JP2006127568A - Recording condition deciding method, recording method, program and recording medium, and optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decide an appropriate recording condition when the information multi-valued to have ternary or more is recorded on the optical disk. <P>SOLUTION: Test data including a data row having at least one of consecutive multi-valued data forming a recording mark on a recording surface among M kinds of multi-valued data, are written on trial (steps 621-633) on a test writing area while changing stepwise a recording pulse width. Then, the test writing area is reproduced (step 641), and an inclination of a straight line connecting a plurality of reproduction signals corresponding to the same consecutive multi-valued data in the data row is obtained (steps 643-651) for every recording pulse width, and the recording pulse width of which the inclination of this straight line is corresponded to 0, is set as the optimum recording pulse width (steps 653, 655). Thus, an excess or deficiency of heat quantity can be suppressed since the appropriate heat quantity can be supplied to the recording surface even though the consecutive same multi-valued data are included in the information to be recorded on the recording surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a recording condition determination method, a recording method, a program and a recording medium, and an optical disc apparatus. More specifically, the present invention relates to a recording for determining recording conditions when information multi-valued into three or more values is recorded on an optical disc. The present invention relates to a condition determination method, a recording method for recording information multi-valued into three or more values on an optical disc, an optical disc apparatus, a program used in the optical disc apparatus, and a recording medium on which the program is recorded.

  In recent years, with the advancement of digital technology and the improvement of data compression technology, CD (compact disc), CD as a medium for recording information such as music, movies, photos and computer software (hereinafter also referred to as “content”) An optical disc such as a DVD (digital versatile disc) that can record data equivalent to about 7 times the data on a disc having the same diameter as a CD has been attracting attention. The optical disk device to be used has become widespread.

  In this optical disc apparatus, laser light is emitted from a light source, information is recorded by forming a minute spot on a recording layer of an optical disc on which spiral or concentric tracks are formed, and based on reflected light from the recording layer. Information is reproduced.

  In an optical disc, information is recorded by the lengths and combinations of marks and spaces having different reflectivities. In this case, the information is converted (binarized) into a combination of two types of numerical values (binary) of 0 and 1, and written on the optical disc. Hereinafter, such a recording method is referred to as a binary recording method.

  For example, rewritable optical discs such as CD-RW (CD-rewritable), DVD-RW (DVD-rewritable), and DVD + RW (DVD + rewritable) containing a special alloy in the recording layer (hereinafter also referred to as “phase change disc” for convenience) Then, when forming the mark, the special alloy is heated to the first temperature and then rapidly cooled to be in an amorphous state. On the other hand, when forming the space, the special alloy is heated to the second temperature (<first temperature) and then gradually cooled to a crystalline state. As a result, the reflectance of the mark is lower than that of the space. The temperature control of such a special alloy is performed by controlling the light emission power of the laser beam. In particular, when forming a mark, in order to reduce the change in heat distribution due to the preceding and following marks and spaces, the pulse shape of the light emission power is determined based on a rule (method) related to the pulse shape of the light emission power called a recording strategy. It is set.

  In the optical disk apparatus, a test called a PCA (Power Calibration Area) set in advance prior to information recording is performed so that a mark and a space of a target length are formed at the target position of the optical disk, respectively, during recording. Trial writing is performed in the writing area to obtain the optimum recording power (see, for example, Patent Document 1). This process is called an OPC (Optimum Power Control) process.

  By the way, the information amount of the content tends to increase year by year, and further increase of the information amount that can be recorded on one optical disk is expected. One way to increase the amount of information that can be recorded on an optical disc is to convert the information into a combination of three or more numerical values and write it to the optical disc. Has been done. Hereinafter, converting information into a combination of three or more types of numerical values is referred to as multi-value data, and multi-value data is referred to as multi-value data. In addition, such a recording method for recording information with multiple values is called a multi-value recording method. In this multilevel recording method, a track is virtually divided into a plurality of partial areas called cells of the same size, and the length of the track in the tangential direction differs depending on the multilevel data in each cell. It is considered to form a mark (record mark). Thereby, for example, in the phase change disk, the ratio of the amorphous state portion and the crystalline state portion in one cell differs according to the multi-value data, and the cell has a reflectivity according to the multi-value data. Will have.

  The multi-value recording method has characteristics that the recording linear density is higher than that of the binary recording method and the cell size is smaller than the spot diameter of the light spot, and therefore, intersymbol interference is likely to occur. Therefore, in the multi-value recording method, since the recording conditions greatly affect the recording quality more than the binary recording method, various recording methods for obtaining good recording quality have been proposed (see, for example, Patent Documents 2 to 5). ). However, in the recording methods disclosed in Patent Documents 2 to 5, when the cell size is further reduced and the recording speed is further increased, the shape of the recording mark is deformed with respect to the target shape and is not necessarily good. There was a risk that the recording quality would not be good.

Japanese Patent No. 3124721 JP-A-8-147695 JP-A-10-134353 Japanese Patent Laid-Open No. 11-25456 JP 2003-91822 A

  The present invention has been made under such circumstances. The first object of the present invention is a recording condition that can determine an appropriate recording condition for recording information multi-valued in three or more values on an optical disc. To provide a decision method.

  A second object of the present invention is to provide a recording method and an optical disc apparatus capable of recording information multi-valued into three or more values on an optical disc with high recording quality.

  A third object of the present invention is a program that can be executed by a computer for controlling an optical disk device and that can record information multi-valued in three or more values on an optical disk with high recording quality, and It is to provide a recording medium on which a program is recorded.

  As a result of earnest research on the cause of the deformation of the recording mark described above, the inventor is apt to cause a shortage of heat or an excessive amount of heat when the information recorded on the optical disc includes the same continuous multi-value data. When the heat amount is insufficient, the shape of the recording mark is reduced with respect to the target shape in the track direction, and when the heat amount is excessive, the shape of the recording mark is expanded with respect to the target shape in the track direction. I got the knowledge. The present invention has been made based on the new knowledge obtained by the inventors, and employs the following configuration.

  The invention according to claim 1 irradiates a recording surface of an optical disc with a pulsed laser beam including a recording pulse defined by a recording power and a recording pulse width for heating the recording surface, using an optical pickup device, A recording condition determination method for determining a condition for recording information represented by three or more M types of multilevel data having different signal levels of corresponding reproduction signals, wherein among the M types of multilevel data, , Stepwise changing the recording pulse width of test data including at least one data string in which multi-valued data in which recording marks are formed on the recording surface is continuous to a test writing area provided on the recording surface However, the first step of trial writing; reproducing the area where the test data was trial-written, and corresponding to the same continuous multi-value data in the data row for each recording pulse width A recording condition determining method comprising: seeking straight line connecting the plurality of reproduction signals, a second step and determining an optimum recording pulse width based on the slope of the straight line.

  According to this, test data including a data string in which at least one multi-value data in which a recording mark is formed on the recording surface among M kinds of multi-value data is continuous is provided on the recording surface. Trial writing is performed in the area while changing the recording pulse width stepwise (first step). Then, the area where the test data is written by trial is reproduced, and a straight line connecting a plurality of reproduction signals corresponding to the same continuous multi-valued data in the data string is obtained for each recording pulse width, and the slope of the straight line is obtained. Based on this, the optimum recording pulse width is determined (second step). In this case, even if the information recorded on the recording surface includes the same continuous multi-value data, an appropriate amount of heat can be supplied to the recording surface, resulting in insufficient heat or excessive heat. Can be suppressed. That is, it is possible to determine an appropriate recording condition for recording information multi-valued to three or more values on an optical disc.

  In this case, as in the recording condition determination method according to claim 2, the test data includes a first data string in which first multi-value data in which a recording mark is formed on the recording surface is continuous, When the second multi-value data in which the recording mark different from the first multi-value data is formed includes a continuous second data string, in the second step, each recording pulse width is In addition, a first straight line connecting reproduction signals corresponding to each first multi-value data in the first data sequence, and a reproduction signal corresponding to each second multi-value data in the second data sequence And determining the optimum recording pulse width for recording the first multi-value data based on the slope of the first line, and the slope of the second line. When recording the second multi-value data based on It may be able to determine the optimum recording pulse width.

  In this case, as in the recording condition determining method according to claim 3, the first multilevel data has a signal level of a reproduction signal corresponding to the first multilevel data of the M types of multilevel data. The signal level of the reproduction signal corresponding to the second multi-valued data is equal to or higher than the intermediate value of the signal levels of the M kinds of reproduction signals corresponding to the value-coded data. It may be less than the intermediate value.

  In each recording condition determining method according to any one of claims 1 to 3, as in the recording condition determining method according to claim 4, in the second step, a linear expression showing a relationship between the inclination and the recording pulse width. Can be obtained by an approximate calculation, and the recording pulse width corresponding to the slope of 0 can be obtained using the linear expression, and the recording pulse width can be determined as the optimum recording pulse width.

  In each of the recording condition determining methods according to claims 1 to 3, specific multi-valued data in which recording marks are not formed on the M types of multi-valued data as in the recording condition determining method according to claim 5 is provided. In the case where the test data further includes a specific data string in which the specific multilevel data is continuous, in the second step, the same continuous multilevel data in which the recording marks are formed A recording pulse width when a slope of a straight line connecting a plurality of reproduction signals corresponding to the same as a slope of a straight line connecting a plurality of reproduction signals corresponding to the continuous specific multilevel data in the specific data string is The optimum recording pulse width can be determined.

