JPH03219472A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To restrain the rise of a temperature causing off-track by adjusting access time length or an access interval so as to be long when the access interval by access instruction becomes short. CONSTITUTION:A magnetic head 5 is coupled to a carriage 7 and an access action is executed by supplying a current to a voice coil motor 8 from a power amplifier 9. A microcomputer 13 sends control instruction 11 such as acceleration or deceleration to an access control circuit 10. Besides, the computer 13 measures a time interval that the access instruction is sent from a host device. Thus, the level of an access frequency is decided. When it is detected by an access frequency measuring device that the access frequency becomes high, the access time per one access including a waiting time is made longer by an adjustment means and the access frequency is made low. Thus, since the rise of the temperature in a head/disk/assembly can be made small, the off-track caused by the rise of the temperature becomes small and malfunction is prevented from occurring.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic disk drive having a magnetic head positioning mechanism using a voice coil motor, and particularly relates to a magnetic disk drive having a control system that suppresses heat generated by magnetic head access. Regarding disk devices.

[Prior Art] Generally, in a magnetic disk device having a mechanism for positioning a magnetic head using a voice coil, the operation of positioning the magnetic head on a predetermined cylinder (track) of a magnetic disk is called an access operation (S E EK operation). . In order to perform the access operation reliably in a short time, acceleration and deceleration are controlled to follow a preset speed curve. Furthermore, a settling time is provided at the end of deceleration to suppress vibrations of the head and the like. A typical magnetic disk device takes a settling time of about 1 to 3+ns.

Acceleration and deceleration during access operations are performed by a voice coil motor (Voice Co11 M) from a power amplifier.

In large magnetic disk drives, a voice coil current of 6 to 8 A flows during acceleration and deceleration, and power of 180 to 320 W is applied to the voice coil. This current generates heat, and when the access frequency is high and the time interval is short, HD A (He
The temperature rise inside the ad Disk Assembly is 1
The temperature can reach over 5℃. This temperature increase generates an off-track component when the magnetic head performs a read/write operation on a track.

Therefore, in order to suppress this temperature rise, as a conventional technique, as shown in Japanese Patent Application Laid-Open No. 61-216175, the internal mechanism of the HDA is changed to forcibly air-cool the magnetic head positioning mechanism, thereby suppressing the temperature rise. How to prevent off-track by attaching a temperature sensor to the disk drive as shown in Japanese Patent Application Laid-open No. 61-220180, and when a sudden temperature change occurs, the positioning time interval value of the magnetic head positioning servo. A method is known in which accurate positioning correction is performed by reducing the size of the position.

[Problems to be Solved by the Invention] All of the above-mentioned conventional techniques can be implemented when there are no restrictions such as dimensional restrictions, but it is difficult to implement when there are restrictions on space or size. For example, in the conventional technology using the above-mentioned temperature sensor, a small and high-precision HDA
The temperature sensor needs to be installed in a narrow, sealed space of the head disk assembly, which is difficult to implement. Further, in the case of using a temperature sensor, there is a problem that the control mechanism becomes complicated and the cost increases.

Therefore, an object of the present invention is to solve the problems of the prior art described above, and to provide a microcomputer program that performs access control without being subject to size constraints, without the need to add parts such as temperature sensors to existing equipment, and without being subject to size constraints. It is an object of the present invention to provide a magnetic disk device that can be realized by using relatively simple means to prevent temperature rise in the HDA section, thereby preventing off-track.

[Means for Solving the Problems] In order to achieve the above object, the magnetic disk drive of the present invention uses an access command as a means for detecting a temperature rise that causes off-track without adding any parts such as a temperature sensor. We focused on the frequency of

The higher the access frequency, the higher the temperature rise.

In fact, high access frequency can be detected by measuring the time interval between successive access commands from the higher-level controller (the shorter the time interval between access commands, the higher the access frequency).

Therefore, in the present invention, a means (access frequency measuring device) is provided to measure the access time interval (for example, average access time interval) of successive access commands, and when this time interval becomes short, the subsequent actual Adjust access operations to lengthen the time required for each access, including waiting time, by adding a longer wait time during access, or to lengthen the time interval between successive accesses. A means (variable access time device) is provided.

This makes it possible to suppress the temperature rise of the HDA.

[Effect] The effect based on the above configuration will be explained.

The access frequency measuring means measures the time interval at which access commands are received from the host device. This determines whether the access frequency is high or low. The means for adjusting the access operation (variable access time device) varies the access time. That is, when the access frequency measuring device detects that the access frequency has become high, the adjusting means increases the access time per access including the waiting time and lowers the access frequency. Since the temperature rise within the HDA can be reduced, off-track due to temperature rise can be reduced, and malfunctions can be prevented.

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

FIG. 1 is a diagram showing an example of an access operation in terms of magnetic head speed and time. The speed of the magnetic head is first accelerated, and when it reaches the target speed □, it shifts to deceleration 2. In a magnetic disk drive, a deceleration curve is usually set and deceleration 2 is performed along the curve. A settling time 3 is provided at the end of the deceleration to allow vibrations of the magnetic head to subside. Accelerate more than
The three factors, deceleration and servicing time, are collectively called access time. A circuit configuration for implementing the present invention is shown in FIG. The magnetic head 5 is connected to a carriage 7,
The access operation is performed by supplying current from the power amplifier 9 to the voice coil motor 8. The μm computer 13 receives commands from a host device through a path line 14, an I/F (interface) circuit 15, and a path line 16, and sends control commands 11 such as acceleration and deceleration to the access control circuit 10. On the other hand, μm computer 1
3 receives the status signal 12 such as the end of deceleration from the access control circuit 10, calculates the settling time 3, etc., and issues an access completion report to the host device.

The present invention prevents the temperature rise within the HDA by changing the settling time (Ts) 3 using a μm computer program. The process will be explained below using the flowchart in FIG. 4 and an explanatory diagram (FIG. 3).

In FIG. 3, the vertical axis represents the magnetic head speed, and the horizontal axis represents time.

The access operation is repeated, and the time interval between each access operation is T1 to T. (='r,). The operating procedure will be explained with reference to FIG. Starting from 5TART 401, the N register is set to O (402). The N register indicates the number of accesses. Next, the N register is set to 0 (403).

The N register indicates the memory address where the access interval TN time is stored. Next, the process enters a state of waiting for an access command (404), and when an access command arrives, the process advances to the next step. The TN timer is a timer for measuring access intervals, and is turned off in this step (405).

Next, 1 is added to the N register (406). Next, the access interval TN measured by the TN timer is set to address N (407). The access operation is performed, and after a settling time (Ts) of 3 (408), the TN timer is set to N (410). Add 1 to N register (411)
, K is less than 10, the process returns to waiting for an access command. K is 10
(412), that is, when the access interval is measured 10 times, the average access time TA is calculated (413)
. When TA is less than 5 ms (414), the settling time Ts is set to 5 ms (415). 5ms to 10m
5, set T to 3ms (416) (416).
7).

If it is 10+++s or more (418), Ts is set to 1 ms (419). By controlling the settling time T8 using the above program routine, the access interval can be increased and temperature rise can be suppressed.

[Effects of the Invention] As explained in detail above, according to the present invention, the access interval between access commands is measured, and when this interval becomes shorter, the access time such as the access waiting time (settling time) becomes longer. Since the access interval is adjusted to be longer, there is no need to add a temperature sensor or its peripheral circuit to existing equipment, and the temperature rise that causes off-track can be suppressed.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the access operation of the magnetic head, Figure 2 is an explanatory diagram showing the access operation of the magnetic head.
3 is a diagram illustrating an access operation according to an embodiment of the present invention, and FIG. 4 is a flowchart illustrating an access operation according to an embodiment of the present invention. 1...Acceleration time, 2...Deceleration time, 3
......Settling time, 4...Spindle, 5...Magnetic head, 6...Magnetic disk, 7...Carriage, 8...Voice coil motor, 9...
... power amplifier, 10 ... access control circuit, 11 ... control command, 12 ... status signal, 13 ... microcomputer, 14.
16...pass line, 15...interface circuit. Fourth

Claims (1)

[Claims] 1. A magnetic head positioning mechanism that uses a voice coil motor to move the magnetic head and position it on a desired track;
In a magnetic disk drive having a control circuit that controls access by energizing the voice coil motor, means for measuring an access interval between successive accesses;
A magnetic disk drive comprising means for adjusting the access time length or access interval of subsequent accesses so that the shorter the measured access interval, the longer the access time length or access interval of subsequent accesses.