Wirelessly charged electronic lock with open/closed status reporting

A wirelessly charged battery powered electronic door locking system utilizes a first radio frequency to wirelessly transmit a wireless charging signal from an electronic control module to an electronic lock module mounted with the door. A rechargeable battery associated with the electronic lock module powers the electronic lock module and is recharged thereby. An RFID reader may be coupled to the electronic lock module, powered by the battery and mounted with the door.

TECHNICAL FIELD

The present disclosure relates to systems and methods used to wirelessly recharge a battery, such as a battery that powers a door lock.

BACKGROUND

In the field of wireless electronic systems powered by rechargeable batteries, there exists a need for a system that can recharge a rechargeable battery wirelessly, particularly in connection with wireless electronic door locking systems. Typical existing electronic door locks are powered by non-rechargeable and relatively bulky battery packs. Such non-rechargeable battery packs need to be replaced periodically (typically annually) which requires costly labor, new batteries and disposal of the old batteries. In large facilities with many electronic door locks the costs can be significant. Installation of such locks can require special core drilling of the door and/or electronic transfer hinges to bring power and door control signals to the lock.

OVERVIEW

The subject matter described herein generally relates to apparatus, systems, methods and associated computer instructions for implementing a wirelessly charged battery powered electronic door locking system.

The foregoing overview is a summary and thus may contain simplifications, generalizations, and omissions of detail; consequently, those skilled in the art will appreciate that the overview is illustrative only and is not intended to be in any way limiting.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The flow, block, circuit and physical diagrams in the attached figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flow diagrams or block diagrams may represent a module, segment, or portion of code, which includes one or more executable instructions for implementing the specified logical function(s). It will also be noted that each block of the block diagrams and/or flow diagrams, and combinations of blocks in the block diagrams and/or flow diagrams, may be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. These computer program instructions may also be stored in a computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instruction means which implement the function/act specified in the flow diagram and/or block diagram block or blocks.

The systems and methods described herein disclose an apparatus and methods that are configured to wirelessly recharge a rechargeable battery that is associated with, and powers, an electronic door locking system. The system includes an electronic lock module attached to a door. The electronic lock module is electrically coupled to a rechargeable battery, which powers both the electronic lock module and an electronic door lock associated with the door. In an embodiment the electronic lock module, battery and lock may be integrated into one or several packages. In an embodiment, an electronic control module is physically coupled (attached) to a door frame corresponding to the door. The electronic control module receives periodic input data from the electronic lock module, wherein the input data includes the status of the charge on the rechargeable battery. The electronic control module processes the data received from the electronic lock module and determines whether the charge on the rechargeable battery has fallen below a threshold value, wherein the threshold value is either a predetermined threshold value, or the threshold value is dynamically computed based on a plurality of variables that include but are not limited to the age of the battery, the temperature of the battery, the ambient temperature and the use rate. If the electronic control module determines that the charge on the rechargeable battery has fallen below the threshold value, the electronic control module wirelessly transmits a charging signal to the electronic lock module. The electronic lock module wirelessly receives this charging signal and uses this charging signal to charge the rechargeable battery, thereby eliminating the need for periodic inspection or maintenance of the door lock in order to replace or otherwise service non-rechargeable batteries of a disposable battery pack. Charging may be continuous or on demand.

FIG. 1is a block diagram illustrating an embodiment of a wireless battery charging system100. In this embodiment, the system is comprised of an electronic lock module106attached to a door104. An electronic control module102is located in proximity to the electronic lock module106, but is physically separate from the electronic lock module106and physically separate from the door104. In some embodiments, the electronic control module102is attached to the door frame corresponding to the door104. In other embodiments, the electronic control module102can be attached to a wall adjacent to the door frame corresponding to the door104. The electronic control module102can be located anywhere, as long as the electronic control module102and the electronic lock module106are able to establish a bidirectional data communications link112and a wireless charging link114. The bidirectional data communications link112allows bidirectional exchange of data between the electronic control module102and the electronic lock module106. The data transmitted over the bidirectional data communications link112includes, but is not limited to, the status of the charge on a rechargeable battery108as transmitted over the bidirectional data communications link112by the electronic lock module106to the electronic control module102. Some other functions which may be supported in various embodiments may include a Request-To-Exit command, Lock Status (e.g., locked or unlocked), and a supervisory/status signal to verify that communications with the electronic lock module are working. In some embodiments, the data transmitted over the bidirectional data communications link112is encrypted by using an encryption method such as the Advanced Encryption Standard (AES). Other encryption methods may also be used to encrypt the data transmitted over the bidirectional data communications link112. In other embodiments, the wireless charging link114is a unidirectional wireless link that wirelessly transmits a charging signal used to recharge rechargeable battery108. The wireless charging link114wirelessly transmits the charging signal from the electronic control module102to the electronic lock module106. Example methods used to implement the bidirectional data communications link112and the wireless charging link114include radio frequency (RF), inductive coupling, magnetic coupling and infrared (IR) or any combination of these. Examples of RF wireless communication links include Bluetooth, Bluetooth Low Energy, ZigBee or any other wireless bidirectional RF data communications link. Examples of inductive coupling links (sometimes referred to herein as antennas or coils) include wire-wound solenoids and air-wound coils. Examples of IR wireless communication links include optical communication links implemented by using infrared diodes and infrared laser diodes. In some embodiments, the wireless charging link114is also used to communicate unidirectional data as well, from the electronic control module102to the electronic lock module106, in which case the bidirectional data communications link112now transmits unidirectional data, from the electronic lock module106to the electronic control module102. The rechargeable battery108is attached to the door104and is used to power an electronic door lock110. In some embodiments, the rechargeable battery108is used to power the electronic lock module106, while the electronic control module102is powered by a source independent of the rechargeable battery108.

During operation of an embodiment of system100, the electronic lock module106periodically monitors the charge status on the rechargeable battery108. The electronic lock module106periodically transmits the charge status on the rechargeable battery108to the electronic control module102via the bidirectional data communications link112. The electronic control module102receives the periodic updates on the charge status on the rechargeable battery108from the electronic lock module106via the bidirectional data communications link112. The electronic control module102identifies the charge status on the rechargeable battery108and compares the value of the charge on the rechargeable battery108to a threshold value. In one embodiment, the threshold value is 85% of the charge on the fully-charged battery. If the value of the charge on the rechargeable battery108has dropped below the threshold value, the electronic control module102determines that the battery needs to be recharged. If the battery needs to be charged, the electronic control module102wirelessly transmits a charging signal to the electronic lock module106via the wireless charging link114. This embodiment thus implements a non-continuous charging method, wherein the charging signal is not transmitted wirelessly all the time, but is transmitted non-continuously based on the charge status of the rechargeable battery108.

