JP2002237005A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic disk device capable of achieving both of a high recording speed and high recording capability reliability for a magnetic signal. SOLUTION: Condition information is stored in a memory, which becomes a criterion for switching a method used for magnetic signal recording from a direct overwrite system (OW system) to an erase and write system (EW system). A control means for recording system switching determines whether the condition information stored in the memory is satisfied or not when a new magnetic signal is recorded. It executes controls to record the magnetic signal by the OW system when the condition information is not satisfied. It executes control to record the magnetic signal by switching to the EW system when the condition information is satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct overwrite method for recording a new magnetic signal without erasing a magnetic signal recorded in a recording area, and a method in which a previously recorded magnetic signal is once applied by a current. The present invention relates to a magnetic disk device that records a magnetic signal on a magnetic disk by an erase-and-write method that records a new magnetic signal after performing an erasing operation.

[0002]

2. Description of the Related Art Conventionally, in a magnetic disk device, when a magnetic signal is recorded in a recording area (data sector) of a magnetic disk, a new magnetic signal is written from a magnetic signal already recorded in the recording area of the magnetic disk. Direct overwrite method (OW
(Over Write method)), the recording speed is improved. However, in the OW method, a new magnetic signal is overwritten and recorded. For this reason,
In the recording area of the magnetic disk, the previously recorded magnetic signal remains without being completely erased, and the remaining portion becomes noise, resulting in a problem that the S / N ratio is reduced. That is, the OW method is a method in which the recording speed is excellent but the recording capability is low.

In the OW system, normal recording cannot be performed in a poor environment such as low temperature and high humidity. Therefore, a temperature region (operation guaranteed temperature region) in which a magnetic signal can be normally recorded at present is present. There is a problem that it is narrow. It is difficult to recover the deterioration of the recording capability of the magnetic signal in the OW system. When recording a magnetic signal by the OW method, conventionally, a recording operation as shown in FIG. 10 has been performed. That is, the magnetic disk device unconditionally records a magnetic signal in an OW system in response to a signal write command from the host system. Thereafter, if the internal temperature of the magnetic disk device at the time of recording the magnetic signal is within the range in which the OW method can normally record, the recording operation is completed assuming that the magnetic signal has been normally recorded. On the other hand, if the temperature inside the magnetic disk device exceeds the range in which normal recording can be performed by the OW method, a recording error occurs, and measures such as re-recording a magnetic signal have been taken.

In order to solve the problem that the recording performance of the OW system deteriorates in a poor environment such as a low temperature and a high humidity, a temperature sensor, a heat generator and a blower are installed in a closed space inside the magnetic disk drive. By keeping the inside of the magnetic disk device always at a predetermined temperature or within a predetermined temperature range,
Method of suppressing deterioration of recording capability in OW system
No. 3-83723) has been proposed.

However, this method requires a configuration in which a heat generator and a blower are provided inside the magnetic disk drive, so that the number of parts is increased, and a space for providing the heat generator and the blower is required. For this reason, the size of the entire magnetic disk device is increased, which is a limitation in downsizing. Further, it is expected that the recording density of magnetic signal recording will further increase in the future, but it is difficult for the OW method having a low recording capacity to cope with the recording density.

[0006] In contrast to the OW method, a magnetic signal recorded in a recording area is first erased once by a DC current (DC current) as a method having an excellent recording capability capable of securing high reliability of recording of a magnetic signal. Then, a new magnetic signal is recorded thereafter, and an erase-and-write method (EW method (Er
case and write method)). However, in the EW method, the magnetic signal recorded on the magnetic disk is preliminarily erased by one round, and the magnetic signal is recorded by the OW method. On the other hand, it takes an extra time for one rotation of the magnetic disk to rotate.
There is a problem that the recording speed is slower than the W method.

[0007]

As described above, OW
The method has a problem that the recording capability deteriorates in a poor environment such as low temperature or high humidity, recording cannot be performed normally, and high reliability of the recording capability of a magnetic signal cannot be secured. As a method of preventing the deterioration of the recording performance of the OW system under a bad environment, a temperature sensor, a heat generator, and a blower are provided inside the magnetic disk device so that the temperature is always kept at a predetermined temperature or within a predetermined temperature range. However, since it is necessary to provide a heater and blower, the number of parts increases,
In addition, it has been a constraint in downsizing the magnetic disk drive.

On the other hand, although the EW system has excellent recording performance even in a poor environment, it has a problem that the recording speed is slower than that of the OW system, and the high-speed recording cannot be ensured.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and uses an EW system having excellent recording capability under an inferior environment such as low temperature and high humidity, and uses an OW system in a normal recording operation. It is an object of the present invention to provide a magnetic disk drive capable of achieving both high reliability of magnetic signal recording capability and high speed of magnetic signal recording speed.

[0010]

A magnetic disk drive according to the present invention is a magnetic disk drive for recording a magnetic signal on a recording area of a magnetic disk by a magnetic head. A direct overwrite magnetic signal recording control means for recording a magnetic signal with the magnetic head using a direct overwrite method of recording a new magnetic signal without first erasing the signal; and An erase-and-write method in which a magnetic signal is recorded by the magnetic head by using an erase-and-write method in which a magnetic signal already stored in the recording area is previously erased by an erase current and then a new magnetic signal is recorded. A write-type magnetic signal recording control means and the direct overwrite-type magnetic signal recording control; Means and the erase-and-write magnetic signal recording control means, so that a new magnetic signal is recorded by one of the direct overwrite method and the erase-and-write method. Recording method switching means.

Thus, the magnetic signal on the magnetic disk can be recorded at a high speed, and the occurrence of a recording error can be suppressed. Therefore, both the high recording speed and the high reliability of the recording capability of the magnetic signal can be achieved. It is possible.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an overview of a magnetic disk drive of the present invention. The magnetic disk drive
It is composed of a plurality of magnetic disks 1, a magnetic head 2, a control circuit 3 for controlling the operation of these, and the like. FIG.
3 is a diagram showing each control circuit constituting the control circuit 3. FIG. The control circuit 3 includes a head amplifier circuit 11, a R / W
Control circuit 12, CPU 13, memory 14, HDC 15,
It comprises a temperature sensor 16 and a humidity sensor 17.
The head amplifier circuit 11 amplifies a recording signal read by the magnetic head 2 from a predetermined recording area of the magnetic disk 1, and when recording a magnetic signal in a predetermined recording area of the magnetic disk 1, Is supplied with a write current. The R / W control circuit 12 controls the magnetic head 2
And decodes the magnetic signal input through the head amplifier circuit 11 by performing various signal processing, and modulates the magnetic signal for writing input from the host system via the HDC 15. . The modulated magnetic signal is output to the magnetic head 2 via the head amplifier circuit 11 and recorded on the magnetic disk 1. CPU 13
Controls each constituent circuit constituting the control circuit 3. CP
U13 executes the dedicated program prepared in advance to execute the OW system and the E in accordance with the predetermined conditions shown in FIG.
Magnetic signal recording control is performed to switch between the W system and record a magnetic signal. The memory 14 records preset condition information serving as a criterion for determining whether to switch from the OW system to the EW system.

The condition information includes, for example, a temperature limit value Tl indicating a usage limit of the temperature T inside the magnetic disk device,
This is a humidity limit value Ml indicating a usage application limit of the humidity M inside the magnetic disk device. FIG. 4 shows a recording capability value of the OW method (a new magnetic signal is recorded on the already recorded magnetic signal) in accordance with the value of each temperature T (temperature at the time of recording the magnetic signal) inside the magnetic disk device. Later, when the new magnetic signal is reproduced, the value indicates the magnitude of the reproduction output of the already recorded magnetic signal remaining without being erased.
W value).

In FIG. 4, the OW value is shown on the Y axis, and its unit is "-dB". Therefore, it can be confirmed that the OW value increases as the temperature T decreases. When a magnetic signal is recorded by the OW method in a low-temperature environment, a previously recorded magnetic signal remains without being erased even after a new magnetic signal is recorded. Therefore, when reading a newly recorded magnetic signal, the previously recorded magnetic signal is mixed. That is, the previously recorded magnetic signal becomes noise,
The newly recorded magnetic signal cannot be read normally. The temperature limit value Tl is a lower limit value of the temperature T at which a magnetic signal can be normally recorded in a preset OW method from the relationship shown in FIG. For example, when “-30 dB” is set as the allowable maximum value of the OW value, the temperature limit value Tl
Is set to about “−10 ° C.”. If the temperature T inside the magnetic disk device falls below the temperature limit value Tl, O
In the W method, the OW value becomes too large, and the probability of occurrence of a recording error increases, so that a normal magnetic signal cannot be recorded.

