JP2011141936A - Optical drive device, and method for adjusting recording parameter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve proper recording parameter adjustment with respect to a multilayer optical recording medium. <P>SOLUTION: For example, with respect to recording laser power, recording can not be performed by laser power which is regarded as optimized, when a position where another recording layer is in a recorded state is recorded with power adjusted when the other recording layer is in an unrecorded state, or conversely when a position where another recording layer is in an unrecorded state is recorded with power adjusted when the other recording layer is in a recorded state. A recording parameter is thereby adjusted and controlled, based on reflected light information previously detected before recording motion by for a region before recording as a target. The recording parameter is then adjusted by taking the influence of whether the other recording layer is in the recorded state or in the unrecorded state into consideration, and as a result recording quality is stabilized irrespective of whether the other layer is in the recorded or unrecorded state. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical drive apparatus that records and reproduces information by irradiating an optical recording medium with laser light, and a recording parameter adjusting method thereof, and more particularly to recording on a multilayer optical recording medium having a plurality of recording layers. It is suitable for application.

JP 2005-259212 A JP 2005-293689 A JP 2008-77714 A JP 2006-120281 A

  In an optical drive device that records and reproduces recordable optical recording media such as write-once type optical discs and rewritable type optical discs, various recording parameters are used to prevent deterioration of recording quality due to media characteristic variations and temperature changes. Have been made to make adjustments. In particular, with respect to the recording laser power, so-called OPC (Optimum Power Control) is performed, and various methods have been proposed.

The OPC operation is generally performed prior to the recording operation on the optical disc. For example, test data is recorded in a predetermined test area set on the disk while changing the laser power. Then, the recorded portion is reproduced, and the evaluation value of the reproduction signal is measured. For example, β value, modulation degree, jitter, asymmetry, symbol error rate, etc. are used as evaluation values.
Based on these evaluation values, it is determined at which laser power the recording signal quality is good, and the optimum laser power is determined.

In some cases, the OPC operation is performed during the recording operation.
Patent Documents 1 and 2 disclose techniques related to so-called running OPC.
Patent Documents 3 and 4 disclose techniques related to walking OPC.

  Here, when recording a series of data, the weaking OPC (hereinafter also referred to as WOPC) interrupts the sequential recording operation at a predetermined timing, for example, every predetermined section, and the recording signal of the recorded section is recorded. The quality is evaluated by a predetermined evaluation value (for example, the β value), and the recording laser power is adjusted so that the evaluation value matches a predetermined target value. By sequentially adjusting the recording laser power in this way, the recording quality can be stabilized over the entire area of the optical disk.

For confirmation, FIG. 10 shows a schematic diagram of a conventional WOPC.
When performing WOPC, a WOPC section with a predetermined section length, such as every 1 mm radius, is set. Thus, for example, a section (write section in the figure) where a series of data designated by a recording command is to be recorded can be expressed as being divided into a plurality of WOPC sections as shown in the figure.
In each WOPC section, a section in which a recorded signal is reproduced when measuring a β value as an evaluation value is determined in advance, and this is shown as an evaluation value measurement section in the drawing. This evaluation value measurement section is preferably set at the end of the WOPC section as shown in the figure in consideration of shortening of the seek time.

In the conventional WOPC, first, the WOPC section is recorded (<1>), and then the evaluation value measurement section is reproduced, so that the top level (Top Lv) and bottom level (Bottom) of the envelope of the reproduction signal (RF signal) are reproduced. After measuring Lv) (<2>), a β value as an evaluation value is calculated (<3>).
As is well known, the β value represents the asymmetry of the reproduction signal,

β = (Top Lv + Bottom Lv) / (Top Lv−Bottom Lv)

Is calculated by
Then, the recording laser power is adjusted so that the β value calculated in this way becomes a predetermined target value (β-TG) (<4>).
The β value becomes large when the recording laser power is larger than the optimum value, and conversely becomes smaller when the recording laser power is smaller than the optimum value. Therefore, the laser power adjustment reduces the laser power when the calculated β value is larger than the target value β-TG, and conversely increases the laser power when the β value is smaller than the target value β-TG. To do so.

  On the other hand, in recent years, as an optical disc, a recording layer having a multilayered recording layer has been proposed in order to increase the information recording capacity. The point to be considered in such a multilayer optical disk is the influence due to the recording / non-recording of other recording layers.

For example, when recording parameter adjustment such as WOPC described above is performed, an evaluation value for evaluating the recording signal quality is measured. This evaluation value is recorded / unrecorded by other recording layers. Different values may be obtained depending on the type of recording. In particular, regarding the recording laser power, if the other recording layer (front layer) has already been recorded, the amount of light reaching the target recording layer is reduced accordingly, so that the other recording layer has been recorded. Therefore, the optimum laser power differs depending on whether or not recording is performed.
Therefore, for example, when recording the position where the other recording layer is in the recording state with the parameter adjusted when the other recording layer is in the unrecorded state, or conversely, the parameter adjusted when the other recording layer is in the recording state. When recording a position where the other recording layer is in an unrecorded state, it is not possible to perform recording with an optimum parameter, and as a result, it becomes difficult to stabilize the recording quality. .

FIG. 11 is a diagram for explaining the influence given by the recording / non-recording of other recording layers as described above. The β value and error rate obtained when the other recording layers are recorded / unrecorded, respectively. The relationship of (iMLSE) is shown. Note that iMLSE is an evaluation value of an error rate correlation used in a reproduction system that employs a bit detection method based on PRML (Partial Response Maximum Likelihood).
In this figure, the set value of the target value β-TG is also illustrated.

  As can be seen by comparing the β value (solid line) when there is no recording in the other recording layer shown in the figure and the β value (broken line) when there is recording, when the other recording layer is recording, If the recording laser power is not increased more than when the other recording layers are not recording, the equivalent β value cannot be obtained. In other words, in order to obtain the same recording quality, when the other recording layer is recorded, a larger power is required than when there is no recording.

As described above, in WOPC, the recording laser power is adjusted so that the β value coincides with the target value β-TG. From the relationship of the β value with and without the recording, the recording value is not recorded. The recording laser power adjusted in the state (corresponding to 14 mW in the figure) does not coincide with the optimum laser power when recording is present (corresponding to 16 mW in the figure).
In other words, this means that when recording the position where the other recording layer is in the recording state with the laser power adjusted when the other recording layer is in the unrecorded state, or conversely, when the other recording layer is in the recording state. When recording a position where the other recording layer is in an unrecorded state with the adjusted laser power, the recording cannot be performed with the optimum laser power.
Furthermore, due to such a phenomenon, there is a relatively large difference in recording quality between a section where other recording layers are recorded and a section where no recording is recorded, and as a result, the recording quality is not stable. End up.

  For example, when recording on a multi-layer optical recording medium in this way, the optimum recording parameters may differ depending on whether the other recording layer is recorded or not recorded. As a result, the recording quality is stable. It is very difficult to record.

In view of the above problems, the present invention is configured as follows as an optical drive device.
That is, a recording unit for recording information by irradiating the optical recording medium with laser light is provided.
The apparatus further includes a reflected light detection unit that detects reflected light of the laser light irradiated to the optical recording medium.
In addition, the reflected light detection operation is executed in advance on the pre-recording area of the optical recording medium before the recording operation is performed, and the recording parameter adjustment control in the recording unit is performed based on the reflected light information detected thereby. The control part to perform is provided.

  As described above, if the recording parameter adjustment control is performed based on the reflected light information detected in advance before the recording operation is performed on the pre-recording area, the optical recording medium is a multilayer optical recording medium. In some cases, it is possible to perform recording parameter adjustment in consideration of the effect of recording / non-recording of other recording layers.

As described above, according to the present invention, recording parameters can be adjusted in consideration of the influence of recording / non-recording on other recording layers during recording on a multilayer optical recording medium.
As described above, the recording parameters can be adjusted in consideration of the influence of the recording / non-recording of other recording layers, so that the recording quality of the multilayer optical recording medium can be stabilized.

