JP2014093103A - Objective lens drive device and optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an objective lens drive device that can stably drive a plurality of objective lenses, and to provide an optical pickup device employing the objective lens drive device.SOLUTION: An objective lens actuator 20 comprises: a lens unit 20 that holds objective lenses 113 and 114; circuit substrates 24 and 25 that are mounted to the lens unit 20; suspension wires 43 and 44 that support the lens unit 20; and solders 24d and 25d that connect the suspension wires 43 and 44 and the circuit substrates 24 and 25 to each other. The solders 24d and 25d are provided in the circuit substrates 24 and 25, respectively such that attachment positions of the solders 24d and 25d and a center-of-gravity G0 of the lens unit 20 align with each other in an arrangement direction of the objective lenses 113 and 114.

Description

  The present invention relates to an objective lens driving device and an optical pickup device using the same.

  Conventionally, compatible optical pickup devices that can handle a plurality of storage media have been developed. In such a pickup device, information is read from and written to the optical disk using laser beams having different wavelengths.

  In this type of optical pickup device, the required numerical aperture of the objective lens differs depending on the recording density of the corresponding optical disk. For example, an objective lens driving device that performs focus servo and tracking servo using a plurality of objective lenses to cope with optical disks of different standards is known (for example, Patent Document 1).

  In such an objective lens driving device, a coil is disposed on the movable portion side, and a magnet is disposed on the base. In this case, for example, by soldering a wire for supplying current to the movable part, a current is supplied to the coil arranged in the movable part.

JP 2009-277304 A

  In the objective lens driving device, since a plurality of objective lenses are arranged, the dimension of the movable portion increases in the arrangement direction of the objective lenses. In this case, due to variations in the size and weight of the parts arranged on the movable part, the center of gravity position of the movable part is in the direction in which the objective lenses are arranged, that is, the dimension of the movable part is larger than the predetermined design position. It becomes easy to displace. In particular, since the solder for supplying a current to the coil disposed in the movable part is heavy, variation in the coating amount and the coating position easily affects the displacement of the center of gravity.

  When the position of the center of gravity of the movable part changes from the design position, a deviation occurs between the power point of the driving force applied to the movable part by the focus coil and the position of the center of gravity of the movable part. If there is a deviation between the power point and the center of gravity in this way, resonance may occur in the movable part during focus servo, and the objective lens may not be driven stably. In particular, when a plurality of objective lenses are arranged, if resonance about an axis perpendicular to the arrangement direction of the objective lenses occurs, the objective lens is greatly displaced, and recording / reproduction characteristics are deteriorated.

  The present invention has been made in view of the above points, and an object thereof is to provide an objective lens driving device capable of stably driving a plurality of objective lenses and an optical pickup device using the same. To do.

A first aspect of the present invention relates to an objective lens driving device. The objective lens driving device according to this aspect includes a plurality of objective lenses, a movable portion that holds the objective lenses so that the plurality of objective lenses are arranged in a straight line, a coil that is attached to the movable portion, and the plurality of the plurality of objective lenses. Formed on the first side surface of the movable portion in a direction perpendicular to the direction in which the objective lenses are arranged, and formed on the second side surface of the movable portion opposite to the first side surface. A second connecting portion that is electrically conductive,
A plurality of first support members connected to the first connection portion, a plurality of second support members having conductivity and connected to the second connection portion, and the first support member And a first solder for electrically connecting the coil and a second solder for electrically connecting the second support member and the coil. The first and second solders are respectively attached so that the attachment positions of the first and second solders and the center of gravity of the movable part are aligned in the direction in which the plurality of objective lenses are arranged.

  A second aspect of the present invention relates to an optical pickup device. The optical pickup device according to this aspect converges the laser light emitted from the laser light source on the corresponding disk by the objective lens held by the objective lens driving device and the objective lens driving device according to the first aspect. And an optical system that guides the laser beam reflected by the disk to a photodetector.

  ADVANTAGE OF THE INVENTION According to this invention, the objective-lens drive device which can drive the several objective lens of light stably, and an optical pick-up apparatus using the same can be provided.

  The effects and significance of the present invention will become more apparent from the following description of embodiments. However, the following embodiment is merely an example for carrying out the present invention, and the present invention is not limited by the following embodiment.

It is a figure which shows the optical system of the optical pick-up apparatus which concerns on embodiment. It is a disassembled perspective view of the objective lens actuator which concerns on embodiment. It is a figure which shows the assembly process of the lens unit which concerns on embodiment. It is a figure which shows the assembly process of the lens unit which concerns on embodiment. It is a figure which shows the assembly process of the lens unit which concerns on embodiment. It is a figure which shows the structure of the lens unit which concerns on embodiment. It is a figure which shows the assembly process of the base unit which concerns on embodiment. It is a figure which shows the assembly process of the objective lens actuator which concerns on embodiment. It is a figure which shows the structure of the objective lens actuator which concerns on embodiment. It is a figure which shows the relationship between the solder which concerns on embodiment, and the gravity center position of a lens unit. It is a figure which shows the magnetic circuit of the objective lens actuator which concerns on embodiment. It is a figure explaining the resonance condition of the objective lens actuator which concerns on a comparative example. It is a figure explaining the resonance condition of the objective lens actuator which concerns on embodiment. It is a figure which shows the structure of the objective lens actuator which concerns on a comparative example.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the present embodiment, the semiconductor laser 101 corresponds to a “laser light source” recited in the claims. The optical member described in FIGS. 1A and 1B corresponds to an “optical system” described in the claims. The objective lens actuator 2 corresponds to an “objective lens driving device” described in the claims. The lens unit 20 corresponds to a “movable part” recited in the claims. The focus coils 22a to 22d correspond to “coils” recited in the claims. The circuit boards 24 and 25 correspond to “first and second circuit boards” recited in the claims. The solders 24d and 25d correspond to “first and second solders” recited in the claims. The suspension wires 43 and 44 correspond to a “support member” recited in the claims. However, the description of the correspondence between the above claims and the present embodiment is merely an example, and the invention according to the claims is not limited to the present embodiment.

