Each sensor determines the brightness of the light directly in front of it. In both pen readers and laser scanners, the reader's light is quickly modulated with a data pattern, and the photodiode receive circuitry is configured to detect only signals with the same modulated pattern.ĬCD monitors (also known as LED scanners)ĬCD readers use an array of hundreds of tiny light sensors lined up in a row in the reader's head. As with the pen-type reader, a photodiode is used to determine the intensity of light reflected by the barcode. Scanning back and forth over the barcode with the laser beam. The scanner decodes this waveform in a similar fashion to how Morse code dots and dashes are deciphered. Because dark bars absorb light and white spaces reflect it, the voltage waveform created by the photodiode is a representation of the barcode's bar and space pattern. The photodiode creates a waveform that is utilized to determine the barcode's bar and spacing widths. As the tip passes each bar and space in the printed code, the photodiode detects the intensity of the light reflected back from the light source. To read a barcode, the individual holding the pen must move the tip at a roughly regular pace over the bars. Pen-style readers are made up of a light source and a photodiode that are attached to the tip of a pen. Additionally, virtually all barcode readers have decoding circuitry that analyzes the picture data given by the sensor and outputs the barcode's information to the scanner's output port. As is the case with a flatbed scanner, it is composed of a light source, a lens, and a light sensor for converting optical impulses to electrical signals. (or barcode scanner) is an optical scanner that is capable of reading printed barcodes, decoding the data contained inside the barcode, and transmitting the data to a computer.
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