JP2007102912A - Optical pickup and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To configure an optical pickup in a small size and to stably drive an objective lens. <P>SOLUTION: Front coils 34L and 34R for focusing partly overlaid on front coils 33L and 33R for tracking, respectively, are attached to the front surface 30A of a lens holder 30 in a swing part 25 of an objective lens driving part 21. Thus, the swing part 25 is precisely moved in the tracking direction and the focusing direction, and the thickness in the vertical direction is suppressed to the necessary minimum. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical pickup and an optical disc apparatus, and is suitably applied to an optical disc apparatus compatible with, for example, the Blu-ray Disc (registered trademark) system.

  2. Description of the Related Art Conventionally, in an optical disc apparatus, information is recorded on an optical disc conforming to a DVD (Digital Versatile Disc) method, a Blu-ray Disc (registered trademark) method, or the like, and information is read from the optical disc. Widely used.

Such an optical disc apparatus has an optical pickup, records information by irradiating the optical beam from the optical pickup to the optical disc, and based on the reflected light reflected by the optical disc. To play information.

  In this optical pickup, a light beam is condensed by an objective lens, and in order to focus the optical beam on a desired track in the signal recording layer of the optical disc, the objective lens is placed close to or in the tracking direction which is the radial direction of the optical disc and the optical disc. It can be driven in two directions of the focus direction which are separated from each other.

  The optical pickup is preferably driven in the focus direction and the tracking direction while maintaining a state parallel to the optical disc so as to focus the light beam on a desired track.

  For this reason, in the optical pickup, a plurality of focusing coils and a plurality of tracking coils are respectively arranged around a lens holder that holds the objective lens, and an actuator is formed by providing a magnet at a position facing these coils. Accordingly, there are some which are made to be driven in the focus direction and the tracking direction in parallel with the optical disc.

  On the other hand, the optical disk device is required to be smaller and lighter, but the size of the optical disk is defined by the standard. Therefore, it is necessary to suppress the thickness of the entire device in order to reduce the size. There is a demand to make the optical pickup thinner.

Therefore, in the optical pickup, two focusing coils and two tracking coils are arranged diagonally around the objective lens, so that thrust is applied to the lens holder from both sides sandwiching the center of gravity of the lens holder. In addition, there has been proposed one in which the optical pickup is thinned and the lens holder is driven in parallel as much as possible (see, for example, Patent Document 1).
Japanese Patent Laying-Open No. 2005-174485 (FIG. 9)

  However, since the optical pickup having such a configuration gives thrust in the focus direction to the lens holder by the two focusing coils positioned asymmetrically in the front-rear direction, a slight amount generated in the lens holder when the lens holder is driven in the focus direction. There is a risk that rolling will occur due to the forward and backward movements and the lens holder will become unstable.

  Similarly, since the optical pickup having such a configuration gives thrust in the tracking direction to the lens holder by two tracking coils positioned asymmetrically in the front-rear direction, yawing is generated even when the lens holder is driven in the tracking direction, There is a risk of destabilizing the lens holder.

  Here, in the optical pickup, when the lens holder becomes unstable, it becomes impossible to accurately focus the light beam on a desired track of the optical disk. There has been a problem that the accuracy of reading information is lowered.

  The present invention has been made in consideration of the above points, and an object of the present invention is to propose an optical pickup and an optical disc apparatus that can be configured in a small size and can stably drive an objective lens.

  In order to solve such a problem, in the optical pickup of the present invention, a lens holder in which one or more objective lenses for condensing the light beam on the signal recording layer of the optical disk are provided, and the lens holder is adjusted in the tracking direction and focus. Based on a predetermined focus control current, a base portion that is swingably supported in each direction, a tracking coil provided on a side surface of the lens holder for driving the lens holder in a tracking direction based on a predetermined tracking control current, and a predetermined focus control current In order to drive the lens holder in the focusing direction, a focusing coil provided on the side surface of the lens holder, and a tracking magnet and a focusing magnet are fixed to the base portion and corresponding to the tracking coil and the focusing coil, respectively. Each retained Provided a chromatography click away central axis of the tracking coil and the focusing coil only parallel a predetermined distance from each other, the coil portion thereof is so provided on the side surface of the lens holder in a state of being partially overlapped.

  Accordingly, the magnetic fields necessary for driving in the focus direction and driving in the tracking direction can be normally generated, and the focusing coil and the tracking coil on the side surface of the lens holder can be arranged close to each other, thereby reducing the size. be able to.

  Further, the optical disk apparatus of the present invention is an optical disk apparatus having an optical pickup that irradiates a desired position in a signal recording layer of the optical disk and a tracking drive unit that drives the optical pickup in the radial direction of the optical disk. The optical pickup includes a lens holder provided with one or more objective lenses for condensing a light beam on the signal recording layer of the optical disc, and the lens holder can swing freely in a tracking direction and a focusing direction. A supporting base, a tracking coil provided on a side surface of the lens holder for driving the lens holder in the tracking direction based on a predetermined tracking control current, and the lens holder in the focus direction based on a predetermined focus control current Provided on the side of the lens holder for driving And a tracking coil and a focusing coil that are fixed to the base, and that are respectively provided with tracking magnets and focusing coils at positions corresponding to the tracking coils and focusing coils. The central axes of the lens holders are parallel to each other and separated from each other by a predetermined distance, and the coil portions are provided on the side surface of the lens holder in a partially overlapped state.

  As a result, the magnetic field required for driving in the focus direction and tracking direction in the optical pickup can be generated normally, and the focusing coil and tracking coil on the side surface of the lens holder can be arranged close to each other, making it compact. Can be achieved.

  According to the present invention, a magnetic field required for driving in the focus direction and driving in the tracking direction can be normally generated in the optical pickup, and the focusing coil and the tracking coil on the side surface of the lens holder are arranged close to each other. Thus, the optical pickup and the optical disc apparatus can be realized which can be miniaturized and can stably drive the objective lens.

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

(1) Overall Configuration of Optical Disc Device In FIG. 1, an optical disc device 1 is comprehensively controlled by a system controller 2, and as a whole a CD (Compact Disc), a DVD (Digital Versatile Disc) or a Blu-ray Disc (registered trademark) (Hereinafter referred to as “BD”), which reads out data from the optical disc 100 of the system and outputs the decoded video / audio signal to the outside, and writes the encoded data of the video / audio signal input from the outside onto the optical disc 100. Yes.

  When the system controller 2 obtains a data reproduction command from the optical disc 100 based on a user's operation via the operation unit 3 with the optical disc 100 loaded, the system controller 2 records it on the signal recording layer of the optical disc 100. A data read command MR is sent to the drive control unit 4 together with address information IA for specifying data.

The drive control unit 4 controls the spindle motor 5 in accordance with a data read command from the system controller 2 to rotate the optical disc 100 at a predetermined rotation speed.
By controlling the feed motor 6 based on the data read command MR and the address information IA, the optical pickup 7 is moved in the radial direction of the optical disc 100, and address information from the system controller 2 in the signal recording layer of the optical disc 100 is obtained. The laser beam is focused and irradiated on a track corresponding to the above (hereinafter referred to as a desired track).

  At this time, the optical pickup 7 receives the reflected laser light from which the laser light applied to the optical disc 100 is reflected, and sends a received light signal SR corresponding to the amount of light to the signal processing unit 8. Based on the received light signal SR, the signal processing unit 8 performs a tracking error signal STE corresponding to the deviation amount of the irradiation position of the laser beam with respect to the desired track and a focus corresponding to the deviation amount of the focus of the laser beam with respect to the signal recording layer of the optical disc 100. The error signal SFE is generated and sent to the drive control unit 4, and the reproduction RF signal SRF is generated based on the received light signal SR and sent to the signal modulation / demodulation unit 9.

  The drive control unit 4 generates a tracking control signal CT and a focus control signal CF based on the tracking error signal STE and the focus error signal SFE, and sends them to the optical pickup 7. In response to this, the optical pickup 7 performs tracking control and focus control so as to focus the laser beam on a desired track of the optical disc 100 (details will be described later).

  The signal modulation / demodulation unit 9 generates reproduction data DP by performing predetermined demodulation processing, decoding processing, and the like on the reproduction RF signal SRF, and sends the reproduction data DP to the D / A and A / D converter 11. Based on the reproduction RF signal SRF, a laser power signal SLP is generated and sent to the laser controller 10.

  The laser control unit 10 generates a laser power control signal CLP based on the laser power signal SLP and sends it to the optical pickup 7. In response to this, the optical pickup 7 controls the intensity of laser light emitted from a laser diode (not shown) so as to match the intensity suitable for reproduction.

  The D / A and A / D converter 11 converts the reproduction data DP into an analog video / audio signal SAV and sends it to the input / output processing unit 12. The input / output processing unit 12 performs signal processing such as level adjustment on the video / audio signal SAV, and then sends the video / audio signal SAV to an external monitor (not shown), whereby video and audio corresponding to the video / audio signal SAV are transmitted. Is to be viewed by the user.

  When the system controller 2 obtains a data recording command to the optical disc 100 based on a user operation via the operation unit 3 with the optical disc 100 loaded, the system controller 2 records the data on the signal recording layer of the optical disc 100. A data write command MW is sent to the drive control unit 4 together with address information IA for designating a location to be performed.

  Further, the system controller 2 causes the input / output processing unit 12 to perform predetermined level conversion processing or the like on the video / audio signal SAV input from an external device (not shown), etc. 11 is converted into recording data DR, and the signal modulation / demodulation unit 9 performs encoding processing, modulation processing, and the like to generate write data DW, which is sent to the optical pickup 7. Further, the drive control unit 4 controls the position of the optical pickup 7 based on the address information IA.

  In response to this, the optical pickup 7 focuses the light beam on the track corresponding to the address information IA in the signal recording layer of the optical disc 100, and the laser is adjusted to an intensity suitable for data recording under the control of the laser control unit 10. The write data DW is written on the optical disc 100 by irradiating light.

  As described above, the optical disc apparatus 1 can record and reproduce data by irradiating a focused laser beam on a desired track in the signal recording layer of the optical disc 100 from the optical pickup 7.

(2) Configuration of Optical Pickup As shown in FIGS. 2 and 3, the optical pickup 7 is configured around a slide base 20 that is flat as a whole, and an objective lens is attached to the slide base 20. An objective lens drive unit 21 (described in detail later) that drives in two directions, the tracking direction and the focus direction, and a reflected light that supplies the laser beam to the objective lens drive unit 21 and is reflected by the optical disc 100 And an optical circuit unit 22 for detecting the above.

  In the following description, the optical circuit unit 22 side of the slide base 20 is the front direction, the objective lens driving unit 21 side is the rear direction, and the objective lens of the objective lens driving unit 21 is directed leftward and rightward with the objective lens facing upward. It will be explained after defining.

  The slide base 20 is provided with shaft holes 20A and 20B penetrating in the left-right direction on the rear side, and a cylindrical slide shaft (not shown) is inserted through the shaft holes 20A and 20B. The slide shaft is attached to the housing of the optical disc apparatus 1 in parallel with the radial direction of the optical disc 100.

  Further, a guide portion 20 </ b> C having a substantially U-shaped side surface is provided on the front side of the slide base 20. The guide portion 20C is adapted to be screwed into a spiral groove carved into a cylindrical rotary shaft (not shown) that is rotationally driven by the feed motor 6 (FIG. 1).

  In practice, the slide base 20 is rotationally driven by the feed motor 6 (FIG. 1), so that the inner periphery side (left direction) or the outer periphery side (right direction) of the optical disc 100 along the rotation shaft and slide shaft. ) In the radial direction (that is, the tracking direction).

  The optical circuit section 22 is arranged such that optical components such as a laser diode, a photodetector, and a prism (not shown) form a predetermined optical path. In practice, a blue-violet laser beam (wavelength of about 405 [nm] corresponding to BD is used. ]) And red light (wavelengths of about 780 [nm] and about 650 [nm]) corresponding to CD and DVD can be emitted and received.

(3) Configuration of Objective Lens Drive Unit As shown in FIGS. 4 and 5, the objective lens drive unit 21 swings the swing unit 25 having the objective lens through the suspension wires 24 </ b> A to 24 </ b> D by the support unit 23. It is designed to be freely supported.

  The support portion 23 is attached and fixed to the slide base 20 (FIGS. 2 and 3), and rear end portions of the four suspension wires 24A to 24D are respectively attached to predetermined positions.

  The suspension wires 24 </ b> A to 24 </ b> D are made of a metal material having elasticity, and the front end portion is attached to the lens holder 25, so that the swinging portion 25 can swing substantially vertically and horizontally. Yes.

  The suspension wires 24A to 24D electrically connect the support portion 23 and the lens holder 25, respectively, and currents that flow through a focus coil and a tracking coil (details will be described later) provided on the swing portion 25. (That is, the tracking control signal CT and the focus control signal CF) are transmitted.

  A yoke 26 having a predetermined shape for holding a plurality of magnets (details will be described later) is provided around the swinging portion 25. The yoke 26 is fixedly attached to the support portion 23, and as a result, is fixed to the slide base 20.

(3-1) Configuration of Oscillating Unit As shown in FIGS. 6 and 7, the oscillating unit 25 is mainly configured by a lens holder 30 formed by molding a resin material into a box shape with the bottom surface released. Has been.

  A CD / DVD objective lens 31 is attached and fixed to the front side 30A of the lens holder 30 and a BD objective lens 32 is attached and fixed to the rear side. Circular holes are respectively provided at locations corresponding to the BD objective lens 32.

  The front surface 30B of the lens holder 30 is formed with a notch 30B1 having a large lower notch at the left and right central portions, and a light beam is allowed to pass through the notch 30B1.

  2 and 3, when the objective lens driving unit 21 is attached to the slide base, the lens holder 30 is provided with an upright mirror (attached to the upright mirror attaching portion 20D of the slide base 20). (Not shown).

  Actually, the oscillating unit 25 (FIGS. 6 and 7) cuts the laser light emitted from the optical circuit unit 22 (FIGS. 2 and 3) according to the type (CD, DVD or BD) of the optical disc 100. The laser beam is reflected upward by a rising mirror covered by the lens holder 30 through the notch 30B1, and the laser light is condensed by the CD / DVD objective lens 31 or the BD objective lens 32 to irradiate the optical disc 100. It is made like that.

  The oscillating unit 25 returns the reflected laser light reflected by the optical disc 100 to parallel light by the CD / DVD objective lens 31 or the BD objective lens 32, and directs it to the front by a rising mirror. It is made to enter into the optical circuit part 22 through the notch part 30B1.

  Front tracking coils 33L and 33R are attached to the front surface 30B of the lens holder 30 so that the respective central axes (not shown) are directed in the front-rear direction on the left and right sides of the notch 30B1. Focus front coils 34L and 34R are attached to the left and right sides at positions where the front coils 33L and 33R are shifted from the central axis by a predetermined distance and are partially overlapped with the tracking front coils 33L and 33R when viewed from the front side. It has been.

  The focus front coils 34L and 34R are attached to the left and right sides of the notch 30B1 when viewed from the front side, and are located at the lowest side of the swinging unit 25 and the front side.

  The tracking front coils 33L and 33R have a central axis substantially the same height as the center of gravity of the oscillating portion 25, and the central axes are located outside the central axes of the focusing front coils 34L and 34R in the left-right direction, respectively. In addition, it is attached at a position immediately behind the focusing front coils 34L and 34R in the front-rear direction.

  Further, the tracking front coils 33L and 33R are thicker than the focusing front coils 34L and 34R, respectively, and have a larger number of turns, and can form a stronger magnetic field than the focusing front coils 34L and 34R. ing.

  On the other hand, a rear coil for tracking 35 is attached to the rear surface 30C of the lens holder 30 at the center of the left and right sides, and for focusing on the left and right sides so as not to overlap with the rear coil for tracking 35 when viewed from the rear side. Rear coils 36L and 36R are attached.

  The focusing rear coils 36L and 36R are attached to positions that are substantially symmetrical with respect to the focusing front coils 34L and 34R, that is, at the lowest position and the rearmost position of the swing portion 25, respectively.

  Incidentally, the focusing front coils 34L and 34R and the focusing rear coils 36L and 36R are attached to the lowermost position of the swinging portion 25, so that the CD / DVD objective lens 31 and the relatively heavy weight lens 31 and A weight balance with the BD objective lens 32 is achieved.

  Like the tracking front coils 33L and 33R, the tracking rear coil 35 has a center axis that is substantially the same as the height of the center of gravity of the oscillating portion 25, the rearmost side of the oscillating portion 25, and the left-right direction. Only one is attached at the center position.

  Further, on the side surface of the lens holder 30, grooves 30DA to 30DD are provided for fitting the front end portions of the suspension wires 24A to 24D each having the rear end portion attached to the support portion 23 (FIGS. 4 and 5). .

  The lens holder 30 is fixed to the suspension wires 24A to 24D by being filled with a predetermined adhesive in a state where the front end portions of the suspension wires 24A to 24D are fitted into the grooves 30DA to 30DD, respectively. ing.

  Here, as shown in FIGS. 8 and 9 corresponding to FIGS. 4 and 5 and omitting the yoke 26, the swinging portion 25 is supported by the suspension wires 24A to 24D from the rear side. For this reason, in the lens holder 30, when two tracking coils are attached to the rear surface 30C at the same position as the front surface 30B, the tracking coils interfere with the suspension wires 24A to 24D. .

  Therefore, the swinging portion 25 is configured to avoid interference with the suspension wires 24 </ b> A to 24 </ b> D by providing one tracking coil on the rear surface 30 </ b> C of the lens holder 30 instead of two on the left and right sides.

