基于驱动时序的CCD曝光时间控制技术研究

发布时间：2018-08-24 19:23

【摘要】：近年来,随着成像光谱遥感技术的发展,光谱成像技术发挥着越来越重要的作用。光谱遥感技术的发展取决于各种技术的进步。CCD(电荷耦合器件)由于高灵敏度、低噪声和大动态范围等诸多优势已经成为光谱成像领域的核心器件。CCD探测器在亮度变化较大的环境中使用时,拍摄画面的质量严重下降。通过分析研究,在影响图像亮度的四个因素:光圈大小、入射光强度、曝光时间和信号增益中,调节曝光时间是最佳选择。但是对于不带电子快门功能的帧转移型面阵CCD成像器件,在帧频确定的情况下,曝光时间无法控制是目前使用这类CCD探测器所遇到的技术瓶颈。针对不带电子快门的CCD探测器,本文提出了两种曝光时间的控制方法:电平置位法和电荷释放法。电平置位法是通过将感光区一段时间之内的信号全都置为相同的零电平来实现的。电荷释放法是通过增加电荷释放状态,将一帧之内多余时间段的电荷迅速排放掉来有效的控制曝光时间。两种曝光时间控制方法分别基于两款不同的CCD探测器TH7888A和CCD**来实现。首先,分别介绍了两种曝光时间控制方法的具体实现,包括CCD硬件驱动电路与驱动时序逻辑设计。硬件方面,给出了合理的原理图设计方案。时序逻辑设计方面,通过VHDL语言实现了CCD正常工作需要的各种驱动时序信号,并给出了仿真结果。其次,在实验室条件下,通过搭建具体试验平台,基于本文提出的方法,进行了不同曝光时间下的试验波形与图像的采集,通过对试验结果的进一步分析,验证了所提出方法的可行性与正确性。
[Abstract]:In recent years, with the development of imaging spectral remote sensing technology, spectral imaging technology plays a more and more important role. The development of spectral remote sensing technology depends on the progress of various technologies. CCD (charge coupled device) because of its high sensitivity, Many advantages, such as low noise and large dynamic range, have become the core devices in the field of spectral imaging. Four factors affecting the brightness of the image, such as aperture size, intensity of incident light, exposure time and signal gain, are the best choice. However, for the frame transfer CCD imaging device without the electronic shutter function, when the frame frequency is determined, the exposure time can not be controlled is the technical bottleneck of using this kind of CCD detector at present. For the CCD detector without electron shutter, two kinds of exposure time control methods are proposed in this paper: level setting method and charge releasing method. The level setting method is implemented by setting all the signals in the photosensitive zone to the same zero level for a period of time. Charge release method can effectively control the exposure time by increasing the state of charge release and rapidly discharging the charge from the extra time period within a frame. Two exposure time control methods are implemented based on two different CCD detectors, TH7888A and CCD**, respectively. Firstly, the realization of two exposure time control methods is introduced, including CCD hardware driver circuit and driver timing logic design. In terms of hardware, a reasonable schematic design scheme is given. In the aspect of timing logic design, all kinds of driving timing signals of CCD are realized by VHDL language, and the simulation results are given. Secondly, under the condition of laboratory, by building a concrete test platform and based on the method proposed in this paper, the test waveform and image are collected under different exposure time, and the further analysis of the test results is made. The feasibility and correctness of the proposed method are verified.
【学位授予单位】：中国科学院研究生院(西安光学精密机械研究所)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN386.5

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