JPH099392A - Speaker - Google Patents

Abstract

PURPOSE: To improve a high frequency characteristic by arranging opposite faces in the same polarity and providing a short-ring to an entire outer circumferential face of two magnets and arranging voice coils in a magnetic field of the outer circumference so as to decrease electromagnetic distortion thereby suppression impedance increase for a high frequency. CONSTITUTION: Magnets 1, 2 are arranged while their same poles are opposite to each other and voice coils are arranged in a strong repulsive magnetic field caused in an outer circumferential side. Then a short ring 4 is provided to the outer circumferential face of the magnets 1, 2, an outer circumferential part of a yoke or a spacer 3 interposed between the magnets 1, 2 is projected to be nearly mated to the outer circumferential face of the short ring 4. Through the constitution above, even when the short ring 4 is provided, no defect of decreasing magnetic flux density is not caused. Then the short ring 4 made of a nonmagnetic conductive material is provided to the outer circumference of the magnetic 1, 2 to short-circuit an eddy current generated in the magnetic circuit so as to reduce electromagnetic distortion thereby increasing the impedance of the voice coil at medium and high frequencies and improving the high frequency characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin speaker having a magnetic circuit utilizing a repulsive magnetic field.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, two thin disk-shaped or ring-shaped magnets 1 and 2 are arranged so as to face each other with a nonmagnetic spacer or a magnetic yoke 3 between them. Various types of thin speakers having the magnetic circuit have been proposed and provided. The arrows in the figure show the flow of magnetic flux, and the voice coil (not shown) is exposed to a strong repulsive magnetic field.
Are arranged to efficiently drive the voice coil and eventually the diaphragm.

In such a repulsive magnetic field type magnetic circuit, since the magnetic flux density distribution is symmetrical, the distortion caused by the driving force in the low range is also reduced, but the current distortion in the middle and high range caused by the eddy current is reduced. Requests for reduction are increasing. As a method of reducing this kind of current distortion, for example, as shown in FIG. 5, there is a method in which a non-magnetic short ring 21 is covered on the outer periphery of a so-called center pole 20 of an inner magnet type magnetic circuit. In the figure, 22 is a plate, and 23 is a magnetic gap between the plate 22 and the center pole 20. In addition, an external magnet type is also known in which a short ring is provided in the same portion.

[0004]

However, in the magnetic circuit having such a configuration, since the short ring is provided in the magnetic gap 23 between the center pole 20 and the plate 22, the magnetic gap 23 must be widened accordingly. However, there is a problem that the magnetic flux density is reduced.

The present invention has been proposed in view of the above, and an object of the present invention is to provide a loudspeaker capable of reducing the current distortion without lowering the magnetic flux density and improving the high frequency characteristics. To provide.

[0006]

SUMMARY OF THE INVENTION The present invention is a speaker in which two magnets 1 and 2 face each other with the same poles to form a magnetic circuit, and a voice coil 6 is placed in the magnetic field around the magnetic circuit. In the above, the short ring 4 is provided on the outer peripheral surfaces of the magnets 1 and 2, and the outer peripheral portion of the yoke or the spacer 3 interposed between the magnets 1 and 2 is projected to be substantially flush with the outer peripheral surface of the short ring 4. By doing so, the above object is achieved.

[0007]

In the present invention, the same poles of the magnets 1 and 2 are arranged to face each other, and the voice coil is arranged in the strong repulsive magnetic field generated on the outer peripheral side thereof. Therefore, even if the short ring is provided, there is no inconvenience that the magnetic flux density is lowered unlike the case of the magnetic circuit shown in the conventional example. Then
In the present invention, the short ring 4 made of a non-magnetic conductive material is used.
Are provided on the outer circumferences of the two magnets 1 and 2 arranged opposite to each other, whereby the eddy current generated in the magnetic circuit is short-circuited to reduce electromagnetic distortion, and the impedance rise in the mid-high range of the voice coil 6 is suppressed, thereby improving the speaker performance. The range characteristics are improved.

[0008]

FIG. 1 shows an embodiment of the present invention. 1, 2 in the figure
Are two thin disk-shaped or ring-shaped magnets that are arranged to face each other via a ring yoke or a spacer 3, and these magnets 1 and 2 are magnetized in the thickness direction and are arranged to face each other with the same polarity. , A repulsive magnetic field is generated between the facing surfaces. And as these magnets 1 and 2 which comprise a magnetic circuit, an anisotropic sintered magnet (neodymium magnet) is used, for example.

