Vehicle-mounted speaker

Abstract

The invention provides an in-vehicle speaker capable of expanding a use frequency band to a low range by providing a duct portion in a housing, and further capable of suppressing a decrease in sensitivity of the low range by suppressing a load energy of an air flow in the duct portion. A part of the sound pressure space (Sv) inside the housing (10) serves as a duct section (D). When the duct portion (D) is divided into a plurality of sections from a start end (30E), which is an end portion of the vibration portion, to the sound pressure hole (13), the inner volume of a start end-side section (N1) including the start end (30E) is larger than the inner volume of a sound pressure hole-side section (N2) including the sound pressure hole (13). In addition, the cross-sectional area of the duct section (D) at the starting end (30E) is larger than the opening area of the sound pressure hole (13).

Description

Technical Field

[0001] The present invention relates to a vehicle-mounted speaker, wherein a sound pressure space partitioned by a vibrating portion is formed in a housing, and a sound pressure hole is formed in the housing for communicating the sound pressure space with the outside of the housing. Background Art

[0002] Patent Documents 1 and 2 describe vehicle-mounted speakers used as so-called subwoofers. These vehicle-mounted speakers have a sound-producing unit comprised of a vibration plate and a magnetic drive unit installed within a housing. A duct is integrally formed within the housing to guide the sound pressure generated by the vibration plate to the exterior of the housing, with a sound-producing port opening at the duct's opening. The housing with the vibration plate is installed in the exterior space of the vehicle, and the duct is installed in a hole provided in the vehicle's bulkhead. The sound pressure generated within the housing by the vibration of the vibration plate is transmitted as reproduced sound from the duct's sound-producing port to the interior space of the vehicle.

[0003] The duct of the vehicle-mounted speaker described in Patent Document 1 has a rectangular cross-section, with a uniform cross-sectional area along its entire length. The duct of the vehicle-mounted speaker described in Patent Document 2 has a so-called constricted shape, with the cross-sectional area gradually decreasing midway toward the sound outlet and then gradually increasing toward the sound outlet.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-118585

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-125962 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] The in-vehicle speakers described in Patent Documents 1 and 2 house a sound unit consisting of a diaphragm and a magnetic drive unit within a housing. The sound pressure from the diaphragm's vibration acts on the housing. Because the housing includes a duct, the mass of the air within the duct acts as a load on the diaphragm's vibration. This lowers the lowest resonant frequency f0 of the diaphragm, equivalent to a situation where the mass of the diaphragm is increased. Consequently, when the sound unit is driven within the housing with the duct, the reproduction frequency band can be expanded toward the low frequency range compared to when the sound unit is operated without the duct. On the other hand, when the diaphragm is in operation, the air flow within the duct increases the load energy. Therefore, the duct reduces the reproduction sensitivity in the low frequency range, making it easier to suppress the sound pressure in the low frequency range. In this type of speaker, the design of the housing and duct requires a balance between the conflicting properties of expanding the reproduction frequency toward the low frequency range and reducing the sensitivity in the low frequency range.

[0010] The sound-producing opening of the pipe provided in the vehicle-mounted speaker needs to match the hole portion formed in the partition wall that separates the interior space of the vehicle and the exterior space of the vehicle. However, since there is a limit to increasing the hole portion of the partition wall, the opening area of the sound-producing opening of the pipe cannot be made too large. The vehicle-mounted speaker described in Patent Document 1 is a pipe having a uniform cross-sectional area along its length. Therefore, if the opening area of the sound-producing opening of the pipe is matched with the hole portion of the vehicle's partition wall, the cross-sectional area at each position of the pipe becomes smaller, and the integral value of the cross-sectional area of the entire pipe also becomes smaller. Therefore, the load on the air when it moves in the pipe increases, and the sensitivity is easily reduced in the bass range of the reproduction frequency. The shape of the pipe in the vehicle-mounted speaker described in Patent Document 2 is a necked shape in which the cross-sectional area becomes smaller midway toward the sound-producing opening. Therefore, in this pipe shape, the load on the air when it moves in the pipe also becomes larger, making it difficult to improve the sensitivity in the bass range.

