Patent Application
20250111972
This disclosure relates to magnetic systems and in particular to magnetic systems that are switchable between attractive and repulsive states.
Magnetic latches can be used to hold two components in a closed position, in which opposing surfaces abut or touch each other. For example, permanent magnets can be included in the base and the lid of a laptop computer. When the lid is brought into proximity to the base, the permanent magnets can provide an attractive force to latch the lid to the base without consuming power. The attractive force can be overcome by the user pushing on the lid to open it, while making it less likely that the lid will simply fall open, e.g., while the laptop is being transported. Further, magnetic latches that lack moving parts may be more durable than mechanical latches.
However, permanent magnets can produce an external magnetic field even while the laptop is open. Thus, for instance, permanent magnets in the base that are strong enough to be effective for latching the lid may produce a strong enough field to affect or damage other nearby devices or items (such as a credit card) when the lid is open.
Certain embodiments described herein relate to magnetic systems that can switch from an attractive to a repulsive magnetic force between components of the system. In some embodiments, the system may also have a neutral state in which little or no magnetic force is produced. A magnetic system can include a “fixed” magnet array that includes permanent magnets having fixed magnetic polarizations and a “switchable” magnet array that includes magnetic elements whose direction of magnetic polarizations can be switched into either of two opposing directions, such as electropermanent magnets. The permanent magnets and the switchable magnetic elements can be arranged in their respective arrays such that, depending on the state of the switchable magnetic elements, either an attractive magnetic force or a repulsive magnetic force (or in some cases negligible magnetic force) is produced between the fixed magnet array and the controllable magnet array.
Certain embodiments described herein relate to magnetic systems that incorporate electropermanent magnets (EPMs) as the switchable magnetic elements. EPMs provide a magnetic field that can be switched on or off using a current pulse. A current pulse in one direction switches the EPM on; a pulse in the other direction switches the EPM off. An EPM can retain its magnetization state (on or off) after the current pulse ends. Accordingly, power is required only while the magnetization state is being changed.
According to some embodiments, a magnetic system can include an electropermanent array and a fixed magnet array. The controllable magnet array can include two or more electropermanent magnets placed end-to-end. Each electropermanent magnet can include a first permanent magnet disposed proximate to an interface surface and having a fixed magnetic orientation along a longitudinal axis; a switchable magnet comprising a core made of a magnetic material and a coil of wire wound around the core along a longitudinal axis of the core, with the switchable magnet positioned on a distal side of the first permanent magnet and spaced apart from the first permanent magnet; and pole pieces disposed at each longitudinal end of the first permanent magnet and the switchable magnet, where the pole pieces are made of a soft magnetic material and extended across end surfaces of the first permanent magnet and the electropermanent magnet. The fixed magnetic orientations of the first permanent magnets in adjacent electropermanent magnets can be antiparallel to each other, and pole pieces can be shared between adjacent electropermanent magnets in the controllable magnet array. The fixed magnet array can include second permanent magnets arranged parallel to the interface surface such that each second permanent magnet aligns with one of the pole pieces of the controllable magnet array. Adjacent second permanent magnets can have fixed magnetic polarizations in opposite directions toward or away from the interface surface. A control and driver circuit can be coupled to each of the coils and configured to supply current pulses to the coils to switch a direction of magnetic polarization of the cores of the electropermanent magnets, thereby switching the electropermanent magnets between an ON state in which a direction of magnetic polarization of the core is parallel to the magnetic polarization of the first permanent magnet and an OFF state in which the direction of magnetic polarization of the core is antiparallel to the magnetic polarization of the first permanent magnet. The control and driver circuit can be configured to supply current pulses to different coils at different times.
