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JPH0479500

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DESCRIPTION JPH0479500
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker system used as a surround speaker of an audio apparatus, and more particularly to a
narrow directivity speaker system. 2. Description of the Related Art In general, a surround
method is known as a method for creating a feeling of sound field resembling the acoustic
characteristics of a large hole, a small hole or the like in a sound field space such as a listening
room. In the surround system, in addition to front speakers (a pair of left and right) disposed on
the front of the listener, an effect speaker (sub-speaker) that emits reflected sound is used. In the
surround system, the presence of the speaker, ie, the sound coming from the speaker, produces a
rather negative effect, so it is necessary to devise that the sound source position, that is, the
position of the speaker is not felt by the listener. As a method for that purpose, there is a method
of making a speaker's presence thin by making a sound reflect on a wall surface around a listener
in a listening room. It is an effect speaker that is used to actively emit such a reflected sound. It is
more effective to reflect the radiation sound not only on one wall but also on all the walls
surrounding the listener. Furthermore, the longer the relative distance between the reflecting
wall and the effect speaker, the longer it will take for the reflected sound to reach the listener,
and thus it is more effective in that the effect speaker is felt to be located farther. On the other
hand, in order to simplify the configuration of the surround system, it is preferable that the
number of effect speakers be small. 11 to 17 show an example of a conventional effect speaker
system constituted by one speaker system. As shown in the plan view of FIG. 11, the front
speakers 101 and 102 are disposed in front of the listener 112 in the acoustic space 100, and
the effect speaker 103 is disposed at the upper rear of the listener 112. The sound radiation
direction of the effect speaker 103 is behind and to the left and right of the listener 112, and the
emitted sound wave is reflected on the inner wall surface of the acoustic space 100 to reach the
ear of the listener 112. In this manner, by using the reflected sound, it is possible to create an
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effect as if the imaginary sound source speakers 104.105.106 exist outside the acoustic space
100 as shown in the figure. 12 is an elevation view of FIG. As seen from FIG. 12, the effect
speaker 103 is suspended on the ceiling of the acoustic space 100, and the reflected sound from
the rear reaches the listener 112 through the illustrated path.
An example of a conventional effect speaker 03 is shown in FIG. The effect speaker 03 is
obtained by arranging the bass speaker unit 108. 109 outside and the treble speaker unit 110
111 inside the baffle surface of the enclosure 107 inline. Each of the bass speaker unit 108 and
the treble speaker unit 110, and the bass speaker unit 109 and the treble speaker unit 111 have
a proper division frequency (crossover frequency) f as shown in FIG. It is assigned. The
arrangement interval (center to center) D of the bass speaker unit 108 and the treble speaker
unit 109 is D??. ... given by (1). Here, ? 1 is the C wavelength of the division frequency f 1 and
is given by ? ?1 / C (2) C: sound velocity. On the other hand, the arrangement interval d of the
high sound speaker system 110 and the high sound speaker system 111 is given by d? (D / 4)
▒ 50% (3). According to the above effect speaker 03, narrow directivity is provided in the ?
direction (horizontal direction) shown in FIG. However, since the direction orthogonal to the ?
direction, that is, the vertical direction is determined by the directivity of the unit itself possessed
by each of the bass speaker system 108 to the treble speaker system 110, narrow directivity, in
particular if it is not nondirectional. It is not sex. The directivity characteristic of the effect
speaker 03 having such a narrow directivity in the ? direction is shown in FIG. As can be seen
from FIG. 15, .theta.-0 '(the on-axis sound pressure level) exhibits a flat characteristic, and the
sound pressure level decreases as .theta. = 60 DEG .theta.-90 DEG. FIG. 16 shows the structure of
the speaker system by simulation, and FIG. 17 shows the directivity characteristic which is the
simulation result. [Problems to be Solved by the Invention] The problems with the abovementioned conventional effect speaker 103 are, first, that the directivity required to effectively
exhibit the surround effect is not sufficient, and secondly, the external shape of the speaker
system Is a big point. That is, for the first point described above, it is desirable that the basic
performance that should originally be present as an effect speaker system is nondirectional in
the horizontal direction 360 ░, and narrow directional in the vertical direction (vertical
direction). Under these conditions, the speaker presence is reduced and the effective radiation of
the reflected wave is satisfied to improve the surround feeling.
However, in the conventional effect speaker 103 described above, the horizontal direction is
narrow directivity and the vertical direction is equivalent to a normal speaker, which is not
sufficient for the basic performance. The second point is a problem arising from the relation with
the height of the ceiling when assuming a general household and the relation with the usually
required miniaturization. Generally, the ceiling height is about 2.3 to 2.5 m, and as shown in FIG.
12, in the case where the effect speaker system is suspended from the ceiling, it is desirable that
the effect speaker system be as small as possible. However, in order to obtain a good surround
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feeling, it is necessary to extend the frequency characteristics to a low frequency range and to
make the directivity narrow. In order to obtain narrow directivity to the low frequency range, it is
necessary to lower the division frequency f 1 as shown in the above-mentioned equations (1) and
(2). To lower the division frequency f 2 means to increase the distance between the bass
loudspeakers 08 and the bass loudspeakers 109, and therefore the outer dimensions of the
enclosure 1 inevitably become large. An object of the present invention is to provide a speaker
system which can ensure a sufficient directivity for practical use and can be miniaturized. [Means
for Solving the Problems] In order to solve the above-mentioned problems, according to a first
aspect of the present invention, a set of bass speaker units to which reproduction frequency
bands are respectively assigned at predetermined division frequencies and A speaker unit for
high sound is attached to a support, and a reflecting plate extending forward in an acoustic
radiation direction of each speaker unit is provided on the high sound speaker unit side position
in the arrangement direction of the speaker units of the support. . A second invention according
to claim 5 has a pair of bass speaker units and a treble speaker unit to which reproduction
frequency bands are respectively assigned at predetermined division frequencies, and the sound
radiation direction forward of the bass speaker unit A reflector is disposed at a position facing
the diaphragm of the bass speaker unit and at a distance of about 1/2 the wavelength of the
division frequency between the bass speaker unit and the diaphragm of the bass speaker unit.
The high-pitched speaker unit is disposed between the reflection plate and the low-pitched
speaker unit in the same direction as the low-pitched speaker unit. [Action 1 According to the
first aspect of the invention, the sound radiation direction of the bass speaker unit and the treble
speaker unit at the side of the treble speaker unit in the arrangement direction of the bass
speaker unit and the treble speaker unit By extending the reflector forward, it acts in the same
way as a virtual sound source exists at the target position of the bass speaker unit and the treble
speaker unit at the boundary of the reflector by the mirror image principle, and has narrow
directivity. Can provide a speaker system.
According to the second aspect of the present invention, the horizontal direction 360 is obtained
by arranging the reflection plate so as to face the diaphragm of the bass speaker unit at the front
in the acoustic radiation direction of the bass speaker unit and the treble speaker unit. It provides
a speaker system with narrow directivity in the vertical direction with an omnidirectionality of
░░. Next, an embodiment of the present invention will be described with reference to the
drawings. First Embodiment FIGS. 1 to 7 show an embodiment (hereinafter referred to as a first
embodiment) according to the invention as set forth in the claims. In FIG. 1, on the baffle surface
of the enclosure 1 having an appropriate volume, the bass speaker unit 2 and the treble speaker
unit 3 are arranged in line so that the central axes thereof are on the same line. At the end of the
high sound speaker unit 3 side in the arrangement direction of the low sound speaker unit 2 and
the high sound speaker unit 3 in the enclosure 1, a reflection extending forward of the sound
emission direction of the low sound speaker unit 2 and high sound speaker unit 3 A plate 6 is
provided in a protruding manner. The central axis of the low frequency speaker unit 2 maintains
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a distance of D / 2 with the reflecting plate 6, and the high frequency speaker unit 3 has a
central axis of a distance of d / 2 with the reflecting plate 6. Each one is arranged to keep. The
reflecting plate 6 is usually rectangular, but a disc or the like can also be used. However, the
length of one side of the reflecting plate 6 is the wavelength ? of the division frequency f. It has
been experimentally confirmed that if the diameter is twice or more the diameter of, the
characteristic similar to that of the effect speaker 03 shown in FIG. 13 is obtained (see FIGS. 2 to
5). When a disk is used as the reflecting plate 6, the diameter L of the reflecting plate 6 is the
length of 2? described above. As described above, focusing on the symmetry of the speaker
arrangement of the effect speaker 103 shown in FIG. 13 and providing the reflection plate 6 at
the center line position, necessary narrow directivity can be reduced to 1/1 of the effect speaker
03. It can be realized with a size of 2 and a number of speaker units of 1/2. That is, due to the
presence of the reflecting plate 6, the virtual bass speaker unit 4 and the virtual treble speaker
unit 5 are present at symmetrical positions of the bass speaker unit 2 and the treble speaker unit
3 with the reflector 6 at the center. It is possible to carry out the equivalent operation. FIG. 2
shows a perspective view of the speaker system in the case where the reflecting plate 6 is a
square plate of 400 mm О 600 + nm dog pitch, and FIG. 3 shows the frequency characteristic of
the simulation result in that case.
As seen from FIG. 3, when the angle of the ? (horizontal) direction is sequentially changed and
observed from when the extending direction of the reflecting plate 6 is 0 ░ on the axis, the
sound pressure level drops in the high sound range Can be seen. This means that the directivity
is narrow in the ? direction. FIG. 4 shows a perspective view of a speaker system when the
reflector 6 is a square plate of 1000 + nm О 1000 mm in size, and FIG. 5 shows frequency
characteristics of simulation results in that case. As can be seen from FIG. 5, as the area of the
reflecting plate 6 is increased, the directivity change band shifts to the bass range. Similarly,
when the extension direction of the reflecting plate 6 is 0 ░ on the axis, when the angle in the ?
direction is sequentially changed and observed, the drop of the sound pressure level in the
middle range to the high range is remarkable. That is, the increase in the area of the reflection
plate 6 means that the band affected by the directivity shifts to the bass side and has narrow
directivity in the ? direction. 6 (front view) and 7 (side cross-sectional view) show examples
where the above speaker system is used as a speaker system of a television apparatus. As shown
in FIG. 6, the speaker system 8 is mounted such that the bass speaker unit 2 and the treble
speaker unit 3 are located at the back of the reflector 6 with the reflector 6 on the front side. . As
shown in more detail in FIG. 7, the speaker system 8 is mounted so as to be extractable with
pivoting forward. The cabinet 11 doubles as a base for the television set 7 and a horn-like baffle
plate is provided at the middle portion in the front-rear direction so as to divide the inside of the
cabinet 11 back and forth. The super low tone speaker unit 10 having the space on the rear side
as a pack cavity is attached to the baffle plate. Furthermore, the speaker system according to the
present embodiment is rotatably mounted in the space on the front side of the cabinet 11
partitioned by the baffle plate. In the speaker system, as shown in FIG. 7, the reflector 6 is
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located at the frontmost side, the enclosure 1 is provided on the back side, and the arrangement
direction of the bass speaker unit 2 and the treble speaker unit 3 is the cabinet 11. It is attached
along the longitudinal direction. A filter 12 is attached to the upper surface (the radiation
direction of the sound wave) of the bass speaker unit 2 and the treble speaker unit 3. The filter
12 is an auxiliary member for further narrowing the directivity of the bass speaker unit 2 and the
treble speaker unit 3 in the direction along the arrangement direction of the bass speaker unit 2
and the treble speaker unit 3, It does not affect the directivity in the left and right direction
toward the screen of the television device 7.
In the above configuration, when the speaker system is not in use, the speaker system is
accommodated in the cabinet 11 as shown by a broken line in FIG. In use, as indicated by a solid
line, it is locked at a predetermined rotational position by pulling it forward, and at that time, the
acoustic radiation direction is set in a direction toward the glass plate 9 disposed on the front of
the television device 7. When the low frequency speaker unit 2 and the high frequency speaker
unit 3 are driven in this state, the reproduced sound is reflected by the glass plate 9 and reaches
the viewer. Also in such usage, a virtual sound source exists at the symmetrical position of the
reflector 6 by the mirror image principle, and narrow directivity can be obtained. In the above
description, the reflecting plate 6 is provided alone, but as can be understood from FIGS. 4 and 5,
the directivity, the frequency band affecting the directivity and the length of one side of the
reflecting plate 6 Depending on (or area), it is also possible to use plates (not the inner wall of the
acoustic space). Second Embodiment FIGS. 8 to 10 show an embodiment according to the fifth
aspect of the present invention (hereinafter referred to as the second embodiment). The feature
of this embodiment is that, in the first embodiment, the reflector 6 is extended in the acoustic
radiation direction on the side of the bass speaker unit 2 and the treble speaker unit 3, while the
reflector 19 is used as a bass The speaker unit 13 is disposed in a direction perpendicular to the
acoustic radiation direction, that is, in a direction facing the diaphragm. First, as the basic
performance of the surround speaker system, it is desirable that the directivity is nondirectional
in the horizontal direction 360 ░ and narrow in the vertical direction (see FIGS. 11 and 12). For
that purpose, as shown in FIG. 8, the bass speaker unit 13, the treble speaker unit 14, the bass
speaker unit 15 and the treble speaker unit 16 are vertically stacked on the central axis x-x ',
respectively. Arranged symmetrically with respect to the central plane (horizontal plane) A.
However, the height of the speaker system becomes a problem when the speaker system for
surround sound is suspended from the ceiling. Therefore, by utilizing the symmetry of the
arrangement of the speaker units shown in FIG. 8 and the mirror image principle, the height of
the speaker system can be halved and the number of units can be halved. An embodiment taking
such points into consideration is shown in FIG. As shown in FIG. 9, the bass speaker unit 13 is
attached to the vertical surface 18, and the back of the bass speaker unit 13 is covered by the
bass cavity 20 with a necessary volume secured.
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A reflector 19 is disposed at a position (parallel to the vertical surface 18) facing the diaphragm
of the bass speaker unit 13 at an interval of D / 2 forward (in the drawing, upward) in the
acoustic radiation direction of the bass speaker unit 13 It is done. D is a size shown in the above
equation (1). A high-tone speaker unit 14 whose back is covered by the high-tone cavity 21 is
coaxially mounted along the central axis XX ? between the reflecting plate 19 and the low-pitch
speaker unit 13. The high sound speaker unit 14 is supported on the vertical surface 18 by a
support 22. It is preferable that the high sound cavity 21 be substantially spherical or curved so
as to illustrate the outer surface shape in consideration of the acoustic resistance of the sound
wave radiated from the low frequency speaker unit 13. It is preferable that the number of
columns 22 be an appropriate number so as not to be an obstacle in consideration of the abovementioned acoustic resistance. The distance between the acoustic radiation surface of the highpitched speaker unit 14 and the reflecting plate 19 is d / 2, and d is the size shown in the abovementioned equation (3). Furthermore, a plurality of ring-shaped filters 23 are disposed between
the vertical surface 18 and the reflector 19 at intervals. The filter 23 is made of, for example, a
material having a high sound absorbing property such as glass wool felt, to increase the acoustic
resistance in the vertical direction (X-X 'force direction and further narrow the directivity of the
high range in the vertical direction). It is. With the above configuration, the speaker system
shown in FIG. 9 can have the characteristic of narrow directivity in the vertical direction with no
directivity in the horizontal plane 360 ░. In addition to this, the pair of bass speaker units 13,
the treble speaker unit 14 and the bass speaker unit 15, and the treble speaker according to the
inclusion of the symmetry reflecting plate 19 as shown in FIG. 8 and the mirror image principle.
One of the units 16 can be omitted, and the external dimension (particularly the height) can be
halved and the number of units can be halved. However, in order to omit one of the groups as
described above, it is preferable that the reflection plate 19 be a complete reflection surface, and
for that purpose, the length (or diameter) of one side of the reflection plate 19 is the division
frequency f It is confirmed that there is no problem in practical use if it is C degree so as to
correspond to the double of the wavelength of (2?), and it is possible to go further and use the
ceiling surface of the acoustic space 100. According to the experiment, the axis of the maximum
sound pressure level in the plane (vertical plane, see FIG. 8) showing narrow directivity is not
parallel to the reflection plate 19, but the low sound speaker unit 13 side (lower side The
direction was inclined to
The inclination angle is related to the size of the reflector 19, and the larger the angle, the
shallower the angle (ie, the closer to the reflector 19). In the case of a side of about 50 cm to 100
cm, which is the size of a practical reflection plate, it has been confirmed that the inclination
angle is about 15 ░ to 30 ░. As described above, according to this embodiment, it is possible to
realize an omnidirectional 360 ░ horizontal non-directional vertical narrow directional surround
speaker system with a size of 1?2 and a number of 1?2. FIG. 10 shows an example of use of the
speaker system of the second embodiment. That is, the reflection plate 19 is placed along the
ceiling surface 24 of the listening room and fixed so that the side wall surface faces the radiation
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surface of the sound wave. By arranging in this manner, the virtual sound source speaker unit
13A exists above the ceiling surface by the mirror image principle, and it becomes equivalent to
the virtual sound source speaker unit 26 existing in the horizontal direction, and good narrow
directivity Good reflected sound can be obtained. As described above, according to the first
aspect of the present invention, it is possible to miniaturize a speaker system which has narrow
directivity in the vertical direction and which is suitable for a surround speaker system.
According to the fifth aspect of the present invention, it is possible to miniaturize a speaker
system suitable for a surround speaker system, having nondirectionality in the horizontal
direction and narrow directivity in the vertical direction in the vertical direction.
[0002]
Brief description of the drawings
[0003]
1 is a cross-sectional view showing a first embodiment of the present invention, FIG. 2 is a
perspective view showing an example of a speaker system according to the first embodiment,
and FIG. 3 is a characteristic showing frequency characteristics of the speaker system of FIG. Fig.
4 is a perspective view showing another example of the speaker system of the first embodiment,
Fig. 5 is a characteristic view showing the frequency characteristics of the speaker system of Fig.
4, and Fig. 6 is a television apparatus of the present invention. 7 is a side sectional view of FIG. 6;
FIG. 8 is a perspective view showing the basic configuration of a speaker system according to a
second embodiment of the present invention; and FIG. 9 is a second embodiment of the present
invention. FIG. 10 is an explanatory view of the operation of the second embodiment, FIG. 11 is a
plan view showing an arrangement example of a general surround speaker system, and FIG. 12 is
an elevation view of FIG. FIG. 13 is a block diagram showing an example of a conventional
surround speaker system, and FIG. 15 shows the directivity of the speaker system of FIG. 13. FIG.
16 is a perspective view showing an example of a conventional surround speaker system. FIG. 17
shows the speaker of FIG. It is a characteristic view showing directivity of a system.
18 и и и vertical surface 19 и и и reflector plate 20 и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и 19
vertical surface 19 reflection plate 20 cavity for high-pitched sound 21 cavity for high-pitched
sound 22 post 22 column 23 filter 24 ceiling surface 25 sidewall surface и и и Virtual sound
source speaker 100 и и и Sound space 101 и и и Front speaker 102 и и и Thron tossy force 103 и и и
Effect speaker 104 и и и virtual sound source speaker 105 и и и virtual sound source speaker 106 и и и
virtual sound source speaker 107 иии Enclosure 108 иии Bass speaker unit 109 иии Bass speaker unit
110 иии High tone speaker unit 1 и и и Enclosure 2 и Bass speaker unit 3 иии High tone speaker unit 4
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Speaker unit for virtual bass 5 Speaker unit for virtual treble 6 reflector 6A reflector 6 ...
Reflective plate 7 ... Television device 8 ... Speaker system 9 ... Glass plate 10 ... Loudspeaker
speaker unit 11 ... Cabinet 12 ... Filter 13 ... Bass speaker Unit 14A: virtual sound source speaker
unit 14: high sound speaker unit 15: bass sound speaker unit 16: high sound speaker unit 17:
horizontal surface 111: high sound speaker unit 112 listener
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