JP2008269717A - Method for measuring flying height of magnetic head, magnetic storing system, and instrument for measuring flying height of magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring flying height of magnetic head, and an instrument for measuring fying height of magnetic head which precisely measures the flying height of the magnetic head based on data obtained by reproducing data written in a servo area on the surface of a medium and predetermined pattern data written in a predetermined area other than the servo area, and to provide a magnetic storing system thereof. <P>SOLUTION: An FFT processing section 180 obtains, by the magnetic head 160, first and second data reproduced from one or more servo areas and the data areas in which two or more pattern data are written, obtains third data by substituting the first data with other data, and combines at least two or more second data and one or more substituted third data as a series of data to apply Fourier transform to the series of data. Then a flying height calculating section 120b calculates a relative change of the flying height of the magnetic head 170 or absolute value of the flying height based on the result of the Fourier transform. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for measuring a flying height of a magnetic head, and in particular, data written in a servo area on a medium surface of a medium for storing data and a predetermined pattern written in a predetermined area excluding the servo area. The present invention relates to a magnetic head flying height measuring method, a magnetic storage device, and a magnetic head flying height measuring device for measuring a flying height of a magnetic head based on data obtained by reproducing data.

In a magnetic storage device such as a magnetic disk device, a magnetic head (or head slider) is levitated to a predetermined height on the medium surface by using a mechanism of an air bearing. The flying height at this time is referred to as the flying height. This flying height is a product currently shipped from the factory and has a very small value of about 10 nm. In order to increase the recording density as a recording apparatus, it is not possible to reduce the flying height. Therefore, it is required to further reduce the flying height.
As a technique for controlling the flying height of the magnetic head, there is a technique for finely controlling the flying height of the magnetic head by embedding a heater in a slider and energizing the heater (see, for example, Patent Document 1 below).
As a technique for calculating the flying height of the magnetic head, for example, data of a certain pattern is written on the surface of a medium such as a magnetic disk, and the relative change in the flying height of the magnetic head (or based on the reproduction signal) (or There is a technique for calculating the absolute value of the flying height (see, for example, Patent Documents 2 to 5 below).

FIG. 9 is a diagram showing a data area and a servo area on the magnetic disk.
In order to position the magnetic head of the magnetic disk device with respect to the magnetic disk, servo areas are alternately formed on the magnetic disk as shown in FIG. 9A. Since the servo area is arranged corresponding to the constant rotation angle of the medium, the servo area and the data area are mixed with each other at regular intervals (appear at a constant cycle). In a typical example, the servo areas are arranged at intervals of 1/128 to 1/256. FIG. 9B is a diagram illustrating a configuration example of the servo area illustrated in FIG. In the servo area on the magnetic disk, as shown in FIG. 9B, a preamble area A, a servo mark area B, and a servo data area C are partitioned in order from the upstream side. In the preamble region A, positive and negative magnetic poles are alternately formed at uniform intervals along the circumferential direction. Servo marks are arranged in the servo mark area. In the servo data area C, magnetic poles are formed in a predetermined pattern that changes in the radial direction. In a magnetic disk (HDD), a synchronization signal is obtained from magnetic information read in the preamble area. The magnetic disk device reads magnetic information from the servo data area when the magnetic head crosses the position of the servo mark, and accurately positions the magnetic head on the recording track based on the read magnetic information. .

The conventional techniques described in Patent Documents 2 to 5 described above are all obtained by reading and reproducing predetermined pattern data written in the data area between the servo areas described above with a magnetic head. The flying height of the magnetic head has been calculated based on the result of Fourier transformation of the signal.
JP-A-5-20635 Japanese Patent Publication No. 7-1618 Japanese Patent No. 2711207 JP 2004-14092 A JP 2005-78795 A

  Usually, the flying height fluctuation of the magnetic head often vibrates at a resonance frequency of 75 kHz to 300 kHz due to the balance between the air film rigidity and the slider mass. When the flying height of the magnetic head fluctuates, whether the center frequency of vibration is about 70 kHz to 90 kHz, which is the center frequency of vibration in the roll direction, or about 125 kHz to 150 kHz, which is the center frequency of vibration in the pitch direction Sometimes you want to distinguish. This is because the policy for suppressing the vibration differs depending on which direction the center frequency of the vibration indicates the center frequency of the vibration.

10A and 10B are diagrams for explaining an example of the operation of the prior art. FIG. 10A shows a data area and a servo area on the magnetic disk, and FIGS. 10B and 10C show fluctuations in the flying height of the magnetic head.
In the above prior art, the fluctuation of the flying height of the magnetic head is calculated based on the reproduction signal of the pattern data written in the data area between the servo areas. In this case, the maximum length of one pattern data is shown in FIG. This is the interval (1 sector length) between the servo areas shown in 10 (A).

In this case, as shown in FIG. 10B, when the fluctuation cycle of the flying height of the magnetic head is short, the flying height fluctuation of the magnetic head can be obtained based on the reproduction signal of one pattern data. It is. That is, when the fluctuation period of the head flying height is shorter than the time for the magnetic head to pass one sector length, the head flying height fluctuates from the maximum value to the minimum value within the time for the magnetic head to pass one sector length. Therefore, the fluctuation amount of the flying height of the magnetic head can be obtained based on the reproduction signal of one pattern data.
However, as shown in FIG. 10C, when the fluctuation period of the head flying height is longer than the time for the magnetic head to pass one sector length, the magnetic head is changed based on the reproduction signal of one pattern data. The amount of change in the flying height cannot be determined.

Conventionally, since the rotational speed of the medium was relatively low (for example, about 7200 rpm), it was possible to detect a variation in the head flying amount having a certain frequency (period) to some extent based on the reproduction signal of one pattern data. .
However, when the rotational speed of the medium is large as in a recent magnetic disk device, the time required for the magnetic head to pass one sector length is short, so that the fluctuation cycle is long based on the reproduction signal of one pattern data (that is, It is not possible to detect fluctuations in the head flying height (of low frequency). As a result, the frequency resolution after the Fourier transform operation of the pattern data is deteriorated.
For example, when one servo mark is arranged in the servo area on 1/256 revolutions with a 15,000 rpm machine, the servo mark appears once every approximately 15.6 microseconds on the time axis. Even when the data area is designed to be maximized, for example, the maximum length of one data area is limited to about 12 microseconds in terms of time. When the maximum length of one data area is about 12 microseconds, the frequency resolution after Fourier analysis is about 83 kHz. As a result of the analysis, the next to 0 kHz (= DC) is the vibration component intensity of 83 kHz, and the next. Provides a vibration component intensity of 166 kHz. This makes it impossible to distinguish between the above-described vibration of about 70 kHz to 90 kHz and the vibration of about 125 kHz to 150 kHz.

  On the other hand, conventionally, the data written in the servo area shown in FIG. 10A described above and a plurality of pattern data written in the data area arranged across the servo area are continuously reproduced. When this signal is Fourier-calculated to calculate the flying height of the magnetic head, the data written in the servo area acts as a large noise, and the sensing accuracy of the flying height of the magnetic head is remarkably deteriorated.

  The present invention has been made in order to solve the above-described problem, and a servo area and a data area are alternately and repeatedly arranged on the medium surface, and a predetermined area excluding data and the servo area written in the servo area. Of a magnetic head flying height measuring method, a magnetic storage device, and a magnetic head flying height measuring device for accurately measuring the flying height of a magnetic head based on data obtained by reproducing predetermined pattern data written in For the purpose of provision.

  In the present invention, the flying height is calculated by a method as shown in FIG. That is, for example, data written in one servo area shown in FIG. 6A and a plurality of data (two in the example shown in FIG. 6A) arranged across the servo area. The pattern data written in the area is read, and each read data is reproduced. Then, the signal read from the servo area and reproduced is replaced with a predetermined value (for example, zero). Then, the flying height of the magnetic head is calculated based on the Fourier transform calculation result of the replaced signal and the reproduction signal of the pattern data written in the data area. According to the present invention, by adopting the above-described method, it is possible to prevent the data portion written in the servo area from being adversely affected as noise, and to improve the frequency resolution.

  The case where one servo mark is arranged on 1/256 revolutions with a 15,000 rpm machine will be described. Pattern data written in two data areas shown in FIG. 6A and one servo area are written. In the example of reading the read data, the frequency resolution obtained according to the present invention is 36 kHz. That is, since the vibration component intensity of 36, 72, 108, 144, and 180 kHz is obtained in order after 0 kHz (= DC), the above-described vibration of about 70 kHz to 90 kHz is distinguished from the vibration of about 125 kHz to 150 kHz. can do. In the present invention, the number of data areas to be read for measuring the flying height of the magnetic head can be any number (N) as long as it is plural. For example, by making two servo areas and three data areas to be read, or by making three servo areas and four data areas to be read, vibrations at a lower frequency can be detected, The frequency resolution can be further improved. As a result, it is possible to accurately distinguish two different vibrations that are closer in frequency.

