DE1910970A1 - Electroacoustic converter - Google Patents

Description

191097Q

Patent attorney
DIpL-In?.? .. Beetz IL
Dipl.-Irr. · '· Mprecht

Munich 22, Stolnsdorfsir. 10

81-14.341P (14.342H) 4.3.I969

HISACHI, LED., Tokyo (Japan)

Electroacoustic converter

The invention relates to an electroacoustic transducer, in particular with an edge that can follow the movement of the membrane in the axial direction of the voice coil so that it expands and contracts in the circumferential direction of the membrane ο

The rim that holds the outer perimeter of a diaphragm in an electroacoustic transducer such as a loudspeaker, has a great influence on the bass reproduction and the distortion characteristics of the loudspeaker. As is well known the rim is generally used in two forms; H. as a fixed edge that forms the outer peripheral portion 41 of a membrane 40 (shown in FIG. 1), and as a free edge made of a material 42 such as soft leather, cotton fabric or Moltoprene (trademarks for polyurethane foam sold by Farbenfabriken Bayer AG toff), which carries a membrane 40 made of a different material. Fig. 1 and 2 show longitudinal sections

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by known dynamic loudspeakers that have a membrane 40, an edge 4i or 42, an attenuator 43, a voice coil 44, a permanent magnet 45, a pole yoke 46, a pole piece 47 and a basket 48 have.

The edge supporting the membrane should essentially have the following desirable properties »

a) The edge should have a sufficiently large reciprocal stiffness with respect to the axial movement of the membrane demonstrate.

b) The edge should have sufficient rigidity against the lateral movement of the membrane.

c) The edge should have good linearity in the case of oscillations of large amplitude.

d) The surface of the edge should be essentially free of distortions that lead to partial vibrations being able to lead. Furthermore, the edge should not generate any resonance.

e) The edge should have a small weight so as not to impair the free movement of the membrane »

The operation of the rim in the prior art loudspeakers illustrated in FIGS. 1 and 2 will now be described to check that the edge meets the various requirements outlined above. The edge should does not move in a direction perpendicular to the axis of the voice coil in the speaker and should have accurate piston movement run in the axial direction of the voice coil. In fact, however, the membrane has a complicated movement off when an AC input signal is fed to the speakers shown in Figs.

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When the membrane is in a direction · perpendicular to the axis the voice coil is moved is the ability of a wavy edge, e.g. B. to prevent the above movement of the diaphragm, rather small, so that the edge tends to follow the above movement of the diaphragm. Both in Fig. 1 and The edges shown in Figure 2 are of such a shape that they are very flexible to allow the diaphragm to move in the perpendicular direction to follow the axis of the voice coil.

Therefore, the voice coil is easily displaced, which hinders satisfactory operation of the speaker is. Furthermore, any unusual movement of the rim causes an undesirable mountain-valley effect (indentation) in the Reproduction of the loudspeaker as the edge takes up a considerable part of the radiating surface of the loudspeaker from the front of the speaker, occupies the Edges of the known speakers shown in Figs. 1 and 2 expand and contract so that a Kind of partial vibrations arise when the diaphragm not only is moved in the axial direction of the voice coil, but also in the direction perpendicular to the axis of the voice coil. There the vibration of the edge has a component which has a phase opposite to the vibration of the membrane, if a valley occurs in the reproduction, which has already been pointed out above. Furthermore, the known edge leads to a Resonance with the opposite of the vibration phase of the membrane Phase at a certain frequency, and as a result of such resonance, a valley occurs in the reproduction on.

Therefore, the known edge of diaphragms has several disadvantages that make it suitable for use in an electroacoustic Make transducers unsuitable by not having sufficient rigidity to allow the diaphragm to move in Direction perpendicular to the axis of the Schwingspu ^ e resistance, due to its flexibility in this

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Direction, and tends to a partial oscillation and resonance, although it has a considerably large reciprocal rigidity with respect to the movement of the diaphragm in the axial direction of the. Voice coil shows. Various efforts have already been made to overcome these difficulties. which includes changing the shape of the rim and pouring resin into the rim itself. However, it is by none these measures succeeded in producing an edge that meets the requirements specified above.

