JP3134928B2 - Data recovery circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic disk drive, and more particularly, to a data recovery circuit used in a magnetic disk drive.

[0002]

2. Description of the Related Art Conventionally, as a magnetic disk device of an embedded servo system (data surface servo system), for example, a magnetic disk device described in Japanese Patent Application Laid-Open No. 8-106707 is known. In such a magnetic disk drive, when determining the data read position, the servo mark written in the servo area located before the data read position is used as a reference position, and counting is started from this reference position (resynchronization). Then, reading (data reading) is started from a position where data is likely to be written.

[0003] Generally, the spindle motor has a rotation fluctuation or the like, and the position where the data is to be written and the position where the data is to be read are shifted due to the influence of the rotation fluctuation or the like.

In order to prevent such a problem, a format structure is designed so that reading is possible even if a shift (hereinafter also referred to as fluctuation) occurs between a servo area and the next servo area.

[0005]

In the above-described data read method, if a servo mark becomes unreadable due to a subsequent defect in the servo mark, re-synchronization using the servo mark cannot be performed. In such a state, the operation is performed in a state where resynchronization is performed with the servo mark located in front of the unreadable servo area, and the vibration is equivalent to the distance between the two servos. That is, the swing is doubled.

In the data area after the unreadable servo area, the fluctuation (for two servos) is larger than the fluctuation (for one servo) occurring between the servos.
May occur, making it impossible to perform a read operation in the data area after the unreadable servo area.

It is an object of the present invention to provide a data recovery circuit which can increase the probability of reading data in a data area even when an unreadable servo area occurs. That is, an object of the present invention is to perform data recovery (data recovery processing) when a later defect occurs and a servo mark becomes unreadable after data writing in a data surface servo type magnetic disk device. It is to provide a data recovery circuit which can be used.

[0008]

According to the present invention, a servo area for positioning a head is arranged on a data surface of a magnetic disk at a predetermined interval, and a data area is arranged between the servo areas. Used together with a magnetic disk device of a data surface servo system, a servo mark is defined in the servo area, an interval between the servo areas is stored as a reference interval, and indicates a detailed position of the servo area and the data area. Storage means for storing detailed information; and a lower-level unit for transmitting a servo mark signal when detecting the servo mark when reading data stored on the magnetic disk and transmitting a servo error signal when a read error of the servo mark occurs. Circuit, and counts and calculates the interval of the servo area based on the servo mark signal. A servo interval signal circuit for sending a servo interval signal, a higher-level circuit for sending a restoration signal in response to the servo error signal, and a receiving circuit for receiving the restoration signal based on the current servo interval signal and the reference interval. A current circumferential position calculating circuit for calculating a position of the servo mark where the read error has occurred and correcting the detailed information to generate a circumferential position signal, wherein the lower circuit is indicated by the circumferential position signal A data recovery circuit characterized in that the read operation of the magnetic disk is performed at a timing.

If the current circumferential position calculating circuit does not receive the restoration signal, the current circumferential position calculating circuit outputs a signal indicating that the detailed area is the detailed area when the detailed area indicated by the detailed information is reached based on the servo mark signal. The signal is given to the upper circuit as a circumferential position signal. The upper circuit counts the intervals of the servo area with a reference clock when the spindle motor is at a prescribed number of revolutions, obtains the reference interval, and stores the reference interval in the storage means. When the number is counted, the detailed positions of the servo area and the data area are counted by a reference clock, and the detailed information is obtained and stored in the storage means.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

Referring to FIG. 1, the illustrated data recovery circuit is used together with a magnetic disk device (not shown) of a data surface servo system. In such a magnetic disk drive, servo information (servo marks) for positioning the head is arranged at predetermined intervals on the data surface of the magnetic disk. In the data recovery circuit, after writing data to the magnetic disk device, for example, when a later defect occurs in the servo mark and the servo mark becomes unreadable, data recovery (data recovery processing)
I do.

