Study Of Image Acquisition System On Ccd

As the deep development of information technology, our life, productivity even the mode of thinking have changed impressively. And as an indispensable port of the information process, image acquisition plays an important role in different areas. Charge Couple Device (CCD) is a kind of fully developed image sensor, and its related applications are widely used in developed countries, while it is still in a highly developing stage in our country. This study originates from the medical device’Cornea Pattern Acquisition Device’, whose image acquisition front end introduces the CCD image sensor to implement the image acquisition for people’s cornea pattern information. This information is the base of the doctor’s diagnosis of patient’s cornea. This paper studies the CCD image acquisition part of the device, and serves as a knowledge reserve for its further development.For the above purpose, the main study made for the image acquisition system in this paper is as follow:This paper makes a deep study of the CCD ICX424AL drive timings, and introduces a MCU, a CPLD and a CCD signal processor to design the drive timings. The CCD vertical drive timing generator circuit designed in CPLD is described by Verilog HDL. Then, a simulator and a programmer of the Quartus II are used to implement function simulation and device program for the circuit. At last, a digital oscilloscope is used to test the actual drive waveform. This paper makes a deep study of the AD9949A’s AFE, timing core and the registers accessing methods. The AD9949A not only makes a preprocessing and digitalization process for the CCD output analog signal, but also provides the horizontal drive timing and reset clock for the ICX424AL by programming its timing core registers. As a result, the system becomes more integrate. The above two drive timings are synchronized by the vertical and horizontal synchronization signal which are provided by the MCU STM32F103C8T6. Because this system needs four different voltage sources, the switch power converters and a LDO power supply are introduced to design the system power module. The circuit introduces a video operation amplifier to condition the CCD output analog signal. Then, the analog signal is transmitted to the AD9949A for sample, gain adjustment and the last digitization process.The EDA tool Altium Designer6.9is introduced to design the hardware circuit and PCB. According to the device machine structure, the hardware system is composed of three PCB which are the main board, the CCD board and the interconnection board. The MCU control program is programmed under the uVision4IDE. After debugging the system hardware circuit and the software program, the CCD drive timings, the AFE clock used to process the CCD signal and the output CCD analog signal are tested respectively.