1 is a cross-sectional structure diagram of an optical recording medium targeted in an embodiment. It is the figure which showed the internal structure of the optical drive apparatus as a 1st example of embodiment. It is a figure for demonstrating the outline | summary of WOPC as embodiment. It is a figure for demonstrating the relationship between the evaluation value Vopc calculated in a 1st example, and recording laser power. It is a flowchart for demonstrating the procedure of the specific process which should be performed corresponding to the time of initial stage OPC in a 1st example. It is a flowchart for demonstrating the procedure of the specific process which should be performed corresponding to the time of WOPC in a 1st example. It is the figure which showed the internal structure of the optical drive apparatus as a 2nd example of embodiment. It is a flowchart for demonstrating the procedure of the specific process which should be performed corresponding to the time of initial stage OPC in a 2nd example. It is a flowchart for demonstrating the procedure of the concrete process which should be performed corresponding to the time of WOPC in a 2nd example. It is a figure for demonstrating conventional WOPC. It is a figure for demonstrating the influence given by the distinction of recording / unrecording of another recording layer.

Embodiments of the present invention will be described below. Here, as an example of the optical drive apparatus of the present invention, a disk drive apparatus that performs recording / reproduction on a recordable optical disk is taken as an example, and the WOPC (Walking Optimum Power Control) operation will be described.
The description will be given in the following order.

<1. Example of target optical recording medium>
<2. Configuration example of optical drive device>
<3. WOPC as an embodiment>
[3-1. WOPC as a first example]
[3-2. WOPC as a second example]
<4. Modification>

<1. Example of target optical recording medium>

FIG. 1 is a cross-sectional structure diagram of an optical disk recording medium to be recorded and reproduced in the present embodiment. Hereinafter, an optical disc recording medium to be recorded and reproduced in the embodiment is referred to as an optical disc D.
First, in FIG. 1, the arrow in the figure indicates the irradiation direction of the laser beam.
The optical disk D includes a cover layer CV, a translucent recording film R-hlf, a repeating layer of an intermediate layer Mid, a recording film R, and a substrate BS in order from the upper layer side when the surface on which laser light is incident is the upper surface. Is formed.
The optical disc D of this example is a four-layer optical disc recording medium, and the number of repetitions of the translucent recording film R-hlf and the intermediate layer Mid is 3 as shown in the figure.

The translucent recording film R-hlf and the recording film R include, for example, a phase change film, a dye change film, and the like, and a recording mark is formed at a position where the laser beam with the recording power is condensed. The recording film R located on the lowermost layer side has a total reflection film, and each translucent recording film R-hlf formed on the upper layer side of the recording film R transmits a part of incident laser light (partially A semi-reflective film that reflects) is formed.
As shown in the drawing, each translucent recording film R-hlf and recording film R is provided with a cross-sectional shape of irregularities accompanying the formation of a groove (track).

<2. Configuration example of optical drive device>

FIG. 2 shows an internal configuration of the disk drive device 1 that performs recording and reproduction for the optical disk D shown in FIG.
In FIG. 2, an optical disk D is loaded on a turntable (not shown) when loaded into the disk drive device 1 and is driven to rotate at a constant linear velocity (CLV) by a spindle motor 2 during a recording / reproducing operation.
During reproduction, mark information recorded on a track on the optical disk D is reproduced by an optical pickup (optical head unit) OP.
When data is recorded on the optical disc D, user data is recorded as a phase change mark or a dye change mark on a track on the optical disc D by the optical pickup OP.

In the inner peripheral area of the optical disc D, for example, physical information of the disc is recorded as embossed pits or wobbling grooves as reproduction-only management information, and the reading of these information is also performed by the optical pickup OP.
Further, for the optical disk D, ADIP (Address in Pregroove) information embedded as wobbling of the groove track on the optical disk D is also read by the optical pickup OP.

In the optical pickup OP, a laser diode serving as a laser light source, a photodetector for detecting reflected light, an objective lens serving as an output end of the laser light, laser light is irradiated onto the disk recording surface via the objective lens, and An optical system or the like for guiding the reflected light to the photodetector is formed.
In the optical pickup OP, the objective lens is held movably in the tracking direction and the focus direction by a biaxial mechanism.
The entire optical pickup OP can be moved in the disk radial direction by the thread mechanism 3.
The laser diode in the optical pickup OP is driven to emit laser light by a drive signal (drive current) from the laser driver 13.

Reflected light information from the optical disc D is detected by a photodetector, and is supplied to the matrix circuit 4 as an electric signal corresponding to the amount of received light.
The matrix circuit 4 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 photodetectors, and generates necessary signals by matrix calculation processing.
For example, a reproduction signal (RF signal) obtained by reproducing a signal recorded on the optical disc D, a focus error signal for servo control, a tracking error signal, and the like are generated.
Further, a push-pull signal is generated as a signal related to groove wobbling, that is, a signal for detecting wobbling.
The RF signal output from the matrix circuit 4 is supplied to the data detection processing unit 5 and the level measurement unit 19, the focus error signal and the tracking error signal are supplied to the optical block servo circuit 11, and the push-pull signal is supplied to the wobble signal processing circuit 15, respectively. Is done.

  Here, the RF signal supplied from the matrix circuit 4 to the data detection processing unit 5 and the level measurement unit 19 is a signal component (hereinafter referred to as an AC component) that is AC-coupled by a capacitor.

The data detection processing unit 5 performs binarization processing on the RF signal.
For example, the data detection processing unit 5 performs a reproduction clock generation process using a PLL based on an RF signal, PR (Partial Response) equalization process, Viterbi decoding (maximum likelihood decoding), and the like, and a partial response maximum likelihood decoding process (PRML detection method: A binary data string is obtained by the Partial Response Maximum Likelihood detection method.
Then, the data detection processing unit 5 supplies a binary data string corresponding to the binarized code recorded on the optical disc D to the subsequent encoding / decoding unit 7.

  The encode / decode unit 7 performs demodulation of reproduction data during reproduction and modulation processing of recording data during recording. That is, data demodulation, deinterleaving, ECC decoding, address decoding, etc. are performed during reproduction, and ECC encoding, interleaving, data modulation, etc. are performed during recording.

At the time of reproduction, the binary data string decoded by the data detection processing unit 5 is supplied to the encoding / decoding unit 7. The encoding / decoding unit 7 performs demodulation processing on the binary data string to obtain reproduction data from the optical disc D.
For example, the reproduction data from the optical disc D is obtained by performing demodulation processing on data recorded on the optical disc D subjected to run-length limited code modulation and ECC decoding processing as error correction.
The data decoded to the reproduction data by the encoding / decoding unit 7 is transferred to the host interface 8 and transferred to the host device 100 based on an instruction from the system controller 10. The host device 100 is, for example, a computer device or an AV (Audio-Visual) system device.

When recording / reproducing with respect to the optical disc D, processing of ADIP information is performed.
That is, the push-pull signal output from the matrix circuit 4 as a signal related to groove wobbling is converted into wobble data digitized by the wobble signal processing circuit 6. A clock synchronized with the push-pull signal is generated by the PLL process.
The wobble data is demodulated into a data stream constituting an ADIP address by the ADIP demodulation circuit 16 and supplied to the address decoder 9.
The address decoder 9 decodes the supplied data, obtains an address value, and supplies it to the system controller 10.

At the time of recording, recording data is transferred from the host device 100, and the recording data is supplied to the encoding / decoding unit 7 via the host interface 8.
In this case, the encoding / decoding unit 7 performs error correction code addition (ECC encoding), interleaving, sub-code addition, and the like as recording data encoding processing. Further, the run-length limited code modulation is performed on the data subjected to these processes.

The recording data processed by the encoding / decoding unit 7 is subjected to a recording compensation process in the write strategy unit 14 as a recording compensation process. The laser drive pulse is subjected to waveform adjustment and the like, and is supplied to the laser driver 13.
Then, the laser driver 13 supplies the laser drive pulse subjected to the recording compensation process to the laser diode in the optical pickup OP to execute the laser emission driving. As a result, a mark corresponding to the recording data is formed on the optical disc D.

The laser driver 13 includes a so-called APC circuit (Auto Power Control), and the laser output depends on the temperature or the like while monitoring the laser output power by the output of the laser power monitoring detector provided in the optical pickup OP. Control to be constant.
The target value of the laser output at the time of recording and reproduction is given from the system controller 10, and control is performed so that the laser output level becomes the target value at the time of recording and reproduction.
The optimum laser power at the time of recording is set by an OPC process (initial OPC process / WOPC process) described later.

The optical block servo circuit 11 generates various servo drive signals for focus, tracking, and thread from the focus error signal and tracking error signal from the matrix circuit 4 and executes the servo operation.
That is, a focus drive signal and a tracking drive signal are generated according to the focus error signal and tracking error signal, and the biaxial driver 18 drives the focus coil and tracking coil of the biaxial mechanism in the optical pickup OP. Thus, a tracking servo loop and a focus servo loop are formed by the optical pickup OP, the matrix circuit 4, the optical block servo circuit 11, the biaxial driver 18, and the biaxial mechanism.
The optical block servo circuit 11 turns off the tracking servo loop in response to a track jump command from the system controller 10 and outputs a jump drive signal to execute a track jump operation.
The optical block servo circuit 11 generates a thread drive signal based on a thread error signal obtained as a low frequency component of the tracking error signal, access execution control from the system controller 10, and the like. To drive. Although not shown, the sled mechanism 3 has a mechanism including a main shaft that holds the optical pickup OP, a sled motor, a transmission gear, and the like. The sled mechanism 3 is driven by a sled drive signal according to a sled drive signal. The slide movement is performed.

The spindle servo circuit 12 performs control to rotate the spindle motor 2 at CLV.
The spindle servo circuit 12 obtains the clock generated by the PLL processing for the wobble signal as the current rotational speed information of the spindle motor 2, and compares it with predetermined CLV reference speed information to generate a spindle error signal. .
Further, at the time of data reproduction, the reproduction clock generated by the PLL in the data signal processing circuit 5 becomes the current rotational speed information of the spindle motor 2, so that the spindle is compared with predetermined CLV reference speed information. An error signal can also be generated.
The spindle servo circuit 12 outputs a spindle drive signal generated according to the spindle error signal, and causes the spindle driver 17 to execute CLV rotation of the spindle motor 2.
Further, the spindle servo circuit 12 generates a spindle drive signal in response to a spindle kick / brake control signal from the system controller 10, and also executes operations such as starting, stopping, acceleration, and deceleration of the spindle motor 2.

Various operations of the servo system and the recording / reproducing system as described above are controlled by a system controller 10 formed by a microcomputer.
The system controller 10 executes various processes in accordance with commands from the host device 100 given via the host interface 8.
For example, when a recording command (recording command) is issued from the host device 100, the system controller 10 first moves the optical pickup OP to an address to be written. Then, the encoding / decoding unit 7 causes the encoding process to be executed on the user data (for example, video data, audio data, etc.) transferred from the host device 100 as described above. Recording is executed by the laser driver 13 driving to emit laser light according to the data encoded as described above.

For example, when a read command for transferring certain data recorded on the optical disc D is supplied from the host device 100, the system controller 10 first performs seek operation control with the instructed address as a target. That is, a command is issued to the optical block servo circuit 11, and the access operation of the optical pickup OP targeting the address designated by the seek command is executed.
Thereafter, operation control necessary for transferring the data in the designated data section to the host device 100 is performed. That is, the reproduction processing in the data detection processing unit 5 and the encoding / decoding unit 7 is executed, and the requested data is transferred.

Here, as described above, the RF signal (AC component) obtained by the matrix circuit 4 is also supplied to the level measuring unit 19.
The level measurement unit 19 measures (detects) the envelope top level and bottom level for the AC component of the RF signal and supplies the result to the system controller 10 during an OPC operation described later.

The memory unit 20 is configured by, for example, a nonvolatile memory that stores parameters, coefficients, and the like used by the system controller 10 for various processes.
The target value (β-TG) of the evaluation value (β value) necessary for the OPC process and the coefficient (a, b) for the correction process of the evaluation value are stored in the memory unit 20. In addition, a value such as a target value (Vopc-TG) of the evaluation value Vopc calculated by processing as an embodiment described later is also stored in the memory unit 20.

The example of FIG. 2 has been described as a disk drive device connected to the host device 100, but the optical drive device of the present invention may have a form that is not connected to other devices. In that case, an operation unit and a display unit are provided, and the configuration of an interface part for data input / output is different from that in FIG. That is, it is only necessary that recording and reproduction are performed in accordance with a user operation and a terminal unit for inputting / outputting various data is formed. Of course, various other examples of the configuration of the optical drive device are conceivable.

<3. WOPC as an embodiment>
[3-1. WOPC as a first example]

At the time of recording on a multilayer optical recording medium having a plurality of recording layers like the optical disc D of the present embodiment, as described above, the other recording layers are adjusted with the recording laser power adjusted when the other recording layers are unrecorded. When recording a position in which the other recording layer is in the recording state, or conversely, when recording a position in which the other recording layer is in the unrecorded state with the recording laser power adjusted when the other recording layer is in the recording state. Therefore, it is difficult to perform recording with stable laser quality.

In view of this point, in the present embodiment, the detection operation of the reflected light is performed in advance before the recording operation is performed on the pre-recording area of the optical recording medium, and the recording laser power is based on the reflected light information detected thereby. The method of performing the adjustment control is adopted.
Specifically, regarding the laser power adjustment processing performed for each WOPC section at the time of WOPC, the calculated β value is corrected based on reflected light information detected in advance before recording, and the corrected β value is set in advance. The recording laser power is adjusted so as to match the target value (target value).

FIG. 3 is a diagram for explaining the outline of WOPC as such an embodiment.
In FIG. 3, “write section” in the drawing represents a recording section for a series of data instructed to be recorded by a recording command, for example. As described above, when WOPC is performed, the WOPC section is set by a predetermined section length, for example, every 1 mm in radius. Therefore, the write section is divided into a plurality of WOPC sections as shown in the figure. Can be represented as
In each WOPC section, a section in which a recorded signal is reproduced in measuring a β value as an evaluation value is determined in advance, and this is referred to as an evaluation value measurement section.
In this case, the evaluation value measurement section is set at the end portion of the WOPC section as shown in the figure, thereby shortening the seek time from the recording completion position of the WOPC section to the β value measurement start position, As a result, the time required for the WOPC process is reduced.

In the WOPC process of the present embodiment, first, as shown by <1> in the figure, the amplitude level (PreRec Lv) of the RF signal in the evaluation value measurement section before recording is measured. That is, the RF amplitude level is measured in the unrecorded evaluation value measurement section before recording on the WOPC section.
Thus, the RF amplitude level measured in the pre-recording area reflects the recorded / unrecorded state in the other recording layer.

Then, after measuring the RF amplitude level (PreRec Lv) in advance as described above, the WOPC section is recorded (<2>), and then the top level of the RF signal (AC component) in the evaluation value measuring section. Then, the bottom level is measured (<3>) and the β value is calculated (<4>).
Here, the β value is calculated by the following [Expression 1] when the top level and the bottom level of the envelope of the RF signal (AC component) are Top Lv and Bottom Lv, respectively.

β = (Top Lv + Bottom Lv) / (Top Lv−Bottom Lv) [Formula 1]

For confirmation, Top Lv> 0 and Bottom Lv <0.

In the present embodiment, after the β value is calculated in this way, an evaluation value Vopc in which the β value is corrected according to the value of the RF amplitude level PreRec Lv measured in advance is calculated (<5>). ).
Then, the recording laser power is adjusted so that the evaluation value Vopc becomes a preset target value (Vopc-TG) (<6>).

  Here, regarding the WOPC processing as the present embodiment, the RF amplitude level PreRec Lv measured in advance reflects the recorded / unrecorded state of other recording layers as described above. It becomes. Specifically, the level becomes large or small when the other recording layer has been recorded and when the other recording layer has not been recorded.

On the other hand, when the conventional WOPC described with reference to FIG. 10 is performed, the reason why recording cannot be performed with a stable quality on the multilayer optical recording medium is that the other layers are not recorded / unrecorded. In some cases, the calculated β value changes.
Specifically, when recording is performed in the other layer, the leakage of the recording signal in the other layer acts in the direction of increasing the amplitude of the AC component of the RF signal, so that the β value has the denominator of [Expression 1]. The value “Top Lv−Bottom Lv” tends to increase, and as a result, the value tends to decrease.
On the other hand, when the other layer is not recorded, the value of the denominator in [Equation 1] is small, and therefore the β value is large.

