KR960012892B1 - Magnetic disk drive units - Google Patents

Abstract

No summary

Description

Offset measuring circuit of data head of magnetic disk device

1 is a schematic explanatory diagram of a magnetic disk device.

2A, 2B and 2C are diagrams for explaining offset detection and offset correction.

3 is a diagram for explaining servo information stored on a data recording surface.

4 is an explanatory diagram showing an example of a method of recording servo information on a data recording surface.

5 is an explanatory diagram showing another method of recording servo information on the data recording surface.

6A, 6B, and 6C are explanatory diagrams of the read signals of the servo information in the off track of the data head.

7 is a graph showing the characteristic of the deviation signal band offset obtained from the servo information.

8 is an explanatory diagram of servo information on a data recording surface having an AGC area.

9 is an explanatory diagram showing a signal read out from the servo information on the data recording surface using the AGC area.

10A is an explanatory diagram showing an embodiment summarized by the first and second aspects of the present invention.

FIG. 10B is a graph showing detection of a proportionality constant in FIG. 10A.

11 is an explanatory diagram showing an embodiment summarized by the third and fourth aspects of the present invention.

12 is an opening diagram of a magnetic disk device according to embodiments of the present invention.

13A and 13B are opening views of the disc drive device of FIG.

A flow chart showing the processing of the offset detector in FIG. 13 according to the first and second aspects of the present invention in FIG.

15 is an explanatory diagram showing a storage state of a proportionality constant obtained by offset detection.

Fig. 16 is a schematic diagram showing a storage state of an offset by proportional constants obtained by offset detection.

17 is an opening diagram showing the conversion circuit of FIG.

18 is a waveform diagram showing waveforms of the conversion circuit and a position signal obtained from the output of the conversion circuit.

19A and 19B are explanatory diagrams showing offset measurement processing including interrupts due to access from a main apparatus in one embodiment of the third and fourth aspects of the present invention.

20A and 20B are explanatory diagrams showing another offset measurement process including interrupts due to access from a main apparatus in another embodiment of the third and fourth aspects of the present invention.

21 is a cross-sectional view of a disk enclosure of a magnetic disk device according to one embodiment of the present invention.

FIG. 22 is a side sectional view of the disk enclosure of FIG.

The present invention relates to a magnetic disk apparatus for controlling the position of a head by servo information recorded on a servo disk and correcting an offset of the head by servo information recorded on a data recording, and according to the third or fourth aspect of the present invention. Relates to a circuit for measuring the intrinsic offset of a data head corrected by the head positioning control of the magnetic disk device during operation of the magnetic disk device.

Increasing the storage capacity of the magnetic disk apparatus requires an increase in the number of disk media, the number of heads, and the track density arranged on the disk element.

When the recording medium and the track density are increased, the data head controlled to be on-track on the data recording surface by the servo information recorded on the servo recording surface is changed in particular from the low temperature to the high temperature or the high temperature when the environment of the device changes. At low temperatures, it can easily slide off the track. If the datahead is off track, no data is read at all.

In order to prevent the data head off track due to the change of the ambient temperature, the offset (off track amount) of the data head with respect to the on track position is obtained by reading the servo information recorded on the disk surface at regular intervals.

When the track is accessed for reading or writing data, an offset correction operation is performed to remove the offset by moving the selected data head.

Even if a positional deviation occurs between the servo recording surface and the data recording due to the change in the ambient temperature, the above technique can control the data head to the on-track position.

Since the sensitivity of the signal readout for the servo information on the data recording surface depends on the head clearance and the characteristics of the amplifier, the proportionality constant due to the fixed sensitivity is insufficient to accurately detect the offtrack state. Improvements are desired in this regard.

The offset used for the offset correction is measured, for example, by an interrupt executed according to a set of time schedules in response to a change in ambient temperature. During the measurement of the offset, an access command such as a write or read command from the main device must be waited until the measurement distance is completed. These shortcomings must be addressed.

In a magnetic disk apparatus, the rotating shaft of the spindle motor has four magnetic disks that rotate at a constant speed, for example.

Of the magnetic disks, both sides of the upper three disks and the upper side of the bottom disk have a data recording surface, and the bottom side of the bottom disk has a servo recording surface.

A data head is provided on the data recording surface of the magnetic disks, and a servo head is provided on the servo recording surface.

The data heads and servo heads are driven together by a voice coil motor (hereinafter referred to as VCM) to traverse the tracks on the magnetic disk.

In the servo recording surface on which the servo head is arranged, servo information is recorded for each cylinder position. The signals read by the servo head provide position signals indicative of the track on which the servo head is placed.

The data recording surfaces on which the data heads are placed contain servo information, which is recorded on the track of a particular cylinder or in the empty space of a sector of every cylinder and used to detect the offset of the data head.

The servo head and the data head 2 are in the center of the cylinder and therefore no offset correction is necessary. Due to the difference in the expansion coefficients of the metals used for the head actuator, the center of the data head is usually the cylinder in which the servo head is placed. Depart from the center

The offset of the data head is: (1) a thermal offset caused by the difference in expansion coefficients of the head actuator by ambient temperature; (2) external force offset caused by an external force applied to the head actuator; (3) may include an offset due to magnetic force of magnets that change according to the rotational position of the VCM.

The offset of the data head is measured during operation of the magnetic disk device and stored in the memory. When positioning the head, the measured offset is removed by shifting the head to accurately position the data head on the cylinder center.

The column offset of (1) can be measured for each data head and can correct the offset of one of the selected data heads and the like.

The external force offset of said (2) should be measured about the specific head on all cylinders in principle. However, this is cumbersome, so that the measured offset of the target cylinder by measuring the offsets of the head with respect to the predetermined number of cylinders is eliminated during the seek operation by controlling the speed by supplying a predetermined current VCM.

The seek operation for removing the external force offset is described, for example, in Japanese Patent Laid-Open No. 62-149082.

