Loudspeaker and method

Abstract

The invention relates to a loud speaker and a method, wherein the loudspeaker (100) comprises a rolled actuator (101) having a wound film composite (102), wherein the film composite comprises a first layer and a second layer, each having or consisting of a dielectric elastomer; a first electrode arranged between the first layer and the second layer in direct contact with same; a second metal layer arranged between a first sub-layer of the first electrode and a second sub-layer of the first electrode and electrically conductively connected to same; a second electrode arranged on a side of the first layer facing away from the first electrode and in direct contact with the first layer; a third electrode arranged on a side of the second layer facing away from the first electrode and in direct contact with the second layer; and a first metal layer that is electrically conductively connected to the third electrode.

Description

[0001] Description

[0002] Loudspeakers and procedures

[0003] Various embodiments relate to a loudspeaker and a method for manufacturing a loudspeaker.

[0004] Loudspeakers can be implemented with electrodynamic drives, capacitive drives, or piezoelectric drives, with electrodynamically driven loudspeakers being the most common. However, electrodynamic loudspeakers have a comparatively low efficiency (e.g., less than 1%) due to the limited magnetic flux density in the air gap, the current-dependent force effect, etc., and a comparatively high mass due to the permanent magnets used. To achieve radiation at a large angle using electrodynamic loudspeakers, it is necessary to provide different electrodynamic drives and radiating surfaces of different sizes for different frequency ranges.

[0005] According to various embodiments, a loudspeaker and a method for producing a loudspeaker are provided, wherein the loudspeaker enables reproduction of acoustic signals over a comparatively wide frequency range (e.g. speech, music, etc.) at a large radiation angle. This is made possible, for example, by a film composite which, among other things, has a dielectric elastomer arranged between electrodes, being wound in such a way that the wound film composite expands both in the axial direction (also referred to as the longitudinal direction) and in the radial direction when a respective voltage is applied to the electrodes. This volume displacement in the axial direction and radial direction (also referred to as the transverse direction) can be used to generate acoustic signals.

[0006] The roller actuator, for example, can perform both the drive function and the elastic mounting function, and optionally also the function of the radiating surface. This clearly enables a higher degree of functional integration compared to conventional loudspeakers.

[0007] Furthermore, unlike electrodynamic loudspeakers, the loudspeaker does not require permanent magnets, allowing the loudspeaker to have a lower mass than electrodynamic loudspeakers. This makes the loudspeaker advantageous for use where weight savings lead to (e.g., significant) cost reductions, such as in aerospace (e.g., in aircraft as loudspeakers for announcements by flight crew). Clearly, the loudspeaker described here can enable better spatial intelligibility (e.g., for announcements) compared to loudspeakers with an electrodynamic drive.

[0008] It shows

[0009] Figures 1A to 1H show a loudspeaker according to various embodiments;

[0010] Figures 2A and 2B show a schematic representation of the operating principle of the loudspeaker according to various embodiments;

[0011] Figures 3A to 3C each show a loudspeaker according to different embodiments;

[0012] Figures 4A and 4B show a circuit for dynamically controlling a loudspeaker according to various embodiments;

[0013] Figure 5 is a flowchart of a method for manufacturing a loudspeaker according to various embodiments; and

[0014] Figure 6 shows a system for manufacturing a loudspeaker according to various embodiments.

[0015] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced.

[0016] For public announcements, such as in buses, trains, airplanes, at train stations, at airports, etc. and / or telephone conferences, it may be necessary to use loudspeakers that have a large radiation angle (i.e., a broad radiation pattern) over a comparatively wide frequency range, so that both people far away and people directly below or next to the loudspeaker can hear the announcement(s). Various embodiments relate to a loudspeaker and a method for producing the same that has a broad radiation pattern over a wide frequency range. Furthermore, the loudspeaker is lighter than conventional electrodynamic loudspeakers, so that fuel can be saved, for example, in buses, trains, and airplanes.

[0017] Various embodiments relate to a roller actuator which enables a full-circumference volume increase (also referred to as full-circumference volume expansion). It is understood that this full-circumference volume increase of the roller actuator, as described herein, can be accompanied by a volume-constant deformation of the elastomer. The roller actuator can have the shape of a cylinder or at least a cylinder-like shape. According to various embodiments, the roller actuator can have the shape of a hollow cylinder. The base area of ​​the (hollow) cylinder can be an ellipse (e.g. a circle). However, the cylinder can also have a spiral base area. The area enclosed by the spiral base area can be substantially elliptical (e.g. circular). The spiral base area can be displaced parallel (like a cylinder) along a straight line (e.g. a straight line perpendicular to the base area).In the event that the base area of ​​the cylinder is elliptical (e.g., circular), the roller actuator may have one or more layer stacks that run essentially concentrically to the outer surface of the cylinder. In the following, the roller actuator is described using a spiral base area as an example. It is understood that the roller actuator may also have an elliptical (e.g., circular) base area formed by one or more layer stacks, wherein the sequence, arrangement, and features of the layers described below (e.g., electrodes, metal layer(s), etc.) may also apply analogously to the layers of the roller actuator with an elliptical base area.

[0018] FIG. 1A shows a loudspeaker 100 according to various embodiments. The loudspeaker 100 may include a roller actuator 101. The roller actuator 101 may serve as a drive (in some aspects also referred to as an (electromechanical) driver) of the loudspeaker 100. The roller actuator 101 may be configured to convert electrical signals (e.g., applied voltages) into a mechanical movement (see, for example, FIG. 2A and FIG. 2B and the associated description). FIG. 1B shows an exemplary top view of the roller actuator 101. The roller actuator 101 may include or be formed by a wound foil composite 102. The roller actuator 101 (e.g., the wound foil composite 102) may be elongated in an axial direction (e.g., z-direction). As used herein, “axially elongated” can be understood to mean that the length of the roller actuator in the axial direction is at least twice (e.g., at least three times, e.g., at least four times, etc.)) is greater than perpendicular to the axial direction. The direction perpendicular to the axial direction can also be referred to as the radial direction (e.g., x-direction). Illustratively, a height, h, of the roller actuator 101 can be at least twice greater than the width, b, of the roller actuator 101. Alternatively, the length of the roller actuator in the axial direction can also be smaller than the width of the roller actuator 101 (perpendicular to the axial direction).

[0019] The wound foil composite 102 can be arranged spirally around the longitudinal axis L (e.g., parallel to the z-axis) (e.g., as a planar Archimedean spiral). According to various embodiments, the wound foil composite 102 can be arranged in multiple windings (e.g., at least two windings, e.g., at least five windings, e.g., at least ten windings, etc.) around the longitudinal axis L. Each winding of the multiple windings can at least partially contact the subsequent winding of the foil composite 102. It is understood that two consecutive windings can be spaced apart from each other in individual regions. For example, air can be present between the consecutive windings in these regions.

[0020] The foil composite 102 can have a thickness, t, in each winding (see, for example, FIG. 1C). Therefore, the wound foil composite 102 can have a spiral base (e.g., in the xy plane) (see, for example, FIG. 1B). This spiral base can be displaced parallel along the axial direction, z, so that each cross-section of the wound foil composite 102 parallel to the xy plane has a spiral cross-sectional area that is substantially equal to the spiral base. Illustratively, the wound foil composite 102 can have the shape of a cylinder with a spiral base (in some aspects also referred to as a spiral cylinder).

[0021] The wound film composite 102 can at least partially enclose a cavity 104. For example, the wound film composite 102 can completely enclose the cavity 104 around the longitudinal axis L. Illustratively, a region enclosed by the wound film composite 102 can form a cavity. Illustratively, the wound film composite 102 can have the shape of a hollow cylinder with a spiral base area. The spiral base area can (e.g. be a flat Archimedean spiral and) have an (e.g. minimum) inner diameter, di, and an (e.g. maximum) outer diameter, da. The inner diameter, di, of the spiral base area can define a size of the cavity 104. According to various embodiments, the outer diameter, da, can be at least 1.3 times (e.g. at least 1.5 times, e.g. at least twice) as large as the inner diameter, di. If the ratio of outer diameter, da, to inner diameter, di, is greater than 1.3 (e.g.B. greater than or equal to two (e.g. greater than three, e.g. greater than four, e.g. greater than five, etc.)), this can enable the amplitude and / or the structural resonance required for sound radiation perpendicular to the axial direction of the roller actuator (see, for example, the description of FIG. 2B). This ratio can, for example, ensure that the roller actuator 101 (in some aspects also referred to as actuator) does not collapse under axial load (even due to its own mass inertia in resonance) and thus a force can be generated on a connected structure (e.g. the cover caps described herein, the vibrating body (e.g. the loudspeaker membrane) of the loudspeaker 300, etc.). Due to this area transformation (transfer of the movement to a larger area to achieve the necessary sound flow), the radiation behavior of low frequencies can be improved, among other things.This diameter ratio can be crucial for the usability of the axial direction (i.e., radiation in the axial direction), provided the cylinder is not axially preloaded (e.g., by internal or external springs), which, however, can lead to a significant increase in the lowest usable frequency. Due to the compliance mismatch of the actuator material, the axial resonance does not change with respect to the diameter ratio. However, this can be a critical factor for the radial amplitude and / or the frequency. The cavity 104 can optionally be filled with a dielectric material. In the exemplary cross-section shown in FIG. 1B, the innermost winding of the spiral encloses a substantially circular region, which forms the cavity 104. It is understood that the innermost winding of the spiral can enclose any type of elliptical region (with the circular region as a special case).For example, in this case, each winding of the spiral can be similar to the shape of an ellipse (with an offset resulting from the spiral character).

[0022] According to various embodiments, the movement of the roller actuator can be characterized by structurally dynamic resonances in the axial and radial directions (deflections). Depending on the adjusted ratios of the actuator dimensions, the structure, and the structural extensions (e.g., surfaces or surface ratios), these can be such that acoustically effective sound flows / sound pressures can be generated. The ratios can be designed so that one component, axial or radial, is dominant for sound generation, or the regions preferably overlap structurally. This provides, for example, the possibility of specifically influencing the frequency response and the radiation characteristics.

[0023] With reference to FIG. 1C, the film composite 102 may include a substrate film 106 (referred to as film 106 in some aspects). The substrate film 106 may include a first layer 108(1) and a second layer 108(2). The first layer 108(1) and the second layer 108(2) may each include or consist of a dielectric elastomer (e.g., the same dielectric elastomer). The dielectric elastomer may include, for example, an acrylate, a silicone, and / or a polyurethane. According to various embodiments, the dielectric elastomer may consist of a silicone, which has lower viscous behavior compared to the other materials (creep is thus reduced). Furthermore, the silicone may be resistant to environmental influences, such as ultraviolet (UV) radiation, and may have higher heat resistance (e.g., for silicone kitchen utensils).The aging process of silicones can also be significantly slower compared to acrylates and / or polyurethanes, so that the properties remain unchanged over a longer period of time or change less over a longer period of time.

[0024] Examples of dielectric elastomer materials are Danfoss-Polypower, Elastosil® and NEXIPAL®. Examples of dielectric elastomer materials are: silicone (Nusil, CF 19-2186), silicone (Nusil, CF 19-2186), silicone (Dow Coming, HS3), silicone (Dow Corning, Sylgard 186), silicone (Burman, Cine-Skin ArBrC), silicone (BJB, TC-5005), silicone (Dow Corning, Sylgard 184), silicone (Wacker Elastosil RT 625), silicone (BlueStar, MF620U), fluorosilicone (Dow Coming 730), fluoroelastomer (Lauren L143HC), PU (Deerfield PT6100S), NR latex, HNBR (Zetpol 3310, ACN content 25%), NBR, acrylic (3M VHB 4910), SEBS 75 (GLS Corp), SEBS 217 (GLS Corp), SEBS (Elastoteknik AB Dryflex 500040), SEBS-g-MA(Kraton), IPN (VHB 4905-TMPTMA), IPN (VHB 4910-TMPTMA), PTBA, Sylgard 184 5:1, Sylgard 184, Sylgard 184 15:1, Sylgard 184 20:1, Sylgard 186 5:1, Sylgard 186, a mixture of Sylgard 184 and Sylgard 186 (where different degrees of crosslinking are possible), Sylgard MIX 1:3, Sylgard MIX 1:1,Sylgard MIX 3 : 1, Ecoflex 00-50, Eco MIX 00-50 1 : 3, Eco MIX 00- 50 1 : 1, Eco MIX 00-50 3 : 1, Ecoflex 00-30, Eco MIX 00-30 1 : 3, Eco MIX 00-30 1 : 1, Eco MIX 00-30 3 : 1, Ecoflex 00-10, Eco MIX 00-10 1 : 3, Eco MIX 00-10 1 : 1, Eco MIX 00-10 3 : 1.,

[0025] The substrate film 106 may further include a first electrode 110(1), 110(2). The first electrode 110(1), 110(2) may be disposed between the first layer 108(1) and the second layer 108(2). The first electrode 110(1), 110(2) may be disposed in direct (e.g., physical and / or electrical) contact with the first layer 108(1) and the second layer 108(2). In one example, the first layer 108(1) may be coated with an electrode layer (e.g., 110(1)) and the second layer 108(2) may be coated with an electrode layer (e.g., 110(2)), and the two electrode layers may physically and electrically contact each other. In another example, the second layer 108(2), the first electrode 110(1), 110(2), and the first layer 108(1) may be formed as a layer stack. As described herein, the first electrode may consist of a single electrode layer or may alternatively consist of two sublayers (e.g.,formed by folding the first electrode layer 110).

[0026] The substrate film 106 may include a second electrode 112(1). The second electrode 112(1) may be arranged on a side of the first layer 108(1) facing away from the first electrode 110(1), 110(2). The second electrode 112(1) may be arranged in direct (e.g., physical and / or electrical) contact with the first layer 108(1).

[0027] The substrate foil 106 may include a third electrode 112(2). The third electrode 112(2) may be arranged on a side of the second layer 108(2) facing away from the first electrode 110(1), 110(2). The third electrode 112(2) may be arranged in direct (e.g., physical and / or electrical) contact with the second layer 108(2). In the event that the roller actuator does not include a metal layer or metal foil, the second electrode 112(1) and the third electrode 112(2), which are adjacent to each other and physically contact each other, may be formed from one layer.

[0028] The first electrode 110(1), 110(2), the second electrode 112(1), and the third electrode 112(2) may comprise or consist of an electrically conductive material. For example, the first electrode 110(1), 110(2), the second electrode 112(1), and / or the third electrode 112(2) may each comprise or consist of silver, or comprise or consist of silicone with soot particles, or comprise or consist of silicone with carbon nanotubes, or comprise or consist of silicone with graphene particles, or comprise or consist of silicone with silver nanowires, or comprise or consist of silicone coated with a metal layer (e.g., comprising or consisting of iron, copper, nickel, etc.). According to various embodiments, the first electrode 110(1), 110(2), the second electrode 112(1) and the third electrode 112(2) may be made of a material (e.g.a material arrangement) that is stretchable within the scope of the expansion of the wound foil composite 102 (see description of FIG. 2A and FIG. 2B) (e.g., comprising or consisting of one or more metals, carbon nanotubes, etc.). This stretchability of the electrodes can, for example, be inherent in the material and / or can be created by means of structuring.

[0029] According to various embodiments, the thickness of the first layer 108(1) and / or the thickness of the second layer 108(2) may be in a range from approximately 5 pm to approximately 500 pm (eg, in a range from approximately 50 pm to approximately 120 pm).

[0030] In one example, the first layer 108(1) and the second layer 108(2) may be made entirely or substantially entirely of a silicone and have a thickness of approximately 80 μm. For example, the first electrode 110(1), 110(2), the second electrode 112(1), and the third electrode 112(2) may each be made entirely or substantially entirely of silver, which may, for example, have a thickness of approximately 110 nm.

[0031] In another example, the dielectric elastomer may be Elastosil® and may have a thickness in a range of approximately 50 μm to approximately 100 μm. For example, the first electrode 110(1), 110(2), the second electrode 112(1), and the third electrode 112(2) may each comprise silicone containing carbon black particles and may each have a thickness in a range of approximately 20 μm to approximately 40 μm.

[0032] Optionally, the film composite 102 can further comprise a metal layer. The metal layer is described below, by way of example, as metal foil 114. It is understood that the metal foil is an exemplary metal layer and that the metal layer can also be any other type of metallic layer, such as a metallic layer produced by physical and / or chemical vapor deposition, by dip coating, by spraying, etc.

[0033] The metal foil 114 may comprise or consist of a metal or a metal alloy. The metal or metal alloy may have an electrical conductivity greater than or equal to 30 • 10 6S / m (Siemens per meter). The metal foil 114 can be made of aluminum or an aluminum alloy, for example. According to various embodiments, the thickness of the metal foil 114 can be less than half the thickness of the foil composite. This can reduce (e.g., prevent) separation of the individual foil layers of the wound foil composite, whereby stability and functionality of the roller actuator 101 can be ensured. For example, the first layer 108(1) and the second layer 108(2) can be made of Elastosil® with a thickness of approximately 100 μm, and the first electrode, the second electrode, and the third electrode can have a thickness of approximately 20 μm. In this example, the thickness of the metal foil 114 can be less than approximately 60 μm. In another example, the first layer 108(1) and the second layer 108(2) can be made of a silicone (e.g.,Danfoss Polypower) with a thickness of approximately 80 pm, and the first electrode, the second electrode, and the third electrode may have a thickness of approximately 100 nm. In this example, the thickness of the metal foil 114 may be less than approximately 60 pm.

[0034] The first electrode 110(1), 110(2), the second electrode 112(1) and the third electrode 112(2) may, for example, each be made of silver, which may, for example, have a thickness of approximately 110 nm.

[0035] In another example, the dielectric elastomer may be Elastosil® and may have a thickness in a range of approximately 50 μm to approximately 100 μm. For example, the first electrode 110(1), 110(2), the second electrode 112(1), and the third electrode 112(2) may each comprise silicone containing carbon black particles and may each have a thickness in a range of approximately 20 μm to approximately 40 μm.

[0036] In one example, the metal foil 114 may be an approximately 12 μm thick aluminum foil. An aluminum foil, for example, is advantageous because it has an electrical conductivity greater than 30 • 10 6 S / m and a comparatively low weight (e.g., compared to other metal foils). This comparatively low weight can, for example, improve the vibration behavior of the roller actuator 101. The passivation layer (oxide layer) of the aluminum foil can also provide high corrosion resistance.

[0037] The metal foil 114 may be electrically conductively connected to the substrate foil 106. For example, the metal foil 114 may be electrically conductively connected to the third electrode 112(2) (or alternatively, the second electrode 112(1)). The metal foil 114 may be in direct physical contact with the respective layer to provide the electrical contact or may be electrically conductively connected to the respective layer (e.g., the substrate foil 106 or the third electrode 112(2)) by means of one or more other layers (e.g., a carbon layer). For example, the metal foil 114 and the third electrode 112(112) may at least partially physically contact each other. As used herein, "at least partial" physical contact between two elements may be understood to mean that the two elements physically contact each other in at least one area (e.g., multiple areas).For example, several regions of the substrate foil 106 may directly contact the metal foil 114 and several other regions of the substrate foil 106 may be arranged at a (eg, air-filled) distance (eg, a few pm or less than 1pm) from the metal foil 114.

[0038] The metal foil 114 can reduce the contact resistance between the third electrode 112(2) of one winding and the second electrode 112(1) of the preceding winding. The reduced contact resistance can ensure that the cutoff frequency is greater than the desired maximum frequency of the loudspeaker 100.

[0039] It is understood that when the film composite 102 includes the metal foil 114, the thickness, t, of the film composite 102 may substantially correspond to the summed thickness of the substrate foil 106 and the metal foil 114, and that when the film composite 102 does not include the metal foil 114, the thickness, t, of the film composite 102 may substantially correspond to the thickness of the substrate foil 106.

[0040] According to various embodiments, the wound film composite 102 can be subjected to mechanical stress. Illustratively, a mechanical stress can act on the wound film composite 102. The mechanical stress can arise, for example, from the winding process. To illustrate, the film composite 102 can be wound under tension, and this tension can induce the mechanical stress acting on the wound film composite 102. The mechanical stress can lead to elongation (e.g., in the axial direction and / or radial direction) of the film composite 102. According to various embodiments, the elongation (also referred to as stretching) induced by the mechanical stress can be less than 50% (e.g., less than 20%; according to various embodiments, less than 10%).Illustratively, the size (in the axial direction and / or radial direction) of the stretched film composite 102 can be less than 1.5 times that of the non-stretched film composite 102 (i.e., if no mechanical stress were to act on the film composite 102). According to various embodiments, this comparatively small stretching can ensure that the roller actuator 101 can generate both a change in size in the axial direction and a change in size in the radial direction upon actuation (see description of FIG. 2A and FIG. 2B). Illustratively, a change in size in the axial direction and in the radial direction can be referred to as a full-circumference increase in volume. By means of the ratio of the stretching in the axial direction and the stretching in the radial direction, for example, the ratio of the proportion of axial radiation to the proportion of radial radiation (see description of FIG. 2A and FIG.2B), which allows, for example, the frequency range that can be generated to be modified. According to various embodiments, pre-stretching in the axial direction can be achieved by mechanically pre-stretching the roller actuator 101 during installation.

[0041] If the foil composite 102 is wound in such a way that the foil composite 102 in one winding physically contacts the foil composite in the next winding, the number of windings, N, can be determined according to N = da dl .

[0042] The windings of the film composite 102 can be glued together. In this case, an adhesive can be arranged between the successive windings. The adhesive can be, for example, an electrically conductive adhesive. The adhesive can have a thickness, k. In this case, the number of windings, N, can be determined according to n = da dl. It is understood that the thickness, k, for the innermost winding k and the outermost winding are to be subtracted respectively.

[0043] According to various embodiments, the metal foil 114 may be a first metal foil 114(1). With reference to FIG. 1D, the foil composite 102 may further comprise a second metal foil 114(2). The second metal layer 114(2) may be arranged between a first sub-layer 110(1) of the first electrode 110(1), 110(2) and a second sub-layer 110(2) of the first electrode 110(1), 110(2) and be electrically conductively connected thereto. Alternatively, the first electrode may comprise either the first sub-layer 110(1) or the second sub-layer 110(2). In this case, the second metal foil 114(2) may be arranged in direct contact with the respective sub-layer and the first or second layer. The second metal foil 114(2) can be configured as described above for the metal foil 114 (i.e., the first metal foil 114(1) in this example). In this case, the first metal foil 114(1) and the second metal foil 114(2) can be configured identically (e.g.,The first electrodes 110(1), 110(2), the second electrode 112(1), and the third electrode 112(2) may be different from one another (e.g., having the same material, the same thickness, etc.) or may be configured differently from one another. According to various embodiments, the first electrode 110(1), 110(2), the second electrode 112(1), and the third electrode 112(2) may completely cover the respective layer 108(1), 108(2). Alternatively, with reference to FIG. 1E, the first layer 108(1) and the second layer 108(2) may be free from the first electrode 110(1), 110(2), the second electrode 112(1), and / or the third electrode 112(2) in a first edge region 120 and / or a second edge region 122. Illustratively, for example, the first electrode 110(1), 110(2) may cover the first layer 108(1) and the second layer 108(2) only in a central region.Accordingly, for example, the second electrode 112(1) may cover the first layer 108(1) only in the central region and / or the third electrode 112(2) may cover the second layer 108(2) only in the central region. Consequently, the first edge region and / or the second edge region may be electrically insulating.

[0044] The edge regions 120, 122 can, for example, reduce (e.g., prevent) an acoustic short circuit (e.g., due to pressure equalization from the inside to the outside). The edge regions 120, 122 can, for example, prevent an electrical short circuit due to ionized air. According to various embodiments, the edge regions can be used as waveguides. Due to the extension of the sound path, positive interference with the radiated sound from the other side can occur when the sound exits.

[0045] According to various embodiments, the windings of the film composite 102 can be bonded together by adhesive in the first edge region 120 and / or the second edge region 122. According to various embodiments, the layers (e.g., films) of the film composite in the first edge region 120 and / or the second edge region 122 can be directly crosslinked to one another (e.g., by vulcanization).

[0046] The thickness of the first electrode 110(1), 110(2) may substantially correspond to the summed thickness of the second electrode 112(1) and the third electrode 112(2).

[0047] According to various embodiments, the elastic modulus of the dielectric elastomer of the first layer 108(1) and / or the second layer 108(2) may be in a range from approximately 100 kPa to approximately 10 MPa. For example, the dielectric elastomer may have an elastic modulus (E-modulus) of approximately 1 MPa. According to various embodiments, the film composite 102 (optionally in conjunction with the metal foil 114) may have an effective E-modulus (an E-modulus proportionally averaged over the respective volume of the layers / films) in a range from approximately 100 kPa to approximately 10 MPa.

[0048] With reference to FIG. 1F, the loudspeaker 100 can have a first cover cap 124 and a second cover cap 126. The first cover cap 124 can, for example, be placed on (and optionally fastened to) a first end face (e.g., base surface) of the roller actuator 101, and the second cover cap 126 can be placed on a second end face (e.g., the top surface) of the roller actuator 101. For example, the first cover cap 124 can cover the first end face and at least a portion of the second edge region 122, and the second cover cap 126 can cover the second end face and at least a portion of the first edge region 120. Illustratively, the first cover cap 124 and the second cover cap 126 can stabilize the wound foil composite 102.

[0049] The bonding and / or the cover caps 124, 126 can increase the rigidity of the roller actuator 101 and the usable bandwidth of the roller actuator 101, for example, because additional resonances can be utilized. The first cover cap 124 and the second cover cap 126 can, for example, generate additional structural resonances (e.g., of the caps) that can be used for mechanical and / or acoustic purposes.

[0050] According to various embodiments, the roller actuator 101 may have additional stiffening structures, such as one or more (e.g., helical) springs arranged in the cavity 104 and / or reinforcing / stiffening fibers wound with the foil composite 102 (and optionally the first metal foil 114(1) and / or the second metal foil 114(2)).

[0051] In an exemplary embodiment of the film composite 102, it can be designed without a metal foil 114. According to various embodiments of the film composite 102, a respective edge region of the first layer 108(1) and the second layer 108(2) can each be free of the first electrode 110(1), 110(2), the second electrode 112(1), or the third electrode 112(2). According to various embodiments, the first layer 108(1) and / or the second layer 108(2) can each have a structured surface in the normal direction (y or -y). A structured surface, as used herein, can be understood to mean that the surface has elevations and / or depressions in the normal direction. The structured surface can have a (e.g. regular) wave structure. The wave structure can, for example, reduce a respective strain of the first electrode 110(1), 110(2), the second electrode 112(1) and the third electrode 112(2) (e.g.The wave structure can, for example, create an anisotropy with respect to the surface expansion. Clearly, the expansion of the film composite 102 can be modified by means of the surface structure, which in turn can lead to a modification of the radiation characteristics, as described herein.

[0052] According to various embodiments, the substrate film 106 of the wound film composite 102 can be folded. FIG. 1G shows an unfolded state 140 (e.g., as part of the manufacturing process before folding). In the unfolded state 140, the substrate film 106 (in this case also referred to as unfolded substrate film 107) can have a substrate layer 108 which has or consists of the dielectric elastomer. In the unfolded state 140, the substrate film 106 can further have a first electrode layer 110 arranged on a first side of the substrate layer 108. In the unfolded state 140, the substrate film 106 can further have a second electrode layer 112 arranged on a second side of the substrate layer 108 opposite the first side.

[0053] In the present example, the substrate film 106 may be folded in the center, as indicated by the fold line, F. It is understood that the substrate film 106 may also be folded differently. The fold line, F, may divide the substrate film 106 into a first portion 106(1) and a second portion 106(2). FIG. 1G further shows an exemplary folded state 142 of the substrate film 106 (e.g., produced by folding at the fold line F in the folding direction 138). The substrate film 106 may be folded such that the first electrode layer 110 arranged in the first portion 106(1) and the first electrode layer 110 arranged in the second portion 106(2) at least partially touch each other. As shown, the first electrode layer 110 arranged in the first section 106(1) and the first electrode layer 110 arranged in the second section 106(2) may form the first electrode 110(1), 110(2).The second electrode layer 112 arranged in the first section 106(1) can form the second electrode 112(1). The second electrode layer 112 arranged in the second section 106(2) can form the third electrode 112(2). It can be clearly seen that in the wound film composite 102, which has the folded substrate film 106, an electrical short circuit between the first electrode layer 110 and the second electrode layer 112 can be prevented. According to various embodiments, the first electrode layer 110 can be formed only over the first section 106(1) or the second section 106(2), wherein the first electrode layer 110 in this case also forms the first electrode 110(1), 110(2) after folding.According to various embodiments, the second electrode layer 112 may be formed only over the first portion 106(1) or the second portion 106(2), in which case the second electrode layer 112 forms the second electrode 112(1) or the third electrode 112(2) after folding. FIG. 1G further shows another exemplary folding state 144 of the substrate foil 106 (e.g., produced by folding along the fold line F in the folding direction 138), wherein the substrate foil 106 and the second metal foil 114(2) may be folded around.The substrate foil 106 can be folded around the second metal foil 114(2) such that the first electrode layer 110 arranged in the first section 106(1) at least partially touches a first side of the second metal foil 114(2) and that the first electrode layer 110 arranged in the second section 106(2) at least partially touches a second side of the second metal foil 114(2) opposite the first side. According to various embodiments, the first electrode layer 110 can be formed only over the first section 106(1) or the second section 106(2), in which case the respective section of the first electrode layer 110 touches the second metal foil 114(2) after folding.

[0054] As an alternative to the folded substrate film 106 described, the substrate film 106 can also consist of a first film and a second film, wherein the first electrode layer 110 can be arranged on the first side of the first film and on the first side of the second film, and wherein the first film and the second film are arranged one above the other such that the first electrode layer 110 arranged above the first side of the first film and the first electrode layer 110 arranged above the first side of the second film touch each other. As described above, the second electrode layer 112 can form either the second electrode 112(1) or the third electrode 112(2), wherein in this case the electrode arranged above the subsequent winding can, for example, form both electrodes.According to various embodiments, the second metal foil 114(2) may be arranged between the first foil and the second foil such that the first electrode layer contacts one side of the second metal foil 114(2).

[0055] With reference to FIG. 1H, the wound foil composite 102 can include the substrate foil 106, the first metal foil 114(1), and the second metal foil 114(2). Optionally, the wound foil composite 102 can include a plurality of first foil sections 150(m=1 to M) (where M can be any natural integer greater than or equal to "1") that electrically contact the first metal foil 114(1) and that extend out of the spiral-cylindrical shape. For example, a first foil section 150(m) can be arranged in each winding, n, of the N windings, such that the number of windings, N, can correspond to the number, M, of first foil sections 150(m=1 to M). This is exemplary, and the wound foil composite 102 can include any number, M, of first foil sections 150(m=1 to M). Each first foil section 150(m) of the plurality of first foil sections 150(m=l to M) may be electrically conductively connected to the first metal foil 114(1).Illustratively, the extended first foil sections 150(m=l to M) can serve to electrically contact the first metal foil 114(1). The plurality of first foil sections 150(m=l to M) can be arranged substantially parallel to one another so that they can be electrically contacted together (see FIG. 1H). The first metal foil 114(1) can be electrically conductively connected to the third electrode 112(2). Furthermore, the first metal foil 114(1) can be electrically conductively connected to the second electrode 112(1) of the subsequent winding. Consequently, the first metal foil 114(1) in the wound foil composite 102 can be electrically conductively connected to both the second electrode 112(1) and the third electrode 112(2). According to various embodiments, the second electrode 112(1) and the third electrode 112(2) (e.g., jointly) can therefore be electrically contacted by means of the first foil sections 150(m=1 to M).The first film sections 150 (m = l to M) can protrude in the axial direction (z) beyond the base surface of the wound film composite 102 and / or beyond the cover surface of the wound film composite 102.

[0056] According to various embodiments, each first foil section 150(m) can consist of two sections that are connected to each other at least at one end. For example, these two sections can enclose the first metal foil 114(1). For example, the first metal foil 114(1) can be arranged between the two sections. Illustratively, each of the first foil sections 150(m=l to M) can be guided around the first metal foil 114(1) like a hook. The first foil sections can be pressed (e.g., embossed) with the first metal foil in a structured manner.

[0057] According to various embodiments, the first foil sections 150(m=l to M) may be made of the same material as the first metal foil 114(1). According to various embodiments, the first foil sections 150(m=l to M) may be part of the first metal foil 114(1). For example, the first foil sections 150(m=l to M) may be monolithically bonded to the first metal foil 114(1).

[0058] According to various embodiments, the protruding ends of each first foil section 150(m) can be T-shaped. This can improve contacting of the ends. According to various embodiments, the wound foil composite 102 can have a plurality of second foil sections 152(m=1 to M) (where M can be any natural integer greater than or equal to "1"), which electrically contact the second metal foil 114(2) and which extend out of the spiral-cylindrical shape. For example, a second foil section 152(m) can be arranged in each winding, n, of the N windings, so that the number of windings, N, can correspond to the number, M, of second foil sections 152(m=1 to M). This is exemplary, and the wound foil composite 102 can have any number, M, of second foil sections 152(m=1 to M).Each second foil section 152(m) of the plurality of second foil sections 152(m=l to M) can be electrically conductively connected to the second metal foil 114(2). Illustratively, the extended second foil sections 152(m=l to M) can serve to electrically contact the second metal foil 114(2). According to various embodiments, the first foil sections can be extended on a first side (e.g., base surface or cover surface) of the roller actuator 101, and the second foil sections can be extended on a side opposite the first side (e.g., cover surface or base surface). This can simplify contacting the first and second foil sections.The arrangement of the second foil sections can be similar to the above-described arrangement of the first foil sections, and the connection of the second foil sections to the second metal foil can be configured as described above for the connection of the first foil sections to the first metal foil. According to various embodiments, the second metal foil 114(2) in the wound foil composite 102 can be electrically conductively connected to the first electrode 110(1), 110(2), so that the first electrode 110(1), 110(2) can be electrically contacted by means of the second foil sections 152(m=1 to M).

[0059] As described herein, the first metal foil 114(1) and the second metal foil 114(2) can reduce the contact resistance between the respective electrodes. Paralleling the electrodes and contacting them through the respective foil sections can further reduce the contact resistance. This can, for example, lead to a homogenization of the phase delays (signal delays) resulting from the low-pass filter (e.g., in a differential RC network).

[0060] The cutoff frequency, f g , results from f q = — - — . According to various embodiments, the cutoff frequency, f g , be greater than 20 kHz, where the cutoff frequency, f g , at the point furthest from the contact electrode is greater than the intended working frequency and where the cutoff frequency, f g, at least 1.2 times greater than the first axial resonance. This can be achieved according to various embodiments by using the foil sections described above.

[0061] In this case, the electrical resistance generated by a natural oxide layer (e.g., aluminum oxide in the case of an aluminum layer as the metal layer) and the contact resistance (e.g., due to low contact pressure due to elongation of less than 50% and / or surface roughness) can be reduced. According to various embodiments, the first metal foil 114(1) and / or the second metal foil 114(2) can be embedded as a foil grid (e.g., consisting of a graphite mixture) in the respective electrode layer (e.g., in the first section 106(1) and / or the second section 106(2)). As described herein, the metal foils are an exemplary configuration of metal layers. According to various embodiments, the respective electrode layer (e.g., in the first section 106(1) and / or the second section 106(2)) can be covered by the associated metal layer (e.g., coated with the metal layer).

[0062] FIG. 2A schematically shows the functional principle for a planar layer 206 made of a dielectric elastomer. A first electrode layer 208 can be arranged over a first side of the planar layer 206, and a second electrode layer 210 can be arranged over a side of the planar layer 206 opposite the first side. Figure 202 shows the structure in a state in which no voltages are applied to the first electrode layer 208 and the second electrode layer 210. Figure 204 shows the structure in a state in which a first voltage (e.g., "+") is applied to the first electrode layer 208 and a second voltage different from the first voltage (e.g., "-") is applied to the second electrode layer 210. This can lead to an attraction between the first electrode layer 208 and the second electrode layer 210 (as shown by the filled arrows in FIG. 2A).This attraction between the first electrode layer 208 and the second electrode layer 210 can lead to an elastic deformation of the dielectric elastomer of the planar layer 206. This elastic deformation can lead to an expansion of the dielectric elastomer of the planar layer 206 in all directions parallel to the first electrode layer 208 and the second electrode layer 210 (as shown by the unfilled arrows in FIG. 2A). This can be a volume-invariant compressibility. It can be clearly seen that in this case, no expansion of the planar layer 206 perpendicular to the first electrode layer 208 and the second electrode layer 210 occurs, but rather the thickness of the planar layer 206 decreases. FIG. 2B schematically shows the functional principle for the roller actuator 101 of the loudspeaker 100 according to various embodiments.

[0063] The wound foil composite 102 can be arranged (e.g., wound) such that when a first voltage is applied to the first electrode 110(1), 110(2) and a second voltage different from the first voltage is applied to the second electrode 112(1) and the third electrode 112(2), the volume of the roller actuator 101 increases both in the axial direction (z-direction) (referred to as the axial direction in some aspects) and in the radial direction (in the x-direction and y-direction) (referred to as the radial direction in some aspects) (as shown by the unfilled arrows in FIG. 2G). Increasing the width can result in a larger circumference of the roller actuator 101. Illustratively, the volume of the roller actuator 101 can increase across its entire circumference when voltages are applied. According to various embodiments, the cavity 104 can enable the radial expansion of the roller actuator 101.

[0064] The magnitude of the first voltage and / or the second voltage can range from approximately 0.1 kV to approximately 10 kV. According to various embodiments, the roller actuator 101 can be operated at frequencies above the first fundamental resonance. For pressure chamber applications, the roller actuator 101 can also be used at frequencies below the fundamental resonance (although these frequencies can be shifted upwards depending on the design).

[0065] The total capacitance of the roller actuator can range from approximately 0.5 nF (nanofarads) to approximately 500 nF (e.g., approximately 5 nF to approximately 125 nF), depending on the dimensions, the number of windings, the materials used, etc. Larger ranges are also possible with appropriate dimensions.

[0066] According to various embodiments, the change in size in the radial direction and in the axial direction can be achieved by the elongation of the film composite 102 being less than 50%, as described herein. According to various embodiments, the first metal foil 114(1) and / or the second metal foil 114(2) can reduce the contact resistance to the respective electrodes, so that the loudspeaker 100 can achieve a high electrical cutoff frequency (e.g., greater than 20 kHz) despite the comparatively low elongation of the film composite 102 (and the resulting lower contact pressure of the windings of the film composite 102). The reduction in contact resistance can further improve (i.e., increase) the efficiency by reducing thermal losses. A reduction in actuator heating can increase the service life (including a lower risk of breakdown) of the roller actuator 101.

[0067] For example, the desired radial radiation of the loudspeaker 100 can be achieved by ensuring that the elongation of the film composite 102 in both the axial and radial directions is less than 50%, and by increasing the contact resistance of the metal foil 114. In another example, the metal foil 114 can be omitted, and the elongation of the film composite 102 in both the axial and radial directions can be less than 20% (e.g., less than 10%).

[0068] The (electrically) voltage-induced increase in width, b, can be increased, for example, by ensuring that the ratio of outer diameter, da, to inner diameter, di, of the wound foil composite 102 is greater than or equal to 1.3 (e.g., greater than 2). The voltage-induced increase in width, b, can be increased, for example, by using the first metal foil 114(1) and / or the second metal foil 114(2).

[0069] According to various embodiments, the magnification in the radial direction (i.e., in the radial direction) can be increased by increasing the number of windings (e.g., the number of layers).

[0070] The total volume increase (i.e., volume displacement acting in both the axial and radial directions) and the resulting force flow can be used to generate acoustic signals. The axial and radial magnifications occur in phase. Radiation occurs via displacement of the respective surfaces in modes that are constructively expressed (in phase) or act in separate frequency ranges.

[0071] The amplitude (e.g., the force acting upon volume displacement and / or the distance traveled by the volume displacement) can be substantially proportional to the applied voltage. According to various embodiments, the charge carriers stored in the capacitive arrangement as a result of applying a voltage can be recovered by means of recuperation. This can significantly increase the efficiency of the loudspeaker 100. This is not possible, for example, with electrodynamic drives, since in these the amplitude is proportional to the applied current. This clearly demonstrates the mode of operation of the roller actuator 101 and that it is suitable, for example, as a sound source drive. The roller actuator 101 does not require permanent magnets, so that, for example, no costs for rare earths (e.g., in the case of iron-neodymium-boron magnets) are incurred. The roller actuator 101 can be used as a sound-conducting element.The complete volume increase (i.e. the radial volume increase in addition to the axial volume increase) enables radiation at a significantly larger radiation angle compared to electrodynamic drives.

[0072] A loudspeaker with the roller actuator 101 described herein has several advantages over other loudspeakers (e.g., loudspeakers that use an electrodynamic drive):

[0073] - increased mechanical-acoustic coupling,

[0074] - a higher sound pressure level in a superimposed frequency range with the same electrical power supply,

[0075] - improved linearity (e.g. frequency response and / or distortion factor) in the superimposed frequency range (in connection with signal preprocessing),

[0076] - radiation in both axial and radial directions, whereby a homogeneous omnidirectional (e.g. hemispherical) radiation pattern is achieved,

[0077] - Energy can be recovered through recuperation,

[0078] - less electrical energy is required in low-frequency ranges,

[0079] - the roller actuator 101 can be used as a tweeter without any additional elements (e.g. surfaces of bodies),

[0080] - by means of the ratio of outer diameter to inner diameter and / or the mechanical stress acting on the film composite 102, the ratio of the proportion of axial radiation to the proportion of radial radiation can be adjusted, whereby, for example, the frequency range that can be generated can be extended.

[0081] According to various embodiments, a loudspeaker may comprise the roller actuator 101 and a vibratable body (referred to as a vibrating body in some aspects). The roller actuator 101 may be arranged at least partially above the vibratable body in the radiation direction of the loudspeaker. The expression “at least partially above” the vibratable body, as used herein, may be understood to mean that at least 50 percent (e.g., volume percent) of the roller actuator 101 is arranged above (i.e., above) the vibratable body in the radiation direction of the loudspeaker (which is perpendicular to the vibratable body). Thus, the roller actuator 101 may be translationally displaced with respect to the vibratable body along the tangential axis in the radiation direction such that at least 50 percent of the roller actuator 101 is arranged above the surface of the vibratable body.

[0082] For example, more than 90% of the roller actuator 101 can be arranged above the vibratable body in the beam direction of the loudspeaker. For example, the roller actuator 101 can be arranged entirely above the vibratable body.

[0083] Clearly, the roller actuator 101 can be arranged at least partially in the sound field of the loudspeaker 300.

[0084] The vibratable body can be any type of body that can vibrate in response to a force acting on it to generate sound waves. For example, the vibratable body can be a movably mounted body. The movably mounted body can have at least one radiating surface. The vibratable body can, for example, have or be a loudspeaker diaphragm, a vibrating plate (also called a vibratable plate), a vibrating disc, etc.

[0085] FIG. 3A, FIG. 3B, and FIG. 3C each show a loudspeaker 300 according to various embodiments. The loudspeaker 300 may include the roller actuator 101. The loudspeaker 300 may include a loudspeaker diaphragm 302. The loudspeaker 300 may have a (e.g., central) radiation direction 304. For example, the loudspeaker diaphragm 302 may be rotationally symmetrical with respect to the (central) radiation direction 304. According to various embodiments, the roller actuator 101 may be arranged at least partially (e.g., completely) above the loudspeaker diaphragm 302 in the radiation direction of the loudspeaker 300.

[0086] As shown in FIG. 3A, the speaker diaphragm 302 may have the shape of a cone (e.g., be conical). The speaker diaphragm 302 may have a concavely curved surface, and the roller actuator 101 may be arranged at least partially above the concavely curved surface in the radiation direction 304. For example, the speaker diaphragm 302 and the roller actuator 101 may be arranged in direct physical contact with each other.

[0087] With reference to FIG. 3B, the loudspeaker 300 can have a housing 306. The loudspeaker diaphragm 302 can be suspended from the housing 306 (e.g., movably). The roller actuator 101 can be arranged at least partially (e.g., completely) outside the housing 306. The full-circuit volume increase 308 of the roller actuator 101 can fully generate sound waves 310. Illustratively, a spherical radiation characteristic of the sound waves can be generated. The housing 306 can, for example, prevent an acoustic short circuit. An acoustic short circuit can be understood as the reduction of sound radiation from vibrating surfaces (e.g., the loudspeaker diaphragm 302) through direct pressure equalization between areas vibrating in antiphase. This can lead to at least partial cancellation of emitted sound waves.

[0088] With reference to FIG. 3C, according to various embodiments, the loudspeaker 300 may include a first vibratable body 302(1) and a second vibratable body 302(2). For example, a first side of the roller actuator 101 may be coupled to the first vibratable body 302(1), and a second side opposite the first side may be coupled to the second vibratable body 302(2). The first vibratable body 302(1) may have a first movable radiating surface A1. The second vibratable body 302(2) may have a second movable radiating surface A2. The vibratable body may, for example, be a loudspeaker diaphragm, a bending wave transducer, etc. The first vibratable body and the second vibratable body 302(2) may be the same type of vibratable body (e.g., each a loudspeaker diaphragm) or may be different types of vibratable bodies (e.g.,The first vibrating body can be a loudspeaker membrane and the second vibrating body can be a bending wave transducer, or vice versa. The first movable radiating surface A1 can have the same size as the second movable radiating surface A2, or the two surfaces A1, A2 can have different sizes. According to various embodiments, the sound radiation can take place in volume V3. Volume V1 and volume V2 can each be separated from volume V3 in such a way that no acoustic short circuit occurs. For example, connections such as bass reflex ports, waveguides, transmission lines, passive membranes, etc. are possible. According to various embodiments, volume V1 and volume V2 can be volumes of two separate rooms or can be part of a common room. For example, the two volumes V1, V2 can be connected to each other (e.g.by means of acoustic channels, resonators, acoustic masses, etc.). Volume VI and volume V2 can be the same size or can have different sizes (i.e., different volume values). This exemplary configuration can be used, for example, to modify the generable sound pressure level frequency response so that other (e.g., additional) resonances can be utilized.

[0089] It is understood that the roller actuator 101 can also be operated without additional surfaces (e.g., without the oscillating body). In this case, the inherent inertia of the roller actuator 101 may be sufficient. To better utilize the force in the axial direction, a fixation of the roller actuator 101, an inertial mass (a seismic mass), and / or a spring-supported bearing can be used. According to various embodiments, when mounted on a flexible plate or membrane, the inherent inertia of the free side may be sufficient as an inertial mass.

[0090] FIG. 4A and FIG. 4B each show an exemplary circuit 400 for (e.g., dynamically) controlling the roller actuator 101 (e.g., the loudspeaker 100 or the loudspeaker 300).

[0091] The circuit 400 may include a direct current (DC) supply 402. The circuit may include a relay 408 (referred to as a discharge resistor in some aspects). The relay 408 may be high-pulse capable. The circuit 400 may include a switch 404 connected between the direct current (DC) supply 402 and the relay 408. The circuit 400 may optionally include a light-emitting diode (LED) 406 (referred to as a status LED in some aspects) connected in parallel with the relay 408, which may indicate the status of the circuit 400 (e.g., ON or OFF). The switch 404 may

[0092] The circuit 400 may include a high-voltage alternating current (HV-AC) source 412. The high-voltage alternating current (HV-AC) source 412 may be, for example, a piezo amplifier. The circuit 400 may include a capacitor bank 414 coupled to the high-voltage alternating current (HV-AC) source 412. The capacitor bank 414 may include one or more capacitors. The circuit 400 may include a bleeder resistor 416. The circuit 400 may include a high-voltage direct current (HV-DC) source 422. The high-voltage direct current (HV-DC) source 422 may be limited to a current of 0.5 mA, for example. The circuit 400 may include a charging resistor 424 coupled to the high-voltage direct current (HV-DC) source 422. The circuit 400 may have a monitoring output 426. For example, a monitoring device may be connected to the monitoring output 426 to monitor the circuit 400.For example, the monitoring output 426 may provide selectable compensation for monitoring devices from a range of approximately 1 MQ to approximately 10 MQ.

[0093] The capacitor bank 414 can separate (e.g., isolate) the high-voltage alternating current (HV-AC) source 412 and the high-voltage direct current (HV-DC) source 422. The capacitance of the capacitor bank 414 can be several times (e.g., more than one hundred times) greater than the capacitance of the roller actuator 101.

[0094] Circuit 400 may include high-pulse-resistant line resistances. This may, for example, enable fast and safe discharging.

[0095] Driving the roller actuator 101 may require an adjustable polarization voltage, UDC, to enable bidirectional voltage-controlled movement. The capacitive and electrical low-pass characteristics of the roller actuator 101 may result in an increase in the required current with increasing frequency. For example, the circuit 400 may enable supplying comparatively high polarization voltages (e.g., in a range from approximately 0.1 kV to approximately 10 kV) and amplified signals with the required current (e.g., in a range from approximately 10 V to approximately 500 V, with currents up to several amperes, typically approximately 80 mA and 200 mA, respectively).

[0096] The circuit 400 may enable a substantially load-independent frequency response of the roller actuator 101. According to various embodiments, the circuit 400 may generate a bias voltage (referred to in some aspects as a bias voltage) of up to 10 kV and an output current greater than 100 mA.

[0097] As described above, the roller actuator 101 can also have an elliptical (e.g., circular) base formed by one or more layer stacks. In this case, the roller actuator can be manufactured, for example, by forming the layers of the one or more layer stacks one after the other from the inside out. A layer can be laminated, for example, or can be produced by dip coating (also referred to as candle pulling). For example, the electrode layers can be produced by dip coating, and the metal layer can be laminated as a metal foil.

[0098] In the following, a manufacturing process for winding a film composite is described as an example.

[0099] FIG. 5 shows a flowchart of a method 500 for manufacturing a loudspeaker according to various embodiments. FIG. 6 shows an exemplary system 600 for manufacturing the loudspeaker 100. For illustrative purposes, the method 500 will be described with reference to the system 600 for the loudspeaker 100. It is understood that the method 500 may also be performed by a differently configured system.

[0100] The system 600 may include a control device that may be configured to control the system 600 to execute the method 500. For this purpose, the control device may include one or more processors. The term "processor" may be understood as any type of entity that allows the processing of data or signals. The data or signals may, for example, be processed according to at least one (i.e., one or more than one) specific function performed by the processor. A processor may include or be formed from an analog circuit, a digital circuit, a mixed-signal circuit, a logic circuit, a microprocessor, a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a programmable gate array (FPGA), an integrated circuit, or any combination thereof.Any other type of implementation of the respective functions described in more detail below may also be understood as a processor or logic circuit. It is understood that one or more of the method steps described in detail herein may be executed (e.g., realized) by a processor, through one or more specific functions performed by the processor. The processor may therefore be configured to perform the method described herein.

[0101] The method 500 may include coating a first side of a film with a first electrode material (in 502). The film may include or consist of a dielectric elastomer. The method 500 may include coating a second side of the film opposite the first side with a second electrode material (in 504). The first electrode material and / or the second electrode material may, for example, be sprayed onto the film. Alternatively, the film may be coated with the first electrode material and / or the second electrode material by screen printing. Further alternatively, the first electrode material and / or the second electrode material may be vapor-deposited onto the film.

[0102] As described herein, a first edge region 120 and / or second edge region 124 of the foil can optionally be free of electrode material. For example, the first electrode material and / or the second electrode material can be deposited on the foil only in the region lying between the first edge region 120 and the second edge region 122. Alternatively, the first electrode material and / or the second electrode material can be removed after coating the foil in the first edge region 120 and / or the second edge region 122. The first electrode material and / or the second electrode material can be removed, for example, by etching (e.g., using nitric acid).

[0103] The method 500 may further comprise rolling a first end of the film onto a first roll 602 and a second end of the film onto a second roll 604 such that a central region of the film is not rolled onto either the first roll 602 or the second roll 604 (in 506). According to various embodiments, the first side of the film may be coated with the first electrode material before rolling. Alternatively, the first side of the film may be coated with the first electrode material after rolling (e.g., as part of the unrolling during rolling onto the fifth roll 610). Accordingly, the second side of the film may be coated before or after rolling. According to various embodiments, the film may also be coated during rolling.

[0104] The method 500 may further comprise folding the central region of the coated foil around a second metal foil 114(2) unwound from a third roll 606 such that the first electrode material disposed over a first portion of the foil contacts a first side of the second metal foil and that the first electrode material disposed over a second portion of the foil contacts a second side of the second metal foil opposite the first side (at 508). For example, the foil may be the substrate layer 108, which is coated with the first electrode material to form the first electrode layer 110 and which is coated with the second electrode material to form the second electrode layer 112. Subsequently, the foil (in this case, for example, the unfolded substrate foil 107) may be folded around the second metal foil 114(2) as shown in FIG. 1G and described with reference thereto (see Figure 144).

[0105] The method 500 may include bringing together (in 510) one side of the foil folded around the second metal foil 114(2) (e.g., substrate foil 106) and one side of a metal foil unwound from a fourth roll 608 (e.g., the first metal foil 114(1)) to form a foil composite (e.g., the foil composite 102).

[0106] Optionally, several additional rolls 606 can be used. The folded foil and the first metal foil 114(1) can be brought together in such a way that they are electrically conductively connected to one another.

[0107] The method 500 may include winding the foil composite (e.g., for producing the wound foil composite 102) onto a fifth roll 610 by unwinding the foil from the first roll 602 and the second roll 604, by unwinding the second metal foil 114(2) from the third roll 606, and by unwinding the first metal foil 114(1) from the fourth roll (in 512). The winding tension when winding the film composite onto the fifth roll 610 can be selected (e.g. depending on the material of the film composite and optionally the first metal foil 114(1) or the second metal foil 114(2)) such that an elongation of the wound film composite in the axial direction is less than 50% (e.g. less than 20%; according to various embodiments less than 10%) and / or that an elongation of the wound film composite in the radial direction is less than 50% (e.g. less than 20%; according to various embodiments less than 10%).

[0108] The method 500 makes it possible to wind the (e.g. non-stretchable) metal foil together with the stretchable folded foil (e.g. the stretchable substrate foil coated with electrode material) in such a way that reduced (e.g. essentially no) mechanical stresses occur between them in the (e.g. vertical) roll assembly.

[0109] Optionally, the method 500 may further comprise separating the wound film composite and the third roll 608. For example, the third roll 608 may be separable into at least two parts and may be removed from the interior of the wound film composite. Clearly, the removal of the third roll 608 may form the cavity 104. The wound film composite 102 with the cavity 104 may form the roller actuator 101. Optionally, the method 500 may further comprise arranging the roller actuator 101 on a vibratable body (e.g., the loudspeaker membrane 302 for producing the loudspeaker 300).

[0110] It is understood that aspects described with respect to the loudspeaker 100 or 300 may also be embodied as methods for manufacturing these configurations, and vice versa.

[0111] The loudspeaker 100, 300 described herein with the roller actuator 101 can be used, for example, in aerospace (e.g., in aircraft and / or at airports as a loudspeaker for announcements by aircraft crew), in local public transport (e.g., in buses and / or at bus stops as a loudspeaker for announcements), in the vicinity of a magnetic resonance imaging (MRI) scanner (e.g., as headphones that can be used in an MRI scanner), in museums, for building sound reinforcement, etc. Since the roller actuator 101, according to various embodiments, has no (ferromagnetic and / or ferroelectric) components, it can advantageously be used in the vicinity of MRI scanners. This also allows the weight of the loudspeaker to be significantly reduced, so that, for example, fuel can be saved in buses, trains, aircraft, etc. The loudspeaker described herein also places low demands on the required raw materials.According to various embodiments, the loudspeaker described herein may have a significantly higher efficiency compared to conventional loudspeakers (especially when power electronics with charge recuperation are used).

[0112] It is understood that the concept of full-surface volume increase (referred to in some aspects as volume expansion) described herein is described merely for illustrative purposes for the application as a loudspeaker, and that the roller actuator 101 is also suitable as an actuator for other applications, such as an actuator for a pump (e.g., a microfluidic pump), an actuator of a robot (e.g., in soft robotics), or other applications where a stress-induced full-surface volume increase is advantageous.

[0113] Examples are described below which illustrate embodiments of the concept of full volume increase.

[0114] Example 1 is a loudspeaker, comprising: a roller actuator having a wound foil composite, wherein the foil composite comprises: a first layer and a second layer, each comprising or consisting of a dielectric elastomer, a first electrode arranged between the first layer and the second layer in direct contact with these; a second metal layer arranged between a first sub-layer of the first electrode and a second sub-layer of the first electrode and electrically conductively connected to these; a second electrode arranged on a side of the first layer facing away from the first electrode and in direct contact with the first layer; a third electrode arranged on a side of the second layer facing away from the first electrode and in direct contact with the second layer; and a first metal layer (e.g.aluminum layer), which is electrically connected to the third electrode (e.g. by means of a carbon layer).

[0115] Example 2 is a loudspeaker comprising: a roller actuator comprising a wound foil composite, wherein the foil composite comprises a substrate foil and a first metal foil, wherein the substrate foil comprises: a first layer and a second layer, each comprising or consisting of a dielectric elastomer, a first electrode arranged between the first layer and the second layer in direct contact therewith, a second metal foil arranged between a first sub-layer of the first electrode and a second sub-layer of the first electrode and electrically conductively connected thereto;a second electrode arranged on a side of the first layer facing away from the first electrode and in direct contact with the first layer, and a third electrode arranged on a side of the second layer facing away from the first electrode and in direct contact with the second layer, wherein the substrate foil and the first metal foil are wound such that when a first electrical voltage is applied to the first electrode and a second electrical voltage different from the first electrical voltage is applied to the second electrode and the third electrode, a length of the roller actuator in the axial direction and a width of the roller actuator in the radial direction become larger.;

[0116] Example 3 is configured according to one of Examples 1 or 2, wherein a mechanical stress acting on the film composite induces an elongation of the film composite, wherein the elongation is less than 100% (e.g., less than 50%).

[0117] Example 4 is configured according to one of Examples 1 to 3, wherein the second metal layer is a second metal foil, and wherein the foil composite comprises a folded substrate foil, which in an unfolded state comprises: a substrate layer comprising or consisting of the dielectric elastomer, a first electrode layer arranged on a first side of the substrate layer and in direct contact with the substrate layer, and a second electrode layer arranged on a second side of the substrate layer opposite the first side and in direct contact with the second side of the substrate layer, wherein the substrate foil is folded in such a way (e.g., centrally) that the first electrode layer arranged on a first section (e.g., one half) of the substrate foil touches a first side of the second metal foil, and that the first electrode layer arranged on a second section (e.g.,the other half) of the substrate foil touches a second side of the second metal foil opposite the first side, so that: the first electrode layer forms the first electrode, the first section of the substrate foil forms the first layer, the second electrode layer arranged on the first section of the substrate foil forms the second electrode, the second section of the substrate foil forms the second layer, and the second electrode layer arranged on the second section of the substrate foil forms the third electrode.

[0118] Example 5 is configured according to any one of Examples 1 to 4, wherein the first metal layer (also referred to as metallic layer) is a first metal foil and / or wherein the second metal layer is a second metal foil.

[0119] Example 6 is configured according to one of Examples 1 to 5, wherein the wound foil composite has at least one first foil section in each winding, which is electrically conductively connected to the first metal layer and projects beyond one end of the first layer and the second layer in the axial direction of the roller actuator in such a way that the first metal layer in each winding of the wound foil composite can be electrically conductively contacted by means of the first foil sections; and / or wherein the wound foil composite has at least one second foil section in each winding, which is electrically conductively connected to the second metal layer and projects beyond one end of the first layer and the second layer in the axial direction of the roller actuator (e.g.an end opposite the first foil sections) in such a way that the second metal layer in each winding of the wound foil composite can be electrically conductively contacted by means of the second foil sections.

[0120] Example 7 is a loudspeaker according to examples 5 and 6, wherein the first metal foil has the first foil sections and / or wherein the second metal foil has the second foil sections.

[0121] Example 8 is configured according to Example 7, wherein the first metal foil and the first foil sections are formed from the same material and / or wherein the second metal foil and the second foil sections are formed from the same material.

[0122] Example 9 is a loudspeaker according to any one of examples 6 to 8, wherein the distances between two consecutive first film sections in a developed state of the wound film composite are substantially equal and / or wherein the distances between two consecutive second film sections in a developed state of the wound film composite are substantially equal.

[0123] Example 10 is configured according to any one of examples 6 to 9, wherein the first film sections are arranged substantially parallel to one another and / or wherein the second film sections are arranged substantially parallel to one another.

[0124] Example 11 is a loudspeaker according to any one of Examples 1 to 10, wherein the wound foil composite encloses a cavity.

[0125] Example 12 is configured according to any one of Examples 1 to 11, wherein the number of windings of the wound film composite is greater than or equal to two.

[0126] Example 13 is a loudspeaker comprising: a multi-layer, hollow-cylindrical roller actuator having one or more layer stacks arranged substantially concentrically to the outer surface of the roller actuator, wherein each of the one or more layer stacks comprises: a first layer and a second layer, each comprising or consisting of a dielectric elastomer; a second metal layer arranged between the first layer and the second layer; a first electrode layer arranged between the first layer and the second metal layer and in direct contact therewith; a fourth electrode layer arranged between the second layer and the second metal layer and in direct contact therewith; a second electrode layer arranged on a side of the first layer facing away from the first electrode layer and in direct contact with the first layer;a third electrode layer arranged on a side of the second layer facing away from the fourth electrode layer and in direct contact with the second layer; and a first metal layer (e.g., aluminum layer) electrically connected to the third electrode layer (e.g., by means of a carbon layer);

[0127] Example 14 is configured according to Example 13, wherein the respective metal layer of the one or more layer stacks is a metal foil. Example 15 is a loudspeaker according to either of Examples 13 and 14, wherein each of the one or more layer stacks further comprises at least one foil section that is electrically conductively connected to the metal layer and projects beyond an end of the first layer and the second layer in the axial direction of the roller actuator such that the respective metal layer of each layer stack can be electrically conductively contacted by means of the at least one foil section.

[0128] Example 16 is configured according to Examples 14 and 15, wherein the respective metal foil has the at least one foil section.

[0129] Example 17 is configured according to Example 16, wherein the respective metal foil and the at least one foil section are formed from the same material.

[0130] Example 18 is a loudspeaker according to any one of examples 15 to 17, wherein the roller actuator comprises the plurality of layer stacks and wherein the film sections are arranged substantially parallel to each other.

[0131] Example 19 is configured according to any one of Examples 1 to 18, wherein the respective metal layer comprises or consists of aluminum.

[0132] Example 20 is configured according to any one of Examples 1 to 19, wherein the electrical resistance of the respective metal layer is less than or equal to 30-10 6 S / m, and / or wherein the density of the respective metal layer is less than or equal to 3 g / cm 3 is

[0133] Example 21 is configured according to any one of Examples 1 to 20, wherein the metal layer has a thickness in a range of about 0.1 pm to about 100 pm (eg, about 12 pm).

[0134] Example 22 is a loudspeaker comprising: a vibratable body, a roller actuator comprising a wound foil, the foil comprising: a first layer and a second layer, each comprising or consisting of a dielectric elastomer; a first electrode arranged between the first layer and the second layer in direct contact therewith; a second electrode arranged on a side of the first layer facing away from the first electrode and in direct contact with the first layer; and a third electrode arranged on a side of the second layer facing away from the first electrode and in direct contact with the second layer; wherein the roller actuator is arranged at least partially above the vibratable body in the radiation direction of the loudspeaker.

[0135] Example 23 is configured according to Example 22, wherein the wound foil encloses a cavity.

[0136] Example 24 is a loudspeaker according to any one of examples 22 or 23, wherein the number of turns of the wound foil is greater than or equal to two.

[0137] Example 25 is configured according to any one of Examples 22 to 24, wherein the film comprises a folded substrate film, which in an unfolded state comprises: a substrate layer comprising or consisting of the dielectric elastomer, a first electrode layer arranged on a first side of the substrate layer and in direct contact with the substrate layer, and a second electrode layer arranged on a second side of the substrate layer opposite the first side and in direct contact with the second side of the substrate layer, wherein the substrate film is folded in such a way (e.g., centrally) that the first electrode layer arranged on a first section (e.g., one half) of the substrate film and the second electrode layer arranged on a second section (e.g.,the other half) of the substrate film, so that: the first electrode layer forms the third electrode, the first section of the substrate film forms the first layer, the second electrode layer arranged on the first section of the substrate film forms the second electrode, the second section of the substrate film forms the second layer, and the second electrode layer arranged on the second section of the substrate film forms the third electrode.

[0138] Example 26 is a loudspeaker comprising: a vibratable body, a multi-layer, hollow-cylindrical roller actuator comprising one or more layer stacks arranged substantially concentrically to the outer surface of the roller actuator, wherein each of the one or more layer stacks comprises: a first layer and a second layer, each comprising or consisting of a dielectric elastomer; a first electrode layer arranged between the first layer and the second layer in direct contact therewith; a second electrode layer arranged on a side of the first layer facing away from the first electrode layer and in direct contact with the first layer; and a third electrode layer arranged on a side of the second layer facing away from the first electrode layer and in direct contact with the second layer;wherein the roller actuator is arranged at least partially above the vibratable body in the beam direction of the loudspeaker;

[0139] Example 27 is configured according to any one of examples 22 to 26, wherein the vibratable body is a loudspeaker diaphragm.

[0140] In Example 28, the loudspeaker according to Example 27 may optionally further comprise: a loudspeaker housing, wherein the loudspeaker diaphragm is suspended (movably mounted) by means of the housing.

[0141] Example 29 is configured according to example 27 or 28, wherein the loudspeaker diaphragm has a concavely curved surface (e.g., is cone-shaped), wherein the roller actuator (in the radiation direction of the loudspeaker) is arranged on the concavely curved surface of the loudspeaker diaphragm (e.g., is arranged in direct contact with the concavely curved surface).

[0142] Example 30 is configured according to any one of Examples 1 to 29, wherein the dielectric elastomer comprises an acrylate, a silicone, natural rubber, or a polyurethane.

[0143] Example 31 is configured according to any one of Examples 1 to 30, wherein the dielectric elastomer has a modulus of elasticity between 100 kPa and 10 MPa (e.g., approximately 1 MPa), and / or wherein the film composite or the one or more layer stacks has / have an effective modulus of elasticity between 100 kPa and 10 MPa (e.g., approximately 1 MPa).

[0144] Example 32 is configured according to any one of Examples 1 to 31, wherein the ratio of (e.g., maximum) outer diameter of the roller actuator to (e.g., minimum) inner diameter of the roller actuator is greater than or equal to two.

[0145] Example 33 is configured according to any one of Examples 1 to 32, wherein the first electrode or first electrode layer, and / or the second electrode or second electrode layer, and / or the third electrode or third electrode layer comprises or consists of silver, silicone with soot particles, or silicone with carbon nanotubes, or silicone with graphene particles, or silicone with silver nanowires, or silicone coated with a metal layer (e.g. comprising iron, nickel, copper, etc.).

[0146] Example 34 is configured according to any one of Examples 1 to 33, wherein a thickness of the first electrode (e.g., in a range of approximately 200 nm to approximately 80 pm) corresponds to the summed thicknesses of the second electrode and the third electrode, or wherein the thickness of the first electrode layer corresponds to the summed thicknesses of the second electrode layer and the third electrode layer.

[0147] Example 35 is configured according to any one of Examples 1 to 34, wherein the side of the first layer contacting the first electrode, the side of the first layer contacting the second electrode, the side of the second layer contacting the first electrode, and / or the side of the second layer contacting the third electrode has a structured surface in the normal direction of the respective surface.

[0148] Example 36 is configured according to Example 35, wherein the structured surface has a (e.g., regular) wave structure.

[0149] Example 37 is a loudspeaker according to any one of examples 1 to 36, wherein the loudspeaker does not have a permanent magnet.

[0150] Example 38 is configured according to any one of Examples 1 to 37, wherein the loudspeaker does not include a permanent magnetic material. According to various embodiments, the loudspeaker may also not include a ferroelectric material.

[0151] Example 39 is configured according to any one of Examples 1 to 38, wherein an upper edge region and / or a lower edge region of the first layer is free of the first electrode and / or free of the second electrode, and / or wherein an upper edge region and / or a lower edge region of the second layer is free of the first electrode and / or free of the third electrode.

[0152] Example 40 is a pump comprising: a housing filled with gas and / or liquid, a roller actuator which is arranged in the gas and / or liquid and which has a wound foil composite, wherein the foil composite has: a first layer and a second layer, each comprising or consisting of a dielectric elastomer; a first electrode which is arranged between the first layer and the second layer in direct contact with them; a second metal foil which is arranged between a first sub-layer of the first electrode and a second sub-layer of the first electrode and is electrically conductively connected to them; a second electrode which is arranged on a side of the first layer facing away from the first electrode and in direct contact with the first layer;a third electrode arranged on a side of the second layer facing away from the first electrode and in direct contact with the second layer; and a first metal foil (e.g., aluminum foil) electrically connected to the third electrode.

[0153] Example 41 is a pump comprising: a housing filled with gas and / or liquid, a multi-layer, hollow cylindrical roller actuator arranged in the gas and / or liquid and having one or more layer stacks arranged substantially concentrically to the outer surface of the roller actuator, wherein each of the one or more layer stacks comprises: a first layer and a second layer, each comprising or consisting of a dielectric elastomer; a second metal layer arranged between the first layer and the second layer; a first electrode layer arranged between the first layer and the second metal layer in direct contact therewith; a fourth electrode layer arranged between the second layer and the second metal layer and in direct contact therewith;a second electrode layer arranged on a side of the first layer facing away from the first electrode layer and in direct contact with the first layer; a third electrode layer arranged on a side of the second layer facing away from the fourth electrode layer and in direct contact with the second layer; and a first metal layer (e.g., aluminum layer) electrically connected to the third electrode layer (e.g., by means of a carbon layer);

[0154] Example 42 is a method of manufacturing a loudspeaker (e.g., a loudspeaker according to any one of Examples 1 to 39), the method comprising: coating a first side of a foil with a first electrode material, wherein the foil comprises or consists of a dielectric elastomer; coating a second side of the foil opposite the first side with a second electrode material; rolling a first end of the foil onto a first roll and a second end of the foil onto a second roll such that a central region of the foil is not rolled onto either the first roll or the second roll; folding the central region of the coated foils around a second metal foil unwound from a third roll such that the first electrode material arranged on a first portion (e.g., one half) of the foil contacts a first side of the second metal foil, and the first electrode material arranged on a second portion (e.g.,the other half) of the foil touches a second side of the second metal foil opposite the first side; bringing together one side of the foil folded around the second metal foil and one side of a first metal foil (e.g. aluminum foil) unwound from a fourth roll to form a foil composite; and winding the foil composite onto a fifth roll by unwinding the foil from the first roll and the second roll, the second metal foil from the third roll and the first metal foil from the fourth roll such that the foil composite has an elongation of less than 50% in the wound state.

[0155] Example 43 is configured according to Example 42, wherein the folded foil and the first metal foil are brought together to form the foil composite such that the folded foil and the first metal foil are electrically conductively connected to one another.

[0156] Example 44 is a method according to Example 42 or 43, wherein coating the film with the first electrode material comprises spraying the first electrode material onto the film or coating the film by screen printing, and / or wherein coating the film with the second electrode material comprises spraying the second electrode material onto the film or coating the film by screen printing.

[0157] The coating of the foil with the first electrode material and / or the coating of the foil with the second electrode material may take place before the first end of the foil is rolled onto the first roll and the second end of the foil is rolled onto the second roll or may take place after this rolling.

[0158] Example 45 is configured according to any one of Examples 42 to 44, wherein the first electrode material corresponds to the second electrode material.

[0159] Example 46 is a method according to any one of Examples 42 to 45, further comprising: prior to folding the coated foils, removing (e.g., by etching) the first electrode material from an upper edge region and / or a lower edge region of the first side of the foil in the winding direction of the foil, and / or removing (e.g., by etching) the second electrode material from an upper edge region and / or a lower edge region of the second side of the foil in the winding direction of the foil.

[0160] Example 47 is a method according to any one of Examples 42 to 45, wherein coating the first side of the film comprises: coating the first side of the film with the first electrode material such that an upper edge region and / or a lower edge region of the first side of the film in the winding direction of the film is free of the first electrode material, and / or wherein coating the second side of the film comprises: coating the second side of the film with the second electrode material such that an upper edge region and / or a lower edge region of the second side of the film in the winding direction of the film is free of the second electrode material.

[0161] Example 48 is a method according to any one of Examples 42 to 47, further comprising: separating the wound film composite and the fifth roll (eg, such that the wound film composite encloses a cavity).

[0162] In Example 49, the method according to Example 48 may optionally further comprise: after separating the wound foil composite and the fifth roll, arranging the wound foil composite on a vibratable body (e.g. a loudspeaker membrane) in the radiation direction of the loudspeaker running perpendicular to the vibratable body.

[0163] Example 50 is a computer-readable medium (e.g., a computer program product, a non-transitory storage medium, a non-transitory storage medium, a non-volatile storage medium) capable of storing instructions that, when executed by a processor, cause the processor to control an apparatus to perform a method according to one or more of the forty-second example through the forty-ninth example.

Claims

Patent claims 1. Loudspeaker (100), comprising: a roller actuator (101) comprising a wound foil composite (102), wherein the foil composite (102) comprises: • a first layer (108(1)) and a second layer (108(2)), each comprising or consisting of a dielectric elastomer; • a first electrode (110(1), 110(2)) which is arranged between the first layer (108(1)) and the second layer (108(2)) in direct contact with them; • a second metal layer (114(2)) which is arranged between a first sub-layer (110(1)) of the first electrode (110(1), 110(2)) and a second sub-layer (110(2)) of the first electrode (110(1), 110(2)) and is electrically connected to them; • a second electrode (112(1)) which is located on the side of the first layer (108(1)) facing away from one of the first electrodes (110(1), 110(2)) and in direct contact with the first layer (108(1)); • a third electrode (112(2)) which is arranged on the side of the second layer (108(2)) facing away from one of the first electrodes (110(1), 110(2)) and in direct contact with the second layer (108(2)); and • a first metal layer (114(1)) which is electrically connected to the third electrode (112(2)).

2. Loudspeaker (100) according to claim 1, wherein a mechanical stress acting on the wound foil composite (102) induces a strain of the foil composite (102), wherein the strain is less than 50%.

3. Loudspeaker (100) according to one of claims 1 or 2, wherein the second metal layer (114(2)) is a metal foil and wherein the foil composite (102) comprises a folded substrate foil (106) which is in an unfolded state: • a substrate layer (108) comprising or consisting of the dielectric elastomer, • a first electrode layer (110) which is arranged on a first side of the substrate layer (108) and in direct contact with the substrate layer (108), and • a second electrode layer (112) arranged on a second side of the substrate layer (108) opposite the first side and in direct contact with the second side of the substrate layer (108); wherein the substrate film (106) is folded such that the first electrode layer (110(1)) arranged on a first section of the substrate film (106) contacts a first side of the metal foil and that the first electrode layer (110(2)) arranged on a second section of the substrate film (106) contacts a second side of the metal foil opposite the first side, such that: • the first electrode layer (110) forms the first electrode (110(1), 110(2)), • the substrate layer (108) in the first section of the substrate film (106) forms the first layer (108(1)), • the second electrode layer (112) arranged on the first section of the substrate film (106) forms the second electrode (112(1)), • the substrate layer (108) in the second section of the substrate film (106) forms the second layer (108(2)), and • the second electrode layer (112) arranged on the second section of the substrate film (106) forms the third electrode (112(2)).

4. Loudspeaker (100) according to one of claims 1 to 3, wherein the wound foil composite (102) has in each winding at least one first foil section (150) which is electrically conductively connected to the first metal layer (114(1)) and extends in the axial direction of the roller actuator (101) over a first end of the first layer (108(1)) and the second layer (108(2)) such that the first metal layer (114(1)) in each winding of the wound foil composite (102) can be electrically contacted by means of the first foil sections (150);and wherein the wound foil composite (102) has at least one second foil section (152) in each winding, which is electrically conductively connected to the second metal layer (114(2)) and extends in the axial direction of the roller actuator (101) over a second end of the first layer (108(1)) and the second layer (108(2)) opposite the first end, such that the second metal layer (114(2)) can be electrically contacted in each winding of the wound foil composite (102) by means of the second foil sections (152).

5. Loudspeaker (100) according to claim 4, wherein the first metal layer (114(1)) is a first metal foil and wherein the first metal foil has the first foil sections (150); and / or wherein the second metal layer (114(2)) is a second metal foil and wherein the second metal foil comprises the second foil sections (152). Loudspeaker (100) according to any one of claims 1 to 5, wherein the wound foil composite (102) encloses a cavity (104). Loudspeaker (100) according to any one of claims 1 to 6, wherein the electrical resistance of the first metal layer (114(1)) and / or the electrical resistance of the second metal layer (114(2)) is less than or equal to 30 × 10 6 S / m is; and / or wherein the density of the first metal layer (114(1)) and / or the density of the second metal layer (114(2)) is less than or equal to 3 g / cm³ 3is; wherein preferably the first metal layer (114(1)) and / or the second metal layer (114(2)) comprises or consists of aluminum. Loudspeaker (100) according to any one of claims 1 to 7, wherein the ratio of the outer diameter (da) of the roller actuator (101) to the inner diameter (di) of the roller actuator (101) is greater than or 1.

25. Loudspeaker (100) according to any one of claims 1 to 8, wherein • the side of the first layer (108(1)) contacting the first electrode (110(1), 110(2)), and / or • the side of the first layer (108(1)) contacting the second electrode (112(1)), and / or • the side of the second layer (108(2)) contacting the first electrode (110(1), 110(2)), and / or • the side of the second layer (108(2)) contacting the third electrode (112(2)) has a structured surface in the normal direction to the respective surface; wherein the structured surface preferably has a wave structure. Loudspeaker (100) according to any one of claims 1 to 9, wherein the loudspeaker (100) does not have a permanent magnetic material; and / or wherein the loudspeaker (100) does not have a ferroelectric material. Loudspeaker (100) according to any one of claims 1 to 10, wherein an upper edge region and / or a lower edge region of the first layer (108(1)) is free from the first electrode (110(1), 110(2)) and / or free from the second electrode (112(1)); and / or wherein an upper edge region and / or a lower edge region of the second layer (108(2)) is free from the first electrode (110(1), 110(2)) and / or free from the third electrode (112(2)). Loudspeaker (300) comprising: • a vibrating body (302); • a roller actuator (101) comprising a wound film, the film comprising: o a first layer (108(1)) and a second layer (108(2)), each comprising or consisting of a dielectric elastomer; o a first electrode (110(1), 110(2)) arranged between the first layer (108(1)) and the second layer (108(2)) in direct contact with them; o a second electrode (112(1)) arranged on the side of the first layer (108(1)) facing away from the first electrode (110(1), 110(2)) and in direct contact with the first layer (108(1)); and a third electrode (112(2)) which is located on the side of the second layer (108(2)) facing away from one of the first electrodes (110(1), 110(2)) and in direct contact with the second layer (108(2)); • wherein the roller actuator (101) is arranged at least partially above the vibrating body (302) in the direction of radiation (304) of the loudspeaker (300). Loudspeaker (300) according to claim 12, wherein the vibrating body (302) is a loudspeaker diaphragm; wherein preferably the loudspeaker diaphragm has a concavely curved surface and wherein the roller actuator (101) is arranged on the concavely curved surface of the loudspeaker diaphragm. Method (500) for manufacturing a loudspeaker, comprising the method (500): • Coating a first side of a film with a first electrode material, wherein the film comprises or consists of a dielectric elastomer (502); • Coating a second side of the foil opposite the first side with a second electrode material (504); • Rolling one end of the film onto a first roll and one end of the film onto a second roll such that a middle area of ​​the film is not rolled onto either the first roll or the second roll (506); • Folding the central area of ​​the coated foil around a second metal foil unwound from a third roll such that the first electrode material arranged on a first section of the foil touches a first side of the second metal foil and that the first electrode material arranged on a second section of the foil touches a second side of the second metal foil opposite the first side (508); • Combining one side of the foil folded around the second metal foil and one side of a first metal foil unwound from a fourth roll to form a foil composite (510); and • Winding the film composite onto a fifth roll by unwinding the film from the first roll and the second roll, the second metal foil from the third roll, and the first metal foil from the fourth roll, such that the film composite in the wound state has an elongation of less than 50% (512). Method (500) according to claim 14, further comprising: • Separating the wound film composite and the fifth roll, so that the wound film composite encloses a cavity; and • Arranging the wound foil composite on a vibrating body in the direction of radiation of the loudspeaker, perpendicular to the vibrating body.

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