Door knob lock monitoring alarm mechanism

DETAILED DESCRIPTION An interior door knob is described which includes, within its hollow body, an electrically energized circuit including a battery, a normally-open microswitch, and an electrically energized audio and/or optical indicator electrically connected in series for monitoring the status of locking mechanisms in conventional lockable door latches.
The microswitch is positioned within the knob housing such that a camming surface associated with an actuator which moves responsive to engagement and release of the locking mechanism closes the microswitch when the locking mechanism is in the release state for electrically energizing the audio and/or optical alarm indicators signaling that the door is not locked.
A particular embodiment of the invented self-contained, interior door knob lock monitoring alarm system includes a remote (external) pick-up responding to a unique acoustical/optical signal emitted from the door knob when the key activated exterior mechanism causes movement of the interior, manual actuator.
This embodiment is responsive to a change in state of the locking mechanism, to provide an intrusion alarm at the remote location.
In other embodiments, replacement interior door knobs for the most common types of lockable door latching mechanisms are described, each having a door knob housing adapted to mechanically engage/operate a particular type of spindle of the more common types of lockable door latches.
In each of the different embodiments, the knob housing has a cylindrical receptacle receiving a removable component module containing the electrical components of the system.
Some of the replacement door knobs also include coaxial, manually rotatable actuators which replace the existing interiorly operated manual actuator mechanisms and provide the camming surface for switching the microswitch.
The advantages, objects, features and aspects of inventive door knob lock monitoring alarm system will become apparent and are more fully described with reference to the following description and drawings of preferred and exemplary embodiments of the system