JPS6056038B2 - Constant directional speaker system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a directivity characteristic that monotonically decreases with respect to angle, and a significant portion of the characteristic that remains the same over a wide frequency range. This invention relates to a constant directional speaker system that exists in a directional characteristic at an angle.

Generally, in two-channel stereo, if you listen at a position that is shifted to the side from the bisector of the line connecting the speaker systems, the sound image will be biased toward the speakers near the listening position.

Conventionally, as a countermeasure against this problem, a system has been proposed that aims at constant directivity using an acoustic filter made of a sound absorbing material.

However, in such a system, since the relationship between the sound source position and the filter is inappropriate, the directivity deviation with respect to frequency does not become very small. There is also a proposal to obtain constant directivity by arranging the sound sources at uneven intervals, making the low-frequency directivity as sharp as possible, and moving the sidelobe generation frequency in the high-frequency range to as high a frequency as possible. cannot be said to have constant directivity because the sharpness of the main lobe itself changes depending on the frequency.

In order to solve this problem, the present invention provides speakers with directivity that increases the output sound pressure of speakers far from the listening position and lowers the output sound pressure of speakers close to the listening position. An object of the present invention is to provide a constant directivity speaker filter that expands the range in which a good stereo feeling can be obtained.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Figure 1 shows an example of using three speakers.
The speakers SPI, SP2, and SP3 are arranged at irregular intervals on the wiring.

In this case, the distance between speaker SP and speaker SPo is d,
, speaker SP. and the distance between speaker SP3 is d. Let d, >d0. Figure 2 shows the filter circuit connected to the speaker.If only the resistor RL of the speaker SP connected to the filter has an electrical impedance of 1, then
The degree of enhancement or reduction in the high frequency range with respect to the output of the speaker due to the connection of the filter is determined by a constant, as shown in the filter characteristic example shown in FIG. That is, FIG. 2a shows a high-frequency reduction filter circuit, with a resistance R and an inductance L.
Figure 2 shows the capacitor C and resistor R.
A high-frequency enhancement filter circuit consisting of a parallel circuit of ' is shown, where the ratio of resistance R to resistance R is K1 resistance R'' and resistance value RL.
Letting the ratio of K'' be expressed by the following formula.

↓l −νI−1shi Koj? ? l? ?
! Also, the crossover frequency of the circuit shown in FIG. 2a is F. and the crossover frequency of the circuit shown in FIG. 2b is F. '' holds true, and the degree of high frequency reduction of the high frequency reduction filter circuit shown in Figure 2a is determined by the constant K, and as shown in Figure 3a, the horizontal axis represents the frequency f1 and the vertical axis represents the level. Frequency F as PdB.

It can be seen that as the constant K increases in the direction of the arrow from the vicinity, the attenuation increases as the frequency increases. The degree of high-frequency enhancement of the high-frequency enhancement filter circuit shown in FIG. 2b is determined by the constant K'', and as the constant K'' increases in the direction of the arrow from near frequency FJ as shown in FIG. 3b, It can be seen that the higher the frequency, the greater the degree of enhancement. Next, returning to FIG. 1, a high-frequency enhancement filter is connected to the speaker SP3, and in order to increase the efficiency of the entire speaker system, the constant K'' indicating the degree of enhancement is set to be small, about 0.5.Speakers SP1, SP2 A high-pass reduction filter is connected to each to further attenuate the voltage to 1+K.Also, the constant of the filter connected to speaker SPl is K1,
Assuming that the identified number of filters connected to speaker SP2 is K2, the constituent elements of each filter are selected so that K1>K2.

The directional characteristics of the speaker system configured as described above are characterized by the phase characteristics showing the relationship between the frequency f and the phase θ of the circuits shown in FIGS. 4A and 4B, which correspond to FIGS. 2A and 2B, respectively. , is explained by the directional characteristics shown in FIGS. 5A and 5B. In other words, in the arrangement of each speaker SPl, SP2, and SP3 shown in FIG. 1 when no filter is connected, the fifth
As shown in Figure b, there is relatively no directivity at low frequencies, but as the frequency increases, the characteristic becomes directional with many lobes. On the other hand, as mentioned above, the filters are connected to the speakers SP1 and SP2.
, SP3, the dip Q that occurs between the lobes of the directivity characteristic at high frequencies becomes smooth and the directivity becomes weaker, as shown in FIG. 5a. In addition, each speaker SPl,
The constant K of the circuits of SP2 and SP3 is that the circuit of speaker SP3 is small due to high frequency enhancement, the circuit of speaker SP2 is small due to high frequency reduction, and the constant K of the speaker SP1 circuit is large due to high frequency reduction. For this reason, the frequency f is F from the phase characteristics of the high frequency reduction circuit shown in FIG. 4a. Each speaker S nearby
The phase difference between P,, SP2, and SP3 is large and becomes smaller as the frequency f becomes higher.Similarly, from the phase characteristics of the high frequency enhancement circuit shown in Fig. 4b, when the frequency f is around FJ, each speaker SP1, SP2, The phase difference between SP3 is large and becomes smaller as the frequency f becomes higher. Due to the above difference in phase characteristics, the frequency F.

In the vicinity, the directivity characteristic is such that the center line r of the main lobe deviates from the front direction as shown in FIG. Frequency F. By setting the lower limit frequency of the desired directional characteristic, it is possible to correct the spread of the directional characteristic in the low range and obtain a constant directional characteristic over a wide frequency band. As explained above, according to the speaker system of the present invention, the input voltage of each speaker arranged in a straight line is changed by the high frequency enhancement filter and the high frequency reduction filter, so that the apparent size of the sound source becomes smaller as the frequency increases. As a result, a speaker system with constant directivity over a wide band can be obtained.

In addition, the range in which good stereo signals can be obtained indoors has been greatly increased, allowing a large number of people to enjoy the system. It is also suitable as a loudspeaker system for outdoor halls and the like.

[Brief explanation of drawings]

The drawings are for explaining the present invention; FIG. 1 is a diagram showing the arrangement of speakers, FIG. 2 is a filter circuit to be combined with the speaker in FIG. 1, and a is a high-frequency reduction filter circuit diagram;
is a high-frequency enhancement filter circuit diagram, Fig. 3a is a frequency-level characteristic diagram of the circuit shown in Fig. 2a, Fig. 3b is a frequency-level characteristic diagram of the circuit shown in Fig. 2b, Fig. 4a is a phase-frequency characteristic diagram of the circuit shown in FIG. 2a, FIG. 4b is a phase-frequency characteristic diagram of the circuit shown in FIG. 2b, and FIG. In the diagram showing the characteristics, a is the second
A diagram showing the case where the filter shown in the figure is coupled to the speaker of FIG. 1, and b is a diagram showing the directional characteristic when the filter of FIG. 2 is not provided.

Claims (1)

[Claims] 1 All of the plurality of speakers are arranged in a straight line facing the listener side, and the filters connected to each of the speakers are arranged in order from high frequency enhancement to high frequency reduction, and the plurality of 1. A constant directivity speaker system, characterized in that the distance between the speakers increases as the connected filter increases from high frequency enhancement to high frequency reduction.