JP2942130B2 - Magnetic disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive for recording / reproducing information on / from a magnetic disk by using a magnetic head, and more particularly, to a magnetic disk drive having a corrector for accurately setting a position where the magnetic head should be driven. To a magnetic disk drive.

[0002]

2. Description of the Related Art In general, a magnetic disk drive comprises a magnetic disk which is rotated at a high speed by a drive motor, and a magnetic head which records information on the magnetic disk and reproduces information recorded on the magnetic disk. And a magnetic head drive mechanism for moving the magnetic head at a high speed in a radial direction of the magnetic disk to access a desired track on the magnetic disk. A control unit for generating a digital output for moving the magnetic head in a radial direction of the magnetic disk; and a digital / analog for converting the digital output generated by the control unit to an analog voltage. And a voice coil motor driver to which the analog voltage is supplied and which moves the magnetic head onto a predetermined track in the radial direction of the magnetic disk at a high speed in accordance with the analog voltage.

In this case, when a command is supplied from the outside or the command information recorded on the magnetic disk is read by the magnetic head, the control unit outputs a digital output based on the content of the command. And supplies this digital output to the digital / analog converter. The digital / analog converter converts the digital output to a corresponding analog voltage, and supplies the analog voltage to the voice coil motor driver.
Further, a reference voltage is supplied to the voice coil motor driver, and the voice coil motor driver operates in a direction corresponding to a magnitude (polarity) of a voltage value of the analog voltage with respect to the reference voltage, and a magnitude of the voltage. Well,
That is, the voice coil motor is rotated by a displacement amount corresponding to the difference from the reference voltage, whereby the magnetic head is moved at a high speed onto a predetermined track in the radial direction of the magnetic disk. .

[0004]

However, in a known magnetic disk drive of the ramp loading type, in which the magnetic head separates from the magnetic disk when the magnetic disk device is stopped, an arm having the magnetic head inclined at the time of startup, that is, a ramp, is used. It is necessary to shift from the (spreader) portion to the magnetic disk, and at the time of the shift, the magnetic head cannot read the servo information on the magnetic disk. It is not possible to set an appropriate transition speed or perform different speed management at each position after the magnetic head starts to transition. For this reason, when the magnetic head moves from the ramp portion onto the magnetic disk, the magnetic head contacts the magnetic disk because its speed is too slow, or collides with the magnetic disk obliquely because the speed is too fast. There is a problem that it is.

On the other hand, CSS (Constant Start)
A data area where the magnetic head can reliably read servo information from an area where servo information is not recorded on the magnetic disk or an area where servo information cannot be accurately detected, even on a known magnetic disk of the stop) type. Since the servo information cannot be read at the time of shifting to the above, there is also a problem that the speed control of the magnetic head cannot be performed.

Also, in each of the known magnetic disk devices, since the values of various components and circuit elements constituting the magnetic disk device vary, the digital / analog converter has a center (center) voltage. And when the center voltage is supplied to the voice coil motor driver, the current of the voice coil motor driven by the voice coil motor driver is not always zero, and the current of the voice coil motor is not always zero. At zero,
That is, the neutral point of the voice coil motor output cannot be set on the digital / analog converter side, in other words, the neutral point offset processing of the voice coil motor output on the digital / analog converter side. Cannot be performed.

The present invention has been made to solve these problems, and has as its object to provide a neutral output of a voice coil motor.
Control point offset processing (digital / analog conversion)
To provide a magnetic disk drive that can be performed by the switching device.

