EA002480B1 - Acoustic device - Google Patents

Abstract

1. Acoustic device including a member extending transversely of its thickness and capable of sustaining bending waves causing consequential acoustic action by reason of areal distribution of resonant modes of natural bending wave vibration over its surface consonant with required achievable acoustic action of said member over a desired operative acoustic frequency range, wherein the member has a distribution of bending stiffness which varies over the area of the member for rendering said member favourable to said areal distribution of resonant modes for said acoustic action, said variation of bending stiffness including relatively higher and lower bending stiffness at different sides, respectively, of said location for bending wave transducer means and the centre of bending stiffness of the member is offset from the geometric centre of the member. 2. An acoustic device according to claim 1, wherein the centre of mass of the member is located at its geometric centre. 3. An acoustic device according to claim 2, wherein said variation of bending stiffness includes relatively higher and lower bending stiffness at different sides, respectively, of said location for bending wave transducer means. 4. An acoustic device according to any of claims 1 to 3, wherein said variation of bending stiffness includes relatively higher and lower bending stiffness at different sides, respectively, from said geometric centre of said element or said zone. 5. An acoustic device according to claim 3 or 4, wherein the centre of higher bending stiffness, where the initial stiffness moment is zero, is located from one side of the geometric centre of the member and the centre of lower bending stiffness, where the initial moment of reversed stiffness is zero, is located from the other side of the geometric centre of the member. 6. An acoustic device according to any preceding claim, wherein greater and lesser thicknesses of said member correspond to higher and lower stiffnesses, respectively of said distribution of bending stiffness. 7. An acoustic device according to any preceding claim, wherein said member has an additional mass or masses selectively provided having substantially no effect on desired acoustic action. 8. An acoustic device according to claim 7, wherein the or each additional mass is of sufficiently low mass that lower frequency acoustic action is substantially unaffected and has means of association with said member substantially effective to decouple the or each additional mass for higher frequency acoustic action. 9. An acoustic device according to claim 7 or claim 8, wherein the additional mass(es) are located such that the centre of mass of said member differs from the initial. 10. An acoustic device according to claim 9, wherein said desired position coincides with the geometric centre of said member. 11. An acoustic device according to claim 6, wherein said member is of sandwich structure having skins on a core having cell-defining walls extending through a varying thickness between said skins and defining cells of different cross-sectional size in order to provide the prescribed distribution of mass over said member. 12. An acoustic device according to claim 6, wherein said member is of sandwich structure having skins on a core having cell-defining walls extending through a varying thickness between said skins and in which the cell-defining walls are of different thicknesses in order to provide the prescribed distribution of mass over said member. 13. An acoustic device according to claim 11 or 12, wherein said prescribed distribution of mass is centred at the geometric centre of said member or said area. 14. An acoustic device according to claim 1, wherein said variation of bending stiffness includes at least one localised adaptation of the member being a relative weakening groove slot or cut into said member or any combination thereof. 15. An acoustic device according to any one of claims 1 to 5, wherein the member is of a structure having a skin and the bending stiffness variation is obtained by varying parameter(s) of the skin. 16. An acoustic device according to claim 15, wherein the thickness of the skin is a said skin parameter. 17. An acoustic device according to claim 15 or claim 16, wherein the Young's modulus of the skin is a said skin parameter. 18. An acoustic device according to any preceding claim, comprising acoustic transducer means having both bending wave and pistonic actions is located at a location which serves for bending wave transducer means to produce said acoustic action also serves for pistonic action acoustic transducer means. 19. An acoustic device according to claim 18, comprising acoustic transducer means producing bending waves and serving for pistonic action. 20. A loudspeaker drive unit as described according to any preceding claim, comprising: a chassis; a transducer supported on the chassis drivingly coupled to a panel diaphragm; a resilient edge suspension surrounding the diaphragm and mounting the diaphragm in the chassis, wherein the transducer is arranged to drive the diaphragm pistonically at relatively low audio frequencies to produce an audio output and to vibrate the diaphragm with bending waves at higher audio frequencies to cause the diaphragm to resonate to produce an audio output, the transducer being operatively coupled to the centre of mass and/or geometric centre of the diaphragm. 21. A loudspeaker drive unit according to claim 20, wherein the diaphragm is circular or elliptical in shape. 22. A loudspeaker drive unit according to claim 20 or claim 21, wherein the diaphragm comprises a lightweight cellular core sandwiched between opposed skins. 23. A loudspeaker drive unit according to claim 22 wherein one of the skins is extended beyond an edge of the diaphragm a marginal portion of the extended skin being attached to the resilient suspension. 24. A loudspeaker drive unit according to any one of claims 20 to 23, wherein the diaphragm is a distributed mode resonant panel. 25. A loudspeaker drive unit according to any one of claims 20 to 24, wherein the transducer is electromagnetic and comprises a moving coil mounted on a coil former the coil former being operatively coupled to the diaphragm. 26. A loudspeaker drive unit according to claim 25, comprising a second resilient suspension connected between the coil former and the chassis. 27. A loudspeaker drive unit according to claim 26, wherein one end of the coil former is connected to the diaphragm, the said second resilient suspension is disposed adjacent to the said one end of the coil former and a third resilient suspension is connected between the other end of the coil former and the chassis. 28. A loudspeaker drive unit according to any one of claims 25 to 27, wherein the end of the coil former adjacent to the panel diaphragm is coupled to drive the panel diaphragm substantially at one point. 29. A loudspeaker drive unit according to claim 28, comprising conical means connected between the coil former and the panel diaphragm. 30. A loudspeaker comprising an acoustic device as claimed in any one of claims 1 to 19 and a drive unit as claimed in any one of claims 20 to 29. 31. A stiff lightweight panel loudspeaker drive unit diaphragm adapted to be driven pistonically and to be vibrated to resonate with bending waves, the diaphragm having a centre of mass located at its geometric centre and a distribution of stiffness centred offset from its centre of mass. 32. An acoustic device according to any of claims 1 to 19, wherein said member has a bending wave transducer means to produce said acoustic action, at a location determined by said areal distribution of bending stiffness. 33. Loudspeaker drive unit actuator according to claim 30, comprising offset compliant and rigid drive coupling parts to drive a diaphragm pistonically centred on an axis and to provide offcentre resonant excitation to said diaphragm. 34. Loudspeaker drive unit actuator according to claim 33, comprising offset compliant and rigid drive coupling parts to drive a diaphragm pistonically centred on an axis including contribution by a least one said compliant part at lower frequencies and to provide offcentre resonant excitation to said diaphragm by at least one said rigid part at higher frequencies. 35. Loudspeaker acoustic drive unit actuator according to claim 33 or 34, comprising offset compliant and rigid drive coupling parts to drive a diaphragm pistonically at least at lower frequencies by way of at least one said compliant part and to excite vibration of said diaphragm by bending waves to cause distributed mode acoustic action at least at higher frequencies by way of at least one said rigid part. 36. Loudspeaker according to any of claims 33 to 35, wherein the rigid part(s) also contribute to the pistonic drive. 37. Loudspeaker according to any one of claims 33 to 36, wherein said parts are end-peripheral of a tubular member. 38. Loudspeaker according to claim 37, wherein the tubular member is secured to the diaphragm. 39. Method of making a panel member of or for an acoustic device according to any claims 1 to 19, the method including determining the nominal location of bending wave transducer means in the absence of bending stiffness variation and adjusting the areal distribution of bending stiffness variations to displace said nominal location for bending wave transducer means to a desired location by providing relatively higher and lower bending stiffness on opposite sides of said desired actual location and also on opposite sides of said nominal location. 40. Method according to claim 39, wherein said relatively higher and lower bending stiffness are along extensions of a notional straight line through said desired and nominal locations. 41. Method according to claim 39 or 40, the method including notionally superposing as a target geometry a desired or given configuration of the panel member and a subject geometry of a panel member

Description

FIELD OF THE INVENTION

The invention relates to acoustic devices capable of acoustic action by means of shear waves and typically (but not exclusively) intended for use in speakers or as such.

