RO119047B1 - Panel-shaped speaker - Google Patents

Abstract

A panel-form loudspeaker having a distributed mode acoustic radiator (2) and a transducer (9) coupled to vibrate the radiator to cause it to resonate, characterised by a second transducer (63) coupled to the radiator to produce a signal in response to resonance of the radiator due to incident acoustic energy.

Description

The present 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.

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 in sound signal, or as are, for example, microphones, when they are exposed to a sound signal to be converted to another signal.

The present invention relates in particular to active acoustic devices, in the form of speakers. 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 invention relates to a panel diffuser having an element capable of maintaining and propagating, by means of flexural waves, vibratory input energy, in at least one active zone that extends transversely on thickness, to have vibrational components of resonant type, distributed over the respective area, and to have preferential locations or locations, predetermined, within that area, for arranging in one of those locations or locations, a translator mounted integrally and exclusively, on said radiant element, to determine the vibration of said element radiant so that it enters

EN 119047 Β1 in resonance, thus forming an acoustic emitter which generates acoustic radiation 50 when it resonates and wherein the speaker is also a microphone and comprises a secondary transducer mounted on the element in one of said locations or sites to produces an audible signal in response to the resonance of the element due to incident acoustic energy. The element can be mounted in a surrounding frame by means of an interposed elastic suspension. The element may contain a rigid, lightweight panel having a cellular core 55 layered between the shells.

The elastic suspension can be attached to the edge of the panel. The first translator and the secondary translator can be fully and exclusively mounted on the transmitter. At least two of the secondary translators mentioned are located in the locations or sites mentioned on the transmitter. Another transducer may be provided on the transmitter in a predetermined location or 60 sites, to produce a signal in response to the transmitter's resonance due to the incident acoustic energy, and means for comparing the signal generated by said translator with those generated by the translator may be provided. or said secondary translators. The means of comparison may comprise means for receiving and conditioning signals, as well as means for producing the signal. 65

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 and a higher stereo effect, compared to that of conventional speakers;

- It has special properties for shielding radio frequencies and reducing the effects of 70 stationary waves.

The following is an example of an embodiment of the invention, in connection with FIGS.

- Fig. 1, constructive diagram of a distributed type diffuser, according to the description of the invention from 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, a cross-sectional view, on an enlarged scale, of a radiant element with a distributed operation, of the type shown in Fig. 2a, presented in two embodiments;

- fig. 3, the constructive diagram of a speaker equipped with the function of microphone, and allowing a distributed operation, according to the embodiment of the invention;

- Fig. 4, perspective view of a piezoelectric transducer.

Figure 1 shows a panel 81 speaker, of the type described in PCT patent application publication WO97 / 09842, the applicant of which is the same as the 85 PCT patent application which was the basis for the opening of the national phase of of the present patent application, the diffuser 81 having a rectangular frame 1, of which some means of elastic suspension 3 are fixed, disposed around its internal peripheral contour, which support a radiant element 2, acoustic, in the form of a panel, distributed type (with distributed operation). A translator 9, for example of the type that is widely presented in the publications of 90 PCT patent applications WO97 / 09859, WO97 / 09861, WO97 / 09859 having the same date and the same applicant as the PCT patent application, is fully 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 PCT patent application W097 / 09842, mentioned above, in the purpose of producing, in the new frame, 95 bending waves that cause its resonance entry, in order to generate an acoustic output emission.

RO 119047 Β1

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 film layers of the panel are metallic, they can be made astrally so that they act as a heat radiator of the transducer, to evacuate the heat from the coil of the translator-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 the realization of the frame 1 we mention the light frame type structures. painting 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.

Figure 2b shows, on a larger scale, the radiant element 2 in the form of a light, rigid panel, comprising a core 22, made of a rigid foam 97, made of plastic, such as, for example, polyvinyl chloride cross-linked, or 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 layers of film 21 opposite, made, for example, of paper, cardboard, plastic or sheet or sheet metal. When the film layers 21 are plastic, for growth of its (Young's) module, they may be fiber reinforced, in a manner known per se, the fibers being, for example, carbon, glass, Kevlar® or the like.

Proposed materials for achieving 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 films. High modulus (Young) synthetic plastics, such as Mylar®, Kaptan®, polycarbonate, phenol, polyester or associated plastics, and fiber-reinforced plastics, etc., and foils and sheets. 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 coated film layers or of the ultra-thin 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 better propagation of acute energy, from 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 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.

RO 119047 Β1

The materials used to make the core used as a core are honeycomb shaped or have a wavy appearance, being made from sheets or sheets made from aluminum alloys or Kevlar®, Nomex®, plain or pressed paper, as well as different types 150. film layers 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 155 to be used between the coating film layers, without require rolling. Another material that can be used to make the core 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 particular application, assuming including the 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 165. Both of the above solutions, as well as other metal or aerogel honeycomb structures (Kevlar and carbon alloy), 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. 170 In addition, it should be taken into account that in the preferred embodiments 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. 175 for applications where good shielding is required, electrical connections may be made to the electrically conductive parts of a corresponding type DML panel or to an electrically conductive foam, or an interface may be used, similar to those used in mounting. edges.

