基于正时带的帘幕式快门设计与精度分析

考虑帘幕式快门的曝光精度和面阵CCD相机的结构尺寸,利用正时带在高速运动中能够保证高精度传动的特点,设计了以正时带为快门帘幕,以正时带轮为快门辊轴的新型单帘式焦平面快门。分析了影响快门曝光精度的主要因素,利用系统误差合成法建立了快门曝光精度的数学模型。利用齿轮综合误差组评价了驱动机构的传动误差,通过分析正时带的传动机理建立了多边形效应的几何模型,并计算了多边形效应对速度精度的影响。在接入快门负载的情况下测试得到了快门辊轴的稳速精度,并利用高斯法计算得到了快门的曝光精度0.067。最后,利用光电法测试了幅面上均匀五点的有效曝光时间,测量结果显示幅面内快门的曝光精度达到0.056,可实现宽目标照度范围航空摄影的曝光。

Design and precision analyzed of new curtain type shutter based on timing belt

In consideration of the exposure precision of a curtain shutter and the dimension of a camera, a new focus-plane single curtain type shutter was designed by using a timing belt with high transmission accuracy as the curtain of shutter and a belt wheel as the roll shaft. The main reason effecting the exposure precision was analyzed, and a mathematic model was created by the system error synthesis method. Then, the series of gear-composited errors was used to evaluate the transmission errors of a driving mechanism. Furthermore, the geometric model of the polygonal effect was established by analysis of the transmission mechanism of the timing belt, and the influence of polygonal effect on the rate errors was calculated. After testing on the shutter,the speed stability of the roll shaft is obtained and the exposure precision achieves 0.067 according to the Gaussian processes. The exposure time at 5 positions on a frame was tested by the photoelectric method,and the result shows that exposure precision in the frame achieves by 0.056, which demonstrates that this shutter can exposure on the aerial photographing of large range illuminance.