JP2006309828A - Information recording method and information recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate acquisition of address information in a recorded area in an information recording medium. <P>SOLUTION: When setting a parameter of recording strategy for forming a recording mark in an optical recording medium, firstly, test recording is carried out using the parameter of recording strategy defined for each optical recording medium. Then, on the basis of the reading result of the formed recording mark, the parameter is adjusted so that an asymmetry value is within a predetermined range. Next, on the basis of the reading result of the recording mark formed with the parameter of the recording strategy so that an asymmetry value is within a predetermined range, the parameter is adjusted again so that a modulation factor is within a predetermine range. By adjusting the modulation factor in such a manner, the recording mark can be formed with a suitable width on the optical recording medium. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an information recording method for recording information on an information recording medium and an information recording apparatus for recording information on the information recording medium, and more particularly to setting recording conditions for the information recording medium.

  In recent years, optical recording media have been put to practical use as a kind of high-density information recording media, and in order to record a large amount of data such as video, the recording / reproducing laser light has a shorter wavelength and the laser beam has a smaller beam spot diameter. Is being promoted. As such an optical recording medium, for example, a write-once DVD-R (Digital Versatile Disc Recordable) has already been put into practical use. A DVD-R has a light absorption layer and a light reflection layer on a substrate, and information is recorded and reproduced by irradiating the light absorption layer of the rotating DVD-R with a laser beam of 630 to 660 nm. Is called. When information is recorded on the DVD-R, a relatively high power laser beam is irradiated. Thus, at the portion irradiated with the laser light having a relatively high power, the light absorption layer is decomposed, exploded or melted, and this portion becomes a recording mark. On the other hand, since the light absorption layer does not change in the portion where the laser beam is not irradiated, this portion becomes a space without a recording mark. Further, when reproducing recorded information, irradiation with a laser beam having a relatively low power that does not decompose the light absorption layer is performed. Then, the optical information is read using the difference in reflectance between the recording mark and the space.

  In order to accurately record information on such an optical recording medium, it is required to control the writing position of the recording mark with high accuracy. Therefore, the DVD-R includes a pre-groove (guide groove) for guiding laser light and a land pre-pit (LPP) as address information for determining a recording position by the laser light. Is formed. Among these, the pre-groove is spirally formed on the disk at a short pitch (1 μm or less), and in the case of DVD-R, the groove where the recording mark is formed and the land where the recording mark is not formed. And have. In the pre-groove, the boundary between the land and the groove is a wobble groove that meanders at a constant period in the radial direction of the disk. On the other hand, the land pre-pit is composed of pits (recesses) arranged in a pre-groove land area according to a predetermined rule (see, for example, Patent Document 1).

  In an information recording apparatus for recording information on a DVD-R, the detected wobble is detected using the fact that the reflected light from the wobble groove has a constant frequency (140 kHz in the case of 1 × speed) with respect to the irradiated laser light. Based on the groove signal, a signal for controlling a spindle motor for rotating the disk, a gate signal for detecting a land pre-pit, and the like are generated. Also, in the information recording apparatus, address information for recording, other information necessary for recording, and data based on the timing at which reflected light from the land prepit is detected with respect to the irradiated laser light High-accuracy position information for recording positioning at the time of recording is acquired. Therefore, when information is recorded, by combining these two methods, the position information (address) of the land pre-pit can be detected without error by the wobble groove signal, and the recording mark can be written with high accuracy. The position can be set.

  Further, in this type of information recording apparatus, it is required to accurately form recording marks corresponding to information to be recorded on an optical recording medium such as a DVD-R. Therefore, in order to form a recording mark with high accuracy, instead of continuously irradiating a high-power laser beam at a constant intensity, for example, a laser beam that is irradiated with a pulse train once the power is reduced after irradiating a high-power laser beam. The method using the profile is widely used. Recently, in response to the increase in recording speed, the top pulse period in which the laser beam is irradiated with the first power, the laser beam with the second power that is weaker than the first power following the top pulse period. It has also been proposed to configure the profile of the laser light intensity so as to include an intermediate bias period for irradiation and a last pulse period for again irradiating the laser light with the first power following this intermediate bias period. In this method, when a short recording mark is formed, a single pulse profile is used. Such a laser light intensity profile is called a recording strategy, and both the former and the latter methods are more effective in reducing the heat accumulation of the light absorption layer than the method of continuously irradiating laser light at a constant intensity. There is an advantage that the shape is difficult to be uneven. Further, by adjusting the waveform and length of the pulse train, or the lengths of the first power and the second power, the top pulse period, the intermediate bias period, and the last pulse period, a recording mark having a preferable shape can be accurately obtained. It is also possible to form. Further, by making the recording strategy for forming the recording mark following the space different according to the length of the space, it is possible to form a more accurate recording mark.

  For such recording strategy parameters, recommended values are determined for each optical recording medium manufacturer and for each type of optical recording medium, and this data is stored in, for example, a memory provided in the information recording apparatus. . Then, when the optical recording medium is mounted on the information recording apparatus, the information recording apparatus acquires information on the mounted optical recording medium, and records the recording strategy parameters corresponding to the acquired optical recording medium from the memory. Reading and setting. In some cases, parameters of the recording strategy are recorded in advance on the optical recording medium itself (this information is included in the information acquired from the land pre-pits). The recording strategy parameters are read from the recording medium and set.

  However, since the actual characteristics of optical recording media differ slightly from one sheet to another, a situation in which sufficient recording quality cannot be obtained simply by setting the recording strategy parameters read from the memory or optical recording medium. Can occur. Therefore, in the DVD standard, a test recording area (PCA: Power Calibration Area) for calibrating the power of the laser beam, for example, is provided separately from the data area for recording data, and the test is performed before actual data recording. Recording can be performed (see, for example, Patent Document 2).

JP 2003-346337 A (page 4, FIG. 1) JP 2004-55115 A (pages 11-12, FIG. 5)

  By the way, in the DVD-R described above, it is possible to perform “additional recording” in which data is recorded in a partial area of the data area and another data is recorded in another area at a later date. When performing additional recording, the DVD-R is irradiated with laser light, and the land pre-pits formed on the wobbled groove and land are read to confirm the address of the area where the data has already been recorded and the data is recorded. An operation such as searching for an address in an area that has not been performed is required.

  However, when data is recorded on a DVD-R at a high speed, for example, 16 times the standard speed, and then data is added, the phenomenon that the land pre-pits are difficult to read in the recorded area where the data has already been recorded occurs. Occurred. Specifically, as a result of difficulty in reading the land pre-pits, the value of BLERa (BLock Error Rate after), which is an address error rate after recording, has increased. When the value of BLERa is increased in this way, it becomes difficult to acquire position information in the data area of the DVD-R. Therefore, when recording other data, it is possible to search for the recording start position of other data. It will be difficult.

