Method for unlocking a wireless lock with a wireless key

Abstract

Method for unlocking a radio lock (10) with a radio key (20), wherein the radio lock (10) and the radio key (20) communicate with each other without user intervention, characterized in that - with a capacitive sensor, which forms at least part of the radio key (20), detects whether the radio key (20) is being held by the user, - the radio lock (10) will only be released if the radio key (20) is held and the radio key (20) is authorized to release the radio lock (10).

Description

Technical field

[0001] The invention relates to a method for releasing a radio lock with a preferably active radio key and a radio key for carrying out the method. State of the art

[0002] Electromechanical locking systems typically consist of at least one wireless key and at least one wireless lock, which protects, for example, a front door, an office door, a cabinet door, or similar doors against unauthorized opening. Wireless keys communicate via a contactless data link with the nearest wireless lock (DE 10 2007 058 367), checking, among other things, whether the wireless key is authorized to open the lock (DE 19913931 B4 with further references). If authorization is granted, the door is unlocked. In some cases, a handle, such as a doorknob, is then coupled with a locking mechanism, such as a latch or bolt (DE 10 2008 001 693); in other cases, the handle is unlocked, or the door opens automatically. This is also referred to as unlocking the wireless lock.

[0003] A distinction is made between so-called passive and active key fobs, which are usually referred to simply as passive or active keys. Passive key fobs generally do not have their own power supply, but draw the energy to power their electrical components from an alternating electromagnetic field, usually emitted by the key fob. The typical maximum distance between the key fob and a passive key fob, at which communication between the two is possible, is approximately 0.1 meters (in exceptional cases up to 0.5 meters). To transmit data from the passive key fob to the key fob, the passive key fob, for example, attenuates the alternating electromagnetic field. This attenuation can be detected by the key fob. Active key fobs, on the other hand, have a power source, such as a battery, which powers the corresponding circuitry.Active key fobs can therefore send data to a key fob lock in the conventional sense, and the range of the wireless data link can be correspondingly greater. Typical ranges can be up to 50 meters or more. With some active key fobs, authorization verification is only carried out after a user has issued a command. This command is usually transmitted via a button attached to the key fob. Alternatively, active key fobs, like passive key fobs, can establish a wireless data link with at least one corresponding key fob lock as soon as the two components (i.e., key fob lock and key fob) are within mutual transmission and reception range, i.e., within the range of the wireless data link. In this case, authorization verification can take place without further prompting from a user.As soon as the user approaches the key fob with the active key fob, the radio data link is automatically established and the key fob's authorization is checked. Usually, the active key fob doesn't transmit continuously, but first waits for a signal from the key fob, to which it then responds. If the key fob has the necessary authorization, the key fob unlocks, and the user can then, for example, open a door without noticing the authorization check.

[0004] Remote key fobs are therefore very convenient to use. With a sufficient range for the wireless data transmission (e.g., 50 cm or more), it is enough to simply carry the key fob with you when approaching the remote lock. If the key fob has the necessary authorization, you can easily open the corresponding door. In the best-case scenario, the user doesn't even notice that the remote lock has been unlocked.

[0005] German patent DE 199 27 253 A proposes equipping a transponder of a vehicle locking system with a motion sensor. Authentication by the transponder is only carried out if movement of the transponder is detected within a predefined time interval.

[0006] To determine whether an authorized user is approaching the tailgate of a vehicle equipped with a "keyless go system," German patent DE 10 2006 015 930 A1 proposes first checking the authorization of a transponder key when it approaches. If the key is authorized, the signal strength is then determined as a function of time to ascertain whether the user is approaching the tailgate. The tailgate is only opened if the user is approaching.

[0007] The subject of US patent 2012 / 0167684 A1 is the detection of complex movements in space using a selective motion sensor. For this purpose, a motion detection unit evaluates the measurement signals from a three-axis inertial sensor, a three-axis gyroscope, and a three-axis magnetic field sensor.

