JPS63292453A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To increase a head floating amt. more than a specific value and to decrease a period of high probability of trouble occurrence and also to improve reliability by raising the number of revolutions of a motor by a signal from a host device at the time of non-operation of recording and reproducing. CONSTITUTION:A disk plate 2 fixed to a spindle shaft 1 is driven by a DC motor 3. The motor is kept at a specific number of revolutions by a motor control circuit 5 with a revolution signal 4 from a number of revolution detecting element built in the motor 3. When an instruction 6 from the host device is decoded via an interface circuit 7 and an instruction decoder 8 into a raising instruction 9, the number of revolutions of the motor is raised up to the appointed number of revolutions by the control circuit 5. If a number of revolution lowering instruction 10 is decoded, the motor is brought back to its specific number of revolutions again. By this constituting method, on completion of a job, the number of revolutions is raised up to increase the floating amt. of the head so that the incidence of trouble is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control system for a DC motor for rotationally driving a magnetic disk plate.

[Conventional technology]

Conventionally, this type of rotational drive mechanism has kept the rotational speed of the disk plate constant.

[Problem that the invention seeks to solve]

As the performance of magnetic disk drives increases, the flying height of the magnetic head decreases, and during long-term operation, the disk plate and magnetic head may come into contact with each other due to the influence of dust, causing trouble. Since magnetic disk drives always maintain a constant flying height, the distance between the disk plate and the magnetic head always remains very small, which has the disadvantage that the probability of trouble occurring is relatively high.

[Means for solving problems]

The magnetic disk device of the present invention has a mechanism for rotating a disk plate by a DC motor whose rotation speed is controlled by a control circuit, and is characterized in that the rotation speed of the motor is increased when no recording or reproduction is performed on the disk. shall be.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention.

A disk plate 2 fixed to a spindle shaft 1 is driven by a DC motor 3 directly connected to one end of the spindle shaft 1. A motor control circuit 5 monitors a rotational speed signal 4 from a Hall element for detecting the rotational speed provided inside the DC motor 3 and controls the motor to maintain a specified rotational speed.

The command 6 from the host device is decoded by the command decoder 8 via the interface circuit 7, but when the rotation speed increase command 9 is decoded, it is sent to the motor control circuit 5, and the motor control circuit 5 determines the motor rotation speed in advance. Increase the rotation speed to the specified number.

In this state, when the rotational speed lowering command lO is decoded, the motor control circuit 5 operates to rotate the motor at the normal rotational speed again. The head 11 on the rotating disk plate flies above the disk plate with a small distance maintained due to the action of airflow on the surface of the disk plate as it rotates, but as the number of rotations of the disk plate increases, the force pushing up the head becomes stronger. The floating amount increases. Therefore, in the present invention, it is possible to control the flying height of the head to be larger than a specified value by a command from a host device.

In this way, in this embodiment, it is possible to control the flying height of the head to be larger than a specified value by a command from the host device, so that the rotation speed increases when a series of jibes for the magnetic disk device are completed. By increasing the flying height of the head with a command and controlling it from the host device so that it returns to the normal flying height with a command to lower the rotation speed when the next job starts, it shortens the period when the flying height is small and the probability of trouble occurring is high. It becomes possible to do so.

Next, a second embodiment of the present invention will be described.

Referring to FIG. 2, the integrating circuit 26 monitors the select signal 28 sent from the host device via the interface circuit 7, and starts a prescribed integrating operation when the select signal 28 becomes inactive. The output of the integrating circuit 26 is sent to the motor control circuit 5 as a rotation speed control signal 29, and the motor control circuit 5 receives this and increases the rotation speed of the motor in proportion to the rotation speed control signal up to a preset upper limit rotation speed. to rise. When a select signal is received from the host device, the integral circuit is immediately reset and the motor control circuit returns the motor to its normal rotation speed. In this example, the upper limit rotation speed is set to 2
The integral constant is selected so that the increase is 0% and the upper limit is reached in 10 minutes.

The magnetic helad 11 on the rotating disk plate floats above the disk plate with a small distance maintained due to the effect of airflow on the disk plate surface, but as the rotation speed of the disk plate increases, the force pushing up the head becomes stronger, causing the head to float. The amount becomes larger. Further, accesses from the host device are normally executed continuously, and when there is no access for several minutes, it can be determined that the series of jobs has finished.

Therefore, according to the present invention, it is possible to increase the rotational speed of the motor of a disk device that is left unused for a long time after the completion of zipping, and to maintain a large flying height of the head.

Next, a third embodiment of the present invention will be described.

Referring to FIG. 3, the timer circuit 36 receives a select signal 3B sent from the host device via the interface circuit 7.
is monitored, and when the select signal 38 becomes inactive, the time measuring operation is started. When the timer circuit 36 counts up to a preset time, it sends a rotation speed increase signal 39 to the motor control circuit 5, and the motor control circuit 5 receives this and increases the rotation speed of the motor to the preset rotation speed. raise. If a select signal is received from the host device in this state, the timer circuit is immediately reset and the motor control circuit returns the motor to its normal rotation speed.

[Effects of the Invention] As explained above, the present invention makes it possible to increase the flying height of the head of a magnetic disk device when no recording or reproduction is performed, which increases the flying height. This makes it possible to shorten the period in which the probability of occurrence of a small problem is relatively high, and has the effect of realizing a highly reliable magnetic disk device.

[Brief explanation of drawings]

1, 2, and 3 are block diagrams showing the configurations of first, second, and third embodiments of the present invention.

Claims (3)

[Claims] (1) It is characterized by having a mechanism for rotating a disk by a motor whose rotation speed is controlled by a control circuit, and means for increasing the rotation speed of the motor when no recording or reproduction is performed on the disk. Magnetic disk device. (2) The magnetic disk device according to claim (1), wherein the rotational speed of the motor is increased by a command from a host device. (3) Claim No. 1, wherein the increase in the rotational speed of the motor is performed by a timer that detects that access from a host device has been interrupted for a predetermined period of time.
The magnetic disk device described in section.