BACKGROUND OF INVENTION
-At the present time, it is desirable in street lighting systems employing multiple luminanes
- that 'the lamps therein are rum ON in response to decrease in the level of illumination and are
turn OFF in response to increase in the level of illumination. With such a system, it is
5 possible that under varying atmospheric conditions, proper illumination of streets and
surrounding areas may be achieved automatically without depending upon any human
element. From the decade of 1950's to now there are different approac-hes to accomplish
automation of street lightning system. It starts from using a photocurrent from a photoelectric
cdl in conjunction with a polarized relay, which relays have been quite expensive and which
10 expense has prevented their universal adoption. Further non-polar relay is used in
combination with photodiode. Since the photo diode produces very small photo current
therefore thermionic amplifier is used and such amplifiers required periodic replacement.
Some of the invention uses two relay one polar relay for energizing the non-polar standard
rday, which made the system "fail safe" i.e. upon failure the light is energized which is
15 desirable in street lightning system. In further invention DC electromagnet relay which is
encountere~ to arching and chattering. IJ:?. present some of invention r~lated to same purpose
is carried out using RFID technology which is capable of predicting current magnitude of
lamp, auxiliary sensor input, data storage for street light monitoring system, diagnostic
alarming. This system can communicate to street light system in peer-to-peer fashion to data
20 collection point but simultaneously execution of this system is expansive and maintenance
cost is high. One of the most recent invention is a pre-programmed universal forward-looking
calendar can predict sunrise and sunset times in a known way by latitude or time zone. That
calendar can include a pre-set number of programs to control the actual on/off cycle of a
streetlight. However cost effectiveness of this approach at ·each lamp is difficult.
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SUMMARY OF INVENTION
Accordingly, one object of my invention is to provide a new and improved control circuit for
street lighting purposes which utilizes two sensors namely Light dependent resistor and
--- --- -- - -··--infrared-sensor in conjunction witfr.micro,controller.-Working-of.this circuit is controlle.u~ly reads input from LDR (ligh!
dependent register) and IR (infrared) sensor then decides smartly that whether street light
should turned on or not. Applicant has created a process for synchronizing on and off time of
street lamps, according to local environmental conditions. The given embodiment is
independent of clock time an~ dep;mds o1n7the.l~ous intensity of enviroruner~ • ·•
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35 · ·· Another object of my invention is to provide an intelligent control circuit for street ligbt
which is unaffected from p1.1ls.ating light sources i.e. other light sources such as light from
.vehicle and laser point can't fool the streetlight controller and can't tum streetlight oft
BRIEF DESCRIPTION OF DRAWINGS
40 The above and other ohjects will become more readily apparent when the following
description is read in conjunction with the accompanying drawings, in which:
FIG. 1 is a flow chart showing an embodiment of Applicant'~ "HJGNU : An intelligent
streetlight control system" uses a light dependent register, infrared sensor, Optocoupler
integrated circuit, triac/contractor and micro-controller to tum on streetlight when intensity of
45 light in environment falls below predetermined value and turned off the streetlight when
intensity of environmental light exceeds predetermined value.
Fig. 2 depict the circuit diagram of an embodiment of Applicant's "JUGNU : An intelligent
streetlight control system"
so DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)
My invention disclosed alternative methods, for automatically synchronizing the on and off
time for streetlights by sensing and analysing local conditions without human intervention.
My approach is to: sense intensity of light in the environment and amount of infrared
radiation contained in the same luminance, when dusk occurs the intensity of light falls as
55 well amount of infrared radiation contained by it also decreases on the other hand When
dawn occurs the intensity of light and amount of infrared radiation contained by it will also
increases. The light dependent resistance senses intensity of light and infrared .sensor senses
amount of infrared radiation in environmental light continuously. Then these two sensors
continuously sends signal to the input of micro-controller and on the basis of these input
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micro-controller decides whether to tum streetlight on or off.
1. FIG. 1 depicts Applicant's alternate process as a block diagram. When power is given to
the circuit the algorithm starts(at step 100), micro-controller initializes (at step 101) with
constant values LDRx and IRx embedded in it at the time of programming, then reads value
from light dependentresistor sensor (at step 102), Then micro-controller checks for condition
whether the present value of LDR sensor is greater than the value of constant· LDRx stored
(i.e. pre-set value) in micro-controller (at stage 102) or not and ifthe present value ofLDR
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sensor is greater than the pre-set value the streetlight remains off and loop continuously
follows the same path till the present value of LDR decrease beyond the pre-set value
LDRx. When value of LDR's sensor decrease beyond pre-set value (i.e LDRx) then micro-
70_ _co _~trol!er r~~~s the value ofinfr~ed sensor (at step 103) ~!d th_en co~pare infrared sel!sor's
value to pre-set value stored (i.e IRx) in micro-controller (at step 104). If the present value of
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-infrared sensor is-liiglier than pre-set value the streetlight remains off an(:rifcurrent value of
infrared sensor reduced below pre-set value then the micro-controller (J...t1) turns the street
light ON(at step 104). When the streetlight turned on the micro-controller waits for T1 minute
(at step 105), then micro-controller reads value at lig.h t- dependent resistor and set this value
as Intensity Level (at st-ep 1~6~. A~er that. m~c~o~controller continuously readinr_;l~o->m
U"ELHI 0 l- 06- l 0 l 5 17 -3lS 1'"\"'f; ~
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..• infrared sensor and simultaneously compare it to pre-set value IRx (at step 107). lfthe.value
of infrared sensor exceeds . the pre-set value IRx then the micro-controller waits for T 2
Seconds (at step 1 08) and.microcontroller again reads the value of light dependent res~stance
80 (at step 1 09). If the value of light dependent resistance is higher than Intensity Level (present
value of light on Read Sensor!) then the streetlight turns off and if greater than or equals to
Intensity Level then the streetlight remains in on state. This algorithm is continuously
executed by microcontroller if power supply is provided to the circuit. The following are
details of variables used in the flow chart:
85 1. LDRx. Value of constant defined inside the microcontroller at the time of initializing for
comparing to the value coming from the LDR sensor.
