JP2001307451A - Head speed control method, head position detecting method, and disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly control the speed of a head and to detect the position of the head even when the head is at a position where information on a disk can not be read, and to reduce a mechanical shock sound in lamp loading. SOLUTION: A head speed control method for a disk device equipped with an arm having a head atop has a step for controlling the switching of the head speed to plural previously set target speeds in at least one of lamp unloading operation for retracting the head into a parking area not only the recording surface of the disk and lamp loading operation for putting the head, retracted into the parking area, back onto the recording surface of the disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head speed control method, a head position detection method and a disk drive, and more particularly to a head speed control method and a head position detection method suitable for a disk drive having a ramp load / unload mechanism. Also, the present invention relates to a disk device employing such a head speed control method or head position detection method.

[0002]

2. Description of the Related Art In a magnetic disk drive, a head writes and reads signals to and from a magnetic disk.
In the case of a hard disk, a minute gap is provided between the head and the disk. However, when the magnetic disk device is mounted on a portable device such as a notebook personal computer, for example, in order to avoid unnecessary contact between the head and the disk due to external impact or the like, except when the device is operating. The head is retracted to a parking area other than the recording surface of the disk. This means that if the head collides with the disk, both the head and the disk may be damaged.

[0003] Even when the apparatus is not used for a long time, the head is prevented from sticking on the recording surface of the disk due to a lubricant or the like applied to the surface of the disk. Evacuate in the parking area.

The ramp loading / unloading mechanism guides the arm supporting the head along the ramp member at the time of ramp loading for retracting the head to the parking area and at the time of ramp unloading for returning the head from the parking area onto the disk. It is provided for. At the time of ramp unloading, the head is separated from the disk, so that it is not possible to detect the position of the head or to detect and control the speed of the head based on the position information read from the disk. Although the head speed while the arm is guided by the ramp member can be predicted to some extent, accurate head speed prediction is required due to wear of the ramp member, aging, and variations in characteristics of individual devices. Is impossible. Therefore, the head speed can be detected by using the back electromotive voltage of the voice coil motor (VCM) that drives the head. Normally, when the head is retracted to the parking area during ramp loading, when the head reaches the parking area, the base of the arm comes into contact with the stopper and stops.

[0005] In recent years, portable devices such as notebook type personal computers equipped with a magnetic disk device have many opportunities to operate the device using a battery as a power source, so that reduction in power consumption is particularly required. For this reason,
The portable device is provided with a power save mode for gradually reducing power consumption according to the state of the device, and depending on the power save mode, ramp loading is performed. The frequency at which the ramp load is performed tends to increase because further reduction in power consumption is required.

[0006]

In the conventional apparatus, when the head is separated from the recording surface of the disk, such as during a ramp load, the position of the head can be detected even if the head speed is detected. Cannot be controlled properly.

Further, in the conventional device, the base of the arm comes into contact with the stopper and stops when the ramp load is performed. Therefore, a mechanical impact sound is generated when the base of the arm comes into contact with the stopper. There is a problem that the impact sound is annoying to the user as the frequency of the loudness increases, especially as the frequency of the lamp load increases.

Accordingly, the present invention provides a head speed control method capable of appropriately controlling the head speed even when the head cannot read information on the disk, and a head position detection method capable of detecting the head position. It is an object of the present invention to provide a disk drive capable of reducing a mechanical impact sound at the time of a ramp load by adopting a head speed control method and / or a head position detection method.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a head speed control method for a disk drive having an arm having a head at an end thereof, wherein the head is retracted to a parking area other than the recording surface of the disk. Switching the head speed to a plurality of preset target speeds during unloading operation and / or during a ramp loading operation for returning the head retreated to the parking area to the recording surface of the disk. And a head speed control method characterized by including the following.

An object of the present invention is to provide a method for detecting a head position in a disk drive having an arm having a head at the tip, wherein the step of detecting the head speed and the time of the head speed from a reference position at which the head position can be specified are described. And a step of detecting an integrated value.

An object of the present invention is to provide a disk drive provided with a motor for driving an arm having a head at a tip, a first detection circuit for detecting a head speed, and a head from a reference position capable of specifying a head position. The present invention can also be achieved by a disk device including a second detection circuit for detecting a time integration value of the speed.

In the above-mentioned disk device, the reference position may be a position where the head cannot read information on the disk.

Further, in the above disk device, a ramp unload operation for retracting the head to a parking area other than the recording surface of the disk, and returning the head retracted to the parking area to a recording surface of the disk. The apparatus may further include a control unit for controlling the ramp load operation, and the control unit may control the motor to control the head speed variably during at least one of the ramp unload operation and the ramp load operation.

Further, the control unit may be configured to control the motor such that when the head reaches the end point of the parking area during a ramp unload operation, the head is biased toward the end point for a predetermined time. .

An object of the present invention is to provide a disk drive provided with a motor for driving an arm having a head at a tip thereof, wherein the head is retracted to a parking area other than the recording surface of the disk during a ramp unloading operation. At least one of a ramp load operation for returning the head retreated to the parking area on the recording surface of the disk, and a control unit for switching and controlling the head speed to a plurality of target speeds set in advance. It can also be achieved by a disk device.

In the above disk device, the control unit may be configured to control the head speed to a predetermined target speed when the head reaches a predetermined position.

The control section may control the head speed to a predetermined target speed when a predetermined time is reached.

Therefore, according to the present invention, even if the head is at a position where the information on the disk cannot be read,
A head speed control method capable of appropriately controlling the head speed,
A head position detecting method capable of detecting the position of the head, and a disk device capable of reducing a mechanical impact sound at the time of ramp loading by employing such a head speed controlling method and / or a head position detecting method can be realized.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a head speed control method, a head position detection method and a disk drive according to the present invention will be described below with reference to the drawings.

[0020]

FIG. 1 is a diagram showing a basic configuration of an embodiment of a disk drive according to the present invention. In this embodiment of the disk device, the present invention is applied to a magnetic disk device (hard disk drive: HDD) having a hard disk. In this embodiment of the disk drive, one embodiment of the head speed control method according to the present invention and one embodiment of the head position detecting method according to the present invention are employed. In the same figure, (b) is a plan view showing the disk device with the upper part removed, and (a) is a cross-sectional view along (b) a middle line AA.

As shown in FIG. 1, the disk drive is generally provided at a housing 1, a plurality of (two in this embodiment) disks 3 fixed to a hub 2, a plurality of arms 4, and a tip of each arm 4. Head 5, ramp member 6, and stopper 7
Consists of It is needless to say that the basic configuration of the disk device is not limited to the basic configuration shown in FIG. The point is that the disk device only needs to have a ramp load / unload mechanism.

FIG. 2 is a block diagram showing the configuration of the control system of this embodiment of the disk drive. In the figure, a magnetic disk drive (HDD) generally includes a printed circuit assembly (PC).
A) 11 and a disk enclosure (DE) 12. The PCA 11 includes a hard disk controller (HDC) 21, a flash ROM 22, a bus 23,
AM24, MPU25, read channel (RDC) 26
And a servo combination driver (SVC) 27. On the other hand, the DE 12 includes a disk 3, a head 5, a head IC 31, a voice coil motor (VCM) 32, a spindle motor (SPM) 33, and a distortion sensor. The configuration of the HDD shown in FIG. 1 is basically known except for the distortion sensor 34.

In the DE 12, the head IC 31
The head 5 performs predetermined processing on the signal read from the disk 3 and then supplies the signal to the RDC 26 in the PCA 11, and supplies a write signal supplied from the MPU 25 in the PCA 11 to the head 5 to write the signal on the disk 3. The VCM 32 drives the arm 4 based on a control signal supplied from the SVC 27 in the PCA 11. SPM3
3 rotates the disk 3 based on a control signal supplied from the SVC 27 in the PCA 11.

In the PCA 11, the HDC 21 supplies a write and read operation instruction to the MPU 25 based on an instruction from a host system (not shown). MP
The U25 controls the operation with the control system including the SVC 27 based on the instruction from the HDC 21 and the read signal supplied via the RDC 26. The write signal is HDC2
1 and the head IC 31 in the DE 12 via the MPU 25
And the read signal from the head IC 31 is R
It is supplied to the MPU 25 and HDC 21 via the DC 26. The read signal supplied to the HDC 21 is supplied to a host system. The flash ROM 22 stores the MPU2
5 stores various data used for the operation of R5.
The AM 24 temporarily stores various data used when the MPU 25 and the HDC 21 operate.

The configuration of the control system of the disk drive is not limited to the configuration shown in FIG. 2, and it goes without saying that various known configurations can be adopted. In short, it is only necessary that the control system of the disk device has a function of controlling the ramp load / unload mechanism.

Next, the general operation of this embodiment will be described. FIG. 3 is a sectional view showing the lamp member 6, and FIG.
5 is a flowchart for explaining the schematic operation of the present embodiment.

As shown in FIG. 3, the ramp member 6 comprises a plurality of inclined portions and flat portions, and has a parking area 6-1 for retracting the head 5 from a position on the recording surface of the disk 3 when the ramp is unloaded. . Positions at which the head 3 passes or arrives at the time of ramp loading are indicated by P1 to P7. P1
Is the reference position on the disk 3, and P2 is the first position of the ramp member 6.
, P3 is a limit position at which a signal from the disk 3 can be read, P4 is a start position of the flat portion of the ramp member 6 (end position of the first inclined portion), and P5 is a position of the ramp member 6. End position of the flat portion (start position of the second inclined portion), P6 is the end position of the second inclined portion of the ramp member 6 (start position of the parking area 6-1), and P7 is the end point of the parking area 6-1. Indicates the position.

The processing in FIG. 4 corresponds to the operation of the MPU 25 and SVC 27 in the PCA 11 shown in FIG. In FIG. 4, a step S1 issues a ramp unload command in response to an instruction from a higher-level system.
2, the head 5 is a specific cylinder on the disk 3, that is,
A seek operation for seeking to the reference position P1 is started. A step S3 decides whether or not the seek operation has been completed. If the decision result in the step S3 is YES, a step S4 starts the speed control of the head 5, and a step S5 decides whether or not the signal on the disk 3 can be read by the head 5. If the decision result in the step S5 is YES, a known speed control based on a signal read from the disk 3 by the head 5 is performed. On the other hand, if the head 5 moves to the position P3 side beyond the position P2 and the determination result in the step S5 is NO, the process proceeds to the step S6.
Proceed to.

Next, known speed control based on a signal read from the disk 3 by the head 5 will be described with reference to FIG. FIG. 5 is a diagram for explaining the embedded servo method.

As shown in the upper part of FIG. 5, the disk 3 is divided into a plurality of sectors. Servo fields are provided between sectors, and data fields are provided between adjacent servo fields. Each servo field has
Preamble, location information and PAD information are included. The position information includes a gray code indicating a cylinder number and a sector number on the disk 3 and burst information used to indicate a shift in a track and maintain an on-track state. The PAD information indicates the end of the servo field. A read signal including position information in the servo field is output from the RDC 26 shown in FIG.
, The MPU 25 can control the speed of the head 5 based on the position information.

For convenience of explanation, the head speed is determined by the position P
It is assumed to be constant from 1 to just before the position P5,
As will be described later, the head speed can be arbitrarily controlled during the ramp unload operation and the ramp load operation.

Step S6 calculates the speed of the head 5,
The head position is detected by integrating the head speed over time. Specifically, the back electromotive voltage of the VCM 32 is detected by the SVC 27, the head speed is obtained by the MPU 25, and M
The PU 25 detects the head position by time-integrating the head speed with reference to the reference position P1.

FIG. 6 is a block diagram showing a configuration of a power amplifier integrated circuit for detecting a back electromotive voltage of VCM 32. The power amplifier integrated circuit 270 is provided in the SVC 27, and is connected as shown in FIG.
1. Compensator 272, driver 273, sense amplifier 27
4, the differential amplifiers 275 to 277, and the resistors RM 'and RS'. The sense resistor RS is connected to the power amplifier integrated circuit 27.
0 may be provided. LM and RM are VC
3 shows the inductance and resistance of M32. Subtractor 271
Is supplied from the MPU 25 with an instruction value indicating the rotation speed of the VCM 32. Also, from the differential amplifier 277,
A detected back electromotive voltage of the VCM 32, that is, a speed signal indicating the head speed is output, subjected to well-known analog / digital conversion in the SVC 27, and then supplied to the MPU 25 as a digital speed signal. Therefore, MPU25
Can detect the head position by time-integrating the head speed obtained from the speed signal with reference to the reference position P1.

Returning to the description of FIG. 4, step S7 determines whether the head position has reached a preset target position. The target position is a position where the head speed starts decreasing. In the present embodiment, the target position is set to the position P5. Therefore, the determination result of step S7 is NO until the head position is from the position P3 to immediately before the position P5. When the head position reaches the position P5, step S
The determination result in 7 is YES, and a step S8 reduces the head speed to a preset target speed.

A step S9 decides whether or not the head position has reached the end point P7 of the parking area 6-1. In this embodiment, the head position is changed from the position P5 to the position P7.
Until immediately before, the determination result of step S9 is NO.
When the head position reaches the position P7, the determination result in the step S9 becomes YES, and the step S10 controls the VCM 32 so as to bias the head 5 in the direction of the end point P7, that is, in the outer circumferential direction of the disk 3. Specifically, VCM
32 is appropriately controlled. Step S11
Determines whether a predetermined time has elapsed since the head 5 was urged toward the end point position P7, and the determination result is YES
, The process ends.

When the head position reaches the end point position P7,
In FIG. 1, the position of the base of the arm 4 is regulated by contacting the stopper 7. When the head position approaches the end point position P7, the head speed decreases, so that the mechanical impact sound when the base of the arm 4 comes into contact with the stopper 7 is so small that it can be ignored. Further, by urging the head 5 in the direction of the end point position P7 for a certain period of time, the head 5 reliably reaches the end point position P7 and is regulated to the end point position P7,
The base of the arm 4 does not come into contact with the stopper 7 many times to generate a mechanical impact sound. Therefore, at the time of lamp unloading, there is no generation of a mechanical impact sound that is unpleasant to the user.

FIG. 7 is a diagram showing the relationship between time and head position at the time of ramp unloading in this embodiment. In the figure, the vertical axis indicates the moving distance of the head 5, the horizontal axis indicates time, and the shaded portion indicates the integrated value of the head speed.

FIG. 8 is a diagram showing an embodiment of speed control at the time of ramp unloading. In the figure, the vertical axis shows the speed, and the horizontal axis shows the head position. In the present embodiment, the head speed decreases to a certain head speed after passing the target position.

FIG. 9 is a diagram showing another embodiment of the speed control at the time of ramp unloading. In the figure, the vertical axis shows the speed, and the horizontal axis shows the head position. In this embodiment, when the head speed passes the target position, the head speed gradually decreases to a preset head speed. The reduction of the head speed may be performed stepwise or continuously.

FIG. 10 is a functional block diagram showing a head speed control part of the ramp load / unload control system.
The ramp load / unload control system shown in the figure is realized by the MPU 25 and the SVC 27 shown in FIG.

In FIG. 10, the ramp load / unload control system includes subtractors 41 and 42, multipliers 43 and 46, integrators 44, adders 45 and 47, a digital / analog converter (DAC) 48, and a power amplifier. 49 and VCM32
Consists of The subtracter 41 subtracts, for example, an offset correction value at a speed of 0 m / s from the back electromotive voltage from the VCM 32. The offset correction value is used to remove the head speed offset detected from the back electromotive voltage. The subtractor 42 subtracts the current speed output by the subtractor 41 from the target speed when controlling the head speed, and outputs a speed error. The speed error is supplied to a multiplier 43 and an adder 45. The multiplier 43 multiplies the integral gain I, and the integrator 44
Performs time integration (1 / s) on the output of the multiplier 43 and supplies the speed integration error to the adder 45. The multiplier 46 includes the adder 4
5 is multiplied by the proportional gain P, and the speed PI error is supplied to the adder 47. The external force correction current is supplied to the adder 47. The output of the adder 47 is supplied to the VCM 32 via the DAC 48 and the power amplifier 49, and is controlled so that the head speed becomes the target speed. For convenience of explanation, FIG. 10 shows that the back electromotive voltage is output from the VCM 32, but actually, as shown in FIG.
It goes without saying that the signal is output from the power amplifier integrated circuit 270 including the power amplifier 49.

At the time of ramp loading for returning the head 5 to a position on the recording surface of the disk 3, basically, the operation reverse to that at the time of ramp unloading is performed. At the time of ramp loading, it is necessary to control the head speed so that the head 5 does not collide with the recording surface of the disk 3. Therefore, the head speed is controlled in the same manner as when the lamp is unloaded.
When the head 3 passes through the position 3 shown in FIG. 5, the head speed is reduced, so that the collision of the head 5 with the disk 3 can be reliably prevented.

Therefore, according to the present embodiment, by appropriately controlling the head speed at the time of lamp unloading, it is possible to prevent the generation of mechanical impact noise at the time of lamp unloading, and
By properly controlling the head speed during ramp loading,
The head 5 can be prevented from colliding with the disk 3 at the time of ramp loading, and the ramp unloading operation and the ramp loading operation can be performed at high speed.

FIG. 11 is a functional block diagram showing a head position detecting portion of the control system. The control system shown in FIG.
Are realized by the MPU 25 and the SVC 27 shown in FIG.

In FIG. 11, the control system includes an integrator 51,
It comprises a speed integration result storage 52, a subtractor 53, and a distance reaching determination unit 54. The integrator 51 integrates the current speed of the head 5 over time (1 / s), and the speed integration result storage unit 52 stores the speed integration value as the speed integration result and supplies it to the subtractor 53. The speed integral value corresponds to the moving distance of the head 5. The subtractor 53 subtracts the stored moving distance from the reference distance from the reference position to which the head 5 should move to reach the target position. The distance reaching determination unit 54 determines whether or not the moving distance of the head 5 has reached the reference distance based on the result of the subtraction from the subtractor 53, and outputs a reaching signal when reaching. Thus, a reference position capable of specifying the head position is set, and the time integration of the head speed is performed from this reference position, so that the distance between different head positions to the target position is calculated by the time integration value of the head speed. , Head 5
It is easy to know that the travel distance has reached the reference distance, and
It can be detected reliably.

When the head 5 moves down the ramp member 6 and moves onto the disk 3 during the loading of the ramp, the head position can be accurately recognized. There is no need to supply power, so that power consumption is reduced and the life of the head 5 can be extended.

FIG. 12 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system. The control system shown in FIG. 2 includes the MPU 25 and the SVC 2 shown in FIG.
7 is realized. 12, the same parts as those in FIGS. 10 and 11 are denoted by the same reference numerals, and description thereof will be omitted.

In the control system shown in FIG.
The current speed of the head 5 is obtained from the subtractor 41.
The reaching signal output from the distance reaching determination unit 54 is supplied to the speed integration result storage 52, and the speed integration value stored in the speed integration result storage 52 is reset after the speed control of the head 5 is completed.

FIG. 13 shows whether the head 5 has reached the target position by the functional blocks shown in FIGS. 11 and 12, and obtains the current position of the head 5 from the integrated value of the head speed when the ramp is unloaded. It is a flowchart explaining a process. The processing shown in FIG.
This corresponds to the processing of the PU 25 and the SVC 27.

In FIG. 13, step S21 moves the head 5 to the reference position, and step S22 moves the head 5 to the reference position.
It is determined whether or not has reached the reference position. Step S22
Is YES, the step S23 starts moving the head 5 in the direction of the ramp member 6. Step S
24 clears the speed integral value (P) for position calculation.
In step S25, detection of the head speed is started from the back electromotive voltage of the VCM 32. Step S26 is (P) =
The moving distance (P) of the head is obtained from (P) + (current speed). A step S27 decides whether or not the moving distance (P) of the head is greater than or equal to the target distance, and the process ends if the decision result in the step S27 is YES. On the other hand, if the decision result in the step S27 is NO, the process returns to the step S26.

FIG. 14 is a block diagram showing the function of the head 5 based on the integrated value of the head speed at the time of ramp loading by the functional blocks shown in FIG.
6 is a flowchart for explaining a process for obtaining the current position of the. The processing shown in FIG. 14 is performed by the MPU 25 and the SPU shown in FIG.
This corresponds to the process of VC27. 14, steps that are the same as the steps shown in FIG. 13 are given the same reference numerals, and descriptions thereof will be omitted.

In FIG. 14, step S31 is a step of changing the current for moving the head 5 in the outer direction of the disk 3 to VCM.
32, and a step S32 decides whether or not a predetermined time has elapsed. If the decision result in the step S32 is YES, a step S33 starts the movement of the head 5 in the inner direction of the disk 3, and thereafter, the steps S24 to S2.
7 is performed.

FIG. 15 shows whether the head 5 has reached the target position on the disk 3 by the functional blocks shown in FIG.
It is a flowchart explaining the process which determines using an upper reference | standard position. The processing shown in FIG. 15 is performed by the MPU shown in FIG.
25 and SVC27. In FIG. 15, FIG.
The same steps as those in 3 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 15, a step S41 moves the head 5 to a reference position on the disk 3, that is, a specific cylinder position, and a step S42 reads the cylinder number and the cylinder number in the servo field in the signal read from the disk 3. From the gray code indicating the sector number, it is determined whether or not the head 5 has reached the specific cylinder position. Step S4
If the decision result in 2 is YES, a step S43 starts the movement of the head 5 in the outer direction of the disk 3, and thereafter the steps S24 to S27 are performed.

FIG. 16 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system. The control system shown in FIG. 2 includes the MPU 25 and the SVC 2 shown in FIG.
7 is realized. In FIG. 16, the same portions as those in FIG. 12 are denoted by the same reference numerals, and description thereof will be omitted.

In the control system shown in FIG. 16, a read signal output from the head 5 is supplied to a preamplifier output level judging unit 31- via a preamplifier 31-1 in the head IC 31.
2 is supplied. Preamplifier output level determination unit 31-2
Is also supplied with a reference level, and the preamplifier 31
When the read signal level from −1 is smaller than the reference value level, the permission signal is supplied to the distance calculation start permission unit 56. The current speed from the subtractor 41 is supplied to the distance calculation start permission unit 56, and the current speed is supplied to the integrator 51 only when the permission signal is supplied. Thus, the reference position at the time of lamp unloading is set to a position where the signal from the preamplifier 31-1 cannot be read.

FIG. 17 is a flowchart illustrating a process of determining whether or not the head 5 has reached the target position by using the reference position at which the signal from the preamplifier 31-1 cannot be read by the functional blocks shown in FIG. is there. FIG.
7 is performed by the MPU 25 and the SVC 27 shown in FIG.
Corresponding to the processing of. 17, those steps which are the same as those corresponding steps in FIG. 15 are designated by the same reference numerals, and a description thereof will be omitted.

In FIG. 17, in step S51, the position of the head 5 when the read signal from the preamplifier 31-1 becomes smaller than the reference level is set as a reference position.
The head 5 is moved to the reference position. A step S52 decides whether or not the current signal level read from the disk 3 is equal to or lower than the reference level. If the decision result in the step S52 is YES, a step S43 starts the movement of the head 5 in the outer direction of the disk 3, and thereafter, the steps S24 to S27 are performed.

FIG. 18 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system. The control system shown in FIG. 2 includes the MPU 25 and the SVC 2 shown in FIG.
7 is realized. 18, the same parts as those of FIG. 16 are denoted by the same reference numerals, and the description thereof will be omitted.

In the control system shown in FIG. 18, when the output signal level of preamplifier 31-1 is higher than the reference value and during the ramp load operation, preamplifier output level determination section 31-2 outputs a signal indicating that. Is supplied to the speed integration result storage 52. Upon receiving the above signal from the preamplifier output level determination unit 31-2, the speed integration result storage unit 52 supplies the stored speed integration value to the ramp unload reference distance storage unit 58. As a result, the speed integrated value during the ramp load operation is stored in the ramp unload reference distance storage 58. The stored speed integration value at the time of the ramp load operation is supplied to the subtractor 53 as a reference distance. Therefore, at the time of ramp loading, the parking area 6
-1 is integrated from the end point P7 and the preamplifier 31
By storing the distance from -1 to a position where a read signal can be obtained in the ramp unloading reference distance storage 58, the reference position at the time of lamp unloading is stored in the lamp unloading reference distance storage. The setting is made based on the reference distance stored in 58.

FIG. 19 shows a process of setting a reference position at the time of lamp unloading based on the distance to a position where a read signal can be obtained from the preamplifier 31-1 at the time of lamp loading by the functional blocks shown in FIG. It is a flowchart explaining. The processing shown in FIG.
This corresponds to the processing of the PU 25 and the SVC 27. In FIG.
The same steps as those in FIGS. 13, 14, and 17 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 19, steps 31, S32,
After S24, S33, S25, S26, step S27
Is YES, the step S61 is a step of starting the movement of the head 5 from the end point P7 of the parking area 6-1 at the time of ramp loading and then moving the head 5 to a position where a read signal can be obtained from the preamplifier 31-1. The distance is stored in the ramp unload reference distance storage 58, and the process proceeds to step S51. After steps S52 and S24, step S62 is a ramp unload reference distance storage 58.
Is used as a reference distance. After step S62, the process proceeds to steps S43 and S2.
The process sequentially proceeds to 5, S26, and S27.

FIG. 20 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system. The control system shown in FIG. 2 includes the MPU 25 and the SVC 2 shown in FIG.
7 is realized. 20, the same parts as those of FIGS. 12 and 18 are denoted by the same reference numerals, and description thereof will be omitted.

In the control system shown in FIG. 20, the speed integration result storage 52 stores the stored speed integration value during the ramp load operation, as a ramp unload reference distance storage 58.
To supply. As a result, the speed integrated value during the ramp load operation is stored in the ramp unload reference distance storage 58. The stored speed integration value during ramp load operation is
It is supplied to the subtractor 53 as a reference distance. Therefore, at the time of ramp loading, speed integration from the end point P7 of the parking area 6-1 is performed, and a specific cylinder on the disk 3, that is,
When reaching the position where the specific gray code is read, the distance to the specific cylinder is stored in the ramp unloading reference distance storage unit 58, so that the reference position at the time of lamp unloading is the ramp unloading reference distance. Storage 5
8 is set based on the reference distance stored.

FIG. 21 is a flowchart for explaining the process of setting the reference position at the time of ramp unloading based on the distance to a specific cylinder at the time of ramp loading by the functional blocks shown in FIG. The processing illustrated in FIG. 21 corresponds to the processing of the MPU 25 and the SVC 27 illustrated in FIG. FIG.
In FIG. 1, the same steps as those in FIGS. 13 to 15, 17 and 19 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 21, steps 31, S32,
After S33, S24, S25, S26, step S27
Is YES, the step S61 stores the distance from the start point P7 of the parking area 6-1 at the time of ramp loading to the specific cylinder from the start of the movement of the head 5 to the ramp unloading reference distance storage 58. Then, the process proceeds to step S41. Steps S42, S43, S
After 24, a step S62 calls the distance stored in the ramp unload reference distance storage 58 and uses it as the reference distance. After step S62, the process proceeds sequentially to steps S25, S26, and S27.

FIG. 22 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system. The control system shown in FIG. 2 includes the MPU 25 and the SVC 2 shown in FIG.
7 is realized. In FIG. 22, the same portions as those in FIG. 16 are denoted by the same reference numerals, and description thereof will be omitted.

In the control system shown in FIG. 22, the distortion sensor 61 detects the distortion of the suspension 4-1 of the arm 4 supporting the head 5, and supplies a distortion detection signal to the distortion sensor output level determination section 62.

FIG. 23 is a view showing a position where the strain sensor 61 is mounted. In the figure, (a) is a plan view of the arm 4,
(B) is a side view of the arm 4, and shows a state in which the suspension 4-1 rides on the ramp member 6 for convenience of explanation. The strain sensor 61 is mounted in an area 4-2 of the suspension 4-1 of the arm 4 where the distortion of the suspension 4-1 is largest.

Returning to the description of FIG. 22, the reference value level is also supplied to the distortion sensor output level judging section 62.
When the level of the distortion detection signal from the distortion sensor 61 is larger than the reference value level, the permission signal is sent to the distance calculation start permission unit 56.
To supply. The distance calculation start permission unit 56 includes the subtractor 41
Is supplied to the integrator 51 only when the permission signal is supplied. Accordingly, the reference position at the time of the ramp unloading is set to a position where the suspension 4-1 of the arm 4 rides on the ramp member 6 and the strain 4-1 detected by the strain sensor 61 becomes larger than the reference value.

FIG. 24 is a flow chart for explaining the process of setting the reference position at the time of ramp unloading based on the distortion of the suspension 4-1 by the functional blocks shown in FIG. The processing shown in FIG. 24 is performed by the MPU2 shown in FIG.
5 and the processing of the SVC 27. 24, FIG.
The same steps as those described above are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 24, after step S31, step S71 determines whether or not the distortion detection signal from distortion sensor 61 is larger than the reference value. If the determination result is YES, the process proceeds to steps S24, S25, and S25. S26, S2
Continue to step 7.

FIG. 25 is a functional block diagram showing a head speed control portion of the control system. The control system shown in FIG.
Are realized by the MPU 25 and the SVC 27 shown in FIG. 22, the same parts as those of FIG. 10 are denoted by the same reference numerals, and the description thereof will be omitted.

In the control system shown in FIG. 25, the target speed selector 71 controls the head 5 during the ramp load / unload.
To set multiple target speeds. In this embodiment, two target speeds are set to be switched for convenience of explanation. Each target speed is supplied to the subtractor 42 as a target speed. The plurality of target speeds set in the target speed selector 71 are, for example,
May be supplied to the MPU 25 and the SVC 27 via the. Thus, a plurality of target speeds can be switched and set during the ramp load / unload operation, and the head speed can be controlled to a speed suitable for the head position. That is, the head speed can be variably controlled during the ramp load / unload operation.

FIG. 26 is a flowchart for explaining processing for variably controlling the head speed during the ramp load / unload operation by the functional blocks shown in FIG. In FIG. 26, a step S71 detects a head speed from a back electromotive voltage of the VCM 32, and a step S72 obtains a speed error by subtracting the detected speed from the target speed. In step S73, the speed error is multiplied by a constant gain to
2 is obtained. A step S74 decides whether or not a target speed change request signal has been supplied from the target speed selector 71. If the decision result in the step S74 is NO, the process returns to the step S71.

On the other hand, if the decision result in the step S74 is YES.
In step S75, the target speed is changed to the changed target speed. A step S76 detects a head speed from the back electromotive voltage of the VCM 32, and a step S77 subtracts the detected speed from the target speed to obtain a speed error. In step S78, the speed error is multiplied by a constant gain, and VC
An instruction current value to M32 is obtained. A step S79 decides whether or not the speed control end request signal has been supplied, and if the decision result in the step S79 is NO, the process returns to the step S76. The process ends if the decision result in the step 79 is YES.

FIG. 27 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system. The control system shown in FIG. 2 includes the MPU 25 and the SVC 2 shown in FIG.
7 is realized. 27, those parts that are the same as those corresponding parts in FIG. 25 are designated by the same reference numerals, and a description thereof will be omitted.

In the control system shown in FIG. 27, a target speed selector 71 switches and sets a plurality of target speeds of the head 5 at the time of ramp loading / unloading in response to a reaching signal from the distance reaching determination unit 54. In this embodiment, the target speed selector 71 outputs the target speed before the arrival signal is input, and outputs the target speed after the arrival signal is input.

FIG. 28 is a flowchart for explaining processing for variably controlling the head speed during the ramp load / unload operation by the functional blocks shown in FIG. 28, those steps which are the same as those corresponding steps in FIGS. 13 and 26 are designated by the same reference numerals, and a description thereof will be omitted. In FIG. 28, after steps S24, S25, S72, S73, and S26 are sequentially performed, a step S80 determines whether or not the moving distance (P) of the head is equal to or longer than the distance at which the speed is changed. Is NO, the process returns to step S25. On the other hand, if the decision result in the step S80 is YES, the process proceeds to a step S75, and the steps S75 to S79 are sequentially performed. Thus, when the head 5 reaches the preset speed, the head speed can be controlled to the preset target speed.

FIG. 29 is a flow chart for explaining processing for variably controlling the head speed during the ramp load / unload operation by the functional blocks shown in FIG. 29, those steps which are the same as those corresponding steps in FIG. 28 are designated by the same reference numerals, and a description thereof will be omitted. In FIG. 29, step 81 is
It is determined whether or not the moving distance (P) of the head is equal to or longer than the remaining distance of the ramp member 6 to the parking area 6-1. If the determination result is NO, the process returns to step S25. On the other hand, if the decision result in the step S81 is YES, the process proceeds to a step S75, wherein the steps S75 to S75 are performed.
79 are sequentially performed. Thus, when the head 5 approaches the parking area 6-1, the head speed can be controlled to a preset target speed, and the head speed when the base of the arm 4 abuts on the stopper 7 is appropriately reduced. As a result, it is possible to suppress the generation of mechanical impact noise.

FIG. 30 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system. The control system shown in FIG. 2 includes the MPU 25 and the SVC 2 shown in FIG.
7 is realized. 30, those parts that are the same as those corresponding parts in FIG. 25 are designated by the same reference numerals, and a description thereof will be omitted.

In the control system shown in FIG. 30, a target speed selector 71 switches and sets a plurality of target speeds of the head 5 at the time of ramp loading / unloading in response to a reaching signal from the distance reaching determination unit 54. In this embodiment, the time counter 72 starts counting up the time in response to the speed control start signal, and is reset in response to the speed control end request signal. The count value of the time counter 72 is supplied to a comparator 73 and compared with a preset target time. The comparator 73 supplies a target speed change request signal according to the comparison result to the target speed selector 71. This allows
The target speed selector 71 outputs the target speed until the preset target time is reached, and outputs the target speed after the target time is reached.

FIG. 31 is a flowchart for explaining processing for variably controlling the head speed during the ramp load / unload operation by the functional blocks shown in FIG. 31, the same steps as those of FIG. 26 are denoted by the same reference numerals, and a description thereof will be omitted. In FIG. 31, step S85
Clears the time counter 72, and step S86
The time counter 72 starts counting up. After steps S25, S72, and S73 are sequentially performed, step S87 determines whether or not the count value of the time counter 72 is equal to or longer than the target time. If the determination result is NO, the process returns to step S86. . On the other hand, if the decision result in the step S87 is YES, the steps S75 to S79 are sequentially performed.

FIG. 32 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system. The control system shown in FIG. 2 includes the MPU 25 and the SVC 2 shown in FIG.
7 is realized. 32, the same parts as those of FIG. 12 are denoted by the same reference numerals, and the description thereof will be omitted.

In the control system shown in FIG.
A current selector 81 is provided between and the multiplier 46. The current selector 81 is supplied with an instruction current value and a reaching signal from the distance reaching determination unit 54. Before the arrival signal is input, the current selector 81
By supplying the output of 5 to the multiplier 46, the same speed control as described above is performed. After the arrival signal is input, the current selector 81 supplies the instruction current value to the multiplier 46. That is, the speed of the head 5 at the time of ramp loading / unloading can be controlled to a target speed corresponding to a command current value set in advance according to the head position on the ramp member 6. Therefore, for example, when the head 5 approaches the parking area 6-1 at the time of ramp unloading, the brake can be applied by controlling the head speed to a target speed corresponding to a preset instruction current value. It is possible to appropriately reduce the head speed at the time when the base comes into contact with the stopper 7, thereby suppressing the generation of mechanical impact noise.

FIG. 33 is a flowchart for explaining processing for variably controlling the head speed during the ramp load / unload operation by the functional blocks shown in FIG. 33, those steps which are the same as those corresponding steps in FIG. 28 are designated by the same reference numerals, and a description thereof will be omitted. In FIG. 33, if the decision result in the step S81 is YES, a step S91 supplies the VCM 32 with a current for moving the head 5 at a constant speed in the outer direction of the disk 3, that is, an instruction current value. Also, a step S92 decides whether or not a certain time has elapsed,
When the result of the determination is YES, the process ends.

FIG. 34 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system. The control system shown in FIG. 2 includes the MPU 25 and the SVC 2 shown in FIG.
7 is realized. 34, the same parts as those of FIG. 32 are denoted by the same reference numerals, and the description thereof will be omitted.

In the control system shown in FIG. 34, the speed judging section 85 determines that the current speed supplied from the subtractor 41 is 0 m / s.
And outputs a signal. The error amount determination unit 86 outputs a signal when the speed integration error from the integrator 44 is equal to or greater than a certain value. When the collision determination unit 87 is supplied with both the signal from the speed determination unit 85 and the signal from the error amount determination unit 86,
It is determined that the base of the arm 4 has collided with the stopper 7, and the arrival signal indicating that the head 5 has reached the end point P7 of the parking area 6-1 is supplied to the current selector 81. Before the arrival signal is input, the current selector 81
By supplying the output of 5 to the multiplier 46, the same speed control as described above is performed. After the arrival signal is input, the current selector 81 supplies the instruction current value to the multiplier 46. The instruction current value in this case is a current supplied to the VCM 32 so as to move the head 5 in the outer direction of the disk 3 at a constant speed. That is, when the lamp is unloaded, the head 5
After reaching the end point P7 of the parking area 6-1, the command current value for further moving the head 5 in the outer direction is VC
By supplying the head 5 to the M32, the head 5 is urged in the outer direction from the end point P7, and is reliably positioned at the end point P7.

FIG. 35 is a flow chart for explaining processing for variably controlling the head speed during the ramp load / unload operation by the functional blocks shown in FIG. In FIG. 35, a step S101 clears an internal counter of the collision determination unit 87. The internal counter counts the number of times that the speed determination unit 85 continuously detects that the current speed is 0 m / s. In step S102, V
The current speed is detected from the back electromotive voltage of the CM 32. A step S103 decides whether or not the speed judging section 85 has detected that the current speed is 0 m / s based on a detection signal from the speed judging section 85. If the judgment result is NO, the process is terminated. It returns to step S101.

On the other hand, if the decision result in the step S103 is YE
If it is S, a step S104 counts up the internal counter based on the detection signal from the speed determination unit 85. A step S105 decides whether or not the count value of the internal counter is equal to or larger than a preset number of times of collision determination with respect to the end point P7 of the parking area 6-1. It returns to S102.
If the decision result in the step S105 is YES, a step S106 supplies an instruction current for moving the head 5 in the outer direction of the disk 3 at a constant speed to the VCM 32. A step S107 decides whether or not a predetermined time has elapsed, and if the decision result in the step S107 is NO, the process proceeds to a step S107.
Return to 106. On the other hand, if the determination result of step S107 is Y
If it is ES, the process ends.

Next, the processing for obtaining the moving distance of the head 5 will be described. FIG. 36 is a flowchart for explaining the processing for obtaining the moving distance of the head 5. The processing shown in FIG. 36 is optimal for obtaining the moving distance of the head 5 in step S26 in FIG. 13, for example.

In FIG. 36, a step S111 starts, for example, the speed detection operation of the control system shown in FIG. A step S112 detects a back electromotive voltage of the VCM 32.
A step S113 converts the back electromotive voltage into the current speed of the head 5. In step S114, integration of the current speed of the head 5 is started. A step S115 obtains the moving distance of the head 5 from the speed integral value, and the process ends. As a result, the current speed of the head 5 is obtained from the back electromotive voltage of the VCM 32, and the moving distance of the head 5 can be obtained by integrating the current speed.

FIG. 37 is a functional block diagram showing a head moving distance calibration portion of the control system. The head moving distance calibration portion performs the calibration of the moving distance of the head 5 based on the position information written on the disk 3. The control system shown in the figure is realized by the MPU 25 and the SVC 27 shown in FIG. In FIG. 37, the same portions as those in FIG. 32 are denoted by the same reference numerals, and description thereof will be omitted.

In the control system shown in FIG.
Subtracts the back electromotive voltage from the VCM 32 from the offset correction value at the speed of 0 m / s, and supplies the current speed of the head 5 to the distance calculation start permitting unit 92. Distance calculation start permission unit 9
2 permits the start of distance calculation and supplies the current speed to the integrator 93 based on the calibration seek start instruction. Integrator 9
The speed integral value from 3 is supplied to the integral correction calculator 94 to which the correction coefficient stored in the correction coefficient storage unit 97 is supplied. The integration correction calculator 94 multiplies the speed integration value (moving distance of the head 5) by a correction coefficient, obtains the true moving distance of the head 5, and supplies it to the speed integration result storage 95.

The speed integration result storage 95 is supplied with a calibration seek completion instruction and a reset signal from the correction coefficient storage 97. The correction coefficient storage unit 97 resets the speed integration result storage unit 95 by the reset signal after the calibration is completed. The true moving distance stored in the speed integration result storage 95 is calculated by the arithmetic unit 9 in response to the calibration seek completion instruction.
6. The arithmetic unit 96 calculates A / B from the moving distance A obtained from the difference between the track numbers at the start of the calibration seek and the completion of the calibration seek, and the true distance B stored in the speed integration result storage 95. Calculate the correction coefficient. The calculated correction coefficient is stored in the correction coefficient storage unit 97. Needless to say, a cylinder number may be used instead of a track number.

FIG. 38 is a flowchart for explaining a process of calibrating the moving distance of the head 5 based on the position information written on the disk 3 by the functional blocks shown in FIG.

In FIG. 38, step S121 is
The CM 32 is activated and the head 5 is sought to the reference position on the disk 3.
Supply to CM32. A step S123 clears the velocity integral value (P) for calculating the head position, and a step S12.
No. 4 starts detecting the head speed from the back electromotive voltage of the VCM 32. A step S125 obtains the moving distance (P) of the head 5 from (P) = (P) + (current speed), and a step S126 determines whether or not the head 5 has reached the target position. If the decision result in the step S126 is NO,
The process returns to step S125. On the other hand, step S12
If the decision result in the step 6 is YES, a step S127 decides
The track position difference information A is obtained by subtracting the track position before calibration from the current track position. In step S128, the true moving distance information B obtained from the speed integral value
Based on the track position difference information A, a correction coefficient A / B is calculated, and a step S129 stores the correction coefficient.

In step S130, the reference position is confirmed, and in step S131, it is determined whether the head 5 has reached the reference position. If the determination result of step S131 is Y
When it becomes ES, step S132 is a speed integral value (P)
Clear In step S133, detection of the head speed is started from the back electromotive voltage of the VCM 32. Step S
In step S134, the stored correction coefficient is called, and
135 calculates the true moving distance of the head 5 by multiplying the speed integral value (P) by the correction coefficient. Step S136 is:
The moving distance (P) of the head 5 is obtained from (P) = (P) + (current speed), and a step S137 determines whether or not the moving distance (P) is equal to or longer than the target distance. Step S13
If the decision result in the step 7 is NO, the process proceeds to a step S136.
Returning to YES, the process ends.

In the above embodiment, the head speed control and head position detection during ramp loading / unloading have been described. However, the present invention is not limited to this. For example, a signal on the disk 3 cannot be read for some reason. In this case, head speed control and head position detection can be performed. Therefore, even if the head 5 is located on the disk 3 but the head position cannot be detected based on the read signal due to a failure, the head speed and the head position can be recognized by the present invention. Therefore, in such a case, the lamp 5 can be immediately unloaded to protect the head 5 and the disk 3.

The present invention has been described with reference to the embodiments.
The present invention is not limited to the above embodiments, and it goes without saying that various modifications and improvements can be made within the scope of the present invention.

[0101]

According to the present invention, a head speed control method capable of appropriately controlling the head speed even when the head is at a position where information on the disk cannot be read, and a head capable of detecting the head position A position detecting method, and a disk device capable of reducing a mechanical impact sound at the time of ramp loading by employing such a head speed controlling method and / or a head position detecting method can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of an embodiment of a disk device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a control system of the embodiment of the disk device.

FIG. 3 is a sectional view showing a lamp member.

FIG. 4 is a flowchart illustrating a schematic operation of the embodiment of the disk device.

FIG. 5 is a diagram for explaining an embedded servo system.

FIG. 6 is a block diagram showing a configuration of a power amplifier integrated circuit for detecting a back electromotive voltage of a VCM.

FIG. 7 is a diagram illustrating a relationship between a time at the time of ramp unloading and a head position.

FIG. 8 is a diagram showing an embodiment of speed control at the time of ramp unloading.

FIG. 9 is a diagram showing another embodiment of speed control at the time of ramp unloading.

FIG. 10 is a functional block diagram showing a ramp load / unload control system.

FIG. 11 is a functional block diagram illustrating a head position detection portion of a control system.

FIG. 12 is a functional block diagram illustrating a head speed control portion and a head position detection portion of the control system.

FIG. 13 is a flowchart illustrating a process of determining whether or not the head has reached a target position and obtaining a current position of the head from an integrated value of the head speed at the time of ramp unloading.

FIG. 14 is a flowchart illustrating a process for obtaining a current position of a head from an integrated value of a head speed at the time of ramp loading.

FIG. 15 is a flowchart illustrating a process of determining whether a head has reached a target position using a reference position on a disk.

FIG. 16 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system.

FIG. 17 is a flowchart illustrating a process of determining whether a head has reached a target position using a reference position at which a signal from a preamplifier cannot be read.

FIG. 18 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system.

FIG. 19 is a flowchart illustrating a process of setting a reference position at the time of lamp unloading based on a distance to a position where a read signal can be obtained from a preamplifier at the time of lamp loading.

FIG. 20 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system.

FIG. 21 is a flowchart illustrating a process of setting a reference position at the time of ramp unloading based on a distance to a specific cylinder at the time of ramp loading.

FIG. 22 is a functional block diagram illustrating a head speed control portion and a head position detection portion of the control system.

FIG. 23 is a view showing a mounting position of a strain sensor.

FIG. 24 is a flowchart illustrating a process of setting a reference position at the time of ramp unloading based on suspension distortion.

FIG. 25 is a functional block diagram showing a head speed control part of the control system.

FIG. 26 is a flowchart illustrating a process of variably controlling a head speed during a ramp load / unload operation.

FIG. 27 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system.

FIG. 28 is a flowchart illustrating a process of variably controlling a head speed during a ramp load / unload operation.

FIG. 29 is a flowchart illustrating a process of variably controlling a head speed during a ramp load / unload operation.

FIG. 30 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system.

FIG. 31 is a flowchart illustrating a process of variably controlling a head speed during a ramp load / unload operation.

FIG. 32 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system.

FIG. 33 is a flowchart illustrating processing for variably controlling the head speed during a ramp load / unload operation.

FIG. 34 is a functional block diagram showing a head speed control portion and a head position detection portion of the control system.

FIG. 35 is a flowchart illustrating a process of variably controlling a head speed during a ramp load / unload operation.

FIG. 36 is a flowchart illustrating a process of obtaining a moving distance of a head.

FIG. 37 is a functional block diagram showing a head moving distance calibration portion of the control system.

FIG. 38 is a flowchart illustrating a process of calibrating a moving distance of a head based on position information written on a disk.

[Explanation of symbols]

 3 disk 5 head 21 HDC 25 MPU 26 RDC 27 SVC 32 VCM 33 SPM

Claims (9)

[Claims] 1. A head speed control method for a disk drive having an arm having a head at a tip thereof, comprising: a ramp unload operation for retracting the head to a parking area other than a recording surface of the disk; At least one of the ramp loading operations for returning the head retreated to the recording surface of the disk to
A head speed control method, comprising the step of controlling to switch the head speed to a plurality of target speeds set in advance. 2. A method for detecting a head position in a disk drive having an arm having a head at a tip, comprising: detecting a head speed; and calculating a time integration value of the head speed from a reference position capable of specifying the head position. Detecting the head position. 3. A disk drive provided with a motor for driving an arm having a head at a tip, a first detection circuit for detecting a head speed, and a time of a head speed from a reference position capable of specifying a head position. A disk device, comprising: a second detection circuit that detects an integrated value. 4. The disk device according to claim 3, wherein the reference position is a position where the head cannot read information on the disk. 5. A ramp unload operation for retracting the head to a parking area other than the recording surface of the disk and a ramp loading operation for returning the head retracted to the parking area to a recording surface of the disk. 4. The control unit further comprising: a control unit configured to control the motor to control the head speed variably in at least one of a ramp unload operation and a ramp load operation. 5. 5. The disk device according to 4. 6. The control unit controls the motor such that when the head reaches an end point of the parking area during a ramp unload operation, the head is biased in the direction of the end point for a predetermined time. 6. The disk device according to claim 5, wherein 7. A disk drive provided with a motor for driving an arm having a head at a tip thereof, wherein the head is retracted to a parking area other than the recording surface of the disk during a ramp unload operation, and At least one of a ramp loading operation for returning the retracted head to the recording surface of the disk,
A disk device, comprising: a control unit configured to switch and control a head speed to a plurality of target speeds set in advance. 8. The disk device according to claim 7, wherein the control unit controls the head speed to a predetermined target speed when the head reaches a predetermined position. 9. The disk device according to claim 7, wherein said control unit controls the head speed to a predetermined target speed when a predetermined time is reached.