System and method for optimizing electronic key backup functionality

Abstract

A key fob includes at least one wireless communication circuit, a power source node coupled to provide power to the at least one wireless communication circuit, a battery node, a battery power circuit, and an inductive power circuit. The battery power circuit provides power when a battery having sufficient charge is provided. The inductive power circuit provides power only when energized with an inductive power source and when the battery is not provided or is not sufficiently charged. The inductive power circuit can include a rectifier circuit and an inductor, and can additionally include regulator circuitry. The inductive power circuit does not perform wireless communication, thereby simplifying the circuitry and operation of the key fob and corresponding access system. Since the inductive power circuit is configured only to transfer power, the inductive power circuit can be optimized for power transfer. The access system inductively couples power to the key fob when located within a predetermined coupling zone distance.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to an electronic control key, and more particularly to a system and method for optimized electronic control key or "key fob" backup functionality. BACKGROUND

[0002] An electronic control key or "key fob" is a keyless entry remote device that can be used to perform one or more authorized functions such as locking or unlocking a door to control access to a vehicle or other controlled location (e.g., hotel room, apartment, building, secure area, etc.), opening a trunk, activating an alarm, starting an engine, etc. Modern key fobs can include wireless communication technologies such as 5G, Wi-Fi, Bluetooth, Bluetooth Low Energy (BLE), etc. to communicate with a corresponding access control system at a vehicle or other secure location. The key fob and access control system can include additional wireless technologies such as Ultra-Wideband (UWB) to perform a secure distance measurement such as a proximity determination between the key fob and the access control system. UWB devices can be used, for example, to determine when the key fob is within a predetermined threshold distance to facilitate an access or other control decision. The key fob typically includes a battery that provides power for the wireless communication devices. The term "key fob" as used herein contemplates many different configurations of electronic control devices including traditional vehicle key fob devices and various other electronic smart device configurations such as a SmartFOB, smart card, smart watch, mobile or cellular phone, etc.

[0003] When the battery of a key fob is depleted or otherwise disconnected, the primary communication circuitry of the key fob that is powered by the battery can be disabled or otherwise unavailable. For this reason, the key fob can include a remotely powered and controlled backup communication circuitry. The backup communication circuitry can be independent and secure such that it independently performs the same functions and applications of the primary communication circuitry including secure password and key storage functions. An inductive element can be provided on the key fob that inductively links with an access control system to establish an inductive power source and communication link. For example, existing automotive systems can use low frequency (LF) technology in which the length of the cable to a central base station is critical, or near field communication (NFC) technology in which reader electronics are integrated into each coupled device.

[0004] There are several problems with current and proposed backup communication devices. The backup communication device must include its own microcontroller and flash memory and must be self- contained in order to be able to execute the full set of applications of the primary communication device. In addition, each of the communication nodes, including the respective circuitry in the primary communication circuit, the backup communication circuit, and the access control system, are classified as radio equipment that requires relevant compliance testing and certification. The resulting key fob is relatively complex, expensive to manufacture, and requires a significant amount of development time to design and implement the appropriate functionality of each microcontroller for each individual communication interface, including, for example, wake-up, connection, communication for transmitting information, safety distance check, etc. The backup communication device of the inductive link typically must perform all of these functions except the safety distance check. SUMMARY

[0005] According to one aspect of the application, there is provided a key fob, comprising:

[0006] at least one wireless communication circuit;

[0007] a power node coupled to provide power to the at least one wireless communication circuit;

[0008] a battery node;

[0009] a battery power circuit to provide power via the power node when a battery having sufficient charge is coupled to the battery node; and

[0010] an inductive power circuit to provide power via the power node only when powered with an inductive power source and when the battery node does not provide power.

[0011] According to one or more embodiments, the inductive power circuit comprises a rectifier circuit and an inductor.

[0012] According to one or more embodiments, the rectifier circuit comprises a full wave rectifier.

