Magnetic lock and status detection system and method therefor

A method of detecting whether an electromagnetic lock assembly is properly closed and secured, comprising:

• characterizing electrical response characteristics of an electromagnet as a function of time and further as a function of a distance between the electromagnet and an armature;
• determining an appropriate time for measuring the electrical response after a voltage input to the electromagnet has been switched;
• switching power to the electromagnet for a brief period of time to provide a counter EMF pulse while maintaining a secure holding force;
• waiting a time period equal to the appropriate time;
• detecting the electrical response from said pulse at the determined appropriate time;
• and
• correlating the electrical response to a secured or unsecured status of the electromagnetic lock assembly.

An apparatus for detecting whether an electromagnetic lock is properly secured, comprising:

• a switch for altering a voltage level provided to the electromagnetic lock;
• a sensor for detecting an EMF produced within the electromagnetic lock in response to the voltage level being altered;
• an electromagnet;
• an armature magnetically attracted to the electromagnet into a mating relationship;
• a power supply for supplying the voltage level;
• a door on which the armature is mounted;
• a door frame on which the electromagnet is mounted such that the relative movement of the door between a closed position whereby the armature engages the electromagnet, and an opened position whereby the door is open and the armature is spaced from the electromagnet;
• a status detection unit;
• wherein the switch turns off power to the electromagnet for a short time period and the EMF is a counter EMF wherein the sensor detects the counter EMF and the status detection unit compares the counter EMF with a threshold voltage;
• wherein the door is opened and unsecured when the electromagnet is completely separated from the armature, and the counter EMF in the electromagnet is substantially zero at the appropriate time;
• wherein the door is closed and unsecured when a relatively large air gap is between the electromagnet and armature, and the counter EMF in the electromagnet is below the threshold range;
• wherein the door is closed and secured when the electromagnet is fully coupled to the armature, and the counter EMF in the electromagnet is within the threshold voltage range;
• and
• wherein the door is closed and unsecured when a relatively small gap is between the electromagnet and armature, and the counter EMF in the electromagnet is greater than the threshold voltage range.

A method of detecting the status of an electromagnetic lock assembly, comprising:

• providing an electromagnet and an armature;
• magnetically attracting the electromagnet and the armature into a mating relationship by providing power to the electromagnet;
• and
• monitoring locking strength between the electromagnet and the armature, comprising:
• switching off the power to the electromagnet for a short period of time less than 30 milliseconds to induce a counter EMF pulse in the electromagnet while maintaining secure holding force;
• measuring the counter EMF pulse during said short period of time;
• and
• actuating a status detection circuit responsive to the measurement of the counter EMF pulse.