JP2000113618A - Retraction circuit of magnetic disk drive and retracting method of magnetic disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the retraction circuit and retracting method of the magnetic disk drive which can obtain large electric power enough to retract a magnetic head by allowing a counter electromotive force to be larger than a motor driving voltage by performing the half-wave driving (unipolar driving) of respective phase coils of a spindle motor. SOLUTION: When the electric power is supplied, the motor driving voltage (+5 V) is supplied to the neutral point N of the spindle motor 3 through a relay contact 18b to control the conduction of respective FETs 15U to 15W and a motor driving current is supplied in the order of a U-phase coil, a V-phase coil, and a W-phase coil to rotate the spindle motor 3 at a constant speed. When the power source is off, counter electromotive forces generated by the respective phase coils of the spindle motor 3 are rectified by a full-wave rectifying circuit 16 and the rectification outputs are supplied to a magnetic head (voice coil motor) 6 through relay contacts 18c and 18d to move the magnetic head to an unloading position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retract circuit for a magnetic disk drive, and more particularly, to a voice coil motor and the like by performing full-wave rectification of a back electromotive force generated in each winding of a spindle motor for rotating a magnetic disk. The present invention relates to a magnetic disk drive retract circuit and a magnetic disk drive retract method in which a magnetic head is moved to a retracted position by supplying the magnetic head to a retract position.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 58-6560 discloses a protection circuit for converting kinetic energy of a magnetic disk rotating by inertia into electric energy when a power supply is cut off and transferring a magnetic head. Describes a magnetic disk drive in which the magnetic head is moved out of the data recording area of the magnetic disk by operating the magnetic disk drive.

FIG. 6 is a circuit diagram of a conventional magnetic disk protection circuit disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 58-6560. The conventional magnetic disk protection circuit shown in FIG. 6 includes a three-phase DC motor 101 for rotationally driving a magnetic disk (not shown) and a three-phase DC motor for full-wave rectification of the back electromotive force generated by the three-phase DC motor 101. Full-wave rectifier circuit 102
, Magnetic head positioning coil 103, power supply 104
And a relay 105, a motor drive circuit 106, and the like.
Rectification output terminals 102a, 102 of three-phase full-wave rectifier circuit 102
Between 2b, a shunt resistance (bleeder resistance) 107 and a smoothing capacitor 108 are connected, respectively, and a magnetic head positioning coil 103 is connected via an overcurrent prevention resistance (current limiting resistance) 109. I have.

When power is supplied from the power supply 104, the relay 105 operates, and the contacts 105a to 105c of the relay 105 are in the state shown by the dotted lines. Thus, each output terminal of the motor drive circuit 106 and each winding terminal of the three-phase DC motor 101 are connected to each of the contacts 105a to 105a.
5c are connected to each other through the motor drive circuit 106.
Accordingly, the three-phase DC motor 101 is driven to rotate.

When the power supply from the power supply 104 is stopped due to a power failure or the like, the operation of the relay 105 is restored, and the contacts 105a to 105c of the relay 105 are in the state shown by solid lines, and the windings of the three-phase DC motor 101 are turned off. The line terminal and each AC input terminal of the three-phase full-wave rectifier circuit 102 are connected to each
105c. As a result, the back electromotive force generated at each winding terminal of the three-phase DC motor 101 that continues to rotate due to inertia generates a three-phase full-wave rectifier circuit 102.
The DC voltage rectified by the smoothing and smoothed by the smoothing capacitor 108 is a resistor (current limiting resistor) 109 for overcurrent prevention.
To the coil 103 for positioning the magnetic head. When a current is supplied to the magnetic head positioning coil 103, the magnetic head (not shown) is moved out of the data recording area of the magnetic disk.

[0006] Japanese Patent Application Laid-Open No. 8-63920 discloses that
A load / unload device of a magnetic disk device having a mechanism for retracting a head slider to a retract area outside a disk is described.

Further, Japanese Patent Application Laid-Open No. Hei 9-245428 discloses that the time required for stopping a spindle motor (SPM) includes a disk and a head in a CSS (contact start stop) zone. Describes a magnetic disk device and a spindle motor braking method for extending the disk life by greatly shortening the contact time of the disk.

The magnetic disk device and its spindle motor braking method are configured as follows. The SPM brake circuit performs the retraction using the back electromotive force generated in all the three-phase coils during the inertial rotation of the SPM after the power is turned off. When the combined voltage of the back electromotive voltages is lower than the reference voltage, the retract is performed. It is determined that the operation has already been completed, and all three-phase coils are short-circuited to the ground to apply a strong power generation brake. As a result, the time required for stopping the SPM and the time for friction between the disk and the head in the CSS zone can be greatly reduced, and the wear of the CSS zone can be effectively suppressed to extend the life of the disk. It becomes possible.

[0009]

By the way, as the size and capacity of the magnetic disk drive become smaller, the distance between the disk and the magnetic head becomes smaller and smaller, and the value is several tens of nanometers (nm) at present. Have been. In order to reduce the distance, the disk surface must be smooth so that the magnetic head can run on the disk surface stably.