  As described above, since the β value changes according to recording / non-recording of the other layer, as described with reference to FIG. 11, the other layer is not recorded with the power adjusted when the other layer is recorded. When recording the position of, or when recording the position where the other layer is recorded with the power adjusted when the other layer is not recorded, the recording is performed with a power greatly deviating from the optimum power End up. That is, as a result, the recording quality is not stable due to the mixed state of good / bad recording quality due to whether the other layer is recorded / unrecorded.

In order to stabilize the recording quality, the β value may be corrected so that the β values calculated when the other layer is recorded and when the other layer is not recorded have the same value.
For example, ideally, if the same β value can be calculated when the other layer is recorded and when the other layer is not recorded, recording / unrecorded of the other layer at the time of evaluation value measurement and actual recording It is possible to completely prevent the difference in recording quality as described above when the recording / non-recording of the other layer does not match.
As can be understood from this, in order to stabilize the recording quality, the β value is corrected so that the values calculated at least when the other layer is recorded and when there is no recording are close to each other. Just do it.

  In the present embodiment, from such a viewpoint, as shown by <5> in FIG. 3, a method of correcting the calculated β value according to the value of the RF amplitude level PreRec Lv acquired in advance before recording is performed. Is supposed to be adopted.

Here, as described above, a specific method for correcting the β values calculated when the other layers are recorded / unrecorded to be the same value (at least approach) using the RF amplitude level PreRec Lv as described above. In other words, various specific methods for calculating the above-described evaluation value Vopc can be considered.
In the present embodiment, as a specific calculation method of such an evaluation value Vopc, the first calculation method and the second calculation method are given as examples.

  On the other hand, examples of the RF amplitude level PreRec Lv include an example using the amplitude level of the AC component of the RF signal and an example using the DC component (component before AC coupling).

Hereinafter, an example in which the first calculation method is employed as the calculation method of the evaluation value Vopc and the amplitude level of the AC component of the RF signal is used as the RF amplitude level PreRec Lv will be described as a “first example”.
It is to be noted that “second example” to be described later adopts the second calculation method as the evaluation value Vopc calculation method and uses the amplitude level of the DC component of the RF signal as the RF amplitude level PreRec Lv.

~ Specific method ~

Hereinafter, the first example of the embodiment will be specifically described.
In the first example, the evaluation value Vopc is calculated by the following [Equation 2].

Vopc = {(Top Lv + Bottom Lv) −a (PreRec Top Lv−PreRec Bottom Lv) + b} / (Top Lv−Bottom Lv) [Equation 2]

However, in [Formula 2], PreRec Top Lv and PreRec Bottom Lv are the top level and bottom level (envelope top level and bottom level) of the AC component of the RF signal measured in advance in the evaluation value measurement area before recording. Further, a and b are coefficients obtained experimentally in advance.

  According to the above [Equation 2], by appropriately setting the values of the coefficients a and b, the β value is corrected so that the same value can be obtained when the other layer is recorded and when the other layer is not recorded. Can do. In other words, the values of the coefficients a and b are set in advance so that the value of Vopc calculated by the above [Equation 2] is the same value when the other layer is recorded and when the other layer is not recorded. It is determined from the results of experiments.

FIG. 4 is a diagram for explaining the relationship between the evaluation value Vopc calculated by [Equation 2] and the recording laser power.
In FIG. 4, the relationship between the recording laser power and the β value is also shown for comparison. As shown in the figure, the gray solid line indicates the β value when there is no recording in the other layer, and the gray broken line indicates the β value when there is recording in the other layer.
Further, in FIG. 4, the relationship between the recording laser power and iMLSE (evaluation value of error rate correlation) when there is no recording in the other layer (solid line of gray and x-marked plot), and the recording laser when there is no recording in the other layer The relationship between power and iMLSE (gray and broken line in bar plot) is also shown.

  Referring to FIG. 4, the difference between the value of evaluation value Vopc in the case of no other layer recording and the value of evaluation value Vopc in the case of other layer recording is the difference between the β value in the case of no other layer recording and the value of other layer recording. Therefore, the evaluation value in this case is corrected to tend to be the same in the case of no other layer recording and in the case of other layer recording. You can see that. In other words, correction is performed so as to reduce the difference between the evaluation values calculated in both cases.

Here, as the target value (Vopc-TG) of the evaluation value Vopc in this case, a value different from the target value (β-TG) of the β value is set.
The target value Vopc-TG of the evaluation value Vopc is set in advance based on [Expression 2] at the time of initial OPC.

The initial OPC is a test writing performed while changing the recording laser power in a test area provided outside the user data area where the WOPC is performed, such as the innermost peripheral area of the optical disc D, and the test writing was performed. This refers to an operation for obtaining the optimum recording laser power based on the result of signal evaluation. Specifically, a β value is calculated for a signal recorded under each power setting, and the calculated β value is closest to a preset target value of β value (referred to as target value β-TG). The recording laser power is determined as the optimum recording laser power.
In the first example, the target value Vopc-TG is obtained by preliminarily calculating the top level PreRec Top Lv and the bottom level PreRec Bottom Lv of the RF signal AC component before recording in the test area where the test writing is performed in such initial OPC. The top level of the RF signal AC component that was acquired and used to calculate the β value in the section that was trial-written under the settings of the top level PreRec Top Lv and bottom level PreRec Bottom Lv and the above-described optimum recording laser power It calculates | requires by calculating previous [Formula 2] using Top Lv and bottom level Bottom Lv. That is, the evaluation value Vopc calculated by [Equation 2] using PreRec Top Lv, PreRec Bottom Lv, Top Lv, and Bottom Lv at the time of initial OPC is set in advance as the target value Vopc-TG used at the time of WOPC. It is something to keep.

  In this way, the β value (≈target value β-TG) obtained under the setting of the optimum laser power obtained from the result of actual test writing at the time of initial OPC is expressed by [Expression 2]. It correct | amends and the value is set as the target value Vopc-TG of the evaluation value Vopc at the time of WOPC.

Here, the target value Vopc-TG calculated as described above may be different depending on whether the test area where the initial OPC is performed has no other layer recording or other layer recording. It will be. This is apparent when the value of “PreRec Top Lv−PreRec Bottom Lv” in [Formula 2] is different between the case without other layer recording and the case with other layer recording.
From this point, the test area for performing the initial OPC is set to either an area in which the other layer is guaranteed not to be recorded or an area in which the other layer is guaranteed to be recorded. There is a need. At this time, providing an area in which another layer is guaranteed to be recorded means that a mark is recorded in advance on the corresponding portion of the optical disc D, so it is not realistic. It becomes. From this point, it is assumed that in the present example, the test area is set as an area in which the other layer is guaranteed not to be recorded.

By the way, in the case where the test area where the initial OPC is performed is an area where it is guaranteed that there is no other layer recording, the same target value β-TG as in the conventional case (β-TG = in the example shown in FIG. 11). 0.05), the recording laser power obtained by the initial OPC is an optimum laser power when the other layer is not recording, and the recording operation by the laser power is performed. When this is executed, the signal quality is greatly deteriorated in the section where the other layer is recorded.
Therefore, in this example, the target value β-TG is different from the conventional value in order to prevent the laser power obtained by the initial OPC from becoming an optimum value only when there is no other layer recording. The value is supposed to be set. Specifically, the target value β-TG is set so that a laser power that does not cause a difference in signal quality between the case of no other layer recording and the case of other layer recording is obtained by the initial OPC. .
As an example, as a specific numerical value of such a target value β-TG, for example, about 0.1 is set in the example of FIG. In FIG. 11, when the target value β-TG = 0.1 is set in this way, the recording laser power obtained by the initial OPC is the optimum power in the case of no other layer recording (the point where iMLSE is minimized = 14 mW). About halfway between the optimum power (about 16 mW) when there is no recording on the other layer. That is, by this, at the initial OPC, the laser power is set so as not to cause a difference in signal quality between the case of no other layer recording and the case of other layer recording.

Return to the explanation at the time of WOPC.
As described above with reference to FIG. 3, the WOPC in this case is such that the value of the evaluation value Vopc calculated by [Equation 2] becomes the target value Vopc-TG set in advance at the initial OPC as described above. This is done by adjusting the recording laser power.
At this time, as described above, the evaluation value Vopc is a value calculated so as to be the same value when the other layer is not recorded / recorded. As is clear from the above description, the target value Vopc-TG is the evaluation value Vopc at the optimum point of the recording laser power obtained by the initial OPC (the optimum point determined based on the actually measured β value).
From these points, the evaluation value measurement section is not recorded in the other layer by adjusting the recording laser power so that the evaluation value Vopc becomes the target value Vopc-TG as described above. In this case, adjustment is performed so that the recording laser power becomes almost the same between the case where recording is performed and the case where recording is performed on another layer. That is, the laser power in this case is adjusted to a value near the middle between the optimum point when the other layer is not recorded and the optimum point when the other layer is recorded (see FIG. 4).
As described above with reference to FIG. 11, the optimum point of the recording laser power when the other layer is not recorded is about 14 mW, and the optimum point when the other layer is recorded is about 16 mW. Yes, this caused a large quality difference between when the other layer was not recorded and when the other layer was recorded in the actual recording section. According to the WOPC of this embodiment, the recording laser power is Since, as described above, the adjustment is made in the middle of the optimum point when the other layer is not recorded and the optimum point when the other layer is recorded, the optimum point when the other layer is not recorded / is present in the actual recording section Deviation (that is, quality difference) can be suppressed accordingly. Therefore, the recording quality can be stabilized by suppressing the difference in quality due to the absence / presence of recording in the other layer as compared with the prior art.

~ Processing procedure ~

Subsequently, a specific processing procedure to be performed in order to realize the technique as the first example described above will be described with reference to the flowcharts of FIGS. 5 and 6.
FIG. 5 shows a specific processing procedure to be performed corresponding to the above-described initial OPC, and FIG. 6 shows a specific processing procedure to be performed corresponding to the WOPC.
5 and 6 show processing for realizing the technique as the first example as processing executed by the system controller 10 shown in FIG. 2 in accordance with a program stored in the memory unit 20.

First, the processing of FIG. 5 corresponding to the initial OPC will be described.
In FIG. 5, in step S101, the process waits until an initial OPC start trigger is generated. That is, the determination process as to whether or not the initial OPC start trigger has occurred is repeatedly executed until a positive result is obtained by the determination process.

If a positive result is obtained in step S101 that an initial OPC start trigger has occurred, in step S102, the top level (PreRec Top Lv) and bottom level (PreRec Bottom) of the RF signal before recording in the initial OPC section are obtained. The process for measuring Lv) is executed.
In other words, the seek operation control for the optical block servo circuit 11 shown in FIG. 2 is performed, and laser light irradiation and reflected light detection are performed by the optical pickup OP for the section on the optical disc D where initial OPC is to be performed. Thus, the level measurement unit 19 measures the top level PreRec Top Lv and the bottom level PreRec Bottom Lv of the RF signal AC component before recording in the initial OPC section.
The system controller 10 temporarily holds the values of PreRec Top Lv and PreRec Bottom Lv at the time of the initial OPC thus measured in the memory unit 20 illustrated in FIG.

After performing the pre-recording measurement process in step S102 as described above, an initial OPC process (S103 to S105) surrounded by a broken line in the figure is executed.
That is, as the initial OPC process, first, in step S103, a process for executing test writing with each power is performed. Specifically, seek operation control or encoding / decoding for the optical block servo circuit 11 is performed so that a test signal recording operation in which the recording laser power is sequentially changed is executed for each test interval set in the initial OPC interval. A recording instruction to the unit 7 and a recording laser power instruction to the laser driver 13 are performed.

In the subsequent step S104, a process for measuring the β value is executed for each trial writing section with each power.
That is, the optical signal is measured so that the measurement results of the top level Top Lv and the bottom level Bottom Lv of the RF signal AC component by the level measurement unit 19 are obtained for each test section in which the test signals are recorded with different powers as described above. In addition to performing seek operation control for the block servo circuit 11 and the like, the β value is calculated according to the above [Equation 1] for each test section based on the measured Top Lv and Bottom Lv values.

Further, in the next step S105, a process of holding the power when the β value closest to the target value β-TG is obtained as the initial OPC optimum power is executed.
That is, among the β values acquired for each test section (that is, for each recording laser power) as described above, the β value closest to the preset target value β-TG (for example, stored in the memory unit 20). The recording laser power when the β value is obtained is held as the optimum recording laser power at the initial OPC.

In the subsequent step S106, based on Top Lv, Bottom Lv, PreRec Top Lv, and PreRec Bottom Lv obtained in the optimum power setting section, processing for calculating the evaluation value Vopc by [Expression 2] is executed.
That is, the values of the top level Top Lv and bottom level Bottom Lv of the RF signal AC component in the setting section of the optimum laser power obtained in the process of measuring the β value in step S104, and before recording in the previous step S102. Using the values of the top level PreRec Top Lv and the bottom level PreRec Bottom Lv of the acquired RF signal AC component and the values of the coefficients a and b stored in the memory unit 20 in advance, the calculation according to [Expression 2] is performed. Thus, the evaluation value Vopc is obtained.

Then, in the next step S107, the evaluation value Vopc at the time of the initial OPC calculated in this way is held as the target value Vopc-TG. The target value Vopc-TG is held in the memory unit 20, for example.
With the execution of the processing in step S107, the processing operation corresponding to the initial OPC shown in FIG.

Next, processing corresponding to the time of WOPC will be described with reference to FIG.
In FIG. 6, first, in step S201, a recording command from the host device 100 side shown in FIG.
If a positive result is obtained as a result of the recording command, the section count value n is set to 1 in step S202, and the N value is set in the next step S203.
Here, the section count value n is a value held by the system controller 10 in order to grasp the WOPC section currently being recorded.
As the N value, the total number of WOPC sections to be included in the recording section when the data designated by the recording command is recorded is set. The N value can be calculated from the section length information for recording the data instructed by the recording command and the WOPC section length information set in advance.

In the subsequent step S204, processing for measuring the top level (PreRec Top Lv) and bottom level (PreRec Bottom Lv) of the RF signal before recording in the evaluation value measurement section in the nth WOPC section is performed.
That is, level measurement is performed by performing seek operation control or the like on the optical block servo circuit 11 and performing laser light irradiation and reflected light detection by the optical pickup OP for the section corresponding to the nth WOPC section on the optical disc D. The unit 19 measures the top level PreRec Top Lv and the bottom level PreRec Bottom Lv of the RF signal AC component before recording in the nth WOPC section.
Also in this case, the measured values of PreRec Top Lv and PreRec Bottom Lv in the nth WOPC section are temporarily stored in the memory unit 20, for example.

In this way, after acquiring the values of PreRec Top Lv and PreRec Bottom Lv in the nth WOPC section, in the next step S205, processing for recording the nth WOPC section is executed. That is, data to be recorded in the nth WOPC section of the series of data instructed by the recording command is recorded in the nth WOPC section.
Note that the optimum recording laser power obtained by the initial OPC is set as the recording laser power when recording the WOPC section of n = 1 immediately after the initial OPC.

  Further, in the subsequent step S206, processing for measuring the top level (Top Lv) and bottom level (Bottom Lv) of the RF signal (AC component) after recording of the evaluation value measurement section in the nth WOPC section is executed. .

  Then, in the next step S207, the evaluation value Vopc is calculated by [Expression 2]. That is, the Top Lv and Bottom Lv values obtained in step S206, the PreRec Top Lv and PreRec Bottom Lv values obtained in the previous step S204, and the coefficient a stored in the memory unit 20 in advance. , B is used to calculate [Equation 2] to obtain an evaluation value Vopc.

In the subsequent step S208, the recording laser power is adjusted based on the evaluation value Vopc and the target value Vopc-TG. That is, the recording laser power is adjusted so that the evaluation value Vopc obtained in step S207 matches the target value Vopc-TG set during the initial OPC.
Specifically, if the evaluation value Vopc is smaller than the target value Vopc-TG, adjustment is performed to increase the recording laser power according to the difference.
If the evaluation value Vopc is larger than the target value Vopc-TG, adjustment is performed so as to reduce the recording laser power according to the difference.

