EP2158789B1 - Diaphragm arrangement for an air motion transformer (amt), and sound converter comprising such a diaphragm arrangement - Google Patents

Abstract

The invention relates to a diaphragm arrangement (16, 26, 39, 47, 62) for an air motion transformer (AMT). Said diaphragm arrangement (16, 26, 39, 47, 62) comprises at least one substantially meander-shaped diaphragm (16a) as well as air pockets (23, 59, 60) for generating sound as a result of the meander-shaped design of the at least one diaphragm (16a). In order to improve the radiation behavior of the diaphragm arrangement and at least reduce the concentration of sounds, the diaphragm arrangement (16, 26, 39, 47, 62) encompasses several diaphragm segments (A, B, C; a, b, c) which are arranged and/or designed such that the diaphragm arrangement (16, 26, 39, 47, 62) has a substantially common acoustic center.

Description

The invention relates to a membrane arrangement for an air-motion transformer (AMT), wherein the membrane arrangement has at least one substantially meander-shaped membrane and the membrane arrangement has air pockets for generating sound through the meandering design of the at least one membrane. Furthermore, the invention relates to a sound transducer with such a membrane arrangement.

Such membrane arrangements are used in the prior art in sound transducers, in particular in so-called AMT loudspeakers. The Air-Motion-Transformer (abbreviated to AMT) is an original of Dr. med. Oskar Heil developed sound transducer. Such an air-motion transformer has a meandering or accordion-like folded membrane. By this shaping of the membrane air pockets are formed. These air pockets are widened and narrowed for pressing out or for sucking in air and thus for generating sound. For this purpose, the membrane arrangement is vzw. in operative connection with a suitable device. Vzw. are arranged on the flanks of the air pockets tracks. The preferably arranged in a magnetic field membrane or the air pockets are excited to generate sound by an alternating current is passed through the tracks. The flanks of the air pockets are moved against each other, wherein the air is forced out of the air pockets or sucked into these air pockets inside.

Air-motion transformers can be used in particular in hi-fi speakers as a tweeter in the frequency range from about 1 kHz to a maximum of about 25 kHz. Due to the small moving mass of the membrane, Air Motion Transformers are characterized by their excellent impulse behavior, since an AMT loudspeaker can reproduce a pulsed signal with only very low input or decay processes.

[State of the art]

The international patent application WO 99/07183 A1 discloses an AMT loudspeaker with a diaphragm configured to emit different frequencies of sound.

The international patent application WO 01/13678 A1 discloses a series of electrostatic and electro-dynamic loudspeakers with membrane assemblies stiffened with web-shaped elements in a particular direction. However, this patent application does not show an AMT speaker.

Fig. 1 shows a schematic representation of a known in the prior art membrane assembly 1 for a not shown in detail, electrodynamic mixing Sound converter, here a speaker. The here meander-shaped membrane assembly 1, which here has a single membrane 1a, takes this form substantially in its operating state, said membrane assembly 1 then vzw. is arranged between two pole plates, not shown here in an air gap. The membrane assembly 1 is first prepared as a sheet-like element, the illustrated interconnects 2 vzw. be formed on the membrane 1a by means of appropriate etching.

Clearly visible are a plurality of wave crests 3 and troughs 4 and the wave crests 3 and the wave troughs 4 interconnecting and opposite edges 5, on which the conductor tracks 2 are arranged. How out Fig. 1 is clearly visible, a plurality of air pockets 6 are formed by this arrangement. By the arrows shown on the tracks is in Fig. 1 a current I flowing through the printed conductors 2 is indicated. Furthermore, a static magnetic field is indicated by the arrows B.

The mode of operation of the membrane arrangement 1 known in the prior art will now be described with reference to FIG FIGS. 2 and 3 explained. In the Fig. 1 shown rest position of the membrane assembly 1 is in the FIGS. 2 and 3 each shown in dashed lines. The FIGS. 2 and 3 show with the solid lines the excited state of the membrane 2 and the air pockets 6 in the open and closed position. In detail:

Fig. 2 shows that the flanks 5 of the membrane assembly 1 move in the direction of the arrows C ₁ . The air pockets 6a, 6b, 6c and 6d increase in width, ie these air pockets 6a, 6b, 6c and 6d are opened, so that air is sucked into these air pockets 6a to 6d according to the arrows E. Air pockets 6e, 6f, and 6g are arranged between the air pockets 6a to 6d, open to the other side. These air pockets 6e to 6g adjacent to the air pockets 6a to 6d are correspondingly reduced in width - or are closed - so that, according to the arrows A, the air is forced out of these air pockets 6e to 6g. (Arrows A: air outlet, arrows E: air intake).

Fig. 3 now shows the membrane assembly 1 in the reverse deflection position of the flanks 5. The flanks 5 move in the opposite direction, this being indicated by the arrows C2. The flanks 5 of the air pockets 6a, 6b, 6c and 6d move towards each other, so that these air pockets 6a to 6d narrow and the air is forced out of these air pockets 6a to 6d (see arrows A). The air pockets 6e, 6f and 6g are widened, so that air is sucked into these air pockets 6e, 6f and 6g (see arrows E).

Fig. 4 shows an AMT transducer 15 with in the Fig. 1 to 3 The membrane assembly 1 is arranged between two pole plates 7 and 8 in an air gap 9. The membrane assembly 1 is clamped in a frame, wherein only the two frame parts 10a and 10b can be seen from the frame. The frame with the frame parts 10a and 10b is connected to two side parts 11a and 11b. The side parts 11 a and 11 b in turn carry the pole plates 7 and 8.

Fig. 5 shows that the pole plate 8 has a plurality of sound openings 12. The sound holes 12 are formed in the form of slits 12a extending in the horizontal direction. Through the slots 12a, the sound generated by the membrane assembly 1 can escape from the sound transducer 15.

By periodically narrowing and widening the air pockets 6 are emitted from the membrane assembly 1 sound waves. The sound waves are - like all waveforms - broken and bent. The strength of the diffraction of the sound waves depends on their wavelength. Long waves, ie low notes, become less than short waves, high notes, bent and broken. This frequency-dependent behavior is summarized under the term radiation behavior. Loudspeakers and thus also air-motion transformers therefore have a different emission behavior at different frequencies. The low frequencies are rather spherical radiated and tend to spread equally in all directions. With increasing frequency, the sound waves show an ever stronger concentration. High frequencies are almost only radiated in a certain direction.

In Fig. 4 is the horizontal bundling and in Fig. 6 For example, the vertical focusing of the sound waves 13 and 14 is shown once for low frequency sound waves 13 and once for high frequency sound waves 14. The sound waves 13 having a low frequency are radiated in an emission cone with an aperture angle relative to the ideal emission axis S. The emission axis S extends perpendicularly and centrally to the membrane arrangement 1. The sound waves 14 having a high frequency are radiated essentially only in the direction of the emission axis S as plane and parallel wavefronts.

In many cases, this bundling of the sound at high frequencies is undesirable. Among other things, it is crucial for the listening impression how the sound is emitted away from the ideal radiating axis (Hörachse), because not all listeners are always in the direction of the horn axis. Ideally, therefore, a loudspeaker should play all frequencies identically loud in every direction. In practice, a bundling of sound occurs but especially in the mid / high range and is dependent on the frequency. The all-round radiation capability can therefore be restricted, in particular in the case of membrane loudspeakers. With increasing frequency, a bundling of the radiated sound occurs, for example, in the horizontal and vertical directions, as in Fig. 4 and 5 is shown.

The invention is therefore based on the object to design a membrane arrangement and further develop that the radiation behavior of the membrane assembly is improved and the sound bundling is at least reduced, in particular for the high frequencies.

The above object is solved by the subject of the appended claims. In this case, the membrane segments are arranged or formed in such a way that the sound waves emitted by the membrane segments are superimposed in such a way that the overall sound-for the listener-appears to come from an acoustic center. This allows a precise picture of the sound to reach. If two speakers are used, it can also achieve a precise stereo location. The acoustic center preferably lies on the emission axis or in the corresponding emission plane of the membrane arrangement. As the following statements will show, there are now different possibilities to realize the "membrane segments". On the one hand, the corresponding "membrane segments" may be formed as subregions of a single membrane, but on the other hand it is also possible that several individual vzw. Meander-shaped membranes are summarized to form a membrane assembly accordingly. It is crucial that the membrane segments thus formed are arranged and / or configured in this way - or which will also show the following statements - then be controlled so that the membrane arrangement itself has a common acoustic center.

The individual membrane segments are in turn preferably arranged symmetrically with respect to the emission axis or emission plane of the membrane arrangement. For example. For example, a middle membrane segment and at least one outer membrane segment can be arranged on both sides of the middle membrane segment. Preferably, the middle diaphragm segment for reproducing a high-frequency range and the outer diaphragm segments are then designed for reproducing a low-frequency range.

The subdivision of the membrane assembly into a plurality of membrane segments also has the advantage that the omnidirectional behavior is improved since the limit for an acceptable omnidirectional behavior is given if the extent of a membrane segment in one direction is less than half the wavelength of the frequency to be generated. As the frequency to be radiated increases, therefore, small membrane expansions are advantageous. The subdivision of the membrane assembly in membrane segments can be carried out in vertical and / or horizontal extension of the membrane assembly (in a towering erected membrane assembly). For reproducing low frequencies, the membrane arrangement preferably has a correspondingly large area. The deeper the frequency to be transmitted is selected, the larger is preferably the total membrane area for reproducing the lowest frequency.

Details may be described below with reference to the embodiments. As a result, however, the aforementioned disadvantages are avoided and achieved corresponding advantages.

Fig. 1

in schematischer Darstellung den Aufbau einer im Stand der Technik bekannten Membrananordnung,

Fig. 2

die Membrananordnung aus Fig. 1 in schematischer Darstellung von der Seite mit den Bewegungen der Flanken in einer ersten Richtung,

Fig. 3

die Membrananordnung aus Fig. 1 in schematischer Darstellung mit Bewegungen der Flanken in einer zweiten, entgegengesetzten Rich- tung,

Fig. 4

in schematischer Darstellung einen Schallwandler mit der montier- ten bekannten Membrananordnung aus Fig. 1 in Draufsicht,

Fig. 5

den Schallwandler aus Fig. 4 in einer schematischen Vorderansicht,

Fig. 6

den Schallwandler aus Fig. 5 in einer schematisch stark vereinfach- ten Seitenansicht,

Fig. 7

in schematischer Darstellung eine erste Ausführungsform eines bekannten Schallwandlers in Draufsicht,

Fig. 8

den Schallwandler aus Fig. 7 in schematischer Vorderansicht,

Fig. 9

den Schallwandler aus Fig. 7 in einer schematisch stark vereinfach- ten Seitenansicht,

Fig. 10

in schematischer Darstellung eine zweite Ausführungsform eines bekannten Schallwandlers in Vorderansicht,

Fig. 11a

den Schallwandler aus Fig. 10 in einer schematischen Draufsicht,

Fig. 11b

den Schallwandler aus Fig. 10 in einer schematisch stark verein- fachten Seitenansicht,

Fig. 12

eine Detailansicht eines Teilbereichs eines ersten Membransegments in Draufsicht in schematischer Darstellung,

Fig. 13

eine Detailansicht eines Teilbereichs eines zweiten Membranseg- ments in maximal komprimiertem Zustand in schematischer Darstel- lung,

Fig. 14

eine weitere Detailansicht des Teilbereichs des zweiten Membran- segments in einem der Fig. 13 nachfolgendem Zustand in schemati- scher Darstellung,

Fig 15

eine Ausführungsform eines erfindungsgemäßen Schallwand- lers in schematischer Draufsicht,

