Electronic lock and key assembly

[0001] This application is related to, and claims priority from, U.S. Provisional Patent Application No. 60/888,282, filed Feb. 5, 2007 and U.S. Provisional Patent Application No. 60/825,665, filed Sep. 14, 2006, the entireties of which are expressly incorporated by reference herein and made a part of the present specification.

[0002] 1. Field of the Invention

[0003] The present invention generally relates to lock and key assemblies. More specifically, the present invention relates to an improved electronic lock and key assembly.

[0004] 2. Description of the Related Art

[0005] Electronic locks have a number of advantages over normal mechanical locks. For example, electronic locks may be encrypted so that only a key carrying the correct code will operate the lock. In addition, an electronic lock may contain a microprocessor so that, for example, a record can be kept of who has operated the lock during a certain time period or so that the lock is only operable at certain times. An electronic lock may also have the advantage that, if a key is lost, the lock may be reprogrammed to prevent the risk of a security breach and to avoid the expense associated with replacement of the entire lock.

[0006] One drawback of certain electronic locks is that they use a power supply to function properly. Typically, locks of this type are unable to use conventional alternating current (AC) power supplies, such as from wall outlets, due to the inherit lack of security and mobility of such power supplies. Batteries may be used instead, but batteries require constant replacement or recharging. If a battery dies, a lock might fail to function and thereby create a significant security risk. Electromagnets may also be employed, but the bulk of such devices in some instances limits the potential use of electronic locks to larger-scale applications.

[0007] One solution to these drawbacks is to place a power source such as a battery in the key instead of in the lock. This arrangement allows the lock to remain locked even in the absence of a power supply. Placing a battery in the key also allows the battery to be charged more easily because keys are generally more portable than locks.

[0008] When batteries are used in the key, electrical contacts are typically employed to transfer power and data from the key to the lock. However, electrical contacts suffer from the drawback of being susceptible to corrosion, potentially leading to failure of either the key or the lock. Moreover, if separate inductors are used instead to transfer both power and data, magnetic interference between the inductors can corrupt the data and disrupt power flow to the lock.

[0009] Various embodiments of the present invention overcome these problems by providing a key having a power coil and a data coil and an electronic lock having a power coil and a data coil. When the key engages the lock, the power coils preferably are coaxial and the data coils are substantially parallel to one another. This configuration allows at least a portion of a magnetic field induced by the power coils to be substantially orthogonal to a magnetic field induced by the data coils. Because orthogonal magnetic fields have little effect on one another, inductors or other coils may be used in place of electrical contacts with minimal interference between power and data signals.

[0010] A preferred embodiment is, a locking device including a key which includes a key power coil and a key data coil. The locking device also includes an electronically-actuatable lock which includes a lock power coil and a lock data coil. The key power coil and the lock power coil are coaxial and at least partially overlap one another when the key engages the lock. The key data coil lies in a first plane, the lock data coil lies in a second plane. The first plane and the second plane are substantially parallel to one another.

[0011] Another preferred embodiment is a locking device including a key which includes a key power coil and a key data coil. The locking device also includes an electronically-actuatable lock which includes a lock power coil and a lock data coil. The key power coil and the lock power coil are inductively coupled when the key engages the lock. The key data coil and the lock data coil are inductively coupled when the key engages the lock. At least a portion of a data magnetic field created by inductively coupling the lock data coil and the key data coil is substantially orthogonal to a power coil magnetic field created by inductively coupling the lock power coil and the key power coil.

[0012] Yet another preferred embodiment is a method for communicating with an electronic lock. The method includes inductively coupling a key power coil with a lock power coil. The method also includes inductively coupling a key data coil with a lock data coil, such that at least a portion of a power magnetic field generated by inductive coupling of the key power coil and the lock power coil is substantially orthogonal to at least a portion of a data magnetic field generated by inductive coupling of the key data coil and the lock data coil. The method further includes transmitting data between the key data coil and the lock data coil. The data is operative to move a lock to an unlocked position.

[0027] In the description below certain relative terms such as top, bottom, left, right, front and back are used to describe the relationship between certain components or features of the illustrated embodiments. Such relative terms are provided as a matter of convenience in describing the illustrated embodiments and are not intended to limit the scope of the technology discussed below.

Overview of the Key and Lock System

[0028] FIGS. 1 and 2 illustrate one preferred embodiment of an electronic lock and key system, which is generally referred to by the reference numeral 10. The electronic lock and key system 10 includes a lock 100 and a key 200, which are configured to engage one another and to selectively move the key 200 between a locked position and an unlocked position. The lock and key system 10 may be used to permit access to a location or enclosure in a variety of applications, such as a cabinet or other such storage compartment, for example, which may store valuable contents. Certain features, aspects and advantages of the lock and key system 10 may be applied to other types of lock applications, such as selectively permitting access to buildings or automobiles, for example, or for selectively permitting operation of a device. Thus, although the present lock and key system 10 is disclosed herein in the context of a cabinet or storage compartment application, the technology disclosed herein may be used with, or adapted for use with, other suitable lock applications, as well.

[0029] The illustrated electronic lock and key system 10 is configured to use electronic means to verify the identity of the key and to actuate the internal mechanism of the lock 100. When the key 200 engages the lock 100, data transfer and power transfer is enabled between the lock 100 and the key 200. The lock 100 is then preferably permitted to be actuated by the key 200 to move from a locked position to an unlocked position and permit access to the space or location secured by the lock 100. In the illustrated arrangement, the direction of power transfer preferably is from the key 200 to the lock 100, as is described in greater detail below. However, in alternative arrangements, the direction of power transfer may be reversed or may occur in both directions.

[0030] The illustrated lock 100 is preferably used in a cabinet, or other such storage compartment, and is configured to selectively secure a drawer or door of the cabinet relative to a body of the cabinet. However, as will be appreciated, the lock 100 may be used in, or adapted for use in, a variety of other applications. The lock 100 is preferably mounted to the cabinet in such a way so as to allow only a front portion of the lock 100 to be accessible when the cabinet is closed. The lock 100 includes an outer housing 102 with a cylinder 104 that is rotatable within the outer housing 102 when actuated by the key 200. An exposed end of the cylinder 104 is configured to support a lock tab (not shown). The lock tab is configured to cooperate with a stop. The lock 100 is associated with one of the drawer (or door) of the cabinet and the cabinet body, and the stop is associated with the other of the drawer (or door) of the cabinet and the cabinet body. The lock tab rotates with the lock cylinder 104 to move between a locked position, wherein the lock tab mechanically interferes with the stop, to an unlocked position, wherein the lock tab does not interfere with the stop. Such an arrangement is well-known to one of skill in the art. In addition, other suitable locking arrangements may be utilized.

Mechanical Aspects of the Key and Lock System

[0031] FIGS. 3 and 4 illustrate a cross-sectional view of the lock 100 of the electronic lock and key assembly 10 of FIGS. 1 and 2. With additional reference to the FIGS. 3 and 4, the portion of the lock 100 on the left hand side of the FIGs. will be referred to as the front of the lock and the portion on the right hand side of the FIGs. will be referred to as the rear or back of the lock 100. As described above, the lock 100 includes the housing 102 and the cylinder 104. The cylinder 104 is configured to be rotatable within the housing 102 by the key 200 when the lock 100 and the key 200 are properly engaged. The lock 100 further includes a cartridge 106, which includes a mechanism configured to selectively permit the cylinder 104 to rotate within the housing 102. The lock 100 further includes a mating portion 108 which is configured to mate with the key 200 and an attack guard portion 110 which is configured to protect the lock from unwanted tampering.

[0032] The housing 102 of the lock 100 preferably is a generally cylindrical tube with a head portion 112 and a body portion 114. The diameter of the head portion 112 is larger than the diameter of the body portion 114 such that the head portion 112 forms a flange of the housing 102. The head portion 112 also includes an annular groove 174 or key recess. Axially-extending slots 176 open into the annular groove 174 (FIG. 2). The groove 174 and slots 176 are used in engaging the key 200 with the lock 100 and are described in greater detail below. The head portion 112 is further configured to house a seal member, such as an O-ring 116, which is positioned to create a seal between the housing 102 and the cylinder 104. Thus, the lock 100 is suitable for use in wet environments.

[0033] The lock housing 102 also includes a body portion 114 which extends rearwardly away from the head portion 112. The rearward end of the body portion further includes a threaded outer surface 115 which is configured to receive a nut (not shown). The nut is used to secure the lock 100 to a cabinet or other storage compartment. The body portion 114 also includes at least one, and preferably a pair of opposed flattened surfaces 113 or “flats” (FIG. 2, only one shown), which are provided to reduce the likelihood of rotation of the housing 102 in a storage container wall or door. Alternatively, other mechanisms may be used to inhibit rotation of the housing 102 other than the flattened surfaces 113, as will be apparent to one of skill in the art.

[0034] With continued reference to FIGS. 3 and 4, the body portion 114 further includes an internal groove 120 configured to secure the lock cylinder 104 from rotation relative to the lock housing 112 when the lock 100 is in a locked position. The groove 120 preferably is open towards an interior passage 121 of the body portion 114, which houses a portion of the lock cylinder 104. The groove 120 extends axially along the body portion 114 and is formed partially through a thickness of the body portion 114 in a radial direction.

[0035] The body portion 114 further includes a tab 122 that extends slightly rearward from the rearward end of the body portion 114. The tab 122 acts as a stop to limit the rotation of a lock tab (not shown) secured to the cylinder 104.

[0036] The housing 102 is further configured to include a break-away feature incorporated into the structure of the housing 102. The head portion 112 is formed with the body portion 114 in such a way that if someone attempted to twist the housing 102 of the lock 100 by grasping the head portion 112, the head portion 112 is capable of breaking free of the body portion 114, preferably at a location near the intersection of the head portion 112 and the body portion 114 of the housing 102. This feature is advantageous in that it increases the difficulty of opening or disabling the lock 100 by grasping the housing 102. That is, if a person were to attempt to grasp the head portion 112 and it were to break away then there would no longer be an easily graspable surface with which to try to rotate the lock 100 mechanically, without use of the key 200, because the head portion 112, which is external to the cabinet, would no longer be coupled to the body portion 114, which is internal to the cabinet. The break-away feature between the head portion 112 and the body portion 114 may be created simply by a structure that concentrates stresses at the head portion 112/body portion 114 junction. Alternatively, the housing 102 may be deliberately weakened at or near the head portion 112/body portion 114 junction, or at any other desirably or suitable location. Other anti-tampering solutions apparent to one of skill in the art may be employed as well.

[0037] With continued reference to FIGS. 3 and 4, as described above, the lock cylinder 104 includes a portion referred to as the cartridge 106. The cartridge 106 includes a solenoid 126 with two adjacent slide bars 128. The slide bars 128 are spaced on opposing sides of the solenoid 126 and are configured to magnetically attract to the solenoid 126 when the lock 100 is in the locked position. The slide bars 128 preferably are constructed with a neodymium-containing material, which may be encapsulated in a stainless steel material for corrosion protection and wear resistance. When the lock 100 is moved to an unlocked position, the solenoid 126 is configured to reverse polarity such that the slide bars 128 are magnetically repelled from the solenoid 126, as is described in greater detail below. Preferably, the slide bars 128 are movable along an axis that is parallel to (which includes coaxial with) a longitudinal axis of the lock 100.

[0038] The cartridge 106 is surrounded by a tamper-resistant case 124 that houses a circuit board 134 configured to receive instructions when the key 200 engages with the lock 100. The circuit board 134 is configured to recognize the proper protocol required to unlock the lock 100. The circuit board 134 is further configured to actuate the solenoid 126 to reverse the polarity of the solenoid 126 and repel the slide bars 128 away from the solenoid 126. The details of the circuit board 134 and a preferred method of communication between the key 200 and the lock 100 are discussed in greater detail below. The interior of the case 124 preferably is filled with a filler material, such as an epoxy, to occupy empty space within the case 124 and protect and maintain a desired position of the components within the case 124, such as the circuit board 134 and wires 160.

[0039] The lock cartridge 106 further includes two slide tubes 136 which are positioned on opposite sides of the solenoid 126 and are configured to at least partially encapsulate the slide bars 128 and are further configured to provide a smooth, sliding surface for the slide bars 128. The slide tubes 136 each include an aperture 138 configured to receive at least a portion of a bolt 130, or side bar, of the lock 100 when the lock 100 is in an unlocked position.

[0040] The bolt 130 is preferably a relatively thin, generally block-shaped structure that is movable between a locked position, in which rotation of the lock cylinder 104 relative to the housing 102 is prohibited, and an unlocked position, in which rotation of the lock cylinder 104 relative to the housing 102 is permitted. Preferably, the bolt 130 moves in a radial direction between the locked position and the unlocked position, with the unlocked position being radially inward of the locked position.

[0041] The bolt 130 includes two cylindrical extensions 131, which extend radially inward toward the cartridge 106. When the solenoid 126 is actuated to repel the slide bars 128 such that the apertures 138 are not blocked by the slide bars 128, the extensions 131 of the bolt 130 may enter into the case 124 through the apertures 138 as the bolt 130 moves radially inward.

[0042] The bolt 130 is preferably of sufficient strength to rotationally secure the cylinder 104 relative to the housing 102 when the bolt 130 is in the locked position, wherein a portion of the bolt 130 is present within the groove 120. The bolt 130 has a sloped or chamfered lower edge 129, which in the illustrated embodiment is substantially V-shaped. The lower edge 129 is configured to mate with the groove 120, which preferably is of an at least substantially correspondingly shape to the lower edge 129 of the bolt 130. The V-shaped edge 129 of the bolt 130 interacting with the V-shaped groove 120 of the housing 102 urges the bolt 130 in a radially inward direction towards the cartridge 106 in response to rotation of the cylinder 104 relative to the housing 102. That is, the sloped lower edge 129 and groove 120 cooperate to function as a wedge and eliminate the need for a mechanism to positively retract the bolt 130 from the groove 120. Such an arrangement is preferred at least in part due to its simplicity and reduction in the number of necessary parts. However, other suitable arrangements to lock and unlock the cylinder 104 relative to the housing 102 may also be used.

[0043] When the lock 100 is in an unlocked condition and the slide bars 128 are spaced from the solenoid 126, as shown in FIG. 4, the bolt 130 is free to move radially inward (or upward in the orientation of FIG. 4) into the cartridge 106, thus allowing the cylinder 104 to rotate within the housing 102. Preferably, one or more biasing members, such as springs, tend to urge the bolt 130 toward a locked position. In the illustrated arrangement, two springs 132 are provided to produce such a biasing force on the bolt 130.

[0044] When the lock 100 is in a locked condition, the bolt 130 is extended radially outward into engagement with the groove 120. The bolt 130 is prevented from inward movement out of engagement with the groove 120 due to interference between the extensions 131 and the slide bars 128. When the lock 100 is in the unlocked position, the slide bars 128 are moved away from the solenoid 126 due to a switching of magnetic polarity of the solenoid 126, which is actuated by the circuit board 134. The bolt 130 is then free to move radially inward towards the center of the cylinder 104 and out of engagement with the groove 120. At this point, the rotation of the cylinder 104 within the housing 102 may cause the bolt 130 to be displaced from engagement with the groove 120 due to the cooperating sloped surfaces of the groove 120 and the lower edge 129 of the bolt 130. The cylinder 104 is then free to be rotated throughout the unlocked rotational range within the housing 102. When the cylinder 104 is rotated back to a locked position, that is, when the lower edge 129 of the bolt 130 is aligned with the groove 120, the bolt 130 is urged radially outward by the springs 132 such that the lower edge 129 is engaged with the groove 120. Once the extensions 131 of the bolt 130 are retracted from the case 124 to a sufficient extent, the slide bars 128 are able to move towards the solenoid 126 to once again establish the locked position of the lock 100.

[0045] Although FIG. 3 and FIG. 4 show a housing 102 with only one groove 120, it will be appreciated by one skilled in the art that multiple grooves 120 may be provided within the housing 102. Such a configuration may be advantageous in that multiple bolts 130 may be provided, or if it is desirable to have multiple locked positions using a single bolt 130 interacting with one of several available grooves 120.

[0046] With continued reference to FIGS. 3 and 4, the lock 100 further includes an attack guard portion 110 configured to inhibit access to the cartridge 106 such as by drilling, for example, from the exposed portions of the lock, such as the head portion 112. The illustrated attack guard portion 110 includes a radial array of pins 140 and an attack ball 142, which are located along the longitudinal axis of the lock 100 between the mating portion 108 and the cartridge 106. In the illustrated arrangement, the attack ball 142 is generally centered relative to the longitudinal axis of the lock 100 and is surrounded by the pins 140.

[0047] The pins 140 are preferably made from a carbide material, but can be made of any suitable material or combination of materials that are capable of providing a suitable hardness to reduce the likelihood of successful drilling past the pins 140 and attack ball 142. The pins 140 are inserted into the cylinder 104 to a depth that is near the outer extremity of the attack ball 142. It is preferred that a small space is provided between the outer end of the attack ball 142 and the end of the carbide pin 140 to allow for the passage of the wires 160, which is discussed in greater detail below. The pins 140 are provided so as to add strength and hardness to the outer periphery of the cylinder 104 adjacent to the attack ball 142.

[0048] The attack ball 142 is preferably made of a ceramic material but, similar to the carbide pins, can be made of any suitable material that is of sufficient hardness to reduce the likelihood of successful drilling of the lock cylinder 104. The attack ball 142 is preferably generally spherical shape and lies within a pocket on substantially the same axis as the cartridge 106. Preferably, the attack ball 142 is located in front of the cartridge 106 and is aligned along the longitudinal axis of the lock 100 with the pins 140. The attack ball 142 is configured to reduce the likelihood of a drill bit passing through the cylinder and drilling out the cartridge 106. It is preferable that if an attempt is made to drill out the cylinder 104, the attack ball 142 is sufficiently hard as to not allow the drill bit to drill past the ball 142 and into the cartridge 106. The shape of the attack ball 142 is also advantageous in that it will likely deflect a drill bit from drilling into the cartridge 104 by not allowing the tip of the drill bit to locate centrally relative to the lock 100. Because the attack ball 142 is held within a pocket, it advantageously retains functionality even if cracked or broken. Thus, the attack guard portion 110 is configured to substantially reduce the likelihood of success of an attempt to drill out the cartridge 106. In addition, or in the alternative, other suitable arrangements to prevent drilling, or other destructive tampering, of the lock 100 may be used as well.

[0049] One advantage of using the pins 140 and the attack ball 142 is that the entire lock cylinder 104 does not have to be made of a hard material. Because the lock cylinder 104 includes many features that are formed in the material by shaping (e.g., casting or forging) or material removal (e.g., machining), it would be very difficult to manufacture a cylinder 104 entirely of a hard material such as ceramic or carbide. By using separate pins 140 and an attack ball 142, which are made of a very hard material that is difficult to drill, the lock cylinder 104 can be easily manufactured of a material such as stainless steel which has properties that allow easier manufacture. Thus a lock cylinder can be made that is both relatively easy to manufacture, but also includes drill resistant properties.

[0050] With continued reference to FIGS. 3 and 4, the lock 100 includes a mating portion 108 located near the front portion of the lock 100. The mating portion 108 preferably includes a mechanical mating portion 144 and a data and power mating portion 146. The mechanical mating portion 144 includes a tapered cylindrical extension 148 that extends in a forward direction from the lock cylinder 104 and is configured to be received within a portion of the key 200 when the lock 100 and the key 200 are engaged together. At the base of the extension 148 are two recesses 150 configured to mate with two extensions, or protrusions, on the key 200, which are described in greater detail below. The recesses 150 are configured to allow the key 200 to positively engage the cylinder 104 such that torque can be transferred from the key 200 to the cylinder 104 upon rotation of the key 200.

[0051] The data and power mating portion 146 includes a mating cup 152, a data coil 154, and a power coil 156. The cup 152 is configured to receive a portion of key 200 when the lock 100 and the key 200 are engaged together. The cup 152 resides at least partially in an axial recess 158 which is located in a front portion of the lock cylinder 104 and further houses the attack ball 142. The cup is at least partially surrounded by the power coil 156, which is configured to inductively receive power from the key 200. The cup 152 preferably includes axial slots 161 configured to allow power to transmit through the cup 152.

[0052] The data coil 154 is located towards the upper edge of the cup 152 and, preferably, lies just rearward of the forward lip of the cup 152. The data coil 154 is generally of a torus shape and is configured to cooperate with a data coil of the key 200, as is described in greater detail below. Two wires 160 extend from the cup 152, through a passage 162, and into the lock cartridge 106. The wires 160 preferably transmit data and power from the data and power mating portion 146 to the solenoid 126 and the circuit board 134.

[0053] The power coil 156 is preferably aligned with a longitudinal axis of the lock 100 so that a longitudinal axis passing through the power coil 156 is substantially parallel (or coaxial) with a longitudinal axis of the lock 100. The data coil 154 is preferably arranged to generally lie in a plane that is orthogonal to a longitudinal axis of the lock. Such an arrangement helps to reduce magnetic interference between the transmission of power between the lock 100 and the key 200 and the transmission of data between the lock 100 and the key 200.

[0054] As described above, the lock cylinder 104 is configured to support a lock tab, which interacts with a stop to inhibit opening of a cabinet drawer or door, or prevent relative movement of other structures that are secured by the lock and key system 10. The lock cylinder 104 includes a lock tab portion 164 adapted to support a lock tab in a rotationally fixed manner relative to the lock cylinder 104. The lock tab portion 164 includes a flatted portion 166 and a threaded portion 168. The flatted portion 166 is configured to receive a lock tab (not shown) which can slide over lock tab portion 164 and mate with the flatted portion 166. One or more flat surfaces, or “flats,” on the flatted portion 166 are configured to allow the transmission of torque from the cylinder 104 to the lock tab (not shown). The threaded portion 168 is configured to receive a nut (not shown), which is configured to secure the lock tab (not shown) to the cylinder 104.

[0055] FIGS. 5-7 illustrate a preferred embodiment of the key 200 configured for use with the preferred lock 100 of the electronic lock and key assembly 10. The key 200 is configured to mate with the lock 100 to permit power and data communication between the key 200 and the lock 100. In the illustrated arrangement, the key 200 is further configured to mechanically engage the lock 100 to move the lock from a locked to an unlocked position or vise versa.

[0056] The key 200 includes an elongate main body section 204 that is generally rectangular in cross-sectional shape. The key 200 also includes a nose section 202 of smaller external dimensions than the body section 204. An end section 206 closes and end portion of the body section 204 opposite the nose section 202. The nose section 202 is configured to engage the lock 100 and the body section 204 is configured to house the internal electronics of the key 200 as well as other desirable components. The end section 206 is removable from the body section 204 to permit access to the interior of the body section 204.

[0057] With continued reference to FIGS. 5-7, the nose section 202 includes a tapered transition portion 208 which extends between a cylindrical portion 210 of the nose section 202 and the body section 204. The cylindrical portion 210 houses the power and data transfer portion 212 of the key 200, which is discussed in greater detail below.

[0058] On the outer surface of the cylindrical portion are two radiused tabs 214 which are configured to rotationally locate the key 200 relative to the lock 100 prior to the key 200 engaging the lock 100. The tabs 214 extend radially outward from the outer surface of the cylindrical portion 210 and, preferably, oppose one another.

[0059] The cylindrical portion 210 further includes two generally rectangular extensions 216 that extend axially outward and are configured to engage with the recesses 150 of the lock 100 (FIG. 3) when the key 200 engages the lock 100. The rectangular extensions 216 are configured to couple the nose section 202 of the key 200 to the lock cylinder 104 and to transmit torque from the key 200 to the cylinder 104 when the key 200 is rotated.

[0060] The cylindrical portion 210 comprises a recess 218 that opens to the front of the key 200. Located within the recess 218 is the power and data transfer portion 212 of the key 200. Preferably, the power and data transfer portion 212 is generally centrally located within the recess 218 and aligned with the longitudinal axis of the key 200. The power and data transfer portion 212 includes a power coil 220 and a data coil 222. The power coil 220 is generally cylindrical in shape with a slight taper along its axis. The power coil 220 is positioned forward of the data coil 222 and, preferably, remains within the recess 218 of the cylindrical portion 210. The power coil 220 is configured to be inductively coupled with the power coil 152 of the lock 100. The data coil 222 is generally toroidal in shape and is located at the base of the recess 218. The data coil 222 is configured to be inductively coupled with the data coil 154 of the lock 100, as is described in greater detail below.

[0061] With continued reference to FIGS. 5-7, in the illustrated arrangement, the nose section 202 is a separate component from the body section 204 and is connected to a forward end of the body section 204 of the key 200. The nose section 202 mates with the body section 204 and is sealed by a suitable seal member, such as O-ring 224, which inhibits contaminants from entering the interior of the key 200. The nose section 202 is secured to the body section by two fastening members, such as screws 226 (FIGS. 1 and 5). Similarly, the end section 206 is a separate component from the body section 204 and is coupled to a rearward end of the body section 200. The end section is substantially sealed to the body section 204 by a suitable seal member, such as O-ring 230, which is configured to inhibit contaminants from entering the interior of the key 200. Thus, the key 200 preferably is suitable for use in wet environments. The end section 206 is secured to the body section 204 by a fastening member, such as screw 232, which is configured to retain the end section 206 to the body section 204.

[0062] The body section 204 includes three externally-accessible input buttons 228 extending from the body section 204 (upward in the orientation of FIG. 5). The input buttons 228 are in electrical contact with a processing unit 229 of the key 200, which preferably includes a processor and a memory. The input buttons 228 permit data to be entered into the key 200, such as a wake-up or programming code, for example. Preferred functional features of the key 200 are described in greater detail below with reference to FIGS. 9-12.

[0063] With reference to FIGS. 6 and 7, the key 200 further includes a plurality of axially-extending cavities 236. The illustrated key 200 includes four cavities 236. The axial cavities 236 extend through at least a significant portion of the length of the body section 204 and are preferably circular in cross-sectional shape. The axial cavities 236 are adapted to house battery cells (not shown) that provide a source of power within the key 200, which provides power to the lock 100 when the key 200 and the lock 100 are engaged. The cavities 236 are preferably arranged in a side-by-side manner and surround a longitudinal axis of the key 200. The key 200 preferably includes a power source (discussed below) and is adapted to be rechargeable. Preferably, the key 200 includes a recharge port (not shown), which are configured to mate with an associated recharge port of a recharger (not shown) when it is desired to recharge the key 200.

[0064] With reference to FIGS. 2 and 8, the key 200 is shown about to engage the lock 100, and engaging the lock 100, respectively. When the key 200 engages with the lock 100, desirably, certain mechanical operations occur and certain electrical operations occur. When engaging the key 200 with the lock 100, the key 200 is rotationally positioned relative to the lock 100 such that the tabs 214 of the key 200 are aligned with the slots 176 (FIG. 2) of the lock 100. The key 200 is then displaced axially such that the tabs 214 pass through the slots 176 and the cylindrical portion 210 of the key 200 is positioned within the housing 102 of the lock 100. The key 200 is sized and shaped such that the tabs 214 are located within the annular groove 174, which has a shape that closely matches the profile of the tabs 214. In this relative position, the key 200 is able to rotate within the housing 100, so long as the key 200 is a proper match for the lock 100 and the lock is moved to the unlocked position, as is described in greater detail below.

[0065] Furthermore, when the key 200 engages the lock 100, the cylindrical extension 148 of the lock 100 is received within the recess 218 of the key. The recess 218 is defined by a tapered surface which closely matches a tapered outer surface of the cylindrical extension 148. The cooperating tapered surfaces facilitate smooth engagement of the lock 100 and key 200, while also ensuring proper alignment between the lock 100 and key 200. Furthermore, the rectangular extensions 216 of the key 200 insert into the recesses 150 of the lock 100 to positively engage the key 200 with the lock 100 so that rotation of the key 200 results in rotation of the lock cylinder 104 within the housing 102.

[0066] When the key 200 engages the lock 100, the power coil 220 of the key 200 is aligned for inductive coupling with the power coil 156 of the lock 100. Also, the data coil 222 of the key 200 is aligned for inductive coupling with the data coil 154 of the lock 100. Preferably, the power coil 220 of the key 200 is inserted into the cup portion 152 of the lock 100 and thus the power coil 156 of the lock 100 and the power coil 220 of the key 200 at least partially overlap along the longitudinal axis of the lock 100 and/or key 200. Furthermore, preferably, the data coil 154 of the lock 100 and the data coil 222 of the key 200 come into sufficient alignment for inductive coupling when the key 200 engages the lock 100. That is, in the illustrated arrangement, when the key 200 engages the lock 100, the data coil 222 of the key 200 and the data coil 154 of the lock 100 are positioned adjacent one another and, desirably, are substantially coaxial with one another. Furthermore, a plane which passes through the data coil 222 of the key 200 preferably is substantially parallel to a plane which passes through the data coil 154 of the lock 100. Desirably, the spacing between the data coils 154 and 222 is within a range of about 30-40 mils (or 0.03-0.04 inches). Such an arrangement is beneficial to reduce interference between the power transfer and the data transfer between the lock 100 and key 200, as is described in greater detail below. However, in other arrangements, a greater or lesser amount of spacing may be desirable.

[0067] In the illustrated embodiment of the lock and key system 10, when the key 200 engages the lock 100 there are two transfers that occur. The first transfer is a transfer of data and the second transfer is a transfer of power. During engagement of the key 200 and the lock 100, the data coils 222 and 154, in the illustrated embodiments, do not come into physical contact with one another. Similarly, the power coil 200 of the key 200 and power coil 156 of the lock 100, in the illustrated embodiment, do not come into physical contact with one another. The data is preferably transferred between the data coil 222 of the key 200 and the data coil 154 of the lock 100 by induction, as described in connection with FIG. 9 below. The power is also transferred between the power coil 200 of the key 200 and the power coil 156 of the lock 100 preferably once again by induction, as is also described in connection with FIG. 9 below. When engagement between the key 200 and the lock 100 has been made, a data protocol occurs which signals to the circuit board 134 that the proper key 200 has been inserted into the lock 100. Power is transferred from the key 200 to the lock 100 to activate the solenoid 126, which permits the lock 100 to be unlocked by rotation of the key 200.

Electrical Aspects of the Key and Lock System

[0068] FIG. 9 depicts a magnetic field diagram 400 in accordance with certain embodiments of the present invention. In the magnetic field diagram 400, a cross-section view of a power coil 402, interior power coil 418, first data coil 406, and second data coil 408 are depicted in relation to a power magnetic field 404 and a data magnetic field 410 generated by the coils 406 and 408. In the depicted embodiment, the configuration of the power coil 402, interior power coil 418, first data coil 406, and second data coil 408 causes the power magnetic field 404 to be orthogonal or substantially orthogonal to the data magnetic field 410 at certain locations. This orthogonal relationship facilitates data transfer between the data coils 406, 408 with little or no interference from the power magnetic field 404. The coils 402, 406, 408 and 418, as illustrated, correspond with the power and data coils of the lock 100 and key 200 of FIGS. 1-8. In particular, the power coil 402 corresponds with the lock power coil 156, the interior power coil 418 corresponds with the key power coil 220, the data coil 406 corresponds with the lock data coil 154 and the data coil 408 corresponds with the key data coil 222. However, it will be apparent to one of skill in the art that the physical relationships between the coils may be altered in alternative embodiments from the locations shown in FIGS. 1-8; however, preferably the interference reduction or elimination concepts disclosed herein are still employed.

[0069] The power coil 402 of certain embodiments is a solenoid. The solenoid includes windings 420 which are loops of wire that are wound tightly into a cylindrical shape. In the depicted embodiment, the power coil 402 includes two sets of windings 420. Two sets of windings 420 in the power coil 402 reduce air gaps between the wires and thereby increase the strength of a magnetic field generated by the power coil 402.

[0070] The depicted embodiment of the power coil 402 does not include a magnetic core material, such as an iron core, although in certain embodiments, a magnetic core material may be included in the power coil 402. In addition, while the power coil 402 is depicted as a solenoid, other forms of coils other than solenoids may be used, as will be understood by one of skill in the art.

