Bus-ref port and bus-ref 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] A main use of a bass reflex type speaker is a subwoofer. These days, there is a demand for a subwoofer capable of high output. However, when increasing the output of the subwoofer, the flow velocity of the air flow entering and leaving the inside and outside 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 into 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 is made into 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 the 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 the 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, viewed obliquely from above. FIG. 2 is a cross-sectional view showing a first configuration obtained by cutting the bass-reflex speaker 101 with 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. 3 is a cross-sectional view showing a second configuration obtained by cutting the bass-reflex speaker 101 with 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. 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, and 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 open end 28. The open 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 open end 29. The open end 29 of the flare portion 25 is inside the housing 10. This open 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 open 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 open 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 open 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 orthogonal 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 manufacturing 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. Further, the air flow guided by the inner wall of the bass reflex port 20 radially proceeds through the space between the inner wall of the guide portion 30 and the wall 40 after flowing out of the flow path in the bass reflex port 20. Therefore, a rapid 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 radially proceeding through the space between the inner wall of the guide portion 30 and the wall 40 is S2 = 2πrh 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, 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. 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 coincide with the cross-sectional area S1 of the flow path in the straight portion 22 instead of the cross-sectional area S of the flow path in the flare portion 25 at the opening end 29. 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 coincide with the cross-sectional area S at a position in front of the opening end 29 of the flow path in 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 within the range from about twice the cross-sectional area S1 of the flow path in the straight portion 22 to about 2.5 times the cross-sectional area S at the opening end 29 of the flow path in 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 entering 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 inside 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 inside 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 the outside of 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, the air flow is guided by the inner wall of the bass-reflex port 20 and the inner wall of the guide portion 30, so that 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 reverse pressure gradient occurs, and the 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 in 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, the separation of the air flow can be prevented throughout the entire section of the air flow path, and the 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 that faces the wall 40 are connected by the inner wall surface of the flare portion 25 that forms 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 advances from the position in front of the entrance / exit in the bass-reflex port, which is the boundary between the straight portion 22 and the flare portion 25, to the guide portion 30. Therefore, in the process in which the air flow reaches the flow path between the guide portion 30 and the wall 40 from the bass-reflex port 20, the separation of the air flow from the inner wall of the bass-reflex port 20 can be prevented, and the 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, from the audio signal of the movie content is cut out 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 contains a band of several hundred hertz or more. However, when this input audio signal is given 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 compared to 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 type 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 the 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 respect to 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 in 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 through the inner wall of the flare portion 25 to the inner wall of the guide portion 30 can be made larger than that in 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 type 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 in the first embodiment. Even in this aspect, the same effects as in the first embodiment can be obtained. Further, according to this aspect, since it is not necessary to provide the wall 40 in the first embodiment, the bass-reflex type 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 type speaker 101c which is 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 surface of the guide portion 30 facing 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 bulges in a mountain shape such that the region facing the entrance and exit of the bass-reflex port 20 is at the top.

[0031] Also in this aspect, the same effects as those of the first 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 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 it is not necessary to provide the wall 40 of the first embodiment, the bass-reflex type 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 in the first embodiment.

[0032] <Second Embodiment> FIG. 11 is a perspective view of a bass-reflex type speaker 102 which is the second embodiment of the present invention, viewed obliquely from above. FIG. 12 is a cross-sectional view showing the configuration of the same bass-reflex type 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 type speaker 102 from the front. In FIGS. 11 to 13, the same reference numerals are used for the parts corresponding to the parts of FIGS. 1, 3, and 4 described above, and the description thereof is omitted.

[0033] The bass-reflex type speaker 102 according to this embodiment has a configuration in which a wall 50 is added to the bass-reflex type 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. Also, 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 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, a discontinuous change in the cross-sectional area of the air flow path can be eliminated.

[0036] According to this embodiment, it is possible to prevent 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. Therefore, abnormal noise can be reduced more effectively than in the first embodiment.

[0037] FIG. 14 is a diagram showing the effects of the present 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 for this input audio signal, and the frequency characteristic SP3 of the SPL output by the bass-reflex type speaker 102 of the present embodiment for 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 the present 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 the present 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 opposing surface of the guide part 30 to the wall 40 inside the housing 10 forms an angle greater than 180° and less than 270° with respect to the inner wall of the straight part 22 of the bass-reflex port 20. Further, the wall 40 inside the housing 10 facing the guide part 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. 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, the radius of curvature of each part of the inner wall from the inner wall of the straight part 22 to the inner wall of the flare part 25 and then to the inner wall of the guide part 30 can be made larger than that of the second embodiment, so that the separation 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 type 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 in the above-described second embodiment.

[0042] Also in this aspect, the same effects as in the above-described second embodiment 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 in the above-described 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 type speaker 102c which is a third modification of the second embodiment. This third modification combines the above-described first and second modifications.

[0044] Also in this aspect, the same effects as in the above-described second embodiment can be obtained. Further, according to this aspect, similar to the above-described 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 in the above-described second embodiment. Further, according to this aspect, similar to the above-described 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 in the above-described 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 speaker 102d which is a fourth modification of the second embodiment. This fourth modification is obtained by applying 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 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 apply 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 location 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 portion may be integrally formed, or each part may be manufactured separately and connected to each other. Further, the bass-reflex port and the guide portion may be integrally formed. Also, in each of the above embodiments, the tubular portion is used as the bass-reflex port, and a guide portion is added to this bass-reflex port. However, a tubular portion with a guide portion added thereto may be treated as the bass-reflex port.

[0051] (3) In the above 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 may be provided 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.

[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 capable of covering 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 sound 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.

Explanation 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... opening ends, 30... guide portion, 40, 50... walls.

Claims

1. A tube portion; a first guide portion having an inner wall that is continuous with the inner wall of the tubular portion and that extends from a first opening of the tubular portion to an outer end in a circumferential direction; a first wall that forms a flow path for air passing through the inside of the tubular body portion between the first wall and an inner wall of the first guide portion; a second guide portion having an inner wall continuous with the inner wall of the tubular portion and extending outward in a circumferential direction from a second entrance on the opposite side of the tubular portion from the first entrance; a second wall that forms a flow path for air passing through the inside of the tubular body portion between the second wall and an inner wall of the second guide portion; Equipped with a cross-sectional area of ​​an air flow path through the tubular portion continuously increases from a position immediately before the first opening in the tubular portion toward an outer end in the circumferential direction of the first guide portion; A bass reflex port, characterized in that a cross-sectional area of ​​an air flow path through the tubular portion increases continuously from just before the second entrance in the tubular portion toward the outside in the circumferential direction of the second guide portion.

2. A bass reflex port as described in 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 tube portion, and the first wall rises like a mountain with the area facing the first entrance / exit as its apex.

3. A bass reflex port as described in claim 1, characterized in that the inner wall of the first guide portion and the inner wall of the second guide portion form an angle greater than 180° and less than 270° with respect to the inner wall of the tube portion, the first wall rises in a mountain-like shape with the area facing the first entrance / exit as its apex, and the second wall rises in a mountain-like shape with the area facing the second entrance / exit as its apex.

4. A speaker housing; a bass reflex port disposed within the housing; a first guide portion having an inner wall that is continuous with an inner wall of the bass reflex port and that extends from a first entrance / exit in the housing of the bass reflex port to an end portion on an outer side in a circumferential direction, the first guide portion forming a flow path for air passing through the inside of the bass reflex port between the first wall constituting the housing and the first guide portion; a second guide portion having an inner wall that is continuous with an inner wall of the bass reflex port and that extends outward in a circumferential direction from a second entrance on an opposite side of the bass reflex port to the first entrance; a second wall that defines a flow path for air passing through the inside of the bass reflex port between the second wall and an inner wall of the second guide portion; Equipped with a cross-sectional area of ​​an air flow path through the bass reflex port continuously increases from a position immediately before the first opening in the bass reflex port toward an outer end in the circumferential direction of the first guide portion, A bass reflex speaker, characterized in that a cross-sectional area of ​​an air flow path through the bass reflex port continuously increases from just before the second entrance in the bass reflex port toward the outside in the circumferential direction of the second guide portion.

5. A speaker housing; a bass reflex port disposed within the housing; a first guide portion having an inner wall continuous with an inner wall of the bass reflex port and extending outward in a circumferential direction from a first entrance in the housing of the bass reflex port, the first guide portion forming a flow path for air passing through the inside of the bass reflex port between the first entrance and a first wall facing the first entrance; a second guide portion having an inner wall continuous with the inner wall of the bass reflex port and extending outward in a circumferential direction from a second opening on the opposite side of the bass reflex port to the first opening, forming a flow path for air passing through the inside of the bass reflex port between the second opening and the second wall facing the second opening; Equipped with a cross-sectional area of ​​a first air flow path from the front of the first opening in the bass reflex port to the outside in the circumferential direction of the first opening increases continuously, and a cross-sectional area of ​​a second air flow path from the front of the second opening in the bass reflex port to the outside in the circumferential direction of the second opening increases continuously, the increase in cross-sectional area of ​​the first air flow passage is equal to the increase in cross-sectional area of ​​the second air flow passage; A bass reflex speaker characterized by the above.

6. A bass reflex speaker as described in claim 5, wherein a first wall opposite the first entrance / exit constitutes the housing.

7. A speaker housing; a bass reflex port disposed within the housing; a first guide portion having an inner wall continuous with an inner wall of the bass reflex port and extending outward in a circumferential direction from a first entrance in the housing of the bass reflex port, the first guide portion forming a flow path for air passing through the inside of the bass reflex port between the first entrance and a first wall facing the first entrance; a second guide portion having an inner wall continuous with the inner wall of the bass reflex port and extending outward in a circumferential direction from a second opening on the opposite side of the bass reflex port to the first opening, forming a flow path for air passing through the inside of the bass reflex port between the second opening and the second wall facing the second opening; Equipped with a cross-sectional area of ​​an air flow path through the bass reflex port continuously increases from a position immediately before the first opening in the bass reflex port toward an outer side in a circumferential direction of the first guide portion, a cross-sectional area of ​​an air flow path through the bass reflex port continuously increases from a position immediately before the second opening in the bass reflex port toward an outer side in a circumferential direction of the second guide portion, a distance between the first guide portion and the first wall is equal to a distance between the second guide portion and the second wall; A bass reflex speaker characterized by the above.

8. A bass reflex speaker as described in Claim 7, wherein a first wall opposite the first entrance / exit constitutes the housing.

9. A continuous increase in a cross-sectional area of ​​a first air flow path extending from just before the first entrance / exit in the bass reflex port toward the outside in the circumferential direction of the first guide portion is equal to a continuous increase in a cross-sectional area of ​​a second air flow path extending from just before the second entrance / exit in the bass reflex port toward the outside in the circumferential direction of the second guide portion.

9. The bass reflex speaker according to claim 7 or 8.

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