Fig 16

ein erstes, elektrisches Schaltbild für den Schallwandler aus Fig. 15,

Fig. 17

ein zweites, elektrisches Schaltbild für den Schallwandler aus Fig. 15,

Fig. 18a

eine weitere Ausführungsform für einen erfindungsgemäßen Schall- wandler in schematischer Draufsicht,

Fig. 18b

ein elektrisches Schaltbild für den Schallwandler aus Fig. 18a,

Fig. 19

eine andere Ausführungsform für einen erfindungsgemäßen Schall- wandler in schematischer Draufsicht,

Fig. 20

ein elektrisches Schaltbild für den Schallwandler aus Fig. 19

Fig. 21

ein weiteres elektrisches Schaltbild für den Schallwandler aus Fig. 19,

Fig. 22a

eine weitere Ausführungsform für einen erfindungsgemäßen Schall- wandler in schematischer Draufsicht, und

Fig. 22b

ein elektrisches Schaltbild für den Schallwandler aus Fig. 22a.

There are now a variety of ways to design the membrane assembly according to the invention or a sound transducer in an advantageous manner and further. For this purpose, reference may first be made to the claims subordinate to claim 1. In the following, several embodiments of the invention with reference to the following drawings and the associated description are explained in detail. In the drawing shows:

Fig. 1

a schematic representation of the structure of a known in the prior art membrane assembly,

Fig. 2

the membrane assembly Fig. 1 in a schematic representation of the side with the movements of the flanks in a first direction,

Fig. 3

the membrane assembly Fig. 1 in a schematic representation with movements of the flanks in a second, opposite direction,

Fig. 4

in a schematic representation of a sound transducer with the assembled known membrane arrangement Fig. 1 in plan view,

Fig. 5

the sound transducer Fig. 4 in a schematic front view,

Fig. 6

the sound transducer Fig. 5 in a schematically simplified side view,

Fig. 7

a schematic representation of a first embodiment of a known sound transducer in plan view,

Fig. 8

the sound transducer Fig. 7 in a schematic front view,

Fig. 9

the sound transducer Fig. 7 in a schematically simplified side view,

Fig. 10

a schematic representation of a second embodiment of a known sound transducer in front view,

Fig. 11a

the sound transducer Fig. 10 in a schematic plan view,

Fig. 11b

the sound transducer Fig. 10 in a schematically simplified side view,

Fig. 12

a detailed view of a portion of a first membrane segment in plan view in a schematic representation,

Fig. 13

a detailed view of a portion of a second membrane segment in the maximally compressed state in a schematic representation,

Fig. 14

a further detailed view of the portion of the second membrane segment in one of Fig. 13 following state in a schematic representation,

Fig. 15

An embodiment of a transducer according to the invention in a schematic plan view,

FIG. 16

a first, electrical circuit diagram for the sound transducer Fig. 15 .

Fig. 17

a second, electrical circuit diagram for the sound transducer Fig. 15 .

Fig. 18a

a further embodiment of a sound converter according to the invention in a schematic plan view,

Fig. 18b

an electrical circuit diagram for the transducer Fig. 18a .

Fig. 19

another embodiment of a sound converter according to the invention in a schematic plan view,

Fig. 20

an electrical circuit diagram for the transducer Fig. 19

Fig. 21

another electrical circuit diagram for the transducer Fig. 19 .

Fig. 22a

a further embodiment of a sound converter according to the invention in a schematic plan view, and

Fig. 22b

an electrical circuit diagram for the transducer Fig. 22a ,

In Fig. 7 is a sound transducer 15 with a membrane assembly 16, namely shown here with a single membrane 16a. The sound transducer 15 is a so-called air-motion transformer (AMT), namely designed here as a speaker.

The membrane 16a is meander-shaped and arranged between two pole plates 17 and 18 in an air gap 19. The membrane 16 a is vzw. initially produced as a sheet-like element, wherein the conductor tracks, not shown here vzw. be formed by means of appropriate etching on the membrane 16a and the membrane 16a vzw. lying in a plane between the pole plates is arranged.

Clearly visible are a plurality of wave crests 20 and troughs 21 and the wave crests 20 and wave troughs 21 interconnecting and opposing flanks 22, on which the conductor tracks, not shown here are arranged. In this case, there is essentially a corrugation valley 21 between two corrugation peaks 20 and a corrugation peak 20 between two adjacent corrugation troughs 21, so that a corresponding "accordion shape" is created as indicated in the respective figures. How out Fig. 7 clearly is, are formed by this arrangement, a plurality of air pockets 23 for generating sound.

Further, by the pole plates 17 and 18, a vzw. static, not shown magnetic field or an electrostatic magnetic field generated. On the non-illustrated traces act sideways forces when the traces are traversed by a current. In particular, the current may be an alternating current, which may in particular be proportional to an audio signal. In the operating state, the air pockets 23 of the membrane arrangement 16 or of the membrane 16a shown here are compressed and widened by the lateral forces - depending on the direction of the current in the printed conductors - whereby sound waves 24 are generated by the membrane arrangement 16. Adjacent flanks 22 of the membrane 16a move either towards or away from each other.

The disadvantages described above are now avoided in that the membrane assembly 16 several membrane segments - here in Fig. 7 comprising three membrane segments - A, B and C, wherein the membrane segments A, B and C are arranged and / or configured such that the membrane assembly 16 has a substantially common acoustic center. The division of the membrane assembly 16 in three membrane segments A, B and C is indicated by the two dashed lines in the FIGS. 7 and 8 indicated. The design of the individual membrane segments A, B and C or their exact training / arrangement with the wave crests shown, wave troughs and flanks, but without illustrated traces and their "control" may be discussed in more detail below, in advance, the following may be performed :

The membrane segments A, B and C are arranged such that the emitted from the membrane segments A, B and C sound waves 24 are superimposed so that the total sound 24, as coming from an acoustic center appears. The acoustic center corresponds to a - in Fig. 7 indicated, vzw. punctiform - sound source, being emitted from this sound source, indicated by circular arcs sound waves.

