US 4,936,896 AGranted

Device for confirming whether a lock is locked or unlocked

AssigneeHiroshi Hasegawa

InventorJitsuho Takatsuka

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Abstract

A device for confirming whether a lock is locked or unlocked in which a display magnet consisting of a sheet- or plate-like permanent magnet is rotatably disposed within a key head. Two magnet pairs, each consisting of a first drive magnet, and a second drive magnet are located at angular positions, respectively, on the front end face of a cylinder lock at opposite sides, respectively, of an intermediate angular position within a range of rotation of a key for locking and unlocking the cylinder lock. The direction of magnetization of one magnet pair is opposite to that of the other magnet pair. In response to the rotation of the key for locking or unlocking the cylinder lock, one, and the other, magnet pair imparts magnetic forces through a pair of magnetic induction plates disposed within the key head to the display magnet from different directions so that when the cylinder lock is locked or unlocked, the display magnet is forced to rotate in one or other direction to a predetermined angular position and is securely maintained at this position by the attraction between the display magnet and the magnetic induction plates.

Claims14

Dependent claims

A device for confirming whether a lock is locked or unlocked, comprising:

a key having a longitudinal axis and a head, said head including a permanent magnet pivotably mounted in said head, and at least one induction plate mounted in said head, said induction plate having an abutment portion disposed within the path of rotation of said permanent magnet;
a lock capable of being locked and unlocked by rotation of said key about said longitudinal axis within said lock, said lock having a front face;
at least one first and at least one second driving magnet connected to said lock and disposed in spaced relation to each other proximate said front face, each said first driving magnet also being disposed in opposing relationship to a respective said second driving magnet about a reference line, the reference line being normal to the axis of rotation of said key within said lock;
each said first driving magnet having a polarity opposite each said second driving magnet;
whereby when said at least one induction plate comes into proximity to an associated one of said driving magnets during the rotation of said key within said lock, the magnetic field of said associated one of said driving magnets, acting through said induction plate, attracts the appropriate pole of said permanent magnet into abutting relationship with said abutment portion of said induction plate.

2 more elements

Dependencies are inferred from the claim text.