Research Of Ultraslim Electronic Endoscopes Based On Embedded Systems

Medical electronic endoscope is a medical device that can enter the human body directly,which plays an important role in medical diagnosis.The size of the traditional electronic endoscope is relatively large,and the patients need to be anesthetized when entering their bodies,which will cause harm to them.The size of human organs has a large range of changes,and some small cavities can only be accessed by ultraslim endoscopes(The size of lens is generally smaller than 5 mm).A set of ultraslim electronic endoscope system based on 1/18 inch ultra-small CMOS image sensor is proposed in this paper.It uses USB2.0 protocol to collect and transmit data,processes and displays the image by a high-performance embedded image processor equipped with WES.At the same time,an endoscope system based on the arm processor is also designed to meet the needs in different scenarios.In the hardware system of the endoscope,the image sensing module is introduced in this paper at first.The module includes a digital image conversion method and the circuit architecture.Then the design scheme of image data acquisition module is discussed,and the image data acquisition and transmission circuit is designed based on USB2.0 controller.Finally,an embedded image processor carrier board based on COMe architecture is designed,and the size of the carrier board is controlled at 170 mm × 170 mm.In the firmware system of ultraslim endoscope,three aspects are discussed from the initialization of the image sensor,the synchronization of the image data,and the firmware writing of the USB controller.The synchronization of image data adopts Slave FIFO and GPIF.The firmware of USB controller focuses on the configuration of endpoint,and the design of synchronization and transmssion program.In addition,the use of related drivers in the WES system and the development of application software are introduced.For portable applications,a set of handheld endoscope system based on ARM A5 processor is designed in this paper too.Firstly,this section introduces the embedded Cortex-A5 processor SAMA5D31 and its related features.Then describes how to use ISI interface to access the image sensor.At last,the writing of image sensor driver under Linux system and the collection process of image data based on V4L2 framework is discussed.Functional verification and performance testing of the designed ultrathin diameter endoscope system were performed in this paper.The results showed that the system could accurately capture images with a resolution of 400 × 400 and displayed the images with 30 frames.The system had a good spatial frequency response,and the linearity of the brightness response was higher than 90%.Besides,the signal-to-noise ratio was higher than 27 dB,and the tolerance of the static image could also reach more than 110.