Acoustic signal output device

Abstract

An acoustic signal output device includes: a speaker unit; a housing (collar) that accommodates a part of the speaker unit in order to cause an inverted sound played from the speaker unit in the direction of the rear surface of the speaker unit to be wound in the direction of the front surface of the speaker unit; the speaker unit is provided with an annular collar which is an annular member having a size capable of covering the periphery of the collar in the side direction, and the collar is provided with a first inverted sound playback hole for playing the inverted sound in the front direction of the speaker unit.

Description

Technical Field

[0001] The present invention relates to an acoustic signal output technology that can be used in an acoustic system provided in seats of an aircraft, an automobile, or the like. Background Art

[0002] Conventionally, in order to watch movies or listen to music in an aircraft, users have used earphones or headphones. This is because when using a speaker, the played sound reaches the surroundings of the user and causes trouble to other users. However, wearing earphones or headphones is troublesome for users. In addition, some users do not like wearing them for reasons such as messing up their hairstyles. There are also users who dislike the pressure on the ears caused by wearing them. Further, long-term wearing of earphones or headphones makes users feel auditory fatigue.

[0003] In order not to wear earphones or headphones, wavefront synthesis technology has been considered to synthesize a virtual sound field. However, in this case, it is necessary to prepare a large-scale speaker array, which is not practical. Therefore, in Patent Document 1, an acoustic signal output technology for a user using a seat in an aircraft that plays sound that cannot be heard by surrounding users without using earphones or headphones is disclosed.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent No. 6958763 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] However, in the technology of Patent Document 1, there is a problem that the sweet spot, which is the area where the played sound can be heard, is narrow. In addition, in the technology of Patent Document 1, there is a problem that two speaker units are required to play sound based on one acoustic signal.

[0009] Therefore, an object of the present invention is to provide an acoustic signal output technology that can increase the sweet spot in a limited area near the speaker unit.

[0010] Technical Solution for Solving the Technical Problem

[0011] One embodiment of the acoustic signal output device of the present invention includes: a speaker unit; a collar, which is a housing for a part of the speaker unit in order to direct the sound played from the speaker unit in the back direction of the speaker unit (hereinafter referred to as out-of-phase sound) to the front direction of the speaker unit; an annular collar, which is an annular member having a size capable of covering the periphery of the side direction of the collar; a hole (hereinafter referred to as the first out-of-phase sound playback hole) for playing the out-of-phase sound to the front direction of the speaker unit is provided in the collar, and the collar houses a part of the speaker unit in such a form that the path from the hole of the speaker unit for playing the out-of-phase sound to the first out-of-phase sound playback hole is shortened, and the resonance frequency of the internal space of the collar generated between the collar and the speaker unit becomes higher, so that in a specified frequency band in the front direction of the speaker unit, the out-of-phase sound played from the first out-of-phase sound playback hole and the sound played from the speaker unit in the front direction of the speaker unit (hereinafter referred to as in-phase sound) have a substantially out-of-phase relationship.

[0012] Advantages of the Invention

[0013] According to the present invention, it is possible to increase the sweet spot in a limited area near the speaker unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A diagram for explaining in-phase sound and out-of-phase sound.

[0015] Figure 2 A diagram showing an example of the configuration of the acoustic signal output device 100.

[0016] Figure 3 A diagram showing an example of the configuration of the acoustic signal output device 100.

[0017] Figure 4 A diagram showing a state where the acoustic signal output device 100 plays in-phase sound and out-of-phase sound.

[0018] Figure 5 A diagram for explaining Helmholtz resonance in the acoustic signal output device 100.

[0019] Figure 6 A diagram showing an example of the acoustic signal output device 100 having a baffle.

[0020] Figure 7 A diagram showing an example of the configuration of the acoustic signal output device 100.

[0021] Figure 8 A diagram showing an example of the configuration of the acoustic signal output device 100.

[0022] Figure 9 It is a diagram of Modification 1 of the first embodiment.

[0023] Figure 10 It is a diagram of Modification 2 of the first embodiment.

[0024] Figure 11 It is a diagram of Modification 3 of the first embodiment.

[0025] Figure 12 It is a diagram of Modification 4 of the first embodiment.

[0026] Figure 13 It is a diagram of Modification 5 of the first embodiment.

[0027] Figure 14 It is a diagram of Modification 6 of the first embodiment.

[0028] Figure 15 It is a diagram of Modification 7 of the first embodiment.

[0029] Figure 16 It is a diagram showing the acoustic signal output device used in the experiment.

[0030] Figure 17 It is a diagram showing the experimental results.

[0031] Figure 18 It is a diagram showing an example of the configuration of the acoustic signal output device 200.

[0032] Figure 19 It is a diagram showing an example of the configuration of the acoustic signal output device 200.

[0033] Figure 20 It is a diagram showing the situation where the acoustic signal output device 200 plays a positive-phase sound and an anti-phase sound.

[0034] Figure 21 It is a diagram showing an example of the acoustic signal output device 200 equipped with a baffle.

[0035] Figure 22 It is a diagram showing an example of the configuration of the acoustic signal output device 200.

[0036] Figure 23 It is a diagram showing an example of the configuration of the acoustic signal output device 200.

[0037] Figure 24 It is a diagram of Modification 1 of the second embodiment.

[0038] Figure 25 It is a diagram of Modification 2 of the second embodiment.

[0039] Figure 26 It is a diagram related to Modification 3 of the second embodiment.

[0040] Figure 27 It is a diagram related to Modification 4 of the second embodiment.

[0041] Figure 28 It is a diagram related to Modification 5 of the second embodiment.

[0042] Figure 29 It is a diagram related to Modification 6 of the second embodiment.

[0043] Figure 30 It is a diagram related to Modification 7 of the second embodiment.

[0044] Figure 31 It is a diagram showing the acoustic signal output device used in the experiment.

[0045] Figure 32 It is a diagram showing the experimental results.

[0046] Figure 33 It is a diagram showing an example of the configuration of the acoustic signal output device 300.

[0047] Figure 34 It is a diagram showing an example of the configuration of the acoustic signal output device 300.

[0048] Figure 35 It is a diagram showing the situation where the acoustic signal output device 300 plays the in-phase sound and the out-of-phase sound.

[0049] Figure 36 It is a diagram for explaining the Helmholtz resonance in the acoustic signal output device 300.

[0050] Figure 37 It is a diagram for explaining the longitudinal and transverse directions of the baffle.

[0051] Figure 38 It is a diagram related to Modification 1 of the third embodiment.

[0052] Figure 39 It is a diagram related to Modification 1 of the third embodiment.

[0053] Figure 40 It is a diagram related to Modification 2 of the third embodiment.

[0054] Figure 41 It is a diagram related to Modification 3 of the third embodiment.

[0055] Figure 42 It is a diagram showing an example of the configuration of the acoustic signal output device 400.

[0056] Figure 43 This is a diagram showing an example of the configuration of the acoustic signal output device 500.

[0057] Figure 44 This is a diagram showing an example of the configuration of the acoustic signal output device 500.

[0058] Figure 45 This is a diagram showing an example of the in-vehicle acoustic signal output device 500.

[0059] Figure 46 This is a diagram showing an example of the configuration of the acoustic signal output device 600.

[0060] Figure 47 This is a diagram showing an example of the configuration of the acoustic signal output device 600.

[0061] Figure 48 This is a diagram showing an example of the acoustic signal output device 600 having a frame.

[0062] Figure 49 This is a diagram showing an example of the configuration of the acoustic signal output device 700.

[0063] Figure 50 This is a diagram showing an example of the configuration of the acoustic signal output device 700.

[0064] Figure 51 This is a diagram showing an example of the acoustic signal output device 700 having an annular collar with a lighting function.

[0065] Figure 52 This is a diagram showing an example of the configuration of the acoustic signal output device 700. Detailed Embodiments

[0066] Hereinafter, embodiments of the present invention will be described in detail. In addition, structural parts having the same function are denoted by the same reference numerals and repeated description is omitted.

[0067] <First Embodiment>

[0068] A device that plays an acoustic signal obtained based on a playback object is called an acoustic signal output device. That is, the acoustic signal output device is a device that plays the input acoustic signal as sound (hereinafter, this sound is called the sound based on the acoustic signal), and includes a speaker unit. Here, the speaker unit is a device that converts an acoustic signal into sound. In addition, the playback object is data, a signal such as acoustic signal data that can be obtained by performing a prescribed process, for example, data recorded on a CD, DVD, or memory; data received via the Internet; signals received via radio or television broadcasts.

[0069] Here, an acoustic signal output device that plays an acoustic signal in such a way that only a user near the speaker unit can hear the sound based on the acoustic signal obtained from the playback object will be described. That is, users other than those near the speaker unit cannot hear the playback sound of the acoustic signal output device. When using such an acoustic signal output device as an acoustic system for a user of a seat in an aircraft, for example, a system in which only the user of that seat can hear the playback sound can be provided. In addition, such an acoustic system can be installed in seats, recliners, etc. of transportation means other than aircraft, such as cars and trains, and can also be installed in a wearable manner, such as on the shoulder.

