JPH0411353A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce the power consumption by controlling a spindle motor to two kinds of rotational frequency and keeping the spindle motor in the state of the first rotational frequency at the time of recording and reproducing information or moving and positioning an actuator and reducing the rotational frequency at the time of waiting. CONSTITUTION:A spindle motor 12 is rotated with the first rotational frequency, and a magnetic head 13 is moved to a proper track by an actuator 14 to record and reproduce information. At the time of switching from the recording and reproducing state to the waiting state, a rotational frequency command 18 is so outputted that the spindle motor 12 is rotated with the second rotational frequency after the magnetic head 13 is positioned to the outside periphery of a magnetic disk 11, and a rotational frequency controller controls a driving current 16 to reduce the rotational frequency of the spindle motor 12. When recording and reproducing are necessary, the magnetic head 13 is positioned to a track required for recording and reproducing after the rotational frequency of the spindle motor 12 is changed to the first rotational frequency, that is, after the rotational frequency is increased. Thus, the power consumption is reduced.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a magnetic disk device for recording or reproducing information, and more particularly, to a magnetic disk device that saves electricity by changing the rotational speed of a spindle motor during standby. a.Conventional technology Conventional magnetic disk drives: -When the power is turned on,
Even if no information is recorded or played back, the rotation of the spindle motor is controlled to remain constant at, say, 3,600 RPM until the power is cut off. This invention has a function of shifting to a standby state and stopping rotation of the spindle motor if plate information is not recorded or reproduced at a predetermined time. In a magnetic disk drive that is in standby mode, when the spindle motor stops rotating, the air flow between the magnetic head and the magnetic disk is lost, and the buoyancy is lost, so the magnetic head does not come into contact with the magnetic disk. Immediately before and after startup, there is not enough airflow, so the magnetic head and magnetic disk are sliding around, increasing the possibility of dust particles being generated from these contact points and increasing the risk of head crash. A problem unique to magnetic disks is that frequently stopping the rotation of the spindle motor increases the probability of a magnetic head crash.

In addition, since the spindle motor is stopped, it takes time to bring the spindle motor up to a steady rotation speed to return from the standby state. A magnetic disk drive is configured as follows to solve the problems of conventional magnetic disk drives: a magnetic disk, a spindle motor that rotates the disk, and a device that records or reproduces information on the magnetic disk. a magnetic head for moving and positioning the magnetic head, an actuator for moving and positioning the magnetic head, and a rotation speed control device for controlling the spindle motor to at least two types of rotation speeds, a first and a second rotation speed, when recording and reproducing information, and moving the actuator. In the above-described structure, the spindle motor may be provided with command means for instructing to keep the spindle motor at a first rotational speed when positioning, and to keep the spindle motor at a second rotational speed when waiting. Since the L head does not come into contact with the disk during standby, there is less risk of a head crash.Also, by setting the second rotation speed lower than the first rotation speed, power saving can be achieved. Also, L when restarting
The time required to bring a stopped disk up to its normal rotational speed can be reduced compared to the conventional case. 1 is a basic block diagram of a first embodiment of a magnetic disk device of the present invention. In the figure, 11 is a magnetic disk; 12 is a spindle motor for rotating the magnetic disk; 13 is a magnetic head for recording or reproducing information on the magnetic disk;
14 is an actuator that moves and positions the magnetic head.
15 is a rotation speed control device that controls the spindle motor to at least two types of rotation speeds, first and second. 16 is a drive type in which the rotation speed control device drives the spindle motor! 17 is a command half that instructs the spindle motor to be kept at the first rotational speed and kept at the second rotational speed during standby when recording and reproducing information or when positioning the actuator.18 is a command when the command means rotates. 19 is a head position command that the command means outputs to the actuator; and 19 is a head position command that the command means outputs to the actuator.The operation of the above configuration will be explained as follows.The magnetic disk device of the present invention records and reproduces magnetic information. when,
The spindle motor 12 rotates at a first rotational speed, and the actuator 14 moves the magnetic head 13 to an appropriate track for recording and reproduction. This state is called the recording/playback state. When transitioning from the recording/playback state to the standby state,
First, the command means 17 outputs a head position command 19, and the actuator 14 positions the magnetic head 13 on the outer periphery of the magnetic disk 11.
The rotation speed control device controls the drive current 16 by outputting a rotation speed command 18 so that the spindle motor 12 rotates at a rotation speed of . When the need for recording and playback arises, the process of transitioning from the standby state to the recording and playback state occurs.
At this time, after changing the spindle motor 12 to the first rotation speed, that is, after increasing the rotation speed, the resistive magnetic head 1
Figure 2 is a flowchart showing the processing flow of this embodiment described above.Here, we will also discuss the flying height of the magnetic head above the magnetic disk surface. Figure 3 is an example of a characteristic diagram of the magnetic head position and flying height.The magnetic head of a magnetic disk drive is slightly floated by air flowing between it and the magnetic disk, and the flying height is If this flying height is large, the magnetic coupling between the magnetic head and the magnetic disk becomes weaker, and the read signal of the magnetic head becomes smaller, so there is a limit to increasing the recording density. If the height is lower than the minimum allowable height, there is a high probability that the magnetic head will come into contact with the magnetic disk when a disturbance occurs and the magnetic head vibrates, or when the magnetic head passes over unevenness on the magnetic disk. 4. This increases the possibility that the magnetic head will peel off components on the surface of the magnetic disk, causing a head crash in which the magnetic disk and magnetic head continue to make contact due to the generated dust particles and surface irregularities. Managing the flying height has a significant impact on the performance and reliability of magnetic disk drives. Therefore, even if the magnetic disk is rotating at the same rotation speed, the relative speed changes depending on the position of the magnetic head, and the flying height changes accordingly.However, it is also important to think about the flying height in the standby state. In this state, the second rotation speed is set lower than the first rotation speed for the purpose of power saving.If the position of the magnetic head is the same, the relative speed will be slow and the flying height is low. By positioning in the direction, the relative speed is increased and the flying height is maintained. - For example, the outermost track radius is 2 times the innermost track radius.
Even if we consider a magnetic disk device that is twice as large as the magnetic head, when the magnetic head is positioned on the innermost track in the recording/reproducing state, the relative speed is the slowest while maintaining the first rotational speed, and the flying height is also the lowest (the lowest force). When the flying height is maintained and the rotation speed decreases to the second rotation speed, if the magnetic head is located at the innermost circumference, the relative speed will be slower than in the recording/reproducing state, and the flying height will be lowered. The height may be lower than the minimum flying height. However, if the magnetic head is positioned at the outermost circumference, the radius will double, so the relative speed will also double. Therefore, the second rotation speed will be lower than the first rotation speed. number 2
The relative speed is the same as when the magnetic head is positioned at the innermost circumference during recording and playback, so the flying height is maintained at the minimum flying height, reducing the risk of head crash. Fig. 4 is a basic block diagram of a second embodiment of the magnetic disk device of the present invention.a The difference from the first embodiment is a command means, a magnetic head evacuation mechanism, and an evacuation command. Therefore, I will only explain this point. In the figure, 21 is a magnetic head evacuation device that moves the magnetic head a predetermined distance from the magnetic disk during standby. 22 is an evacuation command that the command means outputs to the magnetic head evacuation mechanism. When recording and reproducing, the magnetic head is not restricted by the magnetic head evacuation mechanism! When moving over the magnetic disk that is rotating at the first rotational speed, the magnetic head evacuation mechanism moves the magnetic head away from the magnetic disk in response to an evacuation command from the command means. The spindle motor rotates at the second rotation speed.4 With this configuration! Since there is no possibility of contact between the magnetic head and the magnetic disk, there is no problem with the flying height, and the selection range of the second rotation speed is wide. The magnetic head evacuation mechanism returns the magnetic head, and after these are completely separated, the magnetic head is positioned. Figure 5 shows the process flow of this embodiment described above. Figure 6 shows the elapsed time and rotational speed when the spindle motor is started. The time required to start the spindle up to rotational speed can be reduced compared to starting from a stopped spindle.

Effects of the Invention The magnetic disk drive of the present invention achieves the following excellent effects: (1) it achieves power savings in standby mode, and (2) it prevents head crashes even in standby mode. (3) The restart time may be shortened.

[Brief explanation of drawings]

Figure 1 shows the basic block of the first embodiment of the magnetic disk drive of the present invention. Figure 2 shows the flow of the process of the present invention. Figure 3 shows the relative speed and flying height of the magnetic head and magnetic disk. Fig. 4 shows the basic block diagram of the second embodiment of the present invention. Fig. 5 shows the process flow of the second embodiment. Fig. 6 shows the elapsed time when starting the spindle motor. This is a characteristic diagram showing the relationship with the rotation speed. 11...Magnetic disk drive 12...Spindle motor drive 13...Magnetic head 14...Actecoator 15...Rotation speed control device [16.・Driving electric power f, 17
...Command half composition 18.. Rotation speed command, 19.. Head position command, 21.. Magnetic head evacuation machine IL 2
2...Name of the agent to the evacuation finger Patent attorney Shigetaka Awano and 1 other person Suran Tisk Spindle Mo 9 Magnetic Hetado Acteco Etalo Table Number Discount Shino 2 Island 17III Moat 3b Seiko Throw 2nd Illustration ■Min Heut Ichiri J & Yasuko 6 VLrt Het Ll Sagi Kai 1jiP finger Q Sho 1 victory

Claims (3)

[Claims] (1) A magnetic disk, a spindle motor for rotating the disk, a magnetic head for recording or reproducing information on the magnetic disk, an actuator for moving and positioning the magnetic head, and at least two types of first and second types. A rotation speed control device that controls the spindle motor to a rotation speed, and maintains the spindle motor at a first rotation speed during information recording/reproduction or actuator positioning, and maintains the spindle motor at a second rotation speed during standby. A magnetic disk device comprising a command means for instructing a magnetic disk device to maintain the magnetic disk. (2) The command means is configured to actuate the actuator to position the magnetic head on the outer periphery of the magnetic disk during standby, and then issue a command to bring the spindle motor into the second rotational speed state. The magnetic disk device according to claim 1. (3) During standby, the command means operates a magnetic head retraction mechanism that moves the magnetic head a predetermined distance from the magnetic disk surface and retracts it, and then sets the spindle motor to a second rotational speed state. 2. The magnetic disk device according to claim 1, wherein the magnetic disk device is configured to give a command.