JP4240661B2 - Recording and / or reproducing apparatus and recording and / or reproducing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recording and / or reproducing apparatus and a recording and / or reproducing method for recording and / or reproducing an information signal on a signal recording medium by condensing a laser beam.
[0002]
[Prior art]
In recent years, with the development of technology for digitally recording video data such as moving images and still images on a signal recording medium, a large amount of data has become an object to be recorded on the signal recording medium. Further, in place of generally used magnetic disks such as floppy disks, optical disks such as magneto-optical disks and phase-change optical disks, which have a high recording density and optically record information signals, are becoming widespread.
[0003]
In an optical recording / reproducing technique for optically recording and reproducing information signals to / from a signal recording medium, a reproducing laser beam having a predetermined laser power is condensed on an optical disk as an optical recording medium and reflected. The information signal recorded on the optical disk is read by monitoring the light.
[0004]
When recording an information signal on an optical disk or erasing an information signal recorded on an optical disk, a recording laser beam or an erasing laser beam with a predetermined recording laser power or erasing laser power is used. Is condensed at a desired position on the optical disk. The irradiation of the recording laser beam or the erasing laser beam raises the temperature of the area targeted for recording or erasing on the optical disc, enabling the recording of the information signal and erasing the information signal.
[0005]
In this optical recording / reproducing technique, the density of data recorded on the optical disk depends on the spot diameter of the focused laser beam. That is, the smaller the light spot diameter of the laser beam, the higher the density of data recording and reproduction.
[0006]
The minimum spot diameter of the laser beam condensed by the objective lens is proportional to the wavelength (λ) of the laser beam and inversely proportional to the numerical aperture (NA) of the lens. For this reason, in order to increase the recording density, the wavelength of the light source is shortened and the NA of the objective lens is increased.
[0007]
The numerical aperture (NA) of the objective lens can be expressed as follows using the incident angle (θ) of the collected light and the refractive index (n) of the medium on which the light is collected.
[0008]
NA = n × sin θ
This formula shows that it is practically impossible to make the numerical aperture (NA) higher than 1 when the focusing path is provided in air having a refractive index (n) of 1.
[0009]
In recent years, a solid immersion lens (SIL), which is an optical lens, is interposed between an objective lens and an optical disk to increase the numerical aperture (NA), and laser light is transmitted through the solid immersion lens to the optical disk. Techniques for irradiating up are proposed. For example, Terris et al., Appl. Phys. Lett. 65 (4), p388-p390, 25 July, 1994, and Terris et al., Appl. Phys. Lett, 68 (2), p141-p143, 8 January 1996, the technology is disclosed.
[0010]
In this technique, the distance between the solid immersion lens and the optical disk is shortened, and the thickness of the air layer interposed between the solid immersion lens and the optical disk is minimized. Specifically, the distance between the solid immersion lens and the optical disk is set to be equal to or less than the wavelength used for the laser light. As a result, there is no air layer optically between the solid immersion lens and the optical disc, the solid immersion lens and the optical disc are in optical contact, and the numerical aperture (NA) is 1 or more. It is possible to do. For example, it has been proposed that the distance between the solid immersion lens and the optical disc is 100 nm or less, preferably about 50 nm at the maximum.
[0011]
The solid immersion lens is mounted on, for example, a slider so that the above-described distance is maintained between the solid immersion lens and the optical disk. The slider forms an air layer by rotation of the optical disk between the slider and the solid immersion lens mounted thereon is levitated and supported on the optical disk thus rotated. For example, the slider is formed with a groove on the surface facing the optical disc, whereby the flying height of the solid immersion lens with respect to the optical disc is set to a predetermined amount.
[0012]
[Problems to be solved by the invention]
By the way, when the numerical aperture exceeds 1, unless control is performed to sufficiently reduce the thickness of the air layer, the recording accuracy or The reproduction signal deteriorates. That is, for example, as described above, unless the distance between the solid immersion lens and the optical disk is set to 100 nm or less, preferably about 50 nm, the recording accuracy and the reproduction accuracy deteriorate.
[0013]
Further, when the optical disk is driven in a state where the rotation speed is constant, the linear velocity changes as the optical disk moves in the radial direction. Therefore, when the solid immersion lens is mounted on the slider as described above and the distance between the solid immersion lens and the optical disk is held in an optical contact state, in the radial direction of the optical disk, The thickness of the air layer formed between the solid immersion lens and the optical disk is not constant. Even if the shape is optimized by providing a groove on the surface of the slider facing the optical disk, the diameter of the optical disk When moving in the direction, the flying height cannot be kept uniform.
[0014]
For example, if the normal recording laser power or erasing laser power is applied when the distance between the solid immersion lens and the optical disk is smaller than a predetermined value, the distance between the solid immersion lens and the optical disk As a result, the optical energy is transmitted to the optical disc more than necessary. If more light energy than necessary is transmitted, the area where the information signal is to be recorded or erased is projected and the heating area is widened. As a result, the information signal of the adjacent recording track is erased.
[0015]
Conversely, when the solid immersion lens and the optical disc are separated from each other by a predetermined distance, the coupling efficiency between the solid immersion lens and the optical disc can be obtained even when a normal recording laser power or an erasing laser power is applied. Therefore, the light energy is not sufficiently transmitted to the optical disk. In this case, the area where the information signal is to be recorded or erased is not sufficiently heated, and the information signal cannot be recorded or erased.
[0016]
Further, since the solid immersion lens and the optical disc as described above are closer than a predetermined distance, the reproduction power margin is narrowed not only at the time of recording or erasing the information signal, but also at the time of reproduction. This leads to a problem that the / N ratio decreases.
[0017]
The present invention has been made in view of the above-described circumstances, and even when the distance between the optical disk and the optical lens that condenses laser light on the optical disk is deviated from a predetermined value, It is an object of the present invention to provide a recording and / or reproducing apparatus and a recording and / or reproducing method capable of reliably recording, reproducing or erasing an information signal.
[0018]
[Means for Solving the Problems]
In order to solve the above-described problems, the recording and / or reproducing apparatus according to the present invention is configured such that a laser beam is incident from an incident surface, and an emission surface that emits the laser beam to the signal recording medium is optically coupled to the signal recording medium. Based on the distance information, the optical lens to be contacted, the light intensity changing means for changing the light intensity of the laser light, the distance detecting means for detecting the distance between the optical lens and the signal recording medium and outputting the distance information And a light intensity control means for controlling the light intensity changing means so that the light intensity of the laser light emitted from the emission surface and irradiated on the signal recording medium is a predetermined light intensity. A distance detection pattern provided on the recording medium runs on a distance control pattern formed as a concave groove extending in a direction perpendicular to the recording track by a light spot formed by a laser beam emitted from the emission surface. The distance information is obtained based on the return light detection unit that detects the light amount of the return light for distance detection obtained in this way, and the distance detection signal obtained according to the light amount of the return light for distance detection detected by the return light detection unit. A distance information acquisition unit to acquire.
[0019]
The recording and / or reproducing apparatus having such a configuration includes an optical lens in which a laser beam is incident from an incident surface, and an emission surface that emits the laser beam to a signal recording medium is in optical contact with the signal recording medium, and Distance information indicating the distance to the signal recording medium is emitted on a distance control pattern formed as a concave groove extending in a direction perpendicular to the recording track in the distance detection area provided on the signal recording medium. Obtained by the distance detection means based on the distance detection signal obtained according to the amount of the return light for distance detection obtained by scanning with the light spot formed by the laser light emitted from the surface, by the light intensity control means, Based on this distance information, the light intensity changing means for changing the light intensity of the laser light is controlled, and the light intensity of the laser light emitted from the emission surface and irradiated onto the signal recording medium is predetermined. To the light intensity.
[0020]
Thereby, even when the distance between the optical lens and the signal recording medium is deviated from the predetermined distance, the signal recording medium is always irradiated with laser light having a predetermined light intensity. .