A common acoustic center here means that the respective circular arc centers of the sound waves lie on the emission axis S and not laterally offset from the emission axis. As long as the circular arc centers are close enough to each other on the emission axis S, the sound appears as coming from a common acoustic center. This makes it possible to achieve a precise image of the sound image. In other words, it is possible for the circular arcs 24a to associate a geometrical first point-shaped sound source and the circular arcs 24b with a second geometrical point-shaped sound source, which on the one hand lie on the emission axis S and on the other hand are so close to each other that a common acoustic center is realized for the listener ,

The membrane segments A, B and C are arranged symmetrically to the emission axis S or to the radiation plane of the membrane arrangement 16. The membrane segment B is arranged in the middle between the preferably identically designed outer membrane segments A and B. The middle diaphragm segment B is designed to reproduce in particular a high-frequency range and the two outer diaphragm segments A and C only to reproduce a low-frequency range. The membrane segment B generates the wavefronts 24a of the high-frequency range and the two membrane segments A and C together generate the wavefronts 24b of the low-frequency range. In another embodiment, the low frequency range can also be represented by all membrane segments together and the high frequency range, for example, only by the middle membrane segment B.

The frequency spectrum to be represented by the membrane arrangement 16 can be, for example, from 700 Hz or from 1 kHz to, for example, 20 kHz, vzw. even up to 30KHz. If a membrane arrangement is used with a correspondingly large total membrane area, the frequency range to be transmitted can also extend to less than 1 kHz or less than 700 Hz. The frequency spectrum can be in a high frequency range, vzw. from 3000 Hz to over 20,000 Hz, and a low-frequency range, vzw. from below 1000 Hz to 3000 Hz or above. In another embodiment of the invention, the frequency spectrum can also be divided into more than two frequency ranges, with at least one membrane segment being provided for each frequency range can.

Each membrane segment of a membrane assembly or a membrane therefore forms a separate "oscillatory unit" with several of these membrane segments associated wave crests and wave troughs, each membrane segment vzw. a certain frequency range is assigned. Here, the membrane segments are then arranged and / or formed so that the acoustic center is common for different frequencies or for the different frequency ranges. Vzw. Therefore, the directivity of the membrane assembly and the membrane is independent of the frequency. Vzw. But now every membrane segment for a particular frequency range is provided, for example. For a high-frequency range or even for a low frequency range.

The subdivision of the membrane assembly 16 in the three membrane segments A, B and C also has the advantage that the omnidirectional behavior of the membrane assembly 16 is improved. The limit for an acceptable omnidirectional behavior is vzw. characterized in that the extension of the membrane segments A, B and C in one direction is less than half the wavelength of the frequency to be generated. This condition is for the low-frequency reproduction associated membrane segments A and C usually not critical. For the emission characteristics of the high frequencies, only the extent of the central membrane segment B is crucial. Since with increasing frequency to be radiated membrane expansion should be small, is vzw. the extent of the membrane segment B at least in the horizontal direction substantially less than half the wavelength of the upper limit frequency of the high frequency range. The subdivision of the membrane assembly 16 in its membrane segments A, B and C is here in a horizontal extension of the membrane assembly 16 is carried out (seen from the perspective of the towering erected membrane assembly 16).

To reproduce low frequencies, the membrane arrangement 16 preferably has a correspondingly large area, in particular the total area of the membrane segments A and C has been chosen to be sufficiently large. The deeper the frequency of the diaphragm assembly 16 to be transmitted is selected, the greater preferably to choose the total membrane area for the reproduction of the lowest frequency. With a suitable choice of dimensions results in a horizontal plane bundle-free playback over the entire desired frequency range.

How out Fig. 9 can be clearly seen, remains by the segmentation of the membrane assembly 16 only in the width (as horizontal) and not in height (vertical) bundling the high-frequency sound 24a, while the lower-frequency sound waves are radiated cone-shaped.

It should be noted that the considerations made here on three membrane segments A, B and C analogously apply to a larger number of membrane segments, in particular for the following embodiments, which will be described.

There are now several ways to divide a membrane assembly into several membrane segments. For example, the membrane segments - as already in the Fig. 7 to 9 shown - may be formed as portions of a single membrane. In this case, the subregions, that is to say the corresponding membrane segments, for example the membrane segments A, B and C, can be fixed in their marginal / border areas according to the invention by separately arranged webs, so that the membrane segments are "decoupled" from one another in terms of vibration. It is also conceivable that "buffer zones" are formed between the membrane segments, that is, for example, the corresponding air pocket 23, which forms exactly the border region between two membrane segments, just not provided with conductor tracks. It is also conceivable that corresponding "buffer zones" be realized or fixed by adhesive bags filled with air pockets. This depends on the particular application.

In the preferred embodiments, therefore, the membrane assembly 16 and 26 consists of a single membrane, for example. The membrane 16 a, wherein the single membrane 16 a in corresponding membrane segments, vzw. the membrane segments A, B, C is divided. Here, a membrane segment A, B and C is essentially defined by a certain number of wave crests and troughs, and in particular from Fig. 7 shown clearly. Here, each membrane segment A, B, C forms a substantially separate "oscillatory unit", wherein the membrane segments A, B and C vzw. by elements not shown here in the figures, in particular webs, strips, etc. are limited to the membrane segments A, B, C vzw. to decouple vibration from each other. Thus, for example, in the Fig. 7 provided at the boundary regions shown in dashed lines between the membrane segments A and B and the membrane segments B and C such webs / strips in the region of the wave crest shown here in the respective boundary region in order to realize the vibration control decoupling. This means that each membrane segment a certain number of wave crests and troughs and flank sides are assigned, the troughs, wave crests and flanks of a first membrane segment, eg. The membrane segment A, swing in a different way than the wave crests and troughs of another In the preferred exemplary embodiments illustrated here, the membrane arrangement 16 or the membrane 16a is arranged substantially in one plane between two pole plates 17 and 18.

