JP2008065887A - Optical pickup - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup having high servo stability by suppressing unnecessary resonance such as rolling. <P>SOLUTION: This optical pickup includes a lens holder 2 having objective lenses 21 and 22 attached thereto, a support 3, elastic supporting members 6a to 6f for supporting the lens holder 2 on the support 3 so as to be movable, focus coils 12a to 12d at least a pair of which is disposed in a tracking direction T for generating driving force in a focusing direction F, tracking coils 11a and 11b for generating driving force in the tracking direction T, and a driving current supplying means for independently supplying driving currents to the focus coils 12a and 12d disposed on one side of the tracking direction and the focus coils 12b and 12c disposed on the other side. Driving currents decided according to the positions of the lens holder 2 in the focusing and tracking directions are supplied to the focus coils 12a and 12d and the focus coils 12b and 12c. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical pickup used for recording an information signal on an optical disc and reproducing the information signal recorded on the optical disc.

  Conventionally, optical discs such as CDs (Compact Discs) and DVDs (Digital Versatile Discs) have been used as recording media for information signals. Information signals are recorded on this type of optical discs, or information signals recorded on optical discs are reproduced. There is an optical disc device for performing the above-mentioned, and this optical disc device is provided with an optical pickup that is moved in the radial direction of the optical disc and irradiates the optical disc with a light beam.

  The optical pickup is provided with an objective lens driving device, and by this objective lens driving device, the focus coil is moved in the focus direction, which is the direction in which the objective lens held by the movable part is separated from or close to the signal recording surface of the optical disk. To adjust the focus by moving the objective lens by the tracking coil in the tracking direction which is substantially the radial direction of the optical disc.

  In addition, the objective lens driving device performs tilt adjustment by operating the tilt coil in a tilt direction that is a rotation direction around a tangential direction (jitter direction) that is a direction perpendicular to the focus direction and the tracking direction. The spot adjustment of the light beam applied to the optical disc via the optical disk is performed so that the spot of the light beam applied to the optical disc via the objective lens is condensed on the recording track of the optical disc.

  Further, the tilt direction can be adjusted by using the differential force by using two focus coils or tracking coils instead of using the tilt coil.

  For example, the objective lens driving device 201 of the optical pickup 200 includes focus coils 212a to 212d and a focus coil 212a to 212d for driving the objective lenses 204 and 205 provided in the movable portion 202, as shown in FIGS. Tracking coils 211 a and 211 b are provided on the front and back side surfaces of the movable portion 202 that is cantilevered by the support arm 206 from the support portion 203.

  In the optical pickup 200, the coils 211a, 211b, and 212a to 212d are supplied with a drive current determined by the DSP 220 shown in FIG. The DSP 220 includes a control calculation unit 222 for the focus coil and a control calculation unit 223 for the tracking coil. The control calculation unit 222 supplies a focus drive current to the focus coils 212 a to 212 d via the drive amplifier circuit 224 based on the focus error signal FE supplied via the matrix amplifier 221. The control operation unit 223 supplies a tracking drive current to the tracking coils 211 a and 211 b via the drive amplifier circuit 225 based on the tracking error signal TE supplied via the matrix amplifier 221. The matrix amplifier 221 detects various signals such as FE and TE based on the amount of light received by the optical detector 219 provided in the optical pickup and the reflected light on the signal recording surface of the optical disc 102.

  The optical pickup 200 includes a movable portion 202 and a tracking portion in a focus direction and a tracking direction by a magnetic field formed by magnets 213 and 214 provided to face the coils 211a, 211b, and 212a to 212d and a current supplied to the coils. The objective lens provided on this can be displaced. The movable portion 202 can be displaced in the tilt direction by a tilt coil and a magnet for the tilt coil (not shown).

  In addition, when the optical pickup 200 is of a so-called focus differential tilt method that enables tilt drive by the differential force of the focus coil, a drive current determined by the DSP 230 shown in FIG. 22 is supplied. The DSP 230 includes a control calculation unit 222 for the focus coil, a control calculation unit 223 for the tracking coil, and a tilt angle target value generation unit 231 that generates a tilt current as a tilt component for tilting the movable unit 202 in the tilt direction. And an adder 232 and a subtractor 233. The control calculation unit 222 supplies a focus drive current to the adder 232 and the subtractor 233 based on the focus error signal FE. The tilt angle target generation unit 231 generates a drive current for tilt for obtaining a driving force in a desired tilt direction based on a jitter amount and supplies the tilt drive current to the adder 232 and the subtracter 233. The adder 232 supplies the drive current If3 obtained by adding the drive current for focus and the drive current for tilt to the focus coils 212a and 212d via the drive amplifier circuit 234. The subtractor 233 supplies a drive current If4 obtained by subtracting the tilt drive current from the focus drive current to the focus coils 212b and 212c via the drive amplifier circuit 235.

  The optical pickup of the differential tilt method has a focus direction and a tracking direction depending on the magnetic field formed by the magnets 213 and 214 provided to face the coils 211a, 211b, and 212a to 212d and the current supplied to the coils. It is possible to displace the movable part 202 and the objective lens provided on the movable part 202. Further, in this optical pickup, currents obtained by adding or subtracting tilt components are supplied to focus coils 212a and 212d provided on one side in the tracking direction and focus coils 212b and 212c provided on the other side, respectively. Thus, the movable portion 202 can be displaced in the tilt direction.

  In such an optical pickup 200, the focus coils 212a to 212d and the tracking coils 211a and 211b are displaced due to the displacement of the focus coils 211a and 211b, the variation in the thickness, the disturbance of the winding, etc. If there is a difference, or the rotational axis shifts due to mass imbalance, that is, the center of the driving thrust of the focus coils 212a to 212d or the center of the driving thrust of the tracking coils 211a and 211b, and the center of gravity of the movable portion 202 If a rotational force (rolling torque) is generated due to a deviation from the above, the rolling Xro generated thereby adversely affects the transfer characteristics in the focus direction, tracking direction, and tilt direction, making the servo circuit unstable. There is a problem that It was.

  For example, in the optical pickup 200, as shown in FIGS. 19 and 20, when the center of thrust of the tracking coils 211a and 211b deviates from the center of gravity G of the movable portion 202, a desired focus direction F and tracking direction are obtained. In addition to the driving force in the T and tilt directions, a rotational force f3 around the axis in the tangential direction Tz (jitter direction) is generated. Further, when there is a deviation between the rotational center of the rotational force f3 and the mounting positions of the objective lenses 204 and 205, the rolling Xro due to the rotational force affects the tracking error signal, and the transfer characteristic in the tracking direction T is the rolling characteristic. As a result, the servo circuit becomes unstable. Furthermore, when the movable part 202 is displaced in the tracking direction T, for example, the strength of the magnetic field with respect to the left and right focus coils 212a to 212d changes, and the tangential direction Tz is caused by the difference in driving force between the left and right focus directions. There is a problem that a rotational force f4 in the direction around the axis is generated and the servo circuit is made unstable by the rolling Xro due to the rotational force f4.

  Here, the rolling Xro generated by the thrust of the tracking coils 211a and 211b will be specifically described with reference to FIG.

  If the point of action of the tracking coil drive thrust ft2 and the center of gravity G of the movable portion 202 are misaligned in the focus direction F, the rotational force f3 due to the drive thrust ft2 of the tracking coils 211a and 211b is caused by this misalignment. And rolling Xro occurs. In addition, even when the tracking coil drive thrust ft2 and the center of gravity G of the movable portion 202 are not displaced in the focus direction F, the movable portion 202 strokes in the focus direction F and the tracking direction T, thereby opposing magnets 213. , 214 changes the relationship between the tracking coils 211a, 212b and the position of the operating point of the driving thrust ft2, and the position of the operating point of the driving thrust ft2 and the center of gravity G in the focus direction F. This causes a deviation, and thereby rolling Xro occurs.

  Next, rolling Xro generated by the thrust of the focus coils 212a to 212d will be specifically described with reference to FIG. Hereinafter, a focus coil 212a (hereinafter also referred to as “right focus coil 212a”) provided on one end side in the tracking direction on the distal end side of the movable portion 202, and a focus coil 212b (hereinafter referred to as “right focus coil 212a”) provided on the other end side. The focus coil 212c is the same as the left focus coil 212b, and the focus coil 212d is the same as the right focus coil 212a. To do.

  As shown in FIG. 20, since the focus coils 212a and 212b arranged side by side in the tracking direction T are arranged so as not to cause a positional deviation with respect to the center of gravity, the positional deviation occurs with respect to the center of gravity. It is relatively easy to prevent. However, in such a configuration, when the movable portion 202 is stroked in the tracking direction T, the relationship between the magnetic flux formed by the opposing magnet 213 and the focus coils 212a and 212b provided on the left and right changes. That is, a large magnetic field is formed in the right focus coil 212a that has moved to the center side of the magnet 213 when the movable portion 202 is stroked in one of the focus directions F, and the driving thrust ff7 by the coil 212a increases, and the magnet 213 A small magnetic field is formed in the focus coil 212b that has moved to the end side, and the driving thrust ff8 by the coil 212b is reduced. As a result, a difference occurs in the driving force, and a rotational force is generated due to the difference in the driving force, and rolling Xro is generated.

