JPH0623115Y2 - Flat speaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to a speaker suitable for use in a low tone of a color television receiver and the like.

Background Art and its Problems Conventionally, as a speaker for low-pitched sound, one plane diaphragm, for example, a honeycomb sandwitch structure is driven by, for example, four electrokinetic drive sources, and a multipoint drive electrokinetic type as shown in FIG. Speakers have been proposed.

That is, in FIG. 1, (1) is a frame, (2) is a diaphragm,
(3) is a damper, (4a), (4b), (4c) and (4d) are diaphragms (2)
Four drive sources, one drive source (4a), (4b),
(4c) and (4d) have the same configuration. The drive sources (4a), (4b), (4c), (4d) are configured to form an external magnet type magnetic circuit as shown in FIG. 2, (5) is an annular permanent magnet, and (6) Is a pole piece, (7) is a disk-shaped magnetic yoke, (8)
Is a magnetic pole formed of a magnetic material in an annular shape, and this magnetic circuit is composed of a permanent magnet (5), a magnetic pole (8), a magnetic gap between the magnetic pole (8) and the pole piece (6), and a pole piece ( 6), a disk-shaped magnetic yoke (7). The magnetic gear between the magnetic pole (8) and the pole piece (6) has a diaphragm (2) at one end.
The voice coil (10) wound around the other end of the bobbin (9) fixed to the above is arranged.

For such a conventional multi-point drive type speaker, the drive source (4a),
(4b), (4c) and (4d) are magnetic circuit permanent magnets, respectively, and (5), (5), (5) and (5) are, for example, the north pole in the front and the rear, for example, S. Selected to be the pole. Therefore, the leakage flux from the four permanent magnets (5), (5), (5) and (5) also becomes large, and the leakage flux of this conventional speaker is relatively large as shown by the curve a in FIG. It was a big one. When such a speaker is arranged near a picture tube of a color television receiver, there is a disadvantage that leakage magnetic flux from the speaker causes mislanding or the like which affects scanning of an electron beam of the picture tube. Further, in this case, it is possible to provide a magnetic shield so that the magnetic flux leaking from the speaker does not leak to the outside, but providing this magnetic shield has a disadvantage that the structure becomes complicated and the cost becomes higher.

DISCLOSURE OF THE INVENTION In view of this point, the present invention aims to reduce the leakage magnetic flux to the outside in the above-mentioned multi-point drive type speaker.

SUMMARY OF THE INVENTION In the present invention, in a planar speaker having a plurality of driving sources for vibrating a diaphragm, the polarities of adjacent annular permanent magnets with a predetermined gap are made to be opposite to each other so that leakage flux to the outside is reduced. It is a thing.

Embodiment An embodiment of the speaker of the present invention will be described below with reference to FIG. In FIG. 3, parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this example, as shown in FIG. 1, a plane vibration plate such as a honeycomb sandwitch structure (2) is provided with four electrodynamic drive sources (4
a), (4b), (4c) and (4d), and in this example, a part of each magnetic circuit of the adjacent electromotive type drive sources is constructed as shown in FIG. The polarities of the ring-shaped permanent magnets are reversed. More specifically, drive sources (4a) and (4d)
As shown in FIG. 3, the magnetic poles of the permanent magnets (5) and (5) constituting the respective magnetic circuits are arranged so that the front is the N pole and the rear is the S pole, and the drive sources (4a) and The magnetic poles of the permanent magnets (5a) and (5a) forming the magnetic circuits of (4d) and the driving sources (4b) and (4c) adjacent to each other are S poles in the front and N poles in the back. To do so.

In this case, each voice coil (10) (10) of the drive source (4a) (4d)
The phases of the audio signal supplied to the voice coil and the audio signal supplied to the respective voice coils of the driving sources (4b) and (4c) are set to have opposite phases. In this example, the others are configured in the same manner as in FIGS. 1 and 2.

In the speaker according to this example, the first
It operates well as the speaker shown in FIGS.

Further, in this example, the polarities of the permanent magnets (5), (5), (5a), (5a) of the driving sources (4a), (4d), (4b), (4c) adjacent to each other are mutually opposite. Since they are reversed, the permanent magnets (5) (5) and (5
a) (5a) and the direction of the magnetic flux φ generated by are opposite to each other and are absorbed by the permanent magnets of the driving sources adjacent to each other,
The leakage magnetic flux of the magnetic flux φ leaking outward from the speaker is greatly reduced as shown by the broken line b in FIG.

Therefore, according to this example, since the leakage magnetic flux is greatly reduced, there is an advantage that the landing of the electron beam is not affected even if the magnetic flux is placed near the picture tube of the color television receiver. Further, since the leakage magnetic flux to the outside is reduced in this way, even if a magnetic shield is provided, a very simple one is sufficient. Moreover, in the conventional loudspeaker as shown in FIGS. 1 and 2, it is sufficient to select the magnetization direction of the permanent magnet without changing the structure thereof. Therefore, by adopting the configuration of this example, It does not complicate the configuration of the speaker.

In the above embodiment, an example in which four driving sources are provided has been described, but the polarities of the annular permanent magnets forming a part of the magnetic circuit of the driving sources adjacent to each other are provided. It can be easily understood that the same effect as that of the above-described embodiment can be obtained by reversing it. Further, in the above-mentioned embodiment, an example using a plane diaphragm is described, but it goes without saying that a cone type diaphragm may be used instead. Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

Effect of the Invention According to the present invention, it is possible to reduce the leakage magnetic flux to the outside in a multi-point drive type speaker with a simple configuration. Therefore, the speaker according to the present invention can be arranged near the picture tube of the television receiver, and there is an advantage that the stereo broadcasting due to the audio multiplexing can be reproduced well.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a multi-point drive type speaker, FIG. 2 is a cross-sectional view showing an example of a conventional multi-point drive type speaker, and FIG. 3 is a cross-sectional view showing an embodiment of the speaker of the present invention. FIG. 4 is a diagram for explaining the present invention. (1) is a frame, (2) is a diaphragm, (3) is a damper, (4a), (4
b), (4c) and (4d) are drive sources, and (5) and (5a) are permanent magnets.

Claims (1)

[Scope of utility model registration request] 1. A flat speaker having a plurality of driving sources for vibrating a diaphragm, a disk-shaped magnetic yoke, a pole piece erected on the magnetic yoke toward a rear surface of the diaphragm, and the pole. An annular magnetic pole that is provided on the same axis as the piece and that forms a magnetic gap with the pole piece, and an annular permanent magnet that is provided so as to be sandwiched between the magnetic yoke and the magnetic pole. And a magnetic circuit consisting of the magnetic circuit, each of the drive sources being formed by the magnetic circuit, and the polarities of the adjacent annular permanent magnets provided at a predetermined interval so as to be opposite to each other. Speaker.