JP2006228310A - Objective lens driving device, optical pickup device, and optical disk drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an objective lens driving device capable of accurately preventing magnetic flux leakage, performing drive by a small current and being easily miniaturized. <P>SOLUTION: The objective lens driving device 10 is provided with an objective lens 11, a lens frame 12 for holding the objective lens, a suspension wire 17 as a support means for movably supporting the lens frame 12, a coil 13, and a driving means for electromagnetically moving the lens frame 12 by a magnet 14. The coil 13 is fixed to the lens frame 12 interposing a magnetic body plate 15A in-between, and the magnet 14 is arranged near the coil 13. A movable part 10A is constituted of the objective lens 11, the lens frame 12, the coil 13 and the magnetic body plate 15A, etc. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an objective lens driving device applied to an optical pickup device for recording, reproducing or erasing information with respect to an optical information recording medium such as an optical disc, a magneto-optical disc, a phase change optical disc or the like. The present invention also relates to an optical pickup device and an optical disk drive device provided with the objective lens driving device.

  In an optical disk drive device, a light spot is formed on a recording film of an optical disk to record, reproduce or erase information. The light spot is formed by condensing the light beam from the light source by the objective lens. An optical disk is a disc body, and a recording film vibrates in a radial direction or a direction perpendicular to the radial direction due to warpage or eccentricity. Therefore, an objective lens driving device is required as an actuator for finely adjusting the objective lens in the optical axis direction and the direction orthogonal to the optical axis direction in order to make the optical spot follow the recording film.

  In a conventional objective lens driving device (not shown), the objective lens is generally held by a bobbin, and the objective lens is supported by a plate spring having one end fixed to the bobbin so as to be movable in the optical axis direction. The other end of the leaf spring is fixed to an arm, and this arm is rotatably supported on a base by a predetermined shaft. A focus coil (focusing coil) is wound around the bobbin, and a flat track coil (tracking coil) is attached. In addition, a magnetic circuit composed of a permanent magnet and a yoke provides a driving force in the direction of the optical axis by energizing the focus coil and in the direction orthogonal to the optical axis by energizing the track coil. Each occurs. As described above, the objective lens driving device includes an objective lens, a holding member for the objective lens, a focus coil, a track coil, a magnetic circuit (magnetic path), and the like.

  Examples of the invention relating to the objective lens driving device include those disclosed in Patent Documents 1 to 3 below.

The invention described in Patent Document 1 aims to provide an objective lens driving device having a magnetic circuit with a simple structure and high efficiency, and has the following configuration.
A permanent magnet is provided on the side surface of the lens holder that holds the objective lens, a U-shaped yoke is fixed to the outer side of the magnetic pole surface of the permanent magnet, a track coil is fixed to the inner surface of the yoke, and further to the inner side thereof. The focus coil is fixed. By passing a current through the track coil, the lens holder moves in the track direction. By passing a current through the focus coil, the lens holder moves in the optical axis direction of the objective lens. Since the magnetic flux from the permanent magnet passes through the focus coil and the track coil, passes through the yoke, passes through the focus coil and the track coil arranged opposite to each other, and returns to the permanent magnet, magnetic flux leakage is reduced. Efficiency is improved.

  However, in the above structure, there is a problem that a large space is required because the movable part is enlarged.

The invention described in Patent Document 2 relates to an objective lens driving device that performs focusing by axial sliding and tracking by axial rotation, and has a simple structure and excellent temperature characteristics. An object of the present invention is to provide an apparatus having the following configuration.
A plurality of magnetic body pieces are attached in the vicinity of the end portion of the magnetic gap in the peripheral portion of the objective lens holding cylinder that is rotatably provided around the support shaft. Therefore, when the lens holding cylinder is rotated in the track direction, a force to pull into the magnetic gap due to the magnetic field due to the leakage magnetic flux acts on the magnetic piece protruding outside the end portion of the magnetic gap. And a magnetic circuit constitutes a magnetic spring corresponding to a conventional rubber spring. Therefore, the position in the tracking direction can be held with high accuracy, and the rubber spring can be eliminated and the size can be reduced.

  In this objective lens drive device, a magnetic piece is attached to the movable part side, but it does not use the magnetic force of the magnetic circuit of the actuator effectively, but uses the attractive force generated between the magnetic circuit and the magnetic piece. The objective is to form a magnetic spring and maintain the neutral position in the tracking direction of the objective lens accurately without increasing the size of the device, so it is mentioned that the magnetic material is placed between the lens frame and the coil. Not. Also in the explanatory view, a magnetic body is disposed between the coil and the magnet.

  An object of the invention described in Patent Document 3 is to improve drive sensitivity by providing a prevention means for preventing leakage of magnetic flux from an open portion of a magnetic circuit in an objective lens driving device. In that configuration, the cover is covered to protect the movable part against an impact from the outside, and on the inner surface of the cover, the part where the magnetic circuit leaks, that is, the upper part of one magnet and the yoke, the other magnet and When an iron piece with good magnetic conductivity is attached so as to straddle the upper part of the yoke and the cover is covered with the objective lens driving device, the leakage magnetic flux of the magnetic gap passes through the inside of the iron piece. With such a configuration, the magnetic circuit is closed by simply covering the objective lens driving device with the cover, and the leakage magnetic flux from the magnetic gap can be reduced.

