Abstract:
There is provided a thin optical disk device having a slot-in mechanism which is able to smoothly carry out operations of clamping and releasing an optical disk. The optical disk device includes an optical pickup which carries out at least either of writing or reading data into or out of the optical disk, a turntable which places the optical disk at an operating position of the optical pickup and rotates the optical disk, a damper which is arranged at an approximate center of the turntable and can freely advance and retreat in a direction of a diameter of the optical disk, and means for clamping an inside diameter section of the optical disk at a location directly above the clamper with the optical disk being held by sandwiching the optical disk and for pressing the inside diameter section from the side of a non-writing surface of the optical disk and clamping the inside diameter section to the clamper.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an optical disk device, and particularly to a clamp mechanism of an optical disk.  
           [0003]    2. Description of the Related Art  
           [0004]    Heretofore, an optical disk device which drives an optical disk, such as a CD, a CD-ROM, or a DVD has adopted a slot-in mechanism in which when the optical disk is inserted through a disk insertion opening, the optical disk is carried to a write or read position by means of a carrier mechanism.  
           [0005]    In this slot-in mechanism, after the optical disk is carried to a prescribed position, a turntable rises and the optical disk is placed on the turntable. After that, the turntable rises further and a clamper which has been waiting above the turntable sticks to the turntable due to magnetic force of a magnet in the turntable. As a result, the optical disk can be sandwiched between the turntable and the clamper.  
           [0006]    However, such a constitution has a problem that it is difficult to make the optical disk device thin because it is necessary to arrange the damper above the turntable.  
           [0007]    Also, a large force is required when clamping of the optical disk is released because clamping is performed by magnetic force, which means that the load on a motor increases.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention aims to provide a thin device which is able to smoothly carry out operations of clamping and releasing an optical disk.  
           [0009]    An optical disk device according to the present invention includes:  
           [0010]    an optical pickup which carries out at least either of writing or reading of data to or from of an optical disk;  
           [0011]    a turntable which places the optical disk at an operating position of the optical pickup and rotates the optical disk;  
           [0012]    a damper which is arranged at an approximate center of the turntable and can freely advance and retreat in a direction of a diameter of the optical disk; and  
           [0013]    means for clamping an inside diameter section of the optical disk at a location directly above the damper with the optical disk being held by sandwiching the optical disk and for pressing the inside diameter section from the side of a non-writing surface of the optical disk and clamping the inside diameter section to the clamper.  
           [0014]    According to the present invention, when the optical disk is clamped to the turntable, the optical disk is shifted and clamped to the damper of the turntable. At this time, the inside diameter section of the optical disk is positioned at a location directly above the damper and the inside diameter section is pressed from the non-writing surface side so as to clamp the inside diameter section to the clamper, as a result of which the optical disk can easily and securely be clamped.  
           [0015]    According to an embodiment of the present invention, the clamping means described above tilts a surface of the optical disk toward a surface of the turntable after bringing the surface of the optical disk into contact with the turntable, and then the clamping means clamps the inside diameter section of the optical disk to the clamper.  
           [0016]    For example, the clamping means sandwiches a part of an outer circumferential section of the optical disk, brings the inside diameter section of the optical disk into contact with the clamper, and presses the sandwiched part, whereby the optical disk is tilted with the inside diameter section as a fulcrum.  
           [0017]    Further, according to another embodiment, the clamping means has retaining means for retaining a semicircular portion of the optical disk and shifting means for moving the optical disk toward the turntable with the optical disk being retained by the retaining means.  
           [0018]    Further, according to yet another embodiment, the retaining means, in a state of retaining a semicircular portion of the optical disk, tilts the side of the semicircular portion of the optical disk in advance of other parts by pressing the inside diameter section of the optical disk to the clamper.  
           [0019]    Further, according to yet another embodiment, the retaining means moves the optical disk using the shifting means and brings the optical disk into contact with the damper while retaining the optical disk in an inclined state.  
           [0020]    Further, according to yet another embodiment, the retaining means is composed of an upper tray and a lower tray which sandwich the semicircular portion of the optical disk.  
           [0021]    Further, according to yet another embodiment, in order to hold an outer circumferential section, at least either of the upper tray or the lower tray opens and closes with the outer circumferential section side as a fulcrum.  
           [0022]    Further, according to yet another embodiment, at least the upper tray is indented in a conical shape at an area corresponding to the central side of the optical disk so as to hold the outer circumferential section of the optical disk.  