During the operation of another embodiment of system100, the electronic control module102continuously transmits wirelessly a charging signal to the electronic lock module106via the wireless charging link114, regardless of the status of the charge on the rechargeable battery108. This embodiment thus implements a continuous charging method, wherein the charging signal is transmitted wirelessly all the time.

FIG. 2Ais a process flow diagram illustrating an embodiment of a method200for monitoring the status of rechargeable battery108and wirelessly recharging the rechargeable battery when necessary via the wireless charging link114. The method200is a non-continuous charging method. At202, the method200monitors the status of the charge on the rechargeable battery108used to power the electronic door lock110. The status of the charge on the rechargeable battery108is monitored by the electronic lock module106. Next, at204, the electronic lock module106transmits the status of the charge on the rechargeable battery108via the bidirectional data communications link112to the electronic control module102. At206, the electronic control module102receives the status of the charge on the rechargeable battery108transmitted by the electronic lock module106via the bidirectional data communications link112.

At208, the electronic control module compares the status of the charge on the rechargeable battery108to a threshold value. If the charge on the rechargeable battery108is greater than or equal to the threshold value (as determined at210), the method200returns back to202since no recharging is required for the rechargeable battery108. If the charge on the rechargeable battery108is less than the threshold value, the method200charges the rechargeable battery at212by wirelessly transmitting a charging signal over the wireless charging link114, after which the method200returns to initial step202.

FIG. 2Bis a process flow diagram illustrating an embodiment showing details of a method for wirelessly charging the rechargeable battery (shown as212inFIG. 2a)108via the wireless charging link114. At214, the electronic control module102wirelessly transmits a charging signal to the electronic lock module106via the wireless charging link114. At216, the electronic lock module106wirelessly receives the charging signal transmitted by the electronic control module102via the wireless charging link114. At218, the electronic lock module106charges the rechargeable battery108used to power the electronic door lock110, where the electronic control module102continuously transmits the charging signal to the electronic lock module106via the wireless charging link114. At220, the method212checks if the rechargeable battery108is sufficiently charged, wherein the term “sufficiently charged” is used to denote that the rechargeable battery108is charged to a value that is around 100% capacity, where this value can be less than 100% capacity. Sufficiently charging the rechargeable battery108can include, for example, charging the rechargeable battery108up to 95% capacity, and includes cases where, for example, the rechargeable battery108is not able to charge up to a 100% charge capacity due to aging. If the rechargeable battery108is not sufficiently charged, then the method212returns back to214. If the rechargeable battery108is sufficiently charged, then the method212stops transmitting the charging signal at221and continues to222, where it returns to202.

FIG. 2Cis a flow diagram illustrating an alternate embodiment showing details of a method for wirelessly charging the rechargeable battery (shown as212inFIG. 2a)108via the wireless charging link114. At224, the electronic control module102wirelessly transmits a charging signal to the electronic lock module106via the wireless charging link114. At226, the electronic lock module106wirelessly receives the charging signal transmitted by the electronic control module102via the wireless charging link114. At228, the electronic lock module106charges the rechargeable battery108used to power the electronic door lock110. At230, the method monitors the time period for the charging process. At232, the method212also checks if the time period for the charging process is less than 30 minutes. Alternate embodiments may use time periods shorter or longer than 30 minutes. If the time period for the charging process is less than 30 minutes, then the method212proceeds to234; if the time period for the charging process is greater than 30 minutes, then the method stops transmitting the charging signal at236and waits for at least 5 minutes, at238, before proceeding to234where the electronic control module102continues transmitting the charging signal to the electronic lock module106via the wireless charging link114. At the next step240, the method212checks if the rechargeable battery108is sufficiently charged, where the term “sufficiently charged” is used to denote that the rechargeable battery108is charged to a value that is around 100% capacity, and this value can be less than 100% capacity. Sufficiently charging the rechargeable battery108can include, for example, charging the rechargeable battery108up to 95% capacity, and includes cases where, for example, the rechargeable battery108is not able to charge up to a 100% charge capacity due to aging. If the rechargeable battery108is not sufficiently charged, then the method returns back to224. If the rechargeable battery108is sufficiently charged, then the method stops transmitting the charging signal at241and goes to242, where it returns to202.

FIG. 3is a block diagram illustrating an embodiment of a wireless battery charging system300. This embodiment shows the electronic control module102and the electronic lock module106discussed above. Also shown are the rechargeable battery108and the electronic door lock110. In one embodiment, the electronic lock module106includes a microprocessor314, a 433 MHz RF transmitter304, a 915 MHz RF receiver302, and a battery charge module310. In one embodiment, the rechargeable battery108supplies power to the electronic door lock110, the microprocessor314, and the 433 MHz transmitter304, via the electronic lock module power supply bus318. The 433 MHz RF transmitter304receives a signal from microprocessor314, and outputs an RF signal at a frequency of 433 MHz. This RF signal is output to an RF antenna308for transmission through a unidirectional RF data communications link334. The 915 MHz RF receiver302is powered by the wireless RF signal received by an RF antenna306over a unidirectional RF data communications link336.

In one embodiment, the electronic control module102includes a microprocessor320, a 915 MHz RF transmitter322, a 433 MHz RF receiver324and host I/O344. In this embodiment, the microprocessor320, the 915 MHz RF transmitter322, the 433 MHz RF receiver324and the host I/O344are powered from an external power supply330via an electronic control module power supply bus332. The 915 MHz RF transmitter322receives a signal from microprocessor320, and outputs an RF signal at a frequency of 915 MHz. This RF signal is output to RF antenna328for transmission through the unidirectional RF data communications link336. The 433 MHz RF receiver324is receives an RF signal via the RF antenna326over the unidirectional RF data communications link334and outputs this signal to the microprocessor320.

The two unidirectional wireless RF data communications links334and336collectively constitute the bidirectional data link112. In this embodiment, the bidirectional data link is a wireless RF data link. Furthermore, the wireless charging link114is implemented by the unidirectional RF data communications link336. Thus, the unidirectional RF data communications link336wirelessly transmits both data and the charging signal from the electronic control module102to the electronic lock module106.