Here, Patent Document 1 describes that when a recording mark is formed in a portion of a groove adjacent to a land pre-pit, the power or pulse width of the laser beam is made different (for example, lowered) from normal. Has been. However, simply increasing or decreasing the power and pulse width of the laser beam to form the recording mark will cause the shape of the recording mark formed in the area adjacent to the land prepit to become unstable, and errors when reading the recording mark May increase.
Further, in Patent Document 2, a test recording is performed on the PCA using a predetermined recording strategy, and recording is performed so that the asymmetry value falls within a target range based on a result of reading the recording mark recorded by the test recording. It is described to adjust the parameters of the strategy. However, simply adjusting the parameters so that the asymmetry value is within the target range does not improve the BLERa value, and it still remains difficult to acquire position information in the recorded area.

  The present invention has been made to solve such a technical problem, and an object of the present invention is to facilitate acquisition of address information in a recorded area of an information recording medium.

  As a result of intensive studies by the inventor on the above-mentioned problems, even if the recording strategy parameters are the same, if the recording speed on the optical recording medium is increased, the longitudinal direction of the formed recording marks It has been found that the length (width) in the direction perpendicular to the width increases. When the width of the recording mark increases in this way, the recording mark protrudes from the groove and is also formed in a wobble groove or land (including land prepits provided on the land). For this reason, it has been found that it is difficult to read the land prepits and wobbled grooves in which the address information is recorded in the data area after recording, and the BLERa characteristics are deteriorated. The width of the recording mark changes in accordance with the modulation degree of the laser beam irradiated to form the recording mark, and becomes narrow when the modulation degree is low, and widens when the modulation degree is high. Therefore, the present inventor has found that such a decrease in BLERa can be suppressed by appropriately adjusting the degree of modulation of the laser light when forming the recording mark, and has come up with the present invention.

  That is, the information recording method of the present invention includes a first step of forming a recording mark on the information recording medium by irradiating the information recording medium with a light pulse created based on a predetermined parameter, and the information recording medium. A second step of obtaining asymmetry based on the reading result of the formed recording mark, and a third step of adjusting a predetermined parameter for forming an optical pulse when the asymmetry is not within a predetermined range. And a fourth step for obtaining the modulation degree based on the reading result of the recording mark formed on the information recording medium in which the asymmetry is within a predetermined range, and when the modulation degree is not within the predetermined range. And a fifth step of adjusting predetermined parameters for forming the light pulse.

  Here, in the first step, a recording mark can be formed in a test recording area provided on the outer periphery of the rotating information recording medium. Further, after the fifth step, error information relating to the address of the part where the recording mark is formed is acquired based on the reading result of the recording mark formed on the information recording medium and having a modulation degree within a predetermined range. A sixth step may be further included.

  Further, in the fifth step, when the modulation degree exceeds the upper limit of the predetermined range, the optical pulse output period is lengthened as one of the predetermined parameters, and the modulation degree exceeds the lower limit of the predetermined range. In this case, the output period of the light pulse can be shortened. In this case, the adjustment amount of the optical pulse output period is 1.6 times that of the shortest recording mark and the shortest recording mark, where ΔWt is the adjustment amount for a recording mark having a length of 1.6 times or more of the shortest recording mark. The adjustment amount for a recording mark having a length less than that can be set to 1/6 or less of ΔWt.

  Furthermore, in the fifth step, when the modulation degree exceeds the upper limit of the predetermined range, the generation timing of the optical pulse is advanced as one of the predetermined parameters, and the modulation degree exceeds the lower limit of the predetermined range. In this case, the generation timing of the light pulse can be delayed. In this case, the adjustment amount of the optical pulse generation timing is 1.6 times that of the shortest recording mark and the shortest recording mark, where ΔWt is the adjustment amount for a recording mark having a length 1.6 times or more that of the shortest recording mark. The adjustment amount for a recording mark having a length less than that can be set to ½ or less of ΔWt.

  In the first step, when forming the shortest recording mark and a recording mark having a length less than 1.6 times the shortest recording mark, a single pulse having the first power is irradiated as an optical pulse, and the shortest recording mark is irradiated. When forming a recording mark having a length 1.6 times longer than the recording mark, a top pulse having a first power, an intermediate bias having a second power weaker than the first power following the top pulse, The pulse group including the last pulse having the first power following the intermediate bias can be irradiated. Here, in the fifth step, when the modulation degree exceeds the upper limit of the predetermined range, the value obtained by dividing the first power by the second power is increased as one of the predetermined parameters, and the modulation degree is increased. Can exceed the lower limit of the predetermined range, the value obtained by dividing the first power by the second power can be reduced.

  Further, taking the category of the apparatus, the present invention is an information recording apparatus for forming a recording mark according to a recording signal by irradiating the information recording medium with light, and an optical head for irradiating the information recording medium with light. Formed on the information recording medium by the optical head, and a recording control unit that drives the optical head to generate a recording pulse signal based on the recording signal and to irradiate the information recording medium with the optical pulse based on the recording pulse signal And a parameter adjusting unit that adjusts parameters for generating the recording pulse signal so that the modulation degree obtained based on the read result of the recording mark falls within a predetermined range.

  Here, the parameter adjusting unit is a parameter for generating the recording pulse signal so that the asymmetry obtained based on the reading result of the recording mark formed on the information recording medium by the optical head is within a predetermined range. After adjusting the parameter, the parameter can be adjusted so that the modulation degree falls within a predetermined range. The parameter adjustment unit can adjust the length of the recording pulse, the generation and / or end timing of the recording pulse, and the intensity of the recording pulse as parameters for generating the recording pulse signal.

  Further, from another point of view, the present invention relates to a groove for forming a recording mark, a land formed between the grooves, a wobble groove provided at the boundary between the groove and the land and meandering at a constant cycle. An information recording apparatus for irradiating an information recording medium with light to form a recording mark corresponding to the recording signal, and generating an optical head for irradiating the information recording medium with light and a recording pulse signal based on the recording signal The recording control unit that drives the optical head to irradiate the information recording medium with an optical pulse based on the recording pulse signal, and the recording marks formed on the groove of the information recording medium by the optical head are formed on the wobble groove and land. A parameter adjusting unit for adjusting a parameter for generating a recording pulse signal is included so as not to protrude.

  Here, the parameter adjusting unit sets parameters for generating the recording pulse signal so that the length in the direction orthogonal to the longitudinal direction of the recording mark formed on the information recording medium by the optical head is within a predetermined range. Can be adjusted. And a drive control unit for controlling the position of the optical head and / or the rotation speed of the information recording medium based on address information obtained by reading a pit or wobble groove provided on a land of the information recording medium. Can do.

  According to the present invention, for example, the parameters for forming the optical pulse are set so that the degree of modulation is within a predetermined range, so that it is easy to obtain address information in the recorded area of the information recording medium. can do.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram (cross-sectional view) for explaining an optical recording medium 10 (DVD-R in this example) as an information recording medium on which information is recorded by an information recording method and an information recording apparatus to which this embodiment is applied. ).
The optical recording medium 10 includes a substrate 11 made of a light transmissive material such as polycarbonate, and a light absorbing layer 12 containing an organic dye and laminated on the substrate 11. The optical recording medium 10 includes a light reflection layer 13 and a protective layer 14 stacked on the light absorption layer 12. Here, irregularities are formed on the substrate 11, and the light absorption layer 12, the light reflection layer 13, and the protective layer 14 are also formed according to the irregularities. Information is recorded / reproduced on / from the optical recording medium 10 by a laser beam 16 irradiated from the substrate 11 side.

