Improved electrical interface for motors

Abstract

The present disclosure relates to an electrical interface, an electric motor, a linear electric motor, and a method for manufacturing the electrical interface. The electrical interface includes a first portion having a first conductive surface, a second portion having a second conductive surface, and at least one flexible conductive band configured to transmit power between the first and second conductive surfaces, the second portion configured to move relative to the first portion, the at least one flexible conductive band disposed between the first and second conductive surfaces, and the at least one flexible conductive band configured to maintain electrical contact between the first and second conductive surfaces as the second portion moves relative to the first portion.

Description

[Technical Field]

[0001] The present invention relates to an electrical interface suitable for use with an electric motor, and in particular to an arrangement for effecting an electrical connection between two relatively movable members of such a motor.

[0002] It is contemplated that the present invention may also be used as an electrical interface in non-motor applications wherever power needs to be transferred from a stationary object to a moving (eg, rotating) object. [Background technology]

[0003] Conventional rotary electric motors are of two types. In the first type, a power source is connected by means of brushes to coils on an armature that is arranged to rotate around or within a stator in the form of one or more permanent magnets. Rotation of the armature relative to the brushes also serves to exchange current between the coils. In the second type, the rotor contains multiple permanent magnets and the stator contains the coils and associated electrical circuitry that controls the switching of power between the coils.

[0004] The first type of challenge involves the use of brushes to connect the power supply to the rotating armature, which inevitably results in some degree of arcing and associated brush wear, as well as unintended consequences such as electromagnetic interference, usually radio frequency, and audible noise.

[0005] The problems associated with brushes do not arise in the second type of motor, but the second type of motor must be constructed so that the rotating magnets can withstand the large inertial stresses typically encountered in high-speed motors.

[0006] Linear motors, such as uncommutated linear actuators, are also known. An uncommutated linear actuator (also known as a voice coil linear actuator, or, when a DC signal is applied, an uncommutated DC linear actuator) is a direct-drive linear actuator. It consists of a permanent magnetic field assembly and a coil assembly, arranged so that a current flowing through the coil assembly interacts with the permanent magnetic field generated by the permanent magnetic field assembly to generate a force vector perpendicular to the direction of the current.

[0007] Typical non-commutated linear actuators have several drawbacks. First, when the moving part within the actuator is at different positions along its length of travel, different forces are generated due to the interaction of the current flowing through the coil assembly with the permanent magnetic field. Compensating for these force differences requires increased motor control complexity. Furthermore, these devices rely on the alignment of the moving part relative to the fixed part, which is critical to achieving the desired force. However, typical non-commutated linear actuators offer inadequate protection against external forces such as mechanical shock, which can cause misalignment between the fixed and moving parts. Finally, when the coil assembly of a non-commutated linear actuator is part of the actuator's moving part, additional issues arise related to the reliability of the electrical connection to the coil assembly. For example, if wires are used to connect to the coil assembly, the constant movement of the moving part can rapidly wear the wires, potentially leading to motor failure.

[0008] It is therefore desirable to provide an arrangement to overcome or at least reduce the problems of conventional electric motors. Summary of the Invention

[0009] According to a first aspect of the present invention, there is provided an electrical interface including a first portion having a first conductive surface, a second portion having a second conductive surface, and at least one flexible conductive band configured to transfer power between the first and second conductive surfaces. The second portion is configured to move relative to the first portion. The at least one flexible conductive band is disposed between the first and second conductive surfaces. Finally, the at least one flexible conductive band is configured to maintain constant electrical contact between the first and second conductive surfaces as the second portion moves relative to the first portion.

[0010] By providing an electrical interface with flexible conductive bands instead of a brushed arrangement for a rotary motor, the advantages of the prior art rotary motor can be achieved without providing brushes and without the problems inherent in the second type of prior art motor. Additionally, the electrical interface reduces wear and stress on the linear actuator because there are no joints between the wiring and the moving parts of the linear actuator.

[0011] A "flexible conductive band" may refer to a strip or loop of material. The conductive band itself may be at least partially formed from a conductive material, or there may be a conductive element on, around, or connected to a non-conductive substrate of the conductive band. "Flexible" may further be understood to refer to the ability of the conductive band to bend or deform without breaking.

[0012] In some embodiments, the flexible conductive band is a resilient element that can be deformed (e.g., compressed) from a rest state to an assembled state when disposed between the first and second conductive surfaces. In such an assembled state, the flexible conductive band can be subjected to a mechanical strain that returns the flexible conductive band to its rest state. This characteristic improves the electrical connection between the first and second conductive portions by maximizing the surface area of ​​electrical contact.

[0013] In some embodiments, the at least one flexible conductive band is configured to mechanically interact with the first portion at a first contact area and to mechanically interact with the second portion at a second contact area, such that when the second portion moves relative to the first portion, the flexible conductive band is configured to travel a predetermined path along the first conductive surface.

[0014] In some embodiments, the at least one flexible conductive band is configured to move in a rolling motion to travel the predetermined path.

[0015] A part moving "relative to" another part is understood to represent both rotational motion (a first part rotating relative to a second part, or vice versa) and translational or linear motion (a first part moving in a linear direction relative to a second part).

[0016] It is also understood that "rotational motion" refers to motion in which the flexible conductive band rotates about a central axis of the flexible conductive band (similar to the rotational motion experienced by other "bands" such as vehicle wheels or treadmill belts), with the central axis translating in a first direction (to enable the rotational motion). An example of this rotational motion can be considered a continuous track used for vehicle propulsion.

[0017] In some embodiments, the first portion comprises a first insulator, the second portion comprises a second insulator, the first conductive surface is mounted on the first insulator, and the second conductive surface is mounted on the second insulator.

[0018] In some embodiments, the first conductive surface is disposed within the track of the first insulator and the second conductive surface is disposed within the track of the second insulator.

[0019] Insulators can be present in the first and second parts to provide isolation between the current paths of the corresponding parts and surrounding electronics and the remainder of the first and second parts (which may include further conductive paths that need to be kept separate to avoid the risk of short circuits). When the electrical interface is incorporated as part of a wider electrical component, insulators are also important to isolate the conductive surfaces from adjacent components (such as the metal chassis of a motor that is grounded for safety).

[0020] "Track" is understood to refer to a groove or channel in an insulator, and is therefore considered to refer to an arrangement in which a conductive surface is surrounded on at least one side by a wall of insulating material.

