JPH03142723A - Tilt servo mechanism - Google Patents

Abstract

PURPOSE:To always make incident light without inclination even when a pickup is inclined at the time of tilt servo by providing an optical path, which optical axis is made orthogonal to the radial direction of a disk, in one part of an optical path in an optics at least, and supporting the pickup turnably with the optical axis of this orthogonal optical path as a turning center axis. CONSTITUTION:The optics is equipped with the optical path, which optical axis is made orthogonal to the radial direction of the disk, in one part at least and a supporting mechanism 9 supports a pickup 6 with the optical axis of the orthogonal optical path as the turning center axis. In such a way, when the title servo is executed by supporting the pickup 6 with the optical axis of the optical path, for which the optical axis is made orthogonal to the radial direction of the disk, as the turning center axis, the inclination of an optical axis O is same when inclining the pickup 6 and accordingly, the light without inclination is made incident to an objective lens 16 even at the time of the tilt servo. Thus, even when the pickup 6 is inclined, the light without inclination is made incident to the objective lens 16.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a tilt servo mechanism in an optical information recording disc playing device.

BACKGROUND TECHNOLOGY In an optical information recording disc performance device, if the information recording disc (hereinafter simply referred to as a disc) has warpage due to changes over time, the warping may occur depending on the irradiation position of the information reading light beam emitted from the pickup. The information recording surface of the disk is tilted with respect to the optical axis of the light beam. As a result, the track pitch between adjacent recording tracks becomes narrower with equal deflection, so if the beam spot diameter on the information recording surface is kept constant, it becomes easier to be influenced by the bit information of adjacent recording tracks, resulting in crosstalk. This will lead to an increase in The influence of this crosstalk appears as a noise component in the video signal reproduced from the disc, resulting in image deterioration. In order to improve this kind of performance deterioration, the inclination of the optical axis of the information reading light beam with respect to the information recording surface of the disk is detected, and the optical axis of the light beam is always perpendicular to the information recording surface. A so-called tilt servo is performed to adjust the tilt of the pickup.

Incidentally, in recent years, pickups with a built-in semiconductor laser as a light source have become mainstream, but for example, in a device that reads recorded information on a master disc, a He -N
A pickup is used that uses an e-laser or the like as a light source and takes in laser light from this fixed light source.

In this way, in a pickup using a fixed light source, only the pickup 6 is provided movably in the radial direction of the disk D, as shown in FIG. The optical path of the incident light is changed to a substantially right angle by a reflecting mirror 15 and guided to an objective lens 16. In such a configuration, when performing tilt servo, if the pickup 6 is tilted by an angle θ around point A on the optical axis of the incident light, the optical axis O of the reflected light at reflection #J15 will be tilted as shown in FIG. Since it is tilted by 2θ, the objective lens 16
Off-axis light centered on the axis of inclination θ will be incident, resulting in a decrease in the intensity of the light emitted from the pickup 6.

SUMMARY OF THE INVENTION [Object of the Invention] Therefore, an object of the present invention is to provide a tilt servo mechanism that allows light to enter an objective lens without tilting even if a pickup is tilted.

[Structure of the Invention] The tilt servo mechanism according to the present invention is a pickup that is movable in the radial direction of the disk and that changes the optical path of incident light from the outside to a substantially right angle and irradiates the information recording surface of the disk. an information recording disc performance device comprising a fixed light source and an optical system that guides the light emitted from the fixed light source to the pickup as the incident light, the pickup being rotatable within a plane including the central axis of rotation of the disc; A tilt servo mechanism includes a support mechanism supported by a support mechanism, and a drive means for rotating a pickup, and is configured to rotate the pickup to adjust the angle of the optical axis of the irradiated light with respect to the information recording surface, The optical system includes at least a part of an optical path in which the optical axis is orthogonal to the radial direction of the disk, and the support mechanism supports the pickup with the optical axis in the orthogonal optical path as a rotation center axis.

[Operation of the Invention] In the tilt servo mechanism according to the present invention, the optical axis is included in at least a part of the optical path of the optical system that guides the light emitted from the fixed light source to the pickup, and the optical axis is perpendicular to the disk radial direction. By rotatably supporting the pickup with the optical axis as the center axis of rotation, even if the pickup is tilted, light without tilting is incident on the objective lens.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic perspective view showing an embodiment of the present invention. In the figure, a carriage 1 is provided so as to be movable along a guide rail (not shown) in the radial direction of the disk. For example, the carriage l is driven in a straight line by a carriage drive mechanism 5, which uses a rotary motor 2 as a drive source and includes a rack 3 attached to the carriage body so as to extend along the direction of movement of the carriage l, and a pinion gear 3 meshed with the rack 3. Driven.

A pickup 6 is rotatably supported on the carriage 1 by a support mechanism 9 consisting of a rotation shaft 7 fixed to one side of the carriage 1 and a bearing 8 for the rotation shaft in a plane including the central axis of rotation of a disk (not shown). It is provided. The pickup 6 is driven by, for example, a rotary motor 1o fixed to the carriage 1, and rotated by a tilt mechanism 13 consisting of a gear 11 fixed to the free end of the rotation shaft 7 and a pinion gear 12 meshed with the gear 11. It moves me. The drive signal for the rotary motor 10 is supplied with the detection output of a known tilt sensor (not shown) that detects the inclination angle of the information recording surface of the disk with respect to the optical axis 0 of the pickup 6.

A fixed light source (not shown) such as a He-Ne laser is provided, for example, outside the movement range of the carriage 1 in the movement direction of the carriage 1 (disc radial direction). The light emitted from this fixed light source in the disk radial direction changes its optical path approximately at right angles by a reflecting mirror 14 fixed on the carriage 1, and then enters the pickup 6. The light incident on the pickup 6 is guided to the objective lens 15 after its optical path is changed roughly at a right angle by the reflecting mirror 15 .

In this configuration, the optical axis of the optical path emitted from the fixed light source 4 and reaching the pickup 6 at the stage where it enters the pickup 6 is perpendicular to the radial direction of the disk, and the support mechanism 9 of the pickup 6 supports this incident light. It is configured to support the pickup 6 with the optical axis as the rotation center axis.

In this way, in the support mechanism 9 of the pickup 6, when performing tilt servo by supporting the pickup 6 with the optical axis in the optical path orthogonal to the disk radial direction as the rotation center axis, the pickup 6 is When tilted by the angle θ, the tilt of the optical axis O is also θ, so
Even during tilt servo, light without tilt is incident on the objective lens 16.

FIG. 2 is a schematic perspective view showing another embodiment of the present invention,
In the figure, parts equivalent to those in FIG. 1 are given the same reference numerals. In the figure, a carriage 1 carries a pickup 6 and is movably provided on a tilt base 21 along a guide rail (not shown). The threaded part 2
It is designed to be driven linearly by a drive mechanism 24 consisting of three parts. The tilt base 21 is rotatably supported at one end by a support mechanism 27 consisting of a rotation shaft 25 and its bearing 26. The tilt base 21 is rotatably supported by a support mechanism 27 consisting of a rotation shaft 25 and its bearing 26, and is driven by a rotation motor 10, a wedge gear 28 and a worm gear 29 meshed with the rotation motor 10. In the tilt mechanism 30, the cam follower 31 fixed to the other end of the tilt base 21 contacts the cam surface 28a of the wedge-shaped gear 28 and moves up and down in accordance with the rotation of the gear 28, thereby being rotated. It has become.

In such a configuration, light is emitted from the fixed light source in a direction perpendicular to the radial direction of the disk, and the optical path of this light is changed in the radial direction of the disk by the reflecting mirror 31 fixed to the tilt base 21. .33, the optical path is sequentially changed approximately at right angles, and the light is guided to the pickup 6 as light in the disk radial direction. In this optical path, the optical axis of the light incident on the reflection mirrors 31 and 33 is perpendicular to the disk radial direction, and the support mechanism 27 of the tilt base 21 rotates the optical axis of the light incident on the reflection mirror #A31, for example. It is configured to support the tilt base 21 as a dynamic center axis.

In this way, in the support mechanism 27 of the tilt base 21, when performing tilt servo by supporting the tilt base 21 with the optical axis in the optical path orthogonal to the disk radial direction as the rotation center axis, the tilt servo is When the pickup 6 is tilted by an angle θ by rotating the base 21, the inclination of the optical axis O is also θ. Therefore, as in the case of the above embodiment, the objective lens 16 has an angle of θ even during tilt servo. This means that light will be incident.

In each of the above embodiments, the configurations of the drive mechanisms 5, 24 and tilt mechanisms 13, 30 of the carriage 1 are merely examples, and the present invention is not limited to these, and various configurations may be used. .

As described in detail, in the tilt servo mechanism according to the present invention, the optical axis is perpendicular to the disk radial direction in at least a part of the optical path of the optical system that guides the light emitted from the fixed light source to the pickup. Since the pickup is rotatably supported with the optical axis in the orthogonal optical path as the central axis of rotation, even if the pickup is tilted during tilt servo, the objective lens will always receive steady light. It will be incident.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing one embodiment of the present invention, FIG. 2 is a schematic perspective view showing another embodiment of the present invention, FIG. 3 is a configuration diagram showing a conventional example, and FIG. It is a figure which shows the relationship of the inclination angle of the pickup and the optical axis O in the structure of a figure. Explanation of symbols of main parts 1... Carriage 5.24... Carriage drive mechanism 6...
・Pickup 9, 27...Support mechanism 13
．． 30...Tilt mechanism

Claims (1)

[Scope of Claims] A pickup that is provided movably in the radial direction of an information recording disk and that changes the optical path of incident light from the outside to a substantially right angle and irradiates it toward the information recording surface of the information recording disk. , an information recording disc playing device comprising a fixed light source and an optical system that guides light emitted from the fixed light source to the pickup as the incident light, wherein the pickup is arranged in a plane including a rotation center axis of the information recording disc. and a drive means for rotating the pickup, and by rotating the pickup, the angle of the optical axis of the irradiated light with respect to the information recording surface is adjusted. a tilt servo mechanism, wherein the optical system includes at least a part of an optical path in which the optical axis is perpendicular to the radial direction of the disk, and the support mechanism supports the pickup with the optical axis in the orthogonal optical path as a rotation center axis. The tilt servo mechanism is characterized by: