| 摘要 |
<p>PURPOSE:To keep circumferential environment clean without generating atomized oil, dusts and the like by providing a negative pressure application means in least one of the two spaces formed within a cylinder by a moving element, in a drive unit used for semiconductor manufacturing equipment and the like. CONSTITUTION:A rod 2 built in a cylinder 1 is directly connected to a sample stand 3. The rod 2 is provided with a seal part 5 so as to divide space within the cylinder 1 into two such as an upper space 8a and a lower space 8b. When the first exhaust port 6 exhausts to give the upper space 8a within the cylinder 1 a negative pressure as the lower space 8b is at the atmosphere pressure, the pressure difference between them raises the sample stand 3. In order to immediately return the sample stand 3 to its original state, the second exhaust port 7 and the exhaust port 6 are given a negative pressure and the atmospheric pressure respectively at the same time. Then the lowering speed is increased.</p> |
