CYLINDER LOCK

PROBLEM TO BE SOLVED: To make unauthorized duplication of a key difficult by changing a shape of a driven pin-side code portion and that of a key-side code portion without incorporating new mechanism or component. SOLUTION: An inverted truncated cone-shaped cavity is formed in the top surface of the truncated cone-shaped inner end of the driven pin, so as to have the truncated cone-shaped inner end and the inverted truncated cone-shaped cavity served as the driven pin-side code portion. An inverted truncated cone-shaped recess of the key is formed in such a shape that an inner bottom surface is inclined with respect to the thickness-direction center line of the key while a round head-shaped protrusion is formed on the central portion of the inner bottom surface of the inverted truncated cone-shaped recess, so as to have the inverted truncated cone-shaped recess and the round head-shaped protrusion served as the key-side code portion. A difference is set at the depth of the inner bottom surface of the inverted truncated cone-shaped cavity. When a bottom surface of a truncated cone-shaped cavity abuts on the top of the round head-shaped protrusion, and when a portion, where the driven pin and a driving pin abut on each other, reaches the top of a shear line, gaps are to be left between an inner peripheral surface of the inverted truncated cone-shaped recess and an outer peripheral surface of the truncated cone-shaped inner end, and also between an outer peripheral surface of the round head-shaped protrusion and an inner peripheral surface of the inverted truncated cone-shaped cavity. COPYRIGHT: (C)2010,JPO&INPIT