Abstract:
A door lock detection system is disclosed. The system includes a magnet flexibly attached to a strike plate. The strike plate includes an opening. The magnet extends across the opening of the strike plate in a first orientation when a bolt does not extend into the opening of the strike plate. The magnet is configured to be deflected from the first orientation to a second orientation, distinct from the first orientation, in response to the bolt being extended into the opening of the strike plate. The system includes a magnetometer configured to detect one or more magnetic fields of the magnet that is flexibly attached to the strike plate in the first orientation and in the second orientation.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority and benefit to U.S. Provisional Application No. 61/891,885, filed Oct. 16, 2013, entitled “Robust Sensing System for Verifying Engagement of a Deadbolt Bolt into a Deadbolt Strike Plate,” and to U.S. Provisional Application No. 61/897,768, filed Oct. 30, 2013, entitled “Robust Sensing System for Verifying Deadbolt Engagement Including Door Angle Sensing Subsystem.” All of these applications are incorporated by referenced herein in their entireties. 
     
    
     TECHNICAL FIELD 
       [0002]    This relates generally to door locks, including but not limited to sensing systems for verifying deadbolt engagement. 
       BACKGROUND 
       [0003]    As discussed in U.S. Pat. No. 6,950,033 to Guyre, entitled “Door Bolt Alarm,” which is incorporated by reference herein, it is desirable for purposes of home security and homeowner reassurance for a user to be able to know for certain whether a door to their home, such as a front door, is properly closed and that the deadbolt is properly engaged. Security systems, building automation systems, and HVAC systems all benefit from knowing the state of doors, such as whether they are open or closed, locked or unlocked, and the like. Several known deadbolt systems are able to verify that a bolt of the deadbolt system is either extended or retracted and are able to communicate this status in various ways to a user. However, the status of the bolt as being extended or retracted is not necessarily indicative of the true security state of the door. For example, it may be the case that the bolt is extended, but that the door is still partially open. Moreover, many existing systems require wiring to be installed in door frames and/or door jambs, which can be expensive and complicated to install and maintain. 
         [0004]    Thus, existing systems cannot reliably verify that a door has indeed been shut and that the deadbolt has indeed been properly engaged. Moreover, existing systems are complex and often include a multitude of sensors and require significant wiring. 
       SUMMARY 
       [0005]    Accordingly, it would be desirable to provide a system that can reliably verify that a door has indeed been shut and that the deadbolt has indeed been properly engaged. It would be further desirable to provide such a system in a manner that does not require a high degree of complexity, does not require an inordinate number of sensors, and does not require an inordinate number of wires. 
         [0006]    In accordance with some embodiments, a door lock detection system includes a magnet flexibly attached to a strike plate (e.g., by spring, hinge, or combination thereof). The strike plate includes an opening. The magnet extends across the opening of the strike plate in a first orientation when a bolt does not extend into the opening of the strike plate. The magnet is configured to be deflected from the first orientation to a second orientation, distinct from the first orientation, in response to the bolt being extended into the opening of the strike plate. The door lock detection system also includes a magnetometer configured to detect one or more magnetic fields of the magnet that is flexibly attached to the strike plate in the first orientation and in the second orientation. 
         [0007]    In accordance with some embodiments, a method is performed by a door lock detection system that has a magnet flexibly attached to a strike plate. The strike plate includes an opening. The magnet extends across the opening of the strike plate in a first orientation when a bolt does not extend into the opening of the strike plate. The magnet is configured to be deflected from the first orientation to a second orientation, distinct from the first orientation, in response to the bolt being extended into the opening of the strike plate. The door lock detection system also has a magnetometer configured to detect one or more magnetic fields of the magnet that is flexibly attached to the strike plate in the first orientation and in the second orientation; and a controller. The method includes detecting, with the magnetometer, one or more magnetic fields of the magnet that is flexibly attached to the strike plate; determining whether the detected one or more magnetic fields correspond to the magnet being in the second orientation; and based at least in part on determining that the detected one or more magnetic fields correspond to the magnet being in the second orientation, relaying, with the controller, to at least one other system information that indicates that the bolt is engaged in the strike plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    For a better understanding of the various described embodiments, reference should be made to the Description of Embodiments below, in conjunction with the following drawings in which like reference numerals refer to corresponding parts throughout the figures. 
