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[Industrial field of application] The present invention is directed to a directional C conventional
technology in which a plurality of speakers are disposed at an appropriate distance so that strong
sound pressure can be obtained in a specific direction by the interference of the sound waves. As
a conventional speaker apparatus having this kind of directivity, the tone zone system of FIG. 8 in
which a large number of speakers are arranged in a line is known. [Problems to be Solved by the
Invention] In this tone Zoleley system, as shown in FIG. 8, since the speakers sp are arranged in a
row at a certain distance d apart, the sound pressure of the two speakers sp is λ center P, in the
direction of 90 degrees from the axis P0. Then, at the frequency f0 where d = (λ = wavelength),
the phase difference is 180 degrees, and the sound pressure is zero. However, at the frequency
λ = d, P ,. In this case, the phase difference of 360 degrees, that is, the same phase is reinforced.
If this condition is displayed as a directivity pattern, the condition shown in Fig. 5 is obtained.
Therefore, the directivity characteristics of the tone zone speaker system of Fig. 8 are indicated
by the solid line A in Fig. 9 in the middle range and the dotted line B in the low range. It became
a characteristic and sufficient directivity characteristics were not obtained. In addition, since the
distance between each speaker sp is required to be d =, the entire speaker device is increased in
size. Furthermore, since the loudspeakers sp are arranged in a line, the directivity in the direction
perpendicular to this row is nearly non-directional, and is therefore not suitable when directivity
in two directions is required. The SUMMARY OF THE INVENTION The present invention
eliminates the above-mentioned drawbacks of the conventional speaker apparatus having
directivity by a plurality of speakers, obtains strong directivity in two orthogonal directions, and
can be miniaturized. It is an object of the present invention to provide a speaker device having
[Summary of the Invention] The present invention relates to a speaker device having directivity
for achieving the above-mentioned object, in which a cotton connecting the centers of two low
frequency speakers and a line connecting two high frequency speakers are crossed. Horizontal
and vertical spacings d. , D2 are set to ± 50% of the wavelength of the division frequency and
half to one fourth of d ,. DESCRIPTION OF THE PREFERRED EMBODIMENT Next, FIG. 1 shows
one embodiment of the present invention, FIG. 2 shows its principle, and FIG. 3 shows its
directivity characteristic, which will be described below. In FIG. 1, Lz and Lr are low-pass
speakers, arranged in the same dimension as the wavelength λ0 of the division frequency fc
between the high-pass speakers H, 5 and Hr in both horizontal and vertical directions There is.
The horizontal and vertical intervals d2 of the high-pass loudspeakers H, 5 and Hr are arranged
at a quarter of d, and a line connecting the centers of the low-pass loudspeakers LI and Lr and
the high-pass loudspeaker Hz, The line connecting the centers of Hr is orthogonal to that.
Then, a signal is input to the low frequency speakers LIl and Lr through a low pass filter that
attenuates -6 dB at the division frequency fc and -16 dBfi at 2 fc, and the high frequency
speakers Hp and Hr receive fc 12 dB at fc Signals are input through the high pass filter.
Assuming that the speakers Lz, Lr, H, g, Hr have the same volume velocity U and can be regarded
as a point sound source, they are equivalent as shown in FIG. A point P of a distance r which is
sufficiently separated in the direction of 90 degrees with respect to a point P6 on the front axis
of the speaker arranged in this manner. The synthetic sound pressure Pt at is expressed by the
following equation. C: sound velocity G1; low-pass filter α; low-pass filter G2; high-pass filter β:
high-pass filter gain filter phase filter gain filter phase filter phase ratio α, 0, G2 sea 18 dB (- 0. 1
2 5), so that tt + z is the same as UX 2 cos (k), so G1 = 0.5, α = −G2 = 0.5, πβ =, and the highpass filter If it is assumed that the polarity π of is reversely connected, β =. Therefore, next,
frequency f, = 2 fe = 4 f. The equation is completely the same as the equation (2) except that the
phase on the high frequency side is different because G1 is 0.125, G2 is 1, and βΣ0. That is,
next, at fe which is an intermediate frequency between f and f2, dZ cos (k-)) where fc = 2 f. = D1
d, = λ ,, d = = where the wavelength at λ c: fc and therefore d. The sound pressure P at P0 on
the central axis further, because of cos (k) cos cos (π) 2-1. Since the ratio of the absolute value of
the sound pressure in the 90-degree direction to the on-axis sound pressure is f + and fz-fe,
respectively, the on-axis sound pressure P ,. Will be attenuated by more than 20 dB. The above is
the case where the speaker itself has no directivity at all, and since the actual speaker has
directivity, a larger amount of attenuation can be expected. Furthermore, at an angle between 0
° and 90 °, the phase π difference due to the distance difference of the sound pressure from
each speaker is within each band and a peak is produced although the attenuation effect due to
cancellation is reduced. Absent. Therefore, as shown in FIG. 3, an ideal directivity characteristic in
which the sound pressure attenuates smoothly can be obtained. Further, since it is desirable that
each speaker has a sharp directivity, it is possible to obtain better narrow directivity
characteristics by attaching a horn baffle to a horn type speaker or a cone type speaker.
In this case, one drive speaker is provided for each of the high frequency band and low frequency
band, the sound path is divided into two by the horn section, and two horn openings are provided
each for the same effect as the above-described four speakers It is possible to get An example of
this structure is shown in FIG. The above is the basic configuration of the present invention, and
although narrow directivity can be obtained for a band of two octaves of f and -f2 by setting four
loudspeakers as one set, two loudspeakers are additionally arranged every two octaves. By
maintaining the above relationship, that is, by arranging at intervals of 4 for extension to the
high band side and at intervals of 4 times for extension to the low band side It can be expanded.
The intervals d1 and d2 of the four speakers do not necessarily have to be exactly d, = λ, and d2
= d, and the directivity characteristics of the speakers themselves, the cabinet to which it is
attached, or the shape of the baffle In some cases, conditions slightly deviated from the above
conditions may exhibit better narrow directivity characteristics, because the diffraction effect due
to etc. also affects. However, it has been found by experiments that it gets worse when the
following range is exceeded. なお、d,,d. Is basically the same size in both horizontal and
vertical directions, but it is not necessarily limited to the same size because slightly different sizes
may show better strong directivity characteristics due to the above factors. Furthermore,
according to the arrangement of the present invention, it is also possible to use a loudspeaker
having an outside dimension exceeding the spacing of the loudspeakers, which is more effective
because the directivity characteristic of the loudspeaker itself becomes sharp. In particular, when
it is desired to enhance the directivity in either the horizontal or vertical directions, the direction
is obtained by using an elliptical speaker as shown in FIG. 7 or by using a speaker using a
rectangular diaphragm. It is also possible to further improve the directivity of [Effects of the
Invention] As described above, according to the present invention, by arranging at least four
speakers as a pair for low frequency and high frequency as described above, good in both
horizontal and vertical directions can be obtained. A directional characteristic is obtained.
Furthermore, since the spacing is dimensioned to horizontal and vertical, the linear spacing of
both speakers is greater than the horizontal and vertical spacing, and loudspeakers with larger
dimensions can be used, so the directivity is sharper You can also get
Brief description of the drawings
1 is a front view of an embodiment of the present invention, FIG. 2 is its principle diagram in the
horizontal and vertical directions, FIG. 3 is a directivity characteristic diagram in the horizontal
and vertical directions, and FIG. 4 is two speakers. Sound pressure explanatory view, FIG. 5 is its
directional characteristic view, FIG. 6 is a sectional view of another embodiment of the present
invention, FIG. 7 is a front view of still another embodiment, and FIG. 8 is a conventional tone
zone system FIG. 9 is a directional characteristic diagram of FIG.
Lz, Lr: Low frequency speaker, Hz, Hr: High frequency speaker, d, ... L, g, interval of Lr, d2 ... Hz,
interval of Hr.