JP2731206B2 - Magnetic disk drive - Google Patents

Description

The present invention relates to a magnetic disk drive used as an external memory of a system, and in particular, to consumption when a voltage drop occurs when a battery power supply is used. The present invention relates to a magnetic disk drive suitable for suppressing power.

(Prior Art) In a magnetic disk drive, a magnetic recording medium (disk) is rotationally driven by a spindle motor, and a magnetic head is sought in a radial direction of the disk to read / write data. The magnetic head is mounted on a carriage, and the carriage is driven by a voice coil motor to seek on the disk.

By the way, in the magnetic disk device, it is necessary to drive the spindle motor and the voice coil motor at the time of reading / writing data as described above, so that the power consumption becomes large.

Specifically, as shown in FIG. 3, the total current consumption is the sum of the current consumption Ib of the voice coil motor, the current consumption Is of the spindle motor, and the current consumption Ia of the other circuits. Here, for seek control of the magnetic head,
There are acceleration, constant speed, and deceleration modes, but at constant speed, the current consumption Ib of the voice coil motor is almost “0”.
The current consumption Ib of the voice coil motor is determined during acceleration and deceleration. Therefore, the maximum value Imax of the current consumption of the entire magnetic disk device is also the current consumption Ib of the voice coil motor.
Is determined by the temporary value of the maximum value Amax.

Nowadays, magnetic disk drives are mounted as external memories of a system and are often supplied with power from a battery power source such as a battery.
When the maximum value Amax of the current consumption Ib of the voice coil motor flows as usual when the voltage of the battery power drops, there is a problem that the battery is accelerated and the operation of the entire system becomes impossible. .

(Problems to be Solved by the Invention) As described above, the current consumption of the voice coil motor is the same even when the voltage of the battery power source drops, so that the voltage drop at that time is accelerated. there were.

The present invention has been made in view of the above points, and provides a magnetic disk drive capable of effectively using battery power while suppressing power consumption when the power supply voltage is reduced when supplying power from battery power. With the goal.

[Structure of the Invention] (Means for Solving the Problems) That is, a magnetic disk device according to the present invention is a magnetic disk device that operates by receiving power supply from a battery power supply, and a motor for driving a carriage having a magnetic head mounted thereon. A motor driving means for supplying a driving current to the motor; a power supply voltage monitoring means for monitoring a voltage of the battery power supply and outputting a voltage drop signal when the voltage drops below a predetermined level; A target speed calculating means for calculating a target speed, and when the voltage drop signal is output from the power supply voltage monitoring means, a target speed generating means for suppressing the target speed to a specific level; and a target speed obtained by the target speed generating means. Control signal output means for outputting a drive control signal according to a difference between the drive control signal and the actual moving speed of the magnetic head; Controlling the drive current supplied to the motor by the motor drive means based on the drive control signal output by the signal output means, and when the voltage drop signal is output from the power supply voltage monitoring means, A drive current suppressing means for suppressing the drive control signal to a specific level.

(Operation) According to the above configuration, when the voltage of the battery power supply drops, the time required for acceleration and deceleration with large current consumption is reduced, and at that time, a lower drive current is supplied to the motor. It is possible to perform seek control while suppressing power consumption.

Hereinafter, a magnetic disk drive according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the circuit configuration, and a voice coil motor (hereinafter referred to as VCM) 11 is a motor for driving a carriage on which a magnetic head (not shown) is mounted. The VCM driver 12 supplies a drive current to the VCM 11. The power supply voltage monitoring circuit 13 monitors the power supply voltage of this device, and when detecting that the voltage has dropped to a predetermined level, outputs a voltage drop signal. The power supply is
It is a battery power source such as a battery. Drive current suppression circuit 14
Suppresses the drive current supplied to the VCM 11 to a specific level when the power supply voltage monitoring circuit 13 detects a voltage drop.

The target speed creation circuit 15 performs acceleration corresponding to the number of remaining cylinders up to the target cylinder when seeking the magnetic head,
A target speed for performing constant speed and deceleration is calculated, and when a voltage drop is detected by the power supply voltage monitoring circuit 13, the calculated target speed is suppressed to a specific level. The position signal creating circuit 16 creates a position signal corresponding to the current position on the disk when the magnetic head is seeking, based on the servo signal read from the disk (not shown). The moving speed detecting circuit 17 differentiates the position signal output from the position signal generating circuit 16, detects the actual moving speed when the magnetic head is seeking, and outputs a moving speed signal. The operational amplifier 18 compares the target speed signal from the target speed generating circuit 15 with the moving speed signal from the moving speed detecting circuit 17, and outputs a drive control signal according to the error.

 Next, the operation of the embodiment will be described.

First, when a seek command is output from a host computer (not shown), seek control of the magnetic head is started.
That is, the carriage is driven, and positioning control for seeking the magnetic head to the target cylinder on the disk is started.

