条形码的硬件技术（国外英文资料）.docVIP

条形码的硬件技术（国外英文资料） The hardware technology of barcodes The 1992-08-07 One, photoelectric scanner In the bar code technology, photoelectric scanner is one of the main hardware equipment, bar code data automatic collection, photoelectric signal conversion are accomplished by photoelectric scanner. The photoelectric scanner is usually composed of two parts of the optical system and the circuit system, and the optical system mainly consists of light source, lens and slit. The circuit is composed of photodiode detectors, amplifiers, and wave shaping machines. Its working principle is the use of an optical system reads the bar code symbol, by a photoelectric converter converts light signals into electrical signals, and through the circuit system for signal amplification and plastic, finally in binary pulse signal output to the decoder. Photoelectric scanners are usually a kind of active system. A beam of light from the scanner itself to the symbol, then measured the reflectivity of point, an empty (white) than the reflected light bar (black), so from that point reflectivity can distinguish the size of the article and empty. The scanner is concentrated in light and received in two kinds. The beam of light is illuminated by a strictly controlled focus beam, which is the resolution of the scanner. And to control the reflected light is not very strict, than loose some irradiation light, often call this kind of light source concentrated exposure. Receive condenser is strictly control the reflected light, through a window in the receiver to get a spot on imaging and the light spot diameter of the scanner resolution, in this way, or the irradiator emit light or strong light irradiation to sign on the outside world, the sensing area is after a scan bar code symbols for focusing spot. The light source is usually called a spotlight receiver. Symbol of reflected light directly by photodiode detector, and generate a and receives the light intensity is proportional to the small current