EP0804048A2 - Loudspeaker - Google Patents

Abstract

The loudspeaker (10) has at least one radially magnetised permanent magnet (12), supported by a mounting made of a paramagnetic or diamagnetic material, which may be provided in one piece with the loudspeaker cone which is made of a metal or metal alloy. The permanent magnet can be provided by a ring positioned between 2 identical loudspeaker membranes (13,13'), with a common oscillation coil body (15) at the centre of the permanent magnet.

Description

Technical field

The invention is concerned with the formation of loudspeakers, in particular with the formation of drive systems for such loudspeakers and with the mutual association of such loudspeakers.

State of the art

According to the prior art, it is known to design drive systems for loudspeakers in such a way that a permanent magnet is connected to so-called yoke or yoke parts, an annular gap being left on the yoke parts, in which the voice coil connected to the loudspeaker diaphragm is subsequently immersed. Such an arrangement, which has a permanent magnet magnetized axially to the longitudinal axis of the magnet system, is shown for example in DE-A-4113017. Magnet systems with two permanent magnets show the documents DE-A-4234069 and DE-A-4225156.

In addition, magnet systems are known which have permanent magnets magnetized radially to the longitudinal axis of the magnet system. These permanent magnets are either made in one piece or consist of a series of permanent magnet segments. Such arrangements are known for example from WO 93/03586. In these arrangements too, yoke parts are present which guide the magnetic flux provided by the permanent magnets, so that sufficient induction is made available to the annular gap.

A disadvantage of these systems and loudspeakers is the complex production, the high weight and the large volume. The invention is therefore based on the object of creating a magnet system which avoids the disadvantages according to the prior art.

Presentation of the invention

This object is achieved with the features of claim 1. Advantageous further developments of the invention can be found in claims 2-7.

The basic idea of the present invention is to use the leakage flux emitted by a radially magnetized permanent magnet to drive a voice coil. This makes it possible to form the receiving parts for the permanent magnet from a para or diamagnetic material. This has the consequence that a considerable reduction in space and weight is achieved, since the geometrical specifications for the yoke parts, which according to the prior art have to be observed for guiding the magnetic flux within these parts, are irrelevant according to the invention. The manufacture of magnet systems is also greatly simplified according to the invention, since work steps which are necessary to connect the otherwise customary yoke parts according to the prior art are omitted. Rather, the receiving part according to the invention only forms the rear end of the loudspeaker or a support structure for the permanent magnet and the other components of the loudspeaker.

Since a cone loudspeaker usually has a loudspeaker basket which is connected to the magnet system, since the receiving part according to the invention has no function with regard to the magnetic flux and should not have with regard to the use of the leakage flux, one-piece units made of the receiving part and Manufacture loudspeaker basket very inexpensively.

Plastics, metals and metal alloys are suitable materials for forming receiving parts or units made of receiving part and speaker basket. It is particularly advantageous to use metal to form receiving parts in the above sense, since these materials simultaneously ensure good heat dissipation in the area of the drive system of the loudspeaker.

A particularly effective use of the leakage flux emitted by the permanent magnet is given if the magnet system is designed according to claim 5. In this case, the leakage flux emitted by the permanent magnet is used by both coils to drive a membrane.

To increase the leakage flux required for the diaphragm drive, two or more permanent magnets with mutual axial spacing in the direction of the longitudinal axis of the magnet system can also be arranged. With such a design, each of these permanent magnets can be surrounded by a voice coil on its inner shell side and / or outer shell side. If additional voice coils are to be used to drive a membrane, for example, it is necessary to rigidly connect these voice coils to one another. The magnet system according to the invention can also be modified so that, for example, all of them Coils arranged on an inner lateral surface of the permanent magnet can be used to drive a membrane and all coils arranged on the other lateral surface can be used to drive another membrane.

The design of the loudspeaker according to claim 7 is very particularly advantageous. If the respective voice coil former is approximately tubular and the first end of this voice coil former is connected to a first membrane and the second end of this voice coil former is connected to a second membrane and the two membranes, their suspensions, etc. designed completely identical, such an arrangement can be used as a dipole emitter, for example to generate a diffuse sound field for Dolby Surround playback. Diffuse sound fields of this type are generated according to the prior art by using two completely identical loudspeakers with inverse polarity reversed polarity with separate volumes. With such arrangements, however, the desired effects can only be achieved if the two loudspeakers have a reproduction frequency response that is identical up to 1-2 dB. If these conditions are not met, the respective sound event is perceived as coming from the front or as coming from behind. As can be easily seen, the identity in the playback frequency response can only be ensured by considerable effort in production. However, if the arrangement for generating a diffuse sound field is designed according to claim 7, deviations, which are caused, for example, by production-related diaphragm differences or unavoidable manufacturing differences when assembling the loudspeakers, are compensated or averaged in that the manufacturing-related deviations of all diaphragms etc. by a mechanical Coupling of both membranes are effective in every operating state.

Brief presentation of the figures

Figur 1

einen Schnitt durch einen Lautsprecher;

Figur 2

eine perspektivische Darstellung eines Dauermagneten;

Figur 3

eine weitere Darstellung gemäß Figur 1;

Figur 4

eine weitere Darstellung gemäß Figur 1;

Figur 5

einen Schnitt durch eine Dauermagnetanordnung; und

Figur 6

eine weitere Darstellung gemäß Figur 1.

Show it:

Figure 1

a section through a speaker;

Figure 2

a perspective view of a permanent magnet;

Figure 3

a further representation according to Figure 1;

Figure 4

a further representation according to Figure 1;

Figure 5

a section through a permanent magnet arrangement; and

Figure 6

another representation according to FIG. 1.

Ways of Carrying Out the Invention

The invention will now be explained in more detail with reference to the figures.

A loudspeaker (10) is shown in section in FIG. This loudspeaker (10) is essentially formed by a receiving part (11), a permanent magnet (12) and a membrane (13). In the present exemplary embodiment, the receiving part (11) is formed from a loudspeaker basket (11a) and a mandrel (11b). Polycarbonate was used as the material for the parts (11a and 11b). This is not restricted to this material. Rather, in another example (not shown), other plastics, such as A B S, or metals, for example aluminum, can be used as materials, provided that these materials have para- or diamagnetic properties. It is essential that at least the dome (11b), that is to say the part which is physically connected directly to the permanent magnet (12), is formed from a para- or diamagnetic material in order to prevent the permanent magnet (12) from directly contacting it. not weaken outgoing field. Combinations are also not excluded from the invention, which have a dome (11b) made of a paramagnetic or diamagnetic material and a loudspeaker basket (11a) made of a ferro-magnetic material.

As is easy to see, combinations of the parts (11a, 11b) made of paramagnetic or diamagnetic materials are the most advantageous design. Apart from the neutral effect of such combinations on the Sreufeld of the permanent magnet (12), such combinations are also very inexpensive to manufacture . The latter applies in particular if the receiving part (11) is formed in one piece. Such a one-piece design of a receiving part (11) is shown in FIG. 4.

The mandrel (11b) shown in FIG. 1 is circular, the end of the mandrel (11b) facing away from the basket (11a) having a smaller diameter than the end near the basket (11a). This design of the mandrel (11b) serves for the positive reception of the annular permanent magnet (12). For the sake of completeness, it should be pointed out that the mandrel (11b) does not necessarily have to completely or partially fill the inside diameter of the permanent magnet (12). An embodiment in which the mandrel (11b) does not completely fill the inside diameter of the permanent magnet (12) is shown in FIG. 4.

A conical membrane (13) is inserted into the basket (11a) shown in FIG. 1. The upper end of the membrane (13) is connected to the basket (11a) by means of a bead (14). The lower end of the membrane (13) has a voice coil support (15) which projects into the space encased by the membrane (13). The visual voice coil (16) is wound around the outer jacket of the voice coil former (15). Although this arrangement of the voice coil (16) on the outer jacket of the voice coil former (15) is advantageous from the manufacturing point of view, it may be necessary to better use the leakage flux to place the voice coil (16) on the inner jacket of the voice coil former (16) (the latter is shown in Fig 1 not shown).

There is a centering membrane (17) which is connected to the basket (11a) and the membrane (13) and which holds the voice coil (16) centrally to the longitudinal axis of the magnet system or the loudspeaker (10).

In addition, the mandrel (11b), the permanent magnet (12) and the voice coil (16) can be covered by a dust protection cap (18). In conventional loudspeakers (10), this dust protection cap (18) has the task of protecting the narrow annular gap from particle accumulations. This task also has the dust protection cap (18) used in the system according to the invention, although in the systems according to the invention which use the leakage flux, the distances between the voice coil (16) and the permanent magnet (12) are not so critical, so that if the Dust protection cap is not available, the accumulating particles are of minor importance.

As already indicated several times, the current-carrying voice coil (16) is driven in the stray field, which is generated by a radially magnetized permanent magnet (12). Therefore, in the exemplary embodiment according to FIG. 1, the north pole (N) lies on the outer lateral surface (19) and the south pole (S) lies on the inner lateral surface (20) of the permanent magnet (12).

As can be easily seen, the induction of radially magnetized permanent magnets (12) along the lateral surfaces 19/20 is constant, so that the voice coil (16) moves over its entire deflection path in a homogeneous magnetic field, which ultimately leads to very linear operation of the loudspeaker ( 10) leads.

