JPH09312074A - Recording medium for data recording/reproducing device and data recording/reproducing device provided therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the execution of accurate positioning control even though a head is positioned anywhere on a recording medium by forming the burst data structure with the use of burst signals of each group. SOLUTION: A plurality of servo regions are radially arranged from a center of the recording medium. On these servo regions, the burst signals A, B respectively having the same width as the track pitch while making the center positions of each track to their borders are alternately recorded, and also the burst signals C, D having the same width as the track pitch while making each track border to their borders are alternately recorded. Further, the burst signals E, F having a half width of the track pitch while making the positions ±1/4 track shifted from the center positions of each track to the borders are alternately recorded. Then, the head is always maintained in either one of the ranges, wherein the difference of output levels of the signals A and B against the head position becomes linear, the difference of output levels of the signals C and D becomes linear, or the difference of output levels of signals E and F becomes linear.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium for a data recording / reproducing apparatus in which a plurality of sets of burst data used for controlling the positioning of a head for recording / reproducing data is recorded, and data provided with the recording medium. The present invention relates to a recording / reproducing device.

[0002]

2. Description of the Related Art In a data recording / reproducing apparatus typified by a magnetic disk apparatus in which data is recorded / reproduced by a head, data is recorded at a specified position on the recording medium (disk) based on servo data recorded on the recording medium. It is general to apply a so-called sector servo type positioning control for seeking and positioning the head. Hereinafter, the positioning control of the sector servo system will be described using a magnetic disk device as an example.

First, in the servo data, in addition to sector data indicating a sector number (servo sector number) and cylinder data indicating a cylinder number (cylinder address), position information (positional error in the cylinder indicated by the cylinder data) is converted into a waveform. Burst data (burst pattern) that is data for indicating the amplitude is included. This burst data is composed of four burst signals A, B, C and D, and a combination of burst signals A and B among them,
Head positioning control is performed by the combination of C and D.

The recording width of each burst signal A, B, C, D is one track pitch width. As shown in FIG. 9, the burst signals A and B are a set of a pair of burst signals having different phases, which are alternately arranged at a track width with the center of the track as a boundary. The burst signals C and D are tracks. 1 on the border
It is a set of a pair of burst signals having different phases which are alternately arranged in the track width.

The servo processing system of the magnetic disk drive moves the head to the target cylinder based on the cylinder data in the servo data reproduced by the head and the burst data consisting of the burst signals A, B, C and D.
Finally, it is common to position the head at the center of the target cylinder (center of the track). The details of the positioning of the head are as follows.

First, the peak values of the burst signals A, B, C and D reproduced by the head are sampled and held.
If the burst outputs that are the sample and hold values are A, B, C, and D, respectively, the difference A- between the head position (center position of the head) on the disk and the burst outputs A and B
The relationship between B and the difference CD between C and D is as shown in FIG.

As is apparent from FIG. 10, when the head is located within a range of ± 1/4 track from the center of the track (for example, a position X2 deviated by -1/4 track from the center X3 of the track n). From the center X3 of track n +
(If it is within the range of position X4 that is displaced by 1/4 track)
In addition, since the burst output difference A−B has a linear relationship with the head position (linear relationship) and A + B is constant, (A−B) / (A + B) is also linear with respect to the head position. (However, ± 1 / from the center of the track
(Excluding the vicinity of the position that is offset by 4 tracks). Therefore,
Burst outputs A and B (outputs of burst signals A and B) are used for positioning control within this range. Especially when the head is located at the center of the track, burst output A, B
(The information amounts of the burst signals A and B) are equal.

On the other hand, when the head is displaced from the center of the track by ± 1/4 track or more, that is, within the range of ± 1/4 track from the track boundary (for example, track n, n + 1 boundary X5 to -1
In the case where the position X4 deviated by / 4 tracks and the position X6 deviated by +1/4 tracks from the boundary X5 between the tracks n and n + 1) are present, one of the burst outputs A and B is irrelevant to the head position. Is always 0. In such a range, correct position information cannot be obtained even if the burst outputs A and B are used. On the other hand, the difference C−D between the burst outputs C and D has a linear relationship with the head position in this range, and C + D is constant (C−D) /
(C + D) also has a linear relationship with the head position (except for the vicinity of the position displaced by ± 1/4 track). Therefore, the burst outputs C and D (output of the burst signals C and D) are used for the positioning control within this range.

As described above, in the data recording / reproducing apparatus to which the burst data having the structure shown in FIG. 9 is applied, when the head is located within the range of ± 1/4 track from the center of the track, the burst signals A and B are generated. Is used, and burst signals C and D are used when the position is out of the range.

Now, in order to obtain the head position information (the position displacement amount of the head from the track center, that is, the position error) from the burst output (output of the burst signal), {(A−B) / (A + B)} * G: The calculation formula (1) is used. Here, G is a correction coefficient determined by the width of the head, the track width (track pitch), etc. The servo processing system of the magnetic disk device has the above (1).
The position information of the head calculated according to the formula is fed back to seek and position the head to the target cylinder. Here, when positioning at the center of the target cylinder, control is performed so that {(A−B) / (A + B)} * G = 0.

When the burst signals C and D are used, A + B is C + D and AB is C- in the equation (1).
It may be replaced with D respectively. However, since the position information obtained in this case indicates the amount of head displacement from the track boundary, to obtain the amount of head displacement from the track center, add 1/2 track width (corresponding value). Or you need to subtract.

[0012]

However, as described above, there is a typical magnetic disk device which controls the positioning of the head for recording and reproducing data based on a plurality of sets of burst signals recorded on the disk. The conventional data recording / reproducing apparatus has the following problems.