Here, the target speed creation circuit 15 creates a target speed according to the error between the target cylinder to which the magnetic head should move and the current position, and generates a target speed signal (voltage signal) Vd as shown in FIG. 4, for example. Output. Specifically, the target speed creation circuit
A step 15 obtains a moving distance (the number of cylinders) corresponding to an error between the target cylinder and the current cylinder, and searches a target speed table stored in advance for target speed data (digital signal) corresponding to the moving distance. Then, the target speed data is converted into an analog target speed signal Vd and output. At this time, when the voltage drop signal is output from the power supply voltage monitoring circuit 13, the target speed calculated as described above is suppressed to a specific level, and the target speed is suppressed to the level Vl as shown in FIG. Outputs the speed signal Vd.

On the other hand, at this time, the moving speed detecting circuit 17 outputs a moving speed signal Vh corresponding to the actual moving speed of the magnetic head as shown in FIG. 5, and the operational amplifier 18 outputs the target speed signal Vd and the moving speed signal Vh. A drive control signal (voltage signal) corresponding to the difference is output to the drive current suppression circuit 14.

The drive current suppression circuit 14 suppresses the drive control signal from the operational amplifier 18 to a specific level as shown in FIG. 6 only when the voltage drop signal is output from the power supply voltage monitoring circuit 13, and sets this to the VCM driver. Output to 12. The drive current suppressing circuit 14 is composed of a limiter in which an operational amplifier 21 is connected to a diode feedback circuit 22 for gain control, as shown in FIG. 2, for example. This limiter operates via a switch 23 which is turned on by the input of a voltage drop signal,
The output is suppressed at a specific level.

The VCM driver 12 supplies a drive current I as shown in FIG. 7 to the VCM 11 based on the drive control signal. This allows
The carriage is driven, and the magnetic head seeks on the disk.

In this case, the magnetic head is driven by the seek control as described above to accelerate the period Ta, the constant speed period Tb,
The vehicle moves at the moving speed Vh including the deceleration period Tc.
As shown in FIG. 7, the VCM driver 12 supplies drive currents I in the opposite directions to the VCM 11 during the acceleration period Ta and the deceleration period Tc in the seek. In the constant speed period Tb, since the moving speed of the magnetic head has reached the target speed, the drive current I is almost “0”.

Here, comparing the normal leak control and the seek control at the time of the voltage drop, the drive current is as shown in FIG. 8, the solid line is the normal time, the dotted line is the voltage drop, and the acceleration and deceleration periods are at the time of the voltage drop. Is reduced, and its maximum value is suppressed. The moving speed is as shown in FIG. 9. The solid line is normal and the dotted line is when the voltage drops. When the voltage drops, the target speed is quickly reached and the constant speed period becomes longer. Therefore, in the state where the voltage of the battery power source is lowered, although the seek speed is reduced, the power consumption is suppressed, and the battery power source is used effectively, and the battery power source operates longer than before.

[Effects of the Invention] As described above, according to the present invention, when the battery power is reduced to a predetermined level, the target speed of the seek control is suppressed to a specific level, and the drive control signal of the motor according to the target speed is controlled. To a specific level,
When power is supplied from a battery power supply, power consumption when the power supply voltage is reduced can be suppressed, and the battery power supply can be used effectively.

[Brief description of the drawings]

The drawings are for illustrating one embodiment of the present invention,
FIG. 1 is a block diagram showing a circuit configuration, FIG. 2 is a diagram showing a configuration of a drive current suppressing circuit, FIG. 3 is a diagram showing a relationship between current consumption and time during a seek, and FIG. 4 is a target speed. FIG. 5 is a diagram showing a relationship between a moving speed and time, FIG. 6 is a diagram showing a relationship between a drive control signal and time,
FIG. 7 is a diagram showing the relationship between drive current and time, FIG. 8 is a diagram showing the difference in drive current between normal seek and voltage drop seek, and FIG. 9 is a diagram showing normal seek and voltage drop seek. FIG. 6 is a diagram showing a difference in the moving speed of the robot. 11… VCM (voice coil motor), 12… VCM driver, 13
... Power supply voltage monitoring circuit, 14 ... Drive current suppression circuit, 15 ... Target speed creation circuit, 16 ... Position signal creation circuit, 17 ... Moving speed detection circuit, 18 ... Op amp.

Claims (1)

(57) [Claims] 1. A magnetic disk drive which operates by receiving power supply from a battery power supply, a motor for driving a carriage on which a magnetic head is mounted, motor driving means for supplying a drive current to the motor, and a voltage of the battery power supply And a power supply voltage monitoring means for outputting a voltage drop signal when the voltage drops below a predetermined level; calculating a target speed of the magnetic head; and outputting the voltage drop signal from the power supply voltage monitoring means. A target speed generating means for suppressing the target speed to a specific level, and a drive control signal corresponding to a difference between the target speed obtained by the target speed generating means and the actual moving speed of the magnetic head. Drive control signal output means for performing the motor drive based on the drive control signal output by the drive control signal output means. A driving current supplied to the motor by a stage, and a driving current suppressing means for suppressing the driving control signal to a specific level when the voltage drop signal is output from the power supply voltage monitoring means. A magnetic disk drive characterized by the above-mentioned.