The elastic suspension means 3 ensure the damping of the edges of the panel 2 for 180 to prevent excessive movement of the edges of the respective panel. In addition or as a displacement variant, it can also be used as a damping, for example applying patches fixed to the panel in certain preselected positions to mitigate excessive movements in order to ensure uniform distribution of the resonance throughout the panel. .

Such patches can be made of material made from bitumen, usually used in 185 enclosures of conventional speakers, or 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, when making the panel, the damping can be increased by using adhesives whose hardening is elastic, instead of using some rigid hardening. 190

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 an element of cushioning, can usefully lead to obtaining a panel whose material, in laminated form, is completely stuck on the edges, even if its corners will

EN 119047 Β1 remains relatively free, for example to allow a 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 that determined by applying the dependence law inversely proportional to the distance square, it will result that for the non-centrally located listeners, who occupy disadvantaged places, the field intensity for the panel type speaker will produce a higher stereo effect. , compared 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 of 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 speaker further away. .

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.

Figure 3 shows a radiant element 2, made according to the present invention, in the form of a panel, and operating in a distributed manner, being of the type described in Figs. 1 and 2, characterized by both speaker and microphone functions, for example , for use in an interactive environment. Although not shown in Fig. 3, the way in which the radiant element 2 is mounted in the form of a panel, it is mounted in a frame 1 from which some elastic suspension means 3 are fixed, according to the representation in fig. 1 and 2. The frame 1 is suspended by a pair of cables 33, for example, from the ceiling or it may be a frame that allows to be placed on the ground (not shown).

The radiant element 2 in the form of a panel is excited, being determined to resonate so as to produce an acoustic signal through a transducer 9 of the type described in the publications of PCT patent applications WO97 / 09859, WO97 / 09861,

R0119047 Β1

WO97 / 09859, whose applicant is the same as the one of the PCT patent application, which was at 245 the opening of the national phase of the present patent application, the transducer 9 being connected and excited, on the return path, with an amplifier 10.

The radiant element 2 in the form of a panel is also provided with a pair of vibration transducers 63 which can be piezoelectric transducers of the type shown in Fig. 4, which are coupled in parallel to activate reception and conditioning means 250 signals 65, which connect to some means of output signals 66. A vibration transducer 63, additionally, of the type shown in fig.4, disposed within the radiant element 2 in the form of a panel, is coupled to activate a filter / correlator 64 from the output of which the signal reception and conditioning means 65 are supplied to carry out a correction of the signal. 255 in FIG. 4 shows a transducer 9 for use in a radiant element 2 in the form of a panel with distributed operation, the transducer 9 being made in the form of a piezoelectric exciter 27 of crystalline disc type, which is mounted on a brass disk 118 , which is attached to a face of the radiant element 2 in the form of a panel, by means of adhesive connection means 20. During operation, the applied acoustic signal, 260 by means of conductors 28, to the transducer 9, produces the bending of the piezoelectric exciter 27, crystalline disk type, thus producing a local, elastic deformation of the radiant element 2 in the form of a panel, which causes the propagation in the panel of the bending waves.

The invention allows to make a simple acoustic device, characterized by both functions of speaker and microphone, which can be used, for example, in interactive applications 265.

Claims (8)

claims 1. Panel-shaped diffuser, characterized in that it comprises a radiant element 270 (2) having the capacity to maintain and propagate, through flexural waves, vibrational input energy, in at least one active area that extends transversely on the thickness, to have vibrating components of resonant type distributed on the respective area, and to have preferential locations or locations, predetermined, within that area, for the arrangement, in one of the respective locations or locations, of a transducer (9) mounted on 275 said radiant element (2), in order to determine the vibration of said radiant element (2), so that it enters the resonance, thus forming an acoustic transmitter which generates an acoustic radiation when it resonates, the speaker further comprising a microphone. and a second transducer (63), mounted on the radiant element (2) in one of the respective sites or locations, for the product the request for an output signal, in response to 280 resonance of the radiant element (2) due to the incident acoustic energy. Speaker according to claim 1, characterized in that the radiant element (2) is mounted in a frame (1) surrounding it, by means of elastic suspension means (3), interposed. 3. Speaker according to claim 1 or 2, characterized in that the radiant element 285 (2) consists of a light and rigid panel having a cell core (22) sandwiched between layers (21). 4. Speaker according to claim 3, characterized in that the elastic suspension means (3) are fixed by the edge of the panel that makes up the radiant element (2). 5. Speaker according to any one of the preceding claims, characterized in that 290 the first and second transducers (9.63) are integrally and exclusively mounted on the radiant element (2). RO 119047 Β1 6. Speaker according to any one of the preceding claims, characterized in that it comprises at least two transducers (63) seconds, disposed on the radiant element (2), in one of said predetermined locations or preferential locations. 295 7. The speaker according to claim 6, characterized in that it comprises an additional transducer (63), disposed on the radiant element (2), in one of said locations or preferential locations, for producing a signal, in response to the resonance of the radiant element (2). ) which is due to the incident acoustic energy, the speaker also comprising comparative means (64.65) for comparing the signal that is produced by the additional translator (63) 300, with those produced by the translator or translators (63) seconds. 8. Speaker according to claim 7, characterized in that the comparator means (64,65) comprise signal reception and conditioning means (65), the output signal of which is provided to signal output means (66).