Designing and implementing a miniature CMOS imaging system with USB interface

Abstract

Although CMOS cameras with USB interface are popular, their sizes are not small enough and working lengths are not that long enough when used as industrial endoscope. Here we present a small-sized image acquisition system for high-definition industrial electronic endoscope based on USB2.0 high-speed controller, which is composed of a 1/6 inch CMOS image sensor with resolution of 1 Megapixels. Signals from the CMOS image sensor are put into computer through the USB interface using the slave FIFO mode for processing, storage and display. LVDS technology is used for image data stream transmission between the sensor and USB controller to realize a long working distance, high signal integrity and low noise system. The maximum pixel clock runs at 48MHz to support for 30 fps for QSXGA mode or15 fps for SXGA mode and the data transmission rate can reach 36 megabytes per second. The imaging system is simple in structure, low-power, low-cost and easy to control. Based on multi-thread technology, the software system which realizes the function of automatic exposure, automatic gain, and AVI video recording is also designed.