JPH0564473A - Magnetic disc drive - Google Patents

Abstract

PURPOSE:To reduce bit cost by constituting a magnetic disc drive of a power supply section, a motor driving current control section, a power supply selecting section, a motor driving circuit section, and a head disc assembly(HDA). CONSTITUTION:Upon turn ON of power supply 1 for a magnetic disc unit, a controller 6 selects an HDA 5 for starting a spindle and a power supply selecting section 3 selects a power supply 1 for the HDA 5 and feeds power through a drive current control section 2 to a motor driving circuit section 4. A drive current control section 2 performs driving optimal for start/stop of contact and upon finish of starting, the power supply selecting section 3 selects a driving current control section 2 for an HDA 5 to be started next. Consequently, a spindle motor 5a is started optimally through the HDA 5 and the spindle in a magnetic disc unit is started without causing damage on a magnetic head or a magnetic disc. According to the invention, bit cost can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device having a plurality of head disk assemblies (hereinafter abbreviated as HDA) mounted in a housing of the device.

[0002]

2. Description of the Related Art In a conventional magnetic disk device, a power supply, a motor drive circuit, and a motor have a one-to-one relationship, and controlling a drive current at start-up requires a very heavy load on a transistor of the control circuit. In the control transistor, the heat generation amount = control current × (power supply voltage−motor back electromotive force−
(Motor coil impedance × control current), and the load on the drive circuit unit becomes extremely large at the time of startup. Therefore, the startup characteristics are often limited by the restrictions on the circuit side rather than the optimum startup characteristics.

Further, in a magnetic disk device in which a plurality of HDAs are mounted in the magnetic disk device, the mounting volume of the drive circuit and the cost are increased.

Therefore, in the conventional magnetic disk, a series resistor is often inserted between the motor coil and the drive circuit at the time of starting to limit the starting current, or the starting current is reduced to reduce the circuit load.

[0005]

SUMMARY OF THE INVENTION In the above-mentioned prior art,
At the time of starting the rotation of the magnetic disk, the number of circuit parts for controlling the current in the motor drive circuit is required to start the spindle motor in order to start the motor, and in order to improve the starting characteristics of the motor, fine drive control and contact start stop (hereinafter In order to realize a large current drive for quickly completing (CSS), it is required to complicate and increase the size of the current control circuit.

It is an object of the present invention to provide a magnetic disk device in which a large number of HDAs are mounted in the magnetic disk device, and the magnetic disk device is manufactured at a low cost to reduce the bit cost.

[0007]

In order to achieve the above object, in a magnetic disk device of the present invention, a power source unit for converting an input voltage from the outside of the device into a predetermined voltage, and a drive current control for controlling a spindle motor energization current. Section, a power source selection section for switching electricity supplied to the motor drive circuit to the power source section or the drive current control section, a plurality of motor drive circuit sections,
It is composed of multiple HDAs.

At the time of starting the motor, by the above means, the power source selecting unit selects the power source from the drive current control unit to the motor drive circuit unit of the HDA to be started,
The drive current control unit controls the current so that the motor drive of the HDA is optimized, and the power source selection unit at the time of completion of start-up selects to transmit power directly from the power source unit to the motor drive circuit unit to cause steady rotation. Control means for sequentially performing this operation on a plurality of HDAs to start the motor.

[0009]

The function of the present invention will be described.

An HDA for starting the spindle is selected by a controller that controls the drive when the magnetic disk device is powered on. The power source selection unit energizes the corresponding HDA from the power source to the motor drive circuit unit via the drive current control unit. The drive current control unit performs optimum drive for CSS, and after completion of activation, the drive current control unit is selected for the HDA to be activated next by the power source selection means. With the above operation, the spindle motor of the HDA is optimally activated to activate the spindle of the magnetic disk device without damaging the magnetic head and the magnetic disk.

[0011]

EXAMPLE In an HDA for CSS, there is a wear effect between the magnetic head and the disk before the magnetic head starts to fly. Therefore, it is desirable that the spindle motor is started to rotate to a steady rotational speed immediately after the start of startup. On the other hand, there is a possibility that the magnetic head is sticking due to the lubricant on the magnetic disk when the rotation is stopped. The magnetic head suspension may be damaged.

In order to remedy this problem, the magnetic disk drive of the present invention has the structure shown in FIG. As shown in FIG. 3, a plurality of (four in FIG. 1) HDA: 5 are used in common with the motor drive current control means: 2 required only at the time of starting. Therefore, by sharing the motor drive current control means: 2, it is possible to cope with the increase in size and complexity of the circuit section.

FIG. The invention will be described in more detail.

A power supply unit for converting an external AC power supply into a predetermined voltage: 1, a control unit for controlling a motor drive and the like: 6, a drive current control unit for controlling a motor drive current at startup: 2, a phase for energizing a motor The driving circuit for switching the driving circuit: 4 and the means for selecting the power supply to the driving circuit: 3.

The operation will be described. First, the controller: 6 selects HDA: 5 to be activated. Selected HDA: 5
On the other hand, the control section: 6 selects the power supply selection means: 3 so that the drive circuit: 4 is supplied with power from the drive current control section: 2. Next, the control unit starts the HDA: 5 spindle motor: 5a and gradually increases the motor drive current until the change in the inductance of the motor coil, the back electromotive force of the motor, or the start of rotation is detected by the Hall element.

After the motor rotation is detected, the control unit 6 gives a command to the drive current control unit 2 so that a large current is supplied. According to this command, the motor drive circuit: 4 is the HDA spindle motor: 5
When a large current is applied to a, the magnetic head starts flying from the magnetic disk in a short time.