[0070] As Figure 1 shown, the sound played from the speaker unit in the front direction of the speaker unit is called the in-phase sound, and the sound played from the speaker unit in the back direction of the speaker unit is called the out-of-phase sound. The out-of-phase sound is a sound with a phase opposite to that of the in-phase sound, that is, a sound with a phase obtained by reversing the phase of the in-phase sound by 180 degrees, and the in-phase sound and the out-of-phase sound are in an anti-phase relationship. In addition, the direction perpendicular to the front direction and the back direction is called the side direction.

[0071] Hereinafter, the acoustic signal output device 100 will be described with reference to Figures 2 to 8 FIGs. Figure 2 and Figure 3 are diagrams showing the configuration of the acoustic signal output device 100. Figure 2 is a diagram showing the state of observing the acoustic signal output device 100 from the side direction. Figure 3 is a diagram showing the state of observing the acoustic signal output device 100 from the front direction. As Figure 2 shown, the acoustic signal output device 100 includes a speaker unit 111 and a collar 112. The speaker unit 111 is a component including a diaphragm (not shown) that converts an acoustic signal into vibrations of air (i.e., generates sound waves). That is, the speaker unit 111 is a component that plays the input acoustic signal as sound. The collar 112 is a housing that houses a part of the speaker unit 111. In addition, Figure 2 in FIG., since a part of the speaker unit 111 (the part housed in the collar 112) cannot be seen from the side direction, it is shown by a dashed line. In addition, in Figure 2 FIG., the parts of the speaker unit 111 that play the in-phase sound and the out-of-phase sound, and the shape of the collar 112 are conical and bowl-shaped, respectively.

[0072] In addition, the plane that becomes the front of the speaker unit 111 and the plane that becomes the front of the collar 112 are preferably substantially parallel as Figure 2 shown. In Figure 2 FIG., these two planes are substantially the same.

[0073] The collar 112 is provided with a housing for causing the out-of-phase sound, i.e., the sound played from the speaker unit 111 toward the back side of the speaker unit 111, to bypass to the front side of the speaker unit 111, and holes (hereinafter referred to as first out-of-phase sound playback holes) for playing the out-of-phase sound that has bypassed to the collar 112 toward the front side of the speaker unit 111. Further, in Figure 2 Since the first out-of-phase sound playback holes cannot be seen from the side direction, they are shown by dashed lines.

[0074] Figure 4 FIG. is a diagram showing a case where the acoustic signal output device 100 plays a in-phase sound and an out-of-phase sound. More specifically, the acoustic signal output device 100 plays the in-phase sound from the speaker unit 111 toward the front side of the speaker unit 111, and plays the out-of-phase sound from the first out-of-phase sound playback holes toward the front side of the speaker unit 111. At this time, in order for only the users located near the speaker unit 111 to hear the sound and for other users not to hear the sound, it is preferable that the in-phase sound and the out-of-phase sound have a substantially out-of-phase relationship on the plane that is the front side of the speaker unit 111. That is, it is preferable that the sound played from the speaker unit 111 toward the front side of the speaker unit 111, i.e., the in-phase sound, and the out-of-phase sound played from the first out-of-phase sound playback holes toward the front side of the speaker unit 111 have a substantially out-of-phase relationship. More specifically, it is preferable that in a specified frequency band in the front direction of the speaker unit 111, the in-phase sound played from the speaker unit 111 toward the front side of the speaker unit 111 and the out-of-phase sound played from the first out-of-phase sound playback holes toward the front side of the speaker unit 111 have a substantially out-of-phase relationship. Here, the specified frequency band is preferably a frequency band below the frequency (hereinafter referred to as the resonance frequency) caused by the resonance of the internal space of the collar 112 generated between the speaker unit 111.

[0075] Therefore, the collar 112 houses a part of the speaker unit 111 in such a manner that in a specified frequency band in the front direction of the speaker unit 111, the path from the hole of the speaker unit 111 for playing the out-of-phase sound to the first out-of-phase sound playback holes is shortened, and the resonance frequency of the internal space of the collar 112 generated between the speaker unit 111 is increased, so that the out-of-phase sound played from the first out-of-phase sound playback holes toward the front side of the speaker unit 111 and the in-phase sound played from the speaker unit 111 toward the front side of the speaker unit 111 have a substantially out-of-phase relationship. In order to shorten the path from the hole of the speaker unit 111 for playing the out-of-phase sound to the first out-of-phase sound playback holes, when the speaker unit 111 is a speaker unit for a dynamic speaker, it is sufficient not to house the magnet part constituting the speaker unit 111 in the collar 112. Further, in order to increase the resonance frequency of the internal space of the collar 112 generated between the speaker unit 111, only by considering the resonance frequency f of the Helmholtz resonance HRegarding the following formula, by using one or more of the three methods of increasing the area S of the first out-of-phase sound emission hole, reducing the volume V of the internal space, and shortening the length L of the first out-of-phase sound emission hole to adjust the resonance frequency, it is sufficient to house a part of the speaker unit 111 in the collar 112 (see Figure 5 ).

[0076] Formula 1

[0077]

[0078] Among them, c represents the speed of sound.

[0079] Regarding the sound in the low-frequency region output by the acoustic signal output device 100, the farther away from the speaker unit, the more difficult it is to hear. This is because in the high-frequency region, when far away from the speaker unit, since the phases of the out-of-phase sound and the in-phase sound are inconsistent, they do not cancel each other out. However, in the low-frequency region, even when far away from the speaker unit, the phases of the out-of-phase sound and the in-phase sound are relatively consistent and can cancel each other out. Therefore, by installing a component (hereinafter referred to as a baffle) for adjusting the position where the out-of-phase sound and the in-phase sound cancel each other out in the low-frequency region to a position far away from the speaker unit on the speaker unit, the position of the sweet spot desired in the front direction of the speaker unit is adjusted (see Figure 6 ). That is, a baffle 113 can also be installed on the speaker unit 111. The baffle 113 is a component that prevents the out-of-phase sound emitted from the first out-of-phase sound emission hole and the in-phase sound emitted from the speaker unit 111 from canceling each other out at the position of the sweet spot desired in the front direction of the speaker unit 111. Figure 7 , Figure 8 Both are diagrams showing the configuration of the acoustic signal output device 100. Figure 7 is a diagram showing the acoustic signal output device 100 as viewed from the side direction. Figure 8 is a diagram showing the acoustic signal output device 100 as viewed from the front direction.

[0080] Figure 7 In, the parts of the speaker unit 111 that emit the in-phase sound and the out-of-phase sound, the shape of the collar 112, and the shape of the baffle 113 are conical, bowl-shaped, and plate-shaped, respectively.

[0081] In addition, the plane that is the front of the speaker unit 111, the plane that is the front of the collar 112, and the plane that is the front of the baffle 113 are preferably substantially parallel as shown in Figure 7 . In Figure 7 , these three planes are substantially the same.

[0082] According to the embodiment of the present invention, it is possible to increase the sweet spot in a limited area near the speaker unit.

[0083] (Variant Example 1)

[0084] As shown Figure 9 in the figure, holes different from the first out-of-phase sound emission holes (hereinafter referred to as second out-of-phase sound emission holes) through which the out-of-phase sound is emitted in a direction other than the front direction of the speaker unit 111 (i.e., the side direction and the back direction) by the collar 112 can also be provided. Figure 9 FIG. is a view showing a case where the acoustic signal output device 100 is observed from the side direction. The second out-of-phase sound emission holes can have any shape as long as they are holes for releasing the out-of-phase sound to the outside of the collar 112. For example, the shape of the second out-of-phase sound emission holes can also be a cutout shape (see Figure 9 (A)). In addition, the second out-of-phase sound emission holes can be provided at regular intervals on the side surface of the collar 112 (see Figure 9 (B)).

[0085] By causing the out-of-phase sound to be emitted from the second out-of-phase sound emission holes to the outside of the collar 112, the sound pressure of the out-of-phase sound can be released in a direction other than the front direction of the speaker unit 111, and the wave characteristics of the out-of-phase sound emitted from the first out-of-phase sound emission holes are changed. By suppressing the cancellation of the out-of-phase sound and the in-phase sound in the front direction of the speaker unit 111, the size and directivity of the sweet spot in the front direction of the speaker unit 111 can be controlled.

[0086] (Modification 2)

[0087] As shown Figure 10 in the figure, the collar 112 can also include a cylindrical member extending in the front direction of the speaker unit 111 from the plane that forms the front of the speaker unit 111, or can be in a shape that extends in a cylindrical shape in the front direction of the speaker unit 111 from the plane that forms the front of the speaker unit 111. Figure 10 FIG. is a view showing a case where the acoustic signal output device 100 is observed from the side direction. For example, when observed from the front of the speaker unit 111, the shapes of the diaphragm of the speaker unit 111 and the collar 112 are both substantially circular, and their centers are substantially the same. The collar 112 can also include a substantially cylindrical member extending in the front direction of the speaker unit 111 from the plane that forms the front of the speaker unit 111, or can be in a shape that extends in a substantially cylindrical shape in the front direction of the speaker unit 111 from the plane that forms the front of the speaker unit 111.

