JP2006277929A - Optical disk apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk and an optical disk apparatus capable of optimum recording and reproducing of information. <P>SOLUTION: The optical disk 1 has a lead-in area 4 in which information concerning characteristics of an optical head for use in recording or reproducing the information and an optimum condition of a light beam for recording the information on the optical disk or reproducing the information from the optical disk are recorded. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical disc and an optical disc apparatus capable of recording, erasing and reproducing information optimally in an information recording medium capable of recording, erasing or reproducing information using a laser beam.

  An optical disk as an information recording medium is represented by a read-only type represented by CD and DVD-ROM, a once-write type represented by CD-R and DVD-R, an external memory of a computer and a recording / playback video. There are rewritable types.

  In these, the red laser of the DVD is changed from the infrared laser of the CD disk device. In this case, reducing the diameter of the focused spot by shortening the laser wavelength means that, for example, when recording information, a different recording power may be used for each optical disc due to differences in the structure and composition of the recording film of the optical disc. There is a problem that a process for optimizing each optical disc is required.

For this reason, there is an example in which recording power information and / or manufacturing history information optimum for an optical disc is recorded in, for example, MO information in the recording area of the optical disc (see, for example, Patent Document 1).
In recent years, an optical disk has been required to increase its capacity in order to cope with a rapid increase in recording capacity required for information-related and broadcast-related equipment. For this reason, in order to increase the recording density, research on further shortening of the laser wavelength (reducing the diameter of the focused spot) and the use of super-resolution technology is being promoted, while reducing the track pitch and mark pit pitch. Mastering techniques such as electron beam exposure have been studied.

  For example, regarding the shortening of the laser wavelength, development of an apparatus using a blue-violet laser beam having a wavelength of 405 nm has already been advanced.

  In the invention disclosed in Patent Document 1, when recording information using an optical disc apparatus, an optical disc of the CD-MO format has an optimum recording power without being controlled by the structure or composition of the recording film. Can record information.

  However, when trying to record information at a higher density with a focused spot laser beam that has been made smaller by using a short-wavelength laser beam such as a blue-violet laser, it is optimal because of various factors other than recording power. There is a problem that cannot be recorded properly.

  For example, when a blue-violet laser beam having a wavelength of 405 nm is used, the wavelength of the laser beam emitted from the laser element and the divergence of the divergence angle of the emitted beam, the fluctuation of the wavelength of the laser beam accompanying the temperature change, or the optical of the objective lens It is well known that the characteristics of individual optical heads differ due to any or all of the effects such as characteristics, and the spot diameter of the laser light varies.

  An object of the present invention is to provide an optical disc and an optical disc apparatus capable of recording information under optimum conditions without being controlled by individual differences of optical heads that affect the state of a light beam applied to the optical disc.

  The present invention has been made on the basis of the above problems, and a light source that emits light of a predetermined wavelength, light from the light source is guided to a predetermined recording area of the recording medium, and reflected light reflected by the recording medium is reflected. An optical element having at least an objective lens to be taken out, and the intensity of the light depends on individual differences of the optical elements obtained by reproducing the reflected light, variations in the divergence angle of light from the light source, and individual differences of the light source Based on information recorded in the predetermined recording area of the recording medium including information on recording power, which is suitable for taking into account any or all of the differences in wavelength and fluctuations in wavelength due to temperature changes. The present invention provides an optical disc device characterized by having a light source driving device to be optimized.

  As described above in detail, the optical disc of the present invention has a recording area in which optimum conditions are recorded without being controlled by individual differences of optical heads that affect the state of the light beam applied to the optical disc. As a result, during the initial operation of the optical disc apparatus, the optical disc is irradiated with an optical beam that is optimal for the characteristics of the set optical disc, so that information can be stably recorded and reproduced or erased.

  In addition, since the optical disk apparatus has a program for referencing the recording area of the optimum condition recorded on the optical disk at the initial operation after the optical disk is set, the state of the light beam irradiated on the optical disk is set. Information can be recorded and reproduced or erased under optimum conditions without being controlled by the individual differences of the optical heads that have an effect. In addition, under the optimum conditions without being influenced by the characteristic difference of the optical head due to the change in the operating temperature of the apparatus, without being influenced by the individual difference of the optical head that affects the state of the light beam irradiated on the optical disc, Information can be recorded and reproduced or erased.

  Furthermore, according to the present invention, it is possible to widen the manufacturability of the optical head and the manufacturing margin of the optical disc, and to obtain an inexpensive optical disc apparatus and optical disc system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view illustrating a recording medium to which an embodiment of the present invention can be applied.

  As shown in FIG. 1, an optical disc 1 as a recording medium has a recording film on which information can be recorded, erased and reproduced by a beam spot obtained by condensing laser light having a wavelength of 405 nm, for example. 1 substrate 10, a second substrate 20 having a structure substantially equal to the first substrate, and an adhesive layer 30 for bonding the first substrate 11 and the second substrate 21. A center hole 2 having a diameter of 15 mm is formed at the center of the optical disc 1, that is, the first and second substrates. The diameters of the substrates 10 and 20 are 120 mm, and the total thickness of the disk 1 including the adhesive layer 30 is approximately 1.2 mm.