  6. In each of the recording condition determination methods according to claims 1 to 5, as in the recording condition determination method according to claim 6, the data string includes at least five identical multi-value data that are continuous. It can be.

  In each of the recording condition determination methods according to claims 1 to 6, as in the recording condition determination method according to claim 7, a third step of acquiring an optimum recording power prior to the first step is performed. In addition, in the first step, the test data can be test-written with the optimum recording power acquired in the third step.

  In this case, as in the recording condition determination method according to claim 8, prior to the first step, the M types of multi-valued data are obtained with the optimum recording power acquired in the third step. A fourth step of test writing the test data including M data strings each having the same multi-valued data continuous to the test writing region; and reproducing the region trial-written in the fourth step; First, a straight line connecting a plurality of reproduction signals corresponding to the same continuous multi-value data is obtained for each data string, and multi-value data in which the slope of the straight line is outside a preset allowable range is obtained. And in the first step, test data including a data string in which multi-value data out of the allowable range is continuous is written in the test writing area. it can.

  In each of the recording condition determining methods according to claims 1 to 6, as in the recording condition determining method according to claim 9, in the first step, a recommended value of the recording power recorded in advance on the optical disc is used. The test data can be test-written in the test-writing area.

  In each of the recording condition determination methods according to the first to ninth aspects, as in the recording condition determination method according to the tenth aspect, the optical disc may be an optical disc capable of rewriting recorded contents.

  The invention according to claim 11 irradiates the recording surface of the optical disc with a pulsed laser beam including a recording pulse defined by recording power and recording pulse width for heating the recording surface, using an optical pickup device, The recording condition determination according to any one of claims 1 to 10, wherein the recording method records information represented by three or more types of multi-value data having different signal levels of corresponding reproduction signals. The recording method includes a step of irradiating a pulsed laser beam including a recording pulse having a recording pulse width determined by the method and recording the information on an optical disc.

  According to this, since the pulsed laser beam including the recording pulse having the recording pulse width determined by the recording condition determining method according to any one of claims 1 to 10 is irradiated, the number is more than three values. It is possible to record the valuated information on the optical disc with high recording quality.

  According to a twelfth aspect of the present invention, a recording surface of an optical disc is irradiated with a pulsed laser beam defined by a recording power and a recording pulse width and including a recording pulse for heating the recording surface, and a corresponding reproduction signal Is a program for use in an optical disc apparatus capable of recording information represented by three or more M types of multi-value data having different signal levels, and of the M types of multi-value data, Test-write test data including at least one data string in which multi-valued data on which recording marks are formed is continuous in a test writing area provided on the recording surface while changing the recording pulse width stepwise. A first procedure; reproducing an area in which the test data is written on a trial basis, and a plurality of replays corresponding to the same continuous multi-value data in the data string for each recording pulse width; Is a program for executing a control computer of the optical disk apparatus; seeking straight line connecting the signal, and a second procedure for determining an optimum recording pulse width based on the slope of the straight line.

  According to this, when the program of the present invention is loaded into a predetermined memory and the start address is set in the program counter, the control computer of the optical disc apparatus has a record mark among the M types of multi-value data. Test data including a data string in which at least one multi-value data to be formed is continuously written in a test writing area provided on the recording surface while changing the recording pulse width stepwise. Then, the area in which the test data is written by trial is reproduced, and a straight line connecting a plurality of reproduction signals corresponding to the same continuous multi-valued data in the data string is obtained for each recording pulse width, and based on the inclination of the straight line To determine the optimum recording pulse width. That is, according to the program of the present invention, it is possible to cause the computer for controlling the optical disc apparatus to execute the recording condition determining method according to the first aspect of the present invention, whereby information multi-valued to three or more values is obtained. Can be recorded on the optical disc with high recording quality.

  In this case, as in the program according to claim 13, the test data includes a first data string in which first multi-value data in which a recording mark is formed on the recording surface is continuous, and the first data In the case where the second multi-value data in which the recording marks different from the multi-value data are formed includes a continuous second data string, the test data is written by trial as the second procedure. A first straight line connecting reproduction signals corresponding to each first multi-valued data in the first data sequence and each second in the second data sequence for reproducing the area and for each recording pulse width. Second straight lines connecting the reproduction signals corresponding to the multi-valued data are respectively determined, and an optimum recording pulse width for recording the first multi-valued data is determined based on the slope of the first straight line. And the slope of the second straight line The procedure for determining an optimum recording pulse width when recording the second multilevel data based, may be to be executed by the control computer.

  In this case, as in the program according to claim 14, the first multi-value data has a signal level of a reproduction signal corresponding to the first multi-value data and the M types of multi-value data. Are equal to or higher than the intermediate value of the signal levels of the M types of reproduction signals, and the second multilevel data has the signal level of the reproduction signal corresponding to the second multilevel data being the intermediate value. It can be less than.

  In each program according to claims 12 to 14, as in the program according to claim 15, as the second procedure, a linear expression indicating a relationship between the slope and the recording pulse width is obtained by an approximate calculation, It is possible to cause the control computer to execute a procedure of acquiring a recording pulse width corresponding to the slope of 0 using the linear expression and determining the recording pulse width as an optimum recording pulse width.

  In each of the programs according to claims 12 to 14, as in the program according to claim 16, the M types of multi-value data include specific multi-value data in which no recording mark is formed, and the test The data further includes a specific data string in which the specific multilevel data is continuous, and as the second procedure, a plurality of reproduction signals corresponding to the same continuous multilevel data on which the recording marks are formed Is determined to be the optimum recording pulse width when the slope of the straight line connecting the two coincides with the slope of the straight line connecting the plurality of reproduction signals corresponding to the continuous specific multilevel data in the specific data string This procedure can be executed by the control computer.

  In each of the programs according to claims 12 to 16, a third procedure for acquiring an optimum recording power prior to the first procedure as in the program according to claim 17 is further performed on the control computer. As the first procedure, the control computer can be caused to execute a procedure for trial writing the test data with the optimum recording power acquired in the third procedure.

  In this case, as in the program according to claim 18, the same multi-valued data for the M types of multi-valued data is obtained with the optimum recording power acquired in the third procedure prior to the first procedure. A fourth procedure for trial writing test data including M data strings each of which is converted into valuated data in the trial writing area; and reproducing the area trial-written in the fourth procedure; Fifth procedure for obtaining straight lines connecting a plurality of reproduction signals corresponding to the same continuous multi-value data every time and obtaining multi-value data in which the slope of the straight line is outside a preset allowable range The control computer further executes, and as the first procedure, a procedure for trial writing test data including a data string in which multi-value data out of the allowable range is continuous in the trial writing area. It may be to be executed by the serial control computer.

  The program according to any one of claims 12 to 16, wherein the test data is tested with the recommended value of the recording power recorded on the optical disc as the first procedure, as in the program according to claim 19. It is possible to cause the control computer to execute a test writing procedure in the writing area.

  A twentieth aspect of the invention is a computer-readable recording medium on which the program according to any one of the twelfth to nineteenth aspects is recorded.

  According to this, since the program according to any one of claims 12 to 19 is recorded, when the computer executes the information, the information multi-valued to three or more values is recorded with high recording quality. Can be recorded.

  According to a twenty-first aspect of the present invention, a recording surface of an optical disc is irradiated with a pulsed laser beam defined by a recording power and a recording pulse width and including a recording pulse for heating the recording surface, and a signal of a corresponding reproduction signal is emitted. 20. An optical disc apparatus capable of recording information represented by three or more M types of multi-value data having different levels, and a memory in which the program according to any one of claims 12 to 19 is recorded; A control computer for determining an optimum recording pulse width in accordance with the program recorded in the memory; an optical pickup device for emitting the laser beam; and a pulsed laser including a recording pulse of the determined recording pulse width And a processing device that records the information by irradiating the recording surface with light through the optical pickup device.

  According to this, the program according to any one of claims 12 to 19 recorded in the memory is executed by the control computer, and the optimum recording pulse width is determined. Then, the processing device irradiates the recording surface with a pulsed laser beam including a recording pulse having the determined recording pulse width via the optical pickup device, and information is recorded. In this case, even if the same multi-valued data is included in the information recorded on the recording surface, since an appropriate amount of heat is supplied to the recording surface, the occurrence of insufficient heat or excessive heat is suppressed. As a result, it is possible to record information multi-valued to three or more values on an optical disc with high recording quality.

