Research On Automatic Focus And Centering System Of Small Lens Based On Image Processing

With the wide application of camera module in various industries,the market demand for camera module increases sharply.In order to obtain high-quality imaging and improve the competitiveness of module enterprises in the industry,the efficient and rapid production of qualified camera module composition is an urgent problem to be solved for the camera module manufacturers.This topic comes from the research on the auxiliary focusing and centering system of the camera module in the assembly process of a certain enterprise,which mainly includes the following research contents:1.Based on the imaging characteristics of large wide-angle and small lens,a method of wrapping target image acquisition is proposed,which can perfectly collect the imaging information of each field of view.The center of gravity detection method is adopted to determine the center of the current lens.Through experimental data analysis,the center of gravity method is not only fast,but also very high positioning accurate,which can reach pixel level.It provides accurate small lens imaging center coordinates for centering,ensures no deviation between lens imaging center and pixel center,and maximizes imaging.2.Based on the selection of focus window,focus function evaluation,focus optimization algorithm.After comparison,a non-uniform dynamic windowing method is selected to determine the sampling area through the non-uniform windowing method after the separation of background and effective area.The Tenengrad method is determined as the calculation method of image sharpness,which has high steepness,strong monotonicity and reasonable steepness width.Since the imaging environment used in this paper is the same product for a long time,it is considered that the focusing curve obtained by statistics is applicable to most products according to the optical physical invariance.Therefore,based on this feature,an adaptive jump autofocus method is proposed,which can quickly jump out of the coarse focus area and into the vicinity of the fine focus area.3.Based on the study of the mechanical structure of the existing system,the STM32 motor drive system is determined.It can not only satisfy the movement of the centering system in the horizontal direction,but also make high precision adjustment in the horizontal direction,which ensures the successful application of the autofocus algorithm.Through the above research content,the focusing and centering system studied in this system provides a quick adjustment method for the module production with fixed focal length,and guarantees the production efficiency and product quality of the camera.