EP1079664B1 - Electrodynamic driver - Google Patents

Abstract

The driver has a moving coil (8) on a tubular coil holder (8a), with a magnet system (4,5,6) arranged concentric to the coil. An adaptor (9) is provided for attaching the coil holder to the diaphragm (12). An elastic element (2,7) is arranged between the diaphragm and the magnet system. A cavity (10,11,15,17) is formed between the diaphragm and the magnet system. An element (7) made of air permeable material is provided for equalising the pressure of the cavity. A pressure equalising channel (24,16) may be provided from the cavity to the outside air.

Description

The invention relates to an electrodynamic driver for a membrane having a voice coil applied to a tubular coil carrier, a concentrically arranged with respect to the voice coil, axially movable magnet system, an adapter for securing the coil carrier to the membrane, an arranged between the membrane and magnet system elastic element, wherein forms at least one cavity between the membrane and the magnet system.

The publication US 5,909,015 describes a self-cooling speaker with a permanent magnet assembly having at least one air inlet. The publication US 5,426,707 refers to a speaker with a cooling element for generating an air flow for cooling the electrical conductors in the speaker. The publication DE 44 21 418 A1 relates to a centering diaphragm for loudspeakers, wherein the centering diaphragm formed of non-magnetizable material and means are provided which allow the exchange of air between the areas located above and below the centering diaphragm. The publication DE 29 19 884 A1 also describes electromechanical vibration transducers.

Plate loudspeakers consist essentially of a holder (frame), a membrane (plate) and a drive system. The drive system of the panel loudspeaker consists of one or more electromechanical transducers. At present, only piezoelectric drivers (PVDF films or piezo ceramics) or electrodynamic drivers (magnetic system / oscillating head) are used as transducers.

The oscillating head of the electrodynamic driver consists of the voice coil, the coil carrier, an elastic element and the adapter. As an adapter is any suitable for anchoring the bobbin on the plate suitable connection element designated. Such a generic driver is for example from the European patent EP 0 847 676 B1 known. However, the transmission quality of the drivers is still considered too low for some applications.

The object of the invention is to further improve an electrodynamic driver of the type mentioned.

The object is achieved by a driver according to claim 1. Embodiments and developments of the inventive concept are the subject of dependent claims.

In electrodynamic drivers for a membrane having a mounted on a tubular bobbin voice coil, a concentric with respect to the voice coil, axially movable magnet system, an adapter for securing the bobbin to the membrane and an arranged between the membrane and magnet system elastic element, usually form Cavities between membrane and magnet system. According to the invention, it has been found that the air trapped therein acts as an additional elastic element upon movement of the membrane, which itself is dependent on external influences (e.g., air pressure, temperature) and, in turn, correspondingly affects the transmission characteristics of the driver. The invention therefore provides means for pressure equalization of the at least one cavity.

For pressure equalization air-permeable elements (eg coarse-pored tissue, fleece) which is in contact with the outside air, and / or pressure equalization channels (eg bore, groove, notch) leading from the cavity to the outside air can be provided. In addition, at least one cavity can have a pressure compensation opening (eg windows, slots) to the outside air.

In the case of multiple cavities and means for pressure equalization between at least two cavities can be provided. These may be connected to each other again via air-permeable elements and / or pressure equalization channels and / or have a common pressure equalization opening.

The pressure equalization openings can be incorporated into the elastic element. As an elastic element, a circumferential bead can be provided, which has at least one pressure equalization opening and / or is permeable to air.

In addition, the magnet system and / or the adapter may also have at least one pressure compensation opening and / or a pressure equalization channel that is in contact with at least one cavity.

The above-explained pressure compensation openings serve on the one hand the dynamic and on the other hand the static pressure compensation. In addition, they provide cooling of the driver system.

Figur 1

eine bevorzugte erste Ausführungsform eines erfindungsgemäßen Treibers und

Figur 2

eine bevorzugte zweite Ausführungsform eines erfindungsgemäßen Treibers.

The invention will be explained in more detail with reference to the embodiments shown in the figures of the drawing, wherein like elements are provided with the same reference numerals. It shows:

FIG. 1

a preferred first embodiment of a driver according to the invention and

FIG. 2

a preferred second embodiment of a driver according to the invention.

At the in FIG. 1 shown electrodynamic driver 1 is a tubular coil support 8a, on which a coil 8 is wound, by means of a consisting of an adapter plate 9a and an adapter foot 9b, concentric, one-piece adapter 9 attached to a plate membrane 12. Opposite the plate diaphragm 12, in the axial direction of the coil carrier 8a with coil 8, a magnet system is arranged, which forms an air gap 18, in which the coil 8 and partly the coil carrier 8a dip. The magnet system consists of a ferromagnetic magnetic pot 4 which surrounds the coil 8 on its lateral surface and on the cross-sectional surface opposite the plate membrane 12, and of a permanent magnet 5 arranged in the interior of the magnet pot 4 and the coil support 8a in conjunction with a pole disk 6 On the lateral surface of the magnetic pot 4, a concentric housing 3 extending in the radial direction away from the magnet pot 4 and axially towards the plate membrane 12 is fastened, to which in turn the ends of two beads (a centering bead 7 and a load bead 2) are attached , The other end of the centering bead 7 is with the adapter 9 and the other end of the load bead. 2 is connected in the opposite direction with the plate membrane 12.

The load bead 2 has the task of fixing the magnet system (magnet pot 4, permanent magnet 5 and pole disc 6) to the plate diaphragm 12 (soft springy for axial movement, hard spring for radial and tilting movements). The load bead 2 could also extend further outward from the outer edge of the magnet system or further inwards. But it could also be omitted in a different type of holder. To avoid static tilting moments, the load thickness 2 attacks in the center of gravity. The centering bead 7, in turn, has the task of fixing the oscillating head (voice coil 8, coil carrier 8a and adapter 9) to the magnet system (soft springy for axial movement, hard-springing for radial and tilting movements). However, the centering bead 7 could also extend from the outer edge of the oscillating head further outwards or further inwards. With different types of holder, it could be completely eliminated.

In the described embodiment, the load bead 2 consists of a separate component. However, it may also be part of the housing 3 itself, if this consists of compound material in which the magnetic system receiving housing part formed hard and the Lastsickenteil for the purpose of cushioning made of softer material.

In such a structure, there are various cavities whose volumes increase and decrease accordingly during operation of the driver. The more or less tightly trapped in the cavities air is then compressed or expanded accordingly. This results in an additional spring action, which is particularly dependent on the volume and the tightness of the cavity. However, the properties of the additional spring are difficult to keep constant and vary from item to item and under different operating conditions. According to the invention therefore provided in the cavities of the embodiment for a pressure equalization, which ensures a rapid exchange of air in both directions, so that no spring action.

In the embodiment, one of the cavities - called in the further bead chamber 17 - by the plate diaphragm 12, the adapter 9, the centering bead 7, the housing 3 and the load bead 2 limited. Another cavity (housing chamber 11) is defined by the housing 3, the centering bead 7, the adapter 3, the voice coil 8 with coil holder 8 a and the air gap 18. Furthermore, a magnet chamber 10 called cavity by the magnet pot 4, the permanent magnet 5, the pole disc 6, the voice coil 8 is enclosed with coil support 8a and the air gap 18 and a pole chamber 13 said cavity by adapter 9, the coil holder 8a and the pole disc 6 set wherein in the embodiment, the axial height hp of the pole chamber 13 is advantageously less than the free height hm in the magnetic chamber 10. Another Cavity (adapter chamber 15) is finally formed by the adapter 9 in conjunction with the plate membrane 12.

For pressure equalization of the beading chamber 17, the load bead 2 was provided in the embodiment according to the invention with a perforation through the pressure equalization openings 19 can take place an exchange of air with the outside air, whereby the same pressure in the beading chamber 17 as in the outside air is achieved. From the beading chamber 17, a pressure equalization of the housing chamber 11 and the adapter chamber 15 takes place. For this purpose, the centering bead 7 made of air-permeable material, for example made of coarse-pored elastic fabric having a plurality of small pressure equalization openings 20. The adapter 9 has a bore which leads from the Sikkenkammer 17 to the adapter chamber 15 and serves as a pressure equalization opening 16 between these two chambers. In addition, a pressure compensation opening 14 is provided between the adapter chamber 15 and pole chamber 13, wherein the pole chamber 13 is also connected to the housing chamber 11 via a serving as a pressure equalization opening 21 bore in the coil holder 8a. Since the air gap 18 is usually too small an effective cross-section for pressure equalization, provided as a pressure equalization opening 24 bore in the magnet pot 4 is inserted such that it connects the magnetic chamber 10 with the outside air. Thus, two cavities are directly in connection with the outside air, while the other cavities indirectly at least via these two and optionally further cavities also with the Have outside air contact. This ensures that there is always external pressure in all cavities.

Such pressure compensation openings are particularly advantageous, even necessary, if ferrofluid is used in the air gap, which would prevent the pressure equalization.

Instead of the pressure equalization openings and cavities described, it is also possible to provide bores or other recesses in the housing, in the membrane or in the pole disk. These holes and recesses serve, as already mentioned, the cooling of the housing interior.

Opposite the in FIG. 1 embodiment shown is the embodiment according to FIG. 2 Modified to the effect that the housing 3, centering 7 and 2 load bead FIG. 1 omitted. In addition, the pole disk 6 in the embodiment according to FIG. 2 formed in cross-section T-shaped and is in contact with a combined centering and load bead 23, in which an adapter foot part 23a, an adapter head part 23c and an intermediate flexible adapter intermediate ring 23c are incorporated. The adapter with adapter foot part 23 a, adapter head part 23 c and adapter intermediate ring 23 c are used to attach the driver to the sound board 12th

Cavities form in this embodiment, in particular in the interior of the adapter (adapter chamber 15), between adapter, voice coil 8 and pole disc 6 (Polkammer 13) and between Polscheibe 6, permanent magnet 5 and magnetic pot 4 (magnetic chamber 10). By a pressure equalization port 14 adapter chamber 15 and pole chamber 13 are connected to each other, wherein the adapter chamber 15 is in communication via a pressure equalization opening at 16 with the outside air. The pressure equalization of the magnetic chamber 10 is carried out except the air gap 18 by means of a formed by a hole in the magnet pot pressure equalization port 24 Finally, could optionally - as in the embodiment according to FIG. 1 - In addition, a bore through the bobbin 8a are provided as a pressure equalization opening 21 (in FIG. 2 Not shown).

Claims (11)

1. An electrodynamic driver for a membrane (12) with a moving coil (8) mounted on a tubular coil carrier (8a), an axially movable magnet system (4, 5, 6) arranged concentrically with respect to the moving coil (8), an adapter (9) for connecting the coil carrier (8a) to the membrane (12), an elastic element (2, 7, 23b) arranged between the membrane (12) and magnet system (4, 5, 6), wherein at least one hollow space (10, 11, 15, 17) is defined between the membrane (12) and magnet system (4, 5, 6), characterised in that an element (7) of air permeable material is provided, which is in contact with the surrounding air, for pressure balancing the at least one hollow space (10, 11, 15, 17).
2. An electrodynamic driver as claimed in claim 1, characterised in that at least one pressure balancing passage (24, 26) is provided, which leads from the hollow space (10, 14) to the surrounding air.
3. An electrodynamic driver as claimed in claim 1 or 2, characterised in that at least one hollow space (17) has a pressure balancing opening (19) to the surrounding air.
4. An electrodynamic driver as claimed in one of claims 1 to 3, characterised in that a plurality of hollow spaces (10, 11, 15, 17) are defined and that means for pressure balancing (16, 18, 20, 21) are provided between at least two hollow spaces (10, 11, 15, 17).
5. An electrodynamic driver as claimed in claim 4, characterised in that at least two hollow spaces (11, 17) are connected together via an air permeable element (7).
6. An electrodynamic driver as claimed in claim 4 or 5, characterised in that at least one pressure balancing passage (16) connects at least two hollow spaces (15, 17).
7. An electrodynamic driver as claimed in one of claims 4 to 6, characterised in that at least two hollow spaces (13, 15) have a common pressure balancing opening (14).
8. An electrodynamic driver as claimed in one of the preceding claims, characterised in that the elastic element (2, 7) has at least one pressure balancing opening (19) and/or is air permeable (20).
9. An electrodynamic driver as claimed in claim 8, characterised in that a peripheral pleat (2, 7) is provided as the elastic element which has at least one pressure balancing opening (19) and/or is air permeable (20).
10. An electrodynamic driver as claimed in one of the preceding claims, characterised in that the magnet system (4, 5, 6) has at least one pressure balancing opening (18) and/or at least one pressure balancing passage (10).
11. An electrodynamic driver as claimed in one of the preceding claims, characterised in that the adapter (9) has at least one pressure balancing opening (14) and/or at least one pressure balancing passage (16).

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