  A land L having a predetermined height and a groove G formed between the lands L are formed on the surface of the substrate 11. The light absorbing layer 12 and the light reflecting layer 13 are also laminated corresponding to the shape of the land L and the groove G. The groove G is continuously formed spirally from a predetermined position on the inner peripheral side of the optical recording medium 10 to a predetermined position on the outer peripheral side. The land L and the groove G are collectively referred to as a pregroove 15.

  Various materials can be used for the substrate 11 as long as it is a light-transmitting material at the wavelengths of recording light and reproducing light. For example, polycarbonate resins, vinyl chloride resins, acrylic resins such as polymethyl methacrylate, polystyrene resins, epoxy resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, polyimide resins, amorphous Examples thereof include polymer materials such as polyolefin; inorganic materials such as glass. Among these, polycarbonate resin is preferable.

The light absorption layer 12 is formed on the substrate 11 directly or via another layer. The thickness of the light absorption layer 12 is not particularly limited, but is usually 40 nm to 120 nm as measured from the bottom of the pregroove 15. Examples of the method for forming the light absorption layer 12 include commonly used thin film forming methods such as vacuum deposition, sputtering, doctor blade, cast, spinner, and immersion.
The organic dye forming the light absorbing layer 12 is not particularly limited as long as it is an organic dye usually used in the field of optical disks. For example, macrocyclic azaannulene dyes such as phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes; polymethine dyes such as cyanine dyes, merocyanine dyes, squarylium dyes; And dyes containing metal and metal-containing indoaniline dyes.

  The light reflecting layer 13 is formed on the light absorbing layer 12, and the thickness of the light reflecting layer 13 is usually 80 nm to 300 nm. As a material for forming the light reflecting layer 13, for example, metals of Au, Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta, and Pd can be used alone or as an alloy. Examples of the method for forming the light reflecting layer 13 include sputtering, ion plating, chemical vapor deposition, and vacuum vapor deposition.

The material of the protective layer 14 is not particularly limited as long as it protects the light reflecting layer 13. For example, examples of the organic substance include an ultraviolet curable resin. The inorganic _{substances, SiO 2, SiN 4, MgF} 2, SnO 2 and the like. As the ultraviolet curable resin, for example, acrylate resins such as urethane acrylate, epoxy acrylate, and polyester acrylate can be used.
As a method for forming the protective layer 14, similarly to the light absorption layer 12, a coating method such as a spin coating method or a casting method, a sputtering method, a chemical vapor deposition method, or the like is used. Of these, spin coating is preferred. The film thickness of the protective layer 14 is usually 3 μm to 6 μm.
In addition to the substrate 11, the light absorption layer 12, the light reflection layer 13, and the protective layer 14, other layers can be provided on the optical recording medium 10 to which this exemplary embodiment is applied, if necessary.

  2A and 2B are diagrams for explaining the land L and the groove G provided in the optical recording medium 10, FIG. 2A is a view of the optical recording medium 10 viewed from the upper side, and FIG. It is IIB-IIB sectional drawing of Fig.2 (a). In the present embodiment, the lands L and the grooves G are alternately formed along a direction (circumferential direction) orthogonal to the radial direction of the optical recording medium 10. In the optical recording medium 10 in the present embodiment, a recording mark to be described later is formed on the groove G. Here, at the boundary between each land L and each groove G, a wobble groove WG meandering at a constant period (25 μm in the case of DVD-R) in the radial direction of the disk is formed. Further, land prepits LPP are formed on the land L according to a predetermined rule. The lands L, grooves G, and land prepits LPP are already formed when the optical recording medium 10 is manufactured.

  FIG. 3 shows the structure of the recording area R of the optical recording medium 10. The recording area R has a recording information management area R-Info provided on the innermost disk side of the optical recording medium 10. The recording information management area R-Info is provided outside the first power calibration area PCA1 and the first power calibration area PCA1 for calibrating the laser power when recording data, and is used for recording management information. It has a recording management area RMA which is a storage area. The recording area R has a lead-in area Rin provided outside the recording information management area R-Info and a user data area DA provided outside the lead-in area Rin. Further, the recording area R is provided outside the user data area DA, and is provided outside the second power calibration area PCA2 and the second power calibration area PCA2 for calibrating the laser power during data recording. A lead-out region Rout is provided.

  In this optical recording medium 10, unlike a conventional optical recording medium (for example, DVD-R up to 4 × speed), a second power calibration area PCA2 as a test recording area is provided outside (outer peripheral part) of the recording area R. Is provided. This is because when data is recorded by the CLV (Constant Linear Velocity) method, it is difficult to perform high-speed recording on the inner circumference side of the disk (in this case, the spindle motor 40 described later must be rotated at a very high speed). This is usually because high-speed recording is performed on the outer peripheral side of the disc.

  FIG. 4 is a diagram for explaining an information recording / reproducing apparatus (information recording apparatus) 20 that records data on the above-described optical recording medium 10 and reproduces data recorded on the optical recording medium 10. The information recording / reproducing apparatus 20 includes an optical head 30, a spindle motor 40, a recording control unit 50, a reproduction control unit 60, a servo control unit 70, and a recording strategy adjustment unit 80.

  The optical head 30 includes a laser diode (not shown) and irradiates the optical recording medium 10 with a recording laser beam 16 and a reproducing laser beam 16. When the optical head 30 irradiates the recording laser beam 16, the optical head 30 irradiates the optical pulse in accordance with a recording pulse signal created by a recording control unit 50 described later. Further, the optical head 30 includes a photodetector (not shown), and photoelectrically converts the reflected light from the optical recording medium 10 and outputs it. The spindle motor 40 rotates the optical recording medium 10 at a predetermined speed. The recording control unit 50 controls the recording of information on the optical recording medium 10 based on the input recording signal. The reproduction control unit 60 controls reproduction of information already recorded on the optical recording medium 10 and outputs a reproduction signal. The servo control unit 70 controls various servos including a spindle servo that controls the rotation of the spindle motor 40 and a focusing servo and a tracking servo that are relative position controls of the optical head 30 with respect to the optical recording medium 10. Then, as will be described later, the recording strategy adjustment unit 80, based on the results obtained by reading the recording marks recorded on the optical recording medium 10 by the optical head 30 in accordance with a predetermined recording strategy, various parameters of the recording strategy. Adjust.

