Bass reflex port and bass reflex type speaker

Abstract

To provide a bass reflex type speaker capable of reducing abnormal sound generated from a bass reflex port even in a situation in which input amplitude is excessive.SOLUTION: A bass reflex type speaker is provided with: a bass reflex port 20 for inputting and outputting air between a space in a housing 10 of a speaker and a space outside the housing 10; and a guide part 30 being contiguous with an inner wall of the bass reflex port 20 and having an inner wall spreading from an entrance in the housing 10 of the bass reflex port 20 to the outside in a peripheral direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a bass reflex port and a bass reflex type speaker.

Background Art

[0002] One of the main applications of a bass reflex type speaker is a subwoofer. These days, there is a demand for a subwoofer that can output a large amount of power. However, when increasing the output power of the subwoofer, the flow velocity of the air flowing in and out of the housing through the bass reflex port increases, making it easier for abnormal noises to occur. For this reason, countermeasures against abnormal noises are required. Conventionally, as a countermeasure against abnormal noises, there has been a measure of making the end of the bass reflex port have a flare shape. This measure is disclosed in, for example, Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technology disclosed in Patent Document 1 has a certain effect as a countermeasure against abnormal noises. However, when increasing the input signal level supplied to the speaker unit, there is a problem that abnormal noises occur from the bass reflex port even when the vicinity of both ends of the bass reflex port has a flare shape.

[0005] This invention has been made in view of the above circumstances, and an object thereof is to provide a technical means capable of reducing abnormal noises generated from the bass reflex port even in a situation where the input signal level is excessive.

Means for Solving the Problems

[0006] The present invention provides a bass reflex port characterized by comprising a tubular body portion and a guide portion having an inner wall that is continuous with the inner wall of the tubular body portion and extends outward in the circumferential direction from the entrance and exit of the tubular body portion disposed within the housing of a speaker.

[0007] According to the present invention, since the air flowing in and out between the space inside the housing of the speaker and the space outside the housing is guided by the inner wall of the tubular body portion and the inner wall of the guide portion and flows, it is possible to hardly cause separation of the air flow near the entrance and exit inside the housing of the tubular body portion. Therefore, it is possible to reduce the turbulence of the air flow in the bass reflex port and reduce abnormal noise.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0010] <First Embodiment> FIG. 1 is a perspective view of a bass-reflex speaker 101 according to the first embodiment of the present invention, seen from obliquely above. FIG. 2 is a cross-sectional view showing a first configuration obtained by cutting the bass-reflex speaker 101 with a plane that includes the central axis ax of the bass-reflex port 20 and is parallel to the installation surface of the speaker unit SP in the housing 10. FIG. 3 is a cross-sectional view showing a second configuration obtained by cutting the bass-reflex speaker 101 with a plane that includes the central axis ax of the bass-reflex port 20 and is parallel to the installation surface of the speaker unit SP in the housing 10. FIG. 4 is a cross-sectional view schematically showing the cross-sectional configuration of the bass-reflex speaker 101 from the front. The first configuration shown in FIG. 2 is obtained by applying a first measure for preventing abnormal noise generation to the bass-reflex speaker. The second configuration shown in FIG. 3 is the configuration of the bass-reflex speaker according to the present embodiment, in which, in addition to the first measure, a second measure for preventing abnormal noise generation is applied to the bass-reflex speaker. FIGS. 1 and 4 correspond to the second configuration. As shown in FIGS. 1 to 4, the bass-reflex speaker 101 includes a housing 10, a speaker unit SP, a bass-reflex port 20 that is a tubular portion, and a guide portion 30.

[0011] The housing 10 is a rectangular parallelepiped surrounded by six surfaces, and the speaker unit SP is provided on the front surface that functions as a baffle surface among the six surfaces surrounding the housing 10.

[0012] The bass-reflex port 20 is a hollow, substantially cylindrical tube body, which can be divided into a straight portion 22 with a constant cross-sectional area (the area of a cross-section perpendicular to the tube axis of the space surrounded by the inner wall of the bass-reflex port 20) in the tube axis direction, and flare portions 24 and 25 that function as air inlets and outlets at both ends thereof. The flare portion 24 has a shape in which the cross-sectional area gradually expands from near the boundary between the straight portion 22 and the flare portion 24 toward the opening end 28. The opening end 28 of the flare portion 24 is located on the upper surface of the housing 10 and serves as an opening in the upper surface of the housing 10. The flare portion 25 has a flare shape in which the cross-sectional area gradually expands from near the boundary between the straight portion 22 and the flare portion 25 toward the opening end 29. The opening end 29 of the flare portion 25 is inside the housing 10. This opening end 29 is the inlet and outlet inside the housing 10 of the bass-reflex port 20.

[0013] In the present embodiment, as a first measure for preventing abnormal noise generation, the first configuration shown in FIG. 2 is adopted. That is, in the present embodiment, the opening end 29, which is the inlet and outlet inside the housing 10 of the bass-reflex port 20, is connected to the guide portion 30 as shown in FIG. 2, and the opening end 29 serves as an opening of the guide portion 30. This guide portion 30 is continuous with the inner wall of the bass-reflex port 20 and has an inner wall that extends outward in the circumferential direction from the opening end 29, which is the inlet and outlet inside the housing 10 of the bass-reflex port 20. The inner wall surface of this guide portion 30 is orthogonal to the central axis ax of the bass-reflex port 20. Note that the orthogonality includes the case where the angle between the inner wall surface of the guide portion 30 and the central axis ax of the bass-reflex port 20 is approximately 90°, and includes, for example, the range of variations in the manufacture of the guide portion 30.

[0014] Furthermore, in the present embodiment, in addition to the above first measure, in order to take a second measure for preventing abnormal noise generation, a second configuration is adopted. That is, in the present embodiment, as shown in FIGS. 3 and 4, a wall 40 that faces the inner wall of the guide portion 30 at a predetermined distance h is supported inside the housing 10. The inner wall of the wall 40 and the guide portion 30 are parallel to each other. Also, in the illustrated example, the wall 40 and the guide portion 30 are parallel to the lower surface of the housing 10, but they do not have to be parallel. The wall 40 is fixed to the housing 10 by, for example, a connecting rod (not shown) or the like.

[0015] In the configuration shown in FIGS. 1 to 4, the air flow guided by the inner wall of the bass reflex port 20 flows out of the flow path in the bass reflex port 20 and then is guided by the inner wall of the guide portion 30. Therefore, the separation of the air flow is less likely to occur. This is the effect of the first countermeasure. Also, the air flow guided by the inner wall of the bass reflex port 20, after flowing out of the flow path in the bass reflex port 20, radially advances through the space between the inner wall of the guide portion 30 and the wall 40. Therefore, a sudden change in the cross-sectional area of the air flow is alleviated, and the separation of the air flow is less likely to occur. This is the effect of the second countermeasure.

[0016] In the present embodiment, the distance h between the guide portion 30 and the wall 40 is determined so as not to cause a discontinuous change in the cross-sectional area in the air flow path. Specifically, it is as follows. The cross-sectional area S2 of the air flow that radially advances through the space between the inner wall of the guide portion 30 and the wall 40, when the distance between the guide portion 30 and the wall 40 is h and the distance from the tube axis ax of the bass reflex port 20 to the cross-section of the air flow is r, is S2 = 2πrh, and it increases in proportion to the distance r from the tube axis ax of the cross-section of the air flow. Therefore, when the opening end 29 forms a circle with a radius r0, the distance h between the guide portion 30 and the wall 40 is set to r0 / 2. By doing so, the cross-sectional area S of the flow path in the flare portion 25 at the opening end 29 becomes πr0 2 whereas the cross-sectional area S2 of the flow path between the guide portion 30 and the wall 40 at the opening end 29 is 2πr0h = 2πr0(r0 / 2) = πr0 2As a result, the cross-sectional areas of both become equal. Therefore, when the air flow proceeds from the bass reflex port 20 to the flow path between the guide portion 30 and the wall 40, no discontinuous change in the cross-sectional area of the flow path occurs. Note that, depending on various conditions such as the shape of the flare portion 25, the cross-sectional area S2 of the flow path between the guide portion 30 and the wall 40 at the opening end 29 may be made to match not the cross-sectional area S of the flow path within the flare portion 25 but the cross-sectional area S1 of the flow path within the straight portion 22. Alternatively, the cross-sectional area S2 of the flow path between the guide portion 30 and the wall 40 at the opening end 29 may be made to match the cross-sectional area S at a position in front of the opening end 29 of the flow path within the flare portion 25. Ideally, the cross-sectional area S2 of the flow path between the guide portion 30 and the wall 40 at the opening end 29 is preferably determined as described above. However, if the discontinuity of the cross-sectional area of the flow path is small, the effect of preventing abnormal noise generation can be obtained. Specifically, if the cross-sectional area S2 of the flow path between the guide portion 30 and the wall 40 at the opening end 29 is set to a cross-sectional area within the range from about twice the cross-sectional area S1 of the flow path within the straight portion 22 to about 2.5 times the cross-sectional area S at the opening end 29 of the flow path within the flare portion 25, it is effective in preventing abnormal noise generation.