[0008] JP 2010 167 973 A discloses a method designed to prevent a vehicle key from being left in the vehicle after the driver has exited. For this purpose, the vehicle key has a capacitive proximity sensor configured to detect the distance between the key and the driver. If the vehicle is stationary and the driver leaves the vehicle without taking the vehicle key, a warning signal can be generated.

[0009] From DE 10 2005 012 326 A1, an electronic key with switching elements is known, wherein these are protected by a membrane formed from a soft component and surrounded by a supporting frame. The switching elements consist of a wear-free Hall sensor or a capacitive sensor.

[0010] A capacitive sensor is a sensor that operates based on the change in electrical capacitance of a single capacitor or a capacitor system. Different types of capacitive sensors exist: In one type, a plate is displaced or deformed by the effect being measured, thereby changing the plate separation and thus the electrically measurable capacitance. Alternatively, the effective plate area can change, for example, by moving the plates relative to each other, as in a variable capacitor. In capacitive touchscreens, the plate separation is fixed, and the capacitance changes because an electrically conductive material (finger) is brought into close proximity. [https: / / de.wikipedia.org / wiki / Kapazitiver_Sensor, accessed on August 4, 2025] Description of the invention

[0011] The problem underlying the invention is to make the use of radio keys in locking systems more secure.

[0012] This problem is solved by the method according to claim 1. Advantageous embodiments of the invention are specified in the dependent claims.

[0013] The invention is based on the observation that it is very convenient when a key fob unlocks a wireless lock without any further action required from the user, simply by approaching the lock with the key fob. The user then simply carries the key fob with them, for example, in a handbag or jacket pocket. Because the lock and key fob communicate with each other automatically and unlock the door as soon as the key fob is close enough to the lock for authorization verification, the user will carry the key fob without giving it any further thought. On the other hand, if the key fob is left near the door, i.e., on a coat rack within range of the wireless signal, it could lead to the door being opened by anyone.A typical scenario would be hanging a jacket or handbag on a coat rack near a key fob lock, with the key fob remaining in the bag. It's also possible to artificially extend the range of the wireless signal using repeaters. If unauthorized individuals do this, they can open the door without stealing the key. Simply placing a repeater within range of the key is sufficient. Typically, another repeater is then placed within range of the lock itself to ensure that the lock and key communicate with each other via the repeaters.

[0014] The method for unlocking a wireless lock (hereinafter also referred to as "lock") with a wireless key (hereinafter also referred to as "key") can comprise at least the following steps: It is detected, i.e., checked, whether the wireless key is being moved within the room or not. This step is also referred to as a movement check. An accelerometer is preferably used for this movement check. If the wireless key is moved, it can be ruled out that it was placed near the door lock. Therefore, if the wireless key is moved, or was moved within a defined, preferably short, time interval, the wireless lock is unlocked, provided the wireless key is authorized. As far as security is concerned, it is irrelevant whether an authorization check or a check to see if the wireless key is being moved is performed first.However, if the motion check is performed first, the authorization check can be omitted in some cases, and energy consumption is reduced accordingly. Ideally, release should not only occur when the key fob is currently being moved, but also if it was moved within a given time period, e.g., within the last minute, 20 seconds, or 10 seconds. The time period should be chosen so that undetected intrusion by a third party is unlikely, as it can be assumed that the user is still in the immediate vicinity of the key fob. Therefore, the time period can preferably be selected during the setup of the remote lock and / or the key fob, for example, based on the spatial conditions.

[0015] If the radio key is not moved within the given time period, i.e., no movement of it is detected, the radio lock will not be released even if the radio key is authorized.

[0016] To detect whether the key fob is being moved, a measure of the received field strength of the (at least two) signals emitted by the key fob could be determined. In other words, a change in the received field strength of the electromagnetic field emitted by the key fob at the key fob's location is detected as a function of time. Alternatively, the key fob could use at least two measurements of the received field strength of at least two signals emitted by the key fob to determine whether it is being moved relative to the key fob. Movement of the key fob relative to the key fob can be interpreted as movement of the key fob within the room, because a locked key fob is generally stationary.

[0017] A suitable measure for the received signal strength is, for example, the so-called RSSI (Received Signal Strength Indicator), which can be queried by most transponder chips available on the market as a standard feature. The key fob can therefore, for example, determine the RSSI of the electromagnetic field emitted by the key fob as a measure of the received signal strength, and / or the key fob can determine the RSSI of the electromagnetic field emitted by the key fob as a measure of the received signal strength. If the corresponding measure changes as a function of time, the key fob is moved. Preferably, the key fob is only unlocked if the change in the measure indicates an increase in the received signal strength, because then the key fob moves towards the key fob. If the received signal strength decreases, then the key fob moves away from the key fob, and the key fob should preferably remain closed (i.e., not unlocked).

[0018] Evaluating the received field strength as a function of time has two serious disadvantages: firstly, increased energy consumption, and secondly, the possibility that an increasing received field strength over time during a "repeater attack" could be generated by a correspondingly increasing transmitted field strength of the repeater, thus simulating movement.

[0019] Therefore, according to the invention, at least one acceleration sensor arranged on the key fob is preferably read to detect whether the key fob is being moved in space or not. If the acceleration sensor measures acceleration, this can be interpreted as movement of the key fob, because key fobs are generally not moved uniformly when carried by a moving user. For example, when the user walks, a key fob stored in a jacket pocket, for instance, moves not only in the direction of the movement but also alternately up and down. A walking movement can thus be detected based on a pattern in the acceleration as a function of time. Similarly, the movements of wheelchair users, for example, are only seemingly uniform. Furthermore, a user will always at least reduce their speed in front of a locked door, which can be measured as acceleration.Even perfectly uniform motion can be detected by an accelerometer, because the key fob must accelerate, at least initially. When it decelerates, this is also measurable as acceleration, but with the opposite sign. Integrating the acceleration yields the velocity. If the integral of the acceleration is not zero, the key fob is moving (provided it was at rest at the start of the measurement). Alternatively or additionally, the key fob can have at least a motion sensor and / or a position sensor. These sensors also allow for simple motion detection.

[0020] If it is detected that the key fob is stationary, the key fob and / or the key fob lock will preferably switch to energy-saving mode. Alternatively, the key fob may only switch to energy-saving mode after a specified period of time. In this energy-saving mode, the transmission power of the key fob lock and / or the key fob can be reduced. Preferably, the key fob will not transmit at all in energy-saving mode (transmission power is zero). As far as the key fob is concerned, it should only exit energy-saving mode when movement of the key fob is detected or the user activates the key fob via an input device, as there is no point in the key fob communicating with a key fob lock before this occurs. Alternatively, the key fob lock can exit energy-saving mode in response to a wake-up signal from the key fob lock.In locking systems with exclusively active remote keys, the remote lock can also reduce its transmission power to zero in energy-saving mode. However, in this mode, the signal level of a receiving antenna, such as an auxiliary antenna, of the remote lock should be monitored. As soon as the signal level at the receiving antenna exceeds a predetermined value, this can indicate the presence of a remote key within range. The remote lock should then "wake up" from energy-saving mode, which is a kind of sleep state, i.e., switch to a mode that allows authorization verification of the remote key. Both the remote lock and the remote key should, in their respective energy-saving modes, only supply power to the systems necessary to exit energy-saving mode, for example, in response to a wake-up signal, movement, etc. All other systems (e.g., signal boosters) should preferably be switched off.The frequency at which a microprocessor, usually used for control and coding, is clocked can also be reduced to a minimum.

[0021] Alternatively or additionally, a magnetic field sensor can be integrated into the key fob to monitor its movement. Similar to a compass, this sensor determines the magnetic field in which the key fob is located. When the key fob moves, this change is measurable as a change in the magnetic field, i.e., its direction and / or strength.

