Pen-type bar code scanners
Pen-type bar code scanners has a light-weight source and photo diode that area unit placed next to every alternative within the tip of a pen or wand. For bar code scanning, the person holding the pen must move the tip of it across the bars at a comparatively uniform speed. The photo diode measures the intensity of lightweight reflected back from the light supply because the tip crosses every bar and area within the written code. The photo diode generates a waveform that is accustomed live the widths of the bars and areas within the Universal Product Code.
Laser bar code scanners
The way pen kind readers work laser scanners mostly manufactured works like that except that they use an irradiation because the source of illumination and generally use either a reciprocity mirror or a rotating prism to scan the irradiation back and forth across the Universal Product Code. As with the pen type reader, a photo-diode is used to live the intensity of the sunshine reflected back from the Universal Product Code. In both pen readers and optical maser scanners made by Barcode Scanner sellers in Kolkata, the light emitted by the reader is quickly varied in brightness with an information pattern and also the photo-diode receive electronic equipment is intended to sight solely signals with a similar modulated pattern.
C-C-D readers (LED scanners)
C-C-D readers use an array of lots of small lightweight sensors lined up in an exceedingly row within the head of the reader. Each detector measures the intensity of the lightweight right away before of it. Each individual lightweight detector in the C-C-D reader is very tiny and since there are a unit many sensors lined up in an exceedingly row, a voltage pattern identical to the pattern in an exceedingly Universal Product Code is generated within the reader by sequentially measure the voltages across every detector within the row. The important distinction between a C-C-D reader and a pen or optical maser scanner is that the C-C-D reader is measure emitted close lightweight from the bar code whereas pen or optical maser scanners area unit measure mirrored lightweight of a selected frequency generated from the scanner.
2-D image scanners
2-D image bar code scanners are the most advanced kind of Universal Product Code reader. They use a camera and image processing techniques to decipher the bar code.
small video cameras with C-C-D technology are used by Video camera readers as in an exceedingly C-C-D Universal Product Code reader except that rather than having one row of sensors, a video camera has hundreds of rows of sensors organized in an exceedingly 2 dimensional array in order that they'll generate a picture.
All directional bar code scanners
All directional scanning has a couple of straight or parallel lines for scanning of variable directions in the variety of a starburst, a Lissajous pattern, or other multi angle arrangement area unit projected at the image and one or additional of them can be able to cross all of the symbol's bars and areas, no matter what the orientation.
All directional scanners nearly all use an optical maser. Unlike the easier single-line optical maser scanners, they produce a pattern of beams in variable orientations permitting them to scan bar codes bestowed to it at completely different angles. Most of them use a single rotating polygonal mirror and a meeting of many mounted mirrors to come up with their complicated scan patterns.
