JP2000113583A - Disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk device capable of stopping a spindle within a shortest time after a sure retracting operation at the time of power cut. SOLUTION: The rotation of a spindle motor 1 is controlled by a spindle motor driving circuit 2. A circuit for braking a spindle is incorporated in the spindle motor driving circuit 2, and the braking is controlled according to the level of a braking signal (b). The braking is applied when the braking signal (b) becomes equal to a fixed level or lower. Counter electromotive force obtained for each rotation of the spindle motor 1 is outputted as a back electromotive voltage (a), supplied to a retracting circuit 3, and used as a retracting voltage at the time of power cut. A brake timing circuit 4 is composed of nothing but resistors R1 and R2, and the partial pressure of resistance for the back electromotive voltage (a) is inputted to the spindle motor driving circuit 2 as a braking signal (b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a disk drive, and more particularly to a magnetic disk drive having a retract function.

[0002]

2. Description of the Related Art Normally, in a (for example, magnetic) disk drive, a (for example, magnetic) disk medium for recording data is rotated at a constant rotational speed by a spindle motor, and a read / write for reading / writing data is performed. The (for example, magnetic) head floats by a fixed amount (small interval) from the upper surface of the disk medium by a floating force obtained by rotation of the disk medium. Therefore, when the disk medium is at a certain rotational speed or less, the levitation force is reduced, and the magnetic head cannot obtain a sufficient floating amount and comes into contact with the disk medium. In the state of contact between the disk medium and the magnetic head, a crash (destruction of the medium) may occur. For this reason, the shorter this contact time,
The read reliability of the recording data written on the magnetic head and the disk medium is improved.

In order to prevent data destruction due to the magnetic head coming into contact with the disk medium, a dedicated contact area called a CSS (contact start / stop) zone is provided on the disk medium. No recording data is written, and when the spindle motor is started and stopped, a retract operation for positioning the magnetic head in this CSS zone is required. In the retract operation of the magnetic head, the carriage on which the magnetic head is mounted is often driven using a solenoid.

For the reasons described above, the following measures are required when the spindle motor is stopped. First, in order to stop the disk medium within a short time for the purpose of improving reliability, a brake is required when the spindle motor stops.
Usually, as this braking method, a method is used in which the driving end of a coil for rotating and driving the spindle motor is short-circuited, and the back electromotive force due to rotation is short-circuited to be used for braking.

On the other hand, since it is necessary to retract the magnetic head to the CSS zone, usually, the power (source) for driving the spindle motor is stopped, and then the retract operation is performed, and then the brake is applied to the spindle motor. A multiplication sequence is taken.

While the power supply is energized, the above-described sequence can be executed while always monitoring the operation state, so that there is no problem. However, the operation state cannot be monitored when the power supply is cut off (particularly during power failure).
Therefore, the spindle drive stop and the retract operation are
This is performed in a state where there is no power supply.

Japanese Unexamined Patent Publication (Kokai) No. 3-259479 proposes a method of executing a retract operation using a back electromotive force of a spindle motor. However, this alone cannot brake the spindle.

Since the braking operation needs to be performed after a lapse of time necessary for the retraction operation,
Conventionally, as shown in FIG. 3, the timing is determined by utilizing the discharge time of the electric charge stored in the capacitor C.
That is, when the power is turned off, the back electromotive force a of the spindle motor 1 is first applied to the retraction circuit 3 via the spindle drive circuit 2, and the magnetic head (not shown) is retracted.

Next, in the brake timing circuit 4, the electric charge stored in the capacitor C is discharged through a time constant circuit composed of the capacitor C and the resistors R3 and R4, so that the terminal voltage of the capacitor C becomes constant. When the value decreases to a value, a brake signal b is output, the back electromotive force of the spindle motor is short-circuited via the spindle drive circuit 2, and the spindle is braked.

[0010]

However, in the conventional disk drive shown in FIG. 3, the brake operation start timing for stopping the spindle motor when the power is turned off is determined by the discharge time of the electric charge stored in the capacitor. Therefore, there is a problem that the suspension time of the spindle after the power is turned off becomes long or the rotation of the spindle motor becomes slow during the retraction operation due to the variation in the capacitance value of the capacitor, and a sufficient magnetic head flying height cannot be obtained. there is a possibility.

In this case, a large-capacity capacitor such as an electrolytic or electric double-layer capacitor is used as the capacitor, but it is inevitable that these large-capacity capacitors have large variations in capacitance value.

An object of the present invention is to provide a disk device which stops a spindle in the shortest time after a retraction operation without fail when power is turned off.

[0013]

According to the present invention, there is provided a disk apparatus comprising: a head retract means for retracting a write / read head by a back electromotive force of a spindle motor for driving a disk medium to rotate when a power source is turned off; Back electromotive voltage detection means for detecting a voltage value of electric power, and brake control means for applying a brake to the spindle motor from the time when the voltage value of the back electromotive force of the spindle motor drops below a certain value. I do.

Further, the head retract means retracts the write / read head to a contact start / stop zone of the disk medium. Further, the head retract means drives a carriage to which the write / read head is attached by a solenoid. Still further, the back electromotive voltage detecting means detects the back electromotive force of the spindle motor by resistance division.
Then, the brake control means short-circuits the drive coil of the spindle motor.

The operation of the present invention is as follows. When the power is turned off, first, the back electromotive force of the spindle motor is applied to the retract circuit, and the magnetic head is retracted. next,
When the voltage value of the back electromotive force (back electromotive voltage) decreases to a certain value, a brake signal is output, the back electromotive force of the spindle motor is short-circuited, and the spindle is braked.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment relating to a retract operation of a magnetic head and a brake operation for a spindle of a disk drive according to the present invention, and parts equivalent to those in FIG.
In FIG. 1, a circuit relating to a retract operation of a magnetic head of a disk device according to the present invention and a brake operation for a spindle includes a spindle motor 1 for rotating a disk medium via a spindle, a spindle motor 1
Has a spindle drive circuit 2 for energizing and driving the drive coil. Further, the system includes a retract circuit 3 for retracting a magnetic head (not shown) and a brake timing circuit 4 for generating a brake signal b for giving a timing for applying a brake to the spindle (motor 1).

The operation of the embodiment of the present invention will be described. FIG. 2 is a graph illustrating the optimal spindle brake timing. In FIG. 2, the horizontal axis represents time, and the vertical axis represents spindle speed, and represents a change in stop characteristics due to a change in brake timing. It can be seen that when the brake timing is early, the rotation speed becomes lower than the revolving speed of the head during the retraction operation, and when the brake timing is too late, the stop time increases.

In FIG. 1, the rotation of a spindle motor 1 is controlled by a spindle motor drive circuit 2. A circuit for applying a brake to the spindle is built in the spindle motor drive circuit 2, and the brake is controlled by the level of the brake signal b. In the case of this figure, the brake is applied when the brake signal b falls below a certain level. The back electromotive force obtained by the rotation of the spindle motor 1 is output as a back electromotive voltage a, is supplied to the retract circuit 3, and when the power supply is turned off, the retract voltage (the power supply for retracting the magnetic head to the CSS zone). )
Used as The brake timing circuit 4 according to the present invention includes only resistors R1 and R2, and a voltage obtained by dividing the back electromotive voltage a by resistance is input to the spindle motor drive circuit 2 as a brake signal b.

With such a circuit configuration, when the level of the back electromotive voltage a drops below a certain value when the power is turned off, the spindle is braked at that timing. Therefore, the control from the spindle drive circuit 2 is stopped, the variation in the period during which the spindle motor 1 coasts is reduced, and by using the resistors R1 and R2 with high accuracy, the spindle motor 1 can be controlled at an optimum time. Can be stopped.

[0020]

As described above, according to the present invention, the brake timing for stopping the spindle motor when the power is turned off is determined based on the back electromotive force level generated by the rotation of the spindle motor, and the magnetic head is thus determined. (carriage)
However, there is an effect that the flying condition for retracting is sufficiently satisfied, the variation of the stop time due to the variation of the electronic components is small, and the spindle motor is stopped at an optimum time.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a brake timing according to the embodiment of the present invention.

FIG. 3 is a block diagram of an example of a conventional brake timing generation circuit.

[Explanation of symbols]

 1 spindle motor 2 spindle drive circuit 3 retract circuit 4 brake timing circuit

Claims (5)

[Claims] 1. A head retract means for retracting a write / read head by back electromotive force of a spindle motor for rotating a disk medium when power is turned off,
Back electromotive voltage detection means for detecting the voltage value of the back electromotive force of the spindle motor, and brake control means for applying a brake to the spindle motor from the time when the voltage value of the back electromotive force of the spindle motor drops below a certain value. A disk device comprising: 2. The disk drive according to claim 1, wherein said head retracting means retracts said write / read head to a contact start / stop zone of said disk medium. 3. A disk drive according to claim 1, wherein said head retracting means drives a carriage to which said write / read head is attached by a solenoid. 4. The disk device according to claim 1, wherein said back electromotive voltage detecting means detects the back electromotive force of said spindle motor by resistance division. 5. The disk device according to claim 1, wherein said brake control means short-circuits a drive coil of said spindle motor.