[0013] According to one or more embodiments, the inductive power circuit further comprises regulator circuitry coupled to the power node.

[0014] According to one or more embodiments, the inductive power circuit is not configured to perform wireless communication.

[0015] According to one or more embodiments, the inductive power circuit is optimized for inductive power transfer.

[0016] According to one or more embodiments, the at least one wireless communication circuit comprises a Bluetooth radio circuit.

[0017] According to one or more embodiments, the at least one wireless communication circuit comprises ultra-wideband wireless circuitry.

[0018] According to one or more embodiments, the at least one wireless communication circuit of the key fob provides an indication to the inductive power circuit during a communication session to maintain power.

[0019] According to a second aspect of the application, there is provided a key fob system, comprising:

[0020] a key fob, comprising:

[0021] at least one wireless communication circuit;

[0022] a power node coupled to provide power to the at least one wireless communication circuit;

[0023] a battery node;

[0024] a battery power circuit to provide power via the power node when a battery having sufficient charge is coupled to the battery node; and

[0025] an inductive power circuit to provide power via the power node only when energized with an inductive power source and when the battery node does not provide power; and

[0026] an access system comprising an inductive power generator capable of inductively coupling to the inductive power circuit of the key fob when the inductive power circuit is within a predetermined coupling zone distance of the inductive power generator.

[0027] According to one or more embodiments, the access system additionally comprises:

[0028] an access controller comprising at least one wireless communication circuit;

[0029] a sensor to sense a presence and report the presence to the access controller; and

[0030] wherein upon detection of the presence, the inductive power generator is activated and the access controller attempts to establish wireless communication with the key fob.

[0031] According to one or more embodiments, upon indication by the key fob of activation of the inductive power generator following establishment of wireless communication, the access controller maintains the activation.

[0032] According to one or more embodiments, the access controller and the key fob wirelessly communicate with each other according to Bluetooth.

[0033] According to one or more embodiments, the access controller and the key fob each include wireless Bluetooth communication circuitry and wireless ultra-wideband communication circuitry.

[0034] According to one or more embodiments, the sensor includes a button.

[0035] According to one or more embodiments, the sensor includes a capacitive sensor.

[0036] According to one or more embodiments, the inductive power supply circuit includes a rectifier circuit and an inductor.

[0037] According to one or more embodiments, the inductive power supply circuit additionally includes regulation circuitry coupled to the power supply node.

[0038] According to one or more embodiments, the inductive power supply circuit and the inductive power supply generator are not configured to perform wireless communication.

[0039] According to one or more embodiments, the inductive power supply circuit is optimized for inductive power transfer. BRIEF DESCRIPTION OF DRAWINGS

[0040] Embodiments of the invention are illustrated by way of example, and not limitation, in the figures of the accompanying drawings in which like references indicate similar elements. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale.

[0041] Figure 1 is a simplified block diagram of a key-based access system implemented in accordance with one embodiment of the present disclosure.

[0042] Figure 2 is a simplified schematic block diagram of circuitry of a key fob of Figure 1 in accordance with one embodiment of the present disclosure.

[0043] Figure 3 is a flowchart illustrating operation of circuitry of a vehicle including Figure 1 an access controller, a sensor, and an IPG in accordance with one embodiment of the present disclosure.

[0044] Figure 4 is a flowchart illustrating operation of circuitry of a key fob of Figure 1 in accordance with one embodiment of the present disclosure during an inductive link. DETAILED DESCRIPTION

[0045] The present inventors have recognized that there is a need to provide a backup function for an electronically controlled key (also referred to as a “key fob”) that is powered by a battery when the battery is not present, disconnected, or otherwise unavailable (e.g., depleted or substantially discharged). Accordingly, a system and method have been developed to optimize a key fob backup function that includes an inductive link that powers the primary circuitry of the key fob but does not perform communications.

