【正文】 n shaping circuit, shaping circuit converts the analog signals into digital signals, and then by the decoder interface circuit information translated into digital characters.Stripes, black stripes of different widths, corresponding to the length of the duration of the electrical signal is different. However, with the bar code bars and spaces corresponding electrical signal output from the photoelectric converter is generally only about 10mV, can not be used directly, thus first to send an electrical signal to the photoelectric converter output amplifier. The amplified electrical signal is still an analog electrical signal by the bar code in order to avoid defects and blemishes cause an error signal after amplification circuit need to add a shaping circuit, the analog signals into digital signals so that the puter system can accurately interpret .Pulse shaping circuit via the digital signal decoder translated into numbers, character information. It does this by identifying the start, to determine the termination character code system and scanning direction of the bar code symbol。 and by measuring the number of pulses of digital signals to determine the 0,1 and the number of empty bars. By measuring 0,1 signal duration to determine the width of bars and spaces. Thus obtained was debate read bar code symbols and empty bars and the corresponding number of width and used code system, according to the code corresponding to the coding system of rules, it will be shaped into a corresponding digital symbol, character information, by the interface circuit to the puter system for data processing and management, will plete the whole process of reading a bar code identified.A bar code is different from the width of the reflectivity of different bars and spaces, in accordance with certain encoding rules (code) was piled, and for the expression of a set of numbers or letters graphic symbol information identifier. That bar code is a set of different thickness, according to certain rules arranged spaced parallel lines graphics. Common barcode is a great difference between the reflectivity of the black bar (the bar) and white bars (the air) formed.First，Overview Barcode Barcode recognition principle (bar code recognition principle) barcode by American NTWoodland first proposed in 1949. With the growing popularity of puter applications, bar code application has been a great development. Bar code can be marked goods producer, manufacturer, product name, date of production, book classification number, starting and ending location, type, date and other information, which in many areas of modity circulation, library management, telemunications management, banking systems have been a wide range of applications.Second, the bar code identification system barcode recognition principle (bar code recognition principle) in order to read the bar code information is represented, we needed a bar code identification system, which consists of bar code scanners, amplification shaping circuit, the decoder interface circuits and puter systems part.條碼識別原理由于不同顏色的物體，其反射的可見光的波長不同，白色物體能反射各種波長的可見光，黑色物體則吸收各種波長的可見光，所以當條形碼掃描器光源發(fā)出的光經光闌及凸透鏡1后，照射到黑白相間的條形碼上時，反射光經凸透鏡2聚焦后，照射到光電轉換器上，于是光電轉換器接收到與白條和黑條相應的強弱不同的反射光信號，并轉換成相應的電信號輸出到放大整形電路，整形電路把模擬信號轉化成數字電信號，再經譯碼接口電路譯成數字字符信息。白條、黑條的寬度不同，相應的電信號持續(xù)時間長短也不同．但是，由光電轉換器輸出的與條形碼的條和空相應的電信號一般僅10mV左右，不能直接使用，因而先要將光電轉換器輸出的電信號送放大器放大．放大后的電信號仍然是一個模擬電信號，為了避免由條形碼中的疵點和污點導致錯誤信號，在放大電路后需加一整形電路，把模擬信號轉換成數字電信號，以便計算機系統(tǒng)能準確判讀。整形電路的脈沖數字信號經譯碼器譯成數字、字符信息．它通過識別起始、終止字符來判別出條形碼符號的碼制及掃描方向；通過測量脈沖數字電信號0、1的數目來判別出條和空的數目．通過測量0、1信號持續(xù)的時間來判別條和空的寬度．這樣便得到了被辯讀的條形碼符號的條和空的數目及相應的寬度和所用碼制，根據碼制所對應的編碼規(guī)則，便可將條形符號換成相應的數字、字符信息，通過接口電路送給計算機系統(tǒng)進行數據處理與管理，便完成了條形碼辨讀的全過程。條形碼是由寬度不同、反射率不同的條和空，按照一定的編碼規(guī)則（碼制）編制成的，用以表達一組數字或字母符號信息的圖形標識符．即條形碼是一組粗細不同，按照一定的規(guī)則安排間距的平行線條圖形．常見的條形碼是由反射率相差很大的黑條（簡稱條）和白條（簡稱空）組成的。一、條碼概述－條形碼識別原理（條碼識別原理） 。隨著計算機應用的不斷普及，條碼的應用得到了很大的發(fā)展。條碼可以標出商品的生產國、制造廠家、商品名稱、生產日期、圖書分類號、郵件起止地點、類別、日期等信息，因而在商品流通、圖書管理、郵電管理、銀行系統(tǒng)等許多領域都得到了廣泛的應用。二、條碼識別系統(tǒng)的組成－條形碼識別原理（條碼識別原理） 為了閱讀出條碼所代表的信息，需要一套條碼識別系統(tǒng)，它由條碼掃描器、放大整形電路、譯碼接口電路和計算機系統(tǒng)等部分組成。