The rim according to the invention is characterized in that it has a V-shaped cross-section and a number of Has folds that are easily expandable and contractible in the circumferential direction of the membrane, making it so close is that it can follow the movement of the diaphragm in the axial direction of the voice coil, but sufficient rigidity has to resist movement of the diaphragm in its radial direction.

It is therefore the object of the invention to provide an electroacoustic transducer which has a good bass reproduction shows and can work with little sound distortion. Furthermore, the invention is intended to be an electromagnetic Transducers are specified with an edge that does not lead to an undesired resonance and a strong movement of the associated membrane · Finally, the invention is intended to indicate an edge which is highly reciprocal Rigidity with respect to the movement of the membrane in the axial direction of the electroacoustic transducer and sufficient Rigidity against the movement of the diaphragm in the direction perpendicular to the axis of the electroacoustic transducer has ο

The invention is to be explained in more detail with reference to the drawing «It shows

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Figures 1 and 2 are sectional views of known electroacoustic Converters that have already been described above {

Fig. 3 is a longitudinal section through the electroacoustic Converter according to the invention;

FIG. K shows a plan view of the edge of the electroacoustic transducer shown in FIG. 3

FIG. 5 is an enlarged perspective view of the part of the rim depicted in FIG. K; and

Fig. 6 is an enlarged sectional view taken along the line AA 'in Fig. K.

Fig. 3 shows a loudspeaker according to the invention in longitudinal section. A permanent magnet 1 is located in a central opening of a pole yoke 2; a pole disc 3 is mounted on the magnet 1 and a disc k made of Iall-absorbing material is mounted on the pole disc 3. A voice coil body 5 carries a voice coil 7 around it and is arranged in a space 6 between the pole yoke 2 and the pole disc 3. A frustoconical diaphragm 8 is connected to the voice coil bobbin 5 and carried by an annular rim 9. There is also a center cap 10, a basket 11 and a damping element 12 »

The diaphragm 8 surrounding and supporting edge 9 is shown in FIG · k displayed in the plan view. The edge 9 shown in Fig. K has a V-cross-section, the center being depressed to form the bottom of a V, as can be seen from Fig. 6, and is formed by 120 folds and 480 surfaces. The structure of the edge 9 will be described in more detail with reference to FIGS. 5 and 6. Fig. 5 is an enlarged per-

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Perspective view of part of the edge shown in FIG. 4, while FIG. 6 shows an enlarged sectional view along the line AA ¹ in FIG.

Circumferential folds 13 and 13 ', which are arranged continuously substantially in the middle of the edge 9, run in the circumferential direction of the membrane 8 in the form of a zigzag line. The Umfangsfalze 'extend in this direction in a zigzag shape having a certain length between their points of intersection D ^1, D and D ¹ O pads 14 and 14' 13 and 13 extend from the Umfangsfalzen 13 in opposite directions to the top with a width equal to the length of the line DD 'is ".Ähnlich extending surfaces 15 and 15' of the peripheral fold 13 'in opposite directions to the top with a width which is equal to the length of the line DD ^M. The surfaces 14, 14 », 15 and 15« mutually » End of the surfaces 14, 14 * or 15, 15 * formed. The folds 16 and 16 * form intersections C, C * and C ", while the folds 17 and 17 ^{1 form} intersections E, E« and E ^w »radial folds 18 and 19 _S which are arranged in the radial direction of the membrane 8, connect the Intersections C, D and E. Similarly, radial folds 20 and 21 connect the points of intersection C ¹ , D * and E ', while radial folds 22 and 23 connect the points of intersection C ",. Connect D "and E". Due to the presence of the circumferential folds 13 »13 '} 16, 16'j 17, 17' and the radial folds 18-23, the edge 9 can easily expand and contract in the circumferential direction of the membrane 8. In the radial direction of the diaphragm 8, the circumferential folds 13, 13 »} 16, 16« j 17, 17 »are only bent when a force is exerted on the diaphragm 8 to move it in this direction, while the remaining parts of the edge 9 in the radial direction of the membrane 8 due to the interaction of the radial folds 18-23 not

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can be bent, which oppose the force resistance. A sequence of these folds and surfaces forms the ring-shaped one Edge according to the invention

According to FIG. 6, the edge 9 is glued to the membrane 8 at a section a and to the basket 11 at a section b. In Fig. 6 the radial folds 18 and 19 of Fig. 5 are shown by hatched sections Zk and Zk ^x , while the radial folds 20 and 21 are shown by lines and 25 ', points c, c'j d, d ·} e, e ¹ in FIG. 6 correspond to the intersection points C, C ¹ | D, D ¹ j E, E ¹ in Fig. 5. To produce such an edge, the edge material, which can be a composite of synthetic fibers, is pressed between a male and a female mold which have convex and concave curvatures corresponding to the shape of the folds .

Various modes of operation of the rim shown in Figures k -6 in accordance with the invention will now be described in more detail.

6 shows part of the edge in enlarged cross-section, with single-dotted curves 26, 26j, 27, 27s, 28, 28; 29, 29 denote different positions of the radial folds Zk ₁ Zh , which are variable depending on the movement of the membrane 8, while a double-dotted curve 30 represents the path of the intersection point d between the radial folds Zk and Zk ^% . A triple-dotted curve 31 indicates the trajectory of point c of the edge.

It will first be described how the edge follows the movement of the membrane when the membrane 8 is vertical moved upwards from its rest position in FIG. 6. When the membrane 8 moves upwards, points ο follow and d of the edge 9 of this movement on curves 31 and in arrow directions F or G. That is, the point d moves

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to a point Q on the curve 30 as the point c moves to a point P on the curve 31 so that the folds 24, Zk move into the layers 26, Z6 . When the membrane 8 moves further upwards, the points c and d move to the corresponding points R and S, so that the folds 2k, Zk move into the layers 27 »27, which are aligned on the same straight line Maintain a certain angle between the folds Zk and Zk when the movement of the membrane 8 is small, and this angle is gradually increased as the movement of the membrane 8 increases, until finally the folds Zk ₁ Zk take their positions 27, 27, in which they cursed on the same straight line. The edge 9 follows the upward movement of the membrane 8 in the manner described above. When the folds · 24, 24 have moved into the layers 26, 26 in FIG. 6, the point d shifts to the point Q. This means that the around the membrane 8 formed circle, shown in Fig. 5, must contract accordingly. That is, the pairs of radial folds 18, 19 j 20, 21 f 22, 23, etc. are folded more so that the edge 9 contracts in its circumferential direction. The edge 9 according to the invention can flexibly expand and contract in its circumferential direction in order to freely follow a large movement of the membrane 8 until the folds 24, 24 have been moved into their parallel positions 27-27.

The operation of the rim 9 will next be described when the diaphragm 8 moves downwards in the opposite direction or from its rest position. According to Fig. 6, the points c and d of the edge 9 follow the downward movement of the membrane 8 by movement on the Curves 31 and 30 in arrow directions H and K. If the movement of the diaphragm 8 is small, points c and d move to a point T on the curve 31 and a point U, respectively on curve 30. On the other hand, if the movement of the mem-

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bran 8 is very large, points c and d move towards a point V or a point W which is essentially in the same position as the point d initially. Therefore move the folds 24, 24 first in their .Lagen 28, 28 and then in their positions 29, 29 “If the point d is in the Point U is located, the sequence of circumferential folds 13, 13 ', ..., which are shown in FIG. 5, form a correspondingly larger circle around the membrane 8. That is, in one such a case is that between the pairs of radial folds 18, 19} 20, 21 j 22, 23 etc. formed fold stretched so that the edge 9 in its circumferential direction is extended.

The edge according to the invention has a V-shaped cross-section, and the radial folds 18, 19} 20, 21} 22, 23 etc. are formed on inclined surfaces having a V-shape form. If the radial folds are not on the sloping surfaces were present, the sloping surfaces would be arbitrary vibrate, which would lead to a resonance of the edge, since the inclined surfaces are made of a soft and pliable Edge material exist. According to the invention, however, radial folds are provided on the inclined surfaces. Through the Using alternating concave and convex radial folds, these inclined surfaces are rather rigid with respect to one force exerted perpendicular to it «Therefore, these inclined surfaces cannot arbitrarily move in a perpendicular direction vibrate so that no resonance occurs in the rim.

The preceding description refers to a. Case in which the membrane moves in the direction of the axis of the electroacoustic transducer "However, the membrane does not only move in Actis © arielitung, but also in the direction perpendicular to the Aeiiae of elelitroakustischen converter _β The following Besehrelbtm ^ therefore shall look to the advantageous © Varhalteai des Eaada according to the invention in relation to its resistance against © ± ma des'E.a'tige mobility of the membrane.

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The movement of the membrane in the direction perpendicular to the axis of the electroacoustic transducer takes place in the direction of the arrow M in Fig. 6, A tendency for the diaphragm to be easily moved in such a direction would be disadvantageous, as it would lead to difficulties, e.g. B. to a displacement of the voice coil from its correct position. Therefore, such movement of the membrane must be absorbed by the edge.

This has already been described with reference to FIGS. 5 and 6 is, the edge is according to the invention by the pairs of folds 24, 24 and 25 »25 in the radial direction of the membrane formed, and the folds 24, 24 and 25, 25 are formed alternately convex and concave relative to each other. It Let it now be assumed that a force is exerted on point c in the direction M in FIG. This force wants to bend the folds 24, 24 and 25, 25 and move the point d »The folds 24, 24 and 25, 25 and the surfaces 14, 14 'and 15, 15' between the folds 24, 24 and 25 »25 are limited, but have a very high rigidity versus the force exerted in that direction. Therefore the surfaces as well as the folds are not bent, but oppose the force exerted in this direction, so that the individual sections stay in their initial position.

It can be seen that the edge according to the invention, the circumferential folds and radial folds emanating from the XTmfangsfalzen, can expand and contract like a bellows in the circumferential grooves. Balxev can Sicli the folds of the hands in the UiEfangsrieiittsEig at großes- B © - movement of MeKibran in AcliseEiric & tiajag the © © I converter ausdeli »© n and additionally aEüEOS3üaiöIts32!. _s ε © that the dar obigea moved the Menibrau Saigon lzazm. _c Fo ^ ne-r; :: tfleiten the Badialfel & e clog Jlandc- sghs ££ co? E ^ flucStsag d ± ©

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Sloping surfaces of the edge in the V-shape, prevent a Resonance of the edge and withstand a bending force in a direction perpendicular to the axis of the electroacoustic Converter is exercised. Due to the sufficient holding force of the radial folds, the edge can be in its starting position being held.

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Claims (1)

Claims Electroacoustic transducer with an edge for holding a diaphragm of the transducer, characterized in that the edge (9) has a V-like cross section and a device (13, 13 ^f ! 16, i6 ^r j 17, 17M 18, 19, 20, 21 j 22, 23), by means of which it can be expanded and contracted in its circumferential direction during axial movement of the membrane (8) in order to flexibly follow this movement of the membrane (FIGS. 3 - 6). 2o electroacoustic transducer according to claim 1, characterized in that the edge (9) has a sequence of first folds (13, 13 ¹ ) which run essentially in its center in the circumferential direction of the membrane (8) and as a zigzag line, as well as the cut edge of the V-shaped cross-section of the edge form that the edge has a pair of second folds (18, 191, 20, 21 | 22, 23) ^{starting from each point of intersection (D, D «j D n} ) of the first folds and in a radial direction Direction of the membrane (8) so that they delimit a series of inclined surfaces (14, 14 «j 15, 15 ¹ ) which form the sides of the V-shaped cross-section of the edge, and that the edge is a series of third folds ( 16, 16 ·; 17, 17 ') which connect the upper end of the second folds on each side of the first folds and run as a zigzag line in the circumferential direction of the membrane (Fig. 3 - 6) " 3. Electroacoustic transducer according to claim 1 or 2, characterized in that the edge (9) holding the diaphragm of the transducer is made of a composite material of synthetic fibers consists (Fig. 3-6). 909839/1088