[0011] The present invention has been made to solve the above-mentioned conventional problems, and its object is to provide a vehicle-mounted speaker having a structure that easily achieves a balanced effect of expanding the reproduction frequency band to the low frequency range and improving the sensitivity in the low frequency range without making the opening area of the sound pressure hole formed in the duct too large.

[0012] Means for solving problems

[0013] The present invention is characterized in that, in a vehicle-mounted speaker, a vibration part and a magnetic drive part that drives the vibration part are housed inside a shell in which a sound pressure hole is formed, and a sound pressure space separated by the vibration part and connected to the sound pressure hole is formed inside the shell. In the sound pressure space, a duct part is formed from the end of the vibration part closest to the sound pressure hole as the starting end to the sound pressure hole, and the cross-sectional area of the space of the duct part at the starting end is larger than the opening area of the sound pressure hole.

[0014] The vehicle-mounted speaker of the present invention can be configured such that, when the duct portion is divided into a plurality of sections by equally dividing the distance from the starting end to the sound pressure hole, the internal volume of the starting end side section including the starting end is larger than the internal volume of the sound pressure hole side section including the sound pressure hole.

[0015] For example, when the duct portion is divided into two sections by bisecting the distance from the starting end to the sound pressure hole, the internal volume of the starting end side section including the starting end is larger than the internal volume of the sound pressure hole side section including the sound pressure hole.

[0016] Alternatively, when the pipe portion is divided into three partitions by dividing the distance from the starting end to the sound pressure hole into three equal parts, the internal volume of the starting end side partition including the starting end is larger than either the internal volume of the sound pressure hole side partition including the sound pressure hole or the internal volume of the middle partition.

[0017] In the vehicle-mounted speaker of the present invention, it is preferable that a cross-sectional area of the internal space of the duct portion gradually decreases from the starting end toward the sound pressure hole.

[0018] In addition, the present invention is characterized in that, in a vehicle-mounted speaker, a vibration part and a magnetic drive part that drives the vibration part are accommodated inside a shell in which a sound pressure hole is formed, and a sound pressure space separated by the vibration part and connected to the sound pressure hole is formed inside the shell. When an imaginary line passing through the center of the vibration part and extending along the vibration direction of the vibration part is taken as the vibration center line, and a line perpendicular to the vibration center line and extending to the opening center of the sound pressure hole is taken as the plane center line, the width dimension of the shell in a direction orthogonal to both the vibration center line and the plane center line gradually decreases from the position of the vibration center line toward the sound pressure hole.

[0019] In the vehicle-mounted speaker of the present invention, preferably, the height of the housing when projected onto a vertical plane parallel to both the vibration center line and the plane center line gradually decreases from the position of the vibration center line toward the sound pressure hole.

[0020] Effects of the Invention

[0021] The vehicle-mounted speaker of the present invention easily achieves both the effect of expanding the reproduction frequency into the low frequency range and the effect of improving sensitivity in the low frequency range, even if the cross-sectional area and internal volume near the sound pressure port of the duct are small. By increasing the cross-sectional area and internal volume near the starting end of the duct, i.e., the position inside the housing, the vehicle-mounted speaker of the present invention easily achieves both the effect of expanding the reproduction frequency into the low frequency range and the effect of improving sensitivity in the low frequency range. Furthermore, the shape of the housing when viewed in a planar or vertical plane is large at the center of the vibrating portion and gradually decreases toward the sound pressure port. This easily achieves both the effect of expanding the reproduction frequency into the low frequency range and the effect of improving sensitivity in the low frequency range. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a plan view of a vehicle-mounted speaker according to an embodiment of the present invention.