First, as is clear from FIG. 10, the burst signal output (difference) is not linear (non-linear range) depending on the head position (for example, range β).
In that range (a region near the position shifted by ± 1/4 track from the track center) β, the reliability as burst data is low, and this non-linear range β is the burst signal A, B and the burst. The signals C and D overlap each other. Therefore, when the head is within the non-linear range β, the set of burst signals A and B and the burst signals C and D are used.
Correct position information cannot be obtained by using any of the above sets, and accurate positioning control cannot be performed.

As a reproducing / recording head, FIG.
A reproducing / recording separation type head 20 as shown in FIG. 1, namely, a data recording head (write head) 21 and an MR head (Magnet
When a read / write separated type head 20 having a data reproducing head (read head) 22 represented by o-Resistive) is used, the read head 2 is used at the time of writing when the write head 21 needs to be positioned at the track center TC.
2 does not read the track center TC, but reads the burst data at a position (off-track position) slightly deviated from the track center TC. In such a case, the normal head positioning control as shown in the prior art cannot read the correct burst data, and thus the accurate positioning control cannot be performed.

The present invention has been made in consideration of the above circumstances, and its object is to provide first and second burst signals (A, B).
And a set of third and fourth burst signals (C, D),
A set of fifth and sixth burst signals (E, F) alternately arranged with a width of ½ of the track pitch is added at a position deviating from the center position of each track by ± 1/4 track. A burst data structure is to provide a recording medium for a magnetic disk device and a magnetic disk device that can accurately perform positioning control regardless of the position of the head on the recording medium.

[0016]

A recording medium for a data recording / reproducing apparatus according to the present invention has a structure in which a plurality of servo areas used for head positioning and the like are radially arranged from the center of each recording medium across each track. In the servo area, first and second burst signals (burst signals A and B) having the same width as the track pitch are alternately recorded with the center position of each track as a boundary, and each track boundary is recorded. The third and fourth burst signals (burst signals C and D) having the same width as the track pitch are alternately recorded at the boundary of, and further at a position deviated by ± 1/4 track from the center position of each track, Fifth and sixth burst signals (burst signals E and F) having a width of 1/2 the track pitch are recorded alternately, and the difference between the output levels of the burst signals A and B with respect to the head position is linear. , The range in which the difference between the output levels of the burst signals C and D with respect to the head position is linear, and the range in which the difference between the output levels of the burst signals E and F with respect to the head position is linear. It is characterized by doing so.

A data recording / reproducing apparatus of the present invention comprises a recording medium having the burst data structure described above, a set of burst signals A and B from the burst signals A to F read by the head from the recording medium, and a burst. One of the pair of signals C and D and the pair of burst signals E and F is selectively used to calculate the position shift amount of the head from the track center, and the head shift amount is calculated based on the position shift amount. And a head positioning control means for positioning to the target cylinder. When the absolute value of the difference between the output levels of the burst signals A and B is within a predetermined threshold, the head positioning control means selects the set of burst signals by selecting the set of burst signals A and B. , If the absolute value of the difference between the output levels of the burst signals C and D is within the above threshold, the set of the burst signals C and D is selected, and if neither is the case, the set of the burst signals E and F is selected. Apply the logic to do so.

In the above structure, a burst data structure in which a set of burst signals E and F is newly added to a set of burst signals A and B and a set of burst signals C and D which have been used conventionally is applied. And burst signals A and B
Output level difference (difference between burst outputs A and B A-
B) and the difference between the output levels of the burst signals C and D (the difference C-D between the burst outputs C and D) are both in the center of the range that is non-linear with respect to the head position (as is clear from FIG. 10). , The burst signals E and F are alternately recorded with a width of ½ of the track pitch.

As a result, E- (with respect to the head position)
The F characteristic is A (it is difficult to obtain a correct head positional deviation amount only with the set of burst outputs A and B and the set of C and D).
-B and CD characteristics are linear in a range where both are non-linear with respect to the head position. Therefore, by using the burst outputs E and F in this range, it is possible to obtain the correct head positional deviation amount, and it is possible to realize accurate head positioning control. Here, the ranges in which the AB and CD characteristics are both non-linear with respect to the head position are AB and C.
It can be regarded as a common range in which the values of −D both exceed the threshold value.

In addition, in the head range in which the E-F characteristic is linear, in other words, in the head range in which the A-B and C-D characteristics are both non-linear with respect to the head position, a set of burst outputs A and B or a burst output is generated. It is also possible to obtain position information indicating the amount of positional deviation of the head from the set of outputs C and D, and correct the position information information by the burst outputs E and F.
In this correction, the AB characteristic in the head range in which the E-F characteristic is linear is supplemented by the E-F characteristic, or the CD characteristic in the head range in which the E-F characteristic is linear is determined by the E-characteristic. It is realized by supplementing with the -F characteristic.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a magnetic disk drive will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a magnetic disk drive according to one embodiment of the present invention.

In FIG. 1, 1 is a disk (magnetic disk) which is a medium on which data is recorded, and 2 is a head used for writing data to the disk 1 (data recording) and reading data from the disk 1 (data reproduction). (Magnetic head). The head 2 is provided corresponding to each data surface of the disk 1.

A large number of concentric tracks are formed on both sides of the disk 1 as shown in FIG. 2, and each track is divided into a plurality of sectors (servo sectors) 100.
Each servo sector 100 has a servo area 110 in which servo data is recorded and a user area 120 in which data (user data) is recorded (constituting a plurality of data sectors).
Consists of The servo areas 110 are arranged radially on the disk from the center across each track.

