On-vehicle speaker

Abstract

To provide an on-vehicle speaker capable of enlarging a use frequency band to a low frequency band by arranging a duct part in a case, and also capable of suppressing deterioration of sensitivity in the low frequency band by suppressing a load energy of an air flow inside the duct part.SOLUTION: In an on-vehicle speaker 1, a part of a sound pressure space Sv inside a case 10 is defined as a duct part D. When the duct part D is divided into a plurality of sections from a start end 30E being an end of a vibration part to a sound pressure hole 13, an internal space of a start end side section N1 including the start end 30E is larger than an internal space of a sound pressure hole side section N2 including the sound hole 13. A cross-sectional area of the duct part D at the start end 30E is larger than an opening area of the sound pressure hole 13.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an in-vehicle speaker in which a sound pressure space partitioned by a vibrating part is formed inside a case, and a sound pressure hole is formed in the case to communicate the sound pressure space with the outside of the case. [Background technology]

[0002] Patent Documents 1 and 2 describe in-vehicle speakers used as so-called subwoofers, etc. These in-vehicle speakers have a sound-generating unit inside a case, which is comprised of a diaphragm and a magnetic drive unit. The case is integrally formed with a duct that directs sound pressure generated when the diaphragm vibrates to the outside of the case, and the duct has a sound-generating port. The case with the diaphragm is installed in the exterior space of the vehicle, and the duct is attached to a hole in a bulkhead of the vehicle. Sound pressure generated inside the case by vibration of the diaphragm is output as reproduced sound from the sound-generating port of the duct into the interior space of the vehicle.

[0003] The in-vehicle speaker described in Patent Document 1 has a duct with a rectangular cross section, and the duct has a uniform cross-sectional area along its entire length. The in-vehicle speaker duct described in Patent Document 2 has a so-called constricted shape, in which the cross-sectional area gradually decreases halfway toward the sound outlet, and then gradually increases toward the sound outlet. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-118585 [Patent Document 2] Japanese Patent Application Publication No. 2019-125962 Summary of the Invention [Problem to be solved by the invention]

[0005] The car speakers described in Patent Documents 1 and 2 house a sound-generating unit, consisting of a diaphragm and a magnetic drive unit, in a case. When the diaphragm vibrates, sound pressure acts inside the case. Because the case has a duct, the air mass inside the duct acts as a load on the diaphragm. This increases the sound-generating unit's characteristics, equivalent to increasing the mass of the diaphragm, lowering the minimum resonant frequency (f0) of the vibrating unit. Therefore, when the sound-generating unit is operated in a case with a duct, it is possible to expand the playback frequency range toward the low-frequency range compared to when it is operated without a duct. On the other hand, because the airflow inside the duct increases the load energy when the diaphragm moves, the presence of a duct tends to reduce playback sensitivity in the low-frequency range and suppress sound pressure in the low-frequency range. For this type of speaker, the shape of the case and duct must be designed to balance the conflicting characteristics of expanding the playback frequency toward the low-frequency range and reducing sensitivity in the low-frequency range.

[0006] The sound outlet of a duct in an in-vehicle speaker needs to be aligned with a hole formed in the partition separating the interior and exterior spaces of the vehicle. However, due to limitations on how large the hole in the partition can be, the opening area of ​​the duct's sound outlet cannot be made too large. The in-vehicle speaker described in Patent Document 1 has a duct with a uniform cross-sectional area along its length. Therefore, if the opening area of ​​the duct's sound outlet is aligned with the hole in the vehicle's partition, the cross-sectional area at each position on the duct becomes smaller, and the integrated value of the cross-sectional area of ​​the entire duct also becomes smaller. This increases the load on air moving through the duct, which tends to reduce sensitivity in the low-frequency range of the playback frequency. The in-vehicle speaker described in Patent Document 2 has a constricted duct shape in which the cross-sectional area decreases as it approaches the sound outlet. Therefore, even with this duct shape, the load on air moving through the duct becomes larger, making it difficult to improve sensitivity in the low-frequency range.

[0007] The present invention solves the above-mentioned conventional problems, and aims to provide an in-vehicle speaker with a structure that makes it easy to balance the effect of expanding the reproduction frequency band into the low-frequency range and the effect of increasing sensitivity in the low-frequency range, without excessively increasing the opening area of ​​the sound pressure hole formed in the duct. [Means for solving the problem]

[0008] The present invention provides an in-vehicle speaker in which a vibration unit and a magnetic drive unit that drives the vibration unit are housed inside a case having a sound pressure hole formed therein, and a sound pressure space that is partitioned by the vibration unit and communicates with the sound pressure hole is formed inside the case, the sound pressure space is a duct portion extending from an end of the vibration portion closest to the sound pressure hole to the sound pressure hole, The cross-sectional area of ​​the space of the duct portion at the starting end is larger than the opening area of ​​the sound pressure hole.

[0009] The in-vehicle speaker of the present invention can be configured such that when the duct portion is divided into multiple 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.

[0010] For example, when the distance from the starting end to the sound pressure hole is divided into two equal parts to divide the duct portion into two sections, 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.

[0011] Alternatively, when the distance from the starting end to the sound pressure hole is divided into three equal parts to divide the duct portion into three sections, the internal volume of the starting end side section including the starting end is larger than both the internal volume of the sound pressure hole side section including the sound pressure hole and the internal volume of the intermediate section.

[0012] In the in-vehicle speaker of the present invention, it is preferable that the cross-sectional area of ​​the internal space of the duct portion gradually decreases from the starting end toward the sound pressure hole.

[0013] The present invention also provides an in-vehicle speaker in which a vibration section and a magnetic drive section that drives the vibration section are housed inside a case that has a sound pressure hole formed therein, and a sound pressure space that is partitioned by the vibration section and communicates with the sound pressure hole is formed inside the case, When an imaginary line passing through the center of the vibrating part and extending in the vibration direction of the vibrating part is defined as a vibration center line, and a line perpendicular to the vibration center line and extending to the center of the opening of the sound pressure hole is defined as a planar center line, The width of the case in a direction perpendicular to both the vibration center line and the planar center line gradually decreases from the position of the vibration center line toward the sound pressure hole.

[0014] In the in-vehicle speaker of the present invention, it is preferable that the height dimension of the case when projected onto a vertical plane parallel to both the vibration center line and the planar center line gradually decreases from the position of the vibration center line toward the sound pressure hole. [Effects of the Invention]

[0015] In the in-vehicle speaker of the present invention, even if the cross-sectional area and internal volume of the duct near the sound pressure hole are small, by increasing the cross-sectional area and internal volume at the start of the duct, i.e., near the inside position of the case, it becomes easier to achieve 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, in the in-vehicle speaker of the present invention, by making the shape of the case when viewed in a plan view or a vertical view large at the center of the vibrating part and gradually decreasing toward the sound pressure hole, it becomes easier to achieve 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 explanation of the drawings]