The higher-level circuit 1 exchanges data with a higher-level device (not shown) and controls each connected circuit based on information from each circuit. The lower circuit 2 receives data from each circuit, and performs data writing to the magnetic disk device, data reading, error detection, and the like.

Now, if the spindle motor is in a predetermined (Type
When the number of rotations is cal), the upper circuit 1 counts the servo-servo (between the servo area and the servo area) by a reference clock (not shown) to obtain a count value. Design value. Then, the upper circuit 1 stores this design value in the reference servo interval circuit 3 as a reference distance (reference interval). Further, the upper circuit 1 stores the detailed servo position information and the detailed data position information in the reference circumferential position circuit 4 at a detailed level in the servo area using the reference clock. That is, when obtaining the servo detailed position information and the data detailed position information, the upper circuit 1 counts using the reference clock to obtain a count value, and according to these count values, the servo detailed position information and the data Find detailed location information.

When reading data, when the spindle motor rotates, the reference servo interval circuit 3 sends the above-mentioned reference distance to the current circumferential position calculation circuit 6 as a reference servo interval signal d. On the other hand, the reference circumferential position circuit 4 sends the detailed servo position information and the detailed data position information to the current circumferential position calculating circuit 6 as a reference circumferential position signal c.

The current circumference position calculation circuit 6 is supplied with the current servo interval signal e from the current servo interval counting circuit 5 and the servo mark signal b from the lower circuit 2 as will be described later. The position calculation circuit 6 includes a reference servo interval signal d, a reference circumferential position signal c, a current servo interval signal e,
The operation timing is calculated in accordance with the servo mark signal b and the circumferential position signal f is output. At the time of normal operation, the current circumferential position calculation circuit 6 starts counting based on the servo mark signal b, and when it reaches each detailed region indicated by the reference circumferential position signal c, the current circumferential position calculation circuit 6 starts counting. This is output as a circumferential position signal f indicating that there is.

The lower circuit 2 performs a seek operation, a servo read operation, a data write operation, and a timing operation at the timing indicated by the circumferential position signal f.
Data read, index generation, sector pulse generation,
Performs various processes such as error detection. Further, the lower circuit 2
Sends a servo mark signal b according to the circumferential position signal f. That is, the lower circuit 2 monitors each detailed area indicated by the circumferential position signal f and performs a process according to each detailed area. For example, when the circumferential position signal f indicates an area in which to search for a servo mark, the lower circuit 2 searches for the servo mark and outputs a servo mark signal b when the servo mark is searched. When the circumferential position signal f indicates the sector pulse position, the lower circuit 2 performs processing such as data read / write.

In response to the servo mark signal b, the current servo interval counting circuit 5 starts counting from the reference position using the servo mark as a reference position (also referred to as re-synchronization). To obtain the servo mark interval. The current servo interval counting circuit 5 manages the history of the servo mark interval. That is, the current servo interval counting circuit 5 stores a value obtained by counting the actual distance between the servos.

Now, the lower circuit 2 makes an error in reading the servo mark (hereinafter referred to as a servo mark read error).
Then, the servo error signal h is turned on (that is, the lower circuit 2 outputs the servo error signal h). When the servo error signal h is turned on, the host circuit 1 performs various error processing. In the upper circuit 1, the servo mark is
When it is found that data is already present in the data area following the servo area corresponding to the servo mark read error and is damaged by the late defect, and approaches the vicinity of the servo area where the error occurred, recovery processing is performed. The recovery signal g is turned on (that is, the recovery signal g is transmitted).

When the recovery signal g is turned on, the current circumferential position calculating circuit 6 compares the reference servo interval signal d, the reference circumferential position signal c, and the current servo interval signal e to determine an error in the current rotational speed. Find the position of the servo mark that has become. That is, the current circumferential position calculating circuit 6 is provided with the current servo interval counting circuit 5.
Current position and the previous servo servo distance from (e.g., to 110 clock) reads and, last service
Based on the servo-servo distance and the value (for example, 100 clocks) indicated by the reference servo interval signal d, a position where a servo mark in which an error has occurred is determined. An example
For example, the position of the servo mark where the error occurred is 1
Seen from the position of the previous servo mark,
In comparison, at the current rotational speed, the number of clocks is 110/100 = 1.
Since it is one time, the distance between servos is 100 × 1.
It is estimated that 1 = 110 clocks. Further, the current circumferential position calculating circuit 6 changes the value (for example, from 50 clocks to 60 clocks) indicated by the reference circumferential position signal c to the actual value (from 55 clocks to 66 clocks) at the current rotational speed. It converts and transmits the circumferential position signal f.

The lower circuit 2 performs a read operation at the timing indicated by the circumferential position signal f. As a result, the read operation can be performed near the true sector pulse position, and as a result, the probability that data can be recovered increases.

[0021]

As described above, in the present invention, the actual servo interval is counted in response to the detection of the servo mark to generate the current servo interval signal, and the reference circle indicating the reference circumferential position of the magnetic disk is obtained. Since the circumferential position signal is corrected based on the current servo interval signal and the data recovery processing is performed, there is an effect that the probability that data can be recovered increases.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a data recovery circuit according to the present invention.

[Explanation of symbols]

 1 Upper circuit 2 Lower circuit 3 Reference servo interval circuit 4 Reference circumferential position circuit 5 Current servo interval counting circuit 6 Current circumferential position calculation circuit

Claims (6)

(57) [Claims] The present invention is used with a magnetic disk device of a data surface servo system in which servo regions for positioning a head are arranged on a data surface of a magnetic disk at a predetermined interval and a data region is arranged between the servo regions. A servo means is defined in the servo area, the interval of the servo area is stored as a reference interval, and storage means stored with detailed information indicating the detailed position of the servo area and the data area, When reading the data stored in the magnetic disk, a lower circuit that sends out a servo mark signal when detecting the servo mark and sends a servo error signal when a read error of the servo mark occurs, based on the servo mark signal. The current servo which counts the interval of the servo area and sends the current servo interval signal An interval counting circuit, a higher-level circuit that sends a restoration signal in response to the servo error signal, and a servo mark in which the read error has occurred based on the current servo interval signal and the reference interval when the restoration signal is received. A current circumferential position calculating circuit for obtaining a position and correcting the detailed information to generate a circumferential position signal, wherein the lower circuit performs a read operation of the magnetic disk at a timing indicated by the circumferential position signal. A data recovery circuit characterized in that it is performed. 2. The data recovery circuit according to claim 1, wherein, if the recovery signal is not supplied, the current circumferential position calculation circuit sets the current circumferential position calculation circuit in a detailed area indicated by the detailed information with reference to the servo mark signal. A data recovery circuit, wherein a signal indicating that the area is the detail area is provided to the upper-level circuit as the circumferential position signal when the data reaches the detail area. 3. The data recovery circuit according to claim 1, wherein the upper circuit counts an interval between the servo areas with a reference clock when the spindle motor is at a predetermined rotation speed to obtain the reference interval, and stores the reference interval. A data recovery circuit, wherein the data is stored in a means. 4. The data recovery circuit according to claim 1, wherein the upper-level circuit counts a detailed position of the servo area and the data area with a reference clock when a spindle motor is at a predetermined number of rotations, and the detailed information is obtained. The data recovery circuit according to claim 1, wherein the data is obtained in the storage means. 5. The data recovery circuit according to claim 1, wherein said storage means includes a reference servo interval circuit in which said reference interval is stored, and a reference circumferential position circuit in which said detailed information is stored. Characteristic data recovery circuit. 6. The data recovery circuit according to claim 1, wherein the upper-level circuit is provided with the circumferential position signal and the servo mark signal, and when the servo error signal is received, the upper-level circuit receives the servo error signal. A data recovery circuit, wherein the recovery signal is transmitted in the vicinity of a servo area where the read error has occurred based on a position signal, the servo mark signal, and the servo error signal.