           [0023]    Further, according to yet another embodiment, the upper tray has a projection which comes into contact with the inside diameter section and applies pressure on the inside diameter section when the upper tray holds the optical disk.  
           [0024]    As described above, by clamping the optical disk in a state where a surface of the optical disk is not made parallel to a surface of the turntable, but the surface of the optical disk is tilted, among the inside diameter sections of the optical disk, an inside diameter section on the tilted side is first engaged with the clamper provided approximately at a center of the turntable and the optical disk is clamped. Thus, positions of the optical disk and the clamper of the turntable are regulated, whereby the remaining inside diameter section of the optical disk can be easily engaged with the damper and clamping can be executed with a relatively weak force.  
           [0025]    Further, in order to clamp the tilted optical disk, it is necessary only to carry out a clamping operation by sandwiching the semicircular portion of the optical disk and not by sandwiching the entire circumferential portion. By sandwiching only the semicircular portion, the optical disk is tilted towards the clamper of the turntable due to the rigidity of the optical disk. Needless to say, it is also possible to tilt the optical disk by applying force to a third point in a direction perpendicular to the surface of the optical disk while supporting the optical disk by two points which are opposite to each other at an angle of 180 degrees.  
           [0026]    It should be noted that while the present invention will be understood more clearly with reference to the preferred embodiment as will be described below, the scope of the present invention is not limited to the following embodiment. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]    These and other objects of the invention will be explained in the description below, in connection with the accompanying drawings, in which:  
         [0028]    [0028]FIG. 1 is a plan view showing an initial state of an optical disk device.  
         [0029]    [0029]FIG. 2 is a front view of FIG. 1.  
         [0030]    [0030]FIG. 3A is an explanatory drawing showing operation of an upper tray and a lower tray at the time of holding an optical disk having a large diameter.  
         [0031]    [0031]FIG. 3B is an explanatory drawing showing operation of an upper tray and a lower tray at the time of holding an optical disk having a small diameter.  
         [0032]    [0032]FIG. 4 is a plan view (No. 1) showing operation of stuffing an optical disk.  
         [0033]    [0033]FIG. 5 is a longitudinal sectional view of FIG. 4.  
         [0034]    [0034]FIG. 6 is a plan view (NO. 2) showing operation of stuffing an optical disk.  
         [0035]    [0035]FIG. 7 is a longitudinal sectional view of FIG. 6.  
         [0036]    [0036]FIG. 8 is a plan view (No. 3) showing operation of stuffing an optical disk.  
         [0037]    [0037]FIG. 9 is a longitudinal sectional view of FIG. 8.  
         [0038]    [0038]FIG. 10 is a plan view (No. 1) showing a state at the time of clamping an optical disk.  
         [0039]    [0039]FIG. 11 is a longitudinal sectional view of FIG. 10.  
         [0040]    [0040]FIG. 12 is a plan view (No. 2) showing a state at the time of clamping an optical disk.  
         [0041]    [0041]FIG. 13 is a longitudinal sectional view of FIG. 12.  
         [0042]    [0042]FIG. 14A is a block diagram of a lower tray.  
         [0043]    [0043]FIG. 14B is a block diagram of an upper tray.  
         [0044]    [0044]FIG. 14C is a block diagram of an upper tray having a projection.  
         [0045]    [0045]FIG. 15A is an explanatory drawing which shows a positional relationship between an optical disk and a spindle at the time of clamping the optical disk.  
         [0046]    [0046]FIG. 15B is an explanatory drawing showing a positional relationship between an optical disk and a spindle at the time of clamping the optical disk.  
         [0047]    [0047]FIG. 15C is an explanatory drawing showing a positional relationship between an optical disk and a spindle at the time of clamping the optical disk.  
         [0048]    [0048]FIG. 15D is an explanatory drawing showing a positional relationship between an optical disk and a spindle at the time of clamping the optical disk.  
         [0049]    [0049]FIG. 15E is an explanatory drawing showing a positional relationship between an optical disk and a spindle at the time of clamping the optical disk.  
         [0050]    [0050]FIG. 16A is an explanatory drawing showing operation at the time of clamping an optical disk.  
         [0051]    [0051]FIG. 16B is an explanatory drawing showing operation at the time of clamping an optical disk.  
         [0052]    [0052]FIG. 16C is an explanatory drawing showing operation at the time of clamping an optical disk. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0053]    An embodiment of the present invention will now be described based on the accompanying drawings.  
         [0054]    [0054]FIG. 1 shows the constitution of an optical disk device according to this embodiment. An optical disk device  1  has an opening section at its front section and a user inserts an optical disk  100  through the opening section. A pair of arms  10  and  12  are installed at a carrier section  2  of the optical disk device  1 , and pins  10   a  and  12   a  are installed at ends of the arms  10  and  12 ,respectively.  
         [0055]    The arm  10  is connected with the carrier section  2  via an axis  10   b  which is inserted into the carrier section  2  leaving a space between the axis  10   b  and the carrier section  2 . The arm  10  can rotate and move with the axis  10   b  as a center within a plane above the carrier section  2 . The axis  10   b  is arranged in an opening (hole), which is formed at the carrier section  2 , in a state leaving a space between the axis  10   b  and the opening, whereby a position of the arm is defined in a rough manner. Also, with rotation of the arm  10 , the pin  10   a  moves along a groove  11  formed at the carrier section  2 . A range of rotation of the arm  10  is regulated by the groove  11 . Further, the arm  12  is also connected with the carrier section  2  via an axis  12   b  which is inserted into the carrier section  2  leaving a space between the axis  12   b  and the carrier section  2 . The arm  12  can rotate and move with the axis  12   b  as a center within a plane above the carrier section  2 . With rotation of the arm  12 , the pin  12   a  moves along a groove  13  formed at the carrier section  2 . A range of rotation of the arm  12  is regulated by the groove  13 .  
         [0056]    Further, the other end of the arm  10  is connected to a spring  10   c  installed at the carrier section  2 , and when the arm  10  rotates in a direction of an arrow A in FIG. 1 (counterclockwise), the arm  10  rotates against the resilience of the spring  10   c . Therefore, when the arm  10  rotates in a direction of the arrow A in FIG. 1, a restoring force to return the arm  10  to an initial position always acts. The other end of the arm  12  is also connected to a spring  12   c  installed at the carrier section  2 . When the arm  12  rotates in a direction reverse to the direction of the rotation of the arm  10  (clockwise), the arm  12  rotates against the resilience of the spring  12   c  and a restoring force to return the arm  12  to an initial position also acts.  
         [0057]    When a user inserts the optical disk  100  through an opening section at the front, a marginal section of the optical disk  100  comes into contact with the pin  10   a  of the arm  10  and the pin  12   a  of the arm  12 . When the user inserts the optical disk  100  in such a state, the arm  10  and the arm  12  rotate in opposite directions against the resilience of the spring  10   c  and the spring  12   c . Due to the resilience of the spring  10   c  and the spring  12   c , the pin  10   a  and the pin  12   a  are always in contact with the marginal section of the optical disk  100 .  
         [0058]    The carrier section  2  is supported in such a manner that the carrier section  2  can move freely in a direction of an arrow B in FIG. 1 (a vertical direction in the drawing) along a guide groove formed on a side surface of the optical disk device  1 . The carrier section  2  is driven by a driving section composed of a motor and a rack pinion mechanism which are not shown in the drawing. When the optical disk  100  is inserted to a prescribed position, a driving current is applied to the motor and the carrier section  2  carries the optical disk  100  to a write/read position. The carrier section  2  then moves in a direction perpendicular to a paper surface of FIG. 1 (a direction of thickness of the optical disk device 1). The carrier section  2  moves the optical disk  100  downward in a direction of the spindle and clamp the optical disk  100  to the spindle. A further description of operation of clamping the optical disk  100  will be given later.  
         [0059]    Further, a lever  42  is provided at a base section of the optical disk device  1 . One end of the lever  42  is supported by a spring and the other end is in contact with an upper surface of a base  50  by which an optical pickup and a turntable are supported. This lever  42  is bent and its center is supported by an axis in such a manner that the lever  42  can freely oscillate (see FIGS. 16A through 16C). The base  50  is supported by a cushioning material similarly to conventional bases, and when the end of the lever  42  which is supported by the spring is released, the end is urged upward by elasticity of the spring. Thus, the other end of the lever  42  which is in contact with an upper surface of the base  50  is pushed downward and the base  50  is pushed downward against elasticity of the cushioning material (FIG. 16A). Thus, when the carrier section  2  carries the optical disk  100 , the base  50  at which the optical pickup and the turntable are installed retreats downward, thus securing a carrier route.  
         [0060]    [0060]FIG. 2 is a front view showing the optical disk device  1  from a direction of an opening section. An upper tray  14  and a lower tray  16  are installed at the carrier section  2  and the constitution is such that the upper tray  14  and the lower tray  16  sandwich the inserted optical disk  100 . The upper tray  14  and the lower tray  16  sandwich not the entire circumference of the optical disk  100 , but an approximately semicircular portion (a semicircular portion of the optical disk  100  inserted into the carrier section  2 ).  
