Speaker system and acoustic system

Abstract

To provide a speaker system and an acoustic system with which it is possible to build a compact sound field in the vicinity of the user's head.SOLUTION: A speaker system 1 according to the present disclosure comprises: a right speaker 11 for emitting a sound for the right ear based on an acoustic signal; a left speaker 12 for emitting a sound for the left ear based on an acoustic signal; and a center speaker 13 located between the right speaker 11 and the left speaker 12, for emitting a sound for the right ear and a sound for the left ear based on these acoustic signals. In this case, the center speaker 13 is located so that its sound emission direction is directed opposite the sound emission directions of the right speaker 11 and the left speaker 12. An acoustic system according to the present disclosure includes an amplifier for outputting, in addition to the speaker system 1, a stereo acoustic signal for the right ear and a stereo acoustic signal for the left ear to the right speaker 11, the left speaker 12, and the center speaker 13 of the speaker system 1, respectively.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a speaker system and an acoustic system including three speakers.

Background Art

[0002] There is known an acoustic system that constructs a sound field only in the vicinity of a user's head without using earphones or headphones (see, for example, Patent Document 1). In the acoustic system described in Patent Document 1, a plurality of speaker pairs are provided, each speaker pair including a speaker that emits sound based on an acoustic signal of a predetermined sound source and a speaker that emits sound based on an acoustic signal having a phase opposite to that of the acoustic signal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the acoustic system described in Patent Document 1, when listening to sounds such as music based on a stereo acoustic signal including a signal for the right ear and a signal for the left ear, at least four speakers (two speaker pairs) are required. And in order to construct a sound field in the vicinity of the user's head, for example, either a first method of arranging this acoustic system in a headrest (that is, arranging four speakers in the same plane) or a second method of arranging it on both side surfaces or the rear surface near the user's head is adopted.

[0005] However, in either method, there is a problem that the size of the entire acoustic system becomes large, and it cannot fit in the headrest or may obstruct the user's view.

[0006] The object of the present disclosure is to solve such problems, and the object is to configure with three speakers and arrange the sound emission direction (the front direction of the diaphragm) of the speaker arranged in the center in the opposite direction to the other two, so that while ensuring the size of the speaker diameter, the size of the entire system can be suppressed, and a compact sound field with stable sound quality can be realized. To provide a speaker system and an acoustic system.

Means for Solving the Problems

[0007] The speaker system according to the present disclosure is a right speaker that emits sound for the right ear based on an acoustic signal, a left speaker that emits sound for the left ear based on the acoustic signal, a center speaker disposed between the right speaker and the left speaker, and emitting the sound for the right ear and the sound for the left ear based on the acoustic signal, comprising the right speaker, the left speaker, and the center speaker are each attached to a planar baffle, The center speaker is arranged such that its sound emission direction is opposite to the sound emission directions of the right speaker and the left speaker.

[0008] The acoustic system according to the present disclosure is the speaker system as described above, an amplifier that outputs a stereo acoustic signal for the right ear and a stereo acoustic signal for the left ear, comprising the right speaker, the left speaker, and the center speaker of the speaker system each have a plus terminal and a minus terminal to which the stereo acoustic signal is input from the amplifier, The amplifier has a plus terminal and a minus terminal for each of the stereo acoustic signal for the right ear and the stereo acoustic signal for the left ear corresponding to the right speaker, the left speaker, and the center speaker, The right speaker, the left speaker, and the center speaker, and the amplifier are connected such that the positive terminal for the right ear of the amplifier is connected to the positive terminal of the right speaker, the positive terminal for the left ear of the amplifier is connected to the positive terminal of the left speaker, and the negative terminal for the right ear of the amplifier is connected to the negative terminal of the center speaker, and the positive terminal of the center speaker is connected to the negative terminals of the right speaker and the left speaker, which is an audio system.

Effect of the Invention

[0009] According to the speaker system and the audio system according to the present disclosure, by configuring with three speakers and arranging the sound emission direction of the speaker arranged in the center in the opposite direction to the other two, it is possible to suppress the size of the entire system while securing the size of the speaker diameter. Further, with such a configuration, it is possible to realize a compact sound field with stable sound quality.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the invention according to the claims is not limited to the following embodiments. Also, not all of the configurations described in this embodiment are necessarily essential as means for solving the problems. For the sake of clarity of explanation, the following description and drawings have been appropriately omitted and simplified. In each drawing, the same elements are denoted by the same reference numerals, and duplicate explanations are omitted as necessary.

[0012] <Background Leading to the Present Disclosure> As described above, in the acoustic system described in Patent Document 1, at least four speakers (two speaker pairs) are required. And in order to construct a sound field near the user's head, either the first plan of arranging the acoustic system inside the headrest or the second plan of arranging it on both side surfaces or the rear back surface near the user's head is adopted.

[0013] Here, the acoustic system described in Patent Document 1 utilizes the characteristic that the sound field of one speaker does not spread by emitting, from the other speaker, a sound based on an acoustic signal having a phase opposite to that of the acoustic signal for one speaker. However, such a characteristic is more effectively exhibited for sounds with low frequencies (bass) where sound wraps around, and it is difficult to exhibit such a canceling effect for sounds with high frequencies (treble).

[0014] As described above, when using at least four speakers, in the first plan, the headrest becomes large beyond the width of the seat or chair (e.g., gaming chair), or the acoustic system is configured with small-diameter speakers for which the effect in the bass range is difficult to exhibit. In order to reproduce low-frequency sounds with small-diameter speakers, it is necessary to vibrate the speaker diaphragm with a large amplitude, but such a configuration causes deterioration of sound quality such as an increase in distortion, and thus is not preferable in practical terms.

[0015] On the other hand, in the second plan, two speakers are respectively arranged on both sides near the user's head, and the user's field of vision is impaired. In particular, when driving a vehicle such as an automobile, it is difficult to adopt this second plan due to safety issues.

[0016] Furthermore, it is difficult to fix the position of the user's head during use of the acoustic system. By arranging, close to the user's left and right ears respectively, a speaker that outputs a sound based on a positive-phase acoustic signal and a speaker that outputs a sound based on a negative-phase acoustic signal, a situation easily occurs where the distance between the right speaker and the user's right ear and the distance between the left speaker and the user's left ear are different on the left and right, and the balance of the sound pressure on the left and right easily collapses. Since the sound pressure difference between the left and right is felt by humans more sensitively than sound quality, it is preferable to achieve the same volume feeling as much as possible. Thus, neither the first plan nor the second plan can be said to be preferable.

[0017] In view of such problems, the inventor of the present application came up with the idea of constructing a speaker system using three speakers and devising the wiring between this speaker system and an amplifier to construct an acoustic system that can also be configured with an existing amplifier. Hereinafter, the speaker system and the acoustic system according to the present disclosure will be described.

[0018] (Embodiment 1) <Speaker System> First, the configuration of the speaker system 1 according to Embodiment 1 will be described. FIG. 1 is a front view showing the overall configuration of the speaker system 1 according to Embodiment 1. FIG. 2 is a top view showing an example of the arrangement of the speaker system 1 according to Embodiment 1. In FIG. 2, the upper surface portion of the enclosure is omitted, and the user's head A is shown so that the positional relationship between the user of the speaker system 1 and the speaker system 1 can be understood.

[0019] As shown in FIGS. 1 and 2, the speaker system 1 according to Embodiment 1 includes a right speaker 11, a left speaker 12, and a center speaker 13. In this example, these speakers 11, 12, and 13 are provided inside the headrest 2. Note that the headrest 2 is installed behind the head of a user when sitting on a seat of a vehicle such as an automobile, a sofa, or a chair such as a gaming chair, either integrally with one of these or as a separate member.

[0020] The right speaker 11 is configured to emit sound for the right ear based on an acoustic signal input from an amplifier of an acoustic system described later. The left speaker 12 is configured to emit sound for the left ear based on an acoustic signal input from an amplifier of the acoustic system. The center speaker 13 is configured to emit sound for the right ear and sound for the left ear based on an acoustic signal input from an amplifier of the acoustic system. Further, as shown in FIG. 2, the center speaker 13 is arranged between the right speaker 11 and the left speaker 12 such that its sound emission direction is opposite to the sound emission directions of the right speaker 11 and the left speaker 12. Note that the sound emission direction is the direction in which the front of each of the speakers 11, 12, and 13 faces.

[0021] By configuring the speaker system 1 in this way, the sound output in the +X direction, which is the sound emission direction of the right speaker 11 and the left speaker 12, from in front of the diaphragm 111 of the right speaker 11 and in front of the diaphragm 121 of the left speaker 12, and the sound output in the +X direction from behind the diaphragm 131 of the center speaker 13 are sounds with opposite phases to each other. In other words, a sound with a phase opposite to that of the sound output from the right speaker 11 and the left speaker 12 is output from the center speaker 13 in the same +X direction. For this reason, sound cancellation occurs in the +X direction and the sound is canceled. Similarly, the sound output in the -X direction, which is the direction opposite to the sound emission direction, from behind the diaphragm 111 of the right speaker 11 and behind the diaphragm 121 of the left speaker 12, and the sound output in the -X direction from in front of the diaphragm 131 of the center speaker 13 are sounds with opposite phases to each other. For this reason, sound cancellation also occurs in the -X direction and the sound is canceled. The effect of generating a compact sound field due to such sound cancellation will be described later.

[0022] The right speaker 11 includes a diaphragm 111, a magnetic circuit section 112, and a planar baffle 113. The left speaker 12 includes a diaphragm 121, a magnetic circuit section 122, and a planar baffle 123. The center speaker 13 includes a diaphragm 131, a magnetic circuit section 132, and a planar baffle 133. Each of the speakers 11, 12, 13 converts an acoustic signal (electrical signal) from an amplifier (not shown) into physical sound (vibration of air) by means of the diaphragms 111, 121, 131 and the magnetic circuit sections 112, 122, 132. Also, the planar baffles 113, 123, 133 prevent the bass sound emitted from the rear surface side in the sound emission direction of each of the speakers 11, 12, 13 from diffracting to the front surface side.

[0023] As shown in FIG. 2, the diaphragm 131 of the center speaker 13 is offset from the diaphragms 111 of the right speaker 11 and 121 of the left speaker 12 in the depth direction of the headrest 2, which is the +X direction, the sound emission direction of the right speaker 11 and the left speaker 12, that is, it is arranged at a position that is not on the same plane. With such an arrangement, compared to the case where all the diaphragms 111, 121, and 131 are arranged on the same plane, the diaphragms 111, 121, and 131 do not interfere with each other. Therefore, while suppressing the size of the speaker system 1, the speaker diameters of the respective speakers 11, 12, and 13 can be increased. As a result, each speaker 11, 12, and 13 can output low-frequency sounds without unduly increasing the vibration (amplitude) of each diaphragm 111, 121, and 131, and it is possible to achieve both the compactness of the speaker system 1 and the adoption of large-diameter speaker diaphragms suitable for low frequencies. Here, in this example, the low frequency refers to a sound with a frequency of 500 Hz or less.

[0024] Also, as shown in FIG. 2, the diaphragm 111 of the right speaker 11 is arranged such that the central position in its lateral width direction is near the rear of the right ear of the user of the speaker system 1, and the diaphragm 121 of the left speaker 12 is arranged such that the central position in its lateral width direction is near the rear of the left ear of the user. Thereby, the sound of positive phase (positive phase) emitted from the right speaker 11 and the left speaker 12 can reach the user at a short distance. Further, since the center speaker 13 that outputs the sound of reverse phase in the sound emission direction (+X direction) is far from the user's ear, the sound of reverse phase is less likely to be heard by the user. In this way, at the user's ear, there is a distance difference between the right speaker 11 and the left speaker 12 and the center speaker 13, so the sounds emitted from the respective speakers 11, 12, and 13 are not canceled out. Also, the balance of the sound pressure of the left and right sounds heard by the user is less likely to be disrupted.

[0025] In addition, since the user's head A may move in the direction perpendicular (lateral direction) to the +X direction in FIG. 2, within the range allowed as the size of the headrest 2, the distance between the right speaker 11 and the left speaker 12 may be slightly widened.

[0026] Here, as shown in FIG. 2, the lateral width W of the user's head A is, for example, about 15 to 16 cm, which is the average lateral width (face width) of a Japanese person's face. Therefore, in the first case where four speakers for the left and right ears are arranged in the same plane on the back head side of the user and emit sounds of positive and reverse phases respectively, as in the acoustic system of Patent Document 1, the maximum speaker diameter is limited to about 8 cm.

[0027] Also, in the second case where the acoustic system of Patent Document 1 is arranged on both side surfaces and obliquely rearward in the vicinity of the user's head A, there is a problem that the user's field of view is impaired. In particular, when driving a vehicle such as an automobile, such an acoustic system becomes a problem of safety in vehicle driving.

[0028] In the acoustic system of Patent Document 1, a method of arranging two speakers for the right ear that emit sounds of positive and reverse phases and two speakers for the left ear that emit sounds of positive and reverse phases side by side in the vertical direction can also be considered. However, there is a problem that the entire acoustic system becomes large because the headrest 2 becomes large not only in the horizontal direction but also in the vertical direction.

[0029] By the way, each of the speakers 11, 12, and 13 in this example, which are normal speakers, has a feature that the diameter D1 of the diaphragms 111, 121, and 131 is larger than the outer diameter D2 of the magnetic circuit parts 112, 122, and 132.

[0030] Therefore, in the speaker system 1 of the present embodiment, as shown in FIG. 2, the right speaker 11 and the left speaker 12 are arranged so as to face the +X direction, and the center speaker 13 is arranged between the right speaker 11 and the left speaker 12 so as to face the -X direction. With such an arrangement, the entire speaker system 1 can be compactly housed in the headrest 2, and the diameter D1 of each diaphragm 111, 121, 131 can be increased to about 16 cm at most. Thereby, compared with the acoustic system of Patent Document 1, while adopting a large-diameter speaker diaphragm suitable for bass, it is possible to realize the compactness of the entire speaker system 1 and the compact sound field due to the above-described sound cancellation.

[0031] A gap (space) is provided in the headrest 2 so that the back of the user's head does not press against the magnetic circuit portion 132 of the center speaker 13 even when the user's head A of the speaker system 1 leans against the headrest 2. Further, in the headrest 2, a cushion material 40 for relaxing the contact pressure with the user's head A is provided in front in the +X direction. It should be noted that it is also possible to omit the cushion material 40 in consideration of the comfort of the user (such as the repulsive force on the head).

[0032] <Acoustic system> Next, the acoustic system according to Embodiment 1 will be described. FIG. 3 is a conceptual diagram showing an example of the wiring configuration of the acoustic system 100 according to Embodiment 1. As shown in FIG. 3, the acoustic system 100 includes the speaker system 1 according to the present embodiment, an amplifier 3 that outputs an acoustic signal to the speaker system 1, and a plurality of wiring cords 301 to 305 that connect the speaker system 1 and the amplifier 3.

[0033] The amplifier 3 is configured to output a stereo audio signal for the right ear and a stereo audio signal for the left ear to each of the speakers 11, 12, and 13 of the speaker system 1. That is, the amplifier 3 includes four amplifier terminals, namely, a plus terminal 31 and a minus terminal 32 for the right ear (R side), and a plus terminal 33 and a minus terminal 34 for the left ear, for connection to each of the speakers 11, 12, and 13 of the speaker system 1.

[0034] On the other hand, although not shown in FIGS. 1 and 2, the right speaker 11 further has a plus terminal 114 and a minus terminal 115 on the back surface of the magnetic circuit unit 112, the left speaker 12 further has a plus terminal 124 and a minus terminal 125 on the back surface of the magnetic circuit unit 122, and the center speaker 13 further has a plus terminal 134 and a minus terminal 135 on the back surface of the magnetic circuit unit 122.

[0035] Thus, the amplifier 3 has four terminals 31 to 34 for outputting stereo audio signals to the two left and right speakers 11 and 12, while the speaker system 1 has a total of six terminals 114, 115, 124, 125, 134, and 135 for all the speakers 11, 12, and 13. Therefore, special wiring is required to connect the amplifier 3 and the speaker system 1. In the audio system 100 according to the present embodiment, wiring as shown in FIG. 3 is made between the three speakers 11, 12, and 13 and the amplifier 3. Such wiring is called matrix wiring, and in particular, the wiring in FIG. 3 is called a semi-matrix method. By using such wiring, an existing amplifier 3 can be effectively utilized, and the sound field created by the speaker system 1 has a unique surround feeling.

[0036] Specifically, as shown in FIG. 3, the plus terminal 31 for the right ear of the amplifier 3 is connected to the plus terminal 114 of the right speaker 11 via the wiring cord 301, and the plus terminal 33 for the left ear of the amplifier 3 is connected to the plus terminal 124 of the left speaker 12 via the wiring cord 302. Also, the minus terminal 32 for the right ear of the amplifier 3 is connected to the minus terminal 135 of the center speaker 13 via the wiring cord 303, but the minus terminal 34 for the left ear of the amplifier 3 is not connected to any terminal.

[0037] And within the speaker system 1, the plus terminal 134 of the center speaker 13 is connected to the minus terminal 115 of the right speaker 11 via the wiring cord 304 and is also connected to the minus terminal 125 of the left speaker 12 via the wiring cord 305.

[0038] The wiring pattern from the amplifier 3 described above is an example of an embodiment of the acoustic system 100 according to the present embodiment. Alternatively, the acoustic system 100 according to the present embodiment may be configured such that the amplifier 3 further has two terminals in addition to the four terminals 31 to 34. In this case, the four terminals 31 to 34 for outputting the stereo audio signal from the amplifier 3 to the left and right speakers 11 and 12 are respectively connected to the four terminals 114, 115, 124, and 125 of the left and right speakers 11 and 12, and the additional two terminals (not shown) for outputting the stereo audio signal from the amplifier 3 to the center speaker 13 may be respectively connected to the two terminals 134 and 135 of the center speaker 13. Also, the two terminals for outputting the stereo audio signal to the center speaker 13 may be provided in an audio device (not shown) for synthesizing the output from the amplifier 3.

[0039] <Sound field> Next, the sound field constructed by each of the speakers 11, 12, and 13 will be described. FIG. 4 is a conceptual diagram showing an image of the sound field constructed by each of the speakers 11, 12, and 13 that constitute the speaker system 1 according to the first embodiment. Here, the right speaker 11 and the left speaker 12 are configured to emit sound based on an acoustic signal in the +X direction and emit sound of the opposite phase of the sound based on the same acoustic signal in the -X direction. Further, the center speaker 13 is installed facing the opposite direction to the right speaker 11 and the left speaker 12, so that it emits sound based on the same acoustic signal in the -X direction and emits sound of the opposite phase of the sound based on the same acoustic signal in the +X direction.

[0040] As shown in FIG. 4(a), for example, the sound field S1 due to the sound of the positive phase emitted from the front of the right speaker 11 and the sound field S2 due to the sound of the opposite phase emitted from the rear of the right speaker 11 spread forward and backward respectively centering on the speaker. Then, in the lateral direction of the speaker, the sound of the positive phase spreading forward and the sound of the opposite phase spreading backward cancel each other out, so the sound field does not spread. Also, as the distance from the center of each sound field S1, S2 increases, the sound pressure decreases.

[0041] Next, as shown in FIG. 4(b), for example, when the right speaker 11 and the left speaker 12 are arranged side by side, the sound pressures strengthen each other in front of and behind both speakers 11, 12, so larger sound fields S11 (positive phase), S12 (opposite phase) are constructed than in the case shown in FIG. 4(a). For comparison, the sound fields S1, S2 constructed when each of the speakers 11, 12 is a single unit are shown by dotted lines.

