Patent Application
20070217059
1. Field of the Invention
The present invention relates to a storage device, a control device, and a control method that perform access to data in a storage medium.
2. Description of the Related Art
With development of the information-oriented society, an amount of information goes on increasing. In accordance with the increase in amount of information, a storage device having a large capacity and a low price is required to be developed. In particular, a magnetic disk to which information access is performed by a magnetic field attracts attention as an information rewritable high-density storage medium. A magnetic device which incorporates a magnetic disk and a head therein and performs information access to the magnetic disk is actively researched and developed for a large capacity.
In a general magnetic disk device, a magnetic field is applied to a magnetic disk through a head to record information such that a magnetizing direction of a recording film formed on a surface of the magnetic disk corresponds to the information. As a method to improve a capacity of the magnetic disk device, TPI (the number of tracks per inch) of the magnetic disk is increased. However, in this case, since a distance (track pitch) between adjacent tracks decreases, a highly precise head which can reliably apply a magnetic field to only a track in which information is to be written is required. For example, when TPI of the magnetic disk is set to 100 k, a track pitch is about 250 nm, and positional control in which the head motion amplitude is about ⅙ of the track pitch is required. In this manner, since the head is a very precise part, it is difficult to reliably manufacture all heads at the same precision. For this reason, of heads manufactured to obtain a precision level required for a large-storing-capacity type, a head which reaches the target precision level is used to assemble a large-storing-capacity type magnetic disk device, and a head which does not reach the target precision level is used to assemble a small-storage-capacity type magnetic disk device. As a result, for one series, magnetic disk devices with a plural of storage-capacity types are manufactured.
In a conventional technique, on a recording medium, in addition to user data serving as a target for information access, control data used for various controls such as positioning of a head is recorded. In a magnetic disk device, in order to increase a capacity and a processing speed, a storage area of a magnetic disk is divided into sectors in a circumferential direction of tracks, and servo data for controlling information access is recorded in advance at a start portion of each sector. The servo data is constituted a preamble to adjust a frequency and an amplitude, a servo mark having a data pattern common in all the sectors, a frame expressing a number of the servo data, a gray code expressing a number of a track, a burst expressing allowed motion amplitude, a postcode to correct a vibration component synchronized with rotation, and the like. The preamble is to adjust amplitude and frequency of an analog signal. Amplification or the like of the analog signal is controlled while the preamble is read. Subsequently, the data pattern of the servo mark is detected to acquire a reference position to read the subsequent frame, gray code, burst, and postcode. In this manner, the head acquires the servo data before information access, and positional control or the like is performed on the basis of the acquired servo data.
In a magnetic disk device having a large storage capacity, a head position must be controlled at a high precision by elongating the burst, and a periodical vibration component of the head must be corrected by using the postcode. However, in a magnetic disk device having a small storage capacity, positional control precision required for a head is low because a track pitch is relatively large. For this reason, a postcode in servo data is omitted, or a data length of a burst is shortened, so that a data area storing user data is stored to which information access is actually performed is preferably increased. In this manner, the servo data has different optimum formats depending on the storage capacities or the like of magnetic disk devices. However, in order to read servo data through a head, a format of the servo data must be recognized through the head in advance. For this reason, in magnetic disk devices of the same series, servo data are often written in a format common in storage-capacity types. Therefore, data areas may be decrease in vain, or processing capabilities of the magnetic disk devices cannot be sufficiently brought out, and the capabilities are deteriorated.
Furthermore, in information access, in addition to a preamble or a burst included in servo data, access parameters such as a cut-off frequency of a low-pass filter when user data serving as a target for the information access is read and a detection level of a peak detecting circuit must be appropriately set. These access parameters have optimum values that vary depending on storage-capacity types of magnetic disk devices. However, as in case of servo data, values common in magnetic disk devices of the same series are often set, and access precision is deteriorated.
With respect to this problem, in Japanese Patent Application Laid-open H01-43802, a technique that directly writes parameter values between an index mark (servo data) and data (user data) that is actually read or written. For example, optimum values of access parameters of magnetic disk devices are written between servo data and user data, so that access precision can be improved.
