RU2744774C1 - Recessed flat loudspeaker - Google Patents

Abstract

FIELD: acoustics.

SUBSTANCE: invention relates to acoustics, in particular to flat loudspeakers. The built-in flat loudspeaker includes a housing, a flat membrane and a transverse acoustic wave acoustic vibration drive. The housing is made in the form of a flat support frame, and a sound-emitting flat rectangular membrane is fixed on the frame, the membrane is made in the form of a honeycomb filler, a surface layer glued to the honeycomb structure on both sides and a stabilizing impregnating composition based on polyurethane primers and varnishes covering the surface layers, reverse the side of the diaphragm is covered with a damping layer. The drive of acoustic vibrations is made in the form of at least one exciter of acoustic vibrations, including ferrite parts of the magnetic circuit. The acoustic vibration exciter is fixed on a flat support frame by means of a bridge and is attached at one end to a flat membrane within a line passing along the plane of a rectangular membrane and coming out of any vertex of a rectangular membrane, and ending at a point on the opposite vertex of the horizontal side of the membrane located at a distance of 2 / 3 of the opposite side of the membrane from the top horizontally.

EFFECT: technical result is to improve the quality of sound reproduction, reduce the installation depth for mounting the loudspeaker and simplify the installation.

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Description

The proposed loudspeaker is intended primarily for installation acoustic solutions, as the final link-emitter of acoustic waves.

This loudspeaker is a flat, square, or rectangular panel for installation in the existing infrastructure of Armstrong type suspended ceilings, or for ceiling or wall flush mounting in building structures such as: plasterboard, wood and other frame-panel structures, as well as tension ceilings. Installation of such flat loudspeakers in the form of freely suspended on cables in a horizontal, inclined or vertical position is possible.

The built-in flat loudspeaker is applicable in acoustics. In the following areas:

* Meeting rooms and conference rooms,

* Alert lines,

* Cafes, bars, restaurants,

* Shopping and entertainment centers, shops, pavilions,

* Offices,

* Museums, exhibitions, galleries,

* Railway stations, airports,

* Hotels, theaters, cultural centers,

* Schools,

* Industrial premises,

* Shipbuilding (notification in aisles, engine rooms, cabins, cabins)

A variety of built-in loudspeakers are known in the art. For example, a large assortment of such products is offered by Roxton ( http://www.roxton.pro/cat/gromkogovoriteli/potolochnie_gromkogovoriteli.html ). These loudspeakers are, in fact, ordinary cone speakers built into a compact body. Due to the design features of the speaker, the overall installation depth of such a built-in loudspeaker is rarely less than 100 mm, which makes it difficult to install such products in a structure with a small installation depth. (The height of a standard plasterboard frame profile is 54 mm). Since the housing of a built-in loudspeaker cannot be large enough for design reasons, this significantly increases the lower boundary limit of the frequency in its operation. In practice, this is usually 80-100 Hz. In addition, the cone speaker of a conventional loudspeaker gives a sound beam angle of about 90 °, in contrast to our flat loudspeaker, which has a circular (360 °) directivity pattern (in the case of a free-hanging installation). The cumulative disadvantages of conventional built-in loudspeakers limit their scope and preclude their use in environments with high demands on sound quality. No worthy alternative is offered.

Also known flat recessed speakers "under the plaster". For example, Ceratec Cerasonar 3060 X1 is the closest to ours. ( Https://stereo.ru/to/b43g6-vstraivaemaya-akustika-ceratec-cerasonar-i-steny-zapoyut ) The column has the following main characteristics: depth 50 mm, width 300 mm , length 600 mm., frequency range 90-18000 Hz.

This loudspeaker is a membrane with a layer of foam rubber of a special serrated shape glued on the back side, fixed to the membrane by an exciter of acoustic vibrations and terminals for connecting to the amplifier. Also included is a special mounting frame for fixing the loudspeaker in the wall hole. After installation, the membrane needs to be plastered or putty and decor applied. cover or wallpaper. This mounting feature strongly and unpredictably makes the membrane heavier, impairing its acoustic properties. Mounting hidden under the trim makes it impossible to access the loudspeaker elements for maintenance or in the event of a breakdown. As a result, the consumer is offered a loudspeaker with a limited (90Hz) lower frequency range and far from ideal sounding, implying large expenditures on installation activities in relation to the initial stage of finishing and construction work.

Known patent US 6,332,029 Bl Henry Azim, in which figure 25 and 26 shows the possibility of embedding a sound-emitting membrane operating on the principle of the formation of resonant bending modes directly into the ceiling structures. The disadvantages of the proposed solution can be considered: non-optimal shape of the membrane in the form of a square, which differs from the aspect ratios 3/7, 4/9, 5/13 recommended in the same patent. In the opinion of the author himself, the square cannot provide the necessary optimal distribution of the resonant modes with the inevitable deterioration of the sound parameters. The absence of a body with a significant mass, which is used in this technology as a fulcrum for the process of reflection of the flexural wave from the edge of the membrane, along with the absence in the figure of means for holding the body of the exciter, leads to a strong decrease in the efficiency of such a loudspeaker and an increase in the total distortion of the acoustic signal. This will prevent these speakers from being used in environments with increased demands on sound quality while meeting the growing demands for energy efficiency systems.

The closest technical solution can be considered the patent JP2010199818A, which proposes a loudspeaker of the "flat speaker" type used on the ceiling or wall of a dwelling or office.

A loudspeaker with a flat diaphragm is proposed, driven by a drive device fixed in the geometric center of the diaphragm. Includes: frame, flat diaphragm (made of wood, metal polymer, transparent resin, or honeycomb structure not described in detail) fixed to one side of the frame, drive unit fixed to the frame, back plate, hard rubber spacers.

The fundamental disadvantages of such a flat loudspeaker include the following:

In the construction described above, the membrane is square. This results in an incorrect distribution of resonant modulations, greatly reducing the acoustic qualities of the loudspeaker.

The emitting membrane is proposed to be made either from a composite - metal + polymer, or from wood, or from a transparent resin, which gives an increased mass of the membrane and the impossibility of realizing high-quality sound parameters at low frequencies, as well as an unnatural timbre color.

To compensate for the design shortcomings related to the non-optimal distribution of resonances over the area of the membrane, inside the case between the radiating membrane and the top cover, special couplings-spacers made of hard rubber are used, which significantly complicate the design and reduce the efficiency of the loudspeaker. In addition, the author proposes to improve the amplitude-frequency response by complex manipulation of the adjustment of the position of the delivery couplers and their number, which again leads to the difficulty of repeatability of a successful result on an industrial scale of mass production.

The Japanese patent uses a solid top cover to isolate the backside of the radiation and essentially transforms the structure into a kind of acoustic design called a "closed box". Such a solution does not allow realizing high quality characteristics of the sound signal, in particular, due to re-reflections arising from the upper (back with respect to the radiating membrane) cover and returning to the membrane with a phase shift. As a result, the loudspeaker emits a "dirty sound" and suddenly loses its efficiency in the low frequency range.

The drive for excitation of acoustic vibrations of the membrane is attached at its geometric center. In practice, this means a deterioration in the acoustic properties of a loudspeaker due to the suboptimal distribution of resonant excitation zones, with an inevitable increase in harmonic distortions of up to tens of percent and a distorted amplitude-frequency characteristic in reality, with a spread of up to 30 dB.

The loudspeaker has a housing that is tightly connected to the membrane and has an internal air volume of the order of several liters.This solution completely deprives of all the advantages of flat loudspeaker technology: the practical limit of the lower audio frequency is 100 Hz, the impossibility of realizing such high-quality sound parameters as intelligibility and micro dynamics of sound, etc. etc. Such a loudspeaker is inapplicable in conditions of increased requirements for sound quality.

The installation depth of the Japanese speaker is as much as 110 mm (judging by the picture provided). This does not offer any advantages over conventional recessed loudspeakers where installations with a shallow installation depth are required.

The technical solution we offer allows us to solve the following tasks:

1) Expansion of the lower cutoff frequency of the loudspeaker,

2) Obtaining high-quality sound indicators using minimal material consumption,

3) Reduced installation depth for indoor loudspeaker installation,

4) Improving the uniformity of the sound field in the coverage area of the operating loudspeaker,

5) Maximum ease of installation and reduction of installation costs in the existing architecture of buildings.

The technical result is to improve the quality of sound reproduction, reduce the installation depth for mounting the loudspeaker and simplify the installation.

The technical result is achieved by the fact that: a built-in flat loudspeaker includes: a housing, a flat membrane and a drive for acoustic vibrations of a transverse acoustic wave.

In this case, the body is made in the form of a flat support frame, and a sound-emitting flat rectangular membrane is fixed on the frame,

the membrane is made in the form of a honeycomb filler, a surface layer glued to the honeycomb structure on both sides and a stabilizing impregnating composition based on polyurethane primers and varnishes, covering the surface layers,

the reverse side of the diaphragm is covered with a damping layer,

the drive of acoustic vibrations is made in the form of at least one exciter of acoustic vibrations, including ferrite parts of the magnetic circuit,

and at least one acoustic vibration exciter is fixed on a flat support frame by means of a bridge, and is attached at one end to the flat membrane within a special line passing along the plane of the rectangular membrane and coming out of any vertex of the rectangular membrane, and ending at a point on the opposite apex of the horizontal side of the membrane, located at a distance of 2/3 of the opposite side of the membrane from the apex horizontally.