[0023] Figure 2 It is a side view of the vehicle-mounted speaker according to the embodiment of the present invention.

[0024] Figure 3 This is a perspective view including a partial cross section of the vehicle-mounted speaker according to the embodiment of the present invention.

[0025] Figure 4 It is a planar cross-sectional view of a vehicle-mounted speaker according to an embodiment of the present invention.

[0026] Figure 5 yes Figure 4 An enlarged view of a portion of the planar cross-sectional view is shown.

[0027] Figure 6 yes Figure 2 An enlarged view of a portion of the side view is shown.

[0028] Figure 7 (A) is a planar cross-sectional view showing a first modified example of the vehicle-mounted speaker of the present invention, and (B) is a longitudinal cross-sectional view thereof.

[0029] Figure 8 (A) is a planar cross-sectional view showing a second modified example of the vehicle-mounted speaker of the present invention, and (B) is a longitudinal cross-sectional view thereof.

[0030] Figure 9 This is a graph for explaining the frequency characteristics of the vehicle-mounted speaker according to the embodiment of the present invention.

[0031] Explanation of symbols

[0032] 1,101,201 Car speakers

[0033] 2Next Door

[0034] 10 shell

[0035] 12 openings

[0036] 13 sound pressure holes

[0037] 30 vibration part

[0038] 30E start

[0039] 31 vibration plate

[0040] 32 edge components

[0041] 34 voice coil (magnetic drive unit)

[0042] 36, 37 damping components

[0043] 40 Magnetic circuit unit (magnetic drive unit)

[0044] As, Ao, Ah cross-sectional areas

[0045] D Pipeline Department

[0046] Ds, Do, Dh cross section

[0047] N1, Na starting side partition

[0048] N2, Nc sound pressure hole side partition

[0049] Nb middle partition

[0050] Oh horizontal centerline

[0051] Ov vibration center line

[0052] Ox pipeline centerline

[0053] P Sound pressure acting part

[0054] S1 interior space

[0055] S2 car outdoor space

[0056] Sv sound pressure space DETAILED DESCRIPTION

[0057] (Structure of Vehicle-mounted Speaker 1)

[0058] Figures 1 to 6 A vehicle-mounted speaker 1 according to an embodiment of the present invention is shown. Figure 2 The figure shows a partition wall 2 of a vehicle such as a car, and a hole portion 3 is opened in the partition wall 2. Across the partition wall 2, one space is the vehicle interior space S1 connected to the passenger compartment of the vehicle, and the other space is the vehicle exterior space S2 connected to the space outside the vehicle. The vehicle-mounted speaker 1 is set in the vehicle interior space S1, and the sound when the vibration plate vibrates is given to the vehicle interior space S1. The sound pressure hole 13 of the duct portion formed in the shell 10 of the vehicle-mounted speaker 1 is connected to the hole portion 3, and the sound pressure space in the shell is connected to the vehicle exterior space S2. In addition, it can also be connected to Figure 2 In contrast, the vehicle-mounted speaker 1 is installed in the vehicle interior space S2, and the sound pressure port 13 of the duct portion is connected to the hole portion 3. In this installation example, the sound pressure space in the housing communicates with the vehicle interior space S1 via the duct portion, and the sound pressure port 13 of the duct portion functions as a sound output port for delivering sound to the vehicle interior space S1.

[0059] like Figure 3As shown, the vehicle-mounted speaker 1 has a vibration plate 31 constituting a vibration portion 30 within a housing. An imaginary line extending through the center of the vibration plate 31 and along the vibration direction of the vibration plate 31 is the vibration center line Ov. The Z1-Z2 direction is a vertical direction parallel to the vibration center line Ov, with the Z1 direction being the upward direction and the Z2 direction being the downward direction. Furthermore, the Z2 direction is the sound direction when the vibration plate 31 vibrates. Figure 4 As shown, the line perpendicular to the vibration centerline Ov and extending to the center of the opening of the sound pressure port 13 of the housing 10 is the plane centerline Oh. The X1-X2 direction is the longitudinal direction parallel to the plane centerline Oh. The X1 direction is the interior direction of the housing, and the X2 direction is the direction of sound pressure discharge from the duct. The Y1-Y2 direction is the width direction perpendicular to both the vibration centerline Ov and the plane centerline Oh. Figure 1 and Figure 4 These are a plan view and a plan cross-sectional view of the vehicle-mounted speaker 1 projected onto a plane (XY plane) perpendicular to the vibration center line Ov. Figure 2 This is a side view of the vehicle-mounted speaker 1 projected onto a vertical plane (XZ plane) parallel to both the vibration center line Ov and the plane center line Oh.

[0060] Figure 3 The internal structure of the vehicle-mounted speaker 1 is shown. The vehicle-mounted speaker 1 has a housing 10. The housing 10 is die-cast from a metal material or injection-molded using reinforced plastic. A roughly circular opening 12 is formed on the bottom 11 of the housing 10 facing downward (Z2 direction). The housing 10 is provided with an upper frame 21 and a lower frame 25 that are opposite to the opening 12. The outer periphery 22 of the upper frame 21 and the outer periphery 26 of the lower frame 25 overlap with each other in the vertical direction, and are screwed and fixed to the lower side of the bottom 11 of the housing 10 around the opening 12. A plurality of windows 23 are opened in the upper frame 21, and a plurality of windows 27 are also opened in the lower frame 25.

[0061] like Figure 3 As shown, a vibrating portion 30 is provided inside the housing 10 at a position opposite to the opening 12. The vibrating portion 30 is mainly composed of a conical vibrating plate 31 that contributes to the generation of sound pressure and an edge member 32 that is joined to the outer periphery of the vibrating plate 31. The edge member 32 has a semicircular cross-section and a ring-shaped shape when projected onto a plane. The inner periphery 32a of the edge member 32 is bonded and fixed to the outer periphery 31a of the vibrating plate 31, and the outer periphery 32b of the edge member 32 is sandwiched between the outer periphery 22 of the upper frame 21 and the outer periphery 26 of the lower frame 25, and is fixed to the portion surrounding the opening 12 of the housing 10.

[0062] like Figure 3As shown, a center hole 31b is formed in the center of the conical diaphragm 31, and a cylindrical bobbin 33 is fixed inside the center hole 31b. A voice coil 34 is wound around and fixed to the outer periphery of the lower portion of the bobbin 33. The upper opening of the bobbin 33 is closed by a cover 35. Damping components 36 and 37 are provided inside the housing 10. Each damping component 36 and 37 has a circular shape when projected onto a plane and a corrugated cross-section. The outer peripheries of the damping components 36 and 37 are bonded and fixed to the upper end support portion 24 of the upper frame 21, while the inner peripheries of the damping components 36 and 37 are bonded and fixed to the outer periphery of the bobbin 33. The diaphragm 31 is supported by the edge component 32 and the damping components 36 and 37, and can vibrate vertically along the vibration centerline Ov through the elastic deformation of the edge component 32 and the damping components 36 and 37.

[0063] like Figure 3 As shown, a magnetic circuit unit 40 is supported by the center portion 28 of the lower frame 21. The magnetic circuit unit 40 includes a lower yoke 41 having a center post 41a formed of a magnetic metal material; an annular magnet 42 fixed to the outer periphery of the lower yoke 41; and an annular upper yoke 43 formed of a magnetic metal material and fixed to the upper surface of the magnet 42. The upper surface of the upper yoke 43 is fixed to the lower surface of the center portion 28 of the lower frame 21. A magnetic gap G is formed between the outer periphery of the center post 41a of the lower yoke 41 and the inner periphery of the upper yoke 43. The voice coil 34, which is disposed on the lower outer periphery of the bobbin 33, is located within the magnetic gap G.

[0064] In magnetic circuit portion 40 , a magnetic flux is formed that traverses magnetic gap G. The electromagnetic force generated by the voice coil current flowing through voice coil 34 within magnetic gap G and the magnetic flux traversing voice coil 34 within magnetic gap G imparts a vertical vibration force to vibrating portion 30 via voice coil 34 . Magnetic circuit portion 40 and voice coil 34 constitute a "magnetic drive unit."

[0065] The opening 12 opened at the bottom 11 of the housing 10 is blocked by the vibration part 30 composed of the vibration plate 31 and the edge member 32 and the cover 35 covering the upper part of the bobbin 33. Figure 4 As shown, a sound pressure hole 13 opening in the X2 direction is provided in the housing 10. The interior of the housing 10 is formed into a sound pressure space Sv that is substantially completely separated by the vibrating portion 30 and the cover 35 that block the opening 12. The sound pressure space Sv is connected to the space outside the housing 10 only through the sound pressure hole 13.

[0066] like Figure 2As shown, the housing 10 of the vehicle-mounted speaker 1 is installed in the vehicle interior space S1, and the sound pressure hole 13 is fixed inside the hole 3 formed in the partition wall 2. When the diaphragm 31 vibrates, the resulting sound pressure acts on the vehicle interior space S1 through the multiple windows 27 formed in the lower frame 21, providing reproduced sound in the vehicle interior space S1. When the diaphragm 31 vibrates, a back pressure with an opposite phase to the sound pressure acting on the vehicle interior space S1 acts on the sound pressure space Sv within the housing 10. This back pressure is then transmitted to the vehicle exterior space S2 via the sound pressure hole 13.

[0067] (Shape of Sound Pressure Space Sv)

[0068] exist Figure 4 FIG. 1 shows a plane cross section of the internal structure of the sound pressure space Sv inside the housing 10 projected onto a plane (XY plane) perpendicular to the vibration center line Ov. The plane area of the sound pressure space Sv onto which the vibration part 30 composed of the vibration plate 31 and the edge member 32 is projected is the sound pressure action part P that directly receives the air pressure generated by the vibration of the vibration part 30. The area outside the sound pressure action part P in the sound pressure space Sv, i.e., Figure 5 The dotted line area Sd in FIG is an area where the air pressure acting on the sound pressure acting portion P is guided to the sound pressure hole 13. Figure 5 In the region Sd indicated by the dotted line, the end of the vibrating portion 30 closest to the sound pressure hole 13 is referred to as the start end 30E, and the region from the start end 30E to the sound pressure hole 13 is referred to as the duct portion D.

[0069] like Figure 4 As shown, the width dimension of the shell 10 in the Y1-Y2 direction, which is orthogonal to both the vibration center line Ov and the plane center line Oh, gradually decreases from the position of the vibration center line Ov toward the opening center of the sound pressure hole 13. The width dimension Wo at the vibration center line Ov of the sound pressure space Sv inside the shell 10 is the largest, and the width dimension We at the opening center of the sound pressure hole 13 is the smallest. From the largest width dimension Wo to the smallest width dimension We, the size gradually decreases in the manner of a linear function. In addition, the size may also gradually decrease in the manner of a quadratic function from the largest width dimension Wo to the smallest width dimension We. As shown in FIG. Figure 2 As shown, the height dimension of the shell 10 when projected onto a vertical plane parallel to both the vibration center line Ov and the plane center line Oh is the largest Ho at the position of the vibration center line Ov, and is the smallest He at the position of the opening center of the sound pressure hole. The shell 10 gradually decreases from the largest height dimension Ho to the smallest height dimension He.

