JP4198174B2 - Disk device and disk medium - Google Patents

Description

  The present invention divides a plurality of servo cylinders formed concentrically from an inner diameter portion to an outer diameter portion of a disk such as a magnetic disk into several areas, and sets different servo signal frequencies for each divided area. The present invention relates to a disk device in which servo signal frequencies are recorded in advance, and a disk medium.

  Here, a disk that is rotatably positioned on a disk device such as a magnetic disk device may be removable from the disk device, such as when used as a single plate STW (Servo Track Writer). . In this case, the disk may be shipped alone with the servo signal pattern written in the servo cylinder. Such a disk is generally called a “disk medium” or “disk medium”.

  FIG. 1 is a schematic diagram illustrating an arrangement example of general servo signals, and FIG. 2 is a diagram illustrating a relationship between a magnetization reversal pattern of a servo signal recorded at a constant servo signal frequency and a reproduced servo signal waveform. .

  As shown in FIG. 1, the servo signal pattern SSP in the conventional magnetic disk apparatus is generally based on a plurality of servo cylinders 200 concentrically formed from the inner diameter portion to the outer diameter portion of the disk 100. The signal frequency was recorded so as to be constant. Therefore, the servo signal pattern area is arranged in a fan shape on the disk 100.

  Here, the “servo cylinder” is a servo track on which a servo signal is to be formed on each disk when a plurality of disks are stacked and accessed simultaneously by a plurality of read / write heads. It is a term indicating a collection of a plurality of vertical servo tracks that can be performed (that is, a plurality of servo tracks in a cylindrical shape).

  This is because the magnetic disk device rotates the disk 100 at a constant speed, and therefore the distance of rotation in the same time is because the outer diameter part (outer side) is longer than the inner diameter part (inner side) of the disk. For this reason, when the servo signal pattern having the same number of bits is recorded with a constant servo signal frequency using the read / write head 500 supported by the arm 400, the outer servo signal pattern occupies the inner area. Will be bigger than. That is, the recording density of the outer servo signal pattern tends to be smaller than the recording density of the inner servo signal pattern.

  Therefore, in order to perform recording by setting the servo signal frequency of the outer servo cylinder higher than the servo signal frequency on the inner side, and relatively reducing the occupied area of the outer servo signal pattern, as described below. A prior art variable servo signal frequency recording scheme was invented.

  In general, as shown in FIG. 2, when a servo signal pattern is recorded at a constant servo signal frequency for a plurality of servo cylinders on the disk surface, the outer side (outer diameter portion) / center side (intermediate portion) / inner side ( In the inner diameter portion, even if the servo signal frequency is equal, the waveform of the reproduced servo signal reproduced from the magnetization reversal pattern of the servo signal is different. This is because the recording density of the servo signal pattern is higher on the inner side and lower on the outer side, so that the waveform of the reproduced servo signal is different even though the same servo signal pattern is written. Because it will be different.

  Therefore, in the read channel that demodulates the servo information from the servo signal waveform, as shown in the graph of FIG. 3, the servo signal error rate of the gray code having the servo cylinder information changes with respect to the recording density of the servo signal pattern. It is supposed to be. In order to enable the disk device to be used with a relatively good characteristic of the servo signal error rate of the Gray code, it is necessary to make the recording density of the servo signal pattern substantially constant.

  From this point of view, the recording density of servo signal patterns is almost constant by adopting the conventional variable servo signal frequency method that records servo signal patterns by changing the servo signal frequency from the inner side to the outer side of the disk. Therefore, it is expected that the error rate of the Gray code can be improved.

  Here, for reference, five patent documents related to the prior art are presented.

Japanese Patent Laid-Open No. 3-130968 JP-A-5-174516 JP-A-5-94674 JP-A-10-255416 Patent Publication No. 297247

  FIG. 4 is a schematic diagram showing an arrangement example of servo signal patterns using the conventional technique as described above. Here, an arrangement example of a servo signal pattern using a typical variable servo signal frequency method in the prior art will be exemplified (if necessary, the above-mentioned five patent documents, Japanese Patent Laid-Open No. Hei 3). No. -130968, JP-A-5-174516, JP-A-5-94674, JP-A-10-255416, and Japanese Patent No. 297247). In the example of FIG. 4, the plurality of servo cylinders 200 of the disk 100 are divided into three regions (PP0, PP1, and PP2) from the inner side to the outer side, and servos are performed at different servo signal frequencies (Fs0, Fs1, and Fs2) for each region. This is an example in which a signal pattern is recorded.

  FIG. 5 is a schematic diagram showing an example of the trajectory of the read / write head when an error is included in the estimated position of the read / write head in the conventional variable servo signal frequency method. FIG. It is a figure which shows the reproduction | regeneration servo signal waveform in the boundary of a different servo signal pattern in a servo signal frequency system.

  Regarding the servo signal demodulation function of the current read channel, only the servo signal of the servo signal frequency set in advance so that the servo signal demodulation function can be demodulated accurately. There is a read channel that can also demodulate a servo signal with a servo signal frequency that deviates from a servo signal frequency set in advance so that the servo signal demodulation function works, but the allowable frequency deviation range is very narrow.

  Therefore, if the servo signal frequency of the servo signal pattern read by the read / write head 500 (that is, the servo signal pattern read by the read / write head 500) is changed using the conventional variable servo signal frequency method, the servo of the read channel is changed. It is necessary to set the signal frequency setting in advance. In order to set the servo signal frequency in advance, the position of the read head when the next servo signal pattern is read (when the next servo signal pattern is read) is estimated using the servo information demodulated so far.

  When the read / write head performs a seek operation, the position of the read / write head at the time of reading the next servo signal pattern is estimated. If this estimated position is always accurately estimated, there is no problem.

  However, if the estimated position value includes an error, for example, the estimated read / write head position indicates the servo signal pattern area PP0 and the first area written at the first servo signal frequency Fs0. Read / write head that is estimated to be the area where the read / write head has actually reached is assumed to be near the boundary (B01) with the area PP1 of the servo signal pattern written at the second servo signal frequency Fs1 adjacent to The servo signal frequency that is different from the servo signal frequency of the area where the read / write head actually arrives is set in the read channel and the servo information cannot be demodulated. Occurs.

  During a low-speed seek operation, while reading several servo signal patterns, the read / write head causes the servo signal pattern area written at the first servo signal frequency and the second servo signal adjacent to the first area. If the estimated position of the read / write head contains an error when passing near the boundary with the servo signal pattern area written in frequency, the servo signal frequency area to which the estimated position of the read / write head belongs and the actual position Since the position of the read / write head and the servo signal frequency area are different, and the servo signal frequency setting of the read channel is different from the servo signal frequency of the servo signal that is actually read, the servo signal cannot be demodulated.

  Further, when the next servo signal pattern is read, since the position of the read / write head is estimated without the previous accurate position information, the estimated trajectory in which the error has occurred is estimated again. Therefore, the servo signal frequency is set differently from the actual read / write head position.

  Assuming that the actual position and estimated position of the read / write head have moved as shown in FIG. 5, an area different from the actual position of the read / write head once regarding the servo signal frequency setting of the read channel. If the servo signal frequency is set, the servo signal frequency setting may fail continuously and the servo signal cannot be demodulated, resulting in a problem that a seek error occurs.

  When the read / write head is in an on-track state at the boundary between servo signal pattern areas written at different servo signal frequencies, servo signal patterns at different servo signal frequencies on both sides will be read simultaneously. As shown in FIG. 6, the waveform read by the write head is a composite waveform of the reproduced servo waveforms in the two areas.

  At this time, if the servo signal frequency Fs0 is set in the read channel, the servo signal component written at the servo signal frequency Fs1 in the read servo signal becomes noise. Since this noise is highly correlated with the servo signal, the error rate of the servo signal having the servo signal frequency Fs0 is deteriorated and many demodulation errors occur. Therefore, the read / write head is turned on at an accurate position. The problem arises that it becomes impossible to track.

  The present invention has been made in view of the above problems, and when the read / write head performs a seek operation, by accurately estimating the position of the read / write head at the time of reading the next servo signal pattern, An object of the present invention is to provide a disk device and a disk medium capable of demodulating a servo signal of an actual read / write head position without error over the entire area from the inner diameter portion to the outer diameter portion of the disk. .

  In order to solve the above problems, the present invention divides a plurality of servo cylinders formed concentrically from an inner diameter portion to an outer diameter portion of a disk into predetermined areas, and sets different servo signal frequencies for each divided area. In each area, a servo signal pattern corresponding to the servo signal frequency set for each area is arranged, and the servo signal frequency set for each area is stored in advance. In the apparatus, the recording density of the servo signals recorded on the disk is set so that the demodulation characteristics of the servo signals are within a relatively good range, and the servo cylinders are divided into predetermined areas and areas. Provided is a disk device configured to set the servo signal frequency every time.

  Furthermore, a preferred embodiment of the present invention divides a plurality of servo cylinders formed concentrically from the inner diameter portion to the outer diameter portion of the disk into predetermined regions, and sets different servo signal frequencies for each divided region, In each area, a servo signal pattern corresponding to each servo signal frequency set for each area is arranged, and the servo signal frequency set for each area is stored in advance in the disk device, At the boundary between the divided first servo signal frequency region and the second servo signal frequency region adjacent to the first servo signal frequency region, the servo signal frequency in the first servo signal frequency region is the boundary. The servo signal pattern written with the servo signal pattern written at the servo signal frequency in the second servo signal frequency area is the same. To provide a disk apparatus which provide a region disposed on da.

  Further preferably, in the disk device of the present invention, the servo signal pattern arranged in the servo signal frequency region and the servo signal pattern written at two different servo signal frequencies are arranged on the same servo cylinder. Of the servo signal patterns arranged in the region, a servo signal pattern having the same servo signal frequency is arranged in phase at the head of the servo signal pattern.

  On the other hand, in another preferred embodiment of the present invention, the servo cylinder formed concentrically from the inner diameter portion to the outer diameter portion of the disk is divided into several regions, and different servo signal frequencies are assigned to the divided regions. In each area, a servo signal pattern corresponding to the servo signal frequency set for each area is arranged, and the servo signal frequency set for each area is stored in advance. In the apparatus, a servo signal pattern written at a servo signal frequency set in the first servo signal frequency region and a first servo signal frequency region adjacent to the first servo signal frequency region in the first servo signal frequency region. Servo signal frequency set in the servo signal frequency region of 2 or the third servo signal frequency region adjacent to the first servo signal frequency region. To provide a disk device to place the servo signal patterns written by the number on the same servo cylinders.

  On the other hand, in another preferred embodiment of the present invention, the servo cylinder formed concentrically from the inner diameter portion to the outer diameter portion of the disk is divided into several regions, and a central servo signal is divided for each divided region. The frequency is set, and in each area, a servo signal pattern corresponding to the center servo signal frequency set for each area is arranged, and the center servo signal frequency set for each area is stored in advance. The recording density of the servo signal recorded on the disk is set so that the demodulation characteristic of the servo signal falls within a relatively good range, and the central servo set for each area is set. Provided is a disk device in which a servo signal pattern in which the servo signal frequency is changed is arranged for each of the servo cylinders around a signal frequency.

  On the other hand, in another preferred embodiment of the present invention, the servo cylinder formed concentrically from the inner diameter portion to the outer diameter portion of the disk is divided into several regions, and the servo signal frequency is different for each divided region. In each area, a servo signal pattern of the servo signal frequency set for each area is arranged, and a single servo signal from the inner diameter portion to the outer diameter portion of the disk is placed on the same servo cylinder. Provided is a disk device for arranging servo signal patterns written in frequency.

  Furthermore, a preferred embodiment of the present invention divides a plurality of servo cylinders formed concentrically from the inner diameter portion to the outer diameter portion of the disk surface into predetermined regions, and sets different servo signal frequencies for the divided regions. In each of the areas, a divided first servo signal frequency area and a first servo signal frequency area in a disk medium in which a servo signal pattern having a servo signal frequency set for each area is arranged. The servo signal pattern written at the servo signal frequency in the first servo signal frequency region and the servo signal frequency in the second servo signal frequency region at the boundary with the second servo signal frequency region adjacent to A disk medium is provided which provides an area where servo signal patterns written in the above are arranged on the same servo cylinder.

  On the other hand, in another preferred embodiment of the present invention, a plurality of servo cylinders formed concentrically from the inner diameter portion to the outer diameter portion of the disk surface are divided into predetermined areas, and servo signals different for each of the divided areas. In the disk medium in which the servo signal pattern having the frequency of the servo signal set for each area is arranged in each area, the first servo signal is set in the area of the first servo signal frequency. The servo signal pattern written at the servo signal frequency set in the frequency region and the second servo signal frequency region adjacent to the first servo signal frequency region, or the first servo signal frequency region The servo signal pattern written at the servo signal frequency set in the third servo signal frequency area adjacent to the disk is arranged on the same servo cylinder. It provides a medium.

  On the other hand, according to still another preferred embodiment of the present invention, a plurality of servo cylinders formed concentrically from the inner diameter portion to the outer diameter portion of the disk surface are divided into predetermined regions, and a center is provided for each divided region. In the disk medium for setting the frequency of the servo signal, the recording density of the servo signal recorded on the disk is set at the center set for each region so that the demodulation characteristic of the servo signal falls within a relatively good range. Provided is a disk medium in which a servo signal pattern in which the servo signal frequency is changed is arranged for each servo cylinder with a servo signal frequency as a center.

  On the other hand, in another preferred embodiment of the present invention, the servo cylinder formed concentrically from the inner diameter part to the outer diameter part of the disk surface is divided into predetermined areas, and the servo signal frequency is different for each divided area. In each area, a servo signal pattern of the servo signal frequency set for each area is arranged, and a single servo signal from the inner diameter portion to the outer diameter portion of the disk is placed on the same servo cylinder. Provided is a disk medium on which servo signal patterns written in frequency are arranged.

  In summary, in the present invention, the recording density of the servo signal recorded from the inner diameter portion to the outer diameter portion of the disk is set so that the demodulation characteristic of the servo signal falls within a relatively good range, and a plurality of servo cylinders Is divided into several areas and the servo signal frequency is set for each area, so that when the read / write head performs a seek operation, the read / write at the time of reading the next servo signal pattern is performed. The head position can be accurately estimated, and the servo signal of the actual read / write head position can be demodulated without error over the entire area from the inner diameter portion to the outer diameter portion of the disk.

  Further, according to the present invention, a plurality of servo cylinders are divided into several regions from the inner diameter portion to the outer diameter portion of the disk, and the divided first servo signal frequency region and the first servo signal frequency region are divided. Written at the servo signal frequency in the first servo signal frequency area and the servo signal frequency in the second servo signal frequency area at the boundary with the second servo signal frequency area adjacent to Since the area where the read servo signal pattern is located on the same servo cylinder is provided, when the read / write head performs a seek operation, the read / write at the time of reading the next servo signal pattern is performed. The position of the head can be accurately estimated, and the servo signal can be demodulated with high servo demodulation quality.

  The configuration and operation of a preferred embodiment of the present invention will be described below with reference to the accompanying drawings (FIGS. 7 to 38).

  FIG. 7 is a plan view showing a schematic configuration of a mechanism portion of the disk device according to the embodiment of the present invention, FIG. 8 is a front view showing a schematic configuration of the mechanism portion of the disk device according to the embodiment, and FIG. FIG. 9 is a block diagram showing the configuration of the control unit of the disk device according to the embodiment.

  However, here, as an embodiment of the disk apparatus of the present invention, a disk apparatus 1 such as a magnetic disk apparatus for writing and reading data on a rotating disk (or disk medium) 2 such as a hard disk is illustrated. . Further, FIGS. 7 and 8 illustrate a mechanism unit of the disk device 1 according to various embodiments of the present invention described later, and FIG. 9 illustrates a control unit for controlling the operation of the disk device 1. Has been. Hereinafter, the same components as those described above are denoted by the same reference numerals.

  The disk device 1 shown in FIG. 7 and FIG. 8 roughly includes a disk enclosure 2 for mechanically protecting the disk 10, the read / write head 15, the control unit and the like in the disk device, and the read / write head. 15 and a printed circuit assembly 3 on which a control unit for controlling a data writing operation and a data reading operation by 15 is mounted. In the disk enclosure 2, a rotating disk 10 such as a single hard disk or a plurality of hard disks that are rotationally driven by a spindle motor 12 coupled to a spindle 11 is coaxially provided. The rotation direction (arrow A) of the disk 10 can be either counterclockwise or clockwise by controlling the operation of the spindle motor 12 by a servo controller 26 (see FIG. 9, abbreviated as SVC in FIG. 9). ing. A plurality of tracks (or a plurality of cylinders) are formed on the magnetic recording surface on the front surface (or back surface) of the disk 10, and a data pattern corresponding to predetermined data at an arbitrary position (also referred to as a sector) of these tracks. Has been written.

  More specifically, in the disk device using the servo surface servo system, a servo signal pattern corresponding to a servo signal for servo control is formed on the magnetic recording surface of any one of the plurality of disks 10. It is a servo surface, and the magnetic recording surfaces of the other disks are all data surfaces on which data patterns are formed. On the other hand, in a disk device using the data surface servo system, both a data pattern and a servo signal pattern are formed on each magnetic recording surface of a plurality of disks. However, in the embodiment of the present invention, the disk device using the latter data surface servo system is targeted.

  Further, in the disk device 1 shown in FIGS. 7 and 8, data is written at an arbitrary position on the magnetic recording surface of the disk 10 and at the same time a read / write for reading out the data written at an arbitrary position on the magnetic recording surface. A write head 15 is provided. The read / write head 15 is mounted on the tip of a head support arm 14. The arm 14 is moved between the position of the inner peripheral portion and the outer peripheral portion of the disk 10 by a voice coil motor (usually abbreviated as VCM) 13 controlled by a servo controller 26 (see FIG. 9) described later. Are driven to reciprocate. This makes it possible to access all data areas in which data is written on the magnetic recording surface of the disk 10.

  For example, when the arm 14 is rotated in the direction of arrow B by the voice coil motor 13, the read / write head 15 moves in the radial direction of the disk 10, and a desired track can be scanned.

  A ramp mechanism 16 is disposed on the outer periphery of the disk 10 and is engaged with the tip of the arm 14 to hold the read / write head 15 away from the disk 10.

  Further, as shown in FIG. 9, the disk device 1 is provided with an interface connector (not shown) for connecting the control unit in the magnetic disk device and the external host system 4.

  In FIG. 9, the reproduction signal read from the disk 10 by the read / write head 15 is supplied to the head IC 17, amplified, and then supplied to the printed circuit assembly 3.

  The printed circuit assembly 12 includes a hard disk controller (HDC) 21, a RAM (Random Access Memory) 22, a flash ROM (FROM) 23, an MPU (Microprocessor Unit) 24, a read channel (RDC) 25, a servo controller. (SVC) 26 and drivers 27 and 28 are included. The reproduction signal supplied from the head IC 17 is supplied to the read channel 25 on the printed circuit assembly 3 and demodulates data information and servo positioning information.

  Further, the servo positioning information demodulated by the read channel 25 is supplied to the MPU 24. The MPU 24 operates according to a program stored in advance in the flash ROM 23 and supplies information obtained by processing the supplied servo positioning information to the servo controller 26. The MPU 24 controls the voice coil motor 13 via the servo controller 26 to perform operations such as seeking the read / write head 15 to the designated track position. The MPU 24 also functions as head position estimating means for estimating the position of the read / write head 15 in advance when the seek operation of the read / write head 15 is executed.

  The configuration of the control unit as described above is basically the same as the configuration of the control unit of a generally used disk device.

  FIG. 10 is a layout diagram of servo signal patterns in the first embodiment of the present invention. However, here, the state of the servo signal pattern formed in the servo cylinder 20 of the single disk 10 is shown as a representative.

  In the first embodiment of FIG. 10, recording is performed by changing the recording density of the servo signal pattern on the disk in the area where the servo signal is written on the disk surface. Here, the area from the inner side to the outer side of the disk 10 in the servo cylinder 20 is divided into two areas (P0, P1).

  Different servo signal frequencies Fs0 and Fs1 are set for each of the divided servo cylinder regions, and servo signal patterns corresponding to the set servo signal frequencies are respectively arranged.

  On the other hand, the servo signal frequency is set so that the error rate characteristic of the servo sync mark, the error rate characteristic of the gray code, and the dispersion characteristic of the burst value are relatively good.

  Further, the servo signal written at the servo signal frequency Fs0 is located at the boundary between the area P0 where the servo signal pattern written at the servo signal frequency Fs0 is arranged and the area P1 where the servo signal pattern written at the servo signal frequency Fs1 is arranged. An area P01 is provided in which the pattern and the servo signal pattern written at the servo signal frequency Fs1 are arranged on the same servo cylinder.

  On the servo cylinder in the region P01 where two servo signal patterns exist, the servo signal pattern written at the servo signal frequency Fs0 and the servo signal pattern written at the servo signal frequency Fs1 are alternated for each servo signal pattern. To place.

