Speaker

Abstract

The present invention stably suppresses sound leakage in a backward direction even when no sound absorbing material is used. A first speaker unit is located in an enclosure formed by using a prescribed material, and a second speaker unit is located above the first speaker unit. The first speaker unit radiates a first sound toward the front side of the enclosure. The second speaker unit radiates a second sound toward the front side. The enclosure is provided with: a first sound hole part that emits a third sound which is 180 degrees out of phase with the first sound and emitted toward the back surface side due to emission of the first sound; and a second sound hole part for emitting a fourth sound which is 180 degrees out of phase with the second sound and emitted toward the back surface side due to emission of the second sound. The first sound hole part is provided on at least one of the front surface, the lower surface, and the side surface. The second sound hole is provided on at least one of the front surface, the upper surface, and the side surface.

Description

Speaker

[0001] The present disclosure relates to a sound leakage suppression technique for speakers.

[0002] In suppressing sound leakage from a speaker, among the sound waves radiated in the direction opposite to the user, the suppression of high-frequency components tends to be worse than that of low-frequency components. To address this, conventional speaker sound leakage suppression techniques may use sound-absorbing materials or the like to ensure control of the sound leakage distance (see, for example, Patent Document 1).

[0003] International Publication No. 2021 / 192166

[0004] However, sound leakage suppression using a sound-absorbing material may lack stability in the shape of the sound-absorbing material. Therefore, in vehicles such as automobiles, trains, and airplanes, even when using a sound leakage suppression technique using a sound-absorbing material, the performance of sound leakage suppression may not be stable.

[0005] An object of the present disclosure is to provide a speaker that can stably suppress sound leakage in the rear direction even when not using a sound-absorbing material.

[0006] A speaker according to one aspect of the present disclosure includes at least one enclosure formed using a predetermined material, a first speaker unit disposed within the enclosure and radiating a first sound toward the front side of the enclosure, a second speaker unit disposed above the first speaker unit within the enclosure and radiating a second sound toward the front side, a first sound hole portion provided on at least one of the front, bottom, and side surfaces of the enclosure for radiating a third sound that is the inverse phase of the first sound and is radiated toward the rear side accompanying the radiation of the first sound, and a second sound hole portion provided on at least one of the front, top, and side surfaces for radiating a fourth sound that is the inverse phase of the second sound and is radiated toward the rear side accompanying the radiation of the second sound.

[0007] According to the speaker of the present disclosure, sound leakage in the rear direction can be stably suppressed even when not using a sound-absorbing material.

[0008] Figure 1A shows a speaker according to the first embodiment. Figure 1B is a rear view of the speaker according to the first embodiment. Figure 2 is a diagram illustrating the sound hole section. Figure 3 is a cross-sectional view taken along line E-E in Figure 1A. Figure 4 shows an example of a case where an acoustic resistance section is provided in the sound hole section. Figure 5A shows the positional relationship of the measurement microphone in a measurement test, viewed from above the speaker. Figure 5B shows the positional relationship of the measurement microphone in a measurement test, viewed from the left side of the speaker. Figure 6 shows an example of the measurement results in a measurement test. Figure 7 shows a speaker according to a first modification of the first embodiment. Figure 8 shows a speaker according to a second modification of the first embodiment. Figure 9 shows a speaker according to a third modification of the first embodiment. Figure 10A shows a speaker according to the second embodiment. Figure 10B is a rear view of the speaker according to the second embodiment. Figure 11 shows a speaker according to a first modification of the second embodiment. Figure 12 shows a speaker according to a second modification of the second embodiment. Figure 13 shows a speaker according to a third modification of the second embodiment. Figure 14 shows a speaker according to the third embodiment.

[0009] The embodiments of this disclosure will be described in detail below. Components having the same function will be numbered identically, and redundant explanations will be omitted.

[0010] <<First Embodiment>> Figure 1A shows a speaker according to the first embodiment. Figure 1B is a rear view of the speaker according to the first embodiment. Figure 2 is a diagram illustrating the sound hole section. Figure 3 is a cross-sectional view taken along line E-E in Figure 1A. In Figure 1A, the front surface 11 is shown as a front view, and the left side view, right side view, top view, and bottom view of the speaker 1 are also shown. In the left side view and right side view in Figure 1A, the first speaker unit 50 and the second speaker unit 60 are not shown. The x, y, and z axes (coordinate axes) shown in Figure 1A are applied to the front view of Figure 1A. The notation method in Figure 1A is the same for Figures 7, 8, 9, 10A, and 11-14. In Figure 2, the first speaker unit 50 and the second speaker unit 60 are shown with dotted lines to illustrate the first sound hole section 21 and the second sound hole section 31. Figure 2 is a diagram illustrating the positional relationship between the speaker and the sound hole, and its aspect ratio does not necessarily match that of Figure 1A. The speaker 1 according to the first embodiment of this disclosure comprises a first speaker unit 50 and a second speaker unit 60 arranged within an enclosure 10.

[0011] (Enclosure 10) The enclosure 10 is a housing that corresponds to a so-called speaker box for housing the first speaker unit 50 and the second speaker unit 60. In this example, the enclosure 10 is made of resin, but the material is not limited to resin. It may be made of other predetermined materials other than resin, as long as it can achieve a stable structure and not transmit emitted sound, or produce a predetermined attenuation, and can exhibit effects equivalent to or better than those of the disclosure (hereinafter, materials that can exhibit such effects, including resin, will also be referred to as "predetermined materials"). In this example, the enclosure 10 has an outer shape that is a substantially rectangular parallelepiped with rounded corners. The speaker 1 of the disclosure is not limited in shape, and for example, the corners of the enclosure 10 do not have to be rounded.

