Patent Description:
Electronic door locks are commonly used in commercial settings and are increasingly being used in residential applications. Some of the electronic door locks can provide an alarm function or can be connected as an input to an alarm system to enhance the security of the building or facility.

Document <CIT> discloses a door has a movable door panel closing an access opening, and acceleration sensors for detecting acceleration of the door panel in one or two spatial directions. The acceleration sensors are attached at the door panel and/or at a lock e.g. mortise lock, of the door. An evaluation unit evaluates a signal generated by the acceleration sensors based on detected acceleration. The evaluation unit comprises a comparison unit that compares the signal of the acceleration sensors with a standard value.

Document <CIT> discloses a method for processing instantaneous acceleration measures furnished by an accelerometer along at least one direction with the aim of detecting a condition of the initiation of an alarm signal in which, in a first operating mode, acceleration measures ηk are successively carried out at predetermined time intervals Tk, at each instant, at least one value, called state value, is calculated according to a function of at least a portion of the acceleration measures ηk, each state value is compared to a threshold value, characterized in that if this state value is greater than the threshold value, a second operating mode is switched to, called alarm mode, in which acceleration measures η'k are successively carried out at predetermined time intervals T'k. The invention also relates to an acceleration sensor that carries out a method of the aforementioned type and to an alarm system equipped with sensors of this type.

In one embodiment, the invention provides a door assembly according to claim <NUM>.

In another embodiment the invention provides a method of determining the cause of a first acceleration at a door according to claim <NUM>.

<FIG> illustrates a doorway or door assembly <NUM> that includes a door panel <NUM> pivotally supported within a frame <NUM>. A lock mechanism <NUM> is coupled to the door panel <NUM> and operates to selectively inhibit movement of the door panel <NUM> from a closed position to an open position. The lock mechanism includes a latch <NUM> and an electronic actuator <NUM> having an interior portion <NUM> and an exterior portion attached to the door panel <NUM> to electronically control access via the door <NUM>. <FIG> illustrates the interior portion <NUM> of the electronic actuator <NUM>. Typically, the interior portion <NUM> of the electronic actuator <NUM> includes a housing <NUM> that covers the electronics that make the access decision and an actuator that moves the mechanical components to open the door <NUM>. The exterior portion of the electronic actuator <NUM> typically includes an input device such as a keypad, card reader, biometric scanner, and the like that read data from a user wishing to gain entry. The data provided at the exterior portion <NUM> of the electronic actuator <NUM> is then used to make an access decision or is transmitted to a remote device that makes the access decision.

Before proceeding, it should be noted that the description contained herein is directed to a system that includes an electronic actuator <NUM>. However, the present invention could be applied to purely mechanical door locks as well if desired.

As illustrated in <FIG>, the interior portion <NUM> of the electronic actuator <NUM> includes a housing <NUM> that contains a circuit board <NUM> that supports a power supply <NUM>, a sensor <NUM>, and a controller <NUM>. The power supply <NUM> includes one or more batteries <NUM> in the form of coin cells that are operable to provide the main power to the circuit board <NUM> or alternatively to provide back up power should a main power supply fail. In one construction, an AC power supply is provided as main power with the battery or batteries <NUM> providing back up power. It should be noted that many different batteries having many different voltage outputs, shapes, and sizes could be employed as desired.

The sensor <NUM> is positioned on the circuit board <NUM> and is connected to the power supply <NUM> and the controller <NUM>. In one construction the sensor <NUM> includes an accelerometer capable of measuring acceleration in one or more directions. In a preferred construction, a microelectromechanical system (MEMS) arrangement is employed as the accelerometer. The MEMS accelerometer is capable of measuring acceleration in one or more axes with three axes being preferred. Example of MEMS based accelerometers suitable for use in the illustrated device are manufactured by FREESCALE SEMICONDUCTOR having a principle place of business in Tempe, Arizona and sold under the part numbers MMA7330L and MMA7341L.

For purposes of this application, a single sensor <NUM> that measures acceleration in more than one direction can be considered as separate sensors <NUM> that each measure acceleration in a single direction or can be considered a single sensor <NUM>. Each of the suitable MEMS based accelerometers noted herein provides a unique output signal that corresponds to the acceleration in one of three directions. Thus, an external device receives three separate signals that could be provided by a single acceleration measuring device or three separate acceleration measuring devices. In other constructions, separate one axis sensors <NUM> can be employed to measure acceleration.

The controller <NUM> is positioned on the circuit board <NUM>, is powered by the power supply <NUM>, and receives signals from the sensor <NUM>. In one example construction not forming part of the claimed invention, the controller <NUM> receives a single acceleration signal. The signal is analyzed by the controller <NUM> to determine if the measured acceleration exceeds a predetermined threshold <NUM>. If the threshold <NUM> is exceeded, the controller <NUM> can store the measured data and can initiate an alarm if the measured data is indicative of an attempted forced entry. However, if according to this example only one axis of acceleration is measured, the system is susceptible to false alarms when the door panel <NUM> is slammed or closed quickly. Thus, in accordance with the invention, signals indicative of acceleration in two or more directions are provided to the controller <NUM>.

In some constructions, the controller <NUM> includes a micro-controller that is operable in a sleep state or an operating state to conserve power. When an acceleration is detected that exceeds a wake threshold <NUM>, the micro-controller or controller <NUM> transitions from the sleep state to the operating state to perform the analysis necessary to determine the cause of the acceleration.

<FIG> schematically illustrates the doorway <NUM> with the door panel <NUM> in the open position. The axes along which accelerations are measured are illustrated as an X-axis <NUM>, a Y-axis <NUM>, and a Z-axis <NUM>. The X-axis <NUM> extends in the width or horizontal direction from the edge <NUM> of the door panel <NUM> that is connected to the frame <NUM> to the edge <NUM> of the door panel <NUM> that selectively engages the door frame. The Y-axis is normal to the X-axis and extends vertically from the bottom edge of the door to the top edge of the door. The Z-axis is normal to the X-axis and the Y-axis and extends in a direction that is substantially tangent to an arc defined by the location of the accelerometer as the door moves between the open position and the closed position.

<FIG> graphically illustrates the measurements taken during a normal door closure with a system that measures acceleration in at least two directions. More specifically, <FIG> illustrates the accelerations measured in the X-axis as a first curve <NUM> and the Z-axis as a second curve <NUM> as the door panel <NUM> moves from a stationary open position to a stationary closed position. As the user begins to close the door panel <NUM>, acceleration is measured in both the X and Z directions. Eventually, the angular acceleration of the door panel <NUM> approaches zero such that the door panel <NUM> moves with a constant angular velocity toward the closed position. Thus, the accelerations in the Y-axis and Z-axis directions approach zero. However, the constant angular velocity of the door panel <NUM> does produce a substantially constant centripetal acceleration that is detected and displayed as acceleration in the X-axis direction. As the door panel <NUM> contacts the frame <NUM> near the closed position, the angular velocity (and the X-axis acceleration) begins to drop. Simultaneously, accelerations are measured in the Z-direction and potentially in the Y-direction. The magnitude of these accelerations and the direction of these accelerations vary depending on the velocity of the door panel <NUM> as well as the lock mechanism <NUM> employed. Thus, different patterns of acceleration will be produced by different doors <NUM> with the second curve <NUM> illustrating one example.

<FIG> also illustrates one possible wake threshold <NUM> and one possible alarm threshold <NUM>. Of course other threshold levels <NUM>, <NUM> could be employed if desired. In addition, the wake threshold <NUM> could be eliminated and the controller <NUM> could always remain in the operating state if desired.

