JPS5955699A - Entirely dynamic driving speaker - Google Patents

Abstract

PURPOSE:To attain the reproduction of a low frequency by arraying plural rod- like magnetic poles in parallel and with an alternately opposed polarity, arranging a diaphragm with a waveform section so as to cover the magnetic poles arrayed in parallel and then setting up a voice coil on the surface of the diaphragm between adjacent magnetic poles. CONSTITUTION:The end parts of plural magnetic poles 6, 6' consisting of a highly magnetic permeable material and arranged in parallel are coupled with both ends of a permanent magnet 7 through highly magnetic permeable supporting plates 12, 12', and for instance, the magnetic poles 6, 6' are magnetized with N and S poles respectively. On the other hand, the diaphragm 8 is held by a frame body 10 through an edge 9. The cross section of the diaphragm 8 is formed by affording a ruggedness to curve along the magnetic poles 6, 6' and each voice coil 11 is arranged between the adjacent magnetic poles 6, 6' on the surface of the diaphragm 8. The voice coils 11-1, 11-3 and 11-2, 11-4 are connected to conduct a reverse current and the diaphragm is driven in the same direction by the voice coils in all. Thus, the stiffness of an oscillation system is reduced to reproduce the low frequency and to improve the efficiency of conversion.

Description

[Detailed description of the invention] [Technical field of invention] mosquito The invention relates to an electrodynamic type full-surface driving speed N.

[Technical background of the invention]

Electrodynamic full-drive speakers drive the entire surface of the diaphragm at the same time, making it difficult for the diaphragm to cause split vibration, and therefore generally have good acoustic characteristics, and are used in some high-fidelity stereo speakers. FIG. 1 shows a cross-sectional perspective view of an example of a conventional fully driven speaker. A voice coil 2 is provided on the surface of the diaphragm 1, and the diaphragm 1 is held by a frame 3. - Several permanent magnets 4 are fixed to the frame 3 via a yoke 5.

Here, the polarity of the permanent magnet 4, the permanent magnet and the voice coil 2
If you look at the positional relationship, it will be as shown in Figure 2. That is, a pair of magnets facing each other with the diaphragm 1 in between are arranged with their magnetic poles of the same polarity facing inward, and adjacent magnets are arranged so that their polarities are opposite to each other. By doing so, it is possible to generate a magnetic field substantially parallel to the diaphragm 1, as shown by the arrow in the figure. Here, the voice coil 2 on the surface of the diaphragm 1 is placed in the above-described substantially parallel magnetic field so as to be perpendicular to the magnetic field. If a signal current is caused to flow through the voice coil with such a structure, it is possible to generate an acoustic signal corresponding to the current signal.

[Problems with background technology]

However, such speakers have the following drawbacks. That is, since it is difficult to make the magnetic field near the voice coil parallel and uniform, distortion is likely to occur particularly during large amplitude operation of bass sounds. 2. Since the structure bends the lines of magnetic force in the air, it is very difficult to increase the efficiency of the speaker because there is a lot of leakage magnetic flux and the magnetic flux cannot be used effectively.In order to ensure a certain level of efficiency, It is necessary to use a large amount of magnetic material, and the cost tends to be high. Third, since the magnetization direction of each magnet is alternately reversed, it is difficult to magnetize the magnets after assembly. Therefore, it is necessary to assemble a speaker using magnets that have already been magnetized, but because of the attractive and repulsive forces of the magnets, assembly is difficult and mass production is difficult.

[Purpose of the invention]

An object of the present invention is to provide an electrodynamic full-plane drive speaker that has high electroacoustic conversion efficiency and is less likely to generate distortion during operation during large vibrations.

[Summary of the invention]

In this invention, a plurality of magnetic poles with different polarities are alternately arranged so that a substantially parallel magnetic field is generated between adjacent magnetic poles, and the diaphragm has a cross-sectional waveform that threads through these magnetic poles. In addition, the distance between adjacent magnetic poles must be greater than the thickness of the diaphragm including the voice coil, but this thickness can usually be made very small, so the magnetic field at the gap can be made stronger. As a result of the above, it was possible to increase the conversion efficiency and reduce distortion during large amplitude operation.

[Embodiments of the invention]

Hereinafter, one embodiment of the invention will be described in detail with reference to the drawings. FIG. 3 is a cross-sectional perspective view of one embodiment of the present invention. Multiple parallel magnetic poles 6 made of high magnetic permeability material
and 6' are support plates 12 whose ends are each made of a high magnetic permeability material.
, 12' are connected to both ends of the permanent magnet 7, and the magnetic pole 6 is magnetized to the north pole, and the magnetic pole 6' is magnetized to the south pole, respectively. Although not shown, it is also possible to provide the permanent magnet 7 and the support plates 12, 12' at the other ends of the magnetic poles 6, 6'.

On the other hand, the diaphragm 8 is partially held by a frame 10 via an edge 9 made of a soft material such as urethane. As shown in the figure, the cross section of the diaphragm 8 is formed in a concave and convex manner so as to weave through the magnetic poles 6 and 6', and the voice coil 11 is arranged between the adjacent magnetic poles 6 and 6' on the surface of the diaphragm 8. Placed. The operation will be explained using FIG. As shown in the figure, for example, if the magnetic pole 6 is magnetized to the N pole and the magnetic pole 6' is magnetized to the 8 pole, the magnetic field near the voice coil will be directed to the left in the drawing at 11-1 and 11-3, and 11-2 and 11- In 4, the drawing will face right.

Therefore, voice coils 11-1°, 11-3 and 11-2
．． If the diaphragm 11-4 is connected so that the current in the opposite direction stagnates, the diaphragm will receive driving force from all the voice coils in the same direction. An example of a voice coil connection method is shown in FIG. 5. FIG. 5 is a developed view of an example of a diaphragm, and the diaphragm 8 shown in FIG. 3 is obtained by folding the portion indicated by a dotted line. Voice coil 11 has two sides, front and back! 51
At 1-a and 11-b, conduction between the front and back voice coils is established by an appropriate method such as through-hole processing or reventing. An electrical signal is applied between points 11-0 and 11-d. This diaphragm can be easily manufactured by a method similar to that used for manufacturing ordinary printed circuit boards, in which, for example, metal foil is pasted onto a plastic plate and then conductive parts are formed by etching.

〔Effect of the invention〕

By adopting the structure of this embodiment, firstly, since the diaphragm is folded, the stiffness of the vibration system can be reduced, making it possible to reproduce low frequencies. Second, since the spacing between the magnetic poles can be reduced, a magnetic circuit with less leakage magnetic flux can be achieved, and the conversion efficiency can be increased.

Thirdly, even if the spacing between the magnetic poles is reduced, the allowable amplitude of the diaphragm can be increased regardless of the spacing between the magnetic poles, making it possible to create a speaker that can withstand large amplitudes. Fourthly, unlike the conventional example, there is no need to twist the lines of magnetic force in the air, so the range of the parallel magnetic field can be widened, and in this respect too, distortion at large amplitudes can be reduced. Fifth, in this embodiment, as shown in FIG. 3, magnet 7 and another magnet placed on the opposite side (not shown) need only be magnetized in the same direction, making it easy to magnetize them after assembling the speaker. It is. Therefore, assembly is easier than in the previous embodiment. Sixth, since the diaphragm can be thicker than in the previous embodiment, it is easier to handle it as a component. Furthermore, since the lowest resonance frequency can be lowered, the bass reproduction band can be expanded.

[Other embodiments, modifications, and applications of the invention] The cross-sectional shape of the diaphragm does not need to be folded as shown in Figure 3, but may be wave-shaped as shown in Figure 6. . In this case, it is desirable that the diaphragm surface be parallel to the vibration direction in the vicinity of the voice coil, but it does not necessarily have to be parallel if (7) the design allows for a slight decrease in the conversion efficiency.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional perspective view of the conventional example, Fig. 2 is a cross-sectional view of the conventional example, Fig. 3 is a cross-sectional perspective view of the present invention, Fig. 4 is a cross-sectional view of the present invention, and Fig. 5 is a vibration of the present invention. FIG. 6 is a developed view of the plate, and FIG. 6 is a sectional view of another embodiment of the present invention. 1...[Moving plate 2...Voice coil 4...
...Magnet 6,6'...Magnetic pole 7...
... Magnet 8 ... Vibration plate 11 ...
・・Patent attorney Noriyuki Chika (and 1 other person) representing Heuscoil (8) Figure 1

Claims (4)

[Claims] (1) In a full-plane drive type speaker in which a voice coil is arranged over the entire surface of the diaphragm, a magnetic circuit is constructed by arranging a plurality of bar-shaped magnetic poles in parallel so that their polarities are alternately opposite, and these are arranged in parallel. 1. An electrodynamic full-drive speaker characterized in that a diaphragm having a corrugated cross section is arranged so as to weave through the magnetic poles, and a voice coil is arranged on the surface of the diaphragm between the adjacent magnetic poles. (2) The electrodynamic full-plane drive speaker according to claim 1, characterized in that a permanent magnet is disposed at one longitudinal end of the rod-shaped magnetic pole. (3) The electrodynamic full-plane drive speaker according to claim 1, characterized in that permanent magnets are arranged at both longitudinal ends of the rod-shaped magnetic pole. (4) The electrodynamic full-plane drive speaker according to claim 1, wherein the magnetic poles of the diaphragm and the portion between the magnetic poles are parallel to the vibration direction of the diaphragm.