RO119045B1 - Panel-shaped speaker - Google Patents

Abstract

A panel-form loudspeaker (81) having a distributed mode acoustic radiator (2, 4) and a first transducer (9) coupled to the radiator (2) to excite distributed mode resonance in the radiator, characterised by a second transducer (9) coupled to vibrate the radiator (14).

Description

The invention relates to a panel-shaped speaker, such as those provided with radiant acoustic elements.

It is known, from the patent application GB-A-2262861, the solution for making a panel-shaped speaker, comprising:

- a radiant element in various ways, resonant, in the form of sandwich panel, forming a unitary cellular construction consisting of two film layers of a material, separated by a core highlighted by the cross-section of the cell construction, the panel having, independently of steering, a coefficient of resistance to bending (B) equal to the mass of the panel at power 3, per unit of surface (μ), of minimum value 10;

- a mounting device that supports the panel or secures it to a support body, freely and without cushioning;

- an electromechanical actuator device coupled to the panel and which is used to excite the resonant panel, radiant in various modes, in response to the application of an electrical signal corresponding to the working frequency band of the speaker.

Wamaka holder US-A-3247925 discloses a speaker that is intended to be a low frequency resonant panel speaker mounted on a chassis and excited by a chassis-mounted electromechanical transducer.

In order to achieve the present invention, elements of a certain type, structure and configuration are commonly obtained and / or in particular, by applying the knowledge from the publication of PCT patent application WO97 / 09842, the applicant of which is the same as the one of the application. PCT patent which was the basis for opening the national phase of this patent application. Such elements have the capacity to maintain and propagate, by means of flexural waves, vibration energy of entry, in the operational area or zones, which, as a rule, extend transversely on thickness, and not necessarily to the edges of the respective element or elements, being configured with or without anisotropy of flexural stiffness to have resonant type vibration components, advantageously distributed, in the respective or respective areas, for achieving acoustic coupling with the environment, having preferential locations or locations, predetermined, inside in that area, to dispose of a translator in the respective zone (s), in particular in that part or operationally active or mobile part thereof, effective in terms of acoustic vibration activity and in terms of electrical signals, as a rule, appropriate to the content acoustics of such activity v ibraţionale. In the publication of the mentioned PCT patent application WO97 / 09842, the uses of such elements are presented, within devices such as passive acoustic devices without a translator, such as, for example, for reverb, for acoustic filtration or for achieving acoustic harmony. in a space or in a room, and in acoustic devices active with the transducer, such as, for example, those in the very wide range of acoustic or speaker sources, when they are provided with input signals, to be converted respectively into beep, or such as, say, microphones, when exposed to a beep to be converted to another signal.

This invention mainly deals with acoustic devices in the form of loudspeakers. Elements of the above are known, such as, for example, radially distributed radiant elements, the characteristics of which are in accordance with the solution described in the aforementioned PCT patent application and / or in accordance with the specific features of of the invention herein.

The present invention relates mainly to a panel-shaped diffuser having a part comprising a rigid, lightweight panel having the ability to maintain and propagate, through flexural waves, vibrational input energy, in at least one active area which lays down

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R0119045 Β1 transversely on thickness, to have vibrating components of resonant type, distributed over the respective area, and to have preferred or predetermined locations or locations, 50 within that area, for arrangement in one of the respective locations or locations, of a transducer integrally and exclusively mounted, on said radiant element, to determine the vibration of said radiant element, so that it enters the resonance, thus forming an acoustic emitter which generates an acoustic radiation when it resonates. The primary and secondary transducers can be adapted to operate in different 55 frequency ranges. The radiator may have a sandwich core between two outer layers. The diffuser may comprise a frame supporting the radiator, and an elastic suspension through which the radiator is attached to the frame. The frame can be surrounded by the radiator, and the suspension can be attached to the radiator edge. The first and second transducers can be fully and exclusively mounted on the radiator. One of the transducers can be electromagnetic type. One of the transducers can be piezoelectric. The panel-shaped diffuser may comprise a second element having the capacity to maintain and propagate, by means of flexural waves, vibratory input energy, in at least one active area that extends transversely on thickness, to have resonant vibrational components. , distributed over the respective area, and to have preferential locations or locations, predetermined, within that area, for the arrangement in one of those locations or locations, of a translator mounted integrally and exclusively, on said radiant element, to determine the vibration to the radiating element, so that it enters the resonance, thus forming an acoustic emitter which generates acoustic radiation when it resonates, a second piece being mounted on or within the first mentioned piece, elastic suspension means coupling 70 the two parts. The second part can be mounted in a cut of the first piece. The second transducer can be mounted entirely and exclusively on the second part.

