Patent ID: 7355515

Claim:
A lock position detection device adapted to be mounted on a door, for securing entry from an outside region of the door to an inside region of the door, the lock position detection device comprising: a. a door locking mechanism comprising an actuator operable so as to be in a first position or a second position, the first position causing the door locking mechanism to lock the door and the second position causing the door locking mechanism to unlock the door; b. a magnetic field detection unit comprising i. a magnetic field sensor adapted to output a first signal when the magnetic field sensor detects a magnetic field and a second signal when the magnetic field sensor does not detect a magnetic field; ii. a wireless transmitter coupled to the magnetic field sensor for transmitting a radio frequency signal based on signals received from the magnetic field sensor; c. a magnet coupled to the door locking mechanism such that the magnet i. enters proximity of the magnetic field sensor when the actuator is operated to one of the first position or the second position and causes the magnetic field sensor to output the first signal; and ii. exits proximity of the magnetic field sensor when the actuator is operated to the other of the first position or the second position and causes the magnetic field sensor to output the second signal; and d. a magnetic field shield located with respect to the magnetic field sensor so as to prevent a magnetic field originating from the outside region of the door from being detected by the magnetic field sensor; wherein the magnetic field sensor is a reed switch and wherein the magnet enters and exits proximity of the reed switch substantially along a line that is offset from a centerline of the reed switch.