2. IRx. Value of constant defined inside the micrucontroller at the time of initializing for
comparing to the value of IR sensor.
3. Intensity Level value of variable just after the T1 minute of light on used for comparing to
90 the LDR sensor value.
4. T1 is the time interval (in minutes) after street light turns on.
5. T2 the time interval (in seconds)
6. Values ofLDRx, IRx, T1 and T2 can be modified according to the need.
FIG. 2 depicts the circuit diagram of the invention. The whole circuit can be divided into four
95 parts for understanding it more clearly, these parts are: Switch mode power supply (1),
controller circuit (2), load driving circuit, sensing circuit and indicating circuit.
100
105
110
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The Switch mode power supply (1) is of DC 5 volt 1 ampere. The load driving circuit
consists of a PNP transistor (11), resistances (10, 12 and 14), optocoupler integrated circuit
(13), TRIAC and AC power source (17).
Sensing circuit consists of infrared sensor module and Light dependent resistor module. The
infrared module has infrared sensor (8) and resistance (9). The Light dependent resistance
module has Light dependent resistance (6) and a resistance (7). Indicator unit consists of red
(8), green (9) LEDs and a resistor (5).
The system has two sensors namely infrared sensor (8) and Light dependent resistance (6).
Both the sensors are connected to microcontroller unit (2) in voltage divider arrangement.
Thus the va}J.1es from LDR(6) and IR sensor(8) are converted into simultaneously varying
voltages according to the environmental conditions. The voltages from these voltage dividers
act as input for the microcontroller. Microcontroller programmed according to the flowchart
.It takes input and decides either to tum ON or OFF the light. For this purpose it sends a
signal to base ofPNP transistor. As microcontroller is unable to handle heavy loads properly,
the transistor is used as a switch in reverse fashion. To tum the light ON the base of transistor
is made low and vice versa. So to tum light ON, microcontroller needs to send a low signal to
the base of-F-NP-transistof-. -Since-here-transistor is used as a switch,-When the-base-ef----·
transistor is m(!Qe low Optocoupler_ge_ts_activated thus the pins of othey ~ide pf Optocou~I_~r. _
IC switches the Triac. As soon as AC starts flowing through the gate of triac, bulb
(load/lamp) switches ON till the optocoupler IC switches it. The indicting LEDs are able to
indicate ON/OFF conditions separately (i.e. if the light is ON one LED starts glowing and if
the light (lamp/Joad) is OFF other LED starts glowing while the one switches of.
The discloser is equally applicable to any outdoor light to -illuminate outdoor areas such as
120 _ road side, highways, buildings, parks and other places where illumination is required.

What is claimed is:
1. A method for controlling streetlights and capable of differentiate between sun light and
artificial light up to an extent, the method comprising:
a microcontroller,
125 a first sensor light dependent resister coupled with said microcontroller and operative to sense
the luminous intensity of the environmental light~
a second sensor infrared sensor coupled with said microcontroller and operative to sense
amount of infrared radiation in the environmental light,
a switching circuit coupled with said microcontroller and operative to switch on and off. ·the
130 streetlights. The switching circuit turns the streetlights on when microcontroller gives low
signal to it and turns streetlights off when microcontroller gives it high signal.
2. The method in claim 1 wherein the switching circuit further comprises: a PNP transistor
operative to switching optocoupler IC. The optocoupler IC is operative for switching of triac
as well as isolating DC microcontroller circuit and AC load circuit.
135 3. The method of claim 2 wherein the. switching circuit further cotpprises of triac circuit
which
connects the load to the source when microcontroller gives high signal to it via optocoupler
and transistor.
4. The method of claim 1 wherein the first LDR sensor operable to sense environmental light
140 level and second sensor operable to sense amount of infrared radiation in environmental light
the output of these two sensors read continuously by microcontroller. On the basis of the
output of these sensors microcontroller detect whether to switch on or switch of the street
light.
5. The method of claim 1 is independent to switch on the streetlights during day time as well,
145 if the intensity environmental Hght fall beyond the threshold value and then automatically
switch off the street light when intensity of light rise above the threshold. During rainy season
when clouds are quite dark it will switch on the streetlights and turn it off when clouds are
6. The method of claiml wherein the on and off times for-the streetlight are determined by--
150 sensing and analyzing environmental conditions without human intervention.
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7. The method of claim 1 wherein the inventor differentiate between sunlight and artificial
light on the basis of richness of infrared radiation in the sunlight whereas most artificial light
heaving very low amount of infrared radiation. In the night time the system can't fail due to
effect of thundering and or any other pulsating light sources.