  In the embedded servo system corresponding to the data surface servo system, the servo signal pattern is arranged across the data area. Therefore, the next servo signal pattern is read until the next servo signal pattern is read during the seek operation of the read / write head. It is necessary to estimate the position of the read / write head when reading data, and the estimation error of the position of the read / write head must be taken into consideration. In the area where the servo signal pattern written at the servo signal frequency Fs0 and the servo signal pattern written at the servo signal frequency Fs1 are arranged on the same servo cylinder, the maximum position estimation error when estimating the position of the read / write head The width of the servo cylinder is twice as large as that of the servo cylinder.

  FIGS. 11 to 13 are first to third flowcharts for explaining the seek operation in the first embodiment of the present invention, respectively.

  First, as shown in step S10, when a seek command is issued, the position of the read / write head in the next servo signal pattern is determined from the servo information related to the read / write head position, the VCM current, etc. Is estimated (step S11).

  The correspondence table between the servo cylinder and the area is compared with the estimated read / write head position (servo cylinder) to determine the area to which the estimated read / write head position belongs (step S12).

  Furthermore, the estimated read / write head position (may be abbreviated as the read / write head estimated position in the figure) was written with two servo signal frequencies newly arranged at the boundary of the servo signal frequency area. A servo signal that is an area where a servo signal pattern exists (step S13 in FIG. 11) and the estimated read / write head position is written at two servo signal frequencies to which the estimated read / write head position belongs. If the disk is on the outer side of the servo cylinder at the center of the area where the pattern exists (step S14 in FIG. 12), the read channel servo signal frequency is estimated before reading the next servo signal pattern. The area of the servo signal pattern written at the two servo signal frequencies to which the write head position belongs exists. Setting the servo signal frequency is set to a region of the servo signal frequency that is in contact with the coater side (step S15 in FIG. 12).

  On the other hand, the estimated read / write head position is an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area (step S13 in FIG. 11). ) And the estimated read / write head position is larger than the servo cylinder in the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is located. (Step S14 in FIG. 12), before reading the next servo signal pattern, read the servo signal frequency of the read channel with two servo signal frequencies to which the estimated read / write head position belongs. It is set for the servo signal frequency area that touches the inner side of the area where the signal pattern exists. Setting the servo signal frequency (step S16 in FIG. 12).

  On the other hand, when the estimated read / write head position is not a region where there is a servo signal pattern newly written at two servo signal frequencies arranged at the boundary of the servo signal frequency region (step of FIG. 11). S13) When the estimated read / write head position belongs to an area different from the servo signal frequency area to which the latest (to date) position belongs (step S17 in FIG. 12), the next servo signal pattern Is read, the servo signal frequency of the read channel is set to the servo signal frequency in the servo signal frequency region to which the estimated read / write head position belongs (step S18 in FIG. 12).

  On the other hand, when the estimated read / write head position is not a region where there is a servo signal pattern newly written at two servo signal frequencies arranged at the boundary of the servo signal frequency region (step of FIG. 11). S13) When the estimated position of the read / write head belongs to the same area as the servo signal frequency area to which the latest (to date) position belongs (step S17 in FIG. 12), the servo signal of the read channel The frequency setting is not changed (step S19 in FIG. 12).

  Further, as shown in step S20 of FIG. 13, the next servo signal pattern is read and servo demodulation is performed.

  If servo demodulation cannot be performed (due to a servo sync mark detection error) (step S21), head positioning is executed using the estimated read / write head position (step S23).

  On the other hand, when the servo demodulation can be performed (because servo sync mark detection has been performed normally) (step S21), the demodulated positioning information is stored in the memory (for example, the RAM in FIG. 9) and newly obtained. Head positioning is executed using the obtained positioning information (step S22).

  When the position of the read / write head is a servo cylinder for seek (step S24), the seek operation is terminated (step S25). When the servo cylinder is not for seek, the next servo signal pattern is read again. The read / write head position is estimated and the seek operation is repeated.

  FIG. 14 is a schematic diagram showing the estimated position of the read / write head in the first embodiment of the present invention. The effect of the first embodiment will be described with reference to FIG.

  According to the first embodiment, as a result of estimating the position of the read / write head when reading the next servo signal pattern during the seek operation of the read / write head, the estimated position of the read / write head is: When the boundary between the servo signal frequency area and the servo signal frequency area, that is, the servo signal pattern written at the two newly provided servo signal frequencies is located on the same servo cylinder Even if the estimated read / write head position contains an estimation error and the estimated read / write head position is different from the actual position where the read / write head arrives, the two newly provided servo signals In the area where servo signal patterns written in frequency are placed on the same servo cylinder, the number of cylinders is double the estimated error. To have.

  Therefore, by setting the servo signal frequency of the read channel to one of the servo signal frequencies, servo signal patterns of two different servo signal frequencies that are alternately arranged on the servo cylinder for each servo signal pattern. Can be demodulated with a probability of 1/2.

  On the other hand, when the servo signal pattern written with two newly provided servo signal frequencies passes near the area arranged on the same servo cylinder during low-speed seek operation, Even if the servo signal frequency of the read channel is different from the servo signal frequency of the read servo signal and the servo signal cannot be demodulated, the servo signal to be read next is Servo signal frequency set to the read channel servo signal frequency, and the servo signal can be demodulated, so it is possible to prevent seek errors that would prevent some servo signals from being demodulated continuously. is there.

  FIG. 15 is a layout diagram of servo signal patterns in the second embodiment of the present invention. Here, however, the state of the servo signal pattern formed on the servo cylinder 20 of the single disk 10 is shown as a representative.

  In the second embodiment of FIG. 15, recording is performed by changing the recording density of the servo signal pattern on the disk surface in the area where the servo signal is written on the disk surface. Here, the servo cylinder 20 is divided into two regions (P0, P1) from the inner side to the outer side of the disk 10.

  Different servo signal frequencies Fs0 and Fs1 are set for each of the divided servo cylinder regions, and servo signal patterns of the set servo signal frequencies are respectively arranged.

  On the other hand, the servo signal frequency is set so that the error rate characteristic of the servo sync mark, the error rate characteristic of the gray code, and the dispersion characteristic of the burst value are relatively good.

  Further, the servo signal written at the servo signal frequency Fs0 is located at the boundary between the area P0 where the servo signal pattern written at the servo signal frequency Fs0 is arranged and the area P1 where the servo signal pattern written at the servo signal frequency Fs1 is arranged. An area P01 is provided in which the pattern and the servo signal pattern written at the servo signal frequency Fs1 are arranged on the same servo cylinder.

  The servo signal pattern written at the servo signal frequency Fs0 and the servo signal pattern written at the servo signal frequency Fs1 are arranged on the same servo cylinder. In the region P01 where two servo signal patterns exist, different servo signal frequencies. Servo signal patterns having two different servo signal frequencies are arranged continuously in the circumferential direction of the disk so as not to be read simultaneously by the read / write head.

  On the other hand, even if the two servo signal patterns exist and the servo signal frequency area is different, the servo signal pattern written with the same servo signal frequency will be placed in the servo signal frequency area. Arrange the signal pattern head and phase so that they are aligned.

  In the embedded servo system, the servo signal pattern is placed across the data area. Therefore, when the read / write head seeks, the next servo signal pattern is read until the next servo signal pattern is read. It is necessary to estimate the position of the head, and this read / write head position estimation error must be considered. In the area where the servo signal pattern written at the servo signal frequency Fs0 and the servo signal pattern written at the servo signal frequency Fs1 are arranged on the same servo cylinder, the maximum position estimation error when estimating the position of the read / write head The width of the servo cylinder is twice as large as that of the servo cylinder.

  FIGS. 16 to 18 are first to third flowcharts for explaining the seek operation in the second embodiment of the present invention, respectively.

  First, as shown in step S30, when a seek command is issued, the position of the read / write head in the next servo signal pattern is determined based on the stored servo information, VCM current, etc. regarding the read / write head position. Is estimated (step S31).

  The correspondence table between the servo cylinder and the area is compared with the estimated read / write head position to determine the area to which the estimated read / write head position belongs (step S32).

  Further, the estimated position of the read / write head is an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area (step S33 in FIG. 16). In addition, the estimated read / write head position is on the outer side of the disk from the servo cylinder at the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is located. If so (step S34 in FIG. 17), before reading the next servo signal pattern, the servo signal frequency of the read channel is the servo signal written with the two servo signal frequencies to which the estimated read / write head position belongs. Set for the servo signal frequency area that touches the outer side of the area where the pattern exists Set to turbo signal frequency (step S35 in FIG. 17).

  On the other hand, the estimated read / write head position is an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area (step S33 in FIG. 16). ) And the estimated read / write head position is higher than the servo cylinder at the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is present. If it is on the inner side (step S34 in FIG. 17), before reading the next servo signal pattern, the servo signal frequency of the read channel is written with the two servo signal frequencies to which the estimated read / write head position belongs. Set for the servo signal frequency area that touches the inner side of the area where the servo signal pattern exists. Set to a servo signal frequency (step S36 in FIG. 17).

  On the other hand, when the estimated read / write head position is not an area where there is a servo signal pattern newly written at two servo signal frequencies arranged at the boundary of the servo signal frequency area (step of FIG. 16). S33) When the estimated read / write head position belongs to an area different from the servo signal frequency area to which the latest (to date) position belongs (step S37 in FIG. 17), the next servo signal pattern Is read, the servo signal frequency of the read channel is set to the servo signal frequency in the servo signal frequency region to which the estimated read / write head position belongs (step S38 in FIG. 17).

  On the other hand, when the estimated read / write head position is not an area where there is a servo signal pattern newly written at two servo signal frequencies arranged at the boundary of the servo signal frequency area (step of FIG. 16). S33) When the estimated read / write head position belongs to the same area as the servo signal frequency area to which the latest (to date) position belongs (step S37 in FIG. 17), the servo signal of the read channel The frequency setting is not changed (step S39 in FIG. 17).

  Further, when the estimated read / write head position is an area where servo signal patterns written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area exist, the read / write head positions are continuously read. Each of the two servo signals is demodulated (step S40 in FIG. 17).

  Since the servo signal frequency of the read channel is set to one of two different servo signals, the servo signal can always be demodulated with respect to one of the two servo signals (FIG. 18). Steps S41 to S44).

  Of the two servo signal demodulation results, head positioning is executed using the positioning information of the one that could be demodulated (because the servo sync mark was normally detected) (step S45 in FIG. 18).

  If the estimated read / write head position is not an area where there is a servo signal pattern written with two servo signal frequencies newly placed at the boundary of the servo signal frequency area, the next servo signal pattern is read. Servo demodulation is executed (step S46 in FIG. 17).

  If servo demodulation cannot be performed (due to a servo sync mark detection error) (step S47 in FIG. 18), head positioning is executed using the estimated read / write head position (step S45 in FIG. 18). ).