However, when the disk surface is smoothed, a conventional CSS (contact start stop) is required.
In this case, the problem that the magnetic head is attracted to the disk easily occurs. In recent years, with the spread of portable computers, the need to improve impact resistance and reliability has been added.
A load / unload method without performing SS (contact start / stop) has been adopted.
This method utilizes the power stored as the inertial energy of the spindle motor to retract the magnetic head out of the disk after the power is turned off.

A conventional magnetic disk drive employs a full-wave drive system (bipolar drive system) in which a current is applied to each phase winding (U-phase winding, V-phase winding, W-phase winding) of a spindle motor in both directions. are doing. FIG. 7 is an explanatory diagram showing voltage waveforms when the spindle motor is driven by full-wave (bipolar driving).

FIG. 7 shows a voltage waveform when the motor drive voltage is 5 volts. In the full-wave drive system (bipolar drive system), two windings are always energized to rotate the spindle motor. As shown in FIG. 7, in the section a, a current flows from the V phase to the U phase, and in the next section b, W
A current flows from the phase to the U phase, a current flows from the W phase to the V phase in the next section c, a current flows from the U phase to the V phase in the next section d, and a U phase to the W phase in the next section e. A current flows, and in the next section f, a current flows from the V phase to the W phase. Thus, the spindle motor is driven to rotate by switching the timing of the current flow and the direction of the current in each phase winding in a predetermined order.

In the full-wave drive system (bipolar drive system), a spindle motor is driven by applying a motor drive voltage (for example, 5 volts) to two windings. The peak-to-peak value must be less than or equal to the motor drive voltage (eg, 5 volts). This is because the peak-to-peak value of the back electromotive force generated between the two windings is equal to the motor drive voltage (for example, 5 volts).
Is exceeded, the motor drive power cannot be supplied to the respective windings of the spindle motor from the motor drive power supply side, and the rotation of the motor cannot be normally controlled.

For this reason, in a conventional magnetic disk drive using the full-wave drive system (bipolar drive system), the back electromotive voltage p generated by the spindle motor after the power is turned off.
The -p value (peak-to-peak value) is equal to or lower than the motor drive voltage (for example, 5 volts), and the magnetic head is retracted using this back electromotive force.

However, in a small magnetic disk drive (disk diameter of, for example, 1.8 inches or less), the inertia energy is small because the diameter of the disk is small. For this reason, the back electromotive force that can be taken out from the spindle motor also becomes small, and sufficient power for retracting the magnetic head cannot be obtained. In particular, in the load / unload system in which the magnetic head is retracted to an unload position provided outside the disk, the magnetic head is moved to the CSS on the disk.
More power is often required for systems that move to the (contact start stop) area. For this reason, if the back electromotive force that can be taken out from the spindle motor is small, the magnetic head may not be able to be reliably retracted to the unload position.

[0016]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. By driving each phase winding of a spindle motor by a half-wave drive (unipolar drive), the back electromotive voltage is higher than the motor drive voltage. To be able to tolerate
It is an object of the present invention to provide a magnetic disk drive retract circuit and a magnetic disk drive retract method that can provide sufficient power to retract a magnetic head.

[0017]

According to a first aspect of the present invention, there is provided a retract circuit for a magnetic disk drive and a retract method for a magnetic disk drive, wherein a spindle motor for rotating a magnetic disk and a spindle motor are provided. A motor drive circuit that rotates by half-wave drive, a full-wave rectifier circuit that full-wave rectifies the back electromotive force of the spindle motor, and a magnetic head drive unit that moves the magnetic head in the radial direction of the magnetic disk. The rectified output of the circuit is supplied to a magnetic head drive unit. Thus, the magnetic head can be retracted to the magnetic head retract position.

Therefore, in the magnetic disk drive retract circuit and the magnetic disk drive retracting method according to the first and seventh aspects, the spindle motor is driven by half-wave driving. A back electromotive voltage higher than the voltage can be allowed to occur. For example, when the motor drive voltage is 5 volts, the pp value of the back electromotive force has to be 5 volts or less in the conventional full-wave drive system, whereas the back electromotive voltage of the half wave drive system has to be 5 volts or less. What is necessary is just to make 0-p value 5 volts or less. Therefore, the retract circuit of the magnetic disk drive and the retract method of the magnetic disk drive according to claims 1 and 7 can take out about twice the back electromotive force as compared with the conventional full-wave drive system. As described above, a larger back electromotive force can be taken out than in the related art. Therefore, by driving the magnetic head driving unit based on the back electromotive force, the magnetic head can be reliably retracted to the magnetic head retracted position.

In the retract circuit of the magnetic disk drive according to the second aspect, the spindle motor includes a star-connected three-phase winding, and a switch means that conducts a neutral point of the three-phase winding when the motor is driven. , And each of the three-phase windings is connected to the other end of the power supply via a respective power semiconductor switching element.

As described above, the retract circuit of the magnetic disk drive according to the second aspect of the present invention provides
Since the neutral point of the phase winding is connected to one end of the power supply via switch means, and each winding of the three-phase winding is connected to the other end of the power supply via each power semiconductor switching element, When driving the motor, the spindle motor can be rotationally driven by switching the windings to be energized in a predetermined order at a predetermined timing while supplying a current to each of the three-phase windings in one direction.