[0046] Figure 1 is a simplified block diagram of an electronic key-based control system 100 implemented in accordance with one embodiment of the present disclosure. An electronically controlled key or key fob 102 is configured to establish an authorized wireless communication with an access controller 104 contained within a vehicle 106, such as a car, truck, SUV, van, etc. The vehicle 106 can also represent any type of controlled location, such as a hotel room, apartment, building, secure area, etc. The key fob 102 can be used to perform a variety of different functions, such as lock / unlock doors, open a trunk, activate an alarm, start the engine of the vehicle 106, etc. The key fob 102 and the access controller 104 can each be equipped with wireless communication circuitry configured to wirelessly communicate with one another to perform wake-up, connection, and communication tasks for access, control, and data transfer functions, etc., as well as to perform distance measurements between the key fob 102 and the vehicle 106.

[0047] As shown, the key fob and the access controller each include a communication (COM) antenna coupled to internal communication circuitry to perform primary communications. In one embodiment, for example, the key fob and the access controller can each include a wireless Bluetooth device configured to operate in accordance with a Bluetooth wireless standard including a low power version such as Bluetooth Low Energy (BLE). Although Bluetooth and BLE are commonly used for such functions, alternative wireless communication technologies such as 5G or Wi-Fi are also contemplated for performing the same or similar functions. In addition, the key fob 102 and the access controller 104 can each be equipped with additional wireless communication circuitry configured to wirelessly communicate with one another to perform distance (DIST) measurements, etc., for positioning functions including determining the relative proximity of the key fob 102. As shown, for example, the key fob and the access controller each include a distance antenna DIST coupled to internal communication circuitry to perform wireless communications associated with measuring the distance between the key fob 102 and the access controller 104. In one embodiment, for example, the key fob and the access controller can each include an Ultra-Wide Band (UWB) device configured to operate using UWB technology.

[0048] During normal operation, the key fob 102 can be used to perform any of one or more different authorized functions, such as locking / unlocking the vehicle, opening the trunk, activating the alarm system, starting the engine of the vehicle 106, etc. Many of these authorized functions can be activated by one or more button presses on other interfaces (not shown) provided on the key fob 102. Other authorized functions can be performed without human intervention, such as passive keyless entry (PKE). When the key fob 102 is located within a predetermined threshold distance 101 from the vehicle 106, an authorized wireless communication session can be established to allow wireless communication between the key fob 102 and the access controller 104 to perform any of the desired authorized functions. The threshold distance 101 is predetermined to ensure that the key fob 102 is in the vicinity of the vehicle 106 to enable the authorized functions. In one embodiment, the predetermined threshold distance 101 is on the order of a few meters, such as 2-3 meters, etc., although any suitable distance threshold less than or greater than 2-3 meters is contemplated. The key fob 102 can include a memory or the like that stores a security key or code that can be encrypted and transmitted for authentication purposes. The COM and DIST functions are supported by corresponding communication circuitry powered by a battery or the like, which is further described below.

[0049] When the battery of the key fob 102 is absent, disconnected, or depleted (or substantially discharged), then normal wireless communication including the COM and DIST functions can be disabled for other reasons, as is the case with original or conventional key fob configurations. The key fob 102 includes an inductive element 103 that can be used to establish an inductive link with a corresponding inductive element 105 located on or in the vehicle 106. The inductive element 103 and the inductive element 105 can each be implemented as a physical inductor, although alternative inductive configurations are contemplated. When the inductive element 103 and the inductive element 105 are close enough to each other, such as within a predetermined coupling zone 108, then an inductive link can be established to transfer power and energize the circuitry of the key fob 102. In one embodiment, the location of the inductive element 105 of the vehicle 106 is marked by the user or otherwise known, such as at or near a door handle, etc. The coupling zone 108 can be a predetermined distance, such as 5-8 centimeters (or 2-3 inches), etc. The user places the key fob 102 such that the inductive element 103 of the key fob 102 is within the coupling zone 108 of the inductive element 105.

