| With the continuous improvement of printing quality and demand,the continuous development and progress of printing technology,ink layer thickness detection technology has already become one of the indispensable means of printing quality detection.The ink layer thickness directly affects the quality of printing,when the ink layer thickness value is too small will lead to smaller contrast,poor brilliance,gloss and other problems;And when the ink layer thickness value is too large,will produce serious dot increase,cause grade phenomenon,and will make the ink drying slow resulting in the back of the sticky,these problems will seriously affect the quality of printed matter,so the detection of the ink layer thickness is of great significance in the printing field.The detection method has been transformed from low efficiency and low precision eye detection to high efficiency and high precision non-contact detection.At the same time,plastic printing has also become an indispensable part of People’s Daily life,people in addition to choose from the perspective of use,more graphic printing quality as a choice of reference.Therefore,based on the existing research,it is very important to detect the thickness of ink layer on plastic film printing products.The research content of this topic is as follows:（1）Introducing the advantages and disadvantages of the traditional methods for detecting ink layer thickness,analyzes the principle of laser triangulation technology,and applies this technology to detecting ink layer thickness on plastic film combined with machine vision.According to the experimental requirements,a set of feasible detection system is designed,which includes lighting,laser emitter,image acquisition,image processing and thickness numerical calculation modules,and the experimental platform is built according to the requirements of relevant experiments.（2）At the same time,analyzing the reflection of light and the working principle of the image histogram and according to the image histogram can show intensity corresponding to pixels of this feature,designed experiment,study the effect of different incidence angles of laser reflectivity,and according to the experimental results and the test conditions,pick out the suitable for the best laser incident Angle is used to detect the thickness of the ink layer.（3）Finally,the ink layer thickness testing experiment was carried out: According to the linear laser irradiation at a certain incidence Angle on the test sample.Due to the existence of the height difference between the ink and the substrate,the laser will be offset,and the industrial camera is used to capture the laser on the sample,use Opencv to preprocess the image for blurring,sharpening,edge detection,etc.And the probabilistic Hough straight line transformation algorithm based on the vertical line is used to obtain the offset of the laser line,and finally the thickness of the ink layer is calculated according to the offset with the relevant thickness calculation formula.After calibration,the system detects ink thickness on plastic prints with an accuracy of 3μm. |
