JPH11259904A - Optical disk device, device and method for detecting optical disk information used for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk information detecting device detecting optical disk information in an objective lens and an optical disk existing in an optical contact state and an optical disk device using it. SOLUTION: An objective lens 13a and an optical disk 11 are in an optical contact state, and a numerical aperture is constituted to 1 or above. At this time, a light source 22 irradiating a light beam L1 on the optical disk 11 through the objective lens 13a, a photodetcting means 23 detecting return light from the optical disk 11 and a processing circuit 24 detecting optical disk information recorded on a recessed part 11a formed on the optical disk 11 based on the detection signal of the return light from the photodetecting means 23 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical disk device for recording or reproducing an optical disk signal, and an optical disk information detecting device used for the optical disk device.

[0002]

2. Description of the Related Art Conventionally, recording and reproduction of information signals on an optical disk such as a magneto-optical disk (MO) are performed by an optical disk device. This optical disk device
A rotation drive unit such as a spindle motor for rotating the optical disc, and a light source are irradiated with light from the light source through an optical system including an objective lens, and return light from the signal recording surface of the optical disc is passed through the objective lens. An optical pickup for detecting by an optical detector, a biaxial actuator for supporting the objective lens movably in two axial directions, that is, a focusing direction and a tracking direction, and generating a magnetic field based on a signal to be recorded on the optical disk. And a recording magnetic head.

[0003] Thus, in the case of reproduction, a light beam emitted from a light source of an optical pickup is focused on a signal recording surface of an optical disk via an optical system. The return light beam from the optical disk is separated from the light beam emitted from the light source by the optical system and guided to the photodetector. Thus, the information signal recorded on the optical disc is reproduced based on the detection signal from the photodetector. At this time, the light beam emitted from the light source follows the displacement of the optical disk in a direction orthogonal to the surface direction of the optical disk generated due to the warpage of the optical disk or the like, and is focused on the signal recording surface of the optical disk. Thus, the position of the objective lens in the optical axis direction is adjusted.

At the same time, the position of the spot on the optical disk of the light beam emitted from the light source follows the eccentricity of the optical disk and the meandering of the track formed on the optical disk in the direction orthogonal to the optical axis of the objective lens. The position is adjusted. In the case of recording, a light beam emitted from a light source is focused on a signal recording surface of an optical disk by an objective lens via an optical system. In this case, the light beam from the light source has a high output, and the information signal is magnetically recorded on the signal recording surface of the optical disk based on the magnetic field generated by the recording magnetic head.

[0005]

By the way, by increasing the density of the optical disk, the distance D between the optical disk and the surface of the objective lens on the optical disk side is brought into an optical contact state, and the aperture ratio (NA) of the optical system is changed. The so-called near-field optical recording technology has been developed in which the recording density is increased by setting the value of (1) to 1 or more. In practical use of such near-field optical recording technology, it is important to maintain the optical contact state at the distance D. For this reason, it has been attempted to hold the objective lens at a predetermined distance from the surface of the optical disk by applying the technology of a head slider in a magnetic disk recording / reproducing apparatus, a so-called hard disk drive.

However, in the case of a hard disk drive, when recording / reproducing a signal to / from a magnetic disk as a recording medium, the signal recording / reproducing intensity increases in proportion to the increase in the distance between the magnetic head and the magnetic disk. In the case of a magneto-optical disk device, if the distance between the objective lens and the optical disk increases,
The light quantity does not decrease in proportion to the increase in the distance due to the interference with the return light from the optical disc, but the increase or decrease in the light quantity does not decrease in proportion to the increase in the distance due to the interference with the return light from the raw optical disc. Does not decrease, but the amount of light increases or decreases. For this reason, the S / N ratio fluctuates with the fluctuation of the distance D, and there is a problem that the recording / reproducing performance is reduced.

Further, at the time of recording, a change in the distance D between the objective lens and the optical disk greatly changes the light amount of the spot on the signal recording surface of the optical disk, and in some cases, a writing error occurs. Therefore, there is a problem that the reliability of the recorded data is impaired. Further, in the near-field optical recording technique, there is a problem that it may be difficult to reproduce optical disk information such as address information by a phase pit method due to the above-mentioned fluctuation in the amount of return light.

In view of the above, the present invention provides an optical disk information detecting device for detecting optical disk information with respect to an objective lens and an optical disk in an optical contact state, and an optical disk device using the same. The purpose is.

[0009]

According to the present invention, there is provided an optical lens and an optical disk having an aperture ratio of 1 or more in an optical contact state. A light source that irradiates the optical disc through the light source; a light detection unit that detects return light from the optical disc; and a light beam that is recorded in a recess formed in the optical disc based on a detection signal of the return light from the light detection unit. And a processing circuit for detecting the optical disk information present.

Further, according to the present invention, there is provided an optical lens and an optical disk having an aperture ratio of 1 or more in an optical contact state, wherein a light beam is emitted from a light source through the optical lens. This is achieved by irradiating the optical disk, detecting return light from the optical disk, and detecting optical disk information recorded in a recess formed in the optical disk based on the detected amount of return light.

Further, according to the present invention, there is provided a rotating drive means for rotating an optical disc, and an optical contact state with the rotating optical disc so that an aperture ratio becomes 1 or more. An optical pickup that irradiates light through a held optical lens and detects return light from a signal recording surface of the optical disc by a photodetector through the optical lens, and the optical lens can be moved in two axial directions. A two-axis actuator, a signal processing circuit for generating a reproduction signal based on the detection signal from the photodetector, and an objective lens of the optical pickup based on the detection signal from the photodetector. A servo circuit for moving in the axial direction, light detecting means for detecting return light from the optical disc, and the light based on a return light detection signal from the light detection means. It is achieved by providing a disc information detecting apparatus comprising a processing circuit for detecting the optical disc information recorded in a recess formed in disc.

According to the above arrangement, in the optical disk device or the like, the light beam from the light source of the optical pickup reaches the signal recording surface of the optical disk via the optical lens, and the return light from the optical disk is again transmitted via the optical lens. Incident on the light detecting means. Here, the light detecting means detects the return light and outputs a detection signal based on the light amount. As a result, the processing circuit detects the optical disk information recorded in the concave portion of the optical disk based on the detection signal for the return light.

Here, when the light beam spot is formed in the concave portion of the optical disk, the detection signal of the light detecting means fluctuates greatly due to an increase in the distance between the optical disk and the optical lens. Therefore, the presence of the concave portion can be easily detected. When the processing circuit also detects the distance between the optical lens and the optical disc based on the detection signal of the return light, the change in the distance is monitored based on the detected distance between the optical lens and the optical disc. By doing so, the recording error of the optical disk can be grasped in advance, and the reliability of the recorded data is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. still,
Since the embodiments described below are preferred specific examples of the present invention, various technically preferred limitations are added.
The scope of the present invention is not limited to these embodiments unless otherwise specified in the following description.

FIG. 1 shows the configuration of an optical disk device incorporating the first embodiment of the optical disk information detecting device according to the present invention. In FIG. 1, an optical disk device 10
Are a spindle motor 12 as a driving means for rotatingly driving the optical disc 11 which is a magneto-optical disc, an optical pickup 13, and a feed motor 14 as the driving means.
And a recording magnetic head 15 as a recording magnetic head for recording information on the optical disk 11. Here, the drive of the spindle motor 12 is controlled by the system controller 16 and the servo control circuit 18 and is rotated at a predetermined rotation speed.

The optical disk 11 can select and reproduce a plurality of types of optical disks.
Therefore, for example, not only a magneto-optical disc but also a read-only optical disc such as a compact disc (CD) can be reproduced as an optical disc. The optical pickup 13 irradiates the signal recording surface of the rotating optical disk 11 with light through an objective lens (not shown), and performs recording magnetic recording based on signals from a signal demodulator and an error correction circuit 17. The signal is recorded together with the head 15,
Further, it detects the return light from the signal recording surface and outputs a reproduction signal based on the return light to the signal demodulator and the error correction circuit 17.

Thus, the recording signal demodulated by the signal demodulator and the signal demodulation unit of the error correction circuit 17 is error-corrected through the error correction unit, and when the optical disk device 10 is used for data storage of a computer. Is transmitted to an external computer or the like via the interface 19. As a result, the external computer and the like
1 can be received as a reproduction signal. When the optical disk device 10 is for audio, the error-corrected recording signal is subjected to digital / analog conversion by the D / A converter of the D / A, A / D converter 20, as indicated by the dotted line. And output as an audio signal.

A feed motor 14 for moving the optical pickup 13 to a predetermined recording track on the optical disk 11, for example, is connected to the optical pickup 13. The servo control circuit 18 controls the spindle motor 12 and the feed motor 14, and controls the focusing direction and the tracking direction of the biaxial actuator that holds the objective lens of the optical pickup 13. Further, the optical disk device 10 includes an optical disk information detecting device 21 for detecting the optical disk information by a groove provided on the optical disk 11 where the optical disk information is recorded.

FIG. 2 shows a first embodiment of the optical disk information detecting apparatus according to the present invention. In FIG. 2, the optical disk information detection device 21 in the case shown in FIG.
1 and a light beam L1 from the light source 22
Detecting means 2 for detecting return light from optical disk 11
3 and a processing circuit 24 to which a detection signal from the light detection means 23 is input.

On the other hand, as shown in FIG. 2, the optical disk 11 has a concave portion 11a such as a groove or a dent in which optical disk information such as address information is recorded on the surface. The depth of the concave portion 11a is selected to be, for example, about １ ／ of the wavelength λ of light used in the light source of the optical pickup. Optical disc 11 having such a recess 11a
Can be easily formed by, for example, injection molding, but is not limited thereto. For example, an optical disk using a glass substrate or an aluminum substrate may be used. Thus, the light beam L1 from the light source 22 reaches the optical disc 11 via the objective lens 13a, and the return light of the light beam L1 is incident on the objective lens 13a again.

As shown in FIG. 2, the upper side of the objective lens 13a, that is, the light source side is formed as a convex shape, and the lower side, that is, the optical disk side, is formed as a substantially flat surface. Further, the objective lens 13a is mounted on a slider 25.
The objective lens 13a is maintained in an optical contact state with the optical disk 11 by traveling with a constant floating amount with respect to the surface of the optical disk 11 by the air lubrication surface 25a formed on the optical disk 11 side. It has become.

The processing circuit 24 detects the concave portion 11a of the optical disk 11 by a large change based on the detection signal from the light detecting means 23, and further records the data based on a small change of the detection signal in the concave portion 11a. The optical disk information such as the address information is detected.
The light source 22 can use the light source of the optical pickup 13 of the optical disk device 10 as it is, and the light detecting means 23 can use the light detector of the optical pickup 13.

The optical disk device 10 according to the present invention is configured as described above. In FIG. 2, the light beam L1 from the light source is focused on the signal recording surface of the optical disk 11 from above via the objective lens 13a. Is done. Then, the return light from the optical disk 11 again enters the light detection means 23 via the objective lens 13a, and the return light related to the light beam L1 is detected. At this time, the light beam L1 is
a through the objective lens 13a when the light enters the portion of the optical disk 11 other than the concave portion 11a.
Air gap to is small. On the other hand, as shown in FIG. 4, when the light beam L1 is incident on the concave portion 11a of the optical disk 11 through the objective lens 13a, the distance from the objective lens 13a to the optical disk 11 by the depth of the concave portion 11a. The air gap increases.

Therefore, the amount of the returning light of the light beam L1 detected by the light detecting means 23 is different based on the difference in the air gap. This is because the amount of return light is determined based on the refractive index and NA of the objective lens 13a, the configuration and the refractive index of the optical disk, the wavelength of light from the light source 22, and the distance from the light source 22 to the light detecting means 23. This is because the distance from the light source 22 to the light detecting means 23 differs by the difference of the air gap. Accordingly, the processing circuit 24 monitors the detection signal of the light detection means 23 for the return light of the light beam L1, and detects that the concave portion 11a of the optical disk 11 is present when the detection signal greatly fluctuates. It is possible. Thus, when the concave portion 11a of the optical disk 11 is detected, the processing circuit 24 detects a small change in the detection signal from the light detecting means 23, thereby detecting optical disk information such as address information recorded in the concave portion 11a. be able to.

Further, the processing circuit 24 can detect an air gap between the optical disk 11 and the optical lens 13a based on a detection signal from the light detecting means 23. This is based on the fact that the detection signal substantially decreases as the air gap increases. By constantly monitoring the air gap detected in this way, when the air gap fluctuates, the fluctuation is immediately detected, and the occurrence of a recording error on the optical disk due to the air gap fluctuation. Is predicted without reproducing the recorded optical disk, and the reliability of the recorded data is improved.

FIG. 3 shows a second embodiment of the optical disk information detecting device according to the present invention. In FIG. 3, the optical disk information detecting device 30 has basically the same configuration as the optical disk information detecting device 20 shown in FIG. 2, but the optical contact state of the objective lens 13a with the optical disk 11 is maintained. The configuration is different only in that the operation is performed by the actuator 31 instead of the slider. In this case, the actuator 31 is constituted by a coil formed to circulate around the optical axis of the objective lens 13a.

According to the optical disk information detecting device 30 having such a configuration, the objective lens 13a is held in an optical contact state with the optical disk 11 by the actuator 31, and the light beam L1 Is irradiated on the optical disk 11 through the objective lens 13a, and the return light from the optical disk 11 is
3, the concave portion 11a of the optical disk 11 is detected as in the case of the distance detecting device 20 shown in FIG.

In the embodiment described above, the depth of the concave portion of the optical disk 11 is selected to be about λ / 8, but is not limited to this and may be smaller. Further, in the above-described embodiment, the magneto-optical disk device that performs recording and reproduction of the magneto-optical disk has been described. However, the present invention is not limited to this, and other types of optical disks employing the near-field optical recording technology, for example, a phase change recording type The present invention can be applied to an optical disk device for a read-only optical disk such as an optical disk and a compact disk (CD).

As described above, in an optical disk device or the like, the light beam from the light source of the optical pickup reaches the signal recording surface of the optical disk via the optical lens, and the return light from the optical disk is again transmitted via the optical lens. Incident on the light detecting means. Here, the light detecting means detects the return light and outputs a detection signal based on the light amount. As a result, the processing circuit detects the optical disk information recorded in the concave portion of the optical disk based on the detection signal for the return light.

Here, when the light beam spot is formed in the concave portion of the optical disk, the detection signal of the light detecting means fluctuates greatly due to an increase in the distance between the optical disk and the optical lens. Therefore, the presence of the concave portion can be easily detected. When the processing circuit also detects the distance between the optical lens and the optical disc based on the detection signal of the return light, the change in the distance is monitored based on the detected distance between the optical lens and the optical disc. By doing so, the recording error of the optical disk can be grasped in advance, and the reliability of the recorded data is improved.

[0031]

As described above, according to the present invention, optical disk information can be detected for an objective lens and an optical disk in an optical contact state.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a configuration of a magneto-optical disc device incorporating a first embodiment of an optical disc information detecting device according to the present invention.

FIG. 2 is a schematic sectional view showing a configuration of an optical disk information detecting device in the magneto-optical disk device of FIG.

FIG. 3 is a schematic sectional view showing a configuration of a second embodiment of the optical disk information detecting device according to the present invention.

FIG. 4 is an enlarged plan view showing a relationship between a groove as a concave portion on the optical disk and a spot in the optical disk information detecting device of FIG. 2;

[Explanation of symbols]

10 optical disk device, 11 optical disk, 1
2 ... spindle motor, 13 ... optical pickup, 14 ... feed motor, 15 ... recording magnetic head, 16 ... system controller, 17 ... signal modulator / demodulator and error correction circuit, 18 ... ..Servo control circuit, 19 interface, 20 D / A, A
/ D converter, 21... Optical disk information detecting device, 22
... Light source, 23 ... Light detection means, 24 ... Slider, 24a ... Air lubrication surface, 25 ... Processing circuit, 3
0 ... optical disk information detecting device, 31 ... actuator

Claims (6)

[Claims] 1. An optical lens and an optical disk having an aperture ratio of 1 or more in an optical contact state, wherein: a light source for irradiating a light beam to the optical disk through the optical lens; Light detection means for detecting return light; and a processing circuit for detecting optical disk information recorded in a concave portion formed on the optical disk based on a detection signal of return light from the light detection means. An optical disk information detection device characterized by the following. 2. The distance detection device according to claim 1, wherein the processing circuit detects a distance between the optical lens and the optical disk based on the detection signal of the return light. 3. The distance detection according to claim 1, wherein the optical lens is held in an optical contact state by a slider that holds a constant flying height by an air lubrication surface with respect to the surface of the optical disk. apparatus. 4. The distance detecting apparatus according to claim 1, wherein the optical lens is held in an optical contact state with a surface of the optical disk by an actuator. 5. An optical lens and an optical disk having an aperture ratio of 1 or more in an optical contact state, wherein a light beam is emitted from the light source to the optical disk via the optical lens, and An optical disc information detection method, comprising detecting return light, and detecting optical disc information recorded in a concave portion formed on the optical disc based on the detected light quantity of the return light. 6. A rotation driving means for rotating and driving an optical disc, and an optical lens which is in an optical contact state with the rotating optical disc and which is held at an aperture ratio of 1 or more. An optical pickup that irradiates and detects a return light from a signal recording surface of the optical disc by a photodetector through the optical lens; a biaxial actuator that supports the optical lens so as to be movable in biaxial directions; A signal processing circuit that generates a reproduction signal based on a detection signal from a detector; a servo circuit that moves an objective lens of the optical pickup in two axial directions based on a detection signal from the photodetector; A light detecting means for detecting return light from the optical disc; and a light beam recorded on a concave portion formed on the optical disc based on a detection signal of the return light from the light detection means. Optical disk apparatus characterized by comprising a disc information detecting apparatus comprising a processing circuit for detecting the optical information is.