JP2010226405A - Loudspeaker device for low-pitched sound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a loudspeaker device for low-pitched sound that reduces generation of air noise with a higher frequency than an original sound-producing frequency in a structure wherein an opposite member is provided ahead of a vibration unit that vibrates at low frequency and large amplitude. <P>SOLUTION: A sound-producing unit 10 is housed in the internal space 3 of a case 2, and the vibration unit 16 is exposed on an inner bottom wall 2f. An opposite member 4 is arranged opposite to the vibration unit 16, and a sound pressure space 5 is formed between the vibration unit 16 and the opposite member 4 and sound-producing windows 6 are open on both sides of the sound pressure space 5. A shock absorbing material 21 made of foaming material and opposite to the vibration unit 16 is provided on the surface of the opposite member 4, so that the vibration of air caused by the vibration of the vibration unit 16 is eliminated as the internal loss of the shock absorbing material 21, thus reducing air noise. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a low-frequency speaker device used for in-vehicle use, and more particularly to a speaker device capable of reducing so-called air noise when a vibration part vibrates at a low frequency.

  As described in Patent Literature 1 and Patent Literature 2 below, a speaker device for bass used for in-vehicle use or the like has an adapter and a part of a case facing each other with a gap in front of a diaphragm. Yes.

  In the speaker device described in Patent Document 1, the space between the diaphragm and the adapter is caused to function as an acoustic load unit, thereby increasing the bass effect. In the speaker device described in Patent Document 2, the front of a weight that vibrates with a large amplitude at a low frequency is covered with a case and protected.

JP-A-10-23583 JP 2002-78052 A

  As described in each patent document, the low-frequency loudspeaker device enhances the low-frequency effect by closing the front of the diaphragm or protects the diaphragm that vibrates with a large amplitude.

  However, in this case, the air pressure generated in front of the diaphragm, that is, the sound pressure, causes the air in front of the diaphragm to strike the wall surface and flow in the lateral direction. In addition, air noise is likely to occur due to air moving in a narrow space in front of the diaphragm.

  Since this air noise includes a sound having a frequency higher than that of the low sound to be generated by the diaphragm, it becomes annoying when listening to music or the like.

  The present invention solves the above-described conventional problems, and suppresses the generation of air noise due to sound pressure applied to the space between the vibrating portion and the facing member in a structure in which the facing member is provided in front of the vibrating portion. An object of the present invention is to provide a low-frequency speaker device.

The present invention is provided with a sounding unit having a magnetic drive part and a vibration part that is vibrated by the magnetic drive part, and a case having an internal space for housing the sounding unit. In the speaker device in which the vibration part is exposed,
A facing member facing the vibrating portion at a certain distance from the wall portion on the sound generation side of the case is provided, and a space between the wall portion and the facing member opens toward the side of the case. And
A cushioning material formed of a foam material is provided on the surface of the facing member that faces the vibrating portion with a space from the vibrating portion.

  In the speaker device for bass according to the present invention, since the facing member is provided in front of the vibrating portion, the effect of releasing the air flow between the vibrating portion and the facing member in the outer circumferential direction of the vibrating portion is enhanced. Furthermore, the bass effect can be enhanced by suppressing unnecessary air noise generated in a narrow space between the vibrating portion and the facing member. Moreover, the vibration part which vibrates with a large amplitude at a low frequency can be protected by the facing member. In addition, since the opposing member is provided with a cushioning material formed of a foam material facing the vibrating part, air vibrations having a relatively high frequency due to the air flow between the vibrating part and the opposing member are buffered. It is easily digested as an internal loss due to elastic deformation of the material. Therefore, so-called air noise generated at a relatively high frequency can be reduced.

  In the present invention, it is preferable that the distance between the surface of the cushioning material and the surface of the vibration part is longer than the maximum amplitude of the vibration part toward the space.

  In the present invention, it is preferable that the outer edge of the cushioning material is circular, and the outer edge of the cushioning material is located closer to the center of the vibrating part than the outer edge of the vibrating part.

  By configuring as described above, a protruding portion such as a damper provided on the outer periphery of the vibrating portion is less likely to hit the cushioning material.

  In the present invention, it is preferable that an outer edge of the cushioning material is circular, and a recess that is recessed toward the hole or the facing member is formed in the center of the cushioning material.

  In the case where a cap portion having a protruding shape is provided in the center of the vibration portion, the cap or the concave portion is not easily hit by forming the hole or the concave portion.