The servo area 110, as shown in FIG.
AGC stabilization area (amplitude AGC area) 11 in which data of a constant frequency is recorded in order to stabilize the signal amplitude
1. Sector data area 112 in which sector data indicating erase and sector number (servo sector number) is recorded, cylinder data area 113 in which cylinder data indicating cylinder number (cylinder address) is recorded, and position information (cylinder indicated by cylinder data). It has a well-known area, such as a burst area 114 in which burst data (burst pattern), which is data for indicating the position error) in the waveform amplitude, is recorded. However, the burst area 114 includes four conventionally known burst signals (position error signals).
In addition to the recording areas a, b, c, d of A, B, C, D,
It comprises areas e and f for newly recording burst signals E and F. The burst data is composed of these six burst signals A, B, C, D, E and F. Of these, the combination of burst signals A and B, the combination of C and D, and the combination of E and F are used. Head positioning control is performed.

The recording width of the burst signals A, B, C and D is the same as the track pitch as in the conventional case, and the recording width of the new burst signals E and F is 1/2 the track pitch.

The burst signals A, B, C, D, E, F
FIG. 4 shows the mutual positional relationship on the disk 1. FIG.
As is clear from the above, the burst signals A and B are a pair of burst signals having different phases, which are alternately arranged at a track width with the track center (TC) as a boundary, and the burst signals C and D are tracks. It is a set of a pair of burst signals having different phases, which are alternately arranged with one track width at the boundary.
Further, the burst signals E and F are ± 1/4 track width (width of 1/4 of track pitch) from the track center (TC).
± 1 from the track boundary at the offset position
4 With the track width offset position, 1 / the track pitch
It is a set of a pair of burst signals having different phases and alternately arranged with a width of 2.

Referring again to FIG. 1, the disk 1 is rotated at high speed by the spindle motor (SPM) 3. The head 2 is attached to a head moving mechanism called a carriage 4, and moves in the radial direction of the disk 1 by the movement of the carriage 4. The carriage 4 is driven by a voice coil motor (VCM) 5.

The spindle motor (SPM) 3 and the voice coil motor (VCM) 5 are connected to the motor driver 6. The motor driver 6 is a spindle motor 3
The motor 3 is driven by supplying a control current to the voice coil motor 5, and the motor 5 is driven by supplying a control current to the voice coil motor 5. The value of the control current (control amount) is determined by calculation processing of the CPU (microprocessor) 10, and is given, for example, as a digital value.

Each head 2 is connected to a head IC 7 mounted on a flexible printed wiring board (FPC), for example. The head IC 7 controls switching of the head 2, input / output of a read / write signal with the head 2, and the like, and includes a head amplifier 71 that amplifies an analog output read by the head 2.

The head IC 7 is connected to a read / write IC (read / write circuit) 8. The read / write IC 8 roughly has an encode / decode function for processing user data and a signal processing function for processing servo data.

The read / write IC 8 inputs the analog output (the read signal of the head 2) read from the disk 1 by the head 2 and amplified by the head amplifier 71 in the head IC 7, and a signal necessary for the data reproducing operation. Processing, for example, signal processing for converting analog output to NRZ data and transferring it to the disk controller (HDC) 14 is performed by the decoding function. Read / write IC8
Is a signal processing required for the data recording operation, for example, HDC1
The data (eg, 2-7, 1) that modulates the NRZ data (write data) sent from
-7 modulated data) and sends it to the head IC 7 by an encode function.

The read / write IC 8 also executes, by a signal processing function, reproduction processing of servo data necessary for servo processing such as head positioning control, in addition to the normal recording / reproduction processing of user data. That is, read / write I
C8 is the servo area 110 read by the head 2.
And outputs a data pulse including cylinder data to the servo processing circuit 9. In addition, the read / write IC 8 uses the burst signals A (in the servo data)
The peak values of to F are sampled and held and output to the servo processing circuit 9.

The servo processing circuit 9 is a read / write IC.
In response to the data pulse and the burst data from the control unit 8, signal processing necessary for servo processing is executed. That is, the servo processing circuit 9 has a decoding function for extracting and decoding cylinder data (cylinder number) and the like from the data pulse from the read / write IC 8, and a timing generation function such as a write gate. Also, the servo processing circuit 9 has a read / write I
It also has an A / D conversion function of A / D (analog / digital) converting the sample hold result of the peak value of each burst signal A to F from C8 and outputting to the CPU 10. The servo processing circuit 9 is configured using, for example, a gate array (GA).

The CPU 10 is, for example, a one-chip microprocessor. The CPU 10 controls each unit in the magnetic disk device according to a control program (firmware) stored in the ROM 11.

The CPU 10 constitutes a servo processing system (head positioning control mechanism) for executing head positioning control together with the servo processing circuit 9, and converts the cylinder data extracted by the servo processing circuit 9 and the servo processing circuit 9 concerned. The A / D conversion value (hereinafter, referred to as burst outputs A to F) corresponding to the sample and hold result of the peak values of the burst signals A to F thus read is read from the servo processing circuit 9, and the motor driver 6 is read according to the read data. Head control is performed to move the head 2 to the target cylinder and position it at the center of the target cylinder (track center) by driving and controlling the voice coil motor 5 via the head. Here, for the positioning control to the center of the target cylinder, position information (position is calculated based on any one of a set of burst outputs A and B, a set of C and D, and a set of E and F). Error) is used. Which set of burst outputs is used is determined as follows. First, in the head range where the difference AB between the burst outputs A and B is linear with respect to the head position, a set of burst outputs A and B is used,
The difference C-D between the burst outputs C and D is linear with respect to the head position. In the head range, a set of the burst outputs C and D is used, and the difference E-F between the burst outputs E and F is linear with respect to the head position. In a wide head range, a set of burst outputs E and F is used. Whether it is a linear head range,
Absolute value of burst output difference is a predetermined threshold value Vth
It can be determined by whether or not the following.

