JP2011192350A - Recording device, reproducing device, recording method, and reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase a surface recording density in an optical recording for forming a hole mark on a bulk layer. <P>SOLUTION: A multi-valued recording is performed based on size of the hole mark by forming a recording mark column by a plurality of kinds of hole marks having different sizes in the surface direction and thickness direction on the bulk layer on the basis of the recording information. An information value is recorded also by a space length between the hole marks. At the reproduction, an information value detection for the amplitude level of a reflected light quantity signal corresponding to the size and an information value detection based on the space length are performed, and reproduction data are created from these detections. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a recording apparatus, a reproducing apparatus, a recording method, and a reproducing method for a bulk type optical recording medium that records information using hole marks.

JP 2008-176902 A

An optical disc system such as a CD (Compact Disc), a DVD (Digital Versatile Disc), or a Blu-ray Disc (registered trademark) is a microscopic element formed on one side of a disc in a non-contact manner like an objective lens of a microscope. Reading changes in reflectivity.
As is well known, the size of the light spot on the disk is given by approximately λ / NA (λ: wavelength of illumination light, NA: numerical aperture), and the resolution is also proportional to this value.

Also known are a method of forming a plurality of recording layers in the depth direction of the disc and a method of increasing the capacity of a single disc by recording in a multilayer form in a bulk type (volume type) recording medium. ing.
In particular, as a promising method for increasing the capacity of an optical recording medium, there is a method in which dozens of recording layers are formed in a thickness direction in a bulk recording material. A method of forming and recording information has been proposed.
When recording in a bulk-type recording medium, a plastic with a refractive index of approximately 1.5 is irradiated with high-density light, and holes filled with a gas with a refractive index of approximately 1.0 are formed. Recording and playback as a mark.

Incidentally, mark position recording and mark edge recording are methods for recording information on the recording layer of an optical recording medium.
Mark position recording is a method for detecting position information of a recording mark, and mark edge recording is a method for detecting a front end portion and a rear end portion of a recording mark.
The number of bits per unit length is larger in the latter, that is, mark edge recording allows higher density recording. However, the condition necessary for forming the recording mark is only the control of the position in the mark position recording, whereas the control of the length of the recording mark in addition to the position is very important in the mark edge recording.

Considering a method of forming hole marks in the bulk layer of the above bulk type optical recording medium, mark edge recording is a relatively difficult recording method. This is because it is known that the position control of the hole is very difficult while the position control is easy at the time of formation.
The reason why it is difficult to control the length is that there is no internal structure in the bulk material that can control the shape of mark formation such as a groove. Furthermore, since the degree of freedom of the shape is also in the thickness direction when the holes are formed, it is considered that changing the length also changes the width and height of the holes.

For this reason, regarding hole mark recording, it is difficult to increase the density by mark edge recording.
Accordingly, an object of the present invention is to provide a recording / reproducing system capable of improving the surface recording density relatively easily when recording with a hole mark in a bulk type recording medium.

The recording apparatus of the present invention includes an optical pickup that irradiates a bulk layer of a bulk type optical recording medium based on a laser drive signal, forms hole marks, and records information, and based on the recorded information. A recording processing unit that generates a laser drive signal for forming a plurality of types of hole marks having different sizes in the surface direction and the thickness direction of the recording layer in the bulk layer, and supplies the laser driving signal to the optical pickup.
Further, the laser drive signal generated by the recording processing unit is a laser drive signal for forming two or more types of spaces as a space between the hole mark and the hole mark based on the recording information.
The laser driving signal generated by the recording processing unit is a laser driving signal for forming hole marks of various sizes in a predetermined unit length region in the bulk layer.
The recording processing unit generates a laser drive signal that causes the hole mark to be formed at a substantially central portion of the unit length region.
The recording processing unit generates a laser drive signal for forming a plurality of types of hole marks having different sizes in the surface direction and the thickness direction by variably setting the pulse level and / or the pulse period.

The reproducing apparatus of the present invention emits laser light to a recording mark row formed of a plurality of types of hole marks having different sizes in the surface direction and thickness direction formed in the bulk layer of the bulk type optical recording medium based on the recording information. An optical pickup that irradiates and obtains a reflected light amount signal, and detects the amplitude level of the reflected light amount signal, thereby detecting a first information value (hole mark) recorded according to the size in the surface direction and thickness direction of the hole mark. And a reproduction unit that generates reproduction data using the first information value.
Further, the recording mark row is further formed with a space of two or more types as a space between the hole mark and the hole mark based on the recorded information. A second information value (information value by mark position recording) corresponding to the determined space length is detected, and reproduction data is generated using the first and second information values. For example, the reproducing unit detects the peak of the reflected light amount signal and determines the space length from the peak-to-peak time.

The recording method of the present invention is a method for recording information on a bulk-type optical recording medium. Based on the recording information, the recording method includes a plurality of types having different sizes in the surface direction and the thickness direction of the recording layer in the bulk layer of the bulk-type recording medium. A laser drive signal for forming a hole mark is generated, and laser irradiation is performed in the bulk layer by an optical pickup based on the laser drive signal.
The reproducing method of the present invention is an optical information reproducing method for a bulk type optical recording medium in which recording mark arrays of a plurality of types of hole marks having different sizes in the surface direction and thickness direction are formed in a bulk layer based on recorded information. Information recorded according to the size of the hole mark in the surface direction and thickness direction is obtained by irradiating the recording mark row with a laser to obtain a reflected light amount signal and detecting the amplitude level of the reflected light amount signal. A value is detected, and reproduction data is generated using the information value.

In the case of hole recording on a bulk material, it is possible to form dozens of recording layers in the thickness direction, but the control of the mark length is very difficult. Improvement is difficult. On the other hand, the hole mark varies in its hole size (size in the surface direction and thickness direction) according to the energy of the irradiated laser beam, and the amplitude corresponding to the hole size as light quantity information during reproduction. It was confirmed that a signal suitable for multi-level detection can be obtained.
Therefore, the multi-level recording is performed according to the hole size to improve the surface recording density.
Furthermore, the recording position control is relatively easy in hole mark recording. Therefore, mark position recording is also used for hole marks by multi-value recording, and information values can be obtained also by the space length between marks. That is, by performing information recording in both multi-value recording and mark position recording, the surface recording density is further improved.

  According to the present invention, in the recording / reproducing operation for forming the hole mark on the bulk type recording medium, the multi-value recording by the size of the hole mark is performed, and the multi-value recording and the mark position recording are used in combination. Thus, the surface recording density can be improved relatively easily.

