JPS59223943A - Optical disc device - Google Patents

Abstract

PURPOSE:To prevent the generation of coma aberration in case of correction of the optical axis of an optical block and prevent the deviation of a read point by oscillating the optical block in accordance with the inclination of a disc and oscillating a reflective mirror at a half angle of this oscillatory angle. CONSTITUTION:An optical block 13 is oscillated in accordance with an inclination DELTAtheta of a disc 12 to correct an optical axis OA vertically to the disc 12. A connecting member 20 is oscillated with a fulcrum 21 as the center in the direction of an arrow (b) by a motor 28 to perform this correction. In this oscillation, a fulcrum 35 of a connecting member 33 is oscillated with a fulcrum 14 as the center in the direction of an arrow (g) by the oscillatory action of a bending end 20d of the connecting member 20. The connecting member 33 is oscillated at a half of the oscillatory angle DELTAtheta of the optical block 13, and a reflective mirror 34 is oscillated at an angle DELTAtheta/2 to make the luminous flux from a fixed part 37 coincident with the optical axis OA. Consequently, coma aberration is not generated. A deviation DELTAx of a read point P which is generated in this case is corrected by the oscillatory action of the other end 20b of the connecting member 20 to the fulcrum 21.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical disc device, and more particularly to control of a reading optical system.

Background Art and Problems In the reading optical system of an optical disc device, focus control is performed so that the light beam emitted from a laser light source is focused on the disc by an objective lens, and the optical axis is aligned with the disc. Tracking control is performed to match the information pit rows forming the track. Then, information consisting of a pit array is read by reflected light at a spot with a finite spread determined by the wavelength of the laser light source and the numerical aperture of the objective lens. Therefore, during reading, it is necessary to always make the optical axis of the light beam from the laser light source perpendicular to the disk. However, if the disk is tilted due to warping or the like, the light beam from the laser light source will not be incident on the disk perpendicularly, causing coma aberration at the reading point of the disk and degrading the reading respot.

Then, the RF level, tracking error, focus error, and especially crosstalk deteriorate, and in the worst case, it becomes impossible to obtain focus. Incidentally, the inclination due to warpage of the disk is particularly large in the radial direction of the circumferential direction and the radial direction of the disk, and it is necessary to correct the skew of the optical axis for this inclination in the radial direction.

As such skew correction, there has conventionally been a method of tilting the optical system according to the inclination of the disk so that the optical axis is always perpendicular to the disk.

The optical system in this conventional method includes all various optical elements such as a laser light source and an objective lens, and is configured to tilt the entire optical system. However, an optical system that includes all of the various optical elements is large and heavy as a whole, so the dynamic characteristics of the optical system's feeding mechanism and swinging mechanism are not good, and the wiring of harnesses for connecting various signals is difficult. There were problems such as being troublesome.

Therefore, the inventor of the present application constructed an optical system by separating it into a head part mainly containing an objective lens and a fixed part mainly containing a laser light source. When performing skew correction by tilting the head section according to the inclination of the disk, we experimented with a method in which the reflecting mirror was tilted together with the head section. However, with this method, due to the relationship between the incident angle and the reflection angle of the reflecting mirror, the light beam is tilted twice as much as the head, and the light beam deviates from the optical axis of the objective lens. A new problem has arisen in that coma aberration at the reading point of the disc is increased.

OBJECTS OF THE INVENTION The present invention aims to provide an optical disc device that can solve the above-mentioned problems.

Summary of the Invention The present invention includes an optical block that is swingably supported with respect to a feed block around a fulcrum placed on the optical axis, a reflecting mirror that is rotatable around the fulcrum, and a reflection mirror that is rotatable around the fulcrum. A light source is provided on a fixed part and is configured to be reflected by the reflecting mirror and irradiated onto the optical block, and the optical block is swung around the fulcrum in accordance with the inclination of the disk, and the optical block is also swung. An optical disc device comprising a swinging mechanism for synchronously swinging the reflection mirror 2- at an angle of 10 ψ of the moving angle, the optical disc device is provided with a swinging mechanism that swings the reflection mirror 2- in synchronization at an angle of ten ψ of the swing angle. , the light beam reflected by the reflecting mirror can always be aligned with the optical axis of the objective lens.

Since the head portion and the fixed portion can be configured separately, it is possible to take advantage of advantages such as improving the dynamic characteristics of the feeding mechanism and the swinging mechanism by making the head portion thinner.

Embodiment Hereinafter, an embodiment of an optical disc device to which the present invention is applied will be described based on the drawings.

First, in FIGS. 1 to 4, the head section (10) is composed of an objective lens (11) and various other optical elements, and the head section (10) is composed of an objective lens (11) and various other optical elements. The head part (101 has a two-axis mechanism that can perform tracking control and focus control by itself.The head part (101 is mounted on an optical block (131). The α wrinkle is located at the first fulcrum (1
4) Send block t151 through! It is pivoted so that it can swing freely. Note that this first fulcrum αa is the fulcrum in the present invention. The feed block (11) is guided by a pair of guides (16aX16b) provided along the radial direction of the disk (121), which is the direction of arrow a in FIG. 2, and is movable in the direction of arrow a. Therefore, the optical block (1) can be freely swung relative to the old Ma feed block Kasumi,
In addition, it is configured to be movable in the direction of arrow a together with the feed block Kasumi. And the movement of the feed block ttS+ is as follows:
This is done by a feed screw (II) provided below the feed block (151 along the direction of arrow a) and rotated around its axis by a first motor αη.

Therefore, the feed block (I51) and the feed screw (1st stage) are connected by the first connecting member (A).
The connecting member (2CI is swingably supported on the feed block 4 via the second fulcrum), and one end (20a
) provided in the retaining part (two are the first parts facing the optical block).
A third fulcrum (23) provided at an eccentric position with respect to the fulcrum (la) is engaged with the third fulcrum (23).The other end (20b) of the first connecting member (to) is screwed into the barrel of the feed screw α. It is engaged with a nut consisting of a half nut via a fourth fulcrum (c).The fourth fulcrum (to) is connected to a pair of vertically extending grooves (24a) provided in the nutro force. , are engaged in a slidable state in the vertical direction. Also, the nut I24) connects its upper end to the connecting member of the mortuary 1 (
20) and the other end (20b) of 1. It is pressed by a spring (26) and screwed into a feed screw (181).

Next, a worm gear (2″0) is formed on the protruding end (20c) of the first connecting member (2fl), and this worm gear (27) is connected to the second
The worm (2!1) of the motor (28) is engaged with the worm gear CD of the potentiometer (3 (ll) fixed to the feed block (15). .

On the other hand, a first fulcrum (14) of the optical block (14) is coaxial and extends inward, and a second connecting member (331) is rotatably supported around the first fulcrum (a). This second connecting member (3) has a reflecting mirror t34I in the center, and a fifth fulcrum (3: force) is provided at one end (53a) at an eccentric position with respect to the center of rotation. This fifth fulcrum C (51) is engaged with a retaining portion (row) provided at the bent end (20d) of the first connecting member (20j).

Note that the first and second connecting members (20+ (33) and their related parts constitute a swinging mechanism as referred to in the present invention.

Next, a fixed portion C37 is provided below the disk (12) at a position spaced apart from the feed block (151 by a predetermined distance in the lateral direction). This fixed part G7) is a laser light source (4
It has various optical elements including . Then, the light beam emitted from the laser light source (34J) is reflected by the second connecting member (bleached reflective mirror (34J),
The light is configured to be irradiated onto the head portion (10) of the optical block (13).

In the optical disc device of the present invention configured as described above, first, the first motor (1η) drives the feed screw (1η).
When 8) is rotated, the nut t24) screwed onto the feed screw (18) is moved. Since the first connecting member (201 is not swung unless the second motor (28) is rotated, the other end (20b)
When the fourth fulcrum (25+) is pressed by Nando (Incorporated), the first connecting member (20) and the feed block (t51) are moved as one. In case 1, when the first connecting member (201) is placed in a neutral state, the optical block (1) is also placed in a neutral state, and its optical axis OA is made perpendicular to the disk (121).