[0016] [Figure 1] 1 is a plan view of an in-vehicle speaker according to an embodiment of the present invention; [Figure 2] 1 is a side view of an in-vehicle speaker according to an embodiment of the present invention; [Figure 3] 1 is a perspective view including a partial cross section of an in-vehicle speaker according to an embodiment of the present invention; [Figure 4]1 is a cross-sectional plan view of an in-vehicle speaker according to an embodiment of the present invention; [Figure 5] A partial enlargement of the plan cross section shown in Figure 4; [Figure 6] A partial enlargement of the side view shown in Figure 2; [Figure 7] 1A is a plan cross-sectional view showing a first modified example of the in-vehicle speaker of the present invention, and FIG. 1B is a longitudinal cross-sectional view thereof; [Figure 8] 1A is a plan cross-sectional view showing a second modified example of the in-vehicle speaker of the present invention, and FIG. 1B is a longitudinal cross-sectional view thereof; [Figure 9] 1 is a diagram illustrating the frequency characteristics of an in-vehicle speaker according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0017] <Structure of car speaker 1> 1 to 6 show an in-vehicle speaker 1 according to an embodiment of the present invention. FIG. 2 shows a partition wall 2 of a vehicle such as an automobile, with a hole 3 opening in the partition wall 2. One space across the partition wall 2 is an interior space S1 of the vehicle that communicates with the passenger compartment of the vehicle, and the other space is an exterior space S2 that communicates with a space outside the vehicle. The in-vehicle speaker 1 is installed in the interior space S1, and sound generated when the diaphragm vibrates is imparted to the interior space S1. A sound pressure hole 13 formed in a duct portion of a case 10 of the in-vehicle speaker 1 is connected to the hole 3, and the sound pressure space within the case communicates with the exterior space S2. Note that, contrary to FIG. 2, the in-vehicle speaker 1 may also be installed in the exterior space S2, with the sound pressure hole 13 in the duct portion connected to the hole 3. In this installation example, the sound pressure space inside the case is communicated 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 that provides sound to the vehicle interior space S1.

[0018] As shown in FIG. 3, the car speaker 1 has a diaphragm 31 that constitutes a vibrating section 30 within a case. An imaginary line that passes through the center of the diaphragm 31 and extends in the vibration direction of the diaphragm 31 is the vibration center line Ov. The Z1-Z2 direction is the up-down direction parallel to the vibration center line Ov, with the Z1 direction being the upward direction and the Z2 direction being the downward direction. The Z2 direction is the sound-generating direction when the diaphragm 31 vibrates. As shown in FIG. 4, the plane center line Oh is a line that perpendicularly intersects the vibration center line Ov and extends to the center of the opening of the sound pressure hole 13 in the case 10. The X1-X2 direction is a vertical direction parallel to the plane center line Oh, with the X1 direction toward the interior of the case and the X2 direction being the sound pressure exhaust direction from the duct. The Y1-Y2 direction is a width direction that is perpendicular to both the vibration center line Ov and the plane center line Oh. 1 and 4 are a plan view and a cross-sectional plan view of the car speaker 1 projected onto a plane (XY plane) perpendicular to the vibration center line Ov, and Fig. 2 is a side view of the car speaker 1 projected onto a vertical plane (XZ plane) parallel to both the vibration center line Ov and the planar center line Oh.

[0019] FIG. 3 shows the internal structure of the car speaker 1. The car speaker 1 has a case 10. The case 10 is die-cast from a metal material or injection-molded from reinforced plastic. A substantially circular opening 12 is formed in the bottom 11 of the case 10 facing downward (in the Z2 direction). The case 10 is provided with an upper frame 21 and a lower frame 25 that face the opening 12. An outer periphery 22 of the upper frame 21 and an outer periphery 26 of the lower frame 25 are stacked one above the other and are fixed by screws to the underside of the bottom 11 of the case 10 around the periphery of the opening 12. The upper frame 21 has a plurality of windows 23, and the lower frame 25 also has a plurality of windows 27.

[0020] As shown in FIG. 3, a vibrating section 30 is provided inside the case 10 at a position facing the opening 12. The vibrating section 30 is composed of a cone-shaped diaphragm 31 that mainly contributes to the generation of sound pressure, and an edge member 32 bonded to the outer periphery of the diaphragm 31. The edge member 32 has a semicircular cross section and a ring-like shape when projected onto a plane. An inner periphery 32a of the edge member 32 is bonded and fixed to the outer periphery 31a of the diaphragm 31, and an 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 periphery of the opening 12 of the case 10.

[0021] As shown in FIG. 3 , a central hole 31b is formed in the center of a cone-shaped diaphragm 31, and a cylindrical bobbin 33 is fixed inside the central hole 31b. A voice coil 34 is wound around and fixed to the outer periphery of the lower part of the bobbin 33. The opening at the top of the bobbin 33 is closed with a cap 35. Damper members 36 and 37 are provided inside the case 10. Each of the damper members 36 and 37 has a circular shape when projected onto a plane and a corrugated cross section. The outer peripheries of the damper members 36 and 37 are bonded and fixed to the upper end support portion 24 of the upper frame 21, and the inner peripheries of the damper members 36 and 37 are bonded and fixed to the outer periphery of the bobbin 33. The diaphragm 31 is supported by the edge member 32 and the damper members 36 and 37, and can vibrate up and down along the vibration center line Ov due to elastic deformation of the edge member 32 and the damper members 36 and 37.

[0022] As shown in Fig. 3, a magnetic circuit unit 40 is supported at the center 28 of the lower frame 21. The magnetic circuit unit 40 is composed of a lower yoke 41 having a center pole 41a made of a magnetic metal material, a ring-shaped magnet 42 fixed onto the outer periphery of the lower yoke 41, and a ring-shaped upper yoke 43 made 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 28 of the lower frame 21. A magnetic gap G is formed between the outer periphery of the center pole 41a of the lower yoke 41 and the inner periphery of the upper yoke 43, and a voice coil 34 provided on the lower outer periphery of the bobbin 33 is located inside the magnetic gap G.

[0023] In the magnetic circuit unit 40, a magnetic flux is generated that crosses the magnetic gap G. An electromagnetic force is generated by the voice current flowing through the voice coil 34 located in the magnetic gap G and the magnetic flux that crosses the voice coil 34 in the magnetic gap G, and a vertical vibration force is applied to the vibration unit 30 via the voice coil 34. The magnetic circuit unit 40 and the voice coil 34 constitute a "magnetic drive unit."

[0024] An opening 12 opening into the bottom 11 of the case 10 is closed by a cap 35 that covers the vibrating part 30, which is made up of a diaphragm 31 and an edge member 32, and the top of the bobbin 33. As shown in Figure 4, the case 10 is provided with a sound pressure hole 13 that opens in the X2 direction. The inside of the case 10 is a sound pressure space Sv that is almost completely partitioned by the vibrating part 30 and cap 35 that close the opening 12, and this sound pressure space Sv communicates with the space outside the case 10 only by the sound pressure hole 13.

[0025] 2, the in-vehicle speaker 1 has a case 10 provided in a vehicle interior space S1, and a sound pressure hole 13 fixed inside a hole 3 formed in a partition wall 2. When the diaphragm 31 vibrates, the resulting sound pressure acts on the vehicle interior space S1 through multiple windows 27 formed in the lower frame 21, and reproduced sound is provided to the vehicle interior space S1. When the diaphragm 31 vibrates, a back pressure that is in the opposite phase to the sound pressure acting on the vehicle interior space S1 acts on the sound pressure space Sv within the case 10, and this back pressure is provided to the vehicle exterior space S2 through the sound pressure hole 13.

[0026] <Shape of sound pressure space Sv> 4 shows the internal structure of sound pressure space Sv inside case 10 as a planar cross section projected onto a plane (XY plane) perpendicular to vibration center line Ov. The planar region of sound pressure space Sv onto which vibration section 30, consisting of diaphragm 31 and edge member 32, is projected is sound pressure action section P, which is directly subjected to air pressure due to vibration of vibration section 30. The region of sound pressure space Sv other than sound pressure action section P, i.e., region Sd indicated by a dashed line in FIG. 5, is a region that guides the air pressure acting on sound pressure action section P to sound pressure hole 13. In the following description, within region Sd indicated by a dashed line in FIG. 5, the end of vibration section 30 closest to sound pressure hole 13 is referred to as starting end 30E, and the region from starting end 30E to sound pressure hole 13 is referred to as duct section D.

[0027] As shown in FIG. 4, the width of the case 10 in the Y1-Y2 direction, which is perpendicular 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 center of the opening of the sound pressure hole 13. The sound pressure space Sv inside the case 10 has a width Wo that is largest at the vibration center line Ov and a width We that is smallest at the center of the opening of the sound pressure hole 13, and its size gradually decreases linearly from the maximum width Wo to the minimum width We. Note that the size may also gradually decrease quadratically from the maximum width Wo to the minimum width We. As shown in FIG. 2, the height of the case 10 when projected onto a vertical plane parallel to both the vibration center line Ov and the plane center line Oh is maximum at the position of the vibration center line Ov, Ho, and minimum at the position of the center of the opening of the sound pressure hole, and the case 10 gradually decreases from the maximum height Ho to the minimum height He.

[0028] 5 and 6, in duct portion D, which is part of sound pressure space Sv, a cross section passing through the starting end 30E is indicated by Ds, and a cross section passing through the opening center of sound pressure hole 13 is indicated by Do. Also, an intermediate cross section at a midpoint that bisects the distance in the X direction from cross section Ds to cross section Do is indicated 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.

[0029] As shown in FIG. 6 , the portion of the case 10 that forms the duct portion D curves slightly downward toward the sound pressure hole 13. The cross-sectional areas As, Ah, and Ao are the vertical cross-sectional areas within the duct portion D at the positions Ps, Ph, and Po shown in FIG. 6 . That is, when a virtual line passing through the center of any multiple cross sections aligned in the X direction is defined as a duct center line Ox, the cross sections Ds, Dh, and Do are planes that intersect perpendicularly with a tangent to the duct center line Ox, and the cross-sectional areas As, Ah, and Ao are the cross-sectional areas of the planes that intersect perpendicularly with a tangent to the duct center line Ox. Alternatively, the cross-sectional areas As, Ah, and Ao are the cross-sectional areas of the smallest cross sections among the multiple cross sections that pass through the positions Ps, Ph, and Po. A dust-proof grid 15 is provided in the sound pressure hole 13. Alternatively, a perforated plate or net may be provided. The cross-sectional area Ao of the cross section Do passing through the center of the opening of the sound pressure hole 13 is the cross-sectional area when it is assumed that the grid 15, perforated plate or net does not exist, and the cross-sectional area Ao is the opening area of ​​the sound pressure hole 13.

[0030] The shape of the internal space of the duct portion D, which is part of the sound pressure space Sv, is such that the cross-sectional area As of the internal space of the duct portion D at the cross section Ds passing through the starting end 30E is larger than the cross-sectional area Ao of the internal space at the cross section Do passing through the opening center of the sound pressure hole 13. The cross-sectional area Ah of the internal space at the intermediate cross section Dh is smaller than the cross-sectional area As but larger than the cross-sectional area Ao. The cross-sectional areas of the duct portion D are smallest at Ao, and then Ah, then As (As>Ah>Ao). The cross-sectional area of ​​the internal space of the duct portion D gradually decreases from the cross-sectional area As to the cross-sectional area Ao.

[0031] 5 and 6, when the interior of duct portion D is divided into three equal sections in the X direction, namely, a starting section N1 including starting end 30E from cross section Ds to intermediate cross section Dh, and a sound pressure hole side section N2 including sound pressure hole 13, as shown in FIG. 5 and FIG. 6, the internal volume of starting section N1 is larger than the internal volume of sound pressure hole side section N2. Also, as shown in FIG. 5, when the interior of duct portion D is divided into three equal sections in the X direction, namely, a starting section Na including starting end 30E, a sound pressure hole side section Nc including sound pressure hole 13, and an intermediate section Nb, the internal volume of starting section Na is larger than both the internal volume of sound pressure hole side section Nc and the internal volume of the intermediate section Nb. Furthermore, the internal volumes decrease in the order of the starting section Na, the intermediate section Nb, and the sound pressure hole side section Nc. In other words, when the distance in the X direction from the starting end 30E to the center of the opening of the sound pressure hole 13 is divided into multiple equal parts and the duct section D is divided into multiple sections, the internal volume of the starting end side section including the starting end 30E is larger than the internal volume of the sound pressure hole side section including the sound pressure hole 13.

