JP5436379B2 - Optical pickup objective lens drive device - Google Patents

Description

  The present invention relates to an optical pickup for recording / reproducing information on / from a disc-shaped recording medium such as a DVD or CD, and in particular, a lens holder for holding an objective lens is elastically supported by a plurality of wires. The present invention relates to an objective lens driving device for an optical pickup.

  Generally, in this type of optical pickup objective lens driving device, both sides of a lens holder that holds the objective lens are elastically supported by a total of four (or six) conductive wires. That is, the free end side of each wire supports the lens holder, and the fixed end side of each wire is fixed to the support member and the back substrate. The back substrate is fixed to the back side of the support member, and this support member is fixed to a base member provided with a magnetic circuit (magnet or yoke) for generating magnetic flux. The objective lens is disposed at a position facing the recording surface of a disk-shaped recording medium (hereinafter abbreviated as “disk”), and the light beam emitted from the light source (semiconductor laser) of the optical pickup is converged by the objective lens to perform the recording. Information is recorded / reproduced by irradiating the surface. At this time, focus servo and tracking servo for controlling the spot diameter of the light beam with respect to the recording surface of the disk are applied. In the case of a moving coil system in which a focus coil and a tracking coil that cross the magnetic flux are attached to a lens holder, one end of each wire is connected to the focus coil and tracking coil on the lens holder side, and the other end of each wire is the back surface. Connected to the board. Since this back substrate is connected to the external drive circuit via the flexible wiring substrate, by energizing the focus coil via a predetermined wire, an electromagnetic force is generated in the direction along the optical axis of the objective lens. The lens holder can be driven in the direction, which enables focus correction of the objective lens. Similarly, by energizing the tracking coil via another wire, an electromagnetic force can be generated in a direction orthogonal to the optical axis of the objective lens, and the lens holder can be driven in that direction. Tracking correction is possible.

  When attaching a wire in the assembling process of such an objective lens driving device, a wire cut in advance to a predetermined length is inserted into a guide hole on the fixed part side (supporting member side), and further, the tip part of the wire Is inserted into the guide hole on the movable part side (lens holder side), and then the adhesive is filled in the guide hole on the fixed part side to fix the wire. Further, since the positional deviation of the wire is a major factor that impairs the operation characteristics of focus correction and tracking correction, the attachment position must be accurately defined by inserting the wire into the guide hole. Therefore, normally, when a wire is inserted into a tapered guide hole formed in a tapered shape, the wire is positioned by the tip of the guide hole.

  FIG. 7 is an explanatory view showing a wire attachment structure in a conventional objective lens driving device (see, for example, Patent Document 1). As shown in FIG. 7, the wire 20 passes through the loose insertion hole 21 a of the back substrate 21 and the guide hole 22 a of the support member 22 and is inserted into the guide hole 23 a of the lens holder 23. The wire 20 is soldered to a land portion (not shown) formed around the loose insertion hole 21a on the back surface of the back substrate 21, and the focus coil or tracking is passed through the guide hole 23a of the lens holder 23. Soldered to the coil lead-out part. The loose insertion hole 21a of the rear substrate 21 is formed in a cylindrical shape having a large diameter so that the wire 20 can be easily inserted. Each of the support member 22 and the lens holder 23 is a molded product of a synthetic resin. The guide hole 22a of the support member 22 has a substantially conical shape, and only the tip portion is formed in a cylindrical shape slightly larger in diameter than the wire 20. Yes. The guide hole 23 a of the lens holder 23 is also substantially conical, and only the tip is formed in a cylindrical shape having a slightly larger diameter than the wire 20. Since the position of the guide hole 23a is uniquely defined from the center of gravity of the lens holder 23 and the like, in order to secure a required length L in a portion where the wire 20 is easily elastically deformed (effective portion), The guide hole 22a is set to a relatively short depth (for example, about 0.6 mm). And when attaching the wire 20, after inserting the wire 20 through the loose insertion hole 21a of the back substrate 21, it is inserted into the guide hole 22a by being guided by the conical surface of the guide hole 22a of the support member 22, Then, the guide hole 23a is inserted through the conical surface of the guide hole 23a of the lens holder 23. After the wire 20 is inserted and positioned in the guide holes 22a and 23a in this way, the wire 20 is fixed in a positioned state by applying an adhesive (not shown) in the guide hole 22a, and both ends of the wire 20 are coiled. The lead-out portion and the land portion of the rear substrate 21 are soldered.

Japanese Patent Laid-Open No. 10-289455

  As described above, since the wires inserted into the tapered guide holes of the lens holder and the support member are positioned by the tip portions of these guide holes, the tip portion of the guide hole is used to increase the positioning accuracy of the wire. The inner diameter of the wire may be set substantially equal to the outer diameter of the wire. For example, in the case of the conventional example shown in FIG. 7, if the guide hole 22a and the tip end of the guide hole 23a, which are formed in a substantially conical shape, are formed in a cylindrical shape to which the wire 20 can be inserted with almost no gap, This wire 20 can be attached with high positional accuracy. However, since a molding burr is generated in the support member 22 and the lens holder 23 which are resin molded products, when the guide hole 22a and the tip end portion of the guide hole 23a are made as thin as possible, the wire 20 is caused by a slight molding burr generated there. There is a risk of being unable to insert. For this reason, conventionally, the inner diameter of the tip of the guide hole 22a or the guide hole 23a is often set to about twice the outer diameter of the wire 20, and the positioning effect on the wire 20 is insufficient. It was.

  Therefore, the present inventors examined a case where the guide hole 22a of the support member 22 is formed in a quadrangular pyramid shape and the tip portion 22b of the guide hole 22a is square as shown in FIG. In the case of such a quadrangular pyramid, although a minute molding burr is generated at the tip 22b of the guide hole 22a similarly to the cone, this molding burr occurs mainly at the corners of the four corners of the square, so the tip 22b. Even if the cross-sectional shape is a square that is small enough to circumscribe the wire, it is presumed that the molding burr is less likely to hinder the insertion of the wire. However, as shown in the sectional view of FIG. 9, when the guide hole 22a of the support member 22 having a short depth is formed in a quadrangular pyramid shape, the inclination of the ridge line portion 22c of the guide hole 22a becomes excessively gentle. In addition, since the wire 20 is easily fitted in the V-shaped groove defined by the ridge line portion 22c, when the wire 20 inserted into the guide hole 22a comes into contact with the vicinity of the ridge line portion 22c, the sliding resistance is reduced. It turned out that it became undesirably large and hinders insertion work. 9 shows a cross-sectional view along the line AA in FIG. 8, and the chain line in FIG. 9 indicates the tapered surface (inner wall surface) of the guide hole 22a when cut along the line BB in FIG. ). Further, since the guide hole 23a of the lens holder 23 is longer in depth than the guide hole 22a of the support member 22, even if the guide hole 23a is formed in a quadrangular pyramid shape, the inclination of the ridge line portion becomes excessively gentle. There is nothing.

  The present invention has been made in view of the situation of the prior art as described above, and an object of the present invention is to provide an objective lens for an optical pickup that can position a wire in a guide hole of a support member with high accuracy and can easily insert the wire. It is to provide a driving device.

  In order to achieve the above object, the present invention includes a base member provided with a magnetic circuit for generating a magnetic flux, an objective lens for converging a light beam on a disk, and a coil crossing the magnetic flux. The attached lens holder, a plurality of conductive wires having one end connected to the coil and elastically supporting the lens holder, and a tapered guide hole through which each wire is individually inserted A support member made of a synthetic resin fixed to the base member and a back substrate fixed to the back side of the support member and connected to the other end of each wire, In the objective lens driving device of an optical pickup in which the wire can be positioned by a distal end portion, the guide hole has a cross-sectional shape of a base end portion having a relatively wide opening area, or a polygon having a circular shape or an octagon shape or more. With certain cross-sectional shape of the opening area is relatively narrow tip is square and set length of one side of the square slightly larger than the diameter of the wire.

  In this way, if the cross-sectional shape of the tip of the tapered guide hole of the support member through which the wire is inserted is a square that is small enough to circumscribe the wire, molding burrs that tend to occur at the four corners of the tip of the guide hole are likely to occur. However, it is possible to accurately position the wire at portions other than the four corners of the tip without impairing the insertion of the wire. Further, the cross-sectional shape of the base end portion of the tapered guide hole is formed in a circular shape or a polygonal shape of an octagon or more, and the entire shape of the guide hole is a substantially conical shape or a substantially polygonal pyramid shape of an octagonal pyramid or more. If the depth of the guide hole is short, the taper surface (inner wall surface) does not have a gentle slope, and the V-shaped groove is likely to fit with the wire. It is no longer defined near the ridgeline. Therefore, when the wire is inserted into the guide hole, the sliding resistance is not undesirably increased, and the wire insertion operation can be performed smoothly.

  In the above configuration, it is preferable that the inclination angle of the tapered surface of the guide hole is 59 degrees or more because sliding resistance when a wire is inserted into the guide hole can be sufficiently suppressed.

  In the objective lens driving device of the optical pickup according to the present invention, since the cross-sectional shape of the tip portion of the tapered guide hole of the support member through which the wire is inserted is a square that is small enough to be circumscribed by the wire, The wire can be accurately positioned without being affected by the molding burr. In addition, since the entire shape of the guide hole of the support member is substantially conical or substantially polygonal pyramid more than octagonal pyramid, sliding resistance is undesirably large when the wire is inserted into the guide hole. In addition, the wire insertion operation can be performed smoothly.

It is a top view which shows the objective lens drive device of the optical pick-up based on the embodiment of this invention. It is a top view of the whole optical pickup. It is a perspective view of the whole optical pickup. It is principal part explanatory drawing of the objective lens drive device shown in FIG. It is a front view of the guide hole of the support member shown in FIG. It is a front view which shows the modification of a guide hole. It is explanatory drawing which shows the attachment structure of the wire in the conventional objective lens drive device. It is a front view at the time of forming the guide hole of the support member of an objective lens drive device in the shape of a quadrangular pyramid. It is sectional drawing which follows the AA line of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. An actuator (objective lens driving device) 3 according to this embodiment has an appearance as shown in FIG. 1 and is incorporated in the optical pickup 1 shown in FIGS.

  First, the overall configuration of the optical pickup 1 will be described. The optical pickup 1 includes a chassis 2 made of aluminum or the like, an unillustrated light emitting / receiving unit fixed to one longitudinal end of the chassis 2, and an actuator 3 that is an objective lens driving device carried on the chassis 2. The cover 4 covers an optical component and a circuit board (not shown) arranged in the chassis 2 and a flexible wiring board 5 led out of the chassis 2. In use, the chassis 2 is linearly moved along a guide shaft (not shown) in the disc player, so that the optical pickup 1 can reciprocate in the radial direction of the disc. The light emitting / receiving unit is a unit composed of a semiconductor laser and a photodetector, and the light receiving / emitting unit is connected to an external drive circuit via a flexible wiring board 5. Further, a back substrate 10 (to be described later) of the actuator 3 is also connected to an external drive circuit via the flexible wiring substrate 5.

  The actuator 3 includes a synthetic resin lens holder 7 to which an objective lens 6 is attached, four wires 8 that elastically support the lens holder 7, and a synthetic resin made by inserting the proximal end side of each wire 8. Support member 9, a back substrate 10 fixed to the back surface of the support member 9, and a base member 12 on which the support member 9 and the magnetic circuit 11 are disposed. The magnetic circuit 11 is configured by combining a magnet and a yoke, and the base member 12 also serves as a part of the yoke.

  Coil (focusing coil and tracking coil) that crosses the magnetic flux generated by the magnetic circuit 11 is attached to the lens holder 7. These coils and the magnetic circuit 11 constitute electromagnetic driving means for driving the lens holder 7. The objective lens 6 is held on the upper surface of the lens holder 7, and the objective lens 6 is disposed at a position facing the recording surface of the disk.

  The wire 8 is made of a conductive metal wire, and its cross-sectional shape is a circle having a diameter of 0.11 mm. A total of four wires 8 are attached to each of the left and right sides of the lens holder 7 in total, and the lens holder 7 is elastically supported by these wires 8. That is, the fixed end side of each wire 8 is fixed to the support member 9 and the back substrate 10, and the free end side of each wire 8 supports the lens holder 7. As shown in FIG. 4, each wire 8 passes through the loose insertion hole 10 a of the back substrate 10 and the guide hole 9 a of the support member 9 and is inserted into the guide hole 7 a of the lens holder 7. Each wire 8 is soldered to a land portion (not shown) formed around the loose insertion hole 10 a on the back surface of the back substrate 10, and is focused at a point after passing through the guide hole 9 a of the lens holder 9. It is soldered to the lead-out portion 13 (see FIG. 1) of the coil or tracking coil.

  The loose insertion hole 10a of the back substrate 10 is formed in a cylindrical shape having a large diameter so that the wire 8 can be easily inserted. The guide hole 9a of the support member 9 is formed in a substantially conical shape as a whole. However, as shown in FIG. 5, the tip end portion 9b of the guide hole 9a is formed in a rectangular column shape that is small enough to be circumscribed by the wire 8. Has been. In order to secure a required length in a portion (effective portion) where the wire 8 is easily elastically deformed, the depth dimension of the guide hole 9a is set as short as 0.6 mm, and among these, the opening end 9c on the proximal end side is set. From the back to 0.5 mm is a substantially conical shape, and the remaining 0.1 mm is a small-diameter square columnar tip portion 9b. The guide hole 9a is formed in a circular shape with an opening end 9c on the base end side having a diameter of 0.7 mm, but the square columnar tip end portion 9b has a square cross-sectional shape, and the length of one side thereof is the diameter of the wire 8 ( 0.125 mm, which is slightly larger than 0.11 mm). Therefore, when the wire 8 is inserted through the distal end portion 9b of the guide hole 9a, the radial positioning of the wire 8 can be performed with high accuracy by the distal end portion 9b circumscribing the wire 8. In addition, since the molding burr produced in the square columnar tip portion 9b is almost limited to the four corners, the possibility that such a molding burr interferes with the wire 8 at the time of insertion is extremely low. Further, since the guide hole 9a can set the inclination angle of the substantially conical tapered surface (inner wall surface) to 60 degrees or more even if the depth dimension is as short as 0.6 mm, it interferes with the insertion work of the wire 8. The possibility of causing such a large sliding resistance is also low.

  Similarly to the guide hole 9 a of the support member 9, the guide hole 7 a of the lens holder 7 has a substantially conical shape as a whole, and is formed in a rectangular column shape having a small diameter so that only the tip portion can be circumscribed by the wire 8. Therefore, when the wire 8 is inserted into the distal end portion of the guide hole 7a, the radial positioning of the wire 8 can be performed with high accuracy by the distal end portion circumscribing the wire 8. However, since the guide hole 7a of the lens holder 7 has a longer depth than the guide hole 9a of the support member 9, it is extremely easy to set the inclination angle of the tapered surface (inner wall surface) of the guide hole 7a to be large. . Therefore, for the guide hole 7a of the lens holder 7, for example, even if the whole is formed in a substantially quadrangular prism shape, the inclination of the ridge line portion does not become excessively gentle.

  When the wire 8 is attached in the assembly process of the actuator 3, the wire 8 cut in advance to a predetermined length is inserted into the loose insertion hole 10 a of the rear substrate 10, and then the substantially conical surface of the guide hole 9 a of the support member 9. And is inserted through the tip 9b while guiding. Then, the wire 8 penetrating the guide hole 9 a is inserted into the tip portion while being guided by the substantially conical surface of the guide hole 7 a of the lens holder 7. After the wire 8 is inserted into the guide holes 9a and 7a and positioned in this manner, an adhesive (not shown) is inserted into the guide hole 9a and between the side of the lens holder 7 protruding from the tip of the guide hole 7a. The wire 8 is applied and fixed in a positioning state, and both ends of the wire 8 are soldered to the lead-out portion 13 of the coil and the land portion of the back substrate 10.

  The optical pickup 1 configured as described above records and reproduces information by converging the light beam emitted from the semiconductor laser with the objective lens 6 and irradiating the recording surface of the disk. Focus servo and tracking servo for controlling the beam spot diameter with respect to the recording surface of the disk are applied. That is, one end portion of each wire 8 is connected to the focus coil and tracking coil on the lens holder 7 side, and the other end portion of each wire 8 is connected to the back substrate 10, and the back substrate 10 connects the flexible wiring substrate 5. Therefore, by energizing the focus coil through a predetermined wire 8, an electromagnetic force is generated in the direction along the optical axis of the objective lens 6, and the lens holder 7 is moved in that direction. Accordingly, the focus correction of the objective lens 6 can be performed. Similarly, by energizing the tracking coil via another wire 8, it is possible to generate an electromagnetic force in a direction orthogonal to the optical axis of the objective lens 6 and drive the lens holder 7 in that direction. Tracking correction of the objective lens 6 is possible.

  As described above, in the actuator (objective lens driving device) 3 of the optical pickup 1 according to this embodiment, the cross-sectional shape of the distal end portion 9b of the guide hole 9a of the support member 9 through which the wire 8 is inserted is Since it is formed in a square that is small enough to circumscribe the wire 8, there is no risk that molded burrs that are likely to occur at the four corners of the tip 9b will impair the insertion of the wire 8, and the wires other than the four corners of the tip 9b 8 can be accurately positioned. Further, since the guide hole 9a has a substantially conical shape as a whole, the inclination of the tapered surface (inner wall surface) does not become so gentle even if the depth dimension is short, and the V-shaped groove can be fitted to the wire 8. Is not defined on the tapered surface. Therefore, when the wire 8 is inserted into the guide hole 9a, the sliding resistance does not increase undesirably, and the wire 8 can be inserted smoothly. Similarly, when the wire 8 inserted into the guide hole 9a of the support member 9 is inserted into the guide hole 7a of the lens holder 7, there is no possibility that the molding burr at the tip end portion of the guide hole 7 impairs the insertion of the wire 8. In addition, the wire 8 can be accurately positioned at portions other than the four corners of the tip portion. That is, in this embodiment, it is easy to insert the wire 8 into the guide holes 9a and 7a in the assembly process of the actuator 3, and the wire 8 is positioned with high accuracy by the guide holes 9a and 7a. Can do.

  In the above embodiment, the case where the entire shape of the guide hole 9a of the support member 9 is formed in a substantially conical shape has been described. However, the entire shape of the guide hole 9a is formed in a substantially octagonal pyramid shape as shown in FIG. It may be formed. Thus, even when the guide hole 9a is formed in a substantially octagonal pyramid shape, the inclination angle of the tapered surface (inner wall surface) can be set to 59 degrees or more, so that the wire 8 is inserted into the guide hole 9a. The sliding resistance at the time can be sufficiently suppressed. In this case as well, it is preferable that the cross-sectional shape of the tip end portion 9b of the substantially octagonal pyramid-shaped guide hole 9a is formed in a square shape small enough to circumscribe the wire 8. Moreover, even if the overall shape of the guide hole 9a is formed in a substantially N pyramid shape with N> 8, substantially the same effect as the above embodiment can be obtained.

1 Optical Pickup 2 Chassis 3 Actuator (Objective Lens Drive Device)
DESCRIPTION OF SYMBOLS 5 Flexible wiring board 6 Objective lens 7 Lens holder 7a Guide hole 8 Wire 9 Support member 9a Guide hole 9b Front-end | tip part 9c (Base end side) Open end 10 Back substrate 10a Free insertion hole 11 Magnetic circuit 12 Base member

Claims (2)

A base member provided with a magnetic circuit for generating magnetic flux, a lens holder that holds an objective lens for converging a light beam on a disk and a coil that crosses the magnetic flux is attached, and one end portion of which is attached to the coil Synthetic resin having a plurality of conductive wires connected and elastically supporting the lens holder, and a taper-shaped guide hole through which the wires are individually inserted and fixed to the base member An optical pickup that includes a support member made of metal and a back substrate fixed to the back side of the support member and connected to the other end of each wire, and the wire can be positioned by the tip of the guide hole. In the objective lens driving device,
The guide hole has a cross-sectional shape of a base end portion having a relatively large opening area and a circular shape or a polygon of an octagon or more, and a cross-sectional shape of a tip portion having a relatively small opening area is a square shape. An objective lens driving device for an optical pickup, wherein the length of one side of the optical pickup is set to a value slightly larger than the diameter of the wire.   2. The objective lens driving device for an optical pickup according to claim 1, wherein an inclination angle of the tapered surface of the guide hole is 59 degrees or more.

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