The panel-shaped speaker, according to the invention, has the following advantages:

- has a simple, light weight construction, being easy to make;

- it allows to obtain a uniformly distributed sound in terms of frequencies 75 and a higher stereo effect, compared to that of conventional speakers;

- has special properties for shielding radio frequencies and reducing stationary wave effects.

The following is an example of an embodiment of the invention, in connection with FIGS. 1-7, which represents:

- Fig. 1, constructive diagram of a distributed type diffuser, according to the description of the invention in the publication of PCT patent application WO97 / 09842;

FIG. 2a, view through a partial cross-section, following the section line A-A of fig. 1;

- Fig. 2b, view through a cross-section, on an enlarged scale, of a radiant element 85 with distributed operation, of the type of the one in Fig. 2a, presented in two embodiments;

FIG. 3 is a schematic diagram of a loudspeaker operating in a distributed manner, according to a first embodiment of the invention;

FIG. 4 is a schematic diagram of a loudspeaker operating in a distributed manner according to 90 of a second embodiment of the invention

FIG. 5 is a schematic diagram of a loudspeaker operating in a distributed manner, according to a third embodiment of the invention;

- Fig. 6, the constructive diagram of a loudspeaker operating in a distributed manner, according to a fourth embodiment of the invention; 95

- Fig. 7, perspective view of the constructive scheme of a translator.

RO 119045 Β1 in Fig. 1 is presented a speaker 81, in the form of a panel, of the type described in the publication of PCT patent application W097 / 09842, the applicant of which is the same as the one of the PCT patent application that was the basis of the opening. the national phase of the present patent application, the diffuser 81 having a rectangular frame 1, of which some elastic suspension means 3 are arranged, arranged around its internal peripheral contour, which support a radiant element 2, acoustically, in the form panel, distributed type (with distributed operation). A translator 9, for example of the type widely presented in the publications of PCT patent applications WO97 / 09859, WO97 / 09861, WO97 / 09859 having the same date and the same applicant as of the PCT patent application which was the basis for the opening of the national phase of of the present patent application, is integrally and exclusively mounted on, or within, the radiant element 2 in the form of a panel, in a predetermined location, defined by the x and y coordinates, and whose location is calculated according to those presented in the publication of the application PCT patent W097 / 09842, mentioned above, in order to produce, in the panel, a bending wave that causes its resonance to enter, for the purpose of generating an acoustic output emission.

The transducer 9 is controlled by a signal amplifier 10, for example, an audio frequency amplifier connected to the transducer by means of conductors 28. The signal amplifier load 10 and the power requirement may be the normal ones, similar to those of conventional conical speakers, and the sensitivity is of the order of 86 ... 88 dB / watt when used in a furnished room. The load impedance of the signal amplifier 10 is largely resistive, being 6 ohms, which dissipates a power of 20 ... 80 watts. When the core and / or the film layers of the panel are metallic, they can be made to act as a heat radiator of the transducer, to evacuate the heat from the coil of the coil-motor assembly of the transducer and thus improve the energy balance. .

Figure 2a and 2b show partial cross-sections, typical for the speaker 81 of Figure 1. in FIG. 2a shows how the frame 1, the elastic suspension means 3 and the radiant element 1 in the form of a panel, are connected together, using some adhesive jointing means 20. As suitable materials for realizing the frame 1, we mention the light frame-like structures. of panels made of extruded metal, aluminum or plastic alloy. For the elastic suspension means 3 it is advisable to use elastic materials such as, for example, rubber or plastic, both of foam type. As suitable materials for adhesive bonding means 20, we mention epoxy, acrylic, cyanoacrylate adhesives etc.

in FIG. 2b is shown, on a larger scale, the radiant element 2 in the form of a lightweight, rigid panel, comprising a core 22 made of a rigid foam 97, made of plastic, such as, for example, cross-linked polyvinyl chloride, or a cell matrix 98 having a honeycomb structure made of metal foil, plastic or other similar material, and whose cells are arranged transversely, in relation to the plane of the panel, being closed by two opposing film layers 21, made by for example, of paper, cardboard, plastic or of sheets or sheets of metal. When the film layers 21 are made of plastic, for the growth of its (Young) module, they may be fiber reinforced, in a manner known per se, the fibers being, for example, carbon, glass, Kevlar ® or the like.

