JP2011198424A - Optical drive device and method of correcting shift of spot - Google Patents

Abstract

A first light for performing recording on an optical disk recording medium having a bulk layer and a reference surface in which a position guide is formed in a spiral shape or a concentric shape, and the position guide. In the optical drive device that irradiates the second light for performing the position control based on the child through the common objective lens, the spot positions of the first and second lights generated due to skew and the objective lens shift Correct the displacement with higher accuracy.
A reference track TR-b1 is formed in a position in the bulk layer 5 at the same radial position as a predetermined track on a reference surface Ref. Then, using the reference track, the correction amount of the optical axis by the optical axis adjustment unit 14B is sampled for each rotation angle in a state where the spot positions of the first light and the second light are matched in the tracking direction. At the time of recording, the sampled correction amount is instructed to the optical axis adjusting unit 14B for each rotation angle to correct the spot position deviation.
[Selection] Figure 5

Description

  The present invention relates to an optical drive apparatus that performs at least recording on an optical disk recording medium and a spot position deviation correction method thereof, and in particular, is formed on a first light for performing mark recording and the optical disk recording medium. The present invention is suitable for application to an optical drive device configured to irradiate the second light for performing position control based on the position guide through a common objective lens.

JP 2008-135144 A JP 2008-176902 A JP 2009-9635 A

  As optical recording media on which signals are recorded / reproduced by light irradiation, so-called optical disks such as CD (Compact Disc), DVD (Digital Versatile Disc), and BD (Blu-ray Disc: registered trademark) are widely used. .

  Regarding the optical recording media that should be the next generation of optical recording media that are currently popular such as CDs, DVDs, and BDs, the present applicant has previously referred to the so-called Patent Document 1 and Patent Document 2 as described above. A bulk recording type optical recording medium has been proposed.

  Here, the bulk recording refers to an optical recording medium (bulk type recording medium 100) having at least a cover layer 101 and a bulk layer (recording layer) 102 as shown in FIG. This is a technique for increasing the recording capacity by performing multi-layer recording in the bulk layer 102 by irradiating laser light.

Regarding such bulk recording, the above-mentioned Patent Document 1 discloses a recording technique called a so-called micro-hologram method.
As shown in FIG. 13, the micro hologram method is roughly classified into a positive micro hologram method and a negative micro hologram method.
In the micro-hologram method, a so-called hologram recording material is used as a recording material for the bulk layer 102. As a hologram recording material, for example, a photopolymerization type photopolymer or the like is widely known.

  In the positive micro-hologram method, as shown in FIG. 13A, two opposing light beams (light beam A and light beam B) are condensed at the same position to form a fine interference fringe (hologram). This is a technique for making a recording mark.

  The negative micro-hologram method shown in FIG. 13B is the opposite of the positive micro-hologram method, and the previously formed interference fringes are erased by laser light irradiation, and the erased portion is recorded. This is a method of marking.

FIG. 14 is a diagram for explaining the negative micro-hologram method.
In the negative type micro-hologram method, an initialization process for forming interference fringes on the bulk layer 102 is performed in advance as shown in FIG. Specifically, as shown in the figure, parallel light beams C and D are irradiated so as to face each other, and their interference fringes are formed on the entire bulk layer 102.
In this way, after interference fringes are formed in advance by the initialization process, information recording is performed by forming erase marks as shown in FIG. Specifically, information recording with an erasure mark is performed by irradiating a laser beam in accordance with recording information in a state in which an arbitrary layer position is focused.

The present applicant has also proposed a recording method for forming a void (hole) as a recording mark as disclosed in Patent Document 2, for example, as a bulk recording method different from the micro-hologram method.
In the void recording method, for example, a laser beam is irradiated at a relatively high power to the bulk layer 102 made of a recording material such as a photopolymerization type photopolymer, and voids are recorded in the bulk layer 102. It is a technique to do. As described in Patent Document 2, the hole portion formed in this manner is a portion having a refractive index different from that of the other portion in the bulk layer 102, and the light reflectance is increased at the boundary portion. become. Therefore, the hole portion functions as a recording mark, thereby realizing information recording by forming the hole mark.

Since such a void recording method does not form a hologram, it is only necessary to perform light irradiation from one side for recording. That is, there is no need to form a recording mark by condensing two light beams at the same position as in the case of the positive micro-hologram method.
Further, in comparison with the negative type micro hologram method, there is an advantage that the initialization process can be made unnecessary.
Note that Patent Document 2 shows an example in which pre-cure light irradiation is performed before performing void recording, but void recording is possible even if such pre-cure light irradiation is omitted.

By the way, a bulk recording type (also simply referred to as a bulk type) optical disc recording medium for which various recording methods as described above have been proposed, the recording layer (bulk layer) of such a bulk type optical disc recording medium is For example, it does not have an explicit multilayer structure in the sense that a plurality of reflective films are formed. That is, the bulk layer 102 is not provided with a reflection film and a guide groove for each recording layer as provided in a normal multilayer disc.
Therefore, with the structure of the bulk type recording medium 100 shown in FIG. 12, the focus servo and tracking servo cannot be performed at the time of recording in which the mark is not formed.

Therefore, in practice, the bulk type recording medium 100 is provided with a reference reflecting surface (reference surface) having a guide groove as shown in FIG.
Specifically, for example, guide grooves (position guides) formed by forming pits or grooves are formed in a spiral shape or a concentric shape on the lower surface side of the cover layer 101, and a selective reflection film 103 is formed thereon. Then, on the lower layer side of the cover layer 102 on which the selective reflection film 103 is thus formed, the bulk layer 102 is laminated via an adhesive material such as a UV curable resin as the intermediate layer 104 in the figure. .
Here, recording of absolute position information (address information) such as radial position information and rotation angle information is performed by forming the guide groove by the pits and grooves as described above. In the following description, the surface on which such guide grooves are formed and the absolute position information is recorded (in this case, the surface on which the selective reflection film 103 is formed) is referred to as “reference surface Ref”.

Further, with the medium structure as described above, a laser beam for recording (or reproducing) a mark (hereinafter referred to as recording / reproducing) is used for the bulk type recording medium 100 as shown in FIG. Separately from the laser light (also simply referred to as recording / reproducing light), servo laser light (also simply referred to as servo light) as position control laser light is irradiated.
As shown in the figure, the recording / reproducing laser beam and the servo laser beam are applied to the bulk type recording medium 100 through a common objective lens.

  At this time, if the servo laser light reaches the bulk layer 102, there is a possibility that the mark recording in the bulk layer 102 is adversely affected. For this reason, in the conventional bulk recording method, a laser beam having a wavelength band different from that of the recording / playback laser beam is used as the servo laser beam, and the reflection film formed on the reference surface Ref is: A selective reflection film 103 having wavelength selectivity of reflecting the servo laser beam and transmitting the recording / reproducing laser beam is provided.

Based on the above premise, the operation at the time of mark recording on the bulk type recording medium 100 will be described with reference to FIG.
First, when performing multi-layer recording on the bulk layer 102 on which no guide groove or reflective film is formed, it is determined in advance which position the layer position where the mark is recorded in the depth direction in the bulk layer 102 is set. It will be decided. In the figure, as the layer position (mark formation layer position: also referred to as information recording layer position) for forming a mark in the bulk layer 102, a total of five pieces of information, that is, a first information recording layer position L1 to a fifth information recording layer position L5. The case where the recording layer position L is set is illustrated. As shown in the figure, the first information recording layer position L1 is set as a position separated from the selective reflection film 103 (reference surface Ref) where the guide groove is formed by the first offset of-L1 in the focus direction (depth direction). Is done. In addition, the second information recording layer position L2, the third information recording layer position L3, the fourth information recording layer position L4, and the fifth information recording layer position L5 are respectively the second offset of-L2 from the reference plane Ref and the third information recording layer position L5. The positions are set apart by an offset of-L3, a fourth offset of-L4, and a fifth offset of-L5.

  At the time of recording in which the mark is not yet formed, focus servo and tracking servo for each layer position in the bulk layer 102 cannot be performed based on the reflected light of the recording / reproducing laser beam. Therefore, the focus servo control and tracking servo control of the objective lens during recording are performed based on the reflected light of the servo laser light so that the spot position of the servo laser light follows the guide groove on the reference surface Ref. become.

  However, the upper recording reuse laser beam needs to reach the bulk layer 102 formed on the lower layer side than the reference surface Ref for mark recording. For this reason, the optical system in this case is provided with a recording / reproducing light focusing mechanism for independently adjusting the focusing position of the recording / reproducing laser beam, in addition to the focusing mechanism of the objective lens. .

