CZ57698A3 - Loudspeaker containing panel acoustic radiating elements - 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

Technical field

The invention relates to a loudspeaker and more particularly to a loudspeaker comprising acoustic radiating elements.

BACKGROUND OF THE INVENTION

GB-A-2262861 discloses a panel loudspeaker comprising a resonant multi-mode radiator consisting of a uniform composite plate comprising a core having a transverse cellular structure, wherein the plate has a bending ratio surrounding two shells, strength (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.

Loudspeakers with standard modular form have a wide field of application regarding audio distribution. These include, for example, loudspeakers that are interchangeable with commercial ceiling tiles and typically have an area of 600 x 600 mm. The aim of these speakers is to achieve an even distribution of clearly understandable speech and music across their entire area. Some conventional voice coil drivers and their panel derivatives are the basis for the subject matter of this application.

Existing technologies use conical voice coil loudspeakers mounted in frames and acoustic baffles. Although these speakers are usually used because of their low purchase price and easy availability, they have drawbacks known as hot spots (eg spots with f r ·

• Excessive sound intensity) and directional effects, and as a result less comprehensibility in places outside their axes.

Other technologies use conical loudspeakers in which the conical element has a polystyrene structure with a flat front surface that can be colored. Combining additional exciters with a voice coil adapted to their diaphragm, which is structured to acoustically provide conventional foam shrinkage shock absorbers with increasing frequency, can produce a wider radiation pattern than cone speakers. These polystyrene loudspeaker units require a frame and an acoustic one to attach them to the desired position.

US-A-4,506,117 discloses a suspended ceiling panel provided with an electroacoustic transducer having a metal base plate by which the transducer is attached to said panel.

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 r * f ·

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I- · · * electrical, which correspond to the acoustic measure 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 or acoustic filtration or acoustic room or room acoustic devices, as well as active acoustic devices with sound transducers, 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 for use in suspended ceiling cladding panels.

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 An object of the present invention is a suspended ceiling panel comprising a loudspeaker, the panel comprising an element having the ability to dampen and propagate input vibration energy by bending waves in at least one functional surface extending transversely to its thickness. one surface and a predetermined preferred position in said surface for the transducer means, and a transducer mounted wholly and exclusively on said element in one of said positions for vibration of said element to achieve resonance of the acoustic radiator element providing acoustic power during its resonance '. Said suspended ceiling panel may comprise an element comprising a cellular core made of, for example, a foamed plastic, and a coated module of high modules. In order to support the radiator in a suspended ceiling frame, an edge can also be provided at the edge of the radiator.

Λ Γ Γ e pruž pruž pruž pruž pruž pruž pruž ný pruž ný pruž pruž pruž ný ný ný ný ný Said transducer may comprise an inertial vibration transducer.

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 along the line Ά-Α in Fig. 1; Fig. 2b shows an enlarged cross-section of a distributed mode emitter of the type shown in Figs. Fig. 2a shows two alternative designs of the emitter, Fig. 3a shows a perspective view of a room having a suspended ceiling, and Fig. 3b shows a cross-section of an embodiment of a distributed mode loudspeaker according to the invention in the form of a ceiling cladding.

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 described in detail in related patent applications WO / 09859, WO97 / 09861, WO97 / 09858 with the same priority, is mounted entirely and exclusively on the panel (2) or in the panel (2) at a predetermined a position defined by the x and y coordinates, 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). The amplifier load and power requirements can be conical 8 8 d3 / W at amplifiers quite normal, ie. as with conventional loudspeakers, the sensitivity being of the order of magnitude of the room temperature. Impedance of very resistive character at both 5 and 20 to 80 W. If the core of its panel is made of metallic material, then

And and / or serve as heat dissipation for the inverter to remove heat from the inverter's motor coil, thereby improving 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). using 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.

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 a metal foil, plastic or other similar material, the cells of said structure extending transversely to the panel surface and closed by opposing shells (21) made of a material such as eg 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 sheathing materials and reinforcements include carbon, glass, Kevlar (RTM), Nomex (RTM), i. 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 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., 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 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.

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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 flexible or rigid polymeric sheet material. Some materials, especially paper and board, and some types of core materials may be self-attenuating. 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, in particular in terms of multiple minor effects and / or middle and higher frequencies, may be accomplished by means of a suitable mass or masses attached.

to sheet material in center positions in said advance desktop. set effective The above panel is really two-dimensional. Audio

the 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 loved one.

speaker, and consequently, which is the second of these drawbacks, in a reduced perception of the volume of the other speakers.