[0021]
The recording and / or reproducing method according to the present invention includes a laser beam emitted from a light source that is incident from an incident surface and an output surface that emits the laser beam to a signal recording medium in order to solve the above-described problem. The formed optical lens is brought into optical contact with the signal recording medium, and the laser beam emitted from the emission surface and irradiated onto the signal recording medium based on the detection result of the distance between the optical lens and the signal recording medium Is set to a predetermined light intensity. In the recording and / or reproducing method according to the present invention, the distance between the optical lens and the signal recording medium is set within the distance detection area provided in the signal recording medium while the output of the laser beam of the light source is constant. The amount of return light for distance detection obtained by scanning the distance control pattern formed as a concave groove extending in the direction perpendicular to the recording track with the light spot formed by the laser light emitted from the emission surface. Detection is performed based on the corresponding distance detection signal.
[0022]
Thereby, even when the distance between the optical lens and the signal recording medium is deviated from the predetermined distance, the signal recording medium is always irradiated with laser light having a predetermined light intensity. .
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Since the embodiments are preferred specific examples of the present invention, various technically preferable limitations are given, but the scope of the present invention is not limited to the embodiments unless otherwise specified. It is not limited to the aspect shown by.
[0024]
In this embodiment, the recording and / or reproducing apparatus according to the present invention is applied as an optical disk apparatus that records and reproduces an information signal on a signal recording medium by condensing a laser beam with an optical pickup.
[0025]
As shown in FIG. 1, the optical pickup 10 included in the optical disc apparatus includes a light source 11, a beam splitter 12, an objective lens 13, a solid immersion lens (SIL) 14, a light detection unit 15, and a processing circuit 16. ing. The optical pickup 10 includes a slider 17 and an arm 18 as a holding means for the solid immersion lens 14.
[0026]
Further, as shown in FIG. 1, the servo control unit 19 and the light source driving unit 20 to which the output signal of the processing circuit 16 is input are components of the optical disc apparatus including the optical pickup 10.
[0027]
Here, the light source driving unit 20 functions as a light intensity changing unit that changes the light intensity of the laser light emitted from the light source 11, and the processing circuit 16 is a distance between the solid immersion lens 14 and the optical disc 100. The servo control unit 19 controls the light source driving unit 20 based on the distance information and is emitted from the emission surface 14a of the solid immersion lens 14. It functions as a light intensity control means for setting the light intensity of the laser light irradiated onto the optical disc 100 to a predetermined light intensity.
[0028]
The optical pickup 10 is provided in an optical disc apparatus, and records and reproduces information signals with respect to the optical disc 100 that is a signal recording medium. Then, the optical pickup 10 detects the distance between the solid immersion lens 14 and the optical disc 100, controls the laser power of the light source 11 according to the distance, and sets the light intensity of the laser light irradiated on the optical disc 100. It has a predetermined light intensity.
[0029]
The distance between the solid immersion lens 14 and the optical disc 100 is detected by a distance detection pattern formed by a concave groove formed in the optical disc 100 described later.
[0030]
The optical disk 100 is, for example, a magneto-optical disk on which information signals are recorded magneto-optically. The optical disc 100 is easily formed by, for example, injection molding, but is not limited thereto, and may be formed by using, for example, a glass substrate or an aluminum substrate as a substrate.
[0031]
Further, as shown in FIG. 2, the optical disk 100 has a data area D in which data is recorded. _A And data area D _A Servo area D in which servo information for the optical disc apparatus to perform tracking servo etc. is recorded in the header portion of _S And are formed. This data area D _A And servo area S _A One recording track in FIG. 1 constitutes a sector. In FIG. 2, a data area D is included in a part of the optical disc 100. _A And servo area S _A Is actually formed, but the data area D is actually included in the entire optical disc 100. _A And servo area S _A Is formed.
[0032]
Servo area S _A In this field, tracking information used for tracking servo, data address information, and the like are recorded. And servo area S _A Has a groove portion constituting a distance detection pattern. Hereinafter, the servo region S in which the concave groove portion is formed. _A The area inside is called a distance detection area.
[0033]
FIG. 3 shows a servo area S shown as details of the A part in FIG. _A The distance detection area is shown. As shown in FIGS. 3A and 3B, a plurality of concave groove portions (concave groove portions) 100a extending in a direction perpendicular to the recording track of the optical disc 100 are formed in the distance detection region. A distance detection pattern is formed. The groove depth of the recessed groove portion 100a is set to a predetermined depth. For example, the groove depth of the recessed groove portion 100a is selected to be about 1/8 of the wavelength λ of the laser light emitted from the light source 11. Each groove 100a is arranged at a predetermined pitch (spatial frequency) in the rotation direction of the optical disc 100 in the distance detection region.
[0034]
The optical pickup 10 controls the laser power of the light source 11 in accordance with a change in the amount of return light for distance detection obtained when the light spot is scanned over the distance detection region where the concave groove portion 100a is formed. Yes. The detection of the distance between the solid immersion lens 14 and the optical disc 100 based on the detection of the concave groove portion 100a will be described later.
[0035]
The light source 11 is controlled by the light source driving unit 20 to have a predetermined laser power and emits a reproduction laser beam or a recording laser beam. Further, the laser power of the light source 11 is set to a predetermined power when scanning the distance detection region with a light spot.
[0036]
The laser light emitted from the light source 11 passes through the beam splitter 12 and enters the objective lens 13. The objective lens 13 converges and emits the laser toward the solid immersion lens 14.
[0037]
The solid immersion lens 14 is formed in a substantially hemispherical shape that is convex on the incident side of the laser beam L. In the solid immersion lens 14, the spherical portion is an incident surface 14 b on which the laser light L is incident, and the flat portion is a surface that emits the laser light L incident from the incident surface 14 b toward the optical disc 100. It is set as the output surface 14a which opposes.
[0038]
The solid immersion lens 14 is disposed such that the distance between the emission surface 14a and the optical disc 100 is 200 nm or less. As a result, there is no optical air layer between the solid immersion lens 14 and the optical disc 100, and the solid immersion lens and the optical disc 100 are in optical contact with each other. The numerical aperture of the solid immersion lens 14 is 1 or more.
[0039]
The solid immersion lens 14 and the objective lens 13 described above constitute a two-group lens that focuses the laser light emitted from the light source 11 onto the optical disc 100.
[0040]
Further, the solid immersion lens 14 is mounted on the slider 17. The slider 17 floats the solid immersion lens 14 over the rotating optical disc 100 through an air layer. That is, an air layer is formed by the rotation of the optical disc 100 between the air layer forming surface 17 a of the slider 17 facing the optical disc 100 and the optical disc 100, and the solid immersion lens 14 is integrated with the slider 17. As a result, it is levitated and supported on the rotating optical disc 100.
[0041]
When the solid immersion lens 14 is thus floated on the optical disc 100, the distance between the solid immersion lens 14 and the optical disc 100, that is, the flying height is 200 nm or less, and is in optical contact with the optical disc 100. It is made to the state.
[0042]
The slider 17 is supported by an arm 18. The flying height of the slider 17 is determined by the load applied to the air layer forming surface 17a via the arm 18 and the rigidity of the air layer.
[0043]
Here, the relationship between the distance between the solid immersion lens 14 and the optical disc 100 and the laser beam emitted from the emission surface 14a of the solid immersion lens 14 will be described.
[0044]
A numerical aperture larger than 1 is realized by the objective lens 13 and the solid immersion lens 14 only when the solid immersion lens 14 and the optical disc 100 are in an optical contact state.
[0045]
For example, when the solid immersion lens 14 moves away from the optical disc 100 within the optical contact state, the ratio of laser light that is not emitted from the emission surface 14a but reflected by the emission surface 14a increases rapidly. To do. Further, when the solid immersion lens 14 moves away from the optical disc 100 beyond the range in which such optical contact is made, the laser light is reflected almost 100% (total reflection) on the emission surface 14a.
[0046]
That is, as shown in FIG. 4, when the distance (δ) between the solid immersion lens 14 and the optical disc 100 is increased in the optically contacted state, the return light reflected on the exit surface 14a is reflected. The amount of return light for detecting a distance increases. As shown in FIG. 4, between the distance (δ) between the solid immersion lens 14 and the optical disc 100 and the amount of return light for distance detection, the horizontal axis is the distance (δ), and the vertical axis When the amount of return light for distance detection is taken, there is a relationship as an upward convex function. When the solid immersion lens 14 is further moved away from the optical disc 100, the amount of distance detection return light does not increase and remains substantially constant.
[0047]
On the other hand, as shown in FIG. 4, the power of the laser beam on the optical disk 100 (board surface power) shows an opposite tendency in relation to the amount of return light for distance detection. Therefore, when the distance (δ) between the solid immersion lens 14 and the optical disc 100 is increased in a state where optical contact is made, the board power decreases.
[0048]
There is a relationship as described above between the distance between the solid immersion lens 14 and the optical disc 100 and the laser beam emitted from the emission surface 14a of the solid immersion lens 14.
[0049]
Therefore, if the distance between the solid immersion lens 14 and the optical disc 100 fluctuates, the board power fluctuates and information signals may not be recorded or reproduced on the optical disc 100 in some cases. The variation in the distance between the solid immersion lens 14 and the optical disc 100 occurs, for example, when the linear velocity is not constant in the radial direction of the optical disc 100 when a slider is used.
[0050]
For this reason, the optical pickup 10 controls the laser power of the light source 11 according to the distance between the solid immersion lens 14 and the optical disk 100, and sets the light intensity of the laser light irradiated to the optical disk 100 to a predetermined intensity. I have to.
[0051]
The detection of the distance between the solid immersion lens 14 and the optical disc 100 is acquired from the distance detection return light obtained when the light spot is scanned on the distance detection area detected by the processing circuit 16. Details will be described later.
[0052]
The laser beam converged by the objective lens 13 is condensed on the optical disc 100 through the solid immersion lens 14 that is floated on the optical disc 100 by a fixed amount by the slider 17.
[0053]
The laser light condensed by the solid immersion lens 14 and irradiated onto the optical disc 100 is incident on the beam splitter 12 through the solid immersion lens 14 and the objective lens 13 as return light reflected on the optical disc 100. . At the time of reproduction, return light reflected on the optical disc 100 (hereinafter referred to as data modulation return light) is modulated by an information signal recorded on the optical disc 100.
[0054]
The beam splitter 12 has a reflection surface, and the distance detection return light and the data modulation return light are reflected toward the light detection means 15 by the reflection surface.
[0055]
The light detection means 15 outputs a light detection signal corresponding to the return light. The light detection means 15 detects the light amount of the distance detection return light when the distance detection region is scanned by the light spot. In this case, the amount of distance detection return light detected by the light detection means 15 changes corresponding to the fact that the solid immersion lens 14 crosses the concave groove portion 100a. The light detection means 15 outputs a light detection signal to the processing circuit 16.
[0056]
The processing circuit 16 performs various signal processing on the input photodetection signal. Further, the processing circuit 16 detects a distance detection signal corresponding to the distance detection return light when the distance detection area is scanned with the light spot, and obtains distance information from the distance detection signal.
[0057]
The processing circuit 16 obtains distance information indicating the distance between the solid immersion lens 14 and the optical disc 100 from the distance detection signal as follows.
[0058]
As described above, the concave groove portion 100a is formed at a predetermined pitch in the rotation direction of the optical disc 100. When the solid immersion lens 14 crosses the concave groove portion 100a, the distance between the emitting portion where the laser light is actually emitted on the emitting surface 14a of the solid immersion lens 14 and the optical disc 100 changes at a constant period. In the solid immersion lens 14, the emission part is usually located at a substantially central portion of the emission surface 14 a.
[0059]
For example, as shown in FIG. ₁ And the distance between the optical disc 100 and the bottom surface 100a of the groove 100a. ₁ Distance to δ _A Alternatively, the bottom surface 100a of the groove 100a ₁ The distance δ to the surface that is convex with respect to the surface, that is, the surface 100b that is adjacent to the groove 100a _B And change.
[0060]
Therefore, the light amount of the return light for distance detection obtained by the light spot collected by the solid immersion lens 14 crossing the distance detection region changes according to such a change in distance, and has a constant amplitude. It is detected as a distance detection signal having. That is, the light amount of the return light for distance detection includes the refractive index of the solid immersion lens 14, the numerical aperture (NA), the configuration and refractive index of the optical disc 100, the wavelength of the laser light emitted from the light source 11, and the solid immersion lens 14. It is determined by the distance to the optical disc 100, and the like, and is one of the factors that determine the amount of return light for distance detection as described above, and the emitting portion 14a of the solid immersion lens 14 that is one of the factors. ₁ Since the distance between the optical disk 100 and the optical disc 100 changes as the groove 100a crosses, the light amount of the distance detection return light changes accordingly and is detected as a distance detection signal having a constant amplitude.
[0061]
Further, the frequency of the distance detection signal obtained in this way corresponds to the pitch and the linear velocity since the groove 100a is formed at a predetermined pitch in the distance detection region.
[0062]
The processing circuit 16 acquires a distance detection signal having a predetermined frequency corresponding to the pitch of the groove 100a in the signal obtained by scanning the solid immersion lens 14 on the optical disc 100, and the amplitude of the distance detection signal. Get distance information from. The processing circuit 16 obtains distance information based on the principle described below based on the amplitude of the distance detection signal.
[0063]
FIG. 4 shows the distance between the solid immersion lens 14 and the optical disc 100 and the amount of return light for distance detection when the solid immersion lens 14 and the optical disc 100 are in optical contact. As such, there is a certain relationship. From this, the emitting portion 14a of the solid immersion lens 14 is obtained. ₁ And the emission portion 14a of the optical disc 100. ₁ The distance δ with the portion facing the first distance δ _X In this case, the light amount of the distance detection return light is usually the first light amount R. _X And the aforementioned first distance δ _X A second distance δ different from _Y In this case, the light amount of the distance detection return light is usually the second light amount R. _Y Will be shown. For example, when the laser power in the light source 11 may change, it is not uniquely determined in this way, and such a case will be described later.
[0064]
Here, considering the case where the light spot crosses the concave groove portion 100a, the light quantity of the return light for distance detection at that time is the emission portion 14a of the solid immersion lens 14. ₁ Is changed with a certain amplitude by crossing the groove 100a. As shown in FIG. 5, the change in the light amount of the distance detection return light is as follows. ₁ The surface of the optical disc 100 facing the surface is the bottom surface 100a of the groove 100a. ₁ And the surface 100b adjacent to the concave groove portion 100a alternates. Therefore, the amplitude of the change in the amount of the return light for distance detection is the emission unit 14a. ₁ The bottom surface 100a of the groove 100a ₁ Of the return light for distance detection when the two are opposed to each other, and the emitting portion 14a ₁ The difference from the light amount of the return light for distance detection when the surface 100b provided adjacent to the concave groove portion 100a is opposed to the concave groove portion 100a is shown.
[0065]
On the other hand, the relationship existing between the distance between the solid immersion lens 14 and the optical disc 100 and the amount of return light for distance detection in the state of optical contact is expressed by the distance (δ) on the horizontal axis. When the amount of return light for distance detection is taken on the vertical axis, the relationship is shown as an upward convex function. The groove depth of the recessed groove portion 100a is constant and is known.
[0066]
For the above reasons, the emission portion 14a of the solid immersion lens 14 is detected with respect to a difference in the light amount of a certain distance detection return light. ₁ And the optical disc 100 are uniquely determined. That is, in FIG. 4, the first light quantity R of the return light for distance detection. _X Is the emitting part 14a. ₁ Is the bottom surface 100a of the groove 100a. ₁ And the second light quantity R. _Y Is the emitting part 14a. ₁ Is the bottom surface 100a of the groove 100a. ₁ Since the groove depth of the recessed groove portion 100a is constant, the first distance δ is assumed. _X And the second distance δ _Y Is specified, and the distance between the solid immersion lens 14 and the optical disc 100 is specified. If the surface 100b adjacent to the groove 100a and the surface of the optical disc 100 are at the same height, the second distance δ _Y Is the distance between the solid immersion lens 14 and the surface of the optical disc 100.
[0067]
Further, for example, the distance detected between the solid immersion lens 14 and the optical disc 100 and the relationship between the amplitude of the light amount of the return light for distance detection is stored as information such as a table or a relational expression. The distance between the solid immersion lens 14 and the optical disc 100 can be obtained directly based on the difference in the amount of detection return light.
[0068]
Further, when reproducing the distance detection region, the laser power of the laser light is set to a predetermined value. On the other hand, the laser power of the light source 11 may change, and in this case, the absolute value of the light amount of the distance detection return light changes accordingly. However, even in such a case, the difference itself in the light amount of the return light for distance detection hardly changes, so that the distance between the solid immersion lens 14 and the optical disc 100 can be specified.
[0069]
Based on the principle as described above, the distance information is calculated based on the difference in the light amount of the distance detection return light detected when the light spot crosses the concave groove 100a indicated by the amplitude of the distance detection signal. The processing circuit 16 outputs this distance information to the servo control unit 19.
[0070]
The servo control unit 19 outputs a control signal corresponding to the distance information to the light source driving unit 20, controls the light source driving unit 20, and controls the amount of driving current supplied to the light source 11.
[0071]
The light source 11 emits a laser beam as laser power corresponding to the amount of driving current supplied from the light source driving unit 20. Specifically, when the solid immersion lens 14 and the optical disc 100 are separated from each other by a predetermined distance according to the supply amount of the driving current, the laser power is increased accordingly. If the solid immersion lens 14 and the optical disc 100 are closer than a predetermined distance, the laser power is reduced accordingly.
[0072]
Thus, the laser light output from the light source 11 is controlled to a laser power corresponding to the distance between the solid immersion lens 14 and the optical disc 100 based on the distance information.
[0073]
The optical pickup 10 having the above-described configuration is configured to apply a reproduction laser beam or a recording laser beam having a predetermined laser power on the optical disc 100 by the objective lens 13 and the solid immersion lens 14 during reproduction or recording. The light is condensed and information signals are written to or read from the optical disc 100.
[0074]
In the optical pickup 10, the laser power of the light source 11 is controlled to a laser power corresponding to the distance between the solid immersion lens 14 and the optical disk 100 based on the distance information. Thereby, the light intensity of the laser light irradiated onto the optical disk 100 is set to a predetermined light intensity regardless of the distance between the solid immersion lens 14 and the optical disk 100.
[0075]
Therefore, the optical pickup 10 can focus the laser beam having the optimum light intensity on the optical disc 100 even when the linear velocity is not constant in the radial direction of the optical disc 100, thereby causing deterioration. The information signal can be recorded, reproduced, or erased from the optical disc 100 without doing so.
[0076]
For example, when acquiring distance information indicating that the solid immersion lens 14 and the optical disc 100 are closer than a predetermined distance, the servo control unit 19 supplies driving current from the light source driving unit 20 to the light source 11. The amount is controlled to reduce the laser power of the light source 11. As a result, the light intensity of the laser light applied to the optical disc 100 is reduced in accordance with the distance between the solid immersion lens 14 and the optical disc 100. Thus, the optical pickup 10 prevents the normal recording laser power or the erasing laser power from being applied even when the solid immersion lens and the optical disk are closer than a predetermined distance, for example. It is possible to prevent the information signal of the adjacent recording track from being erased.
[0077]
For example, when acquiring distance information indicating that the solid immersion lens 14 and the optical disc 100 are separated from each other by a predetermined distance, the servo control unit 19 supplies driving current from the light source driving unit 20 to the light source 11. The amount is controlled to increase the laser power of the light source 11. As a result, the light intensity of the laser light applied to the optical disc 100 is increased according to the distance between the solid immersion lens 14 and the optical disc 100. As a result, even if the solid immersion lens and the optical disc are separated from each other by a predetermined distance, the optical pickup 10 tries to perform recording or erasing because the light intensity of the laser beam is weakened by being irradiated onto the optical disc 100. It can be prevented that the information signal cannot be recorded or erased without sufficiently heating the region.
[0078]
Furthermore, since the optical pickup 10 can set the laser beam irradiated onto the optical disc 100 in accordance with the distance between the solid immersion lens 14 and the optical disc 100 to an optimum light intensity, the power margin of the laser beam can be reduced. It can also be expanded.
[0079]
Further, since the optical pickup 10 detects the distance between the solid immersion lens 14 and the optical disc 100 for each distance detection area in which the concave groove portion 100a is formed in the servo area forming the header in the sector, the optical pickup 10 is detected for each sector. It is possible to manage the laser power easily.
[0080]
In addition, distance information can also be obtained based on one groove 100a formed in the distance detection region. However, the distance information is obtained with high reliability by obtaining the distance information with reference to the light amount of the distance detection return light obtained when the light spot is scanned on the plurality of concave grooves 100a. Further, the distance detection signal obtained when the light spot is scanned over the distance detection region where the plurality of concave groove portions 100a are formed at a predetermined pitch has a frequency corresponding to the pitch and linear velocity of the concave groove portions 100a. Therefore, the processing circuit 16 can acquire a distance detection signal used for distance control by acquiring a specific frequency band.
[0081]
Further, the groove portion 100a is formed in the distance detection area of the optical disc 100 by the first pitch and the second pitch different from the first pitch, and the first and second pitches. It is also possible to obtain distance information from each distance detection signal obtained when a light spot is scanned over the distance detection region where the concave groove portion 100a is formed.
[0082]
For example, the optical pickup 10 is a distance detection signal (hereinafter referred to as a first distance detection signal) obtained by scanning a light spot on a distance detection region where the groove 100a is formed with a first pitch. Distance information cannot be obtained from the distance detection signal obtained by scanning the light spot over the distance detection area where the concave groove portion 100a is formed with the second pitch (hereinafter referred to as the second distance detection signal). Distance information can be obtained.
[0083]
Furthermore, distance information can be obtained from the first and second distance detection signals also based on the following principle.
[0084]
As described above, the optical pickup 10 obtains a distance detection signal by scanning a light spot on the distance detection region where the concave groove portion 100a is formed at a certain pitch. The relationship between the spot and the pitch of the groove 100a is that the width of the groove 100a is narrower than the spot diameter of the light spot, that is, when the pitch is short, the amplitude of the light amount change of the return light for distance detection decreases. Is established.
[0085]
On the other hand, the spot diameter of the light spot focused on the solid immersion lens 14 and formed on the optical disc 100 becomes smaller as the distance is shorter in relation to the distance between the solid immersion lens 14 and the optical disc 100.
[0086]
By changing the distance between the solid immersion lens 14 and the optical disc 100 from such a relationship, by scanning the light spot on the distance detection area where the concave groove portion 100a is formed with the first and second pitches, For example, a distance detection signal as shown in FIG. 6 can be obtained.
[0087]
6A shows the first distance detection signal, and in FIG. 6B, the groove 100a is formed with a second pitch that is longer than the first pitch. A second distance detection signal obtained by scanning a light spot on the distance detection region is shown. 6A and 6B, distance detection signals obtained at respective pitches when the distance L between the solid immersion lens 14 and the optical disc 100 is 50 nm (thin line) and 200 nm (thick line). Is shown.
[0088]
The first distance detection signal shown in (A) of FIG. 6 indicates the distance between the solid immersion lens 14 and the optical disc 100 when compared with the result of the second distance detection signal shown in (B) of FIG. As a result, the amount of change in amplitude is larger than the amount of change.
[0089]
This is because the width of the groove 100a formed by the second pitch is sufficiently larger than the spot diameter of the light spot, while the width of the groove 100a formed by the first pitch is the width of the light spot. This is because it approximates the spot diameter. That is, when a light spot is irradiated on the concave groove portion 100a formed with the first pitch, when the solid immersion lens 14 is moved toward and away from the optical disc 100, the length close to the width of the concave groove portion 100a. This is because the spot diameter of the light spot changes.
[0090]
In this way, even if the amount of change in the distance between the solid immersion lens 14 and the optical disc 100 is the same, the amount of change in the amplitude of the first distance detection signal is large, and the change in the amplitude of the second distance detection signal is large. The amount is smaller.
[0091]
Therefore, in the state in which each distance detection region where the concave groove portion 100a is formed with the first and second pitches such that the distance detection signal as shown in FIG. 6 is obtained is in optical contact. The distance information can be obtained from the amplitudes of the first and second distance detection signals obtained by scanning the light spot. For example, the amplitude of the first distance detection signal and the amplitude of the second distance detection signal can be compared, and distance information can be obtained from the difference.
