EP1078551B1 - Panel loudspeaker - Google Patents

Abstract

The invention relates to so-called panel loudspeakers (11) working according to the multiresonance principle. Said loudspeakers are generally formed by a core layer (13) and at least one outer layer (14.o, 14.u). The outer layers (14.o, 14.u) are connected to the core layer (13). A periphery is also provided (12) enclosing the panel loudspeaker (11) at a lateral distance (A). The panel loudspeaker is connected to the periphery (12) by means of connecting elements (17, 17'). Although good reproduction results can be obtained in the mid and high audio frequencies with the panel loudspeakers (11) described above, undesired large panel surfaces are known to be required for good low frequency reproduction. When such panel surfaces are not used, the lowest panel resonances ensuring bass reproduction are shifted towards the midfrequencies. Hence, the invention aims at providing a panel loudspeaker (11) exhibiting improved acoustic reproduction in the low frequency range despite a relatively smaller panel surface. According to the invention, this is achieved in that the connecting elements (17 17') are subjected to mechanical tension when they are connected to the periphery (12) resulting in supplementary particularly low frequency drum resonances in addition to the existing low frequency panel resonances, which can be modulated by the tension in the connecting elements (17, 17').

Description

Technical field

The invention is concerned with panel loudspeakers, in particular with the Improvement of the low-frequency radiation of such record speakers.

State of the art

For example from WO-A-9 709 840 or EP-A 0 924 960 (prior art according to Article 54 (3) EPC) record speakers are known, which after the Multi-resonance principle work and also under the term "distributed mode Loudspreakers "are known. Such arrangements are essentially formed by a flat panel and at least one drive system, wherein the panel is vibrated when the drive system low-frequency, electrical sound signals are supplied. Depending on The drive systems for these arrangements are used for one or a plurality of electromagnetic drivers (shakers) is formed. The latter does not rule out the possibility of piezoelectric bending vibrators exclusively or in combination with the aforementioned Shakers as Drive systems are used.

In order to operate the record speakers properly, they are included Connection elements connected to a periphery. This periphery allows on the one hand, the outer holding of the entire record speaker and provides on the other hand, a favorable for the sound reproduction of the weight of the Panels and the drive system or systems used safely.

Characteristic of such sound reproducing arrangements in the form of Record speakers is that from a critical lower cut-off frequency "Bending wave radiation" is possible, the bending waves in Record speakers for sound radiation with frequency-dependent direction to lead. A section through a created directional diagram shows a main lobe, whose direction is frequency dependent.

The panel of the panel loudspeaker is constructed according to the sandwich principle in that, for example, two opposing surfaces of a very light core layer, each with a cover layer that is thin in comparison to the core layer, for example. Bonding are connected. In order for the record speaker to have good sound reproduction properties, the material for the cover layer must have a particularly high expansion wave speed. Suitable cover layer materials are, for example, thin metal foils or fiber-reinforced plastic foils. Special requirements are also placed on the core layer, because this layer must above all have a particularly low density (for example 20 to 30 kg / m ³⁾ . Furthermore, the core layer should be able to absorb high shear stresses normal to the cover layers. Ultimately, the modulus of elasticity in the direction normal to the cover layers must be sufficiently large, while a very low modulus of elasticity does not interfere parallel to the cover layers. In this respect, the core layer can exhibit anisotropic or isotropic behavior. For example, honeycombs made of light metal alloys or resin-impregnated fiber-reinforced papers (anisotropic) and rigid foams (isotropic) have proven themselves as ultra-light core layer structures.
In order to emit sound waves by means of an arrangement described above, it is necessary to connect the panel to a drive system which then deforms the panel in a wave shape perpendicular to the plane of the cover layers. In order to achieve this, magnet systems known from the prior art are generally used by attaching them to the panel or also integrating them into the panel.

To maximize the efficiency of record speakers after The multi-resonance principle should "free" the edge of the panel if possible be, i.e. the transverse vibrations spreading on the panel should be neither fixed nor damped in the edge area of the panel.

Although in the middle and High range can be achieved, it has been shown that undesirably large panel areas are required for good bass reproduction are. If such panel surfaces are not provided, move them the deepest record resonances carrying the bass reproduction in the The central region.

The invention is therefore based on the object of specifying plate loudspeakers, which improved despite relatively small panel areas Have sound reproduction performance in the low frequency range.

Presentation of the invention

This object is achieved with the features specified in claim 1. Advantageous training and further developments can be found in claims 2 to 8.

