Clean unit, clean unit operating mode and connected clean unit

It has a dust filter having a blowing force on the upper surface of the working chamber, the clean unit capable of maintaining a clean environment and an inlet of the ventilation hole and the dust filter provided in the wall of the working chamber with airtightness the external gas flow path directly to the feedback gas flow path connecting, or not through the dust particles, and connected via the gas molecules pass through the partition wall, the flow velocity vector and the external gas in the gas flowing through the feedback gas flow path on either side of the partition and flow velocity vector of the gas flowing through the flow path is set to be equal to each other.