[0022] According to the invention, part of the key fob is designed as a capacitive sensor that can detect whether the key fob is being held, for example, in a hand. If the key fob is being held, it can also be ruled out that it was unintentionally placed near the key fob lock. If authorized, the key fob lock would then be unlocked (see claim 1). The key fob preferably has a housing in which the key fob's circuitry is at least partially housed. Preferably, at least two, and more preferably, a plurality of capacitor pads are arranged on the housing. By measuring the capacitance of the capacitors formed by the capacitor pads, it can be determined whether the key fob is being held by a user or not.

[0023] The above description assumes that the wireless lock is not enabled in the initial state and that it can only be operated after being enabled. Operation can consist of unlocking (opening) or locking a door.

[0024] Likewise, a switching process can also be enabled, e.g., switching a machine on and / or off. Description of the drawings

[0025] The invention is described below by way of example, without limiting the general concept of the invention, with reference to the drawings. Fig. Figure 1 shows a flowchart of a procedure for releasing a radio lock. Fig. Figure 2 shows a flowchart of another procedure for releasing a radio lock.

[0026] In the procedure according Fig. 1. A component of an electromechanical locking system, for example, an electromechanical wireless lock 10, communicates with a wireless key 20 according to a given communication protocol, i.e., one known to both the wireless lock 10 and the data carrier 20. The wireless key 20 can, for example, have a so-called "active transponder," i.e., be an active wireless key. This is shown in the drawing as "RFID card 20." The wireless lock 10 is shown here as an example of a knob cylinder. Both the wireless key 20 and the wireless lock 10 have transmitting and receiving means to establish a contactless data link between the wireless lock 10 and the wireless key 20. For the data link to be established successfully, the wireless lock 10 and the wireless key 20 must be brought close to each other. The maximum distance that must be maintained depends on the selected transmitting and receiving means as well as the specific spatial conditions.

[0027] The key fob 20 monitors, for example by evaluating signals from an accelerometer, whether it is being moved in the room (step 21). If "yes," it sends a wake-up signal (step 22). If this wake-up signal is received by a key fob 10 (step 11, yes), then the key fob 10 sends a reply signal (step 12). If not (step 11, no), the key fob 10 checks again whether it is receiving a wake-up signal. If the reply signal has been sent (step 12), it is received by the key fob 20 (step 23, yes), provided the key fob 10 and the key fob 20 are sufficiently close to each other. Now a radio data link is established between the key fob 10 and the key fob. This is also often referred to as a "handshake." The key fob 10 and the key fob then execute a protocol to verify the key fob's authorization and, if necessary, to release the key fob (steps 14, 24 "authorization check").For this purpose, data 33 is transmitted at least from the key fob 20 to the lock 10, but usually also from the lock 10 to the key fob 20. If the key fob does not receive a response signal from a lock (step 23, "No"), step 21, i.e., monitoring whether the key fob is moved, is executed again. Regardless of whether the lock fob was released as a result of the authorization check or not, the lock fob can enter an energy-saving mode, also known as sleep mode, after the authorization check 14, 24 and wait again for a wake-up signal from a key fob. Other signals can also be used as wake-up signals, e.g., the activation of a button and / or switch, or the detection of a change in capacitance (so). The energy-saving mode is characterized by the lock fob's reduced power consumption. For example, this can be achieved by...Parts of the microprocessor, which is usually used for control, are switched off and / or the clock rate of the microprocessor is reduced. In addition, the transmission power is preferably reduced, preferably to zero.

