JPH0566800B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a composite speaker that reproduces two or more different frequency bands in one unit.

Conventional configuration and its problems In recent years, planar diaphragms have been used as speaker diaphragms, but it is difficult to reproduce the audible frequency range with one speaker, so two or more speaker units are combined. It is used as This can be combined with a composite speaker in which multiple speaker units are arranged coaxially, or with separate speaker units attached to a speaker box.
There is a way to use it as a speaker system.

A composite speaker using conventional planar speakers will be described below.

FIG. 1 is a sectional view of a conventional composite speaker.
In Fig. 1, reference numeral 1 denotes an annular plane diaphragm for reproducing bass sounds. It is fixed to the edge 4 and the inner frame 5. Reference numeral 6 denotes a magnetic circuit, and a voice coil 8 is suspended from the magnetic circuit 6 via a damper 7, and the voice coil 8 drives the annular plane diaphragm 1. With the above configuration, a bass speaker is formed. Reference numeral 9 denotes a diaphragm for reproducing middle and high frequencies, which is provided on the inner frame 5 via an edge and is driven by a magnetic circuit 10 and a voice coil 11. The mid-high frequency speaker formed in this way is mounted on the support stand 12.
It is fixed to the magnetic circuit 6 for the bass speaker via. The driving force is transmitted to the voice coils 8 and 11 for each speaker via a frequency division circuit (not shown).
added to.

However, in the above configuration, the sound emitted from the diaphragm 9 for medium and high frequency reproduction is reflected by the edges 3 and 4 of the bass speaker and interferes with each other due to the difference in the axial sound and its path length. This had the disadvantage that the sound pressure frequency characteristics were disturbed.

This case will be described in more detail below.

Now, if the distance from the center of the diaphragm 9 to the edge 3 is Δl, then at a point r _n away on the axis of the diaphragm 9,
The sound wave p ₁ radiated directly on the axis (assuming that the sound is a plane wave and that the phase does not change when reflected from the end face of the edge) is p ₁ = P ₁ sin (ωt−kr)... (1) (where k=ω/c, P ₁ : amplitude, c: speed of sound,
ω: angular frequency). On the other hand, the sound wave p ₂ reflected from the edge end face is p ₂ =P ₂ sin {ωt−k(r+Δl)} (2) (where P ₂ is the amplitude). Since the edge 3 and the diaphragm 9 are formed concentrically, the distance Δl from the edge 3 to the diaphragm 9 is equal over the entire circumference of the edge 3.
The sound wave p ₂ becomes a reflected sound over the entire circumference of the edge 3, and has a very large influence on the sound wave p ₁ . The interference sound p in this case is expressed as follows.

p=P ₁ sin(ωt−kr)+P ₂ sin{ωt−k(r+Δl)
} =Psin(ωt−kr＋ _O ) ……(3) However, P=√ ₁ ² + ₂ ² + 2 _{1 2} (・
)
...(4) _O = tan ^-1 −P ₂ sin(k・Δl)/P ₁ +P ₂ cos(k・Δl
)...(5) Therefore, from equation (4), when the distance Δl is equal to 1/2 of the wavelength λ, the amplitude P of the interference sound p becomes P=P ₁ − _{P 2} ...(5) and they cancel each other out. When the distance Δl is equal to 1/4 of the wavelength λ, P = P ₁ + P ₂ ...(6) and they strengthen each other. Therefore, reflected waves that cause such interference are generated all around the edge, and the distance Δl is constant all around the edge, so in the case of a sound wave of a certain frequency, due to the reflection all around the edge, This has the disadvantage that sound pressure peaks or dips occur, resulting in poor sound pressure frequency characteristics.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional drawbacks, and an object of the present invention is to provide a composite speaker that can obtain excellent sound pressure frequency characteristics without causing interference due to the reflection of sound waves at the edges. shall be.

Structure of the Invention In order to achieve the above object, the composite speaker of the present invention comprises: a speaker for reproducing mid-low tones having at least one annular plane diaphragm; a speaker for reproducing mid-to-high tones provided in a hollow part of the speaker for reproducing mid-to-low tones; , a substantially truncated cone-shaped or substantially polygonal truncated pyramid-shaped buttful plate having a front opening surface larger than a joint surface is provided on the periphery of the mid-to-treble sound reproduction speaker; The distance from the center to the front opening end of the baffle plate is configured to vary over all or most of the periphery of the opening end, and this configuration allows for a difference between sound waves reflected by the buff full plate and sound waves directly radiated. It is possible to prevent disturbances in sound pressure due to interference.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view of a composite speaker according to an embodiment of the present invention. In the following figures, the same members as those in FIG. 1 are given the same numbers and their explanations will be omitted.

In FIG. 2, reference numeral 13 denotes a substantially conical buff-full plate whose front opening surface is larger than the surface to be joined to the frame 5 in the peripheral portion of the speaker for reproducing medium and high-frequency sounds. Figure 3a
is a top view of this baffle plate 13, and FIG. 3b is a side view of the same. In FIGS. 3a and 3b, the center of the joint surface 13a where the buff full plate 13 joins the frame 5 coincides with the center of the diaphragm 9 of the speaker for medium and high frequency reproduction, and the front opening end of the buff full plate 13 extends from this center. The shape is a truncated cone cut diagonally so that the distance Δl to the opening end 13b is not the same over the entire circumference of the opening end 13b. (In addition, the joint surface 13
If the centers of a and the diaphragm 9 do not coincide, the configuration may be such that the distance Δl from the center of the diaphragm 9 to the opening end 13b is not the same over the entire circumference of the opening end 13b. ) The operation of this embodiment configured as above will be explained below.

First, the sound waves emitted from the medium and high frequency speakers are
A direct wave traveling on the central axis of the diaphragm 9 and a reflected wave reflected by the buffer plate 13 are generated, and the direct wave and the reflected wave interfere with each other on the central axis. At this time, since the distance Δl from the center of the diaphragm 13 to the open end 13b differs over the entire circumference, the frequency at which the sound pressure is disturbed due to interference differs over the entire circumference. In other words, for sound waves of a certain frequency, the influence of reflected waves can be considered to be almost negligible because the distance Δl changes gradually over the entire circumference, and the on-axis sound pressure caused by interference can be considered to be negligible. It is possible to eliminate the disturbance of Further, since the buff-full plate 13 has a substantially truncated conical shape, the annular plane diaphragm 1 comes into contact with the buff-full plate 13, and excellent sound pressure frequency characteristics can be obtained without disturbing vibration.

In this embodiment, the baffle plate 13 has a substantially truncated conical shape, but as shown in FIG. It may be configured using a buff-full plate 15 that has an unstable shape so that the distances are different.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 6 is a sectional view of a composite speaker according to another embodiment of the present invention. In FIG. 6, reference numeral 16 denotes a speaker protection net fixed to the frames 2 and 5 so as to support and fix the baffle plate 13 and cover the upper part of the annular plane diaphragm 1, and is made of a porous thin plate or a net-like plate. has been done. With the above configuration, the full board 1
3 can improve mechanical strength, so the material may be thin paper or aluminum foil, easy to process, and can prevent abnormal noise from occurring. Furthermore, since the bass passes through the net hole 16a, it does not affect the reproduction of the bass.

By closing the holes 13a of the net corresponding to the shaped portion of the buffle plate 13, the buffle plate 13 may also serve as a protective net.

Effects of the Invention As described above, according to the composite speaker of the present invention,
Since the distance from the center of the diaphragm of the loudspeaker for medium and high frequency reproduction to the front opening end of the full plate varies over all or most of the periphery of the opening end, some of the sound waves emitted from the diaphragm are directly radiated. It is possible to obtain excellent sound pressure frequency characteristics without causing interference between the direct wave reflected by the deflection plate and the reflected wave reflected by the buff-full plate.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional composite speaker, FIG. 2 is a sectional view of a composite speaker according to an embodiment of the present invention, FIG. 4 and 5 are top views of other baffle plates, and FIG. 6 is a sectional view of a composite speaker of another embodiment. 1... Annular plane diaphragm, 5... Frame, 9...
...Vibration plate, 13, 14, 15... Batsuful plate, 1
3a...joint surface, 13b...open end.

Claims (1)

[Scope of Claims] 1. A speaker for reproducing medium and low frequencies having at least one annular flat diaphragm, a speaker for reproducing medium and high frequencies provided in a hollow part of the speaker for reproducing medium and high frequencies, and a speaker for reproducing medium and high frequencies provided in a hollow part of the speaker for reproducing medium and high frequencies. The peripheral portion includes a substantially truncated conical or substantially polygonal truncated pyramid-shaped buttful plate whose front opening surface is larger than the joint surface, and the buttful plate extends from the center of the diaphragm of the mid-to-high frequency sound reproduction speaker to the front opening of the buttful plate. A composite speaker formed such that the distance to the end varies over all or most of the circumference of the open end. 2. The composite speaker according to claim 1, wherein the double plate is supported and fixed to a porous thin plate or a mesh plate that covers the upper part of the annular plane diaphragm.