SE2251583A1 - Controlling an energy path to a lock actuator - Google Patents

Abstract

It is provided a method for controlling an energy path to a lock actuator (7) of an electronic lock (1) further comprising: an access control module (3), a generator (4), and a switch (6) between the generator (4) and the lock actuator (7). The method is performed by the electronic lock (1). The method comprises: performing (40) an access evaluation in communication with an electronic key (2), wherein the access control module is configured to be powered by the electronic key (2) over a first energy path (11); determining (42) that the access evaluation is positive; and controlling (44) the switch (6) to close a second energy path (12) from the generator (4) to the lock actuator (7), such that energy from the generator (4) causes the lock actuator (7) to set the electronic lock (1) in an unlocked state.

Description

TECHNICAL FIELD id="p-1" id="p-1" id="p-1" id="p-1"

[0001] The present disclosure relates to the field of electronic locks, and in particular to controlling an energy path to a lock actuator to thereby control a lock state of the electronic lock.

BACKGROUND id="p-2" id="p-2" id="p-2" id="p-2"

[0002] Locks and keys are evolving from the traditional pure mechanical locks. These days, electronic locks are becoming increasingly common. For electronic locks, no mechanical key profile is needed for access evaluation of a user. The electronic locks can e.g. be opened using an electronic key stored on a special carrier (fob, card, etc.) or in a smartphone. The electronic key and electronic lock can e.g. communicate over a wireless interface. Such electronic locks provide a number of benefits, including improved flexibility in management of access rights, audit trails, key management, etc. id="p-3" id="p-3" id="p-3" id="p-3"

[0003] However, electronic locks need to be provided with electric power. One way is to hardwire a power supply to the lock. While this is reliable, installation complexity and costs are rather high. Alternatively, electronic locks can be battery powered. However, batteries run out after a certain time and then need to be replaced, which is inconvenient. id="p-4" id="p-4" id="p-4" id="p-4"

[0004] There are electronic locks that are powered by an NFC (Near-Field Communication) enabled smartphone. Energy is then transmitted from the smartphone to the electronic lock. However, the amount energy supplied using NFC is not sufficient to power all types of electronic locks.

SUMMARY id="p-5" id="p-5" id="p-5" id="p-5"

[0005] One object is to provide an electronic lock with an access control module that can be used for different types of lock actuators. id="p-6" id="p-6" id="p-6" id="p-6"

[0006] According to a first aspect, it is provided a method for controlling an energy path to a lock actuator of an electronic lock further comprising: an access control module, a generator, and a switch between the generator and the lock actuator. The method being is performed by the electronic lock. The method comprises: performing an access evaluation in communication with an electronic key, wherein the access control module is configured to be powered by the electronic key over a first energy path; determining that the access evaluation is positive; and controlling the switch to close a second energy path from the generator to the lock actuator, such that energy from the generator causes the lock actuator to set the electronic lock in an unlocked state. [0007] The first energy path may be separate from the second energy path. id="p-8" id="p-8" id="p-8" id="p-8"

[0008] The first energy path may be based on near-field communication, NFC, or radio frequency identification, RFID. id="p-9" id="p-9" id="p-9" id="p-9"

[0009] The controlling may comprise the access control module providing a control signal to the switch. id="p-10" id="p-10" id="p-10" id="p-10"

[0010] The electronic lock may be configured to maintain the switch in a state to connect the generator with the lock actuator for a period of time from receiving the control signal, even when the control signal has ended. [0011] The controlling may comprise closing the switch. id="p-12" id="p-12" id="p-12" id="p-12"

[0012] According to a second aspect, it is provided an electronic lock for controlling an energy path to a lock actuator. The electronic lock comprises: an access control module; a generator; the lock actuator; and a switch between the generator and the lock actuator. The access control module comprises a processor; and a memory storing instructions that, when executed by the processor, cause the access control module to: perform an access evaluation in communication with an electronic key, wherein the access control module is configured to be powered by the electronic key over a first energy path; determine that the access evaluation is positive; and control the switch to close a second energy path from the generator to the lock actuator, such that energy from the generator causes the lock actuator to set the electronic lock in an unlocked State. id="p-13" id="p-13" id="p-13" id="p-13"

[0013] The first energy path from the generator to the lock actuator may be separate from the second energy path. 3 id="p-14" id="p-14" id="p-14" id="p-14"