  Furthermore, the present invention is such that the surface of the cushioning material that faces the vibrating portion has an inclined surface that is tilted in the same direction as the shape of the surface of the vibrating portion. Is difficult to hit.

  The low-frequency speaker device of the present invention can reduce air noise during vibration of the vibration part and improve the quality of low-pitched sound even if a counter member in front of the vibration part is provided.

The perspective view which shows the speaker apparatus for low sounds of embodiment of this invention, Sectional drawing which cut | disconnected the speaker apparatus shown in FIG. 1 by the II-II line | wire, Sectional drawing which cut | disconnected the speaker apparatus shown in FIG. 1 by the III-III line | wire, Sectional drawing which shows the modification of the said speaker apparatus, A diagram for explaining the effect of the present invention,

  The speaker device shown in FIGS. 1 to 3 is for bass and is mainly used for in-vehicle use. The speaker device 1 is used with the Z1 side shown in FIG.

  The speaker device 1 has a case 2 formed of a synthetic resin material or the like. The case 2 has a ceiling wall 2a, side walls 2b and 2b facing each other in the left-right direction (X direction), and side walls 2c and 2c facing each other in the front-rear direction (Y direction). As shown in FIG. 3, bottom walls 2d and 2d that are continuous with the side walls 2c and 2c and face the ceiling wall 2a are integrally formed on both sides in the front-rear direction (Y direction). The case 2 is provided with a pair of inner side walls 2e and 2e that rise upward (Z1 direction) from the center side of the bottom walls 2d and 2d. Further, an inner bottom wall 2f that connects the inner wall 2e and the upper end of the inner wall 2e and that is continuous with the left and right side walls 2b, 2b is integrally formed. This inner bottom wall 2f is a wall portion on the sound generation side.

  The case 2 has an internal space 3 surrounded by a ceiling wall 2a, side walls 2b and 2b, side walls 2c and 2c, bottom walls 2d and 2d, inner side walls 2e and 2e, and an inner bottom wall 2f. The internal space 3 is substantially isolated from the external space, and the sound generation unit 10 is accommodated in the internal space 3.

  The facing member 4 is fixed to the lower surfaces of the bottom walls 2d, 2d of the case 2. The opposing member 4 is plate-shaped and is a metal plate or a synthetic resin plate. The facing member 4 is fixed to the bottom walls 2d, 2d by means such as screwing. Alternatively, the bottom wall 2 d, 2 d may not be provided in the case 2, and the bottom may be open, and the opening at the bottom may be covered with the facing member 4.

  As shown in FIGS. 2 and 3, the facing member 4 faces the lower side (Z2 side) of the inner bottom wall 2f with a distance, and the lower part of the case 2 faces the inner bottom wall 2f. A sound pressure space 5 in which the vertical direction is restricted by the member 4 and the front-rear direction (Y direction) is restricted by the inner wall 2e and the inner wall 2e is formed. As shown in FIGS. 1 and 2, sound generation windows 6, 6 that open the sound pressure space 5 to the external space are opened below the side walls 2 b, 2 b of the case 2.

  As shown in FIG. 2, the sound generation unit 10 has a magnetic drive unit 11 housed in the internal space 3 of the case 2. The magnetic drive unit 11 has a central yoke 12 made of a magnetic material, a peripheral yoke 13 also made of a magnetic material, and a magnet 14 sandwiched between the central yoke 12 and the peripheral yoke 13. ing.

  A support frame 15 made of metal or synthetic resin is fixed to the lower side (Z2 side) of the surrounding yoke 13. The support frame 15 has a shape that is recessed upward (Z1 direction), and the vibration portion 16 is supported by the support frame 15. The vibration part 16 has a conical cone 16a and a cap 16b attached to the center of the cone 16a. The cap 16b has a protruding shape toward the lower side.

  The outer peripheral portion of the cone 16 a is supported by the outer peripheral portion of the support frame 15 via the outer peripheral damper 17, and the inner peripheral portion of the cone 16 a is supported by the support frame 15 via the inner peripheral damper 18. Along with the deformation of the outer peripheral damper 17 and the inner peripheral damper 18, the cone 16a and the cap 16b are supported so as to vibrate in the vertical direction (Z1-Z2 direction).

  A cylindrical bobbin 19 extending upward (in the Z1 direction) is joined to the inner peripheral portion of the cone 16a, and a voice coil 19a is supported on the bobbin 19. The voice coil 19a is located in a magnetic gap where the central yoke 12 and the peripheral yoke 13 are opposed to each other.

  A circular opening 2g is cut out in the inner bottom wall 2f of the case 2. A mounting piece 15a is integrally formed on the outer peripheral portion of the support frame 15 of the sounding unit 10, and this mounting piece 15a is fixed to the lower surface of the inner bottom wall 2f on the outer peripheral side of the opening 2g. As a result, the vibration part 16 of the sound generation unit 10 appears inside the opening 2g of the inner bottom wall 2f, and this vibration part 16 faces the sound pressure space 5.

  Inside the sound pressure space 5, a cushioning material 21 is fixed to the surface facing the upper side (Z1 side) of the facing member 4. In the embodiment shown in FIGS. 2 and 3, the buffer material 21 is a plate material having a constant thickness, and the surface 21 a facing the vibrating portion 16 is a flat surface. The outer edge 21b of the buffer material 21 is circular. The diameter D1 of the outer edge 21b is smaller than the diameter of the cone 16a of the vibration part 16, and the outer edge 21b is located inside the outer edge of the cone 16a. Therefore, when the vibration part 16 vibrates up and down, the outer periphery damper 17 can be prevented from hitting the buffer material 21.

  At the center of the cushioning material 21, a hole 21c that penetrates the cushioning material 21 up and down is formed. The hole 21c faces the most protruding portion of the cap 16b provided in the vibrating portion 16, and the cap 16b is less likely to hit the cushioning material 21 when the vibrating portion 16 vibrates up and down.

  The thickness T of the cushioning material 21 is set so that the surface 21a of the cushioning material 21 does not hit the vibrating portion 16 when the vibrating portion 16 vibrates downward (Z2 direction) with the maximum amplitude. Yes.

  The buffer material 21 is elastically deformed following the vibration of the air generated in the sound pressure space 5 by the vibration of the vibration part 16 and can consume the vibration as an internal loss, and is formed of a foam material. Foam material is preferably foam rubber, and ethylene propylene rubber or silicon rubber is used.

Specifically, a foam material having a mixture of closed cells and open cells in the internal bubbles is used for the ethylene propylene rubber (EPDM rubber) of the product name “Epto Sealer” manufactured by Nitto Denko Corporation. The foamed material preferably has a hardness of 5.0 (N / cm ² ) or less when a test piece having a size of 10 × 10 mm is compressed at a compression rate of 25%, more preferably 3. 0 (N / cm ² ) or less.

  The speaker device 1 is installed in a vehicle or the like with the facing member 4 facing downward. Since the front of the vibration part 16 of the sounding unit 10 is covered with the facing member 4, it is possible to avoid foreign matter from hitting the vibration part 16.

  The speaker device 1 is used for bass, and the vibration portion 16 vibrates with a relatively large amplitude at a frequency of 100 Hz or less in the vertical direction (Z1-Z2 direction) due to a current applied to the voice coil 19a. Due to this vibration, sound pressure is generated in the sound pressure space 5, and air vibrations are directed in the X direction by the facing member 4 and output from the sound generation window 6 to the outside. Since the sound pressure space 5 surrounded by the inner bottom wall 2f, the inner side walls 2e, 2e, and the facing member 4 is formed in front of the vibration part 16, the bass effect can be increased.

  When the vibration part 16 vibrates greatly in the vertical direction, a sound pressure of a change in air pressure is generated in the sound pressure space 5, and an air flow is generated in the sound pressure space 5 along with the movement of the vibration part 16, The air strikes the facing member 4 and flows toward the sound generation window 6. The air flow at this time tends to generate air noise having a frequency higher than the original sound pressure. However, since the shock absorbing material 21 is provided in the sound pressure space 5 and this shock absorbing material 21 faces the vibrating portion 16, the shock absorbing material 21 follows the movement of air generated inside the sound pressure space 5. It is elastically deformed and its energy is digested as an internal loss of the buffer material 21. For this reason, vibration of relatively high frequency air generated by the air flow is suppressed, air noise is reduced, and low tone sound quality can be improved.

  FIG. 5 shows a measurement result obtained by placing a microphone in the sound generation window 6 to detect sound pressure and performing frequency analysis. The horizontal axis represents frequency (Hz) and the vertical axis represents sound pressure intensity (dB). The vibration unit 16 is driven at a relatively low fundamental frequency of 42 Hz. In the frequency analysis of FIG. 5, harmonics are detected in addition to the fundamental frequency 42 Hz. Of the sound pressure peaks at the fundamental frequency and the harmonic frequency, (i) is the sound pressure peak in the speaker device in which the buffer material 21 is installed, and (ii) is using the buffer material 21. There is no sound pressure peak in the speaker device.

  In FIG. 5, the waveforms of (iii) and (iv) are noise components called noise floors, and (iii) indicates the level of the noise floor of the speaker device on which the buffer material 21 is installed, and (iv) ) Shows the noise floor level of the speaker device not using the buffer material 21.

  When the cushioning material 21 is used, the sound pressure level at both the peak level and the noise floor is lowered in the harmonics, instead of almost lowering the sound pressure level of 42 Hz originally intended to be obtained. It can be seen that there is a reduction.

The buffer material 21 used for the measurement is an ethylene propylene rubber (EPDM rubber) of the product name “Epto Sealer” manufactured by Nitto Denko Corporation, and is a foam material in which closed cells and open cells are mixed in the internal cells. A test piece having a hardness of 1.8 to 2.0 (N / cm ² ) required when a test piece having a size of 10 × 10 mm was compressed at a compression rate of 25% was used. The shape of the buffer material 21 is as shown in FIG. 2 and FIG. 3, and the thickness T is 5 mm, the diameter D1 of the outer edge 21b is 95 mm, the diameter D2 of the hole 21c is 15 mm, and the surface 21a of the buffer material 21 The distance in the Z direction from the outer peripheral edge of the cone 16a was 10 mm.

FIG. 4 shows a modification of the speaker device.
In the speaker device 1A shown in FIG. 4A, a recess 21d that is recessed from the surface thereof toward the opposing member 4 is formed at the center of the buffer material 21A. The concave portion 21d faces the central portion of the downward projecting portion of the cap 16b of the vibration portion 16, so that the cap 16b and the cushioning material 21A are less likely to hit when the vibration portion 16 vibrates.

  In the speaker device 1B shown in FIG. 4B, the surface 21e of the cushioning material 21B has a concave curved surface shape so as to follow the protruding shape of the cap 16b. In the speaker device 1C shown in FIG. 4C, the surface 21f of the cushioning material 21C has a protruding surface so as to follow both the protruding shape of the cap 16b and the recessed shape of the cone 16a.

  As shown in FIG. 4B and FIG. 4C, when the surfaces 21e and 21f of the cushioning material are concave portions or convex portions including inclined surfaces that follow the surface shape of the vibrating portion 16 of the sound generation unit 10. This makes it easy to prevent the vibration portion 16 that vibrates with a large amplitude at a low frequency from hitting the buffer material, and makes the vibration device 16 and the opposing member 4 closer to each other, thereby making it easier to configure the speaker device thin. Moreover, since the air wave by vibration of the vibration part 16 can be received in the wide area of the surface of a buffer material, a buffer effect becomes high and it becomes easy to further reduce air noise.

1, 1A, 1B, 1C Speaker device 2 Case 3 Internal space 4 Opposing member 5 Sound pressure space 6 Sound generation window 10 Sound generation unit 11 Magnetic drive unit 15 Support frame 16 Vibration unit 16a Cone 16b Caps 21, 21A, 21B, 21C Buffer material 21a, 21e, 21f Surface 21c Hole 21d Recess

Claims (5)

A sound generation unit having a magnetic drive unit and a vibration unit vibrated by the magnetic drive unit, and a case having an internal space for housing the sound generation unit are provided, and the vibration unit is provided on a wall portion on the sound generation side of the case In the exposed speaker device,
A facing member facing the vibrating portion at a certain distance from the wall portion on the sound generation side of the case is provided, and a space between the wall portion and the facing member opens toward the side of the case. And
A low-frequency loudspeaker device, wherein a cushioning material formed of a foam material is disposed on a surface of the facing member facing the vibrating portion with a space from the vibrating portion.   2. The bass speaker device according to claim 1, wherein a distance between the surface of the buffer material and the surface of the vibration part is longer than a maximum amplitude of the vibration part toward the space.   3. The low-frequency speaker device according to claim 1, wherein an outer edge of the cushioning material is circular, and the outer edge of the cushioning material is located closer to the center of the vibrating part than the outer edge of the vibrating part.   4. The low-frequency speaker device according to claim 1, wherein an outer edge of the cushioning material is circular, and a concave portion that is recessed toward the hole or the facing member is formed at a central portion of the cushioning material. .   5. The low-frequency speaker device according to claim 1, wherein a surface of the buffer material facing the vibration part has an inclined surface inclined in the same direction as the shape of the surface of the vibration part.

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