  In this objective lens driving device, a magnetic material is disposed on the cover to reduce the leakage magnetic flux, but the magnetic material is not attached to the movable part to form a closed magnetic path.

  As shown in FIGS. 1 and 2, in an objective lens driving device, when a magnet or coil is attached to a U-shaped or U-shaped yoke to form a closed magnetic circuit, magnetic flux leakage is reduced and the efficiency of the magnetic circuit is improved. Therefore, even with the same power, a larger thrust can be obtained. FIG. 1 is a perspective view showing a conventional objective lens driving device when the magnetic circuit is a closed magnetic circuit, and FIG. 2 is an exploded perspective view of FIG.

  However, in the objective lens driving device 100, since a space is required to pass the yoke 102 through the lens frame (movable part) 101, the lens frame 101 is increased in size. In addition, a thin portion may be formed to pass the yoke 102, the rigidity of the lens frame 101 may be reduced, and the resonance characteristics may be deteriorated. 1 and 2, reference numeral 103 is an objective lens, 104 is a focus coil, 105 is a track coil, 106 is a fixing member, 107 is a suspension wire, and 108 is a magnet. In FIG. 2, when a current flows through the focus coil 104, a force in the focusing direction (Fo direction) acts on the lens frame 101, and the lens frame 101 can move in the Fo direction. Similarly, when a current is passed through the track coil 105, a force in the tracking direction (Tr direction) is applied, and the track coil 105 can move in the Tr direction.

  Further, even when the magnetic circuit is closed without making a hole in the lens frame as in the invention of Patent Document 1, the movable part becomes large, and the objective lens driving device becomes large. There's a problem.

  On the other hand, (1) as shown in the overall perspective view of FIG. 3 and the exploded perspective view of FIG. 4, or (2) as shown in the overall perspective view of FIG. 5 and the exploded perspective view of FIG. The circuit may be an open magnetic circuit. The above (1) shows an example in which the focus coil and the track coil are arranged so as to overlap each other, and the above (2) shows an example in which they are arranged side by side.

  When different coils are arranged side by side, the magnet end face is divided into a plurality of pieces as shown in FIG. 7 and FIG. 8 (examples of magnetization patterns in the case of arranging the coils as shown in FIGS. 5 and 6). As shown in FIGS. 9 and 10 (showing the direction of thrust generation when the coils are arranged in the magnets shown in FIGS. 7 and 8), the coils are arranged so as to straddle the magnetization boundary. Thrust is generated between the coils to control the position of the objective lens. If the magnetic circuit is an open magnetic circuit, it is not necessary to provide a space for passing the yoke in the movable part, so the objective lens driving device can be reduced in size, but the leakage flux is large and the efficiency of the magnetic circuit is increased. Will get worse. Therefore, in order to obtain the same thrust, it is necessary to flow a larger current, and there is a problem that energy consumption increases. In addition, there arises a problem that heat is generated by passing a large current. In FIGS. 7 and 8, the symbol Fo indicates the focusing direction, and Tr indicates the tracking direction.

JP 2001-14697 A JP-A-62-65245 JP 63-217536 A

  The present invention has been made in view of the above-described problems of the prior art. The first object of the present invention is to prevent magnetic flux leakage accurately, enable driving with a small current, and reduce the size. It is to provide an easy objective lens driving device. A second object of the present invention is to provide an optical pickup device and an optical disk drive device provided with such an objective lens driving device.

  The invention according to claim 1 includes a movable part that holds an objective lens on a lens frame, a support means (for example, a suspension wire) that movably supports the movable part, a coil and a magnet, and the movable part. In the objective lens driving apparatus, the coil is fixed to the lens frame with a magnetic material (for example, a magnetic material plate or a magnetic material piece, the same applies hereinafter) sandwiched between the magnet and the magnet. Is an objective lens driving device characterized in that is disposed in the vicinity of the coil.

  The invention according to claim 2 is the objective lens driving device according to claim 1, wherein the magnet is held in a yoke, and a magnetic path is formed by the yoke and the magnetic body.

  According to a third aspect of the present invention, there is provided a movable part having an objective lens held by a lens frame, a support means (for example, a suspension wire) for movably supporting the movable part, a coil and a magnet, and the movable part. And a driving means for electromagnetically moving the magnet, wherein the magnet is fixed to the lens frame with a magnetic material interposed therebetween, the coil is fixed to the yoke, and the magnetic path is formed by the yoke and the magnetic material. An objective lens driving device characterized in that is formed.

