JPH1125458A - Method and device for recording optical information - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for recording optical information, wherein stable signal decoding is performed even at a high transfer rate with small jitters. SOLUTION: This optical information recording device makes a modulation signal modulated to cause a recording signal to be the integral multiple of a basic cycle T in a master disk 2 and forms a pit in the master disk 2 by turning ON/OFF a laser beam based on the modulation signal. In this case, the modulation signal is set such that a shortest determination interval is three times or more than a specified basic cycle T, and the optical information recording device is provided with a modulation circuit 12 for determining the pattern of the modulation signal, a timing correction circuit 13 for adjusting the position of an edge according to the output of the modulation circuit 12 and a pulse correction circuit 14 for shortening a pulse width by a specified time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording apparatus and an optical information recording method, and can be applied to, for example, a compact disk (CD) recording apparatus. The present invention is to create a higher quality disc than before by recording pits using a higher laser power than before by controlling the timing of laser beam irradiation.

[0002]

2. Description of the Related Art Conventionally, for example, in a compact disk recording apparatus including such an optical information recording medium, data to be recorded is processed, and then EFM (Eight-to-F).
By performing ourteen modulation, a pit train having a period of 3T to 11T is formed with respect to a predetermined basic period T, whereby audio data and the like are recorded.

In response to this, a compact disk player irradiates a compact disk with a laser beam and receives return light, thereby obtaining a reproduction signal whose signal level changes in accordance with the amount of the return light. The signal is binarized at a predetermined slice level to generate a binarized signal. Further, the PLL circuit is driven from the binarized signal to generate a reproduction clock, and the binarized signal is sequentially latched by the reproduction clock, whereby the period 3T to 3T corresponding to the pit train formed on the compact disc is obtained.
Generate 11T playback data.

The compact disk player decodes the reproduction data generated in this way by data processing corresponding to data processing at the time of recording, and reproduces audio data and the like recorded on the compact disk.

Japanese Patent Application Laid-Open No. 58-212628 discloses such a conventional compact disk recording / reproducing, while changing the output power of a laser beam,
There is disclosed a disk recording apparatus in which pits are formed on a disk by reducing the pulse width of a pulse signal so as to obtain a reproduction signal that does not cause a deviation from a recording signal. Also, JP-A-3-83230 discloses that
A write pulse having a pulse width shorter by the pulse width corresponding to the pit extension caused by the thermal time constant of the optical recording medium is formed from the baseband signal, and the recording light pulse-width modulated by the write pulse is applied to the optical recording medium. There is disclosed an optical recording apparatus which forms a pit having a regular length on an optical recording medium having a large thermal time constant by irradiating the pit in accordance with a baseband signal. Japanese Patent Application Laid-Open No. Sho 62-54830 describes that recording is performed while sequentially changing the pulse width of the laser beam, and the pulse width of the laser beam when the pulse width of the reproduction signal reaches a predetermined length is selected. Therefore, even if the recording sensitivity differs for each disc or the laser beam intensity fluctuates with temperature, it is possible to set the optimum recording conditions based on the disc used and the environmental conditions, and to improve the reliability of the reproduced signal. An optical disk recording / reproducing apparatus that can be improved and that can realize high-density information recording is disclosed.

In recent years, it has become common to reproduce such a compact disc at a high transfer rate. In a reproducing apparatus having a high transfer rate, data is reproduced at a high speed by, for example, rotating a compact disk at a speed of eight times or more a predetermined number of revolutions. With such a high transfer rate playback device, the same amount of data can be obtained in a much shorter time than usual.

[0007]

In order to reproduce data at a high transfer rate, it is necessary to increase the number of rotations of the disk and to use a wide-band electronic circuit. Since broadband electronic circuits generally have a high noise level, in order to reproduce a stable signal even at a high noise level, it is necessary to reduce the jitter of the disk.

The present invention has been made in view of the above points, and has an optical information recording device and an optical information recording method capable of stably decoding a signal even at a high transfer rate with little jitter generated from a disk. It is intended to propose.

[0009]

According to the present invention, in order to solve the above-mentioned problems, a modulated signal whose signal level is switched at a period of an integral multiple of a predetermined basic period is generated based on data. Pits are formed on the optical recording medium, and at this time, recording is performed with the pulse width shortened so that the pulse width of the modulation signal for recording the 3T pit is 85% or less of the 3T pulse width.

For this reason, in an optical information recording apparatus, 3T
The output of the recording laser can be increased by the amount corresponding to the shortened pit pulse width. As a result, good pits are formed on the disk, and the level of noise reproduced from the disk can be reduced. Therefore, it is possible to reduce the jitter caused by the noise generated from the disk. Further, by finely adjusting the edge position of the recording pulse according to the recording pattern, it is possible to reduce the value of jitter due to intersymbol interference between signals recorded on the disk. As a result, even if the total jitter is reduced and the noise level is slightly increased at a high transfer rate, stable reproduction is possible.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an optical disk device according to an embodiment of the present invention. The optical disc apparatus 1 exposes a master disc 2 and outputs audio data SA output from a digital audio tape recorder 3.
Record In the manufacturing process of the optical disk, a mother disk is created by developing the disk master 2 and then electroforming to create a stamper from the mother disk. Further, in the optical disk manufacturing process, a disk-shaped substrate is formed from the stamper thus formed, and a reflective film and a protective film are formed on the disk-shaped substrate to form a compact disk.

That is, in the optical disk device 1,
The spindle motor 4 drives the disk master 2 to rotate,
The FG signal generation circuit held at the bottom outputs an FG signal whose signal level rises at every predetermined rotation angle. The spindle servo circuit 5 drives the spindle motor 4 in accordance with the exposure position of the disk master 2 so that the frequency of the FG signal becomes a predetermined frequency.
Is driven to rotate under the condition of constant linear velocity.

The recording laser 7 is constituted by a gas laser or the like, and emits a laser beam L for exposing the master disk. The light modulator 8 is configured by an electroacoustic optical element, and controls the laser beam L on / off in accordance with the modulation signal SD and outputs the laser beam L. The mirror 10 bends the optical path of the laser beam L and emits it toward the master disc 2.
The objective lens 11 condenses the light reflected by the mirror 10 on the master disc 2. These mirror 10 and objective lens 1
Reference numeral 1 denotes a disk master 2 by a thread mechanism (not shown).
The exposure position by the laser beam L is sequentially displaced toward the outer periphery of the disk master 2 in synchronization with the rotation of the disk master 2.

Thus, in the optical disc apparatus 1, a track is formed in a spiral by moving the mirror 10 and the objective lens 11 while the master disc 2 is driven to rotate, and pits are sequentially formed on the track in accordance with the modulation signal SD. To form

The modulation circuit 12 receives the audio data SA output from the digital audio tape recorder 3, and adds corresponding subcode data to the audio data SA. Further, the modulation circuit 12 performs data processing on the audio data SA and the subcode data according to the format of the compact disc, and
Generate B. That is, the modulation circuit 12 performs an interleaving process and an EFM modulation process after adding an error correction code to the audio data SA and the subcode data. As a result, the modulation circuit 12 generates a period (period 3T to 11T) that is an integral multiple of the basic period T for the pit formation.
An EFM modulated signal SB whose signal level changes at T) is output.

In the conventional optical disk recording apparatus, the EFM modulated signal SB produced as described above is sent to the optical modulator 8 as it is, and the light beam obtained from the laser 7 is turned on / off to form the optical disk master 2. Exposure was on top.

In the disk manufactured by such a conventional method, the slice level of the reproduced signal and the laser 7
Output powers corresponded in a one-to-one relationship. That is,
When a disk is manufactured with the output of the laser 7 increased, the slice level of the completed disk increases,
It has also been known that when a disk is manufactured with the output of the laser 7 reduced, the slice level of the completed disk decreases. By the way, in order to realize stable reproduction by all players, it is desirable that the slice level of the reproduction signal be at the center of the reproduction signal amplitude.

For example, in the standard of a disk such as a CD, the deviation of the slice level from the center of the amplitude of the reproduced signal is defined by the term "asymmetry". In a commercially available disk, the asymmetry value must be within a predetermined range. Is obliged. For this reason, it is necessary to control the output power of the laser 7 to a limited value, and it has been impossible to freely set the output power of the laser 7.

In the conventional method, it has been known that when the output of the laser 7 is increased, the pit width is increased. For this reason, the intersymbol interference of the completed disk also increases, and this increases the jitter, so that it is difficult to increase the output of the laser 7 to a certain value or more.

Therefore, in the present embodiment, the output signal SB of the modulation circuit 12 is sent to the timing correction circuit 13. In the timing correction circuit 13, the EFM
A change pattern of modulated signal SB is detected, and modulated signal SC is output according to the change pattern so as to reduce intersymbol interference from adjacent codes. By recording such a modulation signal SC, the problem that the reproduction signal level differs for each pattern in the reproduction signal of the manufactured disk is eliminated, and the jitter can be reduced.

In the present embodiment, the output signal SC of the timing correction circuit 13 is sent to the pulse width correction circuit 14, and is sent to the optical modulator 8 as a signal SD whose pulse width is shortened as a whole. By thus shortening the pulse width as a whole, it becomes possible to keep the asymmetry of the reproduction signal at a predetermined value even when recording is performed by increasing the output of the laser 7.

FIG. 2 is a block diagram showing the timing correction circuit 13. In the timing correction circuit 13, P
The LL circuit 16 generates and outputs a channel clock CK from the EFM modulated signal SB. Thus, in the modulation signal SB, the signal level changes at a period that is an integral multiple of the basic period T, so that the PLL circuit 16 changes the channel clock whose signal level changes according to the basic period T synchronized with the modulation signal SB. CK (see FIG. 5B) is generated and supplied to the rising edge correction circuit 17A and the falling edge correction circuit 17B.

The rising edge correction circuit 17A is provided with the configuration shown in FIG.
As shown in the figure, 13 latch circuits 19A to 19M operated by the clock CK are connected in series, and E is connected to this series circuit.
FM modulation signal SB is input. As a result, the rising edge correction circuit 17A samples the EFM modulation signal SB at the timing of the channel clock CK, and detects a change pattern of the EFM modulation signal SB from 13 consecutive sampling results. That is, for example, "00
01111000001 ", a length of 5T
It can be determined that the pattern is a change pattern in which pits having a length of 4T continue following the space. Similarly, "001111100000
When a latch output of "1" is obtained, it can be determined that the pattern is a change pattern in which a space of 5T in length is followed by a pit of 5T in length.

The correction value table 20 is formed of a read-only memory storing a plurality of correction data, and uses the latch outputs of the latch circuits 19A to 19M as addresses to generate correction value data DF corresponding to a change pattern of the modulation signal SB. Output. Monostable multivibrator (MM) 2
1 receives a latch output from the central latch circuit 19G among the 13 latch circuits connected in series, and for a predetermined period (a period sufficiently shorter than the period 3T) based on the rising timing of the latch output. ), And outputs a rising pulse signal whose signal level rises.

The delay circuit 22 has 15 stages of tap outputs, and the delay time difference between the taps is set to the resolution of the timing correction of the modulation signal in the edge position correction circuit 17A. The delay circuit 22 sequentially delays the rising pulse signal output from the monostable multivibrator 21 and outputs the delayed signal from each tap. The selector 23 selectively outputs the tap output of the delay circuit 22 in accordance with the correction value data DF, and thereby selectively outputs the rising pulse signal SS whose delay time changes according to the correction value data DF.

Thus, the rising edge correction circuit 17
A indicates that the signal level rises in response to the rising of the signal level of the EFM modulation signal SB, and the delay time Δr (3, 3) of each rising edge with respect to the EFM modulation signal SB.
3), Δr (4,3), Δr (3,4), Δr (5,
3),... Generate a rising edge signal SS that changes according to the change pattern of the EFM modulation signal SB.
(See FIG. 5D)

In FIG. 5A, a change pattern of the EFM modulated signal SB is represented by a pit length p in units of one cycle of the channel clock CK and a pit interval b shown in FIG. Is represented by Δr (p, b). Therefore, in FIG. 5D, the delay time Δr (4, 3) described second is a delay time when there is a blank of 3 clocks before a pit of 4 clocks in length. Thus, the correction value table DF stores the correction value data DF corresponding to all combinations of p and b.

As described above, the rising edge correction circuit 17A detects the pattern of the pits formed on the optical disk in the period 12T in units of the basic period T, and according to this pattern, the rising edge signal SS Will be generated.

The falling edge correction circuit 17B is different from the rising edge correction circuit 17A except that the monostable multivibrator 21 operates on the basis of the falling edge of the latch output and that the contents of the correction value table 20 are different. Is configured the same as

Thus, the falling edge correction circuit 17
B indicates that the signal level rises in response to the fall of the signal level of the EFM modulation signal SB, and the delay time Δf (3,
3), Δf (4, 4), Δf (3, 3), Δf (5,
4),... Generates a falling edge signal SR (FIG. 5C) that changes according to the change pattern of the EFM modulation signal SB. In FIG. 5C, the pit length p and the pit interval b are similar to the delay time with respect to the rising edge.
, The delay time for the falling edge is Δf
Indicated by (p, b).

Accordingly, the falling edge correction circuit 17B also generates a cycle 12T in units of the basic cycle T.
In the range, the pit pattern formed on the optical disk is detected, and the falling edge timing of the modulation signal SB, which is the timing of the end of the laser beam irradiation, is corrected according to this pattern, and the falling edge signal SR is Have been made to generate.

Flip-flop (F / F) 25 (FIG. 2)
Synthesizes and outputs the rising edge signal SS and the falling edge signal SR. That is, the flip-flop 25 inputs the rising edge signal SS and the falling edge signal SR to the set terminal S and the reset terminal R, respectively, whereby the signal level rises at the rise of the signal level of the rising edge signal SS and then falls. A modulation signal SC whose signal level falls at the rise of the signal level of the edge signal SR is generated. (FIG. 5D
SS, SR shown in FIG. 5C, and SC shown in FIG. 5E).

As a result, in the EFM modulated signal SB, the timing of the rising edge and the falling edge is output to the pulse width correction circuit 14 as a signal SC in which the timing is corrected according to the lengths of the preceding and following pits and lands.

The pulse width correction circuit 14 is realized by the configuration shown in FIG. In this figure, a timing correction circuit 1
The output signal SC from 3 is input to monostable multivibrators (MM) 30 and 31. The monostable multivibrator 30 generates a short pulse having a constant period in response to the rise of the signal SC. Similarly, the monostable multivibrator 31 is configured to generate a short pulse having a constant cycle in response to the fall of the signal SC. Monostable multivibrator 3
The output of 0 is input to the set terminal of the flip-flop 33 after being delayed by the delay element 32 by the fixed time T, and determines the rising timing of the output signal SD in the pulse width correction circuit 14. On the other hand, the output of the monostable multivibrator 31 is the flip-flop 3
3, the falling timing of the output SD signal of the pulse width correction circuit 14 is determined.

Thus, the output signal SD of the pulse width correction circuit 14 is formed as a signal whose only rising edge is delayed by the time T with respect to the output signal SC of the timing correction circuit 13. Therefore, the output signal S of the pulse width correction circuit 14
D has a pulse width always narrower by T than the output signal SC of the timing correction circuit 13.

With the output signal SD of the pulse width correction circuit 14 obtained as described above, the laser beam L is controlled on / off by the optical modulator 8 so as to irradiate the master disc 2.

As a result, in the optical disk apparatus 1, the positions of the leading edge and the trailing edge of each pit can be corrected in small steps so as to reduce the jitter caused by intersymbol interference during reproduction. Further, since the pulse width of the recording signal can be greatly reduced, the light amount of the laser beam L can be correspondingly increased.

FIG. 6 is a process chart for explaining the generation of the correction value table 20 used for the edge timing correction in this manner. In the optical disk device 1, by appropriately setting the correction value table 20, even when the light amount of the laser beam L or the recording pattern changes, the reproduction signal crosses a predetermined slice level at a correct timing synchronized with the clock CK. To

The correction value table 20 includes a rising edge correction circuit 17A and a falling edge correction circuit 17A.
B, but the generation method is the same except that the conditions for generation are different. Therefore, only the rising edge correction circuit 17A will be described here.

In this step, a master disc for evaluation is created by the optical disc apparatus 1, and a correction value table is set based on the reproduction result of the compact disc created from the master disc.

Here, when the master disc for evaluation is created, a correction value table 20 for evaluation reference is set in the optical disc apparatus 1. The correction value table 20 for the evaluation criterion is selected so that the selector 23 (FIG. 3) always selects and outputs the center tap output of the delay circuit 22.
The correction value data DF is set and formed. Thus, in this step, the timing correction circuit 13 is set to have no effect.

In the pulse width correction circuit 14, the delay element 32
Is set to, for example, 200 nsec. As a result, the time width of all recording pulses is changed to be shorter by 200 nsec. Accordingly, while the shortest pit (called 3T) is originally recorded with a pulse of about 694 nsec, the output from the pulse width correction circuit 14 is shortened to 494 nsec. When the effect of the pulse width change is calculated as a ratio for the shortest pit, it is found that the pulse width is about 70%, ie, 494/694 = 71%.

As described above, when the recording pulse length is 20
The signal SD shortened by 0 nsec is sent to the optical modulator 8, and the disk master 2 is exposed by a laser beam L having a power approximately twice as large as that used when producing a normal compact disk.

After the disk master 2 thus exposed is developed, electroforming is performed to form a mother disk, and a stamper 40 is formed from the mother disk. Further, a compact disc 41 is produced from the stamper 40 in the same manner as in a normal compact disc producing process.

The compact disc player (CD player) 42 reproduces the evaluation compact disc 41 created in this manner. At this time, the compact disk player 42 switches the operation under the control of the computer 44, and sends the reproduction signal RF whose signal level changes according to the amount of return light obtained from the compact disk 41 to the digital oscilloscope 43 from the built-in signal processing circuit. Output.

At this stage, jitter due to intersymbol interference is observed as in a normal compact disk. Also,
The asymmetry may be slightly off.

The digital oscilloscope 43 switches its operation under the control of the computer 44, performs an analog-to-digital conversion process on the reproduced signal RF at a sampling frequency 20 times the channel clock, and outputs a digital signal obtained as a result to the computer 44. .

The computer 44 controls the operation of the digital oscilloscope 43, processes the digital signal output from the digital oscilloscope 43, and sequentially calculates the correction value data DF. Further, the computer 44 drives the ROM writer 45 to sequentially store the calculated correction value data DF in the read-only memory, thereby forming the correction value table 20. An optical disc is finally manufactured based on the correction value table 20 thus completed.

FIG. 7 is a flowchart showing a processing procedure in the computer 44. In this processing procedure, the computer 44 proceeds from step SP1 to step SP2, and sets the jitter detection result Δr (p, b) and the number of times of jitter measurement n (p, b) to the value 0. Here, the computer 44 calculates the jitter detection result Δr (p, b) for each combination of the pit length p and the pit interval b before and after the edge to be subjected to the jitter detection, and calculates the jitter measurement number n (p, b). Count). Therefore, in step SP2, the computer 44 determines all the jitter detection results Δr (p, b) and the number of jitter measurements n (p,
b) is set to the initial value.

Subsequently, the computer 44 proceeds to step SP
3 and comparing the digital signal output from the digital oscilloscope 43 with a predetermined slice level, the digital signal obtained by binarizing the reproduction signal RF is output.
Generate a quantified signal. In this process, the computer 44 binarizes the digital signal so that a value equal to or higher than the slice level is 1 and a value lower than the slice level is 0.

Subsequently, the computer 44 proceeds to step SP
Then, the reproduction clock is generated from the binarized signal composed of the digital signal. Here, the computer 44
The operation of the PLL circuit is simulated by arithmetic processing on the basis of the digitized signal, thereby generating a reproduced clock.

Further, in the following step SP5, the computer 44 samples the binarized signal at the timing of each falling edge of the reproduced clock generated in this manner, and thereby decodes the modulated signal (hereinafter, the decoded signal). The modulated signal is called a decoded signal).

Subsequently, the computer 44 proceeds to step SP
6, and from the rising edge of the binarized signal,
The time difference e up to the falling edge of the reproduction clock closest to this edge is detected, and the jitter at this edge is measured in time. Then the computer 44
Is the pit length p before and after the decoded signal for the edge measured in step SP6 in step SP7.
And the pit interval b are detected.

The computer 44 subsequently proceeds to step SP
In step 8, the time difference e detected in step SP6 is added to the jitter detection result Δr (p, b) corresponding to the preceding and following pit length p and pit interval b, and the corresponding number of jitter measurements n (p, b) ) Is incremented by the value one. Subsequently, the computer 44 proceeds to step SP9, determines whether or not time measurement has been completed for all rising edges, and returns a negative result here to step SP5.

Thus, the computer 44 repeats the processing procedure of steps SP5-SP6-SP7-SP8-SP9-SP5, accumulatively adds the time-measured jitter detection results for each change pattern appearing in the reproduction signal RF, and adds the results. Count the number. Note that this change pattern corresponds to the latch circuit 19A in the rising edge correction circuit 17A.
In order to correspond to the number of stages of １９19M, the edge is classified by a period of six samples before and after the jitter detection target edge based on the basic period T (a period of 12T in total).

When the jitter time measurement is completed for all the edges in this way, the computer 44 obtains a positive result in step SP9,
The process proceeds to step SP10, where the time-measured jitter detection result is averaged for each change pattern appearing in the reproduction signal RF. That is, since the jitter detected in step SP6 is affected by noise, the computer 44 averages the jitter detection result in this way, and improves the measurement accuracy of the jitter.

After averaging the jitter detection result in this way, the computer 44 subsequently proceeds to step SP11.
The correction value data DF is generated for each change pattern based on the detection result, and the correction value data
Output to the OM writer 45. Here, this correction value data DF is calculated by executing the following equation with the delay time difference between taps in the delay circuit 22 being τ.

[0059]

Hr1 (p, b) = Hr0 (p, b) -a / τ
・ Δr (p, b)

Here, Hr1 (p, b) is a tap of the delay circuit 22 selected by the correction value data DF, and a value of 0 is a center tap. Hr0
(P, b) is a tap of the delay circuit selected by the correction value data DF that is an initial value. In this embodiment, Hr0 (p, b) is set to the value 0. . A is a constant. Here, in the present embodiment, a is set to a value of 1 or less (for example, 0.7 or the like), so that the correction value data is surely converged even if there is an influence of noise or the like.

When the computer 44 stores the correction value data DF generated in this manner in the ROM writer 45, the computer 44 proceeds to step SP12 and ends the processing procedure. Subsequently, the computer 44 executes the same processing procedure for the falling edge of the digital binary signal,
Thus, the correction value table 20 is completed.

The correction value table 2 completed in this way
The optical disk is manufactured in the optical disk device 1 by using 0. In the optical disk completed in this way, the recording power is increased about twice, so that the pit variation is reduced, and the disk has low noise. further,
Since the recording was performed with the recording pulse width shortened, the asymmetry conditions also satisfied the standard. Furthermore, the timing of laser beam irradiation is corrected according to the recording pattern,
Since the timings of the leading edge and the trailing edge of each pit are corrected, reproduction is performed with extremely small jitter.

In the above-described embodiment, a case has been described in which an optical disk is created by directly using the correction value table created from the optical disk for evaluation. However, the present invention is not limited to this, and the present invention is not limited to this. An optical disk for evaluation may be created again using the corrected correction value table, and the correction value table may be corrected using the newly created optical disk for evaluation. By thus correcting the correction value table repeatedly, jitter can be surely reduced.

Further, in the above-described embodiment, a case has been described in which the amount of jitter is measured by measuring the time of a binary signal with reference to a basic clock, and correction value data is generated from the measurement result. The present invention is not limited to this, and if sufficient accuracy for practical use can be ensured, correction value data is generated by detecting the signal level of the reproduced signal based on the basic clock instead of measuring the jitter amount by this time measurement. You may. In this case, an error voltage from the signal level of the detected reproduction signal to the slice level is calculated, and correction value data is calculated based on the error voltage and the transient response characteristic of the reproduction signal.

In the above-described embodiment, the case where the timing of the modulation signal is corrected in accordance with the correction value data tabulated has been described. However, the present invention is not limited to this. Instead of the previously detected correction value data, the correction value data may be calculated by an arithmetic processing, and the timing of the modulation signal may be corrected by this.

[0066]

According to the optical information recording apparatus of the present invention, a modulated signal is produced on an optical recording medium by modulating the recorded signal so as to be an integral multiple of a predetermined basic period, and a laser beam is emitted based on the modulated signal. An optical information recording device that forms a pit on the optical recording medium by turning on or off,
The modulated signal has a minimum judgment interval of 3 of the predetermined basic period.
A pattern detection means for determining the pattern of the modulation signal, a timing correction means for adjusting an edge position in accordance with an output of the pattern detection means, and a pulse width shortened for a predetermined time. Since the pulse width changing means is provided, it is possible to increase the output of the recording laser by an amount corresponding to the reduced pulse width. As a result, good pits are formed on the optical recording medium, and noise reproduced from the optical recording medium is reduced. And therefore, it is possible to reduce the jitter caused by noise generated from the optical recording medium. Further, by finely adjusting the edge position of the recording pulse according to the recording pattern, there is an effect that the value of jitter due to intersymbol interference between signals recorded on the optical recording medium can be reduced. As a result, even if the total jitter is reduced and the noise level is slightly increased at a high transfer rate, an effect of enabling stable reproduction can be obtained. Therefore, by controlling the timing of laser beam irradiation and recording after increasing the amount of laser beam,
There is an effect that it is possible to manufacture an optical recording medium having excellent characteristics which cannot be considered so far.

Further, in the optical information recording apparatus of the present invention, in the above, the pulse width changing means changes the output pulse width when the pulse width of the modulation signal corresponds to three times the basic period. Approx. 85% for 3 times the above basic cycle
Since the adjustment is made as follows, the signal whose recording pulse length is shortened is optically modulated, and a laser beam having approximately twice the power used in normal optical information recording is placed on the optical recording medium. Irradiation can be performed, whereby the pulse width can be shortened as a whole, and the asymmetry of the reproduction signal can be maintained at a predetermined value.

In the optical information recording apparatus according to the present invention, the timing correction means may generate a binarized signal by binarizing a reproduction signal obtained from the optical recording medium at a predetermined slice level. Since the timing of the modulation signal is corrected so that the binary signal changes with reference to the basic period, the jitter detection result measured in time for each change pattern appearing in the reproduced signal. Is obtained, and the effect of improving the jitter measurement accuracy can be obtained.

In the optical information recording apparatus according to the present invention, the timing correction means has correction data storage means, and corrects the timing of the modulation signal in accordance with the correction data stored in the correction data storage means. However, since the correction data is set based on the reproduction result of the optical recording medium for evaluation, the optical recording medium can be manufactured using the correction data storage means, and the recording power is increased. In addition, the pit variation is reduced, and a low-noise optical recording medium can be obtained. Further, since the recording is performed with the recording pulse width shortened, the asymmetry condition can also satisfy the standard. Further, since the timing of laser beam irradiation is corrected in accordance with the recording pattern and the timing of the leading edge and trailing edge of each pit is corrected, it is possible to obtain a reproduction signal with extremely small jitter. .

Further, according to the optical information recording method of the present invention, the signal level of the modulation signal is switched at a period that is an integral multiple of a predetermined basic period, and the laser beam is modulated according to the modulation signal to form pits sequentially. In the optical information recording method for recording desired data, recording is performed such that a reproduction signal obtained from the pit has at least three times the basic period, and the length of the reproduction signal is equal to the basic period. When recording a pit that is three times longer,
Since the pulse time width of the recording signal corresponding to the reproduction signal is about 85% or less of the pit having a length three times as long as the basic period, a signal having a shorter recording pulse length. Is optically modulated, and a laser beam having approximately twice as much power as that used in normal optical information recording can be irradiated onto the optical recording medium, thereby shortening the overall pulse width. As a result, the asymmetry of the reproduced signal can be maintained at a predetermined value. In addition, since the recording power is increased, variations in pits are reduced, and a low-noise optical recording medium can be obtained. In addition, the timing of laser beam irradiation is corrected according to the recording pattern, and By correcting the timings of the leading edge and the trailing edge, it is possible to obtain a reproduction signal with extremely small jitter.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an optical disk device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a timing correction circuit of the optical disk device of FIG.

FIG. 3 is a block diagram illustrating a rising edge correction circuit in the timing correction circuit of FIG. 2;

FIG. 4 is a block diagram showing a pulse width correction circuit of the optical disk device of FIG. 1;

FIG. 5 is a timing chart for explaining the timing of the timing correction circuit of FIG. 2;
B, FIG. 5B shows the channel clock CK, FIG. 5C shows the falling edge signal SR, and FIG. 5D shows the rising edge signal S.
S, FIG. 5E shows the modulated signal SC.

FIG. 6 is a process chart showing a process of creating a correction value table in the optical disk device of FIG. 1;

FIG. 7 is a flowchart showing a processing procedure of a computer in the process of FIG. 10;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk apparatus, 2 ... Disk master, 8 ... Optical modulator, 12 ... Modulation circuit, 13 ... Timing correction circuit, 14 ... Pulse width correction circuit, 17A, 17B ... Edge position correction circuit, 20 ... Correction value table, 41 ...
Compact disc, 42 ... Compact disc player, 44 ... Computer

Claims (9)

[Claims] 1. An optical recording medium comprising: a modulation signal produced by modulating a recording signal so as to be an integral multiple of a predetermined basic period on an optical recording medium; and turning on or off a laser beam based on the modulation signal. In an optical information recording apparatus for forming pits on a medium, the modulation signal may have a shortest determination interval of 3 times the predetermined basic period.
A pattern detecting means for determining a pattern of the modulation signal, a timing correcting means for adjusting an edge position according to an output of the pattern detecting means, and a pulse width shortened for a predetermined time. An optical information recording device comprising pulse width changing means. 2. The pulse width changing means, when the pulse width of the modulation signal is equivalent to three times the basic period, makes the output pulse width approximately 85% of three times the basic period. The optical information recording apparatus according to claim 1, wherein the adjustment is performed as follows. 3. The timing correction means according to claim 1, wherein the reproduction signal obtained from the optical recording medium is divided into two at a predetermined slice level.
The timing of the modulation signal is corrected so that the binarized signal changes with reference to the basic period when the binarized signal is generated by binarization. Item 2. The optical information recording device according to item 1. 4. The apparatus according to claim 1, wherein the timing correction means converts a reproduction signal obtained from the optical recording medium into a signal having a predetermined slice level.
The timing of the modulation signal is corrected so that the binarized signal changes with reference to the basic period when the binarized signal is generated by binarization. Item 3. An optical information recording device according to item 2. 5. The timing correction means has a correction data storage means, and corrects the timing of the modulation signal according to the correction data stored in the correction data storage means, wherein the correction data is an optical recording for evaluation. 2. The optical information recording apparatus according to claim 1, wherein the setting is performed based on a reproduction result of a medium. 6. The timing correction means has correction data storage means, and corrects the timing of the modulation signal in accordance with the correction data stored in the correction data storage means, wherein the correction data is an optical recording for evaluation. 3. The optical information recording apparatus according to claim 2, wherein the setting is performed based on a reproduction result of the medium. 7. The timing correction means has correction data storage means, and corrects the timing of the modulation signal in accordance with the correction data stored in the correction data storage means, wherein the correction data is an optical recording for evaluation. 4. The optical information recording apparatus according to claim 3, wherein the setting is performed based on a reproduction result of the medium. 8. The timing correction means has correction data storage means, and corrects the timing of the modulation signal in accordance with the correction data stored in the correction data storage means, wherein the correction data is an optical recording for evaluation. The optical information recording apparatus according to claim 4, wherein the setting is performed based on a reproduction result of the medium. 9. Optical information for switching a signal level of a modulation signal in a cycle of an integral multiple of a predetermined basic cycle, modulating a laser beam in accordance with the modulation signal, sequentially forming pits, and recording desired data by the pits. In the recording method, recording is performed such that a reproduction signal obtained from the pit has at least three times the length of the basic period. When recording, the pulse time width of a recording signal corresponding to the reproduction signal is about 85% or less of a pit having a length three times the basic period. Method.