U.S. patent application number 17/168402 was filed with the patent office on 2021-05-27 for systems and methods for providing color management control in a lighting panel.
The applicant listed for this patent is IDEAL Industries Lighting LLC. Invention is credited to John K. Roberts, Keith J. Vadas.
Application Number | 20210160981 17/168402 |
Document ID | / |
Family ID | 1000005381930 |
Filed Date | 2021-05-27 |
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United States Patent
Application |
20210160981 |
Kind Code |
A1 |
Roberts; John K. ; et
al. |
May 27, 2021 |
SYSTEMS AND METHODS FOR PROVIDING COLOR MANAGEMENT CONTROL IN A
LIGHTING PANEL
Abstract
Provided are systems and methods for providing a stabilized
color management system in a solid state lighting panel. Methods
according to some embodiments include receiving, in the
microcontroller, a color management reference value corresponding
to a color characteristic of the solid state lighting panel and
adjusting a control mode of the microcontroller responsive to the
color management reference value.
Inventors: |
Roberts; John K.; (Ellicott
City, MD) ; Vadas; Keith J.; (Caledonia, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IDEAL Industries Lighting LLC |
Durham |
NC |
US |
|
|
Family ID: |
1000005381930 |
Appl. No.: |
17/168402 |
Filed: |
February 5, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14464760 |
Aug 21, 2014 |
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17168402 |
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11958721 |
Dec 18, 2007 |
8823630 |
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14464760 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05B 45/20 20200101;
H05B 45/24 20200101; H05B 45/22 20200101 |
International
Class: |
H05B 45/24 20060101
H05B045/24; H05B 45/20 20060101 H05B045/20; H05B 45/22 20060101
H05B045/22 |
Claims
1. An electronic display device comprising: a liquid crystal
display (LCD) panel; a backlighting panel comprising solid state
lighting devices of differing color; a color management unit
configured to generate color management signals for controlling
chromaticity and luminance output of the solid state lighting
devices; a microcontroller; a driver for providing electrical
current to the solid state lighting devices, wherein the color
management unit provides the color management signals to the
microcontroller, the microcontroller setting a control system mode
responsive to analysis of the color management signals, the control
system mode altering chromaticity and luminance output of the solid
state lighting devices via the driver and a backlight panel
controller.
2. The electronic display of claim 1, wherein the analysis
comprises comparison of a current color management value
corresponding to a current color characteristic of the electronic
display, and a dynamic input signal value corresponding to altered
color characteristic of the electronic display.
3. The electronic display of claim 2, wherein the comparison
comprises a difference between the current color management value
and the dynamic input signal value.
4. The electronic display of claim 2, wherein the altered color
characteristic of the electronic display comprises chromaticity and
luminance of the solid state lighting devices.
5. The electronic display of claim 1, wherein the control system
mode alters the chromaticity and luminance of groups of the solid
state lighting devices.
6. The electronic display of claim 5, wherein the groups of the
solid state lighting devices are altered via pulse width
modulation.
7. The electronic display of claim 6, wherein the microcontroller
generates the pulse width modulation responsive to the analysis of
the color management signals.
8. The electronic display of claim 5, wherein the groups of the
solid state lighting devices exhibit differing chromaticity and
luminance.
9. The electronic display of claim 5, wherein the groups of the
solid state lighting devices comprise tiles of the solid state
lighting devices.
10. The electronic display of claim 5, wherein the groups of the
solid state lighting devices comprise strings of the solid state
lighting devices.
11. The electronic display of claim 1, wherein the LCD panel
comprises a two-dimensional arrangement of liquid crystal
shutters.
12. The electronic display of claim 10, wherein an LCD controller
controls an output image of the electronic display image by varying
states of the LCD shutters corresponding to different pixels of the
LCD panel.
13. The electronic display of claim 1, wherein the solid state
lighting devices are red, blue and green.
14. The electronic display of claim 1, wherein the solid state
lighting devices are light emitting diodes.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 U.S.C.
.sctn. 120 as a continuation of U.S. patent application Ser. No.
14/464,760, filed Aug. 21, 2014 which is a continuation application
of U.S. patent application Ser. No. 11/958,721, filed Dec. 18,
2007, now U.S. Pat. No. 8,823,630. The entire content of the above
application is incorporated herein by reference as if set forth in
its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to lighting, and more
particularly, to controlling a solid state lighting panel.
BACKGROUND
[0003] Solid state lighting arrays are used for a number of
lighting applications. Solid state lighting panels including arrays
of solid state lamps have been used as direct illumination sources,
for example, in architectural and/or accent lighting. A solid state
lamp may include, for example, a packaged light emitting device
including one or more light emitting diodes (LEDs). Inorganic LEDs
typically include semiconductor layers forming p-n junctions.
Organic LEDs (OLEDs), which include organic light emission layers,
represent another type of solid state light emitting device.
Typically, a solid state light emitting device generates light
through the recombination of electronic carriers, i.e. electrons
and holes, in a light emitting layer or region.
[0004] Solid state lighting panels are commonly used as backlights
for small LCD display screens, such as LCD display screens used in
portable electronic devices. In addition, there has been increased
interest in the use of solid state lighting arrays for backlights
of larger displays, such as LCD television displays.
[0005] For smaller LCD screens, backlight assemblies may employ
white LED lamps that include a blue-emitting LED coated with a
wavelength conversion phosphor that converts some of the blue light
emitted by the LED into yellow light. The resulting light, which is
a combination of blue light and yellow light, may appear white to
an observer. However, while light generated by such an arrangement
may appear white, objects illuminated by such light may not appear
to have a natural coloring, because of the limited spectrum of the
light. For example, because the light may have little energy in the
red portion of the visible spectrum, red colors in an object may
not be illuminated well by such light. As a result, the object may
appear to have an unnatural coloring when viewed under such a light
source.
[0006] The color rendering index of a light source is a qualitative
measure of the ability of the light generated by the source to
accurately illuminate a broad range of colors. The color rendering
index ranges from essentially zero for monochromatic sources to
nearly 100 for incandescent sources. Light generated from a solid
state light source may have a relatively low color rendering index,
but this can be increased through use of multiple emitters of
various color and/or by use of phosphor to broaden the emitted
spectrum.
[0007] For illumination applications, it is often desirable to
provide a lighting source that generates a white light having a
high color rendering index, so that objects illuminated by the
lighting panel may appear more natural. Accordingly, such lighting
sources may typically include an array of solid state lamps
including red, green and blue light emitting devices. When red,
green and blue light emitting devices are energized simultaneously,
the resulting combined light may appear white, or nearly white,
depending on the relative intensities of the red, green and blue
sources. There are many different chromaticities of light that may
be considered "white." For example, some "white" light, such as
light generated by incandescent lamps, may appear more yellowish,
while other "white" light, such as light generated by some
fluorescent lamps, may appear more bluish in color.
[0008] Solid state lamps, such as LED's, are current-controlled
devices in the sense that the intensity of the light emitted from
an LED is related to the amount of current driven through the LED.
One common method for controlling the current driven through the
solid state lamps to achieve desired intensity and color mixing is
a Pulse Width Modulation (PWM) scheme. Many PWM schemes may pulse
the solid state lamps alternately to a full current "ON" state
followed by a zero current "OFF" state.
[0009] Designing a management control system that provides
accuracy, uniformity and/or responsiveness may be difficult using
conventional control system methodologies. For example, while a
color management control system may produce undesirable output
oscillations corresponding to, for example, sensor output noise,
placing a filter on a sensor output may reduce control system
responsiveness and cause oscillations from filter phase lag.
SUMMARY
[0010] Some embodiments of the present invention may provide
methods of controlling a solid state lighting panel utilizing a
microcontroller. In some embodiments, the methods may include
receiving, in the microcontroller, a color management reference
value corresponding to a color characteristic of the solid state
lighting panel and adjusting a control mode of the microcontroller
responsive to the color management reference value.
[0011] In some embodiments, adjusting a control mode includes
operating the microcontroller in a closed loop control mode
responsive to receipt of the color management reference value until
the solid state lighting panel reaches a color characteristic
target value corresponding to the color management reference value
and operating the microcontroller in an open loop control mode when
the solid state lighting panel substantially reaches the color
characteristic target value. In some embodiments, the color
management reference value includes a user input value.
[0012] Some embodiments may include estimating a color management
change value as a difference between the color management reference
value and a current color management value corresponding to a
current color characteristic of the lighting panel and generating,
if the color management change value is greater than a threshold
value, an incremental value between the color management reference
value and the current color management value. In some embodiments,
the color management reference value includes a value from a
calibration system and/or supervisory controller.
[0013] Some embodiments may include periodically operating the
microcontroller in a closed loop control mode to correct for color
characteristic drift. In some embodiments, the color characteristic
includes lighting panel luminance. In some embodiments, the color
characteristic includes a lighting panel chromaticity value.
[0014] Some embodiments of the present invention may provide a
lighting panel system. Embodiments of such a system may include a
lighting panel including multiple solid state lighting devices
configured to be driven by multiple current drivers and a
multi-mode color management system that is configured to control
the lighting panel via the current drivers. The multi-mode color
management system may be further configured to selectively operate
in a closed loop control mode responsive to a dynamic input signal
value.
[0015] In some embodiments, the multi-mode color management system
includes a color management unit that is configured to receive
sensor input from multiple lighting panel sensors. The color
management unit may be further configured to generate color
management information to control light output of the multiple
solid state lighting devices.
[0016] In some embodiments, the multi-mode color management system
includes a microcontroller that is configured to receive color
management information from a color management unit and the dynamic
input signal value from a user input, wherein the dynamic input
signal value corresponds to a color characteristic of the lighting
panel.
[0017] In some embodiments, the color characteristic of the
lighting panel includes a solid state lighting panel luminance
output. In some embodiments, the color characteristic of the
lighting panel includes a solid state lighting panel chromaticity
output.
[0018] In some embodiments, the multi-mode color management system
includes a mode selection module that is configured to estimate a
color management change value, compare the color management change
value to a threshold value, and set a microcontroller to a closed
loop control mode if the color management change value is greater
than the threshold value. In some embodiments, the mode selection
module is further configured to set the microcontroller to an open
loop control mode if the color management change value is less than
the threshold value.
[0019] In some embodiments, the color management change value
includes a difference between the dynamic input signal value and a
current color management value.
[0020] Some embodiments include an increment module that is
configured to estimate multiple increment values between the
dynamic input signal value and a current color management
value.
[0021] Some embodiments include a backlit display device configured
to utilize the lighting panel systems described herein.
[0022] Some embodiments of the present invention include methods of
providing a stabilized color management system in a solid state
lighting panel. Some embodiments of such methods may include
receiving, in a microcontroller, a color management signal
corresponding to a color characteristic of the solid state lighting
panel, analyzing the color management signal relative to a current
color management value that corresponds to a current color
characteristic, and setting a control system mode responsive to
analyzing the color management signal.
[0023] In some embodiments, receiving the color management signal
includes receiving a color management reference value corresponding
to a color characteristic of the solid state lighting panel. In
some embodiments, the color management reference signal includes a
user input signal.
[0024] In some embodiments, analyzing the color management signal
includes comparing a color management reference value to the
current color management value to determine a color management
change value and comparing the color management change value to a
threshold value. In some embodiments, setting the control system
mode includes setting the microcontroller to an open loop control
system mode if the color management change value is less than the
threshold value.
[0025] In some embodiments, if the color management change value is
greater than the threshold value, setting the control system mode
further includes setting the microcontroller to a closed loop
control system mode and calculating a plurality of color management
change increment values configured to incrementally adjust the
color characteristic from the current color management color value
to the color management reference value. Some embodiments may
include receiving, if the microcontroller is in the closed loop
control mode, a color management feedback value from a solid state
lighting panel photo sensor.
[0026] Some embodiments may include dynamically adjusting the
threshold value responsive to the current color management value,
wherein if the current color management value is closer to a
minimum color management value than it is to a maximum color
management value then the threshold is set to a first threshold and
wherein if the current color management value is closer to a
maximum color management value than it is to a minimum color
management value then the threshold is set to a second threshold
that is higher than the first threshold.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate certain
embodiment(s) of the invention.
[0028] FIG. 1 is a block diagram illustrating a lighting panel
according to some embodiments of the invention.
[0029] FIG. 2 is a schematic diagram illustrating a lighting panel
bar according to some embodiments of the present invention.
[0030] FIG. 3 is a block diagram illustrating a lighting panel
system according to some embodiments of the present invention.
[0031] FIG. 4 is a flow diagram illustrating operations for
protecting display components from adverse operating conditions
according to some embodiments of the present invention.
[0032] FIG. 5 is a flow diagram illustrating operations for
controlling a solid state lighting panel according to some
embodiments of the present invention.
[0033] FIG. 6 is a block diagram illustrating a lighting panel
system according to some embodiments of the present invention.
[0034] FIG. 7 is a flow diagram illustrating operations for
controlling a solid state lighting panel according to some
embodiments of the present invention.
[0035] FIG. 8 is a flow diagram illustrating operations for
controlling a solid state lighting panel according to further
embodiments of the present invention.
[0036] FIG. 9 is a flow diagram illustrating operations for
controlling a solid state lighting panel according to yet further
embodiments of the present invention.
[0037] FIG. 10 is a flow diagram illustrating operations for
controlling a solid state lighting panel according to some
embodiments of the present invention.
[0038] FIG. 11 is a flow diagram illustrating operations for
providing a stabilized color management system in a solid state
lighting panel according to some embodiments of the present
invention.
[0039] FIG. 12 is a block diagram illustrating backlit display
device according to some embodiments of the present invention.
[0040] FIG. 13 is a block diagram illustrating systems/methods for
controlling a solid state backlighting panel in backlit display
device according to some embodiments of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0041] Embodiments of the present invention now will be described
more fully hereinafter with reference to the accompanying drawings,
in which embodiments of the invention are shown. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein. Rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. Like numbers refer to like
elements throughout.
[0042] It will be understood that, although the terms first,
second, etc. may be used herein to describe various elements, these
elements should not be limited by these terms. These terms are only
used to distinguish one element from another. For example, a first
element could be termed a second element, and, similarly, a second
element could be termed a first element, without departing from the
scope of the present invention. As used herein, the term "and/or"
includes any and all combinations of one or more of the associated
listed items.
[0043] It will be understood that when an element such as a layer,
region or substrate is referred to as being "on" or extending
"onto" another element, it can be directly on or extend directly
onto the other element or intervening elements may also be present.
In contrast, when an element is referred to as being "directly on"
or extending "directly onto" another element, there are no
intervening elements present. It will also be understood that when
an element is referred to as being "connected" or "coupled" to
another element, it can be directly connected or coupled to the
other element or intervening elements may be present. In contrast,
when an element is referred to as being "directly connected" or
"directly coupled" to another element, there are no intervening
elements present. It will also be understood that when a first
element, operation, signal, and/or value is referred to as
"responsive to" another element, condition, signal and/or value,
the first element, condition, signal, and/or value can exist and/or
operate completely responsive to or partially responsive to the
other element, condition, signal, and/or value.
[0044] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" "comprising," "includes" and/or
"including" when used herein, specify the presence of stated
features, integers, steps, operations, elements, and/or components,
but do not preclude the presence or addition of one or more other
features, integers, steps, operations, elements, components, and/or
groups thereof.
[0045] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms used
herein should be interpreted as having a meaning that is consistent
with their meaning in the context of this specification and the
relevant art and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0046] The present invention is described below with reference to
flowchart illustrations and/or block diagrams of methods, systems
and computer program products according to embodiments of the
invention. It will be understood that some blocks of the flowchart
illustrations and/or block diagrams, and combinations of some
blocks in the flowchart illustrations and/or block diagrams, can be
implemented by computer program instructions. These computer
program instructions may be stored or implemented in a
microcontroller, microprocessor, digital signal processor (DSP),
field programmable gate array (FPGA), a state machine, programmable
logic controller (PLC) or other processing circuit, general purpose
computer, special purpose computer, or other programmable data
processing apparatus such as to produce a machine, such that the
instructions, which execute via the processor of the computer or
other programmable data processing apparatus, create means for
implementing the functions/acts specified in the flowchart and/or
block diagram block or blocks.
[0047] These computer program instructions may also be stored in a
computer readable memory that can direct a computer or other
programmable data processing apparatus to function in a particular
manner, such that the instructions stored in the computer readable
memory produce an article of manufacture including instruction
means which implement the function/act specified in the flowchart
and/or block diagram block or blocks.
[0048] The computer program instructions may also be loaded onto a
computer or other programmable data processing apparatus to cause a
series of operational steps to be performed on the computer or
other programmable apparatus to produce a computer implemented
process such that the instructions which execute on the computer or
other programmable apparatus provide steps for implementing the
functions/acts specified in the flowchart and/or block diagram
block or blocks. It is to be understood that the functions/acts
noted in the blocks may occur out of the order noted in the
operational illustrations. For example, two blocks shown in
succession may in fact be executed substantially concurrently or
the blocks may sometimes be executed in the reverse order,
depending upon the functionality/acts involved. Although some of
the diagrams include arrows on communication paths to show a
primary direction of communication, it is to be understood that
communication may occur in the opposite direction to the depicted
arrows.
[0049] Some embodiments of the invention may arise from the
recognition that a closed loop control system in a solid state
backlight is complex based on the need for accuracy, uniformity,
and/or responsiveness, that the effect of noise in a color
characteristic sensor may produce unwanted fluctuations, and that
filtering the sensor output may result in unwanted static
oscillation around a color characteristic setpoint. Accordingly,
some embodiments establish a light panel system that can set either
an open loop control mode or a closed loop control mode responsive
to control system demands. In this manner, unwanted control system
oscillation may be reduced.
[0050] Some embodiments of the invention may be directed to
flat-panel display applications. In flat-panel display
applications, it may be desirable to achieve high color gamut with
high efficiency. Increased gamut may allow the display to render a
wider range of perceivable colors. In some embodiments, this may be
achieved via multiple solid-state emitters or phosphors that may
emit different dominant wavelengths such as, for example, red,
green, blue, cyan and/or yellow, among others.
[0051] Reference is made to FIG. 1, which is a block diagram
illustrating a lighting panel according to some embodiments of the
invention. A lighting panel 10 may include multiple lighting panel
bars 20 each having multiple tiles 30 that include solid state
emitters. The solid state emitters may be serially arranged in, for
example, strings. Each of the lighting panel bars 20 may include an
interface 40 configured to provide electrical interconnection with
a control system. Although presented in the context of a lighting
panel 10 that includes multiple lighting panel bars 20, some
embodiments of lighting panels 10 described herein be configured
without multiple lighting panel bars 20 and/or multiple tiles 30.
For example, in some embodiments, lighting panel may be configured
to include a unitary structure that includes multiple solid state
emitters.
[0052] Reference is now made to FIG. 2, which is a schematic
diagram illustrating a lighting panel bar 20 according to some
embodiments of the present invention. In some embodiments, a
lighting panel bar 20 can include multiple strings 44A-C that can
each include multiple solid state lighting devices 42A-C. Each
string 44 may be configured to be substantially the same or each
one can differ in one or more ways. In some embodiments, each
string 44A-C includes solid state lighting devices 42A-C that emit
light in a different dominant wavelength. For example, solid state
lighting devices 42A can be configured to emit light having a
dominant wavelength generally corresponding to the color red.
Similarly, solid state lighting devices 42B and 42C can be
configured to emit light having dominant wavelengths corresponding
to the colors green and blue, respectively.
[0053] A lighting panel bar 20 of some embodiments may include one
or more strings 44 having solid state lighting devices 42 of
different colors. For example a lighting panel bar 20 can include a
least one string 44 having red solid state lighting devices, a
least one string 44 having green solid state lighting devices, and
a least one string 44 having blue solid state lighting devices. In
this manner, by selectively controlling the amount and/or duty
cycle of current supplied to each string, the chromaticity and/or
luminosity of the light emitted by the panel lighting bar 20 can be
controlled. The strings 44A-C can be controlled independent of one
another or as a group corresponding to the panel lighting bar 20.
Although discussed with reference to solid state lighting devices
configured to emit light having different dominant wavelengths, the
systems and methods herein may also be utilized in systems using
solid state lighting devices configured to emit light in a single
dominant wavelength. Furthermore, systems, etc., may use solid
state LED's including phosphors that, when energized, emit light
having multiple wavelengths and/or that otherwise emit
broad-spectrum light, such as, for example, a phosphor coated blue
LED.
[0054] Reference is now made to FIG. 3, which is a block diagram
illustrating a lighting panel system according to some embodiments
of the present invention. A lighting panel 10 may be a solid state
backlighting panel that may include multiple solid state emitters
arranged in strings. In some embodiments, the lighting panel system
includes a color management unit 360 configured to receive sensor
input from color sensor 340C and generate color management
information to control the light output of the strings.
[0055] One common method for controlling the current driven through
the strings is a Pulse Width Modulation (PWM) scheme. Many PWM
schemes may pulse the solid state lamps alternately to a full
current "ON" state followed by a zero current noppn state. The
output of the string may be controlled by varying the duty cycle,
which is the percent of the cycle that the string is placed in an
"ON" state. In some embodiments, if the pulse frequency is high
enough, a change in duty cycle may vary the average current and the
apparent luminosity of the string and/or emitter being pulsed in an
approximately linear fashion. In some embodiments, the color
management information is provided to a microcontroller 330 that
uses the color management information and/or sensor inputs from
temperature and other sensors 340A-B to adjust PWM duty cycles for
the strings to cause the panel 10 to emit light having a desired
chromaticity and/or luminance setting.
[0056] In some embodiments, the microcontroller 330 may be
configured to accept user input 350, which may also be used to
adjust the PWM duty cycles of the strings. The PWM duty cycle
information may be used by the microcontroller 330 to switch on or
off current drivers 320, which may drive strings and/or groups of
solid state emitters in the lighting panel 10. In some embodiments,
the microcontroller 330 may receive a user input 350 regarding a
request for a change in a color characteristic of the lighting
panel 10. The microcontroller 330 may generate PWM information
responsive to the inputs received from user input 350, the color
management unit 360, a temp sensor J40A and/or other sensors 340B,
among others. A color characteristic may include, for example, a
request for a change in luminance setting, which may be indicative
of the total light emission of the lighting panel 10. In some
embodiments, a color characteristic may include request for a
change in the lighting panel chromaticity value and/or "white
point". The chromaticity value may be controlled by varying the
relative outputs of the different colored solid state emitters.
[0057] Reference is now made to FIG. 4, which is a flow diagram
illustrating operations for controlling a solid state lighting
panel according to some embodiments of the present invention.
Operations for controlling display components include receiving a
color management reference value (block 402). In some embodiments,
the color management reference value may be a user input signal
that corresponds to a color characteristic of the solid state
lighting panel. The user input signal may be received by a
controller and/or color management unit configured to control the
solid state lighting panel. In some embodiments, the controller may
be, for example, a microcontroller. In some embodiments, the
controller may be a functional and/or task specific processor such
as, for example, an application specific integrated circuit (ASIC).
Examples of color characteristics include, for example, luminosity
and/or chromaticity, among others.
[0058] Responsive to receipt of the color management reference
value, the controller may enter a closed loop control mode (block
406). The closed loop control mode provides for the use of feedback
signals from, for example, sensors, to govern a change from a
current color characteristic that corresponds to a current color
management value to a color characteristic target that corresponds
to the color management reference value. In this manner, a change
in the color characteristic is applied via the controller (block
410).