  In the present invention, as described above, the signal read and reproduced from the servo area is replaced with, for example, zero, but the signal read and reproduced from the data area and the data replaced with zero (zero data) are replaced with each other. Data discontinuity occurs at the boundary. In the present invention, in order to prevent the discontinuity of the data from acting as noise during the Fourier transform operation, a transition region is provided at the boundary between the data read and reproduced from the data region and zero data, The data read from the data area and reproduced and the zero data are continuously changed. Specifically, a predetermined window function is applied to part or all of the data read from the data area and reproduced.

That is, this invention solves the said subject as follows.
(1) A magnetic head in a magnetic storage device having a medium for storing data, and a head for writing the data to the medium as a signal, and recording and reproducing the signal on the medium by magnetic means Use the flying height measurement method. Then, servo areas and data areas are alternately and repeatedly arranged on the medium surface, and predetermined pattern data is written in a predetermined area excluding the servo area, and the one or more servo areas and two areas are written by the magnetic head. Read the data of the area in which the pattern data is written, reproduce the first and second data, respectively, replace the first data with other data to obtain the third data, and at least Two or more of the second data and the one or more of the replaced third data are used as a series of data, and the relative change in the flying height of the magnetic head, or the flying height based on the series of data. The absolute value of is calculated.
(2) A Fourier transform operation is performed on the series of data to obtain a primary or multi-order frequency component, and the flying height of the magnetic head based on the obtained amplitude of the primary or multi-order frequency component Relative change of, or absolute value of flying height is calculated.
(3) Multiplying at least a part of the reproduced second data by a predetermined window function for continuously transitioning the second data and the obtained third data; The second data multiplied by the predetermined window function and the third data are set as the series of data.
(4) There is provided a magnetic storage device having a medium for storing data and a head for writing the data as a signal on the medium, and recording and reproducing the signal on the medium by magnetic means. Servo areas and data areas are alternately and repeatedly arranged on the medium surface, and predetermined pattern data is written in predetermined areas excluding the servo areas. The magnetic storage device includes a magnetic head flying height calculation unit, and the magnetic head flying height calculation unit reproduces each of the one or more servo areas and two or more pattern data written by the magnetic head. Obtained first and second data, replace the first data with other data to obtain third data, and replace at least two or more of the second data with the second data Using one or more of the third data as a series of data, a relative change in the flying height of the magnetic head or an absolute value of the flying height is calculated based on the series of data.
(5) A device for measuring the flying height of the magnetic head is provided. The apparatus for measuring the flying height of the magnetic head described above is a device in which servo areas and data areas are alternately and repeatedly arranged on the medium surface of the medium for storing data reproduced by the magnetic head, and the data written in the servo areas. A predetermined pattern data written in a predetermined area excluding the servo area, and a first and a second pattern data respectively received from the received one or more servo areas and the two or more pattern data. The second data is obtained and the first data is replaced with other data to obtain third data. At least two or more second data and the replaced third data are obtained. The relative change in the flying height of the magnetic head or the absolute value of the flying height is calculated based on the series of data.

The present invention can achieve the following effects.
(1) The present invention reads the data of one or more servo areas on the medium surface and the area where two or more pattern data are written, respectively, and reproduces the first and second data, respectively. Is replaced with other data to obtain third data, and at least two or more of the second data and one or more of the replaced third data are set as a series of data. Based on this series of data, the relative change in the flying height of the magnetic head or the absolute value of the flying height is calculated. According to the present invention, a Fourier transform operation is performed on the series of data to obtain a primary or multiple order frequency component, and the magnetic head is based on the obtained amplitude of the primary or multiple order frequency component. Calculate the relative change in the flying height of, or the absolute value of the flying height.
Therefore, according to the present invention, it is possible to detect a continuous vibration (a vibration having a low frequency) whose wavelength is longer than one sector (one data area), and to greatly improve the frequency resolution. Become. In addition, according to the present invention, data read from the servo area is replaced with other data, so that data written in the servo area during the Fourier transform processing is prevented from acting as a large noise. be able to. As a result, the flying height of the magnetic head can be accurately measured.
(2) The present invention provides a predetermined window function for continuously transitioning the second data and the obtained third data with respect to at least a part of the reproduced second data. And the second data multiplied by the predetermined window function and the third data are used as the series of data. Therefore, according to the present invention, it is possible to prevent the occurrence of noise due to the discontinuity of the data to be calculated in the Fourier transform calculation.
(3) Based on the flying height of the magnetic head measured according to the present invention, the flying height of the magnetic head is accurately controlled by adjusting the gap between the magnetic head and the magnetic disk to a predetermined value. can do. For example, it is possible to cancel the resonance vibration between the magnetic head and the magnetic disk.
As described above, due to the effects (1) to (3). The flying height of the magnetic head can be further reduced, and as a result, the recording density of the storage device can be increased.

