JP2006344287A - Lens holder, objective lens drive unit, optical pickup, and optical recording and reproducing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens holder comprising a bonded structure which can suppress high order resonance, while preventing deterioration of aberration in an objective lens as much as possible, an objective lens drive unit equipped with the lens holder, an optical pickup, and an optical recording and reproducing apparatus. <P>SOLUTION: At a periphery of the recording medium side of a through hole 9 for mounting an objective lens formed on the lens holder 4, a plurality of first concave parts 11 recessed toward the periphery side from inner wall of the through hole 0 are formed in the circumferential direction at equal distances. A second concave part 12 recessed toward a periphery side from an inner wall of a through hole 9 with the recess smaller than the first concave parts 11 are formed between the first concave parts 11 independently from the first concave parts 11, or continuously at both sides of the first concave parts 11. Adhesive bond 13 for fixing an objective lens is applied to the areas formed at a periphery face of a fringe of the objective lens, and between the first concave parts 11 and the second concave part 12 respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens holder for holding an objective lens in an optical recording / reproducing apparatus such as a CD, DVD, MO, and MD, an objective lens driving apparatus, an optical pickup, and an optical recording / reproducing apparatus.

  In an optical pickup, laser light emitted from a semiconductor laser device is incident on an objective lens via an outward optical system equipped with a beam splitter and the like, condensed by the objective lens, and spotted on a disk as a recording medium. Irradiate. The laser light reflected from the recording surface is again passed through the objective lens and received as parallel light by the light receiver via the return optical system including the beam splitter, and the received light signal is reproduced, An error signal is generated in the focus direction and tracking direction of the laser spot. Based on the obtained error signal, a control current is supplied to the focus coil and tracking coil provided in the lens holder to control the position of the lens holder.

  The objective lens used in such an optical pickup is made of acrylic plastic because it is lightweight and suitable for high-speed driving. This objective lens is fitted into a mounting through-hole provided in the lens holder, and is attached by adhering the outer periphery with a UV curable adhesive. When mounting with such an adhesive, if the entire outer periphery of the objective lens is adhered to the lens holder, a large stress is generated in the objective lens upon shrinkage due to curing of the adhesive, causing distortion in the objective lens, Aberration deterioration occurs. Therefore, in order to relieve this stress, the adhesion of the objective lens to the lens holder is recessed from the inner wall of the through hole to the outer peripheral side, as described in Patent Document 1, for example, around the through hole on the recording medium side of the lens holder A concave portion is formed, and an adhesive is poured between the concave portion and the outer peripheral surface of the flange portion of the objective lens to be cured, thereby fixing a plurality of locations on the outer periphery of the objective lens in a spot manner.

JP-A-8-329508

  In recent years, an optical recording / reproducing apparatus requires a high-speed rotation of a disk, and therefore, the position control of the lens holder has to be performed at a high speed. As a result, the servo band of the control system extends to a high range and is 30 kHz or higher. High-order resonance at is likely to occur. When such higher-order resonance occurs, the position control of the lens holder is not stabilized.

  In the objective lens fixing structure described in Patent Document 1, an adhesive is filled in a substantially L-shaped corner formed by an outer peripheral wall of the flange portion of the objective lens and an adhesive groove provided on the recording medium side of the lens holder. It is a structure in which stress is not easily generated and the objective lens is less likely to be deteriorated by stress. However, for high-frequency resonance, the adhesive itself is fixed to the objective lens with the rigidity of the adhesive, and therefore has only a resonance suppression force up to about 30 kHz. That is, in the frequency band of 30 kHz or higher, it is equivalent to the lens holder and the objective lens being connected by a rigid spring of the adhesive itself, and is not effective in the resonance mode of 30 kHz or higher. For this reason, it is difficult to suppress the resonance peak at 30 kHz or more, and there is a problem that it is difficult to cope with high-speed rotation of the recording medium.

  In view of the above problems, the present invention provides a lens holder having an adhesive structure capable of suppressing higher-order resonance while preventing aberration deterioration in the objective lens as much as possible, and an optical pickup and optical recording / reproducing apparatus including the lens holder. The purpose is to provide.

The lens holder of the present invention is a lens holder for an objective lens provided in an optical pickup,
A plurality of first recesses that are recessed from the inner wall of the through hole to the outer peripheral side are formed in the peripheral portion on the recording medium side of the through hole for attaching the objective lens formed in the lens holder, and the first Forming a second recess having a recess from the inner wall of the through hole to the outer peripheral side smaller than the first recess, independently of the first recess,
An adhesive for fixing the objective lens is applied to a region formed between the outer peripheral surface of the flange portion of the objective lens that fits into the through hole and the first concave portion and the second concave portion, respectively.

The lens holder of the present invention is a lens holder for an objective lens provided in an optical pickup,
A plurality of first concave portions recessed from the inner wall of the through hole to the outer peripheral side are formed in the peripheral portion on the recording medium side of the through hole for attaching the objective lens formed in the lens holder. The second recess is smaller than the first recess, the recess from the inner wall of the through hole to the outer peripheral side being continuous on both sides of the first recess;
An adhesive for fixing the objective lens is applied to a region formed between the outer peripheral surface of the flange portion of the objective lens that fits into the through hole and the first concave portion and the second concave portion.

In the lens holder of the present invention, an inner peripheral side end of the first recess is recessed outward to form a third recess, and the third recess and the outer peripheral surface of the flange of the objective lens It is characterized by having an adhesive in between.

The lens holder of the present invention is characterized in that the first and second concave portions are formed to be inclined from the outer peripheral side to the inner peripheral side.

  The objective lens driving device, the optical pickup and the optical recording / reproducing device of the present invention are characterized by having the lens holder.

  According to the present invention, resonance up to around 30 kHz can be suppressed by the fixing structure with the adhesive filled in the relatively wide first recess. In addition, due to the structure in which the lens holder is fixed by the adhesive filled in the second recess, the adhesive is subjected to a shear mode in a narrow gap with respect to resonance at a high frequency of about 50 to 60 kHz, for example. Since the objective lens is firmly fixed to the lens holder regardless of the rigidity (storage elastic modulus) of the adhesive itself, the resonance in the high frequency band can be suppressed. For this reason, it is possible to suppress resonance over a wide band, stabilize the position control of the lens holder, and provide a lens holder, an objective lens driving device, an optical pickup, and an optical recording / reproducing device that can cope with high-speed rotation of the disc. it can.

  Also, if the objective lens collar and the lens holder are bonded to the entire circumference of the objective lens, there is a risk of delamination due to the shrinkage caused by the curing of the adhesive, and a large stress is generated on the objective lens. However, although aberration deterioration occurs, in the present invention, partial adhesion with an adhesive is performed, so that peeling and aberration deterioration can be prevented.

  Moreover, if it dents on the both sides of each 1st recessed part from the inner wall of the said through-hole to the outer peripheral side, and the dent forms the 2nd recessed part smaller than the said 1st recessed part, it will flow from a wide 1st recessed part. Since the adhesive also flows into the second recess at the same time, the work of pouring the adhesive into the second recess having a narrow width in addition to the first recess becomes unnecessary. The effect of improving workability can be obtained.

  Further, the inner peripheral end of the first concave portion is recessed outward to form a third concave portion, and an adhesive is also applied between the third concave portion and the outer peripheral surface of the flange portion of the objective lens. For example, a shear mode adhesive portion is formed in the first concave portion, and resonance at a high frequency is better suppressed.

  Further, by forming the second concave portion on the inclined surface with the inner wall side lowered, the injection of the adhesive into the region between the concave portion and the collar portion can be easily and reliably performed.

  FIG. 1 is a perspective view of an objective lens driving device of an optical pickup showing an embodiment of a lens holder of the present invention. This optical pickup is attached to a movable base (not shown) whose position is controlled in the radial direction of a rotating recording medium (disk) of the optical recording / reproducing apparatus. Reference numeral 1 denotes a base fixed to the movable table. A U-shaped yoke 2 is fixed to the movable base. Reference numeral 3 denotes a permanent magnet fixed to the opposing surface of the yoke 2. Reference numeral 4 denotes a lens holder mounted between the permanent magnets 3, 3. Reference numeral 5 denotes an objective lens fixed to the lens holder 4 by means described later. The lens holder 4 is supported on the base 1 by being floated at a position between the permanent magnets 3 and 3 by a plurality of elastic wires 6 on the left and right sides. On the surface of the lens holder 4 facing the permanent magnets 3 and 3, a tracking coil 7 made of a printed coil or the like is fixed at the center, and focus coils 8 are fixed on both sides thereof.

  2 is a perspective view showing a configuration of a main part of the lens holder 4, FIG. 3 is a partially enlarged view thereof, FIG. 4 is a plan view thereof, and FIG. 5 is a partial sectional view thereof. As shown in FIG. 2, the lens holder 4 is light and high strength made of resin such as liquid crystal polymer to which a reinforcing material is added, and has a through hole 9 for attaching the objective lens 5. On the inner peripheral surface of the through hole 9, a protrusion 10 that receives the bottom surface of the flange 5a of the objective lens 5 (the surface on the opposite side of the recording medium) is formed over the entire periphery.

  Two concave portions 11 (first concave portions) that are recessed from the inner wall of the through hole 9 toward the outer peripheral side in the periphery of the through hole 9 of the objective lens 5 on the recording medium side are shown in the X direction ( The tangential direction of the recording medium is formed to face each other. As shown in FIG. 5, the bottom surface 11a is preferably formed on an inclined surface whose inner peripheral side is lowered. Continuing on both sides of each first recess 11 is recessed from the inner wall of the through hole 9 to the outer peripheral side, and the first recess 11 has a recess width b smaller than the width a of the first recess 11 (a> b ) The second recess 12 is formed. In order to secure adhesive strength and prevent aberration deterioration, the preferred width a of the first recess 11 is 0.5 to 1 mm, and the depth c on the inner peripheral side is 0.1 to 0.4 mm. From the same viewpoint, the preferred width b of the second recess 12 is 0.01 to 0.1 mm, and the depth d is 0.1 to 0.4 mm.

  In FIG. 4, the preferred formation angle range α of the first concave portion 11 (the same applies to the third concave portion 14) is 30 to 90 degrees in view of the adhesive strength in order to secure the adhesive strength and prevent the deterioration of aberration. It is. From the same viewpoint, the preferable formation angle range β of the second recess 12 is 5 to 25 degrees. From the same viewpoint, the preferable angle γ formed by the line connecting the tip of the second recess 12 and the lens center with respect to the X axis is 20 to 70 degrees.

  In the present embodiment, the third recess 14 is formed by recessing the inner peripheral side of the first recess 11 outward. In this embodiment, the width e of the third recess 14 is formed to be approximately equal to the width b of the second recess 12, but these may be formed to have different widths. Further, the circumferential width of the objective lens of the third recess 14 is formed substantially equal to the circumferential width of the inner side of the first recess 11. Further, the depth f of the third recess 14 is set to a depth g or less (f ≦ g) from the inner peripheral side end of the first recess 11 to the protrusion 10. The preferred width e of the third recess 14 is 0.01 to 0.1 mm, and the depth f on the inner peripheral side is 0.1 to 0.4 mm.

  As shown in FIGS. 6 and 7, the objective lens 5 is attached by fitting the flange portion 5 a into the through hole 9 and bringing the bottom surface of the flange portion 5 a into contact with the protrusion 10. Then, an adhesive 13 for fixing the objective lens is applied to a region formed between the outer peripheral surface of the flange portion 5 a of the objective lens 5 and the first concave portion 11 and the second concave portion 12.

  Here, as the adhesive 13 filling the recesses 11 and 12, for example, an acrylic UV curable resin can be used, and by injecting the fluid adhesive into the wide first recess 11 by an injector, The second recess 12 can also be filled by flowing. After injecting the adhesive 13 in a fluid state in this way, the objective lens 5 is fixed to the lens holder 4 by UV curing.

  FIG. 8 shows the result of examining the resonance amplitude when vibration is applied to the objective lens in order to investigate the resonance suppression effect in the objective lens mounting structure of the present embodiment. The sample (example) used for the measurement has a diameter of the objective lens 5 of 4 mm, the width a of the first recess 11 is 0.75 mm, the depth c is 0.2 mm, and the width of the second recess 12. b was 0.05 mm, the depth d was 0.15 mm, the width e of the third recess 14 was 0.05 mm, and the depth f was 0.2 mm. Further, the formation angle range α of the first recess 11 and the third recess 14 is 30 degrees, and the formation angle range β of the second recess 12 is 15 degrees (therefore, the tip of the second recess 12 is X The angle γ made with respect to the axis was 45 degrees). As a comparative example, the one having only the first recess 11 in the above embodiment was used. The measurement is performed by passing a current having a frequency in the drive coil (frequency corresponding to the horizontal axis of the graph of FIG. 8) and measuring the vibration amplitude generated in the lens portion by using a laser Doppler vibrometer. It was.

  As shown in FIG. 8, according to the embodiment, resonance at 51 kHz shown in P <b> 1 (a mode in which points A and B move like a seesaw in the front and back direction of the paper surface around the X axis in FIG. 4), It can be seen that the resonance at 57 kHz (the mode in which the points C and D move like a seesaw in the front and back direction of the paper surface around the Y axis in FIG. 4) can be suppressed.

  As described above, the lens holder 4 of the present invention is provided with the narrow second concave portion 12 in addition to the wide first concave portion 11 in the inner and outer directions, and the adhesive 13 is applied to each. Due to the structure in which the lens holder 4 is fixed to the objective lens 5 by the adhesive 13 filled in the second recess 12, the adhesive is sheared in a narrow gap with respect to resonance at a high frequency of, for example, about 50 kHz or more. Since the objective lens 5 is firmly fixed to the lens holder 4 regardless of the rigidity of the adhesive itself, resonance in a high frequency band can be suppressed. For this reason, it is possible to suppress resonance over a wide band, stabilize the position control of the lens holder, and provide a lens holder, an objective lens driving device, an optical pickup, and an optical recording / reproducing device that can cope with high-speed rotation of the disc. it can.

  Further, in the present embodiment, the inner end of the first recess 11 is recessed outward to form the third recess 14, and the third recess 14 and the flange 5 a of the objective lens 5 are formed. Since the adhesive 13 is also applied between the outer peripheral surfaces of the first and second outer peripheral surfaces, a shear mode adhesive portion is formed in the first concave portion 11, and resonance at a high frequency is better suppressed.

  Further, if the flange portion 5a of the objective lens 5 and the lens holder 4 are bonded over the entire circumference of the objective lens 5, there is a risk of peeling due to shrinkage caused by the curing of the adhesive. However, in the present invention, since partial bonding is performed in the circumferential direction by the adhesive 13, peeling and aberration deterioration can be prevented.

  Further, in the present embodiment, the second recesses 12 are formed on both sides of each first recess 11 from the inner wall of the through hole 9 to the outer periphery, and the recess is smaller than the first recess 11. Therefore, since the adhesive automatically flows into the second recess 12 by injecting the fluidized adhesive 13 from the wide first recess 11, the adhesive is applied to the narrow second recess 12. The operation | work which inject | pours becomes unnecessary and the effect that workability | operativity improves in addition to the said effect is acquired.

  9 and 10 are plan views respectively showing other embodiments of the lens holder according to the present invention. In the embodiment of FIG. 9, the second concave portion 12 </ b> A is formed independently of the first concave portion 11 so as to face the Y-axis direction. In the embodiment of FIG. 10, three first recesses 11 and three second recesses 12 are provided independently. 9 and 10 can also suppress the resonance at the high frequency. Four first concave portions 11 and four second concave portions 12 may be provided, and a configuration in which three or four first concave portions 11 are provided on both sides of the first concave portion 11 is also possible. It may be adopted.

  FIG. 11 is a sectional view showing another embodiment of the lens holder according to the present invention. In this embodiment, the second recess 12A is formed to be inclined from the outer peripheral side to the inner peripheral side. According to the embodiment of FIG. 11, the injection of the adhesive by the injector into the region between the second recess 12A and the outer peripheral surface of the flange 5a can be performed easily and reliably.

  FIG. 12 is a block diagram showing an embodiment of an optical recording / reproducing apparatus according to the present invention constituted by using the optical pickup actuator. In FIG. 12, reference numeral 51 denotes a recording medium (optical disk) made of an optical recording medium or a magneto-optical recording medium, and this recording medium 51 is rotated by a spindle motor 52. An optical pickup 53 performs recording and reproduction by irradiating the recording medium 51 with laser light through the objective lens 5. The optical pickup 53 is mounted with the optical pickup actuator that causes the objective lens 5 to follow the surface shake and track shake of the recording medium 51. The movable base constituting the optical pickup 53 is driven in the radial direction of the recording medium 51 by a coarse motor 54. The electrical signal photoelectrically converted by the optical pickup 53 is arithmetically processed by the signal processing system 55, and the tracking error signal, focus error signal, reproduction signal, etc. obtained by the arithmetic processing are input to the drive controller 59 that controls the entire apparatus. The An optical pickup control system 56 controls the output of the laser beam from the optical pickup 53, the emission pulse, and the operation of the optical pickup actuator based on the error signal. 57 is a drive control system for the spindle motor 52, and 58 is a drive control system for the coarse motion motor 54. Reference numeral 60 denotes an interface for exchanging signals with the outside. This optical recording / reproducing apparatus is incorporated in a cabinet.

  FIG. 13 is a block diagram showing an embodiment of an optical pickup 53 using the optical pickup actuator according to the present invention. In FIG. 13, 61 is a light source composed of a laser unit, 62 is a diffractive element that splits the laser light from the light source 61 into a plurality of beams, 63 is a collimator lens that collimates the laser light emitted from the diffractive element 62, and 64 is The beam splitter 64 condenses the light from the collimator lens 63 by the objective lens 5 and transmits it to the recording medium (optical disc) 51 side, and reflects the reflected light transmitted from the recording medium 51 through the objective lens 5. Reflected to the detector 66 side. Reference numeral 68 denotes an anamorphic lens that converges the reflected light from the beam splitter 64 on the detector 66. The anamorphic lens 68 is a compound lens having a cylindrical surface on the incident side and a concave surface on the output side. The concave surface optimizes the magnification of the return optical system and moves the anamorphic lens 68 in a direction along the optical axis. Thus, the information light is provided for the purpose of being adjustable so as to be focused at an appropriate size on the light receiving surface inside the detector 66.

  When transmitting through the cylindrical surface of the anamorphic lens 68, the information light generates astigmatism, and this astigmatism is used to detect a focus error. This focus error detection method is called an astigmatism method. The tracking error signal is obtained from a method of obtaining a difference signal between two sub beams obtained by passing the laser light emitted from the light source 61 through the diffraction element 62 or a difference signal including the main beam. In the present invention, the tracking error signal may be obtained by a push-pull method, a wobbling method, or a heterodyne method. As a method for generating a focus error signal, a knife edge method, a Foucault method, or a critical angle method can be applied.

It is a perspective view which shows an example of the lens holder drive device which shows one Embodiment of the lens holder by this invention. It is a perspective view which shows the principal part of the lens holder of this Embodiment. It is a partial expansion perspective view of the lens holder of this Embodiment. It is a top view of the lens holder of this Embodiment. It is a fragmentary sectional view of the lens holder of this Embodiment. It is sectional drawing which shows the filling structure of the adhesive agent in the 1st recessed part of this Embodiment. It is sectional drawing which shows the filling structure of the adhesive agent in the 2nd recessed part of this Embodiment. It is a figure which shows the test result regarding the resonance suppression in this Embodiment. It is a top view which shows other embodiment of the lens holder by this invention. It is a top view which shows other embodiment of the lens holder by this invention. It is sectional drawing which shows other embodiment of the lens holder by this invention. It is a block diagram which shows one Embodiment of the optical recording / reproducing apparatus of this invention. It is a block diagram which shows one Embodiment of the optical pick-up of this invention.

Explanation of symbols

1: base, 2: yoke, 3: permanent magnet, 4: lens holder, 5: objective lens, 5a: collar, 6: wire, 7: tracking coil, 8: focus coil, 9: through hole, 10: protrusion 11, 11: first recess, 12, 12A: second recess, 13: adhesive, 14: third recess, 51: recording medium, 52: spindle motor, 53: optical pickup, 54: coarse motion motor 55: signal processing system, 56: optical pickup control system, 57: spindle motor drive control system, 58: coarse motor drive control system, 59: drive controller, 60: interface, 61: light source, 62: diffraction element 63: collimator lens, 64: beam splitter, 66: detector, 68: anamorphic lens

Claims (7)

A lens holder for an objective lens provided in an optical pickup,
A plurality of first recesses that are recessed from the inner wall of the through hole to the outer peripheral side are formed in the peripheral portion on the recording medium side of the through hole for attaching the objective lens formed in the lens holder, and the first A second recess having a recess from the inner wall of the through hole to the outer peripheral side is smaller than the first recess, independent of the first recess,
An objective lens fixing adhesive is applied to regions formed between the outer peripheral surface of the flange portion of the objective lens that fits into the through hole and the first concave portion and the second concave portion, respectively. holder. A lens holder for an objective lens provided in an optical pickup,
A plurality of first concave portions recessed from the inner wall of the through hole to the outer peripheral side are formed in the peripheral portion on the recording medium side of the through hole for attaching the objective lens formed in the lens holder. The second recess is smaller than the first recess, the recess from the inner wall of the through hole to the outer peripheral side being continuous on both sides of the first recess;
An objective lens fixing adhesive is applied to a region formed between the outer peripheral surface of the flange portion of the objective lens that fits into the through hole and the first concave portion and the second concave portion. . The lens holder according to claim 1 or 2,
An inner peripheral side end of the first recess is recessed outward to form a third recess, and an adhesive is also applied between the third recess and the outer peripheral surface of the flange of the objective lens. A lens holder characterized by. In the lens holder in any one of Claim 1 to 3,
The lens holder, wherein the second concave portion is formed to be inclined from the outer peripheral side to the inner peripheral side. An objective lens driving device comprising the lens holder according to claim 1. An optical pickup comprising the objective lens driving device according to claim 5. An optical recording / reproducing apparatus comprising the optical pickup according to claim 6.

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