JP2005354836A - Magnetizer, voice call motor, and method of manufacturing voice call motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique which enables magnetization where the respective neutral positions of counterposed magnets conform to each other. <P>SOLUTION: A magnetizer is equipped with an upper head 21 and a lower head 22 which are used in close contact with an upper yoke 11 and a lower yoke 12, respectively, and a middle head 23 which is used, being inserted in the air gap 17 between counterposed permanent magnets. The above magnetizing coils 21, 22, and 23 are arranged on a cover where constructional elements other than coils constituting a magnetic circuit are assembled, and specified intensity of pulse currents are let flow at the same time to these three magnetizing heads 21, 22, and 23 so as to magnetize the permanent magnet 13 provided at the upper yoke 11 and the permanent magnet 14 provided at the lower yoke 12 at the same time in a one-time process. Since the position within a magnetic circuit of the permanent magnet is decided before magnetization, it becomes possible to magnetize them, aligning the respective neutral zone positions of the counterposed magnets with each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a voice coil motor manufacturing technique, and more particularly to an apparatus for magnetizing a permanent magnet provided in a voice coil motor and a method of manufacturing a voice coil motor.

  A linear motor is a motor that converts electric energy into mechanical energy using magnetic flux generated by a magnet, and is widely used as a means for giving a linear motion to an object to be driven. For example, a hard disk device (hereinafter referred to as “HDD”) is one of storage devices for computers, and a linear motor is also used for the HDD.

  The HDD includes a hard disk that is a recording medium, a magnetic head unit that records and reads information on the hard disk, and a magnetic head drive unit that is an actuator that drives the magnetic head unit. The magnetic head drive unit is a motor for positioning the magnetic head on the hard disk, and is called a voice coil type linear motor (hereinafter simply referred to as “voice coil motor (VCM)”) which is a kind of linear motor. Is provided). The VCM in the HDD is used to position the magnetic head at a desired position in the radial direction of the hard disk at high speed and accurately, and is driven by applying a magnetic force to the voice coil in order to reduce the size of the VCM. In general, rare earth magnets (samarium / cobalt magnets, neodymium / iron / boron magnets, etc.) having large magnetic energy are used as permanent magnets.

  FIG. 1 is a diagram for explaining an example of the structure of a VCM used in an HDD. In the figure, reference numeral 11 denotes an upper yoke, reference numeral 12 denotes a lower yoke, reference numeral 13 denotes a permanent magnet provided on the upper yoke 11, and reference numeral 14 Is a permanent magnet provided in the lower yoke 12, reference numerals 15 and 16 are spacers forming a gap 17 between the permanent magnet 13 provided in the upper yoke 11 and the permanent magnet 14 provided in the lower yoke 12, and Reference numeral 18 denotes a drive coil (actuator) inserted in the gap 17 (see Patent Document 1 and Patent Document 2 for details of the configuration). The upper yoke 11 and the lower yoke 12 are made of a magnetic material, and the magnetic circuit of the VCM is composed of the upper yoke 11, the lower yoke 12, and the gap 17, and the permanent magnets 13 and 14 are in the magnetic field direction of the magnetic circuit. To decide. The driving coil 18 can move in a horizontal plane under the action of electromagnetic force generated by the magnetic field formed in the gap 17. For example, the magnetic head can be positioned at high speed and accurately at a desired position in the radial direction of the hard disk. To do.

  A conventional process for manufacturing such a VCM is as follows. First, a plate-like permanent magnet 13 is fixed on one surface of the upper yoke 11, and a plate-like permanent magnet 14 is fixed on one surface of the lower yoke 12 with an adhesive or the like. Next, the permanent magnet 13 fixed to the upper yoke 11 and the permanent magnet 14 fixed to the lower yoke 12 are magnetized separately. Alternatively, the permanent magnets 13 and 14 may be magnetized alone and adhered to the upper yoke 11 and the lower yoke 12. A gap 17 is provided between the upper yoke 11 and the lower yoke 12 so that the magnetized permanent magnet 13 and the permanent magnet 14 face each other, and a space 17 is further provided. Assembly is completed by inserting the coil 18 for use. The spacers 15 and 16 may be integrated with the upper yoke 11 and / or the lower yoke 12.

Thus, when manufacturing a voice coil motor having a magnetic circuit having magnets provided to face each other, first, the individual magnets are individually magnetized, and then assembled, The “post-magnetization assembly method” is used.
Japanese Patent Laid-Open No. 2004-23969 JP-A-6-251517

  However, the “post-magnetization assembly method” described above has the following problems. First, it is virtually impossible to precisely match the “neutral zone position” of each of these magnets placed one above the other for assembly after the magnets have been magnetized. For this reason, a decrease in torque linearity and occurrence of vibrations due to a shift in the neutral zone position of the upper and lower magnets occurs. Secondly, since magnetizing is to align the magnetization direction of the permanent magnet, when assembling the magnetized member, the assembly work must be performed under the action of strong magnetic force from the magnet with the aligned magnetization direction. The work efficiency must be reduced. In addition, under such a strong magnetic force, it is difficult to avoid “rubbing” between members that are combined with each other, and the surface of the member may be damaged or particles may be generated from a part of the member. Cause a nation.

  The present invention has been made in view of such a problem, and an object of the present invention is to enable a “post-assembly magnetization method” in which magnetization is performed after the constituent members of the voice coil motor are assembled. A magnetizing device and a method of manufacturing a voice coil motor using the magnetizing device are provided.

  In order to solve such a problem, the present invention provides a first and second pair of plates which are provided to face each other so as to have a gap between the main surfaces of the plate magnet. A magnetizing device for magnetizing a magnet, wherein a first magnetizing head disposed on the back side of the first plate magnet and a first magnet disposed on the back side of the second plate magnet The magnetizing current is supplied to the respective coils of the second magnetizing head, the third magnetizing head inserted in the gap, and the first, second, and third magnetizing heads. And a power supply unit.

  According to a second aspect of the present invention, in the magnetizing device according to the first aspect, the coil provided in the third magnetic head is a one-turn coil or a plurality of turn coils, and extends from one end of the coil. The first current path is divided into the second and third current paths at the tip of the coil, and the respective ends of the two current paths are combined as the other end of the coil, The distal end portion of the coil has an E-shape in which the second current path and the third current path are arranged so as to extend across the first current path.

  According to a third aspect of the present invention, there is provided the magnetizing device according to the first or second aspect, wherein a tip portion of the coil is provided between the second current path and the first current path, and the first current path. The magnetic flux converging means made of a magnetic material is provided between the three current paths and the first current path.

  According to a fourth aspect of the present invention, in the magnetizing apparatus according to any one of the first to third aspects, the third magnetizing head is provided with driving means for positioning in the three axial directions within the gap. It is characterized by that.

  The invention according to claim 5 is a voice coil motor, comprising at least one pair of plate magnets magnetized by the magnetizing device according to any one of claims 1 to 4. To do.

  The invention according to claim 6 is a method of manufacturing a voice coil motor, the first step of fixing an unmagnetized plate-shaped magnet to one main surface of each of the first yoke and the second yoke; A second step of assembling a lid having a gap between the plate magnets by fixing a pair of the plate magnets fixed to each other and fixing a spacer to the first and second yokes; A first magnetizing head is disposed on the other main surface side of one yoke, a second magnetizing head is disposed on the other main surface side of the second yoke, and a third magnetizing head is disposed in the gap. And a fourth step of simultaneously magnetizing the pair of plate magnets by supplying a magnetizing current to each coil of the first, second, and third magnetizing heads. And.

  By using the magnetizing apparatus of the present invention, magnetizing can be performed after the constituent members of the voice coil motor are assembled, so that the neutral zone positions of the opposing magnets can be matched. In addition, torque linearity can be improved and vibration can be suppressed. In addition, it is possible to improve the work efficiency because the assembly work can be performed in a state where it is released from the magnetic force action from the magnet whose magnetization direction is aligned by magnetization, resulting in friction between members. The generation of scratches on the surface of the member and the generation of particles from the member are also suppressed. In addition, in the conventional “post-magnetization assembly method”, the magnetizing process required for the number of times corresponding to the number of permanent magnets included in the voice coil motor is only one, and the assembling process can be simplified. . Furthermore, since a plurality of permanent magnets can be magnetized at the same time, the VCM assembly jig can be simplified and the manufacturing cost can be reduced.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the following embodiments, the voice coil motor to be magnetized will be described as the voice coil motor (VCM) having the configuration shown in FIG. 1, but the magnetization using the magnetizing apparatus of the present invention will be described below. The present invention is not limited to the VCM of this configuration, and any VCM having a structure using a magnetic circuit in which a permanent magnet is provided in a gap formed by a yoke can be applied to the magnetization. Is clear.

  The magnetizing apparatus of the present invention includes at least three magnetizing heads. Two of these magnetizing heads are an upper head and a lower head that are used in close contact with the upper yoke 11 and the lower yoke 12, and in addition to these magnetizing heads, a magnet formed by laminating a permanent magnet and a yoke. An intermediate head is provided which is incorporated into a circuit and used by being inserted into a gap (gap) of permanent magnets provided to face each other. The number of medium heads can be appropriately changed according to the number of laminated permanent magnets of the voice coil motor (the number of air gaps between the permanent magnets). However, when the number of air gaps is 1 as in the VCM shown in FIG. Is also one. Then, a permanent magnet 13 provided in the upper yoke 11 and a permanent magnet provided in the lower yoke 12 by causing a pulse current of a predetermined intensity to flow simultaneously through these three magnetized heads (upper head, middle head, and lower head). 14 are simultaneously magnetized in one step.

  FIG. 2 is a conceptual diagram for explaining a configuration example of the magnetizing apparatus of the present invention. This magnetizing apparatus includes three magnetizing heads (upper head 21, middle head 23, and lower head 22) for magnetizing a permanent magnet included in an unmagnetized VCM assembly, and these The head coil 24 provided at the tip of the middle head 23 and the head coil 24 provided at the tip thereof are positioned in three orthogonal (XYZ) directions within the gap 17 of the VCM assembly, and a magnetized power supply unit 26 is provided.

  The magnetized power supply unit 26 is a device for applying a magnetizing current to the coils of the upper, middle, and lower magnetized heads 21, 22, and 23. The magnetized power source unit 26 includes an upper head, a middle head, A magnetizing power source 27 that is a power source for each of the lower head and the lower head is provided, and the permanent magnets 13 and 14 are magnetized by a magnetizing current supplied from the magnetizing power source 27 to each head. The upper head 21 and the lower head 22 are sized so as to cover the entire permanent magnets 13 and 14 to be magnetized. Further, the thickness of the head coil 24 provided at the tip of the middle head 23 is set to be equal to or less than the gap 17 between the upper and lower permanent magnets.

  The magnitude of the current supplied from the magnetizing power source 27 to the upper, middle, and lower magnetizing heads 21, 22, and 23 can be independently set by a current control unit 28 provided in the magnetizing power source unit 26. The stage 25 is used for positioning the upper head 21, the lower head 22, and the middle head 23, and for adjusting the position of the head coil 24 in the gap 17, and is a triaxial that can finely adjust each position in the X, Y, and Z directions. The table is driven and controlled by, for example, a controller 29 provided in the magnetized power supply unit 26.

  FIG. 3 is a diagram for explaining the mutual positional relationship of the three magnetizing heads provided in the magnetizing apparatus of the present invention. The middle head is inserted into the gap provided in the yoke sandwiched between the upper head and the lower head. The upper head 21, the lower head 22, and the middle head 23 are arranged so that a permanent magnet (not shown) is magnetized to form a magnetic flux in a desired direction in the magnetic circuit. These heads are positioned relative to each other so that their coil centerlines (A, B, and C in the figure) coincide with each other, and the positioning is performed by using positioning pins (not shown). The upper head 21 and the lower head 22 are two-pole magnetized heads having a pair of N and S poles, and are symmetrical so that the magnetization directions of the upper and lower permanent magnets 13 and 14 are the same. Be placed. The middle head 23 is also a two-pole magnetized head having a pair of N and S poles. The head coil 24 of the middle head 23 completely covers the vicinity of the neutral zone of the magnet in the gap 17, and the upper head 21 and the lower head. It arrange | positions in the center part of the space | gap 17 part between upper and lower heads so that the magnetic flux of the same direction as the direction of the magnetic flux generated from the head 22 may generate | occur | produce.

