CA2329305A1 - Lighting device - Google Patents

Abstract

The current invention is an intelligent lighting device capable of being connected to a network and being controlled by a host computer also connected to the network.

Description

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.

n~

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 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.
Paoe 3 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.

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:

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.

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.

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.

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.

~ ,?

~

N

O j C ~ U

v o t U ~ C

v . .

m ~ i C ' C = I
C .

E ~ ~ ' ~ o ~

0 v v> t LiJ c a t v ~ ~ ! ' I t ~' o o O' ~ ) ~ 'C I ~ I
. ~C

~ _ r. l0 C~
. C ( I
N

U ~ ~ d C ?. Vi I .
C

i~ _g: ~n ~. E a a o o E
c~ I ~ i ' I N C O
r. ~ ~ 0 0 ~
N .Q NI
~G

p ~.~ U ~ ..O L '~' ~ ~ ~ z ~ ' 2.v > '~ ! ~ , Q

.C ~ ~ = I
~ ~N O

O ~ c N ~ ' I
' >' ~ C ~ > I ~ 01 C7~ W
Gi ~ ' La U
N wp Y ~

_ a ~ I V C1 v ~ _. ffl ' t 1 ~ : ~
a~ ~

, V

~~~ ~~
~~I~. ~~

:~ ~ ~ - ~ a - ~ ~ c~ ~ c 3 ~
o ~

I ;
a ~~ ' ! > ca- ~ o I cn ~ .
.~ ~ ' ~
~

~ U 'n G T
~' I
~ .~
_tn t G ~
C% =
; ~
i' I

~ I G
~ ~ ~ ! c~c r -~
. c, ~ I
.. ~
~
>
'=
~
' G ~ ~ I a H G
~ ~ .~ E eN'c ~ -~
~

,I ~ th Vi U L _ . .
G. Z.
'' C
='.

U Q ~ j ' ' 3 ~ I 3 'J
~ I

'. I ~ I o iv ~ ' v . ~a ~ ~
~ I I
_- ;
I Vi "

p I _ "_ o, _o ~ i I ~ C
~ J C
' ~
a' I ~ h v ~
!-n I

V i ~

~ V
C ~ i I 1 i ~ t ' . I C ~ N ~ I_ _ I

~ ~ I
I C ~

O ~ o I'E ~
L , c ~ ; i o N
~
C

~ ,s ~ I ~ m . ,~.
L E . ~L ~ ' o ._ v -Ti ~ G I
p T ~c~ G
~

~ = ~ ~ G C O
.

~ C ?. ,~ ~ X 45 d O =~ _GO ~
~ c o D .
.

C E a~ ~ tL V U u m o c ~ c O ~ ~ ~ G _ L Q C ~ ~ .~ S U ~ C
' .c T p p I tSfC ~ = tHp >

J a . c m v ~.I is ~ U

.~ L a O , ~ ~ c~d? ~ ~ a, n~
c > I

i ~ ~ ~' ~ G U ~ -_ c -,, 'a v~~ 'v-, We c ~ oy ~ a ~ ~'c N O c ~

r - a ~ . > o ~ ( E ~ ' ' ~r i ~ c~ ~' ! ~ e 3 f- ~ > !t LrU ~ ~ C ~~ i I

~ O n.t I
I

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

Claims (2)

We claim:

1. A lighting device capable of being connected to a network.

2. A lighting device capable of being connected to a network, substantially as decribed herein.