[0070] exist Figure 5 and Figure 6In the duct portion D, which forms part of the sound pressure space Sv, the cross section passing through the start end 30E is denoted by Ds, and the cross section passing through the center of the opening of the sound pressure hole 13 is denoted by Do. Furthermore, the intermediate cross section, which bisects the distance in the X direction from cross section Ds to cross section Do, is denoted by Dh. The cross-sectional area of the internal space of duct portion D at cross section Ds is As, the cross-sectional area of the internal space of duct portion D at intermediate cross section Dh is Ah, and the cross-sectional area of the internal space of duct portion D at cross section Do is Ao.

[0071] like Figure 6 As shown, the portion of the housing 10 forming the duct portion D is slightly curved downward toward the sound pressure hole 13. The cross-sectional areas As, Ah, and Ao are Figure 6 The vertical cross-sectional area within the duct portion D at each of the positions Ps, Ph, and Po shown. Specifically, when an imaginary line passing through the center of any of a plurality of cross-sections arranged in the X direction is taken as the duct centerline Ox, each of the cross-sectional areas Ds, Dh, and Do is a plane perpendicularly intersecting the tangent to the duct centerline Ox, and the cross-sectional areas As, Ah, and Ao are the cross-sectional areas of the plane perpendicularly intersecting the tangent to the duct centerline Ox. Alternatively, the cross-sectional areas As, Ah, and Ao are the cross-sectional areas of the cross-sectional area with the smallest cross-sectional area among the multiple cross-sectional areas passing through the positions Ps, Ph, and Po. Furthermore, a dust-proof grille 15 is provided on the sound pressure hole 13. Alternatively, a porous plate or mesh may also be provided. The cross-sectional area Ao of the cross-sectional area Do passing through the center of the opening of the sound pressure hole 13 is the cross-sectional area assuming the absence of the grille 15, porous plate, or mesh, and is the opening area of the sound pressure hole 13.

[0072] The shape of the interior space of the duct portion D, which forms part of the sound pressure space Sv, is such that the cross-sectional area As of the interior space of the duct portion D at the section Ds passing through the starting end 30E is larger than the cross-sectional area Ao of the interior space at the section Do passing through the center of the opening of the sound pressure hole 13. The cross-sectional area Ah of the interior space at the intermediate section Dh is smaller than the cross-sectional area As but larger than the cross-sectional area Ao. The cross-sectional area Ao of the duct portion D is the smallest and increases in the order of Ah and As (As>Ah>Ao). The cross-sectional area of the interior space of the duct portion D gradually decreases from the cross-sectional area As to the cross-sectional area Ao.

[0073] like Figure 5 and Figure 6 As shown, when the interior of the duct portion D is divided from the cross section Ds to the middle cross section Dh into a starting end side partition N1 including the starting end 30E, and from the middle cross section Dh to the cross section Do into a sound pressure hole side partition N2 including the sound pressure hole 13, the internal volume of the starting end side partition N1 is larger than the internal volume of the sound pressure hole side partition N2. Figure 5As shown, when the interior of the duct portion D is divided into three equal sections along the X-direction distance, namely, a starting-end section Na including the starting end 30E, a sound pressure port side section Nc including the sound pressure port 13, and a middle section Nb, the internal volume of the starting-end section Na is greater than either the internal volume of the sound pressure port side section Nc or the internal volume of the middle section Nb. Furthermore, the internal volume decreases in the order of the starting-end section Na, middle section Nb, and sound pressure port side section Nc. In other words, when the X-direction distance from the starting end 30E to the opening center of the sound pressure port 13 is divided into a plurality of equal sections, the internal volume of the starting-end section including the starting end 30E is greater than the internal volume of the sound pressure port side section including the sound pressure port 13.