[0014] The first energy path may be based on near-field communication, NFC, or radio frequency identification, RFID. id="p-15" id="p-15" id="p-15" id="p-15"

[0015] The controlling may comprise the access control module providing a control signal to the switch. id="p-16" id="p-16" id="p-16" id="p-16"

[0016] The electronic lock may be configured to maintain the switch in a state to connect the generator with the lock actuator for a period of time from receiving the control signal, even when the control signal has ended. [0017] The controlling may comprise closing the switch. id="p-18" id="p-18" id="p-18" id="p-18"

[0018] The generator may be implemented using a stepper motor, in which case the lock actuator is implemented using a stepper motor. id="p-19" id="p-19" id="p-19" id="p-19"

[0019] According to a third aspect, it is provided a computer program for controlling an energy path to a lock actuator. The computer program comprises computer program code which, when executed on an electronic lock comprising: an access control module; a generator; the lock actuator; and a switch between the generator and the lock actuator; causes the electronic lock to: perform an access evaluation in communication with an electronic key, wherein the access control module is configured to be powered by the electronic key over a first energy path; determine that the access evaluation is positive; and control the switch to close a second energy path from the generator to the lock actuator, such that energy from the generator causes the lock actuator to set the electronic lock in an unlocked state. id="p-20" id="p-20" id="p-20" id="p-20"

[0020] According to a fourth aspect, it is provided a computer program product comprising a computer program according to the third aspect and a computer readable means comprising non-transitory memory in which the computer program is stored. id="p-21" id="p-21" id="p-21" id="p-21"

[0021] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/ an /the element, apparatus, component, means, step, etc." are to be interpreted openly as referring at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. 4 BRIEF DESCRIPTION OF THE DRAWINGS id="p-22" id="p-22" id="p-22" id="p-22"

[0022] Aspects and embodiments are now described, by way of example, with refer- ence to the accompanying drawings, in which: id="p-23" id="p-23" id="p-23" id="p-23"

[0023] Fig 1 is a schematic diagram illustrating an environment in which embodiments presented herein can be applied; id="p-24" id="p-24" id="p-24" id="p-24"

[0024] Fig 2 is a schematic diagram illustrating an embodiment of the electronic lock of Fig 1; and id="p-25" id="p-25" id="p-25" id="p-25"

[0025] Fig 3 is a flow chart illustrating embodiments of methods for controlling an energy path to a lock actuator of electronic lock; id="p-26" id="p-26" id="p-26" id="p-26"

[0026] Fig 4 is a schematic diagram illustrating components of the electronic lock 1 of Fig 1; and id="p-27" id="p-27" id="p-27" id="p-27"

[0027] Fig 5 shows one example of a computer program product 90 comprising computer readable means.

DETAILED DESCRIPTION id="p-28" id="p-28" id="p-28" id="p-28"

[0028] The aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. These aspects may, however, be embodied in many different forms and should not be construed as limiting; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and to fully convey the scope of all aspects of invention to those skilled in the art. Like numbers refer to like elements throughout the description. id="p-29" id="p-29" id="p-29" id="p-29"

[0029] Embodiments presented herein are based on an electronic lock being provided with two energy paths. A first energy path is provided from the electronic key (e.g. smartphone) to an access control module. A second energy path is provided from a generator to a motor that, when operated, unlocks (or locks) the electronic lock. A switch is provided between the generator and the motor on the second energy path. When the access control module grants access based on evaluating a provided electronic key, the switch is controlled to close the second energy path, resulting in the electronic lock being set in an unlocked state when the generator is rotated. By separating the two energy paths, the electronic key only needs to power the access control module, and not the motor. This allows the access control module to be reused for different implementations where the energy requirements for the lock actuator can vary greatly. By using the generator to power the motor, no energy needs to be stored between the generator and the lock actuator. Furthermore, there is no need to have a mechanical connection between the generator and motor, thus providing a mechanically more secure solution. id="p-30" id="p-30" id="p-30" id="p-30"

