Click here for News Headlines
« back
When looking for a barcode scanner you will notice that there are three main technologies to choose from, but what are the differences and which should you choose? Primarily there are 3 major Barcode Scanning Technologies on the market, Laser Scanners, CCD Readers and Imagers. But what are the differences?
Laser scanners
Laser scanners work using a laser beam as the light source and typically employ either a reciprocating mirror or a rotating prism to scan the laser beam back and forth across the bar code.
A photodiode measures the intensity of the light reflected back from the light source and generates a waveform that is used to measure the widths of the bars and spaces in the bar code. In both pen readers and laser scanners, the light emitted by the reader is tuned to a specific frequency and the photodiode is designed to detect only this same frequency light. Dark bars in the bar code absorb light and white spaces reflect light so that the voltage waveform generated by the photodiode is an exact duplicate of the bar and space pattern in the barcode. This pattern is then processed and de-coded by the scanner software giving the encoded information.
Laser scanners come in three basic configurations, moving beam (single line), rastering (lines that cover an area), and omni-directional (pattern).
Laser scanners are ideal for:
Reading standard linear barcodes 
Long range and distance scanning
Scanning barcodes on an uneven surface
CCD (Charged-Coupled Device) Readers
CCD readers use an array of tiny light sensors lined up in a row in the head of the reader. Each sensor can be thought of as a single photodiode that measures the intensity of the light immediately in front of it. Each individual light sensor in the CCD reader is extremely small because there are hundreds of sensors lined up in a row.
A voltage pattern identical to the pattern in a bar code is generated in the reader by sequentially measuring the voltages across each sensor in the row. The important difference between a CCD reader and laser scanner is that the CCD reader is measuring emitted ambient light from the bar code whereas laser scanners are measuring reflected light of a specific frequency originating from the scanner itself.
CCD Scanners are ideal for:
- Reading linear barcodes and matrix codes
- Lower in cost
- Reads poor or damaged codes more accuratly
Imager (Camera-Based) Readers
Imaging scanners are the third and newest type of barcode reader currently available. They use a small video camera to capture an image of a barcode. The reader then uses sophisticated digital image processing techniques to decode the barcode. Video cameras use the same CCD technology as in a CCD barcode reader except that instead of having a single row of sensors, a video camera has hundreds of rows of sensors arranged in a two dimensional array so that they can generate an image.
CCD Scanners are ideal for:
- Imagers can read linear barcode, Matrix codes, 2d codes and caputure signatures or images
- Will read most symbologies
- Ability to capture more than just barcode information
|
|
|
|
When deciding on which technology suites your needs best you need ask the following questions:
- The symbology you wish to read; 1D codes, 2D Codes, Image caputure etc
- Your average scanning range; millimetres, centimetres or further
- Your scanning environment; indoors, outdoors, poor lighting etc
Once you have decided which type of scanning technology is best suited for your application you then need to decide which scanner.
If you have any questions on which technology would best your needs, call our team on 01527 839010 who would be happy to advise on systems and technology available.
Date of news item upload : Mon Aug 20 2007
« back
|
