JPH0716278B2 - Multi-unit speaker system - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a multi-unit speaker system with improved vertical directional characteristics.

2. Description of the Related Art and Problems When a speaker arranged at a constant height is located on the side of a listener, it is generally considered that the optimum listening point is on the central axis of the speaker. However, when listening while seated like an on-vehicle audio system, the position of the listener's ears differs depending on the height and the like, and it is sufficiently predicted that the listener's ears do not lie on the central axis.

FIG. 1 is this explanatory view, 1 is a seat, 2 is a listener seated there, 3 is its ear, 4 is a side wall of a vehicle compartment, and 5 is a multi-unit speaker system called a roof side speaker. Although this speaker system 5 is movable in a direction orthogonal to the plane of the drawing, its vertical directivity is a problem here. 6 is a central axis in the radial direction of the system, and θ is an angle formed with the listening point (here, the ear) 3. Generally, even if there is such an angle θ to some extent, it can be heard with a slight deterioration in characteristics, but if the system 5 is multi-united as shown in FIG. 2 to increase the sound pressure, dipping in the audible frequency band becomes a problem. Become.

That is, the speaker system 5 shown in FIG. 2 has six small high-frequency speaker units 7 (for example, diameter 3 cm).
It is arranged in two rows on the x-z plane at a vertical interval d. Point O is the center point of the speaker system 5, and P ₀ is one point on the center axis (y-axis) 6 passing through the point O. Now, in order to consider the vertical characteristics of this system, assume a listening point P _θ on a line forming an angle θ with the central axis 6 in the yz plane. When A to F are the respective center points of the speaker units 7, the distance from the listening point P _θ to the point A And the distance to point B Can be expressed by the following equations.

Therefore, the distance difference from the listening point P _θ to the points A and B is Becomes If the frequency of the sound emitted from the speaker unit 7 is f, the wavelength is λ, and the speed of sound is v (340 m / s), then v
= Fλ, the minimum value of the frequency (dip frequency) f _θ at which the sounds emitted from points A and B interfere and weaken can be obtained by the following equation.

So, as a specific example, When d = 44 mm, the equation (4) is simplified as follows.

By substituting the numerical value example of θ in this equation (4 ′), the dip frequency f _θ shown in the following table is obtained.

3 to 7 show these measured values (frequency characteristics), and a dip (indicated by an arrow) was observed at a frequency substantially matching the calculated value. The dip arranged vertically when viewed from the listening point P _theta (lateral direction in this case is not a problem) but caused by the difference in distance to each speaker unit, and P _theta
Similar calculations are valid for C, D and E, F. Then, in the arrangement shown in FIG. 2, between P _θ and A, B, P _θ and C, D
During this period, since the distance difference between P _θ and E, F is almost the same, the frequencies of the dips are substantially the same, and the amount of dips on the overall frequency characteristic becomes remarkable.

An object of the present invention is to prevent the inevitable dip frequencies generated for each unit pair from overlapping as a whole so that a large dip in the audible band does not occur.

According to the present invention, a plurality of loudspeakers having the same characteristics for reproducing the same signal are arranged on a circular arc line at unequal intervals, and heights differ from a listening point in a front direction and a vertical direction on a plane including the circular arc line. It is characterized in that the difference between the distances to the arbitrary two speakers and the difference between the distances to the arbitrary two speakers having different heights are different, which will be described in detail below with reference to the drawings.

Embodiment of the Invention FIG. 8 is a principle explanatory view for explaining the principle of the present invention. In this example, six speaker units 7 having the same characteristics are arranged on an arc 8 having a radius r at equal intervals d. When the arrangement surface of the speaker unit 7 is the xZ plane, the y axis is the central axis 6 of the system 5. P ₀ is one point on the central axis 6, and P _θ is a listening point on a line forming an angle θ with the central axis 6 on the yZ plane. When θ = 0 ° and P _θ = P ₀ , the distance from the listening point P ₀ to the center point of each speaker unit 7 is Therefore, at the listening point P ₀ , the outputs of the respective units 7 are in phase and the interference between the units is eliminated, so that the optimal listening position is achieved. FIG. 9 shows frequency characteristics in this case.

On the other hand, if the listening point P _θ is moved vertically, And also Therefore, the dip frequencies generated by the unit pairs separated in the vertical direction are all different. Therefore, dips do not overlap with similar frequencies and a large level drop does not occur. In FIGS. 11 and 12, θ = −15 ° and θ = −30 measured by shifting the listening point P _θ downward.
It is a frequency characteristic of °. The same applies to the case where the listening point P _θ is moved upward. Figure 10 shows θ = +15
It is the frequency characteristic measured as °. In both cases, no large dip as in the past is recognized.

As described above, the principle of the multi-unit loudspeaker system of the present invention is based on a unit arrangement in which dip frequencies caused by a difference in distance from any two units to a listening point do not overlap. Therefore, as long as this is the case, the units may be randomly arranged in the same plane. However, this makes the ideal listening point P ₀
Is hard to set or does not exist. Therefore, the arrangement on the circular arc has been described as a unit array in which the ideal listening point P ₀ is on or near the central axis 6 and the dip frequencies of the units do not overlap.

In FIG. 8, a plurality of units 7 are arranged at equal intervals on a circular arc so that the principle can be easily understood. If the principle of FIG. 8 is used as it is, Therefore, there is a problem that the left and right unit pairs at the same height and the left and right unit pairs at the same height, which are different from the left and right unit pairs, are affected by the dip.

The present invention has also solved this problem.As shown in FIG. 13, a plurality of speakers having the same characteristics for reproducing the same signal are arranged on a circular arc line at unequal intervals, and a front surface with respect to a plane including the circular arc line is arranged. In addition, the difference in the distance from the listening point in the vertical direction to any two speakers having different heights is different from the difference in the distance to any two speakers having different heights.
That is, the above The above is not established.

Therefore, according to this embodiment, the dip suppression is very effectively performed. FIG. 14 shows a modified example in which the case of the system 5 is formed in the same shape along the unit array.

In each of the above-mentioned examples, the dip in the left-right direction does not matter, but this is because the system 5 can be optimized by moving it in the x-axis direction in FIG. Of course, the directions of up, down, left and right are for convenience of description.

EFFECTS OF THE INVENTION As described above, according to the present invention, a large dip does not occur even if the listening point shifts in the vertical direction, so that it is possible to guarantee the reception of good frequency characteristics even if there is a difference in the height of the listener. There are advantages.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a shift between a speaker system and a listening point in the vertical direction, FIG. 2 is a configuration diagram showing an example of a conventional multi-unit speaker system, and FIGS. 3 to 7 are frequency characteristics in the vertical direction. FIG. 8 is a principle explanatory view for explaining the principle of the present invention, FIGS. 9 to 12 are vertical frequency characteristic diagrams thereof, and FIG. 13 is a configuration diagram showing an embodiment of the present invention. FIG. 14 is a block diagram showing a modification thereof. In the figure, 5 is a multi-unit speaker system, 7 is a speaker unit, 8 is an arc line, and P _θ is a listening point.

Claims (1)

[Claims] 1. A plurality of loudspeakers having the same characteristics for reproducing the same signal are arranged on a circular arc line at unequal intervals, and the height is different from a listening point in the front and up and down directions with respect to a plane including the circular arc line. A multi-unit speaker system, wherein a difference in distance to one speaker and a difference in distance to any two speakers having different heights are different from each other.