[0012] The enclosure 10 has a front surface 11, side surfaces 12 and 13, a bottom surface 14, a top surface 15, and a rear surface 16. As will be described later, the enclosure 10 has first sound holes 21 and 22 and second sound holes 31 and 32.

[0013] In this example, the enclosure 10 has a partition 17 that separates (divides) the area where the first speaker unit 50 is placed from the area where the second speaker unit 60 is placed. In Figure 1A, the partition 17, which would normally not be visible from this viewpoint, is shown with a dotted line. Note that while it is preferable to have the partition 17 in the enclosure 10 from the standpoint of separating sound, it is not essential.

[0014] (First speaker unit 50) The first speaker unit 50 is positioned such that its front side (-y direction side) faces an opening 111 provided below the front surface 11 of the enclosure 10. The first speaker unit 50 is positioned in the lower section (-z direction side) of the enclosure 10. In this example, the opening 111 has a circular shape with a diameter equal to the diameter d1 of the first speaker unit 50. The first speaker unit 50 emits sound (hereinafter, this sound is also referred to as "sound based on the acoustic signal") from an input acoustic signal. In this disclosure, the acoustic signal input to the first speaker unit 50 is referred to as the "first acoustic signal". The first speaker unit 50 is positioned inside the enclosure 10 and emits sound based on the first acoustic signal (hereinafter, also referred to as "first sound") toward the front surface 11 of the enclosure 10. The size of the opening 111 may be appropriately changed depending on the type and shape of the first speaker unit 50 used, the installation conditions, the shape of the enclosure, etc. The opening may be larger or smaller than the diameter d1, as long as the shape allows the first speaker unit 50 to be fixed to the front surface 11 and separates the output to the front side (-y direction) from the output to the rear side (+y direction).

[0015] (Second speaker unit 60) The second speaker unit 60 is positioned such that its front side (-y direction side) faces an opening 112 provided above the front surface 11 of the enclosure 10. The second speaker unit 60 is positioned above the first speaker unit 50 within the enclosure 10 and is positioned alongside the first speaker unit 50. In this example, the opening 112 has a circular shape with a diameter equal to the diameter d2 of the second speaker unit 60. The second speaker unit 60 emits the input acoustic signal as sound. In this disclosure, the acoustic signal input to the second speaker unit 60 is referred to as the "second acoustic signal". The second speaker unit 60 emits a sound based on the second acoustic signal (hereinafter also referred to as the "second sound") toward the front surface 11. The size of the opening 112 may be appropriately changed depending on the type, shape, installation conditions of the second speaker unit 60 used, the shape of the enclosure, etc. The opening may be larger or smaller than the diameter d2, as long as the shape allows the second speaker unit 60 to be fixed to the front surface 11 and separates the output to the front side (-y direction) from the output to the rear side (+y direction).

[0016] The first speaker unit 50 and the second speaker unit 60 each have circular portions with diameters d1 and d2, respectively. However, the speaker units of this disclosure are not necessarily limited to having circular portions, and may have other shapes such as rectangular portions, track-shaped portions, or elliptical portions. In this example, the center of the first speaker unit 50 and the center of the second speaker unit 60 are positioned at a distance Ld apart. The distances (lengths) of d1, d2, and Ld may be appropriately changed according to the desired sound suppression effect. For example, if d1 and d2 are 25 mm, Ld may be mounted at a distance of about 60 mm in order to achieve overall miniaturization of the speaker 1.

[0017] In this example, speaker 1 is configured assuming that the user's ear is positioned on the extension of the central axis of the circular shape of the first speaker unit 50. In this case, the first speaker unit 50 may be positioned as the main speaker unit and emit sound based on a positive-phase acoustic signal toward the front 11, while the second speaker unit 60 may be positioned as the cancel speaker unit and emit sound based on an out-of-phase acoustic signal toward the front 11. Note that the assumed ear position is not limited to the extension of the central axis of the circular shape of the first speaker unit 50, and may be appropriately changed depending on the equipment to which it is actually installed, for example, by shifting it slightly downward or to the side.

[0018] Speaker 1 may appropriately change the phase difference between the first speaker unit 50 and the second speaker unit 60. For example, it may be configured as follows: In the low-frequency region (hereinafter also referred to as the "first frequency region"), it may be controlled to be in phase with each other and emitted towards the front 11, and in the high-frequency region (hereinafter referred to as the "second frequency region"), it may be controlled to be out of phase with each other and emitted towards the front 11.

