摘要 |
A closed-type cassette is mounted on a cassette stand disposed in a working region at a position corresponding to an opening formed in a wall separating the working region from a loading region. When the cassette is mounted on the cassette stand, a detecting device gives a signal to that effect to a controller. Then, the controller closes a valve to interrupt nitrogen gas supply into the loading region. A lid of the cassette is opened 20 to 30 sec after the interruption of nitrogen gas supply into the loading region and, then, nitrogen gas supply is resumed. The pressure difference between the loading region and the interior of the cassette is decreased by interrupting nitrogen gas supply into the loading region, so that the lid can be easily opened.
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