JPH02304779A - Head positioning control circuit for magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent a head, for which mechanical vibration is generated and positioning accuracy is lowered, from being used for seek operation by executing the seek operation by a specified magnetic head. CONSTITUTION:When another head is moved to another target track, from the state of presently selected, head and track, the seek operation is executed by the specified head so that the head can be switched to the target head near the target track and positioned to the target track. Accordingly, when only the performance of the seek operation by the specified head, namely, only a positioning time and the positioning accuracy can be exactly realized, seemingly the same performance of the seek operation can be achieved by any head. Thus, the head, for which the mechanical vibration is generated and the positioning accuracy is lowered when the seek operation is executed at high speed, can be prevented from being used for the seek operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a head positioning control circuit in a magnetic disk device.

[Conventional technology]

In conventional devices, the following two methods are used when performing a seek operation to move from a currently selected head and track to a target head and target track. The first method is to switch the currently selected head to the target head and then use this head to perform a seek operation in a speed control mode to move the target head to the target track. The second method is to perform a seek operation in speed control mode to move the head to the target track using the currently selected head, and then switch to the target head in position control mode to follow the target track. This is a method to make the person do the following. An example of a device related to this type of device is Japanese Patent Application Laid-Open No. 58-218078.

[Problem to be solved by the invention]

The above-mentioned conventional technology is based on the premise that high-speed, high-precision seek operations can be performed with the same performance in all heads. However, the head positioning mechanism of a magnetic disk drive has become less rigid due to its miniaturization and weight reduction, and the mechanical resonance frequency is not so high, and variations, particularly in the damping characteristics, occur. For this reason, when a high-speed seek operation is performed, there is a risk that some heads may cause mechanical vibrations and degrade positioning accuracy. Further, since the sector servo signal for positioning is minute, there is a possibility that the performance for reading it may differ depending on the mounting position of the head with respect to the disk surface, the theta direction, and position. For this reason, there is a problem in that all heads cannot perform seek operations with the same performance, that is, with the same head positioning time and head positioning accuracy. Of course, it would be possible to tune the performance of reading the center servo signal and the parameters of the seek operation control circuit depending on the head, but this is difficult in practice.

[Means to solve the problem]

To achieve the above objective, in the positioning control circuit of a magnetic disk device that positions the magnetic head to a track on the data surface using a sector servo method, the target magnetic head is moved from the currently selected magnetic head and track to the target track. After the seek operation in the speed control mode is performed only by a specific magnetic head, the switch is made to the target magnetic head in the position control mode in which the magnetic head is caused to follow the target track.

An object of the present invention is to enable seek operations to be performed with the same head positioning time and head positioning accuracy.

[Effect]

The head positioning control circuit of the magnetic disk device of the present invention causes a specific head to perform a seek operation when moving the target head from the currently selected head and track to the target track, and moves the target head in the vicinity of the target track. It operates to switch to the head and position it on the target track. Therefore, if only the performance of the seek operation, that is, the positioning time and positioning accuracy, of this particular head can be accurately achieved, it is possible to achieve the same seek operation performance with any head. Therefore, when performing a high-speed seek operation,
It is possible to avoid using a head for seek operation that excites mechanical vibrations and reduces positioning accuracy. Furthermore, the problem that the performance of reading sector servo signals for positioning differs depending on the theta direction and position of the mounting position of the head with respect to the disk surface, making it impossible to use the same control circuit, can be solved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the overall configuration of a head positioning control circuit of a magnetic disk device according to the present invention.

1 is a disk disk for magnetic recording, and each surface is divided into a plurality of fan-shaped sectors 2 at equal intervals for recording data signals. At the boundary of the sector, a sector servo signal section 3 is provided in which a sector servo signal for positioning the head at a specific position in the radial direction called a track is recorded in advance. This disk 1 is rotated at a constant rotation speed by a spindle motor (not shown). A magnetic head 4 floating above the disk is provided at a position facing the disk 1, and reads and writes data signals and servo signals from predetermined tracks. For this purpose, a head positioning control circuit is required that performs a seek operation for moving a predetermined head to a predetermined track and a following operation for positioning and stopping the head on that track. This control circuit may have various configurations, but here we will explain one using a microcomputer. In the present invention, a seek operation is performed by a specific magnetic head. For this reason, the head switching circuit 5. switches the currently selected magnetic head to this specific magnetic head and switches this specific magnetic head to the target head. A servo signal demodulation circuit 6 for generating a track number and position signal from the servo signal output from the head switching circuit 5. a microcomputer 7 that outputs an operation signal for positioning the head on a target track and a magnetic head switching signal while referring to the track number and position signal output from the servo signal demodulation circuit 6;
DA converter 8 which converts the operation signal from the microcomputer 7 into an analog signal. A power amplifier 9 that amplifies the operation signal from the DA converter 8 and converts it into a driving current. It consists of a voice coil motor 10 that moves the magnetic head 4 to a target track using a drive current from a power amplifier 9 and causes it to follow the track.

FIG. 2 specifically shows an example of the arrangement of the magnetic heads 4.

In the figure, the same reference numerals as in FIG. 1 indicate the same parts. 11 is a shaft of a spindle motor 13 that rotates the disks 1a to 1c. magnetic head 48
4f are attached to the tips of the arms 12a to 12d, respectively, and are arranged opposite to the disk 1, as shown in the figure. These arms are collectively attached to the voice coil motor 10. In order to fit the magnetic head into the narrow gap between the discs, the magnetic head 4c is attached to the tip of the arm 12b, and the magnetic head 4b is attached to the middle of the arm 12b. The same applies to the magnetic heads 4d and 4e. Therefore, even if each magnetic head is exactly the same, the mechanical resonance frequency, especially the damping coefficient, may differ depending on the mounting position on the arm. If the installation as shown in the figure is suitable, it is expected that the magnetic heads 4b, 4d, and 4f installed in the middle of the arm will be less likely to generate mechanical vibrations even during high-speed seek operations. be done.

FIG. 3 shows the operation when moving the magnetic head 4a of the disk disk 1a from the track position Tr1 to the target track position Tr2. The disk surface is the data signal section 1 of the servo signal sections 3al, 3a2...
It is divided into 4al, 14a2, . . . , and unique magnetic recording signals are read and written respectively.

The servo signal used for head positioning depends on the mounting direction of the magnetic head shown in Figure 2.

If a so-called azimuth angle occurs with respect to a straight line connecting the rotation center of the arm 12 and the magnetic head, a time lag occurs in the servo signal, so that the servo signal portion does not become radial. Therefore, if the magnetic head moves diagonally between tracks as shown in FIG. 3, the servo signal cannot be read accurately. Therefore, it is expected that a magnetic head with a small azimuth angle will be able to accurately read servo signals regardless of the theta direction or position even when performing a high-speed seek operation.

FIG. 4 is a flowchart showing the functions of the head switching circuit. In a state where the head is currently positioned on the current track, a request for a seek operation to position the target track and the target magnetic head is given to the microcomputer (see FIG. 1). microcomputer 7
First, a head switching signal is given to the head switching circuit 5 to switch the currently selected magnetic head to a specific magnetic head predetermined for the seek operation. Thereafter, the microcomputer 7 uses this particular magnetic head to perform a seek operation in the speed control mode up to the vicinity of the target track. When near the target track, the same specific magnetic head is used to position the target track in the position control mode. .

Here, the microcomputer 7 provides the head switching circuit 5 with a head switching signal for switching from a specific magnetic head to a target magnetic head. Thereafter, the microcomputer 7 uses this target magnetic head to perform a following operation on the target track.

〔Effect of the invention〕

According to the present invention, if it is possible to always achieve constant seek operation performance, that is, positioning time and positioning accuracy with a specific head, it is possible to achieve the same seek operation performance with any head.

Therefore, it is possible to avoid using a nearly unstable head for the seek operation, which would cause mechanical vibration to be excited and the positioning accuracy to deteriorate when performing a high-speed seek operation. In addition, the performance of reading sector servo signals for one positioning differs depending on the mounting position of the head with respect to the disk surface and the theta direction, and it has the effect of solving the problem that the same control circuit cannot be used.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a head positioning control device for a magnetic disk drive according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the arrangement of the magnetic head, and FIG. 3 is an explanatory diagram showing a seek operation. FIG. 4 is a flowchart showing the head switching operation. DESCRIPTION OF SYMBOLS 1...Disk disc, 2...Sector, 3...Sector servo signal section, 4...Magnetic head, 5...Head switching circuit, 6...Servo signal demodulation circuit, 7... Microcomputer, 8...DA converter, 9...Power amplifier, 10 Fig. 1

Claims (1)

[Claims] 1. In a magnetic disk device that positions a target magnetic head on a target track using a sector servo method, a specific magnetic head performs a seek operation in a speed control mode to move the target magnetic head to the target track from the selected magnetic head and track. What is claimed is: 1. A head positioning control circuit comprising: means for causing the magnetic head to follow the target track; and means for switching to the target magnetic head in a position control mode for causing the magnetic head to follow the target track.