JP3836862B2 - Information recording and playback method - Google Patents

Description

  The present invention relates to an improvement in signal processing in information recording / reproduction using an information medium such as an optical disk. More specifically, the present invention relates to a method for evaluating signal quality in information recording / reproduction, improvement of an information recording / reproduction system, improvement of a recording compensation method, and an information medium used in these methods / systems.

  There is an information recording system using an optical disc (Patent Document 1). The outline of this system is as follows. That is, information recorded on the optical disk is reproduced as a weak analog signal using a PUH (pickup head). The reproduced analog signal is amplified by a preamplifier and becomes a sufficient signal level, and then becomes a binary signal corresponding to a mark / space by a level slicer.

On the other hand, a channel clock that is phase-synchronized with the binarized signal is generated by a PLL (phase lock loop) circuit. The waveform correction amount is calculated by the parameter calculation means from the binarized signal and the channel clock. A recording waveform pulse is generated from the waveform correction amount, the recording data, and the reference clock by the recording waveform generation means. Laser light corresponding to the recording waveform pulse is emitted from the PUH to the optical disk, and information corresponding to the recording data is recorded on the optical disk as marks / spaces.
JP 2000-90436 A

  In the technique of Patent Document 1, the waveform compensation amount is calculated from the phase difference between the rising edge or falling edge of the binarized signal and the channel clock. This is effective when the slice method is adopted as a method for identifying the reproduced signal content, but cannot be applied to a method for identifying the reproduced signal from the amplitude value of the reproduced signal sample as in the integral detection method. In particular, when the recording density is high as in an optical disk system using a blue laser, it is not sufficient to adopt a slice method as an identification method, and high-grade identification like a PRML (Partial Response and Maximum Likelihood) method. A method is required. This PRML method is also a method for discriminating from the amplitude value of the reproduction signal sample, and cannot be dealt with by the technique of Patent Document 1. That is, in identifying the reproduction signal from the amplitude value of the reproduction signal sample, the quality of the reproduction signal cannot be properly evaluated, or an appropriate waveform correction amount cannot be calculated.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a method capable of appropriately evaluating the quality of a reproduction signal in identifying the reproduction signal from the amplitude value of the reproduction signal sample. .

  Another object is to provide a system or method capable of calculating an appropriate waveform correction amount for identifying a reproduction signal from the amplitude value of the reproduction signal sample.

  Another object of the present invention is to provide an information medium used in the above method or system.

  In order to achieve the above object, in a signal quality evaluation method according to an embodiment of the present invention, a predetermined reproduction signal (E200), a first pattern corresponding to a signal waveform pattern of the reproduction signal (E200), and the first pattern Any pattern other than one pattern and corresponding to the signal waveform pattern of the reproduction signal (E200) is used. Here, first, a distance difference D (=) between a distance Eo between the reproduction signal (E200) and the first pattern and a distance Ee between the reproduction signal (E200) and the arbitrary pattern. Ee-Eo; Equation 18) is obtained. Next, the distribution of the distance difference D (FIG. 5) is obtained for a plurality of samples of the reproduction signal. Next, based on the ratio between the average M of the obtained distance difference D and the standard deviation σ of the distribution of the obtained distance difference D, the quality evaluation parameter (M / σ; Equation 19) of the reproduction signal (E200) is Determined. Then, the quality of the reproduction signal (E200) is determined from the index value (evaluation index value Mgn in Expression 19) represented by the quality evaluation parameter (M / σ).

  Alternatively, in the information recording / reproducing system according to one embodiment of the present invention, a method (PRML method) of identifying the signal content from the amplitude value of the signal sample is used. In this system, a first pattern including a code bit string “10” or “01”, a second pattern whose location corresponding to the code bit string “10” or “01” is “11”, and the code bit string Pattern providing means (pattern memory 212) for providing a third pattern whose location corresponding to “10” or “01” is “00”; and the first information using a predetermined information recording medium (optical disc 100) Recording / reproducing means (200, 230) for recording / reproducing the pattern; and the reproduction signal (E200) of the first pattern by the recording / reproducing means (200, 230) is identified as corresponding to the second pattern. Recording compensation amount (100) for the information recording medium (100) from the first probability (left in FIG. 5) and the second probability (right in FIG. 5) identified as corresponding to the third pattern. Compensation amount calculation means (202 to 224) for calculating (WC) is used.

  Alternatively, the recording compensation method according to one embodiment of the present invention includes a predetermined reproduction signal (E200), a first pattern corresponding to a signal waveform pattern of the reproduction signal (E200), and other than the first pattern, The second pattern corresponding to the signal waveform pattern of the reproduction signal (E200) and the third pattern corresponding to the signal waveform pattern of the reproduction signal (E200) other than the first and second patterns are used. It is used for recording information on an information recording medium (optical disc 100) or reproducing recorded information. In this method, a first distance E1 (Equation 2) between the reproduction signal (E200) and the first pattern and a second distance E2 between the reproduction signal (E200) and the second pattern. (Equation 3) and a third distance E3 (Equation 4) between the reproduction signal (E200) and the second pattern are obtained. Next, a first distance difference D2 between the first distance E1 and the second distance E2 = E2−E1 (Expression 7), and a second distance between the first distance E1 and the third distance E3. The distance difference D3 = E3-E1 (Formula 8) is obtained. Next, the distribution of the first distance difference D2 (left in FIG. 5) and the distribution of the second distance difference D3 (right in FIG. 5) are obtained for a plurality of samples of the reproduction signal. Next, the average M2 of the obtained first distance difference D2, the standard deviation σ2 of the distribution of the obtained first distance difference D2 (left of FIG. 5), the average M3 of the obtained second distance difference D3 and the obtained value. Further, a standard deviation σ3 of the distribution of the second distance difference D3 (right of FIG. 5) is obtained. Next, a recording compensation parameter (Ec in Equation 13; unit is Euclidean distance) is obtained from the relationship of (σ2 * M3 + σ3 * M2) / (σ2 + σ3). Based on the recording compensation parameter (Ec) thus obtained, a signal recording waveform (b to d in FIG. 8) for the information recording medium (100) is compensated (adaptive control of the recording waveform).

  As described above, according to the embodiment of the present invention, the quality of the reproduction signal can be appropriately evaluated. Alternatively, an appropriate waveform correction amount can be obtained.

  Hereinafter, a signal quality evaluation method, an information recording / reproducing system, a recording compensation method, and an information medium according to various embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram for explaining the configuration of an information recording / reproducing system (a first embodiment) according to an embodiment of the present invention.

  In FIG. 1, information recorded as a mark / space (not shown) on the optical disc 100 is read as a weak analog reproduction signal E200 via a pickup head (PUH) 200. The analog reproduction signal E200 is amplified to a sufficient level by the preamplifier 202. The amplified analog reproduction signal E202 is converted into a digital reproduction signal E204 by the A / D converter 204. The digital reproduction signal E204 is appropriately delayed by a delay unit 206, and the delayed signal E206 is input to each of the distance calculators 208A to 208C.

  On the other hand, several types of preset patterns are registered in the pattern discriminator 210. When the recording data RD to be recorded on the optical disc 100 and the internal registered pattern match (or correspond), the pattern discriminator 210 indicates which pattern the matching (or corresponding) pattern is registered to. The pattern instruction signal E210a is output (for example, if there are three patterns to be used, the signal E210a may have 2 bits).

  The pattern memory 212 outputs three types of binary patterns (referred to as pattern 1, pattern 2, and pattern 3, respectively) registered therein according to the contents of the pattern instruction signal E210a from the pattern discriminator 210. The three types of output binary patterns (pattern 1, pattern 2, and pattern 3) are supplied to ideal signal calculators 214A to 214C, respectively.

  In the ideal signal calculators 214A to 214C, an ideal reproduction signal (hereinafter referred to as an ideal signal) corresponding to the PR characteristic (partial response characteristic) to be used from the supplied binary pattern (pattern 1, pattern 2, pattern 3). The relation between the signal pattern of the ideal signal and the reproduction signal will be described later with reference to FIG. 4) E214A to E214C.

  The created ideal signals E214A to E214C are supplied to distance calculators 208A to 208C, respectively. Each distance calculator 208 </ b> A to 208 </ b> C receives a signal E <b> 206 that is appropriately delayed by a delay unit 206. The amount of delay by the delay unit 206 is set so that the ideal signals E214A to E214C and the reproduction signal E204 are in phase.

  The distance calculators 208A to 208C calculate distances (Euclidean distances to be described later) between the ideal signals E214A to E214C and the reproduction signal E204 (the calculated distances are E1, E2, and E3, respectively). The calculated distances E1 and E2 are input to the subtractor 216, and the calculated distances E1 and E3 are input to the subtractor 218. The subtractor 216 calculates the difference between the distance E2 and the distance E1 (E2-E1), and the subtractor 218 calculates the difference between the distance E3 and the distance E1 (E3-E1). The calculated differences (E2-E1) and (E3-E1) are stored in the distance difference memories 220 and 222, respectively.

  Here, where the differences (E2-E1 and E3-E1) are stored in the distance difference memories 220 and 222 depends on the memory select signal E210b output from the pattern discriminator 210 (that is, the memories 220 and 220). The write / read address to 222 can be determined by the signal E210b).

  When a predetermined amount of data is recorded and reproduced from the optical disc 100, the parameter calculation unit 224 calculates the waveform compensation amount WC of the recording waveform from the data stored in the distance difference memories 220 and 222. That is, the parameter calculation unit 224 performs a predetermined parameter calculation based on the distance difference data E220 (= E2-E1) and E222 (= E3-E1) read from the distance difference memories 220 and 222, and the waveform compensation amount WC is output. The waveform compensation amount WC, the reference clock RC, and the recording data RD are supplied to the recording waveform creation unit 230. The recording waveform creation unit 230 generates a recording waveform pulse E230 that is appropriately waveform compensated (adaptively controlled) from the supplied reference clock RC, recording data RD, and waveform compensation amount WC. The PUH 200 records information on the optical disc 100 using the generated recording waveform pulse E230.

  For example, the recording waveform creation unit 230 has a reference clock RC with a period T as shown in FIG. 7A and an NRZI (Non-Return to Zero Inverted) with a length nT as shown in FIG. ) When a waveform (corresponding to recording data RD) is given, a recording pulse E230 having a waveform as shown in FIG. 7C is generated. Further, the recording waveform creation unit 230 is configured to increase or decrease the pulse width of, for example, the first pulse (first pulse) of the recording pulse E230 shown in FIG. 7C according to the given waveform compensation amount WC. Yes. As described above, a specific example of the internal configuration of the recording waveform creation unit 230 that generates the recording waveform E230 that changes in accordance with the reference clock RC, the recording data RD, and the waveform compensation amount WC is disclosed in, for example, Japanese Patent Laid-Open No. 2000-90436. There is a specific disclosure as “recording waveform creation means” (however, the contents of the waveform correction amount WCA in the embodiment of Japanese Patent Laid-Open No. 2000-90436 and the waveform compensation amount WC in the embodiment of the present invention are different).

  How the waveform compensation amount WC in the embodiment of the present invention is obtained will be described later with reference to FIG. 6 and others as appropriate. Further, how the waveform of the recording waveform pulse E230 is compensated by the obtained waveform compensation amount WC will be described later with reference to FIGS.

  FIG. 2 is a diagram illustrating the configuration of the ideal signal calculator 214 (each 214A to 214C) used in the system (apparatus) of FIG. Here, the configuration of the ideal signal calculator 214 when the PR (1, 2, 2, 1) characteristic is used as the partial response characteristic is illustrated. The calculator 214 is a general 4-tap FIR (Finite Impulse Response) filter, and tap coefficients thereof are 1, 2, 2, and 1.

  Specifically, in the ideal signal calculator 214, delay devices 2141 to 2143 having a delay time of 1T (corresponding to one cycle of the reference clock RC) are connected in series, and a predetermined pattern (patterns 1 and 2) is connected to the first delay device 2141. Or the bit string E212 of 3) is input. The input bit string is delayed by 1T in synchronization with the reference clock RC by the subsequent delay units 2142 to 2143. The bit string E212 before the delay is input to the adder 2140 with a coefficient “1”. The bit string delayed by 1T by the delay unit 2141 is multiplied by the coefficient “× 2” by the coefficient unit 2144 and input to the adder 2140. The bit string further delayed by 1T by the delay unit 2142 is multiplied by the coefficient “× 2” by the coefficient unit 2145 and input to the adder 2140. The bit string further delayed by 1T by the delay unit 2143 is input to the adder 2140 with a coefficient “1”. In this way, the ideal signal E214 (E214A, E214B, or E214C) subjected to the calculation corresponding to the PR (1, 2, 2, 1) characteristic can be obtained from the adder 2140.

  For example, when a series (E212) of “00010000” is input to the ideal signal calculator 214, the output is “00012210”. Similarly, when “000110000” is input, “000134310” is output, when “0001110000” is input, “000135531” is output, and when “00011110000” is input, “00013565310” is output. In the PR (1, 2, 2, 1) characteristic, the output (E214) of the FIR filter is one of seven levels “0, 1, 2, 3, 4, 5, 6”.

  Hereinafter, for convenience, a sequence in which n code bits “1” continue is expressed as an nT mark, and a sequence in which n code bits “0” continue is expressed as an nT space. Here, when an RLL (1, 7) code (RLL: Run-Length Limited) is used as a modulation code, sequences appearing in recording data are limited to 2T to 8T marks and spaces.

  In the embodiment described below, the length is divided into three types of 2T, 3T, and ≧ 4T, and the mark and space are paired to determine the recording compensation amount for each pattern.

  3 shows the contents of the pattern memory 212 (patterns 1, 2, and 3) used in the system (apparatus) of FIG. 1 and the contents of the distance difference memory 220/222 (for mark rear end control and mark front end control). It is a figure explaining an example of a relationship.

  For example, the first line on the right side of FIG. 3 shows a pattern for recording a 2T mark / 2T space. The result (MEC) calculated using the pattern in the first row is stored at an address corresponding to the location indicated by the arrow in the distance difference memory 220/222 for mark trailing edge control.

  Here, an example of how the patterns 2 and 3 are selected will be described. The pattern 2 has a condition that the location corresponding to the code bit string “10” (or “01”) appearing in the center of the pattern 1 is “00” (or “11”), and the modulation code (RLL (1, 7)). The pattern having the minimum Euclidean distance with respect to the ideal signal of pattern 1 (IEA in FIG. 4 to be described later) is used under the condition that the rule of the above is satisfied. In the pattern 3, the condition corresponding to the code bit string “10” (or “01”) appearing in the center of the pattern 1 is “11” (or “00”) and the modulation code (RLL (1,. 7) etc.) is used under the condition that the rule is satisfied, and the pattern having the minimum Euclidean distance with respect to the ideal signal of pattern 1 (IEA in FIG. 4) is adopted.

When two sequences having the same length are PA (n) and PB (n) (where n = 0 to N), the Euclidean distance is
Σ _{n = 0} ^N {PA (n) −PB (n)} ² (1)
Given in.

  Hereinafter, the Euclidean distance will be described with a specific example. In the second row of FIG. 3, “000111001111” is adopted as the pattern 1. On the other hand, “000110001111” is adopted as the pattern 2. The only difference between the patterns 1 and 2 is only whether the central bit is “10” or “00”.

  The ideal signal of pattern 1 (IEA in FIG. 4) is “000135532356531”, and the ideal signal of pattern 2 (IEB in FIG. 4) is “000134311356531”. The Euclidean distance between these two series is “10”. Here, only the above-mentioned “000110001111” has a pattern whose central bit is “00” and the Euclidean distance between the ideal signal and the ideal signal of pattern 1 is “10” or less. For this reason, “000110001111” is adopted as the pattern 2.

  If attention is paid to the pattern 3 in the second row in FIG. 3, “000111100111” is adopted. A pattern obtained by changing the central bit “10” of pattern 1 to “11” is “000111101111”. The Euclidean distance between the ideal signal “000135654456531” of the pattern “000111101111” and the ideal signal “000135532356531” of the pattern 1 is “10”, the center bit is “11”, and the ideal signal and the pattern 1 Only the pattern “000111101111” has the Euclidean distance from the ideal signal equal to or less than “10”. However, since the pattern “000111101111” includes the bit sequence “101” and violates the rule of the modulation code (RLL (1, 7)), “000111101111” is not adopted as the pattern 3. The pattern “000111100111” that satisfies the rule of the modulation code (RLL (1, 7)) is adopted as the pattern 3.

  The Euclidean distance between the ideal signal “000135653235531” of the pattern “000111100111” and the ideal signal “000135532356531” of the pattern 1 is “12”. The pattern of the modulation code (RLL (1, 7)) is satisfied, the central bit is a pattern of “11”, and the Euclidean distance between the ideal signal and the ideal signal of pattern 1 is “12” or less. Only “000111100111” above. For this reason, “000111100111” is adopted as the pattern 3.

  Next, the basic concept of the recording compensation amount calculation method according to the embodiment of the present invention will be described with reference to FIGS.

  FIG. 4 is a diagram for explaining the relationship between the reproduction signal (E200) and the ideal signals (IEA, IEB, IEC) of patterns 1 to 3 in the configuration of FIG. Now, consider a case where each of the patterns 1, 2, and 3 selected by the pattern discriminator 210 in FIG. 1 has contents as shown in the upper part of FIG. The ideal signals IEA, IEB, and IEC calculated from the patterns 1, 2, and 3 correspond to waveforms as shown in the lower part of FIG. Since the PR characteristic in this embodiment is PR (1, 2, 2, 1) with a constraint length of “4”, the ideal signals for the first 3 bits and the last 3 bits of patterns 1, 2, and 3 are Indeterminate.

The ideal signal sequences (IEA, IEB, IEC) of the patterns 1, 2, and 3 shown in FIG. 4 are P1 (t), P2 (t), and P3 (t), respectively, and the reproduction signal is Y (t). Then, Euclidean distances E1, E2, and E3 between P1 (t), P2 (t), P3 (t), and Y (t) are
E1 = Σ {Y (t) −P1 (t)} ² (2)
E2 = Σ {Y (t) −P2 (t)} ² (3)
E3 = Σ {Y (t) −P3 (t)} ² (4)
It becomes. The condition that the identification result of the reproduction signal becomes the pattern E2 even though the pattern 1 is recorded is as follows:
E1> E2 (5)
Similarly, the condition that the identification result of the reproduction signal becomes the pattern E3 even though the pattern 1 is recorded is as follows.
E1> E3 (6)
It is.

Here, the Euclidean distance difference (D2, D3) defined as follows:
D2 = E2-E1 (7)
D3 = E3-E1 (8)
think of.

  FIG. 5 is a diagram illustrating the distribution of the Euclidean distance difference (D2 = E2-E3, D3 = E3-E1) calculated in the configuration of FIG. In FIG. 5, a region where each distribution of the Euclidean distance differences D2 and D3 is 0 or less corresponds to an error.

Now, the average of the Euclidean distance differences D2 and D3 is M2 and M3, respectively, and the standard deviations of the distance differences D2 and D3 are σ2 and σ3, respectively. Then, when the pattern 1 is recorded, the margin Mgn2 for preventing the identification result of the reproduction signal from becoming the pattern 2 is
Mgn2 = M2 / σ2 (9)
It becomes.

Similarly, when the pattern 1 is recorded, the margin Mgn3 for the reproduction signal identification result not to be the pattern 3 is:
Mgn3 = M3 / σ3 (10)
It becomes.

  Here, when pattern 1 is recorded, an event in which the identification result of the reproduced signal is pattern 2 (an event that is mistakenly identified as pattern 2 when it should be identified as pattern 1) and an identification result of the reproduced signal are An event that becomes pattern 3 (an event that is mistaken for pattern 3 when it should be identified as pattern 1) is considered to be a conflicting event.

  FIG. 6 is a diagram illustrating the Euclidean distance correction amount based on the Euclidean distance difference (D2 = E2-E3, −D3 = E1-E3) calculated in the configuration of FIG.

FIG. 6 illustrates the distribution of the Euclidean distance differences D2 and -D3. A certain value Ec (recording compensation parameter described later) is set on the horizontal axis of FIG. The margins Mgn2 ′ and Mgn3 ′ of the distance difference distribution D2 and the distance difference distribution −D3 up to the set value Ec are:
Mgn2 ′ = (M2−Ec) / σ2 (11)
Mgn3 ′ = (M3 + Ec) / σ3 (12)
It becomes.

Solving for Ec as if equation (11) and equation (12) are equal (two margins Mgn2 ′ and Mgn3 ′ are equal):
Ec = (σ3 * M2 + σ2 * M3) / (σ2 + σ3)
... (13)
Is obtained.

  If the distribution of FIG. 6 (distance difference distribution D2 and distance difference distribution −D3) is shifted as a whole by Ec obtained by Expression (13) (in the example of FIG. 6, the origin “0” on the vertical axis is changed). If the recording compensation parameter Ec is shifted to the right to the set position), when the pattern 1 is recorded, the reproduction signal identification result becomes the pattern 2 and the reproduction signal identification result becomes the pattern 3 Will be equal. This state corresponds to the state where error is most difficult.

  In other words, the waveform compensation amount WC corresponding to the recording compensation parameter Ec is generated by the parameter calculation unit 224 in FIG. 1, and the generated compensation amount WC is given to the recording waveform creation unit 230 in FIG. By performing recording compensation such that the probability that the identification result is pattern 2 is sometimes equal to the probability that the identification result is pattern 3 is a state in which the probability of reading error of the reproduced signal with respect to the recorded information is the lowest. . As a result, for example, good recording / reproduction can be performed even on a high-density optical disk using a blue laser.

  The sign of the recording compensation parameter Ec corresponds to “whether the recording mark is made larger or smaller”, and the absolute value of Ec corresponds to “the change amount of the recording mark size”. Further, in the example of FIG. 6, the sign of the recording compensation parameter Ec indicates “whether the setting position of Ec is set on the right side or the left side of the origin“ 0 ””, and the absolute value of Ec is “Ec It shows how much the set position deviates from the origin “0”.

Here, the unit of the recording compensation parameter Ec is the Euclidean distance. In order to convert the Euclidean distance (Ec) into the amplitude (Vc) of the signal, the sequence length of the ideal signal is “7”.
Vc = √ (Ec / 7) (14)
And it is sufficient. Or, since the constraint length of the PR characteristic to be used is “4”,
Vc = √ (Ec / 4) (15)
And it is sufficient.

  In order to obtain the compensation amount WC of the recording pulse E230, it is necessary to obtain the time compensation amount from the amplitude compensation value Vc represented by the equation (14) or the equation (15), and further obtain the pulse compensation amount. However, since such two-stage conversion contents vary depending on the recording medium characteristics in addition to the mark length and space length, it is not easy to obtain a conversion formula for obtaining WC from Vc.

  However, it can be easily implemented if the recording compensation method is performed as follows from Ec in the equation (13) or Vc in the equation (14) or (15). That is, for example, in order to obtain the recording compensation amount from Ec, a dead zone is provided in the vicinity of the origin “0” in FIG. If Ec is within this dead zone, the next recording compensation amount WC is assumed to be unchanged. If Ec is larger than the dead zone, the next recording compensation amount is +1 step. Conversely, if Ec is smaller than the dead zone, the next recording compensation amount is set to −1 step. In accordance with the increase / decrease / no change [−1, 0, +1] of the recording compensation amount (WC) thus obtained, for example, by increasing / decreasing the width of the first pulse of the recording waveform E230 as illustrated in FIG. Compensation for the recording waveform E230 can be performed.

  The width (size) of the dead zone and the size of ± step (how much the WC is changed per step) may be determined by testing with an actual apparatus.

  The compensation method for the recording waveform E230 is not limited to increasing or decreasing the width of the first pulse of the recording waveform E230. There is also a method of increasing or decreasing the width of the first pulse, last pulse and / or cooling pulse.

  Further, the method of changing the recording waveform pulse E230 is not limited to the pulse width change as exemplified by the broken line in FIG. That is, it may be a pulse height change as illustrated by the broken line in FIG. 8C or a pulse phase change as illustrated by the broken line in FIG. Further, the pulse width change, the pulse height change, and / or the pulse phase change shown in FIGS. 8B to 8D may be used in appropriate combination.

  Thus, by changing the pulse width, pulse height, and / or pulse phase of the recording waveform E230 based on the waveform compensation amount WC, the “probability that the identification result becomes the pattern 2 when the pattern 1 is recorded” In this embodiment, the control so that the probability that the identification result is pattern 3 becomes equal is referred to as “adaptive control of the recording waveform”.

  In this way, recording / reproduction is performed using the recording waveform pulse E230 newly created by “adaptive control of recording waveform”, Ec is calculated by the above-described method along with the recording / reproduction, and the same procedure is repeated several times thereafter. . By repeating this operation, the recording waveform pulse E230 is optimized (for an individual recording / reproducing system and / or an individual optical disk), and good recording / reproducing can be performed.

  In the above example, the change amount of the recording waveform pulse E230 is set to three steps of [-1, 0, +1]. However, the section of Ec is divided more finely, for example, [-2, -1, 0, +1]. , +2] may be set to 5 steps.

  By the way, a method of determining the number of times of repeating the calculation of the recording waveform pulse E230 is conceivable. As another method, a method in which an evaluation index value (Mgn described below) indicating the signal quality of a reproduction signal satisfies a specified value is also conceivable.

As the evaluation index value indicating the signal quality of the reproduction signal, Expression (9) or Expression (10) can be used. Hereinafter, Formula (9) or Formula (10) will be generalized and described. A reproduction signal when recording certain data is Y (t), an ideal signal of the recorded data is p (t), and an ideal signal of any data other than the recorded data is p ′ (t). The Euclidean distance Eo between Y (t) and p (t) is
Eo = Σ {Y (t) −p (t)} ²
... (16)
Similarly, the Euclidean distance Ee between Y (t) and p ′ (t) is
Ee = Σ {Y (t) −p ′ (t)} ²
... (17)
It is. From Eo and Ee, Euclidean distance difference D = Ee−Eo (18)
Ask for. From the mean M of this Euclidean distance difference D and its standard deviation σ,
Mgn = M / σ (19)
Ask for. The previous recording waveform pulse E230 is repeatedly calculated until the evaluation index value Mgn shown in the equation (19) becomes equal to or greater than a certain value.

  In the first embodiment described with reference to FIG. 1 and others, the lengths of marks / spaces recorded on the optical disc 100 are divided into three types of 2T, 3T, and ≧ 4T. There may be more classifications. For example, the length of the mark / space may be divided into four types of 2T, 3T, 4T, and ≧ 5T.

  FIG. 9 exemplifies the correspondence between the patterns 1, 2, and 3 and the configuration of the distance difference memory 220/222 when the mark / space length is divided into four types of 2T, 3T, 4T, and ≧ 5T. ing. The recording waveform pulse E230 can be obtained by the same procedure as in the first embodiment described with reference to FIG. 1 and others except that the types of patterns are different (three types are increased to four types).

  According to the embodiment of the present invention, it is possible to perform recording and reproduction so that a better reproduction signal can be obtained than in the case where the reproduction signal E200 is matched with the ideal signal of the recording data RD.

  For example, in the fourth row of FIG. 3, the Euclidean distance between the ideal signals of Pattern 1 and Pattern 2 is “12”, and the Euclidean distance between the ideal signals of Pattern 1 and Pattern 3 is “10”. When recording is performed so as to coincide with the ideal signal of pattern 1, assuming that white noise is the dominant factor of reproduction signal deterioration, Mgn2> Mgn3 and Ec <0. That is, recording is performed so that the 2T mark becomes small.

  Even when the 2T mark becomes small, a read signal read error can be avoided by using a Viterbi decoder (240 in FIG. 15 described later). This is because the Viterbi decoder uses that 1T of the modulation code rule is not included, and corresponds to the fact that no error occurs even if the 2T signal is somewhat small.

  However, when the reproduced signal is shifted from the ideal signal, another inconvenience may occur. For example, when a timing generation circuit that extracts a clock from the timing at which the reproduction signal E200 passes through the center level is used, the accuracy of the clock may deteriorate in the first embodiment of FIG. In that case, the pattern of FIG. 10 may be used instead of the pattern of FIG. In the pattern of FIG. 10, the reproduction signal E200 approaches the ideal signal of pattern 1 by adopting 1T signals that are not actually output by the Viterbi decoder as patterns 2 and 3. Similarly, the pattern shown in FIG. 11 may be used instead of the pattern shown in FIG.

  FIG. 12 is a diagram illustrating an example of a recording compensation amount (WC) determination pattern when the pattern illustrated in FIG. 3 or FIG. 10 is used.

  As the recording compensation amount (WC) determining pattern (recording data RD), a method of adopting random data and extracting the pattern 1 from the random data can be considered. As another method, a pattern as shown in FIG. 12 can be adopted as a recording compensation amount (WC) determining pattern. The pattern of FIG. 12 is a pattern that includes all of the pattern 1 of FIG. Furthermore, the arrangement is devised, and the pattern for obtaining the recording compensation amount of the nT mark / mT mark comes after the pattern for obtaining the recording compensation amount of the nT mark / mT space. With this arrangement, the pattern of FIG. 12 has a DSV (Digital Sum Value) of 0 for each row.

  Similarly, as the recording compensation amount (WC) determining pattern for the pattern of FIG. 9, the pattern shown in FIG. 13 is conceivable. Further, the recording data (RD) for the patterns in FIGS. 10 and 11 is also provided in the same manner as in FIG.

  The patterns 1, 2, 3, or the recording compensation amount (WC) determining pattern may be stored in advance in the information recording system (apparatus) (210, 212, etc. in FIG. 1). On the other hand, these patterns may differ depending on individual media (optical disc 100) used for recording and reproduction. Considering this, patterns 1, 2, 3 and / or a recording compensation amount (WC) determination pattern are recorded in advance on a part of each medium, for example, the lead-in area 102 of the optical disc 100 shown in FIG. It is also possible to keep it.

  As described above, if pattern data and / or recording compensation amount data for optimum recording / reproduction is recorded in advance on each information recording medium (raw disc / blank disc capable of recording / reproduction), a system (recording) using the medium is recorded. Reproducing apparatus, etc.) can record and reproduce information with a recording waveform suitable for the medium quickly and accurately.

  Specific examples of the information recording medium (raw disc / blank disc that can be recorded / reproduced) include DVD-RAM, DVD-RW, and DVD-R. Further, the recording location of the pattern data and / or recording compensation amount data for optimum recording / reproduction need not be limited to the lead-in area 102 in FIG. Good.

  In general, the lead-in area 102 is suitable as a recording location of pattern data and / or recording compensation amount data for optimum recording / reproduction, but another location may be suitable depending on the situation. For example, consider a case where the medium is a DVD-R and data recording has been completed up to the middle of the data area 104 of the DVD-R. In this case, pattern data and / or recording compensation amount data for optimum recording / reproduction can be recorded using a small recording area X immediately after data recording is completed. When recording new data on the DVD-R, recording waveform compensation is performed using the recording contents (pattern data and / or recording compensation amount data) of area X, and the compensated recording waveform is used (area X). New data can be recorded in the unrecorded area of the DVD-R.

  For example, when the medium has a recording layer on both sides, the data recording start position is closer to the lead-out area 106 than the lead-in area 102 when the A-side recording is finished and the B-side recording is started. There is. In this case, the pattern data and / or the recording compensation amount data may be preferably recorded in the lead-out area 106 where the seek distance of the PUH 200 may be short (even in such a case, the pattern data and / or the recording compensation). It is not hindered that the amount data is recorded in the lead-in area 102).

  FIG. 15 is a diagram for explaining the configuration of an information recording / reproducing system (apparatus) (second embodiment) according to another embodiment of the present invention. The embodiment of FIG. 15 has a configuration in which a Viterbi decoder 240 is added to the embodiment of FIG. In other words, in the embodiment of FIG. 15, the identification result D240 from the Viterbi decoder 240 is used as the input of the pattern discriminator 210 instead of the recording data RD. When this Viterbi identification result D240 is used, the distribution of 0 or less in the distribution illustrated in FIG. 5 disappears, and a calculation error occurs when obtaining the recording waveform pulse E230. However, when it is difficult to adjust the phase of the recording data RD and the reproduction signal E200, it is an effective method to use the Viterbi decoder 240 as in the embodiment of FIG.

  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 at the stage of implementation.

For example, in the formulas 2 to 4, the Euclidean distance Ea is obtained by a calculation method of “Ea = Σ {Y (t) −Px (t)} ² ” (a cumulative value of magnitude is obtained by squaring). However, “Eb = Σ | Y (t) −Py (t) |” may be calculated as other information corresponding to this Ea (a cumulative value of the magnitude is obtained by taking an absolute value).

  In the above description of the embodiment, the PR (1, 2, 2, 1) characteristic is used. However, the present invention can be implemented using other PR characteristics. The present invention can also be implemented using a modulation code other than the RLL (1, 7) code.

  In addition, the embodiments may be implemented in appropriate combination as much as possible, and in that case, the effect of the combination can be obtained.

  Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of constituent elements disclosed in this application. For example, even if one or more constituent requirements are deleted from all the constituent requirements shown in the embodiment, when at least one of the effects of the present invention or the effects of implementing the present invention is obtained, The deleted configuration can be extracted as an invention.

<Summary of each embodiment>
(1) a first pattern including a code bit string “10” or “01”, a second pattern whose location corresponding to the code bit string “10” or “01” is “00”, and the code bit string “ A third pattern whose location corresponding to “10” or “01” is “11” is prepared as a target pattern, and the ease of error in the second pattern of the reproduction signal when the first pattern is recorded; Recording compensation is performed so that the error probability of the reproduction signal to the third pattern becomes equal.

(2) A distance difference D = Ee−Eo is obtained from the distance Eo between the reproduction signal and the first pattern and the distance Ee between the reproduction signal and the second or third pattern. Using the average M of D and its standard deviation σ, the quality of the reproduction signal is judged from the value represented by M / σ.

(3) A distance E1 between the reproduction signal and the first pattern, a distance E2 between the reproduction signal and the second pattern, and a distance E3 between the reproduction signal and the third pattern are obtained. Subsequently, D2 = E2-E1 and D3 = E3-E1 are obtained. When the average of D2 is M2, the standard deviation is σ2, the average of D3 is M3, and the standard deviation is σ3, Ec is obtained as Ec = (σ2 * M3 + σ3 * M2) / (σ2 + σ3). A recording waveform compensation amount is obtained from Ec.

  As described above, according to the embodiment of the present invention, the quality of the reproduction signal can be appropriately evaluated. Alternatively, an appropriate waveform correction amount can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS The figure explaining the structure of the information recording / reproducing system (1st Embodiment) which concerns on one embodiment of this invention. The figure explaining an example of a structure of the ideal signal calculator used with the system of FIG. The figure explaining an example of the relationship between the contents of the pattern memory (patterns 1, 2, and 3) used in the system of FIG. 1 and the contents of the distance difference memory (for mark rear end control and mark front end control). The figure explaining the relationship between the reproduction signal (E200) and the ideal signal (IEA, IEB, IEC) in the configuration of FIG. The figure which illustrates distribution of the Euclidean distance difference (D2 = E2-E3, D3 = E3-E1) calculated in the structure of FIG. The figure explaining the Euclidean distance correction amount based on the Euclidean distance difference (D2 = E2-E3, -D3 = E1-E3) calculated in the configuration of FIG. The figure explaining the specific example of the recording waveform pulse used with the system of FIG. The figure explaining an example of the recording waveform compensation method used with the system of FIG. The figure explaining the 2nd example of the relationship between the contents (pattern 1, 2, 3) of the pattern memory used in the system of FIG. 1, and the contents (for mark rear end control, for mark front end control) of the distance difference memory. The figure explaining the 3rd example of the relationship between the contents (pattern 1, 2, 3) of the pattern memory used in the system of FIG. 1, and the contents of the distance difference memory (for mark rear end control, for mark front end control). The figure explaining the 4th example of the relationship between the contents (pattern 1, 2, 3) of the pattern memory used with the system of FIG. 1, and the contents of the distance difference memory (for mark rear end control, for mark front end control). FIG. 11 is a diagram for explaining an example of a recording compensation amount determination pattern when the pattern illustrated in FIG. 3 or FIG. 10 is used. FIG. 12 is a diagram for explaining an example of a recording compensation amount determination pattern when the pattern illustrated in FIG. 9 or FIG. 11 is used. The figure explaining the structure of the optical disk (DVD-RAM, DVD-RW, DVD-R etc.) as a medium which performs information recording or information reproduction by this invention. The figure explaining the structure of the information recording / reproducing system (2nd Embodiment) which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Optical disk (DVD-RAM, DVD-RW, DVD-R etc.); 200 ... Optical head (PUH); 208 (208A-208C) ... Distance calculator; 210 ... Pattern discriminator; 212 ... Pattern memory; 214A to 214C) ... ideal signal calculator; 220, 222 ... distance difference memory; 224 ... parameter calculator; 230 ... recording waveform generator; 240 ... Viterbi decoder.

Claims (1)

A first pattern including a sign bit string "10" or "01", the code bit string "10" or the portion corresponding to "01" is "11" and the second pattern is, the code bit string "10" or "01" portion corresponding to "00" the third pattern and the pattern providing means and for providing a; and reproducing means for recording and reproducing the first pattern using Jo Tokoro information recording medium; before type recording and reproducing means according to the second identified as being reproduced signal of said first pattern corresponds to the first probability and / or a third pattern that is identified as corresponding to the second pattern from the probability, in the procedures utilized in the information recording and reproducing system that includes a compensation amount calculating means for calculating the recording compensation amount for the information recording medium,
A first error in which the reproduction signal obtained from the information recording medium is mistakenly recognized as corresponding to the second pattern when the first pattern is recorded on the information recording medium; When the first pattern is recorded on the medium, the reproduction signal obtained from the information recording medium is an event that is contradictory to the second ease of error that is mistakenly recognized as corresponding to the third pattern,
A first error in which the reproduction signal obtained from the information recording medium is mistakenly recognized as corresponding to the second pattern when the first pattern is recorded on the information recording medium; When the first pattern is recorded on the medium, the second error probability that the reproduced signal obtained from the information recording medium is mistakenly recognized as corresponding to the third pattern is substantially equal. And setting the recording compensation amount calculated by the compensation amount calculating means,
An information recording / reproducing method in which recording / reproduction is performed with the set recording compensation amount .

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