JP2008130140A - Objective lens actuator and optical disk unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve servo performance of an objective lens actuator by regulating unnecessary generation of a resonance peak without increasing the number of components. <P>SOLUTION: The objective lens actuator comprises an objective lens for forming a spot on an optical disk, six, three pairs of, elastic supporting members 16a to 16f whose one ends are fixed to a lens supporting member at both sides of the objective lens, a substrate 201 which supports other ends of the elastic supporting members, and a substrate fixing member 202 mounted on the substrate 201 to support the objective lens in a movable fashion to the optical disk. The substrate 201 consists of a flexible section 201b of which a supporting position of the elastic supporting member is movable vertically to the substrate 201 and a fixed section 201a fixed to the substrate fixing member 202, and at least the distance from the supporting position of one pair of the elastic supporting members to the fixed section 201a on the flexible section 201b is different from the distance from the supporting position of the other pair of the elastic supporting members to the fixed position 201a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an objective lens actuator of an optical pickup and an optical disk apparatus in an optical information recording / reproducing apparatus that records or reproduces an information signal by condensing a laser beam on an information signal recording layer of the optical disk.

  An outline of a conventional optical pickup will be described.

  FIG. 6 is a diagram showing a schematic configuration of a conventional optical disc apparatus.

  Here, 1 is an optical disk, 2 is an optical pickup, and 3 is a spindle motor that rotationally drives the optical disk 1. The optical pickup 2 includes a laser light source 6, a collimator lens 7, a beam splitter 8, a condenser lens 9, a light receiving element 10, an objective lens 20, and an objective lens actuator 11 that performs focus control and tracking control on the objective lens 20. . A light spot is formed on the optical disk 1 by the objective lens 20.

  The optical disk 1 includes an information signal recording layer 13 formed on a disk substrate 12 and made of a phase change material capable of reversibly changing the phase state, and a cover layer 14 made of a transparent resin material. A spiral or concentric recording track is formed on the information signal recording layer 13. The information signal recording layer 13 may be made of a magneto-optical recording material or a metal reflection film having pits (unevenness). The optical pickup 2 is disposed on the side of the optical disc 1 that faces the cover layer 14.

  In recent years, an objective lens actuator mounted on an optical pickup needs to cope with disc warping in order to improve signal recording / reproduction quality. Therefore, a tilt actuator is mounted that tilts the optical axis of the objective lens and tilts the objective lens in the radial direction of the disk so that the laser beam is incident perpendicularly to the disk.

  In such an objective lens actuator, the objective lens 20 is supported on the fixed portion by six (three pairs) elastic support members, and Patent Document 1 below discloses this example. On the other hand, Patent Document 2 below discloses an example in which an elastic support member is supported on a fixed portion via a flexible substrate. Thereby, the objective lens actuator provided with the six elastic support members shown below can be implemented.

  FIG. 7 is a diagram showing a configuration of an objective lens actuator provided with six conventional elastic support members.

  In FIG. 7, the focus direction, the tracking direction, the tangential direction, and the radial tilt direction are shown as the Fo direction, the Tr direction, the Tan direction, and the Rad tilt direction, respectively.

  The objective lens actuator 11 includes a support portion 26 and a movable portion 25. The support portion 26 includes permanent magnets 21 a, 21 b, 21 c, a yoke 24, a substrate 101, a substrate fixing member 102, and a support base 17. The movable portion 25 includes an objective lens 20, focus coils 19a and 19b, a tracking coil 18, and a lens holding member 15 that holds these. The six elastic support members 16a, 16b, 16c, 16d, 16e, and 16f are linear and have elasticity and high conductivity, and one end is a lens holding member in the focusing direction (optical axis direction) on both sides of the objective lens 20. 15, the other end is fixed to the substrate 101 of the support portion 26.

  FIG. 8A is a perspective view showing a configuration of a substrate and a substrate fixing member provided in an objective lens actuator in a conventional example, FIG. 8B is a top view thereof, and FIG. 8C is a rear view thereof.

  The six elastic support members 16a-16f are electrically connected at six support positions (W1a, W1b, W2a, W2b, W3a, W3b) of the substrate 101 as shown in FIGS. 8a, 8b, and 8c. The substrate 101 is fixed to the substrate fixing member 102. The substrate 101 vertically supports the other ends of the elastic support members 16 a to 16 f, and a support portion 101 a that is fixed to the substrate fixing member 102 and a flexible portion 101 b that can be displaced in a direction perpendicular to the substrate 101. Consists of. The flexible part 101b can be displaced by elastic deformation. Normally, when the objective lens actuator 11 is driven in the focus direction and the tracking direction, an abnormal amplitude occurs at the center of the objective lens 20 of the lens holding member 15 due to unnecessary resonance. In order to suppress this phenomenon, the support position of the elastic support members 16a-16f on the support portion 26 side can be displaced in a direction perpendicular to the substrate 101, and the flexible portion 101b is displaced to suppress unnecessary resonance. It has become. The distances from the fixed portion 101a of the six pairs of three support positions W1a (W1b), W2a (W2b), and W3a (W3b) are Oa (Ob) in the figure and are constant.

  One end of each of the elastic support members 16a to 16f holds the movable portion 25 so that the movable portion 25 can be displaced in the focus direction, the tracking direction, and the radial tilt direction with respect to the optical disc 1. Here, the winding terminals of the focus coils 19a and 19b and the tracking coil 18 and the elastic support members 16a to 16f are electrically connected.

  Furthermore, as shown in FIG. 6, the optical pickup device includes an error signal generation circuit 4 and a control circuit 5 for performing focus control, tracking control, and tilt control of the objective lens actuator 11. The control circuit 5 supplies a control current to the focus coils 19a and 19b and the tracking coil 18 through the elastic support members 16a to 16f.

  The control circuit 5 supplies a control current based on the focus error signal and the tracking error signal to the focus coils 19a and 19b and the tracking coil 18 through the elastic support members 16a to 16f. The actuator 11 generates a driving force in three directions on the movable portion 25 by an electromagnetic force generated between the control current and the magnetic flux generated by the permanent magnets 21a, 21b, and 21c. These are a focus direction of the objective lens 20 with respect to the optical disc 1, a tracking direction orthogonal to the recording track, and a radial tilt direction about the tangential direction (tangential direction) of the recording track. For example, the radial tilt driving method of the objective lens actuator 11 shown in FIG. 7 is driven by generating thrusts opposite to each other due to a voltage difference applied to the focus coils 19a and 19b. Regarding the tilt drive, although not shown here, other configurations are possible depending on the coil arrangement of the movable portion 25.

Thus, even if the optical disc 1 is displaced in the focus direction due to the surface shake, the light spot is controlled to be accurately focused on the recording track following this. Further, even if the recording track is displaced in the tracking direction due to eccentricity, tracking control is performed so that scanning is performed following the recording track, and tilt control is performed in order to correct the influence of disc tilt or the like.
JP 2003-223732 A JP-A-10-124895

  However, the objective lens actuator provided with the six elastic support members of the conventional optical pickup has the following problems. That is, the objective lens actuator provided with six elastic support members has a problem that the peak of the sub-resonance is easily separated compared to the objective lens actuator provided with four elastic support members.

  FIG. 9 is a graph showing frequency characteristics at the time of tracking drive of an objective lens actuator including six elastic support members.

  A plurality of peaks of yawing (oscillation in the track direction of the objective lens 20 around the base end of the elastic support member 16), which is sub-resonance, occur in the circled portion. This is because the number of elastic support members 16 is six and the support positions on the substrate 101 are six, and therefore the influence of the occurrence of multiple resonances of the elastic support member 16 and the substrate 101 is dominant. Thus, in an objective lens actuator having six elastic support members, the occurrence of an unnecessary resonance peak in the frequency characteristic is a problem because the servo characteristic becomes unstable.

  Therefore, the present invention has been proposed to solve such a conventional problem, and without increasing the number of parts, the generation of unnecessary resonance peaks is suppressed and the servo characteristics of the objective lens actuator are improved. For the purpose.

