Note: Descriptions are shown in the official language in which they were submitted.
CA 02329305 2000-12-20
1. Introduction
This document describes the Intelligent LED Luminary system being designed by
Oellux.
~ First, the Luminary itself will be described.
~ Second, its integration into a communication network wit! be described.
~ Thirdly, a summary of the advantages of the invention will be given.
9.7 Field of the Invention: Roadway Lighting
The invention proposes to replace existing Roadway Lighting luminaries with
luminaries using LEDs
(Light Emitting Diodes) as a source of light.
~.2 First planned application: Tunnel Lighting
Because of current LED limfiations in terms of light emission intensity, the
immediate application of the
invention would be in an environment requiring lower, btrt well controlled,
intensities. The first such
appli,,;ation we propose to implement is for Tunnel. Lighting.
Existinc roadu:ay standards for tonne' lighting divide the length of the
tunnel into a number of regions
Each regio-. requires s l~ghti~~g intznsity tha: increases as it is nearer the
entrance!exit points (because
of the p~esence of high=,~ illumination from the sun), and decrezses towards
the middle of the funnel.
As ar: example, CorlSlj°r the standard requirements specified by the
IESNA (Illmrrinafion Enoin~srs
Socie'y o' Nc,r*~; America) document RP22-96. The following specifications are
typical for the inner
section of a tonne(
IIJumi~ation Level.'
Lumira~ce should be at least Scd/m2 in daytime, 2.5cd1m2 in night-time.
Illumina!in Un;.'ormity:
Ra~,~o of f.ver ag G l iJlinimum luminance should be less than 2.0, ratio of
Maximum / Minimum
luminance shou;d be less than 3.5.
Our LED Inteli:gent Lun-~in2ries can be used directly in these inner ser;ions
(interior Zone), and also in
co:.c=~ wi;h exis~ing standGrd luminaries as a hybrid system in the outer
sections.
7.3 Current State-of the-Art
The most common current technology for tunnel lighting uses HIO (High-
Intensity Discha~e) lamps,
pov~ered vrit! ~ hio'~-voltace (e.g. 300VAC to 400VAC). A typical system will
use one f 301~r lamp per
1.7~m per road lane in order to sa'.isfy the daytime specfications required in
the Interior Zone of a
tunnel.
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2. (ntel(igent LED Luminary Description
2.9 Physical System Descripfion .
The Intelligent LED Luminary is composed of the following parts:
~ An array of LEDs;
~ An optical system optimizing the LED fight output;
~ A heat-dissipation system to reduce LED temperature;
~ An Electronic Circuit driving the LEDs;
~ A sealed case enclosing the above system;
~ A Power Supply system (exiemai to the Luminary).
2.1.1 LED Array
The light source of the Luminary is an an-ay of individual LEDs, 2ssembled on
one or more printed
circuit beard sec'~ons, perpendicularly to their surface. The number and type
of LEDs per sec;ion can
vay, ac~rd;ng to the luminance level required.
A= an example, a typi~l sec'~ion can contain 780 LEDs, arranged in a
rectangular pattern of 26x3D
L~Cs. A typic2l Lumvary can con;ain one or more such LED sec'.ion.
c
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2.1.2. Lateral Diffusion Conf~'vl
Light distribution simulations show that it may be advantageous to spread
laterally the light output of the
Luminary, in order to ob;ain a better illuminance uniformity.
The following process can achieve this:
1. Install a number of LED an-ay printed circuit boards (2-1) in the Luminary,
in a single line forma-
tion;
2. Give a slight tilt anole (2-2) to the LEO arrays so that they point tow2rds
the sides of the Lumi-
nary.
As an example, a typical LED Luminary can contain 2 LED arrays, with a tits
angle of 8' in opposite
directions for each painted circuit board.
See Figure '~: Lateral diffusion Control
2.1.3 Heat-Dissipation System
LED light output oradual;y decreases with usage time. As an example, a typical
LED will see its tight
output deCre~SE by 25% after 160,000 hours. The rate of this degra;;ation
increases as the junction
te.~-:pe-G:ure o' the LED increases. A~ an example. a typical LED will see the
same degrada:ion in
.~O.OOG hours at 2~'C as in 710;060 hours at 60°C. tt is therefore
important to keen the junction
fe-nperature o' the LED as (OYJ 2s possible, in order to increase its life
expectancy.
ft is knourn th2t most of the heat generated by a LED (3-1 ) is dissipated
through its leads (3-2j. In our
LED Lumi~,~ry we propose to minimise the LED junction temperature by
maximizing the transfer of neat
through the LED leads. The following process achieves this:
1. Cut the LED leads as they stick out of the solder side of the printed
circuit boards to G certain
le~oth L (3-~).
