CZ57598A3 - Vibration converter - Google Patents

Abstract

A vibration transducer (9) to vibrate a member (2) having a face, characterised by a motor coil assembly having a coil (13) rigidly fixed to a tubular member (18), the assembly being adapted to be fixed to the said face of the member, and by a magnet assembly (15) comprising opposed disc-like pole pieces, the periphery of one of which pole pieces is arranged to be disposed with and adjacent to the motor coil assembly, and the periphery of the other of which pole pieces is formed with a surround flange (90) adapted to surrounding and to be disposed adjacent to the motor coil assembly, and characterised in that the magnet assembly is adapted to be secured at its centre to the said member to be vibrated.

Description

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 an 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 vibrations 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 in acoustic vibration activity therein and on signals, usually electrical, that correspond to the acoustic level of such vibration activity. In co-pending international patent application WO97 / 09842 having the same priority, said elements are proposed for passive acoustic devices without transducer means, such as reverberation or acoustic filtering or acoustic sounding of a room or room, as well as active acoustic devices with transducer 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.

The subject of the invention is a vibration transducer for driving an element having a face, the ability to not dampen and propagate the input vibration energy by bending waves in at least one functional surface extending transversely to its thickness so as to have resonant modes of bending wave vibrations distributed over all a predetermined preferred position in said area for the transducer means, and a transducer mounted on said element in one said position to vibrate the element to achieve resonance of the acoustic radiator element providing acoustic power during resonance thereof, said transducer comprising a motor coil assembly having a coil attached to the tubular member and adapted to be attached to said face of said element, and a magnet assembly having opposing disc pole pieces, the edge of one of the pole pieces being disposed provided within the motor coil assembly and at a location adjacent to the motor coil assembly, and an edge of the second pole piece is formed by a surrounding flange adapted to surround the motor coil assembly and disposed adjacent the motor coil assembly, said magnet assembly adapted to be mounted at its center to said element to vibrate. An attachment means may be provided to attach the magnet assembly to said element. The fastening means may comprise a fastening member adapted to engage in a cavity in said element. The fastening member may comprise a spacer for offsetting the edges of the pole pieces from the element. The vibration transducer may comprise a complementary motor coil assembly / magnet assembly, the parts of which are adapted to be mounted on opposite faces of said element and means for attaching the centers of the magnet assemblies to the two-stroke operation to each other. Thus, said fastening member may have, at opposite ends, a head adapted to engage respective magnet assemblies, the fastening member further comprising a pair of interlocking portions, one of which is formed by a threaded projection and the other by a threaded recess, and a spacer adapted to be disposed adjacent. to said attachment means and adapted to be interposed between respective magnet assemblies and opposing faces of said element.

According to another aspect, the invention is a loudspeaker characterized by 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 modes of bending wave vibrations distributed over said at least one surface and predetermined positions in said and a vibration transducer mounted on said element in one of said positions to vibrate the resonance causing element of the acoustic radiator element, which provides an acoustic output during its resonance.

Brief description of the pictures

For a better understanding of the invention, exemplary embodiments of the invention are illustrated in the accompanying drawings, in which:

Fig. 1 shows a distributed mode loudspeaker as described in related application WO97 / 09842; Fig. 2a shows a partial section taken along line AA in Fig. 1; Fig. 2b shows an enlarged cross-section of a distributed mode emitter of the type shown in Fig. 2a showing two alternative designs of the emitter.

FIG according to the invention and cross-section first converter design Fig. 4 shows the invention. cross-section second design of the converter DETAILED DESCRIPTION OF THE INVENTION FIG of the same type as described panel loudspeaker (81) and claimed in related

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 distributed-mode sound radiating panel (2). 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 induce bending waves 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 rating of 20 to 80 W. If the core of the panel and / or its sheath are made of metallic material, it serves as heat dissipation for the inverter to remove 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 apparent 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 can be seen from Figure 2b that the panel (2) is formed by a rigid light panel having a core (22). made of, for example, a rigid plastic foam (97), such as a cross-linked polyvinyl chloride, or a core (98) with a cellular structure, such as a honeycomb core made of a metal or other similar material, the structures extend transversely to the panel surface and are 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.

The envisaged sheathing materials and reinforcements thus include carbon, glass, Kevlar (RTM), Nomex (RTM), i.e., carbon, glass, cladding, cladding, cladding, cladding, cladding, cladding, cladding, cladding, cladding and cladding. 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 polymer thermoplastics, it has been found that polymer thermoplastics can be used for injection molding of ultra-thin coatings of small size, i.e. about 30 cm in diameter. This material itself forms an oriented crystalline structure in the injection direction, which is the preferred 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., excitation coil and / or 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 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 region.

The hinge 3 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 may be made of a 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 largely non-directional, the percentage of phase-related information off-axis increases. To enhance 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 optimum 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 actually dispersed nature of the acoustic panel acoustic radiation, 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 one embodiment of a transducer (9) for driving bending waves in a rigid light emitting panel (2) of a distributed mode, e.g. a panel of the same type as shown in FIGS. 1 and 2, said panel comprising a core (22) closed by opposing a housing (21) for causing panel resonance.

