Acoustic waveguide

Abstract

The present invention relates to an acoustic waveguide for transferring a sound wave generated from a sound source into a free sound field and, more specifically, to an acoustic waveguide capable of increasing radiation efficiency and improving frequency spectrum flatness at sound pressure level (SPL) by providing a unique shape design in a width direction and a height direction for each of a linear waveguide and an L-shaped curved waveguide.

Description

acoustic waveguide

[0001] The present invention relates to an acoustic waveguide for transmitting sound waves generated from a sound source to a free sound field, and more particularly, to an acoustic waveguide capable of increasing sound radiation efficiency and improving sound pressure level (SPL) frequency spectrum flatness by providing a unique shape design in the width direction and height direction for each of a straight waveguide and an L-shaped bent waveguide.

[0002] There are various acoustic energy transmission devices around us in our daily lives, and these devices transmit energy by radiating it from the sound source inside the device into the free sound field through a waveguide, or by radiating it by having a diaphragm (membrane or thin plate) directly contact the free sound field, as in the case of a woofer.

[0003] Most electronic devices with built-in speakers, such as smartphones and monitors, radiate sound through waveguides. This creates a sound pressure level frequency spectrum characterized by peaks and dips due to resonance within the waveguide and the radiation impedance of the aperture. When the sound pressure level difference between peaks and dips in the frequency spectrum is significant, sounds at specific frequencies become significantly louder or quieter, degrading the device's audio quality.

[0004] Therefore, to solve these problems, acoustic energy transmission devices have been required to modulate the frequency spectrum, such as flattening the frequency spectrum or strengthening or weakening a specific frequency band, depending on the purpose.

[0005] [Prior Art Literature]

[0006] (Patent Document 1) Korean Patent Publication No. 10-2018-0054586 (published on May 24, 2018)

[0007] The present invention has been devised to solve the above problems, and the purpose of the present invention is to provide an acoustic waveguide capable of increasing sound radiation efficiency and improving sound pressure level frequency spectrum flatness by providing a unique shape design in the width direction and height direction for each of a straight waveguide and an L-shaped bent waveguide.

[0008] The present invention is an acoustic waveguide for transmitting sound waves, wherein the waveguide includes an inlet through which sound waves are incident, an outlet through which sound waves are radiated, and a duct connected from the inlet to the outlet to form a passage through which sound waves are propagated, and the duct may be configured such that the width of the passage narrows and then widens from the inlet to the outlet at least once.

[0009] The radiation efficiency and flatness of the sound pressure level frequency spectrum of sound waves radiated from the above outlet can be improved.

[0010] The above duct may be configured so that the width of the passage narrows and then widens from the inlet to the outlet at least once, but narrows again at the end.

[0011] The above duct may be configured so that the center line connecting the center of the passage from the inlet to the outlet is a straight line.

[0012] The above duct may be configured so that the width of the passage first narrows from the inlet.

[0013] The above duct includes an upper wall, a lower wall, a left wall, and a right wall forming the passage, and the left wall and the right wall can be configured to be symmetrical about the center line.

[0014] Among the narrowing parts of the above passage, the first narrowing part from the entrance is called the first concave part, and the distance from the entrance to the exit is In this case, the first concave portion is 0.1 and 0.5 It can be located in between.

[0015] The duct includes an upper wall, a lower wall, a left wall, and a right wall forming the passage, and the duct is a distance from any point on the center line to the left wall or the right wall. It can be configured to satisfy [Mathematical Formula 1] below.

[0016] [Mathematical Formula 1]

[0017]

[0018] (Here, is a natural number representing the number of types of trigonometric functions used in linear sums. is the length of the center line above, is a constant corresponding to the optimal value derived from is a constant that determines the width of the passage at the above entrance and exit.)

[0019] The above duct may be configured such that the center line connecting the center of the passage from the inlet to the outlet is a curved line, and the width of the passage narrows and then widens from the inlet to the outlet at least once.

[0020] The above duct may be configured so that the width of the passage first widens from the inlet.

[0021] Among the narrowing portions of the passage, the portion that first narrows from the entrance is called a first concave portion, and the first concave portion may be located adjacent to a corner where the center line is bent.

[0022] The duct includes an upper wall, a lower wall, an inner curved wall, and an outer curved wall forming the passage, and a point where a first tangent line in contact with an inlet portion of the inner curved wall and a second tangent line in contact with an outlet portion of the inner curved wall intersect is called a tangent intersection point, and the distance from the inlet to the tangent intersection point is , and the distance from the above exit to the above tangent intersection In this case, the first concave portion is 0.5 from the entrance. Ideally spaced, 0.5 from the above exit The ideal can be positioned spaced apart.

[0023] The above duct may be configured so that the width of the passage first narrows from the inlet.

