JP2012053967A - Optical disk device and jitter measuring method for optical disk device - Google Patents

Abstract

An optical disc apparatus capable of reducing jitter errors is provided.
An optical disk apparatus 200 according to the present invention is an optical disk apparatus that records information by irradiating a recording pulse light onto an optical disk 1 to form marks and spaces, and includes reproducing means 30 and 40, classification means 80, It has a measuring means 90 and recording pulse adjusting means 110, 120, 140. The reproduction means reproduces information recorded on the optical disc to generate a reproduction pulse signal. The classifying unit classifies a plurality of marks or spaces included in the reproduction pulse signal with a clock cycle as a reference unit. The jitter measuring means measures the jitter or deviation of the presence distribution for each classified mark or space. The recording pulse adjusting means increases the overlap between the existence distribution of the first classification and the existence distribution of the second classification, while the existence distribution of the first and second classifications and the existence distribution of the third classification The recording pulses for the first classification are adjusted so as to reduce the overlap of the first classification.
[Selection] Figure 1

Description

  The present invention relates to an optical disc apparatus and a jitter measurement method for the optical disc apparatus.

  In recent years, as the recording density of optical discs has increased dramatically, it is desired to record information on optical discs with higher accuracy. On the other hand, a wide variety of optical discs are supplied from optical disc manufacturers. In order to record information on each optical disc with high accuracy, the modulation waveform of the drive current of the laser that emits the recording pulse light is changed to that of the optical disc. It is necessary to operate according to the type. This operation is usually called a write strategy, and is executed by adjusting various recording control parameters according to the type of the optical disc. In addition, development of a technique for automatically changing a write strategy in accordance with a change in characteristics of an optical disk at the time of recording, such as thermal interference that occurs when a mark or space is formed by irradiating a laser on an optical disk, is also progressing. In the technique of automatically changing the write strategy, recording control parameters are adjusted based on jitter and deviation measured by statistically processing temporal fluctuations of a reproduced pulse. For example, the following Patent Document 1 and Patent Document 2 disclose techniques for adjusting recording control parameters based on measured jitter.

JP 2005-158159 A JP 2009-87484 A

  Normally, when information is recorded on an optical disc, the write strategy is adjusted so that marks and spaces of a specified length are recorded. However, the mark length (mark length) or space length (space length) actually recorded on the surface of the optical disc by laser irradiation may be deviated from the specified length due to the effect of changes in the characteristics of the optical disc. is there. In particular, when the deviation from the specified length is large, the reproduced pulses interfere with each other, and there is a problem that jitter and deviation errors increase. As a result, the accuracy of the write strategy adjusted based on jitter and deviation does not improve.

  The present invention has been made to solve the above-described problems. Accordingly, an object of the present invention is to provide an optical disc apparatus capable of reducing jitter and deviation errors.

  Another object of the present invention is to provide a jitter measuring method for an optical disc apparatus capable of reducing jitter and deviation errors.

  The above object of the present invention is achieved by the following means.

  An optical disk apparatus according to the present invention is an optical disk apparatus for recording information by irradiating a recording pulse light onto an optical disk to form marks and spaces, and has a reproducing means, a classification means, a measuring means, and a recording pulse adjusting means. . The reproduction means reproduces information recorded on the optical disc to generate a reproduction pulse signal. The classifying unit classifies a plurality of marks or spaces included in the reproduction pulse signal with a clock cycle as a reference unit. The jitter measuring means measures the jitter or deviation of the presence distribution for each classified mark or space. The recording pulse adjusting means increases the overlap between the existence distribution of the first classification and the existence distribution of the second classification, while the existence distribution of the first and second classifications and the existence distribution of the third classification The recording pulses for the first classification are adjusted so as to reduce the overlap of the first classification.

  A jitter measuring method for an optical disc device according to the present invention is a jitter measuring method for an optical disc device for recording information by irradiating a recording pulse light onto an optical disc to form a mark and a space, and recorded on the optical disc. Reproducing information to generate a regenerative pulse signal, classifying a plurality of marks or spaces included in the regenerative pulse signal with a clock period as a reference unit, and jitter or deviation of existence distribution for each classified mark or space , And the overlap between the distribution of the first classification and the distribution of the second classification is increased while the distribution of the distribution of the first and second classifications and the distribution of the third classification exists. The recording pulses for the first classification are adjusted so as to reduce the.

  According to the optical disc device and the jitter measuring method for the optical disc device of the present invention, pulses having different lengths are prevented from interfering with each other, so that jitter and deviation errors are reduced.