The materials proposed for the coating and curing film states include carbon, glass, Kevlar ®, Nomex ® meaning aramid fibers, etc., of different structures and textures, such as paper, laminated pressed paper, melamine and various mass films. high modulus (Young) synthetic plastics, such as Mylar ®, Kaptan ®, polycarbonate, phenol, polyester or associated plastics, and reinforced plastics with

R0119045 Β1 fiber etc. and sheets and sheets of metal. The studies and researches carried out on the Vectra class of polymeric thermoplastic materials with liquid crystals have shown that they can be used with good results for the injection molding of the coating film layers or of the ultrathin coatings of relatively small size, for example with diameters. up to about 30 cm. This material itself forms a structure with crystals oriented in the direction of injection, offering a preferential orientation for a better propagation of acute energy, from 150 at the point of action to the edges of the panel.

In addition, such a technique for forming thermoplastics of the aforementioned or other type allows the assembly of forming machines to transport positioning and centering pieces, such as, for example, grooves or rings for precise placement of the component parts of the transducer, such as the motor coil assembly and the magnetic suspension. Moreover, for some types of materials, less resistant, used when making the core, it is considered that it would be advantageous to increase locally, up to 150% of the diameter of the translator, the thickness of the covering film state, for example on a portion or on circular surface, in order to increase the resistance of the respective portion or surfaces and to advantageously couple the vibrational energy in the panel. In this way, by using softer sponge materials, the high frequency response is improved.

The materials used to make the core used as a core are honeycomb shaped or have a corrugated appearance, being made from sheets or sheets made from aluminum alloys or Kevlar ®, Nomex ®, ordinary or pressed paper, and from different types of layers. films made of synthetic plastics, such as expanded or spongy plastics, or even paste materials, including metal aerogels, if they are of sufficiently low density. Some of the materials suitable for making the core used as a core have practically the property of automatically forming their coating film states at the time of manufacture and / or may have an inherent rigidity sufficient to be used between the coating film layers without require rolling. A further 170 material, which can be used in making the layer used as a core and having the trade name 'Rohacell', is known for its high performance, being of the type without a covering film layer, the material can be used as a radiant panel. Basically, the aim is to obtain a material of low weight and overall rigidity corresponding to a particular application, assuming including optimization especially of the layers used as core, of the covering film layers and of the portions between them.

Some of the preferred embodiments of such a panel use metal sheets or sheets of metal alloys, or as an alternative, use a carbon fiber reinforcement. Both of the above solutions, as well as other metal honeycomb structures or 180 aerogels (Kevlar and carbon alloys), used as a core, have special radio frequency shielding properties, which is an element of particular importance in different EMC applications. Conical type speakers or conventional panels do not have such inherent EMC shielding properties.

In addition, it should be noted that in the preferred embodiments 185 of the invention, piezoelectric and electrodynamic transducers have electromagnetic radiation or magnetic fields of dispersion, of negligible intensities. Conventional loudspeakers have large magnetic fields, which can be up to one meter apart, unless specific countermeasures are taken.

In the case of applications where good shielding is required, the electrical connections 190 can be made to the electrically conductive parts of a corresponding type DML panel or to an electrically conductive foam, or it can be used an interface, similar to those used in mounting. edges.

RO 119045 Β1

The elastic suspension means 3 provide the damping of the edges of the panel 2 to prevent excessive displacement of the edges of the respective panel. In addition or as a displacement variant, it can also be used as a damping, applying, for example, patches fixed to the panel in certain preselected positions to attenuate excessive movements, in order to ensure the uniform distribution of the resonance throughout. panel. Such patches can be made of material made of bitumen, usually used in the enclosures of conventional speakers, or they can be made of a polymeric, laminated, elastic or rigid material. Some materials, especially paper and cardboard, as well as some materials used as a core, may exhibit self-attenuation properties. When desired, the cushioning can be increased when making the panel, by using adhesives whose hardening is elastic, instead of using some rigid hardening.