  In the present embodiment, the present invention is applied to a compatible optical pickup device that is compatible with BD (Blu-ray Disc), DVD (Digital Versatile Disc), and CD (Compact Disc).

  1A and 1B are diagrams showing an optical system of an optical pickup device 1 according to the present embodiment. FIG. 1A is a plan view of an optical system in which the configuration on the disk side of the rising mirrors 111 and 112 is omitted, and FIG. 1B is a perspective view of the optical system after the rising mirrors 111 and 112 from the side. FIG.

  As shown in FIGS. 1A and 1B, an optical pickup device 1 includes a semiconductor laser 101, a half-wave plate 102, a semiconductor laser 103, a diffraction grating 104, a dichroic mirror 105, and a polarization beam. A splitter (PBS) 106, a front monitor 107, a collimator lens 108, a drive mechanism 109, a quarter wavelength plate 110, rising mirrors 111 and 112, objective lenses 113 and 114, and an astigmatism plate 115. And a photodetector 116. Each part of these optical systems is installed with respect to the housing of the optical pickup device 1 directly or via other members. The 1-beam method is applied to the BD optical system, and the conventional 3-beam method (inline method) is applied to the DVD optical system and the CD optical system.

  The semiconductor laser 101 emits laser light having a wavelength of about 405 nm (hereinafter referred to as “BD light”). The half-wave plate 102 adjusts the polarization direction of the BD light so that the polarization direction of the BD light is slightly shifted from the S polarization with respect to the PBS 106. The semiconductor laser 103 includes two laser elements 103a that respectively emit CD laser light (hereinafter referred to as “CD light”) having a wavelength of about 780 nm and DVD laser light (hereinafter referred to as “DVD light”) having a wavelength of about 650 nm. 103b. The semiconductor laser 103 is installed so that the polarization directions of the emitted DVD light and CD light are slightly deviated from the S polarization with respect to the PBS 106.

  FIG. 1C is a diagram when the semiconductor laser 103 is viewed from the beam emitting side. CD light and DVD light are emitted from the laser elements 103a and 103b, and a predetermined gap exists between the laser elements 103a and 103b.

  Returning to FIGS. 1A and 1B, the diffraction grating 104 divides the DVD light and the CD light into a main beam and two sub beams, respectively. The dichroic mirror 105 reflects BD light and transmits DVD light and CD light.

  Each of the BD light, DVD light, and CD light is transmitted through the PBS 106, and most of the light is reflected by the PBS 106. The front monitor 107 is irradiated with the BD light, DVD light, and CD light transmitted through the PBS 106. The front monitor 107 outputs a signal corresponding to the amount of received light. A signal from the front monitor 107 is used for emission power control of the semiconductor lasers 101 and 103.

  The collimator lens 108 converts BD light, DVD light, and CD light incident from the PBS 106 side into parallel light. The drive mechanism 109 moves the collimator lens 108 in the optical axis direction according to the control signal when correcting the aberration. The drive mechanism 109 includes a holder 109a for holding the collimator lens 108, and a gear 109b for sending the holder 109a in the optical axis direction of the collimator lens 108. The gear 109b is connected to the drive shaft of the motor 109c.

The BD light, DVD light, and CD light that have been converted into parallel light by the collimator lens 108 are incident on the quarter-wave plate 110. The quarter-wave plate 110 converts BD light, DVD light, and CD light incident from the collimator lens 108 side into circularly polarized light, and converts BD light, DVD light, and CD light incident from the rising mirror 111 side to the collimator. Conversion into linearly polarized light orthogonal to the polarization direction when entering from the lens 108 side. Thereby, the reflected light from the disk passes through the PBS 106 in the positive direction of the Z axis.

  The rising mirror 111 is a dichroic mirror that transmits BD light and reflects DVD light and CD light in a direction toward the objective lens 113 (Y-axis positive direction). The rising mirror 112 reflects the BD light in the direction toward the objective lens 114 (Y-axis positive direction).

  The objective lens 113 is configured to properly converge the DVD light and the CD light with respect to the DVD and the CD, respectively. The objective lens 114 is configured to appropriately converge the BD light on the BD. The objective lenses 113 and 114 are driven in the focus direction (Y axis direction) and the tracking direction (X axis direction) by the objective lens actuator 2 while being held by the lens holder 21.

  The configuration according to claim 6, wherein one of the two objective lenses 113 and 114 held by the lens holder 21 is an objective lens for BD and the other is an objective lens for CD and DVD. It is an example.

  The reflected light from the disk is converted into linearly polarized light that becomes P-polarized light with respect to the PBS 106 by the quarter-wave plate 110 and passes through the PBS 106. The PBS 106 is formed of a parallel plate having a polarizing film formed on one side, and is disposed so as to be inclined by 45 degrees with respect to the optical axes of BD light, DVD light, and CD light. The astigmatism plate 115 is also a parallel plate, and is disposed so as to be inclined with respect to the optical axes of BD light, DVD light, and CD light. The BD light, DVD light, and CD light reflected by the corresponding disk are transmitted through the PBS 106 and the astigmatism plate 115, so that predetermined astigmatism is introduced.

  On the light receiving surface of the photodetector 116, a plurality of sensors for receiving each light are arranged at positions where BD light, DVD light, and CD light are irradiated. Based on the output from each sensor, a reproduction RF signal, a focus error signal, and a tracking error signal are generated by a conventionally known method.

  FIG. 2 is an exploded perspective view showing the configuration of the objective lens actuator 2.

  Referring to FIG. 2, the objective lens actuator 2 includes a lens unit 20, a base unit 30, and a connection unit 40.

  The lens unit 20 includes the above-described objective lenses 113 and 114, the lens holder 21, focus coils 22a to 22d, tracking coils 23a to 23d, circuit boards 24 and 25, and protectors 26 and 27. The base unit 30 includes a base 31 and magnets 32a to 32d. The connection unit 40 connects the lens unit 20 and the base unit 30. The connection unit 40 includes a gel holder 41, a circuit board 42, suspension wires 43 and 44, and screws 45.

  With reference to FIGS. 3-8, the structure of each member of the lens unit 20 and the base unit 30 and an assembly process are demonstrated. 3 to 8, the direction of each member is reversed in the Z-axis direction with respect to FIG.

FIG. 3 shows the configuration of the lens holder 21 and the focus coil 22 for the lens holder 21.
It is a perspective view which shows the mounting | wearing process of a-22d and tracking coil 23a-23d.

  The lens holder 21 has a shape symmetric with respect to a plane parallel to the YZ plane. The lens holder 21 is made of a resin material or the like for weight reduction. The lens holder 21 is formed with a lens holding part 211 and coil holding parts 212a and 212b. The lens holding part 211 has a substantially rectangular parallelepiped outline.

  Each of the coil holding portions 212a and 212b includes a frame portion that extends from the side surface of the lens holding portion 211 in the positive and negative X-axis directions. The coil holding portion 212a is provided with a gap in which the focus coils 22a and 22b can be fitted in the positive direction of the X axis. Similarly, the coil holding part 212b is provided with a gap in which the focus coils 22c and 22d can be fitted in the negative X-axis direction. In addition, openings 212c to 212f are formed in the coil holding portions 212a and 212b at positions aligned in the vertical direction (Y-axis direction).

  On the side surfaces of the coil holding portions 212a and 212b on the negative side of the Z axis, hook-shaped tracking coil mounting portions 212g and 212i that protrude in the negative direction of the Z axis are formed. Further, hook-shaped tracking coil mounting portions 212h and 212j projecting in the positive Z-axis direction are formed on the side surfaces on the positive Z-axis side of the coil holding portions 212a and 212b, respectively.

  A flange portion 212k protruding in the X-axis negative direction is formed at a position slightly advanced in the Z-axis positive direction from the center of the side surface on the X-axis negative side of the coil holding portion 212a. The hook portion 212k is formed with three wire holes 212l for fixing three suspension wires 43 (see FIG. 2) described later to the lens holder 21. Further, a flange portion 212m protruding in the X-axis negative direction is formed at the left end (Z-axis positive direction) of the side surface of the coil holding portion 212a.

  Similarly, a collar portion 212n protruding in the X-axis positive direction is formed at a position slightly advanced in the Z-axis positive direction from the center of the side surface of the coil holding portion 212b. In the collar portion 212n, three wire holes 212o for fixing three suspension wires 44 (see FIG. 2) described later to the lens holder 21 are formed. Further, a flange portion 212p protruding in the X-axis positive direction is formed at the left end (Z-axis positive direction) of the side surface of the coil holding portion 212a.

  The focus coils 22a to 22d receive a magnetic flux from magnets 32a to 32d fixed to a base 31 described later, and a winding direction and a winding direction so that an electromagnetic driving force in the focus direction (Y-axis direction) is generated in the lens holder 21. The number has been adjusted. In addition, the focus coils 22a to 22d are wound so that the inner periphery has substantially the same outline as the openings 212c to 212f. In FIG. 3, the focus coils 22a and 22b are shown separated from each other, but in reality, the focus coils 22a and 22b are continuous. Similarly, the focus coils 22c and 22d are also continuous.

  The tracking coils 23a to 23d receive magnetic flux from magnets 32a to 32d fixed to the base 31 described later, and the winding direction and the winding direction so that an electromagnetic driving force in the tracking direction (X-axis direction) is generated in the lens holder 21. The number has been adjusted. In FIG. 3, for convenience, the tracking coils 23 a to 23 d are illustrated as being separated from each other, but are actually connected.

When the lens unit 20 is assembled, first, the focus coils 22a and 22b are inserted into the gap between the coil holding portions 212a from the X-axis negative side, and are bonded and fixed to the coil holding portions 212a. Similarly, the focus coils 22c and 22d are inserted into the gap between the coil holding portions 212b from the X axis positive side, and are bonded and fixed to the coil holding portions 212b. The tracking coils 23a to 23d are attached to the tracking coil attachment portions 212g to 212j, respectively. Thereby, the structure shown in FIG. 4 is completed.

  In this state, the three conducting wires at the start and end of the focus coils 22a and 22b and the start ends of the tracking coils 23a to 23d are positioned on the X-axis negative side of the lens holder 21. Further, the three conductive wires at the start and end of the focus coils 22c and 22d and the end of the tracking coils 23a to 23d are positioned on the X axis positive side of the lens holder 21.

  FIG. 4 is a perspective view showing a process of attaching the circuit boards 24 and 25 to the lens holder 21.

  The circuit boards 24 and 25 have a plate shape. Predetermined circuit patterns 24 a to 24 c are formed on the surface of the circuit board 24 (surface on the X axis negative side). Similarly, predetermined circuit patterns 25a to 25c are formed on the surface (surface on the positive side of the X axis) of the circuit board 25 (see FIG. 10).

  When the lens unit 20 is assembled, the X-axis positive side surface of the circuit board 24 abuts on the X-axis negative side surface of the coil holding portion 212a, and the Z-axis positive side surface of the circuit board 24 is in contact with the flange portion 212k. The circuit board 24 is disposed on the X-axis negative side surface of the coil holding portion 212a so as to abut on the Z-axis negative side surface. Similarly, the X-axis negative side surface of the circuit board 25 is in contact with the X-axis positive side surface of the coil holding portion 212b, and the Z-axis positive side surface of the circuit board 25 is the Z-axis of the flange portion 212n. The circuit board 25 is disposed on the X-axis positive side surface of the coil holding portion 212b so as to abut on the negative side surface. In this state, the circuit boards 24 and 25 are bonded and fixed to the lens holder 21. Thereby, part of the circuit boards 24 and 25 is positioned at the center of the side surface of the lens holder 21 in the Z-axis direction. Thus, the structure shown in FIG. 5 is completed.

  The configuration in which a part of the circuit boards 24 and 25 is positioned at the center of the side surface of the lens holder 21 is an example of the configuration according to claim 2.

  FIG. 5 is a perspective view showing a mounting process of the objective lenses 113 and 114 and the protectors 26 and 27 with respect to the lens holder 21.

  In the center of the lens holding portion 211, substantially circular lens mounting portions 211a and 211b are formed so as to be aligned in the Z-axis direction. On the X-axis negative side edge and the X-axis positive side edge of the lens holding part 211, protector mounting parts 211c and 211d, which are lowered by one step, are formed, respectively. A balancer 211e for adjusting the weight of the entire lens holder 21 is formed on the side surface of the lens holding portion 211 on the negative side of the Z axis. Further, the Y axis negative side of the lens holding portion 211 is hollow in order to accommodate the rising mirrors 111 and 112 (see FIG. 1B). An optical path hole 211f (see FIG. 2) for guiding the laser beam to the raising mirrors 111 and 112 (see FIG. 1B) is formed on the side surface of the lens holding portion 211 on the positive side of the Z axis.

  The lens mounting portion 211a includes a recess R1a for fitting the objective lens 113 and an opening R2a formed at the center of the recess R1a. In addition, four adhesive grooves R3a for applying an adhesive are formed around the recess R1a.

  The lens mounting portion 211b includes a concave portion R1b for fitting the objective lens 114, and an opening R2b formed at the center of the concave portion R1b. An adhesive groove R3b for applying an adhesive is formed around the recess R1b.

The protector mounting portion 211c is formed with flanges P1a and P1b that protrude in the positive Y-axis direction. Similarly, the protector mounting portion 211d has flanges P2a and P2 protruding in the Y-axis positive direction.
2b is formed.

  The protectors 26 and 27 are lens protection members having chamfered corners and a surface parallel to the XZ plane. The height in the Y-axis direction of the protectors 26 and 27 is slightly higher than the height in the Y-axis direction of the flanges P1a, P1b, P2a, and P2b. The protectors 26 and 27 are formed with flange portions 26 a and 27 a that protrude in the direction toward the lens holding portion 211, respectively. Adhesive grooves 26 b and 26 c are formed on the X-axis negative side surface of the protector 26. Similarly, adhesive grooves 27b and 27c (not shown) are formed on the surface of the protector 27 on the X axis positive side.

  When the lens unit 20 is assembled, the lower surface (the Y-axis negative side surface) of the objective lens 113 is fitted into the concave portion R1a of the lens mounting portion 211a. In this state, an adhesive is applied to the adhesive groove R3a, whereby the objective lens 113 is bonded and fixed to the lens holder 21. Similarly, the lower surface (surface on the Y-axis negative side) of the objective lens 114 is fitted into the recess R1b of the lens mounting portion 211b. In this state, an adhesive is applied to the adhesive groove R3b, whereby the objective lens 114 is bonded and fixed to the lens holder 21.

  Next, the protector 26 is fitted into the protector mounting portion 211c between the flange portions P1a and P1b and the lens holding portion 211. Then, an adhesive is applied to the bonding grooves 26 b and 26 c, and the protector 26 is bonded and fixed to the lens holder 21. Similarly, the protector 27 is fitted into the protector mounting portion 211d between the collar portions P2a and P2b and the lens holding portion 211 and is fixedly bonded. Thereby, the upper surfaces of the protectors 26 and 27 are positioned higher than the lens surfaces of the objective lenses 113 and 114. Therefore, the disc is prevented from coming into contact with the lens surfaces of the objective lenses 113 and 114. Thus, the lens unit 20 shown in FIG. 6 is completed. FIG. 6 is a perspective view showing the lens unit 20 in an assembled state.

  With the lens unit 20 assembled, the center of gravity G0 of the lens unit 20 in the in-plane direction of the XZ plane is positioned between the objective lens 113 and the objective lens 114. Specifically, the center of gravity G0 of the lens unit 20 is positioned at a substantially central position of the lens holder 21.

  Note that the configuration in which the balancer 211e is provided in the lens holder 21 in order to position the center of gravity G0 of the lens unit 20 at a substantially central position of the lens holder 21 is an example of a configuration according to claim 3. The configuration in which the center of gravity G0 of the lens unit 20 is positioned between the two objective lenses 113 and 114 is an example of a configuration according to claim 5.

  In the present embodiment, the focus coils 22a to 22d are arranged so as to be separated from each other at positions that are symmetrical with respect to the center of gravity G0, that is, at four diagonal positions of the lens holder 21. For this reason, when the electromagnetic drive force of equal magnitude is generated in the focus coils 22a to 22d, the position (power point) to which the resultant force of the electromagnetic drive force is applied is the center position of the lens holder 21, that is, the lens unit 20. Is the position of the center of gravity G0.

  FIG. 7A is a perspective view showing a process of attaching the magnets 32 a to 32 d to the base 31.

  The base 31 has a substantially rectangular outline in a top view. The base 31 is made of a magnetic material. The base 31 has a bottom 31a and walls 31b and 31c. The base 31 has a shape symmetric with respect to a plane parallel to the YZ plane.

In the bottom 31a, an opening 31d for accommodating the raising mirrors 111 and 112 (see FIG. 1B) is formed in the center. The wall 31c is formed with an optical path hole 31e for guiding the laser light to the raising mirrors 111 and 112 (see FIG. 1B). Further, as shown in the figure, square columnar yokes 31f to 31i are formed on the bottom 31a so as to protrude in the positive direction of the Y-axis. In plan view, the yokes 31f to 31i have a rectangular shape. The yokes 31f to 31i have substantially the same thickness and width.

  Magnet mounting portions 31j and 31l extending in the positive direction of the Z-axis are formed at both ends of the wall portion 31b. Similarly, magnet mounting portions 31k and 31m extending in the negative Z-axis direction are formed at both ends of the wall portion 31c. Two rectangular convex portions Ma are formed on the inner side surfaces of the magnet mounting portions 31j to 31m, respectively. In addition, columnar convex portions Mb are formed at positions facing the magnet mounting portions 31j to 31m of the bottom portion 31a.

  A collar 31n is formed at the upper end of the wall 31b. A screw hole 31o for fixing the base 31, the gel holder 41, and the circuit board 42 with screws 45 is formed in the collar portion 31n. Further, two holes 31p for engaging with the gel holder 41 are formed in the collar portion 31n.

  The magnets 32a to 32d have a substantially rectangular parallelepiped shape. The magnets 32a to 32d have the same shape and size as each other, and have the same magnetic force.

  When the base unit 30 is assembled, the side surfaces of the magnets 32a to 32d are in contact with the two convex portions Ma formed on the inner side surfaces of the magnet mounting portions 31j to 31m and the side surfaces of the wall portions 31c and 31b, respectively. The magnets 32a to 32d are installed on the base 31 so that the bottom surfaces of the magnets 32a to 32d are in contact with the cylindrical protrusions Mb formed on the bottom 31a. In this state, an adhesive flows into the gap between the magnets 32 a to 32 d and the base 31, and the magnets 32 a to 32 d are bonded and fixed to the base 31. Thereby, the base unit 30 shown in FIG. 7B is completed. In this state, the magnetic flux generated by the magnets 32a to 32d is incident on the yokes 31f to 31i facing each other. The distances between the magnets 32a to 32d and the yokes 31f to 31i facing the magnets 32a to 32d are the same.

  Thereafter, the openings 212 c to 212 f (see FIG. 3) of the lens holder 21 are passed through the yokes 31 f to 31 h of the base 31, and the lens unit 20 is positioned in the base unit 30. Thereby, the configuration shown in FIG. 8 is completed. Further, the gel holder 41 and the circuit board 42 shown in FIG. 2 are attached to the flange 31n, and the suspension wires 43 and 44 are further attached.

  Referring to FIG. 2, gel holder 41 has a shape in which the center is recessed in the negative Z-axis direction. At both ends in the X-axis direction of the gel holder 41, through holes 41a and 41b penetrating in the Z-axis direction are formed. In addition, two protrusions 41 c that engage with the two holes 31 p of the base 31 are formed in the recess of the gel holder 41. A screw hole 41 d is formed in the center of the concave portion of the gel holder 41. Further, a fitting portion 41e for fitting the circuit board 42 is formed on the surface of the gel holder 41 on the Z-axis negative side.

  The circuit board 42 has a plurality of steps along the shape of the fitting portion 41 e of the gel holder 41. At both ends of the circuit board 42, three wire holes 42 a for passing the three suspension wires 43 and three wire holes 42 b for passing the three suspension wires 43 are formed. A screw hole 42c is formed in the center of the circuit board 42.

  The suspension wires 43 and 44 are made of a material having excellent conductivity and flexibility such as phosphor bronze and beryllium copper.

  When the objective lens actuator 2 is assembled, one end of the suspension wires 43 and 44 is passed through the wire holes 42a and 42b of the circuit board 42 while the suspension wires 43 and 44 are passed through the through holes 41a and 41b of the gel holder 41. . Further, the circuit board 42 is fitted into the fitting portion 41 e of the gel holder 41. In this state, the three suspension wires 43 are passed through the three wire holes 212l (see FIG. 8) of the lens holder 21, and the three suspension wires 44 are passed through the three wire holes 212o (see FIG. 8) of the lens holder 21. Is done. Then, the gel holder 41 is pressed against the back surface of the flange 31 n of the base 31 so that the two protrusions 41 c of the gel holder 41 are fitted into the two holes 31 p (see FIG. 7) of the base 31. In this state, the screw hole 31o (see FIG. 7) of the base 31, the screw hole 41d of the gel holder 41, and the screw hole 42c of the circuit board 42 are combined, and the screw 45 causes the circuit board 42 to be attached to the gel holder 41 and the gel holder 41 to be attached. Screwed to the base 31.

  FIG. 9 is a perspective view showing a configuration of the objective lens actuator 2.

  As shown in FIG. 9, an adhesive is applied to the flange portions 212k, 212m, 212n, and 212p, and the suspension wires 43 and 44 are fixed to the lens holder 21. Thereafter, the suspension wires 43 and 44 are soldered to the circuit board 42 with solders 42d and 42e in a state where the lens holder 21 is stretched linearly so as to be parallel to the XZ plane and parallel to the XY plane. Thereby, the lens holder 21 is held in a state of floating on the base 31. Then, the gel buffer 41 is filled into the through holes 41a and 41b of the gel holder 41. As a result, vibrations to the optical pickup device 1 during focus servo and tracking servo are reduced.

  Then, in a state where the suspension wire 43 is fixed to the lens holder 21, the suspension wire 43, the lead wires of the focus coils 22a and 22b, and the lead wires of the tracking coils 23a to 23d are soldered to the circuit board 24. To be electrically connected. Similarly, with the suspension wire 44 fixed to the lens holder 21, the suspension wire 44, the lead wires at the start and end of the focus coils 22c and 22d, and the lead wires at the end of the tracking coils 23a to 23d are connected to the circuit board 25. Soldered and electrically connected.

  FIG. 10A is a partially enlarged view showing the periphery of the circuit board 25. FIG. 10B is a perspective view showing a cross section when the objective lens actuator 2 is cut along a plane parallel to the XY plane including the center of gravity G0 of the lens unit 20.

  As described above, predetermined circuit patterns 25 a to 25 c are formed on the circuit board 25.

  Lead wires at the ends of the tracking coils 23a to 23d are connected to the left end (Z-axis positive direction) of the circuit pattern 25a by solder 25f. The suspension wire 44 is connected to the right end (Z-axis negative direction) of the circuit pattern 25a by solder 25d. Although not shown, the circuit pattern 24a (see FIG. 4) is similarly connected to the circuit board 24 on the opposite side, the lead wires of the tracking coils 23a to 23d and the suspension wire 43 by solder. As a result, current is supplied to the tracking coils 23 a to 23 d via the suspension wires 43 and 44.

At the left end (Z-axis positive direction) of the circuit patterns 25b and 25c are focus coils 22c and 2c.
The lead wires at the start and end of 2d are connected by solder 25e. A suspension wire 44 is connected to the right ends (Z-axis negative direction) of the circuit patterns 25b and 25c by solder 25d. Further, although not shown, the circuit board 24 on the opposite side is similarly connected to the circuit patterns 24b and 24c (see FIG. 4), the lead wires of the focus coils 22a and 22b, the lead wires at the end and the suspension wire 44 by the solder 24e. The Accordingly, current is supplied to the focus coils 22a to 22d via the suspension wires 43 and 44.

  As shown in FIG. 10B, the solder 24d and the solder 25d are applied at positions aligned in the X-axis direction, and the center of gravity G0 of the lens unit 20 is positioned on a straight line connecting the solder 24d and the solder 25d. It has been.

  The configuration in which the solders 24d and 25d are applied so that the center of gravity G0 of the lens unit 20 is positioned on a straight line connecting the solders 24d and 25d is an example of the configuration according to claim 1. . Further, a configuration in which three suspension wires 43 and 44 are provided and three solders 24d and 25d are soldered to the circuit boards 24 and 25, respectively, is an example of a configuration according to claim 4.

  In this way, assembling of the objective lens actuator 2 is completed as shown in FIG.

  FIG. 11A and FIG. 11B are diagrams showing the configuration of the magnetic circuit of the objective lens actuator 2. FIG. 11A is a cross-sectional view of the objective lens actuator 2 cut along a cross section parallel to the YZ plane including the yokes 31g and 31f. FIG. 11B is a partial top view when the objective lens actuator 2 is viewed from above. In FIG. 11B, the members of the lens unit 20 other than the focus coils 22a to 22d and the tracking coils 23a to 23d are omitted for convenience. In FIGS. 11A and 11B, a black dot mark on the circle and a cross mark on the circle indicate the direction in which the current flows. A black dot mark on the circle indicates a direction toward the drawing reference person, and a cross mark on the circle indicates a direction away from the drawing reference person.

  Referring to FIGS. 11A and 11B, magnets 32a to 32d face yokes 31f to 31i, respectively. Therefore, the magnetic flux generated by the magnets 32a to 32d is mainly directed to the yokes 31f to 31i.

  The focus coils 22a to 22d are opposed to the N pole regions of the magnets 32a to 32d, respectively. When a current in the direction shown in FIG. 11A flows through the focus coils 22a and 22b, an upward (Y-axis positive direction) electromagnetic drive force acts on the focus coils 22a and 22b. Similarly, when a current in the direction shown in FIG. 11A flows through the focus coils 22c and 22d, an electromagnetic driving force in the upward direction (Y-axis positive direction) acts on the focus coils 22c and 22d.

  The number of turns of the focus coils 22a to 22d, the width and thickness of the yokes 31f to 31i, etc., so that the resultant force (power point) of the electromagnetic driving force generated in the focus coils 22a to 22d is positioned substantially at the same position as the gravity center G0 of the lens unit 20. Is adjusted. In the present embodiment, the balancer 211e (see FIG. 6) adjusts the weight of the lens unit 20 so that the center of gravity G0 of the lens unit 20 is positioned at the approximate center of the lens holder 21, and the focus coils 22a to 22d Since they are arranged at positions symmetrical with respect to the center of gravity G0, that is, diagonal positions on the lens unit 20, the number of turns of the focus coils 22a to 22d, the width and thickness of the yokes 31f to 31i, etc. It is almost the same. During focus servo, the same amount of current (focus servo signal) flows into the focus coils 22a to 22d.

  As shown in FIG. 11A, when a current is applied to the focus coils 22a to 22d, the lens holder 21 is displaced upward. On the other hand, when a current is applied to the focus coils 22a to 22d in the opposite direction, the lens holder 21 is displaced downward (Y-axis negative direction). In this way, the focus positions of the objective lenses 113 and 114 (see FIG. 9) are adjusted.

  The tracking coils 23a to 23d each have a central side of the lens holder 21 that faces the N-pole region of the magnets 32a to 32d, and the other side of the two sides aligned in the X-axis direction. It is positioned so as not to face the magnets 32a to 32d. Therefore, when a current in the direction shown in FIG. 11B flows through the tracking coils 23a to 23d, an electromagnetic driving force in the positive X-axis direction acts on the tracking coils 23a to 23d. Further, when a current is applied to the tracking coils 23a to 23d in the opposite direction, an electromagnetic driving force in the negative X-axis direction acts on the tracking coils 23a to 23d. The objective lenses 113 and 114 (see FIG. 9) are driven in the tracking direction by these electromagnetic driving forces.

  Here, in the present embodiment, since the objective lenses 113 and 114 are arranged in the Z-axis direction, the size of the lens holder 21 tends to increase in the Z-axis direction. For this reason, the position of the center of gravity of the lens unit 20 is likely to change in the Z-axis direction due to variations in dimensions and weights of the members constituting the lens unit 20. In particular, since solder is a metal and has a relatively large weight, variations in the coating position and coating amount greatly affect the weight balance of the lens unit 20.

  If the solder application position and the application amount vary, the center of gravity of the lens unit 20 may deviate from the position shown in FIG. 11A, that is, the position of the force point where the resultant electromagnetic driving force is applied in the focus direction. . If the position of the center of gravity of the lens unit 20 deviates from the focus point in the focus direction, vibration (pitching resonance) is likely to occur in the lens holder 21.

  Note that resonance that occurs around an axis parallel to the tracking direction (X-axis direction) is called pitching resonance, and resonance that occurs around an axis parallel to the focus direction is called yawing resonance.

  In the present embodiment, the lens holder 21 is supported by the suspension wires 43 and 44 at a substantially intermediate position in the direction in which the objective lenses 113 and 114 are arranged (Z-axis direction). , 114 may swing greatly, and the recording / reproducing characteristics may be greatly deteriorated.

  Therefore, in the present embodiment, in order to suppress the influence of pitching resonance due to variations in the amount of solder applied, the center of gravity G0 of the lens unit 20 is positioned on a straight line connecting the positions where the solder 24d and the solder 25d are applied. The circuit boards 24 and 25 are positioned substantially at the center of the lens holder 21.

  FIG. 12A to FIG. 12C are diagrams for explaining the influence of variations in the coating amount of the solders 24d and 25d in the case of the comparative example. 12 (a) to 12 (c), the gravity center position G0 of the lens unit 20 and the variation in the coating amount of the solder 24d and 25d when the variation in the coating amount of the solder 24d and 25d does not occur. The center of gravity G1 of the lens unit 20 when it occurs is shown.

  In the comparative example, as shown in FIG. 12A, the circuit boards 24 and 25 are positioned not at the approximate center of the lens holder 21 in the Z-axis direction but at the end on the negative side of the Z-axis. In this case, the solders 24d and 25d are positioned at positions away from the gravity center position G0 of the lens unit 20 in the Z-axis direction.

In the comparative example, for example, when the application amount of the solder 24d is larger than the normal application amount, the center-of-gravity position G1 of the lens unit 20 is the center-of-gravity position assumed at the time of design as shown in FIG. The direction is shifted from G0 toward the solder 24d. For this reason, as shown in FIG. 12C, the center of gravity position G1 of the lens unit 20 is aligned with the direction in which the objective lenses 113 and 114 are arranged (Z) from the force point at which the resultant electromagnetic driving force is applied in the focus direction (Y-axis direction). Axial) As a result, pitching resonance around an axis parallel to the X axis is likely to occur in the lens holder 21, and the optical axes of the objective lenses 113 and 114 may be greatly inclined due to this resonance.

  FIG. 13A to FIG. 13C are diagrams for explaining the displacement of the center of gravity when the application amounts of the solders 24d and 25d vary in the present embodiment. In FIG. 13A to FIG. 13C, variation in the coating amount occurs in the center of gravity position G0 of the lens unit 20 when there is no variation in the coating amount of the solder 24d and 25d and the solder 24d. The gravity center position G2 of the lens unit 20 in this case is shown.

  In the present embodiment, as shown in FIG. 13A, part of the circuit boards 24 and 25 is positioned at the center of the side surface of the lens holder 21 in the X-axis direction. The solders 24d and 25d are applied so as to be aligned on the X axis together with the gravity center position G0 of the lens unit 20.

  In the present embodiment, when the application amount of the solder 24d varies and the application amount of the solder 24d is larger than the normal application amount, the gravity center position G2 of the lens unit 20 is changed from the gravity center position G0 to the solder 25d. Sway in the direction toward However, in the present embodiment, since the gravity center G0 of the lens unit 20 and the application positions of the solders 24d and 25d are aligned in the X-axis direction, the displacement direction of the gravity center when the application amount of the solder 24d varies is As shown in FIG. 13B, the direction is the negative direction of the X axis. Accordingly, as shown in FIG. 13C, the position of the center of gravity G2 of the lens unit 20 is determined from the force point at which the resultant electromagnetic driving force is applied in the focus direction (Y-axis direction). (Z-axis direction) is not displaced. Therefore, in the case of the present embodiment, even if the application amount of the solders 24d and 25d varies, pitching resonance around an axis parallel to the X axis does not occur, and the objective lenses 113 and 114 are stably moved in the focus direction. Can be driven.

  In the present embodiment, since part of the circuit boards 24 and 25 is positioned so as to cover the center of the side surface in the X-axis direction of the lens holder 21, the rigidity of the entire lens holder 21 can be improved. . Thus, by improving the rigidity of the lens holder 21, it is possible to suppress resonance caused by the deflection of the lens holder 21 itself.

<Effect of Embodiment>
According to the present embodiment, the following effects can be achieved.

  The influence of pitching resonance due to variations in the amount of solder applied can be suppressed. Thereby, the objective lenses 113 and 114 can be stably driven in the focus direction.

In particular, in the present embodiment, the circuit board 24 is provided with three solders 24d, and the circuit board 25 is also provided with three solders 25d. As described above, since the number of locations where the solder is attached increases, the total weight of the solder increases. For this reason, the ratio of the weight of the solder to the weight of the lens unit 20 increases, and the influence of the solder on the weight balance of the lens unit 20 increases. However, according to the present embodiment, the locations where the solders 24d and 25d are attached and the center of gravity of the lens unit 20 are aligned in the direction in which the objective lenses 113 and 114 are aligned. Even if the application amount of 25d varies, the center of gravity of the lens unit 20 does not shift in the alignment direction of the objective lenses 113 and 114 with respect to a predetermined design position. Therefore, it is possible to effectively suppress the influence of pitching resonance due to variations in the amount of solder applied.

  In addition, since part of the circuit boards 24 and 25 is mounted so as to cover the center of the side surface of the lens holder 21, the rigidity of the entire lens holder 21 can be improved. Thereby, the resonance which arises when the lens holder 21 itself bends can be suppressed.

  Further, since the center of gravity G0 of the lens unit 20 is positioned at the substantially center position of the lens holder 21 by the balancer 211e, the objective lenses 113 and 114 can be driven in the focus direction and the tracking direction stably and smoothly. Can do.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications other than those described above can be made to the embodiments of the present invention.

  For example, in the above embodiment, the circuit boards 24 and 25 and the solders 24d and 25d are positioned at the approximate center of the lens holder 21, but the center of gravity position G0 of the lens unit 20 is as shown in FIG. If the circuit boards 24 and 25 are arranged so that the center of gravity G0 and the application positions of the solders 24d and 25d are aligned on the X-axis when the lens holder 21 is positioned at a position shifted from the center. good. Thereby, like the above embodiment, pitching resonance can be suppressed. In FIG. 14A, the balancer 211e is omitted.

  In this case, since the circuit boards 24 and 25 are not positioned at the center position of the side surface of the lens holder 21, the width of the circuit boards 24 and 25 in the Z-axis direction may be increased. If it carries out like this, the rigidity of the whole lens holder 21 can be improved like the said embodiment.

  In the above embodiment, the position of the solder 24d, 25d in the Z-axis direction and the position of the center of gravity G0 in the Z-axis direction are configured to match, but the position of the solder 24d, 25d in the Z-axis direction is It may be slightly deviated from the position of the center of gravity G0 in the Z-axis direction. For example, when the dimension of the lens holder 21 in the Z-axis direction is about 10 mm, the amount of deviation between the position of the solder 24d, 25d in the Z-axis direction and the position of the center of gravity G0 in the Z-axis direction is approximately 10 of this dimension. If it is about 0.2 mm of%, a pitching resonance can be suppressed compared with the comparative example of FIG.

  The first and second solders according to claim 1, wherein the attachment positions of the first and second solders and the center of gravity of the movable part are aligned in the direction in which the plurality of objective lenses are arranged. Are attached to the first and second circuit boards, ”as described above, the arrangement positions of the solders 24d and 25d and the center of gravity G0 of the lens unit 20 are the arrangement directions of the objective lenses 113 and 114. This includes the case of slight deviation in the (Z-axis direction).

  Further, in the above embodiment, the focus coils 22a to 22d are separately wound around the lens holder 21, but as shown in FIG. 22f may be wound. Furthermore, one focus coil may be disposed so as to surround the outer periphery of the lens holder 21.

Furthermore, in the above embodiment, the suspension wires 43 and 44, the focus coils 22a to 22d, and the tracking coils 23a to 23d are electrically connected by applying solder 24d and 25d to the circuit boards 24 and 25. However, the circuit boards 24 and 25 may be omitted, and the suspension wires 43 and 44, the focus coils 22a to 22d, and the tracking coils 23a to 23d may be directly electrically connected by solder. In this case, for example, the collar portions 212k and 212n are each divided into three in the vertical direction, and the end portions of the focus coils 22a to 22d and the end portions of the tracking coils 23a to 23d are respectively provided in the divided portions. It is wound. Thus, solder is attached between the suspension wires 43 and 44 where the ends of the focus coils 22a to 22d and the ends of the tracking coils 23a to 23d are wound. Also in this case, as in the above embodiment, the arrangement of each part is adjusted so that the attachment position substantially coincides with the position of the center of gravity of the lens unit 20 in the Z-axis direction.

  According to this configuration, since the circuit boards 24 and 25 are omitted, it is possible to reduce the number of components and to reduce the number of attached solder. However, when the circuit boards 24 and 25 are arranged as in the above embodiment, the rigidity of the entire lens holder 21 can be improved as described above, and resonance caused by the deflection of the lens holder 21 itself can be achieved. The effect that it can suppress can be show | played.

  In addition, the embodiment of the present invention can be variously modified as appropriate within the scope of the technical idea shown in the claims.

DESCRIPTION OF SYMBOLS 1 ... Optical pick-up apparatus 2 ... Objective lens actuator (objective lens drive device)
20 ... Lens unit (movable part)
211e ... balancer 22a-22d ... focus coil (coil)
23a-23d Tracking coil (coil)
24, 25 ... Circuit board (first and second circuit boards)
24d, 25d ... Solder (first and second solder)
212k, 212n ... collar (first and second coupling parts)
43, 44 ... Suspension wire (support member)

Claims (8)

A plurality of objective lenses;
A movable part that holds the objective lens such that the plurality of objective lenses are arranged in a straight line;
A coil mounted on the movable part;
A first connecting part formed on a first side surface of the movable part in a direction perpendicular to an arrangement direction of the plurality of objective lenses;
A second connecting portion formed on a second side surface of the movable portion opposite to the first side surface;
A plurality of first support members having electrical conductivity and coupled to the first coupling portion;
A plurality of second support members having electrical conductivity and coupled to the second coupling part;
A first solder for electrically connecting the first support member and the coil;
A second solder for electrically connecting the second support member and the coil;
The first and second solders are respectively attached so that the attachment positions of the first and second solders and the center of gravity of the movable part are aligned in the arrangement direction of the plurality of objective lenses.
An objective lens driving device. The objective lens driving device according to claim 1,
A first circuit board mounted on the first side surface and connected to the coil;
A second circuit board attached to the second side surface and connected to the coil,
The first solder and the second solder are attached to the first circuit board and the second circuit board, respectively.
An objective lens driving device. The objective lens driving device according to claim 2,
The first and second circuit boards are attached to the movable part so as to cover the centers of the first and second side surfaces of the movable part, respectively.
An objective lens driving device. In the objective lens drive device according to any one of claims 1 to 3,
The movable part is formed with a balancer for bringing the center of gravity closer to the center of the movable part.
An objective lens driving device. In the objective lens drive device according to any one of claims 1 to 4,
The first support member and the second support member are each arranged in three pieces,
The first solder and the second solder are attached three by three so as to correspond to the first support member and the second support member, respectively.
An objective lens driving device. In the objective lens drive device according to any one of claims 1 to 5,
Two objective lenses are attached to the movable part, and the center of gravity of the movable part is positioned between the two objective lenses.
An objective lens driving device. The objective lens driving device according to claim 6,
Of the two objective lenses, one is an objective lens for BD and the other is an objective lens for CD and DVD.
An objective lens driving device. The objective lens driving device according to any one of claims 1 to 7,
An optical system for converging laser light emitted from a laser light source onto a corresponding disk by the objective lens held by the objective lens driving device and guiding the laser light reflected by the disk to a photodetector; Prepare
An optical pickup device characterized by that.

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