Research Of Acquisition Technology For Image Data On High-speed Area Array CCD

At present, image acquisition and processing technology has been widely used in industrial control, geologic disaster forecast, daily consumer electronics, aerospace, medical instrument, military defense and other fields. Because of the excellent imaging performance of CCD, CCD technology has become the integrated application technology of the optics, electronics, precision machinery and computer application technology. Combining the CCD application technology, embedded applications, computer image processing technology with atomic spectrometry, it can be more efficient in the sample material for qualitative analysis and quantitative detection, such as the trace elements, metals and other rare elements. Therefore, the research of key technologies of image data acquisition system basedd on high-speed area array CCD is of value.With the increasing development of CCD application technology, the image acquisition and processing technology is demanded more and more, especially in real-time, complex processing, major operations volume, low power, small size, portability and development costs and so on.This image acquisition system is designed to put forward three demands: on the one hand, relatively large amount of data communications, requests the main control units that have higher processing speed, and image data can be quickly and timely processed; on the other hand, in order to obtain high quality images, it requests conditioning of the image signal, effectively eliminate the noise and the use of high-performance analog-digital conversion circuit; Furthermore, image acquisition system must be flexible and generic interface which has higher data transfer rate.In this paper, contrary to ICX205AL area array CCD, analysis key technologies of image data acquisition system basedd on high-speed area array CCD and conduct the following studies:1. Design drive of area array CCD based on FPGAThrough searching a large number of information about image sensors,this paper analysis area array CCD of the structure and working principle. Driven approach often was adopted in the past, including directly digital drive, EPROM-driven, MCU-driven, there exist a series of problems,for instance, emphasis on hardware implementation, debugging problems, poor flexibility, resource waste, low frequency limit.In this paper, Contrary to Sony company's ICX205AL area array CCD, do a detailed analysis of drive.In the Quartus II platform, use the Verilog HDL language based on finite state machine to design its drive circuit and drive scheme, as well as the timing simulation.2. Design AFE of Image acquisition systemIn the image acquisition system, AFE, following the CCD drive, is another problem demanding prompt solutinon,its design has a great impact on the visual effect of the image. Analysis the output signal of the ICX205AL, design signal conditioning modules,including filtering, amplification, CDS correlated double sampling. Meanwhile, providing the control signal which is matched with the CCD drive , is to ensure the accuracy of the image signal sampling,and follow up basis of processing of image data.3. A/D acquisition and buffer circuitIf using a SCM as the main control unit in the whole system can no longer meet the requirements, we use the ARM processor which has higher performance, but it has the problem between the high speed and low speed. The overall design of the image acquisition is established,studying ping-pong mechanism of the FPGA soft FIFO and data reading means of S3C2410 DMA to solve the problem on match of the image data acquisition speed and high-speed of control unit ,to ensure the continuity of image data acquisition.4. Design data transmission interfaceAs the large area array CCD have stringent requirements of real-time and high data transmission rate,while the speed of traditional serial port is very low,so it can't meet the requirements,though the parallel can overcome this, its transmission distance is short, connecting is so difficult that it does not meet the requirements about flexibility. After transplantation of embedded Linux system, this paper develops USB device drive in the embedded platform, to communicate with the host. the subject of transfer is high transfer rate, and its development time and cost is low.Combinating of embedded technology, large scale integrated circuit with CCD,we analysis key technologies of image data acquisition system basedd on high-speed area array CCD.Resolve the problem of CCD drive, signal conditioning, speed match of acquisition system and high-speed data transmission.Acquisition system has advantages on high-speed, low power, small size , development of flexibility and scalability.For the development of the full spectrum ICP-AES of Beijing KECHUANG HAIGUANG INSTRUMENT CO.,LTD,it has important reference value,as well as image acquisition based on the area array CCD.