2. Fill the spare betv~een the LED leads with a compound conductive (3-4) to
heat but not to
electrical current. This compound will cover the whole surtace of the LED
Array (3-11), on the
solder side of the printed circuit board. The thickness T {3-10) of this
compound will be slig!ntly
greater than L so tha! no LED lead extends to its limit.
Apply a me',,a!lic heat sink (3-5) in contact w;th the compound mass, to
dissipate the heat tr~ns-
ferr ed tram the LED leads through the compound. This heat sink can be
intEgrated to the body
of the Luminary casing (3-6).
See Figure!: Heat-Dissipation System
2.1.4 Electronic LED Driver System
The LEDs will be driven by an electronic driver system with the following
characteristics:
1. LEOs will be Grouped in Chains of equal numbers of LEDs connected in series
(4-t) Typical
design: C=78 Chains of L=10 LEDs each.
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2. All LEDs Chains will be driven by constant current sources (4-2), in order
to stabilize their
luminosity and to maximize their life expectancy, which degrades faster if the
LED current is too
high.
3. Each LEDs Chain driver will be under the control of a microprocessor (4-3),
which can turn it On
or Off.
4. The system will include a means (4-4) to monitor the current flovving
through the LEDs Chains,
in order to identify defective LEDs.
b. The system will include a means (4-5) to measure the luminosity of a
typical LED in lts array, in
order to regulate the Luminary output luminosity.
6. The system v~'ilf include a Lamp Status Indicator (4-6) visible from tt~e
outside, which will be
activGted by the microprocessor vrhen the Luminary requires servicing.
7. The system wi(I include a bi-directional communications interface (4-7),
through which the
Luminary can be linked through a network to a Host computer.
8. The system will have a means (4-8) to sef and record a unique network
address, so that the
Host computer can individually identify each Luminary.
See Figure ~~~: Eleclronic LED Driver System
2.1.5 Sealed Case
Ali the Lumi:,ar}, par;s QESc~ibed above are installed in a case (~-1), vJith
2 transparent face (5-3) in
front c' the LEG ~.~ray (,~-4;. T. enSu''E lonc-term reliability the case is
environmentally sealed, so that
dust ~~;; vcaa~ ca~~~c; penet-ate inside.
The cas= has a s'.ape s,.ich that when the Luminary is inst211ed in its normal
position (e g. on the ceiling
(b-2) c= a tunnel facinc Cosvnv~ards), its light emission axis (5-~ is lifted
by a cErtain 2naSe (5-5) from
the Verviv,Gl (5-~'to;.a~ds 'he incoming traf;ic (5-8). Light distribution,
simulations show that ;his allows
o:.irniz~;ion o' tr,e ill~mir.ance.
See Figure <<': Sealed Case
2.1.6 Power Supply System
The Lummar y v,~i!; be powered by a low-voltage source. As an example, a
t?~pical Luminary ca . be
po~,nere~ t:y 2~VDC v.~ith a current draw of 4 amperes.
Since the male powe~ source in a tunnel will typically be at 304-400VAC, z
step-dov~n adaptor will be
used to pov~er tt~e LED Luminaries. A single step~tfown adaptor unit can be
made to power a cluster of
LED Luminaries. The nurr5er o' Luminaries per cluster is chosen so that the
total current drawn by the
cluster is reasona''ie, allowing the use of normal power cables.
Possible step-down a~~ptors include:
~ A line2r power supply, consisting of a transformer, a rectifier bridge and a
filter capacitor:
~ A sw;tching power supply;
~ A sv;iich;no pcwe.r supply with Power Factor Correction.
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2.2 Infelligenf Features
The microprocessor-based design of the LED Luminary will allow the
implementation of the following
'intelligent' features:
2.2.1 Variable Dimming Capability
The output luminosity level of the Luminay wilt be adjustable by controlling
the number of LED Chains
turned On or O'f (through ONOff Control Outputs 4-9). In our typical design
containing 78 individual
LEDs Chains per printed circuit board, the luminosity wi(I therefore be
continuously adjustable with a
resolution of 100/78 = 1.28%.
This method of dimming has the following advantages:
1. Advantage over prnpartional contral of LED current.'
It maximizes the life expeCancy of the LEDs by always using them at their
nominal current, and
keeping them On for a smaller proportian of time. This is because 1-ED
degradation falls down
faster with respect to usage time than it does with respect to current
2. .advantage over pulse-width modulation of the LE'D current.
It eliminates power transients and PowEr Factor problems which could be caused
by performing
dimming over 2 la-ge number of Luminaries through pulse-width modulation of
the LED current.
2.2.2 Long-Term Luminosity Degradation Compensation
The nu,"be,~ c= L>=Ds rewire:; tc ~=aerate the specified luminosity of the
Luminary at the start of izs life-
cycle can be dete-min2d using the initia' LED specifications. It is known that
as the LEDs age, their
outa:ri luminos:y, wi~' grad,~a!ly ciecrEase, or equiva;ently more LEDs will
be repuired to achieve the
specified luminosity.
The LED Array of the Luminary is therefore designed with a number of extra
LEDs Chains su~cient to
mai:~;ain its specified iu,~~ir'esity up to the end of its life-cycle. These
extra LEDs Chains will grada;ally
b2 1lsEu by the mi~rop~ocessor as the Luminary ages.
2.2.3 Light Intensity Self-Regulation
It is knov,T that for s given current, the output luminosity of a LED is
dependent on the ambient
tempereturev LED lurr~inosy is sicnifrcant!y higher at lower temperatures. The
invention proposes to
sta~~ilize the ove-all Luminary luminosity under varying ambient temperatures,
by implementing a Light
Intensity Se;f-Regulation system.
In addition to the LED Array, this system will use one (or more) Monitor LED
(4-10) opto-coupled to a
lig>~~t intensity-mea5~r~no device (~-11). The purpose of this system is to
evaluate the typical luminosity
o' the Array LEDs at any given time.
Tae t~cnior LED;s) will be identical to the LEDs used in the Array, supplied
with the same constant
curren; (4- t 2j, kept a' the same temaerature as the Array LEDs, and turned
On and Off in such a way
~s to maintain the sa.rne long erm usage rate as the Array LEDs.
The system will prefer ably use more than one Monitor LED (all of them being
driven in parallel). for the
fcllow:ne reasons:
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1. ~To prevent failure of the Light intensity Monitor mechanism should one
Monitor LED fail. Al-
though the probability of one LED failing is non-negligible, the probability
of more than one fail-
ing becomes ex;,eedingly small. The Monitoring system can automatically adapt
if it detects an
abrupt luminosity transition caused by a Monitor LED failure,
2. To obtain a Monitor luminosity averaged over more LEDs, which will be more
representative of
the typical luminosity of the Array LEDs.
The light intensity-mEasuring device (4-11) coupled to the Monitor LEDs (4-10)
is read by the
microprocessor (4-3). 6y comparing the Monitor~intensity to a reference value,
the microprocessor can
estirna~e the LED luminosity variations at any given moment and compensate by
adjusting the number
of LEDs Chains fumed On, thereby regularizing the overall Luminary luminosity.
This will have the following advantages:
~ Better energy ef iciency.~
less energy will be required at lower temperatures to achieve the specified
luminosity;
~ Be'fer Luminary longevity:
fever LEDs will be used at cower temperatures, thereby minimizing their usage
time.
2.2.4 Automatic LED Usage Equalization
A' each singe in t!~e course of the Luminary life, a variable number of LEDs
Chains will be On or Off,
sccording to the CitTlr~.l'1~ level requested and the luminosity compensation
mechanism. The micro-
procESSCr v.~~!'~ keep count of the usage time of each of the LEDs Chain in
the LED Array, and store
these inoividual usage lime values in non-volatile memory {4-13).
V'~f7en selectinc which LEDs Chains to tum On at any given time, the
microprocessor will automatically
pr:or;tize the use o' LEDs Chains having the shortest usage time. This wi;l
ensure that all LEDs have an
ec,ual'zed usage t~rre, with no LED degrading faster than others, therefore
optimizing the to»g-term
luminesrty deg-a::ation a~.d stability of the Luminary.
2.2.5 Chain Status t~fonitoring
The cyst: rr c2n monitor on-demand the LEDs integrity by measuring whe'.her
any LEDs Chain is open-
circuited. A simple way to achieve this function is as fellows:
c. Tu~-~ Off all LEDs Chains.
2. <,t the common supply point of all LEDs Chains, install in series with the
supply line a test
op'.ocoup;er (4~) input LED.
3. Turn O-~ one LEDs Chain; if it functions normally, the current it draws
will turn On the test opto-
couple~. If one or more LED in the Chain is open-circuited, the Chain will
drav~ no current and
therefore the test optocoupler will remain Off. The test optocoupler output is
monitored by a mi-
crcprocesscr inp:Jt.
4. Successively turn On each of the LEDs Chains in the LEDs Array and monitor
them.
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5. Once the test is finishe>j, remove the Pest optocoupier fi orn the supply
fine and resume normal
operation.
2.2.6 Lamp Status Indicator
The Luminary is equipped with a Lamp Status Indicator (4-6), visible from the
outside of the case.
Under control of the microprocessor, this indicator will provide the following
information about the
current state of the Luminary:
Indicator StateStatus Description
O'f NorTnal Normal operation
Flashing No Communication The c.~mmuni~tion link wi,,h the
Host PC is lost l
On End of Life . The luminary can no longer provide
its specified 1
luminosity, due to LED failure
or oeoradation.
Table 9: Lamp Sfatus Indicator
2.2.7 Soft Turn-OnlTurn-Off
In oroer lo preve-~t pourer transie~lts when the tunnel lighting is fumed On
or Off, or when its dimming
level is c;,anaed, the microrrocessor in each Luwinary will automs;~cafly make
any luminosity tr-znsnon
g.adua! Tr'is i= ac'~ieved by turning L)=Ds Chain On or Off one by one, with a
slight time delay between
each Chain.
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3. Intelligent Luminary Network Description
3.9 Network System Description
An integral part of the Intelligent LED Luminary invention is the linking of a
number of Luminaries to 2
communication nework (4-14}, and their control by a Most computer through this
network. This
systems.-level aspect of the invention brings a number of further capabilities
and features.
Any communication netv~-urk allowing multidrop connection of a large number of
Luminaries to a Hosi
computer is suitable. As an example, the following protocols can be used: RS-
485, Ethemet, TCP/IP.
3.2 Communications Network Features
3.2.1 Individual Luminary Address
Each Luminary on the netv~~ork will be assigned an individual, unique address.
The system is designed
so tha; the Host computer keeps a record of the physical location of each
Luminary, referenced by its
network address.
The address of each Luminary is stored in non-volatile memory (4-93} within
its electronic circuit. The
Luminary is equipped v~ith an Address Setting Switch (4-8}, accessible from
the outside of the case. At
system installation, '.=,is switch i~ activated to signal to the Host PC that
the Luminary is requesting a
neiv,~ork aodress, which is then generated and assigned automatically to the
Luminary by the Host PC.
3.2.2 Global Intensity Control
The Host PC cap co-trol the overa'l, or Global, (r~teraity lave! of the
lighting area.
3.2.3 Intensity Control by Zone
SE~aUSE IL !'1a5 individual contol over each Luminary, the Host PC can vary
the Intensity Level for each
s~~ec'r~c zone e' the lighting area. For exa;nple, the inner zone of a tunnel
can be set to a lower intensity
t'r~an an o~'ter Zone.
The nurr,ber, size and location of the lighting zones can be easily and
arbitrarily modified throuch the
Host sc'~vare.
3.2,4 Time-of-Day Intensity Control
The Host PC c2n vary the Intensity level according to the time of day, andlor
the ambient luminosity.
This lave; can be o~tirri;zed o~ a zone-by-zone basis, with the level in each
zone varying according to
it. luminance needs: in order to maximize energy efficiency.
3.2.5 Gradual Intensity Transitions
VL~!'1E.'1 Ch2rlCl'tg from onE Intensity level to another, the Has', can
generate gradual Intensity transitions
in order to r:~aximize e~eroy efficiency.
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For example; when changing from Night to Day luminance levels, a discreta
control system would have
to select the Day level as soon as marring ambient light starts to grow.
instead, the Host PC can
perform a gradual camping between Night end Day levels, thereby delaying the
increased energy
consump~or~ o' the Day level and enhancing drivers' visual comfort.
3.2.6 System Status Monitoring
The Host PC will poll each Luminary on the network at regular Interval, to
obtain tts current status
information. This information can be tabulated and logged.
~ Alarms can be triggered if any potential failure or degradation is detected;
~ Maintenance reports can be generated, listing the location and
identification of each Luminary
requiring servicing.
3.2.7 Fail-Safe Features
1. To prevent the loss of tunnel illumination under any circumstance (short of
power failure), each
Luminary vrill automatically revert to its normal Intensity level whenever
contact with the Host PC is
lost for a time inte~va! longer than an adustable Communication Time-pu;
period.
2. In cCse of power failure, the system can facilitate the generation of
emergency lighting backed up
by UPS (Uninterrupfible Pov.~er Supply). The energy consumption can be reduced
to a minimum,
either by greatly dimming the Luminaries, or by dynamically alternating the
Luminaries in the On
state.
3.2.8 Vehicle Presence Detection
In orde- to reduce ene-gy consumrtion, the Host PC can detect the presence of
vehicles in the lighing
area (:h~~u~h s;e~ca~c Ve!scle Presence Dete:.tors), and dim the Intensity
level when no vehicle is
presew This ci~iminc cGn be fu~~J~er refined on a zone-by-zone basis as the
vehicle moves across the
li~hiir,' GrG2.
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CA 02329305 2000-12-20
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CA 02329305 2000-12-20
Brief description of the drawings.
Fig 1 shows the configuration of two LED arrays according to one of the
embodiments of the
invention.
Fig 2 show a side view of an LED array having a heat dispersing assembly
according to one of
the embodiments of the invention.
Fig 3 shows a diagram of the different pans of the invention according to one
of the
embodiments.
Fig 4 shows the invention mounted on a ceiling according to one of the
embodiments.
Paqe 11
