JP2003018682A - Method for reducing leakage flux - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a convenient cancel permanent magnet system for demagnetizing leakage flux that the cost of a speaker system increases because a cancel permanent magnet is required. SOLUTION: The main permanent magnet 12 of a multi-way speaker 11 and the main permanent magnet 15 of a super woofer 14 are magnetized such that the lines of magnetic force are directed reversely on the side where the side face 12a of the main permanent magnet 12 faces the side face 15a of the main permanent magnet 15.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reducing magnetic flux leakage, and more particularly, to a method for reducing magnetic flux leakage in a speaker system in which a plurality of speakers are housed in one box. 2. Description of the Related Art With the spread of various video equipment and AV systems, video display equipment such as a television and a personal computer monitor and a speaker system are often used close to each other and used together. In the speaker built into the speaker system, the magnetic flux generated by the main permanent magnet that generates a magnetic field for the voice coil connected to the diaphragm leaks out of the speaker system box. In order to cause a phenomenon such as, for example, color unevenness, it is required to take measures against the phenomenon. As a simple countermeasure against this request, as shown in FIG. 3, the main permanent magnet 3 of the multi-way speaker 2 and the main permanent magnet 5 of the super woofer 4 constituting the speaker system 1 are respectively provided with main permanent magnets. The cancellation permanent magnets 6 and 7 that generate magnetic lines of force opposite to the directions of the magnetic lines of force of the magnets 3 and 5 are superimposed, and the main permanent magnet 3 and the cancellation permanent magnet 6 and the main permanent magnet 5 and the cancellation permanent magnet 7 have the same polarity. By opposing,
A cancel magnet system is known in which the magnetic lines of force do not form a loop outside the speaker system 1 and the magnetic lines of force 8 and 9 from the main permanent magnets 3 and 4 are reduced to reduce the magnetic flux leaking from the speaker system 1 to the outside. ing. However, in the above-mentioned cancel magnet system, the magnetic line of force 8 on the main permanent magnet 3 side of the magnetic lines of force generated from the magnetic poles where the main permanent magnet 3 and the cancel magnet 6 face each other is the main permanent magnet. Since a loop is formed with the other magnetic pole of the magnet 3 and the main permanent magnet 5 and the canceling permanent magnet 7 similarly create a loop of the magnetic field lines 9, the leakage flux is reduced as compared with the configuration without the canceling permanent magnet. Will remain. In addition, since the canceling permanent magnets 6 and 7 are required in addition to the main permanent magnets 3 and 5 for converting an electric signal into an oscillating motion, permanent magnets that are not directly related to the conversion function are required, which causes an increase in the price of the speaker system. It was. An object of the present invention is to provide a method capable of reducing the leakage magnetic flux while suppressing the price increase of the speaker system. [0006] In order to solve this problem, a leakage magnetic flux reduction method according to the present invention is a speaker system in which the vibration centers of a plurality of speakers are arranged substantially on a straight line. The speaker includes a main permanent magnet that generates a magnetic field with respect to the voice coil connected to the diaphragm, and sets the direction of the magnetic force lines generated by the pair of main permanent magnets of the adjacent speakers to the direction of the magnetic pole of the pair of main permanent magnets. Are magnetized in the opposite direction on the side where the side faces face. A method of reducing magnetic flux leakage according to the present invention is directed to a method of reducing the direction of lines of magnetic force generated by a pair of main permanent magnets at the facing portions of the side faces in the magnetic pole direction of adjacent main permanent magnets. Since the magnetic field lines can be canceled by the pair of main permanent magnets, the magnetic flux leakage from the speaker system to the outside can be reduced. An embodiment of the present invention will be described below with reference to FIG. In the figure, a main permanent magnet 1 of a multi-way speaker 11 constituting a speaker system 10 is shown.
2 generates a magnetic field line 13, and the main permanent magnet 15 of the super woofer 14 generates a magnetic field line 16. The direction of the magnetic lines of force 13 and 16 is changed as shown in FIG.