[0030] Fig 1 is a schematic diagram illustrating an environment in which embodiments presented herein can be applied. Access to a restricted physical space 16 is restricted by an openable physical barrier 15 which is selectively unlockable. The physical barrier 15 stands between the restricted physical space 16 and an accessible physical space 14. Note that the accessible physical space 14 can be a restricted physical space in itself, but in relation to this physical barrier 15, the accessible physical space 14 is accessible. The barrier 15 can be a door, gate, hatch, cabinet door, drawer, window, etc. An electronic lock 1 is provided in order to control access to the physical space 16, by selectively unlocking the barrier 15. A door actuator 8, such as a handle or doorknob, is provided to allow the user 5 to open the physical barrier 15, e.g. by rotating the door actuator 8. id="p-31" id="p-31" id="p-31" id="p-31"

[0031] The electronic lock 1 can be provided in a structure 17 (such as a wall) surrounding the barrier 15 (as shown) or the electronic lock 1 can be provided in the barrier 15 itself (not shown). The electronic lock 1 is controllable to be in a locked state or in an unlocked state, as shown and described in more detail below. id="p-32" id="p-32" id="p-32" id="p-32"

[0032] A user 5 carries an electronic key 2. The electronic key 2 can be in any suitable format that allows the electronic lock 1 to communicate (wirelessly or conductively) with the electronic key to evaluate whether to grant access. For instance, the electronic key 2 can be in the form of a key fob, a key card, a hybrid mechanical/ electronic key or embedded in a smartphone. Depending on the access rights evaluated by the electronic lock 1 for the electronic key 2, the electronic key 2 can be used to unlock the electronic lock 1. The electronic key 2 provides power to the electronic lock 1, e.g. using NFC or a galvanic connection. id="p-33" id="p-33" id="p-33" id="p-33"

[0033] Fig 2 is a schematic diagram illustrating an embodiment of the electronic lock 1 of Fig 1. The electronic lock 1 comprises a generator 4 and a lock actuator 7, and a switch 6 provided therebetween. The generator 4 can be implemented as a stepper motor, in which case the stepper motor operates in generator mode. Also the lock actuator 7 can be implemented as a stepper motor. This implementation provides motion of the lock actuator 7 that is synchronous with the motion of the generator 4. id="p-34" id="p-34" id="p-34" id="p-34"

[0034] In general, the generator 4 can be any type of generator suitable for use in the electronic lock, and can e.g. be any type of rotating electrical machine (e.g. a DC motor) that is also usable in generator mode. id="p-35" id="p-35" id="p-35" id="p-35"

[0035] Alternatively, the lock actuator 7 is implemented using a solenoid. The switch 6 is implemented using any suitable electronically controllable switch, e.g. one or more transistors and/ or thyristors, e.g. in the form of a power switch. id="p-36" id="p-36" id="p-36" id="p-36"

[0036] An access control module 3 comprises an antenna 20 and a processor 60. The access control module 3 is configured to evaluate access for an electronic key 2 in communication via a radio signal with the access control module 3 via the antenna 20. The antenna 20 can also collect energy from the radio signal from the electronic key 2, to thereby power the access control module 3. Energy is thereby supplied from the electronic key 2 to the access control module 3 via a first energy path 11. The first energy path 11 can be based e.g. on RFID (Radio Frequency Identification) and/ or NFC (Near- Field Communication), where the electronic key 2 is an inquiring entity and the electronic lock 1 is a responding entity. The access control module 3 can be implemented based on an NFC smartcard with the addition of a single GPIO output, allowing the access control module 3 to be implemented at a very low component cost. Alternatively, the access control module 3 receives power from the electronic key 2 over a galvanic connection (not shown). id="p-37" id="p-37" id="p-37" id="p-37"

[0037] When access is granted, evaluated by the processor 60 of the access control module 3, the processor 60 transmits a control signal to the switch 6, to thereby close a second energy path 12 from the generator 4 to the lock actuator 7. The output from the access control module 3 can implemented by setting a GPIO (General-purpose input/ output) pin to a predefined state, e.g. HIGH or LOW. The energy path 12 can be a DC (Direct Current) connection. The switch 6 enables the access control module 3 to control the second energy path 12 to the lock actuator 7, and thus to control the lock state of the electronic lock 1. The granted access can also be communicated to the electronic key 2, which, e.g. when the electronic key 2 is implemented in a smartphone, 7 can indicate the granted access to the user 5, e.g. as a visual indication (on a screen), a sound and/ or a vibration on the smartphone. id="p-38" id="p-38" id="p-38" id="p-38"

[0038] Hence, there is a separation between the first energy path 11 in which the electronic key 2 powers the access control module 3, and the second energy path 12 in which the generator 4 powers the lock actuator 7 (when the electronic lock 1 is to be unlocked). id="p-39" id="p-39" id="p-39" id="p-39"

[0039] In order to unlock the lock, (optionally after being notified of the granted access when the electronic key 2 is a smartphone) the user causes the generator 4 to rotate, e.g. by turning the door actuator 8 (e.g. handle, doorknob) that is mechanically connected to the generator. Alternatively, there is thumb turn (mechanically connected to the generator 4) that is provided on the side of the accessible physical space 14 (see Fig 1), in which case the user simply rotates the thumb turn to cause the generator 4 to rotate. Optionally, a gearbox can be provided between the user motion device and the generator to control (e.g. increase) rotational speed of the generator. Such a gearbox can improve efficiency of the generator, e.g. if a DC motor is used as a generator. The user action that causes the generator 4 to rotate generates electric energy that is transferred over the second energy path 12 to the lock actuator 7 to unlock the electronic lock 1 (when the access control module 3 has granted access). id="p-40" id="p-40" id="p-40" id="p-40"

[0040] Since the user action is separate (energy-wise) from the access control and there is separation between the first energy path 11 and the second energy path 12, the access control module 3 does not need to supply power to actuate the lock actuator 7; this is achieved using the generator 3. Nevertheless, it is the access control module 3 that controls if power generation from the access control module 3 is to reach the lock actuator 7. In this way, the access control module 3 can be implemented in the same way for a wide range of different lock types with varying power requirements for the lock actuator 7. The access control module 3 can thus be used to provide NFC-based access control for virtually any type of electronic lock 1. Only the generator 4 and the switch 6 need to be dimensioned with the requirements of the lock actuator 7 in mind. Furthermore, in embodiments presented herein, hard power wiring and batteries can be avoided in the electronic lock 1. id="p-41" id="p-41" id="p-41" id="p-41"

[0041] Additionally, there is no need to have a mechanical connection between the generator and motor. The generator 4 is provided in the accessible physical space 14, 8 while the lock actuator 7 is provided in the restricted physical space 16. By completely separating the generator 4 and the lock actuator 7 mechanically, a high torque or high rotational speed of the generator 4 is not necessarily mechanically transferred to M and can thus be controlled to only affect the state of the lock within predefined parameters. Such parameters can be implicit based on limitations of the generator 4 and/ or the lock actuator 7, thus limiting the transfer of potentially destructive mechanical force. This drastically reduces the ability of an attacker to mechanically force open the electronic lock 1. id="p-42" id="p-42" id="p-42" id="p-42"

[0042] A user scenario will now be presented to illustrate the function of the electronic lock 1, in which the electronic key 2 is implemented in a smartphone. When the user 5 arrives to the electronic lock 1, the user 5 taps the electronic key 2 (in the form of a smartphone) against the antenna 20. This transfers energy from the smartphone (using NFC) to the access control module 3 and the processor 60 is powered up. The access control module 3 communicates with the smartphone to evaluate whether to grant access. When access is granted, the access control module 3 sends a control signal to the switch 6 to connect the generator 4 and the lock actuator 7. The access control module 3 also sends a grant notification to the smartphone, causing the smartphone to display a message/ symbol that access is granted, and a little sound is played. The user 5 turns the door actuator 8, in the form of a doorknob, which is mechanically connected to the generator 4. This causes the generator 4 to generate electrical energy that flows (via the conducting switch 6) to the lock actuator 7, causing the lock actuator 7 to turn to unlock the electronic lock 1. id="p-43" id="p-43" id="p-43" id="p-43"

[0043] Fig 3 is a flow chart illustrating embodiments of methods for controlling an energy path to a lock actuator 7 of electronic lock 1. As shown in Fig 2 and described above, the electronic lock 1 comprises: an access control module 3, a generator 4, and a switch 6 between the generator 4 and the lock actuator 7. id="p-44" id="p-44" id="p-44" id="p-44"