  On the other hand, when the servo demodulation can be performed (because the servo sync mark has been detected normally) (step S47 in FIG. 18), the demodulated positioning information is stored in the memory (step S48 in FIG. 18). Head positioning is executed using the newly obtained positioning information (step S49 in FIG. 18).

  If the position of the read / write head is a seek-purpose servo cylinder (step S50 in FIG. 18), the seek operation is terminated (step S51 in FIG. 18). Estimate the position of the read / write head when reading the servo signal pattern and repeat the seek operation.

  In the second embodiment, when the servo cylinders in the on-track state are areas where servo signal patterns written at the servo signal frequencies Fs0 and Fs1 exist, they are continuously arranged as in the seek operation. The servo signal can be demodulated by continuously reading two servo signal patterns having different servo signal frequencies.

  FIG. 19 is a schematic diagram showing the estimated position of the read / write head in the second embodiment of the present invention. The effects of the second embodiment will be described with reference to FIG.

  According to the second embodiment, as a result of estimating the position of the read / write head when reading the next servo signal pattern during the seek operation of the read / write head, the estimated position of the read / write head is: When the boundary between the servo signal frequency area and the servo signal frequency area, that is, the servo signal pattern written at the two newly provided servo signal frequencies is located on the same servo cylinder Even if the estimated read / write head position contains an estimation error and the estimated read / write head position is different from the actual position where the read / write head arrives, the two newly provided servo signals The area where servo signal patterns written in frequency are arranged on the same servo cylinder has twice as many cylinders as the estimation error. It has become way.

  Therefore, by setting the servo signal frequency of the read channel to one of the servo signal frequencies, the servo signal pattern written at two different servo signal frequencies arranged continuously in the circumferential direction is read. Since the servo signal is demodulated, it is possible to always demodulate one of the servo signal patterns. Therefore, a servo signal demodulation error does not occur due to the servo channel frequency setting factor of the read channel.

  On the other hand, even during a low-speed seek operation, servo signal demodulation errors do not continuously occur due to the servo channel frequency setting of the read channel.

  When on-track at the boundary between servo signal pattern areas written at two different servo signal frequencies, provide an area to place two servo signal patterns at the servo signal frequencies used in the two areas Since servo signal patterns written at two different servo signal frequencies are arranged continuously in the circumferential direction, the read / write head does not read two servo signals with different servo signal frequencies at the same time. A servo signal with one servo frequency can be read.

  Since the servo signal frequency of the read channel is set to one of the two servo signal frequencies, it is possible to demodulate the servo signal. No demodulation error will occur.

  FIG. 20 is a layout diagram of servo signal patterns in the third embodiment of the present invention. Here, however, the state of the servo signal pattern formed on the servo cylinder 20 of the single disk 10 is shown as a representative.

  In the third embodiment of FIG. 20, recording is performed by changing the recording density of the servo signal pattern on the disk in the area where the servo signal is written on the disk surface. Here, the area from the inner side to the outer side of the disk 10 in the servo cylinder 20 is divided into several areas (for example, P0, P1).

  Different servo signal frequencies Fs0 and Fs1 are set for each of the divided servo cylinder regions, and servo signal patterns corresponding to the set servo signal frequencies are respectively arranged.

  On the other hand, the servo signal frequency is set so that the error rate characteristic of the servo sync mark, the error rate characteristic of the gray code, and the dispersion characteristic of the burst value are relatively good.

  Further, a servo signal pattern region P0 in which the servo signal frequency is set to Fs0, and a servo signal pattern region P1 in which the servo signal frequency adjacent to the servo signal pattern region P0 in which the servo signal frequency is set to Fs0 is set to Fs1. A region P01 in which servo signal patterns with servo signal frequencies set to Fs0 and Fs1 are arranged in the same servo cylinder is provided at the boundary.

  In the region P01 where the servo signal patterns whose servo signal frequencies are set to Fs0 and Fs1 are arranged in the same servo cylinder, the interval is half the interval between the servo signal patterns arranged in the adjacent servo signal frequency regions. Servo signal patterns are arranged accordingly. Here, servo signal patterns of servo signal frequencies Fs0 and Fs1 are alternately arranged for each servo signal pattern on the servo cylinder.

  On the other hand, the servo signal pattern written with the same servo signal frequency is the same as the servo signal pattern in the servo signal frequency area even if the two servo signal pattern areas and the servo signal frequency area are different. Arrange the top and the phase.

  In the embedded servo system, since the servo signal pattern is arranged across the data area, it is necessary to estimate the position of the read / write head until the next servo signal pattern is read during the seek operation of the read / write head. .

  In the area where servo signal patterns written at two servo signal frequencies exist, the width of the servo cylinder is twice as large as the maximum position estimation error when estimating the position of the read / write head. .

  21 to 23 are first to third flowcharts for explaining the seek operation in the third embodiment of the present invention, respectively.

  First, as shown in step S60, when a seek command is issued, the position of the read / write head in the next servo signal pattern is determined from the servo information, VCM current, etc. regarding the accumulated read / write head position. Is estimated (step S61).

  The correspondence table between the servo cylinder and the area is compared with the estimated read / write head position, and the area to which the estimated read / write head position belongs is determined (step S62).

  Furthermore, the estimated position of the read / write head is an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area (step S63 in FIG. 21). In addition, the estimated read / write head position is on the outer side of the disk from the servo cylinder at the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is located. If so (step S64 in FIG. 22), before reading the next servo signal pattern, the servo signal frequency of the read channel is the servo signal written at the two servo signal frequencies to which the estimated read / write head position belongs. Set for the servo signal frequency area that touches the outer side of the area where the pattern exists Set to turbo signal frequency (step S65 in FIG. 22).

  On the other hand, the estimated read / write head position is an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area (step S63 in FIG. 21). ) And the estimated read / write head position is higher than the servo cylinder at the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is present. If it is on the inner side (step S64 in FIG. 22), before reading the next servo signal pattern, the servo signal frequency of the read channel is written with the two servo signal frequencies to which the estimated read / write head position belongs. Set for the servo signal frequency area that touches the inner side of the area where the servo signal pattern exists. Set to a servo signal frequency (step S66 in FIG. 22).

  On the other hand, when the estimated read / write head position is not a region where there is a servo signal pattern newly written at two servo signal frequencies arranged at the boundary of the servo signal frequency region (step in FIG. 21). S63) When the estimated position of the read / write head belongs to an area different from the servo signal frequency area to which the latest (to date) position belongs (step S70 in FIG. 22), the next servo signal pattern Before reading, the servo signal frequency of the read channel is set to the servo signal frequency in the servo signal frequency region to which the estimated read / write head position belongs (step S71 in FIG. 22).

  On the other hand, when the estimated read / write head position is not a region where there is a servo signal pattern newly written at two servo signal frequencies arranged at the boundary of the servo signal frequency region (step in FIG. 21). S63) When the estimated position of the read / write head belongs to the same area as the servo signal frequency area to which the latest (to date) position belongs (step S70 in FIG. 22), the servo signal of the read channel The frequency setting is not changed (step S73 in FIG. 22).

  Further, when the estimated read / write head position is an area where a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area exists, the estimated read / write head Within the servo cylinder range for the head position estimation error centered on the servo cylinder at the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is located If there is (step S67 in FIG. 22), the timing for reading (reading) the servo signal pattern is set to an interval that is half the timing in the servo signal pattern area written at a single servo signal frequency ( Step S68 in FIG.

  On the other hand, if the estimated read / write head position is an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area, Servo cylinder range for the head position estimation error centered on the servo cylinder at the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is located If it is outside (step S67 in FIG. 22), a single servo signal frequency that is in contact with an area where servo signal patterns written at two servo signal frequencies closest to the estimated read / write head position are present. Is set to the timing for reading the servo signal pattern in the servo signal pattern area written in FIG. Step S69 of).

  Furthermore, the estimated read / write head position is not a region where there is a servo signal pattern newly written at two servo signal frequencies arranged at the boundary of the servo signal frequency region (step S63 in FIG. 21). When the estimated read / write head position belongs to an area different from the servo signal frequency area to which the latest (to date) position belongs (step S70 in FIG. 22), the servo signal pattern is read (read). The timing is set to the timing of the servo pattern area written at the single servo signal frequency to which the estimated read / write head position belongs (step S72 in FIG. 22).

  Furthermore, the estimated read / write head position is not a region where there is a servo signal pattern newly written at two servo signal frequencies arranged at the boundary of the servo signal frequency region (step S63 in FIG. 21). When the estimated read / write head position belongs to the same area as the servo signal frequency area to which the latest (to date) position belongs (step S70 in FIG. 22), the timing for reading the servo signal pattern is No change is made (step S74 in FIG. 22).

  Further, as shown in step S75 of FIG. 23, the next servo signal pattern is read and the servo signal is demodulated.

  If the servo signal cannot be demodulated (due to a servo sync mark detection error) (step S76 in FIG. 23), head positioning is executed using the estimated read / write head position (FIG. 23). Step S77).

  On the other hand, when the servo demodulation can be performed (because the servo sync mark is detected normally) (step S76 in FIG. 23), the demodulated positioning information is stored in the memory, and the newly obtained positioning information is stored. Using this, head positioning is executed (step S78 in FIG. 23).

  If the position of the read / write head is a seek-purpose servo cylinder (step S79 in FIG. 23), the seek operation is terminated (step S80 in FIG. 23). Estimate the position of the read / write head when reading the servo signal pattern.

  Next, the effect of the third embodiment of the present invention will be described. According to the third embodiment, as a result of estimating the position of the read / write head when reading the next servo signal pattern during the seek operation of the read / write head, the estimated position of the read / write head is: When the boundary between the servo signal frequency area and the servo signal frequency area, that is, the servo signal pattern written at the two newly provided servo signal frequencies is located on the same servo cylinder Even if the estimated read / write head position contains an estimation error and the estimated read / write head position is different from the actual position where the read / write head arrives, the two newly provided servo signals The area where servo signal patterns written in frequency are arranged on the same servo cylinder has twice as many cylinders as the estimation error. It has become way.

  Therefore, by setting the servo signal frequency of the read channel to one of the servo signal frequencies, the servo signal pattern of two different servo signal frequencies arranged alternately on the servo cylinder is reduced to 1/2. The servo signal can be demodulated with probability.

  On the other hand, even during a low-speed seek operation, the estimated lead is read when the servo signal pattern written with two newly provided servo signal frequencies passes near the area arranged on the same servo cylinder.・ Estimated error is included in the position of the write head, and even if the servo signal frequency of the read channel is different from the servo signal frequency of the read servo signal and the servo signal cannot be demodulated, The servo signal frequency is the servo signal frequency set to the read channel servo signal frequency, and since the servo signal can be demodulated, it prevents the seek error that some servo signals cannot be demodulated continuously. Is possible.

