JP4543266B2 - Objective lens actuator and optical pickup including the same - Google Patents

Description

  The present invention relates to an objective lens actuator used for an optical pickup, and more particularly to a structure of an objective lens actuator that supports a lens holder that holds an objective lens with a rod-like elastic support member and swings the objective lens together with the lens holder. The present invention also relates to an optical pickup provided with such an objective lens actuator.

  Optical disks such as compact disks (hereinafter referred to as CDs) and digital versatile disks (hereinafter referred to as DVDs) are in widespread use. Furthermore, recently, optical discs capable of recording large-capacity information such as Blu-ray discs (hereinafter referred to as BD) and HD-DVDs have been put into practical use. An optical pickup is used for reading information recorded on such an optical disc and writing information on the optical disc.

  In the optical pickup, it is necessary to perform control (focusing control) so that the light emitted from the light source is always focused on the recording surface of the optical disk regardless of the surface shake of the optical disk or the like when reading or writing information. Further, it is necessary to perform control (tracking control) so that the light spot emitted from the light source and formed on the recording surface of the optical disc follows the track formed on the optical disc.

  Conventionally, an optical pickup is provided with an objective lens actuator so as to perform such focusing control and tracking control. Conventionally proposed objective lens actuators include a lens holder that holds an objective lens supported by a rod-like elastic support member, and the objective lens can be swung together with the lens holder to perform focusing control and tracking control ( For example, see Patent Documents 1 and 2.)

  In this type of objective lens actuator, it is known that resonance such as pitching resonance and yawing resonance occurs in a relatively high frequency band (for example, between 1 kHz and 5 kHz). Such resonance may adversely affect the transfer characteristics of the objective lens actuator and may make servo control such as focus control and tracking control difficult.

For this reason, conventionally, as shown in Patent Documents 1 and 2, for example, unnecessary resonance such as pitching resonance or yawing resonance is provided by providing a slit (notch groove) on a rigid printed board to which one end of a rod-like elastic support member is fixed. Has been done to reduce.
JP-A-4-319537 JP-A-5-266507

  However, the following problem may occur in the configuration in which a slit is provided in a rigid printed board to reduce unnecessary resonance. FIG. 9 is an explanatory diagram for explaining a problem that occurs in the configuration in which the slit is provided in the rigid printed board. FIG. 9A is a diagram in the case where the slit is not provided in the rigid printed board, and FIG. ) Is a view when a slit is provided in a rigid printed circuit board. The rigid printed circuit board 101 in FIG. 9 is electrically connected to the control unit by the flexible printed circuit board 102 so as to receive a signal from the control unit that controls the entire optical pickup. A printed circuit board 102 is also shown.

  As shown in FIG. 9, when the slit 103 is provided in the rigid printed circuit board 101, an extra space is required in the rigid printed circuit board 101 in order to form the slit 103. Therefore, the distance between the upper rod-like elastic support member 104a and the lower rod-like elastic support member 104a is widened, and the height of the objective lens actuator is increased (FIG. 9 shows a state where it is increased by ΔL). This is a problem considering the demand for smaller objective lens actuators. Although it is conceivable to reduce the width of the slit to satisfy the demand for miniaturization, in this case, it becomes difficult to manufacture the rigid printed circuit board 101, which causes problems such as an increase in cost.

  In view of the above points, an object of the present invention is to provide an objective lens actuator that can reduce unnecessary resonance without increasing the size of the apparatus. Another object of the present invention is to provide an optical pickup capable of stably reading and writing information and reducing the size of the apparatus by providing such an objective lens actuator.

  In order to achieve the above object, the present invention includes a plurality of bases, a lens holder that holds an objective lens, and a plurality of and the same number of first and second sides that sandwich the lens holder. A rod-like elastic support member having one end fixed to the lens holder and supporting the lens holder so as to be swingable with respect to the base, wherein the objective lens actuator is stationary with respect to the base. A rigid printed circuit board having a notch, and a flexible printed circuit board fixed to the rigid printed circuit board, wherein each of the first side and the second side includes a plurality of the rod-like elastic members. Among the support members, a part of the other end is fixed to the rigid printed circuit board, and the other part except the part is the other end of the flexible printed circuit board. The flexible printed circuit board is not disposed at a portion where the other end portion of the rod-shaped elastic support member is fixed to the rigid printed circuit board, and the other end of the rod-shaped elastic support member of the flexible printed circuit board is not disposed. The portion to which the end is fixed is arranged on the notch.

