Abstract:
There is provided a method of parking a hard disk drive head, which can minimize an impact during head parking using an alternating current (AC). This method includes the steps of: determining whether no command is input during a predetermined time in a wake-up mode, or whether a power-off command is input; and moving the head to a parking area by driving an actuator to which the head is attached using an initially-set alternating current, if no command was input during the predetermined time or a power-off command was input. Accordingly, damage to the head and head suspension, caused by the collision of the head with a latch magnet because of an excess acceleration of the actuator during parking, can be prevented.

Description:
CLAIM OF PRIORITY 
     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application entitled METHOD FOR PARKING THE HEAD IN HARD DISK DRIVE earlier filed in the Korean Industrial Property Office on the 31th day of December 1998, and there duly assigned Ser. No. 97-82034, a copy of which is annexed hereto. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a method of parking a hard disk drive head, and more particularly to a method of parking a hard disk drive head which can minimize an impact upon parking the head by using an alternating current. 
     2. Related Art 
     In general, a hard disk drive protects data recorded on a disk by fixing its head in a specific position during power off or in a sleep mode. That is, when a user does not operate the hard disk drive for some time, a spindle motor stops rotating the disk, and a voice coil motor moves the head to a parking area allocated close to the center of the disk, to prevent damage to the data if the disk drive suffers an external impact. 
     I have found that disk drive components including the head can be damaged during the parking of the head. Efforts have been made to improve disk drives to prevent such problems. 
     Exemplars of recent efforts in the art include U.S. Pat. No. 5,828,522 for VELOCITY CONTROL OF HEAD LOAD/UNLOAD MECHANISM IN A DISK DRIVE USING DITHER issued to Brown et al., U.S. Pat. No. 5,729,399 for CONTACT START/STOP DISK DRIVE WITH MINIMIZED HEAD-DISK WEAR IN TEXTURED LANDING ZONE issued to Albrecht et al., U.S. Pat. No. 5,663,855 for MAGNETIC LATCHING APPARATUS FOR AN ACTUATOR OF A HARD DISK DRIVE issued to Kim et al., U.S. Pat. No. 5,455,726 for VERSATILE HEAD POSITIONER STOP issued to Liu, U.S. Pat. No. 4,890,176 for CRASH STOP AND MAGNETIC LATCH FOR A VOICE COIL ACTUATOR issued to Casey et al., and U.S. Pat. No. 4,679,102 for METHOD AND MEANS FOR PARKING READ/WRITE HEADS IN A DISC DRIVE USING THE BACK-EMF OF THE SPINDLE MOTOR TO OPERATE A STEPPER MOTOR issued to Wevers et al. 
     While these recent efforts provide advantages, I note that they fail to adequately provide a method of parking a hard disk drive head which efficiently and conveniently prevents damage to disk drive components including the head. 
     SUMMARY OF THE INVENTION 
     To solve the above problems, it is an objective of the present invention to provide a method of parking a hard disk drive head which can reduce impacts to the head and the head suspension during parking. 
     To solve the above problems, it is a further objective of the present invention to provide a method of parking a disk drive head which can reduce impacts to the head and the head suspension during parking, using an alternating current instead of a direct current to park the head of the disk drive. 
     Accordingly, to achieve the above objectives and others, there is provided a method of parking a hard disk drive head, comprising the steps of: determining whether no command is input during a predetermined time in a wake-up mode, or whether a power-off command is input; and moving the head to a parking area by driving an actuator to which the head is attached using an initially-set alternating current, if no command was input during the predetermined time or a power-off command was input. The initially-set alternating current can be a square waveform as an example. 
     To achieve these and other objects in accordance with the principles of the present invention, as embodied and broadly described, the present invention provides a method, comprising: identifying when a predetermined quantity of time elapses, wherein a command signal is not received by a disk drive unit during said predetermined quantity of time; identifying when a power-off command signal is received by said disk drive unit; when said predetermined quantity of time elapses and said command signal is not received by said disk drive unit during said predetermined quantity of time, transporting a head of said disk drive unit to a parking area by driving an actuator coupled to said head using an initially-set alternating current; and when said power-off command signal is received by said disk drive unit, transporting said head of said disk drive unit to said parking area by driving said actuator coupled to said head using said initially-set alternating current. 