         [0061]    [0061]FIGS. 3A and 3B typically show the upper tray  14  and the lower tray  16 . The upper tray  14  and the lower tray  16  are not arranged in such a manner that these surfaces are parallel to each other, but are arranged in such a manner that these trays make certain angles with respect to each other. The lower tray  16  is urged by elasticity in a direction of an arrow C in the drawings, namely, in a direction of the upper tray  14 . When the optical disk  100  is inserted, the lower tray  16  is spread out downward against resilience of the lower tray  16 . Thus, the optical disk  100  can be securely sandwiched. Also, the optical disk  100  can be sandwiched with the same constitution whether the optical disk  100  having a diameter of 12 cm is inserted as shown in FIG. 3A or the optical disk  100  having a diameter of 8 cm is inserted as shown in FIG. 3B.  
         [0062]    Operation when the optical disk  100  is inserted into the opening section and pushed to a prescribed position and the carrier section  2  carries the optical disk  100  to the write/read position will now be described step by step.  
         [0063]    &lt;Pushing the Optical Disk&gt; 
         [0064]    [0064]FIG. 4 shows a state where the optical disk  100  is further pushed in from the state shown in FIG. 1. FIG. 5 is a longitudinal sectional view of FIG. 4. When the optical disk  100  is further pushed in from the state shown in FIG. 1, the pin  10   a  and the pin  12   a  which are in contact with the optical disk  100  move along a groove  11  and a groove  13 , respectively. Further, the optical disk  100  comes into contact with a third pin  18  which is located in a groove  20  provided at the carrier section  2 . The third pin  18  is fixed on a pin support plate  19  which is arranged on a rear surface of an upper surface panel of the carrier section  2  via axis  19   a  in such a manner that the pin support plate  19  can move freely. Since the third pin  18  is connected to the carrier section  2  via the pin support plate  19 , reception of the optical disk  100  can be carried out in a stable manner. More specifically, when the optical disk  100  is pushed in further, the third pin  18  moves along the groove  20  and in a short time the third pin  18  comes into contact with one end of the groove  20  (a second stop position) and stops there. Because the third pin  18  comes into contact with the end of the groove  20 , further pushing in of the optical disk  100  is prevented and the position of the contact is defined as a final pushing in position of the optical disk  100 . Incidentally, the above description applies to an optical disk having a diameter of 12 cm. Thus, when an optical disk having a diameter of 8 cm is inserted, the pin  18  comes into contact with the other end of the groove  20  (a first stop position) and stops there. In FIG. 1, an end  21  formed at the groove  20  shows the first stop position and an end  23  shows the second stop position. In consideration of a difference in size between the optical disk having a diameter of 8 cm and the optical disk having a diameter of 12 cm, the second stop position is formed at an inner part relative to the first stop position. Further, a lateral position of the optical disk  100  is regulated by the pin  10   a  and the pin  12   a  located right and left. When the optical disk  100  reaches the final pushing in position, a driving current flows into the motor and the carrier section  2  starts carrying the optical disk  100 .  
         [0065]    The constitution viewed from a side surface and the relationship of the carrier section  2 , the upper tray  14  and the lower tray  16  included in the carrier section  2 , and the optical disk device  1  at the time of pushing in the optical disk  100  will be described with reference to FIG. 5.  
         [0066]    The optical disk  100  is located in the carrier section  2  in such a state that the optical disk  100  is sandwiched by the upper tray  14  and the lower tray  16 . Side surface pins  14   a  and  14   b  (for example, two pieces on each side) which are engaged with guide grooves  21   a  and  21   b  formed on a frame side surface of the optical disk device  1 , via a curved guide groove  2   b  formed at a side plate  2   a  of the carrier section  2 , in such a manner that a space is left between the side surface pins  14   a  and  14   b  and the guide grooves  21   a  and  21   b , respectively, are installed on a side surface of the upper tray  14 . Since the side surface pins  14   a  and  14   b  move under the guidance of the guide groove  2   b  and the guide grooves  21   a  and  21   b , movement of the carrier section  2  and prescribed operation of the upper tray  14  which will be described later are realized. On the other hand, a side surface pin  16   a  (for example, a piece at the front and a piece at the rear) is also formed on a side surface of the lower tray  16 , and the side surface pin  16   a  is engaged with a guide groove  2   c , which is formed in the side plate  2   a  of the carrier section  2 , in such a manner that a space is left between the side surface pin  16   a  and the guide groove  2   c . The guide groove  2   c  is in the shape of a curve so as to guide of rising and falling movement of the lower tray  16 , which will be described later. Incidentally, when the optical disk  100  is pushed in, the side surface pins  14   a  and  14   b  of the upper tray  14  are located at a side end of an opening section of the guide groove  21   a  and at the highest part of the guide groove  2   b . Further, the side surface pin  16   a  of the lower tray  16  is also located at the highest part of the guide groove  2   c.    
         [0067]    &lt;Operation of Carrying the Optical Disk&gt; 
         [0068]    [0068]FIGS. 6 and 7 show operation of the carrier section  2  in the middle of carrying the optical disk  100 . Due to a rack and pinion, the carrier section  2  moves in a direction of the arrow B shown in FIGS. 6 and 7 along the guide grooves  21   a  and  21   b  formed on both of the side surfaces of the optical disk device  1 .  
         [0069]    When the carrier section  2  moves while sandwiching the optical disk  100 , in a short time pins  40  installed at right and left upper ends of the carrier section  2  are engaged with right and left rotators  22  and  24  installed at a base end of the optical disk device  1 . The centers of the right and left rotators  22  and  24  are supported by axes on the base, and a forked claw section is formed at one end of each of the rotators  22  and  24  with the other end being connected with a common arm  32 . Each of the pins  40  comes into contact with either of the forked parts of the claw section. When the carrier section  2  further moves in a direction of the arrow B shown in FIGS. 6 and 7 while the pin is coming into contact with either of the forked parts of the claw section, the rotators  22  and  24  rotate with the axes as the centers. At this time, each of the pins  40  is located between the forked parts of the claw section. As long as the carrier section  2  moves an equal distance on the right and left sides along the guide groove, there is no problem. However, if there is a difference in an amount of movement on the right and left sides, for example if a distance of movement on the right side is longer than a distance of movement on the left side (in the case where the carrier section  2  as a whole leans counterclockwise), the pin  40  of the carrier section  2  first comes into contact with a claw of the rotator  22  on the right side, and the rotator  22  rotates counterclockwise with the fulcrum as the center. Since the rotator  22  and the rotator  24  are connected with each other by the common arm  32  as described above, rotary motion of the rotator  22  is conveyed to the rotator  24  on the left side via the arm  32  and the rotator  24  is caused to rotate clockwise. Due to the rotation of the rotator  24 , the pin  40  on the left side of the carrier section  2  is dragged and a distance of the carrier section&#39;s movement on the left side is increased. The same applies to the case when a distance of the carrier section&#39;s movement on the left side is longer than a distance of the carrier section&#39;s movement on the right side (a case where the carrier section  2  leans clockwise). First, the rotator  24  rotates, interlocking with the rotary motion, the rotator  22  starts rotating, and distances of the carrier section&#39;s movement on the right and left sides are equalized. As shown in FIG. 7, since the carrier section  2  as a whole moves towards the optical disk device  1  at this time, the side surface pins  14   a  and  14   b  of the upper tray  14  only move along the guide grooves  21   a  and  21   b , and the side surface pins  14   a ,  14   b , and  16   a  are left at the highest position of the guide grooves  2   b  and  2   c.    
         [0070]    [0070]FIGS. 8 and 9 show a state where the carrier section  2  has carried the optical disk  100  to the write/read position in the manner described above. When the carrier section  2  carries the optical disk  100  to the write/read position, mobile pieces  25  and  27  installed on the right and left sides of the carrier section  2  come into contact with an end (an upper end in FIG. 8) of the base and the mobile pieces  25  and  27  move in a direction of an arrow D shown in FIG. 8 relative to the carrier section  2 . With respect to the mobile pieces  25  and  27 , pins  25   a  and  27   a  are formed on the surfaces and notch sections  25   b  and  27   b  are formed on the side surfaces. The pins  25   a  and  27   a  are engaged with claws of cams  26  and  28 , which are formed near the arms  10  and  12  of the carrier section  2 , respectively. The notch sections  25   b  and  27   b  are located at upper parts (upper parts in FIG. 8) very close to the locations where the arms  25  and  27  come into contact with the pins  10   a  and  12   a , respectively. The cams  26  and  28  are supported by axes on the carrier section  2  in such a manner that the cams  26  and  28  can rotate freely. When the mobile pieces  25  and  27  move in a direction of the arrow D in FIG. 8, the notch sections  25   b  and  27   b  move to the locations where the arms  25  and  27  come into contact with the pins  10   a  and  12   b . The cam  26  rotates clockwise and the cam  28  rotates counterclockwise. Due to the rotations of the cams  26  and  28 , the cams  26  and  28  are engaged with the arms  10  and  12 , respectively. Thus, the arm  10  is caused to rotate further counterclockwise and the arm  12  is caused to rotate further clockwise. Due to the additional rotations of the arms  10  and  12 , the pins  10   a  and  12   a  which have been in contact with the optical disk  100  additionally move in the grooves  11  and  13 , respectively, and the pins  10   a  and  12   a  separate from the optical disk  100 .  
         [0071]    As shown in FIG. 4, a third cam  30  is supported by an axis on the carrier section  2  and an end of the third cam  30  is in contact with the third pin  18  already described. When the carrier section  2  carries the optical disk  100  to the write/read position, the third cam  30  rotates counterclockwise. Because of this rotation, the third pin  18  is moved to a second position  20   a  in the groove  20 . The third pin  18  also comes into contact with the optical disk  100  at the time of carrying the optical disk  100 , whereby the pushing in position is defined. However, the third pin  18  separates from the optical disk  100  due to the movement of the third pin  18  to the second position  20   a  which is interlocked with the rotation of the cam  30 .  
         [0072]    The above description is related to an optical disk having a diameter of 12 cm. Thus, in the case where an optical disk having a diameter of 8 cm is inserted, the mobile pieces  25  and  27  installed on the right and left sides of the carrier section  2  come into contact with an end (an upper end in FIG. 8) of the base and the mobile pieces  25  and  27  move relatively to the carrier section  2  in a direction of the arrow D in FIG. 8. The pins  25   a  and  27   a  formed on the surfaces of the mobile pieces  25  and  27  are engaged with claws of the cams  26  and  28 , which are formed near the arms  10  and  12  of the carrier section  2 ,respectively. The cam  26  rotates clockwise and the cam  28  rotates counterclockwise. As a result of the rotations, the cams  26  and  28  are engaged with the arms  10  and  12 , respectively, and the arm  10  is caused to move and rotate upward, namely counterclockwise, and the arm  12  is caused to move and rotate upward, namely clockwise. Due to the additional movements and rotations of the arms  10  and  12 , the pins  10   a  and  12   a  which have been in contact with the optical disk  100  make additional movements in the grooves  11  and  13 , respectively, and separate from the optical disk  100 . In the case where an optical disk having a diameter of 8 cm is inserted, an arm  10   d  formed at the arm  10  shown in FIG. 1 also moves and rotates with the additional movement and rotation of the arm  10 . In the case where an optical disk having a diameter of 8 cm is inserted, the third pin  18  in the groove  20  restrains the optical disk having a diameter of 8 cm from being inserted further from a stop position  21 . However, due to the movement and rotation of the arm  10   d  as described above, the arm  10   d  comes into contact with the third pin  18 , and the third pin  18  is caused to move to an escape position  20   b  in the inner part of the groove  20  (a halfway position of the groove  20 ). When the optical disk  100  is carried, the third pin  18  comes into contact with a side surface of the optical disk  100 , whereby a pushing in position of the optical disk  100  is defined. However, by moving to the escape position  20   b , the third pin  18  separates from the optical disk  100  and restraint put on the optical disk  100  is released. Incidentally, FIG. 1 shows a state at the time of inserting an optical disk having a diameter of 12 cm and a position of the third pin  18  is at the time of inserting an optical disk having a diameter of 12 cm.  
         [0073]    In a state of the optical disk  100  as described above (the same for the optical disk having a diameter of 12 cm and the optical disk having a diameter of 8 cm), the side surface pins  14   a  and  14   b  of the upper tray  14  are located at the innermost parts of the guide grooves  21   a  and  21   b  (on the right side in FIG. 9) and carriage of the optical disk  100  in a horizontal direction is completed as shown in FIG. 9. Even in such a state, the side surface pins  14   a ,  14   b , and  16   a  are left at the highest parts of the guide grooves  2   b  and  2   c.    
         [0074]    &lt;Operation of Clamping the Optical Disk&gt; 
         [0075]    [0075]FIGS. 10 through 13 show clamping operation after the optical disk  100  is carried to the write/read position. While the optical disk  100  is sandwiched by the upper tray  14  and the lower tray  16 , the carrier section  2  (at least the upper tray  14  and the lower tray  16 ) moves in a downward direction (in a direction of thickness of the optical disk device  1 ) which is perpendicular to a direction of carriage as shown by an arrow E in FIG. 11. This operation is realized such that the side plate  2   a  of the carrier section  2  moves further in a direction of carriage (in a direction of the arrow B in FIG. 7) and the side surface pins  14   a  and  14   b  move to the lowest part of the guide groove  2   b  along the bent guide groove  2   b  formed at the side plate  2   a  of the bent carrier section  2  in a state where movement in a horizontal direction is restrained by the guide grooves  21   a  and  21   b  which change the directions into a vertical direction at the ends. Incidentally, the side surface pin  16   a  of the lower tray  16  whose movement in a horizontal direction is restrained also moves to the lowest part of the guide groove  2   c  along the guide groove  2   c  with the movement of the side plate  2   a . Due to the downward movement, the inside diameter section of the optical disk  100  is inserted into the clamper of the turntable. A claw or a ball damper which can freely advance and retreat in a direction of the diameter of the optical disk  100  is formed at the damper of the turntable and the inside diameter section of the optical disk  100  is clamped by the claw or the ball clamper.  
         [0076]    Here, since only the semicircular portion of the optical disk  100  is sandwiched by the upper tray  14  and the lower tray  16  in this embodiment, the optical disk  100  is clamped with the optical disk  100  being tilted, making it possible to smoothly carry out clamping operation.  
         [0077]    [0077]FIGS. 14A, 14B, and  14 C show a location where the upper tray  14  and the lower tray  16  sandwich the optical disk  100 . FIG. 14A shows a location of sandwiching the optical disk  100  by the lower tray  16 . FIG. 14B shows a location of sandwiching the optical disk  100  by the upper tray  14 . Both of the upper tray  14  and the lower tray  16  are located only at the upper half of the optical disk  100  and, as shown in FIG. 3A and FIG. 3B, sandwich only the marginal section of the optical disk  100 . If the carrier section  2  moves downward in such a state, the side of the optical disk  100  which is sandwiched by the upper tray  14  and the lower tray  16  will lean downward after the inside diameter section of the optical disk  100  comes into contact with the clamper of the turntable. Incidentally, a surface of the upper tray  14  which is in contact with the optical disk  100  is conical with its center being hollow so that an outer circumferential section of the optical disk  100  can be sandwiched. However, it is possible as a modified example for effectively installing the optical disk  100  at the damper of the turntable, for example, to form a semicircular linear projection  14   c  near an inside diameter of the optical disk  100  on the contact side of the upper tray  14  as shown in FIG. 14C (see FIG. 5). In this case, since a vicinity of the inside diameter of the optical disk  100  can be pressed by the linear projection  14   c  against the clamper of the turntable, it is possible to push in the optical disk  100  to the damper while keeping deflection of the optical disk  100  to a minimum.  
         [0078]    [0078]FIGS. 15A through 15E typically show a state where the optical disk  100  leans at the time of clamping. FIG. 15A shows a state in which the carrier section  2  moves downward and the inside diameter section of the optical disk  100  comes close to a damper  51  of the turntable. FIG. 15B shows a state that the carrier section  2  further moves downward while sandwiching the optical disk  100  and also the inside diameter section of the optical disk  100  comes into contact with a tip of the clamper of the turntable. When the carrier section  2  further moves downward in this state, urging force is applied to the semicircular portion of the optical disk  100  which is sandwiched by the upper tray  14  and the lower tray  16 , whereby the semicircular portion moves downward earlier than a remaining semicircular portion moves. FIG. 15D shows a state where the optical disk  100  leans from the state shown in FIG. 15B due to the urging force. At the tip of the damper  51 , a plurality of claws or ball clampers are installed at symmetrical positions, for example at three symmetrical positions, and elastic support is provided in order for the claws or the ball clampers to withdraw in a direction of the diameter of the optical disk  100  when force is applied. Since the optical disk  100  moves downward while leaning, the semicircular portion on the leaning side is engaged with the claws or the ball dampers easier than the remaining semicircular is. Thus, the inside diameter of the optical disk  100  is first clamped at this portion on the leaning side. FIG. 15E shows a state where a part of the inside diameter section of the optical disk  100  is clamped. Afterwards, if the carrier section  2  makes a further downward movement, the remaining semicircular portion which has not been clamped will be engaged with the claws or the ball dampers and clamped.  
         [0079]    As described above, by inserting the optical disk  100  into the damper  51  of the turntable while sandwiching only the semicircular portion of the optical disk  100 , it is possible to clamp the optical disk  100  while tilting the optical disk  100 . Thus, it is possible to clamp the optical disk  100  with a less powerful force compared with the case where the inside diameter section of the optical disk  100  is simultaneously clamped. Incidentally, FIG. 15C shows such an example where the optical disk  100  has already been tilted before the optical disk  100  comes close to the damper  51 . More specifically, this is an example in which the optical disk  100  is positively tilted when the optical disk  100  is sandwiched by the upper tray  14  and the lower tray  16 , or while the optical disk  100  is coming close to the damper  51  in a state of being sandwiched. Also in this case, after the optical disk  100  comes into contact with the damper  51 , the same state as that of FIG. 15D is brought about.  
         [0080]    After the optical disk  100  is clamped in the manner described above, the upper tray  14  is caused to move upward. More specifically, since the side plate  2   a  of the carrier section  2  moves further in a direction of carriage (in a direction of the arrow B in FIG. 7) as shown in FIG. 13, the side surface pins  14   a  and  14   b  of the upper tray  14  move further along the guide groove  2   b  which is bent upward (see FIG. 5 and the like), whereby the upper tray  14  is caused to move upward. Further, the lower tray  16  is caused to make a further downward movement by operation of the side plate  2   a  similarly and separate from the optical disk  100 . Thus, the optical disk  100  can freely rotate in a state where the optical disk  100  is clamped by the damper of the turntable. FIG. 13 shows a state where clamping by the upper tray  14  and the lower tray  16  is released.  
         [0081]    [0081]FIGS. 16A through 16C more particularly show a sequence of operation of clamping the optical disk  100 . When the optical disk  100  is carried to the write/read position as shown in FIG. 16A, the inside diameter section of the optical disk  100  is located approximately directly above the damper  51  of the turntable. As shown in FIG. 16B, the carrier section  2  moves downward in this state, and the optical disk  100  sandwiched by the upper tray  14  and the lower tray  16  also moves downward and is inserted into the damper  51  of the turntable.  
         [0082]    Further, the other end of the lever  42  moves upward due to oscillation and therefore the base  50  which supports the optical pickup and the turntable moves upward due to elasticity of a cushioning material. It should be noted that a position of the other end of the lever  42  and a position of the base  50  differ in FIG. 16A and FIG. 16B.  
         [0083]    Finally, as shown in FIG. 16C, the upper tray  14  of the carrier section  2  is caused to move upward again and the upper tray  14  which has pressed the optical disk  100  from the above is caused to separate from the optical disk  100 . Further, the lower tray  16  is released from the carrier section  2  and is caused to make a further downward movement contrarily to the carrier section  2  and the lower tray  16  is caused to separate from the optical disk  100 . In a state in FIG. 16C, the inside diameter section of the optical disk  100  is clamped only to the turntable and is not in contact with any of the pins  10   a ,  12   a , and  18  and the upper tray  14  and the lower tray  16 , whereby the optical disk  100  rotates due to the rotation of the turntable and writing/reading is possible.  
         [0084]    Incidentally, according to this embodiment, by moving the optical disk  100  downward while sandwiching a semicircular portion of the optical disk  100 , the optical disk  100  is clamped with the optical disk  100  being tilted. However, it is possible to have a constitution such that when the carrier section  2  moves downward, the optical disk  100  is more positively caused to move downward with the optical disk  100  being held askew and the optical disk  100  is inserted in a tilted state (see FIG. 15C).  
         [0085]    Further, in this embodiment, description of an operation where the optical disk  100  is carried to the write/read position and clamped to the damper of the turntable is given. However, in order to release clamping of the optical disk  100  and carry the optical disk  100  to the initial position, it is merely necessary to perform operation reverse to the operation described above. For example, with respect to release of clamping, the upper tray  14  is moved downward and brought into contact with the optical disk  100  and, at the same time, the lower tray  16  is moved upward and a semicircular portion of the optical disk  100  is sandwiched by the upper tray  14  and the lower tray  16 . The carrier section  2  then moves upward. Since the carrier section  2  moves upward while sandwiching the semicircular portion of the optical disk  100 , the optical disk  100  leans askew, clamping of the semicircular portion sandwiched is first released, and clamping of the remaining semicircular portion is then released. It is possible to easily release clamping by moving the optical disk  100  upward with the optical disk  100  being tilted.  
         [0086]    As described above, according to the present invention, the optical disk can be securely clamped.  
         [0087]    While the preferred embodiment of the present invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the appended claims.