JP2009037671A - Optical pickup device and optical disk unit using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a flaw and wear mark of an optical disk due to an interference between an objective lens and the optical disk. <P>SOLUTION: An optical disk unit for recording/reproducing information by selectively radiating a plurality of laser beams with different wavelengths to a plurality of optical disk types comprises: a light source for radiating the plurality of laser beams with different wavelengths; first and second objective lenses 23 and 24 having different specifications; a lens holder 12 on which the first and second objective lenses 23 and 24 are mounted to be moved in the focusing direction in parallel with the optical axes of the first and second objective lenses 23 and 24 and in the tracking direction orthogonal to the focusing direction; and a supporting section 13 for movably supporting the lens holder 12 in the focusing and tracking directions. A case for the lens holder 12 is formed in such a way that one end or both ends in the radial direction of the case have steps 12a and 12b to separate from the optical disk. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical pickup apparatus that records and / or reproduces information signals with respect to an optical disc, and includes an optical element driving unit that drives an optical element provided in the optical path in the optical axis direction. The present invention relates to an optical disc apparatus using the same.

  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 device that moves in the radial direction of the optical disc and irradiates the optical disc with a light beam.

  Such an optical pickup device includes a lens holder that holds an objective lens, and includes an actuator that drives the lens holder in, for example, a focus direction and a tracking direction. By driving and displacing the lens holder, the objective lens is provided. The light beam condensed by the above can be appropriately focused on the recording layer of the optical disc. In such an optical pickup device, it is necessary to prevent damage caused by interference between the objective lens and the lens holder to be driven and the optical disc, that is, to avoid the interference itself. This interference is particularly severe with respect to the collision with the inner and outer ribs (protrusions) of the optical disc when the lens holder is located at the innermost or outermost periphery, and it is necessary to avoid this collision. It was.

  The above-described optical pickup apparatus compatible with the conventional DVD and CD has a wide working distance (hereinafter also referred to as “WD”). There was no need to consider height and radial constraints. In addition, a protective member may be provided to prevent damage due to an unexpected collision between the objective lens and the optical disk. As a shape of the protector as such a protective member, a resin dough-shaped molding is used as the lens. It was common to cover it with a UV curable adhesive.

  In recent years, as a next-generation optical disc format, an optical disc capable of high-density recording (hereinafter, also referred to as a “high-density recording optical disc”) that records and reproduces signals using a light beam with a wavelength of about 405 nm by a blue-violet semiconductor laser has been proposed. Has been. In providing an optical pickup device compatible with these high-density recording optical discs, an optical pickup device compatible with a conventional CD having a used wavelength of about 785 nm and a DVD having a used wavelength of about 660 nm (hereinafter referred to as “three-wavelength compatible”). It is also called “optical pickup device”).

  However, in such a three-wavelength optical pickup device, the working distance is very small, and there is a concern about interference with the inner and outer peripheral ribs of the optical disc when accessing the inner and outer periphery of the optical disc. The only way to increase the working distance is to increase the diameter of the objective lens. As the diameter of the objective lens increases, the size of the actuator increases and the weight increases, resulting in a decrease in sensitivity. For example, the recording / reproducing characteristics cannot be satisfied.

  In addition, as a material for the protector, in an optical pickup device compatible with DVD and CD, POM having excellent slidability is generally used from the viewpoint of protecting the optical disk. If there is a collision, wear marks adhere to the surface of the optical disk, and a high-density recording optical disk with a thin recording layer immediately causes a recording and / or reproduction error.

  In addition, in the optical pickup device dedicated to high-density recording optical discs, the coating type is used. However, this coating type causes a deep scratch that cannot be wiped onto optical discs such as DVD and CD without hard coating. was there.

  As described above, in an optical pickup device that records and / or reproduces information on a plurality of types of optical disks such as high-density recording optical disks, DVDs, and CDs, the optical disk is affected by interference between the objective lens and the lens holder and the optical disk. There was a problem of scratches and wear marks.

JP 2002-197704 A

  The object of the present invention is to scratch or wear the optical disk due to interference between the optical disk holding the objective lens and driven at least in the focus direction and the tracking direction, and the objective lens held in the lens holder. It is an object of the present invention to provide an optical pickup device and an optical disk device using the same.

  In order to achieve this object, an optical pickup device according to the present invention selectively irradiates a plurality of types of optical beams with different wavelengths onto a plurality of types of optical discs mounted at a common mounting position of a disc table. Accordingly, in the optical pickup device that records and / or reproduces information, a light source that emits a plurality of light beams having different wavelengths, first and second objective lenses having different specifications, and the first And a second objective lens, a lens holder that is moved in a focus direction parallel to the optical axis of the first and second objective lenses, and a tracking direction orthogonal to the focus direction, and the lens holder A support portion that is movably supported in the focus direction and the tracking direction, and the lens holder housing has one end side in the radial direction or Portion of both ends is formed with a stepped so as to be separated from said loaded optical disk.

  In order to achieve this object, an optical disc apparatus according to the present invention is provided for a disc table for mounting and rotating a plurality of types of optical discs, and a plurality of types of optical discs mounted at a common mounting position of the disc table. The optical pickup device includes an optical pickup device that records and / or reproduces information by selectively irradiating a plurality of light beams with different wavelengths. This is what I used.

