JP2001160239A - Method for manufacturing optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup which may be easily assembled within a prescribed range of the angle errors of two lenses of the optical pickup of a two lens type of a shaft sliding type and an optical disk device using this optical pickup. SOLUTION: This optical pickup device 1 has an objective lens 9 for DVDs, an objective lens 8 for CDs and a sliding shaft 6 and a lens holder 7 designed to control the tracking and focusing of the respective lenses by the rotation around the sliding shaft 6 and the operation of the axial movement thereof. The individual objective lenses are fixed into guide holes (fixing parts) 78 and 79 formed in the prescribed positions of the lens holder by a sticking method using adhesion. As a result, the track errors and crosstalks are decreased and the stable reproduction of information from the individual optical disks is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc used for recording information on an optical information recording medium using a light beam and reproducing or erasing the already recorded information from the optical information recording medium. The present invention relates to a pickup and an optical disk device to which the optical pickup is applied.

[0002]

2. Description of the Related Art An optical disk apparatus used for optical information recording and reproduction using a light beam includes a laser light source for generating a light beam, a light beam generated from the light source being focused on a predetermined position on the optical disk, and An objective lens for collecting the light beam reflected by the optical disc, an optical element for guiding the light beam between the light source and the objective lens, and a predetermined signal output by photoelectrically converting the light beam transmitted by the optical element And a head drive mechanism for moving the objective lens in the radial direction of the optical disk. Incidentally, the objective lens generally has a thrust generating mechanism for moving the objective lens in a direction perpendicular to the surface including the recording layer of the optical disc and in the radial direction of the surface including the recording layer, and the objective lens is moved in the respective directions described above. An optical pickup is integrally formed with a movable spring member. The amount of movement that the propulsion force generating mechanism must generate to move the optical pickup in a direction perpendicular to the surface including the recording layer of the optical disc and in the radial direction of the surface including the recording layer is determined by the output from the photodetector. Specified by signal.

[0003] Today, music CD-type optical disks and DVD-type optical disks having a large storage capacity are mixed, so that each optical disk has two objective lenses having an optimum light-collecting capacity (NA). An optical pickup of a type in which an objective lens is switched according to the type of an optical disk has been put to practical use. As an example, two objective lenses for a DVD-type optical disc and a CD-type optical disc are provided in a shaft-sliding type lens holder, and the lens holder is rotated depending on the type of the optical disc, and one of the objective lenses is used. The choice is widespread.

In manufacturing an optical pickup having two objective lenses, a lens abutting surface is provided on a portion of the lens holder for holding each lens, and the lens abuts against each lens abutting surface. By utilizing the mechanical processing accuracy of the lens holder, the accuracy of the relative tilt angle of the two lenses is ensured.

[0005]

Heretofore, an objective lens for a DVD-type optical disk has been designed so that the angle between a perpendicular to the turntable surface (axial direction of the center of rotation of the optical disk holder) and the central axis of the lens has been known. The objective lens for CD-type optical discs is adjusted to be within a certain range and fixed to the lens holder by adhesive. The light-collecting property indicated by NA (numerical aperture) is smaller than that for DVD. It is assembled simply by fixing it to the provided lens holding part.

That is, the DVD objective lens is fixed at a predetermined angle after adjustment without depending on the accuracy of the shape of the lens holder. Adjustment is omitted because a lens having a relatively small degree and a small numerical aperture (NA) (the condensing property is not good when NA = 0.45 or less, but the degree of deterioration of the condensing property with respect to the inclination is small) can be used Have been.

However, when a CD-type optical disk is recordable (recording of CD-R, CD-RW),
It is necessary to use an objective lens that has better light-collecting properties (having a larger NA value) than in the case of reproduction-only. In this case, if the lens is fixed while relying on the machining accuracy of the lens abutting surface of the lens holder, There is a problem that the probability that the center axis of the lens does not fall within the reference angle with respect to the perpendicular to the turntable surface increases, and the yield when assembling the recording / reproducing apparatus decreases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical pickup which can easily assemble an angle error between two lenses within a predetermined range in a shaft-sliding two-lens type optical pickup, and an optical disk apparatus using the optical pickup. Is provided.

[0009]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above-mentioned problems. A first objective lens having a predetermined numerical aperture is fixed to a lens holder, and the first objective lens and the aperture are fixed to each other. The second objective lens having a different number is monitored by monitoring the difference in angle between the central axis in the optical path of the second objective lens and the central axis in the optical path of the first objective lens. And adjusting the relative tilt angle of the first and second lenses to be smaller than a predetermined value, and fixing them by bonding. To provide.

According to another aspect of the present invention, in an optical detection system having the same optical axis as a predetermined parallel light beam, a first objective lens having a predetermined numerical aperture and a second objective lens having a different numerical aperture from the first objective lens are provided. Are inserted on the parallel light beam in a predetermined order, and a beam spot that changes according to an angle between a central axis of any one of the objective lenses and the optical axis is imaged by an imaging unit. A method of manufacturing an optical pickup for an optical information recording / reproducing apparatus, wherein the tilt and the position of each objective lens are adjusted so that the state of a beam spot imaged at the optical axis coincides with the optical axis of the parallel light beam. Things.

Further, the present invention provides an optical detection system having the same optical axis as a predetermined parallel light beam, a first objective lens having a predetermined numerical aperture, and a second objective lens having a different numerical aperture from the first objective lens. The objective lens is inserted into the parallel light beam in a predetermined order, and a beam spot that changes according to the angle between the central axis of any one of the objective lenses and the optical axis is imaged by an imaging unit, and the objective lens is mounted on a lens holder. A horizontal moving member that fixes the center axis of the first objective lens inserted into the optical path of the parallel light beam and fixes the lens holder while monitoring the spot shape captured by the imaging unit. The horizontal position is set according to, and the relative angle between the lens holder and the optical axis of the imaging unit is adjusted to set the optical axis of the first objective lens and the optical axis of the parallel light beam at a predetermined angle. The lens holder is rotated around a rotation axis parallel to the central axis of the first objective lens, or the lens holder is translated in a direction perpendicular to the central axis of the first objective lens. By moving the fixing portion of the lens holder for holding the second objective lens into the optical path of the parallel light beam, inserting the second objective lens in the optical path of the parallel light beam, Controlling the angle of the second objective lens by independently changing the angle of the second objective lens within a predetermined range within the parallel light beam while monitoring the spot shape detected by the means; A method of manufacturing an optical pickup for an optical information recording / reproducing apparatus, wherein the objective lens is fixed to the lens holder.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical pickup according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram for explaining an optical disk apparatus using a switching type optical pickup of a shaft sliding type according to an embodiment of the present invention.

As shown in FIG. 1, an optical disk device 1
Is a spindle motor 3 fixed to the motor chassis 2 and rotating an optical disk (recording medium) D at a predetermined speed.
Then, an optical pickup 4 for irradiating a laser beam (light beam) on a recording surface (not shown) of the optical disk D and extracting a laser beam reflected on the recording surface, and moving the optical pickup 4 in a direction parallel to the recording surface of the optical disk D. It has a drive mechanism 5. The drive mechanism 5 is a part of the drive device 5, and is guided by a pair of guide rails 5a and 5b provided along the recording surface of the optical disk D and parallel to each other. Reciprocated in the radial direction.

At a predetermined position of the optical pickup 4, there is provided a lens holder 7 movably formed in each of a radial direction of the optical disk D and a direction orthogonal to the recording surface of the optical disk D. At a predetermined position of the lens holder 7, first and second objective lenses 8, 9 having different aperture ratios (NA) are provided.

In the optical pickup 4, a region covered by the lens holder 7 is provided with a semiconductor laser device described below with reference to FIG. Receiving the reflected laser beam from the recording surface of the optical disk D taken in by the objective lenses 8 and 9 via the optical element, and generating an electric signal corresponding to the light intensity of the received laser beam. An output photodetector and the like are provided.

FIG. 2 is a schematic diagram for explaining an example of the configuration of an optical pickup incorporated in the optical disk device shown in FIG.

As shown in FIG. 2, the lens holder 7
Has a cylindrical shape, and one end of the cylinder is formed on a flat surface 7a. The first and second objective lenses 8, 9 are provided on the plane 7a.
Are provided at a predetermined angle and a predetermined distance around the center of the plane 7a as an axis. The first objective lens 8 has an aperture ratio for a CD-R (CD-type recordable) disk (1.2 mm thick), and the second objective lens 9 has a DVD disk (thickness 0.6 mm). Further, the first and second objective lenses 8 and 9 (that is, the lens holder 7) are driven by the focus control 7f, the track control coil 7t, and a propulsion force provided by a rotating force generation mechanism including a magnet (not shown). Are located at first and second positions that can be switched to an operation position switched by a switching operation described below with the axis of the plane 7a as the center.

At positions parallel to the axis of the lens holder 7 and capable of reflecting the laser beam to the operating positions of the respective objective lenses 8 and 9, the first and second semiconductor laser elements described below are used. A mirror 11 is provided for guiding the laser beam to the objective lens (8 or 9) located in the above-mentioned working position.

At a position where a laser beam of a predetermined wavelength can be incident on the mirror 11, a first semiconductor laser element 12 for emitting a laser beam of a first wavelength and a second wavelength different from the first wavelength are provided. The second semiconductor laser element 13 for emitting the laser beam is provided. The wavelength of the laser beam emitted from the first semiconductor laser element 12 is DV
In order to reproduce information recorded on the D disk, for example, it is set to 650 nm. The wavelength of the laser beam emitted from the second semiconductor laser element 13 is CD
-Set to, for example, 780 nm for recording and reproducing information on the R disk.

A laser beam from each of the semiconductor laser elements 12 and 13 is provided between the mirror 11 and each of the semiconductor laser elements 12 and 13 and substantially reflects the entire amount of a laser beam having a specific wavelength. Are combined or separated by a dichroic mirror 14 that transmits substantially the entire amount.

Between the dichroic mirror 14 and the first semiconductor laser element 12, a collimating lens 15 for collimating a divergent laser beam from the semiconductor laser element 12 and a laser directed from the semiconductor laser element 12 to the optical disk D Isolator 1 for separating the laser beam reflected from the recording layer of the optical disc D from the laser beam based on the polarization direction of each laser beam.
6 are provided. At a position where the reflected laser beam separated by the isolator 16 is converged by the convergence of the collimator lens 15, the reflected laser beam is detected, photoelectrically converted, and reproduced as information recorded on a DVD disk. First photodetector 17
Is provided. A part between the collimator lens 15 and the isolator 16 detects a part of the reflected laser beam reflected by the optical disk D and monitors the light intensity of the laser beam emitted from the first semiconductor laser element 12. Two photodetectors 18 are provided.

Between the dichroic mirror 14 and the second semiconductor laser element 13, a collimating lens 19 for collimating the divergent laser beam from the semiconductor laser element 13 and a laser directed from the semiconductor laser element 13 to the optical disk D A half-mirror beam splitter 20 is provided which reflects the beam and the reflected laser beam reflected by the recording layer of the optical disc D at a predetermined ratio, and transmits and transmits the remainder to separate the beam. The reflected laser beam split by the half mirror beam splitter 20 is
At a position converged by the convergence of the collimator lens 19, the reflected laser beam is detected and photoelectrically converted, and the CD-R
The information recorded on the disc is reproduced, and the relative positional relationship between the recording layer on the recording surface of the optical disc D and the tracks (guide grooves) provided on the recording layer and the position of the objective lens is determined by a predetermined value. Photodetector 21 for generating a servo signal for setting within the condition of
Is provided. The second semiconductor laser device 13
A diffraction grating 22 for providing predetermined optical characteristics of a reflected laser beam reflected on the recording surface of the optical disc D and guided to the third photodetector 21 is provided between the half mirror beam splitter 20 and the half mirror beam splitter 20. .

Next, a procedure for fixing the first and second objective lenses to the lens holder of the optical pickup shown in FIG. 2 will be described.

As shown in FIGS. 1 and 2, the objective lens 9 for DVD, the objective lens 8 for CD, and the sliding shaft 6
Optical information recording / reproducing having a lens holder 7 which is designed to control the tracking and focusing of each lens 9 and 8 by the operation around the sliding shaft 6 and the movement in the axial direction (θ direction) Device (optical disk device)
In 1, the individual objective lenses 8 and 9 are attached to guide holes (fixed portions) 78 and 79 formed at predetermined positions of a lens holder 7 described below with reference to FIG. It is fixed by.

FIG. 3 is a schematic diagram illustrating the configuration of a lens holder used in the optical pickup shown in FIG.

As shown in FIG. 3, the lens holder 7
A CD lens fixing portion 78 to which the objective lens 8 for D is fixed, and a DVD provided at a predetermined angle, for example, 90 ° with respect to the sliding shaft 6 as a rotation center with respect to the CD lens fixing portion 78. A DVD lens fixing portion 79 to which the lens 9 is fixed is formed. The individual lenses 8, 9 are fixed to the corresponding fixing portions 78, 79 with a predetermined angle and positional relationship (relative position) by the method described below, and bonded. Note that the outer diameter of the objective lens 8 and the plane portion of the outer periphery of the lens 8 are used for positioning the objective lens 8 for CD and the fixing portion 78 of the lens holder 7. Also, each objective lens 8 (9)
The configuration is the same as the configuration described later with reference to FIG. 12 or 13, and the peripheral (flange) portion 80 (90) is provided integrally, and the outer diameter 81 of the flange 80 (90) is provided.
(91) is positioned with respect to the diameter of the fixing portion 78 (79) of the lens holder 7, and the flat portion 82 (92) of the flange 80 (90) is used to fix the fixing portion 78 of the lens holder 7.
The optical axis direction is determined by being brought into contact with the flat portion of (79).

More specifically, the measuring device 101 described below with reference to FIG.
By monitoring the state of the beam spot projected on the image sensor 144 in two stages by the monitor devices 145 and 146, the individual objective lenses 8 and 9 can be fixed at predetermined positions.

It should be noted that the beam spots projected on the monitor devices 145 and 146 may be displaced when the laser beam passing through the objective lens 8 and the optical axis of the objective lens 8 coincide with each other.
As shown in FIG. 6A, the central portion has a high luminance, and the central portion is surrounded by side lobes that are concentrically formed at substantially uniform intervals.

FIG. 4 is a schematic diagram for explaining the measuring device.

As shown in FIG. 4, the measuring device 101 includes a well-known manipulator 112, and a lens clamp mechanism 111 for positioning the objective lens 8 or 9 at an arbitrary position.
A gonio stage 121 configured to be movable independently of the lens clamp mechanism 111 and holding the lens holder 7 to which the objective lenses 9 and 8 are fixed at a predetermined position;
Convergence of the beam spot of the laser beam from the light source 131 given a predetermined convergence through the objective lens 9 or the objective lens 8 positioned at a predetermined position of the lens holder 7 by the lens clamp mechanism 111 and the gonio stage 121. An imaging device 14 for imaging a state and outputting the image to a monitor device
And 1.

The lens clamp mechanism 111 applies the manipulator 112 to the optical axis direction (Z-axis direction) of the objective lens 8 (9) and the first and second directions (X-axis direction) orthogonal to each other on a plane orthogonal to the optical axis direction. X stage 11 that can be independently moved in each of the directions (Y direction and Y axis direction).
3, having a Y stage 114 and a Z stage 115,
The objective lens held by the arm of the manipulator 112 is positioned at a predetermined angle (tilt) and a relative position with respect to the fixed portion 78 (79) of the lens holder 7 held by the gonio stage 121.

The gonio stage 121 holds the lens holder 7 (of the optical pickup 4) held by a lens holder holding mechanism (not shown) in the optical axis direction (Z axis direction).
First and second orthogonal to each other on a plane orthogonal to the axial direction
(In the X-axis direction and the Y-axis direction). After the lens holder 7 is set on a lens holder holding mechanism (not shown) by an operator in the assembly process of the optical pickup 4, the imaging device 141 Is moved to a predetermined position near the imaging region, that is, the manipulator 112. Thus, the lens holder 7 is positioned near the objective lens 9 or 8. The lens holder 7 is set on an adjustment table 122 provided near the light source 131 while being held by the lens holder holding mechanism.

The image pickup device 141 includes first and second objective lenses 142 and 143 provided with NAs corresponding to the objective lenses 8 and 9, respectively, and a light source passing through one of the objective lenses. The image sensor 144 includes an image sensor 144 that captures an image of the beam spot of the laser beam from the sensor 131, a low-resolution monitor device 145 that displays the beam spot captured by the image sensor 144, and a monitor device 146 that has the same high resolution. Note that the two objective lenses 142 and 143 are positioned by a rotating mechanism (revolver), which is not described in detail, at a measurement position where the laser beam from the light source 131 can be incident and when one of the lenses is located at the measurement position. To the retreat (non-measurement) position. Further, the shape of the beam spot guided by the image sensor 144 is changed depending on the angle between the central axis of the objective lens 8 and the optical axis.

Next, a procedure for fixing the first and second objective lenses to the lens holder using the measuring device shown in FIG. 4 will be described in detail.

The lens holder 7 held by the lens holder holding mechanism is set at a predetermined position on the adjustment table 122 of the gonio stage 121 of the measuring apparatus 101 shown in FIG.

In this state, the lens holder 7 is placed in a predetermined positional relationship with respect to the sliding shaft 6 as shown in FIG. Positioning is performed by adjusting the positional relationship such as (circumference).

Next, the manipulator 1 of the lens holder 7
The objective lens 8 for CD is set on the arm 12, and the beam spot of the laser beam from the light source 131 that has passed through one objective lens (here, the lens 142 for CD) of the imaging device 141 is imaged by the image sensor 144. I do.

At this time, the low-resolution monitor 145 visually confirms that the laser beam has passed through the objective lens 8, and switches to the high-resolution monitor 146.
As shown in (a), the objective lens 8 has a high brightness at the center and a beam spot can be monitored concentrically with side lobes generated at substantially uniform intervals around the center. The inclination and the position are set by the manipulator 112.

At this time, when the position and the inclination of the objective lens 8 are present, for example, the deformation of the central portion (deformation from a perfect circle to an ellipse) and the side lobe as shown in FIGS. Since the number and direction of the laser beam are biased, the tilt and position of the manipulator 112 are set to the optimum tilt and position while viewing the image on the high-resolution monitor 146, so that the beam spot of the laser beam passing through the objective lens 8 is adjusted. Can be easily located at a position where it is not deformed. FIG. 6 (b) shows the direction in which the objective lens 8 is parallel to the sliding shaft 6 (tangential (Ta)
n) direction) for 10 minutes (', ie, 10/60)
FIG. 6C shows a state in which the objective lens 8 is tilted for 20 minutes in a direction parallel to the sliding shaft 6, and FIG.
Indicates a state in which the objective lens 8 is inclined for 30 minutes in a direction parallel to the sliding shaft 6. Also, FIG.
10 minutes (10/6) with respect to the direction (radial (Rad) direction) in which the objective lens 8 rotates about the sliding shaft 6 as an axis.
FIG. 6F shows a state in which the objective lens 8 is tilted for 20 minutes in a direction in which the objective lens 8 rotates about the sliding shaft 6 as an axis. FIG. Each of them shows a state of being inclined for 30 minutes in a direction rotated about the dynamic shaft 6 as an axis.

In this way, the positions of the objective lens 8 and the lens holder 7 are determined, and then the monitor light having the same wavelength as that used for reproducing the CD-type optical disc is transmitted.
Irradiate the objective lens 8 for CD in substantially the same direction and accuracy as during reproduction.

This monitor light is guided to the image pickup device 144 by the corresponding objective lens 142 of the image pickup device 141 to take an image, and the shape of the obtained beam spot is monitored. For example, when the intensity of the monitor light incident on the objective lens 8 is uniform and the central axis of the lens 8 coincides with the optical axis, the spot shape (intensity distribution) becomes centrally symmetric as shown in FIG. Thus, side lobes are generated concentrically with the center. When the central axis of the monitor light incident on the objective lens 8 is tilted with respect to the optical axis, as shown in FIGS. 6B to 6G, the symmetry of the spot shape is changed according to the tilt. Collapses.

Accordingly, the image pickup device 144 of the image pickup device 141
By monitoring the shape of the spot projected on the object, the magnitude and direction of the inclination of the objective lens 8 with respect to the monitor light can be detected.

Next, the adjustment table 12 of the gonio stage 121
The angle of the lens holder holding mechanism holding the lens holder 7 is adjusted by adjusting the inclination of the spot shape of the spot shape imaged by the imaging device 144 of the imaging device 141 for fixing the objective lens 8 described above. Adjust by the method of monitoring symmetry.

Subsequently, the lens holder 7 is rotated about the slide shaft 6 as a center axis, and the lens fixing portion 79 for holding the objective lens 9 for DVD is positioned so as to enter the light beam of the monitor light beam, and is fixed. I do. At this time, the wavelength of the monitor light beam used for the monitor is switched to the parallel light having the same wavelength as that used for reproducing the optical disk for DVD, and the optical axis is used for positioning the objective lens 8 for CD. The optical axis of the monitor light is adjusted in advance so as to coincide with a predetermined accuracy equal to (or higher than) the monitor light. The objective lens of the monitor system for monitoring the spot shape is also a DVD measurement objective lens (the objective lens of the imaging device 141 of the measuring device 101 is switched from the CD objective lens 142 to the DVD objective lens 143). .

More specifically, the lens holder 7 is positioned at a predetermined position on the adjustment table 122 of the gonio stage 121, and the objective lens 9 for DVD is manipulated using the manipulator 112.
As shown in FIG. 7A, the DVD of the lens holder 7 is
The objective lens 1 is positioned on the axis of the
While monitoring the spot shape projected on the image sensor 144 after passing through the image sensor 43, the manipulator 112 and the gonio stage 121 use a method perpendicular to the optical axis of the monitor light (X−
The object lens 9 is moved in parallel in the Y direction) and the optical axis direction (Z direction), and the tilt in the optical axis direction is adjusted to position the objective lens 9 in the light beam of the monitor light beam. Closed (at this time, even if a part of the DVD lens 9 comes into contact with the fixing portion 79 of the lens holder 7, the D
It is only necessary to maintain the angle of the VD lens).

In this state, the DVD lens 9 is adhered and fixed to the lens 9 fixing portion 79 of the lens holder 7 using an ultraviolet curable adhesive (see FIG. 7B).

The above-described device for monitoring the spot shape (measuring device 101) is commercially available under the name of "optical pickup spot evaluation device" or the like. The shape of the spot that has converged (on the surface opposite to the substrate) through a substrate having the same optical characteristics and thickness as the substrate of the optical disk (light on a plane perpendicular to the optical axis of the measurement system at the focal point) (Intensity distribution) can be monitored.

The optical pickup spot evaluation apparatus is substantially the same as a microscope, but has the same optical characteristics and thickness as the optical disk substrate between the objective lens of the measurement system and the object (optical head). The difference is that the transparent substrate is installed (can be installed).

In the measuring apparatus 101, an objective (measurement) lens having a NA (higher) than the NA of the objective lens to be measured is usually used. In other words, when the measurement lens has a smaller (lower) NA than the object, a part of the convergent light from the object lens, which is the object, is cut (in a state where the diaphragm is closed), and the objective lens, which is the measurement object, This is because the shape of the focused spot cannot be correctly observed.

Incidentally, the NA of the DVD objective lens is usually 0.5 or more, and the NA of the objective lens (microscope objective lens) of the evaluation apparatus 101 is preferably 0.55 or more. As the size increases, the types of commercially available objective lenses for microscopes having a long focal length decrease and become expensive (although expensive ones having a NA of 0.55 or more and a focal length exceeding 5 mm are referred to as "long-acting"). Marketed under the name of "distance objective lens").

It is desirable that the focal length of the microscope objective lens of the evaluation apparatus 101 according to the embodiment of the present invention be 5 mm or more even if the cost is somewhat high. The reason is that, when monitoring the spot formed by the objective lens to be measured, the objective lens of the evaluation apparatus 101 and the objective lens (DVD lens) of the optical pickup 4 are set to about the "sum" of the focal lengths of the two. If the distance is short, there is a risk that the transparent substrate having the same thickness as the optical disk substrate inserted therebetween and the DVD lens 9 or the manipulator holding the DVD lens 9 may interfere with each other. is there.

In the above-described embodiment, as shown in FIG. 7A, when the angle of the DVD lens 9 is adjusted, the adjustment is performed without bringing the lens 9 into contact with the lens holder 7. .

FIGS. 8 and 9 show FIGS. 7 (a) and 7
It is the schematic explaining the other embodiment for fixing the lens for DVD shown to (b) to a lens holder.

As shown in FIG. 8, when the DVD objective lens 9 is fixed to the lens holder 7, the surface of the DVD lens 9 which comes into contact with the fixing portion 79 of the lens holder 7 is close to the spherical surface. It can be used to adjust the tilt. That is, since the surface of the objective lens 9 on the lens holder 7 side is substantially spherical, the inner surface (inner side) of the fixing portion 79 of the lens holder 7 in the axial direction is a conical surface, so that the weight of the lens 9 is reduced. By the centering action by the spherical surface, the lens 9 can be arranged on the fixing portion 79 of the lens holder 7 so that the optical axis passes through the center.

As shown in FIG. 9, a curved surface portion 99 is provided on the outer surface of the DVD lens 9 for the purpose of angle adjustment (alignment), not for optical purposes. The centering effect by the fixing portion 79 may be used.

More specifically, as shown in FIG. 8, a circular opening hole (inner diameter) 79-1 (diameter of the inner surface) serving as a diaphragm provided in the fixing portion 79 of the lens holder 7 is formed. The central axis is generally designed to be the same as the optical axis of the monitor light and the optical axis of the laser beam at the time of recording / reproducing.) The optical effective diameter of the objective lens 9 (the diameter at which the light can be narrowed) is generally ), The curved surface of the lens 9 is brought into contact with the edge of the opening hole 79-1, and
The lens 9 is pressed into the lens holder 7 and the lens 9 is opened.
By moving the DVD lens 9 in the X-Y direction on a plane perpendicular to the central axis of 9-1, the angle of the DVD lens 9 (the angle formed by the central axis of the lens and the central axis of the aperture) is adjusted.

At this time, the lens 9 is pressed against the fixing portion 79 of the lens holder 7 by the lens 9 and the lens holder 7.
It is desirable that the amount of force be small enough that smooth movement is not hindered by the friction of the lens or that the lens 9, lens holder 7, adjustment mechanism, and the like are not deformed.

In order to prevent the objective lens 9 from being unnecessarily displaced in the X and Y directions, as shown in FIG.
By providing a concentric cylindrical stopper portion 79-2 in the axial direction of the fixing portion 79 of the lens holder 7 shown in FIG. 3, workability is improved.

When the tilt of the objective lens 9 is adjusted by this method shown in FIG.
Since "XYZ adjustment of lens" is performed, it is not necessary to adjust XYZ again after adjusting the tilt, so that the working efficiency is improved as compared with the method described above.

FIG. 11 is a schematic diagram for explaining another embodiment of the method of fixing the DVD objective lens shown in FIG. 8 to the fixing portion of the lens holder.

As shown in FIG. 11, D of the lens holder 7
Opening hole 79-1 of lens fixing portion 79 for VD and lens 9
Is in contact with a slope 79-3 such as a dish fir (taper), a triangular pyramid or a quadrangular pyramid, and the slope 79-3 supports the outer periphery (outer edge) of the lens 9.

More specifically, the lens 9 is pressed against the inclined surface 79-3 (the lens holder 7) while the lens 9 is supported by the inclined surface 79-3, and the lens 9 is placed in a plane perpendicular to the center axis of the opening hole 79-1. , The angle of the lens 9 (the angle between the central axis of the lens and the central axis of the aperture) can be adjusted. At this time, the force for pressing the lens 9 against the lens holder 7 is the same as that of the lens 9 and the lens holder 7.
It is desirable that the amount is small enough that the smooth movement of the lens 9 is not hindered by the friction of the lens 9 or that the lens 9, the lens holder 7 and the adjustment mechanism are not deformed.

At this time, a cylindrical stopper 79-for preventing the lens 9 from being displaced more than necessary in the XY directions.
By providing the lens holder 2 in the lens holder 7, workability can be improved.

FIG. 12 shows the DV shown in FIG. 8 or FIG.
FIG. 11 is a schematic diagram illustrating another embodiment of a fixing portion of a lens holder that holds an objective lens for D.

As shown in FIG. 12, the lens holder 7
Cylindrical stopper 79-of the DVD lens fixing portion 79.
2 is provided with a plurality of notches 79-4 for inserting the arm of the manipulator 112. When the notch 79-4 has a structure in which the inclined surface 79-3 is provided in the opening 79-1 of the lens fixing portion 79 of the lens holder 7, the objective lens 9 can be used as the cylindrical stopper 79 of the fixing portion 79. 12, the arm of the manipulator 112 is inserted from the left and right in the example shown in FIG. 12 (the arm of the manipulator 112 is released after the lens 9 is fixed to the lens holder 7). It is. In addition, the number of the notches 79-4 is
It is desirable to provide two or more arms so that the twelve arms can be inserted (removable) from two or more directions on the side surface of the lens 9.

With this structure, the NA of the DVD objective lens 9 and the NA of the DVD objective lens 113 of the imaging device 111 of the measuring device 101 are both relatively large, and the beam spot is monitored by the imaging device 111 while monitoring the beam spot. When the distance approaches 10 mm or less, the arm of the manipulator 112 for adjusting the tilt angle of the lens 9 can be easily inserted and removed from the side of the lens 9 even if a transparent substrate equivalent to a DVD disk is inserted. And Even when the tilt of the objective lens 9 is adjusted by this method, the tilt adjustment of the lens 9 is “XYZ adjustment”. Therefore, after adjusting the tilt, XYZ is adjusted again. Eliminates the need.

Further, apart from the configuration shown in FIG. 12, the objective lens 113 of the measuring device 101 and the DVD objective lens 9 are connected to each other by, for example, increasing the diameter of the DVD objective lens 113 of the measuring device 101. 8 or 11, the inclination of the objective lens 9 is adjusted by applying a force to the outer peripheral portion (outer edge) of the objective lens 9 in a direction parallel to the optical axis. It is good also as a mechanism which performs.

According to the method shown in FIGS. 8, 11 and 12, for example, the fixing portion 79 of the lens holder 7 is compared with the method shown in FIGS. 7 (a) and 7 (b). Since the angle (inclination) of the inclined surface 79-2 can be appropriately selected, the inclination change amount α (X
Objective lens 9 for DVD for unit displacement in Y direction
(The amount of change in inclination) can be appropriately selected according to the workability.
Since the VD lens 9 is tilted excessively, adjustment becomes difficult. In the opposite case, the tilt of the DVD lens 9 becomes insensitive to the XY displacement, and the adjustment takes more time than necessary.)

The objective lens 9 for adjusting the tilt angle by the manipulator 112 does not need to be one-piece as described below with reference to FIG. 13 or FIG.
A lens composed of a plurality of parts may be used.

FIG. 13 is a schematic diagram illustrating a first embodiment of an objective lens composed of two or more components.

As shown in FIG. 13, the objective lens 9 for DVD is joined to a flat glass plate 9a from above and below with two members (lens portions) 9b and 9c having optical characteristics aligned with the center. It was done. FIG.
4 (second embodiment), as shown in FIG.
Alternatively, a ring 9d having a flange-shaped flat portion may be integrally formed.

As described above, according to the present invention,
In an axis-sliding type optical pickup, the relative inclination angle (the amount of inclination with respect to each axis center) between an objective lens having an NA for a DVD type disk and two different objective lenses having an NA for a CD type disk is determined. In the range. As a result, track errors and crosstalk are reduced, and information can be stably reproduced from individual optical disks. In addition, in fixing the objective lens to a lens holder that requires high positional accuracy in order to record information on a CD type optical disk, the yield is improved, and the cost of the entire optical pickup is reduced.

By setting the two objective lenses at an angle within a predetermined range with respect to the sliding axis of the lens holder,
Since the operation amount of the servo system is reduced, the convergence time (time required for positioning the objective lens at a predetermined position) during focus control and track control is reduced, and the seek speed is improved.

[0075]

As described above, the optical pickup assembled by the method of manufacturing an optical pickup according to the present invention is different from an objective lens having an NA for a DVD type disc and an NA having an NA for a CD type disc. The relative tilt angle between the two objective lenses can be suppressed within a predetermined range.

As a result, in fixing the objective lens to the lens holder, the yield is improved, and the cost of the entire optical pickup is reduced. Further, a servo system for positioning the objective lens at a predetermined position can be simplified.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an optical disc device in which an optical pickup according to an embodiment of the present invention is incorporated.

FIG. 2 is a schematic diagram for explaining elements constituting an optical pickup of the optical disk device shown in FIG. 1;

FIG. 3 is a schematic diagram showing a lens holder of the optical pickup shown in FIG. 2;

FIG. 4 is a schematic diagram illustrating a measuring device for fixing an objective lens to the lens holder illustrated in FIG. 3;

FIG. 5 is a schematic diagram illustrating the tilt and rotation of the optical pickup shown in FIG. 2;

FIG. 6 is a schematic diagram illustrating an example of a beam spot shape imaged by an image sensor of the measurement device illustrated in FIG. 4;

7 is a schematic diagram illustrating a method of fixing a second objective lens to a lens holder of the optical pickup shown in FIG.

8 is a schematic diagram illustrating an example of a configuration of a lens holding unit of the lens holder illustrated in FIG.

9 is a schematic diagram illustrating an example of a configuration of a lens holding unit of the lens holder illustrated in FIG.

10 is a schematic diagram illustrating an example of a configuration of a lens holding unit of the lens holder illustrated in FIG.

11 is a schematic diagram illustrating an example of a configuration of a lens holding unit of the lens holder illustrated in FIG.

FIG. 12 is a schematic diagram illustrating an example of a configuration of a lens holding unit of the lens holder illustrated in FIG.

FIG. 13 is a schematic diagram illustrating an example of a configuration of an objective lens used in the optical pickup illustrated in FIG.

FIG. 14 is a schematic diagram illustrating an example of a configuration of an objective lens used in the optical pickup shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical disk apparatus, 2 ... Motor chassis, 3 ... Spindle motor, 4 ... Optical pickup, 7 ... Lens holder, 8 ... Objective lens (for CD), 9 ... Objective lens (for DVD) 78 78 Lens fixing part for CD 79 Lens fixing part for DVD

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Shinoda 70 Yanagicho, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Yanagicho Plant (72) Inventor Ikuo Kasuga 5329 Shimosuwa-cho, Suwa-gun, Nagano Prefecture Sankyo Seiki Seisakusho Co., Ltd. (72) Inventor Toshihiko Okina 5329 Shimosuwa Town, Suwa County, Nagano Prefecture Inside Sankyo Seiki Seisakusho Co., Ltd. (72) Inventor Katsushige Yanagisawa 5329 Shimo Suwa Town, Suwa County, Nagano Prefecture Sankyo Seiki Seisakusho Co., Ltd. (72) Invention Person Toru Hotta 5329 Shimosuwa-cho, Suwa-gun, Nagano Prefecture F-term in Sankyo Seiki Seisakusho Co., Ltd. 5D119 AA38 BA01 EB03 JA43 JC03 JC05 JC07 NA01 PA04 PA05

Claims (9)

[Claims] 1. A first objective lens having a predetermined numerical aperture is fixed to a lens holder, and a second objective lens having a different numerical aperture from the first objective lens is provided in an optical path of the second objective lens. The angle of the second objective lens is adjusted by monitoring the difference in angle between the central axis and the central axis in the optical path of the first objective lens, and the relative inclination angle of the first and second lenses is predetermined. A method for manufacturing an optical pickup for an optical information recording / reproducing device, wherein the optical pickup is adjusted so as to be smaller than the value of (1) and is fixed by bonding. 2. An optical detection system having the same optical axis as a predetermined parallel light beam, a first objective lens having a predetermined numerical aperture, and a second objective lens having a different numerical aperture from the first objective lens. Are inserted in the predetermined order in the parallel light beam, a beam spot that changes according to the angle between the central axis of any one of the objective lenses and the optical axis is imaged by the imaging unit, and is imaged by the imaging unit. A method of manufacturing an optical pickup for an optical information recording / reproducing apparatus, wherein the tilt and the position of each objective lens are adjusted so that the state of the beam spot coincides with the optical axis of the parallel light beam. 3. An optical detection system having the same optical axis as a predetermined parallel light beam, a first objective lens having a predetermined numerical aperture, and a second objective lens having a different numerical aperture from the first objective lens. Are inserted on the parallel light beam in a predetermined order, and a beam spot that changes according to an angle between the central axis of any one of the objective lenses and the optical axis is imaged by an imaging unit, and is fixed to a lens holder. The central axis of the first objective lens inserted in the optical path of the parallel light beam is moved in the horizontal direction by a horizontal moving member fixing the lens holder while monitoring the spot shape imaged by the imaging means. And adjusting the relative angle of the imaging means with the lens holder with respect to the optical axis so that the optical axis of the first objective lens coincides with the optical axis of the parallel light beam with a predetermined accuracy. , By rotating the lens holder around a rotation axis parallel to the central axis of the first objective lens, or by translating the lens holder in a direction perpendicular to the central axis of the first objective lens, A fixing portion of the lens holder for holding a second objective lens is moved into an optical path of the parallel light beam, and the second objective lens is inserted into an optical path of the parallel light beam, and is detected by the imaging unit. While monitoring the spot shape, independently adjust the angle of the second objective lens by changing the angle of the second objective lens within a predetermined range within the parallel light beam. A method for manufacturing an optical pickup for an optical information recording / reproducing device, wherein the optical pickup is fixed to a lens holder. 4. The method according to claim 1, wherein the second objective lens and the lens holder are not in contact with each other, or are in contact with only one point, and the second objective lens is fixed to the lens holder with an adhesive. A method for manufacturing an optical pickup according to claim 1. 5. A contact portion of said lens holder with said second objective lens and said second objective lens are contacted by a spherical portion of said second objective lens, and said second objective lens is placed in said lens holder. The relative angle between the central axis of the second objective lens and the optical axis is controlled by moving the optical axis relative to the lens holder in a direction perpendicular to the optical axis while pressing against the optical axis. 3. The method for manufacturing an optical pickup according to item 2. 6. A contact portion of the lens holder with the second objective lens has a structure in which an outer diameter portion of the second objective lens is received on an inclined surface, and the second objective lens is connected to the lens. The relative angle between the central axis of the second objective lens and the optical axis is controlled by relatively moving the lens holder in a direction perpendicular to the optical axis while pressing against the holder. The method for manufacturing an optical pickup according to claim 2. 7. An optical pickup according to claim 4, wherein a part of the outer peripheral surface of said lens holder is open compared to other areas. Method. 8. The method for manufacturing an optical pickup according to claim 4, wherein said lens holder has a barrier structure for preventing said second objective lens from being displaced more than necessary. 9. A space in which a tool capable of adjusting an inclination angle of the second objective lens is provided near a contact portion of the lens holder with the second objective lens. 9. The method for manufacturing an optical pickup according to claim 8, wherein: