JPH0917079A - Optical disk reproducing device - Google Patents

Abstract

PURPOSE: To obtain a reproduced signal stable in optical axis without deteriorating a disk or changing its structure by holding an optical disk medium between hard plates high in flatness and making their sides opposite to an optical pickup of a laser transmissible material. CONSTITUTION: The optical disk medium 1 and a protective resin layer 3 are loaded onto a lower transmissive type flat surface plate 12 by passing a rotary shaft 8 of a disk stage 9 through them, and are pressed by an upper flat surface plate 11 together with a disk retainer 10. Thus, the optical disk medium 1 is held between the lower transmissive type flat surface plate 12 and the upper flat surface plate 11, and hence rectified in its tilt and corrected into a flat surface. In reproduction, convergent light 6 projected from the optical pickup 4 is transmitted through the lower transmissive type flat surface plate 12 via an objective lens 5 designed to minimize aberration, and is converged on an information recording surface 2 of the optical disk medium 1. Consequently, the device mechanism is simplified, and the regenerative signal stable in the optical axis of laser light can be obtained without deteriorating the optical disk medium and changing its constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing apparatus, and more particularly to a tilt correction of an optical disk medium.

[0002]

2. Description of the Related Art When the tilt of an optical disk medium itself is large, the optical axis of the reflected light of the laser beam focused on the optical disk medium moves, so that a stable reproduction signal may not be obtained. The related art relating to the tilt correction will be described with reference to FIGS.

Japanese Patent Application Laid-Open No. 61-66237 discloses a tilt amount detecting means provided in an optical pickup 4 as shown in FIG. 3, and further controls the inclination of an optical movable table 13 on which the optical pickup 4 is installed. A tilt control unit 17 and a tilt control circuit (not shown) are installed, and the optical movable table 13 is tilted by the tilt control unit 17 based on the detected tilt amount.
Control is performed so that the focused light 6 from the optical pickup 4 is perpendicularly incident on the information recording surface 2 of the optical disk medium 1.

Japanese Patent Application Laid-Open No. 64-64163 discloses that
As shown in FIG. 4, the tilt of the disk medium 1 is corrected by sandwiching it from both sides of the outermost peripheral portion of the optical disk medium 1 loaded in the optical disk reproducing device by a supporting mechanism such as a roller 19.

In Japanese Utility Model Laid-Open Publication No. 59-25630 of FIG. 5, as shown in FIG. 5, a high inertia body 20 is attached in a ring shape to the outer peripheral portion of the optical disk medium 1 and the optical disk medium 1 is tilted by centrifugal force. Has been corrected.

The thickness of the optical disk medium 1 is 0.6
In the case of a thin optical disk medium having a thickness of 1 mm, the optical disk medium 1 is easily deformed due to external stress or the like because the strength of the optical disk medium 1 itself is low. In the case of a single plate, the dependence of the optical head 4 on the focus servo increases, and it is difficult to use the single head. Therefore, as shown in FIG. 6, two thin optical disk media 1 are used, and the protective resin layers 3 are bonded to each other so that the thickness is 1.2 mm.
In some cases, the strength of the optical disk medium is increased to maintain the flatness of the optical disk medium itself.

[0007]

However, in such an optical disc reproducing apparatus, an optical system for detecting a tilt is first required in the tilt servo mechanism in the tilt servo mechanism. The structure of the apparatus is complicated, for example, a circuit system for controlling the optical moving table and a tilt control unit for tilting the optical moving table are required.

Further, in the correction mechanism for supporting the outer peripheral portion, pressure is intermittently applied to the outer peripheral portion of the optical disk medium, and deterioration of the optical disk medium such as peeling of the reflection film may occur in consideration of the number of revolutions during reproduction of the optical disk. High in nature.

In the method of attaching the high inertia body to the outer peripheral portion, the optimum conditions cannot always be satisfied due to the limitation of the weight of the high inertia body and the rotation speed of the optical disk medium at the time of reproduction. Because of the difference, playback can be performed only by a limited playback device.

In the case of a thin optical disk medium having a thickness of 0.6 mm, a recording capacity for both sides is not always required, and there is a case where only one side is sufficient depending on the capacity of recording software. In this case, the other surface has no meaning, such as not recording anything or recording a guide that informs the user that nothing is recorded. However, in order to manufacture an optical disk medium only for single-sided recording, two thin optical disk media are required, and since the lamination is performed, the manufacturing cost is the same as that for double-sided recording.

[0011]

Therefore, according to the present invention, a hard plate having a high degree of flatness is pressed against the loaded optical disk medium from the side opposite to the optical pickup into the optical disk reproducing apparatus, and the surface on which the optical pickup is located. From the side, a hard plate with a high flatness through which the reading laser beam can pass is pressed, and a means for correcting the tilt of the optical disc medium to correct the flat surface state is provided. An optical pickup optically designed to minimize the aberration when the information recording surface of the optical disk medium is focused through a hard plate having a high degree is mounted.

[0012]

1 and 2 show an embodiment of the present invention.
This will be described with reference to FIG.

FIG. 1 is a side view showing a first embodiment of the present invention. Referring to FIG. 1, a first embodiment of the present invention relates to an optical disk reproducing apparatus having a thickness of 1.2 mm.
Optical disk medium 1, an optical pickup 4 for reading a reproduction signal from an information recording surface 2 of the optical disk medium 1, a disk stage 9 rotated by a spindle motor 7, and a disk holding the optical disk medium 1 loaded on the disk stage 9 A holder 10, an upper flat plate 11 sandwiched between the disk holder 10 and the optical disk medium 1 and pressed against the optical disk medium 1;
And a lower transmission type flat plate 12 sandwiched between the optical disk medium 1 and pressed against the optical disk medium 1.

The upper flat plate 11 and the lower transmissive flat plate 12 are made of a material that is not easily deformed by a change in external environment or external stress, such as tempered glass. The transmission type flat plate 12 is preferably made of a material through which the focused light 6 emitted from the optical pickup 4 is transmitted and having a sufficient transmittance to obtain a reproduction signal, for example, tempered glass.

The contact surfaces of the disk stage 9, the lower transmission plane plate 12, the disk medium 1, the upper plane plate 11, and the disk holder 10 are arranged in parallel.

An optical head is attached to the lower part of the optical disk reproducing apparatus via an optical moving table (not shown), and the spindle motor is similarly mounted and fixed in the optical disk reproducing apparatus. A disk stage 9 is mounted on the rotating shaft 8 of the, and a lower transmission type flat substrate is mounted thereon. Similarly, a disc holder 10 is attached to the rotating shaft 8 attached to the upper part of the optical disc reproducing apparatus, and an upper flat plate 11 is attached to the disc holder 10. The upper and lower rotating shafts 8 are arranged on the same axis and are independent from each other.

When the optical disk medium 1 is loaded, the optical disk medium 1 loaded on the lower transmission type flat plate 12 is
The holding position of the optical disc medium 1 is positioned by the center hole (not shown) of the optical disc medium 1 and the rotation shaft 8 of the spindle motor 7 or the rotation shaft 8 of the disc stage. Subsequently, the upper plane plate 11 is pressed against the protective resin layer 3 of the loaded optical disk medium 1 by the pressing means (not shown) together with the disk holder 10.

As a result, the optical disc medium 1 is sandwiched between the lower transmission type flat plate 12 and the upper flat plate 11, and becomes the same plane by the planes of the lower transmission type flat plate 12 and the upper flat plate 11 arranged in parallel. The tilt is corrected by applying pressure to the optical disk medium 1 and the tilt of the optical disk medium 1 itself is corrected to a flat surface.

For signal reproduction, the optical pickup 4
The focused light 6 of the laser light emitted from the optical disk medium 1
However, in the optical disk reproducing apparatus of the present invention, since the laser light is focused through the lower transmission type flat plate 12, the objective lens 5 is optically designed so that the aberration is minimized. Equipped with.

In the optical disk reproducing apparatus of the present invention, the distance between the information recording surface 2 and the objective lens 5 of the optical pickup 4 is separated by the thickness of the lower transmission type flat plate 12, and the NA of the objective lens 5 is maintained. For this purpose, it is necessary to increase the diameter of the objective lens 5, and the burden on an actuator (not shown), which is a driving unit for the objective lens 5 of the optical head 4, may be increased. Therefore, the amount of movement of the objective lens 5 in the focus direction is small, and the use of a large-diameter objective lens can be avoided by reducing the load on the actuator.

In the optical disk medium 1, there are two optical disk media 1 having a thickness of 1.2 mm or 0.6 mm.
There is also an optical disc medium 1 in which one surface and a protective resin layer are bonded to each other to form a single-sided double-sided optical disc. In such a case, the configuration of the upper flat plate 11 is changed and the lower transmission flat plate is changed. By using the same material and plate thickness as those of the optical disk 12, double-sided reproduction can be performed in the optical disk reproducing apparatus of the present invention.

FIG. 2 is a side view showing a second embodiment of the present invention. Referring to FIG. 2, the configuration of the second embodiment of the present invention is the same as that of the first embodiment except that the thickness of the optical disc medium 1 is reduced from 1.2 mm of the conventional one to 0.6 mm of the single plate.
Has been changed to a thin optical disk medium.

The operation is the same as that of the first embodiment.
The tilt of the thin optical disk medium 1 mm is corrected to be flat.

A thin optical disk medium having a thickness of 0.6 mm is thinner than a conventional optical disk medium having a thickness of 1.2 mm and thus has a lower strength, and the lower transmission type flat plate strength can be reduced accordingly. Therefore, in the second embodiment, the plate thickness of the lower transmission type flat plate 12 is set to half of that of the first embodiment. As a result, the NA and the diameter of the objective lens 5 can be increased.

[0025]

As described above, the optical disk reproducing apparatus according to the present invention does not include a mechanism for complicating the structure, does not deteriorate the optical disk medium, or changes the configuration of the optical disk medium itself. With a simple structure in which the optical disk medium is sandwiched between the upper and lower surfaces by a flat plate, the tilt of the optical disk medium is corrected to a flat surface, so that the optical axis of the laser beam reflected by the optical disk medium and returned to the optical pickup is stabilized and excellent reproduction A signal can be obtained.

According to the second embodiment, the thickness is 0.6
Even with a thin optical disk having a thickness of 2 mm, good signal reproduction can be performed in a single-plate state without laminating two optical disks, and the manufacturing cost of an optical disk medium can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view of an optical disk medium loading portion of an optical disk reproducing apparatus according to the present invention.

FIG. 2 is a side view of a thin optical disk medium loading portion of the thin optical disk reproducing apparatus of the present invention.

FIG. 3 is a side view of an optical disc reproducing apparatus equipped with a conventional tilt servo mechanism.

FIG. 4 is a side view of a conventional optical disk reproducing apparatus equipped with an optical disk medium tilt correction mechanism using rollers.

FIG. 5 is a cross-sectional view of a conventional optical disk reproducing apparatus equipped with a tilt correction mechanism for an optical disk medium using a high inertia body.

FIG. 6 is a side view of an optical disk reproducing apparatus loaded with an optical disk medium on which two 0.6 mm thin substrates are bonded.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk medium 2 Information recording surface 3 Protective resin layer 4 Optical pickup 5 Objective lens 6 Focused light 7 Spindle motor 8 Rotation axis 9 Disk stage 10 Disk holding 11 Upper flat plate 12 Lower transmission flat plate 13 Optical movable table 14 Optical movable table Support column 15 Optical movable table tilt control axis 16 Tilt control motor 17 Tilt control unit 18 Support unit 19 Roller 20 High inertia body

Claims (4)

[Claims] 1. An optical disk reproducing apparatus for reading out pit information recorded on a plastic optical disk medium by an optical pickup, wherein the optical disk medium loaded in the optical disk reproducing apparatus is placed on a first plane from the side opposite to the optical pickup. A hard plate is pressed, and a second flat hard plate through which a read laser beam can pass is pressed from a surface side of the optical pickup, and the tilt of the optical disk medium is corrected to a flat state. Optical disc playback device. 2. An optical pickup which is optically designed so that aberration is minimized when the reading laser focuses on the information recording surface of the optical disk medium over the second flat hard plate. The optical disk reproducing apparatus according to claim 1, wherein 3. The optical disk reproducing apparatus according to claim 2, wherein the first flat hard plate is a tempered glass. 4. The optical disk reproducing apparatus according to claim 2, wherein said second flat hard plate is made of tempered glass.