JP2007080310A - Lens driving device and optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens driving device capable of moving a correction lens at a high speed when energized and not easily causing the position fluctuation of the correction lens when not energized; and also to provide an optical pickup device using the lens driving device. <P>SOLUTION: The lens driving device comprises: first and second guide shafts 4 and 5 provided in a base unit 1; a movable lens holder 2 supported movably along the first and second guide shafts 4 and 5; magnets 11a and 11b provided in the base unit 1; horizontal drive coils 14a and 14b provided in the movable lens holder 2, for receiving electromagnetic force in the longitudinal direction of the first and second guide shafts 4 and 5 by making a current flow; a vertical drive coil 13 provided in the movable lens holder 2, for receiving the electromagnetic force for generating rotary torque centering on the first guide shaft 4 by making the current flow; and a magnetic piece 15 provided in the movable lens holder 2, for receiving magnetic force for generating the rotary torque centering on the first guide shaft 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens driving device that moves the position of a correction lens, and an optical pickup device that uses this lens driving device as a correction lens actuator unit.

  In the optical pickup device, it is necessary to appropriately focus the light beam on the information layer of the optical disc. For this reason, in the optical pickup device, there is a proposal to move the correction lens between the light source and the objective lens in the optical axis direction so that the spherical aberration caused by the error in the thickness of the cover layer of the optical disk can be corrected (for example, Patent Documents 1 and 2).

JP 2004-103087 A (FIGS. 1 to 7) JP 2003-338069 A (FIGS. 1 to 5)

  By the way, the optical pickup device has a function of moving the correction lens at a high speed in order to quickly follow the difference in the thickness of the cover layer of the optical disc, and the correction lens has a function of disturbance vibration or the like even when there is no current. It is desirable to have a function of making the position difficult to change. However, none of the conventional optical pickup devices can achieve both of the above two functions.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a lens driving device that can move a correction lens at high speed when energized and that hardly changes the position of the correction lens when not energized, and an optical pickup device that uses this lens driving device.

  The lens driving device of the present invention holds a base member, first and second guide shafts provided in parallel to the base member, and a correction lens, along the first and second guide shafts. A movable lens holder supported in a movable manner, a magnet provided in the base member, and the movable lens holder provided in the movable lens holder in a magnetic field of the magnet, and the first and second guide shafts by passing an electric current. A first electromagnetic coil that receives an electromagnetic force in the longitudinal direction of the magnet, and an electromagnetic that is provided in the movable lens holder in a magnetic field of the magnet and that generates a rotational torque centered on the first guide shaft by passing an electric current. A second electromagnetic coil for receiving a force; and the movable lens holder provided in the magnetic field of the magnet. It is characterized by having a magnetic strip for receiving a magnetic force to cause the rotational torque about the shaft.

  An optical pickup device according to the present invention includes an objective lens for condensing a light beam on an information layer of a disc-shaped recording medium, a correction lens disposed in the light beam incident on the objective lens, and the correction lens for the light. And a lens driving device that moves in the axial direction.

  According to the present invention, there is an effect that the correction lens can be moved at a high speed when energized, and the function that the position variation of the correction lens hardly occurs due to disturbance vibration or the like when no energization can be achieved.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing a lens driving device 21 mounted on an optical pickup device according to Embodiment 1 of the present invention. 2 is a cross-sectional view taken along the line S2-S2 of the lens driving device 21 shown in FIG. 1 cut along a plane parallel to the first guide shaft 4 and the second guide shaft 5 through the center of the movable correction lens 9. is there. 3 is a cross-sectional view taken along line S3-S3 of the lens driving device 21 shown in FIG. 1 cut along a plane where the external shapes of the vertical driving coil 13 and the horizontal driving coils 14a and 14b provided in the movable lens holder 2 can be seen. . 4 is a cross-sectional view taken along line S4-S4 in which the lens driving device 21 shown in FIG. 1 is cut along a plane perpendicular to the first guide shaft 4 and the second guide shaft 5 through the center of the movable correction lens 9. FIG. is there.

  As shown in FIGS. 1 to 4, the lens driving device 21 includes a unit base 1, a movable lens holder 2, a fixed lens holder 3, a first guide shaft 4, a second guide shaft 5, A magnetic plate 6, a flexible printed circuit board 7, an optical sensor 8, a movable correction lens 9 held by the movable lens holder 2, a fixed correction lens 10 held by the fixed lens holder 3, magnets 11a and 11b, It has a vertical drive coil 13, horizontal drive coils 14 a and 14 b, and a magnetic piece 15.

  The unit base 1 is a base manufactured by resin molding, and a position reference (not shown) and a plane reference (not shown) for attaching the lens driving device 21 to the optical base (not shown) of the optical pickup device. ) And is attached to the optical base of the optical pickup device.

  The first guide shaft 4 and the second guide shaft 5 are attached to the unit base 1 in parallel with each other. The movable lens holder 2 is formed of a resin-molded member with good slidability and has a movable correction lens 9 mounted thereon. The movable lens holder 2 is configured such that the first guide shaft 4 is inserted into the through-hole 2d (shown in FIG. 4), and the second guide shaft 5 is engaged with the engaging portion 2e, so that the movable correction lens 9 is engaged. Are supported to be movable in the optical axis AX direction (x-axis direction in FIG. 1).

  The fixed lens holder 3 is fixed to the unit base 1. The fixed lens holder 3 has a fixed correction lens 10 mounted thereon. The optical axis of the fixed correction lens 10 fixed to the unit base 1 and the optical axis of the movable correction lens 9 incorporated in the movable lens holder 2 are assembled so as to coincide with each other.

  As shown in FIG. 4, the movable lens holder 2 includes a vertical driving coil 13 and horizontal driving coils 14a and 14b as a configuration for generating electromagnetic force. Further, fixed magnetic field generating magnets 11a and 11b and a magnetic plate 6 are attached to the unit base 1 so as to face the vertical driving coil 13 and the horizontal driving coils 14a and 14b. The magnets 11a and 11b are arranged so that different magnetic pole faces are arranged in the vertical direction (z-axis direction) in FIG. For example, the magnet 11a has an S pole on the side of the horizontal driving coil 14a, and the magnet 11b has an N pole on the side of the horizontal driving coil 14b. The vertical driving coil 13 is attached to a surface of the movable lens holder 2 facing the magnets 11a and 11b. The winding constituting the vertical drive coil 13 has a portion (reference numeral 13a in FIG. 3) extending in the horizontal direction (x-axis direction in FIG. 1) facing the magnet 11a, and a horizontal direction (in FIG. 3) facing the magnet 11b. 1 extending in the x-axis direction (reference numeral 13b in FIG. 3). The horizontal driving coils 14a and 14b are cylindrical coils, and the windings constituting the horizontal driving coil 14a extend in the vertical direction (z-axis direction in FIG. 1) facing the magnet 11a (reference numeral in FIG. 3). The horizontal drive coil 14b has a portion (reference numeral 14bh in FIG. 3) extending in the vertical direction (z-axis direction in FIG. 1) facing the magnet 11b.

  Power is supplied to the vertical driving coil 13 and the horizontal driving coils 14a and 14b attached to the movable lens holder 2 through the flexible printed board 7 having high flexibility.

  The movable lens holder 2 is provided with a protrusion 2c. The optical sensor 8 is fixed to the unit base 1, has a light emitting part (not shown) and a light receiving part (not shown), and is a protrusion 2 c interposed between the light emitting part and the light receiving part? The position of the movable correction lens 9 is detected depending on whether or not.

The vertical drive coil 13 includes a portion (reference numeral 13a in FIG. 3) extending in the horizontal direction (x-axis direction in FIG. 1) in the magnetic field of the magnet 11a and a horizontal direction (x-axis direction in FIG. 1) in the magnetic field of the magnet 11b. ) (A reference numeral 13b in FIG. 3), and by passing a current through the vertical drive coil 13, the vertical drive coil 13 is passed through the vertical direction of FIG. An electromagnetic force in a direction perpendicular to the central axis of the shaft 4 (z-axis direction) (electromagnetic force F _vcoil in FIG. 6 described later) acts.

The horizontal driving coils 14a and 14b have a portion (reference numeral 14ah in FIG. 3) extending in the vertical direction (z-axis direction in FIG. 1) in the magnetic field of the magnet 11a, and the horizontal driving coil 14b is in the magnetic field of the magnet 11b. Since it has a portion (reference numeral 14bh in FIG. 3) extending in the vertical direction (z-axis direction in FIG. 1), by passing a current through the horizontal driving coils 14a and 14b, the horizontal driving coils 14a and 14b An electromagnetic force (electromagnetic force F _hcoil in FIG. 5 to be described later) acts in the left-right direction in FIG. 2, that is, in the longitudinal direction (x-axis direction) of the first guide shaft 4.

  As shown in FIG. 4, the magnetic piece 15 is mounted inside the horizontal drive coil 14 b of the movable lens holder 2. The center of gravity of the movable part composed of the movable lens holder 2, the movable correction lens 9, the vertical drive coil 13, the horizontal drive coils 14 a and 14 b, and the magnetic piece 15 is made to coincide with the central axis of the first guide shaft 4. It is configured. The engaging portion 2e through which the second guide shaft 5 of the movable lens holder 2 is inserted is provided on the opposite side of the magnets 11a and 11b with the first guide shaft 4 interposed therebetween.

  The engaging portion 2e of the movable lens holder 2 that comes into contact with the second guide shaft 5 is a V-shaped groove formed of two surfaces that form an angle of about 90 degrees with each other. The locations where the two surfaces constituting the V-shaped groove come into contact with the second guide shaft 5 are the contact surface 2a and the contact surface 2b. The contact surface 2b of the movable lens holder 2 is configured in a member or shape that can obtain a higher friction coefficient than the contact surface 2a. The contact surface 2b of the movable lens holder 2 is made of, for example, a thin aluminum plate that has been subjected to surface hard alumite treatment. The contact surface 2b of the movable lens holder 2 is not limited to a thin aluminum plate subjected to surface hard anodizing treatment, and other configurations may be adopted.

FIG. 5 is a cross-sectional view taken along line S4-S4 of the lens driving device 21 shown in FIG. 1, and the electromagnetic force F _{hcoil in} the longitudinal direction (x-axis direction in FIG. 1) of the first and second guide shafts 4 and 5. It is a figure for demonstrating the generation | occurrence | production principle of.

In the vicinity of the surface of the south pole of the magnet 11a, a magnetic field in a direction substantially orthogonal to the south pole surface is generated toward the south pole. In the vicinity of the surface of the N pole of the magnet 11b, a magnetic field in a direction substantially perpendicular to the N pole surface is generated from the N pole toward the outside. When a current ih indicated by a vertical upward arrow in FIG. 5 is passed through the horizontal driving coil 14a and a current ih indicated by a vertical downward arrow in FIG. 5 is passed through the horizontal driving coil 14b, the left hand of Fleming In accordance with the law, the vertical force 14ah of the horizontal drive coil 14a and the vertical portion 14bh of the horizontal drive coil 14b are electromagnetic force F vertically upward (that is, in the x-axis direction in FIG. 1) from the plane of FIG. _hcoil occurs. As a result, the movable lens holder 2 moves in the x-axis direction in FIG. Further, by passing a current in the direction opposite to the current ih shown in FIG. 5 through the horizontal drive coils 14a and 14b, the vertical portion 14ah of the horizontal drive coil 14a and the vertical portion 14bh of the horizontal drive coil 14b are shown in FIG. Electromagnetic force is generated vertically downward from the paper surface on which 5 is drawn. As a result, the movable lens holder 2 moves in the reverse direction. Therefore, the position of the movable lens holder 2 can be controlled to move in the direction of the optical axis AX of the movable correction lens 9 by controlling the current value and direction of the current flowing through the horizontal driving coils 14a and 14b.

FIG. 6 is a cross-sectional view taken along line S4-S4 of the lens driving device 21 shown in FIG. 1, and the electromagnetic force F _{vcoil in} the vertical direction (z-axis direction in FIG. 1) of the first and second guide shafts 4 and 5. It is a figure for demonstrating the generation | occurrence | production principle of.

In the vicinity of the surface of the south pole of the magnet 11a, a magnetic field in a direction substantially orthogonal to the south pole surface is generated toward the south pole. In the vicinity of the surface of the N pole of the magnet 11b, a magnetic field in a direction substantially perpendicular to the N pole surface is generated from the N pole toward the outside. Here, when the current iv is supplied to the vertical drive coil 13, the horizontal portion 13a of the vertical drive coil 13 is directed upward (ie, z in FIG. 1) according to Fleming's left-hand rule. An axial electromagnetic force F _vcoil is generated, and an upward electromagnetic force F _vcoil illustrated in FIG. 5 (that is, the z-axis direction in FIG. 1) is generated in the horizontal portion 13 a of the vertical driving coil 13. By controlling the amount and direction of the current flowing through the vertical drive coil 13 in this way, the rotational torque of the movable lens holder 2 around the first guide shaft 4 can be controlled.

  7 is a cross-sectional view taken along line S4-S4 of the lens driving device 21 shown in FIG. 1. The driving force acting on the movable lens holder 2, the torque centered on the first guide shaft 4, and the movable lens holder 2 are shown. It is explanatory drawing which shows the drag which acts on the 2nd guide shaft 5 by contact surface 2a, 2b.

The movable lens holder 2, in addition to the electromagnetic force _{F Vcoil} generated by supplying a current to the electromagnetic force _{F Hcoil} and vertical drive coil 13 to generate I by flowing a current to the horizontal driving coil 14a, 14b, mainly A magnetic attractive force acting on the magnetic piece 15 acts by the magnet 11b. The magnetic piece 15 is disposed in the vicinity of the magnet 11b away from the first guide shaft 4 in the vertical direction of FIG. 7, and a magnetic attractive force acting on the magnetic piece 15 is always generated.

The pressing force _Fmp from the movable lens holder 2 to the first guide shaft 4 is always applied by the magnetic attraction force against the magnetic piece 15 by the magnet 11b. A torque T _mp (hereinafter referred to as “always torque”) centered on the first guide shaft 4 is constantly generated in the movable lens holder 2 by the magnetic attraction force on the magnetic piece 15 by the magnet 11b. Due to the current flowing in the vertical drive coil 13 and the electromagnetic force F _vcoil generated by the magnetic field generated by the magnets 11 a and 11 b, the movable lens holder 2 has a torque T _vcoil (hereinafter referred to as “drive torque”) centered on the first guide shaft 4. Say.) Occurs. A drag force N _vcoil acts on the second guide shaft 5 from the contact surface 2a of the movable lens holder 2 by the driving torque T _vcoil . A drag _Nmp acts on the second guide shaft 5 from the contact surface 2b of the movable lens holder 2 by the constant torque _Tmp .

In a non-energized state in which no current flows through the vertical drive coil 13, a magnetic attraction force with respect to the magnetic piece 15 by the magnet 11b acts on the movable lens holder 2, and a constant torque _{Tmp in the} clockwise direction in FIG. appear. For this reason, a drag force _Fmp acts on the first guide shaft 4 from the movable lens holder 2. In addition, a drag _Nmp acts on the second guide shaft 5 from the contact surface 2 b of the movable lens holder 2.

In the energized state in which the current iv shown in FIG. 6 is passed through the vertical driving coil 13, the movable lens holder 2 is _subjected to the first current by the current flowing through the vertical driving coil 13 and the electromagnetic force _Fvcoil generated by the magnetic field generated by the magnets 11a and 11b. A drive torque T _vcoil centering around the one guide shaft 4 is generated. Therefore, the direction to the drive torque _{T Vcoil} is generated to cancel the constant torque _{T mp} being generated continuously by the magnetic pieces 15. By controlling the amount and direction of the current flowing through the vertical drive coil 13, the constant torque T _mp due to the magnetic attraction force on the magnetic piece 15 is canceled out by the reverse drive torque T _vcoil , and the second guide shaft 5 The drag can be almost zero.

Further, by increasing the current supplied to the vertical drive coil 13 further from the second guide shaft 4 as the center drive torque T _Vcoil becomes larger than normally torque T _mp, contact surface 2a of the movable lens holder 2 A drag force N _vcoil acts on the second guide shaft 5.

  FIG. 8 is a diagram for explaining the stationary holding force of the movable lens holder 2 using the cross section taken along line S2-S2 of FIG.

Here, the static friction force at the contact surface between the first guide shaft 4 and the movable lens holder 2 is F _0, and the static friction force at the contact surface between the second guide shaft 5 and the movable lens holder 2 is F _i. The load when the movable part (mass M) including the correction lens 9, the movable lens holder 2, the driving coil, and the like receives disturbance (acceleration k × G) is defined as F _g . Note that k is an integer and G is the gravitational acceleration. Further, the friction coefficient and the contact area on the contact surface between the first guide shaft 4 and the movable lens holder 2 are μ ₀ and S ₀ , respectively, and the second guide shaft 5 and the first contact surface 2a of the movable lens holder 2 are in contact with each other. coefficient of friction and contact area, respectively, and mu _a and S _a. Furthermore, the second guide shaft 5 and the contact area and friction coefficient at the second contact surface 2b of the movable lens holder 2, respectively mu _b and S _b.

The static frictional forces F ₀ and F _i in a non-energized state where no current flows through the vertical drive coil 13 can be expressed by the following equations. Here, F _a shows the static friction force of the second guide shaft 5 and the contact surface of the movable lens holder 2 in the non-energized state.
F ₀ = μ ₀ × S ₀ × F _mp
F _i = F _a = μ _a × S _a × N _mp

Further, the force F _g acting on the movable lens holder 2 due to disturbance in a non-energized state where no current flows through the vertical drive coil 13 can be expressed by the following equation.
F _g = M × k × G

Here, the following conditional expression F ₀ + F _a > F _g
If the above is established, the movable lens holder 2 can remain stationary at a predetermined position on the first and second guide rails 4 and 5.

When the current iv shown in FIG. 6 is supplied to the vertical drive coil 13 to _make the direction of the drive torque T _vcoil opposite to the constant torque T _mp and the magnitude of the drive torque T _vcoil is the same as the constant torque T _mp , the movable lens The drag force of the holder 2 against the second guide shaft 5 is zero. The static frictional forces F ₀ and F _{i at} this time can be expressed by the following equations.
F ₀ = μ ₀ × S ₀ × F _mp
F _i = 0

Here, when the action of the driving force F _h horizontal driving coil 14a, by applying a current to 14b to the movable lens holder 2, the following conditional expression F _{0 <F h}
If is established, the movable lens holder 2 can be accelerated or decelerated and stopped in the direction along the first and second guide shafts 4 and 5, and the movable correction lens 9 can be moved to an arbitrary position.

Further, when the current flowing through the vertical driving coil 13 is further increased and the driving torque T _vcoil is made larger than the constant torque T _mp by the magnetic piece 15, the drag against the second guide shaft 5 by the movable lens holder 2 is on the contact surface 2b side. It becomes the drag of. The static frictional forces F ₀ and F _{i at} this time can be expressed by the following equations. Here, F _b indicates a static frictional force on the contact surface between the second guide shaft 5 and the movable lens holder 2.
F ₀ = μ ₀ × S ₀ × F _mp
F _i = F _b = μ _b × S _b × (N _vcoil −N _mp )

Here, when a driving force F _h is applied to the movable lens holder 2 by causing a current to flow through the horizontal driving coils 14a and 14b, the following conditional expression F ₀ + F _b <F _h
If is established, the movable lens holder 2 can be accelerated or decelerated in the direction along the first and second guide shafts 4 and 5, and the movable correction lens 9 can be moved to an arbitrary position.

As described above, in the lens driving device 21 mounted on the optical pickup device according to the first embodiment of the present invention, the second guide is provided by the contact surface 2b having a high friction coefficient of the movable lens holder 2 in a non-energized state. Since the drag force N _mg is applied to the shaft 5, a large static frictional force can be generated, and the position of the movable lens holder 2 can be stably held even when no power is supplied.

When the movable correction lens 9 is moved, a current is passed through the vertical drive coil 13 to generate a reverse drive torque T _vcoil that is always _equal to or greater than the torque T _mg , and the drag (N _vcoil −N _mg ) is reduced to a low friction coefficient. If the static frictional force is received by the contact surface 2a, the movable lens holder 2 can be moved to a desired position at a high speed by applying a position control current to the horizontal drive coils 14a and 14b.

  FIG. 9 is a diagram showing an optical system of the optical pickup device according to the first embodiment of the present invention. As shown in FIG. 9, divergent light emitted from the semiconductor laser 202 becomes parallel light by the collimator lens 203, enters the prism 205 through the diffraction grating 204, and is a unit of the lens driving device (spherical aberration correction device) 21. The light passes through the fixed correction lens 10 and the movable correction lens 9 formed on the base 1.

  The light that has passed through the lens driving device 21 changes its direction by 90 degrees by the mirror 201, then enters the objective lens actuator unit 100, passes through the objective lens 102, and is condensed on the information layer of the optical disc 101. The objective lens 102 accurately follows the movement of the information layer on the optical disc by the focus servo drive and the track servo drive of the objective lens actuator 100 including the objective lens holder 103 and the magnets 104a and 104b. The objective lens 102 is designed so as to be an optimum condensing spot when the outgoing convergent light passes through a transparent layer of a predetermined distance of the optical disc 101.

  When the thickness (distance) of the transparent layer changes due to an error in the cover layer thickness of the optical disk 102, the diameter of the focused spot increases and the recording / reproduction characteristics deteriorate. The influence of the error in the distance of the transparent layer acts as a spherical aberration on the condensing spot on the information layer of the optical disc, and the diameter of the condensing spot becomes large. However, the lens driving device 21 disposed before the objective lens is incident. When the movable correction lens 9 is moved in the optical axis direction, optical correction that cancels the spherical aberration corresponding to the error can be performed.

  The relationship between the spherical aberration that occurs when the thickness of the cover layer of the optical disc deviates from the reference value and the incident light that enters the objective lens in order to correct this spherical aberration is well known. No. 2003-338069) is disclosed in FIGS. 2 to 4. The reflected light from the information layer of the optical disc returns along the condensing path, branches off by the prism 205, enters the photodetector 210 through the condensing lens 207, the sensor lens 208, and the cylindrical lens 209, Servo signals and data signals are detected.

  As described above, according to the first embodiment, the movable correction lens 9 can be moved at high speed when energized, and the function that the position of the movable correction lens 9 does not easily change due to disturbance vibration or the like when no current is applied can be achieved. it can.

  Further, the spherical aberration generated due to the thickness error of the cover layer of the optical disk is moved in the optical axis direction according to the magnitude of the aberration, and the light beam incident on the objective lens 102 is diverged. The wavefront aberration on the information layer can be corrected and reduced by changing the state of the light flux to the side or the convergent light side.

  Further, by inserting the first guide shaft 4 into the movable lens holder 2 that can obtain a low friction coefficient and electromagnetically driving it, the lens can be moved at high speed and the time required for spherical aberration correction can be shortened. Further, the rotational torque due to the magnetic attractive force generated in the magnetic piece 15 of the movable part is used as a position holding force by pressing the lens holder against the guide shaft when no power is supplied. Further, the vertical component of the attractive force generated in the magnetic piece has an effect of preventing the movement vibration by applying pressure to the guide shaft of the bearing portion of the lens holder even during the movement.

  Further, the contact surface 2b having a high friction coefficient is used as the surface that receives the rotational torque by the magnetic piece 15, so that the static friction force is set to be large when the magnetic piece 15 is pressed against the contact surface 2b having a high friction coefficient by constant torque. The position of the lens holder can be reliably maintained when no power is supplied. Further, when the movable lens holder is moved, it is pressed against the contact surface having a low friction coefficient, so that the static frictional force is small and smooth movement can be performed with low friction.

  Further, the contact surface of the second guide shaft 5 that receives the rotational torque from the magnetic piece 15 is set to have a high friction coefficient surface, and the static friction force can be set large, so that the lens holder can be securely held in position when no power is applied. When moving the lens holder, it can move smoothly with low friction.

Embodiment 2. FIG.
FIG. 10 is a diagram showing an optical system of the optical pickup device according to the second embodiment of the present invention. 10, the same reference numerals are given to the same or corresponding components as those in FIG.

  The lens driving device 21 in the first embodiment is a beam expander correction device including two lenses, the fixed correction lens 10 and the movable correction lens 9, but the lens driving device in the second embodiment is a single lens driving device. It is a spherical aberration correction device that uses a collimating lens 203. The optical pickup device of the second embodiment is provided with a collimating lens 203 that can be moved in the optical axis direction in place of the movable correction lens 9 of the first embodiment, and a point that the fixed correction lens 10 is not provided. However, this is different from the optical pickup device of the first embodiment.

  In the optical pickup device of the second embodiment, the divergent light of the semiconductor laser 202 passes through the diffraction grating 204 and the prism 205 and passes through the collimator lens 203 formed on the unit base 1 of the spherical aberration correction device. The light that has passed through the spherical aberration correction device changes its direction by 90 degrees by the mirror 201, then enters the objective lens actuator unit 100, passes through the objective lens 102, and is condensed on the information layer of the optical disc 101.

  The reflected light from the information layer of the optical disc 101 returns along the condensing path, branches by the prism 205, passes through the sensor lens 208 and the cylindrical lens 209, and detects the servo signal and the data signal by the photodetector 210. .

  A method of correcting spherical aberration due to a change in the thickness of an optical disk substrate by a beam expander lens is an aberration correction method using a relay lens composed of a convex lens and a concave lens. A relay lens consisting of a convex lens and a concave lens is placed before entering the objective lens, and by changing the position of either the convex lens or the concave lens, the light incident on the objective lens is adjusted to be slightly divergent or convergent light. Thus, the spherical aberration of the beam incident on the optical disc from the objective lens is changed, and the spherical aberration generated in the optical disc information layer is canceled to generate a beam spot with less aberration. Such a system is disclosed in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2004-13087).

  As shown in FIG. 10, the optical pickup that constitutes the spherical aberration correction device using the collimator lens 203 has an advantage that the total length of the optical path is short and the number of optical elements constituting the optical pickup device is reduced. In addition, since the condensing optical system that collimates the collimator lens and enters the objective lens has the smallest number of optical components and the short optical path length, the optical pickup device can be made compact.

  In the second embodiment, points other than those described above are the same as those in the first embodiment.

Embodiment 3 FIG.
FIG. 11 is a longitudinal sectional view taken along a plane where the outer shape of the coil of the movable portion showing the different magnetic circuit of the spherical aberration corrector mounted on the optical pickup device according to Embodiment 3 of the present invention can be seen. In FIG. 11, the same or corresponding elements as those shown in FIG.

  The magnets 11a and 11b in the first embodiment are arranged with different polarities toward the coils 16a and 16b, but the magnet in the third embodiment is a single pole magnet (for example, two magnets in the first embodiment). 11a and 11b can be used as a magnet for generating a magnetic field for generating electromagnetic force.

  The movable lens holder 2 in the second embodiment is provided with vertical drive coils 16a and 16b and horizontal drive coils 17a and 17b having the shape shown in FIG. The vertical driving coils 16a and 16b are electromagnetic driving coils in which two ring-shaped coils wound parallel to the magnetic surface of an opposing magnet (not shown in FIG. 11) are arranged symmetrically in the vertical direction in FIG. Yes, by passing a current, an electromagnetic force in the vertical direction in FIG. 11, that is, in the direction perpendicular to the central axis of the first guide shaft 4 is generated.

  The horizontal drive coils 17a and 17b are electromagnetic drive coils wound in a horizontal cylindrical shape with respect to the magnetic surface of a magnet (not shown in FIG. 11). Electromagnetic force is generated in the longitudinal direction of the first guide shaft 4.

  The lens driving device according to the third embodiment is applicable to the first and second embodiments.

Embodiment 4 FIG.
In the description of the first embodiment, as shown in FIG. 4, the contact surfaces 2 a and 2 b between the second guide shaft 5 and the movable lens holder 2 are V-shaped grooves that form an angle of about 90 degrees with each other. Although the structure is used, the contact surfaces 2a and 2b may be parallel to each other, that is, surfaces opposite to each other with the second guide shaft 5 interposed therebetween.

Embodiment 5. FIG.
In the description of the first embodiment, the contact surface 2a between the second guide shaft 5 and the movable lens holder 2 shown in FIG. 7 is a molding surface made of a resin material capable of obtaining a low friction coefficient, and the contact surface 2b is a high friction material. The case where it was set as the thin aluminum board which performed the surface hard alumite process from which a coefficient is obtained was demonstrated. However, the contact surfaces 2a and 2b are molded surfaces made of a resin material that can obtain the same low friction coefficient, and the surface of the second guide shaft 5 that contacts the contact surface 2a can have a low friction coefficient, for example, a fluorine-coated surface. The surface of the second guide shaft 5 that is in contact with the contact surface 2b may be a solid stainless steel surface that has a high friction coefficient, for example, is subjected to a surface treatment that roughens the surface accuracy.

Embodiment 6 FIG.
In the first embodiment, the configuration in which the spherical aberration correction function of the optical pickup device is integrated on the unit base 1 of the lens driving device 21 has been described. However, the unit base 1 is omitted and the optical base of the optical pickup device is omitted. In addition, a guide shaft, a magnetic field circuit, a correction lens, and the like may be directly incorporated into the device.

Embodiment 7 FIG.
In the lens driving device of the seventh embodiment, the contact surface 2b of the movable lens holder 2 has the same curvature as the outer peripheral surface of the cylindrical second guide shaft 5, and has a large area with the outer peripheral surface of the second guide shaft 5. The contact surface 2b is different from the above-described embodiment in that the contact surface 2b is formed as a flat surface in the form of a concave surface having an arcuate cross section. Thus, by increasing the contact area S _b of the second guide-contacting surface 2b of the shaft 5 and the movable lens holder 2, it is possible to obtain a larger static friction force. In the seventh embodiment, points other than the above are the same as those in any of the first to sixth embodiments.

