JP5293163B2 - Magnetic characteristic measuring device and magnetic characteristic measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and method for measurement of magnetic characteristics capable of properly measuring the magnetic characteristics of a perpendicular magnetic recording medium. <P>SOLUTION: The magnetic characteristic measuring device A includes: an electromagnet 1 making a perpendicular magnetic field act on a measurement unit of a magnetic disk B; a variable fixed current supplying means 2 supplying a DC driving current to the electromagnet 1 in a prescribed variable range; a magnetic reading means 3 reading a leakage magnetic field from the magnetic disk B; measurement unit moving means 6 and 7 repetitively moving the measurement unit from a position opposed to magnetic poles 1A and 1B to a position opposed to the magnetic reading means 3; a current variably controlling means 8 variably controlling the DC driving current via the variable fixed current supplying means 2 whenever prescribed movement operation is performed by the measurement unit moving means 6 and 7; and a signal waveform analyzing means 10 acquiring the signal output from the magnetic reading means 3 and analyzing the signal waveform thereof whenever the prescribed movement operation is performed by the measurement unit moving means 6 and 7. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a magnetic characteristic measuring apparatus and a magnetic characteristic measuring method for measuring magnetic characteristics of a perpendicular magnetic recording medium.

  As a technique for measuring the magnetic characteristics of a magnetic member, there is one disclosed in Patent Document 1. In the technique disclosed in this document, a magnetic property of a rolled material including a magnetic material is measured using a vibrating sample magnetometer (commonly known as VSM). This vibrating sample magnetometer places a small sample in a magnetic field generated by an electromagnet, vibrates the sample with a constant amplitude and frequency, and induces the magnitude of magnetization of the sample in a detection coil. By taking it as an induced voltage, the magnetic properties of a relatively small sample are measured.

JP 2000-286112 A

  However, in the magnetic property measurement method using the above-described conventional vibrating sample type magnetometer, although the magnetic material corresponds to the sample containing the entire material uniformly, it seems that the magnetic portions are discretely formed in the nonmagnetic region. However, there is a difficulty that cannot be dealt with in a perpendicular magnetic recording medium. For example, a perpendicular magnetic recording medium includes a magnetic disk called a so-called patterned medium, in which a large number of magnetic dots as a minimum recording unit are formed in a non-magnetic region with a size of about several tens of nanometers. . With respect to such a magnetic disk, it is impossible to accurately set a target for extremely small magnetic dots and measure the magnetic characteristics thereof. Therefore, along with the development of magnetic disks such as patterned media, it has been important to realize a magnetic property measuring device that can replace the vibrating sample magnetometer.

  The present invention has been conceived under the circumstances described above, and provides a magnetic property measuring apparatus and a magnetic property measuring method capable of appropriately measuring the magnetic properties of a perpendicular magnetic recording medium. It is an issue.

  In order to solve the above problems, the present invention takes the following technical means.

According to a first aspect of the present invention, there is provided a magnetic property measuring apparatus for measuring magnetic properties of a perpendicular magnetic recording medium in which magnetic regions are discretely formed in a nonmagnetic region, the perpendicular magnetic recording medium An electromagnet that simultaneously applies a vertical magnetic field to a plurality of magnetic regions via magnetic poles at a predetermined measurement site on the surface of the surface, variable constant current supply means for supplying a DC drive current to the electromagnet in a predetermined variable range, and the vertical magnetism A magnetic reading means which is arranged opposite to the surface of the recording medium and reads the leakage magnetic field from the surface for each magnetic region, and the measurement site is repeatedly moved from a position facing the magnetic pole to a position facing the magnetic reading means. The measurement part moving means to be moved and the DC drive current are variably controlled via the variable constant current supply means each time a predetermined movement operation is performed by the measurement part moving means. Includes a variable current control means for, acquires the signals output from said magnetic read means each time the predetermined moving operation is performed by the measurement site moving means, and the signal waveform analyzing means for analyzing the signal waveform, and The signal waveform analyzing means is provided with a magnetic characteristic measuring device that generates a magnetization curve from the number of the magnetic regions in which the magnetization direction with respect to the vertical magnetic field applied by the electromagnet is reversed .

According to a second aspect of the present invention, there is provided a magnetic property measuring method for measuring magnetic properties of a perpendicular magnetic recording medium in which magnetic regions are discretely formed in a nonmagnetic region, the perpendicular magnetic recording medium A vertical magnetic field is simultaneously applied to a plurality of magnetic regions via a magnetic pole of an electromagnet at a predetermined measurement site on the surface of the magnetic recording medium, and a leakage magnetic field from the surface of the perpendicular magnetic recording medium is read on each surface of the magnetic region. On the other hand, the magnetic reading means is arranged oppositely, and the measurement site is repeatedly moved from the position facing the magnetic pole to the position facing the magnetic reading means, and is supplied to the electromagnet each time a series of moving operations are performed. the DC drive current with variable control, obtains a signal output from the magnetic reading unit, the magnetization direction with respect to the vertical magnetic field which the electromagnet is applied is inverted From the number of the serial magnetic regions to generate the magnetization curve, the magnetic characteristic measuring method such that analyzes the signal waveform is provided.

  According to the technique disclosed by the present invention, when measuring the magnetic characteristics of a perpendicular magnetic recording medium such as a patterned medium, a perpendicular magnetic field is applied to a predetermined measurement site by an electromagnet, and then the leakage magnetic field from the measurement site is measured. Read the residual magnetism. Each time such a series of operations is performed, the electromagnet changes the magnitude of the perpendicular magnetic field with respect to the perpendicular magnetic recording medium, and accordingly, the signal waveform obtained by reading the residual magnetism also changes. As a result, a plurality of signal waveforms can be obtained according to the magnitude of the vertical magnetic field, and the magnetic characteristics can be obtained by analyzing the signal waveforms of various patterns, so that the magnetic characteristics of the perpendicular magnetic recording medium are appropriately measured. be able to.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  1 to 9 show an embodiment of a magnetic property measuring apparatus according to the present invention. The magnetic characteristic measuring apparatus A of this embodiment is for measuring the magnetic characteristics of a disk-shaped magnetic disk B as a perpendicular magnetic recording medium. Typical examples of this type of magnetic disk B include a discrete track medium B1 as shown in FIG. 2A and a patterned medium B2 as shown in FIG. In the discrete track medium B1, a backing soft magnetic layer 110 is formed on a substrate 100, and a nonmagnetic region 120A and a magnetic region 120B to be a magnetic recording portion are further formed on the backing soft magnetic layer 110, and this magnetic region 120B is formed. Is formed into a strip shape along the circumferential direction of the disk. In the patterned medium B2, the magnetic regions 120B are arranged in dots so that the magnetic recording portions are scattered in the nonmagnetic regions 120A on the backing soft magnetic layer 110.

  As shown in FIG. 1, the magnetic characteristic measuring apparatus A includes an electromagnet 1, a variable constant current supply circuit 2, a magnetic head 3, a swing arm 4, a swing motor 5, a rotation motor 6, a measurement site movement control unit 7, and a variable current. A control unit 8, a recording control unit 9, and a signal waveform analysis unit 10 are provided. The electromagnet 1, variable constant current supply circuit 2, magnetic head 3, swing arm 4, swing motor 5, and rotary motor 6 are built in a main unit (not shown) that accommodates the magnetic disk B, and move the measurement site. The control unit 7, the variable current control unit 8, the recording control unit 9, and the signal waveform analysis unit 10 are realized by, for example, a computer connected to the main unit.

  The electromagnet 1 is obtained by winding a coil 11 around a U-shaped magnetic body 10 and causing a pair of magnetic poles 1A and 1B to face each other. Both ends of the coil 11 are connected to the variable constant current supply circuit 2. A magnetic disk B to be measured is disposed between the pair of magnetic poles 1A and 1B. The gap between the surface of the magnetic disk B and the magnetic poles 1A and 1B is set to 0.1 mm or less, for example. When a current is supplied to the coil 11, a magnetic field corresponding to the magnitude of the current is generated between the magnetic poles 1A and 1B, and this magnetic field acts on the magnetic disk B as a vertical magnetic field. When the direction of the current flowing through the coil is changed, the direction of the perpendicular magnetic field with respect to the magnetic disk B is also changed.