[0024] The duct includes an upper wall, a lower wall, an inner curved wall, and an outer curved wall forming the passage, and the duct has a distance between the inner curved wall and the outer curved wall. It can be configured to satisfy [Mathematical Formula 2] below.

[0025] [Equation 2]

[0026]

[0027] (Here, is a constant corresponding to the derived optimal value, is a constant that determines the width of the passage at the above entrance and exit.)

[0028] The above duct may be configured so that the height of the passage is constant from the inlet to the outlet.

[0029] The above duct may be configured such that the height of the passageway varies from the inlet to the outlet.

[0030] The duct may be configured such that the height of the passage increases continuously or stepwise, or decreases continuously or stepwise.

[0031] The above duct has a height of the passage from the inlet to the outlet. It is configured to change in stages, and the above During the translation stage The height of the passage in the second stage is can satisfy [Mathematical Formula 3] below.

[0032] [Equation 3]

[0033]

[0034] (Here, is the height of the passage at the above entrance, is the height of the passage at the above exit, is the number of parts with different heights, Is Any natural number below.)

[0035] According to the present invention, by providing a unique shape design in the width direction and height direction for each of a straight waveguide and an L-shaped waveguide, it is possible to increase sound radiation efficiency and improve sound pressure level frequency spectrum flatness.

[0036] In addition, the waveguide of the present invention is designed to have a narrowing portion, so that a thermal viscosity loss effect occurs, which can further improve the flatness of the sound pressure level frequency spectrum.

[0037] In addition, it is possible to design the tube in various shapes without significantly increasing the volume occupied by the waveguide, so it can be easily applied to waveguides connected to existing speakers.

[0038] Figure 1 is a perspective view schematically illustrating a conventional waveguide.

[0039] Fig. 2 is a perspective view showing a waveguide according to the first embodiment of the present invention.

[0040] Figure 3 is a cross-sectional view of Figure 2.

[0041] FIG. 4 is a graph and table showing the frequency spectrum and performance of a waveguide according to the first embodiment of the present invention.

[0042] FIG. 5 is a graph and table showing the frequency spectrum and performance of a waveguide according to some embodiments of the present invention.

[0043] Figure 6 is a perspective view and a cross-sectional view showing a modified example of the first embodiment of the present invention.

[0044] Figure 7 is a perspective view and a cross-sectional view showing a modified example of the first embodiment of the present invention.

[0045] Figure 8 is a perspective view and a cross-sectional view showing a modified example of the first embodiment of the present invention.

[0046] FIG. 9 is a graph and table showing the frequency spectrum and performance according to some embodiments of the present invention.

[0047] Fig. 10 is a cross-sectional view showing the direction of sound wave propagation in a waveguide according to the second embodiment of the present invention.

[0048] Figure 11 is a drawing for explaining Figure 10 in detail.

[0049] FIG. 12 is a graph and table showing the frequency spectrum and performance of a waveguide according to the second embodiment of the present invention.

[0050] Fig. 13 is a perspective view and a cross-sectional view showing a waveguide according to a modified example of the second embodiment of the present invention.

[0051] FIG. 14 is a graph and table showing the frequency spectrum and performance of a waveguide according to a modified example of the second embodiment of the present invention.

[0052] Fig. 15 is a side cross-sectional view showing the change in height of a waveguide according to the third embodiment of the present invention.

[0053] Fig. 16 is a graph showing the frequency spectrum of a waveguide according to the third embodiment of the present invention.

[0054] Fig. 17 is a perspective view showing the change in height of a waveguide according to the fourth embodiment of the present invention.

[0055] Hereinafter, the present invention will be described with reference to the attached drawings.

[0056] FIG. 2 is a perspective view showing an acoustic waveguide according to the first embodiment of the present invention, and FIG. 3 is a cross-sectional view of FIG. 2.

[0057] Referring to FIGS. 2 and 3, an acoustic waveguide according to an embodiment of the present invention includes an inlet (100) through which sound waves are incident, an outlet (200) through which sound waves are radiated, and a duct (300) forming a passage (600) through which sound waves can be incident at the inlet (100) and propagate to the outlet (200). A sound source radiating sound waves may be placed around or within the inlet. Sound waves radiated from the sound source are incident at the inlet (100), the incident sound waves are propagated along the passage (600) of the duct (300), and the propagated sound waves are radiated at the outlet (200). The sound waves are radiated into a free sound field through the outlet (200), thereby transmitting acoustic energy.

[0058] Hereinafter, the duct (300) will be described in detail. Here, a passage (600) through which sound waves are transmitted is formed inside the duct (300), and the height of the passage is At this time, the width of the entrance is and the width of the exit is It may be equal to, or smaller than, or larger than. Here, an imaginary line connecting the center of the inlet (100) to the center of the outlet (200) is called a center line (C). The triangular arrow drawn on the center line (C) indicates the direction of sound wave propagation in the passage (600).