1 is a block diagram of an optical disc device according to a first embodiment of the present invention. It is a flowchart of the write strategy preparation process in the 1st Embodiment of this invention. It is a figure for demonstrating a jitter. It is a flowchart of the jitter measurement process classified by classification shown in FIG. FIG. 5 is a diagram showing a presence distribution after adjusting a pulse length in the jitter measurement processing classified by classification shown in FIG. 4. FIG. 5 is a diagram for explaining adjustment of a pulse length in the classification-specific jitter measurement processing shown in FIG. 4. It is a flowchart of the jitter measurement process classified by classification in the 2nd Embodiment of this invention. 8A is a diagram for explaining the existence distribution after the even-numbered pulse length is adjusted in the jitter measurement processing classified by classification shown in FIG. 7, and FIG. 8B is a diagram for adjusting the odd-numbered pulse length. It is a figure for demonstrating existence distribution after having performed. It is a flowchart of the jitter measurement process classified by classification in the 3rd Embodiment of this invention. FIG. 10A is a diagram for explaining the existence distribution after adjusting the even-numbered pulse length in the jitter measurement processing classified by classification shown in FIG. 9, and FIG. 10B adjusts the odd-numbered pulse length. It is a figure for demonstrating existence distribution after having performed. FIG. 11A is a diagram showing the measurement target pulse, and FIGS. 11B to 11E illustrate that the mark length or space length of other pulses changes to cause interference with the measurement target pulse. It is a figure for doing. It is a figure for demonstrating the jitter measurement process classified by classification in the 4th Embodiment of this invention.

  Embodiments of an optical disc apparatus and a jitter measuring method for the optical disc apparatus according to the present invention will be described below with reference to the accompanying drawings. In the following embodiments, a DVD + R will be described as an example of an optical disk.

(First embodiment)
FIG. 1 is a block diagram of an optical disc apparatus according to the first embodiment of the present invention. The optical disk apparatus according to the present embodiment reduces jitter and deviation errors due to interference between pulses while maintaining the optical disk surface in a state close to thermal distribution characteristics during actual data recording. As shown in FIG. 1, the optical disc apparatus 200 of this embodiment includes an optical pickup 10, a spindle motor 20, a head amplifier 30, a binarization circuit 40, a decoder 50, a mark edge detector 60, a RAM 70, a data classification discriminator ( Classification means) 80, jitter measurement section (jitter measurement means) 90, encoder 100, write strategy calculation section 110, recording pulse adjustment section 120, laser drive section 130, and control section 140. The head amplifier 30 and the binarization circuit 40 function as reproduction means, and the write strategy calculation unit 110, the recording pulse adjustment unit 120, and the control unit 140 function as recording pulse adjustment means.

  The control unit 140 controls the recording operation and the reproduction operation of the optical disc apparatus 200. Specifically, the control unit 140 controls the optical pickup 10, the spindle motor 20, the head amplifier 30, the binarization circuit 40, and the decoder 50 to generate a reproduction signal from information read from the optical disc. In addition, the control unit 140 controls the encoder 100, the write strategy calculation unit 110, the recording pulse adjustment unit 120, and the laser driving unit 130 to record a recording signal on the optical disc.

  Further, the control unit 140 controls the mark edge detection unit 60, the RAM 70, the data classification discrimination unit 80, the jitter measurement unit 90, and the write strategy calculation unit 110 to execute a write strategy preparation process. In the write strategy preparation process, after recording and reproducing with a default write strategy, a classification-specific jitter measurement process is executed as necessary. The write strategy preparation process and the classified jitter measurement process will be described later.

  Hereinafter, main configurations of the reproduction signal processing system and the recording signal processing system of the optical disc apparatus 200 will be described in order. Note that other components of the optical disk apparatus according to the present embodiment are the same as those of the conventional optical disk apparatus, and thus description thereof is omitted.

  The optical pickup 10 is for irradiating the optical disc 1 with pulsed light and receiving reflected light from the optical disc 1. More specifically, the optical pickup 10 has a laser light source and a light receiving unit, irradiates the optical disk 1 rotated by the spindle motor 20 with laser pulse light, and reflects reflected light reflected by the recording surface of the optical disk 1. Receive light. A light emitting element such as a laser diode is used as the laser light source. The light receiving unit includes a plurality of light receiving elements that receive the laser light reflected by the recording surface of the optical disc 1 and convert it into an electrical signal.

  The optical disc 1 has a recording area for writing recording information, an inner test area arranged along the inner circumference, and an outer test area arranged along the outer circumference. In addition, the optical disc 1 is prerecorded with unique information such as the optical disc manufacturer and model number.

  Examples of the optical disk include CD-R, CD-RW, DVD ± R, DVD-RW, DVD-RAM, and Blu-ray. In the present embodiment, the case of a DVD + R disc as an optical disc will be described as an example. As the recording material for the optical disc 1, in the case of DVD + R, for example, an organic dye material such as cyanine or azo is used.

