JPH01303679A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent the excessive temperature rise of a coil by detecting the temperature of the coil of a voice coil motor by a temperature sensor, switching a speed profile when the coil temperature is high and reducing a current flowing in the coil. CONSTITUTION:A switching circuit 14 outputs a speed profile selecting signal 15 to select one of two kinds of speed profiles stored in a read only memory 16 by a temperature sensor output signal 12 and a seeking mode signal 13. Then, when the temperature of a coil of a voice coil motor rises and the level of the temperature output signal 12 outputted from a temperature sensor 11 becomes high, the speed profile selecting signal 15 to select the second speed profile of which current flowing in the coil of the voice coil motor is little is outputted. Then, the read only memory 16 refers to the second speed profile and outputs a digital speed reference signal 36 based on a difference signal 34. Thus, the excessive rise of the coil temperature can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device with an improved positioning circuit for a magnetic head that controls the moving speed of the magnetic head to move it to a target track during a seek.

[Prior Art] In a magnetic disk drive, a magnetic head moves to a target track based on a speed control mode, and after reaching the target track, is held on the target track based on a position control mode.

This magnetic head is driven by a voice coil motor,
Further, this voice coil motor generates torque when the output current of the power amplifier flows therethrough. In the speed control mode, when accelerating the magnetic head, the power amplifier is saturated and the magnetic head is accelerated at maximum acceleration, while when decelerating, it is controlled by a speed reference signal and is decelerated in accordance with this speed reference signal.

FIG. 3 is a block diagram showing a conventional speed reference signal generating circuit of this type for controlling the moving speed of a magnetic head.

The difference counter 33 inputs a preset signal 31 and a track pulse signal 32 output from a positioning control circuit (not shown), and outputs a difference signal 34.
This is a counter that outputs .

Read-only memory 35 is difference signal 3
4 and outputs a digital speed reference signal 36 corresponding to the difference signal 34 by referring to a stored predetermined speed profile. Further, the digital-to-analog converter 37 is a converter that inputs the digital speed reference signal 36, performs digital-to-analog conversion, and outputs an analog speed reference signal 38.

Next, the operation of the conventional speed reference signal generation circuit having the above-described configuration will be explained.

The difference counter 33 calculates the difference in the number of tracks between the track on which the magnetic head (not shown) is currently positioned and the target track on which the magnetic head (not shown) is positioned next, based on the input preset signal 31 and track pulse signal 32. is counted, and a difference signal 34 based on the difference in one Herak number is output. That is, the difference in the number of tracks is subtracted each time the magnetic head approaches the target track by one track, and becomes zero when the magnetic head reaches the position of the target track. At this time, the difference counter 33 successively outputs a difference signal 34 having information based on the difference in the number of tracks.

The read-only memory 35 inputs the difference signal 34 sequentially output from the difference counter 33 and refers to a predetermined speed profile, thereby generating a digital speed reference signal corresponding to the difference signal 34. Outputs 36. A digital-to-analog converter 37 performs digital-to-analog conversion on this digital speed reference signal 36 and outputs an analog speed reference signal 38 for controlling the moving speed of the magnetic head.

[Problems to be Solved by the Invention] However, in the conventional speed reference signal generation circuit described above, a fixed speed profile is used for accessing the magnetic head. Therefore, when a seek is performed at a short time interval, the temperature of the coil of the voice coil motor that drives the magnetic head increases excessively, which has the disadvantage of accelerating deterioration of the coil.

The present invention has been made in view of such problems, and includes:
An object of the present invention is to provide a magnetic disk device that can suppress excessive temperature rise in the coil of a voice coil motor and effectively prevent accelerated deterioration of the coil when a magnetic head seeks.

[Means for Solving the Problems] A magnetic disk device according to the present invention includes a difference counter that inputs a preset signal and a track pulse signal output from a positioning control circuit and outputs a difference signal, and a first speed control circuit. and a lead/lead which stores a profile and a second speed profile having a lower current than the first speed profile, and outputs a digital speed reference signal corresponding to the difference signal by referring to either the first speed profile or the second speed profile. an only memory, a digital-to-analog converter that converts the digital speed reference signal into an analog speed reference signal, a temperature sensor that detects the temperature of a coil of a voice coil motor and outputs a temperature sensor output signal, and the temperature sensor. inputting an output signal and a seek mode signal and outputting a speed profile selection signal to select one of the first or second speed profiles stored in the read-only memory based on the temperature of the coil; a read-only memory switching circuit, and one feature of the read-only memory is to switch the speed profile to be referenced based on the speed profile selection signal.

