CZ57398A3 - Inertial vibration converter - Google Patents

Abstract

An inertial vibration transducer (9) characterised by a motor coil assembly comprising a tubular member (18) and a coil (13) rigidly fixed to the tubular member, and by a magnet assembly (15) disposed concentrically within the motor coil, and resilient means (19) supporting the magnet assembly for axial movement relative to the motor coil, the motor coil and tubular member being adapted to be rigidly mounted to a distributed mode radiator (2).

Description

Inertial vibration converter

Technical field

The invention relates to a transducer, in particular a vibrating transducer for loudspeakers comprising panel acoustic radiating elements.

BACKGROUND OF THE INVENTION

GB-A-2262861 discloses a panel loudspeaker comprising a resonant multimode emitter consisting of a uniform composite plate comprising a cross-chamber core core that surrounds two shells, the plate having a bending strength ratio (b) in all directions to a cubic power of panel weight per unit area (μ) equal to at least 10, a fastener carrying or supporting said plate to the support body in a free, non-attenuated manner, and electromechanical excitation means designed to drive multi-mode resonance in the radiating plate in response to an electrical input within the working frequency range for the speakers.

US-A-4,506,117 discloses an electroacoustic transducer comprising an inertial mass adapted to be attached to a base plate of a panel to be vibrated.

SUMMARY OF THE INVENTION

Individual embodiments of the invention use elements having properties, eg, structure and configuration, generally and / or specifically described in WO 97/09842 relating to this application. Therefore, these elements have the ability not to dampen and propagate the input vibration energy by bending waves in the functional area or functional areas that extend transversely to the thickness of the element often but not necessarily to the edges of said element or elements having configuration with or without anisotropy of bending strength. resonant modes of bending wave vibration distributed over the entire surface of the element in a favorable manner for acoustic communication with ambient air, and having predetermined advantageous positions on said surface for the transducer means, in particular for functionally active or movable parts thereof effective with acoustic vibration activity therein and on signals, usually electrical, that correspond to the acoustic level of such vibration activity. In the related international patent application WO97 / 09842 having the same priority, said elements are proposed for passive acoustic devices without transducer means, such as reverberation devices or acoustic filtration or acoustic sounding of a room or room, as well as active acoustic devices with converter means, including sound sources or loudspeakers with a remarkably wide frequency range where input signals are applied to said sound, or microphones that are exposed to sound which they convert to other signals.

In particular, the invention relates to active acoustic devices in the form of loudspeakers. The above elements in these devices are referred to as distributed mode acoustic radiators and have the characteristics described in patent application WO 97/09842 or other characteristics described in this patent application.

SUMMARY OF THE INVENTION The present invention provides an inertial vibration transducer for generating an element having the ability not to dampen and propagate input vibration energy by bending waves in at least one functional surface extending transversely to its thickness so as to have resonant bending-vibration modes distributed over said at least one surface and predetermined a preferred position within said transducer means surface, and a transducer mounted on said element in one said position to vibrate said element to achieve resonance of said acoustic radiator element which provides acoustic output during its resonance, said inertial vibration transducer comprising a motor coil assembly having a coil attached to the tubular member, a magnet assembly disposed concentrically with respect to the motor coil assembly, and resilient means for supporting the magnet assembly to achieve axial movement of the assembly relative to the motor assembly and wherein said tubular element is adapted to be directly attached to said element to vibrate by means of adhesive means. Said resilient means may comprise mutually opposed elastomeric members disposed on opposite sides of said magnet assembly. Caps may be used to close the axial ends of the tubular member to which said resilient means may be attached. These caps may comprise a resilient means. Each of said caps may further comprise an annular resilient flute. In addition, a magnetic shield may be provided over these caps. Said coil may be mounted on the inside of said tubular element. Said motor coil assembly may be adapted to be positioned within a hollow cavity of the emitter having a shape corresponding to that of the assembly. In addition, the motor coil assembly may be adapted to be attached to the face of said radiator. The magnet assembly may comprise opposing generally disc-shaped pole extensions, the edge of one of these extensions being arranged within said motor coil assembly and at a location adjacent to the motor coil assembly and the edge of the other of the pole extensions being a flange disposed adjacent the motor coil assembly and surrounding motor coil assembly. A resilient element may be interposed between one of the pole pieces and the front surface of the emitter. Said magnet assembly may comprise a pair of opposing magnets interposed between said pole pieces. Complementary assemblies, each including a motor coil assembly and a magnet assembly, may be disposed on opposite faces of said emitter, and further provided means for securing the magnet assemblies to each other for dual-action operation.

