JPH08147607A - Magnetic disk apparatus - Google Patents

Abstract

PURPOSE: To restrain a drop in an information recording density and to set an error rate in an information read operation at a prescribed value or lower in a magnetic disk apparatus on which a dual head is mounted and which uses a rotary actuator. CONSTITUTION: In a magnetic disk apparatus, a dual head is provided with an MR head 1 exclusively used for data read operation and with an inductive head 2 mainly used for a data write operation, and a rotary actuator is used. In the magnetic disk apparatus, one ID part and one servo pattern are formed for one sector in a disk medium. Then, track pitches are made unequal, and ID parts are written in central parts of two radial positions which are positioned by the MR head when data is read and written. Consequently, even when servo signal regions and ID information regions are formed in sectors on the disk medium, it is possible to restrain a drop in an information recording density, and an error rate in an information read operation can be set at a prescribed value or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device having an improved dual head, track pitch and ID information and using a rotary type actuator. Here, the dual head refers to a magnetic head having two or more magnetic heads for reading or writing electromagnetic signals (data).

[0002]

2. Description of the Related Art A concentric magnetic recording area that is electromagnetically engraved on a magnetic disk medium by a magnetic head is called a magnetic track or simply a track. Such a track is formed by arranging a plurality of units of a recording area called a sector in a direction along the circumference. on the other hand,
A plurality of tracks are concentrically arranged in the radial direction of the disk medium to form one or a plurality of data zones which are information storage areas. The distance between adjacent track centers measured in the radial direction is called the track pitch. The magnetic head is mounted on a slider, and the slider moves on a disk medium from one track to another track by an actuator. This is called a seek operation.

A slider equipped with a magnetic head moves relatively on a track or a sector with a slight gap, so that the magnetic head electromagnetically reads a signal from a magnetic film on a disk medium. Or writing.

Normally, one ID section is provided in one sector in order to facilitate positioning of the magnetic head during seek operation, and the ID section stores information of the sector to which it belongs and other information. Has been done. One or more ID information may be provided in one track. Also, the ID of each sector
It is realistic to provide at least one ID information for one track, including information on where the part is located on the track.

A contact start stop (CSS) is a method of handling a magnetic head in which the magnetic head is positioned on the surface of the medium when starting or stopping the rotation of the disk medium, and in particular, the magnetic head is not retracted from the surface of the medium.

Here, as a conventional technique, Japanese Patent Laid-Open No. 4-13
7278, JP-A-6-28775, and
The one disclosed in JP-A-6-60573 will be mentioned. The techniques disclosed in these publications stabilize the reading of signals from the disk medium by setting a wide track pitch on the inner circumference side of the disk medium and a narrow track pitch on the outer circumference side, and stabilize the servo signal. The purpose is to ensure the above and to effectively use the disk medium. In the prior art of Japanese Examined Patent Publication No. 3-160675, two types of servo information are provided in one sector to improve the data read system and the servo system.

[0007] In these prior arts, no consideration is given to the ID information, the ID part or the error rate. Here, the error rate means a rate of erroneous reading when reading written data.

While the information storage capacity required of the magnetic disk device is increased, the device itself is required to be downsized. As the size of the device becomes smaller, the diameter of the disk medium used for the device must be smaller, and high density recording is required for the magnetic recording technology. Since a large amount of information is stored in a small disk medium, the magnetic reversal area (magnetization area) per unit area becomes small, and the signal based on the relative speed between the magnetization area and the gap of the magnetic head is reduced by the conventional electromagnetic induction effect. Reading technology is reaching its limits. In order to solve this, a magnetic reproducing technique using a magnetoresistive element has been studied. With this technology,
Since the MR element is used for the magnetic head (hereinafter referred to as "magnetoresistive head" or "MR head"), signal output independent of the relative speed between the magnetic medium and the magnetic head can be secured.
However, since the MR head is a read-only magnetic head, the conventional inductive head must be used together as a magnetic head for writing in an actual magnetic disk device.