  Each head is provided with magnetizing current supply terminals 21a, 21b, 22a, 22b, 23a, and 23b. A magnetizing current is supplied from these terminals to simultaneously energize the coils of each head. By this energization, a magnetic flux is generated in the coil of each magnetizing head, the permanent magnet is magnetized, and a magnetic circuit in which the neutral zone positions of the upper and lower permanent magnets coincide is obtained. There are no particular restrictions on the material of the permanent magnet and the yoke constituting the magnetic circuit of the VCM magnetized by such a magnetizing head, but the permanent magnets to be magnetized include, for example, rare earth magnets, ferrite magnets, alnicos. Low carbon steel (especially cold rolled steel), silicon steel, etc. are used for the magnetic material used for the yoke, such as a magnet.

  FIG. 4 is a diagram for explaining the shape of the magnetized coil of the middle head. The head coil 24 (the part that is actually magnetized) provided in the middle head 23 is a one-turn coil whose tip 24a is E-shaped. It is. The tip 24a does not need to be large enough to cover the entire surface of the permanent magnet to be magnetized, but only needs to be large enough to magnetize the vicinity of the neutral zone of the permanent magnet. Alternatively, it is preferable to cover a region of 10 to 50% near the neutral. The E-shaped one-turn coil is magnetized by magnetic fluxes B1 and B2 formed by flowing a magnetizing current in the direction indicated by an arrow in the figure through terminals 23a and 23b. The lead portions 24b and 24c at both ends of the head coil 24 are not limited in shape as long as they have a structure capable of supplying a magnetizing current input from the terminals 23a and 23b to the coil. If desired, magnetic materials 24d and 24e such as pure iron are provided inside the E-shaped portion of the coil tip 24a to efficiently converge the magnetic flux generated around the E-shaped portion of the coil tip 24a. You may do it. As shown in the schematic plan view of FIG. 4 (b) and the schematic sectional view of FIG. 4 (c), the coil tip 24a is inserted into the gap 17 of the assembled VCM lid 10 and is magnetized. Is energized.

  In the magnetizing apparatus shown in the present embodiment, the permanent magnet to be magnetized is configured as a head that magnetizes the N pole and the S pole so that each of the N pole and the S pole is one pole. However, the present invention is not limited to this, and a configuration in which only one pole is magnetized or a configuration in which three or more poles are magnetized can be employed. In that case, the number of coils provided in each magnetizing head is the same as the number corresponding to the number of magnetic poles, and the magnetizing power supply for supplying the magnetizing current to the coils of each magnetizing head is provided. Be prepared for. Further, as described above, a plurality of the medium heads may be provided according to the number of stages of the permanent magnets to be stacked.

  Below, the manufacturing process of VCM manufactured using the magnetizing apparatus of this invention is demonstrated.

  FIG. 5 is a flowchart for explaining a manufacturing process of the VCM having the structure shown in FIG. 1 manufactured in this embodiment. First, the upper yoke 11 and the lower yoke 12 are obtained by a technique such as an integral molding method (step S101). The material of these upper yoke 11 and lower yoke 12 is a low carbon steel magnetic material, and is obtained by processing a plate material cut into a predetermined size. In addition, the surface of these yokes is plated or painted with nickel or the like to be rust-proofed. Further, the permanent magnets 13 and 14 are formed by a powder sintering method or the like (step S102). In general, the surface of these permanent magnets is subjected to a surface treatment such as Ni plating.

  Next, the plate-like permanent magnet 13 is fixed to a predetermined position of the upper yoke 11 with an adhesive or the like, and similarly the plate-shaped permanent magnet 14 is fixed to a predetermined position of the lower yoke 12 with an adhesive or the like (step S103). . In the VCM, in order to use an effective magnetic field generated in the gap 17 formed in a partial region of the magnetic circuit, the permanent magnets 13 and 14 having high magnetic energy per unit area are required. For this reason, a material having excellent hysteresis characteristics is selected as the material of the permanent magnets 13 and 14. Here, an Nd—Fe—B based sintered magnet is used as the permanent magnet.