In addition to the head positioning control, the CPU 10 also controls the read / write data transfer by controlling the HDC 14. The CPU 10 is a rewritable ROM (Read Only Memory) 11 as a non-volatile memory that stores a control program (firmware) for controlling each unit in the magnetic disk device, a work area of the CPU 11 and the like. RAM (Random Access Memory) 12 as a volatile memory and an EEPROM (Electrical) as a rewritable nonvolatile memory
ly Erasable and Programmable Read Only Memory) 1
3 is connected. This EEPROM 13 has parameters for controlling the magnetic disk device (each servo sector 1
The number of data sectors for each 00, the offset between the servo area 110 in the corresponding servo sector 100 and the first data sector,
It is used to store a table of parameters such as data sector intervals). In addition, the disk 1 is a CDR (Constant D
When the (ensity recording) method is applied, that is, when the disk 1 is divided into a plurality of zones and the number of constituent data sectors is different for each zone, the above parameters are Are stored for each servo sector for each zone.

A disk controller (HDC) 14 is also connected to the CPU 10. The HDC 14 controls communication of commands and data with the host device, and also controls data communication with the read / write IC 8 (via the disk 1). In this HDC 14,
Read / write data is stored in a cache manner,
For example, a buffer memory (buffer RAM) 15 composed of a RAM or the like and a host interface 16 are connected. The host interface 16 serves as an interface between the HDC 14 and the host device.
Reference numeral 4 communicates commands and data with the host device via the host interface 16.

Next, the head positioning control operation in the configuration of FIG. 1 will be described with reference to the flowchart of FIG. When a read / write command or a seek command is given from the host device via the host interface 16, the HDC 14 generates a target cylinder number indicating a target cylinder to position the head 2 from the logical address included in the command. And outputs it to the CPU 10.

In response to this, the CPU 10 moves (seeks) the head 2 to the target cylinder and performs seek / positioning control for positioning at the center of the target cylinder (track center) as follows.

First, during seek / positioning control,
The information recorded on the disc 1 is read by the head 2. The read signal (analog output) which is the read output of the head 2 is sent to the head IC 7 (the head amplifier 7 in the head IC 7).
It is amplified in 1) and supplied to the read / write IC 8.

In the read / write IC 8, the head IC
A data pulse is extracted from the read signal from the head 2 amplified in 7 by pulse peak detection. In the read / write IC 8, the peak value of each burst signal A to F (in the servo data) included in the read signal from the head 2 is sampled and held.

The data pulse extracted by the read / write IC 8 and the peak value of the burst signals A to F sampled and held by the read / write IC 8 (sample and hold value of the burst signals A to F) are sent to the servo processing circuit 9. To be

The servo processing circuit 9 is a read / write IC.
Data pulses from 8 are input and decoded, and cylinder data and the like (servo data thereof) are extracted and decoded. If the cylinder data etc. (servo data thereof) can be normally decoded, the servo processing circuit 9 sends the decoded cylinder data etc. (servo data thereof) to the CPU 10.

The servo processing circuit 9 also performs A / D conversion on the sample and hold values of the burst signals A to F from the read / write IC 8 and sends burst outputs A to F, which are the A / D conversion results, to the CPU 10.

Here, the difference AB between the burst outputs A and B with respect to the position (center position) of the head 2 (AB characteristic).
And burst output C, D difference CD (CD characteristic)
6 shows the relationship between the burst outputs E and F and the difference EF (EF characteristic) between the burst outputs E and F. Further, (D−C) / (C + D) characteristics with respect to the position (center position) of the head 2,
(FE) / (E + F) characteristics and (AB) / (A +)
B) characteristics are shown in FIG. 7, where (EF) / (E + F) characteristics and (BA) / (A +) with respect to the position (center position) of the head 2 are shown.
B) Characteristics are shown in FIG.

The CPU 10 drives the VCM 5 via the motor driver 6 based on the cylinder data (in the servo data) sent from the servo processing circuit 9 to move the head 2 onto the target cylinder.

When the head 2 is moved to the target cylinder, the CPU 10 continuously performs position control for positioning the head 2 at the track center of the target cylinder based on the burst outputs AF sent from the servo processing circuit 9. Do the following:

First, the CPU 10 calculates the difference AB between the burst outputs A and B, and the absolute value of the value AB is the threshold value Vth.
Depending on whether or not the following, the value of A-B has a linear relationship with the head position, that is, the linear range of the A-B characteristic (for example, the range indicated by α or α'in FIG. 6). , Within the range of ± 1/4 track from the track center, excluding the area in the vicinity of the position displaced by ± 1/4 track), it is determined whether or not the head 2 is present (step S1). .

If the absolute value of the value A-B is less than the threshold value Vth, the CPU 10 indicates that the head 2 exists within the linear range (α or α ') of the A-B characteristic, and thus the burst output A , B, it is determined that the position information (positional error) of the head 2 can be accurately obtained.

In this case, if the head 2 is in the linear range (α) where the slope of the AB characteristic is positive, the CPU 10 (A−B) / (A + B) in the thick line portion in α in FIG. ) Characteristic, using the calculation formula of {(A−B) / (A + B)} * G (2), and the head 2 within the linear range (α ′) where the inclination of the A−B characteristic is negative. If there is, {(BA) / (A + B)} * G (3) by using the (BA) / (A + B) characteristic of the thick line portion in α'in FIG. The position information of the head 2 is calculated by the calculation formula (step S2).

Here, G is a correction coefficient (burst position conversion coefficient) determined by the width of the head 2 and the track width (track pitch). In the present embodiment, position information when there is a deviation of one track width. (Position error) is 2 ¹³ = 204
G such that 8 is used.

Further, which side of the head 2 is located within α (the linear range of the A-B characteristic is positive) or within α '(the linear range of the negative A-B characteristic is negative). Is determined by whether the value of CD is positive or negative, as is clear from FIG. However, when the sign (positive or negative) of the position deviation amount of the head 2 from the track center is deviated to the right direction (direction in which the track number increases) from the track center in FIGS. 6 to 8, “positive” and left. If it is deviated in the direction (direction in which the track number decreases), it is given as "negative".

As is apparent, when the head 2 exists within α, the servo processing circuit 9 decodes the cylinder data indicating the cylinder N, and therefore the head 2 from the center of the cylinder N (= track n). The positional deviation amount (normalized value) of is calculated. Further, when the head 2 exists in α ′, the cylinder data indicating the cylinder N + 1 is decoded by the servo processing circuit 9, so that the cylinder N +
The positional deviation amount (normalized value) of the head 2 from the center of 1 (= track n + 1) is obtained.

On the other hand, if the absolute value of the value A-B exceeds the threshold value Vth, the CPU 10 has the head 2 at a position outside the linear range (α, α ') of the A-B characteristic. It is determined that the burst outputs A and B cannot be used to calculate the position information of the head 2.

In this case, the CPU 10 calculates the difference C-D between the burst outputs C and D, and the value of C-D is determined by whether the absolute value of the value of C-D is the threshold value Vth or less. A range having a linear relationship with the position, that is, a linear range of the characteristic of C-D (for example, a range indicated by γ in FIG. 6, and within a range of ± 1/4 track from the track boundary, ± 1 It is determined whether or not the head 2 is present within a range excluding the area near the position shifted by / 4 track) (step S3).

If the absolute value of the value of CD is less than or equal to the threshold value Vth, the CPU 10 finds that the head 2 is within the linear range of the CD characteristic, and therefore the heads are output using the burst outputs C and D. It is determined that the position information (position error) of 2 can be accurately obtained.

In this case, if the head 2 is within the linear range where the slope of the CD characteristic is positive, the CPU 10 obtains the (CD) / (C + D) characteristic (not shown) within the linear range. Utilizing the following formula, {(C−D) / (C + D)} * G (4) and if the head 2 is in the linear range (γ) where the slope of the CD characteristic is negative. , (D−C) / (C + D) characteristics of the thick line portion in γ in FIG. 7, {(D−C) / (C + D)} * G (5) The position information of No. 2 is calculated (step S4).

Here, it can be seen from FIG. 6 which side the head 2 is located within the linear range where the slope of the CD characteristic is positive or within the linear range (γ) where the slope of the CD characteristic is negative. Obviously, it is determined by whether the value of AB is negative or positive.

The position information obtained by the above equation (4) or equation (5) indicates the amount of displacement of the head 2 from the track boundary. Therefore, in order to obtain the amount of displacement of the head 2 from the track center, it is necessary to add or subtract a normalized value of ½ track width (here, 2048/2 = 1024). In the example of the linear range (γ) of the CD characteristic in FIG. 6, which of the addition and the subtraction is used is indicated by the positive / negative of the value of AB and the cylinder data decoded by the servo processing circuit 9. It is determined by whether the cylinder number is an even number or an odd number.

For example, when the value of AB is positive (that is, when the equation (5) is used) and the cylinder number N of the track n in FIG. If the cylinder number indicated by the decoded cylinder data is even, addition is performed, and if it is odd, subtraction is performed. Further, when the value of AB is positive and the cylinder number N of the track n in FIG. 6 is odd, if the cylinder number indicated by the cylinder data decoded by the servo processing circuit 9 is even, subtraction or odd If so, it will be an addition.

On the contrary, when the value of AB is negative (that is, (4)
6) and the cylinder number N of the track n in FIG. 6 is an even number, subtraction is performed if the cylinder number indicated by the cylinder data decoded by the servo processing circuit 9 is even, and addition is performed if it is an odd number. Becomes Further, when the value of AB is negative and the cylinder number N of the track n in FIG. 6 is an odd number, if the cylinder number indicated by the cylinder data decoded by the servo processing circuit 9 is an even number, an odd number is added. If so, it becomes a subtraction.

By the way, in the linear range of the CD characteristic, γ
For example, the cylinder data decoded by the servo processing circuit 9 may be cylinder N or cylinder N + 1. Therefore, in the example in which the linear range of the CD characteristic is γ, if the cylinder N is decoded (read), the positional deviation amount of the head 2 from the center of the cylinder N (= track n) (normalized value of ) Is obtained, and if cylinder N + 1 is decoded, cylinder N + 1 (track n +
1) Positional deviation of head 2 from the center (normalized value)
Is required.

On the other hand, if the absolute value of the value of CD exceeds the threshold value Vth, the CPU 10 causes the head 2 to (only the linear range of the AB characteristic such as α and α'in FIG. 6). Not)
It is judged that the burst outputs C and D cannot be used for the calculation of the position information of the head 2, because the position is out of the linear range of the CD characteristic such as γ in FIG.