[0059] The duct (300) is configured to be surrounded by a plurality of wall surfaces to form a passage (600) inside. That is, a hollow portion is formed by the plurality of surrounded wall surfaces, and the hollow portion is used as a passage (600) through which sound waves propagate.

[0060] The duct (300) has a width of the passage (600) ) is configured to continuously change from the inlet (100) to the outlet (200) along the center line (C) and to repeat the process of narrowing and widening from the inlet (100) to the outlet (200) at least once. In more detail, the duct (300) is configured to have a width ( ) may be configured to narrow and widen repeatedly along the center line (C) from the inlet (100) to the outlet (200), and finally narrow again when reaching the outlet (200).

[0061] Next, the shape of the center line (C) will be described with reference to FIG. 3. According to one embodiment of the present invention, the duct (300) can be configured so that the center line (C) is a straight line. Compared to the conventional waveguide of FIG. 1(a), the waveguide according to one embodiment of the present invention is configured so that the direction of propagation of sound waves is a straight line, which is the same as the conventional straight waveguide, and therefore provides an advantage in that the conventional straight waveguide can be easily replaced with the waveguide according to one embodiment of the present invention.

[0062] In addition, the waveguide according to one embodiment of the present invention can increase sound radiation efficiency without significantly changing the area and volume occupied by the conventional straight waveguide of Fig. 1(a), and thus can be easily applied to a waveguide connected to an existing speaker.

[0063] Here, if the center line (C) becomes a straight line, the duct (300) has a width of the passage ( ) can be configured to first narrow along the center line (C) from the entrance (100). The width of the passage ( ) can be configured to narrow the sound pressure level at the peak of the sound pressure level frequency spectrum according to the thermal viscosity loss effect, and the frequency spectrum can be further flattened.

[0064] Next, a description will be given of a concave portion, which is a portion where the width of the passage (600) is narrowed and formed concavely. A concave portion refers to an inflection point where the width of the passage (600) narrows and then widens, i.e., a portion where the width is formed concavely and narrower than the surrounding area. According to one embodiment of the present invention, the width of the passage (600) can be configured to narrow and then widen at least once, and thus at least one concave portion can be formed. At this time, among the concave portions formed at least once, the portion that first narrows from the entrance (100) is referred to as a first concave portion (500).

[0065] The distance from the entrance (100) to the exit (200) In this case, the first concave part is 0.1 and 0.5 can be located between 0.1 here The corresponding position is 0.1 along the center line (C) from the entrance (100). It is located at a distance of the length, 0.5 The corresponding position is 0.5 along the center line (C) from the entrance (100). It is located at a distance of that length.

[0066] Next, a description will be given of a plurality of walls surrounding a duct (300) and forming a passage (600). The duct (300) may be configured to be surrounded by an upper wall, a lower wall, a left wall (310), and a right wall (320). At this time, as illustrated in FIG. 3, the left wall (310) and the right wall (320) may be formed in a wave shape, and are configured so that the width of the passage (600) can be narrowed and then widened at least once.

[0067] At this time, one embodiment of the present invention is not limited to a configuration in which the left and right walls are formed in a wave shape and the width changes continuously, and may be formed in a shape that changes stepwise so that the width changes stepwise.

[0068] In addition, the left wall (310) and the right wall (320) may be configured symmetrically with respect to the center line (C), but are not limited thereto, and the left wall (310) and the right wall (320) may be configured as walls having different wave shapes or shapes that change in steps, and any wall of the left wall (310) or the right wall (320) may be configured as a wall having a straight shape.

[0069] As another example, the distance from any point on the center line (C) to the left wall (310) or the right wall (320) It can be configured to satisfy [Mathematical Formula 1] below.

[0070] [Mathematical Formula 1]

[0071]

[0072] (Here, is a natural number representing the number of types of trigonometric functions used in linear sums. is the length of the center line above, is a constant corresponding to the optimal value derived from is a constant that determines the width of the passage at the above entrance and exit.)

[0073] The above [Mathematical Formula 1] is not limited to the form of a linear sum of trigonometric functions, and the width of the passage (600) at the entrance (100) and the exit (200) ) can also be applied in other cases. In addition, since the above [Mathematical Formula 1] follows the linear sum of trigonometric functions, the length of the conventional waveguide of Fig. 1(a) and the waveguide according to the embodiment of the present invention ( ) are the same, the area of ​​the waveguide according to the embodiment of the present invention and the conventional waveguide can be configured to be the same despite the change in the width of the waveguide according to the embodiment of the present invention. Therefore, there is an advantage in that the sound radiation efficiency can be increased without significantly changing the area and volume occupied by the conventional straight waveguide, and thus it can be easily applied to existing speakers.

[0074] Referring to FIG. 4, flattening of the sound pressure level frequency spectrum according to one embodiment of the present invention is described.

[0075] Fig. 4(a) is a graph showing the sound pressure level frequency spectrum of a conventional waveguide (1) and the sound pressure level frequency spectrum of a waveguide according to an embodiment of the present invention (1000), and Fig. 4(b) is a table showing the average sound pressure level and standard deviation increase / decrease compared to the conventional waveguide (1).

[0076] An acoustic waveguide according to one embodiment of the present invention provides an advantage of improving acoustic radiation performance by flattening the sound pressure level frequency spectrum of sound waves radiated from an outlet. Here, flattening the frequency spectrum means flattening the spectrum by reducing the sound pressure level at the peak or increasing the sound pressure level at the dip in the sound pressure level frequency spectrum having peaks and dips due to the influence of the resonance phenomenon within the waveguide and the radiation impedance of the opening.

[0077] Peak refers to the part where the sound pressure level increases and then decreases as the frequency increases, i.e., the peak part of the graph shape shown in Fig. 4(a). Dip refers to the part where the sound pressure level decreases and then increases, i.e., the downward-sloping part of the graph shape shown in Fig. 4.

[0078] Referring to FIG. 4(a), the sound pressure level frequency spectrum of the waveguide (1000) according to one embodiment of the present invention is shown in "Case 1", and the sound pressure level frequency spectrum of the conventional waveguide (1) is shown in "Reference". It can be confirmed that the sound pressure level of the waveguide (1000) according to one embodiment of the present invention is improved in the frequency band corresponding to the dip compared to the conventional waveguide (1).

[0079] In addition, referring to FIG. 4(b), it can be confirmed that the waveguide (1000) according to one embodiment of the present invention has an increased average sound pressure level (increased by about 5.1 dB) and a decreased standard deviation (decreased by about 2.4 dB) in the target frequency band compared to a conventional straight waveguide corresponding to a conventional waveguide (1).

[0080] In this way, the waveguide (1000) according to one embodiment of the present invention exhibits a flattened sound pressure level frequency spectrum by improving the sound pressure level in the dip band compared to the conventional waveguide (1), which can also be confirmed by an increase in the average sound pressure level and a decrease in the standard deviation. Therefore, the waveguide according to one embodiment of the present invention can flatten the sound pressure level frequency spectrum and provide the advantages of increased sound radiation efficiency and improved sound quality.

[0081] Next, the effect of a waveguide according to one embodiment of the present invention for a target frequency range will be described with reference to FIG. 5.

[0082] FIG. 5(a) is a graph showing the sound pressure level frequency spectrum of a waveguide according to one embodiment of the present invention in comparison with a conventional waveguide (1) according to a target frequency band, and FIG. 5(b) is a table showing the average sound pressure level and standard deviation increase / decrease compared to the conventional waveguide (1).

[0083] Referring to FIG. 5(a), the sound pressure level frequency spectrum of one embodiment of the present invention designed to increase the average sound pressure level in the 3 kHz - 10 kHz frequency band is shown as "M=2(3-10 kHz)", the sound pressure level frequency spectrum of one embodiment of the present invention designed to increase the average sound pressure level in the 3 kHz - 15 kHz frequency band is shown as "M=2(3-15 kHz)", and the sound pressure level frequency spectrum of the conventional waveguide (1) is shown in "Reference".

[0084] It can be confirmed that the waveguide according to one embodiment of the present invention has a higher sound pressure level in the dip band than the conventional waveguide (1) for each target frequency band range.

[0085] Although Fig. 5(a) shows two frequency band ranges of 3 kHz - 10 kHz and 3 kHz - 15 kHz, the acoustic waveguide according to one embodiment of the present invention is not limited to the corresponding frequency band range, and can be applied to the audible frequency band range or other band ranges.

[0086] In addition, referring to FIG. 5(b), it can be confirmed that the waveguide (1000) according to one embodiment of the present invention has an increased average sound pressure level in the target frequency band and a decreased standard deviation compared to a conventional straight waveguide corresponding to a conventional waveguide (1).

[0087] In this way, the waveguide (1000) according to one embodiment of the present invention has a flattened sound pressure level frequency spectrum compared to the conventional waveguide (1), and provides the advantages of increased sound radiation efficiency and improved sound quality.

[0088] Next, various modifications according to one embodiment of the present invention will be described with reference to FIGS. 6 to 8.

[0089] Fig. 6(a) is a perspective view showing a waveguide when the left wall (310) and the right wall (320) satisfy the above-described [Mathematical Formula 1], and Fig. 6(b) is a cross-sectional view of Fig. 6(a). In Fig. 6 The case where the value is 3 is shown, but it is not limited to this. The value can be any of a variety of other constant values.

[0090] Figure 7 is a diagram showing the width at the entrance (100) of one embodiment of the present invention. ) and width at the exit (200) ) shows a modified example of this change.

[0091] As shown in Fig. 7, if the width of the passage (600) is repeated to narrow and widen at least once, the above-described effect of the present invention can be implemented, and the widths of the inlet (100) and the outlet (200) are not limited to the case where they are the same, but can also be applied to cases where the widths of the inlet (100) and the outlet (200) are different.

[0092] Furthermore, Fig. 8 shows the width at the entrance (100) of one embodiment of the present invention. ) and width at the exit (200) ) is different, and a modified example is shown in which the shapes of the left wall (310) and the right wall (320) are different.

[0093] As shown in Fig. 8, even if the shapes of the left wall (310) and the right wall (320) are not symmetrical but different, if the width of the passage (600) is repeated to narrow and widen at least once, the effect of the present invention can be implemented in the same manner.

[0094] In this way, the left wall (310) and the right wall (320) are designed in various ways to increase the passage width of the duct (300). ) can be configured to narrow and widen at least once. In this way, the present invention has the advantage of being able to provide a waveguide having various shapes while also providing a waveguide having improved sound radiation performance.

[0095] Fig. 9(a) is a graph showing the frequency spectrum of a waveguide according to one embodiment of the present invention according to the thermal viscous loss effect, and Fig. 9(b) is a table showing the increase or decrease in the standard deviation of the sound pressure level when the thermal viscous loss effect is taken into account.

[0096] Typically, as the width of a waveguide narrows, acoustical viscous losses occur, which degrade the performance of the waveguide. However, a waveguide according to one embodiment of the present invention can improve the flatness of the frequency spectrum by utilizing the viscous thermal losses in the concave portion where the width of the passage narrows.

[0097] That is, as illustrated in Fig. 9(a), when considering the thermal viscous loss effect, it can be confirmed that the peak portion of the graph is reduced in the waveguide according to an embodiment of the present invention. In addition, as illustrated in Fig. 9(b), when considering the thermal viscous loss effect, the standard deviation of the sound pressure level is reduced (approximately 3.5 dB reduction).

[0098] Therefore, the waveguide according to one embodiment of the present invention utilizing the thermal viscosity loss effect can provide the advantage of reducing the sound pressure level value corresponding to the peak, thereby flattening the frequency spectrum and improving sound quality.

[0099] Figure 10 is a schematic diagram of an acoustic waveguide according to a second embodiment of the present invention.

[0100] First, the shape of the duct (300) of the acoustic waveguide according to the second embodiment will be described. As illustrated in FIG. 10, the shape of the duct (300) can be configured so that the center line (C) is a curved shape. Here, the center line (C) refers to an imaginary line that starts from the center of the inlet (100), extends along the direction of travel of the passage (600), and connects to the center of the outlet (200). The triangular arrow depicted on the center line (C) indicates the direction of travel of sound waves in the passage (600).

[0101] According to the second embodiment of the present invention, the duct can be configured so that the width of the passage (600) along the curved center line (C) widens and narrows from the inlet (100) to the outlet (200) at least once. More specifically, the duct has a width of the passage (600) ) may be configured to narrow and then widen at least once, but to narrow again at the end near the exit (200).

[0102] In this way, the width of the passage (600) ) is changed, but the direction of travel of the passage (600) is made to be curved, so that the conventional curved waveguide of Fig. 1(b) can be easily replaced with the waveguide according to the second embodiment of the present invention. In addition, the waveguide according to the second embodiment of the present invention can increase sound radiation efficiency without significantly changing the area and volume occupied by the conventional curved waveguide of Fig. 1(b), so that it can be easily applied to a waveguide connected to an existing speaker.

[0103] Area A illustrated in Fig. 10 represents a portion where the center line (C) is bent. Although Fig. 10 illustrates an acoustic waveguide in which the center line (C) is bent once, the embodiment of the present invention is not limited thereto, and a plurality of ducts in which the center line (C) is bent once may be configured to be sequentially extended and connected, and thus may be similarly applied to an acoustic waveguide in which the center line (C) is bent multiple times.

[0104] In more detail, if the center line (C) is a curved line, the duct (300) has a width ( ) can be formed to first widen along the center line (C) from the entrance (100). At this time, the width of the passage (600) ) is a part that first narrows from the entrance (100) and then widens again to become concave, and is called a first concave part (500), and the first concave part can be formed adjacent to a corner part where the center line (C) is bent.

[0105] Next, the position of the first concave portion (500) will be described in detail with reference to Fig. 11. Fig. 11(a) is a drawing for explaining the position of the first concave portion (500), and Fig. 11(b) is a drawing that enlarges area B of Fig. 11(a) for explaining the position of the first concave portion (500) in detail.

[0106] The duct (300) includes an upper wall, a lower wall, an inner curved wall (330), and an outer curved wall (340) forming a passage (600). Here, a line where the inner curved wall (330) contacts the inlet (100) is referred to as a first tangent line (T1), and a line where the inner curved wall (330) contacts the outlet (200) is referred to as a second tangent line (T2). At this time, the point where the first tangent line (T1) and the second tangent line (T2) intersect is referred to as a tangent intersection point (P), and the distance from the inlet (100) to the tangent intersection point (P) is referred to as , and the distance from the exit (200) to the tangent intersection point (P) It is said.

[0107] The B region shown in Fig. 11(a) is 0.5 from the inlet (100) among the entire waveguide according to the second embodiment of the present invention. 0.5 from the exit (200) from the separated part This is the area that displays the separated parts.

[0108] Figure 11(b) is an enlarged drawing of the above-described area B, and referring to Figure 11(b), the width of the passage (600) ) is formed within the B region, which is a first concave portion (500) that is formed by narrowing and then widening again and becoming concave. In this way, the first concave portion can be formed adjacent to the corner portion where the center line (C) is bent, and more specifically, the first concave portion (500) is formed at a distance of 0.5 from the entrance (100). More than 0.5 meters from the exit It can be formed to be spaced apart by more than a distance.

[0109] In this way, by forming the first concave portion (500) adjacent to the corner portion where the center line (C) is bent, a waveguide having increased sound radiation efficiency and a flattened sound pressure level frequency spectrum is provided compared to an existing waveguide, thereby improving the sound quality of the waveguide.

[0110] More specifically, according to the transfer function theory, the acoustic properties in a waveguide are determined by the area of ​​the cross-section perpendicular to the direction in which the sound waves propagate, so the distance between the inner curved wall (330) and the outer curved wall (340) It can be configured to satisfy [Mathematical Formula 2] below.

[0111] [Equation 2]

[0112]

[0113] (Here, is a constant corresponding to the derived optimal value, is a constant that determines the width of the passage at the above entrance and exit.)

[0114] Next, the frequency spectrum and flattening of the frequency spectrum of the waveguide according to the second embodiment of the present invention will be described with reference to FIG. 12.

[0115] Fig. 12(a) is a graph showing the sound pressure level frequency spectrum for a conventional waveguide (2) and the second embodiment of the present invention. The sound pressure level frequency spectrum of the conventional waveguide (2) is shown as "Reference", and the sound pressure level frequency spectrum of the waveguide according to the embodiment of the present invention is shown as "Case 2". As shown in Fig. 12(a), it can be confirmed that the sound pressure level in the dip band has increased compared to the conventional waveguide (2). Since the sound pressure level in the dip band has an increased frequency spectrum, it is possible to improve the flatness of the frequency spectrum while increasing the sound radiation efficiency.

[0116] Fig. 12(b) is a table showing the average sound pressure level and area change rate in the frequency spectrum band of the waveguide according to the second embodiment of the present invention compared to the conventional waveguide (2). Referring to Fig. 12(b), it can be confirmed that, compared to the conventional waveguide (2), in the case of the second embodiment of the present invention, the average sound pressure level increases (about 4.8 dB increase) in the target frequency band range, and the area increase rate is only 1.7%.

[0117] In this way, according to one embodiment of the present invention, a flattened sound pressure level frequency spectrum is provided compared to a conventional waveguide along with an increase in the average sound pressure level, thereby providing the advantage of improved sound quality.

[0118] In addition to improving sound quality, since the rate of change in area is not large compared to a conventional waveguide (2), it is possible to design the tube in various shapes without significantly increasing the volume occupied by the conventional waveguide, and it provides the advantage of being easily applicable to waveguides connected to conventional speakers.

[0119] Fig. 13 is a perspective view and a cross-sectional view illustrating a modified example of the second embodiment of the present invention. Referring to Fig. 13, the duct can be configured so that the width of the passage (600) along the curved center line (C) narrows and then widens from the inlet (100) to the outlet (200) at least once. More specifically, the duct (300) has a width ( ) may be configured to first narrow from the entrance (100).

[0120] This is similar to the first embodiment described above, the width of the passage ( ) can be configured to narrow the sound pressure level at the peak of the sound pressure level frequency spectrum according to the thermal viscosity loss effect, and the frequency spectrum can be further flattened.

[0121] FIG. 14 is a graph and table showing the sound pressure level frequency spectrum of a waveguide according to a modified example of the second embodiment of the present invention.

[0122] Referring to Fig. 14(a), the sound pressure level frequency spectrum of a waveguide (1000) according to a modified example of the second embodiment of the present invention is shown in "Case 2'" of Fig. 14(a), and the sound pressure level frequency spectrum of a conventional waveguide (2) is shown in "Reference". It can be confirmed that, compared to the conventional waveguide (2), the waveguide (1000) according to an embodiment of the present invention exhibits a frequency spectrum in which the sound pressure level in the dip band is improved. In this way, by improving the sound pressure level in the dip band, the sound radiation efficiency is increased, and the advantages of flattening the frequency spectrum and improving sound quality are provided.

[0123] Next, referring to FIG. 14(b), it can be confirmed that the waveguide according to the embodiment of the present invention has an increased band average sound pressure level (increase of about 5.8 dB) and a decreased standard deviation (decrease of about 1.9 dB) compared to the conventional waveguide (2). Thus, it can be confirmed that the waveguide according to the embodiment of the present invention has a flattened sound pressure level frequency spectrum compared to the conventional waveguide.

[0124] In addition, it provides the advantage that the area occupied is reduced compared to the conventional waveguide (2), so that the waveguide connected to the existing speaker can be easily replaced with the waveguide according to one embodiment of the present invention.

[0125] Next, an acoustic waveguide according to a third embodiment of the present invention will be described with reference to FIG. 15.

[0126] Fig. 15 is a schematic diagram showing the internal shape of a passage of an acoustic waveguide according to a third embodiment of the present invention.

[0127] As shown in Fig. 15, the acoustic waveguide according to the third embodiment of the present invention is configured such that the propagation path of sound waves is a straight line, i.e., the center line (C) is a straight line, and the height changes. As described above, an imaginary line connecting the center of the inlet (100) to the center of the outlet (200) is referred to as the center line (C), and a triangular arrow drawn on the center line (C) indicates the direction of propagation of sound waves in the passage (600).

[0128] FIG. 15(a) to FIG. 15(d) are cross-sectional views showing changes in the height of a waveguide according to a third embodiment of the present invention. The height of the passage (600) may increase stepwise as in FIG. 15(a), may increase continuously as in FIG. 15(b), may decrease stepwise as in FIG. 15(c), or may decrease continuously as in FIG. 15(d). However, these only illustrate some examples of changes in the height of the passage, and the embodiments of the present invention are not limited to the examples illustrated in the drawings.

[0129] In more detail, the height ( ) in cases where it changes step by step, When the height changes in steps Height of the passage in the second stage can be configured to satisfy [Mathematical Formula 3] below.

[0130] [Equation 3]

[0131]

[0132] (Here, is the height of the passage at the above entrance, is the height of the passage at the above exit, is the number of parts with different heights, Is Any natural number below.)

[0133] The above [Mathematical Formula 3] is an equation that expresses the Chebyshev height distribution, and is the height of the passage of the waveguide according to one embodiment of the present invention. ) can be configured to satisfy the height distribution described above.

[0134] Fig. 16 is a graph showing the sound pressure level frequency spectrum of a conventional waveguide (1) and a waveguide having a Chebyshev height distribution according to an embodiment of the present invention. The conventional waveguide (1) having an arbitrary height variation is shown in "Reference," and the waveguide according to an embodiment of the present invention is shown in "Case 3."

[0135] Referring to Fig. 16, by providing a waveguide having such a height distribution, the reflection rate due to the change in cross-sectional area can be reduced, and the effect of increasing the radiation efficiency in the dip band can be obtained compared to when there is a duct having an arbitrary height between ducts having different heights.

[0136] In this way, some embodiments of the present invention provide the advantage of being able to flatten the sound pressure level frequency spectrum even when the height of the passage changes from the inlet to the outlet.

[0137] Fig. 17 is a drawing showing a fourth embodiment of the present invention, in which the propagation path of sound waves is not a straight line but a bent shape, that is, the center line (C) is bent, and the height of the passage of the duct (300) is configured to change. As described above, an imaginary line connecting the center of the inlet (100) to the center of the outlet (200) is referred to as the center line (C), and a triangular arrow drawn on the center line (C) indicates the direction of propagation of sound waves in the passage (600).

[0138] The feature of the third embodiment of the present invention described above, in which the height of the passage is configured to change, can be applied not only when the propagation path of the sound wave is straight, but also when the propagation path of the sound wave is bent.

[0139] Fig. 18(a) is a graph showing the sound pressure level frequency spectrum when the fourth embodiment of the present invention satisfies the Chebyshev height distribution of [Mathematical Formula 3] above, compared to that of a conventional waveguide (2), and Fig. 18(b) is a graph showing an enlarged area D of Fig. 18(a). The waveguide according to one embodiment of the present invention is shown in "Case 4", and the conventional waveguide (2) is shown in "Reference".

[0140] Referring to Fig. 18(b), it can be confirmed that the sound pressure level in the dip band, where the sound pressure level decreases and then increases, increases, thereby confirming that the sound radiation efficiency is increased.

[0141] That is, by providing a waveguide having such a height distribution, the reflection rate due to the change in cross-sectional area can be reduced, and the effect of increasing the radiation efficiency in the dip band can be obtained compared to when there is a duct having an arbitrary height between ducts having different heights.

[0142] While the embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical concept or essential features thereof. Therefore, the embodiments described above should be understood to be illustrative in all respects and not restrictive.

[0143] [Explanation of symbols]

[0144] 1000(1001,1002,1003,1004): Waveguide

[0145] 100: Entrance

[0146] 200: Exit

[0147] 300: Duct

[0148] 500: First concave

[0149] 600: Passage

[0150] 310: Left wall

[0151] 320: Right wall

[0152] 330: Inner curved wall

[0153] 340: Outer curved wall

[0154] C: Center line

[0155] H: Height of the passage

[0156] W: width of the passage

[0157] T1: First tangent

[0158] T2: Second tangent

[0159] P: Tangent intersection point

Claims

1. As an acoustic waveguide that transmits sound waves, The above waveguide includes an inlet through which sound waves are incident, an outlet through which sound waves are radiated, and a duct that is connected from the inlet to the outlet and forms a path through which sound waves propagate. The above duct is configured so that the width of the passage narrows and widens from the inlet to the outlet at least once. Acoustic waveguide.

2. In paragraph 1, To improve the radiation efficiency of sound waves radiated from the above outlet and the flatness of the sound pressure level frequency spectrum, Acoustic waveguide.

3. In paragraph 1, The above duct is configured such that the width of the passage narrows and widens from the inlet to the outlet at least once, but narrows again at the end. Acoustic waveguide.

4. In paragraph 3, The above duct is configured so that the center line connecting the center of the passage from the inlet to the outlet is a straight line. Acoustic waveguide.

5. In paragraph 4, The above duct is configured so that the width of the passage first narrows from the inlet. Acoustic waveguide.

6. In paragraph 5, The duct includes an upper wall, a lower wall, a left wall, and a right wall forming the passage, The left and right walls are configured to be symmetrical with respect to the center line. Acoustic waveguide.

7. In paragraph 5, Among the narrowing parts of the above passage, the first narrowing part from the entrance is called the first concave part. The distance from the above entrance to the exit If so, The above first concave portion is 0.1 and 0.5 Located between, Acoustic waveguide.

8. In paragraph 4, The duct includes an upper wall, a lower wall, a left wall, and a right wall forming the passage, The above duct is the distance from any point on the center line to the left wall or right wall It is configured to satisfy [Mathematical Formula 1] below, Acoustic waveguide. [Mathematical Formula 1] (Here, is a natural number representing the number of types of trigonometric functions used in linear sums. is the length of the center line above, is a constant corresponding to the optimal value derived from is a constant that determines the width of the passage at the above entrance and exit.) 9. In paragraph 1, The above duct is configured such that the center line connecting the center of the passage from the inlet to the outlet is a curved line, and the width of the passage narrows and widens from the inlet to the outlet at least once. Acoustic waveguide.

10. In paragraph 9, The above duct is configured so that the width of the passage first widens from the inlet. Acoustic waveguide.

11. In paragraph 10, Among the narrowing parts of the above passage, the first narrowing part from the entrance is called the first concave part. The above first concave portion is located adjacent to the corner where the center line is bent, Acoustic waveguide.

12. In paragraph 11, The duct includes an upper wall, a lower wall, an inner curved wall, and an outer curved wall forming the passage, The point where the first tangent line that is in contact with the entrance portion of the inner curved wall and the second tangent line that is in contact with the exit portion of the inner curved wall intersect is called the tangent intersection point, and the distance from the entrance to the tangent intersection point is , and the distance from the above exit to the above tangent intersection If you say so, The above first concave portion is 0.5 from the inlet Ideally spaced, 0.5 from the above exit Positioned ideally apart, Acoustic waveguide.

13. In paragraph 9, The above duct is configured so that the width of the passage first narrows from the inlet. Acoustic waveguide.

14. In paragraph 9, The duct includes an upper wall, a lower wall, an inner curved wall, and an outer curved wall forming the passage, The above duct is the distance between the inner curved wall and the outer curved wall It is configured to satisfy [Mathematical Formula 2] below, Acoustic waveguide. [Equation 2] (Here, is a constant corresponding to the derived optimal value, is a constant that determines the width of the passage at the above entrance and exit.) 15. In paragraph 1, The above duct is configured so that the height of the passage is constant from the inlet to the outlet. Acoustic waveguide.

16. In paragraph 1, The above duct is configured so that the height of the passage changes from the inlet to the outlet. Acoustic waveguide.

17. In paragraph 16, The above duct is configured so that the height of the passage increases continuously or stepwise, or decreases continuously or stepwise. Acoustic waveguide.

18. In paragraph 17, The above duct has a height of the passage from the inlet to the outlet. It is configured to change in stages, Above During the translation stage The height of the passage in the second stage is satisfying [Mathematical Formula 3] below, Acoustic waveguide. [Equation 3] (Here, is the height of the passage at the above entrance, is the height of the passage at the above exit, is the number of parts with different heights, Is Any natural number below.)

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