In order to solve the above problems, an objective lens actuator according to the present invention includes an objective lens that forms a light spot on an optical disc, and three pairs of elastic support members each having one end fixed to a lens holding member on both sides of the objective lens. And an objective lens actuator that includes a substrate that supports the other end of the elastic support member, a substrate fixing member that is attached to the substrate, and that supports the objective lens to be displaceable with respect to the optical disc
The substrate includes a flexible portion in which a support position of the elastic support member can be displaced in a direction perpendicular to the substrate, and a fixing portion fixed to the substrate fixing member.
The distance from the support position of at least one pair of elastic support members in the flexible part to the fixed part is different from the distance from the support position of another pair of elastic support members to the fixed part.

  Furthermore, the present invention provides the following optical disc apparatus.

A light source and an objective lens actuator,
The objective lens actuator includes an objective lens that forms a light spot from the light source on an optical disc, six pairs of three elastic support members having one end fixed to a lens holding member on both sides of the objective lens, and the elastic support member. In an optical disc apparatus comprising a substrate that supports the other end of the substrate and a substrate fixing member attached to the substrate,
The substrate includes a flexible portion in which a support position of the elastic support member can be displaced in a direction perpendicular to the substrate, and a fixing portion fixed to the substrate fixing member.
The distance from the support position of at least one pair of elastic support members in the flexible part to the fixed part is different from the distance from the support position of another pair of elastic support members to the fixed part.

  According to the present invention, in the objective lens actuator provided with six elastic support members, an unnecessary resonance peak is suppressed by adopting a structure that improves the vibration damping action of only one pair of the center two of the six pairs. Servo characteristics can be improved.

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

[Embodiment 1]
Embodiment 1 of the present invention will be described with reference to FIGS. 1a, 1b, 1c, 2, and 3. FIG.

  The schematic configuration of the optical pickup of the present invention is the same as the conventional one shown in FIG.

  FIG. 1a is a perspective view showing a configuration of a substrate and a substrate fixing member provided in the objective lens actuator of Embodiment 1 of the present invention, FIG. 1b is a top view thereof, and FIG. 1c is a rear view thereof.

  FIG. 2 is a diagram illustrating a configuration of an objective lens actuator including six elastic support members.

  The reference numerals of the constituent elements other than the objective lens actuator, the substrate, and the substrate fixing member shown in FIGS. 1a, 1b, 1c, and 2 are the same as those in the prior art shown in FIGS. . Since the schematic configuration of the objective lens actuator 111 is the same as that of the prior art, detailed description thereof is omitted.

  In FIG. 2, an objective lens 20 that forms a light spot from a light source on an optical disk is held by a lens holding member 15. One end of each pair of elastic support members 16 a to 16 f arranged in the focus direction of the objective lens 20 is fixed on both sides of the lens holding member 15.

  The six pairs of elastic support members 16a-16f are electrically connected at six support positions (W1a, W1b, W2a, W2b, W3a, W3b) of the substrate 201 as shown in FIGS. 1a, 1b, and 1c. The substrate 201 is connected and fixed to the substrate fixing member 202. The substrate 201 includes a flexible portion 201 b that vertically supports the other end of the elastic support member and whose support position can be displaced in a direction perpendicular to the substrate 201, and a fixing portion 201 a that is fixed to the substrate fixing member 202. The flexible part 201b can be displaced by elastic deformation. In the present invention, the distances from the six pairs of three support positions W1a (W1b), W2a (W2b), and W3a (W3b) to the fixed portion 201a are not constant. The distance from the support position of at least one pair of elastic support members to the fixing portion 201a is different from the distance from the support position of another pair of elastic support members to the fixing portion 201a. In the present embodiment, the substrate fixing member 202 is formed with recesses on both sides of the center so as to widen the flexible portion 201b of the substrate 201. For this reason, even if the three pairs of elastic support members have the same width and are aligned in the vertical direction (focus direction), the distance from the support positions W1a, W3a to the fixed portion 201a on one side is determined from Pa, W2a to the fixed portion. The relationship Pa <Qa is established, where Qa is the distance to 201a. Similarly, on the other side, Pb <Qb is established, where Pb is the distance from the support positions W1b and W3b to the fixed portion 201a, and Qb is the distance from W2b to the fixed portion 201a.

  With this structure, the elastic support member supported by W2a and W2b has a longer distance to the fixing portion 201a of the substrate 201 than the elastic support member supported by W1a, W1b, W3a, and W3b. Usually, with respect to the position of the elastic support member in the flexible portion of the substrate, the vibration damping action increases as the distance from the fixed portion increases, and the secondary resonance peak tends to be suppressed. This is because the deflection of the support position of the elastic support member increases as the distance from the support position of the elastic support member to the fixed portion in the flexible portion increases. That is, since the deflection of the support position of the elastic support member when the same force is applied due to the decrease in elasticity of the flexible portion and the repulsive force against the elastic support member is reduced, unnecessary influence on the vibration characteristics of the movable portion is reduced. Decreases. Therefore, an unnecessary peak with respect to the vibration characteristic of the movable part is attenuated and becomes close to an ideal frequency response curve. For this reason, if it is set as the structure of this invention, it will become possible to reduce a subresonance peak by the elastic support member supported by W2a and W2b.

  FIG. 3 is a graph showing frequency characteristics during tracking driving of the objective lens actuator.

  As shown in FIG. 3, there is only one yawing peak that is a sub-resonance, and it is possible to make the characteristics equivalent to those of an objective lens actuator including four elastic support members in a pseudo manner. For this reason, in the objective lens actuator, unnecessary resonance peaks can be suppressed, and tilt driving can be performed by providing six elastic support members.

[Embodiment 2]
A second embodiment of the present invention will be described with reference to FIGS. 4a, 4b, 4c, and 5. FIG.

  Since the schematic configuration of the optical pickup of the present invention is the same as that of the conventional one shown in FIG. 6 and the first embodiment, detailed description thereof is omitted.

  4A is a perspective view showing a configuration of a substrate and a substrate fixing member provided in the objective lens actuator of Embodiment 2 of the present invention, FIG. 4B is a top view thereof, and FIG. 4C is a rear view thereof.

  FIG. 5 is a diagram illustrating a configuration of the objective lens actuator.

  4A, FIG. 4B, FIG. 4C, and FIG. 5 have the same reference numerals as those of the conventional elements shown in FIG. 7 and FIG. 8 except for the objective lens actuator, the substrate, and the substrate fixing member. . Since the schematic configuration of the objective lens actuator 211 is the same as that of the prior art, detailed description thereof is omitted.

  In FIG. 5, the objective lens 20 that forms a light spot on the optical disk is held by a lens holding member 15. One end of each pair of elastic support members 16 a to 16 f arranged in the focus direction of the objective lens 20 is fixed on both sides of the lens holding member 15.

  As shown in FIGS. 4a, 4b, and 4c, the six pairs of elastic support members 16a to 16f are electrically provided at six support positions (W1a, W1b, W2a, W2b, W3a, and W3b) of the substrate 301. The substrate 301 is connected and fixed to the substrate fixing member 302. The substrate 301 includes a flexible portion 301 b that vertically supports the other end of the elastic support member, the support position of which can be displaced in the vertical direction of the substrate 301, and a fixing portion 301 a that is fixed to the substrate fixing member 302. The flexible part 301b can be displaced by elastic deformation. In the present invention, the width in the horizontal direction of the flexible portion 301b is constant, but the distance from the three pairs of support positions W1a (W1b), W2a (W2b), and W3a (W3b) to the fixed portion 301a is constant. Absent. The distance from the support position of at least one pair of elastic support members to the fixed portion 301a is different from the distance from the support position of another pair of elastic support members to the fixed portion 301a. In this embodiment, the three pairs of elastic support members are not aligned in the vertical direction (focus direction), and are attached so that the width of the central pair of elastic support members is larger than the width of the other pair of elastic support members. It has been. Therefore, on one side, the relationship Pa <Qa is established, where Pa is the distance from the support positions W1a, W3a to the fixed portion 301a, and Qa is the distance from the W2a to the fixed portion 301a. Similarly, on the other side, the relationship Pb <Qb is established, where Pb is the distance from the support positions W1b and W3b to the fixed portion 301a, and Qb is the distance from the W2b to the fixed portion 301a.

  With this structure, the elastic support member supported by W2a (W2b) has a greater damping effect and can reduce the resonance peak than the elastic support member supported by W1a (W1b) and W3a (W3b). It becomes. Similar to the frequency characteristics seen in the first embodiment, there is only one yawing peak that is a secondary resonance, and it can be made to be equivalent to the characteristics of an objective lens actuator having four elastic support members in a pseudo manner. Become. For this reason, in the objective lens actuator, unnecessary resonance peaks can be suppressed, and tilt driving can be performed by providing six elastic support members.