  In the next step S209, it is determined whether or not n = N, that is, whether or not all data designated by the recording command has been recorded. If a negative result is obtained in step S209 that n = N is not satisfied, the process proceeds to step S210 to increment the section count value n by 1 (n = n + 1), and then returns to the previous step S204.

On the other hand, if a positive result is obtained in step S209 that n = N, the corresponding processing at the time of WOPC shown in this figure ends.

[3-2. WOPC as a second example]

Subsequently, a second example of the embodiment will be described.
As mentioned earlier, the second example uses the DC component instead of the AC component of the RF signal for correcting the β value (calculation of the evaluation value Vopc), and the calculation method of the first example is as follows. The evaluation value Vopc is calculated by a different second calculation method.

-Configuration of optical drive device-

FIG. 7 shows the internal configuration of the disk drive device 30 in the second example.
In FIG. 7, parts that are the same as those already described in FIG. 2 are given the same reference numerals, and descriptions thereof are omitted.
In FIG. 7, the changes from the first example are that a level measurement unit 31 is provided instead of the level measurement unit 19, and that the matrix circuit 4 is not limited to the AC component of the RF signal with respect to the level measurement unit 31. The DC component is also configured to be output.
The level measuring unit 31 measures the top level and the bottom level of the envelope of the AC component of the RF signal input from the matrix circuit 4 and measures the top level of the DC component of the RF signal.

~ Specific method ~

In the second example, the top level (hereinafter referred to as PreRec DC Top Lv) of the DC component of the RF signal in the pre-recording area is measured, and the evaluation value Vopc is calculated using the value of the PreRec DC Top Lv. Calculate according to [Equation 3].

Vopc = β × {c × ((PreRec DC Top Lv Std / PreRec DC Top Lv) −1) +1}
... [Formula 3]

However, in [Expression 3], PreRec DC Top Lv Std is a reference level for the top level PreRec DC Top Lv of the DC component of the RF signal in the pre-recording region, and is measured and held in advance at the time of the initial OPC.
The value c is a value that should be experimentally obtained in advance. Specifically, the value c is calculated when the other layer is recorded and when the other layer is not recorded. The evaluation value Vopc is selected so that the same value is obtained (so that the difference between the values is reduced).
The value c is stored in advance in the memory unit 20 or the like.

Here, in the second example as well, the area where the initial OPC is performed is set to be an area where it is guaranteed that no recording is performed on the other layer, for the same purpose as in the first example. It is said. Thus, the reference level PreRec DC Top Lv Std that is measured in advance during the initial OPC in the second example as described above is a value that is measured when the other layer is not recorded.
Also in the second example, the target value β-TG of the β value used at the time of initial OPC is not set to the same value (for example, 0.05) as in the prior art, and the case of no other layer recording and the case of other layer recording A value (for example, 0.1) is set such that the laser power that can prevent the difference in signal quality from the existing case (can reduce the signal quality difference) is obtained by the initial OPC.

  Based on these assumptions, according to the above [Equation 3], the β value calculated at the time of WOPC is the top level PreRec DC Top Lv of the RF signal DC component measured in advance before recording the evaluation value measurement section ( It will be understood that the correction is made in accordance with the ratio between the value of “level before recording at WOPC” and the value of the reference level PreRec DC Top Lv Std. Specifically, the correction is made according to the value of the reference level / the level before recording at WOPC.

Here, the top level value of the DC component of the RF signal tends to be relatively small when the other layer is recorded and relatively large when the other layer is not recorded.
Considering this point and the fact that the reference level PreRec DC Top Lv Std is measured without recording on the other layer as described above, depending on the above [Equation 3], there are others in the evaluation value measurement section at the time of WOPC. When the layer is recorded, the value of “PreRec DC Top Lv Std / PreRec DC Top Lv” tends to be large, and the β value is corrected to be relatively large.
On the other hand, when the other layer is not recorded in the evaluation value measurement section, the value of {c × ((PreRec DC Top Lv Std / PreRec DC Top Lv) −1) +1} in [Expression 3] is “1”. ("PreRec DC Top Lv Std / PreRec DC Top Lv" = 1), and as a result, the β value is maintained as it is.

Here, also in the second example, the target value Vopc-TG of the evaluation value Vopc is obtained in advance at the time of the initial OPC. Specifically, the evaluation value Vopc obtained by correcting the β value (≈β-TG) measured under the setting of the optimum laser power by [Equation 3] is used as the target value Vopc-TG used at the time of WOPC. I ask for it.
More specifically, the top level PreRec DC Top Lv of the RF signal DC component measured in advance in the pre-recording area in the test area where the initial OPC is performed, the reference level PreRec DC Top Lv Std, and the optimum laser power are set. The evaluation value Vopc is calculated by [Equation 3] using the β value calculated below (approx. Β-TG), and the evaluation value Vopc is set as the target value Vopc-TG.

In the initial OPC, the RF signal DC component top level PreRec DC Top Lv measured in advance in the pre-recording area has the same meaning as the reference level PreRec DC Top Lv Std. Further, the β value calculated under the setting of the optimum laser power as described above can be regarded as synonymous with the target value β-TG.
From these points, the target value Vopc-TG can be set to Vopc-TG = β-TG without being calculated by [Equation 3]. That is, the target value β-TG set in advance as the target value at the time of initial OPC can be used as the target value Vopc-TG at the time of WOPC.

  Here, as described above, in the second example, when the other layer is not recorded in the evaluation value measurement section, the value of the evaluation value Vopc obtained by [Equation 3] becomes the measured β value itself, and When the other layer is recorded in the evaluation value measurement section, the evaluation value Vopc obtained by [Equation 3] is corrected in the direction of increasing the measured β value.

At this time, since the target value Vopc−TG≈target value β−TG as described above, if the other layer is not recorded in the evaluation value measurement section, the evaluation value Vopc (in this case) measured there Is the β value itself), the laser power is adjusted so as to match the target value Vopc-TG, the laser power is the optimum point when there is no other layer recording and the optimum point when there is other layer recording Will be adjusted around the middle.
This is based on the premise that the initial OPC is performed in an area in which no other layer recording is guaranteed as described above, and the target value β-TG is set to the value obtained when there is no other layer recording. This is apparent in view of the fact that the laser power capable of reducing the signal quality difference between the case of recording and the case of recording is set to be obtained by the initial OPC.
That is, referring to the drawing, as described above, when the evaluation value measurement section is not recorded in another layer (that is, the evaluation value Vopc = β value), the target value Vopc−TG≈the target value β−TG is set as follows: Since this corresponds to a state in which β-TG = 0.1 is set for the characteristic of “no other layer recording” in FIG. 11 (straight line), the result is adjusted based on β-TG = 0.1. The laser power is adjusted in the vicinity of an intermediate point between the optimum point when there is no other layer recording and the optimum point when there is other layer recording.

On the other hand, when there is another layer recording in the evaluation value measurement section, the evaluation value Vopc corrected in the direction of increasing the β value measured there is obtained.
Here, the recording laser power adjusted in a state where the other layer is recorded becomes excessive when recording is performed at a position where the other layer is not recorded (see FIG. 11).
Further, the adjustment of the recording laser power is performed such that the power is decreased when the β value is large, and conversely, the power is increased when the β value is small.
Therefore, when the other layer is recorded in the evaluation value measurement section as described above, the correction is performed in the direction in which the β value is increased. The recording laser power that should have been set can be adjusted to be lower than an excessive value.
In other words, it is possible to set the laser power that can reduce the difference in signal quality between the case where the evaluation value measurement section has other layer recording and the other layer has no recording and the other layer has recording. Can do.

As can be understood from the above description, the second example can also stabilize the recording quality of the multilayer optical recording medium.

~ Processing procedure ~

The flowcharts of FIGS. 8 and 9 show the procedure of specific processing to be performed in the second example.
FIG. 8 shows a specific processing procedure to be performed corresponding to the initial OPC, and FIG. 9 shows a specific processing procedure to be performed corresponding to the WOPC.
8 and 9, a specific processing procedure to be performed in the second example is a processing procedure executed by the system controller 10 shown in FIG. 7 based on a program stored in the memory unit 20. As shown.
In FIGS. 8 and 9, processes having the same contents as those already described with reference to FIGS. 5 and 6 are denoted by the same step numbers and description thereof is omitted.