[0044] In an access evaluation step 40, the electronic lock 1 performs an access evaluation in communication with an electronic key 2, wherein the access control module is configured to be powered by the electronic key 2 over a first energy path 11. The access evaluation can be performed e.g. by checking the identity of the electronic key 2 against a list of identities that are to be given access. Alternatively or additionally, the electronic key 2 is authenticated by proving ownership of a secret shared between 9 the electronic key 2 and the electronic lock 1. Alternatively or additionally, the electronic lock 1 checks whether the electronic key 2 has been delegated access by an entity that is trusted by the electronic lock 1 (e.g. verified using a cryptographic signature). id="p-45" id="p-45" id="p-45" id="p-45"

[0045] The first energy path 11 can e.g. be based on NFC or RFID, where radio waves from the electronic key 2 thereby powers the access control module 3. id="p-46" id="p-46" id="p-46" id="p-46"

[0046] In a conditional positive step 42, the electronic lock 1 determines whether the access evaluation in the preceding step was positive or not. When the access evaluation is positive, the method proceeds to a close 2nd energy path step 44. Otherwise, the method ends. id="p-47" id="p-47" id="p-47" id="p-47"

[0047] In the close 2nd energy path step 44, the electronic lock 1 controls the switch 6 to close a second energy path 12 from the generator 4 to the lock actuator 7. In this way, energy from the generator 4 causes the lock actuator 7 to set the electronic lock 1 in an unlocked state. As explained above, the first energy path 11 is separate from the second energy path 12. id="p-48" id="p-48" id="p-48" id="p-48"

[0048] The controlling can be implemented by the access control module 3 providing a control signal to the switch 6, to thereby close the second energy path 12 from the generator 4 to the lock actuator 7. For instance, the controlling can comprise closing the switch, i.e. setting the switch in a conducting state. id="p-49" id="p-49" id="p-49" id="p-49"

[0049] In one embodiment, the electronic lock 1 is configured to maintain the switch 6 in a state (e.g. conductive state) to connect the generator 4 with the lock actuator 7 for a period of time from receiving the control signal, even when the control signal has ended. In other words, the second energy path 12 is kept conducting for a period of time (e.g. a number of seconds) after access is granted, to allow the user to perform the user action to cause the generator 4 to rotate. In this way, the user does not need to keep the smartphone by the antenna 20 after access is granted to keep the second energy path 12 closed. This embodiment may require a limited amount of energy stored in a capacitor to maintain the state of the switch 6. The embodiment could optionally use a fraction of the energy produced by the generator 4 to maintain the state of the switch for a small period of time even if the access control module 3 is inactive and not powered. 1O id="p-50" id="p-50" id="p-50" id="p-50"

[0050] Fig 4 is a schematic diagram illustrating components of the electronic lock 1 of Fig 1. The components shown in Fig 4 can be implemented in the access control module 3 (see Fig 2) of the electronic lock 1. A processor 60 is provided using any combination of one or more of a suitable central processing unit (CPU), graphics processing unit (GPU), multiprocessor, neural processing unit (NPU), microcontroller, digital signal processor (DSP), etc., capable of executing software instructions 67 stored in a memory 64, which can thus be a computer program product. The processor 60 could alternatively be implemented using an application specific integrated circuit (ASIC), field programmable gate array (FPGA), etc. The processor 60 can be configured to execute the method described with reference to Fig 3 above. id="p-51" id="p-51" id="p-51" id="p-51"

[0051] The memory 64 can be any combination of random-access memory (RAM) and/ or read-only memory (ROM). The memory 64 also comprises non-transitory persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, or solid-state memory. id="p-52" id="p-52" id="p-52" id="p-52"

[0052] A data memory 66 is also provided for reading and/ or storing data during execution of software instructions in the processor 60. The data memory 66 can be any combination of RAM and/ or ROM. id="p-53" id="p-53" id="p-53" id="p-53"

[0053] The electronic lock 1 further comprises an I/ O interface 62 for communicating with external and/ or internal entities. id="p-54" id="p-54" id="p-54" id="p-54"

[0054] Other components of the electronic lock 1 are omitted in order not to obscure the concepts presented herein. id="p-55" id="p-55" id="p-55" id="p-55"

