Magnetic system incorporating array of electro-permanent magnets

Abstract

The invention relates to a magnetic system incorporating an array of electro-permanent magnets. The invention discloses a magnetic system. The magnetic system can comprise a controllable magnet array and a fixed magnet array. The fixed magnetic array may include an array of permanent magnets having alternating polarization directions transverse to the array. Some controllable magnet arrays may include electro-permanent magnets (EPMs) arranged end-to-end with pole pieces located between the electro-permanent magnets aligned with the permanent magnets of the fixed magnet array. Each EPM may include permanent magnets having a fixed magnetic orientation transverse to the array and antiparallel to permanent magnets in an adjacent EPM; and a switchable magnet, the magnetic orientation of which is switchable between parallel and anti-parallel with the permanent magnets in the EPM.

Description

Technical Field

[0001] The present disclosure relates to magnetic systems, and more particularly to magnetic systems switchable between an attractive state and a repulsive state. Background Art

[0002] Magnetic latches can be used to hold two parts in a closed position, with opposing surfaces abutting or contacting each other. For example, permanent magnets can be included in the base and lid of a laptop computer. When the lid approaches 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 a user pushing on the lid to open it, while making it less likely that the lid will simply open accidentally, for example, when transporting the laptop. In addition, magnetic latches, lacking moving parts, can be more durable than mechanical latches.

[0003] However, permanent magnets may generate external magnetic fields even when the laptop is open. Thus, for example, a permanent magnet in the base that is strong enough to effectively latch the lid when it is open may generate a field strong enough to affect or damage other nearby devices or items (such as credit cards). Summary of the invention

[0004] Certain embodiments described herein relate to magnetic systems that can switch from attractive magnetic forces to repulsive magnetic forces between components of the system. In some embodiments, the system may also have a neutral state in which little or no magnetic force is generated. The magnetic system may include a "fixed" magnet array, which includes permanent magnets with fixed magnetic polarization; and a "switchable" magnet array, which includes magnetic elements whose magnetic polarization direction can be switched to either of two opposite directions, such as electropermanent magnets. The permanent magnets and switchable magnetic elements may be arranged in their respective arrays so that, depending on the state of the switchable magnetic elements, an attractive magnetic force or a repulsive magnetic force (or in some cases, a negligible magnetic force) is generated between the fixed magnet array and the controllable magnet array.

[0005] Certain embodiments described herein relate to magnetic systems incorporating an electropermanent magnet (EPM) as a switchable magnetic element. The EPM provides a magnetic field that can be turned on or off using a current pulse. A current pulse in one direction turns the EPM on; a pulse in the other direction turns the EPM off. The EPM can maintain its magnetization state (on or off) after the current pulse ends. Therefore, power is only required when the magnetization state changes.

[0006] According to some embodiments, the magnetic system may include an electropermanent array and a fixed magnet array. The controllable magnet array may include two or more electropermanent magnets placed end to end. Each electropermanent magnet may include: a first permanent magnet, which is arranged close to the interface surface and has a fixed magnetic orientation along the longitudinal axis; a switchable magnet, which includes a core made of a magnetic material and a coil wound around the core along the longitudinal axis of the core, wherein the switchable magnet is positioned on the far side of the first permanent magnet and is spaced apart from the first permanent magnet; and a pole piece, which is arranged at each longitudinal end of the first permanent magnet and the switchable magnet, wherein the pole pieces are made of soft magnetic material and extend across the end surfaces of the first permanent magnet and the electropermanent magnet. The fixed magnetic orientations of the first permanent magnets in adjacent electropermanent magnets may be antiparallel to each other, and the pole pieces may be shared between adjacent electropermanent magnets in the controllable magnet array. The fixed magnet array may include second permanent magnets that are arranged parallel to the interface surface so that each second permanent magnet is aligned with one of the pole pieces of the controllable magnet array. Adjacent second permanent magnets may have fixed magnetic polarizations in opposite directions toward or away from the interface surface. The control and drive circuit may be coupled to each of the coils and configured to supply current pulses to the coils to switch the magnetic polarization direction of the core of the electropermanent magnet, thereby switching the electropermanent magnet between an on state and an off state, in which the magnetic polarization direction of the core is parallel to the magnetic polarization of the first permanent magnet, and in which the magnetic polarization direction of the core is antiparallel to the magnetic polarization of the first permanent magnet. The control and drive circuit may be configured to supply current pulses to different coils at different times.

[0007] If the second permanent magnet is aligned relative to the first permanent magnet so that the magnetization direction is parallel to the direction of flux passing through the pole piece when the electropermanent magnet is in the on state, an attractive magnetic force between the fixed magnet array and the controllable magnet array can be generated by switching the electropermanent magnet to the on state. However, if the second permanent magnet is aligned relative to the first permanent magnet so that the magnetization direction is antiparallel to the direction of flux passing through the pole piece when the electropermanent magnet is in the on state, a repulsive magnetic force between the fixed magnet array and the controllable magnet array can be generated by switching the electropermanent magnet to the on state. In some embodiments, the magnetic system may include a first portion and a second portion, in which the second permanent magnet is aligned relative to the first permanent magnet so as to provide an attractive magnetic force, and in which the second permanent magnet is aligned relative to the first permanent magnet so as to provide a repulsive magnetic force. By selectively turning different EPMs on and off, the magnetic system can provide an attractive force, a repulsive force, or a neutral state (e.g., all EPMs are in the off state) at different times.

[0008] This type of magnetic system can be deployed to selectively generate attractive magnetic forces 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 computer 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 generated at different times. For example, an attractive force can be generated to help close the lid or secure the lid in a closed position, and / or a repulsive force can be generated to cause the lid to pop open (or slightly open) from a closed position. The EPM array can also be turned off when magnetic forces are not needed (e.g., when the laptop is opened for use), thereby reducing stray magnetic fields.

[0009] According to some embodiments, the magnetic system may include an electropermanent array and a fixed magnet array. The controllable magnet array may include two or more electropermanent magnets placed end to end. Each electropermanent magnet may include a first switchable magnet and a second switchable magnet, the first switchable magnet being arranged close to the interface surface and being made of a first core made of a magnetic material and a first coil wound around the first core along the longitudinal axis of the first core, the second switchable magnet having a second core made of a magnetic material and a second coil wound around the second core along the longitudinal axis of the second core, wherein the second switchable magnet is positioned on the far side of the first switchable magnet and is spaced apart from the first switchable magnet. Pole pieces may be arranged at each longitudinal end of the first switchable magnet and the second switchable magnet, wherein these pole pieces are made of a soft magnetic material and extend across the end surfaces of the first switchable magnet and the second switchable magnet. Pole pieces may be shared between adjacent electropermanent magnets in the controllable magnet array. The fixed magnet array may include permanent magnets arranged parallel to the interface surface so that each permanent magnet is aligned with one of the pole pieces of the controllable magnet array. Adjacent permanent magnets may have magnetic polarizations in opposite directions toward or away from the interface surface. The control and drive circuit is coupled to each of the first coil and the second coil, and is configured to supply current pulses to the first coil and the second coil, thereby switching the electro-permanent magnet between a first on state, a second on state, and a closed state, in which the magnetic polarizations of the first switchable magnet and the second switchable magnet are parallel and in a first longitudinal direction, in the second on state, the magnetic polarizations of the first switchable magnet and the second switchable magnet are parallel and in a second longitudinal direction opposite to the first longitudinal direction, and in the closed state, the magnetic polarizations of the first switchable magnet and the second switchable magnet are in anti-parallel longitudinal directions. The control and drive circuit may be configured to supply current pulses to different coils at different times.

[0010] The following detailed description together with the accompanying drawings will provide a better understanding of the nature and advantages of the present invention as protected by the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figures 1A to 1C Shown is a simplified side view of elements of a magnetic system according to some embodiments.

[0012] Figure 2 A simplified perspective view of a magnetic system is shown according to some embodiments.

[0013] Figure 3A and Figure 3B is a two-dimensional plot illustrating magnetic flux in a magnetic system according to some embodiments.

[0014] Figure 4 A simplified perspective view of a magnetic system is shown according to some embodiments.

[0015] Figure 5 Shown is a simplified side view of a device incorporating a dual-acting magnetic system according to some embodiments.

[0016] Figure 6 A simplified schematic diagram of control and drive circuitry for a magnetic system is shown according to some embodiments.

[0017] Figure 7 and Figure 8 A flow chart showing a process that may be implemented in control and drive circuits according to some embodiments is shown.

[0018] Fig. 9 A simplified perspective view of a dual-acting magnetic system is shown in accordance with some embodiments. DETAILED DESCRIPTION

[0019] The following description of exemplary embodiments of the present invention is provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the claimed invention to the precise form described, and those skilled in the art will appreciate that many modifications and variations are possible. The embodiments have been selected and described to fully illustrate the principles of the invention and its practical application, thereby enabling others skilled in the art to fully utilize the invention in various embodiments and with various modifications suitable for the particular use contemplated.

[0020] Certain embodiments described herein relate to magnetic systems that can switch from attractive magnetic forces to repulsive magnetic forces between components of the system. In some embodiments, the system may also have a neutral state in which little or no magnetic force is generated. The magnetic system may include a "fixed" magnet array, which includes permanent magnets with fixed magnetic polarization; and a "switchable" magnet array, which includes electropermanent magnetic elements whose magnetic polarization direction can be switched to either of two opposite directions. The permanent magnets and the switchable magnetic elements may be arranged in their respective arrays so that, depending on the state of the switchable magnetic elements, an attractive magnetic force or a repulsive magnetic force (or a negligible magnetic force in some embodiments) is generated between the fixed magnet array and the controllable magnet array.

[0021] Certain embodiments described herein relate to magnetic systems incorporating an electropermanent magnet (EPM) as a switchable magnetic element. The EPM provides a magnetic field that can be turned on or off using a current pulse. A current pulse in one direction turns the EPM on; a pulse in the other direction turns the EPM off. The EPM can maintain its magnetization state (on or off) after the current pulse ends. Therefore, power is only required when the magnetization state changes.

[0022] Figure 1A and Figure 1B A simplified side view of the elements of a magnetic system according to some embodiments is shown. An electropermanent magnet (EPM) 110 and a fixed magnetic element 120 are shown. ("Fixed" is used herein to indicate that the magnetic polarization of the magnetic element does not change during device operation.) For ease of description, the magnetic polarization of the magnetic element 120 may be as shown in FIG. Figure 1A The x-axis is sometimes referred to herein as the "longitudinal" dimension or direction, and the z-axis is sometimes referred to as the "lateral" or "vertical", where "up" corresponds to the +z direction, etc. It should be understood that all directional terms are used for ease of description and do not require a particular orientation in space.

[0023] More specifically, the EPM 110 includes a permanent magnet 112, a switchable magnet 114, and a pole piece 116. The permanent magnet 112 may be positioned proximate to the interface surface 107 (as shown in dashed lines), while the switchable magnet 114 is positioned distal to the permanent magnet 112 (i.e., further away from the interface surface 107 than the permanent magnet 112) and spaced apart from the permanent magnet 112, thereby creating a gap 115 along the z-axis. The pole piece 116 is disposed at the longitudinal ends of the permanent magnet 112 and the switchable magnet 114, and spans the gap 115.

[0024] The permanent magnet 112 may be made of a magnetic material (i.e., a material that can be magnetized and maintain magnetization in a specific direction). In some embodiments, the permanent magnet 112 is made of a material having a high magnetic coercivity. For example, the permanent magnet 112 may be a rare earth magnet, such as a neodymium iron boron (NdFeB) magnet, etc. The permanent magnet 112 is magnetized with a magnetic polarity 113 (shown using arrows) fixedly oriented along the longitudinal direction (in this example, the +x direction).

[0025] The switchable magnet 114 may have a core 108 made of a magnetic material. In some embodiments, the core 108 may be made of a permanent (or hard) magnetic material with a low magnetic coercivity. For example, the core 108 may be made of an aluminum nickel cobalt material (AlNiCo), etc. "High" and "low" are relative terms, and in this context mean that the coercivity of the permanent magnet 112 may be higher than the coercivity of the core 108; this relationship is further described below.

[0026] A conductive coil 118 (e.g., copper wire) is wound around the core 108, for example so that the axis of the coil is aligned with the easy axis of magnetization of the magnetic material within the core 108. In operation, the direction of the magnetic polarization of the core 108 (and therefore the switchable magnet 114) can be changed by driving a current pulse through the coil 118 in one direction or the other. Figure 1A In FIG. 1 , the switchable magnet 114 has a magnetic polarity oriented in the +x direction, as indicated by arrow 117, and in Figure 1B , the switchable magnet 114 has a magnetic polarity oriented in the -x direction, as indicated by arrow 117'. Once polarized in a particular direction by a current pulse, the core 108 remains polarized. Therefore, when it is desired to change the polarization direction of the switchable magnet 114, it is only necessary to supply current to the coil 118.

[0027] The pole piece 116 may 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 may lose their magnetization when there is no external magnetic field. The pole piece 116 may be oriented to direct flux along the z-axis (toward or away from the interface surface 107). For example, many magnetic materials have a specific axis (sometimes called an "easy magnetization axis") along which they can be easily magnetized in either direction, and the pole piece 116 may have an easy magnetization axis oriented parallel to the z-axis.

[0028] The fixed magnetic element 120 includes permanent magnets 122a, 122b and a support plate 124. The permanent magnets 122a, 122b may be made of permanent magnetic materials. In some embodiments, the permanent magnets 122a, 122b are made of materials with high magnetic coercivity. The permanent magnets 122a, 122b may be, but need not be, made of the same material as the permanent magnet 112. The permanent magnets 122a, 122b are magnetized, and their magnetic polarity is fixedly oriented in a direction transverse to (e.g., perpendicular to) the interface surface 107, as shown by arrows 123a, 123b. It should be noted that the magnets 122a, 122b have magnetic polarities in opposite directions to each other; in this example, the arrow 123a points downward, while the arrow 123b points upward. The support plate 124 may be made of a soft magnetic material that acts as a magnetic shunt for longitudinally guiding flux, such as steel, iron cobalt (FeCo) or other materials.

[0029] 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 generated between EPM 110 and fixed magnetic element 120, and an “off” state, in which a negligible magnetic force is generated between EPM 110 and fixed magnetic element 120. Figure 1A The EPM 110 is shown in an open state. In the open state, the magnetic polarity 117 of the switchable magnet 114 has been switched (by a current pulse in the drive coil 118) to be parallel to the magnetic polarity 113 of the permanent magnet 112. In this state, magnetic flux indicated by the large dashed arrow 135 flows through the permanent magnet 112 and the switchable magnet 114 in the +x direction and circulates through the pole piece 116 that guides the flux vertically. As shown, the flux is directed upward toward the magnet 122b having an upwardly oriented magnetic polarity (as indicated by arrow 123b), is directed along the support plate 124, and is directed downward through the magnet 122a having a downwardly oriented magnetic polarity (as indicated by arrow 123b). The magnetic flux creates an attractive force between the EPM 110 and the fixed magnetic element 120. As described below, the attractive force can be used to keep two surfaces in contact, such as latching a laptop lid (or door) in a closed position.

[0030] Figure 1BThe EPM 110 is shown in a closed state. In the closed state, the magnetic polarity 117 of the switchable magnet 114 has been switched (by a current pulse in the drive coil 118) to be anti-parallel to the magnetic polarity 113 of the permanent magnet 112, as indicated by arrow 117. In this state, magnetic flux, indicated by the large dashed arrow 135, flows through the permanent magnet 112 in the +x direction and through the switchable magnet 114 in the opposite (-x) direction. The pole piece 116 provides a return flux path, and the magnetic flux can be mostly or completely confined within the EPM 110. Since little or no magnetic flux reaches the magnets 122a, 122b in the fixed magnetic element 120, little or no force is applied between the EPM 110 and the fixed magnetic element 120.

[0031] The specific dimensions, materials, and form factors of the EPM 110 and the fixed magnetic element 120 can be selected as required by the specific application and are subject to various design considerations. For example, it is desirable that the coil 118 can be used to flip the magnetic polarization of the core 108 without affecting the magnetic polarization of the permanent magnet 112. In some embodiments, this can be achieved in part by manufacturing the permanent magnet 112 and the core 108 from different magnetic materials such that the permanent magnet 112 has a higher coercivity than the core 108. For example, the permanent magnet 112 can be an NdFeB magnet and the core 108 is an AlNiCo magnet. In some embodiments, the coercivity of the permanent magnet 112 can be 5 times or 10 times the coercivity of the core 108; however, it is not necessary to use different magnetic materials, and in some embodiments, the permanent magnet 112 and the 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) so that a current pulse (e.g., a peak current) strong enough to flip the magnetic polarization of core 108 can propagate through coil 118 without affecting permanent magnet 112. In addition, it is also desirable that core 108 maintains the magnetization imparted by the current pulse in coil 118, which can be opposite to the magnetization of permanent magnet 112. In order to prevent permanent magnet 112 from affecting the magnetic orientation of core 108 (or vice versa), gap 115 can have a sufficient height so that magnetic resistance prevents permanent magnet 112 from affecting core 108. These considerations set a minimum height for gap 115, the specific value of which depends on the choice of magnetic material and size of the magnet. If a larger form factor can be tolerated in a particular application, the height of gap 115 can be greater than the minimum value.

[0032] The dimensions of the permanent magnets 112 , switchable magnets 114 , and pole pieces 116 may be selected to balance flux and reduce flux leakage in the off state. In some embodiments, this may result in the core 108 being significantly taller than the permanent magnets 112 (along the z-direction).

[0033] The size of the permanent magnets 122a, 122b can be selected as desired. In some embodiments, the permanent magnets 122a, 122b can be as wide as the EPM 110 (along the x-direction), with the magnets 122a, 122b offset so that each magnet 122a, 122b is centered over one or the other of the pole pieces 116. Space can be provided between the permanent magnets 122a, 122b if desired. Flux balancing between the EPM 110 and the fixed magnetic element 120 in the on state is not required.

[0034] In some embodiments, the alignment of the permanent magnets 122 in the EPM 110 and the fixed magnetic element 120 may be modified so that the on state of the EPM 110 provides magnetic repulsion rather than attraction. Figure 1C A simplified side view of an arrangement of magnetic elements that can provide a repulsive force according to some embodiments is shown. EPM 110 and fixed magnetic element 120' are shown. EPM 110 can be used with Figure 1A and Figure 1B 1. The fixed magnetic element 120′ may be similar to the fixed magnetic element 120 described above and may include permanent magnets 122a′, 122b′ and a support plate 124. The permanent magnet 122a′ has a magnetic polarity in the -z direction (as indicated by arrow 123a′), while the magnet 122b′ has a magnetic polarity in the +z direction (as indicated by arrow 123b′). The alignment between the permanent magnets 122a′, 122b′ and the permanent magnet 112 of the EPM 110 is similar to the fixed magnetic element 120 described above and may include permanent magnets 122a′, 122b′ and a support plate 124. The permanent magnet 122a′ has a magnetic polarity in the -z direction (as indicated by arrow 123a′), while the magnet 122b′ has a magnetic polarity in the +z direction (as indicated by arrow 123b′). Figure 1A The alignment in is different. Figure 1A In the embodiment, when EPM 110 is in the on state, magnetic polarities 123a and 123b generate an attractive force. Figure 1C It is shown that when the EPM 110 is in the on state, the magnetic polarities 123a', 122b' create a repulsive force between the EPM 110 and the fixed magnetic element 120'.

[0035] Therefore, when the EPM 110 is in the on state, different magnetic elements can provide attraction or repulsion. Assuming that the magnets in the fixed magnetic element 120 have a fixed polarization and are in a fixed position along the longitudinal direction, whether the on state of the EPM 110 generates an attractive force or a repulsive force on the fixed magnetic element 120 depends on the alignment of the magnets 122a, 122b relative to the permanent magnet 112.

[0036] In some embodiments, the magnetic system may include Figures 1A to 1C An array of magnetic elements of the type shown. Figure 22 shows a simplified perspective view of a magnetic system 200 according to some embodiments. The magnetic system 200 includes a controllable magnet array 250 and a fixed magnet array 260. The controllable magnet array 250 may include an array of EPMs 210, each of which may be an instance of an EPM 110 arranged end to end. For example, each EPM 210 may include a permanent magnet 212 (corresponding to Figure 1A and Figure 1B The permanent magnet 112 in the embodiment of the present invention), the switchable magnet 214 (corresponding to Figure 1A and Figure 1B ), and pole pieces 216 disposed at either end (corresponding to Figure 1A and Figure 1B 216). Pole pieces 216 may be shared between adjacent EPMs 210. The EPMs 210 are arranged so that the permanent magnets 212 in adjacent EPMs 210 have magnetic polarities in opposite directions, as indicated by green arrows 213. Each EPM 210 may be switched between an on state (as described above, by applying current pulses in different directions to the coils of the switchable magnets 214), in which the magnetic polarity of the switchable magnets 214 is parallel to the magnetic polarity of the corresponding permanent magnets 212 (i.e., the permanent magnets 212 in the same EPM 210), and an off state in which the magnetic polarity of the switchable magnets 214 is antiparallel to the magnetic polarity of the corresponding permanent magnets 212; switchability is indicated by double-headed red arrows 217. Each switchable magnet 214 may have its own coil, and the coils for different switchable magnets 214 may be pulsed independently. For example, as described below, different EPMs 210 may be switched from on to off, or vice versa, sequentially.

[0037] As mentioned above Figure 1A and Figure 1B As described, each EPM 210 has an on state and an off state, in which the magnetic polarity of the switchable magnet 214 is parallel to the magnetic polarity of the permanent magnet 212, and in which the magnetic polarity of the switchable magnet 214 is antiparallel to the magnetic polarity of the permanent magnet 212. A current pulse can be applied to switch between the two states.

[0038] Fixed magnet array 260 may include an array of fixed magnetic elements 220, each of which may be Figure 1A and Figure 1B For example, each fixed magnetic element 220 may include permanent magnets 222a, 222b (corresponding to the permanent magnets 222a, 222b) having magnetic polarities in opposite directions (as indicated by arrows 223a, 223b). Figure 1A and Figure 1B The permanent magnets 122a, 122b) and the support plate 224 (corresponding to Figure 1A and Figure 1B The permanent magnets 222a, 222b alternate polarity directions along the length of the fixed magnet array 260, and the same permanent magnet can be shared between adjacent fixed magnetic elements 220. For example, each permanent magnet 222a, 222b can be centered above one of the pole pieces 216.

[0039] When the EPM 210 is in the on state, the flux circulates in a loop as indicated by the large dashed arrow 235. It should also be noted that the flux loops generated by adjacent EPMs 210 circulate in opposite directions (as shown) so that the contributions from the switchable magnetic elements on both sides to the flux passing through a given pole piece 216 are aligned in the same direction, which can increase the force on the fixed magnet array 260. In this example, the fixed magnetic elements 220 are arranged so that when the EPM 210 is in the on state, the magnetic flux creates an attractive force. As shown by arrows 236, the flux in the pole piece 216 flows upward at the location of the permanent magnet 222b and flows downward at the location of the permanent magnet 222a, thereby creating an attractive force.

[0040] Figure 3A and Figure 3B is a two-dimensional plot illustrating magnetic flux in a magnetic system similar to system 200 according to some embodiments. For each point in space, the magnetic field strength is indicated using a color scale, and the direction is indicated using an arrow. Figure 3A 1 shows a plot when all switchable magnetic elements are in the on state. It can be seen that in a fixed magnet array (e.g., Figure 3A A strong field component in the z direction is generated in the permanent magnet of the region 322 in the controllable magnet array (e.g., Figure 3A The flux in the z direction in the magnetic pole piece of region 316 in the magnet is aligned. In this way, an attractive magnetic force can be generated. Figure 3B The corresponding plot is shown when the switchable magnetic elements are all in the off state.The magnetic field is significantly reduced in both regions 316 and 322, indicating little or no attractive force.

[0041] In some embodiments, a magnetic system that provides a repulsive magnetic force can be created by reversing the polarity of a stationary magnet (e.g., Figure 1C exemplified in ). Figure 4 A simplified perspective view of a magnetic system 400 according to some embodiments is shown. The magnetic system 400 includes a controllable magnet array 450 and a fixed magnet array 460. The controllable magnet array 450 may include an array of EPMs 410, each of which may be arranged end-to-end. Figure 1A and Figure 1C The EPM 410 may be arranged with fixed magnets 412 having alternating polarities, as described above with reference to Figure 2 The fixed magnet array 460 may include an array of fixed magnetic elements 420, each of which may be Figure 1C For example, each fixed magnetic element 420 may include permanent magnets 422a, 422b (corresponding to the magnetic polarity of the permanent magnets 422a, 422b) having magnetic polarity in opposite directions (as indicated by arrows 423a, 423b). Figure 1C The permanent magnets 122a', 122b') and the support plate 424 (corresponding to Figure 1A and 1B The permanent magnets 422a, 422b alternate polarity directions along the length of the fixed magnet array 460, and the same permanent magnet can be shared between adjacent fixed magnetic elements 420. For example, each permanent magnet 422a, 422b can be centered above one of the pole pieces 416.

[0042] and Figure 2 Compared to the magnetic system 200 of FIG. 1 , the alignment of permanent magnets 422a, 422b relative to permanent magnet 412 is opposite to the alignment of permanent magnets 222a, 222b relative to permanent magnet 212. As described above with reference to FIG. Figure 1C As described, this configuration generates a repelling magnetic force when EPM 410 is switched to the on state (and generates little or no magnetic force when EPM 410 is switched to the off state). The repelling force can be used, for example, to help a user open a closed laptop lid or to create separation between surfaces in other situations.

[0043] 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 computer, it may be desirable to use magnetic attraction to draw the lid closed and / or keep it closed. When the user begins to open the lid, it may be desirable to provide magnetic repulsion to facilitate the opening action. Therefore, some embodiments provide a dual-action magnetic system that is operable to selectively provide attraction, repulsion, or a "neutral" (or "off") state of low magnetic force. For example, a portion of a magnet array may be configured to attract (e.g., as shown in FIG. 2 ), while a portion of a magnet array may be configured to attract (e.g., as shown in FIG. 2 ). Figure 2 ), while the other part is configured for exclusion (for example, as in FIG. 3 ).

[0044] Figure 5A simplified side view of a device 500 incorporating a dual-acting magnetic system according to some embodiments is shown. The device 500 may be, for example, a laptop computer having a base 502 (which may include a keyboard, a touchpad, etc.) and a cover 504 (which may include a display, a camera, etc.). The base 502 and the cover 504 may be connected by a hinge 506, and the cover 504 may pivot between an open position and a closed position on the hinge 506. It should be understood that the device 500 may be any device that can be opened and closed, and the base 502 and the cover 504 may correspond to any two components having opposing surfaces that are brought together (entering a closed position in which at least a portion of the opposing surfaces are adjacent to each other) or separated (entering an open position). As used herein, the base 502 may be any structure incorporating a controllable magnet array of a magnetic system, and the cover 504 may be any structure incorporating a fixed magnet array.

[0045] The controllable magnet array 550 may be attached to or contained within the base 502, oriented toward the interface surface 503 of the cover 504. The fixed magnet array 560 may be attached to or contained within the cover 504, oriented toward the interface surface 505 of the base 502. The controllable magnet array 550 and the fixed magnet array 560 may be oriented so that they are close to each other when the cover 504 is moved toward the closed position. When in the closed position, direct contact between the controllable magnet array 550 and the fixed magnet array 560 is not required; however, the corresponding relationship is that the smaller the gap between the controllable magnet array 550 and the fixed magnet array 560, the greater the magnetic strength (all other factors being equal). Any intervening surface (e.g., the housing of the base 502 or the cover 504) should have a low magnetic permeability so that the flux can pass through. For example, a plastic cover may be provided over either or both of the controllable magnet array 550 and the fixed magnet array 560 to protect and / or hide the magnets.

[0046] In some embodiments, the controllable magnet array 550 includes two independently operable portions: portion 511 and portion 513. Each portion 511, 513 may include a magnet that can be coupled to the EPM 110 ( Figures 1A to 1C )、210( Figure 2 ) or 410( Figure 4 ) array of similar or identical EPMs 510, 512. Similarly, fixed magnet array 560 can be configured into two parts: part 521 and part 523. In part 521, permanent magnet 522 can be as described above with reference to Figure 2The magnets 222a, 222b are arranged in the manner described above so that when the portion 511 of the controllable magnet array 550 is in the open state, an attractive magnetic force is generated between the portion 511 of the controllable magnet array 550 and the portion 521 of the fixed magnet array 560, and when the portion 511 of the controllable magnet array 550 is in the closed state, a negligible force is generated. In the portion 523, the permanent magnet 526 can be Figure 4 The magnets 422a, 422b are arranged in the manner described so that a repulsive magnetic force is generated between the portion 513 of the controllable magnet array 550 and the portion 523 of the fixed magnet array 560 when the portion 513 of the controllable magnet array 550 is in the open state, and a negligible force is generated when the portion 513 of the controllable magnet array 550 is in the closed state.

[0047] In operation, when lid 504 is open (e.g., during normal use of a laptop computer), both portions 511 and 513 of controllable magnet array 550 may be in a closed state, which (as described above) reduces stray magnetic flux near controllable magnet array 550. When lid 504 is moved to or toward a closed position, portion 511 of controllable magnet array 550 may be switched to an open state (while portion 513 remains in a closed state), thereby providing an attractive magnetic force toward portion 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 having portion 511 in an open state). It should be noted that power is consumed only when switching portion 511 (or portion 513) between states, and no power is consumed when having portion 511 in an open state.

[0048] When a user initiates an action to open the lid 504 from a closed position (e.g., by contacting a sensor on the edge of the lid or applying an upward force, etc.), portion 511 of the controllable magnet array 550 may be switched to a closed state to release an attractive force toward portion 521 of the fixed magnet array 560. Additionally, portion 513 of the controllable magnet array 550 may be switched to an open state to generate a repulsive force toward portion 523 of the fixed magnet array 560. The repulsive force may assist the user in lifting the lid 504 or may cause the lid 504 to pop open, thereby creating a gap between the lid 504 and the base 502, which may facilitate further movement of the lid 504 to a desired position for operating the device 500.

[0049] exist Figure 5In the example of , the attraction portions 511 and 521 are positioned farther from the hinge 506 than the repulsion portions 513, 523. This can create a difference between the magnitudes of attraction and repulsion. For example, a longer lever arm requires a greater torque to overcome the attraction magnetic force between portions 511 and 521 and the smaller repulsion force between portions 513 and 523 to move the cover 504 upward. Other arrangements are also possible, including reversing the position of the attraction portion and the repulsion portion or rotating the array so that the two portions are the same distance from the pivot axis defined by the hinge 506.

[0050] In some embodiments, each EPM (e.g., Figure 2 EPM 210 Figure 4 EPM 410, or Figure 5 The coils in the EPM 510, 512) can be pulsed independently. Figure 6A simplified schematic diagram of a control and drive circuit 600 according to some embodiments is shown. The control and drive circuit 600 may include a drive portion 602 that selectively drives a pulse to one or more coils in a plurality of (n) coils 618-1 to 618-n. Each coil 618 may be a coil wound around a low coercive magnetic core in a switchable magnetic element (as described above). In order to controllably drive current through coil 618-1, transistors 622 and 624 are coupled in series between an input voltage and ground. In parallel, transistors 626 and 628 are coupled in series between an input voltage and ground. As shown, one end of coil 618-1 is coupled between transistors 622 and 624, and the other end of coil 618-1 is coupled between transistors 626 and 628. By applying a voltage of a first pattern to gates V1A, V1B, V1C, and V1D, transistors 622 and 628 may be turned on, while transistors 624 and 626 are turned off, thereby allowing current to flow through coil 618-1 in one direction. By applying a voltage of a second pattern to gates V1A, V1B, V1C, and V1D, transistors 622 and 628 may be turned off, while transistors 624 and 626 are turned on, thereby allowing current to flow through coil 618-1 in the other direction. When all transistors 622, 624, 626, and 628 are turned off, no current flows through coil 618-1. The arrangement of transistors 622, 624, 626, and 628 may also prevent ringing from occurring in coil 618-1 after a current pulse. A similar arrangement of transistors may be provided for each coil 618-1 to 618-n. Since the gate voltage is provided to each transistor separately, a pulse may be supplied to each coil independently of any other coil. Capacitor 614 may be provided to generate a current surge, thereby achieving narrower pulses and / or higher peak currents for a given amount of power. Those skilled in the art will appreciate that the peak current in coil 618-1 (or any of coils 618) is a key parameter for changing the direction of magnetic polarization of the magnetic core, and that the specific current required depends on the coil design (e.g., number of turns) and the geometry of the magnetic core. In some embodiments, the pulse duration may be short (e.g., 10 microseconds to 100 microseconds). Shorter pulses allow for faster switching between states; however, very short pulses may generate eddy currents that may reduce the resultant magnetization in the core.

[0051] The control and drive circuit 600 may also include a controller 630, which may be implemented using a programmable microcontroller, an FPGA, an ASIC, etc. The controller 630 may have an input path 632 coupled to receive an event signal. For example, the event signal may indicate that the controllable magnet array or a portion thereof should be switched to another state (e.g., from on to off, or vice versa). In response to the event signal, the controller 630 may output voltages V1A, V1B, V1C, V1D to the gates of transistors 622, 624, 626, 628 to drive (or not drive) the current in coil 618-1, and the same is true for each other coil 618. In this example, the controller 630 may drive the gate voltage of each transistor separately. A pattern or sequence of changes in the voltage output by the controller 630 may be defined to optimize the state transition in the magnet array (or a portion thereof). For example, each coil in the magnet array (or a portion thereof) may receive a current pulse in sequence. The sequential pulses of the coils may reduce peak power consumption compared to the parallel pulses of all coils. As another example, in an array having attractive and repelling portions (e.g., Figure 5 In a controllable magnet array 550), it may be desirable to apply a pulse to the coil to switch one portion to an off state and then switch another portion to an on state.

[0052] The total time to implement a transition between an on state and an off state of an EPM in a controllable magnet array after receiving an event signal using the control and drive circuit 600 depends on various considerations, including the number of coils (assuming that pulses are applied to one coil at a time), the duration of the current pulses, and the time between current pulses. In some embodiments, for an array having four switchable elements in the attraction portion and four switchable elements in the repulsion portion, the total time can be one millisecond or less, short enough that the user does not feel that the response is delayed.

[0053] To further illustrate the operation of the controller 630, Figure 7 and Figure 8 630 is a flow chart showing a process that may be implemented in the controller 630 according to some embodiments. In this example, the controller 630 is used to control Figure 5 A controllable magnet array 550 includes an attraction portion 511 and a repulsion portion 513.

[0054] Figure 7 A flow chart illustrating a process 700 that the controller 630 may perform in response to an event signal indicating a transition to a closed state according to some embodiments.

[0055] At block 702, the controller 630 may receive an event signal (e.g., via input path 632) indicating that the lid 504 is being closed. Depending on the specific implementation and details of the device 500, the "closed" event signal may be generated under various conditions. For example, a force or acceleration sensor in the lid 504 may detect movement toward a closed position, or a user may operate a control (e.g., press a button, touch a particular surface, or issue a voice command) to indicate that the lid 504 should be closed or the magnetic latch should be engaged. In some embodiments, the "closed" event signal may be generated during initial power-on of the device 500 to initialize the magnetic system to a known state.

[0056] At box 704, the controller 630 may pass a current pulse through each coil in the repelling portion 513 of the controllable magnet array 550 to drive the EPM 512 to the closed state. For example, the controller 630 may deliver the current pulse through a given coil by applying an appropriate voltage to the gate of a transistor coupled to the coil, as described above. In some embodiments, the voltage may be controlled so that one coil at a time receives the current pulse. The result of box 704 may be that the repelling portion 513 applies little or no force to the repelling portion 523. At box 706, the controller 630 may pass a current pulse through each coil in the attractive portion 511 of the controllable magnet array 550 to drive the EPM 510 to the open state. For example, the controller 630 may deliver the current pulse through the coil by applying an appropriate voltage to the gate of a transistor coupled to the coil, as described above. In some embodiments, the voltage may be controlled so that one coil at a time receives the current pulse. The result of box 706 may be that the attractive portion 511 applies an attractive force to the attractive portion 521. Thus, the cover 504 can be drawn toward or retained in a closed position adjacent to the base 502 (eg, such that at least a portion of the cover 504 abuts the base).

[0057] Figure 8 A flow chart illustrating a process 800 that the controller 630 may perform in response to an event signal indicating a transition to an open state.

[0058] At block 802, the controller 630 may receive a "release" event signal (e.g., via input path 632) indicating that the magnetic latch should be released. Depending on the specific implementation and details of the device 500, the "release" event signal may be generated under various conditions. For example, a force or acceleration sensor in the cover 504 may detect movement away from a closed position, or a user may operate a control (e.g., press a button, touch a specific surface, or issue a voice command) to indicate that the cover 504 should be opened or the magnetic latch should be released (or disengaged). In some embodiments, the state machine in the component that generates the event signal may be designed so that the "release" event signal is generated only when the previous event signal is a "closed" signal.

[0059] At block 804, the controller 630 may pass a current pulse through each coil in the attraction portion 511 of the controllable magnet array 550 to drive the EPM 510 to the closed state. For example, the controller 630 may deliver the current pulse through a given coil by applying an appropriate voltage on the gate of a transistor coupled to the coil, as described above. In some embodiments, the voltage may be controlled so that one coil at a time receives the current pulse. The result of block 804 may be that the attraction portion 511 stops exerting a significant attraction force on the attraction portion 521. At block 806, the controller 630 may pass a current pulse through each coil in the repulsion portion 513 of the controllable magnet array 550 to drive the EPM 512 to the open state. For example, the controller 630 may deliver the current pulse through the coil by applying an appropriate voltage on the gate of a transistor coupled to the coil, as described above. In some embodiments, the voltage may be controlled so that one coil at a time receives the current pulse. The result of block 806 may be that the repulsion portion 513 exerts a repulsion force on the repulsion portion 523. Thus, the cover 504 can be pushed away from the base 502, thereby creating a gap between the two. From there, the user (or an electrical or mechanical element applying additional force) can further open the cover 504.

[0060] In some embodiments, it may not be desirable to have the switchable magnetic elements of the repelling portion 513 in an on state when the lid 504 is open. For example, when the lid 504 is open, the switchable magnetic elements of the repelling portion 513 may generate sufficient external flux in the on state to interfere with or affect nearby devices or objects (e.g., credit cards). Therefore, at block 808, the controller 630 may receive an "opened" event signal indicating that the lid 504 has been opened to a sufficient extent that the repelling portion 513 no longer facilitates further opening of the lid 504. In response to the "opened" event signal, the controller 630 may pulse a current through each coil in the repelling portion 513 of the controllable magnet array 550 to drive the EPM 512 to a closed state.

[0061] In various embodiments, in addition to or in lieu of the "turned on" event signal at block 808, other events may be used to trigger the switching of the EPM 512 to the closed state. For example, a timer may be used. The timer may be started, for example, when the controller 630 completes block 806 of process 800, and may expire after a specified time (e.g., five seconds, twenty seconds, etc.), after which the controller 630 proceeds to block 808.

[0062] It should be understood that processes 700 and 800 are illustrative, and variations and modifications are possible. In some embodiments, the controller 630 can sequence the gate voltages delivered to the drive portion 602 so that current pulses are only supplied to one coil at a time. In process 700, all EPMs 512 in the repulsive portion 513 can be switched to the off state before any EPM 510 in the attractive portion 511 is switched to the on state, and in process 800, all EPMs 510 in the attractive portion 511 can be switched to the off state before any EPM 512 in the repulsive portion 513 is switched to the on state. In this way, the magnetic system as a whole can smoothly transition from repulsion to neutral, then to attraction, and in the opposite direction.

[0063] Alternatively, if desired, controller 630 may use a different sequence (eg, alternating between switching the magnetic elements in repelling portion 513 to an off state and switching the magnetic elements in attracting portion 511 to an on state).

[0064] In processes 700 and 800, controller 630 need not determine the state of any EPM prior to applying a current pulse; circuit 600 may be designed to deliver a current pulse of sufficient magnitude to switch the magnetic polarization of the EPM to the desired orientation, regardless of 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 may track the current state of a given EPM and adjust the current pulse accordingly; however, additional power may be required to maintain and / or update the stored state information, and the net power savings may be negligible or non-existent.

[0065] The specific event signals and their order are also illustrative. Any number and combination of event signals may be defined, and the controller 630 may be configured (e.g., using programming or logic circuitry) to generate appropriate current pulses for state transitions associated with specific events. The conditions that trigger sending an event signal to the controller 630 may be defined in any desired manner without departing from the scope of the present disclosure.

[0066] In some embodiments, it may not be desirable to disengage the magnetic latch for a long period of time without user activity. For example, after executing block 806 of process 800, at block 808, the controller 630 may wait for an "opened" event signal for a specified timeout period (e.g., ten seconds, thirty seconds, two minutes). If the "opened" event signal is not received within the timeout period, the controller 630 may reengage the magnetic latch, for example, by executing blocks 704 and 706 of process 700. Other combinations and sequences of events may also be supported.

[0067] Other variations are possible. For example, it may be desirable to apply different amounts of attractive or repulsive forces at different times. In some embodiments, this may be accomplished by switching some but not all switchable magnetic elements in one section or the other to an on state while switching other switchable magnetic elements in the same section to an off state. For example, referring to Figure 5 , four EPMs 510 are shown in the attraction portion 511, and four EPMs 512 are shown in the repulsion portion 513. The "full force" attraction state can be generated by operating the controller 630 to switch all four EPMs 510 to the on state and all four EPMs 512 to the off state (e.g., using process 700). The "half force" attraction state can be generated by operating the controller 630 to switch a pair of adjacent EPMs 510 (e.g., the two outermost EPMs 510) to the on state and the two remaining EPMs 510 and all four EPMs 512 to the off state. In a similar manner, full force repulsion states and half force repulsion states can also be generated. An event signal to the controller 630 can indicate which state should be entered, and the controller 630 can generate an appropriate gate voltage sequence in response to a particular event signal to establish a particular state. (For example, appropriate sequences for different states can be stored in a lookup table in association with corresponding event signals.)

[0068] If desired, the controller 630 may include an output signal path that can return information about the current state of the magnetic system to other system components. For example, the controller 630 can send an output signal indicating the on or off state of the switchable magnetic element based on the most recent current pulse delivered to each element. Such information can be used, for example, to activate or deactivate indicator lights, generate notification messages, enable various safety features, etc.

[0069] In embodiments such as the above-described device 500, the dual-acting magnetic system includes different parts, where one pair of parts (e.g., parts 511 and 521) provides a switchable attractive magnetic force and another pair of parts (e.g., parts 513 and 523) provides a switchable repulsive magnetic force. In some alternative embodiments, the switchable magnetic element can be used to provide both attractive and repulsive forces (provided at different times) to the same fixed magnet array. Fig. 9 A simplified perspective view of a dual-acting magnetic system 900 is shown according to some embodiments. The magnetic system 900 includes a controllable magnet array 950 and a fixed magnet array 960. The fixed magnet array 960 can be similar or identical to the fixed magnet array 260 described above. For example, each fixed magnetic element 920 may include permanent magnets 922a, 922b (corresponding to the controllable magnet array 950 and the fixed magnet array 960) having magnetic polarity in opposite directions (as indicated by arrows 923a, 923b). Figure 1A and Figure 1B The permanent magnets 122a, 122b) and the support plate 924 (corresponding to Figure 1A and Figure 1B The permanent magnets 922a, 922b alternate polarity directions along the length of the fixed magnet array 960, and the same permanent magnet can be shared between adjacent fixed magnetic elements 920, for example by centering the permanent magnets 922a, 922b above the pole piece 916.

[0070] The controllable magnet array 950 may 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 may be similar to Figure 1A 1 and may be, for example, an AlNiCo magnet with a coil wound around it. A gap may be provided between the switchable magnets 914 and 918, similar to the gap 115 in FIG. 1. The pole piece 916 (corresponding to Figure 1A and Figure 1B The pole piece 116 and Figure 2 216) may be disposed at both ends of each EPM 910. As in the controllable magnet array 250, the pole pieces 916 may be shared between adjacent EPMs 910. Each switchable magnet 914 and each switchable magnet 918 may be capable of being independently switched (using current pulses as described above) between a first state in which the magnetic polarity of the switchable magnet 914 (or 918) is oriented in the +x direction and a second state in which the magnetic polarity of the switchable magnet 914 (or 918) is oriented in the -x direction.

[0071] In this configuration, each EPM 910 has a first on state, in which both switchable magnets 914 and 918 have magnetic polarity oriented in the +x direction, a second on state, in which both switchable magnets 914 and 918 have magnetic polarity oriented in the -x direction, and a closed 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 the switchable magnets 914 and 918 to switch between the three states.

[0072] By switching the state of the EPM 910 between the three states, both attraction and repulsion can be obtained at different times. For example, in a first configuration in which adjacent EPMs 910 are in an open state oriented in opposite directions, a Figure 2 The magnetic flux shown in FIG. 9 creates an attractive force on the fixed magnet array 960. In this configuration, the magnetic system 900 behaves similarly to Figure 2Similarly, in the second configuration (where each EPM 910 is switched to its other on state), the following may be generated: Figure 1C The magnetic flux shown in FIG. 1 creates a repulsive force on the fixed magnet array 960. In this configuration, the magnetic system 900 behaves similarly to Figure 4 Magnetic system 400. In addition, by switching all EPMs 910 to the off state, a state with minimal force on fixed magnet array 960 (and limited stray flux from controllable magnet array 950) can be achieved. In some embodiments, different strengths of attractive or repulsive magnetic forces can be generated by combining different states of different EPMs 910.

[0073] Although the present invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that variations and modifications are possible. For example, the size of the magnetic elements in the controllable magnet array and the number of EPMs may be varied, and the size and number of permanent magnets in the fixed magnet array may be varied accordingly. In some embodiments, a plurality of controllable magnet arrays may be provided in the magnetic system, and a shared controller may be used to coordinate the operation of these controllable magnet arrays. All materials described herein are exemplary and may be replaced by other materials having appropriate magnetic properties (as described above). In some embodiments, a controllable magnet array of the type described herein may be used in conjunction with a magnetic shunt of an appropriate shape (e.g., a piece of soft magnetic material, such as steel) in place of a fixed magnet array; it will be appreciated by those skilled in the art that in the case of using a magnetic shunt in place of a fixed magnet array, only an attractive magnetic force will be generated.

[0074] In the above examples, the controllable magnet array and the corresponding fixed magnet array have magnets arranged in a straight line. The use of straight lines is for clarity of illustration, and other embodiments may include magnet arrays with curved portions and / or corners. For example, the pole pieces in the controllable magnet array using EPM can be shaped to provide a curvature or corner, and the magnets in the corresponding fixed magnet array can be arranged to correspond to the position of the pole pieces.

[0075] Magnetic systems of the type described herein may be applied to any situation where the ability to selectively exert attractive and / or repulsive forces between a first object or surface and a second object or surface is desired. The example of opening and closing the lid of a laptop computer is described above; however, many other applications are possible. Other example applications include opening and closing doors, operating mechanical switches or relays, removably attaching one object to another (e.g., a portable device that can be held on a stand), and the like.

[0076] All processes described herein are also illustrative and can be modified. Operations can be performed in a different order than described within the scope of logic permission; the above operations can be omitted or combined; and operations not explicitly described above can be added.

[0077] Although various circuits and components are described herein with reference to specific blocks, it should be understood that these blocks are defined for convenience of description and are not intended to imply a specific physical arrangement of component parts. Each block does not have to correspond to physically different components, and the same physical components can be used to implement various aspects of multiple blocks. Components described as dedicated circuits 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 that implement the operations described herein. Components described as processors or microprocessors can be configured to perform the operations described herein by providing suitable program codes. Depending on the way the initial configuration is obtained, various blocks may or may not be reconfigurable. Embodiments of the present invention can be implemented in various devices including electronic devices implemented using a combination of circuits and software.

[0078] It should be understood that directional terms are used herein to simplify the description, such as "upper", "lower", "above", "below", etc. Such terms should be understood to distinguish different directions in a coordinate system that can have any orientation in space.

[0079] All numerical values ​​and ranges provided herein are exemplary and may be modified.Unless otherwise indicated, the drawings are to be understood as schematic and not drawn to scale.

[0080] Therefore, although the invention has been described with respect to specific embodiments, it should be understood that the invention is intended to cover all modifications and equivalents within the scope of the following claims.

[0081] CROSS-REFERENCE TO RELATED APPLICATIONS

[0082] This application claims priority to U.S. Provisional Application No. 63 / 541,259, filed on September 28, 2023, and U.S. Non-Provisional Patent Application No. 18 / 893,169, filed on September 23, 2024, which are hereby incorporated by reference in their entireties for all purposes.

Claims

1. A magnetic system, comprising: A controllable magnet array, the controllable magnet array comprising a plurality of electropermanent magnets arranged end to end, wherein each electropermanent magnet comprises: a first permanent magnet disposed proximate the interface surface and having a fixed magnetic orientation along the longitudinal axis, wherein the fixed magnetic orientations of the first permanent magnets in adjacent electropermanent magnets are antiparallel to each other; a switchable magnet comprising a core made of a magnetic material and a coil wound around the core along a longitudinal axis of the core, wherein the switchable magnet is positioned on a distal side of the first permanent magnet and spaced apart from the first permanent magnet; and a pole piece disposed at each longitudinal end of the first permanent magnet and the switchable magnet, the pole piece being made of a soft magnetic material and extending across end surfaces of the first permanent magnet and the electropermanent magnet, wherein the pole piece is shared between adjacent electropermanent magnets in the controllable magnet array; a fixed magnet array comprising an array of second permanent magnets arranged parallel to the interface surface such that each second permanent magnet is aligned with one of the pole pieces of the controllable magnet array, wherein adjacent second permanent magnets have fixed magnetic polarizations in opposite directions towards or away from the interface surface; and a control and drive circuit coupled to each of the coils and configured to supply current pulses to the coils to switch the magnetic polarization direction of the core of the electropermanent magnet, thereby switching the electropermanent magnet between an on state and an off state, wherein in the on state, the magnetic polarization direction of the core is parallel to the magnetic polarization of the first permanent magnet, and in the off state, the magnetic polarization direction of the core is antiparallel to the magnetic polarization of the first permanent magnet, wherein the control and drive circuit is configured to supply current pulses to different coils independent of each other.

2. A magnetic system according to claim 1, wherein at least some of the second permanent magnets in the fixed magnet array are aligned relative to the first permanent magnets so that when the electropermanent magnet is in the on state, an attractive magnetic force is generated between the fixed magnet array and the controllable magnet array.

3. The magnetic system of claim 2, wherein the control and drive circuit is further configured to modify the magnitude of the attractive magnetic force by switching a subset of the electropermanent magnets between the on state and the off state.

4. The magnetic system of claim 1 , wherein at least some of the second permanent magnets in the fixed magnet array are aligned relative to the first permanent magnets so that when the electropermanent magnets are in the on state, a repulsive magnetic force is generated between the fixed magnet array and the controllable magnet array.

5. The magnetic system of claim 1 , wherein the controllable magnet array and the fixed magnet array comprise: a first portion, in which the second permanent magnet is aligned relative to the first permanent magnet such that when the electropermanent magnets in the first portion of the controllable magnet array are in the on state, an attractive magnetic force is generated between the first portion of the fixed magnet array and the first portion of the controllable magnet array; and and a second part, in which the second permanent magnet is aligned relative to the first permanent magnet so that when the electropermanent magnet in the second part of the controllable magnet array is in the on state, a repulsive magnetic force is generated between the second part of the fixed magnet array and the second part of the controllable magnet array.

6. The magnetic system of claim 5, wherein the control and drive circuit is configured to supply current pulses such that: When the electropermanent magnets in the first portion of the controllable magnet array are in the on state, the electropermanent magnets in the second portion of the controllable magnet array are in the off state; and When the electropermanent magnets in the second portion of the controllable magnet array are in the on state, the electropermanent magnets in the first portion of the controllable magnet array are in the off state.

7. The magnetic system of claim 1, wherein the control and drive circuit is configured such that the current pulses are supplied sequentially to the coils of different ones of the switchable magnets.

8. The magnetic system of claim 1 wherein the control and drive circuit includes a gating circuit to prevent ringing in the coil following a current pulse.

9. The magnetic system of claim 1, wherein the first permanent magnet is made of a first magnetic material having a first coercivity, and the switchable magnet is made of a second magnetic material having a second coercivity, the second coercivity being lower than the first coercivity.

10. A device, comprising: A first object having a first interface surface, the first object comprising a controllable magnet array, the controllable magnet array comprising a plurality of electropermanent magnets arranged end-to-end proximate the first interface surface, wherein each electropermanent magnet comprises: a first permanent magnet disposed proximate the first interface surface and having a fixed magnetic orientation along a longitudinal axis, wherein the fixed magnetic orientations of the first permanent magnets in adjacent electropermanent magnets are antiparallel to each other; a switchable magnet comprising a core made of a magnetic material and a coil wound around the core along a longitudinal axis of the core, wherein the switchable magnet is positioned on a distal side of the first permanent magnet and spaced apart from the first permanent magnet; and a pole piece disposed at each longitudinal end of the first permanent magnet and the switchable magnet, the pole piece being made of a soft magnetic material and extending across end surfaces of the first permanent magnet and the electropermanent magnet, wherein the pole piece is shared between adjacent electropermanent magnets in the controllable magnet array; a second object having a second interface surface, the second object being positionable relative to the first object such that the second interface surface abuts the first interface surface, the second object comprises a fixed magnet array, the fixed magnet array comprising an array of second permanent magnets, the array of second permanent magnets being arranged proximate the second interface surface such that each second permanent magnet is aligned with one of the pole pieces of the controllable magnet array, wherein adjacent second permanent magnets have fixed magnetic polarizations in opposite directions towards or away from the interface surface; and a control and drive circuit coupled to each of the coils and configured to supply current pulses to the coils to switch the magnetic polarization direction of the core of the electropermanent magnet, thereby switching the electropermanent magnet between an on state and an off state, wherein in the on state, the magnetic polarization direction of the core is parallel to the magnetic polarization of the first permanent magnet, and in the off state, the magnetic polarization direction of the core is antiparallel to the magnetic polarization of the first permanent magnet, wherein the control and drive circuit is configured to supply current pulses to different coils at different times.

11. The apparatus of claim 10, wherein the control and drive circuitry is disposed within the first object.

12. The device of claim 10, wherein the first object is a base including a keyboard oriented toward the first interface surface, and the second object is a cover including a display oriented toward the second interface surface, and wherein the first object and the second object are connected by a hinge such that rotational movement of the first object or the second object about the hinge causes the first interface surface and the second interface surface to move toward or away from each other.

13. The apparatus of claim 10, wherein at least some of the second permanent magnets in the fixed magnet array are aligned relative to the first permanent magnets so that when the electropermanent magnet is in the on state, an attractive magnetic force is generated between the fixed magnet array and the controllable magnet array.

14. The apparatus of claim 10, wherein at least some of the second permanent magnets in the fixed magnet array are aligned relative to the first permanent magnets so that when the electropermanent magnets are in the on state, a repulsive magnetic force is generated between the fixed magnet array and the controllable magnet array.

15. The apparatus of claim 10, wherein the controllable magnet array and the fixed magnet array comprise: a first portion, in which the second permanent magnet is aligned relative to the first permanent magnet such that when the electropermanent magnets in the first portion of the controllable magnet array are in the on state, an attractive magnetic force is generated between the first portion of the fixed magnet array and the first portion of the controllable magnet array; and and a second part, in which the second permanent magnet is aligned relative to the first permanent magnet so that when the electropermanent magnet in the second part of the controllable magnet array is in the on state, a repulsive magnetic force is generated between the second part of the fixed magnet array and the second part of the controllable magnet array.

16. The device of claim 15, wherein the control and drive circuit is configured to supply current pulses such that: When the electropermanent magnets in the first portion of the controllable magnet array are in the on state, the electropermanent magnets in the second portion of the controllable magnet array are in the off state; and When the electropermanent magnets in the second portion of the controllable magnet array are in the on state, the electropermanent magnets in the first portion of the controllable magnet array are in the off state.

17. The apparatus of claim 15, wherein the control and drive circuit is configured such that: In response to receiving a closing event signal, the control and drive circuit first supplies a current pulse to switch the electropermanent magnets in the second portion to the closed state, and then supplies a current pulse to switch the electropermanent magnets in the first portion to the open state; and In response to receiving a release event signal, the control and drive circuit first supplies a current pulse to switch the electropermanent magnets in the first portion to the closed state, and then supplies a current pulse to switch the electropermanent magnets in the second portion to the open state.

18. A magnetic system, comprising: A controllable magnet array, the controllable magnet array comprising a plurality of electropermanent magnets placed end to end, wherein each electropermanent magnet comprises: a first switchable magnet comprising a first core made of a magnetic material and a first coil wound around the first core along a longitudinal axis of the first core, wherein the first switchable magnet is disposed proximate to an interface surface; a second switchable magnet comprising a second core made of a magnetic material and a second coil wound around the second core along a longitudinal axis of the second core, wherein the second switchable magnet is positioned on a distal side of the first switchable magnet and spaced apart from the first switchable magnet; and a pole piece disposed at each longitudinal end of the first switchable magnet and the second switchable magnet, the pole piece being made of a soft magnetic material and extending across end surfaces of the first switchable magnet and the second switchable magnet, wherein the pole piece is shared between adjacent electropermanent magnets in the controllable magnet array; a fixed magnet array comprising an array of permanent magnets arranged parallel to the interface surface such that each permanent magnet is aligned with one of the pole pieces of the controllable magnet array, wherein adjacent permanent magnets have magnetic polarization in opposite directions towards or away from the interface surface; and a control and drive circuit coupled to each of the first coils and each of the second coils and configured to supply current pulses to the first coil and the second coil so as to switch the electropermanent magnet between a first on state, a second on state and an off state, wherein in the first on state the magnetic polarizations of the first switchable magnet and the second switchable magnet are parallel and in a first longitudinal direction, in the second on state the magnetic polarizations of the first switchable magnet and the second switchable magnet are parallel and in a second longitudinal direction opposite to the first longitudinal direction, and in the off state the magnetic polarizations of the first switchable magnet and the second switchable magnet are in antiparallel longitudinal directions.

19. A magnetic system according to claim 18, wherein when all of the electropermanent magnets are in the first on state or the second on state, the magnetic polarizations of the first switchable magnet and the second switchable magnet in adjacent switchable magnetic elements are antiparallel to each other, and the pole piece guides the magnetic flux toward or away from the fixed magnet array, and when all of the electropermanent magnets are in the off state, the pole piece guides the magnetic flux within the switchable magnetic element.

20. The magnetic system of claim 19, wherein the permanent magnets in the fixed magnet array are arranged such that when the electropermanent magnets are in the first on-state, the magnetic flux produces an attractive force on the fixed magnet array, and when the electropermanent magnets are in the second on-state, the magnetic flux produces a repulsive force on the fixed magnet array.

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