  For example, when a patterned medium B2 as shown in FIG. 3 is used as a measurement target, the vertical magnetic field of the electromagnet 1 acts on a fixed measurement section C in which a predetermined number of dot-like magnetic regions 120B are arranged in the disk circumferential direction and the disk radial direction. To do. In the figure, the magnetization direction of the magnetic region 120B is shown in white and black. When the perpendicular magnetic field of the electromagnet 1 is applied to the measurement section C in which the magnetization directions of the magnetic regions 120B are all aligned in the same direction, and the magnitude of the perpendicular magnetic field is gradually increased, the magnetization direction is reversed accordingly. The number of magnetic regions 120B also increases gradually. When the magnitude of the vertical magnetic field exceeds a predetermined level, the magnetization directions in all the magnetic regions 120B included in the measurement section C are reversed.

  The variable constant current supply circuit 2 supplies a DC drive current to the coil 11 of the electromagnet 1 within a predetermined variable range. The variable constant current supply circuit 2 supplies a direct current drive current in a state where a predetermined current value is maintained when a vertical magnetic field is applied to a predetermined measurement portion of the magnetic disk B by the electromagnet 1. On the other hand, the variable constant current supply circuit 2 can change the current value of the DC drive current or change the direction of the current for each series of measurement operations.

  The magnetic head 3 is provided at the tip of the swing arm 4 via a slider (not shown), and is disposed opposite to the surface of the magnetic disk B. The slider is for floating the magnetic head 3 on the surface of the magnetic disk B rotating at a high speed with a small flying height. The magnetic head 3 is reciprocated in the substantially radial direction of the magnetic disk B according to the swinging motion of the swing arm 4. The magnetic head 3 is equipped with a reading element and a recording element (not shown). The reading element is provided as magnetic reading means for reading a leakage magnetic field from the surface of the magnetic disk B. The recording element is provided as magnetic recording means for applying a recording magnetic field to the magnetic disk B. The reading element is connected to the signal waveform analysis unit 10, and the recording element is connected to the recording control unit 9.

  For example, when the position of the magnetic head 3 in the disk radial direction is fixed using the patterned medium B2 as shown in FIG. 4 as a measurement object, the dot-shaped magnetic region 120B is arranged along the disk circumferential direction, for example. Of the plurality of rows arranged in a line, the predetermined measurement row D facing the magnetic head 3 is acted. By moving the magnetic head 3 in the disk radial direction, a recording magnetic field can be applied to the plurality of measurement rows D. In the figure, the magnetization direction of the magnetic region 120B is shown in white and black. When a recording magnetic field is applied to a predetermined measurement column D in which the magnetization directions of the magnetic regions 120B are all aligned in the same direction, and the magnitude of the recording magnetic field is gradually increased, the magnetization direction is reversed in the measurement column D. The number of magnetic regions 120B also increases gradually. When the magnitude of the recording magnetic field exceeds a predetermined level, the magnetization directions in all the magnetic regions 120B included in the measurement sequence are reversed. However, even if a recording magnetic field having the same magnitude as the vertical magnetic field generated by the electromagnet 1 is applied to the predetermined measurement array D as shown in FIGS. 3 and 4, the magnetization direction is reversed due to the magnetic effect of the adjacent magnetic region 120B. There are also magnetic regions 120B that do not, and the measurement results may differ.

  The swing arm 4 has a slider and a magnetic head 3 at its distal end, and swings so that the distal end reciprocates in the substantially radial direction of the magnetic disk B around the base end.

  The swing motor 5 is composed of, for example, a voice coil motor, and swings the swing arm 4 so as to move the magnetic head 3 to a predetermined position in the radial direction of the magnetic disk B in response to a command from the measurement site movement control unit 7.

  The rotary motor 6 is composed of, for example, a spindle motor, and moves the measurement part of the magnetic disk B to a position facing the magnetic poles 1A and 1B or a position facing the magnetic head 3 in accordance with a command from the measurement part movement control unit 7. Thus, the magnetic disk B is rotated at a high speed.