According to a third aspect of the present invention, in the retract circuit of the magnetic disk drive, the spindle motor is connected in a star-type connection.
A neutral point of the three-phase winding is connected to the positive electrode of the power supply via a switch that becomes conductive when the motor is driven, and each winding of the three-phase winding is a power semiconductor switching element. And the three-phase windings are connected to the AC input terminals of the full-wave rectifier circuit, respectively, and are connected between the positive output terminal of the full-wave rectifier circuit and the positive terminal of the power supply. And a constant voltage diode is connected to the switch.

Therefore, in the retract circuit of the magnetic disk drive according to the third aspect, the flyback voltage generated at the time of switching the energization of each winding of the spindle motor is changed via the diode constituting the full-wave rectifier circuit and the constant voltage diode. It can be absorbed by the power supply. Since the diodes constituting the full-wave rectifier circuit are also used for flyback voltage absorption, circuit components can be reduced.

According to a fourth aspect of the present invention, there is provided a retract circuit for a magnetic disk drive, wherein the switching means is in a non-conductive state between the rectification output terminal of the full-wave rectifier circuit and the magnetic head driving part when the motor is driven and is in a conductive state when the motor is not driven. Characterized by being interposed.

As described above, the retract circuit of the magnetic disk drive according to the fourth aspect of the present invention is configured to cut off the connection between the rectification output terminal of the full-wave rectifier circuit and the magnetic head driving unit when the motor is driven. The generated back electromotive force is not supplied to the magnetic head driving unit. Therefore, it is possible to completely prevent the back electromotive force from being supplied to the magnetic head driving unit when the motor is driven and the magnetic head from moving to an undesired position. The switching means supplies the rectified output of the full-wave rectifier circuit to the magnetic head driving unit when the power supply to the motor is stopped, so that the magnetic head can be reliably retracted to the magnetic head retract position.

According to a fifth aspect of the present invention, in the retract circuit of the magnetic disk drive, the spindle motor is connected in a star-type connection.
The three-phase windings are connected to the AC input terminals of the full-wave rectifier circuit, respectively, and the non-conduction between the rectification output terminal of the full-wave rectifier circuit and the magnetic head drive unit is performed when the motor is driven. A switching means which is in a conductive state when the motor is not driven is provided.

As described above, in the retract circuit of the magnetic disk drive according to the fifth aspect, since the switching means is provided between the rectification output side of the full-wave rectification circuit and the magnetic head driving unit, the three-phase winding is provided. The number of switching means can be reduced as compared with a configuration in which switching means which is non-conductive when the motor is driven and which is conductive when the motor is not driven are interposed between each input terminal of the full-wave rectifier circuit and the motor. Therefore, the circuit configuration can be simplified.

In the magnetic disk drive according to the present invention, the retract circuit constitutes a magnetic head drive section using a voice coil motor, and the voice coil motor drive circuit for driving the voice coil motor drives the voice coil motor. It is characterized in that the output of the voice coil motor drive circuit has a high impedance in a state where there is no voice coil motor.

As described above, the retract circuit of the magnetic disk drive according to the present invention comprises a magnetic head drive section using a voice coil motor, and the voice coil motor drive circuit for driving the voice coil motor is a voice coil motor. When the voice coil motor is not driven, a switch circuit or the like that is in a non-conductive state when the voice coil motor is not driven is provided between the voice coil motor drive circuit and the voice coil motor because the output impedance is increased when the voice coil motor is not driven. Even without this, a rectified output obtained by full-wave rectification of the back electromotive voltage of the spindle motor can be effectively supplied to the voice coil motor.

[0029]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is an explanatory view showing the structure of a magnetic disk drive provided with a retract circuit according to the present invention. The magnetic disk drive 1 includes a spindle motor 3 on which a magnetic disk 2 for data recording is mounted, a carriage arm 5 on which a magnetic head 4 is mounted, and a magnetic head 4 having a diameter substantially equal to the diameter of the magnetic disk 2 via the carriage arm 5. Head driving unit 6 for moving the magnetic head unit 4 in the direction
And a load / unload mechanism 7 for retracting the outside of the magnetic disk 2. Spindle motor 3 is 3
It is configured using a phase DC motor (DC motor).
The magnetic head drive unit 6 is configured using a voice coil motor.

FIG. 1 is a circuit diagram of a retract circuit of a magnetic disk drive according to the present invention. The retract circuit includes a CPU section 11, a D / A conversion section 12, a spindle motor drive circuit 13, a voice coil motor drive circuit (magnetic head drive circuit) 14, and three N-channel enhancement type field effect transistors (NMOS FEs).
T) 15U, 15V, 15W, full-wave rectifier circuit 16,
It comprises a constant voltage diode 17, a relay consisting of an exciting winding 18a and relay contacts 18b, 18c, 18d, a power supply unit 19, a spindle motor 3, and a magnetic head drive unit (voice coil motor) 6.