  FIG. 1 is a diagram showing an example of the configuration of a magnetic storage device of the present invention. The magnetic storage device 100 includes a magnetic disk 170 that is a medium for storing data, and a magnetic head 160 for writing the data as a signal to the magnetic disk 170, and the magnetic signal is stored in the magnetic disk 170 using magnetic means. It is a processing device that records and reproduces by the The magnetic storage device 100 includes an interface unit 110, a control unit 120, a motor driver unit 130, a spindle motor 140, a voice coil motor 150, a magnetic head 160, a magnetic disk 170, and FFT (Fast Fourier Transform) processing. Part 180.

  The interface unit 110 is a processing unit that is connected to a host computer (not shown) and executes data communication with the host computer using a predetermined communication protocol. The motor driver unit 130 is a processing unit that controls the spindle motor 140 and the voice coil motor 150 based on a command output from the control unit 120. The spindle motor 140 is a motor that rotates the magnetic disk 170 at a predetermined rotational speed based on a command output from the motor driver unit 130. The voice coil motor 150 is a motor that moves the magnetic head 160 attached to the tip of the arm based on a command output from the motor driver unit 130.

  The magnetic disk 170 is a recording medium in which a thin disk (disk) made of glass or metal is coated with a magnetic material. When recording information on the magnetic disk 170, a magnetic field from the magnetic head 160 is irradiated to a recording area for recording information on the magnetic disk 170 to change the magnetization state of the magnetic material of the magnetic disk 170. To record information. When information is read from the magnetic disk 170, the magnetic head 160 is moved to a recording area on the magnetic disk 170 to be read, the magnetization state of the magnetic material of the magnetic disk 170 is read, and the information is reproduced.

  The FFT processing unit 180 acquires a signal read from the magnetic disk 170 by the magnetic head 160 and executes a Fourier transform operation. Specifically, the FFT processing unit 180 uses the magnetic head 160 to reproduce first and second data respectively reproduced from one or more servo areas and two or more data areas in which predetermined pattern data is written. And obtaining the third data by replacing the first data with other data, and at least two or more of the second data and the one or more of the replaced third data. As a series of data, a Fourier transform operation is performed on the series of data, and a result of the Fourier transform operation is output to the control unit 120. The FFT processing unit 180 includes a gate circuit 181 to be described later with reference to FIG. 5, and uses the gate circuit 181 to convert the first data into other data to obtain third data.

According to an embodiment of the present invention, the FFT processing unit 180 obtains a primary or multi-order frequency component as a result of the Fourier transform calculation, and an amplitude level (for example, the primary or multi-order frequency component) (for example, The amplitude level of the primary frequency component and the amplitude level of the third harmonic component) may be output.
Further, according to an embodiment of the present invention, the FFT processing unit 180 applies the second data and the obtained third data to at least a part of the reproduced second data. Multiplying a predetermined window function for continuous transition, the second data multiplied by the predetermined window function, and the third data as the series of data, Fourier transform is performed on the series of data. You may make it perform conversion operation.

The control unit 120 controls the writing / reading of data to / from the magnetic disk 170 and calculates the flying height of the magnetic head 160 based on the Fourier transform calculation result by the FFT processing unit 180. Further, the control unit 120 adjusts the gap between the magnetic head 160 and the magnetic disk 170 to a predetermined value based on the calculated flying height of the magnetic head 160.
The control unit 120 includes a read / write processing unit 120a, a flying height calculation unit 120b, an energization control unit 120c, and a driver control unit 120e. The read / write processing unit 120a writes or reads data to or from the magnetic disk 170 based on a write request or read request from the host computer. Further, the read / write processing unit 120a writes predetermined pattern data in the data area of the magnetic disk 170 in advance in accordance with a command from the host computer.

The flying height calculation unit 120b calculates a relative change in the flying height of the magnetic head 170 or an absolute value of the flying height based on the Fourier transform calculation result output from the FFT processing unit 180. That is, the FFT processing unit 180 and the flying height calculation unit 120b are respectively reproduced by the magnetic head 160 from the one or more servo areas and the two or more data areas in which predetermined pattern data is written. 2 is obtained, the first data is replaced with other data to obtain third data, and at least two or more of the second data and the one or more of the replaced first data are obtained. 3 is a magnetic head flying height calculation means for calculating a relative change in the flying height of the magnetic head 160 or an absolute value of the flying height based on the series of data.
According to the embodiment of the present invention, the flying height calculation unit 120b may change the flying height of the magnetic head 170 based on the amplitude level of the first-order or multiple-order frequency components output by the FFT processing unit 180. Or the absolute value of the flying height.

  The driver control unit 120e controls the rotation speed of the magnetic disk 170 by outputting a command to the motor driver unit 130 and driving the spindle motor 140. Further, the driver control unit 120e outputs a command to the motor driver unit 130, drives the voice coil motor 150, and moves the magnetic head 160. The energization control unit 120c sets a gap between the magnetic head 160 and the magnetic disk 170 based on a relative change in the flying height of the magnetic head 160 calculated by the flying height calculation unit 120b or an absolute value of the flying height. The magnetic head 160 is energized with a current of a magnitude necessary to adjust the value. That is, the energization control unit 120c expands the magnetic pole tip by energizing the magnetic pole tip of the magnetic head 160 to generate heat, and adjusts the gap between the magnetic head 160 and the magnetic disk 170 to a predetermined value.

  The read / write processing unit 120a, the FFT processing unit 180, and the flying height calculation unit 120b in FIG. 1 constitute a flying height measuring device 200 for the magnetic head. The magnetic head flying height measuring apparatus 200 receives the data written in the servo area of the magnetic disk 170 reproduced by the magnetic head 160 and the predetermined pattern data written in the predetermined data area excluding the servo area. First and second data are obtained from the received data written in one or more servo areas and the two or more pattern data, respectively. Further, the flying height measuring device 200 of the magnetic head obtains third data by replacing the first data with other data, and at least two or more of the second data and the one of the replaced ones. Using at least two pieces of the third data as a series of data, a relative change in the flying height of the magnetic head or an absolute value of the flying height is calculated based on the series of data.

  FIG. 2 is a diagram showing an example of the magnetic head described above with reference to FIG. As shown in FIG. 2, in this magnetic head 160, a lower magnetic pole 2, a thin film coil 4 formed via an insulator layer 3, an upper magnetic pole 5, and a protective layer 6 are sequentially formed on a substrate 1. In particular, since the thin film resistor 10 is formed inside the insulator layer 3, when the thin film resistor 10 is energized to generate heat, both the magnetic poles 2, 5 and the insulator layer 3, the substrate 1 and the protection Due to the difference in thermal expansion coefficient with the layer 6, the magnetic pole tip 7 protrudes as shown by the dotted line in FIG. That is, the energization control unit 120c can control the amount of protrusion of the magnetic pole tip 7 by controlling the current flowing through the thin film resistor 10.

  Next, an example of calculation processing of the flying height of the magnetic head 160 by the flying height calculation unit 120b will be described. The flying height of the magnetic head 160 can be calculated by the following Wallace relational expression.

  Here, each code | symbol (a, d) shown to Formula (1) is demonstrated. 3 and 4 are explanatory diagrams for explaining the relational expression of Wallace.

As shown in FIG. 3, the symbol d shown in the equation (1) includes HOC (Head Over Coat), PTR (Pole Tip Recession), FH (Flying Height), DOC (Disk Over Coat), and ML ( The value obtained by adding the value obtained by halving the (Magnetic Layer). Further, as shown in FIG. 4, the symbol a shown in the equation (1) is a transition region width in which the signal intensity on the magnetic disk 170 changes, that is, a transition parameter. A reference value (for example, a value at the time when the gap between the magnetic head 160 and the magnetic disk 170 becomes a predetermined size) is substituted for each code related to the subscript ref (reference). The flying height calculation unit 120b obtains this reference data in advance and uses it when calculating the flying height. In addition, a reference amplitude level value is substituted for the symbol V _ref shown in the equation (1), and an amplitude level value of the primary frequency component output by the FFT processing unit 180 is substituted for V _X. The
According to one embodiment of the present invention, the flying height calculation unit 120b acquires, for example, the amplitude level information of the first-order frequency component and the amplitude level information of the third-order harmonic component from the FFT processing unit 180, and the acquisition Based on the amplitude level information, the flying height of the magnetic head 160 is calculated using the following equation (2).

In the above equation (2), the symbols d and a are the same as the symbols d and a shown in the above-described equation (1), and thus description thereof is omitted. V ₁ shown in Equation (2) is the amplitude level of the first-order component, and V ₃ is the amplitude level of the third-order harmonic component.

Next, examples of the present invention will be described. 5 and 6 are diagrams for explaining an operation example of the magnetic memory device according to the first embodiment of the present invention. As shown in FIG. 5, the magnetic storage device 100 uses a magnetic head 160 to write predetermined pattern data (eg, 111111 or 111100) into a data area of the magnetic disk 170 at a predetermined frequency. For example, the frequency of the primary frequency component f ₁ written in the data area is set to about 100 MHz. In this case, the frequency of the third harmonic component f ₃ is about 300 MHz. In addition, 161 is a head slider and 162 is a suspension.

The magnetic storage device 100 includes a servo area shown in FIG. 6A and a data area in which the predetermined pattern data is written (one servo area and two data sectors in FIG. 6A). Read and play the data. Reference numeral 300 in FIG. 5 denotes the reproduced data (reproduced data). Then, the gate circuit 181 included in the FFT processing unit 180 replaces the reproduction data 300 in a predetermined time zone (x in FIG. 5) with other data to obtain new reproduction data 301. The reproduction data 300 in the predetermined time zone is data read from the servo area. That is, for example, as shown in FIG. 6B, the magnetic storage device 100 accurately “zero-pads” the data read from the servo area in time, thereby reproducing the reproduction data 300 in FIG. To the new reproduction data 301 shown in FIG. Then, the FFT processing unit 180 performs a fast Fourier transform operation on the new reproduction data 301, and the amplitude level of the primary frequency component f ₁ and the third harmonic component f ₃ as shown in FIG. Outputs the amplitude level.
The magnetic storage device 100 uses, for example, the above-described equation (2) based on the output amplitude level of the primary frequency component f _{1 and} the amplitude level of the third harmonic component f ₃ , and uses the magnetic head 160. Calculate the flying height.

  The number of sectors from which the magnetic storage device 100 reads data may be an arbitrary number (for example, N). That is, the magnetic storage device 100 of the present invention receives data (N pattern data written in the data area and data written in the N−1 servo area) from the magnetic disk 170 across N sectors. After reading and reproducing and replacing the data read from the servo area with other data, the N pattern data and the data after replacement of the data read from the N-1 servo areas are used. As the series of data, the flying height of the magnetic head 160 is calculated based on the series of data. Therefore, according to the magnetic storage device 100 of the present invention, even if the fluctuation period is longer than the time for which the magnetic head passes one sector length as shown in FIG. The fluctuation amount of the magnetic head can be obtained. Also, according to the magnetic storage device 100 of the present invention, the frequency resolution is greatly improved (frequency resolution is about 1 / N). For example, in the example of reading the pattern data written in two data areas and the data written in one servo area, the frequency resolution obtained according to the present invention is 36 kHz, and after 0 kHz (= DC), Since the vibration component intensities of 36, 72, 108, 144, and 180 kHz are obtained in order, the above-described vibrations of about 70 kHz to 90 kHz and vibrations of about 125 kHz to 150 kHz can be accurately distinguished.

  In addition, since the magnetic storage device 100 of the present invention replaces data read from the servo area with other data, the data written in the servo area during the Fourier transform operation processing has a large noise as in the prior art. Can be prevented. Therefore, according to the magnetic storage device 100 of the present invention, the flying height of the magnetic head 160 can be accurately calculated.

FIG. 7 is a diagram for explaining an operation example of the magnetic memory device according to the second embodiment of the present invention. In the second embodiment of the present invention, the magnetic storage device 100 applies a predetermined window function to a part (for example, both ends or all) of the data read and reproduced from the data area, and reads the data from the data area. The data reproduced and reproduced and the data (for example, zero data) obtained by replacing the data read and reproduced from the servo area are continuously changed. That is, a transition area 400 as shown in FIG. 7 is provided at the boundary between data read from the data area and reproduced and data obtained by replacing the data read from the servo area and reproduced. The magnetic storage device 100 uses the data multiplied by the predetermined window function and the data read from the servo area and reproduced as a series of data, and based on the series of data, the relative change in the flying height of the magnetic head, Alternatively, the absolute value of the flying height is calculated.
The hatched portion in FIG. 7 shows the result of multiplying the data read and reproduced from the data area by a Gaussian window function, which will be described later as a window function, at both ends of the data.
The predetermined window function h (n) is, for example, a continuous function having a range within a range from 0 to 1.
Further, the window function h (n) may be, for example, a triangular window function shown in the following formula (3).

  Further, the window function h (n) may be, for example, a Hanning window function shown in the following formula (4).

  Further, the window function h (n) may be, for example, a Hamming window function shown in the following formula (5).

  Further, the window function h (n) may be, for example, a Welch window function shown in the following formula (6).

  Further, the window function h (n) may be, for example, a Gaussian window function shown in the following formula (7).

  According to the magnetic storage device 100 of the present invention, since the data read from the data area and reproduced and the data in which the data read from the servo area and reproduced are replaced continuously, the magnetic storage apparatus It is possible to prevent the occurrence of noise due to the discontinuity of the data to be calculated in the Fourier transform calculation by the 100 FFT processing units 180.

  FIG. 8 is a diagram illustrating a result of multiplying both ends or all of the data read and reproduced from the data area by the respective window functions. Depending on the method of selecting the window function listed in FIG. 8 and the method of multiplying the window function (the method of multiplying both ends of the data or the method of multiplying all of them), there are combinations of how to provide a total of 10 transition regions. Even if the combination is used, the data read from the data area and reproduced and the data obtained by replacing the data read from the servo area and reproduced can be continuously changed.

