JPH0570995B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a horn speaker that reduces disturbances in sound pressure frequency characteristics by appropriately setting the shape of the horn.

Figure 1 shows a half cross section of a speaker generally called a radial horn speaker (a type of Bessel horn), where 1 indicates the throat section 3 of the horn 2.
a driver for imparting acoustic energy to the
4 and 5 are left and right walls of the horn 2, 6 and 7 are upper and lower walls of the horn 2, and 8 is an opening of the horn 2.

FIG. 2 is a partially sectional side view taken along line A--B in FIG. 1.

This horn 2 has planar left and right walls 4 and 5, and the center point 0 of the opening angle θ is set near the throat portion 3. The upper and lower walls 6 and 7 of the horn 2 have a shape whose area changes according to an exponential function in response to a change in the distance from the upper and lower center point 0 toward the opening 8. In other words, the horn 2 in Fig. 1 has a cross-sectional shape along the center line A-B,
It is rotated by θ with the center point 0 as the center of rotation.

Radial horns with this type of structure have features such as easy design of the directivity angle and relatively little change in sound pressure distribution within a given directivity angle. Disturbances occur, resulting in peaks and dips in the sound pressure frequency characteristics.

Figure 3 shows this situation. Compared to the characteristics when an infinite length exponential horn is installed (solid line), the characteristics when a radial horn is installed (dashed line) are greatly disturbed, especially in the reduction. I know that there is.

The reason for this is thought to be that standing waves due to the length of the horn 2 are generated within the horn 2, causing disturbance in the radiation impedance. In other words, this is thought to occur because the length from the throat portion 3 to the opening portion 8 is constant in any direction of the opening angle θ.

In view of these conventional problems, the present invention provides a speaker that reduces disturbances in sound pressure frequency characteristics in the low range and provides good sound quality.

An embodiment of the present invention will be described below with reference to FIGS. 4 to 7.

In Figures 4 to 7, 9 is a driver, 1
0 is the horn, 11 and 12 are the left and right walls of the horn 10,
13 and 14 are the upper and lower walls of the horn 10, and 15 is an opening of the horn 10. The left and right walls 11 and 12 are configured in a planar shape. On the other hand, the upper and lower walls 13, 14
is configured in such a shape that the area surrounded by lines that are equidistant from the aperture surface toward the center point 0 changes the Betzel function in accordance with the distance from the aperture surface toward the center point 0.

That is, as shown in FIG. 7, the opening 15 of the horn 10 has a curved line determined by a certain distance (radius) from a point P behind the center point 0. The curve of this opening 15 is defined as A, and the left and right walls 1
Lines O-D, O- that divide the opening angle of 1, 12 into 12 equal parts
E, O-F, ... When several lines formed by connecting points that are equidistant from the opening surface toward the center point 0 on O-J are B, H, D, and H, each line I~ The area of the portion surrounded by E is configured to change according to the distance from the aperture surface to the lines A to E by a Bessel function (for example, an exponential function). Figures 5 and 6 are A'- of Figure 4.
It shows the B′ cross section and the A′-O′-C′ cross section.
It can be seen that the lengths of the upper and lower walls 13, 14 are longer in the A'-O'-C' cross section.

With this configuration, the left and right walls 1 of the horn 10
The length from the throat portion 3 to the opening portion 15 changes depending on the direction of the opening angles 1 and 12. Therefore, unlike conventional radial horns, standing waves of specific frequencies within the horn 10 are not generated, and the frequencies at which the standing waves occur are dispersed. As a result, disturbances in radiation impedance are also reduced, making it possible to realize a flat sound pressure frequency characteristic as shown by the dashed line in FIG.

FIGS. 8 and 9 show an example of application of the present invention, and parts having the same functions as those in FIGS. 4 to 7 are given the same reference numerals, and explanations thereof will be omitted. Driver 9 is
Center pole 16, magnet 17, plate 18, voice coil 19, bobbin 20, diaphragm 2
1, etc., and an equalizer 22 is provided in front of the diaphragm 21. This equalizer 22 aligns the phase of the sound waves from the diaphragm 21, smoothes the curve area change of the horn 10, connects the upper and lower walls 13 and 14 of the horn 10, and improves the structural strength of the horn 10. It plays a role in preventing the "squeal" of the Further, the front surface of the horn 10 is covered with a dust cap 23.

As described above, in the present invention, the area surrounded by lines equidistant from the horn opening surface toward the center of the horn on the upper and lower walls of the horn changes with the Betzel function depending on the distance from the opening surface toward the center point. The length from the throat to the opening changes depending on the direction of the opening angle of the left and right walls, so standing waves with specific frequencies are not generated like in conventional radial horns. As a result, disturbances in radiation impedance are reduced and a flat sound pressure frequency characteristic is obtained.

[Brief explanation of the drawing]

Fig. 1 is a half-sectional view of a conventional radial horn speaker, Fig. 2 is a half-sectional view taken from line A-B in Fig. 1, Fig. 3 is its sound pressure frequency characteristic diagram, and Fig. 4 is a diagram of the present invention. FIG. 5 is a half-sectional view of a speaker according to an embodiment;
Fig. 6 is a cross-sectional view taken along lines A-B and A-C in Fig. 4, Fig. 7 is a cross-sectional view for explaining its structure, and Figs. 8 and 9 are front views showing examples of its application. FIG. 9...Driver, 10...Horn, 11,1
2... Left and right walls, 13, 14... Upper and lower walls, 15...
Opening, 22... Equalizer.

Claims (1)

[Claims] 1 The center point of the opening angle of the left and right walls is near the throat, and when the upper and lower walls are oriented toward the above center from the opening surface, the area of the equidistant plane changes depending on the distance from the opening surface toward the center point. A speaker with a horn shaped like that.