The servo information recorded on the data recording surface of the conventional magnetic disk device is as follows. That is, the first servo information A for a predetermined frequency signal, for example, the maximum write frequency signal, is recorded on the optical track on the data recording surface at an X mu m position outward from the on-track position of the data head, The servo information B is recorded at an X mu m position inward from the on track position.

The servo information can be recorded in a specific track on the data recording surface or in an empty space of all sectors on the data recording surface.

When the data head is on track, the head reads the servo information A and B evenly to provide the same signals V _A and V _B.

When the data head is off tracked Y 탆 outward, the head reads servo information A of the servo information B or more to provide a large signal V _A and a small signal V _B.

The servo control processor reads the deviation signals V _A -V _B between the signals V _A and V _B read out by the data head to obtain an offset.

The relationship between the offset and the deviation signal (V _A -V _B ) can be expressed as a predetermined proportional constant as indicated by the continuous line.

The output of the data head varies with the floating amount of the head, the fluctuation of the head core width, and the circumferential speed. Therefore, the relationship between the offset signal and the deviation signal V _A -V _B by the servo information cannot be expressed as a constant, but is different for each data head. For example, some dataheads have poor sensitivity, i.e. low proportionality.

Therefore, the prior art which gives a constant proportionality constant to the output characteristics of all data heads cannot accurately correct the offset.

This problem can be solved by the AGC area disposed in front of the servo information A and B.

That is, an amplification gain for providing a constant head output is determined in the AGC region. By this amplification gain, even if the signals read out for the servo information A and B are amplified and the output of the head is changed, the deviation signals V _A -V _B of the read signals can be constant for the same offset. .

In the case of using the AGC region, the relationship between the offset and the deviation signal (V _A -V _B ) read out for the servo information A and B does not always follow the proportionality constant but fluctuations in the amplification gain and the head writing and reading variability. Is shaken according to. That is, there is still a problem of incorrect offset correction.

According to the conventional offset measurement method, the microprocessor for controlling the seek operation and the on-track operation is used solely for the measurement of the offset of the data head during the measurement, so that the main device generates a write or read command including the seek operation. This will prevent the higher order from being executed during this measurement.

Only after the measurement can the high order be executed. This causes a delay in the higher command and thus impairs the performance of the device.

That is, when the offset measurement is started, the column offset of each data head is detected in accordance with the servo information recorded on the data recording surface on which a specific cylinder is seeked.

To measure the external force offset, all cylinders on a particular data record surface are in principle sequentially detected to detect the offset for each cylinder.

Thus, the offset measurement takes about several hundred milliseconds, that is, several hundred times the time required to process the high order. In addition, a drive control microprocess is used entirely for the seek operation of the offset measurement. This causes a delay in the execution of the high order instruction and impairs the performance of the device.

In particular, the offset measurement is performed at very short intervals, for example, at 1 minute intervals, immediately after the power is turned on in a large range of ambient temperature change. In this case, high-level orders are frequently queued, which impairs system efficiency.

Related arts of the present invention are disclosed in Japanese Patent Laid-Open No. 62-266781.

The object of the first or second aspect of the present invention is to solve the above problems of the prior art on the data surface of a magnetic disk device capable of accurately detecting an offset from the servo information on the data recording surface even when the head output is shaken. A sensitivity correction circuit for servo signal detection is provided.

It is an object of the first or second aspect of the present invention to provide an offset measuring circuit of a magnetic disk device that processes high order as quickly as possible even when performing offset measurement.

According to the first aspect of the present invention, the first servo information A is recorded with a predetermined amount of outer offset from the on-track position, and the second servo is recorded with a predetermined amount of inner offset from the on-track. Disk media each having information (B); A data head provided corresponding to the disk medium; The data head reads the signals V _A and V _B relating to the first and second servo information A and B on one disc medium, and the deviation signals V _A -V _B of the read signals. Offset detection means for detecting an offset of the data head by multiplying a proportionality constant K representing the output sensitivity of the data head; Offset storage means for storing an offset of each data head; Servo signal detection on the data recording surface of the magnetic disk apparatus having offset correction means for correcting the position of the selected data head for reading or writing one disk medium to remove the offset of the selected data head stored in the offset storage means. In the sensitivity correction circuit; Installed in the offset detecting means to offset one data head outward from the on-track position by a predetermined amount X1, and the signals V _A and V _B relating to the first and second servo information _A and _B ; Is read, the deviation signal V1 of the read signals is detected, and then the data head is offset inwardly by the predetermined amount X2 from the on-track position, and the signal relating to the first and second servo information ( And a sensitivity detecting means for reading V _A , V _B ), detecting the deviation signal V 2 of the read signals, and calculating a proportional constant K for the data head according to the deviation signals V 1, V 2. A sensitivity correction circuit is provided.

According to the second aspect of the present invention, the first servo information A is recorded with the predetermined amount of outer offset from the on-track position, and the second recorded with the predetermined amount of inner offset from the on-track. Disk media each having servo information (B); A plurality of data heads provided corresponding to the disk medium; The data head reads the signals V _A and V _B related to the first and second servo information A and B on one disc medium, and the deviation signals V _A -V _B of the read signals are read. Offset detection means for detecting an offset of the data head by multiplying a proportional constant K representing the output sensitivity of the data head; Offset storage means for storing an offset of each data head; Sensitivity correction circuit for detecting servo information on a data recording surface having offset correction means for correcting the position of the selected data head for reading or writing one disk medium to remove the offset of the selected data head stored in the offset storage means. In a magnetic disk device using a; The sensitivity correction circuit; Installed in the offset detecting means to offset one data head outward from the on-track position by a predetermined amount X1, and the signals V _A and V _B related to the first and second servo information _A and _B ; Is read, the deviation signal V1 of the read signals is detected, and then the data head is offset inwardly by the predetermined amount X2 from the on-track position, and the signal related to the first and second servo information ( And a sensitivity detecting means for reading V _A and V _B , detecting a deviation signal V 2 of the read signals, and calculating a proportional constant K for the data head in accordance with the deviation signals V 1 and V 2. A magnetic disk apparatus is provided, characterized in that