  The measurement site movement control unit 7 moves the magnetic head 3 to a predetermined position in the radial direction of the magnetic disk B via the swing motor 5, while rotating the magnetic disk B at a high speed via the rotary motor 6, thereby The measurement site of the disk B is repeatedly moved from a position facing the magnetic poles 1A and 1B to a position facing the magnetic head 3. The control operation of the measurement site movement control unit 7 is performed by reading the magnetic head 3 from a clock signal output at a constant frequency from a clock generation circuit (not shown) or from a preamble unit or a phase servo unit formed on the magnetic disk B. This is performed by recognizing the position of each magnetic region 120B in the radial direction and circumferential direction of the magnetic disk B based on the magnetic read signal obtained through the element.

  The current variable control unit 8 is configured to control the current value or current of the DC drive current supplied to the coil 11 of the electromagnet 1 through the variable constant current supply circuit 2 every time a predetermined movement operation is performed by the measurement site movement control unit 7. Variable control of direction.

  The recording control unit 9 controls the recording element of the magnetic head 3 to generate a recording magnetic field having a predetermined magnitude. The recording control unit 9 has a function of changing the drive current for the recording element so that the recording magnetic field for the magnetic disk B can be changed. This drive current is variably controlled as a direct current by the recording control unit 9 and also variably controlled as an alternating current.

  The signal waveform analysis unit 10 obtains a magnetic read signal output from the reading element of the magnetic head 3 according to the residual magnetic field from the surface of the magnetic disk B by fast Fourier transform, and analyzes the signal waveform.

  For example, as shown in FIG. 5, the patterned media B2 is used as a measurement target, and the patterned media B2 is initialized by setting the strength of the vertical magnetic field by the electromagnet 1 to −20 kOe. Thereafter, the preamble part and phase servo part of the patterned medium B2 are used as measurement parts, and the vertical magnetic field is changed from 0 kOe to +15 kOe and +15 kOe at a predetermined change rate each time these measurement parts are located opposite to the magnetic poles 1A and 1B. It is changed sequentially from 0 kOe, 0 kOe to −15 kOe, and from −15 kOe to 0 kOe. The residual magnetic field is read by the reading element of the magnetic head 3 in the preamble portion and the phase servo portion to which the vertical magnetic field acts in this way. Thereby, a magnetic read signal as shown in the figure as an example is obtained. The signal waveform analysis unit 10 normalizes the strength of the residual magnetic field from the magnetic read signal, thereby generating a magnetization curve indicating a change tendency of the saturation magnetization (Ms) according to the strength of the vertical magnetic field (H). Such a magnetization curve is obtained as an analysis result indicating the magnetic characteristics of the preamble portion and the phase servo portion, and is output from a computer display device or printing device (not shown).

  On the other hand, in the example shown in FIG. 6, the magnetic recording part of the patterned medium B2 is used as a measurement site, the strength of the vertical magnetic field is initialized to +20 kOe, and then the vertical magnetic field is changed in the same pattern as described above. A magnetic read signal as shown in the figure is obtained. With respect to this magnetic read signal, each of a portion having a maximum value and a portion having a minimum value of the signal waveform is indicated by a black dot mark and a white dot mark. The positions of these dot marks are recognized as the positions of the magnetic regions 120B in the magnetic recording unit. For example, the signal waveform analysis unit 10 counts the number of magnetic regions 120B in which the magnetization direction is reversed by changing from a black dot mark to a white dot mark. As a result, a curve showing the tendency of change in the number of magnetization direction inversions according to the strength of the vertical magnetic field (H) is generated, and this curve is obtained as equivalent to the magnetization curve. A curve equivalent to such a magnetization curve is also an analysis result indicating the magnetic characteristics of the magnetic recording unit, and is output from a computer display device or printing device (not shown).

  Next, the operation procedure of the magnetic property measuring apparatus A will be described with reference to FIGS. Note that the patterned medium B2 is applied as an example of a measurement target in the following description.