  This means that the focus coils 212a and 212d and the focus coils 212b and 212c in FIG. 18 can be driven separately, and the focus differential tilt is performed by adjusting the thrust of the two focus coils, respectively. The same applies to the optical pickup of the system. That is, when the movable portion 202 strokes in the tracking direction T, the thrust generated in the focus coils 21 and 22 changes, so that a thrust shift other than the tilt adjustment that is originally desired occurs, resulting in the suspension reaction force and the inertia of the objective lens driving device. It appears as rolling Xro having a resonance frequency determined depending on the weight.

JP 2001-134963 A

  An object of the present invention is to generate rolling in the direction around the axis in the tangential direction perpendicular to the tracking direction and the focus by the driving force of the focus coil or the tracking coil even when the lens holder is displaced in the focus direction and / or the tracking direction. It is an object of the present invention to provide an optical pickup having high servo stability while suppressing unnecessary resonance due to oscillation of the like.

  In order to achieve this object, an optical pickup according to the present invention is provided with an objective lens for condensing a light beam on a signal recording surface of a rotationally driven optical disc, and a focus direction parallel to the optical axis of the objective lens; A lens holder that is moved in a tracking direction orthogonal to the optical axis direction of the objective lens, and a support that is disposed with a gap in the focus direction and a tangential direction orthogonal to the tracking direction with respect to the lens holder. An elastic support member that connects the body, the lens holder, and the support, and supports the lens holder movably in the focus direction and the tracking direction with respect to the support, and the lens holder. , At least a pair provided side by side in the tracking direction for generating a driving force in the focus direction A focus coil, a tracking coil that is provided in the lens holder and generates a driving force in the tracking direction, at least a pair of magnets that are arranged to face the focus coil and the tracking coil, and one of the tracking directions Drive current supply means for independently supplying a drive current to the focus coil provided on the other side in the tracking direction and the focus coil provided on the other side in the tracking direction, provided on the one side. The focus coil and the focus coil provided on the other side are supplied with drive currents determined according to the positions of the lens holder in the focus direction and the tracking direction, respectively.

  In the optical pickup according to the present invention, an objective lens for condensing a light beam is attached to the signal recording surface of a rotationally driven optical disc, and the focus direction parallel to the optical axis of the objective lens and the light of the objective lens A lens holder that is moved in a tracking direction orthogonal to the axial direction; a support that is disposed with a gap in the tangential direction orthogonal to the focus direction and the tracking direction relative to the lens holder; and the lens An elastic support member that connects the holder and the support body, and supports the lens holder movably in the focus direction and the tracking direction with respect to the support body; and provided in the lens holder, in the focus direction. A focus coil for generating a driving force and the tracking provided on the lens holder A tracking coil that generates a driving force in the direction, at least a pair of magnets disposed opposite to the focus coil and the tracking coil, and the lens holder in a tilt direction that tilts about the axis in the tangential direction. A tilt coil that generates a force and a tilt magnet disposed opposite to the tilt coil, and the tilt coil is driven according to the position of the lens holder in the focus direction and the tracking direction. Current is supplied.

  The present invention has at least a pair of focus coils provided side by side in the tracking direction, and the focus of the lens holder is provided on the focus coil provided on one side of the tracking direction and the focus coil provided on the other side. Oscillating motion such as rolling that occurs around the axis in the tangential direction generated by the driving force of the focus coil and tracking coil by independently supplying a drive current determined according to the position in the direction and tracking direction Unnecessary resonance due to can be suppressed and high servo stability can be obtained.

  The present invention also includes a tilt coil that generates a driving force for driving the lens holder in a tilt direction that tilts the lens holder in the direction around the axis in the tangential direction. The tilt coil includes positions of the lens holder in the focus direction and the tracking direction. By independently supplying the drive current determined according to the driving force, unnecessary resonance due to the swinging operation such as rolling that occurs around the axis in the tangential direction caused by the driving thrust of the focus coil and the tracking coil is suppressed. High servo stability can be obtained.

  Hereinafter, an optical disk apparatus using an optical pickup to which the present invention is applied will be described with reference to the drawings.

  As shown in FIG. 1, an optical disc apparatus 101 to which the present invention is applied has a spindle as a driving means for rotationally driving an optical disc 102 as an optical recording medium such as a CD, a DVD, a CD-R, a DVD ± R, and a DVD-RAM. A motor 103, an optical pickup 1, and a feed motor 105 as drive means for moving the optical pickup 1 in the radial direction thereof are provided. Here, the spindle motor 103 is controlled by the system controller 107 and the control circuit unit 109 so as to be driven at a predetermined rotational speed.

  The signal modulation / demodulation unit and ECC block 108 modulates and demodulates a signal output from the signal processing unit 120 and adds an ECC (error correction code). The optical pickup 1 irradiates the signal recording surface of the optical disc 102 rotating according to instructions from the system controller 107 and the control circuit unit 109 with a light beam. Information signals are recorded on the optical disc 102 by such light beam irradiation, and the information signals recorded on the optical disc are reproduced.

  The optical pickup 1 detects various light beams as will be described later based on the reflected light beam reflected from the signal recording surface of the optical disc 102 and sends detection signals obtained from the respective light beams to the signal processing unit 120. It is configured to supply.

  The signal processing unit 120 generates various servo signals based on detection signals obtained by detecting each light beam, that is, a focus error signal and a tracking error signal, and is an information signal recorded on the optical disc. An RF signal is generated. Further, predetermined processing such as demodulation and error correction processing based on these signals is performed by the control circuit unit 109, the signal modulation / demodulation unit, the ECC block 108, and the like according to the type of recording medium to be reproduced.

  Here, if the recording signal demodulated by the signal modulation / demodulation unit and the ECC block 108 is for data storage of a computer, for example, it is sent to the external computer 130 or the like via the interface 111. Accordingly, the external computer 130 and the like are configured to receive a signal recorded on the optical disc 102 as a reproduction signal.

  In addition, if the recording signal demodulated by the signal modulation / demodulation unit and the ECC block 108 is for audio / visual use, the digital / analog conversion is performed by the D / A conversion unit of the D / A and A / D converter 112 and the audio / visual conversion is performed. It is supplied to the processing unit 113. Audio / video signal processing is performed by the audio / visual processing unit 113 and transmitted to an external imaging / projection device via the audio / visual signal input / output unit 114.

  A feed motor 105 is connected to the optical pickup 1. The optical pickup 1 is fed in the radial direction of the optical disc 102 by the rotation of the feed motor 105 and moved to a predetermined recording track on the optical disc 102. The control of the spindle motor 103, the control of the feed motor 105, and the control of the actuator that moves and displaces the objective lens of the optical pickup 1 in the focus direction that is the optical axis direction and the tracking direction orthogonal to the optical axis direction are respectively control circuits. This is performed by the unit 109.

  That is, the control circuit unit 109 controls the spindle motor 103 and controls the actuator based on the focus error signal and the tracking error signal.

  The control circuit unit 109 is driven to supply tracking coils 11a and 11b and focus coils 12a to 12d, which will be described later, based on a focus error signal, a tracking error signal, an RF signal, and the like input from the signal processing unit 120. Each of the signals (drive currents) is generated.

  The laser control unit 121 controls a laser light source in the optical pickup 1.

  Here, the focus direction F refers to the optical axis direction of the objective lenses 21 and 22 (see FIG. 3) of the optical pickup 1, and the tangential direction Tz is a direction orthogonal to the focus direction F and is the optical disc apparatus 101. The tracking direction T is a direction orthogonal to the focus direction F and the tangential Tz direction. In addition, a difference angle in which an angle formed by the optical axis of the objective lenses 21 and 22 and a virtual line passing through the optical axis and extending in the radial direction of the optical disc 102 is shifted from 90 degrees is a tilt angle in the radial direction. That's it.

  In addition, the optical disc apparatus 101 is provided with a tilt detection unit that detects the tilt of the optical disc 102 mounted on the spindle motor 103 based on the jitter amount or the like. A detection signal detected by the inclination detection unit is supplied to the control circuit unit 109. The control circuit unit 109 outputs a tilt angle control signal based on the tilt detection signal and supplies the tilt angle control signal to the driving unit 5 described later. The drive means 5 adjusts the tilt angle by driving and displacing the objective lenses 21 and 22 with a drive current according to the tilt angle control signal.

  Next, the optical pickup 1 to which the present invention is applied will be described in detail.

  The optical pickup 1 is an optical disc that records and / or reproduces information signals with respect to a plurality of types of optical discs 102 on which information signals are recorded or reproduced by selectively using a plurality of types of light beams having different wavelengths. Specifically, a first optical disk on which an information signal is recorded or reproduced using a light beam having a wavelength of about 400 to 410 nm and a light beam having a wavelength of about 650 to 660 nm are used. Information signal recording and / or recording with respect to the second optical disk on which information signals are recorded or reproduced and the third optical disk on which information signals are recorded or reproduced using a light beam with a wavelength of about 760 to 800 nm A description will be given assuming that reproduction is performed.

  In the following description, the optical pickup 1 is described as performing recording and / or reproduction of information signals with respect to three different types of optical discs. However, the present invention is not limited to this, and a plurality of different types or one type of optical discs are used. The information signal may be recorded and / or reproduced.

  An optical pickup 1 to which the present invention is applied includes a semiconductor laser as a light source that emits a plurality of types of light beams having different wavelengths, and a light detection element that detects a reflected light beam reflected from the signal recording surface of the optical disk 102. And an optical system that guides the light beam from the semiconductor laser to the optical disc 102 and guides the light beam reflected by the optical disc 102 to the light detection element.

  Further, as shown in FIG. 2, the optical pickup 1 includes the mounting base 9 in which the above-described optical system is disposed and is movable in the radial direction of the optical disk 102 within the housing of the optical disk apparatus 101, and the mounting base. And an objective lens driving device 7 disposed on the table 9. The mounting base 9 has bearing portions 10a and 10b at both ends thereof, and the bearing portions 10a and 10b are slidably supported by guide shafts (not shown). A guide shaft (not shown) provided on the attachment base 9 is slidably supported. When a rack member (not shown) provided on the mounting base 9 is screwed to the lead screw and the lead screw is rotated by the feed motor, the rack member is sent in a direction corresponding to the rotation direction of the lead screw, and the optical pickup 1 is moved in the radial direction of the optical disk 102.

  The optical pickup 1 includes a lens holder 2 that supports a plurality of objective lenses 21 and 22 that collect a light beam emitted from a light source and irradiate the optical disk as shown in FIGS. To a tangential direction Tz and a support 3 attached to an attachment base. The first and second objective lenses 21 and 22 constitute a part of the optical system of the optical pickup 1. Here, the lens holder 2 and the support 3 together with the elastic support member 4, the drive means 5 and the support arms 6 a to 6 f, which will be described later, the objective lenses 21 and 22 held by the lens holder 2 as a movable part are used as optical signal signals. An objective lens driving device 7 that enables focus adjustment by operating in the focus direction with respect to the recording surface, tracking adjustment by operating in the tracking direction, and tilt adjustment by operating in the tilt direction. The light beam is condensed on a predetermined recording track of the optical disk via the objective lens, and the condensed spot can be adjusted.

  Here, the first objective lens 21 is used for condensing, for example, a light beam having a wavelength of 650 to 660 nm and a light beam having a wavelength of 760 to 800 nm on the second or third optical disk, The second objective lens 22 is used for condensing a light beam having a wavelength of 400 to 410 nm on the first optical disk. The first and second objective lenses 21 and 22 are arranged in parallel in the tangential direction Tz. Here, the first objective lens 21 is provided on the support body 3 side, which is a fixed portion side of support arms 6a to 6f described later, and the second objective lens 22 is provided on the distal end side of the lens holder 2. Is located.

  The optical pickup 1 is configured to include a plurality of objective lenses 21 and 22 that are arranged side by side in the tangential direction Tz. However, the number and arrangement of the objective lenses are not limited thereto, and for example, a plurality of objective lenses may be provided. The objective lens may be configured to be arranged in the radial direction, or may be configured to include one objective lens.

  As shown in FIGS. 3 and 4, the lens holder 2 is provided so as to surround the outer peripheral surfaces of the first and second objective lenses 21 and 22, and the first and second objective lenses 21 and 22 are used as objectives. The lens is supported so as to be movable in a focus direction F parallel to the optical axis of the lens and a tracking direction T orthogonal to the optical axis.

  As shown in FIGS. 3, 4, and 5, the tracking direction T, which is a substantially radial direction of the optical disc 102, is disposed on the side surface facing the tangential direction Tz orthogonal to the focus direction F and the tracking direction T of the lens holder 2. First and second tracking coils 11a and 11b that generate a driving force, and first to fourth focus coils 12a and 12b that generate a driving force in a focus direction F that is a direction approaching and separating from the optical disc 102. 12c and 12d are attached. Here, the first tracking coil 11a and the first and second focus coils 12a and 12b are provided on the side surface on the distal end side, which is one of the side surfaces of the lens holder 2, and the second tracking coil 11b and the second tracking coil 11b. The third and fourth focus coils 12 c and 12 d are provided on the side surface on the base end side that is the other side surface of the lens holder 2. The first and second focus coils 12a and 12b are arranged in a pair along the tracking direction, and the third and fourth focus coils 12c and 12d are arranged in a pair along the tracking direction. The first and fourth focus coils 12a and 12d are arranged on one side in the tracking direction T, and the second and third focus coils 12b and 12c are arranged on the other side in the tracking direction T. Yes.

  On both side surfaces spaced apart in the tracking direction T of the lens holder 2, there are provided support arms 6a, 6b, 6c and arm support portions 24 for supporting the support arms 6d, 6e, 6f, which are provided at intervals in the focus direction F, respectively. It has been. The support arms 6 a to 6 f function as elastic support members that support the lens holder 2 so as to be movable in the focus direction and the tracking direction with respect to the support 3.

  As shown in FIG. 3, a yoke 18 is disposed between the lens holder 2 and a mounting base (not shown). The yoke 18 is attached to the base 8 and fixed to the attachment base. An opening for transmitting a light beam incident on the first and second objective lenses 21 and 22 is provided at a substantially central portion of the yoke 18.

  On both sides of the yoke 18 in the tangential direction Tz, as shown in FIG. 3, a pair of yoke pieces 18a and 18b are formed so as to face each other with the first and second objective lenses 21 and 22 therebetween. . First and second magnets 13 and 14 are attached to opposing surfaces of the yoke pieces 18a and 18b. Here, the first magnet 13 is disposed on the movable portion side, that is, the tip end side of the lens holder 2, and the second magnet 14 is disposed on the fixed portion side, that is, the support body 3 side.

  As shown in FIG. 3 and FIG. 6A, the first magnet 13 is disposed to face the lens holder 2 in the tangential direction Tz, and the magnetization direction in each region is the tangential direction Tz. It has 1st thru | or 4th division area 13a, 13b, 13c, 13d magnetized toward any one.

  Here, the first divided region 13a is formed in a substantially rectangular shape, and is magnetized so that the surface on the lens holder 2 side has an N pole. The second divided region 13b has a portion adjacent to the focus direction F of the first divided region 13a and a portion adjacent to the tracking direction T, and one of the focus directions of the first divided region 13a and the tracking direction. And is magnetized in the direction opposite to that of the first divided region 13a, that is, the surface on the lens holder 2 side is magnetized so as to be an S pole. The third and fourth divided regions 13c and 13d are magnetized so as to be symmetrical with the first and second divided regions 13a and 13b with respect to the focus direction F, respectively.

  The S pole and the N pole of the first to fourth divided regions of the first magnet 13 described above are not limited to this, and may be reversed, for example.

  As shown in FIGS. 3 and 6B, the second magnet 14 is disposed on the opposite side of the first magnet 13 with respect to the lens holder 2 so as to face the tangential direction Tz. 13 have fifth to eighth divided areas 14 a, 14 b, 14 c, 14 d which are divided areas having the same shape as 13.

  The S pole and N pole of the fifth to eighth divided regions of the second magnet 14 described above may be reversed.

  As described above, the first and second magnets 13 and 14 are opposed to the tracking coils 11a and 11b and the focus coils 12a to 12d attached to the opposite side surfaces of the lens holder 2, respectively. A predetermined magnetic field is applied to each of the coils arranged.

  As shown in FIGS. 6A and 6B, the tracking coils 11a and 11b are portions adjacent to the tracking direction T of the second and fourth divided regions 13b and 13d of the first magnet 13, respectively. And the magnetic field formed by these divided areas, and the coils, which are arranged at positions facing the portions of the second magnet 14 adjacent to the tracking direction T of the sixth and eighth divided areas 14b and 14d. A driving force is generated in the tracking direction T depending on the direction and magnitude of the current flowing through the.

  As shown in FIGS. 6A and 6B, the focus coils 12a to 12d are portions adjacent to the focus direction F of the first and second divided regions 13a and 13b of the first magnet 13, respectively. A portion of the first magnet 13 adjacent to the focus direction F of the third and fourth divided regions 13c and 13d, a fifth and sixth divided regions 14a and 14b of the second magnet 14, and a second The magnet 14 is arranged at a position facing the seventh and eighth divided regions 14c and 14d, and the focus is determined by the magnetic field formed by these divided regions and the direction and magnitude of the current flowing through each coil. A driving force is generated in the direction F.

  As described above, the tracking magnet 11a and the focus coils 12a and 12b are opposed to the first magnet 13, and the tracking coil 11b and the focus coils 12c and 12d are opposed to the second magnet 14 so that each tracking coil 11a and When the tracking drive current is supplied to 11b, the lens holder 2 is driven and displaced in the tracking direction T by the interaction between the drive current supplied to each tracking coil and the magnetic field from each magnet 13 and 14, and each focus. When the focus drive current is supplied to the coils 12a to 12d, the lens holder 2 is driven and displaced in the focus direction F by the interaction between the drive current supplied to the focus coil and the magnetic fields from the magnets 13 and 14.

  As a result, the first and second objective lenses 21 and 22 supported by the lens holder 2 are driven and displaced in the focus direction F or the tracking direction T, and the optical disc is passed through the first and second objective lenses 21 and 22. Tracking control is performed so that the light beam irradiated onto the optical disc 102 is controlled so as to be focused on the signal recording surface of the optical disc 102, and the optical beam is controlled so as to follow the recording track formed on the optical disc 102. Is done.

  As shown in FIGS. 3 and 4, the support 3 has a length along the tracking direction T with respect to the lens holder 2 and a height along the focus direction F.

  Arm support portions 31 that support the support arms 6a, 6b, and 6c and the support arms 6d, 6e, and 6f are provided on both side surfaces of the support 3 that are spaced apart in the tracking direction T, with an interval in the focus direction F, respectively. Yes. A printed wiring board (not shown) is attached to the back side of the support 3. The printed circuit board is supplied with a driving current for focusing and a driving current for tracking from the control circuit unit 109.

  The arm support portions 24 on both sides in the tracking direction T of the lens holder 2 and the arm support portions 31 on both sides in the tracking direction T of the support body 3 are connected by one and the other support arms 6a to 6f, respectively. . As shown in FIGS. 3 to 5, the one and the other support arms 6 a to 6 f are provided in parallel to each other at an interval in the focus direction T, and the lens holder 2 is placed in the focus direction F with respect to the support 3. It is supported so as to be movable in the tracking direction T. Each of the support arms 6a to 6f is made of a linear member having conductivity and elasticity.

  In the optical pickup 1, each of these support arms 6a to 6f functions as a drive current supply unit that supplies a drive current determined by the DSP 60 described later to the focus coils 12a to 12d and the tracking coils 11a and 11b. Here, each of the support arms 6a to 6f serving as the drive current supply means has focus coils 12a and 12d (hereinafter referred to as “right focus coil 12a, 12d ") and focus coils 12b and 12c (hereinafter also referred to as" left focus coils 12b and 12c ") provided on the left side which is the other side of the tracking direction F. A driving current is supplied, and a tracking driving current is supplied to the tracking coils 11a and 11b.

  That is, the support arm 6a, 6d has its end on the lens holder 2 side connected to a connection terminal provided on the focus coils 12a, 12d by soldering or the like, and the end on the support 3 side has a printed wiring board. Are connected to the conductive pattern provided on the substrate. As a result, the drive current for focus from the control circuit unit 109 is supplied to the focus coils 12a and 12d via the support arms 6a and 6d.

  The support arms 6b and 6e have their lens holder 2 side ends connected to connection terminals provided on the focus coils 12b and 12c by soldering, and the support 3 side ends are printed wiring boards. Are connected to the conductive pattern provided on the substrate. As a result, the drive current for focus from the control circuit unit 109 is supplied to the focus coils 12b and 12c via the support arms 6b and 6e.

  Further, the support arms 6c and 6f have their end portions on the lens holder 2 side connected to connection terminals provided on the tracking coils 11a and 11b by soldering or the like, and the end portions on the support body 3 side are printed circuit boards. Are connected to the conductive pattern provided on the substrate. Thus, the tracking drive current from the control circuit unit 109 is supplied to the tracking coils 11a and 11b via the support arms 6c and 6f.

  Here, the six support arms 6a to 6f are provided so as to function as an elastic support member that movably supports the lens holder 2 and function as drive current supply means. However, the number of support arms is as follows. The present invention is not limited to this, and other drive current supply means such as a power supply line may be provided.

  The right focus coils 12a and 12d provided on one side in the tracking direction T and the left focus coils 12b and 12c provided on the other side in the tracking direction T are respectively in the focus direction F of the lens holder 2. A driving current determined according to the position in the tracking direction T is supplied.

  Here, the DSP 60 provided in the control circuit unit 109 for determining the drive current supplied to the right focus coils 12a and 12d and the left focus coils 12b and 12c will be described with reference to FIG.

  The DSP 60 includes a first control calculation unit 63 that calculates the focus drive current Fd based on the focus error signal FE supplied via the matrix amplifier 61 provided in the signal processing unit 120, and the matrix amplifier 61. And a second control calculation unit 64 that calculates the tracking drive current Td based on the supplied tracking error signal TE. The matrix amplifier 61 uses a focus error signal FE, a tracking error signal TE, and the like based on the amount of light received by the optical detector 23 provided in the optical pickup 1 from the reflected light beam reflected from the signal recording surface of the optical disk 102. The various detection signals are detected.

  The DSP 60 also includes a focus position calculation unit 65 that calculates the focus position z of the lens holder 2 from the focus drive current Fd calculated by the first control calculation unit 63 and a tracking drive current calculated by the second control calculation unit 64. Based on the tracking position calculation unit 66 that calculates the tracking position y of the lens holder 2 from Td, and the focus position and tracking position of the lens holder 2 calculated by the focus position calculation unit 65 and the tracking position calculation unit 66, the right focus A focus differential coefficient calculator 67 for determining a coefficient K (z, y) for determining a drive current to be supplied to the coils 12a and 12d and the left focus coils 12b and 12c, a focus position calculator 65, and a tracking position calculator 4 of the lens holder 2 calculated by the unit 66. A focus tracking conversion coefficient calculation unit 68 that determines a coefficient At (z, y) for determining a drive current to be supplied to the right focus coils 12a and 12d and the left focus coils 12b and 12c based on the focus position and the tracking position. And have.

  Here, z indicates the position of the lens holder 2 in the focus direction F, y indicates the position of the lens holder 2 in the tracking direction T, and K (z, y) indicates the lens. The differential coefficient for determining the drive current for focus supplied to the right and left focus coils when the holder 2 is in the position of z, y is shown. At (z, y) is the lens holder 2. 4 shows conversion coefficients for determining focus drive currents supplied to the right and left focus coils when z is at the positions of z and y.

  The coefficient K (z, y) determined by the focus operation coefficient calculator 67 applies a drive current to the right focus coils 12a and 12d and the left focus coils 12b and 12c by changing the position of the lens holder 2. It is set so as to cancel the rolling Xro caused by the difference in driving thrust of the right and left focus coils due to the change in the magnetic field effect by the magnets 13 and 14.

  Further, the coefficient At (z, y) determined by the focus tracking conversion coefficient calculation unit 68 applies a driving current, and the position of the lens holder 2 changes to change the center of the driving thrust of the tracking coil and the lens holder 2. The rolling Xro generated due to the deviation from the center of gravity is set to be offset by providing a difference in the drive current supplied to the right focus coils 12a and 12d and the left focus coils 12b and 12c.

  The focus operation coefficient calculation unit 67 calculates the coefficient K (z, y) and, based on the coefficient K (z, y) and the supplied focus drive current Fd, the focus on one side and the other side. Two types of drive currents (K (z, y) × Fd, {1−K (z, y)} × Fd) for the coil are generated.

  The focus tracking conversion coefficient calculation unit 68 calculates the coefficient At (z, y) and, based on the coefficient At (z, y) and the supplied tracking drive current Td, the one side and the other side. A drive current (At (z, y) × Td) for determining the drive current for the focus coil is generated.

  The DSP 60 also includes an adder 69 that adds the drive current determined by the focus differential coefficient calculation unit 67 and the drive current determined by the focus tracking conversion coefficient calculation unit 68, and a focus differential coefficient calculation unit 67. A subtractor 70 for subtracting the drive current determined by the focus tracking conversion coefficient calculation unit 68 from the determined drive current.

The adder 69 is based on the drive current determined by the focus differential coefficient calculator 67 and the drive current determined by the focus tracking conversion coefficient calculator 68, and the tracking direction T determined by the following equation (1). Is supplied to the right focus coils 12a and 12d via a drive amplifier circuit 73 to be described later. On the other hand, the subtractor 70 is based on the drive current determined by the focus differential coefficient calculation unit and the drive current determined by the focus tracking conversion coefficient calculation unit 68, and the tracking direction determined by the following equation (2). The drive current If2 for the focus coil on the other side of T is supplied to the left focus coils 12b and 12c via a drive amplifier circuit 72 described later.
If1 = K (z, y) × Fd + At (z, y) × Td (1)
If2 = {1-K (z, y)} * Fd-At (z, y) * Td (2)
The coefficient K (z, y) determined by the focus operation coefficient calculator 67 and the coefficient At (z, y) determined by the focus tracking conversion coefficient calculator 68 are the focus position z and tracking position of the lens holder 2. It is determined based on y. Specifically, the center position and the magnitude of the driving thrust of each coil are calculated in advance from the position of the center of gravity of the lens holder 2 and the positions of the coils 12a to 12d and the magnets 13 and 14 by calculation such as simulation for each position. The selected one is selected by the focus position and tracking position (z, y). The coefficient K (z, y) is set in the range of about 0.4 to 0.6.

  Here, the relationship between the coefficient K (z, y) and the rolling Xro will be described using specific numerical values. Here, in FIG. 8, a plurality of objective lenses are arranged side by side in a radial direction that is more effective. The relationship between the coefficient K (z, y) in the example of the optical pickup 1A shown and the rolling Xro will be described with reference to FIG.

  First, the optical pickup 1A shown in FIG. 8 will be described. In the following description, the optical pickup 1A has the same configuration as the optical pickup 1 shown in FIGS. 2 and 3 except for the objective lens. About a part, a common code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 8, the optical pickup 1 </ b> A supports a lens holder 2 that supports a plurality of objective lenses 21 </ b> A and 22 </ b> A that collects a light beam emitted from a light source and irradiates the optical disk, and supports the same as the optical pickup 1. It has the body 3, the elastic support member 4, the drive means 5, and the support arms 6a-6f. The first and second objective lenses 21A and 22A constitute a part of the optical system of the optical pickup 1A.

  Here, the first objective lens 21A is used, for example, to focus a light beam having a wavelength of 650 to 660 nm and a light beam having a wavelength of 760 to 800 nm on the second or third optical disk, The second objective lens 22A is used for condensing a light beam having a wavelength of 400 to 410 nm on the first optical disk. The first and second objective lenses 21A and 22A are arranged in parallel in the radial direction, that is, the tracking direction T. Here, the first objective lens 21A is located at a position facing the outer peripheral side of the optical disc. The second objective lens 22A is disposed at a position facing the inner peripheral side of the optical disc.

  Also in the optical pickup 1A configured as described above, the drive current determined by the DSP is supplied to each coil as in the optical pickup 1 described above.

  FIG. 9 is a graph showing the relationship between the rolling Xro phase and the balance of the driving forces of the left and right coils determined by the coefficient K (z, y) in the optical pickup 1A as described above. The horizontal axis in FIG. 9 is supplied with the drive current calculated by the equation (2) with respect to the gain of the focus coils 12a and 12d to which the drive current calculated by the equation (1) is supplied. The gain ratio ΔGain of the focus coils 12b and 12c is shown, the vertical axis shows the rotation around the rolling phase, the solid line L01 shows the change around the rolling phase accompanying the change in the gain ratio in the first objective lens 21A, and the solid line L02 indicates a change around the rolling phase accompanying a change in the gain ratio in the second objective lens 22 A. As shown in Fig. 9, the rolling Xro phase control with the left and right gain ratio ΔGain of ± 2 dB and ± 40 deg. The gain ratio ΔGain is calculated by 20 times the common logarithm of the value calculated by (1−K) / K. ΔGain = + 2 dB is when the coefficient K (z, y) = 0.443, and ΔGain = −2 dB is when the coefficient (z, y) = 0.557. Further, when the coefficient K (z, y) = 0.4 and 0.6, ΔGain = 3.5 and −3.5 dB, respectively. Xro can be controlled, that is, the rolling Xr can be reduced, where the count K (z, y) is calculated using specific numerical values of the optical pickup 1A in which the objective lenses 21A and 22A are arranged in the radial direction. And the relationship with the rolling Xro, the optical pickup 1 in which the objective lenses 21 and 22 are arranged side by side in the tangential direction described above, or one objective lens that is not described here, is provided. For even an optical pickup or the like, by setting the coefficient K to a predetermined range, and controls the rolling XRO, the effect of reducing to obtain substantially the same manner.

  In this example, the optimal coefficient corresponding to the position of the lens holder 2 is calculated, but the coefficient calculated by experiment may be used.

  When the coefficient K (z, y) is experimentally obtained, the transfer function from the focus drive current Fd to the focus error signal or the displacement of the lens holder 2 in the tracking direction T is measured. When measuring the displacement of the lens holder 2 in the tracking direction T, the displacement may be calculated, for example, using an integrated value of a laser Doppler device or using a measuring means such as a displacement sensor. Adjustment can be made by looking at the gain and phase of the Xro resonance frequency of this measurement result.

  As shown in FIG. 10, in this transfer function, when Xro cannot be canceled, the gain and phase are disturbed as indicated by broken lines L11 and L12 or alternate long and short dash lines L21 and L22 in FIG. Here, when K is changed, the phase of the rolling Xro changes from plus (+) to minus (-) or vice versa, so the K (z, y) value is changed while looking around the rolling Xro phase. What is necessary is just to set to an appropriate value and to have a characteristic as shown by the solid lines L31 and L32. This K changes according to the magnetized state of the magnet, the focus stroke amount (z), and the tracking stroke amount (y). Therefore, it is desirable to calculate K (z, y) for each of the focus stroke position z and the tracking stroke position y.

  Next, when the coefficient At (z, y) is experimentally obtained, the transfer function from the tracking drive current Td to the tracking error signal or the displacement of the lens holder 2 in the tracking direction T is measured. Also in this case, similarly to the above-described adjustment of K, when Xro cannot be canceled, the characteristics are as indicated by broken lines L11 and L12 or one-dot chain lines L21 and L22 in FIG. Therefore, the At (z, y) value may be set to an appropriate value so that the characteristics shown by the solid lines L31 and L32 are obtained. Further, this At changes according to the magnetized state of the magnet, the focus stroke amount (z), and the tracking stroke amount (y). Therefore, it is desirable to calculate as At (z, y) in each case of the focus stroke position z and the tracking stroke position y.

  Here, when generating the focus position y and the tracking position z, a constant position independent of the disk rotation is calculated by using a DC pass filter which is the focus position calculation unit 65 and the tracking position calculation unit 66. However, if the band is extended to the rotation frequency, which is the main component of fluctuations caused by the rotation of the disk, if possible due to the calculation speed, more accurate control can be achieved.

  Here, as the focus position y and the tracking position z, a DC component obtained by averaging fluctuations due to the disk rotation, and an eccentricity caused by the spindle motor 103 and the optical disk 102 itself, and an AC component caused by surface run-out exist. . Although a constant position independent of the disk rotation is calculated by using a DC pass filter which is the focus position calculation unit 65 and the tracking position calculation unit 66, the disk rotation is possible if possible due to the calculation speed. If the band is extended to the rotation frequency, which is the main component of the fluctuations generated by, the correction range is extended to the slope generated for this AC component, and control with higher accuracy becomes possible.

  Further, the control circuit unit 109 is provided with first to third drive amplifier circuits 71, 72, and 73 that amplify each drive current determined and adjusted by the DSP 60 and supply the drive current to each coil. The first drive amplifier circuit 71 amplifies the tracking drive current Td supplied from the second control operation unit 64 and supplies the amplified tracking drive current Td to the tracking coils 11a and 11b. The second amplifying circuit 72 amplifies the drive current If2 obtained by the subtractor 70 based on the drive current calculated by the focus differential coefficient calculation unit 67 and the focus tracking conversion coefficient calculation unit 68, and the left focus coil 12b, 12c. The third amplifying circuit 73 amplifies the drive current If1 obtained by the adder 69 based on the drive current calculated by the focus differential coefficient calculation unit 67 and the focus tracking conversion coefficient calculation unit 69, and the right focus coil 12a, 12d.

  As described above, the drive current determined according to the position of the lens holder 2 is independently supplied to the right focus coils 12a and 12d and the left focus coils 12b and 12c. The position of the rolling holder Xro generated by the difference between the driving force of the right focus coils 12a and 12d and the driving force of the left focus coils 12b and 12c due to the change in the influence of the magnetic field on each focus coil and the position of the lens holder 2 By changing, it becomes possible to suppress the rolling Xro that occurs when the center of the driving force of the tracking coils 11a and 11b and the position of the center of gravity of the lens holder 2 shift.

  In the objective lens driving device 7 of the optical pickup 1, the lens holder 2 to which the first and second objective lenses 21 and 22 are attached has the first and second objectives in the extending direction of the support arms 6 a to 6 f. Both sides of the intermediate portion between the optical axes of the lenses 21 and 22 are supported by 6a to 6f. That is, the lens holder 2 is configured to fix at least the tip ends of the support arms 6a to 6f to the arm support portions 24 provided on both sides of the intermediate portion between the optical axes of the first and second objective lenses 21 and 22. It is supported so as to be displaceable in the biaxial direction of the focus direction F and the tracking direction T.

  It should be noted that the positions supported by the tip portions of the support arms 6a to 6f of the lens holder 2 are preferably located on both sides of the center of gravity of the lens holder 2 to which the tracking coils 11a and 11b and the focus coils 12a to 12d are attached. By supporting such a position, the first and second objective lenses 21 and 22 can be stably displaced in the focus direction F and the tracking direction T without causing twist or the like.

  The optical pickup 1 includes an elastic support member 4 that supports the lens holder 2 via a pair of left and right support arms 6 a to 6 f so as to be tiltable with respect to the base 8, and an elastic support member 4. Drive means 5 for tilting the support body 3 supported so as to be tiltable in a tilt direction, which is a direction around an axis about the tangential direction Tz, according to the tilt of the optical disk 102.

  The elastic support member 4 is a pair of plate-like leg pieces 41 provided so as to be inclined so as to increase the distance from one end side supporting the support body 3 toward the other end side fixed to the base 8. , 41, and the leg pieces 41, 41 can tilt the support 3 with respect to the base 8 in a tilt direction (so-called radial tilt direction) that is a direction around an axis about the tangential direction Tz. It is something to support.

  In the elastic support member 4, one end side of the pair of leg pieces 41, 41 is attached to the support body 3 via a support attachment member 44, and the other end side is attached to the base 8 via a base attachment member 45. The elastic support member 4 is thus fixed to the support 3 and the base 8 by the support mounting member 44 and the base mounting member 45, and supports the support 3 so as to be tiltable with respect to the base 8. Here, the elastic support member 4 and the base attachment member 45 are integrally fixed by insert molding or insertion and being fixed by adhesion or the like.

  The drive means 5 includes a tilt coil 51 attached to the lower surface of the support 3 and a tilt dipole magnetized magnet 52 attached to the base 8 so as to face the coil 51. The dipole magnetized magnet 52 is formed in a flat plate shape and is fixed on the base 8 with an adhesive or the like.

  The elastic support member 4 is integrated with the tilt coil 51 by being inserted into the support attachment member 44 to which the tilt coil 51 is joined, and the support attachment piece 42 is joined to the lower surface side of the support 3. Then, it is fixed to the support 3 by being screwed with a fixing screw. The elastic support member 4 is fixed by placing the support 3 on the support mounting piece 42, and the base mounting member 45 is fixed to the base 8, thereby tilting the support 3 with respect to the base 8. Support as possible.

  The elastic support member 4 and the above-described support 3 and support arms 6a to 6f function as a displacement support mechanism that supports the lens holder 2 so as to be movable in the focus direction F and the tracking direction T.

  As shown in FIGS. 3 and 11, the dipole magnetized magnet 52 has N poles with the tangential direction Tz perpendicular to the focus direction F and the tracking direction T of the first and second objective lenses 21 and 22 as polarization lines. And the S pole are fixed. In addition, the elastic support member 4 is fixed so that a bent portion that is a connecting portion between each leg piece 41 and the support attachment piece 42 is parallel to the tangential direction Tz.

  By the way, as shown in FIGS. 3 and 11, the pair of leg pieces 41, 41 constituting the elastic support member 4 is inclined so that a gap is widened from the support attachment piece 42 side toward the base attachment member 45 side. Is provided. The pair of leg pieces 41, 41 inclined to each other has the center of gravity of the objective lenses 21, 22 at the same height as the intersection of the virtual lines extending toward the support 3 supported on the support attachment piece 42. Are formed so that their heights substantially coincide. Therefore, the elastic support member 4 is formed in a trapezoid shape as a whole.

  The dipole magnetized magnet 52 is fixed on the base 8 so as to face the coil 51 between the pair of leg pieces 41 and 41.

  When a drive current is supplied to the coil 51 for tilting, a force that moves the coil 51 with respect to the dipole magnetized magnet 52 by the action of the current flowing through the coil 51 and the magnetic field of the dipole magnetized magnet 52. That is, a force for driving the elastic support member 4 and the support 3 supported by the base 8 is generated. The elastic support member 4 is formed of an elastic member such as a leaf spring, has a pair of non-parallel leg pieces 41 and 41, and is supported by the elastic support member 4 having a trapezoidal shape as a whole. When it is received, its posture is changed following the shape of the elastic support member 4.

  By the way, the elastic support member 4 has a predetermined width so as to have rigidity against torsion. The elastic support member 4 receives the driving force when the support attachment piece 42 is fixed to the support 3 and the end of each leg piece 41 is fixed to the base 8 via the base attachment member 45. Each leg piece 41, 41 can be elastically deformed like a bow. Further, the bent portion that becomes the connecting portion between the leg pieces 41 and 41 and the support attachment piece 42 can also be elastically deformed.

  Next, the operation of the optical pickup 1 provided with the driving means 5 for driving the support 3 as described above will be described.

  The optical pickup 1 is in a neutral state without deformation of the elastic support member 4 when no power is supplied to the coil 51 of the driving means 5. At this time, the shape and the like of the elastic support member 4 are set so that the first and second objective lenses 21 and 22 supported by the lens holder 2 are horizontal.

  In this state, when a drive current is supplied to the coil 51, the current flows through the coil 51 in the magnetic field of the two-pole magnetized magnet 52, so that the support 3 is in the extending direction of the two-pole magnetized magnet 52. A driving force is generated along the tracking direction T in a substantially horizontal direction. Since the support 3 is supported by a trapezoidal elastic support member 4 having a pair of non-parallel leg pieces 41, 41, the posture of the support 3 becomes the shape of the elastic support member 4 when receiving a driving force. It is controlled by copying.

  That is, when a force for driving the support 3 in a substantially horizontal direction is applied, one leg piece 41 of the elastic support member 4 is elastically deformed in a direction in which an angle with respect to the plane of the base 8 becomes smaller, and the other leg piece 41 is 8 is elastically deformed in a direction in which the angle with respect to the plane is increased. Thereby, the support body 3 inclines in the tilt direction that is the direction around the axis of the tangential direction Tz.

  Since the support body 3 supports the lens holder 2 with the six support arms 6a to 6f, when the support body 3 is tilted, the lens holder 2 is tilted. Thus, according to a predetermined control signal By supplying the drive current to the coil 51, the tilt angle is controlled so that the optical axes of the first and second objective lenses 21 and 22 supported by the lens holder 2 are tilted in accordance with the warp of the optical disk. be able to. The direction of inclination of the support 3 is switched by the direction of the drive current supplied to the coil 51. Further, the inclination angle of the support 3 can be adjusted to a predetermined angle by the drive current voltage value supplied to the coil 51.

  As described above, the driving unit 5 can apply a driving force for tilting the support 3 in the tilt direction to the support 3 by passing a drive current through the coil 51 for tilting, and is supported by the support 3. The lens holder 2 and the objective lenses 21 and 22 can be tilted. Therefore, the objective lenses 21 and 22 can be tilted according to the warp of the optical disk.

  As described above, if the driving means 5 for driving the support 3 is provided and the lens holder 2 is inclined, the amount corresponding to the warp of each optical disk can be provided by providing the means for detecting the inclination of the optical disk. Thus, the first and second objective lenses 21 and 22 can be tilted so that the optical axes of the first and second objective lenses 21 and 22 are perpendicular to the surface of the optical disc. Thereby, the shape of the light spot formed by condensing the light beam on the signal recording surface of the optical disc can always be made appropriate. Moreover, the operation | work which adjusts the inclination of the lens holder 2 manually is also unnecessary.

  Next, focus control and tracking control of the lens holder 2 will be described. When a drive current corresponding to the focus control signal generated from the reproduction signal is supplied to the focus coils 12a to 12d, the current flowing through the focus coils 12a to 12d, the yoke 18 and the yoke pieces 18a and 18b, and the yoke pieces 18a and 18a, The force generated by the action of the magnetic field formed by the magnets 13 and 14 supported by 18b causes the lens holder 2 to move in the optical axis direction of the first and second objective lenses 21 and 22 according to the direction of the drive current. A force in the direction of ascending or descending is generated in parallel. Since the lens holder 2 is supported by one end of the six support arms 6a to 6f, the lens holder 2 maintains a parallel posture with respect to the optical disk 102 rotated by the spindle motor 103 when receiving a force in the up-and-down direction. Move up and down. Thereby, the objective lenses 21 and 22 are focus-controlled in the direction along the optical axis, and the light spot from the objective lenses 21 and 22 is focused on the track of the optical disc.

  When a drive current corresponding to the tracking control signal generated from the reproduction signal is supplied to the tracking coils 11a and 11b, the current flowing through the coils 11a and 11b, the yoke 18 and the yoke pieces 18a and 18b, and the yoke pieces The force generated by the action of the magnetic field formed by the magnets 13 and 14 supported by the magnets 18a and 18b causes the lens holder 2 to rotate in the inner circumferential direction of the optical disk 102 rotated by the spindle motor 103 according to the direction of the current. Alternatively, a force for moving the optical disk 102 in the outer peripheral direction is generated. Since the lens holder 2 is supported by one end of the six support arms 6a to 6f, when receiving a force in a direction moving in a direction parallel to the plane of the optical disc 102, the lens holder 2 of the recording track formed on the optical disc 102 is obtained. Moves and displaces in a direction almost parallel to the normal direction. As a result, tracking control is performed in which the first and second objective lenses 21 and 22 are controlled to move in the radial direction of the optical disc 102, and the light beams emitted from the first and second objective lenses 21 and 22 are obtained as desired. The recording track can be traced.

  The objective lens driving device 7 configured as described above and the optical pickup 1 using the same include the focus coils 12a to 12d, the tracking coils 11a and 11b, and the magnets 13 and 14, thereby elastically supporting the support arms 6a to 6f. By displacing, the objective lenses 21 and 22 held by the lens holder 2 can be driven and displaced in the focus direction F and the tracking direction T.

  Further, the objective lens driving device 7 and the optical pickup 1 are held by the support 3 and the lens holder 2 by elastically displacing the elastic support member 4 by including the tilt coil 51 and the dipole magnetized magnet 52. The objective lenses 21 and 22 can be driven and displaced in a tilt direction that is a direction around an axis with the tangential direction Tz as an axis.

  The optical pickup 1 can stably drive and control the objective lenses 21 and 22 with a small driving current. The optical disc apparatus using the optical pickup 1 can realize power saving, focus error signal, tracking. The objective lenses 21 and 22 can be accurately driven and displaced in accordance with the error signal and the tilt control signal, and information signal recording or reproduction characteristics can be improved.

  By the way, in the optical pickup 1, the rolling Xro generated around the axis about the tangential direction Tz of the lens holder 2, the rolling Yro generated around the axis about the tracking direction T, and the focus direction F as the axes. When unnecessary resonance such as rolling Zro occurs in the direction around the axis as described above, degradation of servo characteristics becomes a problem.

  As one of the factors that cause this unnecessary resonance, as described above (see FIG. 19), when the lens holder 2 is displaced in the focus direction F, for example, as shown in FIG. If the center of the operating point of the driving thrust ft1 and the position of the center of gravity G of the lens holder 2 are deviated in the focus direction F, the rotational force f1 due to the driving thrust ft1 of the tracking coils 11a and 11b is caused by this misalignment. And unnecessary resonance such as rolling Xro occurs. Further, the rolling Xro due to the driving thrust ft1 of the tracking coils 11a and 11b is caused when there is a deviation between the center of action of the driving thrust ft1 and the center of gravity G of the lens holder 2 when the lens holder 2 is not displaced in the focus direction F. Also occurs.

  Further, as a cause of unnecessary resonance, when the lens holder 2 is driven to the other side T1 in the tracking direction T, for example, as shown in FIGS. 13 and 14, the focus coils 12a to 12 provided in the lens holder 2 are used. 12d and the positions of the tracking coils 11a and 11b and the positions facing the magnets 13 and 14 change. Specifically, of the right and left focus coils, the right focus coils 12a and 12d approaching the center side of the magnet. The strength of the magnetic field is increased and the driving thrust ff1 is increased. On the other hand, the strength of the magnetic field of the left focus coils 12b and 12c approaching the end of the magnet is decreased and the driving thrust ff2 is decreased. The driving thrust balance of each coil of the coil is lost, and a rotational force f2 is generated. There is a risk that an unwanted resonance of a like occurs.

  In the optical pickup 1, the right focus coils 12a and 12d provided on one side of the lens holder 2 and the left focus coils 12b and 12c provided on the other side respectively have a focus direction of the lens holder 2 and A driving current determined according to the position in the tracking direction is supplied, and the difference in driving thrust generated by the influence of the magnetic field by the magnets 13 and 14 is canceled according to the position of the lens holder 2, and according to the position of the lens holder 2. Thus, the rolling Xro caused by the deviation between the center position of the driving thrust and the center of gravity of the lens holder 2 is canceled, and the occurrence of the rolling Xro is prevented.

  Specifically, when the lens holder 2 is driven in the state shown in FIGS. 13 and 14, the coefficient K (z, y) corresponding to the focus position is the focus differential coefficient calculation unit 67. And a drive current If1 corresponding to the coefficient K (z, y) is supplied to the right focus coils 12a and 12d. Similarly, a drive current If2 corresponding to the coefficient K (z, y) is supplied to the left focus coil 12b, 12c. Here, at the positions shown in FIGS. 13 and 14, when the coefficient K (z, y) is 0.5 or less, the drive current supplied to the right focus coils 12a and 12d is changed to the left focus coil 12b. , 12c, the influence of the change in the magnetic field is canceled out, and the left and right driving thrusts are made equal to ff3 and ff4 indicated by broken lines.

  As shown in FIG. 12, when the center of gravity position of the lens holder 2 and the center position of the driving force of the tracking coil are shifted, a coefficient At (z, y) corresponding to the position of the lens holder 2 is obtained. A drive current calculated by the focus tracking conversion coefficient calculation unit 68 and corresponding to the coefficient At (z, y) is supplied to the right focus coils 12a and 12d. Similarly, the drive corresponding to the coefficient At (z, y) is driven. The current If2 is supplied to the left focus coils 12b and 12c. Here, when the coefficient At (z, y) is set to be negative (−), the drive current supplied to the right focus coils 12a and 12d is made smaller than the drive current supplied to the left focus coils 12b and 12c. As a result, the driving thrust by the coils 12a and 12d becomes small as ff5 indicated by a broken line, the driving thrust by the coils 12b and 12c increases by ff6 indicated by a broken line, and the rotational force caused by the difference between the left and right driving thrusts This cancels rolling Xro.

  The optical pickup 1 to which the present invention is applied has the focus direction and tracking of the lens holder 2 in the focus coils 12a and 12d provided on one side of the tracking direction and the focus coils 12b and 12c provided on the other side. By independently supplying a driving current determined according to the position (z, y) in the direction, the driving thrust by the focus coils 12a and 12d provided on one side and the focus provided on the other side It is possible to prevent a difference from occurring in the driving thrust by the coils 12b and 12c, and to suppress unnecessary resonance caused by the rolling Xro generated in the direction around the axis in the tangential direction, thereby obtaining high servo stability. That is, the optical pickup 1 to which the present invention is applied can obtain a good servo characteristic without providing a complicated adjustment process, and can perform good recording and / or reproduction of an information signal with respect to an optical disc. It is possible to improve vibration resistance and reduce seek time by suppressing vibration mode excitation, and to reduce drive power and heat generation by reducing tracking disturbance.

  In the optical pickup 1 described above, the focus position calculation unit 65 calculates the focus position z based on the focus drive current Fd, and the tracking position calculation unit 66 calculates the tracking position y based on the tracking drive current Td. However, the present invention is not limited to this, and the focus position z and tracking position y of the lens holder 2 may be calculated by a measuring unit such as a sensor, and the signal from the detector 23 is processed. The tracking position y or the like may be calculated based on the obtained center error signal or the like.

  Next, the optical pickup 80 configured to obtain the tracking position y based on the center error signal will be described. The optical pickup 80 is common to the optical pickup 1 described above except for the configuration of the DSP. In the following description, common parts are denoted by the same reference numerals and detailed description thereof is omitted.

  In the optical pickup 80, the support arms 6a to 6f function as drive current supply means for supplying the drive current determined by the DSP 81 to the focus coils 12a to 12d and the tracking coils 11a and 11b, as described above.

  Here, the DSP 81 provided in the control circuit unit 109 that determines the drive current supplied to each of the coils 11a, 11b, 12a to 12d will be described with reference to FIG.

  Similarly to the DSP 60, the DSP 81 includes a first control calculation unit 63, a second control calculation unit 64, a focus position calculation unit 65, a focus differential coefficient calculation unit 67, a focus tracking conversion coefficient calculation unit 68, an adder 69, and A subtractor 70 is provided.

  Here, the focus differential coefficient calculation unit 67 and the focus tracking conversion coefficient calculation unit 68 include the focus position z of the lens holder 2 calculated by the focus position calculation unit 65 and the center error signal supplied via the matrix amplifier 61. The coefficient K (z, y) and the coefficient At (z, y) are determined based on the tracking position y of the lens holder 2 based on CE.

  The focus differential coefficient calculation unit 67, the focus tracking conversion coefficient calculation unit 68, the adder 69, and the subtractor 70 are based on the coefficient K (z, y) and the coefficient At (z, y) as described above. Similarly to the above, the drive currents If1 and If2 calculated by the equations (1) and (2) are supplied to the focus coils 12a to 12d via the drive amplifier circuits 72 and 73, respectively.

  In the optical pickup 80 to which the present invention is applied, the focus direction and tracking of the lens holder 2 are added to the focus coils 12a and 12d provided on one side of the tracking direction and the focus coils 12b and 12c provided on the other side. By independently supplying a driving current determined according to the position (z, y) in the direction, the driving thrust by the focus coils 12a and 12d provided on one side and the focus provided on the other side It is possible to prevent a difference from occurring in the driving thrust by the coils 12b and 12c, and to suppress unnecessary resonance caused by the rolling Xro generated in the direction around the axis in the tangential direction, thereby obtaining high servo stability. That is, the optical pickup 80 to which the present invention is applied can obtain a good servo characteristic without providing a complicated adjustment process, and can perform good recording and / or reproduction of an information signal with respect to an optical disc. It is possible to improve vibration resistance and reduce seek time by suppressing vibration mode excitation, and to reduce drive power and heat generation by reducing tracking disturbance.

  Further, the present invention is not limited to the optical pickup having the driving means 5 including the coil 51 and the magnet 52 independently for tilting as described above, but only for tilting from the viewpoint of simplification of the configuration and miniaturization of the apparatus. Of the plurality of focus coils, for example, a so-called differential having a configuration that drives in the tilt direction by providing a difference in the driving force of the focus coils arranged in the tracking direction T, for example. The present invention may be applied to a tilt type optical pickup. The differential tilt optical pickup 90 has the same configuration as the optical pickup 1 described above except that the elastic support member 4 and the driving means 5 are not required and will be described below.

  When the present invention is applied to a differential tilt optical pickup 90, a DSP 91 as shown in FIG. 16 is used to enable a tilt operation using a plurality of focus coils 12a to 12d, and to a lens holder. Rolling Xro can also be suppressed when the influence of the magnetic field on each coil changes due to displacement of 2 in the focus direction and tracking direction.

  As with the above-described DSP 81, the DSP 91 includes a first control unit 63, a second control unit 64, a focus position calculation unit 65, a focus differential coefficient calculation unit 67, a focus tracking conversion coefficient calculation unit 68, an adder 69, and A tilt drive current as a tilt component that includes the subtractor 70 and tilts the lens holder 2 so as to have a predetermined tilt angle (an angle in a tilt direction that is a direction around an axis with the tangential direction Tz as an axis). A tilt angle target value generation unit 92 that generates (tilt signal). The tilt angle target generator 92 generates a drive current for tilt for obtaining a driving force in a desired tilt direction based on a jitter amount or the like.

  Further, the DSP 91 further adds the drive current for tilt to the drive current If1 obtained by adding the drive currents from the focus differential coefficient calculation unit 67 and the focus tracking conversion coefficient calculation unit 68 by the adder 69, thereby driving the drive current. Tilt drive from the drive current If2 obtained by subtracting the drive current from the second adder 93 for generating If1 ′, the focus differential coefficient calculation unit 67 and the focus tracking conversion coefficient calculation unit 68 by the subtractor 70 And a second subtractor 94 that further subtracts the current to generate a drive current If2 ′.

  In this case, the second amplifying circuit 72 amplifies the drive current If2 'obtained by the second subtractor 94 and supplies it to the left focus coils 12b and 12c. The third amplifier circuit 73 amplifies the drive current If1 'obtained by the second adder 93 and supplies the amplified drive current If1' to the right focus coils 12a and 12d.

  As described above, the current obtained by adding the tilt component due to the tilt signal is supplied to the right focus coils 12a and 12d provided on one side in the tracking direction T, and the left focus coil 12b provided on the other side in the tracking direction T. , 12c is configured such that a current obtained by subtracting the tilt component by the tilt signal is supplied, so that it is possible to operate in the tilt direction using a plurality of focus coils without providing independent tilt coils and magnets. To do.

  Further, when applied to the differential tilt optical pickup 90, the focus coils 12a and 12d provided on one side of the tracking direction and the other side are provided as in the optical pickup 1 described above. A focus coil provided on one side by independently supplying a drive current determined according to the position (z, y) of the focus direction and tracking direction of the lens holder 2 to the focus coils 12b and 12c. It is possible to prevent a difference between the driving thrust by 12a and 12d and the driving thrust by the focus coils 12b and 12c provided on the other side, and unnecessary by the rolling Xro generated around the axis in the tangential direction. Resonance can be suppressed and high servo stability can be obtained.

  In the above description, the driving current determined according to the position of the lens holder 2 in the focus direction and the tracking direction is supplied to the focus coils provided on one side and the other side in the tracking direction, respectively. Although it is configured to suppress unnecessary resonance, as in the case of application to a differential tilt optical pickup, based on the position of the lens holder calculated by the focus position calculation unit and the tracking position calculation unit, or the coefficient K ( Based on z, y) and the coefficient At (z, y), by supplying a corresponding drive current for the tilt coil 51 to the tilt coil, a rotational force that cancels the rolling Xro described above is generated, and the rolling Xro You may comprise so that the unnecessary resonance by may be suppressed.

  Next, an optical pickup 95 configured to supply a drive current determined according to the position of the lens holder to the tilt coil will be described with reference to FIG. The optical pickup 95 is common to the optical pickup 1 described above except for the configuration of the DSP. In the following description, common parts are denoted by common reference numerals and detailed description thereof is omitted.

  The DSP 96 includes a first control unit 63, a second control unit 64, a focus position calculation unit 65, a tracking position calculation unit 66, and a tilt angle target value generation unit 92, similar to the above-described DSPs 60 and 91. Inclination conversion coefficient calculation for determining a coefficient for determining the drive current supplied to the tilt coil 51 based on the focus position and tracking position of the lens holder 2 calculated by the focus position calculation unit 65 and the tracking position calculation unit 66. And an adder 98 that adds the drive current determined by the tilt angle target value generation unit 92 and the drive current determined by the tilt conversion coefficient calculation unit 97.

  Based on the drive current determined by the tilt angle target value generation unit 92 and the tilt conversion coefficient calculation unit 97, the adder 98 supplies the tilt coil drive current Iti to the tilt coil 51 via the drive amplification circuit 71 described later. Supply.

  The optical pickup 95 to which the present invention is applied includes a tilt coil 51 that generates a tilt direction driving force that tilts the lens holder 2 in a direction around the axis in the tangential direction, and a position (z, By supplying a drive current determined in accordance with y), it is possible to suppress unnecessary resonance due to rolling Xro generated in the direction around the axis in the tangential direction and obtain high servo stability. That is, the optical pickup 95 to which the present invention is applied can obtain a good servo characteristic without providing a complicated adjustment process, and can perform good recording and / or reproduction of an information signal with respect to an optical disc. It is possible to improve vibration resistance characteristics by suppressing excitation of the vibration mode and to shorten the seek pull-in time, and to reduce driving power and to suppress heat generation by reducing tracking disturbance.

  In the optical disk apparatus 101 using these optical pickups 1, 80, 90, and 95, rolling can be suppressed by adjusting the driving thrust by the coils provided on one side and the other side of the lens holder 2. Thus, it is possible to obtain good servo characteristics without providing a complicated adjustment process, and it is possible to perform good recording and / or reproduction of information signals with respect to the optical disc.

1 is a block circuit diagram of an optical disc apparatus using an optical pickup to which the present invention is applied. 1 is a perspective view of an optical pickup to which the present invention is applied. It is a perspective view of the objective lens drive device which comprises the optical pickup to which this invention is applied. It is a perspective view of a lens holder and a support that constitute an optical pickup to which the present invention is applied. It is a perspective view which shows the lens holder and support body which comprise the optical pick-up to which this invention is applied. It is a figure which shows the magnetization pattern of the magnet which comprises the optical pick-up to which this invention is applied, (a) is a top view from the lens holder side of the 1st magnet arrange | positioned at the front end side, (b) These are top views from the lens holder side of the 2nd magnet arrange | positioned at the base end part side. It is a block circuit diagram for demonstrating the structure of DSP which determines the drive current supplied to each coil. It is a perspective view of the objective lens drive device which comprises the optical pick-up for demonstrating the example which arranged the objective lens in the radial direction as another example of the optical pickup to which this invention is applied. It is a figure which shows the change of the surroundings of a rolling phase accompanying the change of the gain ratio of the focus coil provided in one and the other of the tracking direction of the optical pick-up shown in FIG. It is a figure which shows the frequency characteristic of the objective lens drive device which comprises the optical pick-up shown in FIG. It is a disassembled perspective view of the elastic support member which comprises the optical pick-up shown in FIG. 2, and supports the support body so that tilting is possible, and the drive means which drives a support body. In the optical pickup to which the present invention is applied, it is a front view showing a state in which rolling Xro occurs when the center of the acting point of the driving force of the tracking coil is shifted from the center of gravity of the lens holder. In the optical pickup to which the present invention is applied, when the lens holder is driven in the tracking direction, the rolling Xro is generated due to the difference in driving thrust between the right and left focus coils. It is a top view which shows the front end side of the optical pick-up in the state shown in FIG. It is a block circuit diagram for demonstrating the structure of DSP in the other example of the optical pick-up to which this invention is applied. 1 is a block circuit diagram for explaining a configuration of a DSP when the present invention is applied to a differential tilt optical pickup. FIG. It is a block circuit diagram for demonstrating the structure of DSP in the further another example of the optical pick-up to which this invention is applied. It is a top view of the movable part of the objective lens drive device which comprises the conventional optical pick-up. In the conventional optical pickup, it is a front view which shows the state which rolling Xro generate | occur | produced when the center of the action point of the drive thrust of a tracking coil and the gravity center position of a lens holder have shifted | deviated. FIG. 10 is a front view showing a state in which rolling Xro is generated due to a difference in driving thrust between right and left focus coils in a state where a lens holder is driven in a tracking direction in a conventional optical pickup. It is a block circuit diagram for demonstrating the structure of DSP of the conventional optical pick-up. It is a block circuit diagram for demonstrating the structure of DSP of the conventional optical pick-up of a differential tilt system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Optical pickup, 2 Lens holder, 3 Support body, 4 Elastic support member, 5 Drive means, 6a-6f Support arm, 8 Base, 11a, 11b Tracking coil, 12a-12d Focus coil, 13, 14 Magnet, 18 York, 21 First objective lens, 22 Second objective lens, 41 Leg piece, 51 Tilt coil, 52 Tilt magnet, 101 Optical disc device, 102 Optical disc, 103 Spindle motor

Claims (5)

An objective lens that focuses the light beam is attached to the signal recording surface of the optical disk that is driven to rotate, and moves in a focus direction parallel to the optical axis of the objective lens and a tracking direction orthogonal to the optical axis direction of the objective lens A lens holder,
A support body disposed with a gap in the tangential direction orthogonal to the focus direction and the tracking direction with respect to the lens holder;
An elastic support member that connects the lens holder and the support, respectively, and supports the lens holder movably in the focus direction and the tracking direction with respect to the support;
A focus coil provided in the lens holder and provided in at least one pair in the tracking direction to generate a driving force in the focus direction;
A tracking coil provided in the lens holder and generating a driving force in the tracking direction;
At least a pair of magnets disposed opposite to the focus coil and the tracking coil;
Drive current supply means for independently supplying a drive current to the focus coil provided on one side of the tracking direction and the focus coil provided on the other side of the tracking direction;
A driving current determined according to the position of the lens holder in the focus direction and the tracking direction is supplied to the focus coil provided on the one side and the focus coil provided on the other side, respectively. Optical pickup to be used.   The focus coil provided on the one side and the focus coil provided on the other side each include a center of driving force of the tracking coil that changes according to the position of the lens holder in the focus direction. 2. The optical pickup according to claim 1, wherein a driving current determined so as to cancel the rotational force around the axis in the tangential direction generated by a deviation from the center of gravity of the lens holder is supplied.   The focus coil provided on the one side and the focus coil provided on the other side are respectively provided with the focus provided on the one side that changes according to the position of the lens holder in the tracking direction. 2. The optical pickup according to claim 1, wherein a driving current determined so as to cancel a difference in driving force due to the influence of the magnetic field by the pair of magnets on the coil and the focus coil provided on the other side is supplied. The elastic support member supports the lens holder so as to be movable in the focus direction and the tracking direction with respect to the support body, and supports the lens holder so as to be tiltable in a tilt direction inclined about the axis in the tangential direction. ,
The focus coil generates a driving force in the focus direction and drives in the tilt direction by providing a difference between the driving force of the focus coil on the one side and the driving force of the focus coil on the other side. The optical pickup according to claim 1, wherein a force is generated. An objective lens that focuses the light beam is attached to the signal recording surface of the optical disk that is driven to rotate, and moves in a focus direction parallel to the optical axis of the objective lens and a tracking direction orthogonal to the optical axis direction of the objective lens A lens holder,
A support body disposed with a gap in the tangential direction orthogonal to the focus direction and the tracking direction with respect to the lens holder;
An elastic support member that connects the lens holder and the support, respectively, and supports the lens holder movably in the focus direction and the tracking direction with respect to the support;
A focus coil provided on the lens holder and generating a driving force in the focus direction;
A tracking coil provided in the lens holder and generating a driving force in the tracking direction;
At least a pair of magnets disposed opposite to the focus coil and the tracking coil;
A tilt coil for generating a driving force in a tilt direction in which the lens holder is tilted in a direction around the tangential axis;
A tilt magnet disposed opposite to the tilt coil,
An optical pickup in which a driving current determined in accordance with the position of the lens holder in the focus direction and the tracking direction is supplied to the tilt coil.

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