  The first and second substrates 10 and 20 have base materials 11 and 21, respectively, and an information recording surface 12 and an information recording surface 22 formed respectively. In addition, the 2nd board | substrate 20 is bonded together so that the 1st board | substrate 10 and the information recording surface 22 may become the same direction. Further, the adhesive layer 30 and the base material 11 of the first substrate 10 are given characteristics that allow at least laser light having a wavelength of 405 nm to pass through the recording layer 22 of the second substrate 20 with a predetermined intensity.

  For example, calibration and / or program memory area 3, lead-in area 4, memory area 5, and the like are arranged at predetermined positions in the area direction of first and second substrates 10 and 20 from the center hole 2 toward the outermost periphery. A lead-out area 6 is formed in order. The physical size of each area will be described by taking a disk having an outer diameter of 120 mm as an example. Each area has a diameter of 46 mm for calibration and / or program memory area 3, 50 mm for lead-in area 4, and memory area 5 Is 116 mm, and the lead-out area 6 is 118 mm.

  In the optical disc 1 described above, for example, in the lead-in area 4, the wavelength difference or temperature due to the variation in the divergence angle of the laser light emitted from the laser element when using a violet laser beam having a wavelength of 405 nm, or individual laser differences. Suitable recording power information that takes into account any or all of the effects of changes in the wavelength of the laser light accompanying the change or the optical characteristics of the objective lens of the optical disc apparatus, etc., is recorded in advance in the format shown in the following stage. Yes.

  Information on the characteristics of the optical head relating to the recording power will be described below with reference to FIG. 7, for example. RIM indicating the relationship between the numerical aperture NA of the objective lens used for the pickup of the optical disk apparatus and the wavelength λ of the laser light There is strength.

  The RIM intensity (Rim Intensity) is a value representing the light intensity at the aperture edge of the lens as a ratio (or percentage) with respect to the center intensity of the light beam, and is incident on the objective lens. This is one of the parameters representing the optical characteristics of the beam.

For example, in an optical disc apparatus, the diameter R of a light beam that can be focused on an optical disc by an objective lens is
R = 2 × f (RIM) × λ / NA
Is required. Here, f (RIM) represents a function for RIM. In addition, since the objective lens is generally annular, the light beam, particularly the laser light from the semiconductor laser element, is divergent and the cross-sectional beam (spot) shape is elliptical. If there is, the directionality is also defined by RIMx.

  As an example, when RIM (no directivity) = 0.6, wavelength λ = 405 nm, and NA = 0.65, the beam diameter R is R = 0.5260 μm. Further, when RIM (no directivity) = 0.7, wavelength λ = 405 nm, and NA = 0.65, R = 0.5218 μm.

  In the optical disk apparatus, since the light beam (laser light) from the semiconductor laser element is divergent and a collimator lens is used in addition to the objective lens, the value of RIM is the divergence angle of the laser light, It depends on the focal length of the collimating lens and the characteristics of the beam shaping prism described later.

  2 to 4 are schematic views for sequentially explaining steps of manufacturing the optical disc shown in FIG.

  First, as shown in FIG. 2A, a glass whose surface is polished and cleaned to a predetermined surface roughness is prepared as a master 301.

  Next, as shown in FIG. 2B, a photoresist 303 is applied to the surface of the glass master 301.

  Subsequently, as shown in FIG. 2 (c), exposure is performed with a laser beam having a predetermined wavelength, and physical information (header) and guide grooves (unevenness) are provided in the area corresponding to the memory area 5 with calibration and / or Alternatively, in the areas corresponding to the program memory area 3 and the lead-in area 4, although not described in detail, the initial information and the information on the recording power are recorded.

  Next, by developing the glass master 301 exposed with physical information, initial information, and information regarding recording power to remove the undeveloped portion of the photoresist, the unevenness as shown in FIG. 2D is obtained. .

  Thereafter, as shown in FIG. 2E, the stamper 311 is obtained by plating the glass master 301.

  Next, as shown in FIG. 3A, the stamper 311 is used as a mold, and injection molding is performed to form a resin molded plate (the base material 11 of the first substrate 10 and the second substrate 20 shown in FIG. 1). A substrate 21) is completed. The base materials 11 and 21 are made of, for example, polycarbonate or glass.

  In this way, the areas corresponding to the calibration and / or the program memory area 3 and the lead-in area 4 of the first and second base materials 10 and 20 correspond to the above-described initial information and information relating to the recording power. An unevenness or a pattern having a predetermined shape is formed at the same time.

  Hereinafter, as shown in FIG. 3B, a metal or alloy suitable for the recording film is formed on the molded plate (10 or 20) masked by the mask 321 except for the region to be the recording film (12, 22). By depositing the film to a predetermined thickness by sputtering or the like, the single substrate 10 or 20 before being bonded by the adhesive layer 30 is obtained.