[0017] The planar shapes of the guide portion 30 and the wall 40 are arbitrary. FIGS. 5(a) and (b) are diagrams showing a first example of the planar shapes of the guide portion 30 and the wall 40, and FIGS. 6(a) and (b) are diagrams showing a second example of the planar shapes of the guide portion 30 and the wall 40. Here, FIGS. 5(a) and 6(a) show the bass reflex port 20, the guide portion 30, and the wall 40 as viewed from the side, and FIGS. 5(b) and 6(b) show the bass reflex port 20, the guide portion 30, and the wall 40 as viewed from the bottom side of the housing 10.

[0018] In the first example shown in FIGS. 5(a) and (b), the planar shapes of the guide part 30 and the wall 40 are squares of the same size. In the second example shown in FIGS. 6(a) and (b), the planar shapes of the guide part 30 and the wall 40 are circles of the same size. In any configuration, an effect is obtained in which no discontinuous change in the cross-sectional area of the flow path occurs when the air flow proceeds from the bass reflex port 20 to the flow path between the guide part 30 and the wall 40. However, the air flow that has entered from the side of the bass reflex port 20 radially proceeds through the region between the guide part 30 and the wall 40 while expanding the cross-sectional area and exits into the space within the housing 10. In order to mitigate the change in the cross-sectional area of the air flow when exiting from the region between the guide part 30 and the wall 40 into the space within the housing 10, it is necessary to make the cross-sectional area of the air flow sufficiently large within the region between the guide part 30 and the wall 40. Therefore, in the first and second examples, the shortest distance R among the distances from the tube axis ax of the bass reflex port 20 to the ends of the guide part 30 and the wall 40 needs to be a length that can make the cross-sectional area of the air flow sufficiently large.

[0019] In the above configuration, when the diaphragm of the speaker unit SP vibrates, pressure vibrations are generated in the housing 10 due to this vibration. When the pressure inside the housing 10 increases, an air flow is generated that flows from inside the housing 10 to the outside of the housing 10 through the air flow path between the guide part 30 and the wall 40 and the bass reflex port 20. Also, when the pressure inside the housing 10 decreases, an air flow is generated that flows from outside the housing 10 into the housing 10 through the bass reflex port 20 and the air flow path between the wall 40 and the guide part 30. At this time, the bass reflex port 20 and the housing 10 function as a Helmholtz resonator having a resonance frequency near the lower limit frequency of the band where the sound pressure is flat in the output characteristics of the bass reflex type speaker 101.

[0020] In this bass-reflex type speaker 101, in the section from inside the bass-reflex port 20 to the air flow path between the guide portion 30 and the wall 40, the air flow is guided by the inner wall of the guide portion 30, and there is no abrupt change in the cross-sectional area of the air flow path. Therefore, while the bass-reflex port 20 and the housing 10 function as a Helmholtz resonator, since the air flow is guided by the inner wall of the bass-reflex port 20 and the inner wall of the guide portion 30, the separation of the air flow hardly occurs. Also, in the air flow path composed of the air flow path in the bass-reflex port 20 and the air flow path between the guide portion 30 and the wall 40, no large negative pressure gradient occurs, and abnormal noise due to the separation of the air flow can be reduced. Further, in this bass-reflex type speaker 101, the air flow that has advanced from the bass-reflex port 20 between the guide portion 30 and the wall 40 is made to travel radially, and the cross-sectional area of the air flow is gradually increased and discharged into the space inside the housing 10. And the discharge of the air flow from inside the housing 10 to the outside of the housing 10 goes through the reverse process. Therefore, separation of the air flow can be prevented throughout the entire section of the air flow path, and abnormal noise can be reduced.

