Patent ID: 8904838

Claim:
A lock device comprising: a flat key having a control gate; and a lock cylinder including a cylinder housing, a cylinder core rotatably supported in the cylinder housing, a plurality of plate-shaped tumblers supported in the cylinder core so as to be movable radially with respect to an axis of rotation of the cylinder core, and the cylinder core having a diameter, wherein each of the plurality of the tumblers includes: two locking edges at longitudinal ends of the tumbler, the two locking edges including arc sides that are opposite from each other in a radial direction of the cylinder core, a key opening with a control cam, and a spring that applies a spring loading to the tumbler, at least one stop that limits the tumbler to travel in at least one direction of displacement to conceal an unlocking position, wherein one of the two locking edges of each of at least first one of the plurality of tumblers is at least partially pushed into a locking channel of the cylinder housing by spring loading to lock the lock cylinder when the flat key is removed, and the two locking edges of the each of the at least first one of the plurality of tumblers are moved into the unlocking position defined by the diameter of the cylinder core by the control cam guided in the control gate when the key is inserted, and wherein the two locking edges, including the arc sides, of each of at least second one of the plurality of tumblers are held within the diameter of the cylinder core by the spring loading when the flat key is removed.