SCANNERS

CREATED BY NIKHIL JHA

UNIGLOBE COLLEGE

OBJECTIVES

TO KNOW ABOUT DIFFERENT TYPES OF SCANNER

TO UNDERSTAND THEIR WORKING PRINCIPLE

What is Scanner?Scanner is device that optically scans images, printed texts, handwriting, or an object and converts it into digital image.

The first scanner developed for use with a computer, was a drum scanner . It was built in 1957 at the US National Bureau of Standards by a team led by Russell A. Kirsch, working on America's first internally programmable (stored-program) computer, the Standards Eastern Automatic Computer (SEAC).

TYPES OF SCANNER BARCODE SCANNER FLATBED SCANNER

DRUM SCANNER

HANDHELD SCANNER

FILM SCANNER

BAR CODE SCANNER

SIMPLE PHYSICS OF REFLECTION

1= Led/Fluorescent Light emitter2= Barcodes3= Photoelectric cell4= CCD(Charge Coupled Device)5= Computer

1 A bar code consists of white and black bars. Data retrieval is achieved when bar code scanners shine a light at a bar code, capture the reflected light and replace the black and white bars with binary digital signals.

2 Reflections are strong in white areas and weak in black areas. A sensor receives reflections to obtain analog waveforms.

3 The analog signal is converted into a digital signal via an A/D converter. (Binarization)

4 Data retrieval is achieved when a code system is determined from the digital signal obtained. (Decoding process)

UPC (universal product code)

LASER METHOD

Laser light is shone on the label surface and its reflection is captured by a sensor (laser photo detector) to read a bar code. A laser beam is reflected off a mirror and swept left and right to read a bar codeUsing laser allows reading of distant and wide bar code labels.

PEN METHOD

This method only has a LED light source and a sensor to capture its reflection. Since a person moves a scanner to read a bar code, practice is required for operation.The mechanism is simple, making this method inexpensive.

CCD METHOD

The CCD method bar code scanner has a built-in light. A scanner shines this light at a bar code and its reflection is captured via CCD for reading.A bar code is captured once, allowing fast reading. There are no movable parts and impact resistance is excellent.

FLATBED SCANNER

Along with the glass bed, the scanner has a source of light, which is in-built. Most commonly the light used is LED or fluorescent. This light is regulated by a voltage regulator or a similar device. This enables the light to spread evenly across the document.

This light source then illuminates the document, this is when the actual encoding of the document takes place. The scanner contains a lens, mirror a filter and a CCD array, that are fixed on the top, called the scan head. This combined mechanism then rolls or moves over the entire document. The scan head takes help of a belt.

The scan head is fixed to a bar that acts like a stabilizer. So the entire process takes place smoothly, without any wobble or deviation.

An angled mirror then reflects the image of the document, on another mirror. After the image is reflected on this second mirror, it gets reflected again on the lens.This lens then projects the captured image on to the CCD array, through a filter.

HAND HELD SCANNERS

DRUM SCANNER

FILM SCANNER