[0021] Also, in the present embodiment, the inner wall surface of the straight portion 22 of the bass-reflex port 20 and the inner wall surface of the guide portion 30 facing the wall 40 are connected by the inner wall surface of the flare portion 25 forming a curved surface. Here, there is no step between the inner wall surface of the straight portion 22 and the inner wall surface of the flare portion 25, and there is also no step between the inner wall surface of the flare portion 25 and the inner wall surface of the guide portion 30. Thus, the region from the inner wall surface of the straight portion 22 of the bass-reflex port 22 to the inner wall surface of the guide portion 30 is a continuous and smooth curved surface. Therefore, in the present embodiment, the cross-sectional area of the air flow path surrounded by the inner wall of the bass-reflex port 20 continuously increases as it proceeds from the position in front of the entrance and exit inside the bass-reflex port, which is the boundary between the straight portion 22 and the flare portion 25, into the guide portion 30. Therefore, in the process of the air flow reaching the flow path between the guide portion 30 and the wall 40 from the bass-reflex port 20, separation of the air flow from the inner wall of the bass-reflex port 20 can be prevented, and abnormal noise can be reduced.

[0022] FIG. 7 is a diagram showing the effects of the present embodiment. In FIG. 7, on a two-dimensional coordinate system with the horizontal axis representing frequency and the vertical axis representing volume, the frequency characteristic SP0 of the SPL (Sound Pressure Level) of the input audio signal, the frequency characteristic SP1 of the SPL output by the bass-reflex type speaker of the comparative example for this input audio signal, and the frequency characteristic SP2 of the SPL output by the bass-reflex type speaker 101 of the present embodiment for this input audio signal are shown.

[0023] The bass-reflex type speaker of the comparative example is a bass-reflex type speaker provided with a bass-reflex port having flare portions with an elliptical cross-section at both ends. The input audio signal is an audio signal of movie content. In this example, a portion of 0.25 seconds that reproduces bass, which is particularly prone to abnormal sounds, is cut out from the audio signal of the movie content and used as the input audio signal for the speaker.

[0024] As can be seen from the frequency characteristic SP0 of the input audio signal shown in FIG. 7, the input audio signal hardly includes a band of several hundred hertz or more. However, when this input audio signal is applied to the bass-reflex port type speaker of the comparative example, the SPL of the output sound obtained from the same bass-reflex port type speaker exceeds the SPL of the input audio signal in the high frequency range. The increase in the SPL of the output sound with respect to the SPL of this input audio signal is the high frequency noise (abnormal sound) generated by the bass-reflex type speaker of the comparative example.

[0025] On the other hand, according to the bass-reflex type speaker of the present embodiment, the increase in the sound pressure level SP2 of the output sound in the high frequency range with respect to the sound pressure level SP0 of the input audio signal is smaller than that in the case of the comparative example. That is, in the present embodiment, the sound pressure level of the abnormal sound is smaller than that in the comparative example. Thus, according to the present embodiment, the abnormal sound can be effectively reduced more than in the comparative example.

[0026] <Modification Example of the First Embodiment> FIG. 8 is a cross-sectional view schematically showing the configuration of a bass-reflex speaker 101a which is a first modification of the first embodiment. In FIG. 8 and FIGS. 9 and 10 to be described later, the illustration of the speaker unit SP is omitted, and cross-sections of the housing 10, the bass-reflex port 20, etc. are shown by lines. In FIGS. 8 to 10, the same reference numerals are used for the portions corresponding to the respective portions shown in FIGS. 1 to 4 above, and the description thereof is omitted.

[0027] In this first modification, the facing surface of the guide portion 30 with the wall 40 in the housing 10 forms an angle greater than 180° and less than 270° with the inner wall of the straight portion 22 of the bass-reflex port 20. Further, the wall 40 in the housing 10 facing the guide portion 30 bulges in a mountain shape such that the region facing the entrance and exit of the bass-reflex port 20 is at the top.

