What malfunction occurs in the Proximity Sensor because of the influence of a surrounding metal?

The sensing distance is extended, and faulty reset is resulted.

Description

The sensing distance is extended

ON point (ON2) when there is a surrounding metal is further than ON point (ON1) when there is no surrounding metal.

Faulty reset is resulted

There is no OFF point because it lowers more than OFF judgment level even when the sensing object is far and the oscillation level is high when there is a surrounding metal.