[0019] (First sound holes 21, 22) The enclosure 10 has first sound holes. In this example, the enclosure 10 has a first sound hole 21 on the left side surface 12 shown in Figure 1A, and a first sound hole 22 on the right side surface 13. In this example, the first sound holes 21 and 22 are positioned opposite to an axis (x-axis direction) that intersects horizontally with the central axis of the circular shape of the first speaker unit 50, starting from the center of gravity G1 of the first speaker unit 50 in the viewpoint of Figure 1A. The holes of the first sound holes 21 and 22 in this example have a rectangular shape. The length (length a1) of the holes of the first sound holes 21 and 22 is approximately the same as the diameter d1 of the first speaker unit 50. The length of the first sound holes 21 and 22 in the shorter direction (length b1) is formed to be shorter than the thickness of the first speaker unit 50 (see Figure 2). However, the size of the first sound holes 21 and 22 is not limited to the above and can be changed as appropriate to suit the desired sound leakage suppression effect. Also, although the first sound holes 21 and 22 in this example are rectangular, this shape is not limited to a rectangle and may be round or other shapes, taking into consideration the sound leakage suppression effect. In Figure 1A, the hole shapes of the first sound holes 21 and 22 are the same, but they may be different shapes or different sizes. The same applies to the second sound holes 31 and 32, which will be described later, in that the size and shape are not limited. The rectangular hole shape exemplified above may form a rectangle on its own, or it may be formed by providing many minute holes to make the whole appear rectangular. These points are also true when other hole shapes other than rectangles are used.

[0020] The first sound holes 21 and 22 and the first speaker unit 50 are arranged to maintain symmetry when viewed from the front 11 (see Figure 1A). The first sound holes 21 and 22 are arranged to be symmetrical with respect to the central axis C1 of the first speaker unit 50 when viewed from the sides 12 and 13 (see Figure 2). However, these are merely examples, and the arrangement of the first sound holes 21 and 22 is not limited to these. That is, the first sound holes 21 and 22 and the first speaker unit 50 may be asymmetrical when viewed from the front 11. The first sound holes 21 and 22 may be configured asymmetrical with respect to the central axis C1 of the first speaker unit 50 when viewed from the sides 12 and 13.

[0021] Generally, a speaker unit has a diaphragm inside that converts an electrical signal, which is an acoustic signal, into vibrations in the air. The speaker unit emits sound (sound waves) by vibrating the diaphragm inside the speaker unit. The diaphragm emits sound with opposite phases in the front and rear directions. Therefore, the first sound holes 21 and 22 emit sound (hereinafter also referred to as the "third sound") which is in the opposite phase to the first sound (first sound) emitted from the first speaker unit 50 toward the rear 16 side, opposite to the front 11 side, in conjunction with the emission of sound (first sound) based on the first acoustic signal toward the front 11 by the first speaker unit 50. Since the enclosure 10 is made of resin, it is configured to be difficult for sound to pass through. Therefore, the third sound emitted toward the rear 16 side wraps around inside the enclosure 10 and is emitted from the first sound holes 21 and 22.

[0022] (Second sound holes 31, 32) The enclosure 10 has second sound holes. In this example, the enclosure 10 has a second sound hole 31 on the left side surface 12 shown in Figure 1A, and a second sound hole 32 on the right side surface 13. In this example, the second sound holes 31 and 32 are positioned opposite to the axis (x-axis direction), which is the direction that intersects the circular central axis of the second speaker unit 60 horizontally, starting from the center of gravity G2 of the second speaker unit 60 in the viewpoint of Figure 1A. The holes of the second sound holes 31 and 32 in this example are rectangular in shape. The length (length a2) of the holes of the second sound holes 31 and 32 is approximately the same as the diameter d2 of the second speaker unit 60. The length of the second sound holes 31 and 32 in the shorter direction (length b2) is formed to be shorter than the thickness of the second speaker unit 60 (see Figure 2).

[0023] The second sound holes 31 and 32 and the second speaker unit 60 are arranged to maintain symmetry when viewed from the front 11. The second sound holes 31 and 32 are arranged to be symmetrical with respect to the central axis C2 of the second speaker unit 60 when viewed from the sides 12 and 13. However, these are merely examples, and the arrangement of the second sound holes 31 and 32 is not limited to these. That is, the second sound holes 31 and 32 and the second speaker unit 60 may be asymmetrical when viewed from the front 11. The second sound holes 31 and 32 may be configured asymmetrical with respect to the central axis C2 of the second speaker unit 60 when viewed from the sides 12 and 13.

[0024] The second sound holes 31 and 32 emit a sound (hereinafter also referred to as the "fourth sound") which is in the opposite phase to the second sound emitted from the second speaker unit 60 toward the rear 16, in conjunction with the emission of the sound (hereinafter also referred to as the "second sound") based on the second acoustic signal directed toward the front 11 by the second speaker unit 60. Therefore, similar to the first speaker unit 50, the fourth sound emitted toward the rear 16 wraps around inside the enclosure 10 and is emitted from the second sound holes 31 and 32.

[0025] Figure 4 shows an example of a case where an acoustic resistance section is provided in the sound hole section. The first sound hole section 21 and the second sound hole section 31 may be configured as acoustic resistance sections formed as mesh-like openings in each section, after dividing the opening as shown in Figure 4. Although the opening is divided in Figure 4, it may be made into a mesh-like shape without division depending on the size of the opening. The acoustic resistance section may be configured as a separate component and incorporated into the enclosure 10, or it may be configured integrally with the enclosure 10 as part of the enclosure 10. The acoustic resistance section may be provided in both the first sound hole section 21 and the second sound hole section 31, or in only one of the sound hole sections. The same applies to the first sound hole section 22 and the second sound hole section 32, in which acoustic resistance sections may be provided in all or some of the multiple sound hole sections. The same also applies to the first to third modifications of the first embodiment, the second embodiment, and the first to third modifications of the second embodiment, which will be described later.

[0026] <Confirmation of sound leakage suppression> Figure 5A shows the positional relationship of the measurement microphone in the measurement test, viewed from above the speaker. Figure 5B shows the positional relationship of the measurement microphone in the measurement test, viewed from the left side of the speaker. In Figure 5B, the microphone m10 and the first sound hole section 22 and the second sound hole section 32 are hidden, and the first speaker unit 50 and the second speaker unit 60, which should not be visible under normal circumstances, are shown with dotted lines.