Furthermore, several individual vzw. Diaphragm-shaped membranes are provided, which then form corresponding respective membrane segments and are combined, for example in one or more frames to form a unit as a "membrane order". This depends on the particular application.

In the Fig. 10, 11a and 11b a second embodiment of an AMT transducer 25 is shown. With regard to the structure of the sound transducer 25 - with the exception of the segmentation of the membrane assembly 26 - is on the above description of the Fig. 7 to 9 referred, since the basic structure with the pole plates 27 and 28 and with an air gap 29 corresponds to the above, first embodiment substantially.

As in Fig. 10 is clearly recognizable, in contrast to that in the Fig. 7 to 9 illustrated transducer 15, the membrane assembly 26 here now additionally also segmented in the vertical direction.

The membrane assembly 26 has a central membrane segment B and laterally of this membrane segment B two outer membrane segments A and C. In addition, above and below the membrane segment B and preferably also above and below the lateral membrane segments A and C, two membrane segments E and D are arranged. Both the outer, lateral membrane segments A and C and the outer membrane segments D and E are arranged symmetrically to the middle membrane segment B, so that the entire membrane assembly 26 has a common acoustic center on the emission axis S. This acoustic center is in this embodiment for the listener - as already above to the Fig. 7 to 9 explained - vzw. punctiform. While in Fig. 7 the division of the membrane 16a in the horizontal direction in three membrane segments A, B, C is shown, which are formed in the vertical direction, ie over the entire height, so shows Fig. 10 another division of a single membrane 26, wherein here in the middle region, the three membrane segments A, B, C and in each case in the upper and lower region - seen in the vertical direction - further membrane segments D and E are formed. The vibrational decoupling of the membrane segments A, B, C, D and E can be realized here again via corresponding elements, in particular webs / strips and / or separate frame, so the corresponding membrane segments A to D can be limited by means of such elements. This also depends on the particular application.

This in the Fig. 10 or 11a and 11b shown second embodiment of the transducer 25 can therefore be considered as a supplement to the first embodiment (the transducer 15) to the two additional membrane segments D and E.

These two membrane segments D and E give vzw. only the low frequency range again and thus behave in particular as the membrane segments A and C. The middle membrane segment B is vzw. again responsible for the reproduction of the treble range. By segmenting the membrane assembly 26 in the horizontal and now also in the vertical plane becomes one in both planes improved omnidirectional behavior is achieved, as is the case for the horizontal plane Fig. 11a and for the vertical plane Fig. 11b is apparent.

For the possible lower limit frequency of individual membrane segments the following:

Fig. 12 shows a detail view of a portion 30 of a membrane segment once in the initial state 31 and once in the deflected state 32, wherein the direction of movement of the membrane segment 30 in the deflected state 32 is indicated by the outward-pointing arrows. In the deflected state 32, the air pocket 33 is widened by twice the distance a. In the initial state 31, the unspecified wave crests and wave troughs with the radius R are curved. In the deflected state, the wave troughs with the radius r1 and the wave peaks with the radius r2 are curved.
In this deflected position 32, the radius r1 is smaller than the radius r2. The maximum deflection of a, ie "a _max " is vzw. now chosen so that the forces acting through the inherent stiffness of the membrane material spring forces in the radii r1 and r2 are approximately proportional to the deflection. The lower the frequency to be generated, the greater is vzw. the deflection of the membrane to produce a sufficient sound pressure. The lower limit frequency is vzw. selected by the proportionality condition of the spring forces occurring in relation to the deflection. The lower limit frequency is therefore also dependent on the specific material properties of the membrane segment 30.

For the possible upper limit frequency of individual membrane segments the following:

The FIGS. 13 and 14 show a detailed view of a membrane segment 34 in maximum compressed state 35 and the initial state 36. The air in the air pocket 37 is in Fig. 13 compressed (compressed air "VK"), which is to be represented by the black bar graphically, and is therefore pushed out of the air pocket 37, which is indicated by the lower arrow in Fig. 13 is indicated. The resulting pressure wave needs a certain time t to cover this distance s as a function of the distance s to be traversed in the air pocket. This time is due to the speed of sound and the Way determinable.

With progressive membrane movement occurring in Fig. 14 is indicated by the outward arrows, the flanks 38 and 39 generate a negative pressure Vu. With increasing frequency, a part of the compressed air, ie a part of Vk, the air pocket 37 and the fold not leave before this pressure wave is compensated by the resulting negative pressure Vu again, which is also shown schematically here by means of black bars. The strength of this effect is dependent on the frequency with which the air pocket 37 is expanded and compressed and the ratio of the radius to the edge length of the air pocket 37. The longer the path in the air pocket 33 or 37 - or the depth of the air pocket - in proportion is the radius of the wave crest or the wave trough, the lower is the upper limit frequency of the membrane segment 34. Vzw. Therefore, the depth of the air pockets - especially for the high frequency range - is tuned to the radius with respect to the upper cutoff frequency.

Fig. 15 shows a third embodiment of a sound transducer 38 with a membrane assembly 39. The membrane assembly 39 has three membrane segments a, b and c. The membrane segments a, b and c have substantially the same geometry, ie, size, convolution and expansion. The geometry of the membrane segments a, b and c is chosen in accordance with the above considerations so that the membrane segments a, b and c can transmit the entire desired frequency range.

Fig. 16 shows an electrical circuit diagram (equivalent circuit diagram) for the sound transducer 38. The resistors Ra, Rb and Rc represent the resistances of the conductor tracks on the respective membrane segments a, b and c. The resistances Ra, Rb and Rc represent the possibly complex alternating current resistance of the membrane segments a, b and c. The inductive component of the corresponding strip conductors can be small, which is why the complex alternating current resistance here can correspond essentially to ohmic resistances.

It can be clearly seen that the resistors Ra, Rb and Rc are connected in series.

