Electrodynamic driver for a loudspeaker or acoustic transducer with improved damping

Abstract

The invention relates to an electric driver for a loudspeaker or acoustic transducer with improved damping. An electric driver for a plate-like structure or diaphragm is disclosed, the electric driver comprising a voice coil, a magnetic circuit system and a plurality of arms movably coupling the voice coil and the magnetic circuit system. The arms are made of a metal having a fatigue strength of at least 370 N / mm 2 or an ultimate tensile strength of at least 1100 N / mm 2 . Each of the arms comprises at least two arm sections arranged to be movable relative to each other and connected to each other by a damping material having a tensile storage modulus of 0.1 MPa - 6000 MPa and a tensile loss factor of at least 0.1, both measured at room temperature of 20°C. Furthermore, the invention relates to a loudspeaker and electric transducer having such an electric driver and to a method of manufacturing an intermediate product for such an electric driver.

Description

TECHNICAL FIELD

[0001] The present invention relates to an electrodynamic actuator designed to be connected to a backside of a plate-like structure or diaphragm opposite to a sound emanating surface of the plate-like structure or diaphragm and comprising at least one voice coil, a magnetic circuit system and an arm device having a plurality of arms. The voice coil has electric conductors in the shape of a loop extending in the loop portion around a voice coil axis, and the magnetic circuit system is designed to generate a magnetic field transverse to the conductors in the loop portion. The arm device couples the at least one voice coil and the magnetic circuit system and allows a relative movement between the voice coil and said magnetic circuit system in an excursion direction parallel to the voice coil axis. Alternatively, the arm device couples the at least one voice coil and a movable portion of the magnetic circuit system and allows a relative movement between the voice coil and said movable portion of the magnetic circuit system in an excursion direction parallel to the voice coil axis.

[0002] The present invention further relates to a loudspeaker comprising an electrodynamic actuator of the above-mentioned type and a diaphragm fixed to the at least one voice coil and the magnetic circuit system.

[0003] In addition, the present invention relates to an electrodynamic (acoustic) transducer comprising a plate-like structure having a sound emanating surface and a backside opposite to the sound emanating surface. The electrodynamic transducer further comprises an electrodynamic actuator of the above-mentioned type connected to the plate-like structure at said backside. In particular, the plate-like structure can be embodied as a display. In this way, the electrodynamic actuator forms together with the display an output device (for both audio and video data).

[0004] Finally, the present invention relates to a method of manufacturing an intermediate product for an electrodynamic actuator, wherein at least one voice coil and a magnetic circuit system of the above-mentioned type are provided and an arm device of the above-mentioned type is manufactured. Further, the at least one voice coil is coupled to the magnetic circuit system by using the arm device, thereby allowing a relative movement between the voice coil and said magnetic circuit system in an excursion direction parallel to the voice coil axis. Alternatively, the at least one voice coil is coupled to a movable portion of the magnetic circuit system by using the arm device, thereby allowing a relative movement between the voice coil and said movable portion of the magnetic circuit system in an excursion direction parallel to the voice coil axis. BACKGROUND

[0005] Electrodynamic actuators, loudspeakers, transducers and methods of the above-mentioned type are generally known. An electrical acoustic signal fed to the voice coil generates a force in the magnetic field of the magnetic circuit system and causes a movement between the voice coil device and the magnetic circuit system or at least a movable portion thereof. The diaphragm or plate-like structure is in turn deflected or moved in accordance with the electrical acoustic signal. Accordingly, a sound corresponding to the electrical acoustic signal emanates from the sound emanating surface of the plate-like structure or diaphragm.

[0006] The ever-increasing output power associated with the size of the electrodynamic exciter places considerable demands on the arm arrangement, since the high excursions associated with the size of the electrodynamic exciter induce considerable bending stresses in the arm of the arm arrangement. On the other hand, the arm should induce as low a mechanical resistance (i.e. the force that counteracts the force generated by the electroacoustic signal) as possible in order to maintain a high efficiency of the electrodynamic actuator. Metals and in particular high-strength metals are materials that in principle meet these requirements. Unfortunately, high-strength metals provide only low damping and almost no damping. As a result, unwanted vibrations may occur in the arm arrangement, which impair the acoustic properties of the loudspeaker or transducer and in particular the sound quality. This is particularly true at one or more resonant frequencies of the arm arrangement. It should be noted at this point that, even worse, these vibrations are not necessarily associated with high excursions of the sound-emitting surface, but the arm arrangement itself may vibrate, causing only small excursions of the sound-emitting surface. In short, this means that in very bad cases, the energy and sound quality are destroyed, essentially for no result. Summary of the Invention

[0007] It is therefore an object of the present invention to overcome the disadvantages of the prior art and to provide a better electrodynamic exciter, a better loudspeaker, a better electrodynamic transducer and a better method of manufacture. In particular, the damping of the arm arrangement should be improved while maintaining high output power and / or high efficiency.

[0008] The problem of the invention is solved by an electrodynamic exciter as defined in the opening paragraph, wherein

[0009] - The arm has a fatigue strength of at least 370N / mm 2 Or the ultimate tensile strength is at least 1100N / mm 2 of metal, and wherein,

[0010] - Each of the arms comprises at least two arm segments, which are arranged to be movable with respect to each other and are connected to each other by a damping material having a tensile storage modulus of 0.1 MPa to 6000 MPa and a tensile loss factor of at least 0.1, both measured at room temperature of 20°C.

[0011] Furthermore, the problem of the invention is solved by a loudspeaker comprising an electrodynamic exciter of the type described above and a diaphragm fixed to at least one voice coil and a magnetic circuit system.

[0012] Furthermore, the problem addressed by the present invention is solved by an electrodynamic transducer comprising a plate-like structure having a sound-emitting surface and a back surface opposite the sound-emitting surface, and an electrodynamic exciter of the aforementioned type connected to the back surface. Advantageously, at least one voice coil or magnetic circuit system of the electrodynamic exciter comprises a flat mounting surface intended for connection to the back surface of the plate-like structure opposite the sound-emitting surface, wherein the back surface is oriented perpendicular to the voice coil axis. In particular, the plate-like structure can be embodied as a display. Thus, the electrodynamic exciter and the display together form an output device (for both audio and video data).

[0013] The above-described measures significantly improve the damping of the arm arrangement while maintaining high output power and / or high efficiency. This is achieved through a special material mix of a strong, even high-strength metal and a relatively soft damping material. By connecting at least two arm sections that can move relative to each other, the amplitude of any oscillations can be significantly reduced compared to an arm arrangement without the proposed damping.

[0014] Thus, on the one hand, the arms can be made with a very small to tiny cross-section so as to cause as little mechanical resistance as possible (i.e., the force that counteracts the force generated by the electroacoustic signal), but on the other hand, unwanted vibrations are substantially suppressed. In other words, an arm made of very thin metal (metal foil) with the proposed damping has excellent properties in a given application and is superior to commonly used devices. Advantageously, the height of the cross-section of the arm is in the range of 10 μm to 100 μm. In addition, it is beneficial if the cross-sectional width of the arm and in particular the metal core is in the range of 200 μm to 800 μm. Despite their low thickness, these metals (metal foils) are very durable and, due to their low thickness, generate relatively low mechanical resistance. Thus, an electrodynamic transducer with the proposed technical features provides high output power while being small in size, highly efficient and having high sound quality.

[0015] Advantageously, the arms and in particular the metal core can be made of or comprise steel, brass, bronze, molybdenum or tungsten. It is advantageous if the arms are made of or comprise stainless steel, and it is very advantageous if the arms are made of, in particular, a metal with a fatigue strength of 370 N / mm 2 Up to 670N / mm 2 range or ultimate tensile strength is 1100N / mm 2 Up to 2000N / mm 2made of or comprising a cold-rolled stainless steel within the scope. Advantageously, an austenitic stainless steel can be used for the arm, in particular stainless steel 1.4404. Austenitic stainless steels have a high proportion of austenite and are therefore non-magnetic or low-magnetic. Thus, when the arm moves in a magnetic field in the magnetic gap of the magnetic circuit system, no or only a small (unwanted) force is introduced into the arm. Such a force would change the (dynamic) idle position of the moving coil and deteriorate the behavior of the moving coil. Furthermore, the austenitic stainless steel does not or substantially not magnetically bridge the magnetic gap of the magnetic circuit system. In other words, the arm does not form a magnetic short circuit in the magnetic circuit system. Furthermore, the stainless steel has the advantage of being oxidation-resistant in addition to the characteristics presented above.

[0016] The "fatigue strength" (or endurance limit or fatigue limit) is generally the stress level below which a material can be subjected to an infinite number of loading cycles without resulting in fatigue failure or unacceptable deformation. Above this stress level, fatigue failure or unacceptable deformation will occur at some point in time.

[0017] The "ultimate tensile strength" is the maximum stress a material can withstand while stretching or being pulled before breaking (in the case of a single load). By experience, the ultimate tensile strength is about three times the fatigue strength of a metal.

[0018] It should be noted that for the sake of simplicity, tensile stresses are mentioned and in fact a combination of shear, compression and elongation deformations can occur.

[0019] The use of a metal for the arm device has further advantages. Advantageously, at least some of the arms of the arm device can be electrically connected to at least one voice coil. Thus, the arms can provide the function of electrically connecting the voice coil with fixed terminals which in turn are used to connect the moving coil to further circuitry, for example to a power amplifier. There, the arms can pick up electro-acoustic signals and / or feedback signals which can be used to measure the behavior of the moving coil and further control the behavior of the moving coil.

[0020] In order to improve the electrical function of the arms, the metallic core of the arms can be coated with a metal having very good electrical conductivity. Beneficially, the at least one coating metal layer can comprise or consist of copper, silver, gold or aluminum.

[0021] Generally, it is advantageous if the coating structure comprises an outer coating made of a polymer (such as a thermoplastic, a thermoset, an elastomer, a silicone or a rubber) which at least partially (and in particular completely) covers the at least one arm.

[0022] In general, the storage modulus and loss modulus are related to the ratio of stress to strain of a viscoelastic material under vibration conditions. The storage modulus (usually denoted by the character E') is related to the stored energy, representing the elastic part of the viscoelastic material, and the loss modulus (usually denoted by the character E") is related to the energy dissipated as heat, representing the viscous part of the viscoelastic material. The ratio of the loss modulus to the storage modulus is defined as the loss factor, which can also be written as tanδ if the storage modulus E' is regarded as the real part of the complex modulus E* and the loss modulus E" is regarded as the imaginary part of the complex modulus E*, where δ is the angle between the complex modulus E* and the real part E'. Therefore, the complex modulus E* can be written as E*=E'+jE". In addition, it should be noted that δ is not only the angle between the complex modulus E* and the real part E', but also the phase lag between stress and strain.

[0023] In the definition of electrodynamic actuators, the tensile storage modulus and the tensile loss factor are used to define the material suitable for a given application. It should be noted that this is for simplification purposes, and in reality, combined deformations of shear, compression, and elongation may occur. Tensile storage moduli of 0.1 MPa to 6000 MPa are particularly relevant for plastics, and for example, silicone has a loss factor of approximately 0.1.

[0024] The proposed measures are particularly applicable to "micro" electrodynamic exciters. The proposed measures are also generally applicable to loudspeakers, in particular to loudspeakers with a diaphragm area of ​​less than 600 mm. 2 and / or the back cavity volume is 200mm 3 Up to 2cm 3 Micro speakers in the range of . Such micro speakers are used in all types of mobile devices, such as mobile phones, mobile music devices, laptops and / or headphones. It should be noted that at this time, the micro speaker does not necessarily include its own back volume, but can use the space of the device with the built-in speaker as the back volume. This means that the speaker does not necessarily include its own (closed) housing, but can only include an (open) frame. The back volume of a device with such a built-in speaker is usually less than 10cm 3 .

[0025] Furthermore, the diameter of the metal core of the electrical conductor of the at least one voice coil of the "micro" electrodynamic actuator is advantageously ≤ 110 μm. Depending on the circumstances, the electrical conductor may also comprise an (electrically insulating) coating on the metal core.

[0026] In general, an "electrodynamic actuator" converts electrical energy into movement and force. Together with the diaphragm, the electrodynamic actuator forms a "loudspeaker." Together with the panel, the electrodynamic actuator forms an "electrodynamic (acoustic) transducer." A specific embodiment of the panel is a display. In this case, the electrodynamic actuator and the display form an "output device" (for both audio and video data). In general, the loudspeaker, electrodynamic transducer, and output device convert electrical energy into sound.

[0027] It should be noted that sound can also be emitted from the back side of the plate-like structure and the diaphragm. However, this back side usually faces the interior space of a device (e.g., a mobile phone) that has a built-in speaker or output device. Therefore, the plate-like structure or diaphragm can be considered to have a primary sound-emitting surface and a secondary sound-emitting surface (i.e., the back side). The sound waves emitted by the primary sound-emitting surface reach the user's ears directly, while the sound waves emitted by the secondary sound-emitting surface do not reach the user's ears directly, but only reach the user's ears indirectly via reflection or excitation from other surfaces of the housing of the device that has a built-in speaker or output device.

[0028] In the context of this disclosure, a "movable portion of a magnetic system" refers to a portion of the magnetic system that is movable relative to at least one voice coil. Typically, the magnetic system may have a fixed portion and a movable portion, with the fixed portion being fixedly mounted to or relative to the voice coil. It is also possible that the entire magnetic system is movable relative to at least one voice coil. In this case, the movable portion of the magnetic system is the magnetic system, and there is no fixed portion.

[0029] The magnetic circuit system and / or the voice coil may be connected to or may be part of a housing or frame, and the arm may be connected to the housing or frame. Thus, the arm is not necessarily directly connected to the voice coil and the movable part of the magnetic circuit system, but may also be indirectly connected to the voice coil and the movable part of the magnetic circuit system.

[0030] An “arm arrangement” may also be considered and referred to as a “spring arrangement,” and an “arm” may be considered and referred to as a “(spring) leg.” In particular, in the case where the electrodynamic exciter is connected to the back of the plate-like structure, the arrangement of multiple arms may be considered as a spring arrangement, and in the case where the electrodynamic exciter is connected to the back of the diaphragm, the arrangement of multiple arms may be considered as a suspension system.

[0031] The term "coupled" in the above sense comprises both a direct connection between the at least one voice coil and the magnetic circuit system, in particular the movable part of the magnetic circuit system, via the arm means, and an indirect connection thereof via an intermediate part which is arranged fixedly with respect to the at least one voice coil or the magnetic circuit system, in particular with respect to the movable part of the magnetic circuit system. Such an intermediate part can be a frame to which the at least one voice coil or the magnetic circuit system, in particular the movable part of the magnetic circuit system, is attached.

[0032] Further advantageous embodiments are disclosed in the claims and the description and the drawings.

[0033] Advantageously, the arm comprises two or more arm sections, wherein each two of the two or more arm sections are connected to each other by the damping material. In other words, in this embodiment, no more than two arm sections are connected by a single drop or bridge of damping material. However, of course, there can be more than one drop or more than one bridge of damping material spaced apart from each other, wherein each of them connects two arm sections. It should also be noted that two or more drops or two or more bridges of damping material can be connected to a single arm section, as long as they each lead to a different arm section.

[0034] In one embodiment, the at least two arm sections extend next to each other, forming a longitudinal gap between the at least two arm sections, in which the damping material is arranged. In other words, the arm comprises at least two relatively long arm sections which extend "in parallel", which here does not mean only straight arm sections, but in particular arm sections with a constant-width gap therebetween, independent of the particular course. These arm sections can move with respect to each other with a relatively high amplitude. The damping material helps to control this movement.

[0035] Beneficially, the ratio between the length of the gap and the width of the gap is > 20. Thus, the gap is relatively narrow, and the relative movement between the arm sections causes a comparably high shear stress within the damping material, and thus a comparably high damping.

[0036] In one embodiment, the at least two arm sections are arranged at a distance measured in the direction of the voice coil axis, which means that the width or height of the gap is measured in the direction of the voice coil axis. In other words, the arm sections of the arm extend above each other. The structure thus resulting can thus be regarded as a sandwich structure.

[0037] Advantageously, in the above embodiment, the distance between the at least two arm sections connected by the damping material is in the range of 5 pm < d < 100 pm. Experiments have shown that the damping is particularly effective in this thickness range.

[0038] In another embodiment, the at least two arm sections are arranged at a distance measured perpendicular to the voice coil axis, which means that the width of the gap is measured perpendicular to the voice coil axis. In other words, the arm sections of the arm extend side by side.

[0039] Advantageously, in the above embodiment, the distance between the at least two arm sections connected by the damping material is in the range of 20 μm ≤ d ≤ 100 μm. Experiments have shown that damping is particularly effective in this distance range.

[0040] Advantageously, the gap is produced by etching and / or by using a laser (eg by using a femtosecond laser). In this way, although the gap may be very narrow, it can still be produced with high precision.

[0041] Advantageously, the arm is L-shaped, U-shaped, S-shaped, arched, or meandering when viewed in a direction parallel to the voice coil axis. In this way, the arm can be made relatively flexible in a direction parallel to the voice coil axis (i.e., in the offset direction). As a result, the efficiency and acoustic power of the electrodynamic exciter are considerably higher. It should be noted at this point that a meander or arching shape is not necessarily "circular," but can also include, consist of, or approximate straight sections. Thus, straight sections can be connected by corners, or arcs can exist between straight sections.

[0042] Advantageously, the at least two arm sections are connected in the longitudinal direction of the respective arm, and

[0043] - bend alternately in different directions, or

[0044] Alternating straight and curved (wherein adjacent curved arm segments may be curved in different directions or have curvatures of different signs). Essentially, structures with alternating straight and curved arm segments are L-shaped and U-shaped, and structures that alternately curve in different directions are S-shaped or zigzag. Different directions in this context means curvatures of different signs. In principle, an arm can include both straight arm segments adjacent to curved arm segments and arm segments curved in a first direction adjacent to arm segments curved in a second direction.

[0045] In general, the proposed measures do not necessarily involve narrow gaps filled with damping material, but the damping material can also be present in the form of drops or bridges. This is particularly true if two arm sections are to be connected at a specific location.

[0046] Advantageously, in the above embodiment, the distance between at least two arm sections connected by the damping material, measured perpendicularly to the voice coil axis, is in the range 50 μm≤d≤400 μm. During experiments, damping proved to be particularly effective in this distance range.

[0047] In another advantageous embodiment, at least two arm sections can be made of different materials. In this way, the vibration behavior of the arm can be set within a wide range. For example, the first arm section can be made of a first metal (e.g., steel), while the second arm section can be made of a second metal (e.g., copper or aluminum).

[0048] In another embodiment, the arms are coated. This protects the metal of the arms from adverse environmental conditions, particularly oxidation. In particular, a different material than the damping material can be used for the coating. For example, a lacquer can be applied to the arms, particularly before they are connected via the damping material.

[0049] In another advantageous embodiment, the arm is coated with a damping material. Here, the damping material is applied to the arm, and then the damping material also connects the arm segments based on cohesive forces. Thus, connecting the arm segments and coating the arm segments can occur in the same process. However, it is also possible in principle to coat the arm with the damping material in a first step and connect the coated arm segments to the damping material in a second step. In this case, the coating on the arm segments can act as an adhesive.

[0050] In a particularly advantageous embodiment, at least one of the multiple arms is surrounded by or embedded in a damping material (when viewed parallel to the voice coil axis). The damping material thus forms a plate or membrane with an embedded metal arm. This arrangement is relatively easy to produce and provides considerable damping to the arm. To allow ventilation of the inner volume or space between the plate-like or membrane-like damping material and the plate-like structure or diaphragm, a duct can be provided to the inner volume or space. For example, the duct can be arranged in the magnetic circuit system, in the housing, or in the frame of the electrodynamic exciter. Recesses in the plate-like or membrane-like damping material can also allow ventilation. In this way, pressure compensation can be achieved between the inner volume or space and the space outside the electrodynamic exciter, which can improve the acoustic performance of the electrodynamic exciter. However, it is also possible to omit the duct or recess and render the inner volume or space airtight. In this way, dust and foreign particles can be kept away from the magnetic gap and away from the moving parts of the electrodynamic exciter. As a result, trouble-free operation of the electrodynamic exciter over a long period of time can be achieved.

[0051] Advantageously, in the above-described embodiment, the thickness of the damping material, measured in the direction of the voice coil axis, is in the range of 20 μm ≤ d ≤ 200 μm. During experiments, it was surprisingly found that a relatively thin damping layer with a thickness of only 20 μm ≤ d ≤ 200 μm contributed significantly to the damping of the arm, despite the metal used for the arm providing only low or almost no damping. This is particularly true if steel is used for the arm. Significant damping can even be achieved within the advantageous thickness range of 20 μm ≤ d ≤ 80 μm. While no significant improvement in damping is expected above 80 μm, thicker damping layers may provide improved longevity.

[0052] It is particularly advantageous if the coating consists of or contains a sprayed silicone resin. In other words, the coating is applied by spraying the silicone resin. In this case, an advantageous method for producing an intermediate product for an electrodynamic exciter is proposed, comprising the following steps:

[0053] providing at least one voice coil having an electrical conductor in the shape of a ring extending about a voice coil axis in a ring portion;

[0054] - providing a magnetic circuit system designed to generate a magnetic field transverse to the wire in the loop portion;

[0055] An arm assembly having a plurality of arms is manufactured, wherein

[0056] - The arm has a fatigue strength of at least 370N / mm 2 Or the ultimate tensile strength is at least 1100N / mm 2 of metal, and wherein,

[0057] - when viewed in a direction parallel to the voice coil axis, the arm is L-shaped, U-shaped, S-shaped, bow-shaped or meander-shaped;

[0058] - embedding the at least one of the plurality of arms in silicone, the silicone being sprayed onto the at least one of the plurality of arms and forming a damping material for the at least one of the plurality of arms, and

[0059] The at least one voice coil is coupled to the following components:

[0060] a) a magnetic circuit system, and allowing relative movement between the voice coil and the magnetic circuit system in an offset direction parallel to the voice coil axis, or

[0061] b) a movable part of a magnetic circuit system, and allowing relative movement of the voice coil and the movable part of the magnetic circuit system in an offset direction parallel to the voice coil axis.

[0062] Spray-on silicone is particularly suitable for high production speeds and, therefore, for the production of large quantities of electrodynamic actuators. For example, liquid silicone can be extruded from one or more nozzles for use in the manufacturing process of an embedded arm device. It should also be noted that the intermediate product comprises at least the aforementioned components, but may, as the case may be, include further components of the electrodynamic actuator, such as a frame or housing. It should also be noted that providing the voice coil and / or magnetic circuit system may include manufacturing the voice coil and / or magnetic circuit system. However, in this case, it is also possible to obtain ready-made components from a third party.

[0063] In another advantageous embodiment, the arms are coated with a coating (coated with a material different from the damping material) along with the damping material. For example, lacquer can be applied to the above device. Thus, the arms are first connected via the damping material, and then the resulting structure is coated with a second, different material.

[0064] Advantageously, at least two arm segments can have different stiffnesses. In other words, an asymmetry is introduced that helps adjust the vibration behavior over a wide range. For example, one arm segment can have a larger cross-section than the other arm segment. Alternatively or additionally, the first arm segment can be made of a first metal (e.g., steel), while the second arm segment is made of a second metal (e.g., copper or aluminum).

[0065] Advantageously, the average sound pressure level of the loudspeaker or electrodynamic transducer (or output device) measured at a normal distance of 10 cm from the sound emitting surface is at least 50 dB_SPL in the frequency range from 100 Hz to 15 kHz. AVG ” generally refers to the integral of the sound pressure level SPL in a specific frequency range divided by the frequency range. In the above context, it indicates in detail the ratio between the sound pressure level SPL integrated in the frequency range from f=100 Hz to f=15 kHz and the sound pressure level SPL integrated in the frequency range from f=100 Hz to f=15 kHz. In particular, the above average sound pressure level is measured at an electric power of 1 W, more particularly at a nominal impedance. The unit “dB_SPL” generally denotes the sound pressure level relative to the audibility threshold, which is 20 μPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] These and other aspects, features, details, utilities and advantages of the present invention will become more apparent from the following detailed description, the appended claims and the accompanying drawings, which illustrate features according to exemplary embodiments of the present invention, and in which:

[0067] Figure 1 An example of a loudspeaker with an electrodynamic exciter is shown in exploded view;

[0068] Figure 2 The cross-sectional view shows Figure 1speakers;

[0069] Figure 3 Shown Figure 1 An angular cross-sectional view of a loudspeaker viewed from below;

[0070] Figure 4 shows the voice coil assembly, arm assembly and frame separated from the rest of the loudspeaker as viewed from above in an angled view;

[0071] Figure 5 Angle view showing the Figure 4 device;

[0072] Figure 6 This is a bottom view of the speaker with the bottom plate removed;

[0073] Figure 7 shows a detailed angle view of the loudspeaker from below with the base plate removed and focusing on the first arm subassembly;

[0074] Figure 8 Shown is an oblique view of a device having a zigzag arm with two drops or bridges of damping material;

[0075] Figure 9 and Figure 8 Similar, but with drops or bridges in different locations;

[0076] Figure 10 Shown Figure 8 or Figure 9 How the device will move without the damping material;

[0077] Figure 11 is an oblique view of a device having arm sections extending side by side with damping material between the arm sections;