The formation of permanent magnets (12) is not limited to the one-piece circular ring shape. 2 shows a permanent magnet (12), which is octagonal and consists of a series of permanent magnet segments (12a-h). Each of these segments (12a-h) is also radially magnetized as indicated on the segment (12a). The use of permanent magnets (12) in segment construction has the advantage that plate material can be used which can be magnetized more easily than permanent magnets (12) of circular design. The octagon shape of the permanent magnet (12) shown in FIG. 2 is only an example.

In another exemplary embodiment (not shown), the permanent magnet (12) can also be formed in a cuboid shape by the stringing together of only 4 segments.

3 shows a loudspeaker (10) which, in contrast to the design according to FIG. 1, has two voice coil carriers (15 and 15 '). These two voice coil carriers (15, 15 ') are connected at a mutual distance by means of an annular disc (21). In addition, each of the two voice coil carriers (15, 15 ') is provided with a voice coil (16, 16').

At its end facing away from the basket (11a), the mandrel (11b) is provided with a disk (22) which is likewise formed from a para- or diamagnetic material. The underside (23) of the disc (22) is connected to a radially magnetized permanent magnet (12) in the form of a circular ring. For the sake of completeness, it should be pointed out that the disk (22) can also be formed from a ferro-magnetic material, although such a selection of materials leads to somewhat poorer efficiency.

Since the inner diameter of the annular permanent magnet (12) is larger than the outer diameter of the mandrel (11b) and the two parts are constructed coaxially to one another, an "air gap" (24) is formed. The voice coil support (15) connected to the coil (16) is immersed in this "air gap" (24), while the voice coil (16 ') arranged on the voice coil support (15') the outer circumferential surface (19) of the permanent magnet (12) at a distance edged.

Since the two coils (16, 16 ') have the same winding direction and thus the direction of current flow in both coils (16, 16') is the same, in contrast to the configuration according to FIG. 1, the stray flux becomes considerably better for the configuration according to FIG Drive of the membrane (13) used. The latter conditions can also be achieved in the case of coils (16, 16 ') with opposite winding directions if the two coils (16, 16') are reversed in polarity to one another with an audio signal source (not shown).

For the sake of completeness, it should be pointed out that in the production of loudspeakers (10), for example shown in FIGS. 1 and 3, the devices which are also used for producing arrangements according to DE-A-4113017 can be used without major changes. In particular, in the arrangements according to the invention, the centering sleeves usually used for aligning and fastening the membrane (13) in the basket (11a), which are used to produce loudspeakers (10) between the pole core {mandrel (11b) and permanent magnet (12)} and the Voice coil former (15) are used.

3 with the two voice coils (16, 16 ') is not limited to the drive of only one membrane (13). Rather, the leakage flux of the radially magnetized permanent magnet (12) can also be used to drive different membranes (13, 13 '). Such relationships are shown in FIG. 4. In contrast to the representation according to FIG. 1, the permanent magnet ring (12) is placed on the mandrel (11b). Between the inner circumferential surface (20) of the radially magnetized permanent magnet ring (12) and the mandrel (11b) there is an "air gap" (24) into which a voice coil former (15 ') which is wound with a voice coil (16') is immersed. The upper end of the voice coil former (15 ') is provided with a dome-shaped membrane (13'). The outer edge of the dome-shaped membrane (13 ') is connected to the upper end of the permanent magnet (12).

If a voice signal from an audio signal source is applied to this voice coil (16 '), the membrane (13') can be used, for example, to emit high-frequency audio signals, while the membrane (13) serves to emit, for example, medium-frequency audio signals. In order to ensure that the partial tone frequencies emitted by the two membranes (13, 13 ') are in phase, both voice coils (16, 16') in this exemplary embodiment should be reversed in polarity with the audio signal source if both coils (16, 16 ') are made, for example, from manufacturing technology Have the same sense of winding.

FIG. 5 shows a mandrel-permanent magnet combination modified compared to FIG. 1. Two permanent magnets (12, 12 ') with mutual axial spacing are provided on the mandrel (11b). Each of these permanent magnets (12, 12 ') is magnetized radially, the same poles of the two permanent magnets (12, 12') pointing in the same direction. A voice coil support (16) is arranged next to the outer lateral surfaces (19) of the two permanent magnets (12, 12 '), to which two voice coils (16, 16') are also fixed at a mutual axial distance.

Such an arrangement should be chosen if the leakage flux of only one permanent magnet (12) alone is not sufficient to drive a membrane (13). If the two coils (16, 16 ') are to be used to drive only one membrane (13), the direction of current flow in both voice coils (16, 16') must be in the same direction.