As can be understood from the above, the features of the embodiment of the present invention are described as follows.
(Supplementary Note 1) Magnetic head in a magnetic storage device having a medium for storing data and a head for writing the data as a signal on the medium, and recording and reproducing the signal on the medium by magnetic means A method for measuring the amount of flying
Servo areas and data areas are alternately and repeatedly arranged on the medium surface, and predetermined pattern data is written in predetermined areas excluding the servo areas.
The magnetic head reads the data of the one or more servo areas and the area where two or more pattern data are written, and reproduces the first and second data, respectively.
Replacing the first data with other data to obtain third data,
At least two or more of the second data and the one or more of the replaced third data are used as a series of data, and a relative change in the flying height of the magnetic head based on the series of data, or A method for measuring a flying height of a magnetic head, comprising calculating an absolute value of the flying height.

(Supplementary Note 2) A Fourier transform operation is performed on the series of data to obtain a primary or multi-order frequency component, and the flying of the magnetic head is performed based on the obtained amplitude of the primary or multi-order frequency component. The method for measuring a flying height of a magnetic head according to appendix 1, wherein a relative change in the amount or an absolute value of the flying height is calculated.

(Supplementary note 3) At least a part of the reproduced second data is multiplied by a predetermined window function for continuously transitioning the second data and the obtained third data. The method for measuring a flying height of a magnetic head according to appendix 1 or appendix 2, wherein the second data multiplied by the predetermined window function and the third data are used as the series of data.

(Supplementary note 4) The method for measuring a flying height of a magnetic head according to supplementary note 3, wherein the predetermined window function is a continuous function having a value range within a range of 0 to 1.

ことを特徴とする付記４に記載の磁気ヘッドの浮上量計測方法。 (Supplementary Note 5) The predetermined window function is a triangular window function h (n) shown in the following expression (3).

The method of measuring a flying height of a magnetic head according to appendix 4, wherein:

ことを特徴とする付記４に記載の磁気ヘッドの浮上量計測方法。 (Supplementary Note 6) The predetermined window function is a Hanning window function h (n) shown in the following equation (4).

The method of measuring a flying height of a magnetic head according to appendix 4, wherein:

ことを特徴とする付記４に記載の磁気ヘッドの浮上量計測方法。 (Supplementary note 7) The predetermined window function is a Hamming window function h (n) shown in the following formula (5).

The method of measuring a flying height of a magnetic head according to appendix 4, wherein:

ことを特徴とする付記４に記載の磁気ヘッドの浮上量計測方法。 (Supplementary Note 8) The predetermined window function is a Welch window function h (n) shown in the following formula (6).

The method of measuring a flying height of a magnetic head according to appendix 4, wherein:

ことを特徴とする付記４に記載の磁気ヘッドの浮上量計測方法。 (Supplementary note 9) The predetermined window function is a Gaussian window function h (n) shown in the following equation (7).

The method of measuring a flying height of a magnetic head according to appendix 4, wherein:

(Supplementary Note 10) A magnetic storage device having a medium for storing data and a head for writing the data as a signal to the medium, and recording and reproducing the signal on the medium by magnetic means. ,
Servo areas and data areas are alternately and repeatedly arranged on the medium surface, and predetermined pattern data is written in predetermined areas excluding the servo areas.
The magnetic storage device includes a magnetic head flying height calculation means,
The magnetic head flying height calculation means obtains the first and second data respectively reproduced from the one or more servo areas and the area where two or more pattern data are written by the magnetic head,
Replacing the first data with other data to obtain third data,
At least two or more of the second data and the one or more of the replaced third data are used as a series of data, and a relative change in the flying height of the magnetic head based on the series of data, or A magnetic storage device that calculates an absolute value of a flying height.

(Appendix 11) A device for measuring the flying height of a magnetic head,
The servo area and data area are alternately and repeatedly arranged on the medium surface of the medium for storing data reproduced by the magnetic head, and the data written in the servo area and the predetermined area excluding the servo area are written. Receiving predetermined pattern data, obtaining first and second data respectively from the received data written in one or more servo areas and the two or more pattern data;
Replacing the first data with other data to obtain third data,
At least two or more of the second data and the one or more of the replaced third data are used as a series of data, and a relative change in the flying height of the magnetic head based on the series of data, or An apparatus for measuring a flying height of a magnetic head, characterized by calculating an absolute value of the flying height.