     To achieve these and other objects in accordance with the principles of the present invention, as embodied and broadly described, the present invention provides a method, comprising: identifying when a predetermined quantity of time elapses, wherein a command signal is not received by a disk drive unit during said predetermined quantity of time; and when said predetermined quantity of time elapses and said command signal is not received by said disk drive unit during said predetermined quantity of time, transporting a head of said disk drive unit to a parking area by driving an actuator coupled to said head using an initially-set alternating current, said alternating current controlling a speed of said head while said head is transported to said parking area. 
     To achieve these and other objects in accordance with the principles of the present invention, as embodied and broadly described, the present invention provides an apparatus, comprising: a disk having a data area storing first data and a separately located parking area not storing the first data; a transducer reading the first data from and writing the first data to said data area of said disk, said transducer being transported from said data area to said parking area when a power off signal is received, and said transducer being transported from said data area to said parking area when a command signal is not received during a predetermined quantity of time; an actuator being coupled to said transducer; a memory unit storing power data corresponding to a predetermined alternating current; and a control unit being coupled with said memory unit and said actuator, said control unit controlling said actuator by utilizing said alternating current corresponding to said power data, wherein said control unit controls said actuator to perform said transporting of said transducer to said parking area. 
     The present invention is more specifically described in the following paragraphs by reference to the drawings attached only by way of example. Other advantages and features will become apparent from the following description and from the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings, which are incorporated in and constitute a part of this specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below serve to exemplify the principles of this invention. 
     FIG. 1 illustrates the relationship between a voice coil driving current and the speed of an actuator during parking; 
     FIG. 2 illustrates the relationship between a voice coil driving current and the speed of an actuator during parking, in accordance with the principles of the present invention; 
     FIG. 3 is a flowchart illustrating a method of parking a hard disk drive head, in accordance with the principles of the present invention; 
     FIG. 4 is a block diagram illustrating a hard disk drive, in accordance with the principles of the present invention; and 
     FIG. 5 is a block diagram including only blocks associated with the present invention among the blocks shown in FIG. 4, in accordance with the principles of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which a preferred embodiment of the present invention is shown, it is to be understood at the outset of the description which follows that persons of skill in the appropriate arts may modify the invention here described while still achieving the favorable results of this invention. Accordingly, the description which follows is to be understood as being a broad, teaching disclosure directed to persons of skill in the appropriate arts, and not as limiting upon the present invention. 
     A first method of parking a head of a hard disk drive is as follows. When a microprocessor recognizes a power-off mode or a sleep mode, the voice coil motor drives an actuator to which a head is attached, and moves the head to a parking area. That is, a digital-to-analog converter converts a default digital value set in a central processing unit (CPU) to an analog value, and outputs the result to the voice coil motor. Then, the voice coil motor generates a torque using the analog current output from the digital-to-analog converter. This torque moves the head to the parking area. According to the aforementioned first method, a parking current is set as a direct current default value in the central processing unit (CPU) during parking. Thus, the movement speed of the actuator rapidly increases in linear proportion to time, as shown in FIG.  1 . The FIG. 1 shows the relationship between a voice coil driving current and the speed of an actuator during parking. Accordingly, after the actuator is moved to the parking area, it collides with a latch magnet. The head suspension, which holds the head, may be bent due to the impact, particularly upon movement from the outermost circumference to the parking area. This can damage the head and cause defects in in the hard disk drive. 
     Turn now to FIG. 3, which shows a flowchart illustrating a method of parking a hard disk drive head, in accordance with the principles of the present invention. At step  31 , referring to FIG. 3, if a new command is not input for certain time (t) after an already-executed command in a wake-up mode has been input, the time (t) for executing a sleep mode is set, and the driving voltage Vp of a voice coil motor for moving a head to a parking area is set during execution of the sleep mode. The set time and driving voltage are stored in a memory. 
     At step  32 , it is determined whether the hard disk drive is currently in a wake-up mode, that is, not in a sleep mode. At step  33 , after an execution command is input, it is determined whether the time (t c ) for which the next command is input exceeds the time (t) set in the initial value setting step  31 . At step  34 , it is determined whether the input command is a power-off command. At step  35 , the alternating current (AC) parking driving voltage Vp set in step  31  is read from a memory. 
     At step  36 , an actuator to which a head is attached is moved by driving a motor with a voltage (current) corresponding to the alternating current (AC) parking driving voltage (Vp) data read from the memory. 
     FIG. 2 illustrates the relationship between a voice coil driving current and the speed of an actuator during parking, in accordance with the principles of the present invention. FIG. 4 is a block diagram illustrating a hard disk drive, in accordance with the principles of the present invention. FIG. 5 is a block diagram including only blocks associated with the present invention among the blocks shown in FIG. 4, in accordance with the principles of the present invention. 
     The present invention will now be described in detail referring to FIG. 5, based on the flowchart of FIG.  3 . First, the time (t) and the driving voltage (Vp) data of the voice coil motor, which are set in step  31 , are stored at a designated address of a memory  53 . 
     The driving voltage (Vp) data of the voice coil motor must be set to have an alternating current value when it is converted into an analog value. As one embodiment, the driving voltage (Vp) data of the voice coil motor can be set to be a square wave as shown in FIG. 2, when the digital data is converted into an analog value. FIG. 2 illustrates the relationship between a voice coil driving current and the speed of an actuator during parking, in accordance with the principles of the present invention. 
     A controller  51  first determines whether the hard disk drive is in a wake-up mode. That is, it is determined whether the spindle motor rotates, and the head is in a data area for reading/writing, in step  32 . If the hard disk drive is in the wake-up mode, a counter in the controller  51  is reset at the moment when a command is input, and begins counting. Next, the counting value t c  of the counter is compared with the time (t) read from the memory  53 . It is determined whether the counting value t c  of the counter exceeds the time (t) set by the memory  53 , in step  33 . Also, it is determined whether a command input within the time (t) is a power-off command, in step  34 . 
     If the count value t c  of the counter exceeds the time (t), or a command input within the time (t) is a power-off command, then the controller  51  issues a command to a central processing unit (CPU)  52  to read out the driving voltage (Vp) data of the voice coil motor stored in the memory  53  and output the result to a digital-to-analog converter  54 , in step  35 . 
     Then, the digital-to-analog converter  54  converts the input driving voltage value (Vp) data of the digital voice coil motor into an analog value and outputs the result to a voice coil motor (VCM) driving unit  55 . The voice coil motor driving unit  55  moves the head from a data area to a parking area by moving the actuator to which the head is attached, using the input alternating current (AC) driving voltage (Vp) data, in step  36 . 
     Here, the driving voltage Vp of the voice coil motor for parking a head is set as an alternating current (AC) voltage, a square wave as an embodiment, instead of a direct current (DC) voltage in the aforementioned first method, so that the speed of the actuator increases nonlinearly and gently with time as shown in FIG.  2 . The increase of the speed according to time can be appropriately determined by the duty cycle of the square wave. 
     Accordingly, during parking, the actuator to which the head is attached does not move rapidly, so that impact with the latch magnet can be minimized. Therefore, the head suspension can be prevented from being bent by the collision between the actuator and the latch magnet, and damage to the head can be prevented. 
     FIG. 4 shows spindle motor driving unit  413 , an application specific integrated circuit (ASIC)  409 , a central processing unit (CPU)  410 , a voice coil motor (VCM) driving unit  412 , a digital-to-analog (DA)converter  411 , a read only memory (ROM)  415 , a read/write (R/W) unit  403 , a pre-amp  402 , a controller  404 , a buffer-random access memory (buffer-RAM)  405 , and a host computer  407 . The read/write unit  403  is also known as a read/write transducer  403 . The read/write unit  403  is located at the head of the disk drive unit depicted in FIG.  4 . 
     FIG. 4 also depicts a top view of the interior of disk drive  10 . FIG. 4 illustrates an actuator  15 , an arm  20  coupled to the actuator  15 , a head  30  mounted at one end of the arm  20 , a data area storing data, and a parking area where the head  30  can be parked. The head  30  is parked in the parking area when power to the disk drive  10  is turned off. The head  30  is also parked in the parking area when the disk drive  10  is not used during a predetermined period of time. The head  30  writes data to and reads data from the data area depicted in FIG.  4 . The square wave depicted in FIG. 2 can be replaced with a sawtooth wave or a sinusoidal wave or with other alternating current waveforms. 
     According to the present invention as described above, an alternating current (AC) voltage, square wave voltage as an embodiment, instead of a direct current (DC) voltage is set and used as a driving voltage when parking a head, to prevent damage to the head and bending of the head suspension by the collision of the head with the latch magnet because of excess acceleration of the actuator after parking. 
     While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures maybe made from such details without departing from the spirit or scope of the applicant&#39;s general inventive concept.