  According to this configuration, a plurality of rod-like elastic support members are mixed with a position where one end is fixed as a rigid printed board and a position as a flexible printed board fixed to the rigid printed board. It is the composition to do. And the flexible printed circuit board is not arranged in the portion where the rod-like elastic support member of the rigid printed circuit board is fixed, and the portion where the rod-shaped elastic support member of the flexible printed circuit board is fixed is on the notch portion of the rigid printed circuit board. It becomes the composition arranged. For this reason, it is possible to reduce unnecessary resonance as in the conventional configuration in which the rigid printed circuit board is provided with the slit. Furthermore, the problem of increasing the size of the apparatus when a slit is provided can be solved.

  In the objective lens actuator configured as described above, a reinforcing plate may be attached to a part of the flexible printed board. According to this configuration, since the strength of a part of the flexible printed circuit board can be increased, the soldering operation is easy. It is also possible to strengthen the fixation of the rod-like elastic support member.

  In the objective lens actuator configured as described above, it is preferable that the rigid printed circuit board is disposed closer to the front side than the flexible printed circuit board when viewed from the lens holder side. The rigid printed circuit board is thicker than the flexible printed circuit board. For this reason, if the rigid printed circuit board is arranged on the outer surface side (the back side as viewed from the lens holder side) than the flexible printed circuit board, it becomes difficult to perform operations such as soldering. In this regard, in the configuration in which the flexible printed circuit board is on the outer surface side of the rigid printed circuit board, the flexible printed circuit board is thinner than the rigid printed circuit board, so that it is easy to perform operations such as soldering.

  Further, according to the present invention, in the objective lens actuator configured as described above, three rod-shaped elastic support members are disposed on each of the first side and the second side, and the two outer rod-shaped members are disposed. The elastic support member may have the other end fixed to the rigid printed circuit board, and the middle elastic support member may have the other end fixed to the flexible printed circuit board.

  In order to achieve the above object, the optical pickup of the present invention is characterized by including the objective lens actuator having the above structure. According to this, since the objective lens actuator can reduce unnecessary resonance without increasing the size of the device itself, an optical pickup capable of stably reading and writing information and reducing the size of the device is provided. it can.

  According to the present invention, it is possible to provide an objective lens actuator that can reduce unnecessary resonance without increasing the size of the apparatus. Further, according to the present invention, by providing such an objective lens actuator, it is possible to provide an optical pickup capable of stably reading and writing information and reducing the size of the apparatus.

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

(Schematic configuration of optical pickup)
First, a schematic configuration of the optical pickup of the present embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram showing a configuration of an optical system provided in the optical pickup of the present embodiment. The optical pickup 1 of the present embodiment is provided so as to be able to read information and write information to a BD, DVD, and CD.

  As shown in FIG. 1, the optical pickup 1 includes two types of optical systems. One of them is an optical system for BD, and the other is an optical system for DVD and CD (DVD / CD). These two types of optical systems are switched and used depending on the type of optical disc 50 (in this case, BD, DVD, or CD) on which information is read or written by the optical pickup 1. Hereinafter, the optical system for BD and the optical system for DVD / CD will be described separately.

  The BD optical system includes a first laser diode 11, a diffractive element 12, a polarizing beam splitter 13, a first collimating lens 14, a quarter-wave plate 15, a first raising mirror 16, a first An objective lens 17, a first cylindrical lens 18, and a first photo detector 19 are provided.

  The first laser diode 11 is a light source that emits laser light having a wavelength of 405 nm. The laser light emitted from the first laser diode 11 is divided into a main beam and two sub beams by the diffraction element 12. Laser light emitted from the diffraction element 12 is reflected by the polarization beam splitter 13 and sent to the first collimating lens 14.

  The first collimating lens 14 can be moved in the optical axis direction (the direction of the arrow shown in FIG. 1) by a driving means (not shown), and the convergent and divergent state of the laser light incident on the first objective lens 17 is changed depending on the position. To change. The reason for this configuration is to enable correction of spherical aberration.

  The laser light emitted from the first collimating lens 14 passes through a quarter-wave plate 15 that functions as an optical isolator in cooperation with the polarizing beam splitter 13, is reflected by the first rising mirror 16, and is reflected by the first objective lens. 17 is incident. The first objective lens 17 focuses the incident laser light on the recording surface 50 a of the optical disc 50.