[0008]

[0009]

In order to achieve the above object, the present invention provides a rotating magnetic disk and the magnetic disk
A magnetic head for recording / reproducing information to / from the magnetic head;
A control unit for generating a digital output for shifting the mode,
A digital converter that converts the digital output of the control unit to an analog voltage
And analog / digital converters and
Drive the chair coil motor to move the magnetic head
Voice coil motor that moves in the radial direction of the air disk
A magnetic disk drive having a driver.
When the magnetic disk drive is started, the voice coil
Ideal value or zero to make the drive current flowing to the motor zero
Outputs a digital output close to its ideal value to the digital / analog
To the log converter, at which time the voice coil mode
Power supplied from the data driver to the voice coil motor.
Voltage between the terminals of the voice coil motor caused by current flow
The digital output value.
Multiple times, and based on these measured terminal voltages,
The current flowing through the voice coil motor is substantially
The value of the digital output that becomes zero is calculated, and this
Digital output value when driving the voice coil motor
Means for setting the actual center output value in the control unit.

[0010]

[0011]

According to the above means, when the magnetic disk drive is started up
The control unit reduces the drive current flowing through the voice coil to zero.
Digital value of an ideal value or a value close to the ideal value
Generate an output and convert the digital output to digital / analog
Feed the converter, then the voice coil motor driver
The current is supplied to the voice coil motor via the. Also,
The control unit includes a voice coil generated by supplying the current.
Measure the voltage between the terminals of the motor and the measured value is zero
If it is determined that it is not zero,
Digital output that brings the voltage between terminals close to zero again
Occur. Next, this digital output is
Once supplied to the log converter, the voi
Voice coil motor via a coil motor driver
The current is supplied and the control unit
The voltage is measured again to determine whether the measured value is zero.
Determine. And the control unit outputs such digital output
Occurs, measures the voltage between the terminals of the voice coil motor, and
The determination of the measured value of
Digital output that minimizes or minimizes the current flowing
Force value, that is, the actual center value of the digital output
Can be The value of the digital output thus obtained
Thereafter, the power of the magnetic disk drive is turned off.
Now, the current for zeroing the driving current of the voice coil motor is
Used as a digital output indicating the actual center value.

[0012]

[0013]

Therefore, when the magnetic head is moved onto a predetermined track of the magnetic disk, the digital output indicating the actual center value for making the driving current of the voice coil motor zero is used as a reference. Irrespective of the variation in the components and circuit components constituting the data disk, the accuracy of the search processing for the data zone of the magnetic disk and the accuracy of the center value at the time of seeking can be significantly increased.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a magnetic disk drive according to the present invention. A hard disk drive of a ramp loading type is used as the magnetic disk drive. It has a drive circuit system for the voice coil motor as described above.

In FIG. 1, 1 is a hard disk (magnetic disk), 2 is a magnetic head, 3 is a head transfer mechanism, 4
Is a swing arm, 4a is a pivot of the swing arm 4, 5
Is a head support spring, 5a is a ramp portion, and 6 is a voice coil motor (VCM).

The hard disk 1 has its axial center attached to a rotating shaft of a disk rotating spindle motor (not shown) via a hub (not shown), and is rotated at a high speed by the rotation of the spindle motor. It is arranged and configured. The magnetic head 2 is attached to the tip end (free end) of the head transfer mechanism 3 and is appropriately moved in the radial direction of the hard disk 1 by the rotation of the head transfer mechanism 3 as indicated by a dotted line in the figure. The head transfer mechanism 3 includes a swing arm 4 that rotates about a support shaft 4a, and a head support spring 5 attached to a free end of the swing arm 4.
And a voice coil motor 6 for rotating the swing arm 4. The voice coil motor 6 has a required polarity and a driving current of a required magnitude is passed through the voice coil motor 6. The head transfer mechanism 3 is rotated via a motor 6 to move the magnetic head 2 to a predetermined track position on the hard disk 1. The ramp portion 5a is a holding member for separating the magnetic head 2 from the hard disk 1. When the magnetic head 2 is not operated (when the power is turned off), the head supporting spring 5 rides on the inclined ramp portion 5a, and the ramp portion 5a Is to be held.

The hard disk drive composed of the above-described components has a structure itself and an overall operation thereof.
Since both are known, a detailed description of the structure and operation will be omitted.

FIG. 2 is a block diagram showing a schematic configuration of a drive circuit system of a voice coil motor used in the magnetic disk drive according to the present invention.
FIG. 3 is a block diagram showing a specific configuration of a part of a drive circuit system of the voice coil motor shown in FIG. 2.

