WO2011039842A1 - Sound reproducing device - Google Patents

Abstract

A sound reproducing device is provided with a housing (6), a first speaker unit (4) provided in the housing (6) and that emits a first sound wave, a second speaker unit (5) that has the same sound reproduction characteristics as the first speaker unit (4), that is provided in the housing (6), and that emits a second sound wave for reducing the sound pressure of the vibration noise generated by housing (6) being vibrated along with the vibration of the first speaker unit (4), an opening (10) formed through the housing (6) for emitting the first and second sound waves to outside of the housing (6), and an anchoring unit (7) that anchors the first and second speaker units (4, 5) to the housing (6). The opening (10) is formed to satisfy D < c/2f, where the width in the longitudinal direction is D, the frequency of the vibration noise for which sound pressure is to be reduced is f, and the speed of sound is c.

Description

Sound reproduction device

The present invention relates to a sound reproducing device in a thin display device such as a liquid crystal television.

In recent years, thin display devices such as liquid crystal televisions equipped with a sound reproducing device have been made thinner and thinner as the housing has become lighter and thinner. In such a thin display device, due to insufficient rigidity of the housing and the support portion, the housing is vibrated with sound reproduction by the speaker, and unnecessary vibration sound is generated from the housing. Moreover, the vibration of the housing deteriorates the sound reproduction performance of the speaker. In a thin AV device or a small AV device such as a thin display device, an unnecessary vibration sound is generated from the housing, and thus it is difficult to reproduce the original sound faithfully.

A plurality of sound faithful reproduction techniques for shaping an impulse response waveform in the time domain are disclosed as methods for realizing faithful original sound reproduction. For example, Patent Documents 1 to 3 disclose a speaker device that suppresses vibration by increasing the housing and support rigidity. Patent Document 4 discloses a speaker device that actively controls an auxiliary speaker provided to a main speaker to cancel unwanted sounds such as a case diffracted sound and a case vibration sound generated by a case vibration. Yes. These relate to an algorithm of a technique for improving a time domain impulse response waveform to one pulse.

On the other hand, there are, for example, a double speaker driving method and a double voice coil method as acoustic correction technology by digital control using an auxiliary speaker. In the double speaker drive system, two speakers are mounted inside the enclosure, and the back pressure of the main speaker is removed by controlling the two speakers in the same phase, thereby improving the characteristics of the minimum resonance frequency even in a small volume. . In the double voice coil system, the output impedance of the drive amplifier is improved by flattening the electric impedances near the two lowest resonance frequencies by interference (see, for example, Patent Document 5).

JP 2001-78285 A JP 2002-152848 A Japanese Patent Laid-Open No. 2005-12568 JP 2008-245159 A JP 11-146479 A

When the above speaker device is mounted on a thin AV device such as a thin display device, there is a problem in installation space, and further, the vibration from the auxiliary speaker propagates to the main speaker and causes deterioration in sound quality. There's a problem. Speakers employed in thin display devices and the like are generally elliptical speakers. When an elliptical speaker is also used as an auxiliary speaker and placed adjacent to the main speaker, the sound source centers of the main speaker and the auxiliary speaker are separated from each other. It becomes. As a result, interference non-uniformity occurs in places other than the front of the speaker, and the area where the sound quality is improved becomes narrower. Therefore, the sound reproducing device is required to be able to be disposed in a small space and to reduce unnecessary vibration sound generated from the thin housing.

The present invention has been made in order to solve the above-described problems, and the object thereof is to improve the sound quality by suppressing unnecessary vibration sound generated from a thin casing that can be arranged in a small space. An object of the present invention is to provide a sound reproducing apparatus capable of

According to the sound reproducing device of the present invention,
A housing,
A first speaker unit that is provided in the housing and emits a first sound wave;
A second speaker unit that has the same sound reproduction characteristics as the first speaker unit, is provided in the housing, and emits a second sound wave;
An opening that penetrates through the housing and radiates the first and second sound waves to the outside of the housing;
A fixing portion for fixing the first and second speaker units to the housing;
Comprising
The width D in the longitudinal direction of the opening satisfies D <c / 2f where f is the frequency of the vibration sound to be reduced in sound pressure and c is the sound speed.

According to the sound reproducing device of the present invention, it can be arranged in a small space, and the sound quality can be improved.

It is a front view which shows roughly an example of the thin display apparatus provided with the sound reproduction apparatus which concerns on this invention. 1B is a side sectional view schematically showing the arrangement of speakers in the thin display device shown in FIG. 1A. FIG. 1 is a cross-sectional view schematically showing a sound reproduction device according to a first embodiment. It is sectional drawing which follows the II line shown to FIG. 2A. FIG. 2B is a sectional view taken along line II-II shown in FIG. 2A. It is the top view which looked at the sound reproduction device shown in Drawing 2A from the bottom. It is a schematic diagram which shows the distance between the sound source centers of two speaker units. It is a schematic diagram which shows the sound source center of an elliptic speaker. It is a schematic diagram which shows the virtual sound source center in this Embodiment. It is a schematic diagram which shows the positional relationship of a 1st sound source, a 2nd sound source, and a listening point. It is a graph which shows the sound pressure level in the listening point shown in FIG. It is a schematic diagram which shows the difference of the distance from the viewing-and-listening position of a thin display apparatus to the 1st and 2nd speaker unit. It is a schematic diagram which shows the positional relationship of the sound source center of a 1st and 2nd speaker unit, and the center of an opening part. It is a graph which shows the relationship between an amplitude ratio and a sound pressure level. It is a front view which shows roughly the other example of a thin display apparatus provided with the sound reproduction apparatus which concerns on this invention. It is a sectional side view which shows schematic structure of the sound reproduction apparatus which concerns on 2nd Embodiment. It is sectional drawing which shows schematic structure of the sound reproduction apparatus which concerns on 3rd Embodiment. FIG. 13B is a sectional view taken along line III-III shown in FIG. 13A. It is sectional drawing which follows the VI-VI line shown to FIG. 13A. It is a front view which shows the external appearance of the sound reproduction apparatus shown to FIG. 13A. It is a sectional side view which shows the example in which a sound-absorbing material is provided in order to reduce the resonance in a housing | casing. It is a sectional side view which shows the example in which a conduit | pipe part is provided in order to reduce the resonance in a housing | casing. It is a sectional side view which shows schematic structure of the sound reproduction apparatus which concerns on 4th Embodiment. It is a sectional side view which shows schematic structure of the sound reproduction apparatus which concerns on 5th Embodiment. It is a front view which shows typically the structure of the speaker unit in the sound reproduction apparatus shown by FIG. It is a sectional side view which shows schematic structure of the sound reproduction apparatus which concerns on the modification of 5th Embodiment.

Hereinafter, the sound reproducing device according to the embodiment of the present invention will be described with reference to the drawings as necessary.

(First embodiment)
FIG. 1A is a front view schematically showing an appearance of a thin display device 10 including the sound reproducing device according to the first embodiment of the present invention, and FIG. 1B is an arrangement of speaker devices 24 in the thin display device 20. FIG. As shown in FIG. 1A, the thin display device 20 includes a housing 21 and a stand 22 that supports the housing 21, and a display panel 23 that displays an image is provided on the front surface of the housing 21. . As shown in FIG. 1B, a pair of speaker devices 24 are arranged below the display panel 23 so as to output sound toward the bottom of the housing 21. Openings are provided at positions corresponding to the speaker devices 24 at the bottom of the housing 21, and sound waves radiated from the speaker devices 24 are led out of the housing 21 through the openings. Since the casing 21 defines the outer shape of the thin display device 20, it is formed in a box shape with a small depth and a thin space inside. In the description of the embodiment, when the display panel 23 is viewed from the front, the horizontal scanning line direction is assumed to be left and right, and the vertical direction is assumed to be up and down.

The thin display device 20 includes a tuner (not shown) that receives and demodulates a television broadcast signal, and an acoustic signal is generated by an acoustic signal generator (not shown) according to the demodulated signal. This acoustic signal is amplified by an amplifier and input to each speaker device 24, and the acoustic signal is converted into sound by each speaker device 24.

FIG. 2A shows a schematic configuration of the sound reproducing device according to the first embodiment. 2B is a sectional view taken along line II shown in FIG. 2A, FIG. 2C is a sectional view taken along line II-II shown in FIG. 2A, and FIG. 2D is shown in FIG. 2A. It is a top view which shows the sound reproducing device seen from the direction of arrow A. The sound reproducing device shown in FIG. 2A corresponds to one of the pair of speaker devices 24 included in the thin display device 10 shown in FIGS. 1A and 1B. 2A to 2D shows a part of the housing 21 shown in FIG. 1A. As shown in FIG. 2A, the sound reproducing device includes a speaker diaphragm 1, first and second speaker units 4 and 5 each having a support portion 2 that supports the speaker diaphragm 1 and a voice coil 3. Since the casing 6 has a small depth, the first and second speaker units 4 and 5 employ elliptical speakers in which the speaker diaphragm 1 is formed in a substantially elliptical shape, and the first and second speakers. The units 4 and 5 are arranged in parallel along the longitudinal direction of each speaker diaphragm 1.

In various embodiments, the first and second speaker units 4, 5 have substantially the same configuration as each other, as shown in FIG. 2A, i.e., the same component, for example, a speaker diaphragm. The support portion and the voice coil are provided so as to have substantially the same outer dimensions.

The first speaker unit 4 functions as a main sound source speaker to which an acoustic signal generated from the television broadcast signal as described above is input. The second speaker unit 5 is for canceling unnecessary sound such as casing vibration sound other than the original sound included in the acoustic signal output from the first speaker unit 4 caused by insufficient rigidity of the casing 6 and the support portion 2. The sound wave is controlled so as to emit a sound wave having a phase opposite to that of the unnecessary sound. That is, the second speaker unit 5 outputs a control sound that cancels sounds other than the original sound output from the first speaker unit 4 according to the acoustic signal. In this specification, the unnecessary sound includes components other than the original sound according to the acoustic signal output from the first speaker unit 4, housing diffracted sound of the radiated sound radiated from the first speaker unit 4, It includes a case vibration sound generated by the case 6 being vibrated by the vibration of the speaker unit 4. Such unnecessary sound interferes with the control sound from the second speaker unit 5 to reduce the sound pressure. In the following description, the first speaker unit indicates a speaker for sound reproduction, and the second speaker unit indicates a control speaker.

The speaker support portion 2 of each of the first and second speaker units 5 is bonded and fixed to the speaker fixing portion 7, the speaker fixing portion 7 is fixed to the housing 6, and the first and second speaker units 5 are connected to the housing. It is fixed to the body 6. As shown in FIGS. 2A and 2B, the speaker fixing unit 7 is a rubber material, a resin material, or the like in order to suppress the vibration of the second speaker unit 5 from being transmitted to the first speaker unit 4 and the housing 6. The first speaker unit 4 is fixed to and supported by the speaker fixing portion 7 and the housing 6 via the buffer material 8. In general, control speakers used to improve the sound field and sound quality are premised on the absence of vibration radiated sound due to their own vibration, and air propagation consisting of direct sound and reflected diffraction sound that propagates in space. Only sound is used as an additional sound source. Therefore, in the present embodiment, the speaker fixing unit 7 to which the second speaker unit 5 for control is fixed prevents the vibration of the second speaker unit 5 from being transmitted to the housing 6 and the first speaker unit 4. Further, the housing 6 and the first speaker unit 4 are coupled to each other through a buffer material 8.

In addition, it is preferable that the buffer material 8 is provided also between the speaker fixing | fixed part 7 and the housing | casing 6 to which the 1st speaker unit 4 is fixed. However, when it is difficult to provide the buffer material 8 between the speaker fixing portion 7 to which the first speaker unit 4 is fixed and the housing 6 due to the limited volume, only the second speaker unit 5 has the buffer material. 8 may be supported and fixed. As described below, the sound pressure can be reduced by the control sound from the second speaker unit 5 such as a case vibration sound caused by the vibration of the first speaker unit 4. Because.

The housing 6 shown in FIG. 2A is formed so as to cover the first and second speaker units 5, and a tension adjusting unit is provided at a position facing the speaker diaphragm 1 of the first and second speaker units 5. 9 is fixed to the housing 6. The internal space of the housing 6 is determined by the housing 6 and the tension adjusting unit 9. As shown in FIGS. 2C and 2D, the tension adjusting unit 9 is located at a position facing the speaker diaphragm 1 of the first speaker unit 4 and has a substantially rectangular opening near the front surface of the thin display device 10. 10 is provided. Sound waves radiated from the first and second speaker units 4 and 5 are guided to the outside of the housing 6 through the opening 10 as indicated by arrows in FIG. 2C.

In the present embodiment, the space between the speaker vibration surface and the tension adjustment unit 9 is adjusted by adjusting the distance between the speaker vibration surface (that is, the speaker diaphragm 1) and the tension adjustment unit 9 and the position of the opening 10. Therefore, the system resonance frequency can be easily changed at the design stage. The tension adjusting unit 9 is formed of a material such as ABS resin, vinyl chloride, polycarbonate, urethane rubber, for example.

Note that the shape of the opening 10 is not limited to a rectangular shape, and may be a slit shape, an elliptical shape, or the like.

When the first and second speaker units 4, 5 are arranged in parallel along the longitudinal direction of the speaker diaphragm 1, as shown in FIG. 3, the sound sources of the first and second speaker units 4, 5 The distance d between the centers 15 and 16 is 15 cm or more. As a result, interference unevenness occurs in places other than the front surfaces of the first and second speaker units 4 and 5. More specifically, when the first and second speaker units 4 and 5 are simply arranged in parallel, the synthesized sound wave from the two speaker units 4 and 5 is radiated as one point, line or surface radiation. Accordingly, the spatial sound pressure interference accuracy between the two, which is a necessary condition for improving the sound quality, is uneven, and the control area by the control sound from the second speaker unit 5 is narrowed. Here, as described in “Speaker & Enclosure Encyclopedia (Seibundo Shinko), 1999”, the sound source center of each speaker unit is as shown in FIG. It is substantially equivalent to the center 18 of the diaphragm 1). In the present embodiment, the opening 10 is provided in the tension adjusting unit 9 used for adjusting the system resonance frequency of the speaker, so that the first and second speaker units 4, 5 is emitted from the virtual sound source center 17 in the opening 10 toward the outside of the housing 6. Thereby, the radiation characteristic of the synthesized sound of the first and second speaker units 4 and 5 can be improved to one line, point, and surface radiation.

Further, since the opening 10 is disposed at a position facing the first speaker unit 4, the sound emitted from the first speaker unit 4 for sound reproduction is not reduced in sound pressure, and the outside of the housing 6. To be derived. In addition, since the surface of the second speaker unit 5 facing the vibration surface of the speaker is closed by the tension adjusting unit 9, the radiated sound from the second speaker unit 5 is not only reduced in sound pressure but also reflected sound. In addition, the diffracted sound is also strongly superimposed. However, the radiated sound from the second speaker unit 5 can be effectively used as a control sound wave as described above. As a result, the controlled synthetic sound wave radiated from the opening 10 becomes an acoustic wave with good sound quality.

The first and second speaker units 4 and 5 are not limited to the same speaker unit as shown in FIG. 2A, and may have similar sound reproduction characteristics, for example, frequency characteristics. Speaker units having different configurations may be used.

Next, by radiating the synthesized sound from the first and second speaker units 4 and 5 through the opening 10 formed in the tension adjusting unit 9, the radiation equivalent to the radiation characteristic of the single speaker unit is emitted. A method of determining the longitudinal width of the opening 10 and the position of the opening 10 will be described so that the characteristics can be maintained.

As shown in FIG. 6, the radiated sound (corresponding to unnecessary sound) generated from the first sound source 51 is generated by generating a control sound having a phase opposite to that of the radiated sound from the second sound source 52. Consider the case of cancellation at 50. In this case, the sound pressure level SPL (sound pressure level) at the listening point 50 is generated by the amplitude q1 of the radiated sound generated by the first sound source 51 and the second sound source 52 as shown in the following formula 1. It is represented by the amplitude q2 of the control sound wave, the distance L between the first sound source 51 and the listening point 50, the distance L + Δr between the second sound source 52 and the listening point 50, and the wave number k of the sound wave. In the following equation, P1 represents the sound pressure of the radiated sound at the listening point 50, P2 represents the sound pressure of the control sound at the listening point 50, θ1 represents the phase of the radiated sound, and j represents an imaginary number.

Here, Δr indicates the difference between the distance between the second sound source 52 and the listening point 50 and the distance between the first sound source 51 and the listening point 50.

FIG. 7 shows the sound pressure level SPL calculated from Equation 1 as a function of the amplitude ratio of the sound waves from the first and second sound sources 51 and 52. FIG. 7 confirms that the sound pressure level SPL decreases as the amplitude ratio (q2 / q1) approaches 1, and that the sound pressure level SPL decreases as the path difference Δr decreases. The graph of FIG. 7 shows the calculation result when the frequency is 125 Hz, but the sound pressure level SPL shows the same tendency even if the frequency is changed. Here, a relationship of f = ck / 2π is established among the frequency f, the wave number k, and the sound speed c.

Thus, when the radiated sound radiated from the first sound source 51 is canceled by the control sound radiated from the second sound source 52, the amplitude of the radiated sound and the control sound is adjusted to be the same, and the listening point 50 It is desirable to arrange the first and second sound sources 51 and 52 so as to be equidistant.

As described above, when elliptical speakers generally used in a thin display device are arranged in parallel along the longitudinal direction of the speaker diaphragm 1, the sound source centers of the two speakers are separated from each other by about 15 cm or more. In general, as shown in FIG. 8, a viewer views a television broadcast at a viewing position 50 that is several meters away from the front of the thin display device 53. FIG. 8 shows an example in which the speakers 54 and 55 are arranged toward the front surface of the thin display device 53. In such a case, since the path difference Δr does not approach zero, the sound pressure reduction effect by the control sound from the second sound source 52 is reduced at the viewing position 50. Such a decrease in the sound pressure reduction effect becomes more significant as the frequency increases.

In the present embodiment, the first and second speaker units 4 and 5 (corresponding to the first and second sound sources 51 and 52, respectively) are provided in the housing 6, and the first and second speakers are provided. The synthesized sound waves of the units 4 and 5 are radiated to the outside of the housing 6 through the opening 10 that opens through the housing 6. In this case, even if the distance d between the sound source centers of the first and second speaker units 4 and 5 is increased, the same radiation characteristics as when only a single speaker is provided are maintained. However, when the width D in the longitudinal direction of the opening 10 is equal to or exceeds the width of the first and second speaker units 4 and 5, such radiation characteristics cannot be maintained. The width D in the longitudinal direction of the opening 10 is defined by the frequency f and the sound speed c of the unnecessary sound to be controlled as shown in the following formula 2. When the condition of Formula 2 is not satisfied, a plurality of maximum sound pressure points and minimum points are generated in the opening 10, and one virtual sound source center in the opening 10 cannot be realized.

D <C / 2f (m) Formula 2
When the sound reproducing device according to the present embodiment is applied to the thin display device 20 as shown in FIG. 1A, for example, the frequency f of the unwanted sound to be controlled is 10 kHz or less, and the longitudinal direction of the opening 10 The width D is less than 1.7 cm. Here, the sound speed c is set to 340 m / s.

FIG. 9 shows an arrangement of each component of the sound reproducing device on a plane including the sound source centers of the first and second speaker units 4 and 5. In the plan view shown in FIG. 9, the width of the housing 6 in which the first and second speaker units 4 and 5 are stored is L (m), and the first sound source center and the housing of the first speaker unit 4 are accommodated. The distance from the body 6 is r1 (m), the distance between the second sound source center of the second speaker unit 5 and the housing 6 is r2 (m), and the distance between the first and second sound source centers is d ( m). Further, the distances from the perpendicular to the straight line passing through the center of the opening 10 and connecting the first and second sound source centers to the sound source centers of the first and second speaker units 4 and 5 are d1 (m) and d2 ( m). Furthermore, the width in the longitudinal direction of the opening 10 is D, and the distances from both ends of the opening 10 to the housing 6 are L1 (m) and L2 (m), respectively. The distance here refers to the distance along the longitudinal direction of the speaker diaphragm 1. When the control sound having the opposite phase and the same amplitude is output from the second sound source to reduce the sound pressure at the center of the opening 10 with respect to the unnecessary sound output from the first sound source, The sound pressure level SPL is represented by the following mathematical formula 3, where q1 = q2, L = d1, and Δr = d2-d1 in the mathematical formula 1.

In Formula 3, when d1 = d2, the inside of the absolute value is zero, sound pressure interference occurs completely at the center of the opening 10, and the sound pressure level SPL is theoretically minus infinity. Therefore, it is more effective for suppressing unnecessary sound to arrange the center of the opening 10 at the same distance from the sound source centers of the two sound sources. However, as apparent from the graph of FIG. 7, even when the path difference Δr can be made close to zero, the amplitude ratio of the sound pressures of the sound waves that reach from the two sound sources transmitted to the opening 10 is the same. If not, the sound pressure reduction effect is significantly reduced.

For example, for the purpose of reducing unnecessary sound by about 10 dB, it can be seen from the graph of FIG. 10 that the path difference Δr may be about 15 cm as long as the input amplitudes of the two sound sources are the same. That is, the condition of d2 = d1 + 0.15 is a condition. Further, since L, r1, r2, and d are determined by the relationship between the shape of the first and second speaker units 4 and 5 and the space in the housing 6, d1 is determined. The long side length D of 10 is determined. Further, L1 is obtained from d1 and r1, and L2 is obtained from d2 and r2.

In this way, by defining the longitudinal width D of the opening 10 so as to satisfy Formula 2, the synthesized sound of the sounds output from the two speaker units 4 and 5 in the housing 6 can be A virtual sound source center can be realized at the center. Furthermore, since the unnecessary sound can be reduced in interference at the opening 10, unnecessary sound radiated to the viewing position via the opening 10 can be reduced.

As described above, in the sound reproduction device according to the first embodiment, the sound reproduction speaker unit 4 and the control speaker unit 5 are arranged in parallel in the housing 6, and the sound reproduction speaker unit 4 and the control are provided. The synthesized sound wave from the speaker unit 5 is radiated to the outside of the housing 6 through the opening 10. The controlled synthesized sound wave radiated through the opening 10 has a radiation characteristic equivalent to that of a single speaker unit, and unnecessary sounds other than the original sound generated from the sound reproducing speaker unit 4 are reduced. ing. Therefore, in the sound reproducing device of the present embodiment, the sound quality can be improved even when mounted in the thin housing 6.

(Second Embodiment)
With reference to FIG.11 and FIG.12, the sound reproduction apparatus which concerns on 2nd Embodiment is demonstrated. 11 and 12, the same reference numerals as those shown in FIGS. 1 to 2D are attached to the same portions and the same portions, and the description thereof is omitted.

FIG. 11 shows the appearance of the thin display device 30 including the sound reproducing device according to the second embodiment. In the thin display device 30 shown in FIG. 11, unlike the thin display device 20 shown in FIGS. 1A and 1B, a sound emitting opening 10 is provided on the front surface of the housing 21.

FIG. 12 is a side sectional view showing a schematic configuration of the sound reproducing device according to the second embodiment. In the second embodiment, the first and second speaker units 4 and 5 are arranged vertically in the housing 6 so as to face each other as shown in FIG. The first and second speaker units 4 and 5 are fixed to the housing 6 via buffer materials 8 respectively. More specifically, in each of the speaker units 4 and 5, the speaker support portion 2 is fixed to the speaker fixing portion 7, and the speaker fixing portion 7 is fixed to the housing 6 through the buffer material 8. Such a configuration in which the first and second speaker units 4 and 5 are arranged vertically is possible when a certain amount of volume is secured in the housing 6.

Also in the second embodiment, the first and second speaker units 4 and 5 are elliptical speakers, and the longitudinal direction of the speaker diaphragm 1 of the first and second speaker units 4 and 5 in FIG. Corresponds to the direction perpendicular to the page. The opening 10 is formed on the front surface of the housing 6 at a position facing the space between the first and second speaker units 4 and 5. The opening 10 is formed in a substantially rectangular shape that is elongated along the longitudinal direction of the speaker diaphragm 1, and the width in the longitudinal direction is determined so as to satisfy Formula 2. By synthesizing the synthesized sound of the sounds radiated from the first and second speaker units 4 and 5 to the outside of the housing 6 through the opening 10, the synthesized sound whose sound quality is improved is obtained by a single speaker. An acoustic characteristic equivalent to the acoustic characteristic can be provided.

Further, in the housing 6, a tension adjusting unit 9 is provided with the first and second speaker units 4, 5 so as to guide sound waves radiated from the first and second speaker units 4, 5 to the opening 10. It is arrange | positioned diagonally with respect to the speaker vibration surface. By installing the tension adjusting unit 9, the air spring acting on the speaker diaphragm 1 of the first and second speaker units 4 and 5 can be changed, and the system resonance frequency can be easily changed at the design stage. .

When the first and second speaker units 4 and 5 are arranged so as to face each other as shown in FIG. 12, the distance between the sound source centers of the first and second speaker units 4 and 5 becomes shorter. The distances from the sound source centers of the first and second speaker units 4 and 5 to the center of the opening 10 are equal. Therefore, components other than the original sound generated from the first speaker unit 4 can be greatly reduced, and the sound quality of the sound radiated from the opening 10 can be improved.

In the example shown in FIG. 12, the first speaker unit 4 is disposed above the second speaker unit 5, the first speaker unit 4 is provided downward, and the second speaker unit 5 is provided upward. However, the present invention is not limited to this, and the arrangement of the first and second speaker units 4 and 5 may be interchanged.

(Third embodiment)
With reference to FIGS. 13A to 13D, the sound reproducing device according to the third embodiment will be described. 13A to 13D, the same reference numerals as those shown in FIGS. 2A to 2D are attached to the same portions and the same portions, and the description thereof is omitted. The third embodiment is applied to a thin display device 30 in which an opening 10 for sound emission is provided on the front surface of a housing 21 as shown in FIG.

FIG. 13A shows a schematic configuration of the sound reproducing device according to the third embodiment. 13B is a cross-sectional view taken along the line III-III, FIG. 13C is a cross-sectional view taken along the line IV-IV, and FIG. 13D is a front view showing the appearance of the sound reproducing device. In the third embodiment, the first and second speaker units 4 and 5 are arranged in the same manner as in the first embodiment. In the third embodiment, the first and second speaker units 4 and 5 are covered with the housing 6 as shown in FIGS. 13A to 13D, and the first and second speaker units 4 are covered. The opening 10 for radiating sound waves from the outside of the housing 6 to the outside of the housing 6 is the front surface of the housing 6 and the first speaker unit 4 side below the first and second speaker units 4 and 5. Is provided. The conduit portion 11 that is a part of the housing 6 positioned below the speaker diaphragm 1 functions as a conduit for guiding sound waves radiated from the first and second speaker units 4 and 5 to the opening 10. .

The third embodiment has the same advantages as those of the first embodiment. Further, since the opening 10 is provided in the front surface of the housing 6, the first and second speaker units 4, 5 are provided. It is possible to prevent the synthesized sound from the sound pressure from being lowered before reaching the viewing position.

In the space defined by the first and second speaker units 4 and 5 and the conduit portion 11, a sound absorbing material 13 may be provided as shown in FIG. 14A. Further, as shown in FIG. 14B, the speaker diaphragms of the first and second speaker units 4, 5 so that the radiated sound from the first and second speaker units 4, 5 is guided to the opening 10. The conduit portion 14 may be formed to be inclined with respect to 1. In these cases, resonance in the space defined by the conduit portion 11 and the first and second speaker units can be suppressed.

(Fourth embodiment)
With reference to FIG. 15, a sound reproduction device according to the fourth embodiment will be described.

FIG. 15 is a side sectional view showing a schematic configuration of the sound reproducing device according to the fourth embodiment. In the fourth embodiment, as shown in FIG. 15, the second speaker unit 5 is arranged in series behind the first speaker unit 4 in the housing 6. The second speaker unit 5 for control is fixed to the housing 6 by connecting the speaker fixing portion 7 and the housing 6 via the cushioning material 8, whereas the first speaker unit 5 for sound reproduction is used. The speaker unit 4 is supported and fixed to the casing 6 by connecting the speaker fixing section 7 and the casing 6 by the speaker support section 12 so as not to block sound waves from the second speaker unit 5. When the first speaker unit 4 is fixed to the housing 6 via the buffer material 8, the control sound from the second speaker unit 5 is blocked by the buffer material 8, and as a result, the housing 6 vibration sound It becomes impossible to reduce the sound pressure of the unnecessary sound such as the control sound from the second speaker unit 5.

In the fourth embodiment, since the sound source centers of the first and second speaker units 4 and 5 are arranged relatively close to each other, unnecessary sound such as housing vibration sound is efficiently reduced. be able to.

(Fifth embodiment)
With reference to FIG.16 and FIG.17, the sound reproduction apparatus which concerns on 5th Embodiment is demonstrated.

FIG. 16 is a cross-sectional view showing a schematic configuration of the sound reproducing device according to the fifth embodiment, and FIG. 17 is a plan view of the speaker unit as viewed from the front. In the fifth embodiment, the first and second speaker units 4 and 5 are provided sideways so as to radiate sound waves toward the front surface of the housing 6, and the short side of the elliptical speaker diaphragm 1. It is arranged up and down along the direction. The first and second speaker units 4, 5 are fixed to the housing 6 by the speaker fixing portion 7, and the first and second speaker units 4, 5 are interposed between the speaker fixing portion 7 and the housing 6. A buffer material 8 is provided for suppressing the transmission of the vibration. Further, the speaker fixing part 7 to which the first speaker unit 4 is fixed and the speaker fixing part 7 to which the second speaker unit 5 is fixed are connected via a buffer material 8.

The opening 10 for radiating the synthesized sound waves from the first and second speaker units 4 and 5 is provided on the front surface of the housing 6 at a position facing the first speaker unit 4. The control sound wave from the second speaker unit 5 is guided to the opening 10 by the conduit portion 11 and can interfere with the sound wave from the first speaker unit 4 to reduce unnecessary sound.

In the fifth embodiment, each of the speaker units 4 and 5 has a unit structure that is actually employed in many thin display devices as shown in FIG. Each speaker unit 4, 5 includes a speaker diaphragm 1, a support portion 2 that supports the speaker diaphragm 1, and a voice coil 3, and as shown in FIG. 17, a speaker fixing portion that faces the speaker diaphragm 1. 7 is provided, and a speaker opening 27 and a tension adjusting unit 26 are provided at a position of the speaker fixing unit 7 facing the speaker diaphragm 1. Each speaker unit 4, 5 includes a buffer material 8 that prevents vibration propagation to the housing 6.

In the sound reproducing device according to the fifth embodiment, since the first and second speaker units 4 and 5 are both fixed to the housing 6 via the cushioning material 8, each speaker unit 4 and 5 Vibration propagating to the housing 6 is suppressed, and housing vibration noise is reduced. Further, since the synthesized sound wave from the first and second speaker units 4 and 5 is radiated from the single opening 10 to the outside of the housing 6, the radiation characteristic equivalent to that of a single speaker is maintained. Can do.

FIG. 18 shows a modification of the fifth embodiment. In the modification of the fifth embodiment, as shown in FIG. 18, the first speaker unit 4 is provided facing the front in the housing 6, and the second speaker unit 5 is the first speaker. The loudspeaker diaphragm 1 of the second loudspeaker unit 5 is directed downward, and the first loudspeaker unit 4 and the second loudspeaker unit 5 are arranged perpendicular to each other. . Also in this case, each speaker unit is fixed to the housing 6 via the buffer material 8.

As described above, in this embodiment, the sound reproducing apparatus can be configured using the existing speaker unit.

In the fifth embodiment and its modifications, the arrangement locations of the first and second speaker units 4 and 5 may be interchanged. For example, in the sound reproducing device shown in FIG. 16, the first speaker unit 4 may be disposed above the second speaker unit 5.

According to the embodiment described above, it can be arranged in a small volume in the thin housing 6, and unnecessary sound such as housing vibration sound generated from the housing 6 can be reduced to improve sound quality. It is possible to provide a sound reproducing device that can be used.

Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The sound reproducing apparatus according to the present invention is used for an apparatus that requires a speaker to be installed in a small volume. For example, it can be applied to a thin display device such as a liquid crystal television or to a small speaker.

DESCRIPTION OF SYMBOLS 1 ... Speaker diaphragm, 2 ... Support part, 3 ... Voice coil, 4 ... 1st speaker unit, 5 ... 2nd speaker unit, 6 ... Housing, 7 ... Speaker fixing | fixed part, 8 ... Buffer material, 9, DESCRIPTION OF SYMBOLS 11,26 ... Tension adjustment part, 10 ... Opening part, 11,14 ... Conduit part, 13 ... Sound-absorbing material, 20, 30 ... Thin display apparatus, 21 ... Housing | casing, 22 ... Stand, 23 ... Display panel, 24 ... Speaker apparatus

Claims (10)

A housing,
A first speaker unit provided in the housing and emitting a first sound wave;
A second speaker unit that has the same sound reproduction characteristics as the first speaker unit, is provided in the housing, and emits a second sound wave;
An opening that penetrates through the housing and radiates the first and second sound waves to the outside of the housing;
A fixing portion for fixing the first and second speaker units to the housing;
Comprising
The width D in the longitudinal direction of the opening is an acoustic reproduction device that satisfies D <c / 2f, where f is the frequency of the vibration sound to be reduced and the speed of sound is c. The sound reproducing apparatus according to claim 1, wherein the first and second speaker units include first and second speaker diaphragms having substantially elliptical shapes, respectively. The first and second speaker units are arranged in parallel along the longitudinal direction of the first and second speaker diaphragms,
The sound reproducing device according to claim 2, wherein the opening is provided to face the first speaker unit. The first and second speaker units are arranged to face each other,
The sound reproducing device according to claim 2, wherein the opening is provided facing a space defined by the first and second speaker units and the housing. The first and second speaker units are arranged in parallel along the longitudinal direction of the first and second speaker diaphragms,
The sound reproducing device according to claim 2, wherein the opening is provided on a surface of the casing perpendicular to the speaker diaphragm of each of the first and second speaker units. The sound reproducing apparatus according to claim 5, wherein the casing includes a conduit portion that guides the first and second sound waves to the opening. The sound reproducing device according to claim 1, wherein the second speaker unit is arranged behind the first speaker unit. The first and second speaker units are arranged in parallel along the short direction of the first and second speaker diaphragms,
The sound reproducing device according to claim 2, wherein the housing includes a waveguide that guides the first and second sound waves to the opening. The sound reproducing device according to claim 1, wherein the first and second speaker units are arranged orthogonal to each other. The sound reproduction device according to claim 1, wherein the second speaker unit is fixed to the housing via a buffer material for suppressing propagation of vibration.

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