  According to a twenty-second aspect of the present invention, the recording surface of the optical disc is irradiated with a pulsed laser beam defined by a recording power and a recording pulse width and including a recording pulse for heating the recording surface. An optical disc device capable of recording information expressed by three or more M types of multilevel data having different levels, the optical pickup device emitting the laser beam; and the M types of multilevel data Test data including a data string in which at least one multi-value data on which a recording mark is formed is continuous is written on the test writing area provided on the recording surface while changing the recording pulse width stepwise. Thereafter, the test writing area is reproduced, and a slope of a straight line connecting a plurality of reproduction signals corresponding to the same continuous multilevel data in the data string obtained for each recording pulse width is obtained. A control device for determining an optimum recording pulse width based on the information; irradiating the recording surface with a pulsed laser beam including a recording pulse of the determined recording pulse width via the optical pickup device; An optical disk device comprising: a processing device for recording

  According to this, a test data including a data string in which at least one multi-value data on which a recording mark is formed among M types of multi-value data is continuously provided by the control device is provided on the recording surface. After trial writing while gradually changing the recording pulse width in the writing area, the trial writing area is reproduced, and a plurality of data corresponding to the same continuous multi-value data in the data string obtained for each recording pulse width Based on the slope of the straight line connecting the reproduction signals, the optimum recording pulse width is determined. Then, the processing device irradiates the recording surface with a pulsed laser beam including a recording pulse having the determined recording pulse width via the optical pickup device, and information is recorded. In this case, even if the same multi-valued data is included in the information recorded on the recording surface, since an appropriate amount of heat is supplied to the recording surface, the occurrence of insufficient heat or excessive heat is suppressed. As a result, it is possible to record information multi-valued to three or more values on an optical disc with high recording quality.

  In this case, as in the optical disk device according to claim 23, the test data includes a first continuous multi-value data in which recording marks are formed among the M types of multi-value data. In the case where the control device includes a data string and a second data string in which second multi-valued data in which recording marks different from the first multi-valued data are formed are continuous, the control device, An optimum recording pulse width for recording the first multi-value data is determined based on the slope of the reproduction signal corresponding to one data string, and the slope of the reproduction signal corresponding to the second data string The optimum recording pulse width when recording the second multi-value data can be determined based on the above.

  In this case, as in the optical disc apparatus according to claim 24, the first multi-value data has a reproduction signal level corresponding to the first multi-value data having the M types of multi-value data. The second multi-value data has a signal level of the reproduction signal corresponding to the second multi-valued data that is equal to or higher than the intermediate value of the signal levels of M types of reproduction signals corresponding to the data. It can be less than the value.

  In each of the optical disk devices according to claims 22 to 24, as in the optical disk device according to claim 25, the control device obtains a linear expression indicating a relationship between the inclination and the recording pulse width by an approximate calculation, Using the linear expression, a recording pulse width corresponding to the inclination of 0 can be acquired, and the recording pulse width can be determined as the optimum recording pulse width.

  In each of the optical disk devices according to claims 22 to 24, as in the optical disk device according to claim 26, the M types of multi-value data include specific multi-value data in which a recording mark is not formed, When the test data further includes a specific data string in which the specific multi-value data is continuous, the control device may include a plurality of data corresponding to the same continuous multi-value data on which the recording mark is formed. The optimum recording pulse width is the recording pulse width when the inclination of the straight line connecting the reproduction signals matches the inclination of the straight line connecting the plurality of reproduction signals corresponding to the continuous specific multilevel data in the specific data string. Can be determined.

  In each of the optical disk devices according to claims 22 to 26, as in the optical disk device according to claim 27, the control device acquires an optimum recording power prior to trial writing of the test data, The test data can be trial-written with an optimum recording power.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of an optical disc apparatus 20 according to an embodiment of the present invention.

  An optical disk device 20 shown in FIG. 1 includes a spindle motor 22 for rotating the optical disk 15, an optical pickup device 23, a seek motor 21 for driving the optical pickup device 23 in the sledge direction, a laser control circuit 24, An encoder 25, a drive control circuit 26, a reproduction signal processing circuit 28, a buffer RAM 34, a buffer manager 37, an interface 38, a flash memory 39, a CPU 40, a RAM 41, and the like are provided. Note that the arrows in FIG. 1 indicate the flow of typical signals and information, and do not represent the entire connection relationship of each block. In addition, the optical disc apparatus 20 corresponds to a multi-value recording method, and in this embodiment, as an example, recording data (information) is converted into a combination of eight kinds of numerical values (0 to 7). That is, it is assumed to be multi-valued to 8 values (0 to 7).

  The optical disk 15 is, for example, a phase change disk corresponding to a wavelength of about 405 nm. This optical disk 15 has a recording layer containing a Ge—Sb—Te alloy (special alloy). In this recording layer, spiral tracks are formed by wobbling periodically. As an example, the track pitch is set to about 0.44 μm.

  The optical pickup device 23 is a device for irradiating the recording layer of the optical disk 15 rotated by the spindle motor 22 with laser light and receiving reflected light from the recording layer. As shown in FIG. 2 as an example, the optical pickup device 23 includes a light source LD, a collimating lens 52, a polarizing beam splitter 54, a rising mirror 53, a quarter wavelength plate 55, an objective lens 60, a detection lens 58, a light receiving element. And a drive system (not shown).

  The light source LD is a semiconductor laser that emits a linearly polarized light beam having a wavelength of about 405 nm (here, S-polarized light as an example). In the present embodiment, the maximum intensity emission direction of the light beam emitted from the light source LD is the + X direction.

  The collimating lens 52 is disposed on the + X side of the light source LD, and makes the light beam emitted from the light source LD substantially parallel light.

  The polarization beam splitter 54 is disposed on the + X side of the collimating lens 52 and branches the light beam (return light beam) reflected by the optical disk 15 in the −Z direction. Here, as an example, the polarization beam splitter 54 has a high transmittance for S-polarized light and a high reflectance for P-polarized light.

  The raising mirror 53 is disposed on the + X side of the polarizing beam splitter 54 and bends the optical path of the light beam transmitted through the polarizing beam splitter 54 in the + Z direction. The quarter wavelength plate 55 is disposed on the + Z side of the rising mirror 53, and the objective lens 60 is disposed on the + Z side of the quarter wavelength plate 55. In this embodiment, as an example, it is assumed that the numerical aperture NA of the objective lens 60 is 0.65, and the spot diameter of the light spot formed on the recording layer is about 0.54 μm.

  The detection lens 58 is disposed on the −Z side of the polarization beam splitter 54 and condenses the return light beam branched in the −Z direction by the polarization beam splitter 54 on the light receiving surface of the light receiver PD. The light receiver PD has a plurality of light receiving elements (a plurality of light receiving elements that output signals including wobble signal information, reproduction data information, focus error information, track error information, radial tilt information, etc.) in the same manner as a normal three-axis drive type optical pickup device. Or a light receiving area). The radial tilt refers to the tilt of the recording layer with respect to the objective lens 60 with respect to the radial direction of the optical disc 15.

  The drive system (not shown) is a focusing actuator for minutely driving the objective lens 60 in the focus direction that is the optical axis direction of the objective lens 60, and the objective lens 60 in the tracking direction that is perpendicular to the tangential direction of the track. It includes a tracking actuator for minute driving, a radial tilt actuator for rotating the objective lens 60 about a tangential axis of the track, and the like.

  The operation of the optical pickup device 23 configured as described above will be briefly described. The light beam of linearly polarized light (here, S-polarized light) emitted from the light source LD is converted into substantially parallel light by the collimator lens 52 and then polarized. The light enters the beam splitter 54. The light beam transmitted through the polarization beam splitter 54 is bent by the rising mirror 53 and is circularly polarized by the quarter-wave plate 55, and then is minutely applied to the recording layer of the optical disk 15 through the objective lens 60. It is collected as a spot.

  The reflected light reflected by the recording layer of the optical disk 15 becomes circularly polarized light opposite to the outward path, and is converted into substantially parallel light again by the objective lens 60 as a return beam, and linearly polarized light orthogonal to the outward path by the quarter wavelength plate 55 (here) Is P-polarized light). Then, the return light beam that has passed through the quarter-wave plate 55 enters the polarization beam splitter 54 via the rising mirror 53. Further, the return light beam branched in the −Z direction by the polarization beam splitter 54 is collected by the detection lens 58 and received by the light receiver PD. A plurality of light receiving elements (or light receiving regions) constituting the light receiver PD respectively generate photoelectric conversion signals corresponding to the amount of received light, and output them to the reproduction signal processing circuit 28.

  Returning to FIG. 1, the reproduction signal processing circuit 28 is based on the output signal (a plurality of photoelectric conversion signals) of the light receiver PD, servo signals (focus error signal, track error signal, radial tilt signal, etc.), address information. Various clocks (recording clock, reproduction clock, etc.), RF signal (reproduction signal), etc. are acquired. Further, the reproduction signal processing circuit 28 performs decoding processing, error detection processing, and the like on the RF signal. When an error is detected, the reproduction signal processing circuit 28 performs error correction processing, and then plays back the buffer via the buffer manager 37 as reproduction data. Store in the RAM 34. Further, the reproduction signal processing circuit 28 samples the RF signal in accordance with an instruction from the CPU 40, AD converts the result, and notifies the CPU 40 of the result.

  The drive control circuit 26 generates a drive signal for the tracking actuator for correcting the positional deviation of the objective lens 60 with respect to the tracking direction based on the track error signal from the reproduction signal processing circuit 28, and generates a focus error signal. Based on this, a driving signal for the focusing actuator for correcting the focus shift of the objective lens 60 is generated. Further, the drive control circuit 26 generates a drive signal for the radial tilt actuator for correcting the radial tilt based on the radial tilt signal from the reproduction signal processing circuit 28. Each drive signal generated here is output to the optical pickup device 23. Thereby, tracking control, focus control, and radial tilt control are performed.

  Furthermore, the drive control circuit 26 generates a drive signal for driving the seek motor 21 and a drive signal for driving the spindle motor 22 based on an instruction from the CPU 40. Each drive signal is output to the seek motor 21 and the spindle motor 22, respectively.

  The buffer RAM 34 temporarily stores data to be recorded on the optical disc 15 (recording data), data reproduced from the optical disc 15 (reproduction data), and the like. Data input / output to / from the buffer RAM 34 is managed by the buffer manager 37.

  The encoder 25 takes out the recording data stored in the buffer RAM 34 through the buffer manager 37 based on an instruction from the CPU 40, modulates the data, adds an error correction code, and the like, and writes a signal to the optical disc 15. Is generated. The write signal generated here is output to the laser control circuit 24.

  The laser control circuit 24 controls the light emission power of the light source LD. For example, at the time of recording, a drive signal for the light source LD is generated by the laser control circuit 24 based on the write signal, recording clock, recording conditions, light emission characteristics of the light source LD, and the like.

  The interface 38 is a bidirectional communication interface with a host device 90 (for example, a personal computer), and is a standard interface such as ATAPI (AT Attachment Packet Interface), SCSI (Small Computer System Interface), and USB (Universal Serial Bus). It is compliant.

  The flash memory 39 includes a program area and a data area. In the program area, various programs including a program according to the present invention described by a code readable by the CPU 40 are stored. The data area stores the light emission characteristics of the light source LD, recording conditions, and the like.

  The CPU 40 controls the operation of each unit in accordance with a program stored in the program area of the flash memory 39 and stores data necessary for control in the RAM 41 and the buffer RAM 34.

<Multi-value recording method>
Next, the multi-value recording method in the optical disc apparatus 20 configured as described above will be described. As shown in FIG. 3 as an example, the track of the optical disk 15 is virtually divided into a plurality of regions (cells) every predetermined length (here, about 0.24 μm) in the tangential direction of the track. The One multi-value data is stored in one cell. When the multi-value data (m) is 1 to 7, a recording mark (amorphous region) having a length corresponding to the value is formed at the center of the cell. When m is 0, no recording mark is formed. That is, the multi-value data 0 is specific multi-value data. The distance between the centers of adjacent cells is called a cell period (Tc).

  In the portion where the recording mark is formed, the reflectivity of the laser beam decreases as the area of the recording mark increases. Therefore, as shown in FIG. 4 as an example, the intensity of the returning light beam (reflected light intensity) is the recording mark. The larger the area, the lower. Therefore, the reproduction signal (RF signal) generated from the laser beam reflected by the recording surface of the optical disc has a maximum level when m = 0 and a minimum level when m = 7. Here, as shown in FIG. 5 as an example, the target value (target level) of the signal level of the reproduction signal (hereinafter also referred to as “reproduction signal level”) is I0 when m = 0, and I1 when m = 1. , M = 2, I2, m = 3, I3, m = 4, I4, m = 5, I5, m = 6, I6, m = 7, I7. Therefore, I0-I7 is the target dynamic range (Dm). Here, as an example, Dm for I0 is 0.63 (63%). Further, the change in reproduction signal level (hereinafter also referred to as “detection window”) kw when m changes by 1 is Dm / 7, which is 0.09 (9%) for I0. Further, (I0 + I7) / 2 is an intermediate value of the reproduction signal level.

《Recording strategy》
Here, a recording strategy in the multi-value recording method will be described.

  The light emission power of the light source LD when the recording mark is formed on the optical disk 15 changes in a pulse shape according to the multi-value data. As shown in FIG. 6 as an example, the light emission pulse includes three pulses (recording pulse Wp, cooling pulse Cp, and erasing pulse Ep) for each cell. The light emission power at the recording pulse Wp is called the recording power (Wp), the light emission time is called the recording pulse width (Ton), the light emission power at the cooling pulse Cp is the cooling power (Pc), and the light emission The time is called a cooling pulse width (Toff), and the light emission power at the erase pulse Ep is called an erase power (Pe). The magnitude relationship between the light emission powers is Pw> Pe> Pc. The special alloy in the recording layer is melted by the recording pulse Wp, rapidly cooled by the cooling pulse Cp to be in an amorphous state (recording mark), and gradually cooled by the erasing pulse Ep to be in a crystalline state (also called “recording space”). Become.

  The erasing power Pe is a power obtained by multiplying the recording power Pw by a constant ε (usually about 0.5). When the rising timing of the recording pulse Wp is Ta, the falling timing is Tb, and the rising timing of the erasing pulse Ep is Td, the recording pulse width Ton = Tb-Ta and the cooling pulse width Toff = Td-Tb are obtained. The recommended values of the recording power Pw, the cooling power Pc, the constants ε, Ta, Tb, and Td on the optical disc 15 are recorded on the optical disc 15 as part of the preformat information. These default values are stored in the flash memory 39. Therefore, when the optical disk 15 is set in the optical disk apparatus 20, the recommended values of the recording power Pw, the cooling power Pc, the constants ε, Ta, Tb, and Td are read from the optical disk 15 and stored in the RAM 41. If the latest information of the recommended value is recorded other than the preformat information, the latest information is stored in the RAM 41.

<Recording process>
Next, a process (recording process) when the optical disc apparatus 20 configured as described above receives a recording request command from the host apparatus 90 will be described with reference to FIG. The flowchart in FIG. 7 corresponds to a series of processing algorithms executed by the CPU 40.

  When a recording request command is received from the host device 90, the top address of a program (hereinafter referred to as “recording processing program”) corresponding to the flowchart of FIG. 7 stored in the program area of the flash memory 39 is set in the program counter of the CPU 40. Then, the recording process starts. Here, it is assumed that the linear velocity of recording / reproducing is 6 m / s, the recording clock cycle is 2.7 ns, and the cell cycle Tc corresponds to 16 recording clocks.

  In the first step 401, the recommended values of the recording power Pw, cooling power Pc, constants ε, Ta, Tb, and Td in the optical disc 15 stored in the RAM 41 are acquired.

  In the next step 403, processing for acquiring the optimum recording power (hereinafter abbreviated as “optimum recording power acquisition processing”) is performed. Even when recording is performed under the recommended recording conditions, the signal level of the reproduction signal may not reach the target level, as shown in FIG. 8B as an example, depending on the characteristics of the optical disc apparatus. Therefore, as an example, as shown in FIG. 8A, first, the optimum recording power is acquired so that the signal level of the reproduction signal becomes the target level. Details of the processing here will be described later.

  In the next step 405, a process of acquiring an optimal recording pulse width for the optimal recording power acquired in the optimal recording power acquisition process (hereinafter abbreviated as “optimal recording pulse width acquisition process”) is performed. Details of the processing here will be described later.

  In the next step 407, the optimum recording power acquired in the optimum recording power acquisition process and the optimum recording pulse width obtained in the optimum recording pulse width acquisition process are recorded on the optical disc 15. Therefore, when the optical disk 15 is set next time, the recording power and the recording pulse width recorded here become their recommended values.

  In the next step 409, the recording condition is set using the optimum recording power and the optimum recording pulse width. The recording conditions set here are output to the laser control circuit 24.

  In the next step 411, the drive control circuit 26 is instructed to form a light spot in the vicinity of the target position corresponding to the address specified by the recording request command. Thereby, a seek operation is performed. If the seek operation is unnecessary, the process here is skipped.

  In the next step 413, recording is permitted. Thereby, recording on the optical disk 15 is started via the encoder 25, the laser control circuit 24, and the optical pickup device 23. Here, the recording layer of the optical disk 15 is irradiated with a pulsed laser beam including a recording pulse having an optimal recording power and an optimal recording pulse width.

  In the next step 415, it is determined whether or not the recording is completed. If it is not completed, the determination here is denied and the determination is made again after a predetermined time has elapsed. If completed, the determination here is affirmed and the recording process is terminated.

<< Optimal recording power acquisition process >>
Details of the optimum recording power acquisition process will be described with reference to the flowchart of FIG. Here, as an example, it is assumed that the recommended value of the recording power (hereinafter also referred to as “recommended recording power”) is 8 mW.

  In the first step 501, one of the γ method and the linear method is selected as a method for obtaining the optimum recording power. Here, it is assumed that the linear method is selected as an example. Note that the user can specify which method to select via the host device 90. Further, it may be selected on the optical disc apparatus 20 side according to the type of the optical disc. Alternatively, when the recommended method is recorded as one of the preformat information on the optical disc, the selection may be made on the optical disc apparatus 20 side based on the information.

In the next step 503, test data for trial writing is set. Here, as test data for the linear method, for all multi-value data (m = 0 to 7), a data string in which the same multi-value data is repeated five times is used as test data. That is, “00000111112122233333344444455555666667777” is the test data. Note that the number of the same multi-valued data is sufficient if the reproduction signal level that is not affected by intersymbol interference is equivalent to 3 cells. Therefore, the cells that are affected by intersymbol interference are added one by one before and after. Individual. The influence of intersymbol interference depends on the relationship between the spot diameter (the size at which the light intensity is 1 / e ^{2 of the} maximum value) and the size of the recording mark. Is determined by the size of That is, it is determined by the wavelength of the laser light emitted from the light source, the numerical aperture NA of the objective lens, and the cell linear density.

  In the next step 505, the number of trial writings (set to n) is set. In this embodiment, as an example, it is assumed that test writing is performed by changing the recording power (hereinafter referred to as “trial writing recording power Pt” for convenience) from 6 mW to 11 mW at 1 mW intervals when the test data is test-written. Therefore, n = 6 is set. In the trial writing, the recording power is such that the range of − (15 to 30)% to + (15 to 30)% of the recommended recording power (here, 8 mW) is divided into at least four. Is preferably carried out.

  In the next step 507, an initial value of the test writing recording power Pt is set. Here, 6 mW is set as the initial value of the test writing recording power Pt.

  In the next step 509, 0 is set as an initial value of a counter (referred to as CNT) for counting the number of trial writings.

  In the next step 511, test data is recorded in the minimum unit area (one sector) of the test writing area provided on the optical disk 15. The recommended values are used except for the recording power.

  In the next step 513, 1 is added to the value of the counter CNT.

  In the next step 515, it is determined whether or not the value of the counter CNT is n (here, 6). Here, since CNT = 1, the determination here is denied and the routine proceeds to step 517.

  In this step 517, an increment p (1 mW in this case) is added to the test writing recording power Pt to obtain a new test writing recording power Pt. Then, the process returns to step 511.

  Thereafter, the processes of steps 511 to 517 are repeated until the value of the counter CNT becomes equal to n. When the value of the counter CNT becomes equal to n, the determination in step 515 is affirmed and the process proceeds to step 519.

  In this step 519, the light emission power is set to a reproduction power of 0.5 mW, and the test writing area in which the test data is recorded is reproduced. Here, as shown in FIG. 10 as an example, a reproduction signal whose level changes substantially in a step shape is acquired.

  In the next step 521, the reproduction signal is sampled at a timing corresponding to the central portion of the cell via the reproduction signal processing circuit 28.

  In the next step 523, each sampling value is converted into a digital value (AD conversion) via the reproduction signal processing circuit 28. Here, a digital value corresponding to m = 0 corresponds to I (0), a digital value corresponding to m = 1 corresponds to I (1), a digital value corresponding to m = 2 corresponds to I (2), and m = 3. I (3), the digital value corresponding to m = 4 is I (4), the digital value corresponding to m = 5 is I (5), and the digital value corresponding to m = 6 is I (6) , M = 7 is the digital value I (7). In the following, when it is not necessary to distinguish each digital value, it is described as I (m) for convenience. Note that five digital values I (m) are obtained for one multivalued data, but in order to avoid the influence of intersymbol interference, the first and last values are not used and the remaining three average values are multivalued. The digital value I (m) of the digitized data m is assumed.

  In the next step 525, for each test writing recording power Pt, all digital values I (m) are normalized based on the following equation (1) to obtain a normalized value (referred to as Id (m)). (See FIG. 11). As a result, it is possible to correct a change in signal level caused by the type of the optical disk, the birefringence of the substrate, the intra-circumference variation in recording sensitivity, and the like.

  Id (m) = I (m) / I (0) × 100 (1)

  In the next step 527, it is determined whether or not the method for obtaining the optimum recording power is a linear method. Here, since the linear method is selected, the determination in step 527 is affirmed, and the process proceeds to step 529.

  In this step 529, as shown in FIG. 12 as an example, the relationship between the multi-value data m and the normalized value Id is expressed by the following approximate expression (2) for each test writing recording power Pt. Next, a quadratic regression operation is performed. Each coefficient (a, b, c) of each approximate expression obtained here is shown in FIG.

Id = a × m ² + b × m + c (2)

  In the next step 531, as shown in FIG. 14 as an example, a quadratic regression operation is performed so that the relationship between the test writing recording power Pt and the coefficient a is represented by the following approximate expression (3). In the present embodiment, A = 0.082, B = −0.88, and C = 1.71. That is, the following equation (4) is obtained.

a = A × Pt ² + B × Pt + C (3)
a = 0.082 × Pt ² −0.88 × Pt + 1.71 (4)

  In the next step 533, a solution of the above equation (4) is obtained. That is, the test writing recording power Pt is obtained so that the reproduction signal of the cell in which the same multi-valued data is continuous becomes flat. Here, two solutions (2.5 mW, 8.2 mW) are obtained.

  In the next step 535, the optimum recording power is determined. Here, as shown in FIG. 14, since a increases with an increase in Pt, the larger one of the above two solutions (8.2 mW) is set as the optimum recording power. The solution with the smaller difference from the recommended recording power (here 8 mW) may be set as the optimum recording power. Then, the optimum recording power acquisition process ends.

  If the γ method is selected as the method for obtaining the optimum recording power in step 501, the multi-value data 0 having the highest reproduction signal level and the multi-value having the smallest reproduction signal level are obtained in step 503. The data string “0000077777” composed of the digitized data 7 is the test data. Then, the determination at step 527 is negative, and the routine proceeds to step 541.

  In step 541, the modulation factor (referred to as Mod) is obtained based on the following equation (5). As an example, as shown in FIG. 15, the modulation degree Mod becomes substantially constant (saturates) as the test writing recording power Pt increases.

  Mod = {Id (7) −Id (0)} / Id (0) × 100 (5)

  In the next step 543, the rate of change of modulation degree Mod with respect to Pt (referred to as γ) is obtained based on the following equation (6).

  γ = (dMod / dPw) × (Pw / Mod) (6)

  In the next step 545, as shown in FIG. 16 as an example, an approximate expression indicating the relationship between γ and Pt is obtained.

  In the next step 547, Pt when γ becomes a predetermined value γt (1.2 in this case) is obtained from an approximate expression showing the relationship between γ and Pt. Here, Pt = 7.45 mW.

  In the next step 549, a value obtained by multiplying Pt when γ becomes a predetermined value γt by a predetermined coefficient k (here, 1.10), that is, 8.2 mW is set as the optimum recording power. The predetermined value γt and the predetermined coefficient k are recorded on the optical disc 15 as part of the preformat information. Then, the optimum recording power acquisition process ends.

<Optimal recording pulse width acquisition processing>
Here, details of the optimum recording pulse width acquisition processing will be described with reference to the flowchart of FIG.

  In the first step 601, the optimum recording power acquired in the optimum recording power acquisition process is set as the test writing recording power.

  In the next step 603, test data for test writing (hereinafter also referred to as “first test data”) is set. Here, for all multi-value data (m = 0 to 7), a data string in which the same multi-value data is repeated 5 times each is set as test data. That is, "00000111111122223233344344455555666667777" is the first test data.

  In the next step 605, the first test data is recorded in the minimum unit area (one sector) of the test writing area (hereinafter also referred to as “first test writing”). The recommended values are used except for the recording power.

  In the next step 607, the light emission power is set to a reproduction power of 0.5 mW, and the test writing area in which the first test data is recorded is reproduced.

  In the next step 609, the reproduction signal is sampled at a timing corresponding to the central portion of the cell via the reproduction signal processing circuit 28.

  In the next step 611, each sampling value is AD-converted via the reproduction signal processing circuit 28 to obtain a digital value I (m). Here, in order to avoid the influence of intersymbol interference, the digital values I (m) of the remaining three multilevel data m are validated without using the first and last values.

  In the next step 613, as shown in FIG. 18 as an example, all digital values I (m) are normalized based on the equation (1) to obtain a normalized value Id (m). Note that Pos indicates the number of cells among the five cells in which the same multi-value data is recorded (hereinafter also referred to as “cell position”), and Pos = 2 indicates the second cell. The cell, Pos = 3, indicates the third cell, and Pos = 4 indicates the fourth cell. Since the first cell and the fifth cell are affected by intersymbol interference, the reproduction signal corresponding to Pos = 1 and Pos = 5 is not used.

  In the next step 615, for each multi-valued data m, linear regression calculation is performed so that the relationship between the cell position Pos and the normalized value Id (m) is represented by the following approximate expression (7). The coefficients a and b are obtained (see FIG. 18).

  Id (m) = a × Pos + b (7)

  In the next step 617, an allowable range of a is obtained. Here, as shown in FIG. 19 as an example, the maximum allowable level fluctuation in three reproduction signals with Pos = 2 to 4 is set to 35% of the detection window kw. Therefore, the allowable range of the coefficient a is −1.6 (≈−9 × 0.35 / 2) <a <+1.6 (≈9 × 0.35 / 2). The maximum allowable value is not limited to 35% of the detection window kw, and may be changed according to the speed of trial writing, for example.

  In the next step 619, multi-value data m whose coefficient a is outside the allowable range is extracted. In FIG. 18, m = 7 and a = + 3.0.

  In the next step 621, test-written test data (hereinafter also referred to as “second test data”) including a data string in which the multi-value data m whose coefficient a is outside the allowable range is repeated five times is set. Here, “0000077777” is the second test data.

  In the next step 623, the number n of trial writings is set. In the present embodiment, as an example, the recording pulse width (hereinafter referred to as “trial writing recording pulse width Wt” for convenience) when test data is test-written is changed from 4.0 ns to 6.5 ns at 0.5 ns intervals. Test writing shall be performed. Therefore, n = 6 is set. Note that the trial write recording pulse width Wt is preferably changed so that the recommended value of the recording pulse width becomes substantially the center value.

  In the next step 625, an initial value of the test writing recording pulse width Wt is set. Here, 4.0 ns is set as the initial value of the test writing recording pulse width Wt.

  In the next step 627, 0 is set as the initial value of the counter CNT for counting the number of trial writings.

  In the next step 629, the second test data is recorded in the minimum unit area (one sector) of the test writing area (hereinafter also referred to as “second test writing”).

  In the next step 631, 1 is added to the value of the counter CNT.

  In the next step 633, it is determined whether or not the value of the counter CNT is n (here, 6). Here, since CNT = 1, the determination here is denied and the routine proceeds to step 635.

  In this step 635, an increment w (0.5 ns in this case) is added to the trial write recording pulse width Wt to obtain a new trial write recording pulse width Wt. Then, the process returns to step 629.

  Thereafter, steps 629 to 635 are repeated until the value of the counter CNT becomes equal to n. When the value of the counter CNT becomes equal to n, the determination at step 633 is affirmed and the routine proceeds to step 641.

  In this step 641, the light emission power is set to a reproduction power of 0.5 mW, and the test writing area in which the second test data is recorded is reproduced.

  In the next step 643, the reproduction signal is sampled at a timing corresponding to the center portion of the cell via the reproduction signal processing circuit 28.

  In the next step 645, each sampling value is AD-converted via the reproduction signal processing circuit 28 to obtain a digital value I (m). In order to avoid the influence of intersymbol interference, the digital values I (m) of the remaining three multilevel data are validated without using the first and last values.

  In the next step 647, as shown in FIG. 20 as an example, the digital value I (7) is normalized based on the equation (1) for each trial write recording pulse width Wt, and the normalized value Id (7 ) To get.

  In the next step 649, for each trial write recording pulse width Wt, the linear regression calculation is performed so that the relationship between the cell position Pos and the normalized value Id (7) is represented by the following approximate expression (8). As shown in FIG. 21 and FIG. 22 as an example, coefficients a ′ and b ′ are obtained. That is, a ′ is the slope (flatness) of a straight line connecting a plurality of reproduction signals corresponding to the same continuous multilevel data in the data string.

  Id (7) = a ′ × Pos + b ′ (8)

  In the next step 651, a linear regression operation is performed to obtain coefficients a ″ and b ″ so that the relationship between the coefficient a ′ and the test write recording pulse width Wt is represented by the following approximate expression (9). . In this embodiment, as shown in FIG. 23 as an example, a ″ = − 2.5 and b ″ = 14.9, and the following equation (10) is obtained.

a ′ = a ″ × Wt + b ″ (9)
a ′ = − 2.5 × Wt + 14.9 (10)

  In the next step 653, the trial write recording pulse width Wt corresponding to the coefficient a '= 0 is obtained. Here, when the solution of the above equation (10) is obtained, Wt = 6.0 ns.

  In the next step 655, an optimum recording pulse width is determined. Here, 6.0 ns is the optimum recording pulse width.

  Accordingly, as shown in FIG. 24 as an example, when multi-value data m = 7 is repeatedly recorded, the amount of heat is insufficient, and the recording mark has a shape in which the latter half is reduced with respect to the target shape. This can be suppressed.

  As is clear from the above description, in the optical disc device 20 according to the present embodiment, the processing device is configured by the encoder 25 and the laser control circuit 24. Further, the CPU 40 constitutes a control computer. Further, a control device is realized by the CPU 40 and a program executed by the CPU 40. That is, the control device is realized by the flowchart of FIG. Note that at least a part of the control device realized by processing according to the program by the CPU 40 may be configured by hardware, or all may be configured by hardware.

  In the present embodiment, among the programs stored in the flash memory 39 (memory), the recording processing program includes the program of the present invention. That is, the first procedure is configured by a program corresponding to the processing of steps 621 to 635 in FIG. 17, and the second procedure is configured by a program corresponding to the processing of steps 641 to 655 in FIG. Further, the third procedure is configured by the program corresponding to the processing of FIG. 9, the fourth procedure is configured by the program corresponding to the processing of steps 601 to 605 of FIG. 17, and the processing of steps 607 to 619 of FIG. The fifth procedure is configured by a program corresponding to the above.

  In the recording process, the recording condition determination method and the recording method according to the present invention are implemented. That is, the first process of the recording condition determination method is performed by the processes of steps 621 to 635 in FIG. 17, and the second process is performed by the processes of steps 641 to 655 in FIG. Further, the third step of the recording condition determination method is performed by the processing of FIG. 9, the fourth step is performed by the processing of steps 601 to 605 of FIG. 17, and the fifth step is performed by the processing of steps 607 to 619 of FIG. The process is implemented. Further, the recording process of the recording method is performed by the processing of steps 409 to 413 in FIG.

  As described above, according to the optical disc apparatus 20 according to the present embodiment, when the user data is represented by eight types (0 to 7) of multi-value data and recorded on the recording surface of the optical disc 15, the second Test data “0000077777” is written on the test writing area provided on the recording surface while changing the recording pulse width from 4.0 ns to 6.5 ns at intervals of 0.5 ns. Then, the area where the second test data is written on trial is reproduced, and the slope of a straight line connecting a plurality of reproduction signals corresponding to the continuous multi-value data 7 in the data string is obtained for each recording pulse width. Subsequently, a linear expression showing the relationship between the recording pulse width and the slope of the straight line is obtained by an approximate calculation, and the recording pulse width when the slope of the straight line becomes almost zero is calculated. Then, the calculated recording pulse width is determined as an optimum recording pulse width. As a result, even if the same multi-valued data is included in the information recorded on the recording surface, it is possible to supply an appropriate amount of heat to the recording surface, thereby suppressing the occurrence of insufficient heat or excessive heat. It becomes possible to do. That is, it is possible to determine an appropriate recording condition for recording information multi-valued to three or more values on an optical disc.

  Further, according to the present embodiment, prior to trial writing of the second test data, OPC (Optimum Power Control) processing is performed to obtain an optimum recording power. Then, the second test data is written by trial with the optimum recording power. Thereby, the optimum recording pulse width can be easily determined.

  In addition, according to the present embodiment, prior to trial writing of the second test data, the first test data “00000111122122233333444445555555666667777” is trial-written with the optimum recording power, and the slope of the reproduction signal for each multilevel data. Is determined to be within a predetermined allowable range, and the multi-value data 7 outside the allowable range is included in the second test data. Thereby, the optimum recording pulse width can be determined efficiently.

  In the above-described embodiment, the case where “0000077777” is used as the second test data in the optimum recording pulse width acquisition processing has been described. However, when the variation in the circumference of the optical disk 15 is small, “77777” is set. Second test data may be used. In this case, the normalization is not performed.

  In the above embodiment, the case where the coefficient a is outside the allowable range when m = 7 in the optimum recording pulse width acquisition process has been described. For example, as shown in FIG. 25, when m = 1, If the coefficient a is outside the allowable range, “0000011111” becomes the second test data in step 621. Then, in step 647, a normalized value Id (1) is obtained as shown in FIG. 26 as an example, and in step 649, as shown in FIG. 27 and FIG. 28 as an example, coefficients a ′ and b ′ is calculated. Further, in step 651, as shown in FIG. 29 as an example, a ″ = − 1.7 and b ″ = 7.9 are obtained, and in step 653, Wt≈4.5 ns. That is, the optimum recording pulse width is 4.5 ns. In this case, as shown in FIG. 30 as an example, when the multi-value data m = 1 is repeatedly recorded, the amount of heat becomes excessive, and the recording mark has a shape in which the latter half is expanded with respect to the target shape. Can be suppressed.

  In the above-described embodiment, the case where there is one m where the coefficient a is outside the allowable range in the optimum recording pulse width acquisition processing has been described. However, the present invention is not limited to this. For example, when m = 2 and m = 7 and the coefficient a is outside the allowable range, the second test data may be “00002222227777”. Note that m = 2 corresponds to a reproduction signal level equal to or higher than the intermediate value, and m = 7 corresponds to a reproduction signal level lower than the intermediate value.

  In the above embodiment, the case where the second test data is composed of the multi-value data 0 and the multi-value data whose coefficient a is outside the allowable range has been described. The same data string “00000111122122233333444445555555666667777” as the test data may be used as the second test data. In this case, in step 641, as shown in FIG. 31 as an example, a reproduction signal whose level changes stepwise is acquired. In step 649, a coefficient a 'is calculated for each multilevel data as shown in FIG. 32 as an example. Further, in step 651, a ″ and b ″ are calculated for each multilevel data. In step 653, Wt = 4.5 ns when m = 1 and 2, and Wt when m = 3 and 4. When W == 5.0 ns, m = 5 and 6, Wt = 5.5 ns, and when m = 7, Wt = 6.0 ns. In this case, as shown in the flowchart of FIG. 33, since the first trial writing can be omitted, the processing time in the optimum recording pulse width acquisition process can be shortened and the trial writing area can be efficiently used. Can be used well.

  In this case, when the optical phase difference (birefringence) in the optical disc and the variation in the circumference of the substrate thickness are large, the coefficient a ′ may be calculated for m = 0. The actual reproduction signal level may fluctuate in the reproduction signal level even if the multi-value data is the same due to the fluctuation in the circumference. Therefore, if there is a level fluctuation in the test writing area, the coefficient a 'has a certain shift (offset) with respect to all the multi-value data. However, since m = 0 does not include a cooling pulse, the reproduction signal level does not change depending on the recording pulse width Ton. That is, the coefficient a ′ obtained for m = 0 reflects only the above-described intra-circumference variation of the optical disc. Therefore, by calculating a solution Wt with which the coefficient a ′ is the same as the coefficient a ′ at m = 0 for each m (1 to 7), the optimum recording pulse width with corrected intra-circumference variation is obtained. Can be calculated.

  In the above-described embodiment, the case where the second test data is trial-written with the optimum recording power obtained by the OPC process has been described. The second test data may be written on a trial basis with the recommended recording power value. Thereby, the time required for the recording process can be shortened. Further, for example, when the latest recommended value of recording power is recorded on the optical disc separately from the preformat information, the second test data may be written by trial using the latest recommended value. If the recommended value of the recording power is not recorded on the optical disc, the second test data may be written by trial using the default value stored in the flash memory 39.

  In the above embodiment, the case where a Ge—Sb—Te alloy is used as the special alloy has been described. For example, a Ge—Te—Sb—S alloy, a Te—Ge—Sn—Au alloy, and a Ge—Te— alloy are used. Sn system, Sb-Se system, Sb-Se-Te system, Sn-Se-Te system, Ga-Se-Te system, Ga-Se-Te-Ge system, In-Se system, In-Se-Te system, An Ag—In—Sb—Te system, a Ge—Sb—Te type, or the like may be used.

  In the above embodiment, the case where user data is represented by 8 types (0 to 7) of multi-value data has been described. However, the present invention is not limited to this, and multi-value data other than 8 types is used. It may be expressed. That is, it does not have to be 8-valued.

  In the above embodiment, the program according to the present invention is recorded in the flash memory 39, but is recorded in another recording medium (CD, magneto-optical disk, DVD, memory card, USB memory, flexible disk, etc.). May be. In this case, the program according to the present invention is loaded into the flash memory 39 via the playback device (or dedicated interface) corresponding to each recording medium. Further, the program according to the present invention may be transferred to the flash memory 39 via a network (LAN, intranet, Internet, etc.). In short, it is sufficient that the program according to the present invention is stored in the flash memory 39.

  In the above embodiment, the case where the optical disk is an information recording medium corresponding to light having a wavelength of about 405 nm has been described. However, the present invention is not limited to this, and may be, for example, a CD or a DVD. .

  Moreover, although the said embodiment demonstrated the case where an optical disk was a phase change disk, it may be what is called a write-once disk not only in this.

  In the above embodiment, the case where the optical pickup device includes one semiconductor laser has been described. However, the present invention is not limited thereto, and for example, a plurality of semiconductor lasers that emit light beams having different wavelengths may be included. In this case, for example, at least one of a semiconductor laser that emits a light beam with a wavelength of about 405 nm, a semiconductor laser that emits a light beam with a wavelength of about 660 nm, and a semiconductor laser that emits a light beam with a wavelength of about 780 nm may be included. . That is, the optical disk apparatus may be an optical disk apparatus that supports a plurality of types of optical disks that conform to different standards. At this time, the multi-level recording method may be used for at least one of the plurality of types of optical discs.

  As described above, the recording condition determination method of the present invention is suitable for determining an appropriate recording condition when recording information multi-valued in three or more values on an optical disc. Further, the recording method and the optical disc apparatus of the present invention are suitable for recording information multi-valued to three or more values on an optical disc with high recording quality. The program and the storage medium of the present invention are suitable for causing an optical disc apparatus to record information multi-valued in three or more values on an optical disc with high recording quality.

1 is a block diagram showing a configuration of an optical disc device according to an embodiment of the present invention. It is a figure for demonstrating the structure of the optical pick-up apparatus in FIG. It is a figure for demonstrating multi-value information. It is a figure for demonstrating the reflected light intensity when reproducing | regenerating the information recorded by the multi-value recording system. It is a figure for demonstrating the target dynamic range. It is a figure for demonstrating the recording strategy in a multi-value recording system. It is a flowchart for demonstrating a recording process. FIG. 8A is a diagram for explaining the signal level of the target reproduction signal, and FIG. 8B is a diagram for explaining the signal level of the actually obtained reproduction signal. FIG. 8 is a flowchart for explaining an optimum recording power acquisition process in FIG. 7. FIG. FIG. 10 is a diagram for explaining a reproduction signal in the optimum recording power acquisition process of FIG. 9. FIG. 10 is a diagram for explaining normalization in the optimum recording power acquisition process of FIG. 9. FIG. 10 is a diagram for explaining a relationship between Id and m in the optimum recording power acquisition process of FIG. 9. FIG. 10 is a diagram for explaining coefficients a, b, and c in the optimum recording power acquisition process of FIG. 9. FIG. 10 is a diagram for explaining a relationship between a coefficient a and Pt in the optimum recording power acquisition process of FIG. 9. FIG. 10 is a diagram for explaining a modulation degree Mod in the optimum recording power acquisition process of FIG. 9. FIG. 10 is a diagram for explaining γt in the optimum recording power acquisition process of FIG. 9. FIG. 8 is a flowchart for explaining an optimum recording pulse width acquisition process in FIG. 7. FIG. FIG. 18 is a diagram for explaining coefficients a and b in the optimum recording pulse width acquisition process of FIG. 17. It is a figure for demonstrating the tolerance | permissible_range of a of FIG. FIG. 18 is a diagram for explaining normalization in the optimum recording pulse width acquisition process of FIG. 17. FIG. 18 is a diagram (No. 1) for explaining coefficients a ′ and b ′ in the optimum recording pulse width acquisition process of FIG. 17; FIG. 18 is a diagram (No. 2) for explaining coefficients a ′ and b ′ in the optimum recording pulse width acquisition process of FIG. 17; FIG. 18 is a diagram for explaining a relationship between a coefficient a ′ and Wt in the optimum recording pulse width acquisition process of FIG. 17. It is a figure for demonstrating the deformation | transformation of the recording mark by heat shortage. It is a figure for demonstrating the case where the coefficient a becomes out of an allowable range when m = 1. It is a figure for demonstrating Id in FIG. It is FIG. (1) for demonstrating coefficient a ', b' in FIG. FIG. 26 is a second diagram for explaining the coefficients a ′ and b ′ in FIG. 25. It is a figure for demonstrating the relationship between coefficient a 'and Wt in FIG. It is a figure for demonstrating the deformation | transformation of the recording mark by heat amount excess. FIG. 8 is a diagram (No. 1) for describing a modification of the optimum recording pulse width acquisition process in FIG. 7; FIG. 8 is a diagram (No. 2) for describing a modification of the optimum recording pulse width acquisition processing in FIG. 7; FIG. 8 is a flowchart for explaining a modified example of an optimum recording pulse width acquisition process in FIG. 7. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 15 ... Optical disk, 20 ... Optical disk apparatus, 23 ... Optical pick-up apparatus, 24 ... Laser control circuit (part of processing apparatus), 25 ... Encoder (part of processing apparatus), 39 ... Flash memory (recording medium, memory), 40: CPU (control device, control computer).

Claims (27)

An optical pickup device is used to irradiate a recording surface of an optical disc with a pulsed laser beam defined by a recording power and a recording pulse width and including a recording pulse for heating the recording surface. A recording condition determination method for determining a condition for recording information represented by three or more different M-value multivalued data,
Among the M types of multi-value data, test data including at least one data string in which multi-value data on which recording marks are formed on the recording surface is continuous is stored in a test writing area provided on the recording surface. A first step of trial writing while changing the recording pulse width stepwise;
Reproduce the area where the test data is written by trial, and for each recording pulse width, obtain a straight line connecting a plurality of reproduction signals corresponding to the same continuous multi-value data in the data string, and set the slope of the straight line. And a second step of determining an optimum recording pulse width based on the recording step. The test data includes a first data string in which first multi-value data in which a recording mark is formed on the recording surface and a record mark different from the first multi-value data is formed. A second data string in which two multi-value data are continuous,
In the second step, for each recording pulse width, a first straight line connecting a reproduction signal corresponding to each first multilevel data in the first data string, and each in the second data string An optimum recording pulse width for obtaining second straight lines connecting reproduction signals corresponding to the second multi-value data and recording the first multi-value data based on the slope of the first straight line. 2. The recording condition determination according to claim 1, further comprising: determining an optimum recording pulse width when recording the second multilevel data based on an inclination of the second straight line. Method. In the first multi-value data, the signal level of the reproduction signal corresponding to the first multi-value data is intermediate between the signal levels of M types of reproduction signals corresponding to the M types of multi-value data. Greater than or equal to
3. The recording condition determination method according to claim 2, wherein the second multi-value data has a signal level of a reproduction signal corresponding to the second multi-value data less than the intermediate value.   In the second step, a linear expression indicating the relationship between the inclination and the recording pulse width is obtained by an approximate calculation, and a recording pulse width corresponding to the inclination of 0 is obtained using the linear expression, and the recording pulse 4. The recording condition determining method according to claim 1, wherein the width is determined as an optimum recording pulse width. The M types of multi-value data include specific multi-value data in which no recording mark is formed,
The test data further includes a specific data string in which the specific multi-value data is continuous,
In the second step, the slope of a straight line connecting a plurality of reproduction signals corresponding to the same continuous multi-value data on which the recording mark is formed is the specific continuous multi-value data in the specific data string. 4. The recording condition according to claim 1, wherein the recording pulse width when the slope of a straight line connecting a plurality of reproduction signals corresponding to data coincides with the optimum recording pulse width. Decision method.   The recording condition determination method according to any one of claims 1 to 5, wherein the data string includes at least five identical multi-value data continuous. Prior to the first step, the method further includes a third step of obtaining an optimum recording power,
The recording condition determination according to any one of claims 1 to 6, wherein, in the first step, the test data is test-written with the optimum recording power acquired in the third step. Method. Prior to the first step, the same multi-value data includes M data strings each having the same multi-value data for the M types of multi-value data at the optimum recording power acquired in the third step. A fourth step of test writing test data in the test writing area;
The area written by trial in the fourth step is reproduced, and a straight line connecting a plurality of reproduction signals corresponding to the same continuous multi-value data is obtained for each data string, and the inclination of the straight line is preset. A fifth step of acquiring multi-value data that falls outside the permissible range, and
8. The recording condition determination according to claim 7, wherein, in the first step, test data including a data string in which multi-value data out of the allowable range is continuous is written in the test writing area. Method.   7. The test process according to claim 1, wherein, in the first step, the test data is test-written in the test-writing area with a recommended value of recording power pre-recorded on the optical disc. The recording condition determination method described.   The recording condition determination method according to claim 1, wherein the optical disk is an optical disk capable of rewriting recorded contents. An optical pickup device is used to irradiate a recording surface of an optical disc with a pulsed laser beam defined by a recording power and a recording pulse width and including a recording pulse for heating the recording surface. A recording method for recording information expressed by three or more different kinds of multi-valued data,
A recording method comprising a step of irradiating a pulsed laser beam including a recording pulse having a recording pulse width determined by the recording condition determining method according to claim 1 to record the information on an optical disc. . The recording surface of the optical disc is irradiated with a pulsed laser beam that is defined by the recording power and the recording pulse width and includes a recording pulse for heating the recording surface, and the signal levels of the corresponding reproduction signals differ from each other by 3 or more. A program used for an optical disc apparatus capable of recording information represented by M types of multi-value data,
Among the M types of multi-value data, test data including at least one data string in which multi-value data on which recording marks are formed on the recording surface is continuous is stored in a test writing area provided on the recording surface. First test writing while changing the recording pulse width stepwise;
Reproduce the area where the test data is written by trial, and for each recording pulse width, obtain a straight line connecting a plurality of reproduction signals corresponding to the same continuous multi-value data in the data string, and set the slope of the straight line. A program for causing a computer for controlling the optical disc apparatus to execute a second procedure for determining an optimum recording pulse width based on the second procedure; The test data includes a first data string in which first multi-value data in which a recording mark is formed on the recording surface and a record mark different from the first multi-value data is formed. A second data string in which two multi-value data are continuous,
As the second procedure, a region in which the test data is written on a trial basis is reproduced, and a reproduction signal corresponding to each first multi-valued data in the first data string is connected for each recording pulse width. A first straight line and a second straight line connecting the reproduction signals corresponding to each second multi-valued data in the second data string, respectively, and obtaining the first multiple based on the slope of the first straight line. Procedure for determining the optimum recording pulse width when recording the digitized data and determining the optimum recording pulse width when recording the second multi-valued data based on the slope of the second straight line The program according to claim 12, wherein the program is executed by the control computer. In the first multi-value data, the signal level of the reproduction signal corresponding to the first multi-value data is intermediate between the signal levels of M types of reproduction signals corresponding to the M types of multi-value data. Greater than or equal to
14. The program according to claim 13, wherein the second multilevel data has a signal level of a reproduction signal corresponding to the second multilevel data less than the intermediate value.   As the second procedure, a linear expression indicating the relationship between the inclination and the recording pulse width is obtained by an approximate calculation, and a recording pulse width corresponding to the inclination of 0 is obtained using the linear expression, and the recording pulse is obtained. The program according to any one of claims 12 to 14, wherein the control computer is caused to execute a procedure for determining a width as an optimum recording pulse width. The M types of multi-value data include specific multi-value data in which no recording mark is formed,
The test data further includes a specific data string in which the specific multi-value data is continuous,
As the second procedure, the slope of a straight line connecting a plurality of reproduction signals corresponding to the same continuous multi-value data on which the recording mark is formed is the specific continuous multi-value data in the specific data string. 15. The control computer is caused to execute a procedure for determining a recording pulse width as an optimum recording pulse width when it coincides with a slope of a straight line connecting a plurality of reproduction signals corresponding to data. The program as described in any one of. Prior to causing the control computer to execute a third procedure for obtaining an optimum recording power prior to the first procedure,
17. The control computer according to claim 12, wherein, as the first procedure, the control computer is caused to execute a test writing procedure of the test data with the optimum recording power acquired in the third procedure. The program as described in any one. Prior to the first procedure, the same multi-value data includes M data strings in which the same multi-value data is continuous for the M types of multi-value data with the optimum recording power acquired in the third procedure. A fourth procedure for test writing test data in the test writing area;
The region written by trial in the fourth procedure is reproduced, and straight lines connecting a plurality of reproduction signals corresponding to the same continuous multi-valued data are obtained for each data string, and the inclination of the straight line is preset. A fifth procedure for acquiring multi-value data that falls outside the allowable range, and causing the control computer to further execute;
As the first procedure, the control computer is caused to execute a procedure of trial writing test data including a data string in which multi-value data out of the allowable range is continuous in the trial writing area. The program according to claim 17.   13. The control computer is configured to cause the control computer to execute a test writing of the test data in the test writing area with a recommended value of the recording power recorded on the optical disc as the first procedure. The program as described in any one of -16.   A computer-readable recording medium on which the program according to any one of claims 12 to 19 is recorded. Three or more kinds of M or more of which the signal levels of the corresponding reproduction signals are different from each other by irradiating the recording surface of the optical disc with a pulsed laser beam defined by recording power and recording pulse width and including a recording pulse for heating the recording surface. An optical disc apparatus capable of recording information expressed by multi-value data of
A memory in which the program according to any one of claims 12 to 19 is recorded;
A control computer for determining an optimum recording pulse width in accordance with the program recorded in the memory;
An optical pickup device for emitting the laser beam;
An optical disk apparatus comprising: a processing device that irradiates the recording surface with a pulsed laser beam including a recording pulse having the determined recording pulse width via the optical pickup device and records the information. Three or more kinds of M or more of which the signal levels of the corresponding reproduction signals are different from each other by irradiating the recording surface of the optical disc with a pulsed laser beam defined by recording power and recording pulse width and including a recording pulse for heating the recording surface. An optical disc apparatus capable of recording information expressed by multi-value data of
An optical pickup device for emitting the laser beam;
Among the M types of multi-value data, test data including a data string in which at least one multi-value data on which a recording mark is formed is continuous is recorded in the test pulse area provided on the recording surface in the recording pulse width. The test writing area is reproduced, and a plurality of reproduction signals corresponding to the same continuous multi-value data in the data string obtained for each recording pulse width are connected. A control device for determining the optimum recording pulse width based on the slope of the straight line;
An optical disk apparatus comprising: a processing device that irradiates the recording surface with a pulsed laser beam including a recording pulse having the determined recording pulse width via the optical pickup device and records the information. The test data is different from the first multi-valued data and the first data sequence in which the first multi-valued data in which the recording mark is formed is continuous among the M types of multi-valued data. A second data string in which second multi-value data on which recording marks are formed is continuous,
The control device determines an optimum recording pulse width when recording the first multi-value data based on an inclination of a reproduction signal corresponding to the first data sequence, and also determines the second data sequence. 23. The optical disc apparatus according to claim 22, wherein an optimum recording pulse width when recording the second multi-value data is determined based on a slope of a reproduction signal corresponding to the reproduction signal. In the first multi-value data, the signal level of the reproduction signal corresponding to the first multi-value data is intermediate between the signal levels of M types of reproduction signals corresponding to the M types of multi-value data. Greater than or equal to
The optical disc apparatus according to claim 23, wherein the second multi-value data has a signal level of a reproduction signal corresponding to the second multi-value data less than the intermediate value.   The control device obtains a linear expression indicating the relationship between the inclination and the recording pulse width by an approximate calculation, obtains a recording pulse width corresponding to the inclination of 0 using the linear expression, and calculates the recording pulse width. The optical disc apparatus according to any one of claims 22 to 24, wherein an optimum recording pulse width is determined. The M types of multi-value data include specific multi-value data in which no recording mark is formed,
The test data further includes a specific data string in which the specific multi-value data is continuous,
In the control device, an inclination of a straight line connecting a plurality of reproduction signals corresponding to the same continuous multi-value data on which the recording mark is formed is added to the continuous specific multi-value data in the specific data sequence. The optical disk apparatus according to any one of claims 22 to 24, wherein a recording pulse width when the inclination of a straight line connecting a plurality of corresponding reproduction signals coincides is determined as an optimum recording pulse width. The control device according to any one of claims 22 to 26, wherein the control device acquires an optimum recording power prior to trial writing of the test data, and trial-writes the test data with the optimum recording power. The optical disc device according to one item.

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