If the second permanent magnets are aligned relative to the first permanent magnets such that the direction of magnetization is parallel to the direction of flux through the pole pieces when the electropermanent magnets are in the ON state, an attractive magnetic force between the fixed magnet array and the controllable magnet array can be produced by switching the electropermanent magnets to the ON state. If, however, the second permanent magnets are aligned relative to the first permanent magnets such that the direction of magnetization is antiparallel to the direction of flux through the pole pieces when the electropermanent magnets are in the ON state, a repulsive magnetic force between the fixed magnet array and the controllable magnet array can be produced by switching the electropermanent magnets to the ON state. In some embodiments, a magnetic system can include a first section in which the second permanent magnets are aligned relative to the first permanent magnets such that attractive magnetic force is provided and a second section in which the second permanent magnets are aligned relative to the first permanent magnets such that repulsive magnetic force is provided. By selectively switching different EPMs on and off, the magnetic system can provide attractive force, repulsive force, or a neutral state (e.g., with all EPMs in the OFF state) at different times.
Magnetic systems of this kind can be deployed to selectively create attractive and/or repulsive magnetic forces between two objects or surfaces. As just one example, an EPM array can be disposed in the base of a laptop and oriented toward the lid while a fixed magnet array is disposed in the lid and oriented toward the base. By controlling the EPM array or portions thereof, different magnetic forces can be produced at different times. For instance, an attractive force can be created to help close the lid or to secure the lid in the closed position and/or a repulsive force can be created to pop the lid open (or ajar) from a closed position. The EPM array can also be switched off when magnetic force is not desired (e.g., when the laptop is open for use), thereby reducing stray magnetic fields.
According to some embodiments, a magnetic system can include an electropermanent array and a fixed magnet array. The controllable magnet array can include two or more electropermanent magnets placed end-to-end. Each electropermanent magnet can include a first switchable magnet disposed proximate to an interface surface and having a first core made of a magnetic material and a first coil of wire wound around the first core along a longitudinal axis of the first core, together with a second switchable magnet having a second core made of a magnetic material and a second coil of wire wound around the second core along a longitudinal axis of the second core, with the second switchable magnet being positioned on a distal side of the first switchable magnet and spaced apart from the first switchable magnet. Pole pieces can be disposed at each longitudinal end of the first switchable magnet and the second switchable magnet, where the pole pieces are made of a soft magnetic material and extend across end surfaces of the first switchable magnet and the second switchable magnet. Pole pieces can be shared between adjacent electropermanent magnets in the controllable magnet array. The fixed magnet array can include permanent magnets arranged parallel to the interface surface such that each permanent magnet aligns with one of the pole pieces of the controllable magnet array. Adjacent permanent magnets can have magnetic polarizations in opposite directions toward or away from the interface surface. A control and driver circuit coupled to each of the first coils and second coils and configured to supply current pulses to the first coils and second coils, thereby switching the electropermanent magnets among a first ON state in which the magnetic polarizations of the first and second switchable magnets are parallel and in a first longitudinal direction, a second ON state in which the magnetic polarizations of the first and second switchable magnets are parallel and in a second longitudinal direction opposite the first longitudinal direction, and an OFF state in which the magnetic polarizations of the first and second switchable magnets are in antiparallel longitudinal directions. The control and driver circuit can be configured to supply current pulses to different coils at different times.
The following detailed description, together with the accompanying drawings, will provide a better understanding of the nature and advantages of the claimed invention.
The following description of exemplary embodiments of the invention is presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the claimed invention to the precise form described, and persons skilled in the art will appreciate that many modifications and variations are possible. The embodiments have been chosen and described in order to best explain the principles of the invention and its practical applications to thereby enable others skilled in the art to best make and use the invention in various embodiments and with various modifications as are suited to the particular use contemplated.
Certain embodiments described herein relate to magnetic systems that can switch from an attractive to a repulsive magnetic force between components of the system. In some embodiments, the system may also have a neutral state in which little or no magnetic force is produced. A magnetic system can include a “fixed” magnet array that includes permanent magnets having fixed magnetic polarizations and a “switchable” magnet array that includes electropermanent magnetic elements whose direction of magnetic polarizations can be switched into either of two opposing directions. The permanent magnets and the switchable magnetic elements can be arranged in their respective arrays such that, depending on the state of the switchable magnetic elements, either an attractive magnetic force or a repulsive magnetic force (or in some embodiments negligible magnetic force) is produced between the fixed magnet array and the controllable magnet array.