State of the art

At the same time, the PCT (international, according to the Patent Cooperation Treaty) under consideration, application number CB96 / 02145 mainly discloses the nature, structure and configuration of the elements of the acoustic panel, made with the ability to transfer and distribute the input vibrational energy through transverse waves in the acoustic working area (s) passing transverse to the thickness, usually (if not necessary) to the edges of the element (s). Particularly disclosed is an analysis of various specific configurations of panels with or without directed anisotropy transverse stiffness through / across said region (s), so as to have vibrational resonance components distributed over said region (s), preferably for acoustic coupling with ambient air; and so as to have a determined preferred location (s) within said region (s) for the acoustic transducer means, more particularly operatively active or moving parts thereof, effective with respect to acoustic vibration action in said region (s) and associated signals, usually electrical, corresponding to the acoustic content of such a vibrational action. This PCT application also provides for the use of such elements as “passive” acoustic devices or in such devices, i.e. without means of conversion, such as for reverb, or for acoustic filtration, or for the acoustic "sounding" of a space or room; and as “active” acoustic devices or in those with a transverse wave conversion means, including in a significantly wide range of speakers as sound sources fed by input signals that must be converted into the said sound, as well as microphones exposed to sound, which must be converted to other signals.

The concurrently pending UK patent application number (P.5840) relates to the use of mechanical impedance characteristics to achieve improvements in the geometry and / or location of the shear wave conversion means for panel elements such as or in acoustic devices. The contents of this UK patent application and the aforementioned PCT application are hereby incorporated by reference, which may be useful in explaining, understanding or defining the present invention.

This invention, in particular, is applicable in active acoustic devices in the form of loudspeakers using panel elements for use, as mentioned above (and what may be called here later acoustic radiators / resonant panels of distributed mode), but additionally achieves a satisfactory combination of piston action with action shear wave. However, there are more general or broader aspects of the invention, as is apparent from the following description.

SUMMARY OF THE INVENTION

From a first point of view, the invention relates to active acoustic devices based on the action of a shear wave in panel elements, providing a particularly effective placement for shear wave converting means, different from that disclosed in the aforementioned PCT application and in the application for a patent of Great Britain, i.e. in other locations compared to locations arising from analysis and preference in this PCT application, including even locations in the center (s) of mass and / or geometry, rather than offset from them.

From a second point of view, this invention relates to active acoustic devices based on the action of a transverse wave in the panel elements of the panel, especially providing an effective distribution of oscillations of the resonant mode, which may differ from that which follows from the description and preferences of the aforementioned PCT and Great Britain patent applications, even for the same configurations or geometry.

From a third point of view, this invention relates to active acoustic devices based on the action of a transverse wave in panel elements, especially providing an effective distribution of oscillations of the resonant mode in panel elements with configurations or geometry that differ from those considered as the most successful in the description and preferences of the above PCT and UK patent applications.

It should be noted that actual specific embodiments of this invention utilize panel elements substantially giving a surface distribution of vibrational components of a resonant mode for an acoustic effect generally comparable to or similar to that disclosed in the aforementioned PCT and UK applications, essentially based on the simple excitation of such an action by a substantially surface distributed acoustic shear wave for successful acoustic action; and not in some way just similar partial blanks for intentionally changing another acoustic action in panel elements for which such inherent action of a distributed resonant mode is not a design requirement, usually where other private additional structural means are performed to serve different frequency ranges and / or selectively suppress or specifically produce / impose vibrations in panel elements that are not inherently effective as in the above PCT and UK applications, as well as in this application, being typically unsuitable in terms of geometry and / or arrangement of the conversion means.

The method and devices of the invention include the spatial distribution of changes in stiffness, at least over a region (s) of such panel element (s) that are acoustically active with respect to the transverse wave action and the desired acoustic effect. It is obvious that such changes can be directly attributed to the displacement of the converter means from the locations that are specifically defined in the aforementioned PCT and UK applications, to the different locations of this invention and / or relative to similar patent applications, to the adaptation of disadvantageous configurations or geometry of panel elements more similar to advantageous configurations or geometry for acoustic action, including the spatial distribution of resonant modes of vibration arising from the action of a transverse wave, and / or are associated with the actual distribution of the resonant mode, which may differ in some way, at least due to the different spatial distribution of its bending stiffness, and to the resulting different arrangement for the converter means, or for both of these reasons.

In the aforementioned PCT application, panel element (s) are disclosed having different bending stiffness (stiffness) in different directions in the proposed acoustically active region (s), which may be the entire region of the panel element or an incomplete region, usually in directions relative to two coordinates or with expansion by two coordinates, and substantially constant along the coordinate. In contrast, the preferred panel element (s) of the embodiments of the present invention have changes in bending stiffness along a certain direction (s) in said region, which are indecomposable into constants in rectangular coordinates or in any direction (s).

A spatial change in bending stiffness is, of course, easily achieved by changing the thickness of the acoustic panel elements, but other possibilities arise, say, with respect to the thickness and / or density and / or tensile strength of the outer layers of the layered type and / or the reinforcement of monolithic structures, usually of composite type material (materials).

Since a practically accessible analysis cannot always allow such a study, which can accurately and fully identify and quantify changes in the actual spatial distribution of the acoustically effective vibration of the resonant mode for the panel element (s) of the present invention - even where they have a substantially similar geometry and / or average stiffnesses in respective directions, as with specific isotropic and anisotropic embodiments of the aforementioned PCT In the application, the practically resulting characteristic shows little if any significant reduction or degradation in the achieved successful acoustic characteristic, including the action of a shear wave, generally suggests a potential opportunity for its improvement. The beneficial effects (on the spatial distribution of the resonance mode oscillations) of a generally advantageous configuration / geometry in accordance with the aforementioned patent applications of the PCT and the United Kingdom can, however, be retained to a large extent, and can act in two groups or directions of aspects of the invention that implement one point of view .

