JPH0636482A - Device for driving head - Google Patents

Abstract

(57) [Summary] [Purpose] To move the head in a disk device favorably and in a short time with low power consumption. [Structure] First, the head is accelerated by the acceleration current _IDR . When the head speed reaches the preset maximum speed V _MAX , the output of the acceleration current I _DR is stopped and the voice coil of the VCM is short-circuited within the access time. Then, in the VCM, the counter electromotive force is generated in the voice coil by the action of the magnetic field of the magnet, and the head is decelerated. This reduces the power required for deceleration. When the head speed reaches a preset deceleration start speed V _SR , a deceleration current flows in the voice coil in the opposite direction, and the head is decelerated. Then, after waiting for rotation, the access is completed when the head reaches the target position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head drive device in a magnetic disk drive device or the like, and more specifically, it is used in a so-called notebook type personal computer or palm-sized palmtop type personal computer. The present invention relates to a head drive device suitable for a relatively small magnetic disk having a disk size of 2.5 inches, 1.8 inches, or 1.3 inches.

[0002]

2. Description of the Related Art Magnetic disks such as hard disks are
For example, as shown in FIG. 7, concentric tracks T0, ..., T100, ... Having a constant width are divided in the diameter direction, and each track T is a sector sector S1.
The rotation direction is divided by S2, ..., S48. Servo signals SV1, SV2, ..., SV4 for positioning the head and generating a speed signal of the spindle motor are provided on the heads of these sectors S1, S2 ,.
8 is recorded. Each servo signal has one index recognition signal for one rotation of the disk, an absolute address formed by a gray code for each track to perform head positioning in a rough track direction, and two bursts A and B for accurate positioning. Signal, respectively.

Such a disk is assembled in a room with a high degree of cleanliness because it is necessary to reduce the dust that causes a head crash to the maximum extent, and the base and the housing are sealed with a sealing material. To further explain the configuration of the magnetic disk device, a spindle motor for rotationally driving the disk 100 is of an in-hub type with respect to a predetermined base (not shown), and a magnetic circuit is provided inside the disk 100. The configuration is arranged. Heads 102 for writing and reading information to and from the disc are provided on the front and back surfaces of the disc 100, respectively.

Next, the head 102 is supported at one end of a rotary actuator 104. The rotary actuator 104 is configured around a rotary arm 108 rotatably supported by a pivot shaft 106, a head 102 is provided at one end thereof, and the rotary arm 108 is rotationally driven at the other end. Voice coil motor (hereinafter referred to as "VCM") 11 for
A 0 voice coil 112 is provided. VCM11
No. 0 magnet is provided on the base side (not shown), and the spindle motor and the pivot shaft 1 are attached to the base.
The bearing portion 06 is fixedly supported. The base is sealed in a housing (not shown) via a sealing means (not shown).

Further, the base yoke is provided with a connector for electrical connection with the outside. A flexible printed circuit board having a required circuit is provided between the connector and the head 102 or the rotary actuator 104 to form an integrated assembly.

By the way, in such a head drive device, conventionally, the head is moved during read / write as shown in FIG. That is, first, a maximum current is supplied to the voice coil 112 in a direction in which the head 102 is accelerated so that the control time at the time of seek is minimized (see FIG. 7B). The amount of electricity to the voice coil 112 is V
Since it is proportional to the acceleration of the CM 110, the rotary arm 1
08 will be accelerated as shown in FIG.
Then, at the time when the vehicle is accelerated to a predetermined speed, the maximum current in the reverse direction is made to flow through the voice coil 108 by using the deceleration table obtained in advance (see FIG. 7B). Then, the rotary arm 108 is decelerated to the target track position as shown in FIG. After that, the disk 100 is rotated and the rotation is waited until the head 102 reaches the desired sector, and the access to the desired sector is completed.

[0007]

However, such a conventional technique has the following disadvantages. (1) In the ultra-thin magnetic disk drive installed in notebook PCs, palmtop PCs, etc., although the size of the disk is small, the storage capacity per disk remains unchanged or increases. There is. Therefore, it is necessary to increase the recording density on the disc. As a method for this, in addition to making the particles of the magnetic material fine and improving the magnetic characteristics, in the type in which the head flies over the disk, the flying height must be 0.1 μm or less.
The problem here is to shorten the access time,
It is necessary to increase the head speed when seeking, but increasing the speed increases the vibration of the head and causes a head crash.

