RO119048B1 - Loudspeaker - Google Patents

Abstract

A loudspeaker (81) comprising an enclosure, an acoustic radiator (2) in the enclosure, a compliant suspension (3) mounting the radiator in the enclosure for pistonic movement relative thereto, and transducer means (9) for driving the radiator pistonically, characterized in that the radiator is a panel-form distributed mode acoustic radiator, by a first transducer mounted wholly and exclusively on the radiator to vibrate the radiator to cause it to resonate, and by means (11) for varying the air pressure in the enclosure to cause the radiator to move pistonically.

Description

The present invention relates to a loudspeaker of the type which are 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 a 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, independent of direction, a coefficient of resistance to bending (B) equal to the mass of the panel at power 3, per unit area (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 US Pat. No. 3164221, a RICH Applicant discloses a low-frequency loudspeaker, which comprises a housing, an encoder in the housing, a suitable suspension that mounts the transmitter to the housing, to execute a movement like a piston, and actuating elements such as a piston, to vary the air pressure in the housing, to cause the emitter to move like a piston.

US-A-3247925, Warnaka holder, 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 the opening of the national phase of this patent application. Such elements have the capacity to maintain and propagate, through flexural waves, input vibration energy, in the operational area or areas 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 rigidity 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, in order to dispose of a translator in the respective zone or areas, in particular in that part or operationally active or mobile parts thereof, effective in terms of acoustic vibration activity and in terms of signals, usually electrical, corresponding 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 ¹ without a translator, such as, for example, for reverb, for acoustic filtering or for the realization. an acoustic harmony in a space or a room, and in active acoustic devices "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, in order to be converted respectively to beep, or such as, for example, microphones, when exposed to a beep to be converted to another signal.

This invention relates especially to acoustic devices in the form of loudspeakers.

RO 119048 Β1

Elements of the above are known, such as, for example, the 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 characteristics of the invention. The specific embodiments of the invention herein.

The object of the invention is a diffuser comprising a housing, an acoustic emitter (radiator) in the housing, an active suspension mounting the transmitter in the housing, to execute a movement like a piston relative thereto, and elements for varying the air pressure in the housing. , in order to cause the transmitter to move like a piston, characterized in that 55 is an element which has the capacity to maintain and propagate, by means of flexural waves, vibrational input energy, in at least one active area that 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 area, for the arrangement in one of those places or locations, of a fully and exclusively mounted translator 60 , on said radiant element, to determine the vibration of said radiant element, such that it enters the resonance, thus forming an acoustic emitter that generates acoustic radiation when it resonates. The air pressure variation elements comprise an air pump. The air pump may comprise a secondary housing, an actuator such as a piston mounted in the secondary housing, and elements 65 engaging the interiors of the respective enclosures so that the air pressure waves produced by the movement of the actuating member as a piston are transmitted to the respective housing. Sound-absorbing elements may be provided in said housing and / or in the secondary housing. The emitter (radiator) may comprise a centrally layered cell (core) portion of a pair of light coatings (layers) in upper modules. 70

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;

- has special properties for shielding radio frequencies and reducing the effects of stationary 75 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 in the publication of PCT patent application WO97 / 09842; 80

- 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 with a distributed operation, of the type of the one in fig. 2a, presented in two embodiments; 85

- Fig. 3, the schematic diagram of a loudspeaker allowing a distributed operation, according to the embodiment of the invention.

Figure 1 shows a panel-shaped speaker 81, of the type described in PCT patent application publication WO97 / 09842, the applicant of which is the same as the PCT patent application that was the basis for opening the national phase of the present Patent applications, diffuser 90, 81 having a frame 1, rectangular, of which elastic suspension means 3 are fixed, arranged around its internal peripheral contour, supporting a radiant element 2, acoustically, in the form of a panel. , of distributed type (with distributed operation). A translator 9, for example of the type widely presented in PCT patent application publications WO97 / 09859, WO97 / 09861, WO97 / 09859 having the same date and 95

RO 119048 Β1 Applicant with the PCT 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 with those presented in the publication of the PCT patent application W097 / 09842, mentioned above, in order to produce, in the panel, a bending wave that would cause its resonance to occur, in order to generate 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.

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 a cell matrix 98 having a honeycomb structure made of metal foil, plastic or other similar material, and whose cells are arranged transversely, relative to the plane of the panel, being closed by two opposing film layers 21 , made, 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.

Proposed materials 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 fiber-reinforced plastics, etc., and sheets 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

R0119048 Β1 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 150 foam 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 155 foam 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. Another 160 material that can be used in making the layer used as 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 suitable for 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 170 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 kept in mind that in the preferred embodiments 175 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, electrical connections can be made to the electrically conductive parts of a corresponding type DML panel or to an electrically conductive foam, or an interface similar to those used can be used. when mounting the edges.