The invention according to claim 4 is the objective lens driving device according to any one of claims 1 to 3, wherein the magnetic body also serves as a reinforcing means for increasing the rigidity of the lens frame.
The invention according to claim 5 is the objective lens driving device according to any one of claims 1 to 4, wherein the magnetic body also serves as a center-of-gravity position adjusting means of the movable portion.
The invention according to claim 6 is characterized in that the lens frame is made of a synthetic resin and is formed integrally with a magnetic body (for example, a magnetic body plate). An objective lens driving device.
The invention according to claim 7 is the objective lens driving device according to any one of claims 1 to 3, wherein magnetic powder is applied to a coil or magnet mounting surface of the lens frame.
The invention according to claim 8 is characterized in that at least a part of the lens frame is a molded product (such as an injection molded product) made of a synthetic resin mixed with a magnetic powder. An objective lens driving device according to claim 1. As a specific example of the objective lens driving device, there is a device characterized in that the magnetic material is a magnetic material plate formed by molding a synthetic resin mixed with magnetic powder into a plate shape.

  The invention according to claim 9 is provided such that a suspension wire is provided as the support means for movably supporting the movable part, and an attractive force is generated in the direction in which the suspension wire is pulled in the wire longitudinal direction by the magnet and the magnetic body. The objective lens driving device according to claim 1, wherein the objective lens driving device is provided.

An invention according to claim 10 is an optical pickup device comprising the objective lens driving device according to any one of claims 1 to 9.
An invention according to claim 11 is an optical disk drive device comprising the objective lens drive device according to any one of claims 1 to 9.

  Invention of Claim 1: In the objective lens drive device according to the invention of Claim 1, the leakage of magnetic flux is reduced, and the magnetic flux component in the direction of acting as the driving force in the magnetic flux density is increased. It can be driven with a small current.

  Invention of Claim 2: In the objective lens driving device of Claim 1, although leakage of magnetic flux can be prevented, a closed magnetic circuit cannot be formed as a magnetic circuit. For this reason, electric power may not be converted into thrust sufficiently efficiently. On the other hand, in the invention of claim 2, since the objective lens driving device of the moving coil is used, the magnetic circuit can be closed, so that it can be converted into thrust more efficiently.

  Invention of Claim 3: Even if it is a moving magnet system, even if the same electric power is supplied if a magnetic circuit is open, a big thrust cannot be obtained. On the other hand, according to the invention of claim 3, even in the case of a moving magnet, the magnetic circuit can be made a substantially closed system without almost increasing the size of the movable part, so that efficient thrust conversion is possible. Become.

Invention of Claim 4: When the rigidity of a lens frame is insufficient and the part which attaches a coil or a magnet deform | transforms, a resonance characteristic will deteriorate and it will affect control. On the other hand, according to the invention of claim 4,
Since the portion to which the magnetic plate is attached can be made thin, it is possible to suppress the increase in the size of the movable part that accompanies the attachment of the magnetic member.

  Invention of Claim 5: If the gravity center position of a movable part and the generation position of a thrust have shifted | deviated, an unnecessary tilt will generate | occur | produce. Moreover, the attachment of the balance member only for moving the gravity center position is wasted. On the other hand, according to the invention of claim 5, the magnetic body can be provided with two functions of adjusting the center of gravity of the movable portion and forming a magnetic circuit.

  Invention of Claim 6: If a magnetic body plate is attached to a lens frame by bonding in a separate process, the operation becomes complicated. On the other hand, according to the invention of claim 6, since the magnetic plate can be attached simultaneously with the molding of the lens frame, the assembly process is reduced, and the attachment variation is reduced.

  Invention of Claim 7: If metal members, such as an iron plate, are directly mounted on a movable part, since the weight of a movable part will increase, the effect which raised the efficiency of thrust conversion will reduce. On the other hand, according to the seventh aspect of the invention, although the magnetic permeability is reduced, the magnetic path is ensured without greatly increasing the weight of the movable part, and efficient thrust conversion is possible.

  Invention of Claim 8: Since the mass of a movable part will increase if a magnetic body is all metals, even if it raises the magnetic flux density which crosses a coil and improves conversion efficiency, it may have an adverse effect. In addition, there is a possibility that work variations may occur when the magnetic material is applied. Further, in the invention of claim 7, although it is possible to suppress an increase in the weight of the movable part, the magnetic flux density may partially vary due to variations in the application work. On the other hand, according to the invention of claim 8, it is possible to suppress the variation in permeability of the magnetic path on the movable side as compared with the case where the magnetic material is applied to the surface.

  Invention of Claim 9: When a force is generated in the jitter direction, the position of the lens frame is shifted when this force acts in the direction of buckling the suspension wire as a support means for movably supporting the movable part. It can be left. On the other hand, according to the ninth aspect of the present invention, a magnet attracting force is generated in the jitter direction. However, since this attracting force acts in the direction of pulling the suspension wire, it is possible to prevent problems such as a positional deviation of the lens frame. it can.

