JP2005339671A - Recording condition deciding method, recording method, optical disk apparatus, program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decide an appropriate recording condition when ternary or more multi-valued information is recorded in an optical disk. <P>SOLUTION: Test writing of the same multilevel data is performed continuously at the prescribed test region so that length of a track in the tangential direction is longer than a spot diameter of a light spot formed in a track at the time of reproduction (step 407), and appropriate recording power and recording strategy are obtained based on a level of a reproduction signal from its test region (step 409-423). Thereby, influence of interference between codes appears clearly in the reproduction signal from the test region. Thus, recording power and recording strategy when influence between codes becomes small are obtained according to the level of the reproduction signal from the test region. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

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

  In this optical disc apparatus, laser light is emitted from a light source, a minute spot is formed on the recording surface of the optical disc on which spiral or concentric tracks are formed, information is recorded and erased, and reflected light from the recording surface is reflected. Based on this, information is reproduced.

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

  In the optical disc apparatus, prior to recording information, a test writing area called PCA (Power Calibration Area) is formed so that a mark area and a space area having a target length are formed at the target position of the optical disc. Trial writing is performed to obtain the optimum recording power. This process is called an OPC (Optimum Power Control) process.

  By the way, the information amount of the content tends to increase year by year, and further increase of the information amount that can be recorded on one optical disk is expected. One way to increase the amount of information that can be recorded on an optical disc is to convert the information into a combination of three or more numerical values and write it to the optical disc. (For example, see Patent Documents 1 to 9). Hereinafter, conversion of information into a combination of three or more types of numerical values is referred to as multi-value conversion, and multi-value data is referred to as multi-value data or multi-value level data. In addition, such a recording method for recording information with multiple values is called a multi-value recording method.

  In this multi-level recording method, as in the binary recording method, it is important to obtain an appropriate recording power and recording strategy prior to information recording in order to improve the recording quality (for example, Patent Documents). 10). In the multi-value recording method, the recording linear density is higher than in the binary recording method, and the size of a unit area (cell) in which one multi-valued data is recorded is smaller than the spot diameter of the light spot. Is likely to occur. However, in the method disclosed in Patent Document 10, since intersymbol interference is not taken into consideration, if the cell size is further reduced in the future, the obtained recording power and recording strategy are not always appropriate. May not be a strategy.

JP 2001-184647 A JP 2002-25114 A Japanese Patent Laid-Open No. 2002-83445 JP 2002-334438 A JP 2002-352428 A JP 2002-352429 A JP 2002-367182 A JP 2003-151137 A JP 2003-141725 A JP 2003-132536 A

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

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

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

  According to the first aspect of the present invention, there is provided a recording condition determining method for determining a recording condition for recording information multi-valued in three or more values on a spiral or concentric track formed on a recording surface of an optical disc. The same multi-value level data is written on a predetermined test area continuously so that the length in the tangential direction of the track is longer than the spot diameter of the light spot formed on the track during reproduction. And a second step of acquiring an appropriate recording power and recording strategy based on a reproduction signal from the test area.

  According to this, the same multi-level data is trial-written in a predetermined test area continuously so that the length in the tangential direction of the track is longer than the spot diameter of the light spot formed on the track during reproduction. (First step) Based on the level of the reproduced signal from the test area, an appropriate recording power and recording strategy are acquired (second step). In this case, since the length of the test area is longer than the spot diameter, and a plurality of the same multilevel data is written in the test area, the influence of intersymbol interference on the reproduction signal from the test area Will appear clearly. Therefore, it is possible to acquire the recording power and the recording strategy when the influence of the intersymbol interference is reduced based on the level of the reproduction signal from the test area. Accordingly, it is possible to determine an appropriate recording condition for recording information multi-valued to three or more values on an optical disc.

  In this case, as in the recording condition determining method according to claim 2, in the second step, the recording power when the difference between the maximum value and the minimum value in the level of the reproduction signal is equal to or less than a predetermined reference value and A recording strategy can be obtained.

  In this case, the reference value can be recorded on the optical disc as in the recording condition determining method according to claim 3.

  The recording condition determining method according to claim 2, further comprising a third step of determining the type of the optical disc as in the recording condition determining method according to claim 4, wherein the reference value is based on the determination result. Thus, it can be selected from preset values according to the type of the optical disc.

  In each of the recording condition determining methods according to claims 2 to 4, as in the recording condition determining method according to claim 5, the reference value is a multi-valued number α (α ≧ of the multi-valued information). 3) and the level difference DR between the reproduction signal level of the unrecorded area and the reproduction signal level of the area where the maximum mark is formed, and γ for which a value of 1 or more is set, {| DR | / It can be a value calculated by {γ · (α-1)}. In this specification, the “maximum mark” includes a mark having the largest area, a mark having the deepest depth, a mark having the largest area and the deepest depth, and the like.

  In this case, as in the recording condition determination method according to claim 6, the multilevel data is multilevel data corresponding to the maximum mark, and in the second step, a reproduction signal from the test area is recorded. The reference value can be calculated using.

  In the recording condition determining method according to claim 1, when the average value of the reproduction signal level falls within a preset range in the second step as in the recording condition determining method according to claim 7. Recording power and recording strategy can be obtained.

  The recording condition determining method according to claim 1, wherein, in the second step, the maximum value or the minimum value in the level of the reproduction signal and the average level of the reproduction signal are determined as in the recording condition determination method according to claim 8. It is possible to acquire the recording power and the recording strategy when the difference between the values becomes equal to or less than a preset reference value.

  In each of the recording condition determination methods according to claims 1 to 8, as in the recording condition determination method according to claim 9, the test area has a number of the multi-level data recorded in the test area, Using the cell length S in the test area and the spot diameter 2R of the light spot, a value obtained by adding 2 to an integer value obtained by rounding up the decimal point of the calculation result of (2R ÷ S) is set. Can be.

  In this case, as in the recording condition determining method according to claim 10, the level of the reproduction signal from the test area is determined from both ends of the test area among a plurality of multilevel data recorded in the test area. Each of them can be the level of a reproduction signal of multi-level data excluding the number of multi-level data obtained by rounding down the decimal point of the calculation result of (R ÷ S).

  The invention according to claim 11 is a recording method for recording information multi-valued into three or more values on a spiral or concentric track formed on the recording surface of an optical disc, wherein the information is multi-valued. A recording method including a step of recording information on an optical disc using the recording power and the recording strategy acquired by the recording condition determining method according to any one of the above.

  According to this, since information is recorded on the optical disc using the recording power and the recording strategy acquired by the recording condition determination method according to any one of claims 1 to 10, the multi-value is increased to three or more values. The recorded information can be recorded on the optical disc with high recording quality.

  The invention according to claim 12 is an optical disc apparatus capable of recording information multi-valued into three or more values on a spiral or concentric track formed on the recording surface of the optical disc, wherein the same multi-value is recorded. Test writing means for continuously writing the level data in a predetermined test area so that the length in the tangential direction of the track is longer than the spot diameter of the light spot formed on the track during reproduction; Obtaining means for obtaining an appropriate recording power and recording strategy based on a level of a reproduction signal from the area; and a processing device for recording information on the optical disc using the obtained recording power and recording strategy. An optical disk device.

  According to this, the test writing means continuously performs the predetermined test so that the same multi-value level data is longer in the tangential direction of the track than the spot diameter of the light spot formed on the track during reproduction. Trial writing is performed in the area, and an appropriate recording power and recording strategy are acquired by the acquiring unit based on the level of the reproduction signal from the test area. Then, information is recorded on the optical disk by the processing device using the recording power and the recording strategy acquired by the acquisition means. In this case, since the length of the test area is longer than the spot diameter, and a plurality of the same multilevel data is written in the test area, the influence of intersymbol interference on the reproduction signal from the test area Will appear clearly. Therefore, the acquisition means can acquire the recording power and the recording strategy when the influence of intersymbol interference is reduced. Therefore, as a result, it is possible to record information multi-valued to three or more values on an optical disc with high recording quality.

  In this case, as in the optical disk device according to claim 13, the acquisition means calculates the recording power and the recording strategy when the difference between the maximum value and the minimum value in the level of the reproduction signal is equal to or less than a predetermined reference value. Can be acquired.

  In this case, the reference value can be recorded on the optical disc as in the optical disc device according to the fourteenth aspect.

  The optical disc apparatus according to claim 13, further comprising a discriminating unit for discriminating the type of the optical disc as in the optical disc device according to claim 15, wherein the reference value is based on a discrimination result by the discriminating unit. The value can be selected from preset values according to the type of the optical disc.

  In each of the optical disk devices according to claims 13 to 15, as in the optical disk device according to claim 16, the reference value is a multi-valued number α (α ≧ 3) of the multi-valued information, Using the level difference DR between the reproduction signal level of the unrecorded area and the reproduction signal level of the area where the maximum mark is formed, and γ for which a value of 1 or more is set, {| DR | / {γ · ( α-1)}.

  In this case, as in the optical disc device according to claim 17, the multi-level data is multi-level data corresponding to the maximum mark, and the acquisition unit uses a reproduction signal from the test area. The reference value can be calculated.

  In this case, as in the optical disc device according to claim 18, the acquisition means can further record the calculated reference value on the optical disc.

  13. The optical disc apparatus according to claim 12, wherein, as in the optical disc apparatus according to claim 19, the acquisition means performs recording power and recording when the average value of the reproduction signal level falls within a preset range. A strategy can be obtained.

  In the optical disk device according to claim 12, as in the optical disk device according to claim 20, the acquisition unit has a difference between a maximum value or a minimum value in the level of the reproduction signal and an average level of the reproduction signal in advance. It is possible to acquire the recording power and the recording strategy when the reference value is below the set reference value.

  In each of the optical disk devices according to claims 12 to 20, as in the optical disk device according to claim 21, the test area has a number of the multi-level data recorded in the test area in the test area. Using the cell length S and the spot diameter 2R of the light spot, it is set to be a value obtained by adding 2 to an integer value obtained by rounding up the decimal point of the calculation result of (2R ÷ S). Can do.

  In this case, as in the optical disc device according to claim 22, the level of the reproduction signal from the test area is determined from each of both ends of the test area among a plurality of multilevel data recorded in the test area. The level of the reproduction signal of the multilevel data excluding the number of multilevel data that has been rounded down after the decimal point of the calculation result of (R ÷ S).

  The invention according to claim 23 is a program used in an optical disc apparatus capable of recording information multi-valued into three or more values on a spiral or concentric track formed on a recording surface of an optical disc, A procedure in which the same multi-level data is successively written in a predetermined test area so that the length in the tangential direction of the track is longer than the spot diameter of the light spot formed on the track during reproduction; A procedure for acquiring an appropriate recording power and recording strategy based on a level of a reproduction signal from the test area; and a procedure for recording information on the optical disc using the acquired recording power and recording strategy. This is a program to be executed by a control computer of the optical disc apparatus.

  According to this, when the program of the present invention is loaded into a predetermined memory and the start address is set in the program counter, the control computer of the optical disc apparatus forms the same multi-level data on the track during reproduction. Test writing is performed continuously in a predetermined test area so that the length in the tangential direction of the track is longer than the spot diameter of the light spot to be recorded, and the appropriate recording power and Get a recording strategy. Then, information is recorded on the optical disc using the acquired recording power and recording strategy. In this case, since the length of the test area is longer than the spot diameter, and a plurality of the same multilevel data is written in the test area, the influence of intersymbol interference on the reproduction signal from the test area Will appear clearly. Therefore, it is possible to acquire the recording power and the recording strategy when the influence of the intersymbol interference is reduced based on the level of the reproduction signal from the test area. Therefore, as a result, it is possible to record information multi-valued to three or more values on an optical disc with high recording quality.

  A twenty-fourth aspect of the present invention is a computer-readable recording medium on which the program according to the twenty-third aspect is recorded.

  According to this, since the program according to claim 23 is recorded, it is possible to record information multi-valued to three or more values on an optical disc with high recording quality by causing the computer to execute the program. Become.

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

  An optical disk device 20 shown in FIG. 1 includes a spindle motor 22 for rotating the optical disk 15, an optical pickup device 23, a seek motor 21 for driving the optical pickup device 23 in the sledge direction, a laser control circuit 24, An encoder 25, a drive control circuit 26, a reproduction signal processing circuit 28, a buffer RAM 34, a buffer manager 37, an interface 38, a flash memory 39, a CPU 40, a RAM 41, and the like are provided. Note that the arrows in FIG. 1 indicate the flow of typical signals and information, and do not represent the entire connection relationship of each block. The optical disc apparatus 20 corresponds to a multi-value recording method, and the recording data (information) is multi-valued to 8 values (0 to 7) as an example. Furthermore, in this embodiment, an information recording medium corresponding to a wavelength of about 405 nm is used as the optical disc 15 as an example.

  In the multi-value recording system, as shown in FIG. 2 as an example, the track is virtually divided into a plurality of regions (cells) for each predetermined length (here, S) with respect to the tangential direction of the track. The One cell stores one multilevel data (multilevel data). When the value of the multilevel data is 1 to 7, a recording mark having an area corresponding to the value is formed at the center of the cell. Note that when the value of the multi-value data is 0, no recording mark is formed.

  In the portion where the recording mark is formed, the reflectance of the laser beam decreases as the area of the recording mark increases. Therefore, the reproduction signal (RF signal) generated from the laser beam reflected on the recording surface of the optical disc is as shown in FIG. As shown in FIG. 5, when the multi-value data is 0, the maximum level (L0) is obtained, and when the multi-value data is 7, the minimum level (L7) is obtained. The signal levels when the multi-value data is 1 to 6 are L1 to L6.

  The optical pickup device 23 irradiates a recording surface on which a spiral or concentric track of the optical disk 15 rotated by a spindle motor 22 is formed with laser light and receives reflected light from the recording surface. Device. As shown in FIG. 3 as an example, the optical pickup device 23 includes a light source unit 51, a collimating lens 52, a beam splitter 54, an objective lens 60, a detection lens 58, a light receiver PD, and a drive system (focusing actuator, tracking actuator ( All are omitted))) and the like.

  The light source unit 51 includes a semiconductor laser LD as a light source that emits laser light having a wavelength of about 405 nm. In the present embodiment, the maximum intensity emission direction of the laser beam emitted from the light source unit 51 is defined as the + X direction. The collimating lens 52 is disposed on the + X side of the light source unit 51 and makes the light beam emitted from the light source unit 51 substantially parallel light.

  The beam splitter 54 is disposed on the + X side of the collimating lens 52 and branches the light beam (return light beam) reflected by the optical disk 15 in the −Z direction. The objective lens 60 is disposed on the + X side of the beam splitter 54 and condenses the light beam transmitted through the beam splitter 54 on the recording surface of the optical disc 15.

  The detection lens 58 is disposed on the −Z side of the beam splitter 54, and condenses the return light beam branched in the −Z direction by the beam splitter 54 on the light receiving surface of the light receiving device PD. The light receiver PD includes a plurality of light receiving elements (or light receiving regions) that output signals including wobble signal information, reproduction data information, focus error information, track error information, and the like, as in a normal optical disk device. Yes.

  The focusing actuator (not shown) is an actuator for minutely driving the objective lens 60 in the focus direction that is the optical axis direction of the objective lens 60. The tracking actuator (not shown) is an actuator for minutely driving the objective lens 60 in a tracking direction which is a direction orthogonal to the tangential direction of the track.