[0071] The power coil 402 may form a portion of a lock assembly, though not shown, such as any of the lock assemblies described above. Alternatively, the power coil 402 may be connected to a key assembly, such as any of the key assemblies described above. In addition, the power coil 402 may be connected to a docking station (not shown), as described in connection with FIG. 10, below.

[0072] The power coil 402 is shown having a width 414 (also denoted as “W_P”). The width 414 of the power coil 402 is slightly flared for the entire length of the power coil 402. The overall shape of the power coil 402, including its width 414, determines in part the shape of the magnetic field emanating from the power coil 402. In certain embodiments, a constant or approximately constant width 414 of the power coil 402 does not change the shape of the power magnetic field 404 substantially from the shape illustrated in FIG. 9.

[0073] The power coil 402 further includes a casing 462 surrounding the power coil 402. In one embodiment, the casing 462 is a non-conducting material (dielectric). The casing 462 of certain embodiments facilitates the power coil 402 receiving the interior power coil 418 inside the power coil 402. The casing 462 prevents electrical contact between the power coil 402 and the interior power coil 418. Thus, in the embodiment described with reference to FIGS. 1-8, the cup 152 of the lock 100 may be constructed from, or include, an insulation material. Furthermore, other physical structures interposed between adjacent coils may be made from, or include, insulating materials.

[0074] In alternative embodiments, the casing 462 is made of a metal, such as steel. The strength of a metal casing 462 such as steel helps prevent tampering with the power coil 402. However, magnetic fields typically cannot penetrate more than a few layers of steel and other metals. Therefore, the metal casing 462 of certain embodiments includes one or more slits or other openings (not shown) to allow magnetic fields to pass between the power coil 402 and the interior power coil 418.

[0075] The interior power coil 418 mates with the power coil 402 by fitting inside the power coil 402. In certain embodiments, the interior power coil 418 has similar characteristics to the power coil 402. For instance, the interior power coil 418 in the depicted embodiment is a solenoid with two windings 420. In addition, the interior power coil 418 may receive a current and thereby generate a magnetic field. The interior power coil 418 is also covered in a casing material 454, which may be an insulator or metal conductor, to facilitate mating with the power coil 402. Furthermore, the interior power coil 418 also has a width 430 (also denoted “W_i”) that is less than the width 414 of the power coil 402, thereby allowing the interior power coil 418 to mate with the power coil 402.

[0076] In addition to these features, the interior power coil 418 of certain embodiments includes a ferromagnetic core 452, which may be a steel, iron, or other metallic core. The ferromagnetic core 452 increases the strength of the power magnetic field 404, enabling a more efficient power transfer between the interior power coil 418 and the power coil 402. In addition, the ferromagnetic core 452 in certain embodiments enables the frequency of the power signal to be reduced, allowing a processor in communication with the power coil 418 to operate at a lower frequency and thereby decrease the cost of the processor.

[0077] The interior power coil 418 may form a portion of a lock assembly, though not shown, such as any of the lock assemblies described above. Alternatively, the interior power coil 418 may be connected to a key assembly, such as any of the key assemblies described above. In addition, the interior power coil 418 may be connected to a docking station (not shown), as described in connection with FIG. 10, below.

[0078] A changing current flow through the interior power coil 418 induces a changing magnetic field. This magnetic field, by changing with respect to time, induces a changing current flow through the power coil 402. The changing current flow through the power coil 402 further induces a magnetic field. These two magnetic fields combine to form the power magnetic field 404. In such a state, the power coil 402 and the interior power coil 418 are “inductively coupled,” which means that a transfer of energy from one coil to the other occurs through a shared magnetic field, e.g., the power magnetic field 402. Inductive coupling may also occur by sending a changing current flow through the power coil 402, which induces a magnetic field that in turn induces current flow through the interior power coil 418. Consequently, inductive coupling may be initiated by either power coil.

[0079] Inductive coupling allows the interior power coil 418 to transfer power to the power coil 402 (and vice versa). An alternating current (AC) signal flowing through the interior power coil 418 is communicated to the power coil 402 through the power magnetic field 404. The power magnetic field 404 generates an identical or substantially identical AC signal in the power coil 402. Consequently, power is transferred between the interior power coil 418 and the power coil 402, even though the coils are not in electrical contact with one another.

[0080] In certain embodiments, the interior power coil 418 has fewer windings than the power coil 402. A voltage signal in the interior power coil 418 is therefore amplified in the power coil 402, according to known physical relationships in the art. Likewise, a voltage signal in the power coil 402 is reduced or attenuated in the interior power coil 418. In addition, the power coil 402 may have fewer windings than the interior power coil 418, such that a voltage signal from the interior power coil 418 to the power coil 402 is attenuated, and a voltage signal from the power coil 402 to the interior power coil 418 is amplified.

[0081] The power magnetic field 404 is shown in the depicted embodiment as field lines 434; however, those of skill in the art will understand that the depiction of the power magnetic field 404 with field lines 434 is only a model or representation of actual magnetic fields, which in some embodiments are changing with respect to time. Therefore, the power magnetic field 404 in certain embodiments is depicted at a moment in time. Moreover, the depicted model of the power magnetic field 404 includes a small number of field lines 434 for clarity, but in general the power magnetic field 404 fills all or substantially all of the space depicted in FIG. 9.

[0082] Portions of the field lines 434 of the power magnetic field 404 on the outside of the power coil 402 are parallel or substantially parallel to the axis of the power coil 402. The parallel nature of these field lines 434 in certain embodiments facilitates minimizing interference between power and data transfer, as is described below.

[0083] The first data coil 406 is connected to the power coil 402 by the casing 462. The first data coil 406 has one or more windings 422. In one embodiment, the first data coil 406 is a toroid comprising tightly-wound windings 422 around a ferromagnetic core 472, such as steel or iron. The ferromagnetic core 472 of certain embodiments increases the strength of a magnetic field generated by the first data coil 406, thereby allowing more efficient transfer of data through the data magnetic field 410. In addition, the ferromagnetic core 472 in certain embodiments enables the frequency of the data signal to be reduced, allowing a processor in communication with the first data coil 406 to operate at a lower frequency and thereby decreasing the cost of the processor.

[0084] Though not shown, the first data coil 406 may further include an insulation material surrounding the first data coil 406. Such insulation material may be a non-conducting material (dielectric). In addition, the casing 462 covering the power coil 402 in certain embodiments also at least partially covers the first data coil 406, as shown. The casing 462 at the boundary between the first data coil 406 and the second data coil 408 may also include a slit or other opening to allow magnetic fields to pass between the first and second data coils 406, 408.

[0085] The first data coil 406 has a width 416 (also denoted as “W_d”). This width 416 is greater than the width 414 of the power coil 402 in some implementations. In alternative embodiments, the width 416 may be equal to or less than the width 414 of the power coil 402.

[0086] The second data coil 408 in the depicted embodiment is substantially identical to the first data coil 406. In particular, the second data coil 408 is a toroid comprising tightly-wound windings 424 around a ferromagnetic core 474, such as steel or iron. The ferromagnetic core 474 of certain embodiments increases the strength of a magnetic field generated by the second data coil 408, thereby allowing more efficient transfer of data through the data magnetic field 410, allowing a processor in communication with the second data coil 408 to operate at a lower frequency and thereby decreasing the cost of the processor.

[0087] The second data coil 408 in the depicted embodiment has a width 416 equal to the width 414 of the first data coil 406. In addition, the second data coil 408 may have an insulating layer (not shown) and may be covered by the casing 454, as shown. However, in certain embodiments, the second data coil 408 has different characteristics from the first data coil 406, such as a different number of windings 424 or a different width 416. In addition, first and second data coils 406, 408 having different widths may overlap in various ways.

[0088] When a current is transmitted through either the first data coil 406 or the second data coil 408, the first data coil 406 and the second data coil 408 are inductively coupled, in a similar manner to the inductive coupling of the power coil 402 and the interior power coil 418. Data in the form of voltage or current signals may therefore be communicated between the first data coil 406 and the second data coil 408. In certain embodiments, data may be communicated in both directions. That is, either the first or second data coil 406, 408 may initiate communications. In addition, during one communication session, the first and second data coils 406, 408 may alternate transmitting data and receiving data.