[0021] In some embodiments, the first insulator, the second insulator, or both the first and second insulators include at least one protrusion, and the at least one conductive band includes at least one notch configured to interact with the at least one protrusion as the flexible conductive band advances along the predetermined path.

[0022] In some embodiments, the first insulator, the second insulator, or both the first and second insulators include a plurality of protrusions, and the at least one conductive band comprises a plurality of notches configured to interact with the plurality of protrusions as the at least one flexible conductive band advances along the predetermined path.

[0023] A protrusion may refer to a feature that extends beyond the surface of the insulator into a predetermined path along which the flexible conductive band travels. If a conductive surface is located within a corresponding track in the insulator, the protrusion may extend into the track. A notch may refer to the removal of material in the flexible conductive band. A notch may refer to the removal of material along at least one edge of the flexible conductive band (e.g., one or more notches may be formed in the side edges of a strip of material such that the top and bottom edges of the strip are connected to each other to form a band, resulting in a flexible conductive band with at least one notch formed in its edge).

[0024] The protrusions and notches can be any shape, as long as the shape of the protrusion fits within the notch, coupling the corresponding insulator to the flexible conductive band and improving the mechanical interaction between the insulator and the flexible conductive band. One advantage of having at least one protrusion on the insulator and at least one notch on the flexible conductive band is that slippage between the first and second portions is reduced. In other words, because the protrusion on the insulator is configured to interact with the corresponding notch on the flexible conductive band, the flexible conductive band can more easily engage in a rotational motion when the first portion moves relative to the second portion. This improves the electrical connection between the first and second portions and also reduces the amount of friction between the flexible conductive band and each of the first and second portions.

[0025] It is also important to minimize slippage between the flexible conductive band and the first and second portions to improve electrical performance. This is because current can flow across the electrical interface during operation. Current can enter the flexible conductive band along the contact surface (i.e., the surface formed between the first portion and the flexible conductive band). Similarly, current can exit the flexible conductive band along the second contact surface (i.e., the surface formed between the second portion and the flexible conductive band). These contact surfaces can result in uneven current flow along the contact surface, potentially resulting in current constriction (also known as current crowding).

[0026] The absence of protrusions / notches increases the likelihood of slippage between the flexible conductive band and the first and second parts, leading to increased friction and increased constriction of the current (leading to further power loss and risk of damage due to undesirable uneven heating of the parts).

[0027] Therefore, this uneven current can be mitigated by limiting the amount of slippage between the members, an effect that is particularly advantageous when the electrical interface is implemented in a high-power (>1 kW) motor.

[0028] Furthermore, when multiple flexible conductive bands are present in the same predetermined path (i.e., in the same track of the insulator and in contact with the same conductive surface), the at least one protrusion and at least one notch are advantageous for ensuring proper spacing between the multiple flexible conductive bands. That is, when two flexible conductive bands roll along the same conductive surface and come into contact with each other, additional friction at the interface can degrade performance. The protrusions and notches address this issue by ensuring proper spacing between the bands when multiple bands are present.

[0029] While the above advantages are achieved with a single protrusion and single notch, the effects are enhanced when there are multiple protrusions and corresponding notches. When multiple such elements are present, the protrusions are evenly distributed along the length of a given path (i.e., the width between the protrusions is uniform). The notches are evenly distributed around the circumference of the corresponding flexible conductive band and have the same uniform width as the width of the protrusions.

[0030] The protrusions and notches can be located at any suitable location along the insulator / flexible conductive band. For example, the flexible conductive band can include notches on only one edge. Alternatively, the flexible conductive band can include notches on both edges. Such an embodiment can improve ease of manufacturing because it is not necessary to ensure that the band is properly oriented relative to the insulator (if the protrusions are only along one edge of the insulator).

[0031] In some embodiments, the at least one flexible conductive band comprises a plurality of flexible conductive bands.

[0032] One advantage of having multiple flexible conductive bands is that they increase the maximum power that can be transferred from the first section to the second section, which, if implemented within a motor, can improve the maximum torque available during operation.

[0033] In some embodiments, the at least one flexible conductive band comprises a flexible polymeric substrate having a conductive coating, optionally the flexible polymeric substrate comprises polyimide.

[0034] One advantage of flexible polymer substrates, such as polyimide plastic film, is that the material can withstand many flexing and bending cycles without breaking. Polyimide films can also be coated with a number of highly conductive coatings and finishes (e.g., one conductive coating can include graphene). As a finish, the substrate can be electroplated by electroless plating or ion deposition in solution. Alternative conductive coatings can include metals such as copper (e.g., applied by electrodeposition in copper chloride or copper sulfate solutions), nickel, palladium, ruthenium, or other suitable metals. Multiple plating and coating techniques on flexible plastic substrates are particularly advantageous for mass-produced miniature motors, reducing manufacturing-related costs, because such flexible conductive bands can further reduce reliance on expensive metals currently used in such motors.

[0035] In some cases, a polymeric substrate (also referred to herein as a carrier substrate) can be surface treated to enhance the "seeding" of electroless metals, and the substrate can then be placed in a bath of a solution of such electroless metal (e.g., electroless copper or nickel) until the metal deposits on the plastic film.

[0036] The polymer substrate may be pre-formed into the loop shape of the flexible conductive band, i.e., the flexible polymer substrate can be manufactured as a single piece (i.e., without joints), thus achieving further manufacturing improvements, which is particularly advantageous for mass-produced electric motors.

[0037] Additional polymeric films other than polyimide are also contemplated in this disclosure, including PET.

[0038] In some embodiments, the at least one flexible conductive band comprises a flexible metal substrate, optionally wherein the flexible metal substrate comprises an amorphous metal.

[0039] The flexible metal substrate may be understood to refer to a flexible metal foil. The flexible metal substrate may include stainless steel. The flexible metal substrate may further be coated on at least one side (e.g., coated on at least one side with titanium nitride). The titanium nitride may be applied to the stainless steel substrate by any method known to those skilled in the art, including vacuum deposition or sputtering.

[0040] One advantage of flexible metal substrates is that they can provide a low coefficient of friction, which improves long-term operation of the flexible conductive band and limits wear.

[0041] In some embodiments, the at least one flexible conductive band is formed by welding at least one of the flexible metal substrates to a continuous loop of conductive material, and optionally, one flexible conductive band is braided during the welding operation to form a weld joint having comb teeth.

[0042] A "strip" of flexible substrate refers to a narrow section of flexible substrate whose ends can be joined to form a flexible band. In one example, the metal strip can be laser cut from a single piece of foil (to limit edge burrs on the resulting strip).

