JPS6248898A - Speaker - Google Patents

Abstract

PURPOSE:To obtain a good frequency characteristic over a wide band area by providing a square irregular part at the center part of a diaphragm and driving the node of divided vibration generated in the diaphragm. CONSTITUTION:A square projected part 1 is press-worked at the center of a square diaphragm 16 made up of a metal plate, an organic macromolecule material or a sheet of paper. Also, the periphery of the diaphragm 16 is bent, a rib 22 being formed. By the forming of the square projecting part causes the increasing of the rigidity of the diaphragm and the raising of a mode frequency. Therefore, the preparation of a thin plate is sufficiently complete. Also so that the node of the divided vibration at a prescribed mode becomes circular, a voice coil, the cross section of which is circular, can be fixed at the node. By constituting the device in such a way, an unnecessary mode can be negated and a speaker having a good frequency characteristic over the wide band area can be obtained, raising the rigidity of the diaphragm by the rib 22 and preventing a trembling.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a speaker suitable for use particularly as a high frequency speaker.

[4 Summary of the Invention] This invention provides a speaker particularly suitable for use as a high-frequency speaker, in which square irregularities are formed in the center of a diaphragm to provide rigidity, and the nodes of split vibration caused by the irregularities are prevented. By driving a circle, high sensitivity and good frequency characteristics can be obtained.

[Conventional technology]

The shape of the diaphragm of conventional speakers has been cone-shaped or dome-shaped. However, in a speaker having a diaphragm having such a shape, acoustic resonance occurs due to the shape, causing disturbances in frequency characteristics. Therefore, a flat plate speaker has been proposed in which a square flat plate diaphragm is used as the diaphragm, and by driving nodes of divided vibration generated in the diaphragm, good frequency characteristics can be obtained over a wide band.

Incidentally, speakers using flat diaphragms are required to have very high rigidity as the diaphragm. It is difficult to construct such a highly rigid diaphragm with a single plate diaphragm. That is, the resonance frequency fnm of the flat plate diaphragm when the flat plate diaphragm is composed of one plate is shown as follows.

D: Bending rigidity, E: Young's modulus, h: Plate thickness: Boisson's ratio, a: One side of the diaphragm square σ: Area density = ζh,
ζ: Density, λnm: Shape of the diaphragm. Wave number parameter determined by the mode order of the boundary condition. It is necessary to reduce σ. In order to increase bending rigidity, (2)
As can be seen from the formula, the Young's modulus E must be increased and the plate thickness must be increased.

Therefore, in conventional flat speakers, the 18th diaphragm is used as the diaphragm.
As shown in the figure, skin materials 31 and 32 are placed on both sides of the core material 30.
A honeycomb sandwich structure with laminated layers was used. This honeycomb sandwich structure diaphragm has 1
It is extremely rigid compared to a single plate diaphragm.

[Problem that the invention seeks to solve]

However, the honeycomb sand inch structure diaphragm is expensive and heavy. For this reason, there is a problem in that the sensitivity is not good, especially when used as a high frequency speaker.

Therefore, an object of the present invention is to provide an inexpensive speaker that has high sensitivity (and good frequency characteristics) and is particularly suitable for use as a high-frequency speaker.

[Means for solving problems]

This invention forms square irregularities in the center of the diaphragm,
This speaker is characterized in that the nodes of divided vibration of the diaphragm generated by the rectangular irregularities are driven.

[Effect]

Forming irregularities on the diaphragm increases the rigidity of the diaphragm due to the shape effect. Therefore, a lightweight diaphragm can be used. If square irregularities are formed in the center of the diaphragm, the nodes of divided vibration will be circular. By driving the nodes of this divided vibration, unnecessary modes can be removed.

〔Example〕

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

The rigidity of the diaphragm can be increased by shape effects.

That is, as shown in FIGS. 2 to 4, by forming various irregularities in the center of the diaphragm 1, the rigidity of the diaphragm 1 can be increased due to the shape effect. In FIG. 2, a square convex portion 2 is formed in the center of a square diaphragm 1. FIG. 3 shows a square diaphragm 1 in which a diamond-shaped protrusion 3 is formed in the center. In FIG. 4, a circular convex portion 4 is formed in the center of a square diaphragm l. In addition to the above, various shapes of unevenness may be formed on the diaphragm 1. In addition, as shown in FIG. 5, the diaphragm 1
The rigidity of the diaphragm can also be increased by forming a square or circular recess 6 in the center of the diaphragm.

Further, as shown in FIG. 6, by bending the outer periphery of the diaphragm 1 and forming ribs 5 on the outer periphery of the diaphragm 1, the 2i11 properties of the diaphragm 1 can be improved. In addition, in FIGS. 5 and 6, 7 indicates a voice coil, and 8 indicates an edge. Furthermore, as shown in FIG. 7, by forming a plurality of ribs 10 extending from the convex portion 9 formed at the center of the diaphragm 1 to the outer circumference of the diaphragm 1, the β111 property of the diaphragm 1 can be reduced. can be raised.

In this way, if the oscillation properties of the diaphragm can be increased, the mode frequency can be improved.

As a result, a thin single plate can be used as the diaphragm, and the weight of the diaphragm can be reduced.

Furthermore, by driving the divided vibration nodes of the diaphragm that has such a shape effect, unnecessary modes can be canceled out.

The modes that may appear when driven point-symmetrically with the center of the diaphragm as a starting point are shown in Figures 8A to 8G in the case of a square homogeneous flat plate diaphragm. This is the mode shown. These modes cause peaks and dips in the frequency characteristics.

When the diaphragm is flat and homogeneous, fI:l
The l+ mode is circular. However, if the diaphragm is given a three-dimensional shape in order to increase the rigidity of the diaphragm due to shape effects, the nodes of the divided vibrations will not necessarily be circular due to the shape of the diaphragm, and the shape of the nodes of the divided vibrations will change. It changes in various ways. Therefore, in order to investigate the relationship between the shape of the diaphragm and the shape of the nodes of divided vibration, the inventors of the present application conducted simulations of diaphragms of various shapes using the finite element method.

9 to 17 show these simulation models and their results. FIG. 9 shows the element division of the basic model without the shape effects used in the simulation. FIG. 1O shows the simulation results in f0 mode analyzed using this basic model, and FIG. 11 shows the simulation results in fi13 mode. r at this time. The mode frequency is 623
Hz, the frequency of f 1311 mode is 1939Hz
It is. As shown in FIG. 11, nodes (indicated by black dots) in the flff3□ mode appear in a circular shape.

FIG. 12 shows element division in the case where a square convex portion is formed at the center used in the simulation.

Figure 13 shows the simulation run results in f0 mode analyzed using this element division, and Figure 14 shows f 133
1 shows simulation results in one mode.

f at this time. The frequency of 1,000-1· is 66611z, and f
The frequency of the l:131 mode was 451511z.

As shown in FIG. 14, nodes in f1331 mode appear circular.

FIG. 15 shows element division when a circular convex portion is formed at the center used in the simulation. FIG. 16 shows a simulation run result in f0 mode analyzed using this element division, and FIG. 17 shows a simulation result in f1331 mode. f at this time. The frequency of the mode was 6671+z and the frequency of the f 1ffl mode was 402111z. As shown in FIG. 17, nodes in the fl:131 mode appear in a diamond shape.

As is clear from the simulation results mentioned above, by forming a square convex portion in the center of the diaphragm, the mode frequency can be increased and f 1111
The node in the mode is circular (FIG. 14), and a voice coil with a circular cross section can be used to drive this node.

FIG. 1 shows an embodiment of the present invention.

In this embodiment, based on the above-mentioned simulation results, a diaphragm having a square convex portion formed in the center is used as the diaphragm.

In FIG. 1, 8 and 11 are cylindrical center poles formed from the center of the plate 14, 12 is a ring-shaped magnet, and 13 is a ring-shaped top plate. A magnet 12 is laminated on a plate 14 having a center pole 11 formed in the center thereof, and a top plate 13 is laminated on the magnet 12. A frame 15 is fixed to the plate 13.

These center balls! 1. Magnent 12. Top plate 13. The plate 14 constitutes a magnetic circuit.

1G is a square diaphragm. As the diaphragm 16, a lightweight metal plate such as aluminum or titanium is used. As this diaphragm 16, organic polymeric material such as polyester film, paper, etc. may be used. A square convex portion 21 is formed at the center of the diaphragm 16 by press working. Further, the periphery of the diaphragm 16 is bent to form ribs 22.

A voice coil bobbin 17, around which a voice coil 18 is wound, is attached to the divided vibration nodes of the diaphragm 16.

A voice coil 18 is inserted into the magnetic gear knob of 3'1.
The peripheral edge of frame 15 is connected to f5i1 of frame 15 through edge 19.
Attached to the edges. Voice coil bobbin 17 and frame 1
A damper 20 is interposed between the damper 5 and the damper 20.

As the diaphragm 16, one in which a square convex portion 21 is formed in the center of the diaphragm 16 is used. For this reason,
The rigidity of the diaphragm 16 can be increased due to the shape effect. In addition, by forming the square convex portion 21, it is possible to
The nodes of vibration occur in a circular manner. By attaching the point coil bobbin 17 having a circular cross section to the nodes of this circular divided vibration, unnecessary modes are canceled out. Furthermore, ribs 22 are formed around the diaphragm 16. The ribs 22 increase the rigidity of the diaphragm 6 and prevent it from shaking.

〔Effect of the invention〕

According to this invention, since the diaphragm is formed with unevenness, the rigidity of the diaphragm can be increased.

Therefore, high rigidity can be obtained even if a single-plate diaphragm is used without using a honeycomb sandwich structure diaphragm, and the high-frequency limit frequency can be increased. As a result, the weight of the diaphragm can be reduced, high sensitivity can be obtained even in high-frequency speakers, and costs can be reduced.

Furthermore, since the unevenness formed on the diaphragm is square, the nodes of divided vibration occur in a circular shape. Therefore, a circular voice coil bobbin can be fixed to the node of the divided vibration, and the node of the divided vibration can be driven.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an embodiment of the present invention, Figs. 2 to 4 are front views and plan views used to explain the shape effect, and Figs. 5 and 6 are sectional views used to explain the shape effect. , Fig. 7 is a plan view used to explain the shape effect, Fig. 8 is a route map showing the generation mode, Figs. 9 to 17 are route diagrams used to explain the generation of the mode, and Fig. 18 is a conventional speaker. FIG. 2 is a perspective view used to explain the honeycomb sandwich structure used in the diaphragm of . Explanation of main symbols in the drawings 1.16: Diaphragm, 2, 3, 4.21: Convex portion. Agent Patent Attorney Tadashi Sugiura Tomo-1 bone 1 Fig. 1 Fig. 2 Fig. 3 Rib 0 Drinking river Fig. 6vA Fig. 7 Fig. 18 f + 3 mo ￥ bIt-s
f33:a-1! 'Figure 8A Figure 8B
Figure 8C %f51 is also -p Figure 8D
Figure 8E f13317-Lss+also-pFigure 8F
Fig.8

Claims (1)

[Claims] A speaker characterized in that a rectangular unevenness is formed in the center of a diaphragm, and nodes of divided vibration of the diaphragm caused by the rectangular unevenness are driven.