To stop falling with a shelter member without affecting a breathing flow by providing an exhaust guide plate that projects in a rising direction in an outer direction from the low end part of the air outlet of an airflow for cooling an internal circuit at the upper side of an enclosure body, and providing the shelter member that is extended in the side direction of the low end part and is directed toward an upper direction.
A dropped screw 41 falls onto an exhaust guide plate 52, bounces, rolls, and falls on the exhaust guide plate 52 as shown by an arrow F, hits against and is stopped by a shelter member 53, and cannot move any further, thus preventing the screw 41 from being further engaged to the inside of an enclosure body 3 since the position of the shelter member 53 is set to the inner surface side than the rear surface of the enclosure body 3 as compared with space being released onto the exhaust guide plate 52 and a flat surface is formed at the low end part. When a screwdriver 42 drops with its tip side facing down, the tip side hits against the exhaust guide plate 52, falls in a direction marked by an arrow G while bouncing, slides down as shown by H and hits against the shelter member 53 as shown by a solid line, and hence cannot move any further and stops.
HORIKOSHI OSAMU
SAITO MASAHIKO
