U.S. patent application number 12/718958 was filed with the patent office on 2010-07-08 for indirect lighting fixture with reflectors.
This patent application is currently assigned to ECOLIVEGREEN CORP.. Invention is credited to Leonard C. Bryan, Paul L. Culler, Alfred Tracy.
Application Number | 20100172127 12/718958 |
Document ID | / |
Family ID | 39541473 |
Filed Date | 2010-07-08 |
United States Patent
Application |
20100172127 |
Kind Code |
A1 |
Tracy; Alfred ; et
al. |
July 8, 2010 |
Indirect lighting fixture with reflectors
Abstract
A method and system for adjusting a light source that is capable
of displaying light of different colors receives inputs from
various sources and provides an output color selection signal. The
output color selection signal is applied to the light source to
adjust the intensity and color thereof.
Inventors: |
Tracy; Alfred; (Delray
Beach, FL) ; Bryan; Leonard C.; (Palm Beach Gardens,
FL) ; Culler; Paul L.; (Tequesta, FL) |
Correspondence
Address: |
Stone Creek LLC;Alan M Flum
2019 NE 179 Street P67
Ridgefield
WA
98642
US
|
Assignee: |
ECOLIVEGREEN CORP.
Margate
FL
|
Family ID: |
39541473 |
Appl. No.: |
12/718958 |
Filed: |
March 6, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11940895 |
Nov 15, 2007 |
|
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|
12718958 |
|
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|
60859170 |
Nov 15, 2006 |
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Current U.S.
Class: |
362/147 ;
362/235 |
Current CPC
Class: |
H05B 41/3925
20130101 |
Class at
Publication: |
362/147 ;
362/235 |
International
Class: |
F21S 8/00 20060101
F21S008/00; F21V 1/00 20060101 F21V001/00 |
Claims
1. An indirect light fixture, disposed to simulate a planar light
source, comprising: (a) a printed circuit board; (b) a reflective
material, affixed to said printed circuit board, forming a
substantially planar reflective surface; and (c) a plurality of
high intensity LED assemblies, each assembly including: (i) a LED,
disposed to emit light; (ii) a LED housing, attached to said
printed circuit board; and (iii) a reverse paraboloidic reflector,
secured in proximal relation from said LED assembly such that said
reverse paraboloidic reflector blocks direct light from said LED to
a viewer, at any angle; wherein resulting combination said planar
reflective surface and said reverse paraboloidic reflector
effectively distributes light emitted from said LED over a greater
surface area than without said combination.
2. The indirect light fixture of claim 1, further including
mounting wires adapted to secure said paraboloidic reflector in
proximal relation from said LED assembly.
3. The indirect light fixture of claim 1, wherein said reflective
material is a reflective foil.
4. The indirect light fixture of claim 1, wherein said LED
assemblies are attached to a ceiling tile.
5. The indirect light fixture of claim 4, wherein said LED
assemblies are arranged in a grid pattern.
6. The indirect light fixture of claim 4, wherein: said printed
circuit board is plurality of printed circuit boards, each formed
in the shape of a strip; said strip containing a plurality of said
LED assemblies; said plurality of strips mounted in rows.
7. An indirect light fixture, disposed to simulate a planar light
source, comprising: (a) a printed circuit board; (b) a reflective
material, affixed to said printed circuit board, forming a
substantially planar reflective surface; and (c) a plurality of
high intensity LED assemblies, each assembly including: (i) a LED,
disposed to emit light; (ii) a LED housing, attached to said
printed circuit board; and (iii) a reflector, with a shape, said
reflector shape selected from a group consisting of a cone, a
pyramid, or a multifaceted geometric shape that approximates a
cone, secured in proximal relation from said LED assembly such that
said reflector blocks direct light from said LED to a viewer, at
any angle; wherein resulting combination said planar reflective
surface and said reflector effectively distributes light emitted
from said LED over a greater surface area than without said
combination.
8. The indirect light fixture of claim 7, further including
mounting wires adapted to secure said reflector in proximal
relation from said LED assembly.
9. The indirect light fixture of claim 7, wherein said reflective
material is a reflective foil.
10. The indirect light fixture of claim 7, wherein said LED
assemblies are attached to a ceiling tile.
11. The indirect light fixture of claim 10, wherein said LED
assemblies are arranged in a grid pattern
12. The indirect light fixture of claim 10, wherein: said printed
circuit board is plurality of printed circuit boards, each formed
in the shape of a strip; said strip containing a plurality of said
LED assemblies; said plurality of strips mounted in rows.
13. An indirect light fixture, disposed to simulate a planar light
source, comprising: (a) a printed circuit board; (b) a reflective
material, affixed to said printed circuit board, forming a
substantially planar reflective surface; and (c) a plurality of
high intensity LED assemblies, each assembly including: (i) a LED,
disposed to emit light; (ii) a LED housing, attached to said
printed circuit board; and (iii) a convex reflector, secured in
proximal relation from said LED assembly such that said convex
reflector blocks direct light from said LED to a viewer, at any
angle; wherein resulting combination said planar reflective surface
and said convex reflector effectively distributes light emitted
from said LED over a greater surface area than without said
combination.
14. The indirect light fixture of claim 13, further including
mounting wires adapted to secure said convex reflector in proximal
relation from said LED assembly.
15. The indirect light fixture of claim 13, wherein said reflective
material is a reflective foil.
16. The indirect light fixture of claim 13, wherein said LED
assemblies are attached to a ceiling tile.
17. The indirect light fixture of claim 16, wherein said LED
assemblies are arranged in a grid pattern.
18. The indirect light fixture of claim 16, wherein: said printed
circuit board is plurality of printed circuit boards, each formed
in the shape of a strip; said strip containing a plurality of said
LED assemblies; said plurality of strips mounted in rows.
Description
[0001] This application is a continuation application of U.S.
patent application Ser. No. 11/940,895 filed on Nov. 15, 2007,
which claims benefit to U.S. Provisional Application No. 60/859,170
filed on Nov. 15, 2006. The entire contents of U.S. patent
application Ser. No. 11/940,895 are hereby incorporated by
reference.
TECHNICAL FIELD
[0002] This disclosure relates generally to the commercial lighting
art. More particularly, this invention relates to lighting systems
and circuitry which may be used to replace and/or augment existing
fluorescent lighting fixtures and the like, as well as circuits for
operating such fixtures.
BACKGROUND
[0003] Conventional fluorescent lighting fixtures have been used
for many years in drop ceilings and for other applications in
industrial, commercial and residential establishments. These
fixtures have been used because of energy efficiency and due to
their wide distribution of light from a planar source. That is,
fluorescent lamps are more efficient than incandescent lamps at
producing light at wave lengths that are useful to humans. They
operate to produce less heat for the same effective light output as
compared to incandescent lamps. Also, the fluorescent bulbs
themselves tend to last longer than incandescent lamps.
[0004] Conventional fluorescent lighting fixtures utilize a type of
gas discharge tube in which a pair of electrodes is disposed at the
respective ends of the discharge tube. The electrodes are sealed
along with mercury and inert gas, such as argon, at very low
pressure within the glass tube. The inside of the tube is coated
with a phosphor which produces visible light when excited with
ultraviolet radiation. The electrodes are typically formed as
filaments that are either preheated or rapidly heated during a
starting process in order to decrease the voltage required to
ionize the gas within the tube. The electrodes remain hot during
normal operation as a result of the gas discharge. Electric current
passing through the low pressure gases emits ultraviolet radiation.
The gas discharge radiation is converted by the phosphor coating to
visible light. That is, such discharge occurs by a bombardment of
ultraviolet photons, emitted by the mercury gas, which excite the
coating to thereby produce visible light.
[0005] When the lamp is off, the mercury gas mixture is
non-conductive. Therefore, when power is first applied, a
relatively high voltage is needed to initiate the gas discharge.
Once the discharge begins to occur, however, a much lower voltage
is needed to maintain operation of the light. In this regard, the
fluorescent lamp may be viewed as a negative resistance element.
For operating the fluorescent lamp in its various stages, a ballast
is typically employed. The ballast provides the high voltage
necessary to ionize the gas to start the lamp, then to control the
voltage and limit the current flow once the lamp begins to conduct
current.
[0006] One special-purpose type of fluorescent lamp is known as a
Cold Cathode Fluorescent Lamp ("CCFL"). While CCFL technology is
generally known, its application has been limited to date.
Specifically, CCFLs are often used as white-light sources to
backlight liquid crystal displays or as decorative elements in
interior design. As with conventional fluorescent lamps, CCFLs are
sealed glass tubes filled with inert gases. When a high voltage is
placed across the tube, the gases ionize to create ultraviolet
("UV") light. The UV light, in turn, excites an inner coating of
phosphor, creating visible light.
[0007] The gases within the CCFLs are first ionized to create
light. Ionization occurs when a voltage, approximately 1.2 to 1.5
times the nominal-rated operating voltage, is placed across the
lamp for a few hundreds of microseconds. Before ionization occurs,
the impedance across the lamp is highly resistive. Indeed, in a
typical application, it may appear to be capacitive. At the onset
of ionization, current begins to flow in the lamp, its impedance
drops rapidly into the hundreds of K-ohms range, and it appears
almost completely resistive.
[0008] To minimize lamp stress, the striking waveforms should be
symmetrical, linear or sinusoidal voltage ramps without spikes.
Because CCFL characteristics vary greatly with temperature, the
voltage required to strike a CCFL also varies with temperature, and
in many cases, the timing of the lamp strike is not highly
repeatable. It may vary .+-.50%, even under the same temperature
and biasing conditions.
[0009] Therefore, a need exists for more practical and efficient
lighting solutions at reduced power consumption. Also, it would be
desirable to provide a lighting solution that provides improved
lighting characteristics through varying a color spectra provided
by the lighting solution.
SUMMARY
[0010] The present disclosure relates to a method and system for
adjusting a light source located in an interior space where the
light source is of the type that is capable of displaying light of
different colors. A microprocessor or other logic circuit receives
inputs from various sources. For example, a brightness or
illumination sensor senses the ambient illumination of the interior
space and provides an illumination signal to the microprocessor. A
brightness adjustment input signal is also optionally provided to
the microprocessor. In addition, a color balance adjustment input
signal is provided to the microprocessor. These and optionally
other input signals are processed in order to develop an output
color selection signal. The output color selection signal is
applied to the light source to alter either the intensity or the
color of the light source or both. Thus, for example, when a lamp
of a first color and a lamp of a second color are used, the output
color selection signal may be employed to adjust the respective
first lamp color and the second lamp color to obtain a desired
illumination.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a diagram of a Cold Cathode Fluorescent Lamp
("CCFL") arrangement that is suitable for use in a conventional
fluorescent lighting fixture according to one aspect of the
disclosure.
[0012] FIG. 1A is a pre-power supply circuit schematic diagram
suitable for use in conjunction with the embodiment of FIG. 1.
[0013] FIG. 2 is a block diagram of a control circuit that may be
used in conjunction with arrangement shown in FIG. 1.
[0014] FIG. 3 is a partial electrical schematic of the block
diagram representation shown in FIG. 2 according to one embodiment
of the disclosure.
[0015] FIG. 3A is a flowchart illustrating a procedure that may be
used in conjunction with the circuitry shown in FIGS. 2 and 3 for
providing an output color selection signal.
[0016] FIG. 3B illustrates a further procedure that optionally may
be performed by the disclosed circuitry.
[0017] FIG. 4 is a diagram of a CCFL lighting fixture according to
another aspect of the disclosure.
[0018] FIG. 4A is a switching power supply circuit that may be used
in conjunction with the disclosure.
[0019] FIG. 5 is a block diagram representation of a control
circuit for operating the lighting fixture shown in FIG. 4.
[0020] FIG. 6 is a partial electrical schematic diagram of the
block diagram representation shown in FIG. 5.
[0021] FIG. 7 illustrates an LED lighting fixture according to
another embodiment of the disclosure.
[0022] FIG. 7A illustrates one of a plurality of LED lighting
assemblies that may be used in conjunction with the fixture shown
in FIG. 7.
[0023] FIG. 8 is a block diagram representation of an LED control
circuit that may be utilized in the embodiment shown in FIGS. 7 and
7A.
[0024] FIG. 9 is a power supplying circuit for the embodiments
shown in FIG. 7, FIG. 7A and FIG. 8.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0025] Generally, the present disclosure relates to lighting
systems and circuitry which provides an output from a light source
capable of displaying light of different colors. By way of example,
the disclosure may be used to replace and/or augment existing
fluorescent lighting fixtures and circuits for operating such
fixtures. In one aspect, the disclosure provides a Cold Cathode
Fluorescent Lamp ("CCFL") arrangement and a CCFL lighting fixture
that are suitable for replacing conventional "preheat" or "rapid
start" fluorescent lamps and lighting fixtures. In another aspect,
the disclosure provides an LED array and control circuit for such
an array that is suitable for replacement of a conventional
fluorescent lighting fixture.
[0026] FIG. 1 is a cross section view of a fluorescent tube
assembly 10 according to one embodiment of the present disclosure.
The tube assembly 10 includes a generally cylindrical outer tube 12
that houses pairs of electrode control circuit subassemblies 14, 16
disposed at each end of the outer tube 12. A plurality of spaced
Cold Cathode Fluorescent Lamp ("CCFL") tubes, such as CCFL tubes 18
and 20 shown in FIG. 1, are located within the outer tube 12. In a
preferred embodiment, the tube assembly 10 has two CCFL tubes 18
and 20, arranged in spaced relation to each other. One of the
electrode control circuit subassemblies 14 includes a dimming
adjustment control 22 and a color adjustment control 24. As
explained below, the CCFL tubes preferably emit light in different
frequency spectra resulting in the emission of different colors of
light according to the intended use of the assembly 10. The
intensity and color emitted are controlled by the adjustment
controls 22 and 24, respectfully. The opposite control subassembly
16 may be used to complete a circuit path with the fluorescent
tubes and the control subassembly 14.
[0027] In this regard, the color emitted by the CCFL tubes is
chosen and controlled according to an intended color effect. Those
skilled in the art will appreciate that the manner in which color
affects individuals varies from person to person. Color parameters
are often used to define the effect of the color of light projected
on a living area, which may include: (1) color value, which is the
emotional response an individual may have to a particular color,
color spectra or group of colors; and (2) color rendering, which is
the ability for accurate colors to be perceived by projected light
on an object using midday sunlight as a reference.
[0028] Typical existing standard fluorescent bulbs emit light that
causes flesh tones to appear ghastly. This has a negative
psychological effect on individuals living or working under such
light. The reason for this is that the spectrum of light emitted by
these fluorescent lamps is not the same as that of the sun or of a
candle flame, as in the case of warm incandescent lighting. Current
bulbs are sometimes designed to emit more natural sun light
spectra, but they are expensive, and not often used. Additionally,
one may not vary the color of these bulbs without replacing the
bulb entirely.
[0029] One objective of the present disclosure is to provide a
simple method and arrangement to vary the color emitted by a light
source in a range that varies between a maximum wavelength and a
minimum wavelength. Such variation may be performed via a manual
adjustment or by automated processes. In an embodiment, a
determination of the wavelengths of color at the extrema of the
adjustment range is also determined. In addition, a preferred
embodiment employs two or more colorized bulbs instead of a single
bulb that emits a particular color to enable "filling-in" of
spectral gaps emitted by each bulb individually. This allows for a
more even color spectrum, thus approaching that of natural sunlight
or candle light.
[0030] Color has been found to have an affect on psychological
health and productivity of individuals and other animals.
Personality traits that are exhibited as a result of perceived
Color Values may vary from sad to happy, confusion to intelligence,
and fear to confidence. For example, neutral colors tend to cause
relaxing feelings of peace and well being. Red tones generate a
warm cozy response. White colors create a mood of purity and
innocence. Green-blue hues create sophisticated and witty moods.
Cranberry stimulates an intellectual response. Strong primary
colors (rather than neutral colors, as described above) create a
playful environment. Since Color Rendering may be entirely altered
by projected light on an object, the color of light being emitted
by a source may also contribute as much as the actual color of the
objects in an environment to the perceived color of such
objects.
[0031] Research indicates that variation in natural light
experienced by an individual throughout the day alters the mood of
the individual, such as to overcome feelings of boredom and
depression. Varying lighting, whether from a natural or artificial
source, throughout a room accomplishes the same result. The current
disclosure provides variation of light color and intensity
throughout the day with the use of automated procedures, thereby
further providing variance in color and intensity throughout a
room. The present disclosure also provides easy adjustment of light
intensity and color to fit within an "Amenity Curve, "based upon a
pilot study by A. A. Kruithof, 1941. See McCloud, Kevin "Ken
McClouds Lighting Style", Simon and Shuster; "Home Color Book",
Melaine and John Ayes, Rockport Publishing; "Interior Lighting for
Designers", Gary Gordon, John Wiley and Sons; Professor John Flynn:
http://www.iesna.org/100/PDF/CenturySeries/JohnFlynn.pdf).
[0032] To match the light output of standard fluorescent tubes when
using very bright phosphors and 2.0 mm CCFL tubes, three CCFL tubes
are conventionally placed within the tube assembly 12. This number
may vary, and it is currently contemplated that two and five or
more CCFL tubes may be utilized, depending upon a specific design
and application.
[0033] Each of the electrode control circuit subassemblies 14, 16
is used to house a plurality of Standard Hot Cathode Fluorescent
tubes, each of which contains heaters across the two electrode
control assemblies 14 and 16 shown in FIG. 1 The heaters are
controlled by a ballast (not shown) as is known in the art, and
operate to shut off when the gas inside the tube is sufficiently
hot to ionize. When this occurs, the bulb acts like a short circuit
across the length of the tube. The ballast acts as a current
limiting device, permitting sufficient electrical power to the
short circuit required to maintain ionization of the bulb. The
embodiment depicted in FIG. 1 provides a replacement for a standard
Hot Cathode Fluorescent tube, thus no structural ballast changes
are required. In this regard, the electrode control subassemblies
depicted by numerals 14 and 16 illustrate a power supply circuit
that performs the function of emulating a ballast, as described in
greater detail below.
[0034] FIG. 1A is a pre-power supplying circuit diagram that may be
utilized with the arrangement shown in FIG. 1 The pre-power supply
circuit 30 detects which two of the standard four lines present in
a typical fluorescent bulb fixture is receiving power. The four
contacts on a fluorescent bulb connect to respective connectors J1
a-d. Two pairs of comparator circuits, U1a, b and U2 a, b, sense a
signal developed on the appropriate pair of contacts. The
comparators U1a, b and U2 a, b operate to turn on the appropriate
one of a plurality of transistors Q1 through Q4. In a preferred
embodiment, the transistors Q1 through Q4 are high voltage
N-channel Enhancement MOSFET transistors. The MOSFET transistors Q1
through Q4 are arranged in a back-to-back configuration in pairs.
This arrangement overcomes the parasitic diode present in MOSFETS,
allowing the transistors to appropriately switch to provide an
alternating current output. The output is then rectified by a
plurality of diodes D1-D7 and passed to the 5 volt power supply
that supplies power to the CCFL driver circuit. In one embodiment,
the values and ratings of the components illustrated in FIG. 1A are
as shown in Table I below:
TABLE-US-00001 TABLE I Reference Item Qty Description Designator
Value 1 4 Resistor R1-R4 100K 1/10 w; 0402 2 4 Resistor R11-14 5.1M
1/8 w; 0805 3 4 Diode D18-21 1N4148 4 2 Diode D17, 22 1.22 V ref. 5
2 Op Amp V1-V2 TL082 6 4 FET Q1-Q4 N-MOSFET 300 V 7 6 Resistors
R5-R10 470K 8 8 Diodes D1-D8 DSS17-06CR 9 8 Diodes D9-D10
DSS17-06CR
[0035] FIG. 2 is a block diagram representation for a control
circuit 50 that may be used to power the tube assembly 10 (or
multiple tube assemblies) such as shown in FIG. 1. The control
circuit includes a microprocessor 52 that receives an ambient light
sensing signal from an ambient light sensor 54 via a line 56. The
microprocessor 52 operates in a logical fashion to provide an
output signal to lamp driver circuitry 58 via a line 60. The lamp
driver circuitry 58 also receives power from a power supply 62. The
lamp driver circuitry 58 is further disposed to receive other
signals, such as a color adjust signal on a line 64 and a
brightness adjust signal on a line 66. In response to these
signals, including the control signal supplied on line 60, the lamp
driver circuitry 58 provides a controlled output voltage and
current to the electrodes of a plurality of tube assemblies 10,
110.
[0036] FIG. 3 illustrates the control circuitry shown in FIG. 2 in
greater detail. In a preferred embodiment, the microprocessor 52 is
connected to a micro controller-based drive circuit, denoted as U1,
through a serial interface, denoted by lines 60a, 60b. In a
preferred embodiment, the microcontroller-based drive circuit U1 is
implemented as a 4-Channel Cold-Cathode Fluorescent Lamp Controller
manufactured by Dallas Semiconductor. In a preferred embodiment, a
brightness control circuit 54 illustrated in FIG. 3 varies a pulse
width output signal generated by the microcontroller 52, which is
passed through the driver circuit U1 and applied to the gate
terminal of a plurality of FETs, Q1-Q4.Q2. This output signal
controls the run voltage that is applied across the fluorescent
lamps CCFL1, CCFL2.
[0037] In one preferred embodiment, the brightness may be varied
from about 10% to 100%. Additionally, the microcontroller-based
drive circuit U1 that connects externally to the microprocessor 52
is operable to control the brightness based upon a signal intensity
signal received by the ambient light sensor 54.
[0038] The pulse-width varied output signal applied to Q1-Q4 Q2,
which varies the brightness of the fluorescent lamps CCFL1, CCFL2.
The brightness, however, may also or in addition be varied by means
of an algorithm operating within the microprocessor 52, as
described in greater detail below.
[0039] The power developed and used for striking and operating
lamps CCFL, CCFL2, is controlled by the microcontroller-based drive
circuit U1. The microcontroller-based drive circuit U1 is chosen to
automatically supply a desirable start (or pre-heat) and operating
power for the CCFL bulbs chosen. The components utilized in
conjunction with one preferred implementation of the disclosure are
provided in Table II below. By adjusting the component values in
Table II, the design may be modified to function correctly with
various diameter and length CCFL bulbs. Typical CCFL striking
voltages vary from 400 to 1000 volts, with run voltages nearly
one-half to one-fourth of their respective initial striking values.
The values and ratings for various components used in a preferred
embodiment of a control circuit as shown in FIG. 3 are set forth in
the following Table II.
TABLE-US-00002 TABLE II Bill of Materials for CCFL Fluorescent Bulb
Replacement For FIG. 3 Component Description Value U1 IC CCFL
Driver DS3984 CCFL1 CCFL Tube 2 mm .times. 24 CCFL2 CCFL Tube 2 mm
.times. 24 R1 Resistor 25K R2 Resistor 32K R3 Resistor 100 R4
Resistor 40K R5 Resistor 10K R6 Resistor 100 R7 Resistor 50K R8
Resistor 100 R9 Resistor 15K R0 Resistor 100 C1 Capacitor 10p C2
Capacitor 27n C3 Capacitor 0.1u C4 Capacitor 33u C5 Capacitor 10p
C6 Capacitor 27n C7 Capacitor 33u C8 Capacitor 100n C9 Capacitor
100n Q1-Q2 N Channel Dual Mosfet D19945T 1:120 L1-L2 Transformer
primary Primary CT
[0040] The color adjustment provided by resistors R8 (and R11 in
another embodiment below) vary the balance between pairs of CCFL
bulbs. Since each bulb in a pair (such as CCFL-1 and CCFL-2 in
FIGS. 2 and 3) is a different color, the color of the resulting
light emitted by the composite lamp may be varied anywhere from 10%
color1+100% color2 to 100% color1+10% color2 (i.e., from 10%
colorCCFL-1+100% colorCCFL-2 to 100% colorCCFL-1+10% colorCCFL-2).
For example, if color1 is white and color2 is yellow, a soft white
hue may be obtained in the middle of the color adjustment range.
The color adjustment in this case is achieved by varying the duty
cycle of pulse-width modulated output signals applied to the lamps
CCFL-1 and CCFL-2 shown in FIGS. 2 and 3. Various colors may be
used to benefit mood, ambiance, productivity, and even
psychological health in an environment, as described above.
[0041] FIG. 3A illustrates a procedure that may be performed by the
microprocessor 52 for the lighting system according to the
illustrated embodiment. The system begins and proceeds to a "Read
Ambient Light Signal" block in which the signal developed by the
ambient light sensor 54 shown in FIGS. 2 and 3 is read by the
processor 52. In a preferred embodiment, the ambient light signal
is read in synchronization with "anti-burst" portion of the output
cycle of the lamp, as explained below. In this way, the ambient
light is detected when the least contribution thereto is provided
by the lamps CCFL-1 and CCFL-2. The processor 52 operates in a
logical fashion to adjust the output color selection signal
supplied to the lamp driver circuit 58, which in turn, causes the
output pulse-width modulated signals applied to the lamps to be
altered. Specifically, to increase the intensity of the lamp
assembly, the intensities of the individual lamps CCFL-1 and CCFL-2
the duty cycle of their pulse-width driving signals changed
proportionally as the frequency of these driving signals is
substantially constant in a preferred embodiment. Thus, when the
detected ambient light exceeds an ambient light limit (preferably a
lumens high threshold), then the output color selection signal
provided to the lamp driver circuit 58 causes the pulse-width
output signals to both lamps CCFL-1 and CCFL-2 to be decreased in
proportion to each other. On the other hand, when the detected
ambient light is less than the threshold, the output signal
provided to the lamp driver circuit 58 causes the duty cycle of
pulse width signals applied to the lamps CCFL-1 and CCFL-2 to be
increased in proportion to each other as shown at a "Process
Ambient Light Signal" block in FIG. 3A.
[0042] Next, the system proceeds to a "Read Brightness Adjust
Signal" block and obtains data corresponding to the brightness
adjust signal supplied from the lamp driver circuit 58. The system
then proceeds to a "Process Brightness Adjust Signal" and causes
the pulse width output signals applied to the lamps CCFL-1 and
CCFL-2 to match the desired output intensity level. The system next
obtains a color balance adjust signal at a "Read Color Balance
Adjust Signal" block and processes this signal at a next block. In
this instance, the color balance adjust signal is also obtained
from the lamp driver circuit 58. For adjusting the color output of
the lamps, the respective intensities of the lamps CCFL-1 and
CCFL-2 are varied such that hey are reset to a different proportion
with respect to each other. The resulting output of the lamp
assembly, however, has the same brightness or intensity when the
summation of the intensities is the same as prior to the color
adjustment.
[0043] Next, a preferred implementation of the system proceeds to a
"Time of Day Algorithm Set" decision block. If the system is not
equipped with such functionality or if it is disabled, the system
returns to the beginning and repeats. On the other hand, if the
system has the capability to apply color variation signal based on
time-of-day, the system then branches to such procedures.
[0044] FIG. 3B illustrates an exemplary algorithm that may be
performed to automatically adjust the color and/or intensity output
of the fixture. At this point, the system sets the pulse width
output of a first color lamp (CCFL-1 in FIGS. 2 and 3) and a second
color lamp (CCFL-2 in FIGS. 2 and 3) according to the time of day
algorithm. As shown, the processor 52 begins by reading the Time of
Day in a first stage and then proceeds to a next stage in which a
Desired Adjust Rate, namely the desired rate at which the hue or
color temperature is to be automatically adjusted by the system, is
also read by the processor 52. In a preferred embodiment, the
Desired Adjust Rate may be either linear or a "reverse logarithmic
rate" in which the hue changes at an increased rate at the
beginning of a time period and at a reduced rate at the ending of
the period. In the illustrated embodiment, the processor 52
determines whether the Time of Day is the morning in a next
decision stage. If so, the processor 52 operates to cause the color
temperature to be increased according to the Desired Adjust Rate at
a next processing stage. That is, the color temperature or hue of
the combined output of the color lamps gradually increases during
the morning hours, such as between 7:00 am and 12:00 pm. Such
increase may occur either as a linear function or at a reverse
logarithmic rate such that the rate of change increases later in
the morning.
[0045] On the other hand, if the processor 52 determines that the
time of day is "Afternoon," the processor 52 operates to cause the
color temperature to decrease according to the Desired Adjust Rate,
as shown at a "Decrease Color Temp. According To Adjust Rate"
stage. During the afternoon, the hue or color temperature gradually
decreases, either in a linear fashion or at a reverse logarithmic
rate. The color temperature preferably remains constant during
evening hours, such as between 5:00 pm and 7:00 pm., as shown by
the "Maintain Constant Color Temp." stage in FIG. 3B.
[0046] Optionally, the embodiment shown in FIGS. 2 and 3 may also
include logic enabling the receipt of remote command signals. Such
signals may be received from remote sources via a local area
network or a wide area network. In this way, the control
arrangement may receive external control signals via a home network
or via the Internet. Such control signals are received by the
processor 52 and processed in order to vary the output color
selection signal. Specifically, the processor adjusts the
pulse-width output signal provided to the lamps CCFL-1 and CCFL-2
such that the summation of the color pulse-width of CCFL-1 and the
color pulse-width of CCFL-2 are altered to be the same as the
Adjusted pulse-width signal corresponding to the received remote
command signal.
[0047] Advantageously, the fluorescent replacement bulb assembly
includes adjustment for both brightness and color. This enables the
assembly to last up to five times longer provide greater efficiency
than conventional fluorescent bulbs because energy use can be
limited by automatically or manually dimming the lamp. The recent
need for global energy savings, and the fact that lighting consumes
30% of the world's energy makes this a very desirable ecological
product.
[0048] The brightness and/or color may be both automatically
controlled based upon ambient light needs. Specifically, when the
ambient light gets darker, more light is emitted by the tube
assembly. On the other hand, when ambient light gets brighter, less
light is emitted. The color may also be varied according to an
algorithm that operates as explained above. In a preferred
embodiment, the sensor 54 is a broad spectrum visible light sensor
that measures the ambient light. This sensor is also the currently
preferred sensor illustrated as sensor 154 in FIG. 5 and sensor 254
in FIG. 7 below. The ambient light is preferably measured during
short "anti-bursts" of generated light that occur periodically as a
result of sinusoidal nature of run power supplied to each lamp. In
a preferred embodiment, the light generated by the lamp assembly is
reduced to 10% of maximum during this relatively short burst of
time. This so-called "anti-burst" frequency and the length of the
burst itself are adjustable according to an algorithm that
determines an optimum detection versus potential undesirable
flicker. In a preferred embodiment, a five second period is used as
the "anti burst" interval and 330 microseconds is used for the
length of an "anti-burst."
[0049] The detected ambient light is averaged from several
"anti-burst" cycles, at which time the phosphor has dimmed to 10%
of its full brightness potential. In this way, the ambient is
measured during the zero crossings of the sine wave, for several
successive cycles, near the end of the "anti-burst." In the
illustrated embodiment, light measurement for three consecutive
zero crossings are averaged at 15 micro-second intervals. The
ambient sensor 54 is also oriented away from the lamp so that it
senses light from the ambient as much as possible. This avoids
effects of residual light glowing in the phosphors of the local
lamp.
[0050] Color variations, such as for example, from white to soft or
yellow-white vary according to the time of day. The softer white is
actually a mixture of green and blue light which occurs outside
mostly during the morning and evening hours. The algorithm is thus
basically a variation in color and brightness with respect to time,
by varying the intensity of the light pairs as described above. Any
variation may be accomplished, but the current embodiment varies
the light gradually from 10% color1+100% color2 to 100% color1+10%
color2 over a desired time interval, such as in a 12 hour period or
according to the Time of Day procedure described above. The softer
light containing more blue-green is applied in the earlier and
later hours of each day. The whiter light is applied during noon
and midnight times of the day. The addition of a FET in series with
R8 (and one in series with R11 in the other embodiment) gated by
the output of a DAC which is connected to the micro controller is
required to add this functionality. Additionally, the maximum
brightness level can be set limited manually with a screw driver
(from 10% to 100% with the screw driver adjustment).
[0051] The color adjustment feature provides increased versatility
as multiple bulbs of different colors are not required for
different applications. Additionally, a warm color light may
readily be provided to an interior space, such as inside a
building. The disclosed arrangement also provides extended wear
inasmuch as it preferably employs CCFL technology instead of
standard fluorescent technology. The driver is more sophisticated
to power several CCFL bulbs as compared with standard fluorescent
bulbs, but no internal filament is used that can burn out, thus the
life span is increased. Other ballast changes or other modification
is not required for this fluorescent replacement bulb to function.
It may be inserted into an existing fixture and used.
[0052] In an alternative embodiment, the lamp assembly is equipped
with remote control features to adjust brightness and/or color of
all the lamps within a room, but the only allowable variance will
be within the limits set by the screwdriver settings. This
embodiment also requires an appropriate ballast change to the
existing fluorescent fixture. Other embodiments will adjust light
intensity and/or color automatically based upon time of day in
combination with ambient light. Specifically, this assembly may
work as described above.
[0053] Another aspect of the disclosure addresses the drawbacks for
current drop ceiling fluorescent lighting systems. The current
systems are large and heavy requiring large effort in installation
and inspections. On the other hand, the present disclosure further
provides a relatively lightweight solution that drops into the drop
ceiling just as a ceiling tile. This is accomplished by using
standard Cold Cathode Fluorescent tubes. This technology is as
energy efficient as T8 fluorescent technology, but can be set for
even higher efficiency with built-in dimming, which is not easily
possible with current fluorescent systems. There is also a slight
gain in efficiency due to the use of small diameter CCFL tubes,
when compared with typical hot filament T8 or T12 larger diameter
fluorescent bulbs. The highest efficiency fluorescent tube has a
diameter in the 1-2 mm range. Additionally, concerns with respect
to the human health effects from exposure to current fluorescent
lamps due to the spectrum and color of the light (in that bright
white light is very artificial) are avoided in this disclosed
arrangement. The disclosure according to another aspect resolves
that problem with a built-in color correction adjustment.
[0054] FIG. 4 is an isometric view of another embodiment of the
disclosure. In this embodiment, an integrated ceiling tile assembly
120 is adapted to be fit within a conventional ceiling tile system.
The tile assembly 120 has a generally rectangular configuration
that includes a housing portion 122 and a plurality of CCFL tube
assemblies 124-130, which may be generally of the construction
shown in FIG. 1 in certain respects.
[0055] This embodiment provides a lighting system that consists of
a standard drop ceiling tile lamp. This lamp does not require big
bulky fixture with a ballast as in current drop ceiling systems. In
one exemplary embodiment, the tile assembly is the size of a
2'.times.2' ceiling tile, and no larger. The lamp bulbs 124-130 may
last up to five times as long as standard fluorescent bulbs. Also,
this embodiment does not require a licensed contractor or other
skilled personnel for installation because the voltages used to
power the lamps are low enough to be safe for layman installation.
A ceiling tile is removed and simply replaced with the light weight
lamp tile. One wire must be attached to the low voltage
distribution system mounted above the drop ceiling. A licensed
electrician is required to mount the low voltage supply only.
[0056] This feature addresses the problem conductor length used to
drive the CCFL tubes within the lamp, and the difficulty related to
attaching the conductor to the driving power. That is, the
invention uses a low impedance flat conductor having a
point-of-need drivers and a low impedance quick connect connector
for the CCFL tubes. With this system, the entire drop ceiling lamp
assembly can be controlled by one main driver, distributed to a
sub-driver circuit located near each CCFL tube. The quick connect
connectors allow each tube to be easily replaced and held in place
by gravity and tension. CCFL technology offers longer life, about 3
times that of standard fluorescent tubes, because there is no
filament to burn-out. As a result, CCFL technology also offers
better resistance to the environmental effects of vibration, since
filaments tend to break under vibration stresses.
[0057] FIG. 4A is an electrical schematic diagram that depicts a
circuit used to generate a 5-volt DC output signal to supply the
various CCFL driver circuits that may be used with the present
disclosure. The circuit is a 5 Volt switching power supply that may
be designed by using any of a number of sources, such as an on-line
tool provided by National Semiconductor, WebBench.TM.. A signal Vin
is a source voltage depending upon the type of fixture (Fluorescent
Bulb Replacement, Ceiling Tile, or LED described below) being
utilized. An integrated circuit U1 is a switcher IC for a buck
converter. In this embodiment, a 5 Volt output signal is provided
at a line Vout. A pair of capacitors Cin and Cout are used as
filter capacitors that smooth the input and output voltage signals.
A resistive-capacitive network implemented with capacitors Cramp,
Ccomp, and resistors Rt, and Rcomp are used to soft start the
switcher and provide correct phase response. Resistors Rfb are used
to finely adjust the voltage to 5 volts. A diode D1 and inductor L1
are used to rectify and filter the high frequency pulses generated
by the switch in the controller U1. The input voltage signal Vin is
34 volts which is full-wave rectified from the main 24 volt AC bus
wiring used in the preferred embodiments of the disclosure (except
the Fluorescent Bulb Replacement version). The 24 volt AC input
allows for non-licensed electricians to install the ceiling tiles.
The Fluorescent bulb replacement version may also be installed in a
similar fashion to as how one would replace a T12 or T8 fluorescent
bulb.
[0058] Table III below sets forth the type and rating for the
components according to a preferred implementation of the circuit
shown in FIG. 4A
TABLE-US-00003 TABLE III Item Manufacturer Description Ref.
Designator Value Title 1 Yegeo America Capacitor Cramp Capacitance
330 pf Voltage-Rated 50 V Tolerance +/-10% 2 AVX Capacitor Cbyp
Capacitance 1 uF Voltage-Rated 25 V Tolerance +/-10% 3 AVX
Capacitor Cboot Capacitance 0.022 uf Voltage-Rated 50 V Tolerance
+/-10% 4 AVX Capacitor Css Capacitance 8200 pf Voltage-Rated 50 V
Tolerance +/-10% 5 Diodes Inc Diode D1 Voltage Rated 90 V Current
Rating 3 A 6 Kemet Capacitor Ccomp2 Capacitance 750 pf
Voltage-Rated 50 V Tolerance +/-10% 7 Coiltronics Inductor L1
Mounting SMD Inductance and 33UH 7.7 A Current 8 Panasonic Resistor
Rfb1 Resistance in 1k Ohms Power 1/10 W Tolerance 1.00% 9 Panasonic
Resistor Rt Resistance in 21k Ohms Power 1/10 W Tolerance 1.00% 10
Panasonic Resistor Rfb2 Resistance in 3.09k Ohms Power 1/10 W
Tolerance 1.00% 11 Panasonic Resistor Rcomp Resistance in 9.31k
Ohms Power 1/10 W Tolerance 1.00% 12 Murata Capacitor Cin
Capacitance 6800 pF Voltage-Rated 100 V Tolerance 10.00% 13 Murata
Capacitor Ccomp Capacitance 4300 pF Voltage-Rated 20 V Tolerance
5.00% 14 National Semi U1 2.5A INTEGRATED BUCK REG.75 V LM5005 15
Kemet Capacitor Cout Capacitance 47 uF Voltage-Rated 20 V Tolerance
+/-10%
[0059] The tile assembly 120 preferably is driven by circuitry, and
has many or all of the features for brightness and color manual and
automatic adjustments, as the tube assembly 10 described above.
Specifically, FIG. 5 illustrates a block diagram representation for
a control circuit 150 that may be used to power the plurality of
tube assemblies 124-130. As with the control circuit shown in FIGS.
2 and 3, the control circuit 150 includes a microcontroller 192
that receives an ambient light sensing signal from an ambient light
sensor 154 via a line 156. The microcontroller 192 operates in a
logical fashion to provide an output signal to lamp driver
circuitry 158 via a line 160, essentially in a manner similar to
that described above in connection with FIGS. 3A and 3B. The lamp
driver circuitry 158 also receives power from a power supply 162,
the details of which are described above in connection with FIG.
4A. As with the control circuit 50, the lamp driver circuitry 158
is further disposed to receive other signals, such as a color
adjust signal on a line 164 and a brightness adjust signal on a
line 166.
[0060] In response to these signals, including the control signal
supplied on line 160, the lamp driver circuitry 158 provides a
controlled output voltage and current to the electrodes of a
plurality of tube assemblies 124-130.
[0061] FIG. 6 illustrates the control circuitry 150 in greater
detail. That is, the control circuitry includes a micro controller
192 that is connected to lamp driver circuitry 158, which includes
a microcontroller-based drive circuit U1, as well as ambient light
sensor circuitry 154. The differences between the circuit used in
conjunction with the embodiments of FIG. 3 and FIG. 6, namely, the
fluorescent bulb replacement version versus the drop-ceiling tile
version, are minimal in one implementation of the disclosure. For
example, the embodiment shown in FIG. 3 uses a different number and
size of bulbs, and the associated values for components in Table 1,
which vary depending upon bulb type used in the design, are
likewise different. Another difference is in the physical placement
of the electronics. In the bulb replacement version, the
electronics are miniaturized as much as possible and mounted at one
or the other end of the bulb. In the drop ceiling version, the
electronics may be mounted anywhere above the foil reflective
material.
[0062] The values and ratings for various components used in a
preferred embodiment of the circuit illustrated in FIG. 6 are set
forth in the following Table IV below:
TABLE-US-00004 TABLE IV Component Description Value U1 IC CCFL
Driver DS3984 CCFL1 CCFL Tube 2 mm .times. 24 CCFL2 CCFL Tube 2 mm
.times. 24 CCFL3 CCFL Tube 2 mm .times. 24 CCFL4 CCFL Tube 2 mm
.times. 24 R1 Resistor 25K R2 Resistor 32K R3 Resistor 100 R4
Resistor 40K R5 Resistor 10K R6 Resistor 100 R7 Resistor 50K R8
Resistor 100 R9 Resistor 15K R0 Resistor 100 R11 Resistor 100 R12
Resistor 100 C1 Capacitor 10p C2 Capacitor 27n C3 Capacitor 0.1u C4
Capacitor 33u C5 Capacitor 10p C6 Capacitor 27n C7 Capacitor 33u C8
Capacitor 100n C9 Capacitor 100n C10 Capacitor 10p C11 Capacitor
27n C12 Capacitor 33u C13 Capacitor 10p C14 Capacitor 27n C15
Capacitor 33u C16 Capacitor 100n C17 Capacitor 100n Q1-Q4 N Channel
Dual Mosfet D19945T 1:120 L1-L4 Transformer primary CT
[0063] FIGS. 7 and 8 illustrate a further embodiment of the
disclosure according to another aspect. In this embodiment, a
plurality of high intensity white or multi-color light emitting
diode (LED) assemblies (such as the assembly 220 shown in FIG. 7A)
are attached to a ceiling tile 200. Preferably, the white or
multi-color LED assemblies 220 are arranged in a grid pattern. As
shown in FIG. 7A, the LED assembly 220 comprises an LED housing
222, mounted within a printed circuit board 224. In a preferred
embodiment, a reflective foil sheeting material 226 is attached to
one side of the printed circuit board 224. For dispersing the light
emitted by the color LED, a reverse paraboloidic reflector 228 is
disposed in proximal relation to the LED housing 222. In the
illustrated embodiment, the reflector 228 is secured in spaced
relation from the color LED assembly 222 with the use of mounting
wires such as lead wires 230 and 232. Those skilled in the art will
appreciate that other mounting means may be utilized.
[0064] FIG. 8 is a block diagram of a control circuit 250 for the
embodiment of the disclosure illustrated in FIGS. 7 and 7A. This
embodiment is used to drive high intensity white or multi-color
light emitting diode (LED) arrays, that are preferably arranged in
a ceiling tile as shown in FIG. 7. The control circuit 250 includes
a micro controller 252 that receives an ambient light sensing
signal from an ambient light sensor 254 via a line 256. The
microcontroller 252 operates in a logical fashion to provide an
output signal to lamp driver circuitry 258 via a line 260. The lamp
driver circuitry 258 also receives power from a power supply 262.
The LED driver circuitry 258 is further disposed to receive other
signals, such as a color adjust signal on a line 264 and a
brightness adjust signal on a line 266.
[0065] In response to these signals, including the control signal
supplied on line 260, the lamp driver circuitry 258 provides a
controlled output voltage and current to the electrodes of a
plurality of LED arrays 268, 270. Those skilled in the art will
appreciate that the microcontroller 252 operates according to the
procedures shown in FIGS. 3A and 3B above.
[0066] FIG. 9 is a power supplying circuit for the embodiment shown
in FIGS. 7-8. The LED ceiling tile version is preferably made of
power-supplying strips (denoted as Power LED Strip) that are
interconnected to a Switching Power Supply Driver Circuit via a
main 24 volt bus. The average current is sensed across each LED,
via an Average Current Sense Circuit in a conventional manner and
fed back to the Switching Power Supply Driver circuit. In a
preferred embodiment, a 24-volt supply is used to power the ceiling
tiles so that a licensed electrician is not required. An entire
drop ceiling lighting system can be installed by the ceiling
contractor.
[0067] Each LED is heatsunk and mounted on the PC board strip, each
containing the reverse paraboloidic reflector 228 shown in FIG. 7A.
The LEDs in the strip are connected in series to reduce energy
losses. To further improve efficiency, a current averaging circuit
sends a signal back to the switching power supply driver feedback,
ensuring the optimum power to the LED strip. Some LEDs in the strip
may be slightly brighter or dimmer than others, but the average
brightness for each strip in the tile should be at least
substantially the same.
[0068] This embodiment provides many advantages with respect to
known fluorescent lighting systems. Throughout the world
fluorescent fixtures have been used for many years in drop
ceilings. These fixtures have been used because of the energy
efficiency and the wide distribution of light from a planar source.
This embodiment addresses the drawbacks for current drop ceiling
fluorescent systems in that current systems are large and heavy.
This requires substantial effort in installation and inspection.
The disclosed embodiment, which employs a planar array of
high-intensity LEDs, is relatively light and drops into the drop
ceiling just as a ceiling tile. This technology provides light more
efficiently than T8 fluorescent technology, and can be set for even
higher efficiency with built-in dimming, which is not easily
possible with current fluorescent systems. There is also the
ecological advantage in that LEDs do not contain the mercury that
potentially contaminates the environment upon breakage of
fluorescent lamps. While LEDs may contain amounts of arsenic, but
this arsenic can only be released into the environment by finely
grinding the solid LEDs into powder, as opposed to the ease of
breaking a fluorescent bulb.
[0069] Additionally, there are concerns over the human health
effects using current fluorescent lamps due to the spectrum and
color of the light. The bright white light is very artificial in
nature causing stress. The present disclosure resolves that problem
with a built-in color correction adjustment. Additionally,
utilization of high frequency drivers in LED arrays and the
required conductor length necessary to drive the lamps, as well as
the difficulty related to attaching the conductor to the driving
power are avoided. In the disclosed embodiment, low impedance flat
conductors with point-of-need drivers may instead by utilized. The
entire drop ceiling lamp assembly can be controlled by one main
driver, distributed to a sub-driver circuit located near each strip
of LEDs.
[0070] The disclosed embodiment also addresses a safety concern
with use of high intensity LEDs due to the point source nature of
LEDs. The reverse parabolic reflector 228 disposed proximated to
each LED effectively distributes the emitted light over a greater
surface area via a foil reflector backing. As shown in FIG. 7, one
of a plurality of LEDs with paraboloidic reflector 228 to be
mounted as an array designed to replace a drop-ceiling tile. This
reflector design provides for an easy an inexpensive solution to a
drop ceiling tile replacement, as no lens is required below the
lights. Additionally, the reflector completely blocks direct light
to a viewer, at any angle, preventing potential eye damage from
looking directly into high intensity LEDs. While a paraboloidic
shape is the currently most preferred mode for practicing this
aspect of the invention, other shapes such as a pyramid, cone, or
multifaceted geometric shape that approximates a cone or the like
would also work. Further, circuit board size (and thus cost) is
reduced by making the boards into strips rather than as one solid
plane. The strips may be mounted as rows all in one direction
forming a planar array of LEDs. The resulting light source is
planar in nature.
[0071] Therefore, the invention provides an LED ceiling tile
assembly with all the features of the CCFL ceiling tile model,
described above. Additionally, the ceiling fixture has a unique
reflector design that makes the LED lamp easy and inexpensive to
assemble. Each LED mounted on the Printed Circuit board preferably
includes a reverse parabolic reflector or similar design mounted
above it. An array of LEDs will make up the ceiling tile. No
additional lens or reflection grid is required. Additionally, this
system of reflection serves two purposes. It scatters the light to
simulate a planar source and it completely blocks the direct light
from each LED, which could potentially damage a human eye because
of the great intensity of LEDs as a point source.
[0072] Accordingly, a lighting arrangement and control circuitry
meeting the aforestated objectives has been described. Those
skilled in the art should appreciate that the invention is not
intended to be limited to the above described currently preferred
embodiments of the invention. Various modifications will be
apparent, particularly upon consideration of the teachings provided
herein. That is, certain functionality that has been described in
conjunction with software components of the system may be combined
with other components, or alternatively, be implemented in numerous
other ways, whether by other software and/or hardware
implementations. Also, although the invention has been described in
the context of interactions of various computing systems in a
network configuration, those skilled in the art will recognize that
many other configurations may be employed. Thus, the invention
should be understood to extend to that subject matter as defined in
the following claims, and equivalents thereof.
* * * * *
References