JP4338102B1 - Speaker system - Google Patents

Abstract

[PROBLEMS] To reduce the size of the mid- and high-frequency range of a spherical speaker system using a pseudo-breathing ball system by "miniaturizing the housing" and "promoting the attenuation of standing waves and suppressing the mutual interference caused by direct back waves between speaker units". It aims to improve the sound quality over the entire frequency band by improving the peak and gap of the frequency characteristics and improving the sound quality, and efficiently compensating for the lowering of the low frequency reproduction capability due to the lack of the housing capacity.
In a speaker system 10 in which a plurality of equivalent speaker units 13 are evenly arranged on the surface of a spherical housing 11 and driven in the same phase as in a pseudo respiratory sphere type omnidirectional spherical speaker system 10, each speaker unit A housing inner side opening 16 of the acoustic port 15 for reinforcing the low frequency range by Helmholtz resonance is disposed at a position equidistant from 13.
[Selection] Figure 1

Description

  The present invention relates to a speaker system for high-quality sound field reproduction.

High-quality sound field reproduction is to faithfully reproduce the original sound recorded in a concert hall or studio as if the player was invited to the living room at home, and even the skill of the player and the acoustic characteristics of the recording site. However, the present inventor believes that it is possible to talk about the artistry beyond that if there is reproducibility that is not modified from the entrance to the exit of the sound at all.
In other words, speaker systems should specialize in the function of faithfully converting all input electrical signals into sound waves and radiating them into the listening space, that is, output directivity frequency characteristics and output sound pressure frequency characteristics. In any case, a flat speaker system is truly a high performance speaker system suitable for high-quality sound field reproduction.

  The present inventor has already stated in the specification of Japanese Patent Application No. 2007-223570 that a “point sound source / omnidirectional speaker system” is ideal for high-quality sound field reproduction. However, this “point sound source / omnidirectional speaker system” is only a theoretical ideal image, and as the closest realization method at present, as shown in FIG. A “pseudo respiratory sphere method” that imitates a “rubber-like sphere that radiates sound pressure to the outside by expanding and contracting (respiratory sphere)” by evenly arranging and driving in phase on the top (output) The approximate state of the wave is shown in FIG. In the figure, reference numerals 2a to 2d denote speaker units as a plurality of equivalent sound sources.

  The practical application of the “pseudo respiratory sphere method” has already been attempted by many pioneers, but as far as the inventors of the present application are aware, all of them still have some problems, and have yet to be completed. It is difficult to say, but the following are examples and the remaining issues.

  First, as a simpler method, a “pseudo respiratory sphere type” spherical speaker system in which a plurality of equivalent speaker units are arranged on the surface of a spherical or regular spherical body called a regular dodecahedron or 32-hedron and driven in phase is disclosed in Patent Literature 1 and Patent Literature 2 and Patent Literature 3 are many, but unfortunately, all of them are simply "arranged a plurality of speaker units on the surface of a spherical body called a spherical or regular dodecahedron or thirty-hedron to drive in phase." Is described in (b) of paragraph [0004] of Patent Document 1 and shown in the graph of [FIG. 3], and is described in paragraph [0003] of Patent Document 2 [FIG. 4 (A)]. Furthermore, as shown in paragraph [0004] of Patent Document 3 and shown in the graph of [FIG. 5], a flat output directivity frequency characteristic can be realized. And yet it not, is going to get a flat output directional frequency characteristic by adding a complex electronic (electric) circuit Treat correction to the input signal provided to the preceding stage.

  On the other hand, by implementing “a configuration in which all the faces of a regular dodecahedron having a diameter of less than 10 cm (actually 11 faces) are driven by a drive unit corresponding to each diaphragm as described in Patent Document 4”, Victor's pulsing sphere, which has already been announced on the market as being close to the “breathing ball”, has achieved a remarkable effect in flattening the reproduction directivity frequency characteristics in the middle and high frequencies. The main factor is that it depends on the fact that it does not have a housing. For this reason, a speaker unit with a very complicated structure is newly created (the applicant refers to it as an “electroacoustic transducer”). In addition, because of its small external shape, sufficient bass reproduction capability cannot be obtained, and a separate woofer (speaker unit dedicated to low range reproduction) is externally attached. It is supplemented with.

  In addition to these Patent Documents 1 to 4, a speaker system that employs a “pseudo respiratory sphere method” in which a plurality of speaker units are evenly arranged on the surface of a spherical housing and driven in the same phase is generally 1) a large peak or gap in output characteristics. It is well known among those skilled in the art that 2) the efficiency is significantly reduced in the high frequency range, and 3) the reproduction capability is insufficient in the low frequency range. High-quality sound field reproduction is realized with a simple and low-cost configuration consisting of only a speaker unit and a housing without requiring electrical (electronic) correction of the input signal, no matter what pseudo-bulb system or spherical speaker system is viewed. A spherical speaker system that can be used is not found as far as the inventors of the present application know.

  The inventor of the present application, among the above-mentioned “problems of the pseudo respiratory sphere system / spherical speaker system”, particularly 1) and 2), contributed to the cause as described in the specification of Japanese Patent Application No. 2007-223570. “A standing wave generated in a spherical enclosure and due to mutual interference between speaker units” and “Means to promote attenuation of standing waves and prevent mutual interference due to direct back waves between speaker units” The improvement was seen by placing a polyhedral rigid body that has no surface parallel to the inner wall of the spherical enclosure at the approximate center of the spherical enclosure. Further, according to a separate analysis by the inventor of the present application, the above-mentioned problems 1) and 2) indicate that the “point sound source” aimed by the “pseudo respiratory sphere method” is theoretically one sound source, whereas the “pseudo respiratory sphere” The “system” is caused by having a plurality of sound sources. To solve the problem, it is effective to make the outer shape of the speaker system smaller (in fact, comparing the above-mentioned Patent Documents 1 to 4 from this viewpoint). In the middle and high sound ranges, it can also be confirmed that the reproduction directivity frequency characteristic of Patent Document 4 whose outer shape is extremely smaller than the other is remarkably superior). For other reasons, for example, in terms of manufacturing cost and freedom of installation, the pseudo-breathing ball type speaker system has never been small in size, while the bass is generally “large in volume. It is also a fact that it is “advantageous”, and improving the above-mentioned problems 1) and 2) will increase the problem of “insufficient reproduction capability in the low sound range” in 3). With respect to this dilemma, each of the applicants of Patent Documents 1 to 4 seeks a compromise with coping therapy means such as “input signal correction” and “external woofer” as described above.

