Patent Publication Number: US-2003235141-A1

Title: Clearance adjusting screw and beam angle adjusting mechanism

Description:
BACKGROUND OF THE INVENTION  
       [0001] The present invention relates to a clearance adjusting screw for adjusting a clearance between two bodies and a beam angle adjusting mechanism of a disk player, which writes data on an optical disk, e.g., CDs, employing the clearance adjusting screw so as to precisely adjust an angle of a laser beam irradiated from an optical pick-up.  
       [0002] These days, data are written on and stored in optical disks, e.g., CD-Rs, CD-RWs, DVDs. And, disk players capable of writing and reproducing data, e.g., CD-RW players, DVD players, are manufactured. To write data on an optical disk, a power of a laser beam irradiating the optical disk must be maintained prescribed level. Thus, a high power optical pick-up is employed, further it is important to irradiate the laser beam at the right angle with respect to the optical disk.  
       [0003] However, degree of parallel between a turn table, on which the optical disk is mounted, and a chassis, to which the optical pick-up is slidably attached, is not fixed due to machining accuracy of parts, assembling accuracy, etc. Namely, the degree of parallel of disk players usually vary.  
       [0004] To precisely adjust the degree of parallel between the turn table and the chassis, some beam angle adjusting mechanisms for adjusting an angle of a laser beam irradiated from the optical pick-up have been employed in disk players. By the mechanisms, the degree of parallel between the turn table and the chassis or a beam angle of the laser beam with respect to the optical disk can be adjusted when disk players are shipped.  
       [0005] An example of the conventional beam angle adjusting mechanisms is shown in FIGS. 1, 2 and  9 . FIG. 1 is a plan view of a chassis of a generic disk player. FIG. 1 shows a relationship between an optical pick-up attached to a chassis and a turn table, and positions of three connecting points of the beam angle adjusting mechanism. FIG. 2 is a sectional view taken along a line X-X of FIG. 1. FIG. 9 is a sectional view of the conventional beam angle adjusting mechanism taken along a line Y-Y of FIG. 1.  
       [0006] As shown in FIG. 1, a chassis  10  is formed like a plate and fixed in a housing (not shown) of a disk player. A guide rail (not shown) is fixed on the chassis  10   m  and an optical pick-up  12  is moved along the guide rail, so that the optical pick-up  12  can be moved in the radial direction of an optical disk  14 . The guide rail is usually arranged in parallel to the chassis  10 . Therefore, the optical pick-up  12  is moved in a plane parallel to the chassis  10 .  
       [0007] As shown in FIG. 2, a turn table  18  is fixed to an output shaft  16  of a spindle motor  20 . The spindle motor  20  is fixed to a motor plate  22 , and the motor plate  22  is attached to the chassis  10 , so that the spindle motor  20  is attached to the chassis  10 .  
       [0008] An angle of the motor plate  22  with respect to the chassis  10  can be adjusted by an adjusting mechanism  24 . By adjusting the angle of the motor plate  22 , an angle between the turn table  18  and the chassis  10  can be adjusted, so that a beam angle of a laser beam irradiated from the optical pick-up  12 , with respect to the optical disk  14 , can be adjusted.  
       [0009] The mechanism  24  for adjusting the angle of the turn table  18  will be explained with reference to FIG. 9. The mechanism  24  is provided between the motor plate  22  and the chassis  10 . The motor plate  22  and the chassis  10  are mutually connected at three connecting points  26 ,  28  and  30 .  
       [0010] The point  26  acts as a standard connecting point. At the standard connecting point  26 , a clearance between the chassis  10  and the motor plate  22  is fixed, namely the clearance cannot be changed. Other points  28  and  30  act as adjustable connecting points, at which the clearance can be adjusted. By the adjustable connecting points  28  and  30 , the clearance between the motor plate  22  and the chassis  10  at the standard connecting point  26  can be maintained, even if the angle of the motor plate  22  is slightly changed.  
       [0011] For example, a stud  32  is provided between the chassis  10  and the motor plate  22  at the standard connecting point  26  (see FIG. 9). The stud  32  is fixed by a screw  34 , which is inserted from the motor plate  22  side. Further, a ring-shaped elastic member  40  is provided between the stud  32  and the motor plate  22  as a shock absorber.  
       [0012] The clearance between the chassis  10  and the motor plate  22  can be adjusted at the adjustable connecting points  28  and  30 . Note that, the point  30  may be the standard connecting point; the points  26  and  30  may be the adjustable connecting points.  