[0078] Figure 12 Shown Figure 11 How the device moves without damping material;

[0079] Figure 13 is an oblique view of a device having arm sections extending above and below each other with damping material therebetween;

[0080] Figure 14 Shown is a top view of an exemplary U-shaped arm;

[0081] Figure 15 Shown is a top view of an exemplary S-shaped arm;

[0082] Figure 16 Shown is a top view of an exemplary L-shaped arm;

[0083] Figure 17 shows a similar Figures 1 to 7 A top view of an arm assembly used in an electrodynamic exciter;

[0084] Figure 18 Shown is a variant with contact pads Figure 17 A top view of the arm device;

[0085] Figure 19 shows a top view of a single arm with a variation of the contact pad;

[0086] Figure 20 A top view of another arm showing a variation with contact pads;

[0087] Figures 21 to 29 Various embodiments of the spring are shown in top view;

[0088] Figure 30 shows an exemplary cross section through an arm wherein the arrangement formed by the arm and the damping material is coated with a separate coating material;

[0089] Figure 31 An exemplary cross section through an arm is shown wherein the damping material provides both damping and a coating;

[0090] Figure 32 shows a cross section through a first example of an electrodynamic transducer formed by an electrodynamic exciter connected to a plate; and

[0091] Figure 33 Shows something like Figure 32 An electric transducer in the invention but an electric transducer with a two-part magnetic circuit system.

[0092] Throughout the several views, the same reference numerals designate the same or equivalent parts. DETAILED DESCRIPTION

[0093] Various embodiments are described herein for various devices. Many specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments described in the specification and illustrated in the drawings. However, it will be understood by those skilled in the art that the embodiments may be practiced without such specific details. In other cases, well-known operations, components, and elements are not described in detail so as not to make the embodiments described in the specification unclear. It will be understood by those of ordinary skill in the art that the embodiments described and illustrated herein are non-limiting examples, and it will be understood that the specific structural and functional details disclosed herein may be representative and are not necessarily intended to limit the scope of the embodiments, which is limited only by the appended claims.

[0094] References throughout this specification to "various embodiments," "some embodiments," "one embodiment," or "an embodiment," etc., mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, appearances of the phrases "in various embodiments," "in some embodiments," "in one embodiment," or "in an embodiment," etc., throughout this specification are not necessarily all referring to the same embodiment. Furthermore, in one or more embodiments, particular features, structures, or characteristics may be combined in any suitable manner. Thus, particular features, structures, or characteristics illustrated or described in connection with one embodiment may be combined, in whole or in part, with features, structures, or characteristics of one or more other embodiments without limitation, as long as such combination is not illogical or non-functional.

[0095] It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise.

[0096] The terms "first," "second," and the like, if any, in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a particular order or chronological sequence. It is understood that the terms so used are interchangeable, where appropriate, so that the embodiments of the invention described herein can, for example, operate in a sequence different from that illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," "having," and any variations thereof are intended to cover non-exclusive inclusions, such that a process, method, article, or apparatus that includes a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0097] All directional references (e.g., "plus," "minus," "up," "down," "upward," "downward," "left," "right," "leftward," "rightward," "front," "back," "top," "bottom," "above," "below," "above," "below," "vertical," "horizontal," "clockwise," and "counterclockwise") are used for identification purposes only to aid the reader in understanding the present disclosure and are not intended to be limiting, particularly with respect to the position, orientation, or use of any aspect of the present disclosure. It is understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

[0098] As used herein, the phrases "configured to," "configured for," and similar phrases indicate that the subject apparatus, device, or system (e.g., through appropriate hardware, software, and / or components) is designed and / or constructed to achieve one or more specific intended purposes, rather than that the subject apparatus, device, or system is capable of performing only those intended purposes.

[0099] Joiner references (e.g., "attached," "coupled," "connected," etc.) are to be interpreted broadly and may include intermediate members between the connection of elements and relative movement between elements. Thus, joiner references do not necessarily infer that two elements are directly connected and in a fixed relationship to each other. It is intended that all matter contained in the above description or shown in the accompanying drawings be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims.

[0100] All numbers expressing measurement and the like used in the description and claims are to be understood in any case as being modified by the term “about” or “substantially”, which especially means a deviation of ±10% from the reference value.

[0101] By using Figures 1 to 3 An example of an electrodynamic exciter 1 a is disclosed. Figure 1 shows an exploded view of the electrodynamic exciter 1a, Figure 2 shows a cross-sectional view of the electrodynamic exciter 1a, and Figure 3 An angular cross-sectional view of the electrodynamic exciter 1 a as viewed from below is shown.

[0102] Typically, the electrodynamic exciter 1a is designed to be connected to the back side of the plate-like structure or diaphragm opposite to the sound emitting surface S of the plate-like structure or diaphragm. Figures 1 to 3 In the example shown, the electrodynamic exciter 1a is connected to the back of the diaphragm 2. The diaphragm 2 in this example comprises a flexible membrane portion 3 and a plate-shaped rigid membrane portion 4. However, the rigid membrane portion 4 is only optional and can be omitted. The electrodynamic exciter 1a forms a loudspeaker 5 together with the diaphragm 2. Therefore, in principle, Figure 1 shows an exploded view of the loudspeaker 5, Figure 2 shows a cross-sectional view of the loudspeaker 5, Figure 3 An angular cross-sectional view of the loudspeaker 5 as viewed from below is shown.

[0103] The electrodynamic exciter 1a includes an annular voice coil arrangement 6. In this example, the annular voice coil arrangement 6 includes a first voice coil 7a and a second voice coil 7b stacked one on top of the other and connected to each other by a glue layer. However, the electrodynamic exciter 1a may also include only one voice coil 7a. In any case, the voice coils 7a and 7b have an annular electrical conductor extending in the annular portion around the voice coil axis (or exciter axis) A. For example, the diameter of the metal core of the electrical conductor of the voice coils 7a and 7b may be ≤110 μm and / or the electrical conductor may further include an (electrically insulating) coating on the metal core.

[0104] The electrodynamic exciter 1a further comprises a magnetic circuit system 8, which in this example comprises a central magnet 9 and an outer magnet 10, as well as a central top plate 11 made of soft iron, an outer top plate 12 made of soft iron, and a bottom plate 13 made of soft iron. The central magnet 9 is mounted to the bottom plate 13 and the central top plate 11, and the outer magnet 10 is mounted to the bottom plate 13 and the outer top plate 12. The magnetic circuit system 8 is generally designed to generate a magnetic field B transverse to the longitudinal direction of the electrical conductor of the annular voice coil arrangement 6, which is wound around the voice coil axis (or exciter axis) A in the annular portion.

[0105] Furthermore, the electrodynamic exciter 1a comprises an arm assembly 14, which generally comprises a plurality of arms (or legs or levers) connecting the voice coil assembly 6 and the magnetic circuit system 8 and allowing relative movement between the voice coil assembly 6 and the magnetic circuit system 8 in an offset direction C parallel to the voice coil axis A. In this example, the arm assembly 14 comprises two arm subassemblies 15a, 15b, each of the arm subassemblies 15a, 15b having two arms (for more details, see Figure 6 and Figure 7 ).

[0106] Finally, the electrodynamic exciter 1 a comprises a frame 16 to which the diaphragm 2 (specifically, the flexible diaphragm portion 3 of the diaphragm 2 ), the outer magnet 10 , the outer top plate 12 and the bottom plate 13 are mounted. However, the frame 16 can be shaped differently than depicted and can hold different groups of components together. For example, it can be connected only to the outer magnet 10 or the outer top plate 12. It should also be noted that the arm arrangement 14 does not necessarily have to be directly connected to the voice coil arrangement 6 and the magnetic circuit system 8, but it can also be connected to them (indirectly), for example via the frame 16.

[0107] Figure 4 and Figure 5 The voice coil arrangement 6 , arm arrangement 14 and frame 16 are shown separated from the rest of the loudspeaker 5 . Figure 4 The device is shown in an angled view from above, and Figure 5 The device is shown from below in an angled view, wherein the device is turned around its horizontal axis.

[0108] also, Figure 6 a bottom view of the loudspeaker 5 is shown, in which the bottom plate 13 is removed, and Figure 7 a detailed angular view of the loudspeaker 5 is shown from below, in which the bottom plate 13 is removed and is focused on the first arm sub-arrangement 15a. In Figure 6 and Figure 7 the arms 17a..17d of the arm arrangement 14 are explicitly denoted by reference numerals.

[0109] Generally, the arms 17a..17d of the arm arrangement 14 are made of a metal having a fatigue strength of at least 370 N / mm 2 or an ultimate tensile strength of at least 1100 N / mm 2 and generally, each of the arms 17a..17d comprises at least two arm sections which are arranged movable to each other and which are connected to each other by a damping material having a tensile storage modulus of 0.1 Mpa - 6000 Mpa and a tensile loss factor of at least 0.1, each measured at room temperature of 20 °C.

[0110] In Figures 1 to 7 the damping material connecting the arm sections of the arms 17a..17d of the arm arrangement 14 is not explicitly shown, but this is now referred to in Figures 8 to 13 in more detail. Thus, Figures 8 to 13 the technical teaching of Figures 1 to 7 can be applied analogously to the arm arrangement 14 of

[0111] Figure 8 a perspective view of an arrangement having arms 17e is shown, which are very similar to the arms 17a..17d depicted in Figures 1 to 7 . Similar to the arms 17a..17d, the shape of the arms 17e is similar to a meander shape when viewed in a direction parallel to the voice coil axis A. As can be seen in Figure 8 , the arms 17e comprise connected arm sections s in the longitudinal direction of the arms 17e, which are alternately straight and curved and have different curvatures.

[0112] Furthermore, Figure 8 drops or bridges 18a, 18b of damping material are shown, each connecting two different arm sections s of the arms 17e which are arranged movable to each other (see also Figure 10 in this context). The distance b1 between the connected arm sections s measured in a direction perpendicular to the voice coil axis A is preferably in the range of 50 pm < d < 400 pm. In this way, the movement between the arm sections s can be substantially damped by the given material.

[0113] Figure 9Shows an oblique view of the device, which is similar to Figure 8 Instead, the drops or bridges 18a, 18b of damping material are arranged at different locations and connect different arm sections s of the arm 17e. However, with reference to Figure 8 The teachings disclosed above can be similarly applied to Figure 9 The device, in particular with regard to the teaching of the distance b2 between the connected arm segments s, can likewise preferably be in the range of 50 μm≦d≦400 μm.

[0114] Figure 10 shows how the arm sections s of the arm 17e can move relative to each other when the voice coil arrangement 6 is deflected. Figure 10 In the embodiment shown there are no drops or bridges 18a, 18b of damping material. However, in practice the drops or bridges 18a, 18b of damping material may be formed as shown. Figure 8 and Figure 9 The arm 17e is positioned as shown and damps the relative movement between the arm sections s of the arm 17e.

[0115] Figure 11 An alternative embodiment of an arm 17f is shown. The arm 17f has two arm sections s1 and s2 extending adjacent to each other, with a slit between the two arm sections s1 and s2 in the longitudinal extension of the arm 17f. Damping material 18c is arranged in this slit. Preferably, the distance b3 between the two arm sections s1 and s2 connected by the damping material 18c, measured perpendicularly to the voice coil axis A, is within the range of 20 μm ≤ d ≤ 100 μm. In this way, movement between the arm sections s1 and s2 can also be substantially damped by the given material.

[0116] Figure 12 shows how the arm sections s1, s2 of the arm 17f can move relative to each other when the voice coil arrangement 6 is deflected. Figure 12 The arm 17f is again shown without the damping material 18c, but it is easy to understand that the damping material 18c damps the relative movement between the arm sections s1, s2 of the arm 17f.

[0117] Figure 13A further alternative embodiment of an arm 17g is shown, which has two arm sections s1, s2 extending one above the other, with a slit between the two arm sections s1, s2 in the longitudinal extension of the arm 17g. A damping material 18d is arranged in the slit. Preferably, the distance b4 between the two arm sections s1, s2 connected by the damping material 18c, measured in the direction of the voice coil axis A, is in the range of 5 μm ≤ d ≤ 100 μm. In this way, the movement between the arm sections s1, s2 can also be substantially damped by the given material. Due to Figure 12 The structure of the device shown in Figure 12 The arrangement shown in can be considered and represented as a "sandwich".

[0118] exist Figures 8 to 13 In the embodiment of the present invention, each two arm segments s..s2 are connected to each other by means of a damping material 18a..18d. In this way, the damping effect can be set or selected in a differential manner. However, it is also possible that the damping material 18a..18d connects more than two arm segments s..s2 (in this context, see for example Figure 17 ).

[0119] exist Figures 11 to 13 In the example of , the ratio between the length of the gap and the width of the gap may be higher than 20, which means that the gap is relatively small. Therefore, the relative movement between the arm segments s1, s2 induces relatively high shear stresses in the damping material 18c, 18d and thus relatively high damping.

[0120] In one embodiment, at least two arm segments s, s2 can have different stiffnesses and / or be made of different materials. For example, one arm segment s1 can have a larger cross-section than the other arm segment s2. Alternatively or additionally, the first arm segment s1 can be made of a first metal (e.g., steel), while the second arm segment s2 can be made of a second metal (e.g., copper or aluminum). These measures can introduce an asymmetry that helps adjust the vibration behavior over a wide range.

[0121] Figures 14 to 16 A further alternative shape of the arms 17h..17j is now shown in a top view. In detail, Figure 14 A U-shaped arm 17h is shown, Figure 15 An S-shaped arm 17i is shown (having arm sections bent alternately in different directions), and Figure 16 An L-shaped arm 17j is shown. Figures 14 to 16 In FIG. 1 , the damping materials 18a..18d are not explicitly shown, but it can be easily understood that Figures 14 to 16 The arms 17h..17j may be damped by damping material 18a..18d, as in Figures 9 to 13 As outlined.

[0122] Reference Figure 15 It should also be noted that it can be difficult to clearly distinguish between an S-shape and a zigzag shape. However, in particular, when the angle of the bow reaches more than 180°, the S-shape may lead to a zigzag shape. Similar considerations can be made for bows, L-shapes, and U-shapes. In particular, a U-shape can be considered as a bow with an angle of approximately 180°, and in particular, an L-shape can be considered as a bow with an angle of approximately 90°.

[0123] Figures 17 to 19 A further example is shown, which is essentially based on Figures 1 to 7 The arms 17a..17d of the loudspeaker 5 disclosed in FIG.

[0124] Figure 17 Subassembly 15a of loudspeaker 5 is shown in a separate top view. The dashed lines indicate another embodiment of the proposed damping feature. In detail, arms 17a, 17b are surrounded by or embedded in a damping material 18e, which is particularly visible when viewed in a direction parallel to voice coil axis A (see dashed lines). Thus, damping material 18e forms a kind of plate or membrane. The thickness of damping material 18e, measured in the direction of voice coil axis A, is preferably in the range of 20 μm ≤ d ≤ 200 μm. In a more preferred embodiment, the thickness of damping material 18e is in the range of 20 μm ≤ d ≤ 80 μm. The relatively thin damping layer 18e substantially contributes to the damping of arms 17a, 17b, even though the metal used for arms 17a, 17b provides only low or almost no damping. This is particularly true if steel is used for arms 17a, 17b. Although no significant improvement in damping is expected above 80 μm, a thicker damping layer 18e may provide better lifetime.

[0125] If the entire arm device 14 is embedded in the damping material 18e, the plate-like or film-like damping material 18e and the diaphragm 2 (or the plate-like structure as the case may be, see herein) can be sealed airtight. Figure 32 and Figure 33 ). In this way, dust and foreign particles can be kept away from the magnetic gap and away from the moving parts of the electrodynamic exciter 1a. As a result, a long and trouble-free operation of the electrodynamic exciter 1a can be achieved.

[0126] Nevertheless, ventilation of the interior volume or space can also be permitted. To this end, ducts can be arranged in the magnetic circuit system 8, in the frame 16 (or, as the case may be, in the housing), and can lead to the interior volume or space. Recesses in the plate-like or film-like damping material 18e can also permit such ventilation. In this way, pressure compensation can be achieved between the interior volume or space and the space outside the electrodynamic exciter 1a, which can improve the acoustic performance of the electrodynamic exciter 1a.

[0127] Figure 18 An alternative example of subassembly 15a is shown. Generally, as previously described, arms 17a, 17b serve to mechanically connect voice coil assembly 6 and magnetic circuit system 8. Thus, the outer connecting section mechanically connects arms 17a, 17b to frame 16, and the inner connecting section mechanically connects arms 17a, 17b to voice coil assembly 6. Furthermore, arms 17a, 17b can also serve to electrically connect voice coil assembly 6. In this case, arms 17a, 17b have both mechanical and electrical functions. Optional inner contact pads 19 can be used to electrically connect voice coil assembly 6 to arm 17a, but inner connecting sections could also be used for this purpose. In this case, the inner connecting section serves both mechanical and electrical functions. The same is true for the outer connecting section, which can also serve both mechanical and electrical functions. Arm 17a may also include additional outer contact pads 20 (drawn in dashed lines).