In FIG. 2, reference numeral 7 denotes a control unit (CPU);
a is a first analog / digital converter (A / D), 7b
Is a circuit offset correction unit, 7c is a speed correction unit, 7d is an integration circuit unit, and 7e is a second analog / digital conversion unit (A
/ D), 7f is a center value calculation unit, 7g is a center value holding unit, 8 is a digital / analog converter (D / A), 9 is a voice coil motor (VCM) driver, and 10 is a back electromotive force detection circuit. .

3 and 4, 11 is a bridge circuit, 11a is a motor winding of the voice coil motor 6, 11b is a sense resistor, 11c is a first resistor, 11d
Is a second resistor, 12 is a subtraction amplifier circuit, 12a is an operational amplifier, 12b is a first series resistor, 12c is a second series resistor, 12d is a feedback resistor, 12e is a shunt resistor, 13 is a reference voltage generating circuit, 13a is a first bleeder resistor, 13b is a second bleeder resistor, 14 is a reference voltage amplifier circuit, 14a
Is an operational amplifier, 14b is a first feedback resistor, 14c is an amplification rate setting resistor, 15 is a unit gain amplifier circuit, 15a is an operational amplifier, 16 is a filter circuit, and the other components are the same as those shown in FIG. Elements have the same reference numerals.

Then, as shown in FIG. 2, the control unit 7
First analog / digital converter 7a, circuit offset correction unit 7b, speed correction unit 7c, integration circuit unit 7d, second analog / digital conversion unit 7e, center value calculation unit 7
f, a center value holding unit 7g, and respective inputs of the first and second analog / digital converters 7a and 7e are connected to an output of the back electromotive force detection circuit 10;
Each output of the integrating circuit unit 7d and the center value holding unit 7g is connected to the input of the digital / analog converter 8.

As shown in FIGS. 3 and 4, the output of the digital / analog converter 8 is
The output of the voice coil motor driver 9 is connected to the input of the back electromotive force detection circuit 10 through the filter circuit 16 and the filter circuit 16. The unit gain amplifying circuit 15 is composed of an operational amplifier 15a connected in a 100% negative feedback manner.
0 comprises a bridge circuit 11 and a subtraction amplifier circuit 12. The bridge circuit 11 includes a motor winding 11 a (resistance value Rm) of the voice coil motor 6 and the sense resistor 1.
1b (resistance Rs), a first resistor 11c (resistance R1) and a second resistor 11d (resistance R).
2) and a subtraction amplifier circuit 12
Represents an operational amplifier 12a, a first series resistor 12b (resistance value Ra) connected in series to its inverting input, and a second series resistor 12c (resistance value R) connected in series to its non-inverting input.
a) and a feedback resistor 1 connected between its inverted input and output.
2d (resistance value Rb), its non-inverting input and reference potential point,
That is, a shunt resistor 12e (resistance value Rb) is provided between the output of the reference voltage amplifier circuit 14 and the shunt resistor 12e. The output of the reference voltage generating circuit 13 is connected to the input of the reference voltage amplifying circuit 14 and the non-inverting input of the operational amplifier 15a of the unit gain amplifying circuit 15, and the output of the reference voltage amplifying circuit 14 is the voice coil motor driver 9, the filter circuit 16, are respectively connected to the other ends of the shunt resistors 12e of the subtraction amplifier circuit 12.
The reference voltage generating circuit 13 includes a first bleeder resistor 13a and a second bleeder resistor 13b connected in series between a 5V power supply terminal. The reference voltage amplifying circuit 14 includes an operational amplifier 14a and an inverting input thereof. It has a feedback resistor 14b connected between the outputs, and an amplification factor setting resistor 14c connected between its inverted input and the ground point.

The output of the subtraction amplifier circuit 12 is connected to the input of the first analog / digital converter 7a. Further, as shown in FIG. 4, both ends of the motor winding 11a are connected to the second terminal. It is connected to the input of the analog / digital converter 7e.

Here, the operation of the drive circuit system of the voice coil motor in the magnetic disk drive of the present invention having the above configuration will be described with reference to FIGS.

When the magnetic disk drive is started (when power is turned on), the drive circuit system of the voice coil motor performs the following operation.

First, the head support spring 5 is moved to the ramp portion 5.
a, the control unit 7 sets an ideal digital value or a digital value close to the ideal digital value such that the current flowing through the voice coil motor 6 (motor winding 11a) becomes zero. The output is calculated by a center value calculator 7f, and the digital output is supplied to a digital / analog converter 8. At this time, the output digital value is held in the center value holding unit 7g. The digital / analog converter 8 converts this digital output into a corresponding analog voltage and supplies it to the voice coil motor driver 9 via the unit gain amplifying circuit 15 and the filter circuit 16. The voice coil motor driver 9 refers to the output voltage of the reference voltage amplifying circuit 14, that is, the reference voltage V2, and allows the voice coil motor 6 to flow a current corresponding to the analog voltage. At this time, the control section 7 converts the voltage generated at both ends of the motor winding 11a of the voice coil motor 6 into a digital value by the second analog / digital conversion section 7e and measures the voltage. When the current flowing through the voice coil motor 6 is not zero, the center value calculating unit 7f calculates again a digital output of another value that makes the current flowing through the voice coil motor 6 zero, and the value of the center value holding unit 7g is calculated. Is updated to another digital value, and this digital output is converted to a digital / analog converter 8.
To supply. The digital / analog converter 8 converts this digital output into a corresponding analog voltage and supplies it to the voice coil motor driver 9. The voice coil motor driver 9 similarly causes the current corresponding to the analog voltage to flow through the voice coil motor 6. Also at this time, the control unit 7 measures the voltage generated at both ends of the motor winding 11a of the voice coil motor 6, and when the voltage is not yet zero, as in the case described above, the voice coil motor 6 Calculate a digital output of another value such that the current flowing through the center value becomes zero, update the value of the center value holding unit 7g,
This digital output is supplied to the digital / analog converter 8, and the above-described operation steps are repeatedly executed.

When the current flowing through the voice coil motor 6 becomes substantially zero or when the current becomes minimum, the final digital output value generated by the control unit 7 is held at the center value. Then, the digital output value held here is set to the actual center output value when the voice coil motor 6 is driven until the power of the magnetic disk device is turned off. .

In this case, the value of the digital output generated by the control unit 7 is set to the initial value, that is, a direction in which the current flowing through the voice coil motor 6 is gradually and gradually reduced from an ideal value in design to zero. Set to increase or decrease,
When the current becomes zero or its conduction polarity is reversed, it is preferable to obtain the actual center output value, but it is set so that the value changes randomly from the initial value. At this time, the actual center output value may be obtained when the current becomes zero or the flow polarity thereof becomes minimum. When the actual center value is obtained, the head support spring 5 is placed on the ramp portion 5a and both are in contact with each other. Even if a current flows through the motor 6, the current is slight, and the voice coil motor 6 (swing arm 4) does not move due to the friction between the head support spring 5 and the ramp portion 5a. No back electromotive force is generated.

