新型牙科X线机的设计及样机研制

摘要

Objective Using new electronic technique and component, to develop a set of high frequency direct-current dental X-ray machine, thus to realize high performance of dental X-ray machine. Methods IGBT high frequency inverter, real-time sampling, PWM for the closed-loop control of the tube current and anode high voltage, microcomputer for the precious control, multi-segment compensation for the effect of cathode space electric csharge, combined X-ray tube are introduced to manufacture ifve sets of dental X-ray machine. TL494 is utilized to construct main circuit of feedforward control of X-ray tube current, based on chosing the compensation factor depended on anode voltage range for cathode space electric charge. Results Preliminary results showed that these control methods and circuit devices are effective. The machine has some good features such as, all high voltage parts are inside the tube, the error of tube voltage was less than 1%, the error of exposure time was less than 3%, the photos of the teeth marrow can be clearly seen. Conclusion The sample machine could meet the requirements of medical application.%目的采用新的电子技术和元器件，研制高频直流牙科X线机，实现牙科X线机高性能化。方法利用高频逆变元件，实时采样、脉宽调制确保对阳极高压和管电流的闭环控制；采用TL494构建管电流前馈控制策略，根据管电压范围段进行分段（非线性）补偿阴极空间电荷效应。结果初步试验表明，该控制方法及电路装置效果良好，实现了外部无高压，且加在X线发射管上的电压波动在1%以内，曝光时间误差在3%以内，拍摄的照片可以清晰显示出牙髓腔及周围组织。结论该样机完全可满足临床牙科透视要求。