2. Color sensor
Outline:-
Objectives
Color theory
System introduction
Optical system
Electronic system
Application
Objectives:-
To design a sensor which can detect light of diff color and able differentiate
between them.
Color theory:-
Primary and secondary colors:
Primary colors:-
Primary colors are sets of colors that can be combined to make a useful range of
colors. For human applications, 3 primary colors are usually use, since human
color vision is trichromatic, primary colors subdivide into Primary Color Additive
Subtractive .
Secondary color:-
A secondary color is a color made by mixing two primary colors.
3. Subdivision of primary color:-
Primary colors dividein 2 parts.
Additive primary:-
An additive color model involves light emitted directly from a source or illuminant
of some sort Combining one of these additive primary colors with another in
equal amounts produces the additive secondary colors Combining all three
primary lights (colors) in equal intensities produces white.
RGB Color Modeling:-
Primary color
Additive Subtractive
4. An additive color model in which RED, GREEN, and BLUE light is added together in
various ways to reproduce a broad array of colors Used in sensing representation,
and display of images in electronic systems, such as televisions and computers.
Subtractive primary:-
A subtractive color is based on absorption phenomenon. Each color 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 colorants to
create a full range of colors.
System introduction:- (Block Diagram)
Light rays from a color light source fall on the optical components of the Color
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 color output is obtained. Photodiode is used in optical component.
Color light
source Optical
Component
Sensor
Signal
Conditionin
g
Output
6. LM324 IC:- (Comparator)
LM324 comparator can compare 4 pairs of voltages. For a single IR sensor, only
one channel is enough. Here we would be using pin 1,2 and 3 for our sensor.
7. Lm324 is a 14pin IC consisting of four independent operational amplifiers (op-
amps) compensated in a single package. Op-amps are high gain electronic voltage
amplifier with differential input and, usually, a single-ended output. The output
voltage is many times higher than the voltage difference between input terminals
of an op-amp, these op-amps are operated by a single power supply LM324 and
need for a dual supply is eliminated. They can be used as amplifiers, comparators,
oscillators, rectifiers etc. The conventional op-amp applications can be more
easily implemented with LM324.
Input voltage at pin2 > input voltage at pin3 ; Output1=> logic 0
Input voltage at pin2 < input voltage at pin3 ; Output1=> logic 1
Connect the output of our sensor(photo diode) circuit to pin2 & connect
potentiometer to pin 3of this IC. When the output coming from sensor is high
then final o/p is 0.but when the output coming from sensor is low then final
output is 1 , We also uses phototransistor, resistors and potentiometer for getting
output we placed LED’s.
Applications:-
It can perform sorting operations Avoids separation of medicines in
pharmaceutical industries. Brick sorter in the recycling industry, sorting plastic by
color for recycling purposes. For example all the green 7-Up bottles down one
conveyor, line follower reborts is also one of its application and so many apps.