Certain embodiments described herein relate to magnetic systems that incorporate electropermanent magnets (EPMs) as the switchable magnetic elements. EPMs provide a magnetic field that can be switched on or off using a current pulse. A current pulse in one direction switches the EPM on; a pulse in the other direction switches the EPM off. An EPM can retain its magnetization state (on or off) after the current pulse ends. Accordingly, power is required only while the magnetization state is being changed.
More specifically, EPM 110 includes a permanent magnet 112, a switchable magnet 114, and pole pieces 116. Permanent magnet 112 can be positioned proximate to an interface surface 107 (shown as a dashed line) while switchable magnet 114 is positioned on the distal side of permanent magnet 112 (i.e., farther from interface surface 107 than permanent magnet 112) and spaced apart from permanent magnet 112, creating a gap 115 along the z-axis. Pole pieces 116 are disposed at the longitudinal ends of permanent magnet 112 and switchable magnet 114 and span gap 115.
Permanent magnet 112 can be made of a magnetic material (i.e., a material that can be magnetized in a particular direction and sustain magnetization). In some embodiments, permanent magnet 112 is made of a material with high magnetic coercivity. For example, permanent magnet 112 can be a rare earth magnet such as a neodymium-iron-boron (NdFeB) magnet or the like. Permanent magnet 112 is magnetized, with magnetic polarity 113 (shown using arrows) fixedly oriented along a longitudinal direction (the +x direction in this example).
Switchable magnet 114 can have a core 108 made of a magnetic material. In some embodiments, core 108 can be made of a permanent (or hard) magnetic material with low magnetic coercivity. For example, core 108 can be made of an aluminum-nickel-cobalt material (AlNiCo) or the like. “High” and “low” are relative terms, and in this context signify that the coercivity of permanent magnet 112 can be higher than the coercivity of core 108; the relationship is described further below.
A conductive coil 118 (e.g., copper wire) is wrapped around core 108, e.g., such that the axis of the coil aligns with the easy axis of the magnetic material within core 108. In operation, the direction of magnetic polarization of core 108 (and therefore of switchable magnet 114) can be changed by driving a current pulse through coil 118 in one direction or the other. In
Pole pieces 116 can be made of a soft magnetic material that acts as a magnetic shunt, such as steel, iron-cobalt (FeCo), or other material. Suitable materials are easily magnetized or demagnetized and can lose their magnetization when external magnetic fields are absent. Pole pieces 116 can be oriented to direct flux along the z-axis (toward or away from interface surface 107). For instance, many magnetic materials have a particular axis (sometimes referred to as an “easy axis”) along which they can be easily magnetized in either direction, and pole pieces 116 can have their easy axes oriented parallel to the z-axis.
Fixed magnetic element 120 includes permanent magnets 122a, 122b and a support plate 124. Permanent magnets 122a, 122b can be made of a permanent magnetic material. In some embodiments, permanent magnets 122a, 122b are made of a material with high magnetic coercivity. Permanent magnets 122a, 122b can be but need not be made of the same material as permanent magnet 112. Permanent magnets 122a, 122b are magnetized, with magnetic polarity fixedly oriented along a direction transverse to (e.g., normal to) interface surface 107, as shown by arrows 123a. 123b. It should be noted that magnets 122a, 122b have magnetic polarity in opposite directions from each other; in this example, arrow 123a points down while arrow 123b points up. Support plate 124 can be made of a soft magnetic material that acts as a magnetic shunt to direct flux longitudinally, such as steel, iron-cobalt (FeCo), or other material.
In operation, by driving current pulses in coil 118 in different directions, EPM 110 can be switched between an “ON” state in which a magnetic force is created between EPM 110 and fixed magnetic element 120 and an “OFF” state in which negligible magnetic force is created between EPM 110 and fixed magnetic element 120.