One group / direction, as already mentioned, specifically providing a more convenient arrangement for the conversion means in acoustically active panel elements or their regions having configurations or geometry, known to be advantageous in isotropic or anisotropic versions in accordance with the aforementioned PCT and UK patent applications by shifting what is now called “natural” locations for the transducer means (in accordance with these patent applications) to other The provisions of this application, specifically relatively large bending stiffnesses to one side of such a natural arrangement, and comparatively smaller bending stiffnesses to its other side, or both. A portion (s) of greater bending stiffness are effective to offset such a natural arrangement from such a portion, usually from said one side to said other side and to a portion of less bending stiffness; wherein the portion (s) of lower bending stiffness serve to bias in the direction of its own portion (s). Another group / direction can be considered as including the ability to only partially determine the same, at least imaginary subgeometry of the geometry of the element of the common larger panel, which is not particularly advantageous for the good acoustic effect of the distributed mode, as in the aforementioned PCT and Great Britain patent applications; however, such subgeometry is not completely described and is not necessarily particularly advantageous in itself, but its partial definition has a significant improving effect on the acoustic effect of the distributed mode, for example, when striving for the type of configuration or geometry, known as including especially successful options, if at least not reaching such advantageous options; moreover, such an improving effect is especially effective, therefore, for the distribution of resonance modes at lower frequencies, but not necessarily (even preferably not) limits the action of the transverse wave of a higher frequency and the distribution of the resonance mode by such subgeometry, i.e. it allows such a distribution of vibration of the resonant regime of higher frequencies after determining the partial subgeometry and outside it.

With regard to easily achieving the desired or desired change in the spatial change in bending stiffness, the panel element (s) may have at least an inner layer (s), first configured as a substantially uniformly isotropic or anisotropic structure, say, as described in the above PCT applications and UK, including a multilayer structure (s) having outer layers on top of the inner layer (s). Then, a thickness change can be easily performed to achieve the desired spatial distribution of stiffness. For a deformable material, such as foam, such a change in thickness is achieved by selective compression or squeezing to obtain the desired contour, say, by controlled heating and applying pressure, usually to any desired profile, and this is achieved even after applying any outer layers (depending on the possibility of stretching such materials of the outer layer). Another possibility for the element is to have localized tightening or weakening, preferably a series of gradations thereof. For cellular or cellular materials, i.e., consisting of some suitable mesh sections of its cells extending from one outer layer to another common layered structure, or rigid form-retaining incompressible composites, a change in thickness is easily achieved by selective removal of the upper layer to the desired thickness of the contour / profile . None of these possibilities includes the necessary change in the geometric center, but the removal of the upper layer rather than compression inevitably leads to a change in the center of mass. The following discloses alternatives for the desired change in thickness / stiffness of the core thus made, including without changing the center of mass, which may be important for a transducer combining the piston action and the shear wave action, where the piston action is clearly best if centered with the center of mass coinciding and geometric center to avoid differential moments due to mass distribution relative to the location of the transducer and / or the effect of unbalanced pressure air.

The center of mass can be easily moved, usually to the geometric center, by selectively adding mass to the corresponding panel element, preferably without unacceptable effects on the desired spatial distribution of stiffness, i.e., the masses are also small enough not to unacceptably affect the action of the transverse wave of low frequency and effectively disconnect from the acoustic action of high frequency, say, low weight (s), suitably semi-compliantly installed in a hole in the panel, also small enough to unacceptably affect the acoustic effect.

An increase in stiffness in one direction from one side of the natural location for the location of the transducer means, or to one side of the aforementioned PCT and UK applications, or a decrease in stiffness in the completely opposite direction or to the other side will result in the transducer means of this invention being positioned in the general direction said one side, which may be preferable towards the geometric center. Such a relative increase / decrease in stiffness can be difficult for the resulting contour of the corresponding panel element, including narrowing the increased thickness / stiffness to the edge of the panel element and / or tilting the reduced thickness / stiffness, say, to obtain a substantially uniform thickness of the edge of the panel element.

Additionally or alternatively, the inventive concept with respect to at least one group / direction is visible in a panel element capable of acoustic transverse waves with the distribution of flexural stiffness over its acoustically active region, which is in no way centered until it coincides with the center the mass and / or geometric center of this panel element, although the location of the acoustic transducer means, both for the action of the transverse wave and for the piston action, or both The action can be substantially aligned such that it is often preferable.

It should be noted that there are two methods according to which the spatial distribution of stiffness over a panel element can be considered or treated as centered, one similar to how the center of mass is usually determined, i.e. first setting the stiffness moment to zero, thus in the sense of matching high stiffness (here the so-called "high center" of stiffness); the other way around is to set the reverse stiffness to zero first, thus in another sense corresponding to ductility or low stiffness (here the so-called “low center” of stiffness). In panel elements with isotropy or anisotropy, as specifically disclosed in the PCT application mentioned, these imaginary "high" and "low" centers of stiffness (as expressive in this context) actually coincide, and also normally coincide with the center of mass and the geometric center; but for a panel element with a stiffness distribution as in this application, these imaginary “high” and “low” stiffness centers are characteristically spaced and, moreover, usually separated from the center of mass and / or geometric center.

Returning to the actual or imaginary offset (by advantageous stiffness distributions in accordance with this invention) of the actual location for the shear wave transducer means (from the location (s) provided in accordance with the preferred options / analyzes of the above PCT and UK applications to a different location according to this application), such a displacement can be considered as directed towards the mentioned "low center" of rigidity, which it should thus be directed along the same direction as the desired imaginary displacement, and / or away from the aforementioned “high center” of stiffness, which may provide at least a structural design reference position to provide changes in the bending stiffness in the desired / required corresponding to its distribution. A change in the bending stiffness outside from such a “low center” to the edge of the panel element is usually associated with stiffness increasing to various values and with different speeds in many directions, at least in the direction of the “high center”.

Possible structures of the honeycomb central puff type may have the desired stiffness distribution due to the contribution of such a variant geometry of an individual element, and without a significant effect on the distribution and center of mass. Thus, the desired spatial distribution of stiffness can be achieved by changing the elements, as of any element, and the entire area of the section of the elements (if not also shape), the height of the element (indeed the core thickness) and the wall thickness of the element, including with this degree of change applied to increase / decrease as it may be desirable / necessary. A change in bending stiffness without distorting the mass distribution is achievable in this context, say, by changing the element wall thickness and element height for nominally the same element area, and / or by changing the element area and / or element height for the same element wall thickness, and stiffness can, of course, be increased or otherwise affected by a change in the outer layer, including a change in the number and / or nature of the folded layers.

Also, the present invention for panel elements is manifested in the presence of at least “low” centers of rigidity and practically the most effective location of the excitation device, which are identified and presented as typical opposite in terms of the spread of the minimum and maximum travel time to the edge of the panel for imaginary or real transverse waves, considered as coming from the "low center" of rigidity and from the location of the transducer, respectively.

Returning to the aforementioned second general view, panel elements with a stiffness distribution, as shown (which can probably be called “eccentric”), may be applicable to ensure that said panel is of a particular given or desired shape (t ie configuration or geometry) can exhibit a practically effective acoustic effect of a shear wave, which was not considered achievable until now for this particular form, at least not according to any of the preceding useful offers; moreover, not only for disadvantageous forms related to known beneficial forms, but also for forms not so related, but interpreted here as at least approaching what has so far been characterized as some particular beneficial form.