In one embodiment, the microprocessor314in the electronic lock module106periodically monitors the status of the charge on the rechargeable battery108. The microprocessor314transmits this status of the charge on the rechargeable battery108as a data signal to the 433 MHz RF transmitter304, which outputs this data signal to the RF antenna308that is electrically coupled to the 433 MHz RF transmitter304. The RF antenna308transmits the data signal comprising the status of the rechargeable battery108over the unidirectional RF data communications link334. This data signal is received by the RF antenna326electrically coupled to the 433 MHz RF receiver324that is a part of the electronic control module102. The data signal received by the 433 MHz RF receiver324is transmitted to the microprocessor320. The microprocessor320compares the received data signal, which is the status of the charge on the rechargeable battery, with a threshold value. If the status of the charge on the rechargeable battery is less than the threshold value, the microprocessor320transmits a charging signal to the 915 MHz RF transmitter322. The 915 MHz RF transmitter322transmits this charging signal to RF antenna328which is electrically coupled to the 915 MHz RF transmitter322. The RF antenna328wirelessly transmits the charging signal over the unidirectional RF data communications link336. The charging signal is wirelessly received by the RF antenna306which is electrically coupled to the 915 MHz RF receiver302. The RF antenna306wirelessly transmits the received charging signal to the 915 MHz RF receiver302. The charging signal is used to power the 915 MHz RF receiver302and the battery charge module310, and the charging signal is also transmitted to the battery charge module310, which transmits the charging signal to charge the rechargeable battery108via a charging path312. This embodiment implements the non-continuous charging method. In this embodiment, data from the electronic control module102is wirelessly transmitted to the electronic lock module106via the unidirectional RF data communications link336in a non-continuous manner, along with the wirelessly transmitted charging signal.

In another embodiment, the microprocessor320continuously transmits a charging signal to the 915 MHz RF transmitter322regardless of the status of the status of the charge on the rechargeable battery108. The 915 MHz RF transmitter322transmits this charging signal to RF antenna328which is electrically coupled to the 915 MHz RF transmitter322. The RF antenna328wirelessly transmits the charging signal over the unidirectional RF data communications link336. The charging signal is wirelessly received by the RF antenna306which is electrically coupled to the 915 MHz RF receiver302. The RF antenna306wirelessly transmits the received charging signal to the 915 MHz RF receiver302. The charging signal is used to power the 915 MHz RF receiver302and the battery charge module310, and the charging signal is also transmitted to the battery charge module310, which transmits the charging signal to charge the rechargeable battery108via charging path312. This embodiment implements the continuous charging method. In this embodiment, data from the electronic control module102can be wirelessly transmitted to the electronic lock module106via the unidirectional RF data communications link336in a continuous manner, along with the wirelessly transmitted charging signal.

In some embodiments, a door sense module316monitors a status of the door104, such as door open, door ajar, door shut and latch/bolt position sense. The door sense module316periodically transmits a door status data signal to the microprocessor314. This door status data signal is transmitted by the microprocessor314to the 433 MHz RF transmitter304, which then transmits this door status data signal to RF antenna308that is electrically coupled to the 433 MHz RF transmitter304. The door status data signal is transmitted by the RF antenna308over the unidirectional RF data communications link334. The door status data signal is received by RF antenna326that is electrically coupled to the 433 MHz RF receiver324. RF antenna326transmits the received door status data signal to the 433 MHz RF receiver324, which then transmits the door status data signal to microprocessor320for subsequent processing (e.g., to determine if the door is open or closed based on the magnitude and/or behavior or the signal received).

In other embodiments, the electronic lock module106periodically transmits a data signal to the electronic control module102via the unidirectional RF data communications link334. The contents of this data signal include the charge status on the rechargeable battery108and the status of the door. This periodically transmitted data signal may be referred to as a heartbeat signal. In other embodiments, the monitoring of the door status is performed by the electronic control module102.

Electronic control module102is also electrically coupled via an electrical coupling342to credential I/O module340. The credential I/O module340reads an input from a user for authentication purposes. User input methods include, for example, magnetic cards, biometric devices, RFID cards, keypads, and smart devices such as smartphones and PDAs that use communication protocols such as Near Field Communication (NFC). The credential I/O module340transmits user input to the electronic control module102for authentication. The credential I/O module340also receives input from the electronic control module102via the electrical coupling342, including user feedback that includes, but is not limited to, audio-visual signals either confirming or denying permission to enter.

In some embodiments, the credential I/O module340is physically attached to the door104and electrically coupled to the electronic lock module106. In this embodiment, the credential I/O module340, powered by rechargeable battery108, reads an input from a user for authentication purposes. The credential I/O module340transmits user input to the electronic control module102for authentication via the unidirectional RF data communications link334. The credential I/O module340also receives input from the electronic control module102via the unidirectional RF data communications link336, including user feedback that includes, but is not limited to, audio-visual signals either confirming or denying permission to enter.

Electronic control module102is also electrically coupled via an electrical coupling338to the access control module328via the host I/O344. The interface between the host I/O344and the access control module328is used for purposes such as user authentication, discussed in greater detail in the description ofFIG. 4. In some embodiments, the electrical coupling338between the host I/O344and the access control module328is realized by standard connectivity methods that include, but are not limited to, Ethernet, Wi-Fi, RS485, RS422, RS232, or other wired or wireless communication methods.

In some embodiments, RF antennas306,308,326and328are functions of the physical separation between the electronic control module102and the electronic lock module106. In one embodiment, antennas308and326are traces on a printed circuit board not to exceed 1.5 inches in length. In another embodiment, antennas306and328are 3.2 inches, or less, in length, and 0.6 inches in width.

