JPH0814948B2 - Head position controller for disk storage device - Google Patents

Description

Detailed Description of the Invention TECHNICAL FIELD OF THE INVENTION

The present invention is a head position control device for a disk storage device such as a fixed disk device, which detects an off-track amount of a head position from a read signal of servo information written on a disk surface, and based on the detected value The present invention relates to a drive circuit for an operating actuator, which is provided with a control command value for finely adjusting its rest position to correct and control the off-track amount.

[Prior art and its problems]

In the aforementioned disk storage device, as is well known, each disk surface is provided with a large number of tracks, and in order to record information on or read information from the tracks, the head is placed at a correct position on a predetermined track. I have to put it in. The head is positionally controlled in the radial direction of the disk by an actuator for its operation. As the actuator for this purpose, a stepping motor having a multi-phase structure, typically a two-phase structure, is used as is well known. By repeatedly applying a predetermined number of drive signals to the head, the head can be moved to a desired track. The movement control of the head is, so to speak, an open loop type position control of the head, and it is not possible to accurately position the head at the normal position of the center of the track by such position control, and some off-track amount is always It can remain,
In the conventional simple disk storage device, by widening the radial width of the track, it is possible to read and write information without much trouble even if a small amount of off-track remains. However, when the radial width of each track is narrowed or the radial pitch between the tracks is reduced in order to increase the recording capacity of the disk storage device as in recent years, the information in the track is normally read and written. Had to accurately control the head to the normal position of the track without the amount of off-track. For this reason, servo information for detecting the head position is previously written on the disk surface, the above-mentioned off-track amount is detected from the read signal of this servo information, and then the actuator is arranged to eliminate this off-track amount. So-called closed loop control for controlling the head has come to be adopted for head position control. As a method for writing the servo information on the disk surface and a means for detecting the off-track amount from the read signal thereof, some publicly known technologies have been already known. It is possible to detect with. On the other hand, it is necessary to control the rest position of the head, and hence the actuator, and this is also possible by a known means. For example, when the actuator is a two-phase stepping motor, it is well known that two heads are provided. By controlling the relative ratio of the values of the phase currents flowing in the phase coils, the stationary position of the rotor can be controlled with high accuracy as a kind of torque motor. Therefore, in the position control of the closed loop type head, first, a predetermined number of drive signals are given to the actuator to operate as an original stepping motor to move the head to a desired track, and then the servo information is obtained. Is read through the head and the off-track amount is detected therefrom, and the relative ratio is selected so as to eliminate the detected off-track amount.
By applying the phase currents to the stepping motor,
The position of the head is controlled to the regular position on the desired track. In this case, it takes a long time for the head to actually stop at the regular position on the track after the head is moved near the desired track. Therefore, there is a problem that the access time to the recorded information in the disk storage device becomes long. The reason will be described below with reference to FIG. FIG. 7 shows an example of actual measurement of the time v of the speed v of the head, that is, the rotor of the stepping motor during the movement and position control of the head, and Tm in the figure represents the head movement period. During this time, as is known, a predetermined number of drive signals are sequentially applied to the stepping motor in accordance with a predetermined timing schedule, and the speed v thereof passes through a trapezoidal or triangular wave shape as shown in the drawing, and the head is desired. Will be moved near the truck. As shown in the figure, the speed v of the head is controlled so as to decrease as it approaches its stop position. However, after the time te when the last drive signal is applied to the actuator, the speed v of the head becomes as shown in the figure. Slight stop time Ts until the head stops due to the sequential decay
is necessary. Therefore, it is necessary to detect the off-track amount after the stop time Ts is set from the time te when the last drive signal is given, and in the illustrated example, the off-track amount is detected at the time td. The time required to detect the off-track amount is a time for the disk to make one rotation at the maximum, which is smaller than the stop time ts and can be ignored in the example of the figure. Next, the head position is position-controlled based on the off-track amount detected at this detection time point td, but the position control time Tc required for this is the same as the stop time Ts as shown in the figure, Is completely stationary at the normal position on the desired track for the first time at a stationary time ts after the time te when the last drive signal is given and after the stop time Ts and the position control time Tc are combined. Of course, at this stationary time ts, the off-track amount is detected again, and it is confirmed that the value is below the allowable limit.
Therefore, the illustrated example is a rather successful example, and if the off-track amount detected at the stationary time point ts exceeds the allowable limit, the position control is performed again,
Therefore, the position control time Tc is further required. In an actual example, as shown in the figure, it may take only one position control time Tc, but to put the head at the normal position of the track,
The position control time Tc is often required 2-3 times. Also, after the last drive signal is issued, the head may overshoot its stop position and vibrate back and forth, in which case the head does not stop completely during the given stop time Ts, and At the detection time point td, an erroneous off-track amount will be detected in the unstopped state, so that the position control time Tc will be required by repeating it. As described above, in the conventional closed-loop head position control, an unexpected time is consumed due to the head stop time and the position control time, which is a bottleneck for shortening the access time to the disk storage device. Was becoming. In actual experience, the so-called extra time for placing the head at the regular position of the track was at least the total of the stop time and the position control time.

[Object of the invention]

It is an object of the present invention to eliminate the bottleneck in shortening the access time of the disk storage device by minimizing the extra time consumed by the head stop time and position control time as described above.

[Points of the Invention]

In order to achieve the above-mentioned object, the present invention provides a disk (1) having a plurality of information recording tracks concentrically set on the surface thereof and servo information indicating the center position of each track, and the disk surface. A head (2) for reading and writing the above information, an actuator (5) for operating the position of the head, a drive circuit (60) for driving the actuator in accordance with a control command value, and a reading circuit for reading and writing the information. A head moving means (40) for moving the head onto a target track via a drive circuit and an actuator;
An off-track amount detection circuit that reads the servo information indicating the center position of the target track through the head moved by the head moving means onto the target track and detects the off-track amount of the head based on the servo information. A head position control device for a disk storage device including (70) includes a storage unit (115) that stores in advance a correspondence relationship between an off-track amount and a control command value for correcting the off-track amount, Command value generating means (10) for generating a control command value corresponding to the off-track amount detected by the off-track amount detection circuit based on the correspondence relationship, and the off-track amount detected by the off-track amount detection circuit is within an allowable limit. A head that determines whether or not it is within the allowable range and gives a control command value generated by the command value generating means to the drive circuit when the allowable limit is exceeded. Position correction means (30) and storage areas (111 to 11) corresponding to the plurality of tracks.
And a command value storage means (20) for storing a control command value for giving the off-track amount determined by the head position correction means to be within an allowable limit in the corresponding storage area. The correction means, when the head is moved onto the target track, controls the command value stored in the storage area corresponding to the target track by the command value storage means before detecting the off-track amount. It is characterized in that it includes means for supplying to a drive circuit. The control command value generated by the above-mentioned command value generating means basically designates the stationary position of the actuator. For example, when the actuator is a two-phase stepping motor, the two phase currents It is a command value that specifies the value. As is well known, the stationary position of the rotor of this type of multi-phase stepping motor is determined by the angular position of the combined vector of the phase currents, and the reference stop position of the rotor is the entire circumference of the electrical angle vector diagram. Corresponding to the reference angular position divided into a plurality of equal parts, usually the phase current command value corresponding to this reference angular position is sequentially given to the actuator as a drive signal for moving the head to a desired track. However, the stop angle position of the rotor of the stepping motor specified by each drive signal,
Therefore, the head stop position is generally slightly deviated from the normal position, which is the center of the desired track,
This appears as the above-mentioned off-track amount. Therefore, the control command value in the present invention commands an angular position deviating from the reference angular position on the electrical angle vector diagram in order to correct this off-track amount, and is a function of the off-track amount. The command value generating means is required to generate the control command value as a function of the detected off-track amount, and it must match the controlled characteristics of the actuator. Further, since this control command value is generally a non-linear function of the off-track amount, such a control command value based on the controlled characteristic of the actuator is stored in advance for each off-track amount and detected. The stored value may be read out as the control command value by the command value generation means according to the off-track amount. Furthermore, in practice, the above-mentioned function is often regarded as common for the angular reference angular position on the electrical angle vector diagram, so only the deviation value from the command value that specifies each reference angular position is used as the control command value. By storing, the control command value can be set regardless of the reference angular position,
The storage area required can be minimized. The off-track amount detected as the deviation of the head stop position from the normal position usually differs for each track depending on the state of mechanical connection with the actuator of the head. It was found that almost the same off-track amount was detected for each head movement operation unless the driving conditions of No. fluctuate extremely. Therefore, in the present invention, paying attention to this point, the control command value generated by the command value generation means is stored in the command value storage means on the basis of the off-track amount detected subsequently to the movement of the head. In the next movement operation, the stored previous control command value is read by the head position correcting means and given to the actuator without waiting for the detection of the off-track amount.
Therefore, the actuator will be given the most suitable control command value from the beginning, and in many cases the position correction control will be done only once, and the head will almost certainly be moved to the regular position on the track after one position control time. It becomes possible to stand still. Also, the control command value to be given to the actuator is the same as the above-mentioned drive signal designating each stop position of the head, but has the same character, so instead of the drive signal before stopping the head, Advantageously, the control command value is given to the actuator. In this case, the head can be stopped at the regular position of the track after the above-mentioned stop time after the last drive signal, that is, the control command value is given, and in many cases, the position control time is completely unnecessary. There may be a plurality of control command values given to the actuator instead of the drive signal, but even if it is one, it is possible to obtain the effect of omitting the position control time in most cases. Since the off-track amount of the head stop position from its normal position is often different for each track as described above, it is desirable to store the control command value by the command value storage means for each track. Since a disk storage device usually has a plurality of disk surfaces and the off-track amount often differs for each disk surface, it is preferable to store the control command value for each device surface. Further, as the control command value, when the actuator is a two-phase stepping motor, two control command values corresponding to two phase currents are stored by the command value storage means. Other preferred embodiments of the present invention are described in the next section.

Examples of the invention

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional system diagram schematically showing various means of the present invention together with a disk storage device and its peripheral circuits.
In the upper left part of the figure, the side surface of a fixed disk device having two disks 1 is schematically shown as an example of a disk storage device. The disk 1 is fixed to a spindle shaft 1a and is driven at a high speed and a constant speed by a spindle motor 1b. Although not shown in the figure, hundreds of information recording tracks are concentrically set on each surface of the disk 1, and the head 2 for reading and writing information on the tracks corresponds to each disk surface. And is carried by the moving carriage 3. The carriage 3 is guided on a base plate 4 by a guide 3a so as to be movable in the left-right direction in the figure, and mechanically via a capstan 5d connected to a rotor 5c of an actuator 5 and a flexible thin plate 3b. It is connected. Since the thin plate 3b has its both ends fixed to the carriage 3 and its intermediate portion is wound around the capstan 5d, when the actuator 5 is driven, the capstan 5d rotates, and accordingly, the carriage 3 and accordingly it is carried. The radial position of the head 2 with respect to the disk 1 is controlled in the left-right direction in the drawing. As is well known, servo information for detecting the position of the head 2 by being interrupted in a part of the circumferential direction of the track is written on the surface of the disk 1 so that the head 2 can read it at any time. Be present. The illustrated actuator 5 is a two-phase stepping motor, which includes two phase coils 5a and 5b, and a phase current to both phase coils is supplied from a drive circuit 60. The drive circuit 60
May be a known one, and in the example of the figure, it has a two-stage configuration of a PWM signal generation circuit 61 and two switch circuits 62a and 62b, and receives a drive signal DD. The drive signal DD includes a current designating signal DDv and a phase designating signal DDp, which are multi-bit digital signals, and the PWM signal generation circuit 61 receives the former and issues a PWM signal having a pulse width corresponding to the former. The phase designation signal DDp is, for example, a 4-bit digital signal, and the switch circuits 62a and 62b are alternately turned on or turned on or off at the same time according to the signal value, and the current from the DC source indicated by +- PWM for the phase coils 5a and 5b of the actuator 5
Power is supplied in the positive and negative directions designated by the phase designation signal DDp within the time designated by the signal. On the other hand, the information recorded on the track of the disk 1, especially the servo information, is read out via the head 2 and read out as a read signal.
The signal is supplied to the head switching circuit 6 as RS, and the head switching circuit 6 outputs the read signal RS from the head designated by the selection signal SL and supplies it to the amplifier circuit 7. The amplified output from the amplifier circuit 7 is given to the off-track amount detection circuit 70, and the off-track amount detection circuit 70 detects and outputs the off-track amount OT. The off-track amount detection circuit 70 differs depending on the servo information writing mode,
Any known circuit may be used to implement the present invention. Reference numeral 50 denotes a controller circuit attached to or incorporated in the disk storage device, for example, a small-scale microcomputer, which issues the above-mentioned selection signal SL. The means constituting the present invention are included in the computer circuit 100 shown in the lower part of the figure, and its hardware configuration is shown in FIG. As shown in the figure, the computer circuit 100 includes CPUs 1 that are interconnected by a bus 101.
It may be a normal one composed of 02, ROM 103, RAM 110, input port 104, output port 105 and the like. In the figure, the mechanical section 200a of the disk storage device 200 and the attached circuit section 200b are shown.
The drive circuit 60, the off-track amount detection circuit 70, and the controller circuit 50 as well as the drive circuit 80 for the spindle motor 1b are included in the latter. Further, the spindle motor 1b generates an index pulse IP that gives the timing of reading the read signal RS in accordance with the rotation of the disk 1, and the controller circuit 50 and the computer circuit 100.
And given to. Returning to FIG. 1, the command value generating means 10 included in the computer circuit 100 and constituting the present invention cooperates with the command value storage area 115 set in the RAM 110. In the command value storage area 115, control command values are stored for each off-track amount OT as shown in FIG. 3, and the control command values in this example are drive signal values corresponding to each reference angular position. It is stored as a deviation value ΔDD from. Such control command values are respectively stored for m off-track amounts indicated by 1 to m as shown in the figure, and each control command value is 2 for the actuator 5 as shown for the first one.
It is composed of two pieces of data 1a, 1b, etc. corresponding to the individual phase coils 5a, 5b. A storage area for the command value storage means 20 is also set in the RAM 110 as shown in FIG. 1, and its details are shown in FIG. As shown in the figure, multiple storage areas are set for each head number HN corresponding to multiple disk surfaces of the disk storage device.
Each of 111 to 114 stores a control command value for each of n track numbers TN. The control command value in this example stored here is the deviation value ΔDDf corresponding to the control command value stored in the command value storage area 115, and two data 1a, 1b, etc., respectively, as before. Consists of. As described above, the control command value or its deviation value stored in these areas 111 to 114 is the value used for the previous position control, but initially it is the value as the drive signal or its deviation value is 0 value. Suffice to remember. The head moving means 40 shown in FIG. 1 is for a normal disk storage device,
A command to move the head to a target track is received from the controller circuit 50 in the form of a step pulse SP or a moving direction command TD, and a drive signal DD corresponding to this is issued to the cover unit 60.
The storage area 116 set in the RAM 110 cooperates with this,
Stores the track number TN where the head is currently located. Although a counter 41 for receiving the step pulse SP is shown attached to the head moving means 40 in the figure, the function of the counter 41 is often incorporated in the head moving means 40 in many cases. The counter 41 shown in the figure integrates the step pulse SP and outputs a movement command number SPN indicating the number of tracks on which the head 2 should be moved. Incidentally, the computer circuit 100 including these various means, even if it is an independent circuit as shown,
It may be the computer itself that uses the disk storage device, or it may be incorporated into the controller circuit 50 attached to the disk storage device if it has the capability. Now that the description of the hardware configuration of the head position control device for a disk storage device according to the present invention has been completed, its operation will now be described with reference to FIG. In addition,
The operation flow shown in this figure is such that the control command value generated by the command value generation means 10 is a deviation value, and the head position correction means
It should be noted that although 30 corresponds to the embodiment that is activated at the end of the movement period of the head to the target track, the present invention can be implemented in various modes, not limited to such a specific embodiment. . The operation flow of the head moving means 40 shown on the left side of FIG. 5 is the same as that in the conventional apparatus except for the start timing of the head position correcting means 30 described above. It will be explained from this part because it is slightly related to various means to be performed. As described above, since the head movement command is issued from the controller circuit 50 attached to the disk storage device, the head moving means 40 always checks the presence or absence of the step pulse SP as the movement command in step S1, and the step pulse SP When received, the number of pulses is integrated in step S2. This step pulse SP is usually 1 as is well known.
The individual commands the movement of the pitch between tracks.
Since the presence or absence of the next pulse is determined in step S3 each time the pulse is counted, the integration up to that point becomes the movement command number SPN when the arrival of the pulse ends. The flow of steps S1 to S3 may be performed by software as described above or by a separately provided counter 41 as shown in the figure. Number of movement commands
In step S4 after the SPN is confirmed, the movement direction command TD output from the controller circuit 50 in the same manner as the step pulse SP is read. The flow from step S5 onward is the flow of head movement operation, and in this first step S5, 1 is set to the auxiliary variable i. In step S6, as described above, the drive signal DD including the current designation signal DDv and the phase designation signal DDp is issued to the cover unit 60. Of course, the drive signal that matches the current position of the head 2 is the storage area 116. The head is moved by one track pitch each time the cover unit 60 receives the drive signal DD once. In step S7, the auxiliary variable i is compared with the value obtained by subtracting 1 from the movement command number SPN, and if it is smaller than this value, 1 is added to the auxiliary variable i in step S8 and the flow is returned to step S6. Each time the step S6 is executed, the head is moved by one track pitch. During this time, the track number TN indicating the current position of the head 2 in the area 116 is also updated each time the head 2 moves between tracks. When the head 2 is moved to the track immediately before the target track, the determination result of step S7 becomes positive, and the flow moves to the operation as the head position correcting means 30. That is, in this embodiment, the last drive signal DD is not issued, and instead the control command value is given from the head moving means 40 to the drive circuit 60. In this first step S9, the head selection signal SL issued from the controller circuit 50 is read. As described above, since the control command value is stored in the command value storage means 20 for each head number and each track number, in step S10 the selection signal SEL read in the previous step S9, that is, the head number HN and the storage area. The control command value based on the track number TN in 116, in this case, the previous deviation value ΔDDf is read. The subsequent step S11 is a step of determining the flag F. Of course, since the flag F is 0 at first, the flow jumps to step S13, and here the deviation value ΔDDf of the control command value read from the command value storage means 20.
The current designation signal DDv is calculated based on Next step S
At 14, the current designating signal DDv and the phase designating signal DDp read from the area 116 are combined to form a drive signal DD, which is transmitted to the drive circuit 60. As a result, the head 2 is driven to the target track based on the previous drive signal,
Since the movement of the head requires a certain time period corresponding to the stop time Ts, the flow is stopped for a small time period ΔT in the subsequent step S15. As is well known, the setting of such a small time period can be facilitated by so-called soft timer means. In step S16 after the lapse of the small time period ΔT, a command to detect the off-track amount OT is transmitted to the off-track amount detection circuit 70. Of course, before this command reaches the off-track amount detection circuit 70, the head switching circuit 6 is switched to the designated head by the selection signal SL, so the off-track amount detection circuit 70 reads from this designated head. Signal RS
Is immediately read through the amplifier circuit 7, and the off-track amount OT is detected in a known manner. Since this detection does not take much time, the off-track amount OT detected in the next step S17 is read from the off-track amount detection circuit 70, and in the next step S18, this off-track amount is 0 or less than the allowable limit. Or not. If the off-track amount exceeds the allowable limit, the flow moves to the operation as the command value generating means 10, and if it is less than the allowable limit, the command value storing means 20
Enter the operation as. Unfortunately, if the detected off-track amount exceeds the allowable limit, the flag F is set to 1 in the first step S19 of the command value generating means 10. Subsequently, in step S20, the control command value corresponding to the off-track amount OT previously read in step S17, in this example, the deviation value ΔDD thereof is read from the above-mentioned storage area 115, and the flow is returned to step S11. Since the flag F has already been set to 1, this time the flow moves to step S12, where the deviation value ΔDDf of the previous control command value is set.
The deviation value ΔDD of the control command value generated from the command value generating means 10 is added to. As a result, the previous deviation value ΔDDf is rewritten to the current deviation value, and based on this, step S13
The head position is corrected and controlled by ~ S15, and step S
In 16 to S18, check whether the off-track amount is below the allowable limit. Of course, when the off-track amount still exceeds the allowable limit, the command value generating means 10 is activated again, and the re-correction operation by the head position correcting means 30 is repeated, but in many cases, even if it is bad, the correction is performed once. Since the off-track amount is corrected by the control, the flow starts the operation as the command value storage means 20 from step S18. In the first step S21 of the operation of the command value storage means 20, the flag F is returned to 0, and in the next step S20, the control command value that is successfully corrected and controlled so that the off-track amount is below the allowable limit,
In this case, the deviation value ΔDDf is stored in the command value storage means 20 as the current control command value. Of course, the deviation value ΔDDf as the control command value at this time is the same value as that read from the command value storage means 20 when the off-track amount is below the allowable limit from the beginning, but the command value generation means When 10 is activated and the deviation value ΔDDf is updated as described above in response to this, the stored value of the command value storage means 20 is the deviation value ΔDDf as the latest control command value for which the head position correction control has succeeded. Can be rewritten as The operation of the present invention is completed by this step S22. FIG. 6 shows an actual measurement example of the change over time of the movement of the head 2 when the present invention is carried out, in comparison with FIG. 7 described above in the case of the prior art, in which the control command value is set as the final drive signal. Corresponds to the previous embodiment given by In the illustrated example, the off-track amount is below the permissible limit by giving the control command value as the drive signal only once, and after the small time period ΔT from the time te when the control command value is given as the last drive signal. Succeeded in stopping the head at the proper position on the target track.

【The invention's effect】

As described above, according to the present invention, the control command value that succeeded in the head position correction control last time is stored in the command value storage means, and at the time of this correction control, the stored previous control Since the head position correcting means reads out the command value and the head position correction control is performed on the basis of the command value, the probability that the off-track amount from the normal position of the head track falls within the allowable limit by one correction control. Is very high, and it is not necessary to perform correction control after detecting the off-track amount many times as in the conventional case, and the bottleneck for shortening the access time of the disk storage device can be substantially eliminated. Further, even if the off-track amount fails within the allowable limit by one correction control, the control command value for which the correction control succeeds is stored in the command value storage means as the current control command value. Will almost certainly only need to be done once. This point is also proved by the experimental results of the device of the present invention, and in the steady state where the disk storage device is thermally saturated, the first correction control failure is rarely experienced. Further, as the most advantageous embodiment of the present invention, if the correction control is applied at the end of the moving time of the head, the head is almost certainly controlled to the regular position of the track at the time of the first stop. It is possible to eliminate the need to repeat the stop of the head and the movement for correcting the position at the time of controlling the position of the head to the regular position as in the device.

[Brief description of drawings]

FIG. 1 is a functional system diagram showing various means of a head position control device of a disk storage device according to the present invention together with the disk storage device and its peripheral circuits, and FIG. 2 exemplifies a configuration corresponding to FIG. 1 in terms of hardware. FIG. 3 is a block circuit diagram, FIG. 3 is an allocation diagram of a memory exemplifying the content of a command value storage area which cooperates with the command value generating means in the present invention, and FIG. 4 is a memory exemplifying the content of the command value storage means in the present invention. Allocation diagram, FIG. 5 is a flow chart illustrating the operation of various means constituting the present invention together with the head moving means, and FIG. 6 is a diagram showing the time course of the movement of the head when the present invention is carried out. The figure is a diagram showing the time course of the movement of the head in the conventional apparatus, corresponding to FIG. In the figure, 1: disk, 2: head, 5: actuator configured as a 2-phase stepping motor, 5a, 5b: phase coil of the stepping motor as an actuator, 6: head switching circuit, 10: command value generating means, 20 : Command value storage means, 30: Head position correction means, 40: Head movement means, 41: Counter cooperating with head movement means, 50: Controller circuit, 60: Drive circuit, 70: Off-track amount detection circuit, 100: Computer circuit, 1
10: RAM of computer circuit, 111 to 114: storage area in RAM constituting command value storage means, 115: command value storage area in RAM cooperating with command value generating means, 116: cooperating with head moving means Storage area in RAM, DD: drive signal or drive signal as a control command value, ΔDD: deviation value as a control command value generated by command value generation means, ΔDDf: control stored in command value storage means Its deviation value as command value, DDp:
Phase designation signal included in drive signal, DDv: Current designation signal included in drive signal, HN: Head number, OT: Off-track amount,
S1 to S8: Operation steps as head moving means, S9 to S1
8: Operation step as head position correction means, S19 to S2
2: Operation step as command value generation means, S21 to S22: Operation step as command value storage means, ΔT: Small time limit, Tc:
Position control time, TN: track number, TS: stop time, t: time, v: head speed.

Claims (1)

[Claims] 1. A disk on which a plurality of information recording tracks are concentrically set on the surface and servo information indicating the center position of each track is written, and a head which reads and writes information on the disk surface. An actuator that operates the position of the head, a drive circuit that drives the actuator according to a control command value, and a head moving unit that moves the head onto a target track via the drive circuit and the actuator when reading and writing the information. And an off-track amount for detecting the off-track amount of the head based on the servo information by reading the servo information indicating the center position of the target track through the head moved on the target track by the head moving means. In a head position control device of a disk storage device including a detection circuit,
It includes a storage unit that stores in advance a correspondence relationship between the off-track amount and a control command value for correcting the off-track amount, and corresponds to the off-track amount detected by the off-track amount detection circuit based on the correspondence relationship. Command value generating means for generating a control command value and whether or not the off-track amount detected by the off-track amount detecting circuit is within an allowable limit, and the command value generating means generates when the off-track amount exceeds the allowable limit. A head position correcting means for giving a control command value to the drive circuit and a storage area corresponding to each of the plurality of tracks, and the off-track amount determined by the head position correcting means to be within an allowable limit. Command value storage means for storing a given control command value in a corresponding storage area, wherein the head position correction means is provided for moving the head onto a target track. A disk storage device, characterized in that the command value storage means includes means for giving a control command value already stored in a storage area corresponding to the target track to the drive circuit prior to detection of the off-track amount. Head position control device.