JP2010278591A - Speaker unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speaker unit which can create a large sound field space even in a high sound range by high sound quality of less noise. <P>SOLUTION: In the speaker unit configured to drive a diaphragm 5 through a voice coil 3 by a magnetic circuit 2 including a pole piece 24, the diaphragm 5 is bonded to the voice coil 3 oppositely to the upper end surface of the pole piece 24 or a center cap 8 is formed on the center of the diaphragm 5 oppositely to the upper end surface of the pole piece 24. A sheet member 6 having internal loss larger than that of the pole piece 24 and having cut portions 63 radially spread from the inner peripheral part of the upper end surface of the pole piece 24 to the outer peripheral part is fixed on the upper end surface of the pole piece 24. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dynamic speaker unit having a magnetic circuit including a pole piece that generates a DC magnetic field that acts on a voice coil, and can particularly reproduce high-quality sound with less noise and create a large sound field space even in a high sound range. It is related with the speaker unit which can do.

  The speaker unit is roughly classified into a dynamic type (electrodynamic type) and a capacitor type (electrostatic type) according to a method of converting an AC electric signal into mechanical vibration, and the mainstream is a dynamic type. A dynamic speaker unit has a configuration in which a voice coil is placed in a DC magnetic field formed by a magnetic circuit including a pole piece, and a diaphragm is driven by a Lorentz force generated in the voice coil (for example, Patent Document 1).

  The magnetic circuit includes an inner magnet type and an outer magnet type, and both of them have a pole piece constituting the magnetic circuit inserted in the voice coil. In addition, there are dome type, flat type, cone type, etc. as diaphragms to be joined to the voice coil. The dome type diaphragm is entirely joined to the voice coil so as to face the upper end surface of the pole piece. Is partly opposed to the upper end surface of the pole piece and joined to the voice coil. In the cone type diaphragm, a center cap facing the upper end surface of the pole piece is mounted at the center. The upper end surface of the pole piece refers to a surface on the diaphragm side where the speaker unit is placed with the diaphragm on the upper side.

JP 2003-333688 A

  In the speaker unit as described above, when the center cap or the diaphragm facing the upper end surface of the pole piece vibrates, the sound radiated to the back side of the speaker piece is reflected on the pole piece to generate an echo sound, Resonates and generates resonance sound. The reverberant sound and resonance sound are heard as annoying noise mixed with sound directly radiated forward from the diaphragm.

  Therefore, sound absorbing material such as glass wool is filled between the pole piece on the back side of the center cap and diaphragm, but this suppresses the generation of reverberation and resonance by the pole piece. However, since the reproduced sound is muddy and the high frequency sound does not spread, it is impossible to create a large sound field with sharp directivity in the high frequency range.

  The present invention has been made in view of the circumstances as described above, and an object of the present invention is to provide a speaker unit capable of creating a large sound field space even in a high sound range with high sound quality with less noise.

  In order to achieve the above object, a speaker unit according to the present invention includes a voice coil 3 in which a conductive wire is wound around a coil bobbin 31, a magnetic circuit 2 including a pole piece 24 inserted into the voice coil 3, The diaphragm 5 joined to the tip of the voice coil 3, and the internal loss is larger than that of the pole piece 24 and the inner surface of the pole piece 24 facing the diaphragm 5 is directed from the inner periphery to the outer periphery. And a sheet member 6 having a radially extending cutout portion 63 and affixed to the facing surface.

  The diaphragm 5 is a dome-shaped diaphragm. The diaphragm 5 is a cone-shaped diaphragm having a center hole 5a communicating with the voice coil 3, and further includes a center cap 8 that covers the center hole 5a.

  The sheet member 6 is made of a plastic film, a rubber sheet, paper, a nonwoven fabric, or a woven fabric.

  According to the speaker unit of the present invention, there is provided a sheet member having a cutout portion that has an internal loss larger than that of the pole piece and radially spreads from the inner peripheral portion of the facing surface facing the diaphragm of the pole piece toward the outer peripheral portion. Because it is affixed to the opposing surface of the pole piece, the sound radiated to the back side of the diaphragm or center cap facing the opposing surface of the pole piece is attenuated to suppress the generation of resonance and reverberation by the pole piece However, the sound field can be expanded by expanding the sound radially by the action of the cutout portion that exposes the opposing surface of the pole piece.

  Particularly, in the case of a sheet member made of plastic film, rubber sheet, paper, nonwoven fabric, or woven fabric, since the material itself is not so expensive, the product cost can be suppressed and the internal loss larger than that of the pole piece can be obtained. The suppression effect of resonance sound and reverberation sound by.

Sectional drawing which shows the speaker unit which concerns on one embodiment of this invention Schematic showing the tip face of the pole piece with the seat member fixed Explanatory drawing which shows the modification of a sheet | seat member Sectional drawing which shows the example of a change of the speaker unit which concerns on one embodiment of this invention

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, referring to FIG. 1, an embodiment of the speaker unit of the present invention will be described. The speaker unit is an electrodynamic (dynamic) tweeter (for high sound). Reference numeral 1 denotes a frame of the speaker unit, and a magnetic circuit 2 (an outer magnet type in the illustrated example) is attached to the frame 1.

  The magnetic circuit 2 includes a ring-shaped magnet 21 magnetized in the thickness direction, a ring-shaped top plate 22 mounted on one magnetic pole of the magnet 21, and the other magnetic pole of the magnet 21. The back plate 23 and the pole piece 24 provided at the center of the back plate 23 are formed. A magnetic gap G on which the magnetic flux of the magnet 21 acts is formed between the pole piece 24 and the top plate 22. Has been.

  The top plate 22, the back plate 23, and the pole piece 24 serve as a yoke that collects the magnetic flux of the magnet 21 in the magnetic gap G, and the voice coil 3 is inserted into the magnetic gap G. Note that the back plate 23 and the pole piece 24 may be formed as a single unit.

  The voice coil 3 is wound by winding a conductive wire such as copper or aluminum coated with an insulating film around the outer periphery of a coil bobbin 31 made of paper or the like (a conductive nonmagnetic material such as aluminum may be used). The upper end portion of the pole piece 24 is inserted into the inner periphery thereof, and the inner peripheral surface of the top plate 22 faces the outer winding portion 32. The voice coil 3 is attached to the frame 1 via a damper 4, and is supported by the damper 4 so as to be movable in the front-rear direction (the direction of the axis passing through the center of the voice coil 3 and the vertical direction in FIG. 1). The tip is joined to the dome-shaped diaphragm 5.

  The diaphragm 5 is a dome-shaped radiator formed of paper, wood, synthetic resin such as polypropylene or polyester, aluminum or other metal, or chemical fiber. This is clearly shown in FIG. The voice coil 3 is placed on the tip of the voice coil 3 so as to face the upper end surface of the voice coil 3. The upper end surface of the pole piece 24 is a facing surface that faces the back surface of the diaphragm 5.

  According to the speaker unit configured as described above, it is well known that an audio current is passed through the voice coil 3 (more precisely, the winding portion 32) perpendicular to the magnetic field lines of the DC magnetic field generated in the magnetic gap G. As described above, the voice coil 3 vibrates by obtaining an axial excitation force, and the vibration is converted into air vibration via the diaphragm 5, so that sound can be reproduced.

  When the diaphragm 5 vibrates in the front-rear direction (vertical direction in FIG. 1), the sound radiated to the back side (rear side where the pole piece 24 is located) is reflected on the pole piece 24 to generate an echo sound, The pole piece 24 resonates and generates a resonance sound. For this reason, according to the present embodiment, the sheet member 6 instead of the conventional sound absorbing material is fixed and fixed (adhered) to the upper end surface of the pole piece 24 with an adhesive or the like.

  The sheet member 6 is a sheet having a thickness of about 0.1 to 3 mm, in particular, a non-metallic sheet made of a material different from that of the pole piece 24, and has a higher internal loss than the pole piece 24, such as polypropylene (PP) It consists of a plastic film such as polyvinyl chloride (PVC), a rubber sheet, paper, a nonwoven fabric including felt and tufted fabric, or a woven fabric. Among these, for example, the internal loss of polypropylene is 0.08, and the internal loss of paper is 0.025 to 0.055. Note that the pole piece 24 is made of a magnetic metal for the sheet member 6 of this type, and its internal loss is approximately 0.001 to 0.01 although it varies depending on the material.

  FIG. 2 shows an upper end surface of the pole piece 24 to which the sheet member 6 as described above is fixed. As is apparent from FIG. 2, the sheet member 6 has the same circular shape as the upper end surface of the pole piece 24, and has a shape anisotropy that does not cover the entire upper end surface of the pole piece 24. Specifically, in a form in which the annular portion 61 along the outer periphery of the pole piece 24 and a plurality of (four in the illustrated example) projecting piece portions 62 extending from the inner peripheral edge of the annular portion 61 toward the center thereof are connected. A space between the projecting piece portions 62 is notched and opened as a cutout portion 63. The cut-out portion 63 is formed inside the annular portion 61 and between the projecting piece portions 62, spreads radially from the inner peripheral portion of the upper end surface of the pole piece 24 toward the outer peripheral portion, and the annular portion 61. Are formed continuously with the concentric arc portion 64.

  According to the sheet member 6 as described above, the annular portion 61 and the projecting piece portion 62 covering the upper end surface of the pole piece 24 absorb the sound radiated to the back side of the diaphragm 5 and resonate with the pole piece 24. While suppressing the sound and the reverberant sound, the cutout portion 63 and the circular arc portion 64 that expose the upper end surface of the pole piece 24 do not hinder the propagation of the high frequency range component by the pole piece 24. In particular, the cutout portion 63 reduces the high frequency range component. It acts to expand the sound field by spreading it radially. In short, the seat member 6 gives acoustic anisotropy to the pole piece 24 as a whole, and suppresses the resonance sound and reverberation sound caused by the pole piece 24, while the high frequency range is set in the radial direction (up / down / left / right) of the upper end surface of the pole piece 24. Direction).

  Here, when comparing the acoustic performance of the speaker unit of the present embodiment having the sheet member 6 as described above and the conventional speaker unit not having the sheet member 6, there is a great difference between the two in terms of the directivity pattern in the horizontal direction. However, the speaker unit of the present embodiment has less noise and higher sound quality than the conventional speaker unit, has a good sound field feeling in the high sound range, and the superiority in hearing is obvious. there were.

  Although a preferred example of the present embodiment has been described above, the sheet member 6 is not limited to the form as shown in FIG. 2, but may be configured as shown in FIGS. 3 (a) to 3 (e), for example.

  Furthermore, in the above example, the speaker unit according to the present embodiment has been described as a dome type speaker. However, in the present invention, a planar speaker in which a part of the diaphragm faces the tip surface of the pole piece 24 or the pole piece 24 is provided. The present invention can also be applied to a cone type speaker having a center cap corresponding to the front end surface.

  FIG. 4 shows an example applied to a cone type speaker. In FIG. 4, parts having the same structure and function as those of the dome type speaker shown in FIG.

  Here, the cone type speaker shown in FIG. 4 is a full range type or a woofer, and its diaphragm 5 is made of paper, wood, synthetic resin such as polypropylene or polyester, aluminum or other metals, or chemical fibers. A circular center hole 5 a that communicates with the voice coil 3 is formed at the inner center portion that is a cone type and is joined to the voice coil 3. The outer periphery of the cone-shaped diaphragm 5 on the large diameter side is supported by the frame 1 via an edge 7 that allows the diaphragm 5 to move in the front-rear direction.

  Further, a center cap 8 that covers the center hole 5 a is attached to the center of the diaphragm 5 so as to face the upper end surface of the pole piece 24. The center cap 8 is a dome-shaped member larger than the center hole 5a of the diaphragm 5, and is formed of paper, wood, metal, or a synthetic resin such as polypropylene or polyester, and the outer periphery thereof is the same as the diaphragm 5. While being fixed to the diaphragm 5 with an adhesive, the tip of the voice coil 3 is also joined to the center cap 8. In the configuration of FIG. 4, the upper end surface of the pole piece 24 is a facing surface that faces the rear surfaces of the diaphragm 5 and the center cap 8.

  Note that the center cap 8 has a dustproof function for preventing dust from entering the magnetic circuit 2, and the center cap 8 itself vibrates with the diaphragm 5, thereby affecting the acoustic characteristics. In particular, when the center cap 8 vibrates in the front-rear direction, the sound radiated to the back side (the rear side where the pole piece 24 is located) is reflected on the pole piece 24 to generate an echo sound, or the pole piece 24 resonates. Resonance sound is generated. Therefore, also in such a speaker unit, the sheet member 6 as described above is fixed to the upper end surface of the pole piece 24 with an adhesive or the like in the same manner as in the above example.

  Therefore, even in such a cone type speaker, it is possible to expand the sound field in the same direction by spreading the sound in the radial direction (up / down / left / right direction) of the pole piece 24 while suppressing the resonance sound and the reverberation sound by the pole piece 24.

2 Magnetic circuit 24 Pole piece 3 Voice coil 31 Coil bobbin 32 Winding part 5 Diaphragm 5a Center hole 6 Sheet member 63 Cutout part 8 Center cap

Claims (4)

A voice coil formed by winding a conductive wire around a coil bobbin;
A magnetic circuit including a pole piece inserted into the voice coil;
A diaphragm joined to the tip of the voice coil;
A sheet that has an internal loss larger than that of the pole piece and that has a cutout portion that radially extends from the inner peripheral portion of the opposing surface of the pole piece facing the diaphragm to the outer peripheral portion, and is attached to the opposing surface. Members,
A speaker unit comprising: The speaker unit according to claim 1, wherein the diaphragm is a dome-shaped diaphragm. 2. The speaker unit according to claim 1, wherein the diaphragm is a cone-shaped diaphragm having a center hole communicating with the voice coil, and further includes a center cap that covers the center hole. The speaker unit according to claim 1, wherein the sheet member is made of a plastic film, a rubber sheet, paper, a nonwoven fabric, or a woven fabric.

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