The relay contact 18b corresponds to the switch means which is turned on when the motor is driven as described in the claims. Note that the switch unit that becomes conductive when the motor is driven may be configured using a semiconductor switching element such as a field-effect transistor, for example. The relay contact 18c and the relay contact 18d correspond to the switch means which is turned on when the motor is not driven, as described in the claims. Note that the switch that is turned on when the motor is not driven may be configured using a semiconductor switching element such as a field effect transistor.

The spindle motor 3 is constituted by using a three-phase DC motor (DC motor). In the present embodiment, the spindle motor 3 has a three-phase winding of a star type (Y
Type) The one that is connected is used. The spindle motor 3 includes connection terminals U, V, and W for each phase winding and a connection terminal N at a neutral point.

The magnetic head driving section 6 is constituted by using a voice coil motor. The magnetic head drive unit 6 includes a terminal 6
a when a current is supplied to the terminal 6b from the magnetic head 4
Is moved from the unload position toward the center of the magnetic disk 2, and when a current is supplied from the terminal 6b to the terminal 6a, the magnetic head 4 is moved in the direction toward the unload position. When a current of a predetermined value or more is continuously supplied from the terminal 6b to the terminal 6a for a predetermined time, the magnetic head 4 is moved to an unload position (magnetic head retreat position) indicated by a dotted line in FIG.

The CPU section 11 controls the rotation speed of the spindle motor 3 and controls the positioning of the magnetic head 4. The CPU unit 11 calculates the number of rotations (rotation speed) of the spindle motor 3 per unit time based on the rotation position detection information 13a supplied from the spindle motor drive unit 13, and the number of rotations of the spindle motor 3 is set in advance. The speed command data 11a is output so that the number of rotations becomes equal to the number of rotations. Also,
The CPU unit 11 obtains a voice coil motor current value required to move the magnetic head 4 to a desired track position based on an access request such as read / write (not shown), and corresponds to the voice coil motor current value. The current data 11b is output. The speed command data 11a and the current data 11b output from the CPU 11
/ A conversion unit 12.

[0036] The D / A converter 12 is provided with the speed command data 11.
A speed command voltage signal 12a is generated and output based on a. The speed command voltage signal 12a corresponding to the speed command data 11a is supplied to the spindle motor drive circuit 13.
The D / A converter 12 generates and outputs a current command voltage signal 12b based on the current data 11b. Current data 1
The current command voltage signal 12b corresponding to 1b is supplied to the voice coil motor drive circuit 14.

The spindle motor drive circuit 13 determines that a voltage equal to or higher than a predetermined voltage is supplied to the neutral point N of the spindle motor 3 based on the voltage supplied to the neutral point voltage detection terminal 13b. Upon detection,
When detecting that a predetermined voltage (for example, +5 volts) is supplied from the power supply unit 19, the switching operation of each of the field effect transistors 15U, 15V, and 15W is controlled to operate the spindle motor 3.

Each field effect transistor 15U, 15V,
15W corresponds to the power semiconductor switching element described in the claims. The field-effect transistor 15U drives the U-phase winding of the spindle motor 3, and the drain of the field-effect transistor 15U is connected to the connection terminal U of the U-phase winding. The field-effect transistor 15V drives the V-phase winding of the spindle motor 3, and the drain of the field-effect transistor 15V is connected to the connection terminal V of the V-phase winding. The field-effect transistor 15W is for driving the W-phase winding of the spindle motor 3, and the field-effect transistor 15W
The drain of W is connected to the connection terminal W of the W-phase winding. The sources of the field effect transistors 15U, 15V, 15W are connected to the ground, respectively.

The terminal voltages of the connection terminals U, V, and W of each phase winding of the spindle motor 3
3 are supplied to the respective phase voltage detection terminals 13c, 13d, 13e. The input impedance of each of the neutral point voltage detection terminal 13b, the U-phase voltage detection terminal 13c, the V-phase voltage detection terminal 13d, and the W-phase voltage detection terminal 13b is set sufficiently higher than the impedance of each phase winding. That is, the voltage of each phase can be detected without affecting the driving power of the spindle motor 3.

The spindle motor drive circuit 13 detects the rotation position of the rotor of the spindle motor 3 based on the voltage of each phase winding supplied to each phase voltage detection terminal 13c, 13d, 13e, and detects the detected rotation of the rotor. The energization timing of each phase winding is determined based on the position, and the energization duty is determined based on the speed command voltage signal 12a.
The spindle motor drive circuit 13 supplies gate power to the gates of the respective field effect transistors 15U, 15V, 15W based on the determined energization timing and energization duty, and controls the respective field effect transistors 15U, 15V,
The switching drive of 15 W controls the energization timing of each phase winding and the amount of current supplied to each phase winding.

When a DC power supply of, for example, +5 volts is supplied from the power supply unit 19, and the excitation winding 18a of the relay is supplied by the DC power supply, the contact 18b of the relay is turned on as indicated by a dotted line. Become. In this state, the spindle motor drive circuit 13 drives the spindle motor 3 by half-wave drive (unipolar drive). The half-wave drive (unipolar drive) supplies current to one winding of the spindle motor 3 in one direction.