According to the third aspect of the present invention, a plurality of disk media, a plurality of data heads installed in correspondence with another disk medium and a servo head provided in correspondence with one disk medium, and a command supplied by the main device are decoded. And an offset control circuit for a magnetic disk apparatus having a command control section for generating an internal command and a drive control section for performing head positioning control on the disk medium by an internal command supplied by the command control section, wherein the data recording surface of the disk medium is provided. Offset detection means for detecting an offset of the data head relative to the servo head based on the servo information read by the data head of the data head; Measurement timing setting means for instructing said offset detecting means to start detecting processing according to a predetermined time schedule; When the command control unit decodes an access instruction such as a read or write instruction supplied by the main device, it interrupts the offset detection processing, first executes the access instruction, and when the detection processing by the offset detection means is executed, the access instruction After this is finished, an offset measuring circuit is provided, comprising interrupt means for restarting the offset detection process.

According to the fourth aspect of the present invention, a plurality of disk media, a plurality of data heads installed in correspondence with another disk medium and a servo head provided in correspondence with one of the disk media, and a command supplied by the main device are decoded. A magnetic disk apparatus using an offset measuring circuit of a magnetic disk apparatus having a command control section for generating an internal command and a drive control section for performing head positioning control on the disk medium by the internal command supplied by the command control section, Offset measurement circuit; Offset detection means for detecting an offset of the data head relative to the servo head by servo information read out by the data head on the data recording surface of the disk medium; Measurement timing setting means for instructing said offset detecting means to start detecting processing according to a predetermined time schedule; When the command control unit decodes an access instruction such as a read or write instruction supplied by the main device, it interrupts the offset detection process, first executes the access instruction, and when the detection process by the offset detection means is executed, the access instruction After this is finished, there is provided a magnetic disk device comprising interrupt means for restarting the offset detection process.

Other features of the present invention can be clearly understood from the following description with reference to the accompanying drawings. Before describing the embodiments in detail, the related art of the present invention will be supplementarily described with reference to the drawings and an outline of the embodiments will be described.

1 is a schematic diagram of a magnetic disk device. The rotating shaft of the spindle motor 38 has, for example, four magnetic disks 1, which are rotated at a constant speed.

Of the magnetic disks 1, both of the upper three disks and the upper side of the bottom disk have a data recording surface, and the lower side of the bottom disk has a servo recording surface.

Data heads 2 are provided on the data recording surfaces of the magnetic disks 1, and a servo head 34 is provided on the servo recording surfaces.

The data head 2 and the servo head 34 are driven together by a voice coil motor to traverse the tracks on the magnetic disk 1.

The servo surface on which the servo head 34 is provided has servo information recorded in all cylinder positions. The signals read out by the servo head 34 provide position signals indicating the track on which the servo head 34 is located.

The data recording surfaces on which the data head 2 is provided have servo information, which is recorded on a track of a specific cylinder or in an empty space of a sector of all cylinders to detect the offset of the data head 2. It is used to

2A, 2B and 2C are explanatory diagrams showing detection of offset of a data head.

In FIG. 2A, since the servo head 34 and the data head 2 are located at the center of the cylinder (dashed line), offset correction is not necessary at all.

Due to the difference in the coefficient of expansion of the metal used for the head operator, the center of the data head 2 is usually deviated from the center of the cylinder in which the servo head 34 is arranged, as shown in FIG. 2B.

The cause of the offset of the data head 2 is as described above.

The offset [alpha] of the data head 2 shown in FIG. 2B is measured during the operation of the magnetic disk device.

When positioning the head, the measured offset α is removed by shifting the head to accurately position the data head 2 on the cylinder center.

3 shows servo information recorded on the data surface of a conventional magnetic disk apparatus.

In FIG. 3, the first servo information A relating to a predetermined frequency signal, for example, the maximum write frequency signal, is recorded on an arbitrary track on the data recording surface at an X mu m position outward from the track position of the data head 2. The second servo information B is recorded at an X mu m position inward from the on track position.

The servo information can be recorded on a specific track 9 on the data surface 8 as shown in FIG. 4 or in the empty space of all sectors on the data surface 8 as shown in FIG. .

When the data head 2 is on track, the head reads the servo information A and B evenly as shown in Fig. 6A, and the same signals V _A and V _B are provided.

In the case where the data head 2 is off-tracked Y mu m outward as shown in Fig. 6B, the head reads out more servo information B than the servo information A so that the large signal V _A and the small signal V _B To provide.

When the data head 2 is Ym off-tracked inward as shown in Fig. 6C, the head reads out more of the servo information B than the servo information _{A, so} that the large signal V _B and the small signal V _A are read. to provide.

The servo control processor reads the deviation signals V _A -V _B of the signals V _A and V _B read by the data head 2 and obtains an offset.

The relationship between the offset and the deviation signal V _A -V _B may represent a predetermined proportional coefficient as indicated by the continuous line in FIG. 7.

The output of the data head 2 changes depending on the floating amount of the head, the fluctuation of the head core width, and the circumferential speed. Therefore, the relationship between the offset and the deviation signal V _A -V _{B based} on the servo information cannot be represented by a constant proportional constant and is different for each data head. For example, as indicated by the dashed line in FIG. 7, some dataheads exhibit poor sensitivity, ie low proportionality.

Therefore, the prior art which applies a constant proportional constant to the output characteristics of all dataheads cannot accurately correct the offset.

This problem can be solved by the AGC area 10 disposed in front of the servo information A and B as shown in FIG.

As shown in FIG. 9, an amplification gain for providing a constant head output is obtained on the AGC area 10. FIG. By the amplification gain, the signals read out with respect to the servo information A and B are amplified so that the deviation signals V _A -V _B of the read signals are constant with respect to the same offset even when the output of the head is changed. .