As described above, according to the present invention, it is possible to detect a continuous vibration (a vibration having a low frequency) whose wavelength is longer than one sector (one data area), and greatly improve the frequency resolution. It becomes possible. In addition, according to the present invention, data read from the servo area is replaced with other data, so that data written in the servo area during the Fourier transform processing is prevented from acting as a large noise. be able to. As a result, the flying height of the magnetic head can be accurately measured.
Further, according to the present invention, it is possible to prevent the occurrence of noise due to the discontinuity of the data to be calculated during the Fourier transform calculation.
With these effects, the flying height of the magnetic head can be further reduced, and as a result, the recording density of the magnetic recording apparatus can be increased.

It is a figure which shows an example of a structure of the magnetic storage apparatus of this invention. It is a figure which shows an example of a magnetic head. It is explanatory drawing (1) for demonstrating the relational expression of Wallace. It is explanatory drawing (2) for demonstrating the relational expression of Wallace. FIG. 4A is a diagram (1) illustrating an operation example of the magnetic memory device according to the first embodiment of the invention. FIG. 6B is a diagram (2) illustrating an operation example of the magnetic memory device according to the first embodiment of the invention. It is a figure explaining the operation example of the magnetic storage apparatus which concerns on Example 2 of this invention. It is a figure which shows the result of having multiplied each window function with respect to the both ends or all of the data read and reproduced | regenerated from the data area. It is a figure which shows the data area and servo area on a magnetic disc. It is a figure explaining the operation example of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Lower magnetic pole 3 Insulator layer 4 Thin film coil 5 Upper magnetic pole 6 Protective layer 7 Magnetic pole front-end | tip part 10 Thin film resistor 100 Magnetic storage device 110 Interface part 120 Control part 120a Read write process part 120b Levitation amount calculation part 120c Energization control part 120e Driver control unit 130 Motor driver unit 140 Spindle motor 150 Voice coil motor 160 Magnetic head 161 Head slider 162 Suspension 170 Magnetic disk 180 FFT processing unit 181 Gate circuit 200 Magnetic head flying height measuring device 300, 301 Playback data

Claims (5)

A magnetic storage device having a medium for storing data and a head for writing the data as a signal on the medium, and recording and reproducing the signal on the medium by magnetic means. Measuring method,
Servo areas and data areas are alternately and repeatedly arranged on the medium surface, and predetermined pattern data is written in predetermined areas excluding the servo areas.
The magnetic head reads the data of the one or more servo areas and the area where two or more pattern data are written, and reproduces the first and second data, respectively.
Replacing the first data with other data to obtain third data,
At least two or more of the second data and the one or more of the replaced third data are used as a series of data, and a relative change in the flying height of the magnetic head based on the series of data, or A method for measuring a flying height of a magnetic head, comprising calculating an absolute value of the flying height. A Fourier transform operation is performed on the series of data to obtain a first-order or multiple-order frequency component, and a relative change in the flying height of the magnetic head based on the obtained amplitude of the first-order or multiple-order frequency component 2. The method of measuring a flying height of a magnetic head according to claim 1, wherein an absolute value of the flying height is calculated. Multiplying at least part of the reproduced second data by a predetermined window function for continuously transitioning the second data and the obtained third data, the predetermined data The method for measuring a flying height of a magnetic head according to claim 1, wherein the second data multiplied by a window function and the third data are used as the series of data. A magnetic storage device having a medium for storing data and a head for writing the data to the medium as a signal, and recording and reproducing the signal on the medium by magnetic means,
Servo areas and data areas are alternately and repeatedly arranged on the medium surface, and predetermined pattern data is written in predetermined areas excluding the servo areas.
The magnetic storage device includes a magnetic head flying height calculation means,
The magnetic head flying height calculating means obtains the first and second data reproduced from the one or more servo areas and the area where two or more pattern data are written by the magnetic head, respectively. Replace the data of 1 with other data to obtain the third data,
At least two or more of the second data and the one or more of the replaced third data are used as a series of data, and a relative change in the flying height of the magnetic head based on the series of data, or A magnetic storage device that calculates an absolute value of a flying height. An apparatus for measuring the flying height of a magnetic head,
The servo area and data area are alternately and repeatedly arranged on the medium surface of the medium for storing data reproduced by the magnetic head, and the data written in the servo area and the predetermined area excluding the servo area are written. Receiving predetermined pattern data, obtaining first and second data respectively from the received data written in one or more servo areas and the two or more pattern data;
Replacing the first data with other data to obtain third data,
At least two or more of the second data and the one or more of the replaced third data are used as a series of data, and a relative change in the flying height of the magnetic head based on the series of data, or An apparatus for measuring a flying height of a magnetic head, characterized by calculating an absolute value of the flying height.

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