Is the respective panel of the plate loudspeaker with the periphery by means of below connected mechanical tension connecting elements, so arise in addition to the existing low-frequency plate resonances further, particularly low-frequency drum resonances. This can be done through the Tension in the fasteners can be matched.

At this point it should be pointed out that the used Materials and the degree of preload of the respective fasteners decisive influence on the reproducibility of low-frequency sound signals to have.

It is also not necessary that the tensioned connecting elements in different spatial directions must have the same voltages.

According to claim 2, the respective connecting elements of one or also formed two cover layers by the respective cover layers Spanning lateral distance to the periphery is a very inexpensive and in the production very easily realizable unit from periphery and Panel created.

If the respective periphery is formed by a frame, can such arrangements with little effort with other objects can be connected, because the necessary for the generation of the necessary voltage in the Cover layers and / or connecting elements already work can be carried out in the factory with high manufacturing quality.

The plate loudspeakers according to the invention are also not merely monotonic Sound reproduction arrangements can be used. Rather, it is according to claim 4 also possible to make a plurality of panel speakers to a larger one Combine baffle without the individual panel directly with a peripherals not excited by transducers. Rather, in Connection with the invention shown that the otherwise for connection to a peripherals that are not excited (e.g. a Ralunen) Connecting elements for the mutual and decoupled connection of used adjacent panels of a larger baffle can be. Is this bigger baffle -as already in connection with Claim 1 described - also by means of corresponding connecting elements For example, associated with a ralune, can be found in these Fasteners prevailing tension also the tension in the Fasteners can be set between the panels of a such baffle are arranged. In this case, the fine adjustment can be used decoupled and tensioned connection between two adjacent panels through a corresponding size and / or material selection for the respective Connection element can be made.

A particularly simple adjustment of the tension in the cover layers and / or connecting elements is given if according to claim 5 respective connecting elements on their edges, which are connected to the periphery are connected, are provided with clamping strips if the periphery with edges is provided against which the tensioning strips rest when the panel is connected to the periphery connected, and if one is not yet connected to the periphery Panel the distances between the tension bars and through the center coordinate lines of the respective plate loudspeaker are smaller than the distances between the edges and also through the center the coordinate lines running on the periphery. In this case, Tension bars associated with the edges turns out without great Effort very evenly and over the respective distance ratios definable tension in the cover layers and the connecting elements of the respective plate loudspeaker.

Particularly good reproduction ratios of the live Fasteners are achieved when the trained Record speakers are used to reproduce low-frequency sound signals. However, this does not mean that prestressed connecting elements only the Bass transfer improvements are reserved. Rather are tense Cover layers and / or connecting elements also for mid-range and Broadband panels can be used.

Are according to claim 7 also the areas of the outer layers, which with the Core layer connected, under mechanical tension, is special in the case of thin metal foils, the expansion wave speed for the cover layers elevated.

The mechanical tension of the connecting elements and / or the Particularly low-frequency resonances can be generated in their cover layers Vibration amplitude can be reduced by the according to claim 8, respectively parts under mechanical tension (cover layers and / or Connection elements) are provided with damping elements 30.

According to claim 9, the mechanical tension Fasteners and the cover layers may be different. Thereby damping values of different sizes can be very easily with the realize different parts.

Brief presentation of the figures

Figur 1

einen Plattenlautsprecher in Draufsicht;

Figur 2

einen weiterer Plattenlautsprecher in Draufsicht;

Figur 3

einen Plattenlautsprecher gemäß Figur 1 in Seitenansicht;

Figur 4a u. b

eine weitere Seitenansicht eines Plattenlautsprechers; und

Figur 5a u. b

eine weitere Seitenansicht eines Plattenlautsprechers.

Show it:

Figure 1

a plate speaker in plan view;

Figure 2

another plate speaker in top view;

Figure 3

a plate speaker according to Figure 1 in side view;

Figure 4a u. b

another side view of a plate speaker; and

Figure 5a u. b

another side view of a plate speaker.

Ways of Carrying Out the Invention

The invention will now be explained in more detail with reference to the figures. 1 shows a sound reproduction arrangement 10 in the form of a Record speaker shown, which after the already explained "Bending shaft principle" works. This arrangement 10 is provided by a panel 11 and a periphery 12 is formed.

The panel 11, which is shown in more detail in FIG. 3, is sandwich-shaped constructed by a core layer 13, which in the present case is a honeycomb structure has, on two opposite surfaces, each with a thin Sealing layer 14o, 14u is provided.