According to another aspect, the present invention provides a loudspeaker comprising a flywheel converter as described above.

Brief description of the pictures

BRIEF DESCRIPTION OF THE DRAWINGS The invention will become more apparent from the description of exemplary embodiments of the invention, in which reference is made to the accompanying drawings, in which Fig. 1 shows a distributed mode loudspeaker as described and claimed in WO97 / 09842. Fig. 2a shows a partial cross-section along line AA shown in Fig. 1, Fig. 2b shows an enlarged cross-section of a distributed mode emitter of the same kind as shown in Fig. 2a, which also shows two alternative structures of the emitter.

Figure 3 shows a cross-section of the first embodiment of the converter, Figure 4 shows a cross-section of the second embodiment of the converter, Figure 5a shows a cross-section of the third embodiment of the converter, Figure 5b shows a cross-section of the fourth embodiment of the converter; the sixth inverter version.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 shows a panel loudspeaker (81) of the same type as described and claimed in the related application WO97 / O9842 with the same priority, the loudspeaker comprising a rectangular frame (1) carrying a flexible hinge (3) around the inner edge which carries a sound emitting panel (2) with distributed modes. The transducer (9), e.g., the transducer detailed in the related patent applications WO / 09859, WO97 / 09861, WO97 / 09858 with the same priority, is mounted entirely and exclusively on the panel (2) or panel (2) at a predetermined position defined the coordinates x and y, which coordinates are calculated as described in related application WO97 / 09842 with the same priority, to excite the bending waveform in the panel to cause resonance of the panel forming the radiator providing acoustic power during its resonance.

Said transducer (9) is driven by a signal amplifier (10), eg a low-frequency amplifier, connected to said transducer by means of conductors (28). Amplifier loads and power requirements can be quite normal, ie. as in conventional conical loudspeakers, with a sensitivity of the order of 86 to 88 dB / W at ambient load conditions. The impedance load of the amplifier has a very resistive character at 6 20 and a load capacity of 20 to 80 W. If the core of the panel and / or its sheath are made of metal, it serves as heat dissipation for the inverter to dissipate heat from the inverter's motor coil. and hence improve performance.

Figs. 2a and 2b show typical cross-sections of the loudspeaker (81) in Fig. 1. It is clear from Fig. 2a that the frame (1), the flexible hinge (3) and the panel (2) are connected to each other in the connections (20). by means of adhesive means. The frame may be a lightweight frame, e.g., an image extruded frame of a metallic material, e.g., aluminum alloy, or plastic. Suitable materials for said flexible hinge may be flexible materials such as foam rubber and foamed plastic. Suitable adhesives for the joints (20) may be epoxy, acrylate and cyanoacrylate resins or other adhesives.

foils, plastic taking chambers

It is clear from Figure 2b that the panel (2) is formed by a rigid light panel having a core (22) made, for example, of rigid plastic foam (97), such as a cross-linked polyvinyl chloride, or formed by a core (98). with a cellular structure, such as a honeycomb core made of metal or other similar material, said structures extending transversely to the panel surface and closed by opposing shells (21) made of a material such as paper, plastic or metal foil. In case the casings are made of plastic, the casings can be reinforced in a known manner, for example by carbon, glass, Kevlar fibers, etc., to increase their modules.

Thus, the envisaged honeycomb layer materials and reinforcements include carbon, glass, Kevlar (RTM), Nomex (RTM), i.e., " aramid, fibers in different layers and weaves, as well as paper, laminated paper, melamine and various synthetic high-modulus plastic films such as Mylar (RTM), Kaptan (RTM), polycarbonate, phenol, polyester plastic or related plastic materials, fiber reinforced plastics and metal foils. Based on Vectra liquid crystal quality research based on polymeric thermoplastics, it has been found that polymeric thermoplastics can be used for injection molding of ultra-thin coatings of small size, e.g. with a diameter of about 30 cm. This material itself constitutes an oriented crystalline structure in the injection direction, which is an advantageous direction for good propagation of high sound frequencies from the drive point towards the edges of the panel.

The additional molding of said or other thermoplastics allows the molding tools to have localization and registration features. such as grooves or rings for accurately positioning parts of the transducer, e.g., an excitation coil and / or a magnet hinge. In addition, in the case of a weaker core material, it may be advantageous to locally increase the thickness of the sheath, e.g. in a surface or ring with a diameter up to 150% of the sensor diameter, in order to strengthen said surface and advantageously couple the vibration energy in the panel. In this way, the high frequency response can be improved for some softer foam materials.

The envisaged core layer has a honeycomb structure or a corrugated structure formed of aluminum alloy foil, Kevlar (RTM), Nomex (RTM), uncoatable paper or paperboard and sheets of various synthetic plastics, as well as cellular or foamed plastic or fiber materials, even aerogel metals if they have a suitably low density. Some suitable core layer materials have a self-sheathing capability in manufacture and / or have sufficient rigidity to be inserted between the sheath layers without lamination. The material for the core having a highly efficient cellular structure is known under the trade name Rohacell, which material may be suitable for the radiating panel without being provided with a jacket. In practical terms, the aim is to achieve overall lightness and stiffness suitable for specific purposes, which in particular involves optimizing core contributions, sheath layers and transitions therebetween.

In several preferred embodiments of the panel, sheaths of metal and metal alloys are used, or alternatively, the materials are reinforced with carbon fibers. These panel designs, as well as panel designs in which the Aerogel alloy is used or in which the core has a honeycomb structure of metallic material, have a high frequency shielding capability that is important for the compatibility of electromagnetic energy emitting devices. Conventional cone-type panels or loudspeakers do not have the capability of said shielding.

In addition, preferred forms of piezoelectric transducers and electrodynamic transducers have negligible electromagnetic radiation or stray magnetic fields. Conventional loudspeakers have a large magnetic field, up to 1 m away, unless specific compensating countermeasures are taken.

Where it is important to provide or maintain shielding in a given application, the electrical connections may be made such that the conductive portions of a suitable DML panel, the electrically conductive foam or the like interface can be used for attachment in the edge area.

The hinge 2 may damp the edges of the panel 2 to prevent excessive movement of the edges of the panel. In addition, additional damping means may be used, e.g., patch-like means associated with the panel at selected positions to damp excessive movement of the panel to achieve a uniform resonance distribution across the panel surface. These patches can be made of bitumen-based material typically used in conventional loudspeaker enclosures, or a resilient or rigid polymeric sheet material. Some materials, especially paper and board, and some types of core materials may be self-dimming. If desired, damping in the construction of the panels can be enhanced by the use of adhesives that are flexible and not stiff after curing.

Said effective selective damping comprises specific panel applications comprising the sheet material of the device permanently associated with the panel. The edges and corners may be particularly important for the dominant and less dispersible low frequency modes of bending vibration of the panel described in this application. The edge fastening of the damping means may advantageously lead to a panel with a completely framed sheet material, although at least its corners may often be relatively free for desirable elongation of the panel in low frequency panel operation. Said attachment may be by means of adhesive or self-adhesive materials. Other forms of useful damping, particularly with respect to multiple minor effects and / or mid and high frequencies, may be accomplished by means of a suitable mass or masses attached to the sheet material at predetermined effective center positions within said area.

The above panel is indeed two-dimensional. The sound energy from the rear of the panel is not strongly phase related to the sound energy from the front of the panel. This brings the advantage of the total sum of the acoustic power in a given space, the sound energy of uniform frequency distribution, the limited effect of reflecting and standing waves and good reproduction of natural space.

While the sound or radiation from the acoustic panel is considerably non-directional, the percentage of phase-related information off-axis increases. To improve the focus of artificial stereo listening, positioning the speaker at a height at which images are usually hung, that is, at the normal height of a standing person, gives the normal seated listener optimal stereo listening even when in a slightly deviated position speaker. Similarly, this triangular geometry left / right relative to the listener provides an additional angular component. In this way a good stereo effect is achieved.

This is another advantage for the group of listeners compared to conventional loudspeaker reproduction. Due to the actual diffuse nature of the acoustic radiation of the acoustic panel, the acoustic panel provides an acoustic volume which is not in any way subject to the square decrement rule for the equivalent point source. As a result, for listeners sitting off the loudspeaker axes or at a location not very suitable for listening, the field strength of the panel loudspeaker promotes a better stereo effect compared to conventional loudspeakers. This is because the listener located outside the center of action of all speakers does not suffer from two drawbacks, which are usually applied near the speakers. The first of these drawbacks lies in the excessively increased perceived loudness of the proximal speaker and, consequently, the second of these shortcomings, in the reduced perception of the loudness of the other speakers.

Also, another advantage of the flat light panel loudspeaker is its visual attractiveness, good sound quality and the requirement for only one transducer, and this loudspeaker does not require a crossover for the entire sound range for each panel diagram.

Giant. 3 shows an embodiment of an inverter 9 with a voice coil completely disposed within a rigid distributed mode panel 2 comprising a core 22 coated on both sides of the jacket (21) to induce bending waves in the panel 2.

The transducer comprises a coil 13 embedded in a fastener 16 made, for example, of epoxy resin, and arranged in a cavity 29 in the core 22 of the panel 2, and surrounding the cylindrical coil frame 18, the coil 13 and its frame 18 being mounted in the panel 2.

In the portion of the cavity 29 defined by the coil former 18, a magnet assembly is mounted which includes a pair of opposing magnets 15 separated by a pole element 14 and is attached to the inside of the panel shells 21 by opposing flexible hinges 19 made of a rubber material such as foam rubber. and adhesively connected to the magnet assembly and the inner surfaces of the respective shells 21 of the panel 2. The magnet assembly 14, 15 is therefore concentrically disposed relative to the coil 13 and movable in the axial direction on the hinges 19 of the assembly.

During operation of the inverter, due to the axial movement of the magnet assembly relative to the coil, there is local elastic deformation of the panel in the region between the magnet assembly and the coil, and thus excitation of bending waves in the panel.

In operation of the transducer, at least at high frequencies, due to the mass of the magnet assembly being relatively greater compared to the mass of the panel, the inertia of the magnet assembly tends to keep the magnet assembly in a stationary state and keep the panel relative to the magnet assembly in a vibrating state.

Giant. 4 shows another embodiment of a transducer 9 with a voice coil similar to that shown in FIG. 3 and disposed entirely within the inner portion of the rigid light emitting panel (2) comprising a core 22 coated with a sheath 21 to induce bending waves therein. Inverter 2 with panel 2. This converter takes the form of a modular assembly. As can be seen from this figure, a suitable cavity 120 is formed in the panel 2 for receiving the transducer 9. ·

Said transducer comprises a coil 13 secured to the inner wall of the cylindrical coil frame 18 by means of, for example, a rigid adhesive casting 20, wherein the coil frame 18 provides an outer housing of the transducer and is closed at opposite axial ends with light end caps 119 which are secured to the coil frame by any desired by means of, e.g., adhesive bonds 220.

The transducer module assembly is adapted to be placed in the cavity 120 in the distributed mode panel 2 by moving in the direction of arrow A. This transducer assembly is secured in the cavity by adhesives.

A magnetic assembly comprising a pair of opposing magnets 15 separated by a pole element 14 is mounted in the cavity 29 defined by the bobbin body 18, and is mounted on the end caps 119 of the bobbin 18 by opposing elastic hinges 19 made of a rubber material such as foam rubber, and adhesively bonded to the magnet assembly and the inner surfaces of the respective end caps.

Thus, the magnet assembly 14, 15 is mounted concentrically with respect to the coil 13 and is axially movable on its hinge 19. During operation of the transducer 9, a local elastic deformation of the panel and hence vibration of the panel occurs, as is the case of the transducer shown in FIG. so that the inverter drives bending waves in panel 2.

In the embodiment of Fig. 5a, the transducer 9 comprises complementary double-acting drivers located on opposite sides of the panel 2 to induce bending waves in a rigid light mode distributed mode light emitter 2 comprising a core 22 surrounded by opposite shells 21 to cause panel resonance.

In this embodiment, the coils 13 are attached, e.g., by adhesives, to the outside of the coil former 18 to form motor coil assemblies that are rigidly connected, e.g., epoxy adhesive joints 16, to opposite surfaces of the sheaths 21 of the radiating panel 2. The magnets 15 are closed a pair of poles 14, one of which is disc-shaped and has an edge close to the inner portion of each coil former 18, and the other has a peripheral flange 162 arranged to surround the coil 13.

The fastener 93, which is generally cylindrical in shape, is arranged such that it freely extends through an opening 29 in the panel 2. This. the fastening element 93 comprises opposing generally complementary portions, each provided with a head 95 which acts against the axial end of the respective exciter of said pair of transducers of the transducer 9 to couple the exciters together. Said complementary portions of the fastener 93 are rigidly connected to each other by complementary threaded portions 160, 161. The fastener may be made of any suitable material, such as plastic.

In the embodiment of Fig. 5a, the panel 2 is not firmly clamped to the panel 2 at a location adjacent to the opening 29, but is coupled to the panel through resilient pads 17 made, for example, of foam rubber, and arranged near the opening 29 in the panel 2 3 and 4, whereby the transducer 9, due to the inertial effects induced by the combined mass of the respective exciters, drives bending waves in the panel 2.

The embodiment of the transducer 9 in Fig. 5b is generally similar to the embodiment of Fig. 5a except that in the embodiment of Fig. 5b, the transducer 9 is intended to be mounted on only one side of the panel 2. The magnet assembly 14, 15 is therefore fixed to the surface panel

2. by means of a resilient hinge 17 made, for example, of rubber, and attached to the edge of the flange 162 of the outer pole piece 14.

Giant. 5c shows an embodiment of a transducer 9 of the same type as shown in FIG. 5b and intended to be simply applied to the panel surface. The transducer 9 is therefore fixed by means of a coil frame 18 and a resilient hinge 17 on a thin substrate 147 provided with a self-adhesive layer on the outside by means of which the transducer can be fixed to the panel 2 in the desired position.

The transducer 9 in FIG. 6 is a low profile device and can be substantially concealed within the distributed mode panel 2. The transducer comprises a coil cylindrical body 18 adapted to be secured, e.g., with adhesives, in a corresponding aperture 29 in the panel 2. In order to form a motor coil assembly, a coil 13 is secured to the inside of said framework 18 with an opposing axial the ends of the carcass 18 are closed by disc-shaped resilient hinges 59 made, for example, of rubber and other similar materials, and provided with an annular groove 136 disposed at the edge of said hinges to form a ridge-like edge used with conventional conical loudspeaker drivers. The edges of said hinges 59 are secured to the axial ends of the carcass 18, e.g. by snapping the respective parts of these elements by means of adhesives or some other suitable means. The central portions of the hinges 59, which are defined by said annular grooves 136, carry between them a magnet assembly comprising a pair of opposing magnets 15 between which a pole piece 14 is inserted. The outer faces of the magnets 15 are attached to the central portions of the hinges 59, as a result of which the magnet assembly 14, 15 is disposed concentrically relative to the coil 13 and is capable of limited axial movement relative to the coil 13.

The magnet assembly is shielded by disc-shaped shields 121 mounted on annular resilient members 17 supported on the panel 2 to prevent or reduce the scattering magnetic field surrounding the panel at a location adjacent to said transducer.

Although in the above embodiments of the transducer, the motor coil assembly is shown attached to the panel 2 and the magnet assembly shown to be resiliently attached to the panel, it will be appreciated that this arrangement can be reversed such that the magnet assembly is attached to the panel. said panel and the motor coil assembly is resiliently suspended.

In this case, the magnet assembly will be made to be relatively light, and the motor coil assembly will be made to be relatively heavy to increase the excitation effect.

Claims (14)

PATENT CLAIMS An inertia vibration transducer (9) for actuating an element (2) having the ability not to dampen and propagate the input vibration energy by bending waves in at least one functional surface extending transversely to the thickness so as to have resonant modes of bending vibration distributed over said at least one surface; a predetermined position within said area for the transducer means (9), and a transducer mounted on said element in one of said positions for vibration of said element to achieve resonance of the acoustic radiator element providing an acoustic output during resonance thereof, comprising a motor coil assembly (13, 18) having a coil (13) attached to the tubular element (18), a magnet assembly (15) concentric to the motor coil assembly, and a resilient means (19, 136) supporting the magnet assembly for axially moving the magnet assemblies relative to the motor coil assembly, wherein the tubular member (18) is adapted to be directly attached to the member (2) to be vibrated by the adhesive means (16, 20). An inertia vibratory transducer according to claim 1, characterized in that said resilient means (19, 136) comprises mutually opposed elastomeric elements arranged on opposite sides of said magnet assembly. An inertia vibratory transducer according to claim 1 or 2, characterized in that it comprises caps (59, 119) closing the axial ends of the tubular element (18), said resilient means (19, 136) being mounted on said caps. . An inertia vibratory transducer according to any one of claims 1 to 3, characterized in that the coil (13) is mounted on the inside of the tubular element (18). An inertia vibratory transducer according to any one of the preceding claims, characterized in that the motor coil assembly (13, 18) is adapted to be inserted into a cavity (120) in the emitter (2) having a shape corresponding to the shape of the assembly. An inertia vibratory transducer according to claim 3, 4 or 5, if the claim is dependent on claim 3, characterized in that said caps (59) comprise resilient means (136). The inertia vibratory transducer of claim 6, wherein each of said lids (59) comprises an annular resilient flute (136). An inertia vibratory transducer according to claim 6 or 7, characterized in that it comprises magnetic shields (121) arranged over said caps (59). An inertia vibratory transducer according to any one of claims 1 to 4, characterized in that the motor coil assembly (13, 18) is adapted to be fastened to the face of the radiator (2). An inertia vibratory transducer according to claim 9, characterized in that the magnet assembly (15) comprises opposed generally disc-shaped pole pieces (14), the edge of one of these pole pieces being located within the motor coil assembly (13, 18) and within the motor coil assembly. and the edge of the other of the pole pieces is formed by a flange (162) located adjacent the motor coil assembly and surrounding the motor coil assembly. An inertia vibration converter according to claim 10, characterized in that a resilient element (17) is interposed between one of the pole pieces and the front surface of the emitter. An inertia vibratory transducer according to any one of claims 1 to 9, characterized in that the magnet assembly (15) comprises a pair of opposing magnets (15) between which a pole piece (14) is inserted. An inertia vibratory transducer according to any one of the preceding claims, characterized in that it comprises two complementary magnet assembly / motor coil assemblies arranged on opposite sides of the emitter and means (93) for attaching the magnet assemblies to each other for dual-action operation. A loudspeaker comprising an inertial transducer according to any one of the preceding claims.