It is explanatory drawing of the recording medium of embodiment of this invention. It is explanatory drawing of the servo control about the recording medium of embodiment. It is explanatory drawing of the recording / reproducing apparatus with respect to the recording medium of embodiment. It is explanatory drawing of the multi-value recording by the hole mark of embodiment. It is explanatory drawing of the multi-value recording by the hole mark in the unit length area | region of embodiment. It is explanatory drawing of combined use of multi-value recording and mark position recording of an embodiment. 1 is a block diagram of a recording apparatus configuration according to an embodiment. It is explanatory drawing of operation | movement of the pulsed light drive signal generation circuit of embodiment. It is a block diagram of the reproducing | regenerating apparatus structure of embodiment. It is explanatory drawing of operation | movement of the amplitude detection circuit of embodiment. It is explanatory drawing of the write strategy of embodiment. It is explanatory drawing of the write strategy and reproduction signal of embodiment. It is explanatory drawing of the reproduction signal of the conventional optical recording mark.

Hereinafter, a recording / reproducing apparatus according to an embodiment of the recording apparatus and the reproducing apparatus of the present invention will be described in the following order. The recording / reproducing apparatus according to the embodiment records information by forming hole marks in the bulk layer of a bulk type optical recording medium, and reproduces a record mark row by the hole marks.

<1. Structure of optical recording medium used in embodiment>
<2. Servo control during recording and playback>
<3. Configuration of recording / reproducing apparatus>
<4. Combined use of multi-value recording and mark position recording of hole marks>
<5. Recording operation>
<6. Playback operation>

<1. Structure of optical recording medium used in embodiment>

FIG. 1 shows a cross-sectional structure diagram of a bulk type optical recording medium (recording medium 1) on which the recording / reproducing apparatus of the embodiment performs recording and reproduction.
The recording medium 1 shown in FIG. 1 is a disk-shaped optical recording medium, and the recording medium 1 that is rotationally driven is irradiated with laser light to perform mark recording (information recording). Also, the reproduction of the recorded information is performed by irradiating the recording medium 1 that is rotationally driven with a laser beam.
The optical recording medium refers to a recording medium on which recorded information is reproduced by light irradiation.
In this example, so-called voids are formed as recording marks.
In the void recording method, for example, a laser beam is irradiated with a relatively high power to a bulk layer made of a recording material such as a photopolymerization type photopolymer, and voids are recorded in the bulk layer. It is. The hole portion thus formed becomes a portion having a refractive index different from that of the other portion in the bulk layer, and the light reflectance is increased at the boundary portion. Therefore, the hole portion functions as a recording mark, thereby realizing information recording by forming the hole mark.

In FIG. 1, a recording medium 1 is a so-called bulk type optical recording medium, and a cover layer 2, a selective reflection film 3, an intermediate layer 4, and a bulk layer 5 are formed in order from the upper layer side as shown.
Here, the “upper layer side” in this specification refers to the upper layer side when a surface on which a laser beam from a reproducing apparatus side described later is incident is an upper surface.
Further, in this specification, the terms “depth direction” or “thickness direction” are used, and the “depth direction” and “thickness direction” are the top and bottom of FIG. 1 according to the definition of “upper layer side”. The direction coincides with the direction (that is, the direction parallel to the incident direction of the laser beam from the reproducing apparatus side).

In the recording medium 1, the cover layer 2 is made of, for example, a resin such as polycarbonate or acrylic, and as shown in the drawing, a cross-sectional shape of irregularities accompanying the formation of a guide groove for guiding the recording / reproducing position on the lower surface side. Is given. When viewed in the disk plane direction, the guide groove 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 a groove, the groove is periodically meandered to form position information (absolute position information: for example, rotation angle information or radial position information) based on the meandering period information. It can be performed.
The cover layer 2 is generated by 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, in the bulk recording method, tracking or tracking based on the guide groove as described above is performed separately from recording light for performing mark recording on the bulk layer 5 as a recording layer (hereinafter also referred to as first laser light). Servo light (also referred to as second laser light) for obtaining a focus error signal is separately irradiated.
At this time, if the servo light reaches the bulk layer 5, the mark recording in the bulk layer 5 may be adversely affected. For this reason, there is a need for a reflective film having selectivity that reflects servo light and transmits recording light.
In the bulk recording method, laser light having different wavelengths is used for recording light and servo light. In order to cope with this, as the selective reflection film 3, a selective reflection film having wavelength selectivity is used, in which light in the same wavelength band as that of the servo 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 formed via 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), a material suitable for the void recording method may be employed. For example, a plastic material is used.

For the bulk layer 5, information recording is performed by forming a hole mark by sequentially focusing the laser beam on each predetermined position in the depth direction of the bulk layer 5.
Accordingly, a plurality of mark forming layers (information recording layers) L are formed in the bulk layer 5 in the recording medium 1 that has been recorded. As shown in the figure as information recording layers L0 to L (n), a large number (n + 1) of information recording layers are formed.

Although the thickness size and the like of the bulk layer 5 are not definitive, for example, when it is considered to irradiate blue laser light (wavelength 405 nm) with an optical system with NA of 0.85, from the disk surface (the surface of the cover layer 2) It is appropriate to form the information recording layer at a position of 50 μm to 300 μm in the depth direction. This is a range in consideration of spherical aberration correction.
FIG. 1 shows an example in which the information recording layer is formed at a position of 70 μm to 260 μm from the disk surface.
Of course, under the condition that the position range in the depth direction is the same, a larger number of information recording layers can be formed as the layer interval is reduced.

In each information recording layer, recording with a hole mark is performed in a state where tracking servo is performed using a guide groove formed in the cover layer 2. Therefore, the hole mark array formed in the information recording layer is formed in a spiral shape when viewed in the disk plane direction.

<2. Servo control during recording and playback>

Next, servo control during recording / reproduction for the recording medium 1 as a bulk type optical recording medium will be described with reference to FIG.
The recording medium 1 is irradiated with a second laser beam LZ2 as a servo beam having a wavelength different from that of the first laser beam LZ1 for forming a recording mark and reproducing information from the recording mark.
As will be described later with reference to FIG. 3, the first laser light LZ1 and the second laser light LZ2 are applied to the recording medium 1 through a common objective lens (objective lens 21 in FIG. 3).