[0055] Fig 5 shows one example of a computer program product 90 comprising computer readable means. On this computer readable means, a computer program 91 can be stored in a non-transitory memory. The computer program can cause a processor to execute a method according to embodiments described herein. In this example, the computer program product is in the form of a removable solid-state memory, e.g. a Universal Serial Bus (USB) drive. As explained above, the computer program product could also be embodied in a memory of a device, such as the computer program product 64 of Fig 4. While the computer program 91 is here schematically shown as a section of the removable solid-state memory, the computer program can be stored in any way which is suitable for the computer program product, such as another type of removable 11 solid-state memory, or an optical disc, such as a CD (compact disc), a DVD (digital versatile disc) or a Blu-Ray disc. id="p-56" id="p-56" id="p-56" id="p-56"

[0056] The aspects of the present disclosure have mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims. Thus, while various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims (15)

Claims

1. A method for controlling an energy path to a lock actuator (7) of an electronic lock (1) further comprising: an access control module (3), a generator (4), and a switch (6) between the generator (4) and the lock actuator (7), the method being performed by the electronic lock (1), the method comprising: performing (40) an access evaluation in communication with an electronic key (2), wherein the access control module is configured to be powered by the electronic key (2) over a first energy path (11); determining (42) that the access evaluation is positive; and controlling (44) the switch (6) to close a second energy path (12) from the generator (4) to the lock actuator (7), such that energy from the generator (4) causes the lock actuator (7) to set the electronic lock (1) in an unlocked state.

2. The method according to claim 1, wherein the first energy path (11) is separate from the second energy path (12).

3. The method according to claim 1 or 2, wherein the first energy path (11) is based on near-field communication, NFC, or radio frequency identification, RFID.

4. The method according to any one of the preceding claims, wherein the controlling (44) comprises the access control module (3) providing a control signal to the switch (6).

5. The method according to claim 4, wherein the electronic lock (1) is configured to maintain the switch (6) in a state to connect the generator (4) with the lock actuator (7) for a period of time from receiving the control signal, even when the control signal has ended.

6. The method according to any one of the preceding claims, wherein the controlling (44) comprises closing the switch.

7. An electronic lock (1) for controlling an energy path to a lock actuator (7), the electronic lock comprising: an access control module (3); a generator (4); the lock actuator (7); and a switch (6) between the generator (4) and the lock actuator (7); wherein the access control module (3) comprises a processor (6o); and a memory(64) storing instructions (67) that, when executed by the processor, cause the access control module to: perform an access evaluation in communication with an electronic key (2), wherein the access control module is configured to be powered by the electronic key (2) over a first energy path (11); determine that the access evaluation is positive; and control (44) the switch (6) to close a second energy path (12) from the generator (4) to the lock actuator (7), such that energy from the generator (4) causes the lock actuator (7) to set the electronic lock (1) in an unlocked state.

8. The electronic lock (1) according to claim 7, wherein the first energy path (11) from the generator (4) to the lock actuator (7) is separate from the second energy path (12).

9. The electronic lock (1) according to claim 7 or 8, wherein the first energy path (11) is based on near-field communication, NFC, or radio frequency identification, RFID. 1o.

10.The electronic lock (1) according to any one of claims 7 to 9, wherein the controlling (44) comprises the access control module (3) providing a control signal to the switch (6).

11. The electronic lock (1) according to claim 10, wherein the electronic lock (1) is configured to maintain the switch (6) in a state to connect the generator (4) with the lock actuator (7) for a period of time from receiving the control signal, even when the control signal has ended.

12. The electronic lock (1) according to any one of claims 7 to 11, wherein the controlling (44) comprises closing the switch.

13. The electronic lock (1) according to any one of claims 7 to 12, wherein the generator (4) is implemented using a stepper motor and the lock actuator (7) is implemented using a stepper motor.

14. A computer program (67, 91) for controlling an energy path to a lock actuator (7), the computer program comprising computer program code which, when executed on an electronic lock (1) comprising: an access control module (3); a generator (4); the lock actuator (7); and a switch (6) between the generator (4) and the lock actuator (7); causes the electronic lock (1) to: perform an access evaluation in communication with an electronic key (2), wherein the access control module is configured to be powered by the electronic key (2)over a first energy path (11); determine that the access evaluation is positive; and control (44) the switch (6) to close a second energy path (12) from the generator (4) to the lock actuator (7), such that energy from the generator (4) causes the lock actuator (7) to set the electronic lock (1) in an unlocked state.

15. A computer program product (64, 90) comprising a computer program according to claim 14 and a computer readable means comprising non-transitory memory in which the computer program is stored.