colour sensor vivek
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Design of a
Colour Sensor
By:
VIVEK KR. SRIVASTAVA
Roll No. 210403
Under the guidance
of
DR. S.K. MAHNA
OUTLINE:ObjectiveColour TheorySystem IntroductionThe Optical SystemThe Electronic SystemDecoding ActionFuture Scope of the ProjectApplications
OBJECTIVE:
To design a sensor which can detect
light of different colours and is able
to differentiate between them.
COLOUR THEORY:
Primary colours are sets of colours that can
be combined to make a useful range of colours.
For human applications, 3 primary colours are
usually used, since human colour vision is
trichromatic.
A secondary colour is a colour made by
mixing two primary colours in a given colour
space.
PRIMARY AND SECONDARY COLOURS:
PRIMARY COLOUR:Primary colour can be subdivided into:
PRIMARY COLOUR
ADDITIVE SUBTRACTIVE
ADDITIVE PRIMARY:An additive colour model involves light
emitted directly from a source or
illuminant of some sort.
Combining one of these additive primary
colours with another in equal amounts
produces the additive secondary colours.
Combining all three primary lights
(colours) in equal intensities produces
WHITE.
RGB COLOUR MODEL:
An additive colour model in which RED,
GREEN, and BLUE light is added
together in various ways to reproduce a
broad array of colours.
Used in sensing, representation, and
display of images in electronic systems,
such as televisions and computers.
RGB COLOUR MODEL:
SUBTRACTIVE PRIMARY:
A subtractive colour is based on
absorption phenomenon.
Each colour is caused by subtracting (that
is, absorbing) some wavelengths of light
and reflecting the others.
This model explains the mixing of paints,
dyes, inks, and natural colourants to
create a full range of colours.
RYB COLOUR MODEL Primarily used in art and design
education, particularly painting.
SYSTEM INTRODUCTION:
BLOCK DIAGRAM
COLOUR LIGHT SOURCE
(RGB)
SENSORS(Light To Current)
SIGNAL CODITIONING OUTPUT
OPTICALCOMPONENTS
LIGHT
Light rays from a colour light source
fall on the optical components of the
Colour Sensor.
The optical components filter and
focus the rays on the optical sensors.
The output of the sensors is processed
by the electronic circuitry and the
corresponding colour output is
obtained.
THE OPTICAL SYSTEM:Photodiode Convex
lens
Colour glass filter
Hollow cylindrical pipes
10cm 10cm
OPTICAL COMPONENTS USED:
PHOTODIODE – (EG & G)
PIN Photodiode
Based on Photoelectric Effect
Converts Light to Current
CONVEX LENS (f = 5cm)
Performs the task of focusing the light
on the sensor.
OPTICAL COMPONENTS USED:
COLOUR GLASS FILTERS (Blue, Red,
Green)
Allows only single colour wavelength to
pass through it.
The optical filters used in the system are
absorption filters.
It consists of colour media like colour
glasses.
THE ELECTRONIC SYSTEM:
ELECTRONIC COMPONENTS USED:
PHOTODIODE
Connected in Reverse Bias.
Outputs current proportional to the incident
light intensity(~20µA).
OP-AMP –UA741
Connected as a trans-impedance amplifier.
Converts current into voltage.
ELECTRONIC COMPONENTS USED:
DECODER – 74HC138 3 x 8 decoderTakes 3 inputs and gives 8 outputs
VOLTAGE REGULATOR- IC 7805
Gives a fixed output voltage of 5 Volts
Need of the regulator?
The decoder IC operates on 2 to 6 Volts
The output of the op-amp can be as high as
12 volts
DECODING ACTION:INPUT OUTPUT
A2(Green)
A1(Red)
A0(Blue)
COLOUR DETECTED
0 0 0 0 1 1 1 1 1 1 1 NO COLOUR
0 0 1 1 0 1 1 1 1 1 1 BLUE
0 1 0 1 1 0 1 1 1 1 1 RED
0 1 1 1 1 1 0 1 1 1 1 MAGENTA
1 0 0 1 1 1 1 0 1 1 1 GREEN
1 0 1 1 1 1 1 1 0 1 1 CYAN
1 1 0 1 1 1 1 1 1 0 1 YELLOW
1 1 1 1 1 1 1 1 1 1 0 WHITE
FUTURE SCOPE OF THE PROJECT The system can be modified to
detect the colour of an object by sensing the light reflected by it.
The system can be interfaced with a microcontroller to detect a wide range of colour shades.
APPLICATIONS:
It can perform sorting operations:
◦ Avoids separation of medicines in
pharmaceutical industries.
◦Brick sorter
◦ In the recycling industry, sorting plastic by
colour for recycling purposes. For eg. all
the green 7-Up bottles down one
conveyor, the clear on another and so on.
THANK YOU
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