| 摘要 |
PURPOSE:To provide the high degree of vacuum in a short time, by a method wherein, after the vacuum of an object space is drawn by using a tank, the degree of vacuum in the space is increased with the aid of a vacuum pump. CONSTITUTION:A cavity 1, a tank 4, and a vacuum pump 2 are connected together through a 3-position electromagnetic valve 3c to form a vacuum drawing circuit. First, a vacuum in the tank 4 is drawn with the aid of the vacuum pump 2, and with the electromagnetic valve 3c switched, a vacuum in the cavity 1 is momentarily drawn. Secondly, with the electromagnetic valve 3c switched, the degree of vacuum in the cavity 1 is increased with the aid of the vacuum pump 2. This constitution enables provision of the high degree of vacuum in a short time without using a so large-scale vacuum pump and tank.
|