[0074] (Sound Effects)

[0075] The sound pressure space Sv, which is the interior space of the housing 10, includes a region Sd marked with a dotted line that guides the air pressure acting on the sound pressure applying portion P toward the sound pressure hole 13. This region Sd is aligned with the sound pressure applying portion P, which directly receives the air pressure generated by the vibration of the vibrating portion 30. A portion of this region Sd forms the duct portion D. The mass of the air within this region Sd and the duct portion D constitutes the load mass when the vibrating portion 30 is operated. This is equivalent to an increase in the mass of the vibrating portion 30, as a characteristic of the reproducing unit composed of the vibrating portion 30 and the magnetic circuit portion 40. Consequently, the minimum resonant frequency f0 of the vibrating portion is lowered, enabling the reproduction frequency to be extended to the low frequency range.

[0076] The housing 10 and the duct portion D have the following features.

[0077] (a) The width Wo of the sound pressure space Sv within the housing 10 is largest at the center line Ov, and the width We is smallest at the center of the opening of the sound pressure port 13. The widths gradually decrease from the largest width Wo to the smallest width We. The height of the housing 10 gradually decreases from the largest height Ho to the smallest height He.

[0078] (b) The cross-sectional area of the pipe portion D is As>Ao, As>Ah>Ao.

[0079] (c) When the duct portion D is divided into a plurality of sections by equally dividing the distance in the X direction from the start end 30E to the sound pressure hole 13 , the internal volume of the start end side section including the start end 30E is larger than the internal volume of the sound pressure hole side section including the sound pressure hole 13 .

[0080] When the vibrating portion 30 vibrates and air flows into the duct portion D, the smaller the cross-section of the duct portion D, the greater the resistance. As the value obtained by integrating the cross-sectional area of each cross-section in the X direction over the entire length of the duct decreases, the load energy of the air flowing throughout the entire area of the duct portion D increases. When the load energy increases, the movement resistance of the vibrating portion 30 increases, the sensitivity of the bass range decreases, and the sound pressure generated in the bass range decreases. Figure 2 The hole 3 of the partition wall 2 shown is determined by the vehicle model, so the size of the opening area of the sound pressure hole 13 is limited. Therefore, in the vehicle-mounted speaker 1 of the embodiment, as shown in (a), (b), and (c), the cross-sectional area and volume of the sound pressure space Sv are set to increase as they move from the sound pressure hole 13 toward the inside of the housing 10. This increases the value obtained by integrating the cross-sectional area of each cross section of the duct portion D along the X direction over the entire duct length. This reduces the load energy during vibration of the vibrating portion 30, improves bass sensitivity, and increases the reproduced sound pressure in the bass range.

[0081] exist Figure 9 The graph shows the simulation results of the frequency characteristics (i) of the vehicle-mounted speaker 1 according to the embodiment of the present invention, the frequency characteristics (ii) of Comparative Example 1, and the frequency characteristics (iii) of Comparative Example 2. The horizontal axis of the graph is the reproduction frequency (Hz), and the vertical axis is the reproduction sound pressure (dB). Comparative Example 1 is a Figure 3 The regenerative unit of the vibration part 30, magnetic circuit part 40 and damping components 36 and 37 shown in the figure is not housed in the housing 10, but is only fixed to the baffle to operate. Figure 1 and Figure 2 In the housing 10 shown, the cross-sectional area of the internal space of the duct portion D is made uniform over the entire length without changing due to the opening area of the sound pressure hole 13 , and the speaker operates as an example.

[0082] according to Figure 9 The simulation results shown show that, compared to the frequency characteristic (ii) of Comparative Example 1, in which the regeneration unit is mounted on a baffle, the frequency characteristic (i) of the vehicle-mounted speaker 1 with a duct portion and the frequency characteristic (iii) of Comparative Example 2 can expand the regeneration frequency band to the usable frequency band F of a woofer, for example, below 100 Hz. Furthermore, the frequency characteristic (i) of the vehicle-mounted speaker 1 according to the embodiment shows improved sensitivity in the bass range of the usable frequency band F, compared to the frequency characteristic (iii) of Comparative Example 2, which has a duct portion with a uniform cross-sectional area.

