JP4517469B2 - Magnetization position detection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for detecting a magnetization position, and more particularly to a method for detecting a magnetization position of a magnet used in a hard disk drive.
[0002]
[Prior art]
Conventionally, a voice coil motor used for a head position adjusting mechanism of a hard disk drive (hereinafter referred to as an HDD) is known. In this voice coil motor, magnets magnetized on a plurality of poles are arranged opposite to each other, and coils are arranged between the opposed magnets. Thereby, the coil is swung to a predetermined position by generating a repulsive force between the magnetic field space formed by the magnets arranged opposite to each other and the magnetic field generated by the coil. Thereby, the position control of the head position is performed.
[0003]
In such a voice coil motor, if the magnetized position of the magnet for forming the magnetic field space is slightly deviated, it becomes difficult to control the head of the HDD device to a desired position. In particular, since the track width of the disk has recently been reduced, such inconvenience is becoming more pronounced.
[0004]
Conventionally, in consideration of the above disadvantages, the magnetized state is inspected by detecting the magnetized position after magnetizing the magnet. 3 and 4 are schematic diagrams for explaining a conventional method of detecting a magnetized position.
[0005]
First, with reference to FIGS. 3 and 4, a detection apparatus used in a conventional method for detecting a magnetization position will be described. In a conventional magnetizing position detection device, a reference block (datum) 102 serving as a position reference for the magnet 151 is provided on the mounting table 101. A plurality of projections 103 for positioning the base plate 150 provided integrally with the magnet 151 with respect to the datum 102 are provided on the mounting table 101.
[0006]
A magnetic sheet 105 for detecting the magnetized state of the magnet 151 is provided. In the magnetic sheet 105, a magnetic material is movably held, and the magnetic material moves according to the magnetized state of the magnet 151. Therefore, the magnetized state of the magnet 151 can be determined from the movement state (distribution state) of the magnetic body. Further, as shown in FIG. 4, the mounting table 101 is configured to be movable in the XY direction and the rotation direction. A meter 106 for detecting the movement distance in the X direction is provided as shown in FIG.
[0007]
Next, a method for detecting the magnetization position using the conventional detection device having the above-described configuration will be described.
[0008]
First, as shown in FIG. 3, a base plate 150 to which a magnetized arcuate magnet 151 is attached is attached to a plurality of protrusions 103 provided on the mounting table 101. Then, the magnetic sheet 105 is disposed on the upper surface of the magnet 151.
[0009]
In this state, the magnetic sheet 105 and the datum 102 are photographed from above by a camera (not shown), and a photographed image is displayed on a television screen (not shown). Then, by moving the mounting table 101 in the XY direction and the rotation direction, the XY axes of the datum 102 on the mounting table 101 are aligned with the XY axes that are the reference on the screen. This state is the state shown in FIG. In this state, the Y axis on the screen coincides with the center position (neutral center) of the position where the magnet 151 is to be magnetized. That is, the center position of the position to be magnetized is detected by the alignment operation of the XY axes.
[0010]
Next, from the state shown in FIG. 4, the mounting table 101 is moved in the X direction so that the Y-axis on the screen is at the position of the N pole side end 151 a of the magnet 151. The position of the N pole side end 151a of the magnet 151 is visually identified by the operator from the distribution of the magnetic material of the magnetic sheet 105 projected on the screen. In this case, the amount of movement of the mounting table 101 in the X direction is the distance from the center position (neutral center) of the magnet 151 to the N pole side end portion 151a. Further, from the state shown in FIG. 4, the mounting table 101 is moved in the X direction so that the Y axis on the screen is positioned at the S pole side end 151b. As a result, the amount of movement in the X direction is the distance from the center position (neutral center) of the magnet 151 to the S pole end 151b. Note that the amount of movement of the mounting table 101 in the X direction is measured by the meter 106.
[0011]
The amount of deviation is calculated by comparing the measured distances from the center position of the magnet 151 to the N pole side end portion 151a and the S pole side end portion 151b with design values. Then, the non-defective product and the defective product are identified by determining whether or not the deviation amount exceeds the allowable value.
[0012]
[Problems to be solved by the invention]
In the above-described conventional method for detecting the magnetized position, the work for aligning the XY axis on the screen and the XY axis of the datum 102, and the subsequent magnet center position (neutral center), the N pole end 151a. And the operation | work which measures the distance to S pole side edge part 151b was performed by the operator moving the mounting base 101 manually. For this reason, there has been a problem that it takes a long time to detect the magnetization position. As a result, conventionally, it has been difficult to shorten the time for detecting the magnetization position.
