Abstract:
The invention relates to an information recording apparatus including a head that is disposed so as to face a recording medium, and records information in the recording medium and/or reproduces information therefrom, and a head actuator for moving the head toward and away from the recording medium. The apparatus further comprises a capacitor electrically charged by a power source; and a driving processor for driving the head actuator with electric charge accumulated in the capacitor in accordance with a voltage of the power source, and for retracting the head to a position away from the recording medium.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an apparatus for recording information and a method for retracting the head, in particular, an information recording apparatus for recording and/or reproducing by moving the head with respect to a recording medium, and a method for retracting the head.  
           [0003]    2. Description of the Prior Art  
           [0004]    In prior art optomagnetic disk devices, a distance between an object lens and a disk at the focused position, that is, a working distance of approx. 1 mm has been secured. Therefore, the distance had comparatively sufficient allowance, wherein since a stopper mechanism could be provided between the object lens and the disk, it was possible to physically prevent both of these from being brought into contact with each other. Therefore, it was not necessary for the object lens to be retracted from the disk to a position separated therefrom.  
           [0005]    [0005]FIG. 1 is a perspective view showing one example of a movable head of a prior art optical disk device, and FIG. 2 is a sectional view showing one example of a movable head of a prior art optical disk device.  
           [0006]    The movable head  200  is caused to be movable in the directions of the arrows B-B′, that is, in the diametrical directions of an optical disk  202  by a voice coil motor  201 .  
           [0007]    The movable head  200  is composed so as to include a lens holder  203 , a plate spring  204 , a focus coil  205 , an object lens  206 , an erect mirror  207 , a movable head body  208 , and a permanent magnet  209 . The object lens  206  is fixed on the lens holder  203 . Also, the lens holder  203  is fixed on the movable head body  208  via the plate spring  204  and is caused to be swingable in the directions of the arrows A-A′ with respect to the movable head body  208 . The focus coil  205  is attached to the side of the lens holder  203 . The permanent magnet  209  is fixed on the side of the movable head body  208 , which faces the focus coil  205 .  
           [0008]    As a drive current is caused to flow into the focus coil  205 , a current flowing in the focus coil  205  and a magnetic field that is generated by the permanent magnet  209  interact with each other, wherein a force is generated at the focus coil  205 , and it is possible to cause the lens holder  203  to sway in the directions of the arrows A-A′ by an electromagnetic force acting on the focus coil  205 . Since the lens holder  203  is caused to sway in the directions of the arrows A-A′, the object lens  206  is accordingly caused to sway in the directions of the arrows A-A′, thereby enabling focusing.  
           [0009]    Also, the erect mirror  207  is disposed under the object lens  206  of the movable head body  208  and is fixed on the movable head body  208 . A light beam L is made incident from a fixed head (not illustrated) into the erect mirror  207 . The erect mirror  207  reflects the light beam L input from the fixed head to the direction of the object lens  206 , that is, to the direction of the arrow A. The light beam L reflected by the erect mirror  207  is provided into the object lens  206 . The object lens  206  converges the light beam L from the erect mirror  207  and provides the same to the optical disk  202 .  
           [0010]    The light beam L that is provided into the optical disk  202  is reflected by the optical disk  202 , and is provided to the erect mirror  207  through the object lens  206  again. The erect mirror  207  reflects the light beam L input from the object lens  206  to the direction of the fixed head, that is, the direction of the arrow B.  
           [0011]    At this time, in order to prevent the object lens  206  and the disk  202  from colliding with each other due to an impact applied from the outside, a stopper mechanism  210  that controls movement of the lens holder  203  in the direction of the arrow A is provided.  
           [0012]    In order to provide the stopper mechanism  210 , it is generally necessary to secure a working distance d of 0.5 mm or the like in the worst case to absorb a dimensional error of components and an assembling error of the apparatus. However, recently, it has been requested that the diameter of the light beam L be made smaller in line with an increase in the recording density of the disk  202 . In order to achieve a smaller diameter of the light beam L, it is necessary that the working distance d be made smaller. However, as the working distance d becomes smaller, there may caused a possibility for the disk  202  and the object lens  206  to collide with each other due to a facial swaying of the disk  202 .  
           [0013]    Therefore, without depending on the stopper mechanism  210 , it is necessary to provide a mechanism for retracting the object lens  206  by using auxiliary power.  
           [0014]    As a method for retracting the object lens  206  by using auxiliary power without depending on the stopper mechanism  210 , some methods have been taken into consideration, one of which is a method for employing a battery driven by a chemical reaction as auxiliary power for retraction, and the other of which is a method for employing a back electromotive force of a motor due to inertia rotations of a disk as auxiliary power as in Japanese Unexamined Patent Application No. 1992-32029.  
           [0015]    However, the life cycle of charging and discharging is shortened to be several hundred times where, in order to secure retraction power, a battery employing chemical reaction such as a lithium ion battery is provided. Also, there is another problem in that a longer period of time is required to charge the battery. Therefore, it is unsuitable to use a battery employing chemical reaction as power for retraction of an optical disk device.  
           [0016]    Further, as in Japanese Unexamined Patent Application 1992-32029, in the method for utilizing a back electromotive force of a motor, which is induced by inertia rotations of a disk, as power for retraction, voltage that can be picked up depends on the number of revolutions of the disk. That is, although a high voltage can be picked up where the disk is rotating at a high speed, only a low voltage can be obtained where the disk is rotating at a low speed, wherein another problem arises in that sufficient power for retraction cannot be provided to an actuator.  
           [0017]    Usually, since the surface of the disk is not completely flat but is distorted in the range of several tens of micrometers to several hundreds of micrometers, the lens actuator always repeats up and down movements and focuses with respect to the rotating disk. Therefore, unless a sufficient retraction current is caused to flow, there is a danger that the lens may be brought into collision with the disk due to inertia. Also, where an impact is provided from the outside during the retraction, an adequate acceleration rate is not provided to stand against the impact, and there may be a danger of a collision.  
         SUMMARY OF THE INVENTION  
         [0018]    The present invention was developed in view of the above-described and other situations, and it is therefore an object of the invention to provide an apparatus for recording and/or reproducing information, and a method for retracting the head, and a circuit for retracting the head, by which the head can be securely retracted from a recording medium.  
           [0019]    The present invention is characterized in that electric power is accumulated in a capacitor, and a head actuator for moving and retracting the head is drived by the power accumulated in the capacitor.  
           [0020]    According to the invention, since the head is retracted by the electric power accumulated in the capacitor, the charging and control thereof can be further facilitated with a chemical battery as a secondary battery, and sufficient durability can be secured with respect to repeated charging and discharging of the battery. Further, it is possible to securely retract the head without depending on the status of the charging system.  
           [0021]    Also, the invention is characterized in that a first head actuator for moving the head in the direction toward a recording medium is driven by electric power accumulated in a capacitor, and a second head actuator for moving the head in parallel to the plane or surface of the recording medium is driven with a delay of a designated duration of time.  
           [0022]    According to the invention, since a retraction action is carried out by the second haed actuator for moving the head in the direction along which a recording medium extends with delay after the retraction action of the first head actuator for moving the head in the direction toward the recording medium, when trouble occurs, the first head actuator is first driven with maximum power that can be applied by a capacitor, and the head can be quickly separated from the recording medium.  
           [0023]    The invention is characterized in that the capacitor is an electric double-layer capacitor.  
           [0024]    According to the invention, since the electric double-layer capacitor has a large capacity, it is possible to apply sufficient power to the head actuator with respect to a retraction action.  
           [0025]    As described above, according to the present invention, since the head is retracted by the electric power accumulated in the capacitor, the charging and control thereof can be further facilitated with a chemical battery as a secondary battery, and sufficient durability can be secured with respect to repeated charging and discharging of the battery. Further, the invention has a feature in that it is possible to securely retract the head without depending on the status of the charging system.  
           [0026]    Also, according to the invention, since a retraction action is carried out by the second head actuator for moving the head in the direction along which a recording medium extends with delay after the retraction action of the first head actuator for moving the head in the direction toward the recording medium, when trouble occurs, the first head actuator is first driven with maximum power that can be applied by a capacitor, and the head can be quickly separated from the recording medium. Therefore, the invention has a feature in that it is possible to securely prevent the head from being brought into collision with a recording medium.  
           [0027]    Still further, according to the invention, since the electric double-layer capacitor has a large capacity, it is possible to apply sufficient power to the first head actuator with respect to a retraction action. Therefore, the invention has a feature in that the head can be securely retracted. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    [0028]FIG. 1 is a perspective view of one example of an optical pickup of a prior art optical disk apparatus;  
         [0029]    [0029]FIG. 2 is a sectional view of one example of the optical pickup of the prior art optical disk apparatus;  
         [0030]    [0030]FIG. 3 is a block configurational view of one embodiment of an optical disk apparatus according to the present invention;  
         [0031]    [0031]FIG. 4 is a block configurational view of a retraction circuit  23  of FIG. 3;  
         [0032]    [0032]FIG. 5 is a block configurational view of a control circuit  54  of FIG. 4; and  
         [0033]    [0033]FIG. 6 is a view describing a retraction action of the retraction circuit  23  of FIG. 3. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0034]    [0034]FIG. 3 shows a block configuration of one embodiment of an optical disk apparatus according to the present invention.  
         [0035]    An optical disk apparatus  1  according to the present embodiment is mainly composed of a control unit  2  and a disk enclosure  3 . Also, since the configuration of the head is roughly the same as that of a prior art head shown in FIG. 1 and FIG. 2, description thereof is omitted. However, in the present embodiment, a stopper mechanism  210  is no longer required.  
         [0036]    The control unit  2  is constructed so as to include an interface  11 , a buffer memory  12 , a micro-processing unit (MPU)  13 , an optical disk controller  14 , a READ/WRITE channel  15 , a digital signal processor (DSP)  16 , a focus error signal detecting circuit  17 , a tracking error signal detecting circuit  18 , a zero cross detecting circuit  19 , drivers  20  through  22 , and a retraction circuit  23 . Also, the enclosure  3  is constructed so as to include a laser diode unit  31 , an ID/MO signal detector  32 , a head amplifier  33 , a temperature sensor  34 , a spindle motor  35 , a magnetic head  36 , a multi-division detector  37 , a focus actuator  38 , and a voice coil motor  39 .  
         [0037]    In addition, the focus actuator  38  corresponds to the first moving means, and is composed of a focus coil  205  and a permanent magnet  209 , which are shown in FIG. 1 and FIG. 2.  
         [0038]    The interface  11  of the control unit  2  is used to secure interface with an upper-graded device, and the buffer memory  12  is used to buffer data that are received and transmitted with respect to the upper-graded device. The MPU  13  is used to control the entire action.  
         [0039]    The optical disk controller  14  controls the READ/WRITE channel  15 . The READ/WRITE channel  15  modulates WRITE data and demodulates READ data.  
         [0040]    The laser diode unit  31  emits laser light. Light that is emitted from the laser diode unit  31  is irradiated onto an optical disk, passing through an optical system.  
         [0041]    The light irradiated onto the optical disk is reflected from the optical disk and is provided to the ID/MO signal detector  32  and the multi-division detector  37 . The ID/MO signal detector  32  detects the ID/MO signal components from the light reflected from the optical disk, and provides the detected ID/MO signals to the head amplifiers  33 . The head amplifier  33  amplifies the ID/MO signals and provides the same to the READ/WRITE channel  15 . The READ/WRITE channel  15  demodulates control information and data from the ID/MO signals. The data that are demodulated by the READ/WRITE channel  15  are stored in the buffer memory  12 .  
         [0042]    The multi-division detector  37  is divided into an area for detecting focus error signals and an area for detecting tracking error signals. Signals that are detected by the area for detecting focus error signals of the multi-division detector  37  are provided into the focus error signal detecting circuit  17 , and the focus error signal detecting circuit  17  generates focus error signals on the basis of the detection signals from the area for detecting focus error signals of the multi-division detector  37 .  
         [0043]    The focus error signals that are generated by the focus error signal detecting circuit  17  are provided into the DSP  16 . The DSP  16  generates focus servo signals on the basis of the focus error signals that have been generated by the focus error detecting circuit  17 , and provides the same to the retraction circuit  23 . The retraction circuit  23  corresponds to retracting means described in the Claims, and the retraction circuit  23  provides focus servo signals from the DSP  16  to the driver  22  in normal operations, and carries out a changeover operation so that, when any trouble occurs, a retraction signal for retracting the object lens is provided to the driver  22 . Also, a detailed description is given later of the retraction circuit  23 .  
         [0044]    The driver  22  provides, in normal operations, a drive current to the focus actuator  38  on the basis of the focus servo signals that are provided from the DSP  16  through the retraction circuit  23 . The focus actuator  38  causes the object lens to move in the focusing direction, that is, the directions of the arrows A-A′ shown in FIG. 1 and FIG. 2, on the basis of the drive current from the driver  22 . Since the object lens is moved in the focusing direction, light emitted from the laser diode unit  31  is focused on an optical disk. In addition, when the drive current is provided from the driver  22  on the basis of a retraction signal from the retraction circuit, the focus actuator  38  causes the lens holder  203  to move in a direction of separating from the optical disk, that is, the direction of the arrow A showed in FIG. 1 and FIG. 2, and causes the object lens  206  to be retracted to a position separated from the optical disk.  
         [0045]    Further, the detection signal that is detected by the area for detecting a tracking error signal of the multi-division detector  37  is provided to the tracking error signal detecting circuit  18 . The tracking error signal detecting circuit  18  generates a tracking error signal on the basis of the detection signal from the area for detecting a tracking error signal of the multi-division detector  37 . The tracking error signal that is detected by the tracking error signal circuit  18  is provided to the DSP  16  and the tracking zero cross signal detecting circuit  19 . The DSP  16  generates a tracking error signal or a voice coil motor control signal on the basis of a seek signal and provides the same to the retraction circuit  23 . In normal operations, the retraction circuit  23  provides the voice coil motor control signal from the DSP  16  to the driver  22 , and, in abnormal operations, carries out a changeover operation so that a retraction signal to retract the carriage is provided to the driver  22 . Also, a detailed description is given later of the retraction circuit  23 .  
         [0046]    The driver  22  provides a drive current to the voice coil motor  39  on the basis of the voice coil motor control signal from the retraction circuit  23  or a retraction signal therefrom. The voice coil motor  39  is a positioner that concurrently operates as a seek control actuator and a tracking control actuator, which is driven on the basis of the drive current from the driver  22 , wherein the head is caused to move in the radius direction of an optical disk, that is, the cross direction of tracking or the directions of the arrows B-B′ shown in FIG. 1 and FIG. 2, and seek control and tracking control or retraction control are carried out. In addition, the voice coil motor  39  causes the movable head  200  to move to the end portion in either of the direction of the arrow B or the direction of the arrow B, that is, the retraction position when a drive current is provided from the driver  22  by the retraction signal from the retraction circuit  23 .  
         [0047]    Also, the MPU  13  generates a spindle motor control signal on the basis of the ID/MO signal that is reproduced from the optical disk, and provides the same to the driver  22  through the DSP  16 . The driver  22  causes the spindle motor  35  to turn on the basis of the spindle motor control signal from the DSP  16 .  
         [0048]    Also, a temperature detecting signal from the temperature sensor  34  is provided to the MPU  13  through the DSP  16 . The temperature sensor  34  detects the temperature in the disk enclosure  3 . The MPU  13  generates a bias magnetic field control signal on the basis of the temperature detection signal from the temperature sensor  34 , and provides the same to the driver  21  via the DSP  16 . The driver  21  provides a current to the magnetic head  36  on the basis of the bias magnetic field control signal from the MPU  13 . The magnetic head  36  generates a magnetic field on the basis of the current from the driver  21 . At this time, the bias magnetic field is controlled in response to the temperature detected by the temperature sensor  34 , thereby enabling the optimal READ/WRITE.  
         [0049]    A detailed description is given below of the retraction circuit  23 .  
         [0050]    [0050]FIG. 4 is a block configurational view of the retraction circuit  23 .  
         [0051]    The retraction circuit  23  includes a capacitor  51 , a diode  52 , a voltage follower circuit  53 , a control circuit  54 , analog switches  55  through  60 , and a resistor R 1 . Also, the retraction circuit  23  has input terminals Tin 1  through Tin 5 , a grounding terminal Tgnd, and output terminals Tout 1  through Tout 4 . A mute signal from the DSP  16  is provided to the input terminal Tin 1  that is connected to the output terminal Tout 1  via the analog switch  55 .  
         [0052]    A focus servo signal is provided from the DSP  16  to the input terminal Tin 2 . The input terminal Tin 2  is connected to the output terminal Tout 2  via the analog switch  57 .  
         [0053]    A voice coil motor control signal is provided from the DSP  16  to the input terminal Tin 3 . The input terminal Tin 3  is connected to the output terminal Tout 3  via the analog switch  59 .  
         [0054]    A reference voltage that is generated by a reference voltage generating circuit (not illustrated) is provided into the input terminal Tin 4 . The reference voltage that has been provided to the input terminal Tin 4  is further provided to the control circuit  54 .  
         [0055]    A drive power source voltage is applied from the power circuit  24  to the input terminal Tin 5 . The drive power source voltage provided to the input terminal Tin 5  is provided to the output terminal Tout 4  and to one end of the capacitor  51  via the diode  52 . The output terminal Tout 4  is connected to the driver  22 , thereby providing a drive current to the driver  22 .  
         [0056]    The grounding terminal Tgnd is grounded outside the retraction circuit  23 , wherein the other end of the capacitor  51  is connected to the grounding terminal Tgnd inside the retraction circuit  23 .  
         [0057]    The capacitor  51  is composed of, for example, an electric double-layer capacitor. The electric double-layer capacitor is capable of storing 0.1 F (Farads) even in a small size and storing a remarkably large electric charge equivalent to several thousands of Farads. The electric double-layer capacitor is featured in that charging thereof is enabled in several seconds since there is no accompanying chemical reaction as in normal capacitors, and charging and discharging are made possible with almost no limitation. Also, a detailed framework and types of the electric double-layer capacitor are described in “Electric double-layer capacitor and electricity accumulation system” prepared by Michio Okamura and issued by Nikkan Kogyo Shimbunsha.  
         [0058]    One end of the capacitor  51  is connected to the power source terminal Tin 5  via the output terminal Tout 4  and diode  52 . The power source terminal Tin 5  is connected to the power source circuit  24 . A power source voltage is applied from the power source circuit  24  to the power source terminal Tin 5 .  
         [0059]    The power source voltage applied to the power source terminal Tin 5  is applied to one end of the capacitor and the output terminal Tout 4  via the diode  52 . The capacitor  51  is charged by the power source voltage that is applied from the power source terminal Tin 5  via the diode  52 . The diode  52  is connected so that the direction from the power source terminal Tin 5  toward the capacitor  51  becomes a forward direction, wherein, when the power source voltage applied to the power source terminal Tin 5  is lowered, the electric charge in the capacitor  51  is prevented from an inverted flow to the power source circuit  24 .  
         [0060]    When the voltage applied from the power source circuit  24  to the power source terminal Tin 5  is lowered by cutoff of power source, the electric charge accumulated in the capacitor  51  is provided to the terminal Tout 4  and voltage follower circuit  53 . The voltage follower circuit  53  outputs an output signal responsive to the voltage at one end of the capacitor  51 . The output signal of the voltage follower circuit  53  is provided to the control circuit  54  and analog switches  56 ,  58  and  60 .  
         [0061]    The control circuit  54  switches the analog switches  55  through  60  on the basis of comparison results of the output signals of the voltage follower circuit  53  with the reference voltage that is provided to the input terminal Tin 4 .  
         [0062]    [0062]FIG. 5 is a configurational view of the control circuit  54 .  
         [0063]    The control circuit  54  includes input circuits  61  and  62 , a comparator  63 , a NOT circuit  64  and a delay circuit  65 . An output signal of the voltage follower circuit  53  is provided from the input terminal Tin  11  to the input circuit  61 . The input circuit  61  is composed of a resistor R 11  and a resistor R 12 , and the output signal of the voltage follower circuit  53  is divided in terms of voltage by the resistors R 11  and R 12  and is provided to a non-inverting input terminal of comparator  63 .  
         [0064]    The reference voltage from the input terminal Tin 4  is provided to the input circuit  62  by the input terminal Tin 12 . The input circuit  62  is composed of resistors R 13  and R 14 , wherein the reference voltage is divided by the resistors R 13  and R 14  and is provided to the inverting input terminal of comparator  63 .  
         [0065]    The comparator  63  compares the output voltage of the input circuit  61  with the output voltage of the input circuit  62 . When the output voltage of the input circuit  61  becomes larger than that of the input circuit  62 , the comparator  63  makes the output HIGH. And, the comparator  63  makes the output LOW when the output voltage of the input circuit  61  is lower than that of the input circuit  62 , that is, when the voltage at one end of the capacitor  51  is made lower than an appointed voltage. The output of the comparator  63  is made HIGH when the output voltage of the power source circuit  24  is larger than an appointed voltage and is made LOW when the output voltage of the power source circuit  24  is smaller than the appointed voltage and when the voltage at one end of the capacitor  51  is made smaller than the appointed voltage. Also, the outputs of the comparator  63  are provided to the output terminals Tout 11  through Tout 13  and the NOT circuit  64 .  
         [0066]    The NOT circuit  64  is composed of resistors R 15  and R 16  and a transistor Q 11 . The NOT circuit  64  is driven by voltage of the input terminal Tin 11  and inverts the output of the comparator  63 . The output of the NOT circuit  64  is provided to output terminals Tout 21  and Tout 22 , and is further provided to an output terminal Tout 23  via the delay circuit  65 .  
         [0067]    The delay circuit  65  is composed of a resistor R 17  and a capacitor C 11 , and the same delay circuit  65  delays the output of the NOT circuit  64  by time responsive to a time constant that is determined by the resistor R 17  and capacitor C 11 , and provides the same output to the output terminal Tout 23 .  
         [0068]    The output terminal Tout 11  of the control circuit  54  is connected to a switching control terminal of the analog switch  55 . The output terminal Tout 12  of the control circuit  54  is connected to the switching control terminal of the analog switch  57 . The output terminal Tout 13  of the control circuit  54  is connected to the switching control terminal of the analog switch  59 . The analog switches  55 ,  57  and  59  are turned on when the output terminals Tout 11  through Tout 13 , respectively, of the control circuit  54  are HIGH, and are turned off when these are LOW.  
         [0069]    Further, an output terminal Tout 21  of the control circuit  54  is connected to the switching control terminal of the analog switch  56 . An output terminal Tout 22  of the control circuit  54  is connected to the switching control terminal of the analog switch  58 . An output terminal Tout 23  of the control circuit  54  is connected to the switching control terminal of the analog switch  60 . The analog switches  56  and  58  are turned on when the output terminals Tout 21  and Tout 23 , respectively, of the control circuit  54  are HIGH, and are turned off when these are LOW. The analog switch  60  is turned on in an appointed duration of time after the control terminal Tout 23  becomes HIGH.  
         [0070]    Next, a description is given of operations of the retraction circuit  23 .  
         [0071]    [0071]FIG. 6 is a view describing the operations of the retraction circuit  23 .  
         [0072]    When the power source voltage from the power source circuit  24  is a normal voltage, the control circuit  54  turns on the analog switches  55 ,  57  and  59  and turns off the analog switches  56 ,  58  and  60 . Since the analog switches  55 ,  57  and  59  are turned on and the analog switches  56 ,  58  and  60  are turned off, a mute signal that is provided to the input terminal Tin 1  is provided to the output terminal Tout 1 , the focus servo signal that is provided to the input terminal Tin 2  is provided to the output terminal Tout 2 , and the voice coil motor control signal that is provided to the input terminal Tin 3  is provided to the output terminal Tout 3 .  
         [0073]    The output terminals Tout 1  through Tout 3  are connected to the driver  22 , wherein the mute signal, focus servo signal and voice coil motor control signal are provided to the driver  22 . The driver  22  controls a focus actuator  38  by the focus servo signal from the DSP  16  and controls a voice coil motor  39  by the voice coil motor control signal from the DSP  16 . In addition, the operations of the driver  22  are controlled by the mute signal from the DSP  16 .  
         [0074]    As the power source voltage from the power source circuit  24  drops at time t 1  and becomes lower than an appointed voltage, the control circuit  54  turns off the analog switches  55 ,  57  and  59 , and turns on the analog switches  56  and  58 , whereby an output signal of the voltage follower circuit  53  is provided to the driver  22  as a mute signal and a focus servo signal. A muting action of the driver  22  is cancelled by an output signal of the voltage follower circuit  53 . Also, since the muting action is cancelled in the driver  22 , the focus actuator  38  is driven by an output signal of the voltage follower circuit  53 , and a retraction action in the focusing direction is carried out.  
         [0075]    Further, as the time is delayed by the delay circuit  65  by an appointed duration of time at time t 2 , the analog switch  60  is turned on. When the analog switch  60  is turned on, an output signal of the voltage follower circuit  53  is provided into the driver  22 . The driver  22  drives the voice coil motor  39  by the output signal of the voltage follower circuit  53 . The voice coil motor  39  is driven in the outer circumferential direction of a disk by the output signal of the voltage follower circuit  53 , wherein the movable head  200  is retracted to the outer circumferential portion. In addition, the movable head  200  is moved to the outer circumference of a disk in the present embodiment. However, since there is no facial sway on the inner circumferential side of a disk and there is no fear that the disk is brought into contact with the head, the movable head  200  may be retracted toward the inner circumferential side. Furthermore, a locking mechanism may be provided, which locks the movable head  200  at its retracted position, regardless of the outer circumferential side or the inner circumferential side, wherein, since the movable head  200  is locked at its retracted position by the locking mechanism after the retraction, it is possible to securely prevent the object lens from being brought into collision with a recording medium.  
         [0076]    As described above, by employing an electric double-layer capacitor for the capacitor  51  that provides power to drive the retraction circuit  23 , it is possible to provide a retraction circuit that can be used with almost no limitation with a short preparation time, and can permit a sufficient retraction current to flow.  
         [0077]    Also, by carrying out a retraction action by both the focus actuator  38  and voice coil motor  39  when retracting the head, not only is it possible to prevent the object lens from being instantaneously subjected to a collision with an optical disk, which may occur when the power is interrupted, but also the movable head  20  can be retracted to a safe position. Next, it is possible to prevent the object lens from being brought into contact with an optical disk due to an impact from the outside until power is supplied.  
         [0078]    Further, since the timing of retracting the voice coil motor  39  is delayed when carrying out a retraction action, power is totally concentrated at the focus actuator  38  to cause the lens to be radically separated from an optical disk, and next, the power is supplied to the voice coil motor  39  to move the movable head  200  to a safe position, wherein even if a facial sway of an optical disk occurs and an impact is applied from the outside, it is possible to prevent the object lens from being brought into contact with an optical disk, and a safe retraction action can be carried out.  
         [0079]    Still further, in the present embodiment, although the focus actuator  38  and voice coil motor  39  are driven through the driver  22 , these may be directly driven by electric charge accumulated in the capacitor  51 . For example, the capacitor  51  is connected to the coil  205  of the focus actuator  38  when a retraction action is carried out, and electric charge accumulated in the capacitor  51  is provided to the coil  205  directly or via a current-limiting resistor, etc., thereby retracting the object lens  206 . By carrying out operations similar thereto with respect to the voice coil motor  39 , a retraction action in the tracking direction may be carried out.  
         [0080]    Also, in a drive in which a recording medium is removable, if power is unexpectedly interrupted during operation, a voltage drop will be caused due to consumption of battery charge when being driven by the battery, whereby the recording medium may be left in the drive. In this state, the recording medium is maintained in a position opposed to the object lens. Therefore, the recording medium may be brought into collision with the object lens due to an impact and/or vibrations from the outside, wherein there may be a fear that the object lens is damaged. In particular, in a proximity recording and reproduction type drive in which the distance between a recording medium and the object lens becomes 1 mm or less, it is considered that a recording medium is frequently brought into contact with the object lens. Also, in a case where a user intentionally switches off the power source, or a user moves the drive in which a recording medium is left in the drive, the recording medium may be brought into collision with the object lens since these are subjected to vibrations.  
         [0081]    In the present invention, retraction control is enabled, including the above-described case, and it is possible to prevent the object lens from being brought into collision with a recording medium. Therefore, an example according to the present embodiment becomes particularly effective with respect to a proximity recording/reproduction type drive in which the interval between the object lens and a recording medium becomes 1 mm or less.  
         [0082]    Also, in the embodiment, a description is given of the case of an optical disk apparatus. However, the present embodiment is not limited to an optical disk apparatus, but may be effectively applied to an information recording apparatus, employing an optical head, such as an optical card, optical tape, etc.