JPH04115698A - Flat speaker - Google Patents

Abstract

PURPOSE:To expand a reproduction band by making a magnet made by sintering or casting or the like and having an anisotropy in the radial direction composite with a flat diaphragm and providing two voice coils with a large diameter and a small diameter to the speaker. CONSTITUTION:A magnet 18 made by sintering or casting or the like and having an anisotropy in the radial direction is fitted to an upper outer side of a yoke 16 by an adhesives to form an outer magnetic circuit. Moreover, a magnet 19 made by sintering or casting or the like and having an anisotropy in the radial direction forming an inner magnetic circuit is fitted to an outer peripheral surface at the upper part of a center pole of a plate 17. Then a perpendicularly bended fixed part 24 of a large diameter voice coil bobbin 26 is fixed to a lower face of a flat diaphragm 21 and a perpendicularly bended fixed part 25 folded of a small diameter voice coil bobbin 27 is fixed to a lower face of the flat diaphragm 21. Then a node circle caused by a primary resonance is driven by a large diameter voice coil 28, and a node circle caused by a secondary resonance is driven by a small diameter voice coil 29. Thus, the reproduction band is expanded up to a frequency at which a ternary resonance takes place.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flat speaker whose reproduction band can be expanded by driving a flat diaphragm in a double-node manner.

BACKGROUND OF THE INVENTION First, a conventional flat plate speaker of this type will be explained along with a third one.

In Fig. 3, 1 is a plate with a center ball 2 integrally formed in the center of the upper surface, 3 is an annular magnet fixed on the plate 1, and 4 is an annular upper plate fixed on the upper surface of the magnet 3. An annular magnetic gap is formed between the inner peripheral surface of the upper plate 4 and the outer peripheral surface of the center ball 2. 5 is a frame fixed to the upper plate 4; 6 is a circular flat plate diaphragm; this flat plate diaphragm 6 is supported by the frame 5 via an edge member 7. 8 is a gasket. Reference numeral 9 denotes a conical cylindrical drive cone fixed to the lower surface of the flat diaphragm 6, and the large diameter end of the drive cone 9 is bent to form the cylindrical portion 1.
0 is formed, and a fixing part 11 is formed which is bent at right angles to the cylindrical part lO, and this fixing part 11 is fixed to the lower surface of the flat diaphragm 6. 12 is a cylindrical voice coil coil bobbin fixed to the small diameter end of the drive cone 9;
A voice coil 13 is wound around. 14 is a damper that supports the voice coil coil bobbin 12.

The location where the drive cone 9 is fixed to the flat diaphragm 6 is a nodal portion generated by the primary resonance of the flat diaphragm 6, and the drive cone 9 is fixed to the nodal portion of the flat diaphragm 6 in this way. When the nodal portion is driven by the oscillator, the first resonance is eliminated and the reproduction band is expanded to a frequency at which the second resonance occurs. The reason why the cylindrical portion 10 is provided in the drive cone 9 is that the primary resonance cannot be completely eliminated unless the nodal portion of the flat diaphragm 6 is driven in a direction perpendicular to the flat diaphragm 6. It is.

Problems to be Solved by the Invention In the above-mentioned conventional flat plate speaker, only the nodal portion produced by the primary resonance is driven, the primary resonance is removed, and the reproduction band is limited to the frequency at which the secondary resonance occurs. Since it is not expanded, there is a drawback that it is not possible to reproduce up to the frequency at which third-order resonance occurs.

In FIG. 4, the solid line is the sound pressure frequency characteristic of a flat plate speaker that is not driven by nodes, and a peak occurs at frequency fh above the sound pressure frequency. In the conventional example, when the nodal part generated by the first resonance is driven as shown by the dotted line, the first resonance is removed and reproduction is performed up to the frequency fat at which the second resonance occurs, but the third resonance It had the disadvantage that it could not reproduce frequencies up to the point at which resonance occurred.

SUMMARY OF THE INVENTION An object of the present invention is to provide a flat speaker that eliminates the above-mentioned drawbacks of the conventional loudspeaker and expands the reproduction band to a frequency at which third-order resonance occurs.

Means for Solving the Problems In order to solve the above problems, the present invention combines the above-described flat plate diaphragm with a magnet having anisotropy in the radial direction made by sintering or casting, etc. It consists of two voice coils, one caliber and the other small caliber.

Effect With the above configuration, a magnetic circuit is constructed using magnets having anisotropy in the radial direction, and a large-diameter voice coil drives the nodal portion caused by the primary resonance, thereby eliminating the primary resonance. can be reproduced up to the frequency where the second resonance occurs.
A small-diameter voice coil drives the nodal portion caused by the second-order resonance, and the reproduction band can be expanded to a frequency at which the second-order resonance is eliminated and the third-order resonance occurs.

Embodiment Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a structural diagram of an example according to the present invention.

As shown in Figure 1, 15 is a yoke that constitutes the outer magnetic circuit, and 16 is a yoke with an integrated center pole that constitutes the outer magnetic circuit, and also serves as the yoke that constitutes the inner magnetic circuit. . Reference numeral 17 denotes a plate integrated with the center pole that constitutes the inner magnetic circuit. York 15. York 16. Plate 17 is fixed with adhesive.

A magnet 18 is made by sintering or casting and has anisotropy in the radial direction, and is fixed to the outside of the upper part of the yoke 16 with adhesive to form an outside magnetic circuit. A magnet 19 constituting an inner magnetic circuit is attached to the outer peripheral surface of the upper part of the center pole of the plate 17, and is made by sintering or casting and has anisotropy in the radial direction.

20 is a frame fixed to the yoke 15; 21 is a circular flat plate diaphragm; this flat plate diaphragm 21 is supported by the frame 20 via an edge member 22; 2
3 is a gasket. 26 is a large-diameter voice coil bobbin, and a fixed part 24 bent at right angles is fixed to the lower surface of the flat diaphragm 21. A voice coil 28 is wound around this voice coil bobbin 26. 30 is a damper that supports the voice coil bobbin 26. 27 is a small-diameter voice coil bobbin, and the fixing part 25 is bent at a right angle.
is fixed to the lower surface of the flat diaphragm 21. The direction in which it is bent at right angles is bent so that it becomes a nodal part due to resonance. A voice coil 29 is wound around this small diameter voice coil bobbin 27. 31 is a damper that supports the voice coil bobbin 27.

As described above, the present invention configures a magnetic circuit with magnets 18 and 19 having anisotropy in the radial direction, and drives the nodal portion caused by the primary resonance with a large-diameter voice coil. The first-order resonance is removed and reproduction can be performed up to the frequency at which the second-order resonance occurs. In Fig. 2, the dotted line indicates that the conventional example can only reproduce up to the second-order resonance frequency, and the second-order resonance frequency ft
A peak occurs at . The small-diameter voice coil 29 drives the inside of the node caused by the second-order resonance, and as shown by the solid line in Figure 2, the second-order resonance is eliminated and the reproduction band is expanded to the frequency at which the third-order resonance occurs. This means that it is possible to provide a speaker that can reproduce a wide range of reproduction frequencies from the speaker.

Since the flat speaker of the present invention is configured as described above,
The first-order resonance and the second-order resonance can be removed, the reproduction band can be expanded to the frequency where the third-order resonance occurs, and an extremely wide band can be reproduced, which is of great industrial value.

[Brief explanation of drawings]

Fig. 1 is a half-sectional view showing an embodiment of a flat plate speaker based on the present invention, Fig. 2 is a comparison characteristic diagram of sound pressure frequency characteristics of the present invention and a conventional flat plate speaker, and Fig. 3 is a characteristic diagram of a conventional flat plate speaker. FIG. 4, which is a half-sectional view of a flat plate speaker, is a sound pressure frequency characteristic diagram of a speaker that is not driven by a node and a speaker that drives the inside of the node generated by the primary resonance. 15...Yoke, 16...Yoke of one center ball, 17...Plate, 18...
...Magnet with anisotropy in the radial direction, 19...
...Magnet with anisotropy in the radial direction, 20...
... Frame, 21 ... Circular flat plate diaphragm,
22...Edge member, 23...Gasket, 24...Fixed part, 25...Fixed part, 26...Large diameter voice Coil bobbin, 2
7...Small diameter voice coil bobbin, 28...
...Voice coil, 29.Old...Voice coil, 3
0...Dumper, 31...Name of Dumper's agent Patent attorney Akira Okaji and 2 others +5. /7
---Magnet π-Frame 21 with yoke 7- Circular joyfulness

Claims (1)

[Claims] A circular flat diaphragm is supported by a frame via an edge member, and a large-diameter and small-diameter voice coil is fitted with a composite magnet made of sintered or cast material with radial anisotropy. Equipped with a magnetic circuit with two magnetic gaps, the large-diameter voice coil drives the nodal section generated by the primary resonance of the circular flat plate diaphragm, and the small-diameter voice coil drives the circular flat plate vibration. A flat plate speaker in which both voice coils are coupled to a flat plate diaphragm so as to drive a nodal section generated by the plate's secondary resonance.