The perspective view which shows the structure of the board | substrate with which the objective lens actuator of Embodiment 1 of this invention was equipped, and the board | substrate fixing member. Top view Rear view The figure which shows the structure of the objective lens actuator provided with the six elastic support members of the Embodiment 1. The graph which shows the frequency characteristic at the time of the tracking drive of the objective lens actuator of Embodiment 1 The perspective view which shows the structure of the board | substrate with which the objective lens actuator of Embodiment 2 of this invention was equipped, and the board | substrate fixing member. Top view Rear view The figure which shows the structure of the objective-lens actuator provided with the six elastic support members of the Embodiment 2. The figure which shows schematic structure of the optical pick-up of a prior art example The figure which shows the structure of the conventional objective lens actuator provided with six elastic support members. The perspective view which shows the structure of the board | substrate with which the objective lens actuator in the prior art example was equipped, and a board | substrate fixing member. Top view Rear view The graph which shows the frequency characteristic at the time of the tracking drive of the objective lens actuator provided with six elastic support members

Explanation of symbols

DESCRIPTION OF SYMBOLS 11, 111, 211 ... Objective lens actuator 15 ... Lens holding member 16a, 16b, 16c, 16d, 16e, 16f ... Elastic support member 17 ... Support base 20 ... Objective lens 25 ... Movable part 26 ... Support part 101, 201, 301 ... Substrate 102, 202, 302 ... Substrate fixing member

Claims (8)

An objective lens for forming a light spot on an optical disc, six pairs of elastic support members having one end fixed to a lens holding member on both sides of the objective lens, a substrate for supporting the other end of the elastic support member, In an objective lens actuator that includes a substrate fixing member attached to a substrate and supports the objective lens so as to be displaceable with respect to the optical disc.
The substrate includes a flexible portion in which a support position of the elastic support member can be displaced in a direction perpendicular to the substrate, and a fixing portion fixed to the substrate fixing member.
An objective lens actuator characterized in that the distance from the support position of at least one pair of elastic support members to the fixed part in the flexible part is different from the distance from the support position of another pair of elastic support members to the fixed part. .   Each pair of the elastic support members is arranged in the focus direction of the objective lens, and the distance from the support position of the central pair of elastic support members to the fixed portion in the flexible portion of the substrate is the other pair of elastic supports. The objective lens actuator according to claim 1, wherein the objective lens actuator is longer than a distance from a supporting position of the member to the fixed portion.   The objective lens actuator according to claim 2, wherein the substrate fixing member is formed with a concave portion on both sides of the center to widen the flexible portion of the substrate.   The objective lens actuator according to claim 2, wherein the elastic support member has a center pair having a width greater than that of the other pair. A light source and an objective lens actuator,
The objective lens actuator includes an objective lens that forms a light spot from the light source on an optical disc, six pairs of three elastic support members having one end fixed to a lens holding member on both sides of the objective lens, and the elastic support member. In an optical disc apparatus comprising a substrate that supports the other end of the substrate and a substrate fixing member attached to the substrate,
The substrate includes a flexible portion in which a support position of the elastic support member can be displaced in a direction perpendicular to the substrate, and a fixing portion fixed to the substrate fixing member.
An optical disk apparatus, wherein a distance from a support position of at least one pair of elastic support members to the fixed part in the flexible part is different from a distance from support positions of another pair of elastic support members to the fixed part.   Each pair of the elastic support members is arranged in the focus direction of the objective lens, and the distance from the support position of the central pair of elastic support members to the fixed portion in the flexible portion of the substrate is the other pair of elastic supports. 6. The optical disk device according to claim 5, wherein the distance is longer than a distance from a supporting position of the member to the fixed portion.   The optical disk apparatus according to claim 6, wherein the substrate fixing member is formed with a recess on both sides of the center to widen the flexible portion of the substrate.   7. The optical disc apparatus according to claim 6, wherein the elastic support member has a central pair having a width greater than that of the other pair.

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