LOUDSPEAKER WITH CLOSED MEMBRANE AND RELATIVE ASSEMBLY METHOD

Abstract

An assembly method of a loudspeaker with closed membrane provides for preassembling a mobile unit having two centering devices fixed to a voice coil; pre-assembling a fixed unit that has a basket fixed to a magnetic unit, assembling the mobile unit in the fixed unit, by a centering device; extracting the centering device and fixing a closed membrane to the voice coil and to the basket.

Claims

1. Assembly method of a closed membrane loudspeaker comprising the following steps: pre-assembly of a mobile unit provided with a voice coil comprising a cylindrical support whereon at least one winding is wound; pre-assembly of a fixed unit comprising a basket and a magnetic unit provided with a lower polar plate with a core, a magnet disposed around the core and an upper polar plate disposed on the magnet and around the core in such manner to generate an air gap; use of a centering device with cylindrical shape, which is inserted into the cylindrical support of the voice coil and fitted onto the core of the lower polar plate, in such a way to center the voice coil in the air gap; gluing the mobile unit to the basket of the fixed unit; extracting the centering device from the voice coil; and gluing an edge of a closed membrane to the basket and gluing a central portion of the closed membrane to the cylindrical support of the voice coil; wherein said pre-assembly step of the mobile unit comprises the fixing of a first centering device and of a second centering device to the cylindrical support of the mobile coil; and said step of gluing the mobile unit to the basket of the fixed unit comprises the gluing of the first centering device and of the second centering device to the basket, in such manner that the two centering devices are disposed along parallel planes to guarantee a centering of the voice coil in the air gap and minimize a first distance between the external surface of the core and the internal surface of the cylindrical support of the voice coil and a second distance between the external surface of the winding of the voice coil and the internal surface of the upper polar plate.

2. The method of claim 1, wherein: each centering device comprises an internal ring, an external ring and a plurality of elastic elements that connect the external ring to the internal ring; said pre-assembly step of the mobile unit comprises the fixing of the internal ring of each centering device to the cylindrical support of the mobile coil; said step of gluing the mobile unit to the basket of the fixed unit comprises the gluing of the external ring of each centering device to a first annular shoulder and to a second annular shoulder of the basket; wherein the first and the second annular shoulder of the basket are disposed along parallel planes at different levels.

3. The method of claim 2, wherein said gluing of the edge of the closed membrane to the basket comprises the gluing of the edge of the closed membrane to a third annular shoulder of the basket, wherein the first, the second and the third annular shoulders of the basket are disposed along parallel planes at different levels.

4. Loudspeaker with closed membrane comprising: a magnetic unit having a lower polar plate with a core, a magnet disposed around the core and an upper polar plate disposed on the magnet and around the core in such a way to generate an air gap; a basket fixed to the magnetic unit; a voice coil comprising a cylindrical support whereon at least one winding is wound, said cylindrical support having a through axial hole; a first centering device directly fixed to the cylindrical support of the voice coil and to the basket, in such a way to center the voice coil in the air gap; only one closed membrane, which is made in one piece and centrally fixed directly to the cylindrical support of the voice coil and peripherally fixed to an edge fixed to the basket, so that said closed membrane covers the through axial hole of the cylindrical support; and a second centering device directly fixed to the cylindrical support of the voice coil and to the basket in such manner that the two centering devices are disposed along parallel planes, to guarantee a centering of the voice coil in the air gap and minimize a first distance between the external surface of the core and the internal surface of the cylindrical support of the voice coil and a second distance between the external surface of the winding of the voice coil and the internal surface of the upper polar plate.

5. The loudspeaker of claim 4, wherein each centering device comprises an internal ring, an external ring and a plurality of elastic elements that connect the external ring to the internal ring; the internal ring of each centering device being fixed to the cylindrical support of the mobile coil; the external ring of each centering device being fixed to a first annular shoulder and to a second annular shoulder of the basket; wherein the first and the second annular shoulder of the basket are disposed along parallel planes at different levels.

6. The loudspeaker of claim 5, wherein said basket comprises a third annular shoulder, wherein the first, the second and the third annular shoulder of the basket are disposed along parallel planes at different levels.

7. The loudspeaker of claim 4, wherein: said voice coil has a travel lower than 3 mm; said first distance is lower than 0.2 mm; and said second distance is lower than 0.3 mm.

8. The loudspeaker of claim 4, wherein: said voice coil has a travel lower than 3-8 mm; said first distance is lower than 0.25 mm; and said second distance is lower than 0.5 mm.

9. The loudspeaker of claim 4, wherein: said voice coil has a travel lower than 8-20 mm; said first distance is lower than 0.35 mm; and said second distance is lower than 0.6 mm.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0047] Additional features of the invention will appear manifest from the detailed description below, which refers to merely a illustrative, not limiting embodiment, as illustrated in the attached figures, wherein:

[0048] FIGS. 1-5 are diagrammatic axial views showing an assembly method of a loudspeaker with open membrane according to the prior art;

[0049] FIG. 6 is a diagrammatic axial view of a loudspeaker with open membrane, in assembled condition, according to the prior art;

[0050] FIG. 6A is an enlarged view of a detail of the loudspeaker of FIG. 6;

[0051] FIGS. 7-11 are diagrammatic axial views showing an assembly method of a loudspeaker with closed membrane, according to the prior art;

[0052] FIG. 12 is a diagrammatic axial view of a loudspeaker with closed membrane, in assembled condition, according to the prior art;

[0053] FIG. 12A is an enlarged view of a detail of the loudspeaker of FIG. 12;

[0054] FIGS. 13-17 are diagrammatic axial views showing an assembly method of a loudspeaker with closed membrane, according to the invention;

[0055] FIG. 18 is a diagrammatic axial view of a loudspeaker with closed membrane, in assembled condition, according to the invention;

[0056] FIG. 18A is an enlarged view of a detail of the loudspeaker of FIG. 18.

DETAILED DESCRIPTION OF THE INVENTION

[0057] With reference to FIG. 13, according to the invention, the mobile unit (A) comprises a first centering device (3) and a second centering device (3) that are directly fixed to the cylindrical support (20) of the voice coil (2). Such a mobile unit (A) is pre-assembled.

[0058] For illustrative purposes, each centering device (3, 3) comprises an internal ring (30), an external ring (31) and a plurality of elastic elements (32) that connect the external ring to the internal ring

[0059] With reference to FIG. 14, the internal ring (30) of each centering device (3, 3) is fixed to the cylindrical support (2) with glue, in such a way that the centering devices (3, 3) are arranged according to two spaced-out horizontal planes.

[0060] The external ring of the first centering device (3) has a higher diameter than the external ring of the second centering device (3).

[0061] The fixed unit (B) is pre-assembled. Said fixed unit (B) is substantially similar to a traditional fixed unit. The only difference is represented by the fact that the basket (5) comprises three annular shoulders (51, 52, 53) disposed at three different height levels; [0062] a first annular shoulder (51) to receive the external ring of the first centering device (3), [0063] a second annular shoulder (52) to receive the external ring of the second centering device (3), [0064] a third annular shoulder (53) to receive the edge (11) of the membrane.

[0065] The three annular shoulders (51, 52, 53) are disposed on parallel horizontal planes. The third shoulder (53) is the highest and has the largest diameter. The second shoulder (52) is the lowest and has the smallest diameter.

[0066] With reference to FIG. 15, the centering device (6) is inserted into the cylindrical support (20) of the voice coil and fitted on the core (41) of the lower polar plate.

[0067] The external rings of the first and the second centering device (3, 3) are glued with glue, respectively on the first annular shoulder (51) and on the second annular shoulder (52) of the basket. It must be noted that the voice coil (2) is connected to the basket (5) on two spaced-out gluing planes, in such a way as to ensure a perfect centering of the voice coil (2) in the air gap (T).

[0068] With reference to FIG. 16, after the polymerization of the glue, the centering device (6) is removed, extracting it from the top of the cylindrical support of the voice coil (2).

[0069] With reference to FIG. 17, after extracting the centering device, the membrane (100) is fixed to the fixed unit (B), by gluing the edge (11) of the membrane to the third shoulder (53) of the basket (5) and the upper edge of the cylindrical support (20) of the voice coil to a central portion of the membrane (100). Therefore, the membrane (100) is directly fixed to the cylindrical support (20) of the voice coil and is a closed membrane because it covers the axial hole of the cylindrical support (20) of the voice coil. It must be noted that the loudspeaker comprises only one membrane (100) that is made in one piece.

[0070] With reference to FIGS. 18 and 18A, in such a case of loudspeaker with closed membrane (100) according to the invention, a first distance (T5) is provided between the external surface of the core (41) and the internal surface of the cylindrical support (2) of the voice coil, and a second distance (T6) is provided between the external surface of the winding (21) of the voice coil and the internal surface of the upper polar plate (43).

[0071] In such a case, the distances (T5, T6) obtained with the loudspeaker with closed membrane according to the invention are considerably lower than the distances (T3, T4) obtained with loudspeakers with closed membrane according to the prior art and are similar to the distances (T1, T2) obtained with loudspeakers with open membrane.

[0072] In view of the above, the loudspeaker with closed membrane according to the invention guarantees a better performance than a loudspeaker with closed membrane according to the prior art, with the same dimensions and the same cost of the magnetic unit.

[0073] Table 1 shows the values of the distances (T1, T2, 5 T3, T4, T5, T6) respectively measured in a loudspeaker with open membrane, in a loudspeaker with closed membrane according to the prior art and in a loudspeaker with closed membrane according to the invention, according to the travel of the voice coil. All numerical values in the table are expressed in millimeters.

[0074] The term travel indicates the axial translation of the voice coil relative to a central fixed horizontal plane, applying a sinusoidal signal to the winding of the voice coil with power equal to the rated power of the loudspeaker.

TABLE-US-00001 TABLE 1 Loudspeaker Loudspeaker with closed with closed Loudspeaker membrane membrane with open according according to membrane to prior art invention Travel T1 T2 T3 T4 T5 T6 <+3 0.1-0.2 0.15-0.3 >0.2 >0.3 0.1-0.2 0.15-0.3 3-8 0.17-0.25 0.3-0.5 >0.25 >0.5 0.17-0.25 0.3-0.5 8-20 0.25-0.35 0.4-0.6 >0.35 >0.6 0.25-0.35 0.4-0.6

[0075] As shown in Table 1, the distances (T5, T6) obtained with the loudspeaker with closed membrane according to the invention are considerably lower than the distances (T3, T4) obtained with loudspeakers with closed membrane according to the prior art and equal to the distances (T1, T2) obtained with loudspeakers with open membrane.

[0076] The differences between the loudspeaker with closed membrane according to the invention and the loudspeaker with closed membrane according to the prior art increase when the travel of the voice coil increases.

[0077] The loudspeaker according to the invention, with a travel of the voice coil lower than mm, has a first distance (T5) lower than 0.2 mm and a second distance (T6) lower than 0.3 mm.

[0078] The loudspeaker according to the invention, with a travel of the voice coil comprised in the range3-8 mm, has a first distance (T5) lower than 0.25 mm and a second distance (T6) lower than 0.5 mm.

[0079] The loudspeaker according to the invention, with a travel of the voice coil comprised in the range8-20 mm, has a first distance (T5) lower than 0.35 mm and a second distance (T6) lower than 0.6 mm.

[0080] Numerous equivalent variations and modifications can be made to the present embodiments of the invention, which are within the reach of an expert of the field and fall in any case within the scope of the invention as disclosed by the attached claims.