At the contact terminals 40 and 41, an AC signal can be applied. To the resistor Ra, a capacitor Ca is connected in parallel, and to the resistor Rc, a capacitor Cc is connected in parallel. Due to the parallel connection of the capacitors Ca and Cc, the high-frequency component of the alternating current signal is conducted past the membrane segments a and c and is therefore reproduced only by the membrane segment b. By this wiring, the phase angle between current and voltage at the diaphragm segments a, b and c in the transition frequency between the high and the low frequency range is the same. This constant phase angle guarantees that no phase jumps occur between high and low frequency segments at the crossover frequency, which could be clearly perceived by the ear.

The bass frequency is vzw from the capacitors. not transmitted and flows through the electrically connected in series segments a, b and c. In this low frequency range is therefore vzw. the whole membrane arrangement is active and contributes to the impedance. The overall impedance of the circuit is frequency dependent. For low frequencies, the total impedance is essentially Ra + Rb + Rc. For equally sized membrane segments a, b and c, Ra = Rb = Rc, i. the total impedance in the low frequency range is equal to 3 * Rb. In the high-frequency range, the resistors Ra and Rc do not contribute, since they are bridged by the capacitors Ca and Cc. The total resistance in the high-frequency range therefore essentially corresponds only to Rb and thus amounts to only one third of the total impedance 3 * Rb in the low-frequency range.

The signal component, which is reproduced only via the membrane segment b, or the resistor Rb, therefore generates at the same amplitude voltage a threefold higher current through Rb and thus exerts a threefold higher force on the membrane segment b. As a result, a threefold higher diaphragm deflection is brought about in the linear region of the reproduction. This compensates for the fact that only the membrane segment b is provided for the high-frequency range, ie only one third of the total diaphragm area is used for high-frequency reproduction.

ein linearer Frequenzgang erzeugbar ist.For other ratios of the membrane segments a and b to c analogous considerations apply, as by the reciprocal ratio of membrane area F to impedance $$\left(\mathrm{Ra}+\mathrm{Rb}+\mathrm{rc}\right)/\mathrm{Rb}=\mathrm{Fb}/\left(\mathrm{fa}+\mathrm{Fb}+\mathrm{Fc}\right)$$

a linear frequency response can be generated.

Preferably, these transducers are operated with amplifiers, the amplifiers vzw. at the occurring, different impedances depending on the frequency spectrum to be transmitted work stable.

so dass ein linearer Frequenzgang erzeugbar ist. Fig. 17 shows an alternative circuit for the in Fig. 15 shown transducer 38. The represented by the resistors Ra and Rc membrane segments a and c are in this case connected in series with an unspecified woofer unit. At this woofer unit can be fed to the contact terminals 42 and 43, a low-frequency signal. The membrane segment b, or the resistor Rb, is formed separately from the woofer unit and can be contacted at separate terminals 44 and 45 with a further signal. This signal can either contain only high-frequency components or, in addition to high-frequency components, also low-frequency components. The different control of the woofer unit and of Rb can be done, for example, via an active or a passive crossover network. In this case, the ratio of membrane areas and ohmic resistance vzw. also inversely proportional: $$\left(\mathrm{Ra}+\mathrm{rc}\right)/\mathrm{Rb}=\mathrm{Fc}/\left(\mathrm{fa}+\mathrm{Fb}\right).$$

so that a linear frequency response can be generated.

Fig. 18a shows a fourth embodiment of a transducer 46 with a membrane assembly 47, wherein the membrane assembly 47 is divided into three membrane segments a, b and c. The membrane segments a and c are in turn vzw. constructed identical and in particular arranged symmetrically to the central membrane segment b. In this case, the middle diaphragm segment b only reproduces the high-frequency range and is adapted accordingly. The membrane segments a and c are adapted to reproduce only the low frequency range. The membrane segment b has a convolution with a lower air pocket depth, so that this membrane segment b has a very high, upper limit frequency can have (cf. FIGS. 13 and 14 and the corresponding description). The air pockets of the membrane segments a and c thus have a greater depth than the air pockets of the membrane segment b.

Furthermore, vzw. the height Hb of the air gap 48 in the region of the tweeter membrane segment b is smaller than the height Ha / c of the air gaps 49 in the region of the woofer membrane segments a and c. The air gap 49 is bounded by two pole plates 50 and 51. The air gap 48 is limited here, for example, on the one hand by the pole plate 51 and on the other hand by an additional pole plate element 52. Due to the smaller extent of the folding of the membrane segment b in the direction Hb, it is possible here to work with an air gap 48 reduced in relation to the height Ha / c. Preferably, the magnetic field Bb acting in the air gap 48 of the high-tone membrane segment b is stronger than the magnetic field Ba / c acting in the air gap 49 of the low-frequency membrane segments a and c. Due to the stronger magnetic field, higher edge deflections can be generated. As a result, a compact design of the central membrane segment b can be achieved while at the same time having sufficient sound pressure through the membrane segment b. The perpendicular to the diaphragm assembly 47 oriented magnetic fields Bb and Ba / c are indicated by arrows in the Fig. 18a indicated.

Fig. 18b shows a circuit for the in Fig. 18a shown transducer 46. The represented by the resistors Ra and Rc membrane segments a and c are in this case connected in series with an unspecified woofer unit. At this woofer unit can be fed to the contact terminals 53 and 54, a low-frequency signal. The membrane segment b or the resistor Rb is formed separately from the woofer unit and can be supplied at separate terminals 55 and 56 with a high frequency signal. The different activation of the woofer unit and of the membrane segment b or of the resistor Rb can take place, for example, via an active or a passive crossover.