The following method may be effective. That is, servo data are written in formats appropriate to storage-capacity types, a storage-capacity type of a magnetic disk device is determined when servo data is read, and the servo data is read in a format appropriate to the determined storage-capacity type. As an example of the method, PCAs (Plastic Cell Architectures) are prepared, Pull-Up/Down states of the PCAs are associated with the storage-capacity types, respectively, a state of a PCA is read by firmware, and a storage-capacity type is determined on the basis of the read state. In Japanese Patent Application Laid-open H07-161137, a technique that arrange a nonvolatile EEPROM or the like in a magnetic disk device is described. For example, information expressing a storage-capacity type of the magnetic disk device is stored in the EEPROM, and the information stored in the EEPROM is read in advance, so that the storage-capacity type of the magnetic disk device can be determined.
However, a large number of access parameters are prepared to control information access at high precision. When the technique described in JP-A 01-43802 is applied to write the all access parameters between servo data and user data, data area in which the user data is to be recorded decreases, and recording efficiency of a magnetic disk is deteriorated. In addition, in a technique using a PCA or an EEPROM, the PCA or the EEPROM must be newly added to a magnetic disk device, and the device disadvantageously increases in price. In recent years, in addition to an increase in capacity of the storage device, price down is strongly demanded. In fact, in view of the cost and the storage capacity, in magnetic disk devices of the same series, servo data having a common format are recorded, and common access parameters are set in the present circumstances.
The problems are posed in not only a magnetic disk device. The problems are generally posed in fields using a storage device using a storage medium, a control device, and a control method.
The present invention has been made in view of the above circumstances and provides a storage device, a control device, and a control method that can execute access by a method depending on capability of the device while suppressing an increase in cost and deterioration of recording efficiency.
According to the present invention, there is provided a storage device which performs access of data to a storage medium including a head which executes the access to a storage medium, the storage medium having storage areas, each storage area having a data portion in which data is stored and an attached portion attached to the data portion, and control data used in the access to respective data portions to which the attached portion is attached being stored in a data pattern corresponding to a type of an access capability, and a control section which acquires control data from the attached portion at a start of access to a storage area to control the access by the head, determines a type of an access capability corresponding to a data pattern of the control data, and controls the access of head by a control method depending on the determined type.
In a conventional recording medium, control data to control information access is stored. The control data generally includes one data pattern common in storage devices of the same series. In a storage device according to the present invention, data patterns are prepared as control data. Control data having a data pattern, of the data patterns, corresponding to a type of an access capability of the storage device is stored. At a start of access, control data is acquired, and access by a head is controlled by a control method corresponding to a type of access capability corresponding to the data pattern of the control data. Therefore, a PCA, an EEPROM, or the like need not be newly arranged, and precise access can be performed while suppressing an increase in cost. In the storage device according to the present invention, by using control data, both control of access by a head and determination of access capability are performed. For this reason, new data is not required to determine the access capability, and control depending on the access capability can be realized without deteriorating recording efficiency of a storage medium.
In the storage device according to the present invention, the attached portion of the storage area is preferably arranged on an upstream side of the data portion in a direction of the access, and the control data preferably expresses a start of the storage area.
In a conventional technique, a recording area of a magnetic disk is divided into sectors, and servo data to control information access is stored in each sector. A servo mark included in the servo data expresses a start of a sector, and all the sectors generally have a common data pattern. When the servo mark is used as control data according to the present invention, a conventional storage device can be directly converted to the storage device without being considerably changed. The servo mark can be reliably read because the servo marks are stored in all the sectors. The servo marks are used as control data according to the present invention to make it possible to improve redundancy.
In the storage device according to the present invention, the control section positions the head to the storage medium at a precision depending on the access capability, so that the head is preferably caused to execute the access at a recording density depending on the access capability.
As the positioning precision of the head is high, access can be executed at a high recording density.
In the storage device according to the present invention, the control section preferably determines a type of the access capability only when control data is acquired on the head at the beginning.
According to the storage device of the preferred embodiment, once access capability is determined, a determining process is omitted. For this reason, a processing speed of information access can be improved.
According to the present invention, there is provided a control device which controls a head which accesses a storage medium on which a data area in which data is stored and a servo data area attached to the data area are formed, in the servo data area, control data used in the access being stored in a data pattern corresponding to a type of the access capability, including an acquiring section which causes a head to acquire the control data from the servo data area, a determining section which determines a type of access capability corresponding to the data pattern of the control data, and a setting section which performs setting corresponding to the type of access capability determined by the determining section to a circuit attached to the head and used in recording and/or reproducing.
