Abstract:
There is provided an optical head having a simple structure not to require a lot of time and effort in production and assembling as well as capable of applying a laser beam stably to the recording layer of an optical disk. A laser light source  11 , a rectangular parallelepiped laser holder  12  for press-fitting the laser light source  11  therein, an elastic holder supporting member  13  for elastically supporting the laser holder  12 , and clip portions  14  for fixing a base Bs and the elastic holder supporting member  13  stably and elastically are mounted on the base Bs, and notch portions  135  are formed in the elastic holder supporting member  13.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an optical head for recording and (or) reading data by applying light to an optical disk.  
         [0003]     2. Description of the Prior Art  
         [0004]     Recently, there are widely used apparatuses that utilize an optical disk, onto/from which videos, audios, and/or information can be recorded and (or) read by applying light, as a recording medium. CDs (Compact Disks), DVDs (Digital Versatile Disks), and the like are widely used as such an optical disk. Optical disk apparatuses that utilize such an optical disk as a recording medium to record and (or) read data onto/from the optical disk include an optical head for applying a laser beam to the recording surface of the optical disk and for detecting reflected light.  
         [0005]      FIG. 1  is a view showing an arrangement in an optical head. As shown in  FIG. 1 , there are provided a laser light source  11 , a mirror Mr, a collimator lens  3 , an objective lens  4 , a beam splitter Sp, and a light receiving element Pd. A laser beam emitted from the laser light source  11  is reflected at the mirror Mr to enter the collimator lens  3 . The laser beam incident to the collimator lens  3  is output as parallel light to enter the objective lens  4 . The laser beam incident to the objective lens  4  is applied to the recording surface of a Optical disk Ds.  
         [0006]     In the case above, the laser beam is applied focusing on the recording layer of the Optical disk Ds with the optical axis thereof being perpendicular to the recording layer of the Optical disk Ds. The beam splitter Sp is a prism for transmitting a half of the incident laser beam and for reflecting the other half, adapted to guide the light reflected at the Optical disk Ds toward the light receiving element Pd. The light receiving element Pd is adapted to convert light into current and to read data based on the intensity of the light.  
         [0007]      FIG. 6  is a perspective view of a conventional laser optical system. The laser optical system  91  is mounted on a base Bs, including a laser light source  92 , a laser holder  93  in which the laser light source  92  is press-fitted, and an elastic holder supporting member  94  for supporting the laser holder  93 .  
         [0008]     The laser holder  93  here has a rectangular parallelepiped shape, though not restricted thereto, in the central part thereof being fitted the laser light source  92  detachably. The elastic holder supporting member  94  has: a rectangular bottom portion  940  to be in contact with the base Bs; a first supporting portion  941  connected perpendicularly to the bottom portion  940  and covering almost all of a side surface of the laser holder  93 ; a second supporting portion  942  connected perpendicularly to the bottom portion  940  and facing the first supporting portion  941  to support a part of another side surface of the laser holder  93 ; and clip portions  943  fitted to a side portion of the bottom portion  940  to clip the base Bs.  
         [0009]     As shown in  FIG. 6 , the laser light source  92  includes power supply terminals  921  for supplying power. Supplying power through the power supply terminals  921  causes the laser light source  92  to emit a laser beam. Also, in the base Bs and elastic holder supporting member  94 , there are formed through holes for passage of laser beams, though not shown in the figure.  
         [0010]      FIG. 7  is a side view of the conventional laser optical system shown in  FIG. 6 . As shown in  FIG. 7 , the clip portions  943  of the laser optical system  91  clip and hold the base Bs. The laser holder  93  is supported by the first and second supporting portions  941  and  942  of the elastic supporting member  94  so that the bottom portion of the laser holder  93  is not brought into contact with the bottom portion of the elastic supporting member  94 .  
         [0011]     In the state above, the angle of the laser holder  93  (laser light source  92 ) is adjusted so that laser beams emitted from the laser light source  92  travel on a predetermined optical path. Then, adhesion is provided at contact areas between the bottom portion  940  of the elastic supporting member  94  and the base Bs, contact areas between the first supporting portion  941  and the base Bs, and contact areas between the first supporting portion  941  and the laser holder  93  using adhesive  95  so that the laser optical system  91  is fixed to the base Bs (refer to Japanese Patent Laid-Open Publication No. 2004-178626 for example).  
         [0012]     In the case of mounting the laser light source  92  on the base Bs, it is often the case that thermosetting adhesive, which is hardened by heating, is generally used as the adhesive  95 . Thermosetting adhesive can be applied and hardened easily owing to its characteristics. However, in the case of mounting the laser holder  93  using the conventional elastic supporting member  94 , it is necessary to provide adhesion between the base Bs and the elastic supporting member  94  as well as between the elastic supporting member  94  and the laser holder  93 , resulting in taking a lot of time and effort in assembling even if easy-to-use thermosetting adhesive may be used.  
