JPS60171900A - Speaker - Google Patents

Abstract

PURPOSE:To flatten sound pressure frequency characteristic by arranging radially nearly polygonal cone form small diaphragms to an outer part of a dome diaphragm, driving directly the dome part with a voice coil bobbin and also driving the small diaphragms at the outer circumference. CONSTITUTION:The composite diaphragm 15 is formed by forming thermally a polyethylene synthetic fiber sheet including 30% of carbon fibers incorporatedly and arranging radially plural nearly triangle cone form small diaphragms whose apertures are connected. The diaphragm has a ridge line 15a and a valley line 15b and a position 15c being nearly 70% of the diameter of the diaphragm is deepest. The aperture of the coupling cone 16 made of aluminum is bonded to the position 15c and a voice coil bobbin 17 is connected to the other end of the coupling cone 16. A dome 18 having the same outer diameter as the diameter of the bobbin 17 is formed to the center part of the composite diaphragm 15 and the tip of the bobbin is connected to the position of the outer circumference 19 of the dome 18. The voice coil 10 is assembled in a magnetic circuit of the flat speaker.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a planar equalization type speaker.

Conventional configurations and their problems Conventionally, cone-shaped speaker diaphragms have often been used. This is because the cone shape structurally has extremely high bending strength in the vibration direction, so a wide reproduction frequency band can be easily obtained even with low elasticity materials such as paper and plastic.

However, speakers with recesses such as cone-shaped
Depending on the extent of this, peaks and dips may occur in the sound pressure frequency characteristics.

In order to solve these problems, in recent years, planar diaphragms using a honeycomb sandwich structure or the like have been studied and put into practical use.

FIG. 1 is a sectional view of a conventional flat speaker.

In Fig. 1, 1 is a yoke with a center pole 2;
3 is an annular magnet disposed on the yoke 1, and 4 is an upper plate disposed on the magnet 3, whereby the outer peripheral portion of the center pole 2 is supported by the frame 5 by an edge member 7. The open end of the coupling cone 8 is joined to the circular nodal circle a of the flat diaphragm 6, and the voice coil 1o provided at the other end is connected to the yoke 1. The center pole 2° is supported by a damper 11 for piston movement within the magnetic gap of a magnetic circuit consisting of a magnet 2, a magnet 3, and an upper plate 4. Further, the plane diaphragm 6 is, for example, a second vibration plate.
The sandwich structure shown in the figure is made of nicum as the core material. FIG. 2 is a sectional view of the NO-NICAM sandwich diaphragm. In FIG. 2, a surface material 12 made of metal foil such as aluminum is adhered to the end face of an aluminum nicum material 14 via an adhesive 13 to form a diaphragm.

However, in conventional speakers configured as described above, the planar diaphragm has a more complex structure than a paper cone, which not only increases the cost, but also increases the weight of the vibration system, which reduces the efficiency of the speaker. It had the disadvantage of lowering the

OBJECTS OF THE INVENTION The present invention solves the above-mentioned drawbacks, and provides a speaker with easily flat sound pressure frequency characteristics without using a complex flat diaphragm such as a sand char structure.

Structure of the Invention The present invention provides a composite diaphragm in which a plurality of small substantially polygonal pyramidal diaphragms are arranged radially, and the outer periphery of the diaphragm is arranged in a radial manner. The voice coil bobbin has a tip end connected to the voice coil bobbin, and a coupling cone having one end connected to the substantially polygonal pyramidal apex of all the small diaphragms and the other end connected to the abdomen of the voice coil bobbin. The concavity in the sound radiation surface of the diaphragm is much smaller than in the case of a single cone and approaches that of a flat diaphragm, so it is possible to suppress peak dips in the sound pressure frequency characteristics due to the concavity.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

Fig. 3 is a cross-sectional view of the diaphragm and vibration system of a speaker in the first embodiment of the present invention, and Fig. 4 is a plan view of the diaphragm. In Fig. 3, 15 indicates a fiber length of 0.2 to 1. A polyethylene synthetic fiber sheet containing 3° (W/W%) of carbon fiber (diameter 6 μm) is integrally thermoformed, and a plurality of small approximately triangular pyramid-shaped diaphragms with open ends connected are arranged radially. The planar shape of the composite diaphragm is shown in Fig. 4. In FIG. 4, 15a is a crest line, 15b is a valley line, and the position 15c, which corresponds to about 70% of the diameter of the diaphragm, is the deepest.

An open end of an aluminum coupling cone 16 is adhered to this position 16c, and a voice coil bobbin 17 is connected to the other end of the coupling cone 16. 18 is a composite diaphragm 1
The dome has the same outer diameter as the diameter of the voice coil bobbin 17 formed in the center of the voice coil bobbin 17.
The tip of the dome 18 is connected to the outer peripheral portion 19 of the dome 18 . The voice coil 1o is incorporated into the magnetic circuit of the planar speaker shown in FIG. Approximately 70%
Therefore, in this embodiment as well, the center of strength of the small diaphragm, that is, the driving point, is set at the same position. With this configuration, low frequency components are transmitted through the coupling cone 16
The high-frequency components are propagated over a wide range because the driving force generated in the voice coil 1o is directly propagated to the central dome. This provides a reproduction band.