[0089] Data magnetic field 410 is depicted as including field lines 442, a portion of which are orthogonal or substantially orthogonal to the data coils 406, 408 along their width 416. Like the field lines 434, 436 of the power magnetic field 404, the field lines 442 of the data magnetic field 410 are a model of actual magnetic fields that may be changing in time. The orthogonal nature of these field lines 442 in certain embodiments facilitates minimizing the interference between power and data transfer.

[0090] In various embodiments, at least a portion of the data magnetic field 410 is orthogonal to or substantially orthogonal to the power magnetic field 404 at certain areas of orthogonality. These areas of orthogonality include portions of an interface 412 between the first data coil 406 and the second data coil 408. This interface 412 in certain embodiments is an annular or circumferential region between the first data coil 406 and second data coil 408. At this interface, at least a portion of the data magnetic field 410 is substantially parallel to the first data coil 406 and second data coil 408. Because the data magnetic field 410 is substantially parallel to the data coils 406, 408, the data magnetic field 410 is therefore substantially orthogonal to the power magnetic field 404 at portions of the interface 412.

[0091] According to known relationships in the physics of magnetic fields, magnetic fields which are orthogonal to each other have very little effect on each other. Thus, the power magnetic field 404 at the interface 412 has very little effect on the data magnetic field 410. Consequently, the data coils 406 and 408 can communicate with each other with minimal interference from the potentially strong power magnetic field 404. In addition, data transmitted between the data coils 406, 408 does not interfere or minimally interferes with the power magnetic field 404. Thus, data may be sent across the data coils 406, 408 simultaneously while power is being sent between the power coil 402 and the interior power coil 418.

[0092] FIG. 10 depicts a key circuit 510 and a lock circuit 530 in accordance with certain embodiments of the present invention. In the depicted embodiment, the key circuit 510 is shown in proximity to the lock circuit 530. The relative locations of the key circuit 510 and the lock circuit 530 shows that in certain implementations components of the key circuit 510 interface with components of the lock circuit 530. Moreover, the key circuit 510 may in certain embodiments be contained in a key assembly such as any of the keys described above. Likewise, the lock circuit 530 may be contained in a lock assembly such as any of the locks described above.

[0093] The key circuit 510 includes a processor 502. The processor 502 may be a microprocessor, a central processing unit (CPU), a microcontroller, or other type of processor. The processor 502 in certain embodiments implements program code. By implementing program code, the processor 502 sends certain signals to the lock circuit 530 and receives signals from the lock circuit 530. Such signals may include power signals, data signals, and the like.

[0094] A memory device 526 is in communication with the processor 502. The memory device 526 in certain embodiments is a flash memory, hard disk storage, an EEPROM, or other form of storage. The memory device 526 in certain embodiments stores program code to be run on the processor 502. In addition, the memory device 526 may store data received from the processor 502.

[0095] Data stored on the memory device 526 may include encryption data. In one embodiment, the encryption data includes one or more encryption keys that when communicated to the lock circuit 530 effectuate unlocking a lock. Several different encryption schemes may be used, as will be appreciated by one having skill in the art.

[0096] Data stored by the memory device 526 may also include audit data. Audit data in some implementations is data received from the lock circuit 530 or generated by the key circuit 510 that identifies past transactions that have occurred between the lock and other keys. For instance, audit data may include ID numbers of keys used to access the lock, including keys which unsuccessfully used the lock. This data allows security personnel to monitor which individuals have attempted to access the lock. The audit data may further include several other types of information as will be understood by one of skill in the art.

[0097] A data coil 512 is in communication with the processor 502 through conductors 504 and 506. The data coil 512 may be any of the data coils described above. The data coil 512 in certain embodiments receives data from the processor 502. This data may be in the form of a voltage or current signal which changes with respect to time, such that certain changes in the signal represent different symbols or encoded information. Because the signal changes with respect to time, a magnetic field is generated in the data coil 512 which induces a magnetic field in a corresponding data coil 532 in the lock circuit 530. The magnetic field in the data coil 532 further induces a voltage or current signal, which contains the same information or substantially the same information as the voltage or current signal generated in the data coil 512. Thus, the data coil 512 facilitates communication between the key circuit 510 and the lock circuit 530.

[0098] In certain embodiments, the data coil 512 receives data in a like manner from the data coil 532 of the lock circuit 530. A voltage or current signal induced in the data coil 512 is sent to the processor 502, which processes the information conveyed in the voltage or current signal. The data coil 512 may also send and receive information to and from a docking station (not shown), which is described more fully below.

[0099] One or more switches 516 are in communication with the data coil 512 and with the processor 502. The switches 516 in certain embodiments are transistor switches, relays, or other forms of electronic switches which selectively direct current flow to different parts of the key circuit 510. In the depicted embodiment, switches 516 direct current flow between the data coil 512 and the processor 502. The switches 516 therefore selectively allow the processor 502 to both send and receive data.

[0100] A power coil 514 is in communication with the processor 502 via conductors 508 and 510. The power coil 514 in certain embodiments transmits power to the key circuit 530. In certain implementations, the power coil 514 may be any of the power coils described above. In one implementation, the power coil 514 receives an alternating current (AC) signal. This AC signal induces a magnetic field in a corresponding power coil 534 in the lock circuit 530. In one embodiment, the AC signal oscillates at an appropriate frequency to effectuate optimal power transfer between the key circuit 510 and the lock circuit 530. For example, the oscillation may occur at 200 kilohertz. Alternatively, the oscillation may occur at a different frequency which may be chosen so as to minimize interference with other circuit components.

[0101] One or more switches 518 are in communication with the power coil 514 and a processor 502. Like the switches 516, the switches 518 may be transistor switches, relays or any other form of electronic switch. The switches 518 in certain embodiments allow power to be transmitted to the power coil 514 from the processor 502. In such embodiments, the switches 518 are closed, allowing current to transfer from the processor 502 to the power coil 514. The switches 518 may be opened when the power coil 514 is receiving power such as from a docking station. When the switches 518 are open, power received from the power coil 514 in certain embodiments cannot be transmitted to the processor 502. The switches 518 therefore protect the processor 502 from receiving harmful current signals while simultaneously allowing the processor 502 to transmit power to the power coil 514.

[0102] A rectifier circuit 520 is in communication with the power coil 514 via conductors 508 and 510. The rectifier circuit 520 in certain embodiments includes one or more diodes. The diodes may form a bridge rectifier or other form of rectifier as will be appreciated by those of skill in the art. The diodes of the rectifier circuit 520 rectify an incoming signal from the power coil 514. Rectification in certain embodiments includes transforming an alternating current signal into a direct current signal by converting the AC signal into one of constant polarity. Rectification may further include smoothing the signal, for example, by using one or more capacitors, and thereby creating a direct current signal that can power circuit components.

[0103] A recharge circuit 522 is in communication with the rectifier 520. The recharge circuit 522 in certain embodiments recharges a battery 524 when the key circuit 510 is in communication with a docking station (not shown). The battery 524 may be a lithium iron battery, a nickel cadmium battery or other form of rechargeable battery. The battery may also be an alkaline or other non-rechargeable battery. In addition, the battery 524 may include multiple batteries. In one embodiment, the battery 524 receives power from the recharge circuit 522 in order to recharge the battery. In addition, the battery 524 sends power to the processor 502, to the memory device 526, and to other components in the key circuit 530.

[0104] In some implementations, the key circuit 510 is capable of communicating with a docking station (not shown) connected to an AC power supply, such as a wall outlet. The docking station in one embodiment has a power coil and a data coil, similar to a power coil 534 and data coil 532 of the lock circuit 530 described below. The docking station receives the data coil 512 and the power coil 514 such that the key circuit 510 can communicate with the docking station. In one embodiment, the power coil 514 receives power from the docking station and transfers this power to the rectifier 520 and recharge circuit 522, effectuating recharge of the battery 524.

[0105] In addition, the data coil 512 may receive data from a corresponding data coil in the docking station. Such information might include, for example, program code to be stored on the memory device 526, program code to be run on the processor 502, data to be stored in the memory device 526 including encryption data, data regarding locking codes and the like, as well as ID data, tracking data, and the like. In addition, the docking station may transmit data, codes, or the like to the key circuit 510 which enable the key to be used for a limited time, such as a couple of hours or days. The data coil 512 may also transmit data to the docking station via a corresponding data coil. Such data might also include audit information, tracking information, and the like.

