JPH0334152A - Flexible magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent the tracking performance of a head from lowering by supplying a clock signal for a format data signal generation circuit and a clock signal for the motor driving circuit of a motor which rotates a disk from a common clock signal generation circuit. CONSTITUTION:The clock signal generation circuit 101 supplies the clock signal which supplies the reference of time to the format data signal generation circuit 102 and the motor driving circuit 108. The format data signal generation circuit 102 receives the command of a system controller 103, and generates a format data signal to be written on the disk. The start timing of the format data signal is supplied with an index signal outputted from an index detection element 110. The index detection element 110 is mounted on the motor 107, and generates one index per one revolution of the disk 106, and supplies the start point of a track on the disk.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a flexible magnetic disk device used in various information devices, and more particularly to a flexible magnetic disk device having recording track following means using a sector servo system.

BACKGROUND OF THE INVENTION In recent years, flexible magnetic disks have been widely used as data files for various information devices.

However, while efforts have been made to reduce the size of disks and improve recording density, the formant used at the time of development, or one based on that formant, is still in use. This is because, unlike hard disk drives, flexible magnetic disk drives have the feature that the recording medium can be replaced, so the format used at the time of development was followed in consideration of data compatibility.

Initially, flexible magnetic disk devices used a belt-drive AC synchronous motor as rotational power for the disk. For this reason, it was not possible to expect very high rotation accuracy of the disk. Therefore, in the format of a flexible magnetic disk device, there is an area called Gap4 provided solely for absorbing the error in the number of rotations of the disk.

In other words, information recorded on a flexible magnetic disk device is managed in units called sectors, and sectors are recorded in order from the generation of an index signal, which is the starting point of disk rotation. The sum of the sectors and the intervals between the sectors recorded in is set to be shorter than the length of the l track at the normal rotational speed by the error in the rotational speed. This is to prevent the last sector from overwriting the first sector if the disk rotation speed is low when formatting the disk. The area from the end of this last sector to the start of the first sector is an area called Gap 4 (Figure 2 (a)).The amount of error in rotation speed is expected to be 2 to 2.5%. The size of Gap4 is set to absorb this (for example, Shoji Takahashi, "Latest floppy disk device and its application know-how", 1984 C
Q Publishing).

Problems to be Solved by the Invention As mentioned above, in flexible magnetic disk drives, as a result of the pursuit of miniaturization and improvement in recording density, a servo method was introduced that uses servo signals on the disk to position the magnetic head. reached. In this method, servo information is written on the disk, and when the head reads it, servo data that gives the relative positional relationship between the head and the track is obtained, and the head is positioned on the track based on this servo data. That is, a servo system for head tracking is provided. This allows the head to correctly trace the center of the track even if the track density increases.

In flexible magnetic disk drive devices, a sector servo method is used in which servo information that provides the relative positional relationship between the head and the track on the disk is arranged for each sector to prevent deformation of the disk or eccentricity of the disk due to disk replacement. used.

In the sector servo method, servo information is placed at the end of each sector. 2nd r! ! The timing at which servo data is obtained in the conventional format of J(a) is as follows. Servo data is obtained at regular intervals from generation of the index signal to the final sector. However, the next servo data of the last sector cannot be obtained unless you wait for the time corresponding to Gap4 and the first sector.
The interval between servo data before and after p4 is Ga compared to others.
It becomes longer by p4.

FIG. 3 shows this situation. Assuming that first-order eccentricity occurs on the disk, the tracks on the disk viewed from the head will appear to undulate in a sinusoidal manner at a period of once per rotation of the disk. This track undulation is sampled for each sector and obtained as servo data.

FIG. 3(a) shows a case where the sector intervals are equal. The track waviness is represented by a continuous sinusoidal line, and the servo data obtained for each sector is represented by a columnar bar graph. Figure 3 (c) is
This figure shows servo data obtained in a conventional format with Gap 4 under the same track waviness.

As shown in the figure, it can be seen that the sampling interval of servo data becomes longer before and after Gap4. In this part, the amount of change in the servo data is large.

On the other hand, the servo system has a sample value servo configuration in which servo data is obtained discretely.

For this reason, time within the servo system is not marked by actual time but by the arrival of servo data. In other words, the servo system is based on the premise that servo data can be obtained at regular intervals. When servo data as shown in FIG. 3(C) is provided, the servo system recognizes that track waviness as shown in FIG. 3(C) exists. As a result, in the servo system, in the process of following the distortion of the disk that does not exist in reality,
This causes unnecessary movement of the head, causing the head to deviate from the center of the track to be traced.

This causes deterioration in the quality of the reproduced signal output from the head, which in turn causes deterioration in the reliability of data recorded on the disk device.

The present invention has been made in view of the above-mentioned problems, and uses the configuration described below to eliminate the need for Gap 4, and as a result, the intervals at which servo data is obtained are brought closer to equal intervals, and the head due to the above-mentioned causes is prevented. The purpose of the present invention is to provide a flexible magnetic disk device that can avoid deterioration in tracking performance.

! Means for Solving Ia In order to solve the above problems, the flexible magnetic disk drive of the present invention includes a clock generating means and a format data generating means for generating a format data signal for the disk based on a clock signal outputted from the clock generating means. The clock generating means includes a clock generating means, and a disk driving means for rotating the disk based on a clock signal output from the clock generating means.

Effect of the Invention With the above-described configuration, the present invention can use a common time base for generating a disk format data signal and a time base for rotating the disk. As a result, the disk rotational speed error seen from the format data signal can be made to appear to be zero, and Ga
p4 becomes unnecessary.

Embodiment Hereinafter, an embodiment of the flexible magnetic disk device of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a flexible magnetic disk device of the present invention.

A clock signal generation circuit 101 supplies a clock signal that provides a time reference to the format data signal generation circuit 102 and the motor drive circuit 108.

The format data signal generation circuit 102 receives a command from the system controller 103 and generates a format data signal to be written on the disk. The start timing of the format data signal is determined by the index detection element 11.
It is given by the index signal which outputs 0. An index detection element 110 is attached to the motor 107 and generates an index signal once per rotation of the disk 106, providing the starting point of a track on the disk.

The format data signal is amplified by write amplifier 104 and written to disk 106 by head 105. The head 105 is positioned on a target track by a head positioning means (not shown).

A motor 107 that rotates the disk 106 is driven by a motor drive circuit 10B. Motor drive circuit 10
8 is to detect the rotational speed of the motor 107, that is, the disk 106, by the FC detection element 109, and to maintain this at a predetermined value.

By the way, as mentioned above, an AC synchronous motor using an AC power source was initially used as a motor for rotating the disk, but it requires a separate AC power source.
Due to the fact that the rotation speed depends on the power supply frequency (50 or 601 &) and efficiency, direct drive type brushless motors are often used these days.In AC synchronous motors, the rotation speed depends on the power supply frequency. Because they are synchronized, there was no need to control the rotation speed, but brushless motors require this to be provided separately. Therefore, the rotation speed of the motor is generally controlled by a method called the FC servo method.

In this method, first, the rotor of the motor is provided with a multi-pole structure, and an FC detection element is provided on the stator side of the motor. When the motor rotates, electricity V111! Due to the action of conduction, an electromotive force having a frequency corresponding to the rotation speed of the motor is generated in the FC detection element. The motor drive circuit compares the frequency of the signal from this FG detection element with a reference frequency corresponding to a predetermined motor rotation speed, and accelerates or decelerates the motor according to the result, thereby controlling the motor to a predetermined speed. It rotates at a rotation speed of . In this method, the accuracy of the rotational speed is ultimately determined by the accuracy of the reference frequency. Therefore, it is widely used in places where high-precision rotation is required.

However, in current flexible magnetic disk drives, the format itself does not require precision in the number of rotations of the disk, so an inexpensive ceramic oscillator or the like is used to generate the reference frequency. The total 95-frequency oscillator has lower frequency accuracy than a crystal oscillator, and is also more easily affected by temperature, etc., so the rotational accuracy of the disk is still about 2 to 2.5%.

On the other hand, in the flexible magnetic disk drive of the present invention, a clock signal common to the format data signal generation circuit that generates the format data signal is used as the signal that provides the reference for the rotation speed of the motor 107.
In the configuration of the present invention, if we consider a case where the frequency of the clock signal generated by the clock signal generation circuit 101 is slightly lower than a specified value, the format data signal generated by the format data signal generation circuit 102 has a frequency of the clock signal. is longer than the standard, so the entire length becomes longer. On the other hand, the rotation speed of the motor 107 decreases because the frequency of the clock signal supplied to the motor drive circuit 10B decreases. As a result, the physical recording pattern recorded on the disc will be the same as if the frequency of the clock signal were of a specified value.

Conversely, the same applies when the frequency of the clock signal generated by the clock signal generation circuit 101 is slightly higher than the specified value. In other words, even if the frequency of the clock signal changes, the final disc obtained is the same, only the process of writing the format data signal is different. This indicates that the error in the rotational speed of the disk as seen from the data on the disk is apparently zero.

Therefore, according to the configuration of the present invention, in the format of the flexible magnetic disk, Gap 4, which is provided in consideration of the rotational speed error, becomes unnecessary.

Therefore, as a format, a conventional format with Gap4 removed can be adopted.

Thereby, the track can be divided into sectors at equal intervals (FIG. 2(b)).

When the sector servo method is used, a servo signal is obtained at regular intervals (FIG. 3(a)), so that more accurate head positioning is possible.

Effects of the Invention As described above, in the flexible magnetic disk drive of the present invention, the clock signal for the format data signal generation circuit that generates the format data signal and the clock signal for the motor drive circuit of the motor that rotates the disk are connected to a common clock. By supplying the signal from the signal generation circuit, it is possible to synchronize the format data signal and the disk rotation. Gap 4 for absorbing errors in rotational speed is not required for the assembly and formatting, and the track can be divided into sectors at equal intervals. This is because when performing head positioning using the sector servo method, a servo signal is obtained at regular intervals, making it possible to position the head with higher precision.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the flexible magnetic disk of the present invention, and FIG. ! J is a format pattern diagram showing a conventional example and a format according to the present invention, and FIG. 3 is a waveform diagram showing the state of servo data obtained under first-order eccentricity. 101-----Clock signal generation circuit, 102...
...Format data signal generation circuit, 103...
...System controller, 104...Writing amplifier, 105...Head, 106...
...Disc, 107...Motor, 10B
...Motor drive circuit, 109...FC
Detection element, 110... Index detection element.

Claims (1)

[Claims] A flexible magnetic disk device having recording track following means using a sector servo system, comprising: a clock generation means; a format data generation means for generating a format data signal for the disk based on a clock signal output from the clock generation means; 1. A flexible magnetic disk device comprising: disk drive means for rotating the disk based on a clock signal output by the generation means.