  Furthermore, in the area where servo signal patterns written at two different servo signal frequencies are arranged on the same servo cylinder, servo signal patterns of two different servo signal frequencies are alternately arranged at 1/2 time intervals. Therefore, even if the servo signal cannot be demodulated once due to the frequency setting factor, the servo signal can be demodulated in a short time, and the positioning accuracy can be improved.

  FIG. 24 is a layout diagram of servo signal patterns in the fourth embodiment of the present invention. Here, however, the state of the servo signal pattern formed on the servo cylinder 20 of the single disk 10 is shown as a representative.

  In the fourth embodiment of FIG. 24, recording is performed by changing the recording density of the servo signal pattern on the disk in the area where the servo signal is written on the disk surface. Here, in the servo cylinder 20, the area from the inner side to the outer side of the disk 10 is divided into four areas (P0, P1, P2, and P3).

  Different basic servo signal frequencies Fs0, Fs1, Fs2, and Fs3 are set for each of the divided servo cylinder regions.

  On the other hand, the servo signal frequency is set so that the error rate characteristic of the servo sync mark, the error rate characteristic of the gray code, and the dispersion characteristic of the burst value are relatively good.

  Here, the width of the servo signal area in which one servo signal frequency is written is set larger than the number of servo cylinders corresponding to the maximum estimated error of the head position estimating means of the read / write head.

  Furthermore, in the servo signal frequency area on the outer side of the disk than the servo cylinder in the center of the servo signal frequency area, the servo signal pattern written at the basic servo signal frequency and the outer side of the servo signal frequency area. Servo signal patterns written at the servo signal frequency in the adjacent servo signal frequency region are continuously arranged without any interval.

  Furthermore, in the servo signal frequency area on the inner side of the disk than the servo cylinder at the center of the servo signal frequency area, the servo signal pattern written at the basic servo signal frequency and the inner side of the servo signal frequency area. Servo signal patterns written at the servo signal frequency in the adjacent servo signal frequency region are continuously arranged without any interval.

  Servo signal patterns written at the same servo signal frequency are arranged with the same phase as the head portion even if the servo signal frequency regions are different in adjacent servo signal frequency regions. On the other hand, when the read / write head is on-tracked at the boundary between adjacent servo signal frequency areas, the servo signal patterns with different servo signal frequencies are not read at the same time. .

  FIGS. 25 to 27 are first to third flowcharts for explaining the seek operation in the fourth embodiment of the present invention, respectively.

  First, as shown in step S90, when a seek command is issued, the position of the read / write head in the next servo signal pattern is determined from the servo information, VCM current, etc. regarding the accumulated read / write head position. Is estimated (step S91).

  The correspondence table between the servo cylinder and the area is compared with the estimated read / write head position to determine the area to which the estimated read / write head position belongs (step S92).

  Further, the estimated read / write head position is located on the outer side of the disk from the servo cylinder at the center of the area where the servo signal patterns written at the two servo signal frequencies to which the estimated read / write head position belongs are present. If so (step S93 in FIG. 25), before reading the next servo signal pattern, the servo signal frequency of the read channel is the servo signal written at the two servo signal frequencies to which the estimated read / write head position belongs. The servo signal frequency set for the servo signal frequency region in contact with the outer side of the region where the pattern exists is set (step S94 in FIG. 26).

  On the other hand, the estimated read / write head position is larger than the servo cylinder at the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is located. If it is on the inner side (step S93 in FIG. 25), before reading the next servo signal pattern, the servo signal frequency of the read channel is written with the two servo signal frequencies to which the estimated read / write head position belongs. The servo signal frequency set for the servo signal frequency region in contact with the inner side of the region where the servo signal pattern exists is set (step S95 in FIG. 26).

  Further, as shown in step S96 of FIG. 26, two servo signals read (read) successively are demodulated. Here, since the servo signal frequency of the read channel is set to one of the two servo signals, the servo signal can always be demodulated for either one of the two servo signals. (Steps S97 to S100 in FIG. 26).

  Of the two servo signal demodulation results, head positioning is executed using the positioning information that can be demodulated (because servo sync mark detection has been performed normally) (step S102 in FIG. 27).

  On the other hand, when demodulation cannot be performed (due to a servo sync mark detection error), head positioning is executed using the estimated read / write head position (step S101 in FIG. 27).

  If the position of the read / write head is a seek-purpose servo cylinder (step S103 in FIG. 27), the seek operation is terminated (step S104 in FIG. 27). The position of the read / write head when the servo signal pattern is read is estimated and the seek operation is repeated.

  When the servo cylinder in the on-track state is an area where servo signal patterns written with the servo signal frequencies Fs0 and Fs1 exist, the two servo signal frequencies arranged in succession as in the seek operation Servo signal patterns with different values are read continuously to demodulate servo signals.

  Since the servo signal frequency of the read channel is set to either Fs0 or Fs1, the servo signal written at either one of the servo signal frequencies (Fs0 or Fs1) can be demodulated. Is possible. Head positioning can be performed using the result of demodulating the servo signal.

  Next, the effect of the fourth embodiment of the present invention will be described. According to the fourth embodiment, as a result of estimating the position of the read / write head when reading the next servo signal pattern during the seek operation of the read / write head, the estimated position of the read / write head is: When it is near the boundary between the servo signal frequency area and the servo signal frequency area, the servo signal frequency area to which the estimated read / write head position belongs and the servo signal to which the actual read / write head position belongs Even if the frequency region is different, the two servo signal frequency regions are adjacent to each other. Therefore, up to half of the two servo signal frequency areas, servo signal patterns of the basic servo signal frequency of each other are arranged, so two servo signal patterns arranged in succession are read and servo signals are read. If the servo signal is demodulated, the servo signal in which one of the servo signal frequencies is written can be demodulated, so that a servo signal demodulation error does not occur due to the servo channel frequency setting of the read channel.

  On the other hand, even during a low-speed seek operation, it is possible to prevent servo signal demodulation errors from occurring continuously due to the servo channel frequency setting of the read channel.

  In addition, when on-track at the boundary between servo signal pattern areas written at two different servo signal frequencies, the area where two servo signal patterns of servo signal frequencies used in the two areas are placed Since servo signal patterns written at two different servo signal frequencies are arranged continuously in the circumferential direction, the read / write head does not read two servo signals with different servo signal frequencies at the same time. The servo signal of a single servo frequency can be read.

  Further, since the servo signal frequency of the read channel is set to one of the two servo signal frequencies, it is possible to demodulate the servo signal. It is possible to prevent a servo signal demodulation error from occurring.

  FIG. 28 is a layout diagram of servo signal patterns in the fifth embodiment of the present invention. Here, however, the state of the servo signal pattern formed on the servo cylinder 20 of the single disk 10 is shown as a representative.

  In the fifth embodiment of FIG. 28, recording is performed by changing the recording density of the servo signal pattern on the disk in the area where the servo signal is written on the disk surface. Here, in the servo cylinder 20, the area from the inner side to the outer side of the disk 10 is divided into two areas (PC0, PC1).

  Different central servo signal frequencies Fs0 and Fs1 are set for each of the divided servo cylinder regions, and servo signal patterns corresponding to the set central servo signal frequencies are respectively arranged.

  Further, for each servo cylinder, the servo signal frequency within the servo signal frequency follow-up range of the frequency dividing circuit in the servo PLL circuit of the read channel (for example, the servo PLL circuit included in the read channel 25 of FIG. 9) from the central servo signal frequency. The servo signal pattern is arranged by changing. In this case, the recording density of the servo signal pattern was set so that the error rate characteristic of the servo sync mark, the error rate characteristic of the gray code, and the dispersion characteristic of the burst value were in a relatively good range, and was set for each area. Servo signal patterns with different servo signal frequencies are arranged for each servo cylinder with the center servo signal frequency at the center.

  Further, the servo signal pattern area PC0 with the center servo signal frequency set to Fs0 and the servo signal pattern area PC0 with the center servo signal frequency set to Fs0 and the center servo signal frequency set to Fs1 are set to Fs1. A region PC01 in which servo signal patterns whose central servo signal frequencies are set to Fs0 and Fs1 are arranged in the same servo cylinder is provided at the boundary with the signal pattern region PC1.

  Here, in the area PC01 in which the servo signal patterns whose center servo signal frequencies are set to Fs0 and Fs1 are arranged in the same servo cylinder, the servo signal centered on the servo signal frequency Fs0 for each servo signal pattern. The servo signal pattern set to the frequency and the servo signal pattern set to the servo signal frequency centered on the servo signal frequency Fs1 are alternately arranged.

  In the embedded servo system, since the servo signal pattern is arranged across the data area, it is necessary to estimate the position of the read / write head until the next servo signal pattern is read during the seek operation of the read / write head. .

  In the area where servo signal patterns written at two servo signal frequencies exist, the width of the servo cylinder is twice as large as the maximum position estimation error when estimating the position of the read / write head. .

  FIGS. 29 to 31 are first to third flowcharts for explaining the seek operation in the fifth embodiment of the present invention, respectively.

  First, as shown in step S110, when a seek command is issued, the position of the read / write head in the next servo signal pattern is determined from the servo information, VCM current, etc. regarding the accumulated read / write head position. Is estimated (step S111).

  The correspondence table between the servo cylinder and the area is compared with the estimated read / write head position to determine the area to which the estimated read / write head position belongs (step S112).

  Furthermore, the estimated read / write head position is an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area (step S113 in FIG. 29). In addition, the estimated read / write head position is on the outer side of the disk from the servo cylinder at the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is located. If so (step S114 in FIG. 30), before reading the next servo signal pattern, read the servo signal frequency of the read channel with the servo signal written at the two servo signal frequencies to which the estimated read / write head position belongs. Set for the servo signal frequency area that touches the outer side of the area where the pattern exists. Setting the servo signal frequency that (step S115 in FIG. 30).

  On the other hand, the estimated read / write head position is an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area (step S113 in FIG. 29). ) And the estimated read / write head position is higher than the servo cylinder at the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is present. If it is on the inner side (step S114 in FIG. 30), before reading the next servo signal pattern, the servo signal frequency of the read channel is written with the two servo signal frequencies to which the estimated read / write head position belongs. Set for the servo signal frequency area that touches the inner side of the area where the servo signal pattern exists. Was set to the servo signal frequency are (step S116 in FIG. 30).

  On the other hand, when the estimated read / write head position is not an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area (step of FIG. 29). S113) When the estimated read / write head position belongs to an area different from the servo signal frequency area to which the latest (to date) position belongs (step S117 in FIG. 30), the next servo signal pattern Before reading, the servo signal frequency of the read channel is set to the servo signal frequency in the servo signal frequency region to which the estimated read / write head position belongs (step S118 in FIG. 30).

  On the other hand, when the estimated read / write head position is not an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area (step of FIG. 29). S113) When the estimated read / write head position belongs to the same area as the servo signal frequency area to which the latest (to date) position belongs (step S117 in FIG. 30), the servo signal of the read channel The frequency setting is not changed (step S119 in FIG. 30).

  Further, as shown in step S120 of FIG. 31, the next servo signal pattern is read and the servo signal is demodulated.

  Here, the servo signal frequency is changed for each servo cylinder, but it is within the servo signal frequency tracking range of the frequency dividing circuit in the servo PLL circuit of the read channel, so that it can follow the servo signal frequency of the servo signal. The servo signal can be demodulated.

  When the servo signal cannot be demodulated (due to a servo sync mark detection error) (step S121 in FIG. 31), head positioning is executed using the estimated read / write head position (step S123 in FIG. 31). .

  On the other hand, when the servo demodulation can be performed (because servo sync mark detection has been performed normally) (step S121 in FIG. 31), the demodulated positioning information is stored in the memory, and the newly obtained positioning information is stored. Then, the head positioning is executed (step S122 in FIG. 31).

  If the position of the read / write head is a seek-purpose servo cylinder (step S124 in FIG. 31), the seek operation is terminated (step S125 in FIG. 31). Estimate the position of the read / write head when reading the servo signal pattern.

  FIG. 32 is a schematic diagram showing the estimated position of the read / write head in the fifth embodiment of the present invention. Based on this FIG. 32, the effect of the said 5th Example is demonstrated.

  According to the fifth embodiment, as a result of estimating the position of the read / write head when reading the next servo signal pattern during the seek operation of the read / write head, the estimated position of the read / write head is When the boundary between the signal frequency area and the servo signal frequency area, that is, the servo signal pattern written at the two newly provided servo signal frequencies is an area arranged on the same servo cylinder, Even if the estimated read / write head position contains an estimation error and the estimated read / write head position is different from the actual position where the read / write head arrives, the two newly provided servo signal frequencies The area where the servo signal pattern written in is located on the same servo cylinder has twice as many cylinders as the estimation error It has become the jar.

  Therefore, by setting the servo signal frequency of the read channel to one of the servo signal frequencies, the servo signal pattern of two different servo signal frequencies arranged alternately on the servo cylinder is reduced to 1/2. The servo signal can be demodulated with probability.

  On the other hand, even during a low-speed seek operation, the estimated lead is read when the servo signal pattern written with two newly provided servo signal frequencies passes near the area arranged on the same servo cylinder.・ Estimated error is included in the position of the write head, and even if the servo signal frequency of the read channel is different from the servo signal frequency of the read servo signal and the servo signal cannot be demodulated, The servo signal frequency is the servo signal frequency set to the read channel servo signal frequency, and since the servo signal can be demodulated, it prevents the seek error that some servo signals cannot be demodulated continuously. Is possible.

  Here, by changing the servo signal frequency for each servo cylinder, the recording density range of the servo signal pattern on the disk surface can be further narrowed, and the error rate characteristics of the servo sync mark and the error rate of the gray code It is possible to use the disk within a good range of characteristics and dispersion characteristics of burst values.

  FIG. 33 is a diagram showing a servo signal frequency range that can be pulled in the servo PLL circuit that cannot be used in the fifth embodiment of the present invention, and FIG. 34 is a servo PLL circuit used in the fifth embodiment of the present invention. It is a figure which shows the servo signal frequency range which can be drawn.

  With reference to FIGS. 33 and 34, the servo signal frequency range in which the servo PLL circuit can be pulled in when the servo signal frequency setting is changed for each servo cylinder in the fifth embodiment will be described in more detail. I decided to.

  In the fifth embodiment, when the servo signal pattern is arranged by changing the servo signal frequency for each servo cylinder from the central servo signal frequency set in each area of the servo signal frequency, the central servo signal It is desirable that the servo signal frequency range fluctuating from the frequency is not limited to the servo signal frequency tracking range of the servo PLL circuit. Conversely, the recording density of the servo signal pattern on the maximum outer diameter side and the minimum inner diameter side in the servo signal frequency area is compared with the error rate characteristics of the servo sync mark, the error rate characteristics of the Gray code, and the dispersion characteristics of the burst value. It is preferable to set so as to be within the desired range.

  As for the servo signal frequency that can be demodulated by the read channel, as shown in FIG. 33, the scale of the servo PLL circuit mounted in the disk device is limited, so that the discrete servo signal frequency (for example, Fsa, Fsb and Fsc) can only be set. Therefore, when the servo signal frequency is changed using the servo PLL circuit of the read channel, there is a servo signal frequency range that cannot be demodulated by the read channel (that is, a range in which the servo signal frequency cannot be followed). It will be.

  In order to cope with such an inconvenient situation, in FIG. 34, the servo signal is set so that the fluctuation ranges of a plurality of servo signal frequencies (for example, Fsa, Fsb, and Fsc) set by the servo PLL circuit of the read channel overlap. A frequency tracking range is set in advance. In this way, the servo signal frequency fluctuation range that can be followed by the servo PLL circuit overlaps in all servo signal frequency bands on the disk surface, and one servo signal set by the read channel servo PLL circuit. There is no servo signal frequency band that cannot be followed between the frequency and another servo signal frequency adjacent to the servo signal frequency.

  In other words, if the servo signal frequency has a wide range in one servo signal frequency region and the read channel is set for the central servo signal frequency set in each region, one servo signal frequency is set. Even if the signal frequency cannot be tracked, the servo signal frequency can be tracked by the servo PLL circuit by resetting the read channel for the servo signal frequency next to the center servo signal frequency. Can be demodulated without error.

  As a result, the recording density of the servo signal pattern on the maximum outer diameter side and the minimum inner diameter side in the servo signal frequency range in the wider servo signal frequency range, the error rate characteristics of the servo sync mark, the error rate characteristics of the Gray code, and the burst It becomes possible to set so that the dispersion characteristic of the value is in a relatively good range.

  FIG. 35 is a layout diagram of servo signal patterns in the sixth embodiment of the present invention. Here, however, the state of the servo signal pattern formed on the servo cylinder 20 of the single disk 10 is shown as a representative.

  In the sixth embodiment of FIG. 35, recording is performed by changing the recording density of the servo signal pattern on the disk surface in the area where the servo signal is written on the disk surface. Here, the servo cylinder 20 is divided into two regions (P0, P1) from the inner side to the outer side of the disk 10.

  Different servo signal frequencies Fs0 and Fs1 are set for each of the divided servo cylinder regions, and servo signal patterns of the set servo signal frequencies are respectively arranged.

  In this case, regarding the servo signal frequency at the center of each area, the recording density of the servo signal pattern on the maximum outer diameter side and the minimum inner diameter side of each area depends on the error rate characteristics of the servo sync mark and the error rate of the Gray code. Setting is made so that the characteristics and the dispersion characteristic of the burst value are in a relatively good range.

  Further, a servo signal pattern region P0 in which the servo signal frequency is set to Fs0, and a servo signal pattern region P1 in which the servo signal frequency adjacent to the servo signal pattern region P0 in which the servo signal frequency is set to Fs0 is set to Fs1. A region P01 in which servo signal patterns whose center servo signal frequencies are set to Fs0 and Fs1 are arranged in the same servo cylinder is provided at the boundary of.

  The servo signal pattern written at the servo signal frequency Fs0 and the servo signal pattern written at the servo signal frequency Fs1 are arranged on the same servo cylinder. In the region P01 where two servo signal patterns exist, different servo signal frequencies. Servo signal patterns having two different servo signal frequencies are arranged continuously in the circumferential direction of the disk so as not to be read simultaneously by the read / write head.

  On the other hand, even if the two servo signal patterns exist and the servo signal frequency area is different, the servo signal pattern written with the same servo signal frequency will be placed in the servo signal frequency area. Arrange the signal pattern head and phase so that they are aligned.

  In the embedded servo system, the servo signal pattern is placed across the data area. Therefore, when the read / write head seeks, the next servo signal pattern is read until the next servo signal pattern is read. It is necessary to estimate the position of the head, and this read / write head position estimation error must be considered. In the area where the servo signal pattern written at the servo signal frequency Fs0 and the servo signal pattern written at the servo signal frequency Fs1 are arranged on the same servo cylinder, the maximum position estimation error when estimating the position of the read / write head The width of the servo cylinder is twice as large as that of the servo cylinder.

  Here, in addition to the servo signal pattern for changing the servo signal frequency from the inner side to the outer side of the disk 10, a servo signal pattern written at a single servo signal frequency Fs2 from the inner side to the outer side of the disk 10 is also used. Are arranged in one place on the servo cylinder (for example, the region PS2).

  36 to 38 are flowcharts 1 to 3 for explaining the seek operation in the sixth embodiment of the present invention, respectively.

  First, as shown in step S130, when a seek command is issued, the position of the read / write head in the next servo signal pattern is determined from the servo information related to the read / write head position accumulated, the VCM current, and the like. Is estimated (step S131).

  The correspondence table between the servo cylinder and the area is compared with the estimated read / write head position, and the area to which the estimated read / write head position belongs is determined (step S132).

  Further, the estimated read / write head position is an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area (step S133 in FIG. 36). In addition, the estimated read / write head position is on the outer side of the disk from the servo cylinder at the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is located. If so (step S134 in FIG. 37), before reading the next servo signal pattern, the servo signal frequency of the read channel is the servo signal written at the two servo signal frequencies to which the estimated read / write head position belongs. Set for the servo signal frequency area that touches the outer side of the area where the pattern exists. Setting the servo signal frequency that (step S135 in FIG. 37).

  On the other hand, the estimated read / write head position is an area where there is a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area (step S133 in FIG. 36). ) And the estimated read / write head position is higher than the servo cylinder at the center of the area where the servo signal pattern written at the two servo signal frequencies to which the estimated read / write head position belongs is present. If it is the inner side (step S134 in FIG. 37), before reading the next servo signal pattern, the servo signal frequency of the read channel is written with the two servo signal frequencies to which the estimated read / write head position belongs. Set for the servo signal frequency area that touches the inner side of the area where the servo signal pattern exists And Aru set to the servo signal frequency (step S136 in FIG. 37)).

  On the other hand, when the estimated read / write head position is not an area where there is a servo signal pattern newly written at two servo signal frequencies arranged at the boundary of the servo signal frequency area (step in FIG. 36). S133) When the estimated position of the read / write head belongs to an area different from the servo signal frequency area to which the latest (to date) position belongs (step S138 in FIG. 37), the next servo signal pattern Before reading, the servo signal frequency of the read channel is set to the servo signal frequency in the servo signal frequency region to which the estimated read / write head position belongs (step S139 in FIG. 37).

  On the other hand, when the estimated read / write head position is not an area where there is a servo signal pattern newly written at two servo signal frequencies arranged at the boundary of the servo signal frequency area (step in FIG. 36). S133) When the estimated read / write head position belongs to the same area as the servo signal frequency area to which the latest (to date) position belongs (step S138 in FIG. 37), the servo signal of the read channel The frequency setting is not changed (step S140 in FIG. 37).

  Further, when the estimated position of the read / write head is an area where a servo signal pattern written at two servo signal frequencies newly arranged at the boundary of the servo signal frequency area exists, it is continuously read ( The two servo signals to be read are demodulated (step S137 in FIG. 37).

  Since the servo signal frequency of the read channel is set to one of two different servo signals, the servo signal can always be demodulated with respect to one of the two servo signals (FIG. 37). Steps S142 and S143, and Steps S144 and S145 in FIG. 38).

  Of the two servo signal demodulation results, head positioning is executed using the positioning information of the one that could be demodulated (because the servo sync mark was normally detected) (step S151 in FIG. 38).

  If the estimated read / write head position is not an area where there is a servo signal pattern written with two servo signal frequencies newly placed at the boundary of the servo signal frequency area, the next servo signal pattern is read. Servo demodulation is executed (step S141 in FIG. 37).

  Here, when the servo signal cannot be demodulated (due to a servo sync mark detection error) (step S146 in FIG. 38), if the servo signal demodulation error does not occur continuously more than the number of seek error determinations (FIG. 38, step S148), head positioning is executed using the estimated read / write head position (step S151 in FIG. 38).

  On the other hand, when the servo demodulation can be performed (because the servo sync mark is normally detected) (step S146 in FIG. 38), the demodulated positioning information is stored in the memory (step S147 in FIG. 38). Head positioning is executed using the newly obtained positioning information (step S152 in FIG. 38).

  If the position of the read / write head is a seek-purpose servo cylinder (step S153 in FIG. 38), the seek operation is terminated (step S154 in FIG. 38). Estimate the position of the read / write head when reading the servo signal pattern and repeat the seek operation.

  On the other hand, if a servo signal demodulation error occurs continuously more than the number of seek error determinations and the servo signal cannot be demodulated (step S148 in FIG. 38), a servo signal frequency setting error has occurred. In order to read and read the servo signal pattern written with a single servo signal frequency from the inner side to the outer side of the disk, the servo signal frequency of the read channel is changed with the single servo signal frequency from the inner side to the outer side. The servo signal frequency (Fs2) of the written servo signal pattern is set (step S149 in FIG. 38).

  In addition, read the servo signal pattern written at a single servo signal frequency located on the servo cylinder from the inner side to the outer side of the disk to recover the position information of the read / write head. (Step S150 in FIG. 38). Here, the servo frequency of the read channel is set again so that the servo signal frequency corresponding to the position of the read / write head is obtained, and the seek operation is continued.

  Next, the effect of the sixth embodiment of the present invention will be described. If the read / write head position suddenly shifts greatly due to external force, the read / write head position moves to a different servo signal frequency area, and the servo set in the read channel The servo signal may not be demodulated because the signal frequency and the servo signal frequency of the servo signal actually read from the read / write head are significantly different.

  If a seek error occurs during a seek operation, once the read / write head can be moved without positioning information and the servo signal frequency is known, such as the servo cylinder position on the minimum inner diameter side, The write head must be moved and the read / write head positioned again.

  In the sixth embodiment, a plurality of servo cylinders from the inner side to the outer side are written at a single servo signal frequency from the inner side to the outer side in addition to the servo signal pattern for changing the servo signal frequency. One servo signal pattern is arranged.

In this way, even if the servo signal frequency set in the read channel is different from the servo signal frequency of the servo signal to be read, the servo signal frequency of the read channel is set regardless of the servo signal frequency area. By setting the servo signal frequency of a servo signal pattern written at a single servo signal frequency, position information can be recovered from the servo signal pattern written at a single servo signal frequency. Therefore, the servo signal frequency of the area to which the read / write head position belongs can be set again without moving to a specific servo cylinder such as a servo cylinder on the minimum inner diameter side. It is possible to reset the frequency in a short time.

  The disk mounted on the disk device applied to the first to sixth embodiments described above may be removable from the disk device, such as when used as a single plate STW. The disk in this case can be shipped as a disk medium independent from the disk device with the servo signal pattern used in the first to sixth embodiments written in the servo cylinder.

(Supplementary note 1) A plurality of servo cylinders formed concentrically from the inner diameter part to the outer diameter part of the disk are divided into predetermined areas, and different servo signal frequencies are set for each divided area. In the disk device, the servo signal pattern corresponding to each servo signal frequency set for each region is arranged, and the servo signal frequency set for each region is stored in advance.
The recording density of the servo signals recorded on the disk is set so that the demodulation characteristics of the servo signals are in a relatively good range, the plurality of servo cylinders are divided into predetermined areas and the areas are A disk device configured to set a servo signal frequency.

(Supplementary note 2) Servo cylinders formed concentrically from the inner diameter part to the outer diameter part of the disk are divided into predetermined areas, and different servo signal frequencies are set for the divided areas. In the disk device in which the servo signal pattern of the frequency of the servo signal set for each region is arranged and the servo signal frequency set for each region is stored,
At the boundary between the divided first servo signal frequency region and the second servo signal frequency region adjacent to the first servo signal frequency region, the servo signal frequency in the first servo signal frequency region is the boundary. 2. A disk device comprising: an area in which a written servo signal pattern and a servo signal pattern written at a servo signal frequency in the second servo signal frequency area are arranged on the same servo cylinder.

  (Additional remark 3) The head used when performing the seek operation of the read / write head based on the number of servo cylinders in the area where servo signal patterns written at two different servo signal frequencies are arranged on the same servo cylinder The disk apparatus according to appendix 2, wherein the number of servo cylinders is equal to or greater than the maximum estimated error of the estimated position of the read / write head in the position estimating means.

  (Supplementary note 4) Servo signal pattern arranged in the area where servo signal pattern arranged in servo signal frequency area and servo signal pattern written in two different servo signal frequencies are arranged on the same servo cylinder The disk device according to claim 2, wherein servo signal patterns having the same servo signal frequency are arranged in phase at the head of the servo signal pattern.

  (Appendix 5) In the area where servo signal patterns written at two different servo signal frequencies are arranged on the same servo cylinder, the same servo positioning information was written at the servo signal frequency in the servo signal frequency area on both sides. The disk device according to appendix 2, wherein two servo signal patterns are arranged in succession.

  (Additional remark 6) The servo signal obtained by reading the two servo signal patterns with which the frequency arrange | positioned continuously differs can be demodulated continuously, and the servo positioning information of the servo signal pattern can be demodulated The disk apparatus according to appendix 5, wherein head positioning of the read / write head is performed using a demodulation result obtained.

(Appendix 7) When the read / write head performs a seek operation,
Next, estimate the position of the read / write head when reading the servo signal pattern,
If the servo cylinder corresponding to the estimated read / write head position is an area where servo signal patterns written at two different servo signal frequencies are arranged on the same servo cylinder, two different servos are used. Of the servo signal frequency area adjacent to the area where the servo signal pattern written at the signal frequency is located on the same servo cylinder, it is separated from the area to which the read / write head position that last demodulated the servo positioning information belongs. Set the servo signal frequency in the servo signal frequency area
On the other hand, if the servo cylinder corresponding to the estimated read / write head position is the same area as the read / write head position where the servo positioning information was last demodulated, the current servo signal frequency The servo signal frequency is set in the servo signal frequency region to which the servo cylinder corresponding to the estimated read / write head position belongs if the region is different. 2. The disk device according to 2.

(Appendix 8) When the read / write head performs a seek operation,
Next, estimate the position of the read / write head when reading the servo signal pattern,
If the servo cylinder corresponding to the estimated read / write head position is an area where servo signal patterns written at two different servo signal frequencies are arranged on the same servo cylinder, two different servos are used. Among servo signal frequency areas adjacent to the area where servo signal patterns written at the signal frequency are located on the same servo cylinder, the servo near the servo cylinder corresponding to the estimated read / write head position Set the servo signal frequency in the signal frequency area,
If the servo cylinder corresponding to the estimated read / write head position is the same area as the read / write head position where the servo positioning information was last demodulated, the current servo signal frequency is set. The disk according to appendix 2, wherein the servo signal frequency is set in the servo signal frequency region to which the servo cylinder corresponding to the estimated position of the read / write head belongs if the region is different. apparatus.

  (Supplementary note 9) In a region where servo signal patterns written at two different servo signal frequencies are arranged on the same servo cylinder, the same servo positioning information is used at two servo signal frequencies in the adjacent servo signal frequency region. 2. The disk device according to appendix 2, wherein two servo signal patterns in which are written are alternately arranged on the servo cylinder for each servo signal pattern.

(Supplementary Note 10) Servo cylinders that are concentrically formed from the inner diameter part to the outer diameter part of the disk are divided into several areas, and different servo signal frequencies are set for each of the divided areas. In the disk device in which servo signal patterns corresponding to the servo signal frequencies set for each region are arranged and the servo signal frequencies set for each region are stored in advance,
A servo signal pattern written at a servo signal frequency set in the first servo signal frequency region and a second servo adjacent to the first servo signal frequency region in the first servo signal frequency region Servo signal patterns written at the servo signal frequency set in the signal frequency region or the third servo signal frequency region adjacent to the first servo signal frequency region are arranged on the same servo cylinder. A disk device characterized by the above.

(Supplementary note 11) Servo cylinders that are concentrically formed from the inner diameter part to the outer diameter part of the disk are divided into several areas, and the center servo signal frequency is set for each divided area. In the disk device, the servo signal pattern corresponding to the center servo signal frequency set for each area is arranged, and the center servo signal frequency set for each area is stored in advance.
The servo signal recording density recorded on the disk is set so that each servo is centered on a central servo signal frequency set for each region so that the demodulation characteristic of the servo signal falls within a relatively good range. A disk device, wherein a servo signal pattern in which the servo signal frequency is changed is arranged for each cylinder.

  (Supplementary Note 12) The frequency range that can be recovered by frequency tracking around the servo signal frequency discretely set by the setting of the frequency divider of the servo PLL circuit is vacant by the setting of the servo signal frequency. The disk device according to appendix 11, wherein the frequency band can be continuously covered without creating a frequency band.

