Abstract:
An optical pickup device comprises an optical pickup body, a lens holder for holding the objective lens, a movable support member connected to the lens holder through a plurality of elongated flexible members for movably supporting the lens holder, a support section provided on the optical pickup body, said support section being arranged substantially perpendicular to an optical disc on which information is to be recorded or from which information is to be read out. In particular, the movable support member is adjustably attached on the support section in such a manner that the position of the objective lens is adjustable.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to an optical pickup device for recording information on an optical disc or for reproducing information from an optical disc.  
           [0002]    A conventional optical pickup device includes a frame structure mounting a light source, a photodetector, and some other optical elements forming an optical path. Installed on the frame structure is a base section mounting an objective lens and a lens driving system.  
           [0003]    When recording information on an optical disc or reproducing information therefrom, a beam light emitted from the light source is directed along the optical path to pass through the objective lens so as to irradiate an information recording surface of an optical disc. Meanwhile, a control means is used to control the movement of the objective lens in both a focus direction and a tracking direction, and a light reflected from the optical disc is also directed to pass through the objective lens so as to be received and detected by the photodetector.  
           [0004]    In order to record or reproduce information correctly, the optical pickup device should be adjusted such that an optical axis of the objective lens is arranged on the optical path in a correct manner. For this reason, such optical device is usually provided with a position adjusting means to adjust the optical axis of an objective lens with respect to an information recording surface of an optical disc.  
           [0005]    [0005]FIG. 9 is a sectional view in side elevation indicating the structure of a position adjusting means provided in a conventional optical pickup device. As shown in FIG. 9, a lens holder  102  on which an objective lens  101  is mounted and fixed, is movably supported by a support section  104  through a plurality of elongate flexible members  103 , in a manner such that the objective lens  101  may be driven in both a focus direction (indicated by an arrow F in FIG. 9) and a tracking direction (perpendicular to the paper of FIG. 9). The support section  104  has an integrally formed protruding portion  104   a  having a partially spherical shape. In detail, the convex portion  104   a  is engaged in a notched recess  105   a  of a frame structure  105  carrying a light source (not shown), a photodetector (not shown), and some other optical elements (not shown) forming an optical path.  
           [0006]    Referring again to FIG. 9, the support section  104  may be adjusted in its position with respect to the frame structure  105 , by driving screws  107  in a clockwise or counterclockwise direction. Then, an adjusted position may be maintained by means of a spring  106  which causes the convex portion  104   a  to be urged against the notched recess  105   a.  In fact, there are two screws  107  formed in pair and disposed in two axial directions. By properly adjusting the pair of screws  107 , the convex portion  104   a  may get tightly engaged in the notched recess  105  with the optical center of the objective lens  101  serving as a central axis. Therefore, it is possible to have the optical axis of the objective lens  101  adjusted in a radial direction (tracking direction) and in a tangential direction (indicated by an arrow T in FIG. 9).  
           [0007]    However, with the conventional optical pickup device shown in FIG. 9, since the convex portion  104   a  is formed on the bottom of the base section  104  right under the objective lens  101 , a sufficient space is needed in the thickness direction (optical axis direction) of the device. As a result, the optical pickup device has to obtain a considerable thickness, rendering it difficult to produce a compact device. Moreover, since two screws  107  are needed to be disposed in two axial directions for adjusting the optical axis of the objective lens in both the radial direction and the tangential direction, it is difficult to reduce the number of necessary parts for forming the optical pickup device, thus. production cost may not be easily lowered.  
         SUMMARY OF THE INVENTION  
         [0008]    It is an object of the present invention to provide an improved optical pickup device having a small thickness and capable of adjusting the position of an objective lens using only a simplified structure, so as to solve the above-mentioned problems peculiar to the above-mentioned prior art.  
