JP3863081B2 - Disk apparatus and head unload control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disk apparatus employing a ramp load mechanism for retracting a head for reading and writing signals from / to a disk-shaped storage medium at a fixed position outside the storage medium, and a head / unload control method thereof.
[0002]
[Prior art]
In a disk device such as a hard disk drive that employs a ramp loading mechanism, there are two methods for retracting (unloading) the head onto the ramp, control unloading and emergency unloading.
[0003]
The control / unload means that the hard disk drive is supplied with power and is unloaded under the control of the CPU (firmware). This uses the back electromotive force generated from the voice coil motor (VCM) of the head to optimally control the speed of the head during unloading so that the head can be safely and reliably retracted onto the ramp. .
[0004]
On the other hand, emergency unloading is a function for forcibly retracting the head onto the lamp because the control by the CPU (firmware) cannot be executed when the power supply to the hard disk drive is cut off. This is because the electric charge is stored in the hard disk drive and this electric charge is forcibly released to the voice coil motor (VCM) or the back electromotive force generated by the rotation of the spindle motor (SPM) in the hard disk is used. The head is retracted onto the lamp by flowing the electric charge due to the counter electromotive force to the voice coil motor (VCM).
[0005]
Here we focus on control during control / unload.
[0006]
FIG. 4 is a diagram showing the positional relationship of the head, media, and lamp during control / unloading from the side, and FIG. 5 is a diagram showing changes in the current flowing through the voice coil motor (VCM).
[0007]
The control / unload operation is performed, for example, by the following procedure. The numbers in parentheses in the following description correspond to the respective steps in FIGS.
[0008]
(1) Recognize the control / unload command.
[0009]
(2) The head (slider) 31 is caused to seek to a specific cylinder on the medium 32, and unloading is started from there to the outer peripheral side (the lamp 33 side).
[0010]
(3) Current is passed through the voice coil motor (VCM) until the head 31 reaches the target speed. At this point, the head 31 is on the medium 32.
[0011]
(4) The current flowing through the voice coil motor (VCM) 8 is controlled while monitoring the back electromotive force of the voice coil motor (VCM) so that the speed of the head 31 is maintained at the target speed. At this time, the head 31 is still on the medium 32.
[0012]
(5) The head 31 reaches the ramp outlet (the end on the medium side), and the tab 34 starts to rise up the slope 33 a of the ramp 33.
[0013]
(6) By riding on the ramp 33, the speed of the head 31 decreases.
[0014]
(7) Feedback by monitoring the back electromotive force of the voice coil motor (VCM) works to increase the current flowing through the voice coil motor (VCM).
[0015]
(8) When the head 31 finishes climbing the ramp throat slope 33a, the ramp 33 becomes a flat surface or a gentle downhill, so the speed of the head 31 increases.
[0016]
(9) Feedback by monitoring the back electromotive force of the voice coil motor (VCM) works to reduce the current flowing to the VCM.
[0017]
(10) The tab 34 of the head 31 collides with the outer stopper 35 and reaches the home position (final position) of the ramp 33.
[0018]
(11) A maximum current is applied to the voice coil motor (VCM) so that the head 31 is prevented from bouncing off by the stopper 35, and the head 31 is pressed against the outer stopper 35.
[0019]
(12) The head 31 is stopped at the home position of the lamp 33.
[0020]
[Problems to be solved by the invention]
However, in the above-described prior art, there is a difference in the influence of external force (friction force, offset force, etc.) that is applied when the head rides on the ramp depending on the usage environment of the hard disk drive, and there is a case where unloading in the optimum state is not achieved. .
[0021]
Specific phenomena that can occur include the following.
[0022]
・ External forces such as friction force acting between the tab of the head and the sliding surface of the ramp, offset force of the flexible printed circuit board (FPC), shaft loss of the pivot bearing of the head suspension assembly (HSA), etc. The head unload speed is significantly reduced, the speed becomes zero, and the head stops completely on the ramp.
[0023]
・ Even if the current flowing through the voice coil motor (VCM) is increased, the torque generated by the voice coil motor (VCM) cannot exceed the external force such as the frictional force, and the head can go up the slope of the ramp. Can not.