The controller <NUM> will identify the curves of <FIG> as being indicative of a normal door closure. Specifically, the controller <NUM> will detect the accelerations at the end of the second curve <NUM> and will identify them as a potential attempted forced entry as they exceed the alarm threshold <NUM>. However, the non-zero level of acceleration immediately prior to the acceleration illustrated in the first curve <NUM> would be detected by the controller <NUM> and would indicate that the door panel <NUM> was moving just prior to the large acceleration. The controller <NUM> would thus determine the cause of the high acceleration indicated by the first curve <NUM> at least partially by analyzing the acceleration of the second curve <NUM> just prior to the large detected acceleration. Thus, if a user slams the door panel <NUM>, thereby producing accelerations at the end of the closure significantly higher than those illustrated or accelerations above the alarm set point <NUM>, the controller <NUM> will prevent the alarm from being triggered.

In non-claimed examples not forming part of the invention that employ a single axis sensor <NUM>, the sensor <NUM> will typically be oriented to measure accelerations along the Z-direction <NUM>. Thus, during a normal door closure as illustrated in <FIG>, only the second curve <NUM> will be available. However, the controller <NUM> can still identify this as a normal door closure event based on the initial acceleration caused as the user accelerates the door from a stationary condition to a moving condition followed a few seconds later by the accelerations produced during contact with the door frame <NUM>.

<FIG> illustrates the measured accelerations from the sensor <NUM> during an attempted forced entry. Typically, a forced entry produces significant acceleration in the Z-axis <NUM> with smaller accelerations in the X-axis <NUM> and Y-axis <NUM> directions. There is no acceleration similar to the X-axis <NUM> acceleration produced during movement of the door panel <NUM> toward the closed position, thereby making it easier for the controller <NUM> to identify this as an attempted forced entry rather than a normal closure. Thus, the controller can record the accelerations to document the attempted forced entry and can trigger an alarm even if the alarm threshold <NUM> is not exceeded.

As one of ordinary skill will realize, the controller <NUM> can be programmed to identify many different normal activities based on the measured accelerations to further reduce false alarms that might occur. The use of multiple accelerometers or a single accelerometer that measures acceleration in various directions provides additional information to the controller <NUM> to make it easier to filter normal activities from attempted forced entries.

The use of a multi-axis sensor <NUM> provides for the ability to monitor door openings and closings. Thus, the number of times a door opens or closes could be tracked and maintenance schedules could be set based on the number of openings and closings. In addition, the status of the doors could be monitored to verify that they are in the desired state. For example, doors that lead to secured areas could be monitored to verify that they are in the desired position. Thus, a door that is supposed to remain closed could be monitored to verify that the door closes within a predetermined time period after it opens. If the door does not close an alarm could be triggered. In arrangements not forming part of the invention that include only a single axis sensor <NUM>, other sensors could be employed such as a door position sensor, a latch position sensor, and the like. As one of ordinary skill will realize, the multi-axis sensor <NUM> is advantageous as it can monitor the door position and the door status without the need for an additional sensor.

Claim 1:
A door assembly (<NUM>) comprising:
a door panel (<NUM>) connected to a door frame (<NUM>) and pivotable about a pivot axis;
a door latch (<NUM>) coupled to the door panel (<NUM>) and operable to selectively inhibit movement of the door panel (<NUM>) from a closed position to an open position;
a sensor (<NUM>) coupled to the door latch (<NUM>) and operable to detect acceleration of the door and output acceleration data corresponding to the acceleration of the door panel (<NUM>) in a first direction, wherein the sensor (<NUM>) is operable to measure a first acceleration produced by a centripetal force and a second acceleration, and to generate signals indicative of the first acceleration and the second acceleration; and
a controller (<NUM>) coupled to the door latch (<NUM>) and the sensor, the controller (<NUM>) operable to analyse the acceleration data of the first acceleration and the second acceleration compared to acceleration data indicative of movement of the door panel (<NUM>) from the open position to the closed position to determine the cause of the acceleration, the controller being operable to determine the cause of the second acceleration at least partially in response to the acceleration data of the first acceleration.