  Subsequently, as shown in FIG. 4A, although not described in detail, an adhesive that becomes the adhesive layer 30 in a state where any one single substrate (20 or 10) is attached to the spinner turntable, For example, a predetermined amount of UV curable resin that cures when irradiated with ultraviolet rays is supplied, and the turntable is rotated at a predetermined number of revolutions, whereby an adhesive layer having a substantially uniform thickness, that is, UV, is formed on a single substrate. A thin layer of cured resin is obtained (see FIG. 4 (b)).

  Next, as shown in FIG. 4 (c), the single substrate to be bonded whose surface on which the recording surface (12 or 22) is formed is already set on the spinner on which the adhesive layer has been previously formed. Overlaid to face.

  In the following, although not shown, in the high-speed rotation of the spinner table (excess adhesive removal step), the excess of the adhesive positioned between the two substrates is removed, and as shown in FIG. 1), and the adhesive becomes the adhesive layer 30, whereby the optical disc 1 as shown in FIG. 1 is obtained.

  5 and 6 schematically illustrate an optical disk apparatus capable of recording information on or reproducing information from the optical disk described above with reference to FIG. 1 and an optical head incorporated in the optical disk apparatus.

  As shown in FIG. 5, in the optical head 110 of the optical disc apparatus 100, the light beam (laser light) from the light source, that is, the semiconductor laser element 11, is collimated by the collimating lens 112 and the cross-sectional beam shape is predetermined by the beam shaping prism 113. Changed to shape.

  The laser light whose beam shape has been shaped by the beam shaping prism 113 is guided to the optical disc 1 side by the beam splitter 114, reflected by the mirror 115, and redirected toward the optical disc 1.

  The laser beam directed to the optical disk 1 by the mirror 115 is converted into circularly polarized light by the quarter wavelength plate 116, given a predetermined focusing property by the objective lens 117, and applied to one of the recording surfaces 12 or 22 of the optical disk 1. Focused.

  When the information is recorded on the recording surface 12 or 22 of the optical disc 1 and the information is recorded on the recording surface, the reflected laser light whose reflectivity or polarization direction is changed by the information is returned to the objective lens 117. The polarization direction is rotated by approximately 90 ° by the / 4 wavelength plate 116 and returned to the mirror 115.

  The reflected laser light returned to the mirror 115 is reflected by the beam splitter 114 and directed by the mirror 118 in a predetermined direction.

  The reflected laser light whose traveling direction has been changed by the mirror 118 is given a predetermined imaging characteristic by the imaging lens 119, and then a focus error pattern capable of providing a predetermined imaging pattern used for focus error detection. The wavefront is converted by the generating element 120 so that a predetermined spot pattern can be generated, and an image is formed on the light receiving surface of the subsequent photodetector 121.

  Needless to say, various known methods can be used for the method of detecting the focus error and the tracking error, the pattern of the light receiving surface of the photodetector 121, signal processing, and the like.

  The focus error detection pattern and the tracking error detection pattern formed on the photodetector 121 are subjected to signal processing by the signal reproduction system shown in FIG. 6 as described below, and the position of the objective lens 117 is the recording surface of the optical disc 1. The focus is locked at a position where it is on-focused to either 12 or 22, and the center of the pit row of the track or information pit formed in advance on the recording surface 12 or 22 is coincident with the center of the laser beam. Tracking is controlled. Further, as will be described below, the reproduction signal is obtained by adding the output of the photodetector 121.

  FIG. 6 is a schematic diagram for explaining an example of a signal processing system that records information on the optical disk by the optical disk apparatus shown in FIG. 1 and the optical disk apparatus described above with reference to FIG.

  The photodetector 121 includes first to fourth region photodiodes 121A, 121B, 121C, and 121D. Outputs A, B, C and D of the respective photodiodes are amplified to predetermined levels by first to fourth amplifiers 221a, 221b, 221c and 221d, respectively.

  As for outputs A to D from the amplifiers 221a to 221d, A and B are added by the first adder 222a, and C and D are added by the second adder 222b.

  The outputs of the adders 222 a and 222 b are “added (subtracted) with (C + D) with the sign inverted to (A + B)” in the adder 223. As a result of addition (subtraction) by the adder 223, the position of the objective lens 117 is focused on a track (not shown) on the recording surface 12 or 22 of the optical disc 1 or a pit row (not shown) and a light beam focused by the objective lens 117. The focus error signal is supplied to the focus control circuit 231 as a focus error signal for matching the focal length, which is a distance.

  The adder 224 generates (A + C), and the adder 225 generates (B + D). The outputs of both adders, that is, (A + C) and (B + D) are input to the phase difference detector 232. The phase difference detector 232 is useful for obtaining an accurate tracking error signal when the objective lens 117 is lens-shifted.

  The sum of (A + B) and (C + D) is obtained by the adder 226 and supplied to the tracking control circuit 233 as a tracking error signal.

  (A + C) and (B + D) are further added by an adder 227, converted into an (A + B + C + D) signal, that is, a reproduction signal, and input to the buffer memory 234.

  Note that the intensity of the return light of the laser light emitted from the laser element 111 is input to the APC circuit 239. As a result, the power of the laser beam emitted from the laser element 111 is stabilized based on the recording data stored in the recording data memory 236.

  In the optical disc apparatus 100 having such a signal detection system, when the optical disc 1 is set on the turntable 131 and the optical head 110 is positioned at a recording / reproducing position (not shown), the optical disc device 100 stores in the ROM 240 under the control of the CPU 238. A predetermined initial routine is started in accordance with the initial program.

  For example, when a predetermined motor pulse is supplied from the motor driving circuit 235, the driving motor 141 is rotated at a predetermined speed, an access motor (not shown) is operated, and the optical head 110 is calibrated and / or programmed. The memory area 3 or the lead-in area 4 is moved to a position facing a predetermined position.

  Thereafter, a laser beam of reproduction power stabilized by the laser drive circuit 237 and the APC circuit 239 is emitted from the laser element 111 and recorded in the calibration and / or program memory area 3 or the lead-in area 4 of the optical disc 1. Information is read.

  At this time, when the above-described blue-violet laser beam having a wavelength of 405 nm is used, the variation in the divergence angle of the laser beam, the wavelength difference due to the individual difference of the laser or the change in the wavelength of the laser beam due to the temperature change, information on the RIM, etc. Various information is retrieved.

  Hereinafter, although detailed description is omitted, a signal reproducing operation, an erasing operation, or a recording operation is started. During the recording operation, the recording power optimized based on the above-described variation in the divergence angle of the laser beam, the wavelength difference due to the individual difference of the laser or the variation in the wavelength of the laser beam due to the temperature change, and information on the RIM Is output from the laser element 111 so that the optical disk 1 is irradiated with the laser beam.

  Incidentally, it is known that the laser light from the semiconductor laser element 111 described with reference to FIG. 5 has different divergence angles in the direction perpendicular to the horizontal direction of the bonding surface of the laser chip. For example, the divergence angle in the direction horizontal to the joint surface is 6 to 10 ° in full width at half maximum, and the divergence angle in the direction perpendicular to the full width at half maximum is 22 to 30 °.

  Further, as already described, the intensity of the laser light focused on the recording surface 12 or 22 of the optical disk 1 by the objective lens 117 is proportional to the numerical aperture NA of the objective lens 117 and the wavelength λ of the laser light, and the objective lens 117. Is affected by RIM due to the opening edge of In the optical disk device 101 described above, a collimating lens 112 is also a lens that should be considered for the influence of RIM.

  For example, as shown in FIG. 7, the relationship between the recording power and the CNR when information is recorded on an optical disk using optical heads having different RIM values is governed by the RIM described above.

  RIMt and RIMr in FIG. 7 are RIM values corresponding to the radial direction r and the tangential direction t of the disc.

  As apparent from FIG. 7, the difference in the RIM value of the optical head 110 causes a difference in the optimum recording power.

  For this reason, at least when information is recorded on the optical disc 1, information on the wavelength variation of the laser beam due to the above-described variation in the divergence angle of the laser beam, the wavelength difference due to the individual difference of the laser, or the temperature change, and information on the RIM. It is preferable to use a recording power optimized based on this.

  Accordingly, when information is recorded on the optical disc 1 or reproduced or erased by the optical disc apparatus 100, information on the disc and power recorded in advance on the optical disc 1, characteristics governed by the optical head 110 side, and disc side Read the related information such as characteristics, set the power for recording (including erasure or reproduction) based on at least the information, and control the laser beam (light beam) output from the laser element 111, The power of the light beam emitted from the objective lens can be optimized. By the way, the information recorded on the optical disc 1 in advance as described above is information on only the power of the light beam for recording, erasing or reproducing on the optical disc 1 corresponding to the individual difference of the optical head 110, even if the optical disc apparatus 100 is used. Thus, it may be recorded on the optical disc 1 in such a format that the relationship with the characteristics of the optical head 110 can be determined.

  Hereinafter, an example of information recorded on the optical disc will be described in order.

  When the stamper 311 described with reference to FIG. 2E is formed on the optical disc 1, it is formed in advance in a region corresponding to the lead-in area 4 with a predetermined recording data density as shown in FIG. The data arrangement structure is transferred.

  As shown in FIG. 9, the lead-in area 4 includes the system lead-in area (physical sector number [02 2640h] to [02 6AFFh] across the connection area (physical sector number [02 6AFFh] to [02 9A00h]). ] And a data lead-in area (from physical sector number [02 9A00h] to [03 0000h]).

  In the system lead-in area, a control data zone (physical sector number [02 4F00h] to [02 6700h]) is defined.

  The above-described system lead-in area, control data zone, and data lead-in area are transferred to the optical disc 1 in advance by the stamper 311 described above as a row of embossed pits.

  The track in the system lead-in area is a continuous spiral that goes around 360 °. The tracks in the data lead-in area, the data area, and the data lead-out area are continuous spirals that make a 360 ° round. The center of the track is the center of the pit.

  FIG. 10 shows an example of information recorded in the control data zone.

  For example, physical format information and disc manufacturer information are recorded in a predetermined order in the BP (Byte position) 401 as information content 402, and as described above, output from the laser element 111 (see FIG. 1). The power of the laser beam (light beam) can be optimized based on information recorded (transferred) in advance on the optical disc 1 side.

  11 to 14 are schematic diagrams for explaining information recorded in the system lead-in area, control data zone, and data lead-in area shown in FIG. The information described with reference to FIGS. 11 to 14 is recorded (transferred) continuously or in units obtained by dividing a BP (Byte position) 501 having a predetermined size at an arbitrary position. 11 to 14, in the BP column 501, the rows from “0” to “31” are read-only discs, discs on which information can be recorded only once (R type), and recording / rewriting (rewriting). The position of information that can be recorded is defined as an area in which information common to each of the possible RAM disks is recorded. On the other hand, with respect to the rows from “32” to “2047” in the BP column 501, the reproduction-only disk, the disk capable of recording information only once (R type), and the RAM disk capable of recording / reproducing (rewritable), respectively This is an area where special information given uniquely is recorded.

  In the BP column 501, the information about the speed is recorded in the downstream of the “31” row, for example, the “AZ (33)” row. The alphabet shown in the tenth place corresponds to the priority order of the recorded information, and is read according to the alphabetical order when the information in the lead-in area 4 is reproduced. In addition, when the first alphabet in the two-digit character string is an uppercase letter, the recorded information is assumed to be continuous according to the alphabetical order. On the other hand, if the alphabet shown at the top of the two-digit character string is a lower case letter, it indicates that another arbitrary information may be added before or after the alphabet.

  In the “BA (34)” line following the “AZ (33)” line, information on the Rim intensity (related to the tangential direction) is recorded. Subsequent to the “BA (34)” row, the “BB (35)” row records information on the Rim intensity (related to the radial (radial) direction).

  Hereinafter, the read power for the “BC (36)” row, the peak power for the land for the “BD (37)” row, the bias power 1 for the land for the “BE (38)” row, the “BF” The (39) "row records the bias power 2 for the land, and the" BG (40) "row records the bias power 3 for the land in order.

  Subsequently, the read power, peak power, bias power 1, bias power 2, bias power 3, and the like for the groove are sequentially recorded in the “Bn” row, the “BX” row, the “BY” row, and the “BZ” row. Has been.

  Hereinafter, between the “CA” line and the “CZ” line, the leading end pulse end time for the land, the multi-pulse duration for the land, the trailing end pulse start time for the land, and the like are recorded in order. Further, between the “DA” line and the “DZ” line, the leading end pulse end time for the groove, the multi-pulse duration for the groove, the trailing end pulse start time for the groove, and the like are recorded in order.

  Note that part of the control information recorded (transferred) in the system lead-in area of the optical disc described above, for example, a land described between the “CA (45)” line and the “DZ (92)” line. End pulse end time, multi-pulse duration for land, trailing pulse start time for land, leading pulse end time for groove, multi-pulse duration for groove, trailing pulse start time for groove , Etc. are compatible with Standard ECMA-330, which is a standard relating to a writable disk of the DVD standard, that is, a RAM disk, which is currently widely used. In addition, most of the control information described in some of the control information recorded from the “BA” line to the “BZ” line is also compatible with Standard ECMA-330, which is a standard for RAM disks. .

  15A shows recording data, FIG. 15B shows a recording waveform, and FIG. 15C shows a write pulse for recording the recording waveform shown in FIG. ing.

  On the optical disc 1, an NRZI recording waveform (FIG. 15 (b)) associated with recording data (FIG. 15 (a)), which is information to be recorded, has a write pulse as shown in FIG. 15 (c). Is recorded.

  The write pulse waveform shown in FIG. 15C corresponds to each recording condition described above with reference to FIGS. For example, the correspondence between each information recorded between the “CA” row and the “DZ” row in the BP column 501 and the light beam, that is, the writing pulse is shown.

  Explaining the main write pulse, the peak powers recorded in the “BD” row and the “Bn” row correspond to the peak power Ppp, respectively, except for the conditions for the land and the groove.

Similarly, the bias power 1 recorded in the “BE” row and the “BX” row corresponds to Pbp ₁ respectively. Hereinafter, the bias power 2 recorded in the “BF” row and the “BY” row corresponds to the PBP ₂ respectively, and the bias power 3 recorded in the “BG” row and the “BZ” row corresponds to the PBP ₃ respectively. The

The bias power 1 is used for a predetermined period up to the beginning of the next data following the _TLC representing the end of the 8T data, 3T data, and 2T data illustrated in FIGS. 15A and 15B. Is done. Similarly, bias power 2 are both level shown in FIG. 15 (a) illustrated 8T data in and (b), _T represents the termination of 3T data and 2T data _LC. Further, the bias power 3 is the level of multipulses in the 8T data and 3T data exemplified in FIGS. 15A and 15B. Therefore, the bias power 3 is not used for 2T data.

Further, the leading end pulses PFa (8T) and PFb (3T) indicating the writing (leading) of individual recording data are defined by the leading end pulse end time recorded in the “CA” line or the “DA” line. Similarly, the bias power 1 is determined by rear end pulses PLa (8T) and PLb () indicating the end (rear end) of individual recording data according to the rear end pulse start time recorded in the “CC” row or “DC” row. 3T) is defined. In the 2T system, since the leading pulse and the trailing pulse are represented as one peak pulse, the leading pulse and the trailing pulse do not exist, and a single pulse having the same waveform as the leading pulse is present. Subsequent to (Mono pulse), PBP ₃ (bias power 3) is used.

  Needless to say, the entire period between the leading edge pulse and the trailing edge pulse is shown as write pulses PWa, PWb,...

The waveform of the write pulse will be described in detail. As shown in FIG. 16, the difference A between the level of the bias power 1 and the level of the peak power is the power P ₁ , and the level of the peak power and the bias power 2 the difference B is a power P _2, the difference C is the power P ₃ of the level and the bias power 2 levels of peak power, and the difference D between the bias power 2 level and the bias power 1 level at power P _4, Each is shown. That is, the write pulse shown in FIG. 15 (c), by combining the first power P ₁ to the fourth power P ₄ described with reference to FIG. 16, it is readily provided.

  Note that “manufacturer information (manufacturer name)” recorded in the BP (Byte position) column 401 described above with reference to FIG. 10, for example, as the “1” row is the BP (Byte position) 501 shown in FIG. Are recorded as a predetermined code string between the “EA” line and the “FZ” line. In addition, as “information from the manufacturer”, for example, the difference in the wavelength of the light beam between the “GA” line and the “Gn” line indicates that information is recorded on the optical disk or reproduced or erased from the optical disk. As information when there is a large influence, etc., it is recorded as the power of a recording, erasing or reproducing light beam corresponding to the wavelength. Between the “GA” line and the “Gn” line, the power of the recording, erasing or reproducing light beam corresponding to both parameters is related to the difference between the RIM value specific to the optical head and the wavelength of the light beam. Is recorded.

  Incidentally, a lead-in area is also provided in an optical disc (information recording medium) of the DVD standard that is already widely used. In the DVD-ROM, which is a read-only recording medium among the DVD standard optical disks, the pit depth is λ / ((λ) when the wavelength of the light beam is λ and the refractive index of the disk (resin material) is n. 4n) is said to be the optimum depth.

  Similarly, in a DVD-RAM that is a rewritable information recording medium, the pregroove depth is set as a condition for minimizing crosstalk (leakage into a reproduction signal) from a recording mark of an adjacent track in the data area. Λ / (5n) to λ / (6n) is said to be the optimum depth.

  Therefore, in the DVD-RAM, the pit depth of the embossed lead-in area is also set to λ / (5n) to λ / (6n).

  From a pit having a depth of λ / (4n) or λ / (5n) to λ / (6n) (because the depth is sufficiently deep), a reproduction signal having a sufficiently large amplitude can be obtained.

  On the other hand, in a DVD-R (write-once type in which information can be recorded only once), the groove depth in the data area is shallower than that in DVD-RAM, so that an emboss lead-in with the same depth is used. There is a problem that a reproduction signal having a large amplitude cannot be obtained from the pits in the area, and reproduction is not stable.

  Therefore, in order to guarantee a stable reproduction signal from the lead-in area of the write-once information recording medium while ensuring format compatibility for any read-only / write-once / rewritable information recording medium, A system lead-in area is provided, and the track pitch and the shortest pit pitch here are made larger than the track pitch and the shortest pit pitch (shortest mark pitch) in the data lead-in area and data area. There are features.

  At present, in order to obtain a reproduction signal from the DVD standard optical disc, the reproduction signal is detected (binarization processing for the analog reproduction signal is output) by the level slice method.

  However, even in the currently used DVD standard optical disc, the shortest pit pitch of pits having fine irregularities or the shortest mark pitch of recording marks formed by the change in optical characteristics of the recording film is shown in FIG. The reproduction signal amplitude from the shortest pit pitch / shortest mark pitch is very small because it is close to the cutoff (cutoff) frequency of the OTF (Optical Transfer Function) characteristic of the objective lens 117 used in the optical head 110 described in (1).

  It has been proposed to secure the recording density by reducing the shortest pit pitch / shortest mark pitch. However, in the level slicing method, the shortest pit pitch / shortest mark pitch in which the pitch is packed more than the DVD standard optical disc. It is impossible to obtain a reproduction signal from In addition, for the reasons described above, the DVD-R disc is already packed with the shortest pit pitch, so that it is difficult to obtain a stable reproduction signal from the lead-in area.

In this embodiment, in order to solve the conflicting problems,
[Α] The lead-in area is divided into a system lead-in area and a data lead-in area, and the track pitch and the shortest pit pitch of both are changed.
[Β] In the system lead-in area, the track pitch and the shortest pit pitch are greatly expanded to reduce the decrease in the reproduction signal amplitude from the shortest pit pitch relative to the reproduction signal amplitude from the least-sparse pit pitch. Enables signal reproduction from the system lead-in area in a write-once information recording medium with a shallow pit depth by facilitating signal reproduction.
[Γ] Aiming at increasing the storage capacity of the information recording medium itself, in order to increase the recording density of the lead-in area and data area, the shortest pit pitch / shortest mark pitch is narrowed and the reproduction signal is detected (binary from the analog signal). Adopt PRML method instead of current level slice method
[Δ] A modulation method suitable for improving the recording density by reducing the shortest pit pitch / shortest mark pitch is adopted.

  In other words, the minimum number of consecutive “0” s after modulation (the value of d in the (d, k) constraint after modulation) is adopted in the current DVD using the modulation rule of d = 1 for d = 2. It is a combination of four devices.

  By receiving the system lead-in area and the data lead-in area separately, it is possible to change both the track pitch and the shortest pit pitch. In the system lead-in area, the track pitch and the minimum pit pitch are changed. It can be roughened.

  As described above, in the optical disc 1 of the present invention, information indicating the light beam power for recording corresponding to the RIM value of the optical head 110 is a predetermined area of the optical disc 1, for example, calibration and / or program memory area. 3 or the lead-in area 4 is recorded in advance, so that the power information for recording according to the initial program stored in the ROM 240 is obtained by the signal processing system shown in FIG. Information can be recorded.

However, in practice, it may not be necessary to represent the RIM value and power function in detail, for example,
RIMr ≦ 0.65, RIMt ≦ 0.65 → Pw = 4.8 mW,
RIMr> 0.65, RIMt> 0.65 → Pw = 4.4 mW
Even with such information, there is information on the light beam power for recording that can provide optimum conditions without being controlled by individual differences of the optical head that affect the state of the light beam irradiated on the optical disk. It only has to be recorded.

The information recorded on the optical disk may be a function representing the relationship of the optimum power with respect to the RIM of the optical head, and may be, for example, an LUT (Look Up Table) format as shown in [Table 1] below. .

  The information recorded on the optical disc, that is, the control information may be a compressed file in a format that can be easily decompressed (decompressed only by the optical disc apparatus).

  If the difference in the wavelength of the light beam output from the optical head 110 has a great influence on recording or reproducing or erasing information from the optical disk, the recording, erasing or reproducing light corresponding to the wavelength is used. The beam power is preferably recorded in advance on the disk 1. Further, when the influence of the difference between the RIM value of the optical head 110 and the wavelength of the light beam is large, it is preferable to record in advance the power of the recording, erasing or reproducing light beam corresponding to both parameters on the disk 1. . By the way, the optical disk apparatus may be used at a high temperature or a low temperature. In general, the wavelength of a laser increases as the temperature rises. Therefore, the characteristics of the optical head 110 may change depending on the temperature. In addition, the optical beam power for recording, erasing or reproducing the optical disc may also be temperature dependent. In this case, the power of the recording, erasing or reproducing light beam may be recorded in advance on the disk 1 in accordance with the temperature. When the influence of the parameters of RIM, wavelength, and apparatus temperature is large as described above, the power of the recording, erasing or reproducing light beam may be recorded on the disk 1 in advance on the optical disk corresponding to all parameters.

  Further, in the optical disc apparatus 100 shown in FIG. 6, the ROM 240 can absorb the above-described differences in the wavelength of the laser beam that cannot be optimized only by the unique information on the optical disc side and the difference in the RIM value that is a factor on the optical disc apparatus side. Although an example in which a program for reading out “information” is included has been described, the “calibration and / or program memory area 3 or lead-in area 4” of the optical disc 1 cannot be optimized only by the above-mentioned “specific information on the optical disc side”. It is also possible to simultaneously record a program for reading “information capable of absorbing the difference in the laser light wavelength and the difference in the RIM value that is a factor on the optical disk apparatus side”.

  Needless to say, the information recorded in advance in a predetermined area of the optical disk may be RIM or laser power or erasing power during reproduction with respect to a difference in wavelength.

  As described above, the light beam power for recording that can absorb the difference in the wavelength of the laser beam, the fluctuation in the wavelength, and the difference in the RIM value, which is a factor on the optical disc apparatus side, cannot be optimized only by the unique information of the optical disc. Information can be recorded more optimally on the optical disc. In addition, stable reproduction and reliable erasure are realized when reproducing and erasing information from the optical disk.

  It should be noted that the area on the optical disc in which information that can absorb the difference in wavelength of the laser light that cannot be optimized only by the unique information on the optical disc side and the difference in RIM value that is a factor on the optical disc apparatus side is recorded on the optical disc Considering a routine for reproducing information from the optical disk by the apparatus, a lead-in area where information is first read is suitable, for example, as long as the information can be read before the information is actually recorded. Needless to say, any part of the optical disk may be used. Also, the information that can absorb the difference in the wavelength of the laser light and the difference in the RIM value, which is a factor on the optical disk apparatus side, is recorded for each disk by, for example, a recording laser light after the disk is formed. It goes without saying.

  Furthermore, information that can absorb the difference in the wavelength of the laser beam, the variation in wavelength, and the difference in the RIM value that is a factor on the optical disc apparatus side that cannot be optimized only by the unique information on the optical disc side is, for example, The second layer may be divided and recorded. For example, the first layer absorbs the difference in the wavelength of the laser beam that cannot be optimized only by the unique information on the optical disc side or the difference in the RIM value that is a factor on the optical disc apparatus side. Possible information is recorded at the same time and its position is recorded. For example, the second layer cannot be optimized only by the unique information on the optical disc side. It goes without saying that information itself that can absorb fluctuations in values may be recorded.

  As described above, at least information such as the RIM value of the optical head and the recording power for recording, reproducing, or erasing on the disk may be recorded at least on the optical disk. In this case, it is possible to reduce the information recorded on the disc.

  That is, when recording / reproducing with the optical disk device, by reading the RIM value recorded on the disk and the recording conditions, etc., and comparing the RIM value recorded on the disk with the RIM value of the optical disk device, It is possible to derive optimum recording conditions. This is because the recording power and the like correspond to the beam diameter to be recorded and reproduced, and the beam diameter corresponds to the RIM value. Therefore, the recording power can be converted from the difference in the RIM value.

  The present invention is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the scope of the invention when it is implemented. Moreover, each embodiment may be implemented in combination as appropriate as possible, and in that case, the effect of the combination can be obtained.

1 is a schematic diagram illustrating an optical disc to which an embodiment of the present invention is applied. Schematic explaining the process of manufacturing the optical disk shown in FIG. Schematic explaining the process following the process of manufacturing the optical disk shown in FIG. Schematic explaining the process following the process of manufacturing the optical disk shown in FIG. FIG. 2 is a schematic diagram for explaining an example of an optical head of an optical disc apparatus that records or reproduces information on the optical disc shown in FIG. 1. FIG. 6 is a schematic diagram illustrating an example of a signal processing system (optical disk device) that processes a signal obtained by the optical head illustrated in FIG. 5. 6 is a graph for explaining a relationship between a RIM value and recording power in an optical disc apparatus. Schematic explaining the recording data density of each area | region of an optical disk. Schematic explaining the arrangement and data structure of the data lead-in area and system lead-in area of an optical disc. FIG. 10 is a schematic diagram for explaining an example of data arrangement in a control data zone in the lead-in area shown in FIG. 9. Schematic explaining an example of information recorded in the lead-in area shown in FIG. Schematic explaining an example of the information recorded following the recorded information shown in FIG. Schematic explaining an example of information recorded subsequent to the recorded information shown in FIG. FIG. 14 is a schematic diagram illustrating an example of information recorded following the recorded information illustrated in FIG. 13. Schematic diagram for explaining the relationship between the information on the intensity of the light beam recorded in the lead-in area shown in FIG. 11 to FIG. 14 and the light beam (write pulse) output for actually recording information on the optical disc . Schematic diagram for explaining the relationship between the information on the intensity of the light beam recorded in the lead-in area shown in FIG. 11 to FIG. 14 and the light beam (write pulse) output for actually recording information on the optical disc .

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical disk, 3 ... Calibration and / or program memory area, 4 ... Lead-in area, 10 ... 1st board | substrate, 12 ... Recording surface, 20 ... 2nd board | substrate, 22 ... Recording surface, 30 ... UV curable resin Layer (adhesive layer), 110 ... optical head, 111 ... laser element (light source), 112 ... collimating lens (optical element), 117 ... objective lens (optical element), 237 ... laser drive circuit, 239 ... APC circuit, 240 ... ROM (program holding device).

Claims (5)

A light source that emits light of a predetermined wavelength;
An optical element including at least an objective lens that guides light from the light source to a predetermined recording area of the recording medium and extracts reflected light reflected by the recording medium;
The intensity of the light, the individual difference of the optical element obtained by reproducing the reflected light, the variation in the divergence angle of the light from the light source, the wavelength difference due to the individual difference of the light source, the wavelength accompanying the temperature change A light source driving device that optimizes based on information recorded in the predetermined recording area of the recording medium, including information relating to recording power, in consideration of any or all of the fluctuations of
An optical disc apparatus comprising:   2. The optical disc apparatus according to claim 1, wherein the information is information relating to a factor that causes the recording power to vary depending on the entire optical element. A light source that emits light of a predetermined wavelength;
At least a collimating lens of an optical element that guides and focuses light from the light source to a predetermined recording area of the recording medium and an objective lens,
Information on the intensity of the light beam for recording, reproducing, and erasing on the recording medium defined by the focal length of the collimating lens, the wavelength and divergence angle of the light of the light source, the NA of the objective lens, and the focal length A program holding device in which a control program to be read from the recording medium is recorded;
A light source driving device that reads the intensity of the light from the recording medium according to a control program recorded in the program holding device, and optimizes the intensity of the light from the light source;
An optical disc apparatus comprising:   4. The optical disc according to claim 3, wherein the program holding device holds control information for reading the information recorded in a predetermined area of the recording medium from an arbitrary position of the optical disc. apparatus.   5. The optical disc apparatus according to claim 4, wherein the control information is attached to initial control information.

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