[0106] The docking station may also be connected to a computer. Programs can be run on the computer which facilitate the docking station communicating with the key circuit 510. Consequently, the key circuit 510 may be recharged and reprogrammed by the docking station of certain embodiments.

[0107] Turning to the lock circuit 530, the lock circuit 530 includes a processor 546. Like the processor 502 of the key circuit 510, the processor 546 may be a microprocessor, a central processing unit (CPU), or any other type of processor. The processor 546 in certain embodiments implements program code. By implementing program code, the processor 546 may send certain signals to the key circuit 510 and receive signals from the key circuit 510. Such signals may include power signals, data signals, and the like.

[0108] A memory device 548 is in communication with the processor 546. The memory device 548 in certain embodiments is a flash memory, hard disk storage, an EEPROM, or other form of storage. The memory device 548 in certain embodiments stores program code to be run on the processor 546. In addition, the memory device 548 may store data received from the processor 546.

[0109] Data stored on the memory device 548 may include encryption data. In one embodiment, the encryption data includes one or more encryption keys. When an identical encryption key is received from a key circuit 510 in certain embodiments, the lock circuit 530 unlocks a lock. The memory device 548 may also include audit data. This data allows security personnel to monitor which individuals have attempted to access the lock.

[0110] A data coil 532 is in communication with the processor 546 through conductors 536 and 538. The data coil 532 may be any of the data coils described above. The data coil 532 in certain embodiments receives data from the processor 546 and transmits the data to the key circuit 510. In other embodiments, the data coil 532 receives data from the key circuit 510 via magnetic fields generated by the data coil 512.

[0111] One or more switches 544 are in communication with the data coil 532 and with the processor 546. The switches 544 in certain embodiments are transistor switches, relays, or other forms of electronic switches which selectively direct current flow to different parts of the key circuit 530. In the depicted embodiment, switches 544 may be used to direct current flow between the data coil 532 and the processor 546. Like the switches 516 in the key circuit 510, the switches 544 selectively allow the processor 502 to both send and receive data.

[0112] A power converter 550 is in communication with the processor 546 and with the power coil 534. The power converter 550 in one embodiment includes a rectifier circuit such as the rectifier circuit 528 described above. The power converter 550 may further include a low drop-out regulator (described in connection with FIG. 11, below). In addition, the power converter may include other circuit components common to power regulation as will be understood by one of skill in the art.

[0113] In one embodiment, the power converter 550 receives an oscillating power signal from the power coil 534. The power converter 550 includes a rectifier circuit, similar to the rectifier circuit 520 described above, which converts the oscillating signal into two components, namely an AC component signal and a direct current (DC) component signal. In one embodiment, the AC component signal is provided to a solenoid 552 through conductor 574, and the DC component signal is provided to the processor 546 through conductor 572. Consequently, the power converter 550 enables the lock circuit 530 to run on both AC and DC power.

[0114] The solenoid 552 receives the AC component signal from the power converter 550. The solenoid 552 in one embodiment is a coil containing one or more windings. The solenoid 552, upon receiving current from the power converter 550, generates a magnetic field to actuate an unlocking mechanism in a lock, in a manner similar to that which is described above.

[0115] A switch 554 is in communication with the solenoid 552 through a conductor 576. The switch 554 is also in communication with the processor 546 through a conductor 580. In addition, the switch 554 is in communication with ground 578. The switch 554 enables or disables the solenoid 552 from receiving current, thereby causing the solenoid 552 to lock or unlock. In one embodiment, the processor 546 sends a signal through the conductor 580 to the switch 554 that closes the switch 554 and thereby creates a conduction path from the solenoid 552 to ground 578. With the switch closed 554, the solenoid 552 is able to receive current from the power converter 550 and thereby effectuate unlocking. At other times, the processor 546 will not send a signal 580 to the switch 554 and thereby cause the switch to be open, preventing current from flowing through the solenoid 552 and thereby locking the lock. Alternatively, the processor 546 can send a signal over the signal line 580 to the switch 554 which will cause the switch to remain open.

[0116] While not shown, in certain embodiments the lock circuit 530 includes a battery in addition to, or in place of, the battery 524 in the key circuit 500. In such instances, the lock circuit 530 may provide power to the key circuit 510. This power may recharge the battery 524. Alternatively, if the key circuit 510 does not have a battery 524, power transmitted from the battery in the lock circuit 530 may power the key circuit 510.

[0117] FIGS. 11A and 11B depict one specific implementation of a key circuit, referred to by the reference numeral 600, which is substantially similar in structure and function to the key circuit 510 described above. FIGS. 11A and 11B depict separate portions of the key circuit 600, but these separate portions together constitute one key circuit 600. Certain components of the key circuit 600 are therefore duplicated on each FIG. to more clearly show the relationship between the portion of the key circuit 600 depicted in FIG. 11A with the portion of the key circuit 600 depicted in FIG. 11B. Although the implementation shown in FIGS. 11A and 11B is preferred, other suitable implementations may also be used, which may include features alternative or additional to those described above.

[0118] A processor 602 in the key circuit 600 is in communication with a memory device 626, similar to the processor 502 and the memory device 526 of the key circuit 510. In the depicted embodiment, the processor 602 is a microcontroller and the memory device 626 is a flash memory device. While the processor 602 and the memory device 626 are shown on both FIGs. 11A and 11B, in the depicted embodiment only one processor 602 and one memory device 626 are employed in the key circuit 600. However, in other embodiments, multiple processors 602 and memory devices 626 may be used, as will be appreciated by one of skill in the art.

[0119] A data coil 612, shown in FIG. 11B, is in communication with the processor 602 through conductors 604 and 606. The data coil 612 in the depicted embodiment is a coil or solenoid which has a value of inductance (a measure of changing magnetic energy for a given value of current). In one embodiment, the inductance of the data coil 612 is 100 μH (micro-Henries). In certain embodiments, the data coil 612 sends data to and receives data from a lock circuit 700 (shown in FIG. 12).

[0120] Transistors 616 are depicted as switches in FIG. 11B. Similar to the switches 516, the transistors 616 selectively direct current flow between the data coil 612 and the processor 602. Control signals sent on conductors 662 from the processor 602 selectively allow current to flow through the transistors 616. When the transistors 616 are activated by control signals from the processor 602, and when the processor 602 is sending signals to the data coil 612, the data coil 612 transmits the data. Alternatively, when the data coil 612 is receiving data, the transistors 616 in conjunction with other circuit components direct the data to the processor 602 through the ACDATA line 664. Consequently, the key circuit 600 can both send and receive data on the data coil 612.

[0121] Various encoding schemes may be used to transmit and receive data. For example, a Manchester encoding scheme may be used, where each bit of data is represented by at least one voltage transition. Alternatively, a pulse-width modulation scheme may be employed, where a signal's duty cycle is modified to represent bits of data. Using different encoding schemes may allow the key circuit 600 to contain fewer components. For example, when a pulse-width modulation scheme is used, such as in FIGS. 13A and 13B below, fewer transistors 616 may be employed. By employing fewer components, the key circuit 600 of certain embodiments may be reduced in size, allowing a corresponding key assembly to be reduced in size. In addition, using a relatively simple modulation scheme such as Manchester encoding or pulse-width modulation reduces the need for filters (e.g., low-pass filters), thereby further reducing the number of components in the key circuit 600.

[0122] A power coil 614 is in communication with the processor 604 through conductors 608 and 610 (see FIG. 11B). In one embodiment, the inductance of the power coil 612 is 10 μH (micro-Henries). Like the power coil 514 of FIG. 10, the power coil 614 in certain embodiments transmits power to the lock circuit 700 described in connection with FIG. 12, below.

[0123] In the depicted embodiment, the processor 602 generates two oscillating signals which are provided to the power coil 614. In the depicted embodiment, the oscillating power signals oscillate at 200 kHz (kilohertz). The relative high frequency of the power signal in certain embodiments facilitates improved rectification of the power signal and therefore a more efficient power transfer. In alternative embodiments other frequencies may be chosen without departing from the scope of the present invention.