The periphery 12 is in the embodiment shown in Figure 1 by a an opening 15 provided installation wall 16 is formed. In this opening 15 it is Panel 11 used. The connection between the panel 11 and the Periphery 12 in the form of the built-in wall 16 is realized such that a Connecting element 17 with the cover layer 14.o and the installation wall 16 connected is. From Figure 1, which is a top view of a record speaker 10 shows, can also be seen that the connecting element 17 in one piece is formed and the mutual distance A between each other facing edges 24 and 24 'of panel 11 and opening 15 completely covered.

The outstanding results in sound reproduction are achieved in that the cover layers 14, o, 14.u of the panel 11 under mechanical tension stand. The tension in the connecting elements 17, which in FIG the double arrow P shown is indicated can be shown in FIG Embodiment can be achieved in that after inserting the panel 11 into the opening 15 the areas of the Connecting element 17 before connecting it to the installation wall 16 in x and y direction (Figure 1) can be stretched.

In connection with Figures 1 and 3 is only for the sake of completeness 1 that 18 in FIG. 1 denotes drivers, which vibrate the panel 11, and that by means of the in Fig. 3rd connecting element 17 "shown in dashed lines if necessary a further - also tensioned - connection between the installation wall 16 and the panel 11 can be produced.

In addition, in Fig. 3 by the dashed double arrows P4 indicated that also the cover layers connected to the core layer 13 14.u., 14.o are under mechanical tension, in which case the degree of mechanical stress of the connecting elements 17 and the Cover layers 14, u., 14.o need not necessarily be the same size. With the Reference numerals 30 are designated in FIG. 3 damping elements, which may be used for Limitation of the vibration amplitude when under mechanical tension standing connecting elements 17, 17 'and / or cover layers 14.o, 14.u for Can come into play.

In Figure 2, a plate speaker 10 is shown, which a plurality of Panels 11 has. In relation to the middle panel 11 ', this means that the the panel 11 'surrounding panels 11' 'form the periphery thereof. Furthermore in this embodiment, the periphery 12 for all panels of one independent Ralunen 19 formed, which frames all panels 11. The Use of an independent frame 19 in one or more Panels 11 has the advantage that the tension in the connecting elements 17th not only when connecting the panel or panels 11 directly to the respective one Installation location must be carried out, but very simple and factory can be set precisely if the or the respective plate speakers 10 can only be delivered together with a frame 19.

Furthermore, the top view according to FIG. 2 shows that the panels 11 different dimensions as well as different distances with each other or with the frame. The different dimensions of the panels 11 are due to the fact that the various panels 11 of the in 2 shows the arrangement 10 shown as a so-called area radiator for different audio frequency ranges are optimized. That kind of Training makes it a decoupling of the various panels 11 also required that the distances between the individual panels 11 or the distances of the panels 11 to the frame 19 the corresponding Playback area of the affected panels 11 can be adjusted. Only the For the sake of completeness it should be noted that because of the different Frequency ranges trained panels 11 optimizes the mechanical tension in the cover layers (not shown in more detail in FIG. 2) of the various panels 11 is also adapted to the corresponding reproduction purposes.

In the exemplary embodiment shown in FIG. 2, use is also made independent connecting elements 17 dispensed with. Rather, the panels are 11 with each other or with the Ralunen 19 exclusively by means of the cover layer 14o connected. This type of connection is shown in more detail in FIGS. 4b and 5b and will be explained in connection with these figures.

An exemplary embodiment for a frame 19 is shown in FIG. 4a. Above of the frame 19, a panel 11 is arranged. In contrast to that in FIG. 3 Panel 11 shown, the top layer is slightly above the edges 24 of the Core layer 13 over. In addition, at the edges 24 "of the cover layer 14.o Tension bars 20 attached. If the cover layer 14.o is now in the arrow direction P1 deformed elastically by external forces and in this state in Lowered direction P2 on the frame 19, arise when the top layer 14.o abuts the frame, conditions shown in Figure 4b. This The illustration also shows that the panel 11 is used exclusively by means of the Cover layer 14.o is connected to the frame 19 and that the clamping strips 20th rest on the lateral edges 21 of the ralunens when the movement along arrow direction P2 is complete. Because before assembly accordingly the ratios shown in Figure 4a, the distance A 'between the two Tension bars 20 is less than the distance A '' between two opposite lying edges 21 of the frame 19, builds after assembly, thanks to the restoring forces in Area 17 'of the cover layer 14.o the desired mechanical tension (indicated by the double arrows) when the one shown in FIG. 4b Condition is reached.

