JPH02237299A - Speaker equipment having directivity - Google Patents

Abstract

PURPOSE:To obtain a sharp directivity over the entire sound frequency by specifying the attenuation characteristic in a crossover frequency and a distance of two sets of speakers using two sets as a pair and containing a woofer into a cabinet with front face open type. CONSTITUTION:A signal is supplied through a low pass filter with-12dB per octave at a crossover frequency fc and a signal is supplied through a high pass filter with the attenuation characteristic at the frequency fc in the middle of 1st speakers 1, 1' used as 2 sets as a pair arranged at a distance d1 of the wavelength of the frequency fc. Then 2nd speakers 2, 2' with 2 sets as a pair are arranged at a distance of d1/4 and at least the woofers 1, 1' are contained in a cabinet 3 with front face opening type. Thus, even when the distance of the arrangement of the speakers is narrow, a speaker equipment having a directivity ensuring a sufficient directivity at a low sound frequency is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a system in which a plurality of speakers are arranged at appropriate distances, so that a strong sound pressure can be obtained in a specific direction through the interference of the sound waves. The present invention relates to an improvement of a speaker device having such directivity.

[Conventional technology]

Conventional speaker devices with this type of directivity include:
The I. Inzoile system shown in FIG. 2, in which a large number of speakers are arranged in a row, is known.

(Problem to be solved by the invention) This tone delay method is based on the speaker s as shown in Figure 3.
Since p are arranged in a line separated by a certain distance d,
The sound pressure from the two speakers SP is at the center P. From 90
In PIIO in the degree direction, the frequency f is d - π/2 (π one wavelength). Since a phase difference of 90 degrees occurs, they cancel each other out, and the sound pressure becomes 0.

And the central axis P. Since they strengthen each other, a peak of sound pressure level is produced, and the center axis P. At an angle Pθ intermediate between P and 0 in the 90 degree direction, it becomes weaker from Po to P qo,
Directional characteristics shown by the solid line in FIG. 4 are obtained.

However, the frequency f of the speaker sp. When it comes to −d−π,
P. In this case, the directional characteristics become as shown by the dotted line in Figure 4 because they strengthen each other.

For these reasons, the speaker system of the 2M 1--Nzuile system has a directional characteristic shown by the solid line 8 in Figure 5 in the middle range, and a directional characteristic shown by the dotted line B in the low range, and is not sufficient. I couldn't get it.

Furthermore, since the distance between each speaker SP must be d=-.π/2, there is also the drawback that the entire device becomes larger.

In addition, Parameter 1, lithospiracy, which uses highly directional ultrasonic waves, has been put into practical use, but it requires an ultrasonic generator (modulator) and it is difficult to obtain a large sound pressure level. However, it has not become widely popular due to problems such as the difficulty in reproducing bass frequencies in principle.

[Object of the Invention] The present invention eliminates the above-mentioned drawbacks of the conventional speaker device having directivity using a plurality of speakers, and makes it possible to ensure sufficient directivity in the bass range even if the speaker arrangement spacing is narrow. An object of the present invention is to provide a speaker device having directivity.

[1 SUMMARY OF THE INVENTION] The present invention relates to a speaker device having directivity that achieves the above-mentioned object, and is directed to a speaker device having cross-ohno/one frequency fc and passing through a low-pass filter of -12 dB per octave.
A high-pass filter with the same attenuation characteristic is passed through the center of a pair of first speakers arranged at an interval d, with a wavelength of c, and a second set of two speakers arranged at an interval d,/4 is passed through a high-pass filter having the same attenuation characteristic. Speakers are arranged, and at least the first speaker is housed in a rear-opened cabinet.

[Embodiments of the invention]

An example of implementing the invention will now be described with reference to FIG.

Speakers 1 and 1' for low range and speaker 2 for high range,
2' is the cross-oher frequency fc for the full plate 3.
They are arranged at an interval d1 equal to the wavelength λc and an interval d2 of λC/4=(II/4), and the phase adjustment plate 4 is provided on the Hanfle plate 3 so as to protrude by hl in the front and h2 in the rear.

Then, there is a cross over frequency f between the bass range speaker 1' and the treble range speaker 2, 2'. In contrast, the bass range reproduction limit frequency f7! f1! -f7! /4, set the following dimensions.

輔-120 Sound receiving point P. f from to the speaker? Ij.
u:I[ρ1, P from the rear of the speaker. The distance to (dotted line in Figure 1)! 2, d (g ””l.z f2+ = 1−−−λpI
! 2 − n , −1−−−1−−−λpλp::f
The wavelength applied to p and the low-pass filter to the bass speaker 1 is -6 dB at C, -18 dB to 2 fc, and the high-pass filter to the treble speakers 2 and 2' is -5 dI at fc.
1, 2L has an attenuation characteristic of 12 clB per octave of -18 dll.

If you set it up like this, the bass range speaker 1 on one side,
Considering the high frequency speaker 2, the frequency f.
On-axis sound pressure P at . Therefore, the sound pressure P in the 90 degree direction. is I23 = point p at 90 degrees from the front of bass range speaker 1
,,distance to o! 4 ・Point P at 90 degrees from the rear of bass speaker 1
,. Therefore, when h1"" hz, the distance is ℃, shiC, Therefore, for the 90 degree direction, as in the case of f, next, f
− 2 f p−f c/ 2, d, is 3/
The axis is equivalent to 4λp and the sound pressure P is 2. is calculated backwards as in equation (1).Next, when f=fC, dρ corresponds to 3/2λ2, so the axis is 20 sound pressure P. Therefore, since the wavelength becomes shorter, it becomes directional.

The directivity coefficient D representing this directivity is given by the radius of the piston 1.
In the disk, kasinθ J1 is expressed by a first-order Hessel function.

For example, if λβ is a -, then at a position tilted by θ from the axis, for example at 90 degrees, in other words, at fc, it is possible to sufficiently attenuate the sound from the rear side of speaker 1, and the axis at that time The upper sound pressure becomes almost only the sound from the front.

When f>2fc, the sound is naturally attenuated by the directivity characteristic of the speaker 2 itself on the high frequency range side.

Therefore, it is possible to realize a speaker device with sharp directivity over the entire sound range.

〔Effect of the invention〕

As described in Section 2 of the present invention, the attenuation characteristics at the cross-oher frequency and the spacing between the two sets of speakers,
By housing the low-range speakers in a rear-open cabinet, sharp directivity can be obtained over the entire sound range.

In addition, the spacing between the speakers on the low frequency side is sufficient to be the wavelength of the 1'' swoher frequency, making it possible to achieve miniaturization of the speaker device as a whole. This has the effect of making it possible to obtain directivity in the bass range, which has been difficult to achieve.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the principle of an embodiment of the present invention, Fig. 2 is an illustration of the principle of the conventional 1/2-way system, Fig. 3 is an explanatory diagram of the sound pressure of two speakers, and Fig. 4 is its polar coordinates. FIG. 2 is a diagram showing the directional characteristics according to the polar coordinate system of the fifth section 1. 1, 1'... Speaker for low frequency range, 2, 2'... Speaker for high frequency range, 3... Full board, 4... Phase adjustment plate. 0° Fig. 4

Claims (1)

[Claims] -6dB at crossover frequency f_c, - at 2f_c
A signal is supplied through a low-pass filter with an attenuation characteristic of 18 dB or more, and is placed at the center of a pair of first speakers arranged at an interval of wavelength λ_c of f_c.
The signal is supplied through a high-pass filter with an attenuation characteristic of -18 dB or more at 6 dB, f_c/2,
What is claimed is: 1. A speaker device having directivity, characterized in that a set of two second speakers are arranged at an interval of 4.5 mm, and at least the first speaker is housed in a cabinet with an open rear surface.