JP2004185740A - Optical head device - Google Patents

Abstract

An object of the present invention is to make it possible to reliably perform Ta shift adjustment without causing a height change in a slide base when adjusting a Ta shift of a slide base on which an optical element group is mounted.
A slide base (10) is always in contact with a main guide bearing holding member (20), and its position can be adjusted in a direction perpendicular to the optical disk surface. By attaching a position adjusting member 70 for giving a displacement in a direction parallel to the optical disk surface and orthogonal to the optical head scanning direction to the slide base 10, and adjusting the position of the position adjusting member 70 in a direction orthogonal to the optical disk surface. Only the relative positional relationship between the slide base 10 and the main guide bearing holding member 20 in a direction parallel to the optical disk surface and orthogonal to the optical head scanning direction is configured to be adjustable.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a disk recording / reproducing apparatus or a disk using a disk for optically reproducing, such as a CD (Compact Disc), a DVD (Digital Versatile Disc), an MD (Mini Disc), an MO (Magnetic Optical Disc), or the like. The present invention relates to an optical head device mounted on a reproducing device. In this specification, a disc that performs optical reproduction is referred to as an optical disc including an MO.
[0002]
[Prior art]
In an optical head of an optical disk device using an optical disk on which high-density recording is performed as a recording medium, it is necessary to perform a work process called skew adjustment in an assembling process so that an optical axis of an objective lens is orthogonal to a disk surface. is there. The skew adjustment includes a radial skew adjustment (Ra skew adjustment) in a radial direction (hereinafter referred to as Ra direction) in which the optical head scans the optical disk, and a direction orthogonal to the Ra direction in which the optical head scans the optical disk on the disk surface. (Hereinafter referred to as Ta direction) tangential skew adjustment (Ta skew adjustment).
[0003]
By the way, when the data area advances toward the inner circumference of the disk in order to increase the recording capacity in addition to the high-density recording, the recording is continuously performed in a concentric or spiral manner called pits on which data is recorded on the disk surface. The trajectory of the section (hereinafter referred to as a track) has a higher curvature of the track in a microscopic range near the beam spot of the optical head toward the center of the disk. In some cases, a displacement may occur in the Ta direction, and in the case where a three-beam method or the like is used as the tracking method, a phenomenon that tracking servo becomes difficult or impossible, particularly near the inner periphery of the disk, is caused. It becomes remarkable.
[0004]
Therefore, a method of correcting the deviation in the Ta direction by adjusting the rotation angle of a diffraction grating integrated with the light source unit or disposed immediately after the light source inside the optical head (optical head device) can be considered. Usually, since the optical head is incorporated into the mechanical unit to which the spindle motor belongs in a state where the optical system has been adjusted, the optical head is assembled into the mechanical unit after the optical head is incorporated into the mechanical unit in the mass production process and the structure of the disk mechanical unit. It is difficult to adjust the rotation angle of the diffraction grating.
[0005]
An example of a conventional optical head device will be described below with reference to FIGS. 5A is a perspective view of the conventional optical head device as viewed from above, FIG. 5B is a perspective view of the conventional optical head device as viewed from above, and FIG. 6A is a bottom view of the conventional optical head device. 6 (b) is a cross-sectional view taken along line AA of FIG. 6 (a), and FIG. 6 (c) is a cross-sectional view taken along line BB of FIG. 6 (a). is there. 5 and 6, an adjustment jig used for correcting a deviation in the Ta direction is also illustrated.
[0006]
5 and 6, reference numeral 110 denotes a slide base, 120 denotes a main guide bearing holding member, 50 denotes a main guide shaft, 60 denotes a sub guide shaft, and 130 denotes an adjustment jig. The slide base 110 and the main guide bearing holding member 120 are integrally assembled. The main guide shaft 50 whose both ends are held by the mechanical unit is inserted into the main guide bearing holding member 120. The slide base 110 and the main guide bearing holding member 120 are integrally transported along the two guide shafts 50 and 60 by inserting the sub guide shaft 50 having both ends held therein. . On the slide base 110, a beam light source and an optical element group 30 such as a light receiving element for detecting return light, and a lens actuator 40 of an objective lens 31 in the optical element group 30 are mounted.
[0007]
The slide base 110 is formed by pressing a metal plate. The slide base 110 has a notch 110a (FIG. 5A) for supporting the sub guide shaft 60, and a main guide bearing. A pair of elongated holes 110b, 110b (FIG. 6 (a)), which are inserted so that screws 140 (FIG. 5 (b)) screwed into the holding member 120 do not hinder the adjustment of the Ta shift. ) And the rib-shaped guide portion of the main guide bearing holding member 120 is fitted, and the guide hole portion 110c (FIG. 5 (b) in FIG. 6) and the eccentric portion 130b (FIG. 5A) of the adjustment jig 130 is fitted, and the adjustment jig 130 is rotated so that the slide base 110 is attached to the main guide bearing holding member 120. Then, the main guide shaft 50 is loosely inserted into the adjustment holes 110d (FIGS. 5B and 6A) for moving only in the Ta direction, and the main guide shaft 50 interferes with the slide base 110. A pair of holes 110e, 110e (FIG. 5) are formed so as not to hinder the Ta shift adjustment.
[0008]
The main guide bearing holding member 120 is made of a molded product other than sheet metal, such as casting or injection molding, and a metal bearing (not shown) made of a pair of sintered metals according to a sliding state with the main guide shaft 50. And the main guide shaft 50 is inserted through the metal bearing. The main guide bearing holding member 120 has a pair of screw holes 120a, 120a2 (see FIG. 5B) for screwing and fastening a screw 140 (FIG. 5B) for fixing the slide base 110 to the main guide bearing holding member 120. 5A and FIG. 6A), the slide base 110 is moved only in the Ta direction with respect to the main guide bearing holding member 20 by fitting into the guide hole 110c formed in the slide base 110. The rib-shaped guide portions 120b, 120b ((b) in FIG. 5, (a), (b) in FIG. 6) for fitting, and the tip portion 130a ((a) in FIG. 5) of the adjustment jig 130 are fitted. , A jig fitting hole 120c (FIG. 5 (b), FIG. 6 (a)) serving as a rotation center support portion of the adjustment jig 130 which rotates when performing the Ta shift adjustment.
[0009]
Next, a description will be given of a Ta shift adjusting operation for adjusting the position by moving the slide base 110 in parallel with the main guide bearing holding member 120 in the Ta direction. Here, it is assumed that the optical disk device employs a tracking servo system based on a three-beam method.
[0010]
Assuming that the focus servo adjustment has been completed, an optical disk (not shown) is mounted, and a spindle motor (not shown) is driven to rotate the optical disk. Then, the signal recording surface of the optical disk is irradiated with a light beam, the light beam is reflected by the signal recording surface, and the return light is detected by a light receiving element. This is converted into an electric signal to synthesize a tracking sub-beam signal. Observe the Lissajous waveform. In the Ta shift adjustment, the position of the slide base 110 with respect to the main guide bearing holding member 120 in the Ta direction is adjusted using the eccentric jig 130 so that the aspect ratio of the Lissajous waveform falls within a specified range. At the time of this Ta shift adjustment, the screw 140 is loosened so that the displacement of the slide base 110 with respect to the main guide bearing holding member 120 in the Ta direction can be adjusted (FIG. 6B). , 110b and 120a are omitted, but the screw 140 is loosened during the Ta shift adjustment).
[0011]
[Problems to be solved by the invention]
In the above-described conventional apparatus, the skew adjustment work and the Ta direction shift adjustment (hereinafter referred to as Ta shift adjustment) work have been required for the same product because of mass production considerations. The skew adjustment and the Ta shift adjustment are not performed in a systematic manner, or the WD is determined by the NA of the objective lens that has a large influence on the Ta shift so that any of the above adjustments is unnecessary. The specifications are such that a margin is secured for the focal length between the disk reflecting surface and the objective lens of the optical head, the minimum length of the recording pit, the track pitch, the innermost diameter, and the like.
[0012]
However, in view of the demand for higher-density, larger-capacity, smaller and lighter-weight disc products, it is anticipated that the Ta-direction deviation adjustment work will be an inevitable adjustment work that cannot be omitted. Is done.
[0013]
However, the above-described conventional Ta-direction deviation adjustment involves loosening the screw 140 for fixing the slide base 110 and the guide bearing holding unit 120, and thus the height of the slide base 110 fluctuates. . However, at the time of adjusting the deviation in the Ta direction, since the work is performed while irradiating the signal recording surface of the optical disk with the light beam and detecting the return light reflected on the signal recording surface of the light beam, the return due to the height fluctuation of the slide base is performed. Light detection fluctuations must be suppressed as much as possible.
[0014]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to reliably perform Ta shift adjustment without causing a height variation in a slide base when Ta shift is adjusted. .
[0015]
[Means for Solving the Problems]
The present invention achieves the above-mentioned object,
A slide base on which an optical element group and a lens actuator of an objective lens in the optical element group are mounted; and a main guide bearing holding member which is inserted and guided by a main guide shaft and to which the slide base is attached so as to be adjustable in position. An optical head device in which the slide base and the main guide bearing holding member are integrally scanned in the radial direction of the optical disc;
The slide base is always in contact with the main guide bearing holding member, and the position of the slide base can be adjusted in a direction perpendicular to the optical disk surface. On the other hand, by attaching a position adjusting member that gives a displacement in a direction parallel to the optical disk surface and orthogonal to the optical head scanning direction,
By adjusting the position of the position adjusting member in a direction perpendicular to the optical disk surface, only the relative positional relationship between the slide base and the main guide bearing holding member in a direction parallel to the optical disk surface and orthogonal to the optical head scanning direction is obtained. Are configured to be adjustable.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
1 to 4 relate to an embodiment of the present invention. FIG. 1A is an overhead perspective view of the optical head device of the present embodiment, and FIG. 1B is a perspective view of the optical head device of the present embodiment. FIG. 2A is a plan view of the optical head device of the present embodiment, FIG. 2B is a cross-sectional view taken along line AA of FIG. 2A, and FIG. 2C is a sectional view taken along line BB of FIG. 2A, FIG. 2D is a sectional view taken along line CC of FIG. 2A, and FIG. 4 (d) is an enlarged view of a main part, and FIGS. 4 (a) and 4 (b) are explanatory views showing the state of Ta displacement of the slide base in the optical head device of the present embodiment. 1 to 3 also illustrate an adjustment screw driver used for correcting a deviation in the Ta direction, and FIG. 4 also illustrates an optical disk and a spindle motor.
[0018]
1 to 4, 10 is a slide base, 20 is a main guide bearing holding member, 30 is an optical element group, 40 is a lens actuator, 50 is a main guide shaft, 60 is a sub guide shaft, 70 is a position adjusting member, 75 Denotes an adjustment screw, 80 denotes an adjustment screw driver, 90 denotes an optical disk, and 100 denotes a spindle motor.
[0019]
The slide base 10, the main guide bearing holding member 20, and the position adjusting member 70 are assembled integrally, and the main guide shaft 50, whose both ends are held by a mechanical unit (not shown), is inserted into the main guide bearing holding member 20. Then, a sub guide shaft 50 whose both ends are held by a mechanical unit (not shown) is inserted into the slide base 10, and the slide base 10, the main guide bearing holding member 20, and the position adjusting member 70 are integrated. Thus, the optical disk is transported along the two guide shafts 50 and 60 (the optical disk is transported (scanned) along the radial direction of the optical disk). The slide base 10 is mounted with an optical element group 30 such as a beam light source and a light receiving element for detecting return light, and a lens actuator 40 of an objective lens 31 in the optical element group 30, and is included in the optical element group 30. Each of the optical elements to be formed is attached to the slide base 10 directly or via a holding member (not shown) by an adhesive or a screw by each positioning shape formed on the slide base 10 or by a positioning jig (not shown). It is attached by a stop.
[0020]
The slide base 10 is formed by pressing a metal plate. The slide base 10 has a notch 10a (FIG. 1A) for supporting the sub guide shaft 60, and a main guide shaft. The main guide shaft 50 is screwed into a pair of holes 10b and 10b (FIG. 1) drilled so that the main guide shaft 50 does not interfere with the slide base 10 and hinder the Ta shift adjustment. And a leaf spring 10d (FIGS. 1 to 4) for elastically holding the main guide bearing holding member 20 with the position adjusting member 70. A pair of guide notches 10e and 10e (FIG. 1) for guiding the position adjusting member 70 so as to be able to move in parallel only in a direction perpendicular to the optical disk surface is formed.
[0021]
The main guide bearing holding member 20 is made of a molded product other than sheet metal, such as casting or injection molding, and is press-fitted with a pair of sintered metal bearings 55 (FIG. 2B). The main guide shaft 50 is inserted through the main guide shaft 50. The main guide bearing holding member 20 has a substantially cylindrical shape with a part cut away, and a portion where the leaf spring portion 10d of the slide base 10 contacts and a portion where the later-described tapered portion 70b of the adjustment member 70 contacts are arc-shaped. Further, the portion of the slide base 10 that comes into contact with the main surface (the surface parallel to the optical disk surface) is a flat surface (see the cross section of the main guide bearing holding member 20 in FIG. 3).
[0022]
The position adjusting member 70 is made of a molded product other than sheet metal, such as casting or injection molding. The position adjusting member 70 has a pair of protrusions 70a which are engaged with the guide notches 10e of the slide base 10. , 70a (FIG. 1), a tapered portion 70b (FIG. 3) that comes into contact with the main guide bearing holding member 20, and a screw hole 70c (FIG. 3) into which the screw portion of the adjusting screw 75 is screwed. .
[0023]
In the above-described configuration, the main guide bearing holding member 20 is always in close contact with the tapered portion 70b of the adjusting member 70 by the component force in the Ta direction (horizontal component force) by the plate spring portion 10d of the slide base 10. , And is pressed against the main surface of the slide base 10 by a component force in the direction perpendicular to the optical disk surface (vertical component force) by the leaf spring portion 10d so as to be always in close contact with the main surface of the slide base 10. Have been. The position adjusting member 70 to which the adjusting screw 75 is screwed can be displaced in a direction orthogonal to the optical disk surface by rotating the adjusting screw 75. With this configuration, the main surface of the slide base 10 is always in close contact with the main guide bearing holding member 20, so that the adjusting screw 75 is rotated to move the position adjusting member 70 to the optical disk surface. Even when the slide base 10 is displaced in a direction perpendicular to the main guide bearing holding member 20, the slide base 10 does not float up from the main guide bearing holding member 20 (without height fluctuation). The translation can be performed only in the Ta direction.
[0024]
Next, a description will be given of a Ta shift adjusting operation for adjusting the parallel movement of the slide base 10 with respect to the main guide bearing holding member 20 in the Ta direction. Also in the present embodiment, it is assumed that the optical disk device employs a tracking servo system based on a three-beam method. It is also assumed that the focus servo adjustment has been completed before the Ta shift adjustment is performed. That is, in the optical head device of the present embodiment, before the optical element group 30 is assembled, the main guide shaft 50 or the reference guide shaft for assembly (not shown) is inserted through the main guide bearing holding member 20, and The guide bearing holding member 20 is held on the slide base 10 by a leaf spring portion 10d and a position adjusting member 70 in which an adjusting screw 75 is screwed. In this state, an optical element positioning jig base (not shown) is used. ), The optical element group 30 is assembled, and then mounted on a mechanical chassis (not shown) to complete the focus servo adjustment.
[0025]
As described above, after the focus servo adjustment is completed, the optical disk 90 is mounted, the spindle motor 100 is driven to rotate the optical disk 90, and the signal recording surface of the optical disk 90 is irradiated with the beam light. The return light reflected from the signal recording surface is detected by the light receiving element, and the light is converted into an electric signal, and a Lissajous waveform obtained by synthesizing a sub-beam signal for tracking is observed. Then, the position of the slide base 10 in the Ta direction is adjusted by rotating the adjusting screw 75 using the adjusting screw driver 80 so that the aspect ratio of the Lissajous waveform falls within the specified range.
[0026]
As described above, the position adjusting member 70 is displaced only in the direction orthogonal to the optical disk surface by rotating the adjusting screw 75. As the position adjusting member 70 is displaced in a direction perpendicular to the optical disk surface, the tapered portion 70b of the position adjusting member 70 slides on the arc surface of the main guide bearing holding member 20, and thereby the position adjusting member 70 3 is displaced in the direction of arrow H in FIG. 3, the slide base 10 is displaced in the direction of arrow J in FIG. 3 with respect to the main guide bearing holding member 20, and the position adjusting member 70 is moved in the direction of arrow I in FIG. When displaced, the slide base 10 is displaced relative to the main guide bearing holding member 20 in the direction of arrow K in FIG. That is, due to the displacement of the position adjusting member 70 in the direction orthogonal to the optical disk surface, the slide base 10 does not rise from the main guide bearing holding member 20 (without height fluctuation), and the slide base 10 holds the main guide bearing. The slide base 10 is moved in parallel only in the Ta direction with respect to the member 20, whereby the Ta shift adjustment of the slide base 10 is achieved.
[0027]
As described above, when the position of the slide base 10 is adjusted so that the aspect ratio of the Lissajous waveform is within the specified range by adjusting the position of the slide base 10 in the Ta direction, the adjusting screw driver 80 is adjusted to the adjusting screw 75. , Thereby completing the Ta shift adjustment of the slide base 10.
[0028]
FIG. 4A shows a case where a Ta shift occurs by −Δt on the slide base 10, and FIG. 4B shows a case where a Ta shift occurs by + Δt on the slide base 10. The Ta shift of the slide base 10 is adjusted so as to correct these Ta shifts.
[0029]
In the above-described embodiment, the guide notch is provided on the slide base 10 and the protrusion is provided on the position adjusting member 70 so that the position adjusting member 70 can be moved in parallel only in a direction perpendicular to the optical disk surface. However, the relationship between the irregularities may be reversed.
[0030]
【The invention's effect】
As described above, according to the present invention, when adjusting the Ta shift of the slide base on which the optical element group is mounted, the Ta shift can be surely adjusted without causing a fluctuation in the height of the slide base. It is possible to provide an optical head device capable of coping with a higher density, larger capacity and smaller optical disk.
Further, the main guide bearing holding member is elastically supported by a leaf spring integrally provided on a metal plate slide base and a position adjustment member having a tapered portion by screwing an adjustment screw, and a slide base of the slide base is provided. By bringing the main surface and the main guide bearing holding member into close contact with each other, a mechanism for moving the slide base in parallel only in the Ta direction can be easily realized with a small number of parts. , Good workability.
[Brief description of the drawings]
FIG. 1A is an overhead perspective view of an optical head device according to an embodiment of the present invention, and FIG. 1B is a perspective view of the optical head device according to an embodiment of the present invention as viewed from above.
2A is a plan view of an optical head device according to an embodiment of the present invention, FIG. 2B is a cross-sectional view taken along line AA of FIG. 2A, and FIG. FIG. 3D is a cross-sectional view along the line B, and FIG. 4D is a cross-sectional view along the line CC in FIG.
FIG. 3 is an enlarged view of a main part of FIG. 2 (d).
FIGS. 4A and 4B are explanatory views showing a state of Ta displacement of a slide base in the optical head device according to one embodiment of the present invention.
FIG. 5A is a bird's-eye perspective view of a conventional optical head device, and FIG. 5B is a perspective view of the conventional optical head device as viewed from above.
6A is a bottom view of the conventional optical head device, FIG. 6B is a cross-sectional view taken along line AA in FIG. 6A, and FIG. 6C is a sectional view taken along line BB in FIG. It is sectional drawing.
[Explanation of symbols]
Reference Signs List 10 Slide base 10d Leaf spring portion 10e Guide notch portion 20 Main guide bearing holding member 30 Optical element group 40 Lens actuator 50 Main guide shaft 60 Sub guide shaft 70 Position adjusting member 70a Projecting portion 70b Tapered portion 70c Screw hole 75 Adjusting screw 80 Adjustment screw driver 90 Optical disk 100 Spindle motor

Claims (3)

A slide base on which an optical element group and a lens actuator of an objective lens in the optical element group are mounted; and a main guide bearing holding member which is inserted and guided by a main guide shaft and to which the slide base is attached so as to be adjustable in position. An optical head device in which the slide base and the main guide bearing holding member are integrally scanned along the radial direction of the optical disc,
The slide base is always in contact with the main guide bearing holding member, and the position of the slide base can be adjusted in a direction perpendicular to the optical disk surface. On the other hand, by attaching a position adjusting member that gives a displacement in a direction parallel to the optical disk surface and orthogonal to the optical head scanning direction,
By adjusting the position of the position adjusting member in a direction perpendicular to the optical disk surface, only the relative positional relationship between the slide base and the main guide bearing holding member in a direction parallel to the optical disk surface and orthogonal to the optical head scanning direction is obtained. The optical head device is configured to be adjustable. In claim 1,
The slide base is made of a metal plate, a leaf spring portion is integrally formed on the slide base, and the main guide bearing holding member is elastically sandwiched between the leaf spring portion and the position adjusting member. By the spring portion, the main guide bearing holding member and the main body of the slide base are always in close contact with each other,
An optical head device, wherein a tapered portion is formed at a position of the position adjusting member that abuts on the main guide bearing holding member. In claim 1 or 2,
The slide base and the position adjustment member are assembled by engaging a guide notch provided on one side thereof and extending in a direction orthogonal to the optical disk surface with a projection provided on the other side, and the position adjustment member is Displaceable only in the direction perpendicular to the optical disk surface with respect to the slide base,
An optical head device wherein the position adjusting member is displaced in a direction orthogonal to the optical disk surface by rotating an adjusting screw screwed to the position adjusting member.

Images