  The laser beam reflected by the optical disk 50 is transmitted through the first objective lens 17, reflected by the first rising mirror 16, transmitted in the order of the quarter-wave plate 15 and the first collimating lens 14, and further, a polarization beam splitter. 13 is also transmitted. The laser beam that has passed through the polarizing beam splitter 13 passes through the first cylindrical lens 18 having a function of providing astigmatism, and is focused on the light receiving surface of the first photodetector 19. The first photodetector 19 converts the incident optical signal into an electrical signal and outputs it. The electrical signal output here is processed by a signal processing unit (not shown) to become a reproduction signal, a focus error signal, a tracking error signal, or the like.

  Next, an optical system for DVD / CD will be described. The optical system for DVD / CD includes a second laser diode 21, a half mirror 22, a second collimating lens 23, a second raising mirror 24, a second objective lens 25, a second cylindrical lens 26, A second photo detector 27.

  The second laser diode 21 is a two-wavelength laser that can emit by switching between a laser beam having a wavelength of 650 nm and a laser beam having a wavelength of 780 nm. The laser light emitted from the second laser diode 21 is reflected by the half mirror 22, sent to the second collimating lens 23, and converted into parallel light.

  Laser light (parallel light) emitted from the second collimating lens 23 is reflected by the second raising mirror 24, enters the second objective lens 25, and is condensed on the recording surface 50 a of the optical disc 50.

  The laser light reflected by the optical disk 50 is transmitted through the second objective lens 25, then reflected by the second raising mirror 24, and transmitted through the second collimating lens 23 and the half mirror 22 in this order, thereby providing astigmatism. And is condensed on the light receiving surface of the second photodetector 27. The second photodetector 27 converts the incident optical signal into an electrical signal and outputs it. The electrical signal output here is processed by a signal processing unit (not shown) to become a reproduction signal, a focus error signal, a tracking error signal, or the like.

  The configuration of the optical system of the optical pickup 1 shown here is merely an example, and various modifications can be naturally made without departing from the object of the present invention. In the optical pickup 1 of the present embodiment, the BD optical system and the DVD / CD optical system are completely independent. However, differently, for example, a part of the optical members may be configured to be used in common when reproducing BD, DVD, and CD information. Of course, various optical members such as an aberration correction element for correcting the wavefront aberration may be added as necessary.

  The details of the first objective lens 17 and the second objective lens 25 are movable in a focus direction and a tracking direction by an objective lens actuator 30 described later in detail. Thereby, focusing control and tracking control in the optical pickup 1 are possible.

  The focus direction is the direction in which the objective lenses 17 and 25 are in contact with and away from the optical disk 50 (the vertical direction in FIG. 1), and the tracking direction is the direction parallel to the radial direction (radial direction) of the optical disk 50. (In FIG. 1, the direction perpendicular to the paper surface).

(Configuration of objective lens actuator)
Next, details of the configuration of the objective lens actuator 30 provided in the optical pickup 1 of the present embodiment will be described with reference to FIGS. 2, 3, and 4. Here, FIG. 2 is a schematic perspective view showing the configuration of the objective lens actuator of the present embodiment. FIG. 3 is a schematic plan view showing a configuration of a portion including a rigid printed board and a flexible printed board included in the objective lens actuator of the present embodiment. FIG. 4 is a schematic plan view showing each part by disassembling the configuration shown in FIG. 3, FIG. 4 (a) is a schematic plan view of a rigid printed board, and FIG. 4 (b) is a schematic plan view of a flexible printed board. is there.

  Referring to FIG. 2, the objective lens actuator 30 of the present embodiment includes a base 31, a lens holder 32, a pair of permanent magnets 33, a gel holder 34, a rigid printed circuit board 35, a flexible printed circuit board 36, and 6. Wire (rod-like elastic support member) 37.

  The base 31 is made of a metal having ferromagnetism. The base 31 is formed with a through hole (not shown) through which the laser beam passes substantially at the center. The lens holder 32 is arranged on the through hole. A pair of permanent magnets 33 and a gel holder 34 are fixedly disposed on the base 31.

  The lens holder 32 is formed of a liquid crystal polymer (LCP) or the like and holds the objective lenses 17 and 25. In the present embodiment, since the optical pickup 1 has two objective lenses 17 and 25, the lens holder 32 has two holders (see FIG. 2) so that the two objective lenses 17 and 25 can be held. Not shown). The two holding portions are respectively connected to optical path holes (not shown) through which laser light passes, whereby the laser light from the first laser diode 11 passes through the first objective lens 17 and the laser from the second laser diode 21. The light passes through the second objective lens 25.

