JP2004055071A - Optical pickup device, method of manufacturing optical pickup device, and recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it adaptable to an optical disk in which the recording density of information signals is higher than before by easily securing sufficient accuracy for the attaching position of an optical element together with shortening of the emitted light wavelength of a light source and increase of the numerical aperture of an objective lens. <P>SOLUTION: The relative positions of a concave lens 13 and a convex lens 14 constituting a beam expander are adjusted in two directions orthogonal to an optical axis. Thus, an aberration generated due to the attaching error of the other optical element is corrected. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical pickup device for writing or reading an information signal to or from an optical recording medium, a method for manufacturing such an optical pickup device, and recording or reproducing an information signal using the optical recording medium provided with the optical pickup device. The present invention relates to a recording / reproducing apparatus for performing the above.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an optical pickup device for writing or reading an information signal on or from an optical recording medium such as an optical disk has been proposed. In addition, the optical pickup device includes such an optical pickup device and records or reproduces an information signal using the optical recording medium. A recording / reproducing device has been proposed. Such an optical pickup device can cope with an optical disk having a higher information signal recording density than before by shortening the oscillation wavelength of a semiconductor laser serving as a light source and increasing the numerical aperture (NA) of an objective lens. It has been demanded.
[0003]
In an optical pickup device (optical pickup device for a high-density phase change optical disk) corresponding to such an optical disk having a high recording density, as shown in FIG. In addition, there has been proposed an optical disk having a beam expander for correcting a spherical aberration generated in a transparent cover layer 109a formed on a signal recording surface of an optical disk 109. Note that this spherical aberration is caused by an error in the thickness of the transparent cover layer 109a depending on the location.
[0004]
In such an optical pickup device, the optical elements constituting the optical system of the optical pickup device include a semiconductor laser 101, a beam splitter 104, and photodetectors 110 and 112 disposed in a fixed optical block 115. Only the optical components such as the objective lens 108 and the rising mirror 107 are disposed in the movable optical block 116.
[0005]
That is, in this optical pickup device, in the fixed optical block 115, the light beam emitted from the semiconductor laser 101 is converted into a parallel light beam by the collimator lens 102, and further, isotropic light amount distribution (by the anamorphic prism 103). After being shaped into a light beam having a light beam cross-sectional intensity distribution), the light beam enters a beam splitter 104 via a grating 113 for splitting the light beam for tracking servo.
[0006]
The light beam reflected by the beam splitter 104 is received by the photodetector 110. In the optical pickup device, the light emission output of the semiconductor laser 101 is feedback-controlled based on the output of the photodetector 110, so that the light emission amount of the semiconductor laser 101 is kept constant.
[0007]
The light beam transmitted through the beam splitter 104 is emitted from the fixed optical block 115. The light beam emitted from the fixed optical block 115 enters the movable optical block 116, passes through the spherical aberration correcting beam expander including the concave lens 105 and the convex lens 106 in the movable optical block 116, The light is deflected in a direction perpendicular to the optical disk 109, and is incident on an objective lens 108 via a λ / 4 (quarter wavelength) plate 114 for changing a light beam into circularly polarized light. The light beam incident on the objective lens 108 is condensed by the objective lens 108 on the signal recording surface of the optical disk 109 as a minute light spot.
[0008]
The light beam reflected on the signal recording surface of the optical disk 109 passes through the objective lens 108 again, passes through the λ / 4 plate 114, is deflected by the rising mirror 107, passes through the convex lens 106 and the concave lens 105 of the beam expander, and moves. The light is emitted from the optical block 116 and enters the fixed optical block 115.
[0009]
In the fixed optical block 115, the return light from the optical disk 109 returns to the beam splitter 104. In the beam splitter 104, the return light from the optical disk 109 is reflected and deflected, and is condensed by the condenser lens 111 on the light receiving surface of the photodetector 112.
[0010]
In this optical pickup device, only the movable optical block 116 is moved in the tracking direction, which is the radial direction of the optical disc 109, as shown by the arrow T in FIG. Just fine. Therefore, in this optical pickup device, the movable optical block 116 can be started and stopped at a high speed, and the access time to the target information track can be shortened.
[0011]
In this optical pickup device, spherical aberration can be corrected by variably controlling the distance between the convex lens 106 and the concave lens 105 in the beam expander.
[0012]
As a conventional optical pickup device, as shown in FIG. 11, there is an optical pickup device in which the size of the movable optical block 116 is reduced by increasing the number of deflecting portions of the light beam.
[0013]
That is, in this optical pickup device, in the fixed optical block 115, the light beam emitted from the semiconductor laser 101 passes through the first beam splitter 104 and is made into a parallel light beam by the collimator lens 102. The parallel light beam enters the beam splitter plate 117 and is split into a light beam transmitted through the beam splitter plate 117 and a light beam reflected by the beam splitter plate 117. The light beam transmitted through the beam splitter plate 117 is received by the photodetector 110. In the optical pickup device, the light emission output of the semiconductor laser 101 is feedback-controlled based on the output of the photodetector 110, so that the light emission amount of the semiconductor laser 101 is kept constant.
[0014]
The light beam reflected by the beam splitter plate 117 is shaped into a light beam having an isotropic light amount distribution (light beam cross-sectional intensity distribution) by the anamorphic prism 103, and emitted from the fixed optical block 115.
[0015]
The light beam emitted from the fixed optical block 115 enters the movable optical block 116, enters the second beam splitter 118 in the movable optical block 116, and is deflected by 90 ° by the second beam splitter 118. . This light beam passes through a spherical aberration correcting beam expander including a concave lens 105 and a convex lens 106, is deflected by a rising mirror 107 in a direction perpendicular to the optical disk 109, and is converted into λ / 4 (4 The light is incident on the objective lens 108 via the (sub-wavelength) plate 114. The light beam incident on the objective lens 108 is condensed by the objective lens 108 on the signal recording surface of the optical disk 109 as a minute light spot.
[0016]
The light beam reflected on the signal recording surface of the optical disk 109 passes through the objective lens 108 again, passes through the λ / 4 plate 114, is deflected by the rising mirror 107, passes through the convex lens 106 and the concave lens 105 of the beam expander, and The process returns to the second beam splitter 118. The light beam returned to the second beam splitter 118 is deflected by 90 ° by the second beam splitter 118, emitted from the movable optical block 116, and enters the fixed optical block 115.
[0017]
In the fixed optical block 115, the return light from the optical disk 109 returns to the first beam splitter 104 via the anamorphic prism 103, the beam splitter plate 117, and the collimator lens 102. In the beam splitter 104, the return light from the optical disk 109 is reflected and deflected, and is condensed on the light receiving surface of the photodetector 112 by the detection lens 119.
[0018]
In this optical pickup device, in order to access an information track having a predetermined purpose, only the movable optical block 116 is moved in the tracking direction, which is the radial direction of the optical disk 109, as shown by the arrow T in FIG. Just fine. Therefore, in this optical pickup device, the movable optical block 116 can be started and stopped at a high speed, and the access time to the target information track can be shortened.
[0019]
Also in this optical pickup device, the spherical aberration can be corrected by variably controlling the distance between the convex lens 106 and the concave lens 105 in the beam expander.
[0020]
In FIGS. 10 and 11, in order to clarify the drawings, the mirror 107, the λ / 4 plate 114, and the objective lens 108 are rotated by 90 ° around the optical axis at point A in FIGS. Are shown without overlapping. Actually, the light beam deflected by the rising mirror 107 travels in a direction perpendicular to the plane of the drawing, so that the rising mirror 107, the λ / 4 plate 114, and the objective lens 108 appear to be coaxially overlapped. become.
[0021]
[Problems to be solved by the invention]
By the way, in the conventional optical pickup device shown in FIG. 10 described above, on the assumption that the incident light beam from the fixed optical block 115 to the movable optical block 116 is at a correct position, the light beam is reflected and deflected. If there is an error in the mounting position of the raising mirror 107 to the movable optical block 116, the optical axis of the light beam incident on the objective lens 108 will be tilted or shifted. Then, this light beam becomes so-called off-axis light with respect to the objective lens 108, and has a factor of increasing aberration and deteriorating recording / reproducing characteristics.
[0022]
In particular, since the tilt of the optical axis occurs at twice the angle error (tilt) of the mounting mirror 107, high accuracy is required for the mounting angle of the rising mirror 107.
[0023]
In the conventional optical pickup device shown in FIG. 11, two optical elements for reflecting and deflecting a light beam, that is, a second beam splitter 118 and a rising mirror 107 are provided in a movable optical block 116. The accuracy of the mounting angle of the second beam splitter 118 and the rising mirror 107 is required to be higher than that of the optical pickup device shown in FIG.
[0024]
Therefore, in any of the above-described optical pickup devices, an angle adjustment mechanism (a tilt adjustment mechanism) is required in order to suppress a mounting error of the rising mirror 107 and the like. However, in the above-described optical pickup device, when the angle adjustment mechanism of the optical element is provided, the movable optical block 116 is increased in size and weight. When the size of the movable optical block 116 increases and the weight increases, the driving force of the motor for moving the movable optical block 116 needs to be increased, and the size of the motor increases. As a result, the size of the entire optical pickup device and the size of a recording / reproducing device configured using the optical pickup device are increased.
[0025]
In addition, instead of a rising mirror or a beam splitter, which is an optical element that requires high accuracy in the mounting position because the light beam is reflected only once, the light beam is internally reflected twice in the optical element to deflect the light beam. It is conceivable to use an optical element such as a pentaprism. In this case, the required accuracy of the mounting position of the optical element is relaxed. However, there is a problem that such an optical element is more difficult to manufacture and costs higher than a mirror or the like.
[0026]
In the above-described optical pickup device, it is conceivable that all of the above-described optical elements are arranged in an integrated optical block without being separated into a fixed optical block and a movable optical block.
[0027]
In this case, with the beam expander including the two lenses 105 and 106 removed from the optical path, the position of the semiconductor laser 101 is adjusted so that the light beam reflected by the rising mirror 107 is perpendicularly incident on the objective lens 108. (Position on the XY plane orthogonal to the optical axis).
[0028]
When such a position adjustment of the semiconductor laser 101 is performed in a state where the mounting angles of the optical elements such as the rising mirror 107 and the collimator lens 102 are shifted, the light beam emitted from the collimator lens 102 is shifted with respect to the original optical axis. It will be emitted at an angle. When the light beam emitted from the collimator lens 102 is inclined, the optical characteristics of an optical element having an angle dependence, such as a polarizing film of a beam splitter, change because the incident angle of the light beam changes. In addition, if the beam expander is inserted on the optical path after the position adjustment of the semiconductor laser 101, the light beam will be further inclined.
[0029]
Therefore, the present invention has been proposed in view of the above situation, and has a sufficient light emitting wavelength of a light source, a high numerical aperture (NA) of an objective lens, and a sufficient mounting position of an optical element. The present invention provides an optical pickup device capable of coping with an optical disk having a higher recording density of an information signal than the conventional one by ensuring the accuracy easily, and also provides a method of manufacturing such an optical pickup device. It is an object of the present invention to provide a recording / reproducing apparatus which can use an optical disk having a higher recording density of information signals than before by using an optical pickup device.
[0030]
[Means for Solving the Problems]
In order to solve the above problems, an optical pickup device according to the present invention comprises a light source, an objective lens for condensing a light beam emitted from the light source on a signal recording surface of an optical recording medium, a concave lens and a convex lens. A beam expander in which a distance between the concave lens and the convex lens is arranged on an optical path from a light source to an objective lens to correct a spherical aberration generated in a transparent cover layer formed on a signal recording surface in the medium, and Light detecting means for detecting a light beam reflected by the signal recording surface of the light beam, and the beam expander has another optical element by adjusting the relative positions of the concave lens and the convex lens in two directions orthogonal to the optical axis. Is characterized in that aberrations caused by mounting errors of the above are corrected.
[0031]
In this optical pickup device, since the relative position of the concave lens and the convex lens of the beam expander is adjusted in two directions perpendicular to the optical axis, the aberration caused by the mounting error of the other optical element is corrected. As a whole, sufficient optical characteristics are maintained.
[0032]
This optical pickup device is a so-called "integrated type" optical pickup device, but the optical pickup device according to the present invention can be configured as a so-called "separable type" optical pickup device.
[0033]
That is, an optical pickup device according to the present invention includes a fixed optical system having a light source and a collimator lens and fixedly disposed in a recording and reproducing device, and an objective lens having an objective lens and a light source of the objective lens in the recording and reproducing device. The axis is supported with the axis perpendicular to the signal recording surface of the optical recording medium and can be moved and operated in a direction parallel to the signal recording surface.Then, the light is emitted from the light source and emitted from the fixed optical system via the collimator lens. A movable optical system for receiving the parallel light beam and condensing the light beam on the signal recording surface of the optical recording medium by the objective lens, and a transparent cover layer comprising a concave lens and a convex lens and formed on the signal recording surface in the optical recording medium. The distance between the concave lens and the convex lens, which is disposed on the optical path from the light source to the objective lens, is And a light detecting means for detecting a light beam reflected by the signal recording surface of the light beam. In the beam expander, the relative positions of the concave lens and the convex lens are adjusted in two directions orthogonal to the optical axis. In this way, aberrations caused by mounting errors of other optical elements are corrected.
[0034]
In this optical pickup device, since the relative position of the concave lens and the convex lens of the beam expander is adjusted in two directions perpendicular to the optical axis, the aberration caused by the mounting error of the other optical element is corrected. As a whole, sufficient optical characteristics are maintained.
[0035]
The method for manufacturing an optical pickup device according to the present invention includes a light source, an objective lens for condensing a light beam emitted from the light source on a signal recording surface of the optical recording medium, a concave lens and a convex lens, A beam expander disposed on an optical path from a light source to an objective lens for correcting spherical aberration generated in a transparent cover layer formed on a recording surface and having a variable distance between a concave lens and a convex lens; and a signal recording surface of a light beam. A light detecting means for detecting a reflected light beam due to the optical pickup device, wherein the relative position in two directions orthogonal to the optical axis of the concave lens and the convex lens forming a beam expander is adjusted, This is characterized in that the aberration generated due to the mounting error of the optical element is corrected.
[0036]
In the method of manufacturing the optical pickup device, since the relative position of the concave lens and the convex lens of the beam expander is adjusted in two directions orthogonal to the optical axis, the aberration caused by the mounting error of another optical element is corrected. Sufficient optical characteristics can be maintained for the entire optical system.
[0037]
This method of manufacturing an optical pickup device is a method of manufacturing a so-called "integrated type" optical pickup device, but the present invention can also be applied to a method of manufacturing a so-called "separable type" optical pickup device.
[0038]
That is, the method for manufacturing an optical pickup device according to the present invention includes a fixed optical system having a light source and a collimator lens and fixedly disposed in a recording / reproducing device; The optical axis of the objective lens is supported with the optical axis perpendicular to the signal recording surface of the optical recording medium, and can be moved in the direction parallel to the signal recording surface. A movable optical system which receives a parallel light beam emitted from the system and condenses the light beam on the signal recording surface of the optical recording medium by the objective lens; and a concave lens and a convex lens, which are formed on the signal recording surface in the optical recording medium. The distance between the concave lens and the convex lens is arranged on the optical path from the light source to the objective lens to correct spherical aberration generated in the transparent cover layer. A variable beam expander, and a light detecting means for detecting a light beam reflected by the signal recording surface of the light beam, a method for manufacturing an optical pickup device, wherein the optical system is orthogonal to the optical axes of a concave lens and a convex lens forming a beam expander. By adjusting the relative positions in the two directions described above, aberrations caused by mounting errors of other optical elements are corrected.
[0039]
In the method of manufacturing the optical pickup device, since the relative position of the concave lens and the convex lens of the beam expander is adjusted in two directions orthogonal to the optical axis, the aberration caused by the mounting error of another optical element is corrected. Sufficient optical characteristics can be maintained for the entire optical system.
[0040]
The recording / reproducing apparatus according to the present invention includes a medium supporting means for supporting the optical recording medium, a light source, and an optical axis supported by being perpendicular to a signal recording surface of the optical recording medium supported by the medium supporting means. An objective lens that is movable in a direction parallel to the signal recording surface and condenses a light beam emitted from a light source on the signal recording surface, and a transparent lens formed on the signal recording surface in the optical recording medium, comprising a concave lens and a convex lens. A beam expander which is arranged on an optical path from a light source to an objective lens and has a variable distance between the concave lens and the convex lens in order to correct spherical aberration generated in the cover layer, and detects a light beam reflected by a signal recording surface of the light beam. The beam expander includes a light detecting unit, and a signal processing unit that performs signal processing on a light detection output from the light detecting unit. By the relative position of the concave lens and the convex lens is adjusted, and is characterized in that to correct the aberration generated by the mounting error of other optical elements.
[0041]
In this recording / reproducing apparatus, the aberration generated due to the mounting error of the other optical element is corrected by adjusting the relative positions of the concave lens and the convex lens of the beam expander in two directions orthogonal to the optical axis. As a whole, sufficient optical characteristics are maintained.
[0042]
This recording / reproducing apparatus is a recording / reproducing apparatus having a so-called “integrated” optical pickup device, but the recording / reproducing apparatus according to the present invention is a recording / reproducing apparatus having a so-called “separable” optical pickup device. It can also be configured.
[0043]
That is, the recording / reproducing apparatus according to the present invention has a medium supporting means for supporting an optical recording medium, a fixed optical system having a light source and a collimator lens and fixedly disposed in the recording / reproducing apparatus, and an objective lens. In the recording / reproducing apparatus, the objective lens is supported so that the optical axis of the objective lens is perpendicular to the signal recording surface of the optical recording medium supported by the medium supporting means, and can be moved in a direction parallel to the signal recording surface. A movable optical system which receives a parallel light beam emitted from a light source, is emitted from a fixed optical system through a collimator lens, and condenses the light beam on a signal recording surface of an optical recording medium by the objective lens; and a concave lens. And on the optical path from the light source to the objective lens for compensating for spherical aberration occurring in the transparent cover layer formed on the signal recording surface in the optical recording medium. A beam expander which is disposed and has a variable distance between the concave lens and the convex lens; a light detecting means for detecting a light beam reflected by the signal recording surface of the light beam; and a signal processing means for performing signal processing on a light detection output from the light detecting means The beam expander is characterized in that, in two directions orthogonal to the optical axis, the relative positions of the concave lens and the convex lens are adjusted, thereby correcting aberrations caused by mounting errors of other optical elements. Is what you do.
[0044]
In this recording / reproducing apparatus, the aberration generated due to the mounting error of the other optical element is corrected by adjusting the relative positions of the concave lens and the convex lens of the beam expander in two directions orthogonal to the optical axis. As a whole, sufficient optical characteristics are maintained.
[0045]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0046]
In this embodiment, an optical pickup device according to the present invention is configured so as to use an optical disk as an optical recording medium.
[0047]
The optical pickup device according to the present invention incorporates a semiconductor laser 1 as a light source as shown in FIG. 1, and is fixedly arranged on a chassis 2 in the recording and reproducing device according to the present invention as shown in FIG. A movable optical system having a fixed optical system 3 and an objective lens 4, which are arranged so as to be movable on the chassis 2 in the recording / reproducing apparatus, and into which a light beam emitted from the semiconductor laser 1 is incident. And a system 5. The fixed optical system 3 and the movable optical system 5 are provided in the fixed optical block 3a and the movable optical block 5a, respectively. The fixed optical block 3 a is fixedly disposed on the chassis 2.
[0048]
In the fixed optical system 3, as shown in FIG. 1, a light beam emitted from the semiconductor laser 1 is converted into a parallel light beam by a collimator lens 6, and is further distributed isotropically by an anamorphic prism 7a (light beam distribution). After being shaped into a light beam having a (cross-sectional intensity distribution), it becomes a grating (diffraction grating) 7b that splits the light beam for performing tracking servo by the so-called “three-beam method” and an optical rotator for adjusting the polarization direction of the light beam. The light enters the beam splitter 8 via a λ / 2 plate (a half-wave plate) 7c.
[0049]
In this optical pickup device, in order to keep the amount of light emitted from the semiconductor laser 1 constant, a parallel light beam transmitted through the beam splitter 8 is received by the photodetector 9 and the output of the semiconductor laser 1 is detected based on the output of the photodetector 9. The light emission output is feedback controlled.
[0050]
The parallel light beam reflected by the beam splitter 8 is emitted from the fixed optical block 3a. The parallel light flux emitted from the fixed optical block 3a enters the movable optical block 5a.
[0051]
As shown in FIG. 2, the movable optical system 5 disposed in the movable optical block 5a is used to move the optical axis of the objective lens 4 to the axis of the spindle motor 10 for rotating the optical disc 109 in the recording / reproducing apparatus, that is, the spindle. It is supported parallel to the axis 10a. The movable optical system 5 is configured such that the movable optical block 5a is guided by a shaft 11 disposed on the chassis 2 so that the objective lens 4 moves relative to the spindle shaft 10a as shown by an arrow T in FIG. It can be moved in the direction of coming and going.
[0052]
As shown in FIG. 2, a disk table 12 is attached to the tip end of the spindle shaft 10a, and the disk table 12 supports the center of the optical disk 109. When the spindle motor 10 is driven and the spindle shaft 10 a is rotated, the optical disk 109 is rotated together with the disk table 12.
[0053]
As shown in FIG. 1, the parallel light beam incident on the movable optical block 5a is incident on a mirror 15a via a beam expander including a concave lens 13 and a convex lens 14 for correcting spherical aberration. The mirror 15a reflects and deflects the parallel light beam emitted from the fixed optical system 3 and passes the light of the objective lens 4 through a λ / 4 (quarter wavelength) plate 15b for changing the light beam into circularly polarized light. Guide in a direction crossing the axis.
[0054]
A rising mirror 16 is disposed at the intersection of the optical path of the parallel light flux deflected by the mirror 15a and passing through the λ / 4 (quarter wavelength) plate 15b and the optical axis of the objective lens 4. The rising mirror 16 deflects the light flux guided by the mirror 15 a in a direction intersecting the optical axis of the objective lens 4 in the optical axis direction of the objective lens 4, that is, in a direction perpendicular to the main surface of the optical disc 109. , And is incident on the objective lens 4. The parallel light beam incident on the objective lens 4 is condensed by the objective lens 4 on the signal recording surface of the optical disk 109 as a minute light spot.
[0055]
In FIG. 1, in order to clarify the drawing, the mirror is rotated by 90 ° around the optical axis at point A in FIG. 1 so that the rising mirror 16, the λ / 4 plate 15b, and the objective lens 4 do not overlap. FIG. Actually, since the light beam deflected by the rising mirror 16 travels in a direction perpendicular to the plane of the drawing, the rising mirror 16, the λ / 4 plate 15b, and the objective lens 4 appear to be coaxially overlapped. become.
[0056]
The light beam reflected on the signal recording surface of the optical disk 109 passes through the objective lens 4 again, is deflected by the rising mirror 16, passes through the λ / 4 plate 15b, and is further deflected by the mirror 15a. This light beam passes through the convex lens 14 and the concave lens 13 of the beam expander, is emitted from the movable optical block 5a, and returns to the fixed optical block 3a.
[0057]
In the fixed optical system 3 in the fixed optical block 3a, the return light from the optical disk 109 returns to the beam splitter 8. In the beam splitter 8, return light from the optical disk 109 passes through a reflecting surface that separates a light beam going to the photodetector 9 from a light beam going to the movable optical system 5, and is condensed by a condensing lens 17 as light that serves as a light detecting unit The light is collected on the light receiving surface of the detector 18. The photodetector 18 detects the light beam condensed by the objective lens 4 on the signal recording surface of the optical disk 109 and reflected by the signal recording surface in this manner.
[0058]
In this optical pickup device, by controlling the distance between the concave lens 13 and the convex lens 14 in the beam expander, the thickness of the transparent cover layer 109a formed on the signal recording surface of the optical disk 109 causes an error depending on the location. It is possible to correct spherical aberration caused by having.
[0059]
In the correction of the spherical aberration, when the convex lens 14 which is the objective lens 4 side of the concave lens 13 and the convex lens 14 forming the beam expander is moved in the optical axis direction, the movement of the beam expander becomes effective. The diameter fluctuates, and the output (board power) of the light beam irradiated onto the optical disk 109 fluctuates. Therefore, in order to correct the spherical aberration, it is desirable to move the concave lens 13 farthest from the objective lens 4 in the optical axis direction among the concave lens 13 and the convex lens 14 forming the beam expander. Even if the concave lens 13 is moved in the optical axis direction, the output (board power) of the light beam irradiated on the optical disk 109 does not change.
[0060]
In this optical pickup device, in order to access an information track having a predetermined purpose, only the movable optical block 5a is supported by the objective lens 4 supporting the central portion of the optical disk 109 as shown by an arrow T in FIG. What is necessary is just to move in the tracking direction which comes in contact with / separates from the spindle shaft 10a. Therefore, in this optical pickup device, the movable optical system 5 can be started and stopped at high speed, and the access time to the target information track can be shortened.
[0061]
Further, in this optical pickup device, a parallel light beam incident on the movable optical system 5 from the fixed optical system 3 passes through an optical path L1 parallel to the direction in which the objective lens 4 can be moved and indicated by an arrow T in FIG. Further, the light enters the movable optical system 5 from the side where the spindle motor 10 is provided. That is, the fixed optical system 3 and the movable optical system 5 are arranged at positions opposite to each other with respect to the spindle motor 10 so as to face each other with the spindle motor 10 interposed therebetween.
[0062]
For this reason, in the optical pickup device and the recording / reproducing device, the fixed optical system 3 and the movable optical system 5 are almost equally distributed with respect to the center of the optical disk 109 whose center is supported by the spindle 10a. And is substantially contained in a region corresponding to a disk cartridge configured to store the optical disk 109.
[0063]
The disk cartridge includes an optical disk 109 and a thin housing-like cartridge that rotatably stores the optical disk 109. The cartridge has a main surface portion substantially corresponding to a square circumscribing the optical disk 109.
[0064]
Therefore, the outer casing of the recording / reproducing apparatus can have a size substantially corresponding to the size of the disc cartridge, that is, the size of the area substantially corresponding to the square circumscribing the optical disc 109.
[0065]
For example, assuming that the diameter of the optical disk 109 is 50 mm, in order to configure a small-sized recording / reproducing apparatus, the outer housing of the recording / reproducing apparatus has a size of a disk cartridge configured to house the optical disk 109, that is, The size can be about 55 mm in length and about 55 mm in width, and sufficient miniaturization can be achieved.
[0066]
As described above, in this optical pickup device, in order to reduce the size of the entire optical pickup device, the optical path from the semiconductor laser 1 is deflected by 90 ° by the beam splitter 8 in the fixed optical system 3, and , The mirror 15a and the rising mirror 16 perform 90 ° deflection twice. Therefore, the mounting accuracy of the mirror 15a and the rising mirror 16 is required to be extremely strict and high.
[0067]
In this optical pickup device, during the manufacturing process of the optical pickup device, the beam expander adjusts the relative positions of the concave lens 13 and the convex lens 14 in two directions orthogonal to the optical axis, thereby producing another beam. The aberration generated due to the mounting error of the optical element is corrected.
[0068]
In this adjustment, of the concave lens 13 and the convex lens 14 forming the beam expander, the convex lens 14 serving as the fixed lens is positioned in two directions perpendicular to the optical axis as indicated by arrows X and Y in FIG. It is desirable to adjust. By adjusting the movement of the convex lens 14 as described above, the aberration caused by the mounting error (tilt) of the mirror 15a or the like is corrected.
[0069]
That is, in manufacturing the optical pickup device, first, the fixed optical system 3 is configured in the fixed optical block 3a such that the position of the parallel light beam emitted from the fixed optical system 3 is at a predetermined position on the chassis 2. I do. In this case, the relative position between the optical elements constituting the fixed optical system 3 is configured to have no inclination, and the position of the fixed optical block 3a on the chassis 2 is adjusted so that the light is emitted from the fixed optical system 3. The position of the parallel light beam to be performed is defined as a predetermined position.
[0070]
Next, in configuring the movable optical system 5, first, two mirrors, a mirror 15a and a rising mirror 16, are attached to the movable optical block 5a. Since the mirror 15a and the rising mirror 16 are mounted on the movable optical block 5a with reference to the mounting surface of the movable optical block 5a, the accuracy of the mounting position of each mirror depends on the processing accuracy of the movable optical block 5a. It becomes. Then, in a state where the movable optical block 5a is disposed on the chassis 2, the position of the convex lens 14, which is a fixed-side lens of the beam expander, is adjusted for the aberration caused by the error in the mounting position of these two mirrors. Thus, the convex lens 14 is fixed.
[0071]
For example, when it is assumed that the mounting error between the two mirrors of the mirror 15a and the rising mirror 16 is 0.2 °, the optical axis of the light beam reflected by the two mirrors is at most 0. The optical axis tilts by 8 ° (causing an optical axis tilt of 0.8 °). When a light beam whose optical axis is inclined by 0.8 ° is incident on the objective lens 4, the wavefront aberration of the light beam emitted from the objective lens 4 deteriorates to about 0.05λrms as shown in FIG.
[0072]
Then, as described above, when the optical axis of the light beam incident on the objective lens 4 is inclined by 0.8 °, the objective lens is designed to minimize the wavefront aberration in the light beam emitted from the objective lens 4. Assuming that the adjustment of tilting the lens 4 is performed, as shown in FIG. 4, when the objective lens 4 is tilted by about 0.2 ° is the minimum, however, the improvement is still only up to about 0.03λrms.
[0073]
In this optical pickup device, as described above, when the optical axis of the light beam incident on the objective lens 4 is inclined by 0.8 °, the convex lens 14 which is the fixed lens of the beam expander is only about 400 μm. The light beam is moved in a direction perpendicular to the optical axis and corrected so that the incident angle of the light beam on the objective lens 4 becomes 0 °. For this reason, in this optical pickup device, as shown in FIG. 5, the wavefront aberration of the light beam that enters the objective lens 4 via the beam expander and exits from the objective lens 4 is suppressed to 0.01 λrms. The aberration occurring at this time is due to the eccentricity of the lens in the beam expander, but has a sufficiently small amount of aberration, and is of an allowable degree for maintaining the optical characteristics of the optical pickup device. It is.
[0074]
The position adjusting mechanism for moving the fixed-side lens of the beam expander may be, for example, a mechanism for moving the lens by pushing the lens in a direction perpendicular to the optical axis by a screw feed mechanism or the like. Such a mechanism requires a simple structure as compared with a mechanism for adjusting the tilt of the mirror (tilt adjustment) requiring a rotation fulcrum. Therefore, the position adjusting mechanism for moving the fixed-side lens of the beam expander does not increase the size of the optical pickup device.
[0075]
As described above, in this optical pickup device, the wavefront aberration in the light beam emitted from the objective lens 4 caused by an error in the mounting positions of the two mirrors, the mirror 15a and the rising mirror 16, causes the lens aberration in the beam expander to be increased. It is sufficiently suppressed by the position adjustment in the direction perpendicular to the optical axis.
[0076]
Further, in this optical pickup device, since the configuration of the lens position adjustment mechanism in the beam expander is simple, the increase in the size of the movable optical block device configuration is suppressed as compared with the case where a mirror tilt adjustment mechanism is provided. The movable optical block can be reduced in size and weight. Since the movable optical block can be reduced in size and weight as described above, a small motor can be used as a motor for moving the movable optical block. Therefore, the entire configuration of the optical pickup device and the use of the optical pickup device are reduced. It is also possible to reduce the size of the recording / reproducing apparatus configured as described above.
[0077]
Further, in this optical pickup device, since it is not necessary to use a prism having a complicated shape such as a pentaprism in the movable optical block, it is easy to manufacture and assemble the parts, and to reduce the cost of the parts. be able to.
[0078]
In the optical pickup device and the recording / reproducing device constituted by using the optical pickup device, a laser driver which is a drive circuit of a semiconductor laser is a heat source. The laser driver can radiate heat from the laser driver to the chassis 2 of the recording / reproducing apparatus.
[0079]
The optical pickup device according to the present invention can be configured using an integrated optical block as shown in FIG.
[0080]
That is, the optical pickup device is guided by the shaft 11 provided on the chassis, and becomes a light source in the movable optical block 5a which can be moved as shown by the arrow T in FIG. The semiconductor laser 1 is built in. The light beam emitted from the semiconductor laser 1 is converted into a parallel light beam by a collimator lens 6 and further shaped by an anamorphic prism 7a into a light beam having an isotropic light amount distribution (light beam cross-sectional intensity distribution). A grating (diffraction grating) 7b for dividing a light beam for performing tracking servo by a so-called "three-beam method" and a λ / 2 plate (half-wave plate) 7c serving as an optical rotator for adjusting the polarization direction of the light beam are provided. After that, the light enters the beam splitter 8.
[0081]
In this optical pickup device, in order to keep the amount of light emitted from the semiconductor laser 1 constant, a parallel light beam transmitted through the beam splitter 8 is received by the photodetector 9 and the output of the semiconductor laser 1 is detected based on the output of the photodetector 9. The light emission output is feedback controlled.
[0082]
The parallel light flux reflected by the beam splitter 8 is incident on a mirror 15a via a beam expander including a concave lens 13 and a convex lens 14 for correcting spherical aberration. The mirror 15a reflects and deflects the parallel light beam emitted from the fixed optical system 3 and passes the light of the objective lens 4 through a λ / 4 (quarter wavelength) plate 15b for changing the light beam into circularly polarized light. Guide in a direction crossing the axis.
[0083]
A rising mirror 16 is disposed at the intersection of the optical path of the parallel light flux deflected by the mirror 15a and passing through the λ / 4 (quarter wavelength) plate 15b and the optical axis of the objective lens 4. The rising mirror 16 deflects the light flux guided by the mirror 15 a in a direction intersecting the optical axis of the objective lens 4 in the optical axis direction of the objective lens 4, that is, in a direction perpendicular to the main surface of the optical disc 109. , And is incident on the objective lens 4. The parallel light beam incident on the objective lens 4 is condensed by the objective lens 4 on the signal recording surface of the optical disk 109 as a minute light spot.
[0084]
In FIG. 6, in order to clarify the drawing, it is rotated by 90 ° around the optical axis at point A in FIG. 6 so that the rising mirror 16, the λ / 4 plate 15b, and the objective lens 4 do not overlap. FIG. Actually, since the light beam deflected by the rising mirror 16 travels in a direction perpendicular to the plane of the drawing, the rising mirror 16, the λ / 4 plate 15b, and the objective lens 4 appear to be coaxially overlapped. become.
[0085]
The movable optical block 5a is guided by a shaft 11 provided on a chassis, and can be moved in a direction in which the objective lens 4 comes into contact with and separates from the spindle shaft 10a as shown by an arrow T in FIG. It has been done. The spindle shaft 10a has a disk table 12 attached to the distal end side, and the disk table 12 supports a central portion of the optical disk 109. When the spindle motor 10 is driven and the spindle shaft 10 a is rotated, the optical disk 109 is rotated together with the disk table 12.
[0086]
The light beam reflected on the signal recording surface of the optical disk 109 passes through the objective lens 4 again, is deflected by the rising mirror 16, passes through the λ / 4 plate 15b, and is further deflected by the mirror 15a. This light beam passes through the convex lens 14 and the concave lens 13 of the beam expander and returns to the beam splitter 8. In the beam splitter 8, return light from the optical disk 109 passes through a reflecting surface that separates a light beam going to the photodetector 9 from a light beam going to the movable optical system 5, and is condensed by a condensing lens 17 as light that serves as a light detecting unit The light is collected on the light receiving surface of the detector 18. The photodetector 18 detects the light beam condensed by the objective lens 4 on the signal recording surface of the optical disk 109 and reflected by the signal recording surface in this manner.
[0087]
In this optical pickup device, by controlling the distance between the concave lens 13 and the convex lens 14 in the beam expander, the thickness of the transparent cover layer 109a formed on the signal recording surface of the optical disk 109 causes an error depending on the location. It is possible to correct spherical aberration caused by having.
[0088]
In the correction of the spherical aberration, when the convex lens 14 which is the objective lens 4 side of the concave lens 13 and the convex lens 14 forming the beam expander is moved in the optical axis direction, the movement of the beam expander becomes effective. The diameter fluctuates, and the output (board power) of the light beam irradiated onto the optical disk 109 fluctuates. Therefore, in order to correct the spherical aberration, it is desirable to move the concave lens 13 farthest from the objective lens 4 in the optical axis direction among the concave lens 13 and the convex lens 14 forming the beam expander. Even if the concave lens 13 is moved in the optical axis direction, the output (board power) of the light beam irradiated on the optical disk 109 does not change.
[0089]
In this optical pickup device, during the manufacturing process of the optical pickup device, the beam expander adjusts the relative positions of the concave lens 13 and the convex lens 14 in two directions orthogonal to the optical axis, thereby producing another beam. The aberration generated due to the mounting error of the optical element is corrected.
[0090]
In this adjustment, of the concave lens 13 and the convex lens 14 forming the beam expander, the convex lens 14 serving as the fixed lens is positioned in two directions perpendicular to the optical axis as indicated by arrows X and Y in FIG. It is desirable to adjust. By adjusting the movement of the convex lens 14 as described above, the aberration caused by the mounting error (tilt) of the mirror 15a or the like is corrected.
[0091]
That is, in manufacturing the optical pickup device, first, the beam from the semiconductor laser 1 is moved into the movable optical block 5a such that the position of the parallel light beam emitted from the beam splitter 8 is at a predetermined position in the movable optical block 5a. Each optical element up to the splitter 8 is provided. In this case, the relative position between the respective optical elements from the semiconductor laser 1 to the beam splitter 8 is configured to have no inclination with reference to the mounting surface (positioning portion) formed in the movable optical block 5a. . As described above, by not adjusting the position of the semiconductor laser 1, the inclination of the light beam due to the shift of the mounting angle of each optical element, particularly the inclination of the light beam emitted from the collimator lens 6 into which the light beam emitted from the semiconductor laser 1 is incident. Can be prevented from occurring.
[0092]
Next, two mirrors, the mirror 15a and the rising mirror 16, are mounted in the movable optical block 5a. Since the mirror 15a and the rising mirror 16 are mounted on the movable optical block 5a with reference to the mounting surface of the movable optical block 5a, the accuracy of the mounting position of each mirror depends on the processing accuracy of the movable optical block 5a. It becomes. Then, due to a relative error in the mounting position between each optical element from the semiconductor laser 1 to the beam splitter 8 and each of the mirrors 15a and 16, the wavefront aberration generated in the light beam emitted from the objective lens 4 is reduced by a beam expander. The correction is performed by adjusting the position of the convex lens 14 which is the fixed-side lens, and the convex lens 14 is fixed.
[0093]
The position adjusting mechanism for moving the fixed-side lens of the beam expander may be, for example, a mechanism for moving the lens by pushing the lens in a direction perpendicular to the optical axis by a screw feed mechanism or the like. Such a mechanism requires a simple structure as compared with a mechanism for adjusting the tilt of the mirror (tilt adjustment) requiring a rotation fulcrum. Therefore, the position adjusting mechanism for moving the fixed-side lens of the beam expander does not increase the size of the optical pickup device.
[0094]
As described above, in this optical pickup device, the wavefront aberration in the light beam emitted from the objective lens 4 caused by an error in the mounting positions of the two mirrors, the mirror 15a and the rising mirror 16, causes the lens aberration in the beam expander to be increased. It is sufficiently suppressed by the position adjustment in the direction perpendicular to the optical axis.
[0095]
Further, in this optical pickup device, since the configuration of the lens position adjustment mechanism in the beam expander is simple, the increase in the size of the movable optical block device configuration is suppressed as compared with the case where a mirror tilt adjustment mechanism is provided. The movable optical block can be reduced in size and weight. Since the movable optical block can be reduced in size and weight as described above, a small motor can be used as a motor for moving the movable optical block. Therefore, the entire configuration of the optical pickup device and the use of the optical pickup device are reduced. It is also possible to reduce the size of the recording / reproducing apparatus configured as described above.
[0096]
Further, in this optical pickup device, since it is not necessary to use a prism having a complicated shape such as a pentaprism in the movable optical block, it is easy to manufacture and assemble the parts, and to reduce the cost of the parts. be able to.
[0097]
Incidentally, the objective lens 4 in each optical pickup device as described above is supported on the movable optical block 5a via a biaxial actuator 19, as shown in FIG. The biaxial actuator 19 has an actuator base 20 mounted on the movable optical block 5a, and a lens holder 22 mounted on the actuator base 20 via an elastic arm 21 and holding the objective lens 4. It is configured. The lens holder 22 is movable with respect to the actuator base 20 in a plane including two directions of an optical axis direction of the objective lens 4 and a direction orthogonal to the optical axis while the elastic arm 21 is elastically deformed. .
[0098]
In the two-axis actuator 19, a focus coil and a tracking coil (not shown) are attached to the lens holder 22. A magnet and a yoke (not shown) are mounted on the actuator base 20. These magnets and yokes constitute a magnetic circuit that positions the focus coil and the tracking coil in the magnetic field to be formed.
[0099]
In this two-axis actuator, when a drive current is supplied to the focus coil, the lens holder 22 is moved in the optical axis direction of the objective lens 4, that is, in the focus direction, by the interaction between the current and the magnetic field formed by the magnetic circuit. Is moved. In the two-axis actuator, when a driving current is supplied to the tracking coil, the lens holder 22 moves in a direction perpendicular to the optical axis of the objective lens by an interaction between the current and a magnetic field formed by a magnetic circuit. That is, the moving operation is performed in the tracking direction. That is, in the two-axis actuator 19, the lens holder 22 supplies an electric power to the focus coil and the tracking coil, so that the lens holder 22 has an arbitrary position in a plane including two directions of the optical axis direction of the objective lens 4 and the direction orthogonal to the optical axis. Can be moved in any direction.
[0100]
In the biaxial actuator 19, the light beam incident on the objective lens 4 via the rising mirror 16 passes through the through hole 23 formed in the bottom plate of the actuator base 20 and is incident on the objective lens 4. You.
[0101]
In the two-axis actuator 19, a drive current based on a focus error signal indicating a distance in the optical axis direction of the objective lens 4 between a focus point of the objective lens 4 and a signal recording surface of the optical disc 109 is supplied to the focus coil. Thus, a focus servo operation is performed. In the two-axis actuator 19, the focus coil and the tracking coil indicate the radial distance between the focal point of the objective lens 4 and the recording track formed on the signal recording surface of the optical disk 109 in the radial direction of the optical disk 109. The tracking servo operation is performed by supplying a drive current based on the tracking error signal. By performing such a focus servo operation and a tracking servo operation, the focal point of the objective lens 4 is always formed on a recording track on the signal recording surface of the optical disc 109.
[0102]
The biaxial actuator 19 may be provided with a skew adjustment mechanism for adjusting the skew (inclination) of the objective lens 4 with respect to the light beam incident on the objective lens 4 via the rising mirror 16. The skew adjustment mechanism includes a spherical projection 24 in which the bottom surface of the actuator base 20 bulges toward the movable optical block 5a and a concave spherical surface that supports the spherical projection 24 on the upper surface of the movable optical block 5a. And the spherical seat 25. One end of the actuator base 20 is pressed toward the movable optical block 5a by a compression coil spring 27 wound around a support 26 provided on the movable optical block 5a, as indicated by an arrow A in FIG. At the same time, the other end of the movable optical block 5a is moved to a predetermined position on the movable optical block 5a side by a pull screw 28 screwed into a screw hole formed in the upper surface of the movable optical block 5a, as shown by an arrow B in FIG. It is pulled and supported.
[0103]
In this skew adjustment mechanism, the position of the other end of the actuator base 20 is determined by the position of the screw head of the pull screw 28, and the spherical protrusion 24 and the spherical seat 25 are always pressed by the compression force of the compression coil spring 27. In contact. Therefore, if such pulling screws 28 are provided at positions in two or more directions when viewed from the optical axis of the objective lens 4, the amounts of insertion of these pulling screws into the screw holes of the movable optical block 5 a are adjusted. Thereby, the skew of the objective lens 4 with respect to the light beam incident on the objective lens 4 via the rising mirror 16 can be adjusted.
[0104]
By this skew adjustment, the inclination of the optical axis of the objective lens 4 with respect to the signal recording surface of the optical disk 109 can be prevented, and the occurrence of aberration due to such an inclination can be suppressed.
[0105]
In this skew adjustment mechanism, the rising mirror 16 is also attached to the actuator base 20 side, so that the objective lens 4 and the rising mirror 16 maintain a constant positional relationship with each other on the signal recording surface of the optical disk 109. May be configured to be able to adjust the inclination with respect to. By such a skew adjustment, the inclination of the optical axis of the light beam entering the objective lens 4 from the rising mirror 16 with respect to the signal recording surface of the optical disk 109 can be prevented, and the occurrence of aberration due to such an inclination can be suppressed. Can be.
[0106]
In this recording / reproducing apparatus, the inclination of the optical disc 109 with respect to the light beam emitted from the objective lens 4 may be adjusted by tilting the spindle motor 10 with respect to the chassis 2. In this case, as shown in FIG. 8, the spindle motor 10 is inserted through a through hole 29 formed in the center of the chassis 2 and is arranged through an adjustment plate 30 attached to the bottom. 2 supported. The adjustment plate 30 can be easily deformed with one end fixed to the chassis 2. By deforming the adjustment plate 30, the inclination of the spindle motor 10 with respect to the chassis 2 can be adjusted. . Then, in a state where the inclination of the spindle motor 10 with respect to the chassis 2 is optimized, a plurality of portions of the adjustment plate 30 are fixed to the chassis 2 by solder 31 so that the adjustment plate 30 is not deformed. Is fixed.
[0107]
By adjusting the inclination of the spindle motor 10 with respect to the chassis 2, the inclination of the signal recording surface of the optical disc 109 with respect to the optical axis of the light beam emitted from the objective lens 4 can be prevented, and the occurrence of aberration due to such inclination Can be suppressed.
[0108]
The recording / reproducing apparatus according to the present invention includes the optical pickup device and the spindle motor 10 on the chassis as described above, and also includes the servo control circuit 33 and the system controller 34 as shown in FIG. Unit.
[0109]
In this recording / reproducing apparatus, the spindle motor 10 is controlled by a servo control circuit 33 and a system controller 34, and is driven at a predetermined rotation speed. The optical pickup device 35 writes and reads information signals to and from the optical disk 109 that is rotated by the spindle motor 10. The movable optical system 5 of the optical pickup device 35 is moved by the feed motor 36 in the radial direction of the optical disk 109 mounted on the disk table 12. The optical pickup device 35 and the feed motor 36 are also controlled and driven by the servo control circuit 33.
[0110]
The optical pickup device 35 irradiates the signal recording surface of the optical disk 109 with a light beam and detects a reflected light beam of the light beam, thereby reading out an information signal from the signal recording surface. The signal read from the optical disk 109 by the optical pickup device 35 is amplified by the preamplifier 37 and sent to the signal modulation / demodulation and ECC block 38 and the servo control circuit 33. The signal modulation / demodulation and ECC block 38 modulates and demodulates a signal and adds an ECC (error correction code) according to the type of an optical disc to be reproduced. Further, the signal modulation / demodulation and ECC block 38 generates a focus error signal, a tracking error signal, a track discrimination signal, an RF signal and the like based on the transmitted signal. The servo control circuit 33 controls the optical pickup device 35 based on the focus error signal, tracking error signal, and track discrimination signal generated by the signal modulation / demodulation and ECC block 38.
[0111]
The signal demodulated in the signal modulation / demodulation and ECC block 38 is transmitted to an external computer 40 or the like via an interface 39 if the signal is, for example, data for data storage of a computer. In this case, the external computer 40 or the like can receive a signal recorded on the optical disc 109 as a reproduction signal.
[0112]
The optical pickup device 35 irradiates a light beam onto the signal recording surface of the optical disc 109 rotated by the spindle motor 10 based on the signal transmitted from the signal modulation / demodulation and ECC block 38. By irradiating such a light beam, an information signal is written on the signal recording surface of the optical disc 109.
[0113]
【The invention's effect】
As described above, in the optical pickup device and the recording / reproducing device according to the present invention, by adjusting the relative positions of the concave lens and the convex lens of the beam expander in two directions orthogonal to the optical axis, the mounting error of other optical elements may occur. Since the generated aberration is corrected, sufficient optical characteristics are maintained in the entire optical system.
[0114]
In the method of manufacturing an optical pickup device according to the present invention, by adjusting the relative positions of the concave lens and the convex lens of the beam expander in two directions orthogonal to the optical axis, aberrations caused by mounting errors of other optical elements are provided. Is corrected, sufficient optical characteristics can be maintained in the optical system as a whole.
[0115]
That is, according to the present invention, in an optical pickup device including a beam expander, particularly, in an optical pickup device of a separation optical system having a fixed optical block and a movable optical block, only a simple mechanism is added. The generated aberration, so-called tilt of the optical axis, can be corrected, and the required accuracy of the mounting angle of the rising mirror or the like can be reduced. In this case, the wavefront aberration of the light beam emitted from the objective lens is sufficiently reduced, and the optical pickup device is not increased in size.
[0116]
The present invention is more effective when the movable optical system of the optical pickup device has a large number of optical elements such as mirrors that reflect and deflect a light beam. In other words, an error in the mounting angle of the optical element that reflects and deflects the light beam causes the optical axis to be tilted by twice the angle. Therefore, when many such optical elements are used, higher mounting accuracy is required. Because it is required.
[0117]
In addition, the present invention provides a method for manufacturing an optical element in comparison with using an optical element, such as a pentaprism, which deflects the light flux by internally reflecting the light flux twice inside the optical element, instead of using a rising mirror or a beam splitter. And the cost is low.
[0118]
When the optical pickup device according to the present invention is configured such that all optical elements are arranged in an integrated optical block without being separated into a fixed optical block and a movable optical block, the position of the light source is adjusted. This eliminates the necessity of performing, and it is possible to prevent the inclination of the light beam due to the deviation of the mounting angle of each optical element, particularly the inclination of the light beam emitted from the collimator lens into which the light beam emitted from the light source enters.
[0119]
That is, according to the present invention, it is possible to shorten the emission wavelength of the light source, increase the numerical aperture (NA) of the objective lens, and easily secure a sufficient precision for the mounting position of the optical element, thereby achieving a conventional information signal. The present invention provides an optical pickup device capable of coping with an optical disk having a high recording density, a method of manufacturing such an optical pickup device, and a recording density of an information signal by using such an optical pickup device. It is possible to provide a recording / reproducing apparatus which can use an optical disk having a high cost.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of a main part of an optical pickup device and a recording / reproducing device according to the present invention (using a separated optical block).
FIG. 2 is a side view showing a configuration of a main part of the optical pickup device and the recording / reproducing device shown in FIG.
FIG. 3 is a graph showing a relationship between a tilt of a light beam incident on an objective lens and a wavefront aberration in a light beam emitted from the objective lens in the optical pickup device shown in FIG.
FIG. 4 shows an angle of tilt adjustment of the objective lens when the tilt of the light beam incident on the objective lens is 0.8 ° in the optical pickup device shown in FIG. 1 and a wavefront aberration in the light beam emitted from the objective lens. 3 is a graph showing the relationship of
5 shows the inclination of a light beam incident on the objective lens and the output from the objective lens when the lens of the beam expander is moved and adjusted to an optimum position in a plane perpendicular to the optical axis in the optical pickup device shown in FIG. It is a graph which shows the relationship with the wavefront aberration in an emitted light beam.
FIG. 6 is a plan view showing another configuration (using an integrated optical block) of a main part of an optical pickup device and a recording / reproducing device according to the present invention.
FIG. 7 is a sectional view showing a configuration of a skew adjustment mechanism of an objective lens in the optical pickup device.
FIG. 8 is a side view showing a configuration of a skew adjustment mechanism of a spindle motor in the recording / reproducing apparatus.
FIG. 9 is a block diagram showing a configuration of the recording / reproducing apparatus.
FIG. 10 is a plan view showing a configuration of a main part of a conventional optical pickup device (using a separated optical block) and a recording / reproducing device.
FIG. 11 is a plan view showing another example of a configuration of a main part of a conventional optical pickup device (using a separated optical block) and a recording / reproducing device.
[Explanation of symbols]
Reference Signs List 1 semiconductor laser, 2 chassis, 3 fixed optical system, 3a fixed optical block, 4 objective lens, 5 movable optical system, 5a movable optical block, 6 collimator lens, 7a anamorphic prism, 8 beam splitter, 10 spindle motor, 13 Concave lens, 14 convex lens, 15 mirror, 16 rising mirror, 18 photodetector, 109 optical disk

Claims (18)

A light source,
An objective lens for condensing a light beam emitted by the light source on a signal recording surface of an optical recording medium,
A concave lens and a convex lens, which are arranged on an optical path from the light source to the objective lens in order to correct spherical aberration generated in a transparent cover layer formed on a signal recording surface in the optical recording medium; A beam expander in which the distance between the convex lenses is variable;
Light detecting means for detecting a light beam reflected by the signal recording surface of the light beam,
The beam expander is characterized in that the relative position of the concave lens and the convex lens is adjusted in two directions orthogonal to the optical axis, thereby correcting aberrations caused by mounting errors of other optical elements. Optical pickup device. 2. The optical pickup device according to claim 1, wherein the other optical element includes at least two or more optical elements for bending an optical path of a light beam from the light source. In the beam expander, one of the concave lens and the convex lens can be moved in the optical axis direction, and the other fixed lens corrects aberration caused by an error in mounting another optical element. 2. The optical pickup device according to claim 1, wherein the optical pickup device is adjusted in two directions orthogonal to the optical axis. 4. The optical pickup device according to claim 3, wherein the other optical element includes at least two optical elements for bending an optical path of a light beam from the light source. A fixed optical system having a light source and a collimator lens, and fixedly disposed in the recording / reproducing device;
In the recording / reproducing apparatus, the objective lens is supported so that the optical axis of the objective lens is perpendicular to the signal recording surface of the optical recording medium and can be moved in a direction parallel to the signal recording surface. A parallel light beam emitted from the light source, emitted from the fixed optical system via the collimator lens, is incident thereon, and the light beam is condensed on the signal recording surface of the optical recording medium by the objective lens. A movable optical system to
A concave lens and a convex lens, which are arranged on an optical path from the light source to the objective lens in order to correct spherical aberration generated in a transparent cover layer formed on a signal recording surface in the optical recording medium; A beam expander in which the distance between the convex lenses is variable;
Light detecting means for detecting a light beam reflected by the signal recording surface of the light beam,
The beam expander is characterized in that the relative position of the concave lens and the convex lens is adjusted in two directions orthogonal to the optical axis, thereby correcting aberrations caused by mounting errors of other optical elements. Optical pickup device. 6. The optical pickup device according to claim 5, wherein the other optical element includes at least two optical elements for bending an optical path of a light beam from the light source. In the beam expander, one of the concave lens and the convex lens can be moved in the optical axis direction, and the other fixed lens corrects aberration caused by an error in mounting another optical element. 6. The optical pickup device according to claim 5, wherein the optical pickup device is adjusted in two directions orthogonal to the optical axis. 8. The optical pickup device according to claim 7, wherein the other optical element has at least two optical elements for bending an optical path of a light beam from the light source. A light source, an objective lens for condensing a light beam emitted by the light source on a signal recording surface of the optical recording medium, and a spherical surface formed of a concave lens and a convex lens and formed on a transparent cover layer formed on the signal recording surface in the optical recording medium. A beam expander disposed on an optical path from the light source to the objective lens to correct aberration, wherein a distance between the concave lens and the convex lens is variable, and a light for detecting a light beam reflected by the signal recording surface of the light beam A method for manufacturing an optical pickup device including a detecting unit,
An optical pickup for correcting an aberration caused by an installation error of another optical element by adjusting a relative position of the concave lens and the convex lens forming the beam expander in two directions orthogonal to an optical axis. Device manufacturing method. The method for manufacturing an optical pickup device according to claim 9, wherein at least two or more optical elements for bending an optical path of a light beam from the light source are used as the other optical elements. The beam expander is a lens in which one of the concave lens and the convex lens is operable to move in the optical axis direction,
10. The method of manufacturing an optical pickup device according to claim 9, wherein the other fixed lens is adjusted in two directions orthogonal to the optical axis to correct an aberration caused by a mounting error of another optical element. The method of manufacturing an optical pickup device according to claim 11, wherein at least two or more optical elements for bending an optical path of a light beam from the light source are used as the other optical elements. A fixed optical system having a light source and a collimator lens and fixedly disposed in the recording / reproducing apparatus; A parallel light beam emitted from the light source, emitted through the collimator lens, and emitted from the fixed optical system, is incident on the parallel light beam, which is supported perpendicular to the signal recording surface and is movable in a direction parallel to the signal recording surface. A movable optical system for condensing a light beam on the signal recording surface of the optical recording medium by the objective lens; and a spherical aberration generated in a transparent cover layer formed on the signal recording surface in the optical recording medium, comprising a concave lens and a convex lens. A beam expander arranged on an optical path from the light source to the objective lens for correction, wherein a distance between the concave lens and the convex lens is variable. And da, a manufacturing method of an optical pickup device and a light detecting means for detecting the reflected light beam by the signal recording surface of the optical beam,
An optical pickup for correcting an aberration caused by an installation error of another optical element by adjusting a relative position of the concave lens and the convex lens forming the beam expander in two directions orthogonal to an optical axis. Device manufacturing method. 14. The method of manufacturing an optical pickup device according to claim 13, wherein at least two or more optical elements for bending an optical path of a light beam from the light source are used as the other optical elements. The beam expander is a lens in which one of the concave lens and the convex lens is operable to move in the optical axis direction,
14. The method of manufacturing an optical pickup device according to claim 13, wherein the other fixed lens is adjusted in two directions orthogonal to the optical axis to correct an aberration caused by a mounting error of another optical element. 16. The method for manufacturing an optical pickup device according to claim 15, wherein at least two or more optical elements for bending an optical path of a light beam from the light source are used as the other optical elements. Medium support means for supporting an optical recording medium;
A light source,
The optical axis is supported perpendicular to the signal recording surface of the optical recording medium supported by the medium supporting means, and the optical axis is movable in a direction parallel to the signal recording surface. An objective lens for focusing light on the signal recording surface,
A concave lens and a convex lens, which are arranged on an optical path from the light source to the objective lens in order to correct spherical aberration generated in a transparent cover layer formed on a signal recording surface in the optical recording medium; A beam expander in which the distance between the convex lenses is variable;
Light detection means for detecting a light beam reflected by the signal recording surface of the light beam,
Signal processing means for performing signal processing on a light detection output from the light detection means,
The beam expander is characterized in that the relative position of the concave lens and the convex lens is adjusted in two directions orthogonal to the optical axis, thereby correcting aberrations caused by mounting errors of other optical elements. Recording and playback device. Medium support means for supporting an optical recording medium;
A fixed optical system having a light source and a collimator lens, and fixedly disposed in the recording / reproducing device;
An objective lens, wherein the optical axis of the objective lens is supported perpendicular to a signal recording surface of the optical recording medium supported by the medium supporting means in the recording / reproducing apparatus; A parallel light beam emitted from the light source and emitted from the fixed optical system through the collimator lens is incident thereon, and the light beam is transmitted to the optical recording medium by the objective lens. A movable optical system for focusing light on the signal recording surface of
A concave lens and a convex lens, which are arranged on an optical path from the light source to the objective lens in order to correct spherical aberration generated in a transparent cover layer formed on a signal recording surface in the optical recording medium; A beam expander in which the distance between the convex lenses is variable;
Light detection means for detecting a light beam reflected by the signal recording surface of the light beam,
Signal processing means for performing signal processing on a light detection output from the light detection means,
The beam expander is characterized in that the relative position of the concave lens and the convex lens is adjusted in two directions orthogonal to the optical axis, thereby correcting aberrations caused by mounting errors of other optical elements. Recording and playback device.

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