FIG. 6 is a sound pressure frequency characteristic diagram showing the characteristics when the composite diaphragm of this example is manufactured into a 25 m diameter speaker. In FIG. 6, the dotted line 21 is the conventional characteristic, and the dashed line 22
indicates the characteristics of this example.

As described above, according to this embodiment, a wider reproduction band than the conventional example can be obtained, and a sound pressure higher by 1 to 1.5 dB can be obtained. This is because the weight of the vibration system of the conventional example is 32y, while the weight of this embodiment is reduced to 27y.

In this way, by dividing the composite diaphragm 16 into small diaphragms, concentrating them together, and simultaneously driving the apexes of each, that is, the center of strength, the concavity of the sound radiation surface of the composite diaphragm 16 can be made smaller than when using a single cone. Since the kana can be made smaller and closer to a flat diaphragm, it is possible to suppress the peak dip in sound pressure frequency characteristics due to depressions, and although it has a simple diaphragm structure, it has the same characteristics as a conventional flat diaphragm, or the resonance peak. In terms of suppressing the oscillation, it has better characteristics than a honeycomb flat diaphragm. In addition, in this example, since the driving force is divided into multiple small diaphragms, split resonance is less likely to occur, and the piston vibrates to a higher frequency.In addition, each small diaphragm has a shape close to a cone. Because of its shape, it has the advantage that sufficient characteristics can be obtained even when it is made of lightweight and inexpensive materials such as paper and plastics.

In this example, a composite sheet of synthetic fibers of carbon fiber and polyethylene was integrally thermoformed and used as the material, but paper made from pulp using a normal papermaking method, or thermoplastic plastic such as polyacrylate, etc. The same effect can be obtained even if the film is thermoformed by vacuum forming or the like.

Further, it goes without saying that the dome 18 at the center of the composite diaphragm 16 may be cone-shaped or rigid flat plate-shaped.

Next, a second embodiment of the present invention will be described.

FIG. 6 is a sectional view of the diaphragm and vibration system of the speaker of this embodiment. Further, the planar shape of the diaphragm is the same as that shown in FIG. 4 in the first embodiment. In Figure 6, the third
Components that are the same as those in the figures are given the same numbers. This is a composite diaphragm in which each of the slopes constituting each of the 2 small diaphragms is a curved surface. That is, in the composite diaphragm 2o, the valley line 16b shown in FIG.
In contrast to the straight line in the above embodiment, the present embodiment is characterized in that it is a curved line. 16' is a coupling cone, and the sound pressure frequency characteristics when a speaker with a diameter of 26 mm is manufactured using the composite diaphragm 2o having a configuration of 0 or more in the same manner as in the first embodiment are shown by the solid line in FIG. 23. In FIG. 7, the characteristics of this example are that the high-frequency resonance frequency is slightly lowered, but at the same time, the resonance peak is also significantly lowered.

This facilitates design when systemizing speakers. That is, according to this embodiment, when the resonance peak is high, it is possible to prevent the disadvantage that an electric circuit for peak cancellation is required, which increases the cost and deteriorates the distortion characteristics.

Effects of the Invention As described in 2., the present invention is a composite diaphragm in which small polygonal pyramidal diaphragms are arranged radially around the outer periphery of a dome-shaped diaphragm. By driving the arranged small diaphragm through the coupling cone, it is possible to create a speaker with flat sound pressure frequency characteristics, wide band, and high efficiency. Furthermore, since the diaphragm is integrally molded, it can be manufactured easily and has a significant cost reduction effect.

Moreover, by making each slope constituting the small diaphragm a curved surface and making the valley line a curved line, it is possible to obtain a speaker with a low high-frequency resonance peak. In other words, it also has the effect of facilitating system integration.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional flat speaker, FIG. 2 is a sectional view of the same diaphragm, FIG. 3 is a sectional view of the diaphragm and vibration system of the speaker in the first embodiment of the present invention, and FIG. 4 6 is a plan view of the diaphragm, FIG. 6 is a sectional view of the diaphragm and vibration system of the speaker in the second embodiment, and FIG. 6 is a sound pressure frequency characteristic diagram of the speaker in the first embodiment. FIG. 7 is a sound pressure frequency characteristic diagram of the speaker in the second embodiment. 16...Composite diaphragm, 16...Coupling cone, 17...Voice coil bobbin, 18...
···dome. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure α 6 α7 Figure 2 Figure 4 Figure 5 ? θ Fig. 6□□□□□□□] 50 100 20θ 5θD I8 2K

Claims (2)

[Claims] (1) A composite diaphragm in which a plurality of small substantially polygonal pyramidal diaphragms are arranged radially, each of which has an open end connected to the outer periphery of a dome-shaped or cone-shaped diaphragm, and a tip end is connected to the outer periphery of the diaphragm. A speaker comprising a connected voice coil bobbin, and a coupling cone having one end connected to the apex of a substantially polygonal pyramid of all the small diaphragms and the other end connected to the abdomen of the voice coil bobbin. . (2) The speaker according to claim 1, wherein each surface constituting the small diaphragm having a substantially polygonal pyramid shape is a curved surface.