FIG. 3 is an explanatory diagram showing voltage waveforms when the spindle motor is driven by half-wave driving (unipolar driving).
In the section A shown in FIG. 3, only the field-effect transistor 15U corresponding to the U-phase winding is controlled to be in a conductive state, and only the U-phase winding of the spindle motor 19 is in a conductive state.
In this state, in the circuit configuration diagram shown in FIG. 2, the positive side output (+5 V) of the power supply 19, the relay contact 18b, the neutral point connection terminal N of the spindle motor 19, the U-phase winding of the spindle motor 19, the winding of the spindle motor 19 A current is supplied to the U-phase winding via a U-phase winding connection terminal U-field-effect transistor 15U-ground path. As shown in FIG.
Now, the field-effect transistor 15V corresponding to the V-phase winding
Is controlled to a conductive state, and the V
Only the phase winding becomes conductive. In this state, the positive output (+5 V) of the power supply 19, the relay contact 18b, the neutral point connection terminal N of the spindle motor 19, the V-phase winding of the spindle motor 19, the V-phase winding connection terminal of the spindle motor 19 V-electric field A current is supplied to the V-phase winding through a path of the effect transistor 15V-ground. Further, in the next section C, only the field-effect transistor 15W corresponding to the W-phase winding is controlled to be in a conductive state, and only the W-phase winding of the spindle motor 19 is in a conductive state. In this state, the positive output (+5 V) of the power source 19, the relay contact 18b, the neutral point connection terminal N of the spindle motor 19, the W-phase winding of the spindle motor 19, the W-phase winding connection terminal of the spindle motor 19, and the electric field A current is supplied to the W-phase winding through the path of the effect transistor 15W-ground.

The spindle motor drive circuit 13 rotates the spindle motor 3 by sequentially switching the phases to be energized in this manner in a predetermined order. The timing of this switching is determined by a comparator (not shown) provided inside the spindle motor drive circuit 13 by each winding connection terminal U,
It is determined by comparing the voltage waveforms of V and W with the voltage waveform of the neutral point connection terminal N, respectively, and is performed by controlling the gate signals of the field effect transistors 15U, 15V and 15W based on the comparison result. .

In the half-wave drive (unipolar drive), between the neutral point N supplied with +5 volt power and the winding connection terminals U, V, W of each phase (at both ends of each phase winding). Since driving is performed by applying a voltage of 5 volts at the maximum, the 0-p value (zero toe peak value) of the back electromotive force generated in each phase winding may be set to 5 volts or less. For this reason, the peak-to-peak value of the back electromotive voltage generated in each phase winding can be allowed up to a maximum of 10 volts, and the back electromotive force in the conventional full-wave drive (bipolar drive) can be obtained. A back electromotive voltage that is twice the voltage can be allowed. Then, this large back electromotive voltage is applied to the full-wave rectifier circuit 1.
6 and the rectified output is supplied to each relay contact 18c, 1
Magnetic head drive unit (voice coil motor) via 8d
6, the magnetic head 4 can be reliably moved to the unload position outside the magnetic disk 2.

The voice coil motor driving circuit 14
When the power is not supplied from the power supply unit 19, the output terminals 14a, 14a of the voice coil motor drive circuit 14
The impedance of b is configured to be sufficiently higher than the impedance of the voice coil motor 6. Thereby, each output terminal 1 of the voice coil motor drive circuit 14
The rectified output of the full-wave rectifier circuit 16 can be applied to the voice coil motor drive circuit without interposing a switch between the voice coil motor 6 and the voice coil motor 6 in a non-conductive state when power is not supplied. The rectified output of the full-wave rectification circuit 16 is effectively supplied to the voice coil motor 6 without being supplied to the 14 side. A switch may be provided between each of the output terminals 14a and 14b of the voice coil motor drive circuit 14 and the voice coil motor 6 so as to be in a non-conductive state when power is not supplied.

FIG. 4 is a flowchart showing the operation when the power is turned on to the magnetic disk drive. When the power is supplied to the magnetic disk device 1, the CPU unit 11 and the spindle motor drive circuit 13 start rotation of the spindle motor 3 by half-wave drive (unipolar drive) (step S1). In step S2, the CPU 11
Calculates the rotation speed of the spindle motor 3 based on the rotation position information 13a supplied from the spindle motor drive circuit 13 and confirms that the rotation speed of the spindle motor 3 has increased to a predetermined rotation speed (steady rotation). Confirmation). When it is confirmed in step S2 that the spindle motor 3 has reached the steady rotation, in step S3, the CPU 11
The magnetic head 4 at the unload position on the load / unload mechanism 7 shown in FIG. 1 is moved onto the surface of the magnetic disk 3 (load operation).

This load operation is controlled by current data (current command value) 11b output from the CPU 11.
Specifically, the current data (current command value) 11 b output from the CPU 11 is converted into a current command voltage signal (analog signal) 12 b by the D / A converter 12 and supplied to the voice coil motor drive circuit 14. . The voice coil motor drive circuit 14 receives the current command voltage signal (analog signal) 1
A voice coil motor drive current proportional to 2b is supplied to a voice coil motor which is the magnetic head drive unit 6. The voice coil motor 6 drives the carriage arm 5 to which the magnetic head 2 is attached, and moves the magnetic head 2 over the surface of the magnetic disk 2. After the magnetic head 2 is moved onto the surface of the magnetic disk 2, the servo information recorded on the surface of the magnetic disk 2 can be read via the magnetic head 2. The accurate positioning of the magnetic head 2 is performed based on the servo information obtained (step S4). By performing the calibration of each parameter in step S4, a read / write (read / write) operation can be performed, and a ready state in which a command can be received is obtained.

Here, as shown in FIG. 1, the full-wave rectifier circuit 16 comprises six rectifier diodes D1 to D6 connected in a three-phase bridge. The AC input terminals 16U, 16V, 16W of the full-wave rectifier circuit 16 are connected to winding connection terminals U, V, W of each phase of the spindle motor 3, respectively.
The positive output terminal 16P of the full-wave rectifier circuit 16 is connected to the other terminal 6b of the magnetic head drive unit (voice coil motor) 6 via a relay contact 18c. The negative output terminal 16N of the full-wave rectifier circuit 16 is connected to one terminal 6a of the magnetic head drive unit (voice coil motor) 6 via a relay contact 18d. A constant voltage diode 17 is provided between the positive output terminal 16P of the full-wave rectifier circuit 16 and the positive terminal + 5V of the power supply unit 19. The constant voltage diode 17 is for absorbing flyback generated when switching a winding to be energized. For example, U
The flyback voltage generated in the phase winding is absorbed by the power supply via the rectifying diode D5 and the constant voltage diode 17. Similarly, the flyback voltage generated in the V-phase winding and the W-phase winding is absorbed by the power supply via the rectifying diodes D3 and D1 and the constant voltage diode 17.

FIG. 5 is a flowchart showing the operation when the power of the magnetic disk drive is turned off. When the supply of power is cut off, the magnetic disk device 1 according to the present invention uses the power stored as the inertial energy of the spindle motor 3 to retract the magnetic head 4 to the unload position. Specifically, the back electromotive force generated in each phase winding of the spindle motor 3 is full-wave rectified by the full-wave rectification circuit 16 and is taken out as a DC voltage (step S).
11).

When the power supply is cut off, the operation of the relay is restored, and the relay contacts 18c and 18d are turned on as shown by solid lines in FIG. For this reason, the DC output voltage of the full-wave rectifier circuit 16 is supplied to the voice coil motor constituting the magnetic head driving unit 6 via the relay contacts 18c and 18d. Thus, the voice coil motor 6 is driven based on the back electromotive voltage generated in each phase winding of the spindle motor 3, and the magnetic head 4 is moved to the unload position (step S12). Since the output terminals 14a and 14b of the voice coil motor drive circuit 14 are in a high impedance state when the power supply is cut off,
The DC output voltage of the full-wave rectifier circuit 16 is supplied only to the voice coil motor 6. Therefore, the voice coil motor drive circuit 14 does not affect the retraction operation, and the magnetic head 4 can be reliably moved to the unload position.

After the unloading operation of the magnetic head 4 is completed, the inertial force of the spindle motor 3 is no longer necessary. Therefore, all the field effect transistors 15U, 15V and 15W are controlled to be in a conductive state, and each phase winding is controlled. By short-circuiting the terminals U, V, and W to ground, a power generation brake (dynamic brake) is applied to the spindle motor 3 (step S13), and the rotation of the spindle motor 3 is rapidly stopped. When the rotation of the spindle motor 3 stops (step S14), the processing at the time of power off is completed.

When the spindle motor drive circuit 13 detects that the power supply is cut off based on the voltage supplied to the neutral point voltage detection terminal 13b being equal to or less than a predetermined value, the spindle motor drive circuit 13 starts from the time of the power supply cut off. When a preset head retract time has elapsed, all the field effect transistors 15U, 15V, and 15W are controlled to be in a conductive state, and a power generation brake (dynamic brake) is applied. It should be noted that, without providing a timer circuit or the like for measuring the head retraction time, when the rotation speed of the spindle motor 3 becomes equal to or less than a predetermined rotation speed, or a counter electromotive force generated in each phase winding of the spindle motor 3 is generated. When the voltage becomes equal to or lower than a preset voltage, a power generation brake (dynamic brake) may be applied.

In the magnetic disk device 1, when the power is turned off, the magnetic head 4 must be promptly moved to the unload position. This is because the rotation speed of the spindle motor 3 decreases with time, and the back electromotive voltage decreases in proportion to the rotation speed. If the back electromotive voltage is insufficient and the magnetic head 4 cannot be moved to the unload position, the magnetic head 4 will land on the surface of the magnetic disk 2.

In this case, the magnetic head 4 is attracted to the mirror-finished and very smooth disk surface, and the spindle motor 3 may not be able to rotate even when the power is turned on. Even if the magnetic head 4 is in contact with the surface of the magnetic disk 2 and an external impact is applied to the magnetic disk device 1, even if the magnetic head 4 is in contact with the surface of the magnetic disk 2, the magnetic head 4 damages the disk surface and magnetic recording is performed. It is possible to destroy the data that is stored.