[0050] Various methods for detecting the presence of the key fob 102 are contemplated. In the illustrated embodiment, a sensor 110 is disposed on or within the vehicle 106. The sensor 110 can be configured according to any suitable method, and can include a sensor interface 107 configured according to the particular sensor type. The sensor interface 107 can be a button, an inductive object detector, a capacitive sensor, etc. In one embodiment, the sensor interface 107 can be close enough to the inductive element 105 to detect the inductive element 103 when located within the coupling region 108. In another embodiment, the sensor interface 107 is a button that is pressed by the user. In yet another embodiment, the sensor interface 107 can be a touchpad or the like configured as a capacitive sensor. In yet another embodiment, no sensor 110 is employed, and the inductive element 105 itself can serve as the sensing device. Once the proximity indicative of a possible inductive link is detected, the sensor 110 wakes up or otherwise activates the access controller 104. The sensor 110 or the access controller 104 activates an inductive power supply generator (IPG) 112 that is electrically connected to the inductive element 105. Upon activation, the IPG 112 energizes the inductive element 105 to transfer power to the inductive element 103 of the key fob 102. As described further herein, once the inductive element 105 is energized, the primary wireless communication (COM) of the key fob 102 is powered to enable normal wireless communication to begin.

[0051] In one embodiment, only limited circuitry of the key fob 102 is energized by the inductive link, e.g., only the COM functionality. In this limited activation embodiment, the DIST communication can remain disabled since the distance of the key fob 102 is not required to be measured, as the key fob 102 is assumed to be located within the coupling region 108 a distance much less than the threshold distance 101. In another embodiment, the entire circuitry of the key fob 102 can be energized by the inductive link.

[0052] Figure 2is a simplified schematic block diagram of the circuitry of a key fob 102 according to one embodiment of the present disclosure. The circuitry includes COM circuitry 202, DIST circuitry 204, and MEMS circuitry 206. The COM circuitry 202 establishes primary wireless communication with the corresponding COM circuitry (not shown) of the access controller 104, which is otherwise referred to as “authorized” communication. In the illustrated embodiment, COM is the primary method of communication between the key fob 102 and the access controller 104, but alternative wireless communication technologies are contemplated. The DIST circuitry 204 operates according to a suitable wireless technology to perform distance measurements for locating the key fob 102. It should be noted that the COM and DIST circuitry of the key fob 102 can be combined into a single wireless communication device that performs both functions. However, when BLE or the like is used to perform the COM function, BLE can not be able to perform proper localization in a target environment at an acceptable speed, whereby UWB circuitry or the like is more suitable for the DIST function.

[0053] The MEMS circuitry 206 can be used for various purposes, including energy conservation, etc. The key fob circuitry additionally includes a battery 208 having a negative terminal coupled to ground (GND) and a positive terminal coupled to an anode of a power diode 210, the cathode of which is coupled to a power supply node 212 that produces a supply voltage VDD. The power supply node 212 is coupled to the power inputs of the COM circuitry 202, the DIST circuitry 204, and the MEMS circuitry 206. A communication bus 214 is provided to enable internal communication between the COM circuitry 202, the DIST circuitry 204, and the MEMS circuitry 206, and the communication bus 214 can be implemented in any suitable manner, such as by a serial peripheral interface (SPI) or the like. A COM antenna 216 is coupled to the COM circuitry 202 and a DIST antenna 218 is coupled to the DIST circuitry 204, but a single antenna is contemplated in different embodiments.