[0028] Thus, the wall 40 does not need to be planar as in the first embodiment, and may be a curved surface. Even in this aspect, the same effects as those of the first embodiment can be obtained. Further, according to this aspect, the radius of curvature of each part of the inner wall from the inner wall of the straight portion 22 to the inner wall of the guide portion 30 via the inner wall of the flare portion 25 can be made larger than that of the first embodiment, so that the separation of the air flow from the inner wall can be effectively prevented.

[0029] FIG. 9 is a cross-sectional view schematically showing the configuration of a bass-reflex speaker 101b which is a second modification of the first embodiment. In this aspect, there is no wall 40, and the wall forming the bottom surface of the housing 10 faces the guide portion 30 and serves as the wall 40 of the first embodiment. Even in this aspect, the same effects as those of the first embodiment can be obtained. Further, according to this aspect, since it is not necessary to provide the wall 40 of the first embodiment, the bass-reflex speaker 101b can be made inexpensive. Further, according to this aspect, the bottom surface of the housing 10 can be brought closer to the flare portion 25 of the bass-reflex port 20, so that the housing 10 can be made smaller than in the first embodiment.

[0030] FIG. 10 is a cross-sectional view schematically showing the configuration of a bass-reflex speaker 101c according to a third modification of the first embodiment. This third modification is a combination of the first modification and the second modification. Similar to the second modification, in this third modification, there is no wall 40, and the wall forming the bottom surface of the housing 10 serves as the wall 40. And in the third modification, the facing surface of the guide portion 30 with respect to the wall 40 in the housing 10 forms an angle greater than 180° and less than 270° with respect to the inner wall of the straight portion 22 of the bass-reflex port 20. Also, the wall forming the bottom surface of the housing 10 facing the guide portion 30 is raised in a mountain shape such that the region facing the entrance and exit of the bass-reflex port 20 is at the top.

[0031] Even in this aspect, the same effects as those of the first embodiment can be obtained. Also, according to this aspect, since the radius of curvature of each part of the inner wall from the inner wall of the straight portion 22 through the inner wall of the flare portion 25 to the inner wall of the guide portion 30 can be made larger than that of the first embodiment, the separation of the air flow from the inner wall can be effectively prevented. Also, according to this aspect, since there is no need to provide the wall 40 of the first embodiment, the bass-reflex speaker 101c can be made inexpensive. Also, according to this aspect, since the bottom surface of the housing 10 can be brought closer to the flare portion 25 of the bass-reflex port 20, the housing 10 can be made smaller than the first embodiment.

[0032] <Second Embodiment> FIG. 11 is a perspective view of a bass-reflex speaker 102 according to the second embodiment of the present invention as viewed obliquely from above. FIG. 12 is a cross-sectional view showing the configuration of the same bass-reflex speaker 102 cut by a plane including the central axis ax of the bass-reflex port 20 and parallel to the installation surface of the speaker unit SP in the housing 10. FIG. 13 is a cross-sectional view schematically showing the cross-sectional configuration of the same bass-reflex speaker 102 from the front. In FIGS. 11 to 13, the same reference numerals are used for the parts corresponding to those in FIGS. 1, 3, and 4 described above, and the description thereof is omitted.

[0033] The bass-reflex speaker 102 according to this embodiment has a configuration in which a wall 50 is added to the bass-reflex speaker 101 of the first embodiment. This wall 50 faces the wall forming the upper surface of the housing 10 with a distance g therebetween. In this embodiment, the space inside the bass-reflex port 20 is connected to the space inside the housing 10 through the air flow path between the guide portion 30 and the wall 40, similar to the first embodiment. On the other hand, it is connected to the space outside the housing 10 (more precisely, the space outside the housing 10 and not sandwiched between the wall 50 and the housing 10) through the air flow path between the housing 10 and the wall 50.

[0034] In this embodiment, when the radius of the opening end (opening circular region) 28 of the flare portion 24 is the same as the radius of the opening end (opening circular region) 29 of the flare portion 25, the distance g may be the same as the distance h between the guide portion 30 and the wall 40. Further, when the radius of the opening end (opening circular region) 28 of the flare portion 24 is different from the radius of the opening end (opening circular region) 29 of the flare portion 25, the distance g may be calculated in the same manner as the method for determining the distance h in the first embodiment. That is, when the radius of the opening circular region of the flare portion 24 is r0, the distance g may be, for example, r0 / 2.

[0035] By doing so, the cross-sectional area of the flow path between the housing 10 and the wall 50 at the opening end 28 becomes equal to (or close to) the cross-sectional area of the opening end 28 of the flare portion 24, and a discontinuous change in the cross-sectional area of the air flow path can be eliminated in the section of the air flow path composed of the section inside the bass-reflex port 20 and the section between the housing 10 and the wall 50.

[0036] According to this embodiment, both the turbulence of the air flow at the entrance and exit inside the housing 10 of the bass-reflex port 20 and the turbulence of the air flow at the entrance and exit outside the housing 10 of the bass-reflex port 20 can be prevented. Therefore, abnormal noise can be reduced more effectively than in the first embodiment.

[0037] FIG. 14 is a diagram showing the effects of this embodiment. In FIG. 14, the frequency characteristic SP0 of the SPL of the input audio signal similar to that of the first embodiment (see FIG. 7), the frequency characteristic SP1 of the SPL output by the bass-reflex type speaker of the comparative example with respect to this input audio signal, and the frequency characteristic SP3 of the SPL output by the bass-reflex type speaker 102 of this embodiment with respect to this input audio signal are shown. As is clear from comparing FIGS. 14 and 7, the high-frequency sound pressure level SP3 obtained from the bass-reflex type speaker of this embodiment is lower than the high-frequency sound pressure level SP2 obtained from the bass-reflex type speaker of the first embodiment. That is, according to this embodiment, abnormal noise can be reduced more effectively than in the first embodiment.

[0038] <Modification Example of the Second Embodiment> FIG. 15 is a cross-sectional view schematically showing the configuration of a bass-reflex type speaker 102a which is a first modification example of the second embodiment. In this FIG. 15 and FIGS. 16 to 18 described later, the illustration of the speaker unit SP is omitted, and the cross-sections of the housing 10, the bass-reflex port 20, etc. are shown by lines. In addition, in these FIGS. 15 to 18, the same reference numerals are used for the parts corresponding to the parts shown in FIGS. 1, 3, 4, and 11 to 13 mentioned above, and the description thereof is omitted.

[0039] In this first modification example, similar to the first modification example of the first embodiment, the facing surface of the guide portion 30 with the wall 40 inside the housing 10 forms an angle larger than 180° and smaller than 270° with respect to the inner wall of the straight portion 22 of the bass-reflex port 20. Further, the wall 40 inside the housing 10 facing the guide portion 30 bulges in a mountain shape so that the region facing the entrance and exit of the bass-reflex port 20 is at the top. Other points are the same as those of the second embodiment.

[0040] Even in this aspect, the same effects as those of the second embodiment can be obtained. Further, according to this aspect, since the radius of curvature of each part of the inner wall from the inner wall of the straight portion 22 to the inner wall of the guide portion 30 via the inner wall of the flare portion 25 can be made larger than that of the second embodiment, peeling of the air flow from the inner wall can be effectively prevented.

[0041] FIG. 16 is a cross-sectional view schematically showing the configuration of a bass-reflex speaker 102b which is a second modification of the second embodiment. In this second modification, the surface of the wall forming the upper surface of the housing 10 that faces the wall 50 forms an angle greater than 180° and less than 270° with respect to the inner wall of the straight portion 22 of the bass-reflex port 20. Further, the wall 50 bulges in a mountain shape such that the region facing the entrance and exit of the bass-reflex port 20 is at the top. Other points are the same as those in the second embodiment described above.

[0042] Also in this aspect, the same effects as those in the second embodiment described above can be obtained. Further, according to this aspect, since the radius of curvature at each location from the inner wall of the straight portion 22 to the outer wall of the upper surface of the housing 10 via the inner wall of the flare portion 24 can be made larger than that in the second embodiment, peeling from the inner wall of the air flow path can be effectively prevented.

[0043] FIG. 17 is a cross-sectional view schematically showing the configuration of a bass-reflex speaker 102c which is a third modification of the second embodiment. This third modification combines the first modification and the second modification described above.

[0044] Also in this aspect, the same effects as those in the second embodiment described above can be obtained. Further, according to this aspect, similar to the first modification, the radius of curvature at each location of the inner wall from the inner wall of the straight portion 22 to the inner wall of the guide portion 30 via the inner wall of the flare portion 25 can be made larger than that in the second embodiment. Further, according to this aspect, similar to the second modification, the radius of curvature at each location from the inner wall of the straight portion 22 to the outer wall of the upper surface of the housing 10 via the inner wall of the flare portion 24 can be made larger than that in the second embodiment. Therefore, peeling from the inner wall of the air flow path can be effectively prevented.

[0045] FIG. 18 is a cross-sectional view schematically showing the configuration of a bass-reflex type speaker 102d which is a fourth modification of the second embodiment. This fourth modification is obtained by making the same modification as the second modification of the first embodiment to the above-described second embodiment. That is, in this fourth modification, the wall 40 in the housing 10 is not provided, and the wall forming the bottom surface of the housing 10 serves as the wall 40.

[0046] According to this aspect, since it is not necessary to provide the wall 40, the bass-reflex type speaker 102d can be made inexpensive. Further, according to this aspect, since the bottom surface of the housing 10 can be brought closer to the flare portion 25 of the bass-reflex port 20, the housing 10 can be made smaller than in the second embodiment.

[0047] Although illustration is omitted, it is also possible to make the modifications of the first to third modifications of the second embodiment to this fourth modification.

[0048] <Other Embodiments> As described above, each embodiment of the present invention has been described, but other embodiments are also conceivable for the present invention. For example, as follows.

[0049] (1) In each of the above embodiments, the bass-reflex port is attached to the upper surface of the housing, but the attachment position of the bass-reflex port may be any of the upper, lower, left, right, front, and rear surfaces of the housing.

[0050] (2) The housing, the bass-reflex port, and the guide may be integrally formed, or each part may be manufactured separately and connected to each other. Further, the bass-reflex port and the guide may be integrally formed. Further, in each of the above embodiments, the tubular portion is used as the bass-reflex port, and a guide is added to this bass-reflex port. However, a bass-reflex port with a guide added to the tubular portion that is the bass-reflex port may be treated as the bass-reflex port.

[0051] (3) In the above-described first embodiment, the distance h between the guide portion 30 and the wall 40 may be uniform, or the distance h may be increased as the distance from the tube axis ax of the bus ref port 20 increases. According to this aspect, as the distance from the tube axis ax of the bus ref port 20 increases, the gradient of the increase in the cross-sectional area of the air flow path between the guide portion 30 and the wall 40 can be increased. Therefore, even in a situation where the areas of the guide portion 30 and the wall 40 cannot be increased, the cross-sectional area of the air flow flowing between the guide portion 30 and the wall 40 can be increased and discharged into the housing 10, and abnormal noise can be reduced.

[0052] (4) In each of the above embodiments, the portions other than the entrances and exits of the bus ref port 20 are arranged away from the wall of the housing, but a part of the side surface from one entrance and exit of the bus ref port 20 to the other entrance and exit may be fixed to the wall of the housing. Alternatively, the wall of the housing may also serve as a part of the side surface of the housing bus ref port. In these aspects, a guide portion 30 having a shape that protrudes outward in the circumferential direction from a section excluding the section fixed to the wall of the housing among the entire circumference of the entrances and exits of the bus ref port 20 may be provided.

[0053] (5) The length of the guide portion 30 (or the wall 40) that spreads toward the inner wall of the housing may be within the range until it reaches the inner wall of the housing. Also, a part of the periphery of the guide portion 30 (or the wall 40) that spreads radially from the entrances and exits of the bus ref port 20 may reach the inner wall of the housing. However, at least a part of the periphery of the guide portion 30 (or the wall 40) is configured not to reach the inner wall of the housing and to be non-contact with the inner wall of the housing. That is, the space inside the housing does not have to be divided by the guide portion 30 or the wall 40.

[0054] (6) The width or planar shape of the wall 40 does not have to be the same as that of the guide portion 30. The wall 40 only needs to have a width and planar shape that can cover the opening end 29.

[0055] (7) A part of the bus ref port 20 may be located outside the housing 10.

[0056] (8) In addition to being implemented as the bass-reflex type speaker disclosed in each of the above embodiments, the present invention can also be implemented as a bass-reflex port in which the bass-reflex port 20 (i.e., the tubular portion) and the guide portion 30 in each of the above embodiments are integrated, or as a bass-reflex port in which the bass-reflex port 20 (i.e., the tubular portion), the guide portion 30, and the wall 40 are integrated.

[0057] (9) In the first embodiment, in addition to the first countermeasure, the second countermeasure was taken. However, if the desired abnormal noise prevention effect can be obtained only by the first countermeasure, only the first countermeasure may be taken. The same applies to other embodiments. That is, a configuration in which the wall 40 is not installed can be applied to the configurations of FIGS. 8, 11, 12, 13, 15, 16, and 17, such as the first configuration of the first embodiment described with reference to FIG. 2, and it can also be implemented as a configuration in which the wall 40 is not installed.

Description of Reference Numerals

[0058] 101, 101a, 101b, 101c, 102, 102a, 102b, 102c, 102d... bass-reflex type speakers, 10... housing, SP... speaker unit, 20... bass-reflex port, 22... straight portion, 24, 25... flare portions, 28, 29... open ends, 30... guide portion, 40, 50... walls.

Claims

1. a tubular body portion; a first guide portion having an inner wall that is continuous with the inner wall of the tubular body portion and extends from a first inlet / outlet of the tubular body portion to an outer end in the circumferential direction; a first wall that forms an air flow path passing through the inside of the tubular body portion between the first guide portion and the inner wall thereof; characterized by comprising: the tubular body portion consists of a straight portion having a constant cross-sectional area in the tube axis direction and a flare portion that functions as an air inlet / outlet at an end of the straight portion, and the flare portion has a shape in which the cross-sectional area gradually expands from near the boundary with the straight portion toward the open end; the first guide portion is connected to the open end of the flare portion, faces the first wall, and includes an inner wall that extends from the first inlet / outlet to an outer end in the circumferential direction, and by forming an air flow path passing through the inside of the tubular body portion between the inner wall that extends to this end and the first wall, the air passing through the inside of the tubular body portion is guided from the first inlet / outlet to the outside in the circumferential direction; the cross-sectional area of the flow path between the first guide portion and the first wall at the open end of the flare portion is within a range from about twice the cross-sectional area of the flow path in the straight portion to about 2.5 times the cross-sectional area at the open end of the flow path in the flare portion; a bass reflex port, characterized in that the cross-sectional area of the air flow path passing through the tubular body portion continuously increases from before the first inlet / outlet inside the tubular body portion to the outer end in the circumferential direction of the first guide portion.

2. The bass reflex port according to claim 1, characterized in that the inner wall of the first guide portion forms an angle greater than 180° and less than 270° with respect to the inner wall of the tubular body portion, and the first wall bulges in a mountain shape such that the region facing the first inlet / outlet is at the crest.

3. a speaker housing; a bass reflex port disposed inside the housing; a first guide portion having an inner wall that is continuous with the inner wall of the bass reflex port and extends from a first inlet / outlet of the bass reflex port inside the housing to an outer end in the circumferential direction, and forms an air flow path passing through the inside of the bass reflex port between the first wall constituting the housing; characterized by comprising: the bass reflex port consists of a straight portion having a constant cross-sectional area in the tube axis direction and a flare portion that functions as an air inlet / outlet at an end of the straight portion, and the flare portion has a shape in which the cross-sectional area gradually expands from near the boundary with the straight portion toward the open end; The first guide part is connected to the open end of the flare part, faces the first wall, and includes an inner wall that extends from the first entrance and exit to the outer end in the circumferential direction. By forming an air flow path that passes through the inside of the tubular part between the inner wall that extends to this end and the first wall, the air passing through the inside of the tubular part is guided from the first entrance and exit to the outside in the circumferential direction. The cross-sectional area of the flow path between the first guide part and the first wall at the open end of the flare part is within a range from about twice the cross-sectional area of the flow path in the straight part to about 2.5 times the cross-sectional area at the open end of the flow path in the flare part. A bass-reflex type speaker, characterized in that the cross-sectional area of the air flow path through the bass-reflex port continuously increases as it proceeds from in front of the first entrance and exit in the bass-reflex port to the outer end in the circumferential direction of the first guide part.

4. The inner wall of the first guide part forms an angle greater than 180° and less than 270° with respect to the inner wall of the bass-reflex port, and the first wall is raised in a mountain shape such that the region facing the first entrance and exit is at the peak. The bass-reflex type speaker according to claim 3.

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