FIG. 4is a process flow diagram illustrating an embodiment of a method400for authenticating a user to determine whether to unlock the door. In some embodiments, the electronic door lock110is locked by default. The method400receives user credentials at402. In some embodiments, user credentials are received by the electronic control module102from the credential I/O module340, via the electrical coupling342. The host I/O344transmits the user credentials to the access control module328via electrical coupling338in order to authenticate the user at404. The access control module328processes the user credentials and determines the authenticity of the user at406. The access control module328transmits the decision on user authenticity back to the host I/O344. In some embodiments, the access control module comprises a numeric keypad that is used by a user to enter credential information. If the user is not a valid user, then the method400transmits a user appropriate feedback signal to the user and the door104is not unlocked, at410. The user feedback signal is transmitted from the electronic control module102to the credential I/O module340via the electrical coupling342. The credential I/O module340displays the appropriate feedback to the user via methods that include audio and visual feedback. If the authentication406determines that the user is a valid user, then the method400transmits an appropriate feedback signal to the user and the door104is unlocked, at408. In some embodiments, the decision to unlock the door104by the access control module328is made based on other criteria in addition to the user credentials, wherein the criteria may include but are not limited to the time-of-day, whether the day that access is requested is a weekend or a holiday, whether the building is in lockdown mode, the maximum number of people allowed in a room or within the building, and so on.

The user feedback signal is transmitted from the electronic control module102to the credential I/O module340via the electrical coupling342. The credential I/O module340displays the appropriate feedback to the user via methods that include audio and visual feedback. The door unlock process involves the control module102sending a door unlock command data signal to the electronic lock module106via the unidirectional RF data communications link336. In order to achieve this, the microprocessor320sends the door unlock command data signal to the 915 MHz RF transmitter322, which then transmits the door unlock command data signal over the unidirectional RF data communications link336via RF antenna328. The electronic lock module106receives the door unlock command data signal. This is achieved by the RF antenna306receiving the door unlock command data signal over the unidirectional RF data communications link336. The RF antenna306then transmits the received door unlock command data signal to the 915 MHz RF receiver302, which transmits this door unlock command data signal to the microprocessor314which issues a command to the electronic lock to unlock the door104. The method400then returns to402and the process repeats.

FIG. 5is a block diagram illustrating another embodiment of a wireless battery charging system500. Many of the components shown inFIG. 5are similar to the components shown inFIG. 3and, therefore, are identified with the same reference numbers. This embodiment shows the electronic control module102and the electronic lock module106. Also shown are the rechargeable battery108and the electronic door lock110. In one embodiment, the electronic lock module106includes the microprocessor314, the 433 MHz RF transmitter304, a 100 kHz receiver502, and the battery charge module310. In one embodiment, the rechargeable battery108supplies power to the electronic door lock110, the microprocessor314, and the 433 MHz transmitter304, via the electronic lock module power supply bus318. The 433 MHz RF transmitter304receives a signal from microprocessor314, and outputs an RF signal at a frequency of 433 MHz. This RF signal is output to RF antenna308for transmission through the unidirectional RF data communications link334. The 100 kHz receiver502is powered by a wireless signal received by a solenoid506over a unidirectional inductively coupled wireless communications link536. In other embodiments, the unidirectional link536may be comprised of a magnetically coupled link. The unidirectional inductively coupled wireless communications link536is configured to wirelessly transmit both data and a charging signal that is used to recharge the rechargeable battery108.

In one embodiment, the electronic control module102includes microprocessor320, a 100 kHz transmitter522, the 433 MHz RF receiver324and host I/O344. In this embodiment, the microprocessor320, the 100 kHz transmitter522, the 433 MHz RF receiver324and the host I/O344are powered from external power supply330via the electronic control module power supply bus332. The 100 kHz transmitter522receives a signal from microprocessor320, and outputs a signal at a frequency of 100 kHz. This 100 kHz signal is output to solenoid528for transmission over the unidirectional inductively coupled wireless communications link536. The 433 MHz RF receiver324receives an RF signal via the RF antenna326over the unidirectional RF data communications link334and outputs this signal to the microprocessor320.

In this embodiment, the unidirectional wireless RF data communications link334and the unidirectional inductively coupled wireless communications link536collectively constitute the bidirectional data link112. Furthermore, the wireless charging link114is implemented by the unidirectional inductively coupled wireless communications link536. Thus, the unidirectional inductively coupled wireless communications link536wirelessly transmits both data and the charging signal from the electronic control module102to the electronic lock module106.

In one embodiment, the microprocessor314in the electronic lock module106periodically monitors the status of the charge on the rechargeable battery108. The microprocessor314transmits this status of the charge on the rechargeable battery108as a data signal to the 433 MHz RF transmitter304, which outputs this data signal to the RF antenna308that is electrically coupled to the 433 MHz RF transmitter304. The RF antenna308transmits the data signal comprising the status of the rechargeable battery108over the unidirectional RF data communications link334. This data signal is received by the RF antenna326electrically coupled to the 433 MHz RF receiver324that is a part of the electronic control module102. The data signal received by the 433 MHz RF receiver324is transmitted to the microprocessor320. The microprocessor320compares the received data signal, which is the status of the charge on the rechargeable battery, with a threshold value. If the status of the charge on the rechargeable battery is less than the threshold value, the microprocessor320transmits a charging signal to the 100 kHz transmitter522. The 100 kHz transmitter522transmits this charging signal to solenoid528which is electrically coupled to the 100 kHz transmitter522. The solenoid528wirelessly transmits the charging signal over the unidirectional inductively coupled wireless communications link536. The charging signal is wirelessly received by the solenoid506which is electrically coupled to the 100 kHz receiver502. The solenoid506transmits the received charging signal to the 100 kHz receiver302. The charging signal is used to power the 100 kHz receiver502and the battery charge module310, and the charging signal is also transmitted to the battery charge module310, which transmits the charging signal to charge the rechargeable battery108via charging path312. This embodiment implements the non-continuous charging method. In this embodiment, data from the electronic control module102is wirelessly transmitted to the electronic lock module106via the unidirectional inductively coupled wireless communications link536in a non-continuous manner, along with the wirelessly transmitted charging signal.

In another embodiment, the microprocessor320transmits a charging signal to the 100 kHz transmitter522regardless of the status of the charge on the rechargeable battery108. The 100 kHz transmitter522transmits this charging signal to solenoid528which is electrically coupled to the 100 kHz transmitter522. The solenoid528wirelessly transmits the charging signal over the unidirectional inductively coupled wireless communications link536. The charging signal is wirelessly received by the solenoid506which is electrically coupled to the 100 kHz receiver502. The solenoid506transmits the received charging signal to the 100 kHz receiver302. The charging signal is used to power the 100 kHz receiver502and the battery charge module310, and the charging signal is also transmitted to the battery charge module310, which transmits the charging signal to charge the rechargeable battery108via charging path312. This embodiment implements the continuous charging method. In this embodiment, data from the electronic control module102can be wirelessly transmitted to the electronic lock module106via the unidirectional inductively coupled wireless communications link536in a continuous manner, along with the wirelessly transmitted charging signal.

In some embodiments, both solenoids528and506and the associated transmitter522and receiver502are resonant at (i.e., are tuned to) a frequency of 100 kHz. In other embodiments, the resonant frequency may be a frequency different from 100 kHz.

In other embodiments, the door sense module316monitors a status of the door104, such as door open, door ajar, door shut and latch/bolt position sense. The door sense module316periodically transmits a door status data signal to the microprocessor314. This door status data signal is transmitted by the microprocessor314to the 433 MHz RF transmitter304, which then transmits this data signal to RF antenna308that is electrically coupled to the 433 MHz RF transmitter304. The door status data signal is transmitted by the RF antenna308over the unidirectional RF data communications link334. The door status data signal is received by RF antenna326that is electrically coupled to the 433 MHz RF receiver324. RF antenna326transmits the received door status data signal to the 433 MHz RF receiver324, which then transmits the door status data signal to microprocessor320for subsequent processing.

In other embodiments, the electronic lock module106periodically transmits a data signal to the electronic control module102via the unidirectional RF data communications link334. The contents of this data signal include the charge status on the rechargeable battery108and the status of the door. This periodically transmitted data signal may be referred to as a heartbeat signal. In other embodiments, the monitoring of the door status is performed by the electronic control module102.

Electronic control module102is also electrically coupled via an electrical coupling342to credential I/O module340. The credential I/O module340reads an input from a user for authentication purposes. User input methods include, for example, magnetic cards, biometrics, keypads, and smart devices such as smartphones and PDAs that use communication protocols such as Near Field Communication (NFC). The credential I/O module340transmits user input to the electronic control module102for authentication. The credential I/O module340also receives input from the electronic control module102via the electrical coupling342, including user feedback that includes, but is not limited to, audio-visual signals either confirming or denying permission to enter.

In some embodiments, the credential I/O module340is physically attached to the door104and electrically coupled to the electronic lock module106. In this embodiment, the credential I/O module340, powered by rechargeable battery108, reads an input from a user for authentication purposes. The credential I/O module340transmits user input to the electronic control module102for authentication via the unidirectional RF data communications link334. The credential I/O module340also receives input from the electronic control module102via the unidirectional inductively coupled wireless communications link536, including user feedback that includes, but is not limited to, audio-visual signals either confirming or denying permission to enter.

Electronic control module102is also electrically coupled via an electrical coupling338to the access control module328via the host I/O344. The interface between the host I/O344and the access control module328is used for purposes such as user authentication, discussed in greater detail in the description ofFIG. 4. In some embodiments, the electrical coupling338between the host I/O344and the access control module328is realized by standard connectivity methods that include, for example, Ethernet or Wi-Fi.

In some embodiments, RF antennas308and326are functions of the physical separation between the electronic control module102and the electronic lock module106. In one embodiment, antennas308and326are traces on a printed circuit board not to exceed 1.5 inches in length.

In some embodiments, solenoids506and528are comprised of ferrite cores. In other embodiments, solenoids506and528may be replaced by air wound coils. In other embodiments, solenoids506and528include cores that are comprised of materials with high magnetic permeability. Example dimensions of solenoids include but are not limited to 0.275 inches in diameter and 1.5 inches in length.

In some embodiments, the transmission frequency associated with the unidirectional inductively coupled wireless communications link536may be different from 100 kHz, for example the transmission frequency could be 135 kHz, or as high as 400 kHz. In other embodiments, the unidirectional RF data communications link334may be replaced by a unidirectional inductively coupled wireless communications link that is similar to the unidirectional inductively coupled wireless communications link536. This unidirectional inductively coupled wireless communications link may be comprised of solenoids similar to solenoids506and528, and include the corresponding transmitter and receiver similar to522and502respectively, at the appropriate transmission frequency.

FIG. 6is a diagram illustrating a physical implementation of certain components of an embodiment of the wireless battery charging system600. This embodiment shows the solenoid528associated with the electronic control module102, wherein the solenoid528is mounted on (or mounted within) the door frame602. The solenoid506associated with the electronic lock module106is mounted on (or mounted within) the door104. In this embodiment, the solenoids506and528are positioned such that they are coaxial. In another embodiment, the solenoids506and528may not be coaxial. The solenoids506and528generate the unidirectional inductively coupled wireless communications link536.

FIG. 7is a diagram illustrating a physical implementation of certain components of an embodiment of the wireless battery charging system700. In this embodiment, the solenoid528associated with the electronic control module102, also referred to as the exciter antenna, is mounted on (or within) the door frame602. Mounting positions702,704and706show some different possible mounting locations in which the solenoid506associated with the electronic lock module106, also referred to as the receiver antenna, is mounted on (or within) the door104. These mounting positions702,704and706are possible because the solenoids528and506do not have to be coaxial in order to establish the unidirectional inductively coupled wireless communications link536. In an embodiment, the receiver antenna506can be up to 1 inch from the exciter antenna528, and offset center-to-center by up to 0.5 inches.

FIG. 8is diagram illustrating a physical implementation of certain components of an embodiment of the wireless battery charging system800. In this embodiment, the solenoid506associated with the electronic lock module106, also referred to as the receiver antenna, is mounted on (or within) the door104. Mounting positions802,804and806show different possible mounting locations in which the solenoid528associated with the electronic control module102, also referred to as the exciter antenna, is mounted on (or within) the door frame602. These mounting positions802,804and806are possible because the solenoids528and506do not have to be coaxial in order to establish the unidirectional inductively coupled wireless communications link536. In an embodiment, the exciter antenna528can be up to 1 inch from the receiver antenna506, and offset center-to-center by up to 0.5 inches.

FIG. 9is a block diagram illustrating an embodiment of a wireless battery charging system900in which the wireless battery charging system is configured to measure a received signal strength. Many of the components shown inFIG. 9are similar to the components shown inFIG. 5and, therefore, are identified with the same reference numbers. This embodiment shows the electronic control module102and the electronic lock module106. Also shown are the rechargeable battery108and the electronic door lock110. In one embodiment, the electronic lock module106includes the microprocessor314, the 433 MHz RF transmitter304, 100 kHz receiver502, and the battery charge module310. In one embodiment, the rechargeable battery108supplies power to the electronic door lock110, the microprocessor314, and the 433 MHz transmitter304, via the electronic lock module power supply bus318. The 433 MHz RF transmitter304receives a signal from microprocessor314, and outputs an RF signal at a frequency of 433 MHz. This RF signal is output to RF antenna308for transmission through the unidirectional RF data communications link334. The 100 kHz receiver502is powered by a wireless signal received by solenoid506over unidirectional inductively coupled wireless communications link536. In other embodiments, the unidirectional link536may be comprised of a magnetically coupled link. The unidirectional inductively coupled wireless communications link536is configured to wirelessly transmit both data and a charging signal that is used to recharge the rechargeable battery108.

In one embodiment, the electronic control module102includes microprocessor320, 100 kHz transmitter522, the 433 MHz RF receiver324and host I/O344. In this embodiment, the microprocessor320, the 100 kHz transmitter522, the 433 MHz RF receiver324and the host I/O344are powered from external power supply330via the electronic control module power supply bus332. The 100 kHz transmitter522receives a signal from microprocessor320, and outputs a signal at a frequency of 100 kHz. This 100 kHz signal is output to solenoid528for transmission over the unidirectional inductively coupled wireless communications link536. The 433 MHz RF receiver324receives an RF signal via the RF antenna326over the unidirectional RF data communications link334and outputs this signal to the microprocessor320.

In this embodiment, the unidirectional wireless RF data communications link334and the unidirectional inductively coupled wireless communications link536collectively constitute the bidirectional data link112. Furthermore, the wireless charging link114is implemented by the unidirectional inductively coupled wireless communications link536. Thus, the unidirectional inductively coupled wireless communications link536wirelessly transmits both data and the charging signal from the electronic control module102to the electronic lock module106.

In one embodiment, the microprocessor314in the electronic lock module106periodically monitors the status of the charge on the rechargeable battery108. The microprocessor314transmits this status of the charge on the rechargeable battery108as a data signal to the 433 MHz RF transmitter304, which outputs this data signal to the RF antenna308that is electrically coupled to the 433 MHz RF transmitter304. The RF antenna308transmits the data signal comprising the status of the rechargeable battery108over the unidirectional RF data communications link334. This data signal is received by the RF antenna326electrically coupled to the 433 MHz RF receiver324that is a part of the electronic control module102. The data signal received by the 433 MHz RF receiver324is transmitted to the microprocessor320. The microprocessor320compares the received data signal, which is the status of the charge on the rechargeable battery, with a threshold value.

If the status of the charge on the rechargeable battery is less than the threshold value, the microprocessor320transmits a charging signal to the 100 kHz transmitter522. The 100 kHz transmitter522transmits this charging signal to solenoid528which is electrically coupled to the 100 kHz transmitter522. The solenoid528wirelessly transmits the charging signal over the unidirectional inductively coupled wireless communications link536. The charging signal is wirelessly received by the solenoid506which is electrically coupled to the 100 kHz receiver502. The solenoid506transmits the received charging signal to the 100 kHz receiver302. The charging signal is used to power the 100 kHz receiver502and the battery charge module310, and the charging signal is also transmitted to the battery charge module310, which transmits the charging signal to charge the rechargeable battery108via charging path312. This embodiment implements the non-continuous charging method. In this embodiment, data from the electronic control module102is wirelessly transmitted to the electronic lock module106via the unidirectional inductively coupled wireless communications link536in a non-continuous manner, along with the wirelessly transmitted charging signal.

In another embodiment, the microprocessor320transmits a charging signal to the 100 kHz transmitter522regardless of the status of the charge on the rechargeable battery108. The 100 kHz transmitter522transmits this charging signal to solenoid528which is electrically coupled to the 100 kHz transmitter522. The solenoid528wirelessly transmits the charging signal over the unidirectional inductively coupled wireless communications link536. The charging signal is wirelessly received by the solenoid506which is electrically coupled to the 100 kHz receiver502. The solenoid506transmits the received charging signal to the 100 kHz receiver302. The charging signal is used to power the 100 kHz receiver502and the battery charge module310, and the charging signal is also transmitted to the battery charge module310, which transmits the charging signal to charge the rechargeable battery108via charging path312. This embodiment implements the continuous charging method. In this embodiment, data from the electronic control module102can be wirelessly transmitted to the electronic lock module106via the unidirectional inductively coupled wireless communications link536in a continuous manner, along with the wirelessly transmitted charging signal.

In some embodiments, both solenoids528and506and the associated transmitter522and receiver502are resonant at (i.e., are tuned to) a frequency of 100 kHz. In other embodiments, the resonant frequency may be a frequency different from 100 kHz.

In other embodiments, the door sense module316monitors a status of the door104, such as door open, door ajar, door shut and latch/bolt position sense. The door sense module316periodically transmits a door status data signal to the microprocessor314. This door status data signal is transmitted by the microprocessor314to the 433 MHz RF transmitter304, which then transmits this data signal to RF antenna308that is electrically coupled to the 433 MHz RF transmitter304. The door status data signal is transmitted by the RF antenna308over the unidirectional RF data communications link334. The door status data signal is received by RF antenna326that is electrically coupled to the 433 MHz RF receiver324. RF antenna326transmits the received door status data signal to the 433 MHz RF receiver324, which then transmits the door status data signal to microprocessor320for subsequent processing.

In other embodiments, the electronic lock module106periodically transmits a data signal to the electronic control module102via the unidirectional RF data communications link334. The contents of this data signal include the charge status on the rechargeable battery108and the status of the door. This periodically transmitted data signal may be referred to as a heartbeat signal. In other embodiments, the monitoring of the door status is performed by the electronic control module102.

Electronic control module102is also electrically coupled via an electrical coupling342to credential I/O module340. The credential I/O module340reads an input from a user for authentication purposes. User input methods include, for example, magnetic cards, biometrics, keypads, and smart devices such as smartphones and PDAs that use communication protocols such as Near Field Communication (NFC). The credential I/O module340transmits user input to the electronic control module102for authentication. The credential I/O module340also receives input from the electronic control module102via the electrical coupling342, including user feedback that includes, but is not limited to, audio-visual signals either confirming or denying permission to enter.

In some embodiments, the credential I/O module340is physically attached to the door104and electrically coupled to the electronic lock module106. In this embodiment, the credential I/O module340, powered by rechargeable battery108, reads an input from a user for authentication purposes. The credential I/O module340transmits user input to the electronic control module102for authentication via the unidirectional RF data communications link334. The credential I/O module340also receives input from the electronic control module102via the unidirectional inductively coupled wireless communications link536, including user feedback that includes, but is not limited to, audio-visual signals either confirming or denying permission to enter.

Electronic control module102is also electrically coupled via an electrical coupling338to the access control module328via the host I/O344. The interface between the host I/O344and the access control module328is used for purposes such as user authentication, discussed in greater detail in the description ofFIG. 4. In some embodiments, the electrical coupling338between the host I/O344and the access control module328is realized by standard connectivity methods that include, for example, Ethernet or Wi-Fi.

In some embodiments, 100 kHz receiver502outputs two signals to microprocessor314—an analog signal902and a digital signal904. Analog signal902is a rectified and filtered version of the charging signal, while digital signal904includes the demodulated data encoded onto the charging signal. Microprocessor314receives the demodulated data and processes it accordingly (for example, processing command signals to lock or unlock the door). Microprocessor314also reads in analog signal902. In some embodiments, analog signal902is digitized by an on-chip analog-to-digital converter (ADC) associated with microprocessor314. Microprocessor314processes digitized analog signal902via software-based methods such as signal averaging to determine, for example, the average signal strength. The average signal strength is representative of the signal strength associated with the charging signal as received by 100 kHz receiver502. In some embodiments, the signal strength associated with the charging signal as received by 100 kHz receiver502decreases when the door is open (as compared to a reference signal strength associated with the charging signal as received by 100 kHz receiver502when the door is shut), due to the increased distance between solenoid528and solenoid506, as well as due the associated lack of alignment between solenoid528and solenoid506. This reduction in the signal strength associated with the charging signal as received by 100 kHz receiver502and as determined by microprocessor314can be used as an indicator of a door open condition. This, in turn, can be used for security applications such as triggering alarms if necessary. A detailed description of this functionality is described subsequently.

FIG. 10is an electrical circuit diagram illustrating an embodiment of a portion of a wireless battery charging system1000that includes circuitry associated with receiving a wireless signal. In some embodiments, a portion of the wireless battery charging system1000includes a receiver antenna1002, where receiver antenna1002may be similar in functionality to solenoid506. A half-wave rectifier1010comprised of a diode1006and a filter capacitor1008is electrically coupled to receiver antenna1002. Filter capacitor1008functions to filter and smooth the rectified waveform that is output from diode1006. In some embodiments, half-wave rectifier1010may be replaced with a full-wave rectifier circuit. A Zener diode1014provides overvoltage protection to the circuit. The output of half-wave rectifier1010is similar to analog signal902, and is transmitted via an electrical path1016to battery charge module310and microprocessor314. The output of receiver antenna1002is also electrically coupled to a digital decoder/detector1020, via a parallel capacitor1004and a diode1012, where parallel capacitor1004is a part of a resonant circuit that includes receiver antenna1002and parallel capacitor1004, while diode1012functions as an amplitude modulation (AM) detector, and extracts demodulated data from the received signal. Digital decoder/detector1020receives the demodulated data from diode1012. This demodulated data is digital data. Digital decoder/detector1020processes the digital data, and then transmits this processed digital data to microprocessor314via a digital path1018, where the transmission of the digital data via digital path1018to microprocessor314comprises digital signal904.

FIG. 11is a process flow diagram illustrating a method1100for determining whether a door is open based upon a measurement of received wireless signal strength. An electronic control module associated with a door generates a wireless signal at1102. In some embodiments, the electronic control module may be similar to electronic control module102, and the wireless signal may be similar to the charging signal used to charge rechargeable battery108. At1104, an electronic lock module associated with the door receives the wireless signal. In some embodiments, the electronic lock module may be similar to electronic lock module106. Next, at1106the electronic lock module measures the strength of the received wireless signal. The process of measuring the strength of the received wireless signal may include a combination of hardware and software-based approaches using, for example, the circuitry, the associated microprocessor314and the software program associated with microprocessor314as discussed above in the description ofFIG. 10. In some embodiments, the process of measuring the strength of the received wireless signal includes digitizing the rectified voltage generated along electrical path1016, where the digitization process is done by an analog-to-digital converter (ADC) associated with microprocessor314. In some embodiments, the strength of the received wireless signal is clamped by Zener diode1014. The digitized rectified voltage is then read by microprocessor314, and software processing such as signal averaging may be performed by microprocessor314on the digitized rectified voltage to compute average received signal strength.

At1108, the electronic lock module determines whether the door is open based on the strength of the received wireless signal. In some embodiments, the electronic lock module measures the strength of the received wireless signal when the door is closed. This strength of the received wireless signal is substantially at a maximum value that can be measured by the electronic lock module, as the door closed condition corresponds to maximum alignment between the transmitter antenna and receiver antenna associated with the electronic control module and the electronic lock module respectively. This maximum alignment, in turn, is associated with substantially maximum power transfer associated with the wireless signal. Any deviation from the maximum alignment between the antennas (as associated with, for example, the door being opened) results in a drop in the measured strength of the received wireless signal as received by the electronic lock module. The drop in the measured strength of the received wireless signal is also associated with the increase in the distance between the transmitter antenna and receiver antenna, also associated with (among other things) the door being open. In other words, a drop in the measured strength of the received wireless signal as received by the electronic lock module is associated with the door being open, or some other anomalous condition. Appropriate software running on, for example, microprocessor314can measure the loss in the strength of the received wireless signal and determine whether the door is open. In some embodiments, when the strength of the received wireless signal drops to 80 percent or less of the signal strength associated with the door being closed, the system can determine that the door is open.

FIGS. 12A and 12Btogether form a process flow diagram illustrating a method1200for determining whether a door is open based upon a measurement of received wireless signal strength while also performing security functions. The method1200is a more elaborate description of the method1100. At1202, an electronic control module associated with a door generates a wireless signal. This step is similar to step1102associated with method1100. At1204an electronic lock module associated with the door receives the wireless signal, and at1206the electronic lock module measures the strength of the received wireless signal. At1208, the method checks to see if the strength of the received wireless signal as measured by the electronic lock module is less than a predetermined threshold value. (The predetermined threshold value may be determined, for example, as in the description ofFIG. 11.) In some embodiments, the predetermined threshold value is associated with maximum alignment between the transmitter antenna and the receiver antenna associated with the electronic control module and the electronic lock module respectively. If the strength of the received wireless signal as measured by the electronic lock module is not less than a predetermined threshold value, then the method goes to1210, where it determines that the door is shut. The method then returns to1204.

If, at1208, the method determines that the strength of the received wireless signal is less than the predetermined threshold value, then the method goes to1212, where it determines that the door is open. In some embodiments, at1212the method might initialize a timer to measure the time elapsed since the time the method determines that the door is open. The method then continues to A, with a continued description in the next figure.

FIG. 12Bis a continued description of the method1200fromFIG. 12A. Starting at A, the method1200goes to1214and checks to see if the opening of the door is associated with an authorized user whose credentials have been appropriately authenticated by, for example, the electronic control module, the electronic lock module, or by any other suitable authentication device. If the method determines that the opening of the door is not associated with an authorized user then the method goes to1216, where the electronic lock module engages a door lock associated with the door and activates an alarm to indicate an anomalous door open condition. Another example of an anomalous door open condition is when the door is open without the electronic lock module receiving an authorization from the electronic control module to unlock the door, indicating a possibility that the door might have been forced open. The reengagement of the door lock ensures that the door cannot be reopened once it is shut. The associated alarm may be an audible alarm generated by the electronic lock module or any other type of alarm, warning, or notification. The electronic lock module may also transmit the anomalous door open status to the electronic control module via, for example, unidirectional RF data communications link334.

At1214, if the method determines that the opening of the door is associated with an authorized user whose credentials have been appropriately authenticated, then the method proceeds to1218, where it checks to see if the timer value associated with the timer initialized in1212is greater than a preset threshold, where the preset threshold signifies a time limit for which the door lock remains disengaged. In some embodiments, the time limit is determined by the typical amount of time it would take for a person to open the door after successful authentication. In other embodiments, the electronic lock module can engage the door lock when a door open condition is detected. Using methods like this to set a time limit can be advantageous in ensuring that the door remains unlocked for the minimum required amount of time. This feature is important from a security perspective. At1218, if the timer value is greater than or equal to the preset threshold, the method proceeds to1222, where the door lock is activated by the electronic lock module. At1222the method also stops the timer and resets the timer for the next cycle of operation.

Returning back to1218, if the timer value is less than the preset threshold, then the method goes to1220, where it checks to see whether the door is shut. If the door is not shut, then the method goes back to1218. In some embodiments, the electronic lock module can periodically communicate a door open status to the electronic control module via, for example, unidirectional RF data communications link334. On the other hand, if, at1220, the door is shut then the method proceeds to1222, where the door lock is activated by the electronic lock module. At1222the method also stops the timer and resets the timer for the next cycle of operation.

FIG. 13is a block diagram illustrating an embodiment of a wireless battery charging system1300configured to process information from multiple input sources. In some embodiments, wireless battery charging system includes electronic control module102and electronic lock module106, where electronic control module102and electronic lock module106are configured to communicate via bidirectional data communications link112and wireless charging link114. The operation of this system is as described earlier. Appropriate authentication can be used to ensure that an electronic control module and an electronic lock module comprise a matched set. In other words, a first electronic lock module paired with a first electronic control module will not accept or process information from a second electronic control module and vice versa. Similarly, the first electronic control module will not accept or process information from a second electronic lock module that is not paired with the first electronic control module. This feature allows multiple combinations of matched electronic control modules and electronic lock modules to be used in an environment such as a school. Classrooms can be equipped with such door locking systems that wirelessly recharge the battery associated with the electronic lock module.

In some embodiments, for a matched pair comprising, for example, electronic control module102and electronic lock module106, a third matching device, an auxiliary input source1302, can be configured to transmit data to electronic control module102via a unidirectional wireless data link1304. Auxiliary input source1302can, for example, issue a request to electronic control module102via unidirectional wireless data link1304, where the request may be to lock or unlock the associated door. Electronic control module102may receive this request and perform the necessary action of locking or unlocking the door via a command issued to electronic lock module106via bidirectional data communications link112. One more auxiliary input sources such as auxiliary input source1302may be matched to the matched pair comprising electronic control module102and electronic lock module106. The application of this system may be used for security purposes. For example, in the case of an emergency in school (for example, an active shooter situation), a teacher in possession of an auxiliary input source may issue a command to lock the associated classroom door, thereby preventing anyone from entering the classroom, and hence increasing the security of the classroom.

FIG. 14Ais a front elevational diagram of a ferrite pot core solenoid preform which may be used with one or more embodiments.FIG. 14Bis a side elevational diagram of the ferrite pot core solenoid preform in accordance withFIG. 14Ashowing details of the internal structure of the ferrite pot core preform.

An antenna for transmitting electromagnetic energy for charging is may be formed as a solenoid of wire wrapped around spindle1404of preform1402. Preform1402is formed of a ferrite material and acts to constrain the magnetic flux lines formed by a solenoid formed of wire (not shown) wrapped around spindle1404so that the flux lines preferentially exit the pot core out of its open side1406rather than up, down or out the rear side1408. This is particularly helpful when the material surrounding the pot core comprises metal as is typically the case in mullions of interior and exterior doors of commercial buildings. Without the pot core, more power would be required to achieve the same delivered signal strength to a receiving antenna in the mating door. A similar pot core type antenna may be used on the mating door as an antenna, however, in many cases the door will not comprise metal (e.g., a wooden door) and the interfering effects of the metal with the charging signal will not be as pronounced on the door side. So, while a pot core is particularly helpful on the mullion side of the door/mullion gap, it is less critical on the door side in many circumstances from a technical perspective. The pot core approach, however, does provide a convenient compact antenna which makes for easy installation on both sides of the mullion/door gap and thus may advantageously be used on both sides for that reason.

In one embodiment an RFID access control reader may be integrated with the electronic lock module and mounted therewith as an integrated assembly so that presenting an authorized RFID credential to the access control reader will generate a signal causing the door lock to unlock directly in response to the access control reader sending an unlock command to the electronic lock module.

While exemplary embodiments and applications have been shown and described, it would be apparent to those skilled in the art having the benefit of this disclosure that numerous modifications, variations and adaptations not specifically mentioned above may be made to the various exemplary embodiments described herein without departing from the scope of the invention which is defined by the appended claims.