JP2009026380A - Objective lens driving device and optical pickup - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an objective lens driving device capable of focusing on a place where information of a storage medium is recorded with a minute movement (focal adjustment) without largely moving vertically an objective lens holding part. <P>SOLUTION: A lens holder 33 of the objective lens holding part 300 holds first and second objective lenses 31 and 32 through which light having wavelengths different from each other passes so that optical axes are parallel to each other and focal points are focused on the same plane S1 perpendicular to the optical axes. The objective lens holding part 300 is elastically suspended by suspension wires 41, 41 and 41 movably in the optical axis direction and a direction perpendicular to the optical axis direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an objective lens driving device for driving an objective lens and an optical pickup including the objective lens driving device.

  Conventionally, as an objective lens driving device used for an optical pickup, there is one shown in FIG. 5A (refer to Patent Document 1: FIG. 4 of Japanese Patent Application Laid-Open No. 8-22179). The objective lens driving device 200 includes the objective lens holding unit 53 and the objective lens holding unit 53 so that the optical axes are parallel to each other and the focal points are connected by two different planes S1 and S2 perpendicular to the optical axis. The first and second objective lenses 51 and 52 through which light having different wavelengths pass, an axis (not shown) for vertically moving and rotating the objective lens holding portion 53, and the objective And a drive unit (not shown) for driving the lens holding unit 53. The distance at which the first objective lens 51 is focused is d1, and the distance at which the second objective lens 52 is focused is d2.

As shown in FIG. 5A, the objective lens driving device 200 moves the objective lens holding unit 53 from the state in which the image (focus) of the first objective lens 51 is tied to the plane S1, as shown in FIG. It is moved by a distance d3 (d3 = d1−d2) and driven so that the image (focal point) of the second objective lens 52 is connected to the plane S1, as shown in FIG. 5B.
Japanese Patent Laid-Open No. 8-221799 FIG.

  However, in the conventional objective lens driving device 200, since the planes connecting the images (focal points) of the first and second objective lenses 51 and 52 are different planes S1 and S2, as shown in FIG. In addition, after the information on the same plane S1 is accessed by the first objective lens 51, as shown in FIG. 5B, the light having a wavelength different from the wavelength of the light passing through the first objective lens 51 passes. When accessing with the second objective lens 52, it is necessary to move the objective lens holding portion 53 by the distance between the plane S1 and the plane S2, that is, the difference d3 between the focal lengths d1 and d2.

  Therefore, in the objective lens driving device 200, when the first and second objective lenses 51 and 52 are accessed to information on the same plane, the moving distance of the objective lens holding portion 53 must be increased. was there.

  Further, in order to position the focal points of the first and second objective lenses 51 and 52 on the plane S1 or S2, when the objective lens holding unit 53 is slid along the axis by the driving unit, The objective lens holding portion 53 has a problem that it is difficult to drive smoothly due to the influence of friction.

  Further, since the objective lens holding portion 53 slides along the axis, a slight clearance between the axis and the objective lens holding portion 53 is likely to cause an inclination during vertical movement and rotation. It was difficult to increase accuracy.

  Accordingly, an object of the present invention is to finely adjust the objective lens holding portion when moving the focal points of the first and second objective lenses through which light of different wavelengths pass on the same plane, without greatly moving the objective lens holding portion up and down. It is an object of the present invention to provide an objective lens driving device capable of focusing on a place where information on a storage medium is recorded by performing a simple movement (fine focus adjustment).

  Another object of the present invention is to provide an objective lens driving device that can smoothly drive an objective lens holding portion without being affected by friction and can perform positioning with high accuracy.

In order to solve the above problems, the objective lens driving device of the present invention is:
An objective lens holding unit including a lens holder;
First and second objective lenses that are held by the lens holder and pass light of different wavelengths so that the optical axes are parallel to each other and the focal point is on the same plane perpendicular to the optical axis When,
The objective lens holding portion includes an elastic suspension member that elastically suspends the objective lens holding portion so as to be movable in the optical axis direction and a direction orthogonal to the optical axis direction.

  According to the objective lens driving device of the present invention, as can be seen from FIG. 1A, which is a schematic diagram showing one characteristic, the first and second objective lenses 31 and 32 have the same focal point S1. It is held by the lens holder 33 so as to be tied. Therefore, as shown in FIG. 1A, from the state in which the information on the plane S1 is accessed by the first objective lens 31, the second objective lens 32 as shown in FIG. 1B. Thus, even when accessing the information on the plane S1, it is not necessary to move the lens holder 33 largely (rough access).