And 15 are magnetized so that the side faces 12a and 15a are opposite to each other. In this embodiment, the distance d between the frame 17 and the frame 18 is 1 cm. That is, the main permanent magnet 12 is magnetized so that the frame 17 side becomes an S pole,
The magnetic lines of force 13 have directions as shown in FIG. On the other hand, the main permanent magnet 15 is magnetized so that the frame 18 side becomes the N pole, and the magnetic force lines 16 of the main permanent magnet 15 are in the direction shown in FIG. When this configuration is adopted, the side surface 12a of the pair of main permanent magnets 12 and the side surface 15a of the main permanent magnet 15
The directions of the magnetic lines of force 13 and 16 on the side facing are opposite to each other, and at least the magnetic lines of force in the range where the side surface 12a of the main permanent magnet 12 and the side surface 15a of the main permanent magnet 15 shown in FIG. Leakage magnetic flux can be reduced. Next, another embodiment of the present invention will be described with reference to FIG. In the figure, a speaker system 1
9 has a main permanent magnet 21 and a cancel permanent magnet 22, and the main permanent magnet 21 generates magnetic lines of force 23 as described in the related art. Similarly, the super woofer 24 has a main permanent magnet 25 and a cancel permanent magnet 26, and the main permanent magnet 25 generates a magnetic force line 27. The direction of the magnetic force lines 23 and 27 is changed to the main permanent magnet 21 as shown in FIG.
Are magnetized so that the side surface 21a of the main permanent magnet 25 and the side surface 25a of the main permanent magnet 25 face in opposite directions. The distance between the frame 28 and the frame 29 was the same for 1 cm. That is, the main permanent magnet 21 is magnetized so that the frame 28 side becomes an S pole,
The lines of magnetic force 23 have the directions shown in FIG. On the other hand, the main permanent magnet 25 is magnetized so that the frame 29 side becomes the N pole, and the magnetic force lines 27 of the main permanent magnet 25 are in the direction shown in FIG. When this configuration is adopted, the side surface 21a of the pair of main permanent magnets 21 and the side surface 25a of the main permanent magnet 25
The directions of the magnetic lines of force 23 and 27 on the side facing are opposite to each other, and at least the magnetic lines of force in the range where the side surface 21a of the main permanent magnet 21 and the side surface 25a of the main permanent magnet 25 shown in FIG. Leakage magnetic flux can be reduced. Next, the effect of the configuration in which the magnetization direction of the main permanent magnet of the present invention is reversed (hereinafter, referred to as reverse magnetization method) is based on the leakage magnetic flux density measuring method of the Japan Electronic Machinery Association. This will be described with reference to the measurement results obtained. The multi-way speakers 11, 20, and 2 and the super woofers 14, 24, and 4 shown in FIGS.
