Abstract:
A disc drive arrangement adapted to move a head to a retract position upon shutting down of a power source voltage, wherein the number of retraction actions of the head is counted and notified. With this notification, a user can assume performance deterioration of the disc drive arrangement.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a disc drive apparatus for playing or driving an information recording disc such as a magnetic disc.  
           [0003]    2. Description of the Related Art  
           [0004]    Hard disc drive (HDD) apparatus have prevailed as external memory devices for personal computers, and home-use electric/electronic appliances that have a built-in HDD are also marketed recently because recording density (or memory density) of HDD is improved and price reduction is realized. It is now possible to store a substantial amount of image and music contents in HDD so that products using HDD are manufactured one after another. Such products are expected to be incorporated in automobile audio sets, and it is assumed that most automobile navigation systems will be equipped with HDD although DVD is currently dominant.  
           [0005]    Referring to FIG. 1 of the accompanying drawings, illustrated is a basic structure of HDD. The illustrated HDD is a ramp loading type wherein a magnetic head  51  located at a free end of an actuator  54  is mechanically caused to float from a magnetic disc surface.  
           [0006]    As illustrated, the magnetic head  51  mounted on the actuator  54  is adapted to be able to move in a radial direction of a magnetic disc  53  (as indicated by the double arrow), and be positioned by a voice coil motor (VCM)  160 . The magnetic head  51  is forced on the surface of the magnetic disc  53  with a resilient force of a suspension  57 , but is controlled such that a gap of several tens of micrometers is created between the magnetic head  51  and the magnetic disc surface by an aerodynamic floating force acting on the magnetic head  51  produced upon rotations of the magnetic disc  53 . When not operated, the magnetic head  51  is positioned at a retracted position, at which it rides on a tapered portion  56  of a ramp  55  formed at one end of a housing frame  50 .  
           [0007]    [0007]FIG. 2 is a cross sectional view illustrating positional relationship between the magnetic head  51  and ramp  55 . As shown, the ramp  55  located in the vicinity of an outer periphery of the magnetic disc  53  has the tapered portion  56  that extends in a radially outward direction of the disc. This tapered portion  56  has a gentle inclination extending in a direction apart from the surface of the magnetic disc  53 . The magnetic head  51  is located at a play position (position “a”) above the magnetic disc  53  with a suitable clearance when it reads or writes information out of or into the magnetic disc  53  (i.e., drive condition). When not operated (unload condition), the magnetic head  51  moves over the tapered portion  56  and reaches the shunting position (or stand-by position) “b” as indicated by the arrow A.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0008]    The above described HDD apparatus is equipped with a function called “emergency unload”. The emergency unload function forcibly moves the head to the retract position when a power supply to a motor for driving a spindle  52  and magnetic head  51  fails, in order to prevent the magnetic disc  53  from being damaged by the head. Although a power source is needed to perform the emergency unloading, it is known that when the power supply fails, a counter electromotive force generated by inertia rotations of the spindle motor  52 , i.e., no load electromotive force, can be utilized to carry out the emergency unloading.  
           [0009]    If the above described technique is applied to an engine-driven on-vehicle disc drive apparatus, the emergency unloading operation is executed every time the engine is started up since a battery voltage greatly drops upon starting up of the engine.  
           [0010]    Referring to FIG. 3, illustrated is an example of a power source circuit employed in the engine-driven automobile. Specifically, an alternator G is driven by an engine (not shown). An AC power supplied from the alternator G is rectified and smoothed by a rectifier D and then fed to a battery G. A battery voltage Vb of the battery B is fed to a movable contact “m” of an engine key switch SW. The engine key switch SW has stationary contacts ACC, ON and ST, and the battery voltage Vb passing through the contact ACC is supplied as an ACC power source to a light load LL such as an audio set. The battery voltage Vb passing through the contact ON is supplied as an ON power source to a heavy load HL such as power window. The battery voltage Vb passing through the contact ST is supplied as MST voltage to a starter motor (not shown) to rotate the starter motor and start the engine. The battery voltage Vb is also fed to the light load LL via a line BU as a back-up power source.  
           [0011]    [0011]FIGS. 4A and 4B illustrate voltage changes in the power supply lines in the form of timing charts when the engine is started. Specifically, FIG. 4A illustrates the power source voltage for the back-up power source, and FIG. 4B illustrates the voltage change for the ACC. In these drawings, timing (I), (II), (III) and (IV) correspond to different positions of the engine key switch. Specifically, (I) indicates when the engine key is in the ACC position, which feeds electricity to the light load such as the audio equipments, (II) indicates when the engine key is in the ON position, which feeds electricity to the heavy load such as the power window device, (III) indicates when the engine key is in the ST position, which feeds electricity to the starter motor, and (IV) indicates when the engine key is returned to the ON position.  
           [0012]    In this arrangement, not only the ACC voltage but also the back-up power supply drop in certain occasions because of the battery voltage drop upon starting of the engine (between (III) and (IV) in FIGS. 4A and 4B).  
           [0013]    When, therefore, the above described HDD is employed in an engine-driven vehicle, the emergency unload operation likely takes place every time the engine is started, because of voltage drop upon starting of the engine. Since, as mentioned above, the emergency unloading takes advantage of counter electromotive force of the spindle motor and forcibly causes the head to move, the magnetic head  51  in a product used for a vehicle has more chances to collide against the taper portion  56  of the ramp  55  while it is moving to the shunting position “b” of the ramp  55  than a product such as personal computer used for other than the vehicle. In other words, the ramp  55  and magnetic head  51  in the HDD apparatus used for the vehicle need to have improved durability.  
           [0014]    This is a common problem in the HDD apparatus operated under an unstable power supply.  
           [0015]    The present invention is conceived in view of the above described problems, and has an object to provide a disc drive apparatus that does not have shortened durability even if operated under an unstable power supply.  
           [0016]    In order to solve the above-mentioned problem, there is provided a disc drive apparatus adapted to write and/or read information into and/or from an information recording disc, with the information recording disc being rotated by a rotary drive motor and a head drive being controlled to position a head in a radial direction of the information recording disc under supply of predetermined rated power source voltage, comprising: a forcible restoration device for controlling the head drive to execute a forcible restoration action that forcibly moves the head to a shunting position when the power source voltage drops below a predetermined threshold value; a detection and count device for detecting execution of the forcible restoration action, counting how many times the forcible restoration action is executed, and updating a count value every time execution of the forcible restoration action is detected; and a notification device for notifying an updated count value.  
           [0017]    With the arrangements mentioned above, times of the emergency unloading occurs are monitored and informed to a user through a display, for example, so that the user is notified of an operating condition of a disc drive apparatus and the user&#39;s attention is drawn to when the disc drive apparatus should be replaced and the like. This improves reliability of the disc drive apparatus as a recorded information reproducing apparatus. Even if further, a power supply to the disc drive apparatus is interrupted, it is possible to insure the emergency unloading operation to occur by using a counter electromotive force generated because of inertia rotations of a recording medium and drive means. Moreover, notification and caution to the user is made with different colors depending upon how many times a forced movement occurs so that the user is more effectively notified of when the user should replace the disc drive apparatus and the like. Use of different colors has a greater impact on the user. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a plan view showing a fundamental structure of a ramp-load type HDD;  
         [0019]    [0019]FIG. 2 is a cross sectional view showing positional relationship between a ramp and a head shown in FIG. 1;  
         [0020]    [0020]FIG. 3 illustrates a circuit diagram of power supply lines on vehicle;  
         [0021]    [0021]FIGS. 4A and 4B illustrate timing charts to show an operation sequence of the on-vehicle power sources when an engine is started;  
         [0022]    [0022]FIG. 5 is a block diagram illustrating a car navigation system that incorporates the disc drive apparatus of the present invention;  
         [0023]    [0023]FIG. 6 illustrates a block diagram of HDD, HDC and voltage monitoring circuit shown in FIG. 5;  
         [0024]    [0024]FIGS. 7A and 7B are timing charts showing voltage wave forms of the back-up power source and the ACC power source when the engine is started;.  
         [0025]    [0025]FIGS. 8A and 8B are flowcharts showing an example of operation mode of the disc drive apparatus according to the present invention;  
         [0026]    [0026]FIG. 9 is a flowchart showing another example of operation mode of the disc drive apparatus of the invention; and  
         [0027]    [0027]FIG. 10 depicts an example of a display screen for user notification according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]    Referring to FIG. 5, illustrated is a block diagram of a car navigation system including HDD of the present invention. HDD is used here as a map information storage device of the car navigation system. It should be noted that application of HDD according to the present invention is not limited to the car navigation. The illustrated car navigation system includes a host CPU  11  as its main controller. It also includes ROM  12 , RAM  13 , timer LSI  14 , hard disc apparatus (HDD)  15 , sensor part  16 , GPS receiver  17 , interface  18 , input device  19 , display  20 , display controller  21 , display memory  22 , voice processing circuit  23 , speaker  24 , power supply circuit  25 , hard disc controller (HDC)  26  and buffer RAM  27 .  
         [0029]    The host CPU  11  performs an overall control with respect to navigation such as destination retrieval and route guiding by cooperating with the display controller  21  based on programs stored in ROM  12  and RAM  13  in response to commands from a user supplied from the input device  19 . The host CPU  11  also utilizes geographical information obtained from the sensor  16  and GPS receiver  17  during the control. The timer LSI  14  has a time count value, which is programmable set by the host CPU  11 , and issues interruption upon elapsing of the set time, thereby entrusting the processing to an interruption routine.  
         [0030]    HDC  26  carries out a format control on a magnetic disc loaded into HDD  15 , and also serves as host interface and HDD interface.  
         [0031]    The sensor part  16  represents various sensors needed for the car navigation system to conduct autonomous driving and includes, for instance, a vehicle speed sensor and a gyro-sensor. The sensor part is connected to a system bus  10  via the interface  18 . The interface  18  also receives an output from the GPS receiver  17  so that a hybrid drive control is performed by combination of GPS measured position and autonomous driving.  
         [0032]    The display  20  is a liquid crystal monitor, for example. The display controller  21  writes processed contents such as map information, which is written in the display memory  22  by the host CPU  11 , into the display  20 , and the display  20  shows it on its screen.  
         [0033]    The input device  19  is a remote controller or console, and is used as GUI for inputting commands or talking to the navigation system through the display  20 . The speech processing circuit  23  functions as GUI to issue a voice guide or talk to the navigation system by inputting a voice. The voice guide is output from the speaker  24 . Reference numeral  25  designates a power source circuit to be carried by a vehicle and includes the back-up power supply line “a” and ACC power supply line “b” as described above.  
         [0034]    [0034]FIG. 6 illustrates a voltage monitoring device  30  for detecting a voltage of HDD  15  (FIG. 5) and voltages of the back-up power source and ACC power source of the on-vehicle power source circuit  25 . The on-vehicle power source circuit  25  includes two power sources, one for the back-up power source line  251  and one for the ACC power source line  252 . The voltage monitoring circuit  30  monitors voltage values on the power source lines  251  and  252  supplied from the two power sources mentioned above. A threshold setting circuit  302  has a determined threshold value to detect a voltage drop, and this threshold value is informed to a voltage comparison circuit  301 .  
         [0035]    HDD  15  includes a built-in CPU  152  as its core element, a host interface circuit  151 , a program memory  153 , a data memory  154 , a HDD interface circuit  155 , a R/W (read/write) circuit  156 , a head drive control circuit  157 , a spindle motor control circuit  158 , a magnetic head  51 , a voice coil motor (VCM)  160 , a spindle motor  161  and a counter electromotive force detection circuit  171 .  
         [0036]    The host interface  151 , built-in CPU  152 , program memory  153 , data memory  154  and HDD interface circuit  155  are all connected to an HDD system bus  150 .  
         [0037]    The built-in CPU  152  of HDD receives commands such as Seek, Read/Write, etc. from the host CPU  11  (FIG. 1) through the host interface circuit  151 , and performs the control over the R/W circuit  156 , head drive control circuit  157  and spindle motor control circuit  158  via the HDD interface circuit  155  based on the programs stored in the program memory  153 . Data read from and written into the magnetic disc  53  via the magnetic head  51  is controlled by the R/W circuit  156 . Operations (activation and movements) of VCM  160  are controlled by the head drive control circuit  157 . Rotary movements of the spindle motor  161  are controlled by the spindle motor control circuit  158 . For example, if the back-up power source and ACC power source both drop to 4.5V or less, a counter electromotive force produced by inertia rotations of the spindle motor  161  is fed through a relay contact point rl and line  170 . This is detected and informed to the HDD built-in CPU  152  by a counter electromotive force detection circuit  171 .  
         [0038]    It should be noted that a power supply switch dedicated for HDD may be provided at a position indicated by the broke line rectangle B, for example, upstream of monitor points  251   a  and  252   a  on the lines  251  and  252  of the voltage monitoring circuit  30 .  
         [0039]    [0039]FIG. 7A illustrates a voltage wave of the back-up power source voltage fed through the continuous power supply line  251 , and FIG. 7B illustrates a voltage wave of the ACC power source voltage on the ACC power source line  252 . The threshold value TH is a predetermined voltage value; 9V in this embodiment.  
         [0040]    An operator inserts an engine key into the LOCK position to cancel a lock condition and turns the engine key to the ACC position (time I). This causes the ACC power source to rise and reach, for example, 12V. As the ACC power source voltages rises, electricity is fed to the car navigation system and the spindle motor  161  is activated. Subsequently, the engine key is turned to a start position (time II) via the ON position (time II), to start the engine start motor, whereby the voltages on the back-up power supply line  251  and ACC power supply line  252  both drop. At this point, the emergency unloading takes place in HDD  15 . After a predetermined period, the engine is started, the engine key is returned (time IV), and the voltages of the ACC power supply line  252  and continuous power supply line  251  rise to the initial voltage value 12V, thereby returning to the stable condition. This feeds the power source voltage again to HDD  15  to reactivate HDD  15 . It should be noted that a period from the ACC position to the motor start and that from the motor start to the engine start are random.  
         [0041]    According to the present invention, the number of occurrences of the emergency unloading is monitored and informed to the user. This notifies the user of the operating condition of the disc and calls the user&#39;s attention to replacement of the disc or the like.  
         [0042]    [0042]FIG. 8A illustrates an operation mode of the HDD built-in CPU  152  and FIG. 8B illustrates an operation mode of the host CPU  11 .  
         [0043]    First, it is determined whether the ACC power source is fed to HDD (Step S 31 ). If no electricity is fed, it is then monitored whether a counter electromotive force is generated (Step S 32 ). As described above, the magnetic head  51  is forced to return to the ramp position using the counter electromotive force of the spindle motor  161  during the emergency unloading. Therefore, it is possible to know the occurrence of the emergency unloading from an output of the counter electromotive force detection circuit  171  that detects the generation of the counter electromotive force of the spindle motor  161 .  
         [0044]    When the counter electromotive force is generated, a memory counter associated with the HDD built-in data memory  154  is updated (Step S 33 ) to store the number of occurrences of the emergency unloading.  
         [0045]    In this manner, the HDD built-in CPU  152  always monitors generation of the counter electromotive force while the power is being fed to HDD  15 , so as to store the number of the counter electromotive force generation. On the other hand, as the power is supplied to the car navigation system, the host CPU  11  first issues a read command to HDD  15  (Step S 41 ) and takes the counter value of the memory counter associated with the data memory  154  of HDD  15  to obtain the number of the emergency unloading as data (Step S 42 ) in accordance with a routine shown in FIG. 8B. Then, the host CPU prepares screen data as shown in FIG. 10 and sends it on the display memory  22  (Step S 43 ). The display controller  21  reads the display memory  22  in synchronization with a display timing to indicate the data on the display  20 .  
         [0046]    Thus, the host CPU  11  obtains the number of the emergency unloading ever time the power is supplied to the car navigation system, and commands the displaying on the display unit  20 . It should be noted that the number of the emergency unloading may be displayed upon instructions from a user who operates the input device  19  rather than the occurrences of the power supply to the car navigation system.  
         [0047]    Referring to FIG. 9, illustrated is an example when the system (host CPU  11 ) accumulates and administers the number of the emergency unloading. As described in the foregoing, the emergency unloading occurs when both the ACC power source and back-up power source are shutdown (voltage down). For example, a counter is connected to a non-volatile memory such as the buffer RAM  27  to count how many times the shut down occurs and maintain its count value. By referring to this value upon activation of HDD  15 , the number of the emergency unloading is administered. Specifically, the host CPU  11  first confirms the turning on of the power source of HDD  15  (Step S 51 ). The host CPU  11  then accepts the shut down information from the voltage monitoring circuit  30 . Here, a threshold value for shut down determination is 9V.  
         [0048]    The voltage monitoring circuit  30  shown in FIGS.  5  and  6  always monitors whether both the ACC and back-up power source voltages drop below 9V (Step S 52 ). If they become under 9V, the host CPU  11  updates the accessible counter (buffer RAM  27 ) to count the number of the emergency unloading (Step S 53 ). When the power source-voltage rises beyond 9V and the shut down condition is no longer present (Step S 54 ), then the host CPU refers to the counter value and obtains the number of the emergency unloading as data (Step S 55 ). Subsequently, the host CPU creates the display data as shown in FIG. 10 and transmits it to the display memory  22 . The display controller  21  reads the data from the display memory  22  in synchronization with the display timing such that the data is displayed on the display  20  (Step S 56 ).  
         [0049]    Even if no shut down occurs during the power source voltage monitoring performed by the voltage monitoring circuit  30 , the host CPU  11  refers to the count value to obtain the number of the emergency unloading, creates the display data and transfers it to the display memory  22  for visual indication.  
         [0050]    As described above, the host CPU  11  obtains the number of the power source voltage shut down and outputs a command to the monitor or the like to display it. It should be noted that the number of the shut down, i.e., emergency unloading, may b,e displayed upon a command from the input device  19  operated by the user in addition to upon occurrence of the shut down.  
         [0051]    Referring to FIG. 10, illustrated is an example of a screen used when the number of occurrences of the emergency unloading is monitored and informed to the user according to the present invention. Here, it is entitled “HDD REPORT” and indicated in the form of bar graph at the right corner of the screen of the display  20 . Specifically, the unshaded bar graph is graduated transversely in the number of the emergency unloading (or percentage), and shaded to the right every time the emergency unloading takes place for notification. If the bar graph is divided into three areas colored with green, yellow and read from the left respectively, it provides more effective visual indication for the time of replacement.  
         [0052]    It should be noted that the above described notification may be displayed in a whole screen if necessary upon a request from the user who operates the input device  19  or always displayed at the corner of the screen as shown in the drawing.  
         [0053]    As understood from the foregoing, the present invention can provide a disc drive apparatus that monitors the number of occurrences of the emergency unloading and informs the user of it to let the user know the operating condition of HDD and call the user&#39;s attention to replacement and the like, thereby improving reliability. For example, the number of occurrences of the emergency unloading is indicated to the user through the display so that the user can recognize the operating condition of the disc drive apparatus and know when the user should replace the disc drive apparatus. In addition, the frequency of the forced movements of the disc head is displayed with different colors so that it is possible to notify the user more effectively of the time for replacement of the disc drive apparatus and other information.  
         [0054]    This application is based on a Japanese patent application No. 2000-123262 which is hereby incorporated by reference.