  (Supplementary note 13) The maximum range of the servo signal frequency to be changed in the servo signal frequency range is a range that can be recovered by following the servo signal frequency of the servo PLL circuit. Disk unit.

  (Supplementary note 14) Servo cylinders formed concentrically from the inner diameter part to the outer diameter part of the disk are divided into several areas, and different servo signal frequencies are set for each divided area. In each area, A servo signal pattern of the servo signal frequency set for each area is arranged, and a servo signal pattern written at a single servo signal frequency is arranged on the same servo cylinder from the inner diameter portion to the outer diameter portion of the disk. A disk device characterized by the above.

(Supplementary note 15) A plurality of servo cylinders formed concentrically from the inner diameter part to the outer diameter part of the disk surface are divided into predetermined areas, and different servo signal frequencies are set for the divided areas. In the disk medium in which the servo signal pattern of the frequency of the servo signal set for each area is arranged,
The recording density of the servo signal recorded on the disk surface is set so that the demodulation characteristic of the servo signal falls within a relatively good range, and the plurality of servo cylinders are divided into predetermined areas and for each area. A disk medium characterized in that the frequency of the servo signal is set.

(Supplementary Note 16) A plurality of servo cylinders formed concentrically from the inner diameter portion to the outer diameter portion of the disk surface are divided into predetermined areas, and different servo signal frequencies are set for each divided area. In the disk medium in which the servo signal pattern of the frequency of the servo signal set for each area is arranged,
At the boundary between the divided first servo signal frequency region and the second servo signal frequency region adjacent to the first servo signal frequency region, the servo signal frequency in the first servo signal frequency region is the boundary. A disk medium characterized in that an area in which a written servo signal pattern and a servo signal pattern written at a servo signal frequency in the second servo signal frequency area are arranged on the same servo cylinder is provided.

  (Supplementary Note 17) The number of servo cylinders in a region where servo signal patterns written at two different servo signal frequencies are arranged on the same servo cylinder is determined by the read operation when the read / write head seek operation is performed. The disk medium according to appendix 16, wherein the number of servo cylinders is equal to or greater than the maximum estimated error of the estimated position of the write head.

  (Supplementary Note 18) Servo signal pattern arranged in the area where the servo signal pattern arranged in the servo signal frequency area and the servo signal pattern written in two different servo signal frequencies are arranged on the same servo cylinder 18. The disk medium according to appendix 16, wherein servo signal patterns having the same servo signal frequency are arranged in phase at the head of the servo signal pattern.

  (Supplementary Note 19) In the area where servo signal patterns written at two different servo signal frequencies are arranged on the same servo cylinder, the same servo positioning information was written at the servo signal frequency in the servo signal frequency area on both sides. The disk medium according to appendix 16, wherein two servo signal patterns are arranged in succession.

  (Supplementary note 20) In a region where servo signal patterns written at two different servo signal frequencies are arranged on the same servo cylinder, the same servo positioning information is used at two servo signal frequencies in the adjacent servo signal frequency region. 18. The disk medium according to appendix 16, wherein two servo signal patterns in which are written are alternately arranged on the servo cylinder for each servo signal pattern.

(Supplementary note 21) A plurality of servo cylinders formed concentrically from the inner diameter part to the outer diameter part of the disk surface are divided into predetermined areas, and different servo signal frequencies are set for the divided areas. In the disk medium in which the servo signal pattern of the frequency of the servo signal set for each area is arranged,
A servo signal pattern written at a servo signal frequency set in the first servo signal frequency region and a second servo adjacent to the first servo signal frequency region in the first servo signal frequency region Servo signal patterns written at the servo signal frequency set in the signal frequency region or the third servo signal frequency region adjacent to the first servo signal frequency region are arranged on the same servo cylinder. A disk medium characterized by that.

(Supplementary note 22) In a disk medium in which a plurality of servo cylinders formed concentrically from an inner diameter part to an outer diameter part of a disk surface are divided into predetermined areas, and the frequency of a central servo signal is set for each divided area.
The servo signal recording density recorded on the disk is set so that each servo is centered on a central servo signal frequency set for each region so that the demodulation characteristic of the servo signal falls within a relatively good range. A disk medium comprising a servo signal pattern in which the servo signal frequency is changed for each cylinder.

  (Supplementary note 23) The disk medium according to supplementary note 22, wherein a maximum range of the servo signal frequency to be changed in the servo signal frequency range is a range that can be recovered by frequency tracking of the servo signal frequency.

  (Supplementary Note 24) Servo cylinders that are formed concentrically from the inner diameter part to the outer diameter part of the disk surface are divided into predetermined areas, and different servo signal frequencies are set for each divided area. In each area, A servo signal pattern of the servo signal frequency set for each area is arranged, and a servo signal pattern written at a single servo signal frequency is arranged on the same servo cylinder from the inner diameter portion to the outer diameter portion of the disk. A disk medium characterized by that.

It is a schematic diagram which shows the example of arrangement | positioning of a general servo signal pattern. It is a figure which shows the relationship between the magnetization reversal pattern of the servo signal recorded with the fixed servo signal frequency, and the reproduction | regeneration servo signal waveform. It is a graph which shows the mode of the change of the servo signal error rate with respect to a servo signal pattern density. It is a schematic diagram which shows the example of arrangement | positioning of the servo signal pattern using a prior art. It is a schematic diagram showing an example of the locus of the read / write head when an error is included in the estimated position of the read / write head in the conventional variable servo signal frequency method. It is a figure which shows the reproduction | regeneration servo signal waveform in the boundary of a different servo signal pattern in the conventional variable servo signal frequency system. It is a top view which shows schematic structure of the mechanism part of the disc apparatus based on the Example of this invention. It is a front view which shows schematic structure of the mechanism part of the disc apparatus based on the Example of this invention. It is a block diagram which shows the structure of the control part of the disk apparatus based on the Example of this invention. FIG. 3 is a layout diagram of servo signal patterns in the first embodiment of the present invention. It is a flowchart (the 1) for demonstrating the seek operation | movement in 1st Example of this invention. It is a flowchart (the 2) for demonstrating the seek operation | movement in 1st Example of this invention. It is a flowchart (the 3) for demonstrating the seek operation | movement in 1st Example of this invention. It is a schematic diagram which shows the estimated position of the read / write head in 1st Example of this invention. FIG. 6 is a layout diagram of servo signal patterns in a second embodiment of the present invention. It is a flowchart (the 1) for demonstrating the seek operation | movement in 2nd Example of this invention. It is a flowchart (the 2) for demonstrating the seek operation | movement in 2nd Example of this invention. It is a flowchart (the 3) for demonstrating the seek operation | movement in 2nd Example of this invention. It is a schematic diagram which shows the estimated position of the read / write head in 2nd Example of this invention. FIG. 10 is a layout diagram of servo signal patterns in a third embodiment of the present invention. It is a flowchart (the 1) for demonstrating the seek operation | movement in the 3rd Example of this invention. It is a flowchart (the 2) for demonstrating the seek operation | movement in 3rd Example of this invention. It is a flowchart (the 3) for demonstrating the seek operation | movement in 3rd Example of this invention. FIG. 10 is a layout diagram of servo signal patterns in a fourth embodiment of the present invention. It is a flowchart (the 1) for demonstrating the seek operation | movement in the 4th Example of this invention. It is a flowchart (the 2) for demonstrating the seek operation | movement in 4th Example of this invention. It is a flowchart (the 3) for demonstrating the seek operation | movement in the 4th Example of this invention. FIG. 10 is a layout diagram of servo signal patterns in a fifth embodiment of the present invention. It is a flowchart (the 1) for demonstrating the seek operation | movement in the 5th Example of this invention. It is a flowchart (the 2) for demonstrating the seek operation | movement in the 6th Example of this invention. It is a flowchart (the 3) for demonstrating the seek operation | movement in the 5th Example of this invention. It is a schematic diagram which shows the estimated position of the read / write head in the 5th Example of this invention. It is a figure which shows the servo signal frequency range which can be pulled in of the servo PLL circuit which cannot be used in the 5th Example of this invention. It is a figure which shows the servo signal frequency range which can be pulled in of the servo PLL circuit used in the 5th Example of this invention. FIG. 10 is a layout diagram of servo signal patterns in a sixth embodiment of the present invention. It is a flowchart (the 1) for demonstrating the seek operation | movement in the 6th Example of this invention. It is a flowchart (the 2) for demonstrating the seek operation | movement in the 6th Example of this invention. It is a flowchart (the 3) for demonstrating the seek operation | movement in the 6th Example of this invention.

Explanation of symbols

1 disk device 2 disk enclosure 3 printed circuit assembly 4 host system 10 disk 11 spindle 12 spindle motor 13 voice coil motor 14 arm 15 read / write head 16 lamp mechanism 17 head IC
20 Servo cylinder 21 Hard disk controller 22 RAM
23 Flash ROM
24 MPU
25 Read channel 26 Servo controller 27 Driver 28 Driver

Claims (2)

Servo cylinders that are concentrically formed from the inner diameter part to the outer diameter part of the disk are divided into several areas, and different servo signal frequencies are recorded and set for each divided area. In the disk device that arranges the servo signal pattern of the servo signal frequency set for each ,
A region where the servo signal frequency is set to the second servo signal frequency in a region where the servo signal frequency is set to the first servo signal frequency and a region adjacent to the region where the servo signal frequency is set to the first servo signal frequency The servo signal pattern written at the first servo signal frequency and the servo signal pattern written at the second servo signal frequency are arranged in the same servo cylinder at the boundary In the region, the servo signal patterns of the first servo signal frequency and the second servo signal frequency are arranged continuously in the circumferential direction of the disk without being spaced apart from each other. that the inner diameter portion arranged one location on a portion of the servo cylinder servo signal pattern written with a single servo signal frequency to the outer diameter Disk apparatus according to symptoms. Servo cylinders that are concentrically formed from the inner diameter part to the outer diameter part of the disk surface are divided into predetermined areas, and different servo signal frequencies are recorded and set for each divided area. In the disk medium that arranges the servo signal pattern of the servo signal frequency set for each ,
A region where the servo signal frequency is set to the second servo signal frequency in a region where the servo signal frequency is set to the first servo signal frequency and a region adjacent to the region where the servo signal frequency is set to the first servo signal frequency The servo signal pattern written at the first servo signal frequency and the servo signal pattern written at the second servo signal frequency are arranged in the same servo cylinder at the boundary In the region, the servo signal patterns of the first servo signal frequency and the second servo signal frequency are arranged continuously in the circumferential direction of the disk without being spaced apart from each other. placing one location on a portion of the servo cylinder servo signal pattern written with a single servo signal frequency from the inner diameter portion of the surface to the outer diameter Disk medium characterized.

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