The transducer comprises a coil (13) attached, eg by means of adhesive means, to the outside of the coil frame (18) which is firmly connected to the surface of the sheath (21) of the radiating panel (2), eg by epoxy adhesive joints (16). The magnet (15) is surrounded by a pair of pole pieces (14), one of which has the shape of a disc, the edge of which is close to the inner part of the coil frame (18), and the other has the form of a flange (90). .

The magnet assembly comprising the magnet (15) and the pole pieces (14) is attached to the panel (2) by a fastener (93) made, for example, of metal or hard plastic, which fastener extends through a cavity (29) extending through the panel (2). 2). Said fastening means (93) comprises a pair of complementary threaded elements (91,92) each having a head (95), the head (95) of one element (91) of said pair of elements opposing the outer surface of the transducer (9). ) and the head (95) of the second element (92) of said pair of elements acts against a face of the panel (2) on the side of the panel opposite to the side on which the transducer (9) is attached to the panel. In order to offset the transducer (9) from the panel (2), a spacer (127) is inserted between the transducer (9) and the panel (2).

In order to induce bending waves in the panel (2) to cause resonance thereof when an acoustic signal is applied to the transducer (9), the transducer (9) shown in Fig. 3 operates such that local elastic bending occurs in the region between the mounting means and coil former (18).

The embodiment of the transducer (9) shown in Figure 4 is similar to the transducer (9) shown in Figure 3, except that in this embodiment the transducer comprises complementary double-acting exciters of the same type as shown in Figure 3 and arranged on opposite sides of the panel. To attach the two transducers together and to the transducers to the panel, a fastener (93) extends through an opening (29) formed in the panel (2). The fastener (93) comprises two opposing complementary portions (94, 96), each having a head (95) which acts against the outer surface of the respective transducer (9) to couple said drivers together. In order to secure the complementary parts (94, 96) together, the two parts are provided with threaded means, e.g. threaded vibrations. Said fastener (93) may be made of any suitable material such as plastic or metal.

In this embodiment, the transducer device (9) is firmly clamped to the panel (2) by means of rigid washers (19) made, for example, of rigid plastic and arranged between the panel and the pole pieces (14) at a location adjacent to the opening (29). thereby causing the local elastic bending of the panel in the region between the washers (19) and the coil frame (18) during operation of the converter, causing the bending wave in the panel to be excited.

Claims (7)

PATENT CLAIMS A vibration transducer (9) for actuating an element (2) having a front surface, capable of not attenuating and propagating input vibration energy by bending waves in at least one functional surface extending transversely to its thickness so as to have resonant modes of bending vibration distributed over said at least one surface and predetermined preferred positions within said surface for the transducer means, and a transducer mounted on said element at one of said positions for vibration of the element to achieve vibration of the acoustic radiator element providing an acoustic output during resonance thereof; comprising a motor coil assembly (13, 18) having a coil (13) fixedly attached to the tubular member (18), the assembly adapted to be attached to said face of the member (2), and a magnet assembly (15) having opposing the disc pole pieces (14), the edge of one said pole pieces being disposed within said motor coil assembly and at a location adjacent said motor coil assembly, and an edge of said second pole piece forming a surrounding flange (90) adapted to surround said motor coil assembly and arrangement at a location adjacent said motor coil assembly, said magnet assembly being adapted to be attached at its center to said element (2) to be vibrated. Vibration transducer according to claim 1, characterized in that it comprises fastening means (93) for fastening the magnet assembly (15) to the element (2). Vibration transducer according to claim 2, characterized in that said fastening means a fastening member (91, 92) adapted to engage formed in the element (2). (93) includes in the cavity (29) The vibratory transducer of claim 3, wherein said attachment member is a spacer (127) for spacing the edges (14) from said element (2). the marked (91, 92) includes pole pieces Vibration transducer according to any one of the preceding claims, characterized in that it comprises a pair of complementary systems comprising a motor coil assembly (13, 18) and a magnet assembly (15) and adapted to be mounted on opposite faces of said element (2), and a means ( 93) for rigidly interconnecting the centers of the magnet assemblies (15) to achieve double-acting operation of the vibratory converter. The vibration transducer of claim 5, wherein said attachment member (91, 92) has heads at opposite ends of said head (95) and is adapted to engage a respective magnet assembly, said attachment member (91, 92) comprising complementary portions (94, 96), which are threaded and engaged with each other, and a spacer (19) adapted to be disposed adjacent to said attachment member and interposed between the respective magnet assembly and opposite faces of said element (2). A loudspeaker (81) comprising an element (2) having the ability to dampen and propagate input vibration energy by bending waves in at least one functional surface extending transversely to the thickness of the element so as to have resonant modes of bending vibration distributed over said at least one surface and predetermined preferred positions within said surface for the transducer means, and a vibration transducer (9) according to the preceding claims mounted on said element (2) in one said vibration position of the element (2) to achieve resonance of the radiator element which provides an acoustic output during its resonance.