[0028] The procedure according Fig. The principle is that the key fob only establishes communication with the lock (without which unlocking the lock is impossible) if movement of the key fob within the room is detected within a predetermined time period. This prevents unnecessary communication, making attacks on the lock more difficult and reducing the energy consumption of both the lock (10) and the key fob (20). If the key fob is placed within range of the radio data link, no movement of the key fob (20) within the room is detected, and the radio data link is not established. Consequently, the lock, and thus the secured door, remains locked. As soon as the user picks up the key fob (20), the radio data link is established, the authorization check is performed, and the user, if authorized, can pass through the door.

[0029] One variant of the procedure is in Fig. 2. The procedure differs from the procedure according to Fig. 1. In particular, the check to determine whether the key fob is being moved in the room is carried out by measuring changes in the received signal strength of the respective communication partner as received by the key fob and / or the key fob. As usual, a data link is first established between the key fob 10 and the key fob 20. This is symbolized by steps 16 and 26. If the data link cannot be established, the attempt is repeated until it succeeds (step 26: Yes and step 16: Yes). Subsequently, an authorization check 24 and 14 is carried out as usual. However, unlike the procedure according to... Fig. 1. Either the remote lock determines a measure of the received field strength of the radio signal emitted by the remote lock as a function of time, and / or the remote lock determines a measure of the received field strength of the response signal emitted by the remote key as a function of time (steps 27, 17). The variant shown is one in which both the remote lock and the remote key determine the received field strength of their respective communication partners; however, it is sufficient if only one of the two communication partners, i.e., remote key 20 or remote lock 10, determines the corresponding measure. The data 33 exchanged for this purpose can be part (or all) of the data to be exchanged according to the authorization check protocol. In the following step 21, 18 (Yes, No), it is determined, based on the previously determined measure of the respective received field strength, whether the remote key was moved within the measurement period.To do this, it suffices to check whether the measurement of one or both received field strengths exhibits a gradient greater than a predefined value. If the gradient is positive, then the received field strength increased between the measurements from which the gradient was calculated, from which it can be concluded that the distance between key fob 20 and remote lock 10 has decreased. This information can be exchanged between the communication partners, i.e., between remote lock 10 and key fob 20. If key fob 20 has been moved (steps 21, 18 "Yes"), then the authorization check continues, and if the key fob is authorized, the remote lock is released. If the key fob has not been moved (steps 21, 18 "No"), then the authorization check can be terminated because the remote lock must not be released.Wireless lock 10 and wireless key 20 then attempt to establish a data connection, preferably with other possible communication partners (return to the beginning). In the example, after... Fig. Steps 18 and 21 are carried out as part of the authorization check because a measure of the received field strength of data 33 is used for authorization verification to detect whether the radio key was moved within a specified time period. Of course, other data, such as random numbers, can also be sent to determine the received field strength. Reference symbol list 10 wireless locks 11. Did you receive the wake-up signal? Yes / No 12. Send response signal 14. Eligibility check 15 Transition to energy saving mode 16 Handshake / Data link established successfully Yes / No 17 Communication with RSSI measurement 18. Movement test; testing the movement of the key fob in the room? Yes / No 19 Eligibility check 20 keys / RFID card 21. Movement test; testing the movement of the key fob in the room? Yes / No 22 Send alarm signal, 23. Test: Response signal received? Yes / No 24. Eligibility check 27 Communication with RSSI measurement 29 Eligibility check 33 Data exchange for authorization checks 35 Information exchange Result of the examination of steps 21, 18

Claims

[1] Method for unlocking a wireless lock (10) with a wireless key (20), wherein the wireless lock (10) and the wireless key (20) communicate with each other without the intervention of a user, characterized by , that - with a capacitive sensor, which forms at least part of the radio key (20), detects whether the radio key (20) is being held by the user, - the radio lock (10) will only be released if the radio key (20) is held and the radio key (20) is authorized to release the radio lock (10). [2] Radio key (20) for use in the method according to claim 1, characterized by , that the radio key (20) has a capacitive sensor. [3] Radio key (20) according to claim 2 or for use in the method according to claim 1, characterized by , that the radio key (20) has at least two capacitor surfaces on a housing.

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