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US 5,970,761 AGranted
Lock system with key trapping
AssigneeInternational Security Products, Inc.
InventorCharles W. Eden, Jr.
Life of this patent
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AssigneeInternational Security Products, Inc.
InventorCharles W. Eden, Jr.
Estimating the term…
A novel lock system utilizes a cylinder lock and a companion key with a projection extending from one side thereof to improve security. The cylinder lock comprises a shell, a core which is rotatably mounted within the shell and a plurality of pin tumbler stacks normally prevent movement between the shell member and the core. Shear lines are defined between the shell and the core, and also within each tumbler stack. The core also includes an outer surface, a longitudinal keyway and a cut-out which is normally offset from, but alignable with, at least one of the tumbler stacks. A plate member is disposed within the cut-out for movement between a first position, wherein the plate member acts as an extension of the core surface to prevent a tumbler stack from entering the cut-out and a second position, wherein the plate member does not prevent a tumbler stack from entering the cut-out. Upon insertion of an authorized key, the key bitting will appropriately align the tumbler shear lines with the shell/core shear line, and the key projection will urge the plate from the second position to the first position and thereby permit the core to rotate to an unlocked position. Upon insertion of a properly bitted key which does not possess an appropriate key projection, however, only partial core rotation is permitted whereupon a tumbler stack enters the cut-out to thereby render the lock inoperable and trap the unauthorized key within the keyway.
A key blank for a key intended for use in cooperation with a cylinder lock having a rotatable core, the core of the lock including a keyway which extends inwardly from a first end of the core, the keyway having a pair of opposite sides which define a keyway cross-sectional profile, the core also defining a cut-out which extends to the keyway through one of the sides of the keyway in a region displaced from the first end of the core, the cylinder lock further having a plate movably mounted within the cut-out, the plate having a cam follower projection which extends into the keyway intermediate the ends thereof, said key blank comprising:
A key blank for a key intended for use with a cooperating cylinder lock having a relatively movable member with a cam follower projection which extends into the keyway of the cylinder lock through a side thereof, said key blank comprising:
A key blank, said key blank being configured for use as a key for a cooperating cylinder lock after bitting in accordance with the lock combination, the cylinder lock having a keyway with an irregular cross-section, said key blank comprising:
Dependencies are inferred from the claim text.