JP2015035243A - Objective lens actuator, and optical pickup having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an objective lens actuator and an optical pickup having the same for radiating so that heat generating in each coil is not conducted to the object lens, and controlling temperature gradient generating in the object lens.SOLUTION: An objective lens actuator comprises: a first relay part 331 and a second relay part 332 facing across a lens holder; and a cross-linking portion 333 cross-linked between the first relay part 331 and the second relay part 332, where a part of the cross-linking portion 333 is disposed between an objective lens and the lens holder. An optical pickup comprises the objective lens actuator.

Description

  The present invention relates to an objective lens actuator and an optical pickup including the same.

  The optical pickup is used when reading information from or writing information on an optical disk such as Blu-ray Disc (registered trademark) or DVD. An optical pickup generally includes a pickup base, a light source, and an objective lens actuator. The objective lens actuator includes an actuator base disposed inside a pickup base, an objective lens that focuses light emitted from a light source on an information recording surface of an optical disc, and a lens holder that holds the objective lens. The optical pickup reads information with light condensed by the objective lens and writes information with light condensed by the objective lens.

  The optical pickup needs to adjust the objective lens to an appropriate position so that the electric signal output by reading the light reflected from the optical disk can be obtained with the most appropriate value. Therefore, the objective lens is configured to be movable in at least the focus direction, the radial direction, and the tangential direction. The focus direction is a direction perpendicular to the information recording surface of the optical disc. The radial direction is the radial direction of the optical disc and is sometimes referred to as the tracking direction. The tangential direction is a direction parallel to the tangent to the information track of the optical disc.

  The lens holder for holding the objective lens is supported by a plurality of elastic wires so as to be swingable with respect to the actuator base. Such a lens holder includes a focus coil, a tracking coil, a tilt coil, and a conductive substrate. One end of each wire is fixed to the conductive substrate by soldering, and is electrically connected to each coil via the conductive substrate. Is done.

  Each wire vibrates according to the driving of the lens holder, so that the other end of each wire is inserted into the gel holder filled with the gel material and soldered to the wiring board attached to the gel holder in order to suppress the vibration. Fixed. With this configuration, current is supplied to each coil from the wiring board via each wire and the conductive substrate.

  By the way, when an electric current is supplied to each coil, each coil generates heat, so that the heat is transmitted to the objective lens through the lens holder, and there is a problem that a steep temperature gradient is generated in the objective lens. When a steep temperature gradient is generated in the objective lens, the objective lens is deformed to generate optical aberration, which may lead to deterioration in recording quality and reproduction quality. Therefore, various configurations for preventing heat transfer to the objective lens by radiating the heat generated in each coil have been proposed (for example, Patent Document 1).

Japanese Patent No. 4002084

  However, the optical pickup itself is an extremely small component, and it has been difficult to dissipate heat so that heat generated in each coil is not transmitted to the objective lens. Then, the heat that could not be dissipated was transferred to the objective lens, and a steep temperature gradient was generated in the objective lens.

  In view of the above-described problems, an object of the present invention is to provide an objective lens actuator that controls a temperature gradient generated in an objective lens and an optical pickup including the objective lens actuator.

  In order to achieve the above object, an objective lens actuator of the present invention includes an objective lens, a lens holder that holds the objective lens, a coil that is attached to the lens holder, and a conductive substrate that is conductive to the coil. The conductive substrate is bridged between the first relay unit and the second relay unit, and the first relay unit and the second relay unit facing each other with the lens holder interposed therebetween, and a part of the objective substrate and the lens holder And a bridge portion arranged between them.

  Further, in the objective lens actuator having the above-described configuration, the bridge portion dissipates heat of the coil that is transferred through the first relay portion and the second relay portion, and the first heat radiating portion and the first heat radiating portion. And a heat transfer section that is connected to the second heat radiating section and is in contact with the objective lens holder and transfers heat of the coil that is transferred through the first heat radiating section and the second heat radiating section to the objective lens. It is desirable to provide.

  Further, in the objective lens actuator having the above-described configuration, the connection part between the first relay part and the first heat radiation part and the connection part between the second relay part and the second heat radiation part are formed narrower than the first heat radiation part and the second heat radiation part. It is desirable to have done.

  In the objective lens actuator configured as described above, it is desirable that the first heat radiating portion and the connection portion between the second heat radiating portion and the heat transfer portion are formed narrower than the first heat radiating portion and the second heat radiating portion.

  In the objective lens actuator configured as described above, it is preferable that the heat transfer portion is formed in an annular shape and is in contact with a peripheral portion of the objective lens.

  In order to achieve the above object, an optical pickup according to the present invention includes the objective lens actuator.

  According to the present invention, when each coil generates heat, heat is transmitted to the first relay unit and the second relay unit included in the conductive substrate. The heat transmitted to the first relay unit and the second relay unit is further transmitted to the bridge portion that is bridged between the first relay unit and the second relay unit, which the conductive substrate has. Since a part of the bridge portion is disposed between the objective lens and the lens holder, the heat transferred to the bridge portion is transferred from the portion to the objective lens. With this configuration, heat generated in each coil is transferred to the objective lens while being controlled so as not to generate a sudden temperature gradient, so that the objective lens is prevented from being deformed by the sudden temperature gradient.

Top view showing configuration of optical pickup Schematic configuration diagram showing the configuration of the optical system of the optical pickup Top view showing the configuration of the objective lens actuator Front view showing the configuration of the objective lens actuator Left side view showing the configuration of the objective lens actuator Right side view showing the configuration of the objective lens actuator The perspective view which shows the structure of the conductive substrate of 1st Embodiment. The top view which shows the structure of the conductive substrate of 1st Embodiment. The right view which shows the structure of the conductive substrate of 1st Embodiment. The top view which shows the structure of the conductive substrate of 3rd Embodiment. The top view which shows the structure of the conductive substrate of 4th Embodiment.

<First Embodiment>
The objective lens actuator and optical pickup of the present invention will be described below with reference to the drawings. The following embodiment shows an example of an objective lens actuator and an optical pickup in order to embody the technical idea of the present invention, and the present invention is specified to the objective lens actuator and the optical pickup. The present invention is equally applicable to objective lens actuators and optical pickups of other embodiments included in the scope of claims.

  In this specification, in the XYZ coordinates shown in FIGS. 1 and 3 to 6, the X-axis direction is the left and right, the Y-axis direction is front and rear, and the Z-axis direction is up and down. Specifically, the right hand side is the right side and the left hand side is the left side with respect to the paper surface of FIG. Moreover, the upper side with respect to the paper surface of FIG. 1 is the back side, and the lower side is the front side. Also, the near side with respect to the paper surface of FIG. Note that the X-axis direction, the Y-axis direction, and the Z-axis direction can be rephrased as a tangential direction, a radial direction, and a focus direction, respectively.

  FIG. 1 is a top view showing the configuration of the optical pickup 1. FIG. 2 is a schematic configuration diagram showing the configuration of the optical system of the optical pickup 1. The optical pickup 1 includes a pickup base 2 made of a synthetic resin and an objective lens actuator 3 disposed inside the pickup base 2.

  Two bearing portions 2 a and 2 b are formed at the right end of the pickup base 2 so as to be spaced apart from each other, and one bearing portion 2 c is formed at the left end of the pickup base 2. In the optical disc apparatus, two horizontal guide shafts GS are arranged in parallel and spaced apart from each other. One guide shaft GS supports the bearing portions 2a and 2b, and the other guide shaft GS supports the bearing portion 2c. A driving force of a motor (not shown) is transmitted to the pickup base 2, and the pickup base 2 is supported by two guide shafts GS so as to be slidable in the axial direction of the guide shaft GS, in other words, in the Y-axis direction.

  On the objective lens actuator 3, members constituting the optical system of the optical pickup 1 are mounted. Hereinafter, the optical system of the optical pickup 1 will be described in detail. The optical pickup 1 of the present embodiment is provided so as to be able to read information and write information to a BD, DVD, and CD.

  The optical pickup 1 includes two types of optical systems. One of them is an optical system for BD, and the other is an optical system for DVD and CD (DVD / CD). These two types of optical systems are switched and used depending on the type of optical disk D (in this case, BD, DVD, or CD) on which information is read or written by the optical pickup 1. Hereinafter, the optical system for BD and the optical system for DVD / CD will be described separately.

  The optical system for BD includes a first laser diode 11, a diffraction element 12, a polarizing beam splitter 13, a first collimating lens 14, a quarter wavelength plate 15, a first raising mirror 16, a first objective lens 17, a first objective lens 17, and a first objective lens 17. A cylindrical lens 18 and a first photo detector 19 are provided.

  The first laser diode 11 is a light source that emits a light beam (laser light) having a wavelength of 405 nm. The light beam emitted from the first laser diode 11 is divided into a main beam and two sub beams by the diffraction element 12. The light beam emitted from the diffraction element 12 is reflected by the polarization beam splitter 13 and sent to the first collimating lens 14.

  The first collimating lens 14 can be moved in the optical axis direction (in the direction of the arrow shown in FIG. 2) by driving means (not shown), and the convergence / divergence state of the light beam incident on the first objective lens 17 is changed depending on the position. Change. The reason for this configuration is to enable correction of spherical aberration.

  The light beam (parallel light) emitted from the first collimating lens 14 passes through a quarter-wave plate 15 that functions as an optical isolator in cooperation with the polarization beam splitter 13 and is reflected by the first rising mirror 16. Then, the light enters the first objective lens 17. The first objective lens 17 focuses the incident light beam on the information recording surface Dr of the optical disc D.

  The light beam reflected by the optical disk D is transmitted through the first objective lens 17, then reflected by the first raising mirror 16, transmitted in the order of the quarter wavelength plate 15 and the first collimating lens 14, and then the polarization beam splitter 13. Also penetrates. The light beam that has passed through the polarization beam splitter 13 passes through the first cylindrical lens 18 having a function of correcting astigmatism, and is condensed on the light receiving surface of the first photodetector 19. The first photodetector 19 converts the incident optical signal into an electrical signal and outputs it. The electrical signal output here is processed by a signal processing unit (not shown) to become a reproduction signal, a focus error signal, a tracking error signal, or the like.

  Next, an optical system for DVD / CD will be described. The DVD / CD optical system includes a second laser diode 21, a half mirror 22, a second collimating lens 23, a second raising mirror 24, a second objective lens 25, a second cylindrical lens 26, and a second photo detector 27. .

  The second laser diode 21 is a two-wavelength laser that can switch and emit a light beam having a wavelength of 650 nm and a light beam having a wavelength of 780 nm. The light beam emitted from the second laser diode 21 is reflected by the half mirror 22, sent to the second collimating lens 23, and converted into parallel light.

  The light beam (parallel light) emitted from the second collimating lens 23 is reflected by the second raising mirror 24, enters the second objective lens 25, and is condensed on the recording surface Dr of the optical disc D.

  The light beam reflected by the optical disk D is transmitted through the second objective lens 25, then reflected by the second rising mirror 24, and transmitted through the second collimating lens 23 and the half mirror 22 in this order, thereby providing astigmatism. The light passes through the second cylindrical lens 26 and is collected on the light receiving surface of the second photodetector 27. The second photodetector 27 converts the incident optical signal into an electrical signal and outputs it. The electrical signal output here is processed by a signal processing unit (not shown) to become a reproduction signal, a focus error signal, a tracking error signal, or the like.

  The first objective lens 17 and the second objective lens 25 are moved in the focus direction, radial direction, and tilt direction by an objective lens actuator 3 (details will be described later). Thereby, focusing control, tracking control, and tilt control in the optical pickup 1 are possible.

  The objective lens actuator 3 will be described in detail below with reference to FIGS. FIG. 3 is a top view showing the configuration of the objective lens actuator 3. FIG. 4 is a front view showing the configuration of the objective lens actuator 3. FIG. 5 is a left side view showing the configuration of the objective lens actuator 3. FIG. 6 is a right side view showing the configuration of the objective lens actuator 3.

  The objective lens actuator 3 includes a ferromagnetic actuator base 31 disposed inside the pickup base 2, a lens holder 32 that holds the first objective lens 17 and the second objective lens 25, a conductive substrate 33, a permanent magnet 34, a gel holder (fixed). Member) 35, wiring board 36, and wire (rod-like elastic support member) 37.

  The actuator base 31 is formed with a through hole (not shown) through which a light beam passes substantially at the center. The lens holder 32 is arranged on the through hole. In the present embodiment, the first objective lens 17 and the second objective lens 25 are arranged in the tangential direction, but the present invention is not limited to this. For example, the first objective lens 17 and the second objective lens 25 may be arranged in the radial direction.

  The lens holder 32 is formed of a resin such as liquid crystal polymer (LCP) and holds the objective lenses 17 and 25. In the present embodiment, since the optical pickup 1 has two objective lenses 17 and 25, the lens holder 32 has two holders (see FIG. 2) so that the two objective lenses 17 and 25 can be held. Not shown). The two holding portions are respectively connected to optical path holes (not shown) through which the light beam passes, so that the light beam from the first laser diode 11 passes through the first objective lens 17 and the light from the second laser diode 21. The beam passes through the second objective lens 25.

  A focus coil, a tracking coil, and a tilt coil are attached to the wall surface of the lens holder 32 so as to face the permanent magnet 34. Each coil is wound in a substantially rectangular shape, and current is supplied from the wiring board 36 via the wire 37 and the conductive substrate 33. A focus coil (not shown) is disposed on the inner wall of the lens holder 32 along the inner wall. Further, one tracking coil (not shown) is attached to the outer wall of the lens holder 32 (side wall facing the permanent magnet 34) with an adhesive or the like. A tilt coil that is symmetrically arranged in the radial direction is attached to the lower side of the focus coil inside the lens holder 32. Each coil is wound in a substantially rectangular shape, and current is supplied from the wiring board 36 via the wire 37 and the conductive substrate 33.

  The conductive board 33 is a flexible printed board, and supplies the current supplied from the wiring board 36 to each coil. Here, the conductive substrate 33 will be described in detail with reference to FIGS. The conductive substrate 33 is attached to the front surface and the back surface of the lens holder 32 and includes a first relay portion 331 and a second relay portion 332 that are disposed to face each other in the radial direction with the lens holder 32 interposed therebetween. The first relay part 331 and the second relay part 332 are formed with a wiring pattern, and the upper two wires 37 are electrically connected to the focus coil via the first relay part 331 and the second relay part 332. The Further, the middle two wires 37 are electrically connected to the tracking coil via the first relay unit 331 and the second relay unit 332. The two lower wires 37 are electrically connected to the tilt coil via the first relay unit 331 and the second relay unit 332.

  The conductive substrate 33 further includes a bridge portion 333 that is bridged between the first relay portion 331 and the second relay portion 332. The bridge portion 333 is provided so as to cover a part on the upper surface side of the lens holder 32. The bridge part 333 has a first heat radiating part 334 whose one end is thermally connected to the first relay part 331, a second heat radiating part 335 whose one end is thermally connected to the second relay part 332, and a first heat radiating part at both ends. 334 and the 2nd thermal radiation part 335 are provided with the heat-transfer part 336 to which it connects thermally.

  The first heat dissipating part 334 has a first plate part 338 having a substantially trapezoidal shape as viewed from above, which is bent from the upper end part of the first relay part 331 through the first bent part 337 toward the second relay part 332 by approximately 90 degrees. A second plate having a substantially rectangular shape in front view that is bent approximately 90 degrees upward from the end portion of the first plate portion 338 (the end portion on the opposite side of the first bent portion 337) via the second bent portion 339. Part 340. By forming the horizontal width (length in the left-right direction) of the first bent portion 337 to be shorter than the horizontal width of the second bent portion 339, the first plate portion 338 has a substantially trapezoidal shape when viewed from above.

  The amount of heat transferred from the first relay portion 331 to the first plate portion 338 can be limited by forming the width of the first bent portion 337 shorter (thinner) than the first heat radiating portion 334. Further, the width of the second bent portion 339 is formed wider (thicker) than that of the first bent portion 337, and the surface areas of the first plate portion 338 and the second plate portion 340 are increased, so that the release from each plate portion is increased. The amount of heat transferred to the heat transfer section 336 can be reduced by increasing the amount of heat.

  The second heat dissipating part 335 has a substantially trapezoidal third plate part 342 that is bent substantially 90 degrees from the upper end part of the second relay part 332 toward the second relay part 332 via the third bent part 341; A fourth plate having a substantially rectangular shape in rear view that is bent approximately 90 degrees upward from the end portion of the third plate portion 342 (the end portion on the opposite side of the third bent portion 341) via the fourth bent portion 343. Part 344. By forming the lateral width (length in the left-right direction) of the third bent portion 341 shorter than the lateral width of the fourth bent portion 343, the third plate portion 342 has a substantially trapezoidal shape when viewed from above.

  The amount of heat transferred from the second relay portion 332 to the third plate portion 342 can be limited by forming the width of the third bent portion 341 shorter (thinner) than the second heat radiating portion 335. Further, the width of the fourth bent portion 343 is formed wider (thicker) than that of the third bent portion 341, and the surface areas of the third plate portion 342 and the fourth plate portion 344 are increased, thereby releasing from the respective plate portions. The amount of heat transferred to the heat transfer section 336 can be reduced by increasing the amount of heat.

  A fifth bent portion 345 and a sixth bent portion 346 that are substantially U-shaped in a side view are formed at the upper end portions of the second plate portion 340 and the fourth plate portion 344, respectively, and are thermally applied to the heat transfer portion 336. Connected. The fifth bent portion 345 and the sixth bent portion 346 are formed in a shape that holds the heat transfer portion 336 at a position lower than the upper ends of the second plate portion 340 and the fourth plate portion 344 with respect to the actuator base 31. The Similarly to the first bent portion 337 and the third bent portion 341, the fifth bent portion 345 and the sixth bent portion 346 are narrower than the first heat radiating portion 334 and the second heat radiating portion 335, respectively. By doing so, the amount of heat transferred from the second plate portion 340 and the fourth plate portion 344 to the heat transfer portion 336 can be limited.

  The heat transfer portion 336 is formed in an annular shape and is disposed between the objective lens 25 and the lens holder 32, and contacts each peripheral edge of the lower surface of the objective lens 25 and is transmitted to the heat transfer portion 336 via each portion. The heat generated from is transferred to the objective lens 25. Note that a copper foil is provided on the surface of the bridge portion 333 so that heat dissipation and heat transfer are efficiently performed.

  3 to 6, the wire 37 is an elastic member having conductivity. The lens holder 32 is supported by a wire 37 so as to be swingable with respect to the actuator base 31. A total of six wires 37 are provided in each of the three wires 37 approximately parallel to the first relay portion 341 side and the second relay portion 342 side with the lens holder 32 interposed therebetween. One end of each wire 37 is fixed to the first relay part 341 or the second relay part 342 by soldering and is electrically connected to each coil. The other end of each wire 37 passes through the gel holder 35 and is fixed to the wiring board 36 attached to the gel holder 35 by soldering. With this configuration, the wiring board 36 and each coil are electrically connected.

  The pair of permanent magnets 34 are symmetrically disposed on the actuator base 31 in the tangential direction so as to sandwich the lens holder 32. The yoke 310 is formed by bending a part of the actuator base 31 in order to efficiently use the magnetic flux generated by the permanent magnet 34. The pair of yokes 310 are formed so as to face the outer surface sides of the pair of permanent magnets 34, respectively, and the yoke 310 is magnetically attached to the outer surface side of the permanent magnet 34.

The yoke 310 formed on the gel holder 35 side of the yoke 310 (in the following description and drawings, the “yoke 310 formed on the gel holder 35 side” is referred to as “yoke 310a”) as described above. When the through hole is formed at the center of the base 31, the base 31 is formed by bending all or part of the portion that is penetrated (the penetrated portion). The other yoke 310 (“the other yoke 310”, that is, “the yoke 310 that is not the yoke 310a among the yokes 310” is referred to as “yoke 310b” in the following description and drawings) is the entirety of the end of the actuator base 31 or It is formed by bending a part.

  The gel holder 35 made of a resin molded product such as polycarbonate is disposed on the outer surface side of the yoke 310a (the side opposite to the side facing the lens holder 32 and the permanent magnet 34 in the yoke 310a). The gel holder 35 is filled with a gel material mainly composed of silicon. This gel material is obtained by injecting a low-viscosity gel material (sol) into the gel holder 35 and then curing the gel material by ultraviolet irradiation for a predetermined time. The gel holder 35 is provided with a plurality of through holes (not shown), and the vibration of the wire 37 accompanying the driving of the lens holder 32 is attenuated by inserting each wire 37 into each through hole.

  The wiring board 36 is fixedly disposed on the outer surface of the gel holder 35 (the surface of the gel holder 35 opposite to the surface facing the yoke 310). The wiring substrate 36 is a substrate that receives a signal from a control unit that controls the entire optical pickup 1 and supplies a current to each coil via each wire 37 and the conductive substrate 33.

  The wiring substrate 36 is fixed to the gel holder 35 using a thermosetting adhesive. However, in addition to fixing with an adhesive, screws may be fixed, or fixing with solder may be performed.

  According to this embodiment, when each coil generates heat, heat is transmitted to the first relay unit and the second relay unit included in the conductive substrate. The heat transmitted to the first relay unit and the second relay unit is further transmitted to the bridge portion that is bridged between the first relay unit and the second relay unit, which the conductive substrate has. Since a part of the bridge portion is disposed between the objective lens and the lens holder, the heat transferred to the bridge portion is transferred from the portion to the objective lens. With this configuration, heat generated in each coil is transferred to the objective lens while being controlled so as not to generate a sudden temperature gradient, so that the objective lens is prevented from being deformed by the sudden temperature gradient.

Second Embodiment
In the first embodiment, the conductive substrate 33 has a bridge portion 333 at a position corresponding to the objective lens 25 at the upper ends of the first relay portion 331 and the second relay portion 332, and the heat transfer portion 336 of the bridge portion 333 is provided. A configuration is adopted in which the heat generated by each coil is transferred between the objective lens 25 and the lens holder 32 and transferred to the objective lens 25. However, the present invention is not limited to this configuration, and the heat generated by each coil may be transferred to the objective lens 19.

  That is, in this embodiment, the bridge portion 333 is provided at a position corresponding to the objective lens 19 at the upper end of the first relay portion 331 and the second relay portion 332, and the heat transfer portion 336 is between the objective lens 19 and the lens holder 32. Arranged.

  According to the present embodiment, the same effects as those of the first embodiment can be obtained.

<Third Embodiment>
In the first embodiment and the second embodiment, the conductive substrate 33 has a bridge portion 333 at a position corresponding to the objective lens 25 or the objective lens 19 at the upper end of the first relay portion 331 and the second relay portion 332, The heat transfer section 336 of the bridge section 333 is arranged between the objective lens 25 or the objective lens 19 and the lens holder 32 so that heat generated by each coil is transferred to the objective lens 25. However, the heat generated by each coil may be transferred to the objective lens 19 and the objective lens 25.

  In the present embodiment, as shown in FIG. 10, the bridge portion 333 is provided at a position corresponding to the objective lens 25 and the objective lens 19 at the upper end portions of the first relay portion 331 and the second relay portion 332. The heat transfer section 336 included in one bridge 333 is disposed between the objective lens 25 and the lens holder 32, and the heat transfer section 336 included in the other bridge 333 is disposed between the objective lens 19 and the lens holder 32. Is done.

  In the present embodiment, the bridge portions 333 are not thermally connected on the upper surface side of the lens holder 32, but at least a part of the bridge portions 333 may be thermally connected.

  According to the present embodiment, the same effects as those of the first embodiment can be obtained.

<Fourth embodiment>
In the first to third embodiments, the first relay portion 331 and the second relay portion 332 are arranged to face each other in the radial direction with the lens holder 32 interposed therebetween. However, the present invention is not limited to this. It may be attached to both side surfaces (left side surface and right side surface) of the holder 32 so as to be opposed to each other in the tangential direction with the lens holder 32 interposed therebetween.

  As shown in FIG. 11, the conductive substrate 33 includes a bridge portion 347 that is bridged between the upper end central portion of the first relay portion 331 and the second relay portion 332. The bridge portion 347 includes a first heat radiating portion 348 whose one end is thermally connected to the first relay portion 331, a second heat radiating portion 349 whose one end is thermally connected to the second relay portion 332, and a first heat radiating portion 348. A first heat transfer unit 350 that is thermally connected to the other end and a second heat transfer unit 351 that is thermally connected to the other end of the second heat dissipation unit 349 are provided.

  The first heat radiating part 348 is a first plate part 353 having a substantially trapezoidal shape when viewed from above, bent from the upper end part of the first relay part 331 through the first bent part 352 toward the second relay part 332 by approximately 90 degrees, Side-view substantially rectangular second plate that is bent approximately 90 degrees upward from the end portion of the first plate portion 353 (the end portion on the opposite side of the first bent portion 352) via the second bent portion 354. Part 355. By forming the horizontal width (length in the front-rear direction) of the first bent portion 352 to be shorter than the horizontal width of the second bent portion 354, the first plate portion 353 has a substantially trapezoidal shape when viewed from above.

  The amount of heat transferred from the first relay portion 331 to the first plate portion 353 can be limited by forming the width of the first bent portion 352 shorter (thinner) than the first heat radiating portion 348. Further, the width of the second bent portion 354 is formed wider (thicker) than that of the first bent portion 352, and the surface areas of the first plate portion 353 and the second plate portion 355 are increased, so that the release from each plate portion is increased. The amount of heat transferred to the first heat transfer section 350 can be reduced by increasing the amount of heat.

  The second heat dissipating part 349 has a substantially trapezoidal third plate part 357 that is bent substantially 90 degrees from the upper end part of the second relay part 332 toward the first relay part 331 via the third bent part 356, A fourth plate having a substantially rectangular shape in side view that is bent approximately 90 degrees upward from the end of the third plate portion 357 (the end opposite to the third bent portion 356) via the fourth bent portion 358. Part 359. By forming the lateral width (length in the front-rear direction) of the third bent portion 356 shorter than the lateral width of the fourth bent portion 358, the third plate portion 357 has a substantially trapezoidal shape when viewed from above.

  The amount of heat transferred from the second relay portion 332 to the third plate portion 357 can be limited by forming the width of the third bent portion 356 shorter (thinner) than the second heat radiating portion 349. Further, the lateral width of the fourth bent portion 358 is formed wider than that of the third bent portion 356, and the surface areas of the third plate portion 357 and the fourth plate portion 359 are increased, thereby increasing the heat radiation from each plate portion. Thus, the amount of heat transferred to the second heat transfer section 351 can be reduced.

  A fifth bent portion 360 and a sixth bent portion 361 that are substantially U-shaped when viewed from the side are formed at the upper ends of the second plate portion 355 and the fourth plate portion 359, respectively. 2 is thermally connected to the heat transfer section 351. The fifth bent portion 360 and the sixth bent portion 361 have the first heat transfer portion 350 and the second heat transfer portion 351 with respect to the actuator base 31 from the upper ends of the second plate portion 355 and the fourth plate portion 359, respectively. Is formed in a shape that is held at a low position. Similarly to the first bent portion 352 and the third bent portion 356, the fifth bent portion 360 and the sixth bent portion 361 are narrower than the first heat radiating portion 348 and the second heat radiating portion 349. Thus, the amount of heat transferred from the second plate portion 355 and the fourth plate portion 359 to the first heat transfer portion 350 and the second heat transfer portion 351 can be limited.

  The first heat transfer part 350 and the second heat transfer part 351 are thermally connected by the connection part 362. In the present embodiment, a wiring pattern is formed on the bridge portion 347, and the first relay portion 331 and the second relay portion 332 are electrically connected. As a result, the control signal input to the first relay unit 331 via the wire 37 is also input to the second relay unit 332 via the bridge unit 347.

  The first heat transfer unit 350 and the second heat transfer unit 351 are formed in an annular shape, and are disposed between the objective lens 17 and the lens holder 32 and between the objective lens 25 and the lens holder 32, respectively. And it contacts the peripheral part of the lower surface of the objective lens 25. The heat generated in each coil is transferred to the first heat transfer unit 350 and the second heat transfer unit 351 via each unit, and is transferred from the first heat transfer unit 350 and the second heat transfer unit 351 to the objective lens 17 and the objective lens 25. Be heated.

  According to the present embodiment, the same effects as those of the first embodiment can be obtained after the conductive substrate is attached to both side surfaces of the lens holder.

  In this embodiment, the heat generated in each coil is transferred to the objective lens 17 and the objective lens 25. However, similarly to the first embodiment and the second embodiment, the heat is transferred to one of the objective lenses. It is good also as a structure which heats.

DESCRIPTION OF SYMBOLS 1 Optical pick-up 2 Pickup base 3 Objective lens actuator 11 1st laser diode 12 Diffraction element 13 Polarizing beam splitter 14 1st collimating lens 15 1/4 wavelength plate 16 1st raising mirror 17 1st objective lens 18 1st cylindrical lens 19 First Photodetector 21 Second Laser Diode 22 Half Mirror 23 Second Collimating Lens 24 Second Raising Mirror 25 Second Objective Lens 26 Second Cylindrical Lens 27 Second Photodetector 31 Actuator Base 32 Lens Holder 33 Conductive Substrate 34 Permanent Magnet 35 Gel Holder 36 Wiring board 37 Wire 310a, 310b Yoke 331 First relay part 332 Second relay part 333 Bridge part 334 First heat radiating part 335 Second heat radiating part 336 Heat transfer part

Claims (6)

An objective lens;
A lens holder for holding the objective lens;
A coil attached to the lens holder;
A conductive substrate conductive to the coil;
With
The conductive substrate includes a first relay portion and a second relay portion that are opposed to each other with the lens holder interposed therebetween,
A bridge portion that is bridged between the first relay portion and the second relay portion and part of which is disposed between the objective lens and the lens holder;
An objective lens actuator.   The bridge portion is connected to the first heat radiating portion and the second heat radiating portion, and the first heat radiating portion and the second heat radiating portion for radiating the heat of the coil that is transferred through the first relay portion and the second relay portion. The objective lens according to claim 1, further comprising: a heat transfer portion that contacts the objective lens holder and transfers heat of the coil that is transferred through the first heat dissipation portion and the second heat dissipation portion to the objective lens. Actuator.   The objective lens according to claim 2, wherein a connection portion between the first relay portion and the first heat dissipation portion and a connection portion between the second relay portion and the second heat dissipation portion are formed narrower than the first heat dissipation portion and the second heat dissipation portion. Actuator.   4. The objective lens actuator according to claim 2, wherein a connection portion between the first heat radiating portion and the second heat radiating portion and the heat transfer portion is formed narrower than the first heat radiating portion and the second heat radiating portion.   5. The objective lens actuator according to claim 1, wherein the heat transfer portion is formed in an annular shape and is in contact with a peripheral portion of the objective lens.   An optical pickup comprising the objective lens actuator according to any one of claims 1 to 5.

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