Method of controlling startup current of motor and disk drive using the method

Provided is a method and apparatus for controlling a motor of a disk drive. The method is used to stably control the startup current of a motor by considering a voltage drop and the disk drive uses the method. The method includes managing power-on reset retry information generated during the startup of the motor and determining the startup current of the motor that corresponds to a power-on reset retry count included in the power-on reset retry information.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2004-0090140, filed on Nov. 6, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for controlling a motor of a disk drive, and more particularly, to a method of stably controlling the startup current of a motor in consideration of a voltage drop and a disk drive using the method.

2. Description of the Related Art

U.S. Pat. No. 5,412,809 discloses a circuit and a method for controlling current supplied to a disk drive, which can reduce power consumption associated with the startup of a spindle motor using a micro controller and a memory that stores current versus access time tables. Japanese Patent Laid-Open Publication No. hei 8-275579 discloses a method of driving a spindle motor by supplying power of a predetermined voltage from a power supply unit to a driving signal generating unit, detecting whether a frequency synchronized with the rotation of the spindle motor is within a predetermined range, and varying the driving voltage of the spindle motor if the frequency is outside the predetermined range.

Drives employing a spindle motor include hard disk drives (HDDs), compact disk-read only memory (CD-ROM) drives, digital versatile disk (DVD) drives, and so on. In general, if power is supplied to a disk drive, the disk drive enters an initial mode for starting a spindle motor to rotate a disk. To enable the initially static disk to reach a target rotating speed, much power consumption is required.

Accordingly, the disk drive consumes the most current when initially starting the spindle motor as shown inFIG. 4, and a voltage of power supplied to the disk drive drops due to the excessive current necessary for the initial startup of the spindle motor. If the voltage drops below a predetermined value, stable operation of the disk drive cannot be guaranteed. Accordingly, a power-on reset (POR) signal transits to a logic low level to restart the disk drive, as shown inFIG. 5.

If power supplied to the disk drive is unstable or the resistance of a power line in a printed circuit board (PCB) is large, a greater voltage drop occurs, such that the possibility that the power-on reset signal will transit to a logic low level at the startup of the spindle motor further increases.

Accordingly, if the voltage of power supplied for the startup of the spindle motor drops below a threshold value, the disk drive is repeatedly restarted due to the power-on reset signal, thereby making normal operation of the disk drive impossible.

SUMMARY OF THE INVENTION

The present invention provides a method of controlling the startup current of a spindle motor by detecting whether a power-on reset occurs at the startup of the spindle motor and adaptively varying the startup current of the spindle motor, and a disk drive using the method.

According to an aspect of the present invention, there is provided a method of controlling a motor of a disk drive, the method including: managing power-on reset retry information generated during the startup of the motor; and determining the startup current of the motor that corresponds to a power-on reset count included in the power-on reset retry information.

According to another aspect of the present invention, there is provided a data storage disk drive including: a disk storing information; a motor rotating the disk; a recording medium storing power-on reset retry information; a reset determination unit monitoring a voltage of power and generating a power-on reset control signal if a voltage less than a power-on reset threshold voltage is detected; a controller performing a power-on reset according to the power-on reset control signal, managing the power-on reset retry information stored in predetermined areas of the recording medium, which are not initialized during power-on initialization, and determining the startup current of the motor corresponding to a power-on reset retry count included in the power-on reset retry information; and a driver generating the motor startup current corresponding to the startup current of the motor determined by the controller and supplying the generated motor startup current to the motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below to explain the present invention by referring to the figures. For convenience of explanation, a hard disk drive (HDD) is explained as an example. However, it is clear that a disk drive used in the present invention is not limited to an HDD.

FIG. 1is a top view of an HDD10to which the present invention is applied. The HDD10includes at least one disk12that is rotated by a spindle motor14. The HDD10further includes a transducer16that is located adjacent to a disk surface18.

The transducer16can read or write information on the rotating disk12by detecting a magnetic field of each disk12and magnetizing the disk12. The transducer16is generally associated with the disk surface18. Although the transducer16is illustrated as one body, the transducer16comprises a write transducer for magnetizing the disk12and a separate read transducer for detecting a magnetic field of the disk12. The read transducer consists of a magneto-resistive (MR) element. The transducer16is generally referred to as a head.

The transducer16can be combined with a slider20. The slider20generates an air bearing between the transducer16and the disk surface18, and is incorporated into a head gimbal assembly22. The head gimbal assembly22is attached to an actuator arm24having a voice coil26located adjacent to a magnetic assembly28that specifies a voice coil motor (VCM). Current supplied to the voice coil26generates torque for rotating the actuator arm24about a bearing assembly32. The rotation of the actuator arm24causes the transducer16to move over across the disk surface18.

Information is typically stored in annular tracks34of the disk12. Each of the tracks34generally includes a plurality of sectors, and each of the sectors consists of a data field and an identification field. The identification field includes a gray code that identifies the sector and the track (cylinder). The transducer16moves across the disk surface18to read or write information on other tracks.

FIG. 2is an electrical block diagram of an HDD according to an embodiment of the present invention. As shown inFIG. 2, the HDD includes a reset determination unit201, a controller202, a memory203, a spindle motor driver204, a spindle motor205, a pre-amplifier206, a write/read channel circuit207, an interface circuit208, a VCM driver209, a transducer210, and a voice coil211.

The reset determination unit201monitors the voltage of supplied power, and if the voltage is less than a power-on reset threshold voltage, forcibly moves the transducer210to a parked position and generates a power-on reset control signal to reset the controller202.

Power-on reset retry information is stored at address 0708H to address 070aH of the memory203, and addresses 0708H to 070aH are not initialized during power-on initialization. The power-on reset retry information is composed of power-on reset retry identification data ID and retry count data at the startup of the spindle motor205. The power-on reset retry identification data ID is written in addresses 0708H and 0709H of the memory203, and the retry count data is written in address 070aH.

The pre-amplifier206includes an amplification circuit amplifying a signal detected by the transducer210, a read current control circuit supplying an optimal read current to the transducer210, and a write current control circuit supplying a write current to the transducer210.

The operation of the HDD will now be described. In a data read mode, the pre-amplifier206amplifies an electrical signal detected by the transducer210(i.e., the head) from a disk to enable signal processing afterwards. Thereafter, the write/read channel circuit207encodes the amplified analogue signal into a digital signal that can be decoded by a host device (not shown), converts the digital signal into a data stream, and transfers the data stream to the host device via the interface circuit208.

In a data write mode, the write/read channel circuit207receives data from the host device via the interface circuit208, converts the received data into a binary data stream suitable for a write channel, and then the transducer210writes the data by using the disk write current amplified by the pre-amplifier206.

The controller202controlling the overall operation of the disk drive also controls peripheral circuits to analyze a command received via the interface circuit208and implements the command. The controller202is also coupled to the VCM driver209that supplies a driving current to the voice coil211, and supplies a control signal to the VCM driver209to control excitation of the VCM and the movement of the transducer210.

Further, the controller202manages the power-on reset retry information stored in specific areas of the memory203which are not initialized upon power-on initialization during which power is initially supplied to the disk drive, and determines a startup current to be supplied to the spindle motor corresponding to a retry count included in the power-on reset retry information.

The controller202determines the startup current to be supplied to the spindle motor205as a normal spindle startup current if the power-on reset retry count is “0”, and decreases the startup current of the spindle motor from the normal spindle startup current by a predetermined amount as the power-on reset retry count increases.

In detail, in a power-on initialization mode, referring toFIG. 6A, the controller202performs first, second, and third processes. In the first process, the memory203, except at addresses 0708H to 070aH, is initialized. In the second process, it is determined whether data read from the areas with addresses 0708H and 0709H of the memory203are identical to an initially set power-on reset retry identification data ID (e.g., 55aa and a5a5). If it is determined in the second process that the two data are not identical to the initially set power-on reset retry identification data, in the third process, the power-on reset retry identification data 55aa and a5a5 are written to addresses 0708H and 0709H in the memory203and retry count data “0000” indicating a power-on reset retry count of 0 is written to address 070aH, as shown inFIG. 6B. If it is determined in the second process that the two data are identical to the power-on reset retry identification data, in the third process, the value of the retry count data is increased by one time and written to address 070aH of the memory203.

If the memory203is a non-volatile memory and the spindle motor is successfully started, the controller202writes currently set spindle motor startup current information to addresses of the memory203except addresses 0708H and 0709H, and erases the power-on reset retry information written to address 0708H-0709H of the memory203.

However, if the memory203is a volatile memory and the spindle motor is successfully started, the controller202writes the currently set spindle motor startup current information to of the memory203except addresses 0708H and 0709H.

Next, a method of controlling a spindle motor startup current according to an embodiment of the present invention will be explained with reference to the disk drive ofFIG. 2and the flow chart ofFIG. 3.

If power is supplied to the disk drive, a power-on initialization mode is entered in operation301. In the power-on initialization mode, addresses of the memory except 0708H to 070aH, which are assigned to manage power-on reset retry information as shown inFIG. 6A, are initialized.

Next, in operation302, data D(i) stored in the areas with addresses 0708H and 0709H assigned to store power-on reset retry identification data ID of the memory203are read.

In operation303, the data D(i) read from addresses 0708H and 0709H in the memory203are compared with initially set power-on reset retry identification data ID. If it is determined that the data D(i) read from the areas with addresses 0708H and 0709H of the memory203are not identical to the initially set power-on reset retry identification data ID in operation303, operation304is performed. In operation304, the initially set power-on reset retry identification data ID is written to addresses 0708H and 0709H in the memory203and retry count data “0000” indicating a retry count of 0 RETRY #0 is written to address 070aH of the memory203. Then, in operation S305, the startup current of the spindle motor is determined to be a normal spindle startup current value.

However, if it is determined that the data D(i) read from addresses 0708H and 0709H in the memory203is identical to the initially set power-on reset retry identification data ID in operation303, operation306is performed. In operation S306, the value of retry count data indicating a retry count RETRY # stored in the area with address 070aH in the memory203is read and increased by one. Then, in operation S307, the retry count data increased by one is written to address 070aH in the memory203. The fact that the data stored in addresses 0708H and 0709H are identical to the initially set power-on reset retry information data and the retry count, respectively means that a power-on reset has already occurred at the startup of the spindle motor. That is, if current is excessively consumed at the startup of the spindle motor, the voltage of power drops below a predetermined level due to the excessive current consumption, and thus a power-on reset POR is generated, as indicated inFIG. 5.

Next, in operation308, a spindle startup current corresponding to the retry count data indicating the retry count RETRY # that is written to address 070aH in the memory203is determined again. As the retry count increases, the spindle motor startup current value decreases from the normal spindle startup current value by a predetermined value. After the spindle startup current is determined in operation305or308, operation309is performed. In operation309, the spindle motor is started using the determined spindle startup current.

In operation310, it is determined whether a power-on reset occurs by starting the spindle motor and monitoring whether the voltage of power drops below a power-on reset threshold voltage. If it is determined in operation310that a power-on reset occurs, operation S301is performed and the power-on initialization mode is entered. The fact that the power-on reset occurs means that a large voltage drop has occurred due to a currently set spindle startup current.

If it is determined in operation310that a power-on reset has not occurred and the spindle motor is successfully started, operation311is performed. In operation S311, currently set spindle startup current information is written to addresses of the memory203other than addresses 0708H and 0709H. This is to update the information used to determine the spindle startup current used when the stopped spindle motor is restarted.

Next, if the memory203is a non-volatile memory, such as a flash memory, in operation S312, the power-on reset retry identification data ID stored in the areas with addresses 0708H and 0709H in the memory203is erased. The retry count data stored at address 070aH of the memory203can be erased at the same time. This is because data remains even after power is turned off, and thus the power-on reset retry identification data ID should be erased so that the method of the present invention can be used after the power supply is cut off. However, if the memory203is a volatile memory, operation312can be omitted.

Accordingly, the method of the present embodiment can be used to stably start the spindle motor while reducing the possibility of the repeated occurrence of a repeatedly generated power-on reset by adaptively determining startup current of the spindle motor of the HDD according to the occurrence of a power-on reset and the power-on reset retry count.

External HDDs (2.5″ or less) generally use universal serial bus (USB) power as input power. Here, the USB cannot provide sufficient current in many cases, and a USB cable line is long such that there is a high power-on reset possibility due to voltage drop at the startup of a spindle motor. If the present invention is applied to such external HDDs (2.5″ or less), the repeated occurrence of a power-on reset is prevented during the startup of the spindle motor, and the spindle motor can be stably started.

As described above, according to the present invention, since the spindle startup current of the disk drive is adaptively determined according to the generation of the power-on reset due to a voltage drop, the repeated occurrence of the power-on reset can be prevented and the spindle motor can be stably started.

The invention may be accomplished by a method, an apparatus, a system, and so on. If it is performed by software, constitutional elements of the present invention are code segments that perform essential operations. Programs or code segments can be stored in processor-readable media, and can be sent by computer data signals combined with carrier waves via transmission media or communication networks. The processor readable media include any media that can store or transmit information. Examples of the processor readable media are electronic circuits, semiconductor memory devices, read-only memories (ROMs), erasable ROMs, floppy disks, optical disks, hard disks, optical fiber media, and radio frequency (RF) networks. The computer data signals include any signals that can be transmitted over transmission media, such as electronic network channels, optical fibers, air, electronic systems, and RF networks.