The humidity limit value Ml is an upper limit value of humidity at which a magnetic signal can be recorded normally. If the humidity M exceeds the limit value Ml, a normal magnetic signal cannot be recorded by the OW method. . This limit value Ml is also a value previously determined from the relationship between the humidity value inside the magnetic disk device and the recording capability value of the OW method.

Further, when recording a signal requiring a certain level of reliability in the recording capability, such as an error correction code, the system is switched to the EW system. Therefore, the memory 1
No. 4 records the type of signal to be recorded in the EW system as condition information. Further, even when the user instructs the recording in the EW system for high reliability in the usage of the magnetic disk device, the switching from the OW system to the EW system is performed. For this reason, control information indicating a recording instruction in the EW system from the user is recorded in the memory 14 as condition information.

The HDC 15 forms an interface with a host system (computer), and controls the transfer of a magnetic signal and control information with the host system.

Next, the operation of switching control between the OW system and the EW system according to the present invention will be described with reference to FIG.
In the present invention, the recording of the magnetic signal is normally performed by the OW method, and the recording is switched to the EW method when the above condition is satisfied.

First, when a write command of a magnetic signal is input from the host system via the HDC 15, the CPU 1
3 detects this (step S1) and determines whether to switch the magnetic signal recording method from the OW method to the EW method (step S2). A specific method of the determination in step S2 will be described below.

FIGS. 5 to 9 are flowcharts showing the specific processing of the judgment in step S2. FIG. 5 shows a case where the determination is made using the measured value of the temperature T inside the magnetic disk device. FIG. 6 shows a case where the determination is made using the measured value of the humidity M inside the magnetic disk device. FIG. 7 shows a case where the determination is made based on the type of a signal to be written which is input from the host system. FIG. 8 shows a case where the determination is made based on whether or not control information for instructing the recording of a magnetic signal in the EW system from the host system is input. FIG. 9 shows a case where the determination is made using all the four conditions described above.

First, the case where the determination is made using the measured value of the temperature T inside the magnetic disk device will be described. As shown in FIG. 5, the CPU 13 acquires the measured value of the temperature T inside the magnetic disk device at the present time (that is, the time when the magnetic signal is recorded) measured by the temperature sensor 16 (step S21), It is determined whether or not the temperature T is lower than the temperature limit value Tl stored in the memory 14 (Step S22). If the temperature T is lower than the temperature limit value Tl, it is determined that switching to the EW method is performed to record a magnetic signal (Yes in step S22), and the process proceeds to step S3 in FIG. On the other hand, if not less, it is determined that recording of the magnetic signal is to be performed in the OW mode (No in step S22), and the process proceeds to step S4 in FIG.

Next, a case where the determination is made using the measured value of the humidity M inside the magnetic disk device will be described. In this case, as shown in FIG. 6, the CPU 13 acquires the current measurement value of the humidity M inside the magnetic disk device measured by the humidity sensor 17 (step S31), and the humidity M is stored in the memory 14. It is determined whether or not the humidity limit value Ml is exceeded (step S32). When the humidity M is higher than the humidity limit value Ml, it is determined that the recording is switched to the EW method and the magnetic signal is recorded (Yes in step S32), and the process proceeds to step S3 in FIG. On the other hand, if not exceeded, it is determined that recording of the magnetic signal is to be performed in the OW mode (No in step S32), and the process proceeds to step S4 in FIG.

Next, a case where the determination is made based on the type of a signal to be written which is input from the host system will be described. As shown in FIG. 7, based on a signal to be written which is input from the host system to the HDC 15, the CPU 13 determines whether the signal to be written is a type to be recorded in the EW format stored in the memory 14. (For example, an error correction code) (step S41). If it is determined that the signal is of a type to be recorded by the EW method, it is determined that the signal is switched to the EW method and the magnetic signal is recorded (Yes in step S41),
It moves to the process of step S3 in FIG. On the other hand, when the signal to be written, which is input from the host system, is not a signal of a type to be recorded in the EW system, it is determined that the magnetic signal is recorded in the OW system (step S41).
No), the process proceeds to step S4 in FIG.

Next, a case where the determination is made based on whether or not control information for instructing recording of a magnetic signal in the EW system from the host system has been input will be described. As shown in FIG.
Determines whether or not control information for instructing the HDC 15 to record a magnetic signal in the EW mode has been input from the host system (step S51). When the control information for instructing the recording of the magnetic signal in the EW mode is input from the host system, it is determined that the switching to the EW mode is performed to record the magnetic signal (Yes in step S51),
It moves to the process of step S3 in FIG. On the other hand, when the control information for instructing the recording of the magnetic signal in the EW mode is not input from the host system, it is determined that the magnetic signal is to be recorded in the OW mode (No in step S51).
It moves to the process of step S4 in FIG.