In this case, the CPU 10 is
A region where the non-linear range of the -B characteristic and the non-linear range of the CD characteristic overlap (for example, a range indicated by β or β'in FIG. 6, and is ± 1 / from the track center and the track boundary.
It is determined that the head 2 is present in a region near the position shifted by 4 tracks). This area (β, β ′) is shown in FIG.
As is clear from the above, it is a linear range of the EF characteristic.

Therefore, if the head 2 is within the linear range (β ') where the slope of the EF characteristic is positive, the CPU 10 of FIG.
Using the (E−F) / (E + F) characteristic of the thick line portion in β ′ in the formula, {(E−F) / (E + F)} * G (6) If the head 2 is within the linear range (β) where the slope of the F characteristic is negative, the (FE) / (E + F) characteristic of the thick line portion in β in FIG. E) / (E + F)} * G (7) is used to calculate the position information (position error) of the head 2 (step S5).

Here, which side of the head 2 exists in the linear range where the slope of the E-F characteristic is positive (β ') or within the linear range where the slope of the CD characteristic is negative (β). , Fig. 6
As is clear from the above, it is determined by whether the value of AB and the value of CD have different signs or the same sign.

The position information obtained by the above formula (6) or formula (7) indicates the amount of positional deviation of the head 2 based on the position deviated by ± 1/4 track from the track center. Therefore, in order to obtain the amount of displacement of the head 2 from the track center, it is necessary to add or subtract a normalized value of 1/4 track width (here, 2048/4 = 512). Here, subtraction may be performed when the expression (6) is used, and addition may be performed when the expression (7) is used.

As is apparent, when the head 2 exists within β, the servo processing circuit 9 decodes the cylinder data indicating the cylinder N, and therefore the head 2 from the center of the cylinder N (= track n). The positional deviation amount (normalized value) of is calculated. Further, when the head 2 is present in β ', the cylinder data indicating the cylinder N + 1 is decoded by the servo processing circuit 9, so that the cylinder N +
The positional deviation amount (normalized value) of the head 2 from the center of 1 (= track n + 1) is obtained.

When the CPU 10 calculates the positional information of the head 2 (normalized value of the positional deviation amount of the head 2 from the track center) in step S2, S4 or S5, the positional deviation amount (positional error amount) indicated by the positional information is calculated. The head 2 is positioned at the track center of the target cylinder by controlling the movement of the head 2 (step S6). The movement control of the head 2 is performed by driving the voice coil motor 5 via the motor driver 6.

When a reproducing / recording / separating type head (similar to the reproducing / recording / separating type head 20 shown in FIG. 10) composed of a write head and a read head is used as the head 2, data writing (data recording / data recording) is performed. ) For positioning the write head at the track center of the target cylinder, that is, for positioning the read head at a position deviated from the track center (off-track position), the read head (center of) and the write head (of Distance from center) Δ
The position error calculation result in step S2, S4 or S5 is corrected (addition or subtraction of Δ value) by (normalized interval Δ when one track pitch is 2048).
do it. In the present embodiment, even if the read head is displaced from the track center, the read head is
Since the linear range of the −D characteristic or the linear range of the EF characteristic is surely entered, correct head position information can be obtained.

In the embodiment described above, EF
The linear range of the characteristic (β, β ′), ie the AB characteristic and the C−
In the range (β, β ') in which both D characteristics are non-linear, the position information is calculated according to the above equation (6) or equation (7) using the verse outputs E and F (processing of step S5 in FIG. 5). Although described as performing, it is not limited to this. For example, instead of the process of step S5, as described below, a first position information calculation method for calculating the position information of the head 2 using a set of burst outputs A and B and a set of E and F, or burst. It is also possible to apply the second position information calculation method of calculating the position information of the head 2 using the set of outputs C and D and the set of E and F.

First, in the first position information calculation method, a range (β, β ') in which both the AB characteristic and the CD characteristic are non-linear
In the above, the A-B characteristic in the range is supplemented by the E-F characteristic which is linear in the range. This first position information calculation method will be described in order separately for the case where the head 2 exists within the range β and the case where the head 2 exists within the range β ′.

When the head 2 exists within the range of β, C
The PU 10 uses the position information of the head 2 within this range as [{(A−B) / (A + B)} * G] + [{(FE) / (E + F)} * G + Δ1] (8 ) Is calculated. Here, Δ1 is an offset, and is a value such that {(FE) / (E + F)} * G + Δ1 = 0 (9) at the boundary of α → β. The reason will be described.

First, at the boundary of α → β, {(FE) /
(E + F)} * G has a negative value as is apparent from FIG. Also, at the boundary of α → β, {(A−B) / (A +
The value of B)} * G is, as is clear from FIG.
The position of the head 2 at the boundary of β (normalized position of the head 2 with reference to the center of the track n) is shown, and is 370 (constant value) in the example of FIG.

On the other hand, the position of the head 2 within β takes a value of 370 to 654 in the example of FIG. This value is (370+
0) to (370 + 284), and α → β
When the boundary of is 0 (reference), it is equivalent to taking a value of 0-284. Therefore, {(FE) / (E +
F)} * G + Δ1 may take a value of 0 to 284, and the offset Δ1 is {(FE) / (E + F)} * G + Δ1 at the boundary of α → β as shown in the above equation (9). Value of 0
Value is used.

Next, when the head 2 exists within the range of β ', the CPU 10 obtains the position information of the head 2 within this range by [{(B-A) / (A + B)} * G]- [{(E−F) / (E + F)} * G + Δ2] (10) The calculation formula is used. Here, Δ2 is an offset and is a value such that {(E−F) / (E + F)} * G + Δ2 = 0 (11) at the boundary of α ′ → β ′.

