JPS6127270Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speaker equipped with a push-pull magnetic circuit and a damper mechanism configured to apply a bias.

Figure 1 shows a typical example of a conventional speaker.
In the figure, 21 is the magnet, 22 is the center pole,
23 is a plate, 24 is a voice coil, 25 is a damper, 26 is a frame, and 27 is a diaphragm, which is a so-called single-type magnetic circuit in which one voice coil is arranged in one magnetic gap. Also, the damper 25 is also single.

The above-mentioned conventional devices have the following drawbacks.

(1) Since the magnetic flux density of the magnetic circuit is asymmetrical, nonlinear distortion occurs in the speaker output as shown in the frequency characteristics of FIG. 9.

(2) The AC magnetic field of the voice coil is superimposed on the DC magnetic field of the magnetic circuit, causing nonlinear distortion in the speaker output.

(3) Since the damper is a single damper, the spring constant becomes zero when the cone (including the voice coil) is located near the center as shown in Figure 7, and there is no restoring force near the center.

(4) Since the damper is single, the force-displacement curve becomes non-linear, as shown in FIG. 7, and distortion occurs in the speaker output sound pressure.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks and provide a speaker with low distortion over the entire band.

Embodiments of the present invention will be described below based on the drawings from FIG. 2 onwards.

In the diagram, 1 is the magnet, 2 is the center pole, and 3
is the top plate, 4 is the back plate,
Two magnetic gaps 5, 5 are formed by the top plate 3 and back plate 4, and two voice coils 6, 5 are provided corresponding to both magnetic gaps, respectively.
7 are arranged to form a so-called push-pull magnetic circuit.

In this case, if the center pole 2 is simply made cylindrical, the magnetic flux imbalance 1 as shown in FIG.
9 and 20 occur, and not only does the magnetic flux imbalance 19 act on the voice coil 6 and the magnetic flux imbalance 20 acts on the voice coil 7, but also when the amplitude of the voice coil is large, the magnetic flux imbalance 1
9 is generated as a force in the opposite direction to the voice coil 7, and the magnetic flux imbalance 20 is generated as a force in the opposite direction to the voice coil 6, causing secondary distortion.

On the other hand, if the voice coils 6 and 7 are separated, inductance cancellation will be poor and third-order distortion will increase, so it is desirable to have the voice coils 6 and 7 as close as possible. In this case, if the center pole 2 has a cylindrical shape, the above-mentioned disadvantages become even more severe.

Therefore, in the embodiment of the present invention, the center pole 2
A small diameter portion 2a is formed with the midsection having a small diameter, so that the width of the tip of the magnetic pole portion corresponds to the width of the top plate and the back plate. This eliminates magnetic flux imbalance and therefore has no adverse effect on the voice coil. In the figure, 8 is a center pole holder, 9 is a frame, 10 is a diaphragm, and 11 is a bobbin.

By configuring as described above, the nonlinearity caused by the magnetic circuit is reduced, and the above-mentioned conventional disadvantages (1) and (2), which are distortions caused by the magnetic circuit, are improved. Even when using the frequency characteristics shown in FIG. 9, the frequency characteristics shown in FIG. 9 become as shown in FIG. 10, and distortion in the middle and high ranges is reduced.

A damper mounting portion 9a is provided around the inner side of the frame 9, and the outer circumferential surface of a damper 12, which will be described below, is attached to the damper mounting portion 9a.

The damper 12 is composed of two upper and lower damper members 13 and 14 of the same shape, and both damper members are stretched so as to separate from each other toward the outer end. The structure of the damper member,
Various shapes can be considered, and FIGS. 4 to 6 show examples thereof. Fig. 4 shows a wave damper, Fig. 5 shows a butterfly damper, and Fig. 6 shows a damper suspended using strings. 15 maintains the distance between the outer peripheral ends of both damper members 13 and 14, and the damper mounting portion 9
This is a spacer to make it easier to fix to a.

In the damper 12 configured as described above, the two upper and lower damper members 13 and 14 are in a state of tension with each other, and become a push-pull damper in which a bias of force and displacement is always applied. There is. Theoretical equations for the force F and displacement x in the vibration direction of this damper are shown below in comparison with a conventional single damper (however, this equation corresponds to a string damper).

k...spring constant in the direction of the damper center, a...width of the damper, b...preliminary displacement (bias amount) of the damper, in the case of a conventional single damper Therefore, the curve shown in FIG. 7 is obtained.

For push pull damper This results in the state shown in FIG.

In the push-pull damper as described above, linearity is good over the entire amplitude, and the conventional drawbacks (3) and (4) due to non-linearity of the damper can be improved.

In the speaker configured as described above, distortion can be improved over the entire band as shown in FIG.

According to the speaker of the present invention, distortion caused by the nonlinearity of the magnetic circuit can be improved, and distortion caused by the nonlinearity of the damper can be improved at the same time, thereby obtaining a speaker with low distortion over the entire band. be able to.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional speaker, Figs. 2 to 11 are drawings for explaining embodiments of the speaker according to the present invention, Fig. 2 is a sectional view, and Fig. 3 shows a center pole. An enlarged sectional view showing the magnetic flux imbalance in the case of a cylindrical shape, Figures 4 to 6 are perspective views showing an example of a push-pull damper, and Figure 7 is a graph showing the force-displacement characteristics of a conventional single damper. , Fig. 8 is a graph showing the force-displacement characteristics of a push-pull damper, Figs. A frequency characteristic diagram when a single damper is used in the push-pull magnetic circuit according to the invention. FIG. 11 is a frequency characteristic diagram of the speaker according to the invention. 1... Magnet, 2... Center pole, 3
...Top plate, 4...Back plate, 5
...Magnetic gap, 6,7...Voice coil, 8
...Center pole holder, 9...Frame,
10... Vibration plate, 11... Bobbin, 12... Damper, 13, 14... Damper member.

Claims (1)

[Scope of utility model registration request] Two magnetic gaps are formed by the top plate and the back plate, and two voice coils are arranged to correspond to both magnetic gaps, respectively.The damper that supports the voice coils is formed by two damper members having the same shape. 1. A speaker characterized in that both damper members are stretched so as to be separated from each other toward the outer end.