[0042] Finally, as shown in FIG. 4(c), when the center speaker 13 is arranged in the opposite direction between the right speaker 11 and the left speaker 12, since the center speaker 13 provides a canceling effect on the enlarged sound field shown in FIG. 4(b), smaller sound fields S21 (positive phase), S22 (opposite phase) are constructed than in the case shown in FIG. 4(b). Thus, according to the arrangement of the speaker system 1, a compact sound field centered around the vicinity of the user's head A can be constructed.

[0043] Hereinafter, the sound field based on the arrangement of the speakers will be described with reference to Examples and Comparative Examples.

[0044] (Example) First, the sound field constructed by the speaker system 1 according to the present embodiment will be described. FIG. 5 is a diagram showing the arrangement in the sound field analysis of the speaker system according to the example. FIG. 6 is a diagram showing the result of the sound field analysis of the speaker system according to the example. In the present example, the speaker system 1 is configured as an open speaker in which each speaker is attached to a planar baffle.

[0045] As shown in FIG. 5(b), the speaker system 1 of the present example includes a right speaker 11, a left speaker 12, and a center speaker 13. As described above, the right speaker 11 and the left speaker 12 are arranged so as to face in the +X direction toward the user's head A, and the center speaker 13 is arranged so as to face in the opposite -X direction.

[0046] At this time, as shown in FIG. 5(a), the sound pressure observation surface SP is arranged in a grid pattern centered on each of the speakers 11, 12, and 13. As described in the construction of the sound field of the present embodiment, at a position equidistant from the right speaker 11 and the center speaker 13, the sound output from the front of the right speaker 11 in the +X direction and the sound output from the rear of the center speaker 13 in the +X direction are out of phase with each other. Therefore, the vibrations of the sounds interfere with each other and cancel each other out, and the sound is canceled. Similarly, the sound output from the rear of the right speaker 11 in the -X direction and the sound output from the front of the center speaker 13 in the -X direction also cause cancellation of the sounds, and the sound is canceled.

[0047] On one hand, in the vicinity of the user's head A, which is relatively close to the right speaker 11 and the center speaker 13, since the difference in distance from the right speaker 11 and the center speaker 13 is large, the above-described sound cancellation does not occur and the sound is not canceled. Therefore, in the speaker system 1 of the present embodiment, a compact sound field can be constructed such that a sound field is constructed in the vicinity of the user's head A, but not in other places. Similarly, in the relationship between the left speaker 12 and the center speaker 13, a compact sound field can be constructed as well.

[0048] As a result, the sound field constructed by the speaker system 1 according to the present embodiment is a compact sound field in which sufficient sound pressure is ensured in a range where the distances from the speakers 11, 12, and 13 are close, and the sound pressure gain rapidly decreases as the distances from the speakers 11, 12, and 13 increase, as shown in FIG. 6. Here, the range indicated by the gain G1 is the sound pressure range of the gain of 0 dB or more. The range indicated by the gain G2 is the sound pressure range of the gain of -9 to 0 dB, and the range indicated by the gain G3 is the sound pressure range of the gain of -18 to -9 dB. The range of the gain G4 less than -18 dB is a range where the sound emitted from each of the speakers 11, 12, and 13 is hardly or not heard at all.

[0049] As can be seen from the results of the sound field analysis shown in FIG. 6, according to the speaker system 1 of the present embodiment, while ensuring the size of the speaker diameter, the size of the entire speaker system 1 can be suppressed, and a compact sound field can be realized in the vicinity of the speaker system 1. In particular, since the sound pressure (sound) of the gain G1 with the highest gain reaches the vicinity of the user's left and right ears, the user of the speaker system 1 can hear a sound with stable sound quality. On the other hand, since the sound field is compact, other users near the same room or the like will not feel uncomfortable due to the leaking sound.

[0050] (Comparative Example 1) Next, the sound field constructed by the speaker system according to Comparative Example 1 will be described. FIG. 7 is a diagram showing the arrangement in the sound field analysis of the speaker system according to Comparative Example 1. FIG. 8 is a diagram showing the result of the sound field analysis of the speaker system according to Comparative Example 1. In Comparative Example 1, the speaker system is configured as a sealed speaker.

[0051] As shown in FIG. 7(b), the speaker system of Comparative Example 1 includes a right speaker 11 and a left speaker 12. In this Comparative Example 1, the right speaker 11 and the left speaker 12 are arranged to emit sound with a positive phase in the +X direction toward the user's head A. That is, in Comparative Example 1, no speaker that emits sound with a reverse phase in the +X direction is arranged.

[0052] At this time, as shown in FIG. 7(a), the sound pressure observation surface SP is arranged in a grid pattern centered on each of the speakers 11 and 12. Also in Comparative Example 1, as in the above-described embodiment, as the distance from each of the speakers 11 and 12 increases, the sound pressure gain decreases.

[0053] As a result, as shown in FIG. 8, the sound field constructed by the speaker system according to Comparative Example 1 spreads over a considerably wider range compared to the embodiment. Note that the gains G1 to G4 are the same as in the above-described embodiment.

[0054] As can be seen from the result of the sound field analysis shown in FIG. 8, according to the speaker system of Comparative Example 1, similar to the embodiment, the sound pressure (sound) of the gain G1 with the highest gain reaches near the user's left and right ears. However, the sound pressure of the gain G2 and the sound pressure of the gain G3 spread widely in a substantially concentric circle shape without the sounds canceling each other out. Thus, in the speaker system of Comparative Example 1, other users near the same room or the like may feel uncomfortable due to the leaking sound.

[0055] (Comparative Example 2) Finally, the sound field constructed by the speaker system according to Comparative Example 2 will be described. FIG. 9 is a diagram showing the arrangement in the sound field analysis of the speaker system according to Comparative Example 2. FIG. 10 is a diagram showing the result of the sound field analysis of the speaker system according to Comparative Example 2. In Comparative Example 2, the speaker system is configured as an open speaker.

[0056] As shown in FIG. 9(b), the speaker system of Comparative Example 2 includes a first right speaker 11 that emits a sound in the positive phase, a second right speaker 14 that emits a sound in the reverse phase, a first left speaker 12 that emits a sound in the positive phase, and a second left speaker 15 that emits a sound in the reverse phase. This configuration corresponds to the second proposal for the acoustic system described in Patent Document 1. That is, the first right speaker 11 and the second right speaker 14 are arranged to emit sound in the +Y direction toward the right ear at the user's head A, and the first left speaker 12 and the second left speaker 15 are arranged to emit sound in the opposite -Y direction.

[0057] At this time, as shown in FIG. 9(a), the sound pressure observation surface SP is arranged in a grid pattern centered on each of the speakers 11, 12, 14, and 15. Similar to the embodiment, as the distance from each of the speakers 11, 12, 14, and 15 increases, the sound pressure gain decreases. At positions where the distances from the first right speaker 11 and the second right speaker 14 are the same, or where the distances from the first left speaker 12 and the second left speaker 15 are the same, the sounds cancel each other out, and the sound pressure gain becomes so small that it cannot be measured.

[0058] As a result, in the sound field constructed by the speaker system according to Comparative Example 2, as shown in FIG. 10, the sound pressure gain decreases as the distance from the speakers 11, 12, 14, and 15 increases. The gains G1 to G4 are the same as those in the above embodiment.

[0059] As can be seen from the results of the sound field analysis shown in FIG. 10, according to the speaker system of Comparative Example 2, similar to the embodiment, it is possible to realize a more compact sound field with stable sound quality. However, two speakers must be installed on each of the two side surfaces of the user's head A. As described in the second solution above, the user's field of vision will be impaired and there are also problems with the installation method. Since the sound field is compact, other users near the same room or the like will not feel uncomfortable due to the leaking sound. However, when driving a vehicle such as an automobile, a safety problem will occur. Also, as a result, since it is necessary to arrange the two speaker pairs 11 and 14, 12 and 15 so as to emit sound in the same direction, there is also a problem that the entire speaker system becomes larger compared to the speaker system 1 of the embodiment composed of three speakers.

[0060] As described above, the speaker system 1 according to the present embodiment includes a right speaker 11 that emits sound for the right ear based on an acoustic signal, a left speaker 12 that emits sound for the left ear based on the acoustic signal, and is disposed between the right speaker 11 and the left speaker 12, and is configured to include a center speaker 13 that emits sound for the right ear and sound for the left ear based on these acoustic signals. The right speaker 11, the left speaker 12, and the center speaker 13 are respectively attached to the planar baffles 113, 123, and 133, and the center speaker 13 is configured to be disposed such that its sound emission direction is opposite to the sound emission directions of the right speaker 11 and the left speaker 12. Usually, in each of the speakers 11, 12, and 13, the diameter D1 of the diaphragm 111, 121, 131 is larger than the outer diameter D2 of the magnetic circuit portions 112, 122, 132. Therefore, by arranging the speakers 11, 12, and 13 such that their sound emission directions are staggered, the size of the entire speaker system 1 can be suppressed, and the speaker diameters of the speakers 11, 12, and 13 can be increased. Thereby, the spread of low-frequency sound can be suppressed, and a compact sound field with stable sound quality can be realized.

[0061] Also, in the speaker system 1 according to the present embodiment, the diaphragm 111 of the right speaker 11 is arranged such that the central position in the lateral width direction thereof is near the rear of the right ear of the user of the speaker system 1, and the diaphragm 121 of the left speaker 12 is arranged such that the central position in the lateral width direction thereof is near the rear of the left ear of the user. With such a configuration, the sound pressure (sound) of the highest gain G1 reaches near the left and right ears of the user of the speaker system 1, so that the user of the speaker system 1 can listen to sound with stable sound quality. On the other hand, since the sound field is compact, other users near the same room or the like do not feel discomfort due to the sound that leaks and can be heard.