Subsequently, while the head supporting spring 5 is mounted on the ramp portion 5a, an offset coefficient described below is obtained. First, the control unit 7 generates a digital output value that is the actual center output value already obtained, and supplies the digital output value to the digital / analog converter 8. The digital / analog converter 8 converts this digital output into a corresponding analog voltage Vc and supplies it to the voice coil motor driver 9 via the unit gain amplifier circuit 15 and the filter circuit 16. Here, since the value of the digital output is the actual center output value, the analog voltage Vc is substantially equal to the reference voltage V2 supplied to the voice coil motor driver 9. The voice coil motor driver 9 includes the motor winding 1
The analog voltage Vc (= V2) is converted to the back electromotive force detection circuit 1 including the motor winding 11a of the voice coil motor 6 so that the current flowing through the first coil 1a becomes zero (or minimum).
Supply 0. That is, the voltage for causing the current to flow through the motor winding 11a is equal to the voltage of the bridge circuit 11 of the back electromotive force detection circuit 10.
In this case, any one of a connection point between the sense resistor 11b and the second resistor 11d and a connection point between the motor winding 11a and the first resistor 11c is provided. Also, the analog voltage Vc (= V2) is supplied, and as a result, the current flowing through the motor winding 11a becomes zero (or minimum). Here, even if there is a potential difference between one terminal of the bridge circuit 11 and a current flows through the motor winding 11a, the current is small, and the head supporting spring 5 mounted on the ramp portion 5a is moved. In a state where the voice coil motor 6 does not move, the voice coil motor 6 is not in a driving state, so that no back electromotive force is generated at both ends of the motor winding 11a, and the bridge circuit 11 is in a balanced state. Since the bridge circuit 11 is in an equilibrium state, almost no potential difference occurs between the other terminals of the bridge circuit 11, and the connection point between the sense resistor 11b and the motor winding 11a is connected to the second resistor 11d. Two output voltages V ₀₁ and V ₀₂ having substantially the same magnitude are generated at a connection point between the first and second resistors 11c. When there is a potential difference between one terminal of the bridge circuit 11 and the bridge circuit 11 is in an equilibrium state, the first resistor 11c and the second resistor 11c are set so that the two output voltages V ₀₁ and V ₀₂ become equal.
Although the resistance value of d is set, in reality, the two output voltages V ₀₁ and V ₀₂ are not completely equal. The reason is that the motor winding 11 forming the bridge circuit 11
a, sense resistor 11b, first and second bridge resistors 1
This is because each of the resistance values 1c and 11d has a variation (a deviation from an ideal value). Subsequently, two output voltages V ₀₁ ,
V ₀₂ is supplied to the subtraction amplifier circuit 12, where a predetermined calculation operation is performed, and then output as the first voltage V _t1 ,
The signal is supplied to a first analog / digital converter 7a in the controller 7. In this case, since the current flowing through the voice coil motor 6 is zero or almost zero, the first voltage V
The value of _t1 is the potential at the other end of the shunt resistor 12e, that is, the reference voltage V2 or a value very close thereto. The motor winding 1
These two output voltages V ₀₁ and V ₀₂ based on the connection point between the first resistor 11a and the first resistor 11c are equal to the motor winding 11
a, the sense resistor 11b, the first resistor 11c, and the second resistor 11d are expressed as follows using the respective resistance values described above.

V ₀₁ = {Rm / (Rm + Rs)} × Va V ₀₂ = {R1 / (R1 + R2)} × Va where Va is the voltage between one terminals of the bridge circuit 11. When obtaining the offset voltage Voff, from _{Voff = V 01 -V 02, Voff} = [{Rm / (Rm + Rs) } - {R1 / (R
1 + R2)｝] × Va, and the offset voltage Vof increases as the voltage Va increases.
f also increases.

Next, the control unit 7 presses the head support spring 5 against the stopper side of the ramp portion 5a, that is, generates a digital output having a value for shifting the head 2 to the outermost direction, and outputs a digital / analog converter 8 To supply. The digital / analog converter 8 converts this digital output into a corresponding analog voltage Vo and supplies it to the voice coil motor driver 9. The voice coil motor driver 9 sets two analog voltages such that a current corresponding to the analog voltage Vo flows through the motor winding 11a, and applies these analog voltages to the back electromotive force of the voice coil motor 6 including the motor winding 11a. The power is supplied to the power detection circuit 10. One of the set analog voltages Vo is a sense resistor 1
1b and a connection point between the second resistor 11d and the other 1b.
The two voltages are supplied to a connection point between the motor winding 11a and the first resistor 11c, and the second voltage V _t2 output from the back electromotive force detection circuit 10 (subtraction amplifier circuit 12) in the same manner as described above. Is the first analog / digital converter 7 in the controller 7
a. At this time, a current flows through the voice coil motor 6, but since the movement of the swing arm 4 is restricted, the voice coil motor 6 is not in a driving state, and both ends of the motor winding 11a Back electromotive force V
_bemf is not generated, therefore, the second voltage V _t2, does not include the impact of the back electromotive force generated by the motor windings 11a moves.