Next, the second position information calculation method is AB
The range in which both the characteristics and the CD characteristics are non-linear (β,
In β '), the CD characteristic in the range is complemented by the EF characteristic which is linear in the range. This second
The position information calculating method will be described separately for the case where the head 2 exists within the range β and the case where the head 2 exists within the range β ′.

When the head 2 is within the range of β, C
The PU 10 uses the position information of the head 2 within this range as [{(D−C) / (C + D)} * G] − [{(F−E) / (E + F)} * G + Δ3]. ) Is calculated. Here, Δ3 is an offset, and is a value such that {(FE) / (E + F)} * G + Δ3 = 0 (13) at the boundary of γ → β.

Next, when the head 2 exists within the range of β ', the CPU 10 uses the position information of the head 2 within this range as [{(D-C) / (C + D)} * G] + [{(E−F) / (E + F)} * G + Δ4] ... (14) The calculation formula is used. Here, Δ4 is an offset, and is a value such that {(E−F) / (E + F)} * G + Δ4 = 0 (15) at the boundary of γ → β ′.

As described above, when the head 2 enters the range β or β ', that is, in the range β or β'where both the absolute value of AB and the absolute value of CD exceed the threshold value Vth. If the head 2 is inserted, instead of the process of step S5, the formula (8) or (10), or the formula (1)
The position information of the head 2 may be calculated according to the equation (2) or the equation (14).

Further, when the head 2 enters α → β, since the burst outputs A and B are used to calculate the position information in the range α, the position information of the head 2 is calculated by the above equation (8). Then it is easy to calculate. Similarly, when the head 2 enters γ → β, burst output C,
Since D is used, it is easy to calculate the position information of the head 2 by the equation (12).

Further, since the burst outputs A and B are used to calculate the position information in the range α ′ when the head 2 enters α ′ → β ′, the position of the head 2 is calculated by the above equation (10). When information is calculated, it is easy to calculate. Similarly, since the burst outputs C and D are used to calculate the position information in the range γ when the head 2 enters γ → β ′, the position information of the head 2 is calculated by the above equation (14). Easy to calculate.

In the above embodiments, the magnetic disk device has been described. However, in the present invention, the head is placed on the recording medium based on the servo data recorded on the recording medium (disk) such as a magneto-optical disk device. The present invention can be applied to general data recording / reproducing devices that perform seek / positioning control at a target position.

[0084]

As described above in detail, according to the present invention, the servo area radially arranged from the center of the recording medium across each track has a width equal to the track pitch with the center position of each track as a boundary. The first and second burst signals (A, B) that it has are recorded alternately, and the third and fourth burst signals (C, D) that have the same width as the track pitch are alternated at each track boundary. Is recorded on the track, and at a position deviating ± 1/4 track from the center position of each track,
By applying the burst data structure in which the fifth and sixth burst signals (E, F) having a width of ½ of the track pitch are alternately recorded, no matter where the head is on the disk, The linear range of the A-B characteristic, the linear range of the C-D characteristic, and the linear range of the EF characteristic can be surely included, whereby accurate head positioning control can always be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a magnetic disk drive according to an embodiment of the present invention.

FIG. 2 is an exemplary conceptual view showing a typical format example of a disc 1 applied in the embodiment.

3 is a diagram showing a format example of a servo area 110 in FIG.

FIG. 4 is a diagram showing recording positions on the tracks of burst signals A to F applied in the embodiment.

FIG. 5 is a flowchart for explaining a head positioning control operation in the same embodiment.

FIG. 6 shows a difference between a head position and burst outputs A and B (AB), a difference between burst outputs C and D (CD), and a difference between burst outputs E and F (EF) in the same embodiment. FIG.

FIG. 7 is a diagram showing a head position (D-
The figure which shows C) / (C + D) characteristic, (FE) / (E + F) characteristic, and (AB) / (A + B) characteristic.

FIG. 8 shows (E-
The figure which shows the (F) / (E + F) characteristic and the (AB) / (A + B) characteristic.

FIG. 9 shows four burst signals A to applied in the prior art.
The figure which shows the recording position on the track of D.

10 shows the relationship between the head position and the difference between burst outputs A and B (AB) and the difference between burst outputs C and D (CD) when the burst signals A to D of FIG. 7 are used. Fig.

FIG. 11 is a diagram for explaining a problem when the write head is positioned at the track center during write access using the read / write separated type head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Disk (recording medium), 2 ... Head, 5 ... Voice coil motor (VCM), 7 ... Head IC, 8 ... Read / write IC, 9 ... Servo processing circuit, 10 ... CPU (positioning control means) 11 ... ROM , 100 ... Servo sector, 110 ... Servo area, 114 ... Burst area.

