JPH03225637A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a recording and reproducing device in which recording density is enhanced by providing a 1st detection means and a 2nd detection means and respectively detecting a land part and a groove part formed on an optical disk. CONSTITUTION:The optical disk 10 is constituted of a recording layer 10a and a disk substrate 10b. A track is circumferentially formed on the recording layer 10a which is formed on the surface of one side of the disk substrate 10b and a signal is formed as a pit 15 on the track. Namely, the optical disk 10 has the grove part 13 and the land part 11. The optical head 1 exists, for example, under the optical disk 10 which is rotated at a high speed and whose linear velocity is constant and the optical disk 10 is irradiated with light beams from two emitted light sources through light beam irradiation ports 3 and 5 from the underside of the optical disk 10. Then, the light beam 3a of on side is adjusted to follow the track formed on the land part 11 and the light beam 5a of the other side is adjusted to be formed on the groove part 13 so that the signal may be recorded and reproduced.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to optically recording, reproducing, or erasing signals related to information. The present invention relates to a recording and reproducing device capable of reproducing data.

(Prior art) Conventionally, signals are recorded by irradiating a light beam such as a laser beam.
As optical disks that can be reproduced and erased, there are generally known types such as a magneto-optical type, a phase change type, and an organic dye recording film type.

Further, these optical disks usually have a guide groove formed therein, and signals are recorded only in one of the four parts forming the guide groove, that is, the groove part, or the convex part, that is, the land part.

That is, the guide groove in a normal optical disc has a land width of 0.8 μm and a groove width of 0.8 m, and the width of the guide groove is set to 1.6 μm. The groove depth was set depending on the wavelength of the light beam used. In other words, the optical depth of the guide groove is set to be 1/4 of the wavelength λ of the optical beam because the optical beam is diffracted at the interface between the land and the groove and it is necessary to reduce the amount of reflected light that returns to the objective lens. has been selected. For example, when a semiconductor laser is used as a light beam source, the groove depth is 0.05 to 0.11 mm.
It became about m.

Furthermore, in recent years, it has been proposed to use multiple light beams to perform recording and erasing on the same track, respectively. ZB-4 or 2a-
(See ZB-5).

(Problems to be Solved by the Invention) As mentioned above, in conventional optical disk recording and reproducing devices, signals are recorded only in the groove portion or land portion of the optical disk, which reduces the recording density. This was a constraint on improving the quality of the product.

The present invention has been made in view of the above circumstances, and its purpose is to provide a recording and reproducing device that can record on both the land and groove portions of an optical disc, thereby dramatically increasing the recording density. There is a particular thing.

(Means for Solving the Problems) In order to achieve the above object, the present application provides a light emitting source that generates a light beam, an optical means for guiding the destination beam generated from the light emitting source to an optical disk, and a light emitting source that generates a light beam. a first detecting means for detecting an optical change caused when the laser beam guided by the optical disk is reflected at a groove portion of the optical disk; and a second detection means for detecting the received optical change.

(Function) In the optical disk recording and reproducing apparatus of the present application, the first detection means and the second detection means are configured to respectively detect the land portion and the groove portion formed on the optical disk. It is possible to reproduce signals on the tracks formed in each of the groove portions, or to perform recording and erasing on the tracks.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a diagram showing how recording is performed on a recording medium according to an embodiment of the optical recording/reproducing apparatus of the present invention. Further, in this embodiment, an optically writable phase change optical disk (hereinafter simply referred to as an optical disk) 10 is used as a recording medium.
This will be explained using an example.

The optical disk 210 is composed of a recording layer 10a on which signals as information are recorded, and a disk substrate 10b made of a transparent material such as glass, polycarbonate, or PMMA (transparent acrylic resin). On the recording layer 10a formed on one surface of the recording layer 10a, tracks are generally formed in a circumferential manner at intervals of 1.6 knots t1n, and signals are formed as pin nodes 15 on these tracks.

That is, the optical disc 10 has a groove (bottom) portion 13 forming a pregroove and a land portion 11.
The substrate 10b is attached to this land portion 11, that is, the toranoa.
(A phase-change recording mark, that is, a pit 15, is formed by the light beam incident from pJ, and recording is performed.

Next, an outline of the optical head 1 will be explained with reference to FIG.

The optical head 1 is located below an optical disk 10 that is rotated at high speed, for example, at a constant linear velocity, by a rotational drive source such as a spindle motor (not shown), and receives light beams from two light emitting sources from below the optical disk 10. Each light beam is irradiated toward the optical disc 10 from the light beam irradiation port 3.5. Furthermore, the optical disc 1 is
It records and erases signals for 0, and also receives reflected light from the optical disc to read and reproduce the signals recorded on the optical disc 10. Further, at this time, during reproduction, a light beam with a constant intensity is output, and during recording, a light beam whose intensity is modulated according to the signal is output.

Further, the optical head 1 is configured to be movable in the tracking direction T by a linear motor (not shown), and can be precisely driven downward in the tracking direction by a tracking servo mechanism. This allows access to the track at a predetermined address and access to the optical disc 1.
Tracking of zero eccentricity is performed accurately and precisely.

Similarly, by a focusing servo mechanism (not shown), the optical disc 1, which normally exists within a range of several hundred μm, is
Focusing operation for a surface runout of 0 is performed precisely.

Next, the configuration of the optical head 1 and its peripheral devices will be explained with reference to FIG. Further, for ease of explanation, the two light beam systems constituting the optical head 1 are constructed in a substantially concave shape, so the description will be made using one light beam system as an example.

The semiconductor laser 21 is a light emitting source that generates a laser beam as a light beam, and the wavelength λ of the laser beam generated from the semiconductor laser 21 is, for example, 670 nm or 83 nm.
It is set to 0nm.

Laser light generated by this semiconductor laser 21 and emitted radially enters a collimator lens 23, is converted into parallel light, and is output to a polarizing beam splitter 25.

The polarizing beam splitter 25 splits, transmits, and reflects the incident laser beam, and makes the transmitted light and the reflected light polarized light orthogonal to each other.

This polarizing beam splitter 25 is connected from the semiconductor laser 21 side.
The laser beam incident on the optical disc 1 is transmitted through the polarizing beam splitter 25 and further converged by the objective lens 27.
The focus is focused on the recording layer 10a of 0.

The objective lens 27 is provided with an objective lens actuator 27a that moves the objective lens in the optical axis direction during focusing. The laser beam focused on the recording layer 10a performs recording, reproduction, or erasing on the recording layer 10a.

On the other hand, the laser beam reflected by the recording layer 10a enters the polarizing beam splitter 25 via the objective lens 27, and is directed into the direction perpendicular to the optical axis of the light beam, that is, the quarter-wave plate 2
reflected in one direction.

This one quarter wavelength plate eliminates the return light from the detection system, which will be described later, and thereby prevents an adverse effect on the semiconductor laser 21 and the optical disk 10.

The tracking servo machine side and the force sink search machine side that constitute the above-mentioned detection system will be explained below.

The laser beam reflected by the polarized beam vine 25 is applied to a second polarized beam splitter 33 via a quarter-wave plate 29 and a lens system 31, which detects defocus, and uses the error signal to adjust the objective lens. A focusing servo error detection system that automatically performs focusing by driving 27 detects the deviation between the beam spot and the track, and uses the error signal to drive various actuators to make the laser beam follow the track. The light is split into a tracking servo error detection system. That is, the polarizing beam splitter 3
The laser beam reflected by 3 and guided to the focusing servo error detection system is changed in shape in a cross section perpendicular to the optical axis of the beam (hereinafter simply referred to as cross-sectional shape) by a cylindrical lens 35, and then enters a detector 37. Ru.

This detector 37 uses a four-split photodetector, and when the cylindrical lens 37 is in focus on the recording layer 10a of the optical disc 10, the cylindrical lens 37
The photodetector is placed at a position where the cross-sectional shape of the laser beam emitted from the photodetector is a perfect circle, with the center of the perfect circle matching the center of the four-part photodetector.

Therefore, when in focus, the signal levels from the four photodetectors are the same. On the other hand, in the out-of-focus state, the position where the cross-sectional shape of the laser beam emitted from the cylindrical lens 35 is a perfect circle is shifted in the optical axis direction, and only the laser beam with an elliptical cross-sectional shape is incident on the 4-split photodetector. Therefore, the outputs of photodetectors on the diagonal are the same, and the outputs of adjacent photodetectors are different. Therefore, when out of focus, an output corresponding to the distance to the optical disk 10 can be obtained from the differential amplifier 13. The objective lens actuator 27a is driven in accordance with this output signal to obtain a focused state.

Further, the laser beam that passes through the polarizing beam splitter 33 and is not guided to the tracking servo error detection system is sent to the detector 41.
is incident on the A two-split photodetector is used as the detector 41, and when the laser beam irradiation position is on one side of the land portion 11 or the groove portion 13, the outputs from the two photodetectors are the same, and the laser beam is split into two. When a portion of the laser beam overlaps the adjacent groove portion 13 or land portion 11, the laser beam is scattered and the output of the photodetector on the side where the portion overlaps decreases (push-pull method).

Therefore, in this embodiment, the light beam system on one side is adjusted to always follow the track formed on the land portion 11, and the light beam system on the other side is adjusted to always follow the track formed on the flute portion 11. The signal recorded on each track is reproduced, or the signal recorded or erased.

Note that any optical system may be selected as the lens system 31 as required and may be omitted. In addition, in this embodiment, since the astigmatism method is adopted for the focus servo, a four-segment photodetector is used as the cylindrical lens 35 and the detector 37, or when the Foucault prism method is adopted, instead of the cylindrical lens 35. A Foucault prism is used for this, a Naifezi and a two-split photodetector are used when the Naifezi method is employed, and a critical angle prism and a two-split photodetector are used when the critical angle detection method is employed.

Similarly, although the push-pull method is used for tracking servo, an appropriate method such as the three-spot method may be used.

Next, a second embodiment according to the present invention will be described with reference to FIG. 4.As is clear from the relationship between the tracks of the optical disk and the laser beam irradiation position shown in FIG. The irradiation positions of the laser beams are arranged at different radial positions on adjacent tracks.

That is, as shown in FIG. 3, the irradiation position 3b.

5b on the same radius, the distance between the centers of the tracks is usually narrow, for example, 1.6 μm, so simply placing the laser beam exit ports 3.5 close to each other will cause the irradiation positions 3b and 5b to be tracked. However, in this embodiment, the first optical head la having the first detection means and the second optical head la having the first detecting means are The second optical head 1h having a detection means is provided separately and independently, and the irradiation positions of these two optical heads la and lb are shifted to different radial positions of adjacent tracks. The optical disc 10 can be irradiated with laser light from a direction perpendicular to the optical disc 10. This makes it easy to fine-tune the irradiation direction of the two light beams during the manufacturing process and at the time of the optical system 7, and it is also possible to separate the distances in the circumferential direction of the two optical nozzles la and lb from each other. When doing so, the irradiation direction or the relative position of the optical heads 1a, 1b is finely adjusted when the optical nozzles 1a, 1b are located on the outer circumference and when they are located on the inner circumference, respectively.

Next, a third embodiment of the present invention will be described using FIG. 5. In this embodiment, as is clear from the relationship between the tracks of the optical disk and the laser beam irradiation positions shown in FIG. 5, the laser beam irradiation positions are located on the same radius of the tracks 7 that are separated from each other. be. This is the second
For the same reason as in the embodiment, fine adjustment of the irradiation direction to the optical disc 10 can be easily made.

In the embodiments described above, two independent sets of optical systems were used to obtain this light beam system, but the present invention is not limited to this. For example, two semiconductor lasers may be used to generate light beams. The laser beam may be emitted by a set of optical systems using a prism or the like.

[Effects of the Invention] As explained above, according to the optical disc of the present invention, the heights of the recording surfaces of the first tracks and the recording surfaces of the second tracks, which are arranged closely and alternately, are made different. Therefore, it is possible to record signals on both the so-called land part and the blue part, and this optical disc-like recording/reproducing device can distinguish the difference in height of the recording surface of the optical disc and keep it at the same height. Since the signal is detected or recorded, the recording density can be greatly increased.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the general configuration of an optical recording/reproducing apparatus according to an embodiment of the present invention together with a recording medium, FIG. 2 is a diagram showing the configuration of an optical head, and FIG. 4 and 5 are diagrams showing the relationship between the tracks of the recording medium and the irradiation position of the light beam according to other embodiments. 1...Optical head 3.5...Light beam exit port 3a, 5a...Light beam 10...Recording medium (phase change type optical disk) 11...
Land portion 13...Groove portion 15...Hit 21--Semiconductor laser 23...Collimator lens 25.33...Deflection beam splitter 27...Objective lens 29...1/4...Wavelength Plate 37゜41...Detector

Claims (1)

[Claims] (1) A light source that generates a light beam, an optical means that guides the light beam generated from the light source to an optical disk, and a laser beam that is received when the laser beam guided by the optical means is reflected on the land of the optical disk. a first detection means for detecting an optical change caused by the optical disc; and a second detection means for detecting an optical change caused when the laser beam guided by the optical means is reflected at a groove portion of the optical disc. A recording/reproducing device characterized by having the following.