A design on a control method of a new type of focal plane shutter

In order to ensure appropriate exposure time, and no exposure while electric charge is transferring after taking a photograph, it is necessary to have the shutter mechanism cooperate with CCD for area CCD aerial cameras. The ground object illumination has a wide range which is from 4000Lx to 100000Lx, so a shutter which is high efficient and a continuous stepless adjustment are also required. This paper introduces the fundamental principle, structural design and control procedure about this new focal plane shutter. Under the control of DSP, the velocity of shutter curtain governed by the shutter motor can be not only precisely controlled, but also the durability and the reliability are increased. The experiment results have shown that this new shutter has the higher stability of movement, long life span with more than 105 operating times, a wide range of exposure time from1/ 50s to 1/ 320s(depending on the slit width) and the exposure error is less than 10%. With the CCD gain adjustment, the performance of this shutter is fully satisfied with the requirements of area CCD aerial cameras.