This document discusses image sensors, including what they are, their history, types (CCD and CMOS), and applications. An image sensor converts light into digital signals and contains millions of photosensitive diodes. The two main types are CCDs, which store and transfer electrons, and CMOS sensors, which can incorporate additional circuits. While CCDs generally have better image quality in low light, CMOS sensors are smaller, cheaper, and more power efficient. Image sensors are now widely used in applications like digital cameras, camcorders, PDAs, fingerprint scanners, and more.

1. SEMINAR
ON
IMAGE SENSOR

2. CONTENTS
o What is a Sensor?
o Types of Sensors
o What is an Image Sensor?
o Types of Image Sensors
o What is CCD?
o What is CMOS?
o CCD vs CMOS
o Applications of Image Sensors
o Conclusion

3. WHAT IS A SENSOR?
 A sensor is a device that measures a
physical quantity and converts it into a
signal which can be read by an observer or by
an instrument.
 For example, a thermocouple converts
temperature to an output voltage which can
be read by a voltmeter.
 For accuracy, all sensors need to be
calibrated against known standards.

4. TYPES OF SENSORS
 Thermal Energy Sensors
 Electromagnetic Sensors
 Mechanical Sensors
 Chemical Sensors
 Optical and Radiation Sensors
 Acoustic Sensors
 Biological Sensors

5. WHAT IS AN IMAGE SENSOR?
 Unlike traditional camera, An Image Sensor is a photosensitive
device that converts light signals into digital signals (colours/RGB
data). It uses film to capture and store an image.
 Image sensors contain millions of photosensitive diodes known as
photosites.
 When you take a picture, the camera's shutter opens briefly and
each photo site on the image sensor records the brightness of the
light that falls on it by accumulating photons. The more light that
hits a photo site, the more photons it records.
 The brightness recorded by each photosite is then stored as a set
of numbers (digital numbers) that can then be used to set the
color and brightness of a single pixel on the screen or ink on the
printed page to reconstruct the image.

7. IMAGE SENSOR HISTORY
 Before 1960 mainly film photography was
done and vacuum tubes were being used.
 From 1960-1975 early research and
development was done in the fields of CCD
and CMOS.
 From 1975-1990 commercialization of CCD
took place.
 After 1990 re-emergence of CMOS took place
and amorphous Si also came into the picture.

8. TYPES OF IMAGE SENSORS
An image sensor is typically of two types:
1. Charged Coupled Device (CCD)
2. Complementary Metal Oxide
Semiconductor (CMOS)

9. WHAT IS CCD?
 Charge-coupled devices (CCDs) are silicon-based
integrated circuits consisting of a dense matrix of
photodiodes that operate by converting light
energy in the form of photons into an electronic
charge.
 Electrons generated by the interaction of photons
with silicon atoms are stored in a potential well
and can subsequently be transferred across the
chip through registers and output to an
amplifier.

10. CHARGED COUPLED DEVICE (CCD)

11. WHAT IS CMOS?
 “CMOS" refers to both a particular style of digital
circuitry design, and the family of processes used
to implement that circuitry on integrated circuits
(chips).
 CMOS circuitry dissipates less power when
static, and is denser than other implementations
having the same functionality.
 CMOS circuits use a combination of p-type and n-
type metal–oxide–semiconductor field-effect
transistors (MOSFETs) to implement logic gates
and other digital circuits found in computers,
telecommunications equipment, and signal
processing equipment.

12. COMPLEMENTARY METAL OXIDE
SEMICONDUCTOR (CMOS)

13. CCD VS CMOS
 CMOS image sensors can incorporate other circuits on the same
chip, eliminating the many separate chips required for a CCD.
 This also allows additional on-chip features to be added at little
extra cost. These features include image stabilization and image
compression.
 Not only does this make the camera smaller, lighter, and cheaper;
it also requires less power so batteries last longer.
 CMOS image sensors can switch modes on the fly between still
photography and video.
 CMOS sensors excel in the capture of outdoor pictures on sunny
days, they suffer in low light conditions.
 Their sensitivity to light is decreased because part of each
photosite is covered with circuitry that filters out noise and
performs other functions.
 The percentage of a pixel devoted to collecting light is called the
pixel’s fill factor. CCDs have a 100% fill factor but CMOS cameras
have much less.

14. APPLICATION
OF
IMAGE SENSORS

15.  Digital Cameras

16. PERSONAL DIGITAL ASSISTANCE
(PDA)

17. CAMCORDERS

18. TOYS AND ROBOTS

19. FINGERPRINT SCANNER

20. SOME OTHER
APPLICATIONS
Biometrics.
Optical Mouse.
Video Conferencing.

21. CONCLUSION
 Image sensors are an emergent solution for
practically every automation-focused machine-
vision application.
 New electronic fabrication processes, software
implementations, and new application fields will
dictate the growth of image-sensor technology in
the future.