Fig. 19 shows a fifth embodiment of a sound transducer 57 with a membrane assembly 58. The membrane assembly 58 is again in accordance with the preceding embodiments in three membrane segments a, divided b and c. The diaphragm segments a and c provided for low-frequency transmission are designed such that they have an upper cutoff frequency, this upper cutoff frequency simultaneously corresponding substantially to the lower cutoff frequency of the high tone range, wherein the high frequency range of the membrane segment b is transferable. Vzw. For this purpose, the membrane segments a and c have a corresponding depth T of the air pockets 59 and a corresponding radius R of the curvature of the undefined peaks and troughs of the air pockets 59. The tweeter membrane segment b has air pockets 60 with a smaller depth T 'and peaks and troughs with a smaller radius R'. Therefore, the air pockets of each membrane segment a, b, c depending on which frequency range is assigned to the respective membrane segment a, b, c different depths, vzw. have the depth T or T '. Vzw. In this case, the high-tone membrane segment b or the depth T "of the air pockets 60 is less than the depth T of the air pockets 59. The respective membrane segments a, b and c are therefore in the preferred case with different depths v / T / T" of the air pockets 59 or 60 formed. Here, the membrane segments a, b, c are formed and / or arranged so that the acoustic center is common for different frequencies or for the different frequency ranges. The geometry of the membrane segments a, b and c, in particular the respective air pockets 59 and 60, is selected so that on the one hand the desired cutoff frequency is transferable and on the other hand, the frequency range of the membrane segments a and c is trimmed so that no further filtering measures are required ,

The membrane geometry is selected by the membrane arrangement 58 so that the membrane segment b can only reproduce the high-frequency range which lies beyond the upper limit frequency of the membrane segments a and c.

In Fig. 20 a circuit for the membrane assembly 58 is shown, wherein the membrane segments a and c, and the corresponding resistors Ra and Rc are connected in series to a woofer unit and the high-tone membrane segment separately, for example, by an active cross-over, not shown can be controlled (see. example Fig. 18b ).

Fig. 21 shows a further circuit for the membrane assembly 58. Here, the membrane segments a, b and c are connected in series, wherein an inductive resistor L, the high-tone membrane segment b and the resistor Rb bridges. The inductive resistor L is small for low frequencies and large for high frequencies. Since the resistor Rb is in parallel with the inductive resistor Rb, the same voltage drops at both. For low frequencies, therefore, only a small amount of the signal on the membrane segment Rb drops off. For high frequencies, preferably the voltage drops substantially at the high-tone membrane segment b.

Fig. 22a shows a further sound transducer 61 with a membrane assembly 62. As in the in Fig. 18a The embodiment shown here, the height of the air gap in the region of the tweeter membrane segment b is smaller than the height of the air gaps in the region of the woofer membrane segments a and c. The air gap is partially bounded by two pole plates 50 and 51. The air gap is additionally narrowed by an unspecified pole plate in the region of the high-tone membrane segment. As a result, the extent of the folding of the membrane segment b - or the depth of the air pocket - in the region of the high-tone segment drops to allow a high upper cut-off frequency of this membrane segment b. The magnetic field acting in the air gap of the high-tone membrane segment b is preferably stronger than the magnetic field acting in the air gap of the low-frequency membrane segments a and c. Due to the stronger magnetic field, higher edge deflections can be generated.

Furthermore, in this embodiment, the geometry of the membrane segment b is selected so that the membrane segment b can also reproduce the lower limit frequency of the membrane segments a and c. In particular, the radius R of the wave crests and wave troughs in the membrane segment b is adjusted accordingly. Vzw. the membrane segments a, b and c have a convolution with the same radius R, even if the depth of the unspecified air pockets in the membrane segments a and c deviates from the depth of the air pockets of the membrane segment. As already stated, the lower limit frequency is determined by the radius of the wave crests and wave troughs. This makes it possible to dispense with a crossover completely. The membrane segments a, b and c are, as in Fig. 22b is shown, vzw. connected in series without bridging or filter links. In this embodiment, the signal or the current flows completely through all membrane segments a, b and c - or the resistors Ra, Rb and Rc. The bass range is represented by all membrane segments a, b and c. The electrical signal of the high-frequency range also flows through the resistors Ra, Rb and Rc, but is not reproduced due to the above-described relationships of the membrane segments a and c. Vzw. the high-frequency signal component is amplified compared to the low-frequency signal component. This can happen, for example, by electronic means, in particular with an equalizer, in particular before the overall signal is amplified. This amplification of the high-frequency signal component can be boosted / amplified, in particular, without a significant or audible phase shift occurring between the high-frequency signal component and the low-frequency signal component. On an active or passive crossover, which separates the signal components for the membrane segments a / c and b, can be dispensed with.

The in the Fig. 7 to 22nd substantially schematically illustrated acoustic transducers, which are in particular designed as AMT speakers, have corresponding membrane assemblies 16, 26, 47 and 58 and 62, which are formed in accordance with the above-described explanations, vzw. each having a single membrane. In the event that these membrane arrangements have a single membrane, the corresponding subregions, ie the corresponding membrane segments A, B, C, D, E or a, b and c vzw. according demarcated or divided by that at the edge areas or in the transition areas vzw. web elements not shown here can be arranged to separate the respective membrane segments from each vibration technology. Conceivable, however, are also formed in the corresponding transition areas "buffer zones", for example. By virtue of the fact that air pockets provided here just have no traces or these corresponding air pockets are possibly attached appropriately with adhesive and / or partially filled. This depends on the particular application.

Due to the different control possibilities of the individual membrane segments A, B, C or a, b, c, as described, exists vzw. a tweeter segment and vzw. a plurality of low tone segments arranged corresponding to one another to form a common acoustic center, particularly for the listener. In particular, the individual membrane segments can be correspondingly controlled differently with the aid of an electrical / electronic control unit, vzw. because the respective interconnects of a membrane segment are electrically driven differently than the respective interconnects of another membrane segment. Also by the different air pocket depth of the respective membrane segments associated air pockets, the assignment of the frequency ranges can be carried out or so controlled. It is also conceivable that the individual membrane segments are formed by a plurality, that is, by a plurality of individual membranes, which are arranged correspondingly in different frames. This means that the corresponding membrane arrangement does not have to consist of a single membrane, as in the preferred embodiments shown here in the figures, but the membrane arrangement can also be formed by a plurality of individual membranes, each individual membrane then forming a corresponding individual membrane segment, and these membrane segments are in turn designed and / or arranged such that - corresponding to the above statements - the entire membrane arrangement has a substantially common acoustic center. This also depends on the particular application.

Due to the arrangement of the membrane segments to each other and also due to the formation of the different air pockets, the corresponding disadvantages are avoided in the prior art and in particular realized AMT speakers with an optimal omnidirectional behavior.

LIST OF REFERENCE NUMBERS

1

diaphragm assembly

1a

membrane

2

conductor path

3

Wellenberg

4

trough

5

flanks

6

air pocket

6a

air pocket

6b

air pocket

6c

air pocket

6d

air pocket

6e

air pocket

6f

air pocket

6g

air pocket

7

pole plate

8th

pole plate

9

air gap

10a

frame part

10b

frame part

11a

side panel

11b

side panel

12

sound holes

12a

slots

13

sound waves

14

sound waves

15

transducer

16

diaphragm assembly

16a

membrane

17

pole plates

18

pole plates

19

air gap

20

Wellenberg

21

trough

22

flanks

23

air bags

24

sound waves

24a

wavefronts

24b

wavefronts

25

transducer

26

diaphragm assembly

27

pole plates

28

pole plates

29

air gap

30

subregion

31

initial state

32

deflection state

33

air pocket

34

subregion

35

maximum compressed state

36

initial state

37

air pocket

38

transducer

39

diaphragm assembly

40

contact terminals

41

contact terminals

42

contact terminals

43

contact terminals

44

contact terminals

45

contact terminals

46

transducer

47

diaphragm assembly

48

air gap

49

air gap

50

pole plates

51

pole plates

52

Polplattenelement

53

contact terminals

54

contact terminals

55

contact terminals

56

contact terminals

57

transducer

58

diaphragm assembly

59

air bags

60

air bags

61

transducer

62

diaphragm assembly

I

electricity

A, B, C, D, E

or a, b, c membrane segments

Vu

vacuum

vk

compressed air

Claims (12)

1. AMT loudspeaker having a diaphragm arrangement (16, 26, 39, 47, 62), wherein the diaphragm arrangement (16, 26, 39, 47, 62) has a single diaphragm (16a) of essentially meandrous design, wherein the diaphragm (16a) has, as a result of the meandrous design of the diaphragm (16a), air pockets (32, 59, 60) for producing sound, a plurality of wave peaks (20) and wave valleys (21) and also conductor tracks arranged on sides (22), wherein the frequency spectrum to be reproduced by the diaphragm (16a) is divided into a treble range and a bass range or into more than two frequency ranges and the diaphragm (16a) has a plurality of diaphragm segments (A, B, C; a, b, c) therefor, wherein each frequency range has at least one diaphragm segment (A, B, C; a, b, c) provided for it and the diaphragm segments (A, B, C; a, b, c) are arranged and/or designed such that the diaphragm (16a) has an essentially common acoustic centre, namely a central diaphragm segment (B; b) is designed for the reproduction of a treble range and a bass range and two outer diaphragm segments (A, C; a, c) are designed for the reproduction of a bass range, wherein an electrical circuit is provided and the diaphragm segments (A, B, C; a, b, c) are at least to some extent connected in series or the conductor tracks of the respective diaphragm segment (A, B, C; a, b, c) can be actuated in electrically different ways, characterized in that a treble component can be routed past the diaphragm segments (A, C) provided for bass transmission by means of a bypass element, wherein the individual diaphragm segments (A, B, C, a, b, c) are decoupled from one another in terms of oscillation, namely crosspiece-like elements are arranged on the bottom of the respective air pockets in the border regions between the diaphragm segments (A, B, C; a, b, c), so that each diaphragm segment (A, B, C; a, b, c) forms a separate oscillatable unit.
2. AMT loudspeaker according to Claim 1, characterized in that the diaphragm arrangement (16, 26, 39, 47, 62) has a radiation axis (S) and the diaphragm segments (A, B, C; a, b, c) are arranged symmetrically with respect to the radiation axis (S).
3. AMT loudspeaker according to one of the preceding claims, characterized in that the extent of the diaphragm segments (A, B, C) is essentially less than half the wavelength of the upper cut-off frequency of the frequency ranges.
4. AMT loudspeaker according to one of the preceding claims, characterized in that the surface area of the diaphragm segments (A, B, C) matches the lower transmittable cut-off frequency of the diaphragm arrangement (16, 26, 39, 47, 62).
5. AMT loudspeaker according to one of the preceding claims, characterized in that the depth of the air pockets is attuned particularly to the radius of the wave peak or wave valley of the air pocket.
6. AMT loudspeaker according to one of the preceding claims, characterized in that the depth (T') of the air pockets of the diaphragm segment (B) provided for treble transmission is less than the depth (T) of the air pockets of the diaphragm segments (A, C) provided for bass transmission.
7. AMT loudspeaker according to one of the preceding claims, characterized in that outer diaphragm segments (D, E) are arranged above and below the central diaphragm segment (B).
8. AMT loudspeaker according to one of the preceding claims, characterized in that the diaphragm segments (A, B, C, D, E) are in essentially rectangular or square form.
9. AMT loudspeaker according to one of the preceding claims, characterized in that the ratio of the diaphragm surface area of an individual diaphragm segment to the total diaphragm surface area is reciprocal in its behaviour with respect to the ratio of the impedance of the individual diaphragm segment to the total impedance of all diaphragm segments.
10. AMT loudspeaker according to one of the preceding claims, characterized in that to implement the oscillatory decoupling of the diaphragm segments (A, B, C) in the cross-over areas, "buffer zones" are implemented by virtue of air pockets having no conductor tracks at this point.
11. AMT loudspeaker according to one of the preceding claims, characterized in that the diaphragm segments (A, B, C) are arranged in an air gap between pole plates (50, 51).
12. AMT loudspeaker according to one of the preceding claims, characterized in that the diaphragm segment (B) intended for the treble reproduction is arranged in an air gap of lesser height than the diaphragm segments (A, C) for the bass reproduction.

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