         [0013]     If the base Bs, laser holder  93 , and elastic supporting member  94  could be joined with adhesive at one time, it would be possible to save time and effort for assembling, but the adhesion may be made unstable, resulting in a possibility of misalignment of the optical axis of laser beams.  
         [0014]     When the optical axis of laser beams is misaligned, it is difficult to apply a laser spot obtained by converging the laser beams to an appropriate position in the data layer of the optical disk. The displacement of the laser spot may result in that data recorded on the optical disk cannot be read properly. If data recorded on the optical disk cannot be read properly, videos and/or audios may be interrupted and the worst thing that can happen is the impossibility of reproduction in, for example, a DVD player. Also, in the case of a recordable optical head, since the laser spot cannot be applied to a predetermined position, it may be difficult to record appropriate data on the optical disk and/or it may take quite a lot of time to record the data.  
       SUMMARY OF THE INVENTION  
       [0015]     Hence, it is an object of the present invention to provide an optical head having a simple structure not to require a lot of time and effort in production and assembling as well as capable of preventing the optical axis of a laser beam emitted from a laser optical system from being misaligned and therefore of reading and (or) recording data from/onto an optical disk stably.  
         [0016]     It is another object of the present invention to provide an optical head capable of fixing a laser holder, an elastic supporting member, and a base stably with a small amount of adhesive by ensuring a large effective adhesion area with a simple structure and therefore of reducing cost in production and assembling.  
         [0017]     In order to achieve the foregoing objects, the present invention is directed to an optical head including: a laser optical system for emitting a laser beam; a mirror for reflecting the laser beam; a collimator lens for converting the laser beam into parallel light; an objective lens for applying the laser beam to an optical disk; a beam splitter for splitting light reflected at the optical disk; and a light receiving element for receiving light, the laser optical system being mounted on a base and having a laser light source, a laser holder in which the laser light source is press-fitted, and an elastic holder supporting member for supporting the laser holder, wherein the elastic holder supporting member includes: a rectangular bottom portion to be in contact with the base; a first supporting portion connected perpendicularly to the bottom portion and covering almost all of a side surface of the laser holder; a second supporting portion connected perpendicularly to the bottom portion and facing the first supporting portion to support a part of another side surface of the laser holder; and a clip member for clipping and fixing the base, engageable convex portions adapted to be engaged with engageable recessed portions formed in each contact surface of the laser holder being formed on the first and second supporting portions, and wherein rectangular notch portions are formed on either end of a section in the first supporting portion that is connected to the bottom portion, and the length of a straight line lying between the deepest portions of the notch portions is smaller than the longitudinal length of the side surface of the laser holder that is in contact with the first supporting portion.  
         [0018]     In order to achieve the foregoing objects, the present invention is also directed to an optical head including: a laser optical system having a laser light source, a laser holder in which the laser light source is press-fitted, and an elastic holder supporting member for supporting the laser holder; and a base for arranging the laser optical system thereon, wherein the elastic holder supporting member includes: a rectangular bottom portion to be in contact with the base; a first supporting portion connected perpendicularly to the bottom portion and covering almost all of a side surface of the laser holder; and a second supporting portion connected perpendicularly to the bottom portion and facing the first supporting portion to support a part of another side surface of the laser holder, and wherein notch portions are formed on either end of a connecting portion between the first supporting portion and the bottom portion.  
         [0019]     In the arrangement above, the notch portions may be formed in the first supporting portion or in the bottom portion. The notch portions each may have a rectangular shape. In addition, the length of a straight line lying between the deepest portions of the notch portions may be smaller than the longitudinal length of the side surface of the laser holder that is in contact with the first supporting portion.  
         [0020]     In accordance with the present invention, the optical head has a simple structure not to require a lot of time and effort in production and assembling, and it is possible to prevent the optical axis of a laser beam emitted from the laser optical system from being misaligned and therefore to read and (or) record data from/onto an optical disk stably.  
         [0021]     Also, in accordance with the present invention, it is possible to fix the laser holder, elastic supporting member, and base stably with a small amount of adhesive by ensuring a large effective adhesion area with a simple structure and therefore to reduce cost in production and assembling. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  is a view showing an arrangement in an optical head;  
         [0023]      FIG. 2  is a perspective view of a laser optical system to be used in an optical head according to the present invention;  
         [0024]      FIG. 3  is a side view of the laser optical system shown in  FIG. 2 ;  
         [0025]      FIG. 4 (A) is a perspective view of an elastic holder supporting member to be used in the optical head according to the present invention and  FIG. 4 (B) is a front view of the elastic holder supporting member shown in  FIG. 4 (A);  
         [0026]      FIG. 5  is a perspective view of an elastic holder supporting member to be used in the optical head according to the present invention;  
         [0027]      FIG. 6  is a perspective view of a conventional laser optical system; and  
         [0028]      FIG. 7  is a side view of the conventional laser optical system shown in  FIG. 6 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]     Embodiments of the present invention will hereinafter be described with reference to the accompanying drawings.  FIG. 1  is a view showing an arrangement in an optical head. The optical head shown in  FIG. 1  has substantially the same structure as in the conventional art. That is, there are provided a laser light source  11 , a mirror Mr, a collimator lens  3 , an objective lens  4 , a beam splitter Sp, and a light receiving element Pd. A laser beam emitted from the laser light source  11  is reflected at the mirror Mr to enter the collimator lens  3 , and then is converted into parallel light to be output from the collimator lens  3 . The laser beam output from the collimator lens  3  enters the objective lens  4  to be applied to a Optical disk Ds by the objective lens  4 .  
         [0030]     In the case above, the laser beam is applied focusing on the recording layer of the Optical disk Ds with the optical axis thereof being perpendicular to the recording layer of the Optical disk Ds. The beam splitter Sp is a prism for transmitting a half of the incident laser beam and for reflecting the other half, adapted to guide the light reflected at the Optical disk Ds toward the light receiving element Pd. The light receiving element Pd is adapted to convert light into current and to read data based on the intensity of the light.  
         [0031]     The order of applying a laser beam to the above-described optical members is not restricted thereto, but may be permuted to the extent possible. Unnecessary ones among the above-described optical components, if any, may also be removed, while necessary ones, if any, may be added.  
         [0032]      FIG. 2  is a perspective view of a laser optical system to be used in an optical head according to the present invention and  FIG. 3  is a side view of the laser optical system shown in  FIG. 2 . The laser optical system  1  shown in  FIGS. 2 and 3  is mounted on a base Bs of the optical head and has a laser light source  11 , a rectangular parallelepiped laser holder  12  in which the laser light source  11  is press-fitted, an elastic holder supporting member  13  for elastically supporting the laser holder  12 , and clip portions  14  for fixing the base Bs and the elastic holder supporting member  13  stably and elastically. In the base Bs, there is formed a through hole Bsh for passage of laser beams.  
         [0033]     The laser holder  12  has a press-fit hole  120  for press-fitting the laser light source  11  therein. The press-fit hole  120  is a through hole, and laser beams are to be emitted from the side opposite to that through which the laser light source  11  is press-fitted. The laser light source  11  has power supply terminals  111 , and supplying power to the terminals  111  causes a laser beam to be emitted. First engageable recessed portions  121  adapted to be engaged with first engageable convex portions  133  to be described hereinafter are formed at portions in the laser holder  12  where to be in contact with a first supporting portion  131  to be described hereinafter. Also, second engageable recessed portions  122  adapted to be engaged with second engageable convex portions  134  to be described hereinafter are formed at portions where to be in contact with a second supporting portion  132  to be described hereinafter (refer to  FIG. 3 ).  
         [0034]      FIG. 4 (A) is a perspective view of an elastic holder supporting member to be used in the laser optical system in the optical head according to the present invention and  FIG. 4 (B) is a front view of the elastic holder supporting member shown in  FIG. 4 (A). As shown in  FIG. 4 , the elastic holder supporting member  13  includes: a rectangular bottom portion  130 ; a first supporting portion  131  connected perpendicularly to the bottom portion  130  and covering almost all of a side surface of the laser holder  12 ; and a second supporting portion  132  connected perpendicularly to the bottom portion  130  and facing the first supporting portion  131  to support a part of another side surface of the laser holder  12 . In the bottom portion  130 , there is formed a through hole  13   h  for passage of laser beams.  
         [0035]     The first and second supporting portions  131  and  132  can be deformed elastically and therefore can press the laser holder  12  elastically. The first engageable convex portions  133  adapted to be engaged with the first engageable recessed portions  121  are formed on the inside surface of the first supporting portion  131 , while the second engageable convex portions  134  adapted to be engaged with the second engageable recessed portions  122  are formed on the inside surface of the second supporting portion  132 .  
         [0036]     As shown in FIGS.  4 (A) and  4 (B), rectangular notch portions  135  are provided on either end of a section in the first supporting portion  131  that is connected to the bottom portion  130 . The distance L 1  between the notch portions  135  on either end is made smaller than the length L 2  of the laser holder  12 .  
         [0037]     The clip portions  14  are formed integrally with the bottom portion  130  of the elastic holder supporting member  13  and are arranged on either side of the second supporting portion  132 , though not restricted thereto. The clip portions  14  each have a first latch portion  141  and a connecting portion  142  for connecting the first latch portion  141  and the bottom portion  130 . The first latch portion  141  is adapted to extend around to the side opposite to that on which the base Bs is in contact with the bottom portion  130  and to press the base Bs elastically to prevent the laser optical system  1  from being separated from the base Bs. The first latch portion  141  and connecting portion  142  can be deformed elastically and therefore can support the base Bs elastically, even if the thickness of the base Bs may be changed, as long as the change is within a predetermined range.  
         [0038]     When the laser holder  12  is arranged between the first and second supporting portions  131  and  132  of the elastic holder supporting member  13  and the first and second engageable recessed portions  121  and  122  are engaged, respectively, with the first and second engageable convex portions  133  and  134 , the elastic holder supporting member  13  supports the laser holder  12 . In this case, the bottom surface of the laser holder  12  and the bottom portion  130  of the elastic holder supporting member  13  are not in contact with each other.  
         [0039]     The laser holder  12  is mounted in such a manner that laser beams emitted from the laser light source  11  pass through the through hole  13   h  in the elastic holder supporting member  13 . Also, the elastic holder supporting member  13  is arranged in such a manner that the through hole  13   h  is overlapped with the center axis of the through hole Bsh in the base Bs. Laser beams are to be emitted through the through hole  13   h  in the elastic holder supporting member  13  and the through hole Bsh in the base Bs.  
         [0040]     As shown in  FIGS. 2 and 3 , the elastic holder supporting member  13  is fixed to the base Bs using adhesive  2 . The adhesive  2  is put into the notch portions  135  formed in a section in the first supporting portion  131  of the elastic holder supporting member  13  that is connected to the bottom portion  130 . As shown in  FIG. 3 , the adhesive  2  is put into the notch portions  135  to be applied to the base Bs, laser holder  12 , bottom portion  130 , and first supporting portion  131 , so that these components can be fixed to each other.  
         [0041]     Although the end portions of the first supporting portion  131  may be entirely the notch portions  135 , it is preferable that the notch portions  135  be formed in the vicinity of sections (lower parts) in the end portions of the first supporting portion  131  that are connected to the bottom portion  130  as shown in  FIG. 4 , because adhesive can be applied to the rest areas in the end portions of the first supporting portion  131 , in which the notch portions  135  are not formed, to achieve an increased effective adhesion area. Although the notch portions  135  each have, for example, a rectangular shape in the description of the present embodiment, the shape is not restricted thereto, and it is possible to widely employ shapes with which the length between the deepest portions of the notch portions  135  is made smaller than the length of the laser holder  12  and whereby the base Bs, laser holder  12 , bottom portion  130 , and first supporting portion  131  can be fixed to each other at one injection of adhesive.  
         [0042]      FIG. 5  is a perspective view of another elastic holder supporting member to be used in the laser optical system in the optical head according to the present invention. In the elastic holder supporting member  13   b  shown in  FIG. 5 , notch portions  135   b  are provided in the bottom portion  130   b . Also, since the rest has substantially the same arrangement as the elastic supporting member  13 , substantially identical members are designated by the same reference numerals.  
         [0043]     Forming the notch portions  135   b  in the bottom portion  130   b  allows the amount of inflow adhesive  2  to be applied to the first supporting portion  131   b  to be reduced. Further, although the effective adhesion area is reduced because the adhesive  2  is not applied to the side of the first supporting portion  131   b  opposite to the laser holder  12 , it is possible to prevent the adhesive  2  from being applied to the side of the first supporting portion  131   b  opposite to the laser holder  12 .  
         [0044]     Although the notch portions  135  and  135   b  each have, for example, a rectangular shape in the descriptions of the above-described embodiments, the shape is not restricted thereto, and it is possible to widely employ shapes with which the length between the deepest portions of the notch portions  135  and  135   b  is made smaller than the length of the laser holder  12  and whereby the base Bs, laser holder  12 , bottom portion  130 , and first supporting portion  131  can be fixed to each other at one injection of adhesive.  
         [0045]     The adhesive  2  used in the above-described embodiments is thermosetting adhesive, which may come away by heat and/or moisture, etc. even after adhesion. Even when the adhesive may come away or may be loosened, the laser optical system  1  cannot be separated from the base Bs because the clip portions  14  are installed and it is therefore possible to prevent misalignment of the optical axis, whereby laser beams can be emitted stably and thereby the optical head can be operated stably. Although the adhesive is, for example, thermosetting one in the descriptions here, even another type of adhesive may be used in the same way.  
         [0046]     The optical head according to the present invention is applicable to optical disk apparatuses for reading information by applying a laser beam to an optical disk such as DVD, CD, or LD and/or for recording information onto a writable optical disk.