Flatbed width of a paper. The paper

Flatbed Input Devices

 

Scanner    

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What is a Scanner?

A Scanner is a
device which converts any physical paper to a digital one (which computers can
understand). 

 

What are different types of
Scanners?

·      Drum Scanner:

Drum Scanner is used to
scan higher resolutions of an image. There are Photomultiplier Tubes (PMT) in
Drum Scanner. The drum scanner rotates very fast and uses three different types
of PMTs, one for red light and another for green and the last for blue. While
rotating it passes through the front of the object and that front is being
scanned by the precision optics and the final data is sent to PMT and then to
computer.

·      CCD Scanner:

CCD is an abbreviation of
Charged Coupled Device .This is the
type of Scanner which we use in our daily life. There is an opening and a flat
surface where we have to keep the document which we want to scan. The surface
is covered and a ray of light passes through it and the document is scanned.

·      CIS Scanner

CIS Scanner or Contact
Image Sensor Scanner use an array of LEDs to shine light on the document so
the image sensor can essentially take a snapshot of it like we do by taking
images of the document, but this method is more accurate than taking images
through mobile phones and less accurate than CCD Scanner. CIS is cheaper, more
lightweight and more efficient technology to scan images. So it used in small
portable scanners which can be powered from solely USB port instead of requiring
a wall outlet.

·      Roller Scanner:

This type of scanner can
scan only a limited width of a paper. The paper is rolled around a rod which is
to be scanned and then rollers are rotated. This is very small and compact
scanner which can store in its memory or could be transferred to a computer
through USB port.

 

 

How does a Scanner work?

 

Scanner
uses something called as Charged-Coupled device (CCD) to scan a page. The CCD
can convert light into an electrical charge which then sends data to the
computer as digital data.  A ray
of light is released from the scanner which is due to a xenon lamp or a cold
cathode hits the paper and is reflected back underneath a glass surface then
focused by a lens onto an array of CCD sensors. The dark parts containing ink
on paper reflects less light then white portion. The CCD Arrays will analyze these
differences and will show up as an accurate image in the computer. The more the
sensors in the array the more pixels we get in the final image.

 

 

How does a Colour scanner
work?

 

Colour
Scanner uses different lenses to detect different versions of Red, Green and
Blue colour to scan any colour.

 

What is the future of
Scanners?

 

Nowadays
phone has a scanner which converts the document to an image format or a PDF
format using some machine learning algorithms which eliminates the useless
parts of background (like user’s hands while capturing image).

Apart from
that nowadays 3D Scanner technology is developing. They scan a
three-dimentional object.   

 

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