[0013]
Conventionally, the above-described alignment operation of the XY axes (operation for detecting the center position of the position to be magnetized) and the operation for measuring the distance from the center position to the magnetization position (the actual magnetization position is determined). Since the measurement operation is performed by visual observation by the operator, there is a problem that the alignment accuracy and measurement accuracy are low. For this reason, it is difficult to improve the detection accuracy of the magnetized position.
[0014]
For the reasons described above, conventionally, it has been difficult to detect the displacement of the magnetized position quickly and with high accuracy.
[0015]
The present invention has been made to solve the above problems,
One object of the present invention is to provide a method for detecting a magnetized position capable of detecting a displacement of the magnetized position quickly and with high accuracy.
[0016]
Another object of the present invention is to provide a method for detecting a magnetized position that can shorten the time for detecting the magnetized position and improve the accuracy of detecting the magnetized position. .
[0017]
[Means for Solving the Problems]
The method for detecting a magnetized position according to claim 1 includes a step of calculating a position where a magnet should be magnetized based on image information relating to a magnet to be inspected, and a magnetic sheet on which a magnetic body is movably held. And a step of detecting an actual magnetization position of the magnet based on image information obtained by photographing the magnetic sheet, and a calculated position to be magnetized and a detected actual magnetization position. And a step of comparing. Here, the image information regarding the magnet is a wide concept including not only image information of the shape of the magnet itself but also image information of a portion (datum) serving as a reference for the position of the magnet.
[0018]
In the first aspect of the present invention, as described above, by automatically calculating the position where the magnet should be magnetized based on the image information regarding the magnet, the reference position of the magnet and the reference position on the screen as in the conventional case are used. There is no need for an operator to manually move the mounting table and perform alignment by visual observation in order to perform alignment (operation for detecting a position to be magnetized). Thereby, the detection operation of the position to be magnetized can be performed in a short time and with high accuracy. Further, by automatically detecting the actual magnetization position from the image information of the magnetic sheet, it is necessary for the operator to manually move the mounting table and measure the actual magnetization position visually as in the past. Absent. Thereby, the measurement operation of the actual magnetization position can be performed in a short time and with high accuracy. As described above, according to the first aspect of the present invention, the time required for the detection operation of the position to be magnetized and the measurement operation of the actual magnetization position can be shortened, and the detection accuracy of the position to be magnetized and the actual detection time can be reduced. The measurement accuracy of the magnetization position can be improved. As a result, it is possible to detect the displacement of the magnetized position quickly and with high accuracy.
[0019]
According to a second aspect of the present invention, in the configuration of the first aspect, the step of calculating the position to be magnetized includes providing a predetermined reference portion serving as a datum separately from the magnet, Including a step of obtaining a virtual center line of the magnet based on the captured image information, and the step of detecting the actual magnetization position is a step of obtaining the center line of the actual magnetization position of the magnet based on the image information of the magnetic sheet. The step of comparing includes a step of calculating a deviation amount between the virtual center line of the magnet and the center line of the actual magnetization position of the magnet. In this way, the deviation amount of the center line of the magnetized position is easily detected by calculating the deviation amount of the virtual center line of the magnet and the center line of the actual magnetized position of the magnet. be able to.
[0020]
In the magnetizing position detection method according to claim 3, in the configuration of claim 1, the step of calculating the position to be magnetized includes providing a predetermined reference portion serving as a datum separately from the magnet, The step of obtaining the virtual center line of the magnet based on the image information taken, and the step of detecting the actual magnetized position includes the N pole side end and the S pole side end of the magnet based on the image information of the magnetic sheet. The step of comparing and including the step of detecting includes the step of calculating the distance between the virtual center line of the magnet and the N pole side end and S pole side end of the magnet. According to the third aspect of the present invention, by calculating the distance between the virtual center line of the magnet and the N pole side end and the S pole side end of the magnet, the N pole from the center position (neutral center) of the magnetized position. It is possible to easily detect the amount of deviation from the design value of the distance to the side end and the S pole side end.
[0021]
According to a fourth aspect of the present invention, the magnet position includes a rare earth magnet used in the hard disk drive device. According to the fourth aspect of the present invention, by using the magnet whose magnetization position is detected with high accuracy according to the inventions of the first to third aspects as a rare earth magnet used in the hard disk drive, the hard disk drive is highly accurate. Can be controlled. As a result, a hard disk drive having a small track width can be accurately handled.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a schematic diagram showing a configuration of a detection device used in a magnetizing position detection method according to an embodiment of the present invention. FIG. 2 is a top view showing a mounting table portion of the detection apparatus shown in FIG.
[0024]
First, with reference to FIG. 1 and FIG. 2, the detection apparatus used with the detection method of the magnetization position of this embodiment is demonstrated. This detection apparatus includes a mounting table 1, illumination means 6 for CCD image recognition, a CCD camera 7, a monitor 9, and a personal computer 11. The CCD camera 7 and the monitor 9 are connected by a cable 8, and the monitor 9 and the personal computer 11 are connected by a cable 10.
[0025]
As shown in FIGS. 1 and 2, a reference block (datum) 2 serving as a reference position of the magnet 51 is provided on the upper surface of the mounting table 1. In addition, a plurality of protrusions 3 are provided on the upper surface of the mounting table 1 for arranging the base plate 50 to which the magnets 51 are attached while maintaining the positional relationship with the datum 2. An acrylic plate 4 is attached to the mounting table 1 so as to be openable and closable with respect to the upper surface of the mounting table 1. On the inner surface of the acrylic plate 4, a magnetic sheet 5 on which a magnetic material is movably held is mounted. The magnetic sheet 5 is disposed at such a position that the magnetic sheet 5 covers the upper surface of the magnet 51 when the acrylic plate 4 is closed to the upper surface side of the mounting table 1.
[0026]
Here, since the magnetic body of the magnetic sheet 5 moves in accordance with the magnetized state of the magnet 51, the magnetized state of the magnet 51 can be determined according to the distribution state of the magnetic body. More specifically, for example, as shown in FIG. 2, when the magnet 51 is magnetized in the N pole and the S pole, a region magnetized in the N pole and a region magnetized in the S pole The magnetic material of the magnetic sheet 5 does not move to the non-magnetized region located between the two. Therefore, the magnetization position (positions of the N pole side end 51a and the S pole side end 51b) can be determined according to the distribution state of the magnetic material.
[0027]
The monitor 9 is provided to display images such as the magnetic sheet 5 and the datum 2 taken by the CCD camera 7. The personal computer 11 is provided to convert the pixel value of the shift amount detected by the monitor 9 into a unit of length. As shown in FIG. 1, the mounting table 1 is installed so as to be movable only in the X direction.
[0028]
The procedure for detecting the magnetized position using the detection apparatus configured as described above will be described in detail below.
[0029]
First, the mounting table 1 is moved to a position indicated by a two-dot chain line in FIG. Then, the acrylic plate 4 is opened upward. In this state, the base plate 50 to which the magnet 51 actually magnetized is integrally attached is mounted in a state of being positioned by the plurality of protrusions 3 (see FIG. 2). Thereafter, the acrylic sheet 4 is closed to the upper surface side of the mounting table 1, so that the magnetic sheet 5 is disposed at a position covering the magnet 51 as shown in FIG. 2. And the mounting base 1 is moved to the position of the continuous line shown in FIG.
[0030]
In this state, the CCD camera 7 photographs the datum 2, the magnet 51, and the magnetic sheet 5 on the top surface of the mounting table 1. An image taken by the CCD camera 7 is displayed on the monitor 9.
[0031]
In the monitor 9, first, the virtual center line of the magnet 51 is automatically calculated based on the image information of the datum 2.
[0032]
Next, the center line of the actual magnetization position of the magnet 51 is automatically obtained based on the image information of the magnetic sheet 5. That is, as described above, since the actual magnetization position can be determined from the distribution of the magnetic material of the magnetic sheet 5, the center line of the actual magnetization position can be determined from the image information of the magnetic sheet 5 displayed on the monitor 9. Can be easily obtained. Thereafter, a deviation amount between the virtual center line of the magnet 51 and the center line of the actual magnetization position is calculated. This deviation amount is calculated by a pixel value. The shift amount of the pixel value is converted into a unit of length by the personal computer 11. Then, by determining whether or not the deviation amount expressed in the unit of length is within a preset allowable range of the deviation amount of the center line, the non-defective product and the defective product in the magnetized state of the magnet 51 are determined. To determine.
[0033]
In the present embodiment, as described above, the virtual center line of the magnet 51 is automatically calculated based on the image information of the datum 2, so that the reference position of the magnet and the reference position on the screen as in the past are calculated. There is no need for the operator to manually move the mounting table and perform alignment by visual inspection in order to perform alignment work (operation for detecting the center line of the position to be magnetized). Thereby, the detection operation of the position to be magnetized can be performed in a short time and with high accuracy.
[0034]
Further, by automatically detecting the actual magnetized position from the image information of the magnetic sheet 5, it is not necessary for the operator to manually move the mounting table and visually measure the magnetized position as in the prior art. . Thereby, the measurement operation of the actual magnetization position can be performed in a short time and with high accuracy.