[0083] (Variation)

[0084] exist Figure 7In the first modified example of the vehicle-mounted speaker 101, as shown in (A), the planar shape of the duct portion D has a constant width from the starting end 30E to the middle, and then the width becomes smaller until it reaches the sound pressure hole 13. As shown in (B), in the side view, the height of the duct portion D is uniform. The internal volume of the starting end side section N1 of the duct portion D is larger than the internal volume of the sound pressure hole side section N2. Figure 8 In the second modified example of the vehicle-mounted speaker 201, as shown in (A), the planar shape of the duct portion D has a constant width along its entire length from the starting end 30E to the sound pressure port 13. As shown in (B), in its side profile, the height of the duct portion D is higher from the starting end 30E to midway, then gradually decreases, becoming smaller near the sound pressure port 13. In the second modified example, the internal volume of the starting end-side subsection N1 of the duct portion D is also greater than the internal volume of the sound pressure port-side subsection N2.

[0085] In the vehicle-mounted speaker 101 of the first modification and the vehicle-mounted speaker 201 of the second modification, the internal volume of the starting-end-side subarea N1 of the duct portion D is greater than the internal volume of the sound pressure port-side subarea N2. Furthermore, the cross-sectional area of the internal space of the duct portion D in a section passing through the starting end 30E is larger than the cross-sectional area of the internal space in a section passing through the opening center of the sound pressure port 13. This makes it easier to balance the effects of expanding the usable reproduction frequency band to the low frequency range and improving sensitivity in the low frequency range.

Claims

1. A car-mounted speaker, characterized in that: In the vehicle-mounted speaker, a vibrating portion and a magnetic driving portion that drives the vibrating portion are housed inside a housing having a sound pressure hole formed therein, and a sound pressure space separated by the vibrating portion and communicating with the sound pressure hole is formed within the housing. In the sound pressure space, the duct portion is formed from the end of the vibrating portion closest to the sound pressure hole to the sound pressure hole. A cross-sectional area of the space of the duct portion at the starting end is larger than an opening area of the sound pressure hole.

2. The vehicle-mounted speaker according to claim 1, When the duct portion is divided into a plurality of sections by equally dividing the distance from the starting end to the sound pressure hole, the internal volume of the starting end side section including the starting end is larger than the internal volume of the sound pressure hole side section including the sound pressure hole.

3. The vehicle-mounted speaker according to claim 2, When the duct portion is divided into two sections by bisecting the distance from the starting end to the sound pressure hole, the internal volume of the starting end side section including the starting end is larger than the internal volume of the sound pressure hole side section including the sound pressure hole.

4. The vehicle-mounted speaker according to claim 2, When the duct portion is divided into three sections by dividing the distance from the starting end to the sound pressure hole into three equal parts, the internal volume of the starting end side section including the starting end is larger than either the internal volume of the sound pressure hole side section including the sound pressure hole or the internal volume of the middle section.

5. The vehicle-mounted speaker according to any one of claims 1 to 4, The cross-sectional area of the internal space of the duct portion gradually decreases from the starting end toward the sound pressure hole.

6. A car-mounted speaker, characterized in that: In the vehicle-mounted speaker, a vibrating portion and a magnetic driving portion that drives the vibrating portion are housed inside a housing having a sound pressure hole formed therein, and a sound pressure space separated by the vibrating portion and communicating with the sound pressure hole is formed within the housing. When an imaginary line passing through the center of the vibrating portion and extending in the vibration direction of the vibrating portion is taken as a vibration center line, and a line perpendicularly intersecting the vibration center line and extending to the opening center of the sound pressure hole is taken as a plane center line, The width of the housing in a direction perpendicular to both the vibration center line and the plane center line gradually decreases from the position of the vibration center line toward the sound pressure hole.

7. The vehicle-mounted speaker according to claim 6, The height of the housing when projected onto a vertical plane parallel to both the vibration center line and the plane center line gradually decreases from the position of the vibration center line toward the sound pressure hole.

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