Even with this AGC region 10, the relationship between the offset and the deviation signal V _A -V _B read out with respect to the servo information A and B does not always follow the proportional constant, but fluctuations in the amplification gain and head writing. It is shaken according to the over read variability. In other words, an incorrect offset correction problem remains.

Embodiments according to the first and second aspects of the present invention will be described with reference to FIG. 10A.

In this embodiment, a disc medium having a first servo information A recorded with a predetermined amount offset from the on-track position to the outside and a second servo information B recorded with a predetermined amount offset from the on-track position to the inside (1). )Wow ; The data head 2 reads the signals V _A and V _B on the first servo information A and the second servo information B on one disk medium 1, and the deviation signals V _A -V _B of the read signals. An offset detector (3) which detects the offset of the data head by multiplying the proportional constant K representing the output sensitivity of the data head and stores the offset of each data head in an offset storage section 4; An offset correction unit for correcting the position of the selected data head 2 for reading or writing one disk medium 1 to remove the offset of the selected data head 2 stored in the offset storage unit 4 ( 5) Applicable to the magnetic disk device provided.

A circuit for correcting the sensitivity of the servo signal detection on the data recording surface of the magnetic disk device is provided in an offset detector 3 to offset one data head outward from the on-track position and to provide the first and second servo information. A sensitivity detector 6 for reading out the signals V _A and V _B relating to A and B and detecting the deviation signal V1 of the read signals is provided. The sensitivity detector 6 then offsets the data head 2 inward from the on-track position by a predetermined amount X2, reads V _A and V _B for the first and second servo information, and reads out the read data. Deviation signal V2 of the signals is detected and a proportionality constant K for the data head is calculated according to the deviation signals V1 and V2.

The sensitivity detector 6 calculates the proportional constant K as follows:

K = (X1-X2) / (V1-V2)

In the above formula, X1 is an outer shift, X2 is an inner shift, V1 is a deviation signal of signals read with respect to the first and second servo information A and B having an offset X1, and V2 is a first and second having an offset X2. This is a deviation signal of the read signals with respect to the servo information A and B.

The sensitivity detector 6 stores the proportional constant K of each of the data heads in the sensitivity storage 7.

The sensitivity detector 6 first detects the proportional constant K for one data head 2, and then reads the signals relating to the first and second servo information A and B into the data head 2 at the on-track position. The deviation signal V _A -V _B is obtained, and the offset signal V _A -V _B is multiplied by the proportional constant K to calculate the offset of the data head and stored in the offset storage unit 4. .

According to this embodiment, the data head 2 to be the offset detection object is controlled to the on-track position by the servo information read from the servo disk, and the next data head is moved for offset detection.

The sensitivity correction circuit for servo signal detection on the data recording surface of the magnetic disk device forcibly shifts the head position two or more times for all the data heads to obtain deviation signals of the signals V1 and V2 read out for the servo information A and B, The offset of the data head is obtained using the proportionality constant (sensitivity) obtained from the actual output of the data head. Therefore, even if the output of the data head is fluctuated, the present embodiment can set the proportional constant peculiar to the data head, and can accurately detect the offset of the data head.

Next, in the present embodiment, the offset is corrected and the data head is correctly placed on the track even when the track is read or written even if there is a change in the ambient temperature.

An outline of an embodiment according to the third and fourth aspects of the present invention will be described with reference to FIG.

This embodiment is based on a command control microprocessor unit (MPU) 14 for decoding a command supplied by the main device 90 and generating an internal command, and by an internal command supplied by the command control MCU 14. It is applicable to a magnetic disk apparatus having a drive control MCU 40 which performs head positioning control on the disk medium 1.

The offset measuring circuit according to the embodiment applicable to the magnetic disk device includes a data head 2 related to the servo head 34 by servo information read by the data head 2 on the data recording surface of the disk medium 1. An offset detector 3 for detecting an offset of; A measurement timing setting circuit 94 for instructing the offset detector 3 to start detection processing according to a predetermined time schedule; When the command control MCU 14 decodes an access command such as a read or write command supplied by the main device 90, interrupts the offset detection process and executes a high order first, and after the high command ends, The interrupter 5 which restarts the said offset detection process is provided.

The offset detector 3 performs the offset detection process for the data head 2 in a predetermined order, detects the offset of the data head currently being measured when the interrupt command is received from the interrupter 95, and interrupts the process. .

The offset detector (3) is used to determine the signals read out with respect to the first servo information A and the second servo information B offset in different directions by a predetermined amount from the track center read by the one data head 2 on the data recording surface. The deviation signal V _A -V _B is obtained, the deviation signal V _A -V _B is multiplied by the predetermined proportionality K, and the offset of the data head is detected.

The measurement timing setting circuit 94 provides the measurement timing at intervals according to the change of the ambient temperature immediately after the power of the apparatus is turned on.

The interrupter 95 resumes the interrupted offset detection process, except that the main device 90 does not generate a command for a predetermined continuous time.

The offset measuring circuit of the magnetic disk apparatus according to the embodiment of the above configuration performs offset measurement in the magnetic disk apparatus according to a predetermined time schedule. When the main device supplies a write or read command during the offset measurement, the system interrupts the offset measurement, positions the head through seek operation by a higher order, and executes the write or read command in priority. .

Thus, the present embodiment minimizes the waiting time for high order execution due to the offset measurement, thereby improving the efficiency and performance of the apparatus without compromising the offset measurement function.

12 is a schematic diagram showing a magnetic disk device according to one embodiment of the first and second aspects of the present invention.

In the twelfth aspect, the magnetic disk apparatus mainly includes a disk control unit 12 and a disk driving unit 30.

The disk control unit 12 includes a command control MCU 14 for performing centralized control. The common control MCU 14 is connected to the disk drive unit 30, the serial / parallel converter 20, the data transfer buffer 24, and the system through the internal bus 28, the high interface 16, and the drive interface 18. It is connected to the storage unit 26.

The drive interface 18 transmits control commands from the command control MCU 14 to the disk drive unit 30.

The serial / parallel converter 20 writes or reads data from the disk drive unit 30 through the data modulator / demodulator 22.