  In FIG. 8, at the time of the initial OPC in this case, in response to obtaining an affirmative result that the initial OPC start trigger has occurred in step S <b> 101, step S <b> 301 in the figure is substituted for the process of step S <b> 102 in FIG. 5. Execute the process. That is, in this step S301, a process of measuring the DC component top level (PreRec DC Top Lv) of the RF signal before recording in the initial OPC section and holding it as the reference level PreRec DC Top Lv std is executed.

In this case, the process of step S302 is executed instead of the process of step S106 in FIG. 5 (calculation process of a value to be the target value Vopc-TG).
In this step S302, the evaluation value Vopc is calculated by [Equation 3] based on the β value obtained in the optimum power setting section and the reference level PreRec DC Top Lv std.

  As described above, the value of the top level PreRec DC Top Lv of the RF signal DC component in the pre-recording region at the time of initial OPC is the value of the reference level PreRec DC Top Lv std of the RF signal DC component acquired in step S301. Further, the β value obtained in the optimum power setting section can be regarded as the same value as the target value β-TG used in the initial OPC. Therefore, [Equation 3] to be calculated at the time of the initial OPC can be read as Vopc (Vopc−TG) ≈β−TG, and therefore the calculation process in step S302 can be omitted.

  After executing the process of step S302, in step S107, the calculated evaluation value Vopc is held as the target value Vopc-TG.

Subsequently, as the corresponding process at the time of WOPC shown in FIG. 9, the process of steps S201 to S203 is first executed in this case as in the case of the first example.
In this case, instead of the process of step S204 shown in FIG. 6, a process for measuring the top level (PreRec DC Top Lv) of the RF signal DC component in the evaluation value measurement section in the nth WOPC section is executed. To do. That is, the top level value of the DC component of the RF signal measured by the level measuring unit 31 when the laser light irradiation and reflected light detection by the optical pickup OP is executed for the evaluation value measurement section of the nth WOPC section is acquired. To do.

  In this case, instead of step S207 shown in FIG. 6, a process of calculating the evaluation value Vopc by [Equation 3] is executed as step S402 in the figure. That is, first, after calculating the β value based on the values of the top level Top Lv and the bottom level Bottom Lv of the RF signal AC component obtained in step S206, the β value and the RF value obtained in step S401 are calculated. The value of the top level PreRec DC Top Lv of the signal DC component, the value of the reference level PreRec DC Top Lv std held in step S107 in FIG. 8, and the value of c stored in the memory unit 20 are used. Thus, the evaluation value Vopc is calculated by [Equation 3].

After the evaluation value Vopc based on [Equation 3] is calculated in step S402, the recording laser is calculated based on the evaluation value Vopc and the target value Vopc-TG (the value calculated in step S302 in FIG. 8) in step S208. The power is adjusted.
After adjusting the recording laser power in this way, the process proceeds to step S209, whereby the process of steps S401 → S205 → S206 → S402 → S208 is repeated until n = N, and the WOPC section unit is obtained. Then, the β value correction and the adjustment of the recording laser power based on the corrected β value as the second example are repeated.

<3. Modification>

As mentioned above, although embodiment of this invention has been described, this invention should not be limited to the specific example demonstrated so far.
For example, in the description so far, as a specific method for correcting the β value, when the AC component of the RF signal in the pre-recording area is used, correction according to [Equation 2] is performed, and the DC component of the RF signal in the pre-recording area is calculated. In the case of using, the case of performing the correction by [Equation 3] has been exemplified. For example, when the AC component of the RF signal in the former pre-recording area is used, the β value is corrected in the form of [Equation 3]. You can also.
In that case, at the time of the initial OPC, the top level (PreRec Top Lv) and the bottom level (PreRec Bottom Lv) of the RF signal AC component are measured in advance in the initial OPC section before recording, and in the case of the second example The reference level “PreRec Top Lv−PreRec Bottom Lv” is calculated as a value corresponding to the reference RF amplitude level “PreRec DC Top Lv std”, and the value is held. Here, the value of “PreRec Top Lv−PreRec Bottom Lv” measured in advance in the pre-recording area during initial OPC as described above is expressed as “PreRec Top Lv std−PreRec Bottom Lv std”.
In this case, at the time of WOPC, the evaluation value Vopc is calculated by the following [Equation 4] using the value of the reference level “PreRec Top Lv std−PreRec Bottom Lv std”.

Voc = β × {c × [((PreRec Top Lv−PreRec Bottom Lv) / (PreRec Top Lv Std−PreRec Bottom Lv Std)) − 1] +1} (Formula 4)

Here, since the amplitude level (Dc Top Lv) of the DC component of the RF signal is [small when the other layer is recorded and large when the other layer is not recorded], in the above second example, The β value is corrected according to the value of “reference level / level before recording at WOPC” by [Equation 3]. In contrast, the amplitude level (top level-bottom level) of the AC component of the RF signal is conversely [large when the other layer is recorded and small when the other layer is not recorded]. In view of the above, in [Equation 4], the β value is corrected according to the value of “level before WOPC recording / reference level”.
In this case as well, the initial OPC area is set to an area in which it is guaranteed that recording is not performed on another layer. That is, also in this case, the target value Vopc-TG set at the time of the initial OPC is set to “Vopc-TG = β-TG” as in the case of the second example, and the calculation process can be omitted.

Or, contrary to the above, when the DC component of the RF signal in the pre-recording area is used, the β value can also be corrected in the form of [Equation 2].
Specifically, the correction of the β value at the time of WOPC in that case is performed by the following [Equation 5] when the top level of the RF signal DC component measured in the evaluation value measurement section before recording is PreRec DC Top Lv. .

Vopc = {(Top Lv + Bottom Lv) + a (PreRec DC Top Lv) + b} / (Top Lv−Bottom Lv)
... [Formula 5]

That is, as described above, the AC component and the DC component of the RF signal have an inverse relationship with respect to the amplitude change characteristics with and without other-layer recording. What was corrected by subtracting with Top Lv is changed to be corrected by adding PreRec DC Top Lv in this case.
Note that the target value Vopc-TG in this case may be a value obtained by correcting the β value (≈β-TG) at the optimum power obtained during the initial OPC by the above [Formula 5]. Specifically, at the time of initial OPC, the top level of the RF signal DC component is measured in advance in the initial OPC section before recording, and the value is substituted as “PreRec DC Top Lv” in [Equation 5]. A value obtained by correcting the β value at the optimum power obtained during the initial OPC is set as a target value Vopc-TG.

In addition, in the description so far, it is assumed that a medium whose reflectance is reduced in the mark recording portion (referred to as a normal medium) is used. Conversely, there is a medium whose reflectance is increased in the mark recording portion. .
When such a medium is used, the top level value of the DC component of the RF signal is opposite to that when a normal medium is used. Therefore, the top level value of the DC component of the RF signal is recorded in other layers. In some cases, it becomes large, and in other cases where there is no recording, it becomes small.
[Equation 3] described in the second example above assumes that the top level value of the DC component of the RF signal is large when the other layer is recorded and small when the other layer is not recorded. It was designed as.
However, in the case of a medium in which the reflectance increases at the mark recording portion in this way, the β value characteristic line (solid line) when there is other layer recording in FIG. 11 and the β value when there is no other layer recording. The positional relationship with the characteristic line (a straight line with a broken line) is reversed. That is, in the case of a medium in which the reflectance increases in the recording portion, the optimum power in the case of other layer recording is smaller than the optimum power in the case of no other layer recording.
From these points, even when using a medium whose reflectivity increases at the mark recording portion, the β value is corrected using [Equation 3] itself, which is the same as when using a normal medium. The effect of can be obtained. That is, the recording quality for the multilayer optical recording medium can be stabilized.

In the above description, the case where the present invention is applied to the adjustment of the recording laser power has been exemplified. However, the present invention is also applicable to the case of adjusting other recording parameters other than the recording laser power such as a write strategy. It can be suitably applied.
As exemplified in the embodiment, the recording parameter adjustment control is performed based on the reflected light information previously detected before the recording operation is performed on the pre-recording area, so that recording / non-recording of other recording layers is performed. The recording parameters can be adjusted in consideration of the influence of the difference between the recording layers, and as a result, the recording quality can be stabilized regardless of whether the other layer is recorded or not recorded.

  In the above description, the case where the optical recording medium targeted by the present invention is a four-layer recording medium (the number of recording layers = 4) is exemplified. However, as the present invention, an optical recording medium having a smaller number of layers, Alternatively, the present invention can be suitably applied to the case where recording is performed on a multilayer optical recording medium.

  Further, the present invention can be applied to various optical recording systems including a BD (Blu-ray Disc: registered trademark) system.

  1,30 disk drive device, 5 data detection processing unit, 7 encoding / decoding unit, 10 system controller, 13 laser driver, 14 write strategy unit, 19, 31 level measurement unit, 20 memory unit, OP optical pickup, D optical disk

Claims (14)

A recording unit that records information by irradiating the optical recording medium with laser light;
A reflected light detector for detecting reflected light of the laser light irradiated to the optical recording medium;
Control that performs a reflected light detection operation in advance on the pre-recording area of the optical recording medium before performing a recording operation, and performs recording parameter adjustment control in the recording unit based on the reflected light information detected thereby And an optical drive device. The control unit
After performing the reflected light detection operation for the pre-recording area,
Performing a recording operation on the pre-recording area, calculating an evaluation value of a reproduction signal obtained by reproducing a signal recorded by the recording operation,
The calculated evaluation value is corrected based on the reflected light information about the pre-recording area acquired in advance,
The optical drive apparatus according to claim 1, wherein adjustment control of the recording parameter is performed based on the corrected evaluation value. The optical drive apparatus according to claim 2, wherein the control unit performs parameter adjustment control for recording laser power based on the corrected evaluation value. A WOPC area for performing WOPC (Walking Optimum Power Control) for adjusting the recording laser power based on the result of obtaining the evaluation value of the reproduction signal of the recorded area by sequentially interrupting the recording operation is provided on the optical recording medium. Multiple settings are made in the user data area.
The control unit
For the WOPC area to be recorded, the reflected light detection operation is executed in the evaluation value measurement area set in the WOPC area before the recording, and the WOPC area is recorded after the reflected light detection is executed. Then, the evaluation value measurement area is regenerated to calculate the evaluation value,
The calculated evaluation value is corrected in advance based on the reflected light information detected in the evaluation value measurement area before recording, and the recording laser power is adjusted so that the corrected evaluation value matches a preset target value. The optical drive device according to claim 3, wherein control is performed.   The optical drive apparatus according to claim 4, wherein the control unit calculates a β value as the evaluation value. The control unit
Reproduction obtained from the result of the reflected light detection operation executed in advance in the evaluation value measurement area before recording the evaluation value as the β value obtained by reproducing the evaluation value measurement area after recording on the WOPC area The optical drive device according to claim 5, wherein correction is performed based on an amplitude level of an AC component of the signal. The control unit
The evaluation value as the β value obtained by executing recording and reproduction for the evaluation value measurement area in the WOPC area is obtained from the result of the reflected light detection operation executed in advance in the evaluation value measurement area before recording. The optical drive device according to claim 5, wherein correction is performed based on an amplitude level of a DC component of the reproduced signal. The control unit
As a result of the reflected light detection operation in which the value of the numerator of the β value obtained by executing the recording and reproduction for the evaluation value measurement area in the WOPC area is previously executed in the evaluation value measurement area before recording. The optical drive device according to claim 6 or 7, wherein the β value is corrected by changing in accordance with the amplitude level of the AC component or the DC component of the reproduction signal obtained from the above. The control unit
AC component of the reproduction signal obtained from the result of the reflected light detection operation executed in advance in the evaluation value measurement area before recording the β value obtained by reproducing the evaluation value measurement area after recording on the WOPC area The optical drive device according to claim 6, wherein the correction is performed in accordance with a ratio between a predetermined amplitude level or a reference level set in advance. The control unit
When executing the initial OPC in the OPC area set outside the user data area of the optical recording medium,
Each test section in the initial OPC section in which the reflected light detection operation is executed in advance in the pre-recording area in the OPC area to acquire the AC component or DC component amplitude level of the reproduction signal, and then the initial OPC is performed. The recording laser power is sequentially changed with respect to the recording and reproduction of the test signal is executed to calculate the β value for each test section, and the optimum recording laser power is determined based on the calculated β value,
Among the test sections, the evaluation value as the β value obtained in the test section where recording was performed under the setting of the determined recording laser power is the value of the reproduction signal obtained in advance in the pre-recording area. The optical drive apparatus according to claim 8, wherein correction is performed based on an amplitude level of an AC component or a DC component, and the corrected evaluation value is set as the target value. The control unit
The peak level and the bottom level of the AC component of the reproduction signal obtained in the test section where recording was performed under the setting of the recording laser power determined at the time of the initial OPC are Top Lv and Bottom Lv, respectively. When the peak level and bottom level of the AC component of the reproduction signal obtained in advance in the previous region are PreRec Top Lv and PreRec Bottom Lv,

{(Top Lv + Bottom Lv) −a (PreRec Top Lv−PreRec Bottom Lv) + b} / (Top Lv−Bottom Lv) [Formula I]

(However, in [Formula I], a and b are preset coefficients) to correct the β value, set the corrected β value as the target value,
At the time of the WOPC, the peak value and the bottom level of the AC component of the reproduction signal obtained by reproducing the evaluation value measurement area in the recorded state are set to Top Lv and Bottom Lv, respectively, and the evaluation value measurement before recording is performed. When the peak level and the bottom level of the AC component of the reproduction signal obtained from the result of the reflected light detection operation executed in advance in the region are set to PreRec Top Lv and PreRec Bottom Lv, respectively, the calculation according to [Expression I] is performed. 11. The optical drive according to claim 10, wherein the β value obtained in the evaluation value measurement region is corrected, and recording laser power adjustment control is performed so that the value obtained by correcting the β value matches the target value. apparatus. The control unit
When the initial OPC is executed in the OPC area set outside the user data area of the optical recording medium, the reflected light detection operation is executed in advance in the pre-recording area in the OPC area, and the reproduction signal AC After acquiring the amplitude level of the component or DC component, setting the AC component or DC component amplitude level of the acquired reproduction signal as the reference level, each test interval in the initial OPC interval in which the initial OPC is performed thereafter The recording laser power is sequentially changed with respect to the recording and reproduction of the test signal is executed to calculate the β value for each test section, and the optimum recording laser power is determined based on the calculated β value,
At the time of the WOPC, the β value obtained by executing recording and reproduction for the evaluation value measurement area in the WOPC area is obtained from the result of the reflected light detection operation executed in advance in the evaluation value measurement area before recording. Correction according to the ratio of the AC component amplitude level or DC component amplitude level of the reproduced signal to the reference level, and adjustment control of the recording laser power so that the corrected β value matches the target value The optical drive device according to claim 9. The control unit
At the time of the initial OPC, the top level of the DC component of the reproduction signal obtained in advance in the pre-recording area in the OPC area is set as the reference level, and
At the time of the WOPC, the reference level set at the time of the initial OPC is PreRec DC Top Lv Std, and the peak level of the DC component of the reproduction signal obtained in advance in the evaluation value measurement area before recording at the time of the WOPC is PreRec DC Top Lv

β × {c × ((PreRec DC Top Lv Std / PreRec DC Top Lv) −1) +1} [Formula II]

(Where [c] is a preset coefficient in [Formula II]), the β value obtained in the evaluation value measurement region is corrected, and the value obtained by correcting the β value matches the target value. The optical drive device according to claim 12, wherein adjustment control of recording laser power is performed. Recording parameters of an optical drive device comprising a recording unit that records information by irradiating the optical recording medium with laser light, and a reflected light detecting unit that detects reflected light of the laser light irradiated onto the optical recording medium An adjustment method,
Before the recording operation is performed on the pre-recording area of the optical recording medium, the reflected light detection operation is executed in advance, and the recording parameter adjustment control in the recording unit is performed based on the reflected light information detected thereby. Parameter adjustment method.