KR100576909B1 - How to Prevent Head Hifly Recording on Hard Disk Drives - Google Patents

Abstract

end. The technical field to which the invention described in the claims belongs

Head high-fly write-protection technology for hard disk drives

I. The technical problem that the invention is trying to solve

It prevents data writing on the high fly of the head of the hard disk drive, and further prevents errors in data writing of the hard disk drive.

All. Summary of the Solution of the Invention

Detects the level of the signal read out from the servoburst provided for the head track center following in the servo field of the sector in which data is to be recorded, and performs the data recording operation when the detected signal level falls below the level previously set to the normal level. Outputs a data write protection signal that does not operate.

la. Important uses of the invention:

It can be applied to the head high fly write protection of the hard disk drive.

Description

How to Prevent Head Hifly Recording on Hard Disk Drives

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard disk drive (hereinafter also referred to as a drive), and more particularly to a method for preventing high fly recording of a head for recording information on a magnetic disk for information recording.

A hard disk drive stores information in a magnetic form on a magnetic disk (hereinafter referred to as a disk) for storing information, and is widely used as an auxiliary memory device of a computer system due to its high information storage rate. In addition, the recent increase in the use of personal computers has been increasing its use.

The hard disk drive magnetizes data transmitted from an external host (host computer) to an electric signal according to the data using a head to record data on a disk on which a magnetic layer is formed, and records the data. The magnetized form on the disk is converted into an electrical signal through the head to read data recorded in the magnetized form. The head then floats and moves on the disk. This will be described in more detail with reference to FIG. 1.

1 is a diagram illustrating a head high-fly of a hard disk drive. In general, a hard disk drive includes a disk 18 that rotates at high speed by an internal spindle motor 22 and a magnetic head for recording or reading data recorded on a track of the disk 18. An actuator arm 17 having a head 16 attached thereto is provided. The actuator arm 17 is rotatably installed about the pivot axis 19 and the bobbin 8 and the coil installed at one end thereof move by the operation of the voice coil motor 6, and the suspension 15 end of the other end is moved. The head 16 attached to it moves across the disc 18 to record or read data in the track on the disc 18.

At this time, the head 16 attached to the front end of the suspension 15, which moves to both ends of the disk 18 by the high-speed rotation of the disk 18 by the spindle motor 22, moves to both ends of the disk 18, and is raised to about 0.15 to 0.2 micron. Maintains a fine lift height.

While maintaining the height of the injury, the head 16 records data by magnetizing the data recording surface of the disk 18, or reads the recorded data by detecting the magnetization state of the disk 18 surface, and the height of the head 16 is the information recording capacity of the disk 18. As the capacity becomes higher (high density), it is gradually decreasing for the magnetization operation of the recording surface to increase the track density and the bit density.

By the way, the data recording surface of the disk 18 may not have a perfect horizontal surface but may have fine irregular surfaces due to various factors in the manufacturing process. In this case, the head 16 is caused by the air flow on the surface of the disk 18. Therefore, as shown in FIG. 1A, the head 16 may rise higher on the surface of the disk 18 in the uneven and raised portions of the disk 18 surface. Can be. This is called the high-fly of the head.

When the head 16 rises high, the distance between the head 16 and the data recording surface of the disk 18 becomes far, so that the magnetization force that magnetizes the data recording surface of the disk 18 of the head 16 drops, so that the data is not recorded correctly or the recorded data is read out. This becomes difficult. In particular, since data is not recorded correctly, there is a problem that data loss may occur due to incorrect recording of valid data. The high fly in Head 16, which can cause this problem, may affect dozens of sectors of data recorded sector by sector.

It is therefore an object of the present invention to provide a method capable of preventing data writing on the high fly of the head of a hard disk drive.

Another object of the present invention is to provide a method of preventing an error in writing data of a hard disk drive to reduce the loss of valid data.

In order to achieve the above object, the present invention detects the level of the signal read out from the servo burst provided for the head track center following in the servo field of the sector in which data is to be recorded so that the detected signal level is set to the normal level in advance. If less than this, characterized in that for outputting a data write prevention signal for controlling not to perform the data write operation.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific details such as specific components are shown, which are provided to help a more general understanding of the present invention, and it is understood that these specific details may be changed or changed within the scope of the present invention. It is self-evident to those of ordinary knowledge in Esau.

First, a hard disk drive to which the present invention is applied will be described. 2 is a schematic block diagram of a hard disk drive to which the present invention is applied. Referring to FIG. 1, the microprocessor 10 may include a programmable read only memory (PROM) 12 storing a predetermined control program and data of the microprocessor 10, and a static random access memory (SRAM). 14) to control the overall operation of the drive.

The head 16 is attached to one end of the actuator to rise to a predetermined height on the rotating disk 18, which is a recording medium, and is driven into and out of the disk 18 to write data to or read data from the disk 18 surface. The voice coil motor (VCM) 20 located at the other end of the actuator having the head 16 attached to one end drives the head 16 in response to the applied current level and direction.

The spindle motor 22 normally rotates the disk 18 mounted on the drive shaft in accordance with a control signal input from the motor driver 24. The VCM driver 26 is connected to the VCM 20 to control the driving of the VCM 20. The digital-to-analog converter (DAC) 28 is connected to the microprocessor 10 and the VCM driver 26, receives a digital control signal from the microprocessor 10, and converts the digital control signal into an analog signal and outputs the analog signal to the VCM driver 26.

The motor driver 24 is connected to the spindle motor 22 and the microprocessor 10 and controls the driving of the spindle motor 22 under the control of the microprocessor 10. The pre-amplifier 30 is connected to the head 16 to amplify and output the reproduced signal and output a signal to be recorded to the head 16.

The read / write channel circuit 32 is connected to the microprocessor 10, the preamplifier 30, and the disk data controller (DDC) 34. The read / write channel circuit 32 receives data to be recorded from the DDC 34 under the control of the microprocessor 10, encodes the data, and outputs the preamplifier 30 to the preamplifier 30. do. In addition, the read / write channel circuit 32 digitally converts an analog reproduction signal input from the preamplifier 30 and outputs the encoded read data (ERD).

An analog-to-digital converter (ADC) 36 is connected to the read / write channel circuit 32 to receive an analog servo reproduction signal, digitally converts it to PES, and outputs the same to the microprocessor 10. A gate array 38 is connected to the read / write channel circuit 32 to receive an ERD signal and detects and outputs servo information such as a gray code in the servo region of the disc 18.

The DDC 34 has a sequencer that performs operations according to the microprograms downloaded from the microprocessor 10. The DDC 34 stores data received from an external data input device (e.g., a host computer) through a read / write channel circuit 32 and a preamplifier 30. Record on 18 or read data from disk 18 and send it to an external data input device. The DDC 34 also interfaces the host computer with the microprocessor 10. The DDC 34 also temporarily stores data transmitted between the host computer, the microprocessor 10 and the read / write channel circuit 32 in the buffer RAM 35.

The microprocessor 10, which controls the overall operation of the drive, controls the DDC 34 in response to read or write commands received from the host computer and controls track search and track following. The PROM 12 stores the above-described operating program of the microprocessor 10 and various setting values.

According to an aspect of the present invention, a hard disk drive having the above-described configuration detects a level of a signal read from a servoburst provided for following a head track center in a servo field of a sector in which data is to be recorded, thereby detecting a signal level. When it is less than the level set in advance to the normal level, a data write prevention signal that does not perform a data write operation is output. This will be described in detail with reference to the accompanying drawings.

3 is an illustration of one track sector format of a disc. FIG. 3 shows an example of a sector format diagram for any of the data recording tracks arranged concentrically on the data recording surface of the disc 18. FIG. Referring to FIG. 3A, one track is composed of a plurality of sectors, and the sectors may be divided into a servo field and a data field.

Servo information is recorded in the servo field, and the servo field is shown in detail in FIG. Referring to (b) of FIG. 3, the servo field includes an auto gain control (AGC) section, a servo synchronous signal section (SYNC), a servo address mark (SAM) section, and an index (Index). : IDX) section, Gray Code section, Servo Burst (A, B, C, D) section and PAD section for On-Track position chair of head.

The servo field having the above-described configuration provides information and configuration useful for recording data in the data field of each sector or reading the recorded data. In order to record data in one sector or to read recorded data through the head 16, an operation of first reading the information of the servo field as described above is required. Hereinafter, the servo bursts A, B, C, and D in the servo field will be described in detail.

FIG. 4 is a diagram for describing a servo burst signal used in the present invention in FIG. 3. Referring to Fig. 4, the burst signals A and B are used in track search in combination with track information recorded in the gray code section. That is, as shown in FIG. 4, the burst signal A is recorded on the odd track (n track), and the burst signal B is recorded on the even track (n-1, n + 1 track) to provide excellent and excellent track information. . Alternatively, the burst signal A may be recorded in the even track and the burst signal B in the odd track to provide track information.

On the other hand, the burst signals C and D are recorded as half values between adjacent tracks around the track center line to provide a position error signal (PES) for the head 16 to follow the track center. That is, the head 16 as shown in Fig. 4 uses the burst signals C and D to follow the track. The difference between the voltage level of the burst signal D and the voltage level of the burst signal C is PES. When the head 16 follows the center of the track, the voltage level of the burst signal C and the voltage level of the burst signal D become equal, and the difference is zero. As the position of the head 16 is offset from the track center to the left and right (off track), the difference value becomes positive or negative, and the value indicates the bias direction and the degree of bias of the head 16.

