JPS63234465A - Magnetic disk driving device - Google Patents

Abstract

PURPOSE:To execute the positioning of a head with high accuracy by varying the sample signal detecting a servo pattern and detecting the critical value of the deviation of the servo pattern and sample signal. CONSTITUTION:The means detecting the critical value in the deviation of a servo pattern and the sample signal for detecting the servo pattern by changing the timing of the sample signal and the means correcting the timing position of the sample signal set in advance by a calculating the proper timing position of the sample signal from the critical value are provided. The detection of the critical value in the deviation of the servo pattern and sample signal is performed by varying the timing of the sample signal detecting the servo pattern to correct the timing of the sample signal by calculating the proper position of the sample signal at all times. Since the sampling of the servo pattern can be correctly executed without having the effect of a temp. drift, etc., the head can thus be positioned with very high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic disk drive device that uses a magnetic head to write and read information on a magnetic disk surface, and particularly relates to positioning of the magnetic head.

(Prior Art) A magnetic disk drive uses a magnetic head (hereinafter referred to as a head) to write and read information on a magnetic disk surface, and the head must be accurately positioned to a track on the disk surface. need to be

In recent years, there has been a remarkable trend toward smaller size, higher capacity, and higher speed for this type of equipment, and a 3.5-inch thin (41 mm height) type
MB or more (format), average access time 40m
There are also some that are smaller than s. With such a small size and high capacity, the track density also exceeds 100 OTPI (track width 25
μm or less) is required.

As the track density increases in this way, the accuracy of head positioning becomes necessary accordingly, and a closed loop servo system is normally configured using servo information for head positioning written on the disk surface to perform head positioning.

One method of positioning the head using servo information
One type is the servo surface servo method. In the servo surface servo method, servo information for head positioning is written on a dedicated disk surface, and the servo information is read out using a dedicated head.

The servo surface head and the other data surface heads are all mounted on the same drive mechanism and move in unison, with the tracks on the servo surface determining the head position on all data surfaces. The servo head reads servo information from the servo track and sends it to the forward and backward positioning circuits. The servo system is configured to immediately correct any deviation of the head from the center of the track, resulting in highly accurate head positioning.

The servo surface servo method for reading a plurality of pieces of servo information arranged on one track will be explained in detail below with reference to FIGS. 2 to 5.

FIG. 2 is a block diagram showing the configuration of a servo information reading control section and a head positioning control section in the magnetic disk drive device. In the figure, 1 is a microcomputer (
A CPU (hereinafter referred to as μCPU) controls the servo information reading control section and the front/back positioning control section as a whole.

2 is a spindle motor, which is controlled by the μCPUI and rotates at 360 rpm (
It rotates with one rotation period T (approximately 16.67 ms).

4a is a servo disk, 4b is a data disk,
In conjunction with the rotation of the spindle motor 2, the disk 4
The servo information on a is read by the servo head 5a, and the read waveforms of the servo patterns a and b shown in FIG. is input. Further, data is written or read onto the disk 4b by a data head 5b, and the read data is amplified by a read/write amplifier 6b and output as read data to an interface (not shown).

On the other hand, write data from the interface is written to the disk 4b by the magnetic head 5b via the read/write amplifier 6b. Furthermore, a spindle index sensor 8 is provided on the servo disk 4a that operates in conjunction with the spindle motor 2.
The spindle index signal IDX is detected every time the μCP rotates once, and the waveform is shaped by the amplifier circuit 9.
It is input to the UI and the sample timing generation circuit 10,
Furthermore, it is output to an interface (not shown) as an index signal IDX.

11 is an access motor that moves the servo 5a and data head 5b in the radial direction of the disks 4a and 4b;
An encoder 12 is attached to the shaft so that an output can be obtained corresponding to the approximate track position. 13 is a waveform shaping circuit which inputs the output of the encoder 12, shapes it into a pulse waveform, and outputs it to the μCPUI.

14 is a servo circuit, and the head position correction amount, which is a digital value from the μCPUI, is transferred to a digital-to-analog converter (
(hereinafter referred to as DAC) 15 converts it into an analog value,
The access motor 11 is operated by inputting the head position correction amount of the analog value.

Here, the operation of the sample timing generation circuit 10 will be explained in detail with reference to FIG. In response to the spindle index signal IDX input to the sample timing generation circuit 10, the invert circuit 151. A servo synchronization signal SPO having a falling differential waveform is generated by a flip-flop (F, F) 152° AND circuit 153 and output to a timer (TMI) 154 and an OR circuit 155. The timer 154 is configured to generate 15 carry pulses at a period of T/16, which is obtained by dividing the period T of the spindle index signal IDX into 16, and starts at the falling differential waveform, that is, the servo period signal SPO. . The carry pulse of the timer 154 is the servo synchronization signal SPI.
~5P15 is output to the OR circuit 155. The OR
The circuit 155 takes the logical sum of the servo synchronization signals SPI to 5P15 and the servo synchronization signal SPO of the falling differential waveform, and generates the servo synchronization signal SPn (n = 0.1. = 1
5) is output to the timer (TM2) 156. As shown in FIG. 4, the timer 156 generates a sample at timings Ta and Tb from the servo synchronization signal SPn.

b sample signal is output to the ADC 7. FIG. 5 shows the servo information writing area recorded on the servo disk 4a, with 5Do-SD15 for each track.
Servo information is recorded at 16 locations.

According to the above configuration, the spindle index signal ID
When X is input to the sample timing generation circuit 10,
As shown in FIG. 4, the servo synchronization signal SPn is generated 16 times during one revolution of the spindle motor 2 at intervals of T/16, and from this servo pattern synchronization signal SPn Ta, Tb
The a sample and b sample signals are output from the sample timing generation circuit to the ADC 7 at the timing of , and the servo data waveform amplified by the read amplifier circuit 6a is converted to a digital signal and sent to the μCPU as output voltages VQ and Vb.
It is input to I. As a result, μCPUI is (Va −V
b), the amount of track deviation is calculated, and the amount of track position correction, which is a digital value, is obtained.

The calculated track position correction amount is input to the DAC 15, where it is converted from a digital value to an analog value, and further input to the servo circuit 14, where it is sent to the access motor 1.
1, the servo head 5a and data head 5b are positioned.

(Problems to be Solved by the Invention) However, in the device with the above configuration, the servo synchronization signal S
PO to 5P15 are started by the spindle index signal IDX and are generated by the timer 154 that generates pulses at a fixed cycle of T/1B, so the spindle index signal IDX is generated at a constant speed with a fairly high precision for one revolution of the spindle motor 2. Even if controlled, if a temperature drift of the spindle index sensor 8 or the like causes a deviation relative to the servo patterns a and b, which are recorded and arranged on the servo disk 4a, sample a will result.

There was a problem in that the b sample signal fluctuated and samples of servo patterns a and b were not performed correctly.

FIG. 6 shows an example of a case where the servo putter cannot be read correctly because the spindle index signal IDX is deviated. One possible solution to this problem is to make servo patterns a and b sufficiently wide to accommodate fluctuations in the a and b sample signals, but after sampling servo patterns a and b, the next sample of servo pattern a can be Before this, it is necessary to calculate the sample voltage using the μCPUI, and therefore there is a problem in that it is not possible to obtain a sufficiently wide range.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a magnetic disk drive device that can perform head positioning with high precision without being affected by temperature drift or the like.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a magnetic disk drive device that samples servo patterns arranged on a disk surface and determines the head position. Means for detecting a limit value of deviation from a sample signal for detecting a servo pattern by changing the timing of the sample signal, and calculating and presetting an appropriate timing position of the sample signal from the limit value. and means for correcting the timing position of the sample signal.

(Function) According to the present invention, by changing the sample signal for detecting the servo pattern, the limit value of the deviation between the servo pattern and the sample signal is detected, thereby detecting the appropriate timing position of the sample signal. Therefore, the position of the head can be determined by correcting the preset timing position and detecting the servo pattern.

(Embodiment) FIG. 1 is a block diagram of a device circuit showing an embodiment of the present invention, in which a servo head 5a positioned by an access motor 11 connected to an encoder 12 controls a servo rotated by a spindle motor 2. surface disc 4a
The operations of reading the above servo information, performing accurate positioning, and reading and writing information on the data surface disk 4b using the data head 5b are the same as those explained in detail in FIG. 2, and have the same configuration. are represented by the same symbols.

The sample timing generation circuit 16 for reading servo patterns a and b contains the servo pattern waveform read from the servo controller 5a and amplified by the read amplifier circuit 6a, and the spindle index output from the waveform shaping amplifier circuit 9. Signal IDX is input. Also, the output is ADC as a and b sample signals? Output to. Furthermore, it is also connected to the μCPU 1 for setting preload data of the timer constituting the sample timing generation circuit 16 and reading timer values.

Here, the operation of the sample timing generation circuit 16 will be explained in detail with reference to FIG.

A is a signal differentiated by the fall of the spindle index signal IDX, and the signal A causes the register (Rgl) to be
The data Dα stored in the timer 160 is loaded into the timer 154, the timer operation starts, and the servo synchronization signal SP0 is output ta after the signal A. Therefore, by changing the data Dα in the register 160, ta becomes variable. The servo synchronization signal SPO is transmitted to the register 161 and the timer 156.
is input. The data Dβ stored in the register 161 is loaded into the timer 154 by this servo synchronization signal SPO, the timer operation is restarted, and the servo synchronization signal SPI is outputted from the timer 154 after tl. At this time t
Data Dβ is set so that β becomes to-tl+ΔtO if ta-to+ΔtO. Next, data Dβ is stored in the register 161, and the data D is loaded into the timer 154 by the servo synchronization signal SP1 to start the timer 154, and the servo synchronization signal SPn (n-2, 3 ...15) is timer 154
The timer 156 outputs a sample and b sample signals after ta and tb from the input servo synchronization signal SPn.

A method of detecting the corresponding variation of the spindle index signal IDX and the servo patterns a and b using the above configuration will be described.

In Fig. 8, initial tα-10, 1β-tl -T/1B
(t is one rotation period of the spindle) and sample signals a and b are located at the center of servo patterns a and b. The amount of fluctuation is detected using the spindle index signal I.
Servo synchronization signal SPO and servo pattern a immediately after DX,
Detection is performed using the relative relationship with b. ta-tO
When +ΔtO1tβ+ΔtO and the value of ΔtO is made variable, the a and b sample signals synchronized with SPO of the servo synchronization signal become variable, but the servo synchronization signal SP1 and above do not change. Here, as Δ10 is increased, the servo pattern reading voltage vb becomes smaller, so the a and b sample signals deviate from the servo patterns a and b. Conversely, when ΔtO is made smaller, Va becomes smaller and the a-sample signal is deviated.

From these values of ΔtO, an appropriate ta can be determined so that the a and b sample signals are located at the center of the servo pattern. 16 servo pattern samples per rotation
One time is used for detecting the amount of variation, and the remaining 15 times are used for information for positioning the head. △t
Since the value of O is changed once per revolution of the spindle motor 2, the above operation is performed over a plurality of revolutions.

As described above, in this embodiment, the spindle index signal ID in the servo pattern sample timing generation circuit is
For the sake of convenience, we have explained how to detect the amount of variation in X and correct the sample signal by installing a timer outside the μCPUI. However, it goes without saying that most of the circuits described above can be realized with a μCPU that has a built-in timer. . Also,
If the amount of deviation of the head position with respect to the track is large, the output waveform of servo pattern a or b becomes very small, making it inaccurate to detect the amount of variation in spindle index signal IDX.
This can be avoided by considering the condition that the values of a and Vb are greater than a certain value.

(Effects of the Invention) As described above, according to the present invention, a servo pattern and the servo pattern are detected in a magnetic disk drive device that samples a servo pattern arranged on a disk surface and determines the head position. means for detecting a limit value of deviation from a sample signal by changing the timing of the sample signal, and calculating an appropriate timing position of the sample signal from the limit value, Since a means for correcting the timing position of the signal is provided, the timing of the sample signal for detecting the servo pattern is changed, and the limit value of the deviation between the servo pattern and the sample signal is detected, and the appropriate position of the sample signal is always detected. By calculating this, it is possible to correct the timing of the sample signal, and as a result, the servo pattern can be sampled correctly without being affected by temperature drift, etc., making it possible to position the head with extremely high precision in a magnetic disk drive device. It has the advantage of being able to provide

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a magnetic disk drive device according to the present invention, FIG. 2 is a block diagram showing a conventional magnetic disk drive device, FIG. 3 is a block diagram showing a conventional sample timing generation circuit, and FIG. 4 is a block diagram showing a conventional magnetic disk drive device. A waveform diagram showing the relationship between the servo information output voltage and the sample timing waveform. Figure 5 is a diagram schematically showing the servo information writing area on the servo surface disk. Figure 6 is the servo information when the spindle index signal is shifted. FIG. 7 is a block diagram showing the sample timing generation circuit according to the present invention, and FIG. 8 is a waveform diagram showing the output waveforms of each part of the sample timing generation circuit according to the present invention. be. In the figure, 1... microcomputer (μCPU), 2
... Spindle motor, 3... Spindle motor drive unit, 4a... Servo disk, 4b... Data disk, 5a... Servo head, 5b... Data head, 6a... Read Amplifier circuit, 6b... Read/write amplifier circuit, 7... Analog-digital converter, 8... Spindle index sensor, 9...
・Amplifier circuit, 10, 1δ... Sample timing generation circuit, 11... Access morph, 12... Encoder, 13... Waveform shaping circuit, 14... Servo circuit, 15... Digicrew analog converter. Patent Applicant Oki Electric Industry Co., Ltd. Agent Patent Attorney Yoshi 1) Sei Takashi Figure 5

Claims (1)

[Scope of Claims] In a magnetic disk drive device that samples a servo pattern arranged on a disk surface to determine the head position, there is provided a limit value of the deviation between a servo pattern and a sample signal for detecting the servo pattern. means for detecting by changing the timing of the sample signal; and means for calculating an appropriate timing position of the sample signal from the limit value and correcting a preset timing position of the sample signal. A magnetic disk drive device characterized by: