the other end of spring 52 engages lip 56 fig5 shows the electromagnetic lock installed in a door and door frame with the door in its fully closed position armature 28 abuts electromagnet 18 and is electromagnetically locked to it as shown in detail in fig5 a spring 52 defines a resilient member that biases plunger 46 into shaft 42 this draws armature 28 against door 10 thus providing a bias means mounted within a volume defined by door 10 for providing a bias that urges the door toward its fully closed position permanent magnet 40 is sufficiently proximate to sensor assembly 24 to activate two of the three reed switches therein thus signaling to system controller 80 fig2 that the door is in its fully closed position fig6 shows the components of fig5 when someone is attempting to exit the building the person first pushes panic bar 12 fig1 or similar door activating device to release the latch the person is then able to push the door away from its fully closed position to the activation position shown in fig6 to do so the person must supply sufficient external force to overcome the bias provided by spring 52 spring 52 must therefore be chosen to provide a small enough force so that even a small or frail person can push the door to the activation position at the same time the spring should provide enough bias so that when the door is pushed momentarily and then released as for example by a vandal the door will tend to overcome the resistance of the latch mechanism and return the door to its fully closed position accordingly spring 52 is chosen.