[0032] <Sound Effects> The sound pressure space Sv, which is the internal space of the case 10, has a sound pressure action part P that is directly subjected to the air pressure caused by the vibration of the vibrating part 30, and an area Sd indicated by a dashed line that directs the air pressure acting on the sound pressure action part P to the sound pressure hole 13, with part of the area Sd forming a duct part D. The mass of the air inside this area Sd and duct part D becomes the load mass when operating the vibrating part 30, and in terms of the characteristics of the playback unit consisting of the vibrating part 30 and magnetic circuit part 40, this is equivalent to an increase in the mass of the vibrating part 30. As a result, the lowest resonance frequency f0 of the vibrating part is lowered, making it possible to extend the playback frequency into the low-frequency range.

[0033] The case 10 and the duct portion D have the following features. (a) The sound pressure space Sv inside the case 10 has a width dimension Wo that is largest at the center line Ov and a width dimension We that is smallest at the center of the opening of the sound pressure hole 13, and its size gradually decreases from the maximum width dimension Wo to the minimum width dimension We. The height dimension of the case 10 gradually decreases from the maximum height dimension Ho to the minimum height dimension He. (b) The cross-sectional area of ​​duct section D is As>Ao and As>Ah>Ao. (c) When the duct section D is divided into multiple sections by equally dividing the distance in the X direction from the starting end 30E to the sound pressure hole 13, the internal volume of the starting end side section including the starting end 30E is larger than the internal volume of the sound pressure hole side section including the sound pressure hole 13.

[0034] When the vibrating part 30 vibrates and air flows inside the duct part D, the smaller the cross-section of the duct part D, the greater the resistance. As the value obtained by integrating the cross-sectional areas 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 interior of the duct part D increases. When the load energy increases, the operating resistance of the vibrating part 30 increases, reducing the sensitivity in the low-frequency range and the generated sound pressure in the low-frequency range. Because the hole 3 formed in the partition wall 2 shown in FIG. 2 is determined by the vehicle model, the size of the opening area of ​​the sound pressure hole 13 is limited. Therefore, in the in-vehicle speaker 1 of the embodiment, as shown in (a), (b), and (c) above, the cross-sectional area and volume of the sound pressure space Sv are set to increase from the sound pressure hole 13 toward the inside of the case 10. Therefore, the value obtained by integrating the cross-sectional areas of each cross-section of the duct part D in the X direction over the entire length of the duct increases. Therefore, the load energy when the vibrating section 30 vibrates can be reduced, and the sensitivity in the low frequency range can be increased, making it possible to increase the reproduced sound pressure in the low frequency range.

[0035] The diagram in FIG. 9 shows simulation results of the frequency characteristics (i) of the in-vehicle 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 diagram represents the playback frequency (Hz), and the vertical axis represents the playback sound pressure (dB). In Comparative Example 1, a playback unit having the vibration section 30, magnetic circuit section 40, and damper members 36 and 37 shown in FIG. 3 was simply fixed to a baffle and operated without being housed in the case 10. In Comparative Example 2, a speaker was operated in the case 10 shown in FIGS. 1 and 2, with the cross-sectional area of ​​the internal space of the duct section D kept constant throughout its entire length from the opening area of ​​the sound pressure hole 13.

[0036] 9, the frequency characteristic (i) of the in-vehicle speaker 1 having a duct portion and the frequency characteristic (iii) of the in-vehicle speaker 1 having a duct portion are able to expand the frequency band of the reproduction frequency to, for example, a region below 100 Hz, which is the usable frequency band F for use as a subwoofer, compared to the frequency characteristic (ii) of the in-vehicle speaker 1 having a baffle attached to the baffle. Furthermore, the frequency characteristic (i) of the in-vehicle speaker 1 of the embodiment has higher sensitivity in the low-frequency range, which is the usable frequency band F, compared to the frequency characteristic (iii) of the in-vehicle speaker 1 having a duct portion with a uniform cross-sectional area.