[0092]
Specifically, when the difference between the amplitude of the first distance detection signal and the amplitude of the second distance detection signal is large, the solid immersion lens 14 and the optical disc 100 are more in an optical contact state. If the difference between the amplitude of the first distance detection signal and the amplitude of the second distance detection signal is small, the solid immersion lens 14 and the optical disc 100 are in optical contact. In this state, it can be seen that the state is closer to each other. Therefore, the distance between the solid immersion lens 14 and the optical disc 100 is specifically derived from such a relationship.
[0093]
In this case, the distance detection signal obtained by scanning the light spot on the distance detection region where the concave groove portion 100a is formed by each pitch is determined by the frequency corresponding to the first and second pitches. Do.
[0094]
The optical pickup 10 acquires distance information from the amplitudes of the first and second distance detection signals obtained by scanning the light spot on the distance detection region formed by the concave grooves 100a having different pitches. By doing so, even when the laser power of the light source 11 fluctuates while scanning the distance detection region, such fluctuation amount is canceled and the fluctuation of the laser power is affected. Accordingly, the distance between the solid immersion lens 14 and the optical disc 100 can be accurately grasped.
[0095]
Further, for example, the difference between the distance between the solid immersion lens 14 and the optical disc 100 and the amplitude of the first and second distance detection signals (or the amplitude of the light amounts of the first and second distance detection return lights) and Is stored as information such as a table or a relational expression is obtained, so that the difference between the amplitudes of the detected first and second distance detection signals or the first and second distance detection signals can be detected. The distance information can be obtained directly from the difference in the amount of return light.
[0096]
Further, in the above-described embodiment, the light intensity changing means is configured as the light source driving unit 20, but is not limited thereto. FIG. 7 shows an optical pickup 10 provided with light intensity changing means having another configuration.
[0097]
As shown in FIG. 7, the optical pickup 10 has an acousto-optic converter (AO modulator) 21 disposed on the optical path of the laser light emitted from the light source 11 as light intensity detection means.
[0098]
The optical pickup 10 shown in FIG. 7 is configured in substantially the same manner as the optical pickup 10 shown in FIG. 1, but differs in that an acousto-optic converter 21 is provided instead of the light source driving unit 20. The same components as those of the optical pickup 10 shown in FIG. 1 are denoted by the same reference numerals in FIG.
[0099]
The acousto-optic converter 21 is an optical member that changes the amount of transmitted light. Specifically, the acousto-optic converter 21 changes the amount of transmitted light by converting optical energy into acoustic energy. The acousto-optic converter 21 is on the optical path of the laser light emitted from the light source 11 and is disposed between the light source 11 and the beam splitter 12, for example.
[0100]
The servo control unit 19 that controls the acousto-optic converter 21 outputs a control signal corresponding to the distance information to the acousto-optic converter 21 to change the amount of transmitted light in the acousto-optic converter 21.
[0101]
As a result, the amount of transmitted laser light emitted from the light source 11 is changed in the acousto-optic converter 21 controlled according to the distance information detected by the processing circuit 16, and the beam splitter 12 and the objective lens 13 are changed. , And the solid immersion lens 14, the light is condensed on the optical disc 100.
[0102]
Therefore, since the laser light applied to the optical disk 100 is controlled based on the distance information in the acousto-optic converter 21, it corresponds to the distance between the solid immersion lens 14 and the optical disk 100, and the optimum light. It is assumed to be strength.
[0103]
As a result, the optical pickup 10 can concentrate laser light with a predetermined light intensity on the optical disc 100 even when the linear velocity in the radial direction of the optical disc 100 is not constant, and deteriorates. The information signal can be recorded on, reproduced from, or deleted from the optical disc 100.
[0104]
For example, when acquiring distance information indicating that the solid immersion lens 14 and the optical disc 100 are closer than a predetermined distance, the servo control unit 19 reduces the amount of transmitted light in the acousto-optic converter 21. Thus, the acousto-optic converter 21 is controlled. As a result, the light intensity of the laser light applied to the optical disc 100 is reduced according to the distance between the solid immersion lens 14 and the optical disc 100.
[0105]
Further, in the above-described embodiment, the distance detection means is performed based on the light amount of the distance detection return light when the light spot is scanned on the concave groove portion 100a formed on the optical disc 100. However, the distance detection means is not limited to this. FIG. 8 shows an optical pickup 10 having a distance detecting means having another configuration.
[0106]
As shown in FIG. 8, the optical pickup 10 includes a charging unit 22 and a distance detection unit 23 as distance detection means.
[0107]
The optical pickup 10 shown in FIG. 8 is configured in substantially the same manner as the optical pickup 10 shown in FIG. 1, but instead of acquiring distance information from a distance detection signal detected by the processing circuit 16, a charging unit 22 and the distance detector 23 are different in that distance information is acquired. The same components as those of the optical pickup 10 shown in FIG. 1 are denoted by the same reference numerals in FIG.
[0108]
The charging unit 22 is a portion that is formed on the emission surface 14a of the solid immersion lens 14 by a conductive material, and forms a capacitance from the conductive material formed on the optical disc 100. The distance detection unit 23 is a static detection unit. It has a capacitance detection function for detecting capacitance and a distance information acquisition function for acquiring distance information from the capacitance detected by the capacitance detection function.
[0109]
The distance detecting means configured as described above forms the control of the light intensity of the laser light irradiated on the optical disc 100 in the charging portion 22 and the portion formed by the conductive material of the optical disc 100 (hereinafter, optical disc side charging portion) 101. The distance information obtained based on the measured capacitance is used.
[0110]
The charging unit 22 is formed as a thin film integrally from the emission surface 14 a of the solid immersion lens 14 to the air layer formation surface 17 a of the slider 17. The charging unit 22 is made of aluminum, for example. Also,
The optical disk side charging unit 101 in the optical disk 100 is a part formed as a recording film or a reflection film in the optical disk 100, for example. The recording film is formed of, for example, TbFeCo in the optical disc 100. Further, the reflective film is formed of, for example, aluminum in the optical disc 100.
[0111]
As described above, the distance detection unit 23 has a capacitance detection function that detects a capacitance, and a distance information acquisition function that acquires distance information from the capacitance detected by the capacitance detection function. Yes. The distance detection unit 23 may be configured as a part of the optical pickup 10 as in the present example, or may be configured as a part of an optical disc apparatus including the optical pickup 10.
[0112]
The distance detection unit 23 can detect the capacitance formed by the charging unit 22 and the optical disc side charging unit 101 and can obtain distance information from the value of the capacitance. Then, the distance detector 23 outputs distance information obtained from the capacitance value to the servo controller 19.
[0113]
Specifically, the distance detection unit 23 acquires distance information as follows based on the capacitance value.
[0114]
The capacitance value (C) is defined as S being the surface area of the charging unit 22 and the optical disk side charging unit 101 facing each other, and more specifically, the distance between the solid immersion lens 14 and the optical disk 100, more specifically, charging. When the distance between the unit 22 and the optical disc side charging unit 101 is h, it is expressed by the equation (1).
[0115]
C = ε ₀ ・ Ε _r ・ S / h (1)
Where ε ₀ Is the vacuum dielectric constant (8.854 × 10 ^-2 (F / m)), ε _r Is the relative dielectric constant (approximately 1 in air).
[0116]
From this equation (1), it can be seen that a change in the distance between the solid immersion lens 14 and the optical disc 100 changes the capacitance value C.
[0117]
A voltage signal indicating the capacitance value C is supplied to a VOC (voltage controlled oscillator) (not shown). Here, the VOC constitutes a part of the distance detection unit 23. The VOC is composed of, for example, an LC oscillator, and outputs a signal having an oscillation frequency f shown in the equation (2) based on the capacitance value C indicated by the voltage signal and a constant inductance L inside the VOC.
[0118]
f = 1 / 2π (LC) ^1/2 ... (2)
Therefore, the oscillation frequency f can be obtained by the equation (2) from the inductance L inside the VOC and the capacitance value C obtained by the equation (1).
