JPS5953759B2 - electrodynamic speaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrodynamic speaker using a rectangular plane diaphragm, and provides an electrodynamic speaker that can obtain flat sound pressure frequency characteristics up to high frequencies.

Figures 1a and 1l) show a conventional electrodynamic speaker of this type.

In Fig. 1 a, l), 1 and 1' are yokes with center poles 2 and 2' integrally formed, respectively;
' is an annular magnet fixed on yokes 1 and 1',
4, 4' is an annular plate fixed on the magnet 3.3', and an annular plate is provided between the inner peripheral surface of this plate 4.4' and the outer peripheral surface of the center pole 2, 2'. A magnetic gap is formed.

The above two sets of magnetic circuits are fixed to the bottom surface of the frame 5.

6 is a rectangular plane diaphragm, and this rectangular plane diaphragm 6 is supported in the opening of the frame 5 by an edge member 7.

8.8' is a coil bobbin fixed to the lower surface of the diaphragm 6, voice coils 9, 9' are wound around the coil bobbins 8, 8', and the voice coils 9, 9' are inserted into the magnetic gap. has been done.

10.10' is a damper.

FIGS. 2a and 2b show vibration modes during resonance in free vibration of the rectangular plane diaphragm of the conventional speaker.

A in FIG. 2 indicates a vibration mode at the resonance frequency f1, and in this vibration mode A, two nodes A1. A2 occurs.

B in FIG. 2 indicates the vibration mode at the resonant frequency f3, and in this vibration mode B, four nodes B approximately parallel to the short side of the diaphragm 6 as shown in FIG.
1. B2. B3. B4 occurs.

In the conventional speaker shown in Fig. 1 a, l),
The coil bobbins 8, 8' are connected to the above section A1. It is fixed to the B4 section, and in this way the coil bobbins 8, 8'
If the node is driven by the resonant frequency f1. f3
As a result of damping vibration modes A and B in
As shown in the figure, no sound pressure peak occurs at the resonant frequency, and the reproduction band is expanded to a higher resonant frequency fH.

However, in the above conventional example, since the driving point for driving the diaphragm 6 is asymmetrical, there is a drawback that a dip in sound pressure occurs due to resonance at f2 between frequencies f1 and f3, as shown in FIG. Ta.

This dip in f2 occurs because the driving point of the diaphragm 6 is asymmetric, and its vibration mode is the fourth
As shown by C in the figure, this is called an asymmetric mode in which three nodes (C1, C2, C3) occur, and it worsens the flatness of the sound pressure frequency characteristic.

The present invention eliminates the above-mentioned conventional drawbacks, and one embodiment of the present invention will be described below with reference to FIG. 5.

In FIG. 5, the same parts as in the conventional example are given the same numbers.

The driving points of this embodiment are node A1 and node B4, as in the conventional example, and the coil bobbin 8' is fixed to node A1 and the coil bobbin 8 is fixed to node B4 and driven.

The feature of this embodiment is that 1 in the vibration mode of frequency f3.
The damping material 11 is bonded to the lower surface of the diaphragm 6 between the mounting position of the coil bobbin 8 that drives the two nodes B4 and the center of the diaphragm 6.

This bonding point is the asymmetric mode caused by asymmetric drive,
That is, vibration mode C at f2 as shown in FIG.
This is the point where the amplitude of is maximum.

As in this embodiment, when the damping material 11 having a large internal loss such as rubber is bonded, the resonance energy at the frequency f2 is absorbed, the resonance is damped, and the frequency f2 is reduced as shown in FIG. This eliminates the dip in , and provides a flat sound pressure frequency characteristic.

FIG. 7 shows another embodiment of the invention.

In this embodiment, the damping material 11 is attached to the end of the coil bobbin 8' side attached to the diaphragm 6, as in the previous embodiment.

The mounting location of the damping material 11 in FIG. 7 is also a location where the amplitude of the vibration mode at the frequency f2 shown in FIG. 4 is large.

Figures 8a and 8l) show the shape of the damping material 11 used in the speaker of the present invention.

The length l of this damping material 11 is approximately the same length as the length of the short side of the diaphragm 6.

Note that the shape of this damping material 11 is not limited to the shapes shown in FIG. It is something.

The present invention has the above configuration, and according to the present invention, a flat sound pressure frequency characteristic up to high frequencies can be obtained.

[Brief explanation of the drawing]

Figure 1a is a top view of a conventional electrodynamic speaker, Figure 1 is a sectional view of the same speaker, Figure 2a is a diagram showing the nodes of a rectangular plane diaphragm, and Figure 2 is a diagram of the same diaphragm. Figure 3 shows the vibration mode of a conventional electrodynamic speaker. Figure 4 shows the sound pressure frequency characteristics of a conventional electrodynamic speaker.
5 is a cross-sectional view of an electrodynamic speaker according to an embodiment of the present invention, FIG. 6 is a sound pressure frequency characteristic diagram of the same speaker, and FIG. The figures are side sectional views of main parts of other embodiments of the present invention, Fig. 8a,
1) is a perspective view showing an example of a damping material used in the electrodynamic speaker of the present invention. 1.1'...Yoke, 2,2'...Center pole, 3,3'...Magnet, 4,
4'...Plate, 5...Frame,
6... Rectangular plane diaphragm, 7... Edge member, 8, 8'... Coil bobbin, 9.9'.
...Voice coil, 10.10'...Damper, 11...Braking material.

Claims (1)

[Claims] 1. Among the vibration modes in the free vibration of a rectangular plane diaphragm, the first vibration mode, which produces two nodes, fixes the first coil bobbin to one node, and the second vibration produces four nodes. Fixing a second coil bobbin to one node of the mode,
In the electrodynamic speaker in which the rectangular plane diaphragm is driven at two points by the first and second coil bobbins, the first and second
An electrodynamic speaker in which a damping material is attached to a location where the amplitude of an asymmetric mode having three nodes generated in the rectangular plane diaphragm is large due to two-point driving by a coil bobbin.