Noise control device
The sound emission control device addresses frequency variations in multi-directional sound propagation by using inlets, outlets, and horn-shaped guides to maintain consistent directivity, improving sound quality for both performers and distant listeners.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- YAMAHA CORP
- Filing Date
- 2022-03-08
- Publication Date
- 2026-07-23
AI Technical Summary
Existing acoustic devices that emit sound in multiple directions suffer from varying frequency characteristics due to sound propagation through multiple paths with different reflection points, leading to large peaks and dips in sound quality as the listener's head position changes.
A sound emission control device with multiple inlets, outlets, and horn-shaped guides that guide sound emitted from a vibrating surface to specific outlets, maintaining consistent directivity and reducing frequency variations.
The device provides high-quality sound with uniform frequency characteristics regardless of the listener's position, enhancing sound quality for both the performer and distant listeners by minimizing peaks and dips.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to a sound emission control device in an acoustic device that emits sound generated by a sound source in a plurality of directions.
Background Art
[0002] An acoustic device that emits sound generated from a common sound source in a plurality of directions is known. For example, Patent Document 1 discloses an electronic musical instrument provided with a diffuser that branches the sound emitted from a speaker to the front side and the back side of the electronic musical instrument.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] However, in the electronic musical instrument disclosed in Patent Document 1, the sound emitted from the speaker and branched by the diffuser spreads over a wide range and propagates through a plurality of paths with different reflection points. Therefore, when the listener's head moves, there is a problem that the frequency characteristics of the sound heard by the listener change depending on the position of the head. In addition, since sounds passing through a plurality of paths with different reflection points reach the listener's head, there is a problem that large peaks and dips occur in the frequency characteristics of the sound heard by the listener.
[0005] This invention has been made in view of the circumstances described above, and an object thereof is to improve the sound quality of the sound provided by an acoustic device that emits sound in a plurality of directions.
Means for Solving the Problems
[0006] This invention provides a sound emission control device having a plurality of inlets connected to branching sections facing a vibrating surface within an acoustic device, a plurality of outlets provided in the acoustic device and facing in different directions from one another, and a horn-shaped inner wall surrounding the space from each inlet to outlet, and having a plurality of guides that guide the sound emitted from the vibrating surface and branched by the branching sections to the plurality of outlets. [Brief explanation of the drawing]
[0007] [Figure 1] This is a perspective view showing the configuration of an electronic piano equipped with a sound emission control device, which is one embodiment of this invention. [Figure 2] This is an assembly diagram of the noise control device. [Figure 3] This is a perspective view of the noise control device. [Figure 4] Figure 3 shows a cross-sectional view along the line Ia-Ia'. [Figure 5] Figure 3 shows a cross-sectional view along the line Ib-Ib'. [Figure 6] This is a plan view illustrating the effects of the same embodiment. [Figure 7] A perspective view showing the configuration of another digital piano equipped with the same sound emission control device. [Figure 8] This is a perspective view showing other forms of electronic pianos. [Figure 9] This is a cross-sectional view taken along the line I-I' in Figure 8. [Modes for carrying out the invention]
[0008] Embodiments of this invention will be described below with reference to the drawings. Figure 1 is a perspective view showing the configuration of an electronic piano 100 equipped with sound emission control devices 10L and 10R, which is one embodiment of the present invention. As shown in Figure 1, two speakers 110L and 110R are positioned side by side near the top surface inside the housing of the electronic piano 100, with their vibrating surfaces facing upward. These speakers 110L and 110R are high-frequency speakers driven by sound signals generated based on keyboard playing.
[0009] Near the top of the front of the Electronic Piano 100's casing, there are two rectangular sound vents, 2FL and 2FR, arranged side by side. Additionally, near the top of the rear of the Electronic Piano 100's casing, there are two rectangular sound vents, 2BL and 2BR, arranged side by side.
[0010] Here, the centers of speaker 110L, sound outlets 2FL and 2BL are located at the same position in the left-right direction. Similarly, the centers of speaker 110R, sound outlets 2FR and 2BR are located at the same position in the left-right direction. Furthermore, the distance from the center of speaker 110L to the center of sound outlet 2FL is the same as the distance from the center of speaker 110L to the center of sound outlet 2BL. Also, the distance from the center of speaker 110R to the center of sound outlet 2FR is the same as the distance from the center of speaker 110R to the center of sound outlet 2BR.
[0011] In this embodiment, the electronic piano 100 is provided with a sound emission control device 10L inside its casing that branches the sound emitted from the vibrating surface of the speaker 110L and guides it in both directions toward the sound emission holes 2FL and 2BL. Furthermore, the electronic piano 100 is provided with a sound emission control device 10R inside its casing that branches the sound emitted from the vibrating surface of the speaker 110R and guides it in both directions toward the sound emission holes 2FR and 2BR. In the following, the configuration of each part of the electronic piano 100 will be described assuming an X-axis oriented in the left-right direction, a Y-axis oriented in the front-back direction, and a Z-axis oriented in the vertical direction.
[0012] The sound emission control devices 10L and 10R have the same configuration. Therefore, unless it is necessary to distinguish between them below, both will be collectively referred to as the sound emission control device 10. Similarly, speakers 110L and 110R will be collectively referred to as speaker 110 unless it is necessary to distinguish between them. Furthermore, sound emission holes 2FL and 2FR will be collectively referred to as sound emission hole 2F unless it is necessary to distinguish between them, and sound emission holes 2BL and 2BR will be collectively referred to as sound emission hole 2B unless it is necessary to distinguish between them.
[0013] Figure 2 is an assembly drawing showing a sound emission control device 10 installed on the speaker 110. The sound emission control device 10 has a tray section 20 installed on top of the speaker 110 and a lid section 30 installed on top of the tray section 20.
[0014] The speaker 110 has a hemispherical diaphragm 111 that vibrates in the Z-axis direction, and a cylindrical magnetic circuit section 112 that has a magnetic gap (not shown in Figure 2) that accommodates the annular peripheral portion of the diaphragm 111.
[0015] The tray section 20 has a horizontal plate section 21 and side wall sections 22FL, 22FR, 22BL, and 22BR. Here, the horizontal plate section 21 has a planar shape formed by joining the upper bases of two isosceles trapezoidal plate materials, each having an upper base and a lower base longer than the upper base. The side wall sections 22FL and 22FR rise from the left and right slanted sides of the isosceles trapezoidal region 21F on the front half of the horizontal plate section 21, and the side wall sections 22BL and 22BR rise from the left and right slanted sides of the isosceles trapezoidal region 21B on the rear half of the horizontal plate section 21. The side wall sections 22FL, 22FR, 22BL, and 22BR are each roughly triangular in shape, and their height increases as they move from the center of the horizontal plate section 21 toward the front or back of the electronic piano 100's casing.
[0016] In the central region of the horizontal plate section 21, that is, the region where the upper bases of the two isosceles trapezoids described above are joined, a through-hole 23 is provided to receive the hemispherical diaphragm 111 exposed from the magnetic circuit section 112. The tray section 20 is placed on the upper surface of the magnetic circuit section 112 while maintaining a horizontal position, with the diaphragm 111 inserted through this through-hole 23.
[0017] The cover part 30 includes a bottom wall part 31 composed of an isosceles trapezoidal area 31F on the front side and an isosceles trapezoidal area 31B on the back side similar to the horizontal plate part 21, a side wall part 32L rising from two hypotenuse sides on the left side of the bottom wall part 31, and a side wall part 32R rising from two hypotenuse sides on the right side of the bottom wall part 31. Here, the hypotenuse parts on the left and right sides of the lower surface of the bottom wall part 31 have a longer distance from the horizontal plate part 21 of the tray part 20 as they go from the center to the front side and the back side, and they are placed on the upper end surfaces of the side wall parts 22FL, 22FR, 22BL, and 22BR of the tray part 20 without gaps.
[0018] On the lower surface of the bottom wall part 31, the boundary between the isosceles trapezoidal area 31F and the isosceles trapezoidal area 31B is an edge-shaped branching part 33 that retreats semi-circularly upward. This semi-circular branching part 33 has its edge top in a plane including both the X-axis and the Z-axis passing through the center of the diaphragm 111 over its entire length, and faces the vibration surface of the hemispherical diaphragm 111 at substantially equal intervals.
[0019] When the bottom wall part 31 is cut by a plane including both the X-axis and the Z-axis passing through the position while changing the position on the Y-axis, the cross-sectional shape of the lower end part of the bottom wall part 31 is semi-circular at the position of the branching part 33 on the Y-axis, but gradually changes to a linear shape as it goes from the center of the electronic piano 100 toward the front side and the back side along the Y-axis. And at the front and back positions of the electronic piano 100, the cross-sectional shape of the lower end part of the bottom wall part 31 is linear.
[0020] FIG. 3 is a perspective view showing the configuration of the sound emission control device 10. FIG. 4 is a cross-sectional view taken along the line Ia-Ia' of FIG. 3, that is, a cross-sectional view of the sound emission control device 10 cut by a plane including the Z-axis passing vertically through the center of the diaphragm 111 and the X-axis passing through the center of the diaphragm 111 in the left-right direction of the electronic piano 100. Further, FIG. 5 is a cross-sectional view taken along the line Ib-Ib' of FIG. 3, that is, a cross-sectional view of the sound emission control device 10 cut by a plane including the Z-axis passing vertically through the center of the diaphragm 111 and the Y-axis passing through the center of the diaphragm 111 in the front-back direction of the electronic piano 100.
[0021] In Figure 3, the isosceles trapezoidal region 21F on the front side of the horizontal plate portion 21 in the tray portion 20, the side wall portions 22FL and 22FR, and the isosceles trapezoidal region 31F on the front side of the bottom wall portion 31 in the lid portion 30 constitute a guide 40F that guides the sound emitted from the vibrating surface of the diaphragm 111 and branched by the branching portion 33 to the sound emission hole 2F on the front side of the electronic piano 100.
[0022] Furthermore, the isosceles trapezoidal region 21B on the rear side of the horizontal plate portion 21 in the tray portion 20, the side wall portions 22BL and 22BR, and the isosceles trapezoidal region 31B on the rear side of the bottom wall portion 31 in the lid portion 30 constitute a guide 40B that guides the sound emitted from the vibrating surface of the diaphragm 111 and branched by the branching portion 33 to the sound emission hole 2B on the rear side of the electronic piano 100.
[0023] Guides 40F and 40B are two guides that guide the sound emitted from the diaphragm 111 and branched by the branching section 33 to the two outlets, which are sound emission holes 2FL (2FR) and 2BL (2BR) provided in the electronic piano 100 and facing in different directions, and each guide has a horn-shaped inner wall surrounding the space from each inlet to outlet. Guides 40F and 40B have the same shape and size. Therefore, in this embodiment, the sound branched by the branching section 33 enters guides 40F and 40B with the same sound pressure and is guided with the same sound pressure.
[0024] Guides 40F and 40B are horn-shaped guides whose opening cross-sectional area continuously widens from the diaphragm 111 side toward the sound outlets 2F and 2B side. The shape of the inner wall surface of guides 40F and 40B changes continuously from its entrance to its exit. More details are as follows.
[0025] In this embodiment, the guide 40F has two substantially triangular sides (side wall portions 22FL and 22FR) with two sides that move away from each other as you move from the entrance to the exit, and two substantially trapezoidal bottom surfaces (isosceles trapezoidal region 21F of the horizontal plate portion 21 and isosceles trapezoidal region 31F of the bottom wall portion 31) that widen as you move from the entrance to the exit. The opening cross-sectional area of this guide 40F increases as you move from the diaphragm 111 side to the sound emission hole 2F side. The guide 40B is similar, having substantially triangular sides and substantially trapezoidal bottom surfaces, and the opening cross-sectional area increases as you move from the diaphragm 111 side to the sound emission hole 2B side.
[0026] As shown in Figures 4 and 5, a voice coil 113 is wound around the periphery of the diaphragm 111, and this voice coil 113 is housed in the magnetic gap 114 of the magnetic circuit section 112. The diaphragm 111 vibrates in the direction of the drive axis Z, which passes vertically through the center of the diaphragm 111, when current is supplied to the voice coil 113. As a result, the vibrating surface of the diaphragm 111 emits sound. Note that in Figure 4, the side wall sections 29L and 29R are members of the tray section 20 that support the side wall sections 32L and 32R, and are omitted from the illustration in figures other than Figure 4.
[0027] In the bottom wall portion 31, the plane that includes the drive shaft Z and is perpendicular to the longitudinal axis Y forms the boundary between the isosceles trapezoidal region 31F of the guide 40F and the isosceles trapezoidal region 31B of the guide 40B. The branching portion 33 is located within the plane that includes the drive shaft Z and is perpendicular to the longitudinal axis Y. The length of this branching portion 33 is approximately the same as the diameter of the diaphragm 111.
[0028] Thus, in this embodiment, the multiple guides, guides 40F and 40B, each have an inlet connected to a branching section 33 facing the vibrating surface of the diaphragm 111. The guides 40F and 40B then guide the sound emitted from the vibrating surface of the diaphragm 111 and branched by the branching section 33 in different directions. More specifically, the guides 40F and 40B are perpendicular to the drive axis Z of the vibrating surface of the diaphragm 111 and guide the sound in multiple different directions, specifically in the directions of the sound emission holes 2F and 2B, which are opposite directions to each other.
[0029] Furthermore, focusing on the cross-sectional shapes of guides 40F and 40B cut by a plane that includes the drive shaft Z and the longitudinal axis Y (Figure 5), in the isosceles trapezoidal regions 31F and 31B of the bottom wall 31, the inner wall regions of guides 40F and 40B connected to the branching portion 33, specifically the isosceles trapezoidal regions 31F and 31B of the bottom wall 31, form an obtuse angle θ with respect to the drive shaft Z extending downward from the branching portion 33.
[0030] The inner wall shapes of guides 40F and 40B are as follows. Since the inner wall shapes of guides 40F and 40B are the same, only the inner wall shape of guide 40F will be described below.
[0031] The lower inner wall surface of the guide 40F, that is, the upper surface of the horizontal plate portion 21, is horizontal throughout its entire length. Thus, the inner wall of the guide 40F has a flat portion in at least a part of it.
[0032] The inner wall surfaces on the sides of the guide 40F, i.e., the inner wall surfaces of the side wall portions 22FL and 22FR, are aligned vertically throughout their entire length. Furthermore, the inner wall surfaces of the side wall portions 22FL and 22FR move further apart from each other as they move from the diaphragm 111 side toward the sound emission hole 2F side, and the gradient of each with respect to the longitudinal axis Y increases.
[0033] The upper inner wall surface of the guide 40F, that is, the lower surface of the isosceles trapezoidal region 31F of the bottom wall 31, moves away from the lower inner wall surface of the guide 40F as you move from the diaphragm 111 side toward the sound outlet 2F side. Also, the lower surface of the isosceles trapezoidal region 31F of the bottom wall 31, when cut by a plane perpendicular to the front-rear axis Y, is semicircular at the position of the branching portion 33, but continuously changes from semicircular to linear as you move toward the sound outlet 2F side.
[0034] Figure 6 is a plan view showing an electronic piano 100 placed in front of a wall 200, and users U1 and U2 listening to the sound emitted from this electronic piano 100. The effects of this embodiment will be explained below with reference to Figure 6.
[0035] The electronic piano 100 is played, and sound is emitted from the vibrating surfaces of the diaphragms 111 of speakers 110L and 110R. If, for example, sound emission control devices 10L and 10R with guides 40F and 40B are not provided, and the sound emitted from the vibrating surfaces of the diaphragms 111 of speakers 110L and 110R is simply split into two directions, front and back, the split sound will spread and propagate over a wide area, so the sound will reach the ears of users U1 and U2 after passing through multiple paths with different reflection points. As a result, users U1 and U2 will hear sound with large peaks and dips in the frequency response.
[0036] However, the electronic piano 100 in this embodiment is provided with sound emission control devices 10L and 10R having guides 40F and 40B. Therefore, the sound emitted from the vibrating surface of speaker 110L is branched to the front and rear sides by the branching section 33 of sound emission control device 10L, and guided by the guides 40F and 40B of sound emission control device 10L to be emitted from sound emission holes 2FL and 2BL. Similarly, the sound emitted from the vibrating surface of speaker 110R is branched to the front and rear sides by the branching section 33 of sound emission control device 10R, and guided by the guides 40F and 40B of sound emission control device 10R to be emitted from sound emission holes 2FR and 2BR.
[0037] Here, in each of the guides 40F and 40B, the space from the inlet (branching section 33) to the outlet (sound discharge holes 2F and 2B) is surrounded by an inner wall surface with a horn shape that changes continuously from the inlet to the outlet. As a result, the sound guided to the respective outlets of guides 40F and 40B has a directivity that does not change with frequency in both horizontal and vertical directions, and guides 40F and 40B function as constant directivity horns that provide a uniform radiation pattern. Therefore, the sound heard by user U1 is a high-quality sound without large peaks or dips in the frequency response.
[0038] Furthermore, in this embodiment, the two guides 40F that direct sound to the left and right sound holes 2FL and 2FR of the electronic piano 100 are identical in shape and function as constant-directivity horns with the same characteristics, so the user hears the sound emitted from the sound holes 2FL and 2FR. Therefore, even when the user U1 moves their head from side to side, the user U1 can hear sound with uniform frequency characteristics over a wide area.
[0039] Furthermore, each of the sound emission control devices 10L and 10R in this embodiment is equipped with guides 40F and 40B that guide in two opposite directions. Therefore, as illustrated in Figure 6, each sound emitted from speakers 110L and 110R is guided to the sound emission holes 2FL and 2FR by the guide 40F of the sound emission control devices 10L and 10R, while the sound emission holes 2BL and 2BR on the rear side of the electronic piano 100 are guided to the sound emission holes 2BL and 2BR by the guide 40B of the sound emission control devices 10L and 10R, and reflected off the wall surface 200. Consequently, user U1 and user U2 behind them hear a sound that is the sum of the sound from the sound emission holes 2FL and 2FR and the reflected sound from the wall surface 200.
[0040] Here, the sound heard by user U1 is stronger from the sound outlets 2FL and 2FR than from the reflected sound from wall 200. Similarly, the sound heard by user U2 is also stronger from the sound outlets 2FL and 2FR than from the reflected sound from wall 200, but user U2 is more sensitive to the reflected sound from wall 200 than user U1. However, the sound reflection by wall 200 has a sound diffusion effect.
[0041] Therefore, the sound heard by user U1, the performer, is a sound with a sense of spaciousness, similar to that emitted from an acoustic piano. On the other hand, user U2, positioned at a distance behind user U1, receives high-frequency sounds that would be attenuated in a normal structure without the sound emission control device 10, thanks to the function of the sound emission control device 10, as well as reflected sounds that have been diffused by reflection off the wall. Therefore, the sound heard by user U2 is similar to that of a piano, and has a wider sound image. Thus, according to this embodiment, the sound quality of the sound heard by the performer of the electronic piano 100 and the sound heard by listeners positioned at a distance from the performer can be improved.
[0042] <Other Embodiments> The embodiments of this invention have been described above, but other embodiments of this invention are also conceivable. For example, the following:
[0043] (1) In the above embodiment, the sound emitted from the vibrating surface was split into two, but a branching section that splits the sound into three or more branches, and three or more guides that guide the sound to three or more outlets which are connected to the respective inlets of this branching section and face different directions from one another may be provided.
[0044] (2) In the above embodiment, two sound emission control devices 10 are provided on the electronic piano 100, but sound emission control devices 10 may also be provided on sound devices other than the electronic piano 100, such as speakers. Furthermore, the number of sound emission control devices 10 provided on the sound device is arbitrary.
[0045] (3) In the above embodiment, the bottom walls of guides 40F and 40B were made into isosceles trapezoidal shapes, but they may also be trapezoidal shapes with two hypotenuses of different lengths.
[0046] (4) In the above embodiment, guides 40F and 40B guided the sound in the front-to-back direction of the electronic piano 100, but they may also guide the sound in a direction inclined with respect to the front-to-back direction.
[0047] (5) Figure 7 is a perspective view showing the configuration of another electronic piano 100a equipped with the sound emission control device of the above embodiment. In the electronic piano 100 of the above embodiment (Figure 1), left and right speakers 110L and 110R with sound emission direction facing upward and left and right sound emission control devices 10L and 10R are arranged near the top surface inside the housing. In contrast, in the electronic piano 100a shown in Figure 7, left and right speakers 110L and 110R with sound emission direction facing upward and left and right sound emission control devices 10L and 10R are arranged below the keyboard section 202 inside the housing. Furthermore, in the electronic piano 100a, sound emission holes 2FL and 2FR of the sound emission control devices 10L and 10R are provided below the keyboard section 202 on the front surface 201F of the housing, and sound emission holes 2BL and 2BR of the sound emission control devices 10L and 10R are provided below the keyboard section 202 on the rear surface 201B of the housing. In this configuration as well, the same effects as in the above embodiment can be obtained.
[0048] (6) Figure 8 is a perspective view showing another form of the electronic piano. Figure 9 is a cross-sectional view taken along line I-I' in Figure 8. In the electronic piano 100b shown in Figures 8 and 9, as with the electronic piano 100a in Figure 7, left and right speakers 110L and 110R, with sound emission direction facing upward, are positioned below the keyboard section 202 inside the enclosure. More specifically, two spaces are provided below the keyboard section 202 inside the enclosure to accommodate the left and right speakers 110L and 110R. Figure 9 shows one of these two spaces, space 203L. The speaker 110L, with sound emission direction facing upward, is supported within this space 203L. On the front 201F and rear 201B of the enclosure, sound emission holes 205FL and 205BL are provided below and to the left of the keyboard section 202, allowing space 203L to communicate with the outside of the enclosure. Although not shown in the diagram, the right speaker 110R also has a space similar to space 203L. Furthermore, on the front 201F and rear 201B of the enclosure, sound vents 205FR and 205BR are provided at the lower right position of the keyboard section 202, allowing the space housing speaker 110R to communicate with the outside of the enclosure. In this example, the two speakers 110L and 110R are housed in two separate spaces, but they may also be housed in a single space.
[0049] In this 100b digital piano, the sound emitted upward from the left and right speakers 110L and 110R is split to the front 201F and rear 201B sides, and emitted from the front sound vents 205FL and 205FR, and the rear sound vents 205BL and 205BR, respectively. Here, if the listener is positioned in front of the 100b digital piano, the sound emitted from the front sound vents 205FL and 205FR reaches the listener directly, while the sound emitted from the rear sound vents 205BL and 205BR reaches the listener after being reflected by the wall. Therefore, the sound heard by the listener can be given a sense of spaciousness. [Explanation of Symbols]
[0050] 100, 100a, 100b... Electronic piano, 110, 110L, 110R... Speaker, 111... Diaphragm, 112... Magnetic circuit section, 113... Voice coil, 114... Magnetic gap, 2FL, 2FR, 2BL, 2BR, 2F, 2B, 205FL, 205FR, 205BL, 205BR... Sound emission holes, 10, 10L, 10R... Sound emission control device, 40F, 40B... Guide, 33...branch section, 20...tray section, 30...lid section, 21...horizontal plate section, 21F, 21B, 31F, 31B...isospherical trapezoidal area, 22FL, 22FR, 22BL, 22BR, 32L, 32R, 29L, 29R...side wall section, 23...through hole, 31...bottom wall section, U1, U2...user, 201F...front, 201B...rear, 202...keyboard section, 203L...space.
Claims
[Claim 1] The acoustic device has multiple inlets connected to branching sections facing the vibrating surface within the acoustic device, multiple outlets provided in the acoustic device and facing in different directions from each other, and a horn-shaped inner wall surrounding the space from each inlet to outlet, and has multiple guides that guide the sound emitted from the vibrating surface and branched by the branching sections to the multiple outlets. The aforementioned multiple guides are identical in shape to each other and consist of two guides that guide sound in opposite directions, in a sound emission control device.