In general, when the housing capacity is limited, a method called a phase inversion type (bass reflex type) is often adopted to improve the performance in the low sound range.
The phase inversion type is a Helmholtz resonance at a specific frequency (low frequency range to be reinforced) determined by the intrinsic constant of the speaker unit used, the volume inside the housing, and the opening area and length of the acoustic port called the bass reflex duct that connects the inside and outside of the housing. Is used to reverse the phase of sound waves radiated from the back of the speaker unit diaphragm into the enclosure, and align it with the phase of sound waves from the front of the diaphragm, and release it from the outside opening of the enclosure through the acoustic port. This is a mechanism that reinforces the original bass reproduction capability of the unit used by synergizing with the sound waves radiated from the front surface of the speaker unit diaphragm, and is a very popular method in modern speaker systems.

However, in reality, in the speaker system using this phase inversion type, even if the amount of bass can be increased, the quality of the bass is cloudy or there is no tightness, so-called bass reflex smell is felt. It was hard to say that the sound quality was high quality.
Japanese Patent Laid-Open No. 9-70092 Japanese Patent Laid-Open No. 2005-05694 JP-A-10-341493 Japanese Patent Laid-Open No. 2006-311349

  The present invention aims to improve the sound quality over the entire frequency band of the spherical speaker system adopting the pseudo respiratory sphere method in order to realize a high-quality sound field reproduction, and includes “input signal correction” and “external woofer”. Even without relying on coping therapy measures, it is possible to reduce the size of the chassis and to promote the attenuation of standing waves generated in the chassis and to suppress the mutual interference caused by the direct back waves between the speaker units.・ Improve the peak and gap of the frequency characteristics in the high frequency range and improve the sound quality, and make it possible to reproduce rich and high-quality low frequency range by compensating for the decrease in the low frequency range reproduction capability due to the lack of the housing capacity. Thus, the sound quality is improved over the entire frequency band.

In order to solve the above-described problem, the present invention includes a plurality of speaker units sharing the internal space of the casing as a common back cavity on the surface of one casing, and all the speaker units are connected to the speaker unit. A speaker system that is arranged on the surface of the casing and driven in phase with a positional relationship in which there is a point P0 where the sum of vectors of acoustic energy radiated directly from the back of each diaphragm is always zero, A cylindrical shape in which a casing inner opening (inlet) is disposed at the point P0 which is also a position where the distances from the diaphragm centers of all the speaker units are equal, and a casing outer opening (exit) is disposed on the surface of the casing . With acoustic port.
In addition, if the casing is spherical or cylindrical, the shape of the acoustic port does not have any plane parallel to any of the inner wall surfaces of the casing, and any diaphragm back surface of the speaker unit Both have a shape that has no parallel surface.
In addition, when the casing is cylindrical, the acoustic port is disposed on the central axis of the casing along the central axis.
Further, in the speaker unit and another speaker unit having a positional relationship opposite to each other across the speaker unit and the acoustic port, the size of the inner opening (entrance) of the acoustic port is set to It should be larger than the size of the image projected directly behind the diaphragm.
However, "back cavity" refers to that of the closed space speaker unit emits sound waves from the rear diaphragm, "a plurality of similar speaker units sharing an internal space of the housing as a common back cavity "Means that all of a plurality of equivalent speaker units emit sound waves from the back surface of the diaphragm into the same enclosure space.
In addition, "plural equivalent speaker units" here means basically the same manufacturer and the same model, such as minimum resonance frequency, effective diaphragm area, vibration system equivalent mass, equivalent Q, efficiency, etc. The characteristic error within the range of common sense as a mass-produced product is acceptable. This also includes the meaning that the same manufacturer and the same type are not necessarily required if the specifications such as the minimum resonance frequency, effective diaphragm radius, vibration system equivalent mass, equivalent Q, and efficiency are the same. That is, it includes the meaning of a speaker unit group that obtains substantially the same output for the same input.
The “position where the distances from the center of the diaphragms of all the speaker units are equal” is not strictly “equal”, but within the range where the effects of the present invention described below can be obtained (specifically, from experiments) Error tolerance within about 10 percent of the distance from the speaker unit) is allowed, and the same applies to the following similar notations.
Further, the “cylindrical shape” is not limited to a circular cross-sectional shape, but may be a square shape, an elliptical shape, or a cylindrical shape that forms an arbitrary cross-sectional shape.

In this way, there is at least a “point where the distances from the center of each speaker unit diaphragm are all equal” at which the acoustic port entrance should be placed, and directly behind the back of each diaphragm of a plurality of equivalent speaker units that drive in phase. In order for there to be a point (P0) where the sum of the vectors (direction and magnitude) of the radiated acoustic energy is always zero , all speaker units are evenly arranged on the same circumference and the center of the circumference Must be mounted from the center of the sphere in the radial direction, or all speaker units must be evenly arranged on the same spherical surface. Here, “from the center toward the radial direction” means to install the speaker unit so that the rear surface of the speaker unit faces the circumference or the center of the sphere . “ Equally arranged on the same circumference” means that n (n is an integer of 2 or more) speaker units are placed on the circumference at an angle of [360 / n] degrees from the center of the circumference. For example, when there are three speaker units, each speaker unit is arranged on the same circumference at an angle of 120 degrees from the center of the circumference. Furthermore, this circumference does not have to be unique, and even if there are multiple circumferences, if all of their centers overlap as the only point, they can be placed evenly on each circumference, and this arrangement is on the same sphere. In other words, all the speaker units are installed evenly on a plurality of circumferences around the center of the sphere and directed radially from the center of the sphere.
In addition, “equally arrange on the same spherical surface” is to arrange each speaker unit at the center of gravity of each area when the entire surface of the sphere is equally divided into the same area and shape by the number of speaker units. For example, it is also possible to arrange all speaker units equally on the same circumference around the center of the sphere on the surface of the sphere. However, if the number of speaker units is four, the sphere is circumscribed. The position of the center of each surface of the regular tetrahedron or the position of each of the vertices of the regular tetrahedron inscribed in the sphere. Is placed at each vertex of the regular octahedron inscribed in the case, or in the case of eight at the center of each surface of the regular octahedron circumscribed by the sphere or at each vertex of the regular hexahedron inscribed in the sphere It is arranged three-dimensionally, such as It is also possible (this arrangement is also a typical configuration itself of the pseudo breathing sphere system, omnidirectional spherical speaker system).
In any of the above arrangements, “the center of the circumference” and “the center of the sphere” coincide with “the positions where the distances from all the speaker unit diaphragm centers are equal” where the acoustic port entrance is to be placed.

A plurality of speaker units that share the internal space of the casing as a common back cavity are provided on the surface of one casing, and all of the speaker units are radiated directly from the back of each diaphragm of the speaker unit. A speaker system that is arranged on the surface of the housing and has the same phase drive with a positional relationship where a point P0 where the sum of vectors of acoustic energy is always zero exists, and the distances from the diaphragm centers of all the speaker units By providing a cylindrical acoustic port in which the housing inner opening (entrance) is disposed at the point P0 where the positions are equal and the housing outer opening (outlet) is disposed on the surface of the housing , Low-frequency reinforcement by the phase inversion method that seems to have reached the highest quality in terms of quantity and quality without the “bass reflex odor” Possible reinforcement and then, to enable playback more high-quality bass.

Furthermore , in the low frequency range, in addition to the low frequency range reinforcement effect of the conventional phase inversion type Holm Hertz resonance, the low frequency range reinforcement effect by the compression of acoustic energy is obtained, and in the middle and high frequency range, The acoustic port is defined as follows: “If the housing is spherical or cylindrical, the shape of the acoustic port does not have any surface parallel to any of the inner wall surfaces of the housing and any of the speaker units. "If the casing is cylindrical, the acoustic port is arranged along the central axis on the central axis of the casing." Or “in the speaker unit and another speaker unit that is opposite to each other with the speaker unit and the acoustic port interposed therebetween, the inner opening of the acoustic port ( The size of the mouth), the diaphragm of the speaker unit and more than the size of the image projected onto the true rear "encourage attenuation of" standing wave by, suppress mutual interference due to the direct back wave between the speaker unit to "-out work as a structure, which makes it possible to improve the peak and the gap of the output characteristics of the middle and higher frequencies, the result, play a significant improvement in sound quality over the reproduction frequency band throughout.

  First, regarding the low frequency range, the above-mentioned “bass reflex odor” is mainly caused by insufficient rigidity of the housing or inappropriate setting of the dimensions of the acoustic port (opening area, port length, resonance frequency, mounting position, etc.) However, in particular, the inventor of the present application pays attention to the sound wave waveform introduced into the bass reflex duct, in order to draw out the possibility of further improvement in sound quality of the phase inversion method that seems to have already reached maturity, First, the “sound field consisting of a plurality of sound sources” was analyzed as follows.

  In FIG. 8, (a) is a diagram showing the spread of sound as seen from the direction perpendicular to the straight line connecting both sound sources when sine waves are simultaneously output from the two sound sources A and B. Yes, (b) shows three planes of A, B, and C arranged at non-equal intervals on the same circumference, and the same phase and sine waves are output simultaneously from each source, with respect to the plane surrounded by the circumference. (C) shows three sound sources A, B, and C on the same circumference at equal intervals (equal) at an angle of 120 degrees from the center O of the circumference. It is the figure which expressed the expansion of the sound seen from the perpendicular | vertical direction with respect to the plane enclosed by the circumference when arrange | positioning and outputting the sine wave simultaneously from each sound source. FIG. 9 is a graph showing the arrival waveforms (synthesized waveforms from the sound sources) at the points P1 to P10 over time when the two phases of the sine wave are simultaneously output from the sound sources in FIG. (However, attenuation of sound due to propagation in the air is ignored). Here, the reason why the output from each sound source is only two cycles of the sine wave is that the sound signal of the source such as music handled by the speaker system for high-quality sound field reproduction is a stationary sine wave used for general measurement etc. Unlike frequency, the frequency and amplitude always change, and in order to determine whether the output is faithful to the input, it is not a stationary wave that repeats the same waveform endlessly, but one or two cycles that can be said to be transient characteristics. This is because it is important to look at the responsiveness (reproducibility) to the input.

  From FIG. 8 and FIG. 9, at each point of P1, P2, P4, and P7, a composite waveform whose waveform is similar to the output from each sound source and whose magnitude is equal to the sum of the outputs from each sound source can be observed. On the other hand, at other points P3, P5, P6, P8, P9, and P10, the observed waveform and size are different from those output from each sound source. Each point of P1, P2, P4, and P7 is a point that is equidistant from all sound sources. Therefore, when two phases of sine waves are simultaneously output from a plurality of sound sources, all the sound sources, etc. Only in terms of distance, it can be seen that a composite waveform similar to the output from each sound source and having a magnitude equal to the sum of the outputs from each sound source can be observed.

  For example, when actually listening to the sound of the waveforms of P3 and P5 in FIG. 8, compared to the original sound output from each of the sound sources A, B, and C, the sound is “bad sound” and “untightened sound”. Hearing, the waveforms of P6, P8, P9, and P10 are heard as “distorted sound” or “different sound”. The degree of deformation of the composite waveform is smaller as the wavelength of the sound wave is longer with respect to the distance difference from each sound source. In the low frequency range handled by the phase inversion method, the wavelength is sufficiently long relative to the size of the enclosure, so the deformation of the composite waveform due to the difference in arrival time from each sound source is very small. This difference is sufficient to feel as “difference in tone” and “discomfort”.

  Applying this "analysis of the sound field by multiple sound sources" to an actual speaker system, as described above, the phase inversion method is "the sound wave radiated from the back of the speaker unit diaphragm to the enclosure." By reversing the phase of the sound through the bass reflex duct, the phase is aligned with the “sound wave radiated from the front surface of the speaker unit diaphragm to the outside of the enclosure” and emitted from the outside opening of the bass reflex duct to the outside of the enclosure. Since it is a mechanism that reinforces the original bass reproduction capability of the unit used by synergizing with the sound waves radiated from the front of the unit diaphragm, “the waveform of the sound waves radiated from the front of the speaker unit diaphragm” and “each speaker unit Inverts the phase of the composite wave of sound waves that are radiated from the back of the diaphragm into the enclosure and reach the inside opening of the bass reflex duct. If the waveform does not match, naturally, the combined waveform, that is, the output waveform of the entire phase-inverted speaker system will be different from the original waveform (input signal). If the two waveforms match, the bass region is reinforced with the highest efficiency and quality, and bass reproduction that is more faithful to the input, that is, high-quality bass reproduction can be achieved.

  Strictly speaking, the sound wave emitted from the bass reflex duct outer opening relative to the sound wave radiated from the front surface of the speaker unit diaphragm is applied at least until the sound wave from each speaker unit reaches the inner opening of the bass reflex duct housing. In order to cause a time lag more than time, that is, a phase shift, even if “the waveform of the sound wave radiated from the front surface of the speaker unit diaphragm” and “the inner surface of the bass reflex duct is radiated from the rear surface of the speaker unit diaphragm. Even if both of the waveforms obtained by inverting the waveform of the sound wave reaching the opening are completely similar to each other, the synthesized waveform, that is, the output waveform of the entire speaker system is damaged. Therefore, the position of the opening of the bass reflex duct must be as close as possible to each speaker unit. However, “the waveform of the sound wave radiated from the front surface of the speaker unit diaphragm” and “ Compared to the case where both of the “waveforms obtained by inverting the phase of the composite wave of the sound waves radiated from the back of each speaker unit diaphragm to the inside opening of the bass reflex duct” are different from the original, this phase inversion It is clear that the output waveform of the whole type speaker system is closer to the original form (input waveform).

  As described above, a speaker system that drives a plurality of identical speaker units that share the internal space of a single chassis as a common back cavity in the same phase can be of any shape, not limited to a spherical shape or a rectangular shape. The waveform is always similar to the “waveform of sound wave output from each speaker unit” and the magnitude is “the sum of the outputs from each speaker unit” only at “points that are equidistant from each speaker unit”. In the present invention, as shown in FIGS. 1 and 2 (a) to 2 (c), the position of the "inner opening of the acoustic port (bass reflex duct)" is set to "each speaker". By arranging only at “points that are equidistant from the unit”, the low-frequency range reinforcing effect by the phase inversion method is maximized in terms of both quantity and quality.

This feature will be described in more detail with reference to FIG.
(A) is one in which two equivalent speaker units are attached to a certain plane on the surface of the housing. In this figure, there are innumerable “points that are equidistant from each speaker unit”, which is the point where the housing inner opening of the acoustic port according to the present invention should be placed, “Points that are equidistant from each speaker unit” exist innumerably on a plane that includes the two-dot chain line orthogonal to the straight line connecting the SP1 and SP2 speaker units and the midpoint of SP1 to SP2. However, when three or more speaker units are arranged on one plane, there is no “point that is equidistant from each speaker unit” unless they are arranged on the same circumference on the plane. “Points that are equidistant from each speaker unit mounted on the same circumference on the same plane” are innumerable on a straight line passing through the center of the circumference and orthogonal to the plane.
(B) has a part of a cylindrical curved surface on the surface of the housing, and a plurality (three) of equivalent speaker units are arranged on the curved surface on the same circumference around the center of curvature O of the cylindrical curved surface. It is attached in a direction that is a radial direction from the circumferential center O. In this figure, “a point that is equidistant from each speaker unit” is only one point of the circumference center O, but in reality, it is on a straight line that passes through the center O and is orthogonal to the plane surrounded by the circumference. Innumerable. Further, when this cylindrical curved surface is a spherical surface, “a point that is equidistant from each speaker unit” is only one point of the center O of a sphere that includes this spherical surface as a part.
(C) shows a plurality of (three) equivalent speakers on the circumference centered at one point on the central axis of the cylinder on the cylindrical surface which is the side surface of the cylindrical casing with the circular plane of the cylinder as the top and bottom. The units (SP1, SP2, SP3) are arranged uniformly (with an angle of 120 degrees from the center point O of the circumference), and are installed in a direction that is a radial direction from the center O of the circumference. In this figure, “a point that is equidistant from each speaker unit” is only one point of the circumference center O, but actually, it is on a straight line that passes through the center O and is orthogonal to the plane surrounded by the circumference. In other words, there are countless numbers on the central axis of the cylindrical casing. The speaker system that implements this configuration is most easily associated with a columnar enclosure that has two circular planes of the cylinder as top and bottom and a cylindrical curved surface as a side. There is a horizontal and omnidirectional speaker system in which a plurality of equivalent speaker units are uniformly arranged on the same circumference as the center. However, the present invention is not limited to a columnar shape and can be applied to all regular polygonal columnar casings.
Further, (c) shows that a spherical body has a uniform (circle) multiple (three) equivalent speaker units (SP1, SP2, SP3) on the same circumference centered on the center of the body on the surface of the body. It is also shown that it is arranged at an angle of 120 degrees from the center point O of the circumference and installed in a direction that is a radial direction from the circumference center O. Even in this case, in the figure, “a point that is equidistant from each speaker unit” is only one point of the circumference center O, but actually, the point is perpendicular to the plane surrounded by the circumference and passes through the center O. There are countless numbers on a straight line. However, if the positions of a plurality of equivalent speaker units are not limited to the same circumference, only in a case having a spherical surface such as a spherical case, the “points that are equidistant from each speaker unit” There can be only one point at the center O of the sphere.

  As described above, in any of the speaker systems shown in FIGS. 2A to 2C, there is a “point that is equidistant from each speaker unit”, and there is an “acoustic port ( By restricting the arrangement of the “inner opening of the bass reflex duct)”, the low-frequency range reinforcing effect by the phase inversion method is maximized in terms of both quantity and quality. However, when there are a plurality of “points that are equidistant from each speaker unit”, considering the description in paragraph [0021] of the present specification, the position of the opening of the acoustic port in the housing is set as much as possible to each speaker unit. Should be close to

Next, the sum of the vectors (direction and size) of acoustic energy radiated from the back of each diaphragm of a plurality of equivalent speaker units that share the internal space of the single chassis as a common back cavity is A speaker system in which all the speaker units are arranged on the surface of the housing with a positional relationship in which a point P0 that is always zero exists, and is driven in the same phase, and from the diaphragms of all the speaker units inside the housing The speaker system having a cylindrical acoustic port in which a housing inner opening (entrance) is disposed at the point P0, which is also a position where the distances of the housings are equal, and a housing inner opening (exit) is disposed on the surface of the housing , In addition to the bass intensifying effect by the phase inversion type, the following “further bass intensifying effect” is brought about.

  Since the wavelength of the low frequency range used in the phase inversion method is sufficiently large compared to the internal space dimensions, the sound is not a "wave that travels in the air". It can be regarded as “air density (atmospheric pressure fluctuation) moving from the diaphragm toward the amplitude direction with time”, or “reciprocating wind” more easily. The sound energy vector of the low-frequency sound wave radiated from the back of the speaker unit to the back is considered as “wind”. The sound energy vector radiated from the back of each diaphragm of the speaker unit “All in size” are balanced at a single point ”, as shown in FIG. 3,“ the wind that blows from all the speaker units toward the back is directed to a certain point in the enclosure. They collide with each other and lose their escape to balance the strength and direction of the wind. As a result, they are compressed at that one point. Due to this compression action, at one point, it is possible to obtain an energy density that is equal to or greater than the sum of the loudness of sound emitted from each speaker unit.

As described above, “all the point relationships where the sum of the vectors (direction and magnitude) of the acoustic energy radiated from the back of the diaphragm of each speaker unit to the back is always zero are present . “Speaker units are arranged on the housing surface” means “all speaker units are evenly arranged on the same circumference and attached in the radial direction from the center of the circumference” or “all speaker units are placed The center of the circumference and the center of the sphere at this time are radiated from the back of the diaphragm of each speaker unit to the back. Point P0 where the sum of acoustic energy vectors (direction and magnitude) is always zero , and the acoustic port housing inner opening should be placed “of all the speaker units This is the “position where the distance from the diaphragm becomes equal”. That is, taking in the acoustic energy whose density has been increased by the compression action described above into the acoustic port opening placed in the immediate vicinity of the acoustic energy brings about a bass reinforcement effect that is higher than that of the normal phase inversion method. Furthermore, with this configuration, the distance from the inner opening of the acoustic port housing to each speaker unit is the shortest, which is advantageous in consideration of acoustic energy loss due to propagation in air and the description in paragraph [0021] of the present specification.

  As a speaker system that implements this feature, in the cylindrical and spherical speaker systems shown in FIG. 2 (c), in particular, in the cylindrical casing, at one point in the center of the same circumference where the speaker unit is installed, In the spherical housing, the opening inside the housing of the acoustic port is placed at one point in the center of the sphere. In particular, as shown in FIG. 1, in the configuration in which the speaker units are uniformly arranged three-dimensionally on the surface of the spherical housing (a typical configuration of the pseudo respiratory sphere method / omnidirectional spherical speaker system), the speaker unit is located at the center of the spherical housing. The aggregated acoustic energy vectors have no escape in any of the three-dimensional directions, and can be said to be the best mode for carrying out the present invention since the compression action at the opening inside the housing of the acoustic port can be most expected.

  Up to this point, the effect of the present invention contributing to the improvement of the sound quality in the low frequency range has been described, but by implementing the features of the present invention, an acoustic port or a spherical enclosure installed so as to overlap the central axis of the cylindrical enclosure. An acoustic port with a housing inner opening at the center of the horn is an obstacle in the middle and high sound range when the speaker unit is responsible for the reproduction range up to the high sound range (used as a full range speaker) Therefore, as shown below, the sound quality is improved even in the middle and high frequency ranges.

  First, in general, a “standing wave” generated in the speaker system housing has a great adverse effect on the reproduced sound quality over a wide band. As shown in FIG. 4 (a), in a cylindrical enclosure, a concentric standing wave that repeats aggregation and divergence toward the central axis of the cylinder, and in a spherical enclosure, at the center of the sphere. A spherical wave standing wave that repeats aggregation and divergence in the opposite direction is generated. This is a collection of "fine parallel plane pairs" in which the inner wall of a cylinder or sphere faces each other across the cylinder axis or the center of the sphere. It comes from something. Theoretically, of the reflected waves from the enclosure wall, the sound wave with a frequency (multiple) whose wavelength is a divisor of the enclosure space diameter continues to reciprocate (oscillate) between "a pair of fine parallel planes". The standing wave generated in can be prevented by placing an obstacle having a shape that breaks parallelism at a position that blocks all of the “fine parallel plane pairs”.

Specifically, in the case of a cylindrical housing, a rigid body such as a triangular prism or the like that has as few sides as possible is placed in the same direction as the central axis. Although the occurrence of standing waves can be prevented, in the present invention, the acoustic port plays the role of this “polygonal column rigid body”.
In this case, as shown in FIG. 4B, the acoustic port diffuses and reflects the standing wave collected on the central axis of the cylindrical casing to promote attenuation and extinction thereof. In addition, this configuration is not limited to a cylindrical casing, and the same effect can be obtained even in a substantially cylindrical (a regular polygonal column having at least six side walls) having an even number of side wall surfaces.
In addition, the external shape of the acoustic port in a cylindrical casing is “cannot be cylindrical” because the combination of the cylindrical casing and the cylindrical acoustic port is between the outer surface of the acoustic port and the inner wall of the casing. This is because an infinite number of “fine pairs of parallel surfaces” are formed again, and a new standing wave is generated between them. Similarly, in the case of a substantially cylindrical housing having an even number of side wall surfaces, pay attention to the orientation and shape of the side surface of the acoustic port so that there is no parallel surface between the outer surface of the acoustic port and the inner surface of the side wall of the housing. There is a need to. In addition, when the length of the acoustic port is short with respect to the height of the cylindrical casing, it is necessary to install a rigid body of a polygonal column as a dummy so as to extend the acoustic port. Furthermore, in the case of a substantially cylindrical housing, the external shape of the acoustic port is determined by the width of each side wall surface between the housing side wall surfaces where the projected widths of the acoustic ports face each other (the length of one side of the regular polygon on the ceiling). It is more effective to make the above.

Next, in the case of a spherical housing, specifically, the occurrence of standing waves can be prevented by placing a polyhedron with as few faces as possible (such as a spherical shape) such as a tetrahedron at the center of the sphere. In the present invention, however, the acoustic port plays the role of the “polyhedral rigid body”.
In the spherical housing, the external shape of the acoustic port housing inside the vicinity of the opening inside the acoustic port housing is not a tetrahedron, and as shown in FIG. As a result, the damping and extinction are promoted, and the effect as a “rigid body that prevents the generation of standing waves” in the spherical body is exhibited. Further, this configuration is not limited to a spherical shape, and the same effect can be obtained even in a substantially spherical casing such as a regular dodecahedron or a thirty-two-hedron.
In addition, the reason why the outer shape in the vicinity of the inner opening of the acoustic port housing in the spherical housing is “cannot be spherical” is that the combination of the spherical housing and the acoustic port in which the outer shape of the inner opening end of the housing is spherical This is because an infinite number of “fine parallel plane pairs” are again formed between the inner opening end of the port and the inner wall of the port, and a new standing wave is generated between them. Similarly, in the case of a substantially spherical housing, it is necessary to pay attention to the direction and shape of the acoustic port housing inner opening end so that there is no parallel surface between the acoustic port housing inner opening end and the housing wall surface. is there. In the case of a substantially spherical housing, the outer shape of the inner opening of the acoustic boat housing is set to be equal to or larger than the size of each inner wall surface between the inner wall surfaces of the acoustic port housing inner opening facing each other. Is more effective.

  Next, in general, when a plurality of equivalent speaker units are housed in the same housing, it is necessary to pay attention to “mutual interference” between the speaker units. Originally, when diaphragms having exactly the same specifications are present in the vicinity, they are likely to resonate. In particular, as shown in FIG. Then, the direct back wave radiated directly from the back of the diaphragm of each speaker unit directly reaches the opposite speaker unit and forcibly vibrates the diaphragm, which adversely affects the reproduced sound quality. In order to prevent this “interference between opposing speaker units”, an obstacle that blocks the direct path from the back of the diaphragm of each speaker unit directly reaching the opposing speaker unit. It is effective to put

On the other hand, “putting the acoustic port in the same direction as the central axis at the position of the central axis of the cylindrical casing” and “putting the opening inside the acoustic port casing at the center of the spherical casing” are shown in FIG. , (C), the obstacle forming the acoustic port obstructs the path where the direct back wave radiated directly from the back of the diaphragm of each speaker unit directly reaches the opposite speaker unit. It contributes to the improvement of the reproduction sound quality of the speaker system by preventing the interference between the opposite speaker units.
However, care must be taken so that the structure forming the opening of the acoustic port housing does not have a surface facing the rear surface of the diaphragm of the speaker unit. This is because the direct back wave reflected by the surface returns to the original speaker unit diaphragm and causes self-interference. In addition, it is more effective to make the outer shape of the acoustic boat equal to or larger than the size of the diaphragm of each speaker unit between the speaker units with which the projected images of the acoustic ports are in conflict.

  The two effects mentioned above, "Promoting attenuation and extinction of standing waves in the enclosure" and "Detering mutual interference of speaker units", are no longer beyond the role of bass reflex ducts in the original phase-reversal system. Since the present invention greatly contributes to the improvement of sound quality over the entire frequency band of a cylindrical or spherical speaker system, the inventor of the present application dared to say “acoustic port” instead of “bass reflex duct” in “Claims”. Expressed.

As described above, the present invention is mainly intended to bring about the quantitative and qualitative improvement of the low frequency range in the speaker system. In the actual speaker system, the dedicated low frequency range reproduction is dedicated. If it is a phase inversion type speaker system provided with a plurality of speaker units (woofers), it will be effective regardless of the shape of the housing. Furthermore, in a cylindrical or spherical speaker system, an effect of improving the sound quality over the entire reproduction frequency band as well as the low sound range is exhibited.
In particular, when the present invention is applied to a pseudo respiratory sphere type / omnidirectional spherical speaker system, the effect is most useful and efficient, and the best mode in the spherical speaker system is listed below.

According to the inventor's separate analysis, in the pseudo-respiratory sphere omnidirectional spherical speaker system in which a plurality of equivalent speaker units are evenly arranged on the surface of one spherical enclosure and driven in phase, the outer shape is It has already been described that the smaller the value, the more advantageous for the mid / high range characteristics, but in detail, the smaller the distance between adjacent speaker units, that is, the smaller the outer shape of the case with the same number of speaker units, the outer shape of the case. If the number of speaker units is the same, the more the number of speaker units, the closer the output directivity characteristics in the middle / high range will be flat.
However, in general, increasing the number of speaker units is also effective for low-frequency range reproduction, but as a result, the required housing capacity increases, and as a result, the spherical housing must be enlarged. Furthermore, since the increase in the number of speaker units directly affects the manufacturing cost, we do not want to increase it unnecessarily. Therefore, for high-quality sound field reproduction, the spherical housing should be miniaturized with the minimum number of speaker units that can service the output waves evenly in front, back, left, right, up and down. .
In addition, in the case of a substantially spherical casing, the diffraction and reflection on the outer surface of the casing is better when the outer shape of the casing is smooth and spherical than when the outer shape is left as a regular dodecahedron as in Patent Document 4. Waveform disturbance due to is avoided, and the output directivity characteristic becomes flatter.

  When the embodiment according to the present invention is implemented in a spherical speaker system, as a precondition, "a plurality of equivalent speaker units are uniformly arranged on the surface of the spherical enclosure and driven in phase" is the movement of the vibration system between the speaker units. Since the moments are balanced and offset, the entire speaker system is freed from the influence of the vibration system of each speaker unit, and increasing the degree of freedom in the installation method and location of the speaker system can be said to be a secondary merit.

As described above, the acoustic port with the inner opening at the center of the housing is not only a function of an acoustic filter called a bass reflex duct, but also from standing waves and each speaker unit that are concentrated at the center of the housing. Therefore, it is necessary to provide sufficient mechanical strength so that it does not vibrate itself.
Furthermore, the size of the opening (the size of the structure that forms the opening, not the opening area) is the back surface that reaches directly from one of the pair to the other, particularly when there is a pair of contradicting speaker units. As described above, it is desirable that the projection area is at least as large as the effective diaphragm area of each speaker unit as a sufficient size to block the wave (direct back surface wave).
Furthermore, both the flow rate and flow velocity of the air flowing in the acoustic port are much larger than those in the conventional phase reversal type bass reflex duct, so the inner wall surface of the acoustic port is mirror-polished and smooth at the entrance and exit. It is indispensable to take measures against wind noise, such as taking a round.

In addition, limiting the position of the opening inside the housing of the acoustic port to the center inside the spherical housing is subject to the following design restrictions.
Normally, when designing a phase-inverted speaker system, the required capacity of the housing and the acoustic port capacity (port opening area Next, the minimum duct opening area and port length that do not produce wind noise are also determined from the equivalent effective diaphragm area of the speaker unit and the restriction on the air flow rate in the duct. At this time, in order to “position the position of the opening inside the housing of the acoustic port at the center inside the spherical housing”, which is a feature of the present invention, the outer diameter of the housing must be made twice the acoustic port length. Don't be. You must find dimensions that meet all of these conditions, including the plate thickness necessary to ensure the strength of the enclosure, and if the calculated port length is too large, the sound quality in the middle and high frequencies This is dealt with by increasing the diameter of the housing that would damage the sound, and by bending the acoustic port to gain the required length or increasing the number of acoustic ports. Still, if all the conditions are not met, you should consider changing the specifications of the speaker unit itself.

  In the above, the best mode for carrying out the present invention for a spherical speaker system has been described. However, in general speaker systems other than a spherical speaker, when the number of speaker units is three or more, “from all speaker units, etc.” In order for at least one “point to be a distance” to exist, all speaker units must be arranged on the same circumference or the same spherical surface. Further, when there are a plurality of “points that are equidistant from all the speaker units”, the position of the opening of the acoustic port in the enclosure is considered as much as possible in consideration of the description in paragraph [0021] of this specification. Note that it should be close to the unit.

  As described above, the phase inversion method is a very popular means that has already been matured, and the basic operating principle of the present invention is that using Helmholtz resonance as in the existing phase inversion speaker system. In spite of this, not only in the existing spherical speaker system but also in the general rectangular speaker system, a precedent that seems to have intentionally limited the position of the opening inside the housing of the bass reflex duct for the same purpose as the present invention Was not found as long as the inventors searched. This is because, until now, those skilled in the art have tended to focus only on the quantitative reinforcement of the bass by the phase inversion type method. This is because of the so-called “Columbus egg” idea obtained based on the analysis from the inventor's unique viewpoint of “behavior of the back wave radiated from the speaker unit”. Even the technical feature that “the position of the duct inner opening of the duct is limited to a position that is equidistant from each speaker unit” would not have been conceived by those skilled in the art.

  In particular, in the case of a speaker system having three or more equivalent speaker units, there is no precedent in which the opening inside the housing of the bass reflex duct is located at an equal distance from all the speaker units. I am convinced that the invention is based on a unique idea.

  Further, the two effects listed in the paragraphs [0029] to [0034] of the present application are based on the idea of the present inventor described in the specification of Japanese Patent Application No. 2007-223570 by the present inventor. It is derived from "Sonic Analysis" and obtained by digging further, so we are convinced that there is no doubt that it is novel and useful.

In order to verify the effect of the present invention, the inventor of the present application designed and manufactured a prototype of a spherical speaker system of the form shown in FIG.
In the speaker system 10 according to the present embodiment, eight speaker units 13 are arranged in a spherical casing 11, and the inner space 12 is shared as a common back cavity, and each of the eight speaker units 13 is shared. An acoustic port housing inner opening (entrance) 16 is formed at a position where the distance from the diaphragm center 14a becomes equal, that is, the housing center 18, and the acoustic port housing outer opening (on the surface of the spherical housing 11). An acoustic port 15 formed with an outlet 17 is provided.
Further, the eight speaker units 13 are arranged at positions that are the centers of the respective faces of the regular octahedron circumscribing the spherical casing 11 or positions that are the vertices of the regular hexahedron inscribed in the spherical casing 11. By arranging the speaker units 13 in this way, all of the vectors of acoustic energy radiated directly rearward from the back surfaces of the diaphragms 14 of all the speaker units 13 are balanced at the housing center 18. In other words, eight speaker units 13 are arranged so that the vectors of these acoustic energies are balanced at the case center 18.
The speaker unit 13 uses eight 1-inch full-range speaker units NSW1-205-8A manufactured by Aura Sound, Inc., which are generally commercially available and easy to obtain, and connects four sets of two connected in series to each other in parallel. The impedance of the entire system 10 was 4 ohms. The speaker unit 13 is unusually small as a full-range speaker unit, and requires a small housing capacity. In addition, the lowest resonance frequency of the speaker unit alone is as high as 220 Hz, and the low-pitched sound reproduction capability is very low. By adopting the spherical housing 11 that implements the features according to the present invention that can reinforce the sound range and suppress the occurrence of standing waves in the housing and the mutual interference between the speaker units 13, a high-quality sound can be obtained. It is expected to be a high-quality spherical speaker system that can withstand field reproduction.

  In setting the dimensions of the chassis, the dimensions satisfying the above-mentioned conditions were derived from the calculation simulation. As a result, the chassis outer diameter = 184 mm, the acoustic port length = 92 mm (half the casing outer diameter), and the acoustic port opening diameter = 25.3 mm (port The thickness is 32mm, which exceeds the effective vibration diameter of the speaker unit), the plate thickness = 15mm, the capacity of the enclosure = about 1.7 liters (subtracting the volume of the contents such as the speaker unit, reinforcing ribs and sound absorbing material) And Helmholtz resonance frequency = about 85 Hz. In addition, after assembling a truncated icosahedron, the box material is a combination of 20 regular hexagonal quince plate with a thickness of 15 mm, 4.1 cm side, and 12 regular pentagonal cherry plate with 4.1 cm side. Each corner of the surface was scraped off by about 4 mm in height, and the entire surface was scraped to make it almost spherical.

The output frequency characteristic of the prototype of the completed speaker system 10 is shown by a solid line in the graph of FIG. In FIG. 6, the broken line indicates the frequency characteristics of the speaker unit 13 alone, and further, the output frequency characteristics when eight speaker units are attached to a sealed rectangular housing having the same volume as the prototype, are indicated by a one-dot chain line. Further, the output frequency characteristic when only the bass reinforcement as the conventional phase inversion type is applied is indicated by a two-dot chain line.
The reproduction sound of the prototype of the speaker system 10 according to the present embodiment has not only the frequency characteristics of the speaker unit 13 alone indicated by the dotted line, but also the bass reinforcement value as the conventional phase inversion type indicated by the two-dot chain line. It is possible to obtain a bass-reinforcing effect that exceeds that, and the mid- and high-frequency ranges are almost identical to the characteristics of the speaker unit 13 by suppressing the peaks and gaps that the prior art has been struggling with. This is the merit of the spherical speaker system. It is understood that a high-quality sound field reproduction is realized by demonstrating the rich amount of information and natural sound spread.

  According to the present invention, the possibility of further improving the sound quality has been found in the phase inversion type method which has already reached the maturity level. Furthermore, by implementing the embodiment according to the present invention, a spherical speaker system that has improved sound quality over the entire frequency band with an unprecedented rational and simple configuration is low cost, This spherical speaker system that has acquired high-quality sound that is recognized as a high-end class among audio enthusiasts, and that can provide a wider range of more compact, clearer, and higher-quality sounds, for example, for loudspeakers in halls. However, the present invention also has a merit in terms of cost, which is much smaller than the number of installations of the conventional unidirectional loudspeaker.

A plurality of (eight) speaker units sharing the internal space of the casing as a common back cavity are provided on the surface of one casing, and all of the speaker units are directly behind the rear surface of each diaphragm of the speaker unit. A speaker system that is arranged on the surface of the housing and is driven in the same phase with a positional relationship where a point P0 where the sum of vectors of acoustic energy radiated to the surface is always zero exists, and the diaphragms of all the speaker units A cylindrical acoustic port is provided in which a housing inner opening (entrance) is disposed at the point P0 which is also a position where the distance from the center is equal, and a housing outer opening (exit) is disposed on the surface of the housing. It is a perspective view showing the Example of the spherical speaker system which does. A speaker system that drives a plurality of equivalent speaker units that share the internal space of a single chassis as a common back cavity in the same phase, and the distances from the diaphragm centers of all the speaker units are equal within the enclosure. It is a figure showing the concrete structure of the speaker system characterized by providing the cylindrical acoustic port which arranges an entrance in the position and arranges an exit on the surface of the above-mentioned (the spread of the output wave from each speaker unit is carried out) (Shown with a dashed line). However, the output directivity characteristic of each speaker unit is flat, and the reflection and diffraction of sound waves by the housing wall surface are ignored. (A) is a speaker system in which a plurality of (two) equivalent speaker units are arranged in one plane on the surface of the housing and driven in the same phase, and the points on the inside of the housing that are equidistant from each speaker unit ( (Any point on the two-dot chain line in the figure corresponds to the case) The inside opening of the acoustic port housing is arranged, and the outside opening of the housing is arranged on the surface of the housing. A speaker system in which multiple (three) equivalent speaker units are installed on the same circumference in the same curved surface from the center O of the circumference in the radial direction and driven in the same phase, equidistant from each speaker unit (C) is a cylindrical shape with the circular plane of the cylinder as the top and bottom, wherein the casing inner opening of the acoustic port is disposed at the center O of the circumference, and the casing outer opening is disposed on the casing surface. On the side of the enclosure A plurality of (three) equivalent speaker units are equally distributed (with an angle of 120 degrees from the center O of the circumference) on the circumference of the cylinder surface around one point on the center axis of the cylinder. And it is installed in the direction which becomes the radial direction from this circumferential center O. Further, (c) is the same as in the spherical case, and a plurality of (three) equivalent speaker units are equally (120 degrees from the center O of the circumference) on the same circumference around the center of the case on the surface of the case. It is also a diagram showing what is arranged in an angle) and installed in a direction that is a radial direction from the circumferential center O. A speaker system (horizontal omnidirectional speaker system) that drives a plurality of equivalent speaker units arranged in the same phase on the same circumference centered at one point O on the cylinder central axis on the side wall of the cylindrical enclosure In the case of a speaker system (omnidirectional speaker system) that drives a plurality of equivalent speaker units that are evenly arranged on the surface of a spherical or spherical housing in the same phase, a back wave from each of the plurality of equivalent speaker units It is the figure which imaged and represented a mode that was collected and compressed to the point O on a cylindrical rod center axis | shaft, or the spherical rod center O. (A) is a diagram schematically showing the behavior of standing waves in a cylindrical or spherical enclosure (repeating aggregation and divergence at the center O), and (b) and (c) are cylindrical shapes. It is the figure which showed a mode that the acoustic port arrange | positioned on the center axis | shaft of a housing, or the center of a spherical housing, or its opening part prevented aggregation of a standing wave. (A) shows that a plurality of and even number of equivalent speaker units are arranged on the surface of a cylindrical casing or a spherical casing in a point-symmetric manner at one point on the cylindrical central axis of the cylindrical casing or the center O of the spherical casing. FIG. 6B is a diagram showing a state in which sound waves (indicated by broken-line arrows in the figure) radiated from each speaker unit reach the opposite speaker unit in the housing of the driving spherical speaker system, (b) (C) is a figure showing a mode that the acoustic port arrange | positioned on the center axis | shaft or center of a housing acts as an obstruction which prevents the arrival. FIG. 3 is a diagram in which a spherical loudspeaker system prototyped with a configuration that implements the aspect of the invention according to the present invention is actually auditioned, and the output frequency characteristics by auditory sensation are graphed and represented by a solid line. For comparison, the actual data of a single speaker unit is represented by a broken line, and the output frequency characteristics by simulation when eight speaker units are attached to a sealed rectangular housing having the same volume as the prototype, are represented by a one-dot chain line. A two-dot chain line represents the output frequency characteristics by simulation when eight speaker units are attached to a phase-inverted rectangular housing having the same volume as the prototype (the position of the opening inside the housing of the bass reflex duct is arbitrary). It is a figure showing the operation principle of the “pseudo respiratory sphere method” that has a plurality of identical speaker units on the surface of one spherical enclosure and expects an effect similar to a respiratory sphere by driving in phase. (A) represents a sound field (indicated by a broken line) when in-phase output is performed from two sound sources A and B, and (b) represents the same circumference around point O with three sound sources A, B, and C (b). The sound field (indicated by a broken line) when randomly placed on each sound source and output in-phase from each sound source is indicated by a broken line, and (c) indicates three sound sources A, B, and C, and a point O. On the same circumference as the center (indicated by a one-dot chain line), the sound fields are arranged at equal intervals (equal) at an angle of 120 degrees from the center O and output in phase from each sound source (indicated by a broken line). FIG. However, the output directivity characteristic of each sound source is flat, that is, a beautiful spherical wave is output. It is the graph which represented the output waveform from each sound source of A * B * C in FIG. 8, and the arrival waveform in each point of P1-P10 over time. However, attenuation due to propagation and diffusion in the air shall be ignored.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 2a, 2b, 2c, 2d Speaker unit 3a, 3b, 3c, 3d Back wave sound pressure 4 Standing wave 5a, 5b, 5c, 5d Direct back wave 6 Reflected wave from body wall 9 Acoustic port 10 Speaker system 11 Spherical shape Enclosure 12 Enclosure space 13 Speaker unit 14 Diaphragm 14a Diaphragm center 15 Acoustic port 16 Acoustic port casing inner opening (entrance)
17 Sound port housing outer opening (exit)
18 Center of housing O Center of circle or sphere A, B, C Sound source SP1, SP2, SP3 Speaker unit

Claims (4)

A plurality of speaker units that share the internal space of the casing as a common back cavity are provided on the surface of one casing, and all of the speaker units are radiated directly from the back of each diaphragm of the speaker unit. A speaker system that is arranged on the surface of the housing and has the same phase drive with a positional relationship where a point P0 where the sum of vectors of acoustic energy is always zero exists, and the distances from the diaphragm centers of all the speaker units A speaker system comprising a cylindrical acoustic port in which a housing inner opening (entrance) is disposed at the point P0 which is also equal to each other, and a housing outer opening (exit) is disposed on the surface of the housing. The casing is spherical or cylindrical, and the shape of the acoustic port does not have any plane parallel to any of the inner wall surfaces of the casing and is parallel to any diaphragm back of the speaker unit. The speaker system according to claim 1, wherein the speaker system has a shape having no surface. The speaker system according to claim 1, wherein the casing is cylindrical, and the acoustic port is disposed on a central axis of the casing along the central axis. In the speaker unit and another speaker unit having a positional relationship opposite to each other across the speaker unit and the speaker unit, the size of the opening (entrance) inside the housing of the acoustic port is determined by the diaphragm of the speaker unit. The speaker system according to claim 1, wherein the speaker system has a size equal to or larger than a size of an image that is projected right behind.