[0062] In addition, the audio system 100 according to the present embodiment is configured to include the speaker system 1 as described above, an amplifier 3 that outputs a stereo audio signal for the right ear and a stereo audio signal for the left ear. The right speaker 11, the left speaker 12, and the center speaker 13 of the speaker system 1 each have a plus terminal 114, 124, 134 and a minus terminal 115, 125, 135 to which a stereo audio signal is input from the amplifier 3. The amplifier 3 also has plus terminals 31, 33 and minus terminals 32, 34 for each of the stereo audio signal for the right ear and the stereo audio signal for the left ear corresponding to the right speaker 11, the left speaker 12, and the center speaker 13. Further, the right speaker 11, the left speaker 12, and the center speaker 13 and the amplifier 3 are configured such that the plus terminal 31 for the right ear of the amplifier 3 is connected to the plus terminal 114 of the right speaker 11, the plus terminal 33 for the left ear of the amplifier 3 is connected to the plus terminal 124 of the left speaker 12, the minus terminal 32 for the right ear of the amplifier 3 is connected to the minus terminal 135 of the center speaker 13, and the plus terminal 134 of the center speaker 13 is connected to the minus terminal 115 of the right speaker 11 and the minus terminal 125 of the left speaker 12. By configuring the audio system 100 in this way, the effects of the speaker system 1 described above can be maximally exerted. Also, by connecting the speaker system 1 and the amplifier 3 in this way, an existing amplifier 3 can be effectively utilized, and the sound field created by the speaker system 1 has a unique surround feeling.

[0063] (Embodiment 2) Hereinafter, with reference to FIGS. 11 to 13, a speaker system according to Embodiment 2 will be described. Note that FIGS. 11 and 12 are obtained by adding a contact sensor 50 and a position changing mechanism 60 to FIGS. 1 and 2 of Embodiment 1, as will be described later. Therefore, descriptions of overlapping components in the speaker system 1A according to Embodiment 2 will be omitted.

[0064] <Speaker system> First, the configuration of the speaker system 1A according to Embodiment 2 will be described. FIG. 11 is a front view showing the overall configuration of the speaker system 1A according to Embodiment 2. FIG. 12 is a top view showing an example of the arrangement of the speaker system 1 according to Embodiment 2. FIG. 13 is a block diagram showing an example of the speaker position changing method in the speaker system 1A shown in FIG. 11. In each part of the speaker system 1A, the same or similar components as those of the speaker system 1 in Embodiment 1 are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0065] As shown in FIGS. 11 to 13, the speaker system 1A further includes a contact sensor 50, a position changing mechanism 60, and a control unit 70 with respect to the speaker system 1 of Embodiment 1. Although not shown, the control unit 70 is provided inside the headrest 2. However, when the control unit 70 can communicate via a wireless communication unit (not shown), it may be provided at another location. Also, when the speaker system 1A is arranged inside the headrest 2 of the vehicle, the control unit 70 may be substituted by the vehicle's ECU (Electronic Control Unit).

[0066] The contact sensor 50 is configured to detect the contact between the headrest 2 and the user's head A. The contact sensor 50 may be a switch-type tactile switch or a pressure sensor that detects the contact pressure. When the contact sensor 50 detects the contact of the user's head A, it outputs a detection result (detection information) indicating the contact detection to the control unit 70.

[0067] The control unit 70 controls the entire speaker system 1A and is composed of a processor or a CPU (Central Processing Unit). When the control unit 70 receives the detection information of the contact sensor 50, it controls the position changing mechanism 60 to change the position of the center speaker 13 in the X direction.

[0068] The position changing mechanism 60 is configured to move the center speaker 13 by a predetermined distance in the -X direction in response to an instruction from the control unit 70. The position changing mechanism 60 is constituted by, for example, an electric actuator. Here, the predetermined distance is a distance at which no sound cancellation occurs near the user's ear due to the sound of the positive phase emitted from the right speaker 11 and the left speaker 12 in the +X direction and the sound of the reverse phase emitted from the center speaker 13 in the +X direction. When the contact between the headrest 2 and the user's head A is detected, since the difference between the distance from the right speaker 11 and the left speaker 12 to the user's ear and the distance from the center speaker 13 to the user's ear becomes relatively large, it is preferable to arrange the center speaker 13 away from the right speaker 11 and the left speaker 12. For this reason, the center speaker 13 is moved in the -X direction by the position changing mechanism 60.

[0069] Here, when the contact sensor 50 is constituted by a pressure sensor, the position changing mechanism 60 may move the position of the center speaker 13 stepwise in accordance with the control of the control unit 70. For example, let P1 and P2 (P1 < P2) be set in the control unit 70 as the threshold values of the pressure sensor. In this case, when the detection result received from the contact sensor 50 is equal to or greater than P1 and less than P2, the control unit 70 controls the position changing mechanism 60 to move the center speaker 13 by half of the predetermined distance in the -X direction. Further, when the detection result received from the contact sensor 50 is equal to or greater than P2, the control unit 70 controls the position changing mechanism 60 to move the center speaker 13 by the predetermined distance in the -X direction.

