Sound emission control device

Abstract

To provide a sound emission control device that performs adjustment so that sound in a specific frequency band is heard at a desired sound pressure level.SOLUTION: A sound emission control device 200 has a tapered diffuser 230 whose tip faces a sound-emitting surface of a diaphragm 120 of a speaker unit 100, and a first waveguide 210 which surrounds a vibration axis Z of the diaphragm 120 and has an aperture 201 allowing sound emitted from the diaphragm 120 to pass through and propagate towards a diffuser 230. The distance of the aperture 201 from a vibration axis Z varies along the circumferential direction around the vibration axis Z.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sound emission control device that controls the directivity of a speaker. [Background technology]

[0002] Speakers such as dynamic speakers that vibrate a diaphragm have a strong directivity in the forward direction. For this reason, in electronic musical instruments and the like, a sound emission control device called a diffuser is placed in front of the speaker to diffuse the sound emitted from the speaker. For example, in the sound emission control device disclosed in Patent Document 1, a conical diffuser with its tip facing the diaphragm is placed in front of the speaker. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Utility model registration No. 3241907 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are speakers, such as mid-range speakers, that are required to produce a specific frequency band at a desired sound pressure. However, the conventional sound emission control devices described above have a problem in that it is difficult to adjust the sound so that the specific frequency band is produced at the desired sound pressure.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a sound emission control device that can adjust sounds in a specific frequency band so that they are heard at a desired sound pressure. [Means for solving the problem]

[0006] The present invention provides a sound emission control device comprising: a tapered diffuser whose tip faces the sound emission surface of a diaphragm; and a first wave guide which surrounds the vibration axis of the diaphragm and has a first opening which passes sound emitted from the diaphragm and propagates it towards the diffuser, wherein the distance of the first opening from the vibration axis varies along the circumferential direction around the vibration axis. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view of a sound emission control device and a speaker unit according to an embodiment of the present invention; [Figure 2] FIG. [Figure 3] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] 1 is a cross-sectional view showing the configuration of a sound emission control device 200 according to an embodiment of the present invention and a speaker unit 100 to which the sound emission control device 200 is attached. The sound emission control device 200 and the speaker unit 100 are installed inside the housing of a keyboard electronic musical instrument.

[0010] The speaker unit 100 is a device that emits sound by vibrating an axisymmetric, specifically cone-shaped, diaphragm 120 in the direction of a vibration axis Z. In this embodiment, the speaker unit 100 is a squawker for reproducing mid-range sounds. In this embodiment, the central axis (or axis of symmetry) of the diaphragm 120 is the vibration axis Z. In the following, the upper side in FIG. 1 may be referred to as the +Z side or +Z direction, and the lower side as the -Z side or -Z direction. The same applies to FIGS. 2 and 3, which will be described later.

[0011] The top of diaphragm 120 is fixed to circular frame 122 by edge 121, which is a circular elastic member. Diaphragm 120 has an opening 123 at its bottom, into which a cylindrical hollow cone top 124 is inserted and fixed. Cone top 124, exposed in the +Z direction from opening 123 of diaphragm 120, is covered by dust cap 125 fixed to diaphragm 120.

[0012] The sides of diaphragm 120 and cone top 124 are enclosed by frame 130. Frame 130 is a hollow, tray-shaped member that is fixed inside the housing of the keyboard electronic musical instrument. The aforementioned frame 122 is fixed to opening 131 at the top end of frame 130. The outer wall of cone top 124 is fixed to the inner wall of frame 130 by spider 126, which is an elastic member.

[0013] The frame 130 has an opening in the bottom 132, through which the lower end of the cone top 124 passes in the -Z direction. A voice coil (not shown) is wound around the outer periphery of the lower end of the cone top 124.

[0014] The speaker unit 100 has a magnetic circuit 110. This magnetic circuit 110 has a disk-shaped yoke 111 that is perpendicular to the vibration axis Z, a cylindrical pole piece 112 that protrudes in the +Z direction from the central region of this yoke 111, an annular magnet 113 that surrounds this pole piece 112 and is stacked in the peripheral region of the yoke 111, and an annular plate 114 that is stacked on this magnet 113. The space between the inner surface of plate 114 and the outer surface of the upper part of the pole piece 112 forms a magnetic gap G that generates a magnetic field.

[0015] The +Z side surface of plate 114 is fixed to bottom 132 of frame 130. The voice coil at the lower end of coil top 124 is inserted into magnetic gap G. In speaker unit 100, energization of this voice coil generates an electromagnetic force that drives diaphragm 120 in the direction of vibration axis Z, causing diaphragm 120 to emit sound.

[0016] The sound emission control device 200 has a first waveguide 210, a second waveguide 220, a diffuser 230, three connecting portions 240, a grill 250, and a frame 260 having a substantially circular ring shape.

[0017] Frame 260 is inserted into and fixed to a hole in horizontal plate 300 inside the housing of the keyboard electronic musical instrument. Grill 250 is a substantially cylindrical member with a top surface that has many holes that allow sound to pass through. Around grill 250, there is a cylindrical edge 251 that extends to the bottom end of frame 260, and edge 251 is fixed to frame 260.

[0018] Fig. 2 is a plan view of the sound emission control device 200 in Fig. 1 as seen from the +Z side. Fig. 3 is a cross-sectional view of the sound emission control device 200 cut along a plane including the vibration axis Z.

[0019] Here, first waveguide 210 is a substantially truncated cone-shaped member having opening 201 on the -Z side and circular opening 202 on the +Z side surrounding opening 201 in a plan view. Opening 201 is a first opening facing the sound emitting surface of diaphragm 120, and opening 202 is a circular opening located farther from the sound emitting surface than opening 201. The sound emitting surface of diaphragm 120 is a surface from which sound waves caused by vibration of diaphragm 120 are emitted, and in this embodiment, includes not only the +Z side surface of diaphragm 120 exposed from dust cap 125, but also the +Z side surface of dust cap 125. The +Z side surface of first waveguide 221 forms inclined surface 210a inclined with respect to vibration axis Z.

[0020] Opening 201 of first waveguide 210 is a first opening that surrounds vibration axis Z of diaphragm 120 and passes sound emitted from diaphragm 120 to propagate toward diffuser 230. In this embodiment, the distance of opening 201 from vibration axis Z varies along the circumferential direction around vibration axis Z.

[0021] More specifically, in this embodiment, the opening 201 is configured by a plurality of edges surrounding the vibration axis Z, and some of the plurality of edges are cutout portions 211a that increase in distance from the vibration axis Z. Hereinafter, the edges that are not cutout portions 211a among the plurality of edges will be referred to as edges 211b. In this embodiment, in the first opening 201, the cutout portions 211a and the edges 211b are alternately repeated along the circumferential direction centered on the vibration axis Z. Furthermore, the opening 201 of this embodiment is provided with six cutout portions 211a that are approximately arc-shaped, and these six cutout portions 211a form a petal shape as a whole.

[0022] The second waveguide 220 includes a substantially truncated cone-shaped member having a circular opening 203 on the -Z side and a circular opening 204 on the +Z side that surrounds the opening 203 in a plan view. Here, the opening 203 is a second opening that surrounds the first opening, opening 201. The second waveguide 220 also has a second opening and is a waveguide that surrounds the first waveguide 210. The opening 203 is located at a position as far away from the sound emitting surface as the opening 202, and the opening 204 is located farther from the sound emitting surface than the opening 203. Like the first waveguide 210, the second waveguide 220 has an inclined surface 220a that is inclined with respect to the vibration axis Z.

[0023] As shown in FIG. 2, the connecting portions 224 are plate-like members arranged radially at intervals of 120 degrees around the vibration axis Z, and connect the diffuser 230 to the area sandwiched between the two cutout portions 211a in the first waveguide 210 (i.e., the area facing the edge 211b), and further connect this area to the second waveguide 220.

[0024] Diffuser 230 is a tapered member with tip 231 facing the sound emitting surface of diaphragm 120. Specifically, diffuser 230 has a conical shape with pointed tip 231. An inclined surface 233 forming the outer surface of diffuser 230 is supported by first waveguide 210 and second waveguide 220 via connecting portion 240. First waveguide 210 and second waveguide 220 are inclined toward diffuser 230.

[0025] The upper end of edge portion 223 surrounds opening 204 of second waveguide 220, and extends in the -Z direction. Leg portions 225 protrude laterally from four locations on the lower end of edge portion 223. Screw holes 225a are formed in these legs 225. In this embodiment, by inserting screws 225b into these screw holes 225a, the sound emission control device 200 is fixed to a plate portion 300 inside the housing of the electronic keyboard instrument, as shown in FIG.

[0026] In this embodiment, a portion of the sound emitted from the sound emitting surface of diaphragm 120 passes through opening 201 of first waveguide 210 and is diffused horizontally by diffuser 230. A portion of the sound diffused by diffuser 230 is guided by inner inclined surface 210a of first waveguide 210 and propagates from grill 250 to the outside. The remaining portion of the sound diffused by diffuser 230 is guided by inner inclined surface 220a of second waveguide 220 and propagates from grill 250 to the outside.

[0027] In addition, the remaining part of the sound emitted from the sound emitting surface of the diaphragm 120, i.e., the sound that does not pass through the opening 201, passes through the back side of the first wave guide 210, is guided by the inner inclined surface 220a of the second wave guide 220, and is propagated from the grill 250 to the outside.

[0028] In this embodiment, opening 201 is provided with a plurality of cutouts 211a. These cutouts 211a are areas lacking material that blocks the passage of sound. Therefore, opening 201 with cutouts 211a allows sounds in a specific frequency band (specifically, midrange) to pass through more easily than openings without cutouts 211a. Therefore, this embodiment has the effect of increasing the sound pressure in the midrange of sounds heard by a listener sitting to the side of the keyboard electronic musical instrument.

[0029] As a result of trial and error by the inventors of the present application, it was confirmed that the sound pressure in a specific frequency band can be changed by changing the area and shape of the cutout portion 211a. Therefore, according to this embodiment, it is possible to adjust the sound so that a listener can hear a sound of a desired sound pressure in a specific frequency band.

[0030] Furthermore, according to this embodiment, part of the sound emitted from the sound emitting surface of diaphragm 120 is guided by first waveguide 210, and the remaining part is guided by second waveguide 220 and propagates to the outside through grill 250. Therefore, according to this embodiment, sound can be efficiently propagated to a listener sitting to the side of the keyboard electronic musical instrument.

[0031] <Other embodiments> Although one embodiment of the present invention has been described above, the present invention may have other embodiments, for example, as follows.

[0032] (1) In the above embodiment, the opening 201, which is the first opening, is petal-shaped and includes six cutouts 211a. However, the number of cutouts 211a is arbitrary. Furthermore, the overall shape of the first opening is not limited to a petal shape. Instead of providing cutouts in a perfectly circular first opening, the overall shape of the first opening may be a shape other than a perfect circle. The first opening may be, for example, star-shaped, triangular, elliptical, or the like.

[0033] (2) In the above embodiment, the plurality of cutout portions 211a have the same shape and area. However, the shape or area of ​​each cutout portion 211a may be different.

[0034] (3) The planar shape of the diaphragm 120 and the frame 260 surrounding it as viewed from the Z-axis direction does not need to be a perfect circle, and may be, for example, an ellipse. When the diaphragm 120 is elliptical, the sound pressure in the major axis direction is higher than the sound pressure in the minor axis direction. Therefore, it is preferable to orient the diaphragm 120 so that the minor axis direction of the diaphragm 120 coincides with the direction between the speaker unit 100 and the performer.

[0035] (4) A third waveguide may be provided outside the second waveguide to surround the second waveguide.

[0036] (5) As disclosed in Japanese Patent Application Laid-Open No. 2020-118360, a concentric mesh may be provided surrounding the second waveguide. [Explanation of symbols]

[0037] 100...speaker unit, 110...magnetic circuit, 111...yoke, 112...pole piece, 113...magnet, 114...plate, G...magnetic gap, 120...diaphragm, 125...dust cap, 124...cone top, 126...spider, 121...edge, 130...frame, 123...opening, 122...frame, 200...sound emission control device, 210...first wave guide, 220...second wave guide, 230...diffuser, 240...connecting portion, 260...frame, 250...grill, 300...plate portion, 211a...cutout portion, 211b...edge, 210a, 220a, 233...inclined surface, 231...tip portion, 225...leg portion, 225a...screw hole, 225b...screw.

Claims

1. a tapered diffuser whose tip faces the sound-emitting surface of the diaphragm; a first waveguide that surrounds the vibration axis of the diaphragm and has a first opening that passes sound radiated from the diaphragm and propagates it toward the diffuser; The sound emission control device wherein the distance of the first opening from the vibration axis varies along the circumferential direction around the vibration axis.

2. The sound emission control device according to claim 1 , wherein the first opening of the first waveguide is located between the diaphragm and the diffuser in the direction of the vibration axis.

3. The sound emission control device according to claim 1 , wherein the first opening has a notch that increases in distance from the vibration axis.

4. The sound emission control device according to claim 1 , further comprising a second opening surrounding the first opening and a second waveguide surrounding the first waveguide.

5. The sound emission control device according to claim 3 , further comprising a connecting portion that connects the area sandwiched between the two notches in the first waveguide to the diffuser.

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