[0024]
-If it takes time for the head to stop on the ramp and start moving again, the unloading control will end, and the head will stop in the middle of the ramp before returning to the home position.
[0025]
・ If the external force such as friction force is smaller than expected, the target speed is set higher than necessary, so the impact that the head receives when it collides with the stopper also increases, shortening the life of the head. .
[0026]
The present invention has been made to solve the above problems, and provides a disk device capable of optimally controlling the head unloading operation according to the environmental temperature and a head unloading control method therefor. With the goal.
[0027]
[Means for Solving the Problems]
In order to achieve the above object, a disk device according to the present invention includes a head unit on which an element for reading a signal from a disk-shaped storage medium is mounted, and the head unit is supported at one end and moved relative to the storage medium. A head actuator, a motor for driving the head actuator, a lamp for localizing the head unit moved to the outer periphery of the storage medium by the head actuator at a predetermined retracted position separated from the storage medium, and a temperature. An optimal target speed for moving the head unit to the predetermined retracted position is set according to the sensor to be detected and the temperature detected by the sensor, and the head unit is moved to the predetermined target speed at the set target speed. And a control means for controlling the motor so as to move to the retracted position.
[0028]
According to the present invention, it is possible to suppress the fluctuation of the head unload speed due to the environmental temperature by setting the optimum target speed of the head unload with respect to the environmental temperature. As a result, it is possible to prevent head unloading errors in a low temperature environment, and to suppress the occurrence of an accident such as head damage due to a collision between the head and the stopper at a high temperature.
[0029]
Further, in the disk device of the present invention, the control means monitors the moving speed of the head unit, and the moving speed of the head unit, which is the monitoring result, and an optimum target speed set according to the temperature, May be obtained, and the supply current of the motor may be controlled based on the difference.
[0030]
According to this, high-precision head unload speed control becomes possible by speed feedback.
[0031]
In the disk apparatus of the present invention, the control means obtains a difference between the temperature detected by the sensor and a reference temperature in a predetermined temperature range, and sets an optimum target speed according to the obtained temperature difference. It may be set.
[0032]
Furthermore, in the disk apparatus of the present invention, the control means may calculate an optimum target speed based on a predetermined calculation formula using the temperature detected by the sensor and a reference temperature as variables. As a result, head unload speed control with higher resolution becomes possible.
[0033]
In this way, high-precision head unload speed control by speed feedback and head unload speed control by high resolution prevent head unload error and prevent head damage due to collision between the head and stopper. The effect can be further enhanced.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0035]
FIG. 1 is a perspective view showing a configuration of a hard disk drive which is an embodiment to which a disk device of the present invention is applied.
[0036]
As shown in the figure, the hard disk drive 1 includes a rectangular box-shaped case 2 having an open top surface, and a top cover (not shown) that is screwed to the case with a plurality of screws and closes the top surface of the case 2. It has.
[0037]
In the case 2, there are, for example, two disks (platters) 3 which are disk-shaped storage media, a spindle motor (SPM) 4 as a disk drive mechanism for supporting and rotating the disks 3, and a head actuator 6. Has been placed. Here, for example, a platter having a diameter of 65 mm (2.5 inches) and having magnetic recording layers on both sides is employed for the disk 3.
[0038]
The head actuator 6 includes a magnetic head slider 5 on which a head, which is an element for reading and writing signals on the disk 3, and a suspension 5a having a tab 9a that slides on a ramp 9 described later, and a suspension 5a at the tip. A carriage configured by stacking a plurality of head arm assemblies 15 including supported arms 7, and a bearing that rotatably supports the carriage with respect to a bearing shaft 13 erected vertically on the bottom wall of the case 2. It is comprised with the unit 12. FIG.
[0039]
Further, in the case 2, when the voice coil motor (VCM) 8 for driving the head actuator 6 and the magnetic head slider 5 are moved to the outer peripheral portion of the disk 3, they slide with the tabs 9 a to move the head to the disk 3. A board unit 10 on which a lamp 9 to be held at a predetermined retreat position separated from the head and a head driver IC and the like are mounted is accommodated.
[0040]
Further, on the back side of the component housing portion of the case 2, a spindle motor (SPM) 4, a voice coil motor (VCM) 8, and a CPU, memory, HDD controller for controlling the head via the board unit 10, A printed circuit board (not shown) on which other circuits are mounted is mounted by screwing or the like.