[0027] The sound leakage suppression verification measurement in this disclosure was performed by measuring the test sound with the following specifications. The speaker enclosure 10 shown in Figures 1A and 1B was a roughly rectangular parallelepiped with a width W = 120 mm, a height H = 180 mm, and a depth D = 20 mm. d1 = d2 = 80 mm and Ld = 85 mm. The distance J (Figure 3) from the center of the speaker unit to the center of the sound hole was set to 54 mm. As shown in Figures 5A and 5B, the test sound measurement was performed by placing a microphone m0 at a position (L1 = 80 mm) 80 mm away from the front surface 11 of the speaker 1 on the front surface 11 side (-y direction side) of the central axis of the first speaker unit 50. The position of the microphone m0 is assumed to be the position of the user's ear. The microphone m0 is responsible for measuring the test sound heard by the user. In this measurement, each sound hole of speaker 1 (first sound holes 21, 22, second sound holes 31, 32) is configured to incorporate (attach) an acoustic resistance member, which is a separate mesh-like component, into its opening (see, for example, Figure 4).

[0028] As shown in Figures 5A and 5B, microphones m1 to m12 are arranged as follows: Microphone m1 is positioned on the circumference of a circle with a radius of 500 mm (L2 = 500 mm) with the vertical direction (z-axis direction) of speaker 1 as its central axis, and on the extension of length L1. Microphones m2 to m12 are positioned on the circumference of a circle with a radius of 500 mm (L2 = 500 mm) with the vertical direction (z-axis direction) of speaker 1 as its central axis, with one microphone positioned at each 30-degree clockwise rotation when viewed from above, starting from microphone m1. Microphones m1 to m12 are positioned to simulate the ear positions of people sitting around the user. Microphones m1 to m12 are responsible for measuring how much of the listening sound is leaking to people sitting around the user.

[0029] The primary purpose of this measurement was to confirm the performance difference between the conventional speaker and speaker 1; therefore, the same FIR filter, created on a workbench, was used for both.

[0030] Figure 6 shows an example of measurement results from a measurement test. Figure 6 shows the 1 / 3 octave analysis results, illustrating the difference in characteristics of the listening sound using a polar pattern. The solid line represents the results for the conventional speaker, and the dotted line represents the results for speaker 1. In Figure 6, a larger circle indicates greater leakage. In the figure, 0 degrees represents the front direction (front 11 side), and 180 degrees represents the rear direction (rear 16 side).

[0031] The specifications of the conventional speaker are as follows. The conventional speaker has a first speaker unit 50 and a second speaker unit 60 with the same specifications as speaker 1. The conventional speaker uses an aluminum baffle plate as its enclosure, which has holes that allow the front sides of the first speaker unit 50 and the second speaker unit 60 to be exposed. The first speaker unit 50 and the second speaker unit 60 are attached to this plate, and the back side is covered with White Cuon, a sound-absorbing material. The conventional speaker does not have sound holes. The external dimensions of the conventional speaker are the same as speaker 1: width W = 120 mm, height H = 180 mm, depth D = 20 mm, d1 = d2 = 80 mm, Ld = 85 mm.

[0032] As shown in Figure 6, in the low-to-mid frequency range below 1 kHz (100 Hz, 200 Hz, 400 Hz, 800 Hz, 1000 Hz in Figure 6), there was no significant difference in the characteristics of the sound being tested between the conventional speaker and speaker 1. On the other hand, in the mid-to-high frequency range (2000 Hz, 4000 Hz, 5000 Hz, 6300 Hz, 8000 Hz in Figure 6), speaker 1 showed less leakage in the 16 directions on the back (180 degrees in Figure 6) than the conventional speaker. Specifically, the difference in measured sound between the conventional speaker and speaker 1 at 180 degrees was 18 dB at 2000 Hz, 4 dB at 4000 Hz, 8 dB at 5000 Hz, 10 dB at 6300 Hz, and 13 dB at 8000 Hz.

[0033] Speaker 1 has an enclosure 10 made of resin. Speaker 1 employs a configuration in which the first speaker unit 50 and the second speaker unit 60 are covered with resin walls, which further suppresses sound emission to the rear (+y direction) starting from the enclosure 10. This suppresses leakage in the rear direction (+y direction), especially of high-frequency components with high directional properties. By covering the first speaker unit 50 and the second speaker unit 60 with resin walls, air mass is added, causing attenuation in the high-frequency range.

[0034] Although Helmholtz resonance occurs when the first speaker unit 50 and the second speaker unit 60 are covered with resin walls, the first sound holes 21, 22 and the second sound holes 31, 32 are configured to incorporate (attach) acoustic resistance members, which are separate mesh-shaped components, at their openings. This suppresses the occurrence of Helmholtz resonance and minimizes deterioration of sound leakage.

[0035] Based on the above, this measurement test confirmed that speaker 1 can control the distance of sound leakage in the rear direction even without using sound-absorbing material. In other words, it was confirmed that sound leakage in the rear direction can be suppressed. Suppressing sound leakage using sound-absorbing material can lack stability due to the shape of the sound-absorbing material, and in the case of using specific sound-absorbing materials, the effects of durability and wear due to aging deterioration may also be a factor. Speaker 1 is formed as a structure with a stable shape because the enclosure 10 is made of a predetermined material, and this allows for stable suppression of sound leakage in the rear direction. Furthermore, since speaker 1 does not require the use of sound-absorbing material as in conventional designs, space for mounting sufficient sound-absorbing material is not necessarily required, thus enabling space saving.

[0036] <Effect of distance between speaker unit and sound hole> From the first sound holes 21 and 22, the third sound, which is in the opposite phase to the first sound, is emitted through the enclosure 10. From the second sound holes 31 and 32, the fourth sound, which is in the opposite phase to the second sound, is emitted through the enclosure 10. Therefore, the closer (shorter) the distance between each speaker unit and the sound hole, the more effectively sound leakage can be suppressed up to the high-frequency range. However, in this case, sound leakage in the low-frequency range will also be suppressed. Therefore, the distance between the first sound holes 21 and 22 and the first speaker unit 50, or the distance between the second sound holes 31 and 32 and the second speaker unit 60, should be adjusted appropriately according to the frequency range in which sound leakage should be suppressed. For example, to minimize sound leakage in the desired low-frequency range, the first sound holes 21 and 22 and the first speaker unit 50 are separated by a predetermined distance or more, or the second sound holes 31 and 32 and the second speaker unit 60 are separated by a predetermined distance or more.

[0037] On the other hand, if the distance between the speaker unit and the sound port is too great, a phase shift in the sound occurs, making it impossible to maintain the inverse phase relationship, and as a result, the sound leakage suppression effect is lost. Therefore, we used simulations to confirm how far away the sound port can be from the speaker unit.

[0038] In this simulation, a simulation model was created in which a single speaker unit was placed inside an enclosure with sound holes on both sides. The same listening test measurements as described above were reproduced using numerical simulation, and the power results based on the positional relationship between the speaker unit and the sound holes were analyzed. According to the simulation results in this model, for example, in order to suppress sound leakage up to 3 kHz, the distance from the center of the speaker unit to the center of the sound hole (corresponding to distance J in Figure 3) needs to be 90 mm or less.

[0039] <<Modifications of the First Embodiment>> Figure 7 shows a speaker according to the first modification of the first embodiment. Figure 8 shows a speaker according to the second modification of the first embodiment. Figure 9 shows a speaker according to the third modification of the first embodiment.

[0040] In the speaker 1 of FIG. 1A, the first sound hole portion and the second sound hole portion were provided on each of the side surfaces 12 and 13, but in the enclosure 10, as shown in FIG. 7, the sound hole portion may be provided only on one side surface. As shown in FIG. 8, in addition to providing the sound hole portion at the position shown in FIG. 1A, the first sound hole portion 23 may be provided on the lower surface 14 and the second sound hole portion 33 may be provided on the upper surface 15. As shown in FIG. 9, in addition to providing the sound hole portion at the position shown in FIG. 7, the first sound hole portion 23 may be provided on the lower surface 14 and the second sound hole portion 33 may be provided on the upper surface 15.

[0041] For example, when the speaker 1 is arranged in a vehicle, it is assumed that one of the sound hole portions has to be closed. Therefore, in order to cope with various situations, freedom is given to the positions where the first sound hole portions 21, 22 and the second sound hole portions 31, 32 are provided, and the sound hole portion is arranged at an appropriate position of the enclosure in view of the effect of suppressing sound leakage, so that it can be configured to be audible only in the vicinity of the speaker 1.

[0042] Even in the case where no sound-absorbing material is used in the speaker 1 according to this modification, sound leakage in the back direction can be stably suppressed. Also, similar to the first embodiment, space saving can be achieved.

[0043] <<Second Embodiment>> FIG. 10A is a view showing a speaker according to the second embodiment. FIG. 10B is a rear view of the speaker according to the second embodiment. As shown in FIG. 10A, the enclosure 10B has first sound hole portions 21f, 22f. The first sound hole portions 21f, 22f are provided on the front surface 11 of the enclosure 10B. The first sound hole portions 21f, 22f emit a third sound that is the inverse phase of the first sound emitted from the first speaker unit 50 toward the back surface 16 side opposite to the front surface 11 side along with the emission of the first sound.

[0044] The enclosure 10B has second sound hole portions 31f, 32f. The second sound hole portions 31f, 32f are provided on the front surface 11 of the enclosure 10B. The second sound hole portions 31f, 32f emit a fourth sound that is the inverse phase of the second sound emitted from the second speaker unit 60 toward the back surface 16 side along with the emission of the second sound.

[0045] Even if the sides of the speaker are covered, for example, by a headrest, the sound port is positioned on the front side facing the user, as shown in speaker 1B in Figure 10A, making it possible to hear only in the vicinity of speaker 1B.

[0046] The distance between the first sound holes 21f, 22f and the first speaker unit 50, or the distance between the second sound holes 31f, 32f and the second speaker unit 60, is adjusted as appropriate to the frequency range in which sound leakage is to be suppressed. If the distance between each speaker unit and the sound holes is too close to a predetermined distance, the audible range will be too close to the first speaker unit 50 and the second speaker unit 60. Therefore, for example, to avoid suppressing sound leakage in the desired low-frequency range as much as possible, the distance between the first sound holes 21f, 22f and the first speaker unit 50 is set to a predetermined distance or more, or the distance between the second sound holes 31f, 32f and the second speaker unit 60 is set to a predetermined distance or more.

[0047] In the second embodiment as well, sound leakage toward the rear can be suppressed even when no sound-absorbing material is used. Since the enclosure 10B is formed from a predetermined resin material, it is formed as a structure with a stable shape, thereby reliably suppressing sound leakage toward the rear. Furthermore, since it is not essential for the speaker 1B to use sound-absorbing material as in the conventional method, space for mounting sufficient sound-absorbing material is not necessarily required, thus enabling space saving.

[0048] <<Modification of the Second Embodiment>>FIG. 11 is a diagram showing a speaker according to a first modification of the second embodiment. FIG. 12 is a diagram showing a speaker according to a second modification of the second embodiment. FIG. 13 is a diagram showing a speaker according to a third modification of the second embodiment. In the speaker 1B shown in FIG. 10A, the first sound hole portions 21f and 22f and the second sound hole portions 31f and 32f are provided on the side surface 12 side and the side surface 13 side of the front surface 11, respectively. However, in the enclosure 10B, as shown in FIG. 11, the sound hole portion may be provided only on one side surface side of the front surface 11. As shown in FIG. 12, in addition to providing the sound hole portion at the position of FIG. 10A, the first sound hole portion 23f may be provided on the lower surface 14 side of the front surface 11, and the second sound hole portion 33f may be provided on the upper surface 15 side of the front surface 11. As shown in FIG. 13, in addition to providing the sound hole portion at the position shown in FIG. 11, the first sound hole portion 23f may be provided on the lower surface 14 side of the front surface 11, and the second sound hole portion 33f may be provided on the upper surface 15 side of the front surface 11. Even in this modification, even when the sound absorption material is not used, the sound leakage in the back direction can be stably suppressed. Also, similar to the second embodiment, space saving can be achieved.

[0049] <<Third Embodiment>>The enclosures 10 and 10B of the present disclosure are not limited to a rectangular parallelepiped, and may have other shapes such as a cube, a cylindrical shape, or a combination of shapes such as a cylindrical shape on the upper side and a rectangular parallelepiped on the lower side.

[0050] Figure 14 shows a speaker according to the third embodiment. For example, in the speaker 1C having an enclosure 10C whose front surface is similar to a rounded rectangle or ellipse as shown in Figure 14, sound holes may be provided on the surface (side surface) that forms the circumference including an arc region. In this example, first sound holes 21a, 21b, and 21c are provided as corresponding to the first sound hole 21 of speaker 1, and second sound holes 31a, 31b, and 31c are provided as corresponding to the second sound hole 31 of speaker 1. In the third embodiment as well, sound leakage in the rear direction can be suppressed even without using sound-absorbing material. Since the enclosure 10C is formed from a predetermined material, it is formed as a structure with a stable shape, thereby stably suppressing sound leakage in the rear direction. Furthermore, since it is not essential to use sound-absorbing material in speaker 1C as in the conventional, space for mounting sufficient sound-absorbing material is not necessarily required, thus enabling space saving. Furthermore, the first sound holes 21a, 21b, 21c and the second sound holes 31a, 31b, 31c may each be provided with an acoustic resistance section (see Figure 4).

[0051] The first to third embodiments of the speaker of this disclosure, and modifications of the first and second embodiments (hereinafter collectively referred to as the "first to third embodiments") have been described above.

[0052] In the first to third embodiments, the sound holes were provided on at least the side or front of the enclosure 10, 10B, and 10C, but the location of the sound holes in the speaker of this disclosure is not limited to these. The sound holes in the speaker of this disclosure do not have to be provided on the side 12, 13 or front 11 of the enclosure 10, but may be configured to be provided on either the bottom surface 14 or the top surface 15 depending on the user's usage.

[0053] In the first to third embodiments, the first speaker unit 50 and the second speaker unit 60 were arranged side by side in the vertical direction (z-axis direction), but the speaker of this disclosure is not limited to this arrangement. For example, they may be arranged side by side in the horizontal direction (x-axis direction), and the shape of the enclosure 10 may be changed as appropriate to match this. Also, the number of speaker units arranged in the enclosure 10 is not limited to the two shown in this embodiment, but may be one or three or more.

[0054] The speaker of this disclosure may, for example, have a damping member mounted in at least one of the air gaps between the rear of the enclosure 10 and the first speaker unit 50 (first air gap K1), or between the rear of the enclosure 10 and the second speaker unit (second air gap K2) (see Figure 2), which dampens at least one of the third or fourth sound.

[0055] In the speaker 1 of this disclosure, the first speaker unit 50 and the second speaker unit 60 are both arranged along the front surface 11. However, they do not necessarily have to be arranged in alignment with a predetermined plane, for example, the second speaker unit 60 may be slightly shifted in the +y-axis direction relative to the first speaker unit 50.

[0056] In the speaker 1 of this disclosure, the first speaker unit 50 and the second speaker unit 60 are arranged facing the front surface 11 (facing in the -y direction), but they may also be arranged at a predetermined angle to the front surface 11, for example, slightly facing in the z direction.

[0057] In the speaker 1 of this disclosure, the positions of the first speaker unit 50 and the second speaker unit 60 may be swapped.

[0058] In this disclosure, the case with two speaker units was used as an example, but as long as the configuration relationship between the speaker unit and the sound hole is as described above, there may be one speaker unit or three or more.

[0059] In this disclosure, the hole shapes of the first sound holes 21, 22 and the second sound holes 31, 32 are described using the same shape as an example. However, for example, if you want to change the sound leakage suppression effect on the left side and the sound leakage suppression effect on the right side from the viewpoint of Figure 1A, you can make the size of the sound holes on one side larger or smaller than the size of the sound holes on the other side, thereby creating a difference in the size of the sound holes on the left and right sides. Specifically, the size of the first sound hole 21 may be larger or smaller than the first sound hole 22.

[0060] When the size of the sound holes differs between the left and right sides, that is, when there is a difference in the size of the sound holes on the left and right, the acoustic characteristics of the state before the difference was introduced can be maintained by keeping the sum of the sizes of the left and right holes the same as the sum of the sizes of the holes after the difference was introduced. If the sum of the sizes of the left and right sound holes becomes smaller than before the difference was introduced, resonance and pressure inside the speaker unit will increase, and the lowest reproducible frequency will rise. Therefore, in order to maintain the acoustic characteristics of the state before the difference was introduced, the sum of the sizes of the left and right sound holes must be the same before and after the difference was introduced.

[0061] The shape of the speaker disclosed herein is not limited, as long as sound holes are provided. For example, in the first embodiment, the first sound holes 21 and 22 are described as rectangular in shape, but this is merely an example, and they can be changed to a round shape or other shapes. Furthermore, the size of the sound holes is not limited. For example, in the first embodiment, the length in the longitudinal direction of the hole shape of the first sound holes 21 and 22 (length a1) is described as being approximately the same as d1, but this is also an example, and it can be changed to be longer or shorter than d1.

[0062] The first to third embodiments were described using examples in which multiple speaker units are arranged in a single enclosure, but the speaker of this disclosure is not limited to a single enclosure. For example, multiple enclosures, each with one speaker unit, may be arranged. Multiple enclosures, each with multiple speaker units, may be arranged. When three or more speaker units are arranged in a single enclosure, or when multiple enclosures, each with one speaker unit, are arranged, the phases between adjacent speaker units may be configured to be approximately out of phase with respect to each other. For example, in Figure 1A, when yet another speaker unit (hereinafter also referred to as "third speaker unit 70") is arranged above the second speaker unit 60, it will be as follows. In other words, the phases of the first speaker unit 50 and the third speaker unit 70 should be approximately the same, and the phase of the second speaker unit 60 should be controlled to be approximately out of phase with either the first speaker unit 50 or the third speaker unit 70. Furthermore, when three or more speaker units are arranged in one enclosure, or when multiple enclosures are arranged, each containing one speaker unit, the phases between some of the adjacent sets of speaker units may be configured to be approximately out of phase with each other. In other words, the phases between some of the sets of speaker units may be configured to be approximately out of phase with each other, while the phases between the remaining sets of speaker units may be configured to be approximately in phase with each other.

[0063] The speaker disclosed herein can be widely applied without limiting its use to automotive, railway, or furniture applications.

[0064] Furthermore, it goes without saying that the enclosure 10 (10B, 10C), the first speaker unit 50, the second speaker unit 60, or the first sound holes 21, 22, and the second sound holes 31, 32 described in this embodiment can be modified as appropriate without departing from the spirit of this disclosure.

[0065] The "specified material" mentioned above may be a metal such as aluminum, titanium, or stainless steel, as well as wood or an elastic material such as rubber. The resin mentioned above may be a plastic such as PLA, ABS, PET, or polycarbonate.

[0066] In the description of speaker 1, it was explained that the assumed ear position may be changed as appropriate depending on the equipment to which it is actually attached, for example, by shifting it slightly downward or to the side. Specific examples of this include: (1) the extension of the central axis may be positioned above the user's ear, for example, above the helix; (2) the extension of the central axis may be positioned laterally to the user's ear, for example, towards the face or back of the head from the ear canal; or a combination of the above (1) and (2) may be used.

[0067] The basic concept regarding the definition of a "face" in the enclosure described in this disclosure is as follows: In the above-described embodiment, the face on the side from which the first or second sound is emitted is the front face, and the face on the opposite side of the front face (the +y direction side in Figure 1A) is the back face. When the enclosure is placed on a predetermined surface such as a stand, the face corresponding to the bottom face is the bottom face, and the face on the opposite side of the bottom face (the +z direction side in Figure 1A) is the top face. When the enclosure is placed, the face surrounded by the front face, back face, top face, and bottom face, and located on the left side when viewed from the front side (the -x direction side in Figure 1A), is the left side face. When the enclosure is placed, the face surrounded by the front face, back face, top face, and bottom face, and located on the right side when viewed from the front side (the +x direction side in Figure 1A), is the right side face. This approach is equivalent to considering the normals of each face when the enclosure 10 shown in Figure 1A is a box-shaped structure based on a hexahedron, and defining each face based on the direction in which those normals point when the enclosure is placed on a predetermined surface.

[0068] As previously stated, the enclosure of this disclosure is not limited to a rectangular parallelepiped. For example, it is conceivable that the entire enclosure may be composed of an elliptical shape. That is, the enclosure of this disclosure is not necessarily composed of only six planes, but may have curved surfaces in part or in whole, or may be composed of more faces. To determine which of the above-mentioned faces of the enclosure (front, back, top, bottom, left side, right side) each face belongs to, one should consider the position of the face in question (the face being judged) within the entire enclosure, and use the direction of the normal of that face as a basic criterion: which direction is closest to the front side, back side, top side, bottom side, left side side, or right side side (in Figure 1A, the -y direction, +y direction, +z direction, -z direction, -x direction, +x direction).

[0069] For example, consider the enclosure 10 shown in Figure 1A, which has an external shape in which the upper corner of the left side is cut off, that is, a shape in which another plane (hereinafter also referred to as "plane X") is provided in the area enclosed by the top surface 15, side surface 12, front surface 11, and back surface 16, such that the boundary line of the plane can be clearly identified. In this case, by determining which of the planes the normal of plane X is closest to, it is determined that plane X belongs to the plane with the closest normal. In other words, in this example, it is sufficient to determine which of the top surface 15, side surface 12, front surface 11, and back surface 16 plane plane X belongs to (or which plane it is considered to be part of).

[0070] As for the shape of the enclosure in this disclosure, for example, it is conceivable that a part of the surface has a portion where, for example, curved surfaces are continuously connected, and the boundary line of the surface cannot be clearly determined. In this case, first, the portion with an unclear boundary line is identified, and the surface that includes the identified portion and is extended to a region with a clear boundary line is considered as one surface (hereinafter also referred to as "surface Y"). Next, this surface Y is divided into multiple regions (y1, y2, y3, ..., yn) such that the characteristics of each curved surface are included, and a determination is made based on which of the surfaces surrounding surface Y the normal of each region is closest to. For example, suppose that surface Y is a surface that corresponds to the same region as surface X described above. That is, suppose that surface Y is a surface enclosed by the front surface 11, the back surface 16, the top surface 15, and the side surface 12. As previously described, surface Y is a surface in which the boundary line of the surface cannot be clearly determined and which has multiple continuous curved surfaces. In this case, by dividing surface Y into multiple regions (y1, y2, y3, ..., yn) and checking the direction of the normals, it can be determined, for example, that y1 and y2 belong to the side surface 12, and y3 belongs to the top surface 15.

[0071] As an alternative enclosure shape, for example, the surface corresponding to the left side is composed of three surfaces (referred to here from top to bottom as "surface A1," "surface A2," and "surface A3"). Surfaces A1 and A2 are connected, and surfaces A2 and A3 are connected. From the viewpoint in Figure 1A, surfaces A1 and A3 have normals pointing to the left (-x direction) and have a relative step difference. Specifically, surface A1 is located to the left (-x direction) of surface A3 (shifted). Surface A2 is assumed to be a surface in a sufficiently small area compared to surfaces A1 and A3. That is, surface A2 is a small surface that connects the step difference between surfaces A1 and A3; in other words, surface A2 is a small surface that complements surfaces A1 and A3. In this case, the normal of surface A2 will point in a different direction from the normals of surfaces A1 and A3. However, surface A2 is considerably smaller than surfaces A1 and A3, and is located on the left side of the overall shape. Therefore, in this case, surface A2 is judged to be a surface belonging to the left side, just like surfaces A1 and A3. In other words, when determining whether a surface constituting the enclosure is the front, back, top, bottom, left side, or right side as described above, the direction of the normal of the surface being judged, as well as its position within the overall enclosure, should be taken into full consideration when making the determination.

[0072] 1, 1B, 1C Speaker 10, 10B, 10C Enclosure 11 Front 111, 112 Opening 12, 13 Side 14 Bottom 15 Top 16 Rear 17 Partition 21, 21a, 21b, 21c, 21f, 22f First sound hole 31, 31a, 31b, 31c, 31f, 32f Second sound hole 50 First speaker unit 60 Second speaker unit 70 Third speaker unit a1, a2, b1, b2, L1, L2, Ld Length C1, C2 Center axis d1, d2 Diameter D Depth G1, G2 Center of gravity H Height K1 First gap K2 Second gap m0-m12 Microphone W Width

Claims

1. A speaker comprising: at least one enclosure formed using a predetermined material; a first speaker unit disposed within the enclosure and emitting a first sound toward the front of the enclosure; a second speaker unit disposed above the first speaker unit within the enclosure and emitting a second sound toward the front; a first sound hole provided on at least one of the front, bottom, and side surfaces of the enclosure for emitting a third sound which is in the opposite phase to the first sound and is emitted toward the rear in conjunction with the emission of the first sound; and a second sound hole provided on at least one of the front, top, and side surfaces for emitting a fourth sound which is in the opposite phase to the second sound and is emitted toward the rear in conjunction with the emission of the second sound.

2. The speaker according to claim 1, wherein the predetermined material is a material that does not transmit emitted sound or causes a predetermined attenuation.

3. The speaker according to claim 1, wherein the center of the first sound hole is located at a position opposite to the axis, with the axis being in a direction that intersects horizontally with respect to the central axis of the front side of the first speaker unit.

4. The speaker according to claim 1, wherein at least one of the first sound hole portion or the second sound hole portion is provided with an acoustic resistance portion.

5. The speaker according to claim 1, wherein the enclosure has a partition that separates an area for arranging the first speaker unit from an area for arranging the second speaker unit.

6. The speaker according to claim 1, wherein the distance between the first sound hole and the first speaker unit is adjusted to match the frequency range for suppressing sound leakage.

7. The speaker according to claim 1, wherein the distance between the second sound hole and the second speaker unit is adjusted to match the frequency range for suppressing sound leakage.

8. The speaker according to any one of claims 1 to 7, wherein at least one of the first air gaps between the rear surface of the enclosure and the first speaker unit, or the second air gap between the rear surface of the enclosure and the second speaker unit, is provided in at least one of the air gaps, which reduces at least one of the third sound or the fourth sound.

Images