Also, in the proposed loudspeaker according to claim 1, the damping layer, which covers the reverse side of the membrane, is made of foam rubber.

The stated solution is illustrated by the following figures:

Figure 1 shows all the main structural elements of a flat loudspeaker,

figure 2 shows a diagram of creating the end edge of the product,

Figures 3-5 show the appearance of a flat loudspeaker,

Fig. 6 shows the end face of the membrane coated with a damping foam rubber coating,

Fig. 7 shows a schematic representation of the geometric proportion of the sides of the membrane, as well as a special line within which the attachment of the pathogens is carried out,

Figure 8 shows a sectional view of the membrane.

In the figures, the positions indicate:

1 - flat support frame,

2 - membrane,

3 - damping foam layer,

4 - the causative agent of acoustic vibrations,

5 - jumper for attaching the exciter to the frame,

6 - spacer for attaching the jumper to the device frame,

7 - acoustic protective fabric,

8 - device for fixing the loudspeaker in the wall hole for surface mounting.

Our proposed built-in flat loudspeaker includes: a flat supporting supporting frame 1 (Fig. 1), made of a metal-plastic composite, a sound-emitting membrane 2 (Fig. 1), (which is a composite with a cellular interior made of aluminum, paper or aramid fiber, and paper with a density of 40-160 g / m2, glued on both sides, impregnated with polyurethane compounds, to give the membrane surface strength and water resistance), a damping foam layer covering the reverse side of the membrane 3 (Fig. 1), an acoustic vibration exciter 4 (Fig. 1) ), including ferrite parts, a bridge for attaching the exciter to the frame 5 (Fig. 1), an acoustic protective fabric 7 (Fig. 1) for protection and aesthetic finishing of the front side of the loudspeaker, fixed to the frame using the method illustrated in Fig. 2, and a device for fixing the loudspeaker in the wall opening for surface mounting 8 (Fig. 1).

In a flat support frame 1 of a square shape, a membrane is installed that is optimal for the distribution of resonant zones of rectangular geometry, close to the proportion of the ratio of length to width as 9 to 5 (Fig. 8). And the vibration exciter is attached at one end to the membrane within a special line passing along the plane of the rectangular membrane and coming out of any vertex of the rectangular membrane, and ending at a point on the opposite vertex of the horizontal side of the membrane, located at a distance of 2/3 of the opposite side of the membrane from the vertex along horizontal, and the membrane is made in the form of a honeycomb filler, a surface layer glued to the honeycomb structure on both sides and a stabilizing impregnating composition based on polyurethane primers and varnishes, covering the surface layers.

Membrane 2 is made as the lightest sandwich structure and is structurally a material that is optimal for the implementation of sound quality indicators in a much wider frequency range. So the membrane consists of a honeycomb filler, which is some kind of honeycomb structure, consisting of various materials such as paper, aramid fiber, aluminum, or other metal with a low specific density. Contains sheets of the surface layer glued to the honeycomb structure from both sides on an adhesive composition that can withstand repeated vibration bending vibrations. It is proposed to use paper with a density of 30 to 125 g per square meter of area as a covering material. Next, a stabilizing impregnating compound is used based on polyurethane primers and varnishes, with which the covering paper is impregnated. If necessary, a layer of acrylic polymer is applied, including micron-scale grinding of mineral and organic substances (quartz, walnut shells, rice and rice husks, etc.).

The constructive solutions used in our loudspeaker are the proportion of the membrane 9 to 5, the method of fastening the membrane to the frame on the vibration isolation tape, as well as the asymmetric fastening of the exciter within the membrane area, made according to a certain scheme (as disclosed above) (Fig. 8). The acoustic vibration drive has ferrite magnetic parts to reduce the frequency and increase the efficiency in the lower register of the audio range. For example, the drive can be made in the form of a plastic case that acts as a support to which a magnetic system is attached, a system for holding a coil in a magnetic gap, fastening to a support frame in the form of a series of threaded holes; parts of the magnetic system, which includes a cylindrical permanent magnet (NeFeB), a ferrite ring that forms the outer perimeter of the annular gap of the magnetic system and a steel washer that holds them together into a single structure; a cylindrical coil wound with copper wire and fixed to the frame in a cylindrical shape made of textolite or other material; systems for holding the coil within the magnetic gap in order to ensure its free reciprocating movement, and consisting of two centering washers of different diameters fixed at some distance from each other (in practice, the distance is from 5 to 15 mm) and made of harsh fabric by pressing in the form of concentrically corrugated discs, with an inner hole fixed to the coil, and an outer perimeter to the support frame; flexible, supplying an electrical signal to the coil, wires sewn into one of the centering washers and soldered at one end to the terminals of the coil, and the other to the external contact group for supplying an electrical signal from the amplifier; a ring for fastening the coil frame to the surface of the sound-emitting membrane; and contacts for supplying an electrical signal.

The proposed recessed flat loudspeaker does not have a back cover. Instead, foam rubber cushioning is provided on the back of the membrane.

The loudspeaker design is open-frame and takes full advantage of the sound quality of flat loudspeaker technology. The design is characterized by an extremely small installation depth, in practice up to 25 mm.

The proposed loudspeaker is based on the ability to generate a transverse acoustic wave (http://selftrans.narod.ru/v2_1/acoustics/acoustics03/acoustics3rus.html) under the action of resonant excitation by surface-traveling waves that arise on the membrane and form frequency-amplitude foci of modulation of opposite vibrations within certain zones on the surface of the sound-emitting membrane. A distinctive feature of this method of sound emission is the formation of a circular sound field around the source, with the properties of uniform distribution of the frequency balance and amplitude of oscillations in the area of action of such a field. The degree of signal attenuation becomes inversely proportional to increasing distance (and not the square of the distance in the case of loudspeakers on conventional speakers). In practice, in the case of built-in acoustics, the radiation pattern is a hemisphere with a source in its center, and the opening angle of the sound beam is 180 ° practically without degradation of the frequency balance and signal amplitude.

Thus, it becomes possible to use a significantly smaller number of flat loudspeakers for a more even sound coverage of spaces and rooms.

Flat square-type loudspeaker FIGS. 3-5. has a plan size of 595 × 595 mm, adapted for installation in a standard cell of 600 × 600 mm of an armstrong type suspended ceiling. The loudspeaker is installed instead of the standard decorative panel in the place of the ceiling where it is supposed to be used. In the case of flush mounting in a frame-panel structure, it is enough to attach the flat loudspeaker to the surface so that its structural elements on the rear side are within the pre-cut mounting hole, and the spring-loaded panel locking mechanism ensures reliable fixation of the cabinet on the back side of the hole edge of all four corners loudspeaker, or at least two opposing ones.

A flat loudspeaker according to the proposed technology can be made in various formats. In the form of a rectangle of different aspect ratios, a square, also include two or more sound-emitting membranes within the same loudspeaker cabinet to increase the panel power or provide a stereo sound mode within the framework of a single panel. It should be especially noted the method of fixing and decorating the fabric covering of the product, which is a technique for organizing the end edge of the loudspeaker case (Fig. 2).

Thus, the advantages of the technology of manufacturing a flat loudspeaker are primarily realized in the field of improving the quality of sound reproduction, increasing the level of psychoacoustic comfort of the consumer of the acoustic signal, as well as ensuring a high degree of ease of installation and operation of built-in acoustic systems.

Achieving a similar or superior technical result requires fewer loudspeakers, fewer cables and wires, lower cost of laying them, higher long-term reliability, and maintenance and repairs cause a minimum of difficulties. The quality of the sound material is improved so much that now you can hear the music exactly as it was conceived and made. Now you do not miss the long-awaited announcement in a noisy station about the time of departure of your train and change of the boarding platform.

Claims (7)

1. A built-in flat loudspeaker, including a housing, a flat membrane and a drive for acoustic vibrations of a transverse acoustic wave, characterized in that the body is made in the form of a flat support frame, and a sound-emitting flat rectangular membrane is fixed on the frame, the membrane is made in the form of a honeycomb filler, a surface layer glued to the honeycomb structure on both sides and a stabilizing impregnating composition based on polyurethane primers and varnishes, covering the surface layers, the reverse side of the diaphragm is covered with a damping layer, the drive of acoustic vibrations is made in the form of at least one exciter of acoustic vibrations, including ferrite parts of the magnetic circuit, and at least one acoustic vibration exciter is fixed on a flat support frame by means of a bridge and is attached at one end to a flat membrane within a line passing along the plane of a rectangular membrane and going out from any vertex of a rectangular membrane, and ending at a point on the opposite apex of the horizontal side of the membrane located at a distance of 2/3 of the opposite side of the membrane from the vertex horizontally. 2. The built-in flat loudspeaker according to claim 1 of the formula, characterized in that the damping layer, which covers the reverse side of the membrane, is made of foam rubber.

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