Next, a case where the determination is made using all four conditions will be described. As shown in FIG.
Acquires the current measured value of the temperature T inside the magnetic disk device measured by the temperature sensor 16 (step S
61), it is determined whether or not the temperature T is lower than the temperature limit value Tl (step S62). Temperature T is the temperature limit value T
l, it is determined that switching to the EW method is to be performed to record a magnetic signal (Ye in step S62).
s), and the process proceeds to step S3 in FIG. On the other hand, if it is not below (No in step S22), then the CPU
13 acquires the current measurement value of the humidity M inside the magnetic disk device measured by the humidity sensor 17 (step S63), and determines whether or not the humidity M exceeds the humidity limit value Ml (step S63). S64). If the humidity M is higher than the humidity limit value Ml, it is determined that switching to the EW method is performed to record a magnetic signal (Y in step S64).
es), the process proceeds to step S3 in FIG. On the other hand, if it does not exceed (No in step S32), then C
The PU 13 determines whether or not the signal to be written is a signal of a type to be recorded by the EW method, based on the signal to be written input from the host system to the HDC 15 (step S65). If it is determined that the signal is of a type to be recorded by the EW method, it is determined that the signal is switched to the EW method and the magnetic signal is recorded (Yes in step S65), and the process proceeds to step S3 in FIG.
On the other hand, when the signal to be written, which is input from the host system, is not a signal of a type to be recorded by the EW method (No in step S41), the CPU 31 then proceeds to
It is determined whether or not control information for instructing recording of a magnetic signal in the EW mode has been input from the host system to the HDC 15 (step S66). E from the host system
If the control information for instructing the recording of the magnetic signal in the W system is input, it is determined that the recording is switched to the EW system and the recording of the magnetic signal is performed (Yes in step S66), and FIG.
Move to the process of step S3. On the other hand, when the control information for instructing the recording of the magnetic signal in the EW mode is not input from the host system, it is determined that the magnetic signal is to be recorded in the OW mode (No in step S66), and FIG.
It moves to the processing of step S4.

The determination in step S2 in FIG. 3 may be made by appropriately combining two or three conditions, instead of using one or all four conditions as described above.

By the way, in the judgment of step S2 in FIG.
If it is determined that recording of a magnetic signal is to be performed in the OW mode (No in step S2 in FIG. 3), the CPU 13
The magnetic signal is recorded by the W method (step S in FIG. 3).
4). That is, the CPU 13 transmits a signal input from the host system to the R / W control circuit 12 and the head amplifier circuit 1.
1 to the magnetic head 2, and the magnetic head 2 overwrites a recording area to be recorded on the magnetic disk 1 with a magnetic signal already recorded in the recording area.

On the other hand, according to the judgment in step S2 in FIG.
If it is determined that the magnetic signal is to be recorded by switching to the new method (Yes in step S2), the CPU 13
A magnetic signal is recorded by the method (step S3). That is, the CPU 13 once erases the magnetic signal recorded in the recording area to be recorded on the magnetic disk 1 by the magnetic head 2 once by the DC current, and then performs the R / W control on the signal input from the host system. The data is output to the magnetic head 2 via the circuit 12 and the head amplifier circuit 11 and newly recorded. Note that the advance erasure of the magnetic signal in the EW system is
Although the DC current is used in the longitudinal recording method as described above, it goes without saying that an AC current (AC current) is used in the perpendicular recording method.

As described above, the recording of the magnetic signal is normally performed by the OW method using the method combining the OW method and the EW method, and is switched to the EW method in the case of a preset condition to record the magnetic signal. Therefore, it is possible to secure the high speed of the recording speed and to secure the high reliability of the recording capability with less occurrence of the recording error.

[0030]

As described above in detail, according to the present invention, when a new magnetic signal is to be recorded in a recording area of a magnetic disk where a magnetic signal has already been recorded, normal recording is performed by the OW method, and is set in advance. Under the conditions described above, the magnetic signal is recorded by switching to the EW method, so that the magnetic signal can be recorded at a high speed and the occurrence of a recording error can be suppressed. It is possible to achieve both high reliability of capability.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing each constituent circuit of a control circuit of the magnetic disk drive of the present invention.