[0059] Whether the color management target is reached is determined
(block 412). If the color management target is not reached, then
changes in the controller output are applied (block 414). If the
color management target is reached, the controller may enter an
open loop control mode (block 416). The open mode control may not
receive feedback signals from sensors. In this manner, unwanted
oscillations in the output of the controller and thus the color
characteristic due to sensor noise and/or other minor perturbances
may be reduced. In some embodiments, the controller may
periodically enter a closed loop control mode to correct for small
and/or gradual deviations in color characteristics. For example,
color and/or luminance drift may be corrected on a periodic basis,
including, for example, a period of one or more seconds, minutes,
hours and/or days, among others. In some embodiments, the periodic
interval may be as long as years. In some embodiments, the interval
may be determined by a trigger such as, for example, a user input
signal, an external calibration system and/or a supervisory control
system, among others.
[0060] Reference is now made to FIG. 5, which is a flow diagram
illustrating operations for controlling a solid state lighting
panel according to some embodiments of the present invention.
Operations for controlling display components include receiving a
color management reference value (block 502). In some embodiments,
the color management reference value may be a user input signal
that corresponds to a color characteristic of the solid state
lighting panel. The user input signal may be received by a
controller and/or color management unit configured to control the
solid state lighting panel. In some embodiments, the controller may
be a functional and/or task specific processor such as, for
example, an application specific integrated circuit (ASIC).
Examples of color characteristics include, for example, luminosity
and/or chromaticity, among others.
[0061] Whether a color management change value is greater than a
threshold value is determined (block 504). The color management
change value may be determined by the difference, ratio and/or
other relation between the received color management reference
value and a current color management value that corresponds to a
current color characteristic of the solid state lighting panel. In
some embodiments, the threshold value may be predetermined as a
fixed value. In some other embodiments, the threshold value may
vary as a function of the current color management value relative
to, for example, a color management value minimum, maximum and/or
operating range. For example, if the current color management value
is near a minimum and/or at the low end of the operating range, the
threshold value may be lower than if the current color management
value is near a maximum and/or at the high end of the operating
range.
[0062] If the color management change value is greater than the
threshold value then incremental color management reference values
may be generated (block 506). In this manner, the requested change
corresponding to the color management change value may be performed
in smaller discrete increments and may include delays between each
incremental change. By performing a large change in color
management value incrementally, a closed loop control mode may slew
more consistently and thus reduce overshoot and/or oscillation. For
example, a user input may request a 30% change in luminance, which
may be effected through three discrete 10% changes in luminance.
After generating incremental color management reference values, the
controller may enter a closed loop control mode to perform the
requested change in color management value (block 508).
[0063] If the color management change value is not greater than the
threshold value then incremental reference values may not be
generated and the controller may enter a closed loop control mode
to perform the requested change in color management value (block
508). This may generally be the case for less significant changes
as reflected in a lower color management change value. The closed
loop control mode provides for the use of feedback signals from,
for example, sensors, to accomplish a change from a current color
characteristic of the solid state lighting panel that corresponds
to a current color management value to a color characteristic
target that corresponds to the color management reference value. In
this manner, a change in the color characteristic is applied via
the controller (block 510).
[0064] A determination as to whether the color management target is
reached may be made (block 512). If the color management target is
not reached, then changes in the controller output are further
applied (block 514). If the color management target is reached, the
controller may enter an open loop control mode (block 516). The
open loop control mode controller may not receive and/or utilize
feedback signals from sensors. In this manner, unwanted
oscillations in the output of the controller and thus the color
characteristic due to sensor noise and/or other minor perturbances
may be reduced. In some embodiments, the controller may
periodically enter a closed loop control mode to correct for small
and/or gradual deviations in color characteristics. For example,
color and/or luminance drift may be corrected on a periodic basis,
including, for example, one or more seconds, minutes, hours and/or
days, among others. In some embodiments, the periodic interval may
be as long as years. In some embodiments, the interval may be
determined by a trigger such as, for example, a user input signal,
an external calibration system and/or a supervisory control system,
among others.
[0065] Reference is now made to FIG. 6, which is a block diagram
illustrating a lighting panel system according to some embodiments
of the present invention. The lighting panel system 600 may include
a lighting panel 610 that includes multiple solid state lighting
devices. In some embodiments, the solid state lighting devices may
be configured in strings and/or clusters in a tile and/or bar
arrangement. The lighting panel system 600 may include a multimode
color management system 620 that is configured to selectively
operate in a closed loop control mode responsive to a dynamic input
signal value. In some embodiments, the multimode color management
system includes a color management unit that is configured to
receive sensor inputs from multiple lighting panel sensors. In some
embodiments, the color management unit is configured to generate
color management information for controlling the light output of
the multiple solid state lighting devices.
