EP1120994B1 - Flat loudspeaker arrangement - Google Patents

Abstract

The flat loudspeaker arrangement comprises several loudspeakers arranged seamlessly. Each loudspeaker comprising a driver (18) for oscillation generation, sound disk (13) and support stand (14), works on multi-resonance flexible shaft principle.

Description

The invention relates to a flat speaker arrangement.

Plate loudspeakers consist essentially of a plate-shaped membrane (sound plate), a drive system (driver) and a holder. The plate-shaped membrane should be particularly light and particularly resistant to bending. The drive system of the panel loudspeaker usually consists of one or more electromechanical (piezoelectric or preferably electrodynamic) transducers. The holder serves to transmit the weight of the plate-shaped membrane and the drive system to a solid support, without hindering the desired membrane movement.

Plate loudspeakers of conventional design (Planare) are operated underresonant, that is, by design measures is attempted to operate the plate in the frequency range below the first bending vibration resonance. This principle, which is known from the conventional cone loudspeaker, is referred to as a piston loudspeaker. In the case of a planar (fixed loudspeaker), as with the piston loudspeaker, bending vibrations (with a high constructive effort) are prevented.

On the other hand, panel loudspeakers of the latest design are operated in a resonant manner, that is, constructive measures expressly promote the fact that the panel is subject to bending vibration resonances in the operating frequency range. This loudspeaker principle is referred to as a multi-resonant plate loudspeaker. The term "flexural wave loudspeaker" sometimes used in this context is ambiguous in that it could refer to both multi-resonant plate loudspeakers and to bending wave-derived non-resonant absorber plates. The known multi-resonance loudspeakers are consistently plate-shaped, direct-radiating, Even without a housing usable speakers that are installed, for example, as ceiling speakers in suspended ceiling ceilings or operated in the manner of a poster stand with footboard freestanding.

If a cabinet-free multi-resonant plate loudspeaker is brought into the vicinity of a sound-reflecting wall (distance less than plate diagonal, plane-parallel alignment), a general performance drop is observed at low tones (wall effect). One approach to "wall effect" is to shield the multi-resonant panel loudspeaker with a rear flat package. However, the approach is only suitable for small, handy disks with limited bandwidth.

Large flat speakers theoretically have the following advantages: A very low lower limit frequency is achieved by self-shading, with the lowest plate resonances being relatively low as an additional advantage. Furthermore, large flat panel loudspeakers have high sensitivity through the large membrane area because the radiated power is proportional to the membrane area and proportional to the square of the mean effective fast on the membrane. Furthermore, relatively low nonlinear distortions occur due to the small displacement of the drivers. Due to the large surface area, the fast square can be lower for the same emitted acoustic power. Finally, a relatively high maximum power can be delivered due to the large area.

In contrast, the other large flat speakers (planar, electrostatics and magnetostats) all have the serious problem of bundling: the solid angle narrows in the high-frequency range to the square of the ratio of wavelength and membrane diagonal. For example, at a listening distance of five meters, the listener's ear would have to be positioned at five centimeters exactly on the mid-perpendicular of the records. This In practice, however, is rarely observed. For large electrostatics (flat speakers with a soft membrane), the great expense of powerful high-voltage electronics is added. In the case of large magnetostats (likewise flat loudspeakers with a soft membrane), the expense for expensive large specialist magnet drivers and their large weight additionally have a disadvantageous effect. In the case of large planars (flat loudspeakers with a rigid diaphragm), there is the problem of a radical restriction of the operating frequency band: the first bending wave resonance frequency as the relevant frequency limit drops quadratically with the plate diagonal.

Of the four possible principles for large flat panel loudspeakers (planar, electrostat, magnetostat, multi-resonance panel loudspeakers), the multi-resonance panel loudspeakers offer all the advantages of large flat panel loudspeakers (cut-off frequency, sensitivity, distortion, power reserve) without the mentioned disadvantages (bundling effect, high-voltage requirement, expensive flat magnet drivers, limited operating frequency band). However, multi-resonant plate speakers, like all large flat panel loudspeakers in general, have a problem with proper mounting. Freely erected large walls of any kind, require complex support and security structures. The result is that so far only small to medium multi-resonance flat panel speakers are realized, but then no longer offer all the benefits or benefits only to a limited extent.

The document WO 99/12387 A shows a modular arrangement of resonant panel emitters, wherein in each module an acoustic radiator is held by a resilient element in an associated frame member and the outer edges of the frame members are connectable to each other.

The invention has for its object to provide a flat speaker assembly that does not have these disadvantages.

The object is achieved by a flat speaker arrangement according to claim 1. Embodiments and further developments are the subject of dependent claims.