Here, as shown in FIG. 1, the bulk layer 5 in the recording medium 1 is different from a multi-layer disc such as an optical disc such as a DVD or a Blu-ray disc. The reflective surface which has is not formed.
For this reason, at the time of recording in which the mark is not yet formed, the focus servo and tracking servo for the first laser beam LZ1 cannot be performed using the reflected light of the first laser beam LZ1 itself.
From this point, at the time of recording on the recording medium 1, both the tracking servo and the focus servo for the first laser light LZ1 are performed using the reflected light of the second laser light LZ2 as the servo light.

  Specifically, regarding the focus servo of the first laser beam LZ1 at the time of recording, first, the focus mechanism for the first laser beam LZ1 that can independently change only the focus position of the first laser beam LZ1 (see FIG. 3 and the lens driving unit 19). Then, the first laser beam focusing mechanism is controlled based on the offset of as shown in FIG. 2 with reference to the selective reflection film 3 (guide groove forming surface).

Here, as described above, the first laser beam LZ1 and the second laser beam LZ2 are applied to the recording medium 1 through a common objective lens. The focus servo of the second laser light LZ2 is performed by controlling the objective lens using the reflected light from the selective reflection film 3 of the second laser light LZ2.
Thus, the first laser beam LZ1 and the second laser beam LZ2 are irradiated through the common objective lens, and the focus servo of the second laser beam LZ2 is reflected from the selective reflection film 3 of the second laser beam LZ2. This is done by controlling the objective lens based on the light. Thereby, the focusing position of the first laser beam LZ1 basically follows the selective reflection film 3. That is, in other words, the focus servo of the objective lens based on the reflected light of the second laser beam LZ2 from the selective reflection film 3 follows the surface variation of the recording medium 1 with respect to the in-focus position of the first laser beam LZ1. The function is given.
After that, the focus position of the first laser beam LZ1 is offset by the value of the offset of by the first laser beam focusing mechanism as described above. Thereby, the in-focus position of the first laser beam LZ1 can be made to follow a required depth position in the bulk layer 5.

In the drawing, an example of each offset of corresponding to the case where the information recording layers L0 to L (n) are set in the bulk layer 5 is shown. That is, the offset of-L0 corresponding to the layer position of the information recording layer L0, the offset of-L1 corresponding to the layer position of the information recording layer L1,... The offset of− corresponding to the layer position of the information recording layer L (n) The case where L (n) is set is shown.
By driving the focus mechanism for the first laser using the value of these offsets of, the mark formation position (recording position) in the depth direction is changed from the layer position as the information recording layer L0 to the information recording layer L. The layer position as (n) can be selected as appropriate.

  Further, regarding the tracking servo for the first laser beam LZ1 at the time of recording, the point that the first laser beam LZ1 and the second laser beam LZ2 are irradiated through a common objective lens as described above, This is realized by performing tracking servo of the objective lens using the reflected light of the second laser light LZ2 from the selective reflection film 3.

On the other hand, since the information recording layer L is formed in the bulk layer 5 during reproduction, the reflected light of the first laser beam LZ1 from the information recording layer L is obtained. Can do. Therefore, during reproduction, focus servo for the first laser beam LZ1 is performed using the reflected light of the first laser beam LZ1 itself.
Specifically, focus servo for the first laser beam LZ1 during reproduction is performed by controlling the focus mechanism for the first laser beam described above based on the reflected light of the first laser beam LZ1.
Further, the tracking servo of the first laser beam LZ1 at the time of reproduction is realized by performing the tracking servo of the objective lens based on the reflected light of the second laser beam LZ2.

Here, even during reproduction, the focus of the second laser beam LZ2 targeting the guide groove forming surface (guide groove) for reading out the absolute position information recorded on the guide groove forming surface as the selective reflection film 3 Servo and tracking servo are performed.
That is, during reproduction, as in recording, the position of the objective lens is controlled by the focus servo of the second laser beam LZ2 targeting the guide groove forming surface (guide groove) based on the reflected light of the second laser beam LZ2.・ Tracking servo will be performed.

Note that the tracking servo of the first laser beam LZ1 during reproduction may be performed by controlling the objective lens based on the reflected light of the first laser beam LZ1 with respect to the recording mark row of hole marks.
Also, address information can be read from the record mark string at least during reproduction after seek.
For this reason, it is conceivable that the second laser beam LZ2 is not used during reproduction.

<3. Configuration of recording / reproducing apparatus>

FIG. 3 shows a configuration of the recording / reproducing apparatus 10 of the present embodiment that performs recording / reproduction with respect to the recording medium 1 of FIG.
First, the recording medium 1 loaded in the recording / reproducing apparatus 10 is rotationally driven by a spindle motor (SPM) 39 in the drawing.
The recording / reproducing apparatus 10 is provided with an optical pickup OP that irradiates the first laser beam LZ1 and the second laser beam LZ2 to the recording medium 1 that is rotationally driven in this manner.

In the optical pickup OP, a first laser 11 that is a light source of the first laser beam LZ1 for performing information recording by forming hole marks and reproducing information recorded by the hole marks, and servo light A second laser 25 that is a light source of the second laser light LZ2 is provided.
As described above, the first laser beam LZ1 and the second laser beam LZ2 have different wavelengths. In the case of this example, the wavelength of the first laser beam LZ1 is about 405 nm (so-called blue-violet laser beam), and the wavelength of the second laser beam LZ2 is about 660 nm (red laser beam).

In addition, an objective lens 21 serving as an output end of the first laser beam LZ1 and the second laser beam LZ2 to the recording medium 1 is provided in the optical pickup OP. The NA of the objective lens 21 is 0.85.
Furthermore, the first photo detector 24 for receiving the reflected light from the recording medium 1 of the first laser beam LZ1, and the second photo detector 30 for receiving the reflected light of the second laser beam LZ2 from the recording medium 1. Is provided.

In addition, in the optical pickup OP, the first laser light LZ1 emitted from the first laser 11 is guided to the objective lens 21, and the reflected light of the first laser light LZ1 from the recording medium 1 incident on the objective lens 21 is obtained. An optical system for guiding the light to the first photodetector 24 is formed.
In addition, in the optical pickup OP, in addition, the second laser light LZ2 emitted from the second laser 25 is guided to the objective lens 21 and the second laser light LZ2 from the recording medium 1 incident on the objective lens 21 is transmitted. An optical system that guides the reflected light to the second photodetector 30 is formed.

First, the optical system for the first laser beam LZ1 will be described.
The first laser beam LZ1 emitted from the first laser 11 is first converted into parallel light via the collimation lens 12, and then its optical axis is bent by 90 degrees by the mirror 13 so that the polarization beam splitter 14 Is incident on. The polarization beam splitter 14 is configured to transmit the first laser light LZ1 emitted from the first laser 11 and entering through the mirror 13 in this way.

The first laser beam LZ1 that has passed through the polarization beam splitter 14 passes through the liquid crystal element 15 and the quarter-wave plate 16.
The liquid crystal element 15 is provided to correct so-called off-axis aberrations such as coma and astigmatism.

The first laser light LZ1 that has passed through the quarter-wave plate 16 is incident on an expander including the lens 17 and the lens 18. In this expander, the lens 17 on the side close to the first laser 11 as a light source is a fixed lens, and the lens 18 on the side far from the first laser 11 is a movable lens. The lens drive unit 19 drives the lens 18 in a direction parallel to the optical axis of the first laser beam, thereby performing independent focus control on the first laser beam LZ1.
The expander lens driving unit 19 performs focus control of the first laser beam based on the output signal from the first laser focus servo circuit 37.
The lens drive unit 19 offsets the in-focus position of the first laser beam LZ1 based on an instruction from the controller 38 during recording, and performs focus control of the first laser beam LZ1 based on a servo control signal during reproduction.

  The first laser beam LZ1 that has passed through the expander is incident on the dichroic mirror 20. The dichroic mirror 20 is configured to transmit light in the same wavelength band as the first laser light LZ1 and reflect light having other wavelengths. Accordingly, the first laser beam LZ1 incident as described above is transmitted through the dichroic mirror 20.

The first laser beam LZ1 transmitted through the dichroic mirror 20 is irradiated to the recording medium 1 through the objective lens 21.
With respect to the objective lens 21, the objective lens 21 can be displaced in a focus direction (a direction in which the objective lens 21 is moved toward and away from the recording medium 1) and a tracking direction (a direction perpendicular to the focus direction: a radial direction of the recording medium 1) A two-axis mechanism 22 is provided for holding.
The biaxial mechanism 22 displaces the objective lens 21 in the focus direction and the tracking direction by applying drive currents to the focus coil and tracking coil from the focus servo circuit 36 and tracking servo circuit 35 for the second laser, respectively.

During reproduction, in response to the irradiation of the first laser light LZ1 to the recording medium 1 as described above, the recording medium 1 (particularly the information recording layer L to be reproduced in the bulk layer 5) The reflected light of one laser beam is obtained. The reflected light of the first laser light LZ1 obtained in this way is guided to the dichroic mirror 20 through the objective lens 21 and passes through the dichroic mirror 20.
The reflected light of the first laser beam LZ1 that has passed through the dichroic mirror 20 passes through the lens 18 and the lens 17 constituting the expander, and then enters the polarization beam splitter 14 through the quarter-wave plate 16 and the liquid crystal element 15. To do.

  Thus, the reflected light (return light) of the first laser light LZ1 incident on the polarization beam splitter 14 is reflected from the first laser 11 side by the action of the quarter-wave plate 16 and the action of reflection on the recording medium 1. The direction of polarization of the first laser beam LZ1 incident on the polarization beam splitter 14 is 90 degrees different from that of the forward beam. As a result, the reflected light of the first laser light LZ1 incident as described above is reflected by the polarization beam splitter 14.

  The reflected light of the first laser light LZ1 reflected by the polarizing beam splitter 14 is guided to the condensing lens 23 side in the drawing. The condensing lens 23 condenses the reflected light of the first laser beam LZ1 on the detection surface of the first photodetector 24.

Next, an optical system for the second laser beam LZ2 will be described.
The second laser light LZ2 emitted from the second laser 25 is converted into parallel light through the collimation lens 26 and then enters the polarization beam splitter 27. The polarization beam splitter 27 is configured to transmit the forward light of the second laser light LZ2 that has entered through the collimation lens 26 in this way.

The second laser light LZ2 that has passed through the polarization beam splitter 27 is incident on the dichroic mirror 20 via the quarter-wave plate.
As described above, the dichroic mirror 20 is configured to transmit light having the same wavelength band as that of the first laser light LZ1 and reflect light having other wavelengths. Accordingly, the second laser beam LZ2 is reflected by the dichroic mirror 20, and is irradiated onto the recording medium 1 through the objective lens 21 as shown in the figure.

In addition, the reflected light of the second laser light LZ2 (reflected light from the selective reflection film 3) obtained in response to the irradiation of the recording medium 1 with the second laser light LZ2 passes through the objective lens 21, After being reflected by the dichroic mirror 20 and passing through the quarter-wave plate 28, the light enters the polarization beam splitter 27.
Similar to the case of the first laser beam LZ1, the reflected light (return light) of the second laser beam LZ2 incident from the recording medium 1 side is reflected by the action of the quarter wavelength plate 28 and the reflection on the recording medium 1. Due to the action, the direction of polarization differs from that of forward light by 90 degrees. Accordingly, the return light of the second laser beam LZ2 is reflected by the polarization beam splitter 27.
The reflected backward light of the second laser beam LZ2 is condensed on the detection surface of the second photodetector 30 via the condenser lens 29.

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

  The recording / reproducing apparatus 10 includes a recording processing unit 31, a first laser matrix circuit 32, a reproduction processing unit 33, a second laser matrix circuit 34, a tracking servo circuit 35, a second laser focus servo circuit 36, and a first laser. A laser focus servo circuit 37 and a controller 38 are provided.

First, data (recording data) to be recorded on the recording medium 1 is input to the recording processing unit 31. The recording processing unit 31 adds binary values “0” and “1” that are actually recorded on the recording medium 1 by adding an error correction code to the input recording data or performing predetermined recording modulation encoding. A modulated data sequence that is a data sequence is obtained.
In response to an instruction from the controller 38, the recording processing unit 31 performs light emission driving of the first laser 11 based on the recording modulation data string generated in this way.

The first laser matrix circuit 32 includes a current-voltage conversion circuit, a matrix calculation / amplification circuit, and the like corresponding to output currents from a plurality of light receiving elements as the first photodetector 24, and generates necessary signals by matrix calculation processing. To do.
Specifically, a high frequency signal (hereinafter referred to as a reproduction signal RF) corresponding to a reproduction signal obtained by reproducing the above-described recording modulation data string, and a focus error signal FE for focus servo control are generated.
In this example, there are two types of focus error signal FE, one based on the reflected light of the first laser light and the other based on the reflected light of the second laser light. Hereinafter, the focus error signal FE generated by the first laser matrix circuit 32 is referred to as a focus error signal FE-1 in order to distinguish the two.

The reproduction signal RF generated by the first laser matrix circuit 32 is supplied to the reproduction processing unit 33.
The focus error signal FE-1 is supplied to the first laser focus servo circuit 37.

  The reproduction processing unit 33 reproduces the reproduction signal RF generated by the first laser matrix circuit 32, such as decoding by multi-value detection and mark position detection described later, and error correction processing, etc. To obtain reproduced data obtained by reproducing the recorded data.

The first laser focus servo circuit 37 generates a focus servo signal based on the focus error signal FE-1, and drives and controls the lens driving unit 19 based on the focus servo signal, so that the first laser light LZ1 is generated. Focus servo control is performed.
The focus servo control of the first laser beam LZ1 by driving the lens driving unit 19 based on the reflected light of the first laser beam LZ1 is performed during reproduction.
At the time of recording, the first laser focus servo circuit 37 drives and controls the lens drive unit 19 so as to give the required offset of described with reference to FIG.
Further, the first laser focus servo circuit 37 performs an interlayer jump operation between the information recording layers L formed on the recording medium 1 and pulls in the focus servo to the required information recording surface L in accordance with an instruction from the controller 38 during reproduction. The lens drive unit 19 is driven and controlled so as to be performed.

On the other hand, with respect to the second laser light LZ2 side, the second laser matrix circuit 34 includes a current-voltage conversion circuit, a matrix calculation / amplification circuit, and the like corresponding to output currents from a plurality of light receiving elements as the second photodetector 30. Then, necessary signals are generated by matrix calculation processing.
Specifically, the second laser matrix circuit 34 generates a focus error signal FE-2 and a tracking error signal TE for servo control.
The focus error signal FE-2 is supplied to the second laser focus servo circuit 36, and the tracking error signal TE is supplied to the tracking servo circuit 35.

The second laser focus servo circuit 36 generates a focus servo signal based on the focus error signal FE-2, and drives the focus coil of the biaxial mechanism 22 based on the focus servo signal. Thereby, focus servo control by driving the objective lens 21 is performed. As described above, the focus servo control of the objective lens 21 is performed based on the reflected light of the second laser beam LZ2 at the time of recording / reproducing.
In response to an instruction from the controller 38, the second laser focus servo circuit 36 causes the focus servo to be drawn into the selective reflection film 3 (guide groove forming surface) formed on the recording medium 1 so as to focus the coil. Drive.

  The tracking servo circuit 35 generates a tracking servo signal based on the tracking error signal TE from the second laser matrix circuit 34 and drives the tracking coil of the biaxial mechanism 22 based on the tracking servo signal. As described above, the tracking servo control of the objective lens 21 is performed based on the reflected light of the second laser beam LZ2 at the time of recording / reproducing.

The controller 38 is composed of a microcomputer including a memory (storage device) such as a CPU (Central Processing Unit) and ROM (Read Only Memory), and executes control and processing according to a program stored in the ROM, for example. Thus, the entire control of the recording / reproducing apparatus 10 is performed.
At the time of recording, the controller 38 controls the focus position of the first laser beam (recording position in the depth direction) based on the offset value set corresponding to each layer position described in FIG. Selection). That is, the controller 38 selects the recording position in the depth direction by driving the lens driving unit 19 based on the value of the offset of set corresponding to the layer position to be recorded.
The value of the offset of is stored in a ROM, flash memory or the like in the controller 38. By setting the values of the offsets of-L0 to of-L (n), the positions of the information recording layers L0 to L (n) in the recording medium 1 are set. In other words, the layer spacing of each of the information recording layers L0 to L (n) is also determined.

As described above, the tracking servo control during recording is performed based on the reflected light of the second laser beam LZ2. Therefore, the controller 38 instructs the tracking servo circuit 35 to execute tracking servo control based on the tracking error signal TE during recording.
During recording, the controller 38 instructs the second laser focus servo circuit 38 to execute focus servo control (focus servo control for the objective lens 21) based on the focus error signal FE-2.

On the other hand, at the time of reproduction, the controller 38 instructs the first laser focus servo circuit 37 to focus the first laser beam LZ1 on the information recording layer L on which data to be reproduced is recorded. That is, the focus servo control for the information recording layer L is executed with respect to the first laser beam LZ1.
The controller 38 also executes tracking servo control based on the tracking error signal TE by the tracking servo circuit 35 even during reproduction.
Further, at the time of reproduction, the controller 38 executes focus servo control (focus servo control of the objective lens 21) based on the focus error signal FE-2 by the second laser focus servo circuit 38.

  Although not illustrated, the absolute position information recorded on the selective reflection film 3 (guide groove forming surface) is read based on the reflected light of the second laser light LZ2. Therefore, in practice, the second laser matrix circuit 34 generates a reproduction signal for the signal recorded on the guide groove forming surface. For example, a sum signal as an RF signal is generated when information recording is performed using a pit row, and a push-pull signal is generated when information recording is performed using a wobbling groove. In addition, a position information detection unit that detects absolute position information based on a reproduction signal for such a recording signal is provided.

Further, as described above, the tracking servo of the first laser beam LZ1 during reproduction is performed by controlling the objective lens based on the reflected light of the first laser beam LZ1 with respect to the recording mark row of the hole marks. You may do it.
In this case, the tracking error signal TE is generated by the first laser matrix circuit 32 and is supplied to the tracking servo circuit 35 to drive the biaxial mechanism 22 so that the tracking servo control by the objective lens 21 is performed. That's fine.
Further, the configuration of the recording / reproducing apparatus 10 shown in FIG. 3 is an example, and various configuration examples are conceivable, for example, the configuration of the optical system in the optical pickup OP, the configuration of the servo control system, and the like.

<4. Combined use of multi-value recording and mark position recording of hole marks>

The recording / reproducing apparatus 10 of this embodiment performs multi-value recording as hole mark recording. In the following, multi-value recording using hole marks, and combined use of multi-value recording and mark position recording will be described.

First, for comparison, a recording mark on a conventional optical disc, for example, a DVD or a Blu-ray disc will be described with reference to FIG.
FIG. 13A schematically shows a case where the mark MK is recorded on the recording “surface” of the conventional optical disc by, for example, the phase change method or the dye change method, and FIG. The reproduction signal is shown.
FIG. 13A shows a state where lands LN and grooves GV are formed on the recording surface of the optical disc, and marks MK are recorded on the grooves GV by laser light irradiation.
When a mark LS of the mark MK is irradiated with a reproduction laser beam spot LS and a reproduction signal is generated from the reflected light, the result is as shown in FIG.
That is, in the conventional optical recording / reproduction, the reproduction signal level is constant when the length of the mark MK exceeds a certain value, and the output level increases or decreases at the timing according to the length of the mark MK. For example, a recording mark MK on a Blu-ray disc has a variable length of 2T to 8T (T is a channel clock period), but the reproduction signal amplitude corresponding to the 4T mark or more is almost the maximum output level.

On the other hand, the reproduction signal level by the hole mark of the present embodiment is schematically shown in FIG.
4A and 4B show a hole mark VM recorded and reproduced by the laser beam LZ1 in a sectional view and a top view.
In this example, the hole mark VM to be formed is a plurality of types having different sizes in the surface direction (radial direction) and thickness direction of the recording layer (bulk layer 5) as shown in the figure. That is, the hole mark VM has various types of holes.

  As a reproduction signal RF obtained when reproducing a recording mark row with such a hole mark VM, the amplitude level is in accordance with the size (hole volume) of the hole mark VM as shown in FIG. Change. The reproduction signal waveform changes in a similar shape according to the hole marks VM of different sizes.

  As described above, in the recording / reproduction of the hole mark VM, the amplitude of the reproduction signal RF changes according to the size of the hole mark VM, and each signal waveform has a similar shape. It has been found that the recording / reproducing of the hole mark VM is suitable for multi-value recording.

FIG. 5 schematically shows that N values are expressed by the size of the hole mark VM in the recording / reproducing of the hole mark VM. 5A and 5B are a cross-sectional view and a top view of the hole mark VM, and FIG. 5C shows the waveform of the reproduction signal RF for the hole mark VM.
First, a unit length area UA is defined.
One hole mark VM of N types of sizes is recorded in the unit length area UA.
In the drawing, an example is shown in which the first size, second size, third size... K size... N size hole mark VM is formed in the unit length area UA in order from the right. Yes.

When such a recording mark row is irradiated with the first laser beam LZ1 and the reproduction signal RF is obtained from the reflected light, the amplitude is as shown in FIG.
Corresponding to the first size hole mark VM, an amplitude having a peak value of level LV1 is obtained.
Corresponding to the second size hole mark VM, an amplitude having a peak value of level LV2 is obtained.
Corresponding to the hole mark VM of the third size, an amplitude having a peak value of level LV3 is obtained.
Corresponding to the k-th size hole mark VM, an amplitude having a peak value of level LVk is obtained.
Corresponding to the Nth size hole mark VM, an amplitude having a peak value of level LVN is obtained.

Thus, by obtaining different amplitude levels depending on the size of the hole mark VM, multi-value recording as N values can be realized by the hole mark VM.
By this multi-value recording, the surface recording density in recording / reproducing with the hole mark VM is improved.

Further, in the present embodiment, this multi-value recording and mark position recording are combined.
This realizes information recording / reproduction that achieves a recording density equal to or higher than that without using mark edge recording.

FIG. 6 shows an example of a recording method using both multi-value recording and mark position recording.
6A and 6B are a cross-sectional view and a top view of the hole mark VM, and FIG. 6C shows the waveform of the reproduction signal RF for the hole mark VM. FIG. 6D shows binary data as reproduction data to be reproduced.
The unit length area UA is set to 3.5T.

As shown in FIGS. 6A and 6B, hole marks VM having different sizes are formed in the bulk layer 5 as recording data strings. Each hole mark VM is formed in a unit length area UA of 3.5T. Each hole mark VM is formed such that its center of gravity is located approximately at the center in the 3.5T unit length area UA.
The multi-value by the hole mark VM is expressed by marks of various sizes in which the amplitude level of the reproduction signal RF is 2M to 8M. That is, multi-level recording is performed in 7 stages.
Hereinafter, a mark with an amplitude level of 2M is referred to as a “2M mark”. Similarly, a mark with an amplitude level of 2M is called a “3M mark”... A mark with an amplitude level of 8M is called an “8M mark”.

  Two or more types of spaces are formed between the hole marks VM and the hole marks VM, that is, as spaces. Here, it is assumed that a space having a length from 2T space to 8T space is formed. That is, it has seven types of space lengths.

The space length is defined by the space between the hole mark VM and the center of gravity of the hole mark VM.
The first hole mark VM in FIG. 6 is a 2M mark, and the second hole mark VM is a 5M mark. Here, the center of gravity of each hole mark VM in the planar direction is substantially the center in the unit length area UA of 3.5T.
As shown in FIG. 6C, the centroid position of the first 2M mark is separated from the centroid position of the second 5M mark by 10.5T. The space length can be considered as a section obtained by removing half of the unit length area UA of the first 2M mark and half of the unit length area UA of the second 5M mark from 10.5T. That is,
10.5T- (3.5T / 2)-(3.5T / 2) = 10.5T-3.5T = 7T
It is. That is, the space length between the first 2M mark and the second 5M mark is 7T.
In the same way, the subsequent space lengths are 2T space, 5T space, 3T space, and 8T space in the figure.

That is, the hole mark VM is formed in the unit length area UA of 3.5T, and the space length between the hole marks VM is set to a plurality of types.
This is to perform mark position recording in which multiple values are recorded according to the size of the hole mark VM, and the recording position of the hole mark VM is controlled to form another type of space length.
FIG. 6 shows an example in which the space length is 7-modulated from 2T to 8T and the mark output level is 7-modulated from 2M to 8M. The reason why the unit length area UA that forms the recording mark in this case is set to 3.5T is that it is an average length considering the appearance frequency of the space length from 2T to 8T.

The reproduction signal RF when reproducing the recording mark string of FIGS. 6 (a) and 6 (b) is as shown in FIG. 6 (c), and the binary data of FIG. 6 (d) is decoded from this reproduction signal waveform. .
First, the bit string “11” is decoded from the amplitude level of the 2M mark. Next, a bit string “0000000” is decoded from the 7T space. Further, binary data is decoded from 5M mark to “11111”, 2T space to “00”, 3M mark to “111”, 5T space to “00000”, and so on.

With the recording method as shown in FIG. 6, high density recording equivalent to the (1, 7) RLL random signal can be realized relatively easily in the method of recording the hole mark VM on the bulk type optical recording medium. That is, the recording position of the hole mark VM can be easily controlled by the emission timing of the first laser beam LZ1. Therefore, it is not difficult to control the space length.
In addition, a multivalue (for example, 7 values) can be expressed by the size of the hole mark VM. For this reason, high-density recording is possible without using mark edge recording by modulating the space length and the mark size.
In particular, in the case of hole recording on a bulk material, although it is possible to form dozens of recording layers in the thickness direction, it is very difficult to control the mark length. It was difficult to improve. However, it is possible to easily improve the surface recording density by using a combination of mark position recording and multi-valued controllable techniques.

<5. Recording operation>

The configuration and operation of the recording processing unit 31 for performing the recording as described above will be described.
As described with reference to FIG. 3, the recording data is subjected to predetermined modulation and write strategy in the recording processing unit 31 to generate a laser drive signal. The first laser 11 is driven to emit light by the laser drive signal.
Here, the first laser is assumed to be a pulse light source, and the recording processing unit 31 will be described as giving a pulsed light drive signal to the first laser 11 as a laser drive signal.

FIG. 7 shows the configuration of the recording processing unit 31.
The recording processing unit 31 includes a recording original signal generation circuit 61 and a pulsed light drive signal generation circuit 62. The pulsed light drive signal from the pulsed light drive signal generation circuit 62 is supplied to the first laser 11 in the optical pickup OP.
2 is rotated by a disk rotation drive circuit 80.
The system clock is supplied to the recording original signal generation circuit 61 and the pulsed light drive signal generation circuit 62.
The channel clock is supplied to the pulse light drive signal generation circuit 62 and the disk rotation drive circuit 80.

The recording original signal generating circuit 61 generates an original recording signal by adding an error correction code to the input recording data (binary data) or performing predetermined recording modulation encoding. For example, RLL (1-7) modulation is performed.
Based on the generated recording original signal, the pulsed light drive signal generation circuit 62 generates a pulsed light drive signal as a laser drive signal.

The processing operation of the pulsed light drive signal generation circuit 62 will be described as procedures S1 to S6 in FIG.
(Procedure S1)
A binary data string as a recording original signal is input to the pulsed light drive signal generation circuit 62.
(Procedure S2)
The pulsed light drive signal generation circuit 62 determines a continuous period of “0” and “1” for the input binary data string.
Speaking in accordance with the example of FIG. 6 described above, there are “00” to “00000000”, that is, 2T to 8T, as the space period expressed by the binary data string. The mark values expressed by the binary data string include “11” to “11111111”, that is, 2T (2M) to 8T (8M).

(Procedure S3)
According to the mark values of 2T (2M) to 8T (8M) recognized from “1” of the recording original signal, the pulse light for forming the hole mark VM of each size from 2M mark to 8M mark Determine the ON time and intensity.
For this determination, for example, the conversion table of FIG.
In the conversion table, ON times and pulse light intensities corresponding to 2T (2M) to 8T (8M) of the recording original signal are set.
The ON time shown in the figure is an example when the unit length area UA is set to 3.5T. The pulse light intensity is a relative value when the peak intensity during 4T and 5T recording is 1.
Using this conversion table, the pulse light ON time and pulse light intensity are selected in accordance with each of mark values 2T (2M) to 8T (8M) appearing in the original recording signal. Then, a signal is generated so that the recording mark time is 3.5T in total.

(Procedure S4)
A space time corresponding to a space length of 2T to 8T recognized from “0” of the recording original signal is generated.
(Procedure S5)
A pulsed light drive signal is generated based on the pulsed light signal generated in step S3 and the space time generated in step S4.
(Procedure S6)
The generated pulsed light drive signal is output to the first laser 11.

An example of the pulsed light drive signal generated by the above procedure will be described with reference to FIG.
Here, a case where a recording data string as a 5M mark, 2T space, 2M mark, 8T space, and 8M mark is recorded is taken as an example.

FIG. 11A shows pulsed light before modulation. That is, the laser power of pulsed light when the first laser 11 emits light without modulation. This pulsed light is pulsed light having a predetermined repetition frequency fp. For example, the width of one pulsed light is an optical output of several psec.
FIG. 11B shows the system clock.
FIG. 11C shows the original recording signal. This H level period length of the recording original signal corresponds to a period of “1”, that is, the mark values of 2T (2M) to 8T (8M). The L level period length corresponds to a space length of 2T to 8T.
FIG. 11D shows a channel clock. The channel clock period is 1T. If the channel clock is fc and the system clock is fs, fs> fc. The recording original signal is transferred from the recording original signal generation circuit 61 to the pulsed light drive signal generation circuit 62 based on the system clock, but the system clock fs is set high so that it can be transferred in a short time.

FIG. 11E shows a pulsed light drive signal generated by the procedure shown in FIG.
First, in the 3.5T period corresponding to the unit length area UA, an intensity and ON time pulse corresponding to the 5M mark is generated.
Following this 3.5T period, the pulsed light drive signal is at the L level during the 2T period corresponding to the 2T space.
In the next 3.5T period, a pulse of intensity and ON time corresponding to the 2M mark is formed.
Following the 3.5T period, the pulsed light drive signal is at the L level for the 8T period corresponding to the 8T space.
In the next 3.5T period, an intensity and ON time pulse corresponding to the 8M mark is formed.

  For example, such a pulsed light drive signal is generated and supplied to the first laser 11. That is, the mark portion pulse is generated based on the conversion table as described in step S3 of FIG.

  The first laser 11 performs the laser output of FIG. 11A when there is no modulation, but the output period (ON time) and the laser intensity are controlled by the pulsed light drive signal, so that the first laser 11 of FIG. Such pulse laser output is performed.

FIG. 12A shows the pulsed light output after the same modulation as that in FIG.
As the first laser 11 performs such laser output, a void mark VM is formed in the bulk layer 5 of the recording medium 1 as shown in FIG. That is, the recording mark string is the multi-value recording and mark position recording described in FIG.

<6. Playback operation>

Next, the operation of the reproduction processing unit 33 at the time of reproduction with respect to the record mark string recorded as described above will be described.
FIG. 9 shows the configuration of the reproduction processing unit 33.
The reproduction processing unit 33 includes a peak detection circuit 71, a PLL circuit 72, an amplitude detection circuit 73, and a binary data generation circuit 74.

As described with reference to FIG. 3, the return light of the first laser beam LZ1 during reproduction is received by the first photodetector 24, and a current corresponding to the amount of received light is obtained. The first laser matrix circuit 32 performs current-voltage conversion, matrix calculation, equalization processing, and the like to generate a reproduction signal RF as a light amount signal and supplies the reproduction signal RF to the reproduction processing unit 33.
For example, at the time of reproduction with respect to the recording data string in which the hole mark VM is recorded as shown in FIG. 12B, a reproduction signal RF as shown in FIG. 12C is supplied to the reproduction processing unit 33.
In the reproduction processing unit 33, the reproduction signal RF is input to the peak detection circuit 71 and the amplitude detection circuit 73.

The peak detection circuit 71 detects the peak timing of the reproduction signal RF by, for example, differentiating the reproduction signal RF, and inputs the peak timing signal to the PLL circuit 72.
The PLL circuit 72 generates a reproduction clock using the peak timing signal. The PLL circuit 72 supplies the reproduction clock and the peak timing signal to the amplitude detection circuit 73. The PLL circuit 72 also supplies the reproduction clock to the binary data generation circuit 74.

The amplitude detection circuit 73 performs amplitude detection and peak-to-peak time detection on the input reproduction signal RF.
FIG. 10 shows the processing of the amplitude detection circuit 73 as steps S11 to S15.
(Procedure S10)
A reproduction clock and a peak timing signal are supplied from the PLL circuit 72.
(Procedure S11)
A reproduction signal RF is input from the first laser matrix circuit 32.
(Procedure S12)
The amplitude detection circuit 73 designates the peak timing of the amplitude of the reproduction signal RF based on the peak timing signal.

(Procedure S13)
The amplitude detection circuit 73 evaluates the amplitude value of the reproduction signal RF at the peak timing. That is, it is determined which peak level is 2M to 8M in FIG.
(Procedure S14)
The amplitude detection circuit 73 measures the time between the previous peak timing and the current peak timing based on the reproduction clock. When the space length is 2T to 8T as in the example of FIG. 6, the peak-to-peak time is 5.5T to 11.5T. It is determined which time is between these peaks.
(Procedure S15)
The amplitude level determined in step S13 and the peak-to-peak time determined in step S14 are output to the binary data generation circuit 74.

The binary data generation circuit 74 decodes the binary data based on the amplitude level and the peak-to-peak time detected by the amplitude detection circuit 73.
That is, “11” to “11111111” are decoded according to 2M to 8M determined as the amplitude level.
Further, the space lengths 2T to 8T are determined based on the peak-to-peak time −3.5T, and “00” to “00000000” are decoded.
These are combined to generate binary data as shown in FIG. 6D, for example. That is, reproduction data is generated.

  By the operation of the reproduction processing unit 33 as described above, appropriate data reproduction is performed with respect to the recording mark string by multi-value recording and mark position recording.

The present invention is not limited to the above embodiment, and various modifications can be considered.
Although FIG. 6 shows an example of 7 modulation with the size of the hole mark VM and 7 modulation with mark position recording, it is a matter of course that each is not limited to 7 modulation. The present invention includes at least two modulations in the size of the hole mark VM, that is, recording / reproduction by the hole mark VM having two or more types of sizes. Further, the present invention includes recording / reproducing at least 2 modulations in the size of the hole mark VM and at least 2 modulations (that is, two or more types of space lengths) in mark position recording.
In the recording / reproducing operation example of the present embodiment, a series of binary data is recorded and reproduced by mark position recording in multi-value recording. However, a data string by multi-value recording and a data string by mark position recording are parallel. An example in which recording / reproduction is automatically performed is also conceivable.

In addition, the recording / reproducing apparatus 10 as an example of the recording apparatus and the reproducing apparatus of the present invention has been described.
In the case of a recording-only apparatus, the configuration shown in FIG. In the case of a reproduction-only device, the configuration shown in FIG.
It goes without saying that various examples of the configuration of the optical pickup OP and the configuration of the servo control system in FIG. 3 are assumed.

  1 recording medium, 2 cover layer, 3 selective reflection film, 4 intermediate layer, 5 bulk layer, L0 to L (n) information recording layer, VM hole mark, 31 recording processing unit, 33 reproduction processing unit, 61 recording original signal Generation circuit, 62 pulse light drive signal generation circuit, 71 peak detection circuit, 72 PLL circuit, 73 amplitude detection circuit, 74 binary data generation circuit

Claims (10)

Based on the laser drive signal, an optical pickup that irradiates the bulk layer of the bulk type optical recording medium with laser light, forms hole marks, and records information;
Based on the recording information, a recording processing unit that generates a laser driving signal for forming a plurality of types of hole marks having different sizes in the surface direction and the thickness direction of the recording layer in the bulk layer, and supplies the laser driving signal to the optical pickup;
Recording device.   2. The laser driving signal generated by the recording processing unit is a laser driving signal for forming two or more types of spaces as a space between a hole mark and a hole mark based on recording information. The recording device described in 1.   The recording apparatus according to claim 2, wherein the laser driving signal generated by the recording processing unit is a laser driving signal for forming a hole mark of each size in a predetermined unit length region in the bulk layer.   The recording apparatus according to claim 3, wherein the recording processing unit generates a laser drive signal that causes a hole mark to be formed at a substantially central portion of the unit length region.   The recording apparatus according to claim 3, wherein the recording processing unit generates a laser drive signal for forming a plurality of types of hole marks having different sizes in the surface direction and the thickness direction by variable setting of a pulse level and / or a pulse period. . Based on the recording information, a laser beam is irradiated to a recording mark row formed of a plurality of types of hole marks having different sizes in the surface direction and thickness direction formed in the bulk layer of the bulk type optical recording medium, and a reflected light amount signal is obtained. With an optical pickup to get,
By detecting the amplitude level of the reflected light amount signal, the first information value recorded according to the size in the surface direction and the thickness direction of the hole mark is detected, and the reproduction data is detected using the first information value. A playback unit to generate,
A playback device. In the recording mark row, two or more types of spaces are formed as a space between the hole mark and the hole mark based on the recorded information.
The said reproduction | regeneration part further detects the 2nd information value according to the space length discriminate | determined from the said reflected light amount signal, The reproduction | regeneration data are produced | generated using the said 1st, 2nd information value. Playback device.   The reproducing apparatus according to claim 7, wherein the reproducing unit detects a peak of the reflected light amount signal and determines a space length from a peak-to-peak time. As a method for recording information on a bulk type optical recording medium,
Based on the recording information, a laser driving signal for generating a plurality of types of hole marks having different sizes in the surface direction and the thickness direction of the recording layer in the bulk layer of the bulk type recording medium is generated, and based on the laser driving signal A recording method in which laser irradiation is performed in the bulk layer by an optical pickup.   As a method of reproducing information for a bulk type optical recording medium in which a plurality of types of hole marks having different sizes in the surface direction and the thickness direction based on the recorded information are formed in the bulk layer, the above-mentioned recording mark array is formed by an optical pickup. The reflected light quantity signal is obtained by irradiating the laser beam, and the amplitude level of the reflected light quantity signal is detected to detect the information value recorded by the size of the hole mark in the surface direction and the thickness direction. A playback method for generating playback data using values.

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