In general, this invention extends to the possibility of some physically feasible spatial distribution of the 9 flexible stiffness of irregularly shaped panel elements or for them, capable of the acoustic action of a transverse wave in order to accommodate such an action of a satisfactorily distributed characteristic of the resonant mode, and to provide a practically effective location (s) for shear wave conversion means (including finite element analysis), even non-reference whole or without reference to any provided or specified form, known as profitable. Such procedures can be carried out, at least to some extent practically, by trial and error regarding spatial stiffness distributions, but can be facilitated by analyzing this distribution using a method such as Finite Element Analysis, at least in terms of providing useful “Low” and “high” centers of rigidity, shown here as having a positive (approaching / attracting) and negative (receding / repelling) effect of location on the real the exact location for the means of transformation within the framework of such a spatial distribution of stiffness, whether it is accessible to analysis by itself or not.

In practice, beneficial effects are visible by looking for designs and / or transformations that can be used to deviate from what is known as an effective tool for specific geometric shapes and structures of panel elements to what can and will often be so, effective for another the panel geometry / structure, in particular, to show the structural characteristic of such another panel geometry with respect to the likely successful distribution of spatial stiffness and the location of the transducer pathogen ovatelya.

In one approach, considered here as part of the invention, attention is focused on the location of the transducer provided by imaginary overlaying as the standard geometry of the desired or given configuration of the panel element, and the object geometry of the panel element, which is known to be effective and for which it can be easily made or accessible analysis so that the desired standard transducer location matches the actual, preferably effective transducer location ator object geometry. Then, a bending stiffness distribution can be made so that for any or each of the selected structures with respect to the matching locations of the transducer of standard geometry and object geometry and for such geometries, the known / easily analyzed bending stiffness of the panel object structure can be transformed with respect to standard geometry to give substantially the same, or similar, or comparable gradation of stiffness distribution, as in object geometry, and acoustically successful shear wave action in standard geometry. In the future, such constructions include lines going from the matching locations of the transducer to the edges of standard geometry and object geometry or through them (say, as if at least representing the passage / intersection of a transverse wave). The provided related transformations depend on the relative lengths of the same construction lines in standard geometry and object geometry, and on the corresponding ratio, usually including the quotient of dividing the bending stiffness (B) by the mass per unit surface (μ), i.e. B / μ for proportionality transformations, including the third and / or fourth degree of the lengths of such lines to the edges of standard geometry and object geometry. Preferably, at least the standard geometry is smaller than the related object geometry, moreover, it is preferable that, when superimposed, a way is found to minimize the superiority of the latter over the former, including minimizing the conversion processing. Since in general in this way similar types of standard and object shapes or advantageous object geometry closest to disadvantageous standard geometry can be preferred, it is seen how possible for standard geometry to differ quite significantly from any recognizable type of known advantageous configuration / structure.

This is exactly the case when panels according to the aforementioned PCT application, which are isometric with respect to spatial bending stiffness and which are well studied / analyzed, are a good starting point for subjective geometries / structures. In general, another approach to the construction / transformation is seen, as potentially involving the search for correspondence in standard geometry / structure according to the method that the location of the transducer (now common) splits the flexural stiffnesses to each side in the object geometry / structure. Moreover, similar or related distribution schemes can be used not only between different types of geometry, but also if you want or need to give the standard geometry of one type of such distribution of flexural rigidity as similar or imitated to another type of geometry / configuration, as far as this type of geometry is practically / configurations (e.g., rectangular, elliptical) has a serious effect on the actual spatial distribution of the resonance mode oscillations, which Rudd can be significantly distorted.

For loudspeaker elements suitable for both a piston type and a shear wave type, the coincidence of the location of the shear wave conversion means with the center of mass and the geometric center is especially effective, as it allows one conversion device in one location to combine and perform both piston movement and shear wave excitation.

However, it is possible to use separate transducers, one for only piston action in the coincident center of mass / geometric center, and another for distance, conveniently located, as here, for the action of only the transverse wave, although then it may be necessary to balance the mass by adding masses (if this was not done together with the necessary distribution of bending stiffness).

A particularly interesting aspect of the invention pertaining to a single transducer that provides piston action as well as transverse shear wave action but in spaced apart positions can be used whether spacing is achieved by transverse wave transducer arrangement as here (say, to accommodate a convenient transducer configuration), or leaving behind how this is achieved without applying the above aspects of the invention.

In General, of course, the implementation of this invention may include mass distributions at a center of mass offset from the geometric center and / or any location of the transducer, or from any of them. In general, changes in bending stiffness and / or mass, at least in the acoustically acting region of the panel element, can be distributed in many prescribed ways and / or distributions, usually gradually in any particular direction to the desired ends, different from those given so far, and this will generally represent anisotropy that is asymmetric, at least with respect to the geometric center of mass; and the application is visible, as in the aforementioned PCT application.

Practical aspects of the invention include a loudspeaker drive unit comprising a chassis, a transducer supported on the chassis, a rigid lightweight panel diaphragm movably attached to the transducer, and an elastic edge suspension surrounding the diaphragm and mounting the diaphragm in the chassis in which the transducer is designed to drive the diaphragm in a piston manner at relatively low sound frequencies, in order to produce an audio output signal, and to generate diaphragm vibrations due to wave at higher sound frequencies to cause the diaphragm to resonate to produce an audio output signal, the device being such that the transducer is attached to the center of mass and / or the geometric center of the diaphragm, and the diaphragm has a distribution of bending stiffness, including a change such that leads to an acoustically effective resonant mode of operation of the diaphragm (at least centered with an offset from the center of mass).

The diaphragm can be round or elliptical in shape, and the transducer can be attached to the geometric center of the diaphragm. The diaphragm may comprise a lightweight honeycomb core inserted between opposing outer layers, and one of the outer layers may extend beyond the edge of the diaphragm, the extreme part of the protruding outer layer being attached to the elastic suspension.

The converter may be electromagnetic and may contain a movable coil mounted on the coil frame, and the coil frame is movably connected to the diaphragm. A second resilient suspension may be coupled between the coil frame and the chassis. One end of the coil frame may be attached to the diaphragm, and said second elastic suspension may be adjacent to said one end of the coil frame, and a third elastic suspension may be attached between the other end of the coil frame and chassis.

The end of the coil frame adjacent to the diaphragm panel can be attached to drive the diaphragm panel substantially at one point. For this purpose, conical means may be connected between the coil frame and the diaphragm panel.

The coil frame may comprise a malleable section radially offset from a rigid section so as to drive the diaphragm in a piston manner and to provide resonant diaphragm bias from the center.

In other aspects, this invention provides a loudspeaker comprising an excitation unit, as described above; and / or there is a rigid lightweight diaphragm panel of the loudspeaker excitation unit, adapted to be driven in a piston manner and to vibrate during resonance, the diaphragm having a center of mass located at its geometric center and a center of stiffness that is offset from its center of mass .