At this time, based on the supplied first and second voltages V _t1 and V _t2 , the control unit 7 determines the ratio of the change in the magnitude of the offset voltage Voff to the change in the voltages Vc and Vo, ie, The slope (offset coefficient) Koff of the offset voltage Voff is calculated.
off is expressed as follows.

Koff = (V _t2 −V _t1 ) / (Vo−Vc) The offset coefficient Koff thus obtained is calculated by the controller 7
Is stored in the circuit offset correction unit 7b, and is used for subsequent offset correction.

The operation so far relates to the operation at the time of activation of the drive circuit system of the voice coil motor. In the operation at the time of activation, the head support spring 5 is still mounted on the ramp portion 5a. Spindle motor for rotating the hard disk 1 (not shown)
Also not driven.

Subsequently, the rotation of the spindle motor is started, and the operation shifts to the normal operation of the drive circuit system of the voice coil motor. Upon receiving the command to move the magnetic head 2, the control unit 7 generates a digital output for moving the magnetic head 2 to a predetermined track on the hard disk 1 and supplies the digital output to the digital / analog converter 8. The digital / analog converter 8 converts this digital output into a corresponding analog voltage V
Is supplied to the voice coil motor driver 9 via the unit gain amplifying circuit 15 and the filter kilo 16. The voice coil motor driver 9 supplies a driving current corresponding to the analog voltage V to the voice coil motor 6, and thereby the voice coil motor 6 is driven.
By driving the voice coil motor 6, the swing arm 4 is rotated, and the head support spring 5 moves away from the ramp portion 5a and moves to the hard disk 1 side.
The magnetic head 2 starts moving toward the predetermined track.

Here, the voltage for flowing the drive current is supplied to the back electromotive force detection circuit 10 in the same manner as in the above-described calculation of the offset coefficient, and is applied between one terminals of the bridge circuit 11. At this time, since current is passed through the motor winding 11a of the voice coil motor 6 and the voice coil motor 6 is in a driving state, the voice coil motor 6 The back electromotive force V _bemf is generated, and the back electromotive force V _bemf is generated.
_bemf sequentially increases as the rotation speed of the voice coil motor 6 increases. Therefore, the bridge circuit 1
1 is the first and second voltages V ₀₁ , V ₀₁ derived between the other terminals of the bridge circuit 11 whose balance state is lost.
₀₂ is as follows based on a connection point between the motor winding 11a and the first resistor 11c.

V ₀₁ = {Rm / (Rm + Rs)} × (Vb−V _bemf ), V ₀₂ = {R1 / (R1 + R2)} × Vb where Vb is applied between one terminals of the bridge circuit 11 Voltage.

The first and second signals obtained by the bridge circuit 11
Voltage V _01, V ₀₂ of is subtracted amplified in succeeding the subtracting amplifier circuit 12, subtraction in the output of the amplifier circuit 12 includes first and second voltage V _02, V ₀₁ of the voltage difference (V ₀₂ -V ₀₁₎ corresponding to (proportional to) the output voltage V _{ou t} is derived. Since the output voltage V _out includes a back electromotive force V _bemf component that varies according to the rotation speed of the voice coil motor 6, it can be regarded as a signal representing the speed of the voice coil motor 6. The control unit 7 detects the back electromotive force V _bemf and receives it as a signal indicating the speed of the voice coil motor 6, and the first analog / digital conversion unit 7a converts the signal indicating the speed into a corresponding digital signal. And supplies it to the circuit offset correction unit 7b. Circuit offset correction unit 7
b corrects the value of this digital signal based on the offset coefficient Koff already stored, and generates a signal representing the actual speed of the voice coil motor 6.
Subsequently, the output of the circuit offset correction unit 7b is supplied to the speed correction unit 7c and the integration circuit unit 7d. Speed correction unit 7c
Calculates the difference between the speed of the voice coil motor 6 included in the output voltage V _out and the next target speed of the voice coil motor 6, performs an operation of multiplying the difference by a predetermined constant, Then, a first digital output for determining a speed at which the voice coil motor 6 is to be rotated, that is, a speed at which the magnetic head 2 is to be moved next is generated. Further, the integration circuit unit 7d integrates a deviation amount between the actual speed of the voice coil motor 6 obtained by the circuit offset correction unit 7b and the target speed, and the voice coil motor 6 applies an external force, for example, the support shaft 4a. A second digital output that is balanced with the frictional force or the like is generated. The first digital output and the second digital output are added, and further become a digital output in consideration of the digital output (actual center output value) held in the center value holding unit 7g, which is output from the control unit 7. You.

Subsequently, the digital output output from the control unit 7 is supplied to a digital / analog converter 8. Digital / analog converter 8 converts the digital output into an analog voltage V _i corresponding supplies to the voice coil motor driver 9 via a unity gain amplifier circuit 15 and the like. A voice coil motor driver 9, a voltage required to flow the driving current corresponding to the analog voltage V _i to the motor windings 11a and supplied to the voice coil motor 6, as a result, the same voltage is counter electromotive force detecting circuit 10 is also supplied. At this time, in the bridge circuit 11, the back electromotive force V _bemf generated in the motor winding 11a is similarly detected by the control unit 7 from the output voltage of the subtraction amplifier circuit 12, and
Thereafter, the above operation is repeatedly executed.

As described above, according to the present embodiment, the control unit 7
Calculates the digital output value (actual center value) from the control unit 7 at which the current flowing through the voice coil motor 6 becomes zero or very close to it when the magnetic disk drive is started, and calculates the calculated digital output value. With the voice coil motor 6 in the non-driven state, the voltage between the terminals of the motor winding 11a is measured. Based on the measured value at that time, the current flowing through the voice coil motor 6 is again zero or zero. Calculate the value of the digital output that is very close,
Using the calculated digital output value, the process of measuring the voltage between the terminals of the motor winding 11a is repeatedly executed while the voice coil motor 6 is kept in the non-driving state, and actually flows to the voice coil motor 6. The current is zero,
Alternatively, the minimum digital output value that is extremely close to zero is obtained, and the obtained digital output value is used as the actual center value of the magnetic disk device thereafter. When moving to a predetermined track, the accuracy of the search process for the data zone of the hard disk 1 and the accuracy of the center value at the time of seeking, etc., are significantly increased regardless of the variation in the components and circuit components constituting the magnetic disk device. be able to.

[0043] In this case, the control unit 7 detects the counter electromotive force V _bemf generated in the motor windings 11a of the voice coil motor 6, the rotation speed of the voice coil motor 6 counter electromotive force V _bemf detected here Since it is used as information (ie, the transition speed information of the magnetic head 2), a digital output for setting the next rotation speed of the voice coil motor 6 (ie, the transition speed of the magnetic head 2) is generated. When the magnetic head 2 is moved onto a predetermined track of the hard disk 1, the control unit 7 can sequentially control and manage the moving speed of the magnetic head 2, so that the moving speed of the magnetic head 2 is constantly changed. An appropriate speed can be selected.

[0044]

According to the present invention, the control unit 7 controls the magnetic
When the disk drive is started, the electric current flowing through the voice coil motor 6 is
Digital so that flow is ideally at or near zero
The output is supplied to the digital / analog converter 8, at which time
To the voice coil motor driver 9
Voice coil motor generated by the current supplied to the
The voltage between terminals of the motor 6 (motor winding 11a) is measured.
The digital output is converted based on the measured value at
Digital output to digital / analog converter 8
Similarly, the motor coil 11a of the voice coil motor 6
Repeat the process of measuring the resulting terminal-to-terminal voltage.
The current actually flowing through the voice coil motor 6 is zero
Or a digital output that is very close to zero
The digital output value obtained here is
As the actual center value of the disk drive
Therefore, the magnetic head 2 is moved to a predetermined position on the magnetic disk 1.
When moving on the track, the value of the above digital output
Can be used as the actual center value.
Of the components and circuit components that make up the disk drive
Regardless of the crack, the data zone of the magnetic disk 1
Search processing accuracy and the center value during seek, etc.
There is an effect that it can be significantly increased .

In this case, the control unit 7 controls the voice coil mode.
The back electromotive force V _bemf generated in the motor winding 11a of the motor 6 is detected.
And outputs the detected back electromotive force V _bemf to the voice _coil model.
Information on the rotation speed of the magnetic head 6 (that is, the transition speed of the magnetic head 2).
Information), the rotation speed of the next voice coil motor 6
For setting the degree (ie, the transition speed of the magnetic head 2).
Because a digital output is generated,
The disk 2 onto a predetermined track of the magnetic disk 1
When controlling, the control unit 7 sequentially controls the transition speed of the magnetic head 2.
Can be controlled, and during the transition of the magnetic head 2
In addition, the transition speed is too slow to contact the magnetic disk 1
Or the transition speed is too fast for the magnetic disk 1.
No more collisions at an angle,
The voice coil of the magnetic head 2 can be protected from damage.
I can .

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part configuration of an embodiment of a magnetic disk drive according to the present invention.

FIG. 2 is a block diagram showing an example of a configuration of a drive circuit system of a voice coil motor used in the magnetic disk device shown in FIG.

FIG. 3 is a block diagram showing a specific configuration of a part of a driving circuit system of the voice coil motor shown in FIG. 2;

FIG. 4 is a block diagram showing a specific configuration of a part of a driving circuit system of the voice coil motor shown in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hard disk (magnetic disk) 2 Magnetic head 3 Head transfer mechanism 4 Swing arm 4a Support shaft of swing arm 4 Head support spring 5a Lamp part 6 Voice coil motor (VCM) 7 Control unit (CPU) 7a First analog / digital Conversion unit (A / D) 7b Circuit offset correction unit 7c Speed correction unit 7d Integrating circuit unit 7e Second analog / digital conversion unit 7f Center value calculation unit 7g Center value holding unit 8 Digital / analog converter (D / A) Reference Signs List 9 voice coil motor (VCM) driver 10 back electromotive force detection circuit 11 bridge circuit 11a motor winding of voice coil motor 6 11b sense resistor 11c first resistor 11d second resistor 12 subtraction amplifier circuit 12a operational amplifier 12b first series Resistance 12c Second series resistance 12d Feedback Anti 12e shunt resistance 13 reference voltage generation circuit 13a first bleeder resistance 13b second bleeder resistance 14 reference voltage amplification circuit 14a operational amplifier 14b first feedback resistance 14c amplification factor setting resistance 15 unit gain amplification circuit 15a operational amplifier 16 filter circuit

Claims (1)

(57) [Claims] [1 claim: a rotating magnetic disk, a magnetic head for recording / reproducing information on the magnetic disk, and a control unit for generating a digital output to shift the magnetic head, the
A digital converter that converts the digital output of the control unit to an analog voltage
And analog / digital converters and
Drive the chair coil motor to move the magnetic head
Voice coil motor that moves in the radial direction of the air disk
A magnetic disk drive having a driver.
When the magnetic disk drive is started, the voice coil
Ideal value or zero to make the drive current flowing to the motor zero
Outputs a digital output close to its ideal value to the digital / analog
To the log converter, at which time the voice coil mode
Power supplied from the data driver to the voice coil motor.
Voltage between the terminals of the voice coil motor caused by current flow
The digital output value.
Multiple times, and based on these measured terminal voltages,
The current flowing through the voice coil motor is substantially
The value of the digital output that becomes zero is calculated, and this
Digital output value when driving the voice coil motor
A magnetic disk drive characterized in that it has an actual center output value .