[0119]
The VOC output signal is supplied to a PLL (Phase Locked Loop) as a frequency phase comparator (not shown) together with a reference frequency signal output from a VCXO (voltage controlled oscillator) (not shown). Here, the VCXO and the PLL also constitute a part of the distance detection unit 23.
[0120]
The PLL compares the frequency and phase of the output signal of the VCO with the frequency and phase of the output signal of the VCXO, and outputs a signal corresponding to the error in both frequency and phase. The PLL output signal is phase compensated by a phase compensation circuit, amplified by an amplifier (not shown), and output to the servo controller 19 as distance information. Here, the phase compensation circuit and the amplifier also constitute a part of the distance detector 23.
[0121]
Specifically, the distance detection unit 23 acquires distance information based on the capacitance value with the above-described configuration.
[0122]
Thus, the distance information acquired in the distance detection unit 23 is output to the servo control unit 19, and the servo control unit 19 outputs a control signal corresponding to the distance information in the same manner as the optical pickup 10 shown in FIG. It outputs to the light source drive part 20, and the laser power of the light source 11 is controlled.
[0123]
Therefore, the optical pickup 10 can detect the distance information from the capacitance value by the distance detector 23 and control the laser power of the light source 11 based on the distance information. Thereby, the light intensity of the laser light irradiated onto the optical disk 100 is set to a predetermined light intensity regardless of the distance between the solid immersion lens 14 and the optical disk 100.
[0124]
Further, the optical pickup 10 is limited to obtaining distance information in a predetermined region, such as obtaining distance information by scanning a light spot on the groove 100a formed in the optical disc 100 as described above. In other words, distance information can be obtained over the entire circumference of the optical disc 100, so that a more optimal light intensity can be selected.
[0125]
In the above-described embodiment, the operation of the solid immersion lens 14 is performed by floating on the optical disc 100 by the slider 17, but the operating means for operating the solid immersion lens 14 is configured in this way. There is no limit. 9 and 10 show an optical pickup 10 including an actuator 30 as an operation unit for the solid immersion lens 14 having another configuration.
[0126]
As shown in FIG. 9, the optical pickup 10 operates the light spot on the concave groove portion 100a shown in FIG. 1, and acquires distance information based on the amount of return light for distance detection obtained at that time. In this configuration, an actuator 30 is provided as an operation means for the solid immersion lens 14 instead of the slider. The optical pickup 10 shown in FIG. 9 is configured in substantially the same manner as the optical pickup 10 shown in FIG. 1, and the same components as those of the optical pickup 10 shown in FIG. In addition, explanation is omitted.
[0127]
Further, as shown in FIG. 10, the optical pickup 10 forms a charging portion on the emission surface 14a of the solid immersion lens 14 shown in FIG. 8, and acquires distance information based on the capacitance value. In the configuration, an actuator 30 is provided as an operation means of the solid immersion lens 14 instead of the slider. The optical pickup 10 shown in FIG. 10 is configured in substantially the same manner as the optical pickup 10 shown in FIG. 8, and the same components as those in the optical pickup 10 shown in FIG. In addition, explanation is omitted.
[0128]
First, the actuator 30 serving as a common component in the optical pickup 10 shown in FIGS. 9 and 10 will be described.
[0129]
The actuator 30 is mounted with the solid immersion lens 14 and is supplied with a driving current to move the solid immersion lens 14 in a direction in which the solid immersion lens 14 comes in contact with and separates from the optical disc 100. The actuator 30 includes a holding part 31 and a coil winding part 32 for the solid immersion lens 14.
[0130]
The holding portion 31 is formed in a substantially flat plate shape, and an outer peripheral portion on the opposite surface side of the solid immersion lens 14 is fitted into a lens mounting opening formed near the center.
[0131]
The coil winding part 32 is formed in a substantially cylindrical shape, and the holding part 31 is formed inside. A coil is wound around the coil winding portion 32 so as to be positioned around the optical axis of the solid immersion lens 14. The actuator 30 has a magnet disposed on the outer periphery of the coil winding portion 32.
[0132]
In the actuator 30 configured in this manner, a driving current is supplied to the coil by an actuator driver (not shown), and the solid immersion lens 14 is displaced in a direction in which the solid immersion lens 14 is in contact with or separated from the optical disc 100. The focus servo can be performed by the displacement of the solid immersion lens 14 by the actuator 30.
[0133]
In the optical pickup 10 shown in FIG. 10, the charging unit 22 is formed on the emission surface 14a of the solid immersion lens 14 as described below.
[0134]
The solid immersion lens 14 has a projection 14c that is convex with respect to the emission surface 14a at the center of the emission surface 14a. The protrusion 14 c is a portion from which the laser light incident on the solid immersion lens 14 is emitted, and has an optimum shape and designed so that a desired light spot is formed on the optical disc 100.
[0135]
Further, in the solid immersion lens 14 having such a shape, a charging portion 22 made of a conductive material is formed on the emission surface 14a so as to be located on the outer periphery of the projection portion 14c. That is, the charging part 22 is formed in a substantially annular shape, is located on the outer periphery of the protrusion part 14c, and is formed on the emission surface 14a.
[0136]
Note that the shape of the charging portion 22 is not limited to being formed in a substantially annular shape as described above. For example, by using an optically transparent material for the charging unit 22, the charging unit 22 may be formed on the surface of the protrusion 14 c that faces the optical disc 100.
[0137]
As described above, in the optical pickup 10 shown in FIGS. 9 and 10, the solid immersion lens 14 is held in contact with and separated from the optical disc 100 by the actuator 30.
[0138]
The optical pickup 10 shown in FIG. 9 condenses the laser beam by the solid immersion lens 14 held by the actuator 30 and scans the light spot on the distance detection region where the concave groove portion 100a of the optical disc 100 is formed. The light detection means 15 receives the amount of distance detection return light obtained in this way. Then, the optical pickup 10 acquires distance information from the amplitude of the distance detection signal obtained in accordance with the change in the amount of the return light for distance detection in the processing circuit 16 and uses FIG. 1 based on this distance information. As in the case described, the laser power of the light source 11 is controlled.
[0139]
As a result, the optical pickup 10 shown in FIG. 9 can focus the laser light on the optical disc 100 with the optimum light intensity according to the distance between the solid immersion lens 14 and the optical disc 100.
[0140]
In the case of the optical pickup 10 shown in FIG. 10, the capacitance value formed by the charging unit 22 formed on the emission surface 14 a of the solid immersion lens 14 and the optical disc side charging unit 101 formed on the optical disc 100 is the same. It is detected by the distance detector 23. The distance detection unit 23 acquires distance information based on the capacitance value.
[0141]
The optical pickup 10 controls the laser power of the light source 11 based on the distance information, as in the case described with reference to FIG.
[0142]
Accordingly, the optical pickup 10 shown in FIG. 10 can condense the light intensity of the laser light on the optical disc 100 with the optimum light intensity according to the distance between the solid immersion lens 14 and the optical disc 100.
[0143]
Further, the optical pickup 10 shown in FIGS. 9 and 10 allows the solid immersion lens 14 to be moved in the focus direction by the actuator 30 and enables focus servo by the solid immersion lens 14. Since the optical pickup 10 controls the light intensity applied to the optical disk 100 by changing the laser power of the light source 11, the focus 30 is not left behind by the actuator 30 and the focus servo is accurately performed. Can do.
[0144]
That is, since the focus servo can be said to be control for making the laser light on the optical disc 100 have a predetermined light intensity, the optical pickup 10 is capable of lasering the light source 11 in a high frequency band that cannot be focused by the operation of the actuator 30. The light intensity can be controlled by controlling the power, and thereby focus servo can be performed with high accuracy.
[0145]
Further, the optical pickup 10 shown in FIGS. 9 and 10 is configured such that the laser power of the light source 11 is controlled so that the light intensity of the laser light irradiated onto the optical disk 100 becomes a predetermined light intensity. The present invention is not limited to such a configuration. The optical pickup 10 shown in FIGS. 9 and 10 may include the acousto-optic converter 21 described with reference to FIG. 7 instead of the light source driving unit 20 that controls the laser power of the light source 11 as light source changing means. . Even when the optical pickup 10 is configured as described above, the same effect as described above can be obtained.
[0146]
Next, a specific configuration of the optical disc apparatus including the optical pickup 10 will be described.
[0147]
The optical disk apparatus is configured to magnetically record information signals on the magneto-optical disk. Specifically, as shown in FIG. 11, the optical pickup 10, spindle motor 41, magnetic head 42, head A driving unit 43, a RAM (Random Access Memory) 44, a signal processing unit 45, an interface 46, a servo control unit 19, a light source driving unit 20, a distance detection unit 23, a feed motor 47, and a system controller 48 are provided. This optical disk apparatus is an example configured by applying the optical pickup 10 shown in FIGS. 8 and 10, and includes a charging unit 22 formed on the solid immersion lens 14 and an optical disk side charging unit 101 of the optical disk 100. The distance detector 23 is configured to detect distance information from the formed capacitance value. However, the optical disc apparatus is not limited to being configured to detect the distance information from the capacitance value by the distance detecting unit 23 as described above. For example, the optical disc apparatus is illustrated in FIGS. 1 and 9. An optical pickup 10 may be provided so that distance information can be obtained from a concave groove 100a formed in the optical disc 100.
[0148]
The spindle motor 41 is a drive unit that rotates the optical disc 100. The spindle motor 41 is driven and controlled by the system controller 48 and the servo control unit 19 and is rotated at a predetermined rotational speed. Laser light is irradiated from the optical pickup 10 to the optical disk 100 that is rotated by the spindle motor 41.
[0149]
The optical pickup 10 irradiates the optical disk 100 rotated by the spindle motor 41 with a laser beam, and reads an information signal from the optical disk 100 based on the return light (data modulation return light). The optical pickup 10 is supported so as to be movable in the vertical direction with respect to the recording track of the optical disc 100, and is driven by a feed motor 47.
[0150]
The drive of the magnetic head 42 is controlled by the head drive unit 43 to apply a magnetic field to the optical disc 100. In the optical disc 100, when a magnetic field is applied by the magnetic head 42, an information signal is written on the signal recording layer of the laser irradiation portion by the optical pickup 10. The head drive unit 43 controls the magnetic field modulation of the magnetic head 42 according to the information signal.
[0151]
The signal processing unit 45 is configured to perform various signal processing. Specifically, the signal processing unit 45 includes a signal demodulator and an error correction circuit as an information signal reproduction system, and a signal modulator and the like as an information signal recording system. The RAM 44 is a storage means for storing data, and is used as a working memory for the signal processing unit 45, for example.
[0152]
During reproduction, the signal processing unit 45 demodulates the signal read from the optical disc 100 by the optical pickup 10 using a signal demodulator, and performs error correction using a correction circuit.
[0153]
On the other hand, the signal processing unit 45 modulates data by a signal modulator and outputs the data to the head driving unit 43 during recording. The head drive unit 43 controls the drive of the magnetic head 42 as described above based on the modulation signal obtained by modulating the data.
[0154]
The interface 46 transmits / receives data to / from an externally connected electronic device. The externally connected electronic device is, for example, an external computer.
[0155]
For example, when a reproducing operation is performed in the optical disc apparatus, a reproduced signal subjected to signal processing in a signal demodulator, an error correction circuit, or the like of the signal processing unit 45 is sent to an external computer via the interface 46.
[0156]
The servo control unit 19 servo-controls lens driving means such as a biaxial actuator that holds the second group lens in the optical pickup 10 in the focusing direction and the tracking direction. Here, the second group lens includes the objective lens 13 and the solid immersion lens 14 as described above.
[0157]
The servo control unit 19 performs servo control for the feed motor 47 that feeds the optical pickup 10. Further, the servo control unit 19 performs servo control on the spindle motor 41 that rotates the optical disc 100. The servo control unit 19 performs servo control of each unit described above based on a control signal from the system controller 48.
[0158]
Further, the servo control unit 19 controls the light source driving unit 20 according to the distance information based on the capacitance value output from the optical pickup 10 acquired by the distance detection unit 23.
[0159]
The system controller 48 controls each part constituting the optical disc apparatus. As described above, the system controller 48 has a function of outputting a control signal to the servo control unit 19 to control driving of each driving unit as described above.
[0160]
In the optical disk apparatus configured as described above, with respect to the operation of reproducing the information signal from the optical disk 100, the signal of the signal processing unit 45 with respect to the signal read by the optical pickup 10 from the optical disk 100 rotated by the spindle motor 41. The demodulator demodulates the signal and the correction circuit corrects the error. Then, the reproduction signal subjected to such signal processing is sent to an externally connected electronic device via the interface 46, for example.
[0161]
As for the operation of recording the information signal on the optical disc 100, the optical disc apparatus irradiates the optical disc 100 rotated by the spindle motor 41 with a recording laser beam having a predetermined output from the optical pickup 10, and also outputs a signal. The magnetic head 42 is driven by the head driving unit 43 based on the modulation signal obtained by modulating the information signal by the signal modulator of the processing unit 45. By the magnetic field modulation of the magnetic head 42, the magnetization direction of the recording layer of the optical disc 100 is changed, and an information signal is recorded.
[0162]
Since the optical disc apparatus can set the laser power of the light source 11 in the optical pickup 10 to a laser power corresponding to the distance between the solid immersion lens 14 and the optical disc 100, the optimum optical intensity is applied on the optical disc 100. Laser light can be condensed.
[0163]
Therefore, the optical disk apparatus can obtain the same effect as that obtained by the optical pickup 10 described above. That is, for example, the optical disc apparatus can focus laser light having an optimal light intensity on the optical disc 100 even when the linear velocity is not constant in the radial direction of the optical disc 100. Information signals can be recorded on, reproduced from, or deleted from the optical disc 100 without deterioration.
[0164]
In the above-described embodiment, the optical pickup and the optical disk apparatus that record and / or reproduce information signals with respect to the magneto-optical disk have been described. However, the present invention is not limited to this, and can be applied to other optical recording media. For example, the present invention can also be applied to an optical pickup and an optical disc apparatus that perform recording and / or reproduction of an information signal with respect to another optical disc employing the near-field optical recording technology, for example, a phase change optical disc.
[0165]
In the above-described embodiment, the groove depth of the recessed groove portion 100a is set to about 1/8 of the wavelength λ of the laser light emitted from the light source 11. However, the present invention is not limited to this, and the groove depth of the recessed groove portion 100a may be other depth.
[0166]
【The invention's effect】
The recording and / or reproducing apparatus according to the present invention includes an optical lens in which a laser beam is incident from an incident surface and an emission surface for emitting the laser beam to a signal recording medium is optically contacted with the signal recording medium, and the laser beam Light intensity changing means for changing the light intensity, distance detecting means for detecting the distance between the optical lens and the signal recording medium and outputting distance information, and controlling the light intensity changing means based on the distance information. And a light intensity control means for setting the light intensity of the laser light emitted from the emission surface and irradiated onto the signal recording medium to a predetermined light intensity, so that the laser light is incident from the incident surface, and the laser light is Distance information indicating the distance between the optical recording lens whose exit surface is optically contacted with the signal recording medium and the signal recording medium is acquired by the distance detection means, and the light intensity control means Distance It may control the light intensity changing means for changing the light intensity of the laser light to a predetermined light intensity the light intensity of the laser beam irradiated on the emitted signal recording medium from the exit surface on the basis of.
[0167]
Thus, the recording and / or reproducing apparatus always has a predetermined light intensity on the signal recording medium even when the distance between the optical lens and the signal recording medium is deviated from the predetermined distance. The laser beam thus collected can be collected.
[0168]
The recording and / or reproducing method according to the present invention also includes an optical lens having an emission surface on which laser light emitted from a light source is incident from an incident surface and emits the laser light to a signal recording medium. The optical intensity of the laser light that is optically brought into contact with the medium and is emitted from the emission surface and irradiated onto the signal recording medium based on the detection result of the distance between the optical lens and the signal recording medium is set to a predetermined light intensity. As a result, even when the distance between the optical lens and the signal recording medium is deviated from the predetermined distance, the laser light having a predetermined light intensity is always focused on the signal recording medium. can do.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an optical pickup provided in an optical disc apparatus according to an embodiment of the present invention.
FIG. 2 is a plan view showing an optical disc in which a data area and a servo area are formed.
FIG. 3 is a diagram showing a distance detection area which is a partial area of the servo area described above and has a predetermined pitch and a groove.
FIG. 4 is a characteristic diagram showing the relationship between the distance between the solid immersion lens and the optical disc and the amount of return light for distance detection.
FIG. 5 is a front view showing a positional relationship between a solid immersion lens and a concave groove formed in a distance detection region provided on an optical disc.
FIG. 6 shows first and second distance detection signals obtained by scanning a light spot on a distance detection region in which concave grooves are formed at the first and second pitches; FIG. 10 is a characteristic diagram showing changes in a reproduction signal when the distance between the immersion lens and the optical disc is 50 nm and 200 nm.
FIG. 7 is a block diagram showing a configuration of an optical pickup including an acousto-optic converter as light intensity changing means.
FIG. 8 is a block diagram showing a configuration of an optical pickup that obtains distance information based on a capacitance detected from a charging unit on a surface of a solid immersion lens and a slider that faces an optical disk and an optical disk side charging unit of the optical disk. is there.
9 is a block diagram showing a configuration of an optical pickup which is a modification of the optical pickup shown in FIG. 1 and includes an actuator as an operation means of a solid immersion lens.
10 is a block diagram showing a configuration of an optical pickup which is a modification of the optical pickup shown in FIG. 8 and includes an actuator as an operation means of a solid immersion lens.
FIG. 11 is a block diagram showing a configuration of an optical disc apparatus according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Light source, 14 Solid immersion lens, 16 Processing circuit, 19 Servo control part, 20 Light source drive part

Claims (18)

In a recording and / or reproducing apparatus for condensing a laser beam on a signal recording medium and recording and / or reproducing an information signal with respect to the signal recording medium,
A light source that emits the laser light;
An optical lens in which the laser beam is incident from an incident surface, and an emission surface for emitting the laser beam to the signal recording medium is in optical contact with the signal recording medium;
A light intensity changing means for changing the light intensity of the laser beam;
Distance detecting means for detecting a distance between the optical lens and the signal recording medium and outputting distance information;
Light intensity control means for controlling the light intensity changing means based on the distance information so that the light intensity of the laser light emitted from the emission surface and irradiated on the signal recording medium is set to a predetermined light intensity; With
The distance detection means is a distance control pattern formed as a concave groove extending in a direction perpendicular to a recording track in a distance detection area provided in the signal recording medium, and the distance detection means is emitted from the emission surface. a return light detecting unit for detecting the amount of the resulting distance detecting return light is scanned by a light spot formed by the laser beam, in accordance with the amount of the return light detection unit the distance detecting return light detected by A recording and / or reproducing apparatus comprising: a distance information acquisition unit that acquires the distance information based on a distance detection signal obtained . The light source emits a laser beam having a laser power corresponding to the supplied driving current,
The light intensity changing means is a light source driving means for supplying the driving current to the light source,
The light intensity control means controls the light source driving means to change the supply amount of the driving current so that the light intensity of the laser light irradiated onto the signal recording medium is set to a predetermined light intensity. Item 4. The recording and / or reproducing apparatus according to Item 1. The light intensity changing means is an optical member that is disposed on the optical path of the laser light and changes the amount of transmitted light.
The light intensity control means controls the optical member to change the amount of the transmitted light so that the light intensity of the laser light irradiated onto the signal recording medium is a predetermined light intensity. Recording and / or playback device. The distance information acquisition unit, the recording and / or reproducing apparatus according to claim 1, wherein for acquiring the distance information from the amplitude of the distance detection signal showing a variation of an amount of the distance detecting return light. As the signal recording medium, in the distance detecting area, recording and / or reproducing apparatus according to claim 1, wherein the use of a plurality of the recessed groove portion is a predetermined pitch it is arranged. As the signal recording medium, a first distance detection region in which the concave groove portions are arranged at a first pitch, and a concave pitch portion is arranged at a second pitch that is different from the first pitch. Using the distance detection area formed by the second distance detection area,
The distance information acquisition unit includes an amplitude of a first distance detection signal indicating a change in a light amount of the first distance detection return light obtained by scanning the first distance detection region with the light spot, and The distance information is acquired from the comparison result with the amplitude of the second distance detection signal indicating the change in the amount of the second distance detection return light obtained by scanning the second distance detection region with the light spot. The recording and / or reproducing apparatus according to claim 1.   The distance detecting means includes a charging unit that is formed on the emission surface with a conductive material and forms a capacitance with the conductive unit formed on the signal recording medium, and an electrostatic that detects the capacitance. The recording and / or reproducing apparatus according to claim 1, further comprising: a capacitance detection unit; and a distance information acquisition unit that acquires the distance information from the capacitance detected by the capacitance detection unit.   The optical lens is formed in a substantially hemispherical shape convex toward the incident side of the laser light, the spherical surface is the incident surface of the laser light, and the flat surface is opposed to the signal recording medium. The recording and / or reproducing apparatus according to claim 1.   The recording and / or reproducing apparatus according to claim 1, wherein the numerical aperture of the optical lens is 1 or more. In a recording and / or reproducing method for condensing a laser beam on a signal recording medium and recording and / or reproducing an information signal on the signal recording medium,
A laser beam emitted from a light source is incident from an incident surface, and an optical lens on which an emission surface for emitting the laser beam to the signal recording medium is optically contacted with the signal recording medium, and the laser of the light source With the light output constant, the light is emitted from the emission surface on the distance control pattern formed as a concave groove extending in the direction perpendicular to the recording track in the distance detection area provided on the signal recording medium. Further, the distance between the optical lens and the signal recording medium is detected based on a distance detection signal corresponding to the amount of return light for distance detection obtained by scanning with a light spot formed by the laser beam, Based on the detection result, the light intensity of the laser light emitted from the emission surface is controlled, and the recording intensity and the light intensity of the laser light irradiated onto the signal recording medium are set to a predetermined light intensity. / Or reproduction method. The laser power corresponding to the supplied drive current is controlled to control the supply amount of the drive current to the light source that emits the laser light, and the laser light irradiated onto the signal recording medium The recording and / or reproducing method according to claim 10, wherein the light intensity is set to a predetermined light intensity.   The optical member disposed on the optical path of the laser light and changing the light amount of the transmitted light is controlled to change the light amount of the transmitted light, and the light intensity of the laser light irradiated on the signal recording medium is changed. 11. The recording and / or reproducing method according to claim 10, wherein a predetermined light intensity is obtained.   11. The recording and / or reproducing method according to claim 10, wherein the distance between the optical lens and the signal recording medium is detected from the amplitude of the distance detection signal indicating the amount of change in the amount of return light for distance detection.   11. The recording and / or reproducing method according to claim 10, wherein the signal recording medium uses a plurality of concave grooves arranged at a predetermined pitch in the distance detection area. As the signal recording medium, a first distance detection region in which the concave groove portions are arranged at a first pitch, and a concave pitch portion is arranged at a second pitch that is different from the first pitch. Using the distance detection area formed by the second distance detection area,
The amplitude of the first distance detection signal indicating the change in the amount of the first distance detection return light obtained by scanning the first distance detection area with the light spot, and the second distance detection area. Between the optical lens and the signal recording medium based on the comparison result with the amplitude of the second distance detection signal indicating the change in the amount of the second distance detection return light obtained by scanning the light spot with the light spot. The recording and / or reproducing method according to claim 10, wherein the distance is detected. A charged portion is formed of a conductive material on the emission surface,
11. The recording and / or recording according to claim 10, wherein a distance between the optical lens and the signal recording medium is detected from an electrostatic capacity formed by the charging unit and a conductive part formed on the signal recording medium. Or reproduction method.   The optical lens is formed in a substantially hemispherical shape convex toward the laser beam incident side, the spherical surface is the incident surface of the laser light, and the flat surface is opposed to the signal recording medium. The recording and / or reproducing method according to claim 10, wherein the method described above is used.   11. The recording and / or reproducing method according to claim 10, wherein an optical lens having a numerical aperture of 1 or more is used as the optical lens.

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