Patent ID: 8210010

Claim:
A locking device, comprising: a rotor that is rotatable within a cylinder and which includes a plurality of first tumblers and at least one second tumbler; a key having a body that is plate-shaped and insertable into the rotor; and a groove that is formed in the body that engages with and moves the plurality of first tumblers of the locking device when the key is inserted into the rotor to allow locking and unlocking operations, wherein the groove includes, at a location corresponding to a second tumbler of the locking device, a non-engagement part that does not engage with the second tumbler, such that the second tumbler allows the rotor to rotate when the non-engagement part of the key groove is aligned therewith in non-engagement, and prevents the rotor from rotating if the groove engages an engagement part of the second tumbler and moves the second tumbler.