           [0009]    According to the present invention, there is provided an improved optical pickup device holding an objective lens in a manner such that the objective lens is movable in both a focus direction and a tracking direction, said optical pickup device comprising: an optical pickup body; a lens holder for holding the objective lens; a movable support member connected to the lens holder through a plurality of elongated flexible members for movably supporting the lens holder; a support section provided on the optical pickup body, said support section being arranged substantially perpendicular to an optical disc on which information is to be recorded or from which information is to be read out. In particular, the movable support member is adjustably attached on the support section in such a manner that the position of the objective lens is adjustable.  
           [0010]    In one aspect of the present invention, the elongated flexible members are linear wires, with one end of each connected to the lens holder and the other end of each to the movable support member, said linear wires being arranged in parallel to the optical disc on which information is to be recorded or from which information is to be read out.  
           [0011]    In another aspect of the present invention, the support section is formed with a restricting groove having a predetermined width and extending in a direction substantially perpendicular to the optical disc, the movable support member is provided with a cylindrical sliding pin engageable and slidable in the restricting groove. Further, the support section has a sliding surface for the movable support member to slide thereon, the movable support member may be moved on the sliding surface so that its position is adjusted to thereby adjust the position of the objective lens. In particular, the sliding surface is a concave spherical surface which is formed by a part of a single spherical surface. Alternatively, the sliding surface is formed by combining several flat surfaces.  
           [0012]    In further aspect of the present invention, the movable support member is formed with a plurality of spherical projections on one surface thereof which will come into contact with the sliding surface. Particularly, the spherical projections are arranged such that the normal line of each spherical projection at a contacting point with the sliding surface, may generally pass through the optical center of the objective lens.  
           [0013]    In still further aspect of the present invention, the position adjustment of the objective lens includes adjusting the optical axis of the objective lens in both a radial direction and a tangential direction, with respect to the information recording surface of an optical disc on which information is to be recorded or from which information is to be read out. The adjustment in the radial direction is performed by rendering the pin to pivot in the restricting groove and rendering the movable support member to move over the sliding surface. The adjustment in the tangential direction is performed by rendering the pin to slide in the restricting groove and rendering the movable support member to move over the sliding surface.  
           [0014]    The above objects and features of the present invention will become better understood from the following description with reference to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0015]    [0015]FIG. 1 is a top plane view indicating an optical pickup device made according to the present invention.  
         [0016]    [0016]FIG. 2 is a sectional view in side elevation indicating the optical pickup device of FIG. 1.  
         [0017]    [0017]FIG. 3 is a perspective view indicating a part of the optical pickup device of FIG. 1.  
         [0018]    [0018]FIG. 4 is a top plane view indicating a condition where the optical pickup device has been attached on an lens position adjustment apparatus.  
         [0019]    [0019]FIG. 5 a  is a side elevation indicating an eccentric driver for use in the lens position adjustment apparatus.  
         [0020]    [0020]FIG. 5 b  is a rear view indicating the eccentric driver of FIG. 5 a.    
         [0021]    [0021]FIGS. 6 a - 6   c  are explanatory views indicating that the position of the movable support member of the optical pickup device may be changed in a radial direction by means of eccentric drivers.  
         [0022]    [0022]FIGS. 7 a - 7   c  are explanatory views indicating that the position of the movable support member of the optical pickup device may be changed in a tangential direction by means of eccentric drivers.  
         [0023]    [0023]FIGS. 8 a - 8   c  are explanatory views indicating that the spherical projections of the movable support member of the optical pickup device may be changed in their positions in a tangential direction by means of eccentric drivers.  
         [0024]    [0024]FIG. 9 is a sectional view in side elevation indicating the structure of an optical pickup device according to a prior art. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    Referring to FIGS. 1 and 2 showing an embodiment of the present invention, an objective lens  1  together with a focus coil and a tracking coil are fixed on a lens holder  2 , in a manner such that the optical axis of the objective lens  1  is perpendicular to the paper of FIG. 1.  
         [0026]    The lens holder  2  is connected with four flexible wires  3  at one end of each. The other end of each flexible wire  3  is connected to a movable support member  4 . In fact, each of the four flexible wires  3  is made of a resin or a metal having a predetermined flexibility. The movable support member  4  serves to flexibly and floatingly support the lens holder  2  (carrying the objective lens  1 ) through the four flexible wires  3 . In detail, the four flexible wires  3  are arranged in parallel in a manner such that the objective lens  1  is movable in both a focus direction (see FIG. 2) and a tracking direction (see FIG. 1).  
         [0027]    A cylindrical pin  4   a  having its central axis coincident with a tangential direction passing through the optical center of the objective lens  1  and perpendicular to the tracking direction, is formed on the movable support member  4  at a position close to the center thereof. Further, spherical projections  4   b,    4   c,    4   d  are formed on the outer surface of the support member  4  along the outer circumference thereof.  
         [0028]    Referring again to FIG. 1, a pair of grooves  4   e,    4   e  are formed on two side surfaces of the movable support member  4 , in a symmetrical relation with respect to the cylindrical pin  4   a.    
         [0029]    The above discussed elements are all mounted on a frame structure  5 . A support portion  5   a  is formed upright on the frame structure  5 , such that it is generally perpendicular to an optical disc  11  on which information recording or reproducing is to be performed.  
         [0030]    [0030]FIG. 3 is a perspective view partially illustrating the frame structure  5  including the support portion  5   a.  In fact, the frame structure  5  is connected through both sides thereof to guide shafts  7  and  8  (see FIGS. 1 and 2) on an information recording/reproducing apparatus. As shown in FIG. 3, the support portion  5   a  is formed by an upright standing portion of the frame structure  5 .  
         [0031]    The support portion  5   a  includes a side wall portion  5   b  arranged lengthwise of the guide shaft  7 . The inner surface of the side wall portion  5   b  is formed with a sliding surface  5   c  (indicated by black portion in FIG. 3). In more detail, the sliding surface  5   c  is formed by a recess portion which is part of a single spherical surface with the optical center of the objective lens  1  as its center. However, the curvature radius of the sliding surface  5   c  is greatly larger than that of each spherical projection  4   b,    4   c  or  4   d.    
         [0032]    Referring again to FIG. 3, a groove  5   d  is formed on the middle of side wall portion  5   b,  in a manner such that the groove  5   d  is arranged in a direction perpendicular to an optical disc  11  mounted in position on the recording/reproducing apparatus. In particular, the groove  5  has a width so formed that when the pin  4   a  is inserted in the groove  5 , the pin  4   a  is allowed to easily pivot or slide therealong.  
         [0033]    Referring further to FIG. 3, a pair of notches  5   e,    5   e  and a pair of through holes  5   f  are formed on opposite side walls arranged in a direction perpendicular to the lengthwise direction of the guide shaft  7 .  
         [0034]    Referring again to FIGS. 1 and 2, what are mounted on the frame structure  5  also includes a magnetic circuit (including a magnet, a yoke, and some other elements) for driving a coil, a leaf spring  6  for pressing the movable support member  4 , a hologram unit  10  (including a light source, a photodetector and a spectroscope), and other optical elements (not shown) for forming an optical path.  
         [0035]    The frame structure  5  is supported horizontally on both sides thereof by guide shafts  7  and  8 , in a manner such that it is movable in the lengthwise direction of the guide shafts  7  and  8 .  
         [0036]    With the pin  4   a  inserted in the groove  5   d,  and with the movable support member  4  being pressed by the leaf spring  6  so that the spherical projections  4   b,    4   c,    4   d  are caused to get in contact with the sliding surface  5   c,  the movable support member  4  may be held in position on the side wall portion  5   b  of the frame structure  5 .  
         [0037]    The recess portion of the sliding surface  5   c  is so formed that the optical center of the objective lens  1  will always be kept at an unchanged position, irrespective of which positions the spherical projections  4   b,    4   c,    4   d  are in contact with the recess portion of the sliding surface  5   c.  In this way, when the movable support member  4  is installed on the side wall portion  5   b  of the frame structure  5 , the center point of a spherical space defined by the sliding surface  5   c  will become substantially coincident with the optical center of the objective lens  1 . Further, the spherical projections  4   b,    4   c,    4   d  are arranged such that the normal line of each spherical projection at a contact point (in contact with the sliding surface  5   c ), may generally pass through the optical center of the objective lens  1 .  
         [0038]    The movable support member  4  installed in the frame structure  5  may be easily adjusted in its position on the side wall portion  5   b,  a leaf spring  6  serves to maintain the movable member  4  at an adjusted position. By adjusting the position of the movable support member  4  in this manner, the position of the optical axis of the objective lens  1  in the tracking direction and tangential direction may be corrected properly, enabling the optical axis of the objective lens  1  to be adjusted so as to be completely coincident with a predetermined optical path.  
         [0039]    The optical pickup device, after having been adjusted in the above manner, shall be connected on both sides thereof to the guide shafts  7  and  8 . Then, as shown in FIG. 2, a beam light is emitted from a light source of the hologram unit  10 , passing through the objective lens  1  along a predetermined optical path, so as to irradiate the information recording surface of an optical disc  11 . A light reflected from the optical disc  11  is also directed to pass through the objective lens  1  so as to be detected by a photodetector. In this way, information recording or information reproducing may be performed on the optical disc  11 .  
         [0040]    The position adjustment of the optical pickup device will be described in more detail below.  
         [0041]    In fact, the position adjustment of the optical pickup device is effected by adjusting the position of the movable support member  4  installed on the side wall portion  5   b  of the frame structure  5 . In more detail, the movable support member  4  flexibly supporting the lens holder  2  (carrying an objective lens  1 ) by means of four flexible wires  3 , is slightly pivoted in the tracking direction (radial direction), so as to correct or adjust the position of the optical axis of the objective lens in the radial direction, thus completing a radial skew adjustment. Further, the position of the movable support member  4  may be changed along the tangential direction, so as to correct or adjust the position of the optical axis of the objective lens  1  in the tangential direction, thus completing a tangential skew adjustment. Since the radial skew adjustment and the tangential skew adjustment may be performed independently, the position of the optical axis of the objective lens  1  in both the radial direction and the tangential direction may be easily adjusted, thereby ensuring that the optical axis of the objective lens  1  is coincident with a predetermined optical path in the optical pickup device.  
         [0042]    In practice, the position adjustment of the optical pickup device may be accomplished with the use of a skew adjustment apparatus shown in FIG. 4.  
         [0043]    [0043]FIG. 4 is a top plane view illustrating a skew adjustment apparatus on which an optical pickup device has been attached. Referring to FIG. 4, the skew adjustment apparatus comprises a base section  12 , a mounting structure  13  provided on the base section  12 , a pair of bearings  14 ,  15  provided on either side of the mounting structure  13 . The mounting structure  13  is adapted to mount the optical pickup device in a horizontal position. Further, a pair of guide shafts  13   a,    13   b  are provided to more exactly keep the optical pickup device in the horizontal position. Then, a screw  16  is used to fix the optical pickup device in the above horizontal position to prevent any undesirable movement.  
         [0044]    On either side of the optical pickup are a pair of adjusting grooves  4   e  and a pair of guide holes of formed on the frame structure  5 . The pair of bearings  14 ,  15  are engaged with the adjusting grooves  4   e  and guide holes  5   f,  so as to rotatably support a pair of eccentric drivers  17 ,  17 .  
         [0045]    [0045]FIG. 5 a  is a side elevation showing each eccentric driver  17 , FIG. 5 b  is a front view of the eccentric driver  17 . As shown in FIG. 5 a,  a pair of cylindrical pins  17   a  and  17   b  are provided in parallel on each eccentric driver  17 , with the pin  17   a  being coincident with the center axis D of the driver  17 .  
         [0046]    In this manner, the pin  17   a  is allowed to rotatably engage in the guide hole  5   f  formed on the side wall  5   a  of the frame structure  5 , the pin  17   b  is allowed to slidably engaged in the adjusting groove  4   e  formed on the movable support member  4 .  
         [0047]    The skew adjustment of an optical pickup device in tangential direction with the use of the above skew adjusting apparatus will be described in detail below.  
         [0048]    Referring to FIG. 4, the tangential skew adjustment may be accomplished by rotating the pair of eccentric drivers  17 ,  17  in the same direction through the same amount of angle so as to have the movable support member  4  inclined properly in the tangential direction.  
         [0049]    In more detail, the eccentric driver  17  on the right is rotated through a certain angle in a direction P, while the eccentric driver  17  on the left is rotated simultaneously through the same angle in a direction R. Thus, both the left and right eccentric drivers  17 ,  17  are simultaneously rotated about the guide holes  5   f  through the same angle, so that each pin  17   b  in engagement with an adjusting groove  4   e  is moved upwardly as viewed in the FIG. 4.  
         [0050]    Each notched recess  5   e  is so formed that the upward movement of each pin  17   b  during the tangential skew adjustment will not be hampered. As a result, each pin  17   b  is allowed to slid in a groove  4   e  so as to upwardly move the movable support member  4 .  
         [0051]    At this time, with the pin  4   a  engaged in the restricting groove  5   d,  the leaf spring  6  acts to push the movable support member  4  so that the spherical projections  4   b,    4   c,    4   d  get in contact with the sliding surface  5   c.  When the movable support member  4  is moved upwardly due to an action of each pin  17   b,  the pin  4   a  is caused to slid vertically along the restricting groove  5 , so that the spherical projections  4   b,    4   c,    4   d  will slid along the sliding surface  5   c.    
         [0052]    At this moment, since the spherical projections  4   b,    4   c,    4   d  are arranged such that the normal line of each spherical projection at a contact point with the sliding surface  5   c,  may generally pass through the optical center of the objective lens  1 , the movement of the movable support member  4  over the sliding surface  5   c  will not cause any change in the position of the optical center of the objective lens  1 .  
         [0053]    Since one pin  17   a  is moved an amount which is the same as that of the other pin  17   a,  the movable support member  4  may be horizontally raised up. Thus, the movable support member  4  is allowed to incline in one direction of the tangential direction without causing any change in the position of the optical axis of the objective lens  1 . As a result, the optical axis of the objective lens  1  may be adjusted in its position in the tangential direction in a desired manner.  
         [0054]    On the other hand, as shown in FIG. 4, the eccentric driver  17  on the right may be rotated through a certain angle in a direction Q, while the eccentric driver  17  on the left may be rotated simultaneously through the same angle in a direction S. Thus, both the left and right eccentric drivers  17  may be simultaneously rotated about the guide holes of through the same angle, so that each pin  17   b  in engagement with an adjusting groove  4   e  is moved downwardly as viewed in the FIG. 4.  
         [0055]    Thus, through operations similar to those discussed above, the optical axis of the objective lens  1  may be inclined in an opposite direction (opposite to the above-mentioned direction) of the tangential direction in a desired manner.  
         [0056]    As discussed above, the tangential skew adjustment may be accomplished by rotating the pair of eccentric drivers  17 ,  17  in the same direction through the same amount of angle so as to have the movable support member  4  adjusted properly in its position in the tangential direction. In practice, such tangential skew adjustment shall be performed until an inclination angle of the optical axis of the objective lens  1  in the tangential direction becomes zero.  
         [0057]    [0057]FIGS. 6 a - 6   c  are cross sectional views indicating that an optical pickup device may be in various different positions when attached on a skew adjustment apparatus, and that the movable support member  4  of the optical pickup device may be pivoted by a pair of eccentric drivers  17 ,  17  to different positions in the tangential direction with respect to the frame structure  5 .  
         [0058]    [0058]FIG. 6 a  indicates a condition where the optical axis L of the objective lens  1  is coincident with a predetermined optical axis Y of the optical pickup device, whilst FIGS. 6 b  and  6   c  indicate conditions where the optical axis L of the objective lens  1  is deviated from a predetermined optical axis Y of the optical pickup device.  
         [0059]    Thus, when the movable support member  4  is located on the side wall portion  5   b  as shown in FIG. 6 b,  the optical axis L of the objective lens  1  may be made coincident with the optical axis Y of the optical pickup device by rotating the right eccentric driver  17  in a direction P and simultaneously rotating the left eccentric driver  17  in a direction R.  
         [0060]    On the other hand, when the movable support member  4  is located on the side wall portion  5   b  as shown in FIG. 6 c,  the optical axis L of the objective lens  1  may be made coincident with the optical axis Y of the optical pickup device by rotating the right eccentric driver  17  in a direction Q and simultaneously rotating the left eccentric driver  17  in a direction S.  
         [0061]    [0061]FIGS. 7 a - 7   c  are explanatory views taken perpendicularly to FIGS. 6 a - 6   c,  indicating various positions of the spherical projections  4   b,    4   c,    4   d  of the movable support member  4  with respect to the frame structure  5 .  
         [0062]    Namely, when the movable support member  4  is located on the side wall portion  5   b  as shown in FIG. 6 b,  the spherical projections  4   b,    4   c,    4   d  will be disposed in a manner as shown in FIG. 7 b.  Thus, by rotating the right eccentric driver  17  in a direction P and simultaneously rotating the left eccentric driver  17  in a direction R, the pin  4   a  will move vertically to an upper position along the groove  5   d,  enabling all the spherical projections  4   b,    4   c,    4   d  to move vertically to upper positions. In this way, a relative relationship between the spherical projections  4   b,    4   c,    4   d  and the frame structure  5  will be like that shown in FIG. 7 a,  rendering an inclination of the optical axis L of the objective lens  1  in the tangential direction to become zero.  
         [0063]    On the other hand, when the movable support member  4  is located on the side wall portion  5   b  as shown in FIG. 6 c,  the spherical projections  4   b,    4   c,    4   d  will be disposed in a manner as shown in FIG. 7 c.  Thus, by rotating the right eccentric driver  17  in a direction Q and simultaneously rotating the left eccentric driver  17  in a direction S, the pin  4   a  will move vertically to a lower position along the groove  5   d,  enabling all the spherical projections  4   b,    4   c,    4   d  to move vertically to lower positions. In this way, a relative relationship between the spherical projections  4   b,    4   c,    4   d  and the frame structure  5  will be like that shown in FIG. 7 a,  rendering an inclination of the optical axis L of the objective lens  1  in the tangential direction to become zero.  
         [0064]    Now, the radial skew adjustment will be described in detail below with reference to FIG. 4. As shown in FIG. 4, when the right eccentric driver  17  is rotated in a direction P and simultaneously the left eccentric driver  17  is rotated in a direction S, the pair of eccentric drivers  17 ,  17  are rotated about the guide holes  5   f  in opposite directions but through the same angle. In this way, the pin  17   b  of the right eccentric driver  17  will move upwardly (as viewed in FIG. 4) along an arc-like path, while the pin  17   b  of the left eccentric driver  17  will move downwardly (as viewed in FIG. 4) along an arc-like path.  
         [0065]    As a result, the pin  17   b  of the right eccentric driver  17  will slid along the groove  4   e  to cause the movable support member  4  to move upwardly. On the other hand, the pin  17   b  of the left eccentric driver  17  will slid along the groove  4   e  to cause the movable support member  4  to move downwardly.  
         [0066]    At this time, with the pin  4   a  engaged in the restricting groove  5   d,  the movable support member  4  is pressed by the leaf spring  6  so that the spherical projections  4   b,    4   c,    4   d  get in contact with the sliding surface  5   c.  Thus, when the pins  17   b  of the two eccentric drivers  17  move, the pin  4   a  engaged in the restricting groove  5   d  will be pivoted in the groove  5   d,  so that the spherical projections  4   b,    4   c,    4   d  are able to slid over the sliding surface  5   c.    
         [0067]    At this moment, since the spherical projections  4   b,    4   c,    4   d  are arranged such that the normal line of each spherical projection at a contact point with the sliding surface  5   c,  may generally pass through the optical center of the objective lens  1 , the movement of the movable support member  4  over the sliding surface  5   c  will not cause any change in the position of the optical center of the objective lens  1 .  
         [0068]    Thus, the movable support member  4  may be adjusted in the radial direction without causing any change in the position of the optical axis of the objective lens  1 . As a result, the optical axis of the objective lens  1  is adjusted in its position in the radial direction in a desired manner.  
         [0069]    On the other hand, as shown in FIG. 4, when the right eccentric driver  17  is rotated in a direction Q and simultaneously the left eccentric driver  17  is rotated in a direction R, the pair of eccentric drivers  17 ,  17  are rotated about the guide holes  5   f  in opposite directions but through the same angle. In this way, the pin  17   b  of the right eccentric driver  17  will move upwardly (as viewed in FIG. 4) along an arc-like path, whilst the pin  17   b  of the left eccentric driver  17  will move downwardly (as viewed in FIG. 4) along an arc-like path.  
         [0070]    Thus, the movable support member  4  is allowed to be adjusted in the radial direction, so that the optical axis of the objective lens  1  may be adjusted in its position in the radial direction.  
         [0071]    Similar to the above tangential skew adjustment, the radial skew adjustment shall also be performed until an inclination angle of the optical axis of the objective lens  1  in the radial direction becomes zero.  
         [0072]    [0072]FIGS. 8 a - 8   c  are explanatory views, indicating that the positions of the spherical projections  4   b,    4   c,    4   d  of the movable support member  4  (of the optical pickup device when mounted on the skew adjustment apparatus shown in FIG. 4) may be changed in the radial direction with respect to the frame structure  5 .  
         [0073]    [0073]FIG. 8 a  indicates a condition where the optical axis L of the objective lens  1  is coincident with a predetermined optical axis Y of the optical pickup device, whilst FIGS. 8 b  and  8   c  indicate conditions where the optical axis L of the objective lens  1  is deviated from a predetermined optical axis Y of the optical pickup device.  
         [0074]    Thus, when the movable support member  4  is located on the side wall portion  5   b  as shown in FIG. 8 b,  the optical axis L of the objective lens  1  may be made coincident with the optical axis Y of the optical pickup device by rotating the right eccentric driver  17  in a direction P and simultaneously rotating the left eccentric driver  17  in a direction S. At this time, the pin  4   a  engaged in the restricting groove  5   d  will be pivoted without having any movement in the vertical direction.  
         [0075]    On the other hand, when the movable support member  4  is located on the side wall portion  5   b  as shown in FIG. 8 c,  the optical axis L of the objective lens  1  may be made coincident with the optical axis Y of the optical pickup device by rotating the right eccentric driver  17  in a direction Q and simultaneously rotating the left eccentric driver  17  in a direction R. Similarly, the pin  4   a  engaged in the restricting groove  5   d  will be pivoted without having any movement in the vertical direction.  
         [0076]    As is understood from the above description, the position adjustment of an optical pickup device may be accomplished by respectively performing the tangential skew adjustment and the radial skew adjustment. Therefore, when an optical pickup device is in a process of being installed in an information recording/reproducing apparatus, the objective lens  1  may be easily and properly adjusted in its position so that the optical axis L of the objective lens  1  may be easily made coincident with the optical axis Y of the optical pickup device.  
         [0077]    While the presently preferred embodiments of the this invention have been shown and described above, it is to be understood that these disclosures are for the purpose of illustration and that various changes and modifications may be made without departing from the scope of the invention as set forth in the appended claims.