[Operation] According to the present invention configured as described above, when performing a seek of the magnetic head, the seek mode signal is set to read/write.
Input to the only memory switching circuit. At this time, when the temperature of the coil of the voice coil motor increases by 1 and the level of the temperature output signal output from the temperature sensor increases,
The read-only memory switching circuit outputs a speed profile selection signal for selecting a second speed profile in which less current flows through the coil of the voice coil motor.

When the read-only memory receives a speed profile selection signal for selecting this second speed profile, it refers to the stored second speed profile and generates a digital speed reference signal based on the difference signal. Output. The digital-to-analog converter performs digital-to-analog conversion on this digital speed reference signal and outputs a low-level analog speed reference signal. As a result, the effective value of the current flowing through the coil of the voice coil motor becomes small, and therefore, an excessive rise in coil temperature can be prevented.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a speed reference signal generation circuit constituting an apparatus according to an embodiment of the present invention. Components that are the same as those in FIG. 3 are designated by the same reference numerals, and their explanations will be omitted.

The temperature sensor 11 is disposed near a coil (not shown) of a voice coil motor, and is a sensor that detects the temperature of the coil and outputs a temperature sensor output signal 12 having a level corresponding to the temperature. This temperature sensor output signal 12 is input to a read-only memory switching circuit 14.

A seek mode signal 13 is also input to this switching circuit 14 .

Based on the temperature sensor output signal 12 and the seek mode signal 13, the switching circuit 14 outputs a speed profile selection signal 15 for selecting one of two types of speed profiles stored in a read-only memory 16, which will be described later. .

FIG. 2 is a detailed circuit diagram of the read-only memory switching circuit 14. As shown in this figure, a reference voltage 21 (+Vn) corresponding to a reference temperature regarding the coil temperature is set in the read-only memory switching circuit 14, and the level of this reference voltage 21 (7VR) and the The level of the temperature sensor output signal 12 is compared with that of the temperature sensor output signal 12, and the speed profile selection signal 15 is output based on the comparison result.

That is, the voltage comparator 22 of the switching circuit 14 receives the reference voltage (+V
R) 21 and the temperature sensor output signal 12 and output these signals 21. ．． 12 levels are compared, and a voltage comparator output signal 23 based on the comparison result is output. D
The type flip-flop 24 inputs the voltage comparator output signal 23 as a data input signal and the seek mode signal 13 as a clock signal 7, and inputs the previous input signal 7 until the next pulse of the seek mode signal 13 is input. This delay circuit outputs the voltage comparator output signal 23 as the speed profile selection signal 15.

On the other hand, the read-only memory 16 has, in addition to the conventional speed profile (first speed profile),
This is a memory that stores a newly provided speed profile (second speed profile). This second speed profile is substantially a low speed speed profile, and when this second speed profile is selected, a current with a small effective value flows through the voice coil motor during seek. The read-only memory 16 inputs the speed profile selection signal 15 and the difference signal 34 and generates a digital speed reference signal 3 determined based on these signals.
Outputs 6.

Next, the operation of the apparatus of this embodiment having the above-described configuration will be explained.

When performing a seek with the magnetic head, a seek mode signal 13 is input to the read-only memory switching circuit 14 together with the temperature sensor output signal 12 output from the temperature sensor 11 . When the level of the temperature sensor output signal 12 is lower than the level of the reference voltage 21 (+V) set in the read-only memory switching circuit 14, that is, when the temperature of the coil of the voice coil motor is lower than the reference temperature. is the speed profile selection signal 15 corresponding to the level of the reference voltage from the read-only memory switching circuit 14.
is output, which causes read-only memory 1
6, the normal first speed profile is selected. As a result, normal movement speed control is performed on the magnetic head.

Also, the temperature of the voice coil motor coil increases,
The level of temperature sensor output signal 12 is the reference voltage (10 VR)
21, the read-only memory switching circuit 14 outputs a speed profile selection signal 15 corresponding to the level of the temperature sensor output signal 12.

That is, when the voltage level of the temperature sensor output signal 12 exceeds the level of the reference voltage 21 (+VR), the voltage comparator output signal 23 output from the voltage comparator 22 becomes high level.

When this high-level voltage comparator output signal 23 is input to the D-type flip-flop 24, the output of the D-type flip-flop 24 switches to high level in synchronization with the input of the seek mode signal 13, which is a clock signal. ,
A high-level speed profile selection signal 15 is output. When this high-level speed profile selection signal 15 is input to the read-only memory 16 together with the difference signal 34, the second speed profile for low speed control is selected, and this second speed profile is referred to. A digital speed reference signal 36 based on the difference signal 34 is determined and output. And digital
The analog converter 37 converts this digital speed reference signal 36 into
A digital-to-analog conversion is performed on the signal, and an analog speed reference signal 38 is output.

When this analog speed reference signal 38 is output, a current with a small effective value flows through the coil of the voice coil motor, so that excessive temperature rise in the coil can be effectively suppressed. Moreover, it is therefore possible to prevent acceleration of deterioration in the coil of the voice coil motor.

In the above embodiment, when a seek is started, the information of the voltage comparator output signal 23 outputted from the voltage comparator 22 at the time of starting the seek is changed to the next sequential seek mode signal 1.
It is held in the D type flip-flop 24 until 3 is input. Also, during seek, the D-type flip-flop 24 retains the information of the voltage comparator output signal 23 at the time of input of the previous seek mode signal 13 until the next seek mode signal 13 is input. . Therefore, when performing a seek, the temperature sensor signal 12
Even if a temporary sudden level fluctuation occurs and the level of the voltage comparator output signal 23 changes suddenly, this level fluctuation will not affect the movement speed control of the magnetic head. Therefore, since it is possible to prevent the speed profile from changing inadvertently during seek, stable movement speed control can be performed at all times.

[Effects of the Invention] As explained above, according to the present invention, the temperature of the coil of the voice coil motor is detected by the temperature sensor, and when the coil temperature is high, the read-only memory switching circuit switches the coil to read-only.・Since the current flowing through the coil is reduced by switching the speed profile stored in memory, excessive temperature rise in the coil can be prevented. Therefore, it is possible to effectively suppress the acceleration of deterioration in the coil of the voice coil motor.
A magnetic disk device with high reliability can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a speed reference signal generation circuit constituting an embodiment of the present invention, FIG. 2 is a circuit diagram of the read-only memory switching circuit shown in FIG. 1, and FIG. FIG. 2 is a block diagram of a reference signal generation circuit. 11; temperature sensor, 12; temperature sensor output signal, 13;
Seek mode signal, 14; Read-only memory switching circuit, 15; Speed profile selection signal, 16, 35
;Read-only memory, 21;Reference voltage, 22;
Voltage comparator, 23; Voltage comparator output signal, 24; D type flip-flop, 31; Preset signal, 32; Track pulse signal, 33; Difference counter, 3
4; Difference signal; 36; Digital speed reference signal; 37; Digital-to-analog converter; 38; Analog speed reference signal

Claims (1)

[Claims] (1) A difference counter that inputs a preset signal and a track pulse signal output from a positioning control circuit and outputs a difference signal, a first speed profile, and a second speed profile that has a smaller current than the first speed profile. a read-only memory in which a speed profile is stored and outputs a digital speed reference signal corresponding to the difference signal by referring to one of the first or second speed profile; and converting the digital speed reference signal into an analog speed reference signal. A digital-to-analog converter for converting the temperature, a temperature sensor for detecting the temperature of the coil of the voice coil motor and outputting a temperature sensor output signal, and a temperature sensor for inputting the temperature sensor output signal and the seek mode signal and based on the temperature of the coil. a read-only memory switching circuit that outputs a speed profile selection signal to select one of the first and second speed profiles stored in the read-only memory; A magnetic disk drive characterized in that the only memory switches a speed profile to be referred to based on the speed profile selection signal.