Brief Description of the Drawings

The following illustrates / describes a typical specific implementation with reference to the accompanying schematic drawings, in which FIG. 1Ά-Ό is a top view and three sectional views showing the desired location of the transverse wave transducer of the acoustic panel element, including the achievement by compressing the deformable core material or by profiling the core or composite material;

FIG. 2Ά, B, C are a top plan view and cross-sectional views of a core for an elliptical acoustic panel element of the present invention;

FIG. 3Ά, B, C are similar views of another elliptical panel element of the present invention;

FIG. 4Ά, B, C - acoustic panel element of unfavorable round shape, reduced to a more advantageous shape by partially creating an elliptical groove / groove, and a graph of the model distribution without such a groove / groove and with it;

FIG. 5Ά, B, C are diagrams useful in explaining possible distributions / structures / transformations to obtain a stiffness distribution for the desired or reference geometry for a rectangular panel element and secant / profile presentation of the results;

FIG. 6Ά, B, C are contour plots related to a useful methodology, including FIG. 5;

FIG. 7Ά, B are side and top sectional views of one embodiment of a loudspeaker drive unit of the present invention;

FIG. 8Ά, B are side views in section of another loudspeaker excitation unit and modifications;

FIG. 9Ά, B are side views in section of yet another loudspeaker excitation unit and modification;

FIG. 10Ά, B are perspective views of a connection or drive of a loudspeaker exciter for exploded application of a piston action and a shear wave action, and details of connection to a diaphragm / panel element; and FIG. 11Ά, B - relations for such actions and transition.

In FIG. 1Ά shows a substantially rectangular acoustic panel element 10Ά of a distributed mode, as if directly made in accordance with the aforementioned patent applications of the PCT and the United Kingdom, thus having its natural location 13 for a shear wave conversion means, offset from its geometric center 12 and from the actual diagonal, shown by a dashed line under the number 11. In the application of the present invention, however, the location 13 of the transducer must be in geometric skom center panel 12 10Ά element, i.e. in fact, be displaced along the solid line 15, which is achieved by the corresponding spatial distribution of the bending stiffness of the panel element. To this end, the bending stiffness is made relatively larger and smaller to one side (right in Fig. 1Ά) and to the opposite side (left in Fig. 1C) of the geometric center 12 and the “natural” location 13 of the transducer specifically in opposite directions along line 15 and its straightforward extensions 15C and 15b, respectively.

FIG. 1B is a section along line 15, including extensions 15C and 15b, and represents the same situation as FIG. 1Ά, i.e. The “natural” location of the converter 13B is likewise remote from the geometric center 1 2B of the distributed mode panel element 1 0B, see projection lines 1 2P, 1 3 P. FIG. 1B does not provide any details for the actual structure of the panel element 1 0B; but it shows alternative monolithic options, see solid lines on the outside 16X, Υ, or the layered type, see dashed inner lines 17X, Υ showing the outer layers attached to the inner core 18, usually (but not necessarily) a cellular foam type or cellular cellular type.

In FIG. 1C shows the use of a core 18C of a material that is deformable, specifically compressible, and capable of being crimped to a smaller thickness, which are many foam cellular materials suitable for distributed acoustic panels which are shown in FIG. 1C. Such compression is shown along the thickness of the core 18C, decreasing from right to left in FIG. 1C, and its elements go from rounded completely open (19X) to compressed (19Υ). Of course, it is not essential for these elements to have the same or similar size, or even arrangement, or to perform rounded completely open at maximum thickness (suitable foam materials are often of a compressed foam type). The core 18C is additionally shown with the outer outer layers 17Ά, B. It is possible, even normal, for the core material 18C to be deformed to the desired profile before the outer layers 17 присоедин, B are attached to it - but not significantly, since the panel element 10C is good for the acoustic effect of the distributed mode, if it is deformed by compression and the outer layers 17Ά, B are attached to it. The resulting large and smaller thickness of the core 18C and the panel element 10C will correspond to more and less bending stiffness; and the shown profile of the gradual change in thickness, and thus rigidity, so as to cause the location of the transducer 13C to coincide with the geometric center 12C, see arrow 138 and rounded merged links 12C, 13C. The compression deformation will normally be performed by heat treatment and using a suitably shaped compression plate. Here, the center of mass of the panel element 10C will not change, i.e. the center of mass will remain coincident with the geometric center 12C, now also coinciding with the location 13C of the transducer.

When the contribution of core density is small, i.e. bending stiffness is predominant, the linear contribution of the mass of the core can be neglected, and the desired spatial distribution of the thickness can be achieved by shaping the thickness of the isotropic core of polymer foam or assembled cellular laminate, or monolithic without an outer layer and core; and any such structure can be assembled, machined or cast as desired here.

In FIG. 1Ό shows an acoustic panel element 10Ό of a distributed mode with a gradually changing relief of its lower surface, so that its thickness decreases, having a profile similar to that of FIG. 1C. Such a profile may be somewhat different in order to obtain the same expected effect, i.e., to achieve the coincidence of the location 13Ό of the transducer with the geometric center 12Ό, for example, depending on the material used for the panel element 10Ό. Such materials may be monolithic reinforced composites or some kind of honeycomb, usually in this case as a core with outer layers, including a honeycomb type with cells passing through, extending from one outer layer to another. Foam cellular material at 19 ° in FIG. 1Ό may correspond to the use of foamy material, which optionally either does not compress or is not suitable for compression; but it is intended to show that there are no significant changes in density. There should be a change in the distribution of mass, and the center of mass of the panel element 10Ό will thus be offset from the geometric center, mainly in the direction of the arrow SM. In order to achieve a coincidence of the common center of mass with the geometric center 12Ό, the panel element 10Ό is shown with at least one additional balancing mass 22, shown mounted in a preferably blind receiving hole 23, further preferably using semi-flexible means 24, for example, in mechanically or mechanically suitable with glue attached to the sleeve or sleeve, so that its inertial effect gradually disconnects from the panel element 10Ό at higher frequencies of the desired distribution natural oscillations. There may be more than one balancing mass (22), say, offset less than 180 ° along an imaginary continuation line 15b, or some other arrangement, and they need not have the same mass, but may have a gradually decreasing mass along away from line 15b.

Most simply, the thickness can simply be narrowed towards the end along the section of FIG. 1B, although normal is a more complex contraction, including a common equal thickness of the edge and / or its gradual decrease from the line 15156, b. The geometric ratios of the bending frequency to size must be taken into account. For any given shape, increasing its size reduces the fundamental vibration frequencies and vice versa. The actual offset of the preferred location of the transducer can be considered the equivalent of reducing the actual size of the panel relative to the bend along the direction of such a shift.

