Research On Key Technologies Of High-Definition Medical Electronic Endoscope

Medical electronic endoscopes have become widely used medical equipment. Doctors can not only observe the structures of internal organs and diagnose lesions, but also can make images displayed and stored. Currently, one of research directions of electronic endoscopes is High-Definition (HD) video, but the performance of domestic products is generally not satisfying at the moment and yet to see related products in the field of High-Definition electronic endoscopes.This paper aims to utilize the latest CMOS image sensor to achieve high-resolution imaging of medical electronic endoscopes. The study includes the development of the miniaturized camera module in the front-end, the design of the illumination system with high performance in color rendering, and the exploration of High-Definition image work-station development. According to the property and application of the system, the solution of adopting CMOS image sensor for imaging, LVDS technology for image transferring in front-end, and PCIe acquisition data card for back-end image acquisition was selected after analysis and comparison. Main work includes the following three aspects:(1) Miniaturized camera module used camera lens with wide field of view and high-resolution CMOS image sensors for photoelectric conversion. LVDS technology guarantees the long-range signal integrity for the image data stream. Reasonable design of circuits and mechanism achieve the performance of the camera module. (2) Three-chip LED illumination system was designed as the light source of electronic endoscope. Software simulation for mixing RGB light was implemented. The actual luminance flux of each LED was set according to simulation results, and finally luminous efficiency, color temperature, and property of color rendering were evaluated and analyzed. (3) The data acquisition card collected the parallel digital image data decoded from LVDS signals into the SDRAM of the computer through the PCIe interface. Then the data went to the process of demosaicing and image enhancement. The images were displayed on an LCD monitor in real time, and the images can be captured and stored in the format BMP or JPEG. Meanwhile, diagnostic method using white and multi-spectrum illumination of R, G, and B were explored preliminary.The performance of CMOS image sensor based High-Definition medical electronic endoscope system has reached the international advanced level, and with practical applications. Applications of objective lens with wide field of view and the CMOS image sensor applications make the system having a 140 degree field of view and the resolution of 1280 x 1024. With the adoption of LVDS technology, working distance of the front-end has extended up to 2 meters, and reduced the number of cable wires. Power consumption is reduced hundreds of times compared to arc-lamp light sources after utilizing LED light source. Furthermore, the configuration of light intensity of each spectrum in a light source has a greater degree of freedom. The High-Definition image workstation achieves the target of image processing and displaying in real time, and under the condition of full resolution, frame rate is 15 fps.