           [0009]      FIG. 1A  is a front view of a deadbolt assembly in accordance with some embodiments. 
           [0010]      FIG. 1B  is a side view of a deadbolt assembly in accordance with some embodiments. 
           [0011]      FIG. 2A  is a front view of a deadbolt assembly in accordance with some embodiments. 
           [0012]      FIG. 2B  is a side view of a deadbolt assembly in accordance with some embodiments. 
           [0013]      FIGS. 3A-3B  are perspective views of a deadbolt assembly in accordance with some embodiments. 
           [0014]      FIGS. 4A-4D  are front views of a deadbolt assembly in accordance with some embodiments. 
           [0015]      FIGS. 5A-5D  are side views of a deadbolt assembly in accordance with some embodiments. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0016]      FIGS. 1A, 1B, 2A, and 2B  illustrate a sensing system for verifying that a door is properly shut and that a deadbolt is properly engaged. More particularly,  FIGS. 1A and 1B  illustrate front and side views, respectively, of a deadbolt assembly  102  mounted on a door  112  that has been shut into a door jamb  116 , wherein a bolt  104  of the deadbolt assembly  102  is in a retracted state. As with conventional systems, there is a deadbolt face plate  114  affixed to the door  112 , and a deadbolt strike plate  118  affixed to the door jamb  116 . In some embodiments, there is provided a magnet  108  that is flexibly and springably attached to the deadbolt strike plate  118 , such as by flex/spring member  109 , such that the magnet  108  extends across the opening of the deadbolt strike plate  118 . In some embodiments, the deadbolt assembly  102  is provided with a magnetometer  106 . The magnetometer  106  and the magnet  108  are mutually configured and dimensioned such that the magnetometer  106  can sense a change in orientation of the magnet  108 . In particular, when the magnet  108  is deflected, the magnetic field that is produced by the magnet is correspondingly deflected. In some embodiments, magnetic field readings from the magnetometer  106  are compared against previous readings to determine whether the readings correspond to a deflected magnetic field (e.g., resulting from the bolt  104  deflecting the magnet  108 ), or an undeflected magnetic field (e.g., resulting from the bolt  104  not deflecting the magnet  108 ). 
         [0017]      FIGS. 2A and 2B  illustrate corresponding front and side views, respectively, of the sensing system of  FIGS. 1A and 1B  in which the bolt  104  is in an extended state.  FIGS. 3A and 3B  illustrate perspective views,  FIGS. 4A-4D  illustrate front views, and  FIGS. 5A-5D  illustrate side views of the sensing system in accordance with some embodiments. As shown in  FIGS. 2A and 2B , the magnet  108  has changed its orientation by 90 degrees by virtue of the mechanical insertion of the bolt  104  through the opening of the deadbolt strike plate  118 , an orientation change that is detected by magnetometer  106 . In some embodiments, this change in orientation is communicated from the magnetometer  106  to one or more user interfaces using a variety of different electronics and communications configurations, such as those described in Guyre, supra. 
         [0018]    Advantageously, false engagement signals associated with the situation of an extended bolt but unclosed door are avoided, because the magnet  108  will not change orientation in that case. Conversely, false engagement signals associated with a situation of a rotated magnet  108  but non-extended bolt (such as by a person sticking their finger into the opening of the deadbolt strike plate) is also avoided, because if the door is not closed, then the magnetometer  106  will be too far from the magnet  108  to sense its orientation change. In some embodiments, false engagement signals are still further avoided by virtue of a separate sensing system (not shown) onboard the deadbolt assembly  102  for sensing whether the bolt has been extended (e.g., by optical sensing, electrical bumper switch, magnetic sensing, etc.). In such cases, the conclusion that the door has been closed and the deadbolt locked is reached when it is determined that both (a) the bolt has been extended (e.g., as determined by the separate sensing system), and (b) the magnet  108  has changed its orientation (e.g., as determined by the magnetometer  106 ). 
         [0019]    One example of a commercially available magnetometer suitable for use with the present system is an ASAHIKASEI AKM AK8963 3-axis electronic compass. In a calibration step in the locked position, the X, Y, and Z magnetic fields reported by the magnetometer are measured. Within a tolerance, when this same combination of fields is seen again (and, optionally, the bolt is known to be extended), it is determined that the door is securely locked. One example of a magnet that can be used is a Neodymium rare earth magnet, such as a Neodymium disc magnet having dimensions of 0.5 inch diameter by 0.125 inch thickness. 
