Patent attributes
In a state of mapping sensors having been advanced into a carrier by a sensor advance/withdraw mover, a sensor lifting and lowering device moves the mapping sensors up and down. With this movement, the mapping sensors detect presence or absence of substrates in a horizontal direction crossing a fore-and-aft direction in which the substrates are moved into and out of the carrier, and a height sensor detects heights of the mapping sensors. Consequently, substrate heights are detected in two different locations in the fore-and-aft direction. Based on the substrate heights, a substrate condition acquiring unit acquires a tilt of each substrate relative to the horizontal in the fore-and-aft direction. The tilt of each substrate inside the carrier is acquired in advance, thereby to be able to prevent substrate damage due to contact between a hand of a substrate transport mechanism and the substrates.
