KR100233126B1 - Control circuit and method of spindle motor of disk drive - Google Patents

Abstract

end. The technical field to which the invention described in the claims belongs

The present invention relates to a circuit for braking and stopping a spindle motor during driving in a disk drive employing a CSS method and a control method thereof.

I. The technical problem to be solved by the invention

It provides a circuit and control method to stop the spindle motor quickly even in the power saving mode.

All. Summary of Solution of the Invention

When the spindle motor is in the power saving mode during the normal rotation, the frequency of the drive clock applied to the spindle motor driver is changed to the braking frequency set lower than the normal frequency, and the spindle motor turns to the speed corresponding to the braking frequency. The braking time of the spindle motor is reduced by disabling the motor driver.

la. Important uses of the invention

It is used to stop the spindle motor quickly when going to sleep mode.

Description

Spindle motor braking circuit of disk drive and its control method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive employing a Contact Start Stop (CSS) method, and more particularly, to a circuit for stopping and stopping a spindle motor during driving and a control method thereof.

Typically, in a disk drive such as a hard disk drive (HDD), a disk for storing digital information is rotated by a spindle motor. The spindle motor is driven by a spindle motor driver controlled by a microcomputer (hereinafter referred to as a "microcom") which is used as a main drive of a disk drive. The spindle motor driver is provided by a one-chip integrated circuit (IC), and rotates the spindle motor at a constant speed at a constant speed. The target speed varies from disk drive to disk drive, for example 5400 RPM. Such a disc drive is configured to record / read digital information on a disc by a head flying on the disc while the disc rotates at a constant speed. At this time, the head rises from the disk by the airflow generated by the rotational force of the spindle motor.

In this way, when the power source is " off " while the disk is rotating at constant speed, that is, the spindle motor is running at constant speed, the spindle motor is stopped. At this time, the spindle motor does not stop immediately when the power is "off", but stops completely after a certain time, typically several tens of seconds, as the rotational speed gradually decreases from the time when the power is "off".

On the other hand, the disk drive employing the CSS method, when the power is "off", the head is moved to the parking zone (parking zone) specially provided on the disk to park. In this way, when the head is parked, the head gradually decreases as the rotational speed of the spindle motor decreases. Typically, the rotational speed of the spindle motor at which the head starts to descend, that is, the head descending speed, is about 1500 RPM, and when it is lowered to about 1000 RPM, the head lands completely on the disk. At this time, since the disk is still rotating, the head and the disk are damaged by the impact and friction caused by the collision with each other until the disk is completely stopped. This damage is exacerbated as time elapses from when the power is "off" until the spindle motor is completely stopped.

Accordingly, disc drives have employed separate braking circuits to minimize damage to the heads and discs as described above upon power " off ". The braking circuit is active when the power is "off" and brakes the spindle motor, which typically completely stops the spindle motor within 5 seconds from the time the power is "off". The head remains injured for 5 seconds by the force of the airflow even when the spindle motor is gradually lowered than the prescribed rotation speed. This allows the spindle motor to be completely or nearly stopped by the braking circuit before the head lands on the disc, thereby minimizing damage to the head and disc as described above.

On the other hand, a personal computer employing a disk drive (hereinafter referred to as a "PC") has a power saving function to prevent unnecessary power consumption when the user does not use the PC for a long time without turning the main power off. That's the trend. Accordingly, the disk drive also has a power saving mode such as a standby mode and a sleep mode to reduce unnecessary power consumption. When entering the power saving mode, the disk drive microcomputer stops the drive of the spindle motor by disabling the spindle motor driver and simultaneously parks the head. At this time, however, since the power supply is still in the "on" state, the braking circuit becomes inactive, so that braking is not performed, resulting in damage to the head and disk as described above.

As described above, in the related art, the braking circuit is operated when the power is "off", but the braking circuit is not operated when the power saving mode is activated, thereby seriously damaging the head and the disk.

Accordingly, an object of the present invention is to provide a spindle motor braking circuit and a control method thereof capable of quickly stopping the spindle motor even when the power saving mode is switched.

1 is a spindle motor braking circuit diagram according to an embodiment of the present invention,

2 is an operation waveform diagram of the comparator of FIG.

3 is a control flowchart according to an embodiment of the present invention;

4 is a speed change state diagram of the spindle motor according to the control of FIG.

5 is a control flowchart according to another embodiment of the present invention;

6 is a speed change state diagram of the spindle motor according to the control of FIG.

The present invention for achieving the above object is the rotational speed of the spindle motor after changing the frequency of the drive clock applied to the spindle motor driver lower than the normal frequency when the spindle motor is switched to the power saving mode during the normal rotation The spindle motor driver is disabled when the speed corresponds to the braking frequency.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention, such as specific circuit configurations, flow charts, logic states, operating waveforms, rotation speeds, and the like. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. And a detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 shows a braking circuit diagram of a spindle motor according to an embodiment of the present invention. The clock generator 100 generates a drive clock SCLK having one of a normal frequency and a braking frequency under the control of the microcomputer 106 of the control unit 110, which is composed of the microcomputer 106 and the comparator 108. Is applied to (102). The stationary frequency refers to a frequency at which the spindle motor 104 rotates at a constant speed, that is, 5400 RPM in the above example, and the braking frequency is a frequency set lower than the stationary frequency according to the present invention as described below. In order to change the frequency of the driving clock SLCK as described above, the clock generator 100 generates two frequency signals using two crystal oscillators, and selects and outputs one under the control of the microcomputer 106. Alternatively, the clock generation unit 100 may divide one fundamental frequency signal into different division ratios, generate a signal having two frequencies, and then select one to be output under the control of the microcomputer 106. As such, generating a clock by selectively changing the frequency is well known in the art, and thus a detailed description thereof will be omitted. The spindle motor driver 102 inputs the driving clock SCLK applied from the clock generator 100 to apply a driving signal having a period corresponding to the frequency to the spindle motor 104 to drive the spindle motor 104. At this time, the spindle motor driver 102 and the spindle motor 104 are connected with different phases U, V, W, and N represents a neutral terminal. The spindle motor driver 102 is enabled or disabled by the microcomputer 106. While in the normal mode, the microcomputer 106 enables the spindle motor driver 102 and controls the clock generator 100 to generate the frequency of the driving clock SCLK at the normal frequency in the normal mode. In this state, when switching to the power saving mode, the microcomputer 106 controls the clock generator 100 to change the driving clock SCLK to the braking frequency, and then when the rotational speed of the spindle motor 104 becomes a speed corresponding to the braking frequency. Disable the spindle motor driver 102. At this time, the microcomputer 106 detects the rotational speed of the spindle motor 104 from the period of the square wave signal input from the comparator 108. As described above, the microcomputer 106 uses a microcomputer provided as a main controller in a conventional disk drive.

Here, the rotation speed detection of the spindle motor 104 using the comparator 108 will be described in detail. First, the signal waveforms appearing in the three phases U, V, and W appear as shown in FIGS. 2A, 2B, and 2C, respectively, and have a period proportional to the rotational speed of the spindle motor 104. . Therefore, the rotational speed of the spindle motor 104 can be known by examining the period of the signal appearing in any phase among the three phases U, V, and W of the spindle motor 104. 1 shows an example of using phase U among three phases U, V, and W. That is, the non-inverting input terminal (+) of the comparator 108 is connected to the phase U of the spindle motor 104, and the inverting input terminal (-) is connected to the neutral terminal N in which a signal having a waveform as shown in FIG. The output terminal is connected to the microcomputer 106. The comparator 108 then compares the levels of the two input signals as shown in FIG. 2E and generates a square wave signal as shown in FIG. 2F according to the comparison result. By counting the period of the square wave signal, the microcomputer 106 can check the rotational speed of the spindle motor 104. As such, checking the speed by counting the period of the square wave signal is well known in the art, and thus a detailed description thereof will be omitted.

In order to rotate the spindle motor 104, the drive clock SCLK must be applied to the spindle motor driver 102 from the outside at a predetermined frequency corresponding to the prescribed target speed. Accordingly, in the normal mode, the microcomputer 106 controls the clock generator 100 such that the driving clock SCLK has the normal frequency as in the normal case. The spindle motor driver 102 then drives the spindle motor 104 at a constant rotational speed by the drive clock SCLK.

In this state, when switched to the power saving mode, the microcomputer 106 performs the control operation according to FIG. 3, which shows a control flowchart according to an embodiment of the present invention. First, the microcomputer 106 controls the clock generator 100 at step 300 to change the frequency of the driving clock SCLK to the braking frequency. At this time, the braking frequency is set lower than the normal frequency as described above, and the rotational speed of the spindle motor 104 is braked because the rotational speed of the spindle motor 104 is proportional to the frequency of the driving clock SCLK applied to the spindle motor driver 102. It drops sharply with frequency. The braking frequency is preferably set to a frequency corresponding to the lowest response speed of the spindle motor 104. This is because the lower the frequency of the drive clock SCLK, the lower the rotational speed of the spindle motor 104, but the lower the response speed, the lower the frequency of the drive clock SCLK. This lowest response speed depends on the characteristics of the spindle motor 104 and the spindle motor driver 102 used for each disk drive, which is typically lower than 1000 RPM, the speed at which the head will land completely on the disk. Therefore, the actual value of the braking frequency is set according to the characteristics of the spindle motor 104 and the spindle motor driver 102 used in the disk drive.

As described above, when the frequency of the driving clock SCLK is changed to the braking frequency when the power saving mode is lowered, the rotation speed of the spindle motor 104 is rapidly increased by the spindle motor driver 102 even if the braking circuit is not operated. The braking time of the spindle motor 104 is shortened by lowering to the lowest response speed of the 104. 4 shows a speed change state of the spindle motor 104. Figure 4 shows the speed down state of the spindle motor 104 when the spindle motor 104 is rotated at 5400 RPM at a constant speed when the power saving mode is changed at time t0, the normal speed is 5400 RPM and the lowest response speed is 500 RPM Listened.

After the frequency of the driving clock SCLK is changed to the braking frequency in step 300, the microcomputer 106 checks the rotational speed of the spindle motor 104 from the output of the comparator 108 in steps 302 to 304. do. At this time, if the rotational speed of the spindle motor 104 drops to 500 RPM, which is the lowest response speed as in the time point t1 of FIG. 4, the microcomputer 106 disables the spindle motor driver 102 in the step 306 as usual. After exiting, it performs normal power saving mode. Then, the spindle motor 104 is completely stopped at the time t2 of FIG.

Therefore, in the related art, when the braking circuit is not operated when the power saving mode is switched, the rotation speed of the spindle motor 104 is gradually lowered as shown in the curve S2 of FIG. 4, but the braking time is long. As the frequency is changed to the braking frequency, even though the braking circuit is not operated, the speed of the spindle motor 104 is rapidly lowered to 500 RPM as shown in the curve S1, thereby shortening the braking time. Therefore, it is possible to minimize the damage of the head and the disk due to the head parking when entering the power saving mode.

On the other hand, as described above, braking the spindle motor 104 is suitable when the torque of the spindle motor 104 is small, but the torque of the spindle motor 104 is large. It is desirable to lower the rotational speed to the head lowering speed first and then change it to the frequency corresponding to the lowest response speed. That is, if the frequency of the drive clock SCLK is lowered in two stages, braking is performed more quickly even when the torque of the spindle motor 104 is large.

In order to reduce the frequency of the driving clock SCLK in two steps, the clock generator 100 of FIG. 1 is changed to generate three frequencies, that is, the normal frequency and the first and second braking frequencies. That is, as described above, the clock generator 100 generates three frequency signals using three crystal oscillators or divides one basic frequency signal at different division ratios to create a signal having three frequencies, and then the microcomputer 106. Under the control of) to select and output one. In an embodiment of the present invention, the first braking frequency is set to a frequency corresponding to the head lowering speed, and the second braking frequency is set to a frequency corresponding to the lowest response speed. The microcomputer 106 programs the braking control operation according to the flowchart of FIG. 5.

Then, when entering the power saving mode, the microcomputer 106 controls the clock generator 100 in steps 500 and 504 to change the frequency of the driving clock SCLK to the first braking frequency and from the output of the comparator 108 to the spindle. Check the rotational speed of the motor 104. At this time, if the rotational speed of the spindle motor 104 is lowered to the head lowering speed, the microcomputer 106 changes the frequency of the drive clock SCLK to the second braking frequency in step 506. Accordingly, as shown in FIG. 6, the rotational speed of the spindle motor 104 drops from t0 to 1500 RPM of t1 according to the first braking frequency and then drops from t2 to 500 RPM according to the second braking frequency. FIG. 6 shows a speed down state of the spindle motor 104 when the spindle motor 104 is switched to the power saving mode at time t0 in the state in which the spindle motor 104 rotates at 5400 RPM at constant speed. The normal speed is 5400 RPM and the head descends. For example, the speed is 1500 RPM and the minimum response speed is 500 RPM.

After changing the frequency of the driving clock SCLK to the braking frequency in step 506, the microcomputer 106 checks the rotational speed of the spindle motor 104 from the output of the comparator 108 in steps 508 to 510. do. At this time, if the rotational speed of the spindle motor 104 drops to 500 RPM, which is the lowest response speed, as in time t2 of FIG. 6, after turning off the spindle motor driver 102 as in the usual case in step 512, the power saving is completed. Perform the mode. The spindle motor 104 then stops completely at time t3 in FIG. That is, as described above, since the time when the rotational speed of the spindle motor 104 becomes about 1500 RPM is the time when the head descends, the rotational speed of the spindle motor 104 is rapidly lowered to 1500 RPM while the head moves to the parking area. After lowering the minimum response speed, the spindle motor driver 102 is disabled.

Therefore, by lowering the rotational speed of the spindle motor 104 to the head lowering speed first and then to the frequency corresponding to the lowest response speed, the spindle motor 104 can be stopped quickly even when the torque of the spindle motor 104 is large. do.

In the above description, specific embodiments have been described, but various modifications can be made without departing from the scope of the present invention. In particular, in the embodiment of the present invention has been illustrated that the frequency of the drive clock is lowered once or twice when the power saving mode, the frequency of the drive clock may be lowered step by step more times if necessary. And the two embodiments of the present invention described above may be selected and applied according to the spindle motor employed in the disk drive.

As described above, the present invention has an advantage of minimizing damage to the head and the disk by quickly stopping the spindle motor even in the power saving mode.

Claims (5)

In the spindle motor braking circuit of the disk drive employing the CSS method, A clock generator for generating a driving clock having one of a normal frequency and a lower braking frequency; A spindle motor driver for driving the spindle motor by inputting the drive clock and applying a drive signal having a period corresponding to the frequency thereof to the spindle motor; During the normal mode, the clock generator controls the clock generator to generate the driving clock at the normal frequency, and when the power saving mode is switched to, the rotation speed of the spindle motor corresponds to the braking frequency after changing the driving clock to the braking frequency. And a control unit for disabling the spindle motor driver when the speed is reached. The spindle motor braking circuit of claim 1, wherein the braking frequency is set to a frequency corresponding to the lowest response speed of the spindle motor. In the method for controlling the braking of the spindle motor driven by the spindle motor driver in the disk drive employing the CSS method, Changing the frequency of the drive clock applied to the spindle motor driver to a braking frequency set lower than the normal frequency when the spindle motor is switched to the power saving mode during the normal rotation; And disabling the spindle motor driver when the spindle motor reaches a speed corresponding to the braking frequency. 4. The method of claim 3, wherein the braking frequency is set to a frequency corresponding to the lowest response speed of the spindle motor. In the method for controlling the braking of the spindle motor driven by the spindle motor driver in the disk drive employing the CSS method, Changing a frequency of a driving clock applied to the spindle motor driver to a first braking frequency corresponding to a head falling speed of the disk drive when the spindle motor is switched to a power saving mode while the spindle motor is in normal rotation; Thereafter, when the rotational speed of the spindle motor becomes the head lowering speed, changing the frequency of the driving clock to a second braking frequency corresponding to the lowest response speed of the spindle motor; And then disabling the spindle motor driver when the rotational speed of the spindle motor reaches the minimum response speed.