,311
7,208,713
7,598,685
B1
B2
B2
B2
B2
B1
B2
B2
B1
B1
B1
B2
B1
B2
B2
B2
B2
B1
3/2003
10/2003
5/2004
9/2004
10/2004
10/2004
11/2005
12/2005
1/2006
3/2006
5/2006
5/2006
7/2006
8/2006
11/2006
1/2007
4/2007
10/2009
Chen
Rahm
Andersen
Mueller
Schanberger
Mueller
Archenhold
Lys
Mick
Ducharme
Lys
Lys
Huynh
McKinney
Lys et al‘
Mueller
Ishiguchi
Shteynberg
7,863,829 B2
7,898,187 B1
1/2011 Sayers
3/2011 Mei
g,253,666 B2
8,410,723 B2
8/2012 Shteynberg
4/2013 Deurenberg
5%?gga
2001/0033252 A1
2002/0101395 A1
2002/0153851 A1
10/2001 Yamazaki
8/2002 Inukai
10/2002 Morgan
2003/0214725 A1
11/2003 Akiyama
2004/0245941
2005/0134197
2005/0225264
2005/0237284
A1
A1
A1
A1
12/2004
6/2005
10/2005
10/2005
2006/0202630
2006/0273236
2007/0001587
2007/0001588
2007/0024213
2007/0103086
2007/0194210
2007/0267978
2008/0012804
2009/0021178
A1
A1
A1
A1
A1
A1
A1
A1
A1
A1
9/2006
12/2006
1/2007
1/2007
2/2007
5/2007
8/2007
11/2007
1/2008
1/2009
Schrodinger
Lee
Kemp
Yaguma
Yamada
Gutbrod
Hatwar
Boroson
Shteynberg
Neudorf
Lee
Shteynberg
Kim
Furukawa
2009/0079358
2009/0079362
2009/0189547
2009/0236994
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A1
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7/2009
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Shteynberg
Shteynberg
Spartano
Deurenberg
2009/0322234 A1
2010/0164403 A1
2011/0115394 A1
12/2009 Chen
7/2010 Llu
5/2011 Shteynberg
OTHER PUBLICATIONS
International Search Report mailed Nov. 19, 2008, issued in Interna
tional Application No. PCT/US2008/076552, ?led Sep. 16, 2008, 1
page.
International Search Report mailed Dec. 1, 2008, issued in Interna
tional Application No. PCT/US2008/076587, ?led Sep. 17, 2008, 2
pages.
US. Patent
‘Apr.22,2014
5..gm*2
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US 8,704,456 B2
US. Patent
Apr. 22, 2014
Sheet 2 0f 16
SWPAVHELIANFGKTH
SWPAHVEILAFNGKTH
CURRENT LEVEL/DUTY CYCLE
US 8,704,456 B2
US. Patent
Apr. 22, 2014
Sheet 3 0f 16
US 8,704,456 B2
FIG. 3A
FIG. 3B
A
A
g
g
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g
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g 525- ....... .......
E
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US. Patent
Apr. 22, 2014
Sheet 4 0f 16
US 8,704,456 B2
FIG. 6
AL 7
a
FIG .
a=20%
HO"
7
WWW
La
7
FIG. 8
FORWARD BIASING (v on I)
‘*T
T
T -*>
Olldlilt3
t1
t2
ETA
FIG. 9
FORWARD BIASING (v OR I)
ka (Vpk)
J
|
M
fl
US. Patent
Apr. 22, 2014
Sheet 5 0f 16
US 8,704,456 B2
FIG. 10
FORWARD BIASING (v OH I) FAST SWITCHING
ka (Vpk)
T
If
Iavg |—
FIG. 11
FORWARD BIASING (v OR I)
ka (Vpk)
Iavg
FIG. 12
FORWARD BIASING (v OR I)
ka (Vpk)
TWA
US. Patent
Apr. 22, 2014
Sheet 6 0f 16
US 8,704,456 B2
FEIE;. 15?
FORWARD BIASING. ANY Ac SUPERIMPOSED 0N DC
FIG. 14
FORWARD BIASING, ANY Ac SUPERIMPOSED GM as
FIG. 15
[M (k=1)
0=1 (k=1)
n=o.as (k=1)
0=o.as M)
m
US. Patent
Apr. 22, 2014
Sheet 7 0f 16
US 8,704,456 B2
FIG. 15
ILED
ILEDi
ILEDE -------------- ---1
-------------- ---1
-* ---- --02 ---- ---B{
i
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a:
FIG. 17
02 (WITH ILED2)
02 (WITH
ILEDE)
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01 (WITH
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5
01 (WITH ILEDl)
t
US. Patent
Apr. 22, 2014
Sheet 8 0f 16
US 8,704,456 B2
FRIYS. .1E?
SELECT TWO OR MORE ELECTRICAL
./'105
BIASING TECHNIQUES WHICH PROVIDE
OPPOSING WAVELENGTH SHIFTS IN RESPONSE
TO INTENSITY VARIATION AND/0R
JUNCTION TEMPERATURE
T
CHARACTERIZE EACH TYPE/COLOR 0F LED
DEVICE IN RESPONSE T0 EACH SELECTED
ELECTRICAL BIASING TECHNIQUE AND/0H
./'110
JUNCTION TEMPERATURE
L
DETERMINE COMBINATIONS OF ELECTRICAL ,/'115
BIASING TECHNIQUES PREDICTED To RESULT
IN AN EMITTED SPECTRUM WHICH IS PERcETvEn
TO BE SUBSTANTIALLY CONSTANT 0R WITHIN
SELECTED TOLERANCE LEVEL
T
CONVERT THE COMBINATIONS OF BIASING
TECHNIQUES INTO PARAMETERS
CORRESPONDING TO SELECTABLE
INTENSITY LEVELS AND/OR
SENSED TEMPERATURE LEVELS.
AND STORE IN MEMORY
RETURN
125
1"120
US. Patent
Apr. 22, 2014
Sheet 9 0f 16
US 8,704,456 B2
FIG. 19
START: MONITOR AND/0R RECEIVE SIGNALTS)
INDICATING SELECTED INTENSITY
LEVEL AND/OR JUNCTION TEMPERATURE
I
CONTROLLER OBTAINS CORRESPONDING PARAMETERS
FROM MEMORY FOR AT LEAST TWO ELECTRICAL BIASING
TECHNIOUES WHICH PROVIDE OPPOSING WAVELENGTH
SHIFTS AT SELECTED INTENSITY LEVEL
AND/OR JUNCTION TEMPERATURE
13°
/135
I
CONTROLLER PROCESSES PARAMETERS AND
GENERATES CORRESPONDING LED DRIVING
CONTROL SIGNALS
I
CONTROLLER SYNCHRONIZES CONTROL
SIGNALS WITH LED DRIVER
I
CONTROLLER PROVIDES CONTROL SIGNALS
TO LED DRIVER TO GENERATE BIASING
COMBINATION TO OPERATE LEDS AND PRODUCE
SELECTED INTENSITY LEVEL WITH AN
EMITTED SPECTRUM WHICH IS PERCEIVED TO BE
SUBSTANTIALLY CONSTANT OR WITHIN A SELECTED
TOLERANCE LEVEL
RETURN
155
/145
/150
US. Patent
Apr. 22, 2014
I
Sheet 10 0f 16
=1> CONTROLLER
US 8,704,456 B2
US. Patent
Apr. 22, 2014
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US 8,704,456 B2
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US 8,704,456 B2
1
2
REGULATION OF WAVELENGTH SHIFT AND
PERCEIVED COLOR OF SOLID STATE
LIGHTING WITH INTENSITY VARIATION
and/or color of the generated light from LEDs is altered using
pulse-width modulated signals, at high or low voltage levels,
with a preprogrammed maximum current allowed through
the LEDs, in which an activation signal is used for a period of
time corresponding to the duty cycle of a PWM signal (with
CROSS-REFERENCES TO RELATED
APPLICATIONS
the timing signal effectively being the PWM period). See also
US. Pat. Nos. 6,528,934, 6,636,003, 6,801,003, 6,975,079,
7,135,824, 7,014,336, 7,038,398, 7,038,399 (aprocessormay
This application is a divisional of US. patent application
Ser. No. 11/927,084, ?led Oct. 29, 2007, which is a continu
control the intensity or the color by providing a regulated
current using a pulse modulated signal, pulse width modu
ation-in-part of US. patent application Ser. No. 11/859,680,
lated signals, pulse amplitude modulated signals, analog con
?led Sep. 21, 2007, now US. Pat. No. 7,880,400, the disclo
sures of which are hereby incorporated by their reference
herein.
trol signals and other control signals to vary the output of
BACKGROUND
a duty cycle of PWM), and US. Pat. No. 6,963,175 (pulse
LEDs, so that a particular amount of current supplied gener
ates light of a corresponding color and intensity in response to
amplitude modulated (PAM) control).
These methods of controlling time averaged forward cur
rent of LEDs using different types of pulse modulations, at
constant or variable frequency, by switching the LED current
Arrays of light emitting diodes (“LEDs”) are utilized for a
wide variety of applications, including for general lighting
and multicolored lighting. Because emitted light intensity is
proportional to the average current through an LED (or
20
alternatively from a predetermined maximum value toward a
through a plurality of LEDs connected in series), adjusting
lower value (including zero), creates electromagnetic inter
the average current through the LED(s) is one typical method
of regulating the intensity or the color of the illumination
ference (“EMI”) problems and also suffers from a limitation
on the depth of intensity variation. Analog control/Constant
Current Reduction (or Regulation) (“CCR”), which typically
source.
Because a light-emitting diode is a semiconductor device
25
problems, including inaccurate control of intensity, espe
that emits incoherent, narrow-spectrum light when electri
cally biased in the forward direction of its (p-n) junction, the
cially at low current levels (at which component tolerances
are most sensitive), and including instability of LED perfor
mance at low energy biasing of the p-n junction, leading to
most common methods of changing the output intensity of an
LED biases its p-n junction by varying either the forward
current (“I”) or forward bias voltage (“V”), according to the
30
FIGS. 1-3, both the PWM and CCR techniques of adjusting
brightness also result in shifting the wavelength of the light
35
used to regulate the lighting source current. Such converters
and regulators are often implemented as a single unit, and
40
Pulse width modulation (“PWM”), in which a pulse is
generated with a constant amplitude but having a duty cycle
which may be variable, is a technique for regulating average
control is used over a ?rst range of intensities, while PWM or
trol is used over a second range of illumination intensities. In
45
to the two control inputs (peak current control and PWM
technology” by Jim Williams, Linear Technology, November
control). Despite some improvement of intensity control and
color mixing of these two patents, however, the proposed
50
color changes when these techniques are executed, either as a
single analog control or as a combination of pulse and analog
controls.
intensity and color control of LEDs). In these applications for
55
light is acceptable. It has been proposed to correct this dis
tortion through substantially increasing the complexity and
cost of the control system by adding emission (color) sensors
60
the control of a processor (or other controller), the brightness
and other devices to attempt to compensate for the emission
shift during intensity regulation. See Application BriefAB 27
“For LCD backlighting Luxeon DCC” Lumiledes, January
2005, at FIG. 5.1 (Functional model of Luxeon DCC driver).
ety of modulation techniques, such as PWM current control,
analog current control, digital current control and any other
current control method or system for controlling the current.
For example, in Mueler et al., US. Pat. Nos. 6,016,038,
6,150,774, 6,788,011, 6,806,659, and 7,161,311, entitled
“Multicolored LED Lighting Method and Apparatus”, under
Depending on a quality of the light source, this wavelength
change may be tolerated, assuming the reduced quality of the
trum.
Such current control for dimming may be based on a vari
combinations of averaging techniques still do not address the
resulting wavelength shifting and corresponding perceived
modulated current control or other form of current control for
LEDs, a processor is typically used for controlling the amount
of electrical current supplied to each LED, such that a par
ticular amount of current supplied to the LED module gener
ates a corresponding color within the electromagnetic spec
Mick US. Pat. No. 6,987,787, PWM control is used in addi
tion to variable current control, to provide a much wider range
of brightness control by performing a “multiplying” function
LCDs, and ?uorescent lighting, for example. See, e. g., Appli
cation Note AN65 “A fourth generation of LCD backlighting
1995 (LCDs); Vitello, US. Pat. No. 5,719,474 (dimming of
?uorescent lamps by modulating the pulse width of current
pulses); and Ihor Lys et al., US. Pat. Nos. 6,340,868 and
6,211,626, entitled “Illumination components” (pulse width
applications, have not been particularly successful. For
example, in McKinney et al. US. Pat. No. 7,088,059 analog
pulse frequency modulation (“PFM”) control and analog con
current and thereby adjusting the emitted light intensity (also
referred to as “dimming”) of LEDs, other solid-state lighting,
emitted, further resulting in color distortions which may be
unacceptable for many applications. Various methods of
addressing such color distortions, which are perceptible to the
human eye and which can interfere with desired lighting
may be referred to equivalently as either a converter or a
regulator.
substantial wavelength shifting and corresponding color dis
tortions.
As described in greater detail below with reference to
selected LED speci?cations, which may be a function of the
selected LED fabrication technology. For driving an illumi
nation system (e. g., an array of LEDs), electronic circuits
typically employ a converter to transform anAC input voltage
(e.g., AC line voltage, also referred to as “AC mains”) and
provide a DC voltage source, with a linear “regulator” then
varies the amplitude of the supplied current, also has various
Accordingly, a need remains for an apparatus, system, and
65
method for controlling the intensity (brightness) of light
emissions for solid state devices such as LEDs, while simul
taneously providing for substantial stability of perceived
US 8,704,456 B2
3
4
color emission and control over wavelength shifting, over
wavelength shifts of a plurality of dominant peak wave
both a range of intensities and also over a range of LED
lengths for a corresponding plurality of colors (e.g., red,
junction temperatures. Such an apparatus, system, and
method should be capable of being implemented with few
components, and without requiring extensive feedback sys
green and blue) are controlled within corresponding prede
termined variances, in response to variables such as intensity,
temperature, selected color temperature (intensity and wave
tems.
length/spectra), selected lighting effects, other criteria, etc.
It should also be noted that the various references to a
“combination” of electrical biasing techniques should also be
interpreted broadly to include any type or form of combining,
SUMMARY
The representative embodiments of the present disclosure
provide numerous advantages for controlling the intensity of
as discussed in greater detail below, such as an additive super
position of a ?rst biasing technique with a second (or third or
more) biasing technique; a piece-wise superposition of a ?rst
biasing technique with a second (or third or more) biasing
light emissions for solid state devices such as LEDs, while
simultaneously providing for substantial stability of per
technique (i.e., a time interval-based superposition, with a
?rst biasing technique applied in a ?rst time interval followed
by a second (or third or more) biasing technique applied in a
second (or third or more) time interval); an alternating of a
?rst biasing technique with a second (or third or more) biasing
ceived color emission, over both a range of intensities and
also over a range of LED junction temperatures. The repre
sentative embodiments provide digital control, without
including external compensation. The representative embodi
ments do not utilize signi?cant resistive impedances in the
current path to the LEDs, resulting in appreciably lower
power losses and increased ef?ciency. The representative cur
rent regulator embodiments also utilize comparatively fewer
components, providing reduced cost and size, while simulta
20
technique; or any other pattern comprised of or which can be
decomposed into at least two or more different biasing tech
niques during a selected time interval. It should also be noted
that providing such a combination of two or more electrical
neously increasing ef?ciency and enabling longer battery life
biasing techniques will result in an applied electrical biasing
when used in portable devices, for example.
which has its own corresponding waveform which will differ
from the waveforms of the ?rst and second biasing tech
niques. For example, a combined or composite waveform
may be created by applying a ?rst biasing technique in a ?rst
A representative embodiment provides a method of con
trolling an intensity of light emitted from a solid state lighting
system, the solid state lighting having a ?rst emitted spectrum
at full intensity, with a ?rst electrical biasing for the solid state
lighting producing a ?rst wavelength shift, and with a second
electrical biasing for the solid state lighting producing a sec
ond, opposing wavelength shift. The ?rst and second wave
length shifts are typically determined as corresponding ?rst
and second peak wavelengths of the emitted spectrum. The
25
30
sponding ?rst, second and third time intervals (periods). The
resulting waveform of such a combination may be referred to
equivalently as a piece-wise or time-based superposition of
representative method comprises: receiving information des
ignating a selected intensity level lower than full intensity;
and providing a combined ?rst electrical biasing and second
electrical biasing to the solid state lighting to generate emitted
light having the selected intensity level and having a second
emitted spectrum within a predetermined variance of the ?rst
emitted spectrum. The predetermined variance may be sub
35
signals, or as a resulting electrical biasing waveform. For
example, two or more biasing techniques may be selected,
40
having ?rst and second respective waveforms, with the result
ing combination utilized to create or provide parameters
(such as operational parameters) and/ or control signals which
then operate in a lighting system to produce a third waveform
(as an instance of the resulting combination) for the electrical
electrical biasing and the second electrical biasing may be a
forward current or an LED bias voltage.
45
biasing provided to the solid state lighting. Any and all of
these different representations or instantiations may be con
sidered a resulting combination or composite waveform in
accordance with the present disclosure.
Reference to a parameter or parameters is also to be con
50
strued broadly, and may mean and include coe?icients, vari
55
ables, operational parameters, a value stored in a memory, or
any other value or number which can be utilized to represent
a signal, such as a time-varying signal. For example, one or
more parameters may be derived and stored in a memory and
utilized by a controller to generate a control signal, mentioned
such an emitted spectrum may range from a quite narrow
band (e.g., a single wavelength) to a considerably broader
the ?rst, second and third biasing techniques. The combina
tion may be represented in any number of equivalent ways, for
example, as one or more parameters, as one or more control
stantially zero or within a selected tolerance level. The ?rst
lt shouldbe noted that as used herein, the terms “spectrum”
and “spectra” should be interpreted broadly to mean and
include a single wavelength to a range of wavelengths of any
emitted light. For example, depending upon any number of
factors including dispersion, a typical green LED may emit
light primarily at a single wavelength (e. g., 526 nm), a small
range ofwavelengths (e.g., 525 .8-526.2 nm), or a larger range
of wavelengths (e. g., 522-535 nm). Accordingly, as indicated
above, the wavelength shifts referred to herein should be
measured as peak wavelengths of the emitted spectrum, and
time interval, followed by a second biasing technique in a
second time interval, followed by a third biasing technique in
a third time interval, followed by repeating this sequence of
?rst, second and third biasing techniques for the next corre
band (a range of wavelengths), depending upon the type of
above, for a lighting system which provides an electrical
solid state lighting and various other conditions. In addition,
various mixes and combinations of wavelengths are also
biasing having a third, combined waveform. Continuing with
the example, in this instance the parameters may be stored in
memory and may represent information such as duty cycle,
included, such as combinations of red, green, and blue wave
lengths, for example, each of which generally has a corre
60
sponding peak wavelength, and each of which may have the
amplitude, time period or time interval, frequency, duration,
repetition interval or repetition period, other time- or interval
various narrower or broader ranges of wavelengths described
de?ned values, and so on, as discussed in greater detail below.
above. Further, the various wavelength shifts of emitted spec
For example, time-de?ned values of amplitude and duration
tra may refer to a shift in a peak wavelength, corresponding
shifts of multiple peak wavelengths, or an overall or compos
ite shift of multiple wavelengths, as the context may suggest.
For example, in accordance with the present disclosure,
65
are representative parameters, such as 100 mV from the inter
val of 0 to l microseconds, followed by 200 mV from the
interval of l to 2 microseconds, followed by 0 mV from the
interval of 2 to 3 microseconds, which sequence may then be