[0009]

When performing high-density magnetic recording with a dual head, the write head and the read head mounted on the dual head have a gap in the geometrical arrangement of the respective gaps (hereinafter referred to as "offset"). Is a problem. That is, in the magnetic disk device in which the dual head is mounted on the rotary type actuator, the deterioration of the error rate of the ID portion due to the offset is inevitable when the ID information is read. The data is obtained by 1) the yaw angle (Yaw Angle, which will be described later) of the magnetic head due to the rotation of the rotary actuator, and 2) the radius difference from the spindle rotation center due to the geometric distance between the magnetoresistive head and the inductive head. This is because the head positioning radial position is different between reading and writing of data, and a steady offset is always generated when reading or writing the ID part.

Due to this offset, the magnetic disk device may fail to find the ID information during the seek operation. Or, because of this offset, the information of the most important ID part among the information stored in the sector may be unreadable. If the ID information can be read, the magnetic head can be accurately aligned with the subsequent data section, so that the error rate is improved in the data section than in the ID section.

Therefore, it is important to read the ID information without error, and for this purpose, the error rate of the area in which the ID information is stored must be suppressed to a predetermined value or less.
In particular, in a magnetic disk device that employs a so-called 1-sector 1-ID format, which has one type of ID information in one sector, the adverse effect of offset is significant.

[0012]

In the present invention, the following means are adopted. (1) The track pitch is set to be uneven at the inner and outer circumferences of the disk medium and dense at the center. (2) The write radial position of the ID part is set to be intermediate between the positioning radial position of the MR head when the MR head reads data and the positioning radial position of the MR head when the inductive head writes data. (3) The ID information is written after the area around the written portion of the ID portion is erased in advance. (4) The fluctuation amount in the actuator rotation angle corresponding to the track pitch is suppressed to 7% or less. (5) The error rate of the ID part is 1 × 10 ^-6 (minus 6
Power), the error rate of the data part is 1 × 10 ⁻⁸ (minus 8), and a dual head having a core width that satisfies a better numerical value is adopted. That is, in a head assembly in which the MR head and the inductive head have a nominal shift amount such that the difference between the radial positions at the central portion of the disk medium (disk) is 0, and the head actuator is always operated during CSS. A head assembly having a head yaw angle that receives a rotating force in the inner circumferential direction was used. (6) The disk medium is divided into n (n is a natural number) and divided into data zones to have an equal track pitch within the same zone and an unequal track pitch between the zones. In order to solve the above-mentioned problems, in order to fix the device, an area of a hole or a screw hole into which a fixing member from the outside penetrates from the device surface to the inside is a direction perpendicular to the magnetic disk surface, The structure is provided on the side wall of the assembly (HDA) within the range in which the outermost dimension between the inner surfaces of the three-dimensional (HDA) is extended in parallel.

[0013]

The operation will be described below in correspondence with the above. (1) Corresponding to the data recording density at each track position, the error rate of the ID part and the data part can be suppressed to be low against the influence of adjacent tracks and the influence of noise on the self-track. (2) It is possible to suppress the deterioration of the error rate when reading the ID part. (3) The influence of residual noise is eliminated and the error rate of the ID section is improved. (4) The unequal track pitch change does not adversely affect the seek movement distance variation, the position detection gain variation, or the position detection linearity variation that occurs when the head actuator seeks. (5) Under the most severe conditions, it is possible to set the error rate of the ID section, and it is possible to develop detailed specifications after reading the ID section. In addition, the inner CSS zone can be secured. Further, when starting the motor, it is possible to suppress the torque for starting the motor by overcoming the frictional force between the slider of the magnetic head and the medium disk. Also,
In addition to the effect of (2), the offset amount at the time of reading the ID portion is equal to the maximum value (PP value) of the radial offset amount.
It can be reduced to 1/2 x 1/2 = 1/4. (6) The processing load of the servo track processing time, seek system track processing time, and data system track processing time can be reduced.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

The magnetic disk device will be described with reference to FIGS. 9 and 10. The magnetic disk device includes a closed container 40 (FIG. 9), a disk 41 as a magnetic medium, a spindle motor 42 for supporting and rotating the disk 41, a head assembly having a magnetic head and a suspension arm for reading information from the disk 41. 43, a swing arm including a pivot shaft 44 for supporting the head assembly and swinging on the disc, a voice coil motor 45 for driving the swing arm, and a magnetic head for writing to and reading from the disc 41. And a printed wiring board 46 for electrical connection to a controller for controlling the operation of the spindle motor 42 and the voice coil motor 45. The disk 41, the spindle motor 42, the head assembly 43, a part of the printed wiring board 46, and the voice coil motor 45 are inside the container 40 and are sealed by the container 40.