[0043] The strip can be formed into a band by welding the ends of the strip together. The strip can be held in the correct shape (i.e., the ends are held adjacent to each other) by a cylindrical former (made of a material that does not interfere with the welding process, such as ceramic or glass). The welding process can be performed by a laser.

[0044] The corresponding ends of the joined strips may include comb teeth, which can increase the strength of the weld without increasing the thickness of the weld bead. Additionally, the weld bead can be polished and ground to further improve the smoothness of the band.

[0045] In some embodiments, the at least one flexible conductive band comprises a thin film conductive coating.

[0046] A thin film conductive coating can be further applied to extend the life of the band, thereby improving the frictional effectiveness of both the band and the associated tracks of the first and second portions. Conductive coatings can also be used to improve the electrical behavior of the surface and enhance current carrying access at the interface region.

[0047] The thin-film conductive coating material can be any material that does not undergo significant work hardening. It can also be a material that has a high level of adhesion and minimizes heat loss (due to low electrical resistance). Examples of coatings that can be used include titanium nitride and titanium carbonitride. Alternatively, coatings of amorphous metals (also known as glassy metals) can be used. These materials have a random atomic arrangement that does not undergo work hardening. Work hardening refers to the phenomenon that occurs when certain materials (e.g., most metals) are bent or repeatedly bent, and it is understood that the crystalline structure of the material changes, leading to embrittlement.

[0048] In some embodiments, the first portion is annular, the second portion is annular, and the second portion is configured to rotate relative to the first portion.

[0049] In some embodiments, the first annular portion has a first central axis passing through a center of the first annular portion in a direction transverse to the plane of the first annular portion, the second annular portion has a second central axis passing through a center of the second annular portion in a direction transverse to the plane of the second annular portion, the first central axis being aligned with the second central axis, and the flexible conductive band is configured to rotate about the central axis to travel the predetermined path.

[0050] A central axis (an axis passing through the center of the corresponding annular portion) is understood to refer to an axis about which the ring has rotational symmetry and which passes through the center of the ring (the center being relatively equidistant from all points on the inner diameter of the ring and / or all points on the outer diameter of the ring).

[0051] It is also understood that a first central axis is "aligned" with a second central axis means that the first axis and the second axis are coincident with each other (the first and second annular portions share a central axis).

[0052] In some embodiments, the first annular portion and the second annular portion have different outer diameters and are arranged concentrically with one another, and power is configured to flow between the first conductor and the second conductor toward or away from the central axis.

[0053] The outer diameter is understood to refer to the distance from the center point of the ring to the outer edge extending along the outer periphery. Similarly, the inner diameter refers to the distance from the center point of the ring to the closer inner edge extending along the inner periphery.

[0054] It is also noted that the two ring portions may not only have different outer diameters, but also different inner diameters. In particular, one of the two ring portions may have an outer diameter that is smaller than the inner diameter of the other ring portion (the smaller ring may fit completely within the larger ring and remain concentric along the same axis). This allows current to flow radially between the first and second ring portions (i.e., toward or away from the center point of the two rings).

[0055] In one example, the first annular portion may be smaller than the second annular portion, or the first annular portion may be larger than the second annular portion.

[0056] When the flexible conductive band is configured to rotate about a central axis to travel a predetermined path, it is understood that the flexible conductive band moves in a rotational motion. That is, the flexible conductive band can be thought of as moving in a circular rotational motion around the inner circumference of the outer, larger ring (and the outer circumference of the inner, smaller ring). More specifically, because the second portion is configured to rotate relative to the first portion and one of the ring portions is disposed concentrically with respect to the other (and thus within or surrounding the other ring), the flexible conductive band can be configured to move around the outermost surface of the inner ring and around the innermost surface of the outer ring.

[0057] In some embodiments, the first annular portion and the second annular portion have essentially the same diameter and are spaced a predetermined distance from the central axis such that power flows between the first conductor and the second conductor along the central axis.

[0058] When the flexible conductive band is configured to rotate about a central axis to travel a predetermined path, it is understood that the flexible conductive band also undergoes rotational motion. That is, the flexible conductive band can be considered to be rotating in a circular manner along a planar surface. More specifically, when the second portion is configured to rotate relative to the first portion, and the first and second portions are each annular, the flexible conductive band can be configured to move clockwise or counterclockwise in the region between two adjacent annular portions.

[0059] In some embodiments, the first portion further includes a third conductive surface, the second portion further includes a fourth conductive surface, and the electrical interface further includes at least one second flexible conductive band that transfers power between the third conductive surface and the fourth conductive surface, the at least one second flexible conductive band being disposed between the third conductive surface and the fourth conductive surface, and the at least one second flexible conductive band being configured to maintain electrical contact between the first conductive surface and the second conductive surface at all times as the second portion moves relative to the first portion.

[0060] Such a configuration is useful when bipolar operation of an electrical device is required, or more generally when two separate signals need to be transmitted over the same electrical interface. In this way, a first signal (e.g., V+) can be transmitted across a flexible conductive band (i.e., a first flexible conductive band) and a second signal (e.g., V−) can be transmitted across a second flexible conductive band.

[0061] In some embodiments, the at least one second flexible conductive band comprises a plurality of second flexible conductive bands.

[0062] Again, the same advantages offered by multiple flexible conductive bands are achieved.

[0063] The present invention also provides an electric motor including a fixed member, a rotatable member configured to rotate relative to the fixed member, and an electrical interface. The electrical interface may be any one of the electrical interfaces described in the above embodiments. The fixed member includes an input terminal configured to receive electrical power. The rotatable member includes a plurality of conductive windings. The electrical interface is configured such that the first portion is electrically connected to the input terminal and the second portion is electrically coupled to the plurality of conductive windings, and the electrical interface is configured to transfer the electrical power from the input terminal to the plurality of conductive windings.

[0064] In some embodiments of the electric motor, the motor is a DC motor, and the rotatable member further includes an electric circuit connected to the plurality of conductive windings and configured to generate a motor drive signal for each of the plurality of conductive windings based on received electrical power, and the at least one flexible conductive band and / or the at least one second conductive band are configured to transmit the electrical power to the electric circuit, and the electric circuit is driven by the electrical power.

[0065] Such electric motors are advantageous because they have a low amount of friction between the rotatable member (also known as the rotor) and the stationary member (also known as the stator), which allows the motor to have an increased power output compared to a similarly sized motor with brushes.

[0066] Such motors have an advantage over brushed motors because they have a longer motor lifespan: due to the interaction between the motor brushes and the rotor, the brushes on a typical DC motor wear out quickly, resulting in a poor electrical connection between the stator and the motor (and consequently causing the motor to stop working).

[0067] Also provided is a linear electric motor including a fixed member, a longitudinally movable member configured to move relative to the fixed member, and an electrical interface. The electrical interface may be any one of the electrical interfaces described in the above embodiments. The fixed member includes an input terminal configured to receive the power. The longitudinally movable member includes at least one conductive winding. The electrical interface has a first portion electrically connected to the input terminal and a second portion electrically coupled to the plurality of conductive windings, and the electrical interface is configured to transfer the power from the input terminal to the plurality of conductive windings.

[0068] In some embodiments of the linear electric motor, the linear electric motor is an uncommutated linear actuator, and the fixed member further includes a permanent magnet assembly, and the at least one flexible conductive band and / or the at least one second conductive band are configured to transfer electrical power to at least one conductive winding on the longitudinally movable member, and current flowing in the conductive windings due to applied electrical power is configured to interact with a permanent magnetic field generated by the permanent magnet assembly to generate a force that moves the longitudinally movable member.

[0069] In linear motors (such as voice coil actuators), the electrical interface of the present invention replaces wired connections to conductive windings on the longitudinally movable members. These wires are subject to significant stress during repeated operation of the linear motor. Thus, the linear electric motor of the present invention is advantageous in that it reduces wear on the members and extends the life of the motor itself.

[0070] The present invention also provides a method of manufacturing an electrical interface, the method comprising: forming the at least one flexible conductive band from a flexible polymeric or metallic substrate; and disposing the at least one flexible conductive band between and in electrical contact with the first conductive surface of the first portion and the second conductive surface of the second portion. [Brief explanation of the drawings]

[0071] Advantageous embodiments of the invention will now be described with reference to the accompanying drawings. [Figure 1A] FIG. 1 is an exploded view of an exemplary electrical interface according to the present invention. [Figure 1B] FIG. 1B is another exploded view of the exemplary electrical interface shown in FIG. 1A. [Figure 2] FIG. 1C illustrates the exemplary electrical interface shown in FIGS. 1A and 1B in an assembled configuration with the cover of the electrical interface partially removed. [Figure 3A] FIG. 1C is a perspective view of an exemplary electric motor including the electrical interface shown in FIGS. 1A and 1B. [Figure 3B] FIG. 1C is a perspective view of an exemplary electric motor including the electrical interface shown in FIGS. 1A and 1B. [Figure 4A] FIG. 10 is an exploded view of an alternative electrical interface according to the present invention. [Figure 4B] FIG. 4B is another exploded view of the alternative electrical interface shown in FIG. 4A. [Figure 5A] 1 is a perspective view of an example of a notched flexible conductive band for use in an electrical interface according to the present invention; [Figure 5B] 1 is a perspective view of an example of a notched flexible conductive band for use in an electrical interface according to the present invention; [Figure 6] FIG. 1 is an exploded view of an exemplary linear electric motor including an electrical interface in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0072] In the following description, the terms "first," "second," "third," "fourth," "primary," and "secondary" are not intended to be limiting, but rather are used to distinguish different elements from one another. The proximal direction is considered to be the input side of the electrical interface, while the distal direction is considered to be the output side of the electrical interface. For the avoidance of doubt, the longitudinal axis of an electrical interface or electric motor is considered to be the axis running in the direction between the proximal end (i.e., power input side) and the distal end of the electric motor. For linear motors, this longitudinal axis follows the direction of movement of the motor.

[0073] 1A and 1B show a first embodiment of an electrical interface 100, the components of which are shown in an exploded view. An assembled view of the first embodiment of the electrical interface 100 is also shown in FIG.

[0074] Electrical interface 100 comprises a first portion 110 that includes at least a portion of a chassis (not shown) of the electrical interface. A first conductive surface 121 and a third conductive surface 123 are attached to an inner surface of first portion 110. Electrical interface 100 also comprises a second portion 120 that is configured to rotate relative to first portion 110. A second conductive surface 122 and a fourth conductive surface 124 are attached to an inner surface of second portion 120.

[0075] A plurality of flexible conductive bands 150 are provided for transmitting electrical signals from the first conductive surface 121 of the first portion 110 to the second conductive surface 122 of the second portion 120 of the electrical interface 100.

[0076] A plurality of second flexible conductive bands 160 are provided for transmitting electrical signals from the third conductive surface 123 of the first portion of the electrical interface 100 to the fourth conductive surface 124 of the second portion 120.

[0077] It is understood that the flexible conductive band and the second flexible conductive band may be of similar design. Throughout this specification, when structural features associated with one or more flexible conductive bands are described, it is understood that similar structural features are also present in the one or more second flexible conductive bands. Similarly, when structural features associated with one or more flexible conductive bands are described in the context of a rotary electrical interface (where electrical energy is transferred from a fixed portion to a rotating portion), the same structural features may also apply to a linear electrical interface (where electrical energy is transferred from a fixed portion to a longitudinally movable portion).

[0078] In this case, first conductive surface 121 is connected to a first input terminal, and first conductive surface 121 can receive an electrical signal. Similarly, third conductive surface 123 is connected to a second input terminal, and third conductive surface 123 can be connected to another electrical signal.

[0079] First portion 110 comprises an electrically insulating substrate and includes a first insulator 131 that serves to provide sufficient electrical insulation between first conductive surface 121 and third conductive surface 123. Similarly, second portion comprises an electrically insulating substrate and includes a second insulator 132 that serves to provide sufficient electrical insulation between second conductive surface 122 and fourth conductive surface 124.

[0080] The first insulator 131 can define one or more tracks, which are grooves for electrically insulating corresponding conductive surfaces disposed within the grooves. The tracks may have sidewalls, which not only improve electrical insulation but also serve to accommodate a flexible conductive band disposed within the track. In other words, as the flexible conductive band moves along a predetermined path (i.e., as the second portion 120 moves relative to the first portion 110), the flexible conductive band is constrained by the two corresponding conductive surfaces and the sidewalls of the tracks.

[0081] The insulator 131 and the second insulator 132 may each include at least one protrusion 140. If protrusions 140 are present in the electrical interface 100, both insulators may have the protrusions 140, or only one of the insulators may have the protrusions 140.

[0082] One or more protrusions 140 on the insulators 131, 132 are configured to interact with corresponding notches 170 on the flexible conductive bands 150, 160. As a result of this interaction, the flexible conductive bands 150, 160 can more easily be pulled into a rotational motion as the first portion 110 moves relative to the second portion 120. This can improve the electrical connection between the first portion 110 and the second portion 120 and also reduce the amount of friction between the flexible conductive bands and each of the first and second portions 110, 120.

[0083] However, it is noted that protrusions 140 are not required to provide rotational movement, which occurs regardless of whether or not there is a protrusion engaging a corresponding flexible conductive band.

[0084] The protrusions 140 help to provide spacing between adjacent flexible conductive bands. However, as noted above, the notches and protrusions 170, 140 can be omitted. This is one option when there is a single flexible conductive band 150 connecting the first conductive surface 121 to the second conductive surface 122. In this embodiment, omitting the notches and protrusions results in a device that is easier to manufacture, as there is no risk of the two bands contacting each other when a single flexible conductive band is used to transfer power.

[0085] In operation, a first voltage (V+) can be applied to first input terminal 530 and a second voltage (V−) can be applied to second input terminal 535. As a result, first conductive surface 121 is connected to the first voltage and third conductive surface 123 is connected to the second voltage.

[0086] The first and second voltages may each be a DC voltage or an AC voltage. While the two signals may be galvanically isolated from one another (as may be the case when two different unipolar signals are transmitted through electrical interface 100), the second voltage may also provide a return path for the first voltage (i.e., the first input voltage and the second input voltage are each part of a bipolar signal). In other words, the second voltage is a reference point (e.g., electrical ground or other voltage reference point), and current flows from the first input terminal 530 to the second input terminal 535 (or vice versa). This may be the case when electrical interface 100 is implemented in a motor, where current flows into the motor through the first input terminal 530 and out of the motor through the second input terminal 535.

[0087] In this example, first conductive surface 121 and third conductive surface 123 are annular (or ring-shaped). First and third conductive surfaces 121, 123 have similar dimensions and are attached to stationary first portion 110. Second conductive surface 122 and fourth conductive surface 124 are also annular. Second and fourth conductive surfaces 122, 124 have similar dimensions and are each attached to rotating second portion 120.

[0088] The diameters of the second and fourth conductive surfaces 122, 124 may be smaller than the respective diameters of the first and third conductive surfaces 121, 123. Similarly, the second portion 120 may be smaller in size than the first portion 110. As a result, the second portion 120 may be configured to fit within the larger first portion 110. In this case, the first conductive surface 121 may be aligned with the second conductive surface 122 in a direction along the longitudinal axis of the electrical interface 100, and the at least one flexible conductive band 150 may be configured to transmit electrical signals radially from the first conductive surface 121. The same alignment may be achieved for the third and fourth conductive surfaces 123, 124 and the corresponding at least one second flexible conductive band 160.

[0089] As a result of the flexible conductive bands 150, 160 of the electrical interface 100, the first conductive surface 121 remains in contact with the second conductive surface 122 while the second portion is rotating relative to the first portion 110. Similarly, the third conductive surface 123 remains in contact with the fourth conductive surface 124 while the second portion 120 is rotating relative to the first portion 110.

[0090] While the second portion 120 is rotating, both the plurality of flexible conductive bands 150 and the plurality of second flexible conductive bands 160 are configured to rotate around the first conductive surface 121 and the third conductive surface 123 of the first portion 110, respectively. Such rotational motion ensures that a low-friction electrical connection is always provided between the stationary first portion 110 and the rotating second portion 120.

[0091] The electrical interface 100 of the present invention can thus provide a means for transmitting power and electrical signals from the fixed member 510 to the rotating member 520. The electrical interface 100 of the present invention can therefore be considered an improved slip ring assembly, offering high current carrying capacity, high wear resistance, and low friction, all of which make the electrical interface 100 particularly advantageous for transmitting electrical signals to an electric motor assembly.

[0092] Of course, it should be understood that the electrical interface 100 of the present invention is not limited to motor designs, but may be used as a replacement for a typical brushed slip ring assembly wherever power needs to be transferred from a stationary structure to a rotating structure.

[0093] 1A and 1B, the electrical signals present on the second and fourth conductive surfaces 122, 124 can be communicated to other electrical hardware that may be attached to (or otherwise coupled to) the second portion. In some embodiments, this electrical hardware may be the electrical circuitry 550 of the motor.

[0094] In one example, conductive paths exist for communicating signals on second conductive surface 122 and signals on fourth conductive surface 124 to electrical hardware connected to second portion 120 of electrical interface 100. The electrical hardware may be attached to second portion 120 or indirectly coupled to second portion 120. Such electrical connections to the electrical hardware may be any suitable type of conductive path (e.g., wires, metal vias, traces, and / or via holes on a printed circuit board).

[0095] These connections can be made to the second and fourth conductive surfaces 122, 124, respectively, on the underside of the second and fourth conductive surfaces 122, 124 (i.e., on the side of the conductive surface opposite to the side that the flexible conductive band contacts), and do not interfere with the flexible conductive bands 150, 160.

[0096] In this manner, the first input voltage (V+) and the second input voltage (V-) supplied to the first portion 110 of the electrical interface 100 can be transmitted to the rotating second portion 120 and used to power the electrical circuit 550.

[0097] 3A and 3B show an embodiment of an electric motor according to the present invention, which includes an electrical interface 100 having a structure similar to that of the electrical interface 100 described above, and therefore the electrical interface 100 will not be described in further detail.

[0098] In this embodiment, the electric motor includes an electric circuit 550 and a plurality of conductive windings. The electric circuit 550 may be attached directly to the second portion 120 of the electrical interface 100. An output of the electric circuit may be connected to the plurality of conductive windings, and an input of the electric circuit 550 may be connected to a first voltage (V+) and a second voltage (V−).

[0099] At the output of the electrical interface 100, there may be conductive paths for communicating the signals on the second conductive surface 122 and the fourth conductive surface 124 of the electrical interface to an electrical circuit 550 that is connected to the second portion 120 of the electrical interface 100. Such connections may be any suitable type of conductive path (e.g., wires on a printed circuit board, metal vias, traces, and / or via holes). These connections may be connected to the underside of the second and fourth conductive surfaces (i.e., the conductive surfaces opposite the sides that are contacted by the flexible conductive bands) so as not to interfere with the flexible conductive bands.

[0100] Such electric motors also include a plurality of permanent magnets (not shown), and the interaction of current flowing through the plurality of conductive windings with the magnetic field generated by the plurality of permanent magnets can generate sufficient torque to rotate the motor when current is applied to the plurality of conductive windings.

[0101] The electrical circuit 550 may be an electronic drive circuit configured to be powered by first and second voltages (V+, V−) and to generate and communicate drive signals to the plurality of conductive windings to operate the motor.

[0102] In some embodiments, the first and second voltages input to the electrical interface 100 may be DC signals. In other words, the electric motor is a DC motor (a DC signal is input to the motor), and the motor electrical circuitry 550 is configured to generate an appropriate drive signal within the motor to operate the motor.

[0103] In some embodiments, the plurality of conductive windings includes armature coils of a three-phase motor. In such applications, the electronic drive circuit is configured to generate three-phase drive signals for three armature coils of the three-phase motor.

[0104] However, applications are not limited in this respect, and any number of phases may be implemented. If the motor has multiple phases (two or more), the number of armature coils corresponds to the number of phases present in the drive signal generated by the electronic drive circuitry. For example, if the motor has four armature phase windings, a four-phase signal may be generated by the electronic drive circuitry to communicate the appropriate signal to the appropriate armature coils.

[0105] In other words, the electronic drive circuitry is configured to generate a signal in each of a number of windings (forming part of the rotor) so that the flow of current is appropriate to interact with the permanent magnetic field present in the rotor, thereby generating torque.

[0106] The electronic drive circuitry can be configured to receive one or more signals from a sensor assembly (not shown) present within the motor, for example, the sensor assembly can include a position sensor configured to generate a relative or absolute position signal, and the electronic drive circuitry can utilize the position sensor to generate drive signals to each winding at the appropriate times.

[0107] The more armature phase windings present in an electric motor, the less detent cogging (also known as armature cogging) there is, resulting in smoother overall motor operation. This is particularly useful and desirable in applications where the motor must impart minimal vibration to the device it is connected to (e.g., servo motors where the motor is rigidly attached to the device's structure).

[0108] 4A and 4B show another embodiment of the present invention.

[0109] This embodiment operates in much the same manner as above, with the following differences: As above, electrical signals present on first conductive surface 121 are configured to communicate to second conductive surface 122 via at least one flexible conductive band. Similarly, electrical signals present on third conductive surface 123 are configured to communicate to fourth conductive surface 124 via at least one second flexible conductive band 160. As with the above embodiment, conductive surfaces 121, 122, 123, and 124 are all annular, but have different dimensions to allow for proper communication of electrical signals.

[0110] However, in this alternative embodiment, the second and fourth conductive surfaces 122, 124 are attached to the proximal face of the second portion 120. At least one flexible conductive band 150 and at least one second conductive band 160 connect the second and fourth conductive surfaces 122, 124 to the first and third conductive surfaces 121, 123 attached to the first portion 110 and are configured to transmit current in a direction parallel to the longitudinal axis of the electrical interface 100. That is, the first and third conductive surfaces 121, 123 are disposed proximal to the second and fourth conductive surfaces 122, 124, respectively. In other words, the first conductive surface 121 is configured to face the second conductive surface 122 in a direction defined by the longitudinal axis. Similarly for the third and fourth conductive surfaces 123, 124.

[0111] In this embodiment, first conductive surface 121 may have dimensions corresponding to second conductive surface 122. Third conductive surface 123 may have dimensions corresponding to fourth conductive surface. "Corresponding" may be understood to refer to an arrangement in which the dimensions are identical (i.e., the first conductive surface has the same shape and size as the second conductive surface). However, first and second conductive surfaces 121, 122 may have different dimensions than third and fourth conductive surfaces 123, 124.

[0112] In other words, the electrical signal (e.g., V+) present on the first and second conductive surfaces 121, 122 can be inside the electrical interface 100, and the electrical signal (e.g., V-) present on the third and fourth conductive surfaces 123, 124 can be outside the electrical interface 100.

[0113] As a result of the flexible conductive bands 150, 160 of the electrical interface 1, the first conductive surface 121 remains in contact with the second conductive surface 122 while the second portion 120 is rotating relative to the first portion 110. Similarly, the third conductive surface 123 remains in contact with the fourth conductive surface 124 while the second portion 120 is rotating relative to the first portion 110.

[0114] While second portion 120 rotates, both plurality of flexible conductive bands 150 and plurality of second flexible conductive bands 160 move in a rolling manner around first conductive surface 121 of first portion 110. Flexible conductive bands 150, 160 are also configured to rotate so that such rolling occurs. In other words, points along the outer edge of the flexible conductive bands in this embodiment move a greater distance than corresponding points along the band's inner edge. This rotational motion consistently provides a low-friction electrical connection between stationary first portion 110 and rotating second portion 120.

[0115] The notches 170, protrusions 140, electrical insulators 131, 132, and tracks all serve similar functions as described above and will not be described in further detail, it being understood that the notches, protrusions, and electrical insulators may all be present in this embodiment.

[0116] 4A and 4B, electrical signals present on the second and fourth conductive surfaces 122, 124 of the second portion 120 can be communicated to other electrical hardware that may be attached to (or otherwise coupled to) the second portion. In some embodiments, this electrical hardware may be the electrical circuitry 550 of the motor.

[0117] In one example, conductive paths exist for communicating signals on second conductive surface 122 and signals on fourth conductive surface 124 to electrical hardware connected to a second portion of electrical interface 100. The electrical hardware may be attached to the second portion or indirectly coupled to the second portion. Such electrical connections to the electrical hardware may be any suitable type of conductive path (e.g., wires, metal vias, traces, and / or via holes on a printed circuit board).

[0118] These connections can be made to the second and fourth conductive surfaces 122, 124, respectively, on the underside of the second and fourth conductive surfaces (i.e., on the side of the conductive surface opposite to the side contacted by the flexible conductive bands 150, 160) and do not interfere with the flexible conductive bands.

[0119] In this manner, the first input voltage (V+) and second input voltage (V-) supplied to the first portion 110 of the electrical interface 100 are transmitted to the rotating second portion 120 and used to power electrical hardware (such as the motor electrical circuitry 550).

[0120] Although the above embodiment provides two electrical interfaces 100, it is understood that the application is not limited thereto. There may be only one electrical interface 100 (i.e., first and second conductive surfaces 121, 122), or there may be more (e.g., three or more) electrical interfaces 100 within the same device.

[0121] According to an embodiment, an electric motor implementing an alternative electrical interface is also provided. The electric motor's electronic drive circuitry 550 and additional motor hardware (i.e., multiple conductive windings, permanent magnet assembly, etc.) are identical to the components described with reference to Figures 3A and 3B and will not be described again here. It will be understood that an electric motor is provided that is identical to the motor described in connection with Figures 3A and 3B, but has a separate electrical interface 100 for communicating electrical signals from the first portion 110 to the second portion 120.

[0122] 5A and 5B are diagrams of exemplary flexible conductive bands 150, 160 for use in embodiments of the present invention.

[0123] As shown in these figures, the flexible conductive bands 150, 160 can include a plurality of notches 170 distributed around at least one edge of the flexible conductive bands 150, 160. In some cases, a first plurality of notches 170 can be present along a first edge of the flexible conductive bands 150, 160 and a second plurality of notches can be present along a second edge of the flexible conductive bands 150, 160.

[0124] These flexible conductive bands 150, 160 can be flexible metal foils, such as stainless steel, coated on at least one side. In some examples, this coating can be titanium nitride (which can be applied, for example, by vacuum deposition or sputtering). This coating provides a very low coefficient of friction, further improving long-term operation of the bands and tracks.

[0125] Alternatively, instead of metal foil, a high-performance polymer film material (KAPTON, a type of polyimide plastic film) can be used. TMAlternatively, polyimide films such as copper or PET (polyethylene terephthalate) can be used. These polymeric films have excellent flexibility and can be repeatedly bent and folded without breaking. The polyimide film can also be coated with a number of highly conductive coatings and finishes, such as graphene. Further coatings can then be applied by electroless plating or electroplating through ion deposition in solution. This allows for the application of metals such as copper chloride, copper sulfate, nickel, palladium, ruthenium, or other suitable metals in solution.

[0126] The process of applying multiple platings or coatings to flexible plastic substrates is well suited to mass-produced miniature motors, further reducing reliance on expensive metals currently used in such motors.

[0127] Coatings can also be applied to polymeric films using liquid-based nanosilver inks. These inks can be applied by inkjet printing or silkscreen or gravure printing methods. These printing methods use photocurable nanosilver oxide inks that instantly transform to a metallic state upon contact with polymers such as PET (polyethylene terephthalate) through surface reduction. This change from the oxide state to the metallic state (a moisture-assisted electron transformation) can be used to further apply electroless copper. This results in very low-cost conductive flexible bands or discs for use in the present invention.

[0128] FIG. 6 illustrates an embodiment of a linear electric motor 600 that implements the electrical interface 100 according to one embodiment of the present invention. As shown in FIG. 6, the motor may be a type of voice coil actuator (i.e., a non-commutated linear actuator). In this embodiment, the connection between the first and second conductive surfaces 121, 122 (and the third and fourth conductive surfaces 123, 124) is made via at least one flexible conductive band 150 and at least one second flexible conductive band 160. In this illustration, there are two flexible conductive bands 150 and two second flexible conductive bands 160, but this is not intended to be limiting. That is, the number of flexible conductive bands (and second flexible conductive bands) may be any integer greater than or equal to one.

[0129] Power transfer between the first and second conductive surfaces 121, 122 (and between the third and fourth conductive surfaces 123, 124) follows the same principles as the previously described rotary electrical interface 100 (one portion rotates relative to the other portion). Instead, in this embodiment, the second portion 120 is configured to move linearly longitudinally relative to the first portion 110, and the respective conductive portions extend longitudinally accordingly. The movement of the flexible conductive bands 150, 160 (i.e., the rotational movement of the insulators 131, 132 within their respective orbits to maintain electrical contact between the two conductive surfaces at all times) follows the same principles as described for the rotary embodiment. The second portion may be fixedly mounted on the longitudinally movable member 620.

[0130] In this linear motor 600, power is supplied by communicating a bipolar electrical signal to the input terminals of the motors 630, 635 on the fixed member 610. This signal can be either an AC waveform or a DC waveform, with a first input (V+) and a second input (V-).

[0131] The first input is connected to the first conductive surface 121 and is in constant electrical communication with the second conductive surface 122 (mounted to the longitudinally movable member 620 via at least one second flexible conductive band). Similarly, the second input is connected to the third conductive surface 123 and is in constant electrical communication with the fourth conductive surface (mounted to the longitudinally movable member 620 via at least one second flexible conductive band). In this manner, bipolar electrical signals can be sent to the longitudinally movable member without the need for wear-prone members such as brushes.

[0132] The longitudinally movable member 620 also includes at least one conductive winding (not shown) connecting the second conductive surface 122 to the fourth conductive surface 123. This connection results in current flow from the first input 630 to the second input 635. More specifically, when a power source (not shown) is applied, current flows to the second input 635. When the illustrated flexible conductive band 160 is attached to the motor's input terminals, current flows from the input terminals through the first conductive surface 121, the at least one flexible conductive band, the second conductive surface 122, the at least one conductive winding, the fourth conductive surface 124, the at least one second flexible conductive band 160, and the third conductive surface 123, and back to the input terminals.

[0133] As a result of the electrical connections, a current flows through at least one conductive winding present on the longitudinally movable member, which current interacts with the linear electric motor's permanent magnet assembly 650 to generate a force that moves the longitudinally movable member 620 of the linear motor either distally or proximally relative to the fixed member 610 (depending on the polarity of the signal applied to the input terminals).

[0134] The foregoing description has been presented with reference to presently disclosed embodiments of the invention. Those skilled in the art, familiar with the field and technology to which the invention pertains, will understand that modifications and variations of the described structure may be made without significantly departing from the principles, spirit, and scope of the invention. As those skilled in the art will appreciate, the drawings are not necessarily to scale, and any feature or combination of features described in any embodiment may be incorporated into any other embodiment, or combined with any other feature of the other embodiments, as appropriate. Accordingly, the foregoing description should not be read as relating solely to the exact structure described and illustrated in the accompanying drawings, but rather as consistent with and supporting the following claims, which have their fullest and fairest scope. [Explanation of symbols]

[0135] 100 Electrical Interface 110 First Part 120 Second Part 121 first conductive surface 122 second conductive surface 123 Third Conductive Surface 124 Fourth Conductive Surface 131 First Insulator 132 Second Insulator 140 Protrusion 150 Flexible Conductive Band 160 Flexible conductive band, second flexible conductive band 170 Cutout 510, 610 Fixing member 520 Rotating member 530, 630 First input terminal 535, 635 Second input terminal 550 Electrical Circuits 600 Linear Electric Motor 620 Vertically movable members 650 Permanent Magnet Assembly

Claims

1. an electrical interface, a first portion having a first conductive surface; a second portion having a second conductive surface; at least one flexible conductive band configured to transfer power between the first conductive surface and the second conductive surface; the second portion is configured to move relative to the first portion; the at least one flexible conductive band is disposed between the first conductive surface and the second conductive surface; an electrical interface, wherein the at least one flexible conductive band is configured to maintain electrical contact between the first conductive surface and the second conductive surface at all times as the second portion moves relative to the first portion.

2. 10. The electrical interface of claim 1, wherein the at least one flexible conductive band is configured to mechanically interact with the first portion at a first contact area and to mechanically interact with the second portion at a second contact area such that when the second portion moves relative to the first portion, the flexible conductive band is configured to travel a predetermined path along the first conductive surface.

3. The electrical interface of claim 2 , wherein the at least one flexible conductive band is configured to move in a rolling motion to traverse the predetermined path.

4. the first portion includes a first insulator; the second portion includes a second insulator; the first conductive surface is mounted on the first insulator; 10. An electrical interface according to any one of the preceding claims, wherein the second conductive surface is mounted on the second insulator.

5. 5. The electrical interface of claim 4, wherein the first conductive surface is disposed within a track of the first insulator and the second conductive surface is disposed within a track of the second insulator.

6. When dependent on claim 2, the first insulator, the second insulator, or both the first and second insulators include at least one protrusion; 6. The electrical interface of claim 4 or 5, wherein the at least one conductive band includes at least one notch configured to interact with the at least one protrusion as the at least one flexible conductive band travels along the predetermined path.

7. the first insulator, the second insulator, or both the first and second insulators include a plurality of protrusions; 7. The electrical interface of claim 6, wherein the at least one conductive band includes a plurality of notches configured to interact with the plurality of protrusions as the at least one flexible conductive band travels along the predetermined path.

8. 10. An electrical interface according to any one of the preceding claims, wherein the at least one flexible conductive band comprises a plurality of flexible conductive bands.

9. 10. The electrical interface of claim 1, wherein the at least one flexible conductive band comprises a flexible polymeric substrate having a conductive coating, optionally the flexible polymeric substrate comprising polyimide.

10. The electrical interface of any one of claims 1 to 8, wherein the at least one flexible conductive band comprises a flexible metal substrate, optionally the flexible metal substrate comprises an amorphous metal.

11. 11. The electrical interface of claim 10, wherein the at least one flexible conductive band is formed by welding at least one of the flexible metal substrates to a continuous loop of conductive material, and optionally the flexible conductive band is braided in a welding operation to form a welded joint having interdigitated portions.

12. 10. An electrical interface according to any one of the preceding claims, wherein the at least one flexible conductive band comprises a thin film conductive coating.

13. the first portion is annular; the second portion is cyclic; 10. An electrical interface according to any one of the preceding claims, wherein the second portion is configured to rotate relative to the first portion.

14. the first annular portion has a first central axis passing through a center of the first annular portion in a direction transverse to the plane of the first annular portion; the second annular portion has a second central axis passing through a center of the second annular portion in a direction transverse to the plane of the second annular portion; the first central axis is aligned with the second central axis; The electrical interface of claim 13 , wherein the flexible conductive band is configured to rotate about the central axis to travel the predetermined path.

15. 15. The electrical interface of claim 14, wherein the first annular portion and the second annular portion have different outer diameters and are concentrically arranged with respect to one another such that electrical power flows between the first conductor and the second conductor toward or away from the central axis.

16. 15. The electrical interface of claim 14, wherein the first annular portion and the second annular portion have essentially the same diameter and are spaced a predetermined distance from the central axis such that power flows between the first conductor and the second conductor along the central axis.

17. the first portion further includes a third conductive surface; the second portion further includes a fourth conductive surface; the electrical interface further includes at least one second flexible conductive band that transmits electrical power between the third conductive surface and the fourth conductive surface; the at least one second flexible conductive band is disposed between the third conductive surface and the fourth conductive surface; 10. The electrical interface of claim 1, wherein the at least one second flexible conductive band is configured to maintain electrical contact between the third conductive surface and the fourth conductive surface at all times as the second portion moves relative to the first portion.

18. 20. The electrical interface of claim 17, wherein the at least one second flexible conductive band comprises a plurality of second flexible conductive bands.

19. An electric motor, A fixing member; a rotatable member configured to rotate relative to the fixed member; an electrical interface according to any one of the preceding claims, The fixing member is an input terminal configured to receive the power; The rotatable member comprises: a plurality of conductive windings; The electrical interface has the first portion electrically connected to the input terminal; the electrical interface electrically couples the second portion to the plurality of conductive windings; The electrical interface is configured to transfer the power from the input terminals to the plurality of conductive windings.

20. When claim 17 is dependent, the motor is a linear motor; the rotatable member further includes an electrical circuit connected to the plurality of conductive windings and configured to generate a motor drive signal for each of the plurality of conductive windings based on received electrical power; the at least one flexible conductive band and / or the at least one second conductive band are configured to transmit the power to the electrical circuit; 20. The electric motor of claim 19, wherein the electrical circuit is driven by the electrical power.

21. 1. A linear electric motor, comprising: A fixing member; a longitudinally movable member configured to move relative to the fixed member; An electrical interface according to any one of claims 1 to 12, the fixed member includes an input terminal configured to receive the power; the longitudinally movable member includes at least one conductive winding; The electrical interface has the first portion electrically connected to the input terminal; the electrical interface electrically couples the second portion to the at least one conductive winding; The electrical interface is configured to transfer the power from the input terminals to the plurality of conductive windings.

22. When claim 17 is dependent, the linear electric motor is an uncommutated linear actuator; the stationary member further includes a permanent magnet assembly; the at least one flexible conductive band and / or the at least one second conductive band are configured to transfer electrical power to the at least one conductive winding on the longitudinally movable member; 22. The linear electric motor of claim 21 , wherein current flowing through the plurality of conductive windings due to applied power interacts with a permanent magnetic field generated by a permanent magnet assembly to generate a force for moving the longitudinally movable member.

23. A method for manufacturing an electrical interface according to any one of claims 1 to 18, comprising the steps of: forming the at least one flexible conductive band from a flexible polymeric or metallic substrate; the at least one flexible conductive band being disposed between and in electrical contact with the first conductive surface of the first portion and the second conductive surface of the second portion.

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