IN THIS PPT YOU CAN LEARNT WORKING OF CHARGE COUPLED DEVICES AND APPLICATION,TYPES

1. RAGHU ENGINEERING COLLEGE
(AUTONOMOUS)
DAKAMARRI
M UDAY KUMAR
17981A04B8
ECE-C
TECHNICAL SEMINAR ON
CHARGE COUPLED DEVICES

2. OBJECTIVE
• Study and observe working and application of
charged coupled devices

3. INTRODUCTION TO CCD’s
• CCDs are used to convert light into a digital
value
• The CCD captures light and converts it to
digital data that is recorded by the camera.
• It can be defined as a light-sensitive integrated
circuit imprinted on a silicon surface to form
light-sensitive elements called pixels, and each
pixel is converted into an electrical charge.

4. TYPES OF CCD’S
There are different CCDs such as
• Electron multiplying CCDs,
• Intensified CCD,
• Frame-transfer CCD
• Buried-channel CCD.

5. WORKING
• They transfer incoming photons into an electrical
charge in the CCD chip
• The photons are received in a photoactive region
of silicon
• A lens is used to focus the light onto the silicon
• A charge is accumulated in the capacitors
proportional to the light intensity
• Each photo site corresponds to an
individual pixel in the final image and photo sites
are often referred to simply as pixels.

6. • Each “photo sites” will refer to the CCD chip
and “pixels” will refer to an image.
• When a photon of light strikes the surface of
certain metal materials the energy imparted
by the photon can release an electron from
the metal.
• In a CCD, this electron is stored within the
walls of a photo site

7. HOW TO GET DATA FROM CCD’S
• Photo sites are read out, one row at a time,
into a serial register along the bottom of the
CCD array.
• The serial register then transfers the charge
from each photo site to an output node.
• From there the charge is sent to the camera’s
electronics unit where the electrons are
digitized.

8. 8
CCDs can be used to collect an image in one of three ways,
either one pixel at a time, one row at a time, or as an entire area
at once.

9. How is an image made with a CCD
chip?
• There are three main phases:
 Clearing phase
Exposure or integration phase
 Readout phase
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10. How a CCD chip registers image?
• The telescope projects an image on the CCD chip. High
intensity areas will produce more charge in the pixels than
low intensity areas.
• The amount of charge in every pixel makes the image.
• The computer can read this charge and convert it to an
image
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oThe value in
every pixel gives
the charge,
which is related
to the light
intensity.

11. Clearing phase
• Mostly you don’t have a
shutter in your camera, this
means that there is always
light falling on the CCD chip.
• When you want to make an
image, all existing charge has
to be removed from the pixels.
• The lowest line will move the
charge to a clearing line,
where it will be removed.
• When all lines are shifted
away, there is no charge left
anymore
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12. Exposure or integration phase
• The lens projects the image on the CCD chip, so charge
will accumulate in the pixels.
• The longer you wait, the more light will be registered
by the chip.
• This phase controls the exposure time, also called:
integration time,
• because the chip integrates the amount of light in a
certain period. With lunar and planetary photography
it usually takes a few tenths of a second, but it can take
minutes or even hours

13. Readout phase
• To get the image in your computer, it
will have to read the amount of charge
of every pixel.
• There is a device, the charge detection
node, in the CCD chip that is able to
measure the charge of a pixel
• When all pixels of the line are
measured, all lines are shifted one line
down.
• Then again the lowest line can be
measured. This will be repeated until
all lines are measured.
• The computer can read the
measurements through the camera
electronics 13

14. Applications
• CCDs are used in digital cameras, optical
scanners and video cameras as light-sensing
devices.
• CCD cameras used in astrophotography.
• CCDs are typically sensitive to infrared light,
which allows infrared photography, night-vision
devices , video recording/photography.
• CCD are use to take exposures of galaxies and
nebulae
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15. Advantages
o Relative simple
o More sensitive than photographic film
o Cheaper to replace if failure
o Modularity-easy upgrades
o Detector costs simple
o No chemical processing is needed
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16. DISADVANTAGES
• CCD sensors consume much much more power.
• HD video-less pixel rates.
• CCDS are expensive as they require special
manufacturing.
• CCD sensors may be wired/wireless-mastering the
use requires some effort and learning period

17. REFERENCE
• https://www.elprocus.com/know-about-the-
working-principle-of-charge-coupled-device/
• https://en.wikipedia.org/wiki/Charge-
coupled_device