The spindle motor 42 is an in-hub type motor in which a hub for fixing the disk 41 to the outer periphery and a rotor and a stator are arranged inside the hub.
It is installed on the base member constituting 0. Disc 4
Reference numeral 1 is an important component that determines the data storage capacity of the magnetic disk device. Usually, it is composed of, for example, one to several sheets depending on the capacity. In this embodiment, the disc 41 is alternately inserted into the hub of the spindle motor 42 with the disc spacer 48a (FIG. 10). Disc clamp 4
8b fixes the disc 41 to the spindle motor 42 by pressing the laminated body of the discs in the axial direction of the spindle motor 42.

There are several swing arms according to the number of disks 42, each of which is composed of a slider 49 having a magnetic head mounted thereon and a suspension arm 50.
The swing arm is rotatably fixed to the base member by a pivot shaft 44. The magnetic head is equipped with a dual head in which a thin film head for writing and a magnetoresistive head for reading are integrated and mounted on each of the sliders 49. In addition to this, an inductive head, a thin film head, an MIG head, or the like can be applied to the magnetic head.

The magnetic disk device of this embodiment employs a rotary actuator and a data surface servo, and has one ID information (ID part) and one servo information in one sector (hereinafter, "1ID / 1". "Servo method"). Further, in this embodiment, as the servo information, the servo pattern 7 is written at the position where the MR head 1 positions when writing the inductive head 2 (FIG. 3).

FIG. 1 shows an example of setting the unequal track pitch of the present invention. The track pitch is set linearly at the inner and outer peripheries of the disk medium, which is the information storage area, and narrowed at the center of the information storage area of the disk medium.

As a result, the error rate of the ID portion and the data portion of the sector in each track at the position in the radial direction of the disc on the disc medium (hereinafter referred to as "radial position") is the error rate of the ID portion. 1 x 10 ^-6
(Minus 6), the error rate of the data part is 1 × 10
^-8 (minus 8th power), a better number (lower number).

In this embodiment, in the dual head,
The distance between the center of each gap of the MR head 1 and the inductive head 2 using the magnetoresistive effect element and the rotation axis of the spindle (radius difference on the disk medium, hereinafter referred to as “radius difference”) is It is 30 conditions of 8. That is, the dual head MR head 1 and the inductive head 2 are located at the center of the information storage area of the disk medium.
Has a radius difference of 0. The track pitch was narrowed at this location, and the track pitch was set wide in the data area (inner circumference or outer circumference) where the radius difference increased. In this way, the track pitch is widened where the radius difference is large, that is, the area where the error rate of the ID part is deteriorated, and the track pitch is narrowed where the radius difference is small to improve the error rate of the ID part. Are doing.

FIG. 2 shows the structure of a dual head. In the dual head of this embodiment, a magnetoresistive head 1 (MR head 1) dedicated to reading data is provided at the tip of one head core (not shown), and a gap distance b which is a constant distance from the magnetoresistive head 1. The magnetic head is provided with the inductive head 2 at a different position.

In the rotary actuator, the head yaw angle (Yaw Ang) is calculated as a function of the radius (r) on the disk.
le) θ = θ (r) exists. Therefore, in the rotary actuator, the gap distance b is 0, or θ =
When the value is other than 0, the radial position of the head at the time of Write of information and at the time of Read is displaced from the disk medium or the spindle axis.

FIG. 3 shows the data Write in this embodiment.
8 shows the radial position of the dual head and the radial positions of the servo pattern, the ID part, and the data part at the time or data Read. In the figure, On Trac during Write
k is the center line of the servo pattern and is the ID part On Tra
ck is the center line of the ID part, and it is On T
Rack means the center line of the data part.

In the dual head (FIG. 2), the radial position where the MR head 1 positions when the MR head 1 is read and the inductive head are set in any track depending on the gap distance b (3) and the head yaw angle θ (4). Is the radial position where the MR head 1 positions during Write,
A radius difference δ of δ = bsinθ occurs (FIG. 3).

Further, in this embodiment, as the servo information, the one-servo system is used in which the servo pattern 7 is written at the position where the MR head 1 positions the inductive head during the Write. In order to reliably achieve the performance of the magnetic disk device, in particular, high density recording, each sector is provided with an ID section, and after reading it, the information of that sector is acquired.
Alternatively, it is necessary to write information in that sector. In other words, it is necessary to read the ID portion with the MR head 1 in either reading or writing of data.

In the present embodiment, the write radial position of the ID portion is intermediate between the MR head positioning radial position when the MR head reads data and the MR head positioning radial position when the inductive head writes data. And As a result, the offset amount from the positioning radial position of the MR head is written at a position of 1/2 of δ so that the offset amount is minimized, so that the offset amount can be reduced from δ to δ / 2. Here, δ means a radius difference when measured at the center of each gap of the MR head and the inductive head by θ at an arbitrary track position and the gap distance b.

Compared with the prior art having an ID section and servo information for each dual head, the fact that the present invention can reduce the offset amount to the above-mentioned offset amount has an excellent effect in terms of an increase in information storage capacity. As described above, the data section 9 is written in the positioning position when the data read of the MR head 1 is performed, and the ID section 8 is written in the data section 9
More δ / 2 is written at a distant position (Fig. 3).

FIG. 4 illustrates the case where there is residual noise in the ID section. If there is residual noise 11 in the ID part, I
When reading the D portion 8 with the MR head 1, in the present embodiment, M
At the position where the R head 1 reads the data portion 9, the residual noise 11 of the ID portion is read, and the error rate of the ID portion is reduced. Therefore, by writing the ID section 8 after erasing the ID section, the influence of the residual noise 11 in the ID section can be eliminated. Erase is performed by the inductive head 2 having a wider core width than the MR head 1.

[0030]

[Table 1]

Table 1 shows representative values of the error rates of the data part and the ID part in the case of unequal track pitch shown in FIG. When the track pitch is equal, the error rate of the data part is 1 ×
Although 10 ^-9 (minus 9th power) can be secured, the ID part has an inner circumference of 2.3 x 10 ^-6 (minus 6th power) and specifications 1 x 10
I cannot satisfy ^-6 (minus 6). On the other hand, by setting the unequal track pitches, it is possible to secure an ID part error rate of 1 × 10 ⁻⁶ (minus 6th power) and a data part error rate of 1 × 10 ⁻⁹ (minus 9th power).

In FIG. 5, the unequal track pitch is set so that the variation of the rotation angle of the carriage corresponding to the change of the track pitch is 7% or less at the unequal track pitch. Compared with FIG. 1, in order to suppress the change in track pitch, a combination of three straight lines is used.
Originally, the change in the track pitch does not need to be a straight line, and may be an arbitrary curve. In this embodiment, a straight line combination is used because of the simplicity of data processing. If it is set to 7% or less, in the electronic circuit of the magnetic disk device, signal processing from the servo track, signal processing from the track at the time of seek,
The signal processing from the track when acquiring data can be achieved with a simple circuit.

FIG. 6 illustrates the yaw angles θ1, θ2 and other quantities of the magnetic head in this embodiment, and the geometrical arrangement in which the actuator receives a force in the inner circumferential direction of the disk disk during CSS. It was done. An actuator (not shown) is supported by a carriage bearing 21 and swings about a carriage rotation center 13. A dual head (not shown) is attached to the actuator at a distance of 18. The actuator is
The disk 19 oscillates between the innermost zone radial position 16 and the outermost zone radial position 17, and the head yaw angle θ1
The yaw angle changes between (24) and θ2 (25).

In this embodiment, the spindle rotation center 12, the carriage rotation center 13, the rotation center of the magnetic head and the carriage, and the distance 18 are adjusted so that the carriage during CSS is
The yaw angle is set so that it always faces inward by the frictional force between the magnetic head and the disk. With this setting, it is possible to guarantee that the head always performs CSS on the inner circumference.