The flat loudspeaker arrangement according to the invention makes use of the load bearing structures (for example walls of buildings) which are already present in the user as a holder, so that large loudspeakers can be realized even with a low material expenditure. It is advantageously no hard-to-control, single and therefore large-scale sound panel used, but individual panel speakers that are applied as about "tiles" simply on the building wall. The pleasant sound of the multi-resonant speakers is mainly based on a bending wave operation above the coincidence frequency. This is achieved, for example, with a cantilevered sound plate (for example a sandwich plate) fixed only at the edge. The flat speaker assembly according to the invention is also characterized by the fact that no "wall effect" occurs that it requires little effort and that it can be operated over the entire hi-fi bandwidth, so both low-frequency piston operation and high-frequency true Biegewellenabstrahlbetrieb.

This is achieved by a flat speaker assembly having a plurality of similar panel loudspeakers that are seamlessly aligned such that the individual panel speakers (after installation on a given, viable mounting surface) have a rigid, shear-resistant edge connection to the respective adjacent panel speakers.

Preferably, these disk speakers each have a driver for generating vibration, a sound board and a holder and operate at high frequency in the multi-resonance bending wave mode.

Particularly favorable are sound panels, which are designed as a self-supporting, low-attenuation sandwich panel with a lightweight, shear-resistant core and a full-surface connected front and / or rear cover sheet. Both the individual panel speakers and the whole, from the individual Panel loudspeakers assembled "wall covering" achieve above all by the installation (installation) the necessary mechanical stability.

Furthermore, it can be provided that the backs of the drivers for mounting the disk speakers are connected to the back of the sound board, wherein the back of the drivers for mounting the disk speakers on a designated surface, such as a wall, are formed. The drivers can be both electrodynamic and piezoelectric and can still be connected by inserting or placing the sound plate back.

Preferably, the sound panel on the back of a profiled, spacing structure (distance profile), which can hold the sound plate cantilevered. The back of the spacer profile can be designed for attachment to a space provided for this purpose (for example, a room wall). As a distance profile several individual spacers can be provided or a full surface fixed to the back of the sound board mat made of soft material (for example, foam) are attached. When using a mat as a distance profile recesses are preferably introduced for the / the driver in this. In this way, the individual panel loudspeakers can be mounted in a very simple manner on a surface provided for this purpose (for example a wall).

Furthermore, the spacer profile can have a circumferential, hermetically sealed bead, which bears against the surface to be fastened, so that a better low-frequency reproduction is achieved.

The resonance volume thus obtained can be provided with a ventilation opening, whereby an even better low-frequency reproduction is achieved. Preferably, the ventilation opening is designed as a bass reflex tube. The bass reflex tube can also be arranged as a floating tube in the sound plate itself, so that the bass reflex tube does not have to be guided by the lateral edge of the distance profile, but a frontal ventilation is achieved. Preferably, a floating tube is firmly anchored in a breakthrough of the sound plate, wherein, for example, the breakthrough in the sound plate, although pre-punched, but still prepared is closed. This gives the user the option of choosing between operation with or without a tube.

An alternative attachment of the bass reflex tube provides to attach it by means of a rear mounting flange on the surface to be fastened, with one or more openings to ensure the connection to the trapped air volume. The breakthrough of the sound plate must be greater than the tube diameter, so that when the tube is inserted, an annular gap remains free. This must preferably be hermetically sealed but vibration decoupled, for example by a thin film, so that the bending vibrations of the sound board are not hindered. Again, the breakthrough of the sound panel can be pre-punched, but not closed, so that the user can plug in the tube at will or not.

Preferably, the disk speakers are interconnected as a bridge network. For example, the plate speakers have the same impedance. The bridge network is now constructed in such a way that the electrical impedance of the overall system is as close as possible to the commercially available speaker impedances (for example 4 to 8 ohms).

Fig. 1

eine erste Ausführungsform einer erfindungsgemäßen Flachlautsprecheranordnung bei einer typischen Anwendung,

Fig. 2

eine zweite Ausführungsform einer erfindungsgemäßen Flachlautsprecheranordnung bei einer typischen Anwendung,

Fig. 3

die erfindungsgemäße Flachlautsprecheranordnung bei einer Transportanwendung,

Fig. 4

einen einzelnen Plattenlautsprecher bei einer erfindungsgemäßen Flachlautsprecheranordnung,

Fig. 5

verschiedene Distanzprofile für einen Plattenlautsprecher bei einer erfindungsgemäßen Flachlautsprecheranordnung,

Fig. 6

einen schwimmenden Bassreflex-Tubus bei einer erfindungsgemäßen Flachlautsprecheranordnung und

Fig. 7

die Verdrahtung einzelner Plattenlautsprecher bei einer erfindungsgemäßen Flachlautsprecheranordnung.

The invention will be explained in more detail with reference to the embodiments illustrated in the figures of the drawing. It shows:

Fig. 1

A first embodiment of a flat speaker arrangement according to the invention in a typical application,

Fig. 2

A second embodiment of a flat loudspeaker arrangement according to the invention in a typical application,

Fig. 3

the flat speaker assembly according to the invention in a transport application,

Fig. 4

a single panel loudspeaker in a flat speaker arrangement according to the invention,

Fig. 5

different distance profiles for a panel loudspeaker in a flat loudspeaker arrangement according to the invention,

Fig. 6

a floating bass reflex tube in a flat speaker assembly according to the invention and

Fig. 7

the wiring of individual panel speakers in a flat speaker arrangement according to the invention.

One aspect of flat panel speakers according to the invention relates to the mounting of the panel loudspeakers by exploiting the stability of existing surfaces such as building walls, room walls and the like. However, another aspect relates to a logistical problem, namely how to adequately handle a wall-sized break-sensitive material loudspeaker in production, transportation and assembly. The Fig. 1 and 2 show typical applications in a simplified listening room 1, such as a living room, a studio, an office, a hall or the like. According to the embodiment Fig. 1 a wall of the listening room 1 is completely serving as a wall radiator system 2 Flat speaker assembly covered. According to the embodiment Fig. 2 a wall radiator system 4 covers only a part of a wall. In both embodiments, the wall radiator systems 2 and 4 are divided into individual wall radiator elements 3, wherein the wall radiator system 2 is composed of sixteen wall radiator elements 3 and the wall radiator system 4 of four individual wall radiator elements 3. After completed installation of the wall radiator systems 2 and 4, the seams between the individual wall radiator elements 3 may be such that they are no longer visible.

Fig. 3 shows a flat speaker assembly according to the invention in terms of logistical problems. A complete wall radiator system 5 is difficult to transport and difficult to install. A flat loudspeaker arrangement according to the invention is subdivided into individual wall radiator elements 3, which can be assembled to form a stack 8, for example, or can be produced and transported one after the other as wall radiator tracks 9.

Fig. 4 shows a wall radiator element (similar to a "tile") in plan view 10 and in perspective 11 without further details. In a more detailed and perspective enlargement, a wall-radiating element is shown in illustration 12, which consists inter alia of a multi-resonance sound plate 13 and a support device 14 (distance profile). The multi-resonant tone plate is supported cantilevered and low in attenuation (for example, by a support 14 formed as a support leg at the corners of the multi-resonant tone plate 13). The multi-resonant tone plate 13 is made of hard, almost brittle material such that as a whole the highest possible flexural rigidity is achieved with the lowest possible mass coating. Hard foam boards (with or without cover layers) or honeycomb sandwich panels are provided for this purpose in the exemplary embodiment. In honeycomb sandwich panels with rear cover layer 15, core 16 and front cover layer 17, the material requirements can be divided into the highest possible Dehnwellengeschwindigkeit the highest possible expansion shaft speed of the cover layer material and the lowest possible average density of the core material in combination with the highest possible shear modulus on average. Together with the driver 18 mounted or recessed on the rear surface of the multi-resonant sound board 13, the arrangement shown represents a complete multi-resonant speaker.

By consistently exploiting the strength and the balanced indoor climate, which is promoted by the massive mounting surfaces (for example, building wall in a building interior), the multi-resonance panel loudspeaker can be produced with the simplest means and therefore cost. In this case, for example, the outer layers of paper and the sandwich core of open-cell foam can be produced. Essential for the properties of such a multi-resonant plate loudspeaker is the distance profile 14, between the self-supporting multi-resonance sound plate 13 and a in FIG. 4 not shown wall is arranged. This device serves as a support for the self-supporting multi-resonant sound plate 13 executed in sandwich technology. The holder must be able to absorb the weight-related static shear force without hindering the vibration of the multi-resonance plate 13 directed normal to the wall. The spacer profile 14 can fulfill its function as defined in many forms. Fig. 5 shows some preferred embodiments.

At the in Fig. 5a embodiment shown solid or soft elastic supports are used as spacers, which are fixed at free positions of the multi-resonance sound plate 13 and the underside are designed for plane-parallel wall fixation. This creates a shallow cavity behind the aligned "tiling layer" of multi-resonant sound plates, which is open at the common edge and has its own low-frequency resonances.

According to the embodiment Fig. 5b is as a spacer profile 14, a soft foam mat 19 with cutouts for from the multi-resonant sound board 13 back outstanding structures such as the drivers 18 are provided. The foam mat 19 is glued to the multi-resonant sound board 13 and formed on the wall side for fixing to a not-shown, intended for mounting wall. This creates a shallow cavity that is open at the common edge and has its own low-frequency resonances behind the aligned "tiling layer" of multi-resonant tone plates.

At the in Fig. 5c shown embodiment, a kind of "box" is provided. A circumferential edge bead 20 serves as a holder of the multi-resonant sound plate 13 and on the other hand generates when mounting the wall radiator element to a (in FIG. 5 not shown wall) regardless of the presence of other wall radiator elements a closed resonant cavity.

The embodiment according to Fig. 5d goes from the embodiment Fig. 5c characterized in that in the peripheral edge bead 20, a lateral bass reflex tube 21 is introduced. The circumferential edge bead 20 in turn serves on the one hand as a holder of the multi-resonant sound plate 13 and on the other he generates when fastening the wall radiator element to the wall a closed resonant cavity, but which is ventilated via an acoustically effective opening. At low frequencies, each of the multi-resonant tone plates will behave like a piston loudspeaker, meaning all surface areas will move in phase. In this case of operation, an enclosed, non-ventilated volume of air would cause a significant increase in the restoring force and thus increase the impedance, thereby hindering the sound power output in the low frequency range. For ventilation except a bass reflex tube and a correspondingly trained horn or a transmission line in question. However, lateral ventilation is only possible in arrangements with a small number of wall radiator elements.

If a wall radiator is constructed from a larger number of wall radiator elements, ventilation towards the front is preferred. Ventilation to the front takes place, for example, by means of openings in the multi-resonance sound panel. Fig. 6 shows such a realization in section. Shown is a part of a wall radiator element with a spacer profile 20 in the form of a circumferential bead. The trapped air volume is ventilated by one or more bass reflex tubes 23, 25. Preferably, two embodiments are used, namely floating tube and fixed tube.

When floating tube is inserted in the simplest case after the wall fixation of the individual, bayed Wandstrahlerelemente a anchored in a matching recess of the sound board bass reflex tube 23 which is internally coupled to the building wall 28 open to the trapped air volume 31. The bass reflex tubes in different wall radiator elements can be tuned differently to ensure a broadband bass boost. The opening of the plate surface by the user can be greatly simplified by production engineering precautions.

In the fixed tube, a hermetically sealed, vibration-isolated annular gap 26 may be provided for decoupling the reflex tube from the floating sound plate in each wall radiator element. After installation of the wall radiator elements, a tube 25 is inserted into all or only selected wall radiator elements. In the exemplary embodiment, a tube with a foot flange 29 is used, which is coupled internally to the building wall 28 through a window 30 to the air volume 31. An aperture ring 24 provides centering and Folienanscluss the respective bass reflex tube. The bass reflex tubes 25 in different wall radiator elements can be tuned differently again in order to ensure a broadband bass boost.

The first resonances of the air volume between the sound board and the building wall show a fast polarization parallel to the wall. The associated scalar pressure distribution is coupled to a diaphragm displacement polarized normal to the wall. The utilization of the large, predetermined by the building wall edge lengths requires that the originally mutually insulated wall radiator elements are low loss coupled together.

If the tonal possibilities of the wall loudspeaker are to be fully utilized, many wall radiator elements are to be coupled in such a way that low-friction, low-pressure equalization is possible. For this purpose, the airtight circumferential partition wall 20 is provided between the tiles to be coupled during assembly with large openings. Another possibility is to make the circumferential tile partition (bead 20) of honeycomb material, wherein the honeycomb cell axes are parallel to the sound plate plane. Then only for the purpose of airtightness even during production applied insulating strip (for example, rigid, airtight contact adhesive tape of appropriate width) must be removed at the butt joint between the wall radiator elements to be coupled.

Since the wall loudspeaker is divided into a plurality of individual wall radiator elements and all wall radiator elements are preferably of similar construction, the loudspeaker system attached to a wall preferably has a periodic structure. This structure is preferably maintained even in the wiring of the individual wall radiator elements.

In Fig. 7a is the electrical connection of wall radiator elements using the example of a loudspeaker system with 4 x 4 = 16 wall radiator elements shown. By means of a matrix-like connection (series and parallel connection), this results in a total impedance which is equal to the impedance of a single system. If the arrangement deviates from a quadratic scheme, correspondingly slight changes in the overall impedance compared with the individual impedance result.