In the retract circuit and the retract method of the magnetic disk drive according to the present invention, the driving method of the spindle motor 3 is changed from the conventional full-wave drive (bipolar drive) to half-wave drive (unipolar drive). In the full-wave drive, since the drive is performed by applying a maximum voltage of 5 volts between two windings of the spindle motor 3, the peak-to-peak value of the back electromotive force must be 5 volts or less. In the half-wave driving, since a voltage of a maximum of 5 volts is applied between the neutral point connected to the power supply of 5 volts and the winding, the 0-p value of the back electromotive voltage may be set to 5 volts or less.

Therefore, by employing the half-wave driving method, it is possible to obtain a back electromotive voltage which is almost twice as large as that of the conventional full-wave driving method. Then, since the back electromotive voltage higher than the conventional one is full-wave rectified and supplied to the voice coil motor 6, the force generated at the time of the retract operation can be approximately doubled.

As described above, the retract circuit and the retract method of the magnetic disk drive according to the present invention can supply sufficient electric power to the voice coil motor 6 constituting the magnetic head drive unit 6, so that the magnetic head 4 It can be moved to the unload position at high speed (for a short time) and reliably. Therefore, there is a problem that the magnetic head 4 lands on the surface of the magnetic disk 2 due to insufficient back electromotive voltage, and the magnetic head 4 damages the surface of the magnetic disk 2 due to an external impact even if the magnetic head 4 is not sucked. The problem of destroying data can be avoided, and a more reliable magnetic disk device 1 can be provided.

In FIG. 1, power of +5 volts is supplied to the neutral point N of the spindle motor 3, and the windings U,
Field effect transistor 15 between V, W and ground
Although the circuit configuration in which the U, 15V, and 15W are provided is shown, the neutral point N of the spindle motor 3 is connected to the ground, and +5 volts is applied to each phase winding U, V, and W via the field effect transistor. The spindle motor 3 may be operated by supplying power in a predetermined order.

Although FIG. 1 shows an example in which the connection of the spindle motor 3 is a star connection (Y connection), the spindle motor 3 may have a delta connection. Even in the case of the delta connection, a half-wave drive method in which a current flows in only one of the phase windings in one direction can allow a 0-p value of the back electromotive voltage to a motor drive voltage (for example, 5 volts). .
Therefore, a back electromotive force approximately twice that of the conventional half-wave driving method can be taken out, and the magnetic head can be moved to the magnetic head retreat position in a short time and reliably based on the back electromotive force.

[0060]

As described above, the retract circuit of the magnetic disk drive and the retract method of the magnetic disk drive according to the first and seventh aspects have a configuration in which the spindle motor is driven by half-wave. The generation of a back electromotive voltage higher than the motor drive voltage on the line can be tolerated. For example, when the motor driving voltage is 5 volts, the back electromotive force peak-to-peak in the conventional full-wave driving method is used.
The value had to be less than 5 volts,
In the half-wave driving method, the 0-p value of the back electromotive voltage may be set to 5 volts or less. Therefore, the retract circuit of the magnetic disk drive and the retract method of the magnetic disk drive according to claims 1 and 7 can take out about twice the back electromotive force as compared with the conventional full-wave drive system. As described above, since a larger back electromotive force can be taken out than in the related art, by driving the magnetic head driving unit based on the back electromotive force,
The magnetic head can be reliably retracted to the magnetic head retracted position.

According to a second aspect of the present invention, in the retract circuit of the magnetic disk drive, the neutral point of the three-phase winding is connected to one end of the power supply via the switch means when the motor is driven. Since it is configured to be connected to the other end of the power supply via the power semiconductor switching element, when the motor is driven, current is supplied to each of the three-phase windings in one direction, and the winding to be energized is driven at a predetermined timing. By switching in a predetermined order, the spindle motor can be driven to rotate.

According to a third aspect of the present invention, a retract circuit for a magnetic disk drive absorbs a flyback voltage generated at the time of switching of energization to each winding of a spindle motor to a power supply via a diode constituting a full-wave rectifier circuit and a constant voltage diode. Can be done. Since the diodes constituting the full-wave rectifier circuit are also used for flyback voltage absorption, circuit components can be reduced.

The retract circuit of the magnetic disk drive according to the fourth aspect of the present invention is configured to cut off the connection between the rectification output terminal of the full-wave rectifier circuit and the magnetic head drive unit when the motor is driven. No power is supplied to the magnetic head drive. Therefore, it is possible to completely prevent the back electromotive force from being supplied to the magnetic head driving unit when the motor is driven and the magnetic head from moving to an undesired position. The switching means supplies the rectified output of the full-wave rectifier circuit to the magnetic head driving unit when the power supply to the motor is stopped, so that the magnetic head can be reliably retracted to the magnetic head retract position.

In the retract circuit of the magnetic disk drive according to the fifth aspect, the switching means is interposed between the rectification output side of the full-wave rectifier circuit and the magnetic head driving section. The number of switching means can be reduced as compared with a configuration in which switching means which is non-conductive when the motor is driven and which is conductive when the motor is not driven are interposed between the respective input terminals. Therefore, the circuit configuration can be simplified.