Reference numeral 4 denotes a ring-shaped non-magnetic conductive material provided on the entire outer circumference of each magnet 1, 2 and is generally called a short ring. This material is gold,
Appropriate ones such as silver, copper, aluminum are adopted,
Further, the thickness of the magnets 1 and 2 is appropriately selected as required.

In the magnetic circuit of the speaker, electromagnetic distortion occurs due to the non-linearity of the magnetic permeability due to the material, and it has been known to use a short ring as a measure for improving this adverse effect. Therefore, as a method of using the conventional dynamic type speaker, a method of covering the pole piece of the magnetic circuit with a short ring is generally used. In this case,
The magnetic flux density decreases.

In the present invention, in the so-called double magnet type magnetic circuit utilizing the repulsive magnetic field, attention is paid to the fact that a strong magnetic field is obtained around the outer circumference of the magnets 1 and 2 and the magnetic flux density is not reduced. 1,2
A short ring 4 is provided on the entire outer circumference of the magnetic field to short-circuit the eddy current generated in the magnetic circuit and suppress the impedance rise in the middle-high range. In this case, the outer peripheral surface of the short ring 4 and the outer peripheral surface of the yoke or the spacer 3 are substantially flush with each other.

FIG. 3 shows an example of a speaker provided with the magnetic circuit of the present invention. In this example, a yokeless type is used in which two magnets 1 and 2 are opposed to each other with a spacer 3 sandwiched therebetween, in order to reduce the thickness and weight of the magnetic circuit. However, instead of the spacer 3, a yoke is used. It may be the one you had.

In the figure, reference numeral 5 denotes a substantially bowl-shaped frame having a window 5a. The magnets 1 and 2 forming a magnetic circuit are arranged at substantially the center of the frame 5 and the repulsive magnetic field around the magnets 1 and 2 is disposed. A voice coil 6 is provided.

An inner peripheral portion of a cone-shaped diaphragm 7 is coupled to a central portion of the outer periphery of the voice coil 6, and an outer end portion of the diaphragm 7 is connected to an outer peripheral portion of the frame 5 via an edge 8. ing.

Further, a sub cone 9 having a small diameter and a conical shape is provided in the center portion on the front side of the diaphragm 7. The neck of the inner peripheral portion of the sub-cone 9 is connected to the outer periphery of the voice coil 6, and the center portion 10 of the sub-cone 9 is provided with a dust-proof center cap 10. An inner peripheral portion of the damper 11 is connected to a substantially central portion of the outer periphery of the voice coil 6, and an outer peripheral portion of the damper 11 is connected to a supporting portion 5b formed of a step portion formed on the frame 5. Further, the magnetic circuit is fixed on a supporting portion 5c formed of a convex step portion formed in the center of the bottom portion of the frame 5 to form a speaker,
Of course, the above magnetic circuit can also be applied to other planar speakers.

FIG. 3 shows impedance characteristics with respect to frequency. In the figure, a is the present invention, and b is a conventional example without the short ring 4. According to the present invention, the impedance rise can be suppressed and the mid-high range characteristics can be improved.

[0017]

As described above, according to the present invention, in the speaker in which the facing surfaces of the two magnets 1 and 2 are arranged with the same pole, and the voice coil 6 is arranged in the magnetic field on the outer periphery thereof, Since the short ring 4 is provided on the entire outer circumferences of 1 and 2 to reduce the electromagnetic distortion, there is an effect that the impedance rise in the high frequency band is suppressed and the high frequency band characteristic is improved.

[Brief description of drawings]

FIG. 1 is a schematic half sectional view of a magnetic circuit used in the present invention.

FIG. 2 shows an example of the speaker of the present invention.

FIG. 3 is an explanatory diagram showing impedance characteristics with respect to frequency.

FIG. 4 shows characteristics of a conventional magnetic circuit.

FIG. 5 is a cross-sectional explanatory view of a conventional inner magnet type speaker including a short ring.

[Explanation of symbols]

 1, 2 magnet 3 yoke or spacer 4 short ring 5 frame 6 voice coil 7 diaphragm 8 edge 9 sub-cone 10 dust-proof cap 11 damper

Claims (1)

[Claims] 1. A loudspeaker in which opposing surfaces of two magnets (1), (2) are arranged with the same pole to form a magnetic circuit, and a voice coil (6) is arranged in a magnetic field on the outer periphery thereof. A short ring (4) is provided on the outer peripheral surfaces of the magnets (1), (2), and the outer peripheral portion of a yoke or spacer (3) interposed between the magnets (1), (2) is projected.
A speaker characterized in that it is substantially flush with the outer peripheral surface of the short ring (4).