PURPOSE: To correctly detect the height of a key ridge by performing the arithmetic processing which erases the drift quantity of a key in the displacement direction based on the output of the first displacement detecting means and the output of the second displacement detecting means to detect the true height of the key ridge.
CONSTITUTION: Displacement quantities detected by the first displacement detector 2 detecting the height of a key ridge 1a and the second displacement detector 3 detecting the height of a key ridge 1b when a key 1 is inserted into the key hole of a key barrel are set to the same value (x). When the key 1 is inserted offcenter by (a) to the detector 2 side, the displacement detected by the detector 2 becomes (x+a), and the displacement detected by the detector 3 becomes (x-a). The displacement quantities detected by both detectors 2, 3 become (x) by the adding processing, and the drift (a) of the key 1 is negated.
AOKI HISASHI
MIZUNO YOSHIYUKI
MIZUNO HIROMITSU