Here, FIG. 17 shows an outline of an optical system for recording / reproducing the bulk type recording medium 100 including a mechanism for independently adjusting the focusing position of the recording / reproducing laser beam. Keep it.
In FIG. 17, the objective lens also shown in FIG. 16 has a radial direction (tracking direction) of the bulk type recording medium 100 and a direction in which it contacts and separates from the bulk type recording medium 100 (focus direction) by a biaxial actuator as shown. Can be displaced.

  In FIG. 17, the mechanism for independently adjusting the focusing position of the recording / reproducing laser beam corresponds to the focus mechanism (expander) in the drawing. Specifically, the focus mechanism as the expander includes a fixed lens and a movable lens held by a lens driving unit so as to be displaceable in a direction parallel to the optical axis of the recording / reproducing laser beam. When the movable lens is driven by the lens driving unit, the collimation of the recording / reproducing laser beam incident on the objective lens in the figure is changed, so that the focusing position of the recording / reproducing laser beam is changed to the servo laser. It is adjusted independently of light.

Further, as described above, the recording / playback laser beam and the servo laser beam have different wavelength bands, and accordingly, in this case, the optical system in this case uses a dichroic prism in the drawing to record / playback. The reflected laser beam and servo laser beam reflected from the bulk type recording medium 100 are separated into the respective systems (that is, each reflected light can be detected independently).
Further, in the case of forward light, the dichroic prism has a function of combining the recording / reproducing laser beam and the servo laser beam on the same axis and causing them to enter the objective lens. Specifically, in this case, the recording / reproducing laser beam is reflected by the mirror via the expander as shown in the figure, and then reflected by the selective reflection surface of the dichroic prism and enters the objective lens. On the other hand, the servo laser light passes through the selective reflection surface of the dichroic prism and enters the objective lens.

FIG. 18 is a diagram for explaining servo control during reproduction of the bulk type recording medium 100.
When reproduction is performed on the bulk type recording medium 100 on which mark recording has already been performed, there is no need to control the position of the objective lens based on the reflected light of the servo laser light as in recording. That is, at the time of reproduction, the mark row formed at the information recording layer position L to be reproduced (also referred to as the information recording layer L at the time of reproduction) is used as an object based on the reflected light of the recording / reproducing laser beam. Lens focus servo control and tracking servo control may be performed.

As described above, in the bulk recording method, recording / reproducing laser light for performing mark recording / reproduction and servo light as position control light are transmitted to the bulk type recording medium 100 through a common objective lens. Focus servo control and tracking servo control of the objective lens so that the servo laser light follows the position guide on the reference surface Ref during recording after being irradiated (combined on the same optical axis) And by separately adjusting the focusing position of the recording / reproducing laser beam by the recording / reproducing light focus mechanism, even if the guide groove is not formed in the bulk layer 102, a required position ( It is designed so that mark recording can be performed in the depth direction and tracking direction.
At the time of reproduction, focus servo control and tracking servo control of the objective lens based on the reflected light of the recording / reproducing laser beam are performed so that the focal position of the recording / reproducing laser beam follows the already recorded mark row. Thus, the mark recorded in the bulk layer 102 can be reproduced.

  Here, when the bulk recording method as described above is adopted, the recording / reproducing laser beam and the recording / reproducing laser light are generated along with the occurrence of a so-called skew (tilt) and the occurrence of lens shift of the objective lens due to the disk eccentricity. It is known that a spot position shift in the recording surface direction occurs in the servo laser beam.

FIG. 19 schematically shows a spot position deviation between the recording / reproducing laser beam and the servo laser beam accompanying the generation of skew.
In the state without skew shown in FIG. 19A, the spot positions of the servo laser beam and the recording / reproducing laser beam coincide with each other in the in-recording direction. On the other hand, in response to the occurrence of skew as shown in FIG. 19B, the optical axis shift occurs between the servo laser beam and the recording / playback laser beam, and the spot position shift Δx as shown in the figure. Will occur.

FIG. 20 schematically shows a spot position shift between the recording / reproducing laser beam and the servo laser beam accompanying the lens shift.
In the state without lens shift shown in FIG. 20A, the objective lens is at the reference position, and the center of the objective lens coincides with the optical axis c of each laser beam incident on the objective lens. The optical system is designed so that the spot positions of the laser beams in the recording surface direction coincide with each other when the objective lens is at the reference position.

On the other hand, when the objective lens is shifted from the reference position so as to follow the disk eccentricity by tracking servo control as shown in FIG. 20B (in this case, the shift is to the left in the drawing). ) Causes a spot position deviation Δx as shown in the figure.
Such a spot position shift caused by the lens shift is caused by a difference in incidence of the servo laser light and the recording / reproducing laser light with respect to the objective lens. Specifically, the servo laser light is incident on the objective lens as substantially parallel light, whereas the recording / reproducing laser light is incident as non-parallel light.

  When the spot position shift between the servo laser beam and the recording / reproducing laser beam due to such skew or lens shift occurs, the information recording position shift in the bulk layer 102 occurs. That is, as understood from the above description, the spot position of the recording / reproducing laser beam at the time of recording is controlled by performing tracking servo control of the objective lens based on the reflected light of the servo laser beam. In response to the occurrence of the spot position deviation as described above, it becomes impossible to perform recording at an intended position in the bulk layer 102.

At this time, depending on the setting of skew / eccentricity and track pitch (position guide formation interval), the information recording positions may overlap between adjacent tracks. Specifically, disk eccentricity and skew may occur in different modes each time a disk is loaded depending on how the disk is clamped to the spindle motor. When the additional recording is performed, the mark / eccentric aspect generated at the time of the previous recording and the skew / eccentric aspect generated at the time of the additional recording are different from each other. There arises a problem that the columns overlap each other and sometimes cross.
If this is the case, the recorded signal cannot be reproduced correctly.

One technique for preventing the occurrence of such overlapping and crossing of mark rows is to set the track pitch on the reference surface Ref wider.
However, when the track pitch of the reference surface Ref is increased in this way, it is a matter of course that the recording capacity in the bulk layer 102 is reduced.

Therefore, in order to prevent the displacement of the information recording position itself, it is conceivable to correct the spot position deviation of the recording / reproducing laser beam from the result of detecting skew and lens shift.
Specifically, as can be understood with reference to FIGS. 19 and 20, since the skew generation amount and the spot position deviation amount, and the lens shift amount and the spot position deviation amount are in a proportional relationship, the detection result of the skew amount is obtained. The spot position deviation correction amount corresponding to skew is obtained from the above, and the spot position deviation correction amount corresponding to lens shift is obtained from the detection result of the lens shift amount, and the sum thereof is attributed to both skew and lens shift. It is calculated as a correction amount for correcting the spot position deviation.
Based on the correction amount calculated in this manner, for example, the optical axis of the recording / reproducing laser beam is moved in parallel to correct the spot position deviation between the servo laser beam and the recording / reproducing laser beam.

  However, when the above-described spot position deviation correction is performed, a configuration for detecting the amount of skew and lens shift is required. That is, the cost and the size of the apparatus are increased accordingly.

Further, referring to FIG. 19 and FIG. 20, the spot position deviation does not only change according to the skew amount or the lens shift amount, but also changes depending on the layer position to be recorded. I understand. In addition, due to secular change or the like, there may be a change in the detected skew amount / lens shift amount and the actually required correction amount.
As understood from these points, there is a possibility that the deviation of the information recording position cannot be properly corrected by the method of correcting the spot position deviation based on the detected skew amount / lens shift amount.

In view of the above problems, the present invention is configured as follows as an optical drive device.
That is, the optical drive device of the present invention includes a reference surface having a reflective film in which a track as a position guide is formed in a spiral shape or a concentric shape, and a recording layer on which information recording is performed by mark formation according to light irradiation. And an optical drive device that performs at least recording on an optical disk recording medium in which a reference track is formed at the same radial position as a predetermined track on the reference surface in the recording layer, The first light for recording information on the light and the second light for performing position control based on the position guide formed on the reference surface are incident, and the first light and the second light An objective lens for irradiating both the light to the optical disk recording medium is provided.
In addition, a tracking mechanism that drives the objective lens in a tracking direction that is parallel to the radial direction of the optical disk recording medium is provided.
In addition, an optical axis adjustment unit that changes a relative positional relationship between the optical axes of the first light and the second light incident on the objective lens is provided.
A first tracking servo signal generation unit configured to generate a first tracking servo signal from a tracking error signal obtained by receiving reflected light of the first light from the optical disc recording medium;
A second tracking servo signal generation unit configured to generate a second tracking servo signal from a tracking error signal obtained by receiving reflected light of the second light from the optical disc recording medium;
The optical axis adjustment unit includes a correction amount detection unit that detects an optical axis correction amount.
Then, the tracking servo control for the second light based on the second tracking servo signal by the tracking mechanism causes the spot position of the second light to follow the predetermined track on the reference plane. Meanwhile, the optical axis adjustment unit executes tracking servo control for the first light based on the first tracking servo signal, and the spot position of the first light is changed to the reference track in the recording layer. In the state of tracking the optical axis, the correction amount of the optical axis detected by the correction amount detector is sampled for each rotation angle of the optical disk recording medium,
A control unit that instructs the optical axis adjustment unit to execute the correction of the optical axis by instructing the correction amount sampled for each rotation angle;

As described above, in the present invention, an ideal correction state is created by using the reference track formed on the optical disc recording medium so that the spot positions of the first light and the second light coincide in the radial direction. In this state, the correction amount of the optical axis by the optical axis adjustment unit is sampled for each rotation angle. Then, the spot position deviation is corrected using the correction amount sampled for each rotation angle in this way.
According to this, it is possible to omit a configuration for detecting the skew amount and the lens shift amount of the objective lens in correcting the spot position deviation.
In addition, since an ideal correction state is created as described above and the correction operation is performed using a correction amount actually sampled, it is possible to perform an appropriate correction according to a change with time and the like, and It is also possible to perform correction with an appropriate correction amount according to the formation layer. That is, from these points, the spot position deviation (information recording position deviation due to the first light) can be corrected with higher accuracy.

As described above, according to the present invention, it is possible to omit the configuration for detecting the skew amount and the lens shift amount of the objective lens in correcting the spot position deviation, and to correct the information recording position by the first light. Can be performed with higher accuracy.
Since the configuration for detecting the skew / lens shift amount is not required, the apparatus can be reduced in size and cost.

  In addition, if the information recording position can be corrected with higher accuracy, the track pitch on the reference surface (the distance between the position guides in the radial direction) can be reduced correspondingly, resulting in an increase in recording capacity. Is planned.

  Further, since the track pitch can be reduced, the access time can be shortened accordingly. That is, when the track pitch is wide, it takes a long time to search the recorded data string. However, this is alleviated and the access time is shortened in the present invention.

1 is a cross-sectional structure diagram of an optical disc recording medium to be recorded / reproduced in an embodiment. It is a figure for demonstrating the reference track formed in an optical disk recording medium. It is the figure which showed the internal structure of the optical pick-up with which the optical drive apparatus as embodiment is provided. It is the figure which showed the whole internal structure of the optical drive apparatus as embodiment. It is a figure for demonstrating the operation | movement at the time of sampling of correction amount. It is the figure which showed the data structure example of table information. It is the flowchart which showed the procedure of the specific process for implement | achieving the correction amount sampling operation | movement as embodiment. It is the flowchart which showed the procedure of the specific process which should be performed corresponding to the time of the correction | amendment operation | movement based on the sampled correction amount. It is explanatory drawing about the modification which provides a reference | standard track | truck in several layer position. It is explanatory drawing about the modification which provides a reference | standard track in a some radial position. It is a cross-sectional structure diagram of a multilayer recording medium. It is a figure for demonstrating a bulk recording system. It is a figure for demonstrating a micro hologram system. It is a figure for demonstrating a negative type | mold micro hologram system. It is the figure which illustrated cross-sectional structure of the actual bulk type recording medium provided with a reference plane. It is a figure for demonstrating the operation | movement at the time of the mark recording with respect to a bulk type recording medium. It is the figure which showed the outline | summary of the optical system for performing the recording / reproducing of a bulk type recording medium. It is a figure for demonstrating the servo control at the time of reproduction | regeneration of a bulk type recording medium. It is the figure which showed typically the spot position shift of the laser beam for recording and servo accompanying a skew. It is the figure which showed typically the spot position shift of the recording / reproducing laser beam and servo laser beam accompanying a lens shift.

Hereinafter, the best mode for carrying out the invention (hereinafter referred to as an embodiment) will be described.
The description will be made in the following order.

<1. Optical Disc Recording Medium to be Recorded / Reproduced in Embodiment>
<2. Configuration of optical drive device>
<3. Example of Correction Operation as Embodiment>
<4. Processing procedure>
<5. Summary>
<6. Modification>

<1. Optical Disc Recording Medium to be Recorded / Reproduced in Embodiment>

FIG. 1 shows a cross-sectional structure diagram of an optical disc recording medium to be recorded / reproduced in the embodiment.
An optical disk recording medium to be recorded / reproduced in the embodiment is a so-called bulk recording type optical recording medium, and is hereinafter referred to as a bulk type recording medium 1.
The bulk type recording medium 1 is a disc-shaped optical recording medium, and the bulk type recording medium 1 that is rotationally driven is irradiated with laser light to perform mark recording (information recording). In addition, the reproduction of the recorded information is also performed by irradiating the bulk type recording medium 1 that is rotationally driven with laser light.
The optical recording medium is a general term for recording media on which information is recorded / reproduced by light irradiation.

As shown in FIG. 1, a cover type 2, a selective reflection film 3, an intermediate layer 4, and a bulk layer 5 are formed in order from the upper layer side on the bulk type recording medium 1.
Here, the “upper layer side” in this specification refers to the upper layer side when a surface on which a laser beam from an optical drive device (recording / reproducing device 10) side as an embodiment described later is incident is an upper surface.

  In this specification, the term “depth direction” is used, and this “depth direction” is a direction that coincides with the vertical direction according to the definition of “upper layer side” (that is, from the optical drive device side). The direction parallel to the incident direction of the laser beam (focus direction).

In the bulk type recording medium 1, the cover layer 2 is made of a resin such as polycarbonate or acrylic, and a guide groove is provided as a position guide for guiding the recording / reproducing position on the lower surface side as shown in the figure. It is formed and given an uneven cross-sectional shape as shown in the figure. The position guide is formed in a spiral shape or a concentric shape. In the case of this example, the following description will be continued on the assumption that the position guide is formed in a spiral shape.
The guide groove is formed by a continuous groove (groove) or a pit row. For example, when the guide groove is formed of a pit row, position information (absolute position information: rotation angle information as information representing a rotation angle position on the disk, radial position information, etc.) is determined by a combination of pit and land lengths. Is recorded. Alternatively, when the guide groove is a groove, position information is recorded based on the meandering period information by periodically wobbling the groove.
The cover layer 2 is generated by, for example, injection molding using a stamper in which such guide grooves (uneven shape) are formed.

A selective reflection film 3 is formed on the lower surface side of the cover layer 2 where the guide groove is formed.
Here, as described above, in the bulk recording method, separately from the light for recording / reproducing the mark on / from the bulk layer 5 as the recording layer (recording / reproducing laser beam), the above-described guide groove is used. It is assumed that light (servo laser light) for obtaining tracking and focus error signals is separately irradiated.
At this time, if the servo laser light reaches the bulk layer 5, there is a risk of adversely affecting mark recording in the bulk layer 5. Therefore, there is a need for a reflective film having selectivity that reflects servo laser light and transmits recording / reproducing laser light.
Conventionally, in the bulk recording method, the laser beam for recording / playback and the laser beam for servo use laser beams having different wavelength bands, and in order to cope with this, the selective reflection film 3 is used for servo. A selective reflection film having wavelength selectivity is used in which light in the same wavelength band as the laser light is reflected and light having other wavelengths is transmitted.

On the lower layer side of the selective reflection film 3, a bulk layer 5 as a recording layer is laminated (adhered) through an intermediate layer 4 made of an adhesive material such as UV curable resin.
As a material for forming the bulk layer 5 (recording material), for example, an optimal material is appropriately selected according to the bulk recording method to be employed, such as the positive micro hologram method, the negative micro hologram method, or the void recording method described above. It only has to be done.
The mark recording method for the optical disc recording medium targeted by the present invention is not particularly limited, and any method may be adopted in the category of the bulk recording method. In the following description, as an example, a case where a void recording method is adopted is illustrated.

  Here, in the bulk-type recording medium 1 having the above-described configuration, the selective reflection film 3 on which the position guide as the above-described guide groove is formed is used for recording / reproducing based on servo laser light as will be described later. The reflection surface is a reference for performing laser beam position control. In this sense, the surface on which the selective reflection film 3 is formed is hereinafter referred to as a reference surface Ref.

As described above with reference to FIG. 16, in the bulk type optical recording medium, in order to perform multilayer recording in the bulk layer, each layer position (information recording layer position L) where information recording is to be performed is set in advance. . Also in the bulk type recording medium 1, the information recording layer position L is the first offset of-L1, the second offset of-L2, the first offset in the depth direction from the reference plane Ref, as in the case of FIG. The first information recording layer position L, the second information recording layer position L2, the third information recording layer position L3, and the fourth information separated by 3 offsets of-L3, 4th offset of-L4, and 5th offset of-L5. Assume that the recording layer position L4 and the fifth information recording layer position L5 are set.
Information of the offset of-L from the reference plane Ref to each layer position L is set for the controller 40 in the recording / reproducing apparatus 10 described later.

Further, in the bulk type recording medium 1 of the present embodiment, a reference track (intra-bulk layer reference track) TR-bl as shown in FIG.
The reference track TR-bl in the bulk layer 5 is one track selected from the tracks formed on the reference surface Ref (the reference track TR-rf on the reference surface or simply the reference track TR-bl). rf) and the same radial position.
As an example, it is assumed that the reference track TR-bl in this example is formed at a position separated from the reference plane Ref by the offset of-L3 in the depth direction as shown in the figure. That is, the reference track TR-bl in this case is formed at the information recording layer position L3.

The reference track TR-bl can be formed, for example, by forming a mark row using a writer adjusted with high accuracy. Specifically, a writer adjusted with high accuracy is used so that the spot position deviation between the recording / reproducing laser beam and the servo laser beam due to skew or lens shift can be corrected almost completely.
Various methods other than the above method can be considered for accurately forming the reference track TR-bl so that the reference track TR-rf has the same radial position as the reference track TR-rf on the reference surface Ref, and should be particularly limited here. It is not a thing.
Further, the reference track TR-bl can be formed not by a mark row (intermittently formed mark) but by a DC mark (continuously formed mark).

<2. Configuration of optical drive device>

3 and 4 show an internal configuration of an optical drive device (referred to as a recording / reproducing device 10) as an embodiment for performing recording / reproducing with respect to the bulk type recording medium 1 having the structure shown in FIGS. It is a figure for demonstrating.
3 mainly shows the internal configuration of the optical pickup OP provided in the recording / reproducing apparatus 10 of the embodiment, and FIG. 4 shows the overall internal configuration of the recording / reproducing apparatus 10 including the optical pickup OP.

In FIG. 3, the bulk type recording medium 1 loaded in the recording / reproducing apparatus 10 is set so that the center hole is clamped at a predetermined position in the recording / reproducing apparatus 10, and is rotated by a spindle motor (not shown). Is kept in a possible state.
The optical pickup OP is provided for irradiating the bulk type recording medium 1 rotated by the spindle motor with recording / reproducing laser light and servo laser light.

In the optical pickup OP, a recording / reproducing laser 11 which is a light source of a recording / reproducing laser beam for recording information by the mark and reproducing information recorded by the mark, and a guide groove formed on the reference surface Ref And a servo laser 24 which is a light source of servo laser light which is light for performing position control using the.
Here, as described above, the recording / reproducing laser beam and the servo laser beam have different wavelengths. In this example, the recording / reproducing laser beam has a wavelength of about 405 nm (so-called blue-violet laser beam), and the servo laser beam has a wavelength of about 650 nm (red laser beam).

In addition, an objective lens 20 serving as an output end of the recording / reproducing laser beam and the servo laser beam to the bulk type recording medium 1 is provided in the optical pickup OP.
Further, the recording / reproducing light receiving unit 23 for receiving the reflected light of the upper recording / reuse laser beam from the bulk type recording medium 1 and the reflected light of the servo laser beam from the bulk type recording medium 1 are received. And a servo light receiving portion 29 for this purpose.

  In addition, in the optical pickup OP, the recording / reproducing laser beam emitted from the upper recording / reusing laser 11 is guided to the objective lens 20 and from the bulk type recording medium 1 incident on the objective lens 20. An optical system for guiding the reflected light of the recording / reproducing laser beam to the upper recording / reproducing light receiving unit 23 is formed.

  Specifically, the recording / reproducing laser beam emitted from the upper recording / reproducing laser 11 is made parallel light through the collimation lens 12 and then enters the polarization beam splitter 13. The polarization beam splitter 13 is configured to transmit the recording / reproducing laser light incident from the recording / reproducing laser 11 side as described above.

The recording / reproducing laser light transmitted through the polarizing beam splitter 13 is incident on an expander including a shift lens 14A, a movable lens 15, and a lens driving unit 16. In this expander, the side closer to the recording / reproducing laser 11 as the light source is a shift lens 14A, the movable lens 15 is disposed on the side far from the recording / reproducing laser 11, and the movable lens 15 is recorded / reproduced by the lens driving unit 16. Independent focus control is performed on the recording / reproducing laser beam by being driven in a direction parallel to the optical axis of the recording laser beam. This expander corresponds to the recording / reproducing light focusing mechanism described above (see FIG. 17).
As will be described later, the recording / reproducing light focusing mechanism (the lens driving unit 16) is offset by offset-L set in correspondence with the target information recording layer position L by the controller 40 shown in FIG. It is driven according to the value of.

Further, in this case, the shift lens 14A in the upper recording / relighting focusing mechanism is held so as to be displaceable in a direction perpendicular to the incident optical axis by the lens driving unit 14B in the drawing. In this case, the lens driving unit 14B is configured to displace the shift lens 14A in a direction parallel to the radial direction of the bulk type recording medium 1. That is, by the shift of the shift lens 14A by the lens driving unit 14B, the optical axis of the recording / reproducing laser beam irradiated to the bulk type recording medium 1 through the objective lens 20 is shifted in a direction parallel to the radial direction. It is something that can be done.
Here, the lens driving unit 14B provided to shift the optical axis of the recording / reproducing laser beam in this way is hereinafter also referred to as a beam shifter 14B.
The beam shifter 14B is configured to shift the shift lens 14A by, for example, a voice coil motor (VCM), and is driven and controlled by a drive signal D-bs from a driver 39 described later.

The recording / reproducing laser beam through the shift lens 14A and the movable lens 15 forming the upper recording / reproducing focus mechanism is reflected by the mirror 17 as shown in the figure, and then dichroic through the quarter wavelength plate 18. The light enters the prism 19.
The dichroic prism 19 is configured such that its selective reflection surface reflects light in the same wavelength band as the recording / reproducing laser beam, and transmits light of other wavelengths. Accordingly, the recording / reproducing laser beam incident as described above is reflected by the dichroic prism 19.

The recording / reproducing laser beam reflected by the dichroic prism 19 is applied to the bulk type recording medium 1 through the objective lens 20 as shown in the figure.
With respect to the objective lens 20, the objective lens 20 is focused in the focus direction (the direction in which the objective lens 20 is moved toward and away from the bulk type recording medium 1) and the tracking direction (the direction perpendicular to the focus direction: the radial direction of the bulk type recording medium 1). ) Is provided with a biaxial actuator 21 that is held displaceably.
The biaxial actuator 21 is provided with a focus coil and a tracking coil, and is supplied with drive signals (drive signals FD and TD, which will be described later), thereby displacing the objective lens 20 in the focus direction and the tracking direction, respectively.

Here, at the time of reproduction, the bulk type recording medium 1 (information to be reproduced in the bulk layer 5) in response to the recording / reproducing laser light being irradiated onto the bulk type recording medium 1 as described above. The reflected light of the upper recording reuse laser beam is obtained from the mark row recorded on the recording layer L). The reflected light of the recording / reproducing laser beam thus obtained is guided to the dichroic prism 19 through the objective lens 20 and reflected by the dichroic prism 19.
The reflected light of the recording / reproducing laser beam reflected by the dichroic prism 19 passes through the ¼ wavelength plate 18 → mirror 17 → recording / reproducing light focusing mechanism (movable lens 15 → shift lens 14A), and then is a polarization beam splitter. 13 is incident.

  Here, the reflected light (return light) of the recording / reproducing laser light incident on the polarization beam splitter 13 in this way is due to the action by the quarter wavelength plate 18 and the action at the time of reflection by the bulk type recording medium 1. The polarization direction of the recording / reproducing laser beam (outgoing light) incident on the polarization beam splitter 13 from the recording / reproducing laser beam 11 side is different by 90 degrees. As a result, the reflected light of the recording / reproducing laser beam incident as described above is reflected by the polarization beam splitter 13.

  Thus, the reflected light of the recording / reproducing laser beam reflected by the polarization beam splitter 13 is condensed on the light receiving surface of the recording / reproducing light receiving unit 23 via the condenser lens 22.

Further, in the optical pickup OP, in addition to the configuration of the optical system for the recording / reproducing laser beam described above, the servo laser beam emitted from the servo laser 24 is guided to the objective lens 20 and the objective lens 20 is used. An optical system for guiding the reflected light of the servo laser light from the bulk type recording medium 1 incident on the lens 20 to the servo light receiving portion 29 is formed.
As shown in the drawing, the servo laser light emitted from the servo laser 24 is converted into parallel light through the collimation lens 25 and then enters the polarization beam splitter 26. The polarization beam splitter 26 is configured to transmit the servo laser light (outgoing light) incident from the servo laser 24 side in this way.

The servo laser light transmitted through the polarization beam splitter 26 is incident on the dichroic prism 19 via the quarter wavelength plate 27.
As described above, the dichroic prism 19 is configured to reflect light in the same wavelength band as that of the recording / reproducing laser beam and transmit light of other wavelengths. The light passes through the dichroic prism 19 and is irradiated onto the bulk type recording medium 1 through the objective lens 20.

Further, the reflected light of the servo laser light (reflected light from the reference surface Ref) obtained in response to the irradiation of the servo laser light on the bulk type recording medium 1 passes through the objective lens 20. The light passes through the rear dichroic prism 19 and enters the polarization beam splitter 26 via the quarter-wave plate 27.
In the same manner as in the case of the previous recording / reproducing laser beam, the reflected light (return light) of the servo laser beam incident from the bulk type recording medium 1 side is the action of the quarter wavelength plate 27 and the bulk type. Due to the action at the time of reflection on the recording medium 1, the polarization direction differs from that of the forward light by 90 degrees, and the reflected light of the servo laser light as the backward light is reflected by the polarization beam splitter 26.

  The reflected light of the servo laser light reflected by the polarization beam splitter 26 is condensed on the light receiving surface of the servo light receiving unit 29 via the condenser lens 28.

  Here, although description by illustration is omitted, the recording / reproducing apparatus 10 is actually provided with a slide drive unit that slides the entire optical pickup OP described above in the tracking direction, and the optical pickup OP by the slide drive unit is provided. By driving this, the irradiation position of the laser beam can be displaced over a wide range.

In this case, a position sensor 31 is provided in the optical pickup OP.
The position sensor 31 is provided in the vicinity of the shift lens 14A, and detects the position (displacement amount from the reference position) of the shift lens 14A in the tracking direction. A position detection signal ps-sh for the shift lens 14 </ b> A by the position sensor 31 is supplied to the controller 40.

  For confirmation, the position detection signal ps-sh from the position sensor 31 is the optical axis correction amount when correcting the spot position deviation between the recording / reproducing laser beam and the servo laser beam. It functions as a signal representing.

The overall internal configuration of the recording / reproducing apparatus 10 is as shown in FIG.
In FIG. 4, only a part of the internal configuration of the optical pickup OP is extracted and shown.

  In FIG. 4, the recording / reproducing apparatus 10 includes a signal processing system for performing recording / reproduction for the bulk layer 5 and focus / tracking control of the objective lens 20 at the time of mark recording / reproduction. Recording / reproducing light matrix circuit 33, reproduction processing unit 34, recording / reproducing light servo circuit 35, servo light matrix circuit 36, position information detecting unit 37, and servo light servo circuit 38. ing.

Data to be recorded on the bulk type recording medium 1 (recording data) is input to the recording processing unit 32. The recording processing unit 32 adds an error correction code to the input recording data or performs predetermined recording modulation encoding, for example, “0” “1” actually recorded on the bulk type recording medium 1. A recording modulation data string which is a binary data string is obtained.
The recording processing unit 32 performs light emission driving of the recording / reproducing laser 11 in the optical pickup OP by the recording pulse RCP based on the recording modulation data string generated in this way.

The recording / reproducing light matrix circuit 33 corresponds to the light reception signals DT-rp (output current) from a plurality of light receiving elements as the recording / reproducing light receiving unit 23 shown in FIG. An amplifier circuit is provided, and necessary signals are generated by matrix calculation processing.
Specifically, a high-frequency signal (hereinafter referred to as a reproduction signal RF) corresponding to a reproduction signal obtained by reproducing the recording modulation data string described above, a focus error signal FE-rp for focus servo control, and a tracking servo control. A tracking error signal TE-rp is generated.

The reproduction signal RF generated by the recording / reproducing light matrix circuit 33 is supplied to the reproduction processing unit 34.
The focus error signal FE-rp and the tracking error signal TE-rp are supplied to the recording / reproducing light servo circuit 35.

  The reproduction processing unit 34 performs reproduction processing for restoring the recording data, such as binarization processing, recording modulation code decoding / error correction processing, and the like to reproduce the recording data. Get the data.

The recording / reproducing light servo circuit 35 generates a focus servo signal FS-rp and a tracking servo signal TS-rp based on the focus error signal FE-rp and the tracking error signal TE-rp supplied from the matrix circuit 33, respectively. By driving the focus coil and tracking coil of the biaxial actuator 21 based on the focus drive signal FD-rp based on the focus servo signal FS-rp, the tracking servo signal TS-rp, and the tracking drive signal TD-rp, recording is performed. Realizes focus servo control and tracking servo control for reused laser light.
As can be understood from the above description, the servo control of the biaxial actuator 21 (objective lens 20) based on the reflected light of the recording / reproducing laser beam is performed during reproduction.

  In addition, the recording / reproducing light servo circuit 35 realizes a track jump operation by turning off the tracking servo loop and giving a jump pulse to the tracking coil in response to an instruction given from the controller 40 at the time of reproduction. Also performs tracking servo pull-in control. Also, focus servo pull-in control is performed.

  The recording / reproducing servo circuit 35 receives the tracking drive signal TD-rp generated based on the tracking servo signal TS-rp in response to an instruction given from the controller 40 in response to a correction amount sampling operation described later. This will be output to the driver 39, which will be described later.

In the signal processing system for the reflected light of the servo laser light, the servo light matrix circuit 36 is based on the light reception signals DT-sv from the plurality of light receiving elements in the servo light receiving unit 29 shown in FIG. Generate the necessary signals.
Specifically, the servo light matrix circuit 36 generates a focus error signal FE-sv and a tracking error signal TE-sv for each servo control of focus / tracking.
Further, a position information detection signal Dps for detecting absolute position information (address information) recorded on the reference surface Ref is generated. For example, when absolute position information is recorded by a pit string, a sum signal is generated as the position information detection signal Dps. Alternatively, when the absolute position information is recorded by the wobbling groove, a push-pull signal is generated as the position information detection signal Dps.

  The position information detection signal Dps is supplied to the position information detection unit 37. The position information detection unit 37 detects absolute position information recorded on the reference surface Ref based on the position information detection signal Dps. The detected absolute position information is supplied to the controller 40.

The focus error signal FE-sv and the tracking error signal TE-sv generated by the servo light matrix circuit 36 are supplied to the servo light servo circuit 38.
The servo light servo circuit 38 generates a focus servo signal FS-sv and a tracking servo signal TS-sv based on the focus error signal FE-sv and the tracking error signal TE-sv, respectively.
At the time of recording, in accordance with an instruction from the controller 40, the focus drive signal FD-sv generated based on the focus servo signal FS-sv and the tracking servo signal TS-sv and the tracking drive signal TD-sv are set to 2 By driving the focus coil and tracking coil of the shaft actuator 21, focus servo control and tracking servo control for the servo laser beam are realized.

  The servo light servo circuit 38 performs a track jump operation by turning off the tracking servo loop and giving a jump pulse to the tracking coil of the biaxial actuator 21 in response to an instruction given from the controller 40 in response to recording. Realization and tracking servo pull-in control. Also, focus servo pull-in control with respect to the reference surface Ref is performed.

The controller 40 includes a microcomputer having a memory (storage device) such as a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), for example, and a program stored in the ROM or the like, for example. The overall control of the recording / reproducing apparatus 10 is performed by executing the control and processing according to the above.
Specifically, the controller 40 controls (sets) the focusing position of the recording / reproducing laser beam based on the value of the offset of-L set in advance corresponding to each layer position as described above. More specifically, the controller 40 drives the lens driving unit 16 in the optical pickup OP based on the value of the offset of-L set corresponding to the information recording layer position L to be recorded, thereby obtaining a depth. The recording position in the vertical direction is selected.

The controller 40 also performs control for realizing the servo control switching of the objective lens 20 at the time of recording / reproduction as described above with reference to FIGS. Specifically, at the time of recording, the controller 40 instructs the servo light servo circuit 38 to output the focus drive signal FD-sv and the tracking drive signal TD-sv, and the recording / playback light servo circuit 35 performs focus drive. An instruction is given to stop the output of the signal FD-rp and the tracking drive signal TD-rp.
On the other hand, at the time of reproduction, the recording / playback light servo circuit 35 is instructed to output the focus drive signal FD-rp and the tracking drive signal TD-rp, and the servo light servo circuit 38 is directed to the focus drive signal FD-rp. An instruction is given to stop the output of sv and tracking drive signal TD-sv.

  The controller 40 performs seek operation control on the servo light servo circuit 38. That is, the servo circuit 38 is instructed to move the spot position of the servo laser beam to a predetermined address on the reference plane Ref.

  Further, the controller 40 in this case realizes the correction operation as an embodiment by executing the processing operation described later with reference to FIGS. 7 and 8, which will be described later.

The driver 39 generates a drive signal D-bs based on the value of the correction amount instructed from the controller 40 in response to a correction operation described later, and drives the beam shifter 14B in the optical pickup OP based on the drive signal D-bs. Control. Thereby, the spot position deviation between the recording / reproducing laser beam and the servo laser beam due to the skew or the lens shift of the objective lens 20 is corrected.
Further, the driver 39 drives and controls the beam shifter 14B based on the tracking drive signal TD-rp supplied from the recording / reproducing light servo circuit 35 at the time of sampling of the correction amount, which will be described later. Tracking servo control is realized.

<3. Example of Correction Operation as Embodiment>

Here, as described above, also in the recording / reproducing apparatus 10 of the present embodiment, the reference surface having the reflective film in which the track as the position guide is formed in a spiral shape or a concentric shape, and the light irradiation according to the light irradiation. When recording on an optical disk recording medium having a recording layer on which information recording is performed by forming a mark, the optical disk recording medium is irradiated with a recording / playback laser beam and a servo laser beam through a common objective lens. The information recording position by the upper recording re-use laser beam is controlled by performing tracking servo control of the objective lens by the servo laser beam for the position guide formed on the reference surface. .
When such a configuration is adopted, as described with reference to FIGS. 19 and 20, the spot of the servo laser beam and the recording / reproducing laser beam due to skew or the lens shift of the objective lens. A positional deviation (that is, an information recording position deviation) occurs.
The present embodiment proposes a method of correcting such a shift in information recording position with higher accuracy while eliminating the need for a skew or lens shift detection unit.

  Specifically, in the present embodiment, the spot position of the recording / reproducing laser beam is tracked using the reference track TR-bl previously formed on the recording layer (bulk layer 5) as shown in FIG. The direction is forced to coincide with the spot position of the servo laser beam in the direction, and in this state, the correction amount required for each rotation angle is sampled. The correction amount sampled in this way is sequentially set for each rotation angle to correct the spot position deviation.

FIG. 5 is a diagram for explaining the correction amount sampling operation according to the present embodiment.
In FIG. 5, the bulk type recording medium 1, the shift lens 14A, the beam shifter 14B, the movable lens 15, the lens driving unit 16, the dichroic mirror 19, the objective lens 20 in the optical pickup OP shown in FIG. The biaxial actuator 21 is extracted and shown.

In sampling the correction amount, first, tracking servo control of the objective lens 20 is performed based on the reflected light of the servo laser light so that the servo laser light follows the reference track TR-rf on the reference surface Ref.
In this state, tracking servo control is performed by driving the beam shifter 14B so that the recording / reproducing laser beam follows the reference track TR-bl in the bulk layer 5 based on the reflected light of the recording / reproducing laser beam.
At this time, the formation layer of the reference track TR-bl is selected depending on the focus mechanism for recording / reproducing light (lens driving unit 16). Specifically, in this case, the information recording layer position L3 is selected.

  In this way, the spot positions of the recording / reproducing laser beam and the servo laser beam are forcibly matched in the tracking direction using the reference track TR-bl. That is, an ideal correction state in which the positions of the spots in the tracking direction coincide with each other is obtained.

  In the state in which the respective spot positions are matched as described above, the controller 40 determines the value of the position detection signal ps-sh (that is, the shift lens 14A of the shift lens 14A) based on the absolute position information detected by the position information detector 37. The correction amount) is sampled for each rotation angle of the bulk type recording medium 1 (that is, for each rotation angle value detected as absolute position information).

The controller 40 creates table information as shown in FIG. 6 based on the correction amount value sampled for each rotation angle.
As shown in FIG. 6, the table information is information storing correction amount values sampled for each rotation angle. Specifically, in this case, the sampled correction value is associated with each rotation angle of 1 °.
The table information is created in a memory provided in the controller 40, for example.

  When information is recorded on the bulk layer 5, the deviation of the information recording position is corrected using the table information created in this way. Specifically, the controller 40 determines the absolute position information (rotation angle information) supplied from the position information detection unit 37 and the contents of the table information in response to the start of recording on the bulk layer 5. Based on the above, an instruction of the value of the correction amount corresponding to the rotation angle of the bulk type recording medium 1 to the driver 39 is started. That is, the correction operation using the value of the correction amount sampled in advance is executed for each rotation angle of the bulk type recording medium 1.

Here, the correction amount sampling operation as described above can be performed in advance, for example, at the start-up operation after loading the disc or immediately before the start of the recording operation. Alternatively, it may be executed every predetermined time. In any case, the correction amount sampling operation is performed in advance before the start of the recording operation on the bulk layer 5.

<4. Processing procedure>

7 and 8 are flowcharts for explaining a specific processing procedure for realizing the correction operation as the embodiment described above.
FIG. 7 shows a procedure of processing to be executed corresponding to the correction amount sampling, and FIG. 8 shows a procedure of processing to be executed corresponding to the correction operation based on the sampled correction amount.
7 and 8, a process in which the controller 40 executes a specific processing procedure for realizing the correction operation according to the embodiment based on a program stored in a predetermined memory such as an internal ROM. Shown as a procedure.

  First, in FIG. 7, in step S101, processing for seeking near the reference track TR-rf with servo laser light is executed. That is, as a seek operation control for the servo circuit 38 for servo light, seek operation control is performed with an address near a predetermined reference track TR-rf on the reference surface Ref as a target.

In the subsequent step S102, processing for performing tracking servo pull-in of the recording / reproducing laser beam to the reference track TR-bl is executed. That is, in response to an instruction to the recording / reproducing light servo circuit 35, the output destination of the tracking drive signal TD-rp is selected by the driver 39 (the beam shifter 14B is driven based on the reflected light of the recording / reproducing laser beam). At the same time, an instruction is given to turn on the tracking servo loop.
Here, in response to the servo laser beam (objective lens 20) seeking near the reference track TR-rf, the spot position of the recording / reproducing laser beam is also positioned near the reference track TR-bl. Will be. Accordingly, by performing the tracking servo pull-in instruction for the recording / reproducing laser beam as described above in step S102, the spot position of the recording / reproducing laser beam may be set to the reference track TR- (although it may require several retries). Can be pulled into bl.
Note that after the servo laser beam reaches the reference track TR-rf, a tracking servo pull-in instruction for the recording / reproducing laser beam with respect to the reference track TR-bl may be issued.

In the next step S103, the process waits until the servo laser beam reaches the reference track TR-rf.
If a positive result is obtained in step S103 that the servo laser beam has reached the reference track TR-rf, the amount of movement of the beam shifter is sampled for each rotation angle in step S104 to create table information. .
That is, based on the rotation angle information supplied from the position information detection unit 37, the value of the position detection signal ps-sh by the position sensor 31 is sampled for each rotation angle of the bulk type recording medium 1, and the value and position of these rotation angles are sampled. The table information as shown in FIG. 6 is created in association with the value of the detection signal ps-sh (correction amount).
By executing the processing in step S104, a series of processing corresponding to the sampling of the correction amount shown in FIG.

Subsequently, a procedure of processing to be executed in response to the correction operation based on the sampled correction amount will be described with reference to FIG.
In FIG. 7, first, in step S201, the process waits until the recording start position is reached. When the recording start position is reached, output of a correction amount corresponding to the rotation angle is started in step S202. That is, the correction amount corresponding to the rotation angle of the bulk type recording medium 1 with respect to the driver 39 based on the rotation angle information supplied from the position information detection unit 37 and the contents of the table information created in advance in step S104. Starts the value indication.

In the subsequent step S203, the process waits until a state where recording should be ended is reached. When the recording is to be finished, the corresponding process at the time of the correction operation shown in this figure is finished.

<5. Summary>

As described above, in the present embodiment, the spot positions of the upper recording reuse laser beam and the servo laser beam are tracked using the reference layer TR-bl in the bulk layer formed on the bulk type recording medium 1. The optical axis correction amount (value of the position detection signal ps-sh by the position sensor 31) required for each rotation angle of the bulk type recording medium 1 is sampled in a state where the directions are forcibly matched. . At the time of recording, the spot position deviation is corrected by driving and controlling the beam shifter 14B based on the information of the necessary correction amount for each rotation angle sampled in this way.
By adopting such a correction operation, it is possible to omit the configuration for detecting the skew amount and the lens shift amount of the objective lens in correcting the spot position deviation, and to correct the information recording position by the recording / reproducing laser beam. Can be performed with higher accuracy based on the actually sampled correction amount.
Since the configuration for detecting the skew / lens shift amount is not required, the apparatus can be reduced in size and cost.

  In addition, if the information recording position can be corrected with higher accuracy, the track pitch on the reference surface Ref (the distance between the position guides in the radial direction) can be reduced accordingly, resulting in an increase in recording capacity. Is achieved.

Further, since the track pitch can be reduced, the access time can be shortened accordingly. That is, when the track pitch is wide, it takes a long time to search the recorded data string. However, according to the present embodiment, this is alleviated and the access time is shortened.

<6. Modification>

Although the embodiments of the present invention have been described above, the present invention should not be limited to the specific examples described above.
For example, in the above description, the case where the reference track TR-bl in the bulk layer 5 is formed only for one layer position is illustrated, but as shown in FIG. Can also be provided for a plurality of layer positions.
In the example of FIG. 9, the reference track TR-bl is provided for each information recording layer position L. As shown in the figure, the reference track TR-bl formed at the information recording layer position L1 is the reference track TR-bl_L1. Similarly, the other reference tracks TR-bl are set as a reference track TR-bl_L2, a reference track TR-bl_L3, a reference track TR-bl_L4, and a reference track TR-bl_L5 according to the layer position L to be formed.

In this case, the correction amount sampling operation is performed for each information recording layer position L. Specifically, the same processing as that shown in FIG. 7 is performed using the reference track TR-bl_Ln formed at the information recording layer position Ln to be recorded, thereby correcting each layer position L. Sampling quantity (creating table information).
As a result, when performing multilayer recording on the bulk layer 5, it is possible to correct information recording position deviation based on an appropriate correction amount corresponding to each information recording layer position L.

  It should be noted that in performing information recording position correction using an appropriate correction amount corresponding to each information recording layer position L as described above, it is always necessary to provide the reference track TR-bl at each information recording layer position L. There is no. For example, when multi-layer recording of three or more layers is performed on the bulk layer 5, at least the information recording layer position (L1) serving as the uppermost layer and the information recording layer position (L5) serving as the lowermost layer are used as the reference track TR-bl. Then, the interpolation amount for each rotation angle obtained by the sampling operation at the uppermost layer and the correction amount for each rotation angle obtained by the sampling operation at the lowermost layer are linearly interpolated, and the remaining A method of obtaining a correction amount for each rotation angle used at each information recording layer position L can also be adopted. That is, in this case, at the time of recording at the information recording layer position L where the reference track TR-bl is not formed, correction of the spot position deviation is performed using the information of the correction amount for each rotation angle thus obtained by linear interpolation. Is what you do.

  Alternatively, the bulk layer 5 is divided into an area for each of a plurality of information recording layer positions L in the depth direction (referred to as a layer direction area), and the reference track is only for a predetermined information recording layer position L in each layer direction area. A method of forming TR-bl can also be adopted. That is, the correction amount for each rotation angle obtained by the sampling operation using the reference track TR-bl formed at the predetermined information recording layer position L in a certain layer direction area is used as the other information in the layer direction area. It is shared at the recording layer position L.

Also, a plurality of reference tracks TR-bl can be provided in the radial direction as shown in FIG.
FIG. 10 shows an example in which the reference track TR-bl is formed (the reference track TR-rf is set) at three locations, the inner circumference, the middle circumference, and the outer circumference. As shown in the figure, the reference track TR-bl1 (TR-rf1), the reference track TR-bl2 (TR-rf2), and the reference track TR-bl3 (TR-rf3) are sequentially set from the inner peripheral side.
Here, when the radial position is different, the optimum correction amount (offset, gain) may be different. Therefore, if the correction amount is sampled for each radial area, the optimum correction amount is used for each area even when the optimum correction amount differs depending on the radial position. Spot position deviation correction can be realized, and the correction accuracy can be improved.
As a specific method, also in this case, based on the same idea as in the depth direction described with reference to FIG. 9, the radial area is set so that one reference track TR-bl is included in one radial area. (In the example shown in the figure, the area is divided into inner, middle, and outer areas), and for each radial area, for each rotation angle obtained by the sampling operation using the reference track TR-bl in that area. A technique of using a correction amount can be employed.
Alternatively, for example, the reference track TR-bl is formed only at two locations of a predetermined radial position on the inner peripheral side and a predetermined radial position on the outer peripheral side such as the innermost peripheral position and the outermost peripheral position, and the sampling operation at these two positions It is also possible to adopt a method of calculating and using the correction amount for each rotation angle at each radial position by linearly interpolating the correction amount for each rotation angle obtained by performing the above.

  In the description so far, the case where the correction amount is sampled at every rotation angle of 1 ° has been exemplified. However, for example, the correction amount can be sampled at every other predetermined rotation angle such as 2 ° or 5 °.

  In the description so far, the case where the rotation angle information recorded on the optical disk recording medium (reference surface) is used for sampling the correction amount for each rotation angle is exemplified. For example, a spindle for rotating the optical disk recording medium A rotation angle detection unit that detects the rotation angle of the motor may be provided, and the correction amount for each rotation angle may be sampled based on the rotation angle information detected by the rotation angle detection unit.

  In the description so far, the case where the shift lens 14A is shifted by the beam shifter 14B to correct the spot position deviation (adjustment of the optical axis) is exemplified. However, the spot between the recording / reproducing laser beam and the servo laser beam is exemplified. The positional deviation can be corrected by other means such as a galvanometer mirror.

In the above description, the correction of the spot position deviation has been exemplified by adjusting the optical axis on the recording / reproducing laser beam side. However, it is also possible to adjust the optical axis on the servo laser beam side. Spot position deviation can be corrected. That is, in this case, the objective lens 20 is moved by the amount of shift of the optical axis of the servo laser beam, thereby correcting the spot position of the recording / reproducing laser beam.
Note that when the spot position deviation is corrected by the optical axis adjustment unit that adjusts the optical axis on the servo laser beam side in this way, in order to forcibly match each spot position during sampling operation, The optical axis on the servo laser light side based on the reflected light of the recording / reproducing laser light while making the servo laser light follow the reference track TR-rf by tracking servo control of the objective lens 20 based on the reflected light of the working laser light By performing the tracking servo control of the adjustment unit, the recording / reproducing laser beam follows the reference track TR-bl.
As can be understood from the above description, in the present invention, the optical axis adjustment unit for correcting the spot position shift changes the relative positional relationship between the optical axes of the recording / reproducing laser beam and the servo laser beam. Any device may be used as long as it can be configured.

  In the description so far, the case where the movement amount of the shift lens 14A (the correction amount of the spot position deviation) is detected by using the position sensor 31 is exemplified, but the movement amount of the shift lens 14A is detected by, for example, the beam shifter 14B. A method of detecting based on the driving signal can also be adopted, and the method is not particularly limited to one method.

In the above description, the case where the present invention is applied to the case where information recording is performed on the bulk type recording medium 1 has been exemplified. However, the present invention is not limited to the recording on the multilayer recording medium 50 as shown in FIG. The present invention can also be suitably applied when performing the above.
11, the multilayer recording medium 50 is the same as the bulk type recording medium 1 shown in FIG. 1 in that the cover layer 2, the selective reflection film 3, and the intermediate layer 4 are formed in order from the upper layer side. In this case, instead of the bulk layer 5, a recording layer having a layer structure in which a semitransparent recording film 51 and an intermediate layer 4 are repeatedly laminated a predetermined number of times as shown in the figure is laminated. As shown in the figure, the translucent recording film 51 formed in the lowermost layer is laminated on the substrate 52. Note that a total reflection recording film can be used as the recording film formed in the lowermost layer.
Here, it should be noted that the translucent recording film 51 is not provided with a position guide accompanying the formation of grooves or pit rows. That is, in this multilayer recording medium 50 as well, the spiral or concentric circular position guide is formed only for one layer position as the reference plane Ref.
Therefore, in this case, a reference track by mark formation is formed in advance on the required translucent recording film 51 in the recording layer at a position having the same radial position as the predetermined track set on the reference surface Ref. The correction amount is sampled using the reference track.

In the recording layer of the multilayer recording medium 50, since the semitransparent recording film 51 that functions as a reflective film is formed, focus control using the reflected light of the recording / reproducing laser beam is performed even during recording. It can be carried out.
That is, at the time of recording in this case, the focus servo control for the recording / reproducing laser beam is performed by driving the objective lens 20 based on the reflected light of the recording / reproducing laser beam, so that the translucent recording to be recorded is performed. This is performed so that the film 51 is focused.
On the other hand, the tracking servo control of the recording / reproducing laser beam at the time of recording is also performed using the servo laser beam. That is, even in this case, the tracking servo control at the time of recording is performed by driving the objective lens 20 based on the reflected light from the reference surface Ref of the servo laser light so that the focal position of the servo laser light is the reference surface Ref. This is done so as to follow the guide groove.

At the time of reproduction, also in this case, tracking servo control of the recording / reproducing laser beam can be performed based on the already recorded mark train. Further, as understood from the above description, the focus servo control of the recording / reproducing laser beam is also performed by using the reflected light from the target translucent recording film 51 (information recording layer L) even during reproduction. It can be carried out.
That is, in this case, the servo control during reproduction is performed by the same method as in the embodiment. That is, the focus servo control of the recording / reproducing laser beam at the time of reproduction is based on the reflected light of the recording / reproducing laser beam so that the recording / reproducing servo beam is focused on the target information recording layer L. The tracking servo control of the recording / reproducing laser beam is performed based on the reflected light of the recording / reproducing laser beam so that the focal position of the recording / reproducing servo beam follows the recorded mark row. This is done by driving the objective lens 20.

  For confirmation, even when such a multilayer recording medium 50 is used, the spot position deviation correction method and the correction amount sampling method itself are the same as those described above.

  In the description so far, the case where the position guide is formed on the optical disc recording medium is exemplified by the provision of the concave-convex cross-sectional shape pattern such as a groove or a pit row. However, the position guide included in the optical disc recording medium according to the present invention. May be formed by other methods such as recording a mark row.

  In the description so far, the case where the reference surface Ref on which the position guide is formed is formed on the upper layer side than the recording layer is exemplified. However, the reference surface Ref is formed on the lower layer side than the recording layer. In addition, the present invention can be preferably applied.

  In the description so far, the dichroic prism 19 is provided to receive the reflected light of the recording / reproducing laser beam and the servo laser beam independently on the apparatus side, and the difference in wavelength of each light is used. However, instead of this, for example, a configuration for performing spectroscopy using a difference in polarization direction such as p-polarized light / s-polarized light is adopted, and thus the spectral is performed by other methods. You can also.

  In the above description, the case where the present invention is applied to a recording / reproducing apparatus that performs both recording and reproduction with respect to an optical disc recording medium has been exemplified. However, the present invention is a recording-only unit that can only record on an optical disc recording medium. The present invention can also be suitably applied to an apparatus (recording apparatus).

  1 Bulk type recording medium, 2 cover layer, 3 selective reflection film, Ref reference surface, 4 intermediate layer, 5 bulk layer, L mark formation layer position (information recording layer position), TR-rf reference surface reference track, TR- bl Bulk layer reference track, 10 recording / reproducing device, 11 recording / reproducing laser, 12,25 collimation lens, 13,26 polarization beam splitter, 14A shift lens, 14B beam shifter (lens drive unit), 15 movable lens, 16 lens drive Part, 17 mirror, 18, 27 1/4 wavelength plate, 19 dichroic prism, 20 objective lens, 21 biaxial actuator, 22, 28 condenser lens, 23 recording / reproducing light receiving part, 24 servo laser, 29 servo light Light receiving unit, 31 position sensor, 32 recording processing unit, 33 recording / playback matrix circuit, 34 reproduction processing unit, 35 Servo light recording / reproducing circuit, 36 Servo light matrix circuit, 37 Position information detector, 38 Servo light servo circuit, 39 Driver, 40 Controller, 50 Multi-layer recording medium, 51 Translucent recording film, 52 Substrate

Claims (10)

The track as a position guide has a reference surface having a reflective film formed in a spiral shape or concentric shape, a recording layer on which information recording is performed by mark formation according to light irradiation, and in the recording layer, An optical drive device that performs at least recording on an optical disc recording medium on which a reference track is formed at the same radial position as a predetermined track on the reference surface,
First light for recording information on the recording layer and second light for performing position control based on the position guide formed on the reference surface are incident, and the first light and An objective lens for irradiating the optical disk recording medium with both of the second light;
A tracking mechanism that drives the objective lens in a tracking direction that is parallel to the radial direction of the optical disk recording medium;
An optical axis adjustment unit that changes a relative positional relationship between the optical axes of the first light and the second light incident on the objective lens;
A first tracking servo signal generator that generates a first tracking servo signal from a tracking error signal obtained by receiving reflected light from the optical disc recording medium of the first light;
A second tracking servo signal generator for generating a second tracking servo signal from a tracking error signal obtained by receiving reflected light from the optical disc recording medium of the second light,
A correction amount detection unit that detects the correction amount of the optical axis by the optical axis adjustment unit;
A control unit,
The control unit
The tracking servo control for the second light based on the second tracking servo signal by the tracking mechanism causes the spot position of the second light to follow the predetermined track on the reference plane, and the light The axis adjustment unit causes tracking servo control for the first light based on the first tracking servo signal to be executed so that the spot position of the first light follows the reference track in the recording layer. In the state, the correction amount of the optical axis detected by the correction amount detector is sampled for each rotation angle of the optical disc recording medium,
An optical drive device that instructs the optical axis adjustment unit to execute the correction of the optical axis by instructing the correction amount sampled at each rotation angle. In the optical disc recording medium, the position guide is formed along with the recording of absolute position information including at least information indicating the rotational angle position on the optical disc recording medium.
A position information detector for detecting the absolute position information recorded on the optical disc recording medium;
The optical drive apparatus according to claim 1, wherein the control unit samples the correction amount for each rotation angle based on absolute position information detected by the position information detection unit. The optical axis adjustment unit is
A beam shifter configured to translate the optical axis of the first light incident on the objective lens by driving a shift lens;
The optical drive apparatus according to claim 1, wherein the correction amount detection unit detects a movement amount of the shift lens by the beam shifter. The optical drive device according to claim 3, wherein the correction amount detection unit includes a position sensor that detects a position of the shift lens. The optical recording medium according to claim 1, wherein recording is performed on the optical disc recording medium having the bulk recording layer in which mark recording is selectively performed at a desired layer position in the depth direction without a reflective film. Drive device. In the optical disc recording medium, the reference track is formed at a plurality of layer positions in the recording layer,
The optical drive apparatus according to claim 1, wherein the control unit performs sampling of the correction amount for each layer position based on a reference track formed at the plurality of layer positions. In the recording layer, three or more layer positions are set as mark recording positions, and the reference track is formed with respect to at least two layer positions of the uppermost layer and the lowermost layer. ,
The control unit
The correction amount is sampled based on the reference track formed for at least two layer positions of the uppermost layer and the lowermost layer, and the correction amount sampled at those layer positions is generated by linear interpolation. The optical drive apparatus according to claim 6, wherein the optical axis adjustment unit is controlled using the corrected amount so that spot position deviation correction is performed at a layer position where the reference track is not formed. In the recording layer, three or more layer positions are set as the layer positions to be subjected to mark recording, and the reference track is formed for each of the layer positions.
The control unit
The optical drive device according to claim 6, wherein the correction amount is sampled for each layer position based on a reference track formed at each layer position. In the optical disc recording medium, the reference track is formed at a plurality of radial positions in the recording layer,
The optical drive apparatus according to claim 1, wherein the control unit performs sampling of the correction amount for each of the plurality of radial positions based on reference tracks formed at the plurality of radial positions. The track as a position guide has a reference surface having a reflective film formed in a spiral shape or concentric shape, a recording layer on which information recording is performed by mark formation according to light irradiation, and in the recording layer, An optical drive device that performs at least recording on an optical disk recording medium on which a reference track is formed at the same radial position as a predetermined track on the reference surface, and a first light for performing information recording on the recording layer And second light for performing position control based on the position guide formed on the reference surface, and both the first light and the second light are incident on the optical disc recording medium. An irradiating objective lens; a tracking mechanism that drives the objective lens in a tracking direction that is parallel to a radial direction of the optical disk recording medium; An optical axis adjusting unit that changes a relative positional relationship between the optical axes of the first light and the second light incident on the lens; and a reflected light of the first light from the optical disk recording medium. A first tracking servo signal generator for generating a first tracking servo signal from the tracking error signal obtained in this manner, and a tracking error signal obtained by receiving the reflected light of the second light from the optical disc recording medium. Spot position deviation in an optical drive device comprising a second tracking servo signal generation unit that generates a second tracking servo signal and a correction amount detection unit that detects a correction amount of the optical axis by the optical axis adjustment unit A correction method,
The tracking servo control for the second light based on the second tracking servo signal by the tracking mechanism causes the spot position of the second light to follow the predetermined track on the reference plane, and the light The axis adjustment unit causes tracking servo control for the first light based on the first tracking servo signal to be executed so that the spot position of the first light follows the reference track in the recording layer. In a state, a sampling procedure for sampling the correction amount of the optical axis detected by the correction amount detector for each rotation angle of the optical disk recording medium,
And a correction control procedure for instructing the optical axis adjustment unit to execute the correction of the optical axis by instructing the correction amount sampled at each rotation angle.