In the present invention, the head high fly is detected using the burst signal. That is, when the head is high fly, the level of the read signal is reduced. Therefore, when the head is high fly, the level of the burst signal is also reduced. Since the burst signals, particularly the burst signals C and D, are signals provided collectively in each sector, the level of the read burst signal can be expected. Therefore, if the level of the read burst signal is less than expected, it can be regarded as a head high fly.

On the other hand, there may be a number of factors other than the head high fly as a cause of decreasing the level of the read burst signal. However, the lower the level of the burst signal, the less reliable the read signal. Even if the level is reduced, it means that a malfunction can occur in data recording.

With reference to the accompanying drawings, an embodiment of the present invention for determining the possibility of a data write operation according to the level of the burst signal read out will be described. Fig. 5 is a circuit diagram of an essential part of an apparatus and related part of a head high fly write prevention apparatus according to an embodiment of the present invention. The gate array 38 as shown in FIG. 5 is the same as the gate array 38 as shown in FIG. 2, and the gate array 38 includes the corresponding gate sector 38 in the read information of the servo field of the corresponding sector as shown in FIG. 3. It checks whether data can be recorded, and if data cannot be recorded in the sector, a data write prevention signal for preventing data from being written in the sector is output.

As shown in FIG. 5, the data write prevention signal includes a WUS (Write UnSafe) signal generated when a head line 16 is disconnected, a FSAM signal generated when a SAM is not detected, and a gray code. The gate array 38 is output when the FGRAY signal generated when it is not detected and the PES (Position Error Signal) in the state indicating that the position control of the head 16 is impossible in the PES.

In the case of outputting the write protection signal, the case of the high fly of the head 16 is further configured according to the feature of the present invention. The burst signals used in accordance with the features of the present invention to detect the high fly of the head 16 are applied to the high fly detector 40 as shown in FIG.

The high-fly detector 40 may be configured as a comparator, and the comparator outputs a comparison result by comparing the detected burst signals C and D with a level set by subtracting the threshold level from the average burst signals C and D in advance. It is to. The threshold level is to allow a certain level even if the level of the read burst signal is lower than the average level, and the comparator outputs an output signal of a "high" state when the difference is greater than or equal to the threshold level.

That is, the comparator 40 is a value of an average value of the sum of the level of the burst signal C and the level of the burst signal D. The non-inverting input terminal receives the signal V1 having the level minus the preset limit level Vlim from the preset level. A signal V2 having a level equal to the sum of the level of the burst signal C and the level of the burst signal D read from the servo field of one sector to which data is to be recorded is applied to the inverting input terminal. When the level of V2 is greater than V1, the level of the output signal of the first comparator 42 is "low". However, when the level of V2 is less than V1, the level of the output signal of the first comparator 42 is "high."

In the configuration in which the level of the preset burst signal is compared with the level of the read burst signal, and when the level of the read burst signal is low, the level signal as much as the difference value is outputted. Although only one signal may be used, the burst signals C and D are used as described above to obtain a read signal having a relatively accurate level even when the head 16 does not accurately follow the track center line. In addition, the use of a value obtained by dividing the levels of two burst signals is intended to avoid a case where the sum of the levels of the two burst signals C and D is too high.

With the above configuration, the output of the comparator is applied to the gate array 38, and when the output of the comparator is "high", the gate array outputs the data write protection signal of the corresponding sector.

When the data write protection signal is output as described above, the microprocessor 10 detects this and does not perform a data write operation on the corresponding sector.

As described above, the present invention detects the level of the signal read out from the servoburst provided for the head track center following in the servo field of the sector in which data is to be recorded so that the detected signal level is less than the level previously set to the normal level. In this case, by outputting a data write prevention signal that does not perform a data write operation, it is possible to prevent data writing on the high fly of the head of the hard disk drive, and furthermore, to prevent errors during data recording of the hard disk drive, thereby enabling effective data. There is an advantage to reduce the loss of.

1 is a view for explaining the head high-fly (high-fly) of the hard disk drive

2 is a schematic block diagram of a hard disk drive to which the present invention is applied.

3 shows an example of one track sector format of a disc.

4 is a view for explaining a servo burst signal used in the present invention of FIG.

5 is a circuit diagram of an essential part of an operation related to preventing head hi-fly writing according to an embodiment of the present invention;

Claims (2)

A method for preventing head high fly writing of a hard disk drive, Reading predetermined burst signals of a sector to be written in the hard drive; Comparing the average voltage level of the read burst signals with a predetermined normal level; Determining that the burst level is high when the average level of the burst signals is less than or equal to the normal level; And if it is determined that the head high fly is performed, a data recording operation of the corresponding sector is not performed. The method of claim 1, wherein the burst signals are C and D which are signals for estimating a track center.