  Incidentally, since the swinging portion 25 is supported from the rear side by the suspension wires 24A to 24D, when moving in the left-right direction, the movement amount on the rear side is larger than that on the front side and moves in a so-called pendulum shape. Therefore, the tracking rear coil 35 has a larger number of turns than the tracking front coils 33L and 33R in consideration of the balance with the tracking front coils 33L and 33R and the movement of the pendulum.

  The tracking front coils 33L and 33R, the focusing front coils 34L and 34R, the tracking rear coil 35, and the focusing rear coils 36L and 36R are electrically connected to the suspension wires 24A to 24D, respectively. A current (that is, tracking control signal CT and focus control signal CF) is supplied from the mounting portion 23 (FIGS. 4 and 5) via the wires 24A to 24D, thereby forming a magnetic field.

  As described above, the oscillating portion 25 is provided with the notch 30B1 on the front surface 30B of the lens holder 30, and the focusing front coils 34L and 34R are respectively attached to the tracking front coils 33L and 33R so as to partially overlap each other. In addition, on the rear surface 30C of the lens holder 30, one tracking rear coil 35 is attached at the center and two focus rear coils 36L and 36R are attached to the left and right, respectively.

(3-2) Configuration of Yoke As shown in FIGS. 10, 11 and 12, the yoke 26 is configured by cutting a metal flat plate into a predetermined shape and bending it into a substantially U-shaped side surface. By forming a space that is slightly larger than the swinging portion 25 (FIGS. 6 and 7), the swinging portion 25 can be swung inside.

The bottom surface 26 </ b> A of the yoke 26 is greatly cut out at the center portion except for the right side and the left side, and when the objective lens driving unit 21 (FIGS. 2 and 3) is attached to the slide base 20,
The upright mirror mounting portion 20D, the support portions 20E1 and 20E2 (FIG. 3) that support the upright mirror mounting portion 20D, and the upright mirror (not shown) attached to the upright mirror mounting portion 20D. Has been made.

  Like the front surface 30A of the lens holder 30, the front surface 26B of the yoke 26 is cut out at the lower center portion so that the laser beam can pass therethrough. Further, as shown in FIG. 10, on the inner surface side (that is, the rear surface) of the front surface 26B, the focusing portion is positioned at a position corresponding to the focusing front coils 34L and 34R of the swing portion 25 (FIGS. 6 and 7). Front magnets 41L and 41R are respectively attached, and tracking front magnets 40L and 40R are respectively attached at positions corresponding to the tracking front coils 33L and 33R.

  As shown in FIG. 13, on the left side of the front surface 26B of the yoke 26, the focusing front magnet 41L and the tracking front magnet 40L are attached in close contact with each other.

  Here, the focusing front magnet 41L is magnetized so that the upper side is an N pole and the lower side is an S pole, and the tracking front magnet 40L is a surface facing the tracking front coil 33L (that is, in FIG. 13). The shown surface, hereinafter referred to as the rear surface, is an S pole, and the opposite side (ie, the front surface) is magnetized so as to be an N pole.

  In this case, the yoke 26 forms a magnetic field for focusing in the vertical direction by the upper N pole and the lower S pole of the focusing front magnet 41L, and also tracks the upper N pole of the focusing front magnet 41L. A tracking magnetic field (hereinafter referred to as a tracking front magnetic field) is formed in the left-right direction by the S pole on the rear surface of the front magnet 40L.

  Further, the tracking front magnet 40L is formed in substantially the left-right direction without tilting the tracking magnetic field by adjusting the mounting position in the vertical direction in advance.

  Incidentally, a front magnet 41R for focusing and a front magnet 40R for tracking are attached to the right side of the front surface 26B of the yoke 26 so as to be symmetrical with the left side (FIG. 13).

  On the other hand, on the inner surface side of the rear surface 26C of the yoke 26, as shown in FIG. 11, the tracking rear magnet 42 is located at the position corresponding to the tracking rear coil 35 of the swinging portion 25 (FIGS. 6 and 7). The focus rear surface magnets 43L and 43R are mounted at positions corresponding to the focus rear surface coils 36L and 36R of the swinging portion 25 on the left and right sides thereof.

  The tracking rear magnet 42 is attached so that the left side is an N pole and the right side is an S pole, thereby forming a tracking magnetic field in the left-right direction. Similarly to the focusing front magnets 41L and 41R, the focusing rear magnets 43L and 43R are attached so that the upper side is an N pole and the lower side is an S pole, respectively, so that a focusing magnetic field is formed in the vertical direction.

  By the way, the bottom 26A of the yoke 26 has the bottom end portions 26A1 to 26A4 in the vicinity of the front magnets 41L and 41R for focusing and the rear magnets 43L and 43R for focusing dropped downward by a predetermined height from the other portions. Yes.

  Thus, the yoke 26 can extend the focusing front magnets 41L and 41R and the focusing rear magnets 43L and 43R downward as compared with the case where the bottom portion 26A is formed flat.

  Incidentally, the slide base 20 (FIG. 3) is provided with holes 20F1 to 20F4 in portions corresponding to the bottom ends 26A1 to 26A4 of the yoke 26 so as not to interfere with the bottom ends 26A1 to 26A4. .

  The slide base 20 supports the upright mirror mounting portion 20D by the left and right support portions 20E3 and 20E4. Correspondingly, the yoke 26 (FIGS. 10 to 12) does not drop the portions other than the bottom end portions 26A1 to 26A4 of the bottom portion 26A downward, and thus does not interfere with the support portions 20E3 and 20E4. It is made like that.

  As described above, the yoke 26 includes the tracking front coils 33L and 33R, the focusing front coils 34L and 34R, the tracking rear coil 35, and the focusing rear coil 36L attached to the swinging portion 25 (FIGS. 6 and 7). And 36R, tracking front magnets 40L and 40R, focusing front magnets 41L and 41R, tracking rear magnet 42, and focusing rear magnets 43L and 43R are attached, respectively. A magnetic field or a magnetic field for focusing is formed.

  As a result, the objective lens driving unit 21 supplies current (that is, tracking control signal CT) to the tracking front coils 33L and 33R and the tracking rear coil 35 attached to the swing unit 25 (FIGS. 6 and 7). In this case, the generated magnetic field, the tracking front magnetic field, and the magnetic field generated by the tracking rear magnet 42 generate a thrust in the left-right direction with respect to the oscillating unit 25, and the oscillating unit 25 is moved in the tracking direction. Can be driven.

  The objective lens driving unit 21 generates the current when the current (focus control signal CF) is supplied to the focusing front coils 34L and 34R and the focusing rear coils 36L and 36R attached to the swing unit 25, respectively. The magnetic field generated by the generated magnetic field and the magnetic fields generated by the focusing front magnets 41L and 41R and the focusing rear magnets 43L and 43R generate a vertical thrust with respect to the oscillating unit 25, thereby causing the oscillating unit 25 to move in the focusing direction. Can be driven to.

(4) Operation and Effect In the above configuration, the optical pickup 7 of the optical disc apparatus 1 has a notch portion with respect to the front surface 30A of the lens holder 30 in the swinging portion 25 (FIGS. 6 and 7) of the objective lens driving portion 21. The focusing front coils 34L and 34R are respectively attached to the tracking front coils 33L and 33R so as to sandwich the 30A1 from both sides.

  Accordingly, the optical pickup 7 of the optical disc apparatus 1 has the swinging movement compared to the case where the tracking front coils 33L and 33R and the focusing front coils 34L and 34R are attached to the swinging part 25 without overlapping each other. Since the coils can be mounted close to each other on the side surface of the portion 25, the area required for mounting the coils can be reduced, and the swinging portion 25 can be downsized.

  At this time, since the optical pickup 7 can partially overlap the focusing front coils 34L and 34R and the tracking front coils 33L and 33R to reduce the area required for mounting each coil, the swinging portion 25 is made large. Without securing the area required for mounting the notch 30B1 and the suspension wires 24A to 24D on the peripheral side surface (that is, the front surface 30B, the rear surface 30C, the left surface, and the right surface) of the lens holder 30, Three or more focusing coils can be attached to each other, and the oscillating portion 25 can be made extremely small, and can be stably driven in the tracking direction and the focusing direction.

  In practice, in the optical pickup 7 of the optical disc apparatus 1, current (that is, the tracking control signal CT) is supplied to the tracking front coils 33L and 33R of the swinging portion 25 (FIGS. 6 and 7) of the objective lens driving portion 21. In this case, magnetic fields are generated around the tracking front coils 33L and 33R, respectively, and the magnetic field, the upper portions of the focusing front magnets 41L and 41R, and the tracking front magnets 40L and 40R are formed. Thrust is generated by the action of the tracking magnetic field.

  At the same time, when an electric current is supplied to the tracking rear coil 35 of the oscillating unit 25 in the objective lens driving unit 21, the optical pickup 7 generates a magnetic field around the tracking rear coil 35 and the tracking rear magnet. The thrust with respect to the swinging portion 25 is generated by the action of the magnetic field for tracking formed by 42.

  As a result, the optical pickup 7 applies a leftward or rightward thrust to the swinging part 25 of the objective lens driving part 21 as a resultant force of each thrust, and causes the swinging part 25 to move leftward or rightward. It can be driven substantially parallel to (that is, the tracking direction).

  At this time, since the objective lens driving unit 21 has the focusing front coils 34L and 34R and the tracking front coils 33L and 33R overlapped when viewed from the front side, the vertical height and the left and right sides of the swinging unit 25 are arranged. The width of the direction can be suppressed, and it is possible to contribute to downsizing of the rocking part 25 and the optical pickup 7 as a whole.

  Further, the tracking front coils 33L and 33R are mounted for focusing by a distance corresponding to the thickness of the focusing front coils 34L and 34R because the focusing front coils 34L and 34R are attached so as to partially overlap the front side coils. Although the magnetic force is weakened due to separation from the front magnets 41L and 41R and the tracking front magnets 40L and 40R, the thrust required for tracking can be generated by increasing the number of turns to increase the generated magnetic field. .

  Further, since the tracking front coils 33L and 33R and the tracking rear coil 35 are all mounted at the same height as the center of gravity of the swinging portion 25, they are generated when the swinging portion 25 is driven in the left-right direction. The thrust force to be adjusted can be adjusted to substantially the same height as the center of gravity, the swinging portion 25 can be stably moved, and the occurrence of unnecessary vibration can be prevented in advance.

  In addition, since only one tracking rear coil 35 is provided at substantially the center in the left-right direction, the interference with the suspension wires 24 </ b> A to 24 </ b> D in the case where one is provided on the left and right similarly to the front side. It can be prevented in advance.

  Further, the optical pickup 7 generates a magnetic field by supplying current (that is, a focus control signal CF) to the focusing front coils 34L and 34R and the focusing rear coils 36L and 36R of the oscillating unit 25 in the objective lens driving unit 21. In this case, a thrust is generated by the action of the focusing front magnets 41L and 41R and the focusing magnetic fields formed by the focusing rear magnets 43L and 43R, respectively.

  As a result, the objective lens drive unit 21 applies an upward or downward thrust to the swing unit 25 as a resultant force of each magnetic force, and causes the swing unit 25 to move upward or downward (that is, in the focus direction). Can be driven to.

  In this case, the objective lens driving unit 21 moves the focus front coils 34L and 34R and the focus rear coils 36L and 36R from the four locations in the focus direction in substantially the same height in the swing unit 25 in the vertical direction. Since each of the thrusts is applied, the swinging portion 25 is moved in the focus direction in a state of being significantly stable as compared to the case where the thrust is applied diagonally to the swinging portion 25 from two locations. Can do.

  Further, the objective lens driving unit 21 causes the center of thrust generated by the focusing front coils 34L and 34R and the focusing rear coils 36L and 36R to substantially coincide with the center of gravity of the swinging unit 25 in the left-right direction and the front-rear direction. Therefore, it is possible to prevent the occurrence of unnecessary vibration when the swinging portion 25 is driven.

In addition, the objective lens driving unit 21 is the lowest part of the lens holder 30, that is, the swinging unit 25.
The focus front coils 34L and 34R and the focus rear coils 36L and 36R are disposed at the bottom of the lens, so that the CD / DVD objective lens 31 and BD, which are attached to the upper surface 30A of the lens holder 30, are relatively heavy. Therefore, the height of the center of gravity in the vertical direction of the swinging portion 25 can be made closer to the center, so that the swinging portion 25 can be moved at the time of movement. Stability can be improved.

  By the way, since the strength of the front surface 30B is reduced due to the provision of the notch 30B1, the swinging portion 25 resonates when the front surface 30B is subjected to an upward or downward thrust on the lower end portion of the front surface 30B. There is a possibility that.

  Therefore, the objective lens driving unit 21 considers this resonance in advance, and the mounting positions of the focusing front coils 34L and 34R in the left-right direction are adjusted in advance on the front surface 30B of the lens holder 30. It can be prevented in advance.

  Further, the objective lens driving unit 21 has tracking control with relatively low required accuracy by disposing the focusing front coils 34L and 34R on the front side of the tracking unit 25 in front of the tracking front coils 33L and 33R. It is possible to achieve higher accuracy by giving priority to focus control that requires relatively high accuracy.

  In addition, the focusing front coils 34L and 34R are configured such that the number of turns is minimized and the thickness thereof is made as thin as possible, so that the tracking front coils 33L and 33R, the tracking front magnets 41L and 41R, etc. Since they can be made as close as possible, the magnetic field generated by the tracking front coils 33L and 33R and the tracking front magnetic field can be effectively acted, and as a result, the thrust required for tracking can be generated.

  Further, the yoke 26 forms not only the focus (up and down direction) magnetic field but also the tracking (left and right direction) magnetic field (that is, the tracking front magnetic field) using the upper N poles of the focus front magnets 41L and 41R. Therefore, the tracking front magnets 40L and 40R can be downsized as compared with the case where an N pole is provided to separately form a tracking magnetic field. Thereby, it is possible to reduce the size of the feed motor 6 (FIG. 1) by contributing to the weight reduction of the optical pickup 7 as a whole.

  In this case, the tracking front magnets 40L and 40R can be formed substantially in the left-right direction without tilting the tracking front magnetic field by adjusting the mounting positions of the focusing front magnets 41L and 41R in advance. As a result, the objective lens driving unit 21 can move the rocking unit 25 substantially in the left-right direction, and can realize highly accurate tracking.

  Further, the yoke 26 has the bottom end portions 26A1 to 26A4 (FIG. 12) in the vicinity of the focusing front magnets 41L and 41R and the focusing rear magnets 43L and 43R being dropped downward from the other portions. Compared with the case where the bottom surface 26A of the yoke 26 is formed flat, the focusing front magnets 41L and 41R and the focusing rear magnets 43L and 43R can be extended downward, and the swinging portion 25 can be moved in the vertical direction. The movable range of can be expanded.

  Actually, the optical disc apparatus 1 is compatible with three types of optical discs 100 such as CD, DVD, and BD. Here, since the wavelength of the laser beam and the aperture ratio of the objective lens are different in these three methods, the optimum distance between the objective lens and the optical disc 100 is greatly different depending on each method.

  Here, in the optical pickup 7 of the optical disc apparatus 1, the front magnets 41L and 41R for focusing and the rear magnets 43L and 43R for focusing are extended downward to widen the movable range of the swinging portion 25 in the vertical direction. Thus, in each of the CD, DVD, and BD systems, the distance between the CD / DVD objective lens 31 and the BD objective lens 32 (that is, the upper surface of the rocking portion 25) and the optical disk 100 is adjusted optimally, and the focus is adjusted. A moving range that can be sufficiently adjusted can be obtained.

  According to the above configuration, the optical pickup 7 of the optical disc apparatus 1 is partially overlapped with the tracking front coils 33L and 33R with respect to the front surface 30A of the lens holder 30 in the oscillating unit 25 of the objective lens driving unit 21. By attaching the focusing front coils 34L and 34R, the swinging portion 25 can be moved with high accuracy in the tracking direction and the focusing direction, and the thickness in the vertical direction can be minimized. .

(5) Other Embodiments In the above-described embodiment, the focusing front coils 34L and 34R are attached to the front side of the tracking front coils 33L and 33R on the front surface 30B of the lens holder 30 of the swing portion 25. Although the case where it did in this way was described, this invention is not restricted to this, You may make it attach the said front coil 34L and 34R for a focus behind the said front coil 33L and 33R for a tracking.

  In the above-described embodiment, the front coils 30L and 34R for focusing on the front surface 30B of the lens holder 30 of the oscillating portion 25 are attached to the inner side in the left-right direction than the front coils 33L and 33R for tracking. Although the present invention is not limited to this, the focusing front coils 34L and 34R may be attached outside the tracking front coils 33L and 33R. In this case, the resonance of the lens holder 30 is suppressed. If it is a position like

  Further, in the above-described embodiment, the case where the front coils 34L and 34R for focusing and the rear coils 36L and 36R for focusing are attached to the lowermost part of the lens holder 30 has been described, but the present invention is not limited to this. The focusing front coils 34L and 34R and the focusing rear coils 36L and 36R may be attached to the center or upper part of the lens holder 30 in the vertical direction.

  Further, the vertical heights of the focusing front coils 34L and 34R and the focusing rear coils 36L and 36R may not be aligned with the swinging portion 25. In this case, it is desirable to adjust the number of turns of each coil in advance so that the thrust acting on the swinging portion 25 is directed substantially upward or substantially downward.

  Further, in the above-described embodiment, the tracking front coils 33L and 33R and the tracking rear coil 35 are all attached at substantially the same height as the center of gravity of the swinging portion 25 in the vertical direction of the swinging portion 25. However, the present invention is not limited to this, and the tracking front coils 33L and 33R and the tracking rear coil 35 may be attached at different heights from the center of gravity of the swinging portion 25, respectively. At this time, the height of each coil may be different.

  In this case, the height of the tracking front coils 33L and 33R and the tracking rear coil 35, the number of turns of the coil, and the like are adjusted in advance, so that the resultant force of the generated thrust is almost equal to the center of gravity of the oscillating portion 25. It is desirable to match.

Further, in the above-described embodiment, the case where the tracking rear coil 35 attached to the swing portion 25 is one and the focusing rear coils 36L and 36R are one each on the left and right is described. The invention is not limited to this. For example, one tracking rear coil is provided on each of the left and right sides, one focusing rear coil is provided, or one tracking rear coil and one focusing rear coil are provided. As long as each coil does not interfere with the suspension wires 24A to 24D.

  In this case, it is only necessary to apply thrust from three or more places around the rocking part 25 with respect to each of focus and tracking, and thereby give a stable thrust to the rocking part 25 during movement. Can do.

  Further, in the above-described embodiment, the case where the focusing coil and the tracking coil are attached to the front surface of the oscillating portion 25 is described. However, the present invention is not limited to this, and the oscillating portion is not limited thereto. A focusing coil and a tracking coil may be mounted on the rear surface or side surface of the portion 25 in an overlapping manner, or these may be combined.

  Further, in the above-described embodiment, the case where the bottom 26A of the yoke 26 has the shape shown in FIGS. 10 to 12 has been described. However, the present invention is not limited to this, and the focus is long in the vertical direction. It may have various shapes that hold the front magnets 41L and 41R and the focusing rear magnets 43L and 43R and that do not interfere with the support portions 20E1 to 20E4 that support the rising mirror mounting portion 20D of the slide base 20.

  In this case, the thickness of the entire optical pickup 7 may be suppressed by appropriately providing holes such as holes 20F1 to 20F4 (FIG. 3) in the slide base 20 according to the shape of the yoke 26. . Furthermore, the bottom surface 26A of the yoke 26 may not protrude downward depending on the vertical lengths of the focusing front magnets 41L and 41R and the focusing rear magnets 43L and 43R. It is only necessary to obtain a moving distance in the focus direction that can correspond to all methods of CD, DVD, and BD.

  Further, in the above-described embodiment, the case where the magnetic pole of the magnet attached to the front side is as shown in FIG. 13 has been described. However, the present invention is not limited to this, and the magnetic pole is opposite to that in FIG. You may do it. The tracking rear magnet 42 may have an S pole on the left side and an N pole on the right side. Further, the rear magnets 43L and 43R for focusing may have an S pole on the upper side and an N pole on the lower side. Anyway. In this case, the magnetic poles may be different from each other on the front and rear sides or on the left and right sides.

  Furthermore, in the above-described embodiment, the case where each magnet is configured in a substantially rectangular parallelepiped shape has been described, but the present invention is not limited to this, for example, the magnet has a hexahedral shape in which the front and rear surfaces are trapezoidal, You may make it be the arbitrary shapes which can form a desired magnetic field, such as making it a pentahedron whose front and rear surfaces are triangular.

  Further, in the above-described embodiment, the case where the two objective lenses of the CD / DVD objective lens 31 and the BD objective lens 32 are attached to the upper surface 30A of the lens holder 30 has been described. For example, one objective lens corresponding to CD / DVD / BD may be attached, or three or more objective lenses may be attached like CD, DVD and BD.

  Further, in the above-described embodiment, the case where the oscillating unit 25 is translated in the vertical direction (focus direction) and the horizontal direction (tracking direction) in the objective lens driving unit 21 has been described. The invention is not limited to this, and a rotation axis in the front-rear direction may be provided on the support portion 23 of the objective lens driving unit 21 so as to tilt left and right (tilt direction) around the rotation axis.

  Furthermore, in the above-described embodiment, the description has been given of the case where the notch 30B1 through which the laser beam is passed is provided on the front surface 30B of the lens holder 30, but the present invention is not limited to this, and the notch through which the laser beam passes May be provided on other surfaces such as the left and right side surfaces and the rear surface.

  Furthermore, in the above-described embodiment, the case where the suspension wires 24A to 24D are made substantially linear has been described. However, the present invention is not limited to this, and for example, the protruding portion of the swing portion 25 or the swing portion. 25 may be bent into a shape that avoids interference with the tracking coil attached to 25, or may be bent in an arc shape.

  Further, in the above-described embodiment, the case where the optical disc apparatus 1 is adapted to the three types of optical discs 100 having different wavelengths of light beams to be used, such as CD, DVD, and BD, has been described. For example, the optical disc apparatus 1 may be adapted to support only BD (that is, only one method), BD / DVD only (that is, two methods), or may correspond to an optical disc 100 of four or more methods. good.

  Furthermore, in the above-described embodiment, the lens holder 30 as a lens holder, the support portion 23 as a base portion, tracking front coils 33L and 33R as tracking coils, and a focus front coil as a focus coil. Although the case where the optical pickup 7 as the optical pickup is configured by the 34L and 34R and the yoke 26 as the yoke has been described, the present invention is not limited to this, and a lens holder having various other configurations, a base portion, An optical pickup may be configured by the tracking coil, the focusing coil, and the yoke.

  The present invention can also be used in various optical disk devices corresponding to various types of optical disks.

1 is a block diagram showing an overall configuration of an optical disc apparatus according to a position embodiment of the present invention. It is a rough-line perspective view from the front upper right which shows the structure (1) of an optical pick-up. It is a rough-line perspective view from the rear lower right which shows the structure (2) of an optical pick-up. It is a rough-line perspective view from the front upper right which shows the structure (1) of an objective lens drive part. It is a rough-line perspective view from the rear lower right which shows the structure (2) of an objective lens drive part. It is a rough-line perspective view from the front upper right which shows the structure (1) of a rocking | swiveling part. It is a rough-line perspective view from the rear lower right which shows the structure (2) of a rocking | swiveling part. It is a rough-line perspective view from the front upper right which shows the relationship (1) of a lens holder and a suspension wire. It is a rough-line perspective view from the lower right rear side which shows the relationship (2) of a lens holder and a suspension wire. It is a rough-line perspective view from the rear upper right which shows the structure (1) of a yoke. It is a rough-line perspective view from the front upper right which shows the structure (2) of a yoke. It is a rough-line perspective view from the rear lower right which shows the structure (3) of a yoke. It is a basic diagram with which it uses for description of formation of the magnetic field in the front side of a yoke.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical disk apparatus, 2 ... System controller, 4 ... Drive control part, 6 ... Feed motor, 7 ... Optical pick-up, 20 ... Slide base, 21 ... Objective lens drive part, 22 ... Optical circuit Part 23... Support part 24 A to 24 D suspension wire 25. Swing part 26. Yoke 26 A bottom 26 A 1 to 26 A 4 bottom end 30 lens holder 30 A ... upper surface, 30B ... front face, 30B1 ... notch, 30C ... rear face, 31 ... objective lens for CD / DVD, 32 ... objective lens for BD, 33L, 33R ... front coil for tracking, 34L, 34R …… Focus front coil, 35 …… Tracking rear coil, 36L, 36R …… Focus rear coil, 40L, 40R …… Tracking front magnet DOO, 41L, 41R ...... focusing front magnet 42 ...... tracking rear magnet, 43L, 43R ...... focusing rear magnet, CT ...... tracking control signal, CF ...... focus control signal.

Claims (13)

A lens holder in which one or more objective lenses for condensing the light beam on the signal recording layer of the optical disc are provided on the upper surface;
A base portion that supports the lens holder so as to be swingable in a tracking direction and a focusing direction, and
A tracking coil provided on a side surface of the lens holder for driving the lens holder in the tracking direction based on a predetermined tracking control current;
A focusing coil provided on a side surface of the lens holder for driving the lens holder in the focusing direction based on a predetermined focus control current;
A yoke fixed to the base portion, and holding a tracking magnet and a focusing magnet at positions corresponding to the tracking coil and the focusing coil, respectively.
An optical pickup comprising: a central axis of the tracking coil and the focusing coil being parallel to each other and separated from each other by a predetermined distance, and the coil portions being partially overlapped and provided on a side surface of the lens holder. The focusing coil is
Provided on each of the left and right sides of the notch on the front surface of the lens holder;
The tracking coil is
The left side and the right side of the notch on the front surface of the lens holder, which are partially overlapped with the focusing coil, respectively, and the central axis of the focusing coil is located outside the central axis of the focusing coil The optical pickup according to claim 1, wherein the optical pickup is attached. The lens holder is
A notch portion having a predetermined shape for allowing the light beam to pass therethrough is provided on the front surface,
The focusing coil is
3. The light according to claim 2, wherein the light is attached at a position adjusted in advance so as to suppress resonance that occurs when the lens holder is driven in a focus direction due to the provision of the notch. pick up. One or more rear surfaces of the lens holder, and a tracking rear coil for driving the lens holder in the left-right direction in cooperation with the tracking coil;
One or more provided on the rear surface of the lens holder, and the rear coil for focusing for driving the lens holder in the vertical direction in cooperation with the focusing coil;
The yoke is
The optical pickup according to claim 2, wherein the tracking rear magnet and the focusing rear magnet are respectively held at positions corresponding to the tracking rear coil and the focusing rear coil. 5. The optical pickup according to claim 4, wherein at least one of the tracking rear coil or the focusing rear coil is provided at substantially the center of the rear surface of the lens holder. The tracking rear coil is provided only at the center of the rear surface of the lens holder.
6. The optical pickup according to claim 5, wherein the focusing rear coil is provided on each side of the tracking rear coil provided on the rear surface of the lens holder. The tracking rear coil is
The thrust that acts between the tracking control current and the tracking rear magnet is the sum of the two thrusts that act between the tracking coil and the tracking magnet respectively provided on the left and right of the front surface. The optical pickup according to claim 6, wherein the size and the number of turns are adjusted so as to be substantially the same size. The tracking coil is
The optical pickup according to claim 1, wherein each of the thrusts acting on the lens holder is directed substantially in the tracking direction by being attached at a height substantially equal to the center of gravity of the lens holder. The yoke is
2. The optical pickup according to claim 1, wherein the tracking magnet and the focusing magnet are held adjacent to each other and adjusted to form a magnetic field in the tracking direction. The focusing magnet is
It has a substantially rectangular parallelepiped shape and two magnetic poles that are different in the vertical direction,
The tracking magnet is
It has a substantially rectangular parallelepiped shape and a single magnetic pole,
The yoke is
The magnetic pole of the surface facing the tracking coil of the tracking magnet becomes a magnetic pole opposite to the magnetic pole of the adjacent portion of the focusing magnet, and the focusing magnet of the portion adjacent to the tracking magnet moves in the focusing direction. The optical pickup according to claim 9, wherein the tracking magnet and the focusing magnet are held so as to form both a magnetic field and a magnetic field in the tracking direction. The yoke is
The optical pickup according to claim 1, wherein a movable range in the focus direction of the lens holder is extended by projecting a portion holding the focusing magnet downward. The lens holder is
The optical pickup according to claim 1, comprising two types of lenses corresponding to light beams having a plurality of types of wavelengths respectively corresponding to a plurality of types of the optical discs. An optical disc apparatus having an optical pickup that irradiates a desired position on a signal recording layer of an optical disc and a tracking drive unit that drives the optical pickup in a radial direction of the optical disc,
The above optical pickup
A lens holder provided with one or more objective lenses on its upper surface for condensing the light beam on the signal recording layer of the optical disc;
A base portion that supports the lens holder so as to be swingable in a tracking direction and a focusing direction, and
A tracking coil provided on a side surface of the lens holder for driving the lens holder in the tracking direction based on a predetermined tracking control current;
A focusing coil provided on a side surface of the lens holder for driving the lens holder in the focusing direction based on a predetermined focus control current;
A yoke fixed to the base portion, and holding a tracking magnet and a focusing magnet at positions corresponding to the tracking coil and the focusing coil, respectively.
The optical disk apparatus, wherein the tracking coil and the focusing coil are provided on the side surface of the lens holder in a state where the central axes of the tracking coil and the focusing coil are parallel to each other and separated by a predetermined distance, and the coil portions are partially overlapped.

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