Design And Realizatation Of Depth-of-field Detection System For Contact Image Sensor

Contact Image Sensor (CIS) is a kind of sensor that can scan imageinformation, which is applied in many fields. In recent years, it develops rapidlyespecially in financial equipment field. Financial equipment needs fast speed inpaper (money) skip, so in order to let both new and old paper money pass fluently,there needs a certain space between CIS and paper money, in which CIS scan all thepaper money clearly. The function of scanning image through different space iscalled CIS’s Depth of Focus (DOF). In order to test and analyze the DOF of CIS, itis particularly important to design and develop the DOF detection system.CIS’s Depth of Focus (DOF) is mainly analyzed from three aspects in thethesis: the first is the relation between CIS’s output when scanning white charts andthe measuring position; the second is the relation between CIS’s output uniformitywhen scanning white charts and the measuring position; the third is the relationbetween CIS’s output definition when scanning black-and-white charts and themeasuring position.This thesis focuses on researching CIS’s DOF for which it designs and realizesdetection system. The thesis firstly introduces the domestic and overseasdevelopment status and existing problems about the related technologies of DOFdetection system. Then as for the function components of this system: its operationinterface is designed with Labview, which realizes the function of data storage,parameter call, and communication with lower computer, etc; it designs and realizescommunication module between FPGA and PLC and detection module for CIS’sperformance test; in mechanical control part, it carries out PLC control module; inmechanical structure part, through stepper motor and air cylinder, it realizes thefunction of DOF position adjustment and test charts adjustment. In order to verifythe feasibility and reliability of the system, the article finally discusses thecomprehensive test of it with satisfactory result achieved. With the advantages ofsimple operation, accurate and efficient measurement, etc, the system has highpractical value in actual production.