  Inventions 10 and 11: Since the optical pickup device and the optical disk drive device according to these inventions are provided with the objective lens driving device according to any one of claims 1 to 9, the above-described effect by the driving device is obtained. can get. If the energy consumption is large in order to obtain the driving thrust of the optical pickup device, the characteristics as the optical pickup device and the characteristics as the optical disk drive device are lowered. On the other hand, according to the tenth and eleventh aspects of the present invention, since it can be driven with a small amount of power supply, the energy consumption can be reduced. Therefore, it is possible to lengthen the usage time of the power supply means in the electronic device such as a notebook computer.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First embodiment (according to claim 1)
FIG. 11 is a front sectional view showing an example of the objective lens driving device, and FIG. 12 is a front sectional view showing another example of the objective lens driving device.

  In these objective lens driving devices 10, a magnetic body is attached to the lens frame 12. That is, the objective lens driving device 10 includes an objective lens 11, a lens frame 12 that holds the objective lens 11, a suspension wire 17 that serves as a support means for movably supporting the lens frame 12, and a coil (in FIG. 11, a coil). 13, FIG. 12 includes a track coil 13A and a focus coil 13B) and a driving means that has a magnet 14 and moves the lens frame 12 electromagnetically. Further, in the objective lens driving device 10, the coil is fixed to the lens frame 12 with a magnetic body (a magnetic plate 15A, which is a magnetic plate in FIG. 11, and a magnetic piece 15B in FIG. 12) sandwiched therebetween, The magnet 14 is characterized in that it is disposed in the vicinity of the coil. The magnet 14 is fixed to the yoke 16. The objective lens 11, the lens frame 12, the coil 13, the magnetic plate 15A, etc. constitute a movable part 10A. Reference numeral 18 denotes a fixing member.

  11 and 12, the magnetic body is attached between the coil and the lens frame (objective lens frame) 12. That is, in FIG. 11, a magnetic plate 15A is provided on the coil mounting surface of the lens frame 12, and the coil 13 is mounted on the magnetic plate 15A. In FIG. 12, after attaching the magnetic piece 15 </ b> B to the groove portion around which the focus coil 13 </ b> B is wound, the focus coil 13 </ b> B is wound and the track coil 13 </ b> A is attached to the outer surface of the lens frame 12. As described above, in the objective lens driving device 10, by disposing the magnetic body in the magnetic circuit, it is possible to suppress the diffusion of the magnetic flux and increase the magnetic flux density across the coil.

  FIGS. 13A and 13B are a magnetic field analysis model and a magnetic field distribution diagram when a magnetic body is not attached to the movable part side, and FIGS. 13A and 14B are a case where a magnetic body is attached to the movable part side. It is a magnetic field analysis model of this, and a magnetic field line distribution map.

  In order to see the effect when the magnetic plate 15A is attached to the lens frame 12 (FIG. 11), the positional relationship among the yoke 16, the magnet 14, the coil 13A, and the lens frame 12 is shown in FIGS. 13 (a) and 14 (a). Thus, the magnetic field was calculated. However, FIG. 13A models the case where no magnetic material is attached between the coil and the lens frame, and FIG. 14A models the case where the magnetic material plate 15A is provided between the coil and the lens frame. . In this case, it is assumed that the magnet is magnetized in the arrow direction (jitter direction) in the figure.

The lines of magnetic force in the central cross section of the magnet 14 are distributed as shown in FIGS. 13B and 14B, respectively. It can be seen that when the magnetic body is disposed, the magnetic field lines are less likely to diverge than when the magnetic body is not disposed.
The distribution of the direction component perpendicular to the coil mounting surface of the magnetic flux density at the center position between the coil mounting surface and the magnet end surface of the lens frame 12 is shown in FIG. 15 (when no magnetic body is mounted) and FIG. When installed). When these are compared, the effect of attaching the magnetic body to the movable part side can be seen. That is, the number of lines of magnetic force that cross the coil increases, and the direction of the lines of magnetic force is closer to the direction perpendicular to the coil end face, so that the direction component of the magnetic flux density acting on the driving force is increased.

  Furthermore, as shown in FIG. 17, even when a magnet having a multipolar magnetized surface facing the coil is used, there is an effect of increasing the magnetic flux density across the coil. Examining the magnetic flux density at the center of the magnet end face and the coil attachment surface, comparing the case of FIG. 18 in which no magnetic body is attached with the case of FIG. It can be seen that (direction component perpendicular to the coil end face) increases.

  The electromagnetic force generated by the track coil, that is, the driving force F of the objective lens is determined by the following formula: F = L × I × B. Here, L is the effective coil length existing in the magnetic circuit gap among the track coils, I is the current flowing in the track coil, and B is the magnetic flux density of the magnetic circuit gap. Therefore, if the value of B increases, the same driving force can be obtained with less current.

  As described above, by attaching the magnetic body to the movable part, the weight of the movable part increases, but the magnetic flux density increases more than the increase in weight, so that the objective lens can be driven more efficiently. Further, since it is sufficient to flow a small current in order to obtain the same thrust, generation of Joule heat can be suppressed, so that thermal deformation of the lens frame and the lens can be suppressed. In addition, when a magnetic body is attached to the movable part, the direction of the magnetic flux is likely to face the magnetic body on the movable part side. can do.

  With respect to the form in which the magnetic body is disposed between the lens frame and the coil, as shown in FIGS. 11 and 12, the lens frame is not only supported by a suspension wire, but is also a shaft sliding type objective lens driving device. Is also applicable. FIG. 20 is a perspective view of such an objective lens driving device, FIG. 21 is an exploded perspective view thereof, 21 is an objective lens, 22 is a lens frame, 23 is a coil, 24 is a magnet, 26 is a yoke, and 28 is a slide. It is a dynamic axis.

  Also, as shown in FIGS. 22A and 22B, when the magnetic body 25 is disposed between the lens frame and the coil on the movable part side and supported by the suspension wire (FIGS. 11 and 12). Similarly, leakage of magnetic flux can be reduced and the magnetic flux density can be increased. 22A is a plan view of the objective lens driving device, and FIG. 22B is a cross-sectional view taken along line AA.

  Furthermore, as shown in the perspective view of FIG. 23 (a) and the exploded perspective view of FIG. 23 (b), when the printed coil substrate 31 is arranged instead of the winding coil (an objective lens driving device using the coil as the printed coil). ) Is the same, and a magnetic body can be attached to the movable part side.

Second embodiment (according to claim 2)
In the objective lens driving device according to the present embodiment, a magnetic body is disposed between a coil and a lens frame (attaching the magnetic body to the lens frame), and a magnetic circuit ( Magnetic path).

  As shown in the sectional view of FIG. 24, a magnetic plate 15A is disposed between the lens frame 12 and the coil 13. In this case, a slight gap C is formed between the magnetic plate 15 </ b> A and the fixed side yoke 16. Thus, even when the position of the lens frame 12 is moved, the magnetic circuit 14 is maintained in a substantially closed state (closed magnetic path) by the yoke 16 and the magnetic material plate 15A attached to the movable portion side.

  The major difference between the first embodiment and the second embodiment is that the magnetic plate 15A, the magnetic piece 15B and the fixed side yoke 16 are greatly separated in FIGS. On the other hand, in FIG. 24 showing the latter, the lower part of the fixed side yoke 16 is made close to the lower part of the magnetic body plate 15A (for example, by bending it to the magnetic body plate 15A side). . As a result, in the second embodiment, the magnetic flux leaking is reduced as compared with the first embodiment, and the magnetic flux density that is the basis of the objective lens driving force can be increased. That is, when the structure of FIG. 24 is modeled as shown in FIG. 25A and the magnetic field is calculated, the magnetic field line distribution is as shown in FIG. 25B.

  FIG. 14 (when a magnetic body is attached to the movable part side) and FIG. 25 (when a magnetic body is attached to the movable part side and the magnetic body and the fixed side yoke form the closed magnetic path) When FIG. 25 is compared, it turns out that the number of the magnetic force lines which cross a coil increases in FIG. 25 compared with FIG. 14, and the inclination with respect to a coil end surface is small. Further, comparing FIG. 16 with FIG. 26, even if the direction component perpendicular to the coil end surface of the magnetic flux density is compared between the magnet end surface and the coil mounting surface of the lens, the improvement effect can be obtained by the second embodiment. You can see that

  In the structure of FIG. 24, when the plate thickness of the fixed side yoke 16 is thin and a sufficient facing area cannot be obtained between the yoke 16 and the magnetic body plate 15A on the movable part side, the lower side of the yoke 16 is as shown in FIG. The facing area may be secured by providing a bent portion 16a that is a bent portion. Such a structure also improves the heat dissipation function. That is, when the coil is energized, the heat generated in the coil is transmitted through the magnetic plate 15A and escapes from the fixed side yoke 16 as well, so that a heat radiation path is secured. Therefore, heat generated in the coil is hardly transmitted to the lens frame and the lens, and there is an advantage that deformation due to a temperature rise of the lens frame and the lens can be suppressed.

Third embodiment (according to claim 3)
FIG. 28 is a front sectional view showing a moving magnet type objective lens driving device according to the present embodiment. In this method, the magnet is attached to the movable part side and the coil is attached to the fixed side, but in the case of FIG. 28, the magnetic plate 15 </ b> A is disposed between the magnet 14 and the lens frame 12. In addition, a closed magnetic path is formed by the yoke 16 to which the coil 13 is fixed and the magnetic plate 15A attached to the movable portion 41.

  FIG. 29A is a cross-sectional view showing a state in which the suspension wire is bent by the influence of the attractive force generated between the magnet and the yoke on the fixed portion side in the objective lens driving device of FIG. 28, and FIG. It is the one part enlarged view. In this embodiment, depending on the strength of the magnet 14 and the distance between the magnet 14 and the yoke 16, an attractive force F is generated between the magnet 14 and the yoke 16 on the fixed portion side as shown in FIGS. Although the suspension wire 17 may be bent at the neutral position of the lens frame 12 due to the suction force, the above-described bending can be prevented by sufficiently increasing the spring constant of the wire 17 in the focus direction. Can be prevented.

  In the objective lens driving device according to the present embodiment, as in the moving coil type objective lens driving device according to the second embodiment, the fixed side yoke 16 and the magnetic plate 15A constituting the movable portion 41 are closed. Since the path can be formed, it is possible to increase the magnetic flux density (in the portion where the driving force is generated) across the coil. Therefore, a required driving force can be generated with a small electric power, and an energy saving effect can be obtained.

Fourth embodiment (according to claim 4)
In the objective lens driving device, when the rigidity of the lens frame is low, the lens frame is easily bent and the resonance characteristics are deteriorated. Therefore, by attaching a reinforcing metal plate having rigidity higher than that of the resin to the lens frame, bending of the lens frame is suppressed, and deterioration of resonance characteristics is prevented. In this case, for example, as shown in FIG. 11, if a magnetic plate 15A is used as the reinforcing metal plate, a reinforcing (rigidity improving) effect and a magnetic flux density increasing effect affecting the driving force can be obtained simultaneously. it can. As a method for fixing the magnetic plate to the lens frame, it is preferable to use an adhesive that becomes rigid after solidification.

  Further, as shown in FIG. 30 (a), the coil attachment surface is not formed of resin, and the frame 12a for the lens frame is formed in a U-shape, and as shown in FIG. By attaching the magnetic plate 15A to the U-shaped end surface of the frame 12a to form a coil attachment surface, the lens frame 12 after the coil attachment surface is formed has five surfaces (four outer peripheral surfaces and an upper surface). May be.

Fifth embodiment (according to claim 5)
In the objective lens driving device according to the present embodiment, the position of the center of gravity of the movable portion can be set to an appropriate position by adjusting the shape of the magnetic plate and the attachment position of the magnetic plate to the lens frame. For example, by employing a structure in which the magnetic plate protrudes downward from the lens frame, the center of gravity of the movable portion can be moved downward. If the lens is made of glass, the center of gravity tends to shift upward, but if you want to move the center of gravity to the upper side, move the center of gravity of the entire movable part to the upper side by changing the lens shape. Can do. As described above, if the position and shape of the magnetic plate are adjusted, the center of gravity of the movable part can be moved to a desired position. Therefore, the magnetic plate for suppressing leakage of magnetic flux serves as a balancer. Can also be fulfilled.

Sixth embodiment (according to claim 6)
In the objective lens driving device of the present embodiment, the lens frame is manufactured as shown in FIG. 31 (a) or FIG. 31 (b). The lens frame 12 in FIGS. 31A and 31B is made of synthetic resin and is formed integrally with the magnetic plate 15A, and the magnetic plate 15A is inserted into the resin frame 12a. It is molded into As a method for producing these lens frames 12, there is a method in which a magnetic plate 15A is set in a mold and then a molten resin is injected into the mold.

  In the present embodiment, the magnetic plate 15A is attached to the frame at the time when the frame 12a is finished. In FIG. 31A, the inner surfaces of the magnetic plate 15A face each other. It exists in the state which contacted a pair of side surface (outer surface). On the other hand, in FIG. 31 (b), both ends of the resin frame 12a are formed in a U-shape, and the side surfaces of this U-shaped portion, that is, the pair of side surfaces facing each other are covered with the magnetic plate 15A. It is composed. In these frame structures, unlike the case of attaching by bonding or the like in a separate process, it is possible to suppress variations in the attachment position of the magnetic plate. Furthermore, in FIG. 31B, unlike the case of FIG. 31A, the outer surface of the frame 12a does not exist on the inner surface side of the magnetic plate 15A. However, in that the pair of side surfaces (outer surfaces) opposed to each other of the frame body 12a are formed by the magnetic body plate 15A by molding the magnetic body plate 15A into the groove 12b having a U-shaped cross section, 31A and 31B are common.

Seventh embodiment (according to claim 7)
In the objective lens driving device according to the present embodiment, a magnetic material plate is not attached to form a magnetic path, but before the coil is attached, as shown in FIG. Apply paint mixed with magnetic powder and adhesive. After that, the coil is attached.

  Further, in the case of making it correspond to the invention of claim 2 or claim 3, as shown in FIG. 33, the coil mounting surface 12c is extended and extended to the opposite side to the object lens 11 arrangement side as a frame 12a. The lens frame 12 is produced by molding a thing and applying a magnetic coating material to the mounting surface 12c. Then, a magnetic path is formed by the fixed side yoke to which the magnet is attached and the magnetic material applied as described above.

  According to this embodiment, compared with the case where a magnetic body plate is stuck on a lens frame, leakage of magnetic flux can be suppressed while minimizing the weight increase of the movable part. Moreover, if the coil, the printed coil substrate or the magnet is bonded with an adhesive mixed with magnetic powder, the magnetic powder coating process and the coil bonding process can be completed at one time. The manufacturing process can be reduced.

Eighth embodiment (according to claim 8)
When an objective lens driving device is manufactured, if a magnetic metal plate is attached to the lens frame as a magnetic material plate, the weight of the movable portion increases, so that a larger thrust is required for driving. Therefore, in order to increase the magnetic flux density across the coil and prevent an increase in the weight of the movable part, a plate material obtained by molding a mixture of resin and magnetic powder instead of a magnetic plate made of a metal plate is used as a coil and a lens. Place between frames.