[0124] In one embodiment, the power signals sent over power coil 614 oscillate at a higher frequency than the data signals sent over the data coil 612. When the power signals oscillate at a higher frequency than the data signals, interference between power and data signals is further minimized, e.g., the signal-to-noise ratio (SNR) is improved. In one embodiment, significant SNR improvements occur when the power signal frequency is greater than 10 times the data signal frequency.

[0125] Diodes 620 are in communication with the power coil 614 through conductors 608 and 610. The diodes 620 in the depicted embodiment form a rectifier circuit, similar to the rectifier circuit 520 of FIG. 10. The depicted configuration of the diodes 620 constitutes a bridge rectifier, or full wave rectifier. The bridge rectifier receives power from the power coil 614 when, for example, the key circuit 600 is in communication with a docking station. In such instances, the diodes 620 of the bridge rectifier in conjunction with a capacitor 684 convert an incoming AC signal into a DC signal. This DC signal is denoted by voltage Vpp 682 in the depicted embodiment.

[0126] The voltage Vpp 682 is provided to a recharge circuit 622 (see FIG. 11A). The recharge circuit 622 recharges a battery 624 using Vpp 682. The battery 624 outputs a voltage Vcc 696, which is sent to various components of the key circuit 600 including to a voltage regulator 690. The voltage regulator 690 provides a constant voltage to a supervisory circuit 692, which is in communication with a backup battery 694. If the battery 624 fails, in certain embodiments, the supervisory circuit 692 provides power to the circuit through the backup battery 694. Consequently, data stored in the memory device 626 is protected from loss by the supervisory circuit 692 and by the backup battery 694.

[0127] FIG. 12 depicts a specific implementation of a lock circuit, generally referred to by the reference numeral 700, which is substantially similar in structure and function to the lock circuit 530 described above. The lock circuit 700 includes a processor 746. The processor 746, like the processor 602, is a microcontroller. The processor 746 communicates with a memory device 748, which in the depicted embodiment is a flash memory. Although the specific implementation of the lock circuit 700 illustrated in FIG. 12 is a preferred implementation of the lock circuit 530, other suitable implementations may also be used, which may include alternative or additional features to those described above.

[0128] In the lock circuit 700, a data coil 732 is in communication with the processor 746 through conductors 736 and 738. The data coil 732 in the depicted embodiment is a coil or solenoid which has a value of inductance. In one embodiment, the inductance of the data coil 732 is 100 μH (micro-Henries). The data coil 732 receives data from and sends data to the data coil 612 of the key circuit 600.

[0129] In one embodiment, data provided by the key circuit 600 and received by the data coil 732 provides a clock signal to the processor 746, enabling the processor 746 to be synchronized or substantially synchronized with the processor 602 of the key circuit 600. The clock signal may be provided, for example, when a Manchester encoding scheme is used to transmit the data. In certain embodiments, this external clock signal removes the need for a crystal oscillator in the lock circuit 700, thereby reducing the number of components and therefore the size of the lock circuit 700.

[0130] Transistors 744 are depicted as switches. Similar to the switches 544, the transistors 744 selectively direct current flow between the data coil 732 and the processor 746. Control signals sent on conductor 782 from the processor 746 control the transistors 744, selectively allowing current to flow through the transistors 744.

[0131] A power coil 734 is in communication with the processor 746 through conductors 740 and 742. In one embodiment, the inductance of the power coil 734 is 10 μH (micro-Henries). Like the power coil 532 of FIG. 10, the power coil 734 in certain embodiments receives power from the key circuit 600. In the depicted embodiment, the power coil 734 provides an AC voltage signal to power conversion circuit 750.

[0132] Power conversion circuit 750 includes diodes 720, a capacitor 790, and a low-dropout regulator 760. The diodes 720 of the power conversion circuit 750 form a rectifier circuit. The depicted configuration of the diodes 720 constitutes a bridge rectifier, or full wave rectifier. When the diodes 720 receive an AC voltage signal from the power coil 734, the diodes 720 of the bridge rectifier full-wave rectify the AC voltage signal. This full-wave rectified signal in certain embodiments still contains a changing voltage signal with respect to time, but the voltage signal has a single polarity (e.g., the entire voltage signal is positive). This full-wave rectified signal is provided as voltage Vcc 784 to a solenoid 752.

[0133] The capacitor 790 converts the full-wave rectified signal into DC form and provides the DC signal to the low-dropout regulator 760. The low-dropout regulator 760 stabilizes the signal to a voltage Vdd 772, which is provided to various components in the lock circuit 700, including the processor 746. Consequently, the power conversion circuit 750 provides a changing or AC voltage Vcc 784 to the solenoid 752 and a DC voltage Vdd 772 to various circuit components.

[0134] The solenoid 752 receives the voltage Vcc 784 from the power converter 750. The solenoid 752 in one embodiment is a coil containing one or more windings. The solenoid 752, upon receiving the voltage Vcc 784 from the power converter 550, generates a magnetic field to actuate an unlocking mechanism in a lock, in a manner similar to that which is described above.

[0135] A transistor 754 is in communication with the solenoid 752. The transistor 754 is also in communication with the processor 746 through a conductor 780. In addition, the transistor 754 is in communication with ground 778. In certain embodiments, the transistor 754 acts as a switch to enable or disable the solenoid 752 from receiving current, thereby causing the solenoid 752 to lock or unlock the locking device. In one embodiment, the processor 746 sends a signal through the conductor 780 to the transistor 754 that sends current through the transistor 754 and thereby creates a conduction path from the solenoid 752 to ground 778. With the transistor 754 in this state, the solenoid 752 is able to receive current from the voltage Vcc 784 and thereby effectuate unlocking. However, at other times, the processor 746 will not send a signal 780 to the transistor 754, such as when the processor 746 did not receive a correct unlocking code. In such case, the processor 746 causes the transistor 754 to remain open, thereby preventing current from flowing through the solenoid.

[0136] FIGS. 13A and 13B depict another specific implementation of a key circuit, referred to by the reference numeral 800, which is substantially similar in structure and function to the key circuit 600 described in FIGS. 11A and 11B above. In certain embodiments, certain elements of the key circuit 600, such as circuit components 860, 872, and 874 (shown in FIG. 13B), may also be employed in a corresponding lock circuit (not shown).

[0137] In the depicted embodiment, circuit components 860, 872, and 874 in conjunction with a processor provide circuitry for a pulse-modulation data-encoding scheme. During transmission of data from the key circuit 800, transistor switches 860 are selectively switched on and off to pulse a data signal to a data coil. When the key circuit 800 is receiving data, the comparator 872 receives the data voltage signal from the data coil.

[0138] The comparator 872 is used to convert the data voltage signal into a two-bit digital signal which is sent to a processor via data input line 880. In addition, the comparator 872 (or an operational amplifier used as a comparator) may be used to amplify the voltage signal to a level appropriate for a processor to manipulate.

[0139] A feedback resistor 874 provides positive feedback to the comparator 872, such that the comparator 872 attenuates small voltage signals and amplifies large voltage signals. By attenuating and amplifying small and large voltage signals respectively, the comparator 872 and feedback resistor 874 reduce the oscillatory effects of noise on the comparator 872. Thus, wrong-bit detection errors are reduced. In alternative embodiments, a Schmitt trigger integrated circuit may be employed in place of the comparator 872 and the resistor 874.

[0140] While various embodiments of key and lock circuits have been depicted, those of skill will further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

[0141] The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein can be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor can be a microprocessor, conventional processor, controller, microcontroller, state machine, etc. A processor can also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In addition, the term “processing” is a broad term meant to encompass several meanings including, for example, implementing program code, executing instructions, manipulating signals, filtering, performing arithmetic operations, and the like.

[0142] In addition, although this invention has been disclosed in the context of a certain preferred embodiment, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiment to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In particular, while the present key and lock system has been described in the context of a particularly preferred embodiment, the skilled artisan will appreciate, in view of the present disclosure, that certain advantages, features and aspects of the key and lock system may be realized in a variety of other applications. Additionally, it is contemplated that various aspects and features of the invention described can be practiced separately, combined together, or substituted for one another, and that a variety of combination and subcombinations of the features and aspects can be made and still fall within the scope of the invention. Furthermore, the systems described above need not include all of the modules and functions described in the preferred embodiments. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiment described above, but should be determined only by a fair reading of the claims that follow.