[0066] In some embodiments, the multimode color management system
620 includes a color management controller that is configured to
receive color management information from a color management unit.
The multimode color management system may be further configured to
receive the dynamic input signal value from user input. In some
embodiments, the dynamic input signal value corresponds to a color
characteristic of the lighting panel 610. A color characteristic of
the lighting panel 610 may include, for example, white point, color
temperature, luminosity and/or chromaticity, among others.
[0067] In some embodiments, the multimode color management system
620 includes a mode selection module that is configured estimate a
color management change value and compare the color management
change value to the threshold value. The color management change
value may be estimated as a difference between the dynamic input
signal value and a current color management value corresponding to
the current color characteristic of the lighting panel 610. A mode
selection module may be further configured to set a color
management controller to a closed loop control mode if the color
management change value is greater than the threshold value. In
some embodiments, the mode selection module may be configured to
set a color management controller to an open loop control mode if
the color management change value is less than the threshold
value.
[0068] Some embodiments may include an increment module that is
configured to estimate multiple increment values between the
dynamic input signal value and the current color management value.
By estimating multiple increment values, a large change may be
divided into smaller discrete changes, which may be more
effectively accomplished in a closed loop control mode.
[0069] Reference is now made to FIG. 7, which is a flow diagram
illustrating operations for controlling a solid state lighting
panel according to some embodiments of the present invention. In
some embodiments, operations include receiving a color management
reference value corresponding to a color characteristic of the
solid state lighting panel into a color management controller
(block 710). In some embodiments, the color management reference
value may be received via a user input. For example, a user may
adjust the color characteristic of the solid state lighting panel
such as luminosity and/or chromaticity, among others. Operations
may also include adjusting a control mode of the color management
controller responsive to receipt of the color management reference
value (block 720).
[0070] Referring now to FIG. 8, which is a flow diagram
illustrating operations for controlling a solid state lighting
panel according to further embodiments of those illustrated in FIG.
7, adjusting the control mode may include operating a color
management controller in a closed loop control mode responsive to
receipt of the color management reference value (block 820). In
some embodiments, the color management controller may be operated
in the closed loop control mode until the solid state lighting
panel reaches a color characteristic target value corresponding to
the color management reference value. In some embodiments,
adjusting the control mode may also include operating the color
management controller in an open loop control mode when the solid
state lighting panel reaches the color characteristic target value
(block 830).
[0071] Reference is now made to FIG. 9, which is a flow diagram
illustrating operations for controlling a solid state lighting
panel according to yet further embodiments of the present
invention. In some embodiments, operations include receiving a
color management reference value corresponding to a color
characteristic of the solid state lighting panel into a color
management controller (block 910). In some embodiments, the color
management reference value may be received via a user input. For
example, a user may adjust the color characteristic of the solid
state lighting panel such as luminosity and/or chromaticity, among
others. Operations may also include adjusting a control mode of the
color management controller responsive to receipt of the color
management reference value (block 920). For example, the color
management controller may be set to a closed loop control mode upon
receipt of a color management reference value.
[0072] Some embodiments include estimating a color management
change value as a difference between the color management reference
value and a current color management value that corresponds to a
current color characteristic of lighting panel (block 930). In this
manner, the amount of requested change in color characteristic may
be determined. If the color management change value is greater than
a threshold value, an incremental value between the color
management reference value and the current color management value
may be generated (block 940). By generating an incremental value,
the control system may accommodate a large change in the luminance
and/or color setpoint via multiple smaller discrete changes.
Additionally, in some embodiments, the smaller discrete changes may
include delays therebetween to further improve control system
stability. In this manner the control system may slew more
consistently, which may reduce overshoot and/or oscillations.
[0073] Reference is now made to FIG. 10, which is a flow diagram
illustrating operations for controlling a solid state lighting
panel according to some embodiments of the present invention. In
some embodiments, operations include receiving a color management
reference value that corresponds to a color characteristic of the
solid state lighting panel into a color management controller
(block 1010). In some embodiments, the color management reference
value may be received via a user input. For example, a user may
adjust the color characteristic of the solid state lighting panel
such as luminosity and/or chromaticity, among others. Operations
may also include adjusting a control mode of the color management
controller responsive to receipt of the color management reference
value (block 1020). For example, the color management controller
may be set to a closed loop control mode upon receipt of a color
management reference value.
[0074] Some embodiments include periodically operating the color
management controller in a closed loop control mode (block 1030).
For example, in the absence of a received color management
reference value, the color management controller may switch to a
closed loop control mode to connect color and/or luminance drift.