       [0013] At the adjustable connecting points  28  and  30 , screws  104  are respectively pierced through through-holes  100  bored in the motor plate  22 , and their front end sections are respectively screwed with female screw sections  102  of the chassis  10 . Coil springs  106 , which respectively cover the screws  104 , are elastically provided between the chassis  10  and the motor plate  22 . With this structure, the coil springs  106  always bias the motor plate  22  to move away from the chassis  10 , so that the motor plate  22  contacts flat faces of head sections  104   a  of the screws  104 .  
       [0014] When a worker turns the screws  104  so as to move the motor  22  toward the chassis  10 , the head sections  104   a  push the motor plate  22 , so that the clearance between the chassis  10  and the motor plate  22  is made narrower. On the other hand, when the worker turns the screws  104  in the opposite direction, the head sections  104   a  are moved away from the chassis  10 , so that the motor plate  22  is moved away from the chassis  10 , together with the head sections  104   a , by the coil springs  106 .  
       [0015] By adjusting the clearance between chassis  10  and the motor plate  22  by turning the screw or screws  104  at the adjustable connecting point or points  28  and  30 , the angle of the motor plate  22  with respect to the chassis  10  can be adjusted. Further, inclination of the turn table  18 , which is fixed to the output shaft  16  of the spindle motor  20 , can be adjusted.  
       [0016] However, the coil springs  106  of the adjustable connecting points  28  and  30  can absorb shocks and vibrations applied to the disk player, but the coil springs  106  vary the clearance between the chassis  10  and the motor plate  22 . By the expansion and contraction of the coil springs  106 , it is difficult to maintain the beam angle of the laser beam with respect to the optical disk  14 .  
       [0017] When the disk player is shocked, a part of the coil spring  106  is accidentally engaged with a thread of a male screw section of the screw  104 . If the coil spring  106  is engaged, the coil spring  106  cannot return to an initial position and the motor plate  22  is much inclined with respect to the chassis  10 .  
       [0018] Further, in the case of rotating the optical disk  104  at high speed, the disk player vibrates. The vibration badly influences the coil springs  106 , so that the clearance between the chassis  10  and the motor plate  22  vary. By the variation of the clearance, the beam angle of the laser beam cannot be steadied.  
       SUMMARY OF THE INVENTION  
       [0019] An object of the present invention is to provide a clearance adjusting screw, which is capable of precisely adjusting a clearance between two bodies, and a beam angle adjusting mechanism of a disk player, which is capable of precisely adjusting an angle of a laser beam with respect to an optical disk.  
       [0020] To achieve the object, the clearance adjusting screw, which is capable of adjusting a clearance between a first body and a second body,  
       [0021] comprises:  
       [0022] a first male screw section capable of screwing with a first female screw section of the first body; and  
       [0023] a second male screw section capable of screwing with a second female screw section of the second body,  
       [0024] wherein the first male screw section and the second male screw section are coaxially formed, and  
       [0025] one of the male screw sections is a right-hand screw, and the other male screw section is a left-hand screw.  
       [0026] In the clearance adjusting screw, a diameter of the second male screw section may be shorter than that of the first male screw section,  
       [0027] the second male screw section may be extended from one end of the first male screw section, and  
       [0028] a head section, which contacts the first body, may be provided to the other end of the first male screw section. With this structure, the clearance between the two bodies can be adjusted by inserting the clearance adjusting screw from outside of the first body.  
       [0029] The beam angle adjusting mechanism, which is capable of adjusting an angle of a laser beam irradiated from an optical pick-up of a disk player,  
       [0030] comprises:  
       [0031] a chassis holding the optical pick-up;  
       [0032] a plate holding a spindle motor, in which a turn table for holding an optical disk is attached to an output shaft;  
       [0033] a standard connecting point at which the chassis and the plate are connected and a clearance therebetween is fixed;  
       [0034] at least one adjustable connecting point at which the chassis and the plate are connected and the clearance therebetween can be adjusted; and  
       [0035] a clearance adjusting screw for adjusting the clearance between the chassis and the plate at the adjustable connecting point so as to adjust an angle of the plate with respect to the chassis,  
       [0036] wherein the clearance adjusting screw comprises:  
       [0037] a first male screw section is capable of screwing with a first female screw section of the plate,  
       [0038] a second male screw section is capable of screwing with a second female screw section of the chassis,  
       [0039] the first male screw section and the second male screw section are coaxially formed, and  
       [0040] one of the male screw sections is a right-hand screw, and the other male screw section is a left-hand screw.  