In Fig. 7b is shown in more detail how a wall radiator element 35 can be internally electrically grouped. The driver system in a wall radiator element consists in the simplest case of a single driver, but in higher value systems (as in Fig. 7b In any event, the drive components within a wall radiator element are hardwired together, resulting in a resultant element impedance Z (FIG. 32), such that each wall radiator element follows Wall mounting also works as a loudspeaker and has a commercial electrical impedance. The corresponding drive signal would only have to be applied to the contacts 37 of the respective wall radiator element.

Fig. 7c finally shows a section of the network according to Fig. 7a , It is shown how the wall radiator elements can be individually connected to each other. In particular, these bus connectors 42 do not carry any current in the exemplary embodiment because of the electrical circuit symmetry, for example horizontally extending single-pole bus connectors 42. But if a wall radiator element fails, the symmetry is disturbed. The horizontal bus connectors 42 now carry power and the network works - slightly limited - by redundancy. It is thus a loudspeaker system with static reliability. The wiring is done next to the horizontal bus connectors 42 above beyond with vertical bus connectors 44, wherein the connection of the bus connectors 42 and 44 respectively between horizontal and vertical element connectors 42 and 45, starting from a main terminal 46 for the entire wall speaker. Finally, a vertical bus bridge 43 is provided for connecting the vertical bus.

Claims (16)

1. A flat loudspeaker arrangement with a plurality of similar panel loudspeakers (3), which are arranged seamlessly in a row such that the individual panel loudspeakers (3) have a rigid, shear-resistant edge connection with the adjacent panel loudspeakers (3).
2. A flat loudspeaker arrangement as claimed in Claim 1, characterised in that the individual panel loudspeakers (3) each have a driver (18) for generating oscillations, a sounding plate (13) and a mounting (14, 20) and operate in accordance with the multi-resonance bending wave principle.
3. A flat loudspeaker arrangement as claimed in Claim 2, characterised in that a self-supporting, low damping sandwich plate with a light, shear-resistant core (16) and a front and/or rear cover sheet (17, 15) completely connected thereto is provided as the sounding plate (13).
4. A flat loudspeaker arrangement as claimed in Claim 2 or 3, characterised in that the drivers (18) are connected to the rear side of the sounding plate (13), whereby the rear side of the drivers (18) is constructed for fastening the panel loudspeakers (3) to a surface (28) suitable for this purpose.
5. A flat loudspeaker arrangement as claimed in Claim 2, 3 or 4, characterised in that the sounding plate (13) is provided on the rear side with a spacer profile (14, 19, 20), which can hold the sounding plate (13) in a self-supporting manner.
6. A flat loudspeaker arrangement as claimed in Claim 5, characterised in that the rear side of the spacer profile (14, 19, 20) is formed for fastening to a surface (28) provided for this purpose.
7. A flat loudspeaker arrangement as claimed in Claim 5 or 6, characterised in that a plurality of individual spacer elements (14) are provided as the spacer profile (14, 19, 20).
8. A flat loudspeaker arrangement as claimed in Claim 5 or 6, characterised in that the a mat (19) or soft material fixed to the rear side of the sounding plate (13) over its entire area is attached as the spacer profile (14, 19, 20).
9. A flat loudspeaker arrangement as claimed in Claim 8, characterised in that openings are formed in the mat (19) for the driver(s) (13).
10. A flat loudspeaker arrangement as claimed in Claim 5 or 6, characterised in that the spacer profile (14, 19, 20) has a peripheral, hermetically sealed bead (20) engaging the surface provided for the fastening so that an isolated resonance volume (13) is provided.
11. A flat loudspeaker arrangement as claimed in Claim 10, characterised in that the resonance volume (13) has a ventilation opening (20, 25, 30).
12. A flat loudspeaker arrangement as claimed in Claim 10, characterised in that a bass reflex tube (25, 30) is provided as the ventilation opening.
13. A flat loudspeaker arrangement as claimed in Claim 12, characterised in that the bass reflex tube (25, 30) is arranged in the form of a tube in the sounding plate (13) arranged to move with it.
14. A flat loudspeaker arrangement as claimed in Claim 11, characterised in that the ventilation opening (21, 25, 30) is attached by means of a mounting flange on the rear surface to the surface (28) provided for fastening, whereby one or more openings (26) ensure the connection to the enclosed air volume (31).
15. A flat loudspeaker arrangement as claimed in Claim 14, characterised in that an air gap, which is sealed in a hermetic and oscillation-isolating manner, is provided in the sounding plate (13) such that the bending oscillation of the sounding plate (13) is not restrained.
16. A flat loudspeaker arrangement as claimed in Claim 1 to 6, characterised in that the panel loudspeakers (13) are connected together in the form of a bridge network (32, 33, 34, 35).

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