FIG. An example of a three-phase Y-connection spindle motor drive circuit is shown in FIG. When the magnetic disk is rotated at a constant rotation speed, the driving current is small and the load on the driving circuit is small even with a constant voltage power supply from the power supply. Transistor: 4
In the case of PWM control by applying a switch signal to the bases of a and 4b, the load on the drive circuit is further reduced, and current control at start-up is not considered. The driving circuit of (3) has a small load and can be made compact.

FIG. 3 shows the motor starting characteristic according to the present invention. Will be explained.

When the current limiting at the time of starting is performed by the series resistor without using the present invention, the motor energizing current at the time of starting is I1 and the rotation speed rising characteristic is ω1. As the motor energization current increases, the counter electromotive voltage increases, the energization current decreases, and the start-up of rotation deteriorates.

On the other hand, claim 1. The motor starting characteristic according to the invention is that the motor energizing current for starting is I2 and the rotation speed rising characteristic is ω2. This is because the voltage applied to the motor drive circuit is controlled so that the voltage is reduced when the rotation speed is low and the applied voltage is increased when the rotation speed is high, and the rotation speed has risen sufficiently (1/2 of the steady rotation speed). In the above), the energizing current decreases, but this is because the back electromotive voltage becomes large due to the increase in the number of revolutions and the constant current cannot be supplied to the power supply.
However, since the rotation speed has risen sufficiently, there is no effect on the damage to the magnetic head / disk.

Further, the motor starting characteristics according to the first, second, and third aspects of the invention are that the motor energizing current at starting is I3 and the rotation speed rising characteristic is ω3. At the time of start-up, the motor drive current control circuit: 2 gradually increases the motor current, and the spindle motor does not rotate until the adhesive torque of the magnetic head / disk is exceeded, and the torque generated by the motor exceeds the adhesive torque of the magnetic head / disk. When the rotation is started, the start-up is performed with a large current as in the above I2.

The effect of the start-up is that when the motor rotation speed rising characteristics ω1 and ω2 are compared, the time until the magnetic head starts to fly from the magnetic disk is longer at ω1 and the flying start rotation speed is equal to the steady rotation speed. When it is set to 1/2, the time until ω2 starts to fly can be reduced by 40% of ω1, and thus damage to the magnetic disk during CSS can be reduced. Further, when comparing ω1 and ω3 of the motor rotation speed rising characteristic, when a large current is supplied to the motor at a start at ω1 at the time of start-up and there is an adhesive action between the magnetic head and the magnetic disk, the spring part supporting the magnetic head Although there is a risk of damage, at ω3, the energizing current is gradually increased so that the rotation starts slowly until the adhesion is released, so the magnetic disk rotates without damaging the spring part that supports the magnetic head. It becomes possible to start. After releasing the adhesion, by applying the same starting current as the starting of ω2,
The time during which the magnetic head is rubbed without floating on the magnetic disk is short, and damage to the magnetic disk during CSS can be reduced.

[0023]

According to the present invention, the drive current controller controls the spindle motor drive when the magnetic disk starts rotating.
The load on the magnetic head / disk is reduced at this time, and the reliability of the magnetic head / disk can be improved.

Further, by making the circuit section which is used only at the time of starting the motor common, it becomes possible to make the whole apparatus compact and to reduce the cost. Especially, in the collective type magnetic disk apparatus in which a large number of HDAs are mounted in the apparatus, the motor is started. The common use of the circuit section has the effect of enabling high-density mounting.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a configuration of the present invention, in which four HDAs are mounted in one magnetic disk device.

FIG. 2 is a diagram showing an example of a drive circuit for a spindle motor of the present invention.

FIG. 3 is a diagram showing a starting current and a rotation rising characteristic of a conventional spindle motor and showing a starting current and a rotation rising characteristic of a spindle motor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Power supply, 2 ... Current control part, 3 ... Power supply selection part, 4 ... Drive circuit, 4a ... Transistor (PNP), 4b ... Transistor (NPN), 5 ... HDA, 6 ... Control part, I1 ... Conventional starting current Waveform examples, I2, I3 ... Starting current waveform of the present invention, ω1 ... Conventional rotation start-up characteristics, ω2, ω3 ... Rotation start-up characteristics of the present invention.

Claims (3)

[Claims] 1. A magnetic disk drive apparatus having at least two head disk assemblies for recording / reproducing information by rotating a magnetic disk, the head disk assembly having a spindle motor, and a circuit for driving the motor. , A means for selecting a power supply route to be supplied to the circuit, a current control means used only when the motor is started, and a power supply for applying a predetermined voltage. Power is supplied to the means, the control means controls the starting current to the motor drive circuit of the head disk assembly selected by the power supply selecting means, and after the completion of the starting operation of the motor, the power supply selecting means switches to a constant voltage power supply. Motor drive of head disk assembly that should be started up after being steadily rotated The power source selection means is switched so that the current is supplied to the path from the current control means, the starting current is controlled and supplied to the motor drive circuit, the starting operation is performed, and the above operation is performed for a plurality of HDAs. A magnetic disk drive device which is activated by current control means. 2. The magnetic disk drive according to claim 1, wherein the voltage / current control means supplies a current to the magnetic head spring force (N) × until the rotation start of the spindle motor is detected.
Number of magnetic heads (number) x radial position of magnetic head on magnetic disk (m) / motor torque constant (Nm / A) [A
/ Sec] or less, a current is applied to the spindle motor at an increasing rate, and after the rotation of the spindle motor is detected, the magnetic disk steady-state rotation speed (rps) x spindle inertia moment (N
m · sec ² ) / motor torque constant (N · m / A) / 3
[A] A magnetic disk drive device characterized by activating a spindle motor by supplying a current of the above value. 3. The magnetic disk device according to claim 1, wherein the rotation detecting means detects rotation by a change in inductance of a motor coil, a back electromotive force generated in the motor, and a Hall element. Disk drive.