Microcontroller-based Auto-focus Technology Research And Applications

In this paper we study an auto-focusing system based on microprocessor and CMOS image sensor. The method is as follows:When the video signals from CMOS image sensor pass through a high-pass analog filter,the microprocessor samples and processes them and then judge whether the lens is in focus .If the lens is not well focused,the microprocessor will control the lens to be in focus by moving the stepping motor. The method based on single-chip processor can get all functions of auto-focusing technique avoiding complicated calculations. The whole system is low power,rapid focusing,and can be widely used. Here the key technique of the system is discussed and the result of the experiment is given.In this paper,the different demands of focusing on different environment and on different objects are discussed. The different effects of focusing on different evaluation functions and on different filter frequencies are compared experimentally. After analyzing the factors that influence the focusing speed and the precision,the paper put forward the improving measures.At last an application system is introduced.