[0054] The circuitry of the key fob 102 additionally includes an inductive power supply circuit 220. The inductive power supply circuit 220 includes an LC tank circuit 222, a rectifier circuit 224, and a regulator circuit 225. The LC tank circuit 222 includes the inductive element 103 shown as an inductor and a filter capacitor CI. The inductive element 103 has a first end coupled at a first node 226 to a first end of CI, and has a second end coupled at a second node 228 to a second end of CI. The rectifier circuit 224 includes four diodes Dl, D2, D3, and D4 coupled in a bridge configuration. Node 226 is coupled to the cathode of Dl and the anode of D2, and node 228 is coupled to the cathode of D3 and the anode of D4. The anodes of Dl and D3 are coupled to GND, and the cathodes of D2 and D4 are coupled to a node 230. The shown regulator circuitry 230 is coupled between node 230 and the power supply node 212, and can be labeled as GND. A filter capacitor C2 is coupled between node 230 and GND.

[0055] In one embodiment, the regulator circuitry 225 can simply be a Zener diode or voltage limiter, etc., coupled between node 230 and GND for limiting the voltage of VDD to a predetermined voltage level, in which case node 230 can be directly coupled to (or otherwise identical to) the power supply node 212. Alternative voltage limiting or voltage protection or regulator devices or circuits are contemplated, such as a low-dropout (LDO) regulator or a DC-DC regulator, to convert or limit the voltage generated on node 230 to limit VDD to a desired voltage level or within a desired voltage range.

[0056] In Figure 2 In operation of the shown circuitry of the key fob 102, when the battery 208 is present and sufficiently charged for battery operation, the battery voltage forward biases the power diode 210 and charges the supply voltage VDD to provide power to the COM circuitry 202, the DIST circuitry 204, and the MEMS circuitry 206 for normal operation. When the battery 208 is not present, disconnected, or otherwise not functioning (e.g., depleted or substantially discharged), and the inductive element 103 and the inductive element 105 are located within the coupling region 108 establishing an inductive link, and when the IPG 112 is activated to energize the inductive element 105 with an alternating current (AC) of the inductive power mode, a corresponding AC current flows through the inductive element 103, generating an AC voltage between node 226 and node 228. The AC voltage is full-wave rectified by the rectifier circuit 224 and filtered by the capacitor CI to generate a corresponding voltage on node 230. The regulator 230 limits or converts the voltage to a desired voltage level of the supply voltage VDD. The COM circuitry 202 is not provided separately as a backup communication via the inductive link, but is powered to enable primary wireless communication with the access controller 104.

[0057] In one embodiment of the inductive power mode, the DIST circuitry 204 and the MEMS circuitry 206 are disabled to conserve energy for the COM circuitry 202. In another embodiment of the inductive power mode, only the DIST circuitry 204 is disabled, and the MEMS circuitry 206 is enabled. In yet another embodiment of the inductive power mode, the COM circuitry 202, the DIST circuitry 204, and the MEMS circuitry 206 are enabled. It should be noted that during the inductive power mode, the distance measurement function of the DIST circuitry 204 can be considered redundant and unnecessary when the inductive elements 103 and 105 are inductively linked. Additionally, it should be noted that any motion sensor function of the MEMS circuitry 206 can be considered redundant and unnecessary during the inductive power mode when the inductive elements 103 and 105 are inductively linked.

[0058] In any case, the inductive link formed by the inductive elements 103 and 105 is used only for the purpose of transferring power from the IPG 112 to the circuitry of the key fob 102 using the inductive power circuit 220, and not for communication purposes. Although the key fob 102 can include additional circuitry not shown, such as battery charging circuitry for charging the battery 208 via the inductive link, in any case the inductive link is not used for communication purposes. In this way, a separate safety backup communication means is eliminated, substantially simplifying the circuitry of the key fob 102. There is no need for a separate microcontroller and corresponding memory to support the functions of the backup communication configuration. Furthermore, since it is used only for power transfer functions, the inductive link does not need to be classified as a radio requiring related compliance testing and certification, reducing the effort for compliance testing (radio compliance) and certification. Additionally, since there is no data communication on the inductive link, there is no modulation, so the system can be tuned for highest efficiency, such as high Q factor, etc.

