| 摘要 |
<p>The arrangement utilises two parallel masts which are fixed to a foot lever at the base and to two horizontal parallel bars at the top. At the base, between the masts, is a motor with a drum around which a cable passes and travels over pulleys on the bars to pulleys on a scissor jack assembly. This jack assembly is fixed to a chassis which travels along the masts driven by a chain from a motor at the base of the masts. This allows the height of the camera to be controlled. The chassis supports a second chassis on which a motor drives an endless screw to control the extension of the jack assembly to position the camera.</p> |
