角膜地形图仪中基于USB2.0传输方式的成像系统设计与实现

Design and Implementation of Image System Based on USB2.0 Transmission Mode in Corneal Topography

摘要: 通过对USB2.0及1394接口数据传输的优缺点比较，结合角膜地形图仪图像采集传输的要求，设计了面阵CCD的驱动及USB2.0数据采集传输系统。在该系统中，选用Sony公司IXC445ALA面阵CCD作为系统图像采集的传感器，根据ICX445ALA的驱动时序要求，利用AD模数转换和CPLD的时序框架及单片机时序控制，实现了驱动电路的设计。针对单片机的USB2.0固件驱动，完成了USB2.0的数据输出。通过控制单片机的I/O口，实现了LED背光源的开闭、左右眼的自动判别及角膜图像的获取。最终检测表明，所获得的角膜图像清晰，USB2.0数据传输快速稳定，单片机辅助功能工作正常。较好地实现了角膜地形图仪中图像采集传输的要求。

Abstract: Through comparing the data transmission advantages and disadvantages of USB2.0 and 1394 in-terface, and combining the data acquisition and transmission requirement of corneal topography, the array CCD driver and USB2.0 data acquisition and transmission system was designed. In the system, Sony ICX445ALA array CCD was chosen as image sensor, according to the ICX445ALA drive timing characters requirements, using CPLD and AD timing framework and MCU timing control, the drivering circuit design was realized. According to MCU’s USB2.0 firmware driver, USB2.0 data output was completed. By controlling the I/O port of the MCU, the open and close of the LED backlight, the automatic discrimination of the left and right eyes and the acquisition of the corneal image were realized. The final test shows that the obtained corneal image is clear; the USB2.0 data transmission is fast and stable. The MCU auxiliary function is effective. It can achieve the requirements of image acquisition and transmission well in corneal topography.