  The operation of the optical pickup device 23 configured as described above will be briefly described. The light beam emitted from the light source unit 51 is converted into substantially parallel light by the collimator lens 52 and then enters the beam splitter 54. The light beam that has passed through the beam splitter 54 is condensed as a minute spot on the recording surface of the optical disk 15 via the objective lens 60. The light beam reflected by the recording surface of the optical disk 15 is converted into a substantially parallel light by the objective lens 60 as a return light beam and enters the beam splitter 54. The returned light beam branched in the −Z direction by the beam splitter 54 is received by the light receiver PD via the detection lens 58. In the light receiving device PD, a current signal corresponding to the amount of received light is generated by photoelectric conversion, and the current signal is output to the reproduction signal processing circuit 28.

  Returning to FIG. 1, the reproduction signal processing circuit 28 acquires a servo signal (focus error signal, track error signal, etc.), address information, a synchronization signal, an RF signal, and the like based on the output signal of the light receiver PD. . The servo signal obtained here is output to the drive control circuit 26, the address information is output to the CPU 40, and the synchronization signal is output to the encoder 25. Further, the reproduction signal processing circuit 28 performs decoding processing, error detection processing, and the like on the RF signal. When an error is detected, the reproduction signal processing circuit 28 performs error correction processing, and then plays back the buffer via the buffer manager 37 as reproduction data. Store in the RAM 34.

  The drive control circuit 26 generates a drive signal for the tracking actuator for correcting the positional deviation of the objective lens 60 with respect to the tracking direction based on the track error signal from the reproduction signal processing circuit 28, and generates a focus error signal. Based on this, a driving signal for the focusing actuator for correcting the focus shift of the objective lens 60 is generated. Each drive signal generated here is output to the optical pickup device 23. Thereby, tracking control and focus control are performed. The drive control circuit 26 generates a drive signal for driving the seek motor 21 and a drive signal for driving the spindle motor 22 based on an instruction from the CPU 40. Each drive signal is output to the seek motor 21 and the spindle motor 22, respectively.

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

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

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

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

  The flash memory 39 includes a program area and a data area. In the program area of the flash memory 39, a program including a program according to the present invention written in a code readable by the CPU 40 is stored. In the data area, the light emission characteristics of the semiconductor laser LD, the recording conditions including the recording power and the recording strategy, and the like are stored. The recording conditions are acquired in advance by experiments, simulations, theoretical calculations, empirical rules, and the like for each type of optical disc (for example, manufacturer name, lot, etc.) and for each recording speed.

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

<Recording process>
Next, processing when the optical disc apparatus 20 configured as described above receives a recording request command from the host apparatus 90 will be described with reference to FIG. The flowchart in FIG. 4 corresponds to a series of processing algorithms executed by the CPU 40.

  When a recording request command is received from the host device 90, the head address of a program corresponding to the flowchart of FIG. 4 (hereinafter referred to as “recording processing program”) is set in the program counter of the CPU 40, and the recording process starts. Note that the type of the optical disk 15 is determined when the optical disk 15 is set in the optical disk device 20, notified to the laser control circuit 24, the reproduction signal processing circuit 28, and the like, and already stored in the RAM 41. .

  In the first step 401, a signal for driving the spindle motor 22 according to the recording speed is output to the drive control circuit 26, and the reproduction signal processing circuit 28 is notified that the recording request command from the host device 90 has been received. To do. Further, it instructs the buffer manager 37 to store user data (recording data) received from the host device 90 in the buffer RAM 34.

  In the next step 403, when it is confirmed that the optical disk 15 is rotating at a predetermined linear velocity (or angular velocity), servo-on is set for the drive control device 26. Thereby, tracking control and focus control are performed as described above. Note that tracking control and focus control are performed as needed until the recording process is completed.

  In the next step 405, recording conditions such as recording power and recording strategy are set. This recording condition is extracted from the data area of the flash memory 39 according to the type and recording speed of the optical disk 15. If no corresponding recording condition is found, the default recording condition stored in the data area is used. In addition, when the recording condition is recorded on the optical disc 15, the recording condition may be used.

  In the next step 407, a test pattern composed of a plurality of identical multi-value data is recorded in the test area provided on the optical disc 15 under the recording conditions set in step 405. That is, test writing is performed.

  The size of this test area will be described. Here, as an example, the number β of cells constituting one test area is set so as to satisfy the following expression (1). In this equation (1), when the spot diameter (diameter) in the tangential direction of the track of the light spot formed on the track during reproduction is 2R, an integer value obtained by rounding up the decimal point of the calculation result of 2R / S A. For example, when S = 0.24 (μm) and 2R = 0.54 (μm), β = 5. In this case, the number of cells constituting the test area is five.

  β = A + 2 (1)

  In each cell constituting the test area, multi-value data “7” corresponding to the maximum mark is recorded (see FIG. 5). That is, the test pattern is composed of five pieces of multi-value data “7”. In the present embodiment, the same test pattern is repeated three times as an example in order to increase accuracy (see FIG. 6). In FIG. 6, an unrecorded area longer than the beam diameter is provided before and after each area where the test pattern is recorded, but it is not essential to provide an unrecorded area. Further, the test area may be outside the data area (inner side or outer side from the data area), or may be inside the data area.

