JP2009087382A - Optical pickup, and optical disk drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens drive device which is more compact than that by conventional technology and which has a wide correction range, a spherical aberration correcting device using the lens drive device, and an optical pickup device using the spherical aberration correcting device. <P>SOLUTION: The optical pickup is provided with a supporting mechanism supporting movably a lens holder in the direction of optical axis direction of a spherical aberration correcting lens, while the supporting mechanism is provided with a guide rail and a guide part sliding the holder along the guide rail. When the spherical aberration correcting lens is approached most to a rising mirror in a range in which the spherical aberration correcting lens is operated, an end part of the guide rail is arranged at the side of a rising mirror reflection plane so that the guide part is set to the side of the rising mirror reflection plane. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a spherical aberration correcting unit using a lens driving device that enables a lens constituting an optical pickup device to move in the optical axis direction, and an optical pickup device using the spherical aberration correcting unit.

  In recent years, in the field of recording or reproducing information signals using an optical disc as an information recording medium, development of a small and large-capacity optical disc apparatus has been advanced in order to handle high-definition still images and moving images.

  The optical disc apparatus includes an optical pickup for forming a beam spot on the information recording surface of the optical disc. In this optical pickup, the light beam emitted from the light source generates spherical aberration when passing through a transparent protective substrate layer that protects the information recording layer.

  In Patent Document 1, in order to correct this spherical aberration, a lens group for correcting spherical aberration is provided, and a variable air gap is formed between the surfaces of a pair of sequential lens elements in the lens group, thereby mechanically. An apparatus for changing the gap interval by a technique is disclosed.

  6 is an example in which the conventional lens driving device in Patent Document 1 is applied to an optical pickup. FIG. 6A is a plan view of the optical pickup, and FIG. 6B is a side view of the optical pickup.

  In the figure, 14 is an optical disk, 1 is a laser diode as a light source, 2 is a collimating lens, 3 is a beam splitter, 4 is a raising mirror, 5 is an objective lens, 6 is a detection lens, 7 is a photoelectric conversion element, and the like. It is a photodetector.

  When performing recording / reproduction with respect to the optical disc 14, the light beam emitted from the laser diode 1 passes through the beam splitter 3 and the collimating lens 2, and is deflected toward the optical disc 14 by the rising mirror 4, The light is focused on the optical disk 14 by the objective lens 5 as a light spot. The reflected beam from the optical disk 14 passes through the objective lens 5, is deflected by the rising mirror 4, passes through the collimator lens 2, is deflected by the beam splitter 3, and is detected by the detection lens 6 of the detector 7. It is condensed on the light receiving surface.

  The collimating lens 2 is held by a lens holder 8, and the lens holder 8 is supported by a pair of guide shafts 9 and a sliding shaft 10. The guide shaft 9 is held by a shaft holder 13, the sliding shaft 10 is fixed to the lens holder 8, and the guide shaft 9 and the sliding shaft with respect to the optical axis of the collimating lens 2. The ten axial directions are arranged in parallel.

When the collimating lens 2 is moved in the optical axis direction in order to correct the spherical aberration, the sliding shaft 10 is moved to a bearing hole portion in the shaft holder 13 by driving means such as a gear or a stepping motor (not shown). Against the thrust direction.
JP 2004-77705 A

  Although the spherical aberration correction of the optical pickup device can be performed by the conventional technique, in recent years, in order to realize a high density of the optical information recording medium, a multilayer optical information recording medium having a plurality of information recording layers has been developed. There is a need to make a larger spherical aberration correction. In addition, the optical system configuration becomes more complicated and the number of parts is increased in order to cope with recording and reproduction of a plurality of types of optical information recording media, while the optical pickup itself is required to be smaller and narrower. There is a need to configure an optical pickup so that spherical aberration correction can be performed in the component placement space. Furthermore, multilayer recording disks having various protective layer thicknesses have been proposed as next-generation technologies, and a spherical aberration correction mechanism with a wider correction range is being demanded of optical pickups.

  The present invention provides a lens driving device that is smaller than the prior art and has a wide correction range, a spherical aberration correcting device using the lens driving device, and an optical pickup device using the spherical aberration correcting device. For the purpose.

  In order to solve the above-described problems and achieve the object, an optical pickup according to claim 1 includes an objective lens that condenses light emitted from a light source on an information recording surface of an information recording medium, and the information recording by the objective lens. A spherical aberration correction lens that corrects the spherical aberration of the light beam focused on the surface, a lens holder that holds the spherical aberration correction lens, and the lens holder that is movable in the optical axis direction of the spherical aberration correction lens A support mechanism that moves the lens holder in the optical axis direction of the spherical aberration correction lens, and deflects the emitted light that has passed through the spherical aberration correction lens at a substantially right angle and guides it to the incident surface of the objective lens. An optical pickup including a rising mirror, wherein the support mechanism includes a guide rail and a guide portion that slides along the guide rail, and the spherical aberration correction When the spherical aberration correction lens is closest to the rising mirror, the end portion of the guide rail is raised so that the guide portion fits on the side surface of the rising mirror reflecting surface. An optical pickup arranged on a side surface of a mirror reflection surface.

  Accordingly, there are provided a lens driving device that is smaller than the conventional technology and has a wide correction range, a spherical aberration correcting device using the lens driving device, and an optical pickup device using the spherical aberration correcting device. Is possible.

  According to the present invention, a lens driving device that is smaller than the conventional technique and has a wide correction range, a spherical aberration correction device using the lens driving device, and an optical pickup device using the spherical aberration correction device, It is possible to provide an optical disc drive provided with the optical pickup device and an optical information device provided with the optical disc drive.

  Hereinafter, an optical pickup according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
1A and 1B are diagrams for explaining an optical pickup according to a first embodiment of the present invention. FIG. 1A is a plan view of the optical pickup, and FIG. 1B is a side view of the optical pickup.

  In the figure, 14 is an optical disk, 1 is a laser diode as a light source, 2 is a collimating lens, 3 is a beam splitter, 4 is a raising mirror, 5 is an objective lens, 6 is a detection lens, 7 is a photoelectric conversion element, and the like. It is a photodetector.

  When performing recording / reproduction with respect to the optical disc 14, the light beam emitted from the laser diode 1 passes through the beam splitter 3 and the collimating lens 2, and is deflected toward the optical disc 14 by the rising mirror 4, The light is focused on the optical disk 14 by the objective lens 5 as a light spot. As a result, information is recorded on the information recording surface of the optical disc 14 or information recorded on the information recording surface of the optical disc 14 is read.

  Further, the reflected beam from the optical disk 14 passes through the objective lens 5, is deflected by the rising mirror 4, passes through the collimator lens 2, is deflected by the beam splitter 3, and is detected by the detection lens 6. 7 is collected on the light receiving surface, and information from the information recording surface is converted into an electric signal.

  In the optical pickup shown in the figure, by collimating or diverging a parallel light beam incident on the objective lens 5 by the movement of the mate lens 2, a difference in the protective layer thickness of the optical disk 14 or spherical aberration of the optical pickup is achieved. The spherical aberration at the spot position due to the above is adjusted so as to be less than the allowable value.

  The lens holder 8 that holds the collimating lens 2 is supported by a first guide shaft 11 and a second guide shaft 12, each of which is a guide shaft that guides the movement of the lens holder 8. It has become.

  Both ends of the first guide shaft and the second guide shaft 6 are fixed to a shaft holder 13, and each guide shaft has an axial direction parallel to the optical axis of the collimator lens 2. It is arranged to be.

  In order to keep the collimating lens 2 from tilting in the optical axis direction small, it is necessary to increase the length of the receiving portion of the guide shaft. For this purpose, the guide portion 15 is provided. There is a drawback in that it interferes with a portion near the collimator and narrows the movable range of the collimating lens 2. Therefore, in FIG. 1, unlike the conventional example, the first guide is arranged so that the guide portion 11 is placed on the side surface of the rising mirror 4 when the collimating lens 2 is closest to the rising mirror 4 side. One end of the shaft 6 is arranged on the side surface of the rising mirror 4.

  Further, the surface of the lens holder 8 on the beam splitter 3 side has a substantially planar structure that does not protrude, and the movable range is maximized even when the collimating lens moves away from the rising mirror. It has become.

  FIG. 2 is a plan view specifically showing the positional relationship of the lens holder 8 when the collimating lens is moved, and FIG. 2B shows a state in which the collimating lens 2 is at a substantially central position. FIG. 2A and FIG. 2C show a state where the collimating lens 2 is shifted to the right side and the left side, respectively. Compared with the conventional example, it can be seen that the movable range of the collimating lens 2 is large, and that larger spherical aberration correction is possible even in a small space.

  As described above, in the present embodiment, the amount of movement of the collimating lens can be increased, and therefore, when compared in the same space as the conventional example, the spherical aberration correction amount can be increased.

  Although not shown in the present embodiment, a DC motor, a stepping motor or the like is generally provided as a driving force generation source for moving the collimating lens 2, but an ultrasonic motor is driven. When used as a power generation source, a smaller and simpler configuration is possible.

  In this embodiment, spherical aberration correction is performed with one (group 1) collimating lens, but spherical aberration correction may be performed with a beam expander including two or more lenses (group 2). Is the same. In this case, the spherical aberration is adjusted by converging or diverging the light flux by changing the distance between at least one pair of lenses constituting the beam expander.

  Furthermore, if the optical pickup in the present embodiment is applied to a double-layer disc or a future multi-layer disc having three or more layers, the optical pickup can be made compact.

  In the present embodiment, the guide portion is provided on the lens holder side and the guide shaft is slid. However, the guide shaft may be joined to the lens holder side and the guide shaft may be slid on the guide groove.

(Embodiment 2)
FIG. 3 is a diagram schematically showing a collimating lens and a lens holder applicable to the optical pickup according to Embodiment 2 of the present invention.

  This figure is a view of the lens holder and the collimating lens viewed from the optical axis direction. FIG. 3A shows a lens holder and a collimating lens when the lens surface of the collimating lens is circular, and this is the shape in the conventional example.

  In the figure, when the lateral direction corresponds to the tracking direction, the optically necessary effective diameter of the collimating lens may be smaller in the radial direction than in the tracking direction. This is because it is not necessary to consider the movement of the objective lens in the tracking direction (lens shift) during tracking control.

  Accordingly, a part of the collimating lens and the lens holder in the vertical direction can be cut as shown in FIG. 3B, thereby reducing the overall height of the optical pickup. It can be configured.

  The cut amount is, for example, the length of the operating range of the lens shift in the radial direction of the objective lens. Further, the lens shape may be elliptical.

  FIG. 3 shows an example of a collimating lens, but when the spherical aberration correction lens is a beam expander, if the shape of the beam expander lens is made the same, the overall height of the optical pickup can be reduced, A thin optical pickup can be configured.

(Embodiment 3)
FIG. 4 is a diagram schematically showing a collimator lens applicable to the optical pickup according to Embodiment 3 of the present invention. In FIG. 4, diffractive optics for correcting chromatic aberration is provided on the incident surface or the exit surface of the collimator lens. Element 22 is formed.

  The diffractive optical element 22 may be integrally formed with the collimating lens, or a diffractive optical element 22 of a different material may be attached to the collimating lens surface. The diffractive optical element 22 may be formed on both the incident surface and the exit surface.

  As a result, it is possible to satisfactorily secure the light collection characteristics of the objective lens even when the light source has a wavelength variation or the light source wavelength has a spread.

(Embodiment 4)
FIG. 5 is a diagram showing a configuration of an optical disk drive for explaining an application example of the optical pickup shown in FIG. 1, wherein 16 is an optical pickup unit having the configuration shown in FIG. A pickup movement drive mechanism 21 including a seek motor 18, a lead screw 19, a guide rail 20, and the like that are moved in the radial direction of the optical disk 40 is a spindle motor that rotationally drives the optical disk 40. By moving the optical pickup 16 in the seek direction, Information is read from and recorded on the optical disk 14.

  If the optical disk drive shown in FIG. 1 is applied to an optical information device, a small and high-performance optical information device can be realized.

  The optical pickup and the optical information recording / reproducing apparatus of the present invention are useful for an optical information recording / reproducing apparatus using an optical disk such as a magneto-optical recording apparatus or a CD, DVD, HD-DVD, Blu-ray disk apparatus. It can also be applied to optical systems and devices of hologram recording devices and future ultra-high density recording / reproducing devices.

FIG. 1 is a schematic diagram showing the structure of an optical pickup according to the first embodiment of the present invention. The figure for demonstrating operation | movement of the optical pick-up shown in FIG. Schematic which shows the collimating lens and lens holder which can be applied to the optical pick-up concerning the 2nd Embodiment of this invention. Schematic which shows the collimating lens and lens holder which can be applied to the optical pick-up concerning the 3rd Embodiment of this invention. Schematic showing the structure of an optical disc drive according to a fourth embodiment of the present invention Schematic showing the structure of a conventional optical pickup shown in Patent Document 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser diode 2 Collimating lens 3 Beam splitter 4 Rising mirror 5 Objective lens 6 Detection lens 7 Photo detector 8 Lens holder 9 Guide shaft 10 Sliding shaft 11 First guide shaft 12 Second guide shaft 13 Axis holder 14 Optical disk 15 Guide unit 16 Optical pickup unit 17 Pickup movement drive mechanism 18 Seek motor 19 Lead screw 20 Guide rail 21 Spindle motor 22 Diffractive optical element

Claims (13)

An objective lens for condensing the light emitted from the light source on the information recording surface of the information recording medium;
A spherical aberration correction lens for correcting the spherical aberration of the light beam condensed on the information recording surface by the objective lens;
A lens holder for holding the spherical aberration correction lens;
A support mechanism for supporting the lens holder movably in the optical axis direction of the spherical aberration correction lens;
Driving means for moving the lens holder in the optical axis direction of the spherical aberration correction lens;
An optical pickup comprising a rising mirror that deflects the emitted light that has passed through the spherical aberration correction lens at a substantially right angle and guides it to the incident surface of the objective lens;
The support mechanism includes a guide rail,
A guide portion that slides along the guide rail,
In the range in which the spherical aberration correction lens operates, when the spherical aberration correction lens is closest to the rising mirror, the end portion of the guide rail is arranged so that the guide portion fits on the side surface of the rising mirror reflecting surface. Is arranged on a side surface of the rising mirror reflecting surface. The support mechanism includes at least one guide groove extending in parallel with the optical axis direction of the spherical aberration correction lens from the side of the rising mirror, and an axis that slides on the guide groove and is joined to the lens holder. The optical pickup according to claim 1. The optical pickup according to claim 1, wherein the spherical aberration correction lens is a collimating lens that converts the emitted light from the light source into parallel light. The optical pickup according to claim 1, wherein the spherical aberration correction lens is a beam expander that converts a beam diameter of the emitted light from the light source. The optical pickup according to claim 3, wherein the collimating lens is provided with a color correction element. 4. The optical pickup according to claim 3, wherein the collimating lens has a shape cut in a height direction. The optical pickup according to claim 4, wherein the beam expander is provided with a color correction element. The optical pickup according to claim 4, wherein the beam expander has a shape cut in a height direction. 9. The optical pickup according to claim 1, wherein the driving unit is a stepping motor. The optical pickup according to claim 1, wherein the driving unit is an ultrasonic motor. The optical pickup according to any one of claims 1 to 10, wherein the information recording medium includes two or more information recording layers. An optical disc drive apparatus comprising the optical pickup according to any one of claims 1 to 11. An optical information device comprising the optical disk drive according to claim 12.

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