Are constituted by the same main permanent magnet, and the canceling permanent magnets 22 and 6 and 26 and 7 are the same. For comparison, a conventional loudspeaker system without reverse magnetization in the configuration of FIG. 1 was also measured. The number of speaker units measured in each of the above configurations is ten. The results are shown below. The configuration without reverse magnetization is Comparative Example 1, the configuration in FIG. 3 employing the cancel magnet method in the configuration of Conventional Example 1 is Comparative Example 2, and the configuration in FIG. 2 will be described as a second embodiment. The distances between the frames of Comparative Examples 1 and 2 are all 1 cm. In Comparative Example 1, there is a variation of 10.51 Gauss to 7.79 Gauss near the multiway speaker, and the average value is about 9.10 Gauss, and 12.23 Gauss to 9.54 near the super woofer. Gaussian variation and average value is about 10.60 Gauss,
The leakage magnetic flux as a speaker system is 10.60 gauss. In Comparative Example 2, there is a variation of 3.70 gauss to 2.74 gauss near the multiway speaker, and the average value is about 3.20 gauss, and a variation of 6.35 gauss to 4.82 gauss near the super woofer. The average value is 5.50 gauss, and the leakage magnetic flux as a speaker system is 5.50 gauss. The average effect of the cancel magnet method of Comparative Example 2 is that the demagnetization is about 35% near the multiway speaker and about 52% near the super woofer, but the demagnetization effect of the speaker system is 52%. It is. On the other hand, in the first embodiment, there is a variation of 7.67 gauss to 5.80 gauss near the multiway speaker, and the average value is 6.86 gauss, and 7.98 gauss to 5.78 gauss near the super woofer. The average value is about 7.16 Gauss, and the leakage magnetic flux as the speaker system is 7.16 Gauss. Comparing Example 1 and Comparative Example 1 with average values, the demagnetizing effect is about 75% near the multiway speaker and about 67% near the super woofer, and the demagnetizing effect as a speaker system is 67%. . Comparing Example 1 with Comparative Example 2, Example 1 is slightly inferior in the demagnetizing effect. For example, when a television is arranged in close contact between a pair of speakers and a television image is viewed, 10 Gauss or more is obtained. In this case, almost everyone can visually recognize that there is more in the video, and the disturbance of the video signal is so severe that the visibility is significantly impaired. Since it is not enough to hinder the visual recognition, there is no factor in increasing the cost of providing the cancel permanent magnet, and therefore, it is of great practical value. In the second embodiment, there is a variation of 3.20 Gauss to 2.37 Gauss near the multiway speaker, and the average value is 2.80 Gauss, and the mean value is 6.05 Gauss to 4.64 Gauss near the super woofer. The average value is about 5.30 Gauss, and the leakage magnetic flux as the speaker system is 5.30 Gauss. Comparing Example 2 and Comparative Example 1 with an average value, the demagnetizing effect is about 31% near the multiway speaker and about 50% near the super woofer, and the demagnetizing effect as the speaker system is 50%. . Comparing Example 2 with Comparative Example 2, the demagnetizing effect is about 88% near the multiway speaker and about 96% near the super woofer, but not as much as the demagnetizing effect from Comparative Example 1. In view of the cost required for the conventional demagnetization countermeasures using the canceled permanent magnet, the demagnetizing effect can be exhibited in spite of a very simple configuration in which only one of the main permanent magnets is reversely magnetized. Since the reverse magnetization method of the present invention also depends on the separation distance between the speakers adjacent to each other, the first embodiment described above is used.
However, the effect of the present invention cannot be discussed by itself, but if the distance d between the frames 17 and 18 shown in FIG.
The demagnetizing effect on the configuration of
cm or less is preferred. In the above description, a speaker system having two speakers, that is, a multi-way speaker and a super woofer, has been described. ) The magnetization direction of the main permanent magnet is
Needless to say, the present invention can be applied even if the two magnetization directions are different. As described above, according to the present invention, a predetermined demagnetization effect can be obtained without using a cancel permanent magnet, so that the leakage magnetic flux can be reduced while suppressing the price increase of the speaker system. There is also an effect that can be performed.

[Brief description of the drawings] FIG. 1 is an explanatory diagram of the configuration of an embodiment of the present invention. FIG. 2 is an explanatory diagram of a configuration of another embodiment of the present invention. FIG. 3 is an explanatory diagram of a conventional configuration. [Explanation of symbols] 10, 19 Speaker system 11, 20 Multi-way speaker 14, 24 Super woofer speaker 12, 15, 21, 25 Main permanent magnet 13, 16, 23, 27 Magnetic field direction

Claims (1)

Claims 1. A speaker system in which the vibration centers of a plurality of speakers are arranged substantially on a straight line, wherein the speakers generate a magnetic field for a voice coil connected to the diaphragm. A pair of the main permanent magnets of the speakers adjacent to each other, the directions of the lines of magnetic force generated by the pair of main permanent magnets are magnetized in opposite directions on the side of the pair of main permanent magnets facing the side of the magnetic pole direction. Leakage flux reduction method.