  In the next step 409, each test area is reproduced (see FIG. 6).

  In the next step 411, the reproduction signal in the test area is sampled at timings (T1 to T5) corresponding to the center position of each cell, and the signal level for each cell is detected (FIGS. 7A to 7). (See (C)).

  In the next step 413, the signal level of the unrecorded area is detected. Here, the signal level of the unrecorded area between the test areas is detected.

  In the next step 415, a reference value Q for evaluating the reproduction signal in the test area is calculated based on the following equation (2). Here, DR is the difference between the reproduction signal level in the unrecorded area and the reproduction signal level in the area where the maximum mark is recorded, α is a multi-value (here, 8), and γ is a value greater than 1. Preferably, 2 ≦ γ ≦ 100.

  In the present embodiment, the multi-value data recorded in the test area is the multi-value data “7” corresponding to the maximum mark, and there is an unrecorded area between the test areas. The DR can be obtained from the reproduced signal in the unrecorded area and the reproduced signal in the test area.

  As for γ, if the value is increased, the recording quality can be further improved. However, if the value is increased too much, excessive evaluation is performed. The value is determined. That is, γ is a value (coefficient) that defines the tolerance of variations in the reproduction signal level. For example, when the number β of cells constituting one test area is very large (for example, 100 or more), the detection data regarding the level variation amount in the reproduction signal is highly reliable, and therefore γ≈1 may be used. When β is relatively small (for example, less than 100), it is preferable to satisfy γ ≧ 2 because the detection data regarding the level variation amount in the reproduction signal is not sufficiently reliable. In the present embodiment, it is assumed that the value of γ is obtained in advance by experiments or the like and stored in the flash memory 39. If the value of γ is recorded on the optical disk 15, that value may be used.

  Q = | DR | / {γ · (α-1)} (2)

  In the next step 417, the maximum value and the minimum value of the signal level are obtained for each test area. However, at this time, the cell data of “the number obtained by rounding down the decimal point of the calculation result of (R ÷ S)” from the head and the tail of each test area is not used. Here, since the number obtained by rounding down the decimal point of the calculation result of (R ÷ S) is 1, the maximum value and the minimum value are obtained from the data of the three cells in the center, that is, the sampling data at timings T2, T3, and T4. . In the present embodiment, since three test patterns are recorded, three maximum values and three minimum values are obtained. Therefore, an average value of the three maximum values is set as a new maximum value, and an average value of the three minimum values is set as a new minimum value. Then, the difference (referred to as δ) between the new maximum value and the new minimum value is calculated. The maximum value and the minimum value do not include abnormal values due to defects.

  In the next step 419, it is determined whether or not δ is less than or equal to the reference value Q.

  Here, for example, as shown in FIG. 7B or FIG. 7C, when the reproduction signal level is greatly inclined, δ exceeds the reference value Q, and the determination in step 419 is denied. The process proceeds to step 421. That is, the fact that the reproduction signal level is greatly inclined indicates that the amount of intersymbol interference differs depending on the recording position.

  In this step 421, at least one of the recording power and the recording strategy is adjusted according to the difference between δ and the reference value Q. Then, the process returns to step 407.

  Thereafter, the processes in steps 407 to 421 are repeated until the determination in step 419 is affirmed.

  For example, as shown in FIG. 7A, when the reproduction signal level is substantially flat, δ is equal to or less than the reference value Q, the determination at step 419 is affirmed, and the routine proceeds to step 423. That is, the fact that the reproduction signal level is almost flat indicates that the amount of intersymbol interference is uniform regardless of the recording position.

  In this step 423, the recording power and recording strategy at that time are determined as appropriate recording power and recording strategy. Information regarding the recording power and the recording strategy determined here is notified to the laser control circuit 24. As a result, the laser control circuit 24 generates an appropriate drive signal.

  In the next step 425, an instruction is given to record information on the calculated reference value on the optical disk 15.

  In the next step 427, the drive control circuit 26 is instructed so that a light spot is formed before the target position. Thereby, the seek operation of the optical pickup device 23 is performed. If the seek operation is unnecessary, the process here is skipped.

  In the next step 429, recording of user data is permitted. As a result, user data is recorded on the optical disc 15 under appropriate recording conditions via the encoder 25, the laser control circuit 24, the optical pickup device 23, and the like.

  In the next step 431, it is determined whether or not user data recording is completed. If it is not completed, the determination here is denied and the determination is made again after a predetermined time has elapsed. If completed, the determination here is affirmed and the routine proceeds to step 433.

  In step 433, the drive control circuit 26 is instructed to turn off the servo. Then, the recording process ends.

  As is clear from the above description, in the optical disc apparatus 20 according to the present embodiment, the test writing unit and the acquisition unit are realized by the CPU 40 and the program executed by the CPU 40. That is, the trial writing means is realized by the processing of step 407 in FIG. 4, and the acquisition means is realized by the processing of steps 409 to 423 in FIG. It should be noted that at least a part of each means realized by processing according to the program by the CPU 40 may be configured by hardware, or all may be configured by hardware.

  Further, the processing device is realized by the encoder 25, the laser control circuit 24, the optical pickup device 23, the CPU 40, and a program executed by the CPU 40.

  In the present embodiment, the program of the present invention is executed in the recording processing program among the programs stored in the flash memory 39. That is, a test writing procedure is executed by a program corresponding to the process of step 407 in FIG. 4, and a procedure acquired by a program corresponding to the processes of steps 409 to 423 in FIG. 4 is executed, corresponding to the process of step 429. The recording procedure is executed by the program.

  In the recording process, the recording condition determination method and the recording method according to the present invention are implemented. That is, the first process of the recording condition determination method is performed in the process of step 407 in FIG. 4, the second process of the recording condition determination method is performed in the processes of steps 407 to 423 in FIG. 4, and the recording is performed in the process of step 429. A method recording step is performed.

  As described above, according to the optical disc apparatus 20 according to the present embodiment, before recording user data, the same multi-value data (multi-value level data) is a spot of a light spot formed on a track during reproduction. Trial writing is continuously performed in a predetermined test area so that the length in the tangential direction of the track becomes longer than the diameter, and the difference between the maximum value and the minimum value in the reproduction signal from the test area is equal to or less than the reference value Q. The recording power and the recording strategy are obtained. In this case, since the length of the test area is longer than the spot diameter and a plurality of identical multi-value data is written in the test area, the influence of intersymbol interference on the reproduced signal from the test area Will appear clearly. Therefore, the acquired recording power and recording strategy become recording conditions when the influence of intersymbol interference is reduced. Accordingly, it is possible to determine an appropriate recording condition for recording information multi-valued to three or more values on an optical disc.

  In addition, since information is recorded on the optical disc under the recording conditions when the influence of intersymbol interference is reduced, it is possible to record information multi-valued to three or more values on the optical disc with high recording quality. .

  In addition, since the reference value Q is calculated using the reproduction signal in the test area, the influence of intersymbol interference can be accurately evaluated.

  Further, since the calculated reference value Q is recorded on the optical disc 15, it can be used when the optical disc 15 is loaded again.

  In the above embodiment, the case where one test area is composed of five cells has been described. However, the present invention is not limited to this. What is necessary is just to be comprised by the number of cells more than the said (beta) value. For example, FIG. 8 (A) and FIG. 8 (B) show reproduction signals when one test area is composed of 10 cells (cells A to J). Here, FIG. 8A shows a reproduction signal when the recording power and the recording strategy are appropriate, and FIG. 8B shows a reproduction signal when the recording power and the recording strategy are inappropriate.

  By the way, if one test area is composed of three cells smaller than the value of β as shown in FIG. 9, for example, sampling is performed as shown in FIGS. 10 (A) and 10 (B). Since the signal level at the timings T1 and T3 is not sufficiently lowered, the reproduction signal level is the same even though the same recording mark is formed in each cell (cell A, cell B, cell C). Must not. Therefore, it is not possible to correctly evaluate whether the recording power and the recording strategy are appropriate.

  Further, in the above-described embodiment, the case where the same test pattern is repeated for test writing three times has been described. However, the present invention is not limited to this. For example, the test pattern may be test-written only once. It may be changed according to required accuracy and allowable processing time.

  Further, in the above embodiment, the case where an optical disk is used in which the signal level of the reproduction signal decreases as the area of the recording mark increases, but conversely, the signal level of the reproduction signal increases as the area of the recording mark increases. Such an optical disk may be used.

  Moreover, although the said embodiment demonstrated the case where information was multi-valued to 8 values (0-7), it is not limited to this. What is necessary is just to be multi-valued more than three values.

  In the above embodiment, the case of S = 0.24 (μm) and 2R = 0.54 (μm) has been described. However, the present invention is not limited to this.

  In the above embodiment, the case where the recording mark having the area corresponding to the multi-value data is formed in the cell has been described. However, the present invention is not limited to this. For example, the recording mark having the depth corresponding to the multi-value data is provided. It may be formed in a cell. Furthermore, recording marks having an area and depth corresponding to the multi-value data may be formed in the cell.

  Further, in the above embodiment, the case where the reference value Q calculated based on the above equation (2) is used when determining whether the recording power and the recording strategy are appropriate is not limited thereto. For example, a value obtained by dividing the reproduction signal level in the unrecorded area by the experience value may be used as the reference value.

<< Variation of recording process >>
In the above embodiment, whether or not the recording power and the recording strategy are appropriate is determined based on the difference between the maximum value and the minimum value of the reproduction signal level. It may be used to determine whether the recording power and the recording strategy are appropriate. The process and operation of the CPU 40 in the recording process in this case will be described with reference to the flowchart of FIG.

  In the first steps 501 to 511, processing similar to the processing in steps 401 to 411 is performed.

  In the next step 513, an average value (m) of the signal level detected in step 511 is calculated. However, data of cells corresponding to “the maximum integer value smaller than R / S” from the beginning and the end of the test area are not used. In this case, since the maximum integer value smaller than R / S = 1, the average value of the data of the three cells in the center, that is, the sampling data at timings T2, T3, and T4 is obtained.

  In the next step 515, it is determined whether or not the average value m is not less than a preset lower limit value and not more than a preset upper limit value. If the average value m is included between the lower limit value and the upper limit value, the determination here is affirmed and the routine proceeds to step 517.

  In the next steps 517 to 521, the difference δ between the reference value Q and the maximum value and the minimum value in the reproduction signal level is calculated in the same manner as the processing in steps 413 to 417.

  In the next step 523, it is determined whether or not δ is equal to or less than the reference value Q. If δ is not less than or equal to the reference value Q, the determination here is denied and the routine proceeds to step 525.

  In step 525, the same processing as that in step 421 is performed. Then, the process returns to step 507.

  In step 515, if the average value m is less than the lower limit value or exceeds the upper limit value, the determination in step 515 is denied and the process proceeds to step 525.

  In step 523, if δ is equal to or smaller than the reference value Q, the determination in step 523 is affirmed, and the routine proceeds to step 527.

  In steps 527 to 533, processing similar to that in steps 423 to 429 is performed.

  In the next step 535, it is determined whether or not the recording of user data is completed. If it is not completed, the determination here is denied and the determination is made again after a predetermined time has elapsed. If completed, the determination here is affirmed and the routine proceeds to step 537.

  In step 537, the drive control circuit 26 is instructed to turn off the servo. Then, the recording process ends.

  Also in this modification, user data is recorded under appropriate recording conditions, as in the above embodiment. Note that the determination based on the difference δ between the maximum value and the minimum value may be performed prior to the determination based on the average value m.

  Further, in the above embodiment and the modification, in order to determine whether or not the recording power and the recording strategy are appropriate, instead of the difference δ between the maximum value and the minimum value of the reproduction signal level, the reproduction signal level The difference between the maximum value or the minimum value and the average level, and the standard deviation of the reproduction signal level may be used. However, in this case, a reference value different from the reference value Q is used.

  Also, the multi-value data “1” is written in the first test area, the multi-value data “7” is written in the second test area, and the reproduction signal level (average value) of the first test area is written. ) (Referred to as S1), at least one of the reproduction signal level (average value) (referred to as S2) of the second test area, and the difference (absolute value) between the reproduction signal level S1 and the reproduction signal level S2. Based on this, it may be determined whether or not the recording power and the recording strategy are appropriate. In this case, as the reference value, a value stored in the data area of the flash memory 39 or a value recorded on the optical disk 15 may be used.

  Further, when a plurality of types of determination are performed as processing for determining whether or not the recording power and the recording strategy are appropriate, the order may be interchanged.

  In the above embodiment and the modification, the case where the reference value Q is calculated each time using the reproduction signal level of the unrecorded area and the reproduction signal level of the test area has been described. However, the present invention is not limited to this. Absent. For example, the reference value Q calculated in advance using the reproduction signal level of the unrecorded area and the reproduction signal level of the area where the multilevel data “7” is recorded may be used. Further, when the reference value Q is recorded on the optical disc, the reference value Q may be used. Also, a correspondence table between the optical disc type and the reference value Q may be created in advance and stored in the flash memory 39. In this case, the reference value Q corresponding to the type of the optical disc 15 is extracted (selected) from the correspondence table.

  In the above embodiment and the modification, the case where the multi-value data “7” is used as the multi-value data constituting the test pattern has been described, but not limited to this, the multi-value data “1” to “7” is used. Any of these may be used. However, when the multi-value data constituting the test pattern is any of multi-value data “1” to “6”, the reference value Q acquired in advance is used.

  Also, by inserting a test pattern into user data, it is possible to adjust the recording power and the recording strategy while recording the user data. So-called running OPC becomes possible. In the above embodiment, the case where the recording mark is not formed when the value of the multi-value data is 0 has been described. However, when the value of the multi-value data is 0 and the multi-value data is 1. A recording mark smaller than this recording mark may be formed.

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

  In the above embodiment, the case where the optical disc 15 is an information recording medium corresponding to light having a wavelength of about 405 nm has been described. However, the present invention is not limited to this, and for example, a commercially available write-once type or rewritable type is used. The information recording medium may be used.

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

1 is a block diagram showing a configuration of an optical disc device according to an embodiment of the present invention. It is a figure for demonstrating multi-value information. It is a figure for demonstrating the structure of the optical pick-up apparatus in FIG. It is a flowchart for demonstrating a recording process. It is a figure for demonstrating one test area | region. It is a wave form diagram for demonstrating the reproduction signal of a test area | region. FIGS. 7A to 7C are waveform diagrams for explaining the reproduction signal of one test area. FIG. 8A and FIG. 8B are waveform diagrams for explaining the reproduction signal when the test area is composed of 10 cells. It is a figure for demonstrating the test area | region comprised by three cells. FIGS. 10A and 10B are waveform diagrams for explaining a reproduction signal in the test area of FIG. It is a flowchart for demonstrating the modification of a recording process.

Explanation of symbols

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

Claims (24)

A recording condition determination method for determining a recording condition when recording information multi-valued in three or more values on a spiral or concentric track formed on a recording surface of an optical disc,
A first step of continuously writing the same multilevel data in a predetermined test area so that the length in the tangential direction of the track is longer than the spot diameter of the light spot formed on the track during reproduction. When;
And a second step of obtaining an appropriate recording power and recording strategy based on the level of the reproduction signal from the test area.   2. The recording according to claim 1, wherein in the second step, a recording power and a recording strategy are acquired when a difference between a maximum value and a minimum value in the level of the reproduction signal is equal to or less than a predetermined reference value. Condition determination method.   The recording condition determination method according to claim 2, wherein the reference value is recorded on the optical disc. A third step of determining the type of the optical disc;
3. The recording condition determining method according to claim 2, wherein the reference value is selected from values set in advance according to the type of the optical disk based on the determination result.   The reference value includes a multi-valued number α (α ≧ 3) of the multi-valued information and a level difference DR between a reproduction signal level of an unrecorded area and a reproduction signal level of an area where a maximum mark is formed. 5. The value calculated by {| DR | / {γ · (α-1)} using γ for which a value of 1 or more is set. The recording condition determination method according to one item. The multi-level data is multi-level data corresponding to the maximum mark,
6. The recording condition determining method according to claim 5, wherein, in the second step, the reference value is calculated using a reproduction signal from the test area.   2. The recording condition determination method according to claim 1, wherein, in the second step, a recording power and a recording strategy when the average value of the reproduction signal level falls within a preset range are obtained.   In the second step, obtaining a recording power and a recording strategy when a difference between a maximum value or a minimum value in the level of the reproduction signal and an average level of the reproduction signal is equal to or less than a preset reference value. The recording condition determining method according to claim 1, wherein the recording condition is determined.   In the test area, the number of the multi-level data recorded in the test area is calculated by (2R ÷ S) using the cell length S in the test area and the spot diameter 2R of the light spot. The recording condition determination method according to claim 1, wherein the recording condition determination method is set to be a value obtained by adding 2 to an integer value obtained by rounding up a fractional part.   The level of the reproduction signal from the test area is the number obtained by rounding down the decimals of the calculation result of (R ÷ S) from both ends of the test area among the plurality of multilevel data recorded in the test area. 10. The recording condition determining method according to claim 9, wherein the level of the reproduction signal of the multi-level data excluding the multi-level data is the level of the reproduction signal. A recording method for recording information multi-valued into three or more values on a spiral or concentric track formed on a recording surface of an optical disc,
A recording method including a step of recording information on an optical disk using the recording power and the recording strategy acquired by the recording condition determination method according to claim 1. An optical disc apparatus capable of recording information multi-valued into three or more values on a spiral or concentric track formed on a recording surface of an optical disc,
Test writing means for continuously writing the same multi-level data in a predetermined test area so that the length in the tangential direction of the track is longer than the spot diameter of the light spot formed on the track during reproduction. When;
Obtaining means for obtaining an appropriate recording power and recording strategy based on the level of the reproduction signal from the test area;
And a processing device for recording information on the optical disc using the acquired recording power and recording strategy.   13. The optical disc apparatus according to claim 12, wherein the acquisition unit acquires a recording power and a recording strategy when a difference between a maximum value and a minimum value in the level of the reproduction signal is equal to or less than a predetermined reference value. .   14. The optical disc apparatus according to claim 13, wherein the reference value is recorded on the optical disc. A discriminating means for discriminating the type of the optical disc;
14. The optical disk apparatus according to claim 13, wherein the reference value is selected from values set in advance according to the type of the optical disk, based on a determination result by the determination unit.   The reference value includes a multi-valued number α (α ≧ 3) of the multi-valued information and a level difference DR between a reproduction signal level of an unrecorded area and a reproduction signal level of an area where a maximum mark is formed. 16. The value calculated by {| DR | / {γ · (α-1)} using γ for which a value of 1 or more is set. The optical disc device according to one item. The multi-level data is multi-level data corresponding to the maximum mark,
The optical disk apparatus according to claim 16, wherein the acquisition unit calculates the reference value using a reproduction signal from the test area.   18. The optical disc apparatus according to claim 17, wherein the acquisition unit further records the calculated reference value on the optical disc.   13. The optical disc apparatus according to claim 12, wherein the acquisition unit acquires a recording power and a recording strategy when the average value of the reproduction signal level is within a preset range.   The acquisition means acquires a recording power and a recording strategy when a difference between a maximum value or a minimum value in the level of the reproduction signal and an average level of the reproduction signal is equal to or less than a preset reference value. The optical disc apparatus according to claim 12.   In the test area, the number of the multi-level data recorded in the test area is calculated by (2R ÷ S) using the cell length S in the test area and the spot diameter 2R of the light spot. 21. The optical disc apparatus according to claim 12, wherein the optical disc apparatus is set to be a value obtained by adding 2 to an integer value obtained by rounding up a fractional part.   The level of the reproduction signal from the test area is the number obtained by rounding down the decimals of the calculation result of (R ÷ S) from both ends of the test area among the plurality of multilevel data recorded in the test area. The optical disk apparatus according to claim 21, wherein the level of the reproduction signal of the multi-level data excluding the multi-level data is the level of the reproduction signal. A program used for an optical disc apparatus capable of recording information multi-valued into three or more values on a spiral or concentric track formed on the recording surface of an optical disc,
A procedure in which the same multi-level data is successively written in a predetermined test area so that the length in the tangential direction of the track is longer than the spot diameter of the light spot formed on the track during reproduction;
Obtaining appropriate recording power and recording strategy based on the level of the reproduction signal from the test area;
A program for causing a control computer of the optical disc apparatus to execute a procedure for recording information on the optical disc using the acquired recording power and recording strategy. A computer-readable recording medium on which the program according to claim 23 is recorded.

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