PURPOSE: To surely prevent illegal unlocking by providing a key made of a magnetic material, a magnetic substance member provided around the key hole of a key barrel, and a means detecting the magnetic characteristic of a magnetic circuit changed in response to the key ridge shape of the key.
CONSTITUTION: When a key 1 is inserted into the key hole 2a of a key barrel 2, a magnetic circuit is formed via a gap between the key 1 and a magnetic substance 3. When the key 1 is inserted into the key hole 2a in sequence, the magnetic circuit is changed in response to the change of the shapes of key ridges 1a, 1b. The inductance of an electric coil 4 is measured by an electric circuit, and electrical signals in response to the key ridges 1a, 1b are inputted to a judging circuit. The judging circuit compares these electrical signals with the previously stored normal electrical signals corresponding to the inductance of the key 1, it operates an unlocking system if they coincide, and the key barrel 2 is rotated together with the key 1 for unlocking.
| WO/1995/013444 | LOCK |
| WO/2001/075253 | LOCK WITH A CENTER GAP SIDEBAR |
| WO/2009/147677 | CYLINDER PROTECTIVE SYSTEM |
AOKI HISASHI
MIZUNO YOSHIYUKI
MIZUNO HIROMITSU