Claims (8)

[Claims] 1. A large number of tracks are formed concentrically,
A recording medium for a data recording / reproducing apparatus used for recording / reproducing by a head, wherein a plurality of servo areas used for positioning of the head are radially arranged from the center of each recording medium across each track. In the servo area, first and second burst signals having the same width as the track pitch are alternately recorded with the center position of each track as a boundary, and the same as the track pitch with each track boundary as a boundary. Third and fourth burst signals having a width are alternately recorded, and ± 1 from the center position of each track.
/ 4 1 / track track pitch
A fifth burst signal and a sixth burst signal having a width of 2 are alternately recorded, and a range in which the difference between the output levels of the first and second burst signals with respect to the head position is linear, the third and the third with respect to the head position, No. 4 burst signal output level difference is linear range, and the fifth and sixth burst signal output level difference with respect to the head position is linear range difference range is linear range. A recording medium for a data recording / reproducing apparatus characterized by the above. 2. A large number of tracks are formed concentrically,
A recording medium used for recording and reproduction by a head,
A plurality of servo areas used for positioning the head and the like are arranged radially from the center across each track, and the servo area has the same width as the track pitch with the center position of each track as a boundary. The first and second burst signals are recorded alternately, and the third and fourth burst signals having the same width as the track pitch are recorded alternately at each track boundary, and further from the center position of each track. A recording medium on which fifth and sixth burst signals having a width of 1/2 of the track pitch are alternately recorded with a position displaced by ± 1/4 track, and the head read from the recording medium. The first and second burst signals are selected from among the first to sixth burst signals.
Of the burst signals, the third and fourth burst signal sets, and the fifth and sixth burst signal sets selectively using the head from the track center. A data recording / reproducing apparatus comprising: a head positioning control unit that calculates a positional deviation amount and positions the head on a target cylinder based on the positional deviation amount. 3. The head positioning control means, if the absolute value of the difference between the output levels of the first and second burst signals is within a predetermined threshold value, the set of the first and second burst signals. When the absolute value of the difference between the output levels of the third and fourth burst signals is within the threshold value, the set of the third and fourth burst signals is included. 3. The data recording / reproducing apparatus according to claim 2, wherein the set of the fifth burst signal and the sixth burst signal is selectively used. 4. A large number of tracks are formed concentrically,
A recording medium used for recording and reproduction by a head,
A plurality of servo areas used for positioning the head and the like are arranged radially from the center across each track, and the servo area has the same width as the track pitch with the center position of each track as a boundary. The first and second burst signals are recorded alternately, and the third and fourth burst signals having the same width as the track pitch are recorded alternately at each track boundary, and further from the center position of each track. A recording medium on which fifth and sixth burst signals having a width of 1/2 of the track pitch are alternately recorded with a position displaced by ± 1/4 track, and the head read from the recording medium. Of the first to sixth burst signals, the first and second burst signals
If the absolute value of the difference between the output levels of the burst signals is within a predetermined threshold, the pair of the first and second burst signals is set to the absolute value of the difference between the output levels of the third and fourth burst signals. When the value is within a predetermined threshold, the third and fourth burst signal sets are set, and when the value is neither of them, the first, second, fifth and sixth burst signal sets or The third to sixth burst signal groups are selectively used to calculate the amount of positional deviation of the head from the track center, and the head is positioned in the target cylinder based on the amount of positional deviation. A data recording / reproducing apparatus comprising a head positioning control means. 5. The positioning control means selects the set of the first, second, fifth and sixth burst signals, based on the set of the first and second burst signals. When the calculated positional deviation amount is corrected based on the fifth and sixth burst signal sets and the third to sixth burst signal sets are selected, the third and fourth burst signal sets are selected. 5. The data recording / reproducing apparatus according to claim 4, wherein the position deviation amount calculated based on the set of burst signals is corrected based on the set of the fifth and sixth burst signals. 6. Radial from the center across each track,
A plurality of servo areas used for positioning a head for recording and reproducing data are arranged, and the servo areas have first and first servo areas having the same width as the track pitch with the center position of each track as a boundary. Two burst signals are alternately recorded, and third and fourth burst signals having the same width as the track pitch are alternately recorded at each track boundary, and ± 1/4 from the center position of each track. A head positioning control method in a data recording / reproducing apparatus provided with a recording medium on which fifth and sixth burst signals having a width of ½ of a track pitch are alternately recorded with a track offset position as a boundary, Of the first to sixth burst signals read from the recording medium by the head, the first and second burst signals are selected.
Selecting one of the burst signal set, the third and fourth burst signal set, and the fifth and sixth burst signal set, and using the selected burst signal set. A head positioning control method in a data recording / reproducing apparatus, characterized in that a positional deviation amount of the head from a track center is calculated and the head is positioned on a target cylinder based on the positional deviation amount. 7. When the absolute value of the difference between the output levels of the first and second burst signals is within a predetermined threshold, the set of the first and second burst signals is set to the third and third burst signals. Four
If the absolute value of the difference between the output levels of the burst signals is within the threshold value, the third and fourth burst signal pairs are included, and if neither is the fifth burst signal, the fifth burst signal. 7. A set of is selected.
A head positioning control method in the described data recording / reproducing apparatus. 8. Radial from the center across each track,
A plurality of servo areas used for positioning a head for recording and reproducing data are arranged, and the servo areas have first and first servo areas having the same width as the track pitch with the center position of each track as a boundary. Two burst signals are alternately recorded, and third and fourth burst signals having the same width as the track pitch are alternately recorded at each track boundary, and ± 1/4 from the center position of each track. A head positioning control method in a data recording / reproducing apparatus provided with a recording medium on which fifth and sixth burst signals having a width of ½ of a track pitch are alternately recorded with a track offset position as a boundary, Of the first to sixth burst signals read from the recording medium by the head, the first and second burst signals
If the absolute value of the difference between the output levels of the burst signals is within a predetermined threshold, the pair of the first and second burst signals is set to the absolute value of the difference between the output levels of the third and fourth burst signals. When the value is within a predetermined threshold, the third and fourth burst signal sets are set, and when the value is neither of them, the first, second, fifth and sixth burst signal sets or The third to sixth burst signal groups are selectively used to calculate the amount of positional deviation of the head from the track center, and the head is positioned in the target cylinder based on the amount of positional deviation. A head positioning control method in a data recording / reproducing apparatus, comprising: