Electromagnetic door lock assembly

An electronic circuit in an electromagnetic door lock for controlling the application of electrical power to a locking coil attached in a door frame, the locking coil being cooperatively arranged with an armature movably attached to a door in spaced relation to the locking coil, the electronic circuit comprising:

• door sensor means for triggering a timing circuit means, in response to a small permanent magnet in the door, when the magnet is inc lose proximity to said door sensor means, for producing a delayed output timing signal in response thereto;
• and
• power circuit means for applying power to the locking coil in response to said delayed output from said timing means, the power circuit means including enhancing means for developing an initial enhanced current through the electromagnet to assure enhanced attraction of the armature plate, to overcome a bias on said armature plate away from the electromagnet, across the space therebetween when the door is closed thereby attracting the armature plate away from a backing plate toward which said armature plate is biased so that the door assumes a magnetically locked condition when the locking coil is powered and the door is closed.

An adjustable armature assembly for use in an electromagnetic door lock comprising:

• an armature plate having a front surface confronting an electromagnet for magnetically interacting therewith and having a back surface opposite the front surface, a backing plate situated adjacent to the back surface of the armature plate, coupling means for coupling the backing plate to the armature plate including biasing means for biasing the backing plate and armature plate toward each other, a mounting unit for mounting the armature assembly to a door to be locked, adjustable elements engaging the mounting unit having upper portions projecting through openings in the backing plate and armature plate, and having upper ends substantially coplanar with the armature plate front surface, the adjustable elements adjustably positioning the backing plate at a selected position with respect to the mounting plate so that the front surface of the armature plate is positioned at a first position spaced from the electromagnet, the upper portions of the adjustable elements maintaining the relative alignment between the armature plate and the mounting plate as the armature plate moves between said first position and a position contiguous to the electromagnet.