  After the permanent magnet is fixed to the yoke, a pair of spacers 15 and 16 are fixed to a predetermined position of the lower yoke 12 to which the permanent magnet 14 is fixed with an adhesive or the like, and the spacers 15 and 16 are fixed to the upper portion where the permanent magnet 13 is fixed. The yoke 11 is fixed to a predetermined position with an adhesive or the like (step S104). Thereby, a gap 17 constituting a magnetic circuit is provided between the permanent magnet 13 and the permanent magnet 14. In a state where the above-described components are assembled, the permanent magnet 13 and the permanent magnet 14 are magnetized using the magnetizing apparatus of the present invention shown in FIG. A multipolar magnetized magnet is formed in the magnetizing process (step S105).

  FIG. 6 is a conceptual diagram for explaining the magnetization state in step S105. The upper head 21 and the lower head 22 of the magnetizing apparatus sandwich the upper yoke 11 and the lower yoke 12 of the VCM (lid body) 10 before the voice coil is inserted, and the head coil 24 of the middle head is inserted into the gap 17. . Then, the permanent magnets 13 and 14 are magnetized by applying a pulse current of 8 to 30 kA to the coils 21c, 22c and 24 of all the heads at the same time to generate a magnetic flux. When magnetization is performed in such a process, the position of the permanent magnet in the magnetic circuit is determined before magnetization, so that it is possible to match the neutral zone positions of the opposing magnets. Become. Finally, a driving coil is inserted into the gap 17 to obtain the VCM shown in FIG. 1 (step S106).

In this embodiment, each component member is fixed with an adhesive or the like. However, in order to avoid contamination due to gas outflow from the adhesive or a decrease in adhesive strength, the respective component members are mutually locked. It is good also as fixing without relying on an adhesive as providing the unevenness | corrugation shaped so.
(Comparative Example 1)

  The positions and widths of the neutral zones of the multipolar magnetized magnets respectively provided in the VCM produced by the “post-assembly magnetization method” of the present invention and the VCM produced by the conventional “post-magnetization assembly method” are shown below. The comparison result will be described. The position and width of the neutral zone of the multipolar magnetized magnet of the VCM produced by the “post-assembly magnetizing method” were measured by disassembling the magnetized VCM and taking out the upper yoke and the lower yoke. On the other hand, the position and width of the neutral zone of the VCM multipole magnet produced by the “post-magnetization assembly method” are measured after magnetizing each of the magnets provided in the upper and lower yokes. Yes. Specifically, a magnet viewer generally used for observing the magnetized state of the magnet is brought into close contact with the magnetic surface of each of the magnets magnetized with multiple poles, and the color of the magnet viewer is changed (no color change). ) The area is measured and evaluated with a two-dimensional measuring instrument.

  In this comparative example, both the “post-assembly magnetization method” VCM and the “post-magnetization assembly method” VCM are made of low-carbon steel, and the multipolar magnet is Nd—Fe—B. It is a system sintered magnet. Further, when magnetizing a multi-pole magnet by the post-assembly magnetizing method, the magnet is magnetized by simultaneously applying a current of 8 to 30 kA to all the coils of the magnetizing apparatus described in FIG.

  FIG. 7 is a diagram for explaining how the position and width of the neutral zone are evaluated by the magnet viewer. When the magnet viewer 70 is brought into close contact with the magnetic surface of the multipolar magnetized magnet (two poles in this case), Corresponding portions (magnetized portions) are discolored 71 and 72 in black, and discoloration does not occur in portions that are not magnetized. Accordingly, the position and width of the magnetically neutral neutral zone 73 between the two magnetized regions can be measured.

  Table 1 shows the neutral zone width (mm) of the multipolar magnetized magnets that are evaluated by the “post-assembly magnetization method” VCM and the “post-magnetization assembly method” VCM, which are evaluated by such a method. It is a compilation of data. In order to obtain data reliability, three types of multi-pole magnetized magnets for VCM, A, B, and C, are prepared for each type.

この表に示した結果から明らかなように、上部ヨークと下部ヨークの何れに設けられた多極着磁磁石においても、ニュートラルゾーン幅は組立後着磁方式のＶＣＭにおいて狭く、かつＶＣＭ間でのニュートラルゾーン幅のばらつきも小さくなっている。

As is apparent from the results shown in this table, the neutral zone width is narrow in the post-assembly magnetized VCM and the VCM between the VCMs in any of the multipolar magnets provided in the upper yoke and the lower yoke. The variation in the neutral zone width is also reduced.

  Table 2 summarizes the results of measuring the deviation (mm) of the neutral zone position of the multipole magnetized magnets provided on the upper and lower yokes of the “post-assembly magnetized” VCM of the present invention. is there. In order to obtain data reliability, four VCMs (D, E, F, and G) prepared by the post-assembly magnetization method are prepared and evaluated.

この表に示すように、ニュートラルゾーン位置のずれ量の平均値は０．０３５ｍｍであり、最大でも０．０４０ｍｍとなっている。一般的なＶＣＭのニュートラルゾーンの位置ずれ規格（許容量）は０．２ｍｍ以下とされていることからすると、組立後着磁方式で作製された本発明のＶＣＭは上記規格を再現性よく且つ充分に満足している。また、従来の着磁後組立方式で作製されたＶＣＭのニュートラルゾーンの位置ずれ量は概ね０．２〜０．３ｍｍ程度であることを考慮すると、本発明の組立後着磁方式で作製されたＶＣＭでは、ニュートラルゾーンの位置ずれ量が大幅に低減されていることが分かる。すなわち、磁石を着磁させた後で組立を行う従来の着磁後組立方式では、上下に配置される多極着磁磁石の各々の「ニュートラルゾーン位置」を正確に一致させることが困難であるのに対して、本発明の組立後着磁方式では上下の磁石の各々のニュートラルゾーン位置の一致度を大幅に改善することが可能となる。
（比較例２）

As shown in this table, the average value of the shift amount of the neutral zone position is 0.035 mm, and is 0.040 mm at the maximum. Since the position deviation standard (allowable amount) of the neutral zone of a general VCM is set to 0.2 mm or less, the VCM of the present invention manufactured by the post-assembly magnetization method is sufficiently reproducible and sufficient. We are satisfied with. In addition, considering that the positional shift amount of the neutral zone of the VCM manufactured by the conventional post-magnetization assembly method is about 0.2 to 0.3 mm, it was manufactured by the post-assembly magnetization method of the present invention. It can be seen that in the VCM, the amount of displacement in the neutral zone is greatly reduced. That is, in the conventional post-magnetization assembling method that assembles after magnetizing the magnets, it is difficult to accurately match the “neutral zone positions” of the multipolar magnets arranged above and below. On the other hand, in the post-assembly magnetization method of the present invention, the degree of coincidence between the neutral zone positions of the upper and lower magnets can be greatly improved.
(Comparative Example 2)

  Hereinafter, the results of comparing the torque linearity of the VCM produced by the “post-assembly magnetization method” of the present invention and the VCM produced by the conventional “post-magnetization assembly method” will be described. In this comparative example, both the “post-assembly magnetization method” VCM and the “post-magnetization assembly method” VCM are made of low-carbon steel, and the multipolar magnet is Nd—Fe—B. It is a system sintered magnet. Further, when magnetizing a multi-pole magnet by the post-assembly magnetizing method, the magnet is magnetized by simultaneously applying a current of 8 to 30 kA to all the coils of the magnetizing apparatus described in FIG.

  Table 3 summarizes the results of obtaining the torque linearity from the maximum value and the minimum value of the torque coefficient (thrust constant) Kt of the VCM of the “post-assembly magnetization method” and the VCM of the “post-magnetization assembly method”. . Here, the torque linearity is an index of the linearity of the driving torque, and is an index that the torque does not change within the driving range. The higher this value, the greater the possibility of a disk write error and the slower the seek speed. The torque coefficient Kt is a proportional coefficient (F = Kt · i) with the force F generated in the VCM when the current flowing through the voice coil is i, and its unit is mN · m / A. In addition, in order to obtain the average torque linearity of the VCM of each method, two VCMs, H and I, and H ′ and I ′, were produced and evaluated for each method.

この表に示した結果によれば、「組立後着磁方式」のＶＣＭのトルクリニアリティは、「着磁後組立方式」のＶＣＭのトルクリニアリティに比較して１％程度改善されている。これは、構成部材を組み立てた状態で磁石の着磁を行う「組立後着磁方式」により組み立てられたＶＣＭにおいては上下に対向して設けられた磁石の各々のニュートラルゾーン位置が一致することによる特性改善効果である。

According to the results shown in this table, the torque linearity of the “post-assembly magnetization method” VCM is improved by about 1% compared to the torque linearity of the “post-magnetization assembly method” VCM. This is because in the VCM assembled by the “post-assembly magnetization method” in which the magnets are magnetized in the state in which the constituent members are assembled, the neutral zone positions of the magnets provided facing each other in the vertical direction coincide. This is a characteristic improvement effect.

  FIG. 8 is a diagram for explaining the result of measuring the magnetic field distribution Bg between the multipolar magnetized magnets of the VCM produced by the above two methods. No significant difference is observed in the inter-magnet magnetic field distribution Bg with the “post-magnetic assembly method” VCM.

  The magnetizing device of the present invention is a magnetizing device for enabling the “post-assembly magnetizing method” in which magnetizing is performed after the constituent members of the voice coil motor are assembled. By using this magnetizing device, It is possible to magnetize the respective neutral zones of the magnets provided facing each other so that the torque linearity can be improved and the occurrence of vibration can be suppressed.

It is a figure for demonstrating the structural example of VCM used for HDD. It is a conceptual diagram for demonstrating the structural example of the magnetizing apparatus of this invention. It is a figure for demonstrating the mutual positional relationship of the three magnetizing heads with which the magnetizing apparatus of this invention is provided. It is a figure for demonstrating the shape of the magnetizing coil of a middle head. It is a flowchart for demonstrating the manufacturing process of VCM of this invention. It is a conceptual diagram for demonstrating the mode of magnetization. It is a figure for demonstrating a mode that the position and width | variety of a neutral zone are evaluated by a magnet viewer. It is a figure explaining the result of having measured the magnetic field distribution Bg between the multi-pole magnetized magnet of the post-assembly magnetization type VCM and the post-magnetization assembly type VCM.

Explanation of symbols

11 Upper yoke 12 Lower yoke 13 Upper permanent magnet 14 Lower permanent magnets 15 and 16 Spacer 17 Air gap 18 Driving coil (actuator)
21 Upper head 22 Lower head 23 Middle head 21a, 21b, 22a, 22b, 23a, 23b Magnetization current supply terminal 24 Head coil 25 Stage 26 Magnetization power supply unit 27 Magnetization power supply 28 Current control unit 29 Controller

Claims (6)

A magnetizing device that magnetizes a first and second pair of plate magnets provided facing each other so as to have a gap between the main surfaces of the plate magnets,
A first magnetizing head disposed on the back surface side of the first plate magnet, a second magnetizing head disposed on the back surface side of the second plate magnet, and being inserted into the gap. And a power supply unit that supplies a magnetizing current to the coils of the first, second, and third magnetizing heads. Magnetic device. The coil included in the third magnetizing head is a one-turn coil or a multi-turn coil, and the first current path extending from one end of the coil is the second and third two at the tip of the coil. The current paths are separated, and the ends of the two current paths are combined as the other end of the coil,
The tip portion of the coil has an E-shape in which the second current path and the third current path are arranged so as to extend across the first current path. Item 2. The magnetizing device according to item 1. The tip of the coil is made of a magnetic material between the second current path and the first current path and between the third current path and the first current path. 3. A magnetizing apparatus according to claim 1, further comprising a magnetic flux converging means. 4. A magnetizing apparatus according to claim 1, further comprising driving means for positioning the third magnetizing head in three axial directions within the gap. A voice coil motor comprising at least one pair of plate magnets magnetized by the magnetizing device according to claim 1. A first step of fixing an unmagnetized plate magnet to one main surface of each of the first yoke and the second yoke;
A second step of assembling a lid having a gap between the plate magnets by fixing the pair of fixed plate magnets to each other, fixing a spacer to the first and second yokes, and
A first magnetizing head is disposed on the other main surface side of the first yoke, a second magnetizing head is disposed on the other main surface side of the second yoke, and a third magnetizing head is disposed in the gap. A third step of arranging the magnetic head;
And a fourth step of simultaneously magnetizing the pair of plate magnets by supplying a magnetizing current to each coil of the first, second and third magnetizing heads. A method for manufacturing a voice coil motor.

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