| 摘要 |
<p>The projection optics for sound film is such that the film is moved through the gate at a constant spee, a scanning prism providing the light gate. The prism is oscillated at the end of a control arm whose free end is held against a rotating cam by a spring. The can is so shaped so that the prism only rotates over a half revolution in each direction and is then returned to the starting position. This provides a flicker-free and clearer picture.</p> |