The period by which the color management controller may switch to a
closed loop control mode may be defined in terms of seconds,
minutes and/or hours or more. In some embodiments, the periodic
interval may be as long as years. In some embodiments, the interval
may be determined by a trigger such as, for example, a user input
signal, an external calibration system and/or a supervisory control
system, among others. In some embodiments, a supervisory control
system may include a control system configured to control a
facility, building, site, system and/or operation, among
others.
[0075] Reference is now made to FIG. 11, which is a flow diagram
illustrating operations for providing a stabilized color management
system in a solid state lighting panel according to some
embodiments of the present invention. In some embodiments,
operations include receiving, into a color management controller, a
color management signal corresponding to a color characteristic of
the solid state lighting panel (block 1110). In some embodiments,
receiving the color management signal may include receiving a color
management reference value corresponding to a color management
characteristic of the solid state lighting panel. Some embodiments
provide that the color management reference signal is received via
a user input.
[0076] Embodiments may also include analyzing the color management
signal relative to a current color management value that
corresponds to a current color characteristic of the solid state
lighting panel (block 1120). Embodiments may also include setting a
control system mode responsive to analyzing the color management
signal (block 1130).
[0077] In some embodiments, analyzing the color management signal
includes comparing a color management reference value to the
current color management value to determine a color management
change value. Analyzing the color management signal may also
include comparing the color management change value to a threshold
value. In some embodiments, setting a control system mode may
include setting the color management controller to an open loop
control system mode if the color management change value is less
than a threshold value.
[0078] In some embodiments, it if the color management change value
is greater than the threshold value, setting the control system
mode may include setting the color management controller to a
closed loop control system mode. In such embodiments, multiple
color management change increment values may also be calculated. In
some embodiments, if the color management controller is in the
closed loop control mode, a color management feedback value from a
solid state lighting panel photo sensor may be received. Color
management change increment values may be utilized to incrementally
adjust the color characteristic from the current color management
color value to the color management reference value. In this
manner, a color characteristic may be gradually adjusted with
reduced undesirable control system effects such as overshoot and/or
oscillation.
[0079] Some embodiments may further include dynamically adjusting
the threshold value responsive to the current color management
value. For example, if the current color management value is closer
to a minimum color management value than it is to a maximum color
management value then the threshold may be set to a lower threshold
value. In contrast, if the current color management value is closer
to a maximum color management value than it is to a minimum color
management value than the threshold may be set to a higher
threshold value. By dynamically adjusting the threshold value, a
control system may be more resistant to unwanted static oscillation
which may tend to occur more often and/or be more noticeable at low
luminance settings, for example.
[0080] Reference is now made to FIG. 12, which is a block diagram
illustrating backlit display device according to some embodiments
of the present invention. A display device 1200 may include an LCD
panel 1210, including a two-dimensional arrangement of liquid
crystal shutters, that is controlled by an LCD controller 1230. The
LCD controller 1230 may control the output image 1260 by varying
states of the LCD shutters corresponding to different pixels.
[0081] The LCD panel 1210 relies on light transmission to control
an output image 1260. In this manner, the display device 1200 may
also include a lighting panel 1220 configured to provide light to
be selectively transmitted through the shutters of the LCD panel
1210. A lighting panel 1220 may include multiple strings of solid
state lighting emitters that can be controlled to achieve a desired
chromaticity, saturation, and/or luminance. Varying the output of
the string may be accomplished, for example, by turning the string
on for a portion of a period, which may be controlled by a
backlight controller 1240. In some embodiments, oscillations of one
or more color characteristics the solid state backlight panel 1220
may be reduced by varying the control mode of the backlight
controller between open loop and closed loop as a function of
received color management value references signals. In this manner,
display device 1200 may exhibit a desirable level of accuracy,
uniformity, responsiveness with improved control system
stability.
[0082] Reference is now made to FIG. 13, which is a block diagram
illustrating systems/methods for controlling components in a
backlit display device by controlling a lighting panel according to
some embodiments of the present invention. An LCD panel 1310 is
controlled by a display controller 1330, which refreshes the pixels
and the LCD panel 1310 at a predetermined refresh rate. A lighting
panel 1320 may also be included for providing luminance through the
LCD panel 1310. The lighting panel 1320 may be controlled by a
backlight controller 1340 that can drive multiple strings of solid
state light emitters using a current driver 1360. The output of the
lighting panel 1320 may be controlled by turning the emitters on
for specific portions of a period. In some embodiments,
oscillations of one or more color characteristics the lighting
panel 1320 may be reduced by varying the control mode of the
backlight controller between open loop and closed loop as a
function of received color management value reference signals.
[0083] Although some embodiments are described in connection with
LCD backlights, embodiments of the invention may be used for other
purposes, such as, for example, general lighting. In the drawings
and specification, there have been disclosed typical embodiments of
the invention and, although specific terms are employed, they are
used in a generic and descriptive sense only and not for purposes
of limitation, the scope of the invention being set forth in the
following claims.
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