FIG. 3 is a flowchart illustrating a switching control operation of a magnetic signal recording method according to the present invention.

FIG. 4 is a diagram showing a change in recording capability with respect to temperature in the OW system.

FIG. 5 is a flowchart illustrating an operation of determining switching of a recording method using a measured value of a temperature T inside the magnetic disk device of the present invention.

FIG. 6 is a flowchart illustrating an operation of determining switching of a recording method using a measured value of the humidity M inside the magnetic disk device of the present invention.

FIG. 7 is a flowchart showing an operation of determining switching of a recording method based on the type of a signal to be written which is input from the host system of the present invention.

FIG. 8 is a flowchart illustrating an operation of determining switching of a recording method based on whether control information for instructing recording of a magnetic signal in the EW method is input from the host system of the present invention.

FIG. 9 is a flowchart illustrating an operation of determining switching of a recording method using all four conditions of the present invention.

FIG. 10 is a diagram showing a recording operation of a magnetic signal by a conventional OW method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic disk, 2 ... Magnetic head, 3 ... Control circuit, 11 ... Head amplifier, 12 ... R / W control circuit,
13 CPU, 14 memory, 15 HDC,

Claims (5)

[Claims] 1. A magnetic disk device for recording a magnetic signal on a recording area of a magnetic disk with a magnetic head by using a new magnetic signal without previously erasing a magnetic signal already stored in the recording area of the magnetic disk. A direct overwrite magnetic signal recording control means for recording a magnetic signal with the magnetic head using a direct overwrite method for recording a signal, and erasing a magnetic signal already stored in the recording area of the magnetic disk An erase / write method for recording a magnetic signal with the magnetic head using an erase-and-write method of recording a new magnetic signal after preceding erasing with a current.
And write-type magnetic signal recording control means, and switching between the direct overwrite-type magnetic signal recording control means and the erase-and-write type magnetic signal recording control means, and the direct overwrite method and the erase-and-write method. A magnetic disk drive, comprising: a recording method switching means for recording a new magnetic signal by one of the recording methods. 2. A temperature sensor for measuring a temperature inside the magnetic disk device, and a memory for storing a lower limit value of a temperature at which a magnetic signal can be normally recorded when the direct overwrite method is used. The recording method switching control unit determines whether the temperature measured by the temperature sensor is lower than the lower limit stored in the memory, and determines that the temperature is not lower than the lower limit. When controlling to record a new magnetic signal in the direct overwrite method under the control of the direct overwrite method magnetic signal recording control means, if it is determined that the temperature is below the lower limit,
2. The magnetic disk drive according to claim 1, wherein control is performed such that a new magnetic signal is recorded in the erase-and-write system under the control of the erase-and-write system magnetic signal recording control means. 3. A humidity sensor for measuring the humidity inside the magnetic disk device, and a memory for storing an upper limit value of humidity at which a magnetic signal can be normally recorded when the direct overwrite method is used. The recording method switching control unit determines whether or not the humidity measured by the humidity sensor exceeds the upper limit value stored in the memory, and determines that the humidity does not exceed the upper limit value. When controlling to record a new magnetic signal in the direct overwrite method under the control of the direct overwrite method magnetic signal recording control means, when it is determined that the humidity exceeds the upper limit,
2. The magnetic disk drive according to claim 1, wherein control is performed such that a new magnetic signal is recorded in the erase-and-write system under the control of the erase-and-write system magnetic signal recording control means. 4. A memory for storing a type of a signal to be recorded in the erase-and-write method, wherein the recording method switching control means determines whether the type of a signal to be recorded on the magnetic disk is It is determined whether or not the signal is stored in the memory. If it is determined that the signal is not stored in the memory, a new signal corresponding to the signal in the direct overwrite method is controlled by the direct overwrite method magnetic signal recording control means. Control to record the magnetic signal, and if it is determined that the signal is stored in the memory, the erase and write method corresponds to the signal by the erase and write method under the control of the erase and write method magnetic signal recording control means. 2. The magnetic disk drive according to claim 1, wherein control is performed to record a new magnetic signal. 5. The magnetic disk records a magnetic signal in a perpendicular magnetic recording system, and pre-erases a magnetic signal already stored in the recording area under the control of the erase-and-write magnetic signal recording control means. 2. The magnetic disk drive according to claim 1, wherein the step is performed by using an alternating current.