Note that the neutral state of the optical block (1) is detected by the potentiometer volume (3('ll).

Here, if the disk (12) is tilted by Δθ as shown by the virtual helix in FIG. 2, the optical block (1
The optical axis OA is corrected to be perpendicular to the disk (121) by swinging the optical axis.That is, when the disk (121) is tilted, the second motor is rotated and the optical axis OA is corrected perpendicularly to the disk (121).
G is swung in the direction indicated by the arrow around the second fulcrum (21). At this time, the first connecting member (
One end (20a) of □□□ is used for rocking motion;
a) The sixth fulcrum (2) engaged with the retaining part (2)
The optical block +131 is swung in the direction of arrow C around the first fulcrum (14J). Therefore, the optical axis OA of the optical block +131 is
It is tilted and corrected perpendicular to the disk Oz.

Note that the inclination of the optical block (131) is detected by the potentiometer volume CHI, and the potentiometer volume 01 also serves as a stopper when the optical block (13) is oscillated.

Therefore, when the first connecting member (2) is swung, the bent end (20) of the first connecting member (-) relative to the second fulcrum (2+)
d) for the swinging action, and the engaging part (3
The fifth fulcrum C351 of the second connecting member (G) engaged with 6) is swung in the direction of arrow g about the first fulcrum (14). That is, the second connecting member (to) is swung separately from the optical block (131).As will be described in detail later, the second connecting member (g) is swung at the angle of the optical block (13). The fixed part (37
) is tilted by Δθ to coincide with the optical axis OA of the optical block (1 to 1).

By the way, in this state, the reading point on the disc reflective surface (12a) becomes P', which is shifted by ΔX from the original reading point P. However, the deviation ΔX of the lever is corrected by the swinging action of the other end (20b) of the first connecting member opposite to the second fulcrum C.

That is, when the first connecting member end is swung, the second fulcrum C
The first connecting member (24) is for swinging in the direction of arrow d of the other end (20b) of υ, and the other end (24) is
The fourth fulcrum (20b) of 20b) (24) is screwed to the feed screw (18) and cannot be moved laterally, so the fourth fulcrum (24) is pressed against the second fulcrum υ. The swinging of the fulcrum I251 is converted into a swinging of the second fulcrum Q1) in the direction of the arrow e relative to the fourth fulcrum C, as shown by the imaginary lines in FIG. Since it is slidable in the vertical direction with respect to the fourth fulcrum (251 is an oak) (24), the second fulcrum (21) is moved in the direction of the arrow f, which is the lateral direction. Therefore, the feed block (
151 is an optical block (reading point P when 131 is tilted)
The optical axis OA of the optical block t13 is corrected to the original reading point P by being moved (returned) in the direction opposite to the deviation ΔX.

Next, with reference to FIGS. 5 and 6, the conditions under which the emitted light beam at the reading point P coincides with the optical axis OA will be explained.

First, in Fig. 5, the first fulcrum (1a), the second fulcrum (2a)
The optical block (1 optical axis OA
The swing angle of the first connecting member (2o) for tilting by Δθ is assumed to be Δθ'. Assuming that Δθ is minute, and assuming that the deviation ΔX of the reading point P is equal to the amount of movement of the fourth fulcrum (251), then OP×Δθ=O'R×Δθ' Since the amount of movement of the sixth fulcrum system is equal, OQ×Δθ=O′Q×Δθ) In order for the above two equations to hold true with arbitrary Δθ and Δθ′, OP O'R OQ O'Q is established. In other words, the reading point P for the first fulcrum side and the third
The reading point P The displacement ΔX of the fourth fulcrum (25) becomes equal to the amount of movement of the fourth fulcrum (25).As shown in FIG. The feed block t+51 is moved by converting it into a movement of the fulcrum Cυ.
"The optical block (131) is also moved by ΔX to correct the deviation of the reading point P.

Next, in order to tilt the light beam reflected by the reflection mirror 04) by Δθ, it is sufficient to tilt the anti-Δθ reflection mirror (b) by -2 from the relationship between the incident angle and the reflection angle. That is, in Fig. 5, since the amount of movement of the third fulcrum (23) is equal, QQXΔθ=:O/ QXΔθ' Also, since the amount of movement of the three fifth fulcrums L is equal, Δθ OS X: "= O' S XΔθ' From the above two equations, it becomes 0'Q 2XO'S OQ O8.In other words, the ratio of the distance between the second fulcrum side and the first fulcrum Cl4) to the third fulcrum f23) is
Second fulcrum C for 39! If it is equal to the ratio of twice the distance of υ and the distance of the first fulcrum (I4), the swing angle of the optical block (13) Δθ is 30, and the swing angle of the reflection mirror 2-(34) is is made -I. Therefore, the light beam reflected by the reflection mirror .nu. is tilted by .DELTA..theta. in the same manner as the optical block (1 to 1), and is aligned with the optical axis OA.

That is, according to the present invention, when the optical block 0S is oscillated by the oscillation of the first connecting member (2Ql), the reading point P
The deviation is due to the first connecting member (2υ is the feed block (151
By moving , automatic correction is always performed mechanically. Therefore, as shown in FIG.
is oscillated around the telephone number reading point P as the approximate center,
It is possible to prevent the reading point P from shifting when the optical axis OA is tilted according to the inclination of the disk (1) to be perpendicular to the disk a2. , the tracking control and focus control of the optical system OI itself are within the range that is easily possible.The swing of the optical block (13) and the accompanying correction of the deviation of the reading point P are performed by the first connecting member. Since (2) is performed simultaneously, skew correction can be performed extremely reliably.

Then, when skew correction is performed as described above, the first
The connecting member (to) oscillates the second connecting member provided with the reflecting mirror (34) in synchronization with an angle tenth of the oscillating angle of the optical block 03. Therefore, when the optical block u4 is swung according to the tilt of the disk Q, the light beam reflected by the reflecting mirror (b) is always aligned with the optical axis OA of the objective lens (11), so that the light beam is The occurrence of coma aberration due to deviation from the optical axis OA of the objective lens (1υ) is completely prevented.

Further, according to the present invention, since the head part 00) and the fixing part Gη can be configured separately, the head part 00) and the fixing part Gη can be configured separately.
) can improve the dynamic characteristics of the feeding mechanism and swinging mechanism. Furthermore, it becomes extremely easy to route harnesses for connecting various signals. In addition, the laser light source (4) has various advantages by separating the head part (10) and the fixed part 67, such as the fact that the adjustment part is extremely easy because the adjustment part is located in the fixed part (3 parts). be able to.

Next, detection of the inclination of the disk (121) will be explained based on FIGS. 7 and 8. First, as shown in FIG. The emitted light flux from the light source is transmitted through a prism beam splitter (43) and a collimator lens (44).
) and is irradiated onto a reflecting mirror (goods). Furthermore (4
2 is the photodetector in the adjustment section. and reflective mirror l34
) is reflected by the beam splitter (4e
1■ Wave plate (via 4η and objective lens 1υ sequentially,
A fine spot is formed on the disc reflective surface (12a). The reflected light beam reflected and diffracted by the disk reflective surface (12a) is transmitted to the objective lens (11), a 7-wave plate (4η
, a beam splitter (41) and a convex lens (4FtI), and enter the light receiving surface of a photodetector (41).
If it is tilted by θ, the reflected light flux from one side of the disk to the beam splitter (4119) is 2. The reflected light beam projected onto the light receiving surface of the photodetector (4ω) is laterally displaced in the projected radial direction a' as shown in FIG. 8. The displacement distance ΔL is 2-s ΔL = −, 2-Δθ, f.

2 B: This is the optical path length between the convex lens (body) and the light receiving surface of the photodetector (41) and 7.

The light-receiving surface of the photodetector (49) is formed by two light-receiving areas A and B aligned in the projected radial direction a' as shown in the figure. In order to simplify the explanation, the number and arrangement of the light-receiving areas A1B limit the detection of the inclination of the disks α to only the radial direction a, and no consideration is given to tracking control and focus control. do not have. And the output difference Sa between these light receiving areas A and B
By obtaining = SA −SB, the output difference S
By rotating the second motor in the forward and reverse directions according to the angle a, the optical block (131) can be swung so that its optical axis OA can always be tilted perpendicularly to the disk (121).

Note that the first connecting member (2I) and the second connecting member (3), which constitute the swinging member in the present invention, are not limited to the shapes shown in the embodiments, and can be modified in various ways. .

Application Example Although one embodiment of the present invention has been described above, the optical disc device of the present invention can be applied to video discs, audio discs, and various other information processing discs.

Effects of the Invention The present invention allows an optical block to be swingably supported with respect to a feed block around a fulcrum placed on the optical axis, and is provided with a reflecting mirror that is rotatable around the fulcrum. A light source is provided on a fixed part and is configured to be reflected by the reflecting mirror and irradiated onto the optical block, and the optical block is swung around the fulcrum in accordance with the inclination of the disk, and the optical block is also swung. Since this is an optical disc device equipped with a swinging mechanism that synchronizes the reflecting mirrors at ten angles of movement, the optical block is tilted according to the inclination of the disc to align its optical axis with respect to the disc. When correcting the beam so that it is always vertical, the beam reflected by the reflecting mirror can always be aligned with the optical axis of the objective lens. Therefore, the occurrence of coma aberration due to deviation of the light beam from the optical axis of the objective lens is completely prevented. Moreover, in this case, as shown in the embodiment, since the optical block can always be oscillated with the reading point as the approximate center, it is possible to prevent the reading point from shifting as much as possible, and the light beam is always directed to the original reading point. Can be irradiated accurately.

In addition, since skew correction is now possible in an optical system in which the head portion and the fixed portion are separated, the dynamic characteristics of the feeding mechanism and the swinging mechanism are improved by making the head portion lighter and thinner. Further, it is possible to take full advantage of various advantages resulting from separating the head portion and the fixed portion, such as making it extremely easy to route harnesses for connecting various signals.

[Brief explanation of the drawing]

The drawings show an embodiment of an optical disc device to which the present invention is applied, in which Fig. 1 is an exploded perspective view of the main parts, and Fig. 2 is a front view showing a state in which the optical block is swung. , Fig. 6 is a front view showing the state in which the feed block has been moved, Fig. 4 is a sectional view taken along the tv-tv line in Fig. 2, and Figs. 5 and 6 are corrected for the deviation of the reading point. 7 and 8 are cross-sectional views along the optical axis of the optical system and illustrative diagrams illustrating the method for detecting the inclination of the disk. FIG. 3 is a plan view of a light-receiving surface of a photodetector. In addition, in the symbols used in the drawings, 00) Head section old) -... Objective lens (121... Disk (131) Optical block (1 piece) First fulcrum (old) Feed block 07... 1st motor α barrel ・ ・ Feed screw ■ ・ ・ 1st connecting member (21) 2nd fulcrum ・ ・ 3rd fulcrum (24) ・ Nut (251・ 4th fulcrum side - 2nd motor (3) Second connecting member (34)...Reflecting mirror (351-fifth fulcrum 07)...Fixed part (4)... Laser light source. Agent Masaru Ueya l Yoshio Tsuneko l Toshiki Sugiura Figure 1-233- Figure 4 2

Claims (1)

[Claims] The optical block is swingably supported with respect to the feed block around a fulcrum placed on the optical axis, a reflecting mirror is provided that is rotatable around the fulcrum, and the light source of the optical block is provided on a fixed part. The optical block is configured to be reflected by the reflecting mirror and irradiated onto the optical block, and the optical block is swung around the fulcrum in accordance with the inclination of the disk, and at an angle of ten times the oscillating angle of the optical block. An optical disc device comprising a swinging mechanism that swings the reflecting mirror in synchronization.