JPS6362159B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speaker, and in particular an equalizer (sometimes referred to as a differential user) provided at the front of a diaphragm (sound wave radiation surface) for the purpose of improving sound pressure frequency characteristics including directional characteristics. ) regarding the configuration of

Conventionally, there is a method of improving sound pressure frequency characteristics by arranging a disk, an annular ring, a sphere, or the like in front of the sound wave emitting surface of a speaker. It is especially often used in dome-shaped speakers that have a dome shell diaphragm.
As shown in FIG. 1, this produces a dip d in the sound pressure frequency characteristic 1 due to the shape effect of the dome. For this reason, as shown in Fig. 2, an equalizer 3 such as a ring or a disc is placed in front of the dome diaphragm 2 to correct the phase shift of the sound waves generated from the center and end of the dome. , flattening the sound pressure frequency characteristics. Since these effects were known qualitatively, the shape was mainly selected empirically, and from the viewpoint of design, a symmetrical shape was also selected.

Particularly in recent years, these effects have been qualitatively and quantitatively analyzed using computers. An example is shown in FIG. This figure shows the diffraction effect of a rectangular or circular plate placed in a plane wave sound field. Here, D is the diameter of the disc or the length of one side of the rectangle, and λ is the wavelength.

In this way, the peak size is maximum when the wavelength λ and the size of the disk or rectangle match,
A dip occurs when D/λ≈2. At frequencies higher than that, peaks occur at odd multiples of D/λ, and D/λ
A dip occurs at even multiples of .

When disposing an equalizer 3 made of these discs, rings, or rectangular plates in an actual speaker, the diameter D _d of the diaphragm 4, the diameter D of the equalizer 5, the thickness of the equalizer 5, Its characteristics vary depending on the distance t and the gap g between the diaphragm 4 and the equalizer 5. However, as shown in FIG. 3, the diameter D of the equalizer 5 has a large effect.

In recent years, the playback frequency band has been increased using a driving method called node drive, in which a flat plate diaphragm with a sandwich structure using honeycomb and foam as a core material is connected to a voice coil at the node of the natural resonance mode of the diaphragm. There is a type of speaker that can be expanded significantly.

FIG. 5 shows an example of sound pressure frequency characteristics when this method is applied to a tweeter. In this method, since it is difficult to disperse the resonance of the diaphragm, a sharp peak P is generated on the sound pressure frequency characteristic 6. Since this peak P is sharp, it has a somewhat negative effect on sound quality.

An object of the present invention is to provide a method of acoustically canceling this peak P to flatten the frequency characteristics and further improve the directivity characteristics.

Speaker peak P frequency _h and equalizer 5
Match the frequency of the first dip of the diffraction effect of
cancel to flatten the frequency characteristics.

However, the frequency _h of the peak P of the speaker changes due to variations in materials and assembly. Therefore, it may not be completely canceled.

On the other hand, as shown in FIG. 3, the frequency of the dip due to the diffraction effect changes in inverse proportion to the diameter (size) D of the equalizer. Due to design constraints, the shape of the equalizer is often vertically and horizontally symmetrical, so that the path length for diffraction of sound waves is the same, and the frequency width w of the dip is narrow and sharp.

In the present invention, the shape of the equalizer disposed above the sound wave emission surface of the speaker is shaped as shown in FIG. 6 (frontward shape as seen from ). In other words, when the size of the equalizer 3 is large, the dip frequency becomes low, and when it is small, the dip frequency becomes high, so the shape is designed to have a synergistic effect. Figure 6 A is a Sui circle, B is a rectangle, C is a Sui circle with a circular hole, and D is a rectangle with a square hole. In addition, the combinations may be made so that the path lengths of the sound waves from each part of the diaphragm are different.

As a result, as shown in FIG. 7, when the aspect ratio of the rectangular plate is changed, a diffraction effect is obtained in which the dip width w of the diffraction effect is wide and the peak height is low.

Therefore, even if the resonance frequency _h of the speaker varies, it can be canceled.

Much of the implementation of the invention has been described above. Here, one specific example will be shown.

FIGS. 8 and 9 are cross-sectional views showing the structure of a speaker (flat tweeter) to which the present invention is applied.
Moreover, FIG. 9 similarly shows a front view.

A frame 8 is screwed to the magnetic circuit 7, a diaphragm 4 is adhered to the frame 8 via an edge 9, and the upper part of the voice coil 10 is connected to the diaphragm 4 and placed in the magnetic gap.

The equalizer 5 (diff user) of the present invention is attached to the frame 8 with a plurality of spokes 11 in order to maintain the gap g between the four diaphragms and the position thereof.

In the example tweeter, the diameter _D of the diaphragm 4 is φ28
mm, and the dimensions of the equalizer 3 are 24 mm x 22 mm square plate with a square hole in the center of each side 14 mm.

FIG. 10 shows the directivity characteristics (on-axis, 30°, 60°) when the equalizer 5 is not attached.

The effect of the equalizer 5 of this embodiment is shown in FIG. 5 by a dotted line 12. The peaks have been canceled and flattened. FIG. 11 shows the directivity characteristics when the equalizer 5 of this embodiment is attached. directional characteristics
The 30° characteristics have been significantly improved. Generally speaking, two speaker systems are placed for stereo reproduction, and ideally they should be placed 30 degrees from the left and right in front of the listener. The equalizer 5 of the present invention improves the 30° characteristic of the speaker system and significantly improves the sound quality.

According to the present invention, as described above, the peak on the sound pressure frequency characteristic due to resonance of the diaphragm can be canceled and flattened by matching the dip of the diffraction effect of the equalizer. As in the example, by changing the vertical and horizontal lengths of the equalizer, the width of the dip portion of the diffraction effect can be widened. For example, even if the resonance frequency _h of the diaphragm varies by about ±10%, Almost can be canceled. Furthermore, since the phase of the sound waves changes (the path length differs), the directional characteristics are also improved, which has the effect of improving the sound quality.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing changes in the sound pressure frequency characteristics emitted from the dome shell depending on the shape of the dome.
The figure is a cross-sectional view of a dome-shaped speaker equipped with an equalizer to improve the characteristics shown in Figure 1, Figure 3 is a frequency characteristic diagram of the diffraction effect of a rectangular disk placed in a plane wave sound field, and Figure 4 is A schematic diagram showing the positional relationship between the diaphragm and the equalizer. Figure 5 is a sound pressure frequency characteristic diagram when the tweeter using a conventional flat plate diaphragm and the equalizer of the present invention are added. Figure 6 is the shape of the equalizer of the present invention. FIG. 7 is a frequency characteristic diagram showing the features of the equalizer of the present invention, FIGS. 8 and 9 are cross-sectional views and front views when the equalizer of the present invention is added to a flat tweeter, and FIG. 11 is a directional characteristic diagram of a conventional flat tweeter, and FIG. 11 is a directional characteristic diagram of a flat tweeter to which the equalizer of the present invention having the configuration shown in FIG. 8 is added. 1, 6, 12... Sound pressure frequency characteristic, 2... Dome diaphragm, 3... Equalizer, 4... Flat plate diaphragm, 5... Equalizer, 7... Magnetic circuit, 8... Frame, 9... Edge, 10... Voice coil, 11 …spoke.

Claims (1)

[Claims] 1. In a speaker in which an equalizer is disposed opposite to the front surface of a diaphragm, the equalizer has a shape different from the front shape of the diaphragm, and a shape of the surface facing the diaphragm. A speaker characterized by being formed in an oval or rectangular shape. 2. The speaker according to claim 1, wherein a circular or rectangular hole is formed in the center of the equalizer.