[0088] When the above-described collar 112 is used, since sound is less likely to leak outside the collar 112, sound leakage to the back direction of the speaker unit 111 can be suppressed.

[0089] (Modification 3)

[0090] As shown Figure 11As shown, the baffle 113 may also have a cylindrical member extending from the plane that is the front of the speaker unit 111 in the front direction of the speaker unit 111, or may be in a shape that extends in a cylindrical shape from the plane that is the front of the speaker unit 111 in the front direction of the speaker unit 111. Figure 11 FIG. Figure 11 shows a view of the acoustic signal output device 100 as viewed from the side direction. For example, when viewed from the front of the speaker unit 111, the shape of the diaphragm of the speaker unit 111 and the baffle 113 are both approximately circular, and their centers are approximately the same. The baffle 113 may also have a substantially cylindrical member extending from the plane that is the front of the speaker unit 111 in the front direction of the speaker unit 111, or may be in a shape that extends in a substantially cylindrical shape from the plane that is the front of the speaker unit 111 in the front direction of the speaker unit 111.

[0091] When using the above baffle 113, since the out-of-phase sound and the in-phase sound converge at a farther position in the front direction of the speaker unit 111, the sweet spot in the front direction of the speaker unit 111 can be located at a position farther from the speaker unit 111.

[0092] (Modification Example 4)

[0093] As Figure 12 shown, when viewed from the front of the speaker unit 111, the shape of the diaphragm of the speaker unit 111 may be approximately circular, the shape of the collar 112 when viewed from the front of the speaker unit 111 may be approximately elliptical, and the center of the diaphragm of the speaker unit 111 and the center of the collar 112 when viewed from the front of the speaker unit 111 are approximately the same. Figure 12 FIG. Figure 12 shows a view of the acoustic signal output device 100 as viewed from the front direction.

[0094] When using the above collar 112, the size of the collar 112 when viewed from the front of the speaker unit 111 can be made larger in the major axis direction, suppressing sound leakage in the back direction of the speaker unit 111.

[0095] (Modification Example 5)

[0096] As Figure 13 shown, when viewed from the front of the speaker unit 111, the shape of the diaphragm of the speaker unit 111 may be approximately circular, the shape of the collar 112 and the baffle 113 when viewed from the front of the speaker unit 111 may be approximately elliptical, and the center of the diaphragm of the speaker unit 111, the center of the collar 112, and the center of the baffle 113 when viewed from the front of the speaker unit 111 are approximately the same. In addition, the major axis direction of the collar 112 and the major axis direction of the baffle 113 when viewed from the front of the speaker unit 111 may be substantially parallel. Figure 13This is a view showing the acoustic signal output device 100 as observed from the front direction.

[0097] When using the above-mentioned collar 112 and baffle 113, the sweet spot can be increased in the major axis direction of the baffle 113 when observed from the front of the speaker unit 111.

[0098] (Modification Example 6)

[0099] As Figure 14 shown, an anti-vibration material, which is a component for suppressing the vibration of the collar 112, can also be installed on the collar 112. Figure 14 This is a view showing the acoustic signal output device 100 as observed from the side direction. As a component for suppressing the vibration of the collar 112, a sound-absorbing material, which is a component having sound-absorbing characteristics, can also be used.

[0100] By installing the anti-vibration material, it is possible to prevent the vibration of the collar from causing sound leakage.

[0101] (Modification Example 7)

[0102] When the shape of the diaphragm of the speaker unit 111 and the shape of the collar 112 are each approximately circular when observed from the front of the speaker unit 111, and the center of the diaphragm of the speaker unit 111 and the center of the collar 112 are approximately the same when observed from the front of the speaker unit 111, according to the characteristics of the shape of a circle, that is, the characteristic that the distance from the center of the circle to a point on the circumference is equal, the valleys of resonance in the high-frequency region and the mid-frequency region in the front direction of the speaker unit 111 become sharp, and sometimes the change in the sound volume in the high-frequency region and the mid-frequency region accompanying the movement of the user's head is noticed. Therefore, the shape of the collar 112 when observed from the front of the speaker unit 111 can also be made approximately square so that the valleys of resonance in the high-frequency region and the mid-frequency region become gentle. That is, the shape of the diaphragm of the speaker unit 111 when observed from the front of the speaker unit 111 is approximately circular, the shape of the collar 112 when observed from the front of the speaker unit 111 is approximately square, and the center of the diaphragm of the speaker unit 111 and the center of the collar 112 are approximately the same when observed from the front of the speaker unit 111 (see Figure 15 (A)). By making the shape of the collar approximately square, the distance from the center to a point on the side changes. Thereby, it is possible to suppress the change in the sound volume in the high-frequency region and the mid-frequency region accompanying the movement of the user's head, and it is possible to suppress the inaudibility and discomfort.

[0103] In addition, the center of the diaphragm of the speaker unit 111 and the center of the collar 112 can also be displaced by a predetermined distance when observed from the front of the speaker unit 111 (see Figure 15 (B)). In this way, it is possible to further suppress the inaudibility and discomfort.

[0104] In addition, Figure 15 FIG. is a view showing the acoustic signal output device 100 as viewed from the front direction.

[0105] (Experimental results)

[0106] When a part of the speaker unit is housed in the collar as in the acoustic signal output device 100, the sweet spot can be increased compared to the technology of Patent Document 1. Here, an experiment for verifying the performance related to the sound leakage of the acoustic signal output device 100 will be described. For the acoustic signal output device 100 (refer to Figure 16 (A)), an acoustic signal output device including only the speaker unit (refer to Figure 16 (B)), and an acoustic signal output device including the speaker unit and a closed speaker box (refer to Figure 16 (C)), the performance related to sound leakage is compared and verified.

[0107] Figure 17 The experimental results are shown. Figure 17 (A), Figure 17 (B), Figure 17 (C) are views showing the sound leakage of the acoustic signal output device 100, the acoustic signal output device including only the speaker unit, and the acoustic signal output device including the speaker unit and a closed speaker box, respectively. The horizontal axis is the frequency (unit: Hz), and the vertical axis is the sound pressure level (SPL (Sound Pressure Level), unit: dB). As shown in the figure, in the acoustic signal output device 100, when comparing the sound pressure levels in three directions, it can be seen that the sound leakage is suppressed to the same extent in the side direction and the back direction. In addition, it can be seen that in the acoustic signal output device including only the speaker unit, the sound leakage in the back direction is not sufficiently suppressed, and in the acoustic signal output device including the speaker unit and a closed speaker box, the sound leakage in the side direction is not sufficiently suppressed. Therefore, in the acoustic signal output device 100, in the front direction where the user is located, the sound can be clearly heard. On the other hand, in the side direction and the back direction, it is difficult to hear the sound, and it has a preferable property as an acoustic signal output device for only allowing the user to hear.

[0108] <Second Embodiment>

[0109] In the first embodiment, in order to suppress the sound leakage in the side direction and the back direction, a collar for housing a part of the speaker unit is used. However, since it has a shape that covers the speaker unit from the side direction, resonance that causes phase inversion of the anti-phase sound may sometimes occur. Therefore, in the present embodiment, a method of using a component with an open side direction instead of the collar will be described.

[0110] Hereinafter, refer toFigures 18 to 23 Describe the acoustic signal output device 200. Figure 18 , Figure 19 These are all diagrams showing the configuration of the acoustic signal output device 200. Figure 18 This is a diagram showing the acoustic signal output device 200 as viewed from the side direction. Figure 19 This is a diagram showing the acoustic signal output device 200 as viewed from the front direction. As Figure 18 shown, the acoustic signal output device 200 includes a speaker unit 111 and a collar baffle 212. The collar baffle 212 is a component mounted on the speaker unit 111. In addition, in Figure 18 , the parts that play the in-phase sound and the out-of-phase sound of the speaker unit 111, and the shape of the collar baffle 212 are conical and plate-shaped, respectively.

[0111] In addition, the plane that forms the front of the speaker unit 111 and the plane that forms the front of the collar baffle 212 are preferably substantially parallel as Figure 18 shown.

[0112] The collar baffle 212 is a component for redirecting the out-of-phase sound, which is the sound played from the speaker unit 111 towards the back direction of the speaker unit 111, to the front direction of the speaker unit 111. The collar baffle 212 is a component with a shape that opens the front direction and the side direction of the speaker unit 111, so that the redirected out-of-phase sound is played towards the front direction and the side direction of the speaker unit 111. By using the collar baffle 212, which is a component with a shape that opens the side direction of the speaker unit 111, resonance that causes phase inversion of the out-of-phase sound can be prevented.

[0113] Figure 20 These are diagrams showing the acoustic signal output device 200 playing the in-phase sound and the out-of-phase sound. More specifically, the acoustic signal output device 200 plays the in-phase sound from the speaker unit 111 towards the front direction of the speaker unit 111, and plays the out-of-phase sound from the opening between the speaker unit 111 and the collar baffle 212 towards the front direction and the side direction of the speaker unit 111. At this time, in order to enable only the users in the vicinity of the speaker unit 111 to hear the sound and other users not to hear the sound, it is preferable that the in-phase sound and the out-of-phase sound are in a substantially anti-phase relationship on the plane that forms the front of the speaker unit 111. That is, it is preferable that the in-phase sound, which is the sound played from the speaker unit 111 towards the front direction of the speaker unit 111, and the out-of-phase sound played from the opening between the speaker unit 111 and the collar baffle 212 towards the front direction of the speaker unit 111 are in a substantially anti-phase relationship.

[0114] Similarly to the first embodiment, a component (hereinafter referred to as a baffle) for making the position where the inverted sound and the non-inverted sound cancel each other out in the low-frequency region away from the speaker unit may be installed on the speaker unit, thereby adjusting the position of the sweet spot in the front direction of the speaker unit (see Figure 21 ). That is, a baffle 113 may be installed on the speaker unit 111. The baffle 113 is a component that prevents the inverted sound played from the opening between the speaker unit 111 and the collar baffle 212 and the non-inverted sound played from the speaker unit 111 from canceling each other out at the position of the sweet spot in the front direction of the speaker unit 111. Figure 22 , Figure 23 are diagrams showing the configuration of the acoustic signal output device 200. Figure 22 is a diagram showing the acoustic signal output device 200 as viewed from the side direction. Figure 23 is a diagram showing the acoustic signal output device 200 as viewed from the front direction. At this time, the size of the baffle 113 as viewed from the front of the speaker unit 111 may be smaller than the size of the collar baffle 212 as viewed from the front of the speaker unit 111. In addition, the size of the baffle 113 as viewed from the front of the speaker unit 111 may also be adjusted by the user to change the position of the sweet spot in the front direction of the speaker unit 111. Furthermore, the adjustable range of the user may be a range not exceeding the size of the collar baffle 212 as viewed from the front of the speaker unit 111.

[0115] In Figure 22 , the portions for playing the non-inverted sound and the inverted sound of the speaker unit 111, the collar baffle 212, and the baffle 113 are conical, plate-shaped, and plate-shaped, respectively.

[0116] In addition, the plane that is the front of the speaker unit 111, the plane that is the front of the collar baffle 212, and the plane that is the front of the baffle 113 are preferably substantially parallel as Figure 22 shown. In Figure 22 , the plane that is the front of the speaker unit 111 and the plane that is the front of the baffle 113 are substantially the same.

[0117] According to the embodiment of the present invention, it is possible to increase the sweet spot in a limited area near the speaker unit.

[0118] (Modification 1)

[0119] As Figure 24 shown, holes (hereinafter referred to as inverted sound playback holes) for playing the inverted sound toward the back direction of the speaker unit 111 may be provided in the collar baffle 212. Figure 24FIG. 0 is a view showing the acoustic signal output device 200 as viewed from the back direction. The shape of the out-of-phase sound emission hole can be arbitrary as long as it is used to release the out-of-phase sound outside the collar baffle 212. For example, the shape of the out-of-phase sound emission hole can also be a notch shape (see Figure 24 FIG. (A)). In addition, out-of-phase sound emission holes can be provided at regular intervals in the collar baffle 212 (see Figure 24 FIG. (B)).

[0120] By emitting the out-of-phase sound from the out-of-phase sound emission hole outside the collar baffle 212, the sound pressure of the out-of-phase sound can be released in the back direction of the speaker unit 111, and the wave characteristics of the out-of-phase sound emitted from the opening between the speaker unit 111 and the collar baffle 212 change. By suppressing the cancellation of the out-of-phase sound and the in-phase sound in the front direction of the speaker unit 111, the size and directivity of the sweet spot in the front direction of the speaker unit 111 can be controlled.

[0121] (Modification 2)

[0122] As shown in Figure 25 , the collar baffle 212 may have a cylindrical member extending from the plane that is the front surface of the collar baffle 212 in the front direction of the speaker unit 111, or may be in a shape that extends in a cylindrical shape from the plane that is the front surface of the collar baffle 212 in the front direction of the speaker unit 111. However, the length of the above-mentioned cylinder is such that the opening in the side direction of the speaker unit 111 is maintained. Figure 25 FIG. 17 is a view showing the acoustic signal output device 200 as viewed from the side direction. For example, when viewed from the front of the speaker unit 111, the shapes of the diaphragm of the speaker unit 111 and the collar baffle 212 are both substantially circular, and their centers are substantially the same. The collar baffle 212 may also have a substantially cylindrical member extending from the plane that is the front surface of the collar baffle 212 in the front direction of the speaker unit 111, or may be in a shape that extends in a substantially cylindrical shape from the plane that is the front surface of the collar baffle 212 in the front direction of the speaker unit 111.

[0123] When using the above-mentioned collar baffle 212, it is difficult for sound to leak outside the collar baffle 212, so sound leakage in the back direction of the speaker unit 111 can be suppressed.

[0124] (Modification 3)

[0125] As shown in Figure 26 , the baffle 113 may have a cylindrical member extending from the plane that is the front surface of the speaker unit 111 in the front direction of the speaker unit 111, or may be in a shape that extends in a cylindrical shape from the plane that is the front surface of the speaker unit 111 in the front direction of the speaker unit 111. Figure 26FIG. 0 is a view showing the acoustic signal output device 200 as observed from the side direction. For example, when viewed from the front of the speaker unit 111, the diaphragm and the baffle 113 of the speaker unit 111 are both approximately circular in shape, and their centers are approximately the same. The baffle 113 may also include a substantially cylindrical member extending in the front direction of the speaker unit 111 from the plane that is the front of the speaker unit 111, or may be in a shape that extends in a substantially cylindrical shape in the front direction of the speaker unit 111 from the plane that is the front of the speaker unit 111.

[0126] When using the above baffle 113, since the out-of-phase sound and the in-phase sound merge at a farther position in the front direction of the speaker unit 111, the sweet spot in the front direction of the speaker unit 111 can be located at a position farther from the speaker unit 111.

[0127] (Modification Example 4)

[0128] As Figure 27 shown, when viewed from the front of the speaker unit 111, the shape of the diaphragm of the speaker unit 111 may be approximately circular, the shape of the collar baffle 212 when viewed from the front of the speaker unit 111 may be approximately elliptical, and the center of the diaphragm of the speaker unit 111 and the center of the collar baffle 212 when viewed from the front of the speaker unit 111 are approximately the same. Figure 27 FIG. 13 is a view showing the acoustic signal output device 200 as observed from the front direction.

[0129] When using the above collar baffle 212, the size of the collar baffle 212 when viewed from the front of the speaker unit 111 increases in the major axis direction, and leakage sound in the back direction of the speaker unit 111 can be suppressed.

[0130] (Modification Example 5)

[0131] As Figure 28 shown, when viewed from the front of the speaker unit 111, the shape of the diaphragm of the speaker unit 111 may be approximately circular, the shape of the collar baffle 212 and the shape of the baffle 113 when viewed from the front of the speaker unit 111 may be approximately elliptical, and the center of the diaphragm of the speaker unit 111, the center of the collar baffle 212, and the center of the baffle 113 when viewed from the front of the speaker unit 111 are approximately the same. In addition, the major axis direction of the collar baffle 212 and the major axis direction of the baffle 113 when viewed from the front of the speaker unit 111 may be approximately parallel. Figure 28 FIG. 26 is a view showing the acoustic signal output device 200 as observed from the front direction.

[0132] When using the above-mentioned collar baffle 212 and baffle 113, the sweet spot can be increased in the major axis direction of the baffle 113 when viewed from the front of the speaker unit 111.

[0133] (Modification Example 6)

[0134] As Figure 29 shown, a vibration suppression member, i.e., a vibration-proof material, can also be installed on the collar baffle 212. Figure 29 FIG. is a view showing the acoustic signal output device 200 when viewed from the side direction. As a member for suppressing the vibration of the collar baffle 212, a member having sound absorption characteristics, i.e., a sound absorption material, can also be used.

[0135] By installing the vibration-proof material, it is possible to prevent the vibration of the collar baffle from causing sound leakage.

[0136] (Modification Example 7)

[0137] Similar to Modification Example 7 of the first embodiment, the shape of the diaphragm of the speaker unit 111 when viewed from the front of the speaker unit 111 can be substantially circular, the shape of the collar baffle 212 when viewed from the front of the speaker unit 111 can be substantially square, and the center of the diaphragm of the speaker unit 111 and the center of the collar baffle 212 when viewed from the front of the speaker unit 111 can be substantially the same (see Figure 30 (A)). By making the shape of the collar substantially square, the distance from the center to the points on the side changes. As a result, the change in the sound volume in the high-frequency region and the mid-frequency region accompanying the movement of the user's head is suppressed, and the difficulty of hearing and discomfort can be suppressed.

[0138] In addition, the center of the diaphragm of the speaker unit 111 and the center of the collar baffle 212 when viewed from the front of the speaker unit 111 can also be offset by a predetermined distance (see Figure 30 (B)). In this way, the difficulty of hearing and discomfort can be further suppressed.

[0139] In addition, Figure 30 FIG. is a view showing the acoustic signal output device 200 when viewed from the front direction.

[0140] (Experimental Results)

[0141] Here, an experiment for verifying the performance related to the sound leakage of the acoustic signal output device 200 will be described. For the acoustic signal output device 200 with a small baffle size (see Figure 31 (A)), the acoustic signal output device 200 with a medium baffle size (see Figure 31 (B)), and the acoustic signal output device 200 with a large baffle size (see Figure 31The performance related to sound leakage of (C) is compared and verified. When observing from the front of the speaker unit, the shapes of the baffle plates and collar baffle plates of each acoustic signal output device 200 are square. Here, the baffle plate size and the collar baffle plate size are the lengths of one side of the square. The baffle plate sizes of each acoustic signal output device 200 are 9 cm, 13 cm, and 17 cm, and the collar baffle plate sizes are all 17 cm.

[0142] Figure 32 Shows the experimental results. Figure 32 (A), Figure 32 (B), Figure 32 (C) are diagrams showing the sound leakage situations of the acoustic signal output device 200 with a smaller baffle plate size, the acoustic signal output device 200 with a medium baffle plate size, and the acoustic signal output device 200 with a larger baffle plate size, respectively. The horizontal axis is the frequency (unit: Hz), and the vertical axis is the sound pressure level (SPL (Sound Pressure Level), unit: dB). Comparing the three diagrams, it can be seen that in order to reduce sound leakage in the side direction and the back direction, it is known that it is preferable that the size of the baffle plate is smaller than the size of the collar baffle plate.

[0143] <Third Embodiment>

[0144] In the first embodiment, since only one speaker unit is used, the sweet spot is sometimes narrow. Therefore, in this embodiment, a method of using multiple speaker units will be described.

[0145] Hereinafter, with reference to Figures 33 to 36 The acoustic signal output device 300 will be described. Figure 33 , Figure 34 are all diagrams showing the configuration of the acoustic signal output device 300, Figure 33 is a diagram showing the situation of observing the acoustic signal output device 300 from the side direction, Figure 34 is a diagram showing the situation of observing the acoustic signal output device 300 from the front direction. As Figure 33 shown, the acoustic signal output device 300 includes a speaker unit pair 311 composed of two speaker units 111, a collar 312, and a baffle plate 313. The acoustic characteristics of the two speaker units 111 constituting the speaker unit pair 311 are substantially the same, and the same acoustic signal is input. In addition, the fronts of the two speaker units 111 constituting the speaker unit pair 311 are, for example, on substantially the same plane. The collar 312 is a frame for housing a part of the speaker unit pair 311. In addition, in Figure 33 , since a part of the speaker unit 111 (the part housed in the collar 312) cannot be seen from the side direction, it is depicted with a dashed line. In addition, in Figure 33In this case, the portions of the speaker unit 111 that play the in-phase sound and the out-of-phase sound, the shape of the collar 312, and the shape of the baffle 313 are conical, elongated bowl-shaped, and plate-shaped, respectively.

[0146] In addition, the plane that is the front surface of the speaker unit pair 311, the plane that is the front surface of the collar 312, and the plane that is the front surface of the baffle 313 are preferably substantially parallel as Figure 33 shown. In Figure 33 this case, these three planes are substantially the same.

[0147] The collar 312 is a frame for causing the out-of-phase sound, which is the sound played from the two speaker units 111 constituting the speaker unit pair 311 toward the back surface direction of the speaker unit pair 311, to bypass to the front surface direction of the speaker unit pair 311. A hole for playing the bypassed out-of-phase sound toward the front surface direction of the speaker unit pair 311 (hereinafter referred to as the first out-of-phase sound playback hole) is provided in the collar 312. In addition, in Figure 33 this case, since the first out-of-phase sound playback hole cannot be seen from the side direction, it is depicted by a dashed line.

[0148] Figure 35 FIG. is a diagram showing a case where the acoustic signal output device 300 plays the in-phase sound and the out-of-phase sound. More specifically, the acoustic signal output device 300 plays the in-phase sound from the speaker unit 111 toward the front surface direction of the speaker unit pair 311, and plays the out-of-phase sound from the first out-of-phase sound playback hole toward the front surface direction of the speaker unit pair 311. At this time, in order for only the users near the speaker unit pair 311 to be able to hear the sound and for other users not to hear the sound, in the plane that is the front surface of the speaker unit 111, the in-phase sound and the out-of-phase sound are preferably in a substantially out-of-phase relationship. That is, it is preferable that the in-phase sound, which is the sound played from the speaker unit 111 toward the front surface direction of the speaker unit pair 311, and the out-of-phase sound played from the first out-of-phase sound playback hole toward the front surface direction of the speaker unit pair 311 are in a substantially out-of-phase relationship. More specifically, in a specified frequency band in the front surface direction of the speaker unit pair 311, it is preferable that the in-phase sound played from the speaker unit 111 toward the front surface direction of the speaker unit pair 311 and the out-of-phase sound played from the first out-of-phase sound playback hole toward the front surface direction of the speaker unit pair 311 are in a substantially out-of-phase relationship. Here, the specified frequency band is preferably a frequency band below the frequency (hereinafter referred to as the resonance frequency) caused by the resonance of the internal space of the collar 312 generated between the speaker unit pair 311 and the baffle 313.

[0149] Therefore, the collar 312 houses a part of the speaker unit 111 in such a way that the path from the hole of each speaker unit 111 constituting the speaker unit pair 311 for playing out-of-phase sound to the first out-of-phase sound playback hole is shortened, and the resonance frequency of the internal space of the collar 312 generated between the speaker unit pair 311 and the baffle 313 becomes higher, so that in a specified frequency band in the front direction of the speaker unit pair 311, the out-of-phase sound played from the first out-of-phase sound playback hole in the front direction of the speaker unit pair 311 and the in-phase sound played from the speaker unit 111 in the front direction of the speaker unit pair 311 are in a substantially out-of-phase relationship. In order to shorten the path from the hole of the speaker unit 111 for playing out-of-phase sound to the first out-of-phase sound playback hole, if the speaker unit 111 is a speaker unit for a dynamic speaker, it is sufficient that the magnet portion constituting the speaker unit 111 is not housed in the collar 312. In addition, in order to increase the resonance frequency of the internal space of the collar 312 generated between the speaker unit pair 311 and the baffle 313, similar to the first embodiment, considering the resonance frequency f H related to formula (1), one or more of the three methods of increasing the area S of the first out-of-phase sound playback hole, reducing the volume V of the internal space, and shortening the length L of the first out-of-phase sound playback hole are used to adjust the resonance frequency, and it is sufficient that the collar 312 houses a part of the speaker unit pair 311 (refer to Figure 36 ).

[0150] A baffle 313 is installed on the speaker unit pair 311. The baffle 313 is a component for preventing the out-of-phase sound played from the first out-of-phase sound playback hole and the in-phase sound played from the two speaker units 111 constituting the speaker unit pair 311 in the front direction of the speaker unit pair 311 from canceling each other out at the position that is intended to be the sweet spot in the front direction of the speaker unit pair 311. In addition, the baffle 313 is installed on the speaker unit pair 311 so that the area between the front directions of the respective speaker units 111 constituting the speaker unit pair 311 becomes the sweet spot. Therefore, for example, the baffle 313 is installed on the speaker unit pair 311 in such a way that the sides of the speaker unit pair 311 where one speaker unit 111 of the speaker unit pair 311 faces the other speaker unit 111 are connected to each other. Thus, in the speaker unit 111, the baffle 313 is installed on the side facing the other speaker unit 111, and the baffle 313 is not installed on the side opposite to the side facing the other speaker unit 111. Similar to the acoustic signal output device 100, leakage sound in the side direction and the back direction can be reduced. In addition, since the out-of-phase sound is redirected to the front direction of the speaker unit pair 311 by the collar 312, leakage sound in the high-frequency region in the back direction of the speaker unit pair 311 can be reduced.

[0151] According to an embodiment of the present invention, it is possible to increase the sweet spot in a limited area near the speaker unit. In addition, in Patent Document 1, it is possible to make the area between the front directions of the speaker units that are difficult to hear into a sweet spot.

[0152] (Modification Example 1)

[0153] Hereinafter, when observing the front of the speaker unit pair 311, the direction connecting the two speaker units 111 constituting the speaker unit pair 311 is referred to as the longitudinal direction of the baffle 313, and when observing the front of the speaker unit pair 311, the direction perpendicular to the direction connecting the two speaker units 111 constituting the speaker unit pair 311 is referred to as the lateral direction of the baffle 313 (refer to Figure 37 ).

[0154] As described above, the baffle 313 is attached to the speaker unit pair 311 so that the area between the front directions of the respective speaker units 111 constituting the speaker unit pair 311 becomes a sweet spot. The size of the sweet spot between the front directions of the respective speaker units 111 constituting the speaker unit pair 311 depends on the longitudinal length and the lateral length of the baffle 313. That is, when the longitudinal length of the baffle 313 is increased, the size of the sweet spot increases in the longitudinal direction, and when the lateral length of the baffle 313 is increased, the size of the sweet spot increases in the lateral direction. Therefore, the longitudinal length of the baffle 313 and the lateral length of the baffle 313 can also be determined according to the size of the area between the front directions of the respective speaker units 111 constituting the speaker unit pair 311 that is desired to be a sweet spot.

[0155] As Figure 38 shown, by setting the longitudinal length of the baffle 313 connecting the two speaker units 111 to be long and separating the two speaker units 111, it is possible to increase the sweet spot in the front direction of the speaker unit pair 311.

[0156] In addition, as Figure 39 shown, by arranging the baffle 313 in such a way that the lateral length of the baffle 313 is long with the collar 312 in contact with the baffle 313, it is possible to increase the sweet spot in the front direction of the speaker unit pair 311. At this time, the sweet spot can be set at a position farther from the front of the speaker unit pair 311.

[0157] (Modification Example 2)

[0158] As Figure 40 shown, it is also possible to arrange the respective speaker units 111 such that the planes forming the fronts of the respective speaker units 111 constituting the speaker unit pair 311 are not in the same plane. In Figure 40In the example, the two speaker units 111 are arranged such that the angle formed by the front directions of the two speaker units 111 is an acute angle smaller than 45 degrees.

[0159] (Modification Example 3)

[0160] As Figure 41 shown, the number of speaker units included in the acoustic signal output device 300 may also be 4, for example.

[0161] As in the above modification example, by adjusting the longitudinal length of the baffle 313, the lateral length of the baffle 313, the angle formed by the front directions of the two speaker units 111, and the number of speaker units included in the acoustic signal output device 300, the size of the sweet spot can be adjusted.

[0162] <Fourth Embodiment>

[0163] When using two acoustic signal output devices 100 to play a stereophonic signal, since the range where the sound of each channel can be heard is the same as the sweet spot of the acoustic signal output device 100, the size of the sweet spot is insufficient. In addition, when using two acoustic signal output devices 300 to play a stereophonic signal, since four speaker units are required, the space required for installation becomes larger. Therefore, in this embodiment, a method of playing a stereophonic signal using one acoustic signal output device 300, in which the sweet spot is larger than in the case of using two acoustic signal output devices 100, will be described.

[0164] Hereinafter, with reference to Figure 42 the acoustic signal output device 400 will be described. Figure 42 is a diagram showing the configuration of the acoustic signal output device 400. As Figure 42 shown, the acoustic signal output device 400 includes: a speaker unit pair 311 composed of two speaker units 111, a collar 312, a baffle 313, and an acoustic signal generation unit 420. That is, the acoustic signal output device 400 differs from the acoustic signal output device 300 only in that it further includes an acoustic signal generation unit 420. In addition, the acoustic signal generation unit 420 can be configured using a general-purpose computer, for example. By storing a program for implementing the function of the acoustic signal generation unit 420 in an external storage device, ROM, etc., reading the program and the data required for the processing of the program into the RAM as needed, and appropriately processing them by the CPU, the acoustic signal generation unit 420 is implemented using a general-purpose computer. That is, the acoustic signal generation unit 420 can also be configured using a processing circuit.

[0165] The acoustic signal generation unit 420 is a component that inputs the acoustic signal for the right channel and the acoustic signal for the left channel, generates a first output acoustic signal and a second output acoustic signal using the acoustic signal for the right channel and the acoustic signal for the left channel, outputs the first output acoustic signal to one speaker unit 111 that constitutes the speaker unit pair 311, and outputs the second output acoustic signal to the other speaker unit 111 that constitutes the speaker unit pair 311. The acoustic signal generation unit 420 may also output the input acoustic signal for the right channel and the acoustic signal for the left channel without performing signal processing on them as they are. That is, the first output acoustic signal is the acoustic signal for the right channel, and the second output acoustic signal is the acoustic signal for the left channel. Thus, in a normal stereo sound source, since the correlation between channels in the low-frequency region is relatively high, the sweet spot is enlarged, and leakage sound at a farther position in the front direction, as well as leakage sound in the side and back directions, is suppressed. On the other hand, in the high-frequency region, the lower the frequency, the lower the correlation between channels. However, since the sound in the high-frequency region has stronger directivity than the sound in the low-frequency region, leakage sound in the side and back directions is suppressed.

[0166] In addition, the acoustic signal generation unit 420 may also generate and output the first output acoustic signal and the second output acoustic signal as acoustic signals that enlarge the size of the sweet spot from the input acoustic signal for the right channel and the acoustic signal for the left channel. Therefore, the acoustic signal generation unit 420 performs signal processing to obtain a new acoustic signal by mixing the input acoustic signal for the right channel and the acoustic signal for the left channel, so as to generate the first output acoustic signal and the second output acoustic signal. For example, taking r (where 0 < r < 1) as the mixing coefficient, the acoustic signal generation unit 420 mixes the acoustic signal for the right channel and the acoustic signal for the left channel in the ratio of r:1 - r to obtain the acoustic signal as the first output acoustic signal, and mixes the acoustic signal for the right channel and the acoustic signal for the left channel in the ratio of 1 - r:r to obtain the acoustic signal as the second output acoustic signal. That is, according to the first output acoustic signal = acoustic signal for the right channel × r + acoustic signal for the left channel × (1 - r), and the second output acoustic signal = acoustic signal for the right channel × (1 - r) + acoustic signal for the left channel × r, the first output acoustic signal and the second output acoustic signal are generated. In addition, the mixing coefficient r may also be set as a value related to frequency, and different mixing coefficients may be used for each frequency.

[0167] According to the embodiment of the present invention, it is possible to enlarge the sweet spot in a limited area near the speaker unit. By inputting the acoustic signal for the right channel and the acoustic signal for the left channel, the sweet spot can be enlarged.

[0168] <Fifth Embodiment>

[0169] As shown in the first embodiment, in the low-frequency region, even when far from the speaker unit, since the phases of the out-of-phase sound and the in-phase sound are relatively consistent and cancel each other out, the sound in the low-frequency region may sometimes seem weak. Therefore, in the present embodiment, a method using a speaker unit for playing in the low-frequency region, i.e., a woofer, and a speaker unit for playing in the high-frequency region, i.e., a tweeter, will be described.

[0170] Hereinafter, with reference to Figures 43 to 45 the acoustic signal output device 500 will be described. Figure 43 , Figure 44 are diagrams showing the configuration of the acoustic signal output device 500. Figure 43 is a diagram showing the case of observing the acoustic signal output device 500 from the side direction. Figure 44 is a diagram showing the case of observing the acoustic signal output device 500 from the front direction. As Figure 43 shown, the acoustic signal output device 500 includes a first acoustic signal output unit 510 and a second acoustic signal output unit 520. The first acoustic signal output unit 510 includes a speaker unit for playing the sound in the low-frequency region, i.e., a woofer 511, and a first collar 512. The first collar 512 is a housing that houses a part of the woofer 511. In addition, the second acoustic signal output unit 520 includes a speaker unit for playing the sound in the high-frequency region, i.e., a tweeter 521, and a second collar 522. The second collar 522 is a housing that houses a part of the tweeter 521. Furthermore, in Figure 43 , a part of the woofer 511 (the part housed in the first collar 512) and a part of the tweeter 521 (the part housed in the second collar 522) cannot be seen from the side direction, so they are shown with dashed lines. In addition, in Figure 43 , the parts of the woofer 511 that play the in-phase sound and the out-of-phase sound and the shape of the first collar 512 are conical and bowl-shaped, respectively. Similarly, the parts of the tweeter 521 that play the in-phase sound and the out-of-phase sound and the shape of the second collar 522 are conical and bowl-shaped, respectively.

[0171] In addition, the plane that forms the front of the woofer 511 and the plane that forms the front of the first collar 512 are preferably substantially parallel as Figure 43 shown. Similarly, the plane that forms the front of the tweeter 521 and the plane that forms the front of the second collar 522 are also preferably substantially parallel as Figure 43 shown. In Figure 43 , these four planes are substantially the same.

[0172] The first ring 512 is a frame that redirects the sound played from the woofer 511 towards the back of the woofer 511, i.e., the out-of-phase sound (hereinafter referred to as the first out-of-phase sound), to the front direction of the woofer 511. In the first ring 512, there are holes (hereinafter referred to as the first out-of-phase sound playback holes) for playing the redirected first out-of-phase sound towards the front direction of the woofer 511. Additionally, the second ring 522 is a frame that redirects the sound played from the tweeter 521 towards the back of the tweeter 521, i.e., the out-of-phase sound (hereinafter referred to as the second out-of-phase sound), to the front direction of the tweeter 521. In the second ring 522, there are holes (hereinafter referred to as the second out-of-phase sound playback holes) for causing the redirected second out-of-phase sound to be played towards the front direction of the tweeter 521. Furthermore, in Figure 43 Since neither the first out-of-phase sound playback holes nor the second out-of-phase sound playback holes can be seen from the side direction, they are depicted with dashed lines.

[0173] The first ring 512 shortens the path from the hole of the woofer 511 for playing the first out-of-phase sound to the first out-of-phase sound playback holes, and houses a part of the woofer 511 in a form that increases the resonance frequency (hereinafter referred to as the resonance frequency) of the internal space of the first ring 512 generated between the woofers 511, so that in a specified frequency band in the front direction of the woofer 511, the first out-of-phase sound played from the first out-of-phase sound playback holes and the sound played from the woofer 511 towards the front direction of the woofer 511 (hereinafter referred to as the first in-phase sound) are in a substantially out-of-phase relationship. Additionally, the specified frequency band is preferably a frequency band below the resonance frequency of the internal space of the first ring 512 generated between the woofers 511. When the path from the hole of the woofer 511 for playing the first out-of-phase sound to the first out-of-phase sound playback holes becomes short, as long as the woofer 511 is a woofer for a dynamic speaker, the magnet part constituting the woofer 511 does not need to be housed in the first ring 512. Also, when the resonance frequency of the internal space of the first ring 512 generated between the woofers 511 increases, considering the resonance frequency f of Helmholtz resonance HRegarding the related formula (1), one or more of the three methods of increasing the area S of the first out-of-phase sound emission hole, decreasing the volume V of the internal space, and shortening the length L of the first out-of-phase sound emission hole can be used to adjust the resonance frequency, and it is sufficient to accommodate a part of the bass speaker 511 in the first collar 512. Additionally, the second collar 522 is configured such that the path from the hole of the tweeter 521 for emitting the second out-of-phase sound to the second out-of-phase sound emission hole is shortened, and the resonance frequency (hereinafter referred to as the resonance frequency) caused by the resonance of the internal space of the second collar 522 generated between the tweeters 521 becomes higher, and a part of the tweeter 521 is accommodated so that in a specified frequency band in the front direction of the tweeter 521, the second out-of-phase sound emitted from the second out-of-phase sound emission hole and the sound (hereinafter referred to as the second in-phase sound) emitted from the tweeter 521 in the front direction of the tweeter 521 are in a substantially out-of-phase relationship. Furthermore, the specified frequency band is preferably a frequency band below the resonance frequency of the internal space of the second collar 522 generated between the tweeters 521. When the path from the hole of the tweeter 521 for emitting the second out-of-phase sound to the second out-of-phase sound emission hole is shortened, as long as the tweeter 521 is a tweeter for a dynamic speaker, it is sufficient that the magnet portion constituting the tweeter 521 is not accommodated in the second collar 522. Additionally, when the resonance frequency of the internal space of the second collar 522 generated between the tweeters 521 becomes higher, considering the resonance frequency f of Helmholtz resonance H Regarding the related formula (1), one or more of the three methods of increasing the area S of the second out-of-phase sound emission hole, decreasing the volume V of the internal space, and shortening the length L of the second out-of-phase sound emission hole can be used to adjust the resonance frequency, and it is sufficient to accommodate a part of the tweeter 521 in the second collar 522.

[0174] The second acoustic signal output unit 520 is provided near the user's ear to suppress sound leakage. For example, there are two second acoustic signal output units 520, one for emitting the right-channel acoustic signal and the other for emitting the left-channel acoustic signal. In this case, it is sufficient to provide the second acoustic signal output unit 520 for emitting the right-channel acoustic signal near the user's right ear and the second acoustic signal output unit 520 for emitting the left-channel acoustic signal near the user's left ear.

[0175] Similar to the first embodiment, it is also possible to adjust the position where the out-of-phase sound and the in-phase sound cancel each other out in the low-frequency region to a position away from the woofer by installing a component (hereinafter referred to as a baffle) on the woofer, thereby adjusting the position of the sweet spot in the front direction of the woofer. That is, it is also possible to install a first baffle (not shown), which is a component that prevents the first out-of-phase sound played from the first out-of-phase sound playback hole and the first in-phase sound played from the woofer 511 from canceling each other out at the position of the sweet spot in the front direction of the woofer 511, on the woofer 511.

[0176] In addition, in order to suppress sound leakage in the side direction and the back direction, similar to the woofer, it is also possible to install a baffle on the tweeter. That is, it is also possible to install a second baffle (not shown), which is a component that suppresses sound leakage in the side direction and the back direction of the tweeter 521, on the tweeter 521.

[0177] Furthermore, when a speaker unit that plays sounds in the low-frequency region around 300 Hz is used as the woofer 511, the first acoustic signal output unit 510 having the first baffle can sufficiently obtain sounds in the low-frequency region near the woofer 511 by increasing the playback voltage. In addition, by using a speaker unit with a diameter of about 30 mm as the tweeter 521 and arranging the second acoustic signal output unit 520 having the second baffle at a position close to the user's ear, sound leakage can be suppressed.

[0178] Figure 45 This is an example of an in-vehicle acoustic signal output device 500 provided in the headrest of a seat in a vehicle. Figure 45 (A) shows the exposed state, Figure 45 and (B) shows the state with the cover on. As Figure 45 shown, the in-vehicle acoustic signal output device 500 has a large woofer arranged in the center, and small tweeters arranged at the lower right and lower left thereof. With this configuration, since there is a large woofer directly behind the user's head, cancellation of sounds in the low-frequency region can be suppressed, and the user can more easily hear sounds in the low-frequency region.

[0179] With the embodiments of the present invention, it is possible to increase the sweet spot in a limited area near the speaker unit. Through the two-way configuration of the woofer and the tweeter, the low-frequency region of the woofer can be enhanced. Specifically, by independently driving the woofer, which is used to play sounds in the low-frequency region with large cancellation and difficult to hear, and the tweeter, a larger voltage can be applied to the woofer compared to the tweeter, increasing the output of the woofer. In addition, by restricting the frequency band corresponding to the tweeter to the high-frequency region and reducing the size of the tweeter, and making the sound in the high-frequency region where it is difficult to suppress sound leakage play only near the user's ear, sound leakage can be suppressed.

[0180] <Sixth Embodiment>

[0181] When the acoustic signal output device 100 is set in a quiet space, i.e., a bedroom, it is convenient to be able to easily change the area where the sound can be heard so that the family members sleeping beside cannot hear it. Therefore, in this embodiment, the installation method of the component that can easily change the front direction of the acoustic signal output device 100 will be described.

[0182] Hereinafter, with reference to Figures 46 to 48 the acoustic signal output device 600 will be described. Figure 46 , Figure 47 are all diagrams showing the configuration of the acoustic signal output device 600, Figure 46 is a diagram showing the acoustic signal output device 600 as viewed from the side direction, Figure 47 is a diagram showing the acoustic signal output device 600 as viewed from the front direction. As Figure 46 shown, the acoustic signal output device 600 includes an acoustic signal output unit 610 and a direction adjustment unit 614. The acoustic signal output unit 610 includes a speaker unit 111 and a collar 112. The collar 112 is a frame that houses a part of the speaker unit 111.

[0183] The collar 112 is a frame for making the sound that is played from the speaker unit 111 in the back direction of the speaker unit 111, i.e., the out-of-phase sound, bypass to the front direction of the speaker unit 111. In the collar 112, there are holes (hereinafter referred to as the first out-of-phase sound playback holes) for playing the bypassed out-of-phase sound to the front direction of the speaker unit 111.

[0184] The collar 112 is accommodated in a form in which the path from the hole of the speaker unit 111 for playing out-of-phase sound to the first out-of-phase sound playing hole is shortened, and the resonance frequency (hereinafter referred to as the resonance frequency) caused by the resonance of the internal space of the collar 112 generated between the speaker units 111 becomes higher, so that in a specified frequency band in the front direction of the speaker unit 111, the out-of-phase sound played from the first out-of-phase sound playing hole toward the front direction of the speaker unit 111 and the in-phase sound played from the speaker unit 111 toward the front direction of the speaker unit 111 are in a substantially out-of-phase relationship. In addition, the specified frequency band is preferably a frequency band below the resonance frequency of the internal space of the collar 112 generated between the speaker units 111. When the path from the hole of the speaker unit 111 for playing out-of-phase sound to the first out-of-phase sound playing hole is shortened, as long as the speaker unit 111 is a speaker unit for a dynamic speaker, the magnet portion constituting the speaker unit 111 does not need to be provided in the collar 112. In addition, when the resonance frequency of the internal space of the collar 112 generated between the speaker units 111 becomes higher, considering the formula (1) related to the resonance frequency f H of Helmholtz resonance, one or more of the three methods of increasing the area S of the first out-of-phase sound playing hole, reducing the volume V of the internal space, and shortening the length L of the first out-of-phase sound playing hole are used to adjust the resonance frequency, and it is sufficient that the collar 112 accommodates a part of the speaker unit 111.