The serial / parallel converter 20 and the data modulator / demodulator 22 usually constitute a VFO (variable frequency oscillator) unit.

Write or read data is stored in the data transfer buffer 24 and then transferred to the disk drive unit 30 or the main CPU.

The disk drive section 30 includes a drive control MCU 40 and a read / write section 31. The spindle motor (SP) 38 rotates a plurality of magnetic disks 1 serving as a storage medium at a constant speed. Heads are arranged relative to the magnetic disks 1 and are moved across the track of the disk by a voice coil motor (VCM) 36.

The uppermost of the heads is the servo head, and the remaining ones are data heads 2 appended with (2-1) to (2-n).

The servo head 34 reads a servo disk among the magnetic disks 1. The servo information is recorded at all cylinder positions (all tracks) on the support surface.

The data heads 2-1 to 2-n write or read data disks among the magnetic disks 1. For example, servo information is recorded on each data surface as shown in FIG. 4 and FIG. The servo information on the data surface is provided with respect to a predetermined frequency signal as shown in FIG. 3, for example, the maximum written frequency signal recorded at a position shifted by an X mu m outward from the on-track position of the data head 2. And the first servo information A and the second servo information B recorded at a position shifted inward from the on-track position by an X mu m.

FIG. 13 including FIG. 13A and FIG. 13B is a schematic diagram showing the disk drive unit 30 of the embodiment of FIG.

In FIG. 13, the disk drive section 30 has a microprocessor (MPU) 40 which functions as a main control section.

The disc encapsulation body (DE) 56 has a head actuator 60 driven by the voice coil motor 36. The head actuator 60 is connected to the servo head 34 and the data heads 2-1 to 2-n.

21 and 22 are cross sectional and side cross-sectional views, respectively, of the disk enclosure of the magnetic disk apparatus. In the figure, 97 is the axis and 98 is the arm.

The servo signal read out by the servo head 34 is demodulated by the servo demodulation circuit 42 into two position signals POSN and POSQ, which are converted into phase shift pulses and track crossing pulses by the conversion circuit 44. Divided. These pulses are supplied to the microprocessor 40.

The microprocessor 40 has a servo processing section realized by program control, and includes a position detector 46, an addition point 48, and a servo compensation section 50.

The servo compensation unit 50 provides position control data to the voice coil motor 36 for on-track control performed after a seek operation, so that the position signal from the position detector 46 always tracks the center of the track. Can be represented. The servo compensation unit 50 has a function of compensating the advanced phase by increasing the high frequency gain of the servo signal.

The position control data from the microprocessor 40 is converted into an analog voltage by the DA converter 52, and this voltage power is amplified by the analog 54 to drive the voice coil motor 36.

The microprocessor 40 has an offset detector 75, an offset storage unit 77, and an offset correction unit 79.

The offset detector 75 performs an offset detection process by an interrupt executed according to a predetermined time sequence after the power supply of the magnetic disk apparatus is turned on.

The offset detection process is executed at an interval of, for example, one minute immediately after the power is turned on with the ambient temperature largely changed, in some cases thereafter for ten minutes, and one hour after the temperature is stabilized and saturated.

The offset detector 75 receives the deviation signals V _A -V _B due to the signals read by one of the data heads 2-1 to 2-n.

The data heads 2-1 to 2-n are connected to a head selector 62, which is read by one of the data heads in response to a select signal from the microprocessor 40. The signal is supplied to the peak hold circuits 64 and 66.

The peak hold circuit 64 holds the peak value V _A of the signal read out with respect to the first servo information A recorded on the data recording surface by the timing controlled by the microprocessor 40.

The peak hold circuit 66 holds the peak value V _B of the signal read out with respect to the second servo information B recorded on the data recording surface at a timing controlled by the microprocessor 40.

The deviation circuit 68 provides the deviation signals V _A -V _B of the output signals of the peak hold circuits 64, 66.

This deviation signal (V _A -V _B ) is converted into digital data by the AD converter 70, and the digital data is read by the offset detector 75 of the microprocessor 40.

The data write or read operation by the data heads 2-1 to 2-n is executed through the read / write control circuit 72 and the read / write circuit 74. At this time, the head selector 62 is controlled by the microprocessor 40 so that a specific data head reads or writes data.

FIG. 14 is a flow chart showing an offset data detection process performed by the offset detector 75 of FIG.

An interrupt executed according to the time schedule after the power is turned on starts the offset detection process in FIG.

In step S1, the head seeks a predetermined track position (or cylinder position). As shown in FIG. 4, when the servo information is placed on the data recording surface, the head is moved to a specific track 9, and the servo information is recorded thereon. When the servo information is recorded in the empty space of the sector as shown in Fig. 5, the head moves to an arbitrary track position. After the head is moved to the track position through seek operation, the head is controlled to the on track position according to the servo information supplied by the servo head 34. In step S2, the data head 2-1 is selected as the first head.

In this embodiment, it is assumed that there are six magnetic disks 1. Each side of each disc has a recording surface. Therefore, there is one servo head 34 and eleven data heads 2-1 to 2-n. That is, there is one datahead from 1 to 11.

In step S3, the data head is forcibly shifted outward from the on-track position by a predetermined amount of X1 mu m. Next, in step S4, the deviation signal V1 = (V _A -V _B ) of the read signals with respect to the servo information A and B is read.

In step S5, the data head is shifted inward from the on-track position by a predetermined amount of X2 mu m. In the next step S6, the deviation signal V2 = (V _A -V _B ) of the signals read with respect to the servo information A and B is read.

In step S7, the proportional constant K1 indicating the output sensitivity of the head 1 is calculated as follows, and the value K1 = (X1-X2) / (V1-V2) is temporarily stored in the system storage unit or the like.

In step S8, it is checked whether the head is last. If not the final head, in step S9, the head is switched to the next, and the process returns to step S3. Steps S3 to S7 are repeated to detect the proportional constant Kn.

When the last head is detected in step S8, as shown in FIG. 15, in step S10, the offset storage unit 77 stores the proportional constants K1 to K11 of the heads 1 to 11 calculated above.

Next, each of the data heads 2-1 to 2-11 provides a deviation signal V _A -V _B from signals read out with respect to the servo information at the on-track position. The deviation signals are each multiplied by the previously detected proportional constants K1 to K11 shown in FIG. 15 to provide offsets OF1 to OF11. The offsets OF1 to OF11 of each head are stored in the offset storage unit 77 as shown in FIG.

As shown in FIG. 16, once the offset of each head is stored, there is no particular need to preserve the proportional constant of each head shown in FIG.

Referring back to FIG. 13, the offset storage unit 77 stores offsets of FIG. 16 obtained from proportional constants of FIG. If one of the selected data heads executes a seek operation by a write or read command from the high level disk control device 12, one of the offsets corresponding to the selected data head is transferred from the offset storage 77. A correction signal for reading out and moving the head to remove the offset is supplied from the offset correction unit 97 to the addition point 48, and at this addition point, the correction signal is supplied by the servo head 34. The offset correction is completed by adding the position data by the servo information.

Even if any of the data recording surfaces deviate from the servo recording surface due to the change in the ambient temperature, the corresponding data head can be accurately controlled at the on-track position after the seek operation ends.

FIG. 17 is a schematic diagram showing an example of the conversion circuit 44 of FIG.

In FIG. 17, the conversion circuit 44 generates the signals N > Q and Q (N + Q) > 0 ' in FIG. 18 by the position signals POSN and POSQ supplied by the servo demodulation circuit 42. In FIG. A phase conversion signal generating circuit 76 is provided.

The two output signals from the phase shift signal generation circuit 76 are supplied to the edge detection circuit 78, which supplies the track crossing pulse TXPL shown in FIG. 18 after edge detection.

The track crossing pulse TXPL from the edge detection circuit 78 is counted by the counter circuit 80, and the number of tracks traversed by the corresponding head is obtained.

The signal from the counter 80 and the two output signals from the phase shift signal generating circuit 76 are supplied to the latch circuits 82, 84 and 86, respectively.

The latch circuits 82, 84, and 86 receive a common latch control signal from the microprocessor 40, and latch the three signals simultaneously. Next, the microprocessor 40 sequentially reads the latched data.

In this way, the three latch circuits 82, 84, 86 simultaneously latch the output signals of the counter circuit 80 and the phase shift signal generation circuit 76 and the microprocessor 40 latches the latched signals. Read out sequentially. If the microprocessor 40 alternately executes the head position control and the high command execution in accordance with the timer interrupt, the head position control may be interrupted because of the time required to execute the high command. The head position control can then be resumed. In this case, there is a time delay. Even with this time delay, the head latch control can be accurately maintained without being affected by the time delay by using the data latched simultaneously.

As described above, irrespective of the output fluctuations of the datahead, this embodiment forcibly offsets each datahead, actually reads signals through each datahead, and determines the sensitivity of the dataheads according to the readout signals. Obtain Next, this embodiment accurately detects the deviation between the data recording surface and the servo recording surface caused by the change in the data head offsets, i.e., the ambient temperature. Therefore, in the present embodiment, accurate on-track control is realized by writing or reading offset correction.

An embodiment according to the third and fourth aspects of the present invention will be described with reference to FIG. In FIG. 12, the magnetic disk apparatus of this embodiment includes a disk control section 12 and a disk drive section 30. In FIG.

The disk control unit 12 includes a command control microprocessor 14 for executing centralized control.

In order to measure the offsets according to the present embodiment, the command control microprocessor 14 functions with the function of the measurement timing setting circuit 94 shown in the schematic diagram of FIG. 11 to provide an instruction to start offset detection according to a predetermined time schedule. When a read or write command from the main device is decoded during the offset detection, the interrupter 95 has the function of interrupting the offset detection, executing the command first, completing the command, and then restarting the offset detection.

The function of the measurement timing setting circuit 94 can be realized by the disk drive unit 30.

The command control microprocessor 14 includes a disk drive unit 30, a serial / parallel converter 20, and a data transfer buffer 24 through an internal bus 28, a high interface 16, and a drive interface 18. And the system memory 26.

The drive interface 18 transmits a control command from the command control microprocessor 14 to the disk drive unit 30.

The serial / parallel converter 20 transmits write or read data to the disk drive unit 30 through a data modulator / demodulator 22.

The serial / parallel converter 20 and the data modulator / demodulator 22 usually constitute a VFO unit.

The write or read data is once stored in the data transfer buffer 24 and then transferred to the disk drive unit 30 or the main CPU.

The disk drive section 30 includes a drive control microprocessor 40 and a read / write section 31. The spindle motor (SP) 38 rotates a plurality of magnetic disks 1 serving as a storage medium at a constant speed. Heads are arranged with respect to the magnetic disks 1, which are moved across the tracks of the disk 1 by a voice coil motor (VCM) 36.

The uppermost of the heads is the servo head 34, and the remaining ones are the data heads 2-1 to 2-n.

The servo head 34 reads a servo disk among the magnetic disks 1. The servo information is recorded at all cylinder positions (all tracks) on the servo recording surface.

The data heads 2-1 to 2-n write or read discs having data recording surfaces of the magnetic discs 1.

The servo information is recorded sector by sector on each data recording surface. That is, as shown in FIG. 3, the first servo information A for a predetermined frequency signal, for example, the maximum write frequency signal, is the on-track position of the data head 2 on a specific track on the data recording surface of the magnetic disk. The second servo information B is recorded at the position shifted by the X mu m shifted inward from the on-track position.

As shown in FIG. 4, the servo information can be recorded on a specific track 9 on the data recording surface 8 or in an empty space of all sectors on the data recording surface 8 as shown in FIG. .

When the data head 2 is in an on-track state, the head reads servo information A and B evenly as shown in FIG. 6A to provide the same signals V _A and V _B.

When the data head 2 is offtracked to the outside as shown in FIG. 6B, the head reads the servo information A rather than the servo information _B to provide the large signal V _A and the small signal V _B.

When the data head 2 is offtracked inward as shown in FIG. 6C, the head reads out the servo information B more than the servo information _A, thereby providing a large signal V _B and a small signal V _A.

The drive control microprocessor 40 disposed in the disk drive unit 30 reads the deviation signals V _A -V _B of the signals V _A and V _B read by the data head 2 during the offset measurement, Detect the offset.

In this case, the relationship between the offset and the deviation signal V _A -V _B is represented by a constant proportional constant (tilt) K as shown in FIG. 7 (continuous line).

Therefore, the offset α can be calculated by multiplying the proportional constant by the deviation signals V _A -V _B of the read signals with respect to the servo information A and B on the data recording surface.

That is, the offset α for the servo information on the data recording surface is calculated as follows:

α = K · (V _A -V _B )

FIG. 13 including FIG. 13A and FIG. 13B is a schematic view showing the disc drive section 30 of the embodiment of FIG.

In FIG. 13, the disk drive section 30 has the drive control microprocessor (MPU) 40 which functions as a main controller.

The disc enclosure (DE) 56 has a head actuator 60 driven by the voice coil motor 36. The head actuator 60 is connected to the servo head 34 and the data heads 2-1 to 2-n.

The servo signal read out by the servo head 34 is demodulated by the servo demodulation circuit 42 into the two-position signals POSN and POSQ and these signals are provided to the conversion circuit 44.

As shown in FIG. 18, the conversion circuit 44 converts the position signals POSN and POSQ from the servo demodulation circuit 42 into a (N> Q) signal and a (N + Q)> 0｝ signal. Convert

The edges of the two signals are detected to generate a track crossing pulse TXPL with which the counter counts the number of tracks traversed by the head. In the figure, CY represents a cylinder.

The signals from the conversion circuit 44 are read by the position detector 46 of the microprocessor 40 to generate position data (position signals) that change linearly for each track as shown in FIG. do.

It is inherently possible to detect the head speed in accordance with the period of the track crossing pulse TXPL supplied by the conversion circuit 44.

The microprocessor 40 has a servo processing section realized by program control, and includes a position detector 46, an addition point 48 and a servo compensation section 50. The position detector 46 performs speed control of the seek operation and position control of the on-track operation.

That is, the detector 46 moves the head to the target track through the seek operation by the feedback control of the target speed and the head moving speed.

Once the head reaches the target track through seek operation, the speed control is switched to position control to place the head in the on-track position.

The servo compensation unit 50 provides position control data to the voice coil motor 36 for on-track control on the target track, whereby the position signals from the position detector 46 (see FIG. 18) can be obtained. You can always mark the center of a track.

The servo compensation unit 50 has a function of compensating the advanced phase by increasing the high frequency gain of the servo signal.

The speed or position control data from the drive control microprocessor 40 is converted into an analog voltage by the DA converter 52 and its power is amplified by the power amplifier 54 to drive the VCM 36. The microprocessor 40 includes an offset detector 75, an offset storage unit 77, and an offset correction unit 79.

The offset detector 75 performs an offset detection process every time an internal command is received to start the measurement from the command control microprocessor 14 of FIG. 12 after the power supply of the magnetic disk apparatus is turned on.

The offset detection process is performed at short intervals immediately after the power is turned on by a large change in the ambient temperature and at long intervals, for example, one hour after the temperature has stabilized and saturated.

The offset detector 75 receives the deviation signals V _A -V _B of the signals read by one of the data heads 2-1 to 2-n.

In response to the switching signals from the data heads 2-1 to 2-n, signals read by the data heads 2-1 to 2-n are sent to the peak hold circuits 64 and 66. Feed them one by one.

The peak hold circuit 64 holds the peak value V _A of the signal read out with respect to the first servo information A on the data recording surface at a timing controlled by the microprocessor 40.

The peak hold circuit 66 holds the peak value V _B of the signal read out with respect to the second servo information B on the data recording surface at a timing controlled by the microprocessor.

The deviation circuit 68 provides the deviation signals V _A -V _B of the output signals of the peak hold circuits 64 and 66. This deviation signal V _A -V _B is converted into digital data by the DA converter 70, and the digital data is read by the offset detector 75 of the drive control microprocessor 40.

The offset detector 75 uses the proportional constant K having the characteristics shown in FIG. 7, and calculates an offset α when it is a column offset for each of the data heads 2-1 to 2-n. The obtained offset is stored in an offset storage unit 77 which is a RAM.

If the offset is an external force offset, a specific datahead, for example datahead 2-1, is selected and an offset is detected for all of the predetermined number of cylinders. The obtained offset is stored in the offset storage unit 77. It is inherently possible to detect an offset for all cylinders, calculate an average offset for all of the predetermined number of cylinders, and store this average offset in the storage section.

The data writing or reading operation by the data heads 2-1 to 2-n is executed through the read / write control circuit 72 and the read / write circuit 74. At this time, the head selector 62 is controlled by the microprocessor 40 to cause a specific data head to read or write data.

The offset measurement performed by the offset detector 75 of the drive control microprocessor 40 of FIG. 13 will be described with reference to the time charts of FIGS. 19A and 19B. Thermal offsets are measured as an example in FIGS. 19A and 19B.

When B1 of the command control microprocessor 14 detects the measurement start time, B2 issues a seek command to the drive control microprocessor 40 as an internal command for seeking a specific cylinder S for which a column offset is detected.

Upon receiving the command, C1 of the drive control microprocessor 40 moves the heads onto the particular cylinder.

B3 of the command control microprocessor 14 supplies an internal command to cause the drive control microprocessor 40 to measure the column offset of head zero.

Upon receiving the command, C2 of the drive control microprocessor 40 detects the column offset of the 0 header. That is, the microprocessor 40 selects the data head 0, and reads the signals V _A and V _B related to the servo information A and B on the data recording surface with the selected data head, and the read signal V is read. _a deviation signal from the V _B - obtaining the (V _a V _B), and calculates the offset α is multiplied by a predetermined proportional constant K on the deviation signal.

B4 and B5 sequentially supply offset measurement commands to the heads 1 and 2, and C3 and C4 measure the offset.

A1 of the main device 90 issues a read command to the cylinder A during the offset detection at C4 by the offset measurement command to the head 2 supplied by B5.

Upon receiving the read command, the command control microprocessor 14 waits for the supply of offset detection of C4 to the head 2, and issues a seek command to cylinder A of B6 in accordance with the high order. That is, offset measurement is interrupted at C5.

The cylinder A is struck, and if the head is on track, the data is read and transmitted to the host 90 through the buffer.

Upon completion of the high read order, B7 issues a seek command for the particular cylinder S and C6 seeks the particular cylinder S. Next, in order to resume the interrupted offset measurement, B8 issues an offset measurement command for the subsequent head 3, and C7 detects the offset of the head 3.

The offset detection is repeated up to the final head n. Bn completes a series of offset measurements and normalization resumes.

20A and 20B are time charts showing offset measurement processing according to another embodiment of the present invention. This embodiment also measures the thermal offset as an example. In the figure, automatic adjustment means an offset measurement process.

In the embodiment of Figs. 20A and 20B, the drive control microprocessor 40 sets the measurement timing and receives an instruction from the command control microprocessor 14 to start interrupt processing for the high order.

That is, unlike the embodiment of FIGS. 19A and 19B, the drive control microprocessor 40 of this embodiment has an intelligent function for offset measurement.

In B1 to B6 and C1 to Cn, the command control microprocessor 14 and the drive control microprocessor 40 transmit and receive an internal command for offset detection, interrupt the offset detection upon receiving a high command, and complete the high command. Offset detection resumes at time.

According to another embodiment of the present invention, the resumption of the offset measurement of B7 of FIGS. 19A and 19B and B6 of 20A and 20B does not cause the host 90 to issue a command for at least a predetermined time after the termination of the preceding high order. Can only be achieved when.

If the master device 90 commands randomly temporarily, the offset measurement can be resumed without any problem at the end of the current high order instruction. But. When the main device issues a write or read command sequentially, the high order and offset measurements are performed alternately, which impairs the sequential access efficiency.

Therefore, after the current high command ends, the offset measurement is resumed if no high command is issued for a predetermined time, e.g., 1 ms.

That is, the offset measurement is not resumed after the completion of each high order in the case of sequential access, thereby preventing the loss of processing performance of the sequential access.

The number of magnetic disks and heads in this embodiment is exemplary and can be appropriately determined.

In this embodiment, the servo recording surface is formed on one end of one of the plurality of disks. The servo recording surface may be formed on the central disk or on any other disk.

As described above, the embodiments interrupt the offset measurement upon receiving the high command during the measurement, and first execute the high command to prevent the loss of processing performance due to the offset measurement.

Claims (6)

A plurality of disk media 1, a servo head 34 provided corresponding to one of the disk media 1, a plurality of data heads 2 provided corresponding to the other disk media 1, and a main device 90 A command control unit 14 for decoding a command supplied by the control unit and generating an internal command, and a drive control unit 40 for performing head positioning control on the disk medium 1 by an internal command supplied by the command control unit 14. In the offset measurement circuit of the data head of the magnetic disk device having a; Offset detection means (3) for detecting an offset of the data head (2) relative to the servo head (34) by the servo information read by the data head (2) on the data recording surface of the disk medium (1); Measurement timing setting means (94) for instructing said offset detecting means (3) to start detection processing according to a predetermined time schedule; When the command control unit 14 decodes an access command such as a read or write command supplied by the main device 90, it interrupts the offset detection process, first executes the access command, and then executes the offset detection means (3). And an interrupt means (95) for resuming the offset detection process after the access command ends when the detection process is executed. The offset of the data head currently measured at the time of receiving an interrupt instruction from said interrupt means 95, wherein said offset detecting means 3 performs an offset detecting process on said data head 2 in a predetermined order. And an interrupt measurement circuit for interrupting the processing after detecting the error. 2. The first and second servo information (A) according to claim 1, wherein said offset detecting means (3) is offset in a different direction by a predetermined amount from a track center read by one data head (2) on a data recording surface. The deviation signals V _A and V _B of the signals read out with respect to _B ) are obtained, and the deviation signals V _A and V _B are multiplied by the given proportional constant K, and the magnetism characterized by detecting the offset of the data head. Offset measuring circuit of data head of disk device. 2. The offset measurement circuit according to claim 1, characterized in that the measurement timing setting means (94) provides the measurement timing at intervals depending on the change in ambient temperature immediately after the power of the apparatus is turned on. . 2. The offset of the data head of the magnetic disk device according to claim 1, wherein the interrupter means (95) resumes the interrupted offset detection process if the main device (90) does not issue a command for a predetermined continuous time. Measuring circuit. A plurality of disk media 1, a servo head 34 provided corresponding to one of the disk media 1, a plurality of data heads 2 provided corresponding to the other disk media 1, and a main device 90. A command control unit 14 which decodes the command supplied by the controller and generates an internal command, and a drive control unit 40 which performs head positioning control on the disc medium 1 by the internal command supplied by the command controller 14. A magnetic disk apparatus using an offset measuring circuit of a magnetic disk apparatus having; The offset measuring circuit; Offset detection means (3) for detecting an offset of the data head (2) with respect to the servo head (34) by the servo information read by the data head (2) on the data recording surface of the disk medium (1); Measurement timing setting means (94) for instructing said offset detecting means (3) to start detection processing according to a predetermined time schedule; When the command control unit 14 decodes an access command such as a read or write command supplied by the main device 90, it interrupts the offset detection process, first executes the access command, and then executes the offset detection means (3). And an interrupter means (95) for resuming the offset detection process after the access command is terminated when the detection process is executed.