JPH0963063A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical pickup in which the positional fluctuation of the image side principal point is lessened at the time of the tangential skew adjustment of the pricipal point by making a plane perpendicular to an optical axis passing a holding part falcrum and passing the image side principal point of an objective lens and a plane passing the image side principal point of the objective lens and perpendicular to the optical axis coincide. SOLUTION: In this optical pickup 10, a movable part 20 holds an objective lens 21 converging the laser beam emitted from a laser beam source on the signal recording surface of an optical disk and a yoke 30 elastically holds the movable part 20 by wires 55 of elastic bodies. Moreover, a tangential skew adjusting mechanism makes the yoke 30 rotatable and adjustable around the yoke side falcrum 31. Consequently, the plane perpendicular to the optical axis passing the falcrum 31 and passing the image side principal point 22 of the objective lens 21 and the plane passing the falcrum 31 and perpendicular to the optical axis are made to almost coincide and the adjustment is facilitated and the accuracy of the adjustment is improved by lessening the positional fluctuation of the principal point 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup for reading and reproducing a recording signal of an optical disc, and more specifically, a tangential of an objective lens for converging laser light emitted from a laser light source onto a signal recording surface of the optical disc. The present invention relates to a tilt adjusting mechanism for an objective lens that adjusts the tilt in a direction.

[0002]

2. Description of the Related Art In an optical disk player using an optical disk as a recording medium, an optical pickup is used as means for reading and reproducing information signals recorded on the disk. The optical pickup converges a laser beam emitted from a laser light source as a beam spot on a signal recording surface of an optical disc into a pit row, which is a minute irregularity, as a beam spot through an objective lens, and is reflected from the pit row. An information signal is read and reproduced by detecting the state of the reflected beam with a photodetector.

When a laser beam is focused on the pit row of an optical disk as a beam spot via an objective lens, the optical axis of the objective lens is maintained exactly perpendicular to the signal recording surface of the optical disk. If not, aberration occurs in the beam spot focused on the pit row,
A noise component may be superimposed on an information signal to be read and reproduced, and the reproduction characteristics may be degraded, or the information signal may not be read and reproduced depending on the degree. Therefore, in an optical pickup used in an optical disc player or an optical recording / reproducing apparatus, the laser beam is applied to the signal recording surface of the optical disc so that the laser beam always enters the signal recording surface of the optical disc perpendicularly. There are various types of devices that are equipped with a mechanism for adjusting the inclination of the optical axis of the objective lens that focuses the light on.

An example of a conventional optical pickup will be described with reference to FIGS. 8 and 9. FIG. 8 is a front view showing a configuration of a conventional optical pickup, FIG. 9 is a view showing setting positions of an image side principal point of a conventional objective lens and a fulcrum of an adjustment mechanism, (a) is a front view, and (b) is a front view. ) Is a top view. An optical pickup 100 includes a movable portion 110, a yoke 120, a base 130,
The adjusting screw 140 and the wire 150 are included.

In the movable part 110, an objective lens 111 for condensing a laser beam on a signal recording surface of an optical disk and a magnetic coil (not shown) are fixed to a resin member. The movable part 110 is made up of four elastic body (for example, phosphor bronze) ultra-small diameter wires 150, two fixed on each side.
It is elastically held by the yoke 120. York 120 is L
The fixed portion 121 of the wire 150 that elastically holds the movable portion 110 in the vertical direction, and the tangential skew of the objective lens 111 (the tilt angle in the tangential direction of the disc) in the horizontal direction are formed. A screw hole 123 into which the adjusting screw 140 to be adjusted is screwed, and a V-shaped fulcrum 122 that is a fulcrum of the seesaw operation when adjusting the tangential skew are formed. York 12
0 is engaged with the coil of the movable portion 110 to form a magnetic circuit (not shown).

The base 130 is a base portion of the optical pickup 100, and has a screw hole 131 and the like into which an adjusting screw 140 for adjusting the tangential skew is screwed.
Next, the operation of adjusting the tangential skew will be described.
The image point side principal point 112 of the objective lens 111 and the disk 170
When adjusting the tangential skew with respect to the plane of, for example, the direction E, the V-shaped fulcrum 12 of the yoke 120 is used.
2 to the adjustment screw 140 on the left side of the screw hole 12 of the yoke 120.
At the same time as turning it in the direction of coming out of 3, adjust screw 14 on the right side
When 0 is turned in the direction of screwing into the screw hole 123 of the yoke 120, the yoke 120 tilts in the F direction with the V-shaped fulcrum 122 of the yoke 120 as a fulcrum, and the wire 15 is attached to the yoke 120.
The objective lens 111 of the movable part 110 held at 0 tilts in the E direction and the tangential skew is adjusted. still,
When adjusting in the direction opposite to the E direction, the left adjustment screw 140
The operation of the adjusting screw 140 on the right side may be reversed from that in the E direction.

[0007]

However, in the above optical pickup 100, when the tangential skew is adjusted, the center shift between the center of the optical disc and the center of the objective lens 111 (arrow e) and the offset in the focus direction (arrow). This caused problems such as f). The center shift causes a problem of traverse level variation because the three spot angles used for detecting a track and a tracking error are apparently different between the inner circumference and the outer circumference of the optical disc. Further, the offset in the focus direction is the same as that of the objective lens 111 when the offset occurs in the direction in which the objective lens and the optical disc approach each other.
And the problem of optical disc interference occurs.

Therefore, the present invention solves the above-mentioned problems, and an object of the present invention is to provide an optical pickup in which the position variation of the image-side principal point is small during the tangential skew adjustment of the image-side principal point of the objective lens. To do.

[0009]

The present invention achieves the above-mentioned object, and in an optical pickup for reading and reproducing a recording signal of an optical disc, a laser beam emitted from a laser light source is converged on a signal recording surface of the optical disc. And a tangential skew adjusting mechanism capable of rotating the holding part around a fulcrum, and the lens passing through the fulcrum. The plane perpendicular to the optical axis passing through the image-side principal point and the plane perpendicular to the optical axis passing through the principal point are substantially coincident with each other.

Further, in an optical pickup for reading and reproducing a recording signal of an optical disc, a movable portion holding an objective lens for converging a laser beam emitted from a laser light source onto a signal recording surface of the optical disc, and the movable portion are elastically held. And a tangential skew adjustment mechanism capable of rotating the holding part around a fulcrum as a center, and the optical axis is a plane perpendicular to the radial direction including the optical axis passing through the image-side principal point of the lens. It is characterized in that the axis and a straight line passing through a point obtained by projecting the fulcrum on the plane and parallel to the optical axis are substantially coincident with each other.

Further, on a plane which includes the optical axis passing through the image-side principal point of the lens and is perpendicular to the radial direction, the optical axis and a straight line passing through the point where the fulcrum is projected onto the plane and parallel to the optical axis are The feature is that they substantially match. Also, one of the fulcrums of the tangential skew adjusting mechanism is a V-shaped fulcrum, and the shape of the fulcrum on the mating side that engages with the fulcrum is a square groove.

Further, one of the fulcrums of the tangential skew adjusting mechanism is a V-shaped fulcrum, and the fulcrum of the mating side engaging with the fulcrum is a V-shaped groove.
Further, one of the fulcrums of the tangential skew adjusting mechanism is a V-shaped fulcrum, and the shape of the fulcrum of the other side engaging with the fulcrum is a semicircular groove.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. 1 is a front view showing the configuration of an optical pickup, FIG. 2 is a view showing the setting positions of an image-side principal point of an objective lens and a fulcrum of an adjusting mechanism, (a) is a front view, and (b) is a top view. It is a figure.

An optical pickup 10 is composed of a movable portion 20, a yoke 30, a base 40, an adjusting screw 50, a wire 55 and the like. The movable part 20 has an objective lens 21 for condensing a laser beam on a signal recording surface of an optical disc and a magnetic coil (not shown) fixed to a resin member.
The movable portion 20 is elastically held by the yoke 30 by four extremely small wires 55 of elastic body (for example, phosphor bronze) fixed to the movable portion 20 such that two movable portions are provided on each side.

The yoke 30 is provided with a plurality of columnar portions which are vertically provided with respect to the bottom portion 34, and two V-shaped fulcrums 31, which are fulcrums for seesaw operation when adjusting the tangential skew, are movable. The fixing portion 32 of the wire 55 that elastically holds the portion 20 is formed. Also, the bottom 33
A screw hole 34 into which an adjusting screw 50 for adjusting the tangential skew of the objective lens 21 (the tilt angle in the tangential direction of the disk) is screwed is formed in the. The yoke 30 engages with the coil of the movable portion 20 to form a magnetic circuit (not shown).

The base 40 is a base portion of the optical pickup 10 and is a fulcrum 4 on the base side which engages with a fulcrum 31 of the yoke 30.
1 is formed. Further, a screw hole 42 or the like into which an adjusting screw 50 for adjusting the tangential skew of the objective lens 21 is screwed is formed in a state of being assembled with the yoke 30. Next, the setting position of the fulcrum of the tangential skew adjusting mechanism will be described.

The setting position of the fulcrum 31 of the tangential skew adjusting mechanism is the distance between the optical disk (not shown) and the image-side principal point 22 of the objective lens 21, and the distance between the optical disk and the fulcrum 31 of the tangential skew adjusting mechanism. The distances between the image-side principal point 22 of the objective lens 21 and the fulcrum 31 of the tangential skew adjusting mechanism are set to coincide with each other on an extension line connecting the image-side principal point 22 of the objective lens 21 and the fulcrum 31 of the tangential skew adjusting mechanism. It is set in place.

Next, the adjustment of the tangential skew will be described. When the tangential skew of the objective lens 21 with respect to the image-side principal point 22 and the disc is rotated, for example, in the A direction, the adjustment screw 50 on the left side of the V-shaped fulcrum 31 of the yoke 30 is attached to the screw hole of the yoke 30. 32
When the adjusting screw 50 on the right side is turned in the direction of being screwed into the screw hole 34 of the yoke 30 at the same time as turning it in the direction away from the yoke 30, the yoke 30 moves to the B-shaped fulcrum 31 of the yoke 30 as a fulcrum.
The objective lens 21 of the movable part 20 which is tilted in the direction and held by the wire 55 on the yoke 30 is tilted in the direction A, and the tangential skew is adjusted. When moving and adjusting in the direction opposite to the A direction, the operations of the left adjusting screw 50 and the right adjusting screw 50 may be reversed from those in the A direction.

As described above, according to the present embodiment,
By matching the distance between the optical disk and the image-side principal point 22 of the objective lens 21 and the distance between the optical disk and the fulcrum 31 of the tangential skew adjusting mechanism, the occurrence of center deviation and focus direction offset is reduced, and the tangential is reduced. When performing skew adjustment, only angle adjustment can be performed independently. Therefore, the tangential skew adjustment becomes easy, and the adjustment accuracy also improves.

Next, a second embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. 3 is a front view showing the configuration of the optical pickup, FIG. 4 is a view showing the setting positions of the image-side principal point of the objective lens and the fulcrum of the adjustment mechanism, (a) is a front view, and (b) is a view.
Is a top view. In the following embodiments, the position of the fulcrum of the tangential skew adjusting mechanism of the first embodiment is changed, and the other points are substantially the same as the configuration of FIG. 1, so the same configuration as that of FIG. Are denoted by the same reference numerals and description thereof will be omitted.

The setting position of the fulcrum of the tangential skew adjusting mechanism will be described. The fulcrum 60 of the tangential skew adjusting mechanism is set at a position where the distance between the optical disc and the image-side principal point 22 of the objective lens 21 matches the distance between the optical disc and the fulcrum 60 of the tangential skew adjusting mechanism. The distance between the image-side principal point 22 of 21 and the fulcrum 60 of the tangential skew adjustment mechanism is
It is set at a predetermined position on an extended vertical surface that extends downward (downward in the drawing) through the image-side principal point 22 of the objective lens 21.

As described above, according to this embodiment,
On a plane that passes through the optical axis of the objective lens 21 and is perpendicular to the radial direction of the optical disc, the image-side principal point 22 of the objective lens 21
By aligning the fulcrum 60 of the tangential skew adjustment mechanism with the tangential direction, the offset in the focus direction can be suppressed to the minimum. Therefore, the tangential skew adjustment becomes easy, and the adjustment accuracy also improves.

Next, a third embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. 5 is a front view showing the configuration of the optical pickup, FIG. 6 is a view showing the setting positions of the image-side principal point of the objective lens and the fulcrum of the adjusting mechanism, (a) is a front view, and (b) is a view.
Is a top view. In the third embodiment, the position of the fulcrum of the tangential skew adjusting mechanism of the first embodiment is changed, and the other points are substantially the same as the configuration of FIG. 1, so the same configuration as that of FIG. Are denoted by the same reference numerals and description thereof will be omitted.

Next, the setting position of the fulcrum of the tangential skew adjusting mechanism will be described. The setting position of the fulcrum 70 of the tangential skew adjusting mechanism is such that the distance between the optical disc and the image-side principal point 22 of the objective lens 21 and the distance between the optical disc and the fulcrum 70 of the tangential skew adjusting mechanism are the same. 21 of the image side principal points 21
The distance between and the fulcrum 70 of the tangential skew adjusting mechanism is set to a position as close as possible to the image-side principal point 22 of the objective lens 21.

As described above, according to this embodiment, the distance between the optical disk and the image side principal point 22 of the objective lens 21 and the fulcrum 7 of the optical disk and the tangential skew adjusting mechanism.
In a plane which is equal in distance to 0 and which passes through the optical axis of the objective lens 21 and is perpendicular to the radial direction of the optical disc,
By making the image-side principal point 22 of the objective lens 21 and the fulcrum 70 of the tangential skew adjusting mechanism substantially coincide with the tangential direction, the center shift and the focus direction offset can be suppressed to a minimum.
Therefore, tangential skew adjustment becomes easier,
Adjustment accuracy is also improved.

Next, the fulcrum portion of the adjusting mechanism of this embodiment will be described with reference to FIG. 7A and 7B are views showing the configuration of the fulcrum portion of the adjusting mechanism of the present embodiment, where FIG. 7A is a sectional view showing the fulcrum portion of the first configuration, and FIG. 7B is a sectional view showing the fulcrum portion of the second configuration. , (C) are sectional views showing the fulcrum portion of the third configuration.
First, the fulcrum portion of the first configuration will be described.

Reference numeral 30 is a yoke, and the movable portion 20 is a wire 55.
Is held elastically (not shown) by the objective lens 2
A fulcrum portion (V shape) 35 of the tangential skew adjusting mechanism 1 and a screw hole (not shown) into which an adjusting screw (not shown) is screwed are formed. Reference numeral 40 denotes a base, and a base-side fulcrum portion (square groove) 45 that engages with the fulcrum portion 35 of the yoke 30 is formed. In addition, the objective lens 21 formed on the yoke 30 is assembled with the yoke 30.
A screw hole (not shown) into which an adjusting screw (not shown) for adjusting the tangential skew is screwed is formed.

The fulcrum portion of the first construction is a fulcrum portion on the side of the yoke 30 by engaging a fulcrum portion (V shape) 35 on the side of the yoke 40 and a fulcrum portion (square groove) 45 on the side of the base 40. The position of the 35 parts can be restricted so as to be movable only within a predetermined range. Next, the fulcrum portion of the second configuration will be described. In the following examples, the shape of the fulcrum portion (reception side) on the base side of the fulcrum portion of the first configuration is changed, and the other points are substantially the same, so the same reference numerals are given to the same configurations. The description is omitted.

Reference numeral 40 denotes a base, which is a fulcrum portion 35 of the yoke 30.
A fulcrum portion (V groove) 46 on the base side that engages with is formed. Further, in the state where it is assembled with the yoke 30, the yoke 3
A screw hole (not shown) into which an adjusting screw (not shown) for adjusting the tangential skew of the objective lens 21 configured to be 0 is screwed is formed. The fulcrum portion of the second structure is formed by engaging the fulcrum portion (V shape) 35 on the yoke 30 side and the fulcrum portion (V groove) 46 on the base 40 side.
The fulcrum portion 35 on the yoke 30 side can be positionally regulated at a predetermined position.

Next, the fulcrum portion of the third structure will be described. Reference numeral 40 denotes a base, and a base-side fulcrum portion (semicircular groove) 47 that engages with the fulcrum portion 35 of the yoke 30 is formed.
Further, a screw hole (not shown) into which an adjusting screw (not shown) for adjusting the tangential skew of the objective lens 21 formed in the yoke 30 is screwed in the assembled state with the yoke 30 is formed.

The fulcrum portion of the third structure engages with the fulcrum portion (V shape) 35 on the yoke 30 side and the fulcrum portion (semi-circular groove) 47 on the base 40 side so that the fulcrum portion on the yoke 30 side is engaged. It is possible to regulate the position of the fulcrum portion 35 on the yoke 30 side while also having the fulcrum portion 35 with a predetermined degree of freedom. As described above, the first, the second and the third of the present embodiment
According to the fulcrum part of the configuration of FIG.
It is possible to prevent the center deviation of 2 from increasing. Therefore,
The tangential skew adjustment becomes easy, and the adjustment accuracy also improves. As the fulcrum portion of the adjusting mechanism shown in FIG. 7, a fulcrum having a structure suitable for the fulcrum portion of the tangential skew adjusting mechanism of the first to third embodiments is selected and used.

[0032]

As described above, according to the present invention, when the tangential skew adjustment of the objective lens is performed, the center shift between the center of the optical disc and the center of the objective lens and the offset amount in the focus direction are unlikely to occur. .

[Brief description of drawings]

FIG. 1 is a front view showing the configuration of an optical pickup according to a first embodiment of the present invention.

2A and 2B are diagrams showing the setting positions of the image-side principal point of the objective lens and the fulcrum of the adjusting mechanism of the first embodiment of the present invention, FIG. 2A being a front view and FIG. 2B being a top view.

FIG. 3 is a front view showing a configuration of an optical pickup according to a second embodiment of the present invention.

4A and 4B are views showing the setting positions of an image-side principal point of an objective lens and a fulcrum of an adjusting mechanism of a second embodiment of the present invention, FIG. 4A being a front view and FIG. 4B being a top view.

FIG. 5 is a front view showing a configuration of an optical pickup according to a third embodiment of the present invention.

6A and 6B are diagrams showing setting positions of an image side principal point of an objective lens and a fulcrum of an adjusting mechanism of a third embodiment of the present invention, FIG. 6A being a front view and FIG. 6B being a top view.

FIG. 7 is a view showing a configuration of a fulcrum portion of the adjusting mechanism of the embodiment of the present invention, (a) is a cross-sectional view showing the fulcrum portion of the first configuration,
(B) is sectional drawing which shows the fulcrum part of 2nd structure, (c) is sectional drawing which shows the fulcrum part of 3rd structure.

FIG. 8 is a front view showing a configuration of a conventional optical pickup.

9A and 9B are diagrams showing the setting positions of the image-side principal point of the conventional objective lens and the fulcrum of the adjustment mechanism, in which FIG. 9A is a front view and FIG. 9B is a top view.

[Explanation of symbols]

 10 ... Optical pickup 20 ... Movable part 21 ... Objective lens 22 ... Image side principal point 30 ... Yoke 31, 35, ... Yoke side fulcrum 40 ... Base 41, 45, 46, 47 ... Base side fulcrum 50 ... Adjustment screw 55 ... Wire

Claims (6)

[Claims] 1. An optical pickup for reading and reproducing a recording signal of an optical disc, wherein a movable portion holding an objective lens for converging laser light emitted from a laser light source onto a signal recording surface of the optical disc, and elastically holding the movable portion. And a plane perpendicular to the optical axis passing through the fulcrum and passing through the image-side principal point of the lens, and a tangential skew adjusting mechanism that is capable of rotating the holding section around a fulcrum. An optical pickup characterized by being substantially coincident with a plane passing through a point and being perpendicular to the optical axis. 2. In an optical pickup for reading and reproducing a recording signal of an optical disc, a movable part holding an objective lens for converging laser light emitted from a laser light source onto a signal recording surface of the optical disc, and elastically holding the movable part. And a tangential skew adjustment mechanism capable of rotating the holding portion around a fulcrum, and the optical axis is a plane perpendicular to the radial direction including the optical axis passing through the image-side principal point of the lens. An optical pickup characterized in that an axis and a straight line passing through a point obtained by projecting the fulcrum on the plane and parallel to the optical axis are substantially coincident with each other. 3. On a plane perpendicular to the radial direction including the optical axis passing through the image-side principal point of the lens, the optical axis and a straight line passing through a point projecting the fulcrum on the plane and parallel to the optical axis The optical pickup according to claim 1, wherein the optical pickups match each other. 4. The light according to claim 1, wherein one of the fulcrums of the tangential skew adjusting mechanism is a V-shaped fulcrum, and the fulcrum of the other side engaging with the fulcrum is a square groove. pick up. 5. The light according to claim 1, wherein one of the fulcrums of the tangential skew adjustment mechanism is a V-shaped fulcrum, and the shape of the fulcrum on the other side engaging with the fulcrum is a V groove. pick up. 6. The fulcrum of the tangential skew adjusting mechanism has one of fulcrums as a V-shaped fulcrum, and the fulcrum of the other side engaging with the fulcrum is a semicircular groove. Optical pickup.