Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JP2010278590 The present invention provides a speaker unit capable of creating a large sound field space even in a high frequency range with high sound quality with little noise. A speaker unit is configured to drive a diaphragm (5) through a voice coil (3) by a magnetic circuit (2) including a pole piece (24), and the diaphragm (5) faces an upper end face of the pole piece (24). A center cap 8 is provided at the center of the diaphragm 5 opposite to the upper end face of the pole piece 24. On the upper end surface of the pole piece 24 is fixed an acoustic anisotropic member 6 having anisotropy in the propagation velocity of sound waves and having an internal loss larger than that of the pole piece 24. The acoustic anisotropy member 6 is a wood piece such as a hippo, and its fiber direction is crossed to the axis of the pole piece 24. [Selected figure] Figure 1 スピーカユニット [0001] The present invention relates to a dynamic type speaker unit provided with a magnetic circuit including a magnetic circuit including a pole piece that generates a direct current magnetic field acting on a voice coil, and can reproduce high quality sound with particularly low noise and create a large sound field space even in a high sound range. The present invention relates to a speaker unit that can be [0002] 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 alternating current electric 12-05-2019 1 signal into mechanical vibration, and the main stream is a dynamic type. A dynamic speaker unit has a voice coil placed in a direct current magnetic field formed by a magnetic circuit including a pole piece, and is configured to drive a diaphragm by Lorentz force generated there (for example, Patent Document 1). [0003] The magnetic circuit is of an inner magnet type or an outer magnet type, and in each of the voice coils, a pole piece constituting a magnetic circuit is inserted. In addition, the diaphragms joined to the voice coil include a dome type, a flat type, a cone type, etc., and the whole of the dome type diaphragm is bonded to the voice coil facing the upper end face of the pole piece and the planar type diaphragm Is partially joined to the voice coil so as to face the upper end face of the pole piece, and in the case of a cone type diaphragm, a center cap opposite to the upper end face of the pole piece is mounted at the center thereof. The upper end surface of the pole piece refers to the surface on the diaphragm side in a state in which the speaker unit is placed with the diaphragm on the upper side. [0004] JP 2003-333688 A [0005] In the speaker unit as described above, when the center cap or diaphragm opposed to the upper end face of the pole piece vibrates, the sound radiated to the back side of them vibrates on the pole piece to generate echo sound, or the pole piece It resonates to generate resonance sound. The echo sound and resonance sound are mixed with the sound directly radiated forward from the diaphragm and are heard as offensive noise. [0006] Therefore, it is also practiced to fill a sound absorbing material such as glass wool between the pole cap and the center cap or the back side of the diaphragm, but according to this, it is 12-05-2019 2 necessary to suppress the generation of echo and resonance noise by the pole piece. Even if it is possible, the reproduced sound is aurally turbid and the high-range sound does not spread, so the directivity in the high range is sharp and a large sound field space can not be created. [0007] The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a speaker unit capable of creating a large sound field space with high sound quality with little noise and high pitch. [0008] In order to achieve the above object, a speaker unit according to the present invention comprises: a voice coil 3 formed by winding a conductive wire around a coil bobbin 31; a magnetic circuit 2 including a pole piece 24 inserted inside the voice coil 3; The diaphragm 5 joined to the tip of the voice coil 3 has an anisotropy in the propagation velocity of the sound wave and an internal loss larger than that of the pole piece 24 so as to face the diaphragm 5 of the pole piece 24 And an acoustic anisotropic member 6 fixed to the opposite surface. [0009] The diaphragm 5 is characterized by being a dome-shaped diaphragm. The diaphragm 5 is a cone-shaped diaphragm having a central hole 5a communicating with the voice coil 3, and further includes a center cap 8 covering the central hole 5a. [0010] In addition, the acoustic anisotropic member 6 is characterized in that it is a wood piece arranged so that the fiber direction intersects the direction orthogonal to the opposing surface of the pole piece 24. Furthermore, the wood piece includes a first wood piece 6a and a second wood piece 6b arranged so that the fiber directions are orthogonal to each other in the plane of the opposing surface of the pole piece 24 or in a plane parallel to the opposing surface. It features. 12-05-2019 3 [0011] According to the speaker unit according to the present invention, the acoustic anisotropic member having anisotropy in the propagation velocity of the sound wave and the internal loss larger than that of the pole piece is fixed to the opposing surface of the pole piece facing the diaphragm. Thus, the sound radiated from the diaphragm or center cap opposite to the opposing surface of the pole piece to the back side is attenuated to suppress the generation of resonance noise or echo due to the pole piece, and by the acoustic anisotropic member. The sound field can be expanded by spreading the sound in the direction in which the propagation speed of the sound wave is high. [0012] In particular, since wood chips are used as the acoustic anisotropic member, the product cost can be suppressed, and the propagation speed of the sound wave is high in the fiber direction of the wood pieces, and the fiber direction intersects the direction orthogonal to the facing surface of the pole piece As such, the reproduction sound can be spread in the fiber direction intersecting the direction orthogonal to the facing surface. [0013] In addition, a wood piece as the acoustically anisotropic member includes a first wood piece and a second wood piece arranged so that the fiber directions are orthogonal to each other in the plane of the facing surface of the pole piece or in the plane parallel to the facing surface. In this case, the reproduced sound can be spread in two directions (upper, lower, left, and right directions) corresponding to the fiber directions of both pieces of wood. [0014] Sectional drawing which shows the speaker unit which concerns on one embodiment of this invention Schematic which shows the front end surface of the pole piece which fixed the acoustic anisotropic member, Explanatory drawing which shows the fiber direction of the wood piece which comprises an acoustic anisotropic member acoustic difference Explanatory drawing which shows the example of a change of a directional member, sectional drawing which shows the example of a change of the speaker unit concerning one embodiment of the present invention [0015] 12-05-2019 4 Hereinafter, an embodiment of the present invention will be described in detail based on the drawings. First, referring to FIG. 1, an embodiment of a speaker unit according to 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 (external magnet type in the illustrated example) is attached to the frame 1. [0016] The magnetic circuit 2 is mounted on a ring-shaped magnet 21 magnetized in the thickness direction, a ring-shaped top plate 22 mounted on one of the magnetic poles of the magnet 21, and the other magnetic pole of the magnet 21. And a pole piece 24 provided at the center of the back plate 23. A magnetic gap G in which the magnetic flux of the magnet 21 acts is formed between the pole piece 24 and the top plate 22. It is done. [0017] The top plate 22, the back plate 23, and the pole piece 24 become a yoke for collecting the magnetic flux of the magnet 21 in the magnetic gap G, and the voice coil 3 is inserted in the magnetic gap G. The back plate 23 and the pole piece 24 may be integrally formed. [0018] The voice coil 3 is formed by winding a conductive wire such as copper or aluminum coated with an insulating film around the outer periphery of a non-conductive (a conductive nonmagnetic material such as aluminum may be used) made of paper or the like. The upper end portion of the pole piece 24 is inserted into the inner periphery of the wire portion 32, and the inner peripheral surface of the top plate 22 faces the winding portion 32 of the outer periphery. 12-05-2019 5 The voice coil 3 is attached to the frame 1 via the damper 4 and supported movably in the frontrear direction (the direction of the axis passing through the center of the voice coil 3 and in the vertical direction in FIG. 1) by the damper 4 Its tip is joined to the dome-shaped diaphragm 5. [0019] The diaphragm 5 is a dome-shaped radiator formed of paper, wood, or a synthetic resin such as polypropylene or polyester, aluminum or other metal, or chemical fiber, as is apparent from FIG. 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 an opposing surface opposed to the back surface of the diaphragm 5. [0020] Then, according to the speaker unit configured as described above, it is known that the voice current flows in the voice coil 3 (precisely, the winding portion 32) orthogonal to the magnetic lines of the direct current magnetic field generated in the magnetic gap G. Thus, the voice coil 3 vibrates by obtaining an oscillating force in the axial direction, and the vibration is converted to air vibration through the diaphragm 5 so that sound can be reproduced. [0021] When the diaphragm 5 vibrates in the front-rear direction (vertical direction in FIG. 1), the sound radiated to the back side (the rear side where the pole piece 24 is located) is reflected to the pole piece 24 to generate echo sound. The pole piece 24 resonates to generate a resonant sound. Therefore, according to the present embodiment, the acoustic anisotropic member 6 instead of the conventional sound absorbing material is fixed (fixed) to the upper end surface of the pole piece 24 with an adhesive or the like. [0022] 12-05-2019 6 The acoustic anisotropic member 6 has anisotropy in the propagation speed of sound waves (hereinafter referred to as the speed of sound) and has an internal loss larger than that of the pole piece 24. The pole piece 24 is made of magnetic metal and its internal loss varies depending on the material, but is about 0.001 to 0.01. Those having a larger internal loss than the pole piece 24 of that kind and having anisotropy in the speed of sound include pieces of wood in which fibers such as hippopotamus, china or beech extend along one direction. Their internal loss is 0.02 to 0.03, and the speed of sound is 4.5 to 6 km / s in the fiber direction (longitudinal direction), and 2 to 2.5 km / s in the direction orthogonal to the fiber direction (lateral direction) It is. In particular, as the above-mentioned wood chip, a grained grain material in which grain appears parallel is suitably used, and for this purpose, it is also possible to use plate grain wood or bamboo which is plate-shaped by hot pressing. In the wood grain, the grain by the annual rings appears in a non-parallel state, but the fiber direction is constant although slightly inclined with respect to the board surface. Moreover, it is preferable that a wood piece as the acoustic anisotropic member 6 has a plate shape having a predetermined thickness (about 5 mm in this example), and even if it is a sheet shape having a thickness of 0.1 to 1 mm. Good. [0023] FIG. 2 shows the upper end surface of the pole piece 24 to which the acoustic anisotropic member 6 made of wood pieces as described above is fixed. The arrows in the figure indicate the fiber direction of the wood piece as the acoustic anisotropic member 6. As apparent from FIG. 2, the acoustically anisotropic member 6 made of wood pieces is a rectangular plate having a size that fits within the upper end face of the pole piece 24, and the fiber direction is perpendicular to the axis of the pole piece 24 (upper face It is arranged to intersect (orthogonal to) the direction. [0024] The acoustic anisotropic member 6 as described above attenuates the sound radiated to the back side of the diaphragm 5 because the internal loss thereof is larger than that of the pole piece 24, and the resonance sound or echo sound by the pole piece 24 Can be suppressed. [0025] In particular, FIG. 2A shows a state in which the acoustic anisotropic member 6 is fixed so that the fiber direction is in the vertical direction (vertical direction) in the usage mode of the speaker unit. The radiated sound spreads in the fiber direction, and the sound field expansion in the same 12-05-2019 7 direction (vertical direction) becomes remarkable. [0026] Further, FIG. 2 (b) is a state in which the acoustic anisotropic member 6 is fixed so that the fiber direction becomes the horizontal direction (horizontal direction) in the usage mode of the speaker unit. The radiated sound spreads in the fiber direction, and the sound field expansion in the same direction (left and right direction) becomes remarkable. [0027] In addition, when the acoustic performance of the speaker unit of the present embodiment provided with the acoustic anisotropy member 6 as described above and the conventional loudspeaker unit without the acoustic anisotropy member 6 is compared, the directivity pattern in the horizontal direction is obtained. Although the speaker unit of the present embodiment has less noise and high sound quality compared to the conventional speaker unit, and a good sense of sound field in the high frequency range, the auditory sense is good. The superiority was clear. [0028] Although the preferred embodiment of the present invention has been described above, the acoustic anisotropic member 6 is not limited to a rectangular shape, and may be a circular plate having the same shape and size as the upper end surface of the pole piece 24. Also, the wood piece as the acoustic anisotropic member 6 is not limited to the fiber direction being directed vertically and horizontally. [0029] For example, as shown in FIG. 3, regarding the left and right speaker units L and R used for stereo reproduction, the acoustic anisotropic member 6 is fixed so that the fiber direction is inclined in a plane parallel to the upper end face of the pole piece 24 The fiber direction of the acoustic anisotropic member 6 in both speaker units L and R may cross in a V shape. According to this, it is possible to expand the sound field space in the up, down, left, and right 12-05-2019 8 directions as indicated by the one-dot chain line in FIG. [0030] Further, as shown in FIG. 4A, the acoustic anisotropic member 6 is constituted by the first wood piece 6a and the two second wood pieces 6b arranged so that the fiber directions are orthogonal to each other in the same plane, The two pieces of wood 6a and 6b may be arranged and fixed in the same plane with the upper end face of the pole piece 24 so that the respective fiber directions are orthogonal to each other in the plane of the upper end face of the pole piece 24 Even in such a mode, the sound field space can be expanded in the vertical and horizontal directions. FIG. 4 (b) shows that each fiber direction is orthogonal in a plane parallel to the upper end face of the pole piece 24 by overlapping the first wood piece 6a on the second wood piece 6b. Also in the mode shown in FIG. 4B, the sound field space can be expanded in the vertical and horizontal directions. [0031] Furthermore, although the speaker unit according to the present embodiment has been described as a dome-shaped speaker in the above example, in the present invention, the flat panel speaker in which a part of the diaphragm faces the upper end surface of the pole piece or the upper end surface of the pole piece It can apply also to a cone type speaker etc. which have a center cap which counters. [0032] FIG. 5 shows an example applied to a cone type speaker. In FIG. 5, the parts having the same structure and function as the dome-shaped speaker shown in FIG. 1 are assigned the same reference numerals and detailed explanations thereof will be omitted. 12-05-2019 9 [0033] Here, the cone type speaker shown in FIG. 5 is a full range type or woofer, and its diaphragm 5 is made of paper, wood, or a synthetic resin such as polypropylene or polyester, aluminum or other metal, or chemical fiber, etc. A circular central hole 5a communicating with the voice coil 3 is formed in an inner central portion which is of a cone shape and joined to the voice coil 3. Further, the outer periphery of the cone-shaped diaphragm 5 on the large diameter side is supported by the frame 1 via an edge 7 which allows the movement of the diaphragm 5 in the front-rear direction. [0034] Further, at the center of the diaphragm 5, a center cap 8 covering the center hole 5a is mounted facing 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 propylene or polyester like the diaphragm 5, and the outer periphery is While being fixed to the diaphragm 5 with an adhesive, the tip of the voice coil 3 is also bonded to the center cap 8. In the configuration of FIG. 5, the upper end surface of the pole piece 24 is an opposing surface opposed to the back surface of the diaphragm 5 and the center cap 8. [0035] The center cap 8 has a dustproof function to prevent dust from invading the magnetic circuit 2, and the center cap 8 itself also vibrates along with the diaphragm 5 to affect the acoustic characteristics. In particular, when the center cap 8 vibrates in the back and forth direction, the sound radiated to the back side (the rear where the pole piece 24 is located) is reflected to the pole piece 24 to generate echo sound, or the pole piece 24 resonates. It generates resonance noise. For this reason, also in such a speaker unit, the acoustic anisotropic member 6 as described above is fixed to the upper end surface of the pole piece 24 in the same manner as in the above example, using an adhesive or the like. [0036] Therefore, it is possible to spread the sound in the fiber direction of the wood piece as the acoustic anisotropic member 6 and to expand the sound field in the same direction while 12-05-2019 10 suppressing the resonance sound and echo sound by the pole piece 24 even with the cone type speaker concerned. . [0037] DESCRIPTION OF SYMBOLS 2 Magnetic circuit 24 pole piece 3 voice coil 31 coil bobbin 32 winding part 5 diaphragm 5a center hole 6 acoustic anisotropy member 6a 1st wood piece 6b 2nd wood piece 8 center cap 12-05-2019 11
© Copyright 2021 DropDoc