| 摘要 |
<p>PURPOSE:To electrically detect the presence or absence of a key by a simple construction and positively. CONSTITUTION:A shutter 6 made of magnetic substance for opening and closing a key-slot 5 is provided to a rotor 3 of a key cylinder body 1 so that it can be turned, and the shutter 6 is energized by a spring to the direction of closing it. When the shutter 6 is in a closed state, a reed switch 10 is subjected to magnetic force of a permanent magnet 9 to be held in OFF state. When a key is inserted to turn the shutter 6 in the direction of opening it, the permanent magnet 9 becomes a state where it is covered by the shutter 6, magnetic force of the permanent magnet 9 to the reed switch 10 is intersepted by the shutter 6, and the reed switch 10 is in ON state.</p> |