[0185] The direction adjustment unit 614 is a component mounted on the acoustic signal output unit 610 in order to change the front direction of the acoustic signal output unit 610. By adjusting the direction adjustment unit 614, the user can change the area where sound leakage is to be suppressed. The direction adjustment unit 614 may be a component such as the arm of a desk lamp (see Figure 46 ). In addition, the direction adjustment unit 614 may also be a component such as a frame mounted in a manner surrounding the periphery of the acoustic signal output unit 610 as shown in Figure 48 (A). In addition, the acoustic signal output device 600 may also include two or more acoustic signal output units 610. In this case, the direction adjustment unit 614 may also be mounted on each of the acoustic signal output units 610 to change the front direction of the acoustic signal output unit 610 (see Figure 48 (B)).

[0186] A region where no sound can be heard is formed in the side direction of the acoustic signal output unit 610. Therefore, when the front direction of the acoustic signal output unit 610 is changed using the direction adjustment unit 614 in such a manner that a user who does not want to hear sound is located in the side direction of the acoustic signal output unit 610, the user can not hear sound.

[0187] Similar to the first embodiment, it is also possible to adjust the position of the sweet spot in the front direction of the speaker unit by installing a component (hereinafter referred to as a baffle) that adjusts the position for canceling the inverted sound and the non-inverted sound in the low-frequency region to a position away from the speaker unit. That is, it is also possible to install a baffle 113, which is a component for preventing the inverted sound played from the first inverted sound playback hole and the non-inverted sound played from the speaker unit 111 from canceling each other at the position of the sweet spot in the front direction of the speaker unit 111.

[0188] According to the embodiment of the present invention, it is possible to increase the sweet spot in a limited area near the speaker unit. By adjusting the front direction of the acoustic signal output unit 610, the user can change the area where leakage sound is to be suppressed.

[0189] <Seventh Embodiment>

[0190] In the first embodiment, leakage sound in the back direction, especially in the high-frequency region, may be noticed. Therefore, in this embodiment, a method for suppressing leakage sound in the back direction will be described.

[0191] Hereinafter, with reference to Figures 49 to 52 the acoustic signal output device 700 will be described. Figure 49 , Figure 50 are diagrams showing the configuration of the acoustic signal output device 700, Figure 49 is a diagram showing the acoustic signal output device 700 as viewed from the layer direction, Figure 50 is a diagram showing the acoustic signal output device 700 as viewed from the front direction. As Figure 49 shown, the acoustic signal output device 700 includes a speaker unit 111, a collar 112, and an annular collar 714. The collar 112 is a frame for housing a part of the speaker unit 111. The annular collar 714 is a ring-shaped component having a size capable of covering the periphery in the side direction of the collar 112. The shape of the annular collar 714 may be arbitrary as long as it can cover the periphery in the side direction of the collar 112. The shape of the annular collar 714 when viewed from the front of the speaker unit 111 may be, for example, substantially circular or substantially elliptical. In addition, between the collar 112 and the annular collar 714, it is also possible to install a baffle (not shown), which is a component for filling the gap. In this case, leakage sound in the back direction of the speaker unit 111 can be suppressed. On the other hand, a gap may be provided between the collar 112 and the annular collar 714. In this case, sound can be transmitted from between the collar 112 and the annular collar 714 to the back direction of the speaker unit 111, and as a result, leakage sound can be suppressed. In addition, as Figure 51 shown, the annular collar 714 may also have an illumination function.

[0192] Alternatively, when viewed from the front of the speaker unit 111, for example, the shape of the diaphragm of the speaker unit 111 and the shape of the annular collar 714 are both approximately circular, and their centers are approximately the same. The annular collar 714 is arranged to be located in the side direction of the speaker unit 111 (see Figure 49 ), and it can also be arranged to be located in the front direction of the speaker unit 111 when viewed from the plane that becomes the front of the speaker unit 111 (see Figure 52 ).

[0193] In addition, the plane that becomes the front of the speaker unit 111, the plane that becomes the front of the collar 112, and the plane that becomes the front of the annular collar 714 are preferably substantially parallel as shown in Figure 49 . Figure 49 Among them, the plane that becomes the front of the speaker unit 111 is substantially the same as the plane that becomes the front of the collar 112.

[0194] The collar 112 is a housing that causes the sound played from the speaker unit 111 in the back direction of the speaker unit 111, that is, the out-of-phase sound, to bypass to the front direction of the speaker unit 111. In the collar 112, there are holes (hereinafter referred to as the first out-of-phase sound playback holes) for playing the bypassed out-of-phase sound to the front direction of the speaker unit 111.

[0195] The collar 112 houses a part of the speaker unit 111 in such a form that the path from the hole of the speaker unit 111 for playing the out-of-phase sound to the first out-of-phase sound playback hole is shortened, and the frequency (hereinafter referred to as the resonance frequency) caused by the resonance of the internal space of the collar 112 generated between the collar 112 and the speaker unit 111 becomes higher, so that in a specified frequency band in the front direction of the speaker unit 111, the out-of-phase sound played from the first out-of-phase sound playback hole to the front direction of the speaker unit 111 and the in-phase sound played from the speaker unit 111 to the front direction of the speaker unit 111 are in a substantially out-of-phase relationship. In addition, the specified frequency band is preferably a frequency band below the resonance frequency of the internal space of the collar 112 generated between the collar 112 and the speaker unit 111. When the path from the hole of the speaker unit 111 for playing the out-of-phase sound to the first out-of-phase sound playback hole becomes short, as long as the speaker unit 111 is a speaker unit for a dynamic speaker, the magnet part constituting the speaker unit 111 does not need to be housed in the collar 112. In addition, when the resonance frequency of the internal space of the collar 112 generated between the collar 112 and the speaker unit 111 becomes higher, considering the formula (1) related to the resonance frequency f H related to Helmholtz resonance, one or more of the three methods of increasing the area S of the first out-of-phase sound playback hole, reducing the volume V of the internal space, and shortening the length L of the first out-of-phase sound playback hole are used to adjust the resonance frequency, and it is sufficient for the collar 112 to house a part of the speaker unit 111.

[0196] Similar to the first embodiment, it is also possible to adjust the position of the sweet spot in the front direction of the speaker unit by installing a component (hereinafter referred to as a baffle) that adjusts the position for canceling the out-of-phase sound and the in-phase sound in the low-frequency region to a position away from the speaker unit. That is, it is also possible to install a baffle 113, which is a component that prevents the out-of-phase sound played from the first out-of-phase sound playback hole and the in-phase sound played from the speaker unit 111 from canceling each other out at the position of the sweet spot in the front direction of the speaker unit 111, on the speaker unit 111.

[0197] According to an embodiment of the present invention, it is possible to increase the sweet spot in a limited area near the speaker unit. By using an annular collar, it is possible to suppress sound leakage in the high-frequency region. In addition, it is possible to suppress sound leakage in the back direction.

[0198] <Remarks>

[0199] The description of the above embodiment of the present invention is presented for the purpose of illustrative recording. It has no inclusive meaning and no intention of limiting the invention to the strict form disclosed. Modifications and variations can be achieved according to the above teachings. The embodiment is selected and presented to provide the best illustration of the principles of the present invention and to enable those skilled in the art to utilize the present invention in various embodiments, with various modifications added, in a manner suitable for the well-known actual use. All such modifications and variations are within the scope of the present invention determined by the appended claims interpreted within the fairly and legally fair scope.

Claims

1. An acoustic signal output device, comprising: a speaker unit; a collar, which is a housing that houses a part of the speaker unit in order to direct the sound (hereinafter referred to as the out-of-phase sound) played from the speaker unit in the back direction of the speaker unit around to the front direction of the speaker unit; an annular collar, which is an annular member having a size capable of covering the periphery of the side direction of the collar; a hole (hereinafter referred to as the first out-of-phase sound playback hole) for playing the out-of-phase sound in the front direction of the speaker unit is provided in the collar, the collar houses a part of the speaker unit in such a form that the path from the hole of the speaker unit for playing the out-of-phase sound to the first out-of-phase sound playback hole is shortened, and the resonance frequency of the internal space of the collar generated between the collar and the speaker unit becomes higher, so that in a specified frequency band in the front direction of the speaker unit, the out-of-phase sound played from the first out-of-phase sound playback hole and the sound (hereinafter referred to as the in-phase sound) played from the speaker unit in the front direction of the speaker unit are in a substantially out-of-phase relationship.

2. The acoustic signal output device according to claim 1, a baffle is installed between the collar and the annular collar, and the baffle is a component for suppressing the leakage of sound in the back direction of the speaker unit.

3. The acoustic signal output device according to claim 1, the annular collar has an illumination function.

4. The acoustic signal output device according to claim 1, one or more of the three methods of increasing the area of the first out-of-phase sound playback hole, reducing the volume of the internal space, and shortening the length of the first out-of-phase sound playback hole are used to increase the resonance frequency of the internal space.

5. The acoustic signal output device according to claim 1, a baffle is installed on the speaker unit, and the baffle is a component for preventing the out-of-phase sound played from the first out-of-phase sound playback hole and the in-phase sound from canceling each other out at the position that wants to be the sweet spot in the front direction of the speaker unit.

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