FIG. 5 is a block diagram illustrating in further detail the configuration of the recording control unit 50 and the reproduction control unit 60 in the information recording / reproducing apparatus 20 described above.
As shown in FIG. 5A, the recording control unit 50 includes an 8/16 modulation circuit 51, a recording waveform generation circuit 52, a laser drive circuit 53, and an EEPROM (Electrically Erasable and Programmable ROM) 54. Yes. The 8/16 modulation circuit 51 performs 8/16 modulation on a recording signal input from the outside and outputs it. The recording waveform generation circuit 52 generates a recording pulse signal in accordance with a predetermined recording strategy parameter based on the 8/16 modulated recording signal. The laser drive circuit 53 generates a drive signal for driving a laser diode provided in the optical head 30 in accordance with the generated recording pulse signal. The EEPROM 54 stores recording strategy parameters (predetermined parameters) set in advance for each manufacturer of the optical recording medium 10 and for each type of the optical recording medium 10. The recording waveform generation circuit 52 reads out the recording strategy parameter of the corresponding optical recording medium 10 from the EEPROM 54, and generates a recording pulse signal based on the parameter. Further, the recording waveform generation circuit 52 outputs the set recording strategy parameters to the recording strategy adjustment unit 80 described later. On the other hand, as will be described later, when the recording strategy adjustment unit 80 obtains a better recording strategy parameter, the recording strategy adjustment unit 80 inputs a new recording strategy parameter to the recording waveform generation circuit 52. Then, the recording waveform generation circuit 52 generates a recording pulse signal based on a new recording strategy parameter. Further, the 8/16 modulation circuit 51 receives the output timing of the 8/16 modulation signal (corresponding to the recording mark formation timing) from the reproduction control unit 60 described later.

  In the present embodiment, since the recording strategy parameters corresponding to the various optical recording media 10 are stored in the EEPROM 54, the recording strategy parameters can be rewritten (updated), for example, by upgrading the firmware. Therefore, when a better parameter is found for a certain optical recording medium 10 or when a new optical recording medium 10 is released, it is possible to cope with the firmware upgrade.

  As shown in FIG. 5B, the reproduction control unit 60 includes a preamplifier 61, a waveform equalization circuit 62, a binarization circuit 63, an 8/16 demodulation circuit 64, and an address information detection circuit 65. ing. The preamplifier 61 amplifies the read RF signal input from the optical head 30 to a predetermined level. The waveform equalization circuit 62 corrects and outputs the frequency characteristic of the amplified read RF signal. The binarization circuit 63 binarizes and outputs the read RF signal whose frequency characteristics have been corrected by the waveform equalization circuit 62. The 8/16 demodulating circuit 64 performs 8/16 demodulation on the binarized digital signal output from the binarizing circuit 63 and outputs it as a reproduction signal. The address information detection circuit 65 extracts a wobble signal corresponding to the wobble groove WG and an LPP signal corresponding to the land prepit LPP from the read RF signal amplified by the preamplifier 61, and based on these, addresses on the optical recording medium 10 are extracted. Detect information. The address information detection circuit 65 calculates the recording mark formation timing on the optical recording medium 10 based on the detected address information and outputs it to the 8/16 modulation circuit 51 of the recording control unit 50. Further, the reproduction control unit 60 outputs the read RF signal amplified to a predetermined level by the preamplifier 61 to the recording strategy adjustment unit 80 described later.

FIG. 6 is a block diagram illustrating in further detail the configuration of the servo control unit 70 and the recording strategy adjustment unit 80 in the information recording / reproducing apparatus 20 described above.
As shown in FIG. 6A, the servo control unit 70 as the drive control unit includes a focusing error detection circuit 71, a tracking error detection circuit 72, and a speed error detection circuit 73. The focusing error detection circuit 71 detects a focusing error of the read laser beam input from the optical head 30 based on the read RF signal input from the optical head 30. Then, the focusing error detection circuit 71 outputs a focusing servo signal to an actuator (not shown) that moves the objective lens (not shown) of the optical head 30 based on the detected focusing error. The tracking error detection circuit 72 detects a tracking error of the read laser beam input from the optical head 30 based on the read signal RF input from the optical head 30. The tracking error detection circuit 72 then outputs a tracking servo signal to a tracking motor (not shown) that moves the optical head 30 in the radial direction of the optical recording medium 10 based on the detected tracking error. The speed error detection circuit 73 detects a wobble signal obtained corresponding to the wobble groove WG (see FIG. 2) of the optical recording medium 10 from the read RF signal input from the optical head 30. Then, the speed error detection circuit 73 generates a spindle servo signal for maintaining the linear velocity constant based on the detected wobble signal and outputs it to the spindle motor 40.

  The recording strategy adjustment unit 80 includes a characteristic evaluation unit 81 and a parameter adjustment unit 82 as shown in FIG. The characteristic evaluation unit 81 performs evaluation on various characteristics of the recording mark (in particular, asymmetry and modulation degree in this embodiment) based on the result of reading the recording mark input from the reproduction control unit 60. However, the recording mark here refers to a recording mark recorded on the optical recording medium 10 by the optical head 30 according to a predetermined recording strategy. The parameter adjustment unit 82 adjusts the recording strategy parameter when the evaluation result of the recording mark by the characteristic evaluation unit 81 does not satisfy a predetermined condition, and the adjustment result is used as a recording waveform generation circuit of the recording control unit 50. 52 (see FIG. 5A).

  Next, the relationship (recording strategy) between the recording data for forming a recording mark of a predetermined length on the optical recording medium 10 and the waveform of the recording pulse signal (recording pulse waveform) will be described in detail. In the present embodiment, since information is recorded on the optical recording medium 10 using the 8/16 modulation method, the optical recording medium 10 includes 3T to 11T and 14T (T is a channel clock serving as a reference clock). Recording marks) can be formed. The optical recording medium 10 can also be formed with periods (space periods) without 3T to 11T and 14T recording marks.

  FIG. 7 shows recording marks having a length of 3T to 5T, 8T, and 14T among the 3T to 11T and 14T and recording pulse waveforms corresponding to the recording marks. As shown in FIG. 7, the recording pulse waveform for forming 3T and 4T length recording marks is a single pulse without an intermediate bias portion, unlike the case of 5T or more described later. On the other hand, a recording pulse waveform for forming a recording mark having a length of 5T or more is substantially concave, and is a top pulse for irradiating laser light with a first power, followed by a first power after the top pulse. An intermediate bias for irradiating the laser beam with a weaker second power, and a last pulse for irradiating the laser beam with the first power again after the intermediate bias are included. In the recording pulse waveform for forming a recording mark longer than 5T, the length of the intermediate bias period increases according to the length. The period of the top pulse and the period of the last pulse are basically substantially constant, although there are some changes.

  FIG. 8 explains the details of the recording pulse waveform described above. Here, the length of mT (m = 3 to 4, 3T in the example in the figure) and nT (n ≧ 5, 6T in the example in the figure). 2 illustrates a recording pulse waveform for forming a recording mark. The recording pulse waveform corresponding to mT is composed of a top pulse (single pulse) 90 because it is 4T or less as described above. Further, since the recording pulse waveform corresponding to nT is 5T or more as described above, it is composed of a top pulse 91, an intermediate bias 92, and a last pulse 93.

  In a recording pulse waveform for forming an mT recording mark corresponding to mT recording data, the top pulse 90 has a first write power P1, and its output period is the top pulse period mTtop. The generation timing of the top pulse period mTtop can be adjusted by the adjustment period mTdtop. In this example, the period of the read power P3 is provided immediately before the top pulse period mTtop.