[0059] Figure 3is a flowchart showing the operation of the circuitry of the vehicle 106 including the access controller 104, the sensor 110, and the IPG 112, according to one embodiment of the present disclosure. The operation begins at block 302 with performing a presence query. The presence query is performed by the sensor 110, depending on the particular configuration of the sensor. When the sensor interface 107 is configured as a button and the button is pressed by a user, then the presence is true. When the sensor interface 107 is configured as a capacitive sensor configuration and when a user is in proximity to or touches the sensor interface 107, then the presence is true. When the sensor interface 107 is configured as an inductive object load detector and when the inductive element 103 (or any similar inductive element or device) is in sufficient proximity to the sensor interface 107, then the presence is true. When the presence is false, the operation loops back to block 302, indicating that the sensor 110 is monitored.

[0060] When the presence is true, the operation proceeds to block 304, where the sensor 110 wakes up the access controller 104, and the sensor 110 or the awakened access controller 104 subsequently activates the IPG 112. If the key fob 102 is present and linked inductively, then activation of the IPG 112 provides power to the circuitry of the key fob 102, as previously described. At the next block 306, a query is made as to whether an authorized communication (AUTH.COMM) is established with the key fob 102. In one embodiment, the AUTH.COMM is established between the COM circuitry 202 of the key fob 102 and the corresponding COM circuitry within the access controller 104. When the key fob 102 is powered on or otherwise awakened, an attempt is made to establish a communication session with the access controller 104. At block 306, the access controller 104 determines whether the key fob 102 is authorized, for example, detecting the correct key or code value. If the key fob 102 is not present, or if the nearby device or entity that triggered the presence is not an authorized device, for example, a different or unauthorized key fob, or simply a nearby foreign inductive or capacitive element or accidental pressing of the sensor button, then the operation proceeds to block 308, where the IPG 112 is deactivated, and the operation loops back to block 302. It should be noted that a timeout function can be implemented to deactivate the IPG 112 to prevent damage to foreign objects.

[0061] If the remote key 102 is present and an authorized communication session is established, the operation proceeds to block 310 to query whether the IPG 112 is required to provide power. For normal operation with the battery 208 present and charged, the operation proceeds to block 312 where the IPG 112 is deactivated, each normal operation completes the communication session, and the operation is complete. On the other hand, if the IPG 112 is required to provide power to the remote key 102, the operation proceeds to block 314 where the IPG 112 remains active to complete the communication session. When the communication session is complete, the operation proceeds to block 316 to deactivate the IPG 112, and the operation is complete. In one embodiment, during the authorized communication, the remote key 102 informs the access controller 104 whether the IPG 112 is required, for example, by setting a bit in a register or control field, or by sending an instruction or command, or the like. In another embodiment, the IPG 112 can sense power consumption via the inductive element 105, and if an authorized communication is established with the remote key 102, it is considered that the IPG 112 must provide power to the remote key 102.

[0062] Figure 4is a flowchart showing operation of the circuitry of a key fob 102 according to one embodiment of the disclosure during an inductive link. In this case, the battery power from the battery 208 is not available (disconnected, not present, discharged), and an inductive link is established. When the key fob 102 is powered on, operation proceeds to block 402 to inquire whether power is provided by the inductive link of the inductive power circuit 220 alone. Although not shown explicitly, additional detection circuitry such as a battery detector or an inductive field detector provides an indication to the COM circuitry 202 as to the source of power within the key fob 102, e.g., from the battery 208 or the inductive power circuit 220. If the inductive link does not provide power, the battery 208 is available, making normal operation applicable. In this case, the functionality of inductive coupling is not applicable, and the operation loops at block 402. If power is provided by the inductive link alone, operation proceeds to block 404, where the COM circuitry 202 attempts to establish an authorized communication with the COM circuitry of the access controller 104. Assuming that an authorized communication is established as determined at the next inquiry block 406, operation proceeds to block 408, where a communication session is completed while maintaining activation of the IPG 112. In one embodiment, the key fob 102 commands or otherwise indicates whether the IPG 112 is needed. In another embodiment, the power via the inductive link is detected by the IPG 112, which communicates the need to remain activated to the access controller 104. Then, after the communication is completed, the circuitry of the key fob 102 returns to sleep. Referring back to block 406, if an authorized communication is not established with the access controller 104, power can be provided by another device without the access controller 104, and the circuitry of the key fob 102 returns to sleep.

[0063] A key fob according to one embodiment includes at least one wireless communication circuit, a power source node coupled to provide power to the at least one wireless communication circuit, a battery node, a battery power circuit, and an inductive power circuit for providing power only. The battery power circuit provides power when a battery having sufficient charge is provided. The inductive power circuit provides power when powered with an inductive power source and when the battery is not provided or is not sufficiently charged, wherein the inductive power circuit does not perform wireless communication, simplifying the circuitry and operation of the key fob and a corresponding access system. The inductive power circuit can include a rectifier circuit and an inductor, and can additionally include regulator circuitry. Since the inductive power circuit is configured to transfer power only, the inductive power circuit can be optimized for power transfer. The access system inductively provides power to the key fob when located within a predetermined coupling distance.

[0064] Although the application has been described in connection with several embodiments, it is not intended to be limited to the particular forms set forth. Rather, it is intended to cover such alternatives, modifications, and equivalents as can be reasonably included within the scope of the application as defined by the appended claims. For example, changes in logical or physical placement of the elements of the various embodiments can be used, where the application is not limited to a particular logical or physical arrangement, device type, or voltage level, etc. For example, logic states such as logic low and logic high can be inverted depending on whether pins or signals are implemented in positive logic or negative logic, etc. In some cases, logic states can be programmable, where the logic state can be inverted for a given logic function.

[0065] As used herein, the terms "a" or "an" are defined as one or more than one. Also, the use of introductory phrases such as "at least one" and "one or more" in the claims should not be construed to imply that the opening limit of any of the marked claim elements is more than one, and that the amounts for each said element can not be individually introduced into the claims using the phrases "at least one" and "one or more," even if the same claim contains the introductory phrases "one" or "an" followed by the introductory phrases "at least one" and "one or more." Similarly, it is to be understood that the terms "first" and "second" are used to arbitrarily distinguish one element from another element without necessarily implying any time or other priority.

Claims

1. A key fob system, characterized by, including: a remote key and access system; the remote key including: at least one wireless communication circuit; a power node coupled to provide power to the at least one wireless communication circuit; a battery node; a battery power circuit to provide power via the power node when a battery having sufficient charge is coupled to the battery node; and an inductive power circuit to provide power via the power node only when powered with an inductive power source and when the battery node does not provide power; the access system including: an inductive power generator capable of inductively coupling to the inductive power circuit of the remote key when the inductive power circuit is within a predetermined coupling zone distance of the inductive power generator; an access controller including at least one wireless communication circuit; a sensor to sense a presence and report the presence to the access controller; and wherein upon detection of the presence, the inductive power generator is activated and the access controller attempts to establish wireless communication with the remote key.

2. The key fob system of claim 1, wherein, the inductive power circuit includes a rectifier circuit and an inductor.

3. The key fob system of claim 2, wherein, the rectifier circuit includes a full wave rectifier.

4. The key fob system of claim 2, wherein, the inductive power circuit additionally includes regulator circuitry coupled to the power node.

5. The key fob system of claim 1, wherein, the inductive power circuit is not configured to perform wireless communication.

6. The key fob system of claim 1, wherein, the inductive power circuit is optimized for inductive power transfer.

7. The key fob system of claim 1, wherein, the at least one wireless communication circuit includes a Bluetooth radio.

8. The key fob system of claim 1, wherein, the at least one wireless communication circuit includes an ultra-wideband radio.

9. The key fob system of claim 1, wherein, the at least one wireless communication circuit of the remote key provides an indication to the inductive power circuit to maintain power during a communication session.

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