Turning now to FIG. 2A-C and 3A-C, on them all panel elements are shown as having an elliptical shape, the ones indicated by 20A, 30A being isotropic, thus showing at 25, 35 the coincidence of the geometric center and the center of mass. From the point of view of meaning for the geometry and structures of the isometric panel, the stiffness distribution will, of course, also be centered at 25, 35 - either in the “high center” (stiffness as such) or in the “low center” (softness or suppleness). In addition, FIG. 2A, 3A show in 26, 36 one preferably good or better location (as in the aforementioned PCT application) for the transverse wave action transducer and acting for the desired acoustic characteristic of the resonant mode of the panel element 20 A, 3OA, for example a loudspeaker or part of a loudspeaker.

Turning now to FIG. 2B, C and 3B, C, in which the positions of the centers of the panels 10B, 20B, 30B are now indicated 25, 26 and 35, 36, and still correspond to both the geometric center and the center of mass, but here also additionally correspond to the acoustically effective location of the transverse transducer waves (26, 36). Compared to FIG. 2A, 3A, the locations of the transducer 26, 36 were effectively offset by the distribution of their bending stiffness, and the corresponding displacements of the “high” and “low” centers of rigidity are shown 27, 28 and 37, 38 as being generally opposite relative to the geometric centers 25, 35. This different asymmetric stiffness distribution is shown as achieved by gradual changes in the cells 29, 39, in particular in their height, thus changing the thickness of the panel elements 20 A, 30 A; and also possibly changes in their region and filling density (see Fig. 2B, C), or their region and wall thickness, but not their filling density (see Fig. 3B, C), thus achieving the desired stiffness distribution without, at least , a significant distortion of the mass distribution, and thus, the center of mass now coincides with both the geometric center and the location of the transducer (25, 26; 35, 36).

Additional approaches to changing stiffness, and thus spatial distribution, are possible; say, by introducing formations emerging from the plane, such as bends, roundings, etc., affecting stiffness by generally understandable methods; or such as grooves, grooves or grooves in surfaces to reduce stiffness, or rib formations to increase stiffness, including gradually using an spaced series of such formations, say, along extension lines 15C. B in FIG. 1A (not shown, but can be calculated using a method such as Extreme Element Analysis).

In FIG. 4A shows another application of intra-surface grooves, grooves, or grooves, especially to improve the effect of a shear wave of a distributed mode for an acoustic panel element 40, which actually has a configuration or geometry called round, which is known to be disadvantageous for an acoustic panel element of a distributed mode, especially with a central the location of the exciting means of the Converter. This well-known unsatisfactory feature is shown by the mode frequency distribution shown in FIG. 4B, as specialists who specifically correspond to the concentric oscillation format can easily recognize and understand. A major improvement in what is shown in FIG. 4C was achieved by forming grooves, grooves or grooves, as shown in 45 in the form of an ellipse part, i.e., in a certain class of configurations / geometry, known as including the most advantageous as an acoustic panel element of a distributed mode (as in the aforementioned FIG. 2, 3), although in reality it is not in accordance with such a well-known as a profitable concrete ellipse. However, the effect on the action of the lower frequency mode is much better distributed than the symmetry of simple centrally excited circular shapes, and the action of the higher frequency mode can spread beyond and outside the open ends of the groove 45. The shape of the groove 45 was developed using the Finite Element Analysis, see The shown figure is a complex element, moreover, this technology has the main purpose, in the detailed implementation of this invention. Less curved formations asymmetrically located relative to the center of the circular panel element are also promising, and can be easily improved with the help of an additional analysis of the extreme element.

In FIG. 5A, B show the construction and transformations, much the same as those described above, specifically shown for rectangular configurations / geometry of the control (51A, B) and object (52A, B). Structural lines 53A, B, machined according to different lengths and desired / required bending stiffnesses, show promising effectiveness of the approach, at least as applied to molds of the same rectangular type. The methodology of FIG. 5B is particularly attractive in that the subjective configuration / geometry 52B is rationally constructed from a control configuration / geometry 51B placed in one corner by extensions from that angle, so that the preferred arrangement of transducer 54B of a well-understood and analyzed isometric shape 52B simply coincides with the geometric center of the control form 51B. In FIG. 5C shows a typical section through the control element 50 of the control form 51A, obtained from the methodology of FIG. 5B.

The study of the partial B / μ or the values of the parameters B and μ, specifically separate from the other constant taken, in different radial directions 53B, and the mathematical distribution from the panel of the form 52B to the panel of the form 51B, allows us to calculate the distribution of stiffness in these directions (53B), additionally using a ratio of degrees, including a fourth degree of length and a second or third degree of thickness, depending on whether the required bending stiffness is the rigidity of a panel of a layered structure with a core and outer layers, or monol a solid solid structure of composite without external layers.

In FIG. 6A shows the results of the length distribution for the methodology of FIG. 5B, and in FIG. 6B shows how the desired (control) curvature mode relates to the results of FIG. 6A and with respect to material properties, specifically of one stiffness, including a fourth degree of length (solid line), thickness of a layered structure, including a square degree (dotted line), and thickness of a monolithic structure, including degree 4/3 (dashed line). For a layered structure, the rigidity of the outer layer (tensile strength) should also include a fourth degree of length; and a degree of 4/3 of the thickness of the outer layer. In FIG. 6C shows a modal density distribution with 3% damping for a control square panel element, without flexural stiffness distribution with a ratio of 1.134: 1 aspect of the isometric panel element according to the aforementioned PCT application, i.e. including adjustment regarding the difference on one side only; and a square panel enhanced by distributing bending stiffness according to the parameters of the outer layers, in particular thickness (11) and Young's modulus (E).

Referring to FIG. 7A and 7B, the loudspeaker drive unit comprises an open frame shaped chassis 71 made in the form of a shallow round basket or plate having a peripheral flange 71E protruding outwardly with drilled holes through which the drive unit can be mounted on a partition (not shown), for example , in a speaker housing (not shown), in a generally conventional manner. The chassis 71 supports the converter 72 in the form of an electrodynamic drive motor comprising a magnet 73 inserted between the pole pieces 74A, B and having an annular gap in which a tubular frame 75 of the coil is mounted, supporting the coil 75 C, which forms a driving connection or driving motor element .

The coil frame is mounted on elastic suspensions 76A, B at its opposite ends to guide the coil frame for axial movement in the gap of the magnetic assembly. One end of the frame of the coil 75 is attached, for example, via a connection 77, to the rear surface of the lightweight rigid panel 70, which forms the acoustic emitting diaphragm of the loudspeaker drive unit, and which contains a lightweight honeycomb core 70C, for example, of a honeycomb material inserted between the opposite front and the rear outer layers 70E, B. The panel 70 generally, as indicated, has a specific distribution of bending stiffness, providing a match between the center of mass and the preferred location of the pathogen across ary wave at its geometric center. In the example shown, the front outer layer preferably has a conventional circular shape combining with the contour and, in some cases, combining in effective action with the surroundings / suspension. The back outer layer is selected rectangular to form a composite panel consistent with the concept of a distributed mode (it can be excited directly using the differential connection device of Figures 10A and 10B).

For a simple central or central equivalent drive, the distributed mode panel section will be designed with a preferred modal distribution, such as is typically generated in this invention, for example, by controlling spatial stiffness, so that it is useful to place the modal point or excitation portion in the geometric center and center of mass or adjacent to it. Thus, a good modal excitation at higher frequencies and a piston action at lower frequencies are obtained for the usual type of structure and pathogen geometry.

The front outer layer 70E of the panel 70 protrudes beyond the edge of the panel, and its peripheral edge is attached to the surroundings or suspension of the coil 77 supported by the chassis 71, as a result of which the panel can move freely in a piston manner. The Converter 72 is designed to move the panel 70 in a piston manner at low frequencies and message the panel 70 oscillations at high frequencies, to transmit the panel transverse waves, as a result of which it enters the resonance, as described in detail above.

The devices shown in FIG. 8A and 8B are generally similar to the devices described above, except that in these cases the chassis 81 is even smaller, the engine 82 protrudes more outward of the chassis 81, and the frame of the coil 85 of the attachment / actuating device enters the chassis with a corresponding change in its suspension 86. The modification of FIG. 8B includes the use of a smaller neodymium motor 82Ν and a reduction in the cross section of the end 85 A of the frame of the coil 85.

The devices shown in FIG. 9A and 9B are very similar to the devices shown in FIG. 8A and 8B, except that the protruding end 95A. In the frame of the coil 95 is formed [of one] of a double conical section, the sharp end of which 95P approaches the rear surface of the light rigid panel diaphragm 90 in its geometric center.

In FIG. 10A, B shows the attachment / actuation device of the diaphragm 100, typically a drive motor coil frame (not shown) having a main rounded peripheral portion 108 of its driving end, which is adapted to attach (107) to a rigid light panel 100 made of semi-flexible material; and with a rounded peripheral portion 109 of the same rigid end. The driving action applied to the panel 100 will be reciprocating at low frequencies in both rounded peripheral end portions 108, 109. At high frequencies, the attachment / actuation device will excite the shear wave with the smaller portion 109, thus the vibration energy in the panel 100 in position it is offset from the axis of the attachment / actuation device 105. Due to its semi-compliant nature, the main rounded peripheral end portion 108 will be substantially stationary at high frequencies. Thus, the true operating position of the drive is frequency dependent, even though it is applied in the same manner and by the same means 105.

The simple case of one directly connecting section and one semi-flexible section can be extended to many stable contact points and more complex semi-flexible devices, for example, two or more preferred transmitter locations of a distributed mode panel element can be included. The semi-malleable section can be tapering, or gradually vary, or have many steps in thickness or volume to provide gradation of the attached stiffness interactively calculated with the acoustic characteristics of the panel to improve the overall performance, or with a distributed acoustic panel with the location of the transverse wave transducer, remote from the geometric center / center of mass in order to select a convenient structure for the device 105 of the connection / actuation or the last one, chosen for such a transducer location as in the aforementioned patent applications PCT and UK.

Such a differential frequency coupling device (105) can be used with a conventional motor coil used in electrodynamic exciters. Since such a device 105 can be a separate component of a predetermined size or diameter, it is convenient to consider its use as part of the level of attachment of a motor coil of a similar diameter, which, as shown above, can be selected so as to comprise one or more of the preferred converter locations drive the acoustic panel element of the distributed mode, especially on the rigid end portion 108 and excited by it, as the intended response signal is higher low frequencies is obtained by vibrations of the bending mode in the diaphragm of the acoustic panel element of the distributed mode 100. At lower frequencies, the contribution of the semi-flexible parts / inserts 108 becomes larger, and the entire periphery of the attachment / actuation device 105 is gradually activated for the balanced action of the center of mass, and, thus Satisfactory piston performance at low frequencies. The main bending frequency of the panel element 100 and the elasticity of the attachment / actuation portion 108 are selected so as to provide a satisfactorily smooth transition in acoustic power from the piston portion of the frequency range to the distortion vibration portions. Such a transition can be further facilitated by creating a multi-stage part 108 or narrowing, as shown by 108A.

Understanding the operation of this attachment device 108 is facilitated by FIG. 11a, representing the estimated change in speed applied to the acoustic panel, including in the transition area (crossover). At low frequencies, the semi-flexible part (s) 108 communicates the effective power to the panel element 100 in a balanced piston manner. This piston-like action decays with increasing frequency since the mechanical resistance of the vibrating panel element 100 becomes dominant and is excited at a preferably eccentric location (s). Thus, the contribution of active speed at higher frequencies arises from the hard, biased sector of the attachment device.

In FIG. 11B further shows the offset of the actual change in the points of the piston drive and the excitation of the distributed mode with frequency. At low frequencies, the piston drive point is dominant in the center and center of mass. With increasing frequency, there is a transition to a transverse wave excitation point offset from the center, aligned by a suitable choice of panel design, as well as the diameter of the complex attachment / actuation device and the geometry of the parts, to trigger at or near the preferred point of the distributed mode for satisfactorily beneficial distribution of vibration modes.

In the above FIG. 7 A, B, a transverse-wave transducer of this type with a full diameter in the range of 150 to 200 mm will affect the “natural” location of the transducer of the distributed mode panel element of a satisfactory transverse-mode characteristic starting in the range of 150 to 500 Hz. The piston action will be effective at low frequencies, for example, from 30 Hz for a suitable acoustic installation, and will decrease in its upper range, as the panel element falls into the range of the bending mode.

The ability to separate frequencies and interconnect devices according to this invention allows a subtle improvement to be made to use distributed mode acoustic panel elements. For example, in this panel, a change in the point of the drive with the frequency can be found desirable for frequency control purposes that are visible in individual applications, such as when fastening walls in small enclosures and connected media that change the output signal. More than one gradation or size / area of semi-flexible parts or inserts can be effectively used on the appropriate geometry of the attachment device to gradually or step by step move between the more or more effective starting point of the modal template with frequency and it is advantageous to change the emitted sound.

Claims (43)