         [0020]    The disclosed systems and methods use minimally invasive sensors to identify if a deadbolt is properly engaged in a doorframe, as opposed to merely detecting if the deadbolt is out but the door is not closed. Using a strike plate that mounts inside the doorframe, the bolt deflects a magnet when the bolt is properly engaged into the strike plate. Once the door is locked (i.e., the bolt is extended through an opening of the strike plate and into a door jamb), a magnetometer measures the magnetic field it senses. If the magnetometer senses a magnetic field substantially equivalent to the previously calibrated magnetic field (e.g., which corresponds to the magnetic field that is sensed when the bolt deflects the magnet in the latch in the doorframe), it is determined that the bolt is engaged properly in the doorframe and that the door is secured. A microcontroller relays this information to other systems such as a door mounted notification light or alarm, a security system, and/or a control panel. In some embodiments, the system is also connected to an electromechanical door locking/unlocking mechanism. 
         [0021]    The disclosed embodiments provide numerous advantages over conventional deadbolts. For example, as noted above, conventional deadbolts (even electromechanical ones) do not know if the bolt (when extended) actually extends into the door jamb securing the door; they just know if the bolt is extended or retracted. In the disclosed embodiments, however, there is no need for an electrical switch inside the door jamb to sense that the bolt is engaged. Rather, the sensor that determines whether the bolt is engaged or not is external to the door jamb and strike plate (e.g., it is coupled to a deadbolt assembly mounted to the door). Also, because there is no electrical switch, there is no need to run electrical wires inside the doorjamb. Indeed, in some embodiments, the strike plate is retrofitted into existing door jambs without additional wiring. Furthermore, the disclosed embodiments do not require redesigning conventional bolts or locking mechanisms, as the magnet and magnetometer are agnostic to the particular locking mechanism being used. Indeed, the disclosed embodiments will work well with both manually operated and electromechanical door locks to provide feedback if the deadbolt is actually engaged. 
         [0022]    In some embodiments, the deadbolt assembly  102  is further configured and adapted to sense the particular angle of the door (e.g., 0 degrees corresponding to a completely closed state, 10 degrees corresponding to a cracked or partially open state, 90 degrees corresponding to an open state, and so forth). For example, a microelectromechanical system (MEMs) magnetometer mounted to a door senses door orientation (i.e. closed, open, partially open) by measuring changes in orientation with respect to the earth&#39;s magnetic field or a reference magnetic field (e.g., a stationary a magnet or coil). In some embodiments, this MEMs magnetometer can be one and the same as the magnetometer  106 . For other embodiments, the door-angle-sensing MEMs magnetometer is a separate magnetometer than the magnetometer  106  provided with the deadbolt assembly  102 . In still other embodiments, the door-angle-sensing MEMs magnetometer is mounted in a separate device or structure on the door. In addition to or as an alternative to the door-angle-sensing MEMs magnetometer, a MEMs gyroscope (“gyro”) device is optionally included in the deadbolt assembly  102  or otherwise mounted to a door for measuring the angular rate of the door opening or closing. Knowing time, after integrating the gyro, the door&#39;s angular relative position from a known starting point is determined, thereby allowing determination of the door&#39;s absolute opening angle. By way of example and not by way of limitation, examples of suitable MEMs gyros include the BOSCH BMG160, the ST LPY410A, and the ST A3G4250D. 
         [0023]    Information regarding the door angle is useful in a variety of different ways. In some embodiments, the door angle information is used to verify that the door is indeed properly closed (i.e., completely closed, as opposed to partially or fully open). Another use includes communicating the door angle to a user interface screen of a user, so that the user can determine, from a remote location, whether and to what extent the door is open. Another useful application arises for doorways equipped with a screen door, (i.e., a second door that allows air to pass in and out while also keeping out insects and other pests), or for other doors such as interior doors that affect air circulation in the house. In such embodiments, the detected door angle is communicated to an HVAC system for any of a variety of useful purposes relating to the monitoring or governing of air flow in the home. Additionally, applications further include doors equipped with associated motors and linkages for achieving automated opening and closing, where the door angle is used as part of a feedback control system.