Also, the additional speaker quality and its requirement is a visual benefit only on the speaker range for flat light attractiveness, panel sound good requires no every panel diagram.

one inverter, a switch for taking this whole sonic

Giant. 3 illustrates a ceiling cladding panel 36 adapted to be supported in a hinged hinged frame 99 to form a suspended ceiling, which panel is in the form of a loudspeaker 81 generally of the type described with reference to FIGS. 1 and 2, i.e., the loudspeaker comprises a rigid light multimode a resonant panel 2 having a core 22 coated on both sides of the sheath 21. The panel 2 is mounted at its edges to resilient foam rubber hinges 3 which are supported on the frame 99. The hinge 2 may be attached either to the panel 2 or to the frame 99 by means of adhesive means, but the connection may be achieved by the weight of the resonant panel 2 itself. This panel 2 carries a transducer 9, such as the transducer described in connection with Figs. 12, to excite the bending waveform in the panel to achieve its resonance and produce an acoustic output. The transducer 9 may have a position on the panel as described in related international application WO97 / 09842.

In a preferred good quality embodiment, said panel 2 is made of a foamed polystyrene core typically having a density of 100 g / m ³ and a thickness of 8 mm, the core being coated with a 0.1 mm thick hardened aluminum alloy sheath. A 3 mm thick foam or felt strip is attached to the perimeter of the panel 2 to provide a partially flexible attachment of the panel when the panel is placed in said ceiling frames, and also helps to suppress any vibration in the sections of the ceiling frame.

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The exciter of said panel is preferably a flywheel panel with a unit voice coil having a diameter of 25 mm or 38 mm, an impedance of 6 Ω, a load rating of 40 W, the voice coil being directly connected to the panel surface. A compact cap-like magnet system and an automatic seal can also be directly connected to said panel by means of a flexible damping ring chosen for its vibration-mechanical properties and dimensional stability.

Depending on the application, an inexpensive ceiling cladding panel may be produced comprising a paper-coated foamed plastic core, which may have a light alloy foil layer to provide fire-resistance to the panel, and may be excited by inexpensive piezoelectric exciters. With the board, the maximum level limit is achieved, which is more than sufficient for personnel announcements, spoken comments and background music. In addition, a wide area coverage is maintained.

If metal or carbon conductive shells or cores are used for said cladding boards, then the loudspeakers can be grounded to maintain the electromagnetic shielding of the installed structure.

Industrial applicability

The loudspeaker in the form of a ceiling plate according to the invention does not require a frame or acoustic dampers. The entire loudspeaker panel is of uniform size and can only be placed in the desired position as a passive decorative ceiling cladding. The acoustic panel is relatively lightweight and therefore does not significantly burden the ceiling construction and simplifies the installation of the ceiling formed by these panels. It is also possible to make this panel fireproof. In addition, the acoustic panel may be decorated, painted or wallpapered so that the panel becomes

visually inconspicuous without deteriorating the acoustic properties of the panel.

In addition, minor damage to this panel does not reduce panel performance compared to diaphragm and conical speakers that are not very resistant to damage. Also a great advantage of this acoustic panel is its sound distribution. The high degree of clarity, together with the wide coverage angle of this panel, means that in a typical large-area installation, it is possible to achieve excellent sound power using only half the number of panels relative to the number of conventional speakers, thereby significantly reducing installation costs.

Claims (5)

PATENT CLAIMS A suspended ceiling cladding panel (36) comprising a loudspeaker (81), characterized in that it comprises an element (2) that is capable of not attenuating and propagating the input vibration energy by bending waves in at least one functional area extending transversely to its thickness. 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 (9) mounted entirely and exclusively on said element in one of said vibration positions of said element to achieve resonance of the acoustic element an emitter that provides an acoustic output during its resonance. A suspended ceiling cladding panel according to claim 1, characterized in that said element (2) comprises a chamber core (22) coated with a high modulus sheath (21). The suspended ceiling panel according to claim 1 or 2, further comprising a resilient hinge (3) disposed at the edge of the emitter (2) for supporting the emitter in the suspended ceiling frame (99). The suspended ceiling cladding panel according to claim 2 or 3, if this claim is dependent on claim 2, characterized in that said chamber core (2) is made of a foamed plastic (97). Suspended ceiling cladding panel according to one of the preceding claims, characterized in that said transducer (9) is formed by an inertial vibration transducer.