  First, as shown in FIG. 7, the measurement site movement control unit 7 rotates the patterned medium B2 and moves the magnetic head 3 in the radial direction of the disk. At this time, the magnetic reading obtained via the signal waveform analysis unit 10 is obtained. By performing predetermined signal processing on the signal based on the clock signal, the preamble portion, the phase servo portion, and the magnetic recording portion are recognized as measurement sites. Thereafter, the measurement site movement control unit 7 creates a first measurement routine that associates the movement of the measurement site with the method of changing the vertical magnetic field (S1). According to the first measurement routine, for example, the magnetic head 3 is positioned at a predetermined position in the disk radial direction, and the action of the vertical magnetic field and the leakage magnetic field are applied to one or a plurality of measurement sites in the disk circumferential direction corresponding to the position. A series of measurement operations such as reading, acting by changing the vertical magnetic field, and reading the leakage magnetic field again are repeatedly executed. Such a first measurement routine also defines a control procedure for repeatedly executing a series of measurement operations after the magnetic head 3 is positioned at a different position in the disk radial direction. Based on such a first measurement routine, even in the fine magnetic region 120B in the patterned medium B2, the magnetic characteristics are efficiently and accurately measured.

  Next, the measurement site movement control unit 7 moves the predetermined measurement site recognized based on the first measurement routine to a position facing the magnetic poles 1A and 1B (S2).

  When the predetermined measurement part comes to a position facing the magnetic poles 1A and 1B of the electromagnet 1, the current variable control unit 8 instructs the variable constant current supply circuit 2 to have a predetermined current value determined by the first measurement routine. As a result, a vertical magnetic field having a predetermined magnitude determined in the first measurement routine is generated between the magnetic poles 1A and 1B, and this vertical magnetic field acts on a predetermined measurement site (S3).

  After the vertical magnetic field acts on the predetermined measurement site, the measurement site movement control unit 7 moves the measurement site to a position facing the magnetic head 3 based on the first measurement routine (S4).

  When the measurement part comes to a position facing the magnetic head 3, the reading element reads the residual magnetism as a leakage magnetic field from the measurement part, and the signal waveform analysis unit 10 acquires the magnetic read signal output from the reading element. (S5).

  The series of measurement operations from S2 to S5 is performed in a state where the magnitude of the vertical magnetic field is maintained at a constant level, and such measurement operation is performed a predetermined number of times by changing the vertical magnetic field for the same measurement site. At the same time, the same measurement operation is performed a predetermined number of times for the measurement sites at different positions in the disk radial direction, thereby completing the first measurement routine. When such a first measurement routine is completed (S6: YES), the signal waveform analysis unit 10 analyzes the signal waveform acquired for each different measurement site based on the vertical magnetic field changed within a predetermined variable range. (S7). As described above, the signal waveforms as shown in FIGS. 5 and 6 are obtained.

  In S6, when the first measurement routine is not completed (S6: NO), the current variable control unit 8 informs the variable constant current supply circuit 2 that the current value is changed to the predetermined current value determined in the first measurement routine. The vertical magnetic field generated between the magnetic poles 1A and 1B is changed to a predetermined level determined by the first measurement routine (S9). Thereafter, the process proceeds to S2 again.

  When the analysis of all the signal waveforms is completed, the signal waveform analysis unit 10 obtains an analysis result obtained according to the vertical magnetic field by the electromagnet 1 as a magnetization curve as shown in FIGS. 5 and 6 and displays this magnetization curve. The data is output to the apparatus or the printing apparatus (S8). Thereby, the magnetic characteristic measurement process using the electromagnet 1 is completed.

  Thereafter, as shown in FIG. 8, a magnetic characteristic measurement process using the recording element of the magnetic head 3 is performed. That is, the measurement site movement control unit 7 creates a second measurement routine in which the movement of the measurement site is associated with how to change the recording magnetic field of the recording element (S11). This second measurement routine has the same contents as the first measurement routine except that, for example, the variable range of the drive current for the recording element is different.

  Next, the measurement site movement control unit 7 moves the predetermined measurement site recognized based on the second measurement routine to a position facing the magnetic head 3 (S12).

  When a predetermined measurement site comes to a position facing the magnetic head 3, the recording control unit 9 supplies a drive current having a predetermined magnitude determined by the second measurement routine to the recording element of the magnetic head 3. As a result, a recording magnetic field having a predetermined magnitude determined in the second measurement routine acts on the measurement site (S13).

  After the recording magnetic field acts on a predetermined measurement site, the measurement site is moved to a position facing the reading element of the magnetic head 3 based on the second measurement routine. Thereafter, the reading element reads the magnetism recorded from the measurement site, and the signal waveform analysis unit 10 acquires the magnetic reading signal output from the reading element (S14).