  Alternatively, instead of attaching the component mixed with magnetic metal powder in a separate process, the entire lens frame may be molded with a resin mixed with magnetic powder. Thereby, an attachment work process reduces and the influence of the attachment variation of a magnetic body can be suppressed. At this time, when the ratio of the magnetic material is increased, the magnetic permeability is improved, so that the leakage magnetic flux is reduced and the magnetic flux density across the coil can be increased. However, since the ratio of the metal material increases, the weight of the lens frame increases and the strength decreases. Therefore, the mixing ratio should be appropriately set in consideration of weight, permeability, strength, and the like.

  Alternatively, the lens frame may be molded simultaneously by two-color molding, in which the coil mounting position and its periphery are made of a resin mixed with a magnetic material, and the other portions are made of a resin not mixed with a magnetic material. Compared to the case where the entire lens frame is molded from a resin mixed with magnetic powder, the weight can be reduced and the strength can be increased.

Ninth embodiment (according to claim 9)
In the objective lens driving device of the present invention, since the magnetic body is attached to the lens frame, an attractive force is generated between the magnetic body and the magnet. In the objective lens driving device according to the third aspect of the present invention, an attractive force is generated between the magnet attached to the movable portion and the yoke for holding the coil. In the configuration of these objective lens driving devices, there is no problem when the balance of the attractive forces generated by the magnets on both sides is maintained. However, if the balance is lost and the lens frame is offset or tilted by the magnet, it cannot be driven correctly. For example, in FIG. 34, when the attractive force between the magnet B and the magnetic body B becomes larger than the attractive force between the magnet A and the magnetic body A, and the suspension wire 17 buckles, the lens frame 12 and the magnet B stick to each other. (However, there is no concern with a shaft sliding type objective lens driving device.) Once this happens, it cannot be restored.

  Therefore, in order to prevent the suspension wire 17 from buckling, the magnetic force is determined so that a tensile force is applied thereto. That is, in FIG. 34, the attractive force acting between the magnet A and the magnetic body A is necessarily larger than the attractive force acting between the magnet B and the magnetic substance B. For example, by changing the magnetic force of the magnet A and the magnet B so that the attractive force of each magnet is different, or changing the distance between the magnet and the coil (the distance between the magnet and the magnetic plate on the lens frame side), the suspension wire So that a pulling force is generated. In this case, the magnetic flux density between the magnet B and the magnetic body B is smaller than that between the magnet A and the magnetic body A, so that a large current is allowed to flow, or a portion effective for driving in the coil is lengthened. If the same thrust is generated by increasing the number, the lens frame will not tilt.

Tenth and eleventh embodiments (according to claims 10 and 11)
An optical pickup device comprising: a laser light source that emits a laser beam to irradiate an optical disc; an objective lens driving device according to any one of claims 1 to 9; and a light receiving optical system that receives reflected light from the optical disc. Configure. Also, an optical disk drive device is configured by mounting this optical pickup device.

  In the optical pickup device and the optical disk drive device, the objective lens driving device can efficiently generate thrust, so that a large current is not required for driving, and heat generation from the optical pickup can be suppressed. Further, since the magnetic flux leakage from the magnetic circuit is reduced, magnetic interference with other electromagnetic components in the optical disk drive can be suppressed.