  In the present invention, the housing of the lens holder holding the first and second objective lenses is formed with a step so as to be separated from the optical disc on which one end side or both end sides in the radial direction are mounted. By doing so, it is possible to prevent the optical disc from being scratched or worn due to interference between the lens holder and the optical disc.

  Hereinafter, an optical disk device using an optical pickup device to which the present invention is applied will be described with reference to the drawings. As shown in FIG. 1, the optical disc apparatus 101 is a recording / reproducing apparatus that records and / or reproduces information signals with respect to the optical disc 102.

  As the optical disk 102 to be recorded and / or reproduced by the optical disk device 101, for example, a CD (Compact Disc), a DVD (Digital Versatile Disc), a CD-R (Recordable) and a DVD-R (information recordable) are available. Recordable), CD-RW (ReWritable), DVD-RW (ReWritable), DVD + RW (ReWritable), and other optical disks that can be rewritten, and semiconductor lasers with a shorter emission wavelength of about 405 nm (blue-violet) An optical disk capable of high-density recording, a magneto-optical disk, or the like is used.

  As shown in FIG. 1, the optical disk apparatus 101 includes a disk table on which a plurality of types of optical disks 102 as described above are mounted and rotated, a spindle motor 103 as drive means for rotating the disk table, a disk table An optical pickup device 1 for recording and / or reproducing information by selectively irradiating a plurality of light beams having different wavelengths to a plurality of types of optical disks 102 mounted at a common mounting position; A feed motor 105 is provided as a driving means for moving the pickup device 1 in the radial direction. 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 device 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 102 are reproduced.

  Further, the optical pickup device 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 uses the signal processing unit 120 to detect detection signals obtained from the respective light beams. It is comprised so that it may supply.

  The signal processing unit 120 generates various servo signals, that is, a focus error signal and a tracking error signal, based on detection signals obtained by detecting each light beam, and further uses information signals recorded on the optical disc 102. An RF signal is generated. Also, predetermined processing such as demodulation and error correction processing based on these signals is performed by the control circuit unit 109, the signal modulation and 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 and ECC block 108 is, for example, for data storage of a computer, 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.

  Also, if the recording signal demodulated by the signal modulation and 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 for audio / visual processing. Supplied to the 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 device 1. The optical pickup device 1 is moved 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. Control of the spindle motor 103, control of the feed motor 105, and control of the actuator that moves and displaces the objective lens of the optical pickup device 1 in the focus direction of 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.

  Further, the control circuit unit 109 is driven to supply a tracking coil and a focus coil provided in the optical pickup device 1 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 the laser light source in the optical pickup device 1.

  Here, the focus direction F refers to the optical axis direction of the objective lenses 23 and 24 of the optical pickup device 1, and the tangential direction Tz is a direction orthogonal to the focus direction F and is the circumference of the optical disc device 101. The direction parallel to the tangential direction is referred to, and the tracking direction T is a direction orthogonal to the focus direction F and the tangential Tz direction.

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

  The optical pickup device 1 records and / or reproduces an information signal on 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. The optical disk device 1 is used, specifically, a first optical disk on which an information signal is recorded or reproduced using a light beam having a first wavelength of about 760 to 800 nm, and a wavelength of 650 to 660 nm. A second optical disk on which information signals are recorded or reproduced using a light beam with a second wavelength of the order, and a recording or reproduction of information signals using a light beam with a third wavelength of about 400 to 410 nm. A description will be given on the assumption that an information signal is recorded and / or reproduced with respect to the third optical disk to be performed.

  The optical pickup device 1 to which the present invention is applied is reflected from the first and second light sources 21 and 22 composed of semiconductor lasers or the like that emit a plurality of types of light beams having different wavelengths, and the signal recording surface of the optical disk 102. As a light detection element for detecting the reflected light beam, the light beams from the first and second light sources 21 and 22 are guided to the optical disk 102, and the light beam reflected by the optical disk 102 is used as the light detection element. And a guiding optical system.

  Here, the first light source 21 includes an emission unit that emits a light beam having a first wavelength and an emission unit that emits a light beam having a second wavelength. The second light source 22 includes: And an emission part for emitting a light beam of the third wavelength.

  As shown in FIGS. 2 and 3, the optical pickup device 1 has various configurations that are movable in a radial direction (hereinafter also referred to as “radial direction”) R of the optical disc 102 within the housing of the optical disc device 101. It is provided on a pickup base (OP base) 20 as a component mounting base.

  The optical pickup device 1 includes a lens holder 12 that supports a plurality of objective lenses 23 and 24 that collect a light beam emitted from a light source and irradiate the optical disk 102 as shown in FIGS. A support body 13 which is arranged at an interval in the tangential direction Tz from the holder 12 and is attached to a pickup base 20 as an attachment base, and the lens holder 12 is moved in the focus direction F and the tracking direction T with respect to the support body 13. And a plurality of support arms 14a to 14d that can be supported. The lens holder 12, the support body 13, and the support arms 14a to 14d, together with coils 51 and 52 and a magnet 53, which will be described later, an objective lens that drives the objective lenses 23 and 24 in the focus direction F and the tracking direction T as will be described later. Functions as a drive mechanism. The first and second objective lenses 23 and 24 constitute a part of the optical system of the optical pickup device 1.

  Here, the first objective lens 23 is used for condensing the light beams having the first and second wavelengths on the first and second optical disks 102, and the second objective lens 24 is used for the third objective lens 24. It is used to collect a light beam having a wavelength on the third optical disk 102. The first and second objective lenses 23 and 24 are arranged in parallel in the tangential direction Tz. Here, the 2nd objective lens 24 is provided in the support body 13 side which is a fixing | fixed part side, and the 1st objective lens 23 is provided in the front end side.

  The optical pickup device 1 is configured to include a plurality of objective lenses 23 and 24 that are arranged 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 arranged in the radial direction R, or may be configured to include one objective lens. Here, when providing a plurality of objective lenses, the radial dimension of the lens holder 12 described later can be reduced by arranging the objective lenses side by side in the tangential direction Tz. It is possible to easily avoid a collision between the lens 102 and the housing of the lens holder 12.

  As an optical system for guiding the light beams emitted from the first and second light sources 21 and 22 to the optical disc 102, at least a beam for combining the optical paths of the light beams emitted from the first and second light sources 21 and 22 is used. A splitter 25, a collimator lens 26 that converts the divergence angles of the light beams combined by the beam splitter 25 into substantially parallel light, and transmits the third wavelength light beam and the first and second light beams. A first rising mirror 27 that reflects a light beam having a wavelength and enters the first objective lens 23, and a second light beam that passes through the first rising mirror 27 and reflects the second light beam. The second raising mirror 28 that is incident on the objective lens 24 and the above-described first and second objective lenses 23 and 24 are provided. In FIG. 4, L1 indicates the optical path of the light beam emitted from the first light source 21, L2 indicates the optical path of the light beam emitted from the second light source 22, and L3 is obtained by the beam splitter 25. The optical paths of the light beams emitted from the first and second light sources 21 and 22 after being combined are shown.

  Further, the optical pickup device 1 is provided with an actuator 30 as an optical element driving means for moving the collimator lens 26 in the optical axis direction. The collimator lens 26 is moved in the optical axis direction Y by the actuator 30 so that the divergence angle of the light beam after passing through the collimator lens 26 can be changed, thereby correcting and reducing the aberration. it can. The actuator 30 includes a holding unit 31 that holds the collimator lens 26, and a drive motor 34 that drives the holding unit 31 and the collimator lens 26 held by the holding unit 31.

  As shown in FIGS. 2 and 5, the lens holder 12 is provided so as to surround the outer peripheral surfaces of the first and second objective lenses 23 and 24, and the first and second objective lenses 23 and 24 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 lenses 23 and 24 and a tracking direction T orthogonal to the optical axis. In FIG. 5, RI indicates the radial direction of the optical disc 102 toward the inner peripheral side, and RO indicates the radial direction of the optical disc 102 and toward the outer peripheral side.

  On both side surfaces of the lens holder 12 that are separated in the tracking direction T, arm support portions 15 that support the pair of support arms 14a and 14b and the support arms 14c and 14d at intervals in the focus direction F are provided. . Similarly, an arm support portion 16 that supports the support arms 14a to 14d is also provided on the support body 13 side.

  In addition, the lens holder 12 generates a tracking coil 51 that generates a driving force in the tracking direction T that is a substantially radial direction of the optical disk 102, and a driving force that generates a driving force in the focus direction F that is close to and away from the optical disk 102. A focus coil 52 is attached.

  A yoke 18 is disposed between the lens holder 12 and the pickup base 20. The yoke 18 is fixed to the pickup base 20 via a mounting base (not shown). As shown in FIG. 2, rising portions are formed on both sides of the yoke 18 in the tangential direction Tz, and a plurality of magnets 17 are attached to opposing surfaces of the rising portions. The magnet 17 is opposed to the tracking coil 51 and the focus coil 52 that are respectively attached to the opposite side surfaces of the lens holder 12, and applies a predetermined magnetic field to the coils 51 and 52 that are arranged to face each other.

  When a driving current is supplied to the tracking coil 51 and the focus coil 52, the lens holder 12 is moved in the tracking direction by the interaction between the current supplied to the coils 51 and 52 and the magnetic field from the magnet 53. Drive displacement in T and focus direction F.

  As a result, the first and second objective lenses 23 and 24 supported by the lens holder 12 are driven and displaced in the focus direction F and / or the tracking direction T, via the first and second objective lenses 23 and 24. Focus control is performed so that the light beam applied to the optical disk 102 is focused on the signal recording surface of the optical disk 102, and the light beam is controlled to follow the recording track formed on the optical disk 102. Tracking control is performed.

  The optical pickup device 1 further includes an elastic support member (not shown) that supports the support 13 supporting the lens holder 12 so as to be tiltable with respect to the base, and the support 13 supported so as to be tiltable on the elastic support member. Driving means for tilting in the tilt direction Ti, which is a direction around the axis with the tangential direction Tz as an axis, according to the tilt of the optical disk 102, and the elastic support member and the driving means constitute the objective lens driving mechanism described above. . This driving means includes a tilt coil 54 provided on both side surfaces of the support 13 in the tracking direction T, and a tilt magnet 55 attached to an attachment portion raised from the base. When a driving current is supplied to the tilt coil 54, the lens holder 12 is driven and displaced in the tilt direction Ti by the interaction between the current supplied to the tilt coil 54 and the magnetic field from the magnet 55. As described above, the driving means including the tilt coil 54 and the magnet 55 applies a driving force for tilting the support 13 in the tilt direction to the support 13, and the lens holder 12 and the objective lens 23 supported by the support 13. , 24 can be tilted in the tilt direction, and the optical spot of the objective lens 23, 24 is appropriately adjusted to the optical disc statically or dynamically as necessary to properly adjust the light spot on the signal recording surface of the optical disc. It is possible to perform so-called tilt angle tilt control to be adjusted.

  The optical pickup device 1 configured as described above has the first to third wavelengths of light from the emitting portions provided in the first and second light sources 21 and 22 in accordance with the type of the mounted optical disk 102. A light beam having a wavelength corresponding to the type of the optical disk 102 is emitted from the beam, and a light beam irradiated through the objective lens corresponding to the type of the optical disk 102 out of the first and second objective lenses 23 and 24 is predetermined. By performing focus control, tracking control, and tilt control as necessary so as to focus on and follow the recording track, information signals can be recorded on or reproduced from the optical disc 102. Then, the optical pickup device 1 drives the actuator 30 described above according to the type of the optical disc 102 and moves the collimator lens 26 provided in the optical path, so that the optical pick-up device 1 is optically compatible with a plurality of types of optical discs 102 described above. It is possible to reduce aberrations that may occur as a disadvantage of an optical system that realizes a plurality of wavelengths compatible with a common optical path, thereby realizing good recording / reproducing characteristics.

  Next, a specific configuration of the lens holder 12 described above will be described.

  As shown in FIGS. 5, 6, and 7, the housing (housing) of the lens holder 12 has steps 12 a and 12 b so as to be separated from the optical disk 102 on which both ends in the radial direction R are mounted. Is formed. That is, the lens holder 12 has a first surface 12c formed as a surface facing the optical disk 102 at substantially the same position in the focus direction F as the end of the first and second objective lenses 23 and 24 on the optical disk 102 side. The second and third portions formed on the both sides of the first surface 12c in the radial direction R so as to escape to the optical disc 102 in positions away from the first surface 12c in the focus direction F. The surfaces 12d and 12e are formed. This is because the working distance (WD) of the optical pickup device 1 that enables the three-wavelength compatibility as described above is reduced because the optical path and optical components are partly or entirely shared for each wavelength. However, in such a model having a small working distance (1 mm or less), there is a restriction such as interference with the ribs 102a and 102b which are projections existing on the inner and outer circumferences of the optical disk 102. In order to avoid this, the lens holder 12 has a stepped shape lowered by one step in the radial direction R as described above.

  The steps 12a and 12b provided on the housing of the lens holder 12 prevent interference with the ribs 102a and 102b existing on the inner and outer circumferences of the optical disk 102 by the size of the steps 12a and 12b in the focus direction F. Make it possible. That is, when the dimension in the focus direction between the signal recording surface of the optical disc 102 and the first surface 12c is L0, and the thickness (dimension in the focus direction) of the inner peripheral rib 102a of the optical disc 102 is L1, In the conventional lens holder that does not have the step 12a, the dimension L01 obtained by L0−L1 = L01 has a margin for interference. That is, when the lens holder is located on the inner periphery, the entire apparatus is shocked. When the lens holder and the optical disk 102 collide with each other when the lens holder is displaced by the dimension L01 in the focus direction F due to some cause such as unnecessary vibration when received, the lens holder having the step 12a 12, if the dimension of the step 12a in the focus direction F is Lx, the dimension L01x obtained by L01 + Lx = L01x In other words, the lens holder 12 does not collide with the optical disk 102 even if the lens holder 12 is changed in the focus direction by the dimension L01 when the lens holder 12 is located on the inner periphery. Furthermore, collision can be prevented with respect to a displacement of less than Lx minutes.

In FIG. 6, _CH denotes a center hole when mounted on the disk table, A _IN denotes an information area (Information area), A _PC denotes a power calibration area (Power Calibration area), A _LI indicates a lead-in area. In general, the lead-in area is about φ46 to 50 mm, the power calibration area is about φ45 to 46 mm, and the inside of the information area, that is, the outside of the rib is about φ44 mm at maximum. Furthermore, the dimension L1 indicating the thickness of the inner peripheral rib 102a is about 0.4 mm at the maximum, and the dimension L2 indicating the thickness of the outer peripheral rib 102b described later is about 0.1 mm at the maximum.

  Similarly, in a conventional lens holder that does not have the step 12b when the thickness (dimension in the focus direction) of the outer peripheral rib 102b of the optical disk 102 is L2, the dimension L02 obtained by L0−L2 = L02. However, there is no allowance for interference. That is, when the lens holder is positioned on the outer periphery, when the lens holder is displaced by the dimension L02 in the focus direction F, the lens holder and the optical disk 102 collide with each other. On the other hand, in the lens holder 12 having the step 12b, if the dimension of the step 12b in the focus direction is Ly, the lens holder 12 has a margin for interference by a dimension L02y obtained by L02 + Ly = L02y. Even if the position is changed by the dimension L02 in the focus direction F when Zuhoruda 12 and the optical disk 102 and is without colliding, and thus can prevent collision against further dimension Ly of less than minute displacement.

  In this way, the lens holder 12 constituting the optical pickup device 1 is formed with steps 12a and 12b so that the housing is separated from the optical disk 102 on which both end portions in the radial direction R are mounted. This prevents the lens holder 12 from interfering with the ribs 102a and 102b of the optical disk 102, and the lens holder 12 and the ribs 102a and 102b of the optical disk 102 interfere to cause scratches and wear marks on the optical disk 102. To prevent it. The lens holder 12 described here is configured to have steps 12a and 12b at both ends of the casing in the radial direction R. However, the lens holder that constitutes the optical pickup device of the present invention is provided here. However, the present invention is not limited to this, and it is only necessary that the housing of the lens holder is formed with a step so as to be separated from the optical disc 102 on which one end in the radial direction is mounted. That is, since the dimension in the thickness direction of the rib 102a on the inner peripheral side of the optical disk 102 is generally larger than the dimension in the thickness direction of the rib 102b on the outer peripheral side, one end side on the side facing the inner peripheral side If this portion has the step 12a, it is possible to prevent interference at the time of being located on the inner peripheral side where interference is more likely to occur than at the outer peripheral side.

  Further, the housing of the lens holder 12 is located on both sides of the first and second objective lenses 23 and 24 in the tangential direction Tz, and the first and second objective lenses 23 and 24 and the lens holder 12 Protector members 19a and 19b are provided as protective means having slidability and wear resistance so as to be closer to the optical disc 102 side than the first surface 12c closest to the optical disc 102 side. This is because the protector member provided in the lens holder 12 having a stepped shape lowered by one step in the radial direction R as described above is arranged so as to surround the objective lenses 23 and 24 only in the tangential direction Tz, It is configured to be accommodated within a range close to the outer shape of the objective lenses 23 and 24 as much as possible.

  The protector members 19a and 19b provided in the housing of the lens holder 12 have scratches or wear marks on the optical disk 102 when the pair of lenses 23 and 24 and the optical disk 102 collide with each other due to unnecessary vibration due to impact or the like. To prevent it. That is, the protector members 19a and 19b provided so as to be closer to the optical disc 102 than the first and second objective lenses 23 and 24 and the first surface 12c of the lens holder 12 are caused by vibration or the like. When the optical discs 102 and 24 come close to each other so as to collide, they abut against the optical disc 102 to prevent the lens holder 12 and the objective lenses 23 and 24 and the optical disc 102 from colliding with each other. At this time, the protector members 19a and 19b have both slidability and wear resistance as will be described later, thereby preventing the optical disk 102 from being scratched or worn.

  As a material of such protector members 19a and 19b, a porous polymer having a molecular weight of 1 million or more and a porosity of about 20% to 40% is used. Here, the ultra-polymer refers to a polymer having a molecular weight of 1 million or more, whereas the polymer refers to a polymer having a molecular weight of 500,000 to less than 1 million. Something about 10,000. From the characteristic test, it can be confirmed that the higher the molecular weight, the better the protector performance consisting of the slidability and wear resistance described later. Below, it demonstrates as what uses about 6 million molecular weight.

  Here, the material of the protector member will be described in detail.

  In recent years, various optical discs 102 such as high-density recording optical discs, DVDs, and CDs have been increased in speed, and the optical disc 102 and objective lenses 23 and 24 and / or lens holder 12 In the event of a collision, it is necessary to prevent damage to the optical disk 102 as much as possible from the viewpoint of protecting the contents of the optical disk 102 as well as protecting the objective lenses 23 and 24. The material is required to have high slidability and wear resistance. Conventionally, POM (polyacetal) used as a protector member is excellent in self-lubricating properties but is soft, and has a problem that foreign matters such as wear marks are likely to adhere to the optical disk 102 side due to abrasion due to collision, and wear is also fast. . Specifically, when the protector member made of POM is caused to collide with the optical disk 102A such as a DVD, there is a possibility that a wear mark K1 as shown in FIG. 8 is generated. In addition, a fluorine-based coating type is used for the optical pickup device for the high-density recording optical disk 102, but this fluorine-based coating type has a problem that a hard protective material causes a deep scratch on the disk protective film. It was. Specifically, when a protector member of a fluorine-based coating type is caused to collide with the optical disc 102B that is not hard-coated, there is a possibility that the scratch K2 as shown in FIG. .

  On the other hand, as described above, the protector members 19a and 19b of the lens holder 12 constituting the optical pickup device 1 to which the present invention is applied are made of ultrahigh molecular polyethylene having excellent wear resistance due to its properties, and the surface. By using a member made of a material that is porous and has a porosity of about 20 to 40% and that is excellent in slidability, both wear resistance and slidability are achieved. As the porous state, for example, the surface state of an open cell having a porosity of about 30% and an average pore size of about 30 μm is shown in FIG. 10A, and the cross-sectional state is shown in FIG. Shown in b).

  The protector member made of such a material, for example, with respect to the optical disk 102 having a relatively soft protective film without a hard coat, wear marks without damaging the surface of the disk protective film due to excellent slidability due to the porosity. It is possible to significantly improve the adhesion of foreign substances such as the conventional POM.

  In addition, the protector member made of such a material is unlikely to collide with the optical disk 102 having a hard coat and a hard protective film due to the wear resistance and porous slidability that are characteristic of polyethylene. In this case, the protector itself is not scraped, and foreign matter such as wear marks is prevented from adhering to the surface of the optical disk 102. Therefore, it is possible to prevent adverse effects on the recording operation / reproducing operation and the like. However, for media having a surface near the surface of the protective film, the effect can be exhibited, and problems such as reproduction errors due to foreign matter adhesion can be avoided.

  Here, an experimental example for confirming these will be described with reference to FIGS. FIG. 11 shows SER measurement results when a lens holder provided with a protector member made of POM and a high-density recording optical disk collide with each other a predetermined number of times, that is, during a collision test. 11A shows a state before the collision, and FIG. 11B shows a state in which the collision is performed with the number of collisions being one.

  On the other hand, FIG. 12 shows a case where the lens holder provided with the above-described protector member made of ultra-high molecular weight polyethylene and the high-density recording optical disc are repeatedly collided, that is, at the time of a collision test, as this example. It is a SER measurement result. 12A shows a state before the collision, and FIG. 12B shows a state where the collision is performed with the number of collisions being 500 times. Here, the horizontal axis in FIGS. 11 and 12 indicates the area where the protector collides, that is, the address range (RUB) in the radial direction of the optical disk, and the vertical axis indicates the symbol error rate (SER).

As shown in FIG. 11, when a protector member made of POM is used, a fatal error value due to the adhesion of a foreign matter occurs only by a single collision, whereas as shown in FIG. When a protector member made of ultra-high molecular weight polyethylene is used, it can be confirmed that the generated error value can be suppressed within an allowable range (within 4.0 × 10 ⁻⁰³ ) even when it is caused to collide 500 times. . In view of the above, a porous ultra-high molecular weight polyethylene material having excellent wear and sliding properties is considered to be an optimum material because of the role and performance required for the protector member of the objective lens of the optical disc apparatus 1.

  Next, a detailed configuration of the protector member will be described.

  In general, polyethylene is very poor in moldability, dimensional accuracy, and adhesiveness, and it is difficult to perform injection molding with an ultra-polymer having a molecular weight exceeding 1,000,000, so that it is like a protector member for objective lenses and lens holders. However, there are unsuitable aspects for precision small parts that require extremely high precision. Therefore, in the protector member constituting the optical pickup device 1 to which the present invention is applied, as shown in FIG. 13, the thickness accuracy is controlled, and the ultrahigh molecular polyethylene sheets 19a and 19b cut out in a sheet shape are very Applying a sheet of acrylic double-sided tape 19d with a thickness of several tens of μm, for example, as a thin, highly compatible adhesive layer, and forming the desired protector shape from that sheet, clears the issues of molding, dimensional accuracy, and adhesiveness did. In FIG. 13, 19e indicates an ultra-high molecular weight polyethylene sheet (impermeable layer) having a function of preventing the component of the adhesive layer from leaking through the porous surface to the sheet surface, and 19f indicates a PET separator. It is.

  In the case of conventional resin molded products such as POM, a donut-shaped molded product is placed on the objective lens and UV-bonded, or in the fluorine-based coating type used for high-density recording optical disks, the mask process is applied to the coating. The above-mentioned protector member made of the ultra-high molecular polyethylene porous material is manufactured in contrast to the fact that multiple processes such as the coating process and the firing process are required and the large-scale equipment is required, so the cost is very high. The sheet material can be punched as a process, and the optical pickup apparatus as a whole contributes to the improvement of parts cost and productivity, such as simply attaching the protector to the lens holder 12 in the assembly process.

  As described above, the protector members 19a and 19b are ultra-high molecular polyethylene, and are made of a porous material having a porosity of about 20% to 40%, thereby exhibiting slidability and wear resistance. Located on both sides of the housing of the lens holder 12 in the tangential direction Tz of the first and second objective lenses 23 and 24, the optical disc 102 side from the first and second objective lenses 23 and 24 and the lens holder 12. Therefore, the lens holder 12 and the objective lenses 23 and 24 can collide with the optical disc 102 by contacting the optical disc 102 even when unnecessary vibration or the like is generated due to an impact or the like. In addition, the above-described slidability and wear resistance prevent the optical disc 102 from being scratched or worn away, which has been a problem with conventional protector members. It can be.

  The optical pickup device 1 to which the present invention is applied has light sources 21 and 22 that emit a plurality of light beams having different wavelengths, and specifications different from each other according to the formats and wavelengths used of a plurality of types of optical disks. The first and second objective lenses 23 and 24 and the first and second objective lenses 23 and 24 are attached. The focus direction F is parallel to the optical axis of the first and second objective lenses 23 and 24, and the focus. A lens holder 12 that is moved in a tracking direction T that is orthogonal to the direction F; and a support body 13 that supports the lens holder 12 so as to be movable in the focus direction F and the tracking direction T. A structure having steps 12a and 12b formed so as to be separated from the optical disc 102 on which one end side or both end sides in the radial direction R is mounted. Accordingly, the interference between the lens holder 12 and the ribs 102a and 102b existing on the inner and outer circumferences of the optical disk 102 is prevented, and the interference between the lens holder 12 and the ribs 102a and 102b of the optical disk 102 causes scratches and wear marks on the optical disk 102. Prevents from sticking. That is, the optical pickup device 1 to which the present invention is applied selectively irradiates a plurality of types of optical beams 102 with different wavelengths onto a plurality of types of optical discs 102 mounted at a common mounting position of the disc table. Avoiding the risk of interference between the lens holder 12 and the objective lenses 23 and 24 and the optical disk 102 due to a decrease in working distance, which is a concern in the optical pickup device 1 that realizes multi-wavelength compatibility, that is, such interference Thus, it is possible to prevent the optical disk 102 from being scratched or worn.

  The configuration of the optical pickup device 1 to which the present invention is applied can be applied even when only one objective lens is provided. However, the convenience of an optical system for compatibility with a plurality of types of optical disks, etc. For this reason, when two or more objective lenses are provided, the weight of the lens holder 12 is increased, and the lens holder 12 is easily affected by an impact. It is particularly effective to avoid interference by the steps 12a and 12b provided to escape in the direction. Further, the optical pickup device 1 to which the present invention is applied has two objective lenses 23 and 24 arranged side by side in the tangential direction Tz. The risk of interference with the peripheral ribs 102a and 102b can be reduced.

  Furthermore, the optical pickup device 1 to which the present invention is applied is located on both sides of the first and second objective lenses 23 and 24 in the tangential direction Tz in the housing of the lens holder 12, and the first and second objective lenses 23 and 24. With the structure having the protector members 19a and 19b having slidability and wear resistance so as to be closer to the optical disc 102 side than the objective lenses 23 and 24, the lens holder 12 and the lens holder 12 and When the objective lenses 23 and 24 and the optical disk 102 are so close that they collide, the protector members 19a and 19b come into contact with the optical disk 102, and the lens holder 12, the objective lenses 23 and 24, and the optical disk 102 collide. In addition to preventing and scratching the optical disk 102 due to the slidability and wear resistance of the protector members 19a and 19b, To prevent that with. That is, the optical pickup device 1 to which the present invention is applied is made of ultrahigh molecular polyethylene having a molecular weight of 1 million or more and a porous material having a porosity of about 20% to 40% as the protector members 19a and 19b. By constructing in this way, it exhibits slidability and wear resistance, that is, it exhibits excellent slidability due to the porosity with respect to an optical disc not provided with a hard coat such as DVD / CD. In addition, for hard optical discs that are hard-coated such as high-density recording optical discs, they exhibit wear resistance and slidability to avoid adhesion of foreign objects such as wear marks due to the protector member itself being scraped off. Thus, it is possible to solve problems such as scratching the optical disc and causing recording / reproducing errors.

  As described above, the optical pickup device 1 to which the present invention is applied has a lens holder 12 that holds the objective lenses 23 and 24, and the portion that opposes the inner and outer peripheral ribs 102a and 102b of the optical disc 102 that easily interferes. Steps 12a and 12b that escape in the separating direction are provided, and protector members 19a and 19b having slidability and wear resistance are provided in the tangential direction Tz of the objective lenses 23 and 24 provided side by side in the tangential direction Tz. This prevents the optical disk 102 from interfering with the lens holder 12 that holds the objective lenses 23 and 24 and is driven at least in the focus direction F and the tracking direction T, and the objective lenses 23 and 24 held in the lens holder 12. And prevents the optical disc 102 from being scratched or worn. Rukoto can.

  Further, as described above, the optical pickup device 1 can prevent a scratch and a wear mark from being generated on the optical disc due to interference when the optical pickup device 1 is provided in the optical disc device. Can be abolished.

  Further, as described above, the optical pickup device 1 to which the present invention is applied attaches the protector members 19a and 19b to the lens holder 12 by providing an ultra-high molecular weight polyethylene sheet cut into a sheet shape with a double-sided tape or the like. Thus, it is possible to improve the productivity by configuring the lens holder part easily and simply without requiring a complicated and elaborate manufacturing process as in the prior art, and to reduce the material cost.

  An optical disc apparatus 101 to which the present invention is applied has different wavelengths for a disc table that mounts and rotates a plurality of types of optical discs and a plurality of types of optical discs 102 that are mounted at a common mounting position of the disc table. By providing the optical pickup device 1 described above as an optical pickup device that records and / or reproduces information by selectively irradiating a plurality of light beams, the optical disc is scratched or worn by interference with the optical disc. It is possible to prevent the recording or reproduction from being defective due to the scratches or wear marks.

1 is a block circuit diagram showing a schematic configuration of an optical disc apparatus to which the present invention is applied. It is a perspective view which shows the surface side facing the optical disk of the optical pick-up apparatus to which this invention is applied. It is a perspective view which shows the surface side on the opposite side to FIG. 2 of the optical pick-up apparatus to which this invention is applied. It is a perspective view which shows the various optical components which comprise the optical pick-up apparatus to which this invention is applied, the actuator for driving an objective lens, and the actuator for driving an optical element. It is a perspective view which shows the lens holder and support body which comprise the optical pick-up apparatus to which this invention is applied. It is sectional drawing in the cross section orthogonal to the tangential direction of the lens holder which comprises the optical pick-up apparatus to which this invention is applied. It is sectional drawing in the cross section orthogonal to the tracking direction of the lens holder which comprises the optical pick-up apparatus to which this invention is applied. It is a schematic diagram which shows the state of the abrasion trace at the time of making the protector member using POM as a conventional protector member for comparing with the protector member which comprises the optical pick-up apparatus to which this invention applies collide with DVD. As compared with a protector member constituting an optical pickup device to which the present invention is applied, a protector member using a fluorine-based coating type as a conventional protector member is caused to collide with an optical disk without a hard coat. It is a schematic diagram which shows a state. It is a figure which shows the state of the material whose porosity is about 30% and an average hole diameter is about 30 micrometers as an example of the porous material used as a material of the protector member which comprises the optical pick-up apparatus to which this invention is applied, (a ) Is a schematic diagram showing a surface state, and (b) is a schematic diagram showing a cross-sectional state. It is a figure which shows the SER measurement result when the lens holder which provided the protector member using the POM as a conventional protector member compared with this invention, and the high-density recording optical disk collided, (a) is a collision It is a figure which shows the previous measurement result, (b) is a figure which shows the measurement result after making it collide by making the number of collisions into 1 time. The figure which shows the SER measurement result at the time of making the lens holder which provided the protector member which consists of a super high molecular polyethylene porous as a protector member which comprises the optical pick-up apparatus to which this invention was applied, and the high-density recording optical disk collide. is there. It is sectional drawing which shows the structure of the state formed in the sheet form with the adhesion layer of the protector member which comprises the optical pick-up apparatus to which this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Optical pick-up apparatus, 12 Lens holder, 13 Support body, 19a, 19b Protector member, 20 Pick-up base, 21 1st light source, 22 2nd light source, 23 1st objective lens, 24 2nd objective lens, 25 Beam splitter, 26 collimator lens, 27 first raising mirror, 28 second raising mirror, 30 actuator, 101 optical disk device, 102 optical disk, 103 spindle motor

Claims (7)

In an optical pickup apparatus for recording and / or reproducing information by selectively irradiating a plurality of light beams having different wavelengths to a plurality of types of optical disks mounted at a common mounting position of a disk table,
A light source that emits a plurality of light beams having different wavelengths;
First and second objective lenses having different specifications;
A lens holder to which the first and second objective lenses are attached and moved in a focus direction parallel to the optical axis of the first and second objective lenses and a tracking direction orthogonal to the focus direction;
A support portion that supports the lens holder so as to be movable in the focus direction and the tracking direction;
An optical pickup device in which the housing of the lens holder is formed with a step so that a portion on one end side or both end sides in the radial direction is separated from the mounted optical disk.   The lens holder housing is located on both sides of the first and second objective lenses in the tangential direction and is slidable so as to be closer to the optical disc side than the first and second objective lenses. 2. An optical pickup device according to claim 1, further comprising a protective means having wear resistance.   3. The optical pickup device according to claim 2, wherein the protection means is made of ultra high molecular weight polyethylene having a molecular weight of 1 million or more.   3. The optical pickup device according to claim 2, wherein the protection means is porous having a porosity of about 20% to 40%.   2. The optical pickup device according to claim 1, wherein the first and second objective lenses are arranged side by side in the tangential direction.   The light source includes an emission unit that emits a light beam having a first wavelength of about 400 to 410 nm, an emission unit that emits a light beam of a second wavelength of about 650 to 660 nm, and a wavelength of about 760 to 800 nm. The optical pickup device according to claim 1, wherein the light emitting unit that emits the light beam having the third wavelength is provided at one or a plurality of positions. A disc table that rotates by mounting multiple types of optical discs;
An optical pickup device for recording and / or reproducing information by selectively irradiating a plurality of light beams having different wavelengths to a plurality of types of optical disks mounted at a common mounting position of the disk table; In an optical disc device comprising:
A light source that emits a plurality of light beams having different wavelengths;
First and second objective lenses having different specifications;
A lens holder to which the first and second objective lenses are attached and moved in a focus direction parallel to the optical axis of the first and second objective lenses and a tracking direction orthogonal to the focus direction;
A support portion that supports the lens holder so as to be movable in the focus direction and the tracking direction;
An optical disc apparatus in which the housing of the lens holder is formed with a step so that a portion on one end side or both end sides in the radial direction is separated from the mounted optical disc.

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