A selective and efficient cushioning implies a specific application on the panel and also on the laminated material which is an integral, permanent part thereof. The edges and corners may prove particularly important for low frequency vibration modes of the panels, which are dominant and of lower dispersion. Fixing the edges, for a cushioning element, can usefully lead to obtaining a panel whose material, in laminated form, is completely trapped on the edges, even though its corners will remain relatively free, for example to allow for possible extension of operation at relatively low frequencies. The fixing can be done with the help of adhesive or even self-adhesive materials. Other useful forms of depreciation, especially when pursuing certain special effects and / or medium and high frequencies, may be in the form of one or more appropriate weights, fixed by the laminated material in certain predetermined positions, practically located medially within the respective area.

An acoustic panel of the type described above is bidirectional. The energy of the sound coming from the rear speaker is not very correlated with that of the sound coming from the front speaker. consequently, the advantage of a global summation of the acoustic power in the room is obtained, a uniformly distributed sound energy in terms of frequencies, reduced stationary wave effects and with the advantage of better reproduction, in the reproduction of sound, space and environment. naturally registered.

If the radiation emitted by an acoustic panel is largely non-directional, it must be taken into account, however, that the percentage correlation of the acoustic information increases outside the axis. For a better focus on artificially created stereo images, the layout of the speakers, as well as the images, at the height of a person standing has the advantage of an easy off-axis position for listeners who are usually seated, which leads to optimization of the stereo effect. In the same way, the left / right triangular geometry that includes the listener provides an additional angular component. In this way, a good stereo effect can be obtained.

For a group of listeners there is an advantage, compared to playing using a conventional speaker. By the nature of dispersion that intrinsically characterizes the sound emission made by the acoustic panel, a volume of sound is produced that does not satisfy the dependence law inversely proportional to the square of the distance, for an equivalent point source. Due to the fact that the intensity reduction with the distance is much smaller than the one determined by applying the dependence law inversely proportional to the square of the distance, it will result that for the non-centrally located listeners, who occupy disadvantaged places, the intensity of the field for the panel type speaker will produce a stereophonic effect. superior to that of conventional speakers. This is due to the fact that the non-centrally located listener is no longer subject to double shortcomings due to the proximity to the speaker in the immediate vicinity: firstly, the excessive increase in the volume of the speaker located nearby and secondly, the corresponding reduction of the volume for the farther speaker.

RO 119045 Β1

There is also the advantage of a flat panel, low weight, nice looking, good looking sound quality speaker, requiring only a translator, without producing sound translations for a whole range of sounds from each diaphragm of the panel.

FIG. 3 shows a diffuser 81, in the form of a panel generally similar to that represented in FIGS. 1 and 2, and wherein a radiant element 2, in the form of a panel, operating in a distributed manner, is formed having an opening 82 having a generally rectangular shape on the surface, in which is mounted a second radiant element 4, acoustic, panel-shaped, distributed in operation, having elastic suspension means 3 interposed between said radiant elements 2 and 4, panel-shaped. The second radiant element 4, in the form of a panel, is constructed in the same way as the first radiant element 2 in the form of a panel, for example with a central core 22 which separates some film layers 21. The radiant element 4, shaped panel, is operated by its own transducer 9, wholly and exclusively mounted on, or within the radiant element 4, panel-shaped, in a predetermined location to produce a high-frequency output acoustic signal, while the radiant element 2, in the form of a panel, is actuated by a separate transducer 9 to produce a lower frequency acoustic signal so that the speaker 81 can easily encompass the entire acoustic spectrum. Such a configuration may be useful if losses in panel material tend to attenuate high frequencies. In addition, more than one transducer can be mounted on, or in each of the panels to improve their performance.

FIG. 4 shows how a radiant element 2, in the form of a panel, operating in a distributed manner according to the invention, and for example of the type shown in FIGS. 1 and 2, can be excited to be resonated. by some transducers 70 and 71, pair, of the type of transducer 9. The smallest of the transducers 70, 71 is a piezoelectric transducer 70, of high frequency, for example of the type presented in Fig. 7, and the largest of these is an electrodynamic transducer 71, for example, of the type presented in the publications of the PCT patent applications W097 / 09859, WO97 / 09861, W097 / 09858.

The transducers 70, 71 are excited by an amplifier 10 coupled in parallel with the respective transducers 70.71, by means of a voltage-transformer 72 and an adaptive resistor 73, mounted in series with the piezoelectric transducer 70, taking into account the requirements its relatively high voltage. If necessary, more than one translator 70 and / or one translator 71 may be used to increase efficiency.

in FIG. 5 shows how a radiant element 2 in the form of a panel operating in a distributed manner according to the present invention, for example of the type shown in FIGS. 1 and 2, can be excited by some transducers 70, 74, pair, of the type of the transducer 9, the transducer 70 being a high frequency piezoelectric transducer, for example of the type shown in fig. 7, and the translator 74 being a piezoelectric transducer of the type presented in the publication of PCT patent application W097 / 09861. The element 75 indicates that the transducer 74 is loaded with a weight to increase its inertia. The transducers 70, 74 are excited by an amplifier 10, with which they are connected in parallel, with some resistors 78, interposed to produce a frequency divider network. If necessary, more than one translator 70 and / or one translator 74 may be used to increase efficiency.

in FIG. 6 shows how a radiant element 2 in the form of a panel operating in a distributed manner according to the present invention, for example of the type illustrated in Figs. 1 and 2, can be operated by a pair 68,69 of electrodynamic transducers, for example, the type presented in the publications of PCT patent applications WO97 / 09859,

WO97 / 09861, WO97 / 09858.

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RO 119045 Β1

The transducer 68 behaves as a high-frequency exciter, thus being characterized by a low inductance, while the translator 69 behaves as a low-frequency exciter, being characterized by a high inductance.

The transducers 68.69 are excited in parallel by an amplifier 10 with a capacitor 77, in series with the transducer 68 to act as a frequency divider to transmit most of the high frequency signals to the transducer 68. If necessary, more than one translator 68 and / or one translator 69 may be used to increase efficiency.

in FIG. 7 shows a transducer 9 for a panel with distributed mode of work, in the form of discs 27 pair, of piezoelectric crystals type, mounted on a disc 118, for example of brass, which is fixed on one of the faces of the radiant element 2 in the form of the panel, for example, by means of adhesive coupling means 20. during operation, an acoustic signal, applied through the conductors 28 of the transducer 9, can cause the flexion of the piezoelectric disc 27, thus causing an elastic, local deformation of the radiant element 2 in the form of a panel, which produces bending waves in the panel.

Claims (11)

claims 1. Panel-shaped diffuser characterized in that said panel-shaped diffuser (81) comprises a first radiant element (2), consisting of a light and rigid panel having the ability to maintain and propagate, through flexural waves. , vibrational input energy, in at least one active area that extends transversely on the thickness, to have vibrational components of resonant type distributed over the respective area, and to have preferential locations or locations, predetermined, within that zone, for arrangement , in two of the respective locations or locations, of first and second transducers (9), mounted on said radiant element (2), to determine the vibration of said radiant element (2), so that it enters the resonance, forming thus an acoustic transmitter that generates acoustic radiation when it resonates. 2. Speaker according to claim 1, characterized in that the first and second transducers (9) are adapted for operation in a different frequency range. 3. Speaker according to claim 1 or 2, characterized in that the radiating element (2) has a cell core (22) interspersed between layers (21). 4. Speaker according to claim 3, characterized in that it comprises a frame (1) that supports the radiant element (2), as well as some elastic suspension means (3) by means of which the radiant element (2) is fixed by the frame (1) . 5. Speaker according to claim 4, characterized in that said frame (1) surrounds the radiant element (2), and the elastic suspension means (3) are fixed by the edge of the radiant element (2). 6. Speaker according to any one of the preceding claims, characterized in that the first and second transducers (9) are integrally and exclusively mounted on the radiant element (2). 7. Speaker according to any one of the preceding claims, characterized in that one of the transducers (9) is electromagnetic. 8. Speaker according to claim 7, characterized in that one of the transducers (9) is piezoelectric. 9. Speaker according to any one of the preceding claims, characterized in that it comprises a second radiating element (4), having the capacity to maintain and propagate, through flexural waves, input vibrational energy, in at least one active area which is RO 119045 Β1 340 extends transversely on thickness, to have vibrating components of resonant type distributed over the respective area, and to have preferential locations or locations, predetermined, within that zone, for the arrangement, in one of the respective sites or locations, of a translator ( 9) mounted on said radiant element (4), to determine the vibration of said radiant element (4), so that it resonates, thus forming an acoustic emitter which generates an acoustic radiation when it resonates, the second radiant element (4) being mounted on, or within, the first radiating element (2), said elastic suspension means (3) coupling the radiating elements (2 and 4), first and second. 10. Speaker according to claim 9, characterized in that the second radiant element (4) is mounted in an opening (82) practiced in the second radiant element (2). 11. Speaker according to claim 10, characterized in that the second transducer (9) is integrally and exclusively mounted on the second radiating element (4).