       [0041] Further, the beam angle adjusting mechanism,  
       [0042] comprises:  
       [0043] a plate holding the optical pick-up;  
       [0044] a chassis holding a spindle motor, in which a turn table for holding an optical disk is attached to an output shaft;  
       [0045] a standard connecting point at which the chassis and the plate are connected and a clearance therebetween is fixed;  
       [0046] at least one adjustable connecting point at which the chassis and the plate are connected and the clearance therebetween can be adjusted; and  
       [0047] a clearance adjusting screw for adjusting the clearance between the chassis and the plate at the adjustable connecting point so as to adjust an angle of the plate with respect to the chassis,  
       [0048] wherein the clearance adjusting screw comprises:  
       [0049] a first male screw section is capable of screwing with a first female screw section of the plate,  
       [0050] a second male screw section is capable of screwing with a second female screw section of the chassis,  
       [0051] the first male screw section and the second male screw section are coaxially formed, and  
       [0052] one of the male screw sections is a right-hand screw, and the other male screw section is a left-hand screw.  
       [0053] In the mechanism, a diameter of the second male screw section of the clearance adjusting screw may be shorter than that of the first male screw section,  
       [0054] the second male screw section may be extended from one end of the first male screw section, and  
       [0055] a head section, which contacts the plate, may be provided to the other end of the first male screw section. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0056] Embodiments of the present invention will now be described by way of examples and with reference to the accompanying drawings, in which:  
     [0057]FIG. 1 is a plan view of a chassis of a generic disk player including an optical pick-up, a turn table and three connecting points;  
     [0058]FIG. 2 is a sectional view taken along a line X-X in FIG. 1;  
     [0059]FIG. 3 is a sectional view of a beam angle adjusting mechanism of a first embodiment of the present invention taken along a line Y-Y in FIG. 1;  
     [0060] FIGS.  4 A- 4 C are explanation views of a clearance adjusting screw;  
     [0061]FIGS. 5A and 5B are explanation views of another clearance adjusting screw;  
     [0062] FIGS.  6 A- 6 C are explanation views of examples of standard connecting points;  
     [0063]FIG. 7 is a plan view of the beam angle adjusting mechanism of a second embodiment;  
     [0064]FIG. 8 is a front view of the beam adjusting mechanism seen from a direction of an arrow in FIG. 7; and  
     [0065]FIG. 9 is a sectional view of the conventional beam angle adjusting mechanism taken along the line Y-Y in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
     [0066] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the embodiments, beam angle adjusting mechanisms including clearance adjusting screws will be explained. Note that, the elements described in BACKGROUND OF THE INVENTION are assigned the same symbols and explanation will be omitted.  
     First Embodiment  
     [0067] In the first embodiment, the beam angle adjusting mechanism adjusts inclination of a spindle motor  20 , to which the turn table  18  is attached, with respect to the chassis (a second body)  10 , so that an angle of a laser beam irradiated from the optical pick-up  12 , with respect to the optical disk  14 , can be adjusted.  
     [0068] Firstly, the structure of the beam angle adjusting mechanism will be explained. The basic structure of the beam angle adjusting mechanism  24  of the present embodiment is almost equal to that of the conventional mechanism. Namely, the turn table  18  is fixed to the output shaft of the spindle motor  20 ; the spindle motor  20  is fixed to the motor plate (a first body)  22 ; and the motor plate  22  is connected to the chassis  10  at three connecting points  26 ,  28  and  30 .  
     [0069] As shown in FIG. 1, the connecting points  26 ,  28  and  30  are provided on a circumference, which is coaxial with the output shaft  16 , with angular separation of 90°. The arrangement and number of the connecting points  26 ,  28  and  30  is not limited to the present example. But the connecting points must not be arranged linearly.  
     [0070] In the present embodiment, the connecting point  26  is the standard connecting point; the connecting points  28  and  30  are the adjustable connecting points. By adjusting inclination of the motor plate  22  at the connecting point or points  28  and  30 , the inclination of the turn table  18  with respect to the chassis  10  can be optionally adjusted.  
     [0071]FIG. 3 is the sectional view of the beam angle adjusting mechanism of the present embodiment taken along a line Y-Y in FIG. 1.  
     [0072] As shown in FIG. 3, at the standard connecting point  26 , the stud  32  is provided between the chassis  10  and the motor plate  22 . The stud  32  is fixed by the screw, which is inserted from the motor plate  22  side, so that a clearance between the chassis  10  and the motor plate  22  can be fixed at the standard connecting point  26 .  
     [0073] The stud  32  is formed into a columnar shape. One end face of the stud  32  is fixed to a lower face of the chassis  10 ; a female screw section  36  is formed in the other end face thereof. The screw  34 , which is pierced through a through-hole  38  of the motor plate  22 , is screwed with the female screw section  36 , so that the stud  32  is fixed and the clearance between the chassis  10  and the motor plate  22  can be fixed or maintained at the standard connecting point  26 .  
     [0074] The screw  34  includes a head section  34   a , a large diameter section  34   b  and a small diameter section  34   c . A flat face of the head section  34   a  contacts a lower face of the motor plate  22 , and the large diameter section  34   b  is pierced through the through-hole  38  of the motor plate  22 . A diameter of the small diameter section  34   c  is shorter than that of the large diameter section  34   b . The large diameter section  34   b  and the small diameter section  34   c  are coaxially arranged. A male screw, which can be screwed with the female screw section  36  of the stud  32 , is formed on an outer circumferential face of the small diameter section  34   c.    
     [0075] The ring-shaped elastic member  40 , which is made of an elastic material, e.g., butyl rubber, is provided between the lower face of the stud  32  and an upper face of the motor plate  22  as a shock absorber. Shock and vibration can be absorbed by the elastic member  40 , so that load applied to the standard connecting point  26  can be reduced.  
     [0076] Next, the adjustable connecting points  28  and  30  will be explained. In the present embodiment, clearance adjusting screws  42  are provided to the adjustable connecting points  28  and  30  (see FIG. 3).  
     [0077] The clearance adjusting screw  42  has a head section  44 , a large diameter section  46  and a small diameter section  48 . In the present embodiment, the large diameter section  46  acts as a first male screw section; the small diameter section  48  acts as a second male screw section. The head section  44  is turned, by a tool, e.g., a screw driver. The large diameter section  46  is extended from the head section  44 , and the small diameter section  48  is coaxially extended from the large diameter section  46 . A diameter of the large diameter section  46  is greater than that of the small diameter section  48 . A thread  47  is formed on an outer circumferential face of the large diameter section  46 ; a thread  49  is formed on an outer circumferential face of the small diameter section  48 . In the present embodiment, the thread  47  of the large diameter section  46  is formed as a right-hand screw; the thread  49  of the small diameter section  48  is formed as a left-hand screw.  
     [0078] Note that, in the case that a viewer sees the right-hand screw from one end and a point on the large diameter section  46  is moved along the thread  47  in the clockwise direction, the point is moved away from the viewer; in the case that the viewer sees the left-hand screw from one end and a point on the small diameter section  48  is moved along the thread  49  in the counterclockwise direction, the point is moved away from the viewer.  
     [0079] Function of the clearance adjusting screw  42  at the adjustable connecting point will be explained with reference to FIGS.  4 A- 4 C.  
     [0080] As shown in FIG. 4A, the chassis  10  has a female screw section  50 , which can be screwed with the thread  49  of the small diameter section  48  of the clearance adjusting screw  42 ; the motor plate  22  has a female screw section  52 , which can be screwed with the thread  47  of the large diameter section  46 . Namely, the female screw section  52  acts as a first female screw section; the female screw section  50  acts as a second female screw section.  
     [0081] By inserting the clearance adjusting screw  42  into the female screw section  52  from the lower side of the motor plate  22  with turning the screw  42  in the clockwise direction, the large diameter section  46  of the screw  42  is screwed with the female screw section  52 . The large diameter section  46  is screwed until a flat face of the head section  44  of the screw  42  contacts the lower face of the motor plate  22 . Since the small diameter section  48  of the screw  42  is the left-hand screw, the small diameter section  48  is not screwed with and inserted into the female screw section  50  of the chassis  10 . This state is shown in FIG. 4B.  
     [0082] Then, the clearance adjusting screw  42  is turned in the counterclockwise direction so as to screw the small diameter section  48  with the female screw section  50  of the chassis  10 . By screwing the small diameter section  48  with the female screw section  50 , the chassis  10  is moved toward the large diameter section  46  as shown in FIG. 4C. On the other hand, the motor plate  22  is moved away from the head section  44  toward the small diameter section  48 .  
     [0083] By turning the clearance adjusting screw  42  in the counterclockwise direction, the chassis  10  and the motor plate  22  are gradually moved close to each other. Therefore, the clearance between the chassis  10  and the motor plate  22  can be precisely adjusted. Note that, the standard connecting point  26  acts as a fulcrum point while adjusting the clearance.  
     [0084] The screw  42  can be easily inserted from outside. Since the chassis  10  and the motor plate  22  are screwed with the clearance adjusting screw  42 , they are not influenced by shock and vibration. Thus, the clearance between the chassis  10  and the motor plate  22  can be maintained stably. Unlike the conventional beam angle adjusting mechanism, no coil springs are used in the present embodiment, so the structure can be simplified and number of parts can be reduced.  
     [0085] In the present embodiment, the large diameter section  46  of the adjusting screw  42  is the right-hand screw and the small diameter section  48  is the left-hand screw. The present invention is not limited to the embodiment, so the large diameter section  46  may be the left-hand screw and the small diameter section  48  may be the right-hand screw. Further, the head section  44  is not limited. For example, a head section turned by a wrench may be employed as the head section  44 .  
     [0086] Another clearance adjusting screw is shown in FIGS. 5A and 5B. The clearance adjusting screw  54  has no head section, and diameter of a first male screw section  58 , an intermediate section  60  and a second male screw section  64  are same.  
     [0087] The first male screw section  58  has a thread  57 , which can be screwed with a female screw section (the first female screw section)  56  of the motor plate  22 . The second male screw section  64  has a thread  63 , which can be screwed with a female screw section (the second female screw section)  62  of the chassis  10 . The intermediate section  60  is formed between the first male screw section  58  and the second male screw section  64 . In this example, the thread  57  of the first male screw section  58  is formed as the left-hand screw; the thread  63  of the second male screw section  64  is formed as the right-hand screw.  
     [0088] As shown in FIG. 5A, the clearance adjusting screw  54  is provided between the chassis  10  and the motor plate  22 . By turning the screw  54  in the clockwise direction, the first male screw section  58  and the second male screw section  64  are simultaneously respectively screwed with the female screw sections  56  of the motor plate  22  and the female screw sections  62  of the chassis  10 .  
     [0089] Since the first male screw section  58  is the left-hand screw and the second male screw section  64  is the right-hand screw, the both screw sections  58  and  64  can be simultaneously screwed by turning the screw in the clockwise direction.  
     [0090] With this action, the motor plate  22  is moved toward the chassis  10  as shown in FIG. 5B. Namely, the chassis  10  and the motor plate  22  can be gradually moved close to each other by turning the clearance adjusting screw  54 . Thus, the clearance between the chassis  10  and the motor plate  22  can be precisely adjusted. Since the chassis  10  and the motor plate  22  are screwed with the clearance adjusting screw  54 , the clearance between the chassis  10  and the motor plate  22  can be maintained stably.  
     [0091] Note that, means for turning the screw  54  is not limited. For example, a recess for engaging with a wrench may be formed at a lower end of the first male screw section  58 . In this case, the screw  54  can be easily turned by the wrench.  
     [0092] The intermediate section  60  is formed between the first male screw section  58  and the second male screw section  64 , and has no screw thread. The intermediate section  60  is not an essential element. For example, the second male screw section  64  may be extended from the first male screw section  58  without forming the intermediate section.  
     [0093] In the example shown in FIGS. 5A and 5B, the first male screw section  58  is the left-hand screw; the second male screw section  64  is the right-hand screw. But the present invention is not limited. The first male screw section  58  may be the right-hand screw; the second male screw section  64  may be the left-hand screw.  
     [0094] In the present invention, angle of the threads of the male screw sections are optionally designed. For example, the angle of the first male screw section and the second male screw section may be equal or different.  
     [0095] The structure of the standard connecting point is not limited to the example shown in FIG. 3. Other examples are shown in FIGS.  6 A- 6 C.  
     [0096] In FIG. 6A, a spacer  66  is provided between the chassis  10  and the motor plate  22 . The spacer  66  is fixed on the lower face of the chassis  10 , and a lower curved face of the spacer  66  contacts the upper face of the motor plate  22 . A screw  70  is inserted into a through-hole  68  of the spacer  66  from the motor plate  22  side and screwed with the chassis  10 . With this structure, the spacer  66  is fixed, and the clearance between the chassis  10  and the motor plate  22  can be fixed or maintained.  
     [0097] In FIG. 6B, an elastic member  72 , e.g., a coil spring, is elastically provided between the lower face of the motor plate  22  and a flat face of a head section  70   a  of a screw  70 . The elastic member  72  always biases the motor plate  22  toward the chassis  10  and absorbs shock and vibration.  
     [0098] In FIG. 6C, a projection  74  is projected from the chassis  10  toward the motor plate  22  instead of the spacer  66 . With this structure, the clearance between the chassis  10  and the motor plate  22  can be fixed or maintained.  
     Second Embodiment  
     [0099] In the first embodiment, the motor plate  22  can be inclined with respect to the chassis  10 . By adjusting the inclination angle of the motor plate  22 , the beam angle of the laser beam, which is irradiated from the optical pick-up  12  to the optical disk  14 , can be adjusted.  
     [0100] In the second embodiment, the optical pick-up can be inclined with respect to the chassis, and the beam angle will be adjusted by adjusting an inclination angle of the optical pick-up. The second embodiment will be explained with reference to FIGS.  7  and  8 . Note that, the elements described in the first embodiments are assigned the same symbols and explanation will be omitted.  
     [0101] The optical pick-up  12 , a pair of guide rails  78  for guiding the optical pick-up  12  and a drive unit for moving the optical pick-up along the guide rails  78  are provided to a pick-up plate  76  (the first body).  
     [0102] A rectangular opening section  77  is opened in a center part of the pick-up plate  76 . The guide rails  78  are arranged parallel and fixed along edges of the opening section  77 . The optical pick-up  12  is slidably attached to the guide rails  78 .  
     [0103] The drive unit includes a motor  79 . The motor  79  is fixed to the pick-up plate  76 , a gear  79   b  is attached to an output shaft  79   a . The optical pick-up  12  has a rack  12   a . Reduction gears  80   a ,  80   b  and  80   c  are rotatably provided to the pick-up plate  76 . The gear  79   b  is engaged with the reduction gear  80   a , and the rack  12   a  is engaged with the reduction gear  80   c . With this structure, torque of the motor  79  can be transmitted to the optical pick-up  12 , and the optical pick-up  12  can be linearly moved.  
     [0104] The pick-up plate  76 , which holds the optical pick-up  12 , is connected to the chassis  10  at one standard connecting point  26  and two adjustable connecting points  28  and  30  as well as the first embodiment. With this structure, the pick-up plate  22  can be inclined with respect to the chassis  10 .  
     [0105] The stud  32 , the screw  34  having the large diameter section and the small diameter section, and the elastic member  40  (see FIG. 3) are provided to the standard connecting point  26  so as to fix or maintain a clearance between the chassis  10  and the optical pick-up  76  as well as the first embodiment.  
     [0106] The clearance adjusting screws  42 , each of which has the head section  44 , the large diameter section  46  and the small diameter section  48 , are provided to the adjustable connecting points  28  and  30  as well as the first embodiment. The large diameter sections  46  of the screws  42  are respectively screwed with female screw sections (first female screw sections)  81  of the pick-up plate  76 ; the small diameter sections  48  of the screws  42  are respectively screwed with female screw sections (second female screw sections)  82  of the chassis  10 . With this structure, the clearance between the chassis  10  and the pick-up plate  76  can be adjusted at the adjustable connecting points  28  and  30 . Since the clearance adjusting screws  42  are screwed with the chassis  10  and the pick-up plate  76 , the clearance can be stably maintained. Unlike the conventional beam angle adjusting mechanism, no coil springs are used in the present embodiment, so the structure can be simplified and number of parts can be reduced.  
     [0107] In the present embodiment too, the arrangement and the number of the connecting points is not limited to three. The standard connecting points  26  shown in FIGS.  6 A- 6 C may be employed in the second embodiment. Further, the clearance adjusting screws  54  shown in FIGS. 5A and 5B may be provided to the adjustable connecting points  28  and  30  of the second embodiment.  
     [0108] When the beam angle of the laser beam irradiated from the optical pick-up  12  to the disk  14  is adjusted, the clearance adjusting screws  42  or  54  is turned to vary the clearance between the chassis  10  and the pick-up plate  76  at the points  28  and  30 . With this action, the pick-up plate  76  can be inclined with respect to the chassis  10 . At that time, the standard connecting point  26  acts as a fulcrum point. Therefore, the optical pick-up  12  which is attached to the pick-up plate  76  can be inclined with respect to the chassis  10  and the turn table  18  fixed to the output shaft of the spindle motor  20 , so that the beam angle of the laser beam with respect to the optical disk  14  can be adjusted.  
     [0109] In the above described embodiments, the clearance adjusting screws  42  and  54  are employed in the beam angle adjusting mechanism of the disk player. The clearance adjusting screw of the present invention, of course, may be used for other purposes.  
     [0110] The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by he foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.