[0035]
As described above, according to the present embodiment, it is possible to reduce the time required for the work for detecting the position to be magnetized and the work for measuring the actual magnetized position, and the detection accuracy of the position to be magnetized and the actual magnetization. The position measurement accuracy can be improved. As a result, it is possible to detect the displacement of the magnetized position quickly and with high accuracy.
[0036]
Further, if the magnet 51 in which the deviation amount of the magnetization position is detected with high accuracy as described above is used as a rare earth magnet used for the voice coil motor of the hard disk drive device, the hard disk drive device is controlled with high accuracy. be able to. As a result, a hard disk drive having a small track width can be accurately handled.
[0037]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.
[0038]
For example, in the above embodiment, the deviation amount between the virtual center line of the magnet and the center line of the actual magnetization position is calculated. However, the present invention is not limited to this, and the standard value of the magnet magnetization position ( The present invention can be applied when various displacement amounts are calculated according to (spec). Specifically, by calculating the distance between the virtual center line of the magnet and the N pole side end 51a and the S pole side end 51b of the magnet 51 shown in FIG. 2, the N pole side from the center line of the magnet 51 is calculated. It is also possible to calculate a deviation amount with respect to the design value of the distance between the end portion 51a and the S pole side end portion 51b. Further, by adding the distance from the center line of the magnet 51 to the N pole side end 51a and the distance from the center line of the magnet 51 to the S pole side end 51b, the N pole side end 51a and the S pole It is also possible to calculate the distance (width) between the side end portion 51b and the deviation amount of the width with respect to the design value.
[0039]
Moreover, in the said embodiment, in order to calculate the center position of the magnet 51, the image information of the datum 2 was used, However, this invention is not limited to this, It magnetizes based on the image information of the shape itself of the magnet 51. The power position may be detected.
[0040]
【The invention's effect】
As described above, according to the present invention, compared with the case where the operator manually moves the mounting table and performs the work of detecting the position to be magnetized visually and the work of measuring the actual magnetized position, the work time Can be shortened, and the detection accuracy of the position to be magnetized can be improved. As a result, it is possible to detect the displacement of the magnetized position quickly and with high accuracy.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a configuration of a detection device used in a magnetization position detection method according to an embodiment of the present invention.
2 is a plan view showing a mounting table portion of the detection device according to the embodiment shown in FIG. 1; FIG.
FIG. 3 is a plan view showing a mounting table portion of a detection device used in a conventional method for detecting a magnetized position.
4 is a plan view for explaining a procedure for detecting a magnetization position using the conventional detection device shown in FIG. 3; FIG.
[Explanation of symbols]
1 Mounting table 2 Datum (reference block)
3 Projection 4 Acrylic plate 5 Magnetic sheet 6 Illumination means 7 CCD camera 8 Cable 9 Monitor 10 Cable 11 Personal computer 50 Base plate 51 Magnet 51a N pole side end 51b S pole side end

Claims (4)

Calculating a position where the magnet should be magnetized based on image information relating to the magnet to be inspected;
Arranging a magnetic sheet on which the magnetic material is movably held on the magnet, and detecting an actual magnetization position of the magnet based on image information obtained by photographing the magnetic sheet;
A method for detecting a magnetized position, comprising the step of comparing the calculated position to be magnetized with the detected actual magnetized position. The step of calculating the position to be magnetized includes
Providing a predetermined reference portion that becomes a datum separately from the magnet, and determining a virtual center line of the magnet based on image information obtained by photographing the reference portion;
The step of detecting the actual magnetization position includes:
Based on image information of the magnetic sheet, including a step of obtaining a center line of an actual magnetized position of the magnet,
The comparing step includes
The method for detecting a magnetized position according to claim 1, further comprising a step of calculating a deviation amount between a virtual center line of the magnet and a center line of an actual magnetized position of the magnet. The step of calculating the position to be magnetized includes
Providing a predetermined reference portion that becomes a datum separately from the magnet, and determining a virtual center line of the magnet based on image information obtained by photographing the reference portion;
The step of detecting the actual magnetization position includes:
Detecting the N pole side end and the S pole side end of the magnet based on the image information of the magnetic sheet;
The comparing step includes
The method for detecting a magnetized position according to claim 1, comprising calculating a distance between the virtual center line of the magnet and the N pole side end and the S pole side end of the magnet. The method for detecting a magnetized position according to any one of claims 1 to 3, wherein the magnet includes a rare earth magnet used in a hard disk drive.

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