It is a perspective view which shows the principal part of the lens drive device by Embodiment 1 of this invention. FIG. 2 is a cross-sectional view taken along line S2-S2 of FIG. FIG. 2 is a cross-sectional view taken along line S3-S3 in FIG. FIG. 2 is a cross-sectional view taken along line S4-S4 of FIG. It is a figure for demonstrating the generation | occurrence | production principle of the horizontal electromagnetic drive force with respect to the movable lens holder in the lens drive device of FIG. It is a figure for demonstrating the generation | occurrence | production principle of the electromagnetic driving force of the orthogonal | vertical direction with respect to the movable lens holder in the lens drive device of FIG. It is a figure for demonstrating the torque with respect to the movable lens holder in the lens drive device of FIG. 1, and the force which acts on a 2nd guide shaft. It is a horizontal sectional view for demonstrating operation | movement of the lens drive device of FIG. It is a figure which shows the structure of the optical system of the optical pick-up apparatus by Embodiment 1 of this invention. It is a figure which shows the structure of the optical system of the optical pick-up apparatus by Embodiment 2 of this invention. It is a longitudinal cross-sectional view which shows the principal part of the lens drive device by Embodiment 3 of this invention.

Explanation of symbols

1 unit base, 2 movable lens holder, 2a, 2b movable lens holder contact surface, 3 fixed lens holder, 4 first guide shaft, 5 second guide shaft, 6 magnetic plate, 7 flexible printed circuit board, 8 optical sensor , 9 Movable correction lens, 10 Fixed correction lens, 11a, 11b Magnet, 13 Vertical drive coil, 14a, 14b Horizontal drive coil, 15 Magnetic strip, 16a, 16b Vertical drive coil, 17a, 17b Horizontal drive coil, 21 lens driving device (movable lens actuator), 100 objective lens actuator unit, 101 optical disk, 102 objective lens, 103 objective lens holder, 104a, 104b magnet, 201 mirror, 202 semiconductor laser, 203 collimating lens, 204 Diffraction grating, 205 prism, 206 optical power detector, 207 condenser lens, 208 sensor lens, 209 cylindrical lens, 210 optical sensor signal detector.

Claims (15)

A base member;
First and second guide shafts provided parallel to each other on the base member;
A movable lens holder that holds a correction lens and is movably supported along the first and second guide shafts;
A magnet provided in the base member;
A first electromagnetic coil provided in the movable lens holder in a magnetic field of the magnet and receiving an electromagnetic force in a longitudinal direction of the first and second guide shafts by passing an electric current;
A second electromagnetic coil that is provided in the movable lens holder in a magnetic field of the magnet and receives an electromagnetic force that generates a rotational torque about the first guide shaft by passing an electric current;
A lens driving device comprising: a magnetic piece that is provided in the movable lens holder in a magnetic field of the magnet and receives a magnetic force that generates a rotational torque about the first guide shaft. The first guide shaft is inserted through a through hole formed in the movable lens holder,
The lens driving apparatus according to claim 1, wherein the second guide shaft is supported by a first contact surface and a second contact surface formed on the movable lens holder.   The first contact surface and the second contact surface are located on opposite sides of a plane including the central axis of the first guide shaft and the central axis of the second guide shaft. The lens driving device according to claim 2, wherein   The lens driving device according to claim 3, wherein the first contact surface and the second contact surface form an angle of 90 ° with each other.   The lens driving device according to claim 3, wherein the first contact surface and the second contact surface are parallel to each other.   A second coefficient of friction between the first guide shaft and the second contact surface is greater than a first coefficient of friction between the first guide shaft and the first contact surface. 6. The lens driving device according to claim 2, wherein the lens driving device is configured as described above.   The lens driving device according to claim 6, wherein the second contact surface of the movable lens holder is made of an aluminum plate subjected to surface hard anodizing.   The range of contact with the second contact surface of the first guide shaft is an aluminum plate subjected to surface hard anodizing treatment or stainless steel subjected to surface treatment for reducing surface smoothness. 7. The lens driving device according to 6.   The lens according to claim 6, wherein a range in contact with the first contact surface of the first guide shaft and / or the first contact surface of the movable lens holder is a fluorine coating surface. Drive device.   The lens driving device according to claim 1, wherein the correction lens is a collimating lens.   11. The lens driving device according to claim 1, wherein the contact surface of the movable lens holder is a concave surface having an arc cross section having the same curvature as the outer peripheral surface of the second guide shaft. The movable lens holder has a protrusion;
The lens driving device according to claim 1, further comprising an optical sensor that detects the protruding portion.   The lens driving device according to claim 1, further comprising a flexible flexible printed circuit board having one end fixed in the vicinity of the through hole of the movable lens holder. An optical base;
An objective lens that is provided in the optical base and focuses a light beam on an information layer of a disc-shaped recording medium;
A correction lens disposed in a light beam incident on the objective lens;
An optical pickup device comprising: the lens driving device according to claim 1, wherein the correction lens is moved in an optical axis direction thereof.   The optical pickup device according to claim 14, wherein the optical base also serves as a base member of the lens driving device.

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