Contrary to the representation according to FIGS. 4a and 4b, the cover layer 14.o is not included the core layer 13 is connected, the stress in the entire cover layer 14.o built up. To the beneficial effects of the transfer to obtain the tensioned cover layer 14.o, then only the core layer 13 be connected to the cover layer 14.o.

Figure 5a and b shows a further embodiment of a mechanical Tensioned connection between a panel 11 and a frame 19. Here, in contrast to the representation according to FIGS. 4a and b, the distance A ' between the clamping bars 20 equal to the distance A "between the opposite lying edges 21 of the frame 19. These spacing relationships make it the top view 14.o in FIG. 5a for establishing the connection is also superfluous with the frame 19 (Figure 5b) one shown in connection with Figure 4a Suspend force action (P1). The required tension in the areas 17 ' the cover layer 14.o is brought about by the fact that after the cover layer 14.o on the frame 19 or the tensioning strips 20 on the edges 21 without tension abut (shown on the left in Figure 5b), one or both Tension bars 20 are rotated in the direction of arrow P3, so that no longer Long side 22, but the narrow side 23 of the clamping bar 20 at the edge 21 the frame 19 abuts (shown on the right side in Figure 5b).

Should not only a tension in the areas 17 'of the cover layer 14.o, but can also be brought about in the entire top view 14.o, only that Cover layer 14.o in accordance with the explanations for FIGS. 4a to 5b connected to the frame 19 and then the core layer 13 to the then completely tensioned cover layer 14.o for example by gluing be attached. For a subsequent connection of core layer 13 and Cover layer 14.o as a separate step in a fully tensioned Cover layer 14.o can be dispensed with if the unit consists of a core layer 13 and cover layer 14.o according to FIGS. 4a to 5b, as long as the adhesive, which the connection between the cover layer 14.o and the Core layer 13 produces, has not yet set.

For the sake of completeness, it should be noted that in the exemplary embodiments both according to FIGS. 4a to 5b with a corresponding modification Cover layers 14.o and 14.u can be under mechanical tension.

Claims (8)

1. A panel loudspeaker
   having a core layer (13) and at least one covering layer (14 top, 14 bottom),
   having a periphery (12) which surrounds the panel loudspeaker (11) with lateral spacing (A), and
   having connection elements (17, 17'') which connect the panel loudspeaker (11) to the periphery (12), wherein the connection elements (17, 17'') are subjected to mechanical stress in the state connected with the periphery (12),
   characterised in that the regions of the covering layers (14 top; 14 bottom) which are connected to the core layer (13) are also subjected to mechanical stress.
2. A panel loudspeaker according to Claim 1,
   characterised in that the connection elements (17, 17'') are formed by the covering layer or layers (14 top; 14 bottom) of the respective panel loudspeaker (11), by at least one of the covering layers (14 top; 14 bottom) of the respective panel loudspeaker (11) being guided to the periphery (12).
3. A panel loudspeaker according to Claim 1 or 2,
   characterised in that the periphery is formed by a frame (19).
4. A panel loudspeaker according to Claim 1 or Claim 2,
   characterised in that the periphery (12) of the panel loudspeaker (11) is formed by at least one panel (10).
5. A panel loudspeaker according to Claim 1 or Claim 2,
   characterised in that the respective connection elements (17, 17") are provided with tensioning bars (20) at their edges (24") which are connected to the periphery (12),
   in that the periphery is provided with edges (21) against which the tensioning bars (20) abut when the panel loudspeaker (11) is connected to the periphery (12),
   and in that in the case of a panel loudspeaker (11) not yet connected to the periphery (12), the distances (A') between the tensioning bars (20) and the coordinate lines (x, y) running through the centre point of the respective panel loudspeaker (11) are less than the distances (A") between the edges (21) and the coordinate lines (x, y) also running through the centre point of the periphery (12).
6. A panel loudspeaker according to one of Claims 1 to 5,
   characterised in that the panel loudspeaker (11) is a bass panel for the reproduction of low-frequency sound.
7. A panel loudspeaker according to one of Claims 1 to 6,
   characterised in that the core layer (13) and/or the connection elements (17, 17'') are provided with damping elements (30).
8. A panel loudspeaker according to Claim 7,
   characterised in that the mechanical stress in the connection elements (17, 17'') is different to the mechanical stress in the covering layers (14 top, 14 bottom) subjected to tension.

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