[0070] Note that instead of the contact sensor 50, a distance measuring sensor (not shown) may be provided. Then, the control unit 70 may control the movement of the center speaker 13 by the position changing mechanism 60 based on the distance between the headrest 2 and the user's head A, which is the detection result of the distance measuring sensor.

[0071] As described above, in addition to each part included in the speaker system 1 according to the first embodiment, the speaker system 1A according to the present embodiment further includes a contact sensor 50 that detects contact between the headrest 2 and the user's head A, a position changing mechanism 60 that moves the center speaker 13 in the -X direction by a predetermined distance in response to an instruction from the control unit 70, and a control unit 70 that controls the entire speaker system 1A. When receiving the detection information of the contact sensor 50, the control unit 70 controls the position changing mechanism 60 so as to change the position of the center speaker 13 in the X direction. The position changing mechanism 60 moves the center speaker 13 in the -X direction by a predetermined distance in response to an instruction from the control unit 70. By configuring the speaker system 1A in this way, the position of the center speaker 13 in the X direction can be adjusted according to whether the user has the head A attached to the headrest 2 or the head A is separated. As a result, in addition to the effect of the speaker system 1 according to the first embodiment, the sound of the positive phase (in-phase) emitted from the right speaker 11 and the left speaker 12 can be delivered to the user at a short distance while distancing the sound of the opposite phase emitted from the center speaker 13. That is, since the center speaker 13 that reproduces the opposite phase is not placed near the user's ear, the sound of the opposite phase is less likely to be heard by the user, and as a result, the sound quality of the sound heard by the user is improved.

[0072] As described above, the present disclosure has been described with reference to the embodiments, but the present disclosure is not limited to the above-described embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. And each embodiment can be combined with other embodiments as appropriate.

[0073] Each drawing is merely an illustration for explaining one or more embodiments. Each drawing may be associated with not only one specific embodiment but also one or more other embodiments. As can be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with the features or steps shown in one or more other drawings to create, for example, embodiments that are not explicitly illustrated or described. Not all of the features or steps shown in any one drawing for explaining exemplary embodiments are necessarily essential, and some features or steps may be omitted. The order of the steps described in any drawing may be changed as appropriate.

Description of Reference Numerals

[0074] 1, 1A Speaker system 11 Right speaker 12 Left speaker 13 Center speaker 111, 121, 131 Diaphragm 112, 122, 132 Magnetic circuit section 113, 123, 133 Flat baffle 114, 124, 134 Speaker terminal (+ side) 115, 125, 135 Speaker terminal (- side) 2 Headrest 30 Frame 40 Cushion material 50 Contact sensor 60 Position changing mechanism 70 Control unit 100 Acoustic system 3 Amplifier 31 - 34 Amplifier terminals 301 - 305 Wiring cords D1 Speaker diameter D2 Outer diameter of magnetic circuit section A User's head W Width of head S1, S2, S11, S12, S21, S22 Sound fields SP Sound pressure observation surface

Claims

1. A right speaker that emits sound for the right ear based on an audio signal, a left speaker that emits sound for the left ear based on the audio signal, a center speaker disposed between the right speaker and the left speaker and emitting the sound for the right ear and the sound for the left ear based on the audio signal, comprising: the right speaker, the left speaker, and the center speaker are each attached to a planar baffle, the center speaker is arranged such that its sound emission direction is opposite to the sound emission directions of the right speaker and the left speaker, a speaker system.

2. The diaphragm of the center speaker is disposed at a position offset from the diaphragms of the right speaker and the left speaker with respect to the sound emission directions of the right speaker and the left speaker, The speaker system according to claim 1.

3. The speaker system is provided in a headrest of a seat or a chair, the diaphragm of the right speaker is arranged such that the central position in its lateral width direction is near the rear of the right ear of the user of the speaker system, and the diaphragm of the left speaker is arranged such that the central position in its lateral width direction is near the rear of the left ear of the user, The speaker system according to claim 2.

4. a contact sensor that detects contact between the headrest and the user's head, a position changing mechanism that changes the position of the center speaker according to the detection result of the contact sensor, The speaker system according to claim 3, further comprising.

5. The speaker system according to any one of claims 1 to 4, an amplifier that outputs a stereo audio signal for the right ear and a stereo audio signal for the left ear, comprising: the right speaker, the left speaker, and the center speaker of the speaker system each have a positive terminal and a negative terminal to which the stereo audio signal is input from the amplifier, the amplifier has a positive terminal and a negative terminal for each of the stereo audio signal for the right ear and the stereo audio signal for the left ear corresponding to the right speaker, the left speaker, and the center speaker, the right speaker, the left speaker, and the center speaker and the amplifier are The plus terminal for the right ear of the amplifier is connected to the plus terminal of the right speaker, the plus terminal for the left ear of the amplifier is connected to the plus terminal of the left speaker, and the minus terminal for the right ear of the amplifier is connected to the minus terminal of the center speaker. The plus terminal of the center speaker is connected to the minus terminals of the right speaker and the left speaker. Audio system.

Images