Abstract:
A method is provided for shifting a rotational speed of a disc. The method includes steps of: detecting a state of a button to determine whether the button is pressed down; counting activating duration if the button is pressed down; determining whether the activating duration is up to a predetermined time; and switching the rotational speed of the disc from a first speed level to a second speed level, if the activating duration is up to a predetermined time. A related disc drive using the method to shift the rotational speed of the disc is also provided.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to disc drives and, more particularly, to a disc drive using a method of shifting rotational speed of a disc. 
       DESCRIPTION OF RELATED ART 
       [0002]    Data discs have become increasingly popular as information storage media due to their vast storage capacity and relatively compact structures. Related disc drives are used to record information on and/or reproduce information from the data discs. Following improvements in storage capacity of the data discs, rotational speeds of the disc drives are also increased. 
         [0003]    A general disc drive includes a spindle motor for driving a disc to rotate. Therefore, a rotational speed of the spindle motor determines a rotational speed of the disc. The disc drive can automatically adjust the rotational speed of the spindle motor during focusing and tracking operations. For example, when reproducing information from the disc, the disc drive drives the spindle motor to rotate at a relatively high speed after startup. Rotation of the spindle motor at the relatively high speed may cause vibration of the disc drive due to reasons such as physical defaults of the disc, thus making it hard for the disc drive to perform focusing and tracking operations. In order to accurately reproduce the information recorded on the disc, the disc drive keeps adjusting the rotational speed of the spindle motor to a relative lower speed until the disc drive can track and focus a target track on a predetermined spot. Therefore, it will cost a relative long time to accurately reproduce the information on the disc. Furthermore, in some instances, the rotation of the spindle motor at relatively high speed may cause unwanted faults. 
         [0004]    Therefore, a method of shifting rotational speed of the disc and a disc drive using the method is desired. 
       SUMMARY OF THE INVENTION 
       [0005]    A method is provided for shifting a rotational speed of a disc. The method includes steps of: detecting a state of a button to determine whether the button is pressed down; counting activating duration if the button is pressed down; determining whether the activating duration is up to a predetermined time; and switching the rotational speed of the disc from a first speed level to a second speed level, if the activating duration is up to a predetermined time. 
         [0006]    A disc drive includes a spindle motor, a servo controller, a button, and a shifting device. The spindle motor is used for driving a disc to rotate. The servo controller is used for controlling a rotational speed of the disc. The shifting device sends shifting commands to the servo controller to shift the rotational speed of the disc from a first level to a second level, if a activating duration during which the button is kept being pressed down is up to a predetermined time. 
         [0007]    A storage medium is provided for recording a computer-executable program. The computer-executable program has a computer execute steps of: detecting a state of a button to determine whether the button is pressed down; counting activating duration if the button is pressed down; determining whether the activating duration is up to a predetermined time; and shifting the rotational speed of the disc from a first speed level to a second speed level, if the activating duration is up to a predetermined time. 
         [0008]    Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Many aspects of the method of shifting a rotational speed of a disc and the disc drive with the method can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disc drive. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0010]      FIG. 1  is an exploded, isometric view of a disc drive; 
           [0011]      FIG. 2  is a block diagram of the disc drive of  FIG. 1 , the disc drive including a shifting device; 
           [0012]      FIG. 3  is a block diagram of the shifting device of  FIG. 1 ; and 
           [0013]      FIG. 4  is a flow chart illustrating a rotational speed shifting procedure in accordance with an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Reference will now be made to the drawings to describe the preferred embodiment of the present method of shifting a rotational speed of a disc and the present disc drive with the present method, in detail. 
         [0015]    Referring to  FIG. 1  and  FIG. 2 , a disc drive  20  that is used for reproducing information recorded on a disc  10 , includes a pick-up unit  210 , a spindle motor  220 , a stepping motor  230 , a control panel  240 , a plurality of functional buttons  250 , an indicating lamp  260 , a servo controller  270 , and a shifting device  280 . 
         [0016]    The pick-up unit  210  is used for emitting a laser beam onto the disc  10  so as to reproduce information recorded on the disc  10  or record information onto the disc  10 . The spindle motor  220  is used for driving the disc  10  to rotate. The stepping motor  230  is used for driving the pick-up unit  210  to move along a radial direction of the disc  10 . 
         [0017]    Usually, the functional buttons  250  include a play button  252  for activating reproducing operations of the disc drive  20 , and an open/close button  254  for activating a movement of a disc tray (not shown) out from or into the disc drive  20 . Any one of the functional buttons  250  may be assigned for activating a shifting of a rotational speed of the disc  10  from a first speed level to a second speed level. The assigned functional button  250  that is used for activating shifting of a rotational speed of the disc  10  is identified as a shifting button. If the play button  252  or the open/close button  254  is chosen as the shifting button, it inherits an original function of activating reproducing operations of the disc drive  20  or activating movement of the disc tray, and further exists an additional function of activating the shifting of the rotational speed of the disc  10 . In order to identify the activation of the original function from an activation of the additional function, the additional function is not activated until the shifting button is applied a force (held down) thereon for a continuous predetermined time. Since the open/close button  254  is prone to cause unexpected movement of the disc tray due to manual operational mistakes, it is better to choose the play button  252  as the shifting button. 
         [0018]    Usually, the indicating lamp  260  is used for indicating working states of the disc drive  20 . In this embodiment, the indicating lamp  260  is also used for indicating by twinkling that a duration of the force applied on the shifting button has lasted for the continuous predetermined time. 
         [0019]    The servo controller  270  is used for controlling rotational speeds of the spindle motor  220  and the stepping motor  230  to perform focusing operations and tracking operations. 
         [0020]    The shifting device  280  is used for determining whether an activating duration during which the force applied on the shifting button reaches the continuous predetermined time. If the activating duration is less than the continuous predetermined time, the original function of the shifting button is performed. The shifting device  280  further controls the indicating lamp  26  to twinkle and sends speed shifting commands to the servo controller  270  so that the servo controller  270  changes the rotational speed of the spindle motor  220  from the first speed level to the second speed level if the activating duration reaches the continuous predetermined time. Accordingly, the rotational speed of the disc  10  is changed corresponding a change of the rotational speed of the spindle motor  220 . 
         [0021]    Referring to  FIG. 3 , the shifting device  280  includes a detecting unit  282 , a timing unit  284 , a controlling unit  285 , a memory unit  286 , and a command-sending unit  288 . 
         [0022]    The detecting unit  282  is used for detecting a state of the shifting button at regular time intervals to determine whether the shifting button is pressed down or released. Such regular time intervals, for example, can be every millisecond. 
         [0023]    The timing unit  284  is used for timing the activating duration during which the shifting button is pressed down. 
         [0024]    The controlling unit  285  is used for controlling working states of the timing unit  284  and the indicating lamp  260  according to the state of the shifting button and the activating duration. When the detecting unit  282  detects that the shifting button is pressed down, the controlling unit  285  controls the timing unit  284  to begin timing the activating duration. When the detecting unit  282  detects that the shifting button is released or that the activating duration reaches the continuous predetermined time, the controlling unit  285  controls the timing unit  284  to stop timing the activating duration. When the activating duration reaches the continuous predetermined time, the controlling unit  285  controls the indicating lamp  260  to twinkle. 
         [0025]    The memory unit  286  is used for storing the continuous predetermined time and the speed levels of the disc  10 . Exemplarily, the continuous predetermined time is three seconds. For any data discs, respective specifications specify a data transfer rate corresponding to a base rotational speed. For example, specifications of compact disc audio (CD_DA) specify that the data transfer rate corresponding to a base rotational speed (so called 1×) is 150 Kbps. Doubling the base rotational speed (so called 2×) would double the data transfer rate. In this embodiment, such speed level may be 1×, 2×, 4×, 6×, 8×, 16×, 32×, or 40×. The number of the speed levels can be ten. That is, the rotational speed of the disc can be shifted among the ten speed levels. 
         [0026]    The command-sending unit  288  is used for sending shifting commands to the servo controller  270  so as to shift the rotational speed of the spindle motor  220  and the disc  10 . 
         [0027]    Referring to  FIG. 4 , a flow chart of a rotational speed shifting procedure is illustrated. First, in step  504 , the detecting unit  282  detects the state of the shifting button to determine whether the shifting button is pressed down. 
         [0028]    If the detecting unit  282  detects that the shifting button is pressed down, in step  506 , the detecting unit  282  informs the controlling unit  285  of the state of the shifting button, and the controlling unit  285  controls the timing unit  284  to begin timing the activating duration. 
         [0029]    Subsequently, in step  508 , the controlling unit  285  determines whether the activating duration reaches the continuous predetermined time. 
         [0030]    If in step  508  the activating duration is concluded to be less than the continuous predetermined time, the detecting unit  282  detects the state of the shifting button to determine whether the shifting button is released (step  510 ). 
         [0031]    If in step  510  the shifting button is concluded to be not released, the procedure goes back to step  508 . If in step  510  the shifting button is concluded to be released, the procedure proceeds to step  512  where the controlling unit  285  controls the timing unit  284  to stop timing the activating duration. Then, in step  514 , the disc drive  20  performs the original function of the shifting button. 
         [0032]    If in step  508 , the activating duration is concluded to reach the predetermined time, the controlling unit  285  controls the timing unit  284  to stop timing the activating duration (step  516 ), and controls the indicating lamp  260  to begin twinkling (step  518 ). 
         [0033]    Then, in step  520 , the detecting unit  282  detects the state of the shifting button to determine whether the functional button is released. 
         [0034]    If the functional button is released, in step  522 , the controlling unit  285  controls the indicating lamp  260  to stop twinkling. 
         [0035]    Subsequently, in step  524 , the command-sending unit  288  sends shifting commands to the servo controller  270  to shift the rotational speed of the disc from the first speed level to the second speed level. After that, the procedure is ended. 
         [0036]    The disc drive  20  allows a user to shift the rotational speed of the disc  10  to a relative low speed during an initialization process of the disc drive  20 . During focusing and tracking process, if it is hard to seek a specific target track and/or focus on a specific spot, rotation of the disc  10  at the relative low speed may help the disc drive to perform focusing and tracking operations in a relatively short time. 
         [0037]    The embodiments described herein are merely illustrative of the principles of the present invention. Other arrangements and advantages may be devised by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, the present invention should be deemed not to be limited to the above detailed description, but rather by the spirit and scope of the claims that follow, and their equivalents.