7 and 8 show an embodiment of a dual head in which the nominal shift amount a (28) is set between the MR head 1 and the inductive head 2. When the nominal shift amount a is 0 (FIG. 2), the gap distance b between the MR head 1 and the inductive head 2 and the radial difference δ caused by the yaw angle θ of the head are calculated with respect to the radial direction of the disk medium. This is indicated by 29 in FIG. Here, the yaw angle of the magnetic head is almost 0 at the inner circumference of the disk.
It was set so that

The yaw angle is 0 at the radial center of the disc.
If the nominal shift amount a is set to 0 (FIG. 2), the offset amount of the ID portion is δ / 2 in the disk medium format of the present embodiment (FIG. 3), and δ / 2max. Is about 1 μm (30 in FIG. 8). Therefore, if the nominal shift amount a is further adjusted in the central part of the data area, the offset amount δ / 2 of the ID part is 0.5 μm.
It can be reduced to a certain degree. Therefore, the deterioration of the error rate of the ID part can be further improved.

[0037]

By applying the present invention, it is possible to suppress the decrease in the format efficiency of the ID section and to improve the error rate of the ID section due to the unequal track pitch.

The write radial position of the ID portion is the radial position of the MR head when the MR head reads data, and
By writing in the center of the positioning radial position of the MR head when the inductive head writes data, the offset amount at the time of reading the ID portion by the MR head can be reduced to half. Therefore, the error rate of the ID part can be improved.

By erasing the ID section before writing the ID section, the error rate of the ID section could be improved.

The error rate of the ID part can be set to 1 × 10 ^-6 (minus 6) or less, and the error rate of the data part is 1 ×.
Since it can be 10 ⁻⁸ (minus 8) or less, the basic conditions for achieving the various functions of the magnetic disk device can be satisfied.

By suppressing the fluctuation amount of the actuator rotation angle corresponding to the track pitch to 7% or less, the adverse effect of the signal output on the servo circuit could be eliminated.

By making the core width of the inductive head larger than the core width of the MR head and adopting an unequal track pitch, the error rate of the ID part and the data part could be kept below a predetermined value.

The radial offset amount of the R / W gap is halved by setting the nominal shift amount of the R / W gap so that the radial offset amount of the R / W gap becomes 0 at the center of the data area. Therefore, it is possible to further reduce the offset amount of the ID part by half.

By dividing the information storage area of the disk medium into zones, it is possible to reduce the processing load on the electronic circuit of the data system or the seek system.

[Brief description of drawings]

FIG. 1 is a diagram showing a track density at a radial position of a disk on a disk medium.

FIG. 2 is an explanatory diagram showing a positional relationship between magnetic gaps of a dual head.

FIG. 3 is a diagram showing a format of a track on a medium disc which is an embodiment of the present invention.

FIG. 4 is a diagram for explaining the influence of residual noise in the ID section.

FIG. 5 is a diagram showing track densities at a radial position of a disk on a disk medium when the track pitch is set so that a change in the carriage rotation angle is 7% or less.

FIG. 6 is a diagram for explaining a yaw angle of a magnetic head.

FIG. 7 is an explanatory diagram of a positional relationship of each gap when a nominal shift amount a is set for the inductive head 2 and the MR head 1 in the dual head.

FIG. 8 is a diagram for explaining an R / W offset amount of the entire device when a dual head is used.

FIG. 9 is a plan view showing an embodiment of a magnetic disk device to which the present invention is applied.

10 is a side view of the magnetic disk device of FIG. 9. FIG.

[Explanation of symbols]

1 ... MR head (magneto-resistive head) used as a read-only head in a dual head, 2 ... Inductive head mainly used for writing in a dual head, 3 ... Between a gap between a dual head MR head and an inductive head Distance b, 4 ... Head yaw angle θ, 5
... Radial difference δ when measured at the center of each gap between the MR head and the inductive head, depending on θ and the gap distance b at an arbitrary track position, 6 ... Radial difference from the center of the servo pattern portion to the center of the ID portion measured δ / 2, 7
... Servo pattern part positioned by the dual head MR head during data writing, 8 ... ID part, 9 ... Data part, 10 ... Track pitch Tp, 11 ... ID part residual noise, 12 ... Spindle rotation center, 13 ... Carriage rotation Center, 14 ... Information storage zone innermost head position, 15 ... Information storage zone outermost head position, 16
... radially innermost position of information storage zone, 17 ... radially outermost position of information storage zone, 18 ... distance between magnetic head and carriage rotation center, 19 ... disk medium disk, 20 ... clamp, 21 ... carriage bearing, 22 ... 14, the tangential force applied to the slider during CSS, 2
The tangential force applied to the slider during CSS in 3 ... 15, the head yaw angle θ1, 25 in 24 ... 14
The head yaw angle θ2 at 15, ... 26, CSS at 14,
Force in the carriage rotation direction applied to the slider at the time of 2
7 ... 15, force in the carriage rotation direction applied to the slider during CSS, 28 ... Nominal shift amount a of dual head MR head and inductive head, 29 ... Nominal shift amount a = 0, head yaw near the inner circumference of the disk When the angle θ = 0, the radial difference δ, 30 between the inductive head and the MR head with respect to the head position in the radial direction on the disc disk, the nominal shift amount a = 0, and the yaw angle θ = 0 of the head near the center of the disc. At a radial position where the yaw angle θ = 0 in the radial difference δ, 31 ... 30 with respect to the head position in the radial direction on the disk disc.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Tsuyoshi 2880 Kozu, Odawara, Kanagawa Stock Company Hitachi Storage Systems Division (72) Inventor Tetsuji Kameoka 2880 Kozu, Odawara, Kanagawa Hitachi Storage Co., Ltd. System Division (72) Inventor Haruhiko Hosokawa 2880 Kozu, Odawara-shi, Kanagawa Hitachi Storage Systems Division (72) Inventor Takashi Yamaguchi 2880 Kozu, Odawara, Kanagawa Hitachi Storage Systems Division

Claims (4)

[Claims] 1. A magnetic disk medium having, in addition to servo information for controlling the rotation of the magnetic disk medium, at least one ID information for each unit of information storage, and reading or reading information from the magnetic disk medium. A dual magnetic head for writing, a slider having two gaps for magnetic recording or magnetic reproduction on a slider, a spindle motor for supporting and rotating the magnetic disk medium, the magnetic head, A head assembly having a slider and a supporting member for supporting the slider; a swing arm including a pivot shaft that supports the head assembly and swings on the magnetic disk medium; and a voice coil motor that drives the swing arm. Writing and reading information to and from the magnetic disk medium Electronic circuit for the gas head, and a magnetic disk apparatus having a controller for controlling the operation of the spindle motor and the voice coil motor. 2. The magnetic disk drive according to claim 1, wherein the dual head has a read-only MR head and an inductive head exclusively for writing, and the core width of the MR head is smaller than the core width of the inductive head. . 3. The magnetic disk drive according to claim 2, wherein, in the dual head, the gap center of the MR head and the gap center of the inductive head are displaced in the direction of the gaps. 4. A magnetic disk medium having sectors on the magnetic disk medium, having one ID part and one type of servo pattern in one sector, and reading or writing information from the magnetic disk medium. A magnetic head, a dual head having a head for reading information and a head for writing information on one slider; a spindle motor for supporting and rotating the magnetic disk medium; A head assembly having a head, the slider, and a support member for supporting the slider, a swing arm including a pivot shaft that supports the head assembly and swings on the magnetic disk medium, and a voice coil that drives the swing arm. A motor is used to write and read information to and from the magnetic disk medium. Electronic circuit for the head, and a magnetic disk apparatus having a controller for controlling the operation of the spindle motor and the voice coil motor. A device on the opposite side of the carriage from a center line that passes through the center of rotation of the recording medium parallel to the short side of the rectangle of the widest surface of the rectangular parallelepiped that forms the hole or screw hole in the outermost shape of the device. The magnetic disk device according to claim 1, wherein at least one portion is provided between the recording medium and the outermost shape of the apparatus, which is an area up to the outermost shape.