In the magnetic disk drive according to the present invention, the retract circuit constitutes a magnetic head drive section using a voice coil motor, and the voice coil motor drive circuit for driving the voice coil motor drives the voice coil motor. Since the output impedance is increased in the absence state, there is no need to provide a switch circuit or the like between the voice coil motor drive circuit and the voice coil motor which is turned off when the voice coil motor is not driven. A rectified output obtained by full-wave rectification of the back electromotive voltage of the spindle motor can be effectively supplied to the voice coil motor.

Since the retract circuit and the retract method of the magnetic disk drive according to the present invention can supply sufficient electric power to the magnetic head driving section, the magnetic head can be moved to the unload position at high speed (for a short time) and reliably. Can be moved. Therefore, there is a problem that the magnetic head lands on the magnetic disk surface due to insufficient back electromotive voltage and is attracted, and even if the magnetic head is not attracted, the magnetic head damages the magnetic disk surface due to an external impact and destroys data. It is possible to avoid the problem that the magnetic disk device is more reliable.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a retract circuit of a magnetic disk drive according to the present invention.

FIG. 2 is an explanatory diagram showing the structure of a magnetic disk drive provided with a retract circuit according to the present invention.

FIG. 3 is an explanatory diagram showing voltage waveforms when a spindle motor is driven by half-wave driving (unipolar driving).

FIG. 4 is a flowchart illustrating an operation when power is supplied to the magnetic disk device.

FIG. 5 is a flowchart showing an operation when the power of the magnetic disk device is turned off.

FIG. 6 is a circuit configuration diagram of a conventional magnetic disk protection circuit.

FIG. 7 is an explanatory diagram showing voltage waveforms when the spindle motor is driven by full-wave (bipolar driving).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnetic disk drive 2 Magnetic disk 3 Spindle motor 4 Magnetic head 5 Carriage arm 6 Magnetic head drive part (voice coil motor) 7 Load / unload mechanism 13 Spindle motor drive circuit 14 Voice coil motor drive circuit 15U, 15V, 15W Power semiconductor Switching element (field effect transistor) 16 Full-wave rectifier circuit 17 Constant voltage diode 18b, 18c, 18d Switch means (relay contact)

Claims (7)

[Claims] 1. A spindle motor for rotating a magnetic disk, a motor driving circuit for rotating the spindle motor by half-wave driving, a full-wave rectifying circuit for full-wave rectifying a back electromotive voltage of the spindle motor, A magnetic head drive unit for moving a magnetic head in a radial direction of the magnetic disk, wherein a rectified output of the full-wave rectifier circuit is supplied to the magnetic head drive unit. circuit. 2. The spindle motor includes a star-connected three-phase winding, and a neutral point of the three-phase winding is connected to one end of a power supply through a switch that turns on when the motor is driven. 2. The retract circuit according to claim 1, wherein each of the three-phase windings is connected to the other end of the power supply via a power semiconductor switching element. 3. The spindle motor includes a star-connected three-phase winding, and a neutral point of the three-phase winding is connected to a positive terminal of a power supply through a switch that becomes conductive when the motor is driven. , Each winding of the three-phase winding is connected to the negative electrode side of the power supply via each power semiconductor switching element, and each winding of the three-phase winding is connected to each AC input terminal of the full-wave rectifier circuit. A constant voltage diode is connected between the positive output terminal of the full-wave rectifier circuit and the positive terminal of the power supply, and the flyback voltage generated at the time of energization switching for each of the three-phase windings is connected to the full-wave rectifier circuit. 2. A structure in which the power source absorbs the power through a diode constituting a wave rectifier circuit and the constant voltage diode.
A retract circuit of the magnetic disk drive according to the above. 4. A switching means interposed between a rectification output terminal of the full-wave rectifier circuit and the magnetic head driving unit, the switching unit being non-conductive when the motor is driven and being conductive when the motor is not driven. A retract circuit for a magnetic disk drive according to claim 1. 5. The full-wave rectifier circuit according to claim 5, wherein the spindle motor includes a star-connected three-phase winding, and each of the three-phase windings is connected to each AC input terminal of the full-wave rectifier circuit. 2. A retractable magnetic disk drive according to claim 1, wherein a switching means which is non-conductive when the motor is driven and which is conductive when the motor is not driven is provided between the rectified output terminal of the magnetic disk drive and the magnetic head drive unit. circuit. 6. The voice coil motor driving circuit for driving the voice coil motor, wherein the magnetic head driving unit is configured using a voice coil motor, and the voice coil motor driving circuit is driven when the voice coil motor is not driven. 2. The retract circuit according to claim 1, wherein the output of the magnetic disk drive is configured to have a high impedance. 7. A half-wave drive of a spindle motor that rotationally drives a magnetic disk, so that a back electromotive voltage of the spindle motor can be allowed to be higher than a drive voltage of the spindle motor. A retracting method for a magnetic disk drive, wherein a magnetic head is retracted to a magnetic head retracting position by supplying a rectified output obtained by full-wave rectification of an electromotive voltage to a magnetic head driving unit.