JPS5853031A - Reproducer for optical information recording disc - Google Patents

Abstract

PURPOSE:To attain accurate tracking, by incorporatedly forming a mirror with a bobbin having two sets of coils, inserting the bobbin to a magnetic path so that the said coil can correspond to two sets of permanent magnets orthogonal with different height, and adjusting the current to the coils. CONSTITUTION:A mirror 1 is arranged in an optical path of a laser light source (not shown) and an optical pickup and fixed to one end of a coil bobbin 14. The coil bobbin is wound with two sets of coils 16 and 17 with different height, and the coils are opposed to pole pieces 4',5' and 6',7' of two sets of orthogonal permanent magnets with different height. A cylindrical yoke 10 is provided in the coil bobbin 14 and pole pieces 13 and 12 are provided opposing to the coils 16 and 17 for the upper and lower ends. The coil bobbin 14 is inserted in a magnetic path and supported freely rockingly with a one point pivot 9. The direction and amplitude of the current in the cils 16 and 17 are controlled and the mirror 1 is displaced, allowing to track the pickup accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reproducing device for optical information recording and two-disk bodies, and more specifically, to a drive control device for a rotating mirror provided in an optical pickup system.

Optical video discs and digital audio discs (
Hereinafter, these optical information recording disk bodies will be simply referred to as disks. ) is equipped with an optical pickup that irradiates a light beam from a laser light source in a spot shape toward the recording surface of the disk through an objective lens, and detects the reflected or transmitted light. The optical pickup is provided with several servo control means to prevent erroneous detection due to surface runout or eccentricity of the disk. Namely, it is automatic focus control of the objective lens as the disc oscillates, tracking control so that the light spot always traces the planned information track, and Speed error correction control in the tangential direction to the information track caused by (jitter correction control)
It is. Among these, automatic focus control is performed by moving the objective lens and its lens barrel in the front and back direction along the optical axis, but the following two methods are known for tracking control and jitter correction control. ing.

(1) A first rotating mirror called a tangential mirror and a second rotating mirror called a tracking mirror are arranged in the light path from the laser light source to the objective lens, and the first rotating mirror The optical spot on the disk surface is moved in the tangential direction of the information track, while
A light spot is swung in the radial direction of the disk by a second rotating mirror to cause the beam to accurately follow the information track.

(2) Move the lens barrel holding the objective lens in the axial direction (
In addition to automatic focus control by moving in the Z-axis direction),
The lens barrel itself is oscillated in the X-axis direction and the Y-axis direction so that automatic focus control, tracking control, and jitter correction control can be performed in one device (see, for example, Japanese Patent Laid-Open No. 54-24002).

In that case, in the conventional example (1) above, separate control devices corresponding to automatic focus control, tracking control, and jitter correction control are required, and the optical system becomes complicated and the assembly The drawback was that adjustment was difficult. On the other hand, according to the method (2) above, the so-called three-axis correction can be performed with one device, so although the drawback regarding the above (1) is solved, the controlled member including the objective lens and its lens barrel is As the mass increases, practical problems such as mechanical resonance arise.

In addition, since the X-motion coil, Y-axis coil, and Z-axis circumferential coil must be arranged within a structurally narrow magnetic gap, extremely high assembly precision is required, and leakage magnetic flux increases. Contains problems.

The present invention was made in order to solve the problems of the conventional device described above, and its purpose is to provide an optical system having an optical pickup capable of performing tracking control and jitter correction control using a single rotating mirror. An object of the present invention is to provide a reproducing device for a digital information recording disk.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the accompanying drawings.

A rotating mirror 1 in this playback device is placed in the optical path of an optical pickup that includes a laser light source and an objective lens (not shown), and is rotated in both the X-axis direction and the Y-axis direction by a drive control device 2. It is configured so that tracking control and jitter correction control of the light beam emitted from the laser light source can be performed simultaneously. That is,
The drive control device 2 has a cross-shaped permanent magnet 3 configured as a Heath plate, and two pairs of columnar yokes 4, 5 and 6, 7 are arranged at each end of the permanent magnet so as to stand up almost vertically. installed. In this case, yoke 4,
The tips of pole pieces 5, 6, and 7 are bent inwardly to form pole pieces 4/L 5/, 61.7/, but pole pieces 4', 5', and 6/7/ are distributed in planes with different heights.

Further, on the permanent magnet 3, a single-point supported pivot 9 and a cylindrical inner yoke 10 made of a highly permeable material are provided via a support base 8 made of an electrical insulator such as ABS resin. ing. The pivot 9 is made of hardened steel wire or the like and is provided at the center of the device. The cylindrical yoke 10 is arranged concentrically with respect to the pivot bearing 9, and each of the above-mentioned pole pieces 4/, s/ and 6/
, 7/ are provided with pole pieces 11 and 12 for forming a uniform DC magnetic gear between them.

In addition, in this embodiment, the pole pieces 11 and 12 are in the groove 1.
However, the protrusions may be formed only in the portions facing the pole pieces 4/, 5/, 6', and 7'. A cylindrical coil bobbin 14 is provided in association with the magnetic gap thus formed between each pole piece.

This coil bobbin 14 has a light reflecting plate formed in a thin plate shape for forming the above-mentioned rotating mirror 1 on its upper surface, and on the other hand, a pivot receiver 15 that cooperates with the pivot 9 is formed in its cylinder. has been done. This pivot receiver 15 is preferably made of hardened steel, ruby, etc., but it may also be made of rubber so that vibrations are absorbed by its damper action. .17 are each wound independently. In this case, the first coil ]6 is a pair of pole pieces 4/
, 5/P is wound in relation to a magnetic cap formed between the pole piece 11 of the cylindrical yoke 10 facing it, and the second coil 17 is wound around the pair of pole pieces 6/P. , 7/ and the cylindrical yoke 1 facing it
It is wound in relation to the magnetic gap formed between the pole piece 12 of 0 and the pole piece 12 of 0. Note that the first coil 1
6 and the second coil 17 are wound vertically symmetrically across an imaginary horizontal plane including the support point of the pivot 9, and the coil bobbin 14 is made of non-conductive material such as synthetic resin that does not cause eddy current loss. Preferably, it is made of a soft material.

Next, the present invention will be explained in detail. For convenience of explanation, in FIG. 1, the direction of an imaginary line connecting pole pieces i/, s/ is taken as the X axis, and pole pieces 6/, -t/
Let the direction of the imaginary line connecting the two be the Y axis. Also, pole piece,
i/, 6/ are north poles, pole pieces 5', 7/ are south poles, and the magnetic flux coming out of the north pole pieces, s/, 6/, flows from the opposing pole pieces 11, 12 to the cylindrical yoke 10. A uniform DC magnetic cap is formed between the pole pieces 5/ and 7/ of the S pole from the opposite side. Therefore, when a control current is supplied to the first coil 16, the electromagnetic force generated in the coil causes the rotary mirror 1 to rotate together with the coil bobbin 14 in the X-axis direction with the Y-axis passing through the pivot 9 as the rotation axis.

On the other hand, when a control current is supplied to the second coil 17, the electromagnetic force generated in the coil causes the rotary mirror 1 to rotate together with the coil bobbin 14 in the Y-axis direction with the X-axis passing through the pivot 9 as the rotation axis. . However, in reality, control currents are applied to the first and second coils 16 and 17 at the same time, and as a result, the rotating mirror 1 is rotated in the direction of the combined vector of the electromagnetic forces generated in those coils. Become. Here, if the X-axis direction is taken as the tracking control direction of the optical spot on the disk (not shown), and the Y-axis direction is taken as the jitter correction control direction, both of these controls can be performed simultaneously with this rotary mirror ~l.

As is clear from the above description of the embodiments, according to the present invention, tracking control and jitter correction control of the light beam emitted from the laser light source can be performed by one rotating mirror. Therefore, in the optical pickup of this playback device, it is only necessary to arrange one rotary mirror in the light beam path from the laser light source to the objective lens, and compared to the conventional example (1) described above, the optical system and The configuration of the control device itself can be made simpler. On the other hand, it is relatively superior in terms of practicality compared to the conventional example (2), in which each servo control system for focus control, tracking control, and jitter correction control is incorporated into the objective lens device. In other words, in the conventional example, three coils for three-axis correction must be placed in a narrow space within the objective lens device, which makes the structure complicated and requires a large space including the objective lens and its lens barrel. Controlling a mass body is actually quite difficult. In contrast, in this invention, although a rotating mirror is required, only one is required, and the configuration is simple, and the mass of the mirror that is the controlled object is quite small, so it is possible to achieve high precision. Control becomes possible. In addition, according to this drive control device, since the cylindrical yoke is provided inside the coil bobbin, leakage magnetic flux can be reduced as much as possible. By forming the pole piece, reliable operation and separation of X-axis control and Y-axis control can be obtained.

Note that, unlike the above embodiment, it goes without saying that the rotary mirror may be attached to the coil bobbin at an appropriate angle.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a rotating mirror drive control device used in the optical pickup system of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a sectional view taken along the line X-X in FIG. be. In the figure, 1 is a rotating mirror, 2 is a drive control device, 3 is a permanent magnet, 4 to 7 are yokes, 9 is a pivot, 10 is a cylindrical yoke, and 14 is a coil bobbin. Patent applicant Takuya Ohara, patent attorney representing Audio-Technica Co., Ltd.
g! , nai-] Procedural amendment (method) 1 Case description 1982 Patent No. 1 No. 152310'/8″O
SS, t, Reproducing device for scientific information recording disks 3, Relationship with the case of the person making the amendment Patent applicant 4, Agent 102 8 Translated the detailed description of the amendment and the drawings (no change in content) submit. Written amendment to the above procedure (
Spontaneous) January 9, 1987, Director General of the Japan Patent Office Minoru Karasu 1) Haru Kikudono 1, Incident Indication 1986 4I To 1 No. 152310, Issue 11
04th name Optical information recording disk. Reproduction device 3, relationship with the case of the person making the amendment Patent applicant 4, agent 102-5, date of amendment order (voluntary) 1

Claims (1)

[Scope of Claims] A light beam from a light source is reflected by a rotating mirror and is incident on an objective lens, and the light beam is irradiated in a spot shape toward a recording surface of an optical information recording disk through the objective lens. A reproducing device including an optical pickup, comprising: a cylindrical coil bobbin that supports the rotating mirror and has first and second coils wound in parallel to each other at different height positions; and a cylindrical coil bobbin that swings the coil bobbin. two pairs of outer yokes disposed opposite each of the first and second coils and spaced apart from each other by 90 degrees; and interposed between the outer yokes. a cylindrical inner yoke disposed inside the coil bobbin and having a pole piece facing each of the outer yokes; An optical information recording disc body characterized in that it has a rotating mirror drive control device that swings the rotating mirror in an arbitrary direction about the fulcrum of the bearing means by an electromagnetic force generated in the coil. playback device.