The double-dotted dashed lines that intersect the voice coil support (15) indicate that the arrangement shown in FIG. 5 can also be used to drive different membranes (13) if the two voice coils (16, 16 ') are not on a common voice coil support ( 15) are arranged, but have independent voice coil carriers (15 '').

It is also not necessary that the mandrel (11b) according to FIG. 5 completely fills the inner diameter of the two permanent magnets (12, 12 '). Rather, the mandrel (11b) shown in FIG. 5 can also be modified in accordance with the embodiments shown in FIGS. 3 and 4.

For the sake of completeness, it should be mentioned that a mandrel-permanent magnet combination shown in connection with FIGS. 1 and 5 can be formed very advantageously by inserting the permanent magnet (s) (12, 12 ') into an injection mold so that the permanent magnets are connected (12, 12 ') can take place simultaneously with the formation of the mandrel (11b) or the receptacle (11) consisting of mandrel (11b) and basket (11a).

6 shows a dipole radiator (10 ') which shows a loudspeaker (10'') to the right and left of the double-dotted chain line.
Each of these loudspeakers (10 '') corresponds essentially to a loudspeaker shown in DE-A-4113017 (Fig. 1). Deviating from this, however, the magnet system is formed in FIG. 6. This is characterized in that it is formed by a radially magnetized permanent magnet (12). Since the first end (25) of the voice coil former (15) is connected to a membrane (13) and the second end (25 ') of the voice coil former (15) is connected to another membrane (13'). If a voice signal is now applied to the voice coil (16) connected to the voice coil support (15), the voice coil (16) moves and with it, via the voice coil support (15), each of the two membranes (13, 13 ') in the direction of the arrow. This means that air compression takes place on the membrane (13 '), while air dilution results on the membrane (13). However, since both membranes (13, 13 ') are coupled via the common voice coil support (15), the resistances present on the membrane (13') and affecting the free stroke of this membrane (13 ') also affect the stroke of the membrane (13), so that this is identical to the membrane (13 ') Receives lifting behavior. The result of this was that both membranes (13, 13 ') emit identical reproduction frequencies, which is of considerable importance for generating a diffuse sound field.

Finally, it should be pointed out that in another embodiment (not shown) in an arrangement according to FIG. 6, the permanent magnet rings (12, 12 ') shown in FIG. 5 can also be used. 6 can be modified so that, according to FIG. 4, the two diaphragms (13, 13 ') shown in FIG. 6, each of two with a lateral distance to the inner and outer lateral surface (19, 20) of the permanent magnet ( 12) arranged voice coils (16, 16 ') are driven.

Claims (8)

speaker with a magnet system which comprises at least one permanent magnet (12) which is magnetized transverse to the longitudinal axis of the magnet system, and with receiving parts (11) which carry or are connected to the permanent magnet (s) (12),
characterized by that the receiving parts (11) are formed exclusively from a material which has para- or diamagnetic properties. A loudspeaker according to claim 1,
characterized by that at least one speaker basket (11a) is present and that the respective receiving parts (11b) and the speaker basket (11a) are integrally formed. A loudspeaker according to claim 1 or claim 2,
characterized by that the receiving parts (11a, 11b) or the one-piece design of receiving parts (11b) and speaker basket (11a) are formed from metal or a metal alloy. Loudspeaker according to one of claims 1 to 3,
characterized by that the respective permanent magnet (12) is integrally formed as a circular ring or consists of a plurality of side-by-side permanent magnet segments (12a-h) which form a hollow profile in the connected state, and that a first voice coil (16) is present, which is arranged at a radial distance from one of the two lateral surfaces (19, 20) of the permanent magnet (12). A loudspeaker according to claim 4,
characterized by that a further voice coil (16 ') is present, which is arranged at a radial distance from the other lateral surface of the permanent magnet (12). A loudspeaker according to claim 4 or claim 5,
characterized by that in addition to the respective permanent magnet (12) there is a further permanent magnet (12 '), that the two permanent magnets (12, 12 ') are arranged at a mutual axial distance from one another with respect to the longitudinal axis of the magnet system and that the voice coils (16, 16 ') arranged radially to the respective lateral surface (19, 20) of the two permanent magnets (12, 12') are rigidly connected to one another. Loudspeaker according to one of claims 2-6,
characterized by that each voice coil (16, 16 ') is arranged on a voice coil former (15, 15'), although the voice coil former (15) for the two voice coils (16, 16 ') specified in claim 6 is a common voice coil former (15), that each voice coil former (15, 15 ') has a first end (25) and a second end (25') and that at least the first end (25) is connected to a membrane (13, 13 '). A loudspeaker according to claim 7,
characterized by that the first end (25) is connected to a first membrane (13) and the second end (25 ') to a second membrane (13') and that both membranes (13, 13 ') are identical.

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