According to the control device of the present invention, a recording medium can be accessed by a method depending on access capability.
In the control device according to the present invention, the control data is preferably a servo mark or a gray code.
The servo mark or the gray code is used as the control data according to the present invention, so that a conventional storage device can be converted to the device according to the present invention without being considerably changed.
In the control device of the present invention, the access capability is preferably a capability depending on a recording capacity of the storage medium or a recording density of the storage medium.
As the recording capacity or the recording density of the storage medium is high, precise access is required.
According to the present invention, there is provided a control method that controls a head which accesses a storage medium on which a data area in which data is stored and a servo data area attached to the data area are formed, in the servo data area, control data used in the access being stored in a data pattern corresponding to a type of the access capability, including the acquiring step of causing the head to acquire the control data from the servo data area, the determining step of determining a type of access capability corresponding to the data pattern of the control data, and the setting step of performing setting corresponding to the type of access capability determined by the determining section to a circuit attached to the head and used in recording and/or reproducing.
According to the control method of the present invention, access can be executed by a method depending on capability of the device.
In the control method of the present invention, the control data is preferably a servo mark or a gray code.
According to an exemplary control method of the present invention, an increase in cost and deterioration of recording efficiency can be suppressed.
In the control method of the present invention, the access capability is preferably a capability depending on a recording capacity of the storage medium or a recording density of the storage medium.
According to the control method of the present invention, the storage medium can be efficiently accessed.
According to the present invention, access can be executed by a method depending on capability of the device while suppressing an increase in cost and deterioration of recording efficiency.
An embodiment of the present invention will be described below with reference to the accompanying drawings.
A hard disk device 100 shown in
As shown in
Here, the explanation of the entire hard disk device 100 is interrupted, and the magnetic disk 103 and data stored in the magnetic disk 103 will be described below.
In the hard disk device 100, magnetic disks 103 are arranged such that the centers of the magnetic disk 103 are adjusted to each other, and the two floating head sliders 104 which face the upper and lower surfaces of each of the magnetic disks. On the magnetic disk 103, coaxial tracks 103a are formed on the surfaces. Data is recorded along the tracks 103a. The storage medium according to the present invention may be a magnetic disk or the like on which a spiral track is formed. On the magnetic disk 103, one set of tracks 103a located at the same position is called a cylinder 103b. The magnetic disk 103 is divided into sectors 103c in a circumferential direction of the tracks 103a, and the data is accessed in units of sectors. The sector 103c corresponds to an example of the storage area according to the present invention.
As shown in
The servo data 310 is constituted by a preamble 311 expressing an amount of amplification of a reproduced signal, a servo mark 312 expressing a start position of the servo data 310, a frame 313 expressing a serial number of the servo data 310, a gray code 314 expressing a serial number of the track 103a, a burst 315 expressing an amount of vibration allowed in the magnetic head 109, and a postcode 316 to correct a stationary vibration component synchronized with rotation. The preamble 311 is data to adjust an amplitude and a frequency of an analog signal. In fact, data subsequent to the servo mark 312 is converted into digital data. The servo mark 312 has a data pattern common in all the sectors 103c. The data pattern is acquired to detect the position of a start position (i.e., a start position of each sector 103c) of the servo data 310. The burst 315 is a parameter having a data length which increases when the precision of positional control of the magnetic head 109 is high. The postcode 316 is a parameter that is added only when the precision of the positional control of the magnetic head 109 is high.
In the steps in manufacturing the hard disk device 100, the precision of the magnetic head 109 which is a precision part does not always reach a target level. The magnetic head 109 is combined to the magnetic disk 103 having a recording density matched to the precision of the magnetic head 109 to manufacture a hard disk device. More specifically, in one series, hard disk devices 100 of storage-capacity types are manufactured. The embodiment will be described on the assumption that in one series, hard disk devices 100 of three storage-capacity types, i.e., a large-capacity type, an intermediate-capacity type, and a small-capacity type are manufactured.
In the hard disk device 100 of the large-capacity type, a track pitch is small because a TPI of the magnetic disk 103 is high, and the position of the magnetic head 109 must be controlled at high precision. For this reason, in the hard disk device 100 of the large-capacity type, the precise magnetic head 109 is incorporated, and the postcode 316 is added to the servo data 310, so that stationary motion amplitude of the magnetic head 109 is precisely corrected.