It is a perspective view which shows the conventional objective lens drive device when a magnetic circuit is a closed circuit. FIG. 2 is an exploded perspective view of FIG. 1. It is a perspective view which shows an example of the conventional objective lens drive device in case a magnetic circuit is an open circuit. FIG. 4 is an exploded perspective view of FIG. 3. It is a perspective view which shows another example of the conventional objective lens drive device in case a magnetic circuit is an open circuit. FIG. 6 is an exploded perspective view of FIG. 5. It is explanatory drawing which shows an example of the magnetization pattern at the time of arrange | positioning a coil like FIG. It is explanatory drawing which shows an example of the magnetization pattern at the time of arrange | positioning a coil like FIG. It is explanatory drawing which shows the generation direction of the thrust at the time of arrange | positioning a coil to the magnet shown in FIG. It is explanatory drawing which shows the generation direction of the thrust at the time of arrange | positioning a coil to the magnet shown in FIG. It is front sectional drawing which shows an example of the objective lens drive device which concerns on embodiment of this invention. It is front sectional drawing which shows another example of the objective lens drive device which concerns on embodiment of this invention. (A) And (b) is a magnetic field analysis model in case a magnetic body is not attached to the movable part side, and a magnetic force line distribution map. (A) And (b) is a magnetic field analysis model at the time of attaching a magnetic body to the movable part side, and a magnetic force line distribution map. FIG. 6 is a distribution diagram of directional components perpendicular to the coil mounting surface of the magnetic flux density at the center position between the coil mounting surface and the magnet end surface of the lens frame when the magnetic body is not mounted. It is a distribution diagram of the direction component perpendicular to the coil mounting surface of the magnetic flux density at the center position of the coil mounting surface and the magnet end surface of the lens frame when the magnetic body is mounted. It is explanatory drawing which shows an example of the magnet by which the surface which faces a coil was magnetized by multipolar. FIG. 18 is a distribution diagram of magnetic flux density generated by the magnet shown in FIG. 17 when a magnetic body is not attached to the movable part side. FIG. 18 is a distribution diagram of magnetic flux density generated by the magnet shown in FIG. 17 when a magnetic body is attached to the movable part side. It is a perspective view which shows an example of a shaft sliding type objective-lens drive device. It is a disassembled perspective view of FIG. An example of a shaft slide type objective lens drive device which attached a magnetic body to a lens frame is shown, (a) is a top view and (b) is the AA line sectional view. An example of the objective lens drive device which made the coil the printed coil is shown, (a) is a perspective view, (b) is an exploded perspective view. It is sectional drawing which shows an example of the objective lens drive device which formed the closed magnetic path with the magnetic body attached to the yoke of a fixed side, and a movable part. (A) is a figure which shows the magnetic field analysis model at the time of forming a closed magnetic circuit with the magnetic body and yoke which were attached to the movable part side, (b) is a magnetic force line distribution map in this case. It is a magnetic flux density distribution figure at the time of forming a closed magnetic circuit with the magnetic body and yoke which were attached to the movable part side. It is sectional drawing which shows another example of the objective lens drive device which formed the closed magnetic path with the magnetic body attached to the yoke of the fixed side and the movable part side. It is sectional drawing which shows an example of the moving-magnet-type objective lens drive device which formed the closed magnetic path with the magnetic body attached to the fixed side yoke and the movable part side. 28A is a cross-sectional view showing a state where the wire bends due to the influence of an attractive force generated between the magnet and the yoke on the fixed portion side in the objective lens driving device of FIG. 28, and FIG. FIG. This relates to an example of an objective lens driving device in which a lens frame formed into a U-shape is reinforced with a magnetic plate. (A) shows a state before the magnetic plate is attached, and (b) shows a state where the magnetic plate is attached. It is a perspective view which shows each subsequent state. (A) is a perspective view which shows an example of the lens frame produced by inserting a magnetic body in a resin-made frame, (b) is a perspective view which shows the other example. It is a perspective view which shows an example of the lens frame which apply | coated the magnetic body to the frame. It is a perspective view which shows another example of the lens frame which apply | coated the magnetic body to the frame. It is sectional drawing explaining the point for preventing buckling of a suspension wire in an objective lens drive device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Objective lens drive device 10A Movable part 11 Objective lens 12 Lens frame 12a Frame body 12b Groove 12c Coil attachment surface 13 Coil 13A Track coil 13B Focus coil 14 Magnet 15A Magnetic body plate 15B Magnetic body piece 16 Yoke (fixed side yoke)
16a bending part 17 suspension wire 18 fixing member 21 objective lens 22 lens frame 23 coil 24 magnet 25 magnetic body 26 yoke 28 sliding shaft 31 printed coil substrate 41 movable part 100 objective lens driving device 101 lens frame 102 yoke 103 objective lens 104 focus Coil 105 Track coil 106 Fixing member 107 Suspension wire 108 Magnet C Clearance F Attraction force

Claims (11)

A movable part formed by holding an objective lens on a lens frame;
Support means for movably supporting the movable part;
In an objective lens driving device comprising a driving means that electromagnetically moves the movable part having a coil and a magnet,
The coil is fixed to the lens frame with a magnetic material in between,
An objective lens driving device, wherein the magnet is arranged in the vicinity of a coil.   2. The objective lens driving device according to claim 1, wherein the magnet is held on a yoke, and a magnetic path is formed by the yoke and the magnetic body. A movable part formed by holding an objective lens on a lens frame;
Support means for movably supporting the movable part;
In an objective lens driving device comprising a driving means that electromagnetically moves the movable part having a coil and a magnet,
The magnet is fixed to the lens frame with a magnetic material in between,
Fixing the coil to the yoke;
An objective lens driving device characterized in that a magnetic path is formed by the yoke and the magnetic body.   The objective lens driving device according to claim 1, wherein the magnetic body also serves as a reinforcing unit that increases the rigidity of the lens frame.   The objective lens driving device according to claim 1, wherein the magnetic body also serves as a center-of-gravity position adjusting unit of the movable part.   The objective lens driving device according to claim 1, wherein the lens frame is made of a synthetic resin and is integrally formed with a magnetic body.   The objective lens driving device according to any one of claims 1 to 3, wherein magnetic powder is applied to a coil or magnet mounting surface of the lens frame.   4. The objective lens driving device according to claim 1, wherein at least a part of the lens frame is a molded product made of a synthetic resin mixed with a magnetic powder. A suspension wire is provided as the support means for movably supporting the movable part,
The objective lens driving device according to claim 1, wherein an attractive force is generated in a direction in which the suspension wire is pulled in the wire longitudinal direction by the magnet and the magnetic body.   An optical pickup device comprising the objective lens driving device according to claim 1. An optical disk drive device comprising the objective lens drive device according to claim 1.

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