(2) Further, in order to increase the head speed, the amount of current supplied to the voice coil of the actuator has to be increased, which causes a disadvantage that power consumption increases. The present invention focuses on these points, and an object thereof is to provide a low power consumption head drive device capable of reducing the occurrence of head crash and satisfactorily moving the head in a short time. To do.

[0009]

SUMMARY OF THE INVENTION According to the present invention, in a head drive device for controlling energization of a coil of an actuator to move a head on a disk to be accessed, the head moves from a current position on the disk to a target position. Find the access time required to access up to
In the range of this value, in consideration of the drive characteristics of the actuator, drive condition setting means for setting drive conditions including deceleration due to short circuit of the coil, speed detecting means for detecting the moving speed of the head, and the speed detecting means for detecting the moving speed of the head Further, there is provided drive control means for performing energization of an acceleration current of the coil, short-circuiting and energization of a deceleration current according to the drive condition according to the head moving speed.

[0010]

According to the present invention, the actuator coil is short-circuited after acceleration within the final access time to reach the target position of the disk. Therefore, the counter electromotive force is generated in the coil and the deceleration is performed. Therefore, the power consumption accompanying the movement of the coil is reduced. Further, since the deceleration by the back electromotive force is performed according to the speed of the coil, the vibration of the head is suppressed and the occurrence of head crash is reduced.

[0011]

Embodiments of the head drive device according to the present invention will be described below with reference to the accompanying drawings. The same reference numerals are used for the same components as those of the above-described conventional example or components corresponding to those of the conventional example. <First Embodiment> First, a first embodiment of the present invention will be described. FIG. 1 shows the electrical components of a magnetic disk drive to which this embodiment is applied. In the figure, heads 12 and 14 for accessing the magnetic disk 100 are read / write (R / W) amplifiers 16.
The R / W amplifier 16 is connected to a pulse detector 20 of an R / W controller 18 which controls reading and writing of data. The pulse detector 20 is further connected to the data separator 22,
The data separator 22 is connected to a hard disk controller 24 that controls the exchange of data with the outside.

In the hard disk controller 24, the data separator 22, the memory 26, the gate array 28 for generating various timing pulses, and the like, and the microcomputer 3 for controlling the operation of the whole are provided by an appropriate bus.
0 and the connection terminal 32 are connected. The connection terminal 32 is connected to, for example, a notebook type personal computer main body (not shown).

On the other hand, S for rotating the magnetic disk 100
The PM (spindle motor) 34 has an SPM driver 36
Is connected to the VC for moving the heads 12 and 14.
A VCM driver 40 is connected to M110. The output side of the gate array 28 described above is connected to the SPM driver 36, and the microcomputer 30 and the servo control unit 42 are connected to the VCM driver 40. In addition, the gate array 28 and the servo control unit 42,
The pulse detector 20 is also connected to these, and the motors 34 and 38 and the servo control unit 42 are also connected to the microcomputer 30.

FIG. 2 shows an example of the configuration of the VCM driver 40 described above. In the figure, the input side of the direction signal indicating the energizing direction output from the microcomputer 30 is connected to the inverter AI, the base of the PNP type transistor Q1 and the base of the NPN type transistor Q2. Inverter A
The output side of I is a PNP type transistor Q3 and NPN.
Type transistor Q4.
Note that resistors R1 to R1 are provided at the bases of the transistors Q1 to Q4.
R4 are each connected in series. The emitters of the transistors Q1 and Q2 are connected, and the emitters of the transistors Q2 and Q4 are connected. The collectors of the transistors Q1 and Q2 are connected, and the collectors of the transistors Q3 and Q4 are also connected. The voice coil 112 of the VCM 110 is connected between these collectors.

Appropriate power supply voltage is applied to the emitter side of the transistors Q1 and Q3, and
The emitter side of Q4 is grounded via a transistor Q5 and a resistor R. A current control signal is input from the servo control unit 42 to the base of the transistor Q5. A switch SW for short circuit is connected to the voice coil 112, and a short signal is input to the switch SW from the microcomputer 30.

The VCM driver 40 configured as described above
When the direction signal has a logical value "L", the transistors Q1 and Q4 are turned off.
It is turned on from F to conduct electricity. Then, in the figure, the arrow FA
As shown in, current flows. On the contrary, when the direction signal has a logical value of "H", the transistors Q2 and Q3 are turned from OFF to ON and become conductive. Then, a current flows as indicated by an arrow FB in the figure. That is, one of the pairs of transistors located on the diagonal line becomes conductive according to the logical value of the direction signal, and the direction of the current flowing through the voice coil 112 is reversed.

The current value at this time is limited by the transistor Q5 and the resistor R. That is, the current value is defined by the control of the transistor Q5 by the current control signal output from the servo control unit 42. Further, when a short signal is input from the microcomputer 30, the switch SW is turned from OFF to ON and the voice coil 112 is short-circuited. When the voice coil 112 is short-circuited when the head is moved, a counter electromotive force is generated to act as a generator, and the movement operation is braked. At this time, the microcomputer 30 controls the transistor Q5 to be off.

Next, the microcomputer 30 will be described with reference to FIG. Note that FIG. 3 shows only the functional blocks related to the present embodiment. In the figure, the current and target head position information outputs supplied from the hard disk controller 24 and the servo control unit 42 are input to the drive condition setting unit 30A. The current head position information supplied from the servo control unit 42 is also input to the speed calculation unit 30B. The drive condition set by the drive condition setting unit 30A is stored in the memory unit 30C.
Are stored in the setting condition storage unit 30D. A ROM table 30E is included in the memory unit 30C, and data required for seek control is stored in advance.

The calculation data of the speed calculating section 30B is stored in the setting condition storing section 30D together with the speed determining section 30F.
Is being supplied to. The determination data of the speed determination unit 30F is
The drive instruction unit 30 together with the data stored in the memory unit 30C
It is supplied to G. Then, a control signal is output from the drive instructing unit 30G to the VCM driver 40 and the servo control unit 42.

Of the above units, the drive condition setting unit 30A
Compares the current position of the heads 12 and 14 with the target position, and drives the heads 12 and 14, that is, the acceleration current,
It is for setting the maximum speed and deceleration start speed, and the setting conditions are the setting condition storage unit 3 of the memory unit 30C.
It is designed to be stored in 0D. The ROM table 30E of the memory unit 30C stores data such as a standard time table for performing head seek in the shortest time, a deceleration table that defines deceleration current, and rotation condition parameters of the actuator 104. As the rotation condition parameter, for example, the moment of inertia of the VCM 110,
A back electromotive force constant determined by the magnetic flux generated from the magnet of the VCM 110 during rotation, the shape of the voice coil 112, and the number of turns, tension of a flexible printed circuit board that transmits bearings and signals, wind generated by the spindle motor 34 during rotation, etc. Load is taken into consideration.

Next, the speed calculator 30B is for calculating the speed of the heads 12 and 14 from the position data. The current position data and speed of the heads 12 and 14 are obtained as follows. That is, since the disk 100 is rotating at a constant speed, the servo signal SV
, SV2, ... Are detected by the heads 12, 14. The detected servo signal is read by the R / W controller 18
Is supplied to the servo control unit 42 for A / D conversion, and the converted digital signal is supplied to the microcomputer 30. The drive condition setting unit 30A and the speed calculation unit 30B of the microcomputer 30 recognize the current position by counting the number of sectors from the servo signal based on the track positions of the heads 12 and 14 and the index signal. Also,
The head speed is calculated by differentiating the amount of change.

Next, the speed judgment unit 30F is composed of the speed calculation unit 3
This is to determine whether or not the head speed has reached the maximum speed or the deceleration start speed by comparing the head speed calculated at 0B with the setting condition stored in the memory unit 30C. The drive instructing unit 30G includes a memory unit 30C.
Depending on the stored data of the and the determination result of the speed determination unit 30F,
VCM driver 4 for direction signals and short signals
0 for outputting a current value instruction signal to the servo control unit 42. In the servo control unit 42, the current value control signal is VC based on the current value instruction signal.
It is adapted to be output to the M driver 40.

Next, the overall operation of the present embodiment configured as described above will be described with reference to the time chart of FIG. 4 and the flowchart of FIG. Note that FIG.
Shows a simplified relationship between current and speed, which is not always the case in practice. The operation of the apparatus shown in FIG. 1 is basically the same as that of a general hard disk drive that has been put into practical use, except for the operation of the heads 12 and 14 when seeking. That is, when the disk 100 is accessed from the personal computer through the connection terminal 32, the driver 40 drives the VCM 38 based on instructions from the gate array 28, the microcomputer 30, and the servo control unit 42. Then, the heads 12 and 14 move to access a required address on the disk 100, and the R / W amplifier 16 reads or writes data based on an instruction from the R / W controller 18.

In this case, an external device (not shown)
With command input from (Fig. 5, step SA),
The target track and sector are detected by the drive condition setting unit 30A of the microcomputer 30 (step S
B). On the other hand, the microcomputer 30 is input with the information of the current tracks and sectors of the heads 12 and 14 from the servo control unit 42, which is the drive condition setting unit 30A.
(Step SC). Drive condition setting unit 30
In A, the current positions of the heads 12 and 14 are compared with the target positions (step SD), and the optimum distribution of seek is set by referring to the shortest standard time and the rotation condition parameter stored in the ROM table 30E. (Step S
E)). That is, the acceleration current _IDR , the maximum speed _VMAX , and the deceleration start speed _VSR are set. These setting conditions are stored in the setting condition storage unit 30 of the memory unit 30C.
Stored in D.

After this operation, a drive instruction is issued from the drive instructing section 30G based on an instruction from the drive condition setting section 30A,
The direction signal indicating the acceleration direction is the VCM driver 4
Is output to 0, the current value control signal based on the value of the acceleration current I _DR stored in the setting condition storage section 30D is outputted to the servo control unit 42. The servo control unit 42 generates a current value control signal based on the input signal,
This is output to the VCM driver 40. In the VCM driver 40, as shown in FIG.
The acceleration current I _DR is energized at 2. As a result, the accelerated movement of the heads 12 and 14 is started (step SF).

This state is shown in FIG. 4, and the heads 12 and 14 are accelerated by the acceleration current _IDR shown in FIG. 4B as shown in FIG. The head speed at the time of acceleration is calculated by the speed calculation unit 30B, and the calculation result is output to the speed determination unit 30F. The speed determination unit 30F compares this head speed with the maximum speed V _MAX stored in the setting condition storage unit 30D, and determines whether the head speed has reached the maximum speed V _MAX (step SG). Then, when the maximum speed V _MAX is reached, the fact is notified to the drive instructing unit 30G. In the drive instructing unit 30G, a current value control signal for stopping the output of the acceleration current I _DR is output to the servo control unit 42, and a short signal is sent to the VCM driver 4.
It is output to 0.

Then, the transistor Q5 of the VCM driver 40 is turned off by the current value control signal of the servo control unit 42 to stop the energization of the voice coil 112, and the switch SW is turned on to short the voice coil 112. (Step SH, FIG. 4
(See (B)). Therefore, the moving voice coil 112
A counter electromotive force is generated by the action of the magnetic field of the magnet, and the heads 12 and 14 are decelerated (see FIG. 4A).

Similarly, the head speed during deceleration is also calculated by the speed calculator 3.
0B is calculated, and the speed determination unit 30F compares the head speed with the deceleration start speed V _SR (step SI). When the deceleration start speed V _SR is reached (see FIG. 4A), the fact is notified to the drive instructing unit 30G. In the drive instruction unit 30G, the ROM table 30
The deceleration table of E is referred to, the logical value of the direction signal is inverted, and the corresponding deceleration current value is instructed (see (B) in the figure). As a result, in the VCM driver 40, a deceleration current flows in the opposite direction to the voice coil 112, and the heads 12 and 14 are decelerated (step SJ, see FIG. 4A). Then, after waiting for rotation, the access is terminated when the target position is reached (step SK, see FIG. 4).

Next, the drive condition setting unit 30A
The optimal distribution of the traffic will be described based on a specific example. An example
For example, the heads 12, 1 are located in the sector S1 of the current track T0.
Assuming that there is 4, there are tracks T0 to T100.
It is assumed that seek is performed and the data of the sector S30 is read.
In this case, the time T required for rotation to reach the target sector_SIs
It is expressed by the following equation (1). T_S= (Number of moving sectors / total number of sectors) · time for one rotation (1) In this example, the number of moving sectors is 30-1 = 29, and
The number of kuta is 48. Also, the number of rotations of the disc 100 is
Assuming 3600 rpm, the time for one rotation is 16.
It will be 66 msec. Substituting these into equation (1) gives T_S= ((30-1) / 48) ・ 16.66msec  ≈10 msec.

Next, referring to the ROM table 30E, the shortest standard time for seeking from the track T0 to T100 is obtained, and a value of 6 msec, for example, is obtained. The shortest standard time is the time required for the head to reach the target track position by performing maximum acceleration / deceleration as shown in FIG. Here, the remaining time of T _S is calculated as 10−6 = 4 msec. If the remaining time becomes 0, it means that the head has to move to the target track before the target sector arrives. Therefore, maximum acceleration and maximum deceleration are performed as in the conventional example of FIG. Be seen.

In this example, the remaining time is 4 msec. Therefore, first, add half of the time, 2 msec, to the shortest standard time, 6 msec, and seek / decelerate the seek time of 8 ms.
The acceleration current I _DR is set to a value of 3/4 of the maximum value so as to be ec, and the deceleration current I _SR is also set in the ROM table 30.
It is set by multiplying the value of the deceleration table of E by a factor of 3/4. That is, the conditions are set as shown by the dotted line in FIG.
The coefficient of 3/4 takes into consideration the rotation condition parameter described above. Next, in addition to this condition,
A time of 3/4 of 2 msec of the remaining rotation waiting time, that is, 1.5 msec is set as the time when the movement is delayed due to the short circuit of the voice coil 112.

Further, the maximum speed V _MAX and the deceleration start speed V _SR are set in consideration of these time data and the rotation condition parameters. In the example of FIG. 4, a condition is set so that short-circuiting of the voice coil 112 starts at a time point of 3.2 msec, where deceleration starts at 4 msec after originally starting seek as shown by a dotted line. The brake caused by the short circuit of the voice coil 112 is an open loop having no feedback loop, and the deceleration due to the short circuit may be different from the expected one due to the variation of the rotation condition parameter and the temperature characteristic. However, at the final stage of the seek, since the normal deceleration seek using the deceleration table is performed, the inconvenience due to such variations and temperature characteristics does not occur. In particular, even if there is an external shock such as vibration, since the head speed is monitored, it is possible to make a good transition to the deceleration loop.

As described above, according to this embodiment, the seek control is performed within a range in which the substantial access time including the rotation waiting period does not become long. And the graph of FIG.
As is clear from a comparison of the graphs in FIG. 8A, if the areas = head movement amount are the same, the peak is reduced in this embodiment because the extra time is effectively used. This means that the instantaneous maximum electric power accompanying the head drive becomes small. Also, the power consumption associated with the head drive corresponds to the area of the graph of FIG.
As is clear from a comparison between the case of the dotted line and the case of the solid line in the figure, since the deceleration is performed by the voice coil short circuit, the speed is greatly reduced in this embodiment. In addition,
In this embodiment, the limit of the current value during acceleration or deceleration is set to V
This is performed by the transistor Q5 (see FIG. 2) of the CM driver 40. Therefore, power loss occurs due to the collector-emitter voltage, but the power consumption is greatly reduced as a whole.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, in the first embodiment, the power loss due to the transistor at the time of current limitation occurs, and the faster the head speed at the start of deceleration, the larger the counter electromotive voltage due to the voice coil short-circuit and the slower This is because it is advantageous to. The configuration of this embodiment is similar to that of the first embodiment, but the setting method in the drive condition setting unit 30A is different.

In the present embodiment, the maximum current I _MAX is set as the acceleration current I _DR , and this is applied to the voice coil 112 to accelerate it. Then, when the maximum speed V _MAX is set in the same manner as in the first embodiment, the voice coil 112 is short-circuited and deceleration is performed by the counter electromotive voltage. Further, when the deceleration start speed V _SR is set in the same manner as in the first embodiment, the ROM table 30E
The deceleration current of the deceleration table is applied to the voice coil 112 as it is (that is, the maximum current I _MAX ) to perform deceleration control. After that, when the sector reaches a few sectors before the target sector, rotation waiting is performed until the target sector position is reached, and then reading or writing of data is started.

For example, the heads 12, 1 are currently in the sector S1.
4 is located, seek from track T0 to T100, and further access sector S30 to read the data. The access time is 10 msec as in the case described above. The shortest standard time for seeking from track T0 to T100 is 6 msec.
And the remaining time is 4 msec. In this embodiment, the remaining time is 4 msec and the access time is 10 msec.
On the other hand, the seek time for acceleration / deceleration is 6 msec.
_So that the maximum current I _MAX is the acceleration current I _DR
And the deceleration current I _SR is also set as the ROM table 30E.
The maximum value is set using the deceleration table of. That is, the condition is set as shown by the dotted line in FIG.

Next, in addition to this condition, a time 3/4 of the remaining rotation waiting time of 4 msec, that is, 3 ms.
ec is set as the time delaying the movement due to the short circuit of the voice coil 112. The shorter the access time is, the shorter the voice coil short time is (the same applies to the above embodiment). Further, the maximum speed V _MAX and the deceleration start speed V _SR are set in consideration of these time data and the rotation condition parameters. In the example of FIG.
The condition is set so that short-circuiting of the voice coil 112 starts at a point of 1.8 msec where the seek is originally started and deceleration starts at 3 msec as indicated by a dotted line. It should be noted that it is the same as in the first embodiment that no inconvenience due to variations in the rotation condition parameters and temperature characteristics occurs.

As described above, according to this embodiment, like the first embodiment, the seek control is performed within a range in which the access time including the rotation waiting period does not become long, and the instantaneous maximum power accompanying the head drive is obtained. Becomes smaller, and the power consumption is significantly reduced. Voice coil 1 in this embodiment
Since the applied current of 12 is the maximum current in both acceleration and deceleration, the current value is not controlled. Therefore, VC
Since the transistor Q5 of the M driver 40 is not necessary, there is no power loss due to it.

<Other Embodiments> The present invention is not limited to the above embodiments, and includes, for example, the following. (1) The number of tracks, the number of sectors, the head acceleration / deceleration time, and the like shown in the above embodiment may be appropriately set as necessary. Also, the circuit configuration can be modified in various ways so as to achieve the same effect. (2) The drive characteristic data of the table and the actuator to be referred to when setting the acceleration / deceleration head drive conditions may be changed as necessary. For example, two deceleration tables may be used, one for short distance and one for long distance. (3) As a target to which the present invention is applied, a hard disk drive is a preferable example, but the present invention can also be applied to head drive in a drive device such as a flexible disk or an optical disk.

[0040]

As described above, according to the head driving device of the present invention, the coil of the actuator is short-circuited within the access time to decelerate the accelerated head. There is an effect that the head can be moved satisfactorily in a short time with reduced power consumption.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a head drive device according to the present invention.

FIG. 2 is a circuit diagram showing a configuration example of a VCM driver in the embodiment.

FIG. 3 is an explanatory diagram showing functional blocks of a microcomputer in the embodiment.

FIG. 4 is a schematic time chart showing the operation of the embodiment.

FIG. 5 is a flow chart showing an operation of the embodiment.

FIG. 6 is a schematic time chart showing the operation of the second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an example of a head driving actuator.

FIG. 8 is a time chart showing the operation of a conventional head drive.

[Explanation of symbols]

12, 14 ... Head, 16 ... R / W amplifier, 18 ... R /
W controller, 24 ... Hard disk controller,
30 ... Microcomputer, 30A ... Driving condition setting unit (driving condition setting unit), 30B ... Speed computing unit (speed detecting means), 30C ... Memory unit, 30D ... Setting condition storage unit, 3
0E ... ROM table, 30F ... Speed determination section (drive control means), 30G ... Drive instruction section (drive control means), 34 ...
Spindle motor, 36 ... SPM driver, 40 ... VC
M driver (drive control means), 42 ... Servo control section, 1
00 ... disk, 104 ... rotary actuator, 1
10 ... Voice coil motor, 112 ... Voice coil.

Claims (1)

[Claims] 1. A head drive device for controlling energization of a coil of an actuator to move a head on a disk to be accessed, which is required for the head to access from a current position on the disk to a target position. Drive condition setting means for determining an access time according to the above, and considering drive characteristics of the actuator within the range of this value, and setting drive conditions including deceleration due to short circuit of the coil,
A speed detecting means for detecting a moving speed of the head, and a drive control means for carrying out energization of an acceleration current of the coil, short-circuiting and energization of a deceleration current based on the driving condition according to the head moving speed detected thereby. A head drive device characterized by being provided.