  The series of measurement operations of S12 to S14 is also performed in a state where the magnitude of the recording magnetic field is maintained at a constant level, and such measurement operation is performed a predetermined number of times by changing the recording magnetic field for the same measurement site. At the same time, the second measurement routine is completed by executing the same measurement operation a predetermined number of times for measurement sites at different positions in the disk radial direction. When such a second measurement routine is completed (S15: YES), the signal waveform analysis unit 10 analyzes the signal waveforms acquired for different measurement sites based on the recording magnetic field changed within a predetermined variable range. (S16).

  In S15, when the second measurement routine has not ended (S15: NO), the recording control unit 9 changes the drive current for the recording element to a predetermined current value determined in the second measurement routine, and the recording element The magnitude of the recording magnetic field is changed to a predetermined level determined in the second measurement routine (S20). Thereafter, the process proceeds to S12 again.

  When the analysis of all the signal waveforms is completed, the signal waveform analysis unit 10 obtains an analysis result obtained according to the recording magnetic field by the recording element as a magnetization curve in the same procedure as described above, and displays this magnetization curve in the display device. Alternatively, the data is output to the printing apparatus (S17).

  Further, the signal waveform analysis unit 10 compares the magnetization curve obtained as an analysis result by the electromagnet 1 with the magnetization curve obtained as an analysis result by the recording element (S18). As the analysis result, for example, measurement information corresponding to the measurement section C and the measurement row D as shown in FIGS. 3 and 4 is obtained, so that the magnetization curves are compared with different tendencies. As shown in FIG. 9, the signal waveform analysis unit 10 supplies a DC drive current to the recording element to supply a measurement result obtained according to the DC recording magnetic field of the recording element and an AC drive current to the recording element. Thus, the measurement result obtained according to the AC recording magnetic field of the recording element can be compared, and the comparison result between the DC recording magnetic field and the AC recording magnetic field can be obtained as measurement information.

  Thereafter, the signal waveform analysis unit 10 outputs various measurement information as a comparison result to the display device or the printing device (S19). Thereby, the magnetic characteristic measurement process using the recording element is completed following the magnetic characteristic measurement process using the electromagnet 1.

  Therefore, according to the magnetic property measuring apparatus A of the present embodiment, when measuring the magnetic properties of the magnetic disk B such as the patterned medium B2, for example, the vertical magnetic field is applied to the predetermined measurement site by the electromagnet 1, and then the measurement is performed. The residual magnetism is read as a leakage magnetic field from the part. Furthermore, a residual magnetic field due to the recording magnetic field can be read from the measurement site by applying a recording magnetic field via the recording element of the magnetic head 3. As a result, various signal waveforms can be obtained according to the magnitude of the vertical magnetic field and the magnitude of the recording magnetic field, and by analyzing the signal waveforms of various patterns, a magnetization curve corresponding to the measurement site can be obtained as a magnetic characteristic. Therefore, the magnetic characteristics of the magnetic disk B can be measured appropriately.

  In addition, this invention is not limited to said embodiment.

  The configuration shown in the above embodiment is merely an example, and the design can be changed as appropriate according to the specification.

  For example, the magnetic head may be provided with only the reading element, and only the magnetic characteristic measurement process using an electromagnet may be performed.

  As long as the measurement site can be measured by specifying at least one location, a specific position along either the disk circumferential direction or the disk radial direction may be set as the measurement site.

  When the medium to be measured is not disk-like and is not suitable for rotation, the electromagnet or the magnetic head may be moved alternately with respect to the measurement site.

  When measuring magnetic characteristics with a recording element provided in a magnetic head, an alternating magnetic field that reverses the direction of the magnetic field at a predetermined frequency is generated in the recording element, and a signal waveform obtained accordingly is analyzed. Also good. Magnetic characteristics may be measured with the magnetic head in contact with the surface of the magnetic disk.

  As the magnetic characteristic measurement process, a process using a recording element may be executed first, followed by a process using an electromagnet.

It is a block diagram which shows one Embodiment of the magnetic characteristic measuring apparatus which concerns on this invention. It is a notch perspective view which shows the magnetic disc applicable to the magnetic characteristic measuring apparatus of FIG. It is explanatory drawing for demonstrating the magnetic effect | action of the electromagnet with respect to a pattern medium. It is explanatory drawing for demonstrating the magnetic effect | action of the magnetic head with respect to a pattern medium. It is explanatory drawing for demonstrating an example of the measurement result by the magnetic characteristic measuring apparatus of FIG. It is explanatory drawing for demonstrating an example of the measurement result by the magnetic characteristic measuring apparatus of FIG. It is a flowchart which shows the magnetic characteristic measurement process which mainly used the electromagnet. It is a flowchart which shows the magnetic characteristic measurement process using a magnetic head. It is explanatory drawing for demonstrating the magnetic effect | action of the magnetic head with respect to a pattern medium.

Explanation of symbols

A Magnetic characteristic measuring device B, B1, B2 Magnetic disk (perpendicular magnetic recording medium)
DESCRIPTION OF SYMBOLS 1 Electromagnet 1A, 1B Magnetic pole 2 Variable constant current supply circuit (variable constant current supply means)
3 Magnetic head (magnetic reading means, magnetic recording means)
4 Swing arm (Measuring part moving means, magnetic head moving mechanism)
5 Swing motor (measuring part moving means, magnetic head moving mechanism)
6 Rotating motor (Measuring part moving means)
7 Measurement part movement control part (Measurement part movement means)
8 Current variable control unit (Current variable control means)
9 Recording control section 10 Signal waveform analysis section (signal waveform analysis means)

Claims (4)

A magnetic property measuring apparatus for measuring magnetic properties of a perpendicular magnetic recording medium in which magnetic regions are discretely formed in a nonmagnetic region,
An electromagnet that causes a perpendicular magnetic field to act on a plurality of magnetic regions simultaneously via magnetic poles at a predetermined measurement site on the surface of the perpendicular magnetic recording medium;
Variable constant current supply means for supplying a DC drive current to the electromagnet in a predetermined variable range;
A magnetic reading means disposed opposite to the surface of the perpendicular magnetic recording medium and reading a leakage magnetic field from the surface for each magnetic region;
A measurement part moving means for repeatedly moving the measurement part from a position facing the magnetic pole to a position facing the magnetic reading means;
Current variable control means for variably controlling the DC drive current via the variable constant current supply means each time a predetermined movement operation is performed by the measurement site moving means;
A signal waveform analyzing means for obtaining a signal output from the magnetic reading means each time a predetermined moving operation is performed by the measurement site moving means, and analyzing the signal waveform;
Equipped with a,
The apparatus for measuring magnetic characteristics, wherein the signal waveform analyzing means generates a magnetization curve from the number of the magnetic regions in which the magnetization direction with respect to a perpendicular magnetic field applied by the electromagnet is reversed .   2. The magnetic characteristic measuring apparatus according to claim 1, wherein a disk-shaped magnetic disk is applied as the perpendicular magnetic recording medium, and the measurement site moving means includes a rotation motor that rotates the magnetic disk.   The magnetic reading means is mounted on a magnetic head, and the magnetic head is mounted with magnetic recording means for applying a recording magnetic field to the magnetic disk for each magnetic region, and the signal waveform analyzing means The magnetic characteristic measuring apparatus according to claim 1, having a function of comparing a signal waveform obtained according to a perpendicular magnetic field of the electromagnet and a signal waveform obtained according to a recording magnetic field of the magnetic recording means. A magnetic property measurement method for measuring magnetic properties of a perpendicular magnetic recording medium in which magnetic regions are discretely formed in a nonmagnetic region,
A perpendicular magnetic field is simultaneously applied to a plurality of magnetic regions through a magnetic pole of an electromagnet at a predetermined measurement site on the surface of the perpendicular magnetic recording medium, and a leakage magnetic field from the surface of the perpendicular magnetic recording medium is read for each magnetic region. The magnetic reading means is arranged opposite to the surface as
The measurement site is repeatedly moved from a position facing the magnetic pole to a position facing the magnetic reading means, and the direct current drive current supplied to the electromagnet is variably controlled each time a series of movement operations are performed. A signal output from the magnetic reading means is acquired , and the signal waveform is analyzed so as to generate a magnetization curve from the number of the magnetic regions in which the magnetization direction with respect to the perpendicular magnetic field applied by the electromagnet is reversed. , Magnetic property measurement method.

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