  On the other hand, in the recording pulse waveform for forming the nT recording mark corresponding to the nT recording data, the top pulse 91 and the last pulse 93 have the first write power P1, and the intermediate bias 92 has the second bias. Write power P2. Here, the second write power 92 is set lower than the first write power P1 and higher than the read power P3. The output period of the top pulse 91 is a top pulse period nTtop, and the output period of the last pulse 93 is a last pulse period nTlp. Further, the output period of the top pulse period nTtop, the intermediate bias period, and the last pulse period nTlp is the pulse output period nTwt. Therefore, the intermediate bias period can be expressed by nTwt−nTtop−nTlp.

Here, in FIG. 9A, the information recording / reproducing apparatus 20 forms recording marks M (specifically, M1, M2, M3) on the groove G of the optical recording medium 10 using parameters of different recording strategies. An example is shown. FIG. 9B shows a radial push-pull signal (a wobble signal and a land pre-pit signal (LPP signal)) obtained when the recording mark M1 is read. Further, FIG. 9C shows a Radial Push-Pull signal obtained along with reading of the recording marks M2 and M3. This Radial Push-Pull signal is used in the address information detection circuit 65 (see FIG. 5B) provided in the reproduction control unit 60 of the information recording / reproducing apparatus 20.
Here, the wobble signal is a sinusoidal signal obtained by reading the wobble groove WG. The wobble signal is used for controlling the rotational speed of the spindle motor 40 based on, for example, the period (frequency). The wobble signal is used to generate a gate signal for detecting the land prepit LPP without error. On the other hand, the LPP signal is a pulse-like signal obtained by reading the land prepit LPP. The LPP signal is used to detect a position (address) on the optical recording medium 10. The LPP signal can also be used for phase correction of the channel clock T.

  Here, in the recording mark M1 shown on the left side of FIG. 9A, the length (width) in the direction orthogonal to the longitudinal direction of the recording mark M1 is too wide. For this reason, the recording mark M1 covers a part of the wobbled groove WG and the land L (land prepit LPP formed on the land L). Further, in the recording mark M2 shown in the center of FIG. 9A, the width of the recording mark M2 is appropriate, and the recording mark M2 covers the wobbled groove WG and the land L (land prepit LPP formed on the land L). Not. Further, the recording mark M3 shown on the right side of FIG. 9A does not cover a part of the wobbled groove WG or the land L (land prepit LPP formed on the land L) unlike the recording mark M1, The mark width is too narrow.

  As shown in FIG. 9 (b), the wobble signal obtained by reading the wide recording mark M1 has a smaller amplitude than the wobble signal obtained by reading the recording marks M2 and M3 described later. Or it is distorted. This is because when the recording mark M1 is formed so as to protrude beyond the wobbled groove WG, the intensity of reflected light from that portion is significantly reduced. If the amplitude of the wobble signal is reduced, the accuracy of the rotation of the spindle motor 40 and the generation of the gate signal for detecting the land prepit LPP will be reduced accordingly. Further, the peak value of the LPP signal obtained along with the reading of the wide recording mark M1 is smaller than the wobble signal obtained along with the reading of the recording marks M2 and M3 described later. The address information detection circuit 65 (see FIG. 5B) performs binarization based on whether or not the LPP signal exceeds the threshold slice level SL, and detects the presence or absence of the land prepit LPP. Therefore, when the level of the LPP signal is lowered, there is a case where the LPP signal cannot exceed the slice level SL. In this case, the address cannot be detected.

  On the other hand, as shown in FIG. 9C, the wobble signal obtained by reading the recording marks M2 and M3 has a larger amplitude than the wobble signal obtained by reading the recording mark M1. Accordingly, the accuracy of the rotation speed control of the spindle motor 40 (see FIG. 4) and the generation of the gate signal for detecting the land prepit LPP are improved. Further, the peak value of the LPP signal obtained along with the reading of the recording marks M2 and M3 is larger than that of the wobble signal obtained along with the reading of the recording mark M1. Therefore, it is possible to accurately detect the address. However, with the narrower recording mark M3, the detection accuracy of the wobble signal and the LPP signal is certainly increased, but it becomes difficult to read the recording mark M3 itself, and an error of the data signal is likely to occur. Therefore, in order to ensure both the detection accuracy of the wobble signal and the LPP signal and the reading accuracy of the data signal, it is important to form the recording mark M2 having an appropriate width on the optical recording medium 10.

Therefore, in the present embodiment, before the data is actually recorded on the optical recording medium 10 using the information recording / reproducing apparatus 20, various test recordings are performed so that the recording mark M having an appropriate width can be formed. ing. Specifically, while performing test recording, parameters in the recording strategy for forming the recording mark M are adjusted so that the asymmetry and the degree of modulation satisfy predetermined conditions.
Here, asymmetry is a deviation of the center level between the short recording mark / short space and the long recording mark / long space in the reproduction signal (read RF signal) when all the recording marks / spaces of 3T to 11T and 14T are recorded. It is a parameter indicating the degree. A high asymmetry value means that the deviation level of the center level is large.
On the other hand, the modulation degree is obtained by dividing the maximum amplitude of the reproduction signal (read RF signal) when the recorded recording mark M is reproduced by the maximum value of the reproduction signal (read RF signal). Take the range of ~ 1. The low degree of modulation means that the formed recording mark M is difficult to read, specifically, for example, the width M of the recording mark is narrow.

Now, the overall flow of processing in the test recording operation will be described with reference to the flowchart shown in FIG.
When the optical recording medium 10 is set in the information recording / reproducing apparatus 20, the optical head 30 reads the recording management area RMA of the recording information management area R-Info of the optical recording medium 10 and acquires the ID of the optical recording medium 10, that is, the medium. (Step 101). The acquired media ID is output from the playback control unit 60 to the recording control unit 50 via the recording strategy adjustment unit 80. Next, the recording control unit 50 reads the recording strategy setting information (parameter) corresponding to the acquired media ID from the EEPROM 54 and sets the read recording strategy setting information in the recording waveform generating circuit 52 ( Step 102). Based on the set recording strategy setting information, 3T to 14T recording marks (test recording marks) are created on the optical recording medium 10 using the optical head 30 (step 103). In creating the test recording mark, the optical head 30 has moved to a position facing the second power calibration area PCA2 of the optical recording medium 10, and the test recording mark is provided in the second power calibration area PCA2. The created groove G is created. In creating the test recording mark, the spindle motor 40 is servo-controlled so that the linear velocity at the recording position of the optical recording medium 10 is 16 times the standard velocity.

  Next, the optical head 30 reads a recording mark formed on the optical recording medium 10, and an asymmetry value is calculated in the characteristic evaluation unit 81 of the recording strategy adjustment unit 80 based on the reading result (step 104). Then, it is determined whether or not the obtained asymmetry value is within the range of the standard (specifically, whether or not it is within the range of -0.05 to 0.15) (step 105). Here, when the asymmetry value is not within the standard range, in the parameter adjustment unit 82 of the recording strategy adjustment unit 80, the pulse length of the laser light in the recording strategy setting information used in the recording waveform generation circuit 52, The laser beam irradiation timing, irradiation power, and the like are changed as appropriate (step 106) and output to the recording waveform generation circuit 52. Then, returning to step 103, recording marks are formed again with recording strategy setting information different from the previous time. It should be noted that a conventional procedure can be adopted as a method of changing the recording strategy parameter for adjusting the asymmetry value performed in step 106.

  On the other hand, if the asymmetry value is within the standard range in step 105, then the recording mark formed on the optical recording medium 10 is read, and the modulation degree is calculated in the characteristic evaluation unit 81 based on the read result. (Step 107). However, if the recording mark has already been read in step 104, the calculation can be performed using the data as it is. Then, it is determined whether or not the obtained modulation degree is within an allowable range (step 108). For example, in the DVD standard, the modulation degree is required to be 0.60 or more and no upper limit is provided, but in the present embodiment, a lower limit and an upper limit are provided in the allowable range of the modulation degree. Yes. In this example, the lower limit is set to 0.60, for example, and the upper limit is set to 0.80, for example. Here, when the degree of modulation is not within the allowable range, the parameter adjustment unit 82 uses the recording strategy setting information used in the recording waveform generation circuit 52, the pulse length of the laser beam, the irradiation timing of the laser beam, and the irradiation The power and the like are changed as appropriate (step 109) and output to the recording waveform generation circuit 52. The new recording strategy setting information is set in the recording waveform generation circuit 52. Based on the set information of the new recording strategy that has been set, 3T to 14T recording marks (test recording marks) are again created on the optical recording medium 10 using the optical head 30 (step 110). Note that the recording mark formation position on the optical recording medium 10 at this time is different from the previous recording mark. Then, the process returns to step 107 to continue the processing.

  On the other hand, if the modulation degree is within the allowable range in step 108, the recording mark formed on the optical recording medium 10 is read, and the characteristic evaluation unit 81 of the recording strategy adjustment unit 80 is read based on the reading result. In step 111, the asymmetry value is calculated. Then, it is determined whether or not the obtained asymmetry value is within the standard range (step 112). If the asymmetry value is not within the standard range, the process returns to step 106.

  On the other hand, if the asymmetry value is within the standard range in step 112, the reproduction signal (when reading the recording mark whose asymmetry value is within the standard range and the modulation degree is within the allowable range ( Based on the read RF signal), the characteristic evaluation unit 81 calculates a value of BLERa that is an address error rate after recording (step 113). That is, error information regarding the address is acquired. Then, it is determined whether or not the obtained value of BLERa is equal to or less than a predetermined value (for example, 1%) (step 114). Here, if the value of BLERa exceeds a predetermined value, the process returns to step 109 to continue the processing. On the other hand, if the value of BLERa is equal to or smaller than the predetermined value, this process, that is, the test recording process is terminated. In the information recording / reproducing apparatus 20, actual data is recorded on the optical recording medium 10 by the recording strategy set in such a process.

FIG. 11 shows the flow of processing performed in step 109 described above, that is, the recording strategy parameter adjustment process performed by the parameter adjustment unit 82 of the recording strategy adjustment unit 80 in order to keep the modulation degree within the allowable range. Will be described in detail with reference to FIG.
In the parameter adjustment of the recording strategy for keeping the modulation degree within the common range, first, nT, that is, the pulse output period nTwt of 5T to 14T is expanded (step 201). At this time, the pulse output period nTwt is gradually expanded, and the adjustment amount is ΔWt. If the value of ΔWt is too large, for example, a 5T recording mark is read as a 6T recording mark. Therefore, there is an upper limit to the magnitude of ΔWt that can be taken.

  Next, nT, that is, the top pulse period nTtop of 5T to 14T is narrowed (step 202). At this time, the top pulse period nTtop is gradually narrowed, and the adjustment amount is Δntop. If the value of Δntop is too large, the top pulse period nTtop becomes zero. For this reason, there is an upper limit to the size of Δntop that can be taken.

Next, the last pulse period nTlp of nT, that is, 5T to 14T is extended (step 203). At this time, the last pulse period nTlp is gradually widened, and the adjustment amount is Δnlp. Note that if the value of Δnlp becomes too large, the last pulse period nTlp becomes zero. For this reason, there is an upper limit to the size of Δnlp that can be taken.
Next, the top pulse period mTtop of mT, that is, 3T, 4T is expanded (step 204). At this time, the top pulse period mTtop is gradually widened, and the adjustment amount is Δmtop. In this example, the upper limit of Δmtop is set to 1/6 or less of the above ΔWt. The reason is that if Δmtop exceeds this level, for example, a 3T recording mark may be read as a 4T recording mark, or a 4T recording mark may be read as a 5T recording mark. . For this reason, there is an upper limit to the size of Δmtop that can be taken.

Next, mT, that is, the adjustment period mTdtop of 3T and 4T is advanced (step 205). That is, the top pulse generation timing of 3T and 4T is advanced. At this time, the top pulse generation timing is gradually advanced, and the adjustment amount is Δmdtop. In this example, the upper limit of Δmdtop is set to ½ or less of ΔWt. The reason is that if Δmdtop exceeds this level, the recording mark formation position is greatly displaced, and the space before and after the recording mark may be read as a wrong size space. For this reason, there is an upper limit to the size of Δmdtop that can be taken.
Finally, P1 / P2, which is the ratio between the first write power P1 and the second write power P2 in nT, that is, 5T to 14T, is increased (step 206). At this time, P1 / P2 is gradually increased. When the ratio of P1 / P2 is determined, a series of processing ends.

Now, taking a specific example, the adjustment of the modulation degree by the test recording described above and the improvement of BLERa which is the address error rate after recording accompanying this will be described. In this example, information is recorded on the optical recording medium 10 at a high speed (16 times the standard speed). Therefore, test recording on the optical recording medium 10 is performed in the second power calibration area PCA2 shown in FIG.
(Preparation of optical recording medium 10)
First, each layer structure of the optical recording medium 10 having the structure shown in FIG. 1 was adjusted as follows.
A tracking pregroove 15 was previously spirally formed on a polycarbonate resin substrate 11 having a thickness of 0.6 mm. The pregroove 15 has an innermost radius of 22 mm, an outermost radius of 58 mm, a track pitch of 0.74 μm, a depth of 165 nm, and a groove width of 320 nm.
Next, an azo dye / tetrafluoropropanol solution was applied to the surface of the substrate 11 on which the pregroove 15 was formed by a spin coating method to a thickness of 120 mm to form the light absorption layer 12. Subsequently, an Ag alloy was sputtered on the light absorption layer 12 to form a light reflection layer 13 having a thickness of 0.14 μm. Further, an ultraviolet curable resin is applied on the light reflecting layer 13 to a thickness of 5 μm by a spin coating method, and the ultraviolet curable resin is cured by irradiating with an ultraviolet ray having a predetermined light intensity, whereby the protective layer 14 is formed. A write-once type optical recording medium 10 having a light absorption layer 12 made of an azo dye was prepared.

(Test record)
Next, the optical recording medium 10 was set in the information recording / reproducing apparatus 20 shown in FIG. 2, and test recording was performed. Note that the target range of asymmetry in this test recording was 0 ± 1%, and the allowable range of modulation was 0.75 to 0.80. The optical recording medium 10 was rotated at a CLV with a linear velocity of 55.84 m / s corresponding to 16 times the standard speed of 3.49 m / s at a position of radius 58 mm of the optical recording medium 10. Further, the laser beam 16 having a wavelength of 659 nm is condensed by an objective lens having a numerical aperture of 0.60 provided in the optical head 30, and 1 channel clock (T) is set to 4.78 nsec. Created a mark.

  In creating 3T to 14T recording marks on the optical recording medium 10, first, a first recording strategy parameter (referred to as strategy A in the following description) determined corresponding to the optical recording medium 10 was used. In the strategy A, the first write power P1 was set to 49.5 mW, and the second write power P2 was set to 34.1 W (P1 / P2 = 1.45). The recording pattern was random. Table 1 shows each parameter in the strategy A.

  Information including the recording mark recorded on the optical recording medium 10 in this way was rotated at CLV with a linear velocity of 3.49 m / s and reproduced with a read power P3 of 0.8W. As a result, as shown in Table 2, in the strategy A, the jitter was as good as 7.41% and the asymmetry was 1%, but the modulation degree was as large as 0.83, which was obtained after recording from the land prepit LPP. BLERa, which is the address error rate, was as high as 5.4%.

  Next, in order to improve BLERa which is an address error rate after recording, the parameter adjusting unit 82 shown in FIG. 6B performs the processing shown in FIGS. 10 and 11 to obtain the pulse length, the irradiation timing, The irradiation power was adjusted. As a result, as shown in Table 1, the pulse output period nTwt corresponding to the pulse length of 5T to 14T was increased by 0.65T. In addition, the 3T top pulse period 3Ttop corresponding to the 3T pulse length is lengthened by 0.075T, and the 4T top pulse period 4Ttop corresponding to the 4T pulse length is lengthened by 0.025T. Further, the adjustment period 3Tdtop of the 3T top pulse generation timing is advanced by 0.200T, and the adjustment period 4Tdtop of the 4T top pulse generation timing is advanced by 0.250T. Then, P1 / P2 which is a ratio of the first write power P1 and the second write power P2 is increased to 1.75. Specifically, the first write power P1 was set to 47.3 mW, and the second write power P2 was set to 27.0 W. When the ratio between the first write power P1 and the second write power P2 is changed, it is preferable that the amount of decrease in the second write power P2 is larger than the amount of decrease in the first write power P1. . Based on the parameters of the second recording strategy thus changed (hereinafter referred to as strategy B), a recording mark was created on the optical recording medium 10 in the same manner as strategy A described above. Table 1 also shows each parameter in the strategy B.

  Information including the recording mark recorded on the optical recording medium 10 in this way was rotated at CLV with a linear velocity of 3.49 m / s, and read power P3 was reproduced at 0.8 W. As a result, as shown in Table 2, in the strategy B, the jitter is 7.52%, the asymmetry is -1%, the modulation degree is as small as 0.80, and the post-recording obtained from the land prepit LPP The BLERa, which is the address error rate, was reduced to 0.0%.

  As described above, in the present embodiment, by reducing the modulation degree to an appropriate size, the width of the formed recording mark shown in FIG. 9 is narrowed within an appropriate range, and the recording mark becomes a wobble groove WG or land L. It is thought that the protrusion to the land L (including the land prepit LPP formed on the land L) is suppressed. For this reason, it is considered that the land pre-pits LPP can be easily detected even after recording, and the value of BLERa that is the address error rate after recording is remarkably lowered.

  In the above-described example, the allowable range of the modulation degree is set to 0.75 to 0.80, but the present invention is not limited to this. For example, in the DVD standard, it is determined that the modulation degree is 0.60 or more. Therefore, the lower limit value can be appropriately selected from values of 0.60 or more. Further, the upper limit value can be appropriately selected according to various characteristics of the optical recording medium 10 and the information recording / reproducing apparatus 20.

As described above, in this embodiment, when setting the recording strategy parameter for forming the recording mark on the optical recording medium 10, the modulation degree is adjusted so as to be within the predetermined allowable range. did. Then, by adjusting the modulation degree, a recording mark can be formed on the optical recording medium 10 with an appropriate width. For this reason, for example, when the width of the recording mark is too wide, the formation of the recording mark in the land prepit LPP on the land L can be suppressed, and the value of the address error rate BLERa after recording can be reduced. . As a result, an address can be easily acquired even in a recorded area of the optical recording medium 10, and address search when additional recording is performed on the optical recording medium 10 is facilitated. On the other hand, for example, if the width of the recording mark is too narrow, it is difficult to read the formed recording mark and a situation in which a reading error occurs can be suppressed. Therefore, the recorded address signal (LPP signal) can be stably acquired even when there is a variation in the optical recording medium 10 or a variation in the information recording / reproducing apparatus 20.
Further, since the recording mark can be formed with an appropriate width by adjusting the modulation degree, it is possible to suppress the formed recording mark from being applied to the wobble groove WG, and the spindle motor 40 by the servo controller 70. Control, that is, the rotational speed control of the optical recording medium 10 can be accurately performed.

  In particular, in the present embodiment, first, the recording strategy parameter is adjusted so that the asymmetry is within the standard range, and then the recording strategy parameter is adjusted again so that the degree of modulation is within the predetermined allowable range. I made it. By obtaining the recording strategy parameters in this manner, it is possible to form a recording mark having a stable shape on the optical recording medium 10. Then, after obtaining the recording strategy parameters corresponding to the asymmetry and the modulation degree, the writing quality can be confirmed by further evaluating BLERa which is the address error rate after recording.

  In the present embodiment, the DVD-R has been described as an example of the optical recording medium 10, but the present invention is not limited to this. That is, in addition to the optical recording medium 10 in which the address information is formed as land prepits LPP on the land L as in the DVD-R, for example, the address information is stored in the wobble groove WG as in the known DVD + R. The present invention can be similarly applied to a method using an embedding so-called ADIP (Address In Pre-groove) method.

  In the present embodiment, since recording is performed on the optical recording medium 10 at 16 times the standard speed, test recording is performed in the second power calibration area PCA2. However, the present invention is not limited to this. is not. That is, the method described in the present embodiment is effective even when recording is performed on the optical recording medium 10 at a speed not more than 8 times the standard speed. In such a case, the inner peripheral portion of the optical recording medium 10 is used. The test recording is performed in the first power calibration area PCA1 provided in.

It is a figure for demonstrating the optical recording medium (DVD-R) on which information is recorded by the information recording method and information recording apparatus with which this Embodiment is applied. It is a figure for demonstrating the land and groove provided in an optical recording medium, (a) is the figure which looked at the optical recording medium from the upper side, (b) is IIB-IIB sectional drawing of (a). It is the figure which showed the structure of the recording area of an optical recording medium. It is a figure for demonstrating the information recording / reproducing apparatus which records data on an optical recording medium, and reproduces | regenerates the data recorded on the optical recording medium. (a) is a figure explaining the structure of a recording control part, (b) is a figure explaining the structure of a reproduction | regeneration control part, respectively. (a) is a figure explaining the structure of a servo control part, (b) is a figure explaining the structure of a recording strategy adjustment part, respectively. It is a figure which shows the relationship between the mark length which should be recorded, and the corresponding recording pulse waveform. It is a figure explaining the detail of the recording pulse waveform used when forming the recording mark of 5T-14T. (a) shows the relationship between the formed recording mark and the damage received by the groove and land prepit, (b) shows the wobble signal and LPP signal when the modulation degree is too high, and (c) shows the appropriate modulation degree. It is a figure which shows the wobble signal and LPP signal in the case where it is low and when it is too low, respectively. It is a flowchart which shows the flow of the process in test recording operation | movement. It is a flowchart which shows the parameter adjustment process of the recording strategy for keeping a modulation degree in a predetermined range in test recording operation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Optical recording medium (DVD-R), 11 ... Board | substrate, 12 ... Light absorption layer, 13 ... Light reflection layer, 14 ... Protective layer, 15 ... Pregroove, 16 ... Laser beam, 20 ... Information recording / reproducing apparatus, 30 DESCRIPTION OF SYMBOLS ... Optical head, 40 ... Spindle motor, 50 ... Recording control part, 51 ... 8/16 modulation circuit, 52 ... Recording waveform generation circuit, 53 ... Laser drive circuit, 54 ... EEPROM, 60 ... Reproduction control part, 61 ... Preamplifier, 62 ... Waveform equalization circuit, 63 ... Binarization circuit, 64 ... 8/16 demodulation circuit, 70 ... Servo controller, 71 ... Focusing error detection circuit, 72 ... Tracking error detection circuit, 73 ... Speed error detection circuit, 80 ... Recording strategy adjustment unit, 81 ... Characteristic evaluation unit, 82 ... Parameter adjustment unit

Claims (15)

A first step of irradiating an information recording medium with a light pulse created based on a predetermined parameter to form a recording mark on the information recording medium;
A second step of obtaining an asymmetry based on a reading result of the recording mark formed on the information recording medium;
A third step of adjusting the predetermined parameter for forming the light pulse when the asymmetry is not within a predetermined range;
A fourth step of obtaining a modulation degree based on a reading result of a recording mark formed on the information recording medium and in which the asymmetry is within the predetermined range;
And a fifth step of adjusting the predetermined parameter for forming the optical pulse when the degree of modulation is not within the predetermined range.   2. The information recording method according to claim 1, wherein, in the first step, the recording mark is formed in a test recording area provided in an outer peripheral portion of the rotating information recording medium.   After the fifth step, an error relating to the address of the part where the recording mark is formed based on the reading result of the recording mark formed on the information recording medium and having the modulation factor within the predetermined range The information recording method according to claim 1, further comprising a sixth step of acquiring information.   In the fifth step, when the modulation degree exceeds the upper limit of the predetermined range, the output period of the optical pulse is lengthened as one of the predetermined parameters, and the modulation degree is within the predetermined range. 2. The information recording method according to claim 1, wherein an output period of the optical pulse is shortened when the lower limit of the optical pulse is exceeded.   The adjustment amount of the output period of the optical pulse is less than 1.6 times the shortest recording mark and the shortest recording mark, where ΔWt is the adjustment amount for a recording mark having a length 1.6 times longer than the shortest recording mark. 5. The information recording method according to claim 4, wherein an adjustment amount for a recording mark having a length of is set to 1/6 or less of the ΔWt.   In the fifth step, when the modulation degree exceeds the upper limit of the predetermined range, the generation timing of the optical pulse is advanced as one of the predetermined parameters, and the modulation degree is within the predetermined range. 2. The information recording method according to claim 1, wherein the timing of generating the light pulse is delayed when the lower limit of the above is exceeded.   The adjustment amount of the generation timing of the light pulse is less than 1.6 times the shortest recording mark and the shortest recording mark, where ΔWt is the adjustment amount for a recording mark having a length 1.6 times or more that of the shortest recording mark. The information recording method according to claim 6, wherein an adjustment amount for a recording mark having a length of is less than or equal to ½ of ΔWt.   In the first step, when forming the shortest recording mark and a recording mark having a length less than 1.6 times the shortest recording mark, a single pulse having a first power is irradiated as the optical pulse, When forming a recording mark having a length 1.6 times longer than the shortest recording mark, a top pulse having the first power, a second power weaker than the first power following the top pulse The information recording method according to claim 1, wherein a pulse group including an intermediate bias having a first pulse and a last pulse having the first power following the intermediate bias is irradiated.   In the fifth step, when the modulation degree exceeds the upper limit of the predetermined range, a value obtained by dividing the first power by the second power is increased as one of the predetermined parameters. 9. The information recording method according to claim 8, wherein when the modulation degree exceeds a lower limit of the predetermined range, a value obtained by dividing the first power by the second power is reduced. An information recording apparatus for forming a recording mark according to a recording signal by irradiating an information recording medium with light,
An optical head for irradiating the information recording medium with light;
A recording control unit that generates a recording pulse signal based on the recording signal and drives the optical head to irradiate the information recording medium with an optical pulse based on the recording pulse signal;
A parameter adjustment unit for adjusting a parameter for generating the recording pulse signal so that a modulation degree obtained based on a reading result of a recording mark formed on the information recording medium by the optical head is within a predetermined range. An information recording device including:   The parameter adjusting unit is configured to generate the recording pulse signal so that an asymmetry obtained based on a reading result of a recording mark formed on the information recording medium by the optical head is within a predetermined range. The information recording apparatus according to claim 10, wherein after adjusting a parameter, the parameter is adjusted so that the degree of modulation falls within the predetermined range.   The parameter adjustment unit adjusts the length of the recording pulse, the generation and / or end timing of the recording pulse, and the intensity of the recording pulse as parameters for generating the recording pulse signal. Item 10. The information recording device according to Item 10. Light is irradiated to an information recording medium having a groove for forming a recording mark, a land formed between the grooves, and a wobble groove provided at a boundary between the groove and the land and meandering at a constant cycle. An information recording apparatus for forming the recording mark according to a recording signal,
An optical head for irradiating the information recording medium with light;
A recording control unit that generates a recording pulse signal based on the recording signal and drives the optical head to irradiate the information recording medium with an optical pulse based on the recording pulse signal;
A parameter adjusting unit that adjusts a parameter for generating the recording pulse signal so that the recording mark formed on the groove of the information recording medium by the optical head does not protrude from the wobble groove and the land. Including information recording device.   The parameter adjusting unit generates the recording pulse signal so that a length in a direction orthogonal to a longitudinal direction of a recording mark formed on the information recording medium by the optical head is within a predetermined range. 14. The information recording apparatus according to claim 13, wherein a parameter is adjusted.   A drive control unit for controlling the position of the optical head and / or the rotational speed of the information recording medium based on address information obtained by reading a pit or the wobble groove provided on the land of the information recording medium; 14. The information recording apparatus according to claim 13, further comprising:

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