The particular dimensions, materials, and form factor of EPM 110 and fixed magnetic element 120 can be chosen as desired for a particular application, subject to various design considerations. For example, it is desirable that coil 118 can be used to flip the magnetic polarization of core 108 without affecting magnetic polarization of permanent magnet 112. In some embodiments, this can be achieved in part by making permanent magnet 112 and core 108 out of different magnetic materials such that permanent magnet 112 has higher coercivity than core 108. For instance, permanent magnet 112 can be a NdFeB magnet while core 108 is an AlNiCo magnet. In some embodiments, coercivity of permanent magnet 112 can be higher than coercivity of core 108 by a factor of 5 or 10; however, use of different magnetic materials is not required, and in some embodiments permanent magnet 112 and core 108 can be made of the same or similar materials. Given a particular combination of permanent magnet 112 and core 108, gap 115 can be made large enough (in the direction along the z-axis) that a current pulse of sufficient intensity (e.g., peak current) to flip the magnetic polarization of core 108 can be propagated through coil 118 without affecting permanent magnet 112. Further, it is also desirable that core 108 retain the magnetization imparted by a current pulse in coil 118, which may be opposite the magnetization of permanent magnet 112. To prevent permanent magnet 112 from affecting magnetic orientation of core 108 (or vice versa), gap 115 can have a height sufficient that magnetic reluctance prevents permanent magnet 112 from affecting core 108. These considerations set a minimum height for gap 115, with the particular value depending on the choice of magnetic materials and dimensions of the magnets. The height of gap 15 can be greater than the minimum if a larger form factor can be tolerated in a particular application.
Dimensions of permanent magnet 112, switchable magnet 114, and pole pieces 116 can be chosen to balance the flux and reduce flux leakage in the OFF state. In some embodiments, this may result in core 108 being significantly taller (along the z-direction) than permanent magnet 112.
Dimensions of permanent magnets 122a, 122b can be chosen as desired. In some embodiments, permanent magnets 122a, 122b can be as wide (along the x-direction) as EPM 110, with magnets 122a, 122b being offset such that each magnet 122a, 122b is centered over one or the other of pole pieces 116. If desired, a space can be provided between permanent magnets 122a, 122b. Balancing of flux between EPM 110 in the ON state and fixed magnetic element 120 is not required.
In some embodiments, the alignment of EPM 110 and permanent magnets 122 in fixed magnetic element 120 can be modified so that the ON state of EPM 110 provides magnetic repulsion rather than attraction.
Accordingly, different of magnetic elements can provide either attraction or repulsion when EPM 110 is in the ON state. Assuming the magnets in fixed magnetic element 120 have fixed polarization and are at fixed positions along the longitudinal direction, whether the ON state of EPM 110 produces attractive or repulsive force on fixed magnetic element 120 depends on the alignment of magnets 122a, 122b relative to permanent magnet 112.
In some embodiments, a magnetic system can include arrays of magnetic elements of the kind shown in
As described above with reference to
Fixed magnet array 260 can include an array of fixed magnetic elements 220, each of which can be an instance of fixed magnetic element 120 of
When EPMs 210 are in the ON state, flux circulates in loops shown by large dashed arrows 235. It should also be noted that flux loops produced by adjacent EPMs 210 circulate in opposite directions (as shown) so that contributions to flux through a given pole piece 216 from the switchable magnet element at either side align in the same direction, which can increase the force on fixed magnet array 260. In this example, fixed magnetic element 220 is arranged such that the magnetic flux creates an attractive force when EPMs 210 are in the ON state. As shown by arrows 236, flux in pole pieces 216 flows upward where permanent magnets 222b are located and downward where permanent magnets 222a are located, resulting in an attractive force.