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, for example, applying panels fixed to the panel in certain preselected positions to mitigate excessive movements in order to ensure uniform distribution of the resonance throughout. panel. Such patches can be made from material made of bitumen, usually used in conventional speaker enclosures, or they can be made of a polymeric, laminated, 190 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.

RO 119048 Β1

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 offers an additional angular component, so a good stereo effect can be achieved.

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 another variant of the combined embodiment of the invention, which exemplifies the way in which the acoustic transmitter 2 behaves within the speaker 81, namely following a piston type movement, and also having a distributed operation. The figure shows an acoustic transmitter 2 operating in a distributed manner, which is of the type shown in Figs. 1 and 2, respectively, in the form of a rigid, light weight panel, forming a front wall of an enclosure 8 similar to a boxes, which has some side walls

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245

135 and a rear wall 12, for example a plate of medium density fibers, defining together a cavity 155. A panel 51 of an acoustic absorption material is provided in cavity 155, to damp the standing waves. The acoustic transmitter 2, in the form of a panel, is mounted in the enclosure 8, with the aid of elastic suspension means 7, for example for simulating a border surrounding a speaker 81 of a conventional conical type, in the form of a piston, and for moving a translator 9 of the type described in the publications of PCT patent applications WO97 / 09859, WO97 / 09861, WO97 / 09859 having the same date and the same applicant as for the PCT patent application which was the basis for the opening of the national phase of the present patent application. In order to propagate the bending waves in the panel, the transducer 9 is integrally and exclusively mounted on the radiant element, which constitutes the acoustic transmitter 2 in the form of a panel, at a certain predetermined location, as described in the publication of PCT patent application WO97 / 09842 having same date and same applicant with the PCT patent application which was the basis for opening the national phase of this patent application.

The cavity 155 inside the enclosure 8 is coupled to a pump 11 for generating the serious frequencies (basses), which is located inside an enclosure 185 in the shape of a box, which contains an actuating unit 42 for controlling the serious frequency speaker, in the form of a piston. , by means of a tube 90, in the form of a tube, through which the pressure waves of the acoustic frequency air in the field of serious frequencies are applied to the cavity 155 inside the enclosure 8, to determine the displacement, by a piston-type movement, of the acoustic transmitter 2 in the form of a panel, on the elastic suspension means 7, to produce a low-frequency acoustic output signal. At the same time, through the transducer 9, the acoustic transmitter 2 in the form of a panel is determined to enter the resonance, resulting in its emission of a high frequency acoustic output signal. An amplifier 10 is provided to supply an acoustic output of the serious frequency generating pump 11 and the transducer 9, to support the operation of the speaker 81.

Claims (5)

claims 1. Speaker comprising an enclosure (8) in which, with the aid of elastic suspension means (7), an acoustic transmitter (2) is mounted so that it can perform, in relation to the enclosure (8), a similar movement with that of a piston, said diffuser (81) further comprising means for varying the pressure (11) to vary the pressure of the air in the chamber (8) so that the acoustic transmitter (2) can perform a movement of movement similar to that of a of a piston, characterized in that the acoustic transmitter (2) is a radiant element having the capacity to maintain and propagate, by means of flexural waves, vibrational energy of input, in at least one active area that extends transversely on the thickness, in order to have vibrating components of resonant type distributed over the respective area, and to have preferential locations or locations, predetermined, within that area, for arrangement, in one of the respective locations or locations of a transducer (9) integrally and exclusively mounted on said radiant element, to determine the vibration of said radiant element (2), so that it enters the resonance, thus forming an acoustic transmitter (2) that generates a acoustic radiation when it resonates. A diffuser according to claim 1, characterized in that the pressure variation means (11) comprises an air pump. 3. Speaker according to claim 2, characterized in that the air pump comprises an auxiliary enclosure (185), an exciter (42) with a piston-type displacement movement, mounted within the auxiliary enclosure (185), and coupling means (90). ) that connect the interiors 250 255 260 265 270 275 280 285 290 EN 119048 Β1 of the respective enclosures (8,185), so that the air pressure waves that are produced by the movement of the exciter (42) with a piston-type displacement movement are transmitted to said first enclosure (8). 4. Speaker according to claim 3, characterized in that it comprises sound absorbing means (51) in the first enclosure (8) and / or in the auxiliary enclosure (185). 5. Speaker according to any one of the preceding claims, characterized in that the acoustic transmitter (2) comprises a cell core (22), lightly intercalated between pair, light and high modularization layers (21).