In the hard disk device 100 of the intermediate-capacity type, the magnetic disk 103 having an intermediate recording density and a magnetic head 109 having an intermediate precision are incorporated. Although the postcode 316 in the servo data 310 is omitted, the data size of the burst 315 is large, and motion amplitude of the magnetic head 109 is descried in detail, so that the position of the magnetic head 109 is controlled at high precision.
In the hard disk device 100 of the small-capacity type, a track pitch is relatively large because a TPI of the magnetic disk 103 is low, and precision required for positional control of the magnetic head 109 is relatively low. For this reason, a low-precision magnetic head 109 is incorporated, the postcode 316 of the servo data 310 is omitted, and the burst 315 has a small data size. In this manner, in the hard disk device of the low-storage-capacity type, the data size of the servo data 310 is suppressed to increase an occupation rate of the user data.
In the hard disk device 100, of three formats shown in
The entire configuration of the hard disk device 100 will be described below again.
As typical magnetic disks and a typical slider shown in
The hard disk device 100, as also shown in
In the embodiment, the access capabilities are classified by storage-capacity types. However, the access capabilities may be classified into capabilities of a high-density type, an intermediate-density type, and a low-density type by track densities (TPI/BPI) of storage media.
In this case, when the user data 320 is accessed, the servo data 310 shown in
When the hard disk device 100 is powered on, data patterns of the servo marks 312 stored in the ROM 121 and associated with the three storage-capacity types (high-capacity type, intermediate-capacity type, and low-capacity type) are transmitted to the hard disk controller 130 by a firmware program in the MCU 120.
Subsequently, the firmware program in the MCU 120 transmits a designation to the servo controller 160 to move the magnetic head 109 onto the magnetic disk 103. The servo controller 160 drives the spindle motor 102 to rotate the magnetic disk 103 and drives the voice coil motor 107 to move the carriage arm 106 by a predetermined distance, so that the magnetic head 109 is moved onto the magnetic disk 103 (step S1 in
The MCU 120 transmits a designation to the read/write channel 140 through the hard disk controller 130 to read data recorded on the magnetic disk 103.
In the magnetic head 109, an electrical signal reproduced corresponding to a magnetic field generated by the magnetic disk 103 is generated. The generated reproduced signal is transmitted to the read/write channel 140.
As described above, since the servo data 310 shown in
Subsequently, in the read/write channel 140, the servo mark 312 is acquired (step S2 in
The read/write channel 140 cuts a signal portion (servo mark portion) subsequent to the preamble 311 in a reproduced signal read by the magnetic head 109.
Subsequently, the servo mark portion is converted into digital pattern data by the following procedure to detect a data pattern of the servo mark 312.
(1) In the servo mark portion, one cycle is divided by four, a peak and a trough of a waveform are digitized into “1”, and others are digitized into “0”, so that NRZI data is generated.
(2) In the NRZI data generated in (1), values are analyzed bit by bit from the start, the values are inverted each time “1” comes, so that NRZ data is generated.
(3) In the NRZ data, the values are determined in units of 4 bits. When a bit string is “0011”, pattern data is generated as “0” and when a bit string is “1100”, pattern data is generated as “1”.
By the procedure, a data pattern “00100111” is acquired from a servo mark portion shown in
In this case, immediately after the device is powered on, a storage-capacity type of the hard disk device 100 is not determined (No in step S3 in
The MCU 120 acquires a format and parameter values associated with the storage-capacity type transmitted from the hard disk controller 130 among the formats (see
In the read/write channel 140, the format and the parameter values transmitted from the MCU 120 are registered in a cache. On the basis of the parameter values, a cut-off frequency or the like of a low-pass filter is set (step S6 in
After the various settings described above, information access is executed according to a designation from the host device 200 (step S7 in
Since the various settings of the read/write channel 140 are performed to make it possible to read servo data, motion of the head can be controlled, and the head can be moved to an SA area (system area) which is accessed at the beginning prior to access to a user data area after the device is powered on. Analysis information of a recording surface, various pieces of control information, and the like are read from the SA area and stored in a memory, or various settings are performed to the circuits on the basis of the information. At this time, a storage-capacity type recorded in the SA area can be correctly determined. Thereafter, the data pattern of the control data (servo data or the like) need not be determined, and the information of the storage-capacity type in the determined SA determined in advance is used in various control operations.
In recording of the user data 320, a recording designation which designates recording of information, the user data 320 to be recorded, and a recording address expressing a position where the user data 320 is written on the magnetic disk 103 are transmitted from the host device 200. In reproducing of the user data 320, a reproducing designation that designates reproducing of the user data 320 and a reproducing address expressing a position where the desired user data 320 is recorded on the magnetic disk 103 are transmitted. When the recording designation is transmitted from the host device 200, the MCU 120 transmits the recording designation and the user data 320 to the hard disk controller 130 and the recording address to the servo controller 160. When the reproducing designation is transmitted from the host device 200, the MCU transmits the reproducing designation to the hard disk controller 130, and the reproducing address to the servo controller 160.
In the magnetic head 109, the user data 320 recorded on the magnetic disk 103 is read to generate a reproduced signal, and the reproduced signal is transmitted to the read/write channel 140.
In the read/write channel 140, the reproduced signal is digitized, and the servo data 310 is acquired in a format registered in a cache with reference to the position of the servo mark 312. The acquired servo data 310 is transmitted to the hard disk controller 130.
In the hard disk controller 130, a track number of the track 103a is acquired on the basis of the gray code 314 of the servo data 310, and allowed motion amplitude of the magnetic head 109 is acquired on the basis of the burst 315. When the postcode 316 is added, a steady state vibration component is acquired on the postcode 316. The acquired values are transmitted to the MCU 120.
In the MCU 120, the values transmitted from the hard disk controller 130 are transmitted to the servo controller 160. The servo controller 160 detects the position of the magnetic head 109 from the transmitted track number and the like, and moves the magnetic head 109 to a position expressed by a designated address in consideration of the transmitted allowed motion amplitude and the steady state vibration component.
When the position of the magnetic head 109 is moved, information is recorded/reproduced. When information is recorded on the magnetic disk 103, recording data transmitted to the hard disk controller 130 is transmitted to the read/write channel 140, and a write current which carries the recording data is applied from the read/write channel 140 to the magnetic head 109. In the magnetic head 109, a recording magnetic field is applied onto the magnetic disk 103 on the basis of the write current. As a result, a magnetizing direction of the recording film of the magnetic disk 103 is made equal to a direction depending on information to record information on the magnetic disk 103. In reproducing of information from the magnetic disk 103, the magnetizing direction of the magnetic disk 103 is detected by the magnetic head 109, and a generated reproducing signal is transmitted to the read/write channel 140. In the read/write channel 140, the reproducing signal is digitized to generate reproducing data. The generated reproducing data is transmitted to the MCU 120 through the hard disk controller 130 and further transmitted to the host device 200. Upon completion of the information access, the magnetic head 109 is retreated out of the magnetic disk 103.
When new information access is executed, the magnetic head 109 is moved onto the magnetic disk 103 (step S1 in
As described above, according to the hard disk device 100 of the embodiment, since a servo mark is used in both detection of a start position of servo data and determination of a storage-capacity type of the hard disk device 100, access can be realized at a precision appropriate to access capability of the storage device while suppressing deterioration of recording efficiency of the magnetic disk 103 and an increase in cost.
The embodiment explains the example in which servo data having a servo mark corresponding to a storage-capacity type of the hard disk device 100 is stored. However, as the control data according to the present invention, control data having a data pattern corresponding to access capability of the storage device may be used. For example, control data having a data pattern corresponding to a processing speed of the storage device may be used.
The embodiment explains the hard disk device that performs information access by a magnetic field. However, the storage device according to the present invention may be an optical information device or the like which performs information access to an MO disk or the like by using light. The present invention may be applied to an information storage device that performs information access to an exchangeable storage medium.
The embodiment explains the example in which servo marks each having data pattern common in all sectors are stored. The control data according to the present invention may be control data having a data pattern common in storage areas.
The embodiment explains the example in which data patterns of servo marks are changed depending on access capabilities. As the control data according to the present invention, data except for the servo mark may be used. Since the burst in the servo data area is an analog signal, pattern recognition of the burst cannot be easily performed, a bit arrangement or a frame number of a gray code of the servo data area may be changed to form data patterns.
In the present invention, heads and storage media of a high-performance (large-capacity or high-density), an intermediate-performance (intermediate-capacity or intermediate-density) type, and a low-performance (small-capacity or low-density) type may be combined to each other to constitute one device.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-076620 | Mar 2006 | JP | national |
