JPH11283257A - Optical disk device and focus servo method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely perform focus servo even when an optical lens is held in optical contact with an optical disk. SOLUTION: The light converging means 41 of an optical pickup is composed of a first optical convergence system 43 and a second optical convergence system 44 in this order from the side of an optical disk 1, and the first optical convergence system 43 is held at a prescribed distance in the focus direction by a holding means 43b and is provided with a reflection part 46 out of the optical axis of the surface on the side of the optical disk 1. Shifting of the second optical convergence system 44 is controlled in the focus direction, and based on the light of a side beam reflected by the reflection part of the first optical convergence system, a servo circuit performs focus servo control of the light converging means by controlling the shifting of the second optical convergence system in the focus direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus for recording or reproducing an optical disk signal and a focus servo method therefor.

[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 disc device irradiates a rotating drive means such as a spindle motor for rotating the optical disc with light from a light source via a light focusing means to the rotating optical disc, and focuses the return light from the signal recording surface of the optical disc. An optical pickup for detecting by a photodetector via a means, a biaxial actuator for supporting a light focusing means movably in a biaxial direction, that is, a focusing direction and a tracking direction, and a magnetic field based on a signal to be recorded on an optical disk. And a magnetic head that generates

In the case of reproduction, a light beam emitted from a light source of an optical pickup is condensed on a signal recording surface of an optical disk via a light focusing means. The return light beam from the optical disc is separated from the light beam emitted from the light source via the light focusing means 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 (focus servo). At the same time, the position of the light beam emitted from the light source in the direction orthogonal to the optical axis of the objective lens is adjusted so that the position of the spot on the optical disk follows the eccentricity of the optical disk or the meandering of the track formed on the optical disk. (Tracking servo).

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 a light focusing means. In this case, the light beam from the light source has a high output, and based on the magnetic field generated by the magnetic head,
Magnetic recording of information signals is performed on the signal recording surface of the optical disk.

[0005]

By the way, by increasing the density of an optical disk or the like, the distance between the optical lens and the optical lens disposed between the optical disk and the light focusing means is shortened, and the optical distance is reduced. A so-called near-field optical recording technique has been developed in which the recording density is increased by setting the NA of the optical system to 1 or more in a contact state.

In practical use of such near-field optical recording technology, it is important to maintain an optical contact state at the above distance. It is also important to accurately adjust the focal position of the optical system to a position where an engineering contact state is maintained. However, since an interference phenomenon occurs between the optical disk and the optical lens, it is difficult to separate stray light due to such interference and other factors. Therefore, the focus servo of the light focusing means and the optical focusing means and the optical lens It is not easy to adjust the optical focus position to the signal recording surface of the optical disc.

In particular, when the focus position (focus) is deviated during data recording or reproduction, a signal for adjusting the distance between the optical disk and the optical lens and a focal position are set on the end face of the optical lens. Since it is not easy to separate from the signal for adjustment, it takes much time to return to the normal focus state, and the possibility that the optical lens and the optical disk collide during the adjustment increases. There was a problem that would.

In view of the above, an object of the present invention is to provide an optical disk apparatus and an optical disk apparatus that can reliably perform focus servo even when an optical lens is held in an optical contact state with an optical disk. It is intended to provide a focus servo method.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided a rotating drive unit for rotating an optical disk, and an optical beam is irradiated to the optical disk via a light focusing unit.
An optical pickup for detecting return light from a signal recording surface of an optical disc by a photodetector via a light focusing means, a signal processing circuit for generating a reproduction signal based on a detection signal from the photodetector, and a photodetector A servo circuit for moving the light focusing means of the optical pickup in two axial directions based on the detection signal from the optical pickup, wherein the optical pickup includes a light splitting means for splitting the light beam into a main beam and at least one side beam. The light focusing means has a first converging optical system and a second converging optical system in order from the optical disk side, and the first converging optical system is A reflection unit is provided at a position that is held at a predetermined distance and is off the optical axis on the optical disk side surface, and the second converging optical system is moved and adjusted in the focus direction. In addition, the servo circuit moves and adjusts the second converging optical system in the focusing direction based on the reflected light of the side beam by the reflecting portion of the first converging optical system, and adjusts the focus servo of the light focusing means. This is achieved by an optical disk device having a configuration for performing the operation.

According to the first aspect of the present invention, of the first and second converging optical systems constituting the light converging means, the first converging optical system is held at a predetermined distance from the surface of the optical disk. You. On the other hand, based on the detection signal from the photodetector of the optical pickup due to the return light, a focus error signal is generated by a method such as an astigmatic method, so that the servo circuit By moving and adjusting the system in the focus direction, focus servo of the light focusing means is performed.

[0011] In this case, the focus servo of the light focusing means is performed based on the return light reflected by the reflector provided on the optical disk side of the first converging optical system. Therefore, since this return light does not pass between the optical disk and the first converging optical system, it is not affected by interference generated at the interface between the optical disk and the first converging optical system. Thereby, even when the first converging optical system is in an optical contact state with the surface of the optical disc, for example, the first converging optical system is affected by interference generated between the first converging optical system and the optical disc. Therefore, an accurate focus servo is performed.

When the reflecting section is provided by a step formed on the lens surface of the optical lens, a thick reflecting film such as a dielectric multilayer film is selected as the reflecting section by the step. In addition, for example, a protective film such as an oxide film can be formed on the surface of a reflective film made of aluminum or the like, thereby increasing the degree of freedom in designing the reflective portion.

[0013] The servo circuit, based on the step of the optical lens, includes: a portion between the photodetector and the reflecting portion;
When the focus servo of the light focusing means is performed so as to correct the offset corresponding to the difference in the distance between the optical detector and the optical disk, the difference in the distance is measured in advance. Thus, accurate focusing on the signal recording surface of the optical disk is performed.

The light beam is split so that the side beam reaches the reflecting portion, and the split side beam and each return light of the main beam that passes through the optical lens and reaches the signal recording surface of the optical disk. If the measuring means is provided to detect the distance between the optical lens and the optical disc by detecting the distance, the divided light beam and the light transmitted through the step area are measured by the measuring means. The distance between the lens surface on the optical disk side of the first converging optical system and the optical disk surface is measured by detecting the light amount difference between the main beam transmitting near the axis and the main beam.

[0015]

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 embodiment of a magneto-optical disk drive to which the tracking servo method according to the present invention is applied. In FIG. 1, a magneto-optical disk drive 1A
Are a motor 2 disposed on the rotation axis of the magneto-optical disk 1, a head 3 disposed on the recording surface side of the magneto-optical disk 1, a head amplifier 4 connected to the head 3, and a focus matrix circuit. 5, tracking matrix circuit 8, phase compensation circuits 6, 9, amplifiers 7, 10
Contains.

The motor 2 functions to rotate the magneto-optical disk 1 at a predetermined speed. The head 3 functions to write a recording signal supplied from a predetermined device (not shown) to the magneto-optical disk 1, read the recording signal written to the magneto-optical disk 1, and output the read signal as an MO reproduction signal. . Also, the head 3 has a function of outputting a servo signal used for tracking and focus adjustment of laser light applied to the magneto-optical disk 1 to the focus matrix circuit 5 and the tracking matrix circuit 8 via the head amplifier 4. I do.

The focus matrix circuit 5 functions to calculate a focus error signal from the servo signal supplied from the head 3 and output it to the phase compensation circuit 6. The phase compensation circuit 6 includes the focus matrix circuit 5
The phase compensation of the supplied focus error signal is performed, and the phase compensated signal is output via an amplifier 7 to a focus actuator (described later) provided in the head 3. Tracking matrix circuit 8
Functions to calculate a tracking error signal from the servo signal supplied from the head 3 and output it to the phase compensation circuit 9. The phase compensating circuit 9 compensates the phase of the tracking error signal supplied from the tracking matrix circuit 8, and converts the phase compensated signal into the head 3 via the amplifier 10, for example, a tracking actuator (for example, a voice coil) provided in the head 3. (Not shown).

FIG. 2 shows a detailed configuration of the head 3. 2, the head 3 includes a magnetic field generator 3A for writing a recording signal to the magneto-optical disk 1 and reading the recording signal written to the magneto-optical disk 1, and an optical pickup 3B. Magnetic field generator 3A
Includes an amplifier 36 and a magnetic field modulation coil 42.
The optical pickup device 3B includes a semiconductor laser (light source) 2
0, grating 21, collimator lens 22, shaping prism 23, beam splitters 24, 26, 32, magneto-optical head 25, lenses 27, 31, cylindrical lens 28, photodetectors 29, 33, 34, 1/2 wavelength plate 30, differential amplifier 35 and objective lens (light focusing means) 4
1 is provided.

The semiconductor laser 20 functions to generate a laser beam of a predetermined wavelength and make it incident on the collimator lens 22. The grating 21 is a diffraction grating that diffracts incident light, and divides a light beam from the semiconductor laser 20 into at least three light beams, that is, a main beam composed of zero-order diffracted light and a side beam composed of plus or minus first-order diffracted light. I do. Therefore, another division element such as a hologram element may be used as long as at least three light beams can be divided and generated. The collimator lens 22 functions to arrange the laser light from the semiconductor laser 20 into a parallel light beam and to make the laser light incident on the beam splitter 24 via the shaping prism 23. The beam splitter 24 includes the shaping prism 2
3 functions to make the laser light from the objective lens 41 incident on the objective lens 41 and reflect the laser light (return light) from the objective lens 41 toward the beam splitter 26.

The magneto-optical head unit 25 has an objective lens 41 of the optical pickup device 3B, a magnetic field modulation coil 42 of the magnetic field generator 3A, and the like. When reproducing data, the objective lens 41 allows the laser beam from the beam splitter 24 to be reproduced. The recording layer 1b formed on the substrate 1a of the magneto-optical disk 1 is irradiated, and the return light reflected by the recording layer 1b is incident on the beam splitter 24. And a magnetic field having an intensity corresponding to the recording signal supplied to the irradiation position of the laser beam.

The beam splitter 26 reflects a part of the return light reflected by the beam splitter 24 at a predetermined ratio to make it enter the lens 27, and transmits a part of the return light to form a half-wave plate. Through the lens 3
It functions so as to be incident on the light source 1. The lens 27 functions to convert return light (parallel rays) from the beam splitter 26 into convergent light and to make it incident on the photodetector 29 via a cylindrical lens 28 that gives astigmatism. The photodetector 29 has a light receiving portion divided into four parts, and functions to convert the laser light incident on each light receiving portion into an electric signal and output the electric signal to the head-up 4 as a servo signal.

The lens 31 functions to convert the return light from the half-wave plate 30 into convergent light and make it incident on the beam splitter 32. The beam splitter 32 includes a lens 31
A part of the convergent light from the light source is transmitted and made incident on the photodetector 33, and a part of the convergent light is reflected and the light
4 so as to be incident. The photodetector 33 and the photodetector 34 function to output an electric signal corresponding to the amount of return light from the beam splitter 32 to the differential amplifier 35, respectively. The differential amplifier 35 includes a photodetector 33
And the output of the photodetector 34 is calculated, and the calculation result is output to a predetermined device (not shown) as an MO reproduction signal.

FIG. 3A shows a first configuration example of the magneto-optical head unit 25. In the figure, an objective lens 41 as a light focusing means is composed of a first converging optical system 43 and a second converging optical system 44 in order from the magneto-optical disk 1 side. The first converging optical system 43 is composed of, for example, one convex lens, and is held at a predetermined distance from the surface of the magneto-optical disk 1 as described later.

The second converging optical system 44 is composed of, for example, a single convex lens, and a focusing actuator provided in the head 3 based on the focus error signal calculated by the tracking matrix circuit 8 described above. By means of 45, the movement is adjusted in the focus direction, and the focus servo is performed.

Here, in the first converging optical system 43, for example, as shown in FIG. 3A, an optical lens (front lens) 43a and a slider 43b are integrally formed. The optical lens 43a is configured as a so-called hemispheric lens in which the lens surface on the optical disk side shown in the lower part of FIG. 3A is flat, and the lens surface on the opposite side is spherical. The optical lens 43a has a projection 43c at the center of the lower plane, and the end face of the projection is formed as a plane perpendicular to the optical axis. A step 46a is provided between the projection and its peripheral area. This step 46a
Is selected to be, for example, about 波長 of the wavelength λ of light used in the light source of the optical pickup. The concave portion, which is a region around the convex portion 43c, has a step with respect to the convex portion, and has a reflective portion 46 in a part thereof as described later. Further, in the optical lens 43a, the magnetic field modulation coil 42 (not shown in FIG. 3) is attached to a region around a convex portion on the optical disk side (a region as a concave portion recessed by a step).

The slider 43b introduces air from the inclined surface 43d between the air lubricating surface 43e and the magneto-optical disk 1 based on the dynamic pressure generated by the rotation of the magneto-optical disk 1, and generates a magneto-optical signal. The disk 1 travels at a constant flying height with respect to the surface. Thereby, the optical lens 4
3a is held in an optical contact state with the magneto-optical disk 1.

In such a configuration, after the laser beam from the beam splitter 24 is converged by the second converging optical system 44 of the objective lens 41, the first converging optical system 43
Is converged by the optical lens 43a of FIG. In this case, the focus servo of the objective lens 41 is performed by the focus actuator 45 based on the focus error signal from the amplifier 7. Further, at the time of data recording, a magnetic field corresponding to a recording signal supplied from a predetermined device is generated by the magnetic field modulation coil 42, and is applied to the irradiation position of the laser beam by the optical pickup 3B.

Here, the focus servo is performed by the side beam L2 or L3 of the main beam L1 and the side beams L2 and L3 split by the grating 21 via the second converging optical system 44 of the objective lens 41. Incident on the optical lens 43a of the first converging optical system 43,
The return light reflected by the reflector 46 provided on the lens surface on the optical disk side is detected by the photodetector 29 to generate a focus error signal. Based on the focus error signal, a focus actuator 45 is generated. To adjust the movement of the second converging optical system 44 in the focus direction.

In such a magneto-optical disk device 1A,
At the time of data reproduction, the laser beam from the beam splitter 24 is applied to the second converging optical system 4 of the objective lens 41 in FIG.
4 and converged by the second converging optical system 44, and further converged by the first converging optical system 43.
The main beam L1 converges on the recording layer 1b of the magneto-optical disk 1. Then, the return light reflected by the recording layer 1b is again incident on the beam splitter via the objective lens 41, is converted into an electric signal by the photodetectors 33 and 34, and the MO reproduction signal is converted by the differential amplifier 35. Generated
Data is reproduced.

On the other hand, the side beams L2 and L3 are converged by the first converging optical system 43 and then reflected by the reflecting portion 46, and the returned light is incident on the beam splitter again via the objective lens 41. The focus matrix circuit 5 and the tracking matrix circuit 8 generate a focus error signal and a tracking error signal.

Here, the focus servo of the objective lens 41 is performed based on the focus error signal. That is, the slider 43b supporting the first converging optical system 43 of the objective lens 41 is held by the air lubrication surface at a constant flying height with respect to the surface of the magneto-optical disk 1, and the second converging optical system is used. The focus servo is performed by moving and adjusting the system 44 in the focus direction by the focus actuator 45. Also,
At the time of data recording, a magnetic field having an intensity corresponding to the recording signal supplied via the amplifier 36 is applied by the magnetic field modulation coil 42 to the irradiation position of the laser beam on the magneto-optical disk 1,
Data is recorded.

In this case, the focus servo of the objective lens 41 moves the slider 43 with respect to the surface of the magneto-optical disk 1.
b based on the return light from the reflector 46 provided in the first converging optical system 43 held at a certain distance by the floating of b.
This is performed by detecting a focus error signal. For this reason, even when the first converging optical system 43 is disposed close to the magneto-optical disk 1, the side beams L2 and L3 are not reflected by the first converging optical system 43 and the magneto-optical disk 1. Since it is not affected by interference between the first and second surfaces, an accurate focus error signal is detected,
Focus servo is performed with high accuracy. Here, the focus servo causes the focus matrix circuit 5 to correct the focus error signal so as to cancel an offset due to a step between the convex portion 43c of the optical lens 43a of the first converging optical system 43 and the surroundings. By doing so, it is done more accurately. That is, the focus servo is accurately performed by canceling the difference corresponding to the distance between the reflection section 46 and the signal recording surface of the magneto-optical disk 1 from the detection value based on the focus error signal. Is realized by using the measuring device 50 of FIG.

That is, the magneto-optical disk drive 1A is
Preferably, the first converging optical system 43 and the magneto-optical disk 1
A measuring device 50 as shown in FIG. 3B is provided as a measuring means for measuring the distance between. This measuring device 50
Is a main beam L1 and a side beam (two side beams L4 and L5 on both sides of the main beam in the case of the drawing), which are different from the above-described side beams L2 and L3. Here, the side beams L2 and L3 are called a first side beam for servo,
It is distinguished from the side beams L4 and L5 for distance measurement for correction. ), And light detecting means 52 for detecting return light of the main beam L1, side beams L4, and L5 from the light source 51 from the magneto-optical disk 1, respectively.
And an arithmetic circuit 53 to which each detection signal from the light detection means 52 is input.

As a result, of the light beams from the light source 51, the main beam L1 is
After the light enters the optical lens 43a of the first converging optical system 43, the light exits from the convex portion 43c and reaches the magneto-optical disk 1, and the return light of the main beam L1 again enters from the convex portion 43c of the optical lens 43a. I do. After the side beams L4 and L5 are incident on the optical lens 43a of the first converging optical system 43 from the second converging optical system 44, the side beams L4 and L5
The light exits from the area other than the reflecting portion 46 of the optical lens 3c and reaches the magneto-optical disk 1, and the return light of the side beams L4 and L5 is incident again on both sides of the convex portion 43c of the optical lens 43a. Thus, the optical path of the main beam L1 and the side beams L4 and L5 is configured such that the distance between the optical lens 43a and the magneto-optical disk 1, that is, the so-called air gap is different.

The arithmetic circuit 53 calculates the difference between the detection signals from the light detecting means 52, and further calculates the distance between the optical lens 43a and the magneto-optical disk 1 from the difference signal. .

As the light source 51, the semiconductor laser 20 of the optical pickup 3B is used. As the light detecting means 52, the light detector 29 of the optical pickup 3B is used as it is. There are various methods for dividing the two side beams L4 and L5. That is, a dividing unit different from the dividing unit for dividing the first side beams L2 and L3 may be added, or the first side beams L2 and L3 may be divided.
And the second sideomes L4, L5 can be generated by one dividing means. As one method, another light splitting means such as an additional grating different from the grating 21 and a hologram element for generating the second side beam may be provided. By using such a dividing means, for example, the main beam L1 is divided into the second side beams L4 and L5.

Here, the division of the side beams L4 and L5 is preferably performed by using a grating 2 as shown in FIG.
This is performed in a direction substantially perpendicular to the optical axis and the direction of division. Although such division complicates the arrangement of the divided light receiving portions of the photodetector 29, a grating in which mutually orthogonal grooves having different depths are formed instead of the grating 21 in which interference grooves are formed in one direction. By using
It can be easily realized. On the other hand, the side beam L
The division of 4, 4 may be preferably performed in the same direction as the division direction of the grating 21, as shown in FIG. In this case, for example, plus or minus second-order diffracted light or the like is used as the side beams L2 and L3 for detecting the focus error signal, so that the amount of return light of the side beams L2 and L3 decreases. But,
It is not necessary to separately provide the dividing means to obtain the first and second sideomes, and the arrangement of the divided light receiving portions of the photodetector 29 may be simple.

By using such a measuring device 50, the main beam L1 is projected onto the convex portion 4 of the optical lens 43a.
Since the light enters the magneto-optical disk 1 through 3c and then again enters the optical lens 43a from the convex portion 43c, the air gap from the optical lens 43a to the magneto-optical disk 1 is small. On the other hand, the side beams L4 and L5 enter the magneto-optical disk 1 through both sides of the convex portion 43c of the optical lens 43a, and enter the optical lens 43a again from both sides of the convex portion 43c. The air gap from the lens 43a to the magneto-optical disk 1 is large. Therefore,
The amount of return light of the main beam L1 and the side beams L4, L5 detected by the light detecting means 52 will be different based on the difference in the air gap. This is because the amount of return light is determined by the refractive index of the optical lens 43a and the numerical aperture (N
A), configuration and refractive index of magneto-optical disk, and light source 5
1 and the distance from the light source 51 to the light detection means 52. Therefore, the main beam L
This is because the difference between the return light amounts of 1 and the side beams 4 and 5 corresponds to the distance from the light source 51 to the light detecting means 52.

Thus, the difference between the detection signal of the light detecting means 52 with respect to the return light of the main beam L1 and the side beams L4, L5 is obtained, whereby the optical lens 43a in the convex portion 43c of the optical lens 43a and the magneto-optical disk 1 are obtained.
Is calculated. Thus, in the above-described focus servo, by performing offset correction in accordance with the distance calculated in this manner, when the distance changes, the focus servo can immediately respond to the change. Thus, the focus servo is performed with higher accuracy. Further, by monitoring the signal of the light detecting means 52 with respect to the return light of the main beam L1 and the side beams L4 and L5, it is possible to detect a case where the slider 43b jumps due to some impact. This further improves the reliability.

As described above, according to the above-described embodiment, the focus servo of the light focusing means is performed based on the return light reflected by the reflector provided on the optical disk side of the first converging optical system. Therefore, since this return light does not pass between the optical disk and the first converging optical system,
It is not affected by interference generated at the interface between the optical disc and the first converging optical system. Thereby, even when the first converging optical system is in an optical contact state with the surface of the optical disc, for example, the first converging optical system is affected by interference generated between the first converging optical system and the optical disc. Therefore, an accurate focus servo is performed. In particular, when the focus is lost during data recording or reproduction, the first converging optical system is held at a predetermined distance with respect to the surface of the optical disk. Since the focus servo of the first focusing optical system is performed based on the return light from the provided reflection unit, the return to the normal focus state is easily and quickly performed. The risk of collision between the system and the optical disk is avoided.

FIG. 6 shows a second configuration example of the magneto-optical head unit in the magneto-optical disk device 1A. 6, the magneto-optical head unit 60 has basically the same configuration as that of the magneto-optical head unit 25 shown in FIG. 3, and the same components are denoted by the same reference numerals and redundant description is omitted. The following description focuses on the differences. The configuration is different only in that the optical lens 43a maintains an optical contact state with the magneto-optical disk 1 only by the actuator 61, not by the slider 43b. 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 magneto-optical head section 60 having such a configuration, the optical lens 43a is held in an optical contact state with the magneto-optical disk 1 by the actuator 61. As a result, the main beam L1 and the side beams L2, L3, L4, L5 enter the optical lens 43a of the first converging optical system 43 from the second converging optical system 44, and the main beam L1 and the side beams L4, L5.
Is irradiated on the magneto-optical disk 1 from the lower surface of the optical lens 43a, and the return light from the optical disk 11 is detected by the photodetectors 33 and 34 and the photodetector 52, respectively, so that the MO reproduction signal is detected. At the same time, the distance between the optical lens 43a and the magneto-optical disk 1 is detected. The side beams L2 and L3 are
The focus error signal is detected by the reflected light reflected by the reflecting portion 46 of the optical lens 43a and detected by the photodetector 29, and the focus servo of the objective lens 41 is controlled based on the focus error signal. Done. Accordingly, the same operation and effect as in the case of the magneto-optical head unit 25 shown in FIG. Optical lens 4
Accurate focus servo is performed without being affected by interference between the optical disk 3a and the magneto-optical disk 1.

In the above-described embodiment, the optical lens 43a of the first converging optical system 43 has the convex portion 43c on the lens surface on the magneto-optical disk side. It may be configured as a plane.
If the whole is configured as one plane,
Since the distance between the optical lens 43a and the magneto-optical disk 1 cannot be measured by the measuring device 50, the measuring device 50 is omitted, or another measuring device is provided.

In the above-described embodiment, the magneto-optical disk device for recording / reproducing the magneto-optical disk 1 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, it is apparent that the present invention can be applied to an optical disk device for a read-only optical disk such as a phase change recording type optical disk and a compact disk (CD).

[0046]

As described above, according to the present invention, even when the optical lens is held in an optical contact state with the optical disk, the focus servo is reliably performed and the reliability is improved. Is improved.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a configuration of an embodiment of a magneto-optical disk drive to which the present invention is applied.

FIG. 2 is a schematic diagram showing a configuration of a head in the magneto-optical disk device of FIG.

FIG. 3A is a schematic diagram illustrating an optical configuration of a first configuration example of a magneto-optical head unit in the head of FIG. 2;
FIG. 2B is a block diagram illustrating a configuration example of a measuring device of the magneto-optical disk device of FIG. 1.

FIG. 4 is a schematic plan view showing one configuration example of a relationship between an optical lens and each beam in the magneto-optical head unit in FIG.

FIG. 5 is a schematic plan view showing another configuration example of the relationship between the optical lens and each beam in the magneto-optical head unit of FIG.

FIG. 6 is a schematic diagram illustrating an optical configuration of a second configuration example of the magneto-optical head unit in the head of FIG. 2;

[Explanation of symbols]

1A ... magneto-optical disk device, 1 ... magneto-optical disk, 3 ... head, 3A ... magnetic field generator, 3B
..Optical pickups, 25, 60 ... magneto-optical head part, 41 ... objective lens, 42 ... magnetic field modulation coil, 43 ... first converging optical system, 43a ... optical lens, 43b ... Slider, 43c ... Protrusion, 44
... second converging optical system, 45 ... focusing actuator, 46 ... reflector, 50 ... measuring device,
51: light source, 52: light detection means, 53: arithmetic circuit, 61: actuator.

Claims (8)

[Claims] A rotating drive unit for rotating the optical disk; and a light beam irradiating the optical disk through a light focusing unit, and returning light from a signal recording surface of the optical disk to a photodetector through the light focusing unit. An optical pickup for detecting the optical pickup, a signal processing circuit for generating a reproduction signal based on the detection signal from the photodetector, and a light focusing means of the optical pickup in the biaxial direction based on the detection signal from the photodetector. A servo circuit for moving the optical beam; the optical pickup includes a light splitting unit that splits a light beam into a main beam and at least one side beam; An optical system and a second converging optical system, wherein the first converging optical system is held at a predetermined distance in the focus direction by holding means. And a reflecting portion at a position off the optical axis of the surface on the optical disk side, the second converging optical system is moved and adjusted in a focusing direction, and the servo circuit is configured to An optical disc device, wherein a second converging optical system is moved and adjusted in a focusing direction based on light reflected by a reflecting portion of the converging optical system to perform focus servo of a light focusing unit. 2. The optical disk device according to claim 1, wherein the first converging optical system is held in an optical contact state with a surface of the optical disk. 3. The optical disk device according to claim 1, wherein said holding means is a biaxial actuator. 4. The optical disk device according to claim 2, wherein said holding means is a slider which holds a constant flying height by an air lubrication surface. 5. The optical disk device according to claim 1, wherein the reflection section is provided on a step surface formed by a step formed on a lens surface of the optical lens on the optical disk side. 6. An offset corresponding to a difference in a distance between the photodetector and the reflecting portion and a distance between the photodetector and the optical disk based on the step of the optical lens. 6. The focus servo of the light focusing means is performed so as to correct the following.
An optical disk device according to claim 1. 7. The light beam is split so that the side beam reaches the reflecting portion, and each of the split side beam and the main beam that reaches the signal recording surface of the optical disk through the optical lens. 7. The optical disk device according to claim 6, further comprising a measuring unit configured to detect a distance between the optical lens and the optical disk by detecting return light. 8. An optical disc is irradiated with light through a light focusing means of an optical pickup, return light is detected by a photodetector of the optical pickup, and a focus error signal is detected based on a detection signal from the photodetector. A focus servo method for moving the light focusing means of the optical pickup in the focus direction based on the focus error signal, wherein the light focusing means sequentially performs the first focusing from the optical disc side. An optical system and a second converging optical system, wherein the first converging optical system is held at a predetermined distance in the focus direction by a holding means, and is deviated from the optical axis of the optical disk side surface. A reflecting portion at the position, and the second converging optical system moves in the focus direction based on the reflected light from the reflecting portion of the first converging optical system. By being integer, the focus servo method and performing the focus servo of the optical focusing means.