ANNEXURE- COMPLETE SPECIFICATION
TITLE:
An Intelligent and Interactive Street lighting Luminaire with LED Light Sources

1) PRODUCT NAME:
An Intelligent and Interactive Street lighting Luminaire with LED Light Sources
2) OWNER OF PRODUCT AND ADDRESS:
Owner:
MIC Electronics Limited A Public Limited Company
Address:
A - 4/11, Electronic Complex, Kushaiguda, Hyderabad - 500 062 INDIA.


3) BACKGROUND AND OBJECTS OF THE INVENTION:
The present invention relates to grid or solar powered street lighting luminaires using LED light sources with advanced features like optics, networking and embedded electronics for remote monitoring and control. A Luminaire provided with effective control of light intensity, desired light spread, protection against various erroneous operating conditions and suitable for networked operations is presented.


4) PRIOR ART: PATENTS AND DESIGNS:
Street lighting systems have been in existence since long, and their operational control and efficiency have been constantly addressed for improvements.
Street lighting systems consist of a generic configuration as below:
A lighting enclosure or housing
A light source
An optical system
A light sensor
Drive electronics for the light source
A power source
A facility for on / off switching
Street lighting systems employ housings that are essentially made of metal in a shape convenient to accommodate and maintain the light sources with associated optics and power electronics. The designs aim at providing desired illumination levels on the road. The metal housing is covered with a transparent glass flat plate downwards, which allows the light to illuminate the road. The street lights are switched on / off manually or automatically through electronic controls with limited dimming capability.
Conventional street lights employ HID light sources like sodium vapor or metal hallide lamps to provide desired levels of illumination on the road. LED light sources are being introduced to take advantage of the inherent merits of energy efficiency and long life resulting in a eco-friendly solution with substantial operational economies.
References
1. Indian patent application; Dec 2007
Intelligent Solar Lighting System
No. 3039/CHE/2007A dt 19-12-2007
published on 11-01-2008
2. Indian patent application: Dec 2007
Programmable LED Illumination Systems
No. 3038/CHE/2007A dt 19-12-2007
published on 11-01-2008
3. Indian patent application: July 2007
Intelligent LED Street Light System
NO.I153/DEL/2007 dt 03.05.2007
published on 06-07-2007

Our copending Indian Patent application (referred in 1 above) dated Dec 2007 outlined a methodology for on / off control of solar streetlights using RF / GSM / GPRS / CDMA receiver and sensor bypassing the ambient light sensor when RF is active.
Another copending Indian Patent application of ours (ref 2 above) dated Dec 2007 outlined a method for programming and controlling several lighting luminaires for on-off switching or intensity control.
Indian Patent application (ref 3 above) published in July 2007 proposed the concept of intelligent LED street lights as a solution for Sodium vapor lamps due to the technology benefits of LEDs.


SHORTCOMINGS OBSERVED IN PRIOR ART:
LEDs with their superior light output, long life and high efficacy have been realised as a better choice to other light sources.
Further, due to the limited life of conventional HID light sources, replacements or maintenance requirements are frequently needed on burnouts. It is a cumbersome process as the streetlights are located at unmanageable heights. LEDs overcome such need because of their long life and no burnout.
However there are few concerns to be addressed in the LED based streetlights:
LEDs are point light sources and create glare, a vital issue resulting in non-uniform light distribution in the area under coverage. The circular illumination pattern is more intense at the center and gradually tapers towards the periphery.
The heat dissipation inside the enclosure also affects the life / colour of the LED light source. The characteristics of the light source undergo variations resulting in undesirable performance.
Automatic on / off switching can also be efl'ected by using ambient light sensors. Dust or dirt or water settled on the sensor or a dusty or cloudy ambient, could create ambiguity in sensing the ambient light and as a result, an incorrect decision may be made by the system to switch ON the lights when actually not required.
Further the street light luminaires of the present art are controlled individually or collectively for switching on / off only with limited dimming facility. Monitoring several of them for operations and maintenance is a time and energy consuming task. In order to monitor and control large number of luminaire units, a methodology is needed which takes advantage of contemporary technologies.
The present invention seeks to provide a lighting system - a luminaire - that addresses these shortcomings.


6) PREFERRED EMBODIMENT OF THE PRESENT INVENTION:
The present invention provides an embodiment of the lighting system luminaire which includes an external housing to integrate a light source, optics, light sensor and the electrical power source to offer an efficient street lighting system. In particular, the optical system and the light sensor provide a method and apparatus for improved light intensity / light spread and an improved control of the lighting system in ambiguous ambient situations.
The optics (or the lens) design attempts to make a rectangular area (from out of the circularly illuminated pattern otherwise) under the luminaire uniformly illuminated. This is necessary in the case of streetlights used for lighting the roads or streets, particularly highways and other important roads.


7) BRIEF DESCRIPTION OF THE DRAWINGS:
Embodiments of present invention will be discussed with the help of the following diagrams:
Fig 1 Lighting fixture with lens
Fig 2 Lighting fixture without lens
Fig 3 Schematic diagram
Fig 4 Lens system
Referring to Fig1 and 2, a lighting fixture for street lighting comprises a housing 10, which forms an enclosure to contain the light source, such as an LED configuration with lens 20 or without lens 30, electronics 40, an electrical power source and an ambient light sensor 50. The electronics further contains LED driver, signal processing unit, RF antenna, switches and fuses (protection systems). The shape is designed for withstanding aerodynamic wind pressures, and at the same time fitting the lighting devices with proper directivity to prevent light losses in undesirable directions. The housing is covered with a transparent toughened glass sheet 60 tightly fitted with the help of a gasket 70. The luminaire can be installed on a pole by means of a clamp 80. The cover 90 of the housing is designed with fins for heat radiation.
Referring to Fig 3, the Schematic Block Diagram, Grid power supplied to the pole is connected to the line, neutral and earth inputs of the lighting fixture. The DC voltage required is derived from the grid power and is supplied to the drive electronics.
For grid less operation, necessary PV panels are arranged to receive the solar energy. Charge control unit and batteries are accommodated in a box fitted on to the pole.
Fig 4 depicts the design of optical lens used in conjunction with the LED light source in order to realise the targeted light spread.


8) DESCRIPTION OF A PREFERRED EMBODIMENT AND METHOD:
The luminaire is designed to control glare with provision for full cutoff, semi cutoff or non cutoff. The spread of the light in length is improved to optimize number of poles per kilometer stretch of the road. The shape and the lens in the optical system are packaged in an efficient way following international and Indian standards (CIE, lESNA and BIS ) to arrest light distribution in undesired directions. LEDs are connected in series and in parallel in sufficient numbers to obtain the light intensity levels of interest. In this method, failure of a single LED will not make the system to fail totally, ensuring reliability. The LED drive circuit has the drive electronics needed.
The light sensor is an adjustable upward or downward looking light sensor. In the upward looking orientation, the light sensor constantly senses the ambient light and triggers the street light ON and OFF at pre-defined lux levels. The light sensor contains a photo sensor and a holder. The luminaire has an additional functionality of compensating for an incorrect reading of the ambient due to dust or clouds or shade of a tree etc by means of a generic real time based algorithm, which switches the luminaire ON / OFF based on time of the day. In the downward looking arrangement, the light sensor senses the light intensity of the LED and should there be any deterioration in the lumen output over age, a feedback circuit changes the drive current to compensate for the loss and restore the lumens.
The housing is made of high thermal conductivity material - die cast aluminium - which passes the heat developed inside to the external fins and radiating sources. The thermal analysis and design is realised through an iterative process of empirical formulations and computer based simulations for efficient heat transfer. The design also caters to the functional requirements, structural requirements and aesthetics. Additionally, the heat generating LED light sources are assembled on Metal Clad / Metal Core PCBs (MCPCB) which help in taking the heat away from the source to the housing to safeguard the LEDs by maintaining the junction temperatures within limits, thereby ensuring long operating life without degradation in the lumen output. The temperature sensor mounted on the MCPCB constantly monitors the temperature in the enclosure and as the temperature crosses a specified safe limit, switches the street light OFF (or dims) and on cooling back to safe limit, automatically switches ON the street light. Thus the luminaire is protected from any damage due to heat. Further, the housing is protected from all weather conditions (heat, dust, rain or wind) by suitably rated Ingress Protection IP65.
Progressive dimming of the light Intensity of the luminaire Is achieved through a programmable timer or a real time clock with suitable modulation of the drive currents. PWM methodology is used for this purpose as this does not allow any color shift. Another feature allows the illumination level to be reduced to half its normal level during late night hours by suitable timing based interrupts from the real time clock, to save energy.
The street lighting system has built in safety features for over-voltage or under-voltage. Whenever the neutral floats, making a high voltage to appear at the AC input, the system trips through a cut-off fuse. Thus the system survives through accidental over-voltages. System trips on under-voltage also in a similar manner.
The RF antenna and associated networking electronics enable remote monitoring and control. Zig Bee protocol is employed for remote monitoring, control and reprogramming. Remote monitoring and control are achieved through the web. Networking of a cluster of streetlights enables a simpler means to control all or some of them together. This is realised through the use of interactive map based GPS for remote control. A network of street lights is connected to a central place through concentrators over cost


effective wireless communication set up like GSIVI / CDMA. The authorities can monitor and control the operations of street lights as well as maintain archives of performance data through a web enabled application software.
Micro controller based data acquisition and control system provides the intelligence needed in respect of the data capture, processing, control and communication.
The design also ensures a very low standby current when the lighting system is not turned ON.
Street light luminaire models with typical power outputs ranging from 10W to 150W are contemplated for demand assessments. The data sheets / test results for few of these models is appended along with the photometric results.
Optics Design
The objective of optics (also called secondary optics) for the LEDs in any configuration including the street lights is to modulate the direct light output of LEDs (primary light source) and achieve the desired illumination pattern on the target area i.e. road and street.
Design of optics depends on the LED type and the light distribution pattern from the LED source. The aim is to design optics for the LEDs to project uniform light on the street and road as per CIE, lESNA and BIS standards. The design is expected to increase the spread of light along the road with uniform illumination all over, thereby reducing the number of poles per kilometer.
Design Methodology
Since the design is intended to project the light along the road, for about a distance of 5-6 times the mounting height, light traversing distance is minimum for area directly under the luminaire and increases as the light-falling area moves away from the pole as shown below:

To achieve uniform illumination on the road, more intense light beam must emerge from the luminaire (candela of the lamp should be more) at higher vertical angles than at lower vertical angles. Accordingly, the relative candela polar diagram can be estimated as under to satisfy this requirement of uniform illumination:

We claim
1. A street lighting luminaire comprising of grid converted DC power or solar
based DC power to drive a plurality of white LED light sources connected in
strings in sufficient numbers to provide desired level of illumination (lux level)
from a desired height.
2. The said street lighting luminaire of claim 1, wherein the LED light sources
are provided with secondary optics or lens for achieving a uniform light
spread.
3. The said street lighting luminaire of claim 1, wherein the LED light sources
are triggered ON or OFF by sensing the ambient through an ambient light
sensor.
4. The said street lighting luminaire of claim 1, wherein a generic algorithm is
implemented to provide for correction to any ambiguous ambient light
measurement due to cloud, dust, dirt or water.
5. The said street lighting luminaire of claim 1, wherein the street lights can be
interconnected in a network with facility for remote monitoring and control
using Zigbee protocol.
6. The said street lighting luminaire of claim 1, wherein the data pertaining to
light intensity, temperature, power etc are captured and logged for archives at
a centrally located web server and control signals are transmitted to the
luminaire for effecting the controls in wired or wireless modewith GSM /
CDMA technologies; the intelligence needed for data capture and control are
achieved through a micro controller. '
7. The said street lighting luminaire of claim 1, wherein provision exists to
protect the luminaire from accidental under voltage or over voltage or over
temperature.
8. The said street lighting luminaire of claim 1, wherein programmed
progressive dimming of the light source is effected by means of a timer or a
real time clock and the intensity can be reduced to any desired level in the
late night hours to save power.
9. The said street lighting luminaire of claim 1, wherein the housing is protected
from environmental conditions with IP65 rating.
10. The said street lighting luminaire of claim 1, wherein the housing and the
MCPCB are designed for effective thermal management to ensure long life of
theLEDs.