CLAIM 1. An acoustic device comprising a panel-like element whose thickness is substantially less than its width and which is adapted to withstand flexural vibrations, resulting in an acoustic effect through the zonal distribution of resonant modes of natural flexural vibrations along its surface compatible with the desired achievable acoustic action of the said element in desired operating frequency range of the sound frequency, the element having a flexural rigidity distribution that varies along ONET this element for said member more favorable said zonal distribution of resonant modes for said acoustic action, and the center of bending stiffness of the element is offset from the geometric center of the element. 2. Acoustic device according to claim 1, in which the center of mass of the element is located in its geometric center. 3. An acoustic device according to claim 2, wherein said change in flexural rigidity distribution is achieved by providing relatively greater and smaller flexural rigidity from different sides of said location for a flexural vibration transducer. 4. An acoustic device according to any one of claims 1 to 3, in which said change in the distribution of flexural rigidity is achieved by providing relatively greater and smaller flexural rigidity from different sides of said geometric center of said element or of said zone. 5. Acoustic device according to claim 3 or 4, in which the center of greater bending stiffness, where the initial moment of stiffness is zero, is located on one side of the geometric center of the element, and the center of the lesser bending stiffness, where the initial moment of inverse stiffness is zero, is located with the other side of the geometric center of the element. 6. Acoustic device according to any one of claims 1 to 5, in which the greater and lesser bending stiffnesses are provided respectively by means of a greater and lesser thickness of said element. 7. Acoustic device according to any one of paragraphs. 1-6, in which additional mass or additional masses are selectively located on said element that do not have a significant effect on the desired acoustic effect. 8. The acoustic device according to claim 7, in which this additional mass or each of the additional masses is sufficiently small, so that the acoustic effect of a lower frequency does not have a significant effect on the resulting acoustic effect, and additionally provided a means of connecting the mass with the said element, providing separation of the additional mass or each of the additional masses for the acoustic effect of a higher frequency. 9. Acoustic device according to claim 7 or 8, in which the additional mass or additional masses are arranged in such a way that the location of the center of mass of the said element differs from the original. 10. Acoustic device according to claim 9, in which the location of the center of mass of the element coincides with its geometric center. 11. Acoustic device according to claim 6, in which said element has a layered structure containing outer layers on a core having a cellular structure formed by walls, the walls passing through a variable thickness of the element between the outer layers and forming cells of different sizes in cross section to to ensure the specified mass distribution on the mentioned element. 12. Acoustic device according to claim 6, in which the said element has a layered structure containing outer layers on the core having a cellular structure formed by the walls, the walls passing through a variable thickness of the element between the outer layers and have a different thickness to provide the specified mass distribution on the mentioned element. 13. Acoustic device according to claim 11 or 12, in which said predetermined distribution has a center of mass in the geometric center of said element or said zone. 14. The acoustic device according to claim 1, wherein said change in the distribution of flexural rigidity is achieved by performing a weakening groove, or groove, or notch, or any combination of said groove, groove, or notch in said element. 15. Acoustic device according to any one of claims 1 to 5, in which the element has a structure comprising an outer layer, wherein a change in bending stiffness is provided by changing the parameter (s) of this outer layer. 16. Acoustic device according to claim 15, in which the aforementioned parameter of the outer layer is its thickness. 17. The acoustic device according to claim 15 or 16, in which the said parameter of the outer layer is its Young modulus. 18. Acoustic device according to any one of claims 1 to 17, in which a piston type acoustic transducer is installed at a location for a flexural vibration transducer producing said acoustic action. 19. The acoustic device according to claim 18, in which the acoustic transducer produces bending vibrations and has a piston effect. 20. The excitation unit of the acoustic device described in any one of claims 1 to 19, comprising a chassis, a chassis-supported transducer coupled to a panel-like element, an elastic edge suspension for coupling the panel-like element to the chassis, the transducer being adapted to be applied to the panel-like the element of the piston impact at relatively low frequencies to generate an output sound signal and the formation of bending vibrations of the panel-like element at high sound frequencies, causing resonance panel-like element with the creation of the output audio signal, and the transducer is configured to be installed in the center of mass and / or the geometric center of the panel-shaped element. 21. The excitation unit according to claim 20, in which the panel-shaped element has a round or elliptical shape. 22. The excitation unit in claim 20 or 21, in which the panel-shaped element contains a lightweight honeycomb core enclosed between opposing outer layers. 23. The excitation unit according to claim 22, in which one of the outer layers of the core protrudes beyond the edge of the panel-like element, the extreme part of this protruding outer layer being attached to the elastic suspension. 24. The excitation unit according to any one of paragraphs. 2023, in which the panel-shaped element is a resonant panel of the distributed mode. 25. The excitation unit according to any one of paragraphs.2024, in which the converter is electromagnetic and comprises a drive coil mounted on a coil frame connected to a panel-like element. 26. The excitation unit of claim 25, comprising a second elastic suspension attached between the coil frame and the chassis. 27. The excitation unit of claim 26, wherein the second elastic suspension is located near the end of the coil frame adjacent to the panel of a different element, and the third elastic suspension is connected between the other end of the coil frame and the chassis. 28. The excitation unit according to any one of paragraphs.2527, in which the end of the coil frame, adjacent to the panel-like element, is attached to act on this element at substantially one point. 29. The excitation unit according to claim 28, comprising a conical means attached between the coil frame and the panel-like element. 30. A loudspeaker containing an acoustic device according to any one of paragraphs. 1-19 and block excitation according to any one of paragraphs.20-29. 31. Panel-shaped element of the loudspeaker excitation unit, made in the form of a rigid lightweight panel, adapted to apply to it the piston action and bending vibrations causing resonance, with the center of mass of the panel-like element coinciding with its geometric center, and the center of distribution of rigidity is offset from the center of mass. 32. An acoustic device according to any one of claims 1 to 19, in which said element comprises a flexural vibration transducer for generating an acoustic effect, installed at a location determined by the spatial distribution of flexural rigidity. 33. The loudspeaker of claim 30, wherein the excitation unit comprises elastic and rigid parts imparting a stimulating effect, for exerting a piston action with axial centering and for providing a panel-shaped element that is offset from the center of resonant excitation. 34. The loudspeaker of claim 33, in which the elastic part is adapted to provide a piston impact on the panel-like element at low frequencies, and at least one rigid part provides resonant excitation shifted from the center at high frequencies. 35. The loudspeaker according to claim 33 or 34, in which the excitation unit is attached to the panel-like element and causes an acoustic effect of the distributed mode in the panel-like element at least at high frequencies by means of at least one said rigid part. 36. Loudspeaker according to any one of paragraphs.33- 35, in which the rigid part (s) are also involved in exerting a piston action. 37. Loudspeaker according to any one of paragraphs.33- 36, wherein said portions are end peripheral portions of the tubular member. 38. The loudspeaker according to clause 37, in which the tubular element is attached to the panel-like element. 39. A method of manufacturing a panel element of an acoustic device according to any one of claims 1 to 19, wherein a nominal location of a flexural vibration transducer is determined in the absence of a change in flexural rigidity, and the zonal distribution of flexural rigidity is adjusted for an element having flexural stiffness variations to offset the nominal transducer location flexural vibrations to the desired location by providing greater and lesser flexural rigidity from different sides of the said desired actual location, as well as from different sides of said nominal location. 40. The method according to claim 39, wherein the greater and lower bending stiffnesses are located along the continuations of a straight line passing through said desired and nominal locations. 41. The method according to claim 39 or 40, according to which overlaying as a control configuration of a panel element is a configuration of a panel element that is known as effective and for which a similar analysis is available, and ensure that the desired control location of the converter matches the actual preferred effective location of the converter on object geometry. 42. The method according to paragraph 41, wherein said known configuration is constructed by extending from a certain edge (s) of the actual disadvantageous configuration. 43. The method according to paragraph 41 or 42, wherein the flexural rigidity distribution is selected based on a compromise between the standard and object configuration so that the known easily analyzed flexural rigidity of the panel's object structure is transformed relative to the standard configuration, with the possibility of obtaining essentially the same, or similar, or gradation-comparable distribution of stiffness, as in object geometry, with the specified transformation including a fourth power for bending estkosti itself and other desired degree determining parameters such as thickness of monolithic structure element or core element layered structure, or outer layer (s) of the latter, or Young's modulus.