[0037] <Modification> As shown in (A) of FIG. 7, the in-vehicle speaker 101 of the first modified example has a duct portion D whose planar shape has a constant width from the starting end 30E to partway, and then the width decreases toward the sound pressure hole 13. As shown in (B) of FIG. 7, the duct portion D has a uniform height in the side view. The internal volume of the starting end section N1 of the duct portion D is larger than the internal volume of the sound pressure hole-side section N2. As shown in (A) of FIG. 8, the in-vehicle speaker 201 of the second modified example has a duct portion D whose planar shape has a constant width along the entire length from the starting end 30E to the sound pressure hole 13. As shown in (B) of FIG. 8, the height of the duct portion D increases from the starting end 30E to partway, and then gradually decreases, decreasing toward the sound pressure hole 13. In the second modified example, the internal volume of the starting end section N1 of the duct portion D is also larger than the internal volume of the sound pressure hole-side section N2.

[0038] In the duct portion D of the in-vehicle speaker 101 of the first modified example and the in-vehicle speaker 201 of the second modified example, the internal volume of the starting end section N1 is larger than the internal volume of the sound pressure hole side section N2. In both cases, the cross-sectional area of ​​the internal space of the duct portion D in a cross section passing through the starting end 30E is larger than the cross-sectional area of ​​the internal space in a cross section passing through the center of the opening of the sound pressure hole 13. This makes it easy to achieve a good balance between the effect of expanding the usable reproduction frequency band into the low-frequency range and the effect of increasing sensitivity in the low-frequency range. [Explanation of symbols]

[0039] 1,101,201 Car speakers 2 Bulkhead 10 cases 12 Opening 13 Sound pressure hole 30 Vibration unit 30E Start 31 Vibration plate 32 Edge member 34 Voice coil (magnetic drive unit) 36,37 Damper member 40 Magnetic circuit section (magnetic drive section) As,Ao,Ah cross-sectional area D duct section Ds, Do, Dh cross section N1,Na starting compartment N2, Nc sound pressure hole side section Nb intermediate compartment Oh horizontal center line Ov vibration center line Ox Duct centerline P Sound pressure acting part S1 interior space S2 Vehicle exterior space Sv sound pressure space

Claims

1. A car speaker in which a vibration part and a magnetic drive part that drives the vibration part are housed inside a case having a sound pressure hole formed therein, and a sound pressure space that is partitioned by the vibration part and communicates with the sound pressure hole is formed inside the case, the sound pressure space is a duct portion extending from an end of the vibration portion closest to the sound pressure hole to the sound pressure hole, An in-vehicle speaker, wherein 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. 2. The in-vehicle speaker according to claim 1, wherein 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. 3. The in-vehicle speaker according to claim 2, wherein when the duct portion is divided into two sections by dividing the distance from the starting end to the sound pressure hole in half, 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. 3. The in-vehicle speaker according to claim 2, wherein 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 both the internal volume of the sound pressure hole side section including the sound pressure hole and the internal volume of the intermediate section.

5. 5. The vehicle speaker according to claim 1, wherein the cross-sectional area of ​​the inner space of the duct portion gradually decreases from the starting end toward the sound pressure hole.

6. A car speaker in which a vibration part and a magnetic drive part that drives the vibration part are housed inside a case having a sound pressure hole formed therein, and a sound pressure space that is partitioned by the vibration part and communicates with the sound pressure hole is formed inside the case, When an imaginary line passing through the center of the vibrating part and extending in the vibration direction of the vibrating part is defined as a vibration center line, and a line perpendicular to the vibration center line and extending to the center of the opening of the sound pressure hole is defined as a planar center line, An in-vehicle speaker characterized in that the width dimension of the case in a direction perpendicular to both the vibration center line and the planar center line gradually decreases from the position of the vibration center line toward the sound pressure hole.

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

Images