JP6381350B2 - Manufacturing method of optical pickup device - Google Patents

Description

  The present invention relates to an optical pickup device having a moving base for moving an objective lens along a recording medium, and more particularly to an optical pickup device having a structure capable of forming a pair of bearing projections provided on the moving base with high accuracy. .

  An optical pickup device for reproducing information from various discs such as a CD and a DVD has a moving base that moves along the recording surface of the disc, and an objective lens facing the recording surface of the disc is supported on the moving base. Has been.

  Patent Document 1 discloses a housing structure corresponding to the moving base. This housing is injection-molded with a resin material, and has a pair of insertion portions that protrude integrally from the side portion of the housing. Each insertion portion is formed in a cylindrical shape, and a pair of insertion portions is inserted through a metal guide shaft, and the housing is guided by the guide shaft and can move along the disk.

  According to the description in paragraph (0022) of Patent Document 1, the insertion portion is formed to be thicker than other portions of the housing in order to firmly support the guide shaft. Moreover, the insertion part is divided into two in the axial direction of the guide shaft, and an open part that opens up and down is provided between the two insertion parts.

JP 2013-186909 A

The shape of the housing described in Patent Document 1 has the following problems.
(1) In order to ensure the strength of the insertion part, the insertion part is formed thicker than the other part of the housing. In injection molding using a resin material, if only a part of the molded product is formed thick, shrinkage occurs when the molten resin filled in the thick part with a mold is cooled. The so-called deformation is likely to occur. As a result, the distortion of the shaft hole formed in each insertion portion, the fall of the center line of the shaft hole, and the like are likely to occur.

(2) In the shape of the housing, it is preferable to form a gate portion for injection molding in one insertion portion that is a thick portion. However, since the insertion part is divided into two with the opening part in between, when molten resin is supplied from the gate part to one insertion part in the injection molding process, the molten resin reaches the other insertion part. The wraparound of resin becomes slow. As a result, the molding accuracy of the insertion portion on the side where the gate portion is not formed tends to be lowered.

SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide a method of manufacturing an optical pickup device having a structure capable of increasing the molding accuracy of a bearing projection formed integrally with a moving base.

The present invention relates to a method of manufacturing an optical pickup device in which a lens holder that holds an objective lens facing a recording medium is mounted on a moving base.
The moving base, by injection molding using a synthetic resin material containing fibers,
It said moving base, and a support body portion that supports the lens holder, and a pair of bearings projections projecting from the side of the supporting body, and a connecting portion connecting between said bearing protrusion protruding from the side the integrally formed, each of the pair of the bearing projections, to form a guide hole coaxially to the connecting portion, the hole portion to extend in parallel to or arranged parallel to the axial center line of the guide hole or a recess,
At this time, the synthetic resin material is advanced from the cavity forming one of the bearing protrusions to the cavity forming the other bearing protrusion through the cavity forming the coupling part. A protrusion and the connecting portion are formed .

  In this case, it is preferable that a gate part for injection molding is provided on one of the bearing protrusions.

  In the present invention, it is preferable that a protruding width dimension W of the coupling portion from the side portion of the support main body portion is coincident with a protruding size of the bearing protrusion portion from the side portion.

  Moreover, it is preferable that the said hole or recessed part is provided over the full length L of the said connection part from the opposing inner surface of one said bearing protrusion to the opposing inner surface of the said other bearing protrusion.

  Furthermore, it is preferable that the said hole or recessed part is arrange | positioned on the centerline which bisects the protrusion width dimension W of the said connection part.

In the manufacturing method of the optical pickup device of the present invention, since the connecting portion that connects between the pair of bearing protrusions integrally protrudes from the side portion of the support main body portion of the moving base, each of the bearing protrusions at this connecting portion. Can be reinforced. Therefore, it is not necessary to excessively increase the thickness of the bearing protrusion, the thickness of each bearing protrusion can be set to an appropriate value, and the molding accuracy of the bearing protrusion can be maintained high.

  In the present invention, since the moving base is formed of a synthetic resin material containing fibers, the strength of the entire moving base is increased. And the hole or recessed part which extends in parallel with the axial centerline of a guide hole, or is arranged in parallel is formed in the connection part which connects a pair of bearing protrusion part. Therefore, in injection molding, the fibers flowing in the mold cavity together with the synthetic resin material are guided by a mold element such as a nest that forms the hole or recess and aligned in a direction parallel to the axial center line. And flow easily. Therefore, the synthetic resin material can easily flow into the two bearing projections, and the molding accuracy of the respective bearing projections is increased. In addition, in the connecting portion, the fibers are easily aligned in parallel with the shaft center line, so that the contraction force or the like that is inclined with respect to the shaft center line is less likely to act on the connecting portion after molding, and is formed in the bearing protrusion. The axis of the guide hole is less likely to fall down.

  In particular, if the injection molded gate portion is formed on one bearing projection, the synthetic resin material injected from the gate portion will be filled into the other bearing projection early through the connecting portion, The molding accuracy of the two bearing projections is improved. Moreover, the fibers injected from the gate portion are easily aligned along the axial center line at the connecting portion.

1 is an exploded perspective view showing an optical pickup device according to an embodiment of the present invention; The fragmentary perspective view which shows the bearing protrusion and connection part of the movement base of the optical pick-up apparatus shown in FIG. The partial cross section perspective view which cuts and shows the movement base shown in FIG. 2 in a connection part, Explanatory drawing explaining the injection molding process of a movement base, In the movement-based injection molding of the embodiment of the present invention, an explanatory diagram simulating the flow of fibers, In the movement-based injection molding of the comparative example, an explanatory diagram that simulates the flow of fibers, A plan view showing a movement base of a modification, A plan view showing a movement base of a modification,

(Overall structure of optical pickup device)
An optical pickup device 1 according to an embodiment of the present invention shown in FIG. 1 is mounted on an optical disk device. The optical disc apparatus has a turntable, and various optical discs (recording media) such as CDs and DVDs are loaded on the turntable and driven to rotate. Then, the information recorded on the recording surface of the optical disc is reproduced or written on the recording surface by the optical pickup device 1.

  The optical pickup device 1 shown in FIG. 1 has a moving base 10. The moving base 10 is formed by an injection molding process using a synthetic resin material containing fibers. The fiber is glass fiber or carbon fiber, and the synthetic resin material containing these fibers is PPS (polyphenylene sulfide). A reference bearing portion 11 and a drive bearing portion 18 are formed on the moving base 10. In the optical disc apparatus, a guide shaft 2 and a drive screw shaft 3 are arranged in parallel to each other. The reference bearing portion 11 is slidably inserted into the guide shaft 2, and an engagement portion 18 a provided on the drive bearing portion 18 is engaged with the screw groove of the drive screw shaft 3. When the drive screw shaft 3 is rotationally driven by a thread motor (not shown), the moving base 10 of the optical pickup device 1 moves in the radial direction (Rad) that is the radial direction of the optical disc D.

  The moving base 10 has a function as an optical base, and various optical components such as a collimating lens 5 and a prism 6 are mounted thereon. Further, a light emitting element and a light receiving element located on the optical axis of the collimating lens 5 are provided.

  A lens driving unit 20 is mounted on the moving base 10. The lens driving unit 20 has a unit chassis 21. The unit chassis 21 is made of sheet metal. The unit chassis 21 has a support reference portion 21a and a pair of adjustment female screw holes 21b and 21c. A fulcrum support 10a is formed on the moving base 10 upward. When the lens driving unit 20 is installed on the moving base 10, the support reference portion 21 a of the unit chassis 21 is installed on the fulcrum support portion 10 a and is supported by the leaf spring 31 fixed to the moving base 10. Is pressed against the fulcrum support 10a.

  An inclination adjusting mechanism 30 is provided between the moving base 10 and the unit chassis 21. In the tilt adjustment mechanism 30, adjustment screws 31 a and 31 b are inserted upward at two locations on the moving base 10. One adjustment screw 31a is screwed into the adjustment female screw hole 21b formed in the unit chassis 21, and the other adjustment screw 31b is screwed into the adjustment female screw hole 21c. Further, a compression coil spring 32a is mounted on the outer periphery of the adjustment screw 31a, and a compression coil spring 32b is mounted on the outer periphery of the adjustment screw 31b, so that the compression coil springs 32a and 32b are interposed between the unit chassis 21 and the moving base 10. Intervene in a compressed state.

  When the tightening amount of the adjusting screw 31a is adjusted after the unit chassis 21 is installed on the moving base 10, the unit chassis 21 is rotated around the Rad axis with the contact portion between the fulcrum support portion 10a and the support reference portion 21a as a fulcrum. Tilted. When the tightening amount of the adjusting screw 31b is adjusted, the unit chassis 21 is tilted about the Tan axis with the contact portion between the fulcrum support portion 10a and the support reference portion 21a as a fulcrum. By this adjustment, the facing angle between the optical axis of the lens driving unit 20 and the optical disk is adjusted.

  As shown in FIG. 1, a support 22 is fixed to the unit chassis 21, and a central portion 23 a of a support substrate 23 is fixed to the back of the support 22. A base portion of the elastic wire 24 is fixed to the support substrate 23. Two elastic wires 24 are fixed to the left and right ends of the support substrate 23, and a total of four elastic wires 24 constitute an elastic support member. The elastic wires 24 pass through the openings 22a formed in the support 22 and extend in parallel to each other in the tangential direction (Tan) which is the tangential direction of the optical disc D.

  The lens driving unit 20 has a lens holder 25. The lens holder 25 is made of synthetic resin or light metal. An objective lens 27 is held by the lens holder 25.

  The lens holder 25 is provided with metal support terminals 26 extending to both sides in the radial direction (Rad). The metal support terminal 26 is embedded and fixed in the lens holder 25. A focus coil Cf is wound around the lens holder 25. Two tracking coils Ct are fixed to each side surface of the lens holder 25 facing the tangential direction (Tan). The terminal portions of the coil winding forming the focus coil Cf are respectively wound around and fixed to two of the four metal support terminals 26. The four tracking coils Ct are connected in series, and the end portions of the coil windings are respectively wound around and fixed to two of the four metal support terminals 26.

  The tip portions of the elastic wires 24 are fixed to the metal support terminals 26 by soldering. The lens holder 25 is supported by four elastic wires 24 so as to be movable in the optical axis direction (F) and the radial direction (Rad). The elastic wire 24 is made of a conductive metal, and the terminal of the coil winding constituting the focus coil Cf is electrically connected to the two elastic wires 24 by the soldering, and the coil winding constituting the tracking coil Ct is connected. The terminal is electrically connected to the other two elastic wires 24. A correction drive current is applied to the focus coil Cf and the tracking coil Ct through the respective elastic wires 24 from a drive circuit (not shown).

  A pair of yoke portions 21e, 21e are bent integrally with the unit chassis 21, and a magnet M is fixed to each of the yoke portions 21e, 21e. Each magnet M faces both the focus coil Cf and the tracking coil Ct mounted on the lens holder 25.

  In the disk device equipped with the optical pickup device 1, when the drive screw shaft 3 rotates, the moving base 10 is moved in the radial direction (Rad). Detection light (laser light) emitted from the light emitting element is reflected by the prism 6 through the collimating lens 5 and applied to the objective lens 27, and the detection light is condensed on the recording surface of the optical disk by the objective lens 27. The return light from the spot of the detection light condensed on the recording surface passes through the objective lens 27, is reflected by the prism 6, and is received by the light receiving element. The information recorded on the recording surface is reproduced by the received light signal.

  Further, a focus error signal and a tracking error signal are detected from the light reception signal. The focus coil Cf and the magnet M constitute a focus correction mechanism, and a correction drive current is applied to the focus coil Cf based on the focus error signal. With this correction drive current and the magnetic field from the magnet M, the lens holder 25 is driven in the optical axis direction (F), and correction is performed so that the detection light continues to be focused on the recording surface of the optical disc.

  The tracking coil Ct and the magnet M constitute a tracking correction mechanism, and a correction drive current is applied to the tracking coil Ct based on the tracking error signal. The lens holder 25 is driven in the radial direction (Rad) by the correction driving current and the magnetic field from the magnet M, and the light spot of the detection light is corrected to follow the recording track on the recording surface.

(Moving base structure and molding method)
In FIG. 2, a part of the movement base 10 is shown in the reverse direction in FIG. 1 in the tangential direction (Tan).

  The moving base 10 has a support main body 19. The lens driving unit 20, the tilt adjusting mechanism 30, and optical components such as the collimating lens 5 and the prism 6 are mounted on the support body 19. The drive bearing portion 18 is also formed in the support main body portion 19. The reference bearing portion 11 extends integrally from a side portion 19a of the support main body portion 19 facing the tangential direction (Tan).

  As shown in FIG. 2, the reference bearing portion 11 has a pair of bearing protrusions 12 and 13. The bearing protrusions 12 and 13 protrude from the side portion 19 a of the support main body portion 19 in the tangential direction (Tan) and are integrally formed with the support main body portion 19. The bearing protrusion 12 and the bearing protrusion 13 are arranged at an interval in the radial direction (Rad), a guide hole 12a is formed in the bearing protrusion 12, and a guide hole 13a is formed in the bearing protrusion 13. Yes. The axial center line O1 of the guide hole 12a and the axial center line O2 of the guide hole 13a are located on the same line in design and extend in the radial direction. The guide hole 13a appears in FIG. 2, and the guide hole 12a appears in FIG.

  In the reference bearing portion 11, a connecting portion 14 is integrally formed between the bearing protrusion 12 and the bearing protrusion 13. As shown in FIG. 2, the bearing protrusions 12, 13 and the connecting portion 14 integrally extend continuously from the side surface 19 a of the support main body 19 in the tangential direction (Tan). In FIG. 2, a radial direction (Rad) interval between the opposed inner surface 12 b of the bearing projection 12 and the opposed inner surface 13 b of the bearing projection 13 is indicated by a dimension L. The connecting portion 14 means a portion of the reference bearing portion 11 located between the opposed inner surface 12b and the opposed inner surface 13b. Therefore, the radial dimension of the connecting portion 14 is L.

  In FIG. 2, the protrusion width dimension in the tangential direction (Tan) of the connecting portion 14 from the side portion 19a of the support main body portion 19 is indicated by W. The protrusion width dimension W coincides with the protrusion width dimension in the tangential direction from the side portion 19 a of the bearing protrusions 12 and 13.

  As shown in FIG. 3, the shape of the inner surface 14 a facing the guide shaft 2 of the connecting portion 14 is substantially a part of a cylindrical surface. In the plan view of the reference bearing portion 11 as viewed from above, the connecting portion 14 has the width dimension W determined so that the guide shaft 2 can be completely covered.

  The connecting portion 14 is formed with a hole portion 15 penetrating vertically. The hole 15 is a long hole and extends parallel to the axial center lines O1 and O2. The hole 15 is continuously formed without interruption in the range of the distance L from the opposed inner surface 12b to the opposed inner surface 13b. The opening width dimension B in the tangential direction of the hole 15 is smaller than the inner diameter of the guide holes 12a and 13a, that is, the diameter of the guide shaft 2. Preferably, the opening width dimension B is not more than 1/2 of the inner diameter or the diameter. . The center line that bisects the width dimension B of the hole 15 preferably matches the center line that bisects the width dimension W of the connecting portion 14.

  As shown in FIGS. 2 and 3, in the moving base 10, the gate portion 16 in the injection molding process is formed on the side surface of one bearing protrusion 12. This moving base 10 is provided with only one gate portion 16.

  FIG. 4 is an explanatory view showing a process of injection molding the moving base. A cavity in the mold for molding the moving base 10 is indicated by reference numeral 10A.

  Molten resin containing fibers such as glass fibers is injected from the gate G into the cavity 10A. In the cavity 10 </ b> A, the molten resin proceeds with a spread as indicated by S <b> 1 → S <b> 2 → S <b> 3 →. When the molten resin is injected from the gate G into the cavity 12A that forms the bearing projection 12, the molten resin travels through the cavity 14A that forms the connecting portion 14, and the cavity 13A that forms the bearing projection 13 Migrate in.

  When the gate portion 16 is formed on the bearing protrusion 12 and the connecting portion 14 for connecting the bearing portions 12 and 13 is provided, the cavities 12A and 13A for forming the bearing protrusions 12 and 13 are formed at an early stage. The molten resin comes to wrap around, and the molten resin reaches the cavities 12A and 13A sufficiently, so that the molding accuracy of the bearing projections 12 and 13 and the guide holes 12a and 13a can be increased.

  As shown in FIG. 4, a mold element 15 </ b> A such as a nest for forming the hole 15 exists in the cavity 14 </ b> A that forms the connecting portion 14. The mold element 15A is disposed so as to vertically penetrate the cavity 14A. Therefore, when the molten resin supplied to the cavity 12A passes through the cavity 14A and reaches the cavity 13A, the flow of the molten resin is aligned in the direction Sa parallel to the axial centerlines O1 and O2 by the mold element 15A. . As a result, in the connecting portion 14 after molding, the extending direction of the fibers in the synthetic resin material is easily aligned in a direction parallel to the axial center lines O1 and O2.

  FIG. 5 is a simulation result showing the flow of fibers in the molten resin when the cavity shown in FIG. 4 is used. FIG. 6 shows a mold having the same cavity as that shown in FIG. It is a simulation result which shows the flow of the fiber in the state which does not provide the element 15A.

  As shown in FIG. 5, in the embodiment of the present invention, the fibers are aligned so as to be parallel to the axial center lines O1 and O2 in the cavity 14A for molding the connecting portion 14, whereas FIG. In the comparative example, it is understood that the fibers are not aligned in the cavity 14A and the directions are disordered.

  A molded article using a synthetic resin material containing fibers has higher mechanical strength than a molded article formed of a synthetic resin material not containing fibers. However, in injection molding with synthetic resin material containing fibers, the shrinkage direction when the molten resin cools is not isotropic, and in a direction orthogonal to the fiber arrangement direction rather than the shrinkage rate in the fiber arrangement direction. The seed reduction rate is higher.

  Therefore, as in the comparative example of FIG. 6, when the fiber orientation is not uniform in the cavity 14A and the fiber orientation is oblique with respect to the axial center lines O1 and O2, the shrinkage force during resin cooling is It will be inclined obliquely with respect to the axial center line O1 or O2, and stress that is inclined obliquely with respect to the axial center line O1 or O2 tends to remain in the connecting portion 14 after molding. When this phenomenon becomes remarkable, the parallelism between the opposed inner surfaces 12b and 13b of the one bearing projection 12 and the other bearing projection 13 cannot be maintained, and the axial centerlines O1 and O2 are in the design radial direction (Rad). ). Further, since the dimensions of the respective parts of the moving base 10 are all determined based on the axial center lines O1 and O2 of the guide holes 12a and 13a, if an error occurs in the direction of the axial center lines O1 and O2, the radial direction The position error of each part on the moving base 10 to be used as a reference for the above becomes cumulatively large.

  Further, if the axial center line O1 of the guide hole 12a and the axial center line O2 of the guide hole 13a cannot be positioned on the same line, the sliding load when the guide holes 12a and 13a slide on the guide shaft 2 is also large. turn into.

  On the other hand, in the embodiment of the present invention shown in FIG. 5, the fibers of the molten resin are easily aligned in the direction Sa parallel to the axial centerlines O1 and O2 in the cavity 14A forming the connecting portion 14. As a result, the shrinkage direction when the resin is cooled does not vary, and the resin can be uniformly directed in the tangential direction (Tan), and the axial center lines O1 and O2 are inclined from the designed radial direction (Rad). The phenomenon is less likely to occur. Furthermore, since there is a die element 15A extending in the radial direction in the cavity 14A and the cavity 14A is divided into two, even if a shrinkage force in the tangential direction acts during cooling of the resin, the influence of this shrinkage force is reduced. Can be reduced.

  In particular, as shown in FIG. 2, the center line that bisects the hole 15 into the width dimension B (center line extending in the radial direction) is the center line that bisects the connecting part 14 into the width dimension W (center line extending in the radial direction). ) And the hole 15 is formed over the entire length of the length L of the connecting portion 14, the connecting portion 14 can be divided into two in the width direction over the entire length of the length L. It becomes possible to reduce the influence of the shrinkage force due to the cooling of the resin containing.

  As described above, in the embodiment of the present invention, the accuracy of the relative position between the bearing projection 12 and the bearing projection 13 can be improved after molding, and the shaft center axis O1 of the guide hole 12a and the axis of the guide hole 13a The center line O2 can be set parallel to the designed radial direction. Therefore, in each part of the movement base 10, the precision of the molding position of each part can be set high on the basis of the axial centerlines O1 and O2.

Next, FIGS. 7 and 8 show a modification of the embodiment of the present invention.
In the modification shown in FIG. 7, the holes 15a and 15b are divided in the radial direction. The hole portion can be further divided into three or more. If the divided holes are linearly arranged in the radial direction, the flow direction of the fibers in the cavity 14A can be easily aligned in the radial direction as shown in FIG.

  In the modification shown in FIG. 8, two (a plurality) holes 15c and 15d are formed in parallel with each other. The holes 15c and 15d are elongated holes that are continuous in the radial direction, and the two holes 15c and 15d have a uniform distance in the tangential direction around the axis center lines O1 and O2 when viewed in plan view. Is formed. Also in this embodiment, as shown in FIG. 5, the flow direction of the fibers in the cavity 14A can be easily aligned in the radial direction.

  Further, in order to align the flow of fibers, a groove extending in the radial direction may be used instead of the hole 15. In this case, the groove portion needs to be deep enough to make the flow of the molten resin uniform, and the depth of the groove portion needs to be 2/3 or more of the thickness of the connecting portion 14. More preferably, the depth of the groove is 3/4 or more of the wall thickness. In the embodiment shown in FIG. 2, grooves 16 a and 16 b extending in the radial direction are formed in the connecting portion 14, but these grooves are for adjusting the thickness of the connecting portion 14. It is not included in the intended groove.

DESCRIPTION OF SYMBOLS 1 Optical pick-up apparatus 10 Moving base 11 Reference | standard bearing part 12, 13 Bearing protrusion part 12a, 13a Guide hole 12b, 13b Opposite inner surface 14 Connection part 15, 15a, 15b, 15c, 15d Hole part 20 Lens drive unit 21 Unit chassis 22 Support Body 24 Elastic wire (elastic support member)
25 Lens holder 27 Objective lens 30 Tilt adjustment mechanism Cf Focusing coil Ct Tracking coil O1, O2 Axis center line M Magnet F Optical axis direction W Linking portion protruding width L Linking portion length Rad Radial direction Tan Tangental direction

Claims (5)

In the manufacturing method of the optical pickup device in which the lens holder that holds the objective lens facing the recording medium is mounted on the moving base,
The moving base, by injection molding using a synthetic resin material containing fibers,
It said moving base, and a support body portion that supports the lens holder, and a pair of bearings projections projecting from the side of the supporting body, and a connecting portion connecting between said bearing protrusion protruding from the side the integrally formed, each of the pair of the bearing projections, to form a guide hole coaxially to the connecting portion, the hole portion to extend in parallel to or arranged parallel to the axial center line of the guide hole or a recess,
At this time, the synthetic resin material is advanced from the cavity forming one of the bearing protrusions to the cavity forming the other bearing protrusion through the cavity forming the coupling part. A method of manufacturing an optical pickup device , wherein a protrusion and the connecting portion are formed . The gate portion of the injection molding method of one of the optical pickup device provided Ru claim 1, wherein the bearing projection. 3. The method of manufacturing an optical pickup device according to claim 1, wherein a protruding width dimension W of the coupling portion from the side portion of the support main body portion is the same as a protruding size of the bearing protrusion portion from the side portion. . The hole or recess from opposite inner surface of one of the bearing protrusion to the opposite inner surface of the other of the bearing projection, on one of 3 claims 1 provided over the entire length L of the connecting portion The manufacturing method of the optical pick-up apparatus of description. The hole or recess is a method of manufacturing an optical pickup device according to any one of claims 1 to 4 is arranged on a center line bisecting the projected width W of the connecting portion.

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