  The head amplifier 30 generates an RF signal from the recording information of the optical disc 1 read by the optical pickup 10. More specifically, the head amplifier 30 calculates and amplifies a signal from the light receiving unit of the optical pickup 10, and generates an RF signal from the read recording information of the optical disc 1.

  The binarization circuit 40 converts the RF signal generated by the head amplifier 30 into a high or low binary reproduction pulse signal.

  The decoder 50 decodes the reproduction pulse signal generated by the binarization circuit 40 and outputs it as a reproduction signal. Further, the decoder 50 extracts a clock signal from the reproduction signal.

  As described above, in the reproduction signal processing system of the optical disc apparatus 200, the laser light emitted from the optical pickup 10 is reflected by the recording surface of the optical disc 1, and the reflected light is captured by the light receiving unit built in the optical pickup 10. It is converted into an electrical signal. The electric signal output from the light receiving unit is calculated and amplified by the head amplifier 30 and then transmitted to the binarization circuit and output as a reproduction signal via the decoder 50.

  The mark edge detector 60 detects the mark edge of the reproduction pulse signal. More specifically, the mark edge detection unit 60 detects a mark edge (an edge that changes from a mark to a space, or an edge that changes from a space to a mark) of the reproduction pulse signal generated by the binarization circuit 40, Play marks and spaces. The reproduced mark and space data is transmitted to the RAM 70. Further, the mark edge detection unit 60 calculates a mark edge deviation, which is a deviation of the mark edge from the clock, based on the reproduction pulse signal and the clock extracted by the decoder 50. Mark edge deviation data is also transmitted to the RAM 70. In the following description, the reproduced mark or space is simply referred to as a pulse, and the mark length or space length is referred to as a pulse length.

  The RAM 70 stores reproduction pulse data. More specifically, the RAM 70 stores mark and space data reproduced by the mark edge detection unit 60 and mark edge deviation data.

  The data classification discriminating unit 80 classifies or discriminates the reproduction pulse data. More specifically, the data classification discriminating unit 80 generates a presence distribution by classifying marks or spaces stored in the RAM 70 with respect to specific items using a clock cycle as a reference unit. For example, the data classification discriminating unit 80 classifies a plurality of marks stored in the RAM 70 according to the mark length with the clock cycle as a reference unit, and generates the presence distribution of the marks. Further, the data classification discriminating unit 80 classifies the plurality of spaces stored in the RAM 70 by the space length using the clock cycle as a reference unit, and generates a space presence distribution.

  Further, the data classification discriminating unit 80 transmits the reproduction pulse data stored in the RAM 70 to the write strategy calculation unit 110 as necessary. For example, the data classification discriminating unit 80 transmits the mark edge deviation data stored in the RAM 70 to the write strategy calculation unit 110.

  The jitter measuring unit 90 measures the jitter or deviation of the existence distribution generated by the data classification discriminating unit 80. More specifically, the jitter or deviation of the existence distribution relating to each mark or space classified by the data classification discriminator 80 is measured. In the present embodiment, the jitter measuring unit 90 measures the jitter value based on the standard deviation of the mark or space presence distribution. The deviation corresponds to the average value of the existence distribution.

  The encoder 100 converts the input recording signal into a predetermined encoded signal. More specifically, the encoder 100 encodes the recording signal by 8/16 modulation, for example.

  The write strategy calculation unit 110 calculates a write strategy. More specifically, the write strategy computing unit 110 computes a write strategy based on the jitter or deviation measured by the jitter measuring unit 90, the mark edge deviation data discriminated by the data classification discriminating unit 80, and the like. The write strategy calculation unit 110 optimizes the rise and fall timing of the recording pulse waveform and the laser irradiation power of the recording pulse under specific recording conditions of the optical disc.

  Further, the write strategy calculation unit 110 also has a function of freely setting the rising and falling timings of the recording pulse with a predetermined resolution within a range of, for example, 3T to 14T (T is a clock cycle). Therefore, the recording pulse can be freely adjusted for a specific pulse length of the optical disc format.

  Furthermore, the write strategy calculation unit 110 includes a ROM for storing a default write strategy and a RAM for temporarily storing the write strategy obtained by the calculation. The ROM stores a default write strategy corresponding to the type of the optical disc 1. For example, when information is recorded on a CAV recording type optical disk, the recording speed differs between the inside and the outside of the optical disk. The write strategy calculation unit 110 holds information defining how to change the write strategy according to the recording speed in the ROM, and changes the write strategy as appropriate according to the recording speed. The RAM stores recording control parameters relating to the rise and fall timings of the recording pulse waveform obtained by the calculation.

  The recording pulse adjustment unit 120 generates a recording pulse. More specifically, the recording pulse adjustment unit 120 generates a recording pulse based on the signal encoded by the encoder 110 and the write strategy defined by the write strategy calculation unit 110.

  The laser driving unit 130 drives the laser of the optical pickup 10. More specifically, the laser driving unit 130 drives the laser diode by supplying the recording pulse generated by the recording pulse adjusting unit 120 to the laser diode of the optical pickup 10.

  As described above, in the recording signal processing system of the optical disc apparatus 200, the recording signal input to the encoder 110 is encoded and then input to the recording pulse adjustment unit 120. The recording pulse adjustment unit 120 generates a recording pulse based on the write strategy defined by the write strategy calculation unit 110. The generated recording pulse is supplied to the laser driving unit 130, and information is recorded on the recording surface of the optical disc 1 by the irradiated recording pulse light.

  Next, a jitter measurement method for the optical disk device according to the present embodiment will be described. FIG. 2 is a flowchart of the write strategy preparation process of the present embodiment. The write strategy preparation process is a preliminary process before the general write strategy adjustment process, and the general write strategy adjustment process is executed after the write strategy preparation process. In the present embodiment, description of general write strategy adjustment processing is omitted. As will be described below, in the write strategy preparation process, jitter or deviation is measured after recording and reproduction with a default write strategy, and a classification-specific jitter measurement process is executed as necessary.

  As shown in FIG. 2, first, the write strategy is set to default (step S101). More specifically, the write strategy calculation unit 110 sets default recording control parameters stored in the ROM according to the type of the optical disc 1.

  Next, test data is recorded on the optical disc 1 (step S102). More specifically, test data is recorded on the optical disc 1 by a write strategy using the recording control parameters set in step S101.

  Next, the optical disk 1 is reproduced (step S103). More specifically, a reproduction pulse signal is generated by reproducing the optical disk 1 on which test data is recorded. Then, the mark edge included in the reproduction pulse signal is detected by the mark edge detection unit 60, the mark and space are reproduced, and stored in the RAM 70 as reproduction pulse data.

  Next, the pulses are classified (step S104). More specifically, for example, the marks stored in the RAM 70 are classified with respect to the mark length using the clock cycle as a reference unit to generate the presence distribution of the marks.

  Next, jitter is measured (step S105). More specifically, the jitter value of the presence distribution generated in step S104 is calculated. Hereinafter, the jitter will be described in more detail with reference to FIG.

  FIG. 3 is a diagram for explaining jitter. In FIG. 3, the horizontal axis represents the mark length of the reproduced mark, and the vertical axis represents the frequency at which the mark length appears. The solid line is a curve indicating the presence distribution obtained by measurement, and the broken line is a virtual curve indicating the contribution of each mark length to the presence distribution.

  As described above, in the present embodiment, the jitter is obtained based on the standard deviation of the distribution of the mark or space. As shown in FIG. 3, the jitter obtained by the measurement is a wave-like curve as a whole indicated by a solid line. On the other hand, the existence distribution of each mark indicated by a broken line has a portion where adjacent marks overlap each other due to mutual interference such as 3T and 4T pulses, and the marks included in this portion are recorded. Sometimes it is impossible to distinguish which mark was recorded. Therefore, the jitter as shown in FIG. 3 in which mutual interference occurs between the marks includes an error. Hereinafter, the write strategy preparation process will be described with reference to FIG. 2 again.

  Next, the magnitude relationship between the jitter and the predetermined value is determined (step S106). If the jitter is smaller than the predetermined value (step S106: YES), the process is terminated.

  On the other hand, when the jitter is equal to or greater than the predetermined value (step S106: NO), the classification-specific jitter measurement process (step S107) is executed, and then the process ends. The classification jitter measurement process will be described below.

  4 is a flowchart of classification-specific jitter measurement processing according to the present embodiment, FIG. 5 is a diagram showing an existence distribution after adjusting the pulse length, and FIG. 6 is a diagram for explaining adjustment of the pulse length. It is. In the jitter measurement processing classified by classification according to this embodiment, 3T to 8T pulses are divided into three groups, and jitter or deviation is measured for each group. In the following description, only the 3T to 8T pulses will be described for convenience, but the 9T and subsequent pulses can be processed in the same manner.

  As shown in FIG. 4, first, jitter or deviation is measured for 3T and 6T pulses (step S201). In order to prevent the presence distribution of adjacent pulses from interfering with each other, for example, 4T, 5T, 7T, and 8T pulses may be moved as shown in FIG. That is, while increasing the overlap between the presence distribution of the 4T pulse (first classification) and the presence distribution of the 5T pulse (second classification), the 4T pulse (first classification) and the 5T pulse (second classification) are increased. ) And the pulse length of the recording pulse are adjusted so as to reduce the overlap between the presence distribution of 3T pulses (third classification).

More specifically, as shown in FIG. 6, the 4T pulse is expanded and set to (4 + 2ΔT ₄ ) T, and 5T is reduced and set to (5-2ΔT ₅ ) T. Further, the 7T pulse is expanded and set to (7 + 2ΔT ₇ ) T, and the 8T pulse is reduced and set to (8−2ΔT ₈ ) T. Here, ΔT _{4 to} ΔT ₈ can be set in a range of 0.05 to 0.2, for example. Although FIG. 6 shows an example in which the mark is enlarged or reduced, the space can be similarly enlarged or reduced.

  By setting in this way, as shown in FIG. 5, the overlap between the 4T pulse existence distribution and the 5T pulse existence distribution increases, while the 3T pulse and 6T pulse existence distributions and the existence distributions of other pulse lengths. The overlap with is reduced. By setting each pulse length as described above and measuring jitter or deviation for 3T pulse and 6T pulse, it is possible to prevent pulses having different lengths from interfering with each other, thereby reducing jitter and deviation errors. . In addition, since the existence distribution of the 4T pulse and the 5T pulse still exists between the 3T pulse and the 6T pulse, it is possible to prevent the thermal distribution characteristic of the optical disc surface from changing significantly before the movement.

Next, jitter or deviation is measured for 4T and 7T pulses (step S202). The 3T pulse is reduced to (3-2ΔT ₃ ) T, and the 5T pulse is expanded to (5 + 2ΔT ₅ ) T. Further, the 6T pulse is reduced and set to (6-2ΔT ₆ ) T, and the 8T pulse is expanded and set to (8 + 2ΔT ₈ ) T. Here, ΔT _{3 to} ΔT ₈ can be set in a range of 0.05 to 0.2, for example. By setting in this way, the overlap between the presence distribution of the 5T pulse and the presence distribution of the 6T pulse increases, while the overlap between the presence distribution of the 4T pulse and the 7T pulse and the presence distribution of other pulses decreases. By setting each pulse length as described above and measuring jitter or deviation for the 4T pulse and 7T pulse, it is possible to prevent pulses having different lengths from interfering with each other, thereby reducing jitter and deviation errors. . In addition, since the existence distribution of the 5T pulse and the 6T pulse still exists between the 4T pulse and the 7T pulse, it is possible to prevent the thermal distribution characteristic of the optical disc surface from changing significantly before the movement.

Next, jitter or deviation is measured for 5T and 8T pulse lengths (step S203). The 4T pulse is reduced to (4-2ΔT ₄ ) T, the 6T pulse is extended to (6 + 2ΔT ₆ ) T, and the 7T pulse is reduced to (7-2ΔT ₇ ) T. Here, ΔT _{4 to} ΔT ₇ can be set in a range of 0.05 to 0.2, for example. By setting in this way, the overlap between the 3T pulse existence distribution and the 4T pulse existence distribution increases, while the overlap between the 5T pulse and 8T pulse existence distributions and other pulse length distributions decreases. By setting each mark length as described above and measuring jitter or deviation for the 5T pulse and 8T pulse, it is possible to prevent pulses having different lengths from interfering with each other, thereby reducing jitter and deviation errors. . In addition, since the 6T pulse and 7T pulse existence distributions still exist between the 5T pulse and the 8T pulse, it is possible to prevent the thermal distribution characteristics of the optical disc surface from changing significantly before the movement.

  As described above, in this embodiment, when the pulse lengths (classifications) of a plurality of pulses (marks or spaces) are arranged in ascending order with respect to the clock cycle length, n + 1 and n + 2th pulse lengths (classifications) are assumed to be natural numbers. N + 1 and n + 2 so as to reduce the overlap between the distribution of the nth and n + 3th pulse length (classification) and the distribution of other pulse lengths (classification). Adjust the recording pulse for the second pulse length (classification).

In the above, an example in which the rising edge and the falling edge of the pulse are expanded or contracted by the same adjustment amount (ΔT _{3 to} ΔT ₈ ) has been shown. However, the adjustment amount may be different between the rising edge and the falling edge.

  As described above, the described embodiment has the following effects.

  (A) According to the optical disk device and the jitter measurement method for the optical disk device of the present embodiment, pulses having different lengths are prevented from interfering with each other, so that jitter and deviation errors due to interference can be reduced. Can do.

  (B) According to the optical disk apparatus and the jitter measurement method for the optical disk apparatus of the present embodiment, the jitter and deviation due to interference are maintained while maintaining the optical disk surface in a state close to the thermal distribution characteristic during actual data recording. The error can be reduced.

(Second Embodiment)
In the first embodiment, 3T to 8T pulses are divided into three groups, and jitter or deviation is measured for each group. In this embodiment, 3T-8T pulses are divided into odd and even pulse lengths to measure jitter or deviation. Since this embodiment is the same as the first embodiment except that the pulse length is divided into odd and even numbers and jitter or deviation is measured, description of other configurations is omitted.

  FIG. 7 is a flowchart of the classification-specific jitter measurement processing of the present embodiment, and FIG. 8A is a diagram for explaining the existence distribution after adjusting the even-numbered pulse length, and FIG. () Is a diagram for explaining the existence distribution after adjusting the odd-numbered pulse length.

  As shown in FIG. 7, first, jitter or deviation is measured by superimposing the even-numbered pulse length existence distribution on the odd-numbered pulse length existence distribution (step S301). More specifically, as shown in FIG. 8A, the even-numbered pulse length is reduced by reducing the even-numbered pulse length by 1T and adjusting the recording pulse so as to be equal to the odd-numbered pulse length. The existence distribution of (classification) is superimposed on the existence distribution of odd-numbered pulse lengths (classification). By setting each pulse length as described above and measuring jitter or deviation for the existence distribution of odd-numbered pulses, pulses of different lengths are prevented from interfering with each other, so jitter and deviation errors are reduced. Reduce.

  Next, jitter or deviation is measured by superimposing the existence distribution of the odd-numbered pulse length on the existence distribution of the even-numbered pulse length (step S302). More specifically, as shown in FIG. 8B, the odd-numbered pulse length is adjusted by expanding the odd-numbered pulse length by 1T and adjusting the recording pulse to be equal to the even-numbered pulse length. The existence distribution of (classification) is superimposed on the existence distribution of even-numbered pulse lengths (classification). By setting each pulse length as described above and measuring jitter or deviation for the even number pulse length distribution, it is possible to prevent pulses of different lengths from interfering with each other. Is reduced.

  As described above, the described embodiment has the following effects in addition to the effects of the first embodiment.

  (C) According to the optical disk device and the jitter measurement method for the optical disk device of the present embodiment, jitter or deviation is measured separately for odd and even pulse lengths, so the time required for jitter measurement processing is shortened. be able to.

(Third embodiment)
In the second embodiment, jitter or deviation is measured separately for odd-numbered and even-numbered pulse lengths. In the present embodiment, jitter or deviation is measured by superimposing one of the odd and even pulse lengths on a 1T pulse that does not exist as an optical disc format. The present embodiment is the same as the second embodiment except that either one of the odd-numbered pulse length and the even-numbered pulse length is superimposed on the 1T pulse to measure jitter or deviation. A description of the configuration is omitted.

  FIG. 9 is a flowchart of the classification-specific jitter measurement processing of the present embodiment, and FIG. 10A is a diagram for explaining the existence distribution after adjusting the even-numbered pulse length, and FIG. ) Is a diagram for explaining the existence distribution after adjusting the odd-numbered pulse length.

  As shown in FIG. 9, first, the presence distribution of the even-numbered pulse length is overlapped with the presence distribution of the 1T pulse, and the jitter or deviation of the presence distribution of the odd-numbered pulse length is measured (step S401). More specifically, as shown in FIG. 10A, the even-numbered pulse length (classification) is present by adjusting the recording pulse so that the even-numbered pulse length is reduced to be equal to the 1T pulse. The distribution is superimposed on the 1T pulse presence distribution. By setting each mark length as described above and measuring jitter or deviation for odd-numbered pulse lengths, it is possible to prevent pulses of different lengths from interfering with each other, thereby reducing jitter and deviation errors. .

  Next, the presence distribution of the odd-numbered pulse length is superimposed on the presence distribution of the 1T pulse, and the jitter or deviation of the even-numbered pulse length distribution is measured (step S402). More specifically, as shown in FIG. 10B, the odd-numbered pulse length (classification) is present by adjusting the recording pulse so that the odd-numbered pulse length is reduced to be equal to the 1T pulse. The distribution is superimposed on the 1T pulse presence distribution. By setting each mark length as described above and measuring jitter or deviation for even-numbered pulse lengths, it is possible to prevent pulses of different lengths from interfering with each other, thus reducing jitter and deviation errors. .

  In the present embodiment, 1T is exemplified as the pulse length that does not have the format of the optical disc. However, the pulse length may be smaller than 1T.

  As described above, the described embodiment has the following effects in addition to the effects of the first and second embodiments.

  (D) According to the optical disk apparatus and the jitter measurement method for the optical disk apparatus according to the present embodiment, one of the odd-numbered and even-numbered pulse lengths is superimposed on the 1T pulse that does not exist as an optical disk format. It is possible to reliably prevent interference between the pulses.

(Fourth embodiment)
In the first to third embodiments, the pulse length is adjusted by classifying the existence distribution relating to the pulse by the pulse length. Since the pulse length is the length between mark edges, adjusting the pulse length is replaced by adjusting the mark edge position. In the present embodiment, the presence distribution relating to the mark edge position is classified by the mark length and the space length, and the jitter or deviation is measured by adjusting the mark edge position. Since this embodiment is the same as the first to third embodiments except for the above-described difference in configuration, description of other configurations is omitted.

  FIG. 11 is a diagram for explaining interference between pulses due to a change in the mark edge position. FIG. 11A is a diagram showing a measurement target pulse, and FIGS. 11A to 11E show that the mark length or space length of other pulses changes to cause interference with the measurement target pulse. It is a figure for demonstrating.

  In FIG. 11 (A), the mark length and the space length before and after the trailing edge (falling edge) of the mark edge are mT and nT, respectively. The mark length and space length of the other pulses are (m + 1) T and nT, respectively. Here, as shown by a broken line, when the mark length of the trailing edge is shortened for some reason and the mark length approaches mT, the pulse waveform shown in FIG. 11B is changed to the pulse waveform shown in FIG. Interference between pulses occurs as they approach.

  In FIG. 11C, the mark length and space length of the other pulses are (m−1) T and nT, respectively. Here, as shown by the broken line, when the mark length of the trailing edge is increased for some reason and the mark length approaches mT, the pulse waveform shown in FIG. 11C approaches the pulse waveform shown in FIG. As a result, interference occurs between pulses.

  In FIG. 11D, the mark length and space length of other pulses are mT and (n + 1) T, respectively. Here, as shown by the broken line, when the space length of the trailing edge is shortened for some reason and the space length approaches nT, the pulse waveform shown in FIG. 11D approaches the pulse waveform shown in FIG. Therefore, interference between pulses occurs.

  Furthermore, in FIG. 11E, the mark length and space length of the other pulses are mT and (n−1) T, respectively. Here, as shown by a broken line, when the space length of the trailing edge becomes longer for some reason and the space length approaches nT, the pulse waveform shown in FIG. 11 (E) approaches the pulse waveform shown in FIG. 11 (A). Therefore, interference between pulses occurs.

  Therefore, in order to prevent other pulses from interfering with the pulses shown in FIG. 11A, even if the mark length or space length of the other pulses changes, at least FIGS. It is necessary to maintain the solid pulse waveform of (E).

  Therefore, assuming that the mark length or the space length changes by 1T at the maximum, the mark edge position of another pulse is adjusted in advance in the opposite direction by at least 1T with respect to the changing direction that interferes with the measurement target pulse, whereby the pulse Interference between each other can be prevented.

  That is, in the case of the pulse shown in FIG. 11B, interference with the pulse shown in FIG. 11A can be prevented by increasing the leading edge (rising edge) and setting the mark length to (m + 2) T or more. Can do. In the case of the pulse shown in FIG. 11C, interference with the pulse shown in FIG. 11A can be prevented by delaying the leading edge and setting the mark length to (m−2) T or less. . Similarly, in the case of the pulse shown in FIG. 11D, interference with the pulse shown in FIG. 11A can be prevented by delaying the leading edge of the subsequent pulse and setting the space length to (n + 2) T or more. be able to. Further, in the case of the pulse shown in FIG. 11 (E), interference with the pulse shown in FIG. 11 (A) can be prevented by shortening the leading edge of the next pulse and setting the space length to (n−2) T or less. can do.

  FIG. 12 is a diagram for explaining the classification-specific jitter measurement processing in the present embodiment. As shown in FIG. 12, each column of the matrix has a pulse mark length, and each row has a space length. In addition, in a grid where a column with a specific mark length and a row with a specific space length intersect, the moving direction of the leading edge in the combination of the mark length and the space length is indicated by “+” or “−”. Yes. “+” Indicates that the leading edge is moved in the right direction (a direction that is late in time), and “−” indicates that the leading edge is moved in the left direction (a direction that is earlier in time). For example, when the mark length is (m + 1) T and the space length is (n-1) T, the leading edge of the subsequent pulse is moved in the left direction (direction to advance in time). Note that the combination of the mark length and the space length with the blank movement direction indicates that it is not necessary to move the leading edge.

  As described above, in the present embodiment, the presence distribution of the mark edge position (first classification) of the pulse that may interfere with the measurement target pulse and the mark edge position (second classification) of the pulse other than the measurement target pulse. Increase overlap with presence distribution. On the other hand, the mark edge for the first classification is reduced so as to reduce the overlap between the existence distribution of the first and second classifications and the existence distribution of the mark edge position (third classification) of the measurement target pulse. Adjust the position. Specifically, the existence distribution related to the mark edge position is classified by the mark length and the space length, and the mark edge position is adjusted in the opposite direction to the change direction that interferes with the measurement target pulse.

  As described above, the present embodiment described above has the following effects in addition to the effects of the first to third embodiments.

  (E) According to the optical disk device and the jitter measurement method for the optical disk device of the present embodiment, the interference between the measurement target pulse and other pulses is prevented by adjusting the mark edge position. Can reduce jitter and deviation errors.

  As described above, in the first to fourth embodiments, the optical disk apparatus and the jitter measurement method for the optical disk apparatus of the present invention have been described. However, it goes without saying that the present invention can be appropriately added, modified, and omitted by those skilled in the art within the scope of the technical idea.

  For example, in the first to third embodiments, 3T to 8T pulses are divided into two or three groups, and jitter or deviation is measured for each group. However, the number of groups and how to divide groups are not limited to the above case.

  In the first to third embodiments, jitter or deviation was measured in order for all of the two or three groups. However, it is not always necessary to measure all groups, and measurement of any group can be omitted. Moreover, the order which measures about each group is not limited to the above-mentioned case.

1 optical disc,
10 Optical pickup,
20 spindle motor,
30 head amplifier,
40 Binarization circuit,
50 decoder,
60 Mark edge detector,
70 RAM,
80 Data classification discriminator,
90 Jitter measurement unit,
100 encoder,
110 Write strategy calculation unit,
120 recording pulse adjustment unit,
130 laser drive unit,
140 controller,
200 Optical disk device.

Claims (12)

An optical disc apparatus for recording information by irradiating a recording pulse light on an optical disc to form marks and spaces,
Reproducing means for reproducing information recorded on the optical disc to generate a reproduction pulse signal;
Classification means for classifying a plurality of marks or spaces included in the reproduction pulse signal with a clock cycle as a reference unit;
A jitter measuring means for measuring the presence distribution jitter or deviation for each classified mark or space;
To increase the overlap between the first distribution and the second distribution, while decreasing the overlap between the first and second distributions and the third distribution. And a recording pulse adjusting means for adjusting a recording pulse for the first classification;
An optical disc apparatus comprising: The classification means classifies by mark length,
The optical disc apparatus according to claim 1, wherein the pulse adjusting unit adjusts a mark length. The classification means classifies by space length,
The optical disc apparatus according to claim 1, wherein the pulse adjusting unit adjusts a space length. The classification means classifies the presence distribution related to the mark edge by mark length and space length,
The optical disc apparatus according to claim 1, wherein the pulse adjusting unit adjusts a mark edge position.   When the classifications of the plurality of marks or spaces are arranged in ascending order with respect to the clock cycle length, n is a natural number, and the overlapping of the distribution of the n + 1 and n + 2 classifications is increased, while the nth and n + 3 classifications The recording pulses for the (n + 1) th and (n + 2) th classifications are adjusted so as to reduce the overlap between the existence distribution of and the existence distributions of other classifications. The optical disk device described.   6. The recording pulse according to claim 1, wherein the recording period is adjusted within a range of ± (0.1T to 0.4T) with respect to the original recording pulse, where T is the clock period. An optical disk device according to the above.   The first distribution of the first classification is superimposed on the distribution of the second classification, while the distribution of the first and second classifications and the distribution of the third classification are not overlapped. 5. The optical disk apparatus according to claim 1, wherein recording pulses for one classification are adjusted.   When the classifications of the plurality of marks or spaces are arranged in ascending order with respect to the clock period length, the even-numbered class existence distribution is superimposed on the odd-numbered class existence distribution, or the odd-numbered class existence distribution is even-numbered. The optical disk apparatus according to claim 7, wherein the optical disk apparatus is overlaid on the existence distribution of the classification.   While the existence distribution of the first classification is superimposed on the existence distribution of the second classification that does not exist as the format of the optical disc, the existence distribution of the first classification, the existence distribution of the second classification, and the third distribution 5. The optical disc apparatus according to claim 1, wherein a recording pulse for the first classification is adjusted so that the classification distribution does not overlap.   10. The optical disc apparatus according to claim 9, wherein a clock cycle is T, and an existence distribution of the first classification is overlapped with an existence distribution of a classification of 1T or less.   When the classification of the plurality of marks or spaces is arranged in ascending order with respect to the clock cycle length, the existence distribution of the even-numbered classification is superimposed on the existence distribution of the classification of 1T or less, or the existence distribution of the odd-numbered classification excluding 1 The optical disk device according to claim 10, wherein the optical disc apparatus is superimposed on a distribution of existence of classifications of 1T or less. A jitter measurement method for an optical disc apparatus for recording information by irradiating a recording pulse light onto an optical disc to form marks and spaces,
Regenerating information recorded on the optical disc to generate a reproduction pulse signal;
Classifying a plurality of marks or spaces included in the reproduction pulse signal with a clock period as a reference unit;
Measuring presence distribution jitter or deviation for each classified mark or space;
To increase the overlap between the first distribution and the second distribution, while decreasing the overlap between the first and second distributions and the third distribution. Adjusting a recording pulse for the first classification;
A jitter measuring method for an optical disc apparatus, comprising:

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