Study On Mobile Phone Shell Inside And Outside Surface Quality Inspection Based On Fringe Projection And Fringe Reflection Technologies

With the advence of the mobile Internet era, the smartphone market expand rapidly, leading to the more attention on the quality control of smartphone production. Therefore, this paper focus on the study on mobile phone shell surface based on fringe projection and fringe reflection technologies. In order to achieve high accuracy and rapid detection for various kinds of cellphone shell, firstly, this parper analyses the basic principle and error factors of fringe projection and fringe reflection technologies. Then, for applying 3D measurement method to different type cellphone shell, parper deeply study to the reflectivity on cellphone shell. Thirdly, to improve speed and accuracy of measurement, an improved integral algorithm is proposed, which is more efficient. Finally, the experiment on mobile phone shell surface quality inspection have been done in the composite system of fringe projection and fringe reflection technologies. The main contents are exhibited as follows:In this parper, Nayar model is adopted to establish the reflection model of cellphone shell. On the basis of Nayar model, the impact of specular reflectance in fringe projection and fringe reflection technologies are analyzed. The results of the analysis provides a guidance for matching method of measurement in different types cellphone shell.In order to improve the precision and speed of the Southwell integral algorithm, in a combination of Taylor high-order integral algorithm and iterative compensation integral algorithm, the Taylor high order iterative integral algorithm method is put forward. Because of the higher order Taylor polynomial is used to construct integral equation, the integral height has a smaller truncation errors, which would reduce the number of iterations and save the reconstruction time.During the measurement of low reflectivity objects, the fringe projection technology and fringe reflection technology are difficult to achieve higher accuracy separately measurement, in paper, we presents a composite iterative algorithm, Which can reserve the height measurement advantage of fringe projection, coupled with the gradient measurement sensitivity of fringe reflection technique. The new algorithm combines the advantage of each measuring technique, and the superiority of the algorithm was confirmed in the simulation and experiment.Finally, the experiment of mobile phone shell inside and outside surface defect detection by the composite system has been carried out. In this part, the paper not only introduces the defect detection method, but also analyses the measuring precision. The accuracy of measurement of the surface outside reach to 0.14 microns, and the surface inside is 33 microns, which can meet the requirements of industrial detection.