  As described above, since there is no need to largely move the objective lens holding portion, the objective lens driving device can be reduced in size.

  Further, since the objective lens holding portion is suspended by the elastic suspension member, when the focal point connected by the first and second objective lenses is positioned, the elastic suspension member is elastically deformed for positioning. Thus, the focal point can be positioned without being affected by friction.

  Therefore, the objective lens holding part can be driven smoothly.

  Further, when the objective lens holding member is positioned by elastically deforming the elastic suspension member, since it is not affected by the clearance as in the prior art, the focus positioning accuracy can be increased.

In the objective lens driving device of one embodiment,
The objective lens holding part includes a balance weight.

  According to the objective lens driving device of this embodiment, since the objective lens holding portion includes a balance weight, the objective lens holding portion can be suspended in a balanced manner by the elastic suspension member.

  Therefore, it becomes easy to drive the objective lens holding portion, and the posture of the objective lens holding portion is stabilized.

Moreover, in the objective lens device of one embodiment,
The objective lens holding part is suspended on the elastic suspension member via a suspension part, and is perpendicular to a plane including the optical axis of the first and second objective lenses, and of the objective lens holding part The suspension is attached to the elastic suspension member in the vicinity of a plane passing through the center of gravity.

  According to the objective lens driving device of this embodiment, since the suspension portion is attached to the elastic suspension member in the vicinity of a plane passing through the center of gravity of the objective lens holding portion, the posture of the objective lens holding portion is stabilized. Thus, the inclination of the objective lens holding portion can be prevented, and the focus can be positioned with high accuracy.

  The suspension unit and the objective lens holding unit may be separate or integrated.

Further, in the objective lens driving device of one embodiment,
The elastic suspension member is attached to both sides of the objective lens holding portion located on both sides with respect to a plane passing through the optical axis of the first objective lens and the optical axis of the second objective lens.

  According to the objective lens driving device of this embodiment, since both sides of the objective lens holding part are supported by the elastic suspension member, the objective lens holding part can be supported stably and easily.

Further, in the objective lens driving device of one embodiment,
The outer surfaces of the first and second objective lenses are immersed more than the outer surface of the protective part provided in the objective lens holding part.

  According to the objective lens driving device of this embodiment, even if dust, dirt, foreign matter, or scratches are present on the surface of the storage medium, the first and second objective lenses are more effective than the outer surface of the protection unit. Since the outer surface is immersed, it is possible to prevent the storage medium or the like from coming into contact with the surfaces of the first and second objective lenses.

  Thus, since the first and second objective lenses are not damaged, the life of the objective lens driving device can be extended. Here, the outer surface of the first or second objective lens means a surface on the storage medium side.

Further, in the objective lens driving device of one embodiment,
The first and second objective lenses are made of different materials.

  According to the objective lens driving device of this embodiment, since the first and second objective lenses are formed of different materials, the first and second objective lenses are separated from each other in terms of the difference in focal length and the target. It is possible to optimize the lens according to the characteristics and cost of the lens such as light.

Further, in the objective lens driving device of one embodiment,
Each of the first and second objective lenses is a single lens.

  According to the objective lens driving device of this embodiment, since the first and second objective lenses are each constituted by a single lens, the cost can be reduced.

The optical pickup of the present invention is
The optical pickup includes the objective lens driving device.

  Since the optical pickup of the present invention includes the objective lens driving device, the focus positioning accuracy can be improved, and the size and weight can be reduced.

  According to the objective lens driving device of the present invention, when the focal points of the first and second objective lenses through which light having different wavelengths pass are connected on the same plane, the objective lens holding portion is not moved greatly up and down. It is possible to focus on a location where information on the storage medium is recorded with a slight movement (fine focus adjustment).

  Further, according to the objective lens driving device of the present invention, the objective lens holding portion can be driven smoothly without being affected by friction, and positioning can be performed with high accuracy.

  In addition, according to the pickup device of the present invention, the focus positioning accuracy can be improved, and the size and weight can be reduced.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 2 is a perspective view of the objective lens driving device of this embodiment.

  The objective lens driving device 100 includes an objective lens holding unit 300, a base mechanism 400 on which the objective lens holding unit 300 is mounted, and a suspension wire 41 as an elastic suspension member that elastically suspends the objective lens holding unit 300. The suspension wire 41 is provided with a drive unit 600 that is elastically deformed and driven.

  The objective lens holding unit 300 is a part of a lens holder 33 made of an insulating material such as resin that holds the first and second objective lenses 31 and 32 and a drive unit 600 attached to the lens holder 33. A track drive coil 35 and a focus drive coil 34, a holder substrate 40 made of an insulator as a suspension for suspending the lens holder 33 on the suspension wire 41, and a balance weight 43 (fixed to the lens holder 33) 3).

  The lens holder 33 holds the first and second objective lenses 31 and 32 so that the optical axes are parallel to each other and the focal point is on the same plane S1 perpendicular to the optical axis. Light having different wavelengths from a light source (not shown) passes through the first and second objective lenses 31 and 32.

  The first and second objective lenses 31 and 32 have different thicknesses and are formed of different materials. Furthermore, the first and second objective lenses 31 and 32 are each constituted by a single lens.

  As shown in FIG. 3, the distance from the surface of the first objective lens 31 to the focal point of the first objective lens 31 is d1, and from the surface of the second objective lens 32 to the focal point of the second objective lens 32. Is a distance d2.

  The first and second objective lenses 31 and 32 are arranged along the optical axis direction so that the surfaces of the first and second objective lenses 31 and 3 are connected to the same plane S1 whose focal points are perpendicular to the optical axis. The lens holder 33 holds each of them.

  As shown in FIG. 2, the lens holder 33 is suspended on suspension wires 41, 41, 41 as elastic suspension members via the holder substrate 40. Although not shown, the suspension wires 41, 41, 41 are electrically connected to the track drive coil 35 and the focus drive coil 34, which are part of the drive unit 600, to drive the track. Electric power can be supplied to the coil 35 and the focus drive coil 34. The holder substrate 40 and the lens holder 33 may be separate or integrated.

  The base mechanism 400 includes a base 36, a damping holder 37 attached to the base 36, and a fixed substrate 39 attached to the damping holder 37. A driving magnet 38 is fixed to the base 36.

  A set of three suspension wires 41, 41, 41 as the elastic suspension members elastically suspend each side portion of the lens holder 33 via the holder substrate 40. The suspension wire 41 is formed of an elastically deformable material, and enables the lens holder 33 to move in the optical axis direction and the direction orthogonal to the optical axis direction.

  One end of the suspension wire 41 is soldered to the side wall of the base 36, and the other end is soldered to the fixed substrate 39. Further, the central part of the suspension wires 41, 41, 41 is a plane perpendicular to the plane including the optical axes of the first and second objective lenses 31, 32 and passing through the center of gravity of the objective lens holding part 300. In the vicinity, the objective lens holding unit 300 is suspended in a well-balanced manner by being attached to the holder substrate 40. The suspension wires 41, 41, 41 are attached to both sides of the lens holder 33 located on both sides with respect to the plane passing through the optical axes of the first and second objective lenses 31, 32, and the objective lens holding portion 300 is well balanced and easily suspended.

  The drive unit 600 includes a track drive coil 35, a focus drive coil 34, and a drive magnet 38. The drive unit 600 elastically deforms the suspension wires 41, 41, 41, which are elastic suspension members, and drives the lens holder 33 so as to be movable in the optical axis direction and the direction orthogonal to the optical axis direction.

  A convex protective part P is provided on the outer peripheral edge of the lens holder 33 so that the outer surfaces of the first and second objective lenses 31 and 32 are immersed more than the surface of the protective part P. The protective part P is integral with the lens holder, but may be a separate body that is separately attached to the lens holder 33. Here, the outer surface of the first or second objective lens 31, 32 refers to the surface on the storage medium side.

  The protective part P is formed by intermittent protrusions provided along the outer peripheries of the first and second objective lenses 31 and 32.

  Although not shown, the protection unit may be a continuous annular protrusion along the outer periphery of the first and second objective lenses 31 and 32, and the first or second objective lens. It may be provided only on an objective lens whose surface is arranged at a distance close to the storage medium.

  Further, as shown in FIG. 3, the lens holder 33 has a balance weight 43 attached to the bottom B of the lens holder 33, for example, with an adhesive or the like, in order to adjust the weight balance of the objective lens holding unit 300. With the balance weight 43, the objective lens holding unit 300 is suspended from the suspension wires 41, 41, 41 in a balanced manner in the left and right and front and rear directions in FIG. 3, that is, parallel to the plane S1. .

  Next, the operation of the objective lens driving device 100 will be described.

  As shown in FIG. 3, the track drive coil 35 and the focus drive coil 34 are driven so as to focus on the surface on which the information of the storage medium 12 is recorded. Then, the suspension wire 41 is elastically deformed, and the lens holder 33 is moved in the optical axis direction and in the direction orthogonal to the optical axis to focus on a desired position.

  Accordingly, since the first and second objective lenses 31 and 32 are held by the lens holder 33 so that the focal points are on the same plane perpendicular to the optical axis, for example, the first information is on the same plane S1. Even when the information on the same plane S1 is accessed by the second objective lens 32 from the state of being accessed by the objective lens 31, the lens holder 33 does not need to be moved greatly.

  Thus, since it is not necessary to move the lens holder 33 largely, the objective lens driving device 100 can be miniaturized.

  In addition, since the objective lens holding unit 300 is suspended by suspension wires 41, 41, 41 which are elastic suspension members, when the focal point connected by the first and second objective lenses 31, 32 is positioned, the suspension is suspended. By positioning the wires 41, 41, 41 by elastic deformation, the focal point can be positioned without being affected by friction. Therefore, the objective lens holding unit 300 can be driven smoothly.

  In addition, since the suspension wire 41, 41, 41 is elastically deformed to position the lens holder 33, it is not affected by the clearance as in the prior art. Therefore, the positioning accuracy of the focal points of the first and second objective lenses can be increased.

  Further, since the lens holder 33 has the balance weight 43 attached to the bottom B, the objective lens holding part 300 can be suspended in a well-balanced state by the suspension wires 41, 41, 41 in parallel with the plane S1. Therefore, the objective lens holding unit 300 can be easily driven, and the posture of the lens holder 33 is stabilized.

  Further, since the holder substrate 40 is attached to the suspension wires 41, 41, 41 in the vicinity of the plane passing through the center of gravity of the objective lens holding unit 300, the posture of the lens holder 33 is stabilized, and the inclination of the lens holder 33 is increased. Therefore, the focal point can be accurately positioned.

  Further, since both side portions of the lens holder 33 are supported by the suspension wires 41, 41, 41, the lens holder 33 can be supported in a stable state and easily.

  Moreover, since the outer surfaces of the first and second objective lenses 31 and 32 are immersed more than the outer surface of the protective part P by providing the protective part P, the first or second objective is not provided. It is possible to prevent the storage medium 12 from coming into contact with the outer surfaces of the lenses 31 and 32. Therefore, since the first and second objective lenses 31 and 32 are not damaged, the life of the objective lens driving device 100 can be extended.

  Further, since the first and second objective lenses 31 and 32 are formed of different materials, the first and second objective lenses 31 and 32 should be optimal in accordance with the difference in focal length, the characteristics of the lens such as the target light and the cost. Can do.

  Furthermore, since the first and second objective lenses 31 and 32 are each constituted by a single lens, the cost can be reduced.

  Next, the configuration of the optical pickup including the objective lens driving device 100 will be described with reference to FIG.

  FIG. 4 shows a configuration diagram of one embodiment of the optical pickup device 110. The optical pickup device 110 records information on the surface of the storage medium 12 by irradiating the recording medium 12 such as a CD (compact disc) and a DVD (digital video disc) with a semiconductor laser light. To do. Alternatively, the reflected return light of the semiconductor laser light is detected to reproduce the information written on the surface of the storage medium 12. The optical pickup device 110 includes a semiconductor laser 1 as a light source, a collimating lens 2, an optical branching element 3 as a polarization branching element, a beam expanding element 4, a rising mirror 5, a first (second) mirror. A lens holder 33 that holds the objective lens 31 (32), a focus driving coil 34 that is a driving unit 600, a spot lens 9, a cylindrical lens 10, and a light receiving element 11 as a light receiving means are provided.

  Next, the operation of this optical pickup will be described.

  The divergent light from the semiconductor laser 1 is converted into a parallel beam by the collimating lens 2. The beam diameter of the parallel light beam is expanded by the beam expanding element 4 via the light branching element 3. The optical path of the expanded light is bent by the rising mirror 5, and then the light is condensed on the storage medium 12 by the light collecting unit 6. In the vicinity of the lens holder 33, the driving unit 600 moves the lens holder 33 in the optical axis direction and in a direction orthogonal to the optical axis, and focuses on the surface where the information of the storage medium 12 is stored. The reflected light from the storage medium 12 passes through the optical path opposite to the incident light, that is, the objective lens 6, the raising mirror 5, and the beam expanding element 4 in order, and then reflected by the light branching element 3. The reflected light is collected by the spot lens 9 and irradiated to the light receiving element 11 having a multi-divided light receiving section through the cylindrical lens 10. A recording signal and a servo signal are detected by the light receiving portion of the light receiving element 11.

  In the above embodiment, the objective lens driving device 100 including the lens holder 33 that holds the first and second objective lenses 31 and 32 has been described. However, the optical axes of three or more objective lenses are on the same plane. And the lens holder may hold the focal point on the same plane.

  Moreover, in the said embodiment, although the 1st and 2nd objective lenses 31 and 32 demonstrated what consists of a single lens, each may consist of a some combination lens in an optical axis direction.

  In the above embodiment, the lens holder 33 includes the balance weight 43. However, the position, shape, size, material, and attachment method of the balance weight 43 can be changed as appropriate. Further, the balance weight 43 may be integrally formed with the objective lens holding unit 300. Furthermore, the balance weight 43 may not be provided.

  In the embodiment, the suspension wire 41 is soldered to a plane that is perpendicular to the plane including the optical axes of the first and second objective lenses 31 and 32 and passes through the center of gravity of the objective lens holding unit 300. However, as long as the lens holder 33 can be suspended, the attachment method and the suspension position are not limited thereto.

  Further, although the suspension wire 41 has been described as supplying current to the track drive coil 35 and the focus drive coil 34, it may be an elastic suspension member that only performs suspension.

  Further, as the above-described elastic suspension member, the one in which each side surface of the objective lens holding portion 300 is suspended by the three suspension wires 41, 41, 41 has been described. However, if the objective lens holding portion can be suspended, the elastic suspension member The number, material, suspension position, and number of suspension positions are not limited to this.

  Moreover, in the said embodiment, although the 1st and 2nd objective lenses 31 and 32 demonstrated what was formed with a mutually different material, you may form with the same material.

  In addition, the objective lens holding unit 300 may include other components such as the track drive coil 35, the focus drive coil 34, the holder base 40, and the balance weight 43 as long as the lens holder 33 is included. Good.

FIGS. 1A and 1B are schematic views for explaining a main part of the objective lens driving device of the present invention. It is a perspective view which shows the objective lens drive device of one Embodiment of this invention. It is a partial cross section figure of the above-mentioned objective lens drive device. It is a figure which shows the structure of the optical pick-up provided with the objective-lens drive device of one Embodiment of this invention. 5A and 5B are schematic views for explaining a conventional objective lens driving device.

Explanation of symbols

Reference Signs List 31 first objective lens 32 second objective lens 33 lens holder 40 holder substrate 41 suspension wire 43 balance weight 100 objective lens driving device 110 optical pickup 300 objective lens holding unit S1 plane P protection unit

Claims (8)

An objective lens holding unit including a lens holder;
First and second objective lenses that are held by the lens holder and pass light of different wavelengths so that the optical axes are parallel to each other and the focal point is on the same plane perpendicular to the optical axis When,
An objective lens driving device comprising: an elastic suspension member that elastically suspends the objective lens holding portion so as to be movable in the optical axis direction and a direction orthogonal to the optical axis direction. The objective lens driving device according to claim 1,
The objective lens driving device, wherein the objective lens holding portion includes a balance weight. The lens driving device according to claim 1 or 2,
The objective lens holding part is suspended on the elastic suspension member via a suspension part,
The suspension part is attached to the elastic suspension member in the vicinity of a plane perpendicular to the plane including the optical axis of the first and second objective lenses and passing through the center of gravity of the objective lens holding part. An objective lens driving device. In the objective lens drive device according to any one of claims 1 to 3,
The elastic suspension member is attached to both sides of the objective lens holding portion located on both sides with respect to a plane passing through the optical axis of the first objective lens and the optical axis of the second objective lens. Objective lens driving device. In the objective lens drive device according to any one of claims 1 to 4,
2. An objective lens driving device, wherein the outer surfaces of the first and second objective lenses are submerged than the outer surface of a protective part provided in the objective lens holding part. In the objective lens drive device according to any one of claims 1 to 5,
An objective lens driving device, wherein the first and second objective lenses are made of different materials. In the objective lens drive device according to any one of claims 1 to 6,
An objective lens driving device, wherein each of the first and second objective lenses is a single lens.   An optical pickup including the objective lens driving device according to claim 1.

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