  A focus coil (not shown) wound in a substantially rectangular shape is attached to the inside of the lens holder 32 along the inner wall with an adhesive or the like. In addition, on each of the two side walls facing the permanent magnet 33 among the side walls of the lens holder 32, the tracking coils 38 are attached with an adhesive or the like so as to be arranged in pairs on the left and right. The tracking coils 38 formed on the two opposing side walls are arranged symmetrically. The four tracking coils 38 are connected by a single line as a whole.

  The pair of permanent magnets 33 erected on the base 31 are made of, for example, rare earth magnets, and are arranged to face each other with a predetermined interval so as to sandwich the lens holder 32. The pair of permanent magnets 33 are arranged so that the same pole (N pole or S pole) faces each other. Each of the pair of permanent magnets 33 is magnetically attached to a yoke 31 a whose outer surface is bent from the base 31.

  The gel holder 34 made of a resin molded product such as polycarbonate is disposed on the outer surface side of the yoke 31a magnetically attached to one of the pair of permanent magnets 33 (the side opposite to the side where the permanent magnets 33 are present). The gel holder 34 is formed with a pair of insertion holes 34a symmetrically. Each of the pair of insertion holes 34a is filled with a gel material mainly composed of silicon. The gel material is obtained by injecting a low-viscosity gel material (sol) into each insertion hole 34a of the gel holder 34 and then curing the gel material by ultraviolet irradiation for a predetermined time.

  The rigid printed circuit board 35 and the flexible printed circuit board 36 are circuit boards for receiving a signal from a control unit that controls the entire optical pickup 1 and transmitting the signal to the objective lens actuator 30. The rigid printed circuit board 35 is fixedly arranged on the outer surface side of the gel holder 34. The flexible printed circuit board 36 is fixedly disposed on the outer surface side of the rigid printed circuit board 35.

  The rigid printed circuit board 35 is fixed to the gel holder 34 and the flexible printed circuit board 36 is fixed to the rigid printed circuit board 36 using, for example, a thermosetting adhesive. However, screws or the like may be used instead of the adhesive. Further, as described later, the rigid printed board 35 and the flexible printed board 36 may be fixed only by soldering in order to solder between terminal portions (lands) formed on each of them.

  Referring to FIG. 4A, the rigid printed circuit board 35 is formed in a substantially rectangular shape, and a substantially rectangular cutout portion 351 is formed in the center on each of the left and right end portions. Further, a through hole 352 and a first land 353 are formed on each of the upper side and the lower side on the left and right end sides. A wiring 354 extends from each first land 353 and is connected to the second land 355.

  Referring to FIG. 4B, the flexible printed circuit board 36 includes a first portion 361 having a substantially rectangular shape, and a second portion 362 extending from the vicinity of the center of the first portion 361 to the left and right in the shape of an arm. The third portion 363 extends from the first portion 361 to the lower side and is finally connected to a control unit that controls the entire optical pickup 1. A through hole 364 and a third land 365 are formed on the end portion side of the second portion 362, respectively. In addition, fourth lands 366 are formed at the four corners of the first portion 361, respectively. In FIG. 4B, the wiring formed on the flexible printed circuit board 36 is omitted (the same applies to other drawings).

  Referring to FIG. 3, in flexible printed circuit board 36 fixed to rigid printed circuit board 35, a part of second part 362 (a part including a part provided with through hole 364) is a notch part of rigid printed circuit board 35. 351. The width of the notch 351 (vertical length in FIG. 3) is slightly larger than the width of the second portion 362 (vertical length in FIG. 3). Accordingly, a part of the second portion 362 of the flexible printed circuit board 36 can be bent in the paper surface direction of FIG. 3 without contacting the rigid printed circuit board 35.

  Further, the flexible printed circuit board 36 is arranged so that the fourth land 366 is adjacent to the second land 355 formed on the rigid printed circuit board 35. Then, the second land 355 and the fourth land 366 are soldered, and the rigid printed board 35 and the flexible printed board 36 are electrically connected. Note that the flexible printed circuit board 36 is not disposed on the rigid printed circuit board 35 in the vicinity of the through hole 352 of the rigid printed circuit board 35.