[0128] exist Figure 17 and Figure 18 In the example shown, the inner contact pad 19 is arranged inside the inner bow. In this way, the area of ​​the inner contact pad 19 is relatively large, so that the voice coil assembly 6 can be reliably connected to the arm 17a (for example, by soldering, welding or gluing). However, only a small space is required for the connection of the magnetic circuit system 8 and the voice coil assembly 6. In other words, the inner contact pad 19 does not lead to an increase in the magnetic gap between the magnetic circuit system 8 and the voice coil assembly 6, so the efficiency and power of the loudspeaker 5 are relatively high. It should be noted that the same technical teachings with exactly the same advantages can be applied to the outer contact pad 20. Advantageously, it can be arranged inside the outer bow. Despite the advantages disclosed above, the inner contact pad 19' can also be arranged outside the inner bow 20 (drawn with a dotted line).

[0129] Figure 17 and Figure 18 It is also shown that the arms 17a, 17b are connected by an arm bridge 21, thereby forming a first arm sub-assembly 15a. The arm bridge 21 can have both mechanical and electrical functions as the case may be.

[0130] It should be noted in this regard that meanders are not necessarily "circular" but may also include Figure 17 and Figure 18In this example, the straight line segments are connected by circular segments, however, straight line segments can also be connected by corners. Circles can also be used instead of Figure 18 In other words, the term "zigzag" is to be interpreted broadly in this disclosure.

[0131] exist Figure 17 and Figure 18 In the example shown, the two arms 17a, 17b are connected by an arm bridge 21, but this is not a necessary condition. The voice coil device 6 can also be connected to the magnetic circuit system 8 via a plurality of separate arms 17a, 17b. An example of such a separate arm 17a is shown in FIG. Figure 19 Shown in.

[0132] exist Figures 17 to 19 In the example shown, the arms 17a, 17b have a meandering shape. This is not a necessary condition, and the arms 17a, 17b may also have different shapes. Figure 20 An example of an arm 17k is shown which has only one bow or is shaped like a bow when viewed in a direction parallel to the voice coil axis A. It should be noted at this point that the bow is not necessarily "circular" but may also include, for example, Figure 20 , consisting of, or approximating a straight line segment as in the case of FIG. In this example, the circular bow is adjacent to the straight line segment, but there is also a corner between the straight line segment and another segment. In other words, the term "bow" is to be interpreted broadly in this disclosure. It should be noted that the length or angle of the bow can also be smaller, so that when viewed in a direction parallel to the voice coil axis A, the arm 17 k can be more like an "L."

[0133] Already in the above Figures 17 to 19 The technical teaching disclosed in the context of Figure 20 , in particular with regard to the presence and arrangement of the contact pads 19, 19' and 20, with regard to the mechanical and / or electrical functions of the components of the arm 17b and with regard to the arm bridge 21. In particular, the contact pads 19, 19' and 20 can be arranged in the bow or in the corners of the L-shape.

[0134] Figures 21 to 29 Various further embodiments of arm arrangements 14b..14j with different types of arms 17l..17t are shown, which can be used in place of the arm arrangements 14a and arms 17a..17k of the embodiments disclosed above. Each of the arm arrangements 14b..14j comprises a central retaining portion 22 and one or more outer retaining portions 23. In detail, Figure 21 and Figure 22 Arm arrangements 14b, 14c are shown with exemplary alternative arcuate spiral arms 171, 17m. Figure 23 、 Figure 24 、 Figure 25 and Figure 26 Various arm arrangements 14d..14g are shown with arms 17n..17q which are shaped like a zigzag in top view. Figure 25 and Figure 26 An arm arrangement 14f, 14g is shown having arms 17p, 17q, which are embedded in damping material 18f, 18g. Figure 25 In the embodiment of , the outer retaining portion 23 can act as a natural boundary of the damping material 18f. Figure 26 In FIG. 1 , the dashed lines represent possible boundaries of the damping material 18g. It should be noted that although only the arm arrangements 14f, 14g are shown as having the damping material 18f, 18g, Figures 21 to 29 Other embodiments of the invention can also be provided with such damping material 18f, 18g. For embodiments with an outer retaining portion 23, it can again serve as a natural boundary for the damping material 18f.

[0135] also, Figure 27 、 Figure 28 and Figure 29 Various arm arrangements 14h..14j are shown with arms 17r..17t that change their winding direction. Thus, the arm arrangements 14h..14j can be considered to be made up of two nested spiral arrangements, each with an opposite winding direction. Thus, when the voice coil arrangement 6 is deflected, a rotation between the outer retaining portion 23 and the central retaining portion 22, and thus between the magnetic circuit system 8 and the voice coil arrangement 6, can be avoided or at least limited. Figures 21 to 25 and Figures 27 to 29 In the embodiment, there is an annular outer retaining portion 23 surrounding the arms 171..17p, 17r..17t, while in Figure 26 In the embodiment described above, a separate outer retaining portion 23 is used at the end of each arm 17q.

[0136] Advantageously, the arm arrangements 14a..14j and in particular the gaps between the arm segments s..s2 can be manufactured by etching and / or by using a laser (e.g. by using a femtosecond laser). In this way, the arm arrangements 14a..14j and the gaps can be manufactured with high precision, despite the potentially very fine structure.

[0137] Figure 30 Now it is shown that the arm (e.g. Figure 11 Here, the arrangement formed by the arm 17f and the damping material 18c is coated with a coating material 24, such as a polymer (e.g., thermoplastic, thermosetting plastic, elastomer, rubber). In this way, non-oxidation-resistant materials can be protected from oxidation.

[0138] Figure 31 Similar to Figure 30 However, instead of the separate coating material 24, a damping material 18c is used to provide both damping and coating. The joining of the arm segments s1, s2 and the coating thereof can be carried out in the same process. However, it is also possible in principle that, in a first step, the arm 17f is coated with the damping material 18c and, in a second step, the coated arm segments s1, s2 are joined with the damping material 18c. In particular, in this case, the coating on the arm segments s1, s2 can act as an adhesive.

[0139] It is also possible that the arm 17f is first coated with the coating material 24 and then the coated arm segments s1, s2 of the arm 17f are joined by the damping material 18c. In this case, the coating material 24 on the arm segments s1, s2 can also act as an adhesive.

[0140] It should be noted that further coatings can be applied to the structures shown in Figure 30 and Figure 31 In particular, the arm 17f or arm segments s1, s2 thereof can be coated with a metal.

[0141] In particular, the coating can consist of or comprise a sprayed-on silicone resin. More specifically, the silicone resin can act as a damping material. Thus, the silicone resin can act as the coating material 24 and / or the damping material 18c in Figure 31 and Figure 32

[0142] In an advantageous embodiment, a method of manufacturing an intermediate product for an electrically excited loudspeaker 1 a comprises the following steps:

[0143] providing at least one voice coil 7a, 7b having electric conductors in the shape of a ring extending around a voice coil axis A in a ring portion;

[0144] providing a magnetic circuit system 8 designed to generate a magnetic field B transverse to the conductors in the ring portion;

[0145] manufacturing an arm device 14a..14j having a plurality of arms 17a..17t. As previously described, the arms 17a..17t are made of a metal having a fatigue strength of at least 370 N / mm 2 or an ultimate tensile strength of at least 1100 N / mm 2 and the arms 17a..17t are L-shaped, U-shaped, S-shaped, arc-shaped or meander-shaped when viewed in a direction parallel to the voice coil axis A.

[0146] ​In a next step, at least one of the plurality of arms 17a..17t is embedded in silicone, which is sprayed onto the at least one of the plurality of arms 17a..17t and forms a damping material 18c for the at least one of the plurality of arms 17a..17t.

[0147] Finally, at least one voice coil 7a, 7b and magnetic circuit system 8 are coupled by using arm arrangements 14a..14j, thereby allowing relative movement between the voice coil 7a, 7b and said magnetic circuit system 8 in an offset direction C parallel to the voice coil axis A.

[0148] Alternatively, at least one voice coil 7a, 7b is coupled to a movable part 37 of the magnetic circuit system 8 by using arm means 14a..14j, thereby allowing relative movement between the voice coil 7a, 7b and said movable part 37 of the magnetic circuit system 8 in an offset direction C parallel to the voice coil axis A (see also in this context ). Figure 33 ).

[0149] Spray-on silicone is particularly well-suited for high production speeds and, therefore, for mass-producing the electrodynamic actuator 1a. For example, liquid silicone can be pressed through one or more nozzles for use in the manufacturing process of the embedded arm arrangements 14a, 14j. It should also be noted that the intermediate product includes at least the aforementioned components, but may include further components of the electrodynamic actuator 1a, such as the frame 16 or the housing, as appropriate.

[0150] Usually and applicable to Figures 1 to 31 In all examples, it is advantageous if the metal arms 17a..17t are made of or comprise steel, brass, bronze, molybdenum or tungsten. In this way, the metal arms 17a..17t are quite robust and can withstand the relatively high alternating mechanical loads caused by the deflections of the electrodynamic exciter 1a, i.e. by the relative movements between the voice coil arrangement 6 and the magnetic circuit system 8. This is particularly true if the metal arms 17a..17t are made of stainless steel, which makes the metal arms 17a..17t quite robust. In a very advantageous embodiment, the metal arms 17a..17t are made of a stainless steel having a strength of 370 N / mm 2 Up to 670N / mm 2 Fatigue strength within the range or 1100N / mm 2 Up to 2000N / mm 2The metal arms 17a..17t are made of cold-rolled stainless steel with an ultimate tensile strength in the range of 1.4404. Advantageously, austenitic stainless steel can be used for the metal arms 17a..17t, in particular stainless steel 1.4404. During the evaluation, this material proved to be particularly suitable for the requirements in the exciter design. Austenitic stainless steel has a high proportion of austenite and is therefore non-ferromagnetic or low-ferromagnetic. Therefore, when the metal arms 17a..17t move in the magnetic field in the magnetic gap of the magnetic circuit system 8, no or only very small (unwanted) forces are introduced into the metal arms 17a..17t. Such forces could change the (dynamic) idle position of the electrodynamic exciter 1a and degrade its characteristics. In addition, austenitic stainless steel does not or essentially does not magnetically bridge the magnetic gap of the magnetic circuit system 8. In other words, the metal arms 17a..17t do not form a magnetic short circuit in the magnetic circuit system 8. In addition, in addition to its previously presented properties, stainless steel also offers the advantage of its resistance to oxidation.

[0151] exist Figures 1 to 7 In the example shown, the electrodynamic exciter 1a is connected to the diaphragm 2, thereby forming the loudspeaker 5. However, this is not a necessary condition, but the electrodynamic exciters 1b, 1c may also be connected to the diaphragm 2. Figure 32 and Figure 33 The plate-like structure 25 shown in FIG. In this manner, electrodynamic transducers 26a and 26b are formed. Specifically, the plate-like structure 25 includes a sound-emitting surface S and a back surface opposite to the sound-emitting surface S. Electrodynamic exciters 1b and 1c are connected to the back surface thereof. To this end, the voice coil assembly 6 or the magnetic circuit system 8 may include a flat mounting surface intended to be connected to the back surface of the plate-like structure 25, wherein the back surface is oriented perpendicular to the voice coil axis A.

[0152] Figure 32 A first example of such an electrodynamic transducer 26a is shown. In practice, the electrodynamic exciter 1b looks very much like the electrodynamic exciter 1a for the loudspeaker 5. In contrast, the magnetic circuit system 8 is not connected to the plate-like structure 25 but is free to move relative to the voice coil arrangement 6. Figure 32 In the example shown in FIG, the frame 16 is omitted. However, the electric transducer 25a may include the frame 16 as appropriate.

[0153] Figure 33 An example of an electric transducer 26b is shown, which is similar to Figure 32The main difference is that the magnetic circuit system 8 includes a fixed part 27 and a movable part 28. In this example, the fixed part 27 is formed by an outer ring 29 made of soft iron, and the movable part 28 is formed by the central magnet 9, the central top plate 11, and the bottom plate 13. Another difference is that there is only one voice coil 7 instead of two. Finally, the arm subassemblies 15a, 15b are arranged on the inner side of the voice coil 7 and connect it to the movable part 28 of the magnetic circuit system 8. Therefore, the movable part 28 can move freely relative to the voice coil 7.

[0154] Typically, as described above, electrodynamic actuators 1b, 1c together with plate-like structure 25 form electrodynamic transducers 26a, 26b. For example, the plate-like structure can be a passive structure, such as part of a device housing, into which electrodynamic actuators 1b, 1c are built. However, the plate-like structure itself can also have specialized functions. For example, if plate-like structure 25 is embodied as a display, electrodynamic actuators 1b, 1c together with the display form an output device (for audio and video data).

[0155] In contrast to the diaphragm 2, the plate-like structure 25 has no dedicated flexible part in the sense of the present disclosure, as in the case of the diaphragm 2. Therefore, there is no extreme separation of deflection and piston movement, as is the case with the flexible diaphragm part 3 (deflection) and the rigid diaphragm part 4 (piston movement). Instead, the sound generation is accomplished via the deflection of the entire plate-like structure 25. Furthermore, when a plate-like structure 25 is used, the voice coil arrangement 6 or the magnetic circuit system 8 (or at least a part thereof) is connected to the plate-like structure 25 or is arranged fixedly relative to the plate-like structure 25. The force applied to the plate-like structure 25 can be determined by the electrodynamic exciter 1b, 1c relative to the plate-like structure 25 (which is located at the bottom of the plate-like structure 25). Figure 32 In the case of magnetic circuit system 8 and Figure 33 In this case, it is caused by the inertia of the moving part (in this case, it is the movable part 25 of the magnetic circuit system 8), or because the part of the electric exciter 1b, 1c that moves relative to the plate structure 25 is fixed to another part (for example, fixed to the housing of the device in which the electric exciter 1b, 1c is built).

[0156] It should also be noted that in the case where the electric exciters 1b, 1c are connected to the back of the plate-like structure 25, the arm arrangements 14a..14j can be regarded as spring arrangements, and in the case where the electric exciter 1a is connected to the back of the diaphragm 2, the arm arrangements 14a..14j can be regarded as suspension systems.

[0157] The proposed measures relate in particular to "small" loudspeakers 5. In the context of the present disclosure, a small loudspeaker is generally a loudspeaker 5 having a diaphragm 2 and / or a loudspeaker 5 having a back volume F which, when viewed in a direction parallel to the voice coil axis A, has a diameter of less than 600 mm. 2The area of the back cavity volume F is in the range from 200 mm 3 to 2 cm 3 The back cavity volume F is typically the volume "behind" the diaphragm 2 and can be a volume enclosed by a housing of the loudspeaker 5, by other parts of the loudspeaker 5 or by a housing of a device in which the loudspeaker 5 is built-in, e.g. a mobile phone.

[0158] Generally, the loudspeaker 5 or the electrodynamic transducer 26a, 26b (or output device) of the type disclosed above produces an average sound pressure level of at least 50 dB_SPL measured in a orthogonal distance of 10 cm from the sound emitting surface S1 in a frequency range from 100 Hz to 15 kHz. In particular, the above average sound pressure level is measured at 1 W electrical power, more particularly at nominal impedance.

[0159] It should be noted that the present application is not limited to the above described embodiments and exemplary working examples. Further developments, modifications and combinations are also within the scope of the patent claims and are mastered by the person skilled in the art from the above disclosure. Thus, the techniques and structures described and exemplified herein are to be understood as being illustrative and exemplary, and not to limit the scope of the present application. The scope of the present application is defined by the appended claims, including known equivalents and non-foreseeable equivalents at the time of filing the present application. Although many embodiments of the application have been described with a certain degree of particularity, the person skilled in the art can make numerous alterations to the disclosed embodiments without departing from the spirit or scope of the present disclosure.

[0160] It should also be noted that the drawings are not necessarily to scale and that the depicted parts can actually be larger or smaller.

[0161] List of reference signs

[0162] 1a, 1c electrodynamic exciter

[0163] 2 diaphragm

[0164] 3 flexible diaphragm portion

[0165] 4 rigid diaphragm portion

[0166] 5 loudspeaker

[0167] 6 voice coil arrangement

[0168] 7, 7a, 7b voice coil

[0169] 8 magnetic circuit system

[0170] 9 center magnet

[0171] 10..10d outer magnet

[0172] 11 center top plate

[0173] 12 outer top plate

[0174] 13 bottom plate

[0175] 14a..14j Arm assembly

[0176] 15a, 15b arm device

[0177] 16 Frame

[0178] 17a..17t Arm

[0179] 18a..18g Damping materials (e.g. bridges or drops)

[0180] 19, 19' inner contact pad

[0181] 20 external contact pads

[0182] 21 Arm Bridge

[0183] 22 Center holding part

[0184] 23 External retaining part

[0185] 24 Coating materials

[0186] 25 Plate-like structure (display)

[0187] 26a, 26b Electric transducer

[0188] 27 Fixed part of magnetic circuit system

[0189] 28 Movable parts of magnetic circuit system

[0190] 29 Outer Ring

[0191] A Voice coil axis

[0192] B Magnetic Field

[0193] C offset direction

[0194] F Back cavity volume

[0195] S sound emitting surface

[0196] b1..b4 distance between connected arm segments

[0197] s, s1, s2 arm segments.

Claims

1. An electrodynamic exciter (1a..1c) designed to be connected to the back side of a plate-like structure (25) or a diaphragm (2) opposite to the sound-emitting surface (S) of the plate-like structure (25) or the diaphragm (2), and comprising: - at least one voice coil (7, 7a, 7b) having an electrical conductor in the shape of a ring extending around the voice coil axis (A) in the ring portion; a magnetic circuit system (8) designed to generate a magnetic field (B) transverse to the wire in the annulus portion; and - an arm arrangement (14a..14j) having a plurality of arms (17a..17t), said arm arrangement (14a..14j) coupling said at least one voice coil (7, 7a, 7b) and a) the magnetic circuit system (8), and allowing relative movement between the voice coil (7, 7a, 7b) and the magnetic circuit system (8) in an offset direction (C) parallel to the voice coil axis (A), or b) a movable part (28) of the magnetic circuit system (8), and allowing relative movement between the voice coil (7, 7a, 7b) and the movable part (28) of the magnetic circuit system (8) in an offset direction (C) parallel to the voice coil axis (A), in, - the arms (17a..17t) are made of a material having a fatigue strength of at least 370 N / mm 2 Or the ultimate tensile strength is at least 1100N / mm 2 of metal, and wherein, - each of the arms (17a..17t) comprises at least two arm segments (s, s1, s2) arranged to be movable relative to one another and connected to one another by a damping material (18a..18g) having a tensile storage modulus of 0.1 MPa to 6000 MPa and a tensile loss factor of at least 0.1, both measured at room temperature of 20°C, The at least two arm sections (s, s1, s2) extend adjacent to each other, thereby forming a longitudinal gap between the at least two arm sections (s, s1, s2), wherein the damping material (18a..18g) is arranged in the longitudinal gap.

2. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that The arm (17a..17t) comprises two or more arm sections (s, s1, s2), wherein every two arm sections of the two or more arm sections (s, s1, s2) are connected to each other via the damping material (18a..18g).

3. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that The ratio between the length of the gap and the width of the gap is >20.

4. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that The at least two arm sections (s, s1 , s2) are arranged at a distance (b1 ..b4) measured in the direction of the voice coil axis (A).

5. The electrodynamic exciter (1a..1c) according to claim 4, characterized in that The distance (b1..b4) between the at least two arm sections (s, s1, s2) connected by the damping material (18a..18g) is in the range of 5 μm≤d≤100 μm.

6. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that The at least two arm sections (s, s1 , s2) are arranged at a distance (b1 ..b4) measured perpendicularly to the voice coil axis (A).

7. The electrodynamic exciter (1a..1c) according to claim 6, characterized in that The distance (b1..b4) between the at least two arm sections (s, s1, s2) connected by the damping material (18a..18g) is in the range of 20 μm≤d≤100 μm.

8. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that The gap is produced by etching and / or by using a laser.

9. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that When viewed in a direction parallel to the voice coil axis (A), the arms (17a..17t) are L-shaped, U-shaped, S-shaped, bow-shaped or meander-shaped.

10. Electrodynamic exciter (1a..1c) according to claim 9, characterized in that The at least two arm sections (s, s1, s2) are connected in the longitudinal direction of the respective arm (17a..17t), and - bend alternately in different directions, or -Alternately straight and curved.

11. The electrodynamic exciter (1a..1c) according to claim 10, characterized in that The distance (b1..b4) between the at least two arm sections (s, s1, s2) connected by the damping material (18a..18g) measured in a direction perpendicular to the voice coil axis (A) is in the range of 50 μm≤d≤400 μm.

12. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that The at least two arm sections (s, s1, s2) consist of different materials.

13. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that The arms (17a..17t.) are coated.

14. The electrodynamic exciter (1a..1c) according to claim 9, characterized in that The damping material (18a..18g) has a thickness measured in the direction of the voice coil axis (A) in the range of 20 μm≤d≤200 μm.

15. The electrodynamic exciter (1a..1c) according to any one of claims 1, 13 and 14, characterized in that The coating consists of or contains a sprayed silicone resin.

16. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that The arms (17a..17t) are coated together with the damping material (18a..18g).

17. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that The at least two arm sections (s, s1, s2) have different stiffnesses.

18. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that The arms (17a..17t) are made of or comprise steel, brass, bronze, molybdenum or tungsten.

19. Electrodynamic exciter (1a..1c) according to claim 18, characterized in that The arms (17a..17t) are made of stainless steel.

20. Electrodynamic exciter (1a..1c) according to claim 19, characterized in that The arms (17a..17t) have a fatigue strength of 370N / mm 2 Up to 670N / mm 2 The ultimate tensile strength is within the range of 1100N / mm 2 Up to 2000N / mm 2 Range of cold rolled stainless steel.

21. The electrodynamic exciter (1a..1c) according to claim 1, characterized in that At least some of the arms (17a..17t) are electrically connected to the at least one voice coil (7, 7a, 7b).

22. An electrodynamic exciter (1a..1c) according to claim 1, wherein The at least one voice coil (7, 7a, 7b) or the magnetic circuit system (8) comprises a flat mounting surface intended to be connected to the back side of the plate-like structure (25) opposite the sound emitting surface (S) of the plate-like structure (25), wherein the back side is oriented perpendicular to the voice coil axis (A).

23. A loudspeaker (5), characterized in that The loudspeaker (5) comprises an electrodynamic exciter (1a..1c) according to claim 1 and a diaphragm (2) fixed to the at least one voice coil (7, 7a, 7b) and the magnetic circuit system (8).

24. An electrodynamic transducer (26a, 26b) comprising a plate-like structure (25) having a sound-emitting surface (S) and a back surface opposite to the sound-emitting surface (S), and comprising an electrodynamic exciter (1a..1c) connected to the back surface, characterized in that The electrodynamic exciter (1a..1c) is designed according to claim 1.

25. The electrodynamic transducer (26a, 26b) according to claim 24, characterized in that The average sound pressure level of the electrodynamic transducer (26a, 26b) measured at a normal distance of 10 cm from the sound emitting surface (S) is at least 50 dB_SPL in a frequency range from 100 Hz to 15 kHz.

26. An output device, characterized in that The output device comprises an electrodynamic actuator (1a..1c) and a plate-like structure (25) according to claim 24, wherein the plate-like structure (25) is embodied as a display and the electrodynamic actuator (1a..1c) is connected to the back of the display.

27. A method of manufacturing an intermediate product for an electrodynamic exciter (1a..1c), said method comprising the steps of: providing at least one voice coil (7, 7a, 7b) having an annular electrical conductor extending in an annulus portion around a voice coil axis (A), - providing a magnetic circuit system (8) designed to generate a magnetic field (B) transverse to the wire in the loop portion, Producing an arm arrangement (14a..14j) having a plurality of arms (17a..17t), wherein - the arms (17a..17t) are made of a material having a fatigue strength of at least 370 N / mm 2 Or the ultimate tensile strength is at least 1100N / mm 2 and wherein each of the arms (17a..17t) comprises at least two arm segments (s, s1, s2), the at least two arm segments (s, s1, s2) being arranged to be movable relative to one another and connected to one another by a damping material (18a..18g) having a tensile storage modulus of 0.1 MPa-6000 MPa and a tensile loss factor of at least 0.1, the tensile storage modulus and the tensile loss factor both being measured at room temperature of 20°C, wherein the at least two arm segments (s, s1, s2) extend adjacent to one another, thereby forming a longitudinal gap between the at least two arm segments (s, s1, s2), - when viewed in a direction parallel to the voice coil axis (A), the arms (17a..17t) are L-shaped, U-shaped, S-shaped, bow-shaped or meander-shaped, - arranging said damping material (18a..18g) in said longitudinal gap, and The at least one voice coil (7, 7a, 7b) is coupled to the following components by using the arm arrangement (14a..14j): a) the magnetic circuit system (8), and allowing relative movement between the voice coil (7, 7a, 7b) and the magnetic circuit system (8) in an offset direction (C) parallel to the voice coil axis (A), or b) a movable part (28) of the magnetic circuit system (8), and allowing relative movement between the voice coil (7, 7a, 7b) and the movable part (28) of the magnetic circuit system (8) in an offset direction (C) parallel to the voice coil axis (A).

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