In some embodiments, a magnetic system that provides repulsive magnetic force can be created by reversing the polarity of the fixed magnets (e.g., as illustrated in
Compared to magnetic system 200 of
It may be desirable for a magnetic system to provide attraction and repulsion at different times. For example, when a user closes the lid of a laptop, it may be desirable for the lid to be drawn closed and/or held closed using magnetic attraction. When a user begins to open the lid, it may be desirable to provide magnetic repulsion to facilitate the opening action. Accordingly, some embodiments provide dual-action magnetic systems that can be operated to selectively provide attraction, repulsion, or a “neutral” (or “off”) state of low magnetic force. For example, one section of a magnet array can be configured for attraction (e.g., as in
A controllable magnet array 550 can be attached to or housed within base 502, oriented toward interface surface 503 of lid 504. A fixed magnet array 560 can be attached to or housed within lid 504, oriented toward interface surface 505 of base 502. Controllable magnet array 550 and fixed magnet array 560 can be oriented such that they come into proximity with each other as lid 504 moves toward the closed position. Direct contact between controllable magnet array 550 and fixed magnet array 560 when in the closed position is not required; however, smaller gaps between controllable magnet array 550 and fixed magnet array 560 correspond to increased magnetic strength (if all other factors are equal). Any intervening surfaces (e.g., a housing of base 502 or lid 504) should have low magnetic permeability so that flux can pass through. For instance, a plastic cover may be disposed over either or both of controllable magnet array 550 and fixed magnet array 560 to protect and/or conceal the magnets.
In some embodiments, controllable magnet array 550 includes two independently operable sections: section 511 and section 513. Each section 511, 513 can include an array of EPMs 510, 512 which can be similar or identical to EPMs 110 (
In operation, when lid 504 is open (e.g., during normal laptop use), sections 511 and 513 of controllable magnet array 550 can both be in the OFF state, which (as described above) reduces stray magnetic flux in the vicinity of controllable magnet array 550. When lid 504 is moved into or toward the closed position, section 511 of controllable magnet array 550 can be switched to the ON state (while section 513 remains in the OFF state), thereby providing attractive magnetic force toward section 521 of fixed magnet array 560. The attractive magnetic force may help draw lid 504 into the closed position and/or secure lid 504 in the closed position (e.g., by leaving section 511 in the ON state). It should be noted that power is consumed only when switching section 511 (or section 513) between states, and leaving section 511 in the ON state does not consume power.
When the user initiates opening of lid 504 from the closed position (e.g., by touching a sensor on the edge of the lid or exerting upward force or the like), section 511 of controllable magnet array 550 can be switched to the OFF state to release the attractive force toward section 521 of fixed magnet array 560. In addition, section 513 of controllable magnet array 550 can be switched to the ON state to create a repulsive force toward section 523 of fixed magnet array 560. This repulsive force can assist the user in lifting lid 504 or can cause lid 504 to pop open, creating a gap between lid 504 and base 502 that may facilitate further movement of lid 504 into a desired position for operating device 500.
In the example of
In some embodiments, the coil in each EPM (e.g., EPM 210 of
Control and driver circuit 600 can also include a controller 630, which can be implemented using a programmable microcontroller, FPGA, ASIC or the like. Controller 630 can have an input path 632 coupled to receive event signals. Event signals can indicate, for instance, that the controllable magnet array or sections thereof should be switched to the other state (e.g., from ON to OFF or vice versa). Responsive to the event signals, controller 630 can output voltages V1A, V1B, V1C, V1D to the gates of transistors 622, 624, 626, 628 to drive current (or not) in coil 618-1, and similarly for each other coil 618. In this example, controller 630 can drive the gate voltage of each transistor separately. Patterns or sequences of changes to voltages output by controller 630 can be defined to optimize state transitions in a magnet array (or a section thereof). For example, each coil in a magnet array (or a section thereof) can receive a current pulse in turn. Sequential pulsing of the coils may reduce peak power consumption as compared to parallel pulsing of all coils. As another example, in an array that has attractive and repulsive sections (e.g., controllable magnet array 550 of
Using control and driver circuit 600, the total time to effect a transition of the EPMs in a controllable magnet array between ON and OFF states after receiving an event signal depends on various considerations, including the number of coils (assuming one coil is pulsed at a time), the duration of a current pulse and the time between current pulses. In some embodiments for an array with four switchable elements in an attractive section and four switchable elements in a repulsive section, the total time can be a millisecond or less, short enough that a user would not perceive the response as delayed.
Further illustrating operation of controller 630,
At block 702, controller 630 can receive an event signal (e.g., via input path 632) indicating that lid 504 is being closed. Depending on implementation and the particulars of device 500, a “Close” event signal can be generated under various conditions. For example, a force or acceleration sensor in lid 504 can detect movement toward the closed position, or the user may operate a control (e.g., press a button, touch a particular surface, or issue a voice command) to indicate that lid 504 should be closed or that the magnetic latch should be engaged. In some embodiments, a “Close” event signal may be generated during initial power-up of device 500 to initialize the magnetic system into a known state.
At block 704, controller 630 can pulse current through each coil in repulsion section 513 of controllable magnet array 550 to drive EPMs 512 to the OFF state. For instance, controller 630 can deliver a current pulse through a given coil by applying appropriate voltages on the gates of the transistors coupled to that coil, as described above. In some embodiments, the voltages can be controlled so that one coil at a time receives a current pulse. The result of block 704 can be that repulsion section 513 exerts little or no force on repulsion section 523. At block 706, controller 630 can pulse current through each coil in attraction section 511 of controllable magnet array 550 to drive EPMs 510 to the ON state. For instance, controller 630 can deliver a current pulse through a given coil by applying appropriate voltages to the gates of the transistors coupled to that coil, as described above. In some embodiments, the voltages can be controlled so that one coil at a time receives a current pulse. The result of block 706 can be that attraction section 511 exerts attractive force on attraction section 521. Thus, lid 504 can be drawn toward or held in a closed position adjacent to (e.g., such that at least a portion of lid 504 abuts) base 502.
At block 802, controller 630 can receive a “Release” event signal (e.g., via input path 632) indicating that the magnetic latch should be released Depending on implementation and the particulars of device 500, a “Release” event signal can be generated under various conditions.
For example, a force or acceleration sensor in lid 504 can detect movement away from the closed position, or the user may operate a control (e.g., press a button, touch a particular surface, or issue a voice command) to indicate that lid 504 should be opened or that the magnetic latch should be released (or disengaged). In some embodiments, the state machine in the component that generates event signals can be designed such that a “Release” event signal is generated only if the preceding event signal was a “Close” signal.
At block 804, controller 630 can pulse current through each coil in attraction section 511 of controllable magnet array 550 to drive EPMs 510 to the OFF state. For instance, controller 630 can deliver a current pulse through a given coil by applying appropriate voltages on the gates of the transistors coupled to that coil, as described above. In some embodiments, the voltages can be controlled so that one coil at a time receives a current pulse. The result of block 804 can be that attraction section 511 ceases to exert a significant attractive force on attraction section 521. At block 806, controller 630 can pulse current through each coil in repulsion section 513 of controllable magnet array 550 to drive EPMs 512 to the ON state. For instance, controller 630 can deliver a current pulse through a given coil by applying appropriate voltages on the gates of the transistors coupled to that coil, as described above. In some embodiments, the voltages can be controlled so that one coil at a time receives a current pulse. The result of block 806 can be that repulsion section 513 exerts repulsive force on repulsion section 523. Thus, lid 504 can be pushed away from base 502, creating a gap between the two. From there, the user (or an electrical or mechanical element that applies additional force) can further open lid 504.
In some embodiments, it may not be desirable to leave the switchable magnet elements of repulsion section 513 in the ON state while lid 504 is open. For instance, switchable magnetic elements of repulsion section 513 may generate enough external flux in the ON state to interfere with or affect nearby devices or objects (e.g., credit cards) while lid 504 is open. Accordingly, at block 808, controller 630 can receive an “Opened” event signal, indicating that lid 504 has been opened to a sufficient degree that repulsion section 513 is no longer contributing to further opening of lid 504. In response to the “Opened” event signal, controller 630 can pulse current through each coil in repulsion section 513 of controllable magnet array 550 to drive EPMs 512 to the OFF state.
In various embodiments, other events can be used to trigger switching of EPMs 512 to the OFF state, in addition to or instead of the “Opened” event signal at block 808. For example, a timer can be used. The timer can start, e.g., when controller 630 completes block 806 of process 800 and can expire after a prescribed time (e.g., five seconds, twenty seconds, or the like), after which controller 630 proceeds to block 808.
It should be understood that processes 700 and 800 are illustrative and that variations and modifications are possible. In some embodiments, controller 630 can sequence the gate voltages delivered to driver section 602 such that a current pulse is supplied to only coil at a time. In process 700, all EPMs 512 in repulsion section 513 can be switched to the OFF state prior to switching any of the EPMs 510 in attraction section 511 to the ON state, and in process 800, all EPMs 510 in attraction section 511 can be switched to the OFF state prior to switching any of the EPMs 512 in repulsion section 513 to the ON state. In this manner, the magnetic system as a whole can transition smoothly from repulsion through neutral to attraction and in the reverse direction.
Alternatively, if desired, controller 630 can use a different sequence (e.g., alternating between switching a magnetic element in repulsion section 513 to the OFF state and switching a magnetic element in attraction section 511 to the ON state).
In processes 700 and 800, controller 630 does not need to determine the state of any EPM prior to applying the current pulse; circuit 600 can be designed to deliver a current pulse of sufficient magnitude to switch the magnetic polarization of the EPM to the desired orientation without regard to the orientation direction prior to the pulse. If a particular EPM is already in the desired orientation, the current pulse will have no effect. If desired, controller 630 can track current state of a given EPM and adjust the current pulse accordingly; however, additional power may be required to maintain and/or update stored state information, and net power savings may be negligible or nonexistent.
The particular event signals and order thereof are also illustrative Any number and combination of event signals can be defined, and controller 630 can be configured (e.g., using programming or logic circuitry) to generate appropriate current pulses for the state transition associated with a particular event. The conditions that trigger sending of event signals to controller 630 can be defined in any manner desired without departing from the scope of this disclosure.
In some embodiments, it may not be desirable to leave the magnetic latch disengaged for a prolonged period in the absence of user activity. For example, after executing block 806 of process 800, controller 630 may wait for the “Opened” event signal at block 808 for a prescribed timeout period (e.g., ten seconds, thirty seconds, two minutes). If no “Opened” event signal is received within the timeout period, controller 630 can re-engage the magnetic latch, e.g., by executing blocks 704 and 706 of process 700. Other combinations and sequences of events can also be supported.
Other variations are also possible. For example, it may be desirable to exert different amounts of attractive or repulsive force at different times. In some embodiments, this can be achieved by switching some but not all switchable magnetic elements in one section or the other to the ON state while switching other switchable magnetic elements in the same section to the OFF state. For example, referring to
If desired, controller 630 can include an output signal path that can return information about the current state of the magnetic system to other system components. For instance, controller 630 can send output signals indicating the ON or OFF state of switchable magnetic elements based on the most recently delivered current pulse to each element. Such information can be used, e.g., to activate or deactivate indicator lights, to generate notification messages, to enable various security features, or the like.
In embodiments such as device 500 described above, a dual-action magnetic system includes different sections, with one pair of sections (e.g., sections 511 and 521) providing a switchable attractive magnetic force and another pair of sections (e.g., sections 513 and 523) providing a switchable repulsive magnetic force. In some alternative embodiments, switchable magnetic elements can be used to provide both attractive and repulsive forces on the same fixed magnet array (at different times).
Controllable magnet array 950 can include an array of EPMs 910 arranged end-to-end. In this example, each EPM 910 includes two switchable magnets 914, 918. Each switchable magnet 914, 918 can be implemented similarly to switchable magnet 114 of
In this configuration, each EPM 910 has a first ON state in which both of switchable magnets 914 and 918 have magnetic polarity oriented in the +x direction, a second ON state in which both of switchable magnets 914 and 918 both have magnetic polarity oriented in the −x direction, and an OFF state in which switchable magnets 914 and 918 have magnetic polarity oriented in antiparallel directions. Current pulses can be applied to one or both of switchable magnets 914 and 918 to switch among the three states.
By switching the states of EPMs 910 among the three states, it is possible to obtain both attraction and repulsion at different times. For instance in a first configuration where adjacent EPMs 910 are in ON states oriented in opposite directions, magnetic flux as shown in
While the invention has been described with reference to specific embodiments, those skilled in the art will appreciate that variations and modifications are possible. For instance, the size of the magnetic elements and number of EPMs in the controllable magnet arrays can be varied, and the size and number of permanent magnets in the fixed magnet arrays can be correspondingly varied. In some embodiments, multiple controllable magnet arrays can be provided in a magnetic system, and operation of the controllable magnet arrays can be coordinated using a shared controller. All materials described herein are illustrative, and other materials with appropriate magnetic properties (as described above) can be substituted. In some embodiments, controllable magnet arrays of the kind described herein can be used with an appropriately shaped magnetic shunt (e.g., a piece of soft magnetic material such as steel) in place of the fixed magnet array; those skilled in the art will appreciate that where a magnetic shunt is used in place of the fixed magnet array, only attractive magnetic force would be created.
In examples described above, controllable magnet arrays and corresponding fixed magnet arrays have the magnets arranged in a straight line. Straight lines are used for clarity of illustration, and other embodiments can include magnet arrays having curved sections and/or corners. For example, pole pieces in a controllable magnet array using EPMs can be shaped to provide curvature or corners, and the magnets in the corresponding fixed magnet array can be arranged to correspond to the locations of the pole pieces.
Magnetic systems of the kind described herein can be applied in any context where the ability to selectively apply attractive and/or repulsive force between a first object or surface and a second object or surface is desirable. An example of opening and closing a lid of a laptop is described above; however, many other applications are possible. Other example applications include opening and closing a door, operating a mechanical switch or relay, removably attaching one object to another (e.g., a portable device that can be held on a stand), and so on.
All processes described herein are also illustrative and can be modified. Operations can be performed in a different order from that described, to the extent that logic permits; operations described above may be omitted or combined; and operations not expressly described above may be added.
While various circuits and components are described herein with reference to particular blocks, it is to be understood that these blocks are defined for convenience of description and are not intended to imply a particular physical arrangement of component parts. The blocks need not correspond to physically distinct components, and the same physical components can be used to implement aspects of multiple blocks. Components described as dedicated or fixed-function circuits can be configured to perform operations by providing a suitable arrangement of circuit components (e.g., logic gates, registers, switches, etc.); automated design tools can be used to generate appropriate arrangements of circuit components implementing operations described herein. Components described as processors or microprocessors can be configured to perform operations described herein by providing suitable program code. Various blocks might or might not be reconfigurable depending on how the initial configuration is obtained. Embodiments of the present invention can be realized in a variety of apparatus including electronic devices implemented using a combination of circuitry and software.
It should be understood that directional terms such as “up,” “down,” “above,” “below,” and the like are used herein for simplicity of description. Such terms should be understood as distinguishing different direction in a coordinate system that can have any orientation in space.
All numerical values and ranges provided herein are illustrative and may be modified. Unless otherwise indicated, drawings should be understood as schematic and not to scale.
Accordingly, although the invention has been described with respect to specific embodiments, it will be appreciated that the invention is intended to cover all modifications and equivalents within the scope of the following claims.
This application claims the benefit of U.S. Provisional Application No. 63/541,259, filed Sep. 28, 2023.
| Number | Date | Country | |
|---|---|---|---|
| 63541259 | Sep 2023 | US |