  Returning to FIG. 2, the wire 37 is made of a conductive member. Three wires 37 are provided on each of the first side (the side where the side surface 32a of the lens holder 32 is present) and the second side (the side where the side surface 32b of the lens holder 32 is present) so as to sandwich the lens holder 32. A total of six are provided. One end of each wire 37 is soldered to a relay substrate 39 provided in the lens holder 32 (only one is shown in FIG. 2, but another is provided at a position facing the lens holder 32). Fixed.

  Note that a wiring pattern is formed on the relay board 39, and the upper two wires 37 are electrically connected to a focus coil (not shown) via the relay board 39. . The two lower wires 37 are electrically connected to the tracking coil 38 via the relay substrate 39.

  Of the wires 37, the upper and lower four wires 37 in total are provided so that the other end passes through a through-hole 352 formed in the rigid printed board 35 and is fixed by soldering. On the other hand, the two wires 37 in the middle stage are provided so that the other end passes through a through hole 364 formed in the flexible printed circuit board 36, and are fixed by soldering.

  In the present embodiment, the size of the through hole 364 formed in the flexible printed circuit board 36 is larger than that of the through hole 352 formed in the rigid printed circuit board 35. This is because the wire 37 is divided into two parts, that is, a rigid printed board 35 and a flexible printed board 36, so that a positional shift occurs between the two parts and the assembly may be difficult. Is taken into account. That is, with the configuration of the present embodiment, it is possible to reduce the possibility that assembly is difficult even if the above-described misalignment occurs.

  By configuring the wire 37 as described above, the lens holder 32 is supported by the wire 37 so as to be swingable with respect to the base 31. Each wire 37 is inserted through an insertion hole 34 a formed in the gel holder 34. As a result, vibration (mainly low-order resonance) generated in each wire 37 in accordance with the driving of the lens holder 32 can be attenuated.

(Operation of the objective lens actuator)
Next, the operation of the objective lens actuator 30 configured as described above will be described.

  A current according to a signal from the control unit is supplied to the focus coil via the flexible printed circuit board 36, the rigid printed circuit board 35, and the upper wire 37. In this case, the lens holder 32 is displaced in the focus direction by the electromagnetic action of the current flowing through the focus coil and the magnetic field formed by the pair of permanent magnets 33. For this reason, focusing control can be performed by adjusting the magnitude and direction of the current supplied to the focus coil.

  A current according to a signal from the control unit is supplied to the tracking coil 38 via the flexible printed board 36, the rigid printed board 35, and the lower wire 37. In this case, the lens holder 32 is displaced in the tracking direction by the electromagnetic action of the current flowing through the tracking coil 38 and the magnetic field formed by the pair of permanent magnets 33. Therefore, tracking control can be performed by adjusting the magnitude and direction of the current supplied to the tracking coil 38.

  The objective lens actuator 30 of the present embodiment is configured such that the lens holder 32 is swingably supported by the wire 37. In such a configuration, unnecessary resonance such as pitching resonance or yawing resonance may occur due to use in a high frequency band (for example, 1 kHz to 5 kHz). Such unnecessary resonance cannot be sufficiently suppressed by the gel material of the gel holder 34.

  The pitching resonance is a resonance mode that occurs in the direction around the axis parallel to the tracking direction. Yawing resonance is a resonance mode that occurs in a direction around an axis parallel to the focus direction.

  For this reason, in the objective lens actuator 30 of the present embodiment, as described above, the upper and lower wires 37 are fixed to the rigid printed circuit board 35 having the notch portions 351 at the center on the left and right end sides. Yes. The middle-stage wire 37 is fixed to the second portion 362 of the flexible printed circuit board 36 arranged so that a part of the wire 37 overlaps the notch 351.

  In this case, the rigid printed circuit board 35 and the flexible printed circuit board 36 can vibrate slightly at the portion where the wire 37 is fixed, as in the case where the slit is provided (see FIG. 9B of the conventional example). For this reason, unnecessary resonance can be reduced as shown in FIG. FIG. 5 is a graph showing that unnecessary resonance can be reduced by the objective lens actuator 30 of the present embodiment. Since two objective lens actuators were prepared and their effects were confirmed, two results shown in FIGS. 5A and 5B are shown.

  The effect was confirmed by changing only the configuration of the rigid printed board and the flexible printed board in each objective lens actuator. The result shown as this embodiment in FIG. 5 is the case where the structure of a rigid printed circuit board and a flexible printed circuit board is FIG. On the other hand, the result shown as a comparative example in FIG. 5 is the case where the configuration of the rigid printed board and the flexible printed board is the configuration of FIG.

  In FIG. 5, the horizontal axis represents the AC frequency used when driving the objective lens actuator. The vertical axis is an index representing a delay in response to an input (drive input) in the objective lens actuator and is a phase. FIG. 5 shows the measurement of the change in phase when the frequency is changed. When unnecessary resonance occurs, the phase change with respect to the frequency change also disturbs. Therefore, it is possible to evaluate whether or not unnecessary resonance has been reduced by estimating the amount of phase disturbance. 5 that the unnecessary resonance can be clearly reduced in the configuration of the present embodiment as compared with the comparative example.

  And in the case of this embodiment, the space for providing the slit 103 as shown in FIG.9 (b) is not required. Therefore, according to the objective lens actuator 30 of the present embodiment, unnecessary resonance can be reduced without increasing the size of the apparatus. The optical pickup including the objective lens actuator 30 can stably read and write information, and can reduce the size of the apparatus.

(Other)
The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the object of the present invention.

  For example, in this embodiment, the flexible printed circuit board 36 is directly fixed to the rigid printed circuit board 35. However, in this case, there is a problem that it is difficult to perform a soldering operation between the second land 355 of the rigid printed circuit board 35 and the fourth land 366 of the flexible printed circuit board 36. Therefore, for the purpose of increasing the strength of the flexible printed circuit board 36, a configuration may be adopted in which a reinforcing plate (for example, made of glass epoxy material) 40 is attached to the flexible printed circuit board 36 as shown in FIG. . FIG. 6 is a schematic plan view when the flexible printed circuit board 36 is viewed from the rigid printed circuit board 35 side of FIG.

  FIG. 6A shows a configuration in which the reinforcing plate 40 is provided on the entire first portion 361 and second portion 362 of the flexible printed circuit board 36 (see FIG. 4B). FIG. 6B shows a configuration in which the reinforcing plate 40 is not provided in the vicinity of the portion where the fourth land 366 of the flexible printed circuit board 36 is provided in the configuration of FIG. FIG. 6C shows a configuration in which the reinforcing plate 40 is provided so as to connect the second portions 362 of the flexible printed circuit board 36. FIG. 6D shows a configuration in which the reinforcing plate 40 is provided only on the second portion 362 of the flexible printed circuit board 36.

  The shape of the reinforcing plate 40 may be any one of FIGS. 6A to 6D and may be another shape. What is necessary is just to determine the shape suitably according to a condition. For example, in the case of the configuration of FIG. 6A, the effect of reinforcement is great, but due to the thickness of the reinforcing plate 40, soldering becomes difficult. For this reason, it is also possible to employ a configuration in which the reinforcing plate 40 is not provided at the portion to be soldered as shown in FIG. However, in the case of the configuration shown in FIG. 6B, the structure is complicated, so that the configuration shown in FIG. 6C or FIG. 6D can be used. However, in these configurations, the reinforcing effect may not be sufficiently obtained.

  Further, for example, the configurations of the rigid printed circuit board 35 and the flexible printed circuit board 36 are not limited to the configuration of the present embodiment, and various modifications can be made. That is, for example, as shown in FIG. 7, the four corners of the rigid printed circuit board 35 are cut out (notched portions 351 are formed), only the middle wire 37 is fixed to the rigid printed circuit board 35, and the upper and lower wires are fixed. 37 may be configured to be fixed to the flexible printed circuit board 36. FIG. 7 shows a modified example of a portion composed of a rigid printed board and a flexible printed board.

  In the present embodiment, the lens holder 32 is shown as being supported by a total of six wires 37, three on the first side and three on the second side. Is not limited to the number of the present embodiment. That is, the present invention can be applied to a configuration in which the lens holder is supported by a total of four wires, two on each side, and a configuration in which the lens holder is supported by four or more wires on one side.

  FIG. 8 is a diagram for explaining another configuration to which the present invention can be applied. FIG. 8A shows a configuration example in which the lens holder is supported by a total of four wires, two wires on each side. FIG. 8B is a diagram illustrating a configuration example in the case where the lens holder is supported by a total of ten wires, each having five wires on one side. In any configuration, the rigid printed circuit board 35 is provided with a notch 351, and the portion of the flexible printed circuit board 36 that is fixed to the end of the wire 37 is arranged on the notch 351. . With this configuration, unnecessary resonance can be reduced without increasing the device size of the objective lens actuator.

  In the present embodiment, the flexible printed circuit board 36 is arranged on the outer surface side of the rigid printed circuit board 35. However, the present invention is not limited to this. That is, the flexible printed circuit board 36 may be attached to the gel holder 34 and the rigid printed circuit board 35 may be disposed on the outer surface side of the flexible printed circuit board 36. However, in the case of this configuration, since the thickness of the rigid printed board 35 makes it difficult to perform a soldering operation, the configuration of this embodiment is preferable.

  In the present embodiment, the objective lens actuator 30 is provided with the two objective lenses 17 and 25. However, the present invention is not limited to this, and the present invention is naturally applicable to the case where the number of objective lenses is one or three or more. The present invention is applicable. In the objective lens actuator 30 of the present embodiment, only the upper and lower wires 37 are electrically connected to the coils (focus coil, tracking coil) provided in the lens holder 32. However, the middle wire 37 is used. Alternatively, a configuration in which the coil is electrically connected to a coil provided in the lens holder 32 may be used. As such a case, for example, a case where a tilt coil is provided in the lens holder 32 can be cited. Note that the tilt coil here is a coil for generating an action of rotating the lens holder 32 in the direction around the axis orthogonal to both the focus direction and the tracking direction.

  The objective lens actuator of the present invention can reduce unnecessary resonance such as pitching resonance and yawing resonance without increasing the device size. For this reason, the objective lens actuator of the present invention can be suitably used for an optical pickup.

These are the schematic which shows the structure of the optical system with which the optical pick-up of this embodiment is provided. These are the schematic perspective views which show the structure of the objective-lens actuator of this embodiment. These are the schematic plan views which show the structure of the part which consists of a rigid printed circuit board with which the objective lens actuator of this embodiment is equipped, and a flexible printed circuit board. These are the schematic plan views which decomposed | disassembled the structure shown in FIG. 3, and showed each part. These are graphs showing that unnecessary resonance can be reduced by the objective lens actuator of the present embodiment. These are the figures for demonstrating the modification of the objective-lens actuator of this embodiment. These are modifications of the objective lens actuator of the present embodiment, specifically, a modification of a portion composed of a rigid printed board and a flexible printed board. These are the figures for demonstrating the other structure which can apply this invention. These are explanatory drawings for demonstrating the problem which generate | occur | produces by the structure which provides a slit in a rigid printed circuit board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical pick-up 17 1st objective lens 25 2nd objective lens 30 Objective lens actuator 31 Base 32 Lens holder 35 Rigid printed circuit board 36 Flexible printed circuit board 37 Wire (bar-shaped elastic support member)
40 Reinforcing plate 351 Notch

Claims (5)

Base and
A lens holder for holding the objective lens;
A plurality and the same number are arranged on each of the first side and the second side existing so as to sandwich the lens holder, and one end portion is fixed to the lens holder to swing the lens holder with respect to the base. A rod-like elastic support member that is movably supported;
In an objective lens actuator comprising:
A rigid printed circuit board that is stationary with respect to the base and has a notch;
A flexible printed circuit board fixed to the rigid printed circuit board, and
In each of the first side and the second side, a part of the plurality of rod-like elastic support members has the other end fixed to the rigid printed circuit board, and the rest excluding the part The other end is fixed to the flexible printed circuit board,
In the portion where the other end of the rod-like elastic support member is fixed to the rigid printed board, the flexible printed board is not disposed,
The objective lens actuator, wherein a portion of the flexible printed board to which the other end of the rod-like elastic support member is fixed is disposed on the notch.   The objective lens actuator according to claim 1, wherein a reinforcing plate is attached to a part of the flexible printed board.   The objective lens actuator according to claim 1, wherein the rigid printed circuit board is disposed closer to the front side than the flexible printed circuit board when viewed from the lens holder side.   In each of the first side and the second side, three rod-shaped elastic support members are arranged, and the two outer rod-shaped elastic support members are arranged on the rigid printed circuit board on the other end. 4. The objective lens actuator according to claim 1, wherein the other end is fixed to the flexible printed circuit board in a middle one of the rod-like elastic support members. 5.   An optical pickup comprising the objective lens actuator according to claim 1.

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