[0041]
The voice coil motor (VCM) 8 includes a voice coil 17 fixed to the support frame 16 of the head actuator 6, a pair of yokes 18 fixed on the case 2 so as to sandwich the voice coil 17, and one yoke 18 And a fixed magnet 19.
[0042]
A temperature sensor (not shown) for detecting the temperature in the hard disk drive 1 is disposed in the case.
[0043]
FIG. 2 is a block diagram showing the configuration of the control system of the hard disk drive 1.
[0044]
In the figure, a preamplifier circuit 21 has a read amplifier that amplifies a read signal read by a head 29 and a write amplifier that converts write data into a write current. The read / write (W / R) signal processing circuit 22 performs various signal processing such as A / D conversion processing, write data encoding processing, and read data decoding processing. A hard disk controller (HDC) 23 processes an interface between the hard disk drive 1 and a host system (personal computer or digital device), and performs read / write data transfer control, for example.
[0045]
The motor driver 24 includes a VCM driver 24 A for driving the voice coil motor (VCM) 8 and an SPM driver 24 B for driving the spindle motor (SPM) 4.
[0046]
The CPU 25 is a main control device of the hard disk drive 1, and is an element for performing head unload speed control particularly in this embodiment. The CPU 25 monitors the counter electromotive force generated by the VCM driver 24A, calculates the rotation speed (speed) of the voice coil motor (VCM) 8 as the head unload speed, and is set as the head unload speed. The current supplied to the voice coil motor (VCM) 8 is controlled so that the actual head unload speed approaches the target speed.
[0047]
The memory 26 includes a RAM and a flash EEPROM, and stores various parameters such as a control program for the CPU 25 and a default value of a target speed for head unloading.
[0048]
The temperature sensor 28 detects the temperature in the hard disk drive 1 and transmits it to the CPU 25.
[0049]
The CPU 25 optimizes the target speed at the head unloading based on the temperature information notified from the temperature sensor 28, and controls the head unloading speed control, that is, the voice based on the target speed optimized by the environmental temperature. The speed control of the coil motor (VCM) 8 is performed.
[0050]
That is, the CPU 25 obtains data of the back electromotive force (voltage) generated by the voice coil motor (VCM) 8 through the A / D conversion 27 and calculates the actual head unload speed. Then, the actual head unload speed is compared with the target speed optimized by the environmental temperature, and the head unload speed is controlled based on the comparison result.
[0051]
Next, the head unload speed control operation in the hard disk drive 1 will be described.
[0052]
For example, the CPU 25 captures the output of the temperature sensor 28 before starting head unloading. Of course, in this case, not only the temperature immediately before the start of head unloading but also a value obtained by calculating an average temperature for a certain past time, for example, may be used.
[0053]
Based on the acquired temperature information, the CPU 25 sets the target speed for head unloading to an optimum speed corresponding to the environmental temperature.
[0054]
Specific methods for setting the optimum target temperature include the following.
[0055]
(1) Change the target speed setting when the ambient temperature exceeds or falls below a certain reference temperature (range). For example, when 10 to 50 ° C. is set as the reference temperature range, when the environmental temperature exceeds 50 ° C., or when the environmental temperature falls below 10 ° C., an optimum target speed determined in advance for each is set, This optimum target speed is applied to the head / unload speed control.
[0056]
(2) The difference between the environmental temperature and the reference temperature range is obtained in units of a certain temperature range, and an optimum target speed is set according to the obtained temperature difference and applied to the head / unload speed control. For example, when 30 to 40 ° C. is set as the reference temperature range, the optimum target speed is changed depending on whether the environmental temperature is in the range of 20 ° C. or 10 ° C.
[0057]
(3) Set the target speed corresponding to the environmental temperature from the environmental temperature-unload speed relational expression. An example of the environmental temperature-unload speed relational expression is, for example, vt = k × T + va. Here, vt is a target speed, T is an environmental temperature, and k and va are constants.
[0058]
When the optimum target temperature corresponding to the environmental temperature is set by the above method, the back electromotive force (voltage) data generated by the voice coil motor (VCM) 8 is acquired through the A / D converter 27, and the CPU 25 Calculate the actual head unload speed from the data.
[0059]
Subsequently, the actual head unload speed is compared with the optimum target speed. As a result of this comparison, when the actual unload speed is slower than the optimum target speed, the current flowing to the voice coil motor (VCM) 8 is increased so as to increase the head unload speed, and the actual head unload speed is increased. Is faster than the optimum target speed, the current flowing through the voice coil motor (VCM) 8 is reduced so as to lower the unload speed. The procedure from the acquisition of the environmental temperature data from the temperature sensor 28 to the control of the current flowing through the voice coil motor (VCM) 8 is repeated, for example, at regular time intervals. An example of the above head / unload speed control is shown in FIG.
[0060]
In this way, by optimizing the target speed of the head unloading with respect to the environmental temperature, it becomes possible to mitigate the influence of the environmental temperature on the actual head unloading speed. Head unloading errors can be prevented, and the probability of accidents such as head damage due to collision between the head and the stopper at high temperatures can be reduced.
[0061]
The present invention is not limited to any of the above-described embodiments, and can be implemented with appropriate modifications within the scope of the technical idea of the present invention.
[0062]
In the above embodiment, the present invention is applied to a hard disk drive. However, the present invention can also be applied to a disk apparatus using a disk-shaped storage medium other than a hard disk.
[0063]
【The invention's effect】
As described above, according to the present invention, a stable head unload operation is realized against a large change in environmental temperature, and a highly reliable disk device can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a hard disk drive as an embodiment to which a disk device of the present invention is applied.
2 is a block diagram showing a configuration of a control system for the hard disk drive of FIG. 1; FIG.
FIG. 3 is a diagram for explaining control of head unload speed in the hard disk drive of FIG. 1;
FIG. 4 is a diagram showing a positional relationship among a head, a medium, and a lamp at the time of control / unloading from the side.
FIG. 5 is a diagram showing a change in current passed through the voice coil motor during control / unloading.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Hard disk drive, 3 ... Disk, 6 ... Head actuator, 8 ... Voice coil motor (VCM), 9 ... Lamp, 25 ... CPU, 26 .... Memory, 28 ... Temperature sensor, 29 ... Head

Claims (3)

A head portion equipped with an element for reading a signal from a disk-shaped storage medium;
A head actuator that supports the head portion at one end and moves the head portion relative to the storage medium;
A motor for driving the head actuator;
A lamp for localizing the head portion moved to the outer peripheral portion of the storage medium by the head actuator at a predetermined retracted position separated from the storage medium;
A sensor for detecting the temperature;
A first speed corresponding to a predetermined temperature range, a second speed corresponding to a temperature lower than the predetermined temperature range and higher than the first speed, and a temperature higher than the predetermined temperature range. And a memory for storing a third speed smaller than the first speed;
Means for setting a goal speed at which based on the stored contents of the memory has been temperature and detected, moves the head portion to the predetermined retracted position by said sensor,
A control Gosuru means the motor to move the head portion in the set is the target speed to the predetermined retracted position,
A disk device comprising: The system Gosuru hand stage monitors the moving speed of the head portion, obtains a moving speed of said head portion is a result of this monitoring, the difference between the set goals speed according to the temperature, the difference The disk apparatus according to claim 1, wherein a current supplied to the motor is controlled based on the motor. A head portion on which an element for reading a signal from a disk-shaped storage medium is mounted, a head actuator that supports the head portion at one end and moves relative to the storage medium, a motor that drives the head actuator, and the head actuator A head unload control method for a disk device, comprising: a ramp that localizes the head portion moved to the outer peripheral portion of the storage medium by a predetermined retracted position separated from the storage medium;
Detecting the temperature with a sensor;
A first speed corresponding to a predetermined temperature range, a second speed corresponding to a temperature lower than the predetermined temperature range and higher than the first speed, and a temperature higher than the predetermined temperature range. and goal speed when the storage contents of the first speed is less than a third memory for storing